Posterior Decentering Research Articles

Differences in Osseous Shoulder Morphology, Scapulothoracic Orientation, and Muscle Volume in Patients With Constitutional Static Posterior Shoulder Instability (Type C1) Compared With Healthy Controls

Background: Constitutional static posterior humeral decentering (type C1 according to ABC Classification) has been recognized as a pre–osteoarthritic deformity that may lead to early-onset posterior decentering osteoarthritis at a young age. Therefore, it is important to identify possible associations of this pathologic shoulder condition to find more effective treatment options. Purpose: To perform a comprehensive analysis of all parameters reported to be associated with a C1 shoulder—including the osseous shoulder morphology, scapulothoracic orientation, and the muscle volume of the shoulder girdle in a single patient cohort. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A retrospective, comparative study was conducted analyzing 17 C1 shoulders in 10 patients who underwent magnetic resonance imaging (MRI) with the complete depiction of the trunk from the base of the skull to the iliac crest, including both humeri. The mean age of the patients was 33.5 years, and all patients were men. To measure and compare the osseous shoulder morphology (glenoid version, glenoid offset, humeral torsion, anterior acromial coverage, posterior acromial coverage, posterior acromial height, and posterior acromial tilt) and scapulothoracic orientation (scapular protraction, scapular internal rotation, scapular upward rotation, scapular translation, scapular tilt, and thoracic kyphosis), these patients were matched 1 to 4 according their age, sex, and affected side with shoulder-healthy patients who had received positron emission tomography (PET)-computed tomography. To measure and compare the muscle volume of the shoulder girdle (subscapularis, infraspinatus/teres minor, supraspinatus, trapezius, deltoid, latissimus dorsi/teres major, pectoralis major, and pectoralis minor), patients were matched 1 to 2 with patients who had received PET-MRI. Patients with visible pathologies of the upper extremities were excluded. Results: The C1 group had a significantly higher glenoid retroversion, increased anterior glenoid offset, reduced humeral retrotorsion, increased anterior acromial coverage, reduced posterior acromial coverage, increased posterior acromial height, and increased posterior acromial tilt compared with controls (P < .05). Decreased humeral retrotorsion showed significant correlation with higher glenoid retroversion (r = −0.742; P < .001) and higher anterior glenoid offset (r = −0.757; P < .001). Significant differences were found regarding less scapular upward rotation, less scapular tilt, and less thoracic kyphosis in the C1 group (P < .05). The muscle volume of the trapezius and deltoid was significantly higher in the C1 group (P < .05). Conclusion: Patients with C1 shoulders differ from healthy controls regarding osseous scapular and humeral morphology, scapulothoracic orientation, and shoulder girdle muscle distribution. These differences may be crucial in understanding the delicate balance of glenohumeral centering.

Preoperative Shoulder MRI Findings to Predict Subscapularis Tendon Tear Requiring Surgical Repair.

This study aimed to investigate which indirect parameters on preoperative MRI were the principal predictors of subscapularis tendon tears (STTs) requiring surgical repair. Preoperative MRI scans of 86 patients were retrospectively reviewed for visual assessment of the STT, pathology of the long head of the biceps tendon (LHBT), posterior decentering (PD) of the humeral head, humeral rotation, fatty degeneration, and subscapularis muscle atrophy. To evaluate atrophy, visual grading using the anatomical line connecting the coracoid tip to the glenoid base, designated as the base-to-tip line (BTL), and thickness measurements were performed in the en-face view. Arthroscopically, 31 patients (36%) exhibited Lafosse type III or IV STT and underwent surgical repair. LHBT pathology (p = 0.002), PD of the humeral head (p = 0.012), fatty degeneration (p < 0.001), and BTL grade (p = 0.003) significantly correlated with STT. In the multivariate analysis, PD of the humeral head (p = 0.011, odds ratio [OR] = 5.14) and fatty degeneration (p = 0.046, OR = 2.81) were independent predictors of STT. PD of the humeral head and fatty degeneration of the subscapularis can help to diagnose clinically significant STT. Interpretation of these findings may contribute to the planning of an optimal surgical strategy.

