Assessing the validity of the distalization and lateralization shoulder angles following reverse total shoulder arthroplasty

BackgroundThe distalization shoulder angles (DSA) and lateralization shoulder angles (LSA) were developed to reproducibly measure DSA and LSA after reverse total shoulder arthroplasty (RSA). In this study, we sought to validate these measurements and their associations with clinical outcomes following RSA.MethodsWe retrospectively reviewed 238 patients undergoing RSA between May 2016 and December 2017 by 1 single-fellowship trained surgeon (A.J.). Two raters (K.A.M and E.C.) independently measured DSA and LSA in preoperative and postoperative radiographs (AP/Grashey and humeral-length views) using DSA, LSA, and humeral lengthening methodologies. DSA and LSA were then compared to patient-reported outcomes and range of motion (ROM) collected at 2-year follow-up.ResultsInterobserver reliability analysis showed near perfect agreement for DSA, LSA, and humeral lengthening. Lateralized prostheses were associated with higher LSAs (88.26 ± 7.44 vs. 81.95 ± 6.49; P < .001) when compared to medialized prostheses. DSA and humeral lengthening measurements did not correlate (R = 0.02; P = .88). LSA weakly correlated with 2-year postoperative American Shoulder and Elbow Surgeons score (R = 0.17, P < .05), but did not correlate with visual analog scale pain score or ROM. DSA did not correlate with patient-reported outcomes or ROM.ConclusionThe DSA and LSA shoulder angles are simple and highly reproducible measures, but seem to have marginal correlation with postoperative clinical outcomes. Further investigations into the prognostic utility of minimally cumbersome RSA measurement methodologies are warranted.Level of EvidenceLevel Ⅲ; Retrospective Cohort Study     

Humeral position after reverse shoulder arthroplasty as measured by lateralization and distalization angles and association with acromial stress fracture; a case-control study

BackgroundReverse Shoulder Arthroplasty (RSA) has become increasingly utilized in the surgical management for a growing number of indications in increasingly younger and active populations. The complication of Acromial Stress Fracture (ASF) has been described in various patient groups after RSA. Patients who experience ASF after RSA report worse clinical outcomes. Biomechanical studies and some clinical studies have implicated the degree of lateralization and distalization of the humerus as factors associated with development of ASF. Most prior studies utilize scalar or linear methods to measure humeral position following RSA. These scalar measurements do not account for the relative effects of variances in patient stature. Lateralization Shoulder Angle (LSA) and Distalization Shoulder Angle (DSA) are angular methods that have been described as a reproducible assessment of humeral position while controlling for variance in patient stature.MethodsA case-control study was performed where cases of ASF after RSA were identified after a retrospective review of all reverse shoulder arthroplasty cases at a single institution using a single implant type. A 1:3 case-control matching scheme was implemented based on age and gender. All surgeries were performed by one of 4 fellowship-trained Shoulder and Elbow surgeons. Preoperative and Postoperative radiographs were assessed and humeral position was measured using LSA and DSA. A Mixed Linear model was utilized to test the difference in means between cases and controls.ResultsBetween January 2012 and December 2015, 689 patients underwent primary RSA. 29 patients (4.2%) sustained acromial stress fracture. Acromial stress fracture occurred at a mean of 7.6 months after surgery (range 1.0-36.8 months). According to the Levy classification, 19 were type 1 fractures, 9 were type 2 and 1 was type 3. An additional 24 patients (3.5%) patients were noted to have experience an acromial stress reaction without evidence for fracture. Mean change in LSA (from preoperative to postoperative) was -19.78 ^o (SE 2.82) in cases (net medialization) and -12.18 ^o (SE 1.63) in controls (P= .02). The mean change in DSA was 36.40 ^o (SE 2.09) in cases and 31.82° (SE 1.21) in controls (P= .06)ConclusionHigher preoperative LSA (humeral lateralization) and greater decrease of LSA (greater net medialization) after surgery were noted to have an association with ASF. Humeral position after RSA as measured by DSA was not associated with radiographically evident ASF in this case-control study controlling for age and gender.Level of EvidenceLevel III, Case-control Prognosis Study     

Long-term relation between deltoid muscle volume and clinical outcomes in a reverse shoulder arthroplasty

