Background: Derotational distal femoral osteotomy (DDFO) has been used to treat patients with recurrent patellar dislocation (RPD) with increased femoral anteversion. However, no study has reported second-look arthroscopic findings in the patellofemoral joint after DDFO.
Purpose: To report clinical and second-look arthroscopic outcomes for DDFO with combined medial patellofemoral ligament reconstruction (MPFL-R) in treating RPD with increased femoral anteversion.
Study design: Case series; Level of evidence, 4.
Methods: From 2015 to 2019, 131 consecutive patients (144 knees) with RPD were treated with combined MPFL-R and DDFO. Patients with a femoral anteversion angle >30° and a minimum 2-year clinical follow-up period were included in the study. Three-dimensional computed tomography was performed to evaluate rotational deformities of the lower leg. Radiographic parameters presenting bony abnormalities associated with RPD were measured. Second-look arthroscopic evaluations were available for 86 knees to assess patellar tracking and chondral lesion changes. Moreover, clinical and radiologic outcomes were assessed pre- and postoperatively at a minimum 2 years.
Results: A total of 102 knees in 92 patients were included in the present study with a mean clinical follow-up of 4.1 years (range, 2.0-5.6 years). Mean ± SD femoral anteversion changed significantly from 34.7°± 7.5° preoperatively to 11.3°± 0.2° postoperatively (P < .001), and mean tibial tubercle-trochlear groove distance decreased significantly from 19.6 ± 3.5 mm preoperatively to 17.4 ± 3.2 mm postoperatively (P < .001). In the majority of knees, at the time of second-look arthroscopic assessment, chondral lesion status remained unchanged at the lateral patellar facet (96%) and trochlear groove (95%); in contrast, chondral damage at the medial patellar facet was aggravated in 9 cases (10%). All functional scores (Tegner, Lysholm, visual analog scale, and Kujala scores) improved significantly at final follow-up. None of the patients experienced redislocation or subluxation after surgery.
Conclusion: Chondral lesions in the patellofemoral joint remained unchanged in the majority of cases in second-look arthroscopy after combined MPFL-R and DDFO. Moreover, high-grade trochlear dysplasia and arthroscopic residual patellar maltracking might be associated with cartilaginous deterioration at the medial patellar facet after surgery.
Keywords: chondral lesion; derotational distal femoral osteotomy; femoral anteversion; second-look arthroscopy.