Impact of humeral component retroversion on clinical outcomes of reverse total shoulder arthroplasty with humeral lateralization

BackgroundThe effect of humeral component retroversion on clinical outcomes after reverse total shoulder arthroplasty (RTSA) is unclear. Intended retroversion intraoperatively may not produce the same retroversion of the humeral component postoperatively.MethodsThis retrospective study was conducted on consecutive patients who received RTSA using a single product with humeral lateralization at a targeted 25° of humeral retroversion from 2014 to 2019 with minimum 1-year clinical follow-up and postoperative computed tomography (CT). Forty-five patients were enrolled, and humeral component retroversion was measured three-dimensionally. Correlation and regression analyses were conducted between humeral retroversion and postoperative isometric strength and range of motion in forward flexion (FF), external rotation (ER), and internal rotation (IR). Group comparison between a ≤25° group and a >25° group was conducted as sub-analysis to verify possible confounders.ResultsThe actual humeral retroversion was 21.7 ± 11.9°, and it was significantly correlated with postoperative FF [Pearson's correlation coefficient (PCC) = 0.464, P= .003], ER (PCC = 0.481, P = .002), and IR (PCC = 0.471, P = .002) strengths. Multivariable regression analysis showed that humeral retroversion was significantly associated with postoperative FF (Exp(B) = 0.492, P = .003), ER (Exp(B) = 0.336, P = .002), and IR (Exp(B) = 0.578, P = .002) strengths. Two groups in sub-analysis showed no significant difference in pre- or intraoperative variables other than humeral component retroversion. Some functional outcome scores including the Constant score, American Shoulder and Elbow Surgeons score, and activity scales were significantly higher in the >25° group.ConclusionDiscrepancies between intraoperatively targeted humeral retroversion angle and actual postoperative angle after RTSA should be considered by operators and researchers. Increased humeral component retroversion than recommendation can yield acceptable outcomes and might be associated with higher postoperative strength, and possibly with better functional outcome after RTSA with humeral lateralization.Level of evidenceLevel III; Retrospective Comparative Study     

Analysis of impingement-free range of motion of the glenohumeral joint after reverse total shoulder arthroplasty using three different implant models

Background

This study aimed to investigate impingement-free range of motion (ROM) of the glenohumeral joint following reverse total shoulder arthroplasty (RTSA) with three types of implant models using computational motion analysis.

The glenohumeral micromotion and influence of the glenohumeral ligaments during axial rotation in varying abduction angle

BackgroundThe patients with shoulder instability or disorders in overhead athletes have been considered to have an abnormal micromotion at the glenohumeral joint. However, the normal range of the micromotion has not been available during axial rotation with various abduction angles, especially above 90° abduction. This study aimed to investigate the glenohumeral translation and influence of the glenohumeral ligaments during axial rotation with up to maximum abduction.MethodsFourteen healthy volunteers performed active axial rotations at 0°, 90°, 135°, and maximal abduction angles. The positions of the humeral head center relative to the glenoid at maximally external, neutral, and maximally internal rotations (ER, NR, IR, respectively) for each abduction angle were evaluated using two- (2D) and three-dimensional (3D) shape matching registration techniques. The shortest pathway and its length between the origin and insertion of the superior, middle, and inferior glenohumeral ligaments (SGHL, MGHL, and IGHL, respectively) were calculated for each position.ResultsThe glenohumeral joint showed 3.1 mm of superoinferior translation during axial rotation at 0° abduction (P < 0.0001), and 2.6 mm and 4.5 mm anteroposterior translation at 135° and maximal abduction (P < 0.0001), respectively. The SGHL and MGHL reached a maximum length at ER with 0° abduction, and the anterior and posterior bands of the IGHL reached a maximum at ER with 90° abduction and IR with 0° abduction.ConclusionsThese findings indicated that the SGHL played a role as an inferior suppressor at 0° abduction, while the anterior band of IGHL played a role as an anterior stabilizer at 90° abduction. Every glenohumeral ligament did not get taut and the anteroposterior translation became greater with increasing abduction angle, above 90°. These results could be used as a reference when comparing with the pathological shoulders in the future study.     

Does Humeral Component Lateralization in Reverse Shoulder Arthroplasty Affect Rotator Cuff Torque? Evaluation in a Cadaver Model

Background

Humeral component lateralization in reverse total shoulder arthroplasty (RTSA) may improve the biomechanical advantage of the rotator cuff, which could improve the torque generated by the rotator cuff and increase internal and external rotation of the shoulder.

Purpose

The purpose of this in vitro biomechanical study was to evaluate the effect of humeral component lateralization (or lateral offset) on the torque of the anterior and posterior rotator cuff.

