Relationships of the musculocutaneous nerve and the coracobrachialis during coracoid abutment procedure (Latarjet procedure)

Changes in Scapular Function, Shoulder Strength, and Range of Motion Occur After Latarjet Procedure

Purpose

To evaluate the current literature on the effects of anatomic changes caused by the Latarjet procedure and to identify areas for future research.

Methods

English-language studies that addressed the consequences of anatomic alterations after the open Latarjet procedure were included. Articles written in languages other than English, reviews, and case reports were excluded. Titles and abstracts were screened by 2 authors. Studies that met the inclusion criteria were screened by the same authors. The following data were extracted from the included studies: authors, year of publication, journal, country of origin, aims or purpose, study population and sample size, methods, procedure, intervention type, and key findings that relate to the scoping review questions.

Results

Twenty-two studies were included for analysis, yielding the following findings: First, the Latarjet procedure may change the position of the scapula owing to pectoralis minor tenotomy and/or transfer of the conjoint tendon. Second, dissection of the coracoacromial ligament may result in increased superior translation of the humeral head. The impact of this increased translation on patients' function remains unclear. Third, the subscapularis split shows, overall, better internal rotation strength compared with subscapularis tenotomy. Fourth, passive external rotation may be limited after capsular repair. Fifth, despite the movement of the conjoint tendon, elbow function seems unchanged. Finally, the musculocutaneous nerve is lengthened with a changed penetration angle into the coracobrachialis muscle, but the clinical impact seems limited.

Conclusions

The Latarjet procedure leads to anatomic and biomechanical changes in the shoulder. Areas of future research may include better documentation of scapular movement (bilateral, as well as preoperative and postoperative) and elbow function, the effect of (degenerative) rotator cuff ruptures after the Latarjet procedure on shoulder function, and the impact of capsular closure and its contribution to the development of glenohumeral osteoarthritis.

Clinical Relevance

This comprehensive overview of anatomic changes after the Latarjet procedure, with its effects on shoulder and elbow function, showed gaps in the current literature. Orthopaedic shoulder surgeons and physical therapists could use our findings when providing patient information and performing future clinical research.

Coracobrachialis muscle morphology and coexisted neural variants: a cadaveric case series

PURPOSE

The current cadaveric case series evaluates the coracobrachialis muscle morphology, the related musculocutaneous nerve origin, course, and branching pattern, as well as associated adjacent neuromuscular variants.

MATERIALS AND METHODS

Twenty-seven (24 paired and 3 unpaired) cadaveric arms were dissected to identify the coracobrachialis possible variants with emphasis on the musculocutaneous nerve course and coexisted neural variants.

RESULTS

Four morphological types of the coracobrachialis were identified: a two-headed muscle in 62.96% (17/27 arms), a three-headed in 22.2% (6/27), a one-headed in 11.1% (3/27), and a four-headed in 3.7% (1 arm). A coracobrachialis variant morphology was identified in 37.04% (10/27). A three-headed biceps brachii muscle coexisted in 23.53% (4/17). Two different courses of the musculocutaneous nerve were recorded: 1. a course between coracobrachialis superficial and deep heads (in cases of two or more heads) (100%, 24/24), and 2. a medial course in case of one-headed coracobrachialis (100%, 3/3). Three neural interconnections were found: 1. the lateral cord of the brachial plexus with the medial root of the median nerve in 18.52%, 2. the musculocutaneous with the median nerve in 7.41% and 3. the radial with the ulnar nerve in 3.71%. Duplication of the lateral root of the median nerve was identified in 11.1%.

CONCLUSIONS

The knowledge of the morphology of the muscles of the anterior arm compartment, especially the coracobrachialis variant morphology and the related musculocutaneous nerve variable course, is of paramount importance for surgeons. Careful dissection and knowledge of relatively common variants play a significant role in reducing iatrogenic injury.

A Bilateral Symmetric Accessory Coracobrachialis Muscle Combined With an Interconnection of the Musculocutaneous Nerve With the Median Nerve

This report describes a bilateral symmetric accessory coracobrachialis muscle variant coexisting with a unilateral interconnection of the musculocutaneous nerve and the median nerve. An 80-year-old female cadaver was dissected. The bilateral coracobrachialis muscle variant consisted of three heads: two superficial heads and one deep head. One superficial head arose from the tip of the coracoid process, while the other originated from the short head tendon of the biceps brachii. The deep head of the coracobrachialis muscle emerged from the base of the coracoid process. The musculocutaneous nerve bilaterally coursed between the superficial and deep heads. On the right side, the three-headed coracobrachialis muscle coexisted with an ipsilateral interconnection of the musculocutaneous nerve and the median nerve, located at the lower third of the arm. While the presence of a unilateral three-headed coracobrachialis muscle is not rare (with a prevalence range of 0-22.2%), as well as the distal interconnection between the musculocutaneous nerve and the median nerve at the lower third of the arm (with a prevalence range of 1.8-53.6%), the coexistence of the current bilateral three-headed coracobrachialis muscle variant with the distal interconnection of the musculocutaneous and median nerves is quite unusual. A similar report underscores the finding of the bilateral coracobrachialis muscle variant.

Proportional localisation of the entry point of the coracobrachialis muscle by the musculocutaneous nerve along the humerus

PURPOSE

To project the distance between the tip of the greater tubercle (GT), respectively, the proximal border of the tip of the coracoid process (CP) and the entry point of the coracobrachialis by the musculocutaneous nerve (MCN) proportionally onto the humeral length.

