Reverse hybrid and cemented hip replacement compared using radiostereometry and dual-energy X-ray absorptiometry: 43 hips followed for 2 years in a prospective trial.

BACKGROUND AND PURPOSE: Total hip replacement (THR) with a reverse hybrid (RH), a combination of a cemented polyethylene cup and a cementless femoral stem, has been increasingly used in Scandinavia. In a randomized trial, we compared an RH THR with a proximal hydroxyapatite- (HA-) coated stem to a conventional cemented THR. Both groups received the same polyethylene cup. PATIENTS AND METHODS: 51 patients (52 hips) were included. Radiostereometry (RSA) and dual-energy X-ray absorptiometry (DEXA) were performed postoperatively and after 6, 12, and 24 months. 42 patients (43 hips) were followed for 2 years. RESULTS: Mean cup rotation around the x-axis was 0.13° for the cemented group and -0.24° for the RH group (p = 0.03). Cup migration in the other axes, and stem migration and wear were similar between the 2 study groups. Bone remodeling around the cup was also similar between the groups. Bone loss in Gruen zone 1 was 18% for the cementless stems, as compared to an increase of 1.4% for the cemented ones (p < 0.001). Bone loss was similar in the other Gruen zones. Harris hip score and Oxford hip score were similar pre- and postoperatively in the 2 groups. INTERPRETATION: In the present study, RH THR with a cementless hydroxyapatite-coated stem and conventional cemented THR did not show any major differences regarding stem migration and bone loss after 2 years of follow-up.

Is reverse hybrid hip replacement the solution?

BACKGROUND AND PURPOSE: Reverse hybrid hip replacement uses a cemented all-polyethylene cup and an uncemented stem. Despite increasing use of this method in Scandinavia, there has been very little documentation of results. We have therefore analyzed the results from the Norwegian Arthroplasty Register (NAR), with up to 10 years of follow-up. PATIENTS AND METHODS: The NAR has been collecting data on total hip replacement (THR) since 1987. Reverse hybrid hip replacements were used mainly from 2000. We extracted data on reverse hybrid THR from this year onward until December 31, 2009, and compared the results with those from cemented implants over the same period. Specific cup/stem combinations involving 100 cases or more were selected. In addition, only combinations that were taken into use in 2005 or earlier were included. 3,963 operations in 3,630 patients were included. We used the Kaplan-Meier method and Cox regression analysis for estimation of prosthesis survival and relative risk of revision. The main endpoint was revision for any cause, but we also performed specific analyses on different reasons for revision. RESULTS: We found equal survival to that from cemented THR at 5 years (cemented: 97.0% (95% CI: 96.8-97.2); reverse hybrid: 96.7% (96.0-97.4)) and at 7 years (cemented: 96.0% (95.7-96.2); reverse hybrid: 95.6% (94.4-96.7)). Adjusted relative risk of revision of the reverse hybrids was 1.1 (0.9-1.4). In patients under 60 years of age, we found similar survival of the 2 groups at 5 and 7 years, with an adjusted relative risk of revision of reverse hybrids of 0.9 (0.6-1.3) compared to cemented implants. INTERPRETATION: With a follow-up of up to 10 years, reverse hybrid THRs performed well, and similarly to all-cemented THRs from the same time period. The reverse hybrid method might therefore be an alternative to all-cemented THR. Longer follow-up time is needed to evaluate whether reverse hybrid hip replacement has any advantages over all-cemented THR.

Antibiotic-Loaded Bone Cement in Prevention of Periprosthetic Joint Infections in Primary Total Knee Arthroplasty: A Register-based Multicentre Randomised Controlled Non-inferiority Trial (ALBA trial).

