Quantification of B2 glenoid morphology in total shoulder arthroplasty

Surgical management of biconcave glenoids: a scoping review

Biconcave (B2) glenoids, characterized by significant posterior glenoid bone loss and a biconcave wear pattern, are a challenging pathology in shoulder surgery. Significant bone defects present in B2 glenoids increases the risk of complications and rates of failure for operative patients with glenohumeral osteoarthritis. Diagnosing this entity is of pivotal importance, and can be accomplished with imaging and a comprehensive clinical investigation. There are no clear-cut guidelines for management, but options include hemiarthroplasty, anatomic total shoulder arthroplasty, and reverse shoulder arthroplasty. In recent years, modern techniques such as corrective reaming, bone grafts, and the use of augmented components have improved patient outcomes. Educating prospective patients is essential for reaching a shared management decision, setting appropriate expectations, and optimizing prognostic outcomes.

Primary and revision reverse total shoulder arthroplasty using a patient-matched glenoid implant for severe glenoid bone deficiency

BACKGROUND

Severe glenoid bone loss in the setting of both primary and revision reverse total shoulder arthroplasty (rTSA) continues to remain a significant challenge. The purpose of this study was to report on radiographic and clinical outcomes of primary and revision rTSA using a patient-matched, 3-dimensionally printed metal glenoid implant to address severe glenoid bone deficiency. This is a follow-up study to previously reported preliminary results.

METHODS

A retrospective review was performed on 62 patients with severe glenoid bone deficiency who underwent either primary or revision rTSA using the Comprehensive Vault Reconstruction System (VRS) (Zimmer Biomet) at a single institution. Preoperative and postoperative values for the Disabilities of the Arm, Shoulder and Hand (DASH), Constant, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), Simple Shoulder Test (SST), Single Assessment Numeric Evaluation (SANE), and visual analog scale (VAS) pain scores as well as active range of motion (ROM) were collected and compared using the Wilcoxon signed rank test with the level of statistical significance set at P < .05. The percentage of patients achieving minimal clinically important difference (MCID) and substantial clinical benefit (SCB) was also calculated.

RESULTS

Fifty-five of 62 shoulders (88.7%) were able to be contacted at a minimum of 2 years postoperatively, with 47 of 62 (75.8%) having complete clinical and radiographic follow-up with a mean age of 67.5 years (range, 48-85 years) and follow-up of 39.2 months (range, 25-56 months). There were 19 primary and 28 revision rTSAs. Significant improvements were seen in mean active forward flexion (63.1° ± 30.3° to 116.8° ± 35°), abduction (48.1° ± 16.1 to 76.2° ± 13.4°) (P < .001), external rotation (16° ± 23.7° to 32.1° ± 24.5°) (P < .005), DASH (59.9 ± 17.7 to 35.7 ± 24.3), Constant (23.4 ± 13.1 to 53.1 ± 17.4), ASES (27.8 ± 16.2 to 69.1 ± 25.2), SST (3.3 ± 2.5 to 7.6 ± 3.5), SANE (28.9 ± 18.3 to 66.7 ± 21.2), and VAS pain (7.1 ± 2.4 to 1.8 ± 2.6) scores (P < .001). MCID and SCB was achieved in a majority of patients postoperatively. The overall complication rate was 29.1%, with only 1 baseplate failure.

CONCLUSION

This study demonstrates promising evidence that the VRS implant can be used as a viable option to achieve clinically important improvement in a majority of patients treated for severe glenoid bone deficiency with rTSA in both the primary and revision setting.

BIO-RSA vs. metal-augmented baseplate in shoulder osteoarthritis with multiplanar glenoid deformity: a comparative study of radiographic findings and patient outcomes

BACKGROUND

Reverse shoulder arthroplasty (RSA) requiring extensive reaming to address severe glenoid bone loss increases the risk of glenoid medialization and baseplate failure. We hypothesized that (1) metal-augmented baseplate prevents the medialization of the joint line and preserves glenoid bone stock similarly to bony increased-offset (BIO)-RSA and (2) bone graft viability and healing in BIO-RSA patients become compromised over time.

MATERIALS AND METHODS

Eighty-one patients (83 shoulders) underwent glenoid lateralization with bone (BIO-RSA group, 44) or metal-augmented baseplate (metallic increased-offset [MIO]-RSA group, 39) and a minimum follow-up of 24 months were included. The orientation and direction of glenoid erosion was identified and recorded using computerized 3D planning. Active range of motion, and the Western Ontario Osteoarthritis of the Shoulder (WOOS) index were assessed before arthroplasty and at the last follow-up visits. Radiographic changes around the glenoid and humeral components were assessed. Healing and thickness of bone graft were evaluated by predefined criteria. Postoperative global glenoid inclination (β angle) and retroversion were also measured.

