Rotator Cuff Tear Group Research Articles

Can a high acromion index predict rotator cuff tears?

The purpose of this study was to identify the relationship between an acromion index (AI) and the size of a rotator cuff tear. The hypothesis of our study was that an AI will be higher in patients with a full-thickness tear than in patients with a partial-thickness articular-side tear, and that it can be used as a predictor for the size of a rotator cuff tear. We included 284 patients who had been diagnosed with rotator cuff tears and had undergone arthroscopic rotator cuff repair at our institute. All patients were divided into five distinct groups (partial-thickness articular side tear, and four subgroups of full-thickness tears) depending on the size of the rotator cuff tear on arthroscopy. In each patient, an AI was measured on the pre-operative oblique coronal MR images and then analysed to determine the difference between groups. There were statistically significant differences between the partial-thickness articular side rotator cuff tear and large-to-massive rotator cuff tear groups (p < 0.01), and the mean value of an AI was highest in the large-sized full-thickness tear group. The AI of the partial-thickness articular-side rotator cuff tear group was statistically different from the large-to-massive rotator cuff tear groups. The AI can be a predictor which can differentiate a partial-thickness articular-side tear and a large-to-massive rotator cuff tear pre-operatively. However the AI could not provide useful guidance on predicting the differences in tear size in full-thickness tear patients. We suggest that a high AI can be one of the associated factors for progression to large-to-massive rotator cuff tears in a rotator cuff disease.

Intraarticular lesions in calcifying tendinitis: incidence and association with the acromion index

Intraarticular pathologies are a common finding during arthroscopy for rotator cuff lesions. Both rotator cuff tears as well as cartilage lesions have been described as correlating with the acromion index. In the current study, we aimed to determine the incidence of intraarticular lesions in calcifying tendinitis, to compare the incidence in patients with partial- and full-thickness tears of the rotator cuff, and to determine the acromion index in these groups. The incidence and type of accompanying intraarticular lesions were compared between three consecutive, age-matched groups of 64 patients each: those with calcifying tendinitis (group A), and those with partial- (group B) and full-thickness rotator cuff tears (group C). Also, the acromion index was measured from plain radiographs and compared between the groups. The incidence of intraarticular pathology was 43% in group A, 41% in group B and 84% in group C. The differences between groups A and C as well as B and C were significant (p<0.0001), but not between groups A and B (p=0.858). Even though the acromion index was larger in group C than in the other two groups, the difference was not significant (A vs. B, p=0.505; A vs. C, p=0.180; and B vs. C p=0.446). The incidence and type of intraarticular lesions in calcifying tendinitis are comparable to age-matched shoulders with partial- rather than full-thickness rotator cuff tears. The acromion index is not different between shoulders with calcifying tendinitis, and partial- or full-thickness rotator cuff tears.

1, 2단계 충돌 증후군과 회전근 개 파열 환자의 등속성 근력 비교

Purpose: The goal of this study was to evaluate differences in strength deficits between (i) patients with stage 1 or 2 impingement syndrome and (ii) patients with rotator cuff tears. Materials and Methods: We enrolled 43 patients with stage 1 or 2 impingement syndrome (group 1) and 21 patients with rotator cuff tears (group 2). The isokinetic strength of both groups was evaluated at for external rotation, internal rotation, adduction and abduction. We measured the peak torque, total work, average power of bilateral sides, peak torque relationship to body weight, and the ratio between unilateral agonist and antagonist. Results: The isokinetic strength deficits assessed in ratio of peak torque to body weight for group 1 and group 2 respectively were; and for abduction (p

The Influence of the Acromioclavicular Joint Degeneration on Supraspinatus Outlet Impingement and the Acromion Shape