Methods

Eight fresh-frozen cadaveric shoulders from eight separate donors (74 ± 8 years; six males, two females) were tested using an in vitro simulator. All shoulders were prescreened for soft tissue deficit and/or deformity before testing. A custom RTSA prosthesis was implanted that allowed five levels of humeral component lateralization (15, 20, 25, 30, 35 mm), which avoided restrictions imposed by commercially available designs. The torques exerted by the anterior and posterior rotator cuff were measured three times and then averaged for varying humeral lateralization, abduction angle (0°, 45°, 90°), and internal and external rotation (−60°, −30°, 0°, 30°, 60°). A three-way repeated measures ANOVA (abduction angle, humeral lateralization, internal rotation and external rotation angles) with a significance level of α = 0.05 was used for statistical analysis.

Results

Humeral lateralization only affected posterior rotator cuff torque at 0° abduction, where increasing humeral lateralization from 15 to 35 mm at 60° internal rotation decreased external rotation torque by 1.6 ± 0.4 Nm (95% CI, −0.07 −1.56 Nm; p = 0.06) from 4.0 ± 0.3 Nm to 2.4 ± 0.6 Nm, respectively, but at 60° external rotation increased external rotation torque by 2.2 ± 0.5 Nm (95% CI, −4.2 to −0.2 Nm; p = 0.029) from 6.2 ± 0.5 Nm to 8.3 ± 0.5 Nm, respectively. Anterior cuff torque was affected by humeral lateralization in more arm positions than the posterior cuff, where increasing humeral lateralization from 15 to 35 mm when at 60° internal rotation increased internal rotation torque at 0°, 45°, and 90° abduction by 3.2 ± 0.5 Nm (95% CI, 1.1–5.2 Nm; p = 0.004) from 6.6 ± 0.6 Nm to 9.7 ± 0.6 Nm, 4.0 ± 0.3 Nm (95% CI, 2.8-5.0 Nm; p < 0.001) from 1.7 ± 1.0 Nm to 5.6 ± 0.9 Nm, and 2.2 ± 0.2 Nm (95% CI, 1.4–2.9 Nm; p < 0.001) from 0.6 ± 0.6 Nm to 2.8 ± 0.6 Nm, respectively. In neutral internal and external rotation, increasing humeral lateral offset from 15 to 35 mm increased the internal rotation torque at 45˚ and 90˚ abduction by 1.5 ± 0.3 Nm (95% CI, 0.2–2.7 Nm; p = 0.02) and 1.3 ± 0.2 Nm (95% CI, 0.4–2.3 Nm; p < 0.001), respectively.

Conclusions

Humeral component lateralization improves rotator cuff torque.

Clinical Relevance

The results of this preliminary in vitro cadaveric study suggest that the lateral offset of the RTSA humeral component plays an important role in the torque generated by the anterior and posterior rotator cuff. However, further studies are needed before clinical application of these results. Increasing humeral offset may have adverse effects, such as the increased risk of implant modularity, increasing tension of the cuff and soft tissues, increased costs often associated with design modifications, and other possible as yet unforeseen negative consequences.

     

Comparison of two-dimensional manual and three-dimensional SurgiCase and BLUEPRINT planning software measurements of glenoid version,inclination, and humeral subluxation

IntroductionVirtual planning for shoulder arthroplasty using preoperative computed tomography (CT) has been gaining popularity, and it is imperative for surgeons to recognize any differences in measurements that may exist amongst software platforms. The purpose of this study is to compare measurements of glenoid version, inclination, and humeral head subluxation between a manual approach and two varying automated software platforms using either a best-fit sphere technique (Wright-Medical BLUEPRINT) or an anatomic landmarks technique (Materalise SurgiCase).MethodsA case control study of 289 CT images from patients preoperatively planned for a total shoulder arthroplasty or reverse shoulder arthroplasty using SurgiCase (v3.0.110.5) were also successfully analyzed by BLUEPRINT (v2.1.6). Glenoid version, inclination, and subluxation were measured manually in a blind fashion by two separate investigators using axial and coronal images oriented to the scapular plane; interobserver and intraobserver reliabilities were measured using intraclass correlation coefficients (ICCs). Concordance correlation coefficients (CCCs), mean differences, and clinically relevant agreement in measurements between the software platforms and with the manual technique were compared. The impact of greater glenoid retroversion on the differences in measurements between the software platforms was further studied by correlation analysis.ResultsThe mean differences between SurgiCase and BLUEPRINT were + 0.5° for glenoid inclination (P = .064; CCC = 0.84), -0.9° for glenoid version (P < .001; CCC = 0.92), and -1.4% for humeral subluxation (P = .002; CCC = 0.88). Agreement within 5 units was 78.9% for inclination, 89.3% for version, and 64.1% for subluxation. Glenoid retroversion had no relation with the degree of variation in measured inclination (P = .59) or version (P = .56). There were significant differences between manual and 3D software measurements for glenoid inclination, version, and subluxation (P < .001). Both software measurements were more inferiorly inclined (average difference, SurgiCase -3.2° and BLUEPRINT -3.9°), more retroverted (average difference, SurgiCase -4.0° and BLUEPRINT -3.2°), and more posteriorly subluxated (average difference, SurgiCase + 3.4% and BLUEPRINT + 4.8%).ConclusionThe SurgiCase and BLUEPRINT preoperative planning software yield clinically similar measurements for glenoid version, inclination, and subluxation. The degree of glenoid retroversion does not impact the variability of inclination or version between the landmark and best-fit sphere software techniques. Compared to the 2D manual technique, both 3D software programs reported greater inferior inclination, retroversion, and posterior subluxation.Level of evidenceLevel III; Retrospective Diagnostic Study     

