Relationship between acromial morphological variation and subacromial impingement: A three-dimensional analysis

Transcending Patient Morphometry: Acromiohumeral Interval to Glenoid Ratio as a Universal Diagnostic Tool for Massive Rotator Cuff Tears

Background

Morphological differences among various ethnicities can significantly impact the reliability of acromiohumeral interval (AHI) measurements in diagnosing massive rotator cuff tears. This variation raises questions about the generalizability of AHI studies conducted in Western populations to the Asian population. Consequently, the primary objective of this study was to develop a novel parameter that can enhance the diagnosis of massive rotator cuff tears, irrespective of morphometric disparities between individuals of different ethnic backgrounds.

Methods

A 10-year retrospective analysis of shoulder arthroscopic surgery patients was conducted, categorizing them into 3 groups based on intraoperative findings: those without rotator cuff tears, those with non-massive tears, and those with massive tears. AHI-glenoid ratio (AHIGR) was measured by individuals with varying academic backgrounds, and its diagnostic performance was compared to AHI. Sensitivity, specificity, accuracy, and intra- and inter-rater reliability were evaluated.

Results

AHIGR exhibited significantly improved sensitivity, specificity, and accuracy as a diagnostic tool for massive rotator cuff tears, compared to AHI. A proposed cut-off point of AHIGR ≤ 0.2 yielded comparable results to AHI < 7 mm. Intra- and inter-rater reliability was excellent among different observers.

Conclusions

AHIGR emerges as a promising diagnostic tool for massive rotator cuff tears, offering improved sensitivity and specificity compared to AHI. Its reproducibility among diverse observers underscores its potential clinical utility. While further research with larger and more diverse patient cohorts is necessary, AHIGR offers significant potential as a reference for enhancing the assessment of massive rotator cuff tears.

Scapular morphology does not predict supraspinatus tendon tear propagation following an individualised exercise therapy programme

Purpose

To determine whether scapular morphology could predict isolated supraspinatus tendon tear propagation after exercise therapy. We hypothesised that a larger critical shoulder angle (CSA) and type III acromial morphology predict a positive change in tear size.

Methods

Fifty-nine individuals aged 40-70 years with isolated symptomatic high-grade partial or full-thickness supraspinatus tendon tears were included. Individuals participated in a structured, individualised 12-week exercise therapy programme and underwent ultrasound to measure tear size at baseline and 12 months following therapy. Computed tomography images were segmented to create three-dimensional subject-specific bone models and reviewed by three trained clinicians to measure CSA and to determine acromion morphology based on the Bigliani classification. A binary logistic regression was performed to determine the predictive value of CSA and acromion morphology on tear propagation.

Results

The CSA was 30.0 ± 5.4°. Thirty-one individuals (52.5%) had type II acromial morphology, followed by type III and type I morphologies (25.4% and 22.0%, respectively); 81.4% experienced no change in tear size, four (6.8%) individuals experienced tear propagation and seven (11.9%) individuals had a negative change in tear size. No significant difference in tear propagation rates based on CSA or acromion morphology (not significant [NS]) was observed. The model predicted tear size status in 81.4% of cases but only predicted tear propagation 8.3% of the time. Overall, CSA and acromion morphology only predicted 24.3% (R 2 = 0.243) of variance in tear propagation (NS).

Conclusions

CSA and acromion morphology were NS predictors of tear propagation of the supraspinatus tendon 12 months following an individualised exercise therapy programme.

Level of Evidence

II.

A Biological Spacer to Treat Irreparable Rotator Cuff Tears: A Biomechanical Study Utilizing a Secured Versus Unsecured Tensor Fascia Lata Graft

BACKGROUND

Designed to help treat pain and loss of function after rotator cuff repair, allograft spacer procedures utilize a graft to act as a spacer in the subacromial space, decreasing pain from impingement of the greater tuberosity on the acromion at the extremes of overhead motion.

PURPOSE

To evaluate the biomechanical characteristics of secured versus unsecured tensor fascia lata allografts used in an allograft spacer procedure.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 8 fresh-frozen cadaveric shoulder specimens were used. There were 4 conditions tested: (1) intact rotator cuff, (2) stage III rotator cuff tear (complete supraspinatus tendon and superior one-half of the infraspinatus tendon), (3) unsecured tensor fascia lata graft, and (4) secured tensor fascia lata graft. Both superior and posterior translation of the humeral head were calculated in each condition. A 4-cm × 5-cm × 6-mm tensor fascia lata graft was used in the subacromial space to act as a spacer. Grafts were secured at the lateral edge of the native rotator cuff footprint with 2 knotless anchors.

