A 70-year-old woman presented with a 10-month history of left midfoot pain without any trauma. She was diagnosed as having osteonecrosis of the tarsal navicular based on the findings of plain radiographs from the previous hospital. She was initially treated with an insole. However, the conservative treatment was ineffective for her symptoms. Therefore, surgery was performed.
At the time of presentation, her left foot was swollen and had point tenderness at the dorsal side of the talonavicular joint. The preoperative Japanese Society for Surgery of the Foot (JSSF) midfoot scale score was 79 points. Radiographs showed increased radiodensity and dorsal protrusion of the tarsal navicular. Sclerotic collapse was also noted at the lateral aspect of the tarsal navicular (Figure 1). Computed tomography (CT) scans showed diffuse sclerosis and marginal irregularities of the tarsal navicular (Figure 2). Magnetic resonance imaging (MRI) showed low signal-intensity areas on both T1-weighted images and T2-weighted images in the marrow of the tarsal navicular. Gd-based MRI showed increased uptake in the peripheral tarsal navicular, which was representative of hypervascular areas (Figure 3). She was diagnosed with spontaneous osteonecrosis with a Maceira classification of Stage 3.
Arthrodeses of the talonavicular and naviculocuneiform joints were selected as the treatment because both joints had cartilage damage on imaging. The articular surfaces of the talus and medial cuneiform that were adjacent to the tarsal navicular and necrotic areas of the tarsal navicular were excised. The blood supply was visible from the marrow of the residual tarsal navicular. The bone defect (5 cm x 1 cm) was reconstructed with a tricortical bone graft harvested from the iliac crest. Arthrodesis was performed using an LCP Distal Radius Plate (SYNTHES) with 6 2.4 mm locking screws from the medial aspect of the foot (Figure 4). Histopathologic findings showed diffuse empty lacunae without any infection, consistent with avascular necrosis (Figure 5). The ankle was immobilized in a cast for 4 weeks after surgery. Partial weight bearing with a patellar tendon-bearing (PTB) orthosis was permitted after the removal of her cast.
A radiograph taken 1 year after surgery showed union of the naviculocuneiform joint, but she did not have satisfactory union of the talonavicular joint. The patient had referred pain with the backing out of the most proximal screw. Therefore, the most proximal screw was removed. A radiograph taken 5 years after surgery showed nonunion with mild osteoarthrosis of the talonavicular joint (Figure 6). However, she just had tenderness of the talonavicular joint and had no pain in her usual daily life. The final follow-up JSSF midfoot scale score was 97 points.