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PubMed1994

The collagen types in the attachment zone of rotator cuff tendons in the elderly: an immunohistochemical study.

OBJECTIVE: The attachment zone of the rotator cuff tendons in the elderly was studied immunohistochemically in order to determine how degenerative changes affected the pattern of collagen fiber distribution. METHODS: Twenty-seven cuffs with their bony insertion were obtained from 22 postmortem cases of both sexes ranging in age from 52 to 90 years and without a history of shoulder ailments. In addition, 3 cuff specimens from cadavers in the 3rd and 4th decades were examined for comparison. Sections of formalin fixed tissues were stained by peroxidase antiperoxidase (PAP) technique using monoclonal antibodies against types I, II and III collagen. RESULTS: Degenerative changes affecting the fibrocartilage primarily were characterized by calcification, fibrovascular proliferation and microtears. In addition, they were found in all the cuff tendons of elderly individuals but not in those from younger subjects. Immunohistochemically, the attachment zone in areas without degenerative lesions showed collagen type I labelling strongly in bone but only moderately in the fibrocartilage. The predominant labelling in the fibrocartilage was for collagen type II, and collagen type III labelled principally in perichondrocytic areas. The tide-mark showed inconsistent labelling for any of the collagen types. In the presence of degenerative lesions, the disposition of fiber types was interrupted by calcification and microtears. Collagen type II composition of the fibrocartilage was markedly altered by the presence of fibrovascular tissue which labelled only for collagen type III. CONCLUSION: We conclude that severe degenerative changes in the cuff tendons of elderly individuals, alter the collagen characteristic of the rotator cuff and that the changes could be associated with impairment of biomechanical properties of the attachment zone, and may give rise to the clinical syndrome of enthesopathy.

Aged↗
PubMed1997

Massive, irreparable tears of the rotator cuff. Results of operative debridement and subacromial decompression.

Thirty-three consecutive patients in whom an irreparable tear of the rotator cuff had been treated with operative debridement and subacromial decompression were evaluated both preoperatively and postoperatively with regard to pain, ability to perform activities of daily living, range of motion, strength, and satisfaction. The assessments were performed with the Shoulder Score Index of the American Shoulder and Elbow Surgeons and the scoring systems of the University of California at Los Angeles and Constant and Murley. At the time of follow-up, twenty-six patients thought that the condition of the shoulder was improved; three, that it was unchanged; and four, that it was worse after the operation. There was a significant decrease in pain (p = 0.001) and significant increases in the range of motion (p = 0.038) and the ability to perform activities of daily living (p = 0.016). However, these improvements were inferior to those in reported series in which torn rotator cuffs had been repaired. Strength with elevation was decreased after the operations in the present series (p = 0.0007).

Activities of Daily Living↗
PubMed1992

Anatomy and relationships of the suprascapular nerve: anatomical constraints to mobilization of the supraspinatus and infraspinatus muscles in the management of massive rotator-cuff tears.

Thirty-one shoulders in eighteen cadavera were dissected to allow study of the neurovascular anatomy of the rotator cuff and to help determine the limits of mobilization of the cuff for the repair of chronic massive retracted tears. The dissection demonstrated the diameter, length, and relationships of the suprascapular nerve and its branches and made clear the dangers of extensive mobilization and advancement of the supraspinatus and infraspinatus muscles. The suprascapular nerve ran an oblique course across the supraspinatus fossa, was relatively fixed on the floor of the fossa, and was tethered underneath the transverse scapular ligament. In twenty-six (84 per cent) of the thirty-one shoulders, there were no more than two motor branches to the supraspinatus muscle, and the first was always the larger of the two. In twenty-six (84 per cent) of the thirty-one shoulders, the first motor branch originated underneath the transverse scapular ligament or just distal to it. In one shoulder (3 per cent), the first motor branch passed over the ligament. The average distance from the origin of the long tendon of the biceps to the motor branches of the supraspinatus was three centimeters. In fifteen (48 per cent) of the thirty-one shoulders, the infraspinatus muscle had three or four motor branches of the same size. The average distance from the posterior rim of the glenoid to the motor branches of the infraspinatus muscle was two centimeters. The motor branches to the supraspinatus muscle were fewer, usually smaller, and significantly shorter than those to the infraspinatus muscle. The standard anterosuperior approach allowed only one centimeter of lateral advancement of either tendon and limited the ability of the surgeon to dissect safely beyond the neurovascular pedicle. The advancement technique of Debeyre et al., or a modification of that technique, permitted lateral advancement of each muscle of as much as three centimeters and was limited by tension in the motor branches of the suprascapular nerve. In some situations, the safe limit of advancement may be even less. We concluded that lateral advancement of the rotator cuff is limited anatomically and may place the neurovascular structures at risk.

