Wei-Ren Su

The Effect of Anterosuperior Rotator Cuff Tears on Glenohumeral Translation

PURPOSE The purpose of this study was to sequentially investigate the biomechanical effects of anterosuperior rotator cuff tear size on superior and anterosuperior translation, including tears interrupting the anterior cable attachment and the anterior force couple. METHODS Five cadaveric shoulders were subjected to different loading conditions in both the superior and anterosuperior directions in the intact state, with the supraspinatus cut and with sequentially larger anterosuperior rotator cuff tears. RESULTS Isolated tears of the supraspinatus had no significant biomechanical consequences under any condition tested. Anterosuperior translation was greater than superior translation in the intact specimen and for every combination of anterosuperior rotator cuff defect. With the supraspinatus and the superior half of the subscapularis (i.e., the anterior cable attachment) released, there was no significant increase in anterosuperior or superior glenohumeral translation in response to lower loading conditions (10 to 20 N). At higher loading conditions (40 to 50 N), tears of the supraspinatus and superior half of the subscapularis led to significantly increased translation in both directions. CONCLUSIONS Simulated anterosuperior rotator cuff tears involving the superior half of the subscapularis significantly alter shoulder biomechanics and lead to increased anterosuperior and superior glenohumeral translation under higher loads. The anterior attachment of the rotator cuff cable is therefore an important determinant of the biomechanics of anterosuperior rotator cuff tears at higher loads but not at lower loads. Preserving the inferior half of the subscapularis was sufficient to maintain relatively normal shoulder kinematics under lower loading conditions. Tears of the entire subscapularis altered glenohumeral kinematics at essentially all loads. CLINICAL RELEVANCE Knowledge of the biomechanics of anterosuperior rotator cuff tears enhances our understanding of how to best treat these lesions.

The Effect of Coracoacromial Ligament Excision and Acromioplasty on Superior and Anterosuperior Glenohumeral Stability

PURPOSE To determine the effect of coracoacromial ligament (CAL) resection and subacromial decompression (SAD)/acromioplasty on humeral head translation under anterosuperior and superior loading in a cadaveric model with an intact rotator cuff. METHODS Six cadaveric shoulders were tested in the intact state, following CAL resection and following SAD. RESULTS Excision of the CAL led to a significant increase in anterosuperior humeral translation of 2.1 mm (17%). SAD led to a significant increase in superior humeral translation of 2.5 mm (28%). CONCLUSIONS The results of this cadaveric study showed that resection of the CAL led to a 2.1-mm increase in anterosuperior translation and that SAD led to a 2.5-mm increase in superior translation. CLINICAL RELEVANCE CAL resection and SAD are common surgical procedures, which may lead to increases in anterosuperior and superior glenohumeral instability.

The effect of posterosuperior rotator cuff tears and biceps loading on glenohumeral translation.

PURPOSE To investigate the biomechanical effects of posterosuperior rotator cuff tear (RCT) size and of loading the long biceps tendon in the presence of various-sized RCTs. METHODS Ten cadaveric shoulders were subjected to loading in the superior and anterosuperior directions in the intact state and with sequentially larger RCTs. Glenohumeral translation was measured with and without biceps tendon loading. RESULTS As long as the inferior infraspinatus remained intact, there was no significant difference in glenohumeral translation for any load studied. Once the supraspinatus and the entire infraspinatus were released, 50 N of load led to significantly increased translation in both directions. When we compare the results of this study with those of a previous study, the subscapularis appears to be more effective than the infraspinatus in constraining both anterosuperior and superior translation. For the intact specimens and for all sizes of RCTs, biceps loading led to a significant decrease in both anterosuperior and superior glenohumeral translation. Depending on the size of the RCT and the direction of loading, this decrease in glenohumeral translation varied from 19% to 53%. CONCLUSIONS Tears of the subscapularis have greater biomechanical consequences than do tears of the infraspinatus. Loading the long biceps tendon led to a significant decrease in anterosuperior and superior glenohumeral translation for all sizes of RCTs, with a greater decrease in the percentage of glenohumeral translation noted for larger tears. CLINICAL RELEVANCE Knowledge of the biomechanics of posterosuperior RCTs enhances our ability to treat them. Surgeons should be aware that, although biceps tenotomy or tenodesis may provide pain relief in shoulders with RCTs, there are biomechanical consequences to these procedures.

