Paper 27: Suture bridge fixation for medial femoral condyle osteochondritis dissecans demonstrates comparable healing compared to screw fixation

Objectives: The purpose of this study was to compare the clinical and imaging-based healing outcomes of unstable medial femoral condyle (MFC) osteochondritis dissecans (OCD) lesions treated with either headless screw fixation or suture bridge (SB) fixation.
Methods: Unstable MFC OCD lesions treated with fixation between 2017-2024 at a single academic sports medicine institution were included in this retrospective, IRB-approved, cohort study. Lesions were fixed using either metallic headless compression screws or a suture bridge technique with bioabsorbable knotless anchors with multiple strands of absorbable or nonabsorbable bridging suture. Demographic characteristics, pre-operative imaging findings, surgical details, healing on final magnetic resonance imaging (MRI), ICRS partial thickness or greater secondary wear changes on the adjacent articular surface (in cases of subsequent operation), and conversion to osteochondral allograft (OCA) were analyzed. Clinical outcomes were based on failures defined as conversion to osteochondral allograft or repeat surgery. Imaging outcomes were based on healing noted on advanced imaging (MRI). Categorical variables were compared using chi-square or Fisher's exact test, and continuous variables were compared using a two-tailed t-test or a Mann Whitney U test depending upon the assessed normality of the samples.
Results: A total of 75 MFC OCD lesions were included (34 screws, 41 SB) with an average follow up of 19.8 months (range, 4-61 months). Groups were not statistically different in age, sex, BMI, ethnicity, and follow up duration. However, lesions treated with SB were significantly larger in surface area (4.4 +- 1.9 vs. 3.3 +- 1.5 cm², p=0.032) and deeper (10.1 +- 1.5 vs. 8.8 +- 2.0 mm, p=0.0015).Lesions treated with SB were more likely to undergo drilling with debridement and local autologous bone grafting (73.2% vs. 35.3%, p=0.0004) while lesions treated with screw fixation more frequently underwent adjunctive application of bone marrow aspirate concentrate (BMAC) (70.6% vs. 22.0%, p<0.0001). Implant removal rate was similar between the two groups, however SB had a longer time to suture removal (8.5 +- 7.8 vs. 4.9 +- 3.8 months, p=0.0076). Importantly, all instances of suture bridge removal were planned at the time of the index procedure; however, this was not the case in the screws group. In cases of subsequent surgical intervention for implant removal or OCA, secondary wear of the adjacent tibial articular surface was noted with 3 cases (9.1%) in the screw group resulting in ICRS grade IV secondary lesions, and 1 (3.7%) grade II lesion in the SB cohort (p<0.0001).Conversion to OCA occurred at a similar rate and time point between groups, with 14.7% in the screw group and 19.5% in the SB group (p=0.5841), at an average of 12.7 +- 8.7 vs. 12.6 +- 9.2 months, respectively (p=0.8329). OCD healing on final MRI (excluding lesions converted to OCA) was also similar: fully healed in 51.7% screws vs. 57.6% SB, >=50% healing in 44.8% screws vs. 39.4% SB (p=0.8961). Among lesions that did not require conversion to OCA, only one case in each group showed < 50% healing.
Conclusions: In this retrospective cohort study, despite significantly larger and deeper lesions in the suture bridge group, outcomes with respect to healing on MRI and conversion to OCA were not significantly different compared to metallic headless compression screw fixation. Additionally, the screw cohort was associated with an 9.1% rate of ICRS grade IV secondary articular surface lesions with no high-grade lesions noted in the SB cohort. This suggests that a suture bridge construct is a reliable alternative to screw fixation with less potential for severe secondary adjacent articular damage in the management of complex MFC OCD lesions.