Paediatric hip diseases

May 9, 2020 0 By FM

The most common hip related complaints with which a child can presentto orthopaedic outpatient departmentare.

1. Painless limping and

2. Painful limping

Groin discomfort (hip pain) can happen because of the lesions in the 

1. Capsule and synovial tissues

2. Pelvic bones

3. Muscles,nerves and vascular structures

Genetic association is shown in Slipped Capital Femoral Epiphysis where 4% of the children have a family history.

Common clinical conditions:

λ Transient Synovitis: The most common cause of hip pain in the day-today practiceoften related with trauma, allergic reactions and recent viral infections and other illnesses.It is otherwise called observation hip where exists a 3% risk for a child to have at least one episode.

λ Legg-Calve-Perthes disease: Peak incidence of this disease happens at the age of 6 yrs. 4 times more in male child than a female and 10% of bilateral incidence. Basically, it is avascular necrosis of femoral head epiphysis.

λ Slipped Capital Femoral Epiphysis (SCFE): It occurs during the period of rapid growth i.e., the adolescent or pre-adolescent period associated withobesity, endocrine abnormalities. It is a progressive disease thatrequires prompt surgical treatment. 

λ Septic Arthritis, including osteomyelitis: Osteomyelitis from upper femoral metaphysis directly extends into the hip joint or haematogenous dissemination of organisms through the blood supply of the synovial tissue can leads to septic arthritis of hip. For the joint aspirate cell count particularly, ultrasoundguided procedure is the most sensitive test;with more than 50,000 cells/mm3. The leukocyte count is elevated. Blood culture is positive in 40% of children. The clinical findings may be misleadingly negative in neonatal age group because of the immature immune system.

  • Juvenilerheumatoid arthritis
  • Bursitis around hip including tuberculosis
  • Leukaemia,lymphoma or sickle cell anaemia
  • Trauma and related conditions
  • Neoplastic and idiopathic conditions

Painless limp conditions include:

  • Developmental dysplasia (DDH)
  • Cerebral palsy
  • Infantile coxa vara
  • Muscular dystrophy
  • Poliomyelitis
  • Limb length discrepancy
  • Perthes disease

Radiology

Transient Synovitis: Plain X-ray AP and lateral views are nonspecific, but they may help to rule out other diagnosis.

Septic Arthritis: Plain radiographs show obliteration of the fat planes and soft tissue swelling. Early osteomyelitis shows mottling of bone density. Later sclerosis develops due to new bone formation. Lytic lesions are due to bony destruction. Very often the end result is the destruction of the femoral head.

Perthes disease: Early feature: Failure of epiphyseal growth and loss of bone density. Later: Crescent-shaped sub-chondral fracture in the femoral head, shortening of the femoral neck, and flattening or enlargement of the femoral head, widening of the growth plate, and mild osteopenia of the proximal femur. (Fig 1)

SCFE: Typical posterior displacement of the capital femoral epiphysis. There is upward and anterior movement of the femoral neckon the capital epiphysis.

Pathological findings:

Septic arthritis: Initially synovial hypertrophy and later cartilage destruction.

Perthes disease: Femoral head flattened and extruded.

SCFE: There is upward and anterior movement of the femoral neckon the capital epiphysis i.e. Posterior and inferior displacement of the femoral head on the metaphysis.

Clinical Scenario 1:

14-year-old obese tall male boy presenting with right hip pain of 1-month duration and limping of 1-month duration. Apparently normal child gives history of insignificant trauma to right hip 1 month ago when he tripped and fell down. Even though he was able to walk after the incident, he had significant pain over the groin which subsided with analgesics over 2 days. There is no rest or night pain, no fever. He is not able to squat. He is the 1st child of a non-consanguineous marriage with no similar complaints in his sibling or parents. General examination findings are within normal limits.

Hip examination:

Inspection: Patient lying supine on a hard couch with hip and knee extended and right lower limb in external rotation. Apparent shortening on the right side noted. Anterior superior iliac spine on the RT side is at a higher level. Thigh muscle atrophied, No scars, sinuses, dilated veins or abnormal swellings anteriorly. Greater trochanter is posteriorly placed and elevated as compared to opposite sidewith no scars or sinuses. Posteriorly no scars, sinuses or swellings or muscle atrophy.

Palpation: No anterior or posterior joint line tenderness.Femoral pulses palpable equally and normally on both sides. Trochanter shows no irregularity, is non tender, smooth, elevated and posteriorly placed. No abnormal masses palpable posteriorly.

Movements:Patient has no fixed flexion deformity, 0 to 120 degrees flexion accompanied by axis deviation evidenced by knee moving to same shoulder past 90 degrees of flexion. Normally knee moves towards the opposite shoulder. Flexion is terminally restricted by pain. Fixed adduction deformity of 10 degrees with free adduction of 20 degrees limited by pain and spasm. External rotation deformity of 30 degree with further ER of 20 degrees limited by pain and spasm. 