BackgroundDeltoid muscle function is important in reverse shoulder arthroplasty (RSA). Concerns are raised on the resistance of the deltoid muscle against the postoperative distalization. We hypothesize that a decreased volume of the deltoid muscle is related to worse clinical outcomes after a long-term follow-up. An observational study was conducted to evaluate the relation between volume of the deltoid muscle and clinical outcomes after a long-term follow-up on RSA.MethodsEligible for inclusion was patients who underwent RSA for cuff arthropathy after minimum 3 years follow-up. Fifty-nine patients were enrolled in this study. Preoperative volume was measured on magnetic resonance imaging or computed tomography. Postoperative deltoid volume was evaluated on ultrasonography. Distalization of the humerus was measured on radiographs. Clinical outcomes were measured by the Constant-Murley Score (CMS), Oxford Shoulder Score, and range of motion. Multivariable linear regression models were used to examine the association between the deltoid volume and clinical outcomes, and between distalization and deltoid volume or clinical outcomes.ResultsThe mean follow-up period was 88.7 ± 29.1 months. Postoperative deltoid volume positively correlated with both CMS (P = .045) and abduction strength, in both operated (P = .01) and contralateral side (P < .001). No association between deltoid volume and Oxford Shoulder Score or range of motion, and no association between preoperative volume and postoperative CMS was found. The mean distalization of the humerus was 21.2 mm [95% CI: 19.4-22.9 mm]. Distalization negatively correlated with deltoid volume (P = .012) and CMS (P = .009).ConclusionsPostoperative deltoid volume correlated with clinical outcomes as measured by CMS and abduction strength after a long-term follow-up on RSA.     

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     

Function after closed reduction from early unstable reverse shoulder arthroplasty

BackgroundOptimizing deltoid tension during reverse shoulder arthroplasty (RSA) remains a challenge for the shoulder surgeon. Ideal tension likely differs based on patient age, anatomy, size, preoperative diagnosis, and deltoid strength. Excess tension might overstuff the joint and limit range of motion. The aim of this study was to compare the function of patients with early postoperative instability (as a proxy for deltoid tension) and those without instability.MethodsA retrospective cohort study comparing two groups of patients with primary RSA operated on over a 5-year period by a single fellowship-trained shoulder and elbow surgeon using a combination of lateralized and medialized glenoid prosthesis with a 135-degree neck-shaft angle on the humeral side was conducted. The main exposure was shoulder dislocation that did not require revision arthroplasty compared with all other patients in the study period who underwent uneventful primary RSA. Chart review was performed for patient demographics, preoperative diagnosis, operative details, preoperative and postoperative range of motion and pain, reoperation, and instability events. The primary outcome was final clinic visit forward elevation. Outcomes included preoperative, postoperative, and difference in forward elevation and external rotation, as well as pain level.ResultsA total of 79 shoulders treated with primary RSA from 2015 to 2019 were identified. The average follow-up was 9 months (range, 3-47 months). Sixty-seven patients (72 shoulders) underwent uneventful primary RSA. Seven patients (7 shoulders) in the treatment cohort presented to a postoperative visit with complaint of shoulder dislocation that was able to be self-reduced and/or presented with a dislocated shoulder requiring closed reduction without sedation. At the final follow-up, average postoperative forward elevation was 121 ± 27 degrees in stable shoulders versus 145 ± 15 degrees in the unstable group (P = .003). No significant difference in external rotation was shown between stable and unstable RSA (39 ± 12 degrees and 36 ± 14 degrees, respectively). Overall average forward elevation and external rotation improved from 71 to 123 degrees and 19 to 39 degrees, respectively. More than 95% of patients (69/72 uneventful RSA and 6/7 unstable RSA) reported improvement in shoulder pain postoperatively.ConclusionIn the absence of other reasons for instability, early dislocation after RSA is a potential marker of relatively loose deltoid tension. In this study, patients with instability demonstrated higher forward elevation. Patients without instability are likely a mix of those with optimal and suboptimal deltoid tension.Level of evidenceLevel III, Retrospective Comparative Treatment Study     

