The Effects of Arthroscopic Lateral Acromioplasty on the Critical Shoulder Angle and the Anterolateral Deltoid Origin: An Anatomic Cadaveric Study

The Relationship Between the Critical Shoulder Angle and the Incidence of Chronic, Full-Thickness Rotator Cuff Tears and Outcomes After Rotator Cuff Repair: A Systematic Review

PURPOSE

To summarize the available evidence and examine the relationship between the critical shoulder angle (CSA) and (1) the incidence of chronic full-thickness rotator cuff tears (RCTs) and (2) outcomes after rotator cuff repair (RCR).

METHODS

A comprehensive search of MEDLINE, Embase, and CINAHL was completed. Comparative studies were included and the influence of the CSA on either the incidence of chronic, full-thickness RCTs, or outcomes following RCR was evaluated. Demographic variables and outcomes were collected.

RESULTS

Seven comparative studies analyzed the influence of the CSA on the incidence of chronic, full-thickness RCTs (the control group constituted patients with a normal rotator cuff). High heterogeneity limited pooling of studies, but the majority concluded that a greater CSA significantly increased the likelihood of a chronic, full-thickness RCT. Conversely, 5 comparative studies analyzed the influence of CSA on outcomes following RCR, and although a greater CSA was associated with a greater re-tear rate, the majority reported that CSA did not significantly influence postoperative functional outcomes, including patient-reported outcome measures (PROMs), range of motion (ROM), and strength.

CONCLUSIONS

Based on the available evidence, there appears to be a relationship between a greater CSA and the presence of a chronic, full-thickness RCT. Furthermore, a greater CSA may be associated with a greater re-tear rate following RCR; however, CSA does not appear to influence functional outcomes following RCR. Despite these observations, the available evidence is of poor quality, and the clinical utility and role of the CSA in the diagnosis and surgical management of a chronic, full-thickness RCT remains in question.

LEVEL OF EVIDENCE

Level IV: Systematic review of Level II-IV studies.

Editorial Commentary: #Fakeradiographicangle-Critical Shoulder Angle, Like Acromioplasty, May Not Be Critical

The critical shoulder angle (CSA) is found to have an association with rotator cuff tearing when the angle is greater than 35° to 38°. However, the CSA does not correlate with improved clinical patient outcome scores. Acromioplasty is no longer viewed as a critical part of rotator cuff surgery. Only meaningful comparative studies will allow us to conclude whether performing a lateral acromioplasty for a significant CSA will be an important step to prevent future retears after rotator cuff repair.

Does an Increased Critical Shoulder Angle Affect Re-tear Rates and Clinical Outcomes Following Primary Rotator Cuff Repair? A Systematic Review

PURPOSE

To determine if an increased critical shoulder angle (CSA) predisposes patients to higher re-tear rates and worse clinical outcomes after rotator cuff (RC) repair.

METHODS

A comprehensive search of the PubMed, MEDLINE, and EMBASE databases was performed in October 2018 for English-language studies pertaining to RC repair and an increased CSA in accordance with Preferred Reported Items for Systematic Reviews and Meta-analyses guidelines. Studies of all levels of evidence were included provided that any outcomes, including pain, patient-reported outcomes, and re-tear rates, were reported.

RESULTS

Of a group of 1126 studies that satisfied the initial search criteria, 6 studies were included in the final analysis, comprising data from 473 patients. Three comparative studies were assessed for an association between increased CSA and RC re-tear rates. Among these 3 studies that compared RC re-tear rate in patients with larger and smaller CSAs, 22 of 97 patients (23%) with a larger CSA had a RC re-tear in comparison to 10 of 99 patients (10%) with a smaller CSA. All 3 studies demonstrated higher RC re-tear rates in patients with larger CSAs (risk ratio, 2.39-9.66, I² = 7%.) The mean CSA in those patients who did not have RC re-tears ranged from 34.3° to 37°, and the mean CSA in those patients who had RC re-tears ranged from 37° to 40°.

CONCLUSION

RC re-tear rates were higher in patients with larger CSAs among comparative, nonrandomized studies. However, the heterogeneity of the relevant literature limits the strength of his observation. Based on the current literature, it remains unclear as to whether lateral acromioplasty affects clinical outcomes as a function of a reduced postoperative CSA.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II to IV studies.

Effect of different geometrical structure of scapula on functional recovery after shoulder arthroscopy operation

Background

There are no published studies of the influence of geometry of the scapula on the postoperative recovery of rotator cuff injuries. Our aim was to explore the relationship between the critical shoulder angle (CSA), acromion index (AI), glenoid inclination (GI), and postoperative repair outcomes in shoulder joints after arthroscopic supraspinatus tendon repair.

Methods

Sixty two patients suffering a supraspinatus tear were analyzed retrospectively following failure of conservative treatment and subsequent shoulder arthroscopy in our hospital. Standard anterior and posterior X-rays of the injured shoulder had been performed prior to surgery, with follow ups for at least 2 years (24–43 months). Magnetic resonance imaging (MRI) was performed 2 years after surgery to assess repair of the supraspinatus tendon. Patients were divided into either the intact or re-tear group, according to the MRI results. In addition, assessments using the Constant Shoulder Score (CSS), the American Shoulder and Elbow Surgeon (ASES) Shoulder Assessment Form, the University of California at Los Angeles (UCLA) score and visual analog scale (VAS) score were performed to establish shoulder function at the 2-year evaluation for each patient.

Results

The mean CSA of all patients was 35.79° ± 3.59°, mean AI was 0.72 ± 0.05, and mean GI was 15.87° ± 3.62°. The CSA, AI, and GI in the intact group were statistically significantly different than the re-tear group (p < 0.05). There was no correlation between the magnitude of the CSA, AI, or GI and any shoulder function score (p > 0.05).

Conclusions

The geometry of the scapula had no significant effect on the recovery of postoperative function of patients with rotator cuff injury, but the value of the CSA, AI, and GI affected the risk of rotator cuff re-tear.

Editorial Commentary: Angles, Ratios, and Rotation-Is It Worth Splitting Hairs Over the Critical Shoulder Angle?

