Adjusting Implant Size and Position Can Improve Internal Rotation After Reverse Total Shoulder Arthroplasty in a Three-dimensional Computational Model

BackgroundEfforts during reverse total shoulder arthroplasty (RSA) have typically focused on maximizing ROM in elevation and external rotation and avoiding scapular notching. Improving internal rotation (IR) is often overlooked, despite its importance for functional outcomes in terms of patient self-care and hygiene. Although determinants of IR are multifactorial, it is unable to surpass limits of bony impingement of the implant. Identifying implant configurations that can reduce bony impingement in a computer model will help surgeons during preoperative planning and also direct implant design and clinical research going forward.Questions/purposesIn a CT-modeling study, we asked: What reverse total shoulder arthroplasty implant position improves the range of impingement free internal rotation without compromising other motions (external rotation and extension)?MethodsCT images stored in a deidentified teaching database from 25 consecutive patients with Walch A1 glenoids underwent three-dimensional templating for RSA. Each template used the same implant and configuration, which consisted of an onlay humeral design and a 36-mm standard glenosphere. The resulting constructs were virtually taken through ROM until bony impingement was found. Variations were made in the RSA parameters of baseplate lateralization, glenosphere size, glenosphere overhang, humeral version, and humeral neck-shaft angle. Simulated ROM was repeated after each parameter was changed individually and then again after combining multiple changes into a single configuration. The impingement-free IR was calculated and compared between groups. We also evaluated the effect on other ROM including external rotation and extension to ensure that configurations with improvements in IR were not associated with losses in other areas.ResultsCombining lateralization, inferiorization, varus neck-shaft angle, increased glenosphere size, and increased humeral anteversion resulted in a greater improvement in internal rotation than any single parameter change did (median baseline IR: 85° [interquartile range 73° to 90°]; combined changes: 119° [IQR 113° to 121°], median difference: 37° [IQR 32° to 43°]; p < 0.001).ConclusionIncreased glenosphere overhang, varus neck-shaft angle, and humeral anteversion improved internal rotation in a computational model, while glenoid lateralization alone did not. Combining these techniques led to the greatest improvement in IR.Clinical RelevanceThis computer model study showed that various implant changes including inferiorization, varus neck-shaft angle, increased glenosphere size, and increased humeral anteversion can be combined to increase impingement-free IR. Surgeons can employ these currently available implant configurations to improve IR when planning and performing RSA. These findings support the need for further clinical studies validating the effect of implant configuration on resultant IR.     

Effect of reverse total shoulder arthroplasty humeral inclination on glenohumeral range of motion,deltoid force,and glenoid strain: a biomechanical study

BackgroundReverse total shoulder arthroplasty (RSA) primarily varies between 2 implant design options: a 135 humeral stem inclination that closely resembles anatomic orientation, versus the Grammont-style 155 humeral stem inclination that further medializes and distalizes the center of rotation (COR). The purpose of this study was to compare deltoid force, glenoid strain, and simulated glenohumeral range of motion (ROM) between RSA 135 and RSA 155 designs, with a series of standardized permutations of glenosphere offset and rotator cuff pathology.MethodsTwelve fresh-frozen cadaveric shoulder specimens were studied using a shoulder simulator. Native shoulder motion profiles for reproducible abduction range of motion were established using a customized testing device. Optical 3-dimensional tracking and pressure sensors were used to accurately record glenohumeral range of motion (ROM), deltoid force, and glenoid strain for RSA 135 and RSA 155 designs. For each cohort, all combinations of glenosphere offsets and rotator cuff tendon involvement were evaluated.ResultsThere was no significant difference in the overall abduction ROM between the 155 and the 135 humeral stem implants (P = .75). Resting abduction angle and maximum abduction angle were significantly greater with a 155 + STD (standard offset) construct than with a 135 + STD construct (P < .001 and P = .01, respectively). Both stem inclinations decreased combined deltoid force requirements as compared the native shoulder with a massive cuff tear. Effective glenoid strain did not vary significantly between 135 + STD and 155 + STD constructs (P = .66).ConclusionOverall, range of motion between the 135 and the 155 humeral stem inclinations was not significantly different. The cumulative deltoid force was lower in RSA shoulders when compared to native shoulders with massive rotator cuff tears, highlighting the utility of both implant designs. The Grammont-style 155 stem coupled with a 2.5 mm inferior offset glenosphere required less deltoid force to reach maximum abduction than did the more anatomic, lateralized 135 stem coupled with a 4 mm lateral offset glenosphere.Level of EvidenceBasic Science, Biomechanics Controlled Laboratory Study     

Clinical and radiographic results of eccentric glenoid reaming in reverse total shoulder arthroplasty

