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Understanding the mechanical properties of trabecular bone within the metaphysis of the proximal humerus is becoming increasingly important for the design of humeral head joint replacement components that prioritize bone preservation. The aim of this study was to perform full-field mechanical testing methods on isolated trabecular bone cores from the humeral head to experimentally measure the local magnitude of strain before macroscopic failure and to characterize the ultimate strength of each core. Isolated cubic trabecular bone cores were extracted from the center of humeral head osteotomies retrieved from (1) patients with end-stage osteoarthritis (OA) undergoing total shoulder arthroplasty (TSA) and (2) normal nonpathologic cadaveric humeral heads. A custom computed tomography (CT)-compatible loading device was used to perform compressive mechanical testing. For 10 of the OA specimens, stepwise loading was performed directly within a microCT scanner and digital volume correlation (DVC) was used to measure full-field strains throughout the trabecular structure. A higher variability in ultimate strength was measured for the trabecular cores retrieved from OA humeral heads (range: 2.8-7.6 MPa) compared to the normal cadaveric humeral heads (range: 2.2-5.4 MPa), but no statistically significant difference between the groups was found (p = 0.06). Ultimate strength was strongly correlated with bone volume fraction (OA r 2  = 0.72; normal r 2  = 0.76) and bone mineral content (OA r 2  = 0.79; normal r 2  = 0.77). At the trabecular level, 95th percentile of third principal strains, measured at a subvolume size of 152 µm, exceeded 19,000 µε for each of the 10 specimens (range: -19,551 to -36,535 µε) before macroscopic failure of the cores occured. No strong linear correlations (r 2  ≥ 0.50) were found between the median or 95th percentile of DVC third principal strain and the corresponding morphometric parameters of each individual bone core. The results of this study indicate that bone volume fraction and bone mineral content heavily influence the apparent ultimate strength of trabecular bone cores collected from OA patients undergoing TSA. Clinical significance: The strong correlations observed within this study further emphasize the importance of considering bone mineral content or bone volume fraction measurements in assessing the localized risk of trabecular bone fracture for orthopedic applications., (© 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Understanding the local mechanical properties of trabecular bone at the humeral head-neck junction is essential for the safe design of stemless humeral head implants. Recent advancements in mechanical testing coupled with volumetric imaging have allowed for the ability to quantify full-field strain distributions throughout trabecular bone. Within this study, digital volume correlation (DVC) was applied to micro-computed tomography images to investigate the local load carrying characteristics of trabecular bone within osteoarthritic (OA) humeral heads subjected to stepwise loading. A multi-pegged indenter was used to transfer loads from a custom-fabricated loading apparatus to trabecular bone on the resection surface of OA humeral head osteotomies retrieved from patients undergoing total shoulder arthroplasty (TSA). In regions of trabecular bone that eventually fractured, third principal strains were significantly higher (95 th percentile third principal strain = -12,558 μstrain, p < 0.001) compared to regions that did not fracture (95 th percentile third principal strain = -7,806 μstrain). As well, bone volume fraction (p = 0.012), trabecular separation (p = 0.014), and trabecular number (p = 0.007) were found to influence the likelihood of trabecular bone fracture. Collectively, this work has led to a deeper understanding of the local load carrying characteristics of trabecular bone specific to patients receiving TSA for osteoarthritis., (Crown Copyright © 2021. Published by Elsevier Ltd. All rights reserved.)

