Miller-Peds-Neuromuscular disorders Flashcards
Review Arthrogryposis Syndrome
Overview
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Nonprogressive disorder with multiple joints that are congenitally rigid (Fig. 3.36)
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Can be myopathic, neuropathic, or both
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Associated with a decrease in anterior horn cells and other neural elements of the spinal cord
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Intelligence is normal.
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Evaluation
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Evaluation should include neurologic studies, enzyme tests, and muscle biopsy (at 3–4 months of age).
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Affected patients typically have normal facies, normal intelligence, multiple joint contractures, and no visceral abnormalities.
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Upper extremity involvement
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Adduction and internal rotation of the shoulder
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Extension of the elbow—no appreciable elbow crease
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Flexion and ulnar deviation of the wrist
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Lower extremity involvement
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Teratologic hip dislocations
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Knee contractures (extended is classic, flexed is more common)
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Resistant clubfoot
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Vertical talus
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The spine may be involved, with characteristic C-shaped (neuromuscular) scoliosis (33% of cases).
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Treatment
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Upper extremity
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Passive manipulation and serial casting to achieve some motion
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Posterior elbow release with tricepsplasty to improve motion
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Active elbow flexion achieved through:
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Anterior transfer of long head of triceps or
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Bipolar transfer of latissimus or pectoralis major
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Steindler flexorplasty—transfers origin of flexor pronator to the anterior humerus (rarely indicated because unopposed wrist flexion produces deformity in patients without active extension)
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Osteotomies are also considered after 4 years of age to allow independent eating.
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One upper extremity should be left in extension at the elbow for positioning and perineal care and the other elbow in flexion for feeding.
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Lower extremity
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Hip dislocation
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Unilateral: medial open reduction with possible femoral shortening
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Bilateral: typically left unreduced because ambulation is often preserved
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Pavlik harness contraindicated
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Knee contractures are treated with early (age 6–9 months) soft tissue releases (especially hamstrings).
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Foot deformities (clubfoot and vertical talus) are initially treated with a soft tissue release, but later recurrences may necessitate bone procedures (talectomy).
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The goal is for the foot to be stiff and plantigrade to enable the patient to wear shoes and possibly ambulate.
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Knee contractures should be corrected before hip reduction to maintain the reduction.
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Spine
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Fusion if curve is large (>50 degrees) or progressive
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Large curve magnitude may impede function and ambulatory ability
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Distal arthrogryposis syndrome
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Evaluation
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Autosomal dominant disorder that affects predominantly hands and feet
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Ulnarly deviated fingers (at metacarpal joints), metacarpal and proximal interphalangeal flexion contractures, and adducted thumbs with web space thickening are common.
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Clubfoot and vertical talus deformities are also common.
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Treatment
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Comprehensive releases are more often required, combined with bony surgery.
Review Larson Syndrome
Evaluation
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Similar to arthrogryposis in clinical appearance, but joints are less rigid
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Characterized primarily by multiple joint dislocations (including bilateral congenital knee dislocations), flattened facies, scoliosis, and clubfeet
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Cervical kyphosis (late myelopathy should be watched for) is important to recognize early.
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Affected patients have normal intelligence.
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Autosomal dominant form linked to mutation of gene encoding filamin B
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Autosomal recessive form linked to carbohydrate sulfotransferase 3 deficiency
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Treatment
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Posterior cervical fusion for progressive cervical kyphosis
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Knee reduction may necessitate femoral shortening and excision of collateral ligaments; closed reduction often unsuccessful.
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Open hip reduction is required; closed reduction unsuccessful.
General overview of Spina Bifida
Disorder of incomplete spinal cord closure or rupture of the developing cord secondary to hydrocephalus
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Classification
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Spina bifida occulta: defect in the vertebral arch, with confined cord and meninges
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Meningocele: sac without neural elements protruding through the defect
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Myelomeningocele: in spina bifida, sac with neural elements protrudes through the skin
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Rachischisis: neural elements exposed, with no covering
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Function is related primarily to the level of the defect and the associated congenital abnormalities.
