Purpose: Necrosis of the navicular bone, described by Müller then Weiss in 1927, is an uncommon finding, unlike talonavicular degeneration which is a rather frequent complication of talipes planovalgus. Between 1985 and 2000, we cared for 25 patients with this condition. The purpose of this retrospective analysis was to describe the clinical and radiological presentation and attempt to reconstruct its natural history with the aim of determining therapeutic indications.
Material and methods: We analysed 25 cases of navicular bone necrosis observed in 14 women and 3 men (eight bilateral cases). Mean age of the patients was 39 years (range 16–59). The diagnosis of necrosis was established on the basis of structural alterations (densification, bone defects) and in the more advanced cases, flattening and “expulsion” of the navicular bone. We looked for clinical signs and described the radiological aspect of the necrotic zone. A computed tomography was available in 14 cases and magnetic resonance imaging in the five most recent cases.
Results: Pain was the major sign in all cases. One-third of the cases occurred in a foot with prior planovalgus. History taking revealed elements suggestive of an aetiology in three cases: probable Köhler-Mouchet disease in a 16-year-old boy, sickle cell disease in a 35-year-old man, and prolonged walking with signs suggesting stress fracture in a 40-year-old woman. In the other 19 cases (11 women and 1 man, 7 bilateral cases), necrosis was considered idiopathic. Radiologically, we used the Ficat classification (described for hips): stage 0 with normal x-ray and strong uptake on scintigram (n=1), stage 1 with a normally shaped navicular bone but condensation or bone defect, stage 2 with modification of the shape of the bone without signs of degeneration, stage 3 where changes in the shape of the bone are associated with narrowing of the talonavicular then cuneonavicular space. Computed tomography included frontal and horizontal slices as well as lateral reconstructions indispensable to assess the posterior part of the interarticular spaces. Treatment was surgical in 12 cases and medical in 13. Well tolerated forms were treated with plantar ortheses with regular surveillance. Surgical procedures included triple arthrodesis (early in our experience), mediotarsal arthrodesis (n=2), talonavicular arthrodesis (n=7) and talocuneate arthrodesis with replacement of the scaphoid by an iliac graft (n=2). The natural course of necrosis was studied in the cases without surgery. The first sign was medial mediotarsal pain. At this stage scin-tigraphy or MRI was required for positive diagnosis. At stage 0 condensation of the navicular bone, confirmed by computed tomography, preceded bone flattening then expulsion upwardly and medially, sometimes with fragmentation and onset of talonavicular degeneration. Cuneonavicular degeneration appeared to occur later (except in one case). Long-term results of surgery were good with pain relief and renewed activity.
Discussion: The clinical presentation initially described as Müller-Weiss disease or scaphoiditis, which concerns a bilateral condition generally occurring after trauma and sometimes with a favouring factor (alcoholism, osteoporosis), appears somewhat different from our description. Mechanical factors predominated in our patients and the aetiologies were quite similar to those observed in Kienböck syndrome. Excessive pressure on the navicular bone, which leads to avascular necrosis, flattening, and expulsion, is undoubtedly the essential cause of this condition. It is well tolerated in some individuals and can lead to spontaneous fusion. In this situation, treatment can be limited to surveillance or orthopaedic care. If the functional impact is important, surgical treatment can be proposed, generally limited to talonavicular arthrodesis. If the navicular bone is sclerosed and flat, the remaining fragment can be replaced by an iliac graft to achieve talocuneate fusion.
Conclusion: Necrosis of the navicular bone appears to be less uncommon than in the classical description, particularly in black women aged 25–50 years. A more precise study of favouring anatomic factors (length of the medial ray, size of the talar neck, depression of the medial arch) could provide further information concerning the aetiology which appears to be similar to that of Kienböck disease.