Shoulder Position During Magnetic Resonance Arthrogram Significantly Affects Capsular Measurements

PurposeTo determine whether change in shoulder position between internal rotation (IR) and external rotation (ER) during magnetic resonance arthrography (MRA) affects previously defined capsular measurements and to determine the utility of rotation in the diagnosis of instability.MethodsA retrospective study was conducted of patients who received a shoulder MRA with humeral IR and ER views. Patients with an arthroscopically confirmed diagnosis of instability and those with clinically stable shoulders, no history of instability, and no MRA findings of instability were identified and compared. Humeral rotation, glenoid retroversion, humeral head subluxation, capsular length, and capsular area using axial sequences of IR and ER views were recorded. Analysis compared IR, ER, and Δ capsular measurements between groups using independent t tests and univariate and multivariate regression.ResultsThirty-one subjects who were diagnosed with instability were included, along with 28 control subjects. Capsular length, capsular area, and humeral subluxations were significantly greater with ER compared with IR views (P < .001, P < .001, P < .001). Patients with instability displayed greater ER capsular length (P = .0006) and ER capsular area (P = .005) relative to controls. Multivariate logistic regression identified age, weight, sex, ER capsular length, and retroversion to be significant predictors of instability. ER capsular length independently predicts instability with 86% sensitivity and 84% specificity. Interobserver reliability using the intraclass correlation coefficient was rated good or excellent on all measurements.ConclusionVariance in humeral rotation during shoulder MRA significantly affects capsular measurements. Rotational views increase the utility of capsular measurements when assessing for instability, particularly capsular length and capsular area. The implementation of ER positioning enhances the ability to examine capsular changes of the shoulder joint and can assist in the diagnosis of instability.Level of EvidenceIII, retrospective comparative study     

Defining deformity thresholds for the use of augmented glenoids in arthritic shoulders with posterior glenoid bone loss

BackgroundDespite increasing utilization, little guidance is offered regarding appropriate indications for posterior augmented glenoid implants. The purpose of this study is to virtually assess the effect of implant selection on glenoid resurfacing and joint line restoration in osteoarthritic shoulders with posterior glenoid wear.MethodsThirty-three CT scans were randomly selected from a cohort of osteoarthritic shoulders with Walch B2 or B3 deformities. Imascap SAS (Wright Medical, Memphis, TN) was used to assess bony deformities and plan glenoid resurfacing. Implants simulated included: standard Pegged Cortiloc, and 15° and 25° half-wedge augments. Each component was planned for a version correction to neutral and 10° retroversion, inclination was maintained within 5° of neutral and the component was medialized until bony support reached 80%. Implantation failure was defined as: greater than 20% cancellous bone support, central peg perforation, or joint line medialization relative to the pathologic joint (accounting for polyethylene thickness). Excessive lateralization was defined as creation of a joint-line >4 mm lateral to the pathologic joint-line.ResultsThe mean retroversion deformity in this cohort was 23.7° (range: 13°-37°). When correcting to neutral, the corrective reaming alone failed in 72.7% (24/33) of cases compared to 15.2% (5/33) when correcting to 10° of implant retroversion. When correcting to neutral version failure was decreased with a 15° (27.3%; 9/33; P < .001) and 25° augment (15.2%; 5/33; P < .001). Receiver operating characteristic (ROC) analysis found that an augment is useful to resolve standard implant failure for retroversion deformities greater than 27° (area under the curve [AUC] = 0.91) and 22° (AUC = 0.77) for correcting version to neutral and 10° retroversion, respectively. When placing a 25° augment, there was high risk of overstuffing the joint for both correction to neutral (27.3%) and 10° retroversion (66.7%). Overstuffing was likely to occur when correcting deformities less than 19° (AUC = 0.96) to neutral with a 25° augment. Likewise, implanting 15° or 25° augmented glenoids in 10° of retroversion is likely to overstuff the joint for pathologic retroversion deformities smaller than 18° (AUC = 0.94) and 28° (AUC = 0.69), respectively.ConclusionThis study helps to clarify the severity of glenoid deformities more appropriately addressed with the use of a half-wedged augmented glenoid. Both the severity of glenoid deformity and the desired implant version affect appropriate indications for the use of augmented glenoids. The risk of excessive joint-line lateralization in shoulders with less severe deformities should not be ignored. These considerations, in addition to individual soft tissue tension should be considered when planning and performing glenoid resurfacing.Level of evidenceLevel III; Treatment Study     