Return to golf after shoulder arthroplasty: golf performance and outcome scores

BackgroundGolf is an increasingly popular sport in the United States, especially among the age group of patients undergoing joint replacement. Return to golf after hip and knee arthroplasty has been previously studied. However, the quality and level of play after total shoulder arthroplasty (TSA) are less defined, especially after reverse shoulder arthroplasty (RSA). We hypothesize that shoulder pain and performance will improve during golf similarly after both anatomic and reverse total shoulder arthroplasties.MethodsThis is a retrospective cohort study of 69 patients identified as playing golf recreationally before undergoing either anatomic or RSA. All patients were cleared to return to golf activities 3 months after surgery. A golf-specific questionnaire was emailed to patients focusing on their experience returning to golf after shoulder arthroplasty. Results after TSA were compared with RSA. Patient-reported and functional outcome scores were evaluated.ResultsThe median age at surgery was 70 (62-73) years with 47 (68.1%) total shoulder replacements and 22 (31.9%) reverse shoulder replacements. Thirty-six (52.1%) patients returned to playing golf within 6 months and sixty (87.0%) patients returned to playing golf within 12 months after surgery. Enjoyment of golf either improved or stayed the same in 51 patients (91.0%). There was no significant change in the handicap score after shoulder replacement. Pain experienced during golf improved significantly from a median visual analog score pain of 6 to 1 (P < .001), with slightly greater improvement in pain for patients who underwent TSA (P = .025). Driving distance improved for 52.2% of patients, with patients who underwent TSA reporting significantly greater improvements in distance (P = .014). For all other questions, patients treated with anatomic shoulder arthroplasty and RSA reported similar experiences. American Shoulder and Elbow Surgeons score, Simple Shoulder Test score, Single Assessment Numerical Evaluation score, visual analog score function, active flexion, and external rotation all significantly improved at the most recent follow-up (P < .001).ConclusionReturn to golf after both reverse and anatomic total shoulder arthroplasties is a realistic expectation, with significant improvements in pain and function while playing golf. Enjoyment playing golf, golf performance, and average length of drive improve in approximately half of all patients. Patients treated with anatomic shoulder arthroplasty and RSA can expect similar golf experiences after surgery, with patients who underwent TSA experiencing a better improvement in driving distance.     

The biomechanics of subscapularis repair in reverse shoulder arthroplasty: The effect of lateralization and insertion site

Functional outcomes of subscapularis (SSc) repair following reverse shoulder arthroplasty (RSA) remains controversial. SSc repair in combination with glenosphere lateralization was reported to yield worse clinical outcomes compared with the non-lateralized glenosphere. The aim of this biomechanical study was to investigate how glenosphere lateralization and different re-insertion sites can affect the biomechanics of the SSc after RSA. Nine patient-specific RSA shoulder models were created from patients' computed tomography scans. Moment arms and SSc length were calculated for abduction, forward flexion, and internal rotation in 20° and 90° abduction for three configurations of glenosphere lateralization (standard/+0, +5, and +10 mm) and three SSc repair sites (native, superior, and inferior) and compared with the native shoulder. When compared with the native shoulder, RSA resulted in large adducting SSc moment arms that were antagonistic to the deltoid. Glenosphere lateralization had no effect on SSc moment arms in any motion. However, lateralization increased SSc tension beyond its anatomic length for +5 and +10 mm of lateralization when attached to its native insertion. A superior SSc repair site created the least adductive moment arm as well as the least amount of SSc lengthening. Increased glenosphere lateralization showed a significant increase in the SSc length, which in combination with its adductive moment arm can be antagonistic to deltoid function. However, a superior SSc repair site may help reduce the adductive SSc moment arm and allow for reduced tension on the repair as its length in that location is less than that of the native SSc. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:888-894, 2020     

Muscle and Joint Function After Anatomic and Reverse Total Shoulder Arthroplasty Using a Modular Shoulder Prosthesis

