Glenoid Position Research Articles

Deltopectoral approach without subscapularis detachment for reverse shoulder arthroplasty. Technique and results of a safe and reproducible subscapularis-sparing approach

AimsThe importance of the subscapularis for reverse total shoulder arthroplasty (rTSA) has been demonstrated, especially for internal rotation and stability. In a deltopectoral approach, a detachment of the subscapularis is performed (tenotomy, tuberosity peeling or osteotomy) but the tendon is not always repairable at the end. When it is repaired, healing is obtained in only 40% to 76% of the cases, with potential consequences for the outcomes. The Anterior Muscle-Sparing (AMS) approach is a deltopectoral approach with preservation of the subscapularis, providing a solution to these problems. We present the surgical technique and results. MethodsIn a retrospective study, we included our first 45 cases of rTSA performed with the AMS approach for a degenerative affection of the shoulder (massive rotator cuff tear, cuff tear arthropathy, primary glenohumeral arthritis, rheumatoid arthritis), excluding traumatic and revision cases. The subscapularis was intact in all the cases. The mean age at inclusion was 74.1 years. No patients were lost at the minimum 24-month follow-up. All the patients underwent a clinical evaluation preoperatively and at the last follow-up, including Constant score, simple shoulder value (SSV), pain scale, and range of motion. An X-ray evaluation was conducted postoperatively and at the last follow-up to assess implant positioning and evolution. ResultsThere was no intraoperative complication, and the mean operative time was 62 minutes. We observed a significant improvement in Constant score (from 36 to 70, p <.001), SSV (from 33 to 81, p <.001), pain (from 6.3 to 0.7, p <.001), strength (from 0.5 to 3.5, p <.001), and most of the active mobilities. Regarding internal rotation, 95% of the patients reached level L3 or higher. Glenoid positioning was considered optimal in more than 90% of the cases (inferior tilt and low position) without any occurrence of superior tilt or high position. The osteophytes could be totally removed in 8 out of 9 cases (88.9%). Six postoperative complications (13.3%) were reported: 1 infection (2.2%), 2 cases of traumatic glenoid loosening (4.4%), 2 acromion fractures (4.4%), and 1 hematoma (2.2%). There was no instability. Eighty percent of the patients could return home, with a mean hospital stay of 1.8 days. ConclusionThe AMS approach is a safe and reproducible technique. The preservation of the subscapularis has potential benefits regarding internal rotation and stability. In the absence of tendon suture, rehabilitation can be started immediately without motion restriction, allowing for a fast recovery and return to autonomy.

Optimizing range of motion in reverse shoulder arthroplasty.

Optimal glenoid positioning in reverse shoulder arthroplasty (RSA) is crucial to provide impingement-free range of motion (ROM). Lateralization and inclination correction are not yet systematically used. Using planning software, we simulated the most used glenoid implant positions. The primary goal was to determine the configuration that delivers the best theoretical impingement-free ROM. With the use of a 3D planning software (Blueprint) for RSA, 41 shoulders in 41 consecutive patients (17 males and 24 females; means age 73 years (SD 7)) undergoing RSA were planned. For the same anteroposterior positioning and retroversion of the glenoid implant, four different glenoid baseplate configurations were used on each shoulder to compare ROM: 1) no correction of the RSA angle and no lateralization (C-L-); 2) correction of the RSA angle with medialization by inferior reaming (C+M+); 3) correction of the RSA angle without lateralization by superior compensation (C+L-); and 4) correction of the RSA angle and additional lateralization (C+L+). The same humeral inlay implant and positioning were used on the humeral side for the four different glenoid configurations with a 3 mm symmetric 135° inclined polyethylene liner. The configuration with lateralization and correction of the RSA angle (C+L+) led to better ROM in flexion, extension, adduction, and external rotation (p ≤ 0.001). Only internal rotation was not significantly different between groups (p = 0.388). The configuration where correction of the inclination was done by medialization (C+M+) led to the worst ROM in adduction, extension, abduction, flexion, and external rotation of the shoulder. Our software study shows that, when using a 135° inlay reversed humeral implant, correcting glenoid inclination (RSA angle 0°) and lateralizing the glenoid component by using an angled bony or metallic augment of 8 to 10 mm provides optimal impingement-free ROM.

