Accuracy of Schottle's point location by palpation and its role in clinical outcome after medial patellofemoral ligament reconstruction

Abstract

IntroductionMedial patellofemoral ligament (MPFL) reconstruction is performed for the recurrent patellar dislocation (RPD). The crux of sound clinical results depends upon accurate placement of the graft at or within the 7-mm circle of Schottle point (acceptable position) over the femur. Most studies recommend the location of Schottle's point using intraoperative fluoroscopy or seldom by clinical palpation. We conducted a clinical study to understand the accuracy of locating Schottle's point by clinical palpation and its effect on outcome after MPFL reconstruction. Method30 patients with RPD were included in this retrospective study after MPFL reconstruction. Post-operative CTscan was performed to locate the position of the femoral tunnel using Servien grid criteria and Schottle's point location. The clinical outcome was assessed using Lysholm and Kujala Scores at the end of a minimum of two years. Results30 patients (11 male, 19 female) with a mean age of 24.8 years (range, 16–45 years) were followed for a mean of 42 months (range, 24–96 months). Mean Kujala score improved from 53.8 to 91.5 (p = 0.0001), and Lysholm score improved from 59.0 to 93.3 (p = 0.0001) in all 30 patients. Post-operative CT assessment revealed 19 patients (63.3%) had a tunnel in an acceptable position and 11 patients (36.7%) in an unacceptable position. Eight of the eleven unacceptable tunnels were placed in the anteroposterior direction, and three in superior-inferior direction. However, there was no significant difference between the Lysholm and Kujala scores of patients with acceptable versus unacceptable tunnels. ConclusionPlacement of the femoral tunnel over the medial femoral condyle by the palpatory method is accurate in close to 2/3rd of the cases only whereas rest 1/3rd may fall outside the acceptable position. Hence, it is recommended to confirm the placement of femoral tunnel with intraoperative fluoroscopy at the acceptable position to avoid error. Level of studyRetrospective case series, level IV.