Comparison of Hook Plate Fixation Versus Arthroscopic Coracoclavicular Fixation Using Multiple Soft Anchor Knots for the Treatment of Acute High-Grade Acromioclavicular Joint Dislocations.

PURPOSE: To compare the clinical and radiologic outcomes of arthroscopically assisted coracoclavicular (CC) fixation using multiple soft anchor knots versus hook plate fixation in patients with acute high-grade Rockwood type III and V acromioclavicular (AC) joint dislocations. METHODS: This retrospective study included 22 patients with acute Rockwood type III and V AC joint dislocations who underwent arthroscopic fixation or hook plate fixation surgery between February 2016 and March 2018. Patients were categorized into 2 groups: arthroscopically assisted CC fixation using multiple soft anchor knots group (AR, n = 12) and hook plate fixation group (HO, n = 10). We measured the CC distances (CCDs) and CCD ratio at 6 months, 1 year, and last follow-up postoperatively to compare the radiologic results between the groups. Clinical outcomes were assessed at 1 year postoperatively and at the last follow-up using the Visual Analog Scale, American Shoulder and Elbow Surgeons (ASES) scores, and Shoulder Pain and Disability Index (SPADI) scores, and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. Magnetic resonance imaging after hook plate removal was used to evaluate the healing ligaments and tendon-bone interface. RESULTS: The patients in the AR group had better ASES, SPADI, and Quick DASH scores than the patients in the HO group at 1 year postoperatively and at last follow-up. The CCD and CCD ratio were significantly better in the AR group than in the HO group at the last follow-up period (P = .007/0.029). Magnetic resonance imaging findings showed grade I in 60% of patients in the AR group and grade III in 60% of patients in the HO group. AC joint arthritic change was observed in 40% of the HO group. CONCLUSIONS: The CC fixation method using multiple soft anchor knots showed satisfactory results and had superior CC ligament healing ability and maintenance of CCD than hook fixation. LEVEL OF EVIDENCE: Level III, retrospective therapeutic comparative investigation.

Effect of suprascapular nerve injury on rotator cuff enthesis.

BACKGROUND: Numerous reports have shown that retracted rotator cuff tears may cause suprascapular nerve injury, and nerve injury causes atrophy and fat accumulation in the rotator cuff muscles. However, the effect of suprascapular nerve injury on rotator cuff enthesis has not been directly defined. This study aimed to investigate the effect of suprascapular nerve injury on rotator cuff enthesis. METHODS: Twenty-four Wistar albino rats underwent bilateral transection of the suprascapular nerve. Additional 6 rats were used as the sham group. Bilateral supraspinatus and infraspinatus entheses were examined after 1, 4, 8, and 12 weeks of nerve transection. Histomorphometric analyses were performed for each zone of enthesis. RESULTS: Compared with normal enthesis, significant and consistent decrease in cellularity were observed in the tendon and bone at all time points (P < .001). Collagen bundle diameter in the tendon also decreased in a similar manner (P < .001). Apart from the tendon and bone zones, fibrocartilage and calcified fibrocartilage zones showed similar response, and significant decrease in cellularity was observed 8 weeks after nerve transection (P < .001). CONCLUSION: This study identifies suprascapular nerve injury as an underlying mechanism leading to compromise of the rotator cuff enthesis structure. Suprascapular nerve injury may be considered as an etiologic factor for the impaired healing after repair of a massive tear.

Arthroscopic Coracoclavicular Fixation Using Multiple Low-Profile Devices in Acute Acromioclavicular Joint Dislocation.

