All-polyethylene Component Research Articles

All-Polyethylene Tibial Components: An Analysis of Long-Term Outcomes and Infection

BackgroundThere is debate regarding tibial component modularity and composition in total knee arthroplasty (TKA). Biomechanical studies have suggested improved stress distribution in metal-backed tibias; however, these results have not translated clinically. The purpose of this study was to analyze the outcomes of all-polyethylene components and to compare the results to those with metal-backed components. MethodsWe reviewed 31,939 patients undergoing a primary TKA over a 43-year period (1970-2013). There were 28,224 (88%) metal-backed and 3715 (12%) all-polyethylene tibial components. The metal-backed and all-polyethylene groups had comparable demographics with respect to gender, age and body mass index (BMI). Mean follow-up was 7 years. ResultsThe mean survival for all primary TKAs at the 5-, 10-, 20- and 30-year time points was 95%, 89%, 73%, and 57%, respectively. All-polyethylene tibial components were found to have a significantly improved (P < .0001) survivorship when compared with their metal-backed counterparts. All-polyethylene tibial components were also found to have a significantly lower rate of infection, instability, tibial component loosening, and periprosthetic fracture. The all-polyethylene group had improved survival rates in all age groups, except in patients 85 years old or greater, where there was no significant difference. All-polyethylene tibial components had improved survival for all BMI groups except in the morbidly obese (BMI ≥ 40) where there was no significant difference. ConclusionAll-polyethylene tibial components had significantly improved implant survival, reduced rates of postoperative infection, fracture, and tibial component loosening. All polyethylene should be considered for most of the patients, regardless of age and BMI.

A Finite-Element Study of Metal Backing and Tibial Resection Depth in a Composite Tibia Following Total Knee Arthroplasty.

Prosthetic alignment, patient characteristics, and implant design are all factors in long-term survival of total knee arthroplasty (TKA), yet the level at which each of these factors contribute to implant loosening has not been fully described. Prior clinical and biomechanical studies have indicated tibial overload as a cause of early TKA revision. The purpose of this study was to determine the relationship between tibial component design and bone resection on tibial loading. Finite-element analysis (FEA) was performed after simulated implantation of metal backed (MB) and all-polyethylene (AP) TKA components in 5 and 15 mm of tibial resection into a validated intact tibia model. Proximal tibial strains significantly increased between 13% and 199% when implanted with AP components (p < 0.05). Strain significantly increased between 12% and 209% in the posterior tibial compartment with increased bone resection (p < 0.05). This study indicates elevated strains in AP implanted tibias across the entirety of the proximal tibial cortex, as well as a posterior shift in tibial loading in instances of increased resection depth. These results are consistent with trends observed in prior biomechanical studies and may associate the documented device history of tibial collapse in AP components with increased bone strain and overload beneath the prosthesis.

A randomised trial of all-polyethylene and metal-backed tibial components in unicompartmental arthroplasty of the knee.

This randomised trial evaluated the outcome of a single design of unicompartmental arthroplasty of the knee (UKA) with either a cemented all-polyethylene or a metal-backed modular tibial component. A total of 63 knees in 45 patients (17 male, 28 female) were included, 27 in the all-polyethylene group and 36 in the metal-backed group. The mean age was 57.9 years (39.6 to 76.9). At a mean follow-up of 6.4 years (5 to 9.9), 11 all-polyethylene components (41%) were revised (at a mean of 5.8 years; 1.4 to 8.0) post-operatively and two metal-backed components were revised (at one and five years). One revision in both groups was for unexplained pain, one in the metal-backed group was for progression of osteoarthritis. The others in the all-polyethylene group were for aseptic loosening. The survivorship at seven years calculated by the Kaplan-Meier method for the all-polyethylene group was 56.5% (95% CI 31.9 to 75.2, number at risk 7) and for the metal-backed group was 93.8% (95% CI 77.3 to 98.4, number at risk 16) This difference was statistically significant (p < 0.001). At the most recent follow-up, significantly better mean Western Ontario and McMaster Universities Arthritis Index Scores were found in the all-polyethylene group (13.4 vs 23.0, p = 0.03) but there was no difference in the mean Knee injury and Osteoarthritis Outcome scores (68.8; 41.4 to 99.0 vs 62.6; 24.0 to 100.0), p = 0.36). There were no significant differences for range of movement (p = 0.36) or satisfaction (p = 0.23). This randomised study demonstrates that all-polyethylene components in this design of fixed bearing UKA had unsatisfactory results with significantly higher rates of failure before ten years compared with the metal-back components.