To assess the anatomic association of acromioclavicular joint degeneration to supraspinatus outlet impingement and the acromion shape. Sagittal oblique magnetic resonance images of 49 shoulders in 49 patients were reviewed. 29 of them (mean age, 59 years) underwent surgery for impingement with or without rotator cuff tear (group 1), whereas the 20 controls (mean age, 27 years) were treated for shoulder instability without rotator cuff disease or acromioclavicular joint derangement (group 2). The supraspinatus outlet and the acromion shape of the 2 groups were compared. The difference in the mean supraspinatus outlet between groups 1 and 2 was 11% (514 vs 577 mm[2], p=0.095) and between the subgroup (of group 1) with full thickness rotator cuff tears and group 2 was 17% (481 vs 577 mm[2], p=0.036). Six of the acromions in group 1 were type III (hooked) compared to none in group 2. In severe acromioclavicular degeneration, distal clavicular excision is recommended, even in cases with an asymptomatic acromioclavicular joint, so as to prevent further osteophyte formation.

Higher fasting plasma glucose levels within the normoglycaemic range and rotator cuff tears

Objective:To determine the plasma glucose levels in non-diabetic patients with rotator cuff tear.Design:Frequency-matched case–control study.Setting:University Teaching Hospital.Participants:The study included 194 subjects who were operated on at our institution. Group 1...

The Effect of the Acromion Shape on Rotator Cuff Tears

o, respectively, and the anterior covering of the acromion was measured to be 0.55±0.13 and 0.51±0.14, respectively. In a comparison with the control group of subjects, the lateral extension of the acrominon of the rotator cuff tear group of patients was larger and the lateral acromial angle was smaller; these findings were statistically significant (p＜0.001). In addition, the correlation coefficients of the lateral extension of the acromion to the lateral acromial angle in the rotator cuff tear group of patients and in the control group of subjects was −0.44 and −0.46, respectively; a statistically significant correlation was seeen (p＜0.001). Conclusion: The results suggest that the measurement of the lateral extension of the acromion and the lateral acromial angle determines the shape of the acromion, and thus it may represent a useful marker to confirm the interrelationship of a rotator cuff tear.

Shoulder Impingement: Objective 3D Shape Analysis of Acromial Morphologic Features

To retrospectively and quantitatively analyze the acromial undersurface in three dimensions and to determine its association with impingement syndrome and rotator cuff tears. Institutional review board approval was received with exemption of informed consent for this retrospective HIPAA-compliant study. Magnetic resonance images were evaluated in 84 patients (63 males, 21 females; mean age, 42.6 years; age range, 15-74 years). On the basis of surgical results, patients were separated into three groups: those without shoulder impingement or rotator cuff tears (31 patients), those with shoulder impingement (22 patients), and those with rotator cuff tears (31 patients). To quantitate the acromial undersurface, the structure was manually plotted, and a mathematic model was created by using splines. The undersurface was divided into a 20 x 20 grid. For each patient, a shape index (SI) data set and local undersurface angulation (LUA) data set were determined. Regression analyses were used to identify differences between groups, and prediction models were constructed on the basis of correspondent areas. Analysis of both data sets yielded no apparent progression between groups and demonstrated a lack of similarity between the impingement and rotator cuff tear groups. Discrimination between groups could be demonstrated by dividing the lateral portion of the acromial undersurface into contiguous blocks. The highest overall diagnostic accuracy of our prediction models was 58.3% (49 of 84) by using 10 blocks of the SI data set and 73.8% (62 of 84) by using five blocks of the LUA data set. Three-dimensional modeling yields objective data about the acromial undersurface. On the basis of this method, osseous impingement by the acromion is not a primary cause of shoulder impingement syndrome or rotator cuff tears.

