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Reverse shoulder arthroplasty (RSA) and superior capsular reconstruction (SCR) are recognized as surgical options for an irreparable rotator cuff tear (RCT). However, the postoperative changes of the muscle activity patterns remain unclear.To investigate the quantified muscle activities on shoulder elevation in patients treated with RSA or SCR using fluorine-18-labelled (Asymptomatic shoulders that underwent RSA or SCR and those without an RCT were analyzed as the RSA, SCR and control groups. All subjects underwent shoulder elevation exercise, followed by anThe deltoid muscle showed the most characteristic differences according to the surgeries. The mean SUVs of the anterior, middle, and posterior deltoid were 3.3, 3.7 and 1.5 for the RSA group, 2.7, 4.2 and 1.5 for the SCR group, and 1.3, 2.0 and 0.9 for the control group, respectively. In comparison to the control group, both the RSA and SCR groups showed significantly increased SUVs at all portions of the deltoid muscle. The RSA group showed similar SUVs for the anterior and middle deltoid, whereas the SCR and control groups showed greatest SUVs at the middle deltoid. In addition, the serratus anterior, levator scapulae, and upper portion of the trapezius in the RSA group showed greater SUVs in comparison to the control group.The deltoid muscle showed increased activity in the RSA and SCR groups. The middle deltoid was mainly used in the SCR group, whereas the anterior and middle deltoid as well as the upward rotator muscles of the scapula were mainly used in the RSA group.

Rotator cuff tears are common in the older population. Atrophy and fat infiltration develop un-evenly in torn supraspinatus (SSP) muscles leading to pre- and post-surgical complications. The purpose of the current study was twofold: first, to implement a volumetric and quantitative magnetic resonance imaging (MRI) approach to quantify the degree of muscle atrophy and fat infiltration within the SSP muscle and its four sub-regions (AS, PS, AD, and PD); second to compare 3-D MRI outcomes to the standard 2-D assessment and investigate their relationship with tear size. Fifteen cadaveric shoulders were obtained and MRI performed. Quantitative 3-D outcomes included SSP muscle volume, fossa volume, fat-free muscle volume, and fat fraction for the whole SSP muscle and its four sub-regions. 2-D and qualitative measurements included tear size, 2-D fat infiltration using the Goutallier classification, tangent sign, and occupation ratio. Linear regression outcomes with tear size were not significant for both cross-sectional area (r = − 0.494, p = 0.061) and occupation ratio (r = − 0.011, p = 0.969). Tear size negatively correlated with fat-free muscle volume for both AS and PS sub-regions (AS: r = − 0.78, p

Background Bony defects are common injuries associated with anterior shoulder dislocation. It is generally thought that these bony defects are created at the time of dislocation. However, there have been no biomechanical reports demonstrating the exact time point when these lesions occur. The purpose of this study was to clarify when, how, and which types of bony defects were created during experimental dislocation in cadaveric shoulders. Methods Fifteen fresh-frozen cadaveric shoulders (mean age at the time of death, 79 years) were fixed in a custom testing machine. First, the glenohumeral joint was inspected by arthroscopy. Then, the arm was held at 60° of abduction and maximum external rotation and was manually extended horizontally under fluoroscopy until an anterior dislocation occurred. Next, a force of 800 N was applied to a Kirschner wire inserted in the humeral head in the direction of the pectoralis major with use of an air cylinder. We waited until the arm came to equilibrium under this condition. Finally, the glenohumeral joint was arthroscopically examined. We further performed x-ray micro–computed tomography and histologic examination in 1 shoulder with a bipolar lesion. Results After the anterior dislocation, a Bankart lesion was created in 9 of 15 shoulders and a fragment-type glenoid defect (avulsion fracture) was created in 4. A Hill-Sachs lesion, on the other hand, was not observed after the dislocation. The equilibrium arm position was 40° ± 17° in flexion, 45° ± 22° in abduction, and 27° ± 19° in external rotation. In this arm position, newly created lesions were Hill-Sachs lesions in 6 shoulders and erosion-type glenoid defects (compression fracture) in 7. Micro–computed tomography, performed in a single specimen, showed a flattened anterior glenoid rim with collapse of trabecular bone. Histologic analysis of nondecalcified sections using hematoxylin-eosin staining indicated that the anterior rim of the glenoid was compressed and flattened. The cortex of the anterior glenoid rim could be clearly observed. Conclusion The fragment-type glenoid defect (avulsion fracture) was observed at the time of dislocation, whereas the erosion-type defect (compression fracture) was observed when the arm came to equilibrium in the midrange of motion. Hill-Sachs lesions were created not at the time of dislocation but after the arm came to equilibrium.

