No difference in migration or wear between cemented low-profile cups and standard cups : A randomized radiostereographic study of 53 patients over 3 years

Background?Minor design changes may cause major changes in implant performance. Thus, as part of a stepwise introduction of a new low-profile cup, we performed a randomized trial comparing it to a well-docu-mented standard cup.

Patients and methods?60 patients, stratified according to sex, weight, and age, underwent cemented total hip arthroplasty using a Lubinus SP2 stem with ceramic head and were randomized to either the new low-profile Lubinus Flanged Anti-Luxation cup (FAL) or the Lubinus Standard Eccentric cup (Standard). 7 patients were excluded and 53 (28 FAL) were evaluated at 3, 6, 12, and 36 months postoperatively. Primary outcome variables, cup migration (MTPM), and wear (total 3-dimensional femoral head penetration) were measured with radiostereometry (RSA). Clinical outcome was evaluated with the western Ontario and McMaster osteoarthritis index (Womac) and the visual analog pain score (VAS).

Results?We found no difference in migration between the FAL and Standard cups. There was no difference in wear between the two cups and there was no correlation between wear and migration. 3 cups (2 FAL and 1 Standard) showed continuous migration of a magnitude that indicated an increased risk of early loosening. Clinical outcome was excellent, without any difference between the 2 groups.     

No differences in outcomes between cemented and uncemented acetabular components after 12–14 years: results from a randomized controlled trial comparing Duraloc with Charnley cups

Background  

Even though there are multiple studies documenting the outcome of the Charnley low-friction arthroplasty as well as abundant studies on uncemented arthroplasties, there is a dearth of comparative studies of the uncemented acetabular component and a cemented component. In this study we aimed to document the long-term clinical and radiographic outcome as well as component survival in a randomized controlled trial.     

Wear and migration of highly cross‐linked and conventional cemented polyethylene cups with cobalt chrome or Oxinium femoral heads: A randomized radiostereometric study of 150 patients

This randomized study was performed to compare wear and migration of five different cemented total hip joint articulations in 150 patients. The patients received either a Charnley femoral stem with a 22.2 mm head or a Spectron EF femoral stem with a 28 mm head. The Charnley articulated with a γ‐sterilized Charnley Ogee acetabular cup. The Spectron EF was used with either EtO‐sterilized non‐cross‐linked polyethylene (Reflection All‐Poly) or highly cross‐linked (Reflection All‐Poly XLPE) cups, combined with either cobalt chrome (CoCr) or Oxinium femoral heads. The patients were followed with repeated RSA measurements for 2 years. After 2 years, the EtO‐sterilized non‐cross‐linked Reflection All‐Poly cups had more than four times higher proximal penetration than its highly cross‐linked counterpart. Use of Oxinium femoral heads did not affect penetration at 2 years compared to heads made of CoCr. Further follow‐up is needed to evaluate the benefits, if any, of Oxinium femoral heads in the clinical setting. The Charnley Ogee was not outperformed by the more recently introduced implants in our study. We conclude that this prostheses still represents a standard against which new implants can be measured. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29: 1222–1229, 2011     

Direct comparison of polyethylene wear in cemented and uncemented acetabular cups

Background  

It has been indicated that, in the long term, the rate of wear and the degree of osteolysis observed with uncemented acetabular components are greater than those associated with cemented cups, but most studies which compare the wear characteristics of cementless with cemented cups have used historical controls. We report a direct comparison of wear of a cemented and an uncemented cup with similar design, polyethylene, and sterilization method.     

In vivo wear and migration of highly cross-linked polyethylene cups a radiostereometry analysis study

In 50 cemented hip arthroplasties, wear and migration of the polyethylene (PE) cups were measured with radiostereometric analysis for a period of 2 years. Twenty had a normal gamma-in-air-sterilized PE, another 20 had a PE sterilized with 30000 Gy followed by heat stabilization (Duration; Stryker Orthopaedics, Mahwah, NJ), and 10 had highly cross-linked PE cups irradiated with 100000 Gy (Crossfire; Stryker Orthopaedics). In the initial 2 months, head penetration (creep) was 63 microm on average for the 3 groups. From 2 to 24 months, the mean proximal head penetration (wear) was 156 microm for standard PE, 138 microm for stabilized PE (P = .45), and 23 microm for highly cross-linked PE (P < .001; analysis of variance). The low in vivo wear rate for highly cross-linked cups was not at the expense of higher migration or less favorable clinical outcome and looks promising.     