Proinflammatory Cytokines and Metalloproteases Are Expressed in the Subacromial Bursa in Patients With Rotator Cuff Disease

The pathophysiology of subacromial impingement syndrome is poorly understood. We investigated the expression of inflammatory cytokines, metalloproteases, and the cyclooxygenases in the subacromial bursa in control patients and in patients with rotator cuff tear. Basic science evaluation. Eighteen patients undergoing shoulder surgery had a subacromial bursa biopsy examination. Patients were divided into 2 groups. Group I (study group) had 10 patients with a full-thickness rotator cuff tear (RCT). Group II (control group) had 8 patients. Seven of 8 underwent shoulder arthroscopy with anterior capsular reconstruction for instability; 1 of 8 underwent open reduction internal fixation for acute proximal humerus fracture. None of the patients in group II had any history of symptoms or signs consistent with subacromial impingement. H&E and immunohistochemical antibody (MMP-1, MMP-9, IL-1, IL-6, TNF-alpha, COX-1, and COX-2) stained specimens were examined by 2 blinded observers using a histologic scale (grade 0 = no staining to grade 4 = intense staining). Histologic evidence of inflammation was present in all patients with RCT (group I). No or mild inflammation was noted in group II. The average staining grade for inflammatory cytokines (IL-1, IL-6, TNF-alpha) and proteinases (MMP-1 and MMP-9) was significantly more pronounced in the RCT group (P < .001). Cyclooxygenase enzymes (COX-1 and COX-2) were also increased in group II (P < .001). A high level of expression of inflammatory cytokines, proteinases, and cyclooxygenase enzymes, known to produce a catabolic environment, is present in the subacromial bursa of patients with rotator cuff tear. These findings support the role of nonsteroidal anti-inflammatory drugs and corticosteroids in RCT treatment, and emphasize the importance of subacromial bursectomy to reduce inflammation in RCT surgery.

Effect of rotator cuff pathology on shoulder rhythm

The purpose of this study was to test the hypothesis that shoulder rhythm is affected by rotator cuff pathology during arm elevation. We divided 42 subjects into 3 groups: those with full-thickness rotator cuff tears (RCTs) (n = 14), those with tendinopathy (n = 13), and control subjects (n = 15). Shoulder kinematics was recorded while subjects performed elevation in the sagittal and scapular planes. Euler angles were computed for scapular and humeral elevation. Data were divided into 3 equal phases. Lines were fit and the slope determined for each phase. Significant differences in slopes ( P < .05) were found between experimental groups for both motions. The RCT group had higher slopes in the initial and middle phases for sagittal elevation and in the middle phase for scapular abduction. The scapula was elevated more in the RCT group in the initial two thirds of movement. This motion may change the length of remaining muscles so that they operate on a more effective part of their length-tension curve.

Comparative study of arthroscopic treatment of full-thickness rotator cuff tear with or without frozen shoulder (SS-77)

Purpose: To describe the comparative results of arthroscopic treatment of full-thickness rotator cuff tear with or without frozen shoulder. Materials and Methods: We evaluated thirty consecutive patients with isolated full-thickness rotator cuff tear (group A), and twenty consecutive patients with concomitant full-thickness rotator cuff tear and frozen shoulders (group B) for a mean of 2 years 6 months (range, 1 year to 5 years 11 months) following arthroscopic treatment. The clinical results were evaluated with the University of California at Los Angeles (UCLA) Shoulder Rating Scale. In group A, there were 11 men and 19 women with 25 dominant shoulders and in group B, 8 men and 12 women with 14 dominant shoulders. The average tear size was 24.5 ± 15.1 mm in group A, and 17.0 ± 13.0 mm in group B. In this study, severe arthritis in the acromioclavicular joint and the glenohumeral joint was excluded. Results: In group A, pain score was improved from 2.2 ± 1.2 before operation to 9.2 ± 1.2 after operation, function score, 4.1 ± 1.8 to 9.7 ± 0.7, forward flexion score, from 3.8 ± 1.3 to 5.0 ± 0.2 and strength score, from 4.3 ± 0.7 to 5.0, respectively. In group B, pain score was improved from 3.0 ± 1.5 to 9.2 ± 1.2, function score, from 4.3 ± 2.0 to 9.7 ± 0.7, forward flexion score, from 2.4 ± 0.7 to 5.0, and strength score, from 4.0 ± 0.8 to 5.0, respectively. In group B, forward flexion was improved from 86.0° ± 21.6° before operation to 173.5° ± 8.8° after operation, abduction, from 79.8° ± 32.7° to 173.0° ± 6.6°, external rotation, from 27.0° ± 12.6° to 55.3° ± 5.3°, respectively (P < .05). The UCLA Shoulder Rating Scale showed 93% good/excellent results in group A, and 95% in group B. There was no statistical difference of results in group A and B using paired t test. Conclusions: Arthroscopic management is an very effective treatment modality of full-thickness rotator cuff tear with or without frozen shoulder. For successful results, early mobilization and control of pain after operation as well as adequate arthroscopic procedures are critical.

