Biomechanical evaluation of the origin of the long head of the biceps tendon

Free Reverse Gracilis Muscle Combined With Steindler Flexorplasty for Elbow Flexion Reconstruction After Failed Primary Repair of Extended Upper-Type Paralysis of the Brachial Plexus

PURPOSE

To report the clinical outcomes of elbow flexion reconstruction using a reverse free gracilis muscle flap plus Steindler flexorplasty in patients with previously failed reconstruction of extended upper-type brachial plexus paralysis.

METHODS

Twenty-four male patients were reoperated upon an average of 45 months (SD, ± 45 months) after brachial plexus repair. The gracilis tendon was secured to the acromion, and the muscle belly was sutured to the biceps distal tendon. Vascular repair was performed preferentially end to end to the radial artery and cephalic vein. Nerve repair was achieved by coapting the nerve to the gracilis to motor fascicles of the median or ulnar nerve. The medial epicondyle was osteotomized, proximally advanced by 4 to 5 cm and secured to the anterior side of the humerus.

RESULTS

Active elbow flexion was restored in 23 of 24 patients. Sixteen patients ultimately achieved M4 strength, among whom 6 had full range of motion (ROM), and the remaining 10 recovered an average of 110° (95% confidence interval [95% CI], 100°-120°) of elbow flexion. Seven patients exhibited M3 elbow flexion strength recovery, which was associated with weaker hands and incomplete ROM, averaging 94° (95% CI, 86°-102°). There was, on average, a 10° (95% CI, 4.4°-15.6°). elbow flexion contracture. Among the 16 patients with M4 level recovery of elbow flexion, supination was partially restored in 12.

CONCLUSIONS

In patients previously operated upon, using a reversed free gracilis muscle flap in association with a Steindler procedure is effective as salvage surgery to restore elbow flexion and partial supination.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Shoulder labral pathomechanics with rotator cuff tears

Rotator cuff tears (RCTs), the most common injury of the shoulder, are often accompanied by tears in the superior glenoid labrum. We evaluated whether superior humeral head (HH) motion secondary to RCTs and loading of the long head of the biceps tendon (LHBT) are implicated in the development of this associated superior labral pathology. Additionally, we determined the efficacy of a finite element model (FEM) for predicting the mechanics of the labrum. The HH was oriented at 30° of glenohumeral abduction and neutral rotation with 50N compressive force. Loads of 0N or 22N were applied to the LHBT. The HH was translated superiorly by 5mm to simulate superior instability caused by RCTs. Superior displacement of the labrum was affected by translation of the HH (P<0.0001), position along the labrum (P<0.0001), and interaction between the location on the labrum and LHBT tension (P<0.05). The displacements predicted by the FEM were compared with mechanical tests from 6 cadaveric specimens and all were within 1 SD of the mean. A hyperelastic constitutive law for the labrum was a better predictor of labral behavior than the elastic law and insensitive to ±1 SD variations in material properties. Peak strains were observed at the glenoid-labrum interface below the LHBT attachment consistent with the common location of labral pathology. These results suggest that pathomechanics of the shoulder secondary to RCTs (e.g., superior HH translation) and LHBT loading play significant roles in the pathologic changes seen in the superior labrum.

Arthroscopic anatomy, variants, and pathologic findings in shoulder instability

Shoulder instability is a common diagnosis that often requires surgical treatment. A detailed knowledge of the shoulder anatomy and its stabilizing structures is of utmost importance for successful treatment of shoulder instabilities. Identifying anatomic variants (e.g., sublabral hole, meniscoid labrum, cordlike middle glenohumeral ligament, and Buford complex) and distinguishing them from pathologic findings may be especially difficult, as shown by the high interobserver variability. Over the last decade, basic research and arthroscopic surgery have improved our understanding of the shoulder anatomy and pathology. In the context of shoulder instability, injuries of the glenoid (bony Bankart), injuries of the glenoid labrum superiorly (SLAP) or anteroinferiorly (e.g., Bankart, anterior labroligamentous periosteal sleeve avulsion, and Perthes), capsular lesions (humeral avulsion of the glenohumeral ligament), accompanying cartilage lesions (Hill-Sachs, glenolabral articular disruption), and rotator interval and pulley lesions, as well as signs of dynamic instability impingement (posterior-superior impingement, anterior-superior impingement) can be exactly diagnosed (magnetic resonance imaging with intra-articular gadolinium, arthroscopy) and treated (arthroscopy). Therefore the purpose of this article is to review the current literature concerning shoulder anatomy/pathology related to shoulder stability/instability to improve clinical diagnosis and surgical treatment of our patients.

