Lateral Acromioplasty Research Articles

Predictability and functional impact of lateral acromioplasty using preoperative 2D planning on the correction of the critical shoulder angle (CSA) in patients with rotator cuff repair

Rotator cuff tears are highly prevalent, and their association with critical shoulder angle (CSA) has been reported. There is controversy regarding whether the morphology of the acromion influences its incidence, as well as whether acromioplasty would impact the results of a rotator cuff repair. Lateral acromioplasty does not play a decompressive role; rather, it aims to correct the deltoid vector. According to some publications, this would achieve less loading on the repaired rotator cuff, a lower retear rate, and better function. CSA correction with lateral acromioplasty can be planned with radiography (2-dimensional [2D]), but its predictability has not been fully studied. The primary objective of this study is to evaluate the predictability of 2D planning with radiography in CSA correction in patients with rotator cuff repair. The secondary objective is to analyze the association between the correction of the CSA and the functional outcomes. This single-center, prospective, observational, analytical study included candidates for arthroscopic repair of a rotator cuff tear with a CSA > 35°. Lateral acromioplasty was performed as planned with preoperative radiography (2D) to achieve a CSA of 35°. The degrees to be corrected were calculated. CSA was recalculated with a postoperative radiography; and the error in the planned grades to be corrected was calculated. At the end of follow-up, Visual Analog Scale, Subjective Shoulder Value (SSV), and Quick-Disabilities of the Arm, Shoulder, and Hand (Quick-DASH) scores were evaluated. Forty one cases were included, 43.9% were men, and the mean age was 55.5±8.6 years. The mean preoperative and postoperative CSA were 39.6°±1.9° and 35.7°±2.3°, respectively; 41.5% achieved a postoperative CSA ≤ 35°. The mean CSA planned correction error was 45.7±28.8%. At the end of the follow-up, 33 (78.6%) had a functional evaluation, with an average follow-up of 41±6.8 months. The mean Visual Analog Scale, Quick-DASH, and SSV were 0.9±1.6, 5.3±7.5, and 92.7±10.6, respectively. There was a significant difference in Quick-DASH (P=.01) and SSV (P=.02) according to whether a postoperative CSA ≤ 35° was achieved. In lateral acromioplasty, planning of CSA correction with radiography (2D) is imprecise. Reaching a CSA ≤ 35° positively influences functional results.

Computer Image-Guided Precise Acromioplasty for Reducing the Critical Shoulder Angle

The shoulders with critical shoulder angle (CSA) of greater than 33-35° are associated with rotator cuff tears, whereas a CSA of less than 30° is likely to be osteoarthritic. However, anterior acromioplasty or lateral acromioplasty could not reduce high CSAs to the desired range (30-33°), with satisfactory accuracy and efficacy. Thus, we introduce a computer image-guided precise acromioplasty (CIG-PAP) technique, an individualized treatment based on three-dimensional planning. We believe that the introduction of this technique will provide an alternative approach to reduce a large CSA to the desired range (30-33°).

Radiographs Are Comparable With 3-Dimensional Computed Tomography-Based Models as a Modality for the Preoperative Planning of the Arthroscopic Lateral Acromioplasty: A Retrospective Comparative Study