RESULTS

Delta scores of active anterior elevation were higher in the MIO-RSA group (P = .027). The differences in the other planes of shoulder motion and in WOOS index scores between the groups were not significant. Preoperative glenoid retroversion was higher in BIO-RSA patients, and glenoid inclination was similar in both groups. Type B2 and B3 glenoids had a posterior-central (91%) and posterior-superior (90%) erosion with a mean posterior humeral head subluxation of 76% and 78%, respectively. The direction of erosion in type E2 and E3 glenoids was posterior-superior, with a mean posterior humeral head subluxation of 74%. The rate of high position of the glenosphere was higher in the BIO-RSA group (P = .022), whereas the values of β angle and postoperative retroversion were similar in the 2 groups. BIO-RSA group showed radiolucent lines <2 mm around the bone graft in 16 patients (36.4%) and decreased thickness in 15 (34.1%). Incomplete baseplate seating was found in 4 MIO-RSA patients (10%). We found higher rates of humerus condensation lines in MIO-RSA patients (P = .01) and higher rates of cortical thinning and tuberosity resorption in the BIO-RSA group (P = .027 and P = .004, respectively).

CONCLUSION

Metal-augmented glenoid is a suitable alternative to BIO-RSA to preserve bone and prevent the medialization of the joint line in arthritic glenoid with multiplanar glenoid deformity. Bone and metal augmentation provided satisfactory clinical outcomes. Bone graft resorption in BIO-RSA patients raise concern about the risk of baseplate loosening and requires further long-term studies.

Hemiarthroplasty versus total shoulder arthroplasty in B2 glenoids with an intact rotator cuff: a long-term matched cohort analysis

Background

Walch B2 glenoids present unique challenges to the shoulder arthroplasty surgeon, particularly in young, active patients who may wish to avoid the restrictions typically associated with an anatomic total shoulder arthroplasty (TSA). Long-term data are limited when comparing hemiarthroplasty (HA) and TSA for patients with an intact rotator cuff. The purpose of our study was to compare the long-term outcomes of HA vs. TSA in a matched analysis of patients with B2 glenoids, primary osteoarthritis (OA), and an intact rotator cuff.

Methods

A retrospective review was performed of all patients who underwent HA or TSA between January 2000 and December 2011 at a single institution. Inclusion criteria were primary OA, Walch B2 glenoid morphology, an intact rotator cuff intraoperatively, at least 2 years of clinical follow-up, or revision within 2 years of surgery. Fifteen HAs met inclusion criteria and were matched 1:2 with 30 TSAs using age, sex, body mass index, and implant selection. Clinical outcomes including range of motion (ROM), visual analog scale (VAS) for pain, subjective shoulder value score, American Shoulder and Elbow Surgeons (ASES) score, complications, and revisions were recorded. Postoperative radiographs were reviewed to assess for stem loosening, humeral head subluxation, glenoid loosening, and glenoid erosion.

Results

A total of 15 HAs and 30 TSAs met inclusion criteria at a mean follow-up of 9.3 years. The mean age at the time of surgery was 60.2 years for HA and 65.4 years for TSA (P = .08). Both cohorts had significant improvements in ROM, subjective shoulder value, and VAS pain scores (P < .001). TSA had higher postoperative ASES scores compared to HA (P = .03) and lower postoperative VAS pain scores (P = .03), although the decrease in pain from preoperatively to final follow-up was not significantly different between HA and TSA (P = .11). HAs were more likely to have posterior humeral subluxation (P < .001) and stem lucencies (P = .02). Revisions occurred in 11.1% of the cohort with no difference for HA and TSA (P = .73).

Conclusions

At nearly 10 years of follow-up, HA and TSA both showed significant improvements in ROM and pain when performed for primary glenohumeral OA in B2 glenoids with intact rotator cuffs. Compared to HA, TSAs had less posterior humeral subluxation, less stem lucencies, higher ASES scores, and lower postoperative VAS pain scores. However, our study failed to demonstrate a difference in ROM, complication, or revision rates between HA and TSA.

Reverse shoulder arthroplasty with and without baseplate wedge augmentation in the setting of glenoid deformity and rotator cuff deficiency-a multicenter investigation

INTRODUCTION

Glenoid baseplate augments have recently been introduced as a way of managing glenoid monoplanar or biplanar abnormalities in reverse shoulder arthroplasty (RSA). The purpose of this study is to evaluate the difference in clinical outcomes, complications, and revision rates between augmented and standard baseplates in RSA for rotator cuff arthropathy patients with glenoid deformity.

METHODS

A multicenter retrospective analysis of 171 patients with glenoid bone loss who underwent RSA with and without augmented baseplates was performed. Preoperative inclusion criteria included minimum follow-up of 2 years and preoperative retroversion of 15°-30° and/or a beta angle 70°-80°. Version and beta angle were measured on computed tomographic scans, when available, and plain radiographs. Shoulder range of motion (ROM) and patient-reported outcomes were obtained from preoperative and multiple postoperative time points.

RESULTS

The study consisted of 84 standard baseplate patients and 87 augmented baseplate patients. The augment cohort had greater mean preoperative glenoid retroversion (17° vs. 9°, P < .001). At >5-year follow-up, the increase in postoperative active abduction (52° vs. 31°, P = .023), forward flexion (58° vs. 35°, P = .020), and internal rotation score (2.8° vs. 1.1°, P = .001) was significantly greater in the augment cohort. Additionally, >5-year follow-up American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score (87.0 ± 16.6 vs. 75.9 ± 22.4, P = .022), Constant score (78.0 ± 9.7 vs. 64.6 ± 15.1, P < .001), and Shoulder Arthroplasty Smart score (81.2 ± 6.5 vs. 71.2 ± 13.6, P = .003) were significantly higher in the augment cohort. Revision rate was low overall, with no difference between the augment and no augment groups (0.7% vs. 3.0%, P = .151).