[Arthroscopic treatment strategies for the long head of the biceps tendon]

Shoulder pain is a common issue in orthopedic clinics and the advancement and progress in shoulder arthroscopy has brought new knowledge into the anatomy, pathology and treatment. Affection of the long head of the biceps tendon (LHBT) may be the cause of these disorders. Pathologies of the LHBT are comorbidities of rotator cuff tears or shoulder instability. The following article gives an overview of diseases of the LHBT as well as arthroscopic treatment options.

Biceps tenodesis with interference screw: cyclic testing of different techniques

Different surgical techniques exist for biceps tenodesis. The most secure fixation technique is with interference screws. The purpose of the study was to compare the biomechanical performance of three different interference screw biceps tenodesis fixation methods, which involve different tunnel preparation methods. Using a sheep shoulder model and metal interference screws, a bone wedge technique was compared to serial tunnel dilation and a control group. After a preload, all repairs were cyclically loaded (20-60 N) for 100 cycles followed by destructive testing. Biceps tenodesis using an interference screw--bone wedge technique showed statistically lower cyclic displacement (8.1 ± 6.4 mm) than serial dilatation with an interference screw (21.3 ± 8.4 mm) or interference screw fixation alone (18.3 ± 8.3 mm) (P = 0.02). There were no statistically significant differences in ultimate failure strength for any of the interference screw biceps tenodesis techniques tested. The tunnel preparation method chosen for interference screw fixed biceps tenodesis can have a positive effect on tenodesis performance. Using the bone wedge technique may allow a more rapid rehabilitation program applicable for the traumatic biceps tendon rupture seen in young, athletic patients with high demands.

The effect of the long head of the biceps on glenohumeral kinematics

The long head of the biceps has been described as a stabilizing force in the setting of glenohumeral instability. However, data are lacking on the effect of loading the long head of the biceps on glenohumeral kinematics. Six cadaveric shoulders were tested for glenohumeral rotational range of motion and translation using a custom shoulder testing system and the Microscribe 3DLX (Immersion, San Jose, CA). The path of glenohumeral articulation (PGA) was measured by calculating the humeral head center with respect to the glenoid articular surface at maximal internal rotation, 30 degrees, 60 degrees, 90 degrees, and maximal external rotation. Significant decreases in glenohumeral rotational range of motion and translation were found with 22-N biceps loading vs the unloaded group. With respect to the PGA, the humeral rotation center was shifted posterior with biceps loading at maximal internal rotation, 30 degrees, and 60 degrees of external rotation. Loading the long head of the biceps significantly affects glenohumeral rotational range of motion, translations, and kinematics.

Biceps long head tendon revisited: a case report of split tendon arising from single origin

A 27-year-old, right-hand-dominant woman with a posttraumatic anterior shoulder dislocation 3 months earlier after traffic accident presented because of pain and limited range of motion in the right shoulder. On physical examination, the patient had negative instability tests and a sulcus sign. On arthroscopic examination, a bifurcate long biceps tendon with two limbs was observed about 1 cm distal to the origin in the supraglenoid tubercle. We found no evidence of a tear in the long biceps tendon on probing, and the margin of each limb was smooth and round. Although this anatomic variant may be benign, its presence might be associated with other shoulder pathology. It is interesting to speculate whether the aberrant biceps anatomy in our patient contributed to transfer of injury at dislocation to the rotator cuff rather than to the classic anterior-inferior capsulolabral complex. In addition, recognition of the described anatomic variant on arthroscopy can aid the shoulder surgeon in focusing treatment on the actual pathology.

A biomechanical comparison of two suture anchor configurations for the repair of type II SLAP lesions subjected to a peel-back mechanism of failure

PURPOSE

The purpose of this study was to biomechanically compare 2 different suture anchor configurations in the repair of type II SLAP lesions.

