Duchenne muscular dystrophy (DMD) is a progressive, X-linked genetic disorder caused by mutations affecting dystrophin, a protein that stabilises muscle fibres during contraction. It predominantly affects boys, although females can occasionally develop significant manifestations. Without adequate dystrophin, repeated muscle damage leads to degeneration and replacement of muscle tissue by fat and fibrosis. The lower limbs are particularly important because their deterioration affects walking, standing, transfers and independence. Lower-limb problems include progressive weakness, altered gait, contractures, foot deformity, pain and fractures. Understanding how these problems interact is essential for preserving function and quality of life.

Progressive Muscle Weakness

Weakness usually becomes evident in early childhood and initially affects proximal muscles, particularly the pelvic girdle and thighs. Children may struggle to run, jump, climb stairs or rise from the floor. Weakness of the hip extensors and knee extensors makes lifting the body against gravity increasingly difficult. A characteristic finding is Gowers’ sign: the child uses the hands to push against the floor and then “climbs” up the legs to reach standing. This manoeuvre compensates for insufficient proximal muscle strength rather than indicating a primary joint disorder.

The calves often appear enlarged, a feature called pseudohypertrophy. This enlargement largely reflects fatty and connective-tissue replacement and should not be mistaken for increased strength. As weakness progresses, walking becomes slower, falls become more frequent and endurance declines. Eventually, independent ambulation is lost, although timing varies considerably with disease severity and treatment. Glucocorticoids and other specialist-directed therapies can modify progression, making rigid age-based predictions inappropriate. Functional assessment should therefore focus on the individual’s abilities and changing needs.

Gait Abnormalities and Compensation

Lower-limb weakness produces recognisable compensatory gait patterns. Weak hip abductors reduce pelvic stability, contributing to a waddling gait and lateral trunk movement. Weak hip extensors encourage increased lumbar lordosis and altered trunk positioning. These adaptations help maintain balance and reduce the muscular demands of standing and walking, but they also increase energy expenditure and fatigue.

Toe walking commonly develops. Initially, ankle plantarflexion may help position the ground-reaction force anterior to the knee, supporting knee extension when the quadriceps are weak. Consequently, an unusual gait pattern is not always simply a deformity requiring correction; it may be an important compensation. Later, shortening of the calf muscles and Achilles tendon can produce fixed equinus. Reduced foot clearance, difficulty negotiating uneven surfaces and declining balance further increase fall risk. Gait assessment should distinguish flexible compensation from established contracture before treatment decisions are made.

Contractures and Foot Deformities

Contractures are persistent restrictions in joint movement caused by shortening of muscles and surrounding soft tissues. In DMD, they result from muscle imbalance, fibrosis, reduced movement and prolonged positioning. Ankle plantarflexion contractures are particularly common, while hip and knee flexion contractures become increasingly important as mobility declines. Contractures often accelerate after loss of walking because the lower limbs spend more time in flexed positions.

The feet may develop equinovarus, combining a downward-pointing ankle with inward turning of the hindfoot. Progressive deformity can impair shoe fitting, standing, transfers and positioning on wheelchair footplates. Abnormal loading may cause focal pressure, callus and discomfort. After independent walking is lost, maintaining comfortable foot alignment remains valuable for supported standing, skin protection and everyday care. Sensation is generally preserved, unlike in peripheral neuropathy, but limited movement can prevent effective pressure relief. Footwear and orthoses require regular checks for fit and skin irritation.

Bone Fragility, Fractures and Pain

Bone health is another major concern. Reduced weight-bearing and muscle forces diminish the stimulus for bone development, while long-term glucocorticoid treatment can further compromise skeletal strength. Delayed puberty and nutritional difficulties may contribute. Consequently, relatively minor trauma can cause lower-limb fractures, particularly involving the femur. A fracture may have consequences beyond the immediate injury: immobilisation can accelerate weakness and contracture, and a child with marginal walking ability may not recover previous ambulation.

Management requires prompt assessment and a plan that minimises unnecessary immobilisation while respecting fracture stability. Bone surveillance, adequate calcium intake and correction of vitamin D deficiency form part of comprehensive care. Established fragility fractures warrant specialist osteoporosis assessment, with intravenous bisphosphonates considered where indicated. Pain may also arise from muscle fatigue, contractures, poor seating or pressure from footwear. New focal pain should not automatically be attributed to muscular dystrophy, particularly after a fall or transfer incident.

Rehabilitation and Clinical Management

Management aims to preserve function, prevent avoidable secondary complications and maintain comfort, rather than reverse the underlying muscle disorder. Regular physiotherapy assessment should monitor joint range, muscle function, gait, fatigue and transfers. Gentle stretching of vulnerable muscle groups, especially the plantarflexors, hamstrings and hip flexors, is commonly recommended. Night-time ankle–foot orthoses may help maintain ankle positioning, provided they are comfortable and appropriately fitted. Evidence supporting particular contracture interventions is limited, so treatment requires individual review rather than assuming guaranteed benefit.

Submaximal activity, such as supported swimming or appropriately adapted cycling, can encourage participation without excessive loading. High-resistance exercise and strenuous eccentric activity should be avoided because dystrophin-deficient muscle is vulnerable to damage. Rest periods, accessible environments and mobility aids help conserve energy. Rigid daytime ankle bracing can interfere with compensatory walking and should not be prescribed indiscriminately. Supported standing may assist positioning and participation, but requires assessment of contractures, tolerance and fracture risk.

Surgery is reserved for selected situations. Correcting ankle deformity may occasionally benefit a person with sufficient remaining strength or improve positioning after ambulation is lost. However, excessive Achilles tendon lengthening can remove useful compensation and worsen walking. Decisions require coordinated neuromuscular, rehabilitation and orthopaedic input, alongside careful cardiac, respiratory and anaesthetic assessment.

As wheelchair use increases, seating and lower-limb support should accommodate changing posture without forcing painful correction. Caregivers need training in safe transfers and repositioning to reduce injury and pressure damage. Physiotherapists, occupational therapists, orthotists and podiatrists can collaborate on practical solutions. The person’s priorities should guide intervention, balancing potential functional gains against discomfort, treatment burden and disruption to school or family life.

Lower-limb problems in Duchenne muscular dystrophy reflect interacting muscle weakness, compensatory biomechanics, soft-tissue shortening and skeletal fragility. Their effects extend beyond walking to comfort, transfers, participation and independence. Individualised multidisciplinary care can limit secondary complications and support meaningful function throughout changing disease stages.

References

• Apkon, S. D., et al. (2018). Orthopedic and surgical management of the patient with Duchenne muscular dystrophy. Pediatrics, 142(Supplement 2), S82–S89. https://doi.org/10.1542/peds.2018-0333J
• Balachandran, U., Mustapich, T., & Ranade, S. C. (2025). Orthopaedic management in Duchenne muscular dystrophy. Journal of the Pediatric Orthopaedic Society of North America, 10, 100154. https://pmc.ncbi.nlm.nih.gov/articles/PMC12088117/
• Birnkrant, D. J., et al. (2018). Diagnosis and management of Duchenne muscular dystrophy, part 1: Diagnosis, and neuromuscular, rehabilitation, endocrine, and gastrointestinal and nutritional management. The Lancet Neurology, 17(3), 251–267. https://doi.org/10.1016/S1474-4422(18)30024-3
• Birnkrant, D. J., et al. (2018). Diagnosis and management of Duchenne muscular dystrophy, part 2: Respiratory, cardiac, bone health, and orthopaedic management. The Lancet Neurology, 17(4), 347–361. https://doi.org/10.1016/S1474-4422(18)30025-5