Glenosphere dissociation after reverse shoulder arthroplasty

Evaluating trunnionosis in modular anatomic shoulder arthroplasties: a retrieval study

BACKGROUND

Shoulder arthroplasty procedures are widely indicated, and the number of shoulder arthroplasty procedures has drastically increased over the years. Rapid expansion of the utilization of reverse total shoulder arthroplasty has outpaced the more modest growth of anatomic total shoulder arthroplasty (aTSA) while shoulder hemiarthroplasty (HA) has trended down. Recently, shoulder prostheses have transitioned to increasingly modular systems offering more individualized options with the potential for decreased pain and increased range of motion. However, increased primary procedures has resulted in increased revision surgeries, with one potential cause being fretting and corrosion damage within these modular systems.

METHODS

Following institutional review board approval, 130 retrieved aTSA and 135 HA explants were identified through database query. Humeral stem and head components were included in all 265 explants, whereas 108 included polyethylene glenoid liner components. All explanted components were macroscopically evaluated for standard damage modes, and taper junctions were microscopically examined for fretting/corrosion using a modified Goldberg-Cusick classification system that was 4-quadrant graded for both the male and female component. Medical records were reviewed for patient demographics and surgical information.

RESULTS

In this series, 158 of explants were from female patients (male = 107), and 162 explants were from the right shoulder. Average age at implantation was 61 years (range: 24-83), average age at explanation was 66 years (range, 32-90), and average duration of implantation was 61.4 months (range, 0.5-240). Scratching, edge deformation, and burnishing were the most commonly observed standard damage modes. Of the 265 explants, 146 had a male stem component vs. 118 with a female stem component. Average summed fretting grades on male and female stem components were 8.3 and 5.9, respectively (P < .001). Average summed corrosion grades for male and female stem components were 8.2 and 6.2, respectively (P < .001). Wider male tapers (>11 mm) showed significantly less fretting and corrosion (P < .001). Lastly, mismatched metal compositions between the head and stem components showed greater fretting and corrosion damage (P = .002).

CONCLUSION

In this series of 265 aTSA and HA explants, there was substantial damage present on the explanted components. All components demonstrated macroscopic damage. In this retrieval study, small-tapered male stems with small, thin female heads and mismatched metal composition between components were risk factors for increased implant wear. As shoulder arthroplasty volume increases, optimizing design is paramount for long-term success. Additional work could determine the clinical significance of these findings.

Allergic reaction and metal hypersensitivity after shoulder joint replacement

PURPOSE

Metal ion release may cause local and systemic effects and induce hypersensitivity reactions. The aim of our study is first to determine if implant-related hypersensitivity correlates to patient symptoms or not; second, to assess the rate of hypersensitivity and allergies in shoulder arthroplasty.

METHODS

Forty patients with shoulder replacements performed between 2015 and 2017 were studied with minimum 2-year follow-up; no patient had prior metal implants. Each patient underwent radiographic and clinical evaluation using the Constant-Murley Score (CMS), 22 metal and cement haptens patch testing, serum and urine tests to evaluate 12 metals concentration, and a personal occupational medicine interview.

RESULTS

At follow-up (average 45 ± 10.7 months), the mean CMS was 76 ± 15.9; no clinical complications or radiographic signs of loosening were detected; two nickel sulfate (5%), 1 benzoyl peroxide (2.5%) and 1 potassium dichromate (2.5%) positive findings were found, but all these patients were asymptomatic. There was an increase in serum aluminum, urinary aluminum and urinary chromium levels of 1.74, 3.40 and 1.83 times the baseline, respectively. No significant difference in metal ion concentrations were found when patients were stratified according to gender, date of surgery, type of surgery, and type of implant.

CONCLUSIONS

Shoulder arthroplasty is a source of metal ion release and might act as a sensitizing exposure. However, patch test positivity does not seem to correlate to hypersensitivity cutaneous manifestations or poor clinical results. Laboratory data showed small constant ion release over time, regardless of gender, type of shoulder replacement and implant used.

LEVELS OF EVIDENCE

Level II.

