Inhibition of apoptosis exacerbates fatigue-damage tendon injuries in an in vivo rat model.

Tendinopathy is a common and progressive musculoskeletal disease. Increased apoptosis is an end-stage tendinopathy manifestation, but its contribution to the pathology of the disease is unknown. A previously established in vivo model of fatigue damage accumulation shows that increased apoptosis is correlated with the severity of induced tendon damage, even in early onset of the disease, supporting its implication in the pathogenesis of the disease. Consequently, this study aimed to determine: (1) whether apoptosis could be inhibited after fatigue damage and (2) whether its inhibition could lead to remodeling of the extracellular matrix (ECM) and pericellular matrix (PCM), to ultimately improve the mechanical properties of fatigue-damaged tendons. The working hypothesis was that, despite the low vascular nature of the tendon, apoptosis would be inhibited, prompting increased production of matrix proteins and restoring tendon mechanical properties. Rats received 2 or 5 d of systemic pan-caspase inhibitor (Q-VD-OPh) or dimethyl sulfoxide (DMSO) carrier control injections starting immediately prior to fatigue loading and were sacrificed at days 7 and 14 post-fatigue-loading. Systemic pan-caspase inhibition for 2 d led to a surprising increase in apoptosis, but inhibition for 5 d increased the population of live cells that could repair the fatigue damage. Further analysis of the 5 d group showed that effective inhibition led to an increased population of cells producing ECM and PCM proteins, although typically in conjunction with oxidative stress markers. Ultimately, inhibition of apoptosis led to further deterioration in mechanical properties of fatigue-damaged tendons.

Delayed exercise promotes remodeling in sub-rupture fatigue damaged tendons.

Tendinopathy is a common musculoskeletal injury whose treatment is limited by ineffective therapeutic interventions. Previously we have shown that tendons ineffectively repair early sub-rupture fatigue damage. In contrast, physiological exercise has been shown to promote remodeling of healthy tendons but its utility as a therapeutic to promote repair of fatigue damaged tendons remains unknown. Therefore, the objective of this study was to assess the utility of exercise initiated 1 and 14 days after onset of fatigue damage to promote structural repair in fatigue damaged tendons. We hypothesized that exercise initiated 14 days after fatigue loading would promote remodeling as indicated by a decrease in area of collagen matrix damage, increased procollagen I and decorin, while decreasing proteins indicative of tendinopathy. Rats engaged in 6-week exercise for 30 min/day or 60 min/day starting 1 or 14 days after fatigue loading. Initiating exercise 1-day after onset of fatigue injury led to exacerbation of matrix damage, particularly at the tendon insertion. Initiating exercise 14 days after onset of fatigue injury led to remodeling of damaged regions in the midsubstance and collagen synthesis at the insertion. Physiological exercise applied after the initial biological response to injury has dampened can potentially promote remodeling of damaged tendons.

Tendon fatigue in response to mechanical loading.

Tendinopathies are commonly attributable to accumulation of sub-rupture fatigue damage from repetitive use. Data is limited to late stage disease from patients undergoing surgery, motivating development of animal models, such as ones utilizing treadmill running or repetitive reaching, to investigate the progression of tendinopathies. We developed an in vivo model using the rat patellar tendon that allows control of the loading directly applied to the tendon. This manuscript discusses the response of tendons to fatigue loading and applications of our model. Briefly, the fatigue life of the tendon was used to define low, moderate and high levels of fatigue loading. Morphological assessment showed a progression from mild kinks to fiber disruption, for low to high level fatigue loading. Collagen expression, 1 and 3 days post loading, showed more modest changes for low and moderate than high level fatigue loading. Protein and mRNA expression of Ineterleukin-1ß and MMP-13 were upregulated for moderate but not low level fatigue loading. Moderate level (7200 cycles) and 100 cycles of fatigue loading resulted in a catabolic and anabolic molecular profile respectively, at both 1 and 7 days post loading. Results suggest unique mechanisms for different levels of fatigue loading that are distinct from laceration.

Latissimus dorsi tendon transfer for massive rotator cuff tears: a cadaveric study.

