Management of Right Hip Pain After Right Total Knee Replacement

Initial Diagnostic Approach

The American College of Radiology recommends beginning with plain radiographs of the right hip as the first-line imaging study to assess for component loosening, wear, osteolysis, or periprosthetic fracture, followed by targeted advanced imaging based on initial findings 1, 2
Characterize the pain pattern carefully: Night pain or pain at rest strongly suggests infection, while pain predominantly on weight-bearing indicates mechanical issues such as aseptic loosening or component wear 1, 3, 4
Assess for infection signs: Warmth, erythema, fever, or systemic symptoms warrant immediate infection workup, as periprosthetic joint infection is the most serious complication requiring urgent management 5

Obtain comparison radiographs of the right hip to evaluate for component migration, progressive lucencies, osteolysis, or periprosthetic fracture 1, 2, 6
Key radiographic findings to assess: Component position, presence of lucencies >2mm, progressive osteolysis, heterotopic ossification, or greater trochanter abnormalities suggesting abductor tendon pathology 7

If infection is suspected, proceed directly to image-guided hip aspiration for synovial fluid analysis with cell count, differential, culture, and sensitivity—this remains the most useful test for confirming or excluding infection 6, 5
Laboratory markers: Obtain ESR and CRP, though these have limited specificity; CRP >13.5 mg/L has 73-91% sensitivity for infection 4
If aspiration is positive or highly suspicious: Combined WBC scan and sulfur colloid scan has high specificity (88-100%) for periprosthetic hip infection 2

CT advantages: Superior for quantifying osteolysis, assessing bone-implant interface, detecting liner wear, and evaluating component loosening with metal artifact reduction algorithms 1, 2
MRI advantages: Better for soft tissue evaluation (sensitivity 95.4% vs 74.7% for CT in detecting osteolysis), can identify 21 soft tissue abnormalities including tendon tears and bursitis that SPECT/CT misses 1, 2
Avoid planar bone scans: Insufficient evidence supports their use when infection is excluded, as they cannot differentiate aseptic loosening from other causes of pain 1, 2

If imaging reveals aseptic loosening or significant wear: Orthopedic surgery referral for revision consideration is appropriate 6
If imaging is negative but pain persists: Bone SPECT/CT should be considered to identify alternative pain sources including spine pathology 1, 2
Multimodal pain management: NSAIDs as first-line, avoid long-term opioids, and consider physical therapy focusing on core strengthening and hip stabilization 3