PURPOSE: To introduce an arthroscopically assisted coracoclavicular (CC) fixation technique using multiple low-profile devices to evaluate the clinical and radiologic outcomes in patients with acute high-grade acromioclavicular (AC) joint dislocation. METHODS: Between July 2014 and September 2015, cases of AC joint dislocation that were treated with arthroscopic CC fixation using multiple low-profile devices with a minimum follow-up of 24 months were included. We measured the vertical coracoclavicular distance (CCD) on the anteroposterior view and the horizontal acromioclavicular distance on 3-dimensional computed tomography images to evaluate the changes in radiologic outcomes before and after surgery. We compared final radiologic outcomes between initial AC reduction groups based on hierarchical clustering. Clinical outcomes were evaluated using the Constant-Murley score. RESULTS: We enrolled 27 patients in total, and the mean follow-up period was 27.2 months. The mean CCD of the injured shoulder was 13.68 ± 3.98 mm preoperatively and decreased to 5.72 ± 1.68 mm immediately postoperatively but increased to 7.32 ± 2.29 mm at last follow-up (P = .07). Horizontal displacement of the distal clavicle was 1.1 ± 1.0 mm immediately postoperatively but decreased to 0.9 ± 0.6 mm at last follow-up (P < .05). In particular, in the 2 groups that were determined using the hierarchical cluster analysis, patients with excellent recovery of the initial CCD (20 patients) showed less of an increase in the CCD at last follow-up than did those in the other group (7 patients) (P < .001). The Constant-Murley score was 93.5 ± 2.7 points on the injured side at last follow-up (P = .074). CONCLUSIONS: Our CC fixation technique with multiple low-profile devices exhibited satisfactory clinical and radiologic outcomes. In particular, ensuring good initial recovery of the CCD and the precise placement and location of the AC joints was important in maintaining the proper AC position at the final follow-up. LEVEL OF EVIDENCE: Level IV, case series.

Analysis of impingement-free range of motion of the glenohumeral joint after reverse total shoulder arthroplasty using three different implant models.

BACKGROUND: This study aimed to investigate impingement-free range of motion (ROM) of the glenohumeral joint following reverse total shoulder arthroplasty (RTSA) with three types of implant models using computational motion analysis. METHODS: Three-dimensional (3D) scapulohumeral models were created from preoperative computed tomography (CT) images of seven patients by using visualization and computer-aided design software. Three types of implant designs, namely, typical medialization, in between, and lateralization implants, were used for the reconstruction of 3D model; each design was designated as group I, II, and III, respectively. All possible combinations of virtual surgeries were evaluated for impingement-free ROM in all three groups. Maximal ROMs were compared. The effect of implant positions on ROM of the shoulder joints were investigated in each group. RESULTS: The all lateralization group (group III) showed significantly greatest maximal adduction, abduction and external rotation (ER). Adduction and abduction were significantly increased by the glenoid component inferior translation in all three groups. (In group I, p < 0.001 for adduction, p = 0.002 for abduction, respectively; in group II, p = 0.025, p < 0.001, respectively; in group III, p = 0.038, p = 0.011, respectively). Increasing humerus retroversion might have some effect on increasing abduction. In group II and III, internal rotation (IR) and ER were significantly affected by the humerus retroversion (in group II, p = 0.033 for IR, p = 0.007 for ER, respectively; in group III, p = 0.004, p < 0.001, respectively). In group III, ER was also significantly affected by the glenoid component inferior translation (p = 0.003). CONCLUSIONS: Lateralization design model showed greatest ROM of the shoulder joint. The effects of implant positions on impingement-free ROM exhibited different tendencies between medialization and lateralization implant models. Humerus retroversion affected both IR and ER, especially in lateralization design. Increasing glenoid inferior translation increases both adduction and abduction regardless of implant designs.

Which Is Better for Arthroscopic Tenodesis of the Long Head of the Biceps: Soft Tissue or Bony Interference Fixation?

PURPOSE: To compare the outcome between arthroscopic soft tissue tenodesis (STT) at the rotator interval and bony interference fixation tenodesis (BIFT) at the distal bicipital groove for the long head of the biceps (LHB). METHODS: Twenty-five shoulders that underwent arthroscopic STT of the LHB were compared with 28 shoulders that underwent arthroscopic BIFT using a 5.5-mm Bio-Tenodesis screw (Arthrex, Naples, FL). American Shoulder and Elbow Surgeons scores, Constant score, and elbow flexion strength index (EFSI) were checked preoperatively, postoperative 1 year and 2 years. Ultrasound imaging evaluation took place at 1 year and 2 years postoperatively as well. RESULTS: The overall functional outcomes improved after surgery in both groups. The BIFT group showed a significant increase in EFSI (preop: 0.54, postoperative 2 years: 0.94) compared with that of the STT group (preop: 0.52, postoperative 2 years: 0.74) at postoperative 2 years (P = .006). However, no significant difference was seen in the increase of American Shoulder and Elbow Surgeons scores and Constant scores between the two groups. At postoperative 2 years, ultrasound showed seven empty grooves in the STT group, but only two empty grooves in the BIFT group (P = .046). CONCLUSIONS: Arthroscopic BIFT for the LHB showed better improvement in EFSI than arthroscopic STT. In addition, the STT group showed a higher failure rate than the BIFT group. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Shoulder Stiffness: Current Concepts and Concerns.

