Injury to the brachial plexus during Putti-Platt and Bristow procedures. A report of eight cases

Axillary and musculocutaneous neuropathies

This chapter covers axillary and musculocutaneous neuropathies, with a focus on clinically relevant anatomy, electrodiagnostic approaches, etiologic considerations, and management principles. Disorders of the lateral antebrachial cutaneous nerve, a derivative of the musculocutaneous nerve, are also reviewed. We emphasize the importance of objective findings, including the physical examination and electrodiagnostic evaluation in confirming the isolated involvement of each nerve which, along with the clinical history, informs etiologic considerations. Axillary and musculocutaneous neuropathies are both rare in isolation and most frequently occur in the setting of trauma. Less commonly encountered etiologies include external compression or entrapment, neoplastic involvement, or immune-mediated disorders including neuralgic amyotrophy, postsurgical inflammatory neuropathy, multifocal motor neuropathy, vasculitic neuropathy, and multifocal chronic inflammatory demyelinating polyradiculoneuropathy.

Common Focal Neuropathies in the Hospitalized Patient

Neuropathies are a common problem encountered by neurologist in the hospitalized setting. Nerve injury may occur secondary to compression, stretch, and direct trauma, among other causes. Common focal neuropathies include the ulnar, median, and radial nerve in the upper extremities and sciatic, peroneal, and femoral nerve in the lower extremities. Surgical and obstetric risk factors are especially important considerations in evaluation of patients with focal neuropathies. Treatment is either conservative therapy or surgery depending on the mechanism of injury and extent of recovery.

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.

Clinical and Radiographic Evaluation of Patients Operated by the Bristow-Latarjet Technique with a Minimum Follow-Up of 20 Years

Objective  To verify the results of 27 patients submitted to surgery from 1990 to 1997 by the Bristow-Latarjet technique for the treatment of anterior traumatic instability of the shoulder. The analysis included the possible complications, especially the appearance of arthropathy. Methods  The subjective clinical evaluation was performed through a questionnaire answered by the patients, and the objective evaluation was performed using the Rowe et al score. The radiographic evaluation was performed using the anteroposterior (true) incidence to detect signs of shoulder arthrosis, according to the classification of Samilson and Prieto, as well as the apical oblique and the Bernageau and Patte incidences to verify the consolidation of the bone graft, the position of the screw and of the graft, and signs of the release of the synthesis material. These evaluations were performed by two examiners at different times without interference between them. Results  In the subjective assessment of the patients, 93% were fully recovered, and, in the objective evaluation, the average was 95 points on the Rowe et al score. Complications related to coracoid placement were not found. The degree of arthropathy of the shoulders, according to the Samilson and Prieto classification, presented an average of seven mild cases, two moderate cases and one severe case. In total, 17 patients did not present arthropathy. Conclusion  Between the first and second evaluations, there was no change in the efficacy of the Bristow-Latarjet technique. The careful observation of the criteria of the technique was fundamental to avoid complications. The occurrence of arthropathy in the long term was not relevant in our evaluation. Based on the evidences of the present study, the surgical procedure alone is not the cause of the onset of the arthropathy, but the failure in its execution.

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.

Neurovascular Compression After the Latarjet Procedure

The Latarjet procedure is an established and effective option for the treatment of recurrent anterior shoulder instability. Symptomatic compression of the vasculature around the shoulder and adjacent brachial plexus is uncommon and may be difficult to diagnose and treat. The purpose of this report is to describe a patient with neurovascular compression of the axillary artery and brachial plexus after an open Latarjet procedure. This is the first known report of documented combined vascular and neurologic thoracic outlet syndrome after a Latarjet procedure. Evaluation of this suspected problem requires a detailed clinical examination and a dynamic angiogram to verify which neurovascular structures are compressed. Treatment includes decompression of the brachial plexus and axillary vasculature by releasing tethering scar tissue or the remaining pectoralis minor that is creating a constricting sling effect. An arthroscopic approach provides for a careful and specific decompression. Additionally, the authors provide a review of the literature for neurologic complications and management for these complications.