Various radiographic indices represent lateral acromial extension over the greater tuberosity and are said to be one of the etiologic factors in rotator cuff tears. There has been much debate regarding the accuracy of these parameters based on radiographic rotation and tilt. This commentary discusses the utility of the existing parameters and the "surgical worth" of seeking another accurate parameter that might avoid the measurement errors resulting from rotation.

The Effect of Critical Shoulder Angle on Clinical Scores and Retear Risk After Rotator Cuff Tendon Repair at Short-term Follow Up

The authors aimed to investigate whether standard acromioplasty can reduce critical shoulder angle (CSA) effectively and to investigate the effects of postoperative CSA on the clinical outcomes and retear rates. Patients are divided in to three groups: group 1 (24 patients): CSA under 35° before surgery, group 2 (25 patients): CSA over 35° before surgery and under 35° after surgery and group 3 (17 patients): CSA over 35° before and after surgery. Standard acromioplasty was performed if CSA is over 35 and no acromioplasty was performed if the CSA is already under 35. Preoperative and postoperative CSAs, UCLA, Constant-Murley clinical score and visual analog scale (VAS) pain score were measured. The size of the rotator cuff tear was classified by the Patte classification in preoperative MRI and the quality of the repair was evaluated as retear if discontinuity detected in the postoperative first year MRI. There were 31 female and 35 male patients with a mean age of 59.3 ± 4.5 years (range, 48–68) at the time of surgery. The mean CSA is reduced from 37.8° ± 1.4 to 34.9° ± 1.2 (p < 0.001) significantly for patients who underwent acromioplasty. In 25 (59.5%) of the 42 patients, the CSA was reduced to under 35°, whereas in the other 17 (40.5%) patients, it remained over 35°. The mean Constant and UCLA score was 46.4 ± 6.6; 18.5 ± 1.6 preoperatively and 82.4 ± 6.2; 31.1 ± 1.9 postoperatively respectively (p < 0,001). The mean VAS decreased from 4.94 ± 1.09 to 0.79 ± 0.71 (p < 0.001). No Clinical difference was seen between patients in which CSA could be reduced under 35° or not in terms of Constant-Murley score, UCLA and VAS score. Retear was observed in 2 (8.3%) patients in group 1, in 4 (16%) patients in group 2 and in 3 patients (17.6%) in group 3. There was not any significant difference between the patients who had retear or not in terms of neither the CSA values nor the change of CSA after the surgery. Standard acromioplasty, which consists of an anterolateral acromial resection, can reduce CSA by approximately 3°. This is not always sufficient to decrease the CSAs to the favorable range of 30°–35°. In addition, its effect on clinical outcomes does not seem to be noteworthy.

[Indications and techniques of arthroscopic anterior and lateral acromioplasty]

OBJECTIVE

Arthroscopic anterior acromioplasty (AAAP) for treatment of symptomatic subacromial spur. Arthroscopic lateral acromioplasty (ALAP) to reduce a pathological critical shoulder angle (CSA) and prevent rotator cuff re-tear after reconstruction.

INDICATIONS

AAAP is indicated for acromial impingement due to an anterolateral acromial spur with or without bursa-sided rotator cuff lesion. ALAP is indicated concomitant to arthroscopic rotator cuff repair if the CSA is pathologically increased.

RELATIVE CONTRAINDICATIONS

Irreparable rotator cuff tear with acetabularization of the acromion due to anterosuperior escape of the humeral head or symptomatic os acromiale can contraindicate for AAAP. Dehiscence of the origin of the deltoid muscle or symptomatic os acromiale can contraindicate for ALAP.

SURGICAL TECHNIQUE

To preform AAAP, arthroscopic subacromial decompression is followed by anterolateral resection of an acromion spur or ossification of the coracoacromial ligament. To perform ALAP, arthroscopic subacromial decompression and reconstruction of a rotator cuff-tear is followed by reduction of a pathologically increased CSA by resection of the lateral edge of the acromion.

POSTOPERATIVE MANAGEMENT

After isolated AAAP, physiotherapy can be performed without restriction. After AAAP or ALAP combined with rotator cuff repair, immobilization in a brace is recommended. The use of pain medication should be standardized and adapted to individual pain levels.

Does the critical shoulder angle decrease after anterior acromioplasty?

INTRODUCTION

No clinical studies to date have analyzed the critical shoulder angle (CSA) following anterior acromioplasty. Our study's main objective was to measure the change in the CSA after acromioplasty.

MATERIALS AND METHODS

Ninety patients were included in this retrospective series. The CSA and the type of acromion were evaluated before and after surgery.

RESULTS

The average CSA for patients before surgery was 35.9° (± 3.7, 26.2, 44.2) and 33° after the acromioplasty (± 3.5, 24.8, 41.4). The decrease was significant and 2.9° on average (± 2.2, - 2.2, 11.9, p = 0.000). Preoperatively, 58% of patients had a CSA ≥ 35° (n = 52) and 24% postoperatively (n = 22, p = 0.000).

CONCLUSIONS

Standardized anterior acromioplasty allows for a significant decrease in the CSA without lateral resection of the acromion. This study confirms the tight link between the CSA and the anterior acromion as well as the interest of this angle to quantify acromioplasty whether anterior or lateral.

LEVEL OF EVIDENCE

Level IV, Case Series, Retrospective design.

Epidemiological Analysis of Changes in Clinical Practice for Full-Thickness Rotator Cuff Tears From 2010 to 2015

Background:

Rotator cuff injuries are a leading cause of shoulder disability among adults. Surgical intervention is a common treatment modality; however, conservative management has been described for the treatment of rotator cuff tears. As the cost of health care increases, the industry has shifted to optimizing patient outcomes, reducing readmissions, and reducing expenditure. In 2010, the American Academy of Orthopaedic Surgeons created clinical practice guidelines (CPGs) to guide the management of rotator cuff injuries. Since their publication, there have been several randomized controlled trials assessing the management of rotator cuff injuries.

Purpose:

To quantitatively describe changes in the management of full-thickness rotator cuff tears over time with regard to the publication of the CPGs and prospective clinical trials.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included in the study were Humana-insured patients in the PearlDiver database with the diagnosis of a full-thickness rotator cuff tear from 2010 to 2015. Patients undergoing rotator cuff repair (CPT-29827, CPT-23410, CPT-23412, CPT-23420) and patients undergoing nonoperative management in the queried years were identified. The incidence of physical therapy (PT), nonsteroidal anti-inflammatory drugs (NSAIDs), and corticosteroid injections was assessed.