Background The purpose was to determine the risk and outcomes of primary shoulder arthroplasties in patients with immunosuppression who had undergone solid organ transplantation. Methods Using a single institution's total joint registry, we reviewed 30 primary shoulder arthroplasties in 25 post-transplantation patients, including 12 total shoulder arthroplasties, 10 hemiarthroplasties, and 8 reverse shoulder arthroplasties, between 1985 and 2012. Therapy and patient variables were recorded, including immunosuppressive therapy protocols, the date of preceding solid organ transplantation, and specific medications taken in the perioperative period. We matched a cohort of control patients for age, sex, type of implant, and year of surgery at a ratio of 4:1. Two groups were compared regarding mortality risk, complications, and clinical outcomes (pain score, range of motion, and American Shoulder and Elbow Surgeons score). Results No periprosthetic infections occurred in the post-transplantation group at a mean follow-up of 39 months. However, the post-transplantation group showed an increased risk of periprosthetic fractures compared with the control group (hazard ratio, 8.18; 95% confidence interval, 1.22-70.98; P = .03). Despite the increase in fractures, the overall number of complications did not differ between the groups. Furthermore, postoperative shoulder function and outcome scores were not significantly different between patients who had a prior transplant and those who did not. Conclusion Primary shoulder arthroplasty in patients with immunosuppression who underwent solid organ transplantation is a successful procedure to treat glenohumeral arthritis. In contrast, there may be an increased risk of periprosthetic fractures in patients with a history of a solid organ transplant.

A curved-drill guide system was recently introduced to achieve a better trajectory for a low anteroinferior anchor during arthroscopic Bankart repair. However, the clinical performance of such a device remains unclear. The purpose of this study was to evaluate the trajectory and position of the low anteroinferior suture anchor with use of the curved-guide system in clinical cases.We enrolled 41 cases of arthroscopic Bankart repair in this study. Of these cases, 9 were repaired using the curved drill guide whereas 32 were repaired using a conventional straight guide. Postoperative computed tomography scans were obtained, and 3-dimensional models of the scapula were reconstructed. Notable perforations of the opposite cortex by the most inferior anchors were recorded. The clock-face angle, insertion angle, and insertion distance were measured.The anchor perforation rate in the curved-guide group (11%) was significantly lower than that in the straight-guide group (56%) (P = .02). The insertion distance in the curved-guide group was significantly shorter than that in the straight-guide group (4.0 ± 1.6 mm vs. 7.0 ± 2.4 mm, P.01). The clock-face angle and insertion angle were significantly greater in the perforated straight-guide group than in the nonperforated groups. The percentage of anchors in the absolute safe zone (clock-face angle135° and165° and insertion angle100°), where no anchors perforated, was greater in the curved-guide group than the straight-guide group.Compared with the conventional straight guide, the curved-guide system provides better placement of the most inferior suture anchor during arthroscopic Bankart repair.

Background: The glenoid track concept has been widely used to assess the risk of instability caused by a bipolar lesion. The mean glenoid track width is reported to be 83% of the glenoid width. However, this width seems to be affected by the range of motion of the shoulder. By clarifying the relationship between the range of shoulder motion and the glenoid track width, a more precise determination of the glenoid track width for each individual could be possible. Purpose: To determine the relationship between the glenoid track width and the range of motion of healthy volunteers. Study Design: Descriptive laboratory study. Methods: Magnetic resonance imaging was taken in 41 shoulders of 21 healthy volunteers (mean age, 32 years) with the arm in maximum horizontal extension, with the arm kept in 90° of abduction and 90° of external rotation. Three-dimensional surface bone models of the glenoid and the humerus were created with image analysis software. The distance from the anterior rim of the glenoid to the medial margin of the footprint of the rotator cuff tendon was defined as the glenoid track width. Active and passive ranges of shoulder motion were measured in the supine and sitting positions. The correlations between the glenoid track width and the ranges of shoulder motion were investigated with Pearson correlation coefficients. Intra- and interobserver reliabilities based on the intraclass correlation coefficient were also analyzed to assess the reliability of the glenoid track measurement. Results: The intra- and interobserver reliabilities for the glenoid track measurement were excellent (0.988 and 0.988, respectively). Among all the measurements, the glenoid track width and the active range of motion in horizontal extension in the sitting position showed the greatest correlation coefficient ( r = −0.623, P < .0001). A correlation between the glenoid track width and this angle was expressed as Y = −0.49 X + 90, where X is the horizontal extension angle (degrees) and Y is the glenoid track width (percentage of glenoid width). Conclusion: The present data demonstrate that the greater the horizontal extension angle in abduction and external rotation, the smaller the glenoid track width. An individualized glenoid track width can be obtained by measuring the active horizontal extension angle with the arm in abduction and external rotation in the sitting position. Clinical Relevance: An individualized glenoid track width enables selection of a more precise surgical option by the on-track/off-track concept.

Background: Ultrasonographically measuring the median nerve cross-sectional area (MN-CSA) is a useful and complementary method for diagnosing carpal tunnel syndrome (CTS). This study investigated the usefulness of the median nerve transverse diameter (MN-TD) as a simpler and easier technique than MN-CSA for diagnosing CTS severity. Methods: We examined 145 hands from 101 patients with CTS and 114 age- and gender-matched control hands. Based on the electrodiagnostic findings, the severity of CTS was divided into minimal, mild, moderate, severe and extreme. An ultrasonographic assessment of MN-TD and MN-CSA was performed to measure the maximal values around the carpal tunnel inlet level. The values were assessed for comparisons between the CTS and control groups and for the evaluation of differences by CTS severity. Results: The ultrasonographic measurements of MN-TD and MN-CSA were significantly increased in the CTS group compared to the normal group. Furthermore, both measurements significantly increased with increasing CTS severity. A receiver operating characteristic curve (ROC) analysis showed that participants with MN-TD > 7.2 mm had CTS with 88% specificity and 74% sensitivity, and those with MN-CSA > 12.0 mm2 had CTS with 86% specificity and 84% sensitivity. Conclusions: Ultrasonographic measurement for MN-TD may be useful for diagnosing CTS patients and predicting the severity.