The Glenoid Vault Outer Cortex (GVOC) radiological reference for shoulder arthroplasty evaluated in aging scapulae

BackgroundAccurate glenoid component positioning is an important determinant of outcome in a shoulder arthroplasty surgery. Optimal glenoid placement is determined using bony landmarks of the scapula. The Glenoid Vault Outer Cortex (GVOC) has been recently described as a new, more accurate radiological reference. This has, however, only been evaluated against current standard references in young patients. Further investigation of the GVOC in older patients is therefore warranted. We, therefore, evaluated the effect of aging on the accuracy and stability of the GVOC, in determining glenoid anatomy as compared to the commonly used Scapular Border (SB) plane.MethodsComputed tomography imaging of 129 individual scapulae was obtained retrospectively from a cohort of patients who had undergone either total body or region-specific computed tomography imaging which included the shoulder region. This comprised of 35 males and 33 females (64 and 65 scapulae respectively) who were aged from 30 to 92 years. Imaging of 54 scapulae was from patients aged ≥60 years. The accuracy of the GVOC plane was then assessed against the SB plane.ResultsIn all patients, the mean difference between estimates using the GVOC plane and the GR (actual) was 2.2° (standard deviation [SD], 4.2) for version, and 1.8° (SD, 4.9) for inclination (P < .001). This contrasted with values of 7.6° (SD, 7.6) for version, and 22.9° (SD, 10.8) for inclination when using the SB reference plane (P < .001). Within the group aged ≥60 years, the mean difference between estimates using the GVOC plane and the glenoid rim (actual) was 3.2° (SD, 4.7) for version and 1.9° (SD, 3.1) for inclination, (P < .001). This contrasted to 10.0° (SD, 7.2) for version, and 23.4° (SD, 10.7) for inclination when using the SB plane (P < .001).Separately it was noted that the GVOC’s relationship to the glenoid rim remained constant throughout aging as opposed to the SB which changed significantly over time effecting estimates of glenoid retroversion.ConclusionsThe GVOC is a new plane of reference developed specifically for the use in shoulder arthroplasty. It is shown to be more accurate and stable in the aging scapulae than the currently used SB plane. The future development of guides and planning softwares that utilize the GVOC may provide an important opportunity for improved accuracy and outcome in shoulder arthroplasty.     

Reverse total shoulder arthroplasty with a custom deltoid lateralization sleeve for the treatment of failed arthroplasty and severe proximal humeral bone loss

IntroductionReverse total shoulder arthroplasty (RTSA) is reportedly an effective option in the treatment of glenohumeral arthritis and severe comminuted proximal humeral fractures. To date, RTSA failures and their subsequent revisions are significant issues that have not been well studied. In revision RTSA cases with severe proximal humeral bone loss (PHBL), there is increased risk of early failure [4,10,28,30]. In this series, the authors evaluate the short-term results of a novel custom-made, patient-specific Deltoid Lateralization Sleeve (DLS) with an adjustable humeral RTSA component for revision of failed arthroplasty with severe bone loss.MethodsPatients treated with a custom, adjustable DLS system for revision RTSA between 2012 and 2019 at one institution were identified using medical health records and included in the study. Each patient had undergone multiple previously failed surgeries before the current salvage procedure was performed. Revision RTSAs with less than 5 centimeters (cm) of bone loss, precluding DLS use, were excluded. Data was retrospectively collected and included demographics, surgical history, amount of bone loss in centimeters, preoperative and postoperative range of motion (ROM), patient-reported outcome scores, and postoperative complications.ResultsFrom 2012 to 2019, 15 patients with a mean PHBL of 8.3 cm (range 5-12.5 cm) underwent revision RTSA with DLS. Median age was 66.0 years (range 25-81 years). Median clinical and radiographic follow-up was 30 months (range: 23-77 months). Median preoperative active anterior elevation (AE), active external rotation, and active internal rotation improved from 10° to 120°, 0° to 35°, and 0° to 40°, respectively. Median Visual Analog Scale pain score improved from 5 to 0, American Shoulder and Elbow Surgeons score improved from 25 to 65, Simple Shoulder Test score improved from 0 to 46, and Single Assessment Numeric Evaluation (SANE) score improved from 20% to 68%. There were 9 (60%) complications, including 5 major complications requiring revision surgery (33.3%). One patient (6.7%) was lost to follow-up.Discussion/ConclusionRevision RTSA for excessive PHBL with severe tuberosity deficiency can be surgically challenging. Irrespective of the high complication rate, DLS use in patients with severe PHBL and severe tuberosity deficiency may provide favorable long-term glenohumeral reconstruction viability.Level of evidenceLevel IV.     