Certain massive defects of the rotator cuff tendinous insertion cannot be repaired primarily to the greater tuberosity. If restoration of strength is an important treatment goal to the patient, then a tendon transfer may be considered. Ten cadaver shoulders were dissected to define the anatomy of the latissimus dorsi tendon (LDT) and its distance relationship to the axillary and radial nerves with the arm in various positions. The axillary nerve lies superior to the LDT insertion, and the radial nerve passes medial and inferior to the LDT insertion. With the arm internally rotated and the shoulder flexed, the distances from the axillary and radial nerves to the LDT insertion were 2.3 cm and 2.8 cm, respectively. With the arm internally rotated and the shoulder abducted, the distances from the axillary and radial nerves to the LDT insertion were 1.8 cm and 2.0 cm, respectively. Understanding specific anatomic relationships is one of the factors contributing to the safety of the LDT transfer procedure with respect to nerve injury.

Revision rotator cuff repair: factors influencing results.

BACKGROUND: Revision rotator cuff repair is a surgical challenge, and the results have generally been inferior to those of primary repair. We examined the results of revision rotator cuff repair in a large series of patients and assessed which subgroups of patients had the greatest chance for a satisfactory functional outcome. METHODS: A revision rotator cuff repair was performed in eighty patients after the failure of a previous operative repair. The average age of the patients at the time of the revision was fifty-nine years. Prior to revision, the average pain score was 7.4 points (with 0 points indicating no pain and 10 points, severe pain) and the active range of motion of the shoulder averaged 105 degrees of elevation, 39 degrees of external rotation, and internal rotation to the eleventh thoracic vertebra. All patients underwent repeat repair of the rotator cuff tendons to bone. Additional procedures included revision acromioplasty (fifty-three patients; 66%) and distal clavicular excision (twenty-six patients; 33%), among others. RESULTS: After an average duration of follow-up of forty-nine months, the result was rated as satisfactory (excellent, good, or fair) in fifty-five patients (69%) and as unsatisfactory (poor) in twenty-five (31%). At the time of the latest follow-up, the average pain score had improved to 3.0 points and the active range of motion averaged 130 degrees of elevation, 53 degrees of external rotation, and internal rotation to the tenth thoracic vertebra. Improved results were associated with an intact deltoid origin, good-quality rotator cuff tissue, preoperative active elevation of the arm above the horizontal, and only one prior procedure. All seventeen patients who met all four of these criteria had a satisfactory result. CONCLUSIONS: The results of revision rotator cuff repair are inferior to those of primary repair. While pain relief can be reliably achieved in most patients, the functional results are improved principally in patients with an intact deltoid origin, good-quality rotator cuff tissue, preoperative elevation above the horizontal, and only one prior procedure.

Glenohumeral mechanics: a study of articular geometry, contact, and kinematics.

Stereophotogrammetry was used to investigate the functional relations between the articular surface geometry, contact patterns, and kinematics of the glenohumeral joint. Nine normal shoulder specimens were elevated in the scapular plane by using simulated muscle forces in neutral rotation (NR) and starting rotation (SR). Motion was quantified by analyzing the translations of the geometric centers of the humeral head cartilage and bone surfaces relative to the glenoid surface. In both NR and SR, the ranges of translations of the center of the humeral head cartilage surface were greatest in the inferior-superior direction (NR 2.0 +/- 0.7 mm, SR 2.9 +/- 1.2 mm). Results of this study also show that joints with less congruence of the articular surfaces exhibit larger translations, and elevation in SR yields greater translations than in NR. Kinematic analyses with the humeral head bone surface data yielded larger values of translation than analyses that used the cartilage surface data, suggesting that similar overestimations may occur in radiographic motion studies. Results of this study demonstrate that small translations of the humeral head center occurred in both SR and NR. The proximity of the origin of the helical axes to the geometric center of the humeral head articular surface confirmed that glenohumeral elevation is mainly rotation about this geometric center with small translations.

The pathophysiology of shoulder instability.

Over the last several decades there has been an improved understanding of the intricate anatomy that provides stability to the glenohumeral joint. In addition, significant advances in identifying the pathologic etiology of the unstable shoulder have occurred because of basic science glenohumeral ligament cutting studies, clinical evaluation, and the advent of arthroscopic evaluation and treatment of the unstable shoulder. This article will review the pertinent anatomy of the normal glenohumeral joint and will carefully review the pathoanatomy found in the unstable shoulder. Sports medicine specialists who treat athletes with unstable shoulders should have a firm understanding of both the normal and pathologic shoulder conditions to be able to provide the best care for these athletes.