BackgroundOne option for treating glenoid bone loss in reverse shoulder arthroplasty (RSA) is eccentric reaming of the glenoid, but the effect on clinical results is unclear. The aim of this study was to investigate the association between medialization of the bone-baseplate interface (herein, ‘medialization’) caused by eccentric reaming of the glenoid and scapular notching, baseplate loosening, and clinical outcomes after RSA.MethodsWe retrospectively reviewed data for 91 patients who underwent primary RSA between January 2014 and December 2016 with a lateralized implant and a minimum 2-year follow-up. The amount of medialization was estimated using a 3-dimensional computed tomography scan-based computer planning software. The average amount of medialization estimated by the 3-dimensional planning software was 3.4 mm (range, 0.5-10 mm). Outcomes included range of motion (ROM), American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST) score, visual analog scale (VAS) for pain, and the rates of scapular notching and baseplate loosening. The association between the estimated medialization and the outcomes of interest was evaluated using multivariate models.ResultsAfter controlling for age, sex, diagnosis, subscapularis repair, glenosphere size, and baseline ROM, medialization was not associated with the postoperative abduction (P = .35), external rotation (ER) at 90° (P = .16), internal rotation at 90° (P = .08), and internal rotation at the back (P = .06). However, we found a significant association between medialization and postoperative ER at the side (P = .02). According to the multivariate model, for a 1-mm increase in medialization during surgery, a decrease of 1.6° in postoperative ER would be expected. We found no association between medialization and the postoperative ASES score (P = .48), SST score (P = .59), or VAS score (P = .27). At a minimum of 2 years of follow-up, we found no baseplate loosening or radiographic signs of baseplate loosening in any patient. Scapular notching of grades 1 to 2 was observed in 22 patients (24%). We were not able to detect a difference in scapular notching when medialization was > 1 mm ver when medialization ≤ 1 mm (odds ratio, 2.5; 95% confidence interval: 0.28-23).ConclusionsIncreasing medialization due to eccentric reaming after RSA with a lateralized implant was associated with a decrease in postoperative ER at the side. However, increasing medialization was not associated with worse patient-reported outcome scores or increased baseplate loosening at short-term follow-up.     

Neutral glenoid alignment in reverse shoulder arthroplasty does not guarantee decreased risk of impingement

Reverse Shoulder Arthroplasty (RSA) has gained popularity over the recent years, but impingement concerns are still present. Surgeons aim to correct pre‐operative glenoid deformities to reduce impingement but it can be challenging without assistance like patient specific guides. However, it is unclear how accurate glenoid correction affects the impingement. The main objective of this study was to determine whether accurate glenoid correction to neutral version and tilt can reduce the risk of impingement. Two types of virtual surgeries were performed on 22 pre‐operative arthritic shoulders: (i) “Interactive,” the glenoid baseplate could be placed with accuracy, and (ii) “Blind,” surgeons placed the RSA baseplate while they could only visualize the glenoid. The virtual models were then used in an RSA biomechanical model which recorded impingement for (i) four Range of Motion (ROM) tasks, (ii) ten Activities of Daily Living (ADL). The “Blind” method resulted in more variable glenoid placement (version and tilt) than the “Interactive” method (p = 0.001). However, both methods showed similar ROM and impingement occurrence in ADLs. The results suggest it is challenging for surgeons to accurately correct version and tilt on arthritic glenoids when only referencing off of the face of the glenoid. However, the variable glenosphere placement observed in the “Blind” method did not result in worse impingement compared to the accurate “Interactive” method. This was because both methods had similar inferior baseplate positioning which is more important than correcting version or tilt. Implantation accuracy remains important in RSA, but pre‐operative planning should not just target at correcting version and tilt. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1213–1219, 2018.

     

Does critical shoulder angle predict abduction motion and acromion-tuberosity impingement in reverse shoulder arthroplasty?

BackgroundVirtual planning software for reverse shoulder arthroplasty (RSA) has introduced the ability to optimize implant position in an effort to maximize bony impingement–free motion. Abduction impingement typically occurs between the glenoid and polyethylene or between the tuberosities and the acromion or coracoid. Acromion-tuberosity impingement has been considered less desirable, as it may create additional stress on the acromion. Patients with a large acromion overhang may have higher rates of acromion-tuberosity impingement. As the critical shoulder angle (CSA) represents a larger distance from the glenoid face to the acromion, the purpose of this study was to evaluate the impact of implant selection and position on abduction motion and acromion-tuberosity impingement, with a focus on the association to CSA. We hypothesize that a larger CSA will be associated with less abduction motion and an increase in acromion-tuberosity impingement.MethodsThis is a retrospective cohort case series of 85 consecutive patients who underwent RSA from June 2020 to January 2021. Humeral and glenoid components were implanted virtually (SurgiCase) using a standard protocol for a single implant system (DJO AltiVate Short Stem Reverse) with an inset humeral component. Implant variables analyzed included baseplate location (central vs. inferior glenoid), glenosphere lateralization (10 mm vs. 6 mm), and humeral shell (standard vs. semiconstrained). The maximal degree of abduction and location of impingement were recorded at external rotation of 0°, 45°, and 90°. Implant combinations that resulted in no impingement and no motion were recorded.ResultsIncrease in CSA was associated with acromion-tuberosity impingement for nearly every combination at 0° and 45° external rotation; however, there were no significant associations between CSA and maximum abduction motion. Acromion-tuberosity impingement was associated with central glenosphere placement in all degrees of external rotation (P < .001), use of a 10 mm lateralized glenosphere for 0° (P < .001) and 45° (P = .076), and using a standard polyethylene shell for 0° (P = .032) and 45° external rotation (P = .007). Maximal abduction motion was associated with inferior placement (P < .001), and use of a 10 mm lateralized glenosphere (P < .001) in all positions of external rotation but was not influenced by the polyethylene type.ConclusionIncreased CSA is associated with acromion-tuberosity impingement and can be used to screen for patients at risk for bony impingement in abduction. Placement of the glenosphere centrally and use of a 10 mm lateralized glenosphere were associated with higher rates of acromion-tuberosity impingement. Maximal abduction can be achieved using a 10 mm lateralized glenosphere and inferior placement.     

