Biomechanical viscoelastic properties in leg muscles of people with hemophilia: a case control study

Abstract

Background

People with hemophilia (PwH) are prone to joint bleeds, resulting in hemophilic arthropathy, potentially altering muscle tissue. Although functional and morphologic impairments are documented, little is known about biomechanical muscle properties in PwH.

Objectives

This study investigates muscle stiffness in relaxed and contracted states in the lower limbs of adult PwH and its relationship to muscle strength and joint health.

Methods

In this cross-sectional case-control study, 40 PwH and 20 healthy controls were assessed. Using myotonometry, stiffness of 8 lower limb muscles was measured under relaxed (S_rel) and maximum voluntarily contracted conditions (S_con). Stiffness increase rate (SIR) was calculated. Joint health was assessed via the Hemophilia Joint Health Score and sonography (Hemophilia Early Arthropathy Detection with Ultrasound), and muscle strength was measured using a mobile isometric force gauge. PwH were stratified by lower limb joint impairment (PwH_minor vs PwH_major).

Results

PwH_major exhibited significantly increased S_rel in anterior thigh and calf muscles compared with controls and PwH_minor (all P ≤ .05, r = 0.397-1.010). Under contraction, PwH_major showed reduced S_con in the tibialis anterior (P ≤ .05, r = 0.511-0.683) and biceps femoris (P = .04, r = 0.390). The SIR was significantly lower in PwH_major across most muscles (all P ≤ .05, r = 0.380-0.573), indicating impaired muscle contractility. Furthermore, muscle strength correlated negatively with S_rel (r_s = –0.220 to –0.430) and positively with both S_con and SIR (r_s = 0.273-0.449). Hemophilia Joint Health Score correlated with myotonometric parameters (r_s = 0.248-0.683), linking joint damage to altered muscle properties.

Conclusion

Advanced hemophilic arthropathy is associated with increased passive stiffness and reduced active muscle response, particularly in stabilizing muscle groups. Myotonometry may serve as a potential supplementary tool for the exploratory assessment of biomechanical muscle status in PwH.