Review Question - QID 214148

This patient has pes planus secondary to deformity at the navicular-cuneiform joint. Treatment should be deformity correction with a fusion of the involved joint.

Pes planus, adult-acquired flatfoot deformity (AAFD), is most often caused by posterior tibial tendon insufficiency (PTTI). It manifests by the collapse of the medial longitudinal arch of the foot and often has an associated valgus hindfoot deformity. Radiographically it is determined by the lateral talometatarsal angle greater than 4 degrees (Meary's Angle). Within the differential for AAFD however is a midfoot deformity. Classically on radiographs with PTTI driven AAFD there is dorsal subluxation of the navicular on the talus. This is differentiated from midfoot driven AAFD by cuneiform subluxation dorsally on the talus with the maintenance of alignment between the navicular and the talus. Treatment for midfoot AAFD is with realignment and fusion of the midfoot. Initial treatment for all types of AAFD is nonoperative with orthotics and physical therapy.

Chi et al. reviewed medial column stabilization, lateral column lengthening, and combined procedures for the treatment of AAFD secondary to PTTI. They found improved outcomes with both lateral and medial procedures for the treatment of PTTI with 88% having improved or completely resolved pain. Additionally they found greater correction of Meary's angle with combined procedures. They recommend combined medial and lateral procedures for the treatment of PTTI.

Greisberg et al. reviewed isolated naviculocuneiform and first tarsometatarsal fusions for the treatment of AAFD. They had 19 patients in their study. Postoperatively they had restoration of appropriate talo-metatarsal angles and calcaneal pitch. Additionally they found overall correction of forefoot abduction and arch restoration.

Figures A and B are an AP and lateral Xray of a left foot with midfoot arthritis, and arch collapse that is secondary to the dorsal subluxation of the navicular-cuneiform joint with intact talonavicular alignment on the lateral. Illustration A demonstrates the same Xray with a superimposed talometatarsal angle (Meary's angle).

Incorrect answers:
Answer 1: This would worsen the flatfoot deformity, and may be indicated for the treatment of a cavovarus foot deformity.
Answer 2 and 4: These are operative interventions for stage II PTTI with a flexible hindfoot.
Answer 3: This can be part of the treatment for stage III PTTI with a fixed hindfoot deformity.