Review Question - QID 218601

This patient has likely developed iatrogenic hallux varus due to resection of the fibular sesamoid during hallux valgus correction.

Hallux valgus deformity is multiplanar in nature and can be complicated to treat. There are multiple surgical options that can be appropriate based on the location and severity of the deformity. The sesamoids play a role in overall muscular balancing forces placed on the hallux. The medial and lateral bands of the flexor hallucis brevis (FHB) encompass the tibial and fibular sesamoids, respectively. When dissecting along the lateral aspect of the first metatarsal, it is common to encounter the fibular sesamoid. If it is accidentally resected during dissection, it effectively releases the lateral slip of the FHB and there is an unopposed pull through the medial slip. This results in both medial rotatory and translatory force along the base of the proximal phalanx where the medial slip of the FHB inserts, leading to hallux varus deformity. Other potential causes of similar imbalances leading to hallux varus include over-resection of the medial 1st metatarsal head, excessive lateral capsular release, excessive medial capsule imbrication, and overcorrection of the 1st intermetatarsal angle. Management of hallux varus should begin non-operatively, with possible operative interventions ranging from lateral closing wedge osteotomy of the metatarsal/proximal phalanx to tendon transfers with medial capsule release.

Easley et al. discuss the pathomechanics, clinical assessment and nonoperative management of hallux valgus, noting that there are a wide variety of treatment strategies currently employed. They start by addressing the anatomic considerations of hallux valgus and the classic deformities which include the 1st MTP joint valgus, increased intermetatarsal angle, and associated pronation deformity. They go on to discuss how to properly examine these patients and then discuss nonoperative management strategies.

Shi et al. review operative management strategies for hallux valgus. They note that there is a general algorithm for treating these deformities, but the best treatment methods are still somewhat debated. In this article, they discuss different soft tissue procedures and osteotomies, which settings these would be used in, techniques, and associated complications.

Incorrect Answers:
Answers 1 & 2: Distal chevron and akin osteotomies are appropriate to use in the setting of hallux valgus and their exclusive use would not lead to hallux varus deformity. In rare cases, over-translation of the intermetatarsal angle or the hallux valgus interphalangeus (HVI) angle may alter the pull of the associated tendons and cause the toe to supinate and deviate medially.
Answer 4: A supination deformity typically accompanies hallux varus, therefore, it is unlikely that under-correction of the bunion pronation deformity led to hallux varus.
Answer 5: MTP joint arthritis can lead to lack of MTP joint range of motion but rarely causes a varus deformity, and the more likely cause would be a fibular sesamoid resection at the time of surgery.