METHODS

Sixty-six upper extremities were included in the study. The distance between the tip of the GT and the distal tip of the lateral humeral epicondyle (LE) was evaluated as the humeral length (HL). The interval between the tip of the GT and the entry point of the coracobrachialis muscle by the MCN was measured. The distance between the proximal border of the tip of the CP and the distal portion of the medial humeral epicondyle (ME) and the entry point of the MCN into the coracobrachialis were evaluated. Proportions were used to project the entry point of the coracobrachialis by the MCN along the HL, respectively, the interval between the proximal border of the tip of the CP and the distal tip of the ME.

RESULTS

The entry point of the MCN into the coracobrachialis muscle can be expected at an interval between 14.9 and 33.9% of the HL (between the tip of the GT and the LE), starting from the tip of the GT. Regarding the reference line between the proximal border of the CP and the ME, the nerve's entry point was located between 14.2 and 34.4%, starting from the CP.

CONCLUSION

Results represent easily applicable intervals for intraoperative localisation of the MCN.

A rare bilateral variant of the coracobrachialis muscle with supernumerary heads and coexisted variant branching patterns of the brachial plexus and the axillary artery

PURPOSE

The study report describes a rare bilateral variant of a six- and five-headed coracobrachialis muscle (CB). The musculocutaneous nerve (MCN) (bilaterally) and the median nerve (MN) lateral root (unilaterally) pierced CB heads, separating superficial from deep heads.

METHODS

The variant bilateral CB was identified in a 78-year-old formalin-embalmed male cadaver, derived from a body donation program after a signed informed consent.

RESULTS

At the right side: The 6-headed CB was pierced by the MCN, while the MN lateral root pierced the one superficial and deep head. CB was supplied by the lateral cord and the MCN. At the left side: A 5-headed CB was identified with three superficial distinct origins that fused into a common superficial head coursing anterior to MCN. The variant CB bilaterally (with 11 heads in total) coexisted with a MN variant formation, an atypical course of the MN lateral root through CB (right side), a connection of the MN lateral root with the MCN (left side) and a variant axillary artery branching pattern (bilaterally).

CONCLUSIONS

Course and direction of the accessory CB heads may occasionally entrap the MCN and/or adjacent structures (brachial artery and MN). The MCN compression results in problems in the glenohumeral joint flexion and adduction, and tingling or numbness of the elbow joint, the forearm lateral parts and the hand.

Biomechanical comparison between various screw fixation angles for Latarjet procedure: a cadaveric biomechanical study

BACKGROUND

The Latarjet procedure is a reliable treatment for the management of anterior glenohumeral instability with glenoid bone loss. However, the biomechanical properties of different fixation angles between screw and glenoid surface (α angle) have rarely been studied. The aim of the study was to investigate and compare the fixation stability, failure load, and failure mechanism between different α angles for Latarjet procedures, which were performed on cadaver specimens.

METHODS

Twenty-four shoulder specimens (8 in each of 3 groups) were dissected free of all soft tissue, and a 25% glenoid defect was created. The coracoid process was osteomized and fixed with 2 screws at 3 different α angles: 0° (group A), 15° (group B), and 30° (group C). Specimens were mounted to a testing apparatus, and cyclic loading (100 cycles at 1 Hz) was applied with a staircase protocol (50, 100, 150, and 200 N). Gross graft displacement and interface displacement were measured. The ultimate failure loads and failure mechanisms were recorded.

RESULTS

There was no significant difference in gross displacement under any cyclic load between 3 groups. However, a significant larger interface displacement was noted in group C than in group A in 150-N cyclic loading (P = .017). Under failure strength testing, all 24 specimens failed because of screw cutout from the glenoid, and the ultimate failure load was similar among the three groups.

CONCLUSION

Compared with the 0° α angle, the displacement after cyclic loading did not significantly increase when the α angle was increased to 15° but significantly increased at 30° for Latarjet procedures, which were performed on cadaver specimens. The results suggest that surgeons should apply the screws as parallel as possible to the glenoid surface when performing the Latarjet procedure. Although mild deviation may not reduce fixation stability, α angles greater than 30° should be avoided.

Incidence, Risk Factors, Prevention, and Management of Peripheral Nerve Injuries Following Shoulder Arthroplasty

In this article, the authors review the incidence and causes of iatrogenic peripheral nerve injuries following shoulder arthroplasty and provide preventative measures to decrease nerve injury rate and management options. They describe common direct and indirect causes of injury such as laceration and retractor use versus arm positioning and lengthening, respectively. Preventative measures include an understanding of anatomy and high-risk locations in the shoulder, minimizing extreme ranges of arm motion and utilization of intraoperative nerve monitoring. Lastly, the authors review diagnosis and management of neurologic symptoms including how and when to use electrodiagnostic studies, nerve grafts, transfers, or muscle/tendon transfers.

Prevention and Treatment of Nerve Injuries in Shoulder Arthroplasty

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Nerve injuries during shoulder arthroplasty have traditionally been considered rare events, but recent electrodiagnostic studies have shown that intraoperative nerve trauma is relatively common.

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The brachial plexus and axillary and suprascapular nerves are the most commonly injured neurologic structures, with the radial and musculocutaneous nerves being less common sites of injury.

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Specific measures taken during the surgical approach, component implantation, and revision surgery may help to prevent direct nerve injury. Intraoperative positioning maneuvers and arm lengthening warrant consideration to minimize indirect injuries.