Long-term Reverse Total Shoulder Arthroplasty Outcomes: The Effect of the Inferior Shifting of Glenoid Component Fixation

BackgroudThe 155° Grammont reverse shoulder replacement has a long track record of success, but also a high radiographic notching rate. The increased distance between the scapular pillar and the humeral component theoretically decreases postoperative notching. The glenoid component can be shifted inferiorly relative to the glenoid; however, there also is some concern that shifting the glenoid component too far inferiorly (inferior glenoid component overhang > 3.5 mm) may compromise long-term stability of the glenoid component. This study was conducted to determine if clinical outcomes, scapular notching, and complications vary with more inferior placement of the glenoid component.MethodsA retrospective analysis of prospectively collected data was performed in order to compare radiographic outcomes (notching rate and signs of glenoid loosening or component disassembly) and clinical outcomes (range of motion, Constant score, subjective shoulder value, and complication rate) of all patients who underwent reverse shoulder replacement with the glenosphere positioned either flush with the inferior rim of the glenoid (flush group) or with at least 3.5 mm of inferior overhang (overhang group) at a minimum follow-up of 60 months. Ninety-seven patients ultimately met the inclusion criteria, with 41 patients with flush glenoid component and 56 patients with at least 3.5 mm of inferior overhang.ResultsAverage follow-up was 97.8 months. The overhang group had a lower rate of radiographic notching (37% vs. 82.5%, p < 0.05), better clinical outcomes (improvement in Constant score: +40 vs. +32, p = 0.036), and higher subjective shoulder value (79 vs. 69, p = 0.026) than the flush group. No difference in complications between groups was found.ConclusionsIn this study, at least 3.5 mm of inferior glenosphere overhang relative to the inferior rim of the glenoid was associated with the lower notching rate without negative effect on the clinical outcomes in 155° Grammont-style reverse shoulder replacement. Therefore, no increase in complications should be expected when using this surgical technique.     

The use of an eccentric glenosphere compared with a concentric glenosphere in reverse total shoulder arthroplasty: two-year minimum follow-up results

Purpose

The current models of reverse shoulder arthroplasty (RSA) expose the procedure to the risk of scapular notching, possibly leading to loosening of the glenoid. We compared the clinical and radiographic results obtained with a concentric or eccentric glenosphere to assess whether the eccentric design might give better clinical results and avoid or decrease the risk of scapular notching

Methods

Of our patients, 31 underwent RSA using a concentric glenosphere (group A), while 29 had an eccentric glenosphere (group B). Postoperatively, patients were followed-up at one to 12 months and annually thereafter, with the mean being 33 months in group A and 27.5 in group B. In both groups the minimum follow up (F-U) was 24 months. Preoperatively and at each F-U starting from six months, patients were assessed using the Constant score. On radiographs, prosthesis scapular neck angle (PSNA), distance between scapular neck and glenosphere (DBSNG) and peg-glenoid rim distance (PGRD) were calculated. The severity of notching was classified in four grades.

Results

In group A the mean Constant score increased by 30 points compared to the preoperative score and the active ROM increased considerably. At latest F-U, the mean PSNA, DBSNG and PGRD were, respectively, 87°, 3.4 mm and 19.8 mm. Glenoid notching was present in 42 % of cases. In group A, the mean Constant score increased by 34 points and the mean ROM was better than in group A. The average PSNA, PGRD and DBSNG were, respectively, 92°, 21.2 mm and 4.3 mm. Radiographs showed no inferior scapular notching.

Conclusions

The eccentric glenosphere yielded better clinical results than the concentric glenosphere and was associated with no scapular notching.     

Correcting retroversion during reverse shoulder arthroplasty for B2 glenoids leads to medialization and worsens impingement on the scapular neck