PurposeTo compare plain radiographs with 3-dimensional (3D) computed tomography (CT) data for preoperative planning of arthroscopic lateral acromioplasty (ALA) for patients in whom ALA was performed along with arthroscopic rotator cuff repair (ARCR).MethodsPatients older than 25 years old who underwent ALA along with ARCR in our institution between October 2019 and February 2021 were included in this study. Preoperative ALA simulations were performed on plain radiographs and 3D models based on CT data. The critical shoulder angle (CSA) was compared between simulations based on radiographs and those based on 3D models. The ALA procedure was performed using the 3D model simulation, along with ARCR. The CSA after surgery was investigated using radiographs.ResultsWe evaluated 11 shoulders in 10 patients. There was no significant difference between the mean preoperative CSA on radiographs and 3D models (38.0° ± 2.6° vs 38.6° ± 1.8°, respectively; P = .55). The mean CSA after 4-mm ALA simulation using radiographs was not significantly different to that using 3D models (34.1° ± 2.6° vs 34.3° ± 2.5°, respectively; P = .84). Four cases (36.4%) required 8-mm ALA to reduce the CSA to <35° on radiographic analysis, and 2 (18.2%) required 8-mm ALA on 3D model analysis. The mean CSA on postoperative radiographs was significantly smaller than that on preoperative radiographs (32.1° ± 2.7° vs 38.0° ± 2.6°, respectively; P < .01).ConclusionsThere was no significant difference between the mean CSA after a 4-mm ALA simulation using radiographs and that using 3D models based on preoperative CT data, which suggests that radiographs are comparable with 3D CT data models as a reliable modality for the preoperative simulation of ALA.Level of EvidenceIII, retrospective comparative study.

Lateral Acromioplasty With the Aim of Reducing the Critical Shoulder Angle Using Techniques Based on the Lateral Acromial Border Result in Larger-Than-Necessary Resections

PurposeTo compare the axial plane orientation and width and length of the acromial resections required to reduce the critical shoulder angle (CSA) using lateral acromioplasty (LA) techniques that are based on the lateral acromial border with an ideal resection that is oriented parallel to the glenoid. MethodsThis was a retrospective observational cohort study of symptomatic patients that were investigated for shoulder pain, instability, or fracture with high-quality computed tomography (CT). The CT scan data were used to create 3-dimensional meshes, and a series of LA resection planes were mapped. The orientation, width, and length of each resection based on the lateral acromial border (lateral, anterolateral, posterolateral, and image guided) to reduce the measured CSA to 35° or 30° was compared with an ideal resection that was oriented parallel to the glenoid. Results23 models had CSA 30.1° to 35°, and 13 had CSA >35°. In the models with CSA >35°, there was no angular difference between the resection planes of the lateral, anterolateral, or image-guided resections compared with the ideal technique; there were differences in the required width and length of the resections to reduce the CSA to 35° (additional width/length: lateral, 3.2/14.8 mm; anterolateral, 2.8/10.6 mm; posterolateral, 6.9/19.2 mm; image guided, 2.4/10.3 mm). Width and length differences were also present in the models with CSA >30° when the resections aimed to reduce the CSA to 30° (additional width/length: lateral, 2.5/12.5 mm; anterolateral, 1.9/8.8 mm; posterolateral, 7.4/19.0 mm; image guided, 1.6/8.8 mm). ConclusionsLA techniques based on the lateral acromial border did not replicate the ideal resection and may lead to excessive deltoid release which could adversely affect clinical results. Clinical relevanceOur findings do not support LA techniques based on the lateral acromial border.

Correction of the CSA does not decrease the re-tear rate after SSP repair

Abstract Background The re-tear rate after supraspinatus tendon (SSP) repair is high despite optimization of surgical techniques. The critical shoulder angle (CSA) &gt; 35° has been identified as a risk for re-tear. Surgical reduction of the CSA performing additional lateral acromioplasty (ALAP) is intended to reduce the risk. Objective We aimed to evaluate the effect of ALAP on the re-tear rate in patients with a CSA &gt; 35° after SSP repair. Patients and methods The study included 49 shoulders fulfilling predefined inclusion criteria. The patients were assigned to two groups; group I (25 SSP) was additionally treated with an ALAP. In group II (24 SSP) standard acromioplasty was performed during reconstruction. Magnetic resonance imaging and a clinical examination (Constant Score; CS) were performed 12 months after surgery. Results After 15 months group I showed a re-tear rate of 20%, a decreased CSA (mean 38.0° preoperatively vs. 34.5° postoperatively) and an increase in CS (mean 53.9 vs. 84.6). After 16 months group II showed a re-tear rate of 16.7%, no difference between pre- and postoperative CSA (37.8° vs. 37.6°), and an increase in CS (48.9 vs. 84.5). There was no difference between the groups in terms of re-tears and postoperative CS (p = 0.4557), but there was a significant difference in postoperative CSA (p &lt; 0.0001). We did not find a decrease in the failure rate after ALAP. Unlike other studies, patients with a postoperative CSA &gt; 35° did not have a worse clinical outcome and no increased rate of re-tears compared with patients with a mechanically reduced CSA. Conclusion Additive lateral acromioplasty does not decrease the re-tear rate after arthroscopic SSP repair. However, ALAP significantly decreases the CSA to normal values.

