OBJECTIVES

Osteochondritis dissecans (OCD) lesions of the talus often occur in young athletes following ankle trauma, with an estimated 6.5% distortions resulting in talar dome OCD lesions. Lesions are commonly found centrolaterally (20-25%) and posteromedially (26-30%). Advanced OCD lesions may require treatment with an osteochondral graft. Minimizing graft step-off is crucial to prevent contact load mismatch and early failure of the repair. This study sought to characterize the talar dome sagittal radius of curvature (ROC) of two common locations of post-traumatic talar OCD lesions.

Methods

Ankle Magnetic Resonance Imaging studies from 30 patients (age 9-17) were analyzed using Sectra imaging software (Linköping, Sweden). Three reviewers independently measured Talar ROCs in the sagittal plane at both centrolateral and posteromedial locations. Axes in each study were reoriented using the 3D function of Sectra to achieve measurements orthogonal to the talar dome surface. Paired two-tailed t-tests were performed for statistical analysis. Inter- and Intraobserver agreement was examined using the “IRR” Intraclass Correlation Coefficient R package. Fisher’s test was utilized to combine and review p-values from the individual observer’s paired t-tests.

Results

All interobserver reliability coefficients were greater than 0.8 and 0.6 for the posteromedial and centrolateral locations respectively. All intraobserver reliability coefficients were greater than 0.8 and 0.6 for the posteromedial and centrolateral locations respectively. Mean ROC measurements significantly differed, with 20.6mm and 17.2mm at the posteromedial and centromedial locations respectively.

Conclusion

ROC at the centrolateral and posteromedial locations of the talar dome differ significantly, with the latter being larger by 15%. Our data suggests this difference may need to be taken into consideration when selecting potential osteochondral graft harvesting locations for reconstruction of full-thickness defects. This may optimize repair and support better acute and long-term outcomes.