The purposes of this study were to demonstrate the clinical characteristics of patients with persistent second carpometacarpal (CMC) joint pain without bony abnormalities known as the carpal boss, and to assess the clinical efficacy of surgical stabilization of the second CMC joint. Eleven patients had persistent wrist pain with characteristic symptoms, including tenderness over the second CMC joint, increased symptoms when the involved hand was placed on the ground or gripped strongly with the involved hand, a positive metacarpal stress test and temporary pain relief with the intra-articular injection of the lidocaine. The patients underwent arthrodesis of the second CMC joint. All cases showed radiologically confirmed fusion of the second CMC joint. At the final followup examination, 10 of 11 patients resulted in satisfactory clinical outcomes, excepting one patient with remnant pain and restricted range of wrist motions. This report highlights the importance of conducting a careful assessment of patients who present with persistent second CMC joint pain without the bony abnormalities, such as carpal bossing. Surgery to stabilize the second CMC joint may be an option to improve their symptoms when conservative treatment fails.

Objectives: The purposes of this study were to assess the clinical features of ulnar tunnel syndrome (UTS) and to investigate the diagnostic value of nerve conduction measurements for UTS. Methods: Eighteen patients with UTS were reviewed retrospectively. Fifteen patients had intrinsic muscle atrophy and motor weakness, and 15 had numbness with hypesthesia. The compound muscle action potentials (CMAPs) from the first dorsal interosseous (FDI) muscle and the abductor digiti minimi (ADM) muscle and the sensory nerve action potential (SNAP) from the little finger were recorded and analyzed. All patients underwent ulnar tunnel release surgery and neurolysis. Static two-point discrimination test results and pinch strengths were assessed before and after surgery. Results: Before surgery, FDI-CMAP was recorded in 17 patients, and ADM-CMAP in 16, and all showed delayed latency and/or low amplitude. SNAP was recorded in eight patients and two showed delayed latency. The causes of ulnar nerve lesions were ganglion in five patients, traumatic adhesion in four, ulnar artery aberrancy in four, pisohamate arch in three, anomalous muscle in one, and ulnar vein varix in one. The sites of the lesions were in zone 1 of the ulnar tunnel anatomy in 12 patients, in zone 2 in 2, and in zones 1 and 2 in 4. After surgery, all patients obtained recovery of motor function and sensation; however, postoperative FDI-CMAP and ADM-CMAP did not improve to the normal range. Conclusions: The causes of UTS were ganglion, traumatic adhesion, ulnar artery aberrancy, and pisohamate arch. Both FDI-CMAP and ADM-CMAP were valuable for electrophysiological diagnosis of UTS.

Rotator cuff tears are common in the older population. Atrophy and fat infiltration develop un-evenly in torn supraspinatus (SSP) muscles leading to pre- and post-surgical complications. The purpose of the current study was twofold: first, to implement a volumetric and quantitative magnetic resonance imaging (MRI) approach to quantify the degree of muscle atrophy and fat infiltration within the SSP muscle and its four sub-regions (AS, PS, AD, and PD); second to compare 3-D MRI outcomes to the standard 2-D assessment and investigate their relationship with tear size.Fifteen cadaveric shoulders were obtained and MRI performed. Quantitative 3-D outcomes included SSP muscle volume, fossa volume, fat-free muscle volume, and fat fraction for the whole SSP muscle and its four sub-regions. 2-D and qualitative measurements included tear size, 2-D fat infiltration using the Goutallier classification, tangent sign, and occupation ratio.Linear regression outcomes with tear size were not significant for both cross-sectional area (r = - 0.494, p = 0.061) and occupation ratio (r = - 0.011, p = 0.969). Tear size negatively correlated with fat-free muscle volume for both AS and PS sub-regions (AS: r = - 0.78, p 0.001; PS: r = - 0.68, p = 0.005, respectively) while showing no significant correlation with fat fraction outcomes. AD and PD sub-regions positively correlated with tear size and fat fraction outcomes (AD: r = 0.70, p = 0.017; PD: r = 0.52, p = 0.045, respectively), while no significant correlation was observed between tear size and fat-free muscle volumes.Quantitative 3-D volumetric assessment of muscle degeneration resulted in better outcomes compared to the standard 2-D evaluation. The superficial supraspinatus muscle sub-regions primarily presented muscle atrophy, while the deep sub-regions were mainly affected by fat infiltration. 3-D assessments could be used pre-surgically to determine the best course of treatment and to estimate the muscles' regenerative capacity and function.

Background Focus has recently been on the critical shoulder angle (CSA) as a factor related to rotator cuff tear and osteoarthritis (OA) in the European population. However, whether this relationship is observed in the Asian population is unclear. Methods The correlation between the CSAs measured on anteroposterior radiographs and the presence or absence of rotator cuff tears or OA changes was assessed in 295 patients. Rotator cuff tears were diagnosed with magnetic resonance imaging or ultrasonography. OA findings were classified using the Samilson-Prieto classification. The CSAs among the patients with rotator cuff tears, OA changes, and those without pathologies were compared. Multivariable analyses were used to clarify the potential risks for these pathologies. Results The mean CSA with rotator cuff tear (33.9° ± 4.1°) was significantly greater than that without a rotator cuff tear (32.3° ± 4.5°; P = .002). Multivariable analysis also showed that a greater CSA had a significantly increased risk of rotator cuff tears, with the odds ratio of 1.08 per degree. OA findings showed no significant correlation to the CSAs. Conclusions Our study demonstrates that the CSA is greater in those with a rotator cuff tear than in those without a tear or OA changes, which may be an independent risk factor for the incidence of rotator cuff tears in the Japanese population.