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.

Injury to the axillary nerve after reverse shoulder arthroplasty: an anatomical study

BACKGROUND

Subclinical neurological lesions after reverse shoulder arthroplasty are frequent, mainly those involving the axillary nerve. One of the major reported risk factors is postoperative lengthening of the arm. The purpose of this study was to evaluate the anatomical relationship between the axillary nerve and prosthetic components after reverse shoulder arthroplasty. The study hypothesis was that inferior overhang of the glenosphere relative to glenoid could put this nerve at risk.

MATERIAL AND METHODS

Eleven fresh frozen shoulder specimens were dissected after having undergone reverse shoulder arthroplasty using a classic deltopectoral approach.

RESULTS

The mean distance from the inferior border of the glenoid to the inferior edge of the glenosphere was 6.0±4.3mm (range, 1.0 to 16.2mm). The axillary nerve was never closer than 15mm to the glenosphere. The main anterior branch of the axillary nerve was in close contact with the posterior metaphysis or humeral prosthetic implant. The mean distance between the nerve and the humeral implants was 5.2±2.1mm (range, 2.0 to 8.1mm).

CONCLUSIONS

The proximity of the axillary nerve to the posterior metaphysis or humeral implants may be a risk factor for axillary nerve injury after reverse shoulder arthroplasty.

CLINICAL RELEVANCE

This study quantifies the proximity of the axillary nerve to the implant after reverse shoulder arthroplasty.

LEVEL OF EVIDENCE

Basic science study, cadaver study.

Iatrogenic nerve injuries during shoulder surgery

INTRODUCTION

The current literature indicates that neurologic injuries during shoulder surgery occur infrequently and result in little if any morbidity. The purpose of this study was to review one institution's experience treating patients with iatrogenic nerve injuries after shoulder surgery.

METHODS

A retrospective review of the records of patients evaluated in a brachial plexus specialty clinic from 2000 to 2010 identified twenty-six patients with iatrogenic nerve injury secondary to shoulder surgery. The records were reviewed to determine the operative procedure, time to presentation, findings on physical examination, treatment, and outcome.

RESULTS

The average age was forty-three years (range, seventeen to seventy-two years), and the average delay prior to referral was 5.4 months (range, one to fifteen months). Seven nerve injuries resulted from open procedures done to treat instability; nine, from arthroscopic surgery; four, from total shoulder arthroplasty; and six, from a combined open and arthroscopic operation. The injury occurred at the level of the brachial plexus in thirteen patients and at a terminal nerve branch in thirteen. Fifteen patients (58%) did not recover nerve function after observation and required surgical management. A structural nerve injury (laceration or suture entrapment) occurred in nine patients (35%), including eight of the thirteen who presented with a terminal nerve branch injury and one of the thirteen who presented with an injury at the level of the brachial plexus.

CONCLUSIONS

Nerve injuries occurring during shoulder surgery can produce severe morbidity and may require surgical management. Injuries at the level of a peripheral nerve are more likely to be surgically treatable than injuries of the brachial plexus. A high index of suspicion and early referral and evaluation should be considered when evaluating patients with iatrogenic neurologic deficits after shoulder surgery.

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 and re-operations after Bristow-Latarjet shoulder stabilization: a systematic review

BACKGROUND

Various methods of bony stabilization, including modifications of Bristow and Latarjet procedures, are considered gold-standard treatment for recurrent anterior shoulder instability but are associated with unique complications and risk of reoperation. The purpose of this study was to identify the prevalence of these complications. We hypothesized that the Bristow-Latarjet procedure would be a successful technique for treatment of shoulder instability but associated with a risk of recurrent postoperative instability, reoperation, and other complications.

METHODS

A systematic review of multiple medical databases included studies reporting outcomes with complication and reoperation rates following original or modified versions of the Bristow or Latarjet shoulder stabilization surgeries.

