Second metatarsophalangeal joint dislocation in hallux valgus: a radiographic study using a two-dimensional...

Area of Science:

• Orthopedics
• Podiatry
• Radiology

Background:

• Hallux valgus (HV) with second metatarsophalangeal (MTP) joint dislocation presents complex surgical challenges.
• Understanding the specific anatomical alterations in these feet is crucial for effective treatment.

Purpose of the Study:

• To analyze the anatomical structure of hallux valgus feet with second MTP joint dislocation.
• To utilize a 2-dimensional coordinate system for precise mapping and comparison of radiographic parameters.

Main Methods:

• Weightbearing foot radiographs of 49 HV feet with second MTP dislocation (group D), 68 HV feet without dislocation (group W), and 54 controls (group N) were analyzed.
• A 2D coordinate system mapped standardized points, comparing parameters like HVA, IMA, 2MTPA, MAA, and lengths of the first and second metatarsals and toes across groups.

Main Results:

• Group D feet exhibited a proximally translated second toe, a medialized first metatarsal base, and a lateralized great toe tip.
• The third toe's proximal phalanx head was lateral in groups D and W compared to controls.
• The M1/2 angle correlated with dislocation direction: higher angles resulted in medial/neutral deviation, lower angles in lateral deviation.

Conclusions:

• Second MTP joint dislocation in HV feet is associated with specific positional changes of the toes and metatarsals.
• The M1/2 angle is a key factor influencing the direction of dislocation.
• 2D coordinate mapping offers novel insights into foot anatomy, aiding future research and surgical optimization for improved patient outcomes.