RESULTS

With unbalanced loading, both secured and unsecured grafts varied in their ability to limit superior and posterior translation at various rotation angles back to levels seen with intact rotator cuffs at 0° and 20° of abduction. During balanced loading, both unsecured and secured grafts limited superior and posterior translation more than those seen in the rotator cuff-deficient condition (P < .01) and similar to those seen in the intact condition (P > .05). The secured and unsecured grafts allowed similar amounts of translation at every position with both unbalanced and balanced loading (P > .05). Finally, total graft motion was <7 mm in all positions.

CONCLUSION

Unsecured tensor fascia lata grafts were biomechanically equivalent to secured grafts when used during allograft spacer procedures.

CLINICAL RELEVANCE

While both grafts were successful at limiting superior and posterior translation of the humeral head during early range of motion, the unsecured graft represents a cheaper, easier option to utilize during allograft spacer procedures.

The Correlation between Various Shoulder Anatomical Indices on X-Ray and Subacromial Impingement and Morphology of Rotator Cuff Tears

OBJECTIVES

Rotator cuff injury caused by subacromial impingement presents different morphologies. This study aims to investigate the correlation between various shoulder anatomical indexes on X-ray with subacromial impingement and morphology of rotator cuff tears to facilitate surgical management.

METHOD

This retrospective study was carried out between January 2020 and May 2022. Patients who were diagnosed as sub-acromial impingement associated with rotator cuff tears (without tendon retraction) and received arthroscopic surgery were enrolled in this study. The radiographic indexes of acromial slope (AS), acromial tilt (AT), lateral acromial angle (LAA), acromial Index (AI), and sub-acromial distance (SAD) were measured on preoperative true AP view and outlet view. The location of rotator cuff tear (anterior, middle, posterior, medial, and lateral) and morphology of tear (horizontal, longitudinal, L-shaped, and irregular shaped) were evaluated by arthroscopy. Groups were set up due to different tear location and tear morphologies, by comparing the various radiographic indices between each group (one-way analysis of variance and t-test), the correlation between radiographic indices and tear characteristics was investigated.

RESULTS

We analyzed 92 shoulders from 92 patients with a mean age of 57.23 ± 8.45 years. The AS in anterior tear group (29.32 ± 6.91°) was significantly larger than that in middle tear group (18.41 ± 6.13°) (p = 0.000) and posterior tear group (24.01 ± 7.69°) (p = 0.041). The AS in posterior tear group (24.01 ± 7.69°) was significantly larger than that in middle tear group (18.41 ± 6.13°) (p = 0.029). The LAA in middle tear group (67.41 ± 6.54°) was significantly smaller than that in posterior group (72.74 ± 8.78°) (p = 0.046). The AS in longitudinal tear group (26.86 ± 8.41°) was significantly larger than that in horizontal tear group (22.05 ± 9.47°) (p = 0.035) and L-shaped group (21.56 ± 6.62°) (p = 0.032). The LAA in horizontal group (70.60 ± 6.50°) was significantly larger than that in L-shaped group (66.39 ± 7.31°) (p = 0.033). The AI in L-shaped tear group (0.832 ± 0.074) was significantly larger than that in horizontal tear group (0.780 ± 0.084) (p = 0.019) and irregular tear group (0.781 ± 0.068) (p = 0.047).

CONCLUSION

Acromion with a larger AS and a smaller LAA tend to cause anterior or posterior rotator cuff tears rather than middle tears in sub-acromial impingement. Meanwhile acromion with a larger AS tends to cause a longitudinal tear, a larger LAA tends to cause horizontal tears and a larger AI tends to cause L-shaped tears.

Load-Induced Glenohumeral Translation After Rotator Cuff Tears: Protocol for an In Vivo Study

BACKGROUND

Rotator cuff tears are a common shoulder injury, but they sometimes remain undiagnosed, as symptoms can be limited. Altered shoulder biomechanics can lead to secondary damage and degeneration. In biomechanical analyses, the shoulder (ie, the glenohumeral joint) is normally idealized as a ball-and-socket joint, even though a translation is often observed clinically. To date, no conclusive changes in glenohumeral translation have been reported in patients with rotator cuff tears, and it is unknown how an additional handheld weight that is comparable to those used during daily activities will affect glenohumeral translations in patients with rotator cuff tears.

OBJECTIVE

This study aims to assess the load-induced glenohumeral translation (liTr) in patients with rotator cuff tears and its association with the load-induced changes in muscle activation (liMA).

