Müller Weiss Disease: Radiological Evaluation and Proposed Treatment Algorithm

CATEGORY: Midfoot/Forefoot INTRODUCTION/PURPOSE: Müller Weiss disease is becoming increasingly recognized and is of unknown etiology. Maceria et al. formulated a classification based upon the Méary-Tomeno talo-first metatarsal angle and coined the term ‘paradoxical pes planus varus’ proposing hallmark deformities. Acknowledging there is no gold standard for treatment, various surgical modalities have been advocated in the literature e.g. isolated lateral displacement calcaneal osteotomy as sole treatment. The question subsequently arises; which joints to fuse in Muller-Weiss disease? Although no consciences prevails, one must postulate fusion should include those affected. For the purpose of establishing an algorithm in the surgical treatment of Muller-Weiss disease, we therefore set out to study its clinical and radiographic features, including pathoanatomy and metabolism as determined by SPECT- CT. METHODS: We studied 63 consecutive feet presenting with Muller-Weiss disease (15 to 86 years, 18 men, 26 women). History and examination by consultant in all cases. Plain radiographs included standing anteroposterior both ankles, hindfoot alignment views, lateral standing of both ankles and feet, medial oblique both feet and dorsoplantar standing and SPECT-CT. Surgery performed on significantly symptomatic feet unresponsive to minimum of six months conservative measures. Méary’s talo-first metatarsal angles measured. On dorsoplantar radiographs the anteroposterior thickness of the navicular was measured at each naviculo-cuneiform joint perpendicular to transverse axis of the medial pole of the navicular. The percentage compression was calculated at each joint and the degree of extrusion of the medial pole. Hindfoot alignment measured using method of Saltzmann. Study approved by our local research and ethics department and in accordance with General Data Protection Regulation guidelines. Statistical analysis was performed using SPSS software. RESULTS: Using R2 coefficient of determination we found no correlation at any level between extrusion and the degree of compression. With respect to hindfoot alignment and Méarys angle there was no significant correlation (R2=0.003) Shapiro-Wilk test demonstrates a normal distribution of extrusion in both unilateral and bilateral cases. In 95.2% of unilateral cases extrusion significantly greater on affected side (P<0.001 Fisher exact test), in bilateral cases extrusion greater on the side with more compression 55.6%. Degree of extrusion significantly greater in bilateral than in unilateral cases (P=0.004 unpaired T-test) ‘Paradoxical pes planus varus’ present in 27% with heel valgus and Méary’s negative in 47% cases. Almost half of patients treated conservatively consistent with literature with surgical intervention specific to involved joints from clinical and radiological parameters. CONCLUSION: Lack of correlation between Méary angle and degree of compression or extrusion invalidates principle classification; it fails to reflect the severity of compression of the lateral navicular and amount of extrusion of the medial pole and has no prognostic value. It provides no guide as to what joints to fuse. Proposed hallmark deformities only present in 27% of advanced disease therefore caution advised with surgical modality. SPECT-CT influenced operative planning and authors advocate its use. We observed greater incidence of fracture with advanced disease and subclinical degenerative changes. With failed non-operative management figure 1 is our proposed treatment algorithm.