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Suspected nerve injuries should be investigated with electromyography preferably at 6 weeks and no later than 3 months postoperatively, allowing for primary reconstruction within 3 to 6 months of injury when indicated. Primary reconstructive options include neurolysis, direct nerve repair, nerve grafting, and nerve transfers.

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Secondary reconstruction is preferred for injuries presenting >12 months after surgery. Secondary reconstructive options with favorable outcomes include tendon transfers and free functioning muscle transfers.

Complications after open Latarjet procedure: influence of arm positioning on musculocutaneous and axillary nerve function

BACKGROUND

Alterations in the anatomical relationships of the musculocutaneous (MCN) and axillary nerves and the influence of arm positioning on these relationships after a Latarjet procedure have been demonstrated in the cadaver, but there are no studies in the literature that establish if there is any neurophysiological repercussion.

METHODS

We retrospectively identified 24 patients with a primary or revision open Latarjet procedure. A prospective clinical (Constant-Murley, Rowe and Walch-Duplay and active range of motion), radiographic (with CT), and electrodiagnostic evaluation was made at the most recent follow-up.

RESULTS

Nonunion occurred in four patients (22%); there were, as well, one case of partial coracoid reabsorption (5%) and two (11%) with mild glenohumeral osteoarthritis. In the anatomical position, we found no alterations in the musculocutaneous nerve and two cases (11%) in the axillary nerve slight motor unit loss. In the risk position, 11 cases (61%) had neurophysiological involvement (36% had neurophysiological changes in the musculocutaneous nerve and 64% in the axillary nerve). No differences between patients with or without neurophysiologic changes were found: Constant 87/83; Rowe 89/90; Walch-Duplay 84/78; Forward elevation 175º/170º, abduction 165°/175°; external rotation 48°/45°.

CONCLUSION

The rate of clinical electromyographic changes in the axillary and MCN in the abducted and externally rotated arm position (risk dislocation position) is higher than in neutral position. Nonunion of the coracoid process must play a role in these neurophysiological changes. Although in the medium-term they don't have clinical impact, further randomized prospective studies with a larger sample size are necessary to determine their true repercussion.

LEVEL OF EVIDENCE

Level IV.

A New Guide for the Arthroscopically Assisted Latarjet Procedure

The Latarjet procedure is a commonly used treatment for recurrent shoulder instability. However, its neurological complication rate has been reported to be as high as 10%. During the Latarjet procedure, the neurovascular structures are relocated inferiorly and medially. I hypothesized that the risk of nerve injury would be reduced by assisting the inferior-medial relocation of the neurovascular structures intraoperatively.

Methods

Seventeen consecutive patients with shoulder instability accompanied by glenoid bone loss were treated with an all-arthroscopic Latarjet procedure assisted by the novel low-profile SaSumata (SS) guide. The SS guide is inserted through a portal made above the coracoid process and is attached to the coracoid process by 2 pre-fix screws (i.e., temporary pre-fixation screws). Unlike previous techniques, the SS guide is not shuttled from 1 portal to the other to redirect the bone graft from the donor site to the recipient site; instead, it remains attached to the graft throughout the procedure. The SS guide brings the coracoid graft along an inferior-medial trajectory, pushing aside the neurovascular structures with the help of a switching stick. Owing to its semicircular pronged head, the SS guide holds the graft until the pre-fix screws are exchanged with permanent screws. All patients were clinically assessed and underwent computed tomography (CT) scans.

Results

This maneuver was performed arthroscopically in 17 patients, with no conversion to open surgery and no neurological injuries. No patient had recurrence of dislocation after follow-up for a minimum of 24 months. The mean Subjective Shoulder Value was 87.5% ± 11.7%. The mean Rowe score was 88 ± 15.7. The bone block was optimally positioned between 3 o'clock and 5 o'clock and was flush with the glenoid facet in 16 of the 17 patients. There was 1 fracture of the bone block. The mean operation time after the first 5 patients was 125 ± 23 minutes.

Conclusions

The SS guide was a useful tool for performing the arthroscopically assisted Latarjet procedure for recurrent anterior shoulder instability, with good functional results.

Level of Evidence

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Arthroscopic Bankart Repair With Remplissage in Comparison to Bone Block Augmentation for Anterior Shoulder Instability With Bipolar Bone Loss: A Systematic Review

PURPOSE

The purpose of this systematic review is to examine the rates of postoperative recurrence of instability, functional outcomes, and complications after treatment with bone augmentation procedures or arthroscopic Bankart repair with remplissage for recurrent anterior shoulder instability in the setting of subcritical glenoid bone loss.

METHODS

EMBASE, PubMed, and MEDLINE were searched from database inception until June 2019 for articles examining either bone block augmentation to the glenoid or Bankart repair with remplissage (BRR) in the setting of subcritical glenoid bone loss. Search and data extraction were performed by 2 reviewers independently and in duplicate. A separate analysis was done for comparative studies.

RESULTS

Overall, 145 studies were identified, including 4 comparative studies. Across all studies, postoperative recurrence rates ranged from 0% to 42.8% for bone block augmentation and 0% to 15% for Bankart repair with remplissage. In comparative studies reporting subcritical glenoid bone loss, rates were 5.7% to 11.6% in the Latarjet group and 0% to 13.3% in the Bankart repair with remplissage group. However, in all studies reporting 10% to 15% mean glenoid bone loss, there was an increased rate of recurrent instability with arthroscopic soft tissue repair (6.1% to 13.2%) in comparison with bony augmentation (0% to 8.2%). Lastly, complication rates ranged from 0% to 66.7% for the bone block group and 0% to 2.3% for arthroscopic Bankart repair with remplissage.