Accuracy and precision of placement of the glenoid baseplate in reverse total shoulder arthroplasty using a novel computer assisted navigation system combined with preoperative planning: A controlled cadaveric study

HypothesisRTSA glenoid baseplates will be placed more accurately and precisely with the use of preoperative planning and computer navigation compared to the use of preoperative planning and conventional freehand instrumentation alone.Material and methodsFive fellowship trained surgeons preoperatively planned 30 cadaveric scapulae (15 side matched pairs) for an RTSA baseplate using preoperative CT scans and a custom 3D templating software. The specimens were randomized with respect to side and were split into two equal cohorts. One cohort used preoperative planning and conventional freehand instrumentation to implant the baseplate, and the other cohort used preoperative planning and a CT based navigation system to implant the baseplate. Postoperative CT scans were taken, and accuracy and precision for baseplate position and angulation with respect to the preoperative plan was compared for both groups.ResultsGlenoid baseplates placed using the navigation system demonstrated significantly improved accuracy and precision of positioning, based on the preoperative plan, than those placed using conventional freehand instrumentation without navigation for version (1.9 ± 1.9° vs 5.9 ± 3.5°; P = 0.004) and inclination (2.4 ± 2.4° vs 6.3 ± 6.2°; P = 0.026), with a post hoc power > 95% (α = 0.05). No significant difference was noted for anterior/posterior (AP) positioning, superior/inferior (SI) positioning, and reaming depth. A lower standard deviation was observed for AP positioning in the navigated cohort (0.6 mm vs 1.3 mm; P = 0.017).ConclusionPreoperative planning combined with the navigation system used in this side matched pair cadaveric study is more accurate and precise in achieving the desired version and inclination of the glenoid baseplate in RTSA compared to preoperative planning combined with conventional freehand instrumentation alone. The system may offer less benefit improving AP or SI placement as well as reaming depth.     

Effects of increased retroversion angle on glenoid baseplate fixation in reverse total shoulder arthroplasty: a finite element analysis

BackgroundIncreased glenoid retroversion occurs in patients with severe arthritis but its effect on baseplate fixation of a reverse total shoulder arthroplasty (rTSA) is not clear. The purpose of this study is to determine the effects of increasing glenoid retroversion on baseplate fixation in rTSA using finite element analysis (FEA) modeling.MethodsFive sets of computerized tomographic images of healthy normal shoulders were selected and segmented with Amira (Thermo Fisher Scientific) to obtain the solid geometries. Scapula FEA models with 5°, 10°, 15°, 20°, and 25° retroversion angles were generated for each healthy scapula geometry and a rTSA glenoid baseplate was implanted on each model. Maximum stress at the anterior and posterior portions of the glenoid and the micromotion between the bone and baseplate were recorded. After simulation with normal scapular bone material properties (Young's modulus 4 GPa and Poisson's ratio 0.3), another set of simulations was run on each subject with a 25° retroversion angle and poor bone quality (Young's modulus 500 MPa and Poisson's ratio 0.3) to study a worst-case scenario. Micromotions in each model were also recorded. All statistical analysis was done with SPSS.ResultsSimulation results of models generated from the same subject but with different retroversion angles showed a clear pattern: as retroversion angle increased, the stresses increased posteriorly and decreased anteriorly. Also, micromotion between the bone and the baseplate increased with the increase of retroversion angle. With analysis of variance, we found that all three values change significantly as the retroversion angle increases (P< .001). The simulation results also showed that micromotion was large in shoulders with small glenoid size and poor bone quality. However, even in the model with the worst-case scenario (smallest glenoid size, poorest bone quality and 25° retroversion angle), the maximum micromotion and the maximum stresses are still within the safe range.DiscussionIn all cases with both normal and poor bone quality, the stresses and micromotion stayed below the threshold to allow for bone ingrowth of the glenoid baseplate to occur. Based on these results, for glenoid baseplates with a central peg/post and 4 screws for fixation, rTSA baseplate retroversion does not need to be corrected to less than 10° to provide good initial fixation as has been recommended for a cemented glenoid component and can withstand the initial stresses and micromotion up to 25° of retroversion.Level of evidenceBasic Science Study; Computer Modeling     