Correlation between rotator cuff tear and glenohumeral degeneration.

We studied the occurrence and correlation between a rotator cuff tear and glenohumeral degeneration. 44 cadaveric shoulders (22 right) were obtained from 32 subjects (18 females), mean age 73 (62-86) years and without a history of systemic diseases. Rotator cuffs were exposed and tear size (14 shoulders) was measured after removal of soft tissue and deltoid. Articular cartilage damage of the glenoid and humeral head was recorded by photography. A grading system of 1 (intact), 2 (mild) and 3 (severe) was used to determine the severity of cartilage damage. The area of articular cartilage damage was calculated using the Sonic Digitizer Analyzing System. The area of articular cartilage damage to the glenoid and the humeral head in the rotator cuff tear group was 32% and 36%, respectively. It was greater than that in the groups without a tear, which was 6% in the glenoid and 7% in the humeral head. However, it was not correlated with the size of the tear. Most of the articular cartilage damage in massive and large rotator cuff tears was located in the anterior-inferior portion of the glenoid and in the posterior portion of the humeral head. The articular cartilage damage area of the glenoid was correlated with that of the humeral head. In conclusion, the area of glenohumeral degeneration was greater in the rotator cuff tear group and was located in a specific site.

Mini-open rotator cuff repair using a two-row fixation technique: Outcomes analysis in patients with small, moderate, and large rotator cuff tears

Mini-open rotator cuff repair has been used successfully to treat small- and moderate-sized rotator cuff tears but not large tears (>3cm and <5cm). We use a 2-row fixation technique of repairing the torn cuff to the humerus. We sought to determine if this technique would produce successful results in patients with larger rotator cuff tears. The results of 75 consecutive patients who underwent arthroscopic subacromial decompression with acromioplasty and mini-open rotator cuff repair were evaluated. All patients were evaluated at a minimum 24 months postoperatively (mean, 27 months). All patients were treated with a mini-open rotator cuff repair using a 2-row fixation technique. Patients were evaluated at follow-up with a focused shoulder examination, Hospital for Special Surgery (HSS) Shoulder Questionnaire, and the University of California Los Angeles (UCLA) Shoulder Rating Scale. There were 49 male and 26 female patients, with a mean age of 54 years (range, 34-72 years). All patients failed a preoperative course of physical therapy and nonoperative management. Thirty patients were found to have a large rotator cuff tear (group I), 35 were found to have a moderate-sized tear (group II), and 10 patients had a small tear (group III) at the time of arthroscopy. There was no statistically significant difference in outcome between groups. The mean UCLA Shoulder Rating Scale for all groups was 33.6/35. Mean HSS Shoulder Questionnaire at follow-up was 91%. The mean time from surgery to full recovery was 7 months. Patient’s subjective satisfaction based on their preinjury level of performance at most recent follow-up was 92.6%. Eighty-three percent (74/89) of patients returned to their preinjury activity; 93% of patients reported that they would undergo the procedure again. We believe that mini-open rotator cuff repair using a 2-row fixation technique can yield excellent results in patients with small, moderate, and large rotator cuff tears. There was no detectable difference in outcome between groups at 2-year follow-up on clinical evaluation.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 6 (July-August), 2002: pp 665–670