METHODS

Standardized type II SLAP lesions were created in 8 matched pairs of cadaveric shoulders. Two different suture anchor configurations were used to repair the type II SLAP lesions. Group 1 SLAP lesions were repaired with 1 suture anchor placed at the anterior border and a second suture anchor placed at the posterior border of the biceps tendon. Group 2 SLAP lesions were repaired with 2 suture anchors placed posterior to the biceps tendon. Biomechanical testing was conducted in 1 direction. A posterior-directed force, in the plane of the glenoid, simulated the peel-back mechanism that occurs during the late cocking phase of throwing. Biceps-labral complex displacement from the glenoid was measured with 2 miniature displacement transducers. Repair failure (2 mm of posterior labral displacement), ultimate failure, and construct stiffness were measured for each specimen.

RESULTS

The mean load to repair failure was 43.66 N in group 1 and 40.70 N in group 2. The mean load to ultimate failure was 156.28 N in group 1 and 162.06 N in group 2. The mean construct stiffness was 25.91 N/mm in group 1 and 30.28 N/mm in group 2. The differences between the 2 groups were not statistically significant in terms of repair failure, ultimate failure, and construct stiffness.

CONCLUSIONS

When repaired type II SLAP lesions were subjected to a posterior vector load to simulate the peel-back mechanism, the 2 suture anchor configurations were biomechanically equivalent.

CLINICAL RELEVANCE

Placement of an anterior suture anchor could, theoretically, tension the anterior capsulolabral structures via the superior and middle glenohumeral ligaments to the superior labrum. The results of this study suggest that there is no biomechanical advantage to placing an anterior suture anchor and so the use of 2 posterior suture anchors may be preferable in the repair of type II SLAP lesions.

Bifurcate origin of the long head of the biceps tendon

This report illustrates an anatomic variation of the tendon of the long head of the biceps brachii muscle. A bifurcate tendon origin attaching separately onto the supraglenoid tubercle and the posterosuperior capsulolabral tissue is described. The clinical histories and arthroscopic identification of this anatomic finding observed in 2 patients are reviewed. Recognition of the described anatomic variant at arthroscopy can aid the shoulder surgeon in focusing treatment on the actual pathology and not on aberrant anatomy. Several other anatomic variations in the origin of the long head of the biceps brachii have been previously described. The role of a bifurcate biceps tendon origin in the function of the shoulder is unclear.

Mobile superior glenoid labrum: a normal variant or pathologic condition?

BACKGROUND

Arthroscopic differentiation between a pathologic superior labrum anterior posterior lesion and a normal anatomic variant may be difficult.

HYPOTHESIS

Various anatomic patterns exist that systematically characterize superior biceps-labral configurations. One variant involves a mobile superior labrum with exposed articular cartilage on the superior glenoid tubercle. The authors seek to demonstrate that this is nonpathologic.

STUDY DESIGN

A prospective, consecutive descriptive anatomic study with 1-year clinical follow-up of a subgroup with an identified mobile superior labrum.

METHODS

A total of 191 consecutive patients were prospectively evaluated arthroscopically to quantify the dimensions of the labrum and articular cartilage on the supraglenoid tubercle.

RESULTS

A subgroup of 49 patients was identified with articular cartilage on the supraglenoid tubercle, a mobile labrum, and no fibrous tearing or evident injury in this region. In postoperative follow-up, only 1 (2.0%) of these patients was clinically symptomatic in the region of the superior labrum-biceps origin.

CONCLUSIONS

Indication for repair of a mobile superior glenoid labrum must be carefully addressed in the context of normal anatomic morphologic variability. The labral and supraglenoid tubercle morphology was noted to be highly variable.

CLINICAL RELEVANCE

Patients with mobile labral tissue overlying intact articular cartilage, and no evidence of trauma, are not candidates for repair.

Differences in the ultimate strength of the biceps anchor and the generation of type II superior labral anterior posterior lesions in a cadaveric model

BACKGROUND

The pathogenesis of superior labral anterior posterior lesions remains controversial.

HYPOTHESIS

The biceps anchor is more vulnerable to loading with a posterior vector as opposed to an in-line pull.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight pairs of cadaveric shoulders were dissected, and the biceps tendon was loaded to failure in 1 of 2 loading patterns. Loading pattern A was meant to simulate the eccentric load of the biceps in the deceleration phase of throwing; loading pattern B was meant to simulate the posterior biceps load of the late cocking phase.

RESULTS

The biceps anchor demonstrated significantly increased ultimate strength with in-line loading (group A, 508 N) as opposed to posterior loading (group B, 262 N, P < .001). All group B specimens failed at the biceps anchor, resulting in a type II superior labral anterior posterior lesion. Specimens in group A did not create a superior labral anterior posterior lesion.