All-Polyethylene Tibial Components for Unicompartmental Knee Arthroplasty

All-polyethylene and metal-backed tibial components are available for unicompartmental knee arthroplasty. Although the early design of all-polyethylene component was largely replaced by metal-backed components, improvements in polyethylene wear characteristics, component design, and surgical technique have renewed interest in all-polyethylene (InLay) components. In comparison with metal-backed (OnLay) designs, InLays require less bone resection and are easier to revise total knee replacements. Early aseptic loosening, tibial component subsidence, and anterior knee pain were found to be the primary contributors to failure of InLay designs. Controversy remains whether InLay or OnLay components are preferable for unicompartmental knee arthroplasty. Despite the component design, proper component alignment, cementation technique, and ligamentous balance remain crucial for implant survival and are highlighted in this article along with a comparison of InLay and OnLay results.

Metal-Backed Glenoid Components Have a Higher Rate of Failure and Fail by Different Modes in Comparison with All-Polyethylene Components: A Systematic Review.

Glenoid component failure is a common and serious complication of total shoulder arthroplasty. The purpose of this study was to evaluate published evidence on whether metal backing lessens the rate of glenoid component failure. A comprehensive systematic review yielded twenty-one studies on radiolucency, radiographic failure, and revision after arthroplasty with metal-backed glenoid components and twenty-three studies with all-polyethylene components. Our analysis included data on 1571 metal-backed and 3035 all-polyethylene components. The mean duration of follow-up was 5.8 years in the studies with metal-backed components and 7.3 years with all-polyethylene components. All-polyethylene components had a 42.5% rate of radiolucency compared with 34.9% for metal-backed components (p = 0.0026) and a 21.1% rate of radiographic loosening or failure compared with 16.8% for metal-backed components (p = 0.0005). However, the rate of revision was more than three times higher with metal-backed components (14.0%) than with all-polyethylene components (3.8%, p < 0.0001). Although 77% of the revisions of all-polyethylene components were for loosening, 62% of the revisions of metal-backed components were for other reasons, such as component fracture, screw breakage, component dissociation, polyethylene wear, metal wear, and rotator cuff tear (p < 0.0001). The published evidence indicates that metal-backed glenoid components require revision at a significantly higher rate and for different reasons in comparison with all-polyethylene components. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

All-Polyethylene Versus Metal-Backed Tibial Components-An Analysis of 27,733 Cruciate-Retaining Total Knee Replacements from the Swedish Knee Arthroplasty Register.

Currently, the use of metal-backed tibial components is more common than the use of all-polyethylene components in total knee arthroplasty. However, the available literature indicates that all-polyethylene tibial components are not inferior to the metal-backed design. We hypothesized that there would be no difference in the ten-year survival rate between all-polyethylene and metal-backed tibial components of a specific design in a large nationwide cohort. In the Swedish Knee Arthroplasty Register, we identified 27,733 cruciate-retaining total knee replacements using the press-fit condylar prosthesis with either metal-backed or all-polyethylene tibial components inserted from 1999 to 2011. Unadjusted survival functions were calculated with the end points of revision for any reason, revision due to infection, and revision due to reasons other than infection, and the differences between the groups were investigated with the log-rank test. Cox proportional hazard models were fitted to analyze the influence of various covariates on the adjusted relative risk of revision. The median duration of follow-up was 4.5 years (range, zero to 12.9 years). Of all total knee replacements, 16,896 (60.9%) were in women and 10,837 (39.1%) were in men. Metal-backed components were used in 16,011 total knee arthroplasties (57.7%) and all-polyethylene in 11,722 total knee arthroplasties (42.3%). With revision for any reason as the end point, the all-polyethylene tibial component had slightly superior, unadjusted ten-year survival compared with the metal-backed component: 97.2% (95% confidence interval [CI], 96.7% to 97.7%) compared with 96.6% (95% CI, 96.2% to 96.9%; p = 0.002). Cox multiple regression analysis adjusting for age group, sex, and patellar resurfacing showed that all-polyethylene components had a reduced risk of revision for any reason (relative risk = 0.75; 95% CI, 0.64 to 0.89) and a reduced risk of revision due to infection (relative risk = 0.63; 95% CI, 0.46 to 0.86). Patellar resurfacing and male sex increased the risk of revision due to infection (relative risk = 2.22 [95% CI, 1.37 to 3.62] and 2.21 [95% CI, 1.66 to 2.94], respectively). These all-polyethylene tibial components were at least as good as or superior to metal-backed tibial components with respect to implant survivorship at ten years in cruciate-retaining total knee replacements. We concluded that these less expensive all-polyethylene tibial components can be safely and effectively used in total knee arthroplasty. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