Background: The etiology of the Walch type B shoulder remains unclear. We hypothesized that a scapulohumeral muscle imbalance, due to a disturbed transverse force couple (TFC) between the anterior and posterior rotator cuff muscles, may have a role in the pathogenesis of the type B morphology. The purpose of this study was to determine whether there is a TFC imbalance in the Walch type B shoulder using an imaging-based 3-dimensional (3D) volumetric and fatty infiltration assessment of segmented rotator cuff muscles., Methods: Computed tomography images of 33 Walch type A and 60 Walch type B shoulders with the complete scapula and humerus including the distal humeral epicondyles were evaluated. The 3D volumes of the entire subscapularis, supraspinatus, and infraspinatus-teres minor (Infra-Tm) were manually segmented and analyzed. Additionally, anthropometric parameters including glenoid version, glenoid inclination, posterior humeral head subluxation, and humeral torsion were measured. The 3D muscle analysis was then compared with the anthropometric parameters using the Wilcoxon rank sum and Kruskal-Wallis tests., Results: There were no significant differences (P > .200) in muscle volume ratios between the Infra-Tm and the subscapularis in Walch type A (0.93) and type B (0.96) shoulders. The fatty infiltration percentage ratio, however, was significantly greater in type B shoulders (0.94 vs. 0.75, P < .001). The Infra-Tm to subscapularis fatty infiltration percentage ratio was significantly larger in patients with >75% humeral head subluxation than in those with 60%-75% head subluxation (0.97 vs. 0.74, P < .001) and significantly larger in patients with >25° of retroversion than in those with <15° of retroversion (1.10 vs. 0.75, P = .004). The supraspinatus fatty infiltration percentage was significantly lower in Walch type B shoulders than type A shoulders (P = .004). Walch type A shoulders had mean humeral retrotorsion of 22° ± 10° whereas Walch type B shoulders had humeral retrotorsion of only 14° ± 9° relative to the epicondylar axis (P < .001)., Conclusion: The TFC is in balance in the Walch type B shoulder in terms of 3D volumetric rotator cuff muscle analysis; however, the posterior rotator cuff does demonstrate increased fatty infiltration. Posterior humeral head subluxation and glenoid retroversion, which are pathognomonic of the Walch type B shoulder, may lead to a disturbance in the length-tension relationship of the posterior rotator cuff, causing fatty infiltration., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: An assessment of the pathoanatomic parameters of the arthritic glenohumeral joint (GHJ) has the potential to identify discriminating metrics to differentiate glenoid types in shoulders with primary glenohumeral osteoarthritis (PGHOA). The aim was to identify the morphometric differences and threshold values between glenoid types including normal and arthritic glenoids with the various types in the Walch classification. We hypothesized that there would be clear morphometric discriminators between the various glenoid types and that specific numeric threshold values would allow identification of each glenoid type., Methods: The computed tomography scans of 707 shoulders were analyzed: 585 obtained from shoulders with PGHOA and 122 from shoulders without glenohumeral pathology. Glenoid morphology was classified according to the Walch classification. All computed tomography scans were imported in a dedicated automatic 3D-software program that referenced measurements to the scapular body plane. Glenoid and humeral modeling was performed using the best-fit sphere method, and the root-mean-square error was calculated. The direction and orientation of the glenoid and humerus described glenohumeral relationships., Results: Among shoulders with PGHOA, 90% of the glenoids and 85% of the humeral heads were directed posteriorly in reference to the scapular body plane. Several discriminatory pathoanatomic parameters were identified: GHJ narrowing < 3 mm was a discriminatory metric for type A glenoids. Posterior humeral subluxation > 70% discriminated type B1 from normal GHJs. The root-mean-square error was a discriminatory metric to distinguish type B2 from type A, type B3, and normal GHJs. Type B3 glenoids differed from type A2 by greater retroversion (>13°) and subluxation (>71%). The type C glenoid retroversion inferior limit was 21°, whereas normal glenoids never presented with retroversion > 16°., Conclusion: Pathoanatomic metrics with the identified threshold values can be used to discriminate glenoid types in shoulders with PGHOA., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Preoperative radiographic assessment of osteophyte and loose body locations is critical in planning an arthroscopic débridement for primary elbow osteoarthritis. The purpose of this study was to evaluate the effectiveness of radiographs and computed tomography (CT) in localizing osteophytes and loose bodies., Methods: A consecutive series of 36 patients with primary elbow osteoarthritis was investigated with radiographs and multiaxial 2-dimensional CT prior to elbow arthroscopy. The location of osteophytes and loose bodies was assessed in 9 anatomic locations by 2 fellowship-trained upper extremity surgeons. The diagnostic effectiveness of both imaging modalities was evaluated by calculating the sensitivity and specificity and compared to the gold standard of elbow arthroscopy. Inter- and intrarater percentage agreement between the observations was calculated using Kappa score., Results: The mean sensitivity for detecting osteophytes in the 9 different anatomic locations was 46% with radiographs and 98% with CT, whereas the mean specificity was 66% and 21% for radiographs and CT, respectively. The mean sensitivity and specificity for loose body detection with radiography were 49% and 89%, respectively, whereas CT had a mean sensitivity of 98% and specificity of 47%. The overall inter-rater percentage agreement between the surgeons in detecting osteophytes and loose bodies on radiographs was 80% and 85%, respectively, whereas on CT it was 95% for detecting osteophytes and 91% for loose bodies., Conclusion: CT has greater sensitivity than radiographs for the detection of osteophytes and loose bodies in primary elbow osteoarthritis. The lower specificity of CT may be due to this imaging modality's ability to detect small osteophytes and loose bodies that may not be readily identified during elbow arthroscopy. Radiographs have an inferior inter-rater percentage agreement compared with CT. CT is a valuable preoperative investigation to assist surgeons in identifying the location of osteophytes and loose bodies in patients undergoing surgery for primary elbow osteoarthritis., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.)

