Review Question - QID 219437

First tarsometatarsal fusion (Lapidus procedure), in isolation, can correct the valgus of the first ray but fails to fully correct pathologic pronation. The addition of a modified McBride procedure, which includes a release of the adductor from the lateral sesamoid, a lateral capsulotomy, and medial capsular imbrication, corrects this deformity by de-rotating/supinating the first ray (Answer 3).

Hallux valgus, commonly referred to as a bunion, is a complex valgus deformity of the first ray. This pathology occurs more frequently in females and has a variety of intrinsic and extrinsic risk factors for development including, but not limited to, genetic predisposition, ligamentous laxity, pes planus, and wear of shoes with a high heel and narrow toe box. Patients often present with difficulty with shoe wear, and a painful prominence at the first metatarsophalangeal (MTP) joint.

The development of Hallux valgus follows a predictable pathoanatomic cascade. First, valgus deviation of the phalanx promotes varus positioning of the metatarsal. The metatarsal head then displaces medially, which leaves the sesamoid complex laterally translated relative to the metatarsal head. The medial MTP capsule becomes stretched while the lateral capsule becomes contracted. As the deformity continues, plantar and lateral migration of the abductor hallucis causes the muscle to plantarflex and pronate the phalanx, leading to a rotational (in addition to valgus) deformity (Illustration A).

A variety of surgical procedures are utilized to correct hallux valgus. First tarsometatarsal arthrodesis (Lapidus procedure), when indicated, can correct the underlying valgus deformity but, in isolation, fails to fully correct the underlying rotational deformity. As a result, this procedure is now routinely performed alongside a modified McBride procedure, which corrects first ray pronation through derotation via supination.

Conti et al. investigated the effect of the addition of a McBride procedure to a Lapidus procedure on the correction of first ray pronation in the setting of hallux valgus. Their study included 31 patients. Overall, the authors concluded that the addition of the McBride procedure was able to correct approximately 10° of pathologic pronation of the first ray.

Scheele et al. investigated the bony forefoot geometry following Lapidus with modified McBride. Their study included 30 patients with a mean age of 63.2 years. The authors concluded that the addition of a McBride procedure allowed for the recentering of the sesamoids under the first metatarsal head.

Illustration A is a graphical representation of the pathophysiologic cascade of Hallux valgus, as described above.

Incorrect Answers:
Answer 1: Lateral, not medial, capsulotomy is a component of the McBride procedure. Medial capsulotomy would worsen the underlying valgus deformity.
Answer 2: Medial, not lateral, capsular imbrication is a component of the McBride procedure. Lateral capsular imbrication would worsen the underlying valgus deformity.
Answer 4: Resection of the base of the proximal phalanx is known as a Keller resection arthroplasty, and its use has been largely abandoned.
Answer 5: Release of the adductor from the lateral sesamoid is a component of the modified McBride procedure.