Total hip arthroplasty (THA) is one of the most successful procedures in orthopedics, demonstrating excellent survivorship and low complication rates in the treatment of degenerative hip disease [1]. Pain relief remains the primary goal of THA, yet many patients continue to experience persistent pain postoperatively, even in the setting of well-fixed and acceptably aligned components. Prior reports have noted up to 40% of patients to report some pain following their THA, and thus persistent pain following THA remains a concern [2–10]. In a prospective investigation of 196 patients less than 60 years of age undergoing THA, Nam et al. found 40% of patients report pain in at least one location around the hip, with 29% reporting groin pain, 25% reporting anterior thigh pain, and 20% reporting lateral thigh pain when assessed using a pain-drawing questionnaire [11]. Trochanteric pain was noted to be very high, with 37% of THA patients reporting pain in that location.

As groin pain is often a presenting symptom in patients seeking THA, its presence postoperatively remains a major concern for patients. Potential causes of groin pain following THA include impingement of the femoral neck against the acetabulum or soft tissues, irritation of the iliopsoas tendon across the rim of the acetabular component, or potential anterior instability with irritation of the capsule and anterior musculature [3, 12]. Furthermore, numerous factors have been associated with the occurrence of thigh pain after the use of cementless femoral stem fixation in THA including a patient’s bone quality, prosthesis design, stem size, age, gender, and activity level [13–15].

Given the high prevalence of pain following THA, patient education remains critical. Surgeons must counsel their patients prior to THA that even in the setting of well-fixed and acceptably aligned components, there remains the risk that some symptoms may persist. Mancuso et al., in a telephone interview of 405 patients undergoing THA, noted that only 43% of patients reported all of their preoperative expectations to have been fulfilled following THA [8]. In addition, prior reports have noted failure to fulfill patient preoperative expectations as the primary predictive factor of patient dissatisfaction following total joint arthroplasty [16, 17].

However, while patients may present with a painful THA without a clear etiology, it is critical that the physician is aware of the wide array of identifiable causes of pain following THA that require investigation. Potential etiologies include infection, component loosening, fracture, soft-tissue impingement, bursitis, tendonitis, bearing surface wear, and synovitis as well as adverse local tissue reactions secondary to corrosion at modular junctions [12, 18]. Ulrich et al. reviewed 225 revision THAs performed over a 6-year time period at two centers, and noted 51.9% to be revised for aseptic loosening, 16.9% for instability, and 5.5% for infection. The most common causes for revision within 5 years were instability and infection [19]. Haynes et al., in an institutional review of 870 revision THA procedures, noted the most common indications for revision surgery to be aseptic loosening (31.3%), osteolysis (21.8%), and instability (21.4%) [20]. The introduction of highly cross-linked polyethylene in total hip arthroplasty has demonstrated excellent wear properties; thus revision specifically for periprosthetic osteolysis will hopefully decrease and implant longevity will improve [21, 22]. However, osteolysis still remains a predominant cause of long-term failure, especially in THAs implanted prior to the introduction of highly cross-linked polyethylene and in malpositioned components predisposed to eccentric loading. Thus, there are an extensive number of potential etiologies of pain following primary THA, and it is critical that physicians maintain a systematic approach towards the painful THA to avoid a missed diagnosis. The purpose of this chapter is to review the evaluation and approach to the painful THA, including the physical examination, radiographic analysis, and indications for secondary imaging and laboratory studies that may guide the physician towards a diagnosis.

A thoughtful, precise history is tremendously valuable in the evaluation of the patient with a painful THA. Being thorough can narrow the differential diagnosis and focus the diagnostic workup considerably. It is helpful to categorize pain arising from THA into intrinsic origins and extrinsic origins (Table 7.1), and attention should be directed towards the location of pain, time of onset, severity, character of the pain, precipitating factors, and relieving elements.

In a patient presenting with a painful THA, it is often beneficial to obtain the patient’s prior clinical and operative records, along with implant stickers identifying the specific prosthesis utilized. This can provide valuable insight into potential intraoperative or perioperative complications that may have occurred and provide clues towards etiologies of the patient’s pain. In addition, implant records allow the surgeon to keep in mind specific failure mechanisms that are associated with certain devices, and they are also useful during preoperative planning of a revision procedure.