BackgroundReverse shoulder arthroplasty (RSA) is a viable option for posteriorly-eroded B2 glenoids. But little is known in this setting about the effect of baseplate version on impingement on the scapular neck, which affects the risk of notching, the risk of impingement-related instability, and the passive range of motion (ROM). Correcting retroversion with eccentric reaming leads to medialization to achieve full support of the baseplate, bringing the humerus closer to the scapula and potentially increasing impingement on the scapular neck. We hypothesized that correcting retroversion in B2 glenoids would result in increased medialization and worse impingement on the scapular neck.MethodsTen patients with Walch B2 glenoids underwent a simulated RSA. For each patient, a 25 mm baseplate was digitally implanted along the inferior margin of the glenoid, centered anterior-to-posterior, in 0˚ of inclination, with 100% backside contact, with a 36 mm glenosphere and 145˚ neck-shaft angle. Impingement-free ROM was then simulated with 17 different implant arrangements: baseplate version of P (the pathologic version), −15˚, -10˚, −5˚, 0˚, and baseplate lateralization +0, +3mm, +6mm. Two additional simulations consisted of half-wedge baseplates seated at the best fit (matching the paleoglenoid) and 0˚ version. The primary endpoint was external rotation at the side (ERS), based on in-vivo analyses that reveal this as the primary mode of notching and impingement-related instability. Data was analyzed using paired t-test, analysis of variance (ANOVA), and a multivariable regression analysis.ResultsIn every simulation in every patient, correcting retroversion worsened scapular neck impingement with ERS, the primary mode of notching and impingement-related instability. Overall, implantation in retroversion led to 33% more ERS (P = .02). The magnitude of this effect was much greater with medialized glenoids: 100% more ERS for +0 baseplates and 23% more ERS for +6 (P = .008). Half-wedge baseplates resulted in more ERS than +0 baseplates: 2.3x more at 0˚ version (P = .02). Any correction of version resulted in increased medialization (all P < .01), which led to worse scapular neck impingement. Multiple linear regression analysis showed that baseplate lateralization has the most impact on scapular neck impingement (β = 0.640; P < .001).ConclusionIn B2 glenoids undergoing RSA, correcting the glenoid retroversion with eccentric reaming results in significantly more medialization, worsening scapular neck impingement with ERS. This can increase the risk of notching, may lead to impingement-related instability, and decreases passive ERS.Level of evidenceClinical science study     

A randomized prospective study comparing migration of hydroxyapatite and non-hydroxyapatite coated glenoid components using radiostereometric analysis

BackgroundPrimary shoulder arthroplasty can significantly improve quality of life; however, the glenoid baseplate remains the most common component to loosen, which may result in implant failure and subsequent revision surgery. Radiostereometric analysis (RSA) is considered the gold standard for accurate measurement of micro-motion between implant and bone. The aims of this study were to compare migration of the Lima SMR porous titanium hydroxyapatite (HA) coated and non-hydroxyapatite (non-HA) coated glenoid components through a prospective, randomized 2-arm trial using RSA, whilst also comparing clinical and functional outcomes.MethodsTwenty patients were randomized into 2 equal (HA and non-HA coated) groups with all patients undergoing primary anatomic shoulder arthroplasty, at which time tantalum beads were also inserted. RSA imaging was performed immediately postoperatively, then at 3, 6, 12, and 24 months postprocedure. These images were digitized and analyzed using model-based RSA software. All patients completed Oxford Shoulder Score (OSS), American Shoulder and Elbow Surgeons (ASES) score, Constant Score (CS) and Visual Analogue Scale (VAS) pain scores pre-and postoperatively at the aforementioned time points. Unpaired t-tests were used for clinical outcome data; Mann-Whitney U tests were used for RSA data. Significance levels were set at P < .05.ResultsMean age for the HA group was 72.3 years; 69.5 years for the non-HA group. Mean follow-up for both groups was above 36 months. No significant differences in glenoid migration were observed at each of the postoperative time points; the only exception being at 12 months (non-HA group displaying significantly greater rotation in the z-axis). The HA group displayed fractionally more translation in the x- and z-axes at all time points (not significant). Rotation in the z-axis was marginally greater at all postoperative time points in the non-HA group. Median total migration values revealed greater motion for the non-HA group at 3, 6, and 12 months (not significant). All clinical outcome measures improved significantly within each group; no statistical differences were observed between the groups for any outcome measure. One patient in each group underwent revision surgery to reverse shoulder arthroplasty due to unexplained pain (HA group) and cuff failure (non-HA group) only. Radiolucent lines were noted in 2 patients who are still under follow-up.ConclusionThis study has revealed promising early results of both HA coated and non-HA coated implants, however, hydroxyapatite coating of glenoid components does not significantly improve outcome scores nor provide extra stability compared to non-hydroxyapatite coated implants at 2 years postprocedure.Level of evidenceLevel II; Randomized Controlled Trial     

Glenoid revision surgery after total shoulder arthroplasty.

Forty-eight shoulders that underwent glenoid component revision surgery were reviewed at a mean of 4.9 years (range, 2 to 12 years). The indications for surgery were glenoid component loosening in 29 shoulders, glenoid implant failure in 14 shoulders, and glenoid component malposition or wear leading to instability in 5 shoulders. Seventeen shoulders had associated instability. Thirty shoulders underwent implantation of a new glenoid component and 18 underwent removal of the component and bone grafting for bone deficiencies. There was significant pain relief, improvement in active elevation and external rotation, and satisfaction with revision glenoid surgery (P <.05). Patients without a glenoid component were significantly less satisfied with the procedure than those patients who underwent reimplantation of a glenoid component (P =.01). Satisfactory pain relief was achieved in 86% of patients with a new glenoid component and 66% of patients who underwent glenoid component removal. Seven shoulders with a new glenoid component (2 for glenoid loosening) and 5 who underwent removal without reimplantation (3 for painful glenoid arthritis) required re-revision surgery. Eleven of the 17 patients with instability were stable at the most recent follow-up. The data from this study suggest that at the time of revision glenoid surgery, patients who have placement of a glenoid component have a higher degree of satisfaction than those undergoing glenoid component removal. Patients who continue to have pain after bone grafting without placement of a component may be candidates for glenoid component placement after graft consolidation.     