Mixed-reality improves execution of templated glenoid component positioning in shoulder arthroplasty: a CT imaging analysis

Glenoid placement is critical for successful outcomes in total shoulder arthroplasty (TSA). Preoperative templating with three-dimensional imaging has improved implant positioning, but deviations from the planned inclination and version still occur. Mixed-Reality (MR) is a novel technology that allows surgeons intra-operative access to three-dimensional imaging and templates, capable of overlaying the surgical field to help guide component positioning. The purpose of this study was to compare the execution of preoperative templates using MR vs.standard instruments (SIs). Retrospective review of 97 total shoulder arthroplasties (18 anatomic, 79 reverse) from a single high-volume shoulder surgeon between January 2021 and February 2023, including only primary diagnoses of osteoarthritis, rotator cuff arthropathy, or a massive irreparable rotator cuff tear. To be included, patients needed a templated preoperative plan and then a postoperative computed tomography scan. Allocation to MR vs. SI was based on availability of the MR headset, industry technical personnel, and the templated preoperative plan loaded into the software, but preoperative or intraoperative patient factors did not contribute to the allocation decision. Postoperative inclination and version were measured by two independent, blinded physicians and compared to the preoperative template. From these measurements, we calculated the mean difference, standard deviation (SD), and variance to compare MR and SI. Comparing 25MR to 72 SI cases, MR significantly improved both inclination (P<.001) and version (P<.001). Specifically, MR improved the mean difference from preoperative templates (by 1.9° inclination, 2.4° version), narrowed the SD (by 1.7° inclination, 1.8° version), and decreased the variance (11.7-3.0 inclination, 14.9-4.3 version). A scatterplot of the data demonstrates a concentration of MR cases within 5° of plan relative to SI cases typically within 10° of plan. There was no difference in operative time. MR improved the accuracy and precision of glenoid positioning. Although it is unlikely that 2° makes a detectable clinical difference, our results demonstrate the potential ability for technology like MR to narrow the bell curve and decrease the outliers in glenoid placement. This will be particularly relevant as MR and other similar technologies continue to evolve into more effective methods in guiding surgical execution.

Biomechanical Characteristics of Glenosphere Orientation Based on Tilting Angle and Overhang Changes in Reverse Shoulder Arthroplasty.

Glenoid position and inclination are important factors in protecting against scapular notching, which is the most common complication that directly affects the longevity of reverse shoulder arthroplasty (RSA). This study aimed to investigate the biomechanical characteristics of glenosphere orientation, comparing neutral tilt, inferior overhang with an eccentric glenosphere at the same placement of baseplate, and inferior tilt after 10° inferior reaming in the lower part of the glenoid in RSA. Nine cadaveric shoulders were tested with 5 combinations of customized glenoid components: a centric glenosphere was combined with a standard baseplate (group A); an eccentric glenosphere to provide 4-mm inferior overhang than the centric glenosphere was combined with a standard baseplate (group B); a centric glenosphere was combined with a wedge-shaped baseplate tilted inferiorly by 10° with the same center of rotation (group C); an eccentric glenosphere was attached to a wedge-shaped baseplate (group D); and 10° inferior reaming was performed on the lower part of the glenoid to apply 10° inferior tilt, with a centric glenosphere secured to the standard baseplate for simulation of clinical tilt (group E). Impingement-free angles for adduction, abduction, forward flexion, external rotation, and internal rotation were measured. The capability of the deltoid moment arm for abduction and forward flexion, deltoid length, and geometric analysis for adduction engagement were evaluated. Compared with neutral tilt, inferior tilt at the same position showed no significant difference in impingement-free angle, moment arm capability, and deltoid length. However, group D resulted in better biomechanical properties than a central position, regardless of inferior tilt. Group E demonstrated a greater range of adduction, internal and external rotation, and higher abduction and forward flexion capability with distalization, compared to corresponding parameters for inferior tilt with a customized wedge-shaped baseplate. A 10° inferior tilt of the glenosphere, without changing the position of the baseplate, had no benefit in terms of the impingement-free angle and deltoid moment arm. However, an eccentric glenosphere had a significant advantage, regardless of inferior tilt. Inferior tilt through 10° inferior reaming showed better biomechanical results than neutral tilt due to the distalization effect.

Inverted-Bearing Reverse Shoulder Arthroplasty: Consequences on Scapular Notching and Clinical Results at Mid-Term Follow-Up.

