Impact of Flexor Hallucis Longus Retrotalar Pulley Release on First Ray Joint Pressures in Functional Hallux Limitus: A Cadaveric Study

Abstract

Background:

This cadaveric study aimed to assess the biomechanical impact of functional hallux limitus (FHLim), identified using the functional stretch test, on first metatarsophalangeal joint (MTP1) mobility and joint pressures, as well as on the first cuneometatarsal joint (C1M1). A secondary objective was to evaluate the effect of retrotalar pulley section of the flexor hallucis longus (FHL) tendon on these parameters.

Methods:

Seventeen cadaveric feet from 9 donors were analyzed. Each specimen was assessed in a resting position and during a functional stretch test, defined as passive hallux dorsiflexion performed with the ankle maintained in dorsiflexion to reproduce functional loading conditions. MTP1 mobility and intraarticular pressures at the MTP1 and C1M1 joints were measured before and after sectioning of the FHL retrotalar pulley.

Results:

Maximum dorsiflexion mobilities in stretch test position in the FHLim group were significantly increased after pulley section (P < .001). Increased MTP1 pressure was found in the stretch test position in case of FHLim compared with controls in the neutral position (P = .02), and in the 20° dorsiflexion position (P = .02). There was a greater differential pressure in C1M1 joint before/after sectioning of the pulley in the FHLim group, whatever the position of the MTP1 in stretch test (P < .05). The amount of pressure reduction in MTP1 joint after pulley section in dorsiflexion was correlated with the severity of maximal dorsiflexion deficit in the stretch test position before pulley section (r = 0.51; P = .04).

Conclusion:

In this cadaveric model, FHL tenodesis at the retrotalar pulley restricted functional MTP1 dorsiflexion and increased joint pressures. Retrotalar pulley section corrected this biomechanical constraint and normalized MTP1 pressures relative to controls, supporting its role as a contributing mechanism in functional hallux limitus.

Clinical Relevance:

This cadaveric study provides direct biomechanical evidence linking FHL retrotalar pulley impingement to elevated MTP1 joint pressures, supporting pulley release as a rational surgical target in functional hallux limitus.