Clinical and radiological outcome of the Total Evolutive Shoulder System (TESS®) reverse shoulder arthroplasty: a prospective comparative non-randomised study

Purpose

The aims of this study were to assess the function and quality of life after the Total Evolutive Shoulder System (TESS) reverse shoulder arthroplasty (RSA), to evaluate the radiological stability of the stemless version and to address the effect of arm lengthening and scapular notching (SN) on the outcome.

Methods

This was a prospective comparative non-randomised study. A total of 37 consecutive patients (40 shoulders) underwent TESS RSA between October 2007 and January 2012; 16 were stemless and 26 were stemmed. At a mean follow-up of 39 months (15–66), we evaluated range of motion (ROM), pain and functional outcome with QuickDASH and quality of life with EQ-5D score. Radiologically, component positioning, signs of loosening, SN and arm length difference were documented.

Results

We found a significant improvement in functional outcome and reduction of pain in both stemmed and stemless groups. No humeral loosening was evident, but there were four glenoid loosenings. In 12 shoulders that developed SN, seven already had scapular bone impression (SBI) evident on initial post-operative radiographs. Glenoid overhang seemed to decrease the risk of SN. Arm lengthening was associated with better EQ-5D but did not influence ROM or functional outcome.

Conclusions

Reverse shoulder arthroplasty markedly improved shoulder function. SN is of concern in RSA, but proper positioning of the glenoid component may prevent its development.     

Baseplate augmentation strategies: optimizing range of motion with reverse shoulder arthroplasty based upon variable glenoid deformity

IntroductionVarious operative strategies exist to address glenoid deformity in patients undergoing reverse shoulder arthroplasty (RSA). There is lack of guidance in pairing operative strategies with type and severity of deformity especially with regard to glenoid lateralization, humeral lateralization, and global lateralization. The purpose of this study is to compare different glenoid baseplates on their ability to provide optimal glenoid lateralization and improve range-of-motion based upon pattern and severity of deformity in glenohumeral osteoarthritis.MethodsCT scans were chosen from a large database of osteoarthritic shoulders until ten from each of the following three cohorts were identified: 1) no deformity: retroversion <10° and inclination deformity <5°, 2) Uniplanar deformity: retroversion >15° and inclination <10° or, 3) biplanar deformity: retroversion >15° and inclination >15°. Imascap SAS (Wright Medical) was used to quantify deformities and plan RSA placement. Each case was planned with the following baseplates: standard implant, three mm lateralized, wedge augment, and patient-specific implant. Each baseplate was placed in 5° of retroversion and neutral inclination and medialized to 70% seating. Percent seating, amount of reaming, global lateralization, and simulated range of motion (ROM) was recorded for each scenario.ResultsThe average patient age was 65.4 (49-78) and 14 (47%) were women. Ten of thirty (33%) were classified as Walch A1 or A2, 19/30 (63%) were B1, B2, or B3, and 1/30 (5%) was a C. The normal, uniplanar, and biplanar groups had mean retroversion deformities of 2.1° (-3- 8°), 28.4° (22-36°), and 29.3° (19-39°) respectively. Across the three cohorts, increased global lateralization through glenoid-sided lateralization provided improved ROM most significantly in adduction (R = 0.82; P <.001), flexion (R = 0.78; P <.001), and external rotation (R = 0.76; P <.001). In the nodeformity cohort, less global lateralization was needed for improved range of motion compared to uniplanar and biplanar cohorts. In uniplanar deformities, the wedge augment provided similar amounts of added global lateralization as the patient-specific augment (7.2 mm vs 8.5mm; P = .06) and was equally able to improve range of motion. In the biplanar group, the patient-specific provided greater global lateralization than wedge augment when compared to standard implants (10.1mm vs 7.1mm; P = .002) and improved ROM.ConclusionWhen RSA is used in the treatment for glenohumeral arthritis, the degree of deformity should be considered when choosing baseplate implants. Increased global lateralization is needed to optimize ROM in the setting of severe deformities and in select cases an augment wedge or patient-specific implant construct should be considered.Level of EvidenceLevel III, retrospective comparative study.     

Strategien beim Endoprothesenwechsel der Schulter

The increasing number of primary shoulder arthroplasty operations is correlated to an increasing revision rate of up to 11.2?% for anatomical shoulder arthroplasty and 13.4?% for reverse shoulder arthroplasty. To reduce the risk of implant revision the surgeon has to take the possibility of late complications into account for the index operation and to choose a modular implant system. Indications for revision arthroplasty are secondary glenoid wear, aseptic loosening, infections, rotator cuff deficiency, instability, implant malpositioning, mechanical complications and periprosthetic fractures. Due to the high rate of humeral fractures during revision surgery of anatomical stemmed implants (12?%) and reverse implants (30?%) osteotomy of the humerus is of particular importance. Osteotomy of the humeral shaft with a distal window or transhumeral shaft osteotomy as described by Gohlke can be used. The most demanding step during implantation of the revision implant is the accurate reconstruction of the prosthetic height because the stability, strength of the deltoid muscle and in unfavourable situations the degree of stiffness in the glenohumeral joint all depend on the prosthetic height. The result of anatomical glenoid revision surgery totally depends on the bony defect. Revision glenoid components showed better results compared to glenoid reconstruction using a corticocancellous bone graft but resulted in a higher rate of secondary loosening of the glenoid implant. Cementless glenoid revision implants seem to achieve a higher stability of bony fixation than cemented implants. Due to a better form closure with the reverse humeral implant and a mechanically more favorable loading of the glenoid bone stock, the glenosphere should be implanted with an inferior tilt in revision surgery.     