Treatment with injection of collagenase Clostridium histolyticum (CCH) has been recognized as an effective option for the Dupuytren's contracture (DC) in Europe and North America. However, there are no studies describing mid-term efficacy of CCH treatment in East-Asian population. The purpose of this study was to assess 2-year outcomes following CCH treatment in Japanese patients.Twenty hands (28 joints) from 18 DC patients underwent CCH injection with manipulation according to the product specifications with 2-year follow-up. Patients were assessed for extension deficit on treated metacarpophalangeal (MCP) and/or proximal interphalangeal (PIP) joints before treatment, at 4 weeks and 2 years after the treatment.At 4 weeks after CCH treatment, contracture of treated joints significantly improved from the mean extension deficit of 45° before treatment to 3° for MCP joints, and from 41° to 14° for PIP joints (P 0.001,0.001, respectively). Improved contracture was maintained with 4° and 23° at 2 years after CCH treatment (P 0.001,0.05, respectively). Successful correction defined as ≤ 5° extension deficit was obtained in 14/16 MCP and 5/12 PIP joints at 4 weeks; of these, 11 MCP and 1 PIP joints maintained the corrected range of motion at 2-year follow-up.CCH treatment could be a useful option to improve contracture in Japanese patients. During 2-year follow-up, this treatment could provide comparable effect durability to previous studies from Western countries. Moreover, our results support the evidence that better correction of the contracture can be obtained in the MCP joints than PIP joints after CCH treatment.

The rotator cuff tendon undergoes degeneration and tear quite commonly in the elderly population and was rarely observed in patients under 50 years of age. In addition to ageing, smoking, diabetes mellitus and other comorbidities are known to be the risk factors of tendon tear. Bony anatomy of the acromion relative to the glenoid plays a role on the onset of degenerative cuff tears. The biological responses of chronic tendinopathy, degenerative tear and the following muscle atrophy and fatty infiltration are regulated by macrophages. Age, tear size and chronicity have direct influence on healing after rotator cuff repair. Systematic reviews have shown that there is better healing in larger tears with a double row repair compared with a single row repair, but no differences in clinical outcome. The tendon healing is characterised by a fibrovascular scar response rather than by regenerating normal tendon tissue. As a result, the material and structural properties are much weaker than the normal tendon-to-bone interface. With this knowledge, better repair techniques and repair methods are expected to be developed for better healing of the tendon.

Background Immobilization with shoulder braces is used for conservative treatment of an initial shoulder dislocation. Various arm positions have been investigated to determine optimal position in terms of the anatomical reduction of the Bankart lesion. Recently, the effect of immobilization in shoulder abduction as well as in external rotation has been reported. However, there are few studies assessing subjects' acceptability of the brace in various arm positions. We hypothesized that a certain arm position regarding abduction or external rotation for immobilization would induce significant discomfort during activities of daily living. Methods A dominant arm of 20 healthy participants was immobilized with a shoulder brace in 4 different positions; adduction and internal rotation (Add-IR), adduction and external rotation (Add-ER), 30° of abduction and 30° of external rotation (Abd-30ER), and 30° of abduction and 60° of external rotation (Abd-60ER). After completing immobilization for 24 h, subjects were asked to assess the discomfort of bracing for overall and individual activities, using a visual analogue scale. Data were compared among the four positions. Results For overall activities and several activities (eating, reading books, and removing and putting on pants), Abd-60ER was significantly more uncomfortable than adducted arm positions. Abd-30ER did not show any differences compared to the other arm positions. Conclusion Immobilization in abduction and external rotation seems to be acceptable although the arm position in 30° of abduction and 60° of external rotation is less comfortable than the others. Our results might be useful in determining and developing the ideal shoulder brace which could keep patients' compliance and improve their outcomes.

Background: It has been demonstrated biomechanically that 25% is a critical size defect of the glenoid. However, a recent clinical study reported that a bone loss between 13.5% and 20% (subcritical bone loss) led to impairment of quality of life but not a recurrence of instability. Purpose: To clarify whether a subcritical bone loss exists in assessing a Hill-Sachs lesion via a disease-specific quality of life questionnaire. Study Design: Cohort study; Level of evidence, 3. Methods: Fifty patients (mean age, 27 years) with Results: The recurrence rate was 6% (3 of 50 shoulders). The Rowe score significantly improved from 45.2 ± 4.7 (mean ± SD) preoperatively to 92.3 ± 6.5 at the final follow-up ( P < .05). The WOSI score also significantly increased from 46.6% ± 19.3% preoperatively to 72.3% ± 21.0% at the final follow-up ( P < .001). The WOSI score of patients in zone 4 (peripheral-track lesion) (n = 10) was significantly lower than those in the other zones (central-track lesion) ( P = .0379). Of the 10 patients with the peripheral-track lesion, 5 had a Conclusion: Patients with on-track lesions can be divided into 2 subgroups: those with the Hill-Sachs occupancy ≥75% (peripheral-track lesion) showed significantly worse WOSI score without recurrent instability events than those with the Hill-Sacks occupancy