A simple modified arthroscopic suture fixation of avulsion fracture of the tibial intercondylar eminence in children

The purpose of this study was to describe a simple and modified technique for arthroscopic suture fixation in a 12-year-old boy who sustained a displaced type III intercondylar eminence of the tibial. The arthroscopic fixation was modified by using the Arthrex suture lasso device to place two nonabsorbable sutures into the anterior cruciate ligament (ACL). However, the procedure became simple with the help of the Acufex ACL guide to reduce the avulsed tibial spine fragment and to place an appropriate tibial tunnel. Sutures were then passed through the tibial tunnel and secured over a bony bridge with the knee at 20° of flexion. At 6 months, the patient had a full range of motion with normal Lachman and anterior drawer testing, and he had returned to his daily activities. Radiographs showed complete fracture healing. Repair using the Arthrex suture lasso device provides a significant advantage in the treatment of type III and IV fractures of the tibial eminence by obtaining arthroscopic fixation with the substance of the ACL, thus eliminating the risks of comminution of the fracture fragment and hardware removal. This arthroscopic technique restores the length and integrity of the ACL, and provides a simplified, reproducible method of treatment for this injury.

Treatment of unstable distal clavicle fractures with Knowles pin

BACKGROUND Unstable distal clavicle fractures often need surgical treatment. This report describes a new intramedullary extra-articular Knowles pin fixation method to treat these unstable fractures. MATERIALS AND METHODS Twelve patients with unstable distal clavicle fractures (Neer type II) had surgery with intramedullary extra-articular Knowles pin fixation. We retrospectively reviewed clinical results for pain, shoulder function, and range of motion, as well as radiographic results, for this institutional review board-approved study. Each patients operated arm was in a sling for 4 weeks postoperatively. The University of California, Los Angeles shoulder rating scale score was used to evaluate shoulder function. RESULTS All patients showed radiographically confirmed bony union. The mean period required for healing was 11.5 weeks, and patients were followed up for 6 to 24 months (mean, 15.2 months), during which University of California, Los Angeles scores (mean, 33.9) indicated good clinical results. Three patients had the complication of proximal or distal skin irritation caused by the thread and hub of the Knowles pin. CONCLUSIONS The Knowles pin fixation method is useful for treating unstable distal clavicle fractures. However, sufficient familiarity with the technique and careful preoperative planning to determine the appropriate length of the pin are necessary to prevent complications and to effect a high union rate.

Clinical and Ultrasonographic Results of Ultrasonographically Guided Percutaneous Radiofrequency Lesioning in the Treatment of Recalcitrant Lateral Epicondylitis

