The combination of MPFL reconstruction and TTO in patients with trochlear dysplasia results in low recurrence of instability with most athletes able to return to sport with good subjective outcomes.
Lateral patellar instability is a debilitating condition with numerous etiologies and possible treatment options. Medial patellofemoral ligament (MPFL) reconstruction and tibial tubercle osteotomy (TTO) are each accepted management strategies, but few have reported on the use of both techniques in select patients with multiple anatomic risk factors for instability.
The medical record at our institution was reviewed for patients treated with MPFL reconstruction and TTO for chronic lateral patellar instability from 1998-2014. All patients with a minimum two year follow up were included. Preoperative imaging was assessed for trochlear dysplasia according to the Dejour classification (high grade = B, C, and D) and the presence of patella alta using the Caton-Deschamps ratio (CDR>1.2). The indication for combined MPFL reconstruction and TTO was MPFL insufficiency and a lateralized tibial tubercle. Outcomes were obtained via recurrent instability, return to sport, and Kujala and IKDC scores.
Thirty knees in 28 patients (14 M, 14 F) with a mean age 22.6 years (range 13-51) were included with a mean follow up of 48 months (range 24-123). Seventy three percent (22/30) of knees had high grade trochlear dysplasia, and 63% (19/30) had patella alta. One patient had a repeat dislocation, and one patient experienced postoperative subluxation. In the absence of formal distalization, the CDR decreased by a mean of 0.2 p=0.001), leaving only 30% with patella alta.The mean postoperative Tegner score was 5.The mean scores for Kujala and IKDC were 89 (45-100) and 85 (44-100) respectively. Eighty three percent (15/18) returned to their preoperative sport. BMI, age, cartilage status, trochlear dysplasia, and the presence of patella alta had no significant effect on final scores. Female gender was a risk factor for lower IKDC (77.3 vs 92.6, p=0.01) and Kujala (82.2 vs 95.0, p=0.03) scores. The mean TT-TG from axial MRI or CT was 19.6 ± 3.2 preoperatively, and the mean distance of TT medialization measured intraoperatively was 9.2. Increased amount of TT medialization, independent of initial TT-TG, was directly correlated to lower IKDC (p=0.02) and Kujala (p=0.03) scores as well as lower postoperative Tegner scores (p=0.0002).
The combination of MPFL reconstruction and TTO in patients with trochlear dysplasia results in low recurrence of instability. Most athletes were able to return to sport , and patients on average had good subjective outcomes. Female gender and an increased distance of TT medialization, independent of initial TT-TG, were risk factors for worse outcomes.