Results:

In 2015, patients with full-thickness rotator cuff tears were less likely to receive a corticosteroid injection (16.5% vs 23.9%, respectively; odds ratio [OR], 0.6; P < .001) or undergo PT (7.8% vs 12.1%, respectively; OR, 0.6; P < .001) before rotator cuff repair in comparison with 2010. Additionally, patients were no more likely to be prescribed NSAIDs before rotator cuff repair in 2015 in comparison with 2010 (OR, 1.0; P = .6). Patients with full-thickness rotator cuff tears were less likely to undergo acromioplasty in 2015 in comparison with 2010 (48.2% vs 76.9%, respectively; OR, 0.4; P < .001); however, the rate of concomitant biceps tenodesis slightly increased (14.8% vs 14.6%, respectively; OR, 1.1; P = .01).

Conclusion:

From 2010 to 2015, there were changes in the management of full-thickness rotator cuff tears, including decreased preoperative utilization of corticosteroid injections and PT as well as a decrease in concomitant acromioplasty, and the rate of biceps tenodesis slightly increased. As CPGs and prospective investigations continue to proliferate, management practices of patients with full-thickness rotator cuff tears continue to evolve.

The critical shoulder angle: can it be sufficient to reflect the shoulder joint without the humeral head?

HYPOTHESIS

We hypothesized that a new method considering the humeral head would distinguish rotator cuff tears (RCTs) and osteoarthritis (OA) better than the critical shoulder angle (CSA).

METHODS

A total of 1011 patients were tested in this study and divided into 4 groups: those with RCTs (n = 493), those with OA (n = 73), those with anterior instability (n = 361), and those with adhesive capsulitis (n = 84). The CSA and new radiologic parameters including the humeral head were measured in the true anterior-to-posterior view: the Y angle connecting the lower end of the glenoid (LG), the center of the humeral head (CH), and the upper end of the glenoid (UG); the G angle connecting UG, CH, and the lateral tip of the acromion; the YG angle connecting LG, CH, and the lateral tip of the acromion; and the R angle connecting UG, LG, and CH.

RESULTS

The CSA and G angle were the largest in the RCT group (34.2° and 70.4°, respectively; P < .001) and the smallest in the OA group (29.8° and 61.7°, respectively; P < .001). The Y angle was the largest in the OA group (82.8°, P < .001). The R angle in the RCT group (52.9°) was significantly larger than that in the OA group, which was the smallest among the groups (48.0°; P < .001). The CSA was correlated with the G and YG angles in the RCT group, whereas the CSA was correlated with the Y, G, and R angles in the OA group (P < .05). The CSA showed the highest correlation with the size of RCTs (correlation coefficient = 0.138).

CONCLUSION

The Y, G, and R angles reflected the lesions of RCTs or OA. The CSA showed good correlations with the new radiologic parameters, and it had the highest correlation coefficient with the size of RCTs.

Critical shoulder angle: Acromial coverage is more relevant than glenoid inclination

It is still unknown whether glenoid inclination or lateral acromial roof extension is a more important determinant for development of rotator cuff tears (RCT) or osteoarthritis (OA) of the shoulder. It was the purpose of this study, to evaluate whether there is a potential predominance of one of these factors in pathogenesis of RCT or concentric OA. We analyzed 70 shoulders with advanced degenerative RCT and 54 shoulders with concentric OA undergoing primary shoulder arthroplasty (anatomical or reverse) using antero-posterior radiography and multiplanar computed tomography. The two groups were compared in relation to glenoid inclination, lateral acromion roof extension, acromial height, and critical shoulder angle (CSA). All measured parameters were highly significantly different between RCT and concentric OA (p < 0.001). Based on Cohen's d effect size, group differences were most distinct in lateral acromial roof extension (1.36_x-ray , 0.92_ct ) compared with acromial height (1.06_x-ray , 0.73_ct ) and glenoid inclination (0.60_x-ray , 0.61_ct ). However, no single factor showed an effect size which was as high as that of the CSA (1.63_x-ray ). Interestingly, a ratio of lateral acromion roof extension and acromial height could enhance the effect size (1.60_x-ray , 1.16_ct ) near to values of the CSA (1.63_x-ray ). In summary, lateral acromial roof extension has a greater influence in pathogenesis of degenerative RCT and concentric OA than acromial height or glenoid inclination. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

High performance of critical shoulder angle for diagnosing rotator cuff tears on radiographs

PURPOSE

Previous studies have reported that a high critical shoulder angle (CSA) is associated with rotator cuff tears (RCTs). However, the available evidence concerning the strength of the association of these parameters with the pathogenesis of RCTs is conflicting. The aim in the present meta-analysis was to assess the diagnostic performance of CSA for detecting RCTs.

METHODS

The PubMed and EMBASE databases were searched for diagnostic accuracy studies of CSA for detecting RCT. Quality of the included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. We calculated the pooled diagnostic accuracy of CSA, including diagnostic odd ratios (DORs) with 95% confidence intervals (CIs). Bivariate random-effect modeling with forest plots and hierarchical summary receiver operating characteristic curves was performed to evaluate the pooled sensitivity and specificity of CSA. For heterogeneity exploration, we performed meta-regression analyses.

RESULTS

Eight studies including 902 patients (460 patients with RCT and 442 control patients) were included. According to DOR, CSA was an informative feature for RCT (DOR 8; 95% CI 4-16). The overall diagnostic performance of CSA for RCT was good (sensitivity 71% [95% CI 61-80%]; specificity, 77% [95% CI 65-86%]). Meta-regression analyses revealed that the sensitivity of CSA could be higher for differentiating full-thickness RCTs and normal patients. Furthermore, the specificity of CSA could be higher using a cut-off value of 35°.

CONCLUSION

CSA on plain radiographs has good diagnostic performance for RCTs. A cut-off value of 35° is recommended for more accurate diagnosis of full-thickness RCTs. Measuring CSA on plain radiographs may provide clinicians with a readily available and reliable method for detecting RCT in daily practice.

LEVEL OF EVIDENCE

Diagnostic studies, Level III.