Background:It has been believed that a Hill-Sachs lesion (HSL) is created with the arm in abduction and external rotation at the time of dislocation. However, no studies have clarified the arm position in which an HSL is created.Purpose:To determine the arm position in which an HSL is created.Study Design:Descriptive laboratory study.Methods:The computed tomography images of 100 shoulders of 100 patients (72 males and 28 females; mean age, 30 years old) with recurrent anterior dislocation of the shoulder were investigated using an image analyzing software. Three-dimensional surface bone models of the scapula and humerus were created separately. The humerus was moved so that the HSL perfectly fit the anterior rim of the glenoid. This arm position was recorded 3-dimensionally.Results:Considering the scapulohumeral rhythm, the average arm position in which the HSL and the anterior glenoid rim best fit was 74° of abduction, 27° of external rotation, and 3° of horizontal flexion relative to the trunk.Conclusion:The arm position when an HSL and the anterior glenoid rim best fit is 74° of abduction, 27° of external rotation, and 3° of horizontal flexion, which seems to be the arm position when the HSL has been created. This result suggests 2 possibilities: dislocation occurred in this midrange position or HSL was not created at the time of dislocation but later in the mid–range of motion. However, as we have no information on the arm position at the time of dislocation, we cannot conclude which of these possibilities is true in our study.Clinical Relevance:This study gives us a better understanding of the timing of HSL occurrence. Shoulder dislocation may occur at the end range of motion or in the mid–range of motion, but an HSL is created in the mid–range of motion.

Background It remains unclear how the head and stem diameters for the radial head prosthesis could affect mechanical properties of the lateral collateral ligament measured by strain changes during elbow and forearm motions. Methods Eight cadaveric specimens were secured to the device, which allows elbow flexion-extension and forearm pro-supination. Using six different implant combinations comprising 2 sizes for the head (long- and short-axis of the native head) and 3 sizes for the stem (press-fit, −1 mm, and −2 mm downsizing), prostheses were attached via the posterior approach. A differential variable reluctance transducer placed on the central portion of the radial collateral ligament were used for strain measurement with elbow flexion at 0°, 30°, 60°, and 90°. At each position, the strain patterns with the forearm in the neutral and 45° pro-supination positions were also assessed. Findings Specimens implanted with long-axis head component showed greater increases in the ligament strain during elbow flexion than intact specimens or those implanted with short-axis head. Compared to press-fit stem, implants with downsizing to −1 mm approximated strain patterns during pro-supination with elbow extension to intact condition. Interpretation Morphologic variation of the head and stem components in radial head prostheses led to altered strain patterns in the lateral collateral ligament during elbow and forearm motions. A short-axis head component can be used to prevent excessive strain changes after the prosthesis application. Downsizing of the stem component might be an option for approximating the biomechanics at the radiocapitellar joint during forearm rotation to the intact elbow.

Background The purpose of this study was to assess the clinical outcomes of patients with anterior shoulder instability who underwent surgical treatment according to the on-track/off-track concept. Methods We retrospectively analyzed patients who underwent surgical treatment according to the glenoid track concept with a minimum of 2 years' follow-up. By use of preoperative 3-dimensional computed tomography images, surgical options were selected: arthroscopic Bankart repair (ABR) for patients with on-track lesions and the Latarjet procedure or ABR with the remplissage procedure for patients with off-track lesions. The recurrence rate was assessed at 2-year follow-up after surgery. Results Among 92 patients enrolled in this study, 81 had on-track lesions and underwent ABR. Of the 11 patients with off-track lesions, 1 underwent ABR with the remplissage procedure and 10 underwent the Latarjet procedure. Recurrences occurred in 4 patients treated by ABR (5%), whereas no recurrences were observed in off-track cases treated by the remplissage or Latarjet procedure. Conclusion Clinical application of the on-track/off-track concept for determining surgical options in preoperative planning seems to be useful to prevent recurrent instability after surgery.

Background It has been biomechanically demonstrated that 20% to 25% is a critical glenoid bone loss. Recently, there are several reports describing that a bone loss less than 20% to 25% needed to be treated because patients may have decreased quality of life without recurrent instability events. The purpose of this study was to clarify the presence of subcritical bone loss that would affect postoperative instability or quality of life. Methods Subjects were 43 patients aged ≤ 40 years with less than 25% glenoid bone loss who had undergone arthroscopic Bankart repair. These patients were assessed at a mean follow-up of 32 months. The Western Ontario Shoulder Instability (WOSI) and Rowe scores were used for the clinical evaluation. Patients were divided in 3 groups based on the percentage of bone loss: group 1: 17%. Results The recurrence rate was 7% (3/43 shoulders). A weak negative correlation was seen between bone loss and sports/recreation/work domain of the WOSI score (r = −0.304, p = 0.0191). The WOSI for group 3 was significantly lower than that for group 1 and 2 (p = 0.0009). The male WOSI scores were significantly lower than the female ones (p = 0.0471). The WOSI scores of the contact athletes were significantly lower than those of non-contact athletes (p = 0.0275). All the patients in Group 3 were males and participated in contact sports. Conclusion Glenoid bone loss between 17% and 25% is considered to be a “subcritical bone loss” in our series, especially in male patients who are involved in sports or high-level activities. Level of evidence III, retrospective study.

