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Muscle MRI Fat Fraction Before Surgery to Predict Strength Recovery After Foot-Drop Surgery in Charcot-Marie-Tooth Disease
Sponsor: Peking University Third Hospital
Summary
The purpose of this prospective observational cohort study is to determine whether the amount of fat inside the donor muscles before surgery, measured with a magnetic resonance imaging (MRI) technique called Dixon fat fraction (FF), can predict how much ankle dorsiflexion strength patients with Charcot-Marie-Tooth disease (CMT) recover after tibialis posterior tendon transfer surgery. CMT is an inherited nerve disease that weakens the feet and legs, causing foot drop and high-arched, inwardly turned feet. A common operation transfers the tibialis posterior tendon to the top of the foot to restore foot lifting; however, the transplanted muscle itself may be weakened by fatty degeneration, and surgeons currently have no objective way to know in advance how well the transferred muscle will work. We hypothesize that a lower preoperative fat fraction of the tibialis posterior (donor) muscle is associated with greater recovery of dorsiflexion strength after surgery. A total of 100 adults (18-55 years) with genetically confirmed CMT types 1A, 1X or 2A who are scheduled for individualized foot surgery that includes tibialis posterior tendon transfer will be enrolled at 4 foot-and-ankle centers in China. Within 1 month before surgery, participants will undergo a lower-leg MRI with a Dixon sequence to measure the fat fraction of 11 calf muscles. Participants will then be followed for 5 years (3 and 6 months, and 1, 2, 3, 4 and 5 years after surgery). At every visit, ankle dorsiflexion strength will be measured with a hand-held dynamometer and normalized to body weight (newtons per kilogram); walking ability (1-minute walk distance, 10-meter walking speed), ankle range of motion, clinical severity scales (CMTES, Walk-12, FADI, SF-12) and CMT-related symptoms (pain, fatigue, cramps, balance and falls, sensory loss, hand function, brace use, calluses, mood) will also be assessed. Surgical details of every additional procedure will be recorded. The primary analysis will correlate preoperative tibialis posterior fat fraction with the change in dorsiflexion strength at each time point (principal endpoint: 12 months), and will test whether fat fraction independently predicts strength recovery in a multivariable regression model. If confirmed, preoperative muscle fat fraction could become an objective, readily available imaging marker to help surgeons select patients, choose between tendon transfer alternatives, and counsel patients about expected outcomes.
Official title: Preoperative Donor Muscle Fat Fraction Predicts Dorsiflexion Strength Recovery After Tibialis Posterior Tendon Transfer in Charcot-Marie-Tooth Disease
Key Details
Gender
All
Age Range
18 Years - 55 Years
Study Type
OBSERVATIONAL
Enrollment
100
Start Date
2026-12-01
Completion Date
2035-12-01
Last Updated
2026-10-26
Healthy Volunteers
No
Conditions
Interventions
Tibialis posterior tendon transfer
Tibialis posterior tendon harvest through a medial approach with maximal tendon length preserved; routing through a wide posterolateral window in the interosseous membrane (direct anteriorization) or through the tibialis anterior sheath; insertion into the middle cuneiform or the base of the second metatarsal (or the lateral cuneiform) by bone tunnel or interference/anchor fixation, tensioned with the ankle in neutral dorsiflexion and the forefoot in neutral alignment. The procedure is part of individualized routine surgical care selected by the treating surgeon and is not assigned by the study. Concomitant adjunct procedures and the standardized postoperative rehabilitation protocol are recorded for every participant.
Individualized adjunct procedures for cavovarus deformity correction
Adjunct soft-tissue and bony procedures performed during the same operation at the treating surgeon's discretion, each recorded individually: peroneus longus-to-brevis transfer or tenodesis; flexor digitorum or hallucis longus transfer; Achilles tendon lengthening (percutaneous or open, for resting equinus \> 10 degrees); plantar fascia release; first metatarsal dorsiflexion (closing-wedge) osteotomy; modified Jones procedure (extensor hallucis longus transfer with interphalangeal fusion); lesser claw-toe correction (MTP release, PIP fusion, flexor-to-extensor transfer); cuboid or calcaneal (Dwyer) osteotomy; and midfoot osteotomies. Fixed hindfoot deformity requiring arthrodesis is an exclusion criterion. These procedures are part of routine care and are not assigned by the study.
Ankle-foot orthosis (AFO)
Prescribed ankle-foot orthosis used in routine care before and/or after surgery. Device type, daily wear hours and the percentage of walking episodes with the AFO are recorded at every visit as an exposure of interest and as a secondary outcome (orthosis dependence). The device is prescribed in routine care and is not assigned by the study.