CONCLUSION

Both bone block augmentation and Bankart repair with remplissage are effective treatment options for recurrent anterior shoulder instability in patients with bipolar bone loss but subcritical glenoid bone loss. Both have comparable functional outcomes, albeit bone block procedures carry an increased risk of complications. Arthroscopic BRR may be associated with a higher failure rate for preoperative glenoid bone loss >10%. Therefore, it may represent a stabilization procedure best suited for cases of recurrent anterior instability with glenoid bone loss <10% and the presence of a significant, off-track Hill-Sachs lesion.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II-IV studies.

Relationship of the Musculocutaneous Nerve and Its Twigs to the Coracoid Process: An Operative Exposure

Background:

A musculocutaneous nerve (MCN) injury is a rare complication of the Latarjet procedure. Most of these injuries are neurapraxias and resolve with time; however, permanent injuries can occur. Understanding the anatomy and relationship of the MCN to the coracoid process is essential to prevent injuries.

Purpose:

To provide realistic, in situ–referenced measurements for the Latarjet procedure.

Study Design:

Descriptive laboratory study.

Methods:

A total of 12 matched-pair cadaveric specimens (24 fresh-frozen shoulders) were dissected. Coracoid osteotomy was performed, and the MCN and its respective twigs were identified. Measurements were made from the coracoid process to the entry site of the nerve twigs and trunk into the coracobrachialis muscle.

Results:

Overall, 70.8% of specimens had twigs; however, there was a discrepancy in the presence (41.7%) and number (75.0%) of twigs in the paired specimens. The most proximal twigs were, on average, 33.5 ± 8.1 mm (range, 21.9-47.6 mm) from the coracoid process. The main trunk was, on average, 51.1 ± 14.4 mm (range, 16.7-71.9 mm) from the coracoid process. In 33.3% of specimens, the nerve entered the coracobrachialis at a distance shorter than 5 cm below the coracoid process, and this increased to 91.7% when the twigs were accounted for.

Conclusion:

The previously described safe zone of 5 cm below the coracoid process may not be reliable to protect the MCN or its twigs. Using 3 cm would decrease the chances of damaging a twig or the main trunk. In 33.3% of the specimens, the nerve entered the coracobrachialis at a distance shorter than 5 cm below the coracoid process, and this increased to 91.7% when twigs were accounted for.

Clinical Relevance:

As the Latarjet procedure is an emerging technique, it is essential to be aware of the anatomic structures and the relation between different neural structures to anatomic points of reference. Therefore, the results of this study add significant information for a safe surgical procedure for the majority of patients suffering from shoulder instability.

The co-occurrence of a four-headed coracobrachialis muscle, split coracoid process and tunnel for the median and musculocutaneous nerves: the potential clinical relevance of a very rare variation

The coracobrachialis muscle (CBM) originates from the apex of the coracoid process, in common with the short head of the biceps brachii muscle, and from the intermuscular septum. Both the proximal and distal attachment of the CBM, as well as its relationship with the musculocutaneus nerve demonstrate morphological variability, some of which can lead to many diseases. The present case study presents a new description of a complex origin type (four-headed CBM), as well as the fusion of both the short biceps brachii head, brachialis muscle and medial head of the triceps brachii. In addition, the first and second heads formed a tunnel for the musculocutaneus and median nerves. This case report has clear clinical value due to the split mature of the coracoid process, and is a significant indicator of the development of interest in this overlooked muscle.

Biomechanical Analysis of Plate Fixation Compared With Various Screw Configurations for Use in the Latarjet Procedure

Background:

The biomechanical properties of coracoid fixation with a miniplate during the Latarjet procedure have not been described.

Purpose:

To determine the biomechanical properties of miniplate fixation for the Latarjet procedure compared with various screw fixation configurations.

Study Design:

Controlled laboratory study.

Methods:

A total of 8 groups (n = 5 specimens per group) were tested at a screw insertion angle of 0°: (1) 3.75-mm single screw, (2) 3.75-mm double screw, (3) 3.75-mm double screw with washers, (4) 3.75-mm double screw with a miniplate, (5) 4.00-mm single screw, (6) 4.00-mm double screw, (7) 4.00-mm double screw with washers, and (8) 4.00-mm double screw with a miniplate. In addition, similar to groups 1 to 3 and 5 to 7, there were 30 additional specimens (n = 5 per group) tested at a screw insertion angle of 15° (groups 9-14). To maintain specimen uniformity, rigid polyurethane foam blocks were used. Testing parameters included a preload of 214 N for 10 seconds, cyclical loading from 184 to 736 N at 1 Hz for 100 cycles, and failure loading at a rate of 15 mm/min until 10 mm of displacement or specimen failure occurred.

Results:

All single-screw constructs and 77% of 15° screw constructs failed before the completion of cyclical loading. Across all groups, group 8 (4.00-mm double screw with miniplate) demonstrated the highest maximum failure load (P < .001). There were no differences in failure loads among specimens with single-screw fixation (groups 1, 5, 9, and 12; P > .05). All specimens in groups 9, 10, 11, 12, 13, and 14 (insertion angle of 15°) had significantly lower maximum failure loads compared with specimens in groups 2, 3, 4, 6, 7, and 8 (insertion angle of 0°) (P < .001 for all).

Conclusion:

These results indicate significantly superior failure loads with the miniplate compared with all other constructs. Across all fixation techniques and screw sizes, constructs with screws inserted at 0° performed better than constructs with screws inserted at 15°.