Reverse total shoulder arthroplasty in wheelchair-dependent patients: a matched cohort study

BackgroundShoulder function in wheelchair-dependent patients is critical for preserving independence and quality of life due to lower extremity impairment. The purpose of this study was to report the revision rate, as well as clinical and radiological outcome in wheelchair-dependent patients treated with reverse total shoulder arthroplasty (RTSA) and to compare them to an ambulating population.MethodsProspectively obtained data of 21 primary RTSAs in 17 wheelchair-dependent patients (5 male, 12 female) with a median age of 72.4 years (range: 49-80) and a minimum follow-up of 2 years were analyzed retrospectively. Revision rate, clinical (Subjective Shoulder Value = SSV, relative Constant-Murley Score = rCS, wheelchair user’s shoulder pain index = WUSPI) and radiological (glenoid loosening, scapular notching, glenoid inclination) outcome, as well as implant-related parameters (baseplate peg length, glenosphere size, bony augmentation), were compared with a 2:1 matching cohort of 42 ambulating patients (10 male, 32 female) with a median age of 72.5 years (range: 56-78).ResultsThe revision rate was 9.5% in both cohorts. In the wheelchair cohort, two shoulders had to be revised due to a complete baseplate dislocation. In the matching cohort, four shoulders had to be revised due to one prosthetic dislocation, one traumatic and one atraumatic scapular spine fracture with glenoid baseplate dislocation, and one fracture of the greater tuberosity. Median preoperative SSV and rCS did not differ significantly between cohorts. Postoperative SSV was also comparable (wheelchair: median 70 (range: 10-99) vs. matching: median 70 (30-100), p = n.s.). Relative CS was significantly lower in the wheelchair cohort (65% vs. 81.4%, P = .004). Median postoperative WUSPI was 35 points (range: 13-40) for difficulty and 0 points for pain (range: 0-29). The highest difficulty and pain were found for ‘hygiene behind the back’ and ‘propulsion of wheelchair up a ramp or on uneven surface’. Glenoid loosening, scapular notching, and postoperative baseplate inclination did not differ significantly between cohorts. In the wheelchair cohort, glenoid autograft augmentation (38.1% vs. 7.1%, P = .002) and implantation of baseplates with longer pegs were performed more often (≥ 25mm: 38.1% vs. 7.1%, P = .004).ConclusionRTSA is a valuable therapeutic option for the treatment of advanced OA or irreparable rotator cuff tears in wheelchair-bound patients with high patient satisfaction. Postoperatively, poorer function and a higher rate of baseplate dislocations might be anticipated compared to ambulating patients.     

Survivorship of a Medialized Glenoid and Lateralized Onlay Humerus Reverse Shoulder Arthroplasty Is High at Midterm Follow-up

Background

Reverse shoulder arthroplasty (RSA) is a common treatment of a variety of disabling shoulder conditions. The purpose of this study was to determine revision-free survivorship after RSA using a medialized glenoid and lateralized onlay-type humerus implant and to identify etiologies of revision.

Methods

All RSAs performed using the Comprehensive^® Reverse Shoulder System (Zimmer Biomet, Inc.; Warsaw, IN, USA) at one institution from 2008 to 2014 were identified through a retrospective review. Charts were reviewed to determine whether the RSA was a primary or revision surgery. Patients were contacted by telephone, and survivorship was defined as no subsequent surgery after RSA. Of the 526 RSAs performed, responses were obtained from 403 patients (77%). A Kaplan–Meier analysis was performed to determine survivorship over time. A χ² test was used to determine differences between revision rates after RSA.

Results

Minimum follow-up was 3 years, and average follow-up was 4.83 ± 1.60 years. Survivorship was 96% at 2 years and 93% at 5 years after RSA. Revisions were performed for instability (n = 8), humeral tray-taper junction failure (n = 5), acute fracture (n = 4), infection (n = 3), glenoid loosening (n = 3), osteolysis (n = 1), or notching (n = 1). Fourteen of the 151 patients (9.2%) who had surgery prior to RSA required revision after RSA. Having shoulder surgery prior to RSA was associated with higher rates of subsequent revision after RSA.

Conclusion

Overall, survivorship after RSA using a medialized glenoid and lateralized onlay-type humerus RSA is high, and prostheses implanted in native shoulders have lower rates of revision at midterm follow-up. Instability (1.9%) was the most common reason for revision.

