Guidelines for the Early Restoration of Active Knee Flexion After Total Knee Arthroplasty: Implications for Rehabilitation and Early Intervention

ObjectivesTo investigate the association between active knee flexion at initial (1–2wk) and final (7wk) outpatient visits after total knee arthroplasty (TKA), and to develop a guide for the expected progression of knee flexion in the subacute postoperative phase.DesignProspective case series.SettingRehabilitation clinic.ParticipantsConsecutive sample of patients (N=108) who underwent TKA between December 2007 and August 2012.InterventionTKA followed by a standardized, 5-week outpatient rehabilitation program (2 sessions per week) immediately after hospital discharge.Main Outcome MeasureActive knee flexion was recorded on the patient's first outpatient visit (1–2wk) and then biweekly throughout the patient's 5-week outpatient rehabilitation program.ResultsActive knee flexion at initial (1–2wk) and final (7wk) outpatient visits were significantly correlated (r=.86, P<.001). Mean active knee flexion significantly improved (P<.001) across all patients from 90.4° at initial outpatient visit to 110° at final outpatient visit. At 7 weeks postsurgery, a value of 100° was determined as the cut-off point for an acceptable active knee flexion, which corresponded with 80° of active knee flexion at initial outpatient presentation at 1 to 2 weeks.ConclusionsActive knee flexion at the initial outpatient visit exhibits a strong correlation with knee flexion at 7 weeks after TKA. These knee flexion guidelines may allow for the provision of individualized rehabilitation, allow practitioners to provide patients with realistic goals of progression throughout the subacute phase, and allow the early identification of patients at risk for poor long-term outcomes who may benefit from further intensive care or other early intervention.