CONCLUSION

In comparing augments to standard nonaugment baseplates in the setting of RSA with glenoid deformity, our results demonstrate greater postoperative improvements in multiple planes of active ROM in the augment cohort. Additionally, the augment cohort demonstrated greater postoperative level and improvement in scores for multiple clinical outcome metrics up to >5 years of follow-up with no difference in complication or revision rates, supporting the use of augmented glenoid baseplates in RSA with glenoid deformity.

Biconcave glenoids show 3 differently oriented posterior erosion patterns

BACKGROUND

Posterior glenoid wear remains a challenge in anatomic and reverse total shoulder arthroplasty (rTSA) because of an asymmetric erosion with altered retroversion. The purpose of this study was to assess glenoid morphology and evaluate the influence of acromial orientation in posterior glenoid erosion patterns by using 3-dimensional (3D) models.

MATERIAL AND METHODS

Computed tomographic (CT) shoulder scans from 3 study centers of patients awaiting rTSA between 2017 and 2018 were converted into 3D models and analyzed by 2 observers. Morphology, orientation and greatest depth of erosion, inclination, current retroversion and premorbid retroversion, surface areas of the glenoid, and external acromial orientation and posterior acromial slope were assessed. Measurements were compared between wear patterns, glenoid erosion entities, and genders.

RESULTS

In the complete cohort of 68 patients (63.8 ± 10.0 years; 19 female, 49 male), a mean of 85.9° (±22.2°) was observed for the glenoid erosion orientation. Additionally, a further distinct classification of the glenoid erosion as posterior-central (PC, n = 39), posterior-inferior (PI, n = 12), and posterior-superior (PS, n = 17) wear patterns was possible. These wear patterns significantly (P < .001) distinguished by erosion orientation (PC = 86.9° ± 12.0°, PI = 116.3° ± 10.3°, PS = 62.3° ± 18.9°). The greatest depth of erosion found was 7.3 ± 2.7 mm in PC wear patterns (PC vs. PI: P = .03; PC vs. PS: n.s.; PI vs. PS: n.s.). Overall, the observed erosion divided the glenoid surface into a paleoglenoid proportion of 48% (±11%) and a neoglenoid proportion of 52% (±12%). For the complete cohort, glenoid inclination was 85.4° (±6.6°), premorbid glenoid retroversion was 80.7° (±8.1°), and current glenoid retroversion was 73.4° (±7.4°), with an estimated increase of 6.9° (±6.0°). The mean external acromial orientation was 118.2° (±8.9°), and the mean posterior acromial slope was 107.2° (±9.6°). There were no further significant differences if parameters were compared by wear patterns, entities, and gender.

CONCLUSION

Three significantly differently oriented wear patterns (posterior-superior, posterior-central, and posterior-inferior) were distinguished in shoulders demonstrating posterior wear on axillary imaging. No significant differences between the observed erosion patterns or any relevant correlations were found regarding the orientation of the acromion.

Three-dimensional measures of posterior bone loss and retroversion in Walch B2 glenoids predict the need for an augmented anatomic glenoid component

HYPOTHESIS

The purpose of this study is to evaluate whether the amount of measured posterior bone loss on 2- and 3-dimensional (2D and 3D) imaging of Walch B2 glenoids can reliably predict the plan for an augmented anatomic glenoid component.

METHODS

Patients with Walch B2 glenoids and preoperative computed tomography (CT) scans were retrospectively identified. 2D axial CT scans were reviewed and posterior bone loss was measured by 3 independent reviewers. Images were then formatted into BluePrint (Wright Medical) preoperative planning software. The same 3 reviewers again measured posterior bone loss on 3D imaging. Additionally, all cases were planned with BluePrint software. An augment was used when the following criteria were unable to be satisfied with standard implants: <10° retroversion, <10° superior inclination, ≥90% backside contact, <2 mm medial reaming, and ≤1 peg perforation.

RESULTS

Forty-two patients were included in the final analysis with a mean age of 63.1 ± 6.3 years. As measured by BluePrint, the mean retroversion was 23° ± 7° (range = 9°-40°), the mean superior inclination was 5° ± 6° (range = -9° to 22°), and the mean posterior subluxation was 80% ± 17% (range = 41%-95%). The mean 2D bone loss measurements (3.5 ± 1.6 mm) were significantly lower than the mean 3D bone loss (4.0 ± 1.8 mm) measurements (P = .03). There was substantial agreement between reviewers on both 2D and 3D measurements with an interclass correlation of 0.815 (95% confidence interval [CI] 0.714-0.889, P < .001) and an interclass correlation of 0.802 (95% CI 0.683-0.884, P < .001), respectively. Augments were used in 73.8%, 63.4%, and 63.4% of cases by reviewers 1, 2, and 3, respectively, with moderate agreement with a Fleiss kappa of 0.592 (95% CI 0.416-0.769, P < .001). Augment size was moderately, positively correlated with the amount of bone loss on 3D imaging but not with 2D imaging. After multivariate logistic regression, both 3D bone loss and retroversion were found to be predictive for a plan to use an augment.