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Myelodysplasia level based on lowest functional level (Table 3.12)
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L4 is a key level because the quadriceps can function and allow household ambulation.
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L5 function is a good prognostic indicator of independent ambulation.
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Evaluation
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Diagnosis
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Can be diagnosed in utero (increased levels of alpha fetoprotein)
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Related to a folate deficiency in utero
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Type II Arnold-Chiari malformation is the most common comorbid condition.
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Central axis
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Sudden changes in function (rapid increase of scoliotic curvature, spasticity, new neurologic deficit, or increase in urinary tract infections) can be associated with tethered cord, hydrocephalus (most common), or syringomyelia.
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Head CT (70% of myelodysplastic patients have hydrocephalus) and myelography or spinal MRI are required.
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Fractures
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Fractures are also common in myelodysplasia, most often about the knee and hip in children 3 to 7 years of age, and can frequently be diagnosed only if redness, warmth, and swelling are noted.
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Fractures are commonly misdiagnosed as infection in these patients.
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Fractures are treated conservatively with well-padded splints.
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Fractures usually heal with abundant callus.
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Treatment principles
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Careful observation of patients with myelodysplasia is important. Several myelodysplasia “milestones” have been developed to assess progress (Table 3.13).
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Treatment involves a team approach (urologist, orthopaedist, neurosurgeon, and developmental pediatrician) to allow maximal function consistent with the myelodysplasia level and other abnormalities.
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Proper use of orthoses is essential in patients with myelodysplasia.
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Determination of ambulation potential is based on the level of the deficit and motivation of the child.
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Surgery for myelodysplasia focuses on balancing of muscles and correction of deformities.
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Increased attention has been focused on latex sensitivity in myelodysplastic patients (immunoglobulin E–mediated allergy).
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A latex-free environment is necessary to prevent life-threatening allergic reactions.
Review the levels of Spina Bifida
Review the lower extremity problems with Spina Bifida
Hip pathology
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Wide spectrum of hip disease
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Flexion contractures
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Hip subluxation and dislocation
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DDH
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Abduction or external rotation contracture
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Management of the hip in patients with myelomeningocele is controversial.
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Flexion contractures
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Occur in patients with thoracic/high lumbar myelomeningocele as a result of unopposed hip flexors or in patients who sit most of the time
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Treatment
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Anterior hip release with tenotomy of the iliopsoas, sartorius, rectus femoris, and tensor fasciae latae
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For patients with lesions at the low lumbar level, the psoas should be preserved for independent ambulation.
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Hip abduction contracture can cause pelvic obliquity and scoliosis; it is treated with proximal division of the tensor fasciae latae and distal iliotibial band release (Ober-Yount procedure).
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Adduction contractures are treated with adductor myotomy
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Hip dislocation
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Caused by paralysis of the hip abductors and extensors with unopposed hip flexors and adductors
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Hip dislocation is most common at the level of L3–4.
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Treatment
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Containment is controversial, but in general, it is considered for low lumbar levels.
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Redislocation may occur no matter what treatment is used to maintain the reduction.
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Principles of treatment should follow those for any paralytic hip dislocation.
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Late dislocation at the low lumbar level may be caused by a tethered cord, which must be released before the hip is reduced.
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The functional outcome of thoracic-level myelomeningocele is independent of whether the hips are in proper position or dislocated.
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Management should focus on limiting soft tissue contractures.
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Knee problems
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Usually include quadriceps weakness (usually treated with knee-ankle-foot orthoses [KAFOs])
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Flexion deformities are not problematic in patients who use wheelchairs but can be treated with hamstring release and posterior capsular release.
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Recurvatum is rarely a problem and can be treated early with serial casting and KAFO.
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Tenotomies (quadriceps lengthening) are sometimes required.
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Valgus deformities are usually not a problem.
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Occasionally, iliotibial band release, guided growth, or osteotomies are needed.