Influence of the site of acromioplasty on reduction of the critical shoulder angle (CSA) - an anatomical study

Background

A large critical shoulder angle (CSA) >35° is associated with the development of rotator cuff tearing. Lateral acromioplasty (AP) has the theoretical potential to prevent rotator cuff tearing and/ or to reduce the risk of re-tears after repair. It is, however unclear which part of the lateral acromion has to be reduced to obtain the desired CSA. It was the purpose of this study to determine which part of the lateral acromion has to be resected to achieve a desired reduction of the CSA in a given individual.

Methods

First, the influence of the exact radiographic projection on the CSA was examined. Second, the influence of anterolateral versus strict lateral AP on the CSA was studied in eight scapulae with different anatomic characteristics. Differences in CSA reduction were investigated using paired t-test or Wilcoxon test.

Results

Scapular rotation in the sagittal and axial plane had a marked influence on the radiologically measured CSA ranging from -6 to +16°. Overall, lateral AP of 5/10mm reduced the CSA significantly greater than anterolateral AP of 5mm/10mm [5mm: 2.3° (range: 0.7°-3.6°) SD±0.8° vs. 1.2° (range: 0°-3.3°) SD±1.1°, p=0.0002]/[10mm: 4.8° (range: 2.1°-7°) SD±1.3° vs. 2.7° (range: 0°-5.3°) SD±1.7°, p=0.0001]. Depending on scapular anatomy anterolateral AP did not alter CSA at all.

Conclusions

For comparison of pre- and postoperative CSA, the exact orientation of the X-ray and the spatial orientation of the scapula must be as identical as possible. Anterolateral AP may not sufficiently correct CSA in scapulae with great acromial slopes and smaller relative external rotation of the acromion as the critical acromial point (CAP) may be located too posteriorly and thus is not addressed by anterolateral acromioplasty. Consistent reduction of the CSA could be achieved by lateral AP in all eight scapulae.

Acromial roof in patients with concentric osteoarthritis and massive rotator cuff tears: multiplanar analysis of 115 computed tomography scans

BACKGROUND

There is evidence for differences of scapular shape between shoulders with rotator cuff tears (RCT) and osteoarthritic shoulders (OA). This study analyzed orientation and shape of the acromion in patients with massive RCT and concentric OA (COA) in a multiplanar computed tomography (CT) analysis.

METHODS

CT scans of 70 shoulders with degenerative RCT and 45 shoulders with COA undergoing primary shoulder arthroplasty were analyzed. The 2 groups were compared in relation of (1) shape of the acromion, (2) its orientation in space, and (3) the anteroposterior glenoid coverage in relation to the scapular plane.

RESULTS

Lateral acromial roof extension was an average of 4.6 mm wider and the acromial area was an average of 156 mm² larger in RCT than in COA (P < .001). Significant differences of the lateral extension of the acromion margin were limited to the anterior two-thirds. Acromial roof orientation in RCT was average of 10.8° more "externally rotated" (axial plane: P < .001) and an average of 7.8° more tilted downward (coronal plane: P < .001) than in COA. The glenoid in RCT was an average of 5.5° (P < .001) more covered posteriorly compared with COA.

CONCLUSIONS

A more externally rotated (axial plane), more downward tilted (coronal plane), and wider posterior covering acromion was more frequent in patients with massive RCT than COA.

Higher Critical Shoulder Angle and Acromion Index Are Associated With Increased Retear Risk After Isolated Supraspinatus Tendon Repair at Short-Term Follow Up

PURPOSE

To evaluate the effect of critical shoulder angle (CSA), acromion index (AI), and glenoid inclination (GI) on the postoperative healing rate after arthroscopic supraspinatus tendon repair.

METHODS

Patients after arthroscopic repair of a symptomatic, unilateral, single-tendon, full-thickness supraspinatus tear in whom nonoperative management had failed were retrospectively reviewed. Magnetic resonance imaging (MRI) studies were obtained 6 months postoperatively and were evaluated by 2 independent observers. Repair integrity was classified as either intact or torn. Preoperative true anteroposterior radiographs were used to measure CSA, AI, and GI.

RESULTS

Fifty-seven patients were evaluated 6 months postoperatively. The mean patient age at surgery was 54.7 ± 7.7 years. On MRI studies, 41 patients (71.9%) had an intact repair and 16 patients (28.1%) had a full-thickness retear. There were no significant differences between the intact and retear group in regard to patient age (P = .648), initial tear size (P = .205), or fatty degeneration (P = .508). The mean CSA for the retear group (37° ± 4°) was significantly higher than that in the intact group (35° ± 3°; P = .014). If the CSA was >38°, the odds ratio of having a retear was 3.78 (95% confidence interval 1.05 to 13.58; P = .042). Average AI for the retear group (0.73 ± 0.09) was significantly higher than that in the intact group (0.69 ± 0.06; P = .049). The mean GI was 17° ± 6° for the intact group and 16° ± 6° for the retear group (P = .739).

CONCLUSIONS

At short-term follow-up, higher CSA and AI significantly increased the retear risk after arthroscopic supraspinatus tendon repair. CSA >38° increased the retear risk almost 4-fold. Overall GI was elevated but did not correlate with failure rate.

LEVEL OF EVIDENCE

III, case control study.

A simple method to directly evaluate the lateral extension of the acromion: an anatomic study of 128 cadaveric scapulae

BACKGROUND

The lateral extension of the acromion from the glenohumeral joint is the critical variable that both the acromial index and critical shoulder angle reflect. The purpose of this study was to establish a simple and reproducible method to directly measure the lateral extension of the acromion that will be independent of patient demographic characteristics, scapular rotation, or other morphologic features of the shoulder.

METHODS

This study used 128 unpaired cadaveric scapulae with a mean age of 69.4 ± 11.1 years (66 right and 62 left scapulae, 65 female and 63 male cadaveric specimens). The lateral extension of the acromion was measured from the supraglenoid tubercle to the most lateral point of the acromion with a digital caliper placed perpendicular to the scapula long axis. This distance was called the "lateral offset of the acromion."

RESULTS

The lateral offset was 2.62 ± 0.72 cm in men and 2.69 ± 0.73 cm in women. The offset was 2.61 ± 0.66 cm in right and 2.70 ± 0.78 cm in left scapulae. The offset in the group aged 46-60 years was 2.85 ± 0.76 cm; in the group aged 61-75 years, it was 2.62 ± 0.76 cm; and in the group aged 76 years or older, it was 2.54 ± 0.60 cm. No significant difference was found between any of the groups.

