Repair of periprosthetic pelvis defects with porous metal implants: a finite element study.

Periacetabular osteolysis is a potentially difficult surgical challenge, which can often drive the choice of reconstruction methods used in revision hip replacement. For smaller defects, impaction of bone grafts may be sufficient, but larger defects can require filler materials that provide structural support in addition to filling a void. This study utilized finite element analysis (FEA) to examine the state of stress in periprosthetic pelvic bone when subjected to a stair-climbing load and in the presence of two simulated defects, to show the effect of implanting a defect repair implant fabricated from Trabecular Metal.

Survivorship of a low-stiffness extensively porous-coated femoral stem at 10 years.

Unlabelled: A novel low-stiffness extensively porous-coated total hip femoral component was designed to achieve stable skeletal fixation, structural durability, and reduced periprosthetic femoral stress shielding. In short- to intermediate-term clinical review, this implant achieved secure biologic fixation and preserved periprosthetic bone. We retrospectively reviewed all 102 prospectively followed patients (106 implants) with this implant to document the longer-term implant survivorship, clinical function, fixation quality, and periprosthetic bone preservation.

In vivo femoral head damage and its effect on polyethylene wear.

The purposes of this study were to determine the spectrum of femoral head damage in patients undergoing revision total hip arthroplasty and to determine the impact of that damage on polyethylene wear. One hundred eight consecutive modular metal femoral heads were retrieved at revision surgery. The mean roughness (Ra) value was 0.

How have new sterilization techniques and new forms of polyethylene influenced wear in total joint replacement?

Polyethylene has undergone many changes over the past several decades, including changes in consolidation processes, resin types, sterilization methods, packaging, and the extent of cross-linking. We believe that new sterilization techniques and forms of polyethylene have generally improved wear performance. Polyethylene sterilized without the use of radiation has been shown to have relatively high rates of wear in vivo.

Characterization of a highly cross-linked ultrahigh molecular-weight polyethylene in clinical use in total hip arthroplasty.

This article reports on a commercially available extensively cross-linked ultrahigh molecular-weight polyethylene (HXPE) produced by subjecting molded GUR 1050 ultrahigh molecular-weight polyethylene (UHMWPE) to 100 +/- 10 kGy of electron beam radiation followed by melt annealing and sterilization by gas plasma. When compared to contemporary conventional molded GUR 1050 UHMWPE sterilized by 37 kGy of gamma radiation, the HXPE material has enhanced wear properties, has no detectable free radicals, and is resistant to oxidation and oxidative-related material property changes. The relative wear improvement of the HXPE is maintained in the presence of bone cement or alumina particles.

Analysis of retrieved acetabular components of three polyethylene types.

The polyethylene used in total hip arthroplasty has gone through many changes over the past several decades, including consolidation processes, resin types, method of sterilization, packaging, and the extent of crosslinking. To isolate the in vivo performance of material changes from implant system design changes, we assessed the postretrieval surface wear and damage of components made from three different polyethylene types used in a single implant system. The polyethylene types investigated are representative of the sequentially available bearing materials that have dominated use in total hip arthroplasty over the last several decades.

The orthopaedic profession and the industry partnership.

The partnership between the orthopaedic profession and industry has existed for more than half a century and has created advanced orthopaedic care and conflicting interest in the delivery of that care. The orthopaedic surgeon first initiated and controlled the relationship with industry as surgeon innovators strove to improve orthopaedic implants. Over time, the practice of orthopaedic surgery and the business of orthopaedic product supply have changed substantially, as has the environment within which each functions.

Clinical performance of contemporary tibial polyethylene components.

A postclinical retrieval analysis was performed on 43 polyethylene tibial components of a contemporary total knee arthroplasty system with implantation duration between 12 and 80 months. Components were scored for 8 potential modes of surface wear or damage on the top and back surfaces. Moderate backside wear of 4.

Changing demographics of patients with total joint replacement.

There has been a substantial change in the population demographics of patients who potentially will require total joint replacements. We studied data regarding temporal trends in physical condition, life expectancy, education, and other population demographics of individuals most likely to receive total joint replacements. Changes in this population during the last several decades correlate with temporal changes in the prevalence of joint disease and the incidence of total hip and knee replacements.

Biomechanics of large femoral heads: what they do and don't do.

The stability and durability of total hip reconstruction is dependent on many factors that include the design and anatomic orientation of prosthetic components. An analysis of femoral component head size and acetabular component orientation shows an interdependency of these variables and joint stability. Increased femoral component head size can increase hip stability by increasing the prosthetic impingement-free range of hip motion and by increasing the inferior head displacement required before hip dislocation.

The role of proximal femoral support in stress development within hip prostheses.

Bone remodeling commonly associated with implant loosening may require revision total hip replacement when there is substantial proximal femoral bone loss. Additionally, the surgical exposure required to remove primary implants may alter the proximal femur's structure. As a result, in many revision hip situations the proximal femur provides compromised support for the revision femoral component.