Effects of repetitive subfailure strains on the mechanical behavior of the inferior glenohumeral ligament.

The mechanical response of the inferior glenohumeral ligament to varying subfailure cyclic strains was studied in 33 fresh frozen human cadaver shoulders. The specimens were tested as bone-ligament-bone preparations representing the 3 regions of the inferior glenohumeral ligament (superior band and anterior and posterior axillary pouches) through use of uniaxial tensile cycles. After mechanical preconditioning, each specimen was subjected to 7 test segments, consisting of a baseline strain level L1 (400 cycles) alternating with either 1 (group A, 10 shoulders), 10 (group B, 13 shoulders), or 100 (group C, 10 shoulders) cycles at increasing levels (L2, L3, L4) of subfailure strain. Cycling to higher levels of subfailure strain (L2, L3, L4) produced dramatic declines in the peak load response of the inferior glenohumeral ligament for all specimens. The group of ligaments subjected to 100 cycles of higher subfailure strains demonstrated a significantly greater decrease in load response than the other 2 groups. Ligament elongation occurred with cyclic testing at subfailure strains for all 3 groups, averaging 4.6% +/- 2.0% for group A, 6.5% +/- 2.6% for group B, and 7.1% +/- 3.2% for group C. Recovery of length after an additional time of nearly 1 hour was minimal. The results from this study demonstrate that repetitive loading of the inferior glenohumeral ligament induces laxity in the ligament, as manifested in the peak load response and measured elongations. The mechanical response of the ligament is affected by both the magnitude of the cyclic strain and the frequency of loading at the higher strain levels. The residual length increase was observed in all of the specimens and appeared to be largely unrecoverable. This length increase may result from accumulated microdamage within the ligament substance, caused by the repetitively applied subfailure strains. The clinical relevance of the study is that this mechanism may contribute to the development of acquired glenohumeral instability, which is commonly seen in the shoulders of young athletes who participate in repetitive overhead sports activities.

Anterior and posterior musculotendinous anatomy of the supraspinatus.

The objective of this study was to quantitatively describe the supraspinatus musculotendinous architecture. After supraspinatus muscles were harvested from 25 embalmed shoulders, each muscle was divided into an anterior and posterior muscle belly on the basis of muscle fiber insertion. Pennation angles and musculotendinous dimensions were measured, and the physiologic cross-sectional area was calculated for each muscle belly. The physiologic cross-sectional areas of the anterior and posterior bellies were calculated to be 140 +/- 43 mm2 and 62 +/- 25 mm2, respectively, whereas their tendon cross-sectional areas were 26.4 +/- 11.3 mm2 and 31.2 +/- 10.1 mm2, respectively. The average anterior-to-posterior ratios for the muscle physiologic cross-sectional area and the tendon cross-sectional area were 2.45 +/- 0.82 and 0.87 +/- 0.30, respectively. Thus, a larger anterior muscle pulls through a smaller tendon area. These data suggest that physiologically, anterior tendon stress is significantly greater than posterior tendon stress and that rotator cuff tendon repairs should incorporate the anterior tendon whenever possible, inasmuch as it functions as the primary contractile unit.

Three-dimensional analysis of the proximal part of the humerus: relevance to arthroplasty.

