Minimally Invasive Knee Arthroplasty with the Subvastus Approach Allows Rapid Rehabilitation: a Prospective, Biomechanical and Observational Study

[Purpose] To study the recovery of patients treated with minimally invasive total knee arthroplasty (TKA) performed via the subvastus approach, and to develop an optimal rehabilitation program for these patients. [Methods] Twenty-two patients (17 females and 5 males; mean age 69.2 years), who received unilateral minimally invasive TKA for osteoarthritis, underwent isometric and isokinetic muscle testing and completed a quality of life questionnaire, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), before and after surgery. Muscle strength and ultrasound tests were repeated 1, 2, 6, and 12 months after surgery. [Results] Strength and range of motion were initially lower in the operated knees but demonstrated no significant difference from the healthy knees after 12 months. Sonographically, joint effusion was greater in the osteoarthritic knees than in the healthy knees at baseline, but no significant difference was observed after 12 months. The mean WOMAC pain, stiffness and function scores all decreased from baseline to 6 months, and then slightly increased at 12 months, but only the function score showed a significant difference compared to baseline. [Conclusions] One year after minimally invasive TKA using a subvastus approach, patients had a good overall prognosis, with prompt functional recovery.