Continuum-level finite element models (FEMs) of the humerus offer the ability to evaluate joint replacement designs preclinically; however, experimental validation of these models is critical to ensure accuracy. The objective of the current study was to quantify experimental full-field strain magnitudes within osteoarthritic (OA) humeral heads by combining mechanical loading with volumetric microCT imaging and digital volume correlation (DVC). The experimental data was used to evaluate the accuracy of corresponding FEMs. Six OA humeral head osteotomies were harvested from patients being treated with total shoulder arthroplasty and mechanical testing was performed within a microCT scanner. MicroCT images (33.5 µm isotropic voxels) were obtained in a pre- and post-loaded state and BoneDVC was used to quantify full-field experimental strains (≈ 1 mm nodal spacing, accuracy = 351 µstrain, precision = 518 µstrain). Continuum-level FEMs with two types of boundary conditions (BCs) were simulated: DVC-driven and force-driven. Accuracy of the FEMs was found to be sensitive to the BC simulated with better agreement found with the use of DVC-driven BCs (slope = 0.83, r 2 = 0.80) compared to force-driven BCs (slope = 0.22, r 2 = 0.12). This study quantified mechanical strain distributions within OA trabecular bone and demonstrated the importance of BCs to ensure the accuracy of predictions generated by corresponding FEMs.

Osteoarthritis (OA) is characterized by morphological changes that alter bone structure and mechanical properties. This study compared bone morphometric parameters and apparent modulus between humeral heads excised from end-stage OA patients undergoing total shoulder arthroplasty (n = 28) and non-pathologic normal cadavers (n = 28). Morphometric parameters were determined in central cores, with regional variations compared in four medial to lateral regions. Linear regression compared apparent modulus, morphometric parameters, and age. Micro finite element models estimated trabecular apparent modulus and derived density-modulus relationships. Significant differences were found for bone volume fraction (p < 0.001) and trabecular thickness (p < 0.001) in the most medial regions. No significant differences occurred between morphometric parameters and apparent modulus or age, except in slope between groups for apparent modulus versus trabecular number (p = 0.021), and in intercept for trabecular thickness versus age (p = 0.040). Significant differences occurred in both slope and intercept between density-modulus regression fits for each group (p ≤ 0.001). The normal group showed high correlations in the power-fit (r 2  = 0.87), with a lower correlation (r 2  = 0.61) and a more linear relationship, in the OA group. This study suggests that alterations in structure and apparent modulus persist mainly in subchondral regions of end-stage OA bone. As such, if pathologic regions are removed during joint replacement, computational models that utilize modeling parameters from non-pathologic normal bone may be applied to end-stage OA bone. An improved understanding of humeral trabecular bone variations has potential to improve the surgical management of end-stage OA patients. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:503-509, 2020., (© 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Background: The Walch type B glenoid has the hallmark features of retroversion, joint subluxation, and bony erosion. Although the type B glenoid has been well described, the morphology of the corresponding type B humerus is poorly understood. As such, the aim of this imaging-based anthropometric study was to investigate humeral torsion in Walch type B shoulders., Methods: Three-dimensional models of the full-length humerus were generated from computed tomography data for the Walch type B group (n = 59) and for a control group of normal nonarthritic shoulders (n = 59). An anatomic humeral head-neck plane was created and used to determine humeral torsion relative to the epicondylar axis. Measurements were repeated, and intraclass correlation coefficients were calculated., Results: The type B humeri had significantly (P < .001) less retrotorsion (14° ± 9°) than the control group (36° ± 12°) relative to the epicondylar axis. Male and female individuals within the control group showed statistically significant differences in humeral torsion (P = .043), which were not found in the type B group. Inter-rater reliability