Computed tomography revealed the correlation between radiolucency and alignment of all-polyethylene pegged glenoid component more than 10 years after total shoulder arthroplasty in the Japanese population

BackgroundAnatomical total shoulder arthroplasty (TSA) provides successful long-term outcomes but complications can occur after 10 years that require revision. Computed tomography (CT) is a useful tool for assessing radiolucent lines around the glenoid component of TSA; however, the merits of long-term post-TSA follow up with CT are unclear. The purpose of this study was to evaluate the long-term outcomes after TSA of Japanese population and to identify factors related to radiolucency around the glenoid component using CT.MethodsA retrospective review was conducted of TSA patients who had completed at least 10 years of clinical follow up. Radiographs and CT images of the affected shoulder obtained at the last follow up were evaluated for radiolucent lines around the stem and each peg, superior inclination and retroversion of the glenoid component, subluxation index, and critical shoulder angle (CSA). Shoulder ROM, Constant–Murley score and UCLA score were compared between the preoperative and last follow up period.ResultsEighteen shoulders in 16 patients met the inclusion criteria. Mean patient age was 61 years, mean follow up period was 137 months, and mean Yian CT score was 19%. CT score was significantly highest in pegs located inferiorly (p < 0.05). Mean glenoid superior inclination was 12.6°, retroversion was ?0.3°, subluxation index was 46%, and CSA was 33.7°. Glenoid superior inclination was significantly lower (p = 0.007) in shoulders with possible loosening than in cases with no loosening (5.0° vs 15.6°). Mean Constant score and UCLA score improved significantly after TSA, from 25.8 to 10.7 points preoperatively to 70.1 and 28.9 points postoperatively, respectively. Mean shoulder flexion, internal rotation, and external rotation also showed improvement postoperatively.ConclusionTSA provides good long-term outcomes. Radiolucency was present most frequently around the inferior pegs of the glenoid component. Glenoid superior inclination may affect the formation of radiolucent lines around glenoid pegs.Level of evidenceLevel IV; Case Series; Treatment 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.     

Glenoid and scapulohumeral characteristics and their influence on preoperative range of motion and patient-determined outcomes

BackgroundIt is not clear if glenoid and scapulohumeral characteristics influence preoperative range of motion (ROM) and patient-determined outcomes. It is important to understand these interactions when planning and performing total shoulder arthroplasty in efforts of improving patient satisfaction and implant longevity.MethodsA retrospective review of patients that had three-dimensional computed tomography imaging for total shoulder arthroplasty was performed. Patients were separated into 2 groups determined by the presence (rotator cuff tear arthropathy [RCTA]) or absence (osteoarthritis [OA]) of an irreparable rotator cuff tear. Using the computed tomography measurements, shoulders were stratified by glenoid version (anteverted, normal, and retroverted), glenoid inclination (inferior, normal, and superior), and scapulohumeral subluxation (anterior, centered, and posterior) based on criteria determined from a review of the orthopedic literature. The Western Ontario Osteoarthritis Scale and the American Shoulder and Elbow Surgeons scores and ROM were determined preoperatively.ResultsIn OA patients (n = 154), version was associated with scapulohumeral subluxation (P < .0001). Retroverted glenoids had less flexion (96° vs. 108°; P = .049) and external rotation (15° vs. 21°; P = .04) compared with normal version. Inferiorly inclined glenoids had greater posterior subluxation (77%) than those with normal (67%; P = .001) and superior inclination (68%; P = .01). There were no relationships between excessive inclination or subluxation on ROM. In RCTA patients (n = 115), retroverted glenoids had greater superior inclination compared with normal glenoids (12.1° vs. 8.4°; P = .049). Version was associated with scapulohumeral subluxation (anteverted = mean 34% subluxation; normal version = 56.4% subluxation; retroverted = 71.2% subluxation; P < .0001). Retroverted glenoids had less flexion compared with normal version (70° vs. 90°; P = .048), less abduction (62°) than normal glenoids (88°; P = .03) and anteverted glenoids (115°; P = .03), and less abduction/internal rotation (7°) than normal (22°; P = .03) and anteverted glenoids (36°; P = .04). Superiorly inclined glenoids have more posterior subluxation than normally inclined glenoids (64% vs. 56.6%; P = .02). There was no relationship between inclination and ROM. Patients with posterior subluxation had less external rotation compared with those with a centered humeral head (10° vs. 22°; P = .009) and less abduction/internal rotation compared with anterior subluxation (12° vs. 35°; P = .02). There was no relationship between version, inclination, or subluxation with preoperative Western Ontario Osteoarthritis Scale or American Shoulder and Elbow Surgeons in patients with OA (P > .17) or RCTA (P > .31).ConclusionsAn interaction between version, inclination, and scapulohumeral subluxation in patients with OA and RCTA was found. Retroverted glenoids had decreased ROM measurements. RCTA shoulders with posterior scapulohumeral subluxation had decreased ROM. There was no relationship between glenoid and scapulohumeral morphology and patient-determined outcome scores.Level of evidenceLevel III; Retrospective Case-Control Prognosis Study     

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.     