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Ankle and foot deformities
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Objectives: (1) braceable and plantigrade feet and (2) muscle balance
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Calcaneal deformity
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Often caused by unopposed action of the tibialis anterior in patients with paralysis at the lower lumbar level
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Predisposes to heel ulcers that can result in osteomyelitis of the calcaneus
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Passive stretching is initial treatment, but tibialis anterior transfer to calcaneus often required
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At time of transfer, should not be fixed in equinus position, which would predispose to distal tibial metaphyseal fracture.
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Valgus foot and ankle
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Valgus ankle deformity is common in ambulatory patients with the deformity in the distal tibia or subtalar joint (or both).
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Surgical correction is warranted when pressure sores are present and orthotics fail to hold correction.
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For skeletally immature patients: distal tibial hemiepiphysiodesis or Achilles tendon–fibular tenodesis
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For skeletally mature patients: distal tibial osteotomy
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In subtalar region valgus, AFOs are often helpful, but tendon release (anterior tibialis, Achilles), posterior tibialis lengthening, and other procedures may be required.
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Triple arthrodesis should be avoided in most patients with myelodysplasia; it is used only for severe deformities with sensate feet.
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Rigid clubfoot
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Secondary to retained activity or contracture of the tibialis posterior and tibialis anterior; common in patients with L4-level lesions
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Treatment consists of complete subtalar release through a transverse (Cincinnati) incision, lengthening of the tibialis posterior and Achilles tendons, and transfer of the tibialis anterior tendon to the dorsal midfoot.
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Talectomy may be appropriate for refractory clubfoot.
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Spine problems
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Lumbar kyphosis or other congenital malformation of the spine as a result of a lack of segmentation or formation (i.e., hemivertebrae, diastematomyelia, unsegmented bars)
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Treatment of kyphosis is based on problems with skin breakdown or the necessity of using upper extremities to hold up the torso.
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Resection of the kyphosis (kyphectomy) with local fusion or fusion to the pelvis with instrumentation is required in severe cases.
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Scoliosis can also occur with severe lordosis as a result of muscular imbalance that is caused by thoracic-level paraplegia.
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Scoliosis develops in nearly all patients with thoracic-level paraplegia.
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Bracing is generally unsuccessful in treating these spinal deformities.
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Rapid curve progression can be associated with hydrocephalus or a tethered cord, which may manifest as lower extremity spasticity or an increase in urinary tract infections.
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Severe progressive curves necessitate surgical treatment.
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Infection rates are high because of frequent septicemia and poor skin quality over the lumbar spine.
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Pelvic obliquity
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Result of prolonged unilateral hip contractures or scoliosis
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Treatment
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Custom seat cushions, thoracolumbosacral orthosis, spinal fusion, and ultimately pelvic osteotomies may be required.
Review Duchene’s Muscular Dystrophy
Caused by absence of dystrophin protein
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Markedly elevated creatine phosphokinase (CPK) level and absence of dystrophin protein on muscle biopsy and DNA testing
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A muscle biopsy sample shows foci of necrosis and connective tissue infiltration.
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Dystrophin absence leads to poor muscle fiber regeneration and progressive replacement of muscle tissue with fibrofatty tissue.
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X-linked recessive inheritance (Xp21.2 dystrophin gene mutation; one-third of cases are from spontaneous mutation)
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Occurs in young boys
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Physical findings
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Manifests as muscle weakness (proximal groups weaker than distal)
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Clumsy walking
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Decreased motor skills
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Lumbar lordosis
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Calf pseudohypertrophy
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Presence of Gowers sign (patient rises by walking the hands up the legs to compensate for gluteus maximus and quadriceps weakness) (Fig. 3.37)
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Hip extensors are typically the first muscle group affected.
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Also associated with low IQ, megacolon, volvulus, malabsorption
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Treatment
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Goal is to keep patients ambulatory as long as possible.
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Patients lose independent ambulation by age 10 years.
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Although controversial, the use of KAFOs and release of contractures can extend walking ability for 2–3 years.
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Patients are usually wheelchair dependent by age 15 years.
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Patients usually die of cardiorespiratory complications before age 20 years.
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Newer medical treatment includes high-dose steroids, which have been shown to prevent scoliosis formation and prolong walking ability.
