Clinical and radiographic results of eccentric glenoid reaming in reverse total shoulder arthroplasty

BackgroundOne option for treating glenoid bone loss in reverse shoulder arthroplasty (RSA) is eccentric reaming of the glenoid, but the effect on clinical results is unclear. The aim of this study was to investigate the association between medialization of the bone-baseplate interface (herein, ‘medialization’) caused by eccentric reaming of the glenoid and scapular notching, baseplate loosening, and clinical outcomes after RSA.MethodsWe retrospectively reviewed data for 91 patients who underwent primary RSA between January 2014 and December 2016 with a lateralized implant and a minimum 2-year follow-up. The amount of medialization was estimated using a 3-dimensional computed tomography scan-based computer planning software. The average amount of medialization estimated by the 3-dimensional planning software was 3.4 mm (range, 0.5-10 mm). Outcomes included range of motion (ROM), American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST) score, visual analog scale (VAS) for pain, and the rates of scapular notching and baseplate loosening. The association between the estimated medialization and the outcomes of interest was evaluated using multivariate models.ResultsAfter controlling for age, sex, diagnosis, subscapularis repair, glenosphere size, and baseline ROM, medialization was not associated with the postoperative abduction (P = .35), external rotation (ER) at 90° (P = .16), internal rotation at 90° (P = .08), and internal rotation at the back (P = .06). However, we found a significant association between medialization and postoperative ER at the side (P = .02). According to the multivariate model, for a 1-mm increase in medialization during surgery, a decrease of 1.6° in postoperative ER would be expected. We found no association between medialization and the postoperative ASES score (P = .48), SST score (P = .59), or VAS score (P = .27). At a minimum of 2 years of follow-up, we found no baseplate loosening or radiographic signs of baseplate loosening in any patient. Scapular notching of grades 1 to 2 was observed in 22 patients (24%). We were not able to detect a difference in scapular notching when medialization was > 1 mm ver when medialization ≤ 1 mm (odds ratio, 2.5; 95% confidence interval: 0.28-23).ConclusionsIncreasing medialization due to eccentric reaming after RSA with a lateralized implant was associated with a decrease in postoperative ER at the side. However, increasing medialization was not associated with worse patient-reported outcome scores or increased baseplate loosening at short-term follow-up.     

Reverse total shoulder arthroplasty in wheelchair-dependent patients: a matched cohort study

BackgroundShoulder function in wheelchair-dependent patients is critical for preserving independence and quality of life due to lower extremity impairment. The purpose of this study was to report the revision rate, as well as clinical and radiological outcome in wheelchair-dependent patients treated with reverse total shoulder arthroplasty (RTSA) and to compare them to an ambulating population.MethodsProspectively obtained data of 21 primary RTSAs in 17 wheelchair-dependent patients (5 male, 12 female) with a median age of 72.4 years (range: 49-80) and a minimum follow-up of 2 years were analyzed retrospectively. Revision rate, clinical (Subjective Shoulder Value = SSV, relative Constant-Murley Score = rCS, wheelchair user’s shoulder pain index = WUSPI) and radiological (glenoid loosening, scapular notching, glenoid inclination) outcome, as well as implant-related parameters (baseplate peg length, glenosphere size, bony augmentation), were compared with a 2:1 matching cohort of 42 ambulating patients (10 male, 32 female) with a median age of 72.5 years (range: 56-78).ResultsThe revision rate was 9.5% in both cohorts. In the wheelchair cohort, two shoulders had to be revised due to a complete baseplate dislocation. In the matching cohort, four shoulders had to be revised due to one prosthetic dislocation, one traumatic and one atraumatic scapular spine fracture with glenoid baseplate dislocation, and one fracture of the greater tuberosity. Median preoperative SSV and rCS did not differ significantly between cohorts. Postoperative SSV was also comparable (wheelchair: median 70 (range: 10-99) vs. matching: median 70 (30-100), p = n.s.). Relative CS was significantly lower in the wheelchair cohort (65% vs. 81.4%, P = .004). Median postoperative WUSPI was 35 points (range: 13-40) for difficulty and 0 points for pain (range: 0-29). The highest difficulty and pain were found for ‘hygiene behind the back’ and ‘propulsion of wheelchair up a ramp or on uneven surface’. Glenoid loosening, scapular notching, and postoperative baseplate inclination did not differ significantly between cohorts. In the wheelchair cohort, glenoid autograft augmentation (38.1% vs. 7.1%, P = .002) and implantation of baseplates with longer pegs were performed more often (≥ 25mm: 38.1% vs. 7.1%, P = .004).ConclusionRTSA is a valuable therapeutic option for the treatment of advanced OA or irreparable rotator cuff tears in wheelchair-bound patients with high patient satisfaction. Postoperatively, poorer function and a higher rate of baseplate dislocations might be anticipated compared to ambulating patients.     