No difference between daily and weekly pin site care: a randomized study of 50 patients with external fixation

INTRODUCTION: We investigated whether there were any differences in the frequency and severity of pin site infections by performing pin site care daily or once a week. We studied patients operated on for gonarthrosis by the hemicallotasis technique, using hydroxyapatite-coated pins in the metaphyseal bone and standard pins in the diaphyseal bone. PATIENTS AND METHODS: 50 patients were prospectively randomized to daily (n = 27) or weekly (n = 23) pin site care. We evaluated pin sites, the occurrence of pain (VAS), the use of antibiotics and analgesics and complications every week. Bacterial cultures were taken from each pin site at 1, 6 and 10 weeks and from the pins on removal. RESULTS: We found no differences between daily or weekly pin site care as regards the frequency and severity of pin site infections, pain, or the use of antibiotics and analgesics. Grade I infections (Checketts-Otterburns classification) occurred around 11% of the pins and grade II infections around 4%. 70% of the bacterial cultures were negative. The most frequent bacteria were coagulase negative staphylococcus and corynebacterium. Antibiotics were given an average of 47 days. More problems occurred around the proximal pins. 5/200 (all proximal) pins were clinically loose on removal. INTERPRETATION: Pin site care once a week seems appropriate.     

A comparison of polyethylene wear rates between cemented and cementless cups. A prospective, randomised trial

We selected randomly a consecutive series of 162 patients requiring hip replacement to receive either a cementless, hemispherical, modular, titanium acetabular cup or a cemented, all-polyethylene cup. These replacements were performed by two surgeons in four general hospitals. The same surgical technique was used and a 26 mm metal-head femoral component was used in every case. After exclusions, 115 hips were studied for differences in rates of wear and osteolysis. The mean clinical follow-up was eight years and the mean radiological follow-up, 6.5 years. The cementless cups wore at a mean rate of 0.15 mm per year and the cemented cups at 0.07 mm per year. This difference was significant (p < 0.0001). Our findings in this mid-term study suggest that cementless cups wear more than cemented cups.     

Acetabular revision surgery with impacted bone allografts and cemented cups in patients younger than 55 years

This article summarises a clinical and radiographical analysis of 30 acetabular revisions in patients younger than 55 years old, performed with impaction bone grafting and cemented cups. Preoperative Merle D’Aubigne and Postel functional score was an average 7 points. At a mean follow-up of 86.5 months (range 34–228) functional score averaged 16.3 points. Radiolucent lines with no clinical impact were observed in 7% of DeLee and Charnley acetabular zones evaluated. Massive radiological migration, consistent with clinical failure, was observed in two cups. Three patients underwent re-revision surgery (10%): two due to infection and one due to mechanical failure. Reconstruction survival rate was 89% (CI 95% 71.9–96.4) overall, and 96% (CI 95% 82.6–99.3) ruling out cases of infection. Impacted bone allograft constitutes one of the reconstructive techniques of choice in acetabular revision surgery of young patients. Restoration of bone stock is essential in this group of patients due to the possibility of future revisions.

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Résumé  Nous avons analysé cliniquement et radiographiquement 30 révisions acétabulaires chez des patients jeunes agés de moins de 55 ans, révision réalisée avec une greffe impactée et une cup cimentée. Le score pré-opératoire de Postel Merle d’Aubigné était en moyenne à 7 points. Après un suivi moyen de 86,5 mois (de 34 à 228 mois) le score post-opératoire de Postel Merle d’Aubigné était en moyenne à 16,3 points. Des liserés sans traduction clinique ont été observés dans 7% des cas et analysés selon DeLee et Charnley. Une migration massive radiographique avec un échec clinique a été observé dans deux cas. 3 patients ont nécessité une nouvelle révision (10%), 2 pour infection et 1 pour échec clinique. Le taux de survie de cette reconstruction a été de 89% (intervalle de confiance 95% 71.9–96.4) et de 96% (intervalle de confiance 95% 82.6–99.3) pour les cas d’infection. L’allogreffe impactée constitue une technique de choix pour la reconstruction lors d’une révision acétabulaire chez des patients jeunes. La restauration du stock osseux est essentielle dans ce groupe de patients et permet d’anticiper de futures révisions.

