Location and Size of the Reverse Hill-Sachs Lesion in Patients with Traumatic Posterior Shoulder Instability.

BACKGROUND: In patients with traumatic posterior shoulder instability, little is known about the precise location and size of the reverse Hill-Sachs lesion. METHODS: Forty-nine shoulders of 47 patients with traumatic posterior instability were included in this study based on the following inclusion criteria: 1) a primary or recurrent traumatic posterior shoulder dislocation, and 2) the initial event was caused by trauma. Patients were excluded if they had: 1) no history of trauma, 2) prior shoulder surgery, 3) no CT examination, or 4) seizure cases. Three-dimensional images of the humerus reconstructed from CT images were reviewed using an image analysis software. The location and size of the reverse Hill-Sachs lesion were measured and described on a clock face on the humeral head. RESULTS: The reverse Hill-Sachs lesion was observed in 25 of 49 shoulders (51%). The reverse Hill-Sachs lesions were located between 1:37 and 2:48. The depth of the reverse Hill-Sachs lesion (mean ± SD) was 5.8 ± 2.2 mm. The extent of the reverse Hill-Sachs lesion was 35° ± 12°. The average orientation of the reverse Hill-Sachs lesion, represented by an angle measured from the 12 o'clock position, was 64° ± 12° and pointing towards 2:09 on a clock face. Length and width of reverse Hill-Sachs lesions were 9.7 ± 4.7 mm, 11.1 ± 3.6 mm, respectively. CONCLUSION: The reverse Hill-Sachs lesion was a semicircular compression fracture located on the anteromedial aspect of the humeral head. Compared with shoulders with anterior shoulder instability, the humeral defect was smaller and located more inferiorly in shoulders with posterior instability.

Editorial Commentary: Superior Capsule Reconstruction: Acellular Allograft at 45° of Glenohumeral Abduction Improves Glenohumeral Stability, but Fascia Lata Autograft Remains Superior.

Originally, fascia lata autograft was used for superior capsule reconstruction (SCR) to restore glenohumeral stability in irreparable rotator cuff tears. Consistently excellent clinical outcomes with low graft tear rates have been reported, without repair of tears in the supraspinatus and infraspinatus tendons. On the basis of our experience and studies published in the 15 years since the first SCR using fascia lata autograft in 2007, we can say that this technique is the gold standard. SCR using fascia lata autograft can cover all irreparable rotator cuff tears (Hamada grade 1-3; although the indication for SCR using other grafts, including dermal allograft, biceps, and hamstrings, is only Hamada grade 1 or 2); creates excellent clinical outcomes with low graft tear rates in short-term, long-term, and multicenter studies; regenerates the fibrocartilaginous insertions at both the greater tuberosity and superior glenoid according to histological study; and enables complete restoration of shoulder stability and subacromial contact pressure in cadaveric biomechanical studies. In some countries, dermal allograft is preferred for SCR. However, high rates of graft tear and complications have been reported after SCR using dermal allografts, even in limited indications of irreparable rotator cuff tears (Hamada grade 1 or 2). This high failure rate results from the lack of stiffness and thickness of the dermal allograft. Dermal allografts in SCR can be elongated by 15% after only a couple of physiological shoulder movements, whereas fascia lata graft cannot. This 15% graft elongation, which creates less glenohumeral stability and high graft tear after SCR, is a fatal problem of dermal allograft for SCR in irreparable rotator cuff tears. Current research suggests that SCR using dermal allografts is not strongly recommended for the treatment of irreparable rotator cuff tears. Dermal allograft probably should be used only for augmentation of rotator cuff complete repair.

Structural and clinical outcomes after superior capsule reconstruction using an at least 6-mm-thick fascia lata autograft including the intermuscular septum.

