Jurnal 6

CLINICAL ISSUES

Aggressive continuous passive motion exercise does not improve knee

range of motion after total knee arthroplasty

Lan-Hui Chen, Chung-Hwan Chen, Sung-Yen Lin, Song-Hsiung Chien, Jiing Yuan Su,

Chao-Yung Huang, Hui-Yu Wang, Chih-Liang Chou, Tsung-Yu Tsai, Yuh-Min Cheng and

Hsuan-Ti Huang

Aims and objectives. The aim of this study was to evaluate the effects of continuous passive motion on the range of motion,

postoperative pain and life quality of patients undergoing total knee arthroplasty within six months after the operation.

Background. Total knee arthroplasty reduces pain and improves range of motion of the osteoarthritic knee joint. Continuous

passive motion increases postoperative movement, but there is some controversy regarding whether aggressive continuous

passive motion can improve range of motion or life quality, and whether it induces more pain.

Design. A prospective controlled study was conducted in a medical centre in Taiwan from January to December 2006.

Methods. One hundred and seven patients were recruited. The patients underwent the basic rehabilitation protocols (the control

group) or the basic rehabilitation protocols and additional daily use of continuous passive motion for more than six hours per

day (the experimental group). The range of motion, modified Short Form-36 (SF-36) and semi-quantitative visual analogue scale

were recorded.

Results. Range of motion increased from 109� preoperatively to 125� at six months postoperatively in the treatment group and

from 111� preoperatively to 125� at six months postoperatively in the control group. Visual analogue scale decreased from 7Æ78

preoperatively to 0Æ37 at six months postoperatively in the treatment group and from 7Æ92 preoperatively to 0Æ21 at six months

postoperatively in the control group. The SF-36 improved from 3Æ76 preoperatively to 1Æ77 at six months postoperatively in the

treatment group and from 3Æ68 preoperatively to 1Æ83 at six months postoperatively in the control group. There was no

Authors: Lan-Hui Chen, MHA, RN, Clinical Nurse, Department of

Nursing, Kaohsiung Medical University Hospital, Kaohsiung

Medical University, Kaohsiung; Chung-Hwan Chen, MD, Assistant

Professor, Department of Orthopaedics, Kaohsiung Medical

University Hospital, Kaohsiung Medical University, Kaohsiung and

Department of Orthopaedics and Department of Sports Medicine,

Faculty of Medicine, College of Medicine, Kaohsiung Medical

University, Kaohsiung; Sung-Yen Lin, MD, Doctor, Department of

Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung

Medical University, Kaohsiung and Department of Orthopaedics,

Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical

University, Kaohsiung; Song-Hsiung Chien, MD, Assistant

Professor, Department of Orthopaedics, Kaohsiung Medical

University Hospital, Kaohsiung Medical University, Kaohsiung and

Department of Orthopaedics, Faculty of Medicine, College of

Medicine, Kaohsiung Medical University, Kaohsiung; Jiing Yuan

Su, MD, Assistant Professor, Department of Orthopaedics,

Kaohsiung Medical University Hospital, Kaohsiung Medical

University, Kaohsiung and Department of Orthopaedics, Faculty of

Medicine, College of Medicine, Kaohsiung Medical University,

Kaohsiung; Chao-Yung Huang, BSc, RN, Clinical Nurse,

Department of Nursing, Kaohsiung Medical University Hospital,

Kaohsiung Medical University, Kaohsiung; Hui-Yu Wang, BSc, RN,

Clinical Nurse, Department of Nursing, Kaohsiung Medical

University Hospital, Kaohsiung Medical University, Kaohsiung;

Chih-Liang Chou, BSc, Physical Therapist, Department of

Rehabilitation, Kaohsiung Medical University Hospital, Kaohsiung

Medical University, Kaohsiung; Tsung-Yu Tsai, BSc, Physical

Therapist, Department of Rehabilitation, Kaohsiung Medical

University Hospital, Kaohsiung Medical University, Kaohsiung;