Clinical Relevance:

The use of a miniplate for coracoid fixation during the Latarjet procedure may provide a more durable construct for the high-demand contact athlete.

Changes in the Neurovascular Anatomy of the Shoulder After an Open Latarjet Procedure: Defining a Surgical Safe Zone

BACKGROUND

Although previous literature has described the relevant anatomy for an open anterior Bankart approach of the shoulder, there is little known regarding the anatomic relationship changes in the neurovascular structures after an open Latarjet procedure.

PURPOSE

To define the neurovascular anatomy of the native shoulder in relation to the coracoid and to define the anatomy after the Latarjet procedure in relation to the glenoid to determine distances to these neurovascular structures with and without neurolysis of the musculocutaneous nerve (MCN) from the conjoint tendon.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Fourteen fresh-frozen male cadaveric shoulders (7 matched pairs) were utilized. The distances of 7 neurovascular structures (the main trunk of the MCN at its insertion into the conjoint tendon, the MCN at its closest location to the coracoid process, the lateral cord of the plexus, the split of the lateral cord and MCN, the posterior cord of the plexus, the axillary nerve, and the axillary artery) to pertinent landmarks were first measured in the native state in relation to the coracoid. After the Latarjet procedure, these landmarks were measured in relation to the glenoid. In addition, measurements of the MCN distances were performed both with and without neurolysis of the MCN from the conjoint tendon. All measurements were performed using digital calipers and reported as medians with ranges.

RESULTS

The median MCN entry into the conjoint tendon was 56.5 mm (range, 43.0-82.2 mm) and 57.1 mm (range, 23.5-92.9 mm) from the tip of the coracoid in the neurolysis group and nonneurolysis group, respectively ( P = .32). After the Latarjet procedure, the median MCN entry into the conjoint tendon was 43.8 mm (range, 20.2-58.3 mm) and 35.6 mm (range, 27.3-84.5 mm) from the 3-o'clock position of the glenoid in the neurolysis and nonneurolysis groups, respectively ( P = .83). The median MCN entry into the conjoint tendon was 35.6 mm (range, 25.1-58.0 mm) and 36.3 mm (range, 24.4-77.9 mm) from the 6-o'clock position in the neurolysis group and nonneurolysis group, respectively ( P = .99). After the Latarjet procedure, the closest neurovascular structures in relation to both the 3-o'clock and 6-o'clock positions to the coracoid were the axillary nerve at a median 27.4 mm (range, 19.8-40.0 mm) and 27.7 mm (range, 23.2-36.1 mm), respectively.

CONCLUSION

This study identified a minimum distance medial to the glenoid after the Latarjet procedure to be approximately 19.8 mm for the axillary nerve, 23.6 mm for the posterior cord, and 24.4 mm and 20.2 mm for the MCN without and with neurolysis, respectively. Neurolysis of the MCN did not significantly change the distance of the nerve from pertinent landmarks compared with no neurolysis, and routine neurolysis may not be indicated. However, the authors still advise that there may be clinical benefit to performing neurolysis during surgery, especially given that the short length of the MCN puts it at risk for traction injuries during the Latarjet procedure.

CLINICAL RELEVANCE

The findings of this study provide an improved understanding of the position of the neurovascular structures after the Latarjet procedure. Knowledge of these minimum distances will help avoid iatrogenic damage of the neurovascular structures when performing procedures involving transfer of the coracoid process.

Dynamic Anterior Stabilization Using the Long Head of the Biceps for Anteroinferior Glenohumeral Instability

Anteroinferior glenohumeral instability can be treated by variants of the Bankart repair, remplissage, and the Latarjet procedure, although all options remain associated with complications, including recurrence, stiffness, persistent pain, apprehension, and dislocation arthropathy. The authors therefore thought of a concept of dynamic anterior stabilization to treat anteroinferior glenohumeral instability by transferring the long head of the biceps within a subscapularis split to the anterior glenoid margin, thereby creating a "sling effect" by using a conservative technique. A standard Bankart repair is then to re-establish the labral damper effect. The main benefit of the dynamic anterior stabilization procedure is that it grants the "sling effect," but is easier and safer than arthroscopic Latarjet. It does not require screws nor traction of the coracoid process, and should therefore reduce the risks of neurologic damage. Furthermore, the procedure can be performed with only 3 small incisions, because it does not require coracoid transfer, which eliminates risks of nerve dissection, graft overhang, and cortical resorption, hence reducing the probability for dislocation arthroplasty. Lastly, the pectoralis minor remains intact, which would avoid scapular dyskinesis.

Nerves Around the Shoulder: What the Radiologist Should Know?

Peripheral neuropathies of the shoulder are common and could be related to traumatic injury, shoulder surgery, infection or tumour but usually they result from an entrapment syndrome. Imaging plays an important role to detect the underlying causes, to assess the precise topography and the severity of nerve damage. The key points concerning the imaging of nerve entrapment syndrome are the knowledge of the particular topography of the injured nerve, and the morphology as well signal modifications of the corresponding muscles. Magnetic Resonance Imaging best shows these findings, although Ultrasounds and Computed Tomography sometimes allow the diagnosis of neuropathy.

Autologous distal clavicle versus autologous coracoid bone grafts for restoration of anterior-inferior glenoid bone loss: a biomechanical comparison

BACKGROUND

Treating anterior glenoid bone loss in patients with recurrent shoulder instability is challenging. Coracoid transfer techniques are associated with neurologic complications and neuroanatomic alterations. The purpose of our study was to compare the contact area and pressures of a distal clavicle autograft with a coracoid bone graft for the restoration of anterior glenoid bone loss. We hypothesized that a distal clavicle autograft would be as effective as a coracoid graft.

