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The dual mobility hip bearing concept combines a small bearing with a large diameter bearing through a dual articulation system, potentially increasing the stability of the hip. Bearings with two articulations introduce concerns of whether or not wear might be increased compared to a conventional bearing. We therefore evaluated the wear performance of a(More)
Steep cup abduction angles with adverse joint loading may increase traditional polyethylene bearing wear in total hip arthroplasties. However, there have been few reports evaluating the effect of cup inclination on the wear of dual-mobility devices. In a hip joint simulation, we compared the short-term wear of two-sizes of modular highly cross-linked(More)
BACKGROUND Dual-mobility acetabular cups have been marketed with the purported advantages of reduced dislocation rates and improvements in ROM; however, the relative efficacies of these designs in terms of changing joint stability via ROM and dislocation distance have not been thoroughly evaluated. QUESTIONS/PURPOSES In custom computer simulation studies,(More)
Smaller head sizes and head/cup ratios make cups smaller than 50mm and larger than 58mm, more prone to dislocation. Using computer modeling, we compared average head sizes and posterior horizontal dislocation distance (PHDD) in two 78-patient matched cohorts. Cup sizes were small (≤50mm) or large (≥58mm). The control cohort had conventional fixed bearing(More)
This study assessed the accuracy of preoperative digital templating for a second-generation cementless stem compared with its first-generation design. A prospective cohort of 100 consecutive patients who had undergone a primary total hip arthroplasty using a new second-generation cementless stem was compared with the prior 100 hips that had received the(More)
The purpose of this study was to compare in vivo fit and fill analysis of a new second-generation proximally coated cementless stem compared to its predicate design. This prospective trial of 100 total hip arthroplasties compared specific radiographic "Fit and Fill" parameters between the two designs. Fit type was assessed by comparing the type of canal(More)
Most current tapered wedge hip stems were designed based upon the original Mueller straight stem design introduced in 1977. These stems were designed to have a single medial curvature and grew laterally to accommodate different sizes. In this preclinical study, the design and verification of a tapered wedge stem using computed tomography scans of 556(More)
The modern generations of cementless hip arthroplasty implant designs are based on precise fit and fill of components within the native bony geometry of the proximal femur and the acetabulum for enhanced implant longevity. Variations exist based on a number of population demographics such as age, gender, body mass index, and ethnicity. Recently,(More)
Nitrogen ion implantation (which considerably hardens the surface of the bearing) may represent one possible method of reducing the wear of metal-on-metal (MOM) hip bearings. Currently there are no ion-implanted MOM bearings used clinically. Therefore a physiological hip simulator test was undertaken using standard test conditions, and the results compared(More)
BACKGROUND It is advocated that to avoid complications associated with femoral stem impingement, acetabular positioning should be within a "safe zone." However, instability remains prevalent despite accurate cup positioning, with studies showing dislocations of cups despite positioning within safe zones. We assessed cup position angles associated with(More)