At ten years, alumina ceramic bearings are functioning well with low complication rates and a fewer number of revisions than the control cohort.

Alumina ceramic bearings have proven superior wear resistance, lubrication, and scratch resistance, without carrying the risk of metal ion release. In 1996 a U.S. IDE clinical trial was initiated utilizing newly improved alumina ceramic materials and implant design. The purpose of this multi-center, prospective, randomized study is to prove comparable safety and efficacy of alumina-alumina ceramic to a control cobalt chrome-polyethylene bearing.

Four hundred fifty two patients (475 hips) are followed in this study. Subjects include ceramic on ceramic, with either porous coated cup or arc deposited cup, or control group with metal on polyethylene with porous coated cup. Average age of subject at time of surgery was 53 years with 82% diagnosis of OA. The average Harris Hip Score was 96 and 94% of hips had little to no pain. Kaplan-Maier survivorship at 10 years, component revision for any reason, was 95.9% for ceramic bearings compared to 91.3% for metal on polyethylene control. There have been nine hips requiring revision of one or both components for any reason.

Data was recently collected on the subjects that participated in either the IDE or Continued Access arms of the ABC^® and Trident^® study. Data collection included revisions, complications, and noise. Out of 930 hips (848 patients) there were nine incidences of squeaking noise reported, no wear/osteolysis issues, and only two insert fractures (0.2%).

At ten years ceramic bearings show no wear, inconsequential lysis, minimal breakage, and occasion noise. Clinically, alumina ceramic bearings perform as well as the metal-on-polyethylene, with fewer revisions and less osteolysis, suggesting that they are a safe, viable option for younger, more active patients.

Acetabular rim damge due to rim impingement is frequently found on retrievals and may be associated with increased wear and contact stresses, instability, and implant loosening of total hip replacement devices. Large X3 bearings (> 36mm) from Stryker have increased implant range of motion and improved polyethylene material (sequentially crosslinked and annealed). A hip simulator wear study was performed with and without femoral neck to acetabular rim impingement to determine the wear performance of these new bearings under aggressive impingement conditions. Two sizes of these new components were tested (36mm with 3.9mm thickness and 40mm with 3.8mm thickness) with two standard sized controls (28mm with 7.9mm thickness in X3 and conventional polyethylene. The 36mm component was chosen to be the largest component utilizing the same shell as the standard 28mm size components while the 40mm component was chosen to be the thinnest bearing currently offered.

Impingement significantly increased wear for all bearings (p< 0.05) but no cracking or failures of the rim occurred. Wear rates for all X3 bearings were statistically indifferent under each testing condition despite bearing size and thickness. Average wear rates for X3 bearings were 0.3mm3/million cycles (mc) under standard conditions and 3.5mm3/mc under impingement conditions. Average wear rates for conventional bearings were 19.5mm3/mc under standard conditions and 48.3mm3/mc under impingement conditions. Overall the X3 bearings exhibited a 93% reduction in wear under impingement conditions and 99% reduction in wear under standard conditions.

Increased bearing range of motion reduces the chance of impingement. This study shows the simulated outcome even if these larger bearings were to impinge. We conclude that these larger X3 bearings exhibits the same wear performance as standard X3 bearings and significantly superior wear performance compared to conventional polyethylene bearings under standard and impingement conditions.

A major challenge for total hip arthroplasty is to minimize wear and osteolysis in young, active patients. Alumina ceramic bearings have shown superior wear resistance and lubrication and do not carry the risk of ion release.

In a prospective randomized study (ABC), 514 hips were implanted. All patients (average age, 53 years) received the same press-fit hydroxyapatite coated femoral stem; two thirds (345 hips) received alumina ceramic bearings, and one third (169 hips) received a cobalt-chrome-on-polyethylene bearing. A fourth arm (Trident) was included involving use of a metal-backed acetabular component implanted in 209 patients.

