The relationship between the lesion-to-ankle articular length ratio and clinical outcomes after bone marrow stimulation for small osteochondral lesions of the talus

Purpose The purpose of this study was to determine the relationship between the defect-to-ankle articular length ratio and clinical outcomes after arthroscopic bone marrow stimulation. Methods Seventeen male and 24 female patients (mean age 36.0 years, height 160.7 cm, weight 62.5 kg, body mass index 24.0) with an osteochondral lesion of the talus were treated with arthroscopic bone marrow stimulation and assessed using the Japanese Society for Surgery of the Foot (JSSF) ankle-hindfoot scale, Berndt and Harty scales and clinical outcome criteria. The lengths of the tibial and talar articular surfaces were defined from the anterior tip to posterior tip of the articular cartilage on sagittal magnetic resonance imaging scans. The size of the defect area was defined and determined for each patient on magnetic resonance images using coronal length, sagittal length, and area. The relationship between clinical outcome and sagittal tibia ratio (sagittal length of defect/length of tibia articular cartilage) and sagittal talus ratio (sagittal length of defect/length of talus articular cartilage) were assessed. Results The mean lesion length was 11 mm (range 6-14 mm), lesion size was 67 mm(2) (range 19-134 mm(2)), sagittal tibia ratio was 0.42 (range 0.21-0.75), and sagittal talus ratio was 0.32 (range 0.16-0.58). The mean JSSF scale improved from 74 (range 18-90) to 89 (range 67-100) postoperatively. Lesion area was not associated with the JSSF scale (r = -0.10, P = 0.52). Talus articular length (r = 0.64, P < 0.0001) and tibia articular length (r = 0.64, P < 0.0001) were correlated with patient height. The sagittal talus ratio and sagittal tibia ratio were not associated with the JSSF scale (r = -0.10, P = 0.55; r = -0.02, P = 0.90). Conclusion Arthroscopic bone marrow stimulation provides good clinical outcomes in small osteochondral lesions of the talus (< 15 mm). For small lesions, the lesion size is not a prognostic factor. Level of evidence: IV Retrospective Case Series.