BACKGROUND: Recreation of normal anatomical relationships may be important to optimize the outcome of proximal humeral arthroplasty. With use of computerized tomographic data and three-dimensional computer modeling, we concurrently studied both extramedullary and intramedullary humeral morphology, including canal shape, and related these findings to the design of proximal humeral prostheses. METHODS: Sixty cadaveric humeri (thirty pairs: fifteen from male donors and fifteen from female donors) were studied. Three-dimensional computer models were built from canal and periosteal contours extracted from computerized tomographic data and multiple measured anatomical parameters, including humeral canal axis, humeral head center, and hinge point offset; greater tuberosity and bicipital groove offset; humeral head center, radius, thickness, retroversion, and inclination; and size and torsion of sections of the canal. RESULTS: On the average, the humeral head center was offset both medially (seven millimeters) and posteriorly (two millimeters) from the humeral axis. The humeral head hinge point did not line up with the axis but instead was laterally offset by an average of seven millimeters. The average humeral head thickness was nineteen millimeters. The humeral head thickness and length were proportionately linked. There was marked variability in all of these parameters. Humeral head inclination averaged 41 degrees but was less variable than previously described, with 95 percent of our sample within the range of 35 to 46 degrees. The proximal section of the humeral canal was retroverted, and the retroversion was found to be similar to that of the humeral head on statistical analysis. Version of the middle and distal sections of the canal, however, was dissimilar to that of the proximal section of the canal. Proximal humeral retroversion was found to be extremely variable and averaged 19 degrees. The accuracy, reliability, and repeatability of the computer-based-model measurements were found to be excellent. CONCLUSIONS: Measurements of external proximal humeral morphology made with three-dimensional computer models of cadaveric specimens derived from the Midwestern United States agreed, in general, with those described for different populations evaluated with different measuring techniques. Proximal humeral morphology was extremely variable as highlighted by the large ranges of measurements seen for all variables. Examination of the intramedullary morphology showed that there is an internal version, with measurements dependent on the canal distance distal to the anatomical neck. CLINICAL RELEVANCE: Because of the marked variabilities seen in proximal humeral morphology, newer prosthetic designs are now allowing surgeons to control multiple prosthetic variables. An understanding of the normal values for proximal humeral morphology can serve as an important guideline for component selection, especially when the normal anatomy is distorted. Additionally, variations in intramedullary version may have important consequences for future designs of press-fit proximal humeral replacement.

Osteolysis of the distal clavicle: long-term results of arthroscopic resection.

PURPOSE: The purpose of this study was to evaluate the outcome of arthroscopic distal clavicle resection by the direct superior approach for treatment of isolated osteolysis of the distal clavicle. TYPE OF STUDY: Case series. MATERIALS AND METHODS: Forty-one shoulders in 37 patients underwent arthroscopic resection of the distal clavicle. Thirty-three patients were male and 4 female, with an average age of 39 years. All patients complained of pain localized to the acromioclavicular joint region. Symptoms began after a traumatic event in 18 shoulders and were associated with repetitive stressful activity in 23 shoulders. RESULTS: At an average follow-up of 6.2 years, 22 shoulders had excellent results, 16 had good results, and 3 were failures. All 3 failures occurred in patients with a traumatic etiology. CONCLUSIONS: Arthroscopic resection for osteolysis of the distal clavicle has results comparable to open excision with low morbidity. Patients with a traumatic etiology had slightly worse results compared with patients with a microtraumatic etiology.

Indwelling interscalene catheter anesthesia in the surgical management of stiff shoulder: a report of 100 consecutive cases.

One hundred consecutive stiff shoulders in 93 patients resistant to conservative therapy were treated with surgery and intermittent regional anesthesia via indwelling interscalene catheter. Each patient underwent manipulation and one of several operative treatments to release any additional contracture. The indwelling interscalene catheter remained in place and functioned well for an average of 3 days in 87 shoulders. At an average follow-up of 3.0 years, overall clinical results according to Neer's criteria were excellent in 39 shoulders (39%), satisfactory in 28 (28%), and unsatisfactory in 33 (33%). Patients reported no or mild pain in 83 (83%) of the shoulders in the study. At final follow-up, average gains in motion were 44 degrees of elevation (115 degrees to 159 degrees), 31 degrees of external rotation (22 degrees to 53 degrees), and 5 spine segments of internal rotation (L4 to T11). At final follow-up, 95% of the elevation and 79% of the external rotation achieved intraoperatively were maintained. The best results were obtained in those shoulders with idiopathic stiffness (88% excellent or satisfactory results); the worst results were in the postsurgical shoulders (47% excellent or satisfactory results). There were no catheter-related complications. The use of an indwelling interscalene catheter for postoperative pain control is a safe technique that facilitates early physical therapy in a patient population with a high risk of developing recurrent stiffness.

Operative results of the inferior capsular shift procedure for multidirectional instability of the shoulder.