Female↗
PubMed1999

[Coraco-humeral space and rotator cuff tears].

PURPOSE OF THE STUDY: The anterior or subcoracoïd impingement is often mentioned but remains unprecise as far as clinical, radiological or even anatomical lesion are concerned. The purpose of our work was to study the different factors influencing the subcoracoïd space in case of cuff tear. METHODS: Our study was based on 206 shoulders operated for full-thickness rotator cuff tear. The SubCoracoïd Space (SPS), measured in millimeters on pre-operative arthro-CT-scan, was defined by the shortest distance between the coracoïd process and the humeral head. Muscular statement of the rotator cuff componants was graded according to Goutallier's and Bernageau's classification. According to literature data, we chose "6 mm" value as an inferior limit for normality. Shoulders were dispatched into three groups: group 1 was composed of supraspinatus +/- infraspinatus tears (59 cases), group 2 was composed of isolated lesions of the subscapularis (57 cases) and group 3 was composed of large cuff tears (supraspinatus +/- infraspinatus) involving also the subscapularis (90 cases). RESULTS: There was a statistically significant relationship between SCS narrowing, duration of symptoms and the non-traumatic onset. When there was no subscapularis lesion (group 1) the mean SCS was 9 +/- 2 mm, in 3 cases the SCS was inferior to 6 mm. In group 2 (isolated lesion of the subscapularis), the results were similar with 9 mm as an average and 3.5 p. 100 SCS inferior to 6 mm. On the contrary, in group 3 we found the major percentage of SCS inferior to 6 mm (27 p. 100) with an average of 7.7 +/- 3.5 mm. The long head of the biceps had no influence on the SCS. There was a strong statistically significant relationship between SCS size and fatty degeneration of the subscapularis muscle (p < 10-4) and infraspinatus muscle (p = 0.0004). Eventually, there was a statistically significant correlation between the subcoracoïd space and the sub acromial space. DISCUSSION: Measurements of the SCS in isolated lesions of the subscapularis show that the coracoïd process is not the mechanical factor responsible for tendon rupture. SCS narrowing is the consequence of a large cuff tear involving both the subscapularis and the infraspinatus tendon. Subscapularis tear is a necessary but not a sufficient condition by itself for SBS narrowing. Complete tear of the infraspinatus tendon and above all the muscular degeneration of the infraspinatus muscle is the other necessary condition for SCS narrowing. The horizontal control of the humeral head depends on subscapularis-infraspinatus muscular balance control. According to Patte's hypothesis SCS narrowing corresponds to an horizontal anterior translation of the humeral head due to fatty degeneration of subscapularis and infraspinatus muscle.

Adult↗
PubMed2006

The effect of double-row fixation on initial repair strength in rotator cuff repair: a biomechanical study.