Larger-diameter trunnions and bolt-reinforced taper junctions are associated with less tribocorrosion in reverse total shoulder arthroplasty

BACKGROUND

Morse taper junction tribocorrosion is recognized as an important failure mode in total hip arthroplasty. Although taper junctions are used in almost all shoulder arthroplasty systems currently available in the United States, with large variation in design, limited literature has described comparable analyses of taper damage in these implants. In this study, taper junction damage in retrieved reverse total shoulder arthroplasty (RTSA) implants was assessed and analyzed.

METHODS

Fifty-seven retrieved RTSAs with paired baseplate and glenosphere components with Morse taper junctions were identified via database query; 19 of these also included paired humeral stems and trays or spacers with taper junctions. Components were graded for standard damage modes and for fretting and corrosion with a modified Goldberg-Cusick classification system. Medical records and preoperative radiographs were reviewed. Comparative analyses were performed assessing the impact of various implant, radiographic, and patient factors on taper damage.

RESULTS

Standard damage modes were commonly found at the evaluated trunnion junctions, with scratching and edge deformation damage on 76% and 46% of all components, respectively. Fretting and corrosion damage was also common, observed on 86% and 72% of baseplates, respectively, and 23% and 40% of glenospheres, respectively. Baseplates showed greater moderate to severe (grade ≥ 3) fretting (43%) and corrosion (27%) damage than matched glenospheres (fretting, 9%; corrosion, 13%). Humeral stems showed moderate to severe fretting and corrosion on 28% and 30% of implants, respectively; matched humeral trays or spacers showed both less fretting (14%) and less corrosion (17%). On subgroup analysis, large-tapered implants had significantly lower summed fretting and corrosion grades than small-tapered implants (P < .001 for both) on glenospheres; paired baseplate corrosion grades were also significantly lower (P = .031) on large-tapered implants. Factorial analysis showed that bolt reinforcement of the taper junction was also associated with less fretting and corrosion damage on both baseplates and glenospheres. Summed fretting and corrosion grades on glenospheres with trunnions (male) were significantly greater than on glenospheres with bores (female) (P < .001 for both).

CONCLUSIONS

Damage to the taper junction is commonly found in retrieved RTSAs and can occur after only months of being implanted. In this study, tribocorrosion predominantly occurred on the taper surface of the baseplate (vs. glenosphere) and on the humeral stem (vs. tray or spacer), which may relate to the flexural rigidity difference between the titanium and cobalt-chrome components. Bolt reinforcement and the use of large-diameter trunnions led to less tribocorrosion of the taper junction. The findings of this study provide evidence for the improved design of RTSA prostheses to decrease tribocorrosion.

Do total shoulder arthroplasty implants corrode?

BACKGROUND

Total shoulder arthroplasty (TSA) has become the gold-standard treatment to relieve joint pain and disability in patients with glenohumeral osteoarthritis who do not respond to conservative treatment. An adverse reaction to metal debris released due to fretting corrosion has been a major concern in total hip arthroplasty. To date, it is unclear how frequently implant corrosion occurs in TSA and whether it is a cause of implant failure. This study aimed to characterize and quantify corrosion and fretting damage in a single anatomic TSA design and to compare the outcomes to the established outcomes of total hip arthroplasty.

METHODS

We analyzed 21 surgically retrieved anatomic TSAs of the same design (Tornier Aequalis Pressfit). The retrieved components were microscopically examined for taper corrosion, and taper damage was scored. Head and stem taper damage was quantitatively measured with a non-contact optical coordinate-measuring machine. In selected cases, damage was further characterized at high magnifications using scanning electron microscopy. Energy-dispersive x-ray spectroscopy and metallographic evaluations were performed to determine underlying alloy microstructure and composition. Comparisons between groups with different damage features were performed with independent-samples t tests; Mann-Whitney tests and multivariate linear regression were conducted to correlate damage with patient factors. The level of statistical significance was set at P < .05.

