A prospective randomised study of periprosthetic femoral bone remodeling using four different bearings in hybrid total hip arthroplasty

Comparison between ceramic-on-polyethylene versus metal-on-polyethylene prostheses in Total Hip Arthroplasties: a systematic review and meta-analysis

The Guidelines Project, an initiative of the Brazilian Medical Association, aims to combine information from the medical field to standardize how to conduct, and to assist in the reasoning and decision-making of doctors. The information provided by this project must be critically evaluated by the physician responsible for the conduct that will be adopted, depending on the conditions and the clinical condition of each patient.

An Isoelastic Monoblock Cup Retains More Acetabular and Femoral Bone Than a Modular Press-Fit Cup: A Prospective Randomized Controlled Trial

BACKGROUND

For cup revision after total hip arthroplasty, sufficiently good periacetabular bone stock is a prerequisite for fixation of the revision implant. Cementless cups can lead to a relevant reduction of peri-implant bone mineral density (BMD) through stress-shielding.

METHODS

Fifty patients were included in this prospective randomized controlled trial. Group 1 (RM group) received an isoelastic monoblock cup (RM Pressfit vitamys; Mathys). Group 2 (IT group) received a modular titanium cup (Allofit-S IT Alloclassic with a polyethylene liner; Zimmer). Periacetabular BMD was determined and subdivided into 4 regions of interest by dual x-ray absorptiometry at 1 week (baseline) and at 4 years postoperatively. Our primary outcome was reduction in periacetabular BMD.

RESULTS

Periacetabular BMD was reduced by an average of 15.1% in the RM group and 16.5% in the IT group at 4 years postoperatively. No significant difference was found between the 2 groups over the periacetabular structure as a whole. However, the decrease of BMD in the polar region was significantly different in the RM group (4.9% ± 10.0%) compared with the IT group (15.9% ± 14.9%, p = 0.005). Use of the isoelastic RM cup showed significantly less bone loss than the modular IT cup.

CONCLUSIONS

Relevant loss of BMD at 4 years after surgery was identified in the periacetabular region in both groups. No differences between the 2 cup systems were found when looking at the overall periacetabular region. As a secondary outcome, less postoperative periacetabular bone loss occurred in the polar region when an isoelastic cup was used. Longer follow-up is required to allow for conclusions to be drawn about the long-term course of the 2 cup systems.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Long-term follow-up of bone remodelling after cementless hip arthroplasty using different stems

The present paper is concerned with the investigation of the phenomenon of long-term bone remodelling on cementless hip replacements. Changes in bone density in the periprosthetic region around the stem, measured by dual X–ray absorptiometry (DXA), were used as a measure of the osseous adaptation reaction. A postoperative follow-up of the use of four different types of prostheses of varying design after on average 13.3 (11.4–14.5) years. Specifically, the prostheses assessed in this study were the CLS/Spotorno stem with the Allofit cup by Zimmer, the Vision 2000 stem with the Duraloc cup by DePuy Synthes, the AlphaFit stem with the AlphaLock cup by Corin and the Mayo stem with the Trilogy cup by Zimmer. For the DXA measurement, the femur was divided into the zones suggested by Gruen et al. On the femur, there was a significant reduction in bone mineral density (BMD) in the proximal Region Of Interest (ROI) 1 (p = 0.003) and 7 (p < 0.001), whilst there was a significant increase in ROI 4 (p = 0.03). A greater degree of bone atrophy was seen in patients aged 60 years and older and in female patients. A remarkable finding when comparing the stems was a significantly greater reduction in BMD in ROI 6 (p = 0.003) in the case of the Vision 2000 stem and a markedly, but not statistically significantly smaller reduction in BMD in ROI 7 (p = 0.18) in the case of the short-stem Mayo-type prosthesis. The best clinical results were found with the use of the latter. The investigations provide a starting point for establishing a differential indication in the choice of prosthesis types, depending on age and sex, the use of short-stem prostheses, as well as the administration of bone-effective drugs for the prevention of stress shielding.

A randomised, controlled clinical study on total hip arthroplasty using 4 different bearings: results after 10 years

PURPOSE

To compare 4 different bearings in total hip arthroplasty (THA) in a randomised controlled clinical study on clinical performance.

METHODS

393 patients with osteoarthritis of the hip or avascular necrosis were included and allocated to 1 of the head-and-cup couples zirconia-on-polyethylene (group A), metal-on-metal (group B), zirconia-on-polyethylene with the liner moulded into the shell (group C), or alumina-on-alumina (group D). In the individual case the surgeon could choose other implants if indicated.