BACKGROUND: Superior capsule reconstruction (SCR) is a viable treatment option for irreparable rotator cuff tears. However, graft tear rate is highly variable in the previous studies, and the impact of graft tears on clinical outcomes after arthroscopic SCR remains controversial. We aimed to investigate the graft tear rate, timing of graft tear, and the impact of graft tears on clinical outcomes after arthroscopic SCR using an at least 6-mm-thick fascia lata autograft including the intermuscular septum. METHODS: This retrospective multi-institutional study included 154 patients (79 women and 75 men; mean age, 69.9 yr; age range, 49-87 yr) with irreparable rotator cuff tears who underwent arthroscopic SCR using an at least 6-mm-thick fascia lata autograft including the intermuscular septum and completed a minimum 2-year follow-up. Postoperative graft integrity was evaluated by magnetic resonance imaging examinations performed at 3, 6, 12, and 24 mo after surgery. The presence of a full-thickness defect within the graft was diagnosed as a graft tear. In contrast, a graft without a full-thickness defect was diagnosed as a healed graft. We compared the following data between patients with and without graft tears: (1) baseline characteristics, (2) visual analog scale pain score, (3) Japanese Orthopaedic Association score, (4) American Shoulder and Elbow Surgeons shoulder score, and (5) active range of motion. RESULTS: The overall graft tear rate was 11.7% (18 of 154 patients). Of 18 graft tears, 14 (77.8%) occurred within 6 mo after SCR. Two additional graft tears were diagnosed at 12 mo postoperatively and another 2 at 24 mo after SCR. The visual analog scale, American Shoulder and Elbow Surgeons, and Japanese Orthopaedic Association scores improved significantly after SCR in both patients with and without graft tears (all P < .0001). However, patients with graft tears showed significantly inferior postoperative visual analog scale, American Shoulder and Elbow Surgeons, and Japanese Orthopaedic Association scores (1.9, 75.2, and 77.4, respectively) than those without graft tears (0.5, 93.1, and 92.3, respectively; all P < .01). CONCLUSIONS: The overall graft tear rate after arthroscopic SCR using an at least 6-mm-thick fascia lata autograft including the intermuscular septum was low (11.7%), relatively to that reported in previous studies. The majority of graft tears (77.8%) occurred within 6 mo after SCR. Graft healing was associated with more favorable clinical outcomes after SCR.

Postoperative graft integrity affects clinical outcomes after superior capsule reconstruction using fascia lata autograft in posterior-superior rotator cuff tears: a multicenter study.

BACKGROUND: Previous studies have postulated that graft thickness and graft healing may be important factors for optimizing clinical outcomes of superior capsule reconstruction (SCR) for patients with irreparable rotator cuff tears (RCTs). However, the relationship between postoperative graft integrity and clinical outcomes after SCR remains unclear. We aimed to assess the relationship between postoperative graft integrity, including graft thickness and size of graft tear, and clinical outcomes after SCR in patients with irreparable RCTs. METHODS: This retrospective multicenter study included 188 patients (86 women, 102 men; mean age, 69.2 years; range, 49-87 years) with irreparable RCTs who underwent arthroscopic SCR using fascia lata autografts. Using magnetic resonance imaging, the graft integrity was evaluated postoperatively at or after 1 year and was classified, according to Hasegawa's classification, into 4 categories: type I-II, intact graft of sufficient thickness; type III, thinned graft without discontinuity; type IV, presence of a minor discontinuity; and type V, presence of a major discontinuity. We compared (1) baseline characteristics, (2) visual analog scale (VAS) for pain, (3) American Shoulder and Elbow Surgeons (ASES) score, (4) active shoulder range of motion, and (5) acromiohumeral distance (AHD) among 4 groups based on postoperative graft integrity. RESULTS: Magnetic resonance imaging scans revealed 152 shoulders (80.9%) with type I-II graft, 13 (6.9%) with type III graft, 13 (6.9%) with type IV graft, and 10 (5.3%) with type V graft. VAS and ASES scores significantly improved after SCR in all graft types (P < .0001 to P = .02). However, shoulders with type V grafts had significantly inferior postoperative VAS and ASES scores compared to those with type I-II grafts (P = .001 and P < .0001, respectively). Shoulders without graft tears (types I-II and III) showed significant improvements in shoulder elevation and internal rotation after SCR (P < .0001 to P = .02). In contrast, shoulders with large graft tears (type V) showed no significant improvement in shoulder range of motion. Postoperative acromiohumeral distance significantly increased only in shoulders with type I-II grafts (P < .0001). CONCLUSION: Postoperative graft thickness and size of graft tear affected clinical and radiographic outcomes after SCR using a fascia lata autograft. Patients with large graft tears had significantly inferior postoperative clinical scores compared to those with intact grafts of sufficient thickness, although arthroscopic SCR provided pain relief even in patients with graft tears. Shoulders with intact grafts of sufficient thickness restored glenohumeral stability and showed better clinical outcomes than those with graft thinning or tears.

Superior Capsule Reconstruction Using Fascia Lata Allograft Compared With Double- and Single-Layer Dermal Allograft: A Biomechanical Study.

