Search

Pathologic processes intrinsic and extrinsic to the tendons have been proposed as the underlying cause of rotator cuff disease, but the precise etiology is not known. Tear formation is, in part, attributable to the accumulation of subrupture tendon fatigue damage. We review the molecular, mechanical, and structural changes induced in tendons subjected to controlled amounts of fatigue loading in an animal model of early tendinopathy. The distinct tendon responses to low and moderate levels of loading, as opposed to high levels, provide insight into the potential mechanisms for the therapeutic benefits of exercise in the treatment of rotator cuff tendinopathy. The progression of damage accumulation leading to fiber rupture and eventual tendon tearing seen with higher loading illustrates the progression from tendinopathy to full-thickness tearing. We hope that this more realistic animal model of tendon fatigue damage will allow better assessment of biologic, mechanical, tissue-engineering, and rehabilitation strategies to improve repair success., (Copyright © 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)

Elevation of the deltoid insertion (DI) has been recommended, but little is known about its anatomy or importance for deltoid function. The purpose of this study is to determine the dimensions of the DI with specific reference to the deltopectoral approach. The deltoid was exposed and detached at its origin in 36 cadaveric shoulders. The morphology of the DI was documented, and its relationship with the pectoralis major insertion and the axillary and radial nerves was recorded. The anterior, middle, and posterior deltoid muscle fibers entered into the DI in a V-shaped tendinous confluence with a broad posterior band and a narrow separate anterior band, which accounted for the anterior one fifth of the DI (0.44 cm). The deltoid insertion was separated from the pectoralis major insertion by as little as 2 mm in 31 of 36 specimens. The distance between the axillary nerve and the DI averaged 5.6 cm anteriorly and 4.5 cm posteriorly. The distance between the radial nerve and posterior deltoid insertion averaged 2.4 cm proximally and 1.6 cm distally. Exposure during the deltopectoral approach is most limited by the close proximity of the deltoid and pectoralis major insertions. Our study would suggest that partial anterior DI release (greater than one fifth) could compromise the anterior deltoid. The axillary and radial nerves are not at significant risk when operating in the region of the anterior DI.

Specialized magnetic resonance imaging (MRI) was performed in 42 painful shoulder arthroplasties, 22 of which underwent subsequent revision surgery, allowing surgical confirmation of the pathology identified on MRI. One hemiarthroplasty was excluded because of motion artifact, leaving 21 studies (19 patients) to be correlated retrospectively to the surgical findings. At the time of revision surgery, there were full-thickness rotator cuff tears in 11 of 21 shoulders; MRI correctly predicted these in 10 of 11 shoulders. Full-thickness subscapularis tears were the most common finding (8/11 shoulders). Of the 21 shoulders, 10 did not have a rotator cuff tear, and MRI correctly predicted the absence of a tear in 8 of 10. MRI also correctly predicted glenoid cartilage wear in 8 of 9 shoulders. With limited pulse-sequence parameter modification, the data from this preliminary study suggest that MRI may be a useful technique with which to determine the integrity of the rotator cuff and residual cartilage and, thus, is potentially a tool in the management of painful shoulder arthroplasty.

Subcoracoid transfer of the pectoralis major has recently been described as a reconstruction for subscapularis insufficiency. The purpose of this study was to examine the surgically relevant anatomy of this transfer. The importance of understanding this anatomy was recently highlighted to us following our encounter with musculocutaneous neuropraxia in 2 patients after transfer of the entire pectoralis major, one deep to the musculocutaneous nerve. Dissections were performed on 20 fresh, whole human cadavers in which the entire pectoralis major muscle, medial and lateral pectoral nerves, and musculocutaneous nerve were explored and quantified. The relationship between the pectoralis major and the conjoined tendon was studied in situ and after simulated transfers. The medial and lateral pectoral nerves were located far medial to the pectoralis major tendon insertion and appeared to be safe from injury as long as surgical dissection remained lateral to the pectoris minor and less than 8.5 cm from the humeral insertion. Transfer of the pectoralis major superficial to the musculocutaneous nerve created less tension than transfer deep to the musculocutaneous nerve. Because proximal innervation of the coracobrachialis and short head of the biceps is not an uncommon occurrence, a split pectoralis major transfer, release of the proximal musculocutaneous branches, or debulking of the pectoralis major muscle belly may be required in some instances to prevent tension on the nerve. Because of the variability and location of the musculocutaneous nerve, it should always be visualized operatively. Transfer of the pectoralis major tendon lateral to the biceps tendon appeared to best restore the muscle length-tension relationship.

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 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.

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.

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.