METHODS

In 13 fresh-frozen cadaveric shoulder specimens, we harvested the distal 1.0 cm of each clavicle and the coracoid bone resection required for a Latarjet procedure. A compressive load of 440 N was applied across the glenohumeral joint at 30° and 60° of abduction, as well as 60° of abduction with 90° of external rotation. Pressure-sensitive film was used to determine normal glenohumeral contact area and pressures. In each specimen, we created a vertical, 25% anterior bone defect, reconstructed with distal clavicle (articular surface and undersurface) and coracoid bone grafts, and determined the glenohumeral contact area and pressures. We used analysis of variance for group comparisons and a Tukey post hoc test for individual comparisons (with P <.05 indicating a significant difference).

RESULTS

The articular distal clavicle bone graft provided the lowest mean pressure in all testing positions. The coracoid bone graft provided the greatest contact area in all humeral positions, but the difference was not significant.

CONCLUSION

An articular distal clavicle bone graft is comparable in glenohumeral contact area and pressures to an optimally placed coracoid bone graft for restoring glenoid bone loss.

LEVEL OF EVIDENCE

Basic Science Study; Biomechanics.

The Anatomic Basis for the Arthroscopic Latarjet Procedure: A Cadaveric Study

BACKGROUND

The Latarjet technique is a reliable treatment option for recurrent anterior shoulder instability. However, the complication rate has been reported to be as high as 30%, with 1.6% of patients suffering a nerve injury. The all-arthroscopic Latarjet procedure has been gaining popularity, even as it has introduced its own challenges. Given that the surgeon is not able to palpate the nerves, their localization and protection can be difficult. Additionally, the use of different instruments can lead to distinct nerve injury mechanisms.

PURPOSE

To describe the anatomic trajectory of the musculocutaneous, axillary, and suprascapular nerves in relation to the arthroscopic Latarjet approach. Using this information, guidance is provided for reducing nerve injuries during instrumentation and screw insertion.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 50 cadaveric shoulders from 25 whole-body specimens were examined. The specimens were placed in the beach-chair position, and the deltopectoral and dorsal approaches were used to expose the relevant structures. A subscapularis muscle split was performed between the inferior and middle thirds of the tendon. Digital caliper measurements were taken between various points of the trajectories of the nerves and surrounding anatomic landmarks. The location of the nerves relative to the split was recorded.

RESULTS

The musculocutaneous nerve lay within the split in 66% of the shoulders (n = 33); it was medial to the split in 28% (n = 14); it was found lateral to split in 2% (n = 1); and it was not identified in 4% of shoulders (n = 2). The mean length of the axillary nerve was 4.0 cm (95% CI, 3.7-4.2) from the exit of the plexus to the quadrangular space. The axillary nerve was found to be within the split in 50% of the shoulders (n = 25) and medial to the split in the remaining 50% (n = 25). The suprascapular nerve at the level of the supraspinatous fossa passed 3.3 cm (95% CI, 3.1-3.5) medial to the superior rim of the posterior glenoid. The nerve curves around the root of the spine at the spinoglenoid notch level, approximating the glenoid rim to a distance of 2.1 cm (95% CI, 2.0-2.2). Finally, the nerve runs medially again before branching out into smaller fibers to innervate the infraspinatus muscle at a distance of 2.9 cm (95% CI, 2.7-3.1) from the inferior glenoid rim. Based on these findings, there is an approximately 2 cm-wide safe zone from the edge of the glenoid rim for the insertion of graft-fixing screws.

CONCLUSION

When performing a subscapularis split in the arthroscopic Latarjet procedure, the risk of injuries to the musculocutaneous and axillary nerves could be reduced by aiming the switching stick inserted through the posterior portal toward the lateral edge of the intended location of the split. Injuries to the suprascapular nerve could be prevented by aiming the graft-fixing screws laterally toward the edge of the glenoid rim.

CLINICAL RELEVANCE

This study clarifies the location of the nerves relevant to the arthroscopic Latarjet technique and provides anatomic information that could help the surgeon reduce the risk of injuries to the musculocutaneous, axillary, and suprascapular nerves.

Coracobrachialis muscle: morphology, morphometry and gender differences

PURPOSE

Coracobrachialis (CBM) is a complex muscle with a wide range of variations in its morphology and innervation. The goal of this study was to elucidate the morphology, morphometry, gender differences of CBM and precise anatomical position of the musculocutaneous nerve (MCN) with reference to surrounding anatomical landmarks in an adult Sri Lankan population.

METHOD

Cadaveric upper limbs (n = 312) were examined for the proximal and distal attachments, length, width, thickness of CBM and its relationship with the MCN.

RESULTS

The CBM originated from the tip of the coracoid process of the scapula and lateral, posterior and medial aspects of the tendon of short head of biceps brachii. Gender differences were observed in all morphometrical parameters of CBM. In 83.33 %, MCN perforated the CBM. In 50 % the MCN pierced the middle one-third of CBM while none pierced the lower one-third. The distance from the coracoid process to the point of entry of MCN into CBM (distance P) was 50.62 mm. A positive correlation was observed between the arm length and distance P indicating that arm length provides an accurate and reliable means of gauging the distance P of an individual.

