1 The Zimmer Institute The Zimmer® MIS™ Anterolateral Hip Procedure A Muscle-Sparing Approach to THA

1

The Zimmer Institute

The Zimmer® MIS™ Anterolateral Hip Procedure

A Muscle-Sparing Approach to THA

2


Objectives

• Discuss the history of minimally invasive surgery in terms of evolution, definitions, approaches, and classification schemes

• Identify the unique characteristics of the Zimmer MIS Anterolateral THA procedure

• Discuss in detail the stages and key elements of the Zimmer MIS Anterolateral THA surgical procedure

• Define the Five Acts of leg positioning and describe how they relate to the various stages of the surgical procedure

3


Objectives (cont.)

• Discuss clinical data obtained from procedure to date

• Define the advantages and disadvantages of the Zimmer MIS Anterolateral THA procedure as they relate to THA in general

• Identify and discuss key concerns in the overall continuum of care related to the Zimmer MIS Anterolateral THA procedure

4


Minimally Invasive Surgery: History, Evolution, Definitions, and Approaches

5


Minimally Invasive Surgery:Evolution in THA Procedures

• Maximally invasive 60s/70s

• Moderately invasive 80s/90s

• Minimally invasive Turn of the century

6


Maximally Invasive Surgery

• Typically Provides:

Wide Exposure

Neurovascular protection

Confident implant placement

With this incision I can do every hip:I can expose it,

I can see it,I can teach it

(C. S. Ranawat, CCJR 2003)

7


What is the Minimally Invasive THA?

• Length of Incision?

• Length of capsule incision.

• Amount of muscle trauma!

• Amount of bone loss!

8


Minimally Invasive THA Classification

Eponymous

• Modified Watson Jones

• Modified Smith Peterson

• Modified Moore

• Keggi/Mears/Röttinger

…does not connote much meaning

9



Proposal

• Direction

• Number of incisions

• Method of deep dissection

10



Direction is the key

• Gluteus Medius is the signpost

• Anterior

• Anterolateral

• Lateral

• Posterior

11



Number of incisions

• Single Incision – acetabular/femoral preparation through one incision

• Two incisions – acetabular preparation through anterior incision and femur preparation through posterior incision

12


Minimally Invasive Surgery THA

Method of Deep Dissection is key

• Do you divide or go between the muscles and tendons?

Traditional – Cut

Mini Anterolateral – Cut less

MIS Anterolateral – Spare

• Spare: to refrain from doing harmMerriam Webster’s Dictionary

13



Method of Deep Dissection

• Anterior - Muscle Sparing

• Anterolateral - Muscle Sparing

• Lateral - Muscle Cutting

• Posterior - Muscle Cutting

• Two-incision - Muscle Sparing

14


Introduction to the Zimmer MIS Anterolateral THA Procedure

15


The MIS Anterolateral Approach

• A single incision

• Muscle sparing approach to the hip

• Interval between the anterior border of the gluteus medius and the posterior border of tensor fascia lata.

• Minimally invasive modification conceived by Heinz Röttinger, M.D. from the Orthopädische Chirurgie München (O.C.M.) Munich, Germany in 2003

Tensor Fascia Lata

Gluteus Medius

16


The MIS Anterolateral Approach – Overview

• Interval between Gluteus Medius and Tensor Fascia LataNo division of any muscle or tendon

• Acetabulum and femur directly visualized

• 8-10 cm incision

• Posterior capsule intact → lower risk of dislocation

17


The MIS Anterolateral Approach – Overview (cont.)

• Extensile - bail out is full Watson Jones exposure

• Acceptable learning curve

• Familiar lateral positioning

• Clear of neurovascular hazards

• Compatible with most contemporary Zimmer implants

18


The MIS Anterolateral Key Principles

• Identification of interval

• Anatomical referencing

• Retraction and mobile window

• Femoral exposure/Extensibility of capsular incision

• Leg positioning

19


MIS Anterolateral Procedure

The Five Leg Positions

1. Skin and Capsular Incisions/Closure

2. Transcapital Neck Cut

3. Definitive Neck Cut

4. Acetabulum

5. Femur

20


Leg Positioning

IncisionsFemoral Side

Acetabular Side

Definitive Osteotomy

1st Femoral Cut

21


Surgical Technique for the Zimmer MIS Anterolateral THA Procedure

22


The MIS Anterolateral Surgical Considerations

• Pre-op Templating

• Table

• Positioning

• Draping

• Incision

• Dissection

• Capsule

• Referencing (intra-operative measurements)