UNLABELLED: Shoulder stiffness can be caused by various etiologies such as immobilization, trauma, or surgical interventions. The Upper Extremity Committee of ISAKOS defined the term "frozen shoulder" as idiopathic stiff shoulder, that is, without a known cause. Secondary stiff shoulder is a term that should be used to describe shoulder stiffness with a known cause. The pathophysiology of frozen shoulder is capsular fibrosis and inflammation with chondrogenesis, but the cause is still unknown. Conservative treatment is the primary choice. Pain control by oral medication, intra-articular injections with or without joint distension, and physical therapy are commonly used. In cases with refractory stiffness, manipulation under anesthesia or arthroscopic capsular release may be indicated. Because of various potential risks of complications with manipulations, arthroscopic capsular release is preferred. After the capsular release, stepwise rehabilitation is mandatory to achieve satisfactory outcome. LEVEL OF EVIDENCE: Level V, evidence-based review.

Locked bucket-handle type bony Bankart lesion resulting from manipulation.

A patient who underwent manipulation for stiffness accompanying a rotator cuff tear experienced a complication consisting of a bony Bankart lesion connected to the superior and inferior labrum. This lesion was displaced posteriorly, locked behind the humeral head and blocking the reduction. Attachment of the labrum to this fragment made reduction and fixation easier. This bony Bankart lesion was fixed successfully by arthroscopic placement of knotless suture anchors. Level of evidence Case report, Level IV.

Stress Distribution in Superior Labral Complex and Rotator Cuff During In Vivo Shoulder Motion: A Finite Element Analysis.

PURPOSE: To quantitatively and qualitatively evaluate the impingement behavior between structures within the glenohumeral joint under simulated abduction-external rotation (ABER) motion using finite element analysis. METHODS: Computed tomography (CT) scanning of 1 shoulder in a volunteer was performed at 0° and 120° of shoulder abduction with external rotation (ABER position), followed by magnetic resonance imaging at 0° of abduction. The CT and magnetic resonance images were then imported into a customized software program to undergo 3-dimensional reconstruction followed by finite element modeling of the bone and soft tissue including the upper part of the rotator cuff and glenohumeral labral complex. Glenohumeral motion from 0° to the ABER position was simulated by CT images in 2 different humeral positions. On the basis of simulated humeral motion with respect to the scapula, we measured the stress value on the biceps-labral complex and upper part of the rotator cuff as a consequence of their structural deformation. In addition, we intended to design 2 types of labra--a normal stable labrum and an unstable posterosuperior labrum--to evaluate the geometric alteration and resulting stress change on the posterosuperior labrum against a compressive force from the humeral head and rotator cuff. RESULTS: In the ABER position, the posterosuperior labrum was deformed by the humeral head and interposed posterior part of the rotator cuff. When viewed from the rotator cuff, the posterior part of the rotator cuff came into contact with the posterosuperior labrum as external rotation increased. The measured peak contact stress values were 19.7 MPa and 23.5 MPa for the posterosuperior labrum and the upper rotator cuff, respectively. The stress values for both structures decreased to 5.8 MPa and 18.1 MPa, respectively, in the simulated SLAP model. The root of the long head of the biceps became compressed halfway through the range of motion by the humeral head, especially from the part involving horizontal extension and external rotation, resulting in a high stress of 22.4 MPa. CONCLUSIONS: In this simulated SLAP model, the posterosuperior labrum was medially displaced by the humeral head and upper rotator cuff in the ABER position, causing a functional loss of the spacer effect. CLINICAL RELEVANCE: In SLAP lesions, the posterosuperior labrum loses its ability to function as a spacer in certain positions (especially ABER) and may decrease the important spacer effect between the humerus and the rotator cuff; this may lead to posterosuperior subluxation of the humeral head or rotator cuff abnormalities and tears during repetitive ABER tasks.

Efficacy of direct arthroscopy-guided suprascapular nerve block after arthroscopic rotator cuff repair: a prospective randomized study.