Computed tomography–based three-dimensional modeling of glenoid bone preservation with augmented baseplates

BackgroundReverse total shoulder arthroplasty (rTSA) is a treatment option for a variety of shoulder pathologies, including rotator cuff arthropathy, glenohumeral arthritis, and irreparable rotator cuff tears and fractures. There has been substantial improvement in rTSA implants and surgical techniques, such as augmented baseplates that preserve bone tissue. In this study, we used three-dimensional modeling to determine the extent of bone preservation with augmented baseplates in rTSA.MethodsComputed tomography scans from 50 consecutive patients before they underwent rTSA were used to create three-dimensional models of each glenoid. The virtual positions of reverse shoulder baseplate implants followed strict parameters for adequate fixation as determined through consensus among 4 fellowship-trained shoulder specialists. Parameters for adequate fixations included 100% backside contact, neutral scapular version, and 10° of inferior tilt. The 4 baseplate options trialed on each glenoid were a nonaugmented baseplate, a small 10° half-wedge augment, a medium 20° half-wedge augment, and a large 30° half-wedge augment. The extent of volumetric glenoid bone removal and lateralization of the baseplate was calculated for each scenario.ResultsPreoperative computed tomography imaging showed a mean of 10.7° of retroversion and a reverse shoulder arthroplasty angle of 21.3°. A medium augment (20° half wedge) was determined as optimal in 29 cases, and a large augment (30° half wedge) was considered optimal for the remaining 21 cases. The use of augmented baseplates was calculated to preserve 54% glenoid bone stock (1989 ± 650 mm³ bone removal vs. 4439 ± 1636 mm³ with nonaugmented baseplate; P < .001). The surgeon-selected augmented baseplate was on average 4.1 mm lateral in comparison to the nonaugmented baseplate.ConclusionsThe use of augmented baseplates reduces the volume of bone that needs to be removed in rTSA. Furthermore, augmented baseplates result in relative lateralization of the glenosphere, which has been theorized to improve soft tissue tension and limit impingement and scapular notching. Further exploration of the impact of augmented baseplates on clinical outcomes is needed.     

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     

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     

Scapular notching in reverse shoulder arthroplasty

The causes and consequences of scapular notching after reverse shoulder arthroplasty (RSA) were investigated in 326 consecutive patients (337 shoulders) undergoing RSA between 1991 and 2003. Patients underwent 269 (80%) primary RSAs and 68 revisions of unconstrained shoulder prosthesis. At last follow-up (average, 47 months; range, 24-120 months) 62% had scapular notching. Notching frequency and extension were correlated to the length of follow-up (P = .0005). Notching was more frequent in cuff tear arthropathy (P = .0004), grade 3 or 4 fatty infiltration of the infraspinatus (P = .01), and narrowed acromiohumeral distance (P < .0001). Glenoids preoperatively oriented superiorly were more at risk for notching (P = .006). More notching occurred when the RSA was implanted using an anterosuperior approach vs a deltopectoral approach (P < .0001). Notching was correlated with humeral radiolucencies in proximal zones (P < .0001) and with glenoid radiolucent lines (P < .0001). Positioning of the baseplate definitely influences scapular notching. High positioning of the baseplate and superior tilting must be avoided.     

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     

Decreased scapular notching with lateralization and inferior baseplate placement in reverse shoulder arthroplasty with high humeral inclination

Background:

Scapular notching is a radiographic finding of unknown clinical significance following reverse total shoulder arthroplasty (RTSA). The purpose of this study was to determine how baseplate position affects the incidence of scapular notching and measure the clinical outcomes.

