Elasticity assessment of flexor pronator muscles using shear wave elastography.

Background: The flexor pronator muscles (FPMs) have been thought as a dynamic stabilizer to protect the ulnar collateral ligament (UCL) from valgus stress during throwing motion. Thus, evaluation of the FPMs is important for preventing UCL injuries. Shear wave ultrasound elastography (SWE) is an imaging modality that quantifies tissue elasticity. The purpose of this study was to measure the tissue elasticities of healthy FPMs using SWE. Methods: We investigated 22 healthy men (mean age, 29 ± 6 years). The elasticities of the FPMs, including the pronator teres (PT), flexor digitorum superficialis (FDS), and flexor carpi ulnaris (FCU), were measured using SWE for each arm under two conditions: at rest (unloaded) and under valgus stress (loaded). The values obtained under different loading conditions were compared between both elbows. Results: The mean SWE values of the PT, FDS, and FCU for the dominant elbows were 22.4 ± 3.6, 22.8 ± 2.9, and 22.3 ± 3.4 kPa, respectively. The corresponding mean SWE values for the nondominant elbows were 24.2 ± 4.6, 23.1 ± 3.5, and 23.4 ± 3.5 kPa, respectively. The mean SWE values of the PT, FDS, and FCU at rest (unloaded) were 23.3 ± 4.2, 22.9 ± 3.2, and 22.9 ± 3.5 kPa, respectively. The corresponding mean SWE values under valgus stress (loaded) were 35.0 ± 6.2, 34.7 ± 5.3, and 31.9 ± 4.8 kPa, respectively. Conclusion: This noninvasive evaluation of the stiffness of the FPMs may provide clinically relevant data for the prevention of UCL injuries.

Stiffness Changes in Shoulder Muscles between Pitchers and Position Players after Throwing Overhead Using Shear Wave Elastography and Throwing Motion Analysis.

Objectives: The objective is to compare stiffness changes around the shoulder muscles between pitchers and position players after throwing overhead using shear wave elastography (SWE) in relation to throwing motion analysis and muscle strength. Methods: A total of 32 male college baseball players (12 pitchers and 20 position players) were observed throwing 20 times, and SWE was performed to evaluate 13 shoulder muscle items-tendons (supraspinatus, infraspinatus, subscapularis, and teres minor), muscles (supraspinatus, infraspinatus [transverse and oblique part], teres minor, lower trapezius, latissimus dorsi, and pectoralis minor), and capsules (posterior and posteroinferior). Motion analysis was used to assess elbow torque, forearm angle, forearm rotation speed, and maximum external rotation angle of the shoulder. Muscle strength was measured using a dynamometer for abduction, internal/external rotation of the shoulder at an abduction of 0°, internal/external rotation of the shoulder at an abduction of 90°, and internal/external rotation of shoulder at a flexion of 90°. Results: In the pitcher group, SWE values for the teres minor muscle and latissimus dorsi muscle increased significantly after throwing. In the position player group, SWE values for the teres minor muscle significantly increased, and SWE values of the pectoralis minor muscle decreased after throwing. In the pitcher group, positive correlations were found between the teres minor muscle and forearm rotation speed and between the latissimus dorsi muscle and forearm angle. No significant difference was found in muscle strength after throwing in any of the groups. Conclusions: Stiffness changes occurred after throwing and were related to the motion analysis, but the regions in which stiffness occurred varied between pitchers and position players.

Arthroscopically Assisted Coracoclavicular (CC) Stabilization Using a Suture Button Device for Lateral Clavicle Fractures with CC Ligament Injury.

Background: Lateral clavicle fractures represent approximately 10-15% of all clavicle fractures. However, controversy exists regarding the optimal surgical treatment because of instability associated with the coracoclavicular (CC) ligament injury and a small lateral fragment. The purpose of this study was to evaluate the radiological and clinical outcomes of arthroscopically assisted CC stabilization using a suture button device for lateral clavicle fractures accompanied by CC ligament injury. Methods: A retrospective observational study involved six patients with modified Neer type IIB fractures, which were treated with the technique and followed for 12 months. Postoperative range of motion (ROM) and X-rays were evaluated every 3 months. Shoulder functional scores (University of California Los Angeles score, Japanese Orthopedics Association score) and visual analog scale (VAS) scores for pain (at rest, at night, and during motion) and for satisfaction were analyzed 12 months after surgery. Results: Early phase ROM recovery and excellent outcomes were achieved. All patients achieved bone union. Slight superior clavicle displacement and bone hole dilation occurred with no critical complications. Conclusions: Arthroscopically assisted CC stabilization with a suture button device for unstable lateral clavicle fractures can produce satisfactory radiological and clinical results.

