ABSTRACT
BACKGROUND: Patellofemoral instability is a complex problem with most previous treatment plans addressing static alignment and static stabilizers. Although the quadriceps muscles are known to affect the tracking of the patella, they are rarely taken into account during a surgical procedure. PURPOSE: The purpose of this study is to determine the two year minimum results of 37 knees which received a Southwick-Fulkerson Osteotomy and MPFL repair or reconstruction both under the guidance of femoral nerve stimulation. METHODS: Patients underwent a Southwick-Fulkerson Osteotomy and either medial patellofemoral ligament (MPFL) repair or reconstruction using femoral nerve stimulation as a means of dynamic intraoperative evaluation of patello-femoral congruity in terminal extension. Two year minimum outcomes of 26 patients, 31 knees (84% return rate) were evaluated using KOOS and IKDC scores, and physical exam features of apprehension and assessment of dynamic tracking in the last 30 degrees of knee extension. Variables were evaluated with t-tests and ANOVA. RESULTS: 29/31 knees reported they were happy with the procedure and reported they would do it again. One knee (3%) reportedly "redislocated", but did not return for verification by exam. 30/31 had non-pathologic tracking. One knee displayed a small but residual J sign. 4/16 knees with MPFL repair only and 0/15 with MPFL repair and reconstruction exhibited a positive apprehension sign. Increased age and apprehension were correlated with lower outcome scores. CONCLUSIONS: Intraoperative femoral nerve stimulation is an effective way of evaluating patellar tracking intraoperatively that leads to 97% stable patellae with near congruent patello-femoral tracking. MPFL reconstruction is superior to MPFL repair in eliminating the persistence of the apprehension sign.