Background: Scapular notching following reverse shoulder arthroplasty (RSA) is caused by both biological and mechanical mechanisms. Some authors postulated that osteolysis that extends over the inferior screw is caused mainly by biological notching. Inverted-bearing RSA (IB-RSA) is characterized by a polyethylene glenosphere and a metallic humeral liner, decreasing the poly debris formation and potentially reducing high grades of notching. This study aims to report the results of IB-RSA on a consecutive series of patients at mid-term follow-up, focusing on the incidence of Sirveaux grade 3 and 4 scapular notching. Methods: A retrospective study on 78 consecutive patients who underwent primary IB-RSA between 2015–2017 was performed. At a 4 years minimum follow-up, 49 patients were evaluated clinically with Constant score (CS), Subjective shoulder value (SSV), American Shoulder and Elbow score (ASES), pain and range of motion, and with an X-ray assessing baseplate position (high, low), implant loosening, and scapular notching. Results: At a mean follow-up of 5.0 ± 0.9, all the clinical parameters improved (p < 0.05). One patient was revised for an infection and was excluded from the evaluation, two patients had an acromial fracture, and one had an axillary neuropraxia. Scapular notching was present in 13 (27%) patients (six grade 1, seven grade 2) and no cases of grade 3 and 4 were observed. Scapular nothing was significantly associated with high glenoid position (p < 0.001) and with lower CS (70 ± 15 vs. 58 ± 20; p = 0.046), SSV (81 ± 14 vs. 68 ± 20; p = 0.027), ASES (86 ± 14 vs. 70 ± 22; p = 0.031), and anterior elevation (148 ± 23 vs. 115 ± 37; p = 0.006). A 44 mm- compared to 40 mm-glenosphere was associate with better CS (63 ± 17 vs. 78 ± 11; p = 0.006), external (23 ± 17 vs. 36 ± 17; p = 0.036), and internal rotation (4.8 ± 2.7 vs. 7.8 ± 2.2; p = 0.011). Conclusions: IB-RSA is a safe and effective procedure for mid-term follow-up. Inverting biomaterials leads to a distinct kind of notching with mainly mechanical features. Scapular notching is associated with a high baseplate position and has a negative influence on range of motion and clinical outcome.

Implant Sizing and Positioning in Anatomical Total Shoulder Arthroplasty Using a Rotator Cuff-Sparing Postero-Inferior Approach.

Background: The goal of this study was to compare the effectiveness of a rotator cuff-sparing postero-inferior (PI) approach with subdeltoidal access to the traditional subscapularis-takedown deltopectoral approach, in terms of implant sizing and positioning in anatomical total shoulder arthroplasty (aTSA). Methods: This study involved 18 human cadaveric shoulders with intact rotator cuffs and no evidence of head deforming osteoarthritis. An Eclipse stemless aTSA (Arthrex, Naples, FL, USA) was implanted in nine randomly selected specimens using a standard subscapularis-tenotomy deltopectoral approach, and in the other nine specimens using the cuff-sparing PI approach. Pre- and postoperative antero-posterior (AP) and axillary fluoroscopic radiographs were analyzed by two independent, blinded raters for the following parameters: (1) anatomic and prosthetic neck-shaft angle (NSA); (2) the shift between the anatomic and prosthetic center of rotation (COR); (3) anatomical size matching of the prosthetic humeral head; (4) the calculated Anatomic Reconstruction Score (ARS); (5) glenoid positioning; as well as (6) glenoid inclination and version. Results: While the COR was slightly but significantly positioned (p = 0.031) to be more medial in the PI approach group (3.7 ± 3.4%, range: −2.3% to 8.7%) than in the deltopectoral approach group (−0.2 ± 3.6%, range: −6.9% to 4.1%), on average, none of the remaining measured radiographic parameters significantly differed between both groups (PI approach group vs. deltopectoral group: NSA 130° vs. 127°, p = 0.57; COR supero-inferior, 2.6% vs. 1.0%, p = 0.35; COR antero-posterior, 0.9% vs. 1.7%, p = 0.57; head size supero-inferior, 97.3% vs. 98.5%, p = 0.15; head size antero-posterior, 101.1% vs. 100.6%, p = 0.54; ARS, 8.4 vs. 9.3, p = 0.13; glenoid positioning supero-inferior, 49.1% vs. 51.1%, p = 0.33; glenoid positioning antero-posterior, 49.3% vs. 50.4%, p = 0.23; glenoid inclination, 86° vs. 88°, p = 0.27; and glenoid retroversion, 91° vs. 89°, p = 0.27). Conclusions: A PI approach allows for sufficient exposure and orientation to perform rotator-cuff sparing aTSA with acceptable implant sizing and positioning in cadaveric specimens.

