Complete Supraspinatus Tear Research Articles

Long Head of the Biceps Autograft Performs Biomechanically Similar to Human Dermal Allograft for Superior Capsule Reconstruction After Rotator Cuff Tear

To provide a biomechanical comparison between human dermal (HD) allograft and long head of biceps tendon (LHBT) autograft with and without posterior side-to-side suturing for superior capsule reconstruction. Eight fresh-frozen cadaveric shoulder specimens were tested in 5 conditions: (1) intact, (2) complete supraspinatus tear, (3) LHBT, (4) LHBT with side-to-side suturing, and (5) HD allograft with side-to-side suturing. Functional abduction force, superior translation of humeral head, translational range of motion, and rotational range of motion were tested at 0°, 30°, 60°, and 90° of abduction within each condition. Data were analyzed using analysis of variance with post-hoc Tukey testing for pairwise comparison, with a significance value set at .05. Functional abduction force in the LHBT, LHBT+ suture, and HD+ suture conditions was significantly increased compared with the supraspinatus tear condition at abduction angles of 30° (P= .011, .001, and .017, respectively), 60° (P= .004, .001, and .002, respectively), and 90° (P= .013, .001, and .038, respectively). In addition, superior translation of the humeral head in the LHBT, LHBT+ suture, and HD+ suture conditions was significantly decreased compared with the tear condition at abduction angles of 30° (P= .03, .049, .03, respectively) and 60° (P= .02, .04, .03, respectively). All 3 reconstructive techniques were statistically identical to the intact rotator cuff condition in regard to translational and rotational range of motion. Superior capsule reconstruction with LHBT autograft without side-to-side suturing, LHBT with posterior side-to-side suturing, and HD allograft with posterior side-to-side suturing all equivalently restore functional abduction force and decrease superior translation of the humeral head after a complete supraspinatus tear. Superior capsule reconstruction with long head of the biceps tendon autograft and human dermal allograft both restore functional abduction force and decrease superior translation of the humeral head, while displaying no losses in the range of motion in a cadaveric model.

Infraspinatus Muscle Fiber Moment Arms During Abduction: A Biomechanical Comparison of Values for Intact Rotator Cuff, Supraspinatus Tear, Superior Capsular Reconstruction, and Reverse Total Shoulder Arthroplasty.

Background:Lines of action of the superior, middle, and inferior infraspinatus muscle fibers work together to produce moment arms that change throughout abduction in an intact shoulder, after a supraspinatus tear, and after superior capsular reconstruction (SCR) and reverse total shoulder arthroplasty (rTSA).Purpose:To use moment arm values to indicate the efficacy of SCR and rTSA to restore infraspinatus function during shoulder abduction.Study Design:Descriptive laboratory study.Methods:A total of 5 human cadaveric shoulders placed in a testing apparatus were each actively abducted (0°-90°) under the following 4 conditions: intact, complete supraspinatus tear, SCR, and rTSA. The 3-dimensional coordinates of points were tracked along the origin and insertion of the superior, middle, and inferior infraspinatus fibers during abduction. Moment arm values were calculated using the origin-insertion method to determine abduction contribution of infraspinatus fiber sections. Analysis of variance and post hoc Tukey testing were used to compare differences in moment arms between the 4 conditions and between fiber sections.Results:In the intact condition, the superior infraspinatus fibers had an abduction moment that decreased with elevation until shifting to adduction. Conversely, the middle and inferior fibers had an adduction moment that turned to abduction (mean moment arm values from 0° to 90°: inferior, from –5.9 to 19.4 mm; middle, from –4.7 to 15.9 mm; superior, from 5.6 to –5.1 mm; P < .05). After a supraspinatus tear, superior fibers lacked any torque, and inferior and middle fibers lost adduction potential (inferior, from 4.8 to 14.0 mm; middle, from –0.2 to 9.6 mm; superior, from 1.0 to 0.7 mm; P < .05). SCR restored the initial superior fiber abduction moment (5.6 mm at 0°; P < .05); middle and inferior fibers had some restoration but were weaker than intact fibers. Loss of abduction moment in all fibers was seen with rTSA (inferior, from –9.6 to –1.6 mm; middle, from –10.5 to –3.6 mm; superior, from –1.7 to –4.6 mm; P < .05).Conclusion:Infraspinatus fiber groups had different and inverse moment arms during scapular plane elevation. SCR most closely resembled the intact shoulder, whereas rTSA transformed the infraspinatus into an adductor.Clinical Relevance:These results support the efficacy of SCR at restoring biomechanical muscle function and suggest that the changes in moment arms for each fiber group be considered when choosing treatment modalities and rehabilitation protocols after rotator cuff tear.