Hypothesis:

We hypothesized that low base plate position on the glenoid and new prosthesis design with a higher humeral inclination angle would decrease the incidence of notching at 2 years follow-up.

Materials and methods:

A total of 54 patients with an average follow-up of 30 months met inclusion criteria and underwent radiographic analysis of scapular notching and radiographic measures to determine glenoid component placement. Clinical measures including visual analog score, American Shoulder and Elbow Surgeons (ASES) scores, and range of motion (ROM) were prospectively collected.

Results:

Thirty-nine of the 54 patients had no notching. 7 had Grade 1 notching, 7 had Grade 2 notching, one had Grade 3, and one had Grade 4 notching. Notching was associated with higher placement of the glenoid component as measured by peg-glenoid rim distance and base plate distance. All patients with no evidence of notching at 1-year, continued to have no notching after multi-year follow-up. Clinical outcome measures including ASES scores, ROM, and visual analog pain scores were improved at follow-up.

Conclusion:

We concluded that lower neck-shaft angle and low baseplate positioning led to a low incidence of significant scapular notching as only 6 out of 57 (16%) patients had notching Grade 2 and above. At short-term follow-up, this RTSA results in excellent clinical outcomes and a significantly lower scapular notching rate than traditional techniques.     

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     

Reverse shoulder arthroplasty with metallic augments to preserve bone and restore joint line in patients with glenoid bone loss

BackgroundGlenoid bone loss poses significant challenges for reverse shoulder arthroplasty. In these patients, excess reaming can lead to further bone loss and medialization of the joint line. Metallic augments have been described as a technique for addressing this issue. However, there are currently no studies evaluating the effect of metallic augments on anatomic outcomes. This study evaluates the effect of metallic augments on the glenohumeral joint line and bone preservation. We hypothesize that metallic augments can preserve bone while preventing further medialization of the joint line in patients with preoperative glenoid bone loss.MethodsA prospective single-center, 2-surgeon consecutive case series was evaluated with postoperative computed tomography scans. Three-dimensional reconstruction was used to create models of the scapula and humerus. Comparisons were made with preoperative computed tomography scans using volumetric analysis to evaluate bone loss. The base of the coracoid was used as a constant landmark to assess the joint line position and, by proxy, the center of rotation. Further evaluation of the glenoid version and inclination was measured on the reconstructed models through standardized techniques.ResultsFifteen patients (16 implants) underwent preoperative planning and reverse shoulder arthroplasty with metallic augments from January 1, 2018, to January 1, 2021. The mean follow-up time was 13.1 months. Analysis revealed that augments prevented further medialization of the joint line and corrected the deficit on average by 10.2 mm (range 6.9-14.3; standard deviation 2.0). The mean bone volume removed during surgery was 1292 mm³ (range 525-2256; standard deviation 527), with this value inclusive of the baseplate post volume (～800 mm³). Inclination and version were restored to acceptable limits in all cases.ConclusionsReverse shoulder arthroplasty with metallic augments reliably preserves bone and prevents medialization of the joint line in patients with preoperative glenoid bone loss. Further research is required to assess the long-term and functional outcomes of this technique.     

A randomized prospective study comparing migration of hydroxyapatite and non-hydroxyapatite coated glenoid components using radiostereometric analysis