     

No adverse effects of submelt-annealed highly crosslinked polyethylene in cemented cups: an RSA study of 8 patients 10 yaers after surgery

Background and purpose

Highly crosslinked polyethylene (PE) is in standard use worldwide. Differences in the crosslinking procedure may affect the clinical performance. Experimenatal data from retrieved cups have shown free radicals and excessive wear of annealed highly crosslinked PE. We have previously reported low wear and good clinical performance after 6 years with this implant, and now report on the 10-year results.

Patients and methods

In 8 patients, we measured wear of annealed highly crosslinked PE prospectively with radiostereometry after 10 years. Activity was assessed by UCLA activity score and a specifically designed activity score. Conventional radiographs were evaluated for osteolysis and clinical outcome by the Harris hip score (HHS).

Results

The mean (95% CI) proximal head penetration for highly crosslinked PE after 10 years was 0.07 (–0.015 to 0.153) mm, and the 3D wear was 0.2 (0.026 to 0.36) mm. Without creep, proximal head penetration was 0.02 (–0.026 to 0.066) mm and for 3D penetration was 0.016 (–0.47 to 0.08) mm. This represents an annual proximal wear of less than 2 µm. All cups were clinically and radiographically stable but showed a tendency of increased rotation after 5 years.

Interpretation

Wear for annealed highly crosslinked PE is extremely low up to 10 years. Free radicals do not affect mechanical performance or lead to clinically adverse effects. Creep stops after the first 6 months after implantation. Highly crosslinked PE is a true competitor of hard-on-hard bearings.Highly crosslinked polyethylene (PE) has become a standard option in acetabular cups. Long-term results are still not available, since modern highly crosslinked PE (HXLPE) was introduced into the market around the shift of the millennium (Thomas et al. 2011). Fuelled by the debate about degradation through free radicals (Currier et al. 2007) and preservation of mechanical properties (Tower et al. 2007), there are at least 9 different highly crosslinked PEs with different production protocols commercially available. Although early pilot studies with HXLPE (Oonishi et al. 1998, Grobbelar et al. 1999. Wroblewski et al. 1999) with annealed or remelt-stabilized PE have shown good clinical results, modern first-generation HXLPE was introduced by McKellop (1999) and by Kurtz et al. (1999) in the late 1990s. Since then, second-generation HXLPE with either additives (vitamin E), mechanical enhancement (Kurtz et al. 2006a), or a sequential annealing process have been introduced and promise further improvement. Although HXLPE is in clinical use globally, little is known about the oxidative in vivo stability of these new polyethylenes (Muratoglu et al. 2010).Concerns with annealed (non-remelted) HXLPE are free radicals trapped in the matrix, leading to degradation and excessive wear (Kurtz et al. 2006b, 2011). However, this is not supported by clinical data. So far, it appears that HXLPE reduces the risk of osteolysis (Digas et al. 2007, Jacobs et al. 2007, Callaghan et al. 2008, Kurtz et al. 2011). At the same time, alarming results with increased wear have been reported with remelted HXLPE from retrievals (Muratoglu et al. 2010).We therefore measured femoral head penetration in a cohort with annealed first-generation highly crosslinked polyethylene with radiostereometry. Femoral head penetration is a substitute for in vivo wear measurement (Valstar et al. 2005, Bragdon et al. 2006). We consider it important to report on the 10-year wear measurement for 5 reasons: (1) we used RSA, a high-precision measuring method (Valstar et al. 2005), (2) retrieval studies have shown increased degradation of this HXLPE from oxidation (Currier et al 2007), (3) other HXLPEs have shown increasing wear after 5 years, (4) serum protein may influence wear performance negatively in the long term (St. John 2009), and (5) HXLPE is the most commonly used bearing material in THA worldwide. We therefore update our previous 6-year report on submelt-annealed crosslinked PE (Röhrl et al. 2005, 2007) with 10-year data on wear and clinical outcome.     

