Minimum 10-Year Follow-Up of Cementless Total Hip Arthroplasty With a 32-mm Cobalt-Chromium Head on Highly Cross-Linked Polyethylene and a Tapered, Fiber Metal Proximally Coated Femoral Stem

Minimum 7-year results of cementless total hip arthroplasty with vitamin E-diffused and 2-methacryloyloxyethyl phosphorylcholine-grafted highly cross-linked polyethylene

The purpose of this study was to evaluate the mid-term clinical results and polyethylene wear of vitamin E-diffused highly cross-linked polyethylene (HXLPE) and 2-methacryloyloxyethyl phosphorylcholine (MPC)-grafted HXLPE in cementless total hip arthroplasty (THA). Thirty-four THAs with vitamin E-diffused HXLPE (VEPE) and 32-mm cobalt-chromium head, and 116 THAs with MPC-grafted HXLPE and 32-mm alumina head were evaluated. The Merle d'Aubigné and Postel scores were administered. Kaplan-Meier survivorship was analyzed. Annual radiographs were analyzed using computerized method and linear steady-state wear rate was measured. The mean duration of follow-up was 9 years (range, 7-11 years) in VEPE group and 8 years (range, 7-10 years) in MPC group. The mean Merle d'Aubigné and Postel scores improved postoperatively in both groups. Kaplan-Meier survivorship with endpoint of revision was 100% (95% confidence interval, 100%-100%) in VEPE group and 98.3% (95% confidence interval, 93.4%-99.6%) in MPC group at 10 years (P = .44). The mean steady-state wear rate was 0.007 mm/year in VEPE group and 0.006 mm/year in MPC group (P = .60). The clinical results of both groups were good and wear rates of both liners were very low.

Total hip arthroplasty using an alkali- and heat-treated titanium Zweymüller stem with no trochanteric shoulder: results at 5-year follow-up

BACKGROUND

A trochanteric shoulder is 1 of the characteristics of the original Zweymüller femoral stem for total hip arthroplasty (THA). There have been few clinical reports of THA using recently available versions of Zweymüller-type stems with eliminated trochanteric shoulder.

METHODS

82 consecutive THAs with a Zweymüller-type stem without trochanteric shoulder were analyzed. The stem was made of alkali- and heat-treated titanium, straight, tapered, with rectangular cross-section. Survivorship was estimated with the Kaplan-Meier method.

RESULTS

76 of 82 hips (92.7%) were followed for more than 5 years or until revision. 35 of 82 hips (42.7%), were revised and the predominant reason for revision was aseptic loosening of the femoral stem (34 of 35 hips, 97.1%). Survival with revision for any reason as the endpoint was 71.3% (95% CI, 51.8% to 80.1%) at 5 years.

CONCLUSIONS

The survival of the modified Zweymüller-type stem with no trochanteric shoulder was unacceptably low.

Ultra-High-Molecular-Weight Polyethylene in Hip and Knee Arthroplasties

Ultra-high-molecular-weight polyethylene (UHMWPE) wear and particle-induced osteolysis contribute to the failure of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Highly crosslinked polyethylene (HXLPE) was developed in the late 1990s to reduce wear and has shown lower wear rates and loosening than conventional UHMWPE in THA. The irradiation dose for crosslinking is up to 100 kGy. However, during crosslinking, free radical formation induces oxidation. Using HXLPE in THA, the cumulative revision rate was determined to be significantly lower (6.2%) than that with conventional UHMWPE (11.7%) at a mean follow-up of 16 years, according to the Australian Orthopaedic Association National Joint Replacement Registry. However, HXLPE does not confer to TKA the same advantages it confers to THA. Several alternatives have been developed to prevent the release of free radicals and improve polymer mechanical properties, such as thermal treatment, phospholipid polymer 2-methacryloyloxyethyl phosphorylcholine grafting, remelting, and vitamin E addition. Among these options, vitamin E addition has reported good clinical results and wear resistance similar to that of HXLPE without vitamin E, as shown by short-term clinical studies of THA and TKA. This review aims to provide a comprehensive overview of the development and performance of UHMWPE in THA and TKA.

Long-term outcome of primary total hip arthroplasty with cementless bioactive glass ceramic bottom-coated implants and highly cross-linked polyethylene: A minimum 10-year analysis

BACKGROUND

Cementless glass ceramics containing apatite and wollastonite (AW-GC) bottom-coated titanium hip implants were developed; early excellent clinical and radiographic results have been reported previously. This study aimed to investigate the long-term clinical and radiographic outcomes in detail, and the wear rate of HXLPE.

