Bone mineral density in the femoral neck increases after hip resurfacing: a cohort with five-year follow-up

Prediction of Bone Mineral Density (BMD) Adaptation in Pelvis-Femur Model with Hip Arthroplasties

The prediction of bone remodeling behaviour is a challenging factor in encouraging the long-term stability of hip arthroplasties. The presence of femoral components modifies the biomechanical environment of the bone and alters the bone growth process. Issues of bone loss and gait instability on both limbs are associated with the remodeling process. In this study, finite element analysis with an adaptive bone remodeling algorithm was used to predict the changes in bone mineral density following total hip and resurfacing hip arthroplasty. A three-dimensional model of the pelvis–femur was constructed from computed tomography (CT-based) images of a 79-year-old female patient with hip osteoarthritis. The prosthesis stem of the total hip arthroplasty was modelled with a titanium alloy material, while the femoral head had alumina properties. Meanwhile, resurfacing of the hip implant was completed with a cobalt-chromium material. Contact between the components and bone was designed to be perfectly bonded at the interface. Results indicate that the bone mineral density was modified over five years on all models, including hip osteoarthritis. The changes of BMD were predicted as being high between year zero and year one, especially in the proximal region. Changes were observed to be minimal in the following years. The bone remodeling process was also predicted for the non-operated femur. However, the adaptation was lower compared to the operated limbs. The reduction in bone mineral density suggested the bone loss phenomenon after a few years.

What should I expect from my recalled Adept Hip Resurfacing?

"My Hip Resurfacing (HR) has been recalled. What will happen to me?" This is the question of every patient who underwent an implant recall, a highly stressful event for both patients and physicians. Triggered by a 11.64% failure rate at 7 years, a recall process started for Adept HR with head diameter less than 48 mm. We report our experience in the recall process of 40 patients with the above-mentioned components. One patient underwent revision surgery due to an adverse reaction to metal debris at 5-year follow-up. None of the patients were scheduled for revision, with an estimated survival rate of 97.6% at 7 years. Implants were well positioned with an average acetabular inclination angle of 37°. Cobalt and chromium blood levels were below the safety threshold of clinical relevance. Functional scores were excellent. In the case of a well-positioned device with normal ion levels, a good performance of the implant is generally observed. Even if we experienced a very low revision rate, this may certainly get worse over time since not all possible failures are predictable, thus requiring a careful periodic follow-up.

Hip resurfacing

Hip resurfacing has been proposed as an alternative to traditional total hip arthroplasty in young, active patients. Much has been learned following the introduction of metal-on-metal resurfacing devices in the 1990s. The triad of a well-designed device, implanted accurately, in the correct patient has never been more critical than with these implants.

Following Food and Drug Administration approval in 2006, we studied the safety and effectiveness of one hip resurfacing device (Birmingham Hip Resurfacing) at our hospital in a large, single-surgeon series. We report our early to mid–term results in 1333 cases followed for a mean of 4.3 years (2 to 5.7) using a prospective, observational registry. The mean patient age was 53.1 years (12 to 84); 70% were male and 91% had osteoarthritis. Complications were few, including no dislocations, no femoral component loosening, two femoral neck fractures (0.15%), one socket loosening (0.08%), three deep infections (0.23%), and three cases of metallosis (0.23%). There were no destructive pseudotumours.

Overall survivorship at up to 5.7 years was 99.2%. Aseptic survivorship in males under the age of 50 was 100%. We believe this is the largest United States series of a single surgeon using a single resurfacing system.

Cite this article: Bone Joint J 2016;98-B (1 Suppl A):10–13.