RESULTS

The average material loss for head and stem tapers was 0.007 mm3 and 0.001 mm3, respectively. Material loss was not correlated with sex, age, previous implant, or time in situ (P > .05). We observed greater volume loss in head tapers compared with stem tapers (P = .002). Implants with evidence of column damage had larger volumetric material loss than those without such evidence (P = .003). Column damage aligned with segregation bands within the alloy (preferential corrosion sites). The average angular mismatch was 0.03° (standard deviation, 0.0668°), with negative values indicating distal engagement and positive values indicating proximal engagement. Implants with proximal engagement were significantly more likely to have column damage than those with distal engagement (P = .030).

DISCUSSION

This study has shown not only that the metal components of TSA implants can corrode but also that the risk of corrosion can be reduced by (1) eliminating preferential corrosion sites and (2) ensuring distal engagement to prevent fluid infiltration into the modular junction.

Tribocorrosion is Common, but Mild in Modular Humeral Components in Shoulder Arthroplasty: An Implant Retrieval Analysis

Background

Wear and corrosion at the junctions of modular implants are increasingly recognized issues in the design of hip and knee arthroplasty prostheses, yet less is known about their significance in shoulder arthroplasty.

Methods

A query of paired total shoulder implant specimens (eg, humeral head and stem components from the same patient) was performed using an institutional implant retrieval registry. Implants were examined under a stereomicroscope and evaluated for evidence of fretting and corrosion using the modified Goldberg scoring system. Available electronic medical records of included specimens were reviewed to report relevant clinical characteristics and identify potential associations with the presence of tribocorrosion.

Results

Eighty-three paired total shoulder implant specimens, explanted at a single institution between 2013 and 2020, were analyzed. Corrosion was identified in 52% (43/83) of humeral head components and 40% (33/83) of humeral stem components. Fretting was identified in 29% (24/83) of humeral head components and 28% (23/83) of humeral stem components. Of the 56 paired implants for which clinical data were available, the duration of implantation (DOI) was less than 2 years in 29% of paired implants and greater than 5 years in 36% of implants. The presence of corrosion or fretting was not associated with DOI, a male humeral head taper, or periprosthetic infection as the indication for revision.

Conclusion

Mild tribocorrosion was present in more than half of the retrieved humeral implant specimens. However, trunnionosis did not manifest as a clinical cause of revision surgery in our study.

Mechanical complications and fractures after reverse shoulder arthroplasty related to different design types and their rates: part I

The initial reverse shoulder arthroplasty (RSA), designed by Paul Grammont, was intended to treat rotator cuff tear arthropathy in elderly patients. In the early experience, high complication rates (up to 24%) and revision rates (up to 50%) were reported.The most common complications reported were scapular notching, whereas clinically more relevant complications such as instability and acromial fractures were less commonly described.Zumstein et al defined a 'complication' following RSA as any intraoperative or postoperative event that was likely to have a negative influence on the patient's final outcome.High rates of complications related to the Grammont RSA design led to development of non-Grammont designs, with 135 or 145 degrees of humeral inclination, multiple options for glenosphere size and eccentricity, improved baseplate fixation which facilitated glenoid-sided lateralization, and the option of humeral-sided lateralization.Improved implant characteristics combined with surgeon experience led to a dramatic fall in the majority of complications. However, we still lack a suitable solution for several complications, such as acromial stress fracture. Cite this article: EFORT Open Rev 2021;6:1097-1108. DOI: 10.1302/2058-5241.6.210039.

Case Report: Watching and Waiting? A Case of Incomplete Glenosphere Seating With Spontaneous Reversal in Reverse Shoulder Arthroplasty

Introduction: Reverse shoulder arthroplasty is a useful procedure with broadening applications, but it has the best outcomes when used for rotator cuff tear arthropathy. However, this procedure is not without complications. While scapular notching and aseptic loosening are more common complications that have been extensively studied in the literature, dissociation of the glenoid component and incomplete glenosphere seating has not received much attention. Specifically, little research has explored appropriate management of incomplete seating of the glenosphere component, and no gold standard for treatment of this complication has emerged.

Methods: In the case described here, an elderly patient with an incompletely seated glenosphere component post-operatively opted to pursue conservative management in order to avoid revision surgery if possible.