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Foot deformities
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Treat with tendo Achilles lengthening (TAL), split posterior tibialis tendon transfer into peroneus brevis (if tibialis posterior active in both stance and swing phase).
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Rancho procedure: TAL, tibialis posterior lengthening, split anterior tibialis transfer into dorsal cuboid
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Scoliosis
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With no muscle support, scoliosis rapidly progresses in virtually all patients by age 14 years.
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Patients can become bedridden by age 16 years as a result of spinal deformity and are unable to sit for more than 8 hours.
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FVC decreases by 4% each year and by another 4% for every 10 degrees of thoracic scoliosis.
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Scoliosis should be treated early (at 20 to 30 degrees of curvature), before pulmonary and cardiac function deteriorate.
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Surgical approach includes posterior spinal fusion with segmental instrumentation to include the pelvis.
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Differential diagnosis
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Becker muscular dystrophy (also sex-linked recessive with a decrease in dystrophin)
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Found in boys with red/green color blindness, with a similar but less severe picture
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Diagnosis of Becker muscular dystrophy applies to patients with the same examination findings but who live beyond 22 years without respiratory support.
Diffence between Becker’s and DMD
Becker muscular dystrophy (also sex-linked recessive with a decrease in dystrophin)
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Found in boys with red/green color blindness, with a similar but less severe picture
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Diagnosis of Becker muscular dystrophy applies to patients with the same examination findings but who live beyond 22 years without respiratory support.
Scoliosis treatment in muscular dystrophy
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With no muscle support, scoliosis rapidly progresses in virtually all patients by age 14 years.
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Patients can become bedridden by age 16 years as a result of spinal deformity and are unable to sit for more than 8 hours.
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FVC decreases by 4% each year and by another 4% for every 10 degrees of thoracic scoliosis.
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Scoliosis should be treated early (at 20 to 30 degrees of curvature), before pulmonary and cardiac function deteriorate.
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Surgical approach includes posterior spinal fusion with segmental instrumentation to include the pelvis.
Fascioscapuluhumeral muscular dystrophy
Causes and findings
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Autosomal dominant disorder typically observed in patients 6 to 20 years of age
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Slow progression of muscle weakness involving muscles of facial expression and proximal upper extremity
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Normal CPK level
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Winging of the scapula
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Inability to whistle
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Treated with stabilization by means of scapulothoracic fusion
WNT DUCT?
Friedrich Ataxia
Autosomal recessive with the frataxin gene
GAA repeat at 9q13
Causes and findings
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Autosomal recessive disorder with problems with the frataxin gene (GAA repeat at 9q13)
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Spinocerebellar degenerative disease with mean onset between 7 and 15 years of age
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Manifests as staggering wide-based gait, nystagmus, cardiomyopathy, a cavus foot, and scoliosis
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Involves motor and sensory defects, with an increase in polyphasic potentials on electromyograms
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Use of a wheelchair is needed by age 15 years; death occurs between ages 40 and 50 years, usually from cardiomyopathy.
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Treatment
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Foot deformities treated with plantar release with or without metatarsal and calcaneal osteotomies early, and triple arthrodesis later
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Spinal fusion when curves progress to 50 degrees; number of levels should be determined as for a neuromuscular curve.
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Bracing ineffective for treatment of scoliosis
Review list of Major Sensory/Heriditary peripheral nerve neuropathies
What is Riley Day syndrome?
Causes and findings
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One of five inherited (autosomal recessive) sensory and autonomic neuropathies
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This disease is found only in patients of Ashkenazi Jewish ancestry.
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Clinical presentation includes dysphagia, alacrima, pneumonia, excessive sweating, postural hypotension, and sensory loss.
Review Charcot Marie Tooth Disease
Charcot-Marie-Tooth disease (peroneal muscular atrophy)
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Causes and findings
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Autosomal dominant sensory motor demyelinating neuropathy
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Two forms are described: a hypertrophic form with onset during the second decade of life, and a neuronal form with onset during the third or fourth decade but with more extensive foot involvement.