Yuh-Min Cheng, MHA, MD, Professor, Department of

Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung

Medical University, Kaohsiung and Department of Orthopaedics,

Faculty of Medicine, College of Medicine, Kaohsiung Medical

University, Kaohsiung; Hsuan-Ti Huang, MD, Assistant Professor,

Department of Orthopaedics, Kaohsiung Medical University

Hospital, Kaohsiung Medical University, Kaohsiung and

Department of Orthopaedics, Faculty of Medicine, College of

Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan

Correspondence: Hsuan-Ti Huang, Assistant Professor, Department

of Orthopedics, Kaohsiung Medical University Hospital, Kaohsiung

Medical University, No. 100, Tzyou 1st Road, Kaohsiung 80708,

Taiwan. Telephone: +886 7 3208209.

E-mail: [email protected]

The first and second authors contributed equally to this work.

� 2012 Blackwell Publishing Ltd

Journal of Clinical Nursing, 22, 389–394, doi: 10.1111/j.1365-2702.2012.04106.x 389

significant difference in range of motion, visual analogue scale and SF-36 between groups at each visit.

Conclusion. With the advances in total knee arthroplasty surgical technique, aggressive continuous passive motion does not

provide obvious benefits.

Relevance to clinical practice. Total knee arthroplasty can alleviate pain and improve range of motion, but aggressive con-

tinuous passive motion does not provide additional benefits.

Key words: continuous passive motion, life quality, osteoarthritis, pain, range of motion, total knee arthroplasty

Accepted for publication: 22 January 2012

Introduction

With the improvements in medical care, life expectancy has

been extended, and with this, more and more older persons

require total knee arthroplasty (TKA) for advanced knee

osteoarthritis. TKA has been proven a successful treatment

for advanced arthritis of the knee (Laughman et al. 1984,

Stern & Insall 1992, Font-Rodriguez et al. 1997, Pavone

et al. 2001, Kelly & Clarke 2002, Huang et al. 2005).

According to publicly available information from the Health

Insurance Bureau, Taiwan, the expenditure for TKA in 2000

was 2Æ63 billion NT dollars, making it the second costliest

medical expenditure. The therapeutic effects of TKA rely on

not only the surgical technique but also the postoperative

rehabilitation protocol.

The main purposes of TKA are to reduce pain and improve

the range of motion (ROM) of the knee joint, thereby

enhancing the patient’s ability to sit down, rise from a sitting

position and climb stairs, and improving quality of life

(MacDonald et al. 2000, Huang et al. 2007). As early

postoperative ROM is an important prognostic factor for

the patient’s ability to walk later (MacDonald et al. 2000), it

is important to achieve the best possible knee ROM while the

patient is in hospital (MacDonald et al. 2000). Thus, the

rehabilitation protocol in the hospital might have consider-

able consequences for the patient in the longer term.

Continuous passive motion (CPM) was first introduced by

Salter (1989) in the 1960s. CPM has been advocated in the

belief that it increases knee ROM (Salter 1989, McCarthy

et al. 1992). An increase in postoperative ROM will be

achieved, although perhaps at the cost of increased postop-

erative pain. Pain in the early postoperative rehabilitation

period will play a deleterious role in recovery by delaying

mobilisation and limiting exercise potential. Therefore, a

proper rehabilitation protocol to optimise ROM may offer

patients great benefits. The aims of the study were to

investigate whether aggressive CPM during hospitalisation

had an effect on pain, knee ROM and quality of life above

the effect of active postoperative physiotherapy in patients

with TKA within six months after operation, and whether

there was any association between knee ROM and quality of

life. We hypothesised (1) aggressive CPM in the early

postoperative period would improve knee ROM, (2) aggres-

sive CPM would induce more pain, and (3) aggressive CPM

would improve quality of life. In this study, we compared the

effect of prolonged CPM in the early postoperative period

with basic rehabilitation protocols, including straight leg

raising training, walking with a walker and ROM at will.