Risk Factors for Stiffness Requiring Intervention After Ream-and-Run Arthroplasty.

We conducted a retrospective review of our shoulder arthroplasty database to identify patients who underwent ream-and-run arthroplasty and determined which patients underwent subsequent repeat procedures (MUA and/or open revision) indicated for postoperative stiffness. The minimum follow-up was 2 years. We collected baseline demographic information and preoperative and 2-year patient-reported outcome scores and analyzed preoperative radiographs. Univariate and multivariate analyses determined the factors significantly associated with repeat procedures to treat postoperative stiffness. There were 340 patients who underwent ream-and-run arthroplasty. The mean Simple Shoulder Test (SST) scores for all patients improved from 5.0 ± 2.4 preoperatively to 10.2 ± 2.6 postoperatively (p < 0.001). Twenty-six patients (7.6%) underwent open revision for stiffness. An additional 35 patients (10.3%) underwent MUA. Univariate analysis found younger age (p = 0.001), female sex (p = 0.034), lower American Society of Anesthesiologists (ASA) class (p = 0.045), posterior decentering on preoperative radiographs (p = 0.010), and less passive forward elevation at the time of discharge after ream-and-run arthroplasty (p < 0.001) to be significant risk factors for repeat procedures. Multivariate analysis found younger age (p = 0.040), ASA class 1 compared with class 3 (p = 0.020), and less passive forward elevation at discharge (p < 0.001) to be independent risk factors for repeat procedures. Of the patients who underwent open revision for stiffness, 69.2% had multiple positive cultures for Cutibacterium. Younger age, ASA class 1 compared with class 3, and less passive forward elevation in the immediate postoperative period were independent risk factors for repeat procedures to treat postoperative stiffness after ream-and-run arthroplasty. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Arthroscopic Posterior Articular Coverage and Shift (PACS) Procedure for Treatment of Preosteoarthritic Constitutional Static Posterior Shoulder Instability (Type C1)

Background: Different joint-preserving techniques for treatment of preosteoarthritic, constitutional static (type C1) posterior shoulder instability (PSI) have been proposed, including posterior glenoid open wedge osteotomy and bone graft augmentation. However, the techniques are demanding, the reported complication and reoperation rates are high, and posterior decentering cannot reliably be reversed. Purpose: To assess the clinical and radiological longitudinal outcomes of patients with type C1 PSI after arthroscopic posterior articular coverage and shift (PACS) surgery. Study Design: Case series; Level of evidence, 4. Methods: We performed a retrospective analysis of a prospective database with longitudinal follow-up including 14 shoulders in 13 patients who underwent an arthroscopic PACS procedure for symptomatic preosteoarthritic constitutional static posterior instability (type C1) with previous failed nonoperative treatment. Patients were clinically evaluated before surgery and at 3, 6, 12, and 24 months postoperatively in terms of satisfaction and pain levels as well as standardized physical examination, Subjective Shoulder Value (SSV), Western Ontario Shoulder Instability Index (WOSI) score, Constant score, and Rowe score. Preoperative, postoperative, and follow-up magnetic resonance imaging scans were obtained in all patients. A paired 2-sample t test was used to compare changes in continuous variable parameters over time. Correlation analyses were performed using the Pearson correlation coefficient. Results: All outcome scores and the pain level improved significantly from preoperatively to postoperatively, and the improvement was sustained over the follow-up period of 2 years (pain level, 6.4 preoperatively vs 3.3 at 2 years, P < .001; SSV, 40 vs 70, P = .001; WOSI, 33 vs 56, P = .001; Constant, 70 vs 79, P = .049; Rowe, 52 vs 76, P < .001). The mean glenohumeral and scapulohumeral subluxation indices were significantly lower in the early postoperative period compared with preoperative measurements (glenohumeral, 52% ± 6% vs 58% ± 10%, P = .02; scapulohumeral, 70% ± 8%; vs 77% ± 9%, P = .002, respectively); however, they returned to baseline values at follow-up (57% ± 7% vs 58% ± 10%, P = .7; 75% ± 6% vs 77% ± 9%, P = .4, respectively). A high scapulohumeral subluxation index, excessive glenoid retroversion, and increased posterior positioning of the humeral head in relation to scapular blade axis and older age were correlated with worse clinical outcomes. Conclusion: Over the follow-up period of 2 years, the PACS procedure significantly improved outcome scores in patients who had preosteoarthritic constitutional static posterior shoulder instability, especially in younger patients with less severe glenoid retroversion and posterior decentering of the humeral head. However, similar to other techniques, the PACS procedure needs to be considered a symptomatic therapy that does not reverse the underlying cause or stop the progressive pathology.