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

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

Preoperative differences in glenoid deformity,patient-determined outcomes,and range of motion as per disease type in shoulders undergoing total shoulder arthroplasty

BackgroundDiseases commonly treated with shoulder arthroplasty include the following: osteoarthritis, rotator cuff tear arthropathy (RCTA), and irreparable rotator cuff tears (IRCTs). Currently, there are few data available that identify if preoperative differences exist between these disorders in (1) computed tomography findings, (2) patient-determined outcome scores, and (3) range of motion. Understanding these disease-specific differences may allow for the development of disease-specific strategies in total shoulder arthroplasty to attempt to improve patient outcomes and implant longevity.MethodsA database of shoulders undergoing anatomic and reverse total shoulder arthroplasty was reviewed. The cohort was divided into three groups as per the disease treated with total shoulder arthroplasty: osteoarthritis, RCTA, and IRCT. The outcomes included preoperative range of motion, 3-dimensional computed tomography determination of glenoid morphology, and patient-determined outcomes including the Western Ontario Osteoarthritis Scale, American Shoulder and Elbow Surgeons score, Simple Shoulder Test, and the Single Assessment Numeric Evaluation. Differences between the groups were examined with analysis of variance with post hoc Tukey’s HSD test. The level of significance was P = .05.ResultsTwo hundred seventy-nine shoulders met inclusion and exclusion criteria. One hundred fifty-four shoulders had osteoarthritis, 94 shoulders had RCTA, and 21 shoulders had an IRCT. Patients with osteoarthritis had significantly greater mean glenoid retroversion (12.9°) than patients with an IRCT (7°; P = .03) and RCTA (8.6°; P = .004). Patients with osteoarthritis had significantly less mean superior glenoid inclination (5.9°) than patients with an IRCT (10.2°; P = .03) and RCTA (9.5°; P = .001). Patients with osteoarthritis had greater mean posterior humeral subluxation (68.9%) than patients with an IRCT (58.3%; P = .002) and RCTA (60.2%; P = .001).There was no difference in preoperative Western Ontario Osteoarthritis Scale (P = .86), American Shoulder and Elbow Surgeons score (P = .81), Simple Shoulder Test (P = .13), and Single Assessment Numeric Evaluation (P = .57). Patients with osteoarthritis had greater mean flexion (101°) than the IRCT (86°; P = .17) and RCTA groups (84°; P = .001). Patients with osteoarthritis had greater mean external rotation in the abducted position (54°) than the RCTA group (38°; P = .001) but similar to the IRCT group (48°; P = .68). The osteoarthritis group had inferior mean internal rotation in the abducted position (0.2°) compared with the RCTA (20.6°; P = .001). There were no differences in extension (P = .08), external rotation (P = .58), and abduction (P = .15).ConclusionShoulders with osteoarthritis have greater glenoid retroversion and posterior humeral subluxation, whereas shoulders with RCTA or IRCT have greater superior glenoid inclination. Patient-determined outcome scores do not differ between these diseases. Shoulders with osteoarthritis have greater baseline (1) flexion and (2) abducted external rotation but inferior abducted internal rotation.     

Magnetic resonance imaging and clinical findings before and after tendon transfers about the shoulder in children with residual brachial plexus birth palsy

The purpose of this study was to assess the magnetic resonance imaging (MRI) and clinical outcome after tendon transfers about the shoulder in children with residual brachial plexus birth palsy. Twenty-three children with an average age at surgery of 5.3 +/- 1.7 years underwent transfer of the latissimus dorsi and teres major to the posterior rotator cuff with or without concomitant musculotendinous lengthenings. Preoperative MRI revealed glenoid retroversion measuring -25.3 +/- 14.3 degrees and only 29.5 +/- 15.5% percent of humeral head anterior to the middle of the glenoid. Clinical evaluation showed significant improvements in external rotation and abduction. Postoperative MRI 1 year after surgery revealed no change in glenoid retroversion (-24.5 +/- 14.2) or percent of humeral head anterior to the middle of the glenoid (28.4 +/- 14.9%). These results demonstrate that tendon transfers improve overall shoulder motion but do not reduce humeral head subluxation or enhance glenohumeral joint realignment.     