METHODS

Patients and asymptomatic controls will be recruited. Participants will fill out health questionnaires and perform 30° arm abduction and adduction trials, during which they will hold different handheld weights of a maximum of 4 kg while motion capture and electromyographic data are collected. In addition, fluoroscopic images of the shoulders will be taken for the same movements. Isometric shoulder muscle strength for abduction and rotation will be assessed with a dynamometer. Finally, shoulder magnetic resonance images will be acquired to assess muscle status and injury presence. The dose-response relationship between additional weight, liTr, and liMA will be evaluated.

RESULTS

Recruitment and data collection began in May 2021, and they will last until the recruitment target is achieved. Data collection is expected to be completed by the end of 2022. As of November 2022, data processing and analysis are in progress, and the first results are expected to be submitted for publication in 2023.

CONCLUSIONS

This study will aid our understanding of biological variations in liTr, the influence of disease pathology on liTr, the potential compensation of rotator cuff tears by muscle activation and size, and the association between liTr and patient outcomes. The outcomes will be relevant for diagnosis, treatment, and rehabilitation planning in patients with rotator cuff tears.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04819724; https://clinicaltrials.gov/ct2/show/NCT04819724.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/43769.

How much acromial bone should be removed to decrease the critical shoulder angle? A 3D CT acromioplasty planning study

BACKGROUND

A high critical shoulder angle (CSA) is associated with rotator cuff tear (RCT) and retear rate after repair. CSA reduced to less than 33° by acromioplasty is correlated with better clinical results and healing. But up to 24% of patients retain a CSA above 35° after acromioplasty. The objective of the study was to evaluate the use of 3D when planning acromioplasty and measure acromial bone removal volume dimensions.

METHODS

Computed tomography (CT) scans from 45 patients with RCT and CSA ≥ 38° were retrospectively included. A 33° CSA cutting plane was positioned. Acromion was divided into 5 mm slices and acromial bone resection measured on each slice.

RESULTS

Intra- and inter-observer reproducibility measurements were rated strong or very strong. Patients' mean preoperative CSA was 40° (38°, 49° ± 2.3°). Measurements of acromial resection were: anteroposterior length: 32.7 mm (20, 50 ± 7.4); inferior width: 7.6 mm (4.2, 19 ± 2.9); superior width: 4.1 mm (0, 16 ± 3.0); height: 6.1 mm (1.7, 6.7 ± 1.6); and cutting angle: 74° (46, 91 ± 8.0). Maximum width of acromial resection was located 10.6 mm (5, 17.5 ± 0.6) from the acromion's anterior edge and decreased gradually moving posteriorly. Preoperative CSA was linearly correlated with width (P < 0.0001, R = 84%) and length (P = 0.0001, R = 28%) of acromioplasty; the higher the CSA, the greater the width and length.

CONCLUSIONS

3D CT reconstructions are valid for planning a CSA decreasing acromioplasty. To reduce CSA to 33°, acromioplasty must be performed anterolaterally and resection is at least 2 cm long anteroposteriorly. For higher CSAs, acromioplasty may require lateral resection over 1 cm in width and up to 5 cm in length. To decrease the CSA efficiently, acromioplasty must be adapted to patient anatomy and 3D planning could be considered.

LEVEL OF EVIDENCE

IV.

Bilateral coracohumeral distance discrepancy is associated with subscapularis tear in rotator cuff rupture patients

PURPOSE

To describe the bilateral coracohumeral morphological discrepancy in rotator cuff rupture patients with and without subscapularis (SSC) involvement and to investigate its association with SSC tears.

METHODS

Two hundred and thirteen consecutive patients who were scheduled to have arthroscopic rotator cuff repair were prospectively enrolled in the current study. Patients with acute traumatic rotator cuff rupture, glenohumeral osteoarthritis, bilateral rotator cuff rupture, recurrent shoulder instability, systemic inflammatory disease, and previous shoulder surgery history were excluded. Coracohumeral distance (CHD), coracoid overlap (CO), lesser tuberosity index (LTI) and acromiohumeral interval (AHI) were measured bilaterally using CT scans. Based on arthroscopic findings, patients were included in either the SSC tear group (n = 72) or the control group (n = 141).

RESULTS

In the SSC tear group, the affected shoulder possessed a significantly smaller CHD [95% confidence interval (CI) 6.1-7.2 vs. 7.2-8.0 mm, p < 0.0001], larger LTI (95% CI 9.4-9.9 vs. 9.0-9.6 mm, p < 0.0001), and smaller AHI (95% CI 5.0-5.5 vs. 7.1-7.5 mm, p < 0.0001) than the contralateral normal shoulder. In the control group, there was no significant difference between bilateral CHD and CO, and the AHI bilateral discrepancy was less distinct. CO did not differ significantly in the bilateral comparison in either group. Among all evaluated parameters, bilateral CHD discrepancy was the best predictor of SSC tears, with an area under the curve (AUC) of 0.882. A cutoff value of 0.5 mm had a sensitivity of 76.4% and specificity of 99.3% for SSC tears.