Early clinical and radiographic outcomes of anatomic total shoulder arthroplasty with a biconvex posterior augmented glenoid for patients with posterior glenoid erosion: minimum 2-year follow-up.

Glenoid bone loss in anatomic total shoulder arthroplasty (aTSA) remains a controversial and challenging clinical problem. Previous studies have shown high rates of glenoid loosening for aTSA in shoulders with retroversion, posterior bone loss, and posterior humeral head subluxation. This study is the first to present minimum 2-year follow-up data of an all-polyethylene, biconvex augmented anatomic glenoid component for correction of glenoid retroversion and posterior humeral head subluxation. This study is a multicenter, retrospective review of prospectively collected data on consecutive patients from 7 global clinical sites. All patients underwent aTSA using the biconvex posterior augmented glenoid (PAG). Inclusion criteria were preoperative computed tomographic (CT) scan, minimum 2 years since surgery, preoperative and minimum 2-year postoperative range of motion examination, and patient-reported outcome measures (PROMs). Glenoid classification, glenoid retroversion, and posterior humeral head subluxation were measured from preoperative CT and radiography and postoperative radiography. Statistical comparisons between pre- and postoperative values were performed with a paired t test. Eighty-six of 110 consecutive patients during the study period (78% follow-up) met the inclusion criteria and were included in our analysis. Mean follow-up was 35±10 months, with a mean age of 68±8 years (range 48-85). Range of motion statistically improved in all planes from pre- to postoperation. Mean visual analog scale score improved from 5.2 preoperation to 0.7 postoperation, Single Assessment Numeric Evaluation score from 43.2 to 89.5, Constant score from 41.8 to 76.9, and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score from 49.8 to 86.7 (all P<.0001). Mean glenoid retroversion improved from 19.3° to 7.4° (P<.0001). Posterior subluxation improved from 69.1% to 53.5% and posterior decentering improved from 5.8% to -3.0% (P<.0001). There was 1 patient with both a prosthetic joint infection and radiographic glenoid loosening that required revision. Seventy-nine of 86 patients had a Lazarus score of 0 (no radiolucency seen about peg or keel) at final follow-up. This study shows that at minimum 2-year follow-up, a posterior-augmented all-polyethylene glenoid can correct glenoid retroversion and posterior humeral head subluxation. Clinically, there was significant improvement in both range of motion and PROMs.

Posterior decentering of the humeral head in patients with arthroscopic rotator cuff repair.