PURPOSE: To biomechanically characterize superior capsule reconstruction (SCR) using fascia lata allograft, double-layer dermal allograft, and single-layer dermal allograft for a clinically relevant massive irreparable rotator cuff tear involving the entire supraspinatus and 50% of the infraspinatus tendons. METHODS: Eight cadaveric specimens were tested in 0°, 30°, and 60° abduction for (1) intact, (2) massive rotator cuff tear, (3) SCR using fascia lata, (4) SCR using double-layer dermis, and (5) SCR using single-layer dermis. Superior translation and subacromial contact pressure were measured. Statistical analysis was conducted using repeated measures ANOVA or paired t test with P < .05. RESULTS: Massive rotator cuff tear significantly increased superior translation of the humeral head at all abduction angles (P < .05). At 0° abduction, all SCR conditions significantly decreased superior translation compared with the massive tear but did not restore translation (P < .05) to intact. Fascia lata and double-layer dermis SCR restored superior translation to intact at 30° and 60° of abduction, but single-layer dermis did not. Subacromial contact pressure at 0° of abduction significantly decreased with SCR with fascia lata and double-layer dermis compared with tear. At 30°, all SCR conditions significantly decreased subacromial contact pressure. Single-layer dermis graft thickness significantly decreased more than fascia lata during testing (P = .02). CONCLUSION: For SCR tensioned at 20° glenohumeral abduction, all 3 graft types may restore superior translation and subacromial contact pressure depending on the glenohumeral abduction angle; fascia lata and double-layer dermis may be more effective than single-layer dermis. CLINICAL RELEVANCE: If a dermal graft is to be used for SCR, consideration should be given to doubling the graft for increased thickness and better restorative biomechanical properties, which may improve clinical outcomes following SCR.

Does the timing of surgical intervention impact the clinical outcomes and overall duration of symptoms in frozen shoulder?

BACKGROUND: The optimal timing of arthroscopic capsular release in patients with frozen shoulder is controversial. Some surgeons delay surgery in the belief that early surgical intervention results in a poorer prognosis. However, whether early surgical intervention causes inferior clinical outcomes and a longer duration of symptoms in frozen shoulder remains unclear. The objective of this study was to compare the clinical outcomes and overall duration of symptoms in frozen shoulder between patients who underwent early surgical intervention and those subjected to late surgical intervention. Our hypotheses were that (1) early surgical intervention would provide significant improvement in symptoms but inferior clinical outcomes because of more severe synovitis compared with late surgical intervention and (2) early surgical intervention would shorten the overall duration of symptoms compared with late surgical intervention. METHODS: We reviewed 60 consecutive patients with frozen shoulder who underwent arthroscopic capsular release. We compared clinical outcomes and the overall duration of symptoms between 2 groups: Group I comprised 27 patients who underwent surgery <6 months after onset (mean, 3.8 months), whereas group II comprised 33 patients who underwent surgery ≥6 months after onset (mean, 11.1 months). The severity of glenohumeral synovitis at the time of surgery was evaluated. Patient-reported pain, shoulder function, and range of motion, as well as the presence of sleep disturbance, were assessed preoperatively and at 3 and 6 months after surgery. RESULTS: Both groups showed significant improvements in the visual analog scale pain score, Japanese Orthopaedic Association score, American Shoulder and Elbow Surgeons score, and prevalence of sleep disturbance after surgery (P < .001), although the glenohumeral synovitis score was significantly higher in group I than in group II (P < .0001). Forward flexion at 6 months after surgery was significantly greater in group I than in group II (P = .007). The overall duration of symptoms was shorter in group I than in group II (P < .0001). Neither the pain score, functional score, prevalence of sleep disturbance, nor postoperative recovery time differed between groups. CONCLUSIONS: Arthroscopic capsular release provided significant pain relief and improvement in shoulder function in patients with frozen shoulder regardless of the timing of surgery. Early surgical intervention might shorten the overall duration of symptoms in frozen shoulder and is not associated with inferior clinical outcomes when compared with late surgical intervention. Surgeons do not need to delay surgical intervention for patients who have intolerable pain and/or nocturnal pain with sleep disturbance.

Histologic changes during healing with autologous fascia lata graft after superior capsule reconstruction in rabbit model.