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Orthopaedic manifestations include pes cavus, hammer toes with frequent corns and calluses, peroneal weakness, and muscular atrophy usually distal to the knees (“stork legs”).
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Involves motor defects much more than sensory defects
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Low nerve conduction velocities with prolonged distal latencies are noted in peroneal, ulnar, and median nerves.
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Diagnosis is made most reliably by DNA testing for a duplication of a genomic fragment that encompasses the peripheral myelin protein-22 (PMP22) gene on chromosome 17.
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Intrinsic wasting is noted in the hands.
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Most common cause of pes cavus
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The most severely affected muscles are the tibialis anterior, peroneus longus, and peroneus brevis.
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Plantar flexion of the first ray is the foot deformity that occurs first, as a result of a weakened tibialis anterior muscle.
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Treatment for feet
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Plantar release, posterior tibial tendon transfer (if hindfoot varus is flexible); hindfoot flexibility tested via Coleman block test
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The Coleman block test—block placed under lateral rays, allowing first ray to plantar flex (see Fig. 3.20)
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Flexible hindfoot will correct to neutral.
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Rigid hindfoot will not correct to neutral.
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Triple arthrodesis (poor long-term results) versus calcaneal and metatarsal osteotomies (if heel varus is fixed and the foot not too short)
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The Jones procedure for hammer toes, and intrinsic procedures for hand deformity
CMT review orthobullets
Deformity characterized by
cavus (elevated longitudinal arch)
plantarflexion of the 1st ray and forefoot pronation
hindfoot varus
forefoot adduction
Epidemiology
seen in both pediatric and adult populations
67% due to a neurologic condition
when bilateral often hereditary or congenital
Pathophysiology neurologic
diagnosis of neurologic condition is critical to render appropriate treatment
unilateral - rule out tethered spinal cord or spinal cord tumor
bilateral - most commonly Charcot-Marie-Tooth (CMT) disease
muscle imbalances generate deformity
weak tibialis anterior and peroneus brevis overpowered by strong peroneus longus and posterior tibialis
results in plantarflexed 1st ray and forefoot pronation with compensatory hindfoot varus
with the 1st metatarsal plantflexed and forefoot pronated, the medial forefoot strikes ground first
the subtalar joint supinates to bring the lateral forefoot to the ground and maintain three-point contact, resulting in hindfoot varus
while initially flexible, hindfoot varus can become rigid with time
idiopathic
usually subtle and bilateral
traumatic
talus fracture malunion
compartment syndrome
crush injury
Associated conditions conditions which present with cavovarus foot
Charcot-Marie-Tooth disease
Cerebral palsy
Freidreich’s ataxia
Spinal cord lesions
Polio
conditions caused by the presense of cavovarus foot
see complications below
Prognosis depends on
deformity severity
etiology
patient age
Presentation
History
recurrent ankle sprains and lateral ankle pain
peroneal tendon pathology
lateral foot pain
excessive weight bearing by the lateral foot due to deformity
can result in 5th metatarsal stress fractures
painful plantar calluses under 1st metatarsal head and 5th metatarsal head or base
plantar fasciitis
elevated medial arch, forefoot pronation and tight gastronemius lead to contracture of the plantar fascia
Physical exam Coleman block test
evaluates flexibility of hindfoot deformity
technique
place 1” block under the lateral foot
eliminates contribution of the plantarflexed 1st ray and forefoot pronation to the hindfoot deformity
findings
flexible hindfoot will correct to neutral or valgus when block placed under lateral aspect of foot
rigid hindfoot will not correct to neutral
guides surgical treatment
flexible hindfoot deformities resolve with forefoot corrective procedures
rigid hindfoot deformities require corrective hindfoot osteotomy in addition to forefoot procedures
peek-a-boo heel
anterior standing examination shows varus heel “peeking” around the ankle
prominent first metatarsal fat pads
Silfverskiold testcheck dorsiflexion with both knee flexion and knee extension
if tight only with knee extension, then gastrocnemius is tight
if tight also with knee flexion, then soleus is also tight
gastronemius tightness often present with cavovarus foot