A Biomechanical Analysis of Shoulder Muscle Excursions During Abduction, After the Treatment of Massive Irreparable Rotator Cuff Tears Using Superior Capsular Reconstruction (SCR), Bursal Acromial Reconstruction (BAR), and SCR with BAR.

IntroductionCurrent understanding of the biomechanical effects of treatment options for irreparable rotator cuff (RC) tears is lacking. This study examines how shoulder muscle lengths and excursions are affected by superior capsular reconstruction (SCR), bursal acromial reconstruction (BAR), and SCR with BAR, following a complete supraspinatus tear.MethodSix fresh-frozen cadaveric shoulders were examined. Deltoid and RC muscle lengths were measured at 0, 30, 45, 60, and 90° of shoulder abduction under six conditions: (1) intact, (2) partially torn supraspinatus, (3) completely torn supraspinatus, (4) SCR, (5) SCR with BAR, and (6) BAR. Muscle excursions from 0–90° of abduction were then calculated.ResultsSubscapularis muscle lengths after SCR, BAR, and SCR with BAR were significantly greater (post-hoc Tukey HSD test; p < .01) compared to the other conditions. Supraspinatus, infraspinatus, teres minor, and deltoid lengths were not significantly different (ANOVA test; p > .01) between the conditions. All muscle excursions remained statistically similar between the conditions (ANOVA test; p > .01).ConclusionThese findings demonstrate that the use of SCR, BAR, or SCR with BAR for a complete supraspinatus tear, may increase subscapularis muscle length while maintaining other shoulder muscle lengths. An increase in subscapularis length can allow for more effective subscapularis muscle strengthening and increased compensatory function in the long term. Additionally, all shoulder muscle excursions are preserved after partial or complete supraspinatus tears and after SCR, BAR, or SCR with BAR. Therefore, these surgical treatments can initially normalize shoulder muscle function during 0–90° of abduction, after an irreparable supraspinatus tear.

Muscle Fiber Contribution to Rotator Cuff Moment Arms During Abduction for Intact Rotator Cuff, Complete Supraspinatus Tear, Superior Capsular Reconstruction, and Reverse Shoulder Arthroplasty. (225)

