Radiological evaluation of OrthAlign -a novel handheld ...repository-tnmgrmu.ac.in/9511/1/220201118abhishek_jirel.pdf · Dr. Vrisha Madhuri, Dr. Thomas Palocaren, Dr. Abhay, Dr. Alfred

Radiological evaluation of OrthAlign -a novel handheld

navigation system used in total knee replacement

Radiological evaluation of OrthAlign -a novel handheld

navigation system used in total knee replacement

Dissertation submitted to the Tamil Nadu Dr. M.G. Medical University in partial

fulfilment of the requirement for the M.S Degree Examination Branch II (Orthopaedic Surgery) May 2018

CERTIFICATE

This is to certify that the dissertation titled “Radiological evaluation of OrthAlign -a

novel handheld navigation system used in total knee replacement” is a bonafide work

of Dr. ABHISHEK JIREL, in the Department of Orthopaedic Surgery, Christian

Medical College and Hospital, Vellore.

This is in partial fulfilment of the rules and regulations Of the Tamil Nadu Dr. M.G.R

Medical University for the award of M.S Degree Branch II (Orthopaedic Surgery),

under the supervision and guidance of Prof. Dr. PRADEEP POONNOOSE during

the period of his post-graduate study from April 2016 to May 2018.

This consolidated report presented herein is based on bonafide cases, studied by the

candidate himself.

Signature: Head of Department Professor Dr. V.T.K. Titus D.Orth, M.S.Orth, Dip.N.B Orthopaedics Christian Medical College Vellore- 632004

CERTIFICATE

This is to certify that the dissertation titled “Radiological evaluation of OrthAlign -a

novel handheld navigation system used in total knee replacement” is a bonafide work

of Dr. ABHISHEK JIREL, in the Department of Orthopaedic Surgery, Christian

Medical College and Hospital, Vellore.

This is in partial fulfilment of the rules and regulations Of the Tamil Nadu Dr. M.G.R

Medical University for the award of M.S Degree Branch II (Orthopaedic Surgery),

under the supervision and guidance of Prof. Dr. PRADEEP POONNOOSE during

the period of his post-graduate study from April 2016 to May 2018.

This consolidated report presented herein is based on bonafide cases, studied by the

candidate himself.

PRINCIPAL Dr. Anna Pulimood,

Principal, Christian Medical College, Vellore

DECLARATION CERTIFICATE

This is to declare that the dissertation titled “Radiological evaluation of OrthAlign -a

novel handheld navigation system used in total knee replacement” in the department

of Orthopaedics is my own work, done under the guidance of Dr. Pradeep Poonnoose,

Professor and head of Orthopaedics Unit II, submitted in the partial fulfilment of the

rules and regulation for the M.S Orthopaedics degree examination of the Tamilnadu

Dr. M.G.R Medical University, Chennai to be held in May 2018.

Dr.ABHISHEK JIREL

MS Post Graduate Registrar Department of Orthopaedics

Christian Medical College, Vellore

ACKNOWLEDGEMENTS

First and foremost, I would like to express my sincere gratitude to Professor Dr.

Pradeep Poonnoose for allowing me to choose the topic of my dissertation which was both interesting and of significant clinical value to Orthopaedic surgeons of all

generations. I would like to thank him for his patience, kindness and the unlimited time he has invested in the compilation of my dissertation and in me throughout the duration of my course.

I would like to further thank my co-guides Dr. Anil Oommen (Professor, Department

of Orthopaedics – Unit 2, CMC Vellore), and Dr Vignesh Prasad for their guidance and support.

I would also like to thank Mr. Bijesh Yadav (Department of Biostatistics, CMC Vellore) for all his efforts towards the statistical analysis which would not have been possible without his help.

I also would like to thank all the patients and their families who volunteered to be a part of my research and dissertation, without whom none of this would be possible.

I am eternally grateful to all my teachers for their invaluable insights, guidance and support throughout the duration of my course. I would like to thank Dr. Vernon N.

Lee, Dr. Vinoo M. Cherian, Dr. Manasseh N., Dr. Kenny S. David, Dr. Venkatesh K., Dr. Rohit Amritanand, Dr. V.T.K. Titus , Dr. Anil T. Oommen,

Dr. Vrisha Madhuri, Dr. Thomas Palocaren, Dr. Abhay, Dr. Alfred Job Daniel, Dr. Thilak Jepegnanam, Dr. P.R.J.V.C Boopalan.

I would also like to thank the rest of the teaching faculty who have been invaluable sources of knowledge and inspiration for me, Dr. Alfred Cyril Roy, Dr. Dan Barnabas, Dr. Sandeep Albert, Dr. Jeremy Bliss, Dr. Azeem Jabbar, Dr. VJ Chandy, Dr. Jerry

George, Dr. Hariharan, Dr. Sumant Samuel, Dr. Abel Livingston, Dr. Kaushik Bhowmick, Dr. Jerry Nesaraj, Dr. Chandrasekhar.

I wish to thank my colleagues for their constant help and support during my entire study and Post graduate program. I would like to personally thank Dr. Elvis Benjamin,

Dr. Anil Chintada, Dr. Vinay T. Kuruvilla, Dr. Apurve, Dr. George Srampical, Dr. Banteilang, Dr.Raunak Milton, Dr. Ajit Matthew, Dr. Chandan, Dr. Benjamin Matthew, Dr. Febin,Dr. Nirvin Paul, Dr. Anto Anand, Dr. Joseph George, Dr. Rahul George, Dr. John Premnath, Dr. Reuben Cedric, Dr. Pandian, , Dr. Ramu, Dr. Jacob,

Dr. Siddharth, Dr. Arun John Paul, Dr. Arunkumar, Dr. Roncy, Dr. Arun Gandhi, Dr. Jonath Samuel, Dr. Ashwin Sitaram and Dr. Samuel Santosh.

I would like to thank GOD for his limitless blessings and opportunities that I have

been fortunate to receive.

Not least of all I would like to express my unbound love and appreciation to my family, Dr Olak Bahadur Jirel, Mrs Jasmine Jirel and Dr Archana Jirel who have been

pillars of support and encouragement throughout my life and to whom I owe everything.

TABLE OF CONTENTS

1. INTRODUCTION……………………………………………………1 2. AIM AND OBJECTIVES……………………………………………4

3. LITERATURE REVIEW ……………………………………………6 4. MATERIALS AND METHODS……………………………………38

5. RESULTS …………………………………………………………...55 6. DISCUSSION ……………………………………………………….74

7. LIMITATIONS ……………………………………………………...80 8. CONCLUSION ……………………………………………………...82 9. BIBLIOGRAPHY …………………………………………………. 85 10.ANNEXURES ……………………………………………………...88

Introduction

1

Introduction:

Osteoarthritis is defined as a degenerative condition of synovial joints which leads to

progressive degeneration of articular cartilage. This condition is seen in the weight

bearing joints with the knee joint which is most commonly affected. Up to 80 percent

of all osteoarthritis occurs in the knee joint (1)

Osteoarthritis of the knee is an increasingly common cause of knee pain and impaired

mobility in the elderly population (2). Data regarding incidence of osteoarthritis of the

knee in our local population is lacking, however in the USA, in a population group of

patients >65 years of age, up to 80% of patients were found to be affected (3).Any

alteration in the hip and knee joint, can influence the development of OA. It has been

postulated that lower-extremity alignment can have an effect on the onset of OA.