Eleven fresh-frozen cadaver shoulders were dissected to define the anatomy of the teres major muscle and tendon and to determine the muscle's potential for use as a tendon transfer to the humeral head. Of the 11 specimens, 7 had Mathes type II circulation. The primary and secondary pedicles, from the circumflex scapular artery, entered the muscle 4.1 cm and 0.5 cm from the scapula, respectively. The lower subscapular nerve entered 4.1 cm from the scapula. Mean tendon and muscle lengths were 2.0 and 11.8 cm, respectively. As a unipolar transfer, the tendon reached the greater tuberosity in all but 1 specimen. The bipolar transfer offered numerous theoretical possibilities. We believe that the teres major has an appropriate vascular supply and adequate length to make it suitable for tendon transfer to the humeral head.

When the diagnosis of suprascapular nerve entrapment syndrome is being considered, variations in anatomy are possible etiologic factors. Seventy-nine shoulders from 41 cadavers were examined for anatomic variations and for ganglion cyst formation in the suprascapular notch, superior transverse scapular ligament, and inferior transverse scapular ligament. The morphologic evaluation of the suprascapular notch revealed a "U" shape in 77% and a "V" shape in 23%, with 89% of cadavers having the same notch shape bilaterally. In 23% of shoulders a variation of the superior transverse scapular ligament was demonstrated such as partial and complete ossification and multiple bands including the first report of a trifid superior transverse scapular ligament. An inferior transverse scapular ligament was observed in only 14% of shoulders. One ganglion cyst was identified, for an incidence of 1%. The mass was located in the supraspinatus fossa adjacent to the superior transverse scapular ligament and appeared to compress and alter the course of the suprascapular nerve. When operative treatment is elected for suprascapular nerve entrapment syndrome and an open surgical approach is undertaken, the location and source of disease and morphologic and anatomic variants must be recognized to ensure adequate access and complete decompression of the suprascapular nerve. The classical description of the superior transverse scapular ligament as a completely nonossified single band should be expected, on average, in approximately three fourths of the cases. Partial or complete ossification and anomalous bands of the superior transverse scapular ligament or a ganglion cyst along the course of the suprascapular nerve may be encountered. Although a superior transverse scapular ligament should be anticipated in all shoulders, an inferior transverse scapular ligament will be a much less frequent finding. The role and significance of suprascapular notch morphologic characteristics warrant further investigation.

Thirty patients (31 shoulders) were retrospectively reviewed after hemiarthroplasty for glenohumeral osteoarthritis. Ten shoulders had primary osteoarthritis, and 21 shoulders had secondary osteoarthritis. Glenoid surface wear was evaluated and classified as either type I, concentric, (15 shoulders) or type II, nonconcentric, (16 shoulders). Postoperative results were reviewed with the American Shoulder and Elbow Surgeons' evaluation form, Neer classification, and the Constant score. Overall, 23 (74%) shoulders achieved satisfactory results, and 8 (26%) shoulders had unsatisfactory results. Results were similar in the primary and secondary osteoarthritis groups. Outcome correlated most significantly with the status of posterior glenoid wear. Patients with concentric, type I glenoids achieved 86% satisfactory results, whereas patients with nonconcentric, type II glenoids had only 63% satisfactory results. Although pain relief was similar in both groups, the unsatisfactory results were attributed to loss of forward elevation and external rotation in patients with type II glenoids. On the basis of these results hemiarthroplasty can be an effective treatment for both primary and secondary arthritis but should be reserved for patients with a concentric glenoid, which affords a better fulcrum for glenohumeral motion.