showed excellent agreement for humeral torsion (intraclass correlation coefficient, 0.962). A subgroup analysis between Walch type B2 and B3 shoulders showed no significant differences in any of the humeral or glenoid parameters., Conclusion: The Walch type B humerus has significantly less retrotorsion than non-osteoarthritic shoulders. At present, it is unknown whether the altered humeral retrotorsion is a cause or effect of the type B glenoid. In addition, it is unknown whether surgeons should be reconstructing type B2 humeral component version to pathologic torsion or to nonpathologic population means to optimize arthroplasty survivorship., (Copyright © 2019 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Glenohumeral offset (GHO) may change from the preoperative state after anatomic total shoulder arthroplasty (TSA), and has been identified as a factor that may affect shoulder mechanics, strength, and function. The primary objective was (1) to establish a reliable method of measuring GHO with standardized computed tomography (CT) imaging planes and (2) to determine whether an association exists between GHO and functional outcomes in TSA., Methods: Thirty-seven patients underwent TSA for glenohumeral osteoarthritis. Preoperative and postoperative CT scans were reformatted along standardized measurement planes for the glenoid and humerus separately. Inter-rater and intrarater reliability was determined for 3 methods to measure humeral offset and 2 methods to measure glenoid offset. Univariate regression analysis was used to determine the association between GHO and functional outcomes including the Constant score and strength., Results: Of all methods tested, the highest preoperative and postoperative inter-rater reliability was r = 0.84 and r = 0.8, and r = 0.7 and r = 0.8 for humeral and glenoid offset, respectively. Intrarater reliability was >0.94. There was a mean increase of 4.3 mm (standard deviation, 4.6; range, -10.6 to 10.8) in combined GHO from preoperative to postoperative time points. No associations were observed between change in offset and functional or strength scores., Discussion: A reliable approach to measure prearthroplasty and postarthroplasty GHO with CT plane standardization has been described. A net increase in GHO was observed after TSA. No associations were found between change in offset after TSA and functional scores or strength up to 2 years postoperatively., (Copyright © 2019 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The Walch classification describes glenoid morphology in primary arthritis. As knowledge grows, several modifications to the classification have been proposed. The type D, a recent modification, was defined as an anteverted glenoid with or without anterior subluxation. Literature on the anteverted glenoid in primary osteoarthritis is limited. The purpose of this study, therefore, was to analyze the anatomic characteristics of the type D glenoid on radiographs and computed tomography (CT)., Methods: The shoulder arthroplasty databases from 3 institutions were examined to identify patients with primary glenohumeral osteoarthritis and glenoid anteversion (≥5°), with or without anterior subluxation. The type D study cohort consisted of 18 patients (3% of the osteoarthritis cohort) and was a mean of 70 years old, with 11 women and 7 men. All radiographs were reviewed, and computed tomography Digital Imaging and Communications in Medicine (National Electrical Manufacturers Association, Rosslyn, VA, USA) data were analyzed on validated 3-dimensional imaging software. Rotator cuff fatty infiltration, glenoid measurements (anteversion and inclination), and humeral head subluxation according to the scapular plane were determined., Results: In the study cohort, the mean glenoid anteversion was 12° (range, 5°-24°), the mean inclination was 0°, and the mean anterior subluxation was 38% (range, 6%-56%). Eight patients (44%) had a biconcave glenoid with a posterosuperiorly positioned paleoglenoid and an anteroinferiorly positioned neoglenoid, and 10 patients had a monoconcave glenoid. Fatty infiltration of the rotator cuff muscles never exceeded Goutallier stage 2., Conclusion: The type D glenoid is an addition to the original Walch classification and is characterized by glenoid anteversion (≥5°), anteroinferior humeral head subluxation, and absence of severe subscapularis fatty infiltration., (Copyright © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.)

