Retrospective Cohort Study of 207 Cases of Osteochondritis Dissecans of the Knee: Risk Factors and Outcomes Associated with Surgical Treatment

OBJECTIVES: Describe the clinical characteristics, image findings, and outcomes of patients with juvenile osteochondritis dissecans (JOCD) of the knee. To our knowledge, this is the largest single-surgeon cohort of JOCD patients. METHODS: Retrospective cohort study of knee JOCD patients assessed by a single pediatric orthopaedic surgeon at a tertiary care center between 2005-2015. All diagnoses were confirmed by magnetic resonance imaging (MRI). Patients with patellar dislocations or osteochondral fractures were excluded. Demographic data, sports played, comorbidities, surgical procedures, and clinical data were extracted from charts. Images were analyzed to identify the location and size of lesions. Chi-square or Fisher’s exact tests were used to compare discrete variables, and Mann-Whitney U and Kruskal Wallis tests to compare continuous variables between groups. P-values of <0.05 were considered significant. RESULTS: Sample consisted of 180 patients (207 knees), 124 boys and 56 girls. Average age at diagnosis was 12.8 years (7.5-17.5). Majority were active in sports (80.8%), primary soccer (36.7%) and basketball (29.4%). JOCD was present bilaterally in 27 patients (15%), 14 knees had bifocal OCD (6.8%), and only 1 patient had bifocal lesions in both knees. Most common location was medial femoral condyle (56.3%) followed by lateral femoral condyle (23.1%), trochlea (11.4%), patella (9%), and tibia (0.5%). In the sagittal view, most common location was the middle third of the condyles (48.7%). Surgery was performed in 72 knees (34.8%), with an average age at surgery of 14.1 years (9.3-18.1). Bilateral JOCD was present in 13 surgical patients (18.8%), but only 3 patients had bilateral surgery. Two operative patients had bifocal JOCD (2.7%) and surgery on both lesions. Location distribution did not differ between surgical and non-surgical lesions. The average normalized area of non-surgical JOCD lesions was 6.8 (0.1-18), whereas surgical lesions averaged a significantly higher area of 7.7 (0.5-17) (p=0.023). Average BMI was 21.6 versus 20.2 for surgical and non-surgical patients, respectively, significantly higher for those who underwent surgery (p=0.002). Most common procedure was fixation with 1.6 mm bioabsorbable nails (54.2%), using an average of 4 nails (1-9). Only 2 cases were fixed using metallic headless screws. Other surgical treatments were drilling (13.9%), microfracture (13.9%), microfracture + fixation (6.9%), removal of loose body/chondroplasty (6.9%), and allograft transplantation (4.2%). Fixation was achieved all-arthroscopic in 43.1% of the cases, and 61.3% of the lesions that were fixed underwent curettage of the subchondral bone. Revision surgery was required in 14 knees (19.4%). The most common revision procedures were microfracture, removal of hardware, chondroplasty and allograft implantation, where some revisions had combined procedures. Most surgical patients had postoperative MRIs (55 knees), with an average radiological follow-up of 14.5 months (range 2.1-55.4). CONCLUSION: JOCD occurs more frequently in young adolescent athlete boys, affecting the middle third of the medial femoral condyle. In our cohort, 1/3 of the patients had surgery, where bigger lesions and higher BMI were risk factors for operative treatment. At short-term follow up, the success rate following surgery was above 80%.