CONCLUSION

The present study provides new evidence pertaining to the origin of CBM. Further, it was revealed that the predicted distance P of any upper extremity can be calculated by dividing the arm length by 5. Precise anatomical location of MCN in relation to CBM using unequivocal and well-defined anatomical landmarks will be imperative in modern surgical procedures.

Complications of the Latarjet procedure

The Latarjet procedure is an operation performed either arthroscopically or open for recurrent anterior shoulder instability, in the setting of glenoid bone loss; with good to excellent functional results. Despite excellent clinical results, the complication rates are reported between 15 and 30 %. Intraoperative complications such as graft malpositioning, neurovascular injury, and graft fracture can all be mitigated with meticulous surgical technique and understanding of the local anatomy. Nonunion and screw breakage are intermediate-term complications that occur in less than 5 % of patients. The long-term complications such as graft osteolysis are still an unsolved problem, and future research is required to understand the etiology and best treatment option. Recurrent instability after the Latarjet procedure can be managed with iliac crest bone graft reconstruction of the anterior glenoid. Shoulder arthritis is another complication reported after the Latarjet procedure, which poses additional challenges to both the surgeon and patient.

Pectoralis minor tendon transfer for irreparable anterosuperior cuff tears

BACKGROUND

Tears of the subscapularis tendon are a frequent cause of shoulder dysfunction. Tendon transfer techniques have been devised to treat irreparable tears. The objectives of this study were to explore the anatomic feasibility of using the pectoralis minor tendon as a graft for subscapularis tendon tears, the safety of the procedure, and the scope of this approach in improving shoulder function.

MATERIALS AND METHODS

We performed open pectoralis minor transfer in 27 patients (22 men; mean age, 60 years) with irreparable tears of the upper two-thirds of the subscapularis tendon, grade III fatty degeneration, and irreparable supraspinatus tears. Constant and Simple Shoulder Test scores and functional outcomes were evaluated at 3, 12, and 24 months. All patients were available for follow-up.

RESULTS

The pectoralis minor tendon easily reached the subscapularis footprint. There were no cases of musculocutaneous nerve or brachial plexus injury or graft failure. Active forward flexion improved from 127° to 177°; external rotation with the arm at the side declined by 11°. The Simple Shoulder Test score improved by 5 points and the Constant score by 41 points, although the strength subscore did not rise significantly.

CONCLUSIONS

This study showed that it is anatomically feasible to use the pectoralis minor tendon as a graft to treat upper subscapularis lesions; the procedure is safe in terms of brachial plexus and musculocutaneous nerve injury; and pectoralis minor transfer can improve shoulder function and provide pain relief in patients with Lafosse grade III subscapularis tears, likely through a tenodesis effect, even in the presence of irreparable supraspinatus tears.

The Latarjet coracoid process transfer procedure: alterations in the neurovascular structures

BACKGROUND

The Latarjet coracoid process transfer procedure is an established, reliable treatment for glenoid deficiency associated with recurrent anterior shoulder instability, but changes in neurovascular anatomy resulting from the procedure are a concern. The purpose of our cadaveric study was to identify changes in the neurovascular anatomy after a Latarjet procedure.

MATERIALS AND METHODS

We obtained 4 paired, fresh-frozen cadaveric forequarters (8 shoulders) from the Maryland State Anatomy Board. In each shoulder, we preoperatively measured the distances from the midanterior glenoid rim to the musculocutaneous nerve, axillary nerve, and axillary artery in 2 directions (lateral to medial and superior to inferior) and with the arm in 2 positions (0° abduction/neutral rotation; 30° abduction/30° external rotation), for a total of 12 measurements. We then created a standardized bony defect in the anterior-inferior glenoid, reconstructed it with the Latarjet procedure, and repeated the same measurements. Two examiners independently took each measurement twice. Inter-rater reliability was adequate, allowing pre-Latarjet measurements to be combined, averaged, and compared with combined and averaged post-Latarjet measurements by using paired Student t tests (significance, P ≤ .05).

RESULTS

We found (1) significant differences in the location of the musculocutaneous nerve in the superior-to-inferior direction for both arm positions, (2) notably lax and consistently overlapping musculocutaneous and axillary nerves, and (3) an unchanged axillary artery location.

CONCLUSIONS

The Latarjet procedure resulted in consistent and clinically significant alterations in the anatomic relationships of the musculocutaneous and axillary nerves, which may make them vulnerable to injury during revision surgery.

Complications associated with open coracoid transfer procedures for shoulder instability

BACKGROUND

Interest has been maintained in the use of coracoid transfer procedures for recurrent shoulder instability despite the significant potential for serious complications. A comprehensive systematic review of the literature was performed to quantify and characterize the complication rate associated with these procedures to better inform practicing surgeons and their patients.

MATERIALS AND METHODS

Medline, Excerpta Medica Database (EMBASE), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases were searched for therapeutic studies published between 1985 and 2011. Data regarding complications was extracted from selected articles in a standardized manner. Complication rates were determined and expressed as percentages with 95% confidence intervals.

RESULTS

Included were 30 studies describing the results of 1658 coracoid transfer procedures. Repeat surgery was documented in 4.9% ± 1.0% of cases. Recurrent instability occurred in 6.0% ± 1.2%. Hardware complications occurred in 6.5% ± 1.3%. Collectively, the rate of graft nonunion, fibrous union, or postoperative graft migration was 10.1% ± 1.6%; graft osteolysis occurred in 1.6% ± 0.7%. There was a 1.2% ± 0.8% rate of nerve palsy. Surgical site infection occurred in 1.5% ± 0.7%. Intraoperative fractures occurred in 1.1 ± 0.6%.

