Bone Attachment on a New Design of Cementless Stem and a Widely Used Cup: Postmortem Retrieval Findings.

Case: This was a postmortem retrieval study to assess bone fixation in a hydroxyapatite-coated ACTIS stem and a beaded Pinnacle Sector cup retrieved from an 89-year-old man 15-months postoperatively. Previous radiographic examinations showed good implant fixation without any radiolucency. The sectioned cup and stem showed good fixation on visual, microradiographic, and histological examinations.

Ex vivo regional gene therapy with human adipose-derived stem cells for bone repair.

Background: The treatment of complex bone loss scenarios remains challenging. This study evaluates the efficacy of ex vivo regional gene therapy using transduced human adipose-derived stem cells (ASCs) overexpressing bone morphogenetic protein-2 (BMP-2) to treat critical-sized bone defects.

Methods: Critical-sized femoral defects created surgically in immunocompromised rats were treated with ASCs transduced with a lentivirus encoding BMP-2 (Group 1, n = 14), or green fluorescent protein (Group 2, n = 5), nontransduced ASCs (Group 3, n = 5), or rhBMP-2 (Group 4, n = 14).

Regional gene therapy with 3D printed scaffolds to heal critical sized bone defects in a rat model.

The objective of the present study was to assess the ability of transduced rat bone marrow cells (RBMCs) that overexpress BMP-2 loaded on a three-dimensionally (3D) printed scaffold to heal a critical sized rat femoral defect. Tricalcium phosphate (TCP) scaffolds were 3D printed to fit a critical sized rat femoral defect. The RBMCs were transduced with a lentiviral (LV) vector expressing BMP-2 or GFP.

Contact patch to rim distance: the quintessential tool for metal-on-metal bearing in vivo performance analysis - a review.

With metal-on-metal (MoM) bearings, fluid film lubrication is disrupted when the contact patch area between the femoral head and the cup is close to the edge of the acetabular component, making the calculation of the contact patch to rim (CPR) distance a key variable in the study of the performance of MoM bearings. A few research centers have used models of varying complexity to calculate the CPR distance and determine its relationship with assessments of component wear. In this review, we aimed to summarise the current knowledge related to the application of CPR distance calculations in the study of in vivo performance of MoM bearings.

Do clinical and quality of life scores change over time after hip resurfacing?

Background: Metal-on-metal hip resurfacing (MOMHR) is an alternative to total hip replacement in young and active patients but little is known about the evolution of clinical outcome scores of hip resurfacing over time.The purpose of this study was 1) to assess the long-term evolution of UCLA hip scores and SF-12 Quality of life evaluations in a group of patients treated with hip resurfacing arthroplasty, 2) to determine whether the age of the patient at surgery influenced these outcome measurements, and 3) whether the changes in SF-12 scores are comparable with those of the general US population.

Patient And Methods: A total of 100 patients with unilateral, unrevised, Charnley class A MOMHR were retrospectively selected for the study.

Fixation of non-cemented total hip arthroplasty femoral components in a simulated proximal bone defect model.

An accelerated sequential proximal femoral bone loss model was used to measure the initial stability of three noncemented femoral stem designs: fully porous-coated, proximally porous-coated, and dual-tapered, diaphyseal press-fit (N=18). Only dual-tapered, diaphyseal press-fit stems remained stable with as much as 105 mm of bone loss, with average cyclic micromotion remaining below 25 μm in ML and below 10 μm in AP planes. In contrast, with proximally coated and fully coated stem designs with circular or oval cross-sections, 60mm of bone loss, resulting in lower than 10 cm of diaphyseal bone contact length, led to gross instability, increasing average cyclic micromotions to greater than 100 μm prior to failure.

Material and surface factors influencing backside fretting wear in total knee replacement tibial components.

Retrieval studies have shown that the interface between the ultra-high molecular weight polyethylene insert and metal tibial tray of fixed-bearing total knee replacement components can be a source of substantial amounts of wear debris due to fretting micromotion. We assessed fretting wear of polyethylene against metal as a function of metal surface finish, alloy, and micromotion amplitude, using a three-station pin-on-disc fretting wear simulator. Overall, the greatest reduction in polyethylene wear was achieved by highly polishing the metal surface.

Wear of an experimental metal-on-metal artificial disc for the lumbar spine.

Study Design: In vitro wear simulation.

Objective: To determine the type and amount of wear produced by experimental metal-on-metal artificial discs for the lumbar spine. To minimize the amount of wear by changing the carbon content, clearance, and presence of a keel and notch.

Fibroblast growth factor-2 alters the effect of eroding polylactide-polyglycolide on angiogenesis in the bone chamber.

The effects of recombinant human fibroblast growth factor-2 in the presence of eroding 50:50 poly(DL-lactide-co-glycolide) on angiogenesis during acute bone defect healing were studied in the optical bone chamber. Bone chambers were loaded with disks of poly(DL-lactide-co-glycolide) surrounded by one of four doses of recombinant human fibroblast growth factor-2. Fifty-two female rabbit right tibias were implanted.

Comparative bone healing near eroding polylactide-polyglycolide implants of differing crystallinity in rabbit tibial bone chambers.

Eroding poly(DL-lactide-co-glycolide) (PDLLG) washers and poly(L-lactide-co-glycolide) (PLLG) threads were observed chronically in vivo following loading in a bone chamber tibial implant (BCI). Images were recorded using intravital microscopy of the implanted rabbit. Erosion and bone healing, as represented by angiogenesis and osteogenesis, was determined from changes in projected area of observed polymer, vessels and bone, respectively.