CONCLUSIONS

This study established a simple method to directly measure the lateral extension of the acromion based on the longitudinal axis of the scapula, which eliminates bias that may exist in the acromial index and critical shoulder angle from the position of the scapula and glenoid inclination. The lateral offset was found to be independent of sex, side, or age, limiting bias in a potential future clinical application.

Superior glenoid inclination and rotator cuff tears

BACKGROUND

The objectives of this study were to determine whether glenoid inclination (1) could be measured accurately on magnetic resonance imaging (MRI) using computed tomography (CT) as a gold standard, (2) could be measured reliably on MRI, and (3) whether it differed between patients with rotator cuff tears and age-matched controls without evidence of rotator cuff tears or glenohumeral osteoarthritis.

METHODS

In this comparative retrospective radiographic study, we measured glenoid inclination on T1 coronal MRI corrected into the plane of the scapula. We determined accuracy by comparison with CT and inter-rater reliability. We compared glenoid inclination between patients with full-thickness rotator cuff tears and patients aged >50 years without evidence of a rotator cuff tear or glenohumeral arthritis. An a priori power analysis determined adequate power to detect a 2° difference in glenoid inclination.

RESULTS

(1) In a validation cohort of 37 patients with MRI and CT, the intraclass correlation coefficient was 0.877, with a mean difference of 0° (95% confidence interval, -1° to 1°). (2) For MRI inclination, the inter-rater intraclass correlation coefficient was 0.911. (3) Superior glenoid inclination was 2° higher (range, 1°-4°, P < .001) in the rotator cuff tear group of 192 patients than in the control cohort of 107 patients.

CONCLUSIONS

Glenoid inclination can be accurately and reliably measured on MRI. Although superior glenoid inclination is statistically greater in those with rotator cuff tears than in patients of similar age without rotator cuff tears or glenohumeral arthritis, the difference is likely below clinical significance.

Impact of vertical and horizontal malrotation on measurements of anteroposterior radiographs of the scapula: need for standardized images in modern omometry

BACKGROUND

An increasing number of parameters measured on anteroposterior radiographs are used for the evaluation of the bony geometry of the scapula. Inhomogeneous acquisition of images is common because of the lack of standardization in radiographic positioning. Images with malrotation around the horizontal axis of the scapula are particularly frequent. We hypothesized that malrotated images would result in large variations in measured radiographic parameters and that image standardization using qualitative and semiquantitative "omometric" criteria would decrease these variations in measurements. "Omometry" is a newly introduced umbrella term that contains all standardized measurements on plain radiographs of the shoulder, analogous to the term "coxometry," which is widely used for the radiographic assessment of the osseous pelvis and hip.

METHODS

In this experimental, cadaveric radiographic study, 7 dry-bone human scapula cadaveric specimens from anonymous donors were used to obtain 210 radiographs. We incrementally rotated (steps of 3°) every scapula around its horizontal and vertical axis, with a total range of 42° per each axis. Then, we measured 5 radiographic parameters on every image and observed their change with malrotation. Furthermore, we introduced 4 omometric criteria defining an appropriate (presence of ≥3 criteria) radiographic image to improve standardization of scapular image acquisition.

RESULTS

Overall, measured values remained stable within a narrow range of ±9° of malrotation. Beyond this range, values of all parameters significantly deviated (>±2°) from the initial value. Measurements on appropriate images were significantly less prone to deviation. Within the appropriate images, those with 4 criteria showed a higher specificity than those with 3 criteria.

CONCLUSION

There is significant variation in values of measured radiographic parameters on anteroposterior radiographs of the scapula with substantially malrotated images. With the use of the 4 newly introduced semiquantitative and qualitative omometric criteria, which define an appropriate image, reliability of the measured parameters can be significantly improved.

Editorial Commentary: Lateral Acromioplasty Is Clinically Safe and Has the Potential to Reduce the Risk for Rotator Cuff Re-tears

The critical shoulder angle and lateral acromioplasty are areas of controversy that are being studied in association with rotator cuff tears both as potential pathogenic variables and as surgically modifiable variables that could improve clinical outcomes. Current clinical evidence regarding the effectiveness and potential benefit of lateral acromioplasty support the hypothesis that modification of the bony anatomy may influence the integrity of the rotator cuff.

Arthroscopic Correction of the Critical Shoulder Angle Through Lateral Acromioplasty: A Safe Adjunct to Rotator Cuff Repair

PURPOSE

To investigate whether arthroscopic lateral acromioplasty reliably decreases the critical shoulder angle (CSA) and whether it is associated with damage to the deltoid or other complications.

METHODS

Patients undergoing arthroscopic rotator cuff repair (RCR) with lateral but without anterior acromioplasty for degenerative, full-thickness rotator cuff tears and a CSA of 34° or greater were retrospectively reviewed. Patients with traumatic or irreparable rotator cuff tears, osteoarthritis, or previous surgery were excluded. Clinical and radiographic outcomes were assessed at a minimum of 12 months' follow-up.

RESULTS

We reviewed 49 consecutive patients (mean age, 56 years; age range, 39-76 years) at a mean of 30 months (range, 12-47 months). There were 7 RCR failures (14%). The mean CSA was reduced from 37.5° preoperatively (95% confidence interval [CI], 36.7°-38.3°) to 33.9° postoperatively (95% CI, 33.3°-34.6°; P < .001). There were no cases of dehiscence, increases in fatty infiltration, or significant atrophy of the deltoid. Scarring at the deltoid origin was noted in 18 patients (37%). The mean absolute and relative Constant scores increased from 59 points (95% CI, 54-64 points) to 74 points (95% CI, 70-78 points) and from 66% (95% CI, 61%-71%) to 83% (95% CI, 79%-87%) respectively, and the Subjective Shoulder Value increased from 45% (95% CI, 39%-50%) to 80% (95% CI, 74%-86%) (P < .001 for all 3 improvements). The postoperative CSA was significantly larger in failed than in healed repairs (P = .026). Patients with a healed RCR and a CSA corrected to 33° or less (n = 22) had 25% more abduction strength than patients with a healed cuff and a CSA corrected to 35° or greater (n = 14, P = .04).