Materials and methods

Study design

This study was a prospective controlled study involving

patients with degenerative osteoarthritis who had received

TKA for the first time. The patients were allocated into two

groups with two different postoperative exercise regimes –

either the basic rehabilitation protocols (the control group) or

the daily use of CPM for more than six hours together with

basic rehabilitation protocols (the experimental group). The

basic rehabilitation protocols consisted of assisted and active

flexion and extension of the hip/knee, active isometric

contraction of the quadriceps, straight leg raising training,

walking with a high walker or crutches and eventually

climbing stairs on crutches. Based on Altman’s nomogram

with a standard difference of 0Æ75 (i.e. a clinically relevant

difference of 158 with a standard deviation of 208), a power

of 80% and a significance level of 0Æ05, the sample size was

calculated to reach 55 patients (for two groups) (Altman

1999). A group of more than 30 subjects were chosen.

Patients

All patients with osteoarthritis admitted to Kaohsiung

Medical University Hospital by two experienced surgeons

specialising in adult reconstruction were enroled. Before

L-H Chen et al.


390 Journal of Clinical Nursing, 22, 389–394

operation, all patients could walk with and/or without a

walking aid. The knee on one side was operated on in each

patient because advanced osteoarthritis. Patients with rheu-

matoid arthritis or prosthesis in the ipsilateral hip were

excluded. All patients were available for follow-up.

Procedure

The choice of epidural anaesthesia or general anaesthesia was

made by the anaesthetist. The prosthesis used in all patients

was a fixed-bearing posterior-stabilised high-flex knee (Leg-

acy High Flex; Zimmer, Warsaw, IN, USA). The patella was

resurfaced in every patient. All the components were fixed

with cement.

The same postoperative rehabilitation protocol guidelines

were used for all patients, except the addition of CPM. The

exercises were performed for 30 minutes daily, starting on

the first day after surgery and were adjusted to the patient’s

degree of pain. For the CPM, the patient lay in a supine

position in the CPM machine. On the first day after

operation, the machine was set to at least 70� as tolerated

and to as much as 100� for flexion, and the knee was moved

continuously for at least two hours each in the morning,

afternoon and evening. The next day the machine was set at

100� flexion. Between sessions, the knee was placed in the

extended position. All patients were discharged at the fourth

day after operation and followed the exercise protocol given

by the hospital after discharge. Outpatient treatment was not

standardised.

Measures and follow-up

Knee ROM, in terms of active and passive flexion and

extension, was measured by a goniometer with the patient in

a supine position. Knee flexion was measured with the hip at

90� flexion. The goniometer swivel centre was placed on the

lateral side of the knee centre, with one arm aligned with the

greater trochanter and the other along the line running from

the fibular head to the lateral malleolus of the ankle (Norkin

& White 1995). The knee was moved to maximum flexion

and the range measured in degrees.

Pain intensity in the knee was measured by means of a

100 mm visual analogue scale (VAS), where 0 indicated no

pain and 100 indicated unbearable pain (Boeckstyns & Backer

1989). During hospitalisation, VAS was recorded every day.