Patients who have a varus alignment (genu varum) are at increased risk of medial

tibial-femoral OA, while those with a valgus alignment (genu varum) are at risk for

lateral tibial-femoral OA (9)

2

Total knee arthroplasty as a modality of treatment for end stage degenerative

knee osteoarthritis provides pain relief to the patient and also improves function

significantly. Distal femoral and proximal tibial bone cuts are traditionally made using

extra/intramedullary alignment systems. However significant degrees of errors in

mechanical axis alignment (greater than 3 degrees) has been reported ranging from 22

to 35 percent of routine total knee arthroplasties (5). Immediate post-operative

component malposition has an influence on overall limb alignment, lifespan of the

components and overall function. It has been shown to compromise the long-term

survival of TKA. Specifically, malalignment of greater than 3° can lead to off-axis

loading, polyethylene wear, implant loosening, and increases the rate of revision by up

to 24 %(6)

Computer assisted navigation systems (CAS) were developed as an alternative method

to ameliorate problems of malposition of components and overall mechanical axis

misalignment. These CAS systems have shown to decrease component malalignment

to between 3 and 19 percent(6). However this technology was not widely adopted in

view of the increased costs, prolonged intraoperative period and need for cumbersome

and often large apparatus.

Accelerometer based navigation systems for TKR do not require the large consoles

needed for CAS. The purpose of this study is to determine the accuracy of one such

system in tibial and femoral component placement and its subsequent effect on the

surgical procedure.

3

Aims and Objectives

4

Aims:

To determine the accuracy of cuts made with OrthAlign -a novel handheld navigation

system used in total knee replacement.

Objectives:

To compare the accuracy of two methods used to make the distal femoral and

proximal tibial cuts in total knee arthroplasty. The OrthAlign – a hand held

accelerometer based system will be compared with the traditional extra medullary jigs.

1. To determine the accuracy of the two systems in making distal femur and

proximal tibia cuts.

2. To determine the overall alignment of the limbs following surgery using the

two methods

5

Literature Review

6

Literature Review

Biomechanics of the Knee joint:

The main aim in total knee arthroplasty is to achieve excellent alignment of the

lower limb and accurate placement of components. There are various axes

described for the knee joint which can be applied to ensure maintenance of the

limb alignment during the surgery.

Vertical Axis

The vertical line which extends distally from the pubic syphilis on a standing

stitch radiograph. This axis is used as a reference axis/line from which the

other axes are determined.

Mechanical Axis:

The mechanical axis of the lower limb is determined by drawing a line from the

centre of the femoral head to the centre of the ankle joint. This line forms

approximately 3° slope compared with that of the vertical axis (10).

This can be subdivided into the femoral and tibial mechanical axis.

7

The femoral mechanical axis starts on the centre of the head of femur and ends at the

intercondylar notch of the distal femur. The tibial mechanical axis starts from the

centre of the proximal tibia and ends in the centre of the ankle.

The medial angle formed by the femoral and tibial mechanical angle is called the hip-

knee-ankle angle. This angle is representative of the overall limb alignment and is

usually <180 degrees in value.

Anatomical Axis

The anatomical axis in the lower limb bones is in relation to the intramedullary canal

axis. There is an approximate 5°–7° of inclination difference compared to the

mechanical axis for the femur. For the tibia – both are the same. Furthermore the

anatomical axis can be altered by any femoral or tibial deformities, as well as the

patient’s hip angle.

8

Figure 1 Diagram showing the anatomical versus mechanical axis of the lower limb

9

Kinematic Axis

Kinematic axis of the knee is described in terms of 3 functional axes about which the

knee rotates during dynamic motions of the knee.

Transverse axis of the femur

The tibia flexes and extends along this axis, and it passes through the center of

a circle that fits the femoral condyles (11).

Transverse axis of the patella

This is the axis around which the patella flexes and extends in relation to the

(10). It is located anterior, proximal, and in parallel to the first transverse axis.

Longitudinal axis

This is perpendicular to the previous 2 axes and movements of internal and

external rotation of the tibia in relation to the femur occurs along this axis.

There are many systems of knee replacement that make their cuts based on this

axis rather than the mechanical axis. There are a lot of studies that compare the

two, and so far there is no conclusive evidence that one is superior to the other.

Kinematic axes of the knee

10

Rationale:

Limb alignment and soft tissue balancing are paramount in knee arthroplasty.

Malalignment may have a negative impact on the implant survival and long term

result of Total knee (11). Malalignment may lead to off-axis loading, increased

polyethylene wear, and subsequent implant loosening therefore decreasing the

survival of the implant (15)

Therefore accurate placements of implants, maintenance of alignment and soft tissue

balancing is of paramount importance in total knee arthroplasty.

Despite the use of manual intramedullary or extra medullary guides, significant errors

in postoperative mechanical axis of greater than 3° are estimated to occur in at least

10% of TKAs, including those performed by experienced surgeons (16). Other studies

paint a poorer picture where they reported up to 22 to 35 percent of routine total knee

arthroplasties were malaligned(14) (>3 degrees) .

11

Total knee Arthroplasty and alignment issues:

Total knee arthroplasty (TKA) is an effective solution to improve limb function and

subsequently, quality of life in patient with end stage osteoarthritis of the knee.

The indications for undergoing TKA include

Debilitating pain affecting activities of daily living.

Failure of conservative management of knee osteoarthritis pain.

Surgically fit individual.

No active infections in the body.

The technical goals of TKA include

Restore neutral mechanical alignment of limb.

Restore joint line

Balanced ligaments

Normal Q angle

12

Techniques of distal femur and proximal tibia resection in total knee

arthroplasty:

There are a total of 7 bone cuts in a typical (7).

1. Distal femur

2. Anterior femur

3. Posterior femur

4. Anterior chamfer

5. Posterior chamfer

6. Tibia

7. Patella

13

Methods of bony resection in TKA:

Conventional Extra medullary/ intramedullary guides:

The commonly used method of measuring and resecting the distal femur and proximal

tibia in total knee arthroplasty is done using external jigs which can be extra or intra

medullary. In this method, the cutting block position is set at a fixed resection angle

relative to the intramedullary alignment rod, where the same degree of valgus is

assumed as correct for all distal femurs (e.g., 3-7°) depending on the preoperative

valgus alignment. This is done as an attempt to create a distal femoral resection

perpendicular to the femoral mechanical (15)).

The disadvantage of using extra medullary and intramedullary jigs is that the distal

femur valgus angle is assumed and not measured in individual patients which may

lead to malposition of the cutting block and errors in implant placement.

14

Distal femur canal entry being made 1 cm

above the insertion of the posterior cruciate ligament and slightly medial in the

intercondylar notch.

Distal femur cut is made using the intramedullary adjustable distal Resection guide

after adjusting for the valgus angle.

15

Extra medullary tibial guide for measurement of proximal tibia resection.

The slope of the tibial implant can be adjusted by moving the external jig forward. In

a CR knee, the slope usually corresponds to the native slope of the tibia, whereas for

PS knee, due to the increase in flexion space caused by the release of the PCL, a 3

degree or 0 degree slope is preferred. In this study- CR knees were used.

16

Computer aided Navigation systems (CAS):

Navigation systems take the positions of patients' anatomical reference points and

surgical instruments are transferred to a computer and processed using software that is

capable of providing surgeons with information in a visual or graphical form. This

data is used to guide the distal femur and proximal tibia cuts in TKA.

CAS system being used to guided distal femur cuts in TKA. Rigid sensors with infrared transmitters are attached to the distal femur, tibia and the cutting guide.

17

The system itself may be of different types. The images of the knee bony landmarks

may be acquired preoperatively or intraoperatively, or may be independent of images.

In image-based systems, the software works with images acquired previously using

CT or MRI, or intraoperatively using fluoroscopy along with data from the sensors to

guide distal femur and proximal tibia cuts.

