Cartilage Matrix Changes in Hindfoot Joints in Chronic Ankle Instability Patients After Anatomic Repair Using T2-Mapping: Initial Experience With 3-Year Follow-Up

Abstract

Background: Anatomic repair is widely accepted as the primary surgical treatment for chronic lateral ankle instability (CLAI). T2-mapping is a powerful tool for quantitative assessment of biochemical changes in cartilage matrix.

Purpose: To longitudinally evaluate cartilage matrix changes in the hindfoot joints of CLAI patients before and after anatomic repair by using T2-mapping with magnetic resonance imaging (MRI).

Study type: Prospective.

Subjects: Thirty-two CLAI patients (males/females = 20/12) and 21 healthy controls (males/females = 13/7).

Field strength/sequence: 3 T; sagittal multi-echo spin-echo technique (T2-mapping), coronal, sagittal, and axial spin-echo PD-FS, and sagittal T1WI sequences.

Assessment: MRI examinations were performed in CLAI patients at baseline (prior to surgery) and 3 years after anatomic repair and in healthy controls. On T2-maps, the hindfoot joints were segmented into 16 cartilage subregions. The T2 value of each subregion was measured. All patients were evaluated with the American Orthopedic Foot and Ankle Society (AOFAS) scale at baseline and after surgery.

Statistical tests: Analysis of variance (ANOVA) and Student's t-test were used. The differences corresponding to P < 0.05 were considered statistically significant.

Results: At baseline, the T2 values in most cartilage subregions of talar dome and medial posterior subtalar joint (pSTJ) were higher in CLAI patients than in healthy controls. After surgery, only the T2 value of anteriomedial talar dome decreased from that at baseline (31.11 ± 3.88 msec vs. 34.27 ± 5.30 msec). The T2 values of other subregions with elevated T2 values remained higher than healthy controls. There were no significant differences in T2 values in the midtarsal joints between CLAI patients and healthy controls (P = 0.262, 0.104, 0.169, 0.103). Postoperatively, the patients' AOFAS scores improved significantly from 67.81 to 89.13.

Data conclusion: CLAI patients exhibited elevated T2 values in most subregions of talar dome and medial pSTJ. After anatomic repair, although the patients exhibited good clinical outcomes, the elevated T2 values could not be fully recovered.

Level of evidence: 2 TECHNICAL EFFICACY STAGE: 4.

Keywords: T2-mapping; anatomic repair; ankle instability; cartilage.