Guidelines for Evaluation and Management of Monoarticular Hip Pain

Emergency Diagnosis

Septic arthritis is the most common cause of acute severe monoarticular hip pain in children and constitutes a medical emergency at any age; prompt diagnosis and treatment are required to prevent permanent joint damage. – American College of Radiology recommendation 1
Staphylococcus aureus spread through the bloodstream is the predominant pathogen in septic hip arthritis, with the hip being the most frequent joint involved. – American College of Radiology 1
Fever, erythema, warmth, or any sign of infection mandates immediate arthrocentesis; antibiotics must not be given before joint aspiration. – American College of Radiology 1

Fracture (including occult and stress types) must be excluded in elderly, diabetic, or osteoporotic individuals presenting with focal bone pain or recent trauma. – Orthopedic Society guideline (Praxis) 2
Osteonecrosis should be suspected in diabetic patients with insidious hip/groin pain without a traumatic event; key risk factors include diabetes, systemic corticosteroid use, excessive alcohol intake, and sickle‑cell disease. Early detection is essential because progression leads to femoral‑head collapse. – Orthopedic Society guideline (Praxis) 2
Obesity and advancing age are major risk factors for primary osteoarthritis, which typically causes anterior hip/groin pain that worsens with activity. Physical examination and plain radiography provide reasonable sensitivity and specificity for diagnosis. – American College of Radiology 3
Assess for spine or pelvis pathology when hip pain may be referred; a thorough history and physical exam should include evaluation for dermatomal sensory loss and gait abnormalities. – British Society of Sports Medicine 5

Anteroposterior pelvis and lateral femoral‑head/neck views (frog‑leg, Dunn, or cross‑table) are mandatory initial studies for all patients with hip pain. – American College of Radiology 3
Radiographs can reveal joint‑space narrowing, cam/pincer morphology, femoral‑head collapse, acetabular dysplasia, fractures, and neoplastic lesions; they serve as an excellent screening tool and should be obtained in most cases. – American College of Radiology 3

MRI of the hip without contrast is superior for detecting osteonecrosis, occult fractures, bone‑marrow edema, and soft‑tissue pathology; it should be the next imaging step after plain films for the majority of conditions. – American College of Radiology 3
In diabetic patients, MRI is especially important to identify early osteonecrotic changes. – Orthopedic Society guideline (Praxis) 2

When clinical suspicion for a labral tear or femoroacetabular impingement (FAI) is high, MR arthrography is indicated; it outperforms conventional MRI for visualizing labral pathology and cartilage delamination. – American College of Radiology 6

Ultrasound provides rapid detection of joint effusion and can guide aspiration procedures. It also evaluates peri‑articular structures such as the trochanteric bursa, abductor tendons, and snapping hip. However, it cannot adequately visualize intra‑articular cartilage or the acetabulum. – American College of Radiology 1, 3, 7

For suspected L3 radiculopathy (characterized by medial lower‑leg sensory loss and buttock/lateral‑hip pain with negative hip‑specific tests), lumbar spine MRI without contrast is the first‑line study to assess disc herniation or foraminal stenosis. – Orthopedic Society guideline (Praxis) 9

Image‑guided intra‑articular hip injection with anesthetic ± corticosteroid offers both diagnostic confirmation (pain relief indicates intra‑articular source) and therapeutic benefit. – American College of Radiology 3
Targeted trochanteric or iliopsoas bursal injections help localize peri‑articular pain sources. – American College of Radiology 3

Femoroacetabular impingement (FAI) syndrome affects young to middle‑aged active adults, producing anterior hip/groin pain; it is frequently associated with labral tears and cartilage damage. Diagnosis requires both clinical findings and imaging; imaging alone is insufficient. – British Society of Sports Medicine 4
Labral tears present with anterior hip/groin pain and mechanical symptoms such as clicking, catching, or locking; they often coexist with FAI. – American College of Radiology 6
Acetabular dysplasia or hip instability can cause hip‑related pain in younger adults; assessment of bony morphology on imaging is essential. – British Society of Sports Medicine 4

Greater trochanteric pain syndrome (GTPS) is characterized by lateral hip pain and includes trochanteric bursitis and abductor tendon pathology (gluteus medius/minimus tears). A Trendelenburg gait pattern suggests an abductor tendon tear. – American College of Radiology 3

L3 radiculopathy produces dermatomal sensory loss along the medial lower leg and pain radiating to the buttock, lateral hip, and anterior‑lateral thigh; negative hip‑specific maneuvers (FABER, FADIR) effectively exclude intra‑articular hip disease. – Orthopedic Society guideline (Praxis) 9

Never rely solely on imaging to diagnose hip pain; clinical signs and patient symptoms must be integrated. – British Society of Sports Medicine 4
Incidental imaging findings are common in asymptomatic individuals; management should be guided by clinical correlation. – British Society of Sports Medicine 5
Multiple hip conditions may coexist (e.g., labral tear with FAI); comprehensive assessment is required. – Orthopedic Society guideline (Praxis) 8
The straight‑leg‑raise test is insensitive for detecting upper lumbar (L3) radiculopathy. – Orthopedic Society guideline (Praxis) 9
Clinical examination tests for hip pathology have limited sensitivity and specificity; use them as part of a broader diagnostic algorithm. – British Society of Sports Medicine 5