Once Annealed Highly Cross-Linked Polyethylene Exhibits Low Wear at 9 to 15 Years.

A once annealed highly cross-linked polyethylene (HXLPE) was introduced in 1998. Concerns regarding its long-term performance and oxidative resistance exist because of the presence of retained free radicals. The authors studied 48 patients with 50 hip implants having an average age of 62 years.

Second-Generation Annealed Highly Crosslinked Polyethylene has Low Wear at Mean Seven Year Follow-up.

First-generation once annealed highly crosslinked polyethylene (HXLPE) has perfomed well for over 10 years but the presence of free radicals remain a concern. A second-generation sequentially annealed HXLPE was developed to further reduce wear, maintain mechanical strength, and enhance oxidative resistance.

Periprosthetic fractures around a cementless hydroxyapatite-coated implant: a new fracture pattern is described.

Background: Periprosthetic fractures can occur both intraoperatively and postoperatively with implantation of cementless tapered stems.

Questions/purposes: In a large cohort of patients receiving cementless, proximally hydroxyapatite-coated femoral implants, we answered the following questions: What was the incidence of intraoperative and postoperative fractures associated with the implant? What were the fracture patterns as classified by the Vancouver classification system? Did the Vancouver classification represent the fracture patterns found? How were the fractures treated and what were the treatment outcomes; that is, how many fractures healed and did the stems osseointegrate?

Methods: We evaluated 1039 hips (932 patients) from three prospective studies. The hips were divided into three groups: no fractures, intraoperative fractures, and postoperative fractures.

High survivorship with a titanium-encased alumina ceramic bearing for total hip arthroplasty.

Background: Although ceramic-on-ceramic bearings for total hip arthroplasty (THA) show promising results in terms of bearing-surface wear, fracture of the bearing, insertional chips, and squeaking remain a concern.

Questions/purposes: Our primary objective of this report was to determine overall survivorship of a titanium-encased ceramic-on-ceramic bearing couple. Our secondary objectives were to evaluate for ceramic fracture, insertional chips, osteolysis, and device squeaking.

Second-generation annealed highly cross-linked polyethylene exhibits low wear.

Background: Compared with conventional polyethylene, first-generation highly cross-linked polyethylenes have low wear, but controversy exists regarding their reduced mechanical strength and/or retained free radicals. Second-generation highly cross-linked polyethylenes have been developed to reduce wear, maintain mechanical strength, and have oxidative resistance, but it is unclear whether they do so.

Questions/purposes: The primary objective of this study therefore was to determine if a second-generation annealed material has low linear wear at 5 years followup.

Ceramic bearings for total hip arthroplasty have high survivorship at 10 years.

Background: Ceramic bearings were introduced to reduce wear and increase long-term survivorship of total hip arthroplasty. In a previous study comparing ceramic with metal-on-polyethylene at 5 to 8 years, we found higher survivorship and no osteolysis for the ceramic bearings.

Questions/purposes: We asked whether ceramic bearings have equal or superior survivorship compared with that for metal-on-polyethylene at longer followup; we also determined survivorship of the implant systems, the presence or absence of radiographic osteolysis, and incidence of device squeaking.

Continued improved wear with an annealed highly cross-linked polyethylene.

Background: Highly cross-linked polyethylene (HXLPE), created by disrupting the molecular structure of polyethylene, then through the application of heat, encourages creation of new cross-links in the process, resulting in a material with improved wear resistance. The impetuses for this new technology were the unsatisfactory wear properties and subsequent osteolysis of noncross-linked polyethylene. A 72% reduction in wear using highly cross-linked polyethylenes (HXLPE) compared with conventional polyethylene at 5 years was described previously.

Ceramic-on-ceramic hip outcome at a 5- to 10-year interval: has it lived up to its expectations?