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.     

Assessing glenoid arthroplasty component positioning for surgeons utilizing surgical planning software

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

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.     

Arthroscopic glenoid removal for aseptic loosening in total shoulder arthroplasty

BackgroundGlenoid loosening is the most common long-term complication of total shoulder arthroplasty (TSA) and frequently necessitates revision. Though arthroscopic glenoid removal is an accepted treatment option for glenoid loosening, there is a paucity of outcomes literature available. The purpose of this study was to report the long-term clinical and radiographic outcomes of arthroscopic glenoid removal for failed or loosened glenoid component in TSA. We hypothesized that arthroscopic glenoid removal would produce acceptable clinical and patient-reported outcomes while limiting the need for further revisions.MethodsThis was a retrospective analysis of 11 consecutive patients undergoing 12 arthroscopic glenoid removals for symptomatic glenoid loosening by a single orthopedic surgeon between March 2005 and March 2018. Indication for arthroscopic glenoid removal included symptomatic glenoid loosening with radiographic evidence of a 1-2 mm radiolucent line around the glenoid. Shoulder range of motion, functionality (American Shoulder and Elbow Surgeons, Simple Shoulder Test), and pain (visual analog scale [VAS]) were evaluated. Radiographs were assessed for glenohumeral subluxation, humeral superior migration, and glenohumeral offset following glenoid removal.ResultsThe mean follow-up period since arthroscopic glenoid removal was 55 months (range, 20-172 months). Glenoid component removal significantly reduced forward elevation, with a mean decrease from 147 ± 13° preoperatively to 127 ± 29° postoperatively (P= .031). However, there was no significant change in external rotation (44 ± 9° vs. 43 ± 19°; P= .941) or internal rotation (L4 vs. L4; P= .768). Importantly, glenoid removal significantly decreased VAS pain scores from 7 ± 3 preoperatively to 5 ± 3 postoperatively (P= .037). Additionally, improvement in ASES approached statistical significance, increasing from 33 ± 25 preoperatively to 53 ± 28 postoperatively (P= .055). With regard to radiographic outcomes, there was no evidence of glenohumeral subluxation and humeral superior migration developed in 1 patient. However, there was significant medialization of the greater tuberosity relative to the acromion, with a mean lateral offset of 6 ± 7 mm preoperatively and −2 ± 4 mm postoperatively (P= .002). Two patients required conversion to reverse TSA for persistent pain. There were no complications.DiscussionThese findings suggest that arthroscopic glenoid removal for symptomatic glenoid loosening is a viable option to improve pain while limiting the need for additional reoperations and decreasing the risks associated with revision arthroplasty. However, continual follow-up to monitor medialization is recommended.Level of EvidenceLevel IV; Case Series; Treatment Study     

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.     

Quantitative statistical shape model-based analysis of humeral head migration,Part 2: Shoulder osteoarthritis

We wanted to investigate the quantitative characteristics of humeral head migration (HHM) in shoulder osteoarthritis (OA) and their possible associations with scapular morphology. We quantified CT-scan-based-HHM in 122 patients with a combination of automated 3D scapulohumeral migration (=HHM with respect to the scapula) and glenohumeral migration (=HHM with respect to the glenoid) measurements. We divided OA patients in Group 1 (without HHM), Group 2a (anterior HHM) and Group 2b (posterior HHM). We reconstructed and measured the prearthropathy scapular anatomy with a statistical shape model technique. HHM primarily occurs in the axial plane in shoulder OA. We found “not-perfect” correlation between subluxation distance AP and scapulohumeral migration values (r_s = 0.8, p < 0.001). Group 2b patients had a more expressed prearthropathy glenoid retroversion (13° vs. 7°, p < 0.001) and posterior glenoid translation (4 mm vs. 6 mm, p = 0.003) in comparison to Group 1. Binary logistic regression analysis indicated prearthropathy glenoid version as a significant predictor of HHM (χ² = 27, p < 0.001). Multivariate regression analysis showed that the pathologic version could explain 56% of subluxation distance-AP variance and 75% of the scapulohumeral migration variance (all p < 0.001). Herewith, every degree increase in pathologic glenoid retroversion was associated with an increase of 1% subluxation distance-AP, and scapulohumeral migration. The occurrence of posterior HHM is associated with prearthropathy glenoid retroversion and more posterior glenoid translation. The reported regression values of HHM in the function of the pathologic glenoid version could form a basis toward a more patient-specific correction of HHM.     

