Osteochondral Lesions of the Distal Tibial Plafond: Localization and Morphologic Characteristics with an Anatomical Grid

Background: The aim of this study was to evaluate the incidence and morphologic characteristics of osteochondral lesions of the distal tibial plafond (OLTP) by location and morphologic characteristics on MRI. Material and Methods: We assigned 9 zones to the distal tibial plafond articular surface in an equal 3×3 grid configuration. Zone 1 was the most anterior and medial, zone 3 was anterior and lateral, zone 7 was most posterior and medial, and zone 9 was the most posterior and lateral. The grid was designed with all 9 zones being equal in surface area. Two observers reviewed MRI examinations of 38 patients (12 males and 26 females; mean age, 38.7 years; age range, 10 to 68 years) with reported OLTPs. We recorded the frequency of involvement and size of lesion for each zone. A chart review was performed. Results: Of the 38 OLTP found in this study, 14 (37%) of the lesions were on the medial tibial plafond [zones 1, 4 and 7] and 11 (29%) involved the lateral tibial plafond [zones 3, 6 and 9]; 13 lesions (34%) localized to the center third of the plafond [zones 2, 5 and 8]. Nine of the lesions (24%) were on the anterior tibial plafond [zones 1, 2 and 3], 15 lesions (39%) predominately involved the posterior plafond [zones 7, 8 and 9], and 14 lesions (37%) localized to the central third of the plafond [zones 4, 5 and 6]. The medial central tibial plafond was most frequently involved site with 8 of the 38 (21%) lesions located there; the posterior medial tibial plafond was second most frequently involved with six of the 38 lesions (16%). Six of 38 ankles had both a talar osteochondral lesion and an OLTP. Of these, only one was a ‘kissing’ lesion. Chart review revealed that all subjects had ankle pain at time of MRI examination. Conclusion: We conclude that osteochondral lesions of the distal tibial plafond must be considered in the differential diagnosis of patients with symptomatic ankles and that no location had a significantly higher incidence.