The Combined Suture Bridge With Mason-Allen Technique Is Superior to the Conventional Suture Bridge Technique for Arthroscopic Rotator Cuff Repair.

PURPOSE: To compare clinical results and retear rates between the combined suture bridge with Mason-Allen (SBMA) technique and the conventional suture bridge (SB) technique in patients with full-thickness rotator cuff tears who underwent arthroscopic rotator cuff repair. METHODS: One hundred two patients who underwent arthroscopic rotator cuff repair using the SB technique (n = 50) or SBMA technique (n = 52) for a full-thickness rotator cuff tear and had at least 2 years of follow-up were retrospectively analyzed. Magnetic resonance imaging was performed before surgery and 2 years after to determine preoperative tear size, Goutallier stage, and presence of retear after surgery. Patients were clinically evaluated using the Japanese Orthopaedic Association (JOA) score. RESULTS: The groups did not significantly differ in terms of follow-up period, age, sex, tear size, Goutallier stage, or number of suture anchors. The retear rate was significantly lower in the SBMA group (7.7% vs 28.0%; P < .01). The JOA score was significantly higher at last follow-up than before surgery in both groups (P <.01). The JOA score at last follow-up was significantly higher in the SBMA group (P = .02). CONCLUSIONS: Arthroscopic rotator cuff repair using the SBMA technique may provide better clinical and anatomical outcomes than the conventional SB technique. LEVEL OF EVIDENCE: Level III, retrospective cohort design; treatment study).

Shear wave elastography correlates to degeneration and stiffness of the long head of the biceps tendon in patients undergoing tenodesis with arthroscopic shoulder surgery.

BACKGROUND: Tendinopathy of the long head of the biceps (LHB) tendon causes degeneration and changes its stiffness. However, a reliable means of diagnosis has not been established. Shear wave elastography (SWE) provides quantitative tissue elasticity measurements. In this study, the relationship of preoperative SWE values with biomechanically measured stiffness and degeneration of the LHB tendon tissue was investigated. METHODS: LHB tendons were obtained from 18 patients who underwent arthroscopic tenodesis. SWE values were measured preoperatively at 2 sites, proximal to and within the bicipital groove of the LHB tendon. The LHB tendons were detached immediately proximal to the fixed sites and at their superior labrum insertion. Tissue degeneration was histologically quantified using the modified Bonar score. Tendon stiffness was determined using a tensile testing machine. RESULTS: The SWE values of the LHB tendon were 502.1 ± 113.6 kPa proximal to the groove and 439.4 ± 123.3 kPa within the groove. The stiffness was 39.3 ± 19.2 N/mm. The SWE values displayed a moderate positive correlation with the stiffness proximal to the groove (r = 0.80) and within it (r = 0.72). The SWE value of the LHB tendon within the groove showed a moderate negative correlation with the modified Bonar score (r = -0.74). CONCLUSIONS: These findings suggest that preoperative SWE values of the LHB tendon correlate moderately positively with stiffness and moderately negatively with tissue degeneration. Therefore, SWE may predict LHB tendon tissue degeneration and changes in stiffness caused by tendinopathy.

The Effect of Vitamin C and N-Acetylcysteine on Tendon-to-Bone Healing in a Rodent Model of Rotator Cuff Repair.