RESULTS

299 patients were operated with the allocated prosthesis. The estimated cumulated prosthesis survival percentages and 95% confidence interval after 10 years were: group A 84.6 (75.8-93.4); group B 95.0 (89.5-100); group C 93.2 (86.7-99.7); group D 66.1 (54.5-77.7). The patients' physical function was significantly improved and remained equally good in all 4 groups, however slightly declining with ageing. The luxation rate was initially high, and equal between the groups, but was reduced by improving the surgical procedure introducing capsule repair by reinsertion of the short external hip rotators.

CONCLUSIONS

The metal-on-metal or zirconia-on-polyethylene prostheses had high 10-year survival percentages. The longevity of these bearing couples by themselves was not related to the combination of materials. The zirconia-on-polyethylene prosthesis with the liner mounted peroperatively possibly exhibited cases of backside wear which the corresponding bearing couple with moulded polyethylene (Asian) did not. The alumina-on-alumina bearing performed poorly - it was redesigned after our study initiation and later withdrawn from the market.

Increased Mortality in Metal-on-Metal versus Non-Metal-on-Metal Primary Total Hip Arthroplasty at 10 Years and Longer Follow-Up: A Systematic Review and Meta-Analysis

IMPORTANCE

There are concerns about increased mortality in patients with metal-on-metal bearings in total hip arthroplasty (THA).

OBJECTIVE

To determine the mortality and the morbidity in patients with metal-on-metal articulations (MOM THA) compared to patients with non-metal-on-metal articulations (non-MOM THA) after primary total hip arthroplasty.

DATA SOURCES

Search of PubMed, MEDLINE, EMBASE, Web of Science, Cochrane, CINAHL, AcademicSearchPremier, ScienceDirect, Wiley and clinical trial registers through March 2015, augmented by a hand search of references from the included articles. No language restrictions were applied.

STUDY SELECTION

Two reviewers screened and identified randomised controlled trials and observational studies of primary total hip arthroplasty comparing MOM THA with non-MOM THA.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted study data and assessed risk of bias. Risk differences (RD) were calculated with random effect models. Meta-regression was used to explore modifying factors.

MAIN OUTCOMES AND MEASURES

Difference in mortality and difference in morbidity expressed as revisions and medical complications between patients with MOM THA and non-MOM THA.

RESULTS

Forty-seven studies were included, comprising 4,000 THA in randomised trials and over 500,000 THA in observational studies. For mortality, random effects analysis revealed a higher pooled RD of 0.7%, 95%, confidence interval (CI) [0.0%, 2.3%], I-square 42%; the heterogeneity was explained by differences in follow-up. When restricted to studies with long term follow-up (i.e. 10 years or more), the RD for mortality was 8.5%, 95%, CI [5.8%, 11.2%]; number needed to treat was 12. Further subgroup analyses and meta-regression random effects models revealed no evidence for other moderator variables (study level covariates, e.g. resurfacing vs. non-resurfacing MOM) than follow-up duration. The quality of the evidence presented in this meta-analysis was characterized as moderate according to the CLEAR-NPT (for non-pharmacological trials) and Cochrane risk of bias Table.

CONCLUSIONS AND RELEVANCE

Meta-analysis suggests there may be an increased long-term risk of mortality and revision surgery for patients with MOM THA compared to patients with non-MOM THA.

REGISTRATION

PROSPERO 2014:CRD42014007417.

Effect of bone type on clinical and radiographic outcomes of a proximally-coated cementless stem in primary total hip arthroplasties

We determined the effect of pre-operative bone structure upon the temporal effects of remodeling after total hip arthroplasty (THA) in a series of uncemented implants. We evaluated 345 patients (375 hips), who had either Dorr Type-A (238 hips) or Type-B (137 hips) bone, and who received a proximally-coated cementless THA and were followed for a mean of 6 years. Outcomes evaluated included aseptic survivorship, Harris hip scores, and radiographic evaluation for patterns of remodeling. The aseptic survivorship (97.5% vs. 98%) and the mean final Harris hip scores (92 vs. 94 points) were similar between Types-A and -B bone, respectively. Bone remodeling was seen significantly earlier and over a longer duration for patients who had Type-B bone. At 5-years, periprosthetic condensation (78% vs. 54%) and cortical hypertrophy (53% vs. 37%) were significantly higher and radiolucencies at any zone were lower (53% vs. 37%) in Type-B compared to Type-A bone. There was increased condensation in men and higher cortical hypertrophy in women. Various radiographic remodeling differences may not negatively impact clinical outcome at mid-term follow-up. Morphologic bone type appears to be predictive of physiologic response to loading.