This study reports revision and complication rates of a single cementless double-wedged tapered stem with an alumina-alumina bearing over 10 years since the beginning of premarket clinical trials. Of 930 hips (848 patients) implanted by 9 surgeons, there were 19 revisions at mean follow-up of 5.9 years compared to 10 revisions in the 123 hips implanted with the polyethylene control group at mean 7.

Use of an alumina ceramic-on-alumina ceramic bearing surface in THA in a 13 year old with JIA--a single case study.

Total hip arthroplasty (THA) has been shown to be highly effective in ameliorating pain and increasing function in adults with end stage arthritis of the hip. Early studies of cemented THA in children with advanced hip disease reported poor results, but, more recently, results of cementless THA show greatly improved outcomes. More recently, concerns related to THA in children have focused on wear of the bearing surfaces, which may result in periprosthetic bone loss and eventual loosening of the prosthetic components.

Algorithmic approach for reconstruction of proximal femoral bone loss in revision total hip arthroplasty.

Reconstruction of the femur depends on the quantity of bone loss and the quality of the remaining bone stock. Multiple classifications and reporting systems can be used to characterize the bone defect. We present a simple algorithmic approach for proximal femoral bone loss reconstruction during revision total hip arthroplasty.

Trochanteric excision following persistent nonunion of the greater trochanter.

Trochanteric nonunion associated with total hip arthroplasty (THA) may result from 1 of 3 situations: 1) isolated fracture of the greater trochanter; 2) complication of trochanteric osteotomy; or 3) fracture secondary to cystic formation or osteolysis from wear debris post-THA. Isolated fracture of the greater trochanter can occur during primary or revision THA or as a result of trauma in the post-THA patient. It is estimated that approximately 5% of intraoperative femoral fractures involve just the greater trochanter.

Ceramic-on-ceramic total hip arthroplasty: update.

This prospective, randomized, multicenter study of alumina ceramic-on-alumina ceramic bearing couples includes 452 patients (475 hips). Their average age was 53 years with approximately two thirds men and 82% with osteoarthritis. At an average 8-year follow-up, clinical results were excellent and cortical erosions significantly less than in the conventional polyethylene-on-metal bearing group.

Late remodeling around a proximally HA-coated tapered titanium femoral component.

Unlabelled: Most bone remodeling is thought to occur within the first few years after THA. Loss of bone density later may be associated with stress shielding or normal bone loss of aging. We evaluated remodeling changes over time with a proximally hydroxyapatite-coated tapered titanium stem.

Total hip arthroplasty in patients with bone deficiency of the acetabulum.

Total hip replacement (THR) requires revision in only a minority of cases (approximately 17% of prosthetic hips fail), but when THR failures occur there may be significant acetabular bone deficiency. There is a variety of surgical hardware and strategies available to address this problem. The causes of primary THR revision include aseptic loosening or particle disease, infection, recurrent dislocation, implant failure, periprosthetic fracture, and leg length discrepancy.

Provider and center effect in multicenter randomized controlled trials of surgical specialties: an analysis on patient-level data.

Objective: To estimate the importance of center and provider effect and its implication on the estimation of treatment effect in surgical randomized controlled trials.

Summary Background Data: Provider and center effect may play an important role in the estimated treatment effect of multicenter surgical randomized controlled trials (RCTs). However, such effects are rarely accounted for in surgical RCTs.

Long-term outcome of surface replacement with comparison to an age- and time-matched primary total hip arthroplasty cohort.

Surface replacement (SR) was introduced as a bone-conserving alternative to total hip arthroplasty (THA) 3 decades ago, then was abandoned due to polyethylene wear, stress shielding, and loosening. Improved bearing surfaces have renewed interest in SR. This study examined long-term SR outcome compared to an age- and time-matched THA cohort.

Ceramic-on-ceramic total hip arthroplasty early dislocation rate.