In image-free navigation, the computer computes anatomical reference points acquired

during the surgical procedure, in which some regions and reference points are

digitized. The method most used for transmitting information to the system uses

infrared signals

Figure of Basic representation of a CAS module with (a) Optical tracking camera. (b)

Computer (c) Monitor

18

Monitor showing the recommended level of resection in distal femur.

19

Advantages of CAS:

CAS is a precision instrument for carrying out the operation, and is particularly useful

in terms of distorted bony anatomy due to deformities or any previous trauma where

use of intramedullary guide rod is not (16).

There have been studies where authors have shown significantly decreased blood loss

with navigation systems as intramedullary femoral guide is not used. Millar et all

found in their study that the mean true blood volume loss across was significantly

(p<0.001) less in the computer assisted group (1014±312ml) compared to the

conventional group (1287±330ml (17). They however reported no difference in

transfusion rates between the CAS and Control group.

It has also been shown to be a good teaching tool, given that the effect of each action

performed during the operation can be seen immediately.

It also has the effect of helping with intraoperative decisions, by providing an option

of simulating actions before implementing them.

20

Disadvantages of CAS:

Cost operation of CAS is a serious consideration especially in developing countries.

Novak et all reported that Computer-assisted surgery is both more effective and more

expensive than mechanical alignment systems. Given an additional cost of $1500 per

operation (18).

The instrumentation for CAS can be cumbersome as there are many different parts

which need to be assembled or applied intraoperatively. There is also a steep learning

curve which together can prolong the intraoperative time.

21

Accelerometer based handheld navigation system in TKA (OrthAlign)

Orthalign is a palm size hand held navigation system for use in TKA. It makes

the use of accelerometers and gyroscopes, both a type of inertial sensors with varied

applications from smart phones to various military applications in missiles and drones.

22

Surgical Technique:

Femur Navigation:

1. The first step following exposure of the knee joint is to secure the

microblock and sensor on distal femur.

2. The centre pin is placed at the same site as IM guide rod placement in

analogue guides following which the AP offset is entered.

23

3. The next step is to calculate the femur centre of rotation and this is

carried out by manoeuvring the leg in medial to lateral direction and

flexion and extension of the hip.

24

4. The resection plane and is calculated by the navigation unit and the desired resection depth is set by the surgeon. The remaining steps of

distal femur resection is same as in a traditional TKR.

25

Tibia Navigation:

5. Align proximal guide with medial 1/3 of tibial tubercle and place the

stylus over the ACL footprint.

26

6. The medial and lateral malleolus locations as well as offset are

registered

27

7. The resection plane is calculated and the resection depth is entered by

the surgeon.

28

Advantages of OrthAlign system:

Patient Specific: The system carries out calculations and recommends bony

cuts based on the individual patients anatomy.

Real-time alignment data: Data regarding the specifics of bony cuts are shown

on the screen in real time and any changes made in the measuring guide in

relation to the bony anatomy of the patient is available in numerical and

graphical form. This can help the surgeon visualize the cuts before actually

making them.

Fully intra-operative and works within surgeon’s workflow

Accuracy of navigation without big computers and expensive equipment

Simple, easy to use

No lead time, pre-op prep, or additional planning required

No line of sight issues

No need for intramedullary rods: This can be particularly advantageous in

instances where use of IM rods are not feasible. E.g. In patients who have

femur deformities or in patients who have undergone prior surgical intervention

with implant or implants insitu.

Works with any implant: The use of OrthAlign technology is not limited to a

single system and implants from any manufacturer may be used following bony

resection with the use of OrthAlign.

29

Disadvantages of OrthAlign hand held navigation system:

Cost: In the Indian setting, the system adds an additional cost of Rs 30000/-

per case. Despite the fact that one unit can be used for bilateral TKR in the

same patient, in view of significantly cheaper operation costs in our region as

compared to the United States, increase in percentage of total cost of surgery is

significant. Currently there are no studies which analyses the cost affectivity of

this navigation system in the Indian setting.

Single Use: A single unit of this system can be used only once which has a

greater impact on the cost of surgery.

30

Literature on Handheld navigation for total knee arthroplasty (Orthoalign) vs.

conventional analogue guides.

Denis Nam Et all (19) demonstrated in a randomised control trial that compared to

conventional extra medullary guides, Orthalign significantly reduces the number of

“outliers” for tibial component alignment in both the coronal and sagittal planes.

However, they found no statistically significant difference in mechanical alignment

between the two groups, with 89.4% in the OrthAlign cohort, and 74.5% in the

conventional cohort, being within 3° of a neutral mechanical axis.

Denis Nam Et all (24) demonstrated that the OrthAlign 2 system is accurate for

performing the distal femoral resection in TKA. The study reported that 95.8% of the

femoral components were aligned within 2° of perpendicular to the femoral

mechanical axis and 93.8% of patients had an overall mechanical alignment within 3°

of a neutral mechanical axis.

Eddie H. Huang et all (26) carried out a prospective, single-arm study of patients

undergoing an elective primary TKA using the Orthalign (knee align 2) system for

navigation and creating distal femur and proximal tibia cuts. The mean femoral

coronal alignment was 0.8° ±2.2° varus with 13% of the femoral components were

placed in greater than 3° of coronal malalignment.

31

The mean tibial coronal alignment was 0.09° ± 1.4° varus with 3.8% of tibial

components were placed in greater than 3° of coronal malalignment.

The mean tibial slope was 3.3° ±1.8° and 5.7% of tibial components were placed in

greater than ± 3° of targeted tibial posterior slope.

The mean mechanical axis was 0.2° ± 2.1° valgus (range, 5.3° varus–5.3°

valgus); 17% of knees had greater than 3° of coronal malalignment.

William Bugbee et (20) conducted a prospective single arm study of 90 patients who

underwent TKA using OrthAlign navigation. They reported 93.3% accuracy in

coronal alignment for tibial component in coronal plane with only 6.7% of patients

found to have alignment outside of ±3°. With respect to sagittal alignment, the

OrthAlign system was 95.5% accurate in creating posterior slope within ±3° of the

intraoperative goal.

Reed et all (21) carried out a randomized prospective study of 135 patients who

underwent TKA using traditional extra medullary guides and found an accuracy of 65

percent of tibial components were aligned within the required parameters. The rest of

the study population were outliers.

Denis Nam et (22) carried out a series of cadaveric analysis of bony cuts in TKA

using OrthAlign navigation system. Four orthopaedic surgeons carried out bony

resection in 5 separate cadavers each. With regard to the varus/valgus alignment of

32

the tibial resections, 95% was found to be within 2° of the preoperative “target” using

both plain radiograph and CT scan .measurement.

The mean absolute difference between the preoperative “target” and tibial resection

alignment angle was 0.77° ± 0.64° using plain radiograph measurements, and 0.68° ±

0.46° using CT scan measurements. They also reported that, 95% of the tibial

resections were found to have a posterior slope within 2° of the preoperative “target”

for both plain radiograph and CT scan measurements.

Iorio R et (23) conducted a single arm prospective study where 53 patients underwent

TKA using OrthAlign Navigation. They reported 96 % of the tibial components were

positioned 90°±2 to the mechanical axis, and 100 % of the components were placed

90±3° to the mechanical axis.

33

Comparison of CAS vs. Analogue guides:

Computer assisted navigation systems (CAS) were developed as an alternative method

to ameliorate problems of malposition of components and overall mechanical axis

misalignment. And have been shown to decrease component malalignment to between

3 and 30 percent (16).

A meta-analysis conducted by Mokshal et all reported that mechanical axis deviation

from neutral was significantly lower for CAS (P<0.0293) and tibial component

alignment deviation from neutral was significantly lower for the CAS group

(p<0.0263).