Measurements:Patient has an apparent shortening of 2 cm on the right side with true shortening of 1 cm on squaring the pelvis, which is accommodated in the supra trochanteric area on drawing the Bryant’s triangle.No discrepancy of circumferential measurements on both sides. 

No distal neurovascular deficit, no inguinal lymphadenopathy.

Gait: Trendelenburg gait.

Diagnosis: Unilateral hip disease right sided probably due to slipped capital femoral epiphysis (SCFE).

SCFE: A disorder of the proximal femoral physis where a dehiscence occurs through the growth plate of the immature hip. The slip occurs through hypertrophic zone of the physis. Bilateral presentation can occur in 30% of the cases.Most cases are idiopathic. It may be associated with endocrine and metabolic disorders. Imbalance between oestrogen and growth hormone increases the thickness of the physis while reducing its resistance to shear forces,complication of treatment with chemotherapy and radiotherapy, with administration of growth hormone for short stature etc.

Associated Factors include obesity (single greatest risk factor), femoral retroversion and puberty.

Stable slip: The child is able to weight bear with or without crutches.

Unstable slip: Child is unable to tolerate any kind of weight bearing on the affected hip. Unstable hips have a 47% satisfactory prognosis compared to a 96% satisfactory prognosis in the stable-hip group. 

Preslip is a radiographic finding of irregularity, widening and fuzziness of the physis. There may be pain in the hip or knee with minimal limitation of internal rotation of hip.

This condition can give rise to several complications including:

1. Avascular necrosis. Most common complication. Related to unstable (50%) or severe (25%) slip.

2. Chondrolysis – less frequent; 1-2%further slipping after pinning.

Chondrolysis: Rapid progressive loss of articular cartilage associated with pin penetration of the joint and multiple screw fixations. Diagnosis indicated byvirtually no range of hip movement, hip pain and a narrowed joint space. Confirm by MRI.

3. Subtrochanteric fracture. Due to low screw placement at insertion or removal

4. Degenerative joint disease: Can develop in welltreated moderate slips with no complications. Approximately 10% of patients with SCFE develop osteoarthritis.

5. Residual leg length inequality and rotational deformity (severe slips that may require late corrective osteotomy).

Treatment of SCFE:

The aim of treatment is to stabilise the slip to prevent further progression, and to promote physeal closure. 

Operative options include

1. Pinning in situ: with a single cannulated AO screw (for grade I and II slips)

2. Bone graft epiphysiodesis (high complication rates: AVN, chondrolysis, bone formation)

3. Primary osteotomy by experienced paediatric hip surgeon (for severe slip)

In-situ pinning 

A 6- or 7-mm cannulated screw, either partially or fully threaded is inserted into the centre of the epiphysis. Because the epiphysis is posterior, screw insertion begins on the anterior aspect of femoral neck. This is to prevent further slipping and incite closure of physis.

Complications

1. Screw penetration into the joint. To avoid this tip of the screw must be in the centre of the epiphysis both in AP and lateral views. Advance the screw tip to no more than 8mm or one third of the femoral head radius from subchondral bone.

2. Chondrolysis:

Clinically: Pain throughout the arc of motion rather than just at its extremes.The hip is an externally rotated position at rest, with flexion contracture and global restriction of hip motion. 


X-ray:Narrowing of the joint space to at least one-half of that in the contralateral hip in unilateral cases and as narrowing of the joint space to less than 3 mm in bilateral cases.

Scenario 2

A 7-year-old male child has pain right knee and walks with Trendelenburg gait. General health normal. Right limb apparent shortening by 1.5 cms. Abduction limited by 30 degrees and internal rotation by 30 degrees. Trendelenburg sign positive.

X-ray: The bony osteonucleus shrunken, patchy density changes and fragmentation.

Diagnosis: Legg–Calve–Perthes Disease

Discussion:

It is a non-inflammatory idiopathic AVN of the femoral head in a growing child produced by interruption of blood supply to the proximal femoral epiphysis.Aetiology of Perthes disease is poorly understood, there are several theories.Epiphyseal arteries transverse the neck between bone and an inelastic capsule. This makes them vulnerable to pressure rise, e.g. reactive synovitis. The femoral neck venous drainage is disturbed with increased interosseous venous pressure. This leads to arterial or venous thrombosis.There is evidence to support the association between thrombophilic and hypofibrinolytic disorders like protein S and C abnormalities, Leiden factor 5 mutation, anticardiolipin antibodies, micro-trauma or passive smoking etc

It is thought that repeated ischemic episodes at the femoral epiphysis rather than a single event causethe disease syndrome.