No difference between daily and weekly pin site careA randomized study of 50 patients with external fixation

Introduction: We investigated whether there were any differences in the frequency and severity of pin site infections by performing pin site care daily or once a week. We studied patients operated on for gonarthrosis by the hemicallotasis technique, using hydroxyapatite-coated pins in the metaphyseal bone and standard pins in the diaphyseal bone. Patients and methods: 50 patients were prospectively randomized to daily (n= 27) or weekly (n= 23) pin site care. We evaluated pin sites, the occurrence of pain (VAS), the use of antibiotics and analgesics and complications every week. Bacterial cultures were taken from each pin site at 1, 6 and 10 weeks and from the pins on removal. Results: We found no differences between daily or weekly pin site care as regards the frequency and severity of pin site infections, pain, or the use of antibiotics and analgesics. Grade I infections (Checketts-Otterburns classification) occurred around 11% of the pins and grade II infections around 4%. 70% of the bacterial cultures were negative. The most frequent bacteria were coagulase negative staphylococcus and corynebacterium. Antibiotics were given an average of 47 days. More problems occurred around the proximal pins. 5/200 (all proximal) pins were clinically loose on removal. Interpretation: Pin site care once a week seems appropriate.     

No difference between alfacalcidol and paricalcitol in the treatment of secondary hyperparathyroidism in hemodialysis patients: a randomized crossover trial

Alfacalcidol and paricalcitol are vitamin D analogs used for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease, but have known dose-dependent side effects that cause hypercalcemia and hyperphosphatemia. In this investigator-initiated multicenter randomized clinical trial, we originally intended two crossover study periods with a washout interval in 86 chronic hemodialysis patients. These patients received increasing intravenous doses of either alfacalcidol or paricalcitol for 16 weeks, until parathyroid hormone was adequately suppressed or calcium or phosphate levels reached an upper threshold. Unfortunately, due to a period effect, only the initial 16-week intervention period for 80 patients was statistically analyzed. The proportion of patients achieving a 30% decrease in parathyroid hormone levels over the last four weeks of study was statistically indistinguishable between the two groups. Paricalcitol was more efficient at correcting low than high baseline parathyroid hormone levels, whereas alfacalcidol was equally effective at all levels. There were no differences in the incidence of hypercalcemia and hyperphosphatemia. Thus, alfacalcidol and paricalcitol were equally effective in the suppression of secondary hyperparathyroidism in hemodialysis patients while calcium and phosphorus were kept in the desired range.     

Inferior stabilization of cementless compared with cemented dual-mobility cups in elderly osteoarthrosis patients: a randomized controlled radiostereometry study on 60 patients with 2 years’ follow-up

Background and purpose — Elderly patients may benefit from a dislocation low-risk dual-mobility (DM) articulation in total hip arthroplasty, but the best cup fixation method is unknown. We compared cup migration for cemented and cementless DM cups using radiostereometry.Patients and methods — In a patient-blinded randomized trial, 60 patients (33 female) with osteoarthritis were allocated to cemented (n = 30) or cementless (n = 30) Avantage DM cup fixation. Criteria were age above 70 years, and T-score above –4. We investigated cup migration, periprosthetic bone mineral density (BMD), and patient-reported outcome measures (PROMs) until 24 months postoperative follow-up.Results — At 24 months mean proximal cup migration was 0.11 mm (95% CI 0.00–0.23) for cemented cups and 0.09 mm (CI –0.09 to 0.28) for cementless cups. However, cementless cups generally migrated more than cemented cups at 12 and 24 months. Cemented cups had no measurable migration from 3 months’ follow-up, while cementless cups had not yet stabilized at 24 months in all rotations. Cementless cups showed statistically significantly more maximum total point motion (MTPM) at 12- and 24-month follow-up compared with cemented cups in patients with low systemic BMD (p = 0.01). Periprosthetic BMD changes did not statisticially significantly correlate to proximal migration in either cup fixation group (p > 0.05). PROMs improved similarly in both groups.Interpretation — Cemented cups were well fixed at 3 months. The cementless cups migrated more in patients with low BMD, showed an inconsistent pattern of migration, and migrated in different directions during the first and second year without tendency to stabilization. Cemented fixation of the Avantage DM cup seems safer in elderly patients

