Therapeutic efficacy analysis of distal tibia varus syndrome with different classification and different therapy: a cross-sectional study

BACKGROUND: We often attribute the lateral ankle impingement to the valgus calcaneus, while ignoring the varus distal tibia. The diagnostic criteria, severity and treatment of distal tibia varus syndrome (DTVS) have not been reported. This retrospective study sought to propose a diagnosis and classification system for DTVS based on patients’ clinical symptoms and imaging findings. METHODS: A total of 76 symptomatic patients with varus distal tibia and congruent ankle examined between 2010 and 2018 were involved to evaluate clinically based on their SF-36 scores, AOFAS ankle-hindfoot scores, and VAS scores. Each patient’s history, symptoms, and MRI images were analyzed retrospectively, and their weight-bearing ankle radiographs were observed to measure the tibial anterior surface angle (TAS) and tibial tilt angle (TTA). Paired t-test and Kruskal-Wallis test were used to compare the results above. RESULTS: Forty-three men and 33 women with an average age of 46 years (range, 28−68 years) included. Besides the same symptom of intermittent subfibular pain, 3 types of DTVS were defined: (I) Type I: a sloped surface of the distal tibia with the congruent tibiotalar joint on radiographs; (II) Type II: a sloped surface of the distal tibia with the congruent tibiotalar joint on radiographs, and soft-tissue edema inferior to the lateral malleolus on MRI images; and (III) Type III: the same symptoms as Type II, plus osteochondral lesions of the talus on MRI images. Under our proposed classification system, 26 patients were classified as Type I, requiring conservative treatment, 22 as Type II, and 28 as Type III under supramalleolar valgus osteotomy. The ankle functional evaluation scores, such as the SF-36 (74.14±12.50 preoperatively and 85.22±8.83 postoperatively), AOFAS (71.14±15.19 preoperatively and 87.53±8.62 postoperatively), and VAS (5.41±1.10 preoperatively and 1.82±1.08 postoperatively) scores for all types were significantly improved (P<0.01). The TAS (80.38°±4.80° preoperatively and 90.44°±3.96° postoperatively) and TTA (13.02°±3.41° preoperatively and 0.62°±2.67° postoperatively) of all the patients on the weight-bearing ankle radiographs were significantly improved (P<0.01). CONCLUSIONS: DTVS, causing lateral ankle impingement, can be diagnosed based on clinical manifestations and imaging findings. Our classification system can aid in the decision-making process in relation to the appropriate form of conservative or surgical treatments.