Influence of Radiographic Parameters on Reduction of the Critical Shoulder Angle With Arthroscopic Lateral Acromioplasty—A Mathematical Model

ObjectivesTo develop a mathematical model for the preoperative planning of arthroscopic lateral acromioplasty (ALA) and to evaluate the role of radiographic parameters with regards to the critical shoulder angle (CSA).MethodsAnteroposterior (AP) radiographs of patients who underwent rotator cuff surgery were screened to identify true AP radiographs. Radiographs were assessed for (1) native CSA, (2) CSA after simulated resection of a spur if present, (3) amount of ALA necessary to achieve a CSA of 34°, (4) CSA after 5-mm ALA, (5) lateral acromion angle, (6) acromion index, and (7) sclerosis of the greater tuberosity.ResultsA total of 1191 radiographs were screened. Of the 124 patients included, the native CSA was large (≥35°) in 56 patients (45%). In 30 patients (24%), a subacromial spur was detected and resection reduced the CSA by a median of 2°. Spur resection alone reduced the CSA to ≤34° in 19 patients (15.3%). Mean amount of ALA to achieve a CSA of 34° was 3.9 ± 1.8 mm, and this value strongly correlated with the CSA before ALA (R = 0.88, P < .001). The linear regression model to determine the amount of ALA to achieve a CSA of 34° was as follows: The multiple R2 for this model was 0.777. Mean reduction of CSA by 5-mm ALA was 3.8 ± 0.8° and 75% of large CSAs were reduced to a CSA of 30-34°. The acromion index had no significant independent influence on the model (P = .427), whereas lateral acromion angle was an independently significant predictor of required ALA to achieve a CSA of 34° (P = .019). Sclerosis of the greater tuberosity was significantly associated with a CSA of 35° or greater (P = .003).ConclusionsThe amount of ALA needed to reduce a large CSA to 34° correlates with the CSA before ALA and can preoperatively be planned with the use of a simple equation.Level of EvidenceLevel III; cross-sectional design; epidemiology study.

Lateral Acromioplasty has a Positive Impact on Rotator Cuff Repair in Patients with a Critical Shoulder Angle Greater than 35 Degrees.

Background: A Critical Shoulder Angle (CSA), evaluated on plain radiographs, greater than 35° is considered predictive of rotator cuff tears. The present prospective comparative study aimed, firstly, to develop a formula to calculate the amount of acromion that should be resected performing a lateral acromioplasty and, secondly, verify whether lateral acromioplasty to reduce the CSA associated with arthroscopic cuff repair decreased the rate of recurrence of the tears, and impacted favorably on clinical postoperative outcomes. Methods: Patients undergoing arthroscopic rotator cuff repair (RCR) for rotator cuff tears with a CSA greater than 35° were included in this study and divided into two groups, based on whether the CSA had been reduced by arthroscopic resection of the lateral portion of the acromion. A new mathematical formula was developed in order to quantify the amount of bone to be resected while performing the lateral acromioplasty. Patients with traumatic tears, previous surgery, osteoarthritis or plain radiographs, not classified as A1 according to Suter-Henninger, were excluded. Clinical and radiographic outcomes were assessed at a minimum of 2 years of follow-up considering the tear size. Results: 289 patients were included in this study. Thirty-seven were lost to follow-up. Group A (Lateral acromioplasty) patients included: 38 small tears, 30 medium tears, 28 large tears and 22 massive tears; Group B (control group) was composed of 40 small tears, 30 medium tears, 30 large tears and 23 massive tears. The Constants Score value and retear Rate were, respectively, significant higher (p = 0.007 and p = 0.004) and lower (p = 0.029 and p = 0.028) in Group A, both in the Small-and Medium-size subgroups. No complications were outlined. The mediolateral width of the acromion was reduced, according to the preoperatively calculated measure. Conclusion: Arthroscopic lateral acromioplasty decreased the CSA within the favorable range (30°–35°) in all patients treated, resecting the amount of bone predicted by the mathematical formula. Lateral acromioplasty is a safe and reproducible technique which may prevent recurrence of rotator cuff tears in patients with small and medium lesions. Level of evidence: II.