• Neck Osteotomies

• Acetabulum

• Femur

23


Templating

• Measure down from the “Saddle”• Other anatomical references • Lesser trochanter can usually be palpated for cross reference

Greater Trochanter

“Saddle”

Lesser Trochanter

24


Surgical Technique

• Table set up Trumpf Jupiter table or Maquet Skytron table attachments Local custom modification

25


Patient and Table Preparation

• Patient in direct lateral position• Securely held on table• Leg support modified to allow posterior leg

positioning• Surgeon works on anterior side

26


Draping

• Drape can become unstable

• Sterile bag

27


Team Positioning

• Surgeon Anterior

• 1st Assistant Distal/Posterior

• 2nd Assistant Posterior

28


Skin Incision and Intermuscular Interval

29


Skin Incision

• Identify greater trochanter and anterior superior iliac crestExtend incision from anterosuperior aspect of greater

trochanter about 8cm to a point 2-4cm posterior to the ASIS

30


The Interval

Tensor FasciaLata

Gluteus Medius

Approximate incision location

31


The Interval

Tensor Fascia Lata

Gluteus Medius

Head

ASIS

GreaterTrochanter

32


Capsular Exposure• The Instruments

Retractors numbered for ease of use Optimized radius to be gentle to muscle

Retractor 1 Retractor 2

33


The Interval

Gluteus Medius

Tensor Fascia Lata

Capsule

34


Capsulotomy

• A “Z” shaped capsular incision with two flaps is created

Slight internal hip rotation

Neutral to slight hip abduction

Ability to extend lateral capsular incision can be critical to obtaining adequate femoral exposure

T or H shaped capsular incisions are certainly viable options

35


36


Femoral Neck Exposure

• Retractors are replaced inside the capsule

37


Referencing

• The “Saddle”

• Other anatomical references

• Lesser trochanter can usually be palpated for cross reference

“Saddle”

38


First Neck Osteotomy

• Femoral head and neck are taken out in two pieces

• First “neck” cut is in articular portion of femoral head

• Direct blade inferior

• Externally rotate maximally to approximately 60 or to allowable range of motion

39


Neck-Head Disassociation

• Place Cobb elevator in the first neck cut

• Move leg into extension and external rotation and lever with Cobb elevator to disassociate femoral neck from residual head and deliver neck into incision

• Neck will now be parallel to the floor

40


Definitive Femoral Neck Cut(s)

• Hip and leg are rotated 90 externally with thigh parallel to the floor

• Slight hip flexion may help and saw must be adjusted accordingly

• Retractors placed more distal on neck

• Osteotomy - Identify referencesOblique portion based on

preoperative plan for angle and position

Horizontal portion medial to trochanter

41


Femoral Head Removal

• Proximal positioned first osteotomy facilitates easier removal

42


43


Acetabular Exposure

• The Instruments Retractors

Retractor 1 Retractor 3

44


Acetabular Exposure

• Retractor Placement 4 o’clock and 8 o’clock positions

Retractor 1

Retractor 3

45


Acetabular Preparation

• The Instruments

Offset reamer handle, low profile reamers and offset cup positioner

46


Acetabular Preparation• Reaming

Position handle superiorly with flat portion of low profile reamer resting on superior rim of acetabulum

Rotate reamer handle distally and position reamer Hip flexion and abduction can facilitate insertion

47


Acetabular Preparation

• Acetabular implant

48


49


Femoral Exposure - Leg Position

• Foot and leg in a bag on the posterior table

• Deliver the proximal femur into the incision for instrumentation

• 20 Extension• 40 Adduction• 90 External Rotation

50


Femoral Preparation

• The Instruments: Angled/offset rasp handles

400 Rasp Handle 300 Rasp Handle

CLS® Rasp Handle

51


Femoral Preparation

• Retractor placementRetractor 3 inferior and

medial to cut femoral neck―Elevates femur―Retracts tensor &

capsule

Retractor 1 lateral to posterior, superior tip of greater trochanter―Retracts abductors

• Remove any residual anterior and lateral capsule at top of neck to deliver femur