Background: The type B3 glenoid is an addition to the Walch classification. A potential etiologic theory is that it is a progression of the B2. It is characterized by uniconcavity, absent paleoglenoid, medialization, retroversion, and subluxation. The purpose of this study was to describe the morphology of B3 glenoids., Methods: Fifty-two patients with B3 glenoids underwent 3-dimensional analysis of computed tomography data. Glenoid measurements (retroversion, inclination, medialization) and humeral head subluxation according to the scapular and glenoid planes were determined. The measured variables were compared between male and female patients., Results: The mean B3 retroversion, inclination, and medialization were 24° ± 7°, 8° ± 6° superior, and 14 ± 4 mm, respectively. The mean posterior subluxation was 80% ± 8% and 54% ± 6% according to the scapular and glenoid planes, respectively. There were no differences in B3 characteristics between sexes (P > .05). A significant correlation existed between glenoid retroversion and humeral head subluxation relative to the scapular plane, with every 1° increase in retroversion translating to a 1% increase in subluxation (P < .001). In contrast, when referencing the glenoid plane, the humeral head remained concentric to the erosion., Conclusions: The B3 is uniconcave and retroverted. As glenoid retroversion increases, posterior humeral head subluxation significantly increases as referenced to the scapular plane; however, when referenced to the glenoid plane, the head remains concentric to the erosion. This appearance of "concentricity" is acquired secondary to the wear pattern, creating a uniconcave glenoid. Therefore, surgeons should be aware that the visualized concentricity is a product of the erosion pattern and thus may conceal a greater amount of subluxation potential., (Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Posterior glenoid erosion is thought to be initiated by humeral head subluxation. However, it is unknown whether subluxation is entirely caused by soft-tissue instability and unbalanced muscle activity or whether osseous morphology is a contributing factor. We hypothesized that patients with posterior erosion may exhibit premorbid glenoid morphology that is inherently retroverted and inferiorly inclined compared with age-matched normal glenoids., Methods: This study examined 80 scapulae, evenly distributed between 2 groups: osteoarthritic with type B2 glenoids and age-matched normal glenoids. From 3-dimensional computed tomography reconstructions, version and inclination were measured from the anterior paleoglenoid region of the B2 glenoids, which is representative of the premorbid glenoid, and compared with measurements obtained from similar regions in the normal cohort., Results: The anterior paleoglenoid region of B2 glenoids was significantly (P < .001) more retroverted (-14° ± 6°) compared with similar regions in nonarthritic normal glenoids (-5° ± 5°). There were no significant differences (P = .166) in the glenoid inclination angle between type B2 glenoids (0° ± 6°) and nonarthritic normal glenoids (2° ± 5°). Negative values represent retroverted and inferiorly inclined glenoids., Discussion: Understanding premorbid glenoid morphologic variations may provide insight into the pathoanatomy of humeral head subluxation, osteoarthritis, and posterior glenoid erosion. The results of this study indicate that patients with type B2 osteoarthritic glenoids have significantly greater premorbid glenoid retroversion compared with nonarthritic normal glenoids, suggesting that this premorbid morphologic variation may be one contributing factor to posterior erosion., (Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The purpose of this computational modeling study was to compare the volume of glenoid bone removal required to implant 3 augmented component designs for management of B2 erosions. In addition, we assessed bone quality of the supporting bone directly beneath the implants by measuring bone density and porosity., Methods: Three augmented component designs—full-wedge, posterior-wedge, and posterior-step—were studied by virtual implantation in a cohort of 16 patients with B2 glenoids. B2 retroversion was corrected to 0° and 10°. The outcome variables were the volume of glenoid bone removal required for implantation and the density and porosity of the bone immediately beneath the implant., Results: Implant design had a significant effect on the volume of bone removal (P < .001). When correcting to 0°, the posterior-wedge implant removed less bone than the posterior-step (P < .001) and the full-wedge (P = .004). At 10° retroversion, the posterior-wedge removed less bone (P = .029) than the posterior-step but was no different than the full-wedge (P = .143). The residual glenoid bone density with the posterior-wedge was significantly greater than with the posterior-step (P = .048), with no other significant differences (P > .05). Residual glenoid bone porosity was not significantly different between implants (P > .262)., Conclusions: Augmented components can provide a bone-preserving option for B2 glenoid management. Substantial variations in the volume of bone removal and the quality of the remaining glenoid bone were found between 3 different designs of augmented implants. Simulations with the posterior-wedge implant resulted in substantially less glenoid bone removal, with the remaining supporting bone being of better quality., (Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The purpose of this computed tomography-based study was to quantify erosions in B2 glenoids. We hypothesized that erosions do not occur symmetrically and that they have a predictable orientation., Methods: This study evaluated 55 type B2 glenoid cases. Computed tomography data were used to create three-dimensional reconstructions, and point coordinates were extracted from each reconstruction for morphologic analysis of the