Differentials
Hip fractures
SIGNS / SYMPTOMS
History of significant trauma.
INVESTIGATIONS
X-ray shows increased soft tissue shadow and displacement of the epiphysis in any direction.
Avascular necrosis
SIGNS / SYMPTOMS
Age of onset typically seen at 30 to 50 years.
Features of underlying disorder may be present (e.g., systemic lupus erythematosus, Cushing's disease).
Can result from slipped capital femoral epiphysis in its own right.
INVESTIGATIONS
In initial stages, MRI may show decreased intensity for both T1- and T2-weighted images.
Legg-Calve-Perthes' disease
SIGNS / SYMPTOMS
Clinical features often similar to slipped capital femoral epiphysis (e.g., onset of pain, limp, restricted range of motion).
Age range is typically <10 years old.
INVESTIGATIONS
Plain x-rays may show sclerosis, cysts, or collapse of the femoral head.
MRI shows high signal intensity on T2-weighted images and low signal intensity on T1-weighted images in the subchondral region.
Hip dysplasia
SIGNS / SYMPTOMS
May range from mild, asymptomatic cases to severe dysplasia with congenital hip dislocation.
Moderate-to-severe dysplasia may predispose to early osteoarthritis, labral tear, or impingement, and present with findings secondary to one or more of these conditions.
Patients with dislocation often have shortening of the involved leg and decreased hip abduction.
INVESTIGATIONS
Shallow, more vertically oriented acetabulum seen on plain films.
Subluxation/dislocation of the femoral capital epiphysis from the acetabulum.
Osteomyelitis
SIGNS / SYMPTOMS
Typically chronic or acute-on-chronic presentation with vague pain complaints.
May have at-rest or night pain.
Constitutional symptoms (fevers, chills, malaise) often present.
Unremarkable hip examination possible if infectious process involves pelvis.
INVESTIGATIONS
Elevated WBC, CRP, and ESR.
Blood cultures may be positive for infective organism.
Plain film x-rays may show changes consistent with chronic osteomyelitis in some cases.
MRI associated with higher sensitivity and specificity in select patients.
MRI shows increased signal intensity on T2-weighted images and intra-osseous/sub-periosteal abscess.
Septic arthritis
SIGNS / SYMPTOMS
Severe pain with weight-bearing activities.
May be accompanied by fevers, chills, and malaise.
Resting position of hip flexion, abduction, and external rotation to relieve pain.
Pain with passive range of motion on examination.
INVESTIGATIONS
Plain x-rays may show increased joint space.
Joint effusion seen on ultrasound.
Joint aspiration for synovial fluid analysis and culture may yield positive culture.
Groin pain/pull
SIGNS / SYMPTOMS
Pain on adduction, direct tenderness in groin.
INVESTIGATIONS
Tenderness directly over the groin and adductor tendons; no external rotation deformity.
Ankylosing spondylitis
SIGNS / SYMPTOMS
Spondyloarthropathy typically seen in young-to-middle-aged men.
Hip joint involvement is common, often bilateral.
Symptoms (stiffness, pain) are worse in the morning and improve during the course of the day.
Low back and sacroiliac joints are also frequently affected.
INVESTIGATIONS
Plain film x-rays of the hip and pelvis may demonstrate irregularities of the sacroiliac joints with erosive/sclerotic changes.
Classic bamboo-spine appearance seen on spinal x-ray.
Stress fractures
SIGNS / SYMPTOMS
History may indicate overuse injury (e.g., endurance athlete or military recruit).
INVESTIGATIONS
X-rays show oedema or stress reaction in the region of the femoral neck.
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