Fortunately, pain following THA is a rare. However, over the lifetime of a THA, patients can experience discomfort. Causes of a painful THA are either intrinsic or extrinsic. Intrinsic etiologies originate from the hip joint itself, while extrinsic causes originate from the soft tissues around the hip.

Intrinsic Causes

Three etiologies – periprosthetic joint infection, periprosthetic fractures, and joint instability (subluxation and dislocation) – likely represent the most common causes of a painful THA.

Rarer etiologies for painful THA include hematoma/seroma, component loosening, and component failure (such as polyethylene wear over time, catastrophic polyethylene failure, liner dislocation, fracture of older ceramic heads, and implant fracture).

More recently, metal particle-associated etiologies, such as trunnionosis and adverse local tissue reactions (ALTR) due to the use of metal-on-metal bearings, have been described. There can also be prosthesis-related thigh pain of an otherwise well-ingrown and unremarkable implant.

Extrinsic Causes

The most common extrinsic etiologies for painful THA include lumbar radiculopathy, bursitis (such as trochanteric bursitis), and tendinitis (such as hip abductor/abductor tendinitis and iliopsoas tendinitis).

Much rarer extrinsic causes of painful THA, such as peripheral vascular disease and pelvic insufficiency fractures, should also be considered. In addition, pain related to intra-abdominal or retroperitoneal pathologies – such as inguinal hernias, genito-urethral pathologies, colorectal pathologies, or abdominal aortic aneurysms – can radiate into the groin region. Soft tissue trauma with hip contusion should be considered as well.

Table 1 summarizes the potential causes of painful THA.

Table 1. Intrinsic and Extrinsic Causes of Painful Total Hip Arthroplasty

ICJR: How do you work up the patient who presents with pain to determine its cause? 

Scott M. Sporer, MD: The workup of a painful THA should follow a stepwise and logical approach.

Obtain a thorough medical and surgical history.

• When and where was the surgery done? Which components were used? Obtain the operative report, if possible.
• Were there any perioperative complications, such as dislocations, repeat surgeries, washouts, or prolonged antibiotic intake?
• Where is the pain located? Are there any aggravating or alleviating factors? Is the pain constant or transient? Is the pain identical to or different from the preoperative pain?

Perform a thorough physical examination.

• A careful assessment of gait pattern should be done. Any antalgic gait or limp? Any leg-length discrepancy? Does the patient use an assistive device for walking?
• Prior surgical wounds should be judiciously inspected and examined. Is the incision well healed? Any surrounding erythema, cellulitis, or draining sinus? Any palpable subcutaneous fluid collection? Any surrounding ecchymosis?
• Assess the hip range of motion. Does the patient experience any pain or subjective instability? What is the overall range of motion?
• Palpate the periarticular structures. Does the patient experience any pain in the greater trochanteric region, hip abductors, or groin? Special tests, including straight leg raise, resisted straight leg raise, and resisted hip flexion in sitting position, as well as a detailed distal vascular and neurologic examination, should be performed if pain can’t be reproduced with the clinical exam.

Evaluate radiographs, including preoperative and immediate postoperative radiographs from the index procedure.

• Any periprosthetic fractures?
• Any change in component position compared with prior radiographs? Are components ingrown? Is component position adequate? Any eccentric position of femoral head and acetabular component? Any signs of osteolysis?
• Were hip biomechanics restored pre- to postoperatively?
• Does the patient have metal-on metal articulations or any recalled THA implants?

Order and evaluate special tests as needed.

• Blood testing can be performed to screen for periprosthetic joint infection, including the serum erythrocyte sedimentation rate (ESR) and the serum C-reactive protein (CRP) level. Novel biomarkers for periprosthetic joint infection have recently been introduced, such as neutrophil elastase, alpha-defensin, and synovial fluid CRP.
• Metal particle-associated etiologies can be assessed by obtaining serum cobalt and serum chromium levels.
• A CT scan or MARS-MRI can be helpful in further assessing component positioning when working up instability.

In general, any painful THA should be considered infected until proven otherwise. Screening should entail serum ESR and CRP, and if either (or both) is elevated, or if there is substantial clinical suspicion, joint aspiration with assessment of synovial white blood cell count and neutrophil percentage should be performed.

Periprosthetic fractures or frank dislocations are often relatively easy to diagnose radiographically. Other above-described intrinsic causes of painful THA should be ruled out with a combination of thorough history taking, examination, careful radiographic analysis, and, if warranted, additional laboratory workup.

Once intrinsic causes of painful THA are excluded, extrinsic etiologies should be considered. Most extrinsic etiologies can be evaluated using a combination of thorough physical examination and radiographic analysis. Rare extrinsic etiologies, such as intra-abdominal or retroperitoneal processes or peripheral vascular disease, may require referral to a specialist.