Osteoid osteoma (OO) apparent in the intra-articular region of the elbow is very rare. Although computed tomography-guided excision and radiofrequency ablation have been recognized as useful treatment options, arthroscopic excision has recently received focus as an alternative strategy for lesions close to neurovascular structures or intra- and juxta-articular lesions. We herein report a 17-year-old female who underwent arthroscopic treatment for intra-articular OO located at the olecranon/coronoid fossa. Her symptoms included elbow pain that was exacerbated at night and contracture of elbow flexion-extension, and she was diagnosed with intra-articular OO after 12 months of symptomatic history. Arthroscopically, thorough synovectomy for both the anterior and posterior aspects of the joint enabled definition of the tumor margin with hyperemic alteration and excision of the lesion as an en bloc specimen. At the 12-month follow-up, the patient had no recurrence of elbow limitation or pain. This case report describes the advantages of arthroscopic treatment, including a low-invasive approach and easy accessibility to the whole intra-articular space, which can provide clear visualization of the tumorous lesion.

Background: The best method for nonsurgical treatment after primary dislocation of the shoulder is not clear. The efficacy of immobilization with the arm in external rotation (ER) compared with internal rotation (IR) remains controversial. Purpose: To determine the efficacy of ER immobilization versus IR immobilization on recurrence rate after primary dislocation of the shoulder from the evidence of randomized controlled trials. Study Design: Systematic review; Level of evidence, 2. Methods: Electronic databases (MEDLINE [Ovid SP], PubMed, Web of Science, EBM reviews, and CINAHL) and available proceedings according to the abstracts of major international meetings related to or including shoulder injuries and trauma were used to search for randomized controlled trials. Two independent investigators determined eligibility and carried out data extraction from the selected studies. Results: A total of 9 studies (817 patients) were selected for this meta-analysis. They included 668 male and 149 female patients, with a mean age ranging from 20.3 to 37.5 years. In the 9 pooled studies, the recurrence rate of shoulder dislocation was 21.5% (84/390) in the ER group versus 34.9% (130/373) in the IR group. ER immobilization significantly reduced the recurrence rate compared with IR immobilization (risk ratio, 0.56; P = .007). In the subgroup analysis of those immobilized full-time, ER immobilization was significantly more effective than IR immobilization in reducing the recurrence rate (risk ratio, 0.57; P = .01). In the subgroup analysis of age, ER immobilization was significantly more effective than IR immobilization in those aged 20 to 40 years but not in those younger than 20 years. Conclusion: This meta-analysis demonstrates that ER immobilization reduces the recurrence rate after primary shoulder dislocation compared with IR immobilization in patients older than 20 years. When treating a patient with primary shoulder dislocation, the clinician should provide this information to the patient before a treatment method is selected.

Background Several measurement techniques have been reported to quantify glenoid bone defect in patients with anterior shoulder instability. Among them, the method that uses a best-fit circle and another that uses the contralateral glenoid as a control are most commonly used. However, to our knowledge, no study has been reported that compared the reliability of these methods. The purpose of this study, therefore, was to determine which of these methods has higher reproducibility. Method In this study, 3-dimensional computed tomography data from 94 patients (mean age 29 years) with unilateral anterior shoulder instability were used. Three examiners measured the glenoid bone defect of each patient 3 times using 2 techniques: the best-fit circle method and the contralateral comparison method. Intra- and interobserver reliabilities were measured using intraclass correlation coefficient (ICC). Results The intraobserver reliability was found to be 0.91 for the best-fit circle method and 0.98 for the contralateral comparison method. The interobserver reliability was 0.77 for the best-fit circle method and 0.88 for the contralateral method. The percentage of glenoid defect was 11.5% when using the best-fit circle and 10.7% with the contralateral method. Conclusion The contralateral comparison method was more reliable than the best-fit circle method for quantifying the amount of glenoid bone loss.

Closed treatment of shoulder dislocation is indicated in those with an initial dislocation without any obvious fractures of the humerus or the glenoid and in those who select conservative treatment. Those who strongly desire to undergo surgical stabilization should be excluded. There are three options of conservative treatment: (1) immobilization in internal rotation; (2) immobilization in external rotation; and (3) skillful neglect. There is evidence that skillful neglect provides the same outcome as immobilization in internal rotation in terms of recurrence rate. Immobilization in external rotation is a new method of conservative treatment. The efficacy is controversial. Recently, immobilization in abduction and external rotation has been reported to be better than in adduction and external rotation in a magnetic resonance imaging study. Based on this study, a prospective randomized clinical trial will be undertaken.

Osteoarthritic findings of the acromioclavicular joint are commonly observed in adult population, especially with increased age. For symptomatic patients who resulted in failed conservative treatment, surgical treatment is needed. In addition to the classic open procedure for distal clavicle resection, the arthroscopic procedure has recently been popularized. There have been some studies describing the advantages of the arthroscopic procedure including faster return to activities and less complication rate than the open procedure. There are two approaches in arthroscopic procedure: the lateral subacromial (indirect) approach and the superior (direct) approach. The latter approach has advantage to preserve the inferior AC ligament and coracoacromial arch during the surgery. The amount of resection has been discussed in anatomical studies regarding the AC ligament insertion. The dynamic examination during arthroscopy is helpful in determining the optimal amount of resection.