The effect of glenoid version on internal and external rotation in reverse total shoulder arthroplasty

BackgroundThere is currently limited understanding of the contribution of glenoid version to postoperative internal (IR) and external rotation (ER) after reverse total shoulder arthroplasty (RTSA). The purpose of this study was to determine the impact of glenoid version on postoperative rotation after RTSA.MethodsForty-five 3-dimensional (3D) computer models of human scapulae were created from de-identified computed tomography (CT) scans. The scapulae were divided into 3 separate groups based on glenoid version: normal (10° to -10°), moderate (-10 to -25°), and severe (< -25°). The scapulae then underwent virtual implantation with a Grammont-style RTSA prosthesis at either 0°, -20°, or -30° of retroversion based on the severity of the native glenoid version (normal, moderate, severe). Internal, external, and total rotation (TR) were determined for each construct at both 30° and 60° of humeral abduction.ResultsGlenoids with a narrow width (< 25 mm) were noted to have minimal bony impingement on rotational testing and were excluded. In the remaining scapulae (n = 34), the achievable TR and IR for the humeral component decreased as glenoid retroversion increased. Changes in rotation for all categories were in general more pronounced at 60° of humeral abduction. Overall, ER generally increased as glenoid retroversion increased, with the largest increase occurring when going from 0° to -20° of retroversion, and minimal increase from -20° to -30° of retroversion regardless of humeral abduction.ConclusionPlacement of the glenoid component in increasing retroversion during RTSA results in a loss of IR and a corresponding increase in ER.Level of EvidenceBasic Science Study     

Significant variability exists in preoperative planning software measures of glenoid morphology for shoulder arthroplasty

Background & HypothesisWe sought to assess the reliability of 4 different shoulder arthroplasty 3-dimensional preoperative planning programs. Comparison was also made to manual measurements conducted by 2 fellowship-trained musculoskeletal radiologists. We hypothesized that there would be significant variation in measurements of glenoid anatomy affected by glenoid deformity.MethodsA retrospective review of computed tomography (CT) scans of patients undergoing shoulder arthroplasty was undertaken. A total of 76 computed tomographies were analyzed for glenoid version and inclination by 4 templating software systems (VIP, Blueprint, TrueSight, ExactechGPS). Inter-rater reliability was assessed via intra-class correlation coefficient (ICC). For those shoulders with glenohumeral arthritis (58/76), ICC was also calculated when sub-grouping by modified Walch classification. Lin's concordance correlation coefficient was calculated for each system with 2 musculoskeletal-trained radiologists’ measurements.ResultsMeasurements of glenoid version and inclination differed between at least 2 programs by 5º-10º in 75% and 92% of glenoids respectively, and by >10º in 18% and 45% respectively. ICC was excellent for version but only moderate for inclination. ICC was highest among Walch A glenoids for both version (near excellent) and inclination (good), and lowest among Walch D for version (near poor) and Walch B for inclination (moderate). When measuring version, VIP had the highest concordance with manual measurement; Blueprint had the lowest. For inclination Blueprint had the highest concordance; ExactechGPS had the lowest.Discussion & ConclusionDespite overall high reliability for measures of glenoid version between 4 frequently utilized shoulder arthroplasty templating softwares, this reliability is significantly affected by glenoid deformity. The programs were overall less reliable when measuring inclination, and a similar trend of decreasing reliability with increasing glenoid deformity emerged that was not statistically significant. Concordance with manual measurement is also variable. Further research is needed to understand how this variability should be accounted for during shoulder arthroplasty preoperative planning.Level of EvidenceLevel III; Retrospective Comparative Study     

3D preoperative planning for shoulder arthroplasty: an evaluation of different planning software systems