Background: In patients with lateral epicondylitis recalcitrant to nonsurgical treatments, surgical intervention is considered. Despite the numerous therapies reported, the current trend of treatment places particular emphasis on minimally invasive techniques. Purpose: The authors present a newly developed minimally invasive procedure, ultrasonographically guided percutaneous radiofrequency thermal lesioning (RTL), and its clinical efficacy in treating recalcitrant lateral epicondylitis. Study Design: Case series: Level of evidence, 4. Methods: Thirty-four patients (35 elbows), with a mean age of 52.1 years (range, 35-65 years), suffered from symptomatic lateral epicondylitis for more than 6 months and had exhausted nonoperative therapies. They were treated with ultrasonographically guided RTL. Patients were followed up at least 6 months by physical examination and 12 months by interview. The intensity of pain was recorded with a visual analog scale (VAS) score. The functional outcome was evaluated using grip strength, the upper limb Disability of Arm, Shoulder and Hand (QuickDASH) outcome measure, and the Modified Mayo Clinic Performance Index (MMCPI) for the elbow. The ultrasonographic findings regarding the extensor tendon origin were recorded, as were the complications. Results: At the time of the 6-month follow-up, the average VAS score in resting (from 4.9 to 0.9), palpation (from 7.6 to 2.5), and grip (from 8.2 to 2.9) had improved significantly compared with the preoperative condition (P < .01). The grip strength (from 20.6 to 27.0 kg) and QuickDASH score (from 54.3 to 21.0) had also improved significantly (P < .01). The MMCPI score improved from “poor” to “excellent.” The ultrasonographic finding revealed that the thickness of the common extensor tendon origin did not change significantly. At the final follow-up (mean, 14.3 months; range, 12-21 months), the patients reported a 78% reduction in pain compared with the preoperative status. No major complications were noted in any patient. Conclusion: Ultrasonographically guided RTL for recalcitrant lateral epicondylitis was found to be a minimally invasive treatment with satisfactory results in this pilot investigation. This innovative method can be considered as an alternative treatment of recalcitrant lateral epicondylitis before further surgical intervention.

Compression of the radial nerve at the elbow by a ganglion: two case reports.

IntroductionRadial nerve compression by a ganglion in the radial tunnel is not common. Compressive neuropathies of the radial nerve in the radial tunnel can occur anywhere along the course of the nerve and may lead to various clinical manifestations, depending on which branch is involved. We present two unusual cases of ganglions located in the radial tunnel and requiring surgical excision.Case presentationA 31-year-old woman complained of difficulty in fully extending her fingers at the metacarpophalangeal joint for 2 weeks. Before her first visit, she had noticed a swelling and pain in her right elbow over the anterolateral forearm. The extension muscle power of the metacarpophalangeal joints at the fingers and the interphalangeal joint at the thumb had decreased. Sonography and magnetic resonance imaging of the elbow revealed a cystic lesion located at the area of the arcade of Frohse. A thin-walled ovoid cyst was found against the posterior interosseous nerve during surgical excision. Pathological examination was compatible with a ganglion cyst. The second case involved a 36-year-old woman complaining of numbness over the radial aspect of her hand and wrist, but without swelling or tumor in this area. The patient had slightly decreased sensitivity in the distribution of the sensory branch of the radial nerve. There was no muscle weakness on extension of the fingers and wrist. Surgical exposure defined a ganglion cyst in the shoulder of the division of the radial nerve into its superficial sensory and posterior interosseous components. There has been no disease recurrence after following both patients for 2 years.ConclusionCompression of nerves by extraneural soft tissue tumors of the extremities should be considered when a patient presents with progressive weakness or sensory changes in an extremity. Surgical excision should be promptly performed to ensure optimal recovery from the nerve palsy.

Suture anchor versus screw fixation for greater tuberosity fractures of the humerus—a biomechanical study

Suture anchors and screws are commonly used for fixation of humeral greater tuberosity (GT) fractures in either arthroscopic or open surgeries, but no biomechanical studies have been performed to compare the strength of fixation constructs using these two implants. This cadaveric study aimed to compare the biomechanical strength of three different fixation constructs in the management of GT fractures: Double‐Row Suture Anchor Fixation (DR); Suture‐Bridge Technique using suture anchors and knotless suture anchors (SB); and Two‐Screw Fixation (TS). The experimental procedure was designed to assess fracture displacement after cyclic loading, failure load, and failure mode of the fixation construct. Significant differences were found among the SB (321 N), DR (263 N), and TS (187 N) groups (SB > DR > TS, p < 0.05) in the mean force of cyclic loading to create 3 mm displacement. Regarding the mean force of cyclic loading to create 5 mm displacement and ultimate failure load, no significant difference was found between the DR (370 N, 480 N) and SB (399 N, 493 N) groups, but both groups achieved superior results compared with the TS group (249 N, 340 N) (p < 0.05). The results suggested that the suture anchor constructs would be stronger than the fixation construct using screws for the humeral GT fracture.