BACKGROUND: Superior capsule reconstruction (SCR) has been developed to improve shoulder function and relieve pain in the treatment of irreparable rotator cuff tears. Previous studies have reported that graft healing can enhance favorable outcomes after SCR. On the other hand, graft tears often lead to less desirable outcomes and sometimes require additional surgical procedures. However, the healing process underlying this remains unclear. In this study, we aimed to investigate histologic changes occurring during the healing process associated with autologous fascia lata graft after SCR in vivo. We hypothesized that (1) autologous fascia lata graft can regenerate the fibrocartilaginous insertion into both the greater tuberosity and superior glenoid and (2) the midsubstance of the grafted fascia gradually remodels into tendon- and/or ligament-like tissue after SCR. METHODS: Irreparable supraspinatus tendon defects were created in 24 mature Japanese white rabbits (age, 6 months; mean weight, 3.2 kg). Four weeks after creation of the defects, the right shoulders were subjected to SCR using autologous fascia lata grafts. The left shoulders were left untreated. Samples from the shoulders were harvested at 4, 8, 12, and 16 weeks after surgery to undergo histologic and immunohistochemical examinations. RESULTS: Macroscopically, we did not observe graft tears after SCR in our experiments. Histologically, the number of chondrocyte-like cells gradually increased, and the extracellular matrices around those cells contained glycosaminoglycan at the fascia-bone junction after SCR. The unmineralized fibrocartilage, mineralized fibrocartilage, and tidemark were observed 16 weeks after SCR. The distribution of type II collagen presented a pattern similar to that of a normal tendon and ligament insertion. The cells and collagen fiber gradually oriented parallelly to the long axis in the midsubstance of the grafted fascia lata. Additionally, type III collagen was replaced with type I collagen in the midsubstance of the grafted fascia lata after SCR. CONCLUSIONS: SCR using fascia lata autograft regenerated the fibrocartilaginous insertion at both the greater tuberosity and superior glenoid. The midsubstance of the grafted fascia gradually remodeled into tendon- and/or ligament-like tissue. These results suggest that the fascia lata autograft has the capacity for graft-to-bone healing and remodeling after SCR.

Relationship between humeral retroversion and baseball positions during elementary and junior-high school.

BACKGROUND: Humeral retroversion is greater in the dominant shoulder than in the nondominant shoulder in baseball players. However, the effect of different baseball positions during childhood on humeral retroversion remains unknown. The purpose of this study was to investigate the following: (1) the relationship between humeral retroversion and baseball positions played during elementary and junior-high schools; (2) the association between humeral retroversion and the prevalence of pain during the medical checkup and self-reported history of injuries in the dominant shoulder or elbow. METHODS: We enrolled 149 male high-school baseball players who started playing baseball in elementary school. The subjects were classified into 3 groups according to their baseball positions in elementary and junior-high schools. All participants completed questionnaires regarding their current and past positions, current incidence and history of injuries in their shoulder or elbow joints, and the age they started playing baseball. Shoulder range of motion, humeral retroversion on ultrasonographic-assisted measurement, and the association between humeral retroversion and shoulder and elbow pain were evaluated. RESULTS: Humeral retroversion was significantly greater in the dominant shoulder than in the nondominant shoulder in all groups (P < .001). In addition, humeral retroversion in the dominant shoulder was significantly greater in players who were pitchers in both elementary and junior-high schools than in those who were fielders during both periods (96.2° and 89.4°, respectively; P = .02). Humeral retroversion in the dominant shoulder was positively correlated (P = .005, r = 0.23) with the length of career as a pitcher during elementary and junior-high schools. Humeral retroversion was not correlated with the prevalence of pain during the medical checkup or self-reported history of injuries in the dominant shoulder or elbow (P values ranging from 0.09-0.99). CONCLUSION: These results suggest that playing baseball as a pitcher during elementary school and junior-high school affects the increase in humeral retroversion in the dominant shoulder. Increased humeral retroversion in the dominant shoulder by repetitive throwing motion is an adaptive change, rather than a pathologic change.

Arthroscopic superior capsule reconstruction with Teflon felt synthetic graft for irreparable massive rotator cuff tears: clinical and radiographic results at minimum 2-year follow-up.

BACKGROUND: Superior capsule reconstruction (SCR) was developed to improve shoulder function and relieve pain in patients with irreparable rotator cuff tears. Here, we investigated the clinical and radiographic outcomes and postoperative complications of SCR using a Teflon graft for reconstruction. METHODS: Thirty-five consecutive patients with irreparable rotator cuff tears underwent SCR with Teflon grafts. The American Shoulder and Elbow Surgeons score, active shoulder elevation, shoulder muscle strength, visual analog scale pain scores, acromiohumeral distance, and postoperative complications were investigated. Data obtained before and after surgery were compared by using a paired t-test, χ2 test, and 1-way analysis of variance, and data from 1-layer-graft SCR (15 patients; mean age, 75.1 years) and 3-layer-graft SCR (20 patients; mean age, 76.6 years) were compared by using an unpaired t-test. The average time to final follow-up was 42 months (range, 24-69 months). RESULTS: SCR using Teflon grafts of either 1 or 3 layers significantly improved the American Shoulder and Elbow Surgeons score (by 20.8, P = .001 for a 1-layer graft; and by 31.1, P < .0001 for a 3-layer graft), visual analog scale score for motion pain (by 3.2, P = .001; and by 3.0, P < .0001), and muscle strength in shoulder abduction (by 11.9 N, P = .02; and by 10.9 N, P = .008). Active elevation at final follow-up was significantly greater in the 3-layer-graft group (142° ± 27°) than in the 1-layer-graft group (107° ± 42°) (P = .006). One year after SCR, acromiohumeral distance in the 3-layer-graft group was significantly greater than preoperatively (P = .04), whereas in the 1-layer-graft group, it was not. On postoperative magnetic resonance imaging, none of the patients in the 3-layer-graft group had graft tears, whereas 2 patients had graft tears and 1 patient had severe synovitis after 1-layer-graft SCR. CONCLUSION: SCR using a Teflon graft-especially a 3-layer graft-significantly improved shoulder function and shoulder abduction strength, with pain relief and a low rate of postoperative complications. SCR using a Teflon graft can be a viable option for irreparable rotator cuff tears, especially when an autograft or allograft is not available.