Objectives:The Rotator Cuff (RC) is formed from the subscapularis, supraspinatus, infraspinatus, and teres minor muscles and their tendinous extensions. The 4 RC tendons insert on the humeral head such that they contribute to the dynamic stability of the glenohumeral joint along with their rotational actions on the shoulder. The moment arm can be used to demonstrate the work effort potential that a specific muscle is contributing to a musculoskeletal joint rotation. The objective of this study was to break out RC muscles into multiple fibers, providing more clarity as to how individual fibers contribute to a muscle’s overall moment arm during abduction.The aims of this study are: 1.) to illustrate within each RC muscle how multiple muscle fiber lines of action work together to produce abduction in an intact shoulder 2.) to estimate the moment arm changes that take place when the intact rotator cuff goes through surgical repair with either SCR or RSA after complete supraspinatus tear. We hypothesized that the rotator cuff muscles work differently and in combination at the fiber level to bring about a resultant movement that can be assessed through the proposed method of moment arm calculation for intact RC, complete supraspinatus tear, SCR and RSA.Methods:Five fresh cadaveric shoulder specimens were used in an apparatus where each muscle was maintained in tension with the line of action towards its origin on the scapula (Figure 1). An Optotrack camera kept track of digitized points along both the origin and insertion of the rotator cuff muscles as the shoulder was abducted. Using these digitized points, multiple lines of action were created across the breadth of each muscle. Each muscle force action line was then used to calculate moment arm values during 0-90º abduction (Figure 2).Results:Moment arms calculated for multiple fiber lines spanning the tendon attachment site displayed the variance of fiber contribution and function within each muscle during abduction. Our results indicate that rather than providing a return to anatomical shoulder muscle function, RSA and SCR models produce moment arms that vary between muscles, with some contributing more to abduction and some contributing less. Highlighted below are the infraspinatus results for moment arms of individual fiber lines of action (Figure 3) and calculated mean moment arms (Figure 4) over abduction.ANOVA testing demonstrated a significant difference (p<0.001) when analyzing moment arms of intact, complete supraspinatus tear, SCR, and RSA models in teres minor and infraspinatus. There was no significant difference in moment arm values between the models in the subscapularis (p=0.148). Highlighted in Table 1 are the ANOVA testing results for infraspinatus.Conclusions:Our biomechanical analysis demonstrated sufficient sensitivity to detect differences in moment arms of the four rotator cuff muscles across a variety of models, suggesting changes to even one muscle of the shoulder will have significant implications on the function of other shoulder muscles. Furthermore, our analysis of fiber divisions within the same muscle illustrates the complex nature of the shoulder muscles themselves, and future studies should aim to better explore and model their function. The calculated percent differences from intact beautifully illustrated this complexity, as corrective RSA and SCR procedures provided better resemblance of intact anatomy within some rotator cuff muscles while creating a larger percent difference in other muscle groups.By breaking out RC muscles into multiple fibers, more clarity can be gained as to how individual fibers contribute to a muscle’s overall moment arm during abduction. This may further aid surgical decision-making, specifically for RSA where there is continued debate about whether to reconstruct portions of the RC. Given that the supraspinatus tendon is the most frequently torn tendon in the rotator cuff, especially for athletes who apply repetitive stress to the tendon, the results of this study may help inform post-operative rehabilitation by illustrating how abduction and stability are achieved after SCR and RSA.

Evaluation of rotator cuff abduction moment arms for superior capsular reconstruction and reverse total shoulder arthroplasty.

The rotator cuff (RC) muscles contribute to dynamic stability and rotational actions of the glenohumeral joint. Moment arm can be used to demonstrate the potential work a muscle contributes to a musculoskeletal joint rotation. This study aimed to understand the moment arm contributions of the RC muscles and explore changes following a complete supraspinatus tear treated with either superior capsular reconstruction (SCR) or reverse total shoulder arthroplasty (rTSA). Five fresh-frozen cadaveric specimens were prepared and mounted in an apparatus where each intact RC muscle was held in tension with a line of action toward its origin on the scapula. Mean moment arms for each muscle were determined experimentally based on Optotrak data collected during cadaveric shoulder arm abduction. Using ANOVA testing, our analysis demonstrated significant differences (p < 0.001) in infraspinatus and teres minor moment arms after rTSA compared to the intact shoulder model. After SCR, significant differences (p < 0.001) were seen in teres minor, with these differences being statistically similar to the changes seen in teres minor after rTSA. Subscapularis showed no significant difference in moment arm values between the models (p = 0.148). Our results illustrate that mean moment arms were preserved in the RC muscles after complete supraspinatus tear. This study also shows evidence that subscapularis function may be maintained after SCR or rTSA. After SCR, infraspinatus may maintain similar abduction ability compared to the anatomical shoulder, while teres minor ability may increase. Infraspinatus may have decreased abduction ability after rTSA while teres minor may have increased ability.

Biomechanics in an Incomplete Versus Complete Supraspinatus Tear: A Cadaveric Study.