The most common indication for revision of a conventional primary total hip arthroplasty (THA) is aseptic loosening of the components (SHAR 2016, NJR 2017, DHAR 2018).Implant fixation method (i.e., cemented or cementless) in primary THA seems mainly based on the surgeon’s preference and national trends. The Danish Hip Replacement Registry report shows a decrease in the use of cemented cup fixation in osteoarthrosis (OA) patients above 70 years (DHAR 2018). This trend has also been described in the United Kingdom (UK) and Australian Joint Registries, while in Sweden and Norway cemented cup fixation is still the preferred fixation method in elderly patients (SHAR 2016, NAR 2017, NJR 2017).The dual-mobility (DM) concept, with 2 articulation surfaces and increased jump distance, may decrease the dislocation rate and increase range of motion compared with standard single mobility (SM) THAs. The long-term survival and the best fixation method of the newer Avantage Reload DM cup in elderly patients is currently unknown but retrospective studies on other types of primary DM THAs suggest acceptable survival rates (Batailler et al. 2017) .Excessive early (2-year) implant micromotion measured with radiostereometric analysis (RSA) is a strong predictor for later implant loosening and poor survival (Karrholm et al. 1997, Nieuwenhuijse et al. 2012, Pijls et al. 2012), and our primary aim was to investigate the early RSA-measured migration of cemented and cementless Avantage DM cups in elderly (> 70 years old) OA patients until 24 months’ follow-up. Secondary endpoints included systemic and periprosthetic bone mineral density (BMD) measurements, and clinical outcome scores.     

Similar polyethylene wear between cemented and cementless Oxford medial UKA: a 5-year follow-up randomized controlled trial on 79 patients using radiostereometry

Background and purpose — Hydroxyapatite (HA)-coated implants have been associated with high polyethylene wear in hip arthroplasties. HA coating as a promoter of wear in knee arthroplasties has not been investigated. We compared the wear-rate of the polyethylene bearing for cemented and cementless HA-coated Oxford medial unicondylar knee arthroplasties (UKA). Secondarily, we investigated whether wear-rates were influenced by overhang or impingement of the bearing.

Patients and methods — 80 patients (mean age 64 years), treatment-blinded, were randomized to 1 of 3 Oxford medial UKA versions: cemented with double-pegged or single-pegged femoral component or cementless HA-coated with double-pegged femoral component (ratios 1:1:1). We compared wear between the cemented (n = 55) and cementless group (n = 25) (ratio 2:1). Wear, impingement, and overhang were quantified between surgery and 5-year follow-up using radiostereometry. Clinical outcome was evaluated with the Oxford Knee Score.

Results — The mean wear-rate for patients without bearing overhang was 0.04?mm/year (95% CI 0.02–0.07) for the cemented group and 0.05?mm/year (CI 0.02–0.08) for the cementless group. The mean difference in wear was 0.008?mm/year (CI –0.04 to 0.03). No impingement was identified. Half of the patients had medial bearing overhang, mean 2.5?mm (1–5). Wear increased by 0.014?mm/year for each mm increment in overhang. The mean Oxford Knee Score was 39 for the cementless group and 38 for the cemented group at the 5-year follow-up.

Interpretation — The wear-rates were similar for the 2 fixation methods, which supports further use of the cementless Oxford medial UKA. However, a caveat is a relatively large 95% CI of the mean difference in wear-rate. Component size and position is important as half of the patients presented with an additional increase in wear-rate due to medial bearing overhang.

Trial registration: ClinicalTrials.gov identifier: NCT00679120.     

Preliminary results in 167 bioceramic cemented arthroplasties with five-year follow-up in patients aged 60 years or over

A total of 167 ceramic-ceramic cemented arthroplasties with a mean follow-up of 62.5 months were evaluated. There were no signs of loosening in the femoral components. Loosening of the acetabulum was observed in 5 patients. A statistical study conducted on the two groups (the first aged under 70 years, the second aged 70 or over) did not reveal any relationship between failure of the acetabular component and the age of the patient. An evaluation of bone density based on the DXA system in 5 cases of loosening revealed its diminution in relation to follow-up parameters. Based on our experience, implantation of the ceramic-ceramic cemented prosthesis is a reliable choice in patients with good bone trophism, in those where there is a significant reduction in bone density; it is best to use polyethylene-ceramic implants.     

Very low wear of non-remelted highly cross-linked polyethylene cups: An RSA study lasting up to 6 years

Background and purpose?Highly cross-linked polyethylenes (PEs) all appear to reduce wear dramatically in laboratory studies, although there is substantial variation in this respect between manufacturers. Nonremelted cross-linked PE is almost as tough as unirradiated PE, but is not completely stable and can oxidize in vivo, as has been shown in recent retrievals studies.

We had reported low wear and good clinical performance after 2 years for 10 non-remelted highly crosslinked PE cups compared to 16 conventional PE cups sterilized by gamma-in-air.

