Extra-articular Drilling for Adolescents with Osteochondritis Dissecans of the Talus: A Lost Cause or a Call to Develop Better Treatment?

OBJECTIVES: To determine the radiographic outcome and need for further surgery in children with osteochondritis dissecans (OCD) of the talus treated with extra-articular drilling. Children requiring further surgery for pre-operative risk factors of the initial failure were also evaluated. METHODS: Fifty-six ankles were identified between August 2006 and August 2012 with talus OCD that underwent extra-articular talar drilling. Demographic data, mechanism of injury, conservative treatment history, surgical details of initial treatment and subsequent treatment, if necessary, was collected. Pre-operatively, radiographs were evaluated for physeal status, signs of osteoarthritis according the Kellgren and Lawrence Scale, location of the lesion, border, and size of the lesion. Each lesion was classified according to the Berndt and Harty classification for radiographs, Hepple classification for MRI, and Ferkel and Sgaglione for CT. Radiographs at each follow-up visit were evaluated by a Healing matrix that assessed serial changes in lesion length, lesion depth, perilesional sclerosis, or density of the lesion. At final follow-up, lesion size, border, Berndt and Harty classification, and signs of osteoarthritis were recorded. RESULTS: At final follow-up, all but one lesion showed radiographic improvement but no lesion reached complete radiographic resolution. The mean Healing matrix score at final follow-up was 59/100. Risk factors for reaching statistical significance for poor healing included closed physes (p = 0.025) and lesions with a distinct border (p = 0.029). Age, size of lesion, and length of follow-up did not correlate with healing. Comparison of pre-operative and final follow-up radiographs showed no significant change in the size or border of the lesion. For the 23% of children who underwent a second surgery, they were found to have a lower Healing matrix score after index surgery compared to those without repeat surgery, p < 0.001). Moreover, patients with closed physes were more likely to have second surgery, 38% vs. 14% (OR 3.7). After a second extra-articular talar drilling surgery, the mean Healing matrix score improved to match the mean of the entire cohort. CONCLUSION: Extra-articular talar drilling of OCD does not appear to improve radiographic outcomes as compared with other reported techniques of intra-articular drilling. As with other joints, successful radiographic resolution is associated with open physes - highlighting that children have better OCD healing potential. Other modalities of talus OCD treatment should be explored, especially for higher-grade lesions at risk for instability, since the radiographic results of current drilling techniques are disappointing.