Background:Degenerative and traumatic changes to the rotator cuff can result in massive and irreparable rotator cuff tears (RCTs).Purpose/Hypothesis:The study objective was to conduct a biomechanical comparison between a small, incomplete RCT and a large, complete RCT. We hypothesized that the incomplete supraspinatus (SS) tear would lead to an incremental loss of abduction force and preserve vertical position of the humeral head, while a complete SS tear would cause superior humeral migration, decrease functional deltoid abduction force, and increase passive range of motion (ROM).Study Design:Controlled laboratory study.Methods:Six cadaveric shoulders were evaluated using a custom testing apparatus. Each shoulder was subjected to 3 conditions: (1) intact/control, (2) 50%, full-thickness, incomplete SS tear, and (3) 100%, complete SS tear. Deltoid abduction force, superior humeral head migration, and passive ROM were measured in static conditions at 0°, 30°, and 60° of glenohumeral abduction, respectively.Results:The intact SS resulted in a mean deltoid abduction force of 2.5, 3.3, and 3.8 N at 0°, 30°, and 60° of abduction, respectively. Compared with the intact shoulder, there was no significant difference in mean abduction force seen in the incomplete tear, while the force was significantly decreased by 52% at 30° of abduction in the complete tear (P = .009). Compared with the incomplete tear, there were significant decreases in abduction force seen in the complete tear, by 33% and 48% (0.9 N and 1.1 N) at 0° and 30° of abduction, respectively (P = .04 and .004). The intact configuration experienced a mean superior humeral head migration of 1.5, 1.4, and 1.1 mm at 0°, 30°, and 60° of abduction, respectively. The complete tear resulted in a superior migration of 3.0 and 4.4 mm greater than the intact configuration at 0° and 30° of abduction, respectively (P = .001). There was a 5° and 10° increase in abduction ROM with 50% and 100% tears, respectively (P = .003 and .03).Conclusion:An incomplete SS tear does not significantly alter the biomechanics of the shoulder, while a large, complete SS tear leads to a significant superior humeral migration, a decreased deltoid abduction force, and a mild increase in passive ROM.Clinical Relevance:Our findings demonstrate the effects of large SS tears on key biomechanical parameters, as they progress from partial tears.

Complete supraspinatus tear with greater tuberosity fracture in a 14-year-old boy: Case report and review of literature

There are several possible etiologies for rotator cuff pathology, which vary based on age and sports participation. We are reporting a case of complete supraspinatus tear with associated greater tuberosity fracture in a 14-year-old boy, and to the best of our knowledge, this is the first case of complete supraspinatus tear with greater tuberosity fracture in a boy younger than 15 years.

The influence of partial subscapularis tendon tears combined with supraspinatus tendon tears

With the advent of arthroscopy, more partial subscapularis tears are being recognized. The biomechanical effects of partial subscapularis tears are unknown, and there is no consensus as to their treatment. Therefore, the objective of this study was to evaluate and to quantify the changes in range of motion and glenohumeral kinematics for isolated subscapularis partial tears, combined subscapularis and supraspinatus tears, supraspinatus repair, and combined supraspinatus and subscapularis repair. Six cadaveric shoulders were tested in the scapular plane with 0°, 30°, and 60° shoulder abduction under 6 conditions: intact; ¼ subscapularis tear; ½ subscapularis tear; ½ subscapularis and complete supraspinatus tear; supraspinatus repair; and supraspinatus and subscapularis repair. Maximum internal and external rotation and glenohumeral kinematics were measured under physiologic muscle loading condition. A repeated measures analysis of variance with a Tukey post hoc test was used for statistical analysis. Maximum external rotation was significantly increased after ¼ subscapularis tear at 30° abduction and in all abduction angles with ½ subscapularis tear (P < .05). The 2 repair conditions did not restore external rotation to the intact level. At maximum internal and external rotation, there was a significant superior shift in the humeral head apex position with ¼ subscapularis tear at 30° abduction and with ½ subscapularis tear at 60° abduction (P < .05). Repair of the supraspinatus tendon partially corrected abnormal kinematics; however, neither repair restored abnormal kinematics to intact. Additional repair of the partial subscapularis tear with supraspinatus tear did not affect external rotation or glenohumeral kinematics. Further studies are needed to evaluate different subscapularis repair techniques. Basic science study, biomechanics.

