Equal primary fixation of resurfacing stem, but inferior cup fixation with anterolateral versus posterior surgical approach. A 2 year blinded randomized radiostereometric and Dual X-ray Absorptiometry study of metal-on-metal hip resurfacing arthroplasty

• Published in: The Journal of arthroplasty 2017
• Main Authors: Hjorth, Mette Holm, MD, Lorenzen, Nina Dyrberg, MD, Ph.d, Søballe, Kjeld, MD, DMSc, Jakobsen, Stig Storgaard, MD, PhD, Stilling, Maiken, MD, PhD
• Format: Article
• Language: English
• Subjects: Orthopedics
• ISSN: 0883-5403
• DOI: 10.1016/j.arth.2017.05.034

Abstract Background The antero-lateral (AntLat) surgical approach may spare the blood supply to the femoral head and improve the accuracy of cup positioning in hip resurfacing arthroplasty (MoM HRA). Thereby potentially lessen complications such as avascular head necrosis, femoral neck narrowing and fracture, improve implant fixation and lessen periprosthetic bone mineral density (BMD) loss. Material and Methods Between November 2008 and January 2012, a randomized clinical trial was performed at XXX University Hospital. 49 patients (28 males) were allocated to MoM HRA by the AntLat (n=25) or the Post (n=24) surgical approach. Patients were followed with radiostereometric analysis, measurements of periprosthetic BMD, clinical outcome scores of Harris Hip Score (HHS) and Visual Analogue Scale (VAS), serum metal-ions, and conventional radiographs. Results At 3 months, cups in the AntLat group had higher total translations (TT) of mean 1.00 ± 0.70 mm versus mean 0.64 ± 0.45 mm in the Post group (p=0.04), and higher total rotations(TR) of mean 2.44 ± 1.36 ° versus mean 1.39 ± 1.17 ° in the Post group (p=0.002). All migrations of cup and stem were similar at 1 and 2 years postoperative (p>0.07). At 1 year, periprosthetic BMD since postoperative at the medial side of the stem was reduced to mean 98.45 ± 8.57 % in the AntLat group, and increased to mean 105.57 ± 11.07 % in the Post group (p=0.02), but measurements were comparable at 2 years (p=0.05). Outcome scores of HHS and VAS, and serum metal-ions were similar (p>0.09). Conclusion Cups inserted by the AntLat approach migrated more until 3 months postoperative. This illustrates a less good primary cup fixation with the AntLat approach; however, all cups were well-fixed after 3 months’ follow-up indicating a good secondary fixation.