PURPOSE: The purpose of this study was to evaluate the outcomes of arthroscopy-guided direct suprascapular nerve block performed after arthroscopic rotator cuff repair. METHODS: In the present prospective, randomized, double-blinded clinical study, 30 patients were divided into two groups: 15 patients (group I) were treated with arthroscopy-guided suprascapular nerve block using 10 mL 0.5 % ropivacaine with 1:200,000 epinephrine, and 15 patients (group II) were treated with placebo using 10 mL 0.9 % saline after arthroscopic rotator cuff repair. Patient pain levels were measured using the visual analog scale (VAS) at 1, 3, 6, 12, 18, and 24 h post-operatively. Additionally, the number of boluses and total amount of fentanyl dispensed by patient-controlled analgesia administration during the 24-h post-operative period were evaluated. RESULTS: VAS scores did not differ significantly between groups I and II during the 24-h post-operative period, but mean fentanyl bolus consumption was significantly less in group I compared with group II (p = 0.015). CONCLUSION: Arthroscopy-guided suprascapular nerve block at the end of a rotator cuff repair was safe and less time-consuming than expected. Although this procedure did not significantly reduce the post-operative pain, the post-operative need for fentanyl boluses as analgesia was reduced significantly, and it would be beneficial if this procedure involved a sensory branch of axillary nerve block or was performed at the beginning of the arthroscopic procedure. LEVEL OF EVIDENCE: Prospective, randomized, double-blinded clinical trial, Level I.

In vivo analysis of acromioclavicular joint motion after hook plate fixation using three-dimensional computed tomography.

BACKGROUND: The clavicle hook plate can be used to treat acromioclavicular and coracoclavicular ligament injury or distal clavicular fracture with comminution. However, the hook plate can induce subacromial impingement, resulting in discomfort from the hardware. METHODS: Our inclusion criteria were (1) men and women aged older than 20 years and (2) the presence of comminuted distal clavicular fractures (Neer type IIB) fixed with a hook plate (Synthes, Oberdorf, Switzerland). Three-dimensional computed tomography was obtained before removal of the hook plate. Seven patients were enrolled prospectively. The mean age was 42 years (range, 24-60 years). Zero degree images and abduction images were obtained. The sagittal cut surface was obtained 5 mm medial from the distal clavicle. The equator of the cut surface of the clavicle was compared with the full abduction model to analyze rotation. The center of the cut surface of the clavicle was compared with the full abduction model to analyze translation. RESULTS: The average difference in rotation of the distal clavicle between both shoulders was 16° (range, 3°-22°; P = .001). The mean difference in anterior translation of the distal clavicle was 2.2 mm (range, -0.7 to 5.6 mm; P = .030). CONCLUSION: Hook plate fixation at the acromioclavicular joint causes decreased internal rotation and increased anterior translation of the distal clavicle with respect to the medial acromion, indicating that the scapula relative to the thorax has decreased posterior tilting and increased external rotation in shoulders fixed using a hook plate.

The effect of notchplasty on tunnel widening in anterior cruciate ligament reconstruction.

PURPOSE: To investigate changes in femoral tunnel diameter, dimension, and volume after anterior cruciate ligament reconstruction with notchplasty. METHODS: Porcine knee specimens were divided into 2 groups of 10 specimens each. Group A did not receive notchplasty. A 2-mm notchplasty was conducted in group B. Seven-millimeter-diameter femoral tunnels were drilled and a doubled flexor digitorum profundus tendon was inserted and fixed with an EndoButton (Smith & Nephew, Andover, MA) in each knee specimen. Samples were mounted on a materials testing machine. Each group was preloaded at 10 N and subjected to 20 loading cycles (between 0 and 40 N), followed by 1,000 loading cycles in the elastic region (between 10 and 150 N). High-resolution computed tomography with 1.0-mm slices was conducted with all samples before and after testing. A 3-dimensional model was constructed to evaluate the degree of the tunnel change. RESULTS: In group B the mean longest diameter and dimension of the femoral tunnel significantly increased after the test (P = .005 and P = .001, respectively). The volumetric loss of bony structure after the test in group B was significantly greater than that in group A (P = .039). Meanwhile, no significant difference was found before and after the test in terms of tunnel diameter, dimension, and volumetric loss around the tunnel in group A. CONCLUSIONS: The intra-articular orifice of the femoral tunnel was enlarged after the uniaxial cyclic loading test after notchplasty. An enlarged tunnel orifice may lead to a discrepancy between the tunnel and the graft at the tunnel aperture. CLINICAL RELEVANCE: The data may have an implication that suspensory fixation with a notchplasty has a negative effect on the full graft accommodation at the tunnel aperture. Aperture widening may affect graft positioning, leading to subtle changes in graft biomechanics and laxity.