PURPOSE: The purpose of this study was to compare the initial mechanical strength of 3 rotator cuff repair techniques. METHODS: A total of 30 fresh-frozen cadaveric shoulders were prepared, and full-thickness supraspinatus tears were created. Specimens were randomized and placed into 3 groups: (1) transosseous suture technique (group I: TOS, n = 10, 6F/4M), (2) single-row suture anchor fixation (group II: SRSA, n = 10, 6F/4M), and (3) double-row suture anchor fixation (group III: DRSA, n = 10, 6F/4M). Each specimen underwent cyclic load testing from 5 N to 180 N at a rate of 33 mm/sec. The test was stopped when complete failure (repair site gap of 10 mm) or a total of 5,000 cycles was attained. RESULTS: Group I (TOS) failed at an average of 75.3 +/- 22.49 cycles, and group II (SRSA) at an average of 798.3 +/- 73.28 cycles; group III (DRSA) had no failures because all samples were stopped when 5,000 cycles had been completed. Fixation strength of the DRSA technique proved to be significantly greater than that of SRSA (P < .001), and both suture anchor groups were significantly stronger than the TOS group (P < .001). CONCLUSIONS: Suture anchor repairs were significantly stronger than transosseous repairs. Furthermore, double-row suture anchor fixation was significantly stronger than was single-row repair. Therefore, double-row fixation may be superior to other techniques in that it provides a substantially stronger repair that could lead to improved biologic healing. CLINICAL RELEVANCE: A high incidence of incomplete healing occurs in rotator cuff repair. Use of double-row fixation may help the clinician to address some deficiencies in current methods by increasing the strength of the repair, potentially leading to improved healing rates.

Aged↗
PubMed1989

Rotator cuff tears: diagnostic performance of MR imaging.

To determine the diagnostic performance of magnetic resonance (MR) imaging in the evaluation of suspected rotator cuff tears, eight asymptomatic volunteers and 32 patients with rotator cuff tendonopathy who underwent surgery were examined with MR imaging. Twenty-four of these patients also underwent contrast arthrography. The ability of MR imaging to depict the size of cuff tears and the quality of torn tendon edges was also evaluated. The MR imaging and arthrographic studies were reviewed without knowledge of surgical results or of the other studies. A scoring system was developed and a score assigned to each patient's MR study. The sensitivity of MR imaging for all tears (partial and full thickness) was 0.91, and the specificity was 0.88; whereas the sensitivity and specificity of arthrography were each 0.71. The scoring system improved the sensitivity to 1.0 and the specificity to 0.92. Linear regression analysis showed excellent correlation between preoperative assessment of the size of rotator cuff tears and measurement at surgery (r = .95).

Humans↗
PubMed2005

A comparison of arthroscopic and open rotator cuff repair.

PURPOSE: The purpose of this study was to compare the results of all-arthroscopic repair of full-thickness rotator cuff tears including massive tear with those of open repair. TYPE OF STUDY: Nonrandomized control study. METHODS: We evaluated 100 consecutive patients (100 shoulders) who were treated for full-thickness rotator cuff tears either by all-arthroscopic (50 patients) or open repair (50 patients). The mean age was 57 years (range, 24 to 78 years). The mean follow-up period was 49 months (range, 25 to 83 months). Of all the patients, 7 had a small tear, 63 a medium tear, 17 a large tear, and 13 a massive tear; in the arthroscopic group, 5 had a small tear, 28 a medium tear, 9 a large tear, and 8 a massive tear. The results of the arthroscopic and open groups were compared using the shoulder rating scale of the University of California at Los Angeles (UCLA) and the Japanese Orthopaedic Association (JOA). RESULTS: The 2 groups were statistically similar in terms of age, gender, trauma incidence, tear size, duration of symptoms, and preoperative shoulder scores. The UCLA and JOA scores improved significantly in both groups postoperatively. Outcomes and the postoperative UCLA and JOA scores were not significantly different between the 2 groups. The postoperative UCLA and JOA scores in patients with a large-to-massive tear were significantly lower than those with a small-to-medium tear, but outcomes were not statistically different between the arthroscopic and open groups depending on the tear size. The percentage of satisfactory results of arthroscopic and open repair for small-to-medium tears was 97.0% and 94.6%, respectively. Those of arthroscopic and open repair for large-to-massive tears was 82.4% and 76.9%, respectively. CONCLUSIONS: Arthroscopic repair of small-to-massive tears had outcomes equivalent to those of open repair. Outcomes in patients with large-to-massive tears were inferior to those in patients with small-to-medium tears, regardless of repair method. LEVEL OF EVIDENCE: Level III, case-control study.

Activities of Daily Living↗
PubMed2000

Dynamic glenohumeral stability provided by the rotator cuff muscles in the mid-range and end-range of motion. A study in cadavera.