Wear debris from metal-on-polyethylene articulation in conventional total hip arthroplasty can limit the implant's longevity. Modern ceramic material with high wear resistance and low fracture risk has the potential to extend the lifetime of total hip arthroplasty, which makes the procedure potentially more suitable for young, active patients. Concerns with brittle ceramic material include fracture risk, the "squeak" phenomenon, and potentially a higher dislocation rate secondary to limited neck lengths and liner options.

Impaction grafting for femoral component revision using a non-polished bead-blasted chrome cobalt stem-average 8 1/2-year follow-up.

Impaction grafting for femoral component revision in patients with significant bone loss has been reported using a tapered polished femoral component that is meant to subside. This study reports our results of femoral component revision using impaction grafting with a bead-blasted chrome cobalt stem designed not to subside. Forty-eight femoral component revisions using impaction grafting were retrospectively reviewed with a minimum 6 1/2-year follow-up.

The basis for a second-generation highly cross-linked UHMWPE.

Highly cross-linked ultra-high molecular weight polyethylene (UHMWPE) decreases wear at the hip by more than 50% compared with conventional UHMWPE. However, melted highly cross-linked polyethylene may be susceptible to fatigue cracking, and annealed highly cross-linked polyethylene may be susceptible to in vivo oxidation. The second-generation highly cross-linked UHMWPE (X3 HXPE) uses a sequential irradiation and annealing process.

Hydroxyapatite-coated femoral components: 15-year minimum followup.

Hydroxyapatite-coated femoral components were introduced to enhance fixation, but concerns were raised about whether the coating would be maintained over time. We therefore determined the long-term clinical and radiographic results of a proximally hydroxyapatite-coated femoral component and compared the mechanical failure rate to other fixation methods at similar lengths of followup. The study group, culled from a large, multicenter prospective study population, consisted of 146 patients (166 hips) with followup of 15 to 18 years.

Multichannel CT Imaging of Orthopedic Hardware and Implants.

The introduction of multichannel CT scanners provides both radiologists and surgeons with a new tool to image patients with orthopedic hardware. The key parameters that have made it possible to image the implants and the surrounding bone with multichannel CT are the higher available technical factors (kVp and mAs) coupled with the ability to acquire thin slices over a large scan region. These properties make it possible to produce high-quality multiplanar reformations that facilitate visualization of the orthopedic device and the surrounding bone.

Arc-deposited hydroxyapatite-coated cups: results at four to seven years.

Unlabelled: A second-generation arc-deposited hydroxyapatite-coated acetabular component was developed after detailed analysis of a failed first-generation grit-blasted hydroxyapatite-coated cup. In our prospective multicenter study we aimed to compare clinical results and survivorship of the newly designed cup to the previous cup and to a similarly designed porous-coated cup during the same time period. The effect of bearing surface-alumina-on-alumina to polyethylene-on-metal-was analyzed.

A titanium-encased alumina ceramic bearing for total hip arthroplasty: 3- to 5-year results.

Unlabelled: We examined whether encasing the alumina ceramic total hip arthroplasty insert in a thin titanium sleeve would reduce significantly or eliminate insert chipping on impaction of the insert into the shell. We also compared results, including observations of osteolysis, of the Trident study group with those of the predecessor alumina bearing couple design to determine clinical improvement and radiographic stability. Beginning in October 1996, 328 alumina ceramic bearings were implanted by six surgeons in 316 patients as a part of a prospective, randomized United States Investigational Device Exemption three-arm study comparing an alumina ceramic bearing with a control bearing of cobalt-chromium on polyethylene.

Five-year experience with Crossfire highly cross-linked polyethylene.

Unlabelled: Our purpose was to compare the clinical wear performance of highly cross-linked (Crossfire) polyethylene with conventional (N2Vac) polyethylene total hip bearings. We implanted 56 hips (47 patients) with Crossfire acetabular bearing liners and compared their wear performance with 53 conventional polyethylene inserts. Wear and clinical data were collected retrospectively at a minimum 4-year and average 5-year followup.