Patient-specific Instrumentation Versus Standard Surgical Instruments in Primary Reverse Total Shoulder Arthroplasty: A Retrospective Comparative Clinical Study.

AimsPatient-specific instrumentation (PSI) in primary shoulder arthroplasty has been studied; results supported the positive impact of the PSI on the glenoid positioning. Nevertheless, no clinical outcomes have been reported. We compare the clinical outcomes of primary reverse total shoulder arthroplasty using PSI versus the standard methods.MethodsFifty-three patients with full records and a minimum of 24-months follow-up were reviewed, 35 patients received primary standard RSTA, and 18 patients received primary PSI RSTA. All patients were operated on in a single center. The median follow-up was 46 months (53 months in the standard group vs 39 months in the PSI group).ResultsThere was an overall significant post-operative improvement in the whole cohort (P< 0.05). The standard group had more deformed glenoids (B2, B3, C&D) and significantly low preoperative constant score and forward flexion (P=0.02 & 0.034). Compared to the PSI group (all were A1, A2, B1 &one type D), there were no statistically significant differences in any clinical outcome postoperatively. PSI neither prolonged the waiting time to surgery (P=0.693) nor the intraoperative time (P=0.962). Radiologically, PSI secured a higher percentage of optimum baseplate position and screw anchorage; however, no statistical correlation was found.ConclusionIn this series, both groups achieved comparable good outcomes. PSI did not achieve significantly better clinical outcomes than Standard after primary RSTA. Yet comparison has some limitations. PSI did not negatively impact the waiting time or the surgical time.

Glenoid Component Position Does Not Affect Short-Term Clinical and Radiologic Outcomes in Total Shoulder Arthroplasty.

Background: Malpositioning of the glenoid component in total shoulder arthroplasty (TSA) remains the primary source of loosening. The purpose of this study is firstly, to quantify postoperative glenoid component position in patients having a TSA and secondly, to explore whether glenoid component radiolucency is associated with glenoid position, clinical outcomes and patient-reported measures in the short-term (two year) follow-up period. Methods: This study was a sub-study of a larger clinical trial that included patients who underwent a TSA and who were randomized into two different glenoid types with a minimum two-year follow-up period. Post-operative radiographic assessments (six weeks and two years) were used to measure glenoid component position (version, inclination, offset) and humeral head centering anterior–posterior (AP) and superior–inferior (SI), and to assess glenoid component radiolucent scoring (modified Lazarus). Pre-operative X-rays were used to measure glenoid version, inclination and Walch classification. Patient-reported measures (PROMs) included the EQ-5D health slider and the Western Ontario Osteoarthritis (WOOS) and American Shoulder and Elbow Surgeons (ASES) score and were captured at baseline and two years postoperative. Clinical outcomes including range of motion and complications were also documented. Statistical analysis included t-tests and regression modeling. Results: Ninety-one patients with an average age of 69.9 ± 6.2 years were included in this study. Glenoid component position improved significantly in version (−19.4 ± 8.6° to −17.7 ± 8.5°; p < 0.045) and inclination (11.5 ± 7.1° to 5.9 ± 6.3°; p < 0.00001) from preoperative to six weeks postoperative. Glenoid component offset in SI and humeral head centering in AP remained unchanged throughout the follow-up. Radiolucency (Lazarus classification) was recorded in 21 cases (17.3%) with a Lazarus score of 1 (15 cases) and 2 (6 cases). The EQ-5D health slider, WOOS and ASES, and ROM confirmed continuous improvements from the preoperative scores to the two-year follow-up (p < 0.05). Regression models showed no correlation between glenoid component radiolucency at two years and the postoperative week six glenoid component position; however, female gender was a significant variable. Conclusion: Glenoid component changes from its original native glenoid were observed following TSA. Glenoid inclination was improved more than version from baseline, and the humeral head remained well-centered in AP and SI at two years. Radiolucency of the glenoid at two years is not negatively associated with PROMs or component position; however, female gender was identified as a significant predictor and warrants further investigation. Complications are not associated with glenoid position or radiolucency, but longer-term follow-up is required.