Differential diagnosis of unilateral Perthes disease

1. Transient synovitis

2. Infection (septic arthritis, tuberculosis and osteomyelitis)

3. Blood dyscrasias (lymphoma, leukaemia)

4. Juvenile chronic arthritis

5. Rheumatic fever

6. Sickle cell disease

Bilateral in 10 to 12%. Both hips are never at thesame stage of disease (metachronous) unlike in skeletal dysplasia were both hips look similar (synchronous).

Differential diagnosis of bilateral Perthes disease

1. Slipped capital femoral epiphysis

2. Developmental dysplasia of hip

3. Hypothyroidism

4. Multiple epiphyseal dysplasia

5. Spondyloepiphyseal dysplasia

6. Gaucher’s disease

7. Morquio’s disease

8. Trichorhinophalangeal syndrome

Radiological findings

Early radiological findings in Perthes disease aremedial joint space widening (earliest), irregularity of femoral head ossification and crescent sign (represents a subchondral fracture).

The radiographic findings associated with poor prognosis in Perthes diseaseare.

1. Lateral subluxation (most important)

2. Calcification lateral to the epiphysis

3. Gage’s sign: V-shaped defect laterally

4. Diffuse metaphyseal reaction

5. Horizontal growth plate

Bone scan can confirm suspected case of LCP. Decreased uptake (cold lesion) can predate changes on radiographs. MRI can provide early diagnosis revealing alterations in the capital femoral epiphysis and physis.

Treatment

Femoral osteotomy – proximal femoral varus osteotomy to provide containment. It can be combined with de-rotation to reduce anteversion and extension.

Key principles in the treatment of Perthes disease is containment and maintenance of range of motion. Conservative treatment includes NSAIDs, painkillers, physiotherapy and crutches, traction, hospital admission for acute exacerbations and regular outpatient follow-up.

Ambulation abduction brace:This is a difficult type of treatment and there are concerns about when to start and when to finish bracing.

Surgical treatment includes femoral and / or pelvic osteotomy.

Pelvic osteotomy – Salter, triple innominate, Dega or Pemberton osteotomy 

Salvage procedures includesShelf arthroplasty. Indicated in the older child to prevent subluxation and increase acetabular coverage. Chiari osteotomyperformed in the older child with little remodelling potential to increase the load-bearing area may buy several years of painfree hip function before further surgery is required.If the child presenting with hinged abduction, Valgus osteotomy, may be benefited when an enlarged head is laterally extruded and impinges against the lateral acetabular rim on abduction, causing pain.

Epiphysiodesis of the greater trochanter: To prevent trochanteric overgrowth.

Why is the greater trochanter thickened in Perthes disease?

1. Lateral subluxation

2. Muscle wasting and adduction deformity making palpation easier

3. Coxa vara making the greater trochanter more prominent

4. Overgrowth off greater trochanter as its growth is unaffected and because of increased pull of abductors on the greater trochanter in coxa vara.

End result of the disease

  1. Loss of shape of femoral head
  2. Collapse of femoral head
  3. Leg length discrepancy
  4. Loss of range of motion and contractures of muscles
  5. Early degenerative joint disease
  6. Recurrent painful hip syndromes because of mechanical synovitis and failed abductor mechanism
  7. Almost 50% of children affected with Perthes disease may develop arthritic in their 50s. Children who develop Perthes disease by 6 years of age have a better prognosis than those who develop by 8 years of age group.

Importance of surgical treatment

Surgery may be helpful in increasing the containment of the femoral head. By making use of biological plasticity movement with containment can
prevent or lessen thelater arthritic changes that can happen in the femoral,head and acetabulum.

The child and parents should know the following important points:

  1. Maintaining range of motion is important in the treatment protocol.
  2. The femoral head may take 1.5 to 2 years to heal.
  3. After healing very often child may be pain free, but problems may develop later in adulthood.
  4. No 100% effective means of prevention exists, and we cannot accelerate the healing process by doing surgery.
  5. Early detection of the condition is very important, so that surgical containment can be achieved before deformity of femoral head occurs.

The end result of a naturally progressed Perthesdisease is shown below in Fig 9. We are giving prompt surgical treatment is to prevent the complications that can happen in long run. Fig 9: Shows the complication that had happened in an untreated Perthes disease where the femoral head is flattened, trochanter was overgrown and osteoarthritic changes had happened. This patient could not walk and could not do daily activities.

In such a type of scenario the choice of treatment is total replacement arthroplasty (Fig 10). But if the person is below 4o years and if he is a manual labourer he cannot continue with the job and eventually he has to modify his job. In such condition arthrodesis that means surgical fusion of the joint is the management of choice.