INDICATIONS

The diagnostic indications for THA most commonly include primary osteoarthritis, inflammatory arthritis, avascular necrosis, femoral neck fracture, femoral neck nonunion or malunion, and hip dysplasia. The indications for THA from over 8100 THAs performed at our institution over the past 20 years are represented in Table 9-1. Each indication is discussed in detail in this chapter. Osteoarthritis was the most common indication for THA, followed by avascular necrosis, inflammatory arthropathies, and following proximal femoral fracture.

TABLE 9-1 SURGICAL INDICATIONS FOR 8102 PRIMARY TOTAL HIP ARTHROPLASTIES: 1986 TO 2006

Patient age is a factor to consider in the context of considering the indications for THA. Younger individuals may greatly benefit from the pain relief and functional improvement from a THA but need to be informed that they are at risk for single or multiple revisions in their lifetime. “Waiting as long as possible” is often a wise concept, but many patients with advanced avascular necrosis, developmental dysplasia of the hip, or rheumatoid arthritis still make excellent candidates due to their high levels of pain and functional impairment. These diagnoses are found in younger patients undergoing THA in our series (see Table 9-1). The surgeon should consider appropriate implant fixation interfaces and bearing surfaces in patients in whom the implant may be required to last into a third decade of use, as is the case with many younger individuals.¹^–⁴

Hip disease can often present with a spinal pathologic process; clear diagnosis related to the hip as the primary cause of the pain and disability is critical. A careful history, physical examination, including gait analysis, and imaging studies to evaluate the hip and spine are important steps when considering THA. If the relative role of hip and back pathology is unclear, the utilization of an intra-articular hip injection with 5 to 10 mL of 1% lidocaine performed under fluoroscopy can be very helpful for diagnosis. The amount of pain relief provided during weight bearing and range of motion after this injection is an indication of the results generally observed after THA. This diagnostic test is very helpful in confirming the surgical indications for THA in the presence of coexisting spinal disease.

Primary osteoarthritis of the hip is the most common indication for THA at our center (see Table 9-1) and in most series of THA (Fig. 9-1). Osteoarthritis may result from many causes and has been demonstrated to affect the medial, superior, and lateral aspects of the hip.⁵ The location of osteoarthritis has implications on implant selection and survivorship. Mechanical cam-type impingement from malalignment, slipped capital femoral epiphysis, or Legg-Calvé-Perthes disease has been associated with hip arthrosis, most notably in younger individuals. Cam impingement has recently become the focus of nonarthroplastic treatment of early hip disease through osteotomy and débridement techniques⁶ and has been discussed in preceding chapters.

FIGURE 9-1 Osteoarthritis: anteroposterior radiograph demonstrating osteoarthritis with loss of superior joint space, flattening of the femoral head, central acetabular osteophyte formation with lateral femoral head displacement, subchondral sclerosis, and inferior femoral head and acetabular osteophytes.

Avascular Necrosis

Avascular necrosis results in loss of femoral head integrity and eventual collapse of subchondral bone with resulting joint incongruity (Fig. 9-2A). MRI helps confirm the diagnosis when plain radiographs are inconclusive (see Fig. 9-2B). Causes of avascular necrosis include excess alcohol consumption, systemic corticosteroid administration, displaced femoral neck fractures, traumatic hip dislocations, irradiation, or idiopathic categories.⁷ Osteonecrosis following irradiation of the pelvis is an indication for THA. Implant selection is important because both cemented and uncemented implants have been reported to have decreased clinical survivorship in hips that have been irradiated,⁸ although in recent years total hip arthroplasty using modern generation uncemented components in patients with irradiated pelvis has had encouraging outcomes.⁹