The rates of outliers were significantly lower for the CAS group (p<0.0001): including

anatomic axis outliers, coronal plane outliers for tibial and femoral components, and

slope outliers for tibial and femoral components.

Anderson et all(18) reported that in their study, the control group postoperative

mechanical axis was within 3° of neutral alignment in 84% of cases compared with

95% for the navigation group (P < .02). The postoperative tibial component alignment

was in 0.5° of varus in the conventional group and neutral (0.0° of valgus-valgus) in

the navigation group (P < .05).

84 percent of the control group was within 2° of varus or valgus compared with 97%

in the navigation group (P < .005).

34

Tibial posterior slope was 3.9° in the control group and 3.0° in the navigation group

(P < .03). The control group's tibial slope was between 2° and 5° in 55% of the cases

vs. 67% for the navigation group (P < .02)

The postoperative femoral component coronal alignment was 0.8° of valgus in the

conventional group and 0.5° of varus in the navigation group (P < .001). The

conventional group had 80% of patients within 2° of varus or valgus compared with

85% in the navigation group (P < .02)

35

Comparison of CAS vs. Handheld accelerometer based navigation system

(Orthoalign)

Denis Nam et all (24) conducted a study titled,” Accelerometer-based, portable

navigation vs. imageless, large-console computer-assisted navigation in total knee

arthroplasty: a comparison of radiographic results.” (Journal of Arthroplasty, 2013

Feb)

This was a Retrospective cohort study where the comparison of radiographic

parameters was done between Orthalign and Large-Console Computer-Assisted

Navigation system (AchieveCAS).

The authors reported that the percentage of patients who had an alignment within 3°

of a neutral mechanical axis in the OrthAlign cohort was 92.5% vs. 86.3% in the

AchieveCAS cohort.

Significant differences were observed in the accuracy of femoral

component alignment, with 94.9% of patients in the OrthAlign 2 cohort having an

alignment within 2° of neutral vs. 92.5% in the AchieveCAS cohort.

Both methods were equally accurate with regard to tibial component positioning. The

OrthAlign device also demonstrated a significant decrease in tourniquet times. The

mean tourniquet time in OrthAlign cohort was 48.1 ± 10.2 minutes vs. 54.1 ± 10.5

minutes in the Achieve CAS cohort.

36

Mason JB (12) et all, conducted a meta-analysis comparing literature from 1990 to

2007 which compared results of traditional analogue extra medullary guides to various

CAS systems. They analysed a total of 29 studies and found that mechanical axis

malalignment of 9.0% of CAS vs. 31.8% of conventional TKA patients.

37

Materials and Methods

38

Materials and Methods:

All patients who presented with end stage osteoarthritis of the knees between July

2016 and July 2017 to the Orthopaedic Unit 2, were prospectively enrolled for the

study. The study arm consisted of patients for whom the OrthAlign hand held

navigations system was used for proximal tibial and distal femoral resection. Controls

included patients who had TKA using the traditional extra medullary alignment jigs

during the same period. The alignment of the patient’s knee joints were analysed by

comparing preoperative and postoperative full length standing stitch view radiograph

of bilateral lower limbs.

Patient selection:

o All patients who requested a knee replacement were offered the choice of having

the knee arthroplasty done with the accelometry based alignment or with the

conventional jigs. If they opted to use the accelometry based device, the surgery

was performed using the technique described. Bilateral knee replacements were

done with a single kit

o . If they preferred that the Orthoalign jigs were not used, the surgery was

performed using the conventional intra and extra medullary jigs.

o The two groups were not randomised.

39

Detailed diagrammatic algorithm of the Study.

40

Inclusion criteria

o All patients who presented with end stage osteoarthritis of the knees between July

2016 and July 2017 to the Orthopaedic Unit 2 for a knee replacement.

Exclusion criteria

Concomitant Hip/femur pathologies

Revision knee arthroplasty/complex primary arthroplasty involving the use of

augments/stems

Sample Size

A sample size of 30 patients in each cohort was calculated to provide appropriate power to

detect a 25% improvement in accuracy between the two groups.

41

Statistical Methods:

Data entered using EPIDATA software and screened for outliers and extreme

values using Box-Cox plot and histogram (for shape of the distribution). Summary

statistics provided for reporting demographic and clinical characteristics. T-test will

be used for analysis of continuous data with group and Unilateral/Bilateral. Chi-square

performed for categorical variables with group. Differences will be considered

significant at p<0.05. All the statistical analysis was performed using SPSS 18.0.

This study was accepted by the Institutional Review Board, Christian Medical

College, and Vellore.

42

Preoperative evaluation.

Included a full length stitch radiograph of bilateral lower limbs in the antero-

posterior plane, and a lateral view of the knee. For all AP radiographs, care was taken

to ensure the patellae was facing forward to control for rotation. For standardization

during documentation, positive values indicated a varus alignment, and negative

values indicated a valgus alignment.

The mechanical lateral distal femoral angle (mLDFA) and the anatomical lateral distal

femoral angle (aLDFA) were digitally measured using the preoperative radiographs

with the PACS imaging system. Measurement of the mLDFA and aLDFA was

originally described by Deakin et al. The mLDFA was defined as the lateral angle

between the femoral mechanical axis and a line tangent to the most distal aspects of

the medial and lateral femoral condyles – the knee joint line. The aLDFA was defined

as the lateral angle between the femoral anatomical axis and the joint line. The

preoperative difference between the mLDFA and aLDFA was calculated and recorded

for each patient. The difference between the mLDFA and aLDFA represents the

valgus angle for each individual patient.

43

Figure with aLDFA and mLDFA

44

The lower extremity mechanical axis is defined as the angle formed between a line

drawn from the center of the femoral head, to the central and most distal point of the

intercondylar notch of the femur, and a second line drawn between the center of the

tibial plateau and the center of the tibial plafond.

Figure with Pre-operative measurement of mechanical axis of left lower limb.

45

Post-operative assessment.

Radiological evaluation:

The radiological parameters assessed after the surgery included - .

Alignment of the tibial component in the coronal plane.

Posterior slope of the tibial cut in the sagittal plane.

Alignment of the femoral component in the coronal plane.

The lower extremity mechanical axis

Proximal Tibial implant position in Coronal Plane:

This is measured using the stitch view. A line is drawn joining the medial and lateral margins

of the talar subcondral surface (A). Another line joining the medial and lateral aspect of the

tibial plateau is drawn (B). A line joining the midpoints of these two lines represents the

mechanical axis of the tibia.

Another line is drawn connecting the medial and lateral aspects of the distal margins of the

tibial tray and a line perpendicular to this is drawn from the midpoint (C).

The angle between this line and the Mechanical axis of the tibia forms the mechanical

varus/valgus alignment of the tibia. For convention, negative values indicate valgus

alignment and positive values represent varus deformity (e.g. −0.8° represents a 0.8°

valgus malposition of the tibial implant relative to the mechanical axis).

46

Tibial Implant placement in Coronal plane.

47

Tibial implant in sagittal plane.

Lateral knee to ankle radiographs are taken. First, a line is drawn connecting the mid

points of the tibial shaft 10 and 20 cm from the joint line, A line ‘A’ is drawn

perpendicular to that line. Another line ‘B’ - tangential to the under surface of the

tibial component is then traced. The angle between the lines A and B is the posterior

slope of the tibial component. The measured angle is recorded with a positive value

when a posterior slope is present, and a negative value if an anterior slope is present.

48

1. Distal Femoral component placement

The angle between the femoral mechanical axis (A) and a line (B) tangential to the

most distal aspects of the medial and lateral femoral condyles represents the

mechanical varus/valgus alignment of the femoral component. A negative number

represents valgus and a positive number indicates varus.