관절경적 회전근 개 봉합술 : 1 - 4년 추시 결과

Purpose : To compare and analyze the results of arthroscopic subacromial decompression and rotator cuff repair between partial rotator cuff tear and complete rotator cuff tear. Material and Methods : The authors studied 42 patients of rotator cuff tear with operation and followed over one year at Dankook university hospital from September, 1998 to March, 2001 The patient average age is 53 years and follow up period is 23 months (12-42mon1hs). We obtained 22 cases in the partial rotator cuff tear group and 20 cases in the complete rotator cuff tear group. In all cases, we used ASES methods to evaluated pain scale and function. Result : In the last follow up patients, the pain scale is decreased from 7.2 to 0.9 (ASES method : 34 to 91) in the partial rotator cuff tear group and from 7.6 to 1.2 (ASES method . 29 to 88) in the complete rotator cuff tear group, but there was no evidence of statistical difference between two groups (P>0.05). The range of motion after operation were increased in two groups. Excellent to good results were obtained 93％ and 95％ patients had pain relief and satisfied function. Conclusion : Arthroscopic subacromial decompression and arthroscopic rotator cuff repair showed good results for both of (ult-thickness and partial thickness rotator cuff tear patients in pain relief and improving the function.

Contact geometry at the undersurface of the acromion with and without a rotator cuff tear

Purpose: The purpose of this study was to investigate the difference in contact geometry at the undersurface of acromion in shoulders with and without a rotator cuff (RC) tear. Type of Study: Case-control study. Methods: Forty fresh cadaveric shoulders (average age at death, 61 years) without gross osteoarthritic changes were divided into the intact RC group (n = 20) and the RC tear group (n = 20). Clinical impingement was simulated by compressing the humeral head and the intact portion of the RC against the coracoacromial arch with an axial compressive force of 25 kg while the humerus was held abducted 20° in the scapular plane. The contact pattern between the acromion and the RC was measured with Fuji Prescale super low-pressure–sensitive film (Fuji Photo Film Co, Ltd, Tokyo, Japan). The imprint image was analyzed using Global Lab image software (Automatix, Marlboro, MA). Results: The percentage of the maximum anteroposterior dimension of the imprint on Fuji film to the anteroposterior diameter of the acromial undersurface was 29% ± 9% in intact RC shoulders, and 39% ± 13% in shoulders with an RC tear (P >.05). The percentage of the maximum mediolateral dimension of the imprint to the mediolateral diameter of the corresponding part of the acromial undersurface was 27% ± 12% in intact RC shoulders, and 48% ± 11% in shoulders with an RC tear. This difference was statistically significant (P <.005). Conclusions: The contact geometry of the acromial undersurface with the underlying RC in the anteroposterior dimension, which might be related to the appearance in supraspinatus outlet view, was not significantly different between shoulders with and without an RC tear. These findings suggest that factors other than acromial shape play a significant role in the pathogenesis of RC tears. The implication regarding the role of acromioplasty remains to be clarified.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 4 (April), 2001: pp 365–372

Quantitative analysis of neural distribution in human coracoacromial ligaments.

This study investigated sensory nerve distribution in 27 human coracoacromial ligaments by immunohistochemical methods using antiprotein gene product 9.5 antibody and anticalcitonin gene related peptide antibody. Mean nerve densities were compared among three areas (acromion side, center, and coracoid side) in two groups (patients with rotator cuff tears and patients with shoulder dislocations). In all three areas of both groups, many nerve fibers immunoreactive to antiprotein gene product 9.5 antibody were observed in the periligamentous bursal tissue. However, in the ligament parenchyma, nerve fibers immunoreactive to antiprotein gene product 9.5 antibody were recognized only around blood vessels. Nerve fibers immunoreactive to anticalcitonin gene related peptide antibody were recognized in the periligamentous bursal tissue. However, in the ligament parenchyma, there were no nerve fibers immunoreactive to anticalcitonin gene related peptide antibody. Nerve density of the rotator cuff tear group, as revealed by both immunostainings, showed a significant increase compared with that of the shoulder dislocation group in all three areas. The results of this study show that it is possible the increase in sensory nociceptive nerve fibers in the coracoacromial ligaments may be one of the causes for pain in patients with rotator cuff tears.