Changes in joint architecture and muscle loading resulting from total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (RSA) are known to influence joint stability and prosthesis survivorship. This study aimed to measure changes in muscle moment arms, muscle lines of action, as well as muscle and joint loading following TSA and RSA using a metal‐backed uncemented modular shoulder prosthesis. Eight cadaveric upper extremities were assessed using a customized testing rig. Abduction, flexion, and axial rotation muscle moment arms were quantified using the tendon‐excursion method, and muscle line‐of‐force directions evaluated radiographically pre‐operatively, and after TSA and revision RSA. Specimen‐specific musculoskeletal models were used to estimate muscle and joint loading pre‐ and post‐operatively. TSA lateralized the glenohumeral joint center by 4.3 ± 3.2 mm, resulting in small but significant increases in middle deltoid force (2.0%BW) and joint compression during flexion (2.1%BW) (p < 0.05). Revision RSA significantly increased the moment arms of the major abductors, flexors, adductors, and extensors, and reduced their peak forces (p < 0.05). The superior inclination of the deltoid significantly increased while the inferior inclination of the rotator cuff muscles decreased (p < 0.05). TSA using an uncemented metal‐backed modular shoulder prosthesis effectively restores native joint function; however, lateralization of the glenoid component should be minimized intra‐operatively to mitigate increased glenohumeral joint loading and polyethylene liner contact stresses. Revision RSA reduces muscle forces required during shoulder function but produces greater superior joint shear force and less joint compression. The findings may help to guide component selection and placement to mitigate joint instability after arthroplasty. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1988–2003, 2019     

Clinical and radiographic factors associated with internal rotation outcomes following reverse shoulder arthroplasty using an inlay stem design

BackgroundThe purpose of this study was to evaluate the relationship between preoperative subscapularis (SSc) status as well as radiographic factors with internal rotation (IR) following reverse shoulder arthroplasty (RSA). Our hypothesis was that increased glenosphere lateralization and SSc insertion lateralization and the absence of a preoperative SSc tear would be associated with improved postoperative IR (IR_F).MethodsA retrospective review was performed of primary RSAs (n = 132) by a single surgeon using a 135° inlay prosthesis. Range of motion including forward flexion (FF_F), external rotation (ER_F) and IR_F were evaluated at one year postoperative. IR_F was divided into high (≥L4) and low (≤L4) groups. Preoperative SSc status, glenosphere size, and postoperative positions of the glenosphere and humerus were assessed. Novel radiographic factors were used to assess lateralization including the lesser tuberosity scapula (LTS) and lateral glenosphere scapula (LGS) ratios.ResultsOnly 32% of patients achieved IR_F ≥ L4 postoperatively. Patients who achieved high IR_F had a lower incidence of preoperative SSc tear compared to those who had an IR_F < L4 (9% vs. 47%; P = .002). Higher LTS and LGS ratios were associated with improved IR_F (P < .001). The chance of having IR_F ≥ L4 increased by 86% (P = .049) and by 62% (P = .038) for every 0.1 increase in LGS ratio and LTS ratios, respectively.ConclusionWith a 135° inlay prosthesis design, an intact SSc preoperatively, as well as increased lateralization parameters, LTS and LGS ratios are associated with increased postoperative IR following RSA.Level of EvidenceLevel III; Retrospective Case-control Comparative Study     

Utilization of reverse shoulder arthroplasty for the treatment of glenohumeral arthritis among American Board of Orthopaedic Surgery (ABOS) Part II candidates, 2008-2019