RESULTS

Forty-five studies were analyzed (1,904 shoulders) (all Level IV evidence). Most subjects were male (82%). The dominant shoulder was the operative shoulder in 64% of cases. Mean subject age was 25.8 years. Mean clinical follow-up was 6.8 years. Ninety percent of surgeries were done open; 9.3% were all-arthroscopic. Total complication rate was 30%. Recurrent anterior dislocation and subluxation rates were 2.9% and 5.8%, respectively. When reported, most dislocations occurred within the first year postoperatively (73%). Nearly 7% of patients required an unplanned reoperation following surgery.

CONCLUSION

Osseous stabilization shoulder surgery using original or modified Bristow and Latarjet procedures has a 30% complication rate. Rates of recurrent dislocation and reoperation were 2.9% and 7%, respectively. Mild loss of external rotation is common. Reoperation rates were lower following all-arthroscopic techniques. There was a greater loss of postoperative external rotation with all-arthroscopic 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.

Short-term complications of the Latarjet procedure

BACKGROUND

Although the results of the Latarjet procedure have been reported previously, there is little literature regarding the early complications of this procedure. The purpose of this study was to report our experience with the Latarjet procedure for glenohumeral instability and to highlight the initial complications that may occur following this procedure.

METHODS

Forty-seven patients (forty-eight shoulders) underwent the Latarjet procedure for anterior glenohumeral instability between January 2005 and January 2010. All shoulders had some osseous deficiency of the anterior glenoid rim or had undergone an unsuccessful prior soft-tissue Bankart repair. The minimum duration of patient follow-up was six months.

RESULTS

Forty-five shoulders were available for follow-up. The overall complication rate was 25% (twelve of the original forty-eight shoulders). Complications were divided into three groups: infection, recurrent glenohumeral instability, and neurologic injury. A superficial infection developed in three shoulders (6%); in all cases, the infection resolved following irrigation and debridement and administration of antibiotics for up to four weeks. Four shoulders (8%) developed recurrent glenohumeral instability; this occurred within eight months in two shoulders and at nineteen and forty-two months postoperatively in the other two. Five procedures (10%) resulted in a neurologic injury. Two of these involved the musculocutaneous nerve, one involved the radial nerve, and two involved the axillary nerve. The three musculocutaneous and radial nerve injuries involved sensory neurapraxia that resolved fully within two months. Both of the patients with axillary nerve dysfunction continued to have persistent sensory disturbances and one continued to have residual weakness that had not yet resolved fully at the time of the final follow-up.

CONCLUSIONS

The overall complication rate of 25% is higher than that reported in the literature. Although most of these complications resolved completely, two patients continued to have residual neurologic symptoms. Patients should be informed of the risk of complications associated with the Latarjet procedure, although most of the potential complications will resolve.

Anterior shoulder instability with Bristow procedure versus conjoined tendon transfer alone in a simple soft-tissue model

PURPOSE

We compared the Bristow procedure with a conjoined tendon transfer to investigate the role of the sling alone in restoring anterior translation in a simple soft-tissue instability model without bony defects.

METHODS

Ten matched cadaveric shoulder pairs were randomly assigned to receive a Bristow procedure or a conjoined tendon transfer alone. Specimens were tested in a simple soft-tissue model with low load simulating anterior translation of the glenohumeral joint. The conditions (intact, cut, and repaired) and treatments (Bristow and conjoined tendon transfer alone) were compared for anteroposterior translation.

RESULTS

Anterior translation increased from 3.4 +/- 0.6 mm (mean +/- SEM) to 12.0 +/- 1.3 mm after the cut and decreased to 5.2 +/- 0.7 mm with the Bristow procedure. Anterior translation increased from 2.8 +/- 0.4 mm to 12.2 +/- 1.9 mm after the cut and decreased to 4.9 +/- 0.5 mm after conjoined tendon transfer alone. Although the repair increased the stability of the glenohumeral joint as reflected in significantly decreased anterior translation, anterior translation in the repaired joint was significantly greater than that in the intact condition for both procedures (P < .05). There were no significant differences in anterior translation between the 2 treatments at any test stage.