Results: The partially engaged, superiorly directed components in this case exhibited spontaneous complete and symmetric seating of the glenosphere between six and twelve months post-operatively, indicating that conservative management of this complication in low-demand patients may be a viable option to avoid the risks associated with revision surgery.

Conclusion: Further research should be pursued to explore what patient and prosthesis design factors may be suited to observation with serial radiographs when incomplete seating of the glenosphere component occurs.

Causes of acromion and scapular spine fractures following reverse shoulder arthroplasty: a retrospective analysis and literature review

Purpose

Fractures of the acromion and the scapular spine are serious complications after reverse total shoulder arthroplasty. They concern about 4 to 5% of the patients and always result in a significant deterioration of shoulder function. Different causes have been taken into consideration, particularly stress or fatigue fractures. The purpose of the present study was to analyse our own cases and to discuss the causes reported in the literature.

Methods

We reviewed our shoulder arthroplasty registry and the consultation reports of the last ten years. The charts and radiographs of all patients who had a post-operative fracture of the acromion or the scapular spine were carefully examined and the results were compared with those of an age- and gender-matched control group.

Results

Twelve patients with an average age of 79 years sustained a fracture of the acromion (n = 6) or the scapular spine (n = 6). The time interval between the operation and the fracture averaged 26 months and ranged from three weeks to 70 months. Eight patients (67%) had a trauma. Seven of them reported a fall on the corresponding shoulder and one a heavy blow on the acromion. The four non-traumatic fractures were attributed to poor bone quality. All 12 patients had immediate pain and difficulty to actively elevate the affected arm. The time interval between the fracture and its diagnosis averaged ten weeks (0 to 10 months). At final follow-up, all patients could reach their face and refused further surgery. Two patients rated their result as good, six as acceptable and four as poor.

Conclusions

Our study cannot support the hypothesis that most acromion and scapular spine fractures after RSA are the result of increased tension in the deltoid or stress fractures. In our series, the majority of the fractures were related to a fall. Implantation of a reverse prosthesis exposes the acromion and makes it more vulnerable to direct trauma. Non-traumatic fractures were associated with poor bone quality.

Clinical effectiveness and safety of the extended humeral head arthroplasty for selected patients with rotator cuff tear arthropathy

BACKGROUND

Cuff tear arthropathy is commonly managed with a reverse total shoulder arthroplasty (RTSA). A humeral hemiarthroplasty with an extended humeral head may provide a less invasive alternative for selected patients with cuff tear arthropathy if the shoulder has preserved active elevation. Because evidence regarding this procedure is limited, we investigated its safety and efficacy in treating selected patients with cuff tear arthropathy.

METHODS

We analyzed the preoperative characteristics, surgical findings, and clinical outcomes for patients selected for extended head hemiarthroplasty.

RESULTS

For 42 patients with 2-year follow-up, there were no complications or revisions. The Simple Shoulder Test score improved from a median of 3.0 to 8.0 (P < .001). The median percentage of maximal possible improvement was 50% (P < .001). The percentage of patients able to perform each of the functions of the Simple Shoulder Test was significantly improved; for example, the ability to sleep comfortably increased from 19% to 71%, and the ability to place a coin on the shelf at shoulder level increased from 38% to 86% (P < .001).

CONCLUSIONS

There are circumstances in which RTSA is clearly the preferred procedure for cuff tear arthropathy, including pseudoparalysis, anterosuperior escape, and glenohumeral instability; however, in shoulders with preserved active motion and stability of the humeral head provided by an intact coracoacromial arch, the extended head humeral arthroplasty can enable selected patients to realize improved comfort and function without the potential risks of RTSA. Extended humeral head hemiarthroplasty can provide a safe and effective alternative for the management of selected patients with rotator cuff tear arthropathy and preserved active motion.

In vivo blood metal ion levels in patients after total shoulder arthroplasty

BACKGROUND

Products from metal wear have been identified as a potential cause of adverse local tissue reactions and implant failure in total hip arthroplasty. However, the role of metal ion exposure in patients after total shoulder replacement is unclear. The objective of the present study was to determine in vivo blood metal ion levels of cobalt, chromium, and titanium in patients after anatomic total shoulder arthroplasty (TSA) or reverse TSA.

