Duchenne Muscular Dystrophy: Orthopedic Concerns

Motor milestones are achieved in a delayed manner, but the majority of children with Duchenne muscular dystrophy (DMD) walk by 18 months of age. By preschool, they exhibit slower motor skills and are less able to keep up with their peers. They may use the Gower's maneuver to get up from the floor and handrails to go up stairs. They also tend to fall more frequently than their peers. Diagnosis of DMD is most commonly made at this stage, and this is when the boys should be referred to an experienced pediatric orthopedic surgeon for evaluation and management of orthopedic complications.

When first diagnosed, a majority of patients have tight heel cords and a history of toe-walking. An orthopedic surgeon experienced in the care of children with DMD should be consulted early on to follow this problem and initiate treatment. This might take the form of heel cord stretching exercises, night splinting, and/or ankle foot orthoses (AFOs).(Although there are no controlled studies that show that any of these interventions prevent contractures.)
At some point, surgery may be necessary to lengthen heel cords, despite other treatments. Some investigators suggest waiting until the fixed deformity is greater than 20 degrees, whereas other investigators suggest doing early prophylactic muscle/tendon lengthening procedures. There are several reasons to proceed with surgery:

• Heel cord lengthening may prolong walking; and
• Preventing foot deformities after wheelchair confinement may help with positioning, and allow continued shoe wearing.

Surgery usually involves performing a tenotomy of the Achilles tendon and the posterior tibial tendon, followed by 4-6 weeks in a cast after which a solid AFO is worn. Some orthopedic surgeons advocate doing a posterior tibial tendon transfer to the dorsum of the foot in order to allow the child to be brace-free after the surgery. As the disease progresses, contractures may also develop at the knees and hips leading to difficulty with wheelchair seating, discomfort while sleeping, and possibly decubiti. Stretching exercises may be useful in delaying these contractures. See Stretches for boys with DMD (Parent Project MD) ( 625 KB). Occasionally, these contractures may also require surgical correction as necessary (e.g.. hip flexor-abductor releases, distal hamstring releases).

• 90-95% of boys with DMD exhibit scoliosis; the age of onset is variable;
• A spine exam and spine X-rays (sitting anteroposterior spine) as necessary should be performed on a routine basis after the age of 10 years or when patients become non-ambulatory;
• The trunk muscles progressively weaken, leading to collapse of the spine into a long C-shaped curve;
• In addition to seating problems and discomfort, scoliosis can lead to respiratory compromise due to decreased lung volume; and
• Scoliosis surgery is recommended when the curvature measures 20 to 30 degrees; bracing is not thought to be helpful and is poorly tolerated.

Surgical Intervention:

• Scoliosis correction is major surgery and needs to be performed before pulmonary function is too compromised, when pulmonary function is no less than 35% of normal;
• The blood loss in this type of surgery tends to be significant and blood transfusions are almost always required;
• Post-operatively, the child will be in the intensive care for several days, with total hospitalization time usually 7 to 10 days; and
• Following correction, the child can sit in the wheelchair more comfortably and for longer periods, and respiratory function is improved.