BackgroundIn some patients with rotator cuff tear (RCT), the axial view of magnetic resonance imaging (MRI) shows subtle posterior decentering (PD) of the humeral head from the glenoid fossa. This is considered to result from a loss of centralization that is typically produced by rotator cuff function. There are few reports on PD in RCT despite the common occurrence of posterior subluxation in degenerative joint disease. In this study, we investigated the effect of PD in arthroscopic rotator cuff repair (ARCR).MethodsWe conducted a retrospective study of consecutive patients who underwent ARCR at our institute and were followed-up for at least 1 year. PD was identified as a 2-mm posterior shift of the humeral head relative to the glenoid fossa in the axial MRI view preoperatively. The tear size and fatty degeneration (FD, Goutallier classification) were also evaluated using preoperative MRI. Retears were evaluated through MRI at 1 year postoperatively.ResultsWe included 135 shoulders in this study. Ten instances of PD (including seven retears) were observed preoperatively. Fifteen retears (three and 12 retears in the small/medium and large/massive tear groups, respectively) were observed postoperatively. PD was significantly correlated with tear size, FD, and retear occurrence (p<0.01 each). The odds ratio for PD in retears was 34.1, which was greater than that for tear size ≥3 cm and FD grade ≥3.ConclusionsWe concluded that large tear size and FD contribute to the occurrence of PD. Furthermore, PD could be a predictor of retear after ARCR.

Total shoulder arthroplasty outcomes after noncorrective, concentric reaming of B2 glenoids

BackgroundTotal shoulder arthroplasty (TSA) is an effective procedure for the treatment of glenohumeral osteoarthritis (GHOA) delivering reliable pain relief and improved shoulder function. Abnormal glenoid morphologies are common, and biconcave glenoids are enigmas that have been associated with poor clinical outcomes and implant survivorship.PurposeTo assess the clinical outcome scores of patients who underwent noncorrective, concentric reaming for TSA with biconcave glenoids (B2). We hypothesized that patients with B2 glenoids who underwent TSA with glenoid implantation using noncorrective, concentric reaming would have significant improvements in clinical outcome scores and high implant survivorship.MethodsAll patients who underwent anatomic TSA for GHOA with B2 glenoids, performed by a single surgeon, between July 2006 and December 2015 with minimum 2-year follow-up were reviewed. Walch classification was obtained from preoperative imaging (magnetic resonance imaging or computed tomography). Clinical outcome scores were prospectively collected and included American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score, Single Assessment Numerical Evaluation (SANE) score, Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score, 12-Item Short Form Health Survey physical component summary (PCS), and patient satisfaction. Clinical failures (revision TSA surgery or conversion to reverse TSA) and complications were reported. Paired t test and bivariate correlations level of significance was set at P = .05. Survivorship analysis with implant failure as an endpoint was done using Kaplan-Meier survival curves.Results51 TSA in 49 patients (9 females, 40 males) with primary GHOA with B2 glenoids were performed with a mean age of 64 (range 36-81 years) at the time of surgery. The mean retroversion was 19.1° (range 5.4°-38°), and posterior decentering was 42.0% (range 19.4%-78.5%). At final evaluation, 45/51 anatomic TSAs (88% follow-up) with a mean follow-up of 4.9 years (range 2.0-10.4 years) were assessed. All clinical outcome scores improved significantly pre- to postoperatively: ASES, 52.5 to 79.6 (P < .001); SANE, 52.4 to 74.7 (P < .001); QuickDASH, 39.2 to 19.1 (P = .001); and PCS, 40.9 to 48.9 (P = .001). Median postoperative satisfaction was 9 (range 1-10). There were 2 failures and 4 that required another surgery —subscapularis repair, lysis of adhesions, irrigation and débridement, and one to explore the status of the subscapularis for persistent pain. The implant survivorship rate was 95% at a mean follow-up of 4.9 years.ConclusionAnatomic total shoulder replacement with minimally noncorrective, concentric reaming in patients with B2 glenoids had significant improvement in clinical outcome scores, high patient satisfaction, and high survivorship in this cohort.

Relationship of Posterior Decentering of the Humeral Head with Tear Size and Fatty Degeneration in Rotator Cuff Tear.

