Patients typically present with groin pain, although 10% to 15% may have nonspecific symptoms such as trochanteric or buttock pain. It is sometimes reasonable to consider a diagnostic hip injection with a local anesthetic to rule out other pathology such as lumbar disc disease. Often a patient with occult osteonecrosis may have nonspecific hip, trochanteric, or buttock symptoms that radiate from the back or another pathologic entity.

The patient’s age, activity level, general health, and prior surgical history help to individualize the proposed treatment. The presence of severe systemic illness or a short life expectancy may preclude a major surgical procedure or may lead to the decision to perform one definitive procedure (arthroplasty). However, a young patient may better tolerate surgical procedures, so preservation attempts are appropriate or if arthroplasty is necessary they may require a more durable bearing surface. Thus, similar lesions may need to be treated in different ways depending on the patient history, demographic variables, lifestyle demands, and activity levels.

For example, a unifocal osteonecrotic lesion in the hip of an active, 34-year-old patient with a prior vascularized free fibular graft will require different instrumentation, approaches, and choice of components than a lower demand 65-year-old patient who developed a similarly located and sized lesion as a consequence of chemotherapy for a malignancy. In the first case, revision of a bone-grafting procedure may require special surgical equipment and lead to a longer operative time whereas the second case is likely to be a relatively uncomplicated arthroplasty. Conversely, bearing choice is far more critical in the first case where the patient needs a durable bearing surface and a stable hip through a large range of motion arc, unlike the second case where the patient who is relatively less active may suffice with a traditional bearing option.

Prior surgical procedures may increase the difficulty of performing an arthroplasty and must be considered prior to surgery. Although many patients who have undergone prior surgical procedures will likely have received a core decompression or percutaneous drilling, that facilitates easy component placement, dysplastic patients who have undergone osteotomies or vascularized fibular grafting may present with retained hardware. Similarly, patients who present with posttraumatic osteonecrosis may have sustained multiple extremity injuries, and apart from hardware present in the hip joint area there may be anterograde or retrograde femoral nails, or in less common cases, femoral plates, which may make placement of a femoral stem for a hip arthroplasty difficult and increase surgical morbidity because of the need for multiple incisions, increased operative time, and potential blood loss. In the posttrauma setting, it has been estimated that 15% of all hardware removals are performed in preparation for total hip arthroplasty (27). With femoral nails in particular, unreamed nails may become incarcerated, thus making removal difficult. Furthermore, the removal of proximal interlocking screws may potentially create a stress riser or risk for refracture (28,29). Even after successful nail removal, up to 20% of patients have reported residual pain, which may affect their perceived satisfaction with their total hip arthroplasty (30).

One should consider that this disease is often bilateral (range, between 50% and 100%, with bilaterality greater than 80% in some large series). When planning treatment, the surgeon may consider staging hip arthroplasties to allow for the patient to rehabilitate one hip before proceeding to the contralateral side. However, if a small procedure (e.g., core decompression) is planned for one side, then performing both procedures at one sitting is appropriate. In general, as with osteoarthritis, the more clinically symptomatic hip should be addressed first, unless one is trying to save the less symptomatic hip. Of note is that in approximately 10% of patients, other joints exhibit osteonecrosis. If a patient has pain in other joints, such as the knee, shoulder, or ankle, they should be investigated with radiographs and possibly an MRI to describe further disease and to develop a treatment plan.

The etiology of the osteonecrotic lesion should always be considered since the presence of some risk factors may predispose patients to additional postoperative complications, such as delayed wound healing or infection. In particular, human immunodeficiency virus (HIV) infection and associated antiretroviral therapy have been implicated as causes of osteonecrosis and poor outcomes (31). These patients, however, have been observed to have higher rates of periprosthetic infection as a consequence of their immunodeficient state (32,33,34). In a recent study of HIV-positive patients who underwent lower extremity total joint arthroplasty, 29% (6 of 21 joints) developed a periprosthetic infection at a mean follow-up of 10 years (35).

In summary, numerous clinical factors including age, etiology of disease, and patient comorbidities may influence the choice of treatment for osteonecrosis of the femoral head. However, radiographic factors and staging should typically take precedence over these factors. For example, even
though a teenager might prefer avoiding a total hip arthroplasty, this choice may not be appropriate if radiographically detectable arthritic changes are present on both sides of the joint. In the next section we discuss the relevant radiographic factors that should be evaluated with these patient-specific factors to create an appropriate treatment plan.

Collapse represents mechanical failure of the weakened necrotic bone. Although large areas of collapse can be recognized by a change in the contour of the femoral head, this may not be as obvious in heads without substantial depression. An early indicator is the crescent sign (16). When collapse is present it is likely that the patient will eventually require a total hip arthroplasty and attempting head-preserving procedures will likely only increase surgical morbidity as a consequence of further procedures secondary to disease progression (39). Collapse may be characterized using CT scans in some lesions (40).