Rotator cuff tears after 70 years of age: A prospective, randomized, comparative study between decompression and arthroscopic repair in 154 patients

Arthroscopic repair of rotator cuff tears leads to better clinical outcomes than subacromial decompression alone; however the former is rarely proposed to patients above 70 years of age. Our hypothesis was that arthroscopic repair would be superior to decompression in patient 70 years or older. The primary goal was to compare the clinical results obtained with each technique. The secondary goal was to analyze the effects of age, tendon retraction and fatty infiltration on the outcome. This was a prospective, comparative, randomized, multicenter study where 154 patients were included who were at least 70 years of age. Of the included patients, 143 (70 repair and 73 decompression) were seen at one-year follow-up; these patients had an average age of 74.6 years. Shoulders had a complete supraspinatus tear with extension limited to the upper-third of the infraspinatus and Patte stage 1 or 2 retraction. Clinical outcomes were evaluated with the Constant, ASES and SST scores. All scores improved significantly with both techniques: Constant +33.81 (P<0.001), ASES +52.1 (P<0.001), SST +5.86 (P<0.001). However, repair led to even better results than decompression: Constant (+35.85 vs. +31.8, P<0.05), ASES (+56.09 vs. +48.17, P=0.01), SST (+6.33 vs. +5.38, P=0.02). The difference between repair and decompression was not correlated with age; arthroscopic repair was also better in patients above 75 years of age (Constant, ASES and SST scores P<0.01). There was no significant correlation between the final outcomes and initial retraction: Constant (P=0.14), ASES (P=0.92), SST (P=0.47). The difference between repair and decompression was greater in patients with stages 0 and 1 fatty infiltration (Constant P<0.02) than in patients with stages 2 and 3 fatty infiltration (Constant P<0.05). There was a significant improvement in all-clinical scores for both techniques 1 year after surgery. Repair was significantly better than decompression for all clinical outcomes, even in patients above 75 years of age. The difference observed between repair and decompression was greater in patients with more retracted tears and lesser in patients with more severe fatty infiltration.

Ability to Return to Play After Arthroscopic Shoulder Surgery in Professional Female Tennis Players

Ability to Return to Play After Arthroscopic Shoulder Surgery in Professional Female Tennis Players

Perception sensorielle chez les sujets présentant des troubles du sommeil

Arthroscopic repair of rotator cuff tears leads to better clinical outcomes than subacromial decompression alone; however the former is rarely proposed to patients above 70 years of age. Our hypothesis was that arthroscopic repair would be superior to decompression in patient 70 years or older. The primary goal was to compare the clinical results obtained with each technique. The secondary goal was to analyze the effects of age, tendon retraction and fatty infiltration on the outcome.This was a prospective, comparative, randomized, multicenter study where 154 patients were included who were at least 70 years of age. Of the included patients, 143 (70 repair and 73 decompression) were seen at one-year follow-up; these patients had an average age of 74.6 years. Shoulders had a complete supraspinatus tear with extension limited to the upper-third of the infraspinatus and Patte stage 1 or 2 retraction. Clinical outcomes were evaluated with the Constant, ASES and SST scores.All scores improved significantly with both techniques: Constant +33.81 (P < 0.001), ASES +52.1 (P < 0.001), SST +5.86 (P < 0.001). However, repair led to even better results than decompression: Constant (+35.85 vs. +31.8, P < 0.05), ASES (+56.09 vs. +48.17, P = 0.01), SST (+6.33 vs. +5.38, P = 0.02). The difference between repair and decompression was not correlated with age; arthroscopic repair was also better in patients above 75 years of age (Constant, ASES and SST scores P < 0.01). There was no significant correlation between the final outcomes and initial retraction: Constant (P = 0.14), ASES (P = 0.92), SST (P = 0.47). The difference between repair and decompression was greater in patients with stages 0 and 1 fatty infiltration (Constant P < 0.02) than in patients with stages 2 and 3 fatty infiltration (Constant P < 0.05).There was a significant improvement in all-clinical scores for both techniques 1 year after surgery. Repair was significantly better than decompression for all clinical outcomes, even in patients above 75 years of age. The difference observed between repair and decompression was greater in patients with more retracted tears and lesser in patients with more severe fatty infiltration.II (prospective, randomized study with low power).