BACKGROUND: Both static and dynamic factors are responsible for glenohumeral joint stability. We hypothesized that dynamic factors could potentially operate throughout the entire range of glenohumeral motion, although capsuloligamentous restraints (a static factor) have been thought to be primarily responsible for stability in the end-range of motion. The purpose of this study was to quantitatively compare the dynamic glenohumeral joint stability in the end-range of motion (the position of anterior instability) with that in the mid-range by investigating the force components generated by the rotator cuff muscles. METHODS: Ten fresh-frozen shoulders from human cadavera were obtained, and all soft tissues except the rotator cuff were removed. The glenohumeral capsule was resected after the rotator cuff muscles had been released from the scapula. A specially designed frame positioned the humerus in 60 degrees of abduction and 45 degrees of extension with respect to the scapula. The compressive and shear components on the glenoid were measured before and after a constant force was applied individually to each muscle with the humerus in five different positions (from neutral to 90 degrees of external rotation). The dynamic stability index, a new biomechanical parameter reflecting these force components and the concavity-compression mechanism, was calculated. The higher the dynamic stability index, the greater the dynamic glenohumeral stability. RESULTS: In the mid-range of motion, the supraspinatus and subscapularis provided higher dynamic stability indices than did the other muscles (p < 0.05). On the other hand, when the position of anterior instability was simulated in the end-range of motion, the subscapularis, infraspinatus, and teres minor provided significantly higher dynamic stability indices than did the supraspinatus (p < 0.005). CONCLUSIONS: The rotator cuff provided substantial anterior dynamic stability to the glenohumeral joint in the end-range of motion as well as in the mid-range. CLINICAL RELEVANCE: A glenohumeral joint with a lax capsule and ligaments might be stabilized dynamically in the end-range of motion if the glenoid concavity is maintained and the function of the external and internal rotators, which are efficient stabilizers in this position, is enhanced.

Aged↗
PubMedDate not supplied

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.

Adult↗
PubMed1991

Normal rotator cuff: MR imaging with conventional and fat-suppression techniques.

The signal intensity and morphologic characteristics of the rotator cuff and surrounding structures at magnetic resonance (MR) imaging were investigated with five pulse sequences in 15 asymptomatic subjects. In all subjects, a focal region of relative increased signal intensity corresponding to the critical zone was observed in the supraspinatus tendon just proximal to its insertion. Soft-tissue signal intensity (isointense with muscle) was also located between the supraspinatus tendon and underlying joint capsule, interposed between the conjoined leaves of the supraspinatus and infraspinatus tendons, and superolateral to the conjoined cuff tendon, near its insertion. These regions were most conspicuous and most clearly defined with fat-suppression imaging. Small amounts of fluid were observed within the joint space and its recesses, the bicipital tendon sheath, and the subacromial-subdeltoid bursa. These and other MR imaging findings of this study previously have been regarded as indicative of rotator cuff abnormalities. These results will help refine the criteria for diagnosis of rotator cuff disorders with MR imaging.

Adult↗
PubMed1995

Rotator cuff calcifications: treatment with US-guided technique.

PURPOSE: The authors developed and tested a technique to treat calcific tendinitis in the rotator cuff with multiple needle punctures, aspiration, and lavage under ultrasonographic (US) guidance. MATERIALS AND METHODS: Atraumatic pain in the shoulders of a 46-year-old woman and a 42-year-old man was resistant to conservative therapy. With local anesthesia and continuous three-dimensional US visualization, the tips of two 18-gauge needles were placed within the calcification in the rotator cuff. Saline solution was injected and aspirated with the needles until the aspirate was free of calcific particles. RESULTS: Both patients experienced complete relief of pain and recovery of full range of motion, one on the 3rd day after treatment and one within 15 minutes. CONCLUSION: Use of this US-guided technique is successful to treat calcific tendinitis in the rotator cuff without the radiation exposure of fluoroscopic guidance.

Adult↗
PubMed1996

Glomus tumor of the musculotendinous junction of the rotator cuff. A case report.