49

To draw the mechanical axis, a line is drawn from the centre of the femoral head to

the centre of the intercondylar notch.- To draw the anatomic axis, a mark is made at

the midpoint of the shaft, 10cm from the joint line, and another similar point is made

10cm proximal to that. A line joining the two points represents the anatomic axis- and

this passes though the point of entry of the intramedullary alignment rod

preoperatively. The difference between the two angles is the valgus angle of the

femur.

50

2. The postoperative lower extremity mechanical axis

is defined as the angle formed between a line drawn from the center of the

femoral head, to the central and most distal point of the intercondylar notch of

the femur (line A), and a second line drawn between the center of the tibial

plateau and the center of the tibial plafond (line B).

51

The number of “outliers” in each group will be determined. Outliers are defined as

1. A tibial or femoral component alignment outside of 2° of perpendicular to the

mechanical axis in the coronal plane,

2. A tibial posterior slope outside of 2° from the intended slope ( CR knee used)

in the sagittal plane, or

3. An overall lower extremity mechanical alignment outside of 3° of a neutral

mechanical axis,

For individual component alignment, a deviation of greater than 2° was selected as an

“outlier” based on prior studies assessing the accuracy of component alignment in

TKA(24,25). Similarly, a deviation of greater than 3° from a neutral mechanical axis

for the lower extremity mechanical alignment was selected based on prior

studies(24,25). The ability to achieve the surgeon’s intraoperative goal was assessed

by measuring the difference between the intraoperative goal recorded and the

postoperative radiographic alignment.

52

Other parameters assessed included.

1. Time of surgery ( tourniquet time)

2. Haemoglobin change post op

3. Need for transfusion.

Methods to minimize bias:

The angle on the radiographs were read by 2 investigators and where

there was a discrepancy- there was a discussion to reach a consensus.

Both investigators were blinded as to the method of navigation used to

decrease bias.

Data Source and Management:

Demographic data was based on the patient history.

Patients’ Xrays were obtained from the department of Radio diagnosis, Christian

Medical College, Vellore. The measurement of angles were done using Centricity

Enterprise software (Version 3.0)

53

Data Collection

Patients who satisfied the inclusion criteria were taken into consideration. The

inpatient and outpatient records of the respective patients were accessed and contact

numbers were obtained. The details of the study were explained and all queries were

clarified. An informed consent was obtained and the patients were examined and the

data was entered in the preform attached.

54

Results

55

Results:

A total of 61 patients were included in the study after satisfying the inclusion

criteria. 30 patient were in the OrthAlign cohort and 31 patients in the conventional

cohort.

Regarding the sex distribution of the patients, there was a relatively even

distribution of the sexes among the two groups. There were 16.7% males and 83.3%

females in the in the OrthAlign cohort as compared to 25.8% males and 74.2%

females in the conventional cohort.

56

The demographic data of the study population is elaborated in table below

Table 1:

OrthAlign Cohort Conventional

Cohort P-Values

Gender

Male

Female

5 (16.7%)

25 (83.3%)

8 (25.8%)

23 (74.2%)

0.38

Side

Right

Left

14 (46%)

16 (54%)

18 (58.1%)

13 (41.9%)

0.53

Age

Mean (SD)

Median (IQR)

59.73 (5.73)

56 (55,64)

59 (6.80)

59 (53,65)

0.66

Unilateral

Bilateral

5

25

(13 patients with 1

patient only one

knee assessed)

9

22

(12 patients with 2

patients only 1 knee

assessed

57

The mean age of the study population in the OrthAlign cohort was 59.73 (SD - 5.73)

as compared to the conventional cohort 59 (SD - 6.80).

59.73 59

0

10

20

30

40

50

60

70

Orth Align Conventional Cohort

Year

sMean Age (Years)

58

The OrthAlign cohort had 5 patients who underwent unilateral TKA and 13 patients

who underwent bilateral TKA, this included 1 patients who had bilateral knee

replacement done--but only one knee was taken for the study as the post op Xrays

were not satisfactory. In the conventional alignment cohort, there were 9 unilateral

TKA and 12 bilateral TKA.- this included 2 patients who had bilateral knee

replacement done--but only one knee was taken for the study as the post op Xrays

were not satisfactory

5

9

13

12

0

2

4

6

8

10

12

14

OrthAlign Conventional Cohort

Unilateral vs Bilateral TKA (Number of Patients)

Unilateral Bilateral

59

Table 2:

OrthAlign Cohort

Conventional Cohort

P- Value

Preoperative Mechanical

Axis

Mean(SD)

Median (IQR)

11.56° (6.48)

12.2° (7.87, 15.65)

10.53° (6.66)

11.1° ( 7.3, 16.9)

0.820

PostOperative Mechanical Axis

Mean(SD)

Median (IQR)

Range

2.27° (2.47)

2.35° (1.00, 4.10)

-4.4° to 6.4°

3.47 ° (3.48)

3.60° ( 1.80, 5.20)

-5.0° to 12°

0.14

PostOperative Femoral Component

Varus/Valgus

Mean(SD)

Median (IQR)

1.60° (2.06°)

1.95° (0.65, 2.80)

1.46° (2.15)

1.30° ( 0.20, 2.80)

0.28

PostOperative Tibial component

Placement (Coronal Plane)

Mean(SD)

Median (IQR)

0.69° (1.53)

0.75 (-0.43, 1.90)

1.87° (1.72)

1.90 (1.40, 2.80)

0.004

60

PostOperative Tibial Component placement (Sagittal

Plane)

Mean(SD)

Median (IQR)

0.93° (2.21)

0.60° (-0.18, 3.15)

4.43° (3.04)

4.10° (2.20, 6.50)

<0.001

Preoperative mechanical axis deviation

The mean preoperative mechanical axis was found to be 11.56 (SD - 6.48) in the

OrthAlign group and 10.53 (SD 6.66) in the conventional cohort group. This

difference was not statistically significant.

11.56

10.53

0

2

4

6

8

10

12

14

OrthAlign Conventional Cohort

Deg

rees

Preoperative Mechanical Axis

61

Postoperative mechanical axis deviation

All patients received the appropriate radiographs post operatively (Standing Hip-

Ankle stitch view –AP, Lateral view of tibia).

The mean post-operative mechanical axis was found to be 2.27 degrees (SD 2.47) in

OrthAlign cohort as compared to 3.47 degrees (SD 3.48). This difference was not

statistically significant.

2.27

3.47

-1

0

1

2

3

4

5

6

7

8

OrthAlign Cohort Conventional Cohort

DEG

REE

S

Mean Postoperative Mechanical Axis

62

Postoperative Femoral Component placement

Similarly no significant difference was noticed in the mean Femoral Component

alignment between the two groups with OrthAlign cohort having a mean error of 1.60

degrees (SD 2.06) and 1.461 degrees (SD 2.15) in the conventional cohort.

1.61.461

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4


DEG

REE

S

Mean Postoperative Femoral Component placement

63

Postoperative Tibial Component placement in Coronal Plane

There was a significant difference between the mean tibial component alignment in

the coronal plane for the OrthAlign 0.69 degrees (SD 1.53) and conventional cohort

1.87 degrees (SD 1.72) (p-value 0.004).