BackgroundDespite advances in shoulder arthroplasty, treatment options for advanced glenohumeral osteoarthritis (GHOA) remain limited. Surgical management includes total shoulder arthroplasty (TSA), reverse total shoulder arthroplasty (RSA), and hemiarthroplasty. The rates of TSA and RSA for the treatment of GHOA in the United States has increased in recent years. Trends in shoulder arthroplasty in recently trained surgeons have not been explored. The purpose of the study was to examine the trends in arthroplasty use (TSA, RSA, and hemiarthroplasty) for primary GHOA among American Board of Orthopedic Surgeons (ABOS) Part II examinees, and to identify patterns based on geographic region or fellowship training.MethodsABOS Part II examinees with at least 1 shoulder arthroplasty in the examination years 2008-2019 were collected. Hemiarthroplasty, TSA, and RSA performed from 2007-2018 for a diagnosis of primary GHOA were included. Arthroplasty for primary or secondary diagnoses of fracture, infection, tumor, rotator cuff arthropathy or tear, revision, and non-arthroplasty procedures were excluded. Proportion and volume of cases were evaluated, with sub-analyses of geographic region and fellowship training. Univariate logistic regression determined statistical significance (P< .05).ResultsA total of 946,946 cases from 8609 ABOS Part II examinees were submitted, with 8733 shoulder arthroplasties performed. Overall, 3923 arthroplasties for primary GHOA were included (44.9% of all shoulder arthroplasties). TSA was used in 50.9% of cases. The proportion of RSA performed for primary GHOA has increased over the past 11 years, with RSA surpassing TSA as the most common procedure for primary GHOA over the last 4 years (P< .001). Hemiarthroplasty is less commonly. TSA and RSA were performed in similar proportions across regions, with the largest volume in the Midwest. Most procedures (91.5%) were completed by surgeons in sports medicine, shoulder and elbow, and those completing multiple fellowships. From 2008-2019 the number of RSA procedures performed for primary GHOA by sports medicine and shoulder and elbow surgeons has increased approximately 1100% and 800%, respectively (P< .001).ConclusionUtilization of RSA for treatment of primary GHOA by ABOS Part II examinees has increased significantly over the past twelve years. Among ABOS Part II examinees, RSA has recently surpassed TSA as the most common arthroplasty utilized for treatment of primary GHOA. Examination of early-career surgical practice allows for consideration of training influence in treatment of GHOA. As volume of shoulder arthroplasty continues to increase, trends and procedure volume have implications for clinical practice and patient outcomes.Level of EvidenceLevel IV; Case-series Database Study     

Does acromion anatomy affect the risk of acromion stress fracture after reverse shoulder arthroplasty?

IntroductionReverse shoulder arthroplasty (RSA) alters normal anatomic relationships and results in increased deltoid forces. Which alter physiologic stress patterns in the acromion resulting in fractures. The purpose of this study was to evaluate the effect of acromion anatomy on the stress levels and risk of acromial fracture after RSA.MethodsA lateralization onlay design of the Exactech Equinoxe RSA standard stem was used for all four different acromial sizes (ranging from −5.0 mm to +5.0 mm) and compared to standard normal shoulder model (acromial size 0). A finite element analysis (FEA) model was then constructed for each case and quasi-static analysis was carried out to determine the highest minimum principal stress (HMPS) for each case and this was used to predict fatigue life percentage (FLP) of the acromion.ResultsFor smaller acromion sizes of −5 mm and -2.5 mm, the HMPS was found to be 1.87 and 1.24 times higher than the standard, respectively. The HMPS for the +2.5 mm acromial size was 0.95 times compared to the standard and 1.04 times higher for the +5 mm acromial size. According to our model, the highest FLP was seen when the acromion size was +2.5 mm (case 4 - 178%) and the lowest FLP was seen when it was -5 mm (−0.06%).ConclusionOur results suggest that there is an optimal acromion size (+2.5 mm from normal male) that leads to the lowest fracture risk in RSA. Surgeons must be aware of acromion size as a critical factor in deltoid tensioning, acromial stress, and risk of acromial fracture when selecting optimal implant designs and sizes for RSA.Level of evidence: Basic Science Study     

Biomechanical analysis of the subscapularis,infraspinatus and teres minor length and moment arm after reverse shoulder arthroplasty: a cadaveric study