Glenoid fossa position in skeletal class-II malocclusion due to retrognathic mandible and skeletal class-I malocclusion in Pakistani population

BACKGROUND &amp; OBJECTIVE: Different dental and skeletal abnormalities interact with each other to cause multiple malocclusions of various areas of the dentofacial region. Association of the mandible and cranial base influence the malocclusions in anteroposterior and vertical dimensions that influences the evaluation of the skeletal components of a particular patient, so the relationship of glenoid fossa to adjacent craniofacial components must be taken into account. This research is conducted for the comparison of glenoid fossa position in subjects presenting with class II skeletal malocclusion due to retrognathic mandible and class I skeletal malocclusion.&#x0D; METHODOLOGY: Standardized lateral cephalograms of 130 patients were selected according to inclusion criteria from the orthodontic department. These radiographs were traced, and different angular and linear measurements were recorded. Then the position of glenoid fossa was compared in subjects of class II malocclusion with retrognathic mandible and class I malocclusion. SPSS version 17 was used for data analysis. Cephalometric measurements were analyzed, and glenoid fossa position was compared in both groups by using student’s t-test. Statistical level of significance using student t test was p&lt; 0.05&#x0D; RESULTS: Position of glenoid fossa in subjects with class II malocclusion is more distal and posterior as compared to the subjects with class I malocclusion. The effective parameters for the measurements of glenoid fossa are GF-S on FH, GF-Ptm on FH, and GF-FMN with p value 0.0001.&#x0D; CONCLUSION: A distally and posteriorly placed glenoid fossa is an important diagnostic feature of Class II skeletal malocclusion with the retrognathic mandible.&#x0D;

Does fluoroscopy improve baseplate position compared to conventional technique in reverse shoulder arthroplasty? A preliminary study.

Accurate placement of glenoid component in reverse shoulder arthroplasty remains a challenge for surgeons of all levels of expertise; however, no studies have evaluated the utility of fluoroscopy as a surgical assistance method. Prospective comparative study of 33 patients undergoing primary reverse shoulder arthroplasty during a 12-month period. Fifteen patients had a baseplate placed using the conventional "free hand" technique (control group), and 18 patients using intraoperative fluoroscopy assistance group, in a case-control design. Postoperative glenoid position was evaluated on postoperative Computed Tomography (CT) scan. The mean deviation of version and inclination for fluoroscopy assistance vs. control group was 1.75° (0.675-3.125) vs. 4.2° (1.975-10.45) (p = .015), and 3.85° (0-7.225) vs. 10.35° (4.35-18.75) (p = .009). The distance from the central peg midpoint to the inferior glenoid rim (fluoroscopy assistance 14.61 mm/control 4.75 mm, p = .581) and the surgical time (fluoroscopy assistance 1.93 ± 0.57/control 2.18 ± 0.44 h, p = .400) showed no differences, with an average radiation dose of 0.45 mGy and fluoroscopy time of 14 s. Accurate axial and coronal scapular plane positioning of glenoid component is improved with intraoperative fluoroscopy at the cost of a greater radiation dose and without differences in surgical time. Comparative studies are needed to determine whether their use in relation to more expensive surgical assistance systems result in similar effectiveness.L evel of evidence : Level III, therapeutic study.

Computer-Assisted Surgery in Reverse Shoulder Arthroplasty: Early Experience.

