Clinical Comparative Study between Modified Drop and Dangle Exercise and Continuous Passive Motion Machine to Increase Flexion after Total Knee Replacement

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ดวงรักษ์ สวัสดิ์ภาพ
อนุวัตร พงษ์คุณากร


Background: Postoperative total knee replacement (TKR) exercise with early passive flexion, namely ‘drop and dangle protocol’, had been proposed to increase range of motion (ROM) as effective as with using a continuous passive motion machine (CPM). This technique was modified and implemented in Lampang Hospital.
Objective: To compare outcome of modified ‘drop and dangle’ exercise and 3-hours daily CPM for increasing knee flexion following primary TKR.
Material and method: A historical controlled-trial was conducted on the patients who underwent  unilateral TKA in Lampang Hospital from December 2007 to November 2009 (control group, n=41) and from December 2009 to December 2011 (study group, n=41) by the same surgeon and prosthesis design. Postoperatively the leg in study group was placed into the knee immobilizer in 70° flexion and removed in postoperative day 1. ROM exercise was started by bedside dropping the leg, dangling and passively bending the knee to achieve maximal flexion by the help of opposite foot. The leg in control group was splinted with Jones bandage in full extension, then placed onto CPM machine in the next day. Both groups consumed three 1-hour sessions per day. Pre-and-postoperative clinical data were prospectively collected in study group and retrospectively reviewed in control group. The outcomes were compared by using exact probability test and Wilcoxon’s rank-sum test.
Results: Preoperatively, patients’ characteristics were similar in both groups. Postoperatively, the study group had less time to achieve 90° of flexion (3.1 vs 3.5 days, p=0.237) and higher passive flexion at discharge but not statistically significant (100.9° vs 97.6°, p=0.078). At 6-week followup, no significant difference of knee flexion was detected between the control and study group (104.2° vs 101.3°, p=0.161), including at 1-year (110.6° vs 112.3°, p=0.814) and 3-year
(112.4° vs 114.0°, p=0.892). ROM achieved from 3-hours daily use of CPM was comparable to those obtained from different daily duration of CPM use in previous studies.
Conclusion: Modified drop and dangle exercise could increase knee flexion after TKR as high as use of CPM during admission, at 6-week, 1-year and 3-year follow-up. For patients exempted to this exercise, only 3-hours daily use of CPM can regain flexion motion comparably to longer daily duration of application.


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สวัสดิ์ภาพ ด., & พงษ์คุณากร อ. (2015). Clinical Comparative Study between Modified Drop and Dangle Exercise and Continuous Passive Motion Machine to Increase Flexion after Total Knee Replacement. Lampang Medical Journal, 36(1), 14–25. Retrieved from
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