Retractor 1

Retractor 3

52


53


54


Wound closure

• Adapting capsule suture• Deep drain 6 – 24 hours• Closure of fascia• Subcutaneous suture• Intracutaneous suture

55


Surgical Recap: The Five Acts of Leg Positioning

56


MIS Anterolateral Procedure

The Five Leg Positions

1. Skin and Capsular Incisions/Closure

2. Transcapital Neck Cut

3. Definitive Neck Cut

4. Acetabulum

5. Femur

57


Leg Positioning

IncisionsFemoral Side

Acetabular Side

Definitive Osteotomy

1st Femoral Cut

58


Skin and Capsular Incision

• Assistant holds leg in neutral to slight hip abduction

• Relaxes abductors to achieve maximum exposure

• Mayo Stand

• Arm Elevator

Position 1

59


Transcapital Neck Cut

• Assistant holds leg in

neutral ab/adduction slight hip flexion external rotation that anatomy

allows

• Foot in bag

• Relaxes iliopsoas

• Provides improved visualization of femoral neck

Position 2

60


Definitive Neck Cut

• Assistant moves leg into

90 External Rotation

• Foot in bag

• Femur parallel to floor

• Tibia perpendicular to floor

• Positions femoral neck parallel to floor to visualize cut

Position 3

61


Acetabulum


Full knee extension Slight external hip rotation

• Slight hip abduction and hip flexion can help insertion and extraction of reamers

Position 4

62


Femur


90 External Rotation 20 Extension 40 Adduction

• Foot in bag

• Tibia perpendicular to floor

• Elevates femur

Position 5

63


Closure

• Assistant moves leg back to initial position

64


Clinical Data Associated With the Zimmer MIS Anterolateral THA Procedure

65


Clinical data

• 2 surgeons (03/03 – 2/05)

• >700 THA

• Bodyweight 74.5 kg (min. 43 kg, max. 134 kg)

• BMI 26 (maximum 42)

• Surgery time 46 minutes

• Retransfusion volume 302 ml (intraoperative to 6 hrs. postop.)

Röttinger, 2005

66


Clinical Experience – Early Results

• >700 patients

Excellent early mobilization

Decreased pain

Excellent abductor function

Excellent standard approach (also for revisions)

Acceptable learning curve

2 days Post-op

Röttinger, 2005

67


Clinical Experience—Complications

• >700 patients

5 postop. periprothetic fractures ― Caused by a particular femoral component

6 greater trochanter fractures― Asymptomatic

2 dislocations of the acetabular component

3 anterior dislocations ― Increased anteversion of acetabular

component (2 revisions)

Röttinger, 2005

68


Greater Trochanteric Fractures

• No dislocation

• No muscle insufficiency

• Likely related to insufficient lateral superior capsular release

Röttinger, 2005

69


Discussion: Advantages, Disadvantages, and the Continuum of Care With the

Zimmer MIS Anterolateral THA Procedure

70


Where does this new approach fit?

Great alternative for surgeons who prefer anterior approaches

• Advantages

Theoretically better early abductor muscle function

Lateral femoral cutaneous nerve and lateral femoral circumflex vessel not in operative field

Acceptable surgical time

No intraoperative x-ray necessary

Acetabulum and femur directly visualized

71



• More Advantages

Familiar lateral positioning

Compatible with many Zimmer implants

Performed through small incision (patient preference)

Viable bail out

72



• For surgeons who prefer posterior approach

Many of the aforementioned features with

New view of hip

Low dislocation rate

Time, experience and well designed studies will tell

Röttinger, 2005

73



• Potential Challenges

New surgeon positioning

May require two surgical assistants

Expect a variable learning curve

Initial risk of complications ―Excessively anteverted cup― Insufficient capsular release

– Varus stem– Greater trochanteric fracture

Obese and very muscular patients still difficult

74


Discussion

• Post-Op Care

• Anesthesia

• ChallengesLeg Position IntervalCapsular IncisionAcetabulumFemur

• Patient Outcomes

75


Conclusions

• This MIS anterolateral approach is intermuscularPotentially little to no delay in rehabPotentially little to no abductor weakness

• Clinical results are encouraging

76


Documents

1 The Zimmer Institute The Zimmer® MIS™ Anterolateral Hip Procedure A Muscle-Sparing Approach to THA