BackgroundReverse shoulder arthroplasty (RSA) affects the length and moment arm of the deltoid and rotator cuff. Currently, RSA is commonly considered for cuff-intact conditions, such as primary glenohumeral osteoarthritis. As such, understanding the effect of contemporary lateralized designs on the rotator cuff is paramount. The purpose of this study was to determine changes in length and moment arm of the subscapularis, infraspinatus and teres minor with implantation of one of 3 RSA designs.MethodsA previously validated model was used in 6 hemi-toraces with the shoulder attached. Suture lines were run through pneumatic cylinders from the insertion to the origin of 10 muscles to apply a constant, stabilizing load. Electromagnetic tracking sensors were fixed to the thorax, scapula, and humerus to record 3-dimensional kinematics. Coordinate systems were established according to ISB recommendations. The origin and insertion of the subscapularis, infraspinatus and teres minor were digitized and tracked. Testing consisted of manually rotating the humerus through 5 cycles of its internal-external rotation arc. Kinematic data was collected at 120 Hz. Testing was performed in 3 positions of abduction: 0°, 30°, and 60°. After testing the intact shoulder, RSA was performed using 3 different configurations: an onlay 135-degree humeral component matched with a 2-mm lateralized glenosphere, the same humeral component with a 6-mm lateralized glenosphere, and an inlay 135-degree humeral component matched with a 10 mm lateralized glenosphere. Minimal muscle operative lengths, maximal muscle operative lengths, and muscle moment arms were computed.ResultsWhen compared with the native shoulder, all 3 configurations of RSA resulted in statistically significant increases in both the minimal and maximal operative lengths of the subscapularis in all abduction positions. The teres minor only showed a statistically significant increase in minimal and maximal length at 60° of abduction. The infraspinatus showed a statistically significant increase in tendon excursion at 0° and 30° of abduction. In 40° of abduction and 40° of internal rotation, all RSA configurations translated in a decreased subscapularis internal rotation moment arm. On the contrary, RSA increased the external rotation moment arm of the infraspinatus in neutral rotation and 0° of abduction.ConclusionImplantation of contemporary lateralized RSA implants led to increased length of the subscapularis to a greater extent than the increased length experienced by the infraspinatus and teres minor. The moment arm of the subscapularis decreased, whereas the moment arm of the teres minor in neutral rotation with the arm in abduction increased.Level of EvidenceLevel III; Basic Science, Biomechanics Study     

Revision of failed reverse shoulder arthroplasty to revision reverse shoulder arthroplasty leads to significant clinical and functional improvement

BackgroundReverse shoulder arthroplasty (RSA) is rapidly growing in the United States. As the number of procedures increases, the number of complications and need for additional surgeries correspondingly continues to grow. The purpose of this study was to describe clinical and functional outcomes of revision of RSA to RSA.MethodsA retrospective review of 29 patients from 2 centers who underwent revision surgery following RSA to RSA from 2007 to 2017 was conducted. The reasons for revision were recorded. Clinical outcome measures including shoulder range of motion, American Shoulder and Elbow Surgeons score, Single Assessment Numerical Evaluation score, simple shoulder test and Visual analog scale scores were collected for all patients at an average follow-up of 29 months. Postoperative complications were also recorded.ResultsA total of 29 patients were identified. The average time between index RSA and revision was 2.3 years (30 days – 7 years). Mean follow-up duration for clinical outcome measures was 29.1 months (12-114 months). The most common indication for revision surgery was aseptic loosening (13/29, 44.8%), followed by instability (7/29, 24.1%), fracture (5/29, 17.2%), and infection (4/29, 13.7%). The average Visual analog scale decreased from 7 to 3 (P< .001). American Shoulder and Elbow Surgeons score scores improved from a mean of 30 to 58 (P < .001). Single Assessment Numerical Evaluation score scores improved from 26 to 54 (P < .001), and Simple shoulder test improved from 2 to 6 (P = .001). Range of motion in both forward elevation from 76° to 131° (P < .001) and external rotation from 26 to 42 (P = .001). Complications were seen in 10 of 29 patients (34.5%).ConclusionA failed RSA can be managed with revision RSA with acceptable clinical outcomes although outcome is inferior to primary RSA with a high rate of complications.Level of EvidenceLevel IV; Retrospective Case Series     

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.     

Clinical application of intraoperative O-arm navigation in reverse shoulder arthroplasty

BackgroundInaccurate fixation and positioning of the glenoid component using conventional techniques are problematic in reversed shoulder arthroplasty (RSA). Our objective was to investigate the accuracy of O-arm navigation of the glenoid component in RSA.MethodsThis retrospective case–control study comprised 2 groups of 25 patients who underwent reversed shoulder arthroplasty with or without intraoperative O-arm navigation. The intraoperative goal was to place the component neutrally in the glenoid in the axial plane and 10° inferiorly tilted in the scapular plane. Glenoid version angle and inclination were measured by computed tomography obtained preoperatively and a year postoperatively. Operative time, intraoperative bleeding, and the presence of postoperative complications were recorded.ResultsCompared with the ideal, the range of error for version was 7.3° (SD 3.6°) in the control group and 5.6° (SD 3.6°) in the navigated group (P = 0.278), and the range of error for inclination was 18.3° (SD 11.7°) in the control group and 4.9° (SD 3.8°) in the navigated group (P = 0.0004). The mean operative time was 164.6 (SD 21.2) min in the control group and 192.0 (SD 16.2) min in the navigated group (P = 0.001). The mean intraoperative bleeding was 201.0 (SD 37.0) mL in the control group and 185.3 (SD 35.6) mL in the navigated group (P = 0.300). There were no complications reported related to the intraoperative O-arm navigation.ConclusionO-arm navigation may be a useful tool for the placement with inferior tilt of the glenoid procedure in reversed shoulder arthroplasty.     