CONCLUSION

Planning for a posterior augment in Walch B2 glenoids is better predicted with 3D imaging than with 2D imaging, as 2D imaging may underestimate posterior bone loss. Additionally, use of a larger augment size is moderately correlated with posterior bone loss on 3D imaging but not 2D imaging. Standard 2D imaging may be limited in cases of posterior bone loss, and 3D imaging may be beneficial for preoperative planning in Walch B2 glenoids.

Glenoid bony morphology of osteoarthritis prior to shoulder arthroplasty: what the surgeon wants to know and why

Shoulder arthroplasty is performed with increasing frequency, and osteoarthritis is the most common indication for this procedure. However, the glenoid side of the joint is widely recognized as a limiting factor in the long-term durability of shoulder replacement, and osteoarthritis leads to characteristic bony changes at the glenoid which can exacerbate this challenge by reducing the already limited glenoid bone stock, by altering biomechanics, and by interfering with operative exposure. This article reviews the Walch classification system for glenoid morphology. Several typical findings of osteoarthritis at the glenoid are discussed including central bone loss, posterior bone loss, retroversion, biconcavity, inclination, osteophyte formation, subchondral bone quality, and bone density. The three primary types of shoulder arthroplasty are reviewed, along with several techniques for addressing glenoid deformity, including eccentric reaming, bone grafting, and the use of augmented glenoid components. Ultimately, a primary objective at shoulder arthroplasty is to correct glenoid deformity while preserving bone stock, which depends critically on characterizing the glenoid at pre-operative imaging. Understanding the surgical techniques and the implications of glenoid morphology on surgical decision-making enables the radiologist to provide the morphologic information needed by the surgeon.

Reverse Total Shoulder Arthroplasty with a Superior Augmented Glenoid Component for Favard Type-E1, E2, and E3 Glenoids

BACKGROUND

Uncorrected superior glenoid wear in patients managed with reverse total shoulder arthroplasty (rTSA) can result in increased complications, including baseplate failure. The present study quantifies the clinical and radiographic outcomes of patients with Favard type-E1, E2, and E3 glenoid deformity who were managed with rTSA with use of a superior or superior/posterior augmented glenoid baseplate.

METHODS

We retrospectively reviewed the records for 68 patients with shoulder arthritis and Favard type-E1, E2, or E3 glenoid deformity who were managed with primary rTSA and a 10° superior augmented or 10° superior/8° posterior augmented baseplate. The mean duration of follow-up was 40 months (range, 24 to 85 months). Outcomes were assessed preoperatively and at the latest follow-up with shoulder range of motion and use of outcome scores including the Simple Shoulder Test (SST), University of California Los Angeles (UCLA) score, American Shoulder and Elbow Surgeons (ASES) score, Constant score, and Shoulder Pain and Disability Index (SPADI) score. Radiographs were evaluated preoperatively and at the time of the latest follow-up. Differences in preoperative and postoperative range of motion and outcome metrics were assessed with use of a 2-tailed Student t test.

RESULTS

The majority of patients experienced clinically meaningful improvements in terms of pain and function following rTSA with a superior or superior/posterior augment, with 94% of patients rating themselves as "much better" (73.5%) or "better" (20.5%) at the time of the latest follow-up. At least 88% of the patients exceeded the minimum clinically important difference (MCID) threshold, and 75% of patients exceeded the substantial clinical benefit (SCB) threshold, for each of the clinical outcome metrics and range of motion. Five complications were reported (prevalence, 7.4%), including acromial stress fracture (2 patients), posttraumatic scapular neck fracture (1 patient), chronic shoulder pain (1 patient), and aseptic glenoid loosening (1 patient).

CONCLUSIONS

The present short-term clinical and radiographic study demonstrated that shoulder arthropathy with superior glenoid wear patterns (Favard types E1, E2, and E3) can be successfully treated with rTSA with a superior or superior/posterior augmented baseplate. Longer-term clinical and radiographic follow-up is necessary to confirm that these promising short-term results are durable.

LEVEL OF EVIDENCE

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

Early results of reverse total shoulder arthroplasty using a patient-matched glenoid implant for severe glenoid bone deficiency

BACKGROUND

Reverse total shoulder arthroplasty (rTSA) in the presence of significant glenoid bone loss remains a challenge. This study presents preliminary clinical and radiographic outcomes of primary and revision rTSA using a patient-matched, 3-dimensionally printed custom metal glenoid implant to address severe glenoid bone deficiency.

METHODS

Between September 2017 and November 2018, 19 patients with severe glenoid bone deficiency underwent primary (n = 9) or revision rTSA (n = 10) using the Comprehensive Vault Reconstruction System (VRS) (Zimmer Biomet, Warsaw, IN, USA) at a single institution. Preoperative and postoperative values for the Disabilities of the Arm, Shoulder and Hand score, Constant score, American Shoulder and Elbow Surgeons score, Simple Shoulder Test score, Single Assessment Numeric Evaluation score, and visual analog scale pain score and active range of motion were compared using the Wilcoxon signed rank test with the level of statistical significance set at P < .05.