Effect of arthroscopic acromioplasty on reducing critical shoulder angle: a protocol for a prospective randomized clinical trial

BackgroundThe critical shoulder angle (CSA), which helps to predict patients who are at risk of rotator cuff tears (RCTs) with large degree and who are susceptible to osteoarthritis with low angle, has been identified as one of the most vital acromial parameters; anterolateral and lateral acromioplasties have been proven to be valid ways to reduce CSA. However, no study has compared the effect of different acromioplasties on the reduction of the large CSA (≥33°) clinically. Additionally, either anterolateral or lateral acromioplasty could not precisely correct large CSAs to a favorable range (30–33°) in each patient. Thus, we will propose a novel precise acromioplasty technique for the purpose of reducing CSA accurately and effectively, and compare the effectiveness of different acromioplasties on the reduction of the CSA.MethodsA total of 60 RCT patients who have indications for arthroscopic rotator cuff repair and with pre-operative CSA ≥33° will be recruited in outpatient center of Sun Yat-sen Memorial Hospital. Eligible participants will be randomly allocated to Group A (anterolateral acromioplasty), Group B (lateral acromioplasty) or Group C (precise acromioplasty) via a random, computer-generated number system. Three surgical plans will be made for each participant respectively by one professional surgeon according to the results of randomization allocation. The post-operative CSA will be measured 2 days post-operation. Follow-up will be maintained at 3, 6, and 12 months after surgery including the visual analog scale score, the University of California at Los Angeles score, the Constant Shoulder Score and the American Shoulder and Elbow Surgeon Shoulder Assessment Form. Finally, all outcomes will be assessed by two researchers who are blinded to the recruitment and allocation.DiscussionThis is the first clinical trial to evaluate the impact of different acromioplasties on the reduction of the CSA. Additionally, this study will provide a new precise acromioplasty technique, which is a novel precision and individualized treatment to prevent degenerative RCTs by reducing the CSA.Trial registrationChiCTR2000032343. Registered on April 26th, 2020.

The Lateral Deltoid Originates From the Entire Lateral Wall of the Acromion: MRI and Histologic Cadaveric Analysis Regarding Vertical Lateral Acromioplasty

PurposeThe aim of this study was to assess the nature of the middle deltoid muscle insertion onto the lateral acromion by macroscopic, MRI and histologic examination and to, therefore, assess the potential impact of a vertical lateral acromioplasty on the deltoid origin.MethodsWe assessed the acromial origin of the deltoid in 6 cadaver shoulders by macroscopic, MRI and histologic examination. The cadavers were scanned with T1 and proton density-weighted sequences. H&E- and Masson trichrome-stained histologic sections through the acromion were taken and visualized under polarized microscopy.ResultsThe enthesis of the deltoid muscle consisted of dense birefringent bundles of collagen that blended with the bony endplate of the acromion at all points on its lateral wall. A prominent band of collagen was seen on both MRI and histologic slices, traversing the superior surface of the acromion. It was continuous with the deltoid origin and blended with the superficial fascia of the deltoid laterally.ConclusionsThe middle deltoid muscle occupies the entire lateral acromion.Clinical RelevanceA high critical shoulder angle is associated with rotator cuff tears. A lateral acromioplasty resects the lateral acromion and aims to normalize the critical shoulder angle. However, a vertical lateral acromioplasty may release the middle deltoid origin from the lateral acromion. The superior band of collagen may anchor the middle deltoid to the superior acromion and prevent retraction.