The modified finger-trap suture technique: A biomechanical comparison of a novel suture technique for graft fixation

PURPOSE The purpose of this study was to compare the tendon graft holding power of the newly devised modified finger-trap (MFT) suture technique with other currently used sutures. METHODS We used 40 fresh-frozen porcine flexor profundus tendons randomly divided into 4 groups of 10 specimens. The experimental procedure was designed to assess percent elongation of the suture-tendon construct across four different tendon-grasping techniques: MFT suture, Krackow stitch, locking SpeedWhip stitch (Arthrex, Naples, FL), and nonlocking SpeedWhip stitch. The suture configurations of the MFT suture and Krackow stitch were completed with a No. 2 FiberWire suture (Arthrex). The locking SpeedWhip and nonlocking SpeedWhip stitches were completed with a loop of No. 2 FiberWire suture and a FiberLoop needle (Arthrex). Each tendon was pre-tensioned to 100 N for three cycles and then cyclically loaded to 200 N for 200 cycles. Finally, each tendon was loaded to failure. Percent elongation, load to failure, and mode of failure for each suture-tendon construct were measured. RESULTS During the pre-tension phase, the MFT suture had the smallest percent elongation (P = .021) of the suture-graft construct (13.5% ± 1.9%) compared with the Krackow (16.9% ± 1.2%), locking SpeedWhip (17.6% ± 0.6%), and nonlocking SpeedWhip (33.3% ± 5.6%) stitches. During cyclic loading, the MFT suture also showed a significantly smaller percent elongation (P = .037) of the suture-graft construct (27.8% ± 4.9%) than the Krackow (35.8% ± 5.4%), locking SpeedWhip (33.7% ± 5.4%), and nonlocking SpeedWhip (43.8% ± 7.8%) stitches. The load to failure and cross-sectional area were not significantly different across all the suture groups. CONCLUSIONS The newly devised MFT suture provided better percent elongation and equal load to failure compared with the Krackow and SpeedWhip suture techniques tested in this in vitro biomechanical evaluation. CLINICAL RELEVANCE The MFT suture is a simple method that is an attractive alternative to the Krackow and SpeedWhip suture techniques for tendon graft fixation in ligament reconstruction.

Biomechanical Study Comparing Biceps Wedge Tenodesis With Other Proximal Long Head of the Biceps Tenodesis Techniques

PURPOSE The purpose of this biomechanical study was to compare the ultimate failure strength, stiffness, cyclic displacement, and failure displacement of 5 different proximal biceps tenodesis fixation techniques, specifically comparing wedge tenodesis with the other 4 techniques. METHODS Forty cadaveric shoulders underwent 1 of 5 long head of the biceps tenodesis techniques and were cyclically tested to failure by use of tensile forces applied parallel to the longitudinal axis of the humerus. A preload at 5 N was applied for 2 minutes, followed by cyclical loading for 500 cycles from 5 to 70 N at 1 Hz and a pull-to-failure test at 1 mm/s. The techniques studied were wedge tenodesis, suture anchor fixation, suprapectoral interference screw fixation, T-wedge tenodesis, and the percutaneous intra-articular transtendon (PITT) technique. Cyclic displacement, failure displacement, and stiffness were calculated. RESULTS The wedge tenodesis technique had an ultimate failure load similar to interference screw fixation and a greater ultimate failure load and stiffness than the suture anchor, PITT, and T-wedge techniques (P < .05). CONCLUSIONS In this biomechanical study, wedge tenodesis was found to have an ultimate failure load similar to interference screw fixation and a greater ultimate failure load and stiffness than the suture anchor, PITT, and T-wedge techniques. CLINICAL RELEVANCE On biomechanical testing, wedge tenodesis compares favorably with other techniques and may be a useful clinical option for proximal biceps tenodesis.