METHODS

We retrospectively evaluated 99 patients (117 hips) between November 2001 and December 2007. The survival rate was estimated using the Kaplan-Meier method. Hip joint function was evaluated using the Japanese Orthopaedic Association (JOA) score. The extent of radiographic signs was determined from the radiographs performed at the last follow-up. Polyethylene wear was measured using Martell's Hip Analysis Suite. We assessed the possible factors affecting the steady-state linear wear rate.

RESULTS

The mean follow-up period was 14.8 ± 2.1 (10-18.6) years. The mean JOA score improved to 88.7 ± 9.4 (59-100) at the final follow-up from 47.8 ± 12.5 (17-76) before surgery. The overall survival rate with the end point of all-cause revision and wear-related revision was 99% and 100% respectively. There was no osteolysis or loosening of either the acetabular or femoral component. All hips were classified as having bone ingrowth fixation. The mean steady-state wear rate was 0.008 ± 0.025 mm/year. We found no significant correlation between the wear rate and age, body weight, body mass index, cup inclination and femoral head size.

CONCLUSION

The combination of AW-GC bottom-coated implants and HXLPE showed excellent implant survival and wear resistance for 15 years.

Open-porous magnesium-based scaffolds withstand in vitro corrosion under cyclic loading: A mechanistic study

The successful application of magnesium (Mg) alloys as biodegradable bone substitutes for critical-sized defects may be comprised by their high degradation rate resulting in a loss of mechanical integrity. This study investigates the degradation pattern of an open-porous fluoride-coated Mg-based scaffold immersed in circulating Hanks' Balanced Salt Solution (HBSS) with and without in situ cyclic compression (30 N/1 Hz). The changes in morphological and mechanical properties have been studied by combining in situ high-resolution X-ray computed tomography mechanics and digital volume correlation. Although in situ cyclic compression induced acceleration of the corrosion rate, probably due to local disruption of the coating layer where fatigue microcracks were formed, no critical failures in the overall scaffold were observed, indicating that the mechanical integrity of the Mg scaffolds was preserved. Structural changes, due to the accumulation of corrosion debris between the scaffold fibres, resulted in a significant increase (p < 0.05) in the material volume fraction from 0.52 ± 0.07 to 0.47 ± 0.03 after 14 days of corrosion. However, despite an increase in fibre material loss, the accumulated corrosion products appear to have led to an increase in Young's modulus after 14 days as well as lower third principal strain (εp3) accumulation (−91000 ± 6361 με and −60093 ± 2414 με after 2 and 14 days, respectively). Therefore, this innovative Mg scaffold design and composition provide a bone replacement, capable of sustaining mechanical loads in situ during the postoperative phase allowing new bone formation to be initially supported as the scaffold resorbs.

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First report on in vitro cyclic loading of MgF₂ coated open-porous Mg scaffolds in HBSS simulating 2–3 months in humans.

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Fluoride-coating slows down corrosion under cyclic loading in vitro.

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Entangled scaffold structure accumulates local corrosion debris which keeps the mechanical integrity over 14 days in vitro.

Effects of porous tantalum on periprosthetic bone remodeling around metaphyseal filling femoral stem: a multicenter, prospective, randomized controlled study

Periprosthetic bone loss due to adaptive bone remodeling is an important unresolved issue in cementless total hip arthroplasty (THA). The use of porous tantalum on the proximal surface of the femoral stem is expected to decrease postoperative bone loss around the prosthesis through early fixation. We conducted a multicenter randomized controlled study to determine if porous tantalum could reduce periprosthetic bone loss after THA. From October 2012 to September 2014, 118 patients (mean age, 61.5 years; 107 females and 11 males) were prospectively enrolled and were randomly allocated at a ratio of 1:1 to either a metaphyseal filling stem with a proximal porous tantalum coating (Trabecular Metal) or a conventional metaphyseal filling stem with fiber mesh coating (VerSys). Patients underwent dual-energy x-ray absorptiometry scans within 1 week after surgery (baseline) and at 6, 12, and 24 months after surgery to assess periprosthetic bone mineral density (BMD) in the 7 Gruen zones. In addition, the Japanese Orthopaedic Association hip score was assessed before surgery and at 6, 12, and 24 months after surgery. In the proximal periprosthetic region (zones 1 and 7), the Trabecular Metal group had significantly smaller reductions in BMD than the VerSys group throughout the study period. In the VerSys group, significant reductions in BMD compared to baseline were seen at each measurement point in all regions, except in zone 6 at 24 months. In the Trabecular Metal group, no significant reductions in BMD relative to baseline were seen in zones 1, 5, or 6 throughout the study period. Both groups demonstrated similar improvement in Japanese Orthopaedic Association hip scores over the study period. This study demonstrated that a proximally coated stem with porous tantalum has superior results over a conventional stem with titanium fiber mesh in terms of periprosthetic bone remodeling.