Flatfoot in Müller-Weiss syndrome: a case series

INTRODUCTION: Spontaneous osteonecrosis of the navicular bone in adults is a rare entity, known as Müller-Weiss syndrome. We report here on our experience with six patients with Müller-Weiss syndrome accompanied by flatfoot deformity, but on a literature search found no reports on this phenomenon. Because the natural history and treatment are controversial, an understanding of how to manage this deformity may be helpful for surgeons when choosing the most appropriate operative procedure. CASE PRESENTATION: Six patients (five women, one man; average age, 54 years) with flatfoot caused by osteonecrosis of the navicular bone were followed up between January 2005 and December 2008 (mean follow-up period, 23.2 months). Conservative treatment, such as physical therapy, and non-steroidal anti-inflammatory drugs were used, but failed. Physical examinations revealed flattening of the medial arch of the involved foot and mild tenderness at the mid-tarsal joint. Weight-bearing X-rays (anterior-posterior and lateral views), computed tomography, and MRI scans were performed for each case. Talonavicular joint arthrodesis was performed in cases of single talonavicular joint arthritis. Triple arthrodesis was performed in cases of triple joint arthritis to reconstruct the medial arch. Clinical outcomes were assessed using the American Orthopaedic Foot and Ankle Society ankle-hindfoot scale; the scores were 63.0 pre-operatively and 89.8 post-operatively. All patients developed bony fusion. CONCLUSIONS: The reason for the development of flatfoot in patients with Müller-Weiss syndrome is unknown. Surgical treatment may achieve favorable outcomes in terms of deformity correction, pain relief, and functional restoration. The choice of operative procedure may differ in patients with both flatfoot and posterior tibial tendon dysfunction.