CONCLUSIONS

Arthroscopic lateral acromioplasty performed in addition to arthroscopic RCR can reduce the CSA without significantly compromising the deltoid origin, deltoid muscle, or function. It is not associated with any additional complications of arthroscopic RCR. Insufficiently corrected, abnormally large CSAs are associated either with a higher retear rate or with inferior strength of abduction if the tears heal.

LEVEL OF EVIDENCE

Level IV, case series, treatment study.

Partial and Full-Thickness RCT: Modern Repair Techniques

PURPOSE OF REVIEW

The purpose of this article is to review the recent literature concerning modern repair techniques related to partial- and full-thickness rotator cuff tears.

RECENT FINDINGS

The understanding of rotator cuff pathology and healing continues to evolve, beginning with emerging descriptions of the anatomic footprint and natural history of rotator cuff tears. Significant controversy remains in treatment indications for partial-thickness rotator cuff lesions as well as optimal surgical repair techniques for both partial- and full-thickness tears. Techniques such as margin convergence and reduction of the so-called "comma" tissue have improved the ability to anatomically reduce large and retracted tears. Repair strength and contact pressures are improved with double-row repairs and transosseus-equivalent techniques compared to traditional single-row repairs. Future work is directed towards obtaining reliable radiographic healing and demonstrating clinical superiority and cost-effectiveness of a single technique. Much recent work regarding rotator cuff anatomy and pathology has been reported. Newer techniques improve repair strength. Despite these advances, significant questions remain concerning surgical indications and clinical outcomes.

ArthroPlanner: a surgical planning solution for acromioplasty

PURPOSE

We present a computer-assisted planning solution "ArthroPlanner" for acromioplasty based on 3D anatomical models, computed tomography and joint kinematic simulations.

METHODS

In addition to a standard static clinical evaluation (anamnesis, radiological examination), the software provides a dynamic assessment of the shoulder joint by computing in real time the joint kinematics from a database of activities of daily living. During motion, the precise bone resection (location and amount) is computed based on detected subacromial impingements, providing surgeons with precise information about the surgical procedure. Moreover, to improve the subjective reading of medical images, the software provides 3D measurement tools based on anatomical models assisting in the analysis of shoulder morphological features.

RESULTS

We performed an in vivo assessment of the software in a prospective randomized clinical study conducted with 27 patients beneficiating from the planning solution and a control group of 31 patients without planning. Postoperatively, patient's pain decreased, and the shoulder range of motion and the functional outcomes improved significantly and the rotator cuff healing rate was good for both groups without intergroup differences. The amount of bone resected at surgery was comparable between the groups. The percentage of remaining impingement after surgery was in average reduced to 51% without groups difference.

CONCLUSIONS

ArthroPlanner software includes all required materials (images data, 3D models, motion, morphological measurements, etc.) to improve orthopedists' performance in the surgical planning of acromioplasty. The solution offers a perfect analysis of the patient's anatomy and the ability to precisely analyze a dynamic mechanism to fully apprehend the patient's condition and to fulfill his/her expectations. The study however failed to detect any statistically significant difference in clinical outcomes and bone resection between the groups. Short-term clinical and radiological results were excellent in both groups.

The critical acromial point: the anatomic location of the lateral acromion in the critical shoulder angle

BACKGROUND

Acromioplasty has been proposed as a means of altering elevated critical shoulder angles (CSAs). We aimed to localize the critical acromion point (CAP) responsible for the acromial contribution of the CSA and determine whether resection of the CAP can alter the CSA to a normal range.

METHODS

The CAP and 3-dimensional (3D) CSAs were determined on 3D computed tomography reconstructions of 88 cadaveric shoulders and compared with corresponding CSAs on digitally reconstructed radiographs. The position of the CAP was fluoroscopically isolated in 20 of these specimens and the resulting fluoroscopic CSA compared with the corresponding 3D CAP and 3D CSA. We investigated the CSA before and after a virtual acromioplasty of 2.5 and 5 mm at the CAP in specimens with a CSA greater than 35°.

RESULTS

The mean CAP was 21% ± 10% of the acromial anterior-posterior length from the anterolateral corner. There was no difference between the mean 3D CSA and the CSA on digitally reconstructed radiographs (32° vs 32°, P = .096). No difference between the mean fluoroscopic CSA and 3D CSA was found (31° vs 31°, P = .296). A 2.5-mm acromial resection failed to reduce the CSA to 35° or less in 7 of 13 shoulders, whereas a 5-mm resection reduced the CSA to 35° or less in 12 of 13.

CONCLUSION

The CAP was localized to the anterolateral acromial edge and was easily identified fluoroscopically. A 5-mm acromial resection was effective in reducing the CSA to 35° or less. These data can guide surgeons in where and how to alter the CSA if future studies demonstrate a clinical benefit to surgically modifying this radiographic parameter.

The critical shoulder angle is associated with osteoarthritis in the shoulder but not rotator cuff tears: a retrospective case-control study

BACKGROUND

In 2013 Moor et al introduced the concept of the critical shoulder angle (CSA) and suggested that an abnormal CSA was a leading factor in development of rotator cuff tear (RCT) and osteoarthritis (OA) of the shoulder. This study assessed whether the CSA was associated with RCT and OA and tested the inter- and intrarater reliability of the CSA when measuring RCT and OA.

MATERIALS AND METHODS

The study was performed as a retrospective case-control study. The cases comprised 2 groups: 97 patients with RCT and 87 patients with OA. The controls were matched 3:1, by age and sex, from a population of 795 patients with humeral fractures. The CSA was measured as described by Moor et al. Analysis of the relation with CSA for RCT and OA was done by logistic regression. Models were fitted separately for RCT and OA and used the controls matched to the respective cases. Inter- and intrarater reliability was determined by measuring the intraclass correlation coefficient and minimal detectable change.

RESULTS

The mean CSA was 33.9° in the RCT group and 33.6° in the matched control group. The odds ratio for developing RCT for people with a CSA above 35° was 1.12 (P = .63). The mean CSA in the OA group was 31.1° and in the matched control group 33.3°. The odds ratio for developing OA for people with a CSA below 30° was 2.25 (P = .002). The CSA measurements showed strong intra- and inter-rater reliability, with intraclass correlation coefficient values above 0.92 and minimal detectable change values below 0.4°.