RESULTS

Complications occurred in 4 patients (21%), including a nondisplaced greater tuberosity fracture treated conservatively in 1, intraoperative cortical perforation during humeral cement removal treated with an allograft strut in 1, and recurrent instability and hematoma formation treated with humeral component revision in 1. One patient with an early periprosthetic infection was treated with component removal and antibiotic spacer placement at an outside facility and was subsequently lost to follow-up. Eighteen patients with 1-year minimum clinical and radiographic follow-up were evaluated (mean, 18.2 months; range, 12-27 months). Significant improvements were noted in the mean Disabilities of the Arm, Shoulder and Hand score (57.4 ± 16.5 vs. 29.4 ± 19.5, P < .001), mean Constant score (24.6 ± 10.2 vs. 60.4 ± 14.5, P < .001), mean American Shoulder and Elbow Surgeons score (32 ± 18.2 vs. 79 ± 15.6, P < .001), mean Simple Shoulder Test score (4.5 ± 2.6 vs. 9.3 ± 1.8, P < .001), mean Single Assessment Numeric Evaluation score (25.4 ± 13.7 vs. 72.2 ± 17.8, P < .001), mean visual analog scale pain score (6.2 ± 2.9 vs. 0.7 ± 1.3, P < .001), mean active forward flexion (53° ± 27° vs. 124° ± 23°, P < .001), and mean active abduction (42° ± 17° to 77° ± 15°, P < .001). Mean external rotation changed from 17° ± 19° to 32° ± 24° (P = .06). No radiographic evidence of component loosening, scapular notching, or hardware failure was observed at last follow-up in any patient.

CONCLUSION

The preliminary results of rTSA using the VRS to manage severe glenoid bone deficiency are promising, but longer follow-up is necessary to determine the longevity of this implant.

Type E2 glenoid bone loss orientation and management with augmented implants

BACKGROUND

The purpose of this study was 2-fold: (1) to quantify type E2 bone loss orientation and its association with rotator cuff fatty infiltration and (2) to examine reverse baseplate designs used to manage type E2 glenoids.

METHODS

Computed tomography scans of 40 patients with type E2 glenoids were examined for pathoanatomic features and erosion orientation. The rotator cuff fatty infiltration grade was compared with the erosion orientation angle. To compare reconstructive options in light of the pathoanatomic findings, virtual implantation of 4 glenoid baseplate designs (standard, half wedge, full wedge, and patient-matched) was conducted to determine the volume of bone removal for seating and impingement-free range of motion.

RESULTS

The mean type E2 erosion orientation angle was 47° ± 17° from the 0° superoinferior glenoid axis, resulting in the average erosion being located in the posterosuperior quadrant directed toward the 10:30 clock-face position. The type E2 neoglenoid, on average, involved 67% of the total glenoid surface (total surface area, 946 ± 209 mm²; neoglenoid surface area, 636 ± 247 mm²). The patient-matched baseplate design resulted in significantly (P ≤ .01) less bone removal (200 ± 297 mm³) for implantation, followed by the full-wedge design (1228 ± 753 mm³), half-wedge design (1763 ± 969 mm³), and standard (non-augmented) design (4009 ± 1210 mm³). We noted a marked difference in erosion orientation toward a more superior direction as the subscapularis fatty infiltration grade increased from grade 3 to grade 4 (P < .001).

CONCLUSION

The average type E2 erosion orientation was directed toward the 10:30 clock-face position in the posterosuperior glenoid quadrant. This orientation resulted in the patient-matched glenoid augmentation requiring the least amount of bone removal for seating, followed by the full-wedge, half-wedge, and standard designs. Implant selection also substantially affected computationally derived range of motion in external rotation, flexion, extension, and adduction.

Clinical and radiographic outcomes with a posteriorly augmented glenoid for Walch B2, B3, and C glenoids in reverse total shoulder arthroplasty

OBJECTIVE

The purpose of this study is to quantify the clinical and radiographic outcomes of patients with severe posterior glenoid wear who were treated with reverse total shoulder arthroplasty (rTSA) and a posterior augmented baseplate.

METHODS

A total of 67 primary rTSA patients with osteoarthritis and posterior glenoid wear were treated with an 8° posterior augmented glenoid baseplate. All patients had a Walch B2, B3, or C glenoid, 2-year minimum follow-up, and mean follow-up of 40 months. All patients were scored preoperatively and at the latest follow-up using 5 clinical outcome metrics; active range of motion was also measured. A Student's 2-tailed, unpaired t-test quantified differences in outcomes, where P < .05 denoted significance.

RESULTS

All patients experienced significant improvements in pain and function after primary rTSA with a posterior augmented glenoid baseplate. Three complications were reported for a rate of 4.5%; no cases of aseptic glenoid loosening occurred. A total of 90% of patients exceeded the minimal clinically important difference threshold, and 80% of patients exceeded the substantial clinical benefit threshold for each clinical outcome metric and range of motion measure. No differences in outcomes or complications were observed between Walch B2 and B3 patients, demonstrating that this full-wedge posterior augmented baseplate was equally good in each type of glenoid deformity.

