2-year results of an RCT of 2 uncemented isoelastic monoblock acetabular components: lower wear rate with vitamin E blended highly cross-linked polyethylene compared to ultra-high molecular weight polyethylene.

Background and purpose - The long-term survival of arthroplasty components may be limited by polyethylene wear-related problems such as periprosthetic osteolysis and aseptic loosening. Highly cross-linked polyethylene (HXLPE) blended with vitamin E was introduced to improve oxidative stability and to avoid long-term embrittlement. This study clinically compares the tribological behavior and clinical outcome of vitamin E blended HXLPE with ultra-high molecular weight polyethylene (UHMWPE) in an isoelastic monoblock cup for uncemented total hip arthroplasty.Patients and methods - In this randomized controlled trial (RCT), 199 patients were included: 102 patients received the vitamin E blended HXLPE cup, 97 patients the UHMWPE cup. Clinical and radiographic parameters were obtained preoperatively, directly postoperative and at 3, 12, and 24 months. Wear rates were compared using the mean linear femoral head penetration (FHP) rate.Results - 188 patients (94%) completed the 2-year follow-up. Mean patient satisfaction was higher in the vitamin E blended HXLPE group (8.9 [1]) than in in the control group (8.5 [2], p = 0.03). The Harris Hip Score (HHS) was higher in the vitamin E blended HXLPE group (95 [8]) than in the control group (92 [11], p = 0.3). The FHP rate was lower in the vitamin E blended HXLPE group: 0.046 mm/year compared with 0.056 mm/year in the control group (p = 0.05). No adverse reactions associated with the clinical application of vitamin E blended HXLPE were observed during follow-up, with an excellent 2-year survival to revision rate of 98% for both cups.Interpretation - This study shows the superior performance of the HXLPE blended with vitamin E acetabular cup with lower linear femoral head penetration rates and better clinical results compared with the UHMWPE acetabular cup after 2 years.

Longterm outcome of 886 posterior malleolar fractures: A systematic review of the literature.

INTRODUCTION: The objective of the present study was to review the current data on the long-term outcomes of posterior malleolar fractures, with special emphasis on the role of the type of treatment, surgical approach, and reduction and internal fixation. METHODS: The search was limited to skeletally mature patients. Major databases were searched from 1978 to 2014 to identify studies relating to functional outcome, subjective outcome, and radiographic evaluation at least 2 years after either surgical or conservative treatment of posterior malleolar fractures. RESULTS: Of 68 initially relevant studies, 19 met our inclusion criteria. A total of 886 fractures were identified in 885 patients. The mean sample size-weighted follow-up period was 3.7 years. Comparable results are achieved when comparing open reduction and internal fixation to conservative treatment for posterior malleolar fractures. DISCUSSION: Current consensus suggests posterior malleolar fragments comprising of >25% of the distal tibial plafond as seen on a true lateral radiograph and fragments with more than 2mm dislocation require open reduction and internal fixation of the fragment. The current consensus on treatment of posterior malleolar fractures is neither supported nor disapproved by the available evidence.

An uncemented iso-elastic monoblock acetabular component: preliminary results.

Little is known about the clinical application of highly cross-linked polyethylene (HXLPE) blended with vitamin E. This study evaluates an uncemented iso-elastic monoblock cup with vitamin E blended HXLPE. 112 patients were followed up for 2years. 95.5% completed the follow-up. The mean VAS score for patient satisfaction was 8.8 and the mean Harris Hip Score was 94.2. In 7 cases initial gaps behind the cup were observed, which disappeared completely during follow-up in 6 cases. The mean femoral head penetration rate was 0.055mm/year. No adverse reactions or abnormal mechanical behavior was observed with the short term use of vitamin E blended HXLPE. This study shows the promising performance of this cup and confirms the potential of vitamin E blended HXLPE.

Poor intermediate-term survival of the uncemented Optan anatomically adapted femoral component.

PURPOSE: We evaluated the 5-year survival of the uncemented Optan anatomically adapted femoral stem, with revision for aseptic loosening as the endpoint. METHODS: Between January 2004 and March 2007, 432 total hip arthroplasties (THAs) were performed in 432 patients. After follow-up for a mean time of 5 years, the patients were evaluated using the WOMAC questionnaire and plain radiography. Patients who were unable to attend the follow-up visit were contacted by telephone to determine whether they had had any revision surgery of their THA. RESULTS: Within 5 years, 39 patients (9%) had died of unrelated causes and 63 patients (15%) had been lost to follow-up. Of the remaining cohort, 224 patients (68%) had full follow-up while 88 patients (27%) were evaluated with WOMAC only and 18 patients (5%) were evaluated with radiography only. The mean WOMAC score of all evaluated patients was 21 (10-100). At 5-year follow-up, there were 26 stem revisions reported (6%), 14 hips (3%) showed aseptic loosening, and 12 hips (3%) had had a periprosthetic femoral fracture. The 5-year survival to revision for any reason was 94%. Worst-case analysis yielded a 5-year survival of 79%. INTERPRETATION: The 5-year survival for aseptic loosening of the Optan anatomically adapted femoral component was disappointing. Radiographic evaluation showed evidence of proximal radiolucencies and distal cortical bone hypertrophy, which we attribute to insufficient proximal bone in-growth and increased load transfer at the tip of the stem. We do not recommend the use of the Optan femoral stem.