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     

Shoulder arthroplasty in patients with ipsilateral hemiparesis: a safe and durable procedure? A case series

HypothesisShoulder arthroplasty is a safe and durable procedure that provides pain relief, improved range of motion (ROM), and minimal complications for shoulder pain and dysfunction in patients with ipsilateral hemiparesis.MethodsThis is a retrospective review of all adult patients who underwent primary reverse total shoulder arthroplasty (RSA) or total shoulder arthroplasty (TSA) in the hemiparetic upper extremity at a single quaternary care academic medical center from 1988 to 2019. Patients were excluded if their neurologic insult was secondary to a spinal-cord injury, cerebral palsy, or inflammatory arthritis, if they underwent a hemiarthroplasty, if they exhibited mild hemiparesis (Medical Research Council Scale of ≥4), or if they had less than 30 days of radiographic follow-up. The primary clinical outcome was revision surgery for any reason. The secondary clinical outcomes included pain using the visual analog scale, ROM via active-assisted manual muscle testing (AAROM), and postoperative complications. The primary radiographic outcome was implant lucency using a standard scale.ResultsA total of 5 shoulders in 5 patients were included, 4 RSAs and 1 TSA with a mean clinical follow-up of 6.2 years (range: 1.42-14.2 years) and mean radiographic follow-up of 3.7 years (range: 31 days-13.5 years). No patient underwent revision surgery. The mean visual analog scale score significantly improved from 7.6 to 1.4 at the last follow-up (P = .005). The mean forward elevation AAROM improved from 27° preoperatively to 88° at the last follow-up (P = .015). There was no significant difference in external rotation at the last follow-up (P = .105). One patient had asymptomatic grade 1 glenoid component lucency with superior subluxation of the humerus after undergoing TSA at a final follow-up of 4.5 years. No other complications were reported.ConclusionShoulder arthroplasty is a durable procedure that provides pain relief, improved AAROM, and minimal complications in patients with ipsilateral hemiparesis. The increase in active-assisted forward elevation ROM can improve caregiver ease with hygiene and dressing. Patients in this study who underwent RSA did not have subsequent glenohumeral dislocation. Larger numbers of patients would be required for adequate power analysis regarding instability in this cohort of patients who may be at risk; our small series did not identify any instability events.Level of evidenceLevel IV; Treatment Study     