CONCLUSION

The CHD values are significantly different between affected and contralateral shoulders in SSC tear patients. Bilateral CHD discrepancy is closely associated with subcoracoid impingement and SSC tears, and its presence warrants specific intraoperative SSC inspection.

LEVEL OF EVIDENCE

Level II.

Is shoulder geometry important for rotator cuff tears?

PURPOSE

This study is aiming to evaluate some specific anatomic shoulder parameters such as the lateral acromial angle (LAA), acromial index (AI), coracohumeral distance (CHD) and critical shoulder angle (CSA) in rotator cuff tears.

METHODS

A total of 100 cases consisting of 50 patients with rotator cuff tears and 50 patients without rotator cuff tears, who underwent shoulder MRI (mangnetic resonance imaging) examination in Istanbul Medipol University Orthopedics and Traumatology Department, participated in this study. In this retrospective study, CCA, LAA, AI and CSA were evaluated in MRI in order to shed light on the theories of rotator cuff tears.

RESULTS

There was no significant difference (P ˃ .05) in acromial index and coracohumeral distance in the patient group. Lateral acromial angle and critical shoulder angle were significantly different in the patient group compared to the control group (P < .05). There was a weak negative correlation between CSA and CHD.

CONCLUSION

In our study, we found that patients with smaller LAA and higher CSA values in MRI images are prone to have rotator cuff tears. Further studies are needed in order to evaluate whether this association has predictive value.

A lower critical coracoid process angle is associated with type-B osteoarthritis: a radiological study of normal and diseased shoulders

Background

Degenerative rotator cuff tears and osteoarthritis (OA) are associated with differences in coronal plane scapular morphology, with particular focus on the effect of the critical shoulder angle (CSA) on shoulder biomechanics. The effect, if any, of axial plane scapular morphology is less well established. We have noticed wide disparity of axial coracoid tip position in relation to the face of the glenoid and sought to investigate the significance of this through measurement of the critical coracoid process angle (CCPA), which incorporates coracoid tip position and glenoid version.

Methods

CCPA, CSA, and glenoid retroversion were measured by three independent reviewers from the cross-sectional two-dimensional computed tomography (CT) and magnetic resonance imaging of 160 patients in four equal and matched case-control groups: (1) a control group of patients with a radiologically normal shoulder and no history of shoulder symptoms who had a CT thorax for another reason, (2) patients with primary OA with Walch type-A glenoid wear pattern on CT scan, (3) patients with type-B glenoid primary OA, and (4) patients with magnetic resonance imaging–proven atraumatic tears of the posterosuperior rotator cuff.

Results

Interobserver agreement was excellent for all measured parameters. The median CCPA was significantly lower in the type-B OA group (9.3˚) than that in controls (18.7˚), but not significantly different in the other study groups. There was a trend toward greater glenoid retroversion in the type-B OA group, but receiver operating characteristic curve analysis demonstrated the CCPA to be by far the most powerful discriminator for type-B OA. The optimal cutoff value was calculated for the CCPA at 14.3˚ with a sensitivity of 93% and specificity of 90% for type-B OA. Compared with controls, the CSA was significantly higher in the rotator cuff tear group and lower in both OA groups, but did not differentiate between type-A and type-B OA.

Conclusion

Combined with a lower CSA, a lower CCPA (<14.3˚) is strongly predictive of type-B glenoid OA. The authors propose a simple model of pectoralis major biomechanics to explain the effect of this axial plane anatomical variation, which requires further investigation.

Evaluation of critical shoulder angle and acromion index in patients with anterior shoulder instability and rotator cuff tear

OBJECTIVE

The aim of this study was to evaluate glenohumeral morphologic differences and their correlation between glenohumeral instability and rotator cuff pathology.

METHODS

Two-hundred radiographs and 100 MRI scans of 100 patients in whom the diagnosis of Anterior Shoulder Instability (Anl) or Rotator Cuff Tear (RCT) was arthroscopically verified were retrospectively identified and included in the study. All the patients were categorized into two groups: 50 patients with Anl (23 female, 28 male; mean age = 29 ± 7.4) and 50 patients with RCT (28 female, 22 male). Two separate control groups were then formed, one of which included contralateral shoulders of patients in the AnI group, and the other consisted of contralateral shoulders of patients in the RCT group. The x-ray and MRI scans were examined by an orthopedic surgeon and a radiologist. The Acromial Index (AI) and the Critical Shoulder Angle (CSA) were measured on true anteroposterior shoulder radiographs; Glenoid Inclination (GI), Glenoid Version (GV), and Acromion Angulation (AA) were measured on MRI.