BACKGROUND: Oxidative stress inhibits tendon-to-bone healing after rotator cuff repair. Regulation of oxidative stress has the potential to accelerate this healing, but its mechanism remains unclear. PURPOSE: To investigate the effects of reducing oxidative stress by applying antioxidants, such as N-acetylcysteine (NAC) and vitamin C (VC), on rotator cuff repair in a rat rotator cuff repair model. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 48 Sprague Dawley rats underwent bilateral surgery to repair the infraspinatus tendon to its insertion site 1 week after detachment. Rats were assigned to either the NAC group, the VC group, or a control group. Histological evaluation was performed via hematoxylin-eosin or toluidine blue staining, and oxidative stress was assessed via dihydroethidium intensity and protein carbonyl concentration at 3 and 6 weeks. Superoxide dismutase 1 (SOD1), SOD2, SOD3, peroxiredoxin 5, collagen type I (COL1), COL3, matrix metalloproteinase 1 (MMP-1), MMP-3, and MMP-13 expression and SOD activity were determined at 3 and 6 weeks. Biomechanical tests were performed at 6 and 12 weeks. RESULTS: Histological evaluation showed that the number of chondrocytes in the NAC group at 6 weeks and in the VC group at 3 and 6 weeks, the area of fibrocartilage at 6 weeks in the VC group, and collagen fibers at 6 weeks in the NAC and VC groups were significantly increased compared with those in the control group. Dihydroethidium intensity at 3 and 6 weeks and protein carbonyls at 6 weeks in the NAC and VC groups were significantly decreased. SOD1 expression and SOD activity at 3 weeks in the VC group and peroxiredoxin 5 expression at 6 weeks in the NAC group were significantly upregulated compared with that in the control group. COL3 expression was significantly upregulated at 6 weeks in the VC group, and MMP-13 expression was significantly decreased at 6 weeks in the NAC and VC groups. The biomechanical strength showed no significant difference. CONCLUSION: Antioxidant treatment, via NAC or VC administration, reduced oxidative stress in the rotator cuff repair site and accelerated healing. CLINICAL RELEVANCE: These findings provide essential indications to develop clinical strategies for improved healing after rotator cuff surgical repair in patients.

Chronologic Changes in the Elastic Modulus of a Healing Achilles Tendon Rupture Measured Using Shear Wave Elastography.

BACKGROUND: Shear wave elastography (SWE) has been used to examine the elasticity of a ruptured Achilles tendon; however, the healing process of a ruptured tendon has not been studied yet. This study aimed to detail the change in mechanical properties of a healing Achilles tendon rupture managed conservatively or surgically using SWE. METHODS: Using a prospective cohort study design, we evaluated the patients treated conservatively (conservative group) and surgically (surgical group) with the "gift-box" technique for an isolated index acute Achilles tendon rupture during their healing process. SWE measurements were taken of both the injured and uninjured sides every 4 weeks up to 24, 36, and 48 weeks after treatment. Additionally, tendon thickness and power Doppler (PD) grade were measured at the same time points as SWE measurements. The American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot rating system score and Achilles tendon Total Rupture Score (ATRS) were compared at 24 and 48 weeks. RESULTS: The ruptured Achilles tendon obtained an SWE value comparable with the unruptured side at 12 weeks in the conservative group and at 4 weeks with surgical group. The surgical group had significantly higher SWE values up to 24 weeks compared with the conservative group. Additionally, this group had a significantly larger increase in tendon thickness in nearly all periods. Both treatment groups were comparable regarding the PD grade, AOFAS score, and ATRS. CONCLUSION: SWE is a convenient noninvasive method to determine the progress of the healing process after tendon injury. Our analysis using SWE has revealed the detailed chronologic changes in SWE values and related mechanical properties of a healing Achilles tendon rupture, which can be used for devising appropriate rehabilitation protocols. LEVEL OF EVIDENCE: Level II, prospective cohort study.

Posterior shoulder stiffness was associated with shoulder pain during throwing in college baseball players: assessment of shear wave elastography.

PURPOSE: To investigate shoulder stiffness on the throwing and non-throwing sides in college baseball players using ultrasound shear wave elastography (SWE), and investigate the relationship between stiffness and shoulder pain during throwing. METHODS: Forty-nine college baseball players (98 shoulders) were recruited. Shoulder range of motion was evaluated. SWE was used to measure stiffness of the bilateral supraspinatus tendons, infraspinatus tendons, subscapularis tendons, supraspinatus muscles, infraspinatus muscles (ISPM), and posterior capsules. Participants were divided into pain and no pain groups based on the presence or absence of shoulder pain during throwing within 1 month before measurements on the throwing side. Items were compared between the throwing and non-throwing sides, and between the pain and no pain groups. Factors affecting shoulder pain during throwing were also investigated via multiple logistic regression analysis. RESULTS: Compared with the non-throwing side, the throwing side had significantly greater external rotation at 90° abduction, significantly lesser internal rotation at 0° abduction and internal rotation at 90° abduction (AbdIR), significantly higher SWE values of the infraspinatus tendon, ISPM, and posterior capsule, and significantly lower SWE values of the subscapularis tendon. Compared with the no pain group, the pain group had a significantly higher SWE value of the ISPM, and significantly lesser AbdIR. Increased ISPM SWE values and decreased AbdIR were significantly correlated with shoulder pain during throwing. CONCLUSIONS: The posterior tissue was stiffer than the anterior tissue on the throwing side. Decreased AbdIR and increased ISPM stiffness may be correlated with shoulder pain during throwing.

