Core Decompression for Non-traumatic Osteonecrosis of the Femoral Head

Justin de Beer, M.D., FRCSC
Director Hamilton Health Sciences Arthoplasty Programme
Director Hamilton Arthroplasty Group
Assistant Clinical Professor, McMaster University
Hamilton, ON

Core decompression is an uncommonly performed procedure, accounting for only 2.2% of all hip surgery procedures in one reported series1. Nonetheless, core decompression has become a well-established option in the treatment of non-traumatic osteonecrosis. Non-traumatic osteonecrosis of the femoral head is known to be associated with multiple aetiological factors yet both the natural history and the precise pathogenesis remain unclear. While not conclusive, several observational studies have suggested a decreased rate of progression of the disease process and less femoral head collapse with surgical intervention.2-6 Core decompression has the advantage of surgical simplicity with a low risk of morbidity; affording satisfactory results in appropriately selected patients. One hypothesis regarding the pathogenesis has proposed that the osteonecrosis occurs secondary to venous infarction resulting in a form of intraosseous compartment syndrome7,8. While remaining unproven, this concept intuitively provides support for the role of core decompression as a surgical procedure in this clinical setting.

The classical surgical technique involves the use of either an 8 - 10mm trephine or drill introduced from the lateral cortex of the proximal femur through the neck and into the avascular segment4. As previously stated, core decompression is an uncommon procedure whereas most surgeons are very familiar with the use of a dynamic hip screw device for fracture fixation. The may lead to a tendency to place the insertion point of the trephine/drill too distally in the lateral cortex which should be avoided to reduce the risk of subsequent iatrogenic proximal femoral fracture. Some authors have suggested that supplementing the core decompression procedure by inserting cancellous graft, a fibular strut (vascularised/nonvascularised), BMP or a combination, into the core defect created, may result in added clinical benefit4,5. These issues remain controversial and are beyond the scope of this article.

An alternative surgical technique has been to use a three mm K-wire or drill to make multiple smaller drill holes from the proximal lateral femoral cortex up into the avascular segment. This technique has been reported to produce outcomes equivalent to those reported for the larger single trephine/drill hole technique in regards to disease progression and femoral head collapse with a lower risk of proximal femoral fracture.9

The surgical aims of core decompression include symptomatic relief and the arrest of disease progression with prevention of femoral head collapse and secondary arthrosis, which would otherwise result in the need for future arthroplasty. The issue of recommending core decompression for patients in the absence of symptoms remains controversial. However, a case series reported by Belmar et al6 specifically addressed this issue and noted improved outcomes in hips treated surgically as compared to those treated without surgery even when those patients were asymptomatic.

Patient selection is clearly a critical success factor and most series have reported satisfactory results when applied to the pre-collapse stages of osteonecrosis (Steinberg4 Stage 2) although Bozic et al10 warned of inferior outcomes if cystic changes are present in the femoral head. Simank et al3 also cautioned that inferior results are likely in patients >40 years of age and with the continuing use of systemic steroids. On occasion, core decompression may be effective in more advanced stages. Mont et al11 reported a series of core decompression procedures performed in patients all with Steinberg4 Stage 3 disease, achieving 59% survival rates at a mean 12-year follow-up. These results improved to 89% when applied to a subgroup with central (Ohzono12 Type B) lesions and with a combined Kerboul13 necrotic angle <250. These outcomes were achieved irrespective of the primary diagnosis.

Despite moderate study quality and a limited pool of relevant studies in the literature, reported observational studies have provided a considerable body of evidence for the continued use of this procedure in the early stages of non-traumatic osteonecrosis of the femoral head. Further, in a recently published study of the cost effectiveness of core decompression in the treatment of early osteonecrosis of the femoral head, using good methodological rigour, Soohoo et al14 concluded that core decompression is indeed a highly cost-effective treatment that has the potential to delay the need for total hip arthroplasty for five years or longer.


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