A flat all-polyethylene tibial component in medial unicompartmental knee arthroplasty: a long-term study

The aim of this study is to present the clinical and radiological results of a cemented unicompartmental knee arthroplasty (UKA) using a flat all-polyethylene tibial component at long-term follow-up, in a homogeneous group of patients with medial femoro-tibial knee arthritis. The study group included 53 knees in 51 patients who were treated between January 1998 and November 1999 using a flat all-polyethylene tibial component. The same surgical technique was used for all patients. Inclusion criteria included a diagnosis of atraumatic arthritis, pre-operative flexion greater than 100° with no flexion deformity, a varus deformity of less than 10°, and a body mass index (BMI) less than 35. A neutral mechanical axis was considered the end-point in all interventions. The patients were assessed clinically using the International Knee Society (IKS) and the functional scores at follow-up. Plain radiographs were used to determine the alignment of the mechanical axis at 5, 10 and 14.7-year follow-up. A radiographic analysis of loosening, based on the method described by the IKS, was performed and the degree of arthritic progression in the non-resurfaced compartment was also assessed. At latest follow-up five patients had died and the data for three patients had not been collected. At final review four knees had undergone revision surgery and a further patient had declined a recommended revision TKA. The main indication for revision surgery was progressive aseptic loosening of the tibial component in female patients. No revisions were required because of arthritic progression in the lateral compartment. Over time the clinical outcomes did not show statistically significant differences. There was a significant worsening of the mechanical axis at the last follow-up compared with the results at five and ten year review. This study demonstrated that, in primary arthritis involving the medial femoro-tibial compartment, UKA using a flat all-polyethylene component could be considered an effective surgical option. Attention should be paid to progressive worsening of the mechanical axis over time associated with progressive radiolucency especially in female patients. IV.

Design Evolution of the Glenoid Component in Total Shoulder Arthroplasty.

In the early 1970s, Dr. Charles Neer introduced the first glenoid component. The final design was an all-polyethylene component that was keeled and cemented, with conforming humeral and glenoid radii of curvature. In 1982, Dr. Neer was the first author to report successful pain control following total shoulder replacement surgery1. Glenoid replacement has improved patient satisfaction, pain control, and clinical outcomes (Fig. 1)2,3. However, to this day, there remains concern regarding the longevity of the glenoid component, which may be considered the weak link of a total shoulder replacement. Glenoid loosening has been reported as the most common reason for revision total shoulder replacement4-8. In one series, forty-four (59%) of seventy-four failed total shoulder arthroplasties were associated with unstable glenoid components9. Fig. 1 Preoperative and postoperative radiographs of the shoulder of a patient with osteoarthritis and posterior subluxation that were treated with total shoulder arthroplasty. The detection of radiolucent lines surrounding the glenoid component has been used as an indication of glenoid component failure. Radiolucent lines surrounding a glenoid component have been reported as early as immediately postoperatively, with the reported prevalence increasing over time to as high as 90%6,8,10,11. However, the correlation of radiolucent lines with clinical loosening is uncertain, and the rate of revision due to loss of fixation has only been reported to be between 0% to 7%4,7, …

Computed tomography quantification of bone density adjacent to cemented pegged polyethylene glenoid components in shoulder arthroplasty

Cemented polyethylene devices are the prostheses implanted more frequently, but there is no agreement on the optimal glenoid component design. In this study, bone mineral density (BMD) adjacent to cemented all-polyethylene glenoid components was assessed to gain insights into the characteristics of glenoid bone as a potential risk factor implicated in the failure of shoulder arthroplasty. Twenty-two subjects were examined at an average follow-up of 31 months using the Constant-Murley score (CS) and multi-detector computed tomography. BMD was measured in 5 regions of interest (ROIs) at the sites where radiolucent lines are usually detected. BMD differences among the ROIs were tested. The relationship between BMD and a number of variables (CS subscores, age, gender, follow-up duration) was explored. There was a significant increase in CS scores (p<0.05). Significantly different BMD (p=0.0039) was found in the 5 ROIs, especially between ROIs 2 and 5 (p=0.016, Bonferroni's test) and between ROIs 3 and 5 (p=0.005, Bonferroni's test). BMD was lower in ROI 1 than ROI 3 and in ROI 2 than ROI 4, but the difference was not significant. The heterogeneous BMD distribution may be related to: (1) an interindividual variability in glenoid BMD; (2) the fixation technique; or (3) the different bone response to eccentric loading of the prosthetic head on the glenoid component. BMD analysis may contribute to extent our knowledge on glenoid component loosening and encourage further techniques of glenoid fixation.

