Changes in periacetabular bone mineral density five years after resurfacing hip arthroplasty versus conventional total hip arthroplasty

Abstract

Introduction: We studied whether acetabular bone mineral density (BMD) is better preserved after resurfacing hip arthroplasty (RHA) versus small diameter metal-on-metal total hip arthroplasty (THA). Methods: This randomised controlled trial included 82 patients. BMD was measured in 5 periprosthetic regions of interest (ROI) with dual-energy absorptiometry (DEXA) preoperatively, at 3 and 6 months, 1, 2, 3 and 5 years postoperative. 34 RHA and 26 THA had a complete 5 years follow-up. 1 RHA and 1 THA were revised due to pseudotumour formation, 2 THA were revised because of recurrent dislocations and 1 RHA for avascular necrosis. Results: Overall an initial decrease in BMD was observed for both implants, stabilising after 2 years. 5 years after RHA a BMD change of +1% in upper cranial,-4% (p < 0.01) in cranial,-8% (p < 0.01) in craniomedial,-7% (p < 0.01) in medial and +4% in caudal ROI compared to baseline values was seen. 5 years after THA a BMD change of-3% (p = 0.01),-13% (p < 0.01),-21% (p < 0.01),-11% (p < 0.01) and-2% for each respective ROI. The observed BMD decrease in different regions was structurally favouring the RHA-cup, with significantly higher levels in the cranial and craniomedial ROI. Conclusion: Acetabular BMD is better preserved behind a rigid press-fit convex cup in RHA compared to a titanium threaded cup in conventional THA in the cranial and craniomedial ROI. Despite of a theoretical higher stress-shielding behind the stiff acetabular component in RHA, compared to the more elastic threaded titanium THA-cup, bone depletion behind the RHA component does not seem to be of major concern.

Ceramic-on-ceramic articulation in press-fit total hip arthroplasty as a potential reason for early failure, what about the survivors: a ten year follow-up

“…Several studies in literature could confirm this theory using radiostereometric analysis (RSA) measuring migration by translation and rotation, which is observed mostly in the first six months post-operatively and stabilizes in two to three years post-operatively by osseointegration [ 16 – 20 ]. These results are supported by studies measuring periacetabular bone mineral density (BMD), which changes during osseointegration, showing loss of BMD in the first six months after surgery and restores to baseline in at least two years [ 21 – 23 ]. Brodt et al stated that a limitation of failure of the TH+ to the period of osseointegration could be ruled out [ 12 ].…”

Long-term results of metal-on-metal hip resurfacing in patients 65 years of age or older

“…17 Also, HRA offers a closer to normal biomechanical reconstruction and there is no need for imaging during surgery to reproduce leg length equality and restore anatomic offset. 18 There is also preservation of bone mineral density both in the proximal femur and behind the acetabular cup, 19,20 and this accounts for a lower risk of late periprosthetic fracture, a major cause for hospital readmission. 21 Finally, HRA provides the patient with greater confidence in the construct, as shown in recent gait analysis studies.…”