Lateral acromioplasty for correction of the critical shoulder angle

AbstractThe critical shoulder angle (CSA) was introduced as a radiological parameter associated with a higher incidence of rotator cuff tears. As a logical consequence, correcting the CSA together with rotator cuff repair should prevent re-tear and provide reliable and good clinical results. We present an all-arthroscopic technique resecting the lateral edge of the acromion (lateral acromioplasty) in order to reduce and correct the CSA after preoperative planning. Preliminary results from 20 patients with an average age of 62 years after rotator cuff repair are reported showing good clinical outcome with a Constant score of 88 points and no re-tear after an average follow-up of 16 months. The CSA was reduced from 39.7° to 32.1°. Previous concerns regarding weakening of the deltoid origin were not confirmed and there were no complications linked to lateral acromioplasty.

Acromial morphology is not associated with rotator cuff tearing or repair healing

The purposes of this study were to determine whether acromial morphology (1) could be measured accurately on magnetic resonance images (MRIs) as compared to computed tomographs (CTs) as a gold standard, (2) could be measured reliably on MRIs, (3) differed between patients with rotator cuff tears (RCTs) and those without evidence of RCTsor glenohumeral osteoarthritis, and (4) differed between patients with rotator cuff repairs (RCRs) that healed and those that did not. This is a retrospective comparative study. We measured coronal, axial, and sagittal acromial tilt; acromial width, acromial anterior and posterior coverage, and glenoid version and inclination on MRI corrected into the plane of the glenoid. We determined accuracy by comparison with CT via intraclass correlation coefficients (ICCs). To determine reliability, these same measurements were made on MRI by 2 observers and ICCs calculated. We compared these measurements between patients with a full-thickness RCT and patients aged >50 years without evidence of an RCT or glenohumeral osteoarthritis. We then compared these measurements between those patients with healed RCRs and those with a retorn rotator cuff on MRI. In this portion, we only included patients with both a preoperative MRIand a postoperative MRI at least 1 year from RCR. Only those patients without tendon defects on postoperative MRIs were considered to be healed. In these patients, we also radiographically measured the critical shoulder angle. In a validation cohort of 30 patients with MRI and CT, all ICCs were greater than 0.86. In these patients, the inter-rater ICCs of the MRI measurements were >0.53. In our RCT group of 110 patients, there was greater acromial width [mean difference (95% confidence interval) = 0.1 (0, 0.2) mm, P = .012] and significantly less sagittal acromial tilt [9° (5°-12°), P < .001] than in our comparison group of 107 patients. A total of 110 RCRs were included. Postoperative MRI scans were obtained at a mean follow-up of 24.2 ± 15.8 months, showing 84 patients (76%) had healed RCRs. Aside from acromial width, which was 0.2 mm different and thus did not have clinical significance, there was no association between healing and any of the measured morphologic characteristics. Patients with healed repairs had significantly smaller tears in terms of both width (P < .001) and retraction (P < .001). Although the acromion is wider in RCTs, the difference of 0.1 mm likely has no clinical significance. The acromion is more steeply sloped from posteroinferior to anterosuperior in those with RCTs. These findings call into question subacromial impingement due to native acromial morphology as a cause of rotator cuff tearing. Acromial morphology, critical shoulder angle, and glenoid inclination were not associated with healing after RCR. This study does not support lateral acromioplasty.

Lateral acromioplasty cannot sufficiently reduce the critical shoulder angle if preoperatively measured over 40°.

