Use of drop and dangle rehabilitation protocol to increase knee flexion following total knee arthroplasty: a comparison with continuous passive motion machine

There are variations in the type of rehabilitation program and duration of using the continuous passive motion (CPM) machine to increase range of motion (ROM) following total knee arthroplasty (TKA). To compare the outcomes of the 'drop and dangle' (D&D) protocol vs. a 3-hour daily CPM for the purpose of increasing flexion following TKA. A prospective non-concurrent controlled intervention study was conducted on patients who underwent primary TKA atLampang Hospital from December 2009 to August 2011 (D&D group, n = 36) andfrom September 2011 to December 2012 (CPM group, n = 33). The same surgeon using the same prosthesis design performed all surgeries. The legs in D&D group were placed into the knee immobilizer at 70 flexion and removed on postoperative day 1 (POD1). The passive ROM exercise was then started by dropping the affected leg over the bedside, and gently flexing and bending the knee with the help of the unaffected leg to achieve maximal flexion. The legs in the CPM group were immobilized with a Jones bandage in full extension for 24 hours, and then placed into CPM machine for three, 1-hour per day sessions. The clinical data were statistically compared between the two groups. Patient baseline characteristics in both groups were not different. The D&D group had more average passive flexion in POD1 (67.0° ± 14.2° vs. 59.1° ± 3.2°, p < 0.001) and POD2 (76.6° ± 14.2° vs. 69.8° ± 13.3° , p = 0.008). Higher rates of flexion were observed in PODs 3-7 but they were not significant. Flexion at discharge in the D&D group was 100.6° ± 6.8° and 96.4°+10.2° in the CPM group (p = 0.005). At 6 weeks, rates of flexion in both groups were similar (D&D 99.8° ±10.4°, CPM 103.9° ± 10.4°, p = 0.138). Rates offlexion were also similar at 1 year (D&D 112.0° ± 10.4°, CPM 111.6° ± 12.6°, p = 0.892). D&D protocol provided more passive knee flexion than the use of CPM in the first two days after TKA and at discharge. These differences were not significant at 6 weeks and 1 year