Proponents of quadriceps-sparing (QS) subvastus approach for total knee arthroplasty (TKA) suggest short-term advantages including better early functional results, less pain and shorter hospital stay. However, because of potentially reduced visibility and exposure, the QS approach may compromise component alignment – an important surgeon-controlled outcome affecting implant longevity. The purpose of this study was to determine if a QS approach resulted in compromised component alignment compared to a medial parapatellar arthrotomy (MPPA), when both were performed with contemporary minimally invasive surgery (MIS) principles including small incision (≤ 15 cm), MIS instrumentation, patellar subluxation without eversion, and in situ bone cuts. This prospective, randomized, double-blinded study enrolled 128 patients with knee osteoarthritis undergoing primary TKA using the same cemented, posterior-stabilized prosthesis. After skin incision, patients were randomized to MPPA (n = 66) or QS technique (n = 62), with all surgeries performed by two fellowship-trained arthroplasty surgeons. Using the Knee Society roentgenographic evaluation system, two reviewers blinded to the surgical approach evaluated post-operative radiographs to measure coronal and sagittal plane alignment using the standing femoral and tibial angles as well as the lateral femoral flexion and tibial angles. Inter-observer agreement was ensured by a secondary review of all x-rays where the two observers differed by more than 1 degree in their measurements of a specific radiograph. Differences in mean angles were evaluated using the general linear model and differences in proportions were evaluated using binary regression. All analyses were conducted with SAS 9.3 on the Windows Ultimate 64-bit operating system.Introduction:
Methods:
Clinical trials have generally failed to demonstrate superior clinical effectiveness of minimally invasive surgical approaches for total knee arthroplasty (TKA). The hypothesis of the current study was that avoiding incision of the quadriceps tendon would result in a significantly faster recovery of ambulatory function after total knee arthroplasty, compared to a technique that incised the quadriceps tendon. The MIKRO (Minimally Invasive Knee Replacement Outcomes) Study is a prospective, level 1 RCT that enrolled 128 patients with knee osteoarthritis who had failed non-operative treatment, and had decided to proceed with TKA. After skin incision, 64 patients each were randomized to either a subvastus (SV) or medial parapatellar arthrotomy (MPPA) approach. All surgeries were done with the same TKA implant, with anesthesia, post-operative analgesia, and physical therapy standardized for both groups. A Patient Diary methodology was used as the primary outcome measure for ambulatory function. During the first 8 weeks after TKA, a research assistant blinded to treatment assignment telephoned each patient and completed study forms that documented indoor and outdoor walking relative to use of ambulatory devices, as well as Knee Society Score (KSS) and the UCLA activity scale. The UCLA score and change in KSS from baseline at 4- and 12-week follow-up were used to begin the validation process for an Ambulatory Function Score (AFS) derived from diary indoor and outdoor scores.INTRODUCTION
METHODOLOGY