Arthroscopic Shoulder Surgery in Female Professional Tennis Players

Objectives:Recent publications have highlighted the relatively poor outcome of other overhead athletes, particularly baseball players, with regard to return to sports at the same or higher level after shoulder surgery. However, true assessment of their ability when returning to sport is not as clear. Further, ability to return to other overhead sports has not been reported. Our objective was to assess outcome and time to return to previous level of function following shoulder surgery in professional tennis players.Methods:The records of all female tennis players on the Women’s Tennis Association (WTA) professional circuit between January 2008 and June 2010 were reviewed to identify players who underwent shoulder surgery on their dominant (serving) shoulder. Details of the surgery including date, procedures performed, and complications were recorded. The primary outcomes were ability and time to return to professional play, and if they were able to return to their previous level of function, as determined by singles ranking. Pre and post-operative singles rankings were used to determine rate and completeness of return to preoperative function. Their highest ranking pre-injury, post operatively, and the time to return to pre-injury ranking were evaluated.Results:During the study period eight professional women tennis players from the WTA underwent shoulder surgery on their dominant arm. All surgery was performed arthroscopically, 7 out of 8 players had more than one procedure performed during the surgery. In total, 3 players underwent debridement of a partial rotator cuff tear and 2 players underwent repair of a complete supraspinatus tear. Three players had an anterior labral repair or reconstruction for anterior instability, and one player underwent repair of a SLAP lesion. Two players underwent neurolysis of a suprascapular nerve, and three players in total underwent a subacromial decompression. All players (100%) returned to professional play. The mean time to return to play was 6.7 months after surgery. However, only 25% (2 out of 8) players had achieved their pre-injury singles rank or better by 18 months post operatively. In total, three players returned to their pre-injury singles ranking, with their peak singles ranking being attained at a mean of 2.5 years post operatively.Conclusion:This study demonstrates that in professional female tennis players, a high return to play rate following arthroscopic shoulder surgery is also associated with a prolonged and often incomplete return to previous level of performance. Thus, counselling the patient to this fact is important to manage their expectations.

Rabbit supraspinatus motor endplates are unaffected by a rotator cuff tear

Rotator cuff tears are a major cause of morbidity. Following rotator cuff tears, muscle atrophy and fatty infiltration begin in the tissue, limiting repair potential and leading to a higher re-tear rate and a worse functional outcome. We evaluated whether fatty degeneration resulting from a complete supraspinatus tear with retraction is associated with an injury to the suprascapular nerve. Four skeletally mature New Zealand white rabbits were randomized to receive an index procedure on either their right or left shoulder with the opposite shoulder serving as a control. At the index procedure, the supraspinatus tendon was transected at its insertion and allowed to retract. At 3 months, the rabbits were euthanized, and both supraspinatus muscles were harvested. The specimens were then examined with confocal microscopy and histology. Atrophy was grossly visible in all four test muscles, and fatty infiltration was confirmed with osmium tetroxide staining. In all four rabbits, the degree of denervation (p = 0.71) and partial denervation (p = 0.91) was not significantly different between control and experimental muscle. Rotator cuff tear does not affect the motor endplate or innervation status of the supraspinatus. Fatty infiltration occurs independent of denervation of the supraspinatus.