In the last decade, new technologies have been applied to shoulder arthroplasty. The aim of this work was to show that navigated RSA allows the surgeon to reach the planned version/inclination in all cases. In this article are shown preliminary data, advantages, disadvantages and limits of the technique. Eighteen computer-assisted reverse shoulder arthroplasty were performed. Preoperative glenoid version and inclination were evaluated with preoperative CT scan using Orthoblue® (Exactech, Gainesville, FL,USA) software, as well as baseplate type, planned glenoid component seating, planned postoperative version, planned postoperative inclination, intraoperative glenoid version/inclination, screw length and surgical time. A senior shoulder surgeon has analyzed the advantages, disadvantages and limitation of this kind of surgery. Mean surgical time of the primary implants was 92 ± 12min (min 75-max 110). Mean preoperative inclination was + 2.6° ± 6.4, mean preoperative version was -7.6° ± 8.4. Mean planned postoperative inclination was -2.7° ± 2.3, mean planned postoperative version was -1.6° ± 2.9 and mean planned glenoid seating was 89% ± 8%. Planned settings were reached in all cases during surgery. Baseplate implanted were in nine cases 8° posterior augmented, in six cases standard and in three cases 10° superior augmented. Mean screw length was 33.5mm ± 4.2mm. No GPS system failure has been recorded. One coracoid fracture occurred during the first case. Intraoperative navigation system is a reliable and user-friendly technology that allows the surgeon to reach planned glenoid positioning during surgery. Furthermore, this technology will allow the surgeon to compare clinical outcomes to component positioning data. The lack of humeral implant navigation is the main limit of this technique.

Glenoid implant positioning: A new approach using structured light

BackgroundGlenoid implant positioning is an important and challenging step in total shoulder arthroplasty. Accurate glenoid positioning is considered essential to prosthesis longevity and functional outcomes. This paper presents Bullseye, a novel system to ensure accurate glenoid guide pin placement using a hand-held structured light scanner and computer vision algorithms. MethodsPreclinical evaluation of the intra-operative structured light-based Bullseye system was conducted for 10 sawbone and 18 cadaveric procedures. Each scapula was instrumented with a 3.2 mm glenoid guide pin. The Bullseye system was used to determine the position of the guide pin within the scapulae. The accuracy of Bullseye for assessing guide pin start-point and trajectory was validated using CT as a gold standard. ResultsAll procedures were carried out successfully, requiring less than 1 min of intra-operative imaging time. Guide pin start-point was measured to within 0.37±0.28 mm and 0.38±0.32 mm and trajectory to within 0.92±0.40° and 1.27±0.80°, respectively for the sawbone and cadaveric procedures. There was no significant difference in accuracy between the sawbone and cadaveric procedures. No relationships were found between system accuracy and glenoid version or arthritic grade. ConclusionIntra-operative structured light imaging can be used to efficiently and accurately evaluate the 3D position of the glenoid guide pin for total shoulder arthroplasty in-vitro and ex-vivo. Clinical validation is required to determine if use of the Bullseye system improves component positioning outcomes and patient clinical outcomes in the context of a randomized controlled trial. Level of evidenceLevel IV; Case Series

Odd-nosed monkey scapular morphology converges on that of arm-swinging apes

Odd-nosed monkeys ‘arm-swing’ more frequently than other colobines. They are therefore somewhat behaviorally analogous to atelines and apes. Scapular morphology regularly reflects locomotor mode, with both arm-swinging and climbing anthropoids showing similar characteristics, especially a mediolaterally narrow blade and cranially angled spine and glenoid. However, these traits are not expressed uniformly among anthropoids. Therefore, behavioral convergences in the odd-nosed taxa of Nasalis, Pygathrix, and Rhinopithecus with hominoids may not have resulted in similar structural convergences. We therefore used a broad sample of anthropoids to test how closely odd-nosed monkey scapulae resemble those of other arm-swinging primates. We used principal component analyses on size-corrected linear metrics and angles that reflect scapular size and shape in a broad sample of anthropoids. As in previous studies, our first component separated terrestrial and above-branch quadrupeds from clambering and arm-swinging taxa. On this axis, odd-nosed monkeys were closer than other colobines to modern apes and Ateles. All three odd-nosed genera retain glenoid orientations that are more typical of other colobines, but Pygathrix and Rhinopithecus are closer to hominoids than to other Asian colobines in mediolateral blade breadth, spine angle, and glenoid position. This suggests that scapular morphology of Pygathrix may reflect a significant reliance on arm-swinging and that the morphology of Rhinopithecus may reflect more reliance on general climbing. As ‘arm-swinging’ features are also found in taxa that only rarely arm-swing, we hypothesize that these features are also adaptive for scrambling and bridging in larger bodied anthropoids that use the fine-branch component of their arboreal niches.