Bone remodelling of the scapula after a total shoulder arthroplasty

According to Wolff's law, the changes in stress after a prosthesis implantation may modify the shape and internal structure of bone, thus compromising the long-term prosthesis fixation and, consequently, be a significant factor for glenoid loosening. The aim of the present study is to evaluate the changes in the bone adaptation process of the scapula after an anatomical and reverse total shoulder arthroplasty. Five finite element models of the implanted scapula are developed considering the implantation of three anatomical, cemented, all-polyethylene components; an anatomical, cementless, metal-backed component; and a reverse, all-metal component. The methodology followed to simulate the bone adaptation of the scapula was previously validated for the intact model, prior to the prosthesis implantation. Additionally, the influence of the bone quality on the adaptation process is also investigated by considering an osteoporotic condition. The results show that the stress shielding phenomenon is more concerning in cementless, metal-based components than in cemented, all-polyethylene components, regardless of the bone quality. Consequently, as far as the bone adaptation process of the bone is concerned, cemented, all-polyethylene components are better suited for the treatment of the shoulder joint.

Fully uncemented glenoid component in total shoulder arthroplasty

Loosening of the glenoid component remains the most common problem in total shoulder arthroplasty. It has been described that the round-backed, all-polyethylene components with cemented peg fixation perform better biomechanically and clinically than flat-backed, metal-backed, or keeled components. However, side effects of cementing have been described. We hypothesized that cementing of a specific type of all-polyethylene glenoid component with 3 peripheral pegs and 1 central anchor peg is not necessary to obtain good clinical and radiologic results. Thirty-four shoulders (34 patients), with a mean follow-up of 28.3 months, were evaluated clinically with the Constant-Murley score and the SF-12 Health Survey score. The fixation of the glenoid component was evaluated with computed tomography scan. The Constant-Murley score increased from 40.2 points (range, 13-73 points) preoperatively to 72points (range, 54-93 points) postoperatively. The SF-12 Physical Component Summary score was 45, and the SF-12 Mental Component Summary score was 50. No signs of loosening were seen around the pegs or glenoid in 30 shoulders. Signs of loosening were seen around the central anchor peg and the peripheral pegs in 4 shoulders. There was no statistical difference between the clinical outcome of patients with and without signs of loosening. The clinical and radiologic evaluation of an uncemented all-polyethylene glenoid is promising, with good clinical results and with no signs of loosening in 88% of the patients on computed tomography scans.

Cemented polyethylene and cementless porous-coated acetabular components have similar outcomes at a mean of seven years after total hip replacement

The aim of this prospective randomised study was to compare the clinical and radiological results of a cemented all-polyethylene Ultima acetabular component with those of a cementless porous-coated acetabular component (PFC) following total hip replacement (THR). A total of 287 patients received either a polyethylene acetabular component (groupA) or a cobalt-chromium porous-coated component (group B) with an identical cemented femoral component and 28 mm cobalt-chromium head, thus making it the largest study of its type. Patients were evaluated radiologically and clinically using the Harris hip score (HHS). Group A comprised 183 patients (73 male, 110 female) with a mean age of 71.3 years (55 to 89). Group B comprised 104 patients (48 male, 56 female) with a mean age of 69.8 years (56 to 89). A total of 16 patients (13 in Group A, three in Group B) did not have post-operative data for analysis. The mean follow-up in group A was 7.52 years (0.4 to 15.0) and in Group B 7.87 years (0.5 to 14.0). At final follow-up the mean HHS was similar between groups A and B (74.5 (25 to 100) and 78.0 (37 to 100), respectively; p = 0.068). The total number of revisions for any cause was 28, 17 of which were in group A and 11 in group B. The ten-year survivorship was 86.8% (95% confidence interval (CI) 78.4 to 92.1) and 89.2% (95% CI 78.3 to 94.8) for groups A and B, respectively (log-rank p-value = 0.938). A total of 20 cemented and two cementless acetabular components had evidence of acetabular radiolucencies or acetabular component migration at last follow-up (p = 0.001). These results indicate that patients with a cemented all-polyethylene and cementless porous-coated polyethylene lined acetabular component have similar long-term clinical outcomes.