A rare case of glomus tumor of the rotator cuff is presented. A 35-year-old man had a 20-year history of left shoulder pain. Through physical examination, muscular atrophy in the supraspinatus and infraspinatus muscles and restriction of shoulder motion was seen. Magnetic resonance imaging showed an abnormal oval shadow in the supraspinatus musculotendinous junction, and postcontrast computed tomographic scanning showed a small calcification focus in the tumor. Surgical excision of the tumor and rotator cuff reconstruction using Debeyre's procedure were done. Microscopic examination of the tumor showed a typical glomus tumor. It was difficult to diagnose glomus tumor in this patient before surgical intervention. Retrospective consideration indicated that the history of the present illness, computed tomographic scanning, and magnetic resonance imaging were critical for differential diagnosis.

Adult↗
PubMedDate not supplied

Glenoid osteophyte and rotator cuff tears: an anatomic study.

The purpose of this study was to determine the morphologic characteristics of the glenoid osteophyte and its relationship to rotator cuff tears. Eighty-six cadaveric shoulders were studied. After inspection of cuff pathology, the glenoid was examined with soft x-rays. Histologically, degenerative changes of the articular cartilage and the labrum were assessed. There were 30 shoulders with rotator cuff tears (35%). Two types of glenoid osteophyte were identified: angular and hooked. Both osteophytes were commonly observed in the anterior to inferior portions of the glenoid. The length of hooked osteophytes was significantly greater in shoulders with full-thickness tears (2.7 +/- 2.2 mm [mean plus minus SD]) than in those with other cuff conditions (P =.0058). The hooked osteophyte was more commonly observed in shoulders with full-thickness tears (43%) and associated with degenerative changes of the cartilage and labrum. We conclude that the hooked osteophyte of the glenoid is characteristic in shoulders with full-thickness tears of the rotator cuff.

Adult↗
PubMed2002

Extracorporeal shock-wave therapy for tendonitis of the rotator cuff. A double-blind, randomised, controlled trial.

We have performed a double-blind placebo-controlled trial of moderate doses of extracorporeal shock-wave therapy (ESWT) for non-calcific tendonitis of the rotator cuff. Adults (74) with chronic tendonitis of the rotator cuff were randomised to receive either active (1500 pulses ESWT at 0.12 mJ/mm2) or sham treatment, monthly for three months. All were assessed before each treatment, and at one and three months after the completion of treatment. The outcome was measured with regard to pain in the shoulder, including a visual analogue score for night pain, and a disability index. There were no significant differences between the two groups before treatment. The mean duration of symptoms in both groups was 23.3 months. Both showed significant and sustained improvements from two months onwards. There was no significant difference between them with respect to change in the Shoulder Pain and Disability Index (SPADI) scores or night pain over the six-month period. A mean (+/-SD; range) change in SPADI of 16.1 +/- 27.2 (0 to 82) in the treatment group and 24.3 +/- 24.8 (-11 to 83) in the sham group was noted at three months. At six months the mean changes were 28.4 +/- 25.9 (-24 to 69) and 30.4 +/- 31.2 (-12 to 88), respectively. Similar results were noted for night pain. We conclude that there is a significant and sustained placebo effect after moderate doses of ESWT in patients with non-calcific tendonitis of the rotator cuff, but there is no evidence of added benefit when compared with sham treatment.

Adult↗
PubMed2006

Biomechanical comparison of double-loaded suture anchors using arthroscopic Mason-Allen stitches versus traditional transosseous suture technique and modified Mason-Allen stitches for rotator cuff repair.

BACKGROUND: In recent studies objective evaluations have demonstrated that arthroscopic rotator cuff repairs can have higher failure rates than open repairs. Thus, there is a need for a stronger tissue-holding stitch for arthroscopical repair. The purpose of this study was to compare the biomechanical properties of traditional open transosseous suture technique and modified Mason-Allen stitches versus double-loaded suture anchors and arthroscopic Mason-Allen stitches in rotator cuff repair. METHODS: In 20 sheep shoulders the infraspinatus tendons were dissected from their insertion and were randomized to 2 repair groups: (1) repair with transosseous suture and modified Mason-Allen stitches, (2) repair with double loaded bioabsorbable suture anchors and arthroscopic Mason-Allen stitches: Both groups were coupled with braided, nonabsorbable polyester (Ethibond) suture sized USP No. 2. All repairs were cyclically loaded from 10 to 180N with the use of a materials testing machine. The number of cycles to gap formation of 5 and 10mm at the repair site and the mode of failure were recorded. RESULTS: The number of cycles to 5-mm gap was mean 634 (SD 106) for group 1 and mean 750 (SD 107) for group 2 (P<0.026). The corresponding values to 10-mm gap were mean 1573 (SD 161) for group 1, and mean 1789 (SD 183 cycles) for group 2 (P<0.012). In group 2 the mode of failure occurred by tissue pull-out, whereas in group 1 the failure occurred by a mixture of suture breakage and pull-out. CONCLUSIONS: This time-zero study demonstrates that the combination of bioabsorbable suture anchors and arthroscopic Mason-Allen stitches provides strength superior to that of the modified Mason-Allen transosseous suture technique under isometric cyclic loading conditions. However, additional evaluation is needed to examine the effects on the sustained strength of the repair throughout the healing process.