To investigate whether arthroscopic lateral acromion resection can sufficiently reduce the critical shoulder angle (CSA) without damaging deltoid muscle insertion. Ninety patients who underwent arthroscopic rotator cuff (RC) repair were retrospectively analysed. According to the preoperative CSA, patients were categorized as Group I (CSA < 35°) and Group II (CSA ≥ 35°). Additional arthroscopic lateral acromion resection was performed in Group II. The CSA was measured 1week postoperatively, while RC integrity and the deltoid attachment were assessed at 3, 6 and 12months via ultrasound. Deltoid function was evaluated using the Akimbo test, in which patients place their hands on the iliac crest with abduction in the coronal plane and internal rotation of the shoulder joint while simultaneously flexing the elbow joint and pronating the forearm. Large and massive RC tears were more prevalent in Group II (p = 0.017). In both groups, the CSA reduction was statistically significant (Group I = 1°: range 0°-3°, Group II = 3.7°: range 1°-8°; p < 0.001). When the preoperative CSA was > 40°, the respective postoperative CSA remained > 35° in 83.3% of cases (p < 0.001). Final shoulder strength was correlated with the amount of CSA reduction (rho = 0.41, p = 0.002). The postoperative CSA was higher, but not significantly different (n.s.), in patients with re-torn (36°, range 32°-40°) than with healed RC (33°, range 26°-38°). No clinical detachment or hypotrophy of the deltoid was observed with the Akimbo test and ultrasound evaluation. Arthroscopic lateral acromion resection is a safe procedure without affecting deltoid muscle origin or function, and it is effective in significantly reducing the CSA. However, the CSA cannot always be reduced to < 35°, especially in patients with preoperative CSA values > 40°. III.

Indications and techniques of arthroscopic anterior and lateral acromioplasty

Arthroscopic anterior acromioplasty (AAAP) for treatment of symptomatic subacromial spur. Arthroscopic lateral acromioplasty (ALAP) to reduce apathological critical shoulder angle (CSA) and prevent rotator cuff re-tear after reconstruction. 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. 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. 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 arotator cuff-tear is followed by reduction of apathologically increased CSA by resection of the lateral edge of the acromion. After isolated AAAP, physiotherapy can be performed without restriction. After AAAP or ALAP combined with rotator cuff repair, immobilization in abrace is recommended. The use of pain medication should be standardized and adapted to individual pain levels.

Influence of the site of acromioplasty on reduction of the critical shoulder angle (CSA) \u2013 an anatomical study

BackgroundA 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.MethodsFirst, 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.ResultsScapular 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.ConclusionsFor 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.

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

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. 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 12months' follow-up. We reviewed 49 consecutive patients (mean age, 56years; age range, 39-76years) at a mean of 30months (range, 12-47months). 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). 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 IV, case series, treatment study.

The Critical Shoulder Angle is Associated with Osteoarthritis in the Shoulder but Not Rotator Cuff Tears. A Retrospective Case Control Study

This study is the first study with a methodological strength (case-control study) that allows for vague causal claims concerning the association between CSA, RCT and OA. The results indicate that lateral acromioplasty might be harmful. 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 of the shoulder (OA). The purpose of the study was to test if the CSA was associated with RCT and OA. The study hypothesis being that people having a CSA > 35° were at increased risk of developing RCT and people with a CSA < 30° were at increased risk of developing OA. The study was performed as a retrospective case- control study following the STROBE guidelines. 97 patients with RCT and 87 patients with OA constituted the two groups of cases. 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. in 2013. Sample size calculation showed a need for 71 cases and 213 controls. 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. The mean CSA in the RCT group was 33.9° and in the matched control group 33.6°. 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). This study is the first study with a methodological strength that allows for vague causal claims concerning the association between CSA, RCT and OA. No causal relationship was found between CSA and RCT but between CSA and OA with a 2.25 Odds Ratio of developing OA given the patient had a CSA below 30°. The results does not support the suggested praxis of lateral acromioplasty as it might increase the risk of developing OA without decreasing the risk of developing RCT.

