Rates of radiolucency and loosening after total shoulder arthroplasty with pegged or keeled glenoid components

Recent Advances in the Design and Application of Shoulder Arthroplasty Implant Systems and Their Impact on Clinical Outcomes: A Comprehensive Review

Purpose of Review

This narrative review comprehensively aims to analyze recent advancements in shoulder arthroplasty, focusing on implant systems and their impact on patient outcomes. The purpose is to provide a nuanced understanding of the evolving landscape in shoulder arthroplasty, incorporating scientific, regulatory, and ethical dimensions.

Recent Findings

The review synthesizes recent literature on stemless implants, augmented glenoid components, inlay vs onlay configurations, convertible stems, and associated complications. Notable findings include improved patient-reported outcomes with stemless implants, variations in outcomes between inlay and onlay configurations, and the potential advantages of convertible stems. Additionally, the regulatory landscape, particularly the FDA's 510(k) pathway, is explored alongside ethical considerations, emphasizing the need for standardized international regulations.

Summary

Recent innovations in shoulder arthroplasty showcase promising advancements, with stemless implants demonstrating improved patient outcomes. The review underscores the necessity for ongoing research to address unresolved aspects and highlights the importance of a standardized regulatory framework to ensure patient safety globally. The synthesis of recent findings contributes to a comprehensive understanding of the current state of shoulder arthroplasty, guiding future research and clinical practices.

Effect of vitamin E-enhanced highly cross-linked polyethylene on wear rate and particle debris in anatomic total shoulder arthroplasty: a biomechanical comparison to ultrahigh-molecular-weight polyethylene

BACKGROUND

Particle-induced osteolysis resulting from polyethylene wear remains a source of implant failure in anatomic total shoulder designs. Modern polyethylene components are irradiated in an oxygen-free environment to induce cross-linking, but reducing the resulting free radicals with melting or heat annealing can compromise the component's mechanical properties. Vitamin E has been introduced as an adjuvant to thermal treatments. Anatomic shoulder arthroplasty models with a ceramic head component have demonstrated that vitamin E-enhanced polyethylene show improved wear compared with highly cross-linked polyethylene (HXLPE). This study aimed to assess the biomechanical wear properties and particle size characteristics of a novel vitamin E-enhanced highly cross-linked polyethylene (VEXPE) glenoid compared to a conventional ultrahigh-molecular-weight polyethylene (UHMWPE) glenoid against a cobalt chromium molybdenum (CoCrMo) head component.

METHODS

Biomechanical wear testing was performed to compare the VEXPE glenoid to UHMWPE glenoid with regard to pristine polyethylene wear and abrasive endurance against a polished CoCrMo alloy humeral head in an anatomic shoulder wear-simulation model. Cumulative mass loss (milligrams) was recorded, and wear rate calculated (milligrams per megacycle [Mc]). Under pristine wear conditions, particle analysis was performed, and functional biologic activity (FBA) was calculated to estimate particle debris osteolytic potential. In addition, 95% confidence intervals for all testing conditions were calculated.

RESULTS

The average pristine wear rate was statistically significantly lower for the VEXPE glenoid compared with the HXLPE glenoid (0.81 ± 0.64 mg/Mc vs. 7.00 ± 0.45 mg/Mc) (P < .05). Under abrasive wear conditions, the VEXPE glenoid had a statistically significant lower average wear rate compared with the UHMWPE glenoid comparator device (18.93 ± 5.80 mg/Mc vs. 40.47 ± 2.63 mg/Mc) (P < .05). The VEXPE glenoid demonstrated a statistically significant improvement in FBA compared with the HXLPE glenoid (0.21 ± 0.21 vs. 1.54 ± 0.49 (P < .05).

CONCLUSIONS

A new anatomic glenoid component with VEXPE demonstrated significantly improved pristine and abrasive wear properties with lower osteolytic particle debris potential compared with a conventional UHMWPE glenoid component. Vitamin E-enhanced polyethylene shows early promise in shoulder arthroplasty components. Long-term clinical and radiographic investigation needs to be performed to verify if these biomechanical wear properties translate to diminished long-term wear, osteolysis, and loosening.

Imaging in shoulder arthroplasty: Current applications and future perspectives

Shoulder arthroplasty has become a standard surgical procedure for treating a variety of complex shoulder disorders, including those with degenerative and traumatic aetiologies. The ever-improving success rates of shoulder arthroplasty could be attributed to advancements in endoprosthesis design, improvements in the biomechanics of endoprosthetic components, and improvements in surgical techniques. It improves patient outcomes and helps restore shoulder joint function and mobility. Imaging plays a vital role by enabling surgeons to plan arthroplasty procedures, help guide endoprosthesis placement, and monitor postoperative outcomes. In addition, imaging plays a role in assessing the residual bone stock and status of rotator cuff integrity and in correcting the placement of prosthetic components to restore shoulder mobility. CT-guided navigation aids surgeons by helping them choose appropriate components for implants and ensuring that implants are placed optimally during surgery. It can lead to better surgical results with reduced patient morbidity and a longer duration of prosthetic stability. After surgery, it is crucial to use imaging techniques to detect issues such as periprosthetic loosening, infections, or fractures to start effective management strategies to enhance patient recovery. This article aims to provide orthopaedic surgeons and radiologists with knowledge on the imaging methods used in shoulder arthroplasty and their role in presurgical planning, intraoperative guidance and postoperative assessment. In this study, we aimed to investigate the rationale behind utilising various types of shoulder replacements: total shoulder replacement (TSA), reverse total shoulder arthroplasty (RTSA), and hemiarthroplasty; methods, their respective advantages and limitations; and outcomes. Our objective is to comprehensively analyse the procedures mentioned above and highlight their unique features and benefits to facilitate a better understanding of these approaches. Additionally, we will discuss how these imaging techniques help identify issues such as loose components, fractures around the implant site, joint instability and infections.

Comparison of long-term clinical and radiological outcomes for cemented keel, cemented peg, and hybrid cage glenoids with anatomical total shoulder arthroplasty using the same humeral component

Aims

The aim of this study was to longitudinally compare the clinical and radiological outcomes of anatomical total shoulder arthroplasty (aTSA) up to long-term follow-up, when using cemented keel, cemented peg, and hybrid cage peg glenoid components and the same humeral system.

Methods

We retrospectively analyzed a multicentre, international clinical database of a single platform shoulder system to compare the short-, mid-, and long-term clinical outcomes associated with three designs of aTSA glenoid components: 294 cemented keel, 527 cemented peg, and 981 hybrid cage glenoids. Outcomes were evaluated at 4,746 postoperative timepoints for 1,802 primary aTSA, with a mean follow-up of 65 months (24 to 217).

Results

Relative to their preoperative condition, each glenoid cohort had significant improvements in clinical outcomes from two years to ten years after surgery. Patients with cage glenoids had significantly better clinical outcomes, with higher patient-reported outcome scores and significantly increased active range of motion, compared with those with keel and peg glenoids. Those with cage glenoids also had significantly fewer complications (keel: 13.3%, peg: 13.1%, cage: 7.4%), revisions (keel: 7.1%, peg 9.7%, cage 3.5%), and aseptic glenoid loosening and failure (keel: 4.7%, peg: 5.8%, cage: 2.5%). Regarding radiological outcomes, 70 patients (11.2%) with cage glenoids had glenoid radiolucent lines (RLLs). The cage glenoid RLL rate was 3.3-times (p < 0.001) less than those with keel glenoids (37.3%) and 4.6-times (p < 0.001) less than those with peg glenoids (51.2%).

Conclusion

These findings show that good long-term clinical and radiological outcomes can be achieved with each of the three aTSA designs of glenoid component analyzed in this study. However, there were some differences in clinical and radiological outcomes: generally, cage glenoids performed best, followed by cemented keel glenoids, and finally cemented peg glenoids.

A comparison of pegged and keeled glenoid clinical outcomes at long-term follow-up after total shoulder arthroplasty

Background

The two main glenoid types used in total shoulder arthroplasty (TSA) are the pegged and keeled glenoid designs. We aimed to determine if a pegged glenoid is superior to a keeled glenoid at long-term follow-up as measured by range of motion (ROM), patient reported outcomes (PROs), and radiographic glenoid loosening.

Methods

We retrospectively reviewed all patients undergoing TSA by a single surgeon at an urban, academic hospital. The cohort was stratified into two groups based on glenoid type - one group consisting of keeled implants and a second group consisting of pegged implants. For each patient, forward elevation (FE), internal rotation (IR), external rotation (ER), visual analog scale (VAS), American Shoulder and Elbow Surgeons (ASES) shoulder score, and simple shoulder test (SST) scores were collected preoperatively and at the most recent follow-up visit. Radiographic variables included acromiohumeral interval (AHI) and glenoid loosening.