Graft tension of the posterior cruciate ligament using a finite element model.

PURPOSE: The aim of the study was to analyse the change in length and tension of the reconstructed single-bundle posterior cruciate ligament (PCL) with three different femoral tunnels at different knee flexion angles by use of three-dimensional finite element method. METHODS: The right knees of 12 male subjects were scanned with a high-resolution computed tomography scanner at four different knee flexion angles (0°, 45°, 90° and 135°). Three types of single-bundle PCL reconstruction were then conducted in a 90° flexion model: femoral tunnels were created in anterolateral (AL), central and posteromedial (PM) regions of the footprint. Length versus flexion curves and tension versus flexion curves were generated. RESULTS: Between 0° and 90° of knee flexion, changes in length and tension in the PM grafts were not significant. Whereas the lengths and tension of the AL and central grafts significantly increased in the same flexion range. The length and tension of the PM grafts at 135° of knee flexion were significantly higher than those at 90° of knee flexion, whereas the AL and the central grafts showed only slight length changes beyond 90° of flexion. However, the tension of the AL graft increased significantly beyond 90° of flexion. CONCLUSIONS: Changes in the graft length, and tension were generally affected by different femoral tunnels and knee flexion angles. In groups with the AL and PM single-bundle reconstruction, the graft tension increased beyond 90° of knee flexion when the graft is tensioned at 90° of flexion. These data suggest that final fixation angle at 90° for the AL or PM graft would induce graft overtension in high knee flexion of 135°. Whereas central graft which is fixed in 90° of flexion is desirable in terms of prevention of graft overtension. Because the graft tension within it was relatively constant beyond 90° of flexion.

Computed tomographic image analysis based on FEM performance comparison of segmentation on knee joint reconstruction.

The demand for an accurate and accessible image segmentation to generate 3D models from CT scan data has been increasing as such models are required in many areas of orthopedics. In this paper, to find the optimal image segmentation to create a 3D model of the knee CT data, we compared and validated segmentation algorithms based on both objective comparisons and finite element (FE) analysis. For comparison purposes, we used 1 model reconstructed in accordance with the instructions of a clinical professional and 3 models reconstructed using image processing algorithms (Sobel operator, Laplacian of Gaussian operator, and Canny edge detection). Comparison was performed by inspecting intermodel morphological deviations with the iterative closest point (ICP) algorithm, and FE analysis was performed to examine the effects of the segmentation algorithm on the results of the knee joint movement analysis.

Teres minor denervation and pathologies resulting in shoulder joint instability and rotator cuff tears: A retrospective cross-sectional MRI study.

Teres minor denervation (TMD) has gained increasing attention in recent years, particularly with the advent of magnetic resonance imaging (MRI). The potential association between TMD and shoulder instability or rotator cuff tear remains a subject of interest in the orthopedic community. In this retrospective and cross-sectional study, authors aim to investigate the potential association between TMD and shoulder instability or rotator cuff tears. Authors retrospectively analyzed MRI findings from 105 patients with TMD, focusing on rotator cuff pathologies, posterior labrocapsular complex (PLCC) tears, and posteroinferior glenohumeral joint capsule alterations. Authors assessed the association between TMD and rotator cuff and PLCC tears. For the multivariate analysis, partial proportional odds models were constructed for subscapularis (SSC) and SSP tears. Rotator cuff tears were present in 82.9% of subjects, with subscapularis (SSC) tears being the most frequent (77.1%). A significant association was observed between TMD and rotator cuff pathology (P = .002). PLCC tears were found in 82.3% of patients, and humeral position relative to the osseous glenoid was noted in 60% of patients with TMD. A significant association was identified between TMD and shoulder instability or labral/capsular abnormalities (P < .001). More than half of the cases exhibited a long tethering appearance toward the axillary neurovascular bundle on T1-weighted sagittal images. Our findings suggest that TMD is significantly associated with rotator cuff tears and shoulder instability. This study highlights the importance of identifying and treating PLCC tears in patients with TMD to address shoulder instability. Further research is needed to elucidate the role of TMD in the pathogenesis of shoulder instability and rotator cuff pathology.