BACKGROUND: Neer and Foster previously described the inferior capsular shift procedure for treating multidirectional instability of the shoulder and reported preliminary results that were quite satisfactory. The purpose of our study was to perform a longer-term follow-up evaluation of the efficacy of the inferior capsular shift procedure for treating multidirectional instability of the shoulder. METHODS: An inferior capsular shift procedure was used to treat multidirectional instability of the shoulder in forty-nine patients (fifty-two shoulders). All patients had failed to respond to an exercise program. In this series, the operative approach (anterior or posterior) was based on the major direction of the instability, as determined by the preoperative history and physical examination and as verified by examination with the patient under anesthesia. In all of the patients, the inferior capsular shift was the primary attempt at operative stabilization. The repair consisted of a lateral-side (or humeral-side) shift of the capsule to reduce capsular redundancy and, when necessary, a reattachment of the avulsed labrum to the anteroinferior aspect of the glenoid. RESULTS: A redundant capsular pouch was seen in all of the shoulders in this series. In addition, detachment of the anteroinferior aspect of the labrum was found in ten shoulders and an anterior fracture of the glenoid rim was seen in two shoulders. At an average of sixty-one months (range, twenty-four to 132 months), results were available for forty-nine shoulders (forty-six patients). Thirty shoulders (61 percent) had an excellent overall result, sixteen (33 percent) had a good result, one (2 percent) had a fair result, and two (4 percent) had a poor result. Forty-seven (96 percent) of the forty-nine shoulders remained stable at the time of follow-up. Two of the thirty-four shoulders that had been repaired through an anterior approach began to subluxate anteroinferiorly again. None of the fifteen shoulders that had been repaired through a posterior approach had recurrent instability. Full function, including the ability to perform strenuous manual tasks, was restored to forty-five shoulders (92 percent). A return to sports was possible after thirty-one (86 percent) of the thirty-six procedures done in athletes; however, a return to the premorbid level of participation was possible after only twenty-five (69 percent) of the thirty-six procedures. CONCLUSIONS: The results in this series demonstrate the efficacy and the durability of the results of the inferior capsular shift procedure for the treatment of shoulders with multidirectional instability. The procedure directly addresses the major pathological feature - a redundant joint capsule. Similar results were seen with either an anterior or a posterior approach, and we continue to approach shoulders with multidirectional instability on the side of greatest instability. A postoperative brace was reserved for patients in whom a posterior approach had been used or in whom an anterior approach had involved extensive posterior capsular dissection (ten of the thirty-four shoulders treated with the anterior approach).

Arthroscopic debridement of the shoulder for osteoarthritis.

Twenty-five patients underwent arthroscopic debridement to treat early glenohumeral osteoarthritis. The group consisted of 19 men and 6 women with an average age of 46 years (range, 27 to 72 years.) The operative procedure consisted of lavage of the glenohumeral joint, debridement of labral tears and chondral lesions, loose body removal, and partial synovectomy and subacromial bursectomy. Follow-up averaged 34 months, with a range of 12 to 63 months. Overall, results were rated as excellent in 2 patients (8%), good in 19 patients (72%), and unsatisfactory in 5 (20%). Two patients had complete relief of pain, 18 patients had only occasional mild pain, and 5 had moderate to severe pain postoperatively. Of the 12 patients with marked preoperative stiffness, 10 (83%) had improvement in range of motion postoperatively. Arthroscopic debridement is a reasonable approach for treating early glenohumeral osteoarthritis that has failed to respond to nonoperative treatment, in which the humeral head and glenoid remain concentric, and where there is still a visible joint space on an axillary radiograph. The procedure is not recommended when there is severe joint incongruity or large osteophytes.

Comparison of arthroscopic and open revision decompression for failed anterior acromioplasty.