Results

After applying exclusion criteria, 144 TSAs were included in our study. Of these, 42 (29.2%) had keeled glenoids and 102 (70.8%) had pegged glenoids. Patients with a pegged glenoid implant were older (67.4 vs. 60.7 years; p < 0.001) and had a shorter follow-up time (9.3 vs. 14.4 years; p < 0.001) than patients with a keeled glenoid implant. At the most recent follow-up visit, there were no significant differences among postoperative FE, ER, AHI, or PROs. However, pegged glenoid implants provided significantly more internal rotation (T11 vs. L1; p = 0.010) and were less likely to show evidence of radiographic glenoid loosening (16.7% vs. 42.9%; p=<0.001). Revision rates were not significantly different between the pegged and keeled groups (6.9% vs. 14.3%; p = 0.158).

Conclusion

Although a pegged design correlated with superior internal rotation and less radiographic glenoid loosening, both pegged and keeled glenoid designs offered favorable long-term clinical outcomes following TSA over the long-term.

Innovations in Shoulder Arthroplasty

Innovations currently available with anatomic total shoulder arthroplasty include shorter stem designs and augmented/inset/inlay glenoid components. Regarding reverse shoulder arthroplasty (RSA), metal augmentation, including custom augments, on both the glenoid and humeral side have expanded indications in cases of bone loss. In the setting of revision arthroplasty, humeral options include convertible stems and newer tools to improve humeral implant removal. New strategies for treatment and surgical techniques have been developed for recalcitrant shoulder instability, acromial fractures, and infections after RSA. Finally, computer planning, navigation, PSI, and augmented reality are imaging options now available that have redefined preoperative planning and indications as well intraoperative component placement. This review covers many of the innovations in the realm of shoulder arthroplasty.

Prosthetic Bearing Surfaces in Anatomic and Reverse Total Shoulder Arthroplasty

Total shoulder arthroplasty (TSA) and reverse TSA have provided an effective treatment for glenohumeral osteoarthritis; however, longevity of the procedure may be limited by osteolysis and polyethylene wear. In TSA, glenoid component failure occurs through several mechanisms, the most common being aseptic loosening and polyethylene wear. Newer bearing surfaces such as highly cross-linked ultra-high-molecular-weight polyethylene, vitamin E processing, ceramic heads, and pyrolytic carbon surfaces have shown improved wear characteristics in biomechanical and some early clinical studies. The purpose of this review is to provide a historical perspective and current state of the art of bearing surface technology in anatomic and reverse TSA.

Medium-Term Clinical and Radiographic Results of an All-Polyethylene, Pegged, Bone-Ingrowth Glenoid Component: A Concise Follow-up of a Previous Report

ABSTRACT

We previously reported the mean 4-year outcomes of anatomic total shoulder replacement using an all-polyethylene, pegged, hybrid-fixation (bone ingrowth and cement) glenoid component. In the present study, we report on that patient cohort after another 4 years of follow-up (mean, 101 months; range, 77 to 146 months). At that time, the median American Shoulder and Elbow Surgeons (ASES) score was 92 points (interquartile range [IQR], 81.7 to 98.3) and the median Oxford Shoulder Score was 47 points (IQR, 41 to 48). Osseointegration, demonstrated by bone ingrowth between the flanges on the central peg as seen on coronal computed tomography (CT), was complete in 75% of the shoulders, partial in 21%, and absent in 4%. There were radiolucent lines at the bone-prosthesis interface on CT, with a median Yian score of 1 (IQR, 0 to 2; range, 0 to 18). The conclusion in the present study was that shoulder arthroplasty with an all-polyethylene, hybrid-fixation (bone ingrowth and cement) pegged glenoid component has durable clinical and radiographic outcomes at medium-term follow-up.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Short-term rates of radiolucency after primary total shoulder arthroplasty using a cementless metal-backed pegged polyethylene glenoid

BACKGROUND

Total shoulder arthroplasty has shown good clinical efficacy in treating primary and secondary degenerative conditions of the glenohumeral joint. Glenoid loosening, however, remains the commonest cause of failure. The purpose of this study was to investigate the rate of radiographic periprosthetic lucency associated with the use of an uncemented, pegged, metal-backed polyethylene glenoid component.

MATERIALS AND METHODS

A retrospective, single-centre study using the Epoca (Synthes, Paoli, Pennsylvania) metal-backed glenoid component. Operations were performed by two experienced consultant upper limb surgeons. Radiographs were analysed for immediate post-operative component seating and periprosthetic radiolucent lines at predefined regular post-operative intervals. Intra- and inter-observer reliability was assessed to improve validity of results.

RESULTS

Mean age and follow-up was 72 (48-91) years and 2.5 years (2-5), respectively. Main indications for total shoulder arthroplasty were primary osteoarthritis, rheumatoid arthritis, revision for failed hemi-arthroplasty and acute fracture. Ninety-six per cent of components were completely seated post-operatively. Fifty-four (95%) of the 57 shoulders had no periprosthetic radiolucent lines at most recent follow-up. Complete post-operative glenoid seating was significantly associated with the absence of later periprosthetic radiolucency (p < 0.01).

CONCLUSION

This study reports low early radiolucency rates with the pegged, uncemented, metal-backed polyethylene glenoid prosthesis used. Excellent post-operative glenoid seating is associated with a significantly lower rate of radiolucency. Longer follow-up data are required to confirm these early promising results.Level of evidence: Therapeutic, level IV.

Clinical and radiographic outcomes of an all-polyethylene fluted central peg glenoid component, implanted utilizing an off-label, uncemented technique, at a minimum 5-year follow-up

BACKGROUND

Glenoid component loosening remains an important concern in anatomic total shoulder arthroplasty. The aim of this study was to evaluate the clinical and radiographic results of a fully uncemented all-polyethylene fluted central peg bone-ingrowth glenoid component at a minimum 5-year follow-up.

METHODS

Thirty-five shoulders in 31 patients (mean age, 73 years) with a mean follow-up of 100 months were retrospectively evaluated at an early and mid-term time point for Constant score (CS). Computed tomography visualized glenoid component fixation at both time points.

RESULTS

Mean CS improved from 40 preoperatively to 66 postoperatively at latest follow-up (P < .001). A mean CS of 74 at early follow-up remained consistent with a mean CS of 66 at latest follow-up (P = .158), with only strength demonstrating a decrease over time (P < .001). An initial osseointegration rate of 81% at early follow-up decreased to 71% at latest follow-up with 74% of the shoulders demonstrating progressive radiolucent lines, resulting in a radiographic loosening rate of 31%. Of the 35 shoulders, 4 were revised (survival rate of 88%), of which 2 due to symptomatic aseptic loosening.

CONCLUSIONS

Uncemented fixation of an all-polyethylene central peg bone-ingrowth glenoid was associated with satisfactory clinical and radiographic scores, and an acceptable revision rate at mid- to long-term follow-up. Despite initial bony osseointegration in the majority of cases, radiographic loosening over time remains a concern, potentially jeopardizing long-lasting fixation of this type of glenoid component when implanted in an off-label uncemented fashion.

The association between glenoid component design and revision risk in anatomic total shoulder arthroplasty

INTRODUCTION

Anatomic total shoulder arthroplasty (TSA) is a proven treatment for glenohumeral joint osteoarthritis, with superior results compared with hemiarthroplasty. However, glenoid component loosening remains a problem and is one of the most common causes of failure in TSA. Multiple component designs have been developed in an attempt to reduce loosening rates. The purpose of this study was to evaluate risk of revision after anatomic TSA according to the glenoid component design.

METHODS

We conducted a cohort study including patients aged ≥18 years who underwent primary elective TSA for the diagnosis of osteoarthritis between 2010 and 2017. Patients with missing implant information, who received stemless humeral implants, or who received augmented glenoid implants, were excluded. Glenoid component designs used were categorized into 4 mutually exclusive treatment groups: polyethylene central-pegged ingrowth, polyethylene-metal hybrid, polyethylene all-cemented pegged, and polyethylene cemented keeled. Multivariable competing risk regression was used to evaluate the risk of glenoid loosening as a cause-specific revision by the glenoid component design.