     

Resurfacing of the glenoid in total shoulder arthroplasty. A comparison, at a mean of five years, of prostheses inserted with and without cement

BACKGROUND: Clinically evident loosening of a glenoid component inserted with cement in total shoulder arthroplasty is infrequent, but radiographic changes that indicate loosening at the implant-bone interface are common and have been associated with functional limitation. We compared the results of total shoulder arthroplasties in which the glenoid implant had been inserted with cement with those of arthroplasties in which a bone-ingrowth glenoid implant had been inserted without cement. METHODS: The results of eighty-six consecutive total shoulder arthroplasties, performed by the same surgeon, were retrospectively reviewed between four and seven years after the operation. Fifty-eight shoulders in which the primary glenoid implant was in situ were assessed with use of the Simple Shoulder Test and Short Form-36 questionnaires, clinical examination, and fluoroscopic imaging of the glenoid implant-bone interface. Thirty-two of the glenoid components had been fixed with cement and twenty-six, without cement. RESULTS: Complications occurred in 16 percent (fourteen) of the eighty-six shoulders, and 9 percent (eight) of the shoulders needed a revision operation. None of the revisions were done because of loosening of the glenoid component. Five of the eight revisions involved implants that had been inserted without cement. Three of these implants were revised because of early instability and two, because the polyethylene component had separated from the metal tray of the glenoid implant. With the numbers available, we could not detect any significant differences between the groups with respect to pain, range of motion, function of the shoulder, or general health. Radiographic analysis demonstrated a high level of interobserver agreement (kappa = 0.89). Radiolucent lines were observed after 41 percent (thirteen) of the thirty-two arthroplasties performed with cement compared with 23 percent (six) of the twenty-six arthroplasties performed without cement. The proportion of implants classified as probably loose was approximately three times greater in the group in which cement had been used. Eccentric wear of the posterior rim of the metal tray and focal osteolysis under the metal tray were observed in the group in which the component had been inserted without cement; these findings may indicate a potential for progression of radiographic loosening with increased durations of follow-up. CONCLUSIONS: We concluded that, despite the higher rate of early complications, the intermediate-term outcomes of arthroplasties in which the glenoid implant is inserted without cement are comparable with those of arthroplasties with cementing of the glenoid component.     

Factors affecting internal rotation after reverse shoulder arthroplasty

BackgroundThe limitation or loss of internal rotation (IR) after the surgery is a major problem in reverse shoulder arthroplasty (RSA). The particular factors associated with postoperative IR remain unclear. We aimed to analyze the predictors of IR after RSA.MethodsWe included primary RSA patients with the following implants and a minimum of 1-year follow-up: Wright Aequalis (n = 25), DJO Encore (n = 29), Biomet Comprehensive (n = 40), and Exactech Equinoxe (n = 29). Age, sex, dominant hand, primary diagnosis, implant type, preoperative critical shoulder angle, pre- and postoperative acromiohumeral distance, lateral offset of implant, glenosphere inclination, peg-glenoid rim distance (PGRD), glenosphere overhang, scapular notching, subscapularis (SSc) repair, pre- and postoperative ROM, and functional scores were assessed. IR was assessed using a 10-point scale based on the following anatomical levels: from the greater trochanter to the buttocks (2 points), from the sacrum to L4 (4 points), from L3 to L1 (6 points), from T12 to T8 (8 points), and from T7 to T1 (10 points). Univariable and multivariable analyses were performed to identify the factors affecting the IR after RSA.ResultsOne hundred twenty-three shoulders (123 patients) with a mean follow-up of 30.59 ± 19.55 (range, 12–83) months were evaluated. In the univariable analysis, preoperative diagnosis [odds ratio (OR) = 0.243, P = 0.001], implant type (P = 0.002), PGRD (OR = 1.187, P = 0.003), and preoperative IR (P < 0.001) were found to be factors associated with postoperative IR. Preoperative IR was the only factor associated with postoperative IR in the multivariable analysis (P < 0.001). Patients with preoperative IR scores of 10 or 8 points showed significantly better IR after RSA than those with preoperative IR scores of 2 or 4 points (10 points vs. 2 or 4 points; OR = 15.433, P = 0.002, 8 points vs. 2 or 4 points; OR = 6.078, P < 0.001).ConclusionPreoperative IR was the only independent factor for IR after RSA. Patients with excellent preoperative IR had better postoperative IR than those with poor preoperative IR. Preoperative diagnosis, implant type, SSc repair, implant lateralization, glenosphere inferior placement, and scapular notching were not identified as independent predictors of IR after RSA in our sample size.     

Clinical results of humeral stem lateralization in reverse shoulder arthroplasty: Comparative study of 145° onlay curved stem vs 155° inlay straight stem

