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Treatment Alternatives

Osteonecrosis of the femoral head should be viewed as a disease with a broad spectrum of pathologic presentations that can warrant various modalities of treatment. The goals of treatment are pain relief, maintenance of a congruent hip joint, and, if possible, delay or prevention of the need for total hip replacement. Since this disease commonly affects a younger population, it is advantageous to consider performing procedures that preserve the femoral head, because with time, further interventions may be necessary1-4.

Four parameters are commonly evaluated when determining treatment:
  1. presence of collapse
  2. size of lesion
  3. extent of femoral head depression
  4. acetabular involvement
On the basis of these factors, an algorithm that involves performing the least invasive procedure allowable by the findings is proposed.

Table 2. A proposed treatment algorithm based on findings of radiographic and magnetic resonance imaging.
Radiographic and MRI Findings Symptoms Procedure
Normal radiographs, MRI+* Asymptomatic Observation; medical interventions (vasodilators, lipid-lowering agents, anti-coagulants); consideration of core decompression
MRI+*; small & medium combined necrotic angle†; pre-collapse° Symptomatic Core decompression
MRI+*; large combined necrotic angle; pre-collapse°; post-collapse° with <2 mm depression Symptomatic Bone grafting, vascularized or nonvascularized; osteotomy
Post-collapse° with >2 mm depression Symptomatic Limited femoral resurfacing
Acetabular involvement Symptomatic Total hip replacement
*MRI positive = lesion seen on MRI;†small and medium combined necrotic angle = combined necrotic angle <200º; large combined necrotic angle is >200º; ° as seen on plain radiographs.

The success rates of these different procedures are demonstrated in Figure 2, which represents results over a mean follow-up of nine to twelve years2.



Fig. 2. Comparison of treatment results based on the severity of the lesion2. The figure represents results over a mean follow-up of nine to twelve years2.

The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. The Orthopaedic Research and Education Foundation and commercial entities (Merck, Stryker Howmedica Osteonics, Wright Medical Technology, Genetics Institute, Pharmacia, Nutramax, and Exactech) paid or directed, or agreed to pay or direct, benefits to a research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.
References
1. Mont MA, Hungerford DS. Nontraumatic avascular necrosis of the femoral head. J Bone Joint Surg Am. 1995;77: 459-74.
2. Mont MA, Jones LC, Sotereanos DG, Amstutz HC, Hungerford DS. Understanding and treating osteonecrosis of the femoral head. Instr Course Lect. 2000;49:169-85.
3. Steinberg ME, Bands RE, Parry S, Hoffman E, Chan T, Hartman KM. Does lesion size affect the outcome in avascular necrosis? Clin Orthop. 1999;367:262-71.
4. Steinberg ME, Hayken GD, Steinberg DR. The "conservative" management of avascular necrosis of the femoral head. In: Arlet J, Ficat RP, Hungerford DS, editors. Bone circulation. Baltimore: Williams and Wilkins; 1984. p 334-7.

(continued next month in Part 2)

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