DISCUSSION

Primary rTSA patients with Walch B2, B3, and C glenoids who received an 8° posterior augmented glenoid baseplate experienced excellent clinical and radiographic outcomes with a low complication rate and no reports of aseptic glenoid loosening at a mean follow-up of 40 months.

How much bone support does an anatomic glenoid component need?

BACKGROUND

An important reason for failure of anatomic total shoulder arthroplasty is glenoid component loosening. We investigated the effect of backside bone support on the risk of failure of a glenoid component.

METHODS

A finite element model was developed. Virtual surgery was performed for 2 types of glenoid components (cemented all polyethylene [PE] vs. metal backed [MB]), both with gradually decreasing backside bone support. Both bone failure and fixation failure were analyzed. The percentages of bone failure and fixation failure in terms of the critical cement volume (CCV) and micromotion-threshold percentage ratio (MTPR) for the PE and MB components, respectively, were defined and compared.

RESULTS

For the reference PE model, the percentages of bone failure and fixation failure (CCV) were 17% and 34%, respectively. With eccentric loading for the MB component, the percentages of bone failure and fixation failure (MTPR) were 6% and 3%, respectively. A global increase in failure was observed with decreasing bone support. The increase in fixation failure, starting from the reference values (MTPR vs. CCV), was relatively more pronounced for the MB component (136% vs. 128%).

DISCUSSION

Decreasing backside bone support for an anatomic glenoid component leads to an increased risk of fixation and bone failure. For PE components, decreasing backside support to 95% bone support had only a limited effect. In the case of an MB component, we noticed an increase in micromotion and bone failure already starting from 97% bone support. We conclude that an anatomic glenoid component should always be implanted while maximizing backside bone support.

A 3-dimensional comparison of hand and power reamers in accuracy of glenoid retroversion correction

BACKGROUND

The study objective was to compare the reaming congruency of hand, power, and visual feedback axial alignment-guided (Marksman) reamers on glenoid models. We hypothesized that (1) a significant difference in average reaming deviation would be found between reamer types and (2) less ream-to-ream variation would occur with the Marksman reamer.

METHODS

Retroversion correction of 18 identical Sawbones glenoid models was conducted using either a hand, power, or Marksman reamer with a 40-mm curvature radius. Glenoid correction with either 0° or 10° reaming was conducted in triplicate sets for each reamer. Reamed glenoid computed tomography images were 3-dimensionally reconstructed using Mimics Medical software (version 21.0). Congruency between the glenoid surface and a 3-dimensional sphere with a 40-mm curvature radius was analyzed. Average deviation and ream-to-ream variance were compared between the hand, power, and Marksman reamer groups.

RESULTS

The power reamer demonstrated the smallest median deviation (0.08 mm; interquartile range [IQR], 0.07-0.19 mm), followed by the Marksman (0.09 mm; IQR, 0.08-0.17 mm) and hand (0.11 mm; IQR, 0.10-0.13 mm) reamers. Kruskal-Wallis analysis indicated no significant difference in deviation among the 3 reaming methods (P = .42). The Marksman reamer demonstrated the least variance (0.0034 mm), followed by the power (0.0076 mm) and hand (0.0093 mm) reamers. The results of the Conover squared ranks test indicated no significant difference in variance among the 3 reaming methods (P = .32).

CONCLUSION

Our findings showed no statistically significant difference in the accuracy or consistency of reaming between reamer types. Trends showed less variance in the Marksman reamer group compared with the hand and power reamer groups, although differences in variation between groups were not statistically significant.

Management of the B2 Glenoid in Glenohumeral Osteoarthritis

The Walch B2 glenoid is characterized by a biconcave glenoid deformity, acquired glenoid retroversion, and posterior humeral head subluxation. Surgical reconstruction of the B2 glenoid remains a challenge. Surgical management options include arthroscopic debridement, hemiarthroplasty, anatomic total shoulder arthroplasty with eccentric reaming, bone grafting or augmented glenoid implants, and reverse total shoulder arthroplasty. Multiple factors dictate the optimal surgical management strategy.. This article describes each of these techniques and presents the current available literature in an effort to guide evidence-based decisions in the surgical management of the B2 glenoid deformity.

Autografting for B2 Glenoids

The Walch B2 glenoid is characterized by a biconcave glenoid deformity, acquired glenoid retroversion, and posterior subluxation of the humeral head. Surgical reconstruction of the B2 glenoid is often challenging due to the complexity of the deformity. Bone graft augmentation using humeral head autograft is a valuable adjunct to anatomic total shoulder arthroplasty in the B2 glenoid, particularly in the young, highly active patient with severe glenoid retroversion (>25°–30°). Although this technique affords the ability to correct glenoid version and simultaneously enhances glenoid bone stock, it is technically challenging. The potential for graft-related complications also exists, which may further impact glenoid implant longevity and functional outcome. This review article aims to describe the B2 glenoid morphology, discuss the challenges in managing the B2 deformity, and provide further insight specifically regarding autografting at the time of anatomic total shoulder arthroplasty for reconstruction of the B2 glenoid.