BackgroundPrimary shoulder arthroplasty can significantly improve quality of life; however, the glenoid baseplate remains the most common component to loosen, which may result in implant failure and subsequent revision surgery. Radiostereometric analysis (RSA) is considered the gold standard for accurate measurement of micro-motion between implant and bone. The aims of this study were to compare migration of the Lima SMR porous titanium hydroxyapatite (HA) coated and non-hydroxyapatite (non-HA) coated glenoid components through a prospective, randomized 2-arm trial using RSA, whilst also comparing clinical and functional outcomes.MethodsTwenty patients were randomized into 2 equal (HA and non-HA coated) groups with all patients undergoing primary anatomic shoulder arthroplasty, at which time tantalum beads were also inserted. RSA imaging was performed immediately postoperatively, then at 3, 6, 12, and 24 months postprocedure. These images were digitized and analyzed using model-based RSA software. All patients completed Oxford Shoulder Score (OSS), American Shoulder and Elbow Surgeons (ASES) score, Constant Score (CS) and Visual Analogue Scale (VAS) pain scores pre-and postoperatively at the aforementioned time points. Unpaired t-tests were used for clinical outcome data; Mann-Whitney U tests were used for RSA data. Significance levels were set at P < .05.ResultsMean age for the HA group was 72.3 years; 69.5 years for the non-HA group. Mean follow-up for both groups was above 36 months. No significant differences in glenoid migration were observed at each of the postoperative time points; the only exception being at 12 months (non-HA group displaying significantly greater rotation in the z-axis). The HA group displayed fractionally more translation in the x- and z-axes at all time points (not significant). Rotation in the z-axis was marginally greater at all postoperative time points in the non-HA group. Median total migration values revealed greater motion for the non-HA group at 3, 6, and 12 months (not significant). All clinical outcome measures improved significantly within each group; no statistical differences were observed between the groups for any outcome measure. One patient in each group underwent revision surgery to reverse shoulder arthroplasty due to unexplained pain (HA group) and cuff failure (non-HA group) only. Radiolucent lines were noted in 2 patients who are still under follow-up.ConclusionThis study has revealed promising early results of both HA coated and non-HA coated implants, however, hydroxyapatite coating of glenoid components does not significantly improve outcome scores nor provide extra stability compared to non-hydroxyapatite coated implants at 2 years postprocedure.Level of evidenceLevel II; Randomized Controlled Trial     

Onlay versus inlay reverse total shoulder arthroplasty: a retrospective comparison of radiographic and clinical outcomes

IntroductionRecent innovations in reverse shoulder arthroplasty (RSA) have presented 2 distinct humeral stem designs: an onlay system that rests above the anatomic neck and an inlay component that rests within the metaphysis. The purpose of this study is to compare clinical and radiographic outcomes between inlay and onlay-designed humeral stems in lateral center of rotation RSA implant systems.MethodsA retrospective cohort study was performed on primary RSA patients treated by 2 surgeons at 2 separate hospitals with a minimum 2-year follow-up. Patients were categorized based on treatment with an onlay or inlay humeral design and matched 1:1 by indication and age. Patient-reported outcome measures (PROMs), including the Simple Shoulder Test, American Shoulder and Elbow Surgeons, and Visual Analog Score for pain, as well as active motion (forward elevation, internal rotation) were recorded at pre- and postoperative intervals. An Inlay-Onlay index assessed the degree of inset or offset of each particular implant referencing the anatomic neck. Radiographic analysis focused on scapular notching, bone resorption around the humeral stem, and acromion stress fractures.ResultsA total of 92 patients participated in the 1:1 matched analysis (46 each group). Cohorts were similar in age, gender, indication, follow-up length, and preoperative PROMs, with the exception of Simple Shoulder Test. At the most recent follow-up, there were no differences in all PROMs between groups. There were no differences in active internal rotation, but patients with an onlay-configuration demonstrated greater external rotation (P< .001) and forward flexion (P< .001). Greater tuberosity and calcar resorption occurred in 34 (74%) and 18 (39%) patients with an onlay-designed prosthesis, compared to 13 (28%) and 1 (2%) in the inlay group, respectively (P< .0001). Both groups had low rates of scapular notching (P= 1.0), while acromial fractures occurred in 6 patients with an onlay stem and in 4 patients with the inlay stem (P= .73).ConclusionThere were no differences in clinical outcomes or incidence of acromial fractures following RSA with an onlay- or inlay-style humeral stem prosthesis. Bone resorption of the proximal humerus occurred more frequently in patients with an onlay prosthesis, suggesting that an inlay prosthesis may afford better prevention of humeral stress shielding.Level Of EvidenceLevel III; Retrospective Comparative Study     

Comparison of radiographs and computed tomography (CT) imaging for preoperative evaluation and planning for shoulder arthroplasty

