Posterior tibial tendon dysfunction: Clinical and magnetic resonance imaging findings having histology as reference standard

Objective: To investigate the correlation between MRI, clinical tests, histopathologic features of posterior tibial tendon (PTT) dysfunction in patients with acquired adult flatfoot deformity surgically treated with medializing calcaneal osteotomy and flexor digitorum longus tendon transposition. Materials and methods: Nineteen patients (11 females; age: 46 +/- 15 year, range 18-75) were pre-operatively evaluated using the single heel rise (HR) and the first metatarsal rise (FMR) sign tests. Two reviewers graded the PTT tears on a I-III scale and measured the hindfoot valgus angle on the pre-operative MRI of the ankle. The specimens of the removed portion of PTT were histologically analysed by two pathologists using the Bonar and Movin score. Linear regression, Spearman's rank-order, and intraclass correlation coefficient (ICC) statistics were used. Results: ICC for MRI was excellent (0.952). Correlation between FMR and HR tests was at limit of significance (r=0.454; P=0.051). The HR and FMR tests were significantly correlated to the Movin score (r=0.581; P=0.009 and r=0.538; P=0.018, respectively) and were not significantly correlated to the Bonar score (both with a r=0.424; P=0.070). PTT tendinopathy grading at MRI was significantly correlated to the FMR test (p=0.041) but not to the hindfoot valgus angle (p=0.496), the HR test (p=0.943), the Bonar score (p=0.937), and the Movin score (p=0.436). The hindfoot angle was not correlated to any of the other variables (p>0.264). Conclusion: For PTT dysfunction, there is high correlation between HR and FMR test and histology evaluated using the Movin score, while no correlation was seen for the Bonar score. Semiquantitative grading of PTT dysfunction at MRI only correlates to the FMR and not to histology. The hindfoot valgus angle is not correlated to any of the considered variables.