The Windswept Foot: Dealing with Metatarsus Adductus and Toe Valgus

Anatomy, Biomechanics, and Pathogenesis of the Lesser Toes Deformities

Deformities of the lesser toes are a prevalent condition faced by orthopedic surgeons. An imbalance between the extensor and flexor muscles might cause these deformities, affecting the metatarsophalangeal joint (MTPJ) and interphalangeal joint (IPJ). Therefore, a thorough understanding of the anatomy, biomechanics of the MTPJ, the surrounding structures, and the pathogenesis of lesser toe deformities is crucial for ensuring the correct diagnosis and treatment of the deformities. Maintaining foot biomechanics during the different gait phases preserves the development and progressive evolution of deformities.

Ultrasonography-Based Quantitative Evaluation of Second Metatarsophalangeal Joint Instability in Female Patients With Hallux Valgus

BACKGROUND

Patients with moderate to severe hallux valgus (HV) sometimes exhibit second metatarsophalangeal (MTP) joint dislocation. Second MTP joint instability due to plantar plate (PP) injury has been suggested as one of the causes. However, there have been no reports that quantitatively evaluate this instability. This study aimed to evaluate second MTP joint instability in patients with HV without dislocation via ultrasonography and investigate its relationship with the presence of PP injury or foot form.

METHODS

Between May 2018 and July 2023, symptomatic female patients with HV without any lesser toe deformity were included in this study. Second MTP joint instability was defined as the dorsal displacement ratio (DDR) of the passively subluxated proximal phalangeal articular surface on the metatarsal head articular surface. The presence of PP injury was assessed using ultrasonography. Foot "form" was determined by measuring standard foot bony angles on weight-bearing foot-ankle radiographs. The relationship between DDR or PP injury and radiographic measurements was investigated.

RESULTS

Sixty-four patients (100 feet) were included. The average DDR of the second MTP joint in patients with HV without dislocation was 35.7%. There was an increase in the probability of PP injury, above a cutoff DDR value r of 35.4% (area under the curve = 0.712). The sensitivity, specificity, positive predictive value, and negative predictive value for the presence of PP injury based on this cutoff level were 63.9%, 74.4%, 79.6%, and 56.9%, respectively. Metatarsalgia was reported in 21 feet (21.0%), of which 15 feet (71.4%) showed PP injury. An increase in DDR was weakly associated with increased metatarsus adductus angle and decreased second metatarsal height.

CONCLUSION

In female patients with HV without second MTP dislocation, we found ultrasonographic evidence of second MTP plantar plate injury and joint instability to be a relatively common finding with a high prevalence in those with localized metatarsalgia.

LEVEL OF EVIDENCE

Level II, development of diagnostic criteria based on consecutive patients.

Improvement of Valgus Deviation of the Lesser Toes of Moderate to Severe Hallux Valgus After Proximal Chevron Metatarsal Osteotomy and Akin Osteotomy

BACKGROUND

This study examines the correction of lesser toe valgus deviation following proximal chevron metatarsal osteotomy (PCMO) and Akin osteotomy in moderate to severe hallux valgus patients, while identifying influencing factors.

METHOD

Among 89 patients (116 feet), those with moderate to severe hallux valgus underwent PCMO and Akin osteotomy. Radiologic assessments included preoperative metatarsus adductus angle (MAA), hallux valgus angle (HVA), intermetatarsal angle (IMA), valgus angles of the second to fourth metatarsophalangeal joints, and hallux valgus recurrence. Assessments included visual analog scale (VAS) pain scores, American Orthopaedic Foot & Ankle Society (AOFAS) scores, and patient satisfaction over an average follow-up of 30.6 ± 21.2 (range, 12-99) months.

RESULTS

The mean preoperative HVA of 34.4 degrees decreased to 8.7 degrees at final follow-up. The valgus angles of the second, third, and fourth toes improved by 37.1%, 27%, and 44.5%, respectively. In metatarsus adductus patients, lesser toe valgus angles were significantly higher both preoperatively and at final follow-up. Hallux valgus recurrence patients had higher preoperative and final follow-up IMA and valgus angles in the second and third toes. Nonrecurrence patients showed greater decreases in these angles. A larger HVA correction corresponded to a greater decrease in lesser toe valgus deviation. VAS and AOFAS scores improved significantly at the last follow-up.

CONCLUSION

The study found a significant reduction in the valgus angle of the second, third, and fourth toes after PCMO and Akin osteotomy in moderate to severe hallux valgus cases, without additional surgeries on lesser toes. The lesser toe angular reductions were less pronounced in patients with metatarsus adductus or with hallux valgus recurrence.

LEVEL OF EVIDENCE

Level IV, case series.