BackgroundThe purpose of this study was to determine if addition of CT to axillary radiographs (AXR) alters preoperative decision making for shoulder arthroplasty.MethodsPreoperative deidentified images (XR alone and XR with CT) of 50 patients with glenohumeral arthritis were reviewed independently by 3 reviewers in a blinded fashion. Each reviewer graded images for glenoid wear pattern as simple (Walch A1 or B1) or advanced [A2, B2, C]), adequacy of AXR and need for advanced imaging. The reviewers determined a preoperative plan for all patients based on XR alone vs. XR and CT including the arthroplasty type (anatomic or reverse total shoulder) and their plan for treating glenoid wear (eccentric or standard reaming vs. bone graft or augment). Kappa values (κ) were calculated to determine inter-rater agreement and consistency among multiple reviewers. Fisher's exact test was used to assess any difference in preoperative plan once the shoulders were separated into simple and advanced glenoid wear patterns.ResultsThe 3 reviewers agreed that quality of AXRs was significantly inadequate (P < .001) for assessing glenoid wear in advanced glenoid wear patterns compared to simple wear patterns. Following evaluation on AXRs alone, the need for CT imaging was significantly higher in advanced glenoid wear patterns compare to simple ones (81% vs. 31%; P < .001). The addition of CT images did not result in a significant change to the preoperative plan in simple glenoid wear patterns but in advanced glenoid wear, addition of CT can change the preoperative plan with respect to arthroplasty type and/or strategy for addressing glenoid wear.ConclusionAxillary radiographs are often inadequate for preoperative planning in shoulder arthritis with advanced glenoid wear patterns (Walch A2, B2, C types). Addition of CT imaging to radiographs in shoulder arthritis with advanced glenoid wear can affect the preoperative decision with respect to type of shoulder arthroplasty and/or plan for addressing glenoid wear (reaming, bone graft or augmented glenoids).Level of evidenceLevel IV     

Optimizing glenosphere position and fixation in reverse shoulder arthroplasty, Part Two: The three-column concept

Scapular geometry is complex, and a screw-placement technique for optimizing glenoid component fixation with an Aequalis Reversed Shoulder Prosthesis (Tornier, Inc., Edina, MN) has not yet been described. Ten cadaveric human scapulae were implanted with 2 types of reverse arthroplasty baseplates, 1 with fixed-angle locking screw holes and 1 with multidirectional locking screw holes. Optimal screw placement was defined as that which maximized screw length, accomplished far cortical fixation, and attained screw purchase in good bone stock. An anterior cruciate ligament drill guide was used to find the ideal trajectory for each screw. Trajectory angles of the screws relative to the face of the baseplate are presented for what we believe is best possible fixation. Awareness of the 3 major columns of scapular bone (the base of coracoid, the spine, and the pillar) and utilization of a baseplate with variable-angle locking screws will allow optimal initial fixation of the glenosphere.     

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.     

Clinical outcomes of shoulder arthroplasty for post-instability arthropathy after open anterior bone block stabilization

BackgroundPost-instability glenohumeral arthropathy can occur after nonanatomic instability repairs. With advanced secondary arthritis, subsequent shoulder arthroplasty may be complicated by altered surgical anatomy, poor range of motion, subscapularis deficiency, unique glenoid wear patterns, and/or aberrant neurovascular anatomy. The purpose of this study was to evaluate the clinical outcomes of patients undergoing shoulder arthroplasty after previous open nonanatomic anterior shoulder stabilization, particularly glenoid bone block procedures.MethodsBetween 2008 and 2014, all patients with shoulder arthroplasty for symptomatic post-instability glenohumeral arthropathy after prior open stabilizations were identified from surgical case logs of two senior shoulder surgeons. Demographic variables were extracted from electronic medical records, operative reports, and preoperative and postoperative radiographs, and a minimum 24-month follow-up with completion of patient-reported questionnaires was required. Postoperative active forward elevation and active external rotation were recorded. The primary outcome measures were the visual analog scale for pain, American Shoulder and Elbow Surgeons Shoulder score, and the Simple Shoulder Test. Perioperative complications and rates of secondary reoperation were extracted.ResultsA total of 12 patients were identified with an average age of 63 ± 12 years (range, 46-83), including 7 males and 5 females, and index surgery included open Bristow (n = 7), open Latarjet (n = 2), iliac crest bone graft (n = 1), and Putti-Platt procedure (n = 2). Seven patients underwent anatomic TSA, 4 reverse TSA, and 1 hemiarthroplasty. At an average of 44 ± 21 months follow-up, average active forward elevation and active external rotation improved from 100 ± 36 preoperatively to 132 ± 41 (P = .12) postoperatively and 19 ± 15 to 49 ± 11 (P < .01), respectively. The average visual analog scale decreased from 5 ± 3 to 1 ± 2 (P < .01) and mean American Shoulder and Elbow Surgeons improved from 44 ± 23 to 79 ± 17 (P < .01); and the average Simple Shoulder Test improved from 4 ± 2 to 9 ± 3 (P < .01). No perioperative complications or secondary reoperations were required, and only one patient experienced subsequent instability due to subsequent shoulder trauma.ConclusionDespite the surgical complexity and unique challenges associated with post-instability arthropathy, shoulder arthroplasty after prior open anterior bone block procedure or nonanatomic reconstruction is a safe procedure with low risk of perioperative complication, subsequent shoulder instability, or secondary revision surgery. All patients experienced significant improvements in pain, range of motion, and self-reported function at short- to mid-term follow-up.     

