Review Question - QID 212199

Hindfoot nailing is appropriate in cases of stage IV posterior tibial insufficiency (PTTI), but if the lateral to medial interlocking screw in the calcaneus is left long, it can impinge on the flexor hallucis longus (FHL), causing difficulty with hallux flexion.

PTTI is a common cause of adult flatfoot deformity, particularly in older women. The initial insufficiency of the posterior tibial tendon leads to collapse of the arch, and eventually becomes a rigid deformity which is not passively correctable. In these situations, osteotomies are often performed to move the calcaneus medially in combination with tendon transfers. In this patient, deltoid ligament compromise is also noted, with rigid valgus deformity at the ankle, causing her deformity to be classified as stage IV PTTI. This, combined with arthritis at the ankle joint, makes her a better candidate for talotibial calcaneal arthrodesis, often performed using a retrograde hindfoot nail. Common complication include lateral plantar nerve irritation and FHL impingement if interlocking screws are inappropriately sized, therefore attention should be paid to these details.

Deland provides a review of adult-acquired flatfoot deformity, noting that it was initially described as PTTI, but also encompasses other deformities. Early diagnosis and appropriate management is helpful in treating symptoms and progression. If surgery is necessary, the goal is to improve alignment of the foot, while maintaining as much flexibility as possible.

Haddad et al. provides an overview of the management and treatment of acquired flatfoot deformity. They note that much of the controversy revolves around stage II deformities, as surgical options are more broad with the foot remaining flexible. They go on to describe, at length, the different surgical options and tips/tricks associated with each technique.

Figure A is an AP radiograph of an ankle after hindfoot nail with evidence of the lateral to medial distal interlocking screw being slightly too long adjacent to the sustentaculum.

Incorrect Answers:
Answer 2: Lateral planter nerve irritation is common in hindfoot nailing, but would not be affected by interlocking screw positioning, rather, the starting point of the nail.
Answer 3: The tibialis anterior tendon would not be affected by a lateral to medial interlocking screw.
Answer 4: Saphenous vein is more superficial medially and unlikely to be penetrated by a lateral to medial interlocking screw.
Answer 5: The tibial nerve does also sits more anterior to the FHL and is not as intimately associated with the sustentaculum as the FHL.