Biomechanical assessment of docking ulnar collateral ligament reconstruction after failed ulnar collateral ligament repair with suture augmentation.

BACKGROUND: Ulnar collateral ligament (UCL) repair with single-strand suture augmentation has been introduced as a viable surgical option for throwers with acute UCL tears. For the original single-strand suture augmentation construct, revision UCL reconstructions can be challenging owing to the bone loss at the site of anchor insertion in the center of the sublime tubercle. This biomechanical study assessed a small-diameter (1.5-mm) ulnar bone tunnel technique for double-strand suture-augmented UCL repair that may be more easily converted to salvage UCL reconstruction if necessary, as well as a salvage UCL reconstruction with a docking technique after a failed primary suture-augmented UCL repair. METHODS: In 7 fresh-frozen cadaveric upper extremities (mean age, 66.3 years), a custom shoulder testing system was used to simulate the late cocking phase of throwing. The elbow valgus opening angle was evaluated using a MicroScribe 3DLX device for sequentially increasing valgus torque (from 0.75 to 7.5 Nm in 0.75-Nm increments) at 90° of flexion. Valgus angular stiffness (in newton-meters per degree) was defined as the correlation of sequentially increasing valgus torque with the valgus opening angle through simple linear regression (slope of valgus torque - valgus opening angle curve). Four conditions were tested: intact elbow, distal UCL avulsion, primary UCL repair with double-strand suture augmentation using small-diameter bone tunnels, and subsequent docking UCL reconstruction in the same specimen. Load-to-failure tests were performed for primary UCL repair with double-strand suture augmentation and subsequent docking UCL reconstruction. RESULTS: With increasing elbow valgus torque, the valgus opening angle increased linearly in each condition (R2 ≥ 0.98, P < .001). Distal UCL avulsion resulted in significantly decreased angular stiffness compared with the intact UCL (P < .001). Both UCL repair with double-strand suture augmentation and subsequent UCL reconstruction showed significantly increased angular stiffness values compared with distal UCL avulsion (P < .001 and P < .001, respectively). On load-to-failure testing, there was no significant difference in stiffness, yield torque, and ultimate torque between the primary suture-augmented UCL repair and the subsequent UCL reconstruction (P = .11, P = .77, and P = .38, respectively). In all specimens undergoing the small-diameter ulnar bone tunnel technique for double-strand suture-augmented UCL repair, failure occurred by retear of the repaired ligament without causing an ulnar bone bridge fracture. CONCLUSION: Primary UCL repair with double-strand suture augmentation using small-diameter bone tunnels was able to restore valgus stability. When failure occurs, this technique retains enough cortical bone to permit subsequent docking UCL reconstruction.

Posterior shoulder tightness can be a risk factor of scapular malposition: a cadaveric biomechanical study.

BACKGROUND: Scapular malposition and posterior shoulder tightness are key pathologic processes in the shoulder of throwing athletes. The objective of this study was to investigate the effects of posterior capsule tightness, posterior rotator cuff muscle tightness, or both on scapular position. METHODS: Ten shoulders from 5 fresh frozen cadaveric male torsos were tested in maximum internal, neutral, and maximum external shoulder rotations at 0°, 45°, and 90° of shoulder abduction. Scapular rotation-namely, upward and downward rotation, internal and external rotation, and anterior and posterior tilt-and the scapula-spine distance were measured by using a MicroScribe digitizer (Revware, Raleigh, NC, USA). Each shoulder underwent 4 experimental stages: intact; isolated posterior rotator cuff muscle (infraspinatus and teres minor) tightness; both posterior rotator cuff muscle and capsule tightness; and isolated posterior capsule tightness. RESULTS: Posterior muscle tightness significantly decreased upward rotation (P< .05) only in maximum shoulder internal rotation at 45° or 90° of shoulder abduction, whereas posterior capsule tightness did not affect upward rotation (P= .09 to .96). Posterior capsule tightness significantly increased scapular internal rotation (P< .01), but posterior muscle tightness did not change scapular internal rotation (P= .62 to .89). Posterior capsule tightness significantly increased both the superior and inferior scapula-spine distance (ie, caused scapular protraction) in maximum shoulder external rotation at 90° of abduction (P< .01). CONCLUSION: Posterior shoulder tightness resulted in scapular malposition. However, the muscular and capsular components of that tightness affected the scapular position differently. For the treatment of scapula malposition, stretching of the posterior shoulder capsule and muscles is recommended.