At a mean follow-up of 35.2 months (range, 24–48 months), there was no significant difference in clinical performance between the patient cohorts. The cohort of patients included in the ABC, Trident, and extended access portion of the study represents a population of 2313 patients with no device related failures attributable to the ceramic on ceramic articulation used in these patients

This new experience involves the use of improved ceramic materials and new design considerations that eliminate the risks and complications of past experiences with ceramic implants and provides a safe bearing option for young patients.

Introduction: Wear simulator studies have predicted that highly cross-linked polyethylenes can reduce linear wear by 50–90% when compared to traditional polyethylene (gamma sterilized in air). Clinical experience with a highly cross-linked polyethylene which was irradiated to 10 megarads and cold anneled but not remelted (Crossfire) began in October 1998.

Methods: 72 Crossfire implants (69 patients) were implanted and have a minimum 3 year follow-up (mean 3.85 years). 31 of these implants (29 patients) have a minimum 4 year follow-up (mean 4.64 years). Linear wear utilizing a validated computerized technique was measured and compared to 38 hips (37 patients) implanted with a non-cross-linked polyethylene (gamma irradiated – N2 vac) with a mean follow-up of 4.96 years.

Results: The mean wear in millimeters per year for the highly cross-linked Crossfire polyethylene with minimum 3 year follow-up was 0.054 (sd=0.032). At minimum 4 year follow-up wear was 0.057 mm/yr (sd=0.036). The wear for the N2 vac non-cross-linked polyethylene was 0.138 mm/yr (sd=0.066). Using a standard t-test the difference in wear was highly significant at p=< 0.001.

Discussion & Conclusion: Cross-linking is the only material characteristic shown to improve wear performance of polyethylene. Our clinical experience demonstrates a 50% reduction in wear over N2 vac irradiated polyethylene during the first three years with no significant change out to a mean of 4.64 years. Cross-linked polyethylenes hold great hopes for significant reduction in wear and osteolysis and prolonged life of hip arthroplasty in patients of all ages.

Today’s major challenge for total hip arthroplasty is to minimise wear and osteolysis in our younger and more active patients. Alumina ceramic bearings have known superior wear resistance and lubrication and do not carry a risk of ion release. Utilising new improved alumina ceramic materials and implant design 514 hips were implanted in a multicentre US IDE prospective and randomised study. The study compared alumina-on-alumina ceramic bearings to a cobalt chrome-on-polyethylene bearing.

All patients received the same press-fit hydroxylapatite coated femoral stem while two-thirds (349 hips) received alumina ceramic bearings and one-third (165 hips) received the cobalt chrome on polyethylene bearing. All patients suffered from non-inflammatory arthritis and were young and active with an average age of 53 years.

At a follow-up of 24–60 months (mean 39.8 months) there was no significant difference in clinical performance between the patient cohorts.

Utilising a new implant design and improved alumina ceramic materials, 514 hips were implanted in a US IDE prospective, randomised study. All patients received the same press-fit hydroxylapatite (HA) coated femoral stem. Two-thirds (349 hips) received alumina ceramic bearings, and one-third (165 hips) received CoCr heads on polyethylene liners. The alumina group was further divided. Approximately one-half (172 hips – System I) received a porous-coated titanium shell and an alumina insert, and one-half (177 hips – System II ) received a HA-coated, arc-deposited titanium shell and an alumina insert. System III (the control) consisted of a porous-coated titanium shell and a polyethylene insert. External geometry of all shells was identical.

An independent orthopaedic surgeon who did not participate in the study reviewed all radiographs. At latest follow-up, (minimum 2 years; range 2-4 years), differences were noted in the developmental pattern of the radiolucent line around the acetabular component. Radiolucent lines were most often noted with System I and System III (porous acetabular shells) in De Lee and Charnley Zone 3 and were absent in System II (arc-deposited titanium with HA) (p=0.001). Other standard radiographic parameters evaluated were found to be comparable, with one exception: In 10 cases in the control group, the development of a small erosive lesion (scalloping) in femoral Gruen Zone 8 was observed on the lateral film. This compares to two cases in System I, and no cases in System II (p=0.001).

Dislocation rates were comparable for all three Systems. Seven acetabular components were revised: one in System I, three in System II and System III. The two revisions for aseptic loosening were both in the control group.