osteoarthritic glenoid and humerus., Results: There was a significant difference between the mean orientation angle (28° ± 11°) of the posterior glenoid line of erosion and the superoinferior axis (P < .001), which resulted in the average erosion being directed toward the 8-o'clock position. On average, the erosion started 1.6 ± 3.4 mm posterior to the glenoid center point. In 35% of B2 cases, the line of erosion was curved. The mean surface area was 763 ± 296 mm(2) for the neoglenoid and 957 ± 276 mm(2) for the paleoglenoid, indicating that the neoglenoid occupied 44% ± 12% of the total glenoid area. In this cohort, the mean radius of the humeral head neoarticulation was 32 ± 6 mm, the neoglenoid radius was 37 ± 8 mm, and the paleoglenoid radius was 34 ± 7 mm. The radius of the humeral head was significantly less than that of the neoglenoid (P < .001) and the paleoglenoid (P = .009). In addition, the radius of the neoglenoid was significantly greater than the radius of the paleoglenoid (P = .012)., Discussion: Type B2 glenoids have a predictable wear pattern, which is not axisymmetric to the glenoid superoinferior axis. In addition, the identified anatomic characteristics of B2 erosions will aid surgeons in the operative management of bone loss and may assist manufacturers in the design of augmented components., (Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Accurate characterization of regional variations in bone density in symmetric and asymmetric (B2) glenoid erosion patterns can assist with surgical planning, reaming, and component implantation. The purpose of this study was to characterize regional bone density and porosity in symmetric and asymmetric (B2) osteoarthritic glenoids., Methods: Symmetric (n = 25) and asymmetric (B2) (n = 25) erosion patterns were compared by computed tomography-based imaging software. An orthogonal coordinate system separated each glenoid into quadrants. In addition, a linear best-fit line defined the line-of-erosion between the paleoglenoid and neoglenoid in the asymmetric cohort. All glenoids were further divided into volumes at depths of 0 to 2.5 mm and 2.5 to 5 mm. Average bone density was measured in Hounsfield units. Bone voids or cysts were included to quantify regional porosity as the fraction of void volume to total glenoid volume., Results: For the symmetric cohort, there were no significant differences in bone density between quadrants at either depth (P ≥ .089). For the asymmetric cohort, bone density was significantly higher in the posterior quadrants compared with the anterior quadrants (P < .001), especially posteroinferiorly (P ≤ .007) at both depths. In addition, the neoglenoid had significantly higher density and lower void fraction compared with the paleoglenoid (P < .001). There were also significant differences in void fraction between quadrants for both cohorts, at both depths (P ≤ .004)., Conclusions: This study demonstrates that osteoarthritic glenoids with symmetric erosion have uniform subarticular bone density. However, asymmetric (B2) erosion patterns have potentially important regional variations in bone density and porosity, with the densest bone with the least porosity found posteroinferiorly or in the neoglenoid region., (Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

We assessed the clinical results, radiographic outcomes and complications of patients undergoing total shoulder replacement (TSR) for osteoarthritis with concurrent repair of a full-thickness rotator cuff tear. Between 1996 and 2010, 45 of 932 patients (4.8%) undergoing TSR for osteoarthritis underwent rotator cuff repair. The final study group comprised 33 patients with a mean follow-up of 4.7 years (3 months to 13 years). Tears were classified into small (10), medium (14), large (9) or massive (0). On a scale of 1 to 5, pain decreased from a mean of 4.7 to 1.7 (p = < 0.0001), the mean forward elevation improved from 99° to 139° (p = < 0.0001), and the mean external rotation improved from 20° (0° to 75°) to 49° (20° to 80°) (p = < 0.0001). The improvement in elevation was greater in those with a small tear (p = 0.03). Radiographic evidence of instability developed in six patients with medium or large tears, indicating lack of rotator cuff healing. In all, six glenoid components, including one with instability, were radiologically at risk of loosening. Complications were noted in five patients, all with medium or large tears; four of these had symptomatic instability and one sustained a late peri-prosthetic fracture. Four patients (12%) required further surgery, three with instability and one with a peri-prosthetic humeral fracture. Consideration should be given to performing rotator cuff repair for stable shoulders during anatomical TSR, but reverse replacement should be considered for older, less active patients with larger tears.

Computer models capable of predicting elbow flexion and extension range of motion (ROM) limits would be useful for assisting surgeons in improving the outcomes of surgical treatment of patients with elbow contractures. A simple and robust computer-based model was developed that predicts elbow joint ROM using bone geometries calculated from computed tomography image data. The model assumes a hinge-like flexion-extension axis, and that elbow passive ROM limits can be based on terminal bony impingement. The model was validated against experimental results with a cadaveric specimen, and was able to predict the flexion and extension limits of the intact joint to 0° and 3°, respectively. The model was also able to predict the flexion and extension limits to 1° and 2°, respectively, when simulated osteophytes were inserted into the joint. Future studies based on this approach will be used for the prediction of elbow flexion-extension ROM in patients with primary osteoarthritis to help identify motion-limiting hypertrophic osteophytes, and will eventually permit real-time computer-assisted navigated excisions.