The inferior glenohumeral ligament (IGHL) is an important structure for maintaining shoulder stability. This study was aimed at determining the geometric and anatomic characteristics of the IGHL and its tensile properties at a higher strain rate than previously tested. Eight fresh-frozen human cadaver shoulders (average age 69 years, age range 62 to 73 years) from four female and four male cadavers were used to harvest bone-ligament-bone specimens from the three regions of the IGHL (superior band, anterior axillary pouch, and posterior axillary pouch). Uniaxial tensile tests were performed at the moderately high strain rate of approximately 10% per second with a servo-hydraulic testing machine. This represented a strain rate that was approximately 100 to 1000 times faster than that previously reported. During tensile testing, bone-ligament-bone strains were calculated from grip-to-grip motion on the testing machine, and mid-substance strains were determined by a video dimensional analyzer. Although all regions of the IGHL had similar lengths (averaging 43.4 mm), their thickness varied by region and by proximal-to-distal location. The superior band was the thickest (2.23 +/- 0.38 mm) of the three regions. Of the remaining two regions the anterior axillary pouch (1.94 +/- 0.38 mm) was thicker than the posterior axillary pouch (1.59 +/- 0.64 mm). By proximal-to-distal location the IGHL was thicker for all three regions near the glenoid (2.30 +/- 0.57 mm) than near the humerus (1.61 +/- 0.52 mm). The superior band had a greater stiffness (62.63 +/- 9.78 MPa) than either the anterior axillary pouch (47.75 +/- 17.89 MPa) or the posterior axillary pouch (39.97 +/- 13.29 MPa). Tensile stress at failure was greater in the superior band (8.4 +/- 2.2 MPa) and the anterior axillary pouch (7.8 +/- 3.1 MPa) than the posterior axillary pouch (5.9 +/- 1.7 MPa). The anterior axillary pouch demonstrated greater bone-to-bone and mid-substance strains (30.4% +/- 4.3% and 10.8% +/- 2.4%, respectively) before failure than the other two regions (superior band: 20.8% +/- 3.8% and 9.1% +/- 2.8%, respectively; posterior axillary pouch: 25.2% +/- 5.8% and 7.8% +/- 2.6%, respectively). Bone-to-bone strain was always greater than mid-substance strain, indicating that when the IGHL is stretched, the tissue near the insertion sites will experience much greater strain than the tissue in the mid-substance. insertion failures were more likely at slower strain rates, and ligamentous failures were predominant at the fast strain rate. When compared with other tensile studies of the IGHL at slower strain rates (0.01% per second and 0.1% per second), the superior band and the anterior axillary pouch demonstrated the viscoelastic effects of increased stiffness and failure stress. This superior band and anterior axillary pouch pouch viscoelastic stiffening effect suggests that these two regions may function to restrain the humeral head from rapid abnormal anterior displacement in the clinically vulnerable position of abduction and external rotation.

Twenty patients underwent surgical reconstruction for nonunion of fractures of the surgical neck of the humerus. Average time from injury to surgery was 10 months (range 4 to 14 months). The operation consisted of bone grafting combined with humeral head replacement in 10 cases and open reduction and internal fixation in 10 cases. Results, at an average follow-up of 51 months (range 24 to 124 months), were excellent in five (25%), satisfactory in six (30%), and unsatisfactory in nine (45%). Twelve nonunions resulted from fractures initially treated with close reduction; repair of these nonunions achieved by 67% excellent or satisfactory results. Eight nonunions resulted from fractures initially treated with internal fixation; repair of these nonunions achieved only 38% excellent or satisfactory results. Fifteen complications, 11 of which necessitated reoperation, occurred. Surgical reconstruction for nonunions of the surgical neck of the humerus usually results in significant improvement in pain but much more modest improvement in active motion and function. Surgery should be reserved for patients with significant symptoms and disability.

Two hundred ten specimens (420 scapulas) from the Hamann-Todd Osteological Collection at the Cleveland Museum of Natural History were evaluated to determine the influence of age on acromial morphologic condition. Equal numbers of specimens from female and male and black and white subjects were evaluated. The length, width, and anterior thickness of the acromion and the acromial facet of the acromioclavicular joint were measured with digital calipers, examined visually, and evaluated radiographically. Distribution of acromial morphologic types was type I, (flat) 32%, type II (curved), 42%, and type III (hooked), 26%. Analysis of the data revealed no consistent, statistically significant impact of age on morphologic condition. The incidence of os acromiale was 8% (17 of 210), with 7 (41%) of 17 specimens having bilateral involvement. Mean acromial dimensions in men were length = 48.5 mm, width = 19.5 mm, and anterior thickness = 7.7 mm. Mean dimensions in women were length = 40.6 mm, width = 18.4 mm, and thickness = 6.7 mm. Multiple regression analysis revealed no significant changes in any dimension with increasing age. Observation of the acromial facet of the acromioclavicular joint revealed 49% were medially inclined, 48% were vertically inclined, and only 3% were laterally inclined in relationship to the sagittal plane. A statistically significant age-related increase in degenerative changes was noted. Anterior acromial spur formation as determined by visual inspection of the acromion was observed in 7% of specimens from patients younger than 50 years compared with 30% of specimens from patients older than 50 years (p < 0.05). Spur formation on the anterior acromion is an age-dependent process. Acromial morphologic condition as evaluated by outlet radiographs is independent of age and appears to be a primary anatomic characteristic. The variations seen in acromial morphologic condition are not acquired from age-related changes and spur formation and thus contribute to impingement disease independent of and in addition to age-related processes.

Seventeen patients who had osteoarthritis of the glenohumeral joint after surgery for glenohumeral instability underwent prosthetic replacement. Thirteen men and four women with an average age of 43 years were studied. The interval from the initial instability repair to prosthetic replacement averaged 16 years. Before the operation all patients had severe functional disability caused by pain and limited range of motion, especially external rotation. Twelve patients underwent total shoulder replacement, and five patients underwent humeral head replacement. At an average follow-up period of 3 years, 13 (77%) satisfactory results and four (23%) unsatisfactory results were obtained. Pain was relieved in 16 (94%) of the 17 patients. Range of motion improved by an average of 37 degrees of elevation and 53 degrees of external rotation. Previous surgery had distorted the anatomy, and special techniques were required to correct anterior soft-tissue contracture and to compensate for posterior glenoid bone loss.

