Continuous passive motion and its effects on knee flexion after total knee arthroplasty in patients with knee osteoarthritis.
OBJECTIVE
This study evaluated the effects of continuous passive motion (CPM) on accelerated flexion after total knee arthroplasty (TKA) and whether CPM application measures (i.e. initial angle and daily increment) are associated with functional outcomes.


METHODS
A retrospective investigation was conducted at the rehabilitation centre of a university-based teaching hospital. Patients who received CPM therapy immediately after TKA surgery were categorized into rapid-, normal-, and slow-progress groups according to their response to CPM during their acute inpatient stay. Knee pain, passive knee flexion, and knee function-measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)-were assessed preoperatively at discharge and at 3- and 6-month outpatient follow-up visits.


RESULTS
A total of 354 patients were followed for 6 months after inpatient-stay discharge. The patients in the rapid-progress group (n = 119) exhibited significantly greater knee flexions than those in the slow-progress group did (n = 103) at the 3-month follow-up [mean difference (MD) = 10.3°, 95 % confidence interval (CI) 4.3°-16.3°, p < 0.001] and 6-month follow-up (MD = 10.9°, 95 % CI 6.3°-15.6°, p < 0.001). Significant WOMAC score differences between the rapid- and slow-progress groups were observed at the 3-month follow-up (MD = 7.2, 95 % CI 5.4-9.1, p < 0.001) and 6-month follow-up (MD = 16.1, 95 % CI 13.4-18.7, p < 0.001). CPM initial angles and rapid progress significantly predicted short- and long-term outcomes in knee flexion and WOMAC scores (p < 0.001).


CONCLUSIONS
When CPM is used, early application with initial high flexion and rapid progress benefits knee function up to 6 months after TKA.


METHODS
II.
Department of Physical Medicine and Rehabilitation, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan.|School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.
Chun-De
CD
Liao
Department of Exercise and Health Science, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan.
Yi-Ching
YC
Huang
Department of Physical Medicine and Rehabilitation, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan.
Li-Fong
LF
Lin
Department of Orthopedics, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan.
Yen-Shuo
YS
Chiu
Department of Nursing, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan.
Jui-Chen
JC
Tsai
Department of Physical Medicine and Rehabilitation, Taipei Medical University Hospital, Taipei, Taiwan.|Department of Physical Medicine and Rehabilitation, School of Medicine, College of Medicine, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei, Taiwan.
Chun-Lung
CL
Chen
Department of Physical Medicine and Rehabilitation, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan. peter_liou@s.tmu.edu.tw.|Graduate Institute of Injury Prevention and Control, Taipei Medical University, Taipei, Taiwan. peter_liou@s.tmu.edu.tw.|Department of Physical Medicine and Rehabilitation, School of Medicine, College of Medicine, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei, Taiwan. peter_liou@s.tmu.edu.tw.
Tsan-Hon
TH
Liou
D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D008297:Male; D008875:Middle Aged; D015915:Motion Therapy, Continuous Passive / Q000379:methods*; D020370:Osteoarthritis, Knee / Q000601:surgery*; D016059:Range of Motion, Articular; D020127:Recovery of Function; D012189:Retrospective Studies
Continuous passive motion; Knee arthroplasty; Knee functional outcome; Post-operative rehabilitation