Purpose: To determine the locations and volumes of bone requiring resection to restore range of motion in patients with osteoarthritis of the elbow, using computational modeling., Methods: A total of 30 patients with primary osteoarthritis of the elbow and restricted range of motion underwent computed tomography. We used the computed tomography data to generate 3-dimensional models. We simulated flexion and extension of the elbow by flexing and extending the radius and ulna about the flexion-extension axis. The locations and volumes of impinging bone were calculated by the model at flexion angles of 0°, 10°, 20°, 120°, 130°, and 140°., Results: Flexion simulations demonstrated bony overlap in many patients between the coronoid process and the coronoid fossa and between the radial head and the radial fossa. The volumes of these overlapping regions increased as the flexion angle increased. Extension simulations demonstrated bony overlap between the tip and sides of the olecranon and the corresponding regions of the olecranon fossa in most patients. These overlapping volumes increased in greater degrees of elbow extension. In addition, we found bony overlap in extension in several patients between the radial head and an osteophyte present on the posterior aspect of the capitellum. The mean total overlapping volumes at each flexion angle were 59 mm(3) at 120°, 238 mm(3) at 130°, and 589 mm(3) at 140° in flexion; and 184 mm(3) at 20°, 395 mm(3) at 10°, and 741 mm(3) at 0° in extension., Conclusions: Three-dimensional computational models identified the locations and volumes of bony impingement in patients with osteoarthritis of the elbow. They also highlighted certain unique regions of impingement, such as between the radial head with a posterior capitellar osteophyte in extension., Clinical Relevance: This modeling approach may provide the surgeon with a useful patient-specific guide to ensure complete resection of impinging osteophytes., (Copyright © 2013 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.)

Background: Controversy exists regarding the optimal technique of subscapularis mobilization during shoulder arthroplasty. The purpose of this study was to compare healing rates and subscapularis fatty infiltration in patients undergoing a lesser tuberosity osteotomy (LTO) versus subscapularis peel for exposure during shoulder arthroplasty., Materials and Methods: Eighty-seven patients, with a mean age of 67.8 ± 10.9 years, undergoing shoulder arthroplasty, were randomized to receive either an LTO (n = 43) or peel (n = 44). Computed tomography scans were conducted preoperatively and at 12 months postoperatively. Outcome variables included healing rates and subscapularis Goutallier fatty infiltration grade, as well as subscapularis strength and Western Ontario Osteoarthritis of the Shoulder Index and American Shoulder and Elbow Surgeons outcome scores., Results: Computed tomography imaging was available in 91% (n = 79) of the cohort. The healing rates for the peel (100%) and for the LTO (95%) did not differ significantly (P = .493). Preoperatively, the mean fatty infiltration grade for the peel (mean, 0.53) was not significantly different (P = .925) from the LTO (mean, 0.54). Postoperatively, the Goutallier mean fatty infiltration grade for the peel (mean, 0.95) did not differ significantly (P = .803) from the LTO (mean, 0.9). A significant increase in subscapularis fatty infiltration grade occurred postoperatively from the preoperative status (peel, P = .003; LTO, P = .0002). No statistically significant associations were observed between postoperative fatty infiltration grades and subscapularis strength, Western Ontario Osteoarthritis of the Shoulder Index scores, or American Shoulder and Elbow Surgeons scores., Discussion: No statistically significant differences were observed in the healing rates or subscapularis fatty infiltration grades between the peel and the LTO. This trial does not show any clear difference in radiologic and clinical outcomes of one subscapularis management technique over the other., (Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)

Background: Controversy exists regarding the optimal technique of subscapularis tendon mobilization during shoulder arthroplasty. The purpose of the present randomized double-blind study was to compare two of these techniques-lesser tuberosity osteotomy and subscapularis peel-with regard to muscle strength and functional outcomes., Methods: Patients undergoing shoulder arthroplasty were randomized to undergo either a lesser tuberosity osteotomy or a subscapularis peel. The primary outcome was subscapularis muscle strength as measured with an electronic handheld dynamometer at twenty-four months postoperatively. Secondary outcomes included the Western Ontario Osteoarthritis of the Shoulder Index and American Shoulder and Elbow Surgeons scores. A sample size calculation determined that eighty-six patients provided 90% power with a 0.79 effect size to detect a significant difference between groups., Results: Forty-three patients were allocated to subscapularis osteotomy, and forty-four patients were allocated to subscapularis peel. Eighty-three percent of the study cohort returned for the twenty-four-month follow-up. The primary outcome of subscapularis muscle strength at twenty-four months revealed no significant difference (p = 0.131) between the lesser tuberosity osteotomy group (mean [and standard deviation], 4.4 ± 2.9 kg) and the subscapularis peel group (mean, 5.5 ± 2.6 kg). Comparison of secondary outcomes, including the Western Ontario Osteoarthritis of the Shoulder Index and American Shoulder and Elbow Surgeons scores, demonstrated no significant differences between groups at any time point. Compared with baseline measures, mean subscapularis muscle strength, Western Ontario Osteoarthritis of the Shoulder Index score, and American Shoulder and Elbow Surgeons score all improved significantly in both groups at twenty-four months (p < 0.001)., Discussion: No significant differences in the primary or secondary outcomes of function were identified between the lesser tuberosity osteotomy group and the subscapularis peel group. For the parameters investigated, this trial does not demonstrate any clear advantage of one subscapularis treatment technique over the other.