Stemless and stemmed total shoulder arthroplasty: a comparison of short-term clinical and radiographic outcomes

BackgroundStemless total shoulder arthroplasty could provide benefits over stemmed arthroplasty which has represented the gold standard for decades. Proposed benefits of stemless arthroplasty include better reproduction of anatomy and reduction in stress shielding; however, this does not appear to be confirmed by any study. The hypothesis was there would be no clinical differences between the stemless and the short-stem prosthesis, but the stemless prosthesis would better reproduce coronal radiographic anatomy and have less radiographic evidence of stress shielding.Materials and MethodsA prospectively collected data of patients undergoing primary, anatomic total shoulder arthroplasty for osteoarthritis were retrospectively reviewed. Patient-determined outcomes including the Western Ontario Osteoarthritis Index, American Shoulder and Elbow Surgeons score, Single Assessment Numeric Evaluation, Simple Shoulder Test, and Shoulder Activity Level were recorded preoperatively, at 1 year, and at 2 years. Preoperative and 1-year postoperative range of motion was recorded. Radiographic parameters to assess restoration of proximal humeral anatomy included humeral head height, humeral neck angle, humeral centering on the glenoid, and postoperative restoration of the anatomic center of rotation. Final postoperative radiographs were assessed for evidence of stress shielding.ResultsForty-eight patients had a stemmed humeral prosthesis, and 109 patients had a stemless prosthesis. Patient-determined outcomes were available from 2 years postoperatively in 99.4%. Both groups had significant improvements in all patient-reported outcomes and range-of-motion metrics, but there were no differences between the stemless and stemmed groups in these outcomes. The prosthetic humeral head of the stemmed components was more likely to extend further superior to the humeral osseous margin than that of the stemless group (2.0 ± 2.4 vs. 0.8 ± 1.4 mm; P = .0004). The stemless group had a smaller postoperative deviation from the anatomic center of rotation than the stemmed group (2.5 ± 1.9 vs. 3.2 ± 2.1 mm; P = .04). The humeral neck angle was comparable between the stemmed group and the stemless group (133 ± 7° vs. 131 ± 8°; P = .06). There was similar mean deviation of humeral head centering on the glenoid prosthesis between the stemmed and stemless groups (1.9 ± 1.8 vs. 1.6 ± 1.7 mm; P = .20). There was evidence of stress shielding in 10 patients (21%) with a stemmed prosthesis and in no patients with a stemless prosthesis at 1-year follow-up (P < .0001).ConclusionsThere were no differences in patient-determined outcomes between the groups at 2-year follow-up. Restoration of proximal humeral anatomy was either better or equivalent with the stemless prosthesis compared to the stemmed one. Radiographic evidence of stress shielding was found in the stemmed prosthesis but not in the stemless prosthesis at 1-year follow-up.     

The polyethylene on bone articulation,as occurs with scapular notching,is associated with osteolytic potential