RESULTS

Of the 5566 TSA included in the final cohort, 39.2% of glenoid implants were polyethylene central-pegged ingrowth, 31.1% were polyethylene-metal hybrid, 26.0% were polyethylene all-cemented pegged, and 3.6% were polyethylene cemented keeled. At 6-year final follow-up, 4.1% of TSA were revised for any cause, and 1.4% for glenoid loosening. Compared with the polyethylene central-pegged ingrowth design, no difference in glenoid loosening revision risk was observed for the polyethylene-metal hybrid design (hazard ratio [HR] = 1.15, 95% confidence interval [CI] = 0.42-3.20). However, both the polyethylene all-cemented pegged (HR = 2.48, 95% CI = 1.08-5.66) and polyethylene cemented keeled (HR = 3.84, 95% CI = 1.13-13.00) designs had higher risks for revision due to glenoid loosening.

CONCLUSIONS

We observed glenoid component designs to be associated with differential risks in revision due to glenoid loosening with polyethylene all-cemented pegged glenoids and polyethylene cemented keeled glenoids having higher risks when compared with polyethylene central-pegged ingrowth glenoids. Surgeons may want to consider the glenoid component design when performing anatomic TSA.

Integração óssea e prevalência de linhas radiotransparentes ao redor dos pinos de componentes glenoidais minimamente cimentados na artroplastia total de ombro

Objectives  Glenoid component failure is the main cause of total shoulder arthroplasty (TSA) revision, and component design seems to influence the failure rate. The aim of the present study was to clinically and radiographically (through X-rays and computed tomography scan) evaluate the results of TSA using a minimally cemented glenoid component.

Methods  Total should arthroplasties performed using the minimally cemented Anchor Peg (DuPuy Synthes, Warsaw, IN, USA) glenoid component between 2008 and 2013 were evaluated. University of California at Los Angeles (UCLA) scores were calculated, and standardized plain film and computed tomography images were obtained, at a minimum follow-up of 24 months. The presence of bone between the fins of the central component peg, which indicates its integration, was assessed on the images, as well the presence of radiolucent lines around the glenoid component.

Results  Nineteen shoulders in 17 patients were available for evaluation. According to the UCLA score, clinical results were satisfactory in 74% of cases and fair in 21% of cases. One patient had a poor result. Component integration was found in 58% of patients (total in 42% and partial in 16%). Radiolucent lines were observed in 52% of cases. No relationship was detected between component integration and clinical results.

Conclusion  Satisfactory clinical results were achieved in most patients undergoing TSA using a minimally cemented glenoid component. Radiolucent lines around the glenoid component are common, but do not interfere with the clinical results.

Level of evidence IV; Case series; Treatment study.

Intraoperative Efficiency in Contemporary Total Shoulder Arthroplasty: Is Manual Pressure During Cement Curing Still Necessary With Interference Fit Pegged Glenoids?

INTRODUCTION

No previous data have demonstrated the effect of manual pressure during cement curing on interference-fit glenoid implant fixation in total shoulder arthroplasty. In this study, we examined cement mantle characteristics and implant seating using two different methods of securing an interference-fit glenoid implant with peripheral cemented pegs: a manual pressure technique versus a pressureless technique.

METHODS

Sixteen cadaveric scapulae were harvested, and their glenoids were prepared for component insertion. Glenoids with an interference-fit central peg were cemented into the peripheral holes and fully seated. Two techniques were employed during cement curing: (1) a manual pressure technique (8 glenoids), which used a static 70 N load application to each implant for 10 minutes; and (2) a pressureless technique (8 glenoids), which used no pressure application, and the implant was left to set without intervention. Each glenoid was subsequently imaged using microcomputed tomography and analyzed for differences in cement mantle characteristics and implant seating.

RESULTS

The mean area of cement penetration for the manual pressure technique was not statistically different from the pressureless group (P = .26, valid N = 288). The average implant incongruity after final seating in the manual pressure group was 0.63 mm, compared with 1.0 mm in the pressureless group. A linear mixed effects model with a Kenward-Roger correction was used to compare the two groups, and no significant difference was found (Mdiff = -0.386, 95% confidence interval: -0.978 to 0.206; P = 0.17).

CONCLUSION

Manual pressure of the glenoid component during cement curing yielded no difference in the cement mantle area or final implant seating incongruity compared with a pressureless technique. This knowledge could potentially benefit both the surgeon and the patient by increasing the efficiency in total shoulder arthroplasty surgery.

Shoulder replacement surgery for osteoarthritis and rotator cuff tear arthropathy

BACKGROUND

Shoulder replacement surgery is an established treatment for patients with end-stage glenohumeral osteoarthritis or rotator cuff tear arthropathy who have not improved with non-operative treatment. Different types of shoulder replacement are commonly used, but their relative benefits and risks compared versus one another and versus other treatments are uncertain. This expanded scope review is an update of a Cochrane Review first published in 2010.

OBJECTIVES

To determine the benefits and harms of shoulder replacement surgery in adults with osteoarthritis (OA) of the shoulder, including rotator cuff tear arthropathy (RCTA).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, CINAHL, SportDiscus, and Web of Science up to January 2019. We also searched clinical trial registers, conference proceedings, and reference lists from previous systematic reviews and included studies.

SELECTION CRITERIA

We included randomised studies comparing any type of shoulder replacement surgery versus any other surgical or non-surgical treatment, no treatment, or placebo. We also included randomised studies comparing any type of shoulder replacement or technique versus another. Study participants were adults with osteoarthritis of the glenohumeral joint or rotator cuff tear arthropathy. We assessed the following major outcomes: pain, function, participant-rated global assessment of treatment success, quality of life, adverse events, serious adverse events, and risk of revision or re-operation or treatment failure.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. We collected trial data on benefits and harms.

MAIN RESULTS

We included 20 studies involving 1083 participants (1105 shoulders). We found five studies comparing one type of shoulder replacement surgery to another type of shoulder replacement surgery, including three studies comparing conventional stemmed total shoulder replacement (TSR) surgery to stemmed humeral hemiarthroplasty. The remaining 15 studies compared one type of shoulder replacement to the same type of replacement performed with a technical modification or a different prosthetic component. We found no studies comparing shoulder replacement surgery to any other type of surgical treatment or to any type of non-surgical treatment. We found no studies comparing reverse total shoulder replacement surgery to any other type of treatment or to any type of replacement. Trial size varied from 16 to 161 participants. Participant mean age ranged from 63 to 81 years. 47% of participants were male. Sixteen trials reported participants with a diagnosis of osteoarthritis and intact rotator cuff tendons. Four trials reported patients with osteoarthritis and a rotator cuff tear or rotator cuff tear arthropathy. All studies were at unclear or high risk of bias for at least two domains, and only one study was free from high risk of bias (included in the main comparison). The most common sources of bias were lack of blinding of participants and assessors, attrition, and major baseline imbalance. Three studies allowed a comparison of conventional stemmed TSR surgery versus stemmed humeral hemiarthroplasty in people with osteoarthritis. At two years, low-quality evidence from two trials (downgraded for bias and imprecision) suggested there may be a small but clinically uncertain improvement in pain and function. On a scale of 0 to 10 (0 is no pain), mean pain was 2.78 points after stemmed humeral hemiarthroplasty and 1.49 points lower (0.1 lower to 2.88 lower) after conventional stemmed TSR. On a scale of 0 to 100 (100 = normal function), the mean function score was 72.8 points after stemmed humeral hemiarthroplasty and 10.57 points higher (2.11 higher to 19.02 higher) after conventional stemmed TSR. There may be no difference in quality of life based on low-quality evidence, downgraded for risk of bias and imprecision. On a scale of 0 to 100 (100 = normal), mean mental quality of life was rated as 57.4 points after stemmed humeral hemiarthroplasty and 1.0 point higher (5.1 lower to 7.1 higher) after conventional stemmed TSR. We are uncertain whether there is any difference in the rate of adverse events or the rate of revision, re-operation, or treatment failure based on very low-quality evidence (downgraded three levels for risk of bias and serious imprecision). The rate of any adverse event following stemmed humeral hemiarthroplasty was 286 per 1000, and following conventional stemmed TSR 143 per 1000, for an absolute difference of 14% fewer events (25% fewer to 21% more). Adverse events included fractures, dislocations, infections, and rotator cuff failure. The rate of revision, re-operation, or treatment failure was 103 per 1000, and following conventional stemmed TSR 77 per 1000, for an absolute difference of 2.6% fewer events (8% fewer to 15% more). Participant-rated global assessment of treatment success was not reported.