The Presence of Fatty Infiltration in the Infraspinatus: Its Relation With the Condition of the Supraspinatus Tendon

We aim to determine the prevalence of fatty infiltration and tears in the infraspinatus and to identify any associated risk factors. Shoulder magnetic resonance imaging scans from 2006 to 2009 were reviewed. Arthrograms, inflammatory arthropathies, neoplasms, and fractures were excluded. Rotator cuff tears were graded in 4 categories: no tear, partial tear, and complete tear with and without retraction. Fatty infiltration was graded by radiologists using the modified Goutallier classification. Supraspinatus muscle atrophy (size) was measured by use of the ratio of the cross-sectional area of the muscle to the supraspinatus fossa on a sagittal T1-weighted sequence. Three hundred seventy-seven scans were included. The prevalence of infraspinatus tears was as follows: no tear, 74.8%; partial tear, 17.5%; complete tear, 3.2%; and complete tear with retraction, 4.5%. Fatty infiltration of grade 2 or higher was found in 18.1% of the infraspinatus without tears, 39.4% with partial tears, 66.7% with a complete tear, and 82.4% with a complete tear with retraction. In the infraspinatus without tears, increasing fatty infiltration was correlated with the severity of a concomitant supraspinatus tear. Fatty infiltration of grade 2 or higher in the infraspinatus without tears was found in 7.8% of shoulders with an intact supraspinatus, 18.6% with a partial supraspinatus tear, 23.5% with a complete supraspinatus tear, and 54.6% with a retracted complete supraspinatus tear. Supraspinatus muscle atrophy was correlated with infraspinatus fatty infiltration. Increased infraspinatus fatty infiltration was correlated with the severity of an infraspinatus tear. However, substantial fatty infiltration of the infraspinatus was seen even in the absence of a tear, and it was correlated with a worsening severity of a concomitant supraspinatus tear and atrophy. Concern over tear progression and increasing fatty infiltration of the infraspinatus may impact the management of isolated supraspinatus tendon tears. Level IV, prognostic case series.

Incidence of Associated Injuries with Acute Acromioclavicular Joint Dislocations Types III through V

Background Traumatic acromioclavicular (AC) joint dislocations are common injuries among the active population. The injury mechanism requires excessive force delivered by a fall or blow to the shoulder. Associated injuries may occur and remain undetected if they are masked by the painful and prominent AC joint injury. Hypothesis Intra-articular injuries associated with high-grade AC joint dislocations are common. Study Design Case series; Level of evidence, 4. Methods Between 2002 and 2007, 77 patients (68 male, 9 female; average age, 35.5 years; range, 17-62 years) were surgically treated for acute AC joint dislocations (Rockwood type III, 5; type IV, 30; and type V, 42). All patients underwent diagnostic glenohumeral joint arthroscopy. Concomitant intra-articular injuries were identified and treated. Results Intra-articular injuries were found in 14 of 77 patients (18.2%). Superior labral anterior posterior (SLAP) lesions were observed in 11 of 77 patients 14.3% (SLAP I, 3; II, 2; III, 3; and IV, 3). Nineteen percent of Rockwood V lesions had associated SLAP lesions (SLAP I excluded), whereas only 3.4% of Rockwood IV lesions showed SLAP lesions. A complete supraspinatus tear was detected in 1 case, and partial articular-sided supraspinatus tears were detected in 2 cases. Four patients sustained an accompanying fracture. Conclusion Concomitant injuries to the shoulder girdle obtained during traumatic AC joint separation may be more frequent than previously thought. Clinical diagnosis may be difficult in the setting of an acute and painful dislocated AC joint. Shoulder arthroscopy during arthroscopic AC joint stabilization may aid in detecting associated injuries.