The temporal onset in particular can provide a wealth of clues. If the patient has had pain since the index procedure without a pain-free interval, then failed fixation of implants, acute infection, intraoperative or postoperative fracture, or misdiagnosis of the patient’s original disability (lumbar spine disease) are all potential causes [23–25]. Likewise, delayed pain years after the well-functioning index arthroplasty is performed is suggestive of aseptic loosening; while osteolysis, chronic infection, and periprosthetic stress fracture are also included in the differential. While a history of multiple dislocations regardless of the time of presentation presents a clear diagnosis as a potential etiology of pain, more subtle findings such as hip instability and increased demand on secondary stabilizers of the hip joint may require further investigation.

The location can also provide the physician with insight into the etiology of pain. Groin or buttock pain often indicates acetabular component (loosening, uncoverage of component, osteolysis), capsular, or iliopsoas dysfunction (tendinitis or impingement). Acetabular component uncoverage of >5 mm on a cross-table lateral radiograph has been associated with an increased likelihood of groin pain following THA [8]. Furthermore, in a patient with eccentric polyethylene wear, corrosion at a modular interface, or metal-on-metal bearing surface wear, intra-articular debris may stimulate an inflammatory response leading to synovitis and groin pain [26]. Less likely origins of groin pain also include hernias , metastatic cancer, neuropathy, vascular pathology, retroperitoneal abscess, and certain metabolic conditions (Paget’s disease) [27–30].

In contrast, anterior thigh pain is often related to the femoral component, and can represent loosening or an elastic modulus mismatch between an uncemented stem and bone in the case of end-of-stem pain [5, 31–34]. With the use of cementless femoral fixation, it is hypothesized that a more physiologic stress transfer with loading of the proximal, metaphyseal femur should diminish the incidence of thigh pain, while isolated loading of the diaphyseal region may increase its incidence. However, multiple factors may predispose a patient to postoperative thigh pain including the femoral stem design used, stem composition (titanium vs. cobalt-chrome), and native femoral anatomy [15, 33, 35]. Cooper et al., in a retrospective review of 320 consecutive THAs performed using a proximally coated, tapered wedge femoral stem, found a greater canal fill at the distal-third of the femoral stem to be a risk factor for failed stem osseointegration and pain [15].

One specific symptom often described is “start-up” pain, or pain at the initiation of activity (often walking) that subsides with increased movement. This symptom is often indicative of femoral stem loosening or failure of ingrowth [36]. This is in contrast to “end-of-stem pain ” as described by Engh and Bobyn, in which micromotion at the tip of the femoral stem (often in an implant well fixed proximally) or load transmission through the tip of the stem to the native femur may cause discomfort [34]. Of note, in a well-fixed cemented femoral prosthesis, thigh pain is rare as bone cement distributes the load over the full length of the stem and prevents apical oscillations seen with end-of-stem pain [37]. Thus, thigh pain in a patient with a cemented femoral prosthesis is often indicative of component loosening [38].

Pain localized over the greater trochanter is very common following THA and often represents bursitis. However, it can also be attributed to abductor deficiency or fracture of the greater trochanter from trauma and/or osteolysis [11, 39]. Thus, a thorough clinical examination is essential to distinguish bursitis from abductor deficiency or potential periprosthetic fracture.

Pain that becomes more severe with activity, such as walking or standing, and is significantly improved with rest, suggests loosening, fracture, or vascular/neurogenic claudication. Alternatively, rest pain that is constant or night pain should raise one’s suspicion for deep infection or tumor. The surgeon should also inquire about postoperative wound drainage, fever, or being prescribed a course of oral antibiotics if an infectious cause for THA pain is being sought. As noted earlier, significant pain that occurs with the first few steps the patient takes and then improves (“start-up pain ”) can occur with a loose or fibrous adherence of a cementless femoral component, but may also be present due to inadequate acetabular component fixation.

Precipitating and relieving factors should also be identified during the patient interview. Pain occurring after a fall or other traumatic event could be the result of fracture or component subluxation/dislocation. The patient that has a painful THA after a urologic, gynecologic, or gastrointestinal surgery, systemic illness, or dental procedure should be worked up for infectious etiology. Additionally, radiating hip pain or numbness that has improved with physical therapy, oral steroids, or epidural injections could be attributed to lumbar disc disease, a frequently missed diagnosis in these patients [23, 25, 40].