BackgroundPosterior decentering is not an uncommon finding on rotator cuff tear patients’ shoulder magnetic resonance imaging. No previous study has reported on the relationship between posterior decentering and rotator cuff tear.MethodsWe assessed patients’ rotator cuff tear humeral head positions based on humeral–scapular alignment (HSA). Subjects were classified into centering and decentering groups based on a <2 mm or >2 mm HSA value, respectively. Differences in rotator cuff tear size, degree of tear, and fatty degeneration between the two groups were evaluated.ResultsOne hundred seventy-five patients (80 males, 95 females; mean age: 59.7 ± 6.5 years old) were selected as subjects (case-control study; level of evidence: 3). Tear size, degree of subscapularis tendon tear, and fatty degeneration of the supraspinatus, infraspinatus, and subscapularis muscles were significantly different between the two groups (p<0.001, p<0.001, p<0.001).ConclusionsThe occurrence of decentering was related to rotator cuff tear size, degree of subscapularis tendon tear, and fatty degeneration of the rotator cuff muscles.

Prearthroplasty glenohumeral pathoanatomy and its relationship to patient's sex, age, diagnosis, and self-assessed shoulder comfort and function

There is great current interest in characterizing the prearthroplasty glenohumeral pathoanatomy because of its role in guiding surgical technique and its possible effects on arthroplasty outcome. We examined 544 patients within 6 weeks before arthroplasty with the goals of characterizing the following: demographic and radiographic characteristics; relationships of the radiographic pathoanatomy to the patient's age, sex, and diagnosis; inter-relationships among glenoid type, glenoid version, and amount of decentering of the humeral head on the glenoid; and relationships of the pathoanatomy to the patient's self-assessed comfort and function. Male patients had a higher frequency of B2 glenoids and a lower frequency of A2 glenoids. The arthritic shoulders of men were more retroverted and had greater amounts of posterior decentering. Patients with types A1 and C glenoids were younger than those with other glenoid types. Shoulders with osteoarthritis were more likely to be type B2 and to be retroverted. Types B2 and C had the greatest degree of retroversion, whereas types B1 and B2 had the greatest amounts of posterior decentering. Shoulders with glenoid types B1 and B2 and those with more decentering did not have worse self-assessed shoulder comfort and function. Glenohumeral pathoanatomy was found to have previously unreported relationships to the patient's sex, age, and diagnosis. Contrary to what might have been expected, more advanced glenohumeral pathoanatomy(ie, type B glenoids, greater retroversion, greater decentering) was not associated with worse self-assessed shoulder comfort and function.

Posterior Decentering of the Humeral Head on Shoulder MR Arthrography: Significant Association With Posterior Synovial Proliferation.

The purpose of this study is to analyze MRI findings associated with posterior decentering of the humeral head on shoulder MR arthrogram. A total of 255 MR arthrograms were obtained during a 10-month period. MR arthrograms in patients with posterior decentering of the humeral head (n = 33) were reviewed and compared with those of randomly selected control group without posterior decentering (n = 66). MR arthrograms were retrospectively evaluated by two observers for posterior factors (posterior synovial proliferation, posterior capsular thickening, and posterior labral abnormality), rotator cuff factors related to fatty degeneration, glenoid version, and anterior factors (subcoracoid bursa effusion and rotator interval tear). The chi-square test, Fisher exact test, and linear-by-linear association were used for comparison of categoric data; the t test was used for comparison of the glenoid version; and multivariate stepwise logistic regression analysis was performed. At univariate analysis, posterior synovial proliferation (27.3% [9/33] in the posterior decentering group vs 6.1% [4/66] in the control group; p = 0.003); posterior capsule thickening (21.2% [7/33] vs 0.0% [0/66]; p < 0.001); fatty infiltration of the supraspinatus, infraspinatus, and teres minor (linear-by-linear association values, 7.944, 10.496, and 5.985, respectively; p = 0.005, 0.001, and 0.014, respectively); and rotator interval tear (51.5% [17/33] vs 30.3% [20/66]; p < 0.04) were more frequently found in the posterior decentering group, with a statistically significant difference. At multivariate analysis, only the posterior synovial proliferation was significantly associated with posterior decentering of the humeral head (odds ratio, 7.675; 95% CI, 2.159-27.288). Posterior decentering of the humeral head is most significantly associated with posterior synovial proliferation. In addition, rotator cuff interval abnormalities and rotator cuff atrophy are associated with posterior decentering of the humeral head to a lesser extent. Awareness of the association of the posterior decentering of the humeral head with the factors described here will facilitate the effective interpretation of routine MR arthrograms in daily practice.