Risk of Perforation Is High During Corrective Reaming of Retroverted Glenoids: A Computer Simulation Study

BACKGROUND

Corrective anterior reaming is an accepted method for addressing retroversion in a biconcave retroverted (Walch classification, type B2) glenoid in anatomic total shoulder arthroplasty. However, concern still exists regarding early glenoid component failure in the setting of severe retroversion, which may be related to loss of component containment and/or violation of subchondral bone resulting from reaming. The goal of this study was to determine what characteristics of B2 glenoids are less amenable to corrective reaming by virtually implanting anatomic glenoid components.

QUESTIONS/PURPOSES

(1) How much medial reaming is required to correct the version of a B2 glenoid to an acceptable position? (2) Are glenoids with more severe retroversion (> 25°) at higher risk of component perforation than less retroverted glenoids? (3) Is correcting to 10° of retroversion associated with greater risk as compared with reaming to 15°? (4) How does corrective reaming affect the underlying bone density on the glenoid face of B2 glenoids?

METHODS

A series of 71 patients with B2 glenoids (posterior subluxation of the humeral head with posterior bone loss) with CT scans who were indicated for shoulder arthroplasty were reviewed. Forty-four of 71 glenoids (62.5%) had < 25° of native retroversion. Anatomic glenoid implants were then virtually implanted using three-dimensional CT software that allows for preoperative shoulder arthroplasty planning to correct native retroversion to 15° or 10° of retroversion using both a central peg with an inverted triangle peg configuration or a keel. The amount of reaming of the anterior glenoid required to correct retroversion, perforation of peripheral pegs, or keel was compared. Additionally, assessment of the surface area of the glenoid that had poor bone density (defined as cancellous bone under the subchondral plate) was analyzed by the software after correction.

RESULTS

Correction to 15° of retroversion required 5 ± 3 mm of reaming, and correction to 10° of retroversion required 8 ± 3 mm of reaming to obtain at least 80% seating. Peripheral peg perforation with correction to 15° occurred in 15 of 27 (56%) glenoids with > 25° of retroversion compared with 10 of 44 (23%) of glenoids with < 25° of retroversion (relative risk [RR], 2.4; 95% confidence interval [CI], 1.3-4.6; p = 0.006). There was no difference in perforation with keeled components. Increased correction to 10° did not increase the risk of component perforation. When correction to 15°, glenoids with higher native version (> 25°) had a greater risk of poor bone quality support (10 of 27 [37%]) when compared with glenoids with less version (four of 44 [9%]; RR, 4.1; 95% CI, 1.5-12.8; p = 0.006). Increased correction resulted in 13 of 27 (48%) glenoids with version > 25° having poor bone density versus 10 of 44 (23%) with ≤ 25° of version (RR, 2.1; 95% CI, 1.1-4.1; p = 0.028).

CONCLUSIONS

There is a high risk of vault perforation after corrective reaming. Glenoid retroversions > 25° are at a higher risk of having poor bone quality supporting the component.

CLINICAL RELEVANCE

When contemplating options for patients with severe retroversion, surgeons should consider alternatives other than corrective reaming if achieving normal glenoid version is desired.

Optimizing reverse shoulder arthroplasty component position in the setting of advanced arthritis with posterior glenoid erosion: a computer-enhanced range of motion analysis

BACKGROUND

Our study purpose was to determine the optimal glenoid and humeral reverse shoulder arthroplasty (RSA) component design and position in osteoarthritic shoulders with severe glenoid retroversion deformities.

METHODS

Computed tomography scans from 10 subjects were analyzed with advanced software including RSA range of motion (ROM) analysis. Variables included glenoid component retroversion of 0°, 5°, 10°, 15°, and 20° and baseplate lateralization of 0, 5, and 10 mm. Humeral variables included 135°, 145°, and 155° angle of inclination (AOI) combined with variable humeral offset.

RESULTS

Glenoid component lateralization had the greatest influence on ROM. In comparing each ROM direction among all lateralization options independently, there were significantly greater adduction, abduction, external rotation, extension, and flexion motions with progressively greater lateralization. Internal rotation motion was greater at 10 mm only. In analyzing the effects of glenoid version independently, no differences in adduction or abduction ROM were seen. With greater retroversion, decreased external rotation and extension motion was noted; however, greater internal rotation and flexion motion was seen with the exception of flexion at 10 mm of lateralization. For adduction, external rotation, and extension, a more valgus AOI resulted in less ROM at each progressively greater AOI independent of humeral lateralization. Internal rotation and flexion motions were greater with a more varus AOI but not significant between each inclination angle. Abduction ROM was maximized with a more valgus AOI. Humeral lateralization had no effect on ROM.

CONCLUSIONS

In the setting of RSA for advanced glenoid osteoarthritic deformities, optimal ROM is achieved with 10-mm baseplate lateralization and neutral to 5° of retroversion mated to a humeral implant with a varus (135°) inclination angle.

Radiographic results of augmented all-polyethylene glenoids in the presence of posterior glenoid bone loss during total shoulder arthroplasty

BACKGROUND

Chronic osteoarthritis can result in glenohumeral subluxation and loss of posterior glenoid bone. This can alter normal glenohumeral biomechanics and affect the stress placed on the glenoid implant after total shoulder arthroplasty. This study evaluated the clinical and radiographic results of an augmented all-polyethylene glenoid for the treatment of glenoid osteoarthritis in the presence of posterior glenoid bone loss and determined whether any failures or complications occurred with short-term follow-up.