Absorbable Implants↗
PubMed1996

Transfer of latissimus dorsi for irreparable rotator-cuff tears.

We treated 12 shoulders in ten patients with irreparable rotator-cuff tears by transfer of the latissimus dorsi. There were nine men and one woman. Their average age was 64.0 years and the average follow-up was 35.6 months (26 to 42). The results were excellent in four shoulders, good in four, fair in one, and poor in three. Active forward flexion improved from a preoperative average of 99 degrees to a postoperative average of 135 degrees. Osteoarthritic changes appeared in five shoulders and proximal migration of the humeral head progressed in six. EMG revealed that nine of the 12 transferred muscles showed activity which was synergistic with the supraspinatus on external rotation with abduction. We conclude that latissimus dorsi transfer can be effective in restoring shoulder function after massive irreparable tears of the rotator cuff.

Activities of Daily Living↗
PubMed1995

The incidence of full thickness rotator cuff tears in a large cadaveric population.

The incidence of full thickness rotator cuff tears was determined after careful dissection and inspection of 235 male and female cadavers ranging in age from 27-102 years with an average age of 64.7 years. A total of 456 shoulders were examined. Partial thickness tears were excluded from the study. Seventy-eight shoulders, 17% (53 female, 26 male) were found to have full thickness tears. The average age of those cadavers with tears was 77.8 years as compared to 64.7 years in the intact group. The incidence of full thickness tears was also found to increase with increasing age. In cadavers under 60 years of age the incidence of rotator cuff tears was 6% as opposed to 30% in those over 60 years of age.

Adult↗
PubMed1997

Cyclic loading of anchor-based rotator cuff repairs: confirmation of the tension overload phenomenon and comparison of suture anchor fixation with transosseous fixation.

Previous experimental studies of failure of rotator cuff repair have involved single pull to ultimate load. Such an experimental design does not represent the cyclic loading conditions experienced in vivo. We created 1 x 2 cm rotator cuff defects in 16 cadaver shoulders, repaired each defect with three Mitek-RC suture anchors (Mitek Surgical Products, Inc, Westwood, MA) using simple sutures of No. 2 Ethibond, and cyclically loaded the repairs by a servohydraulic materials test system actuator at physiological rates and loads (rate of 33 mm/s, load 180 N). A progressive gap was noted in each specimen, for a 100% rate of failure of the repairs. The central suture always failed first and by the largest magnitude, confirming tension overload centrally. One specimen exhibited combined bone and tendon failure, but the other 15 specimens failed through the tendon. Overall, the repairs failed to 5 mm and 10 mm at an average of 61 cycles and 285 cycles, respectively. Half the specimens were less than 45 years of age and had a 5-mm and 10-mm failure at an average of 107 and 478 cycles, respectively. The other half were over 45 years of age and failed to 5 mm and 10 mm at an average of 17 and 91 cycles, respectively, indicating more rapid failure of the rotator cuff tendons in the older group, and this was statistically significant (P < or = .02). Comparison of suture anchor fixation in this study with transosseous bone tunnel fixation in a previous cyclic loading study at this institution indicates that bone fixation by suture anchors is significantly less prone to failure than bone fixation through bone tunnels (P = .0008). Changing the bone fixation from bone tunnels to suture anchors effectively transferred the weak link from bone to tendon.

Adolescent↗