Arthroscopic Bankart repair with additional footprint fixation using the double-row technique at the 4 o'clock position anatomically restored the capsulolabral complex and showed good clinical results.

PURPOSE: To investigate the clinical outcome and magnetic resonance imaging (MRI) findings after arthroscopic Bankart repair with additional double anchor footprint fixation (DAFF) at the 4 o'clock position, where the native footprint is widest anatomically, for recurrent anterior shoulder instability. METHODS: Forty-two patients (mean age 27.0 years) with recurrent anterior shoulder instability and without severe glenoid bone defects underwent arthroscopic Bankart repair with additional DAFF at the 4 o'clock position. Using three standard portals, single-row repair was performed at the 2, 3, and 5 o'clock positions, and DAFF with the suture bridging technique was conducted at the 4 o'clock position. MRI was performed preoperatively and at 6 months postoperatively. Patients with follow-up periods of ≥1 year were included in the present study and clinically evaluated at the final follow-up. The morphology at the 2 and 4 o'clock positions on radial MRI slices was compared between the preoperative and 6-month postoperative scans, and the footprint of the repaired capsulolabral complex at 6 months postoperatively was compared between the 2 and 4 o'clock positions. RESULTS: The average follow-up period was 19.5 ± 6.2 months. The rates of dislocation recurrence and positive apprehension test results were 2.4 and 4.8%, respectively. External rotation was restricted by 3.5°. The University of California at Los Angeles and Rowe scores at the final follow-up were 34.5 ± 1.0 points and 97.2 ± 5.7 points, respectively, representing significant improvements over the preoperative scores (p < 0.01). Although the capsulolabral complex at 6 months postoperatively was firmly repaired at both the 2 and 4 o'clock positions compared to its preoperative state, the footprint of the restored capsulolabral complex was wider at the 4 o'clock position than at the 2 o'clock position (p < 0.01). CONCLUSIONS: Additional DAFF at the 4 o'clock position improved the glenohumeral stability and function of the shoulder joint. This study suggests that this technique is a reliable and useful treatment for shoulder instability. LEVEL OF EVIDENCE: IV.

Anatomical position of the corona mortis relative to the anteroposterior and inlet views.

PURPOSE: Although pubic ramus fractures are common in the elderly, resultant hemodynamic instability is a rare complication. The corona mortis, a vascular anastomosis between the obturator vessels and the external iliac vessels in the retropubic space, is occasionally damaged by fractures of the pubic ramus, causing significant hemorrhage. The purpose of this study was to evaluate the incidence and anatomical position of the corona mortis on the anteroposterior and inlet views. METHODS: Sixty-one cadavers (122 hemipelvizes) were dissected and the incidence of the corona mortis was evaluated. Photographs were then taken simulating anteroposterior and inlet radiographs, and labeled as the anteroposterior and inlet views. The distance from the pubic symphysis to the corona mortis was measured on each of the two views. RESULTS: The corona mortis was present in 76.1% of hemipelvizes. The corona mortis traverses along the periosteum of the dorsal surface of the pubis. The incidence of arterial corona mortis was 28.3% and that of venous corona mortis was 76.1%. The distance from the superior margin of the symphysis pubis to the corona mortis measured 47.7 ± 9.9 (45.9-49.6) mm on the anteroposterior view, and 59.4 ± 9.2 (57.3-61.5) mm on the inlet view. CONCLUSIONS: In order to predict possible hemodynamic instability of the corona mortis following pubic ramus fractures, it is of clinical significance to precisely establish the anatomical position of the corona mortis on the anteroposterior and inlet views.

Long-term effect of immobilization in external rotation after first-time shoulder dislocation: an average 18-year follow-up.