Edge loading does not increase wear rates of ceramic-on-ceramic and metal-on-polyethylene articulations.

The mal-positioning of total hip arthroplasty components can result in edge loading conditions. Purpose of this study was to determine if the wear rate of ceramic-on-ceramic and metal-on-polyethylene increases under edge loading conditions. The literature was reviewed to determine which of the commonly used hip bearings is the most forgiving to implant mal-orientation. Two 28-mm ceramic-on-ceramic articulations were tested in vitro: pure alumina (PAL) ceramic versus the new alumina-toughened zirconia (ATZ). Two 28-mm metal-on-polyethylene articulations were tested in vitro: conventional ultrahigh molecular weight polyethylene (UHMWPE) versus highly crosslinked polyethylene (HXLPE) stabilized with vitamin E. All bearings were tested at standard and at highest possible inclination angles. Hip simulator tests were run for five million cycles based on N = 3 tests per condition. The average wear rate of ATZ-on-ATZ is 0.024 mm(3) /Mcycles at 45° and 0.018 mm(3) /Mcycles at 65°. Wear rate of PAL-on-PAL is between 0.02 and 0.03 mm(3) /Mcycles at 45°, as well as 65°. The wear rate of UHMWPE was 31 ± 1 mm(3) /Mcycles at an inclination angle of 45° and 26 ± 1 mm(3) /Mcycles at 80°. The wear rate of vitamin E stabilized HXLPE was 5.9 ± 0.2 mm(3) /Mcycles at 45° and 5.8 ± 0.2 mm(3) /Mcycles at 80°. Edge loading does not increase the wear rate of ceramic-on-ceramic and metal-on-polyethylene articulations. The newest biomaterials showed markedly lower wear rates compared with their conventional counterparts. ATZ-on-ATZ showed the lowest wear rate of all tested pairings, but the vitamin E stabilized HXLPE seems to be the most forgiving material when it comes to implant mal-orientation.

Excellent survivorship of the Morscher monoblock cup with a 28-mm Metasul-on-Metasul bearing at a mean of 5-year follow-up.

The Morscher monoblock cup is designed for optimal osteointegration and holds the potential for excellent long-term survival. The Metasul-on-Metasul bearing was introduced to eliminate wear-induced periprosthetic osteolysis. This study reviews 137 Morscher cups with a 28-mm Metasul-on-Metasul bearing used in primary THA at 5.1years (3.2-6.6) after implantation. One hundred thirty-seven cups were implanted in 119 patients. Three patients (2.2%) had died of unrelated causes, and 10 patients (8.0%) were lost to follow-up. The mean Harris Hip score was 89.8 and the mean WOMAC sum score was 18.5. No cases of acetabular osteolysis were found. The 5-year cup survival rate was 98.5%. The Morscher cup with a 28-mm Metasul-on-Metasul bearing used in uncemented THA showed no acetabular osteolysis and promising survivorship at intermediate-term follow-up.

Do monoblock cups improve survivorship, decrease wear, or reduce osteolysis in uncemented total hip arthroplasty?

BACKGROUND: Monoblock acetabular components used in uncemented total hip arthroplasty (THA) have certain mechanical characteristics that potentially reduce acetabular osteolysis and polyethylene wear. However, the degree to which they achieve this goal is not well documented. QUESTIONS/PURPOSES: The purpose of this study was to use a systematic review of controlled trials to test the hypothesis that monoblock cups have superior (1) polyethylene wear rate; (2) frequency of cup migration; (3) frequency of acetabular osteolysis; and (4) frequency of aseptic loosening compared with modular components used in uncemented THA. METHODS: A systematic search was conducted in the Medline, Embase, and Cochrane electronic databases to assemble all controlled trials comparing monoblock with modular uncemented acetabular components in primary THA. Included studies were considered "best evidence" if the quality score was either ≥ 50% on the Cochrane Back Review Group checklist or ≥ 75% the Newcastle-Ottawa quality assessment scale. A total of seven publications met our inclusion criteria. RESULTS: Best evidence analysis showed no difference in polyethylene wear rate, the frequency of cup migration, and aseptic loosening between monoblock and modular acetabular components. No convincing evidence was found for the claim that lower frequencies of acetabular osteolysis are observed with the use of monoblock cups compared with modular uncemented cups. CONCLUSIONS: The purported benefits of monoblock cups were not substantiated by this systematic review of controlled studies in that polyethylene wear rates and frequencies of cup failure and acetabular osteolysis were similar to those observed with modular implants. Other factors should therefore drive implant selection in cementless THA.