Use of preoperative advanced imaging for reverse total shoulder arthroplasty

BackgroundIn order to avoid implant related complications related to glenosphere malposition, there has been an increased interest in the use of advanced imaging, including computed tomography (CT) and magnetic resonance imaging (MRI) for preoperative planning and patient-specific instrumentation for reverse shoulder arthroplasty (RSA). While recent literature has demonstrated improved component position when this technology is applied, the clinical benefits remain largely hypothetical and unproven. Thus, the goals of the current study were to utilize a national database to describe current trends in the use of preoperative advanced imaging and investigate the relationship between such imaging and postoperative complications compared to matched controls without any preoperative imaging.MethodsPatients undergoing RSA for non-fracture indications were identified within the Mariner dataset within the PearlDiver database from 2010 to 2018Q2. Patients who underwent preoperative advanced imaging (MRI and/or CT) within a year prior to surgery were then identified as study cohorts. A matched cohort undergoing RSA without preoperative advanced imaging was created for comparison purposes. The incidence of imaging over time and rates of loosening/osteolysis, periprosthetic fracture, prosthetic dislocation, and revision shoulder arthroplasty of all groups were compared using a regression analysis.ResultsThe percentage of patients who underwent preoperative CT (141% increase, P < .0001), and either MRI or CT (107% increase, P = .002) increased significantly during the study period, while there was no significant increase in MRI utilization (P = .122). Patients who underwent preoperative CT experienced significantly lower rates of revision shoulder arthroplasty (2.4% vs. 3.3%, OR = 0.72, P = .004) and periprosthetic dislocation (2.8% vs. 3.3%, OR 0.80, P = .039) within 2 years of RSA compared to patients who did not undergo preoperative CT, while preoperative MRI was associated with significantly lower rates of periprosthetic fracture (0.2% vs. 0.4%, OR 0.44, P = .005), revision shoulder arthroplasty (2.1% vs. 2.6%, OR = 0.75, P = .006), and periprosthetic dislocation (2.5% vs. 3.2%, OR 0.78, P = .003) within 2 years of RSA compared to patients without an MRI.ConclusionThere has been a significant increase in the utilization of preoperative CT as compared to MRI for RSA during the time period studied. The utilization of preoperative advanced imaging may be associated with a statistically significant reduction in multiple implant related complications following RSA for non-fracture indications, although these findings are of unclear clinical significance given limitations of the database and low percentage difference in complication rates.Level of Evidence: Level III     

Clinical and radiographic predictors of difficult primary shoulder arthroplasty

BackgroundAnecdotally there is a spectrum of complexity in performing shoulder arthroplasty, however, there is limited information to predict easy versus difficult cases. The purpose of this study was to identify clinical and radiographic factors that are associated with difficult primary shoulder arthroplasty.MethodsAll consecutive primary shoulder arthroplasties performed by one-of-five high-volume shoulder and elbow fellowship-trained surgeons from 4/2018-8/2018 were included. Mean (range) surgeon years in practice was 19.4 (6-29). Surgeons completed a preoperative questionnaire estimating the level of complexity in performing the operation from very easy, easy, average, difficult, and very difficult. The same questionnaire was completed immediately postoperatively regarding level of complexity. Difficult group was defined if the surgeon rated as difficult or very difficult on the postoperative questionnaire. If the procedure was difficult, the postoperative questionnaire assessed what aspect of the procedure made it difficult. Demographics, clinical and radiographic factors, and procedure time were collected.ResultsDuring the study period, 224 primary shoulder arthroplasties were performed (53% reverse, 44% anatomic, 3% hemiarthroplasty with concentric glenoid reaming). Difficult group consisted of 95 shoulder arthroplasties (42.4%). Difficult group procedure time was a mean 21.8 minutes longer (120.7 ± 3.1 min vs. 98.9 ± 2.4 min; P <.001). Glenoid reaming and implantation (48.4%) were the most common reason for difficult cases, followed by glenoid exposure (33.7%). The surgeon correctly predicted level of complexity in 77% of cases (i.e., predicted difficult preoperatively and assigned difficulty postoperatively). There were 39 cases that were incorrectly predicted easy preoperatively and assigned as difficult postoperatively. Of all the cases predicted to be easy, those cases that were rated as difficult postoperatively were associated with younger age (67.1 ± 1.4 vs. 71.2 ± 0.7; P =.006), males (61.5% vs. 34.3%; P = .003), higher BMI (31.7 ± 0.9 vs. 29.6 ± 0.5; P = .045), history of instability (30.8% vs. 10.5%; P = .003), decreased passive external rotation (17.5 ± 3.1 vs. 25.1 ± 1.4, P = .031), larger inferior humeral head osteophyte (14.1mm vs. 7.8mm, P = .001) and B2 or B3 glenoids (39.3% vs. 17.2%; P =.026).Discussion and conclusionFor experienced high-volume shoulder and elbow surgeons performing primary shoulder arthroplasty, cases that were unexpectedly difficult were associated with younger age, males, stiffness, history of instability, large inferior humeral head osteophyte, and posterior glenoid bone loss. Difficulty with glenoid reaming and glenoid component implantation were the most frequent reason for difficult cases. This information may allow surgeons to anticipate difficult cases, appropriately schedule their operative day, and identify potentially difficult cases that warrant referral to high-volume shoulder arthroplasty surgeon.Level of evidenceLevel III; Prospective Case-Control Study