METHODS

A consecutive series of patients after anatomic TSA or reverse TSA was evaluated retrospectively. After exclusion of patients with additional metal implants, 40 patients with unilateral anatomic TSA (n = 20) or reverse TSA (n = 20) were available for whole-blood metal ion analysis at a mean follow-up of 28 ± 9.6 months. Twenty-three healthy individuals without metal implants served as a control group.

RESULTS

Mean cobalt ion concentrations were 0.18 µg/L (range, 0.1-0.66 µg/L), 0.15 µg/L (range, 0.03-0.48 µg/L), and 0.11 µg/L (range, 0.03-0.19 µg/L), mean chromium ion levels were 0.48 µg/L (range, 0.17-2.41 µg/L), 0.31 µg/L (range, 0.09-1.26 µg/L), and 0.14 µg/L (range, 0.04-0.99 µg/L), and mean titanium ion concentrations were 1.31 µg/L (range, 0.75-4.52 µg/L), 0.84 µg/L (range, 0.1-1.64 µg/L), and 0.62 µg/L (range, 0.32-2.14 µg/L) in the reverse TSA group, the anatomic TSA group, and the control group, respectively.

CONCLUSIONS

TSA resulted in elevated metal ion levels compared with healthy controls, although overall metal ion concentrations measured in this study were relatively low. The role of local metal ion exposure in patients with total shoulder replacements should be further investigated.

Complications in reverse shoulder arthroplasty

The reported rate of complications of reverse shoulder arthroplasty (RSA) seems to be higher than the complication rate of anatomical total shoulder arthroplasty.The reported overall complication rate of primary RSA is approximately 15%; when RSA is used in the revision setting, the complication rate may approach 40%.The most common complications of RSA include instability, infection, notching, loosening, nerve injury, acromial and scapular spine fractures, intra-operative fractures and component disengagement.Careful attention to implant design and surgical technique, including implantation of components in the correct version and height, selection of the best glenosphere-humeral bearing match, avoidance of impingement, and adequate management of the soft tissues will hopefully translate in a decreasing number of complications in the future. Cite this article: Barco R, Savvidou OD, Sperling JW, Sanchez-Sotelo J, Cofield RH. Complications in reverse shoulder arthroplasty. EFORT Open Rev 2016;1:72-80. DOI: 10.1302/2058-5241.1.160003.

Fretting and Corrosion in Modular Shoulder Arthroplasty: A Retrieval Analysis

Tribocorrosion in taper junctions of retrieved anatomic shoulder arthroplasty implants was evaluated. A comparison of the tribocorrosion between cobalt-chromium and titanium alloy stems was conducted and the observations were correlated with the individual's clinical data. Adverse effects caused by metal debris and subsequent elevated serum metal ion levels are frequently reported in total hip arthroplasty. In total shoulder arthroplasty, to date only a small number of retrieval analyses are available and even fewer address the issue of tribocorrosion at the taper junctions. A total of 36 retrieved hemiarthroplasties and total shoulder arthroplasties were assessed using the modified Goldberg score. The prevalence of fretting and corrosion was confirmed in this cohort. Titanium stems seem to be more susceptible to damage caused by tribocorrosion than cobalt-chromium stems. Furthermore, stemless designs offered less tribocorrosion at the taper junction than stemmed designs. A weak correlation between time to revision and increased levels of tribocorrosion was seen. Whether or not tribocorrosion can lead to adverse clinical reactions and causes failure of shoulder arthroplasties remains to be examined.

A nondestructive method to verify the glenosphere-baseplate assembly in reverse shoulder arthroplasty

BACKGROUND

Glenoid dissociation is a rare postoperative complication in reverse shoulder arthroplasty that has severe consequences for the patient and requires revision in most cases. A mechanically compromised Morse taper is hypothesized to be the main cause of this complication, with bony impingements and soft tissue interpositioning being cited as the most important problems. Intraoperative assessment of the taper assembly is challenging. Current methods require applying considerable torque to the glenosphere or relying on radiographs.