INTRODUCTION: The current evidence on the efficacy of antibiotic-loaded bone cement (ALBC) in reducing the risk of periprosthetic joint infections (PJI) after primary joint reconstruction is insufficient. In several European countries, the use of ALBC is routine practice unlike in the USA where ALBC use is not approved in low-risk patients. Therefore, we designed a double-blinded pragmatic multicentre register-based randomised controlled non-inferiority trial to investigate the effects of ALBC compared with plain bone cement in primary total knee arthroplasty (TKA). METHODS AND ANALYSIS: A minimum of 9,172 patients undergoing full-cemented primary TKA will be recruited and equally randomised into the ALBC group and the plain bone cement group. This trial will be conducted in Norwegian hospitals that routinely perform cemented primary TKA. The primary outcome will be risk of revision surgery due to PJI at 1-year of follow-up. Secondary outcomes will be: risk of revision due to any reason including aseptic loosening at 1, 6, 10 and 20 years of follow-up; patient-related outcome measures like function, pain, satisfaction and health-related quality of life at 1, 6 and 10 years of follow-up; risk of changes in the microbial pattern and resistance profiles of organisms cultured in subsequent revisions at 1, 6, 10 and 20 years of follow-up; cost-effectiveness of routine ALBC versus plain bone cement use in primary TKA. We will use 1:1 randomisation with random permuted blocks and stratify by participating hospitals to randomise patients to receive ALBC or plain bone cement. Inclusion, randomisation and follow-up will be through the Norwegian Arthroplasty Register. ETHICS AND DISSEMINATION: The trial was approved by the Western Norway Regional Committees on Medical and Health Research Ethics (reference number: 2019/751/REK vest) on 21 June 2019. The findings of this trial will be disseminated through peer-reviewed publications and conference presentations. TRIAL REGISTRATION NUMBER: NCT04135170.

Distinct Subsets of Noncoding RNAs Are Strongly Associated With BMD and Fracture, Studied in Weight-Bearing and Non-Weight-Bearing Human Bone.

We investigated mechanisms resulting in low bone mineral density (BMD) and susceptibility to fracture by comparing noncoding RNAs (ncRNAs) in biopsies of non-weight-bearing (NWB) iliac (n = 84) and weight bearing (WB) femoral (n = 18) postmenopausal bone across BMDs varying from normal (T-score > -1.0) to osteoporotic (T-score ≤ -2.5). Global bone ncRNA concentrations were determined by PCR and microchip analyses. Association with BMD or fracture, adjusted by age and body mass index, were calculated using linear and logistic regression and least absolute shrinkage and selection operator (Lasso) analysis. At 10% false discovery rate (FDR), 75 iliac bone ncRNAs and 94 femoral bone ncRNAs were associated with total hip BMD. Eight of the ncRNAs were common for the two sites, but five of them (miR-484, miR-328-3p, miR-27a-5p, miR-28-3p, and miR-409-3p) correlated positively to BMD in femoral bone, but negatively in iliac bone. Of predicted pathways recognized in bone metabolism, ECM-receptor interaction and proteoglycans in cancer emerged at both sites, whereas fatty acid metabolism and focal adhesion were only identified in iliac bone. Lasso analysis and cross-validations identified sets of nine bone ncRNAs correlating strongly with adjusted total hip BMD in both femoral and iliac bone. Twenty-eight iliac ncRNAs were associated with risk of fracture (FDR < 0.1). The small nucleolar RNAs, RNU44 and RNU48, have a function in stabilization of ribosomal RNAs (rRNAs), and their association with fracture and BMD suggest that aberrant processing of rRNAs may be involved in development of osteoporosis. Cis-eQTL (expressed quantitative trait loci) analysis of the iliac bone biopsies identified two loci associated with microRNAs (miRNAs), one previously identified in a heel-BMD genomewide association study (GWAS). In this comprehensive investigation of the skeletal genetic background in postmenopausal women, we identified functional bone ncRNAs associated to fracture and BMD, representing distinct subsets in WB and NWB skeletal sites. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Low wear rate at 6-year follow-up of vitamin E-infused cross-linked polyethylene: a randomised trial using 32- and 36-mm heads.