AUTHORS' CONCLUSIONS

Although it is an established procedure, no high-quality randomised trials have been conducted to determine whether shoulder replacement might be more effective than other treatments for osteoarthritis or rotator cuff tear arthropathy of the shoulder. We remain uncertain about which type or technique of shoulder replacement surgery is most effective in different situations. When humeral hemiarthroplasty was compared to TSR surgery for osteoarthritis, low-quality evidence led to uncertainty about whether there is a clinically important benefit for patient-reported pain or function and suggested there may be little or no difference in quality of life. Evidence is insufficient to show whether TSR is associated with greater or less risk of harm than humeral hemiarthroplasty. Available randomised studies did not provide sufficient data to reliably inform conclusions about adverse events and harm. Although reverse TSR is now the most commonly performed type of shoulder replacement, we found no studies comparing reverse TSR to any other type of treatment.

Radiographic performance depends on the radial glenohumeral mismatch in total shoulder arthroplasty

BACKGROUND

Optimal radii of curvature of the articulating surfaces of the prosthetic components are factors associated with the longevity of cemented glenoid components in anatomical total shoulder arthroplasty. It was the purpose of this study, to evaluate the radiographic and clinical performance of an anatomical glenoid component of a total shoulder arthroplasty (TSA) with respect to radial mismatch of the glenoid and humeral component.

METHODS

In a retrospective study 75 TSA were analyzed for their clinical and radiographic performance with computed tomography by independent examiners using an established methodology. The study group was divided in two groups, one with mismatch < 4.5 mm (n:52) the others with mismatch ≥4.5 mm (n:23) and analyzed for confounding variables as indication, primary or revision surgery, age, gender, glenoid morphology and implant characteristics.

RESULTS

The mean glenohumeral radial mismatch was 3.4 mm (range 0.5-6.9). At median follow-up of 41 months (range 19-113) radiographic loosening (defined as modified Molé scores ≥6) was present in 7 cases (9.3%). Lucencies around the glenoid pegs (defined as modified Molé score ≥ 1) were present in 34 cases (45%). Radiolucencies were significantly associated with a radial mismatch < 4.5 mm (p = 0.000). The pre- to postoperative improvements in Subjective Shoulder Value and absolute Constant Score were significantly better in the group with a mismatch ≥4.5 mm (p = 0.018, p = 0.014).

CONCLUSION

A lower conformity of the radii of humerus and glenoid seems to improve the loosening performance in TSA. Perhaps cut-off values regarding the recommended mismatch need to be revalued in the future.

Minimum 5-year outcomes of pegged versus keeled all-polyethylene glenoids

Background

Glenoid loosening remains one of the most common concerns at mid- to long-term follow-up after total shoulder arthroplasty (TSA). Pegged and keeled designs have been compared at short-term follow-up, but few studies have compared outcomes at mid-term follow-up. Our purpose was to compare minimum 5-year outcomes of pegged and keeled cemented, all-polyethylene glenoids in TSA. The hypothesis was that no difference in functional outcomes or loosening would be found between the 2 components.

Methods

We performed a multicenter retrospective study of TSAs with either a pegged or keeled cemented glenoid. At a minimum of 5 years postoperatively, functional outcomes and radiographic loosening were compared.

Results

Forty-seven TSAs were available for follow-up, including 20 pegged and 27 keeled components, at a mean of 79 months (range, 60-114 months) postoperatively. Overall, functional outcomes improved in both groups from preoperatively to postoperatively, and no difference was found between the 2 groups. Radiographic glenoid loosening (score ≥ 3) was observed in 9 of 27 keeled glenoids (33.3%) compared with 5 of 20 pegged glenoids (25%) (P = .54). Loosening was associated with lower postoperative forward flexion (P = .026), lower American Shoulder and Elbow Surgeons scores (P = .030), and higher visual analog scale pain scores (P = .007).

Conclusion

Radiographic glenoid loosening of a cemented, all-polyethylene component was associated with decreased functional outcomes at minimum 5-year follow-up of TSAs. However, this study showed no difference in loosening rates between keeled and pegged components.

Does Prolonged Use of Walkers in Shoulder Arthroplasty Patients Lead to Accelerated Failure Rates?

Introduction: The effect of weight-bearing on a shoulder arthroplasty (SA) remains unclear, and recommendations regarding the use of a walker in SA patients have not been established. The purpose of this study was to determine outcomes and survivorship of SA in patients who routinely use a walker.

Methods: Fifty-three primary SA (10 hemiarthroplasties (HAs), 33 anatomic total shoulder arthroplasties (TSAs), 10 reverse shoulder arthroplasties (RSAs)) in 41 walker-dependent patients were followed for a minimum of three years (mean 64 months, range, 36-156). The average age at SA was 76 years. Shoulders were assessed for pain, range of motion (ROM), satisfaction, Neer ratings, American Shoulder and Elbow Surgeons (ASES) score, complications, survivorship, and radiographic outcomes.

Results: At most recent follow-up, 40 shoulders (75%) were pain free, elevation and external rotation improved significantly (P < .0001), and 87% of the patients were satisfied. Postoperative ASES scores averaged 74 (range, 38-92) points. There were 25 excellent, 16 satisfactory, and 12 unsatisfactory results based on modified Neer ratings. Four shoulders (7.5%) required reoperation at a mean of 40 months after the index arthroplasty. Radiographically, there were six cases of glenoid loosening in the anatomic SA group (25%), and two cases of severe glenoid erosion in the HA group (25%).

Conclusion: Routine use of a walker does not appear to lead to a markedly increased rate of SA failure at mid-term follow-up. Concerning radiographic findings were more common after HA and anatomic TSA than after RSA. Longer follow-up is required to determine the long-term impact of walker use on SA.

Imaging of shoulder arthroplasties and their complications: a pictorial review

Currently, an increasing number of patients benefit from shoulder prosthesis implantation. Radiologists are therefore more often confronted with imaging examinations involving shoulder arthroplasty, whether during a dedicated examination or incidentally. Standard radiography is the first-line imaging modality in the follow-up of these implants, before the possible use of cross-sectional imaging modalities (computed tomography and magnetic resonance imaging), ultrasound, or nuclear medicine examinations. Shoulder arthroplasties are divided into three categories: reverse shoulder arthroplasty, total shoulder arthroplasty, and partial shoulder joint replacement (including humeral hemiarthroplasty and humeral head resurfacing arthroplasty). Each of these prostheses can present complications, either shared by all types of arthroplasty or specific to each. Infection, periprosthetic fractures, humeral component loosening, heterotopic ossification, implant failure, and nerve injury can affect all types of prostheses. Instability, scapular notching, and acromial fractures can be identified after reverse shoulder arthroplasty implantation. Glenoid component loosening and rotator cuff tear are specific complications of total shoulder arthroplasty. Progressive wear of the native glenoid is the only specific complication observed in partial shoulder joint replacement. Knowledge of different types of shoulder prostheses and their complications’ radiological signs is crucial for the radiologist to initiate prompt and adequate management.

The effect of vitamin E-enhanced cross-linked polyethylene on wear in shoulder arthroplasty-a wear simulator study

BACKGROUND

Wear of the polyethylene glenoid component and subsequent particle-induced osteolysis remains one of the most important modes of failure of total shoulder arthroplasty. Vitamin E is added to polyethylene to act as an antioxidant to stabilize free radicals that exist as a byproduct of irradiation used to induce cross-linking. This study was performed to assess the in vitro performance of vitamin E-enhanced polyethylene compared with conventional polyethylene in a shoulder simulator model.

METHODS

Vitamin E-enhanced, highly cross-linked glenoid components were compared with conventional ultrahigh-molecular-weight polyethylene glenoids, both articulating with a ceramic humeral head component using a shoulder joint simulator over 500,000 cycles. Unaged and artificially aged comparisons were performed. Volumetric wear was assessed by gravimetric measurement, and wear particle analysis was also subsequently performed.

RESULTS

Vitamin E-enhanced polyethylene glenoid components were found to have significantly reduced wear rates compared with conventional polyethylene in both unaged (36% reduction) and artificially aged (49% reduction) comparisons. There were no differences detected in wear particle analysis between the 2 groups.

CONCLUSION

Vitamin E-enhanced polyethylene demonstrates improved wear compared with conventional polyethylene in both unaged and artificially aged comparisons and may have clinically relevant benefits.

[Shoulder Osteoarthritis-pathogenesis, classification, diagnostics and treatment]

Primary osteoarthritis of the shoulder represents a destructive joint disease with associated synovitis, which in the first line seems to be genetically determined. Clinically, patients suffer from shoulder pain with progressive impairment of both active and passive range of motion. The diagnostics include a clinical examination, imaging by native radiography and magnetic resonance imaging (MRI) for assessment of the rotator cuff. Current classification systems consider the formation of humeral osteophytes, glenoid morphology and loss of humeral sphericity. Non-surgical measures include, apart from topical and oral analgesics, injection of corticosteroids and hyaluronic acid supported by physiotherapeutic measures. After failure of non-surgical therapeutic measures, arthroscopic joint-preserving arthroplasty in terms of the comprehensive arthroscopic management (CAM) procedure can be performed in young patients with early stage osteoarthritis, whereas in advanced stages endoprosthetic joint replacement is indicated.