RESULTS

In the AnI group, the measurements were as followed: AI, 0.66 ± 0.03; CSA, 33 ° ± 2.85; GI, 3.4° ± 6.2; GV, 4.1 ± 4.3; and AA, 12.9 ± 8.3. In the RCT group, AI 0.71 ± 0.04; CSA, 36° ± 2.69; GI, 9.1 ± 5; GV, 6.7 ° ± 5.7; and AA, 14.3° ± 8.7. A moderate correlation was found between CSA and GI (r = 0.41, P = 0.001) and between AI and GI (r = 0.42, P = 0.014). A weak correlation was found between AI and GI in the AnI group (r = 0.22, P = 0.001). The inter- and intra-observer intraclass correlation coefficients were respectively 0.81 and 0.84 for AI, 0.88 and 0.92 for CSA, 0.72 and 0.76 for GI, 0.69 and 0.73 for GV, and 0.72 and 0.77 for AA.

CONCLUSION

The results of this study have shown that lower AI, GI, and antevert GV may be associated with AnI. Investigating CSA, AI, and GV could be useful for diagnostic evaluation of patients with AnI.

LEVEL OF EVIDENCE

Level III, Diagnostic Study.

Palmitic acid promotes resistin-induced insulin resistance and inflammation in SH-SY5Y human neuroblastoma

Saturated fatty acids such as palmitic acid promote inflammation and insulin resistance in peripheral tissues, contrasting with the protective action of polyunsaturated fatty acids such docosahexaenoic acid. Palmitic acid effects have been in part attributed to its potential action through Toll-like receptor 4. Beside, resistin, an adipokine, also promotes inflammation and insulin resistance via TLR4. In the brain, palmitic acid and resistin trigger neuroinflammation and insulin resistance, but their link at the neuronal level is unknown. Using human SH-SY5Yneuroblastoma cell line we show that palmitic acid treatment impaired insulin-dependent Akt and Erk phosphorylation whereas DHA preserved insulin action. Palmitic acid up-regulated TLR4 as well as pro-inflammatory cytokines IL6 and TNFα contrasting with DHA effect. Similarly to palmitic acid, resistin treatment induced the up-regulation of IL6 and TNFα as well as NFκB activation. Importantly, palmitic acid potentiated the resistin-dependent NFkB activation whereas DHA abolished it. The recruitment of TLR4 to membrane lipid rafts was increased by palmitic acid treatment; this is concomitant with the augmentation of resistin-induced TLR4/MYD88/TIRAP complex formation mandatory for TLR4 signaling. In conclusion, palmitic acid increased TLR4 expression promoting resistin signaling through TLR4 up-regulation and its recruitment to membrane lipid rafts.

Acromial morphology and morphometry associated with subacromial impingement syndrome

Acromion is a major associated structure of subacromial impingement syndrome, one of the most common diagnoses in chronic shoulder pain world-wide. The aims of this study are to study morphometry of acromion and to find risk group using acromial morphometry. Total samples were 392 scapulae. The samples were of both sexes, ranging from the age of 31 to 90. Acromion type and osteophytes were observed. Acromial parameters were measured. The relationships were analyzed among acromion type, acromial osteophyte, acromial parameters, age group, sex and side. Curved acromion had the highest prevalence in all age groups. Hooked acromion had the second highest prevalence since the age of 41. Hooked acromion prevalence was higher in male than in female. The highest prevalence of acromial osteophytes was on anteroinferior surface in all age group. The prevalence of acromial osteophytes on anteroinferior surface and acromial facet increased with age. In addition, acromion type was associated with only osteophytes on anteroinferior surface of acromion. Anterior one-third acromial thickness in the age of 31 to 50 was different from those of 51 to 90. There are differences between all parameters and sexes, but not side. General population with age above 50 and concerned male group with age above 40 who have chronic shoulder pain should be investigated for subacromial impingement syndrome. Surgical treatment is recommended because hooked acromion and osteophytes are mostly the root of problem.

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

Background

The 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.

Methods

A 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.

Discussion

This 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 registration

ChiCTR2000032343. Registered on April 26th, 2020.