Method?Because of possible degradation by free radicals, we followed up both cohorts for 5 years (conventional PE) and 6 years (highly cross-linked PE).

Result?Mean (CI) proximal head penetration over the observation time was linear and measured 0.08 (0.02–0.13) mm for cross-linked PE and 0.42 (0.23–0.62) mm for conventional PE, and total penetration was 0.23 (0.1–0.35) mm and 0.75 (0.05–1.4) mm respectively. After subtracting creep, the annual wear for non-remelted highly cross-linked PE was below 6 µm. The cups had equally low migration and few radiolucencies.

Interpretation?The theoretical possibility of oxidation in non-remelted highly cross-linked PE may not show clinically. However, it may be that cemented cups with their thicker PE are more forgiving than metal-backed cups with thin PE moving in the locking mechanism. So far, we can conclude that the Crossfire highly crosslinked polyethylene cups performed very well clinically, with extremely low wear even after almost 6 years. This is reassuring, but care should be taken in extrapolating these results to other cross-linked PEs or uncemented cups where toughness of PE is more of an issue.     

Very low wear of non-remelted highly cross-linked polyethylene cups: an RSA study lasting up to 6 years

Background and purpose Highly cross-linked polyethylenes (PEs) all appear to reduce wear dramatically in laboratory studies, although there is substantial variation in this respect between manufacturers. Nonremelted cross-linked PE is almost as tough as unirradiated PE, but is not completely stable and can oxidize in vivo, as has been shown in recent retrievals studies.

We had reported low wear and good clinical performance after 2 years for 10 non-remelted highly crosslinked PE cups compared to 16 conventional PE cups sterilized by gamma-in-air.

Method Because of possible degradation by free radicals, we followed up both cohorts for 5 years (conventional PE) and 6 years (highly cross-linked PE).

Result Mean (CI) proximal head penetration over the observation time was linear and measured 0.08 (0.02-0.13) mm for cross-linked PE and 0.42 (0.23-0.62) mm for conventional PE, and total penetration was 0.23 (0.1-0.35) mm and 0.75 (0.05-1.4) mm respectively. After subtracting creep, the annual wear for non-remelted highly cross-linked PE was below 6 µm. The cups had equally low migration and few radiolucencies.

Interpretation The theoretical possibility of oxidation in non-remelted highly cross-linked PE may not show clinically. However, it may be that cemented cups with their thicker PE are more forgiving than metal-backed cups with thin PE moving in the locking mechanism. So far, we can conclude that the Crossfire highly crosslinked polyethylene cups performed very well clinically, with extremely low wear even after almost 6 years. This is reassuring, but care should be taken in extrapolating these results to other cross-linked PEs or uncemented cups where toughness of PE is more of an issue.     

Reduced wear in vitamin E-infused highly cross-linked polyethylene cups: 5-year results of a randomized controlled trial

Background and purpose — Vitamin E-infused polyethylene is a relatively new material in joint arthroplasty; there are no long-term reports, and only few mid-term results. Using radiostereometric analysis (RSA), we primarily determined whether vitamin E-infused highly cross-linked polyethylene (HXLPE/VitE) acetabular cups show less wear than ultra-high molecular weight polyethylene (UHMWPE) acetabular cups at 5 years after total hip arthroplasty (THA). We also assessed whether wear rates correlate with increasing cup inclination angles or cup sizes.Patients and methods — This is a 5-year follow-up of our previously reported randomized controlled trial of 62 patients with 3 years’ follow-up, who received THA with either an HXLPE/VitE or a UHMWPE acetabular cup. At 5 years, 40 patients were analyzed (22 in the HXLPE/VitE and 18 in the UHMWPE group).Results — HXLPE/VitE cups continued to show less cumulative femoral head penetration than UHMWPE cups (HXLPE/VitE: 0.24 mm, UHMWPE: 0.45 mm; p < 0.001). Distribution of wear was also more even with HXLPE/VitE cups than with UHMWPE cups (p = 0.002). Moreover, the difference in PE wear between 1 and 5 years in both groups showed no statistically significant correlation with increasing cup inclination angles or cup sizes. Finally, no osteolysis and implant loosening occurred, and no revision surgeries were required.Interpretation — Wear rates continue to be lower in HXLPE/VitE cups than in UHMWPE cups at 5 years of follow-up without correlation with increasing cup inclination angles or cup sizes. Finally, HXLPE/VitE cups may have the potential to prevent osteolysis and implant loosening.