The three-dimensional glenohumeral subluxation index in primary osteoarthritis of the shoulder

Assessment of glenohumeral subluxation is essential in preoperative planning of total shoulder arthroplasty. The purpose of this study was to evaluate a 3-dimensional (3D) glenohumeral subluxation index (GHSI) in shoulders with primary osteoarthritis (OA) and its relationship with morbid glenoid retroversion. The 3D computed tomography reconstructions of 120 healthy shoulders and 110 shoulders with primary glenohumeral arthritis (OA group), classified according to Walch's glenoid morphology, were analyzed. The 3D GHSI was assessed by measuring posterior decentering of the humeral head in relation to the native glenoid in each subject, and its correlation to morbid glenoid version was calculated. The reproducible 3D GHSI (intraclass correlation coefficients ≥ 0.842) showed a posterior decentering of the humeral head in the OA population and in each type of glenoid morphology (P ≤ .005). A moderate correlation was observed in the OA group (r = -0.542; P < .001), but weak linear relationships were found for different glenoid morphology types (r between 0.041 and -0.307). Type A shoulders (r = -0.375; P = .006) correlated better than type B shoulders (r = -0.217; P = .104). After shoulders were subcategorized according to a threshold for 3D subluxation, the posteriorly subluxated group increased its correlation (r = -0.438; P < .001), whereas the centered shoulders still exhibited no relationship (r = -0.192; P = .329). Posterior humeral head decentering in relation to the native glenoid is present in each glenoid morphology type. Grouping measures according to morphology type and 3D subluxation showed at best moderate correlations between morbid version and 3D GHSI.

What Factors are Predictive of Patient-reported Outcomes? A Prospective Study of 337 Shoulder Arthroplasties.

Although shoulder arthroplasties generally are effective in improving patients' comfort and function, the results are variable for reasons that are not well understood. We posed two questions: (1) What factors are associated with better 2-year outcomes after shoulder arthroplasty? (2) What are the sensitivities, specificities, and positive and negative predictive values of a multivariate predictive model for better outcome? Three hundred thirty-nine patients having a shoulder arthroplasty (hemiarthroplasty, arthroplasty for cuff tear arthropathy, ream and run arthroplasty, total shoulder or reverse total shoulder arthroplasty) between August 24, 2010 and December 31, 2012 consented to participate in this prospective study. Two patients were excluded because they were missing baseline variables. Forty-three patients were missing 2-year data. Univariate and multivariate analyses determined the relationship of baseline patient, shoulder, and surgical characteristics to a "better" outcome, defined as an improvement of at least 30% of the maximal possible improvement in the Simple Shoulder Test. The results were used to develop a predictive model, the accuracy of which was tested using a 10-fold cross-validation. After controlling for potentially relevant confounding variables, the multivariate analysis showed that the factors significantly associated with better outcomes were American Society of Anesthesiologists Class I (odds ratio [OR], 1.94; 95% CI, 1.03-3.65; p = 0.041), shoulder problem not related to work (OR, 5.36; 95% CI, 2.15-13.37; p < 0.001), lower baseline Simple Shoulder Test score (OR, 1.32; 95% CI, 1.23-1.42; p < 0.001), no prior shoulder surgery (OR, 1.79; 95% CI, 1.18-2.70; p = 0.006), humeral head not superiorly displaced on the AP radiograph (OR, 2.14; 95% CI, 1.15-4.02; p = 0.017), and glenoid type other than A1 (OR, 4.47; 95% CI, 2.24-8.94; p < 0.001). Neither preoperative glenoid version nor posterior decentering of the humeral head on the glenoid were associated with the outcomes. The model predictive of a better result was driven mainly by the six factors listed above. The area under the receiver operating characteristic curve generated from the cross-validated enhanced predictive model was 0.79 (generally values of 0.7 to 0.8 are considered fair and values of 0.8 to 0.9 are considered good). The false-positive fraction and the true-positive fraction depended on the cutoff probability selected (ie, the selected probability above which the prediction would be classified as a better outcome). A cutoff probability of 0.68 yielded the best performance of the model with cross-validation predictions of better outcomes for 236 patients (80%) and worse outcomes for 58 patients (20%); sensitivity of 91% (95% CI, 88%-95%); specificity of 65% (95% CI, 53%-77%); positive predictive value of 92% (95% CI, 88%-95%); and negative predictive value of 64% (95% CI, 51%-76%). We found six easy-to-determine preoperative patient and shoulder factors that were significantly associated with better outcomes of shoulder arthroplasty. A model based on these characteristics had good predictive properties for identifying patients likely to have a better outcome from shoulder arthroplasty. Future research could refine this model with larger patient populations from multiple practices. Level II, therapeutic study.