MATERIALS AND METHODS

This in vitro study demonstrates how the assembly quality can be accurately determined in a nondestructive way by exploiting the implant-specific relation between screw and Morse taper characteristics by measuring the angular rotation-torque curve.

RESULTS

The feasibility of the method is demonstrated on 2 reverse implant models. Several data features that can statistically discriminate between optimal and suboptimal assemblies are proposed.

CONCLUSION

Suboptimal assemblies can be detected using the method presented, which could easily be integrated in the current surgical workflow. Clinical recommendations based on the method's rationale are also presented, allowing detection of the most severe defect cases with surgical instruments currently in use.

Revision for a failed reverse: a 12-year review of a lateralized implant

BACKGROUND

The purpose of this study was (1) to evaluate the rates of reverse shoulder arthroplasty (RSA) revisions during a 12-year period, (2) to assess the influence of primary diagnosis and the impact of implant modifications on revisions, (3) to describe surgical management of failed RSA, and (4) to analyze outcomes of patients with minimum 24-month follow-up.

METHODS

A retrospective database review identified primary diagnosis for 1418 patients who underwent RSA from 2000 to 2012. A subgroup of 85 patients required return to the operating room for removal or exchange of components. Indication to reoperate, intraoperative management, and outcomes were reviewed. Indications were grouped into 7 categories: baseplate failure, humeral component dissociation, glenosphere dissociation, glenohumeral dislocation, aseptic humeral loosening, periprosthetic fracture, and infection. During the study, design modifications were made to the baseplate, humeral socket, and glenosphere. Surgical strategies were analyzed through operative reports. Range of motion, American Shoulder and Elbow Surgeons scores, and Simple Shoulder Test scores were collected before and after surgery and compared for 58 patients with 2-year follow-up.

RESULTS

Overall revision rate was 6%. Patients undergoing RSA for failed hemiarthroplasty had the highest revision rate (10%). Indications for revision included baseplate failure (2.5%), infection (1.3%), humeral dissociation (0.7%), glenosphere dissociation (0.6%), periprosthetic fracture (0.4%), glenohumeral dislocation (0.4%), and aseptic humeral loosening (0.3%). Baseplate modifications reduced the incidence of baseplate failure to 0.3%. Range of motion and the Simple Shoulder Test and American Shoulder and Elbow Surgeons scores improved.

CONCLUSION

Although revision RSA is challenging, with higher risk for complications compared with primary RSA, patients still exhibit significant clinical improvements.

Tribocorrosion in shoulder arthroplasty humeral component retrievals

BACKGROUND

Tribocorrosion at the modular taper connections of total hip implants has been associated with trunnionosis and adverse local tissue reactions. Modularity is also widely used in shoulder arthroplasty implants, but little information exists about the potential for tribocorrosion. This study hypothesized that there would be mild or no tribocorrosion in a series of retrieved shoulder implants.

METHODS

A total of 28 implants with a mean implantation time of 6.2 ± 6.0 years were evaluated using a validated damage scoring method. Implant tapers on the head and stem were divided into upper (deepest) and lower zones and independently scored for fretting and corrosion damage from 1 (none) to 4 (severe).

RESULTS

Corrosion was present on 32% of heads and 38% of stems, whereas fretting was present on 36% of heads and 46% of stems. There was significantly greater (P = .02) corrosion in the lower zone of the retrieved stems (1.4 ± 0.5) than there was in the upper zone (1.1 ± 0.3). Correlation between the head and stem corrosion for lower zone was moderate (r = 0.41; P = .04).

DISCUSSION

Tribocorrosion was present on the heads and stems of some of the retrieved shoulder implants examined in this study. The incidence of tribocorrosion in shoulder implants was lower than in reported cases of retrieved hip implants. The greatest damage was in the lower zone of the taper, where the connection may be exposed to the surrounding joint fluid. It remains to be seen whether this leads to any clinical presentation of trunnionosis.