BACKGROUND: Immobilization in external rotation (ER) after a first-time shoulder dislocation was introduced to reduce the risk of recurrence compared with immobilization in internal rotation (IR), but its efficacy remains controversial. The purpose of this study was to determine the long-term effect of immobilization in ER after a first-time shoulder dislocation. METHODS: Between October 2000 and March 2004, 198 patients with a first-time anterior dislocation of the shoulder (average age 37) were randomly assigned to immobilization in ER (ER group = 104 shoulders) or IR (IR group = 94 shoulders) for 3 weeks. At an average 2-year follow-up, 159 patients (80.3%) were available for evaluation. In the current study, these 159 patients were further followed up and interviewed by telephone. The following items were evaluated: recurrent instability, apprehensive feeling, surgical intervention, limitation in the range of motion, return to sports, and the Single Assessment Numeric Evaluation (SANE) score. RESULTS: The average follow-up period was 18.2 years (range, 16-20 years). Fifty-six patients were available for follow-up with the follow-up rate of 35%. The number of recurrent patients was 6 of 27 (22%) in the ER group and 6 of 29 (21%) in the IR group (P = .889). The number of surgically stabilized patients was 3 of 27 (11%) in the ER group and 10 of 29 (34%) in the IR group (P = .038). In total, the recurrence rate was 33% (9 of 27) in the ER group and 55% (16 of 29) in the IR group (P = .100). Adding the surgical cases and those with the SANE score ≤70% as failure cases, the failure rate in the ER group (26%) was significantly lower than that in the IR group (52%) (P = .048). Among those who survived without surgical intervention, there were no significant differences in apprehensive feeling, return to sports, limited range of motion, and the SANE score between the groups. CONCLUSIONS: Immobilization in ER reduced the risk of surgical intervention compared with IR in the long term.

Relationship of superoxide dismutase to rotator cuff injury/tear in a rat model.

Rotator cuff degeneration is one of the several factors that lead to rotator cuff tears. Oxidative stress and superoxide dismutase have been reported to be related to rotator cuff degeneration; however, the precise mechanism still remains unclear. In this study, we investigated the relationship of oxidative stress and superoxide dismutase to the degeneration of the rotator cuff using rat models. Eighty-four rats were used to create a collagenase-induced rotator cuff injury model (injury model) and a rotator cuff tear model (tear model). The controls were administered saline and had only a deltoid incision, respectively. We evaluated degeneration morphology of the rotator cuff using a degeneration score; dihydroethidium fluorescence intensity, which detects oxidative stress; gene expression; and superoxide dismutase activity. The rotator cuffs in the injury and tear models significantly increased degeneration scores and dihydroethidium fluorescence intensity. On the other hand, gene expression of superoxide dismutase isoform, superoxide dismutase 1, and superoxide dismutase activity were significantly decreased in the injury model but showed no significant difference in the tear model. These findings suggested that superoxide dismutase might not be associated with rotator cuff degeneration after tear but may be involved in degenerative rotator cuff without tear. However, we found that rotator cuff degeneration involves oxidative stress both with and without tear. Based on these findings, it is presumed that different treatments may be appropriate, depending on the state of rotator cuff degeneration, because the mechanisms of the degeneration may be different.

Glenoid Bone Loss Is a Risk Factor for Poor Clinical Results After Coracoid Transfer in Rugby Players With Shoulder Dislocations.

BACKGROUND: Although surgical shoulder stabilization via coracoid transfer in collision athletes is effective and has a low reinjury rate, the factors affecting poor clinical results and the superiority of the 2 stabilization procedures (Bristow and Latarjet) remain unclear. PURPOSE: To explore the factor(s) affecting poor clinical results of coracoid transfer in a large cohort of rugby players and to compare postoperative function between the Bristow and Latarjet procedures. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This study included 169 consecutive shoulders of 154 competitive male rugby players who underwent shoulder stabilization surgery (Bankart repair with coracoid transfer) between 2014 and 2018 and had a mean follow-up of 2.7 years (minimum follow-up, 2 years). The Bristow procedure was performed in the first 92 shoulders (84 players), and the Latarjet procedure was performed in the latter 77 shoulders (70 players). A poor clinical result was defined as a postoperative Rowe score of <70 and a postoperative Western Ontario Shoulder Instability Index (WOSI) score of >630. Multiple logistic regression analysis was conducted to identify the factors affecting postoperative functional failure. The postoperative scores and complication rates were also compared between the 2 procedures. RESULTS: In total, 92.3% of the rugby players returned to their preinjury competition level at a mean of 5.9 months postoperatively. The Rowe and WOSI scores showed that shoulder function was improved postoperatively compared with preoperatively. The number of rugby players with a poor clinical result was 18 (10.7%). Multiple logistic regression analysis demonstrated that a poor clinical result was associated with a preoperative glenoid bone defect of >20% of the glenoid width (odds ratio, 9.8), whereas the clinical result was unaffected by the type of coracoid transfer. There were no differences between the 2 procedures in any of the postoperative scores or complication rates. CONCLUSION: The present study indicated that the most effective predictor of postoperative functional scores was the degree of the glenoid bone defect and not the type of coracoid transfer. This information may be useful for the strategic treatment of shoulder dislocations in collision athletes.