Reverse Total Shoulder Arthroplasty for the Treatment of Defect Arthropathy

Abstract Objective: Total shoulder replacement for restoration of function and for pain relief of damaged glenohumeral joint accompanied by extensive irreparable cuff defect. Indications: Any painful shoulder arthropathy with insufficient and irreparable rotator cuff, especially primary defect arthropathy, rheumatoid arthritis with extensive rotator cuff defect, arthropathy after reconstruction of rotator cuff, mutilating rheumatoid arthritis, and crystal-induced arthropathy. Relative: failure of primary shoulder replacement in the presence of an irreparable cuff defect. Contraindications: Structural or neurogenic lesion of deltoid muscle. Advanced glenoid destruction. Relative: age < 65 years. Surgical Technique: Anterosuperior or deltopectoral approach. Exposure of glenoid. Resection of humeral head at epi-metaphyseal junction. Complete detachment of anterior, inferior, and posterior capsule from glenoid neck. Preparation of glenoid for cement-free fixation of glenoid base plate (metaglène). Preparation of humeral shaft for implantation of humeral component in 0–10° of retroversion. Screwing of glenosphere to base plate. Insertion of cemented or cement-free modular humeral component. Results: Between 10/1997 and 03/2001, a reverse total shoulder arthroplasty was done in 57 patients (14 men, 43 women; average age 70.1 years). Average follow-up time was 18.2 months. 98% of patients would agree to repeat surgery. Average Constant Score adjusted to age and gender was 94%, 97% for patients not having undergone previous surgery. All patients reported complete or almost complete freedom of pain. On the condition that the deltoid muscle was not damaged during previous surgery, a good improvement of power and function could be obtained. All functional parameters were normal for the patient’s age with the exception of a slight limitation of internal rotation (average L5). The power of maintained abduction also corresponded in general to age-specific values. Only grade 1 or 2 inferior glenoid notching was observed but never reaching or surpassing the inferior screw (grade 3 or 4); no glenoid base plate loosening. The following is a reprint from Operat Orthop Traumatol 2005;17:1–24 and continues the new series of articles at providing continuing education on operative techniques to the European trauma community. Reprint from: Operat Orthop Traumatol 2005;17:1–24. DOI 10.1007/s00064-005-1119-1     

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 and radiographic results of eccentric glenoid reaming in anatomical total shoulder arthroplasty using 3D planning and PSI

BackgroundTreatment of deformed type B glenoids with anatomical total shoulder arthroplasty (TSA) can be challenging when using standard imaging and instrumentation. 3D planning and PSI-guided (patient-specific instrumentation) eccentric reaming may substantially aid in both the glenoid correction and implantation of anatomical components in difficult cases. We hypothesized that the implementation of preoperative planning and a PSI-guided anatomical component protocol would result in accurate correction of the glenoid deformity and precise glenoid implant positioning.MethodsTwenty-two consecutive patients with primary glenohumeral osteoarthritis, intact rotator cuff and modified-Walch type B glenoids were treated with anatomical total shoulder arthroplasty. Preoperative 3D planning and PSI were used to guide eccentric reaming and correct glenoid deformity. Postoperative clinical and radiographic outcomes were assessed in all patients with a minimum follow-up of 2 years (mean of 26 months). Postoperative corrections of glenoid version and inclination were measured and the variation between preoperative planning and postoperative implant position was evaluated on CT 3D reconstructions. Similarly, both humeral subluxation in the axial scapular plane and glenoid joint line medialization were compared between preoperative and postoperative computed tomographic imaging.ResultsThe mean age was 57 years (range, 54-68). Significant improvements in pain and functional outcome measurements were seen in all 22 subjects. Mean native glenoid version and inclination were −15° ± 5° and 3° ± 5°, respectively. Postoperatively, version was corrected to −7° ± 6° and inclination to 1° ± 2°. Cortical central peg perforation was noted in 1 case and cement perforation in 3 cases. The mean deviation from the preoperative plan was 3° ± 3° for version and 2° ± 2° for inclination. Humeral head subluxation improved from 68% ± 6% to 37% ± 6% and re-centering on the glenoid implant was achieved in all cases. The mean executed medialization of the glenoid joint line was 6 ± 3 mm and proved accurate to within 1 ± 1 mm of the planned medialization. A strong linear correlation was found between the degree of correction of retroversion and the amount of medialization (R = 0.82; P< .001).Conclusion3D preoperative planning and PSI guided correction of deformed modified-type B glenoids resulted in accurate postoperative correction of the glenoid deformity, correct glenoid component implantation with low deviation from the planned position and excellent short-term functional and radiographic results.Level of Evidence: Level IV; Case Series; Treatment Study.     