양측 견관절을 침범한 거울 병변 -머리 위의 작업을 하는 근로자 대상 관절경적 연구

Purpose: To demonstrate arthroscopically the presence of bilateral shoulder due to overhead work. Materials and Methods: A cross-sectional study was performed in a historical cohort of 10 male tire plant workers who underwent MRI studies of both shoulders. Bilateral intraarticular shoulder pathology was diagnosed by magnetic resonance imaging and confirmed by arthroscopy. Mirror were defined as similar pathology between an individual patient`s two shoulders. Results: We report on ten patients who had bilateral lesions. The most common mirror lesions were tears of the rotator cuff. Most patients (7 of 10) had more than one mirror lesion in their shoulders. There were two bilateral full thickness tears involving the supraspinatus and infraspinatus, four bilateral partial thickness supraspinatus tears, six bilateral partial or upper corner lesion complete subscapularis tears, and one bilateral complete supraspinatus tear. Conclusion: Occupational overhead work with simultaneous use of both arms is associated with bilateral shoulder lesions verified by arthroscopy. By demonstrating the work-related bilateral shoulder involvement, this study suggests an etiopathogenesis for these lesions and provides rational for developing worksite prevention strategies.

Tendon-Bone Interface Motion in Transosseous Suture and Suture Anchor Rotator Cuff Repair Techniques

Background Although many studies involving rotator cuff repair fixation have focused on ultimate fixation strength and ability to restore the tendon's native footprint, no studies have characterized the stability of the repair with regard to motion between the tendon and repair site footprint. Hypothesis Suture anchor fixation for rotator cuff repair has greater interface motion between tendon and bone than does transosseous suture fixation. Study Design Controlled laboratory study. Methods Twelve fresh-frozen human cadaveric shoulders were tested in a custom device to position the shoulder in internal and external rotations with simulated supraspinatus muscle loading. Tendon motion relative to the insertional footprint on the greater tuberosity was determined optically using a digital camera rigidly connected to the humerus, with the humerus positioned at 60° of internal rotation and 60° of external rotation. Testing was performed for the intact tendon, a complete supraspinatus tear, a suture anchor repair, and a transosseous tunnel repair. Results Difference in tendon-bone interface motion when compared with the intact tendon was 7.14 ± 3.72 mm for the torn rotator cuff condition, 2.35 ± 1.26 mm for the suture anchor repair, and 0.02 ± 1.18 mm for the transosseous suture repair. The transosseous suture repair demonstrated significantly less motion when compared with the torn rotator cuff and suture anchor repair conditions (P <. 05). Conclusion Transosseous suture repair compared with suture anchor repair demonstrated superior tendon fixation with reduced motion at the tendon-to-tuberosity interface. Clinical Relevance Development of new fixation techniques for arthroscopic and open rotator cuff repairs should attempt to minimize interface motion of the tendon relative to the tuberosity.

The effect of rotator cuff tears on reaction forces at the glenohumeral joint

The rotator cuff muscles maintain glenohumeral stability by compressing the humeral head into the glenoid. Disruption of the rotator cuff compromises concavity compression and can directly affect the loads on the glenohumeral joint. The purpose of this study was to quantify the effect of rotator cuff tears on the magnitude and direction of glenohumeral joint reaction forces during active shoulder abduction in the scapular plane using nine cadaveric upper extremities. Motion of the full upper extremity was simulated using a dynamic shoulder testing apparatus. Glenohumeral joint reaction forces were measured by a universal force–moment sensor. Five conditions of rotator cuff tears were tested: Intact, Incomplete Supraspinatus Tear, Complete Supraspinatus Tear, Supraspinatus/Infraspinatus Tear, and Global Tear. Reaction forces at the glenohumeral joint were found to steadily increase throughout abduction and peaked at maximum abduction for all conditions tested. There were no significant differences in reaction force magnitude for the intact condition (337±88 N) or those involving an isolated incomplete tear (296±83 N) or complete tear (300±85 N) of the supraspinatus tendon. Extension of tears beyond the supraspinatus tendon into the anterior and posterior aspect of the rotator cuff led to a significant decrease in the magnitude of joint reaction force (126±31 N) . Similarly, such tears resulted in a significant change in the direction of the reaction force at the glenohumeral joint. These results suggest that joint reaction forces are significantly affected by the integrity of the rotator cuff, specifically, by the transverse force couple formed by the anterior and posterior aspects of the cuff. The quantitative data obtained in this study on the effect of rotator cuff tears on magnitude and direction of the reaction force at the glenohumeral joint helps clarify the relationship between joint motion, joint compression and stability.