Proceedings from the 2018 International Consensus Meeting on Orthopedic Infections: evaluation of periprosthetic shoulder infection

The Second International Consensus Meeting on Orthopedic Infections was held in Philadelphia, Pennsylvania, in July 2018. More than 800 experts from all 9 subspecialties of orthopedic surgery and allied fields of infectious disease, microbiology, and epidemiology were assembled to form the International Consensus Group. The shoulder workgroup reached consensus on 27 questions related to culture techniques, inflammatory markers, and diagnostic criteria used to evaluate patients for periprosthetic shoulder infection. This document contains the group's recommendations and rationale for each question related to evaluating periprosthetic shoulder infection.

Five-year minimum clinical and radiographic outcomes of total shoulder arthroplasty using a hybrid glenoid component with a central porous titanium post

BACKGROUND

To determine the effectiveness of hybrid glenoid components in reducing the frequency of glenoid component loosening, we evaluated clinical and radiographic outcomes at a minimum 5-year follow-up in 45 shoulders that underwent total shoulder arthroplasty (TSA) using a system with a central porous titanium post to augment the cemented peripheral pegs.

METHODS

Function and pain were evaluated with the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment score, visual analog scale, active shoulder range of motion, and strength. Postoperative radiographs were analyzed for radiolucent lines, progressive loosening, and at-risk signs.

RESULTS

The mean American Shoulder and Elbow Surgeons score improved from 40.4 to 83.7 (P < .0001) and the mean visual analog scale from 5.9 to 0.8 (P < .0001). Forward elevation improved from 113° to 151° (P < .001), internal rotation from 49° to 60° (P = .035), and mean external rotation from 36° to 50° (P = .0006). Radiographs showed glenoid component radiolucency in 29 shoulders. Radiolucencies were confined to the area under the glenoid faceplate in 6 and were only around the central post in 13. Nine TSAs (20%) demonstrated 2 or more columns of involvement but were not judged to be at-risk. One implant (2.2%) had glenoid component failure and was revised to a hemiarthroplasty.

CONCLUSION

Anatomic TSA using a hybrid glenoid component with a central porous titanium post demonstrated a low rate of mechanical failure and a rate of radiolucent lines comparable to reports of all polyethylene implants. Further evaluations are needed to demonstrate the long-term durability of these implants and to determine the significance and fate of the radiolucent lines, particularly relative to the central post.

Radiographic comparison of finned, cementless central pegged glenoid component and conventional cemented pegged glenoid component in total shoulder arthroplasty: a prospective randomized study

BACKGROUND

Radiographic lucency of the glenoid component remains a problem after cement fixation in primary total shoulder arthroplasty. Glenoid component design likely contributes to rates of glenoid lucency. The purpose of this study was to prospectively compare radiographic lucency between a finned, cementless central pegged glenoid component (CL component) and a conventional cemented pegged glenoid component (P component) on immediate postoperative and minimum 2-year follow-up radiographs.

METHODS

Fifty-four patients undergoing total shoulder arthroplasty were prospectively randomized to receive an all-polyethylene CL component or a conventional all-polyethylene P component. Three raters graded glenoid lucency and bone interdigitation on immediate postoperative and latest follow-up radiographs. Patients who had undergone revision surgery or had died before evaluation were excluded. Minimum 2-year follow-up was required for inclusion of radiographic evaluation.

RESULTS

Fifty patients met inclusion criteria; 42 patients (84%; 20 CL and 22 P) were available for follow-up with the original glenoid implant in place. The mean follow-up duration was 35 months (24-64 months). There were no significant differences in glenoid radiolucency between CL (1/20 [5%]) and P (2/22 [9%]) components at last follow-up (P = .999). Five patients (25%) in the CL group had bone interdigitation. No instances of aseptic glenoid loosening occurred.

CONCLUSION

There were no significant differences in the rate of glenoid lucency between the 2 groups at immediate or an average 35-month follow-up. Both techniques appear to be viable options for initial glenoid component fixation, with CL components allowing possible osseointegration, imparting potential long-term stability.

Anatomic Total Shoulder Arthroplasty Using a Self-Pressurizing Pegged Bone-Preserving Cemented Glenoid Component: A 2- to 5-Year Follow-up Study

Background:

High rates of radiographic loosening have been reported with various glenoid designs. Many available designs sacrifice most of the bone at the central portion of the glenoid vault, creating large areas of deficiency when revision becomes necessary. The purpose of this study was to report the 2- to 5-year outcome of shoulder arthroplasty using a bone-preserving all-polyethylene glenoid components with self-pressurizing pegs.

Methods:

Between August 2011 and December 2014, 202 consecutive anatomic total shoulder arthroplasties (TSAs) were performed by a single surgeon with implantation of a self-pressurizing cemented pegged glenoid component in 190 patients (12 patients had both shoulders replaced). Patients were followed up prospectively and evaluated for pain, motion, strength, American Shoulder and Elbow Surgeons (ASES) scores, and radiographic changes. The mean follow-up time was 2.7 (2–5) years.

Results:

TSA improved pain and function reliably. At the most recent follow-up, 94% of the shoulders had no or mild pain. Motion included 154 ± 25° of elevation, 68 ± 18° of external rotation, and median internal rotation to T10 (range, iliac crest to T4). The most recent average ASES score was 82 ± 15 points. Early postoperative radiographs showed no radiolucent lines. No humeral or glenoid component was considered radiographically loose at the most recent follow-up. Complications requiring reoperation included subscapularis insufficiency (4), posterior instability (2), deep infection (1), stiffness (1), and a painful loose body (1). No components were revised for loosening.

Conclusions:

Anatomic TSA using a cemented bone-preserving all-polyethylene pegged self-pressurizing glenoid component provided satisfactory clinical outcomes and survival at 2 to 5 years.

Radiographic and clinical comparison of pegged and keeled glenoid components using modern cementing techniques: midterm results of a prospective randomized study

BACKGROUND

Glenoid component loosening remains a significant issue after anatomic shoulder arthroplasty. Pegged glenoid components have shown better lucency rates than keeled components in the short term; however, midterm to long-term results have not fully been determined. We previously reported early outcomes of the current randomized controlled group of patients, with higher glenoid lucency rates in those with a keeled glenoid. The purpose of this study was to evaluate the radiographic and clinical outcomes of these components at minimum 5-year follow-up.

METHODS

Fifty-nine total shoulder arthroplasties were performed in patients with primary glenohumeral osteoarthritis. Patients were randomized to receive either a pegged or keeled glenoid component. Three raters graded radiographic glenoid lucencies. Clinical outcome scores and active mobility outcomes were collected preoperatively and at yearly postoperative appointments.

RESULTS

Of the 46 shoulders meeting the inclusion criteria, 38 (82.6%) were available for minimum 5-year radiographic follow-up. After an average of 7.9 years, radiographic lucency was present in 100% of pegged and 91% of keeled components (P = .617). Grade 4 or 5 lucency was present in 44% of pegged and 36% of keeled components (P = .743). There were no differences in clinical outcome scores or active mobility outcomes between shoulders with pegged and keeled components at last follow-up. Within the initial cohort, 20% of the keeled shoulders (6 of 30) and 7% of the pegged shoulders (2 of 29) underwent revision surgery (P = .263). Kaplan-Meier analysis showed no significant difference in survival rates between groups (P = .560).

CONCLUSION

At an average 7.9-year follow-up, non-ingrowth, all-polyethylene pegged glenoid implants are equivalent to keeled implants with respect to radiolucency, clinical outcomes, and need for revision surgery.

Evaluation of thirty eight cemented pegged glenoid components with variable backside curvature: two-year minimum follow-up

BACKGROUND

The PERFORM™ pegged glenoid system has been used for shoulder arthroplasty since 2012. This system offers multiple backside curvatures per size to better match variable patient anatomy. As a result, less reaming is required and subchondral bone is preserved-a critical factor in preventing glenoid migration and loosening, thus enhancing implant longevity.

PURPOSE

The purpose of this study was to analyze all radiographic modifications around this new glenoid implant.

METHOD

Thirty-eight shoulders which received the PERFORM™ pegged glenoid component between June 2012 and January 2014 for primary or secondary osteoarthritis were reviewed at two-years minimum follow-up. There were 13 men and 22 women with an average age of 67 years. Humeral components were an uncemented short stem implant in nine (23%) and a resurfacing implant in 29 (77%).