CONCLUSIONS

This study did not find any association between CSA and RCT but did show association between CSA and OA, with a 2.25 odds ratio of developing OA given the patient had a CSA below 30°. The results do not support the suggested praxis of shaving away the lateral border of the acromion to make the CSA smaller because it might increase the risk of developing OA without decreasing the risk of developing RCT. The CSA measurements showed excellent intra- and inter-rater reliability.

Brunner U. Impingement Syndrome of the Shoulder

BACKGROUND

Shoulder pain is the third most common musculoskeletal complaint in orthopedic practice. It is usually due to a defect of the rotator cuff and/or an impingement syndrome.

METHODS

This review is based on pertinent literature retrieved by a selective search of the Medline database.

RESULTS

Patients with shoulder impingement syndrome suffer from painful entrapment of soft tissue whenever they elevate the arm. The pathological mechanism is a structural narrowing in the subacromial space. A multiplicity of potential etiologies makes the diagnosis more difficult; it is established by the history and physical examination and can be confirmed with x-ray, ultra - sonography, and magnetic resonance imaging. The initial treatment is conservative, e.g., with nonsteroidal antiinflammatory drugs, infiltrations, and patient exercises. Conservative treatment yields satisfactory results within 2 years in 60% of cases. If symptoms persist, decompressive surgery is performed as long as the continuity of the rotator cuff is preserved and there is a pathological abnormality of the bursa. The correct etiologic diagnosis and choice of treatment are essential for a good outcome. The formal evidence level regarding the best treatment strategy is low, and it has not yet been determined whether surgical or conservative treatment is better.

CONCLUSION

Randomized controlled therapeutic trials are needed so that a standardized treatment regimen can be established.

Critical Shoulder Angle and Acromial Index Do Not Influence 24-Month Functional Outcome After Arthroscopic Rotator Cuff Repair

BACKGROUND

Recent studies have shown a correlation between scapular geometry and the development of atraumatic rotator cuff tears. However, a paucity of literature is available on the effects of critical shoulder angle (CSA) and acromial index (AI) on functional outcomes after arthroscopic rotator cuff repair. Hypothesis/Purpose: The purpose was to investigate the influence of CSA and AI on 24-month functional outcomes after arthroscopic rotator cuff repair. The hypothesis was that a larger CSA or AI would result in poorer postoperative outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The study included 147 patients who underwent arthroscopic double-row rotator cuff repair for radiologically documented full-thickness supraspinatus tears. An independent reviewer measured the CSA and AI on preoperative radiographs. These patients were prospectively enrolled and were evaluated preoperatively as well as at 3, 6, 12, and 24 months postoperatively. Functional outcome was assessed with the Constant Shoulder Score (CSS), Oxford Shoulder Score (OSS), and University of California at Los Angeles (UCLA) Shoulder Rating Scale. The patients were first divided based on CSA: (1) ≤35° (control CSA) and (2) >35° (increased CSA); and then based on AI: (1) ≤0.7 and (2) >0.7. The Student unpaired t test, Pearson chi-square test, and Pearson correlation were performed to examine the influence of CSA and AI on postoperative functional outcome scores.

RESULTS

At 6 months of follow-up, the CSS, OSS, and UCLA Shoulder Rating Scale were 10 ± 1, 4 ± 2, and 3 ± 1 points poorer in the increased CSA group compared with the control CSA group ( P = .005, P = .030, and P = .035, respectively). These scores were not significantly different between both AI groups. By 24 months of follow-up, all outcome scores were comparable between both CSA groups as well as between both AI groups. No significant correlation was found between either CSA or AI when compared with CSS, OSS, or UCLA Shoulder Rating Scale at 24 months of follow-up.

CONCLUSION

CSA and AI do not appear to influence 24-month functional outcomes postoperatively and hence are not contraindications to arthroscopic rotator cuff repair.

Rotator Cuff Tears at the Musculotendinous Junction: Classification and Surgical Options for Repair and Reconstruction

Although uncommon, rotator cuff tears that occur medially at the musculotendinous junction can result from acute trauma, anatomic force imbalance, or medial row cuff failure following a previous rotator cuff repair. The quality of the torn muscle and tendon along with the length of the remnant tendon stump should be considered before deciding on the most appropriate repair technique. When muscle and tendon quality are sufficient, the tear can often be repaired directly to the remnant tendon stump and compressed onto the greater tuberosity. If the remnant tendon stump is degenerative, of insufficient length, or lacks tendon in which to place sutures, an allograft patch can be used to augment the repair. When the quality of the remaining muscle and tendon are poor or when the muscle is retracted too far medially and is nonmobile, a bridging technique such as superior capsule reconstruction is preferable. The purpose of this report is to (1) highlight that medial cuff failure can occur both primarily and after previous repair; (2) define and classify the 3 major tear patterns that are encountered, and (3) describe the authors' preferred techniques for medial cuff repair that specifically address each of the major tear patterns.

Acromion and glenoid shape: Why are they important predictive factors for the future of our shoulders?

The shape of the acromion differs between patients with degenerative rotator cuff tears and individuals without rotator cuff pathology.It can be assessed in the sagittal plane (acromion type, acromion slope) and in the coronal plane (lateral acromion angle, acromion index, critical shoulder angle).The inter-observer reliability is better for the measurements in the coronal plane.A large lateral extension (high acromion index or high critical shoulder angle) and a lateral down-sloping of the acromion (low lateral acromion angle) are associated with full-thickness supraspinatus tears.The significance of glenoid inclination for rotator cuff disease is less clear.The postulated patho-mechanism is the compression of the supraspinatus tendon between the humeral head and the acromion. Bursal side tears might be caused by friction and abrasion of the tendon. Articular side tears could be due to impairment of the gliding mechanism between tendon fibrils leading to local stress concentration. Further research is needed to understand the exact pathomechanism of tendon degeneration and tear. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160076. Originally published online at www.efortopenreviews.org.

Is There an Association Between the "Critical Shoulder Angle" and Clinical Outcome After Rotator Cuff Repair?

