DDH, Muscular Dystrophy and Fractures

Question 1

What is the definition of DDH?

Answer 1

Abnormal growth of hip resulting in instability and dislocation

Question 2

What is the aetiology of DDH?

Answer 2

Multifactorial: IU positioning, gender, ligament laxity, racial

Question 3

What is the epidemiology of DDH?

Answer 3

More comon in first degree relatives, FHx, first born, oligohydramnios, breech delivery, C section, neuromuscular disorders, metatarsus adductus, torticollis.

(metatarsus adductus is like club foot, but it has no hindfoot involvement and therefore the foot is flat, but from the modfoot to frontfoot turned inwards. Ankle straight.)

Question 4

What would you find in the newborn examination in DDH?

Answer 4

· Ortolani: keep one leg in place, rotate the other leg outwards. Rpt other. Relocates hip if + (was dislocated).

· Barlow: Pushing thigh posteriorly. Femoral head dislocates if pushed

Question 5

What is DDH due to?

Answer 5

Due to abnormal acetabular growth, due to absence of a good femoral head. Normal acetabular growth occurs from three ossification centres in the acetabulum, ilium and ischium and occurs in response to positioning of the femoral head on surface. No head = no acetabulum.

Question 6

What are signs of DDH (other than ortolani and barlow)?

Answer 6

low abduction on affected side, bad walking, asymmetry, different leg lencths.

Question 7

What investigations do you do in DDH?

Answer 7

USS hip: reveals relaiton of acetabulum and femoral head and dysplasia. High false + rate.

X ray hip: >4 months, get 4 views in adduction and abduction.

Question 8

What is the management of DDH?

Answer 8

Supportive: pavlik harness abduction splints until 5-6mo. USS monitor.

Surgical correction: late diagnosis >6mo -> preform perioperative traction for 2-3wk and then preform closed reduction (angiography recommended before). Surgical release of adductor longus and iliopsoas may be required. >18 months -> open reduction with osteotomy may be required.

Question 9

What are the complications/ prognosis of DDH?

Answer 9

Iatrogenic: pain and infection from surgery, 5% incidence avascular necrosis with Pavilik harness splinting. Other than this good results in <6/12 kids.

Long term at higher risk of OA of the hip.

Question 10

What is Duchenne’s MD and Beckers MD?

Answer 10

X linked recessive degenerative muscle disorders, characterised by progressive wasting and weakness. DMD is rapid, whereasn BMD is a slow progressing form.

Question 11

What is the aetiology of DMD?

Answer 11

· Gene mutation in Xp21. 2/3 inherited, 1/3 sporadic

· Absence of dystrophin (<5%) -> part of the membrane of the sarcolemma connecting cytoskeleton to basal lamina of muscle.

Question 12

What is the aetiology of BMD?

Answer 12

· Exon deletions in dystrophin gene Xp21.

· Levels are 30-80% of normal, most have some production of partially functional protein.

Question 13

What is the pathology of DMD/BMD?

Answer 13

segmental necrosis of muscle groups. Variation in fibre size, potential regeneration, but when this fails there is replacement with adipose tissue.

Question 14

What is the epidemiology of DMD/ BMD?

Answer 14

DMD in 1/3000 births, BMD in 3/100k births (ALL MALES!)

Question 15

What would you find in the history of DMD and BMD?

Answer 15

DMD: Healthy at birth. At 6 years, progressive weakness, abnormal gait, toe walking, difficulty getting up. By 10, require braces to walk. By 12, wheelchair bound. LD in 20%.

BMD: Symptoms begin at around 10y, milder version than DMD.

Question 16

What would you find in the examination of DMD and BMD?

Answer 16

Weakness distribution: symmetrical, especially in pelvic and shoulder girdle muscles.

Calf muscle pseudohypertrophy: Excess adipose replacement of muscle fibres.

Gower’s sign: Child pushes hands on thigh to overcome weakness

Question 17

What investigations would you do for DMD and BMD?

Answer 17

Bloods: high CK. EMG to exclude neurogenic weakness.

Genetic testing is diagnostic

Muscle biopsy to stain for dystrophin to assess amount.

LFT: low vital capacity, due to low muscle strength.

Question 18

What is the management of DMD/ BMD?

Answer 18

MDT approach

· Medical: oral GCs improve strength, early aggressive management of cardiomyopathy, respiratory assessments, immunisations + pneumococcal and flu. Prophylactic antibiotics if very low VC.

· Orthopaedic: contracture correct, scoliosis repair, scapular fixation.

· OT/PT/education/genetic counselling for CVS/psychological.

Question 19

What are the complications and prognosis of DMD/ BMD?

Answer 19

Loss of mobility, fractures, scoliosis, osteoporosis, respiratory failure, infection, D-CMP.

DMD: respiratory and cardiac failure main COD.

BMD: disease later, most patients walk beyond 16y.

Question 20

What are fractures?

Answer 20

Disruption of continuity and integrity of bone associated with soft tissue injury.

Question 21

What are the aetiologies of fractures?

Answer 21

Direct trauma: when pressure applied on bone exceeds force. Penetrative, crushing, or rotational, compression, tension injury.

Greenstick: incomplete fracture with angulaiton on oppoite side due to stronger periosteum in children.

Pathological when caused by minor force. May be due to malignancy or congenital.

Salter Harris classification: epiphyseal injury involving growth plates. Types I’IV depending on involvement of physis, metaphyis and epiphysis.

Question 22

What is the epidemiology of fractures?

Answer 22

M>F, very common

Question 23

What would you find the history of fractures?

Answer 23

Mechanism of injury, before during and after, when and where, child developmental stages. Also elicit pissibility of contamination, chance of head injury, medications, previous fracture hx.

LOW THRESHOLD FOR SUSPECT NAI.

Question 24

What is in the examination of a fracture?

Answer 24

Closed fracture: pale, swelling, deformity.

Open fracture: bleed, bruise, soft tissue injury over site.

Neurovascular status: assess limb downstream, numb, pulse, paralysis etc.

Musculoskeletal exam: examine joint above and below for crepitus, effusion and pain.

Tuning fork test: exacerbates pain in small stress fractures.

Question 25

What investigations would you use for fractures?

Answer 25

X ray: rule of 2s – 2 views, 2 joints, repeat 7-14/7 later if not apparent.

MIR May be required for ligamentous or soft tissue injury. Bone scan for stress fractures.

Question 26

What is the management of fractures?

Answer 26

Initial: resusc, analgesia, comfort patient, assess other fractures/injuries.

Clsoed reduction: manipulation under anaesthetic.

Open reduciton and internal fixation: adequate exposure before reduction using wires, plates and screws/nails.

External fixation: avoids soft tissues adjacent to fracture.

Immobilisation with plaster casts, tracton by applying tensions realigns fracture for healing. PT may be required in the long term.

Question 27

What are the complications and prognosis of fractures?

Answer 27

Short term neurovascular damate, malunion or non union, infection, thrombotic event, avascualr necrosis.

Medium term compartment syndrome.

Long term may arrest epiphyseal growth if involving growth plate. May lead to arthritis if involving joint.

Typiclaly only require 3-4 weeks UL, 6-8wk LL.