Feasibility of the acromion index as a reference of severity of stratified supraspinatus tendon injury: a secondary analysis

BACKGROUND

The acromion index (AI) is the acromial lateral extension above the head of the humerus. Some researchers have advocated that the AI indicates the severity of the tear size of the full-thickness supraspinatus tendon.

PURPOSE

To validate the reproducibility of the AI between shoulder magnetic resonance imaging (MRI) and standard X-ray and to verify whether the AI is a useful index for stratifying the severity of supraspinatus tendon injuries, as well as full-thickness tears.

MATERIAL AND METHODS

We enrolled 200 patients with impingement syndrome who were subsequently evaluated with standard X-ray of the shoulder in the anteroposterior view, as well as an MRI. We performed a pilot study to validate the reproducibility of the AI using standard X-ray and MRI, and to compare the AI between these imaging modalities. The severity of supraspinatus tendon injury was classified into four groups (0 = no evidence of injury, 1 = partial tear, 2 = full-thickness tear, and 3 = complete rupture) based on an official reading of the shoulder MRI. We compared the AIs of both modalities between the groups.

RESULTS

Intraclass correlation coefficients of the AIs between the two examiners were 0.819 for MRI and 0.808 for plain X-ray. The mean AI from standard X-ray was greater than that from MRI (P<0.0001). There was no statistical correlation between the AI and the severity of supraspinatus tendon injury.

CONCLUSION

Our findings indicate that the AI cannot be generally used as a predictive reference for the stratified severities of supraspinatus tendon injury.

Prediction of Rotator Cuff Injury Associated with Acromial Morphology: A Three-Dimensional Measurement Study

Objective

To analyze the relationship between the acromial morphology and the related rotator cuff injury using a three‐dimensional (3D) measurement technology.

Methods

For the present study, 226 patients (113 men and 113 women) who underwent shoulder Coarthroscopy from June 2015 to December 2019 at the Department of Orthopedics at our hospital were selected retrospectively. A total of 113 shoulder joints of age‐matched healthy people were selected as the control group. A 3D model coordinate system of the shoulder was established based on CT scan images. Patients were grouped according to the condition of the rotator cuff injury during surgery. The patients whose rotator cuff tear site corresponded to the 3D osseous proliferative structure of the acromion were classified into the impingement injury group (II group). The other patients were classified into the non‐impingement injury group (NII group). The acromiohumeral interval (AHI), the acromial anterior protrusion (AAP), the acromial inferior protrusion (AIP), the acromioclavicular angle (AC angle), the distance from the most medial edge of the acromial anterolateral protrusion (AALP) to the most lateral point of acromion (MLPA) (a), the distance from the most posteromedial edge of the AALP to the MLPA (b), the anteroposterior diameters of the AALP (c), and the proportion of anteroposterior diameters of AALP to the anteroposterior diameters of acromion, (c/c + d) × 100(%), were measured using the 3D shoulder model.

Results

The results of the intraobserver (<5%) and interobserver variability (>87%) analysis found the parameters to have high intraobserver and interobserver concordance. There were no significant differences in age among the control group, the NII group, and the II group (P = 0.8416). There were significant differences in AAP among the three groups (P = 0.0374). The results were the same for men and women, respectively. The AAP in the control group and the NII group did not show a difference, while the AAP in the II group was increased by 26.9% (P = 0.015) and 25% (P = 0.023), respectively, compared with the NII group and the control group. AHI, AIP, and AC angles did not show significant differences among the three groups (P > 0.05). The (a) and (b) of the II group were significantly larger than those of the NII group; P‐values were 0.0119 and 0.0003, respectively. The (a) and (b) in patients with rotator cuff injuries were larger than in the normal population (P < 0.05). The above results were the same for men and women. This suggested that the larger width of the AALP might cause the related rotator cuff injury. The (c/c + d) in the II group was significantly larger than those in the control and the NII groups, with P‐values of 0.0005 and 0.0021, respectively. The risk of rotator cuff injury due to subacromial impingement was increased when the maximum width of the medial–lateral edge of the AALP exceeded 16.8 mm (17.4 mm in men, 15.1 mm in women), the maximum width of the posterior edge of the AALP exceeded 12.9 mm (13.8 mm in men,12.7 mm in women), or the anteroposterior diameters of the AALP exceeded the anteroposterior diameters of the acromion by 33.5%.

Conclusion

We could predict the occurrence and development of the related rotator cuff injury in symptomatic patients with specific 3D changes in their acromion and intervene in the acromion of such patients as early as possible to prevent possible rotator cuff injuries in the future.