Association of Recurrent Tear After Arthroscopic Rotator Cuff Repair and Superoxide-Induced Oxidative Stress.

BACKGROUND: Recurrent tears after arthroscopic rotator cuff repair (ARCR) remain a significant clinical problem. Oxidative stress contributes to the degeneration of the rotator cuff, and a degenerative rotator cuff can lead to recurrent tear after ARCR. However, the correlation between oxidative stress and retear after ARCR is unclear. PURPOSE: To investigate the correlation between superoxide-induced oxidative stress and recurrent tear after ARCR. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 68 patients who underwent ARCR using a suture-bridge technique participated in this study. Specimens were collected from the edge of the torn tendon during surgery. The modified Bonar score was used to evaluate degeneration of the rotator cuff on histological specimens, and fluorescence intensity on dihydroethidium (DHE) staining was used to detect oxidative stress. Superoxide dismutase (SOD) enzyme activity was also measured. The following were used for clinical evaluation: age, tear size on magnetic resonance imaging (MRI) before surgery, Goutallier classification on MRI before surgery, and Japanese Orthopaedic Association score before and 6 months after surgery. After the repaired rotator cuffs were evaluated on MRI 6 months after surgery, the patients were divided into groups: those with a healed rotator cuff (healed group; n = 46) and those with a recurrent tear (retear group; n = 22). The significant differences between the groups were determined with regard to clinical evaluation, modified Bonar score, DHE intensity, and SOD activity. In addition, multivariate logistic regression analysis was performed to investigate risk factors for recurrent tear. RESULTS: Age, tear size, Goutallier classification, modified Bonar score, DHE intensity, and SOD activity were significantly greater in the retear group than in the healed group, although the Japanese Orthopaedic Association score was not significantly different. Multiple logistic regression analysis demonstrated that age, tear size, and SOD activity were significantly correlated with recurrent tear. CONCLUSION: In addition to tear size and age, superoxide-induced oxidative stress may be an exacerbating factor for retear after ARCR.

Stiffness change of the supraspinatus muscle can be detected by magnetic resonance elastography.

Magnetic resonance elastography (MRE) and ultrasound shear wave elastography (SWE) are imaging techniques to measure stiffness of the soft tissue using magnetic resonance imaging (MRI) and ultrasound images, respectively. The purpose of this study was to explore the feasibility of the MRE measurement to evaluate the change in supraspinatus (SSP) muscle stiffness before and after rotator cuff tear, and to compare the result with those of SWE. Six swine shoulders were used. The skin and subcutaneous fat were removed, and the stiffness value of the SSP muscle was measured by MRE and SWE. The MRE measurement was performed with 0.3 T open MRI and the vibration from a pneumatic driver system with active driver to a passive driver to create the shear wave in the tissue. The passive driver was placed on the center of the SSP muscle. The stiffness was estimated from the wave images using local frequency estimation methods. In the SWE measurement, the probe of the ultrasound was placed on the center of the SSP muscle. The shear wave propagation speed was measured at a depth of 1 cm from the surface, and the stiffness was calculated. After those measurements, the rotator cuff tendon was detached from the greater tuberosity, and MRE and SWE measurements were then performed in the same manner again. The differences in the stiffness values were compared between before and after the rotator cuff tendon tear on both the MRE and SWE measurements. The results indicated that stiffness values on MRE and SWE were 9.3 ± 1.8 and 10.0 ± 1.2 kPa respectively before the rotator cuff tear, and 7.3 ± 1.3 and 8.0 ± 0.8 kPa respectively after the tendon detachment. Stiffness values were significantly lower after the tendon detachment on both the MRE and SWE measurements (p < 0.05). Our results demonstrated that stiffness values of the SSP muscle on MRE and SWE were lower after rotator cuff detachment. From this result, MRE may be a feasible method for quantification of the change in rotator cuff muscle stiffness.