Does the Orientation of the Glenoid Rim Respect the Scapula Blade Evolving With Age, Compared to the Glenoid Vault Cortex Plane? Impact in Glenoid Positioning in Total Shoulder Arthroplasty

Does the Orientation of the Glenoid Rim Respect the Scapula Blade Evolving With Age, Compared to the Glenoid Vault Cortex Plane? Impact in Glenoid Positioning in Total Shoulder Arthroplasty

Computer navigation of the glenoid component in reverse total shoulder arthroplasty: a clinical trial to evaluate the learning curve

Intraoperative computer navigation has been introduced recently to assist with placement of the glenoid component. The aim of this study was to evaluate the learning curve of a single surgeon performing computer navigation of glenoid implant placement in primary reverse total shoulder arthroplasty (RTSA). Following training with the intraoperative computer navigation system, we conducted a prospective case-series study of the first 24 consecutive patients undergoing a primary RTSA with navigation performed by a single surgeon. Surgical times, complications, and accuracy of glenoid positioning compared with the preoperative plan were evaluated. Surgical times were compared with the preceding non-navigated series of 24 consecutive primary RTSA cases. Postoperative 3-dimensional computed tomography scans were performed to evaluate glenoid component version and inclination compared with the preoperative plan. The total surgical time was 77.3 minutes (standard deviation [SD], 11.8 minutes) in the navigated RTSA cohort and 78.5 minutes (SD, 18.1 minutes) in the non-navigated series. A significant downward trend in the total surgical time was observed in the navigated cohort (P = .038), which flattened after 8 cases. No learning curve was observed in deviation of glenoid version or inclination from the preoperative plan. The mean deviation of achieved version from planned version was 3° (SD, 2°), and the mean deviation of achieved inclination from planned inclination was 5° (SD, 3°). Findings from this study suggest that intraoperative computer navigation will not require substantially increased operating times compared with standard surgical techniques. With prior surgeon training, approximately 8 operative cases are required to achieve proficiency in intraoperative computer navigation of the glenoid component.

Influence of humeral abduction angle on axial rotation and contact area at the glenohumeral joint

Although the elevation angle of the arm affects the range of rotation, it has not been evaluated up to the maximal abduction angle. In this study we conducted an evaluation up to maximal abduction and determined the contact patterns at the glenohumeral (GH) joint. Fourteen healthy volunteers (12 men and 2 women; mean age, 26.9 years) with normal shoulders (14 right and 8 left) were instructed to rotate their shoulders at 0°, 90°, 135°, and maximal abduction for each shoulder at a time. Using 2-dimensional and 3-dimensional single-plane image registration, the internal rotation (IR), external rotation (ER), and range of motion (ROM; ie, axial rotations) at the thoracohumeral (TH) and GH joints, and the contribution ratio (%ROM = GH-ROM/TH-ROM) were calculated for each abduction. The glenoid position with respect to the humeral head was also analyzed. The TH-IR and TH-ER shifted toward an ER with increasing abduction angle, whereas the TH-ROM significantly decreased except at abduction between 0° and 90° (P < .001). The GH-IR and GH-ROM significantly decreased except at abduction between 0° and 90° (P < .001), but the GH-ER remained constant regardless of the abduction. The contribution ratio exceeded 80% for every abduction angle. The glenoid moved on the central and posterior areas of the humeral head at 0° and 90° abduction, respectively, and on the posterosuperior and anterosuperior areas at 135° and maximal abduction, respectively. Our results provide new knowledge about wide axial rotation up to maximal abduction and constant GH-ER at any abduction.

Shoulder patient-specific guide: First experience in 10 patients indicates room for improvement.

Implantation of the glenoid component of a total shoulder prosthesis can be facilitated by using a patient-specific guide (PSG) designed to ensure replication of the preoperatively planned position. The objective of this study was to assess the reliability and accuracy of a PSG in replicating the planned glenoid component position during total shoulder arthroplasty (TSA). Additional criteria should be used for 3D preoperative planning and PSG design to further improve the accuracy of glenoid component positioning. We studied 10 patients who underwent TSA with use of a PSG to position the glenoid component after preoperative 3D planning. Postoperative glenoid version and tilt were measured and compared to the planned values. We also used new criteria to assess implant rotation and global 3D position, as well as accuracy of the 3D pilot hole for the glenoid guide-pin. Mean errors in glenoid position were -1.7°±4.4° for version, -0.4°±4.9° for tilt, and 6.0°±13.5° for rotation. Mean difference in global orientation of the glenoid implant versus the planned value was 4.9°±2.5°. Mean 3D discrepancy in glenoid pilot hole position was 2.9±0.5mm; the discrepancy was greater in the mediolateral direction (1.9±0.9mm) than in the supero-inferior (1.1±1.2mm) and antero-posterior (0.8±1.2mm) directions. The poor performance of the PSG in controlling rotation and reaming may explain the difference in global glenoid position compared to the planned value. Improvements in PSG design to incorporate these two parameters deserve consideration. II, prospective cohort study.