altered gait
unstable base of support
increased double limb stance and decreased single limb stance
wasting of 1st dorsal interosseous muscle of the hand
suggestive of CMT
spine exam
scoliosis is suggestive of CMT
spinal dysraphism
Imaging
Radiographs recommended views
standing anteroposterior (AP), lateral radiographs of the ankle
standing AP, lateral and oblique radiographs of the foot
findings AP foot talocalcaneal angle < 20° (nl 20-45°)
hindfoot varus
talonavicular overcoverage
talonavicular angle > 7° indicates forefoot adduction
metatarsal overlap
forefoot pronation
lateral foot lateral talo-first metatarsal angle (Meary’s angle) > 4° apex dorsal
break in Meary’s line caused by plantarflexion of the 1st ray
calcaneal pitch or inclination angle > 30°
sinus tarsi see-through sign and double talar dome sign
due to external rotation of the ankle and hindfoot relative to the xray cassette, which is placed along the medial border of the adducted forefoot
bell-shaped cuboid
increased distance between base of 5th metatarsal and medial cuneiform
oblique foot
metatarsal stress fractures
calcaneonavicular coalitions
Studies
Electrodiagnostic Studies (EMG/NCS) diagnostic algorithm for CMT generally dictates
a neurologic physical exam
electrodiagnostic studies
genetic testing
Genetic studies
used to confirm diagnosis after physical exam and electrodiagnostic studies
Treatment
Nonoperativeaccomodative shoe wearindications
rarely sufficient except in mild deformity
full-length semi-rigid insole orthotic with a depression for the first ray and a lateral wedge indications
mild cavus foot deformity in adult (not indicated in children)
supramalleolar orthosis (SMO) indications
more severe cavovarus deformity recalcitrant to shoewear accomodations
ankle foot orthosis (AFO)indications
may be needed if equinus also present, resulting in equinocavovarus foot deformity
works best if equinus is a dynamic defomrity (not rigid)
lace-up ankle brace and/or high-top shoe or bootsindications
may consider in moderate deformities when patient does not tolerate the more rigid bracing with an SMO or AFO
Operativesoft tissue reconstructionindications
failure of nonoperative treatment
performed with a combination of the following procedures
plantar releaseindications
cavus deformity
technique
plantar fascia release
Steindler stripping (release short flexors off the calcaneus)
peroneus longus to brevis transfer indications
plantar flexed first ray
technique
decreases plantarflexion force on first ray without weakening eversion
posterior tibial tendon transferindications muscle imbalance
posterior tibialis typically is markedly stronger than evertors and maintains strength for a long time in most cavovarus feet
may consider transfer of posterior tibialis to dorsum of foot if severe dorsiflexion weakness of anterior tibialis
lengthening of gastrocnemius or tendoachilles (TAL) indication
true ankle equinus
gastrocnemius recession produces less calf weakness and can be combined with plantar release simultaneously
TAL should be staged several weeks after plantar release
1st metatarsal dorsiflexion osteotomy indications flexible hindfoot varus deformities (normal Coleman block test)
corrects the forefoot pronation driving the hindfoot deformity
lateral ankle ligament reconstruction (e.g. Broström ligament reconstruction) indications
chronic ankle instability due to lignamentous incompetence following long-standing cavovarus
Jones transfer(s) of EHL to neck of 1st MT and lesser toe extensors to 2nd-5th MT necks indication
toe clawing combined with cavus foot
performed if the indication is met and time permits
the modified Jones transfer for the hallux includes an IP joint fusion
lateralizing calcaneal valgus-producing osteotomyindications
rigid hindfoot varus deformity (abnormal Coleman block test)
triple arthrodesisindication
almost never indicated due to very poor long-term results
Complications
Ankle instability
standard lateral ankle ligament reconstruction will fail if cavovarus deformity is not concomitantly addressed
untreated can lead to varus ankle arthritis
Stress fractures
5th metatarsal base (Jones fracture)
4th metatarsal
navicular
medial malleolus
Hallux sesamoiditis
overload from plantarflexed 1st metatarsal head
Peroneal tendon pathology
tendonitis, tears, subluxation or dislocation
peroneus brevis most commonly involved
Plantar fasciitis
contracture of the plantar fascia results from elevated medial arch, forefoot pronation and tight gastronemius
Review myathenenia Gravis
Causes and findings
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Chronic disease with insidious development of easy muscle fatigability after exercise
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Caused by competitive inhibition of acetylcholine receptors at the motor end plate by antibodies produced in the thymus gland
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Treatment consists of cyclosporine, antiacetylcholinesterase agents, or thymectomy.