Editorial Commentary: Superior Capsule Reconstruction: Grafts for Superior Capsular Reconstruction Must Be Thick and Stiff.

To achieve a good functional outcome, including minimal graft tear, after superior capsule reconstruction, surgeons should carefully compare the biomechanical properties of all graft materials under consideration. In particular, graft stiffness affects postoperative stability in the glenohumeral joint, acromiohumeral distance, and graft healing. In my experience, a sufficiently stiff fascia lata graft is 6- to 8-mm thick and includes suture reinforcement and/or an augmentation patch. I believe that augmenting acellular dermal allografts in a similar way will decrease the incidence of graft elongation, persistent superior migration of the humoral head, and other complications after superior capsule reconstruction.

Editorial Commentary: Superior Capsular Reconstruction-Improved Superior Stability and Functional Deltoid Reverse Pseudoparalysis in Patients With Irreparable Rotator Cuff Tears.

Since I reported clinical and biomechanical improvement after superior capsular reconstruction (SCR) for irreparable rotator cuff tears in 2012 and 2013, many shoulder surgeons around the world have started to perform SCR. However, most of these surgeons are still on the learning curve, and their clinical results are not consistent because clinical outcomes after SCR are correlated with graft healing, which is affected by the surgeon's skill. In cases in which the graft does heal, active shoulder elevation increases after SCR even in patients with pseudoparalysis before surgery. These patients can elevate the arm using the deltoid muscle when superior shoulder stability is restored after SCR. When patients whose grafts have healed cannot elevate the arm even after SCR, they may have concomitant cervical radiculopathy, which causes real paralysis.

Ulnar collateral ligament insufficiency affects cubital tunnel syndrome during throwing motion: a cadaveric biomechanical study.

BACKGROUND: In throwing athletes, cubital tunnel syndrome and insufficiency of the ulnar collateral ligament (UCL) are common pathologic processes of the elbow. The objective of this study was to investigate the effect of UCL tears on ulnar nerve elongation in the simulated throwing position. METHODS: Eight fresh frozen cadaveric upper limbs were tested at the simulated late cocking to acceleration phase in the throwing motion using an elbow testing system. Elbow valgus laxity and ulnar nerve length and strain under 2 Nm of applied valgus torque (maximum torque in cadaveric elbow) were evaluated. Paired t-tests were used to compare all data between intact UCLs and UCLs after complete transection of the anterior oblique ligament. Linear regression analysis was used to investigate relationships between elbow valgus laxity and ulnar nerve strain. RESULTS: Elbow valgus laxity significantly increased after transection of the UCL. Ulnar nerve length after UCL transection was significantly greater than that in the intact condition at 60° (P = .006) and 90° of elbow flexion (P < .0001). In addition, ulnar nerve strain was positive (increased) at 60° and 90° of elbow flexion. Maximum ulnar nerve strain at 90° of elbow flexion was 3.9% ± 0.9% when the UCL was intact and 6.8% ± 0.7% after transection. UCL transection yielded significant positive correlation between elbow valgus laxity and ulnar nerve strain (P = .006; r = .4714). CONCLUSION: Increased elbow valgus laxity due to UCL insufficiency may cause elongation of the ulnar nerve and exacerbate cubital tunnel syndrome during the throwing motion.

Editorial Commentary: Superior Capsule Reconstruction: Graft Healing for Success.

In my experience, after superior capsule reconstruction for irreparable rotator cuff tears, if the graft heals, we can expect a successful outcome, such as an American Shoulder and Elbow Surgeons score of more than 90 points and a visual analog scale score of less than 1.0. To decrease the graft tear rate after surgery, I have found that a thicker, stiffer graft than can be achieved with a dermal allograft alone is required to restore superior stability in the glenohumeral joint. Furthermore, the graft size should be determined precisely from the size of the defect in the rotator cuff tendons.

Lower shoulder abduction during throwing motion may cause forceful internal impingement and decreased anterior stability.