0.69

1.87

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4


DEG

REE

S

Mean Postoperative Tibial Component placement in Coronal Plane

64

Postoperative Tibial Component placement in Sagittal Plane

Similarly regarding the Posterior Slope in tibial component, a significant difference

was observed between mean posterior slopes of the two groups. Orthalign cohort 0.93

degrees (SD 2.21) compared to conventional cohort 4.43 degrees (SD 3.04) with a p -

value <0.001),

0.93

4.426

-2

-1

0

1

2

3

4

5

6

7

8


DEG

REE

S

Mean Postoperative Tibial Component placement in Sagittal Plane

65

Table 3:

OrthAlign Cohort

Conventional Cohort

P- Value

N % N %

Post Operative Mechanical Axis

Varus/valgus <=3° >3°

18 12

60% 40%

14 17

45.1% 54.9%

0.373

Femoral Component

Varus/Valgus

<=2° >2°

16 14

53.3% 46.7%

21 10

67.7% 32.3%

0.370

Tibial component Varus/Valgus

<=2° >2°

23 7

76.7% 23.3%

16 15

51.6% 48.4%

0.077

Tibial Component

Posterior Slope <=2° >=2°

17 13

56.7% 33.3%

7 24

22.6% 77.4%

0.014

66

Outliers in mechanical axis

60 % of the patients in the OrthAlign cohort were found to have a post-operative

mechanical axis ≤ 3° as compared to 45.1% in the conventional cohort (p – value

0.373). Outliers were 40% in the Orthalign and 54.9% in the conventional group. This

difference was not statistically significant.

60%

45.10%

0%

10%

20%

30%

40%

50%

60%

70%


Postoperative mechanical Axis ≤ 3°

67

Outliers in Femoral Component position

With regards to the number of outliers in the femoral component placement, only

53.3% of patients in the OrthAlign cohort had a femoral component alignment ≤ 2°

compared to 67.7 % in the conventional cohort (p- value - 0.370), Outliers were

46.7% in the Orthalign and 32.3 % in the conventional group. This difference was not

statistically significant.

53.30%

67.70%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%


Femoral Component Varus/Valgus <=2°

68

Outliers in Tibia Component position in coronal plane

Regarding the number of outliers, there was no significant difference between the two

groups where 76.7% of Orthalign cohort were within ≤ 2° as compared to 51.6% in

the conventional cohort (p-value 0.077). Outliers were 23.3 % in the Orthalign and

48.4 % in the conventional group. This difference was not statistically significant.

76.70%

51.60%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%


Tibial component Varus/Valgus <=2° (Coronal Plane)

69

Outliers in Tibia Component position in the sagittal plane

Comparing the number of outliers for tibial component placement in the sagittal plane,

56.7% of Orthalign cohort were observed to be ≤ 2° as compared to 22.6% in the

conventional cohort (P- value 0.014). Outliers were 43.3% in the Orthalign and 77.4

% in the conventional group. This difference was statistically significant.

56.70%

22.60%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%


Tibial component Varus/Valgus <=2° (Sagittal Plane)

70

Table 4:

OrthAlign Cohort

Conventional Cohort

P- Value

Mean Tourniquet

times (Minutes)

Mean (SD) Median (IQR)

64.67 ( 11.03) 64.50(58.50,71.00)

74.06 ( 16.3) 75.00 (64.00, 85.00)

0.011

Haemoglobin drop

Unilateral


Bilateral


-0.93 (0.42) -0.87 (-1.3, -0.58)

-1.7 (1.2) -1.7 (-2.7, -1.1)

-1.85 (1.31) -1.8 (-3.0, -0.53) -2.33 (1.67) -2.60 (-3.8, -0.83)

0.20 0.538

Blood transfusion.

Only 2 patients (Bilateral TKA in conventional cohort) had to receive a post-operative

blood transfusion, both had alignment using the conventional alignment. None of the

patients who had Orthoalign required blood transfusion. This however was not

significantly different between the two groups. (P-value of 0.426.)

71

Surgery Time (Tourniquet time)

The mean tourniquet time found to be significantly shorter in the Orthalign cohort

(64.67 minutes (SD 11.03)) as compared to the conventional cohort (74.06 (SD 16.3)

by 10 minutes with a p- value of 0.011.

Haemoglobin drop.

The mean post-operative haemoglobin drop among the unilateral TKA in both cohorts

was -0.93 (SD 0.42) (Orthalign) and -1.85 (SD 1.31) (conventional cohort)

respectively. Furthermore, among the bilateral TKA the mean post-operative

haemoglobin drop for the OrthAlign cohort was -1.7 (SD 1.2) and -2.33 (SD 1.67) for

64.67

74.06

0

10

20

30

40

50

60

70

80

90

100


Min

ute

s

Mean Tourniquet Times

72

the conventional cohort. There was no significant difference between the two cohorts

in relation to haemoglobin drop with a p- value of 0.20 for the unilateral and p-value

of 0.538 for the bilateral TKAs.

Although the difference between the two cohorts are not statistically significant, they

are clinically significant as the conventional cohort had twice the post-operative

haemoglobin drop in both unilateral and bilateral cases as compared to the OrthAlign

cohort. This could be due to the fact that unlike the conventional analogue alignment

jigs, there is no need to place an intramedullary femoral alignment rod in OrthAlign

system. Since there is no violation of the femoral canal in the OrthAlign system there

is less blood loss.

Blood transfusion.

This difference in haemoglobin drop was also reflected in the need for transfusion.

Only 2 patients (Bilateral TKA in conventional cohort) had to receive a post-operative

blood transfusion, both had alignment using the conventional alignment. None of the

patients who had Orthoalign required blood transfusion. This however was not

significantly different between the two groups. (P-value of 0.426.)

73

Discussion

74

Discussion:

Component malposition and mechanical limb alignment has

been recognised as important factors in the implant survival of total knee arthroplasty

(9). Unfortunately conventional methods of alignment using extra medullary jigs have

been found to have limited (26) as compared to computer assisted surgical techniques

(CAS) (21) (25). The CAS systems are typically CT-guided, image based or imageless

and require the use of a large console along with infra-red emitting or reflecting

trackers. Although CAS systems have been demonstrated to be more accurate in

implant placement, there are many drawbacks including the cost of use, line of sight

issues, a steep learning curve etc.

In recent years, there have been numerous encouraging reports of accelerometer Hand

held navigation systems providing accurate placement of femoral and tibial

components as well as the overall mechanical alignment of the operated limb(29)(27).

Our study has demonstrated that the accelerometer based handheld navigation system

(OrthAlign) does not decrease the incidence of outliers in tibial resection in coronal

plane with only 76.7% of knees in the OrthAlign cohort within ≤ 2° as compared to

51.6% in the conventional cohort (p-value 0.077) but however, it does so significantly

in sagittal plane where 56.7% of knees in the OrthAlign cohort vs. 22.6% in the

conventional cohort (p- value 0.014).

75

With regards to the mean error in tibial component placement, the OrthAlign cohort

demonstrated a statistically significant decrease in both planes.

In the coronal plane the mean malposition was 0.69 degrees (1.53) (OrthAlign)

compared to 1.87 degrees (1.72) (conventional cohort) with a p-value of 0.004. In the

sagittal planes the mean error was 0.93 degrees (2.21) for OrthAlign cohort as

compared to 4.43 degrees (3.04) in the conventional cohort with a p value of <0.001.

This finding of improved tibial component placement is consistent with multiple

studies on the same subject. However the femoral component placement and overall

mechanical axis were found to be less accurate.

In a prospective study by Nam et all, of 39 TKAs performed by one surgeon, 93.8% of

TKA had a mechanical axis of ±3°, 96% of tibial components were within ±2° of goal,

and 95.8% of femoral components were within ± 2° (28).

Denis Nam Et all (19) conducted a randomised control trial that compared the

accelerometer based hand held navigation system (OrthAlign) with the conventional

extra medullary guides. They reported significant reduction of the number of

“outliers” for tibial component alignment in both the coronal and sagittal planes.