Thirty-six consecutive patients who underwent revision decompression for refractory subacromial impingement were studied retrospectively. Average interval from the primary decompression procedure to revision was 29 months. Eighteen patients underwent arthroscopic and 18 underwent open revision. Six (33%) patients in the arthroscopic group and 12 (67%) patients in the open group were workers' compensation cases. At an average follow-up of 26 months, 17 (94%) patients in the arthroscopic group and 8 (44%) in the open group were satisfied with their procedure. Comparing workers' compensation patients, 5 of 6 in the arthroscopic group and 4 of 12 in the open group were satisfied. For nonworkers' compensation patients, all 12 patients in the arthroscopic group and 4 of 6 in the open group were satisfied. Average pain scores and postoperative range of motion was improved in both groups. Dense subacromial scarring with thick, fibrous adhesions was present in all patients. Residual, prominent bone, or an acromial spur was found in 20 (56%) patients. Overall, revision arthroscopic subacromial decompression was superior to open revision. However, there were more workers' compensation patients in the open group. Workers' compensation patients fared worse for both groups, but a significant proportion (83%) of the arthroscopic group was satisfied. Since subacromial scarring may be the most important pathology, arthroscopy is less invasive, allowing earlier, unrestricted postoperative rehabilitation and proving more effective.

Portal-extension approach for the repair of small and medium rotator cuff tears.

One hundred ten consecutive cases (110 patients) of arthroscopically assisted rotator cuff repair through a limited, portal-extension approach were retrospectively reviewed. The average age of our patients was 58 years (range, 30 to 79). There were 35 women and 75 men. The dominant shoulder was affected in 67 patients (61%). All patients underwent a standard arthroscopic decompression. Acromioclavicular resections were performed in 15% of patients. The anterolateral portal was extended in the direction of Langer's lines to a total length of no more than 3 cm. The torn tendon was accessed through a small deltoid muscle split and repaired with nonabsorbable sutures. At an average follow-up of 35 months (range, 24 to 86), 106 patients (96%) had achieved excellent or satisfactory results. The average American Shoulder and Elbow Surgeons pain score improved from 7 preoperatively to 2 postoperatively. All but four patients were satisfied with the clinical result and reported significant improvement in active elevation and strength and a significant lessening of pain. Late acromioclavicular joint pain contributed to failure in three of the four patients with unsatisfactory results in this series. The results of this study suggest that, in selected patients with small to medium rotator cuff tears, arthroscopically assisted repair through an anterolateral portal-extension approach can produce excellent results.

Open revision stabilization surgery for recurrent anterior glenohumeral instability.

Fifty patients (average age, 27 years) who underwent revision anterior stabilization surgery for failed anterior glenohumeral instability procedures were retrospectively reviewed. Failure of the original procedure occurred subsequent to significant trauma in only 17 of 50 shoulders. At revision, 49 shoulders underwent an anteroinferior capsular shift procedure and 23 underwent concurrent repair of a Bankart lesion. One shoulder was treated with a coracoid transfer to reconstruct the anteroinferior glenoid. At an average follow-up of 4.7 years (range, 2 to 10), there were 36 excellent and 3 good results (78%). Eleven shoulders were considered unsatisfactory (22%); 7 of these 11 patients had a diagnosis of voluntary dislocation. All 17 patients who had failed results after significant trauma had excellent results after revision surgery. However, only 22 of the 33 patients (67%) with atraumatic recurrent instability achieved excellent or good results after revision surgery. This difference was statistically significant. No patients had radiographic evidence of osteoarthritis at the most recent follow-up. Range of motion, return to function, and glenohumeral stability can be reliably restored in a high percentage of patients after revision anterior stabilization surgery for glenohumeral instability. However, the results are not as predictable as for primary surgery. Factors associated with poor results of revision repair included an atraumatic cause of failure, voluntary dislocations, and multiple prior stabilization attempts.

Shoulder dislocations in the young patient.

Shoulder dislocations are often seen in young patients, particularly those patients involved in collision sports. A conservative approach to treating these injuries includes protection from early re-injury, rehabilitation, and gradual return to athletics and use. It is important to recognize associated injuries such as fractures and nerve injuries. Surgical management is considered early for the small subgroup with the highest risk of recurrence: young athletes suffering a first traumatic dislocation returning to competitive athletics. Late operative repair is reserved for those who fail extensive nonoperative management.

Posttraumatic arthritis.

The surgical management of posttraumatic arthritis is one of the most difficult problems encountered in shoulder surgery. Bone and soft tissue abnormalities resulting from the initial injury and from any subsequent surgery must be addressed to achieve the best outcome possible. A review of the literature reveals distinctly inferior results and a higher rate of complications following surgical treatment of posttraumatic sequelae compared with the surgical treatment of acute proximal humeral fractures. The authors present helpful hints for dealing with the complex problems encountered in the posttraumatic setting.