CONCLUSIONS

Direction of biceps loading resulted in significant differences in the ultimate strength of the biceps anchor and the generation of superior labral anterior posterior lesions. The biceps anchor was significantly weaker when loaded with a posterior vector.

RELEVANCE

The superior labrum may be most vulnerable to injury in late cocking. The reproducible generation of type II superior labral anterior posterior lesions may have applications as a biomechanical model.

A biomechanical comparison of repair techniques for type II SLAP lesions

BACKGROUND

Multiple options exist for repair of superior labral tears.

PURPOSE

To compare commonly used fixation techniques for superior labral tears.

STUDY DESIGN

Biomechanical cadaveric study.

METHODS

A comparison of the initial strengths of fixation for type II superior labral anterior posterior (SLAP) lesions was performed in three cadaveric shoulder groups, each containing seven specimens. Two groups were repaired with screw-in anchors; one group had vertical sutures, the other horizontal. Group 3 was repaired using bioabsorbable tacks. Cyclic traction was applied to the biceps tendon. Repair failure (2 mm of permanent displacement) and ultimate failure were measured.

RESULTS

Specimen stiffness was similar between groups. The mean load to repair failure was 123 +/- 17 N in group 1, 114 +/- 11 N in group 2, and 95 +/- 13 N in group 3. The mean load to ultimate failure was 163 +/- 15 N, 161 +/- 12 N, and 145 +/- 12 N, respectively. Although the repair failure loads of groups 1 and 2 were 29% and 17%, respectively, greater than the tack group, the differences were not statistically significant (P >.05). All ultimate failures occurred at the labral-implant interface.

CONCLUSION

Initial fixation strength of tissue tack and suture anchor repairs of SLAP lesions are comparable.

Diagnosis and Management of the Painful Shoulder. Part 2: Examination, Interpretation, and Management

Diagnosis, interpretation and subsequent management of shoulder pathology can be challenging to clinicians. Because of its proximal location in the schlerotome and the extensive convergence of afferent signals from this region to the dorsal horn of the spinal cord, pain reference patterns can be broadly distributed to the deltoid, trapezius, and or the posterior scapular regions. This pain behavior can make diagnosis difficult in the shoulder region, as the location of symptoms may or may not correspond to the proximity of the pain generator. Therefore, a thorough history and reliable physical examination should rest at the center of the diagnostic process. Effective management of the painful shoulder is closely linked to a tissue-specific clinical examination. Painful shoulder conditions can present with or without limitations in passive and or active motion. Limits in passive motion can be classified as either capsular or noncapsular patterns. Conversely, patients can present with shoulder pain that demonstrates no limitation of motion. Bursitis, tendopathy and rotator cuff tears can produce shoulder pain that is challenging to diagnose, especially when they are the consequence of impingement and or instability. Numerous nonsurgical measures can be implemented in treating the painful shoulder, reserving surgical interventions for those patients who are resistant to conservative care.

Anatomy of the superior glenoid rim. Repair of superior labral anterior to posterior tears

BACKGROUND

Successful placement of a fixation device on the superior glenoid rim during superior labrum repairs requires accurate knowledge of the glenoid rim anatomy.

PURPOSE

To investigate the normal bony anatomy of the superior glenoid rim.

STUDY DESIGN

Descriptive anatomic study.

METHODS

Twenty cadaveric glenoid specimens were scanned to obtain cross-sectional images with peripheral quantitative computed tomography in three different positions, each perpendicular to the articular surface. Two straight lines were drawn along the interior bony margins of the articular surface and cortex, and image analysis software was used to calculate the angle between these lines. Three bony angles were measured.

RESULTS

The bony angles from the 10:30-, 12-, and 1:30-o'clock cross-sections were 55 degrees +/- 5 degrees, 64 degrees +/- 5 degrees, and 62 degrees +/- 8 degrees, respectively. The posterosuperior angle (at the 10:30-o'clock position) was statistically significantly lower than the superior and anterosuperior angles. Intraobserver variation was less than 3%.

CONCLUSIONS

The most superior point of the glenoid rim (12-o'clock position) seems to provide the most bone stock for anchor insertion. The available bone support was found to decrease posteriorly on the glenoid rim.

CLINICAL RELEVANCE

During superior labral repairs, the anchor or fixation device should be inserted at approximately a 30 degrees angle in relation to the articular surface for maximal bone support.