Fig. 8.1
Reverse Coleman block test . The block is place under the first metatarsal head, (a) and the block height is adjusted until the heel valgus is corrected (b) (Adapted from: Wood et al. [18])
Fig. 8.2
A weight-bearing lateral x-ray depicting a sag at the naviculocuneiform joint in a planovalgus foot (a). After placement of a reverse Coleman block, the hindfoot is corrected to neutral, and the deformity at the naviculocuneiform joint is better appreciated (b) (From: Ajis and Geary [19])
Correction of cavus foot deformities through the NC joint has also been described. Giannini et al. utilized a combination of a plantar fasciotomy, closing wedge osteotomy through the NC joint complex, and closing wedge osteotomy through the cuboid to correct deformity in patients with idiopathic cavus [11]. Using a similar technique, Faldini et al. [12] reviewed the results of 24 cavus feet in 12 patients with Charcot-Marie-Tooth disease. Only patients with a flexible deformity and no significant arthritis were included. Results were reported as excellent in twelve feet (50%), good in ten (42%), and fair in two (8%).
Medial NC joint coalition is generally considered a rare condition and sparsely reported in the literature [5–10], but some authors believe it may be more prevalent than once thought [7]. Up to half of patients may be asymptomatic with the condition being found incidentally. Symptomatic patients generally experience plantar medial midfoot pain. Conservative management works well for the majority of patients. Surgical intervention is considered in those with persistent pain symptoms. Surgical options include resection of the coalition or primary fusion with or without bone graft with no gold standard agreed on.
Mueller-Weiss disease is characterized by flattening or fragmentation of the lateral aspect of the navicular. Its etiology is not entirely clear but osteonecrosis, congenital dysplasia, remote trauma, and overuse have been proposed [4]. The condition afflicts females disproportionately and typically presents with chronic midfoot or hindfoot pain. Many cases are treated satisfactorily with appropriate shoe wear and orthotics. Those who fail nonoperative measures are considered surgical candidates. Navicular bone fixation, talo-naviculocuneiform fusion , and triple arthrodesis have all been described, but the best operative management has not been established [2–4].
Contraindications
Arthrodesis of the NC joint is contraindicated in the setting of inadequate perfusion and/or active infection.
In the setting of Charcot neuroarthropathy and advanced deformity, an isolated NC arthrodesis may be insufficient. In this situation, an extended medial column arthrodesis is usually necessary.
Pearls and Pitfalls
A ratcheted distraction device (e.g., a Hintermann distractor) is particularly helpful for fully exposing the joint(s) to be fused.
In arthritic situations, the use of a preoperative, diagnostic anesthetic arthrogram is helpful in confirming that the NC joint is the primary pain generator.
If the NC joint is not the only pain generator (e.g., with inflammatory arthritis) or there is instability through the talonavicular and tarsometatarsal joints, then consideration should be given to extending the arthrodesis.
In the setting of poor bone stock, medial or plantar plating may provide biomechanical advantages with regard to internal fixation.
Approaches and Techniques
A popliteal and saphenous nerve block are typically administered in the preoperative area. The patient is positioned supine on the operating room table. In cases where an NC arthrodesis is to be performed as part of a more elaborate planovalgus or cavus deformity correction , the surgeon should consider placing a bump under the ipsilateral hip to encourage a more vertical foot position that allows for easier access to the lateral side. For more straightforward cases, such as an in situ fusion for arthrosis, the extremity can be allowed to fall into its natural externally rotated position. A midcalf tourniquet can be applied if no tendon transfer or gastrocnemius lengthening procedures are planned. Otherwise a proximal thigh tourniquet is applied.
The naviculocuneiform joint complex can be approached either medially or dorsomedially (Fig. 8.3). This choice will largely be determined by other case factors. Both approaches utilize the interval between the tibialis anterior and posterior tibial tendons. The medial approach occurs roughly parallel to the posterior tibial tendon. The dorsomedial approach more closely follows the tibialis anterior tendon. In flatfoot reconstruction cases, where access to the posterior tibial tendon and flexor digitorum longus tendon are often required, the medial approach is recommended. Similarly, the medial approach is favored when a closing wedge osteotomy of the NC joint complex is planned. For isolated NC fusion or when access to both the TN and NC joints are required, the dorsomedial approach allows for easier access to the lateral aspects of these joints.
Fig. 8.3
Surgical markings show the medial (line marked A) and anteromedial (line marked B) approach to the naviculocuneiform joint complex
The medial navicular tuberosity is identified, and the incision is centered just distal to this location. Proximally, the incision follows the course of the posterior tendon approximately 5 mm above it. Distally, the incision follows the axis of the medial column. The marginal medial vein and the tibialis anterior tendon are retracted. Occasionally, the tibialis anterior tendon will need to be divided in a z-fashion and repaired later. Sharp subperiosteal dissection is carried out to expose the NC joint. Posts for the Hintermann retractor are placed in the medial cuneiform and navicular. A baby Hohmann retractor is positioned dorsally over the medial cuneiform to assure protection of the tibialis anterior tendon. The NC joint capsule is sharply taken down both medially and plantarly. While traction is slowly increased, the dorsal capsulotomy is performed. Visualization across all three NC joints can be achieved, but preparation of the lateral-most joint is a challenging exercise and, in most cases, probably not necessary. Curettes are used to remove remaining cartilage down to subchondral bone. The subchondral bone is feathered with a 4 mm osteotome or perforated with a 1.5 mm or 2.0 mm drill bit. The intercuneiform joints are not prepared. To achieve a reduction and correct existing malalignment, the retractor posts can be used to “joystick” the cuneiforms with the goal being to restore the talo-first metatarsal angle to a straight line. Alternatively, the Hintermann retractor can be left in place off tension and rotated to achieve the desired cuneiform position (Fig. 8.4). Dorsiflexion of the hallux will also encourage plantar flexion of the medial column. If correction is difficult, a more aggressive capsular release may be required.