CONCLUSIONS

There was no difference between the Bristow procedure and conjoined tendon transfer alone in restoring anteroposterior translation in a simple soft-tissue shoulder instability model with low load and no bony defect.

CLINICAL RELEVANCE

Further investigation of the described conjoined tendon procedure should be done to evaluate the procedure with significant bony defects.

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

PURPOSE

The aim of this study was first to define first the anatomical relationships between the musculocutaneous nerve and the coracobrachialis, and then the induced modifications of these relationships by a preglenoid transposition of the vertical part of the coracoid process.

MATERIALS AND METHODS

Twenty-one embalmed adult trunks and upper limb were dissected. First the coracobrachialis and the musculocutaneous nerve were identified through a deltopectoral approach. We measured the distances between the lateral cord of the brachial plexus and the entry point of the nerve, between the inferior tip of the tip of the coracoid process and the penetration of the nerve or its twigs, and finally the angle between the general axis of the coracobrachialis and the axis of the musculocutaneous nerve. The same measures were performed after the coracoid bone block abutment.

RESULTS

Proximal motor branches destined to the coracobrachialis varied from 0 to 3. Mean distance between the lateral cord of the brachial plexus and entry point of the nerve into the muscle was 47.2 mm before and 48.43 mm after the coracoid transfer. Mean angulations between the nerve and the muscle was 121 degrees before and 136 degrees after the transfer of the coracoid process. Mean distance between the inferior tip of the coracoid process and entry point of the nerve into the muscle was 55.7 mm, reduced to 48.6 mm after the coracoid transposition. Finally, the distance between the tip of the coracoid and the first motor twig entering the coracobrachialis was less than 50 mm in 75% of the cases with a mean value of 40.6 mm.

CONCLUSIONS

Lesion of the musculocutaneous nerve is a known complication of the coracoid bone block abutment procedure (Latarjet-Bristow). From this study we know that they are due to lengthening of the nerve and modification of the penetration angle of the nerve into the coracobrachialis. We also infer that some motor nerve destined to the coracobrachialis might be damaged during the proximal medial release of the muscle after the detachment of the pectoralis minor muscle.

Axillary nerve repair by triceps motor branch transfer through an axillary access: anatomical basis and clinical results

Object

Grafting or nerve transfers to the axillary nerve have been performed using a deltopectoral approach and/or a posterior arm approach. In this report, the surgical anatomy of the axillary nerve was studied with the goal of repairing the nerve through an axillary access.

Methods

The axillary nerve was bilaterally dissected in 10 embalmed cadavers to study its variations. Three patients with axillary nerve injuries then underwent surgical repair through an axillary access; the axillary nerve was repaired by transfer of the triceps long head motor branch.

Results

At the lateral margin of the subscapularis muscle, the axillary nerve was found in the center of a triangle bounded medially by the subscapular artery, laterally by the latissimus dorsi tendon, and cephalad by the posterior circumflex humeral artery. At the entrance of the quadrangular space, the axillary nerve divisions were loosely connected to each other, and could be clearly separated and correctly identified. Surgery for the axillary nerve repair through the axillary access was straightforward. Eighteen months after surgery, all three patients had recovered deltoid strength to a score of M4 on the Medical Research Council scale and had improved abduction strength by 50%. No deficit was evident in elbow extension.

Conclusions

The axillary nerve and its branches can be safely dissected and repaired by triceps motor nerve transfer through an axillary access.

