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"Uncemented resurfacing is better."
Not a myth! My data demonstrate that it is better. In my study , the excess failure rate due to loosening of the cement is 1% at 10 years. That does not seem like much. But if I used cement, my failure rate would double. My failure rate due to any cause is currently <1% by 15 years.
All hip resurfacings have an uncemented (porous, bone ingrowth) socket. Most have a cemented femoral component. The Recap/Magnum metal-metal implant that I use, and Jim Pritchett’s metal-poly implant are both completely porous.
Cement offers immediate fixation but kills some bone in the curing process. Late failure can occur due to cement fatigue. Porous fixation requires an initial tight press fit and time for ingrowth. Failure of ingrowth has never occurred in >5000 of my cases. Once ingrown, a porous coating is more durable than cement.
I could find no evidence that early femoral failure due to fracture or head collapse was affected by the choice of fixation (cement vs uncemented). However, by ten years the rate of femoral loosening was 0.9% vs 0.04%.
Cement actually works much better than I predicted 20 years ago. The cement in a femoral resurfacing is generally loaded in compression which is favorable for cement. Cement fixation in resurfacing has therefore done much better than cement in total hips and total knees.
Cement seems to work especially well if the femoral head bone is hard and there are no large defects. If the bone defects are cavitary and can be filled with bone graft and cemented over, the outcome is better than if the defect is filled with exothermic cement. In osteonecrosis, the defects tend to be segmental which makes it hard to use this grafting technique, so the outcome is worse. In osteoporotic bone, the cement also penetrates more deeply into the bone and burns more bone causing more failures. That is why McMinn has more failures in older women. Cement works best in hard bone and with contained defects that are grafted.
Porous fixation is technically easier, works in all cases, can be used in cases with extensive bone loss, and carries the theoretical advantage for long-term fixation well beyond 10 years.
Currently, my 15-year implant survivorship is 99% with fully porous Zimmer Biomet Recap/Magnum metal-metal Hip resurfacing in over 5000 cases. I do not exclude people based on age, sex, diagnosis, or implant size. I resurface heads with up to 50% bone loss in younger patients. No one can match these results – with the BHR or any other device.
1. Gaillard-Campbell, D.M. and T.P. Gross, Femoral Fixation Methods in Hip Resurfacing Arthroplasty: An 11-Year Retrospective Comparison of 4013 Cases. J Arthroplasty, 2019. 34(10): p. 2398-2405.