Forty-one patients (41 shoulders) with acromioclavicular joint disease refractory to conservative treatment underwent arthroscopic distal clavicle resection. Thirty-one men and 10 women with an average age of 32 years were studied. The dominant extremity was involved in 68% of the patients. At an average follow-up period of 31 months (range 24 to 49 months), 18 excellent, 16 good, and seven poor results were found. Twenty-seven (93%) of 29 shoulders with acromioclavicular arthritis or osteolysis of the distal clavicle went on to have satisfactory results compared with only seven (58%) of 12 shoulders with previous grade II acromioclavicular separations or acromioclavicular hypermobility. Total amount of bone removal did not correlate with success, if the resection was even. Five reoperations were done; one uneven resection was revised with arthroscopy, and four shoulders underwent acromioclavicular stabilization procedures. The high failure rate in patients with even subtle acromioclavicular instability (42%) suggests that in these cases formal stabilization with ligament reconstruction should be considered in addition to resection of the distal clavicle.

The treatment of 17 chronic, unreduced anterior dislocations of the shoulder was reviewed. Eleven women and six men with on average age of 67 years (range 36 to 88 years) were studied. The duration of dislocation averaged 2.3 years (8 weeks to 8 years). Seven patients were treated without surgery despite severe functional deficits, for reasons of health or motivation. Ten were treated with surgery. One patient with preserved joint surfaces underwent open reduction and corticoid transfer to bone graft an eroded anterior glenoid. Nine patients with destroyed articular surfaces underwent unconstrained replacement orthroplosty. Humeral retroversion was increased for stability. The soft tissues were reattached, and rehabilitation was modified as with a repair of recurrent dislocations. Anterior glenoid erosion was often present and required bone grafting to support the glenoid component in four shoulders. Two chronic rotator cuff tears required repair. Nine patients were followed from 2 to 6 years, with an average of 3.9 years. The results were four excellent, four satisfactory, and one unsatisfactory. Although the reconstruction is complex, the surgical results were clearly superior to those of the nonoperative group., (Copyright © 1993 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)

Twenty-two patients aged 20 to 82 years (average 56 years) were followed for 1.1 to 8.9 years (average 3.3 years) after open reduction and internal fixation of two- and three-part displaced surgical neck fractures of the proximal humerus. There were 14 two-part displaced surgical neck fractures, seven three-part displaced greater tuberosity and surgical neck fractures, and one three-part displaced lesser tuberosity and surgical neck fracture. Fixation was achieved with heavy nonabsorbable sutures or wire that incorporated the rotator cuff tendons, tuberosities, and shaft. In cases with significant surgical neck comminution, humeral Enders nails were incorporated in a tension-band construct to provide longitudinal stability. Eighteen (82%) of the 22 patients had good or excellent results. Three (14%) of the 22 had satisfactory results, and one (5%) had an unsatisfactory result. The use of a technique of limited internal fixation for these displaced fractures without the use of plates and screws achieved fracture stability and a high percentage of acceptable results., (Copyright © 1993 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)

We reviewed a series of 30 shoulders in 25 patients who had glenohumeral arthritis and rotator cuff deficiency and who underwent prosthetic replacement. Nineteen shoulders underwent humeral head replacement, and 11 shoulders had total shoulder arthroplasty. Meticulous mobilization and reconstruction of the deficiencies in the thin atrophic rotator cuff tissues were attempted in all shoulders. Emphasis was placed on anteroposterior stability, and this was achieved in all shoulders; superior coverage was fully achieved in 15 shoulders and was partially achieved in 11. All shoulders had less pain after surgery, and 93% achieved satisfactory pain relief. Total shoulder arthroplasty and humeral hemiarthroplasty were found to provide similar results with respect to pain relief, functional improvement, and patient satisfaction. Shoulders with hemiarthroplasty gained significantly more active elevation (+52° vs + 2°) after surgery. Cuff repair was easier when a humeral head prosthesis alone was used because less lateralization of the humerus occurred. Also, operative time, anesthesia time, and blood loss were decreased with hemiarthroplasty. Because the lack of glenoid resurfacing did not adversely affect pain relief or function and avoided the potential problem of glenoid loosening, we favor humeral hemiarthroplasty as a treatment for glenohumeral arthritis in the rotator cuff-deficient shoulder., (Copyright © 1992 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)