The quality of life of the patients was evaluated with the

modified Short Form-36 (SF-36) (IQOLA SF-36 Taiwan

Standard Version 1.0, Taoyuan, Taiwan) questionnaire. The

SF-36 contains 11 dimensions, including: (1) Self-evaluation of

general health condition, (2) Comparing the current health

condition with the condition one year ago, (3) The restriction

of daily activity including vigorous exercise, moderate exer-

cise, stair climbing and walking distance by health condition,

(4) The restriction of work by health condition, (5) The effect

of emotion on work, (6) The impairment of daily activity with

family, neighbours and community because of health condi-

tion and emotion, (7) The extent of pain during the past

month, (8) The effect of pain on daily activity and work during

the past month, (9) The feeling during the past month, (10) The

effect of health and emotional problems on social activity, and

(11) The concept of self-health. The scores ranged from 1–5 on

each item, with the lowest score indicating the best condition,

and the highest, the worst condition. The SF-36 result was

calculated by taking the mean of all 11 items. The ROM and

semi-quantitative VAS were recorded by a well-trained study

nurse. All the parameters were evaluated at the time of

admission and followed up by the same study nurse. The

patients were scheduled to return for evaluation at two, six

weeks, three and six months postoperation. The ROM, VAS

and Short Form-36 were evaluated at every visit by the same

study nurse.

Statistical analysis

All data were presented as mean ± standard deviation (SD).

The Mann–Whitney test was used to analyse the efficacy

between study groups. Repeated analysis of variance (ANOVAANOVA)

was implemented to examine the differences at various time

points. All tests were two-sided and performed at the 5%

level and analysed with SPSSSPSS statistical software (version 14.0;

SPSS Inc., Chicago, IL, USA).

Results

Baseline characteristics

Between January 2007 and June 2007, 107 patients who had

undergone TKA were assigned to one of two groups, the

control and the experimental group. The detailed preopera-

Table 1 Demography and symptom duration of the patients

Treatment group Control group p-value

Number of patients 68 39

Age (year) 69Æ25 ± 6Æ79 69Æ46 ± 8Æ17 0Æ89

Body weight (kg) 64Æ48 ± 10Æ83 65Æ41 ± 10Æ35 0Æ67

Preoperative ROM

(degree)

92Æ69 ± 14Æ14 95Æ13 ± 9Æ35 0Æ76

Symptom duration

(months)

82Æ16 ± 70Æ47 68Æ15 ± 51Æ07 0Æ28

Clinical issues Aggressive CPM does not improve ROM after TKA


Journal of Clinical Nursing, 22, 389–394 391

tive comparison of the two groups is shown in Table 1. There

was no difference between these two groups in terms of

demography and the duration of painful osteoarthritis

symptoms (Table 1).

Range of motion

During hospitalisation, the patients in the treatment group

used CPM significantly longer (16Æ90 ± 6Æ95 hours) than

those in the control group (0). Although the patients in the

treatment group used CPM more than six hours daily, they

did not have greater ROM and pain during hospitalisation.

ROM was nearly the same in the treatment group

(92Æ69 ± 14Æ14) as in the control group (95Æ13 ± 9Æ35).

ROM increased from 109� preoperatively to 125� at six

months after operation in the treatment group and from 111�preoperatively to 125� at six months after operation in the

control group. There was no significant difference in ROM

between groups at each visit (Table 2). No patients received

manipulation under anaesthesia because poor ROM. The

results disproved our hypothesis.

Pain

The VAS of the patients in the treatment group (6Æ44 ± 1Æ74)

and the control group (6Æ26 ± 1Æ92) did not differ signifi-

cantly. VAS decreased from 7Æ78 preoperatively to 0Æ37 at six

months after operation in the treatment group and from 7Æ92

preoperatively to 0Æ21 at six months after operation in the

control group. There was no significant difference in VAS

between groups at each visit (Table 2). The results disproved

our hypothesis.

Quality of life

The SF-36 improved from 3Æ76 preoperatively to 1Æ77 at six

months postoperatively in the treatment group and decreased

from 3Æ68 preoperatively to 1Æ83 at six months postopera-

tively in the control group. There was no significant differ-

ence in SF-36 between groups at each visit (Table 2). The

results disproved our hypothesis.

Discussion

In our study, we found that compared with active exercises

alone, CPM had no additional effect on knee ROM, pain or

quality of life postoperatively up to six months after TKA.