Evaluation of three-dimensional acromiohumeral distance in the standing position and comparison with its conventional measuring methods

Background

Narrowing of the acromiohumeral distance (AHD) implies a rotator cuff tear. However, conventional AHD measurements using two-dimensional (2D) imaging or with the patient in the supine position might differ from that while standing during daily activity. This study aimed to evaluate the three-dimensional (3D) actual distance between the acromion and humeral head in the standing position and compare the AHD values with those obtained using conventional measuring methods.

Methods

Computed tomography (CT) images of 166 shoulders from 83 healthy volunteers (31 male and 52 female; mean age 40.1 ± 5.8 years; age range, 30–49 years) were prospectively acquired in the supine and standing positions using conventional and upright CT scanners, respectively. The minimum distance between the acromion and humeral head on the 3D surface models was considered as the 3D AHD. We measured the 2D AHD on anteroposterior digitally reconstructed radiographs. The AHD values were compared between the supine and standing positions and between the 2D and 3D measurements.

Results

The mean values of 2D AHD were 8.8 ± 1.3 mm (range, 5.9–15.4 mm) in the standing position and 8.1 ± 1.2 mm (range, 5.3–14.3 mm) in the supine position. The mean values of 3D AHD were 7.3 ± 1.4 mm (range, 4.7–14.0 mm) in the standing position and 6.6 ± 1.2 mm (range, 4.4–13.7 mm) in the supine position. The values of 3D AHD were significantly lower than those of 2D AHDs in both the standing and supine positions (P < 0.001). The values of 2D and 3D AHDs were significantly lower in the supine position than in the standing position (P < 0.001).

Conclusions

This study evaluated the 3D AHD of normal shoulders in the standing position using an upright CT scanner. The present results indicated that assessments in the supine position can underestimate the value of the AHD compared with those made in the standing position and that assessments using 2D analysis can overestimate the value.

Reduced acromiohumeral distance and increased critical shoulder angle: implications for primary care clinicians

Objectives: The literature indicates that reduced acromiohumeral distance (AHD) and increased critical shoulder angle (CSA) are associated with large and massive rotator cuff (RC) tears which may not be amenable to a successful repair. The purpose of this study was to examine the overall accuracy of these two radiographic features in diagnosing significant RC pathology. Methods: This was a diagnostic study of patients with shoulder pain. To examine the overall accuracy of the measurements, the area under the Receiver Operating Characteristic curves (AUC) were calculated. The validity indices (sensitivity, specificity and likelihood ratios) examined the predictive value of specific cutoff categories of AHD<6 mm and the CSA >35°. Results: Data of 200 consecutive patients; mean age: 59(11), 117 males were used for analysis. There was a weak inverse correlation (r = 0.46) between the AHD and CSA. The AUCs for presence and size of RC tear and different stages of fatty infiltration of supraspinatus and infraspinatus muscles varied from fair to excellent for AHD and poor to good for CSA. Specificity was high for the cutoff categories of both AHD and CSA (>90%). The positive LRs were large for AHD and small to moderate for CSA. Conclusion: The AHD and CSA were reliably measured in the true AP radiographic view. Both radiographic features (AHD<6mm and CSA>35°) were able to confirm the presence of a major RC pathology. However, the AHD<6 mm, an acquired radiologic abnormality secondary to failure of the RC muscles/tendons had better measurement properties. This information is of value to primary care physicians, sports medicine specialists and advanced practice physiotherapists in their clinical decision making.

Evaluation of the cross-sectional area of acromion process for shoulder impingement syndrome

Background

Anatomic changes in the acromion have been considered a main cause of shoulder impingement syndrome (SIS). To evaluate the relationship between SIS and the acromion process, we devised a new morphological parameter called the acromion process cross-sectional area (APA). We hypothesized that the APA could be an important morphologic diagnostic parameter in SIS.

Methods

We collected APA data from 95 patients with SIS and 126 control subjects who underwent shoulder magnetic resonance imaging (MRI). Then we measured the maximal cross-sectional area of the bone margin of the acromion process on MRI scans.

Results

The mean of APAs were 136.50 ± 21.75 mm² in the male control group and 202.91 ± 31.78 mm² in the male SIS group; SIS patients had significantly greater APAs (P < 0.001). The average of APAs were 105.38 ± 19.07 mm² in the female control group and 147.62 ± 22.90 mm² in the female SIS group, and the SIS patients had significantly greater APAs (P < 0.001). The optimal APA cut-off in the male group was 165.14 mm² with 90.2% sensitivity, 91.4% specificity, and an area under the curve (AUC) of 0.968. In the female group, the optimal cut-off was 122.50 mm² with 85.2% sensitivity, 84.9% specificity, and an AUC of 0.928.