Musculocutaneous nerve: Histotopographic study and clinical implications

Surgical reconstruction of severe brachial plexus injuries includes nerve grafting and neurotization techniques of the musculocutaneous nerve (MCN) to recover elbow flexion. In treating recurrent anterior shoulder instability, knowledge of the topography of the MCN is important for the margin of safety available during dissection. The present study evaluates the origin and course of the MCN and its branches, and their relationships to bone landmarks. Twelve unembalmed cadavers (50-82 years old) were dissected. A histological study of the MCN and the coracobrachialis muscle (CB) was also carried out. The mean distance (+/-SD) of the MCN from the coracoid process to the origin, points of entry to, and exit from the CB were 2.9 +/- 0.5 cm, 7.7 +/- 2.5 cm, and 11.6 +/- 0.8 cm, respectively. The first two findings were also validated during surgical approaches to the shoulder in 59 subjects. The mean distance of the MCN from the acromion to the origin, points of entry to, and exit from the CB were 6.4 +/- 0.3 cm, 7.7 +/- 0.8 cm, and 10.4 +/- 1.9 cm, respectively. The mean length of the MCN from its origin to the points of entry to and exit from the CB were 6.7 +/- 1.6 cm and 11.0 +/- 1.0 cm, respectively. The mean length of the MCN inside the muscle was 4.4 +/- 1.9 cm. The distance from the coracoid process to the point of entry to the CB and the length of the MCN inside the muscle were inversely related (P < 0.05). The distance from the coracoid process to the point of exit of the MCN was positively correlated with the length of the nerve within the CB (P < 0.05). Histology showed that, during the intramuscular course of the MCN, the epineurium is composed of 4-5 concentrically arranged lamina of connective tissue which shows different dispositions along the circumference of the nerve trunk. On the ventral and dorsal aspects of the nerve the lamina are closely packed, but on the medial and lateral sides they are separated by thin layers of adipose tissue. This uneven disposition of the adipose tissue gives the epineurium an oval profile in transverse section (mean circular factor 0.8). The arrangement of the fibroadipose tissue sheaths may be compared to a "telescope" and may allow compliance between variations of length of CB and the constant course of the MCN. Clinically, a decrease in this "sliding system" may expose the nerve to mechanical effects of muscle contraction, with the possibility of a compression syndrome.

Morphometric study of the nerves entering into the coracobrachialis muscle

The nerves entering into the coracobrachialis muscle are the musculocutaneous nerve (MC) and the nerve (usually consists of several thin branches) branches to the coracobrachialis. These thin branches enter the coracobrachialis proximal to the MC. The thin branches and the MC are susceptible to injury during coracoid process transfer. The purpose of this study is (1) to reveal the number and origin of the thin branches and (2) especially to report the morphometric information about the two distances between the coracoid process and the points where the first thin branch and the MC enter the coracobrachialis. These distances were named as the "distance T1" and the "distance D," respectively. Forty-two cadaver upper extremities were used and the distance between the coracoid process and the medial epicondyle of the humerus as the "arm length" was measured. The "ratio T1" was calculated by dividing the distance T1 by the arm length. The "ratio D" was calculated by dividing the distance D by the arm length. The number of the thin branches varied between one and four. In the most common type, there were two thin branches (45%). All of the thin branches originated from the MC. The mean distance T1, distance D and arm length were found as 41.5, 62 and 304.5 mm, respectively. The mean ratio T1 and ratio D were determined as 0.13 (approximately 1/8) and 0.20 (=1/5), respectively. The findings about the number and origin of the thin branches may contribute to the anatomy of the nerve to the coracobrachialis. The shoulder surgeon may calculate the predicted distance T1 and distance D of any upper extremity, dividing its arm length by eight and five, respectively.

Brachial plexopathies: classification, causes, and consequences

The brachial plexus, which is the most complex structure of the peripheral nervous system, supplies most of the upper extremity and shoulder. The high incidence of brachial plexopathies reflects its vulnerability to trauma and the tendency of disorders involving adjacent structures to affect it secondarily. The combination of anatomic, pathophysiologic, and neuromuscular knowledge with detailed clinical and ancillary study evaluations provides diagnostic and prognostic information that is important to clinical management. Since most brachial plexus disorders do not involve the entire brachial plexus but, rather, show a regional predilection, a regional approach to assessment of plexopathies is necessary.

Surgery about the coracoid: neurovascular structures at risk

PURPOSE

The purpose of this study was to examine the neurovascular structures at risk when performing surgery about the coracoid.