In their study mean tibial component varus/valgus alignment was -0.6° ± 0.9° in the

OrthAlign cohort versus -0.9° ± 1.6° in the conventional cohort (P = 0.26) .

Comparing this finding to our data where we found that the mean error in tibial

component alignment in the OrthAlign cohort, was 0.69 (SD 1.53) and 1.87 (SD 1.72)

in the conventional cohort with a p- value of 0.004.

76

Although their finding was not statistically significant, they found that 95.7% of tibial

components in the OrthAlign cohort were within 2° of perpendicular to the tibial

mechanical axis, versus 68.1% in the conventional cohort (P value- 0.001). In our

study the number of knees with tibial alignment error ≤ 2 ° was 76.7% in the

OrthAlign group and 51.6% in the conventional group (p value - 0.077)

With regards to post-operative mechanical axis, they reported that 89.4% of OrthAlign

cohort and 74.5% of conventional cohort (p value- 0.10). In our study we found that

60% of OrthAlign cohort and 45.1% of the conventional cohort were with ≤3°.

With regards to the Posterior slope or proximal tibial component alignment in sagittal

plane, they reported that 95.0 % of the OrthAlign cohort and 72.1% of the

conventional cohort were within ≤2° with a p- value of 0.007. In our study, we did

find that there was a significant difference in the number of outliers between the two

groups, however the percentage of tibial components within range were lower as

compared to the above study with only 56.7% of OrthAlign and 22.6% of

conventional cohort within range.

Denis Nam et all (28) also published a case series of 32 patients who underwent Total

knee arthroplasties done using the OrthAlign system focusing only on tibial

component placement. They reported that the mean postoperative radiographic

alignment of the tibial component was −0.6° ± 0.9° with 97.6% of the tibial

components were placed 90° ± 2° to the mechanical axis, and 100% of the

components were placed 90° ± 3° to the mechanical axis.

77

With regard to the accuracy between the intraoperative reading provided by the

OrthAlign system and the postoperative tibial component posterior slope, the mean

absolute difference was 1.0° ± 0.7°, with 92.6% of the implants being positioned

within 2° of the intraoperative alignment recorded. In our study, the number of knees

within range (≤2°) was relatively less (76.7%)

Eddie H. Huang et all carried out a prospective, single-arm study of patients

undergoing an elective primary TKA using a handheld navigation system for distal

femoral and tibial resection and positioning (29). In the study 17% of knees had

greater than 3° of coronal malalignment, the mean femoral coronal alignment was 0.8°

± 2.2° varus and 13% of the femoral components were placed in greater than 3° of

coronal malalignment. The mean tibial coronal alignment was 0.09° ± 1.4° varus with

3.8% of tibial components were placed in greater than 3° of coronal malalignment.

The mean tibial slope was 3.33° ± 1.8° with 5.7% of tibial components were placed in

greater than ± 3° of targeted tibial posterior slope.

In our study, with regards to the conventional cohort, the finding of 48.4% and 77.4%

outliers in the tibial implant placement in the coronal and sagittal plane respectively.

This is comparable to a prospective, randomized study of 135 TKAs comparing tibial

IM and EM alignment guides, Reed et al demonstrated correct tibial varus/valgus

alignment to be present in only 65% of patients in the Extra medullary cohort(21).

78

The finding of significant decrease in tourniquet time in the OrthAlign cohort (64.67

(11.03) vs. 74.06 (16.3)) as compared to the conventional cohort was unanticipated.

This finding is a testament to the simplicity, user friendliness and easy learning curve

of the OrthAlign system.

79

Limitations

80

Limitations:

The additional cost of the OrthAlign system was significant (Approximately 30,000/-).

Therefore randomization was not feasible and patients were given the choice of using

OrthAlign or conventional extra medullary alignment systems. A fully randomised

control trial would be a more thorough approach to tackle this research question.

Additional analysis using functional scores in combination with a randomised control

trial would provide a better understanding of patient satisfaction and function.

The radiological analysis was conducted with the use of standing stitch view and

lateral tibial radiographs. If the radiographs are not of optimum quality, there is room

for parallax errors which may lead to skewed readings. A solution to this problem may

be the use of other technologies like a CT to provide more accurate readings.

However, computed tomography has several disadvantages, including radiation

exposure, cost, and artefact surrounding the implants, and it is not used for routine

follow-up in the clinical setting.

81

Conclusion

82

Conclusion:

The overall post op mechanical alignment was better in the orthalign group

as compared to the mechanical alignment group although the difference was

not significant

There was a significant improvement in the tibial component alignment in

the coronal plane in the Orthoalign group as compared to the mechanical

alignment group

There was a significant improvement in the mean tibial component

alignment in the saggital plane with the Orthalign cohort compared to

conventional cohort

The post-operative femoral alignment was better in the mechanical

alignment group as compared to the Orthalign group – but the difference

was not significant.

The number of outliers who had a post op mechanical axis alignment >3

degrees; and the outliers who had tibial alignment in coronal plane >2

degrees were more in those who had conventional alignment methods-

though the difference was not statistically significant.

The number of outliers who had a post op tibial alignment in sagittal plane

>2 degrees were significantly more in those who had conventional

alignment methods than those who used Orthalign

83

The number of outliers who had a post op femoral alignment in coronal

plane >2 degrees were more in those who used the Orthalign method-

though the difference was not statistically significant.

The tourniquet time was significantly less in the Orthoalign group as

compared to the mechanical alignment group.

The blood loss (drop in haemoglobin) was less in the Orthalign cohort,

though the difference was not significant

The blood transfusion rates was less in the Orthalign cohort, though the

difference was not significant

This study demonstrates that accelerometer-based navigation can significantly reduce

the malalignment in proximal tibial cuts in TKA although there was no significant

decrease in the number of outliers in all radiological measurements with the exception

of the tibial component alignment in sagittal plane. However, when compared with

conventional IM alignment systems, it has several advantages. The OrthAlign system

does not rely on assumptions based off the mechanical and anatomical axes of the

femur and is able to register the hip center of rotation and femoral mechanical axis. In

addition, it does not require violation of the IM canal. Therefore, the OrthAlign

system successfully combines the benefits of large-console CAS systems, while

avoiding the disadvantages of conventional IM femoral

alignment systems. This system may have a key role to play in the future of complex

total knee arthroplasty and eventually may find acceptance as an essential part of the

workflow of routine total knee arthroplasty.

84

Bibliography

85

Bibliography

1. 1. Solomon L., Warwick D., Nayagam S. 9th ed. 2010. Apley’s System of Orthopaedics and Fractures; pp. 85–86.

2. Guccione AA, Felson DT, Anderson JJ, Anthony JM, Zhang Y, Wilson PW, et al. The effects of specific medical conditions on the functional limitations of elders in the Framingham Study. Am J Public Health. 1994 Mar;84(3):351–8.

3. Raeissadat SA, Rayegani SM, Hassanabadi H, Fathi M, Ghorbani E, Babaee M, et al. Knee Osteoarthritis Injection Choices: Platelet- Rich Plasma (PRP) Versus Hyaluronic Acid (A one-year randomized clinical trial). Clin Med Insights Arthritis Musculoskelet Disord. 2015;8:1–8.

4. Moisio K, Chang A, Eckstein F, Chmiel JS, Wirth W, Almagor O, et al. Varus-valgus alignment: reduced risk of subsequent cartilage loss in the less loaded compartment. Arthritis Rheum. 2011 Apr;63(4):1002–9.

5. Anderson KC, Buehler KC, Markel DC. Computer assisted navigation in total knee arthroplasty: comparison with conventional methods. J Arthroplasty. 2005 Oct;20(7 Suppl 3):132–8.

