Study design: Case series.
Case description: Four patients who had developed knee extension motion loss following anterior cruciate ligament reconstruction were referred to physical therapy for treatment. They were treated with drop-out casting and completed a Lower Extremity Functional Scale at baseline, at the time of application of the drop-out casting, and at discharge.
Outcomes: Three males and 1 female with a mean age of 20.5 years (range, 18-22 years) were referred to physical therapy a mean of 31 days (range, 19-49 days) following bone-patella tendon-bone autograft anterior cruciate ligament reconstruction. The mean number of physical therapy sessions attended was 29.5 visits (range, 20-47 visits). The mean improvement in knee extension range of motion (ROM) and knee flexion ROM prior to the application of drop-out casting was 4.3 degrees (range, -1 degree to 10 degrees) and 24.3 degrees (range, 0 degree to 40 degrees), respectively. The mean improvement on the Lower Extremity Functional Scale was 10.3 points prior to drop-out casting. At time of discharge, the total mean improvement in knee extension ROM loss was 11.0 degrees (range, 4 degrees to 15 degrees), knee flexion ROM was 30.8 degrees (range, 22 degrees to 35 degrees), and Lower Extremity Functional Scale was 12 points (range, -5 to 21 points). Two of the patients were able to complete a running program without difficulty, while the other 2 patients had difficulty with higher-level activities.
Discussion: Despite the low incidence of knee extension ROM loss following surgery, the inability to achieve full knee extension does occur and can have debilitating consequences. When early emphasis of full passive knee extension has been inadequate, these results suggest that improving knee extension motion without inhibiting knee flexion motion is possible with the use of a drop-out cast. Future research should focus on comparison of drop-out casting to dynamic splinting, as well as the optimal frequency and duration of low-load long-duration stretching using a drop-out cast.