CONCLUSION

Coracoid transfers for shoulder instability can improve shoulder stability with acceptable recurrence rates. They are challenging procedures associated with a broad range and significant incidence of complications. A detailed appreciation of anatomy and meticulous attention to technical detail, particularly graft placement, is key to reducing complications. These procedures may be best indicated in the setting of glenoid or humeral bony deficiency, although efficacy over open capsular procedures remains equivocal.

[Absence of the musculocutaneous nerve and its distribution from median nerve: About two cases and literature review]

Musculocutaneous nerve arises mostly from the lateral cord of brachial plexus. Nevertheless, variations have been reported and, among them: the total absence of musculocutaneous nerve (from 1.4 to 15%), the absence of its passage through the coracobrachial muscle, its variable level of penetration as measured from the tip of the coracoid process, and its communicating branches with the median nerve. We report two cases of unilateral musculocutaneous nerve absence in a 66-year-old male and a 95-year-old female cadavers, on the right and the left side, respectively. The nerve fibers normally coming from musculocutaneous nerve emerged from the median nerve. The knowledge of this anatomical variation is important specially when performing plexus bloc or Latarjet's procedure.

Irreducible shoulder dislocation - a word of caution

Anterior dislocation of shoulder is usually amenable to closed manipulation. Failure to achieve satisfactory reduction can be due to soft tissue or osseous interposition. We report a case of irreducible anterior shoulder dislocation with the interposition of the musculocutaneous nerve. This required open reduction and release of the musculocutaneous nerve; which was found to be further trapped by the torn long head of biceps.

Treatment of chronic glenoid defects in the setting of recurrent anterior shoulder instability: a systematic review

OBJECTIVE

The purpose is to systematically evaluate the literature regarding treatment of chronic glenoid bone defects in the setting of recurrent anterior shoulder instability to determine if, from an evidence-based outcomes approach, one technique may be recommended over the other.

METHODS

PubMed 1966-2009, Embase 1980-2009, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials databases were searched for human studies in English. Keywords were osseous glenoid defects, glenoid bone grafting, Latarjet procedure, iliac crest and glenoid defects, and glenoid rim fractures. Inclusion criteria were all articles evaluating chronic glenoid deficiency in the setting of recurrent anterior glenohumeral instability. Exclusion criteria were surgical techniques not reporting follow-up, glenoid rim fractures treated by open reduction internal fixation, and investigations not quantifying glenoid deficiency assessments.

RESULTS

Six articles met all inclusion and exclusion criteria. All articles were level IV (case series), most (5/6) were retrospective. Multiple techniques involving coracoid transfer and allograft or autograft reconstruction have been described for management of chronic glenoid deficiency. Lack of high level evidence in the form of prospective randomized trials limits our ability to recommend one technique over another. The 6 techniques reviewed here were all effective at preventing recurrent instability.

CONCLUSIONS

Chronic glenoid deficiency in the setting of recurrent anterior instability is an extremely challenging problem. There remains a lack of strong evidence guiding the surgeon in the decision-making process. Additional research is needed to optimize the preoperative glenoid defect assessment, further evaluate the reconstruction techniques, and follow the long-term effects of reconstruction on the development of glenohumeral arthrosis.

The role of arthroscopy in the revision of failed Latarjet procedures

Glenohumeral instability is an intrinsic pathological condition of the shoulder, owing to its ample range of mobility that predisposes this joint to a somewhat limited degree of stability. Several techniques have been employed for the treatment of instability. Among these, one is the Latarjet procedure, recommended for cases of substantial bone deficit on the humeral head or on the anterior region of the glenoid. Such technique gives generally good, long-term results, considering the low incidence of recurrence. However, potential complications such as glenohumeral arthrosis, absorption of the bone block, breakage, malpositioning or mobilization of the screws, infections, neurological or vascular complications can be serious. Moreover, as a result of further severe trauma, the shoulder can become again globally unstable. In such cases, the question arises of which technique to employ in surgical revision, since the Latarjet procedure determines substantial subversion of glenohumeral anatomy. The aim of the study was the analysis of arthroscopical treatment after failure of a Latarjet procedure and to describe the related definitive results. During the period between January 2000 and June 2007, we treated 17 patients (18 shoulders) using arthroscopy, following failure of an open Latarjet surgical procedure. One patient was operated bilaterally. Clinical revision according to the Constant Score, ROWE, ASES, UCLA and the VAS scale for pain evaluation was carried out during follow-up examination after an average period of 5 years and 9 months (min. 2 years-max. 9 years) from latest surgery. The system of evaluation according to the Constant Score indicated an average score of 78.4/100 at follow-up examination; UCLA indicated 27.2/35; ASES 99.6/120; ROWE 75.2/100. With regard to pain, the VAS Scale indicated an average score of 2.9/10. As criteria for relapse, we considered classic cases of dislocation and subluxations, or sprains with subluxation, and subjectively experienced apprehension and pain to a degree that seriously inhibited the patient's daily life. The incidence of relapse following the final surgical operation (taking into consideration both frank dislocations and subluxations) was 16.7%. At clinical revision, one patient showed dislocation due to relatively modest trauma approximately 1 year following the second surgery (5.6%). Episodes of subluxation or sprains continued in 2 shoulders (11.1% relapse). In 11 cases (61%), return to sports activities was achieved. Arthroscopy technique using anchors and sutures can, in selected cases, lead to satisfactory results, allowing, by means of minimal surgical invasion, identification and treatment also of intra-articular lesions, where associated.