Management of intraoperative posterior decentering in shoulder arthroplasty using anteriorly eccentric humeral head components

Posterior humeral decentering presents a challenge in glenohumeral arthroplasty. Soft tissue releases and osteophyte resection can lead to intraoperative decentering not evident preoperatively. Inferior outcomes result if decentering is not addressed as a part of the arthroplasty. When there is >50% posterior subluxation of the humeral head on passive elevation of the arm at surgery, we have used an anteriorly eccentric humeral head component to improve centering of the humeral articular surface on the glenoid. We reviewed the 2-year outcomes for 33 shoulder arthroplasties in which anteriorly eccentric humeral heads were used to manage posterior decentering identified at surgery. Rotator interval plication was performed in 16 cases as an adjunctive stabilizing procedure. Shoulders were evaluated preoperatively and postoperatively with the Simple Shoulder Test (SST). Radiographic centering was characterized before surgery and at follow-up on standardized axillary radiographs with the arm held in a position of functional elevation. With the anteriorly eccentric head component, preoperative radiographic humeral decentering was reduced from 10.4% ± 7.9% to 0.9% ± 2.3% postoperatively (P < .001). SST scores improved from 4.8 ± 2.3 to 10.0 ± 2.3 (P < .001). Preoperative posterior humeral head decentering did not correlate with preoperative glenoid version. Glenoid retroversion was 19.8° ± 8.9° preoperatively and 15.5° ± 7.5° postoperatively. Posterior decentering identified at surgery when standard trial components are in place can be addressed by replacing the anatomic humeral head with an anteriorly eccentric humeral head component.

Recentering the Humeral Head for Glenoid Deficiency in Total Shoulder Arthroplasty

Substantial posterior glenoid wear causing static posterior subluxation of the humeral head in patients with primary osteoarthritis has been described. Persistent humeral head subluxation after total shoulder arthroplasty can result in early polyethylene wear and glenoid component loosening. In our prospective cohort study, we hypothesized that in patients with posterior glenoid wear from osteoarthritis, static posterior decentering of the humeral head could be recentered during total shoulder arthroplasty by surgical correction of glenoid alignment in the transverse plane with soft tissue balancing. We performed total shoulder arthroplasties in 77 patients with primary osteoarthritis and a mean age of 67.6 years. The mean clinical and radiographic followup was 2 years (range, 1-7 years). Patients with preoperative posteriorly decentered humeral heads did not have posterior decentering develop postoperatively. Twenty patients (83.3%) had centered humeral heads and four patients (16.6%) had anterior decentering. Midterm results of total shoulder arthroplasties in shoulders with humeral head decentering caused by glenoid deficiency in the transverse plane showed correction of the decentering by lowering the high side or by bone grafting with soft tissue balancing can be well maintained.