Background A torn rotator cuff tendon will retract over time causing changes in muscle properties and decreasing its extensibility, or deformation. During surgery, large tensile loads are applied to bring the torn tendon to the footprint. Poor muscle extensibility and large tensile stresses at the repair might lead to gap formation or re-tear of the repair. A quantitative evaluation of muscle properties could be used to predict the extensibility of the supraspinatus (SSP) muscle. Method Magnetic resonance imaging (MRI)-measured volumetric fat fraction and shear wave elastography (SWE)-measured elastic modulus of the SSP muscle were obtained on seventeen cadaveric shoulders. Experimental extensibility and stiffness were then measured by axially pulling the tendon up-to 60 N. Univariate and multivariate analyses were used to determine the correlation and contribution of fat fraction and elastic modulus to experimental outcomes. Findings SWE moduli negatively correlated with SSP muscle extensibility (r = 0.54–0.58, P ≤ 0.0259); fat fraction resulted in a positive correlation (r = 0.69, P = 0.0021). SWE measurements, solely, explained up to 34% and 33% of the variability in measured extensibility and stiffness, respectively. Fat Fraction, solely, explained 48% of the variability in extensibility and 36% of the variability in stiffness. These methods combined predicted up to 62% of the musculotendinous extensibility. Interpretation This study showed a comprehensive quantitative assessment of SSP muscle properties using SWE to estimate stiffness and MRI to measure fatty infiltration. The extensibility of the detached muscle/tendon unit was highly correlated to material properties of the muscle when these methods were used in combination.

Background: Shoulder dislocation often recurs, especially in the younger population. Immobilization in external rotation, in which a Bankart lesion is displaced in the anterior, medial, and inferior directions, was introduced as a new method of nonoperative treatment, but its clinical efficiency is controversial. In terms of reducing the lesion, it is reasonable to incorporate not only external rotation, which makes the anterior soft tissues tight to push the lesion posteriorly and laterally, but also abduction, which makes the inferior soft tissues tight to push the lesion superiorly. Hypothesis: Abducting the arm during immobilization in external rotation will improve the reduction of a Bankart lesion. Study Design: Controlled laboratory study. Methods: There were 37 patients with initial shoulder dislocation enrolled in this study. After reduction, MRI was taken in 4 positions of the shoulder: adduction and internal rotation (Add-IR), adduction and external rotation (Add-ER), 30° of abduction and 30° of external rotation (Abd-30ER), and 30° of abduction and 60° of external rotation (Abd-60ER). On radial slices, the separation, displacement of the labrum, and opening angle of the capsule were measured. Results: Add-ER improved the reduction of the anterior labrum but not the inferior labrum when compared with Add-IR. Both Abd-30ER and Abd-60ER improved the reduction of the inferior labrum as compared with Add-IR. Furthermore, Abd-60ER improved the reduction more than Add-ER. Conclusion: Among the 4 positions tested, Abd-60ER is the best position in terms of reducing the Bankart lesion. Clinical Relevance: Abducting the shoulder during immobilization in external rotation is demonstrated to improve the reduction of the Bankart lesion. Therefore, this position is expected to reduce the recurrence rate after initial dislocation of the shoulder. Future clinical trials are necessary.

Surgical repair of rotator cuff tears presents a significant clinical challenge with high failure rates and inferior functional outcomes. Graft augmentation improves repair outcomes; however, currently available grafting materials have limitations. Although cell-seeded decellularized tendon slices may facilitate cell infiltration, promote tendon incorporation, and preserve original mechanical strength, the unique fibrocartilage zone is yet to be successfully reestablished. In this study, we investigated the biological and mechanical properties of an engineered tendon-fibrocartilage-bone composite (TFBC) with cyclic tension (3% strain; 0.2 Hz). Decellularized TFBCs seeded with bone marrow-derived mesenchymal stem cell (BMSCs) sheets and subjected to mechanical stimulation for up to 7 days were characterised by histology, immunohistochemistry, scanning electron microscopy, mechanical testing, and transcriptional regulation. The decellularized TFBC maintained native enthesis structure and properties. Mechanically stimulated TFBC-BMSC constructs displayed increased cell migration after 7 days of culture compared with static groups. The seeded cell sheet not only integrated well with tendon scaffold but also distributed homogeneously and aligned to the direction of stretch under dynamic culture. Developmental genes were regulated including scleraxis, which was significantly upregulated with mechanical stimulation. The Young's modulus of the cell-seeded constructs was significantly higher compared with the noncell-seeded controls. In conclusion, the results of this study reveal that the TFBC-BMSC composite provides an ideal multilayer construct for cell seeding and growth, with mechanical preconditioning further enhances cell penetration and differentiation. The BMSC cell sheet revitalised TFBC in conjunction with mechanical stimulation could serve as a novel and primed biological patch to improve rotator cuff repair.

