Pseudolesion of the Distal Tibia Articular Surface: Frequency and Morphological Criteria in Magnetic Resonance Imaging

Purpose or Learning Objective: To report the prevalence and describe magnetic resonance imaging (MRI) findings of a previously unreported chondral pseudolesion of the distal tibia, and to define criteria to distinguish it from pathologic osteochondral lesions in this area.

Methods or Background: A multicentric retrospective case-control study included a total of 2,428 ankle MRI examinations performed over 6 years. MRIs were evaluated by two readers in consensus for cartilage irregularity of the distal tibial articular surface. For this purpose, the tibial articular surface was divided into nine topographic regions. Proton-density-weighted fat-suppressed sequences in sagittal and coronal acquisition were used to assess the posteromedial articular surface of the tibia.

Imaging features, such as size and localization of cartilage irregularity and/or a cortical mold, as well as the presence of associated edema and/or subchondral cysts, were reported. Demographic data, such as sex, age, and weight of the patients, were also recorded. Clinical data analyzed were presence of pain, movement impairment, and concomitant pathologies.

Results or Findings: Of 2,428 patients, a total of 68 (34 male, 34 female) with a lesion of the distal tibia were included to evaluate if a pseudolesion could be present (prevalence: 2.8%). These lesions presented with cartilage irregularity and/or subchondral alterations such as edema or cysts. Mean body weight was 77.6 ± 11.4 kg (range: 45–107 kg). These lesions occurred most frequently (74%) in the posteromedial distal tibia plafond and were more commonly detected (47%) in the age group of 9 to 30 years.

In 17 of these cases, the cartilage irregularity was the only lesion without subchondral abnormalities, and this pseudolesion had a prevalence of 0.5%. Most (85%) were detected in the posterior part, especially in the posteromedial part (55%) of the distal tibia. In 36 of 68 cases, we observed, in addition to cartilage irregularity, subchondral alterations such as edema (86%) and/or cysts (44%). These alterations were more commonly in the posteromedial distal tibia: in 33 of the 40 cartilage irregularities (or in 82.5% of cartilage irregularities). The size of the cartilage defect ranged from 1 to 7 mm; most (69%) were 2 to 3 mm. Subchondral edema was observed in most of the patients (65%). Less prevalent were subchondral cysts (31% of cases). No significant association was found between the presence of motion-related pain and imaging findings of cartilage irregularity, subchondral edema, and subchondral cysts. In 19 of 68 patients, no measurable chondral irregularity was found, but a cortical mold into which the cartilage bulges and adjacent subchondral phenomena such as edema or cyst were noted.

Conclusion: An osteochondral lesion or chondral lesion in the posteromedial aspect of the distal tibia articular surface could be a pseudolesion. Its identification is essential because it will have therapeutic implications.

Publication History

Article published online:
02 June 2022