BackgroundOptimal glenoid component positioning in shoulder arthroplasty can sometimes be challenging. 3D preoperative planning and patient-specific instruments can help position the glenoid component more accurately. Multiple medical companies have developed their method of performing preoperative glenoid measurements. The goal of this study was to compare those different measurement techniques for inclination and version measurements.MethodsCT scans of 13 cadaveric shoulders were used for 3D analysis. All CT scans were sent to different companies that agreed to participate in this study. Each company was expected to report on their methods and measure the preoperative glenoid inclination and version. Furthermore, the researchers calculated preoperative inclination and version of these shoulders using 2 different methods. The measurements were statistically analyzed to determine differences between all methods in a pairwise manner.ResultsSix methods were evaluated in a pairwise manner, resulting in 15 pairs being analyzed. 10 pairs differed significantly for inclination (P < .008), and 4 pairs differed significantly for version (P < .008).ConclusionThere are significant differences between measurement techniques concerning preoperative glenoid inclination and version. The knowledge that different companies use different measurement techniques for preoperative 3D planning of shoulder surgery is essential and should be taken into account when using different planning systems.Level of evidenceLevel III; Study of Diagnostic Test     

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     

Computerized 3D morphological analysis of glenoid orientation

An accurate preoperative measurement of glenoid orientation is crucial for evaluating pathologies and successful total shoulder arthroplasty. Existing methods may be labor‐intensive, observer‐dependent, and sensitive to the misalignment between the scapula plane and CT scanning direction. In this study, we proposed a computation framework and performed an automated analysis of the glenoid orientation based on 3D surface data. Three‐dimensional models of 12 scapulae were analyzed. The glenoid cavity and external anatomical features were automatically extracted from these 3D models. Glenoid version was calculated using the scapula plane and the fulcrum axis alternatively. Glenoid inclination was measured both relative to transverse axis of the scapula and the medial pole‐inferior tip axis. The mean (±SD) of the fulcrum‐based glenoid version was ?0.55° (±4.17°), while the scapular‐plane‐based glenoid version was ?5.05° (±3.50°). The mean (±SD) of glenoid inclinations based on the medial pole and inferior tip was 12.75° (±5.03°) while the mean (±SD) of the glenoid inclination based on the medial pole and glenoid center was 4.63° (±4.86°). Our computational framework was able to extract the reproducible morphological measures free of inter‐ and intra‐ observer variability. For the first time in 3D, we showed that the fulcrum axis was practically perpendicular to the glenoid plane normal (radial line), and thus extended the fulcrum‐based glenoid version for quantifying 3D glenoid orientation. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:692–698, 2016.

     

An optimised method for quantifying glenoid orientation

A robust quantification method is essential for inter-subject glenoid comparison and planning of total shoulder arthroplasty. This study compared various scapular and glenoid axes with each other in order to optimally define the most appropriate method of quantifying glenoid version and inclination.Six glenoid and eight scapular axes were defined and quantified from identifiable landmarks of twenty-one scapular image scans. Pathology independency and insensitivity of each axis to inter-subject morphological variation within its region was tested. Glenoid version and inclination were calculated using the best axes from the two regions.The best glenoid axis was the normal to a least-square plane fit on the glenoid rim, directed approximately medio-laterally. The best scapular axis was the normal to a plane formed by the spine root and lateral border ridge. Glenoid inclination was 15.7° ± 5.1° superiorly and version was 4.9° ± 6.1°, retroversion.The choice of axes in the present technique makes it insensitive to pathology and scapular morphological variabilities. Its application would effectively improve inter-subject glenoid version comparison, surgical planning and design of prostheses for shoulder arthroplasty.     

Measurement of glenoid version: conventional radiographs versus computed tomography scans

Glenoid version seems to play an important role in the stability and loading of the glenohumeral joint. The purpose of this study was to compare measurements of glenoid version on axillary views and computed tomography (CT) scans. Radiographs and CT scans of 25 patients evaluated predominantly for glenohumeral joint instability and 25 patients after implantation of a total shoulder prosthesis were analyzed by 3 independent observers. In all patients glenoid version was determined on an axillary view and on a CT scan at the mid-glenoid level. The mean glenoid version measured on CT scans was 3 degrees of retroversion in the instability group (range, 7 degrees of anteversion to 16 degrees of retroversion) and 2 degrees of anteversion in the total shoulder prosthesis group (range, 16 degrees of anteversion to 23 degrees of retroversion). Glenoid retroversion was overestimated on plain radiographs in 86%. The mean difference between measurements of glenoid version on axillary views and CT cuts was 6.5 degrees (range, 0 degrees -21 degrees ), and the coefficient of correlation between these measurements was 0.33 in the instability group and 0.67 in the prosthesis group. In conclusion, glenoid version cannot be determined accurately on standard axillary radiographs, either preoperatively or postoperatively. Studies that assess the role of glenoid component orientation should use a reproducible method of assessment such as CT.     

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

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