RESULTS

At 27-months average follow-up (24-41), Constant score improved from 30 to 65 points. Range of motion improved significantly at follow-up from 100° to 142° for the anterior elevation, and from 15 to 40° for the external rotation. Radiographic lucent lines (RLL) were observed post-operatively in eight cases (21%), and in 16 cases (42%) at the last follow-up with an increase of the RLL score from 0.36 ± 0.8 to 1.3 ± 2 (p < 0.001) without signs of loosening (RLL > 12). One revision has been performed after anterior shoulder dislocation, rotator cuff tear and glenoid component migration. RLL score was not correlated with dominant side, sex, age, or Constant score.

DISCUSSION-CONCLUSION

The cemented pegged glenoid component with multiple backside curvatures gave satisfactory results at two-years minimum follow-up for up to three years with a low RLL score. Long-term studies are mandatory to confirm these results.

Stability of two versus three peripheral pegs of the glenoid component in modern total shoulder arthroplasty

PURPOSE

In total shoulder arthroplasty (TSA), the optimum number of peripheral pegs required for stability in the glenoid component is unknown. This study compared the stability of two versus three peripheral pegs in cemented glenoid components possessing a central press-fit peg.

METHODS

Six unmodified glenoid components with three peripheral pegs, a large, central press-fit peg and six modified glenoid components with one inferior peripheral peg sharply removed were cemented into bone substitute polyurethane blocks. A modified rocking-horse test was completed by comparing superior- and inferior-edge displacement before and after 100,000 vertical motion cycles. Then, a torsional failure test applied 2 N axial load, followed by a rotational force to the glenoid component at 0.5 °/s until failure.

RESULTS

Modified rocking-horse testing showed no statistically significant edge displacement at the superior or inferior aspect of the glenoid component before or after testing. During torsional testing, peak torque and degrees of rotation at failure also showed no significant difference.

CONCLUSION

Two peripheral pegs offer equivalent stability as three peripheral pegs, as assessed by cyclic rocking and rotational failure testing. Fewer peripheral pegs during glenoid component implantation may lead to less dissection, less strain on soft tissues and decreased operative time.

Radiostereometric analysis of keeled versus pegged glenoid components in total shoulder arthroplasty: a randomized feasibility study

BACKGROUND

This study aimed to assess differences in the fixation and functional outcomes between pegged and keeled all-polyethylene glenoid components for standard total shoulder arthroplasty.

METHODS

Patients were randomized to receive a keeled or pegged all-polyethylene glenoid component. We used model-based radiostereometric analysis (RSA) to assess glenoid fixation and subjective outcome measures to assess patient function. Follow-up examinations were completed at 6 weeks and 6, 12 and 24 months after surgery. Modifications to the RSA surgical, imaging and analytical techniques were required throughout the study to improve the viability of the data.

RESULTS

Stymied enrolment resulted in only 16 patients being included in our analyses. The RSA data indicated statistically greater coronal plane migration in the keeled glenoid group than in the pegged group at 12 and 24 months. Functional outcome scores did not differ significantly between the groups at any follow-up. One patient with a keeled glenoid showed high component migration after 24 months and subsequently required revision surgery 7 years postoperatively.

CONCLUSION

Despite a small sample size, we found significant differences in migration between glenoid device designs. Although clinically these findings are not robust, we have shown the feasibility of RSA in total shoulder arthroplasty as well as the value of a high-precision metric to achieve objective results in a small group of patients.

A comparison of onlay versus inlay glenoid component loosening in total shoulder arthroplasty

BACKGROUND

Glenoid component loosening is common in total shoulder arthroplasty (TSA), often resulting from the mechanical interaction of glenohumeral components. This cadaveric study was performed to evaluate and to compare commercially available onlay and inlay glenoid prosthetic designs with respect to loading characteristics and loosening.

METHODS

Sixteen prescreened cadaveric shoulders (8 matched pairs) underwent either onlay or inlay TSA. We created a custom glenohumeral loading model and used cycles of 5 mm anterior-posterior humeral translation to simulate a rocking-horse loosening mechanism for all testing. Articular TekScan measurements were performed with 9.1 kg (88.9 N) of glenohumeral compression before and after TSA. Fatigue testing was performed with 34.0 kg (333.6 N) of glenohumeral compression using high-definition video to document gross glenoid loosening. Testing ended with gross loosening or a maximum of 4000 cycles. Mean contact area, pressure, and joint reaction force were used to compare the 2 glenoid designs.

RESULTS

In both implant types, contact area decreased and pressure increased after TSA (P < .0001). Force increased at the onlay component edge only (P = .0012) compared with native glenoid testing. Force was greater in the onlay vs. the inlay implants (P < .0001). During fatigue testing, all onlay glenoid components exhibited gross loosening at a mean of 1126 cycles (range, 749-1838), whereas none of the inlay glenoid components exhibited gross loosening (P < .0001).

CONCLUSION

The inlay glenoid implant exhibited biomechanical characteristics favoring stability and decreased loosening compared with the onlay glenoid implant in this cadaveric model.

The three-dimensional glenohumeral subluxation index in primary osteoarthritis of the shoulder

BACKGROUND

Assessment of glenohumeral subluxation is essential in preoperative planning of total shoulder arthroplasty. The purpose of this study was to evaluate a 3-dimensional (3D) glenohumeral subluxation index (GHSI) in shoulders with primary osteoarthritis (OA) and its relationship with morbid glenoid retroversion.

METHODS

The 3D computed tomography reconstructions of 120 healthy shoulders and 110 shoulders with primary glenohumeral arthritis (OA group), classified according to Walch's glenoid morphology, were analyzed. The 3D GHSI was assessed by measuring posterior decentering of the humeral head in relation to the native glenoid in each subject, and its correlation to morbid glenoid version was calculated.

RESULTS

The reproducible 3D GHSI (intraclass correlation coefficients ≥ 0.842) showed a posterior decentering of the humeral head in the OA population and in each type of glenoid morphology (P ≤ .005). A moderate correlation was observed in the OA group (r = -0.542; P < .001), but weak linear relationships were found for different glenoid morphology types (r between 0.041 and -0.307). Type A shoulders (r = -0.375; P = .006) correlated better than type B shoulders (r =  -0.217; P = .104). After shoulders were subcategorized according to a threshold for 3D subluxation, the posteriorly subluxated group increased its correlation (r = -0.438; P < .001), whereas the centered shoulders still exhibited no relationship (r = -0.192; P = .329).

CONCLUSIONS

Posterior humeral head decentering in relation to the native glenoid is present in each glenoid morphology type. Grouping measures according to morphology type and 3D subluxation showed at best moderate correlations between morbid version and 3D GHSI.

Towards standardised definitions of shoulder arthroplasty complications: a systematic review of terms and definitions

INTRODUCTION

A transparent, reliable and accurate reporting of complications is essential for an evidence-based evaluation of shoulder arthroplasty (SA). We systematically reviewed the literature for terms and definitions related to negative events associated with SA.

MATERIALS AND METHODS

Various biomedical databases were searched for reviews, clinical studies and case reports of complications associated with SA. Any general definition of a complication, classification system, all reported terms related to complications and negative events with their definitions were extracted. Terms were grouped and organised in a hierarchical structure. Definitions of negative events were tabulated and compared.

RESULTS

From 1086 initial references published between 2010 and 2014, 495 full-text papers were reviewed. Five reports provided a general definition of the term "surgical complication" and 29 used a classification system of complications. A total of 1399 extracted terms were grouped based on similarities and involved implant or anatomical parts. One hundred and six reports (21.4%) defined at least one negative event for 28 different terms. There were 64 definitions related to humeral or glenoid loosening, and 25 systems documenting periprosthetic radiolucency. Other definitions considered notching, stress shielding, implant failure and tuberosity malposition.

CONCLUSIONS

A clear standardised set of SA complication definitions is lacking. Few authors reported complications based on definitions mainly considering radiological criteria without clinical parameters. This review should initiate and support the development of a standardised SA complication core set.

A three-dimensional comparative study on the scapulohumeral relationship in normal and osteoarthritic shoulders

BACKGROUND

Eccentric loading due to humeral translation is associated with worse clinical outcomes in hemiarthroplasty and total shoulder arthroplasty. The purpose of this study was to evaluate the 3-dimensional relationship of the humeral head to the scapula (scapulohumeral relationship) in nonpathologic shoulders and in shoulders with primary osteoarthritis.