Surgical repair is a common treatment for rotator cuff tear; however, the retear rate is high. A high degree of suture repair strength is important to ensure rotator cuff integrity for healing. The purpose of this study was to compare the mechanical performance of rotator cuffs repaired with a mesh suture versus traditional polydioxanone suture II and FiberWire sutures in a canine in vitro model. Seventy-two canine shoulders were harvested. An infraspinatus tendon tear was created in each shoulder. Two suture techniques-simple interrupted sutures and two-row suture bridge-were used to reconnect the infraspinatus tendon to the greater tuberosity, using three different suture types: Mesh suture, polydioxanone suture II, or FiberWire. Shoulders were loaded to failure under displacement control at a rate of 20 mm/min. Failure load was compared between suture types and techniques. Ultimate failure load was significantly higher in the specimens repaired with mesh suture than with polydioxanone suture II or FiberWire, regardless of suture technique. There was no significant difference in stiffness among the six groups, with the exception that FiberWire repairs were stiffer than polydioxanone suture II repairs with the simple interrupted technique. All specimens failed by suture pull-out from the tendon. Based on our biomechanical findings, rotator cuff repair with the mesh suture might provide superior initial strength against failure compared with the traditional polydioxanone suture II or FiberWire sutures. Use of the mesh suture may provide increased initial fixation strength and decrease gap formation, which could result in improved healing and lower re-tear rates following rotator cuff repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:987-992, 2018.

Surgical repair for large rotator cuff tear remains challenging due to tear size, altered muscle mechanical properties, and poor musculotendinous extensibility. Insufficient extensibility might lead to an incomplete reconstruction; moreover, excessive stresses after repair may result in repair failure without healing. Therefore, estimates of extensibility of cuff muscles can help in pre-surgical planning to prevent unexpected scenarios during surgery. The purpose of this study was to determine if quantified mechanical properties of the supraspinatus muscle using shear wave elastography (SWE) could be used to predict the extensibility of the musculotendionous unit on cadaveric specimens. Forty-five fresh-frozen cadaveric shoulders (25 intact and 20 with rotator cuff tear) were used for the study. Passive stiffness of 4 anatomical regions in the supraspinatus muscle was first measured using SWE. After detaching the distal edge of supraspinatus muscle from other cuff muscles, the detached muscle was axially pulled with the scapula fixed. The correlation between the SWE modulus and the extensibility of the muscle under 30 and 60 N loads was assessed. There was a significant negative correlation between SWE measurements and the experimental extensibility. SWE modulus for the anterior-deep region in the supraspinatus muscle showed the strongest correlation with extensibility under 30 N (r = 0.70, P < 0.001) and 60 N (r = 0.68, P < 0.001). Quantitative SWE assessment for the supraspinatus muscle was highly correlated with extensibility of musculotendinous unit on cadaveric shoulders. This technique may be used to predict the extensibility for rotator cuff tears for pre-surgical planning.

Surgical repair is a common treatment for rotator cuff tear; however, the retear rate is high. A high degree of suture repair strength is important to ensure rotator cuff integrity for healing. The purpose of this study was to compare the mechanical performance of rotator cuffs repaired with a mesh suture versus traditional polydioxanone suture II and FiberWire sutures in a canine in vitro model. Seventy-two canine shoulders were harvested. An infraspinatus tendon tear was created in each shoulder. Two suture techniques-simple interrupted sutures and two-row suture bridge-were used to reconnect the infraspinatus tendon to the greater tuberosity, using three different suture types: Mesh suture, polydioxanone suture II, or FiberWire. Shoulders were loaded to failure under displacement control at a rate of 20 mm/min. Failure load was compared between suture types and techniques. Ultimate failure load was significantly higher in the specimens repaired with mesh suture than with polydioxanone suture II or FiberWire, regardless of suture technique. There was no significant difference in stiffness among the six groups, with the exception that FiberWire repairs were stiffer than polydioxanone suture II repairs with the simple interrupted technique. All specimens failed by suture pull-out from the tendon. Based on our biomechanical findings, rotator cuff repair with the mesh suture might provide superior initial strength against failure compared with the traditional polydioxanone suture II or FiberWire sutures. Use of the mesh suture may provide increased initial fixation strength and decrease gap formation, which could result in improved healing and lower re-tear rates following rotator cuff repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:987-992, 2018.

Pre-surgical measurement of supraspinatus muscle extensibility is important for rotator cuff repair. The purpose of the present study was to explore the potential feasibility of a shear wave ultrasound elastography (SWE)-based method, combined with B-mode ultrasound, to measure the in vivo stiffness of the supraspinatus muscle non-invasively and thus obtain key information about supraspinatus muscle extensibility. Our investigation comprised two steps. First, we determined the orientation of the supraspinatus muscle fibers in cadaveric shoulders without rotator cuff tear in order to optimize the ultrasound probe positions for SWE imaging. Second, we investigated the feasibility of quantifying the stiffness of the normal supraspinatus muscle by SWE in vivo. The supraspinatus muscle was divided into four anatomical regions: anterior superficial (AS), posterior superficial (PS), anterior deep (AD), and posterior deep (PD). Each region was examined by SWE. The SWE stiffnesses of AD, AS, PD, and PS were 40.0 ± 12.4, 34.0 ± 9.9, 32.7 ± 12.7, 39.1 ± 15.7 kPa, respectively. SWE combined with B-Mode ultrasound imaging could be a feasible method for quantifying the local stiffness of the rotator cuff muscles. Clin. Anat. 28:213–218, 2015. © 2014 Wiley Periodicals, Inc.