Glenohumeral motion in patients with rotator cuff tears: A comparison of asymptomatic and symptomatic shoulders

The purpose of this study was to determine whether there was a relationship between altered scapular plane glenohumeral kinematics end shoulder pain. Subjects were divided into 3 groups: normal volunteers (n = 10), patients with symptomatic rotator cuff tears severe enough to warrant surgery (n = 10), and subjects with no symptoms who had tears documented on magnetic resonance imaging and normal examination (n = 10). Humeral kinematics were observed with a computer-enhanced modification of the Poppen and Walker technique. Scapular plane x-ray films were obtained at 0 degree, 30 degrees, 60 degrees, 90 degrees, 120 degrees, and 150 degrees of elevation. Measurements were made by 3 independent observers blinded to the diagnosis, and data interpretation was performed based on mean values for independent observers. Results showed a high degree of interobserver and intraobserver reliability (coefficients = 0.96 and 0.95, respectively). The symptomatic and asymptomatic groups showed progressive superior translation of the humeral head on the glenoid with increasing arm elevation. The normal group, in contrast, maintained a constant center of rotation along the geometric center of the glenoid. Symptomatic and asymptomatic rotator cuff tear groups showed superior head migration from 30 degrees to 150 degrees, which was significantly different from those seen in the normal group. No significant difference between the symptomatic and asymptomatic groups was demonstrated with the small numbers used in this study. The presence of a rotator cuff tear was associated in a disruption of normal glenohumeral kinematics in the scapular plane. Because significant superior migration of the humeral head was seen in both the asymptomatic and symptomatic rotator cuff groups, painless and normal shoulder motion is possible in the presence of abnormal glenohumeral kinematics. Abnormal glenohumeral kinematics alone was not an independent factor, which could explain the occurrence of symptoms.

The influence of acromioclavicular joint morphology on rotator cuff tears

A detailed anatomic study of 123 shoulders was performed to define the location of the acromioclavicular (AC) joint within the supraspinatus outlet and to determine the correlation of AC joint morphologic characteristics with the presence of full-thickness rotator cuff tears (RCTs). The presence, location, and extent of RCTs were first documented for each shoulder, and 2 anatomic landmarks consisting of the anterolateral acromial corner and the inferior midpoint of the AC joint were identified and their positions digitized in 3 dimensions to calculate outlet space and clearance and AC joint locations. High resolution x-ray films were then obtained to determine the extent of degenerative changes including the location and size of inferior osteophytes and joint space. These specimens were cleaned of all soft tissues, and additional measurements were made. All data were entered into a computerized database and analyzed with respect to age, sex, and the presence of RCT. Comparison of age-matched RCT versus non-RCT groups revealed no significant differences in the position of the AC joint within the supraspinatus outlet. When AC joint morphologic characteristics were compared with those of a nontear, age-matched group, no significant differences with regard to joint space narrowing were found, but significantly larger and greater number of osteophytes were identified on both sides of the joint in the RCT group. In conclusion, the position of the AC joint is fairly constant within the supraspinatus outlet and does not appear to predispose to RCTs. The morphology of the AC joint contribution of the tears seems to be acquired in nature rather than inherent in its location within the outlet.

Shoulder kinematics with two-plane x-ray evaluation in patients with anterior instability or rotator cuff tearing