IntroductionScapular notching is a common finding following reverse total shoulder arthroplasty. Severe notching can extend beyond the inferior baseplate screw or post and is therefore unlikely to be the result of isolated mechanical impingement. It is highly likely that the cause of this bone loss is biologically mediated osteolysis, but the driver of this osteolysis is unknown. We completed in vitro polyethylene on bone wear testing, as occurs with scapular notching, to characterize the osteolytic potential of this articulation.MethodsPhysiologically relevant wear testing was performed with 18 polyethylene pins articulating against cortical bone, cancellous bone, and cobalt-chrome pucks. Pins were cycled up to 1,000,000 times, or until failure, and incremental material loss was determined to calculate polyethylene and bone wear rates. Polyethylene particles were extracted from the associated lubricant and evaluated using scanning electron microscopy. To validate the model, wear patterns on polyethylene pins were compared to those on 24 explanted reverse prostheses.ResultsPolyethylene wear rates were significantly higher on cortical bone (3.5-times, P = .040) and cancellous bone (10,700-times, P = .015) than on cobalt-chrome. Cortical bone wear rates decreased over time (P = .003). Electron microscopy demonstrated that polyethylene on cortical and cancellous bone both produced submicron polyethylene particles, the size necessary to induce biologically mediated osteolysis. Analysis of explanted reverse polyethylene components with impingement demonstrated similar wear patterns to what was seen in vitro.ConclusionThe polyethylene on bone articulation, as occurs with scapula notching, has potential to be an osteolytic driver as it is marked by high polyethylene wear rates and produces particles small enough to cause macrophage-mediated osteolysis, as has been demonstrated following total hip arthroplasty.Level of evidenceBasic Science Study     

Scapular body fractures: Short-term results of surgical management with extended indications

IntroductionScapular body fractures represent less than 1% of all skeletal fractures. Operative criteria and risk factors for scapular fracture instability are well defined. Non-operative management of scapular body fractures show satisfactory results but with shortening and medialization of the scapular body. The aim of this study is to evaluate if surgical treatment will result in an improved quality of life and shoulder function compared to non-operative treatment on patients suffering from a scapular body fracture.Materials and MethodsFrom a total of 381 retrospectively identified scapular body fractures, we included 45 patients. The enrolled patients were divided into two groups: the surgical treatment (ST, n = 20) group and the non-operative treatment (NOT, n = 25) group. The Non-Union Scoring System (NUSS) was used to assess bone healing on radiographs. The functional evaluation of the two groups during the follow-up were performed using the Constant Shoulder Score (CSS) and the Quick Disabilities of the Arm, Shoulder and Hand Score (QuickDASH). Complications, reoperation rates, and time until bony union were also documented. The minimum follow-up for this study was designated as 12 months.ResultsThe ST group had better mean CSS and QuickDASH scores compared to the NOT group at 1, 3 and 6 months of follow-up. No statistically significant difference was detected at 12 months follow-up. ST group also demonstrated improved results in time until bone union, reduction of rehabilitation time, complications and return to work rates.ConclusionThis study suggests that surgical treatment for extraarticular scapular fractures can achieve better short-term functional outcomes (3 to 6 months) compared to conservative treatment.     

Glenoid baseplate fixation using hybrid configurations of locked and unlocked peripheral screws

Background

The use of peripheral locked screws has reduced glenoid baseplate failure rates in reverse shoulder arthroplasty. However, situations may arise when one or more non-locked screws may be preferred. We aimed to determine if different combinations of locked and non-locked screws significantly alter acute glenoid baseplate fixation in a laboratory setting.

Materials and methods

Twenty-eight polyurethane trabecular bone surrogates were instrumented with a center screw-type glenoid baseplate and fixated with various combinations of peripheral locked and non-locked screws (1-, 2-, 3- and 4-locked con). Each construct was tested through a 55° arc of abduction motion generating compressive and shear forces across the glenosphere. Baseplate micromotion (μm) was recorded throughout 10,000 cycles for each model.

Results

All constructs survived 10,000 cycles of loading without catastrophic failure. One test construct in the 1-locked fixation group exhibited a measured micromotion >150 μm (177.6 μm). At baseline (p > 0.662) and following 10,000 cycles (p > 0.665), no differences were observed in baseplate micromotion for screw combinations that included one, two, three and four peripheral locked screws. The maximum difference in measured micromotion between the extremes of groups (1-locked and 4-locked) was 29 µm.

Conclusions

Hybrid peripheral screw fixation using combinations of locked and non-locked screws provides secure glenoid baseplate fixation using a polyurethane bone substitute model. Using a glenosphere with a 10-mm lateralized center of rotation, hybrid baseplate fixation maintains micromotion below the necessary threshold for bony ingrowth.

Level of Evidence

N/A/, basic science investigation.