MATERIALS AND METHODS

Three-dimensional reconstructions of computed tomography scans of 151 nonpathologic shoulders (control group) and 110 shoulders with primary glenohumeral arthritis (OA group) were analyzed by measuring the anterior-posterior, inferior-superior, and medial-lateral position of the humeral head in relation to the scapula. Shoulders were classified as centered (type A) or posteriorly subluxed (type B) according to the Walch classification of glenoid morphology. Reproducibility and differences in scapulohumeral relationship were statistically analyzed.

RESULTS

The scapulohumeral relationship could be determined reliably: the intraclass correlation coefficient ranged between 0.780 and 0.978; the typical error of measurement ranged between 2.4% and 5.0%. Both type A and type B shoulders showed significant posterior translation of the humeral head (P <.001). Type B shoulders had significantly more posterior translation than type A shoulders (P <.001). A tendency of inferior translation was noted, although with only marginal statistical significance (P = .051). In each morphology class, a medial deviation of the humeral head, representing a reduced glenohumeral distance, was measured (P <.001).

CONCLUSIONS

The main characteristics of primary glenohumeral osteoarthritis are posterior humeral head translation relative to the scapula, reduced glenohumeral distance, and a tendency toward inferior humeral head translation in both type A and type B shoulders.

Loose glenoid components in revision shoulder arthroplasty: is there an association with positive cultures?

BACKGROUND

Glenoid loosening is one of the most common causes of total shoulder failure. High rates of positive cultures of Propionibacterium and coagulase-negative staphylococcus have been found among shoulders having surgical revision for glenoid loosening. This study reviewed the culture results in a series of surgical revisions for failed total shoulder arthroplasty to determine the relationship between glenoid loosening and positive cultures.

METHODS

The medical records of 221 patients without obvious evidence of infection who underwent revision total shoulder arthroplasty were reviewed to examine the association between the security of fixation of the glenoid component and the results of cultures obtained at revision surgery.

RESULTS

Of the revised shoulders, 53% had positive cultures; 153 of the shoulders (69%) had a loose glenoid component, whereas 68 (31%) had secure glenoid component fixation. Of the 153 loose glenoid components, 82 (54%) had at least 1 positive culture and 44 (29%) had 2 or more positive cultures of the same microorganism. Similarly, of the 68 secure glenoid components, 35 (51%) had at least 1 positive culture (P = .77) and 14 (21%) had 2 or more positive cultures of the same microorganism (P = .25). Explanted glenoid components that were loose had a higher rate of culture positivity (56% [24/43]) in comparison to explanted glenoid components that were well fixed (13% [1/8]) (P = .05).

CONCLUSION

Propionibacterium and coagulase-negative staphylococcus are commonly recovered in revision shoulder arthroplasty, whether or not the glenoid components are loose.

Clinical and Radiographic Results of an All-Polyethylene Pegged Bone-Ingrowth Glenoid Component

BACKGROUND

Loosening of the glenoid component continues to be the main cause of medium and long-term failure of shoulder replacements. The purpose of this study was to evaluate the early clinical and radiographic results following use of an all-polyethylene pegged glenoid component designed for hybrid (biological and cement) fixation.

METHODS

Eighty-three shoulders in 77 patients (mean age, 68.6 years) underwent total shoulder arthroplasty with a pegged hybrid-fixation component (bone-ingrowth glenoid and cemented peg). Outcomes were determined with the American Shoulder and Elbow Surgeons (ASES) score and the Oxford shoulder score. A detailed analysis of radiographs and fine-slice computed tomography (CT) images was performed to determine the extent of bone ingrowth between the flanges and the extent of radiolucent lines at the prosthesis-bone interface.

RESULTS

The mean duration of follow-up was 46.7 months (range, 24 to 99 months). At the time of final follow-up, the median ASES score was 97 points (range, 43 to 100 points) and the median Oxford score was 48 points (range, 24 to 48 points). The median active forward elevation was 130° (range, 65° to 170°), median external rotation was 45° (range, 5° to 80°), and median internal rotation was to T11 (range, buttock to T4). Seventy-eight shoulders demonstrated a perfect Lazarus score for radiolucency (0, indicating no radiolucency). Sixty-eight shoulders demonstrated complete osseointegration, with bone ingrowth between all of the flanges seen on coronal CT; 5 demonstrated partial osseointegration; and 10 demonstrated osteolysis around the central peg. Most radiolucent lines were in the inferior Yian zones. There were no correlations between the Yian CT scores and either the ASES or Oxford score (rho = 0.13 and 0.07, respectively).

CONCLUSIONS

Total shoulder arthroplasty with an all-polyethylene pegged glenoid component, utilizing hybrid fixation, demonstrated excellent clinical and radiographic results at the time of early follow-up. Radiolucent lines were seen most commonly around the inferior pegs of the prosthesis, and this may represent an incipient mode of failure.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Glenoid cement mantle characterization using micro-computed tomography of three cement application techniques

BACKGROUND

Numerous studies have documented the concern for progressive radiolucent lines, signifying debonding and subsequent aseptic loosening of the glenoid component. In this study, we compared 3 cementation methods to secure a central peg in 15 cadaveric glenoids.

METHODS

Cement application techniques consisted of (1) compression of multiple applications of cement using manual pressure over gauze with an Adson clamp, (2) compression of multiple applications of cement using a pressurizer device, and (3) no compression of a single application of cement. Each glenoid was then imaged with high-resolution micro-computed tomography and further processed by creating 3-dimensional computerized models of implant, bone, and cement geometry. Cement morphology characteristics were then analyzed in each of the models.

RESULTS

There were no significant differences detected between the 2 types of compression techniques; however, there was a significant difference between compression methods and use of no compression at all. All morphologic characteristics of a larger cement mantle were significantly correlated with greater cortical contact.

CONCLUSIONS

We demonstrate that compression techniques create a larger cement mantle. Increased size of the cement mantle is associated with increased contact with cortical bone at the glenoid vault. This method for characterizing the cement mantle by micro-computed tomography scanning techniques and 3-dimensional analysis may also be useful in future finite element analysis studies.

Radiographic and clinical outcomes of total shoulder arthroplasty with an all-polyethylene pegged bone ingrowth glenoid component: prospective short- to medium-term follow-up

BACKGROUND

Glenoid components often cause total shoulder arthroplasty failure. This study examines short-term to midterm radiographic and clinical results of a hybrid glenoid component with 3 cemented peripheral pegs and a central peg, which allows biologic fixation with use of native humeral head autograft.

METHODS

In 4 years, 80 glenoid components were implanted during primary total shoulder arthroplasty with at least 2-year follow-up data. Within 12 months, 4 shoulders were revised and excluded from final analyses. Seven patients did not complete their questionnaires. Outcomes data included the American Shoulder and Elbow Surgeons (ASES) questionnaire, Constant score, and satisfaction score. A shoulder and elbow fellowship-trained surgeon, not involved in the care of these patients, analyzed radiographs for radiolucent lines, glenoid seating, and radiodensity in between the flanges of the central peg.

RESULTS

Only 1 of 80 shoulders was revised for aseptic glenoid loosening. At final follow-up, 81.6% had a radiolucency grade of 0 or 1. Nearly 90% had a glenoid seating grade of A or B. Grade 2 or 3 bone around the central peg was seen in 88.2%. No statistical association existed between Walch glenoid types and radiolucency grades, bone grades around the central peg, perfect radiolucency grade, seating grade, and grade 3 bone around the central peg. There was significant improvement in mean ASES score, adjusted ASES pain score, Constant score, and satisfaction score as well as in forward flexion, abduction, and external rotation.

CONCLUSIONS

The hybrid glenoid can produce stable radiographic and clinical outcomes at short- to medium-term follow-up.

No differences in early results of a hybrid glenoid compared with a pegged implant

BACKGROUND

Glenoid component loosening after total shoulder arthroplasty is one of the most common causes of failure. A hybrid glenoid that uses peripherally cemented pegs and a central press-fit post may improve implant longevity.

QUESTIONS/PURPOSES

We asked, compared with polyethylene pegged glenoid implants, do hybrid glenoid implants with a titanium post provide (1) better ingrowth with fewer radiolucencies, (2) better outcome and pain scores, and (3) lower risk of complications and revisions?

METHODS

Between 2009 and 2010, 126 patients underwent primary total shoulder arthroplasty for osteoarthritis. Patients were included in this retrospective study if they consented for inclusion in a shoulder arthroplasty registry, had complete baseline and 2-year data, and had complete radiographs. Eighty-three (67%) were available at an average followup of 3.2 years (range, 24-45 months). Forty received a conventional all-polyethylene pegged glenoid and 43 received a hybrid component. During the period in question, four of the participating surgeons used only one implant, and four used only the other; there was one high-volume surgeon in each of the study groups. Radiographs were taken at the 2-year followup and analyzed for radiolucent lines. CT scans were obtained randomly for 10 patients with hybrid glenoid implants to assess bone ongrowth. American Shoulder and Elbow Surgeons score, VAS score, complications and revisions were recorded.