BACKGROUND: Free radicals formed in the cross-linking process may over time alter the mechanical properties of highly cross-linked polyethylene. Vitamin E-infused highly cross-linked polyethylene was therefore developed to achieve low wear-rate and good mechanical properties in the long term. AIM: To present 6-year results from the initial randomised controlled trial. PATIENTS AND METHODS: We measured wear and periacetabular bone remodelling in cementless total hip arthroplasty; 32- or 36-mm Biolox Delta heads and vitamin E-infused highly cross-linked polyethylene (E-Poly) were used. Markerless radiosterometric analysis measured the in vivo wear and dual energy x-ray absorptiometry was used to analyse bone remodelling in 40 hips at 6-year follow-up. RESULTS: In the proximal direction the wear for 32- and 36-mm heads was 0.15 mm (95% confidence interval [CI], 0.08-0.21) and 0.06 mm (95% CI, -0.002-0.12), respectively (p = 0. 015). However, between 3 months and 6 years (excluding the period of "bedding in"), the proximal wear for 32- and 36-mm heads was 0.10 mm (95% CI, 0.05-0.15) and 0.05 mm (95% CI, -0.01-0.11), respectively (p = 0.12). The annual proximal wear rate for 32- and 36-mm heads from 3 months to 6 years was 0.02 mm and 0.01 mm, respectively. There was no difference in bone remodelling around the cup from baseline to 6 years for the total material and no differences between study groups. CONCLUSION: Wear of this vitamin E-infused highly cross-linked polyethylene is still low at 6-year follow-up, with no significant difference in wear from 3 months to 6 years between 32- and 36-mm heads.

E-vitamin infused highly cross-linked polyethylene: RSA results from a randomised controlled trial using 32 mm and 36 mm ceramic heads.

BACKGROUND: Polyethylene wear has been a major cause of revision of cementless total hip replacements. Highly cross-linked polyethylene has been developed to increase mechanical resistance to wear. However, cross-linking from irradiation of the polyethylene generates free radicals and these can oxidise in vivo and might over time alter the initial mechanical properties. Vitamin-E infused highly cross-linked polyethylene has been developed to reduce the amount of free radicals without compromising the mechanical properties. PURPOSE: To measure wear of vitamin E infused highly cross-linked polyethylene and compare wear between 2 different head sizes. METHODS: In a prospective randomised study between 32 mm and 36 mm Biolox® delta heads in 50 hips we analysed the in vivo wear of the E-poly™ with markerless radiostereometry. RESULTS: Mean (95% CI) wear for the total material was 0.041 mm (0.015-0.066) in the vertical direction and 0.177 mm (0.155-0.200) in the total 3D direction. After the anticipated period of bedding-in we found no statistically significant differences in wear from three months to 2 years in vertical and total 3D directions. Although statistical significant differences between 32 mm and 36 mm heads were found in the total 3D direction we cannot conclude that there are significant clinical important differences in wear comparing these head sizes. CONCLUSIONS: This study shows promising early results with very low wear, even for 36 mm heads, but long term follow-up is necessary to evaluate if this polyethylene will provide low wear and good mechanical properties in the long-term.

Segment choice and cup stability influence wear measurements using radiostereometric analysis: a radiostereometric study comparing wear measured by markers in the polyethylene with markers in the periacetabular bone.

BACKGROUND: Radiostereometry is a well documented method to measure the polyethylene wear after total hip replacements. Wear is measured according to the point motion of the head center in relation to the polyethylene as the reference segment. Increasing head sizes and new cup materials may diminish visibility of markers deteriorating the segment and leading to study drop outs. Alternatively markers in the periacetabular bone may be easier to detect rendering this segment more stable. Our aim was to compare wear measurements against the cup, the acetabuluar bone and a calculated wear estimation including cup migration. METHODS: A prospective randomized controlled trial comparing reverse hybrid with cemented total hip replacement was conducted. 31 patients had tantalum markers in the polyethylene and in the periacetabular bone making it possible to measure wear using both as reference segments. We used a uniplanar radiostereometric technique. FINDINGS: Wear in the y-axis was overestimated by 53% when markers in the periacetabular bone were used (P<0.001). Proximal wear was 0.34 mm (95% CI of mean: 0.29-0.38) when using the polyethylene as the reference and 0.52 mm (95% CI of mean: 0.38-0.65) using the acetabular bone. Migration of the cup seemed to influence the wear calculations, overestimating wear when markers in the periacetabular bone were used as the reference segment. INTERPRETATION: Wear measured with periacatebular bone markers is influenced by cup migration, overestimating wear measurements. We therefore recommend not using the acetabular bone as the reference segment.