6. Blakeney WG, Khan RJK, Wall SJ. Computer-assisted techniques versus conventional guides for component alignment in total knee arthroplasty: a randomized controlled trial. J Bone Joint Surg Am. 2011 Aug 3;93(15):1377–84.

7. Brooks P. Seven cuts to the perfect total knee. Orthopedics. 2009 Sep;32(9).

8. Luo C-F. Reference axes for reconstruction of the knee. Knee. 2004 Aug;11(4):251–7.

9. Scott W. Kinematic Alignment In Total Knee Arthroplasty. Insall & Scott Surgery of the Knee. 5th ed. Ch. 121; 1255–1268. Churchill Livingstone: 2012.

10. Howell SM, Howell SJ, Kuznik KT, Cohen J, Hull ML. Does a kinematically aligned total knee arthroplasty restore function without failure regardless of alignment category? Clin Orthop Relat Res. 2013 Mar;471(3):1000–7.

11. Ritter MA, Faris PM, Keating EM, Meding JB. Postoperative alignment of total knee replacement. Its effect on survival. Clin Orthop Relat Res. 1994 Feb;(299):153–6.

12. Mason JB, Fehring TK, Estok R, Banel D, Fahrbach K. Meta-analysis of alignment outcomes in computer-assisted total knee arthroplasty surgery. J Arthroplasty. 2007 Dec;22(8):1097–106.

86

13. Computer-assisted navigation in total knee replacement: results of an initial experience in thirty-five patients. - PubMed - NCBI [Internet]. [cited 2017 Jul 24]. Available from: https://www.ncbi.nlm.nih.gov/pubmed/12479344/

14. Bae DK, Song SJ. Computer Assisted Navigation in Knee Arthroplasty. Clin Orthop Surg. 2011 Dec;3(4):259–67.

15. Natural distribution of the femoral mechanical-anatomical angle in an osteoarthritic population and its relevance to total knee arthroplasty. - PubMed - NCBI [Internet]. [cited 2017 Jul 24]. Available from: https://www.ncbi.nlm.nih.gov/pubmed/21353567

16. Kim K-I, Ramteke AA, Bae D-K. Navigation-assisted minimal invasive total knee arthroplasty in patients with extra-articular femoral deformity. J Arthroplasty. 2010 Jun;25(4):658.e17-22.

17. Millar NL, Deakin AH, Millar LL, Kinnimonth AWG, Picard F. Blood loss following total knee replacement in the morbidly obese: Effects of computer navigation. Knee. 2011 Mar;18(2):108–12.

18. Novak EJ, Silverstein MD, Bozic KJ. The cost-effectiveness of computer-assisted navigation in total knee arthroplasty. J Bone Joint Surg Am. 2007 Nov;89(11):2389–97.

19. Nam D, Cody EA, Nguyen JT, Figgie MP, Mayman DJ. Extramedullary guides versus portable, accelerometer-based navigation for tibial alignment in total knee arthroplasty: a randomized, controlled trial: winner of the 2013 HAP PAUL award. J Arthroplasty. 2014 Feb;29(2):288–94.

20. Bugbee WD, Kermanshahi AY, Munro MM, McCauley JC, Copp SN. Accuracy of a hand-held surgical navigation system for tibial resection in total knee arthroplasty. Knee. 2014 Dec;21(6):1225–8.

21. Reed MR, Bliss W, Sher JL, Emmerson KP, Jones SMG, Partington PF. Extramedullary or intramedullary tibial alignment guides: a randomised, prospective trial of radiological alignment. J Bone Joint Surg Br. 2002 Aug;84(6):858–60.

22. Nam D, Dy CJ, Cross MB, Kang MN, Mayman DJ. Cadaveric results of an accelerometer based, extramedullary navigation system for the tibial resection in total knee arthroplasty. Knee. 2012 Oct;19(5):617–21.

23. Iorio R, Mazza D, Drogo P, Bolle G, Conteduca F, Redler A, et al. Clinical and radiographic outcomes of an accelerometer-based system for the tibial resection in total knee arthroplasty. Int Orthop. 2015 Mar;39(3):461–6.

24. Nam D, Weeks KD, Reinhardt KR, Nawabi DH, Cross MB, Mayman DJ. Accelerometer-based, portable navigation vs imageless, large-console computer-

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assisted navigation in total knee arthroplasty: a comparison of radiographic results. J Arthroplasty. 2013 Feb;28(2):255–61.

25. Huang EH, Copp SN, Bugbee WD. Accuracy of A Handheld Accelerometer-Based Navigation System for Femoral and Tibial Resection in Total Knee Arthroplasty. J Arthroplasty. 2015 Nov;30(11):1906–10.

26. Dennis DA, Channer M, Susman MH, Stringer EA. Intramedullary versus extramedullary tibial alignment systems in total knee arthroplasty. J Arthroplasty. 1993 Feb;8(1):43–7.

27. Confalonieri N, Manzotti A, Pullen C, Ragone V. Computer-assisted technique versus intramedullary and extramedullary alignment systems in total knee replacement: a radiological comparison. Acta Orthop Belg. 2005 Dec;71(6):703–9.

28. Nam D, Jerabek SA, Haughom B, Cross MB, Reinhardt KR, Mayman DJ. Radiographic Analysis of a Hand-Held Surgical Navigation System for Tibial Resection in Total Knee Arthroplasty. The Journal of Arthroplasty. 2011 Dec;26(8):1527–33.

29. Nam D, Cross M, Deshmane P, Jerabek S, Kang M, Mayman DJ. Radiographic results of an accelerometer-based, handheld surgical navigation system for the tibial resection in total knee arthroplasty. Orthopedics. 2011 Oct 5;34(10):e615-621.

30. Nam D, Nawabi DH, Cross MB, Heyse TJ, Mayman DJ. Accelerometer-based computer navigation for performing the distal femoral resection in total knee arthroplasty. J Arthroplasty. 2012 Oct;27(9):1717–22.

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ANNEXURES

Patient Information Sheet

Consent Forms

Clinical Research Forms

IRB and Fluid Grant Acceptance form

Thesis Data

89

Patient Information Sheet:

90

91

92

93

94

95

96

97

Informed Consent Forms:

98

99

100

101

102

Clinical Research Form ( Proforma)

Radiological and Clinical evaluation of handheld navigation system for total knee arthroplasty:

Serial No-

Name - Age- Sex-

Preoperative Diagnosis-

Date of surgery:

Procedure details- uni/bilateral

Implant used-

Ortho align- Yes/No

Preoperative Measurements-

Femur

mLDFA -

aLDFA-

Valgus angle:

Tibia-

For ortho line -Predetermined posterior slope-

For conventional alignment - native slope from X ray

Postoperative measurement-

Femur-

mLDFA

Mechanical Varus/Valgus (90-Mldfa)

Outlier (>2degrees of malalignment)- Yes/No

Tibia-

Coronal Plane mechanical varus/valgus angle-

Mechanical Varus/Valgus (90-mechanical angle)


103

Posterior slope-

Actual slope

Difference from intended slope:


Lower extremity mechanical axis

Outlier (>3 degrees of malalignment)- Yes/No

Jointline –……………… mm from fibular head

Change in joint line (+ for raised and – for lowered jt line)

Clinical Evaluation:

Blood loss in drain

Time of tourniquet.

Blood transfusion.

Preop Hb

Post op Hb before transfusion

Change in Hb

104

IRB and Fluid Grant approval

105

106

107

108

Patient data

109

110

Documents

Radiological evaluation of OrthAlign -a novel handheld ...repository-tnmgrmu.ac.in/9511/1/220201118abhishek_jirel.pdf · Dr. Vrisha Madhuri, Dr. Thomas Palocaren, Dr. Abhay, Dr. Alfred