Acetabular bone loss during revision total hip arthroplasty (THA) poses a challenge for reconstruction as segmental and extensive cavitary defects require structural support to achieve prosthesis stability. Trabecular metal (TM) acetabular augments structurally support hemispherical cups. Positive short-term results have been encouraging, but mid- to long-term results are largely unknown. The purpose of this study was to determine the continued efficacy of TM augments in THA revisions with significant pelvic bone loss. Radiographs and medical records of 51 patients who had undergone THA revision with the use of a TM augment were retrospectively reviewed. Acetabular defects were graded according to the Paprosky classification of acetabular deficiencies based on preoperative radiographs and operative findings. Loosening was defined radiographically as a gross change in cup position, change in the abduction angle (>5°), or change in the vertical position of the acetabular component (>8 mm) between initial postoperative and most recent follow-up radiographs (Figure 1).Purpose:
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Although short term outcomes of reverse total shoulder arthroplasty (rTSA) have been promising, long-term success may be limited due to complications, including scapular notching. Scapular notching has been explained primarily as a mechanical erosion, however, generation of wear debris may lead to further biologic changes contributing to the severity of scapular notching. Highly cross-linked ultra-high molecular weight polyethylene (UHMWPE) has been used routinely in constrained joint applications such as total hip arthroplasty for reduction of wear debris particles. Although rTSA shares similarity in design conformity, conventional UHMWPE remains the gold standard. A commercially available hip simulator was converted to a 12-station rTSA wear simulator. Conventional and highly cross-linked UHMWPE humeral liners were subjected to 5,000,000 cycles of alternating abduction-adduction and flexion-extension loading profiles. Every 250,000 cycles, liners were evaluated with gravimetric wear measurements and test serum was collected for morphological characterization of wear particles.Purpose:
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The optimal degree of conformity between the glenoid and humeral components in cemented total shoulder arthroplasty (TSA) has not been established. Glenoid component stability is thought to be at risk due to the “rocking-horse” phenomenom, which, can lead to increased micromotion and loosening in response to humeral head edge loading. The goal of this biomechanical study is to investigate the influence of glenohumeral mismatch on bone-implant interface micromotion in a cemented glenoid implant model. Twenty-Five cemented glenoid components (Affiniti, Tornier, Inc., Bloomington, MN, USA) were implanted in polyurethane foam biomechanics testing blocks. Five glenoid sizes, 40 mm, 44 mm, 48 mm, 52 mm and 55 mm (n = 5 per glenoid size), were cyclically tested according to ASTM Standard F-2028-08. A 44 mm humeral head (Affiniti, Tornier, Inc., Bloomington, MN, USA) was positioned centrally within the glenoid fixed to a materials testing frame (MTS Mini-Bionix II, Eden Prairie, MN, USA). Phase I testing (n = 3 per glenoid size) involved a subluxation test for determination of the humeral head translation distance which would be used for phase II cyclic testing. During cyclic loading, the humeral head was translated ± distance for 50,000 cycles at a frequency of 2 Hz, simulating approximately 5 years of device use. Glenoid compression, distraction, and superior-inferior glenoid translation were measured throughout testing via two differential variable reluctance transducers.Purpose:
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Unicompartmental knee arthroplasty (UKA) has been used in the past decades to treat progressive cartilage degeneration in a single compartment. Concern has been raised over the rate of revision procedures for polyethylene wear and osteoarthritic progression into the adjacent compartment. Few studies have examined the pathology of cartilage degeneration in the setting of UKA. This study aims to investigate the viability of knee chondrocytes introduced to high and low concentrations of orthopaedic wear debris particulate. Normal human articular chondrocytes (nHAC-Kn) were expanded in DMEM/F12 containing 10% FBS, 1% Penicillin/Streptomycin (Pen/Strp), and 50 μg/mL ascorbic acid (Asc). 24 hours prior to the start of the experiment, cells were seeded on 96-well plates at a density of 3500 cells/cm2 and exposed to DMEM/F12 containing 5% FBS, 1% Pen/Strp, and 50 μg/mL Asc. Particles (equivalent circle diameter range: 0.2–7 μm) at a low dose of 100: 1 (particles: cells) and high dose 1000: 1 (particles: cells) were introduced to treatment wells (n = 6). Control wells (n = 6) contained particles with no cells. Treatment groups included high and low doses of TiAl6V4 alloy, 316L Stainless Steel, and Co-Cr-Mo alloy. At days 1, 3, 5, and 7, cells were assayed with a 3-(4,5-Dimethylthiazol-2-yl)-2,5-dyphenyltetrazolium bromide (MTT) assay for determination of cell viability. Light microscopy was performed at each timepoint to assess change in cell morphology.Introduction:
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Glenoid loosening persists as a common cause of anatomic total shoulder arthroplasty (TSA) failure. Considering radiographic evidence of loosening as an endpoint, TSA has a reported survivorship of only 51.5% at 10 years. Component loosening may be related to cementation and it is postulated that poor cement penetration and heat-induced necrosis may partially be responsible. There is a growing interest among surgeons to minimize or abandon cement fixation and rely on biologic fixation to the polyethylene for long-term fixation. De Wilde et al. reported promising early clinical and radiographic results using a pegged, all-polyethylene ingrowth glenoid design implanted without cement. The goal of this study was to compare glenoid micromotion in an all-polyethylene, centrally fluted pegged glenoid using 3 cement fixation techniques. Glenoid components (Anchor Peg Glenoid, Depuy Orthopaedics, Warsaw, IN, USA) (Figure 1) were implanted in polyurethane foam testing blocks with 3 different fixation methods (n = 5 per group). Group I glenoids were implanted with interference fit fixation with no added cement. Group II was implanted with a hybrid fixation, where only the peripheral pegs were cemented. Group III glenoids were fully cemented for implantation. Glenoid loosening was characterized according to ASTM Standard F-2028. The glenoid component and a 44 mm humeral head were mounted to a materials testing frame (858 Mini Bionix II, MTS Crop., Eden Prairie, MN, USA) with a 750N applied joint compressive force (Figure 1). A humeral head subluxation displacement of ± 0.5 mm was experimentally calculated as a value that simulates glenoid rim loading that may occur at higher load activities. For characterization of glenoid loosening, the humeral head was cycled 50,000 times along the superior-inferior glenoid axis, simulating approximately 5 years of device service. Glenoid distraction, compression, and superior-inferior glenoid migration were recorded with two differential variable reluctance transducers fixed to the glenoid prosthesis.Purpose:
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