Review Spinal Muscular Atrophy
Anterior Horn Disorder
Autosomal recessive
loss of survival motor neuron gene
A disease of progressive motor weakness
significant variability in severity of disease
Epidemiology incidence
most common genetic disease resulting in death during childhood
1 in 10,000 live births
location
progressive weakness starts proximally and moves distally
Pathophysiology
caused by progressive loss of alpha-motor neurons in anterior horn of spinal cord
Genetics inheritance
autosomal recessive
mutationsurvival motor neuron (SMN) gene mutation
present in 90% of cases of SMA
a telomeric gene deletion
SMN critical to RNA metabolism and is a mediator of apoptosis
there are two SMN genes
all patients with SMA lack SMN-I protein
severity of disease based on number of functional copies of SMN-II
Associated conditions orthopaedic manifestations of SMA
hip dislocation and subluxation (see below)
scoliosis
lower extremity contractures
Prognosis
see classification
Classification
Type
Name
Presentation
Prognosis
Type IAcute Werdnig-Hoffman disease
• Present at < 6 months
• Absent DTR
• Tongue fasciculationsPoor, usually die by 2 yrs.
Type IIChronic Werdnig-Hoffman disease• Present at 6-12 months
• Muscle weakness worse in LE
• Can sit but cant walkMay live to 5th decade
Type IIIKugelberg-Welander disease• Present at 2-15 years
• Proximal weakness
• Walk as children, wheelchair as adultNormal life expectancy - may need respiratory support
Presentation
Symptoms symmetric progressive weakness that is
more profound in lower-extremity than upper extremity
more profound proximally than distally
Physical examabsent deep tendon reflexes
distinguishes from Duchenne’s muscular dystrophy where DTR are present
fasciculations present
Imaging
Radiographs
scoliosis series
pelvis
Evaluation
Diagnosis based on
DNA analysis
muscle biopsy
prenatal diagnosis is possible
Treatment
Nonoperative
Nusinersen has been FDA approved for treatment of SMA. It is administered intra-thecally.
Operative treat associated orthopaedic disorders (details below)
hip dislocation
scoliosis
lower extremity contractures
Hip Dislocation
Overview
hip subluxation and dislocation occur in 62% with type II SMA, and less frequently in Type III.
Treatment nonoperative observation alone (leave dislocated)indications
standard of care as dislocations typically remain painless and high recurrence rate if open reduction attempted
Scoliosis
Overview
the development of scoliosis is almost universal
usually occurs by age 2 to 3 years
often progressive
Treatment nonoperative bracingindications
devices may delay but not prevent surgery in children younger than ten years
operative PSF with fusion to pelvisindications
progressive curve
technique
address hip contractures and any other lower extremity contractures before PSF to ensure seating balance
to allow for intrathecal Nusinersen to be given after spine surgery, perfrom a laminectomy in the lower lumbar spine that is kept free of fusion. perform fusion of spine around this laminectomy
outcomes
for improved wheelchair sitting
may lead to temporary loss of upper extremity function
Combined PSF with anterior releases/fusion indications
curves >100 degrees
very young child with high risk of crankshaft phenomenon
contraindications
pulmonary compromise
typically not necessary due to the high flexibility of SMA curves
Hip, knee, and ankle contractures
Overview
Common in the hip and knee
Nonambulators also develop ankle equinus
Treatment
Physical therapy
Surgical release is controversial as function in nonwalkers is rarely improved and recurrence is common
