RADIOLOGIC EVALUATION OF TALAR DOME CONFIGURATION

Abstract

Introduction: Osteochondral lesions (OCL) of the talus are a common pathology among patient who suffered a traumatic injury of the ankle joint and involve breakdown of articular cartilage and underlying bone tissue. The estimated incidence of OCL is 6% in all ankle sprains and the importance of a traumatic ankle event was confirmed by several authors by arthroscopical joint assessment. The most common locations for OCL to occur are at the posteromedial and anterolateral aspect/section, involving the mortise/edge of the dome. One of the orthopaedic world’s most current research topics is the aim to produce tissue engineered osteochondral grafts for future treatment of OCL lesions. For the exact anatomic reconstruction, the dimensions of the medial and lateral talar dome must be considered. Few data is available regarding the normal anatomic talar dimensions on standard radiographs of ankle joints. The purpose of this study was to collect data describing the normal talar dome anatomy of the ankle joint on antero-posterior hindfoot radiographs and to assess value distribution in a large patient group. Hypothetically the medial talar dome has a significant greater curvature and a greater edge angle than the lateral talar dome.

Methods: 81 patients (81 ankles) (30 female, 51 male; average age 43y (range 20–87y)) without ankle and hindfoot pathologies were included. Weight-bearing standard AP ankle radiographs were performed on a digital flat panel system (Aristos FX^®, Siemens Erlangen, Germany) and evaluated on a high resolution case reading monitor (Totoku) using DICOM/PACS review application E-Film.

1. To measure the edge angle of the medial (α) and lateral (β) talar dome, curves were adjusted along the medial and lateral talar body and on top of the talar dome measuring the angles in-between.

2. To measure the radius, circles were fitted into the medial and lateral talar dome (rm and rl).

Results: There was a significant difference (p< 00.1) between mean medial edge angle (α) with 109.99 degree (range 90–127; SD 7.14) and lateral edge angle (β) with 91.84 degree (range 79–111; SD 5.56). Also a significant difference (p< 00.1) has been demonstrated between the mean medial talar dome radius (rm) with 4.8 mm (range 2–8; SD 1.3) and lateral talar dome radius (rl) with 3.5 mm (range 1.2–8.5; SD 1.5).

Conclusion: This study shows a significant difference between medial and talar dome configuration. The assessed data provides important aid for engineering of pre-formed, pre-sized osteochondral grafts. Such pre-shaped grafts could help restoring the physiological joint surface by matching exactly into the lesion and consequently achieving the recovery of the physiological joint biomechanics and prevention of secondary degenerative disease.