INCIDENCE OF 2(nd) SURGERY AFTER MPFL RECONSTRUCTION AND SIMULTANEOUS OSTEOCHONDRAL FRACTURE FIXATION IN PEDIATRIC PATIENTS TREATED FOR PATELLAR DISLOCATION

BACKGROUND: Osteochondral fractures occur in 5-15% of cases of acute or recurrent patellar dislocations. In these settings, early surgical intervention with biodegradable fixation nails is recommended to optimize healing. PURPOSE: The purpose of this study was to determine the incidence of recurrent instability and second surgery following osteochondral fracture fixation with concomitant medial patellofemoral ligament (MPFL) reconstruction. METHODS: We conducted a retrospective cohort study of 321 MPFL reconstructions performed by a single surgeon between 2011 and 2019. Thirty-eight knees underwent MPFL reconstruction with osteochondral fixation. Demographic data, surgical details, date of latest radiographic and clinical follow-up, and subsequent surgical procedures were collected. RESULTS: Thirty-seven MPFL reconstructions with osteochondral fracture fixation in 36 patients were performed by a single surgeon from 2011 to 2019 (1 bilateral). The average age at surgery was 14.8 years (range 10.6– 19.6 years). The average length of clinical follow-up was 1.9 years (range .1– 5.5 years). The average number of biodegradable fixation nails used was 4.4 (range: 2-8). Twenty-seven (72.9%) fractures were fixed to the patella and 10 were fixed to the lateral femoral condyle or trochlea There was 1 report of recurrent instability. Ten (27%) patients required a second surgery on the ipsilateral knee, and underwent chondroplasty (n=8), removal of biodegradable fixation nails (n=4), removal of hemi-epiphysiodesis or TTO hardware (n=2), revision MPFL with tibial tubercle osteotomy (n=1), lateral meniscus repair (n=1). The one patient who required revision MPFL reconstruction has juvenile idiopathic arthritis and underwent 3 additional surgeries after the initial MPFL procedure. Eight patients (22%) underwent a second surgery to address cartilage damage or removal of nails. The mean time to second surgery was 40.0 weeks (range:11-82.7). Of the four patients who required removal of nails, the average number of nails initially placed was 7 ± 1.7. This was significantly more than the patients who did not require second surgery related to nail removal (4.1 ± 1.6, p < .05). CONCLUSION: Approximately 78% of patients undergoing MPFL reconstruction and osteochondral fracture fixation with biodegradable nails showed good fracture healing and patellar stability while 22% went on to require a second surgery. The second surgery most commonly involved debridement of an unhealed portion of the cartilage.