Conclusions

The newly devised APA is a sensitive parameter for assessing SIS; greater APA is associated with a higher possibility of SIS. We think that this result will be helpful for the diagnosis of SIS.

Anatomic shoulder parameters and their relationship to the presence of degenerative rotator cuff tears and glenohumeral osteoarthritis: a systematic review and meta-analysis

BACKGROUND

Scapular anatomy, as measured by the acromial index (AI), critical shoulder angle (CSA), lateral acromial angle (LAA), and glenoid inclination (GI), has emerged as a possible contributor to the development of degenerative shoulder conditions such as rotator cuff tears and glenohumeral osteoarthritis. The purpose of this study was to investigate the published literature on influences of scapular morphology on the development of degenerative shoulder conditions.

METHODS

A systematic review of the Embase and PubMed databases was performed to identify published studies on the potential influence of scapular bony morphology on the development of degenerative rotator cuff tears and glenohumeral osteoarthritis. The studies were reviewed by 2 authors. The findings were summarized for various anatomic parameters. A meta-analysis was completed for parameters reported in more than 5 related publications.

RESULTS

A total of 660 unique titles and 55 potentially relevant abstracts were reviewed with 30 published articles identified for inclusion. The AI, CSA, LAA, and GI were the most commonly reported bony measurements. Increased CSA and AI correlated with rotator cuff tears, whereas lower CSA appeared to be related to the presence of glenohumeral osteoarthritis. Decreased LAA correlated with degenerative rotator cuff tears. Five articles reported on the GI with mixed results on shoulder pathology.

DISCUSSION

Degenerative rotator cuff tears appear to be significantly associated with the AI, CSA, and LAA. There does not appear to be a significant relationship between the included shoulder parameters and the development of osteoarthritis.

Correlation of acromial morphology in association with rotator cuff tear: a retrospective study

Purpose

There have been many studies that have attempted to correlate radiographic acromial characteristics with rotator cuff tears, but the results have not been conclusive. Rotator cuff tears (RCT) are the common aetiology of shoulder pain. We assessed the association of rotator cuff tears with commonly used radiographic parameters of acromial morphology and their different radiographic characteristics.

Material and methods

From a retrospective study of 98 patients, we characterised acromial type and measured acromial thickness (AT), critical shoulder angle (CSA), lateral acromial angle (LAA), acromiohumeral distance (AHD), and acromion index (AI) on a 1.5T MRI, from 68 patients with partial or full-thickness supraspinatus tendon tears and 30 controls without tears.

Results

Out the 68 patients with rotator cuff tear, supraspinatus was the most commonly affected tendon, with 86% (59) cases showing abnormalities. The average age of the patients was 45.11 ± 21.45 years with male dominance (80%). Partial tears of rotator cuff were more common than complete tears. Forty-eight cases showed partial tears in supraspinatus as compared to 11 cases of complete tears. The acromial type did not show any correlation with any particular cuff lesion. The AT and AI of controls were significantly smaller than cuff-tear patients. The LAA of cuff-tear patients was significantly different from that of control patients. The impingement patients demonstrated a significantly greater acromial thickness, larger CSA, decreased AHD, and decreased LAA than their control counterparts.

Conclusions

A higher prevalence of rotator cuff tears and impingement associated with low lateral acromial angle, larger CSA and decreased AHD was observed. AT and AI have a direct correlation with rotator cuff tear.

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.

Correction between the Morphology of Acromion and Acromial Angle in Chinese Population: A Study on 292 Scapulas

Introduction. The acromion is a small section of the scapula which extends anteriorly from the spine of the scapula and the acromial angle (AA) is a prominent bony point at the junction of the lateral border of the acromion and the spine of the shoulder blade. As is well known, the morphology of the acromion and the acromial angle are important as their anatomical variation may contribute to shoulder pathologies. However, few people have studied the morphology and the association between the acromion and the acromial angle. The study explores the acromion and the acromial angle in the anatomical morphology and the association, providing an anatomical basis for clinical diagnosis and treatment. Material and Methods. A total of 292 dry, intact scapulae (152 right, 140 left) were used in the study. Three types of the acromion were already measured, type I(flat shape), type II (curved shape), and type III (hooked shape), respectively. Three types of the acromial angles were also measured in this study, C shape, L shape, and Double Angle shape. Results. The research result shows that C shape and L shape were the most common, while Double Angle shape was the least common. C shape was often related to type I (flat shape) and L shape was often related to type II (curved shape). Conclusions. The presented data provides precise and well-sorted information about the acromion and the acromial angle variation in Chinese population, contributing to diagnosis and treating in shoulder pathology.