Short, Medium and Long Term Complications After Total Anatomical Shoulder Arthroplasty.

Total shoulder arthroplasty (TSA) is an effective approach for the treatment of a variety of clinical conditions affecting the shoulder, including osteoarthritis, inflammatory arthritis and osteonecrosis, and the number of TSA implanted has grown exponentially over the past decade. This review gives an update of the major complications, mainly infections, instability and loosening, encountered after TSA, based on a corpus of recent publications and a dynamic approach: The review focuses on the causes of glenoid loosening, which account for 80% of the complication, and underlines the importance of glenoid positioning in the recovery of early shouder function and in the long term survival rate of TSA.

Three-Dimensional Templating and Use of Standard Instrumentation in Primary Anatomic Total Shoulder Arthroplasty.

Three-dimensional (3D) templating of the glenoid in anatomic shoulder arthroplasty allows for more accurate planning and more optimal positioning of the glenoid component than 2-dimensional computed tomography (2D CT) scans through an improved understanding of both the pathologic and the premorbid glenoid joint line, version, and inclination in reference to an idealized calculated glenoid position. Obtain a CT scan of the entire scapula and proximal part of the humerus with slices of ≤1 mm and a 3D reconstruction with subtraction of the humeral head, and identify the scapular and glenoid planes to define the pathologic version and inclination, which can be done in any commercially available software program while following these basic principles (Video 1). Carefully evaluate for the presence of the native glenoid, noting its version and inclination, and be careful to distinguish the true native glenoid from osteophytes (Video 2). Place the virtual glenoid component to restore the premorbid glenoid anatomy (Video 3). In the presence of bone loss from posterior glenoid wear, assess the need for an augmented glenoid component, bone graft, or eccentric reaming to achieve adequate backside seating (Video 4). Once the glenoid component has been templated, note the starting location and trajectory of the center pin used for cannulated glenoid reaming and bone preparation (Video 5). Intraoperatively, remove remaining labrum and any remaining cartilage or soft tissue, and expose the glenoid periphery to clearly define the osseous anatomy, including the base of the coracoid, such that it mirrors what the 3D CT scan and preoperative plan display (Video 6). Place the center pin for glenoid preparation in the previously templated location and trajectory to emulate the surgical plan defined in the software (Video 7). We performed a prospective, randomized controlled trial of positioning of the glenoid component in anatomic TSA using preoperative planning with 3D CT scans and standard instrumentation compared with using 3D CT preoperative planning with patient-specific instrumentation29.

Patient-specific instrumentation for total shoulder arthroplasty: not as accurate as it would seem

There is an increasing body of literature suggesting that the use of patient-specific instrumentation (PSI) in total shoulder arthroplasty (TSA) results in improved positioning of the glenoid component. The aim of this in vivo study was to assess the accuracy of PSI of the glenoid component in TSA in a consecutive series at a single center. Eleven consecutive TSAs (7 TSAs and 4 reverse TSAs) were performed using custom-made patient-specific positioning guides for the glenoid component. Each patient had preoperative computed tomography scans and guides produced to allow 0° of glenoid inclination and version in anatomic TSAs and 10° of inferior inclination for reverse TSAs. Postoperative computed tomography imaging was performed to determine accuracy of component implantation. Patients were observed to the 1-year mark. For the conventional TSA group, the mean version was measured at 8° ± 10° retroversion and 1° ± 4° inclination. For reverse TSAs, mean version was 10° ± 10° retroversion and -1° ± 5° inclination. There were 5 cases classified as outliers in terms of version (>10° anteversion or retroversion). We had a mean correction of version of 22° ± 9° and 17° ± 9° in inclination compared with preoperative measurements. Our results suggest that the in vivo accuracy of PSI-guided glenoid positioning is not as successful as suggested in the literature.