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Etidronate Effective for Preventing Bone Loss after Total Hip Arthroplasty

Cyclic treatment with etidronate after total hip arthroplasty (THA) prevented significant bone loss in the proximal and middle femoral neck regions, according to a recent Japanese study.

THA is often recommended for arthritic patients who do not respond to conservative treatments. However, one disadvantage of cementless THA is that as the stem takes the mechanical load from the femur, proximal femoral bone resorption occurs, which can lead to femoral fracture and late stem loosening.

One potential solution is to add osteoactive drugs to post-THA management. In particular, bisphosphonates are an emerging class of drugs used to treat osteoporosis and other bone disorders by preventing bone resorption. Their effectiveness in treating proximal femoral bone mineral density (BMD) decrease after THA, however, is still under evaluation.

Katsuyuki Yamaguchi with the Kaizuka City Hospital, Osaka, and colleagues assessed the effects of the bisphosphonate drug etidronate on BMD following cementless total THA.

The prospective study included 51 patients (40 postmenopausal women and 11 men, average age 68) that had undergone a primary cementless THA. Patients were randomised to receive either cyclic etidronate (cycles of 400 mg/day orally for 2 weeks followed by 12 weeks of 500 mg/day calcium lactate) or no osteoactive drugs.

The periprosthetic BMD at 7 Gruen zones was measured at 3 weeks, 6 months, and 12 months after surgery using dual energy X-ray absorptiometry (DXA). Markers of bone turnover, namely bone alkaline phosphatase (BAP) and type I collagen N-telopeptide breakdown products (NTX) were also analysed.

Overall, etidronate was effective at preventing declining bone loss in the proximal (zones 1 and 7) and middle (zones 2 and 6) femoral neck regions. The most striking effect was in the proximal zone 7, which after 12 months showed a 30% decrease in BMD in the no treatment group and only a 14% decrease with etidronate, which was not statistically different from baseline.

The effects of etidronate were observed at 6 months in proximal zones 1 and 7 and were maintained up to 12 months after surgery in these regions. However, the benefits in the middle areas, zones 2 and 6, were not apparent until 12 months. Furthermore, no significant effects were seen in the distal regions (zones 3-5).

The BMD results were supported by analysis of urinary NTX and serum BAP levels, wherein a significant reduction in these markers was seen after 12 months of etidronate treatment.

Adverse events were not reported in this study, though 1 patient receiving etidronate was excluded due to treatment-related gastrointestinal symptoms.

The authors conclude that "cyclic therapy with etidronate may help to reduce the resorptive changes in the proximal part of the femur after cementless THA." They further note that "follow-up study with larger populations will be required to define the potential efficacy of intermittent cyclic etidronate therapy on postoperative bone loss."



Bone 2003 Jul;33:1:144-9. "Cyclic therapy with etidronate has a therapeutic effect against local osteoporosis after cementless total hip arthroplasty"

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