All-polyethylene Tibial Components are Equal to Metal-backed Components: Systematic Review and Meta-regression

Less than 1% of all primary TKAs are performed with an all-polyethylene tibial component, although recent studies indicate all-polyethylene tibial components are equal to or better than metal-backed ones. We asked whether the metal-backed tibial component was clinically superior to the all-polyethylene tibial component in primary TKAs regarding revision rates and clinical functioning, and which modifying variables affected the revision rate. We systematically reviewed the literature for clinical studies comparing all-polyethylene and metal-backed tibial components used in primary TKAs in terms of revision rates, clinical scores, and radiologic parameters including radiostereometric analysis (RSA). Meta-regression techniques were used to explore factors modifying the observed effect. Our search yielded 1557 unique references of which 26 articles were included, comprising more than 12,500 TKAs with 231 revisions for any reason. Meta-analysis showed no differences between the all-polyethylene and metal-backed components except for higher migration of the metal-backed components. Meta-regression showed strong evidence that the all-polyethylene design has improved with time compared with the metal-backed design. The all-polyethylene components were equivalent to metal-backed components regarding revision rates and clinical scores. The all-polyethylene components had better fixation (RSA) than the metal-backed components. The belief that metal-backed components are better than all-polyethylene ones seems to be based on studies from earlier TKAs. This might no longer be true for modern TKAs. Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The Acetabular Component in Primary Total Hip Arthroplasty

The cemented all-polyethylene acetabular component has almost completely been replaced by the cementless porous-coated acetabular component. A variety of different designs, incorporating several types of porous coatings, have proven to be reliable and durable. The ability to reposition a cementless cup to optimize component orientation allows the joint replacement surgeon to minimize impingement and maximize component stability. This is essential to prevent dislocation and damage to bearing surface of the acetabular component. Insertion of a hemispherical cementless cup with 1 mm of under-reaming typically allows for secure interference fit, good apposition of the implant to the underlying bone, an insignificant risk of pelvic fracture, and a rare risk of ingrowth failure.

Glenoid Component Design and Fixation in Total Shoulder Arthroplasty

Glenoid component loosening is one of the most common complications of total shoulder arthroplasty. It accounts for poor functional outcome, persistent pain, and increased chance of reoperation. Many factors contribute to this phenomenon, including limited glenoid bone, especially in the setting of erosion characteristic of osteoarthritis and inflammatory arthropathies, and joint-reactive forces inherent to the shoulder joint. A great deal of research has been done in the areas of component design and implantation technique. We advocate careful glenoid preparation and pressurized cementing technique of all-polyethylene pegged or keeled glenoid components with specialized instrumentation in the majority of cases. We have narrower indications for newer, ingrowth tantalum components.

Tibial component designs in primary total knee arthroplasty: should we reconsider all-polyethylene component?

Despite the frequency with which total knee arthroplasties (TKAs) are performed, whether they are best performed using all-polyethylene or metal-backed tibial components remains a controversy. The aim of the present study was to determine the advantages and disadvantages of metal-backed compared with all-polyethylene tibial components during TKAs through an evaluation of current literature. A meta-analysis and systematic review of randomized and non-randomized comparative studies comparing metal-backed with all-polyethylene tibial components during TKAs were performed. The focus of the analysis was on the outcomes of knee score, range of motion (ROM), quality of life, implant alignment, tibial migration, radiolucent line, complication, reoperation, and implant survivorship. A total of 10 randomized/quasi-randomized controlled trials and 13 non-randomized comparative studies assessing 19,767 TKAs were eligible. On the basis of these studies, no significant differences were found between the 2 groups with regard to knee score, ROM, quality of life, complication, and reoperation. The findings indicated that using all-polyethylene tibial components is associated with lower continuous migration rate compared with metal-backed tibial components. Only 13 studies provided adequate data on implant survivorship during intermediate or long-term follow-up. Of these, 9 found that no statistical significance existed between the 2 groups. The other 3 studies found that using all-polyethylene components yielded a higher survival rate than using metal-backed components. Metal-backed tibial components had no obvious advantages over all-polyethylene tibial components in TKAs. However, this finding should be interpreted with caution due to publication bias, low methodological quality of the included studies, and different surgical interventions. Therapeutic study (systematic review and meta-analysis), Level III.

