ABSTRACT
BACKGROUND: Resurfacing is a popular alternative to a standard hip replacement in young arthritic patients. Despite bone preservation around the femoral component, there is little information regarding the bone quality. PATIENTS AND METHODS: 32 patients underwent consecutive Birmingham hip resurfacing. The bone density of the femoral neck was measured preoperatively and then at 6 weeks, 3 months, 1 year, and 2 years. The femoral neck was divided into regions of interest. Results were available for 27 hips in 26 patients. RESULTS: The overall femoral neck bone density showed a trend towards a decrease at 6 weeks and 3 months but returned to the preoperative level at 1 year, and was maintained at 2 years. The combined superior regions of the neck showed a statistically significant decrease in bone density at 6 weeks and 3 months. This returned to preoperative levels at 1 year and was maintained at 2 years. INTERPRETATION: Bone density appears to decrease at 6 weeks and 3 months, suggesting that care is necessary until bone density begins to recover.
Subject(s)
Arthroplasty, Replacement, Hip , Bone Density , Femur Neck/physiology , Absorptiometry, Photon , Adult , Aged , Arthroplasty, Replacement, Hip/adverse effects , Arthroplasty, Replacement, Hip/methods , Female , Femur Neck/diagnostic imaging , Hip Prosthesis/adverse effects , Humans , Male , Middle Aged , Postoperative Period , Preoperative Period , Prospective Studies , Prosthesis Design , Time FactorsABSTRACT
INTRODUCTION: Dual energy X-ray absorptiometry (DEXA) has been used to measure bone mineral density (BMD) around total hip prostheses. With the recent increase in the use of metal-on-metal hip resurfacing, such as the Birmingham hip resurfacing (BHR), we aimed to produce a reliable method of measuring bone density around a metal-on-metal hip resurfacing. METHODS: We performed DEXA scans on 5 patients (7 BHRs), who had undergone resurfacing with the BHR within the past 2 years. A zonal reporting technique was devised and evaluated. RESULTS: The intraclass correlation (i.e. the correlation between any two assessments of one region of interest) was 0.997, with an overall coefficient of variation of 5%. INTERPRETATION: We have designed and demonstrated a safe, noninvasive and highly reproducible method for interpreting and reporting the results of DEXA scanning of BHR implants in vivo. We will now use this method to prospectively study our BHR population to assess the changes in bone density following BHR within the femoral neck. This method may add to the current techniques available for detection of impending failure.
