The National Joint Registry of England, Wales, Northern Ireland, and the Isle of Man (NJR) monitors the performance of primary total hip arthroplasty (THA) implants and summarizes usage and outcomes for specific hip systems. The objectives of this study were to 1) determine if survivorship for the PROCOTYL® L acetabular cup, a hemispherical press-fit cup coated with hydroxyapatite and a metal on XLPE articulation, is significantly different from all other cementless cups in the NJR and 2) to analyze patient reported outcomes measures (PROMs) at a minimum five year follow-up for the subject cup. The database of the NJR was searched for demographic information and survivorship data for all THAs performed with the PROCOTYL® L cup (metal on XLPE) and all other cementless cups. Survivorship data for both groups was adjusted to exclude metal on metal bearings and compared for all revisions and acetabular revisions only. The Cox Proportional Hazards model for the revision risk ratio of the subject cup to all cementless cups was also calculated. Patients with the subject cup implanted for at least five years were mailed a PROMs program questionnaire consisting of the Oxford Hip, EQ-5D, and EQ VAS scores. No pre-operative PROMs scores were collected.Introduction
Methods
Total hip replacement is increasingly being conducted in younger and more active patients, so surgeons often use bearing surfaces with improved wear characteristics, such as ceramic on ceramic. The primary objective of this study was to determine if survivorship for a BIOLOX® delta ceramic on delta ceramic couple used with the PROCOTYL® L acetabular cup is significantly different from all other cementless cups in a large arthroplasty registry. The secondary objective of this study was to analyze patient reported outcomes measures (PROMs) of the subject cup with a minimum five year follow-up. Patient demographics and survivorship data was collected from the National Joint Registry of England, Wales, Northern Ireland, and the Isle of Man (NJR) database for all total hip replacements performed with the PROCOTYL® L cup used in combination with a delta-on-delta articulation, as well as for all other cementless cups. Survivorship data was compared for all revisions and cup revisions only and data was adjusted to exclude metal on metal articulations. The hazard ratio of the subject system to all cementless cups was also calculated with the Cox Proportional Hazards model. Patients with the subject components implanted for a minimum of five years completed Oxford Hip, EQ-5D, and EQ VAS score questionnaires.Objectives
Methods
Modularity in total knee arthroplasty, particularly in revisions, is a common method to fit the implants to a patient's anatomy when additional stability or fixation is needed. In such cases, it may be necessary to employ multiple points of modularity to better match the anatomy. Taper junction strength at each of these levels is critical to maintain the mechanical stability of the implant and minimize micromotion. This effect of distributed assembly loads through multiple tapers and the resulting strength of the construct have not been previously evaluated on this revision tibial implant. The purpose of this study was to evaluate the possible dissipation of impaction force through multiple taper connections as compared to a single connection. Two different constructs representative of modular implants were studied: a construct with a single axial taper connection (Group A; representing implant-stem) was compared to a construct with an adaptor that included two, offset, modular taper connections (Group B; representing implant-adapter-stem). For Group A, the stem taper was assembled and impacted through the stem. For Group B, the two tapers of the adapter and stem were hand assembled with the mating components and impacted simultaneously through the stem. Assembly load for each construct was recorded. As shown in Figure 1, the constructs were then fixed in a mechanical test frame and an axial distraction force was applied to the end of the stem at a constant displacement rate of 0.075 mm/sec until taper separation or mechanical failure occurred. Force and displacement data were recorded at 50 Hz. Disassembly force was normalized to assembly force for each component. Minitab software was used to analyze the data using a t-test.Objectives
Methods
Total knee replacement (TKR) implant designs and materials have been shown to have a significant impact on tibial insert wear. A medial-pivot (MP) design theoretically should generate less wear due to a large contact area in the medial compartment and lower contact stresses. Synovial fluid aspiration studies have confirmed that a first generation MP TKR system (ADVANCE®, MicroPort Orthopedics Inc., Arlington, TN, USA) generates less wear debris than is seen with other implant designs articulating against conventional polyethylene (CP). The objective of this study was to evaluate the Introduction
Objectives