BACKGROUND: Internal impingement and decreased anterior stability, which result from shoulder capsular loosening, are common shoulder pathologies in throwing athletes. The purpose of this study was to assess the effect of shoulder abduction angle on shoulder internal impingement and anterior shoulder stability during the simulated throwing motion. METHODS: Eight cadaveric shoulders were tested by simulating the late-cocking and acceleration phases of the throwing motion for intact and thrower's shoulder conditions. The maximal glenohumeral external rotation, anterior translation, location of the rotator cuff insertion with respect to the glenoid, length and site of internal impingement, and glenohumeral contact pressure were measured. All data were compared between shoulder abduction angles of 80°, 90°, and 100°. RESULTS: Decreasing shoulder abduction in the simulated late-cocking phase shifted the humeral head posteriorly (P < .03) and superiorly (P < .001), decreasing the total internal impingement area between the greater tuberosity and glenoid (P = .04) and increasing the glenohumeral contact pressure during internal impingement (P = .02). In the simulated acceleration phase, anterior glenohumeral translation significantly increased as the shoulder abduction angle decreased (P < .001). CONCLUSION: Decreasing shoulder abduction significantly increased the contact pressure during internal impingement in the simulated late-cocking phase of the throwing motion. During the simulated acceleration phase of the throwing motion, anterior glenohumeral translation significantly increased as shoulder abduction decreased.

A biomechanical cadaveric study comparing superior capsule reconstruction using fascia lata allograft with human dermal allograft for irreparable rotator cuff tear.

BACKGROUND: Biomechanical and clinical success of the superior capsule reconstruction (SCR) using fascia lata (FL) grafts has been reported. In the United States, human dermal (HD) allograft has been used successfully for SCRs; however, the biomechanical characteristics have not been reported. METHODS: Eight cadaveric shoulders were tested in 5 conditions: (1) intact; (2) irreparable supraspinatus tear; (3) SCR using FL allograft with anterior and posterior suturing; (4) SCR using HD allograft with anterior and posterior suturing; and (5) SCR using HD allograft with posterior suturing. Rotational range of motion, superior translation, glenohumeral joint force, and subacromial contact were measured at 0°, 30°, and 60° of glenohumeral abduction in the scapular plane. Graft dimensions before and after testing were also recorded. Biomechanical parameters were compared using a repeated-measures analysis of variance with Tukey post hoc test, and graft dimensions were compared using a Student t-test (P < .05). RESULTS: Irreparable supraspinatus tear significantly increased superior translation, superior glenohumeral joint force, and subacromial contact pressure, which were completely restored with the SCR FL allografts. Both SCR HD allograft repairs partially restored superior translation and completely restored subacromial contact and superior glenohumeral joint force. The HD allografts significantly elongated by 15% during testing, whereas the FL allograft lengths were unchanged. CONCLUSIONS: Single-layered HD SCR allografts partially restored superior glenohumeral stability, whereas FL allograft SCR completely restored the superior glenohumeral stability. This may be due to the greater flexibility of the HD allograft, and the SCR procedure used was developed on the basis of FL grafts.

Bridging suture makes consistent and secure fixation in double-row rotator cuff repair.

BACKGROUND: Inconsistent tension distribution may decrease the biomechanical properties of the rotator cuff tendon after double-row repair, resulting in repair failure. The purpose of this study was to compare the tension distribution along the repaired rotator cuff tendon among three double-row repair techniques. METHODS: In each of 42 fresh-frozen porcine shoulders, a simulated infraspinatus tendon tear was repaired by using 1 of 3 double-row techniques: (1) conventional double-row repair (no bridging suture); (2) transosseous-equivalent repair (bridging suture alone); and (3) compression double-row repair (which combined conventional double-row and bridging sutures). Each specimen underwent cyclic testing at a simulated shoulder abduction angle of 0° or 40° on a material-testing machine. Gap formation and tendon strain were measured during the 1st and 30th cycles. To evaluate tension distribution after cuff repair, difference in gap and tendon strain between the superior and inferior fixations was compared among three double-row techniques. RESULTS: At an abduction angle of 0°, gap formation after either transosseous-equivalent or compression double-row repair was significantly less than that after conventional double-row repair (p < 0.01). During the 30th cycle, both transosseous-equivalent repair (p = 0.02) and compression double-row repair (p = 0.01) at 0° abduction had significantly less difference in gap formation between the superior and inferior fixations than did conventional double-row repair. After the 30th cycle, the difference in longitudinal strain between the superior and inferior fixations at 0° abduction was significantly less with compression double-row repair (2.7% ± 2.4%) than with conventional double-row repair (8.6% ± 5.5%, p = 0.03). CONCLUSIONS: Bridging sutures facilitate consistent and secure fixation in double-row rotator cuff repairs, suggesting that bridging sutures may be beneficial for distributing tension equally among all sutures during double-row repair of rotator cuff tears.

Intra- and Inter-rater Agreement on Magnetic Resonance Imaging Evaluation of Rotator Cuff Integrity After Repair.