METHODS

During a 2-year period, 21 patients were treated with an augmented glenoid for an index diagnosis of osteoarthritis with a biconcave glenoid and average posterior glenoid bone loss of 4.7 mm. Clinical outcomes were recorded for the American Shoulder and Elbow Surgeons Shoulder Assessment, Simple Shoulder Test, and active motion. Radiographic analysis included glenoid version, humeral head subluxation, component seating, ingrowth, and loosening.

RESULTS

Significant improvements were demonstrated for American Shoulder and Elbow Surgeons Shoulder Assessment (52.3), Simple Shoulder Test (8.1), forward flexion (50°), external rotation (32°), and pain. Radiographic improvements were found for glenoid version (12°), humeral scapular alignment (23%), and humeral glenoid alignment (8%). Central peg ingrowth was demonstrated in all patients, and complete component seating was achieved in 19 patients. No complications were encountered, and no clinical or radiographic failures were identified.

CONCLUSION

Augmented polyethylene glenoid components demonstrated improved clinical outcome, without implant failure or complications, during short-term follow-up.

Quantitative assessment and characterization of glenoid bone loss in a spectrum of patients with glenohumeral osteoarthritis

PURPOSE

Eccentric posterior bone loss and associated glenoid retroversion represent challenges to glenoid placement during total shoulder arthroplasty. This bone loss can lead to poor stability and perforation of the glenoid during arthroplasty. The purpose of this study was to evaluate the morphology of glenoid bone loss for a spectrum of osteoarthritis patients using 3D computed tomography imaging and simulation software.

METHODS

This study included 29 patients with glenohumeral osteoarthritis treated with shoulder arthroplasty. Three-dimensional reconstruction of preoperative CT images was performed. Glenoid bone loss was measured at ten, vertically equidistant axial planes along the glenoid surface at four distinct anterior-posterior points on each plane. The images were fitted with modeled pegged glenoid implants to predict glenoid perforation.

RESULTS

The 3D maps demonstrated greatest average bone loss posteriorly in the AP plane at the central axis of the glenoid in the SI plane. The average amount of bone loss was 3.85 mm. Walch A2 and B1 shoulders showed more central bone loss, while Walch B2 shoulders displayed more posterior and inferior bone loss. Patients with predicted peg perforation displayed significantly greater bone loss than those without predicted peg perforation (p = 0.037). Peg perforation was most common in Walch B2 shoulders occurring in the posterior direction involving the central and posterior-inferior peg.

CONCLUSIONS

These data demonstrate an anatomic pattern of glenoid bone loss for different classes of glenohumeral arthritis. These findings can be used to develop various models of glenoid bone loss to guide surgeons, predict failures, and develop better glenoid implants. This study has been approved by the Cleveland Clinic IRB: Number 6235.

A comparison of normal and osteoarthritic humeral head size and morphology

BACKGROUND

The purpose of this study was to evaluate and to compare the size and morphologic patterns among normal and osteoarthritic (OA) humeral heads.

METHODS

This comparative anatomic imaging study evaluated 150 humeral heads that were separated into 3 cohorts: normal, OA with symmetric glenoid erosion, and OA with asymmetric (type B2) glenoid erosion. Three-dimensional models were created of the humeral head from computed tomography data, and point coordinates were extracted for evaluation. Parameters measured were diameter (sphere fit and circle fit), chord distance (superoinferior and anteroposterior), and humeral head height.

RESULTS

The sphere-fit diameter of the humeral head for the entire OA cohort (100 patients; mean diameter, 59 ± 9 mm) was significantly greater (P < .001) than that of the normal cohort (50 patients; mean diameter, 49 ± 5 mm). Similarly, the humeral head circle-fit diameters in the superoinferior and anteroposterior planes were significantly greater (P < .001) in the combined OA cohorts (59 ± 9 mm and 56 ± 10 mm, respectively) compared with the normal cohort (51 ± 5 mm and 47 ± 5 mm, respectively). However, there were no significant differences (P ≥ .099) between the symmetric and asymmetric OA cohorts in sphere-fit or circle-fit diameters. The mean values of humeral head heights were not significantly different (P = .382) between cohorts, 19 ± 2 mm, 18 ± 2 mm, and 18 ± 2 mm for the normal, symmetric, and asymmetric cohorts, respectively.

DISCUSSION

Although OA humeral head morphology varies significantly from normal, it does not vary as a function of the Walch classification between symmetric and asymmetric glenoids. Understanding of the morphologic variability of the pathologic humeral head may provide insight into the pathoanatomy of osteoarthritis and the development of various erosion patterns.

The arthritic glenoid: anatomy and arthroplasty designs

The number of shoulder arthroplasty procedures has increased dramatically in recent years, with the primary indication being osteoarthritis (OA). Thus, morphology and subchondral bone changes associated with OA may be important factors to consider when choosing a replacement component. For surgical treatment, many implant options exist and survivability is often dependent on patient age, activity level, and progression of OA. In the placement of these replacement components, patient-specific guides now exist to improve component positioning, with the goal to improve long-term survivability by ensuring that intra-operative placement meets component design.