Cemented All-Polyethylene and Metal-Backed Polyethylene Tibial Components Used for Primary Total Knee Arthroplasty

The cost of the implant as part of a total knee arthroplasty accounts for a substantial portion of the costs for the overall procedure: all-polyethylene tibial components cost considerably less than cemented metal-backed tibial components. We performed a systematic review of the literature to determine whether the clinical results of lower-cost all-polyethylene tibial components were comparable with the results of a more expensive metal-backed tibial component. We searched The Cochrane Library, MEDLINE, EMBASE, EBSCO CINAHL, the bibliographies of identified articles, orthopaedic meeting abstracts, health technology assessment web sites, and important orthopaedic journals. This search was performed for the years 1990 to the present. No language restriction was applied. We restricted our search to Level-I studies involving participants who received either an all-polyethylene or a metal-backed tibial implant. The primary outcome measures were durability, function, and adverse events. Two reviewers independently screened the papers for inclusion, assessed trial quality, and extracted data. Effects estimates were pooled with use of fixed and random-effects models of risk ratios, calculated with 95% confidence intervals. Heterogeneity was assessed with the I2 statistic. Forest plots were also generated. Data on 1798 primary total knee implants from twelve studies were analyzed. In all studies, the median or mean age of the participants was greater than sixty-seven years, with a majority of the patients being female. There was no difference between patients managed with an all-polyethylene tibial component and those managed with a metal-backed tibial component in terms of adverse events. There was no significant difference between the two groups in terms of the durability of the implants at two, ten, and fifteen years postoperatively, regardless of the year or how durability was defined (revision or radiographic failure). Finally, with use of a variety of validated measures, there was no difference between the two groups in terms of functional status at two, eight, and ten years, regardless of the measure used. A less expensive all-polyethylene component as part of a total knee arthroplasty has results equivalent to those obtained with a cemented metal-backed tibial component. Using a total knee implant with a cemented all-polyethylene tibial component could save the healthcare system substantial money while obtaining equivalent results to more expensive cemented designs and materials.

All-polyethylene Tibial Components in Modern Total Knee Arthroplasty

Most total knee arthroplasty prostheses have modular tibial components with metal-backed tibial baseplates. Biomechanical studies have demonstrated mechanical advantages to a metal-backed tibial component in terms of tibial load transfer. In addition, tibial component modularity provides intraoperative flexibility and may provide an advantage in the setting of subsequent revision knee surgery. However, clinical evidence does not support the preferential use of metal-backed tibial components. Modularity introduces the potential for backside wear and associated osteolysis. Also, several recent studies have shown no significant differences in clinical and radiographic outcomes between metal-backed and all-polyethylene tibial components. In addition, all-polyethylene tibial components are less expensive than metal-backed components; increased usage of all-polyethylene components could help decrease the cost of health care.

Total Shoulder Arthroplasty: Tried and True

Total shoulder arthroplasty (TSA) is a reliable procedure to treat primary osteoarthritis of the shoulder. The purpose of this review is to highlight the important discoveries regarding TSA, underscore its longevity, and compare its results with alternative reconstructive options. When comparing the results of TSA to hemiarthroplasty for osteoarthritis and rheumatoid arthritis, the authors of numerous well-designed studies have found TSA to provide superior pain relief, function, and long-term survival. Cemented all-polyethylene glenoid components have excellent long-term survival, whereas metal-backed glenoid components have shown high rates of failure. TSA has stood the test of time and remains the gold standard treatment for glenohumeral arthritis.

Mid-term results of a metal-backed glenoid component in total shoulder replacement

Total shoulder replacement is a successful procedure for degenerative or some inflammatory diseases of the shoulder. However, fixation of the glenoid seems to be the main weakness with a high rate of loosening. The results using all-polyethylene components have been better than those using metal-backed components. We describe our experience with 35 consecutive total shoulder replacements using a new metal-backed glenoid component with a mean follow-up of 75.4 months (48 to 154). Our implant differs from others because of its mechanism of fixation. It has a convex metal-backed bone interface and the main stabilising factor is a large hollow central peg. The patients were evaluated with standard radiographs and with the Constant Score, the Simple Shoulder Test and a visual analogue scale. All the scores improved and there was no loosening, no polyethylene-glenoid disassembly and no other implant-related complications. We conclude that a metal-backed glenoid component is a good option in total shoulder replacement with no worse results than of those using a cemented all-polyethylene prosthesis.