Innovations in Hip Arthroplasty
Clinical Results of a Modular Neck Hip System: Hitting the "Bull's-Eye" More Accurately
Paul J. Duwelius, MD, Mark A. Hartzband, MD, Robert Burkhart, PA, Clay Carnahan, PA, Scott Blair, BS, YingXing Wu, MD, and Gary L. Grunkemeier, PhD
Dr. Duwelius is Adjunct Associate Professor of Orthopedic Surgery, Oregon Health and Science University, Portland, Oregon, and Clinical Attending, Orthopedic and Fracture Clinic, Providence St. Vincent Medical Center, Portland, Oregon.
Dr. Hartzband is Director, Joint Replacement Service, Hackensack University Medical Center, Hackensack, New Jersey.
Mr. Burkhart and Mr. Carnahan are Physician Assistants, Orthopedic and Fracture Clinic, Providence St. Vincent Medical
Center, Portland, Oregon.
Mr. Blair is a medical student, University of Kansas Medical School, Kansas City, Kansas.
Dr. Wu is Biostatistician, and Dr. Grunkemeier is Director, Medical Data Research Center, Providence Health and Services,
Portland, Oregon.
In this article, we present 2-year clinical results of a modular neck tapered hip stem, based on 634 patients from a 2-center study. Nearly half of the patients in this series required use of a head center location offered by the modular neck stem but not available in a nonmodular stem with an identical body. The modular neck enabled femoral-first preparation, which facilitates establishing the desired total version of the reconstruction. No fractures of a stem or modular neck occurred, and there were no dissociations of the head-neck junction. There were no complications or revisions related to the femoral implant. Optimal leg length, femoral offset, and total version are goals in total hip arthroplasty. Neck modularity improves the ability to re-create the head center to achieve these goals and to hit the “bull’s-eye” in total hip arthroplasty.