Wear of the polyethylene (PE) component of total hip arthroplasties (THA) may result in osteolysis (Callary et al. 2015). Therefore, attempts such as cross-linking using irradiation and addition of vitamin E have been made to improve the wear properties of PE (Galea et al. 2019). Vitamin-E infused highly cross-linked polyethylene (HXLPE/VitE) has been developed to reduce the number of free radicals without compromising the mechanical properties. There are 2 methods of incorporating vitamin E into PE. The 1st is to blend vitamin E with PE powder before consolidation and. Once consolidated, the blend can be irradiated for sterilization or cross-linking. The 2nd is diffusion of vitamin E into the PE after radiation cross-linking: after PE is irradiated for cross-linking, it is diffused with vitamin E, then machined into its final form and gamma sterilized (Oral et al. 2005). Gamma irradiation causes crosslinking of UHMWPE, which changes its property from the original. However, it causes reduction in tensile strength and elongation of UHMWPE, and leads to long-lived free radicals that react with oxygen (Oral et al. 2007).As HXLPE/VitE is a relatively new material in orthopedic surgery, studies on its wear properties with longer follow-up periods are still limited (Nebergall et al. 2016, 2017, Shareghi et al. 2017, Galea et al. 2019). Our initial 3-year data showed less wear with HXLPE/VitE, which may prevent osteolysis, implant loosening, and eventually revision surgery (Rochcongar et al. 2018). We have now investigated clinical and radiographic outcomes of our previously reported patient cohort at 5-year follow-up. The primary objective is to know whether HXLPE/VitE acetabular cups continue to show less PE wear than ultra-high molecular weight polyethylene (UHMWPE) acetabular cups at 5 years. The secondary objective is to evaluate the correlation between PE wear rates with cup inclination angles or cup sizes, in addition to reporting clinical outcomes.      

Cemented tibial component fixation performs better than cementless fixation: a randomized radiostereometric study comparing porous-coated, hydroxyapatite-coated and cemented tibial components over 5 years

Background The question whether the tibial component of a total knee arthroplasty should be fixed to bone with or without bone cement has not yet been definitely answered. We studied movements between the tibial component and bone by radiostereometry (RSA) in total knee replacement (TKR) for 3 different types of fixation: cemented fixation (C-F), uncemented porous fixation (UC-F) and uncemented porous hydroxyapatite fixation (UCHA-F).

Patients 116 patients with osteoarthrosis, who had 146 TKRs, were included in 2 randomized series. The first series included 86 unilateral TKRs stratified into 1 of the 3 types of fixation. The second series included 30 patients who had simultaneous bilateral TKR surgery, and who were stratified into 3 subgroups of pairwise comparisons of the 3 types of fixation.

Results After 5 years 2 knees had been revised, neither of which were due to loosening. 1 UCHA-F knee in the unilateral series showed a large and continuous migration and a poor clinical result, and is a pending failure. The C-F knees rotated and migrated less than UC-F and UCHA-F knees over 5 years. UCHA-F migrated less than UC-F after 1 year.

Interpretation Cementing of the tibial component offers more stable bone-implant contact for 5 years compared to uncemented fixation. When using uncemented components, however, there is evidence that augmenting a porous surface with hydroxyapatite may mean less motion between implant and bone after the initial postoperative year.     

Equally good fixation of cemented and uncemented cups in total trapeziometacarpal joint prostheses: A randomized clinical RSA study with 2-year follow-up

To determine the value of reduction of fractures of the distal radius in the very elderly and low-demand or demented patient, we assessed 60 fractures in 59 patients for the reduction achieved and maintained. The mean patient age was 82 (65-93) years. All fractures were initially reduced under regional or general anaesthesia. In 44 dorsally displaced fractures, reduction failed in 7 cases initially, and 37 lost reduction during the following weeks of immobilisation in plaster. In 9 wrists with volarly displaced fractures, reduction was achieved in 6; all malunited. A total of 53/60 fractures healed in a malunited position. We found no correlation between fracture classification, initial displacement, and final radiographical outcome. On the basis of these observations we conclude that reduction of fractures of the distal radius is of minimal value in the very old and frail, dependent or demented patient.