How should I evaluate and manage new‑onset groin pain in an older adult after a standard total hip arthroplasty?

Groin Pain After Hip Replacement: Evaluation and Management

Begin with plain radiographs comparing to prior postoperative films to assess for component loosening, osteolysis, or migration, then proceed with an algorithmic approach based on pain characteristics: night/rest pain suggests infection requiring immediate aspiration, while weight-bearing pain indicates mechanical failure. 1, 2

Initial Clinical Assessment

Pain Pattern Characterization

• Night pain or rest pain strongly indicates infection and requires urgent workup, while mechanical pain occurs predominantly with weight-bearing and suggests aseptic loosening or component wear 1, 2, 3
• Groin pain with hip flexion activities, especially ascending stairs or forced flexion, points to iliopsoas tendonitis or impingement 4, 5, 6
• Assess for infection signs: warmth, erythema, fever, or systemic symptoms warrant immediate infection evaluation 3

Physical Examination Findings

• Reproducible pain with resisted hip flexion or provocative iliopsoas maneuvers suggests iliopsoas pathology 5
• Pain with passive range of motion or generalized pain patterns indicate more complex pathology beyond isolated iliopsoas issues 5

Diagnostic Imaging Algorithm

First-Line: Plain Radiographs

• Obtain AP pelvis and lateral hip views comparing to immediate postoperative films 1, 2, 3
• Assess for progressive lucencies >2mm at the bone-prosthesis interface, superior migration of components, osteolysis (expansile well-defined lucent lesions), or periprosthetic fracture 1, 2
• Evaluate trochanteric surface irregularities >2mm indicating abductor tendon abnormalities 2

Infection Workup (if suspected)

• Proceed directly to image-guided hip aspiration for synovial fluid analysis with cell count, differential, culture, and sensitivity—this is the most useful test for confirming or excluding infection 1, 2, 3
• Obtain ESR and CRP (CRP >13.5 mg/L has 73-91% sensitivity, though limited specificity) 3
• If aspiration is positive or highly suspicious, combined WBC scan and sulfur colloid scan provides 88-100% specificity for periprosthetic infection 1, 2, 3

Advanced Imaging Selection

CT with metal artifact reduction is superior for:

• Quantifying osteolysis and assessing bone-implant interface (sensitivity 84.85% vs 33.3-51.5% for radiographs) 2, 3
• Detecting component loosening and evaluating liner wear 3

MRI with metal artifact reduction sequences is superior for:

• Soft tissue evaluation with 95.4% sensitivity for detecting osteolysis 2, 3
• Identifying iliopsoas cysts, tendon tears (12 tendonopathies, 2 tears documented), bursitis, and other soft tissue abnormalities 1, 2, 4
• Detecting lymphadenopathy (93.1% accuracy for infected implants when comparing affected to unaffected hip) 1

Avoid planar bone scans when infection is excluded—insufficient evidence supports their use as they cannot differentiate aseptic loosening from other pain causes 1, 3

Management Based on Diagnosis

Iliopsoas Impingement/Tendonitis

• Measure anterior acetabular component prominence on true lateral radiographs 7
• For prominence <8mm: iliopsoas tenotomy provides 100% groin pain resolution with mean Harris hip score of 89 points 7
• For prominence ≥8mm: acetabular revision achieves 92% groin pain resolution compared to 33% with tenotomy alone 7
• Conservative management resolves groin pain in only 50% of patients 7
• The diagnosis must be correct before proceeding with tenotomy—patients with isolated flexion pain respond best, while those with generalized pain, night pain, or pain with passive motion do not respond favorably 5, 6

Aseptic Loosening or Component Wear

• Orthopedic surgery referral for revision consideration when imaging reveals progressive lucencies, component migration, or significant polyethylene wear leading to osteolysis 2, 3

Infection

• Urgent orthopedic consultation for two-stage revision arthroplasty if infection confirmed 3

Pain Management During Evaluation

• NSAIDs or COX-2 selective inhibitors as first-line analgesics 1
• Paracetamol (acetaminophen) combined with NSAIDs 1
• Avoid long-term opioids; reserve as rescue analgesics only 1, 3

Common Pitfalls to Avoid

• Do not dismiss groin pain as "normal postoperative pain"—up to 18% of patients experience persistent groin pain after hip replacement, with specific treatable causes 6
• Do not rely solely on radiographs—they miss 50-66% of component loosening detected by CT 2
• Do not perform iliopsoas tenotomy without measuring acetabular component prominence—patients with ≥8mm prominence require acetabular revision for optimal outcomes 7
• Do not overlook rare causes like iliopsoas cysts or atraumatic tendon rupture, which require MRI for diagnosis 4, 8