BACKGROUND

Variations in scapular morphology have been associated with the development of atraumatic rotator cuff tears (RCTs). The critical shoulder angle (CSA) accounts for both glenoid inclination and lateral extension of the acromion. The impact of the CSA on outcomes after rotator cuff repair (RCR) has not been investigated previously.

HYPOTHESIS

Our hypothesis was that individuals with smaller CSAs will have better patient-reported outcome scores over time compared with those with larger CSAs. Theoretically, a smaller CSA minimizes the biomechanical forces favoring superior translation of the humeral head, which may be advantageous after RCR. This is the first study to examine the relationship between the CSA and clinical outcomes after RCR.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Fifty-three patients (mean age, 61 years) with atraumatic full-thickness RCTs who underwent arthroscopic RCR were prospectively evaluated. Demographic data as well as the Western Ontario Rotator Cuff Index (WORC) score, American Shoulder and Elbow Surgeons (ASES) score, and a visual analog scale (VAS) for pain were prospectively collected at various time points up to 24 months postoperatively. Statistical analysis included longitudinal multilevel regression modeling to investigate the association between the CSA and the WORC, ASES, and VAS scores.

RESULTS

The overall clinical outcome, as measured by the WORC, ASES, and VAS, improved significantly (P < .0001). Controlling for demographic and clinical characteristics, a multilevel regression analysis demonstrated that the CSA was not a significant independent predictor for change in WORC (P = .581), ASES (P = .458), or VAS (P = .859) scores at 24 months after arthroscopic RCR. Interobserver and intraobserver reliability for CSA measurements resulted in interclass correlation coefficients of 0.986 and 0.982, respectively (P < .001), indicating excellent agreement.

CONCLUSION

The CSA did not appear to be a significant predictor of patient-reported outcomes after arthroscopic repair of atraumatic full-thickness RCTs.

Impact of Arthroscopic Lateral Acromioplasty on the Mechanical and Structural Integrity of the Lateral Deltoid Origin: A Cadaveric Study

PURPOSE

To determine whether a 5-mm and/or 10-mm arthroscopic lateral acromioplasty (ALA) would weaken the structural and mechanical integrity of the lateral deltoid.

METHODS

The acromion and lateral deltoid origin were harvested from 15 pairs (n = 30) of fresh-frozen human cadaveric shoulder specimens. One side of each specimen pair (left or right) was randomly assigned to either a 5-mm (n = 7) or 10-mm (n = 8) ALA group, and the contralateral sides (n = 15) were used as matched controls. Acromion thickness and width were measured pre- and postoperatively. After ALA, specimens were inspected for damage to the lateral deltoid origin. Each specimen was secured within a dynamic testing machine, and the deltoid muscle was pulled to failure. Statistical analysis was performed to determine whether ALA reduced the lateral deltoid's failure load.

RESULTS

There was no significant difference in failure load between the 5-mm ALA group (661 ± 207 N) and its matched control group (744 ± 212 N; mean difference = 83 N; 95% confidence interval [CI], -91 to 258; P = .285) nor between the 10-mm ALA group (544 ± 210 N) and its matched control group (598 ± 157 N; mean difference = 54 N; 95% CI, -141 to 250; P = .532). There was no correlation found between the amount of bone resected (measured by percent thickness and width of the acromion after ALA) and the failure load of the deltoid. Visual evaluation of the acromion after ALA revealed the lateral deltoid origin had no damage in any case.

CONCLUSIONS

ALA did not weaken the structural or mechanical integrity of the lateral deltoid origin. Neither a 5-mm nor a 10-mm ALA significantly reduced the deltoid's failure load. The lateral deltoid origin was not macroscopically damaged in any case.

CLINICAL RELEVANCE

ALA can be performed without the potential risk of macroscopically damaging the lateral deltoid origin or reducing its failure load.

Evaluation of Repair Tension in Arthroscopic Rotator Cuff Repair: Does It Really Matter to the Integrity of the Rotator Cuff?

BACKGROUND

Repair tension of a torn rotator cuff can affect healing after repair. However, a measurement of the actual tension during arthroscopic rotator cuff repair is not feasible. The relationship between repair tension and healing of a rotator cuff repair remains unclear.

PURPOSE/HYPOTHESIS

The purpose of this study was to evaluate the effect of repair tension on healing at the repair site. The hypothesis was that repair tension would be a major factor in determining the anatomic outcome of rotator cuff repair.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Arthroscopic rotator cuff repairs (132 patients) for full-thickness rotator cuff tears were analyzed. An intraoperative model was designed for the estimation of repair tension using a tensiometer. Magnetic resonance imaging (MRI) was performed approximately 1 year (mean [±SD], 12.7 ± 3.2 months) postoperatively for the evaluation of healing at the repair site. Multivariable analysis was performed for tear size, amount of retraction, and fatty degeneration (FD) of rotator cuff muscles.

RESULTS

The mean repair tension measured during the arthroscopic procedure was 28.5 ± 23.1 N. There was a statistically significant correlation between tension and tear size (Pearson correlation coefficient [PCC], 0.529; P < .001), amount of retraction (PCC, 0.619; P < .001), and FD of the supraspinatus (Spearman correlation coefficient [SCC], 0.308; P < .001) and infraspinatus (SCC, 0.332; P < .001). At the final follow-up (12.7 ± 3.2 months), healing failure was observed in 18.2% (24/132), and repair tension also showed a significant inverse correlation with healing at the repair site (SCC, 0.195; P = .025). However, when sex, age, tear size, amount of retraction, tendon quality, and FD of rotator cuff muscles were included for multivariable logistic regression analysis, only FD of the infraspinatus showed an association with the anatomic outcome of repair (Exp(B) = 0.596; P = .010).

CONCLUSION

Our intraoperative model for the estimation of rotator cuff repair tension showed an inverse correlation of repair tension with healing at the repair site, suggesting that complete healing is less likely with high-tension repairs. A significant association was observed on MRI between a high level of FD of the infraspinatus and repaired tendon integrity.

Editorial Commentary: Is Lateral Acromioplasty Effective and Safe?

Reduction of critical shoulder angle to less than 35° is potentially useful to prevent progression of rotator cuff tear or to protect cuff repair from re-tear. Lateral acromioplasty is an effective procedure to reduce the critical shoulder angle without violating the acromial deltoid origin.