Two weeks after TKA, both groups had a statistically

significant reduction in pain intensity compared with base-

line. Six weeks after TKA, both groups had the same knee

ROM compared with baseline and less pain than before. Pain

decreased and ROM increased with time, from two weeks to

six months postoperatively. At the end of follow-up, nearly

all patients had an average of 125� ROM and less than one in

the VAS. In every measurable parameter, there was no

significant difference between groups.

A meta-analysis showed improved flexion at two weeks

postoperatively, a decreased length of hospital stay and a

decreased incidence of manipulation under anaesthetic with

CPM use (Milne et al. 2003). Our results are compatible with

those of previous studies by Beaupre et al. (2001), Leach

et al. (2006), Chen et al. (2000) and Milne et al. (2003). In

both groups, ROM at three months after TKA was better

than the preoperative ROM. This improvement may be due

to the healing of the structures surrounding the joint (Bruun-

Olsen et al. 2009). In some studies, ROM at three months

Table 2 The results of the preoperative and postoperative ROM, VAS and SF-36

Preoperative Two weeks after TKA Six weeks after TKA Three months after TKA Six months after TKA

ROM

Treatment group 92Æ69 ± 14Æ14 102Æ33 ± 9Æ17 110Æ51 ± 9Æ74 119Æ26 ± 8Æ86 125Æ51 ± 5Æ99

Control group 95Æ13 ± 9Æ35 105Æ00 ± 10Æ76 113Æ21 ± 10Æ03 119Æ10 ± 9Æ31 125Æ13 ± 6Æ44

p-value 0Æ76 0Æ78 0Æ86 0Æ88 0Æ81

VAS



p-value 0Æ78 0Æ62 0Æ81 0Æ57 0Æ37

SF-36



p-value 0Æ67 0Æ72 0Æ81 0Æ74 0Æ87

ROM, range of motion; VAS, visual analogue scale.

L-H Chen et al.



after TKA did not reach the preoperative level (Bruun-Olsen

et al. 2009). But another study showed that at six weeks after

TKA, ROM had returned to the preoperative level, similar to

our result (Leach et al. 2006). No patient with poor ROM

required manipulation of the knee joint in our study, even in

the control group.

The difference between preoperative ROM and ROM at

six months after TKA was even greater. Our patients did not

receive special rehabilitation at local hospitals or rehabilita-

tion clinics after discharge, which meant that if the patients

could maintain the rehabilitation protocols learned in the

hospital, ROM could increase with time, even though we do

not know how conscientious they were about practicing the

exercises.

There are some limitations to this study. First, this was not

a randomised controlled study. Second, the rehabilitation

protocol after discharge was not standardised. Third, the

number of patients was not so large, which sometimes may

result in less ability to tell the difference between groups.

However; according to the sample size calculation, our

sample size was adequate to make this distinction.

Conclusion

In conclusion, with the advances in TKA surgical techniques,

aggressive CPM does not provide obvious benefits in ROM

and quality of life. However, aggressive CPM does not induce

more pain.

Relevance to clinical practice

Alleviating pain and improving ROM are the central com-

ponents of nursing in the postoperative care of patients

receiving TKA. It is important to monitor the effects of

aggressive CPM on pain and ROM. The results of this study

indicate that patients undergoing TKA can have less pain and

better ROM and life quality six months after operation, but

aggressive CPM during hospitalisation does not provide

additional benefits. Therefore, we do not suggest routine use

of aggressive CPM after TKA.

Acknowledgements

This research was supported by and National Health

Research Institute of Taiwan (NHRI-EX99-9935EI) and

Kaohsiung Medical University Hospital (KMUH95-5N52

and KMUH96-6R08).

Contributions

Study design: H-TH, L-HC, JYS, Y-MC; data collection and

analysis: S-YL, S-HC, C-YH, H-YW, C-LC, T-YT and

manuscript preparation: L-HC, C-HC, H-TH.

Conflicts of interest

The authors declare that they have no conflict of interests.

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