Anatomic Analysis of the Attachment of the Posteroinferior Labrum and Capsule to the Glenoid: A Cadaveric Study.

PURPOSE: To measure the height of the posteroinferior glenohumeral ligament (PIGHL) attachment to the labrum and the depth of the posteroinferior labrum to the glenoid, macroscopically, and to investigate the morphology of the attachment of the posteroinferior labrum to the glenoid, histologically. METHODS: Fifty cadaveric shoulders without exposed subchondral bone on the glenoid and detached posterior labrum were used. We examined the frequency of the heights of the PIGHL attachments to the labrum and the length of the labral attachment on the glenoid rim at the 7, 8, 9, and 10 o'clock positions, macroscopically. According to morphology of the histological labral attachments, it was divided into 3 groups. Labra attached on the articular surface and the glenoid neck were defined as the SN type, while labra attached only to the glenoid neck constituted labra attached to the bone and side of the articular cartilage (Nc type) and labra attached only to bone (Nb type). RESULTS: The PIGHL attached from 7 o'clock to 9 o'clock in 48 shoulders (96%). The mean labral attachment at the 7 o'clock position was 6.3 ± 1.0 mm (range, 4.6-9.4 mm), which was significantly longer than at the other positions (P < .05). Histologically, the frequency of SN type attachment was 49 (98%) shoulders at the 7 o'clock position. CONCLUSIONS: The PIGHL attached between 7 and 9 o'clock in 96% of the shoulders. In 98% of the shoulders, the labrum did not attach to the articular surface, but attached to both the articular cartilage and the bone of the glenoid neck at 7 o'clock. CLINICAL RELEVANCE: The posteroinferior labrum should be repaired widely at the 7 o'clock position and not on the articular surface because the labrum attached anatomically to the glenoid neck.

Anchor placement to glenoid rim during Bankart repair recreates contact area of anterior capsulolabral complex on glenoid better than onto articular surface.

PURPOSE: This study aimed to compare the contact areas of Bankart repair with suture anchors placed on the articular surface of the glenoid versus at the rim of the glenoid because it is unclear which technique most effectively restores the footprint after Bankart repair. METHODS: Ten fresh frozen cadaveric shoulders (mean age 70.7 years) were dissected. The attachment site of the capsulolabral complex from the 1 o' clock position to the 6 o'clock position was marked with ink, and the contact area of the anterior-inferior capsulolabral complex on the glenoid neck was measured using imageJ. Bankart lesions were created, and two types of Bankart repair were performed on each specimen. The suture anchors were inserted at the glenoid rim (Rim group) and onto the glenoid articular surface 2 mm from the rim (Surface group). Using pressure-sensitive films, we examined the interface contact area. RESULTS: The Rim group recreated 64.9% of the native surface area, while the Surface group recreated 47.3% of the area. The Rim group recreated significantly greater contact area compared to the Surface group (P = 0.0008). CONCLUSION: The anchor placement to the glenoid rim recreates the footprint of the capsulolabral complex on the anterior inferior glenoid better than the anchor placement onto the articular surface.

Bankart repair alone in combined Bankart and superior labral anterior-posterior lesions preserves range of motion without compromising joint stability.