Retroverted glenoid reconstruction using glenoid plate in reverse shoulder arthroplasty

Purpose

The objective of this study is to evaluate the clinical and radiological results of reverse shoulder arthroplasty (RSA) with glenoid plating in a consecutive series of patients affected by cuff tear glenohumeral arthropathy with glenoid retroversion >15°. We hypothesized that autologous humeral head graft may be better stabilized between the baseplate and the native glenoid surface with the use of a glenoid plate.

Methods

Twenty consecutive patients affected by cuff tear arthropathy with glenoid retroversion >15° (B2 or C according to Walch classification) were enrolled in this study. To reconstruct the glenoid, a dedicated plate was used in addition to the standard reverse shoulder baseplate and the glenosphere. Clinical and radiological assessment was performed using constant score (CS), subjective shoulder value (SSV), X-rays and CT scan at 6, 12 and 24 months of follow-up. Healing and resorption of the graft and detection of the glenoid version were assessed.

Results

Sixteen patients were available for final follow-up. The mean preoperative retroversion of the glenoid was 24°, while the post-op was 2° (p = 0.002). At 24 months of follow-up, mean CS and SSV were 61 and 70. Respect to preoperative scores, the results were statistically significant (p < 0.001). The last CT scan revealed: a complete healing of the graft in 100% of cases; graft resorption less than 25% in two patients (12.5%); glenoid retroversion of 4°. A negative statistically significant correlation was found between final CS and preoperative glenoid retroversion (0.039).

Conclusions

The present study reports the favorable outcomes of retroverted glenoid reconstruction with glenoid plates in RSA, an alternative method to address severe glenoid deficiency.

Level of evidence

Level IV, case series with no comparison group.

     

Total shoulder arthroplasty does not correct the orientation of the eroded glenoid

Background and purpose Alignment of the glenoid component with the scapula during total shoulder arthroplasty (TSA) is challenging due to glenoid erosion and lack of both bone stock and guiding landmarks. We determined the extent to which the implant position is governed by the preoperative erosion of the glenoid. Also, we investigated whether excessive erosion of the glenoid is associated with perforation of the glenoid vault.

Methods We used preoperative and postoperative CT scans of 29 TSAs to assess version, inclination, rotation, and offset of the glenoid relative to the scapula plane. The position of the implant keel within the glenoid vault was classified into three types: centrally positioned, component touching vault cortex, and perforation of the cortex.

Results Preoperative glenoid erosion was statistically significantly linked to the postoperative placement of the implant regarding all position parameters. Retroversion of the eroded glenoid was on average 10° (SD10) and retroversion of the implant after surgery was 7° (SD11). The implant keel was centered within the vault in 7 of 29 patients and the glenoid vault was perforated in 5 patients. Anterior cortex perforation was most frequent and was associated with severe preoperative posterior erosion, causing implant retroversion.

Interpretation The position of the glenoid component reflected the preoperative erosion and “correction” was not a characteristic of the reconstructive surgery. Severe erosion appears to be linked to vault perforation. If malalignment and perforation are associated with loosening, our results suggest reorientation of the implant relative to the eroded surface.     

Rotational evaluation of humeral shaft fractures with proximal extension fixed using the MIPO technique

IntroductionDiaphyseal fractures with proximal humeral extension can be treated using a helical model, so it is lateral on the proximal aspect and on the diaphyseal segment in the anterior surface.ObjectiveOur objective was to evaluate possible rotational deviations using minimally invasive plate osteosynthesis (MIPO) and to determine how it affects upper limb function.MethodsWe followed 11 patients for a period of two years. The proximal approach was anterior-lateral, and the distal approach was anterior, dividing the brachial muscle. For rotational evaluation, we used the semi-axial incidence described by Oztuna et al., assessing the degree of retroversion of the humeral head in relation to the elbow. During follow-up, we measured bilateral range of motion, shoulder function (UCLA), and upper limb function (DASH).ResultsFor patients whose final result was an increase in retroversion, there was an average difference of 9°, with an increase in the final difference of external rotation of 3° compared with the other shoulder, and no difference between the final levels of internal rotation. In the patients whose final result was a decrease in retroversion, where the distal fragment was fixed in internal rotation, the difference observed was an average of 6°. These patients had an average decrease of the external rotation of 5° with an increase of the internal rotation by two levels. The final functional scores were “good” and “excellent” in all patients, with a mean UCLA of 31.8 points (28–34) and a mean DASH of 9.11 points (0.83–22.2).ConclusionIn all patients, there was a difference in the humeral head retroversion compared to the contralateral limb, but with little clinical repercussion and good or excellent functional scores.