RESULTS

At final followup, radiolucent lines between the two study groups were not different (hybrid, 1.0 ± 0.4; pegged, 1.6 ± 0.3; mean difference, 0.6; 95% CI, 0.85-1.72; p = 0.323). Final VAS pain scores were not different (hybrid, 1.2 ± 0.2; pegged, 1.5 ± 0.3; p = 0.056). Change in American Shoulder and Elbow Surgeons scores were not different (hybrid, 33.7 ± 7.3; pegged, 35.5 ± 8.2; p = 0.283). There were no differences in complication risk (hybrid, one of 43 [2.3%]; pegged, three of 40 [7.5%]; relative risk, 2.3; 95% CI, 0.82-3.12; p = 0.061).

CONCLUSIONS

With the numbers available and at early followup, there were no differences between the hybrid and pegged glenoids in terms of fixation, functional outcome, pain scores, and complications. CT scans confirmed bone ongrowth on the porous titanium post in a small subcohort of patients. Further studies are needed to determine how this new implant will perform with time. Until then, its use should be initiated with caution.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Rocking-horse phenomenon of the glenoid component: the importance of inclination

BACKGROUND

Abnormal glenoid version positioning has been recognized as a cause of glenoid component failure caused by the rocking horse phenomenon. In contrast, the importance of the glenoid inclination has not been investigated.

MATERIALS AND METHODS

The computed tomography scans of 152 healthy shoulders were evaluated. A virtual glenoid component was positioned in 2 different planes: the maximum circular plane (MCP) and the inferior circle plane (ICP). The MCP was defined by the best fitting circle of the most superior point of the glenoid and 2 points at the lower glenoid rim. The ICP was defined by the best fitting circle on the rim of the inferior quadrants. The inclination of both planes was measured as the intersection with the scapular plane. We defined the force vector of the rotator force couple and calculated the magnitude of the shear force vector on a virtual glenoid component in both planes during glenohumeral abduction.

RESULTS

The inclination of the component positioned in the MCP averaged 95° (range, 84°-108°) and for the ICP averaged 111° (range, 94°-126°). A significant reduction in shear forces was calculated for the glenoid component in the ICP vs the MCP: 98% reduction in 60° of abduction to 49% reduction in 90° of abduction.

CONCLUSION

Shear forces are significantly higher when the glenoid component is positioned in the MCP compared with the ICP, and this is more pronounced in early abduction. Positioning the glenoid component in the inferior circle might reduce the risk of a rocking horse phenomenon.

Glenohumeral mismatch affects micromotion of cemented glenoid components in total shoulder arthroplasty

BACKGROUND

The "rocking horse" phenomenon is considered the main cause of glenoid component loosening by eccentric loading of the glenoid rim. This study aimed to investigate the influence of increasing glenohumeral implant mismatch on bone-implant interface micromotion in a cemented all-polyethylene pegged glenoid biomechanical model.

METHODS

Five glenoid sizes, 40 mm, 44 mm, 48 mm, 52 mm, and 56 mm, representing +2 mm, +6 mm, +10 mm, +14 mm, and +18 mm glenohumeral mismatch, respectively, were cyclically loaded according to ASTM Standard F2028-08 at a constant frequency of 2 Hz to a size-dependent humeral head subluxation translation. Additional glenoid components were cyclically loaded to their subluxation translations at a constant humeral head rate of 4.4 mm/s. Component micromotion was characterized as compression, distraction, and superior-inferior translation measured by differential variable reluctance transducers.

RESULTS

During constant frequency tests, 52-mm and 56-mm glenoids were unable to complete cyclic testing because of catastrophic failure of the glenoid-implant interface and permanent glenoid deformation, probably due to increasing severity of testing parameters. When tested at a constant humeral head speed, 48-mm, 52-mm, and 56-mm glenoids had significantly increased glenoid distraction and glenoid translation at cycle 50,000 compared with cycle 1. Distraction and translation measurements for 52-mm and 56-mm glenoids were significantly greater compared with 40-mm, 44-mm, and 48-mm glenoids at 50,000 cycles.

CONCLUSIONS

In a biomechanical model, optimal glenohumeral mismatch in cemented pegged glenoid implants is multifactorial and has not been definitively established. However, our data suggest that a radial mismatch of less than +10 mm may decrease the risk of glenoid micromotion.

Arthroscopic Removal of a Polyethylene Glenoid Component in Total Shoulder Arthroplasty

We present a technique for arthroscopic glenoid removal in a case of glenoid loosening after total shoulder arthroplasty (TSA). The presented technique is technically feasible and may be useful if 1-stage surgery with glenoid reimplantation is not indicated. To exclude low-grade infection, the presented technique allows for an intraoperative infection workup such as intraoperative cultures. However, glenoid loosening in TSA is a well-known problem and has been described before. The advantages of the presented technique include minimally invasive surgery, decreased pain, preservation of the subscapularis tendon, and assurance of exclusion of low-grade infection before reimplantation of a new glenoid implant. In this case a 73-year-old patient was treated with a TSA for severe osteoarthritis of the right shoulder in April 2014. Because of persistent anterior shoulder pain postoperatively, radiographic evaluation was performed and showed signs of glenoid loosening 6 months after surgery without any clinical signs of infection. To exclude low-grade infection, arthroscopy of the right shoulder was performed. Arthroscopy showed a totally loosened glenoid component leading to arthroscopic glenoid removal by use of a special forceps.

Preoperative and intraoperative infection workup in apparently aseptic revision shoulder arthroplasty

The possibility of infection should be considered in every revision shoulder arthroplasty even in the absence of clinical symptoms and signs of infection because indolent infection is prevalent. Detection of infection in apparently aseptic failed arthroplasties poses a diagnostic challenge as the conventional principles and criteria used for hip and knee arthroplasty are not generally applicable. Propionibacterium acnes and Staphylococcus epidermidis are among the infectious organisms most commonly identified in such situations. Serum inflammatory markers are essential but are often unreliable as they have poor sensitivity in the shoulder. Preoperative shoulder joint aspiration culture is an important step but is subject to high false-negative rates. Lower cutoff values of synovial fluid analysis are used for detection of periprosthetic infection than for native joint infection as demonstrated in the knee literature. Intraoperatively, frozen section should be considered when a diagnosis of infection has not been established even in the presence of clinical suspicion. Gram stain is currently not recommended because of its low sensitivity and negative predictive value. Intraoperative culture is critical and should be performed whenever there is clinical suspicion of infection. Unexpected positive intraoperative cultures are not uncommon, and 6% to 25% of them appear to represent true infection as demonstrated with positive follow-up cultures or subsequent development of infection. In revision shoulder arthroplasty, determining the presence of infection can be difficult. A standardized approach is needed to determine the best course of treatment in this particular clinical setting.

Benefit of intraoperative navigation on glenoid component positioning during total shoulder arthroplasty

INTRODUCTION

The objective of this study was to review and synthesize the current best evidence for the use of intraoperative navigation in the implantation of glenoid components in total shoulder prostheses.

METHODS

We conducted a systematic, online search using PubMed, EMBASE, CCTR, and CINAHL using "Arthroplasty, Replacement"(Mesh) AND (shoulder) AND (navi* OR computer). Data on study design and quality as well as accuracy of positioning and complications were extracted independently and in duplicate. After assessment of study heterogeneity, DerSimonian-Laird random effect models were used to pool data from the individual studies.

RESULTS

The systematic search revealed 359 manuscripts in total. After exclusion of duplicates and irrelevant publications, 6 groups of 247 shoulders from 5 studies were included. The pooled weighted mean difference for deviation from neutral version was -6.4° (95 %CI -7.9 to -5.3) in favor of navigation, which is consistent with a statistically significant difference (p < 0.01). In the navigation group, 2 superior glenoid screws were reported as perforating compared to 5 screws (1 inferior, 4 superior) in the control group. There was no difference in tilt at a WMD of 2.7 (95 %CI -1.4 to 6.8, p = 0.192).

CONCLUSIONS

Navigation allows for significantly more accurate glenoid version, but the clinical meaningfulness of the absolute improvement over standard techniques is questionable. However, navigation is a valuable teaching tool that might prove very beneficial not for the patient at hand, but for those treated by the operating surgeon in the future.

LEVEL OF EVIDENCE

Level II-meta-analysis of non-homogenous controlled trials.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.