PURPOSE: To investigate the intra- and inter-rater agreement of magnetic resonance imaging (MRI) evaluations of rotator cuff integrity at 6 and 24 months after arthroscopic rotator cuff repair (ARCR). METHODS: Three shoulder surgeons reviewed 68 MRI scans from 34 patients who had undergone ARCR and MRI examination at both 6 and 24 months after surgery. Postoperative rotator cuff integrity was investigated by using Owen, Sugaya, and Hayashida classifications to determine whether the rotator cuff was intact or whether there was a partial-thickness retear or full-thickness retear and Burks score to assess tendon appearance. Multirater kappa statistics were used to measure intra- and inter-rater agreement. Kappa values were interpreted according to guidelines adapted from the work of Landis and Koch. RESULTS: All classifications had similar intra- and inter-rater agreement (κ = 0.14 to 0.67, 0.23 to 0.60, respectively), but no intra- or inter-rater agreement scored "excellent." Inter-rater agreement after ARCR was higher at 24 months (κ = 0.31 to 0.60) than at 6 months (κ = 0.23 to 0.44) in all evaluations. Reviewers identified full-thickness retears with a moderate to good degree of inter-rater agreement in all evaluations, at both 6 months (κ = 0.42 to 0.73) and 24 months (κ = 0.61 to 0.80) after ARCR. However, poor inter-rater agreement (κ = 0.13 to 0.19) was found in the identification of partial-thickness retears in all evaluations at 6 months after ARCR. CONCLUSIONS: Shoulder surgeons showed better intra- and inter-rater agreement in predicting full-thickness tears compared with partial-thickness tears. The inter-rater agreement at 24 months after ARCR was superior to that at 6 months in predicting not only full-thickness retear but also partial-thickness retear. MRI evaluation of rotator cuff integrity at 6 months after ARCR may be less reliable, regardless of which classification system is used. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Biomechanical Effect of Thickness and Tension of Fascia Lata Graft on Glenohumeral Stability for Superior Capsule Reconstruction in Irreparable Supraspinatus Tears.

PURPOSE: To investigate the effects of graft length and thickness on shoulder biomechanics after superior capsule reconstruction. METHODS: Subacromial peak contact pressure and glenohumeral superior translation were measured at 0°, 30°, and 60° of glenohumeral abduction in 8 fresh-frozen cadaveric shoulders under 5 conditions: (1) intact shoulder; (2) irreparable supraspinatus tendon tear, (3) superior capsule reconstruction with a fascia lata allograft 4-mm thick and 15 mm longer than the distance from the superior glenoid to the lateral edge of the greater tuberosity, as determined during placement at 30° of glenohumeral abduction; (4) superior capsule reconstruction with a fascia lata allograft 8-mm thick and with the same 15 mm relative length determined at 10° of glenohumeral abduction, and (5) superior capsule reconstruction with a fascia lata allograft 8-mm thick and with the 15-mm relative length determined at 30° of glenohumeral abduction. To investigate the effect of graft thickness, we compared the data from conditions 1, 2, 3, and 5. To assess the effect of graft length, we compared conditions 1, 2, 4, and 5. RESULTS: With superior capsule reconstruction using a 4-mm graft, subacromial peak contact pressure (but not superior translation) was significantly lower than with irreparable supraspinatus tears (at 0° abduction: 259% decrease; P = .0002; at 30° abduction: 113% decrease; P = .01). The superior capsule reconstruction using an 8-mm graft significantly decreased both subacromial peak contact pressure (at 0° abduction: 246% decrease, P = .0002; at 30° abduction: 158% decrease; P = .0008; at 60° abduction: 57% decrease; P = .04) and superior translation (at 0° abduction: 135% decrease; P = .02; at 30° abduction; 130% decrease; P = .004). Graft length with placement at 10° glenohumeral abduction was 5 mm greater than that at 30° abduction. The 8-mm superior capsule reconstruction performed at 10° or 30° of glenohumeral abduction significantly decreased subacromial peak contact pressure (placement at 10° and 30°: 0° abduction, P = .0002 and .0002, respectively; 30° abduction, P = .0004 and .0005, respectively; 60° abduction, P = .04 and .04, respectively) and superior translation (placement at 10° and 30°; 0° abduction, P =.04 and .02, respectively; 30° abduction, P = .02 and .004, respectively) compared with irreparable supraspinatus tears. CONCLUSIONS: Superior capsule reconstruction normalized the superior stability of the shoulder joint when the graft was attached at 10° or 30° of glenohumeral abduction. An 8-mm-thick graft of fascia lata had greater stability than did a 4-mm-thick graft. CLINICAL RELEVANCE: Grafts 8-mm thick and attached at 15° to 45° of shoulder abduction (equal to 10° to 30° of glenohumeral abduction) biomechanically restore shoulder stability during superior capsule reconstruction using fascia lata.