Which prophylactic interventions are used in the management of femoral head avascular necrosis (AVN)?

Updated: Oct 22, 2018
  • Author: John D Kelly, IV, MD; Chief Editor: Craig C Young, MD  more...
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Answer

See the list below:

  • Prophylactic measures

    • The most commonly performed prophylactic surgical intervention is core decompression, whereby one or more cores of necrotic femoral head bone is removed in order to stimulate repair. [11] Core decompression is often supplemented with bone grafting (cancellous autograft or structural allograft) to enhance mechanical support and augment healing. Biologic augmentation of core decompression includes the addition of demineralized bone matrix, bone morphogenic proteins, or electric/electromagnetic stimulation. [12] These agents are purported to either enhance bone formation or decrease bone resorption in the hope of maintaining the structural integrity of the femoral head. Biologic augmentation of core decompression alone offers therapeutic benefit—if it is instituted before subchondral collapse (Steinberg stage III). [12]  A study analyzed the clinical, functional and radiological outcome of core decompression and bone grafting in 20 patients with 28 cases of osteonecrosis of the femoral head (ONFH) up to stage IIB (Ficat & Arlet). The study concluded that core decompression and bone grafting provide satisfactory outcome when patients are carefully selected in early stages of the disease (stage I), before the stage of collapse. However patients with stage II disease had poorer outcomes approximately 50% with improvement. [13]

    • The addition of a vascularized fibular graft to core decompression offers promise in cases with more advanced lesions, but this procedure involves considerable morbidity. One study indicated that vascularized fibular grafts were more effective in preventing femoral head collapse than nonvascularized fibular autografts. [14, 15]

    • The results of prophylactic measures for femoral head AVN have considerable variation, but certain generalizations can safely be stated. Namely, the clinical results of core decompression alone deteriorate with more advanced lesions. [12] The addition of cancellous bone grafting appears to slightly enhance clinical outcomes if subchondral fracture is present. [14] The addition of demineralized bone matrix to core decompression confers little (if any) clinical response, and the effects of bone morphogenic protein remain uncertain.

    • The supplemental implementation of electrical stimulation with core decompression has provided disappointing results. [12] Low-frequency pulsed electric and magnetic fields may offer more promise, but clinical results thus far are inconclusive. The placement of a structural graft through a core tract into the femoral head generally yields disappointing results. However, grafts placed into the femoral neck or directly into the femoral head are more promising. Free vascularized fibular grafting significantly alters disease progression in precollapse lesions and is even useful in modifying disease in mildly collapsed and early arthritic hips. [14]  The best responses to treatment with pulsed electromagnetic fields were seen in early Ficat stages, however, further studies are needed. [16]

    • Osteotomies are performed in attempt to move necrotic bone away from primary weight-bearing areas in the hip joint. Osteotomies can be angular or rotational, with the latter proving to be much more technically difficult. These techniques may delay arthroplasty, but they are best suited for small precollapse or early postcollapse of the femoral head in patients who don't have an ongoing cause of AVN. However, osteotomies make subsequent arthroplasty more challenging and, unfortunately, these procedures are associated with an appreciable risk of nonunion.

    • The role of arthroscopy to better stage the extent of disease has emerged. Arthroscopic evaluation of the joint can help better define the extent of chondral flaps, joint degeneration and even joint collapse and may help with the temporary relief of synovitis. [17] Arthroscopic-assisted reduction of the head collapse is experimental at this time.


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