HYPOTHESIS: The purpose was to investigate joint stability and range of motion after a Bankart repair without superior labral anterior-posterior (SLAP) repair (termed "Bankart repair") and after combined Bankart and SLAP repairs (termed "combined repair"). METHODS: Eight fresh-frozen shoulders were used. Combined Bankart and SLAP lesions were created (10- to 6-o'clock positions). The labrum and capsule were repaired at the 2-o'clock, 3:30 clock-face, and 5-o'clock positions in the Bankart repair group and at the 11-o'clock, 1-o'clock, 2-o'clock, 3:30 clock-face, and 5-o'clock positions in the combined repair group. The internal- and external-rotation ranges of motion were determined with the arm positioned at 0° and 60° of glenohumeral abduction. The rotation angle was defined when a constant torque of 200 N-mm was applied. Joint stability was measured with a custom stability-testing device. The peak translational force in the anterior-posterior direction was measured with the arm at the end range of external rotation. RESULTS: External rotation angles were greater at 0° and 60° of abduction in the Bankart repair group than in the combined repair group (0° of abduction, P < .01; 60° of abduction, P < .05). The internal rotation angle was greater at 60° of abduction in the Bankart repair group than in the combined repair group (P < .01). The stability between the 2 groups was not significantly different (P = .60). CONCLUSION: In patients with combined Bankart and SLAP lesions and the need for a wide range of motion, a Bankart repair alone may provide a greater range of motion without compromising the joint stability at the end range compared with a combined repair.

Association of Superoxide-Induced Oxidative Stress With Rotator Cuff Tears in Human Patients.

Rotator cuff degeneration is one of the factors contributing to rotator cuff tears. Oxidative stress is involved in tendon degeneration, and superoxide-induced oxidative stress plays a pathological role in regulating the balance between oxidation and reduction. The role of oxidative stress in rotator cuff tears, however, is unclear. This study, therefore, aimed to investigate the contribution of superoxide-induced oxidative stress to rotator cuff tears. Seventy patients were recruited and divided into two groups: patients with (Ruptured group) and those without (Unruptured group) a rotator cuff tear. Specimens from both groups were collected during surgery. Degeneration morphology was classified according to the degeneration score. Superoxide-induced oxidative stress was assessed according to dihydroethidium (DHE) relative fluorescence intensity, capacity for antioxidation according to superoxide dismutase (SOD) activity, and the balance between oxidation and reduction based on the redox ratio. Data were compared between groups. Correlations between the degeneration score and the oxidative stress factors were calculated. Degeneration score and DHE relative fluorescence intensity were significantly higher in the Ruptured than the Unruptured group. The SOD activity was not significantly different between groups. Degeneration score was positively correlated with both DHE relative fluorescence intensity and SOD activity. Thus, superoxide-induced oxidative stress and tendon degeneration were greater in rotator cuff tear tissues than in those with no tear, suggesting that oxidative imbalance may be involved in degenerative rotator cuff tears. Clinical Relevance: Understanding the mechanisms of superoxide-induced oxidative stress may lead to targeted tissue therapy for degenerative rotator cuff tears. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:212-218, 2020.

Increased Stiffness of Rotator Cuff Tendons in Frozen Shoulder on Shear Wave Elastography.

OBJECTIVES: To evaluate the stiffness and morphologic characteristics of the capsule, rotator cuff tendons and muscles, coracohumeral ligament (CHL), and long head of the biceps in patients with frozen shoulder using shear wave elastography (SWE) with B-mode ultrasound. METHODS: Thirty-two patients with frozen shoulder were divided into freezing and frozen phases. All patients had limitations of their range of motion without rotator cuff tears. Stiffness was measured by SWE in the supraspinatus (SSp) tendon, infraspinatus (ISp) tendon, SSp muscle, ISp muscle, teres minor muscle, upper and lower trapezius muscles, posterior capsule, CHL, and long head of the biceps. The posterior capsule and CHL thicknesses were also investigated with B-mode ultrasound. All values were compared in the affected and unaffected shoulders in each phase. RESULTS: The SWE values for the SSp and ISp tendons in the freezing phase and the CHL in the frozen phase were significantly greater on the affected side than the unaffected side (mean ± SD, 280.4 ± 125.3 versus 178.1 ± 73.3, 318.4 ± 110.7 versus 240.8 ± 91.5, and 287.2 ± 135.3 versus 214.1 ± 91.1 kPa, respectively; P < .05). The posterior capsule in both the freezing and frozen phases and the CHL in the frozen phase were significantly thicker on the affected side than the unaffected side (1.3 ± 0.2 versus 0.9 ± 0.3, 1.2 ± 0.4 versus 0.9 ± 0.3, and 4.4 ± 1.4 versus 3.3 ± 1.1 mm; P < .01). CONCLUSIONS: The SWE values of the both SSp and ISp tendons increased in the freezing phase, and that of the CHL also increased in the frozen phase. Not only the change in thickness of the capsule but also the change in stiffness of the rotator cuff may correlate with frozen shoulder.