Arthroscopic double row partial articular supraspinatus tendon avulsion bridge repair technique for shoulder: A transtendinous approach.

Partial articular supraspinatus tendon avulsion (PASTA) lesions, a subset of partial rotator cuff tears, pose a surgical challenge, disrupting the integrity of the supraspinatus tendon. Transtendinous repair is the preferred choice in young individuals for limiting tear progression and preserving intact, high-quality cuff tissue, thus preventing tendon shortening, as compared to the tear completion and repair technique. Our approach leverages these advantages, specifically those indicated for Ellman's Grade 3 tears and cases where conservative treatments have failed. In our technique, we employ progressive dilation, anchor drill sleeve insertion to facilitate medial row anchor placement, followed by percutaneous spinal needles for suture shuttling, and finally locking sliding knots for compressive medial row repair, followed by lateral row fixation for additional stability. This method accelerates rehabilitation and restores optimal shoulder function.

Management of disorders of the rotator cuff: proceedings of the ISAKOS upper extremity committee consensus meeting.

The goal of this article is to consolidate the International Society of Arthroscopy, Knee Surgery & Orthopaedic Sports Medicine (ISAKOS) Upper Extremity Committee's (UEC's) current knowledge on rotator cuff disease and management, as well as highlight key unresolved issues. The rotator cuff is an anatomically complex structure important for providing glenohumeral function and stability as part of a closed chain system. Current consensus suggests rotator cuff injuries are most accurately diagnosed, at levels similar to diagnosis by magnetic resonance imaging, with a combination of cuff- and impingement-specific clinical tests. Updates in the understanding of acromion morphology, the insertional anatomy of the rotator cuff, and the role of suprascapular nerve release may require changes to current classification systems and surgical strategies. Although initial management focuses on nonoperative protocols, discussion continues on whether surgery for isolated impingement is clinically more beneficial than rehabilitation. However, clear indications have yet to be established for the use of single- versus double-row repair because evidence confirms neither is clinically efficacious than the other. Biceps tenodesis, however, in non-isolated cuff tears has proven more successful in addressing the etiology of shoulder pain and yields improved outcomes over tenotomy. Data reviewing the benefits of tendon transfers, shoulder prostheses, and mechanical scaffolds, as well as new research on the potential benefit of platelet-rich plasma, pluripotential stem cells, and gene therapies, will also be presented.

Arthroscopic Subscapularis Tendon Repair Using the Lasso-Loop Technique Through Anterolateral Viewing Portal.

The subscapularis is the strongest muscle among the rotator cuff muscles, and it provides a coupled balanced force across the glenohumeral joint by resisting the infraspinatus in axial plane and the shearing force of deltoid in the coronal plane. It is important to repair subscapularis tears to maintain the coupled balanced force. Subscapularis tendon tears are difficult to diagnose and treat. Only a small portion of the subscapularis tendon is visualized during routine arthroscopy, as it is largely covered by the middle and inferior glenohumeral ligaments. Various repair techniques have been described in the literature. Here, we describe the anterolateral viewing portal for better visualization of subscapularis and our preferred technique, the lasso-loop technique, which provides better tissue grip and improved functional outcome.

Dynamic function of coracoclavicular ligament at different shoulder abduction angles: a study using a 3-dimensional finite element model.