TYPE OF STUDY

Anatomic cadaveric study.

METHODS

Five fresh-frozen cadaveric shoulders were dissected to determine the dimensions of the coracoid and the distance from the coracoid to adjacent neurologic and vascular structures. The minimal distance from the coracoid tip to the axillary nerve, musculocutaneous nerve, the lateral cord of the brachial plexus, and the axillary artery was measured using a precision caliper. Similarly, the minimal distance from the base of the coracoid to the axillary nerve, musculocutaneous nerve, the lateral cord of the brachial plexus, and the axillary artery was measured.

RESULTS

The coracoid tip was defined as that portion of the bone that was distal to the "elbow" of the coracoid. Results showed that the mean width (medial-to-lateral dimension in the plane of the subscapularis tendon) of the coracoid tip was 15.9 +/- 2.2 mm, and the mean length of the coracoid tip was 22.7 +/- 4.5 mm. The mean thickness of the coracoid tip at its midportion was 10.4 +/- 1.5 mm. The portion of the coracoid tip which was closest to the neurovascular structures was the anteromedial portion of the coracoid tip. The distance from the anteromedial portion of the coracoid tip to the axillary nerve, the musculocutaneous nerve, the lateral cord, and the axillary artery was 30.3 +/- 3.9 mm, 33.0 +/- 6.2 mm, 28.5 +/- 4.4 mm, and 36.8 +/- 6.1 mm, respectively. Similarly, the portion of the base of the coracoid that was closest to the neurovascular structures was its anteromedial portion. The shortest distance from the anteromedial aspect of the base of the coracoid to the axillary nerve, the musculocutaneous nerve, the lateral cord, and the axillary artery was 29.3 +/- 5.6 mm, 36.5 +/- 6.1 mm, 36.6 +/- 6.2 mm, and 42.7 +/- 7.3 mm, respectively.

CONCLUSIONS

Procedures about the coracoid are relatively safe procedures. The lateral cord of the brachial plexus is at greatest risk during dissection about the tip of the coracoid, and the axillary nerve is at greatest risk during dissection about the base of the coracoid. The safety of arthroscopic coracoplasty or interval releases is further increased by the fact that most of the work is performed on the lateral aspect of the coracoid, which is even further away from the neurovascular structures.

CLINICAL RELEVANCE

This study quantifies the relative risk of injury to neurovascular structures during arthroscopic surgery about the coracoid.

Axillary nerve repair in 99 patients with 101 stretch injuries

Object. The purpose of this paper was to analyze outcomes in patients at the Louisiana State University Health Sciences Center (LSUHSC) who presented with contusion—stretch injuries to the axillary nerve. These injuries resulted from shoulder injury either with or without fracture/dislocation. Although recovery of deltoid function can occur spontaneously, this was not always the case.

Methods. Severe deficits persisting for several months led the patients to undergo surgery. Operative categories included isolated axillary palsy (56 procedures), combined axillary and suprascapular palsies (11 procedures), axillary and radial palsies (14 procedures), and axillary palsy with another deficit, usually infraclavicular plexus loss (20 procedures). Deltoid function was evaluated pre- and postoperatively by applying the LSUHSC grading system. An anterior infraclavicular approach was usually followed during surgery, but in three patients an additional posterior approach was used.

Axillary lesions usually began in the proximal portion of the posterior cord. Although several patients had distraction of the nerve, lesions in continuity were found in more than 90% of cases. Intraoperative nerve action potential (NAP) recordings were performed to determine the need for resection. Most repairs were made using grafts, although in three patients with relatively focal lesions suture was used.

When an NAP was recorded across the lesion and neurolysis was performed, recovery was judged to be a mean Grade 4 according to the LSUHSC in 30 cases. Recovery following suture repairs was a mean Grade 3.8, whereas recovery after 66 graft repairs was a mean Grade 3.7. In cases in which suprascapular palsies were associated with axillary injuries, the former recovered but the latter did not necessarily do so without surgery