A comprehensive examination of the patient presenting with a painful THA includes evaluation of the hips, knees, and spine. Neurogenic and vascular causes of pain should be ruled out. A detailed neurovascular examination including deep tendon reflexes, sensory assessment, and peripheral pulses can often distinguish lumbar spine and vasculogenic pain from true hip pain. The patient’s gait should be scrutinized for a Trendelenburg gait, antalgia, limb-length inequality, and muscular deficiencies. A Trendelenburg gait often suggests abductor weakness whereas an antalgic gait can be secondary to numerous hip or spinal conditions. True limb lengths can be determined with wooden blocks and are differentiated from apparent limb lengths caused by abduction or adduction contractures, scoliosis of the lumbar spine , or fixed pelvic obliquity. Plaas et al. reported on limb-length discrepancy in THA in regard to function and pain [41]. They found that limping was more common in patients with a shorter postoperative leg while pain was more common in patients with a longer operative leg when compared to patients with equal leg lengths (within 3 mm) [41].

The skin of the back and lower limbs is assessed for signs of infection (warmth, drainage, fluctuance), open wounds, tender bursae (especially over the greater trochanters), or hernias. Additionally, hip and knee arc of motion can provide valuable information, especially when symptoms can be reproduced, for narrowing the differential. Pain with passive motion can be the result of infection, fracture, synovitis, or gross component loosening. On the other hand, pain with active or extreme motion may indicate loosening, instability, or impingement. Pain from iliopsoas tendonitis can be elicited with resisted hip flexion or passive extension, while pain with ipsilateral or contralateral passive straight leg raise is often noted in lumbar spine disease. If based on the physical examination multiple potential etiologies of pain are identified, local anesthetic injections may prove both diagnostic and therapeutic. Ultrasound-guided injections into the iliopsoas sheath are often useful in identifying iliopsoas tendonitis, while trochanteric bursa or lumbosacral injections may also help to localize a patient’s symptoms. Pain due to hip instability or subluxation may be elicited with provocative maneuvers such as hip flexion, adduction, and internal rotation (posterior instability), or extension and external rotation (anterior instability), although significant caution should be used to avoid frank dislocation in the outpatient clinical setting.

Lastly, prior to performing the physical examination in a patient with a prior total hip arthroplasty, the authors suggest that standard anteroposterior pelvis and lateral hip radiographs are obtained and reviewed. In the setting of gross implant loosening, instability, or fracture, the physical examination should be limited to avoid worsening of a patient’s condition (Fig. 7.2).

All patients presenting with a painful primary total hip arthroplasty should receive radiographic imaging as part of their initial evaluation. Plain radiographs, including an anteroposterior pelvis and cross-table lateral radiograph of the entire prosthesis, can prove tremendously useful in narrowing the differential diagnosis. Radiographs may clearly demonstrate subluxation or dislocation of the prosthesis, or even a periprosthetic fracture as the etiology of a patient’s pain (Fig. 7.3). It is important to first understand the “normal” radiographic appearance of a THA, as this will help the surgeon recognize abnormalities that may guide them to their diagnosis.

In a primary THA, the acetabular and femoral components may be cemented or noncemented, although most commonly cementless fixation is currently utilized in the United States. The acetabular component should be assessed for component alignment (often with a target of approximately 40° of abduction and 20° of anteversion based on surgeon preference) and appear well seated without radiolucencies at the bone-implant interface. The femoral head should sit concentrically within the acetabular component, as superior migration of the femoral head indicates polyethylene wear. When a cementless femoral component is used, the well-fixed component demonstrates bone sclerosis and trabeculae extending onto the prosthesis. In the setting of a cemented femoral component, the cement mantle should be approximately 2 mm thick circumferentially and absent of radiolucencies at the bone-cement or implant-cement interfaces.

The importance of serial radiographs in the evaluation of the painful THA cannot be understated as they may guide the physician in assessing component migration, progression of radiolucencies or osteolysis, or new cortical irregularities that may indicate impending fracture, component subsidence, or potentially infection. Whenever possible, prior radiographs should be analyzed to assess a patient’s progression to their current state (Fig. 7.4). Furthermore, if a patient is suspected to have an etiology of pain not in the hip (i.e., lumbar degenerative disease), imaging of that region should be performed. Lastly, a “pre-arthroplasty” radiograph is also useful in determining if there was an appropriate indication for the index THA procedure.