PURPOSE: The aim of this study was to determine the acromioclavicular (AC) motion and change in length and tension of the coracoclavicular ligament during different positions of shoulder abduction using a 3-dimensional finite element model based on computed tomography images from normal human shoulders. METHODS: The right shoulders of 10 living subjects were scanned with a high-resolution computed tomography scanner at 0°, 60°, 120°, and 180° of shoulder abduction. Several modeling programs were used to simulate AC motion. Finite element models of the conoid and trapezoid ligaments were constructed based on each footprint. The tension and length changes of each ligament during shoulder abduction were assessed. RESULTS: The distal clavicle exhibited internal rotation with respect to the medial acromion at 0°, 60°, 120°, and full abduction (3.2° ± 2.9°, 23.2° ± 10.8°, 20.6° ± 3.7°, and 37.1° ± 3.4°, respectively). With horizontal motion, the clavicle translated posteriorly at 60° of abduction (4.4 ± 3.4 mm) and then translated anteriorly at 120° and full abduction (0.4 ± 1.6 mm and 1.9 ± 0.4 mm, respectively). The lengths of the conoid ligament gradually increased at 60° to 180° of shoulder abduction whereas those of the trapezoid ligament remained relatively consistent at 60° to 120° of abduction compared with 0° of abduction. CONCLUSIONS: The distal clavicle had a wide range of motion during shoulder abduction, which did not support the concept of synchronous motion with the scapula. The conoid and trapezoid ligaments functioned reciprocally during shoulder abduction. With increasing shoulder abduction, the length of the conoid ligament gradually increased; meanwhile, the trapezoid ligament was relatively consistent and then lax at full abduction. In particular, the conoid ligament may act as a key restraint to prevent excessive retraction of the scapula during shoulder abduction. CLINICAL RELEVANCE: The data in this study have the potential to suggest that conoid and trapezoid ligaments should be reconstructed separately, and rigid AC fixation in patients with AC separation is not recommended based on the findings of this study.

Symptomatic residual instability with grade II acromioclavicular injury.

PURPOSE: Our objective was to evaluate the effectiveness of arthroscopic distal clavicle resection in cases presenting with pain and subtle instability after neglected grade II acromioclavicular (AC) joint dislocation. METHODS: From February 1998 to May 2006, 17 patients with symptomatic AC instability following chronic grade II AC joint injury were studied. Sixteen patients were male and one female, with a mean age of 48 years. An all-arthroscopic procedure comprising disk removal and distal clavicle resection was performed in all cases. All patients were reviewed clinically, preoperatively and at final follow-up (mean 38 months) using the pain score on a visual analog scale and the Constant score. Strength was measured using an Isobex digital strength analyzer. Patient's personal satisfaction after the procedure was documented as excellent, good or poor. Postoperative AC joint radiographs were routinely obtained in all patients to measure the amount of clavicle resection. RESULTS: Two patients underwent additional reconstructive surgery for disabling pain and dysfunction even after the arthroscopic resection procedure. The remaining 15 patients were analyzed. The pain scores improved significantly (p = 0.03). The mean pain score was 5.8 (range 5-9) before treatment and 1.6 (range 0-3) at follow-up. The Constant scores had improved significantly at the final follow-up (p = 0.001). The median Constant score increased from 46 (range 36-69) preoperatively to 71 (range 48-84) postoperatively. Strength had improved at the last follow-up. Eleven patients were satisfied and six were not satisfied with this procedure at the final follow-up. CONCLUSIONS: Arthroscopic distal clavicle resection statistically improved the pain score, Constant score and strength for grade II AC injury with subtle distal clavicle instability. However, six patients (33.5 %) were not satisfied subjectively. This procedure seemed to be a reasonable initial treatment option with lower morbidity.

Does the Suprascapular Nerve Move within the Suprascapular Notch? Biomechanical Perspective Using the Finite Element Method.

PURPOSE: We aimed to analyze changes in suprascapular nerve (SSN) position within the suprascapular notch during in vivo shoulder abduction. MATERIALS AND METHODS: Three-dimensional models of the shoulder complex were constructed based on magnetic resonance imaging of the brachial plexus (BP-MR) in a patient diagnosed with SSN dysfunction but normal scapular movement. Using BP-MR in neutral position and computed tomography data on shoulder abduction, shoulder abduction was simulated as the transition between two positions of the shoulder complex with overlapping of a neutral and abducted scapula. SSN movement during abduction was evaluated using the finite element method. Contact stress on the SSN was measured in the presence and absence of the transverse scapular ligament (TSL). RESULTS: In the neutral position, the SSN ran almost parallel to the front of the TSL until entering the suprascapular notch and slightly contacted the anterior-inferior border of the TSL. As shoulder abduction progressed, contact stress decreased due to gradual loss of contact with the TSL. In the TSL-free scapula, there was no contact stress on the SSN in the neutral position. Towards the end of shoulder abduction, contact stress increased again as the SSN began to contact the base of the suprascapular notch in both TSL conditions. CONCLUSION: We identified changes in the position of the SSN path within the suprascapular notch during shoulder abduction. The SSN starts in contact with the TSL and moves toward the base of the suprascapular notch with secondary contact. These findings may provide rationale for TSL release in SSN entrapment.