BackgroundThe main limits of Grammont's reverse shoulder arthroplasty (RSA) design are loss of external rotation and scapular notching. These limits can be addressed with glenoid and/or humeral lateralization. Currently, there is no uniformity in the literature regarding the best option to improves these outcomes. Lateralization of the humeral side should be an option. The aim of the present study was to compare outcomes of a 145 degree onlay curved stem vs a 155 degree inlay straight stem.MethodsA retrospective analysis of 96 consecutive patients undergoing RSA (98 shoulders) was performed. Of these, 47 patients (48 shoulders) underwent RSA with a Aequalis Reversed II Stem (Group A) and 49 (50 shoulders) with a lateralized humeral stem (Ascend Flex©) (Group B). The exclusion criteria included any relevant glenoid bone loss in the horizontal plane or vertical plane and patients with post-traumatic conditions including humeral head necrosis. Patient with teres minor fatty infiltration superior to grade 2 according to Goutallier's classification were also excluded. Constant score, muscular strength and range of motion (ROM), were evaluated preoperatively and for 2 years postoperatively. Radiographs were examined for scapular notching.ResultsComparing clinical outcomes, there were significant improvements with active ROM using lateralized shoulder stem (Group B) in flexion, abduction and external rotation (P > .05). However, while evaluating the Constant score and muscular strength, no important difference emerged between the two groups. Scapular notching was observed in 29.17% of cases (24 shoulders) of Group A and in 12% of cases (6 shoulders) of Group B. Moreover, the average degree of notching was reduced in Group B in which the grade 1 was observed in 4 shoulders out of 50. Grade 2 was observed in 7 shoulders in Group A and in 2 shoulders in Group B. Grade 3 and grade 4 were observed only in 1 patient in Group A, and no one in Group B.ConclusionsThe lateralized humeral stem (145°, onlay, curved stem) in RSA improves ROM, particularly external rotation and abduction compared to Aequalis Reversed II Stem. No significant difference was found between the two groups regarding muscular strength. Both designs provide an overall improvement on function and pain relief. Moreover, the incidence of scapular notching is lower in a lateralized humeral stem implant (12% of cases) compared to traditional reverse prostheses with an Aequalis Reversed II Stem (29.17% of cases).Level of EvidenceIII     

Assessing glenoid arthroplasty component positioning for surgeons utilizing surgical planning software

BackgroundGlenoid component positioning remains a challenge during total shoulder arthroplasty (TSA). While preoperative three-dimensional (3D) planning software is widely available for most TSA systems today, the degree to which this software affects surgeon preoperative and intraoperative decision-making is unknown. The purpose of the study is to determine if surgeons using 3D planning software adhere to their preoperative plan and whether or not the operative plan follows glenoid component positioning guidelines for anatomic TSA (aTSA) and reverse TSA (rTSA).MethodsA total of 695 consecutive, de-identified, planned surgeries using commercially available software were identified from the case registries of six fellowship-trained shoulder arthroplasty surgeons and reviewed retrospectively. Each preoperative plan was reviewed to assess morbid glenoid version/inclination and glenoid component position. aTSA glenoid plans were evaluated for the final implant position with less than 10° of retroversion, corrective reaming less than 15°, and avoidance of glenoid vault perforation. rTSAs were evaluated for the final implant position with less than 15° of retroversion, glenosphere position in neutral or inferior tilt with at least 3 mm of inferior offset and 3 mm of posterior offset, and backside coverage of at least 50% of the baseplate on the glenoid face. Analyses were performed to determine surgeon adherence to these guidelines and variance with specific deformity patterns. Analysis of variance was performed to determine whether glenoid size resulted in selection of differing implant sizes by surgeons. The rate at which surgeon planned component size correlated with the actual implant size utilized in surgery was also evaluated.Results185 aTSAs and 510 rTSAs preoperatively planned surgeries using commercially available software were analyzed. All planning guidelines were adhered to in 90% of all aTSA cases and 79% of all rTSA cases. The concordance, or matching, between preoperative 3D planning implant selection and final implant selection was 90% for aTSA and 91% and 95% for rTSA baseplate and glenosphere implant selection, respectively. Implant size varied in accordance with glenoid size for both aTSA and rTSA (P < .001).ConclusionSurgeons adhered to known guidelines in most TSA cases when utilizing 3D computed tomography-based shoulder arthroplasty planning software. A high concordance was found between preoperative implant selection and the final glenoid component inserted. Understanding how orthopedic surgeons utilize planning software can help lead to improvements in software design.     

Finite element analysis of glenoid‐sided lateralization in reverse shoulder arthroplasty

The purpose of this study was to evaluate glenoid‐sided lateralization in reverse shoulder arthroplasty (RSA), and compare bony and prosthetic lateralization. The hypothesis was that stress and displacement would increase with progressive bony lateralization, and be lower with prosthetic lateralization. A 3D finite element analysis (FEA) was performed on a commercially available RSA prosthesis. Stress and displacement were evaluated at baseline and following 5, 10, and 15 mm of bony or prosthetic lateralization. Additional variables included glenosphere size, baseplate orientation, and peripheral screw orientation. Maximum stress for a 36 mm glenosphere without bone graft increased by 137% for the 5 mm graft, 187% for the 10 mm graft, and 196% for the 15 mm graft. Likewise, displacement progressively increased with increasing graft thickness. Stress and displacement were reduced with a smaller glenosphere, inferior tilt of the baseplate, and divergent peripheral screws. Compared to bony lateralization, stress was lower with prosthetic lateralization through the glenosphere or baseplate. Displacement with 5 mm of bony lateralization reached recommended maximal amounts for osseous integration, whereas, this level was not reached until 10–15 mm of prosthetic lateralization. Baseplate stress and displacement in an FEA model is lower with a smaller glenosphere, inferior tilt, and divergent screws. Bony lateralization increases stress and displacement to a greater degree than prosthetic lateralization. It appears that at least 10 mm of prosthetic lateralization is mechanically acceptable during RSA, but only 5 mm of bony lateralization is advised. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1548–1555, 2017.