The goals of this study were to define biplanar glenohumeral kinematics and glenohumeral-scapulothoracic motion relationships in normal patients with a two-plane radiograph series and then in patients with anterior shoulder instability or rotator cuff tear both before surgery and after surgical repair and postoperative rehabilitation. A two-plane radiographic series of x-ray films in the scapular and horizontal (axillary) planes was performed. With these films, measurements of the relationship between the centers of the humeral head and glenoid and measurements of the component contributions of glenohumeral and scapulothoracic motion to total arm abduction were made. Six normal adults underwent x-ray evaluation to establish normal control values. Kappa analysis was used to determine reliability of technique. Eighteen patients with confirmed anterior shoulder instability (group A) and 15 with confirmed rotator cuff tears (group B) were studied before surgery. Seven (39%) of 18 of the patients in group A and all 15 (100%) of the patients in group B demonstrated superior translation of the humeral head during scapular plane abduction. In the horizontal plane 14 (78%) of 18 patients in group A (instability) and none in group B (rotator cuff tear) demonstrated abnormal anterior translation of the humeral head on the glenoid. Both groups demonstrated altered glenohumeral-scapulothoracic motion relationships compared with the normal control group. Two years after surgery 12 patients from group A and 14 patients from group B were restudied. All of these patients had demonstrated abnormalities of humeral head translation before surgery. For group A 12 (100%) of 12 patients demonstrated normal glenohumeral kinematics in both planes after open anterior stabilization. For group B 12 (86%) of 14 patients demonstrated normal glenohumeral kinematics in both planes after open rotator cuff repair. In group A the altered glenohumeral-scapulothoracic motion relationships persisted, whereas in group B these relationships became normal.

Radiologic measurement of superior displacement of the humeral head in the impingement syndrome

A method for directly measuring the position of the humeral head on the face of the glenoid in different positions of abduction of the arm was developed. We studied three subject groups: 12 patients with normal shoulders (group 1), 15 patients with stage II impingement syndrome (group 2), and 20 patients with rotator cuff tears or stage III impingement (group 3). The study consisted of a series of anteroposterior roentgenograms in the plane of the scapula with the arm in neutral rotation. Roentgenograms were obtained at 20 degrees intervals as the arm was elevated in the plane of the scapula from 0 degree to 120 degrees. Patients held a weight equal to 2 1/2% of body weight in the hand. The parameters measured were excursion of the humeral head on the glenoid face, expressed as the distance that the center of the head lies above or below the center of the glenoid, arm angle, scapulothoracic angle, and glenohumeral angle. For patients with normal shoulders (group 1), there was no significant change in position of the humeral head with arm elevation. In contrast, those with stage II impingement (group 2) had significant (p < 0.05) superior displacement of the center of the humeral head with arm elevation. Patients with rotator cuff tears (group 3) demonstrated a significant rise (p < 0.05) during the first 40 degrees of abduction. The average position of the humeral head in the two pathologic patient groups was superior (p < 0.05) to the average head position in the normal patient group. There was no significant difference in head position between patients with stage II impingement and patients with rotator cuff tear. The ratio of the glenohumeral angle to the scapulothoracic angle during abduction was calculated for our patient groups. In both patient groups, arm abduction had a larger scapulothoracic component than for normal shoulders. The superior migration of the humeral head is a probable result of cuff failure, either partial or complete.

Geometric and Mechanical Properties of the Coracoacromial Ligament and Their Relationship to Rotator Cuff Disease

One of the most common causes of pain and disability in the upper limb is inflammation of the rotator cuff tendons. When no significant bony abnormality exists in the surrounding structures, the coracoacromial ligament has been implicated as a possible cause of impingement on the cuff tendons. Geometric and mechanical properties of 20 coracoacromial ligaments, 10 from shoulders with rotator cuff tears and 10 from normal shoulders, were accurately determined. In comparing rotator cuff tear and normal specimens, statistically significant changes in geometric properties were measured in the lateral band, but not in the medial band, of the ligament. The lateral band, which is the region most likely to impinge on the rotator cuff, was shorter and had a larger cross-sectional area in specimens with rotator cuff tears. Although there were no statistical differences in structural properties of the ligament between normal and rotator cuff tear groups, significant changes were evident in material properties. Previously reported histologic differences in the ligament in shoulders with rotator cuff tears are supported by the decreased material properties measured in the current study. Whether the differences in the coracoacromial ligament cause impingement or are due to impingement is still unknown at this time.