Correct identification of the center point of the glenoid surface guides glenoid component placement. It is unknown whether the center point on the glenoid surface corresponds to the center of the glenoid vault at the medial extent of the glenoid prosthesis. We reviewed 20 consecutive computed tomography scans obtained preoperatively in patients with primary osteoarthritis. A glenoid center point was chosen on the glenoid surface and then projected back into the glenoid vault along the scapular axis and perpendicular to glenoid inclination. The difference from the projection of the glenoid surface center point to the center point at a 1.5-cm depth into the glenoid vault was then measured. The mean deviation of the glenoid center point at a depth of 1.5 cm from the center point at the glenoid articular surface was 1.7 mm anterior and 3.9 mm inferior. The most common deviation of the center point of the glenoid vault at the projected medial limit of the glenoid prosthesis was slightly anterior and inferior to the center point on the glenoid surface. Identifying the center of the glenoid surface coupled with alignment of the glenoid prosthesis in neutral version and anatomic inclination provides a reliable means to guide placement of glenoid components.

Background: Humeral head replacement has been used successfully for the treatment of osteoarthritis of the shoulder for decades. The purpose of this study was to define the results of this form of treatment, the risk factors for an unsatisfactory outcome, and the rates of failure over time., Methods: Between 1978 and 1997, sixty humeral head replacements were performed at our institution for the treatment of osteoarthritis. Five patients (seven shoulders) died less than five years postoperatively, and one patient (two shoulders) was lost to follow-up. Fifty-one humeral head replacements in forty-nine patients with a complete postoperative evaluation and operative records who had been followed for a minimum of five years (mean, 11.3 years) or until revision were included in the study. All sixty shoulders were included in the survival analysis., Results: Overall, there was significant long-term pain relief (p<0.0001) as well as improvement in active abduction (p<0.0001), internal rotation (p<0.024), and external rotation (p<0.0001) following the humeral head replacement. However, moderate pain was reported in nine shoulders and severe pain, in seven. Ten of the fifty-one shoulders underwent revision surgery, which was done to treat painful glenoid arthrosis in nine of the ten. Radiographs were available for thirty-nine shoulders, and they demonstrated an increase in glenoid erosion at a mean of 10.7 years postoperatively (p<0.0001). Five shoulders had humeral periprosthetic lucent lines of 1.5 mm in thickness, and three of them had a complete line; one humeral component had shifted in position. According to a modification of the Neer result rating system, there were ten excellent results, twenty satisfactory results, and twenty-one unsatisfactory results., Conclusions: Substantial clinical improvement can occur after humeral head replacement for osteoarthritis of the shoulder, but there is a high rate of unsatisfactory results and revision surgery. The decision as to whether this is the optimal surgical procedure for the treatment of osteoarthritis of the shoulder requires careful consideration.

Purpose: The purpose of this study is to report the early results with the Orthosphere (Wright Medical Technology Inc, Arlington, TN) spheric interpositional arthroplasty., Methods: Six women and 1 man had Orthosphere arthroplasty between 2000 and 2001. The mean age at the time of surgery was 52 years (range, 24-73 years) and the mean duration of clinical and radiographic follow-up evaluation was 33 months (range, 29-44 months)., Results: Six of 7 Orthosphere implants subsided into the trapezium resulting in pain, weakness, and stiffness. There was 1 implant dislocation. Five patients have had revision surgery to trapezial excision ligament reconstruction and tendon interposition arthroplasty. Of the remaining 2 patients 1 is contemplating presently revision surgery and the other is experiencing mild residual pain. No patients were satisfied completely with their Orthosphere results., Conclusions: In our experience the early outcome of the Orthosphere interpositional arthroplasty has been unacceptable. We no longer use the device at our institutions.