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

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. 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. There was no significant difference in failure load between the 5-mm ALA group (661 ± 207N) and its matched control group (744 ± 212N; mean difference= 83N; 95% confidence interval [CI], -91 to 258; P= .285) nor between the 10-mm ALA group (544 ± 210N) and its matched control group (598 ±157N; mean difference= 54N; 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. 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. ALA can be performed without the potential risk of macroscopically damaging the lateral deltoid origin or reducing its failure load.

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

To investigate if (1) an anterolateral acromioplasty and (2) a lateral acromion resection alter the critical shoulder angle (CSA) without affecting the deltoid origin. First, the native CSAs of 10 human cadaveric shoulders (6 male and 4 female specimens; mean age, 54.2 years) were determined with the use of fluoroscopy. Setup allowed for consistent repetitive measurements. Next, a standard arthroscopic anterolateral acromioplasty was performed to create a type 1 acromion, and the CSA was reassessed fluoroscopically. Afterward, a lateral acromioplasty was performed with a 5-mm lateral acromion resection using a 5-mm burr, and the CSA was measured again. The native CSA was compared with (1) the CSA after acromioplasty and (2) the CSA after acromioplasty and lateral acromion resection using a paired t test. Finally, the acromial deltoid attachment was evaluated anatomically for damage to the anterolateral origin. The mean native CSA (34.3° ± 2.1°) was reduced significantly by acromioplasty (33.1° ± 2.0°, P < .001) and further reduced by lateral acromion resection (31.5° ± 1.7°, P < .001). Anterolateral acromioplasty reduced the CSA by a mean of 1.4° (95% confidence interval boundaries, 0.8° and 1.9°), and in combination with lateral acromion resection, the CSA was reduced by a mean of 2.8° (95% confidence interval boundaries, 2.1° and 3.5°). In all specimens (5 of 5) with a presurgery CSA of 35° or greater, the CSA was reduced to the range of 30° to 35° by the combination of both techniques. However, in 2 specimens with a CSA of approximately 32°, the CSA was reduced to less than 30°. The acromial deltoid attachment was found to be well preserved in all specimens. Arthroscopic anterolateral acromioplasty and a 5-mm lateral acromion resection each reduced the CSA significantly and did not damage the deltoid origin. The combination of both techniques could potentially be used in clinical practice to reduce a CSA greater than 35° to the desired range of 30° to 35°.

Limited Lateral Acromioplasty for Rotator Cuff Surgery

This article describes a modified technique for acromioplasty performed during rotator cuff repair.

けん板断裂例における肩峰の形態と画像所見の対比

In 1986, Bigliani studied the relationship between the shape of the acromion and rotator cufftears. He reported that a higher incidence of rotator cuff tears results in a hooked type acromion. The aim of this study is to investigate the relationship between the morphology of the acromion obtained at surgery with that of the pre-operative MR image and Scapular Y view.56 patients with an average age of 56 years were operated on, pre-operating MR imaging was carried out in 47 cases and Scapular Y view was in 43 cases. The acromion was obtained at surgery by lateral acromioplasty. The acromion was sliced into a thickness of 100μ and it was classified as flat (type 1), smoothly curved (type 2), or hooked (type 3) according to Bigliani's classification. Scapular Y view was taken with a X-ray fluoroscopy so that the undersurface of the acromion could be observed and classified into three groups. The acrominal shape of MRI imaging was classified from the sagital oblique gradient echo images, and Scapular Y view were obtained and classified into the same classification.Specimens type 1, type 2 and type 3 were 19.6%, 48.2% and 32.1% respectively. The accurancy of MRI image and Scapular Y view were 51.1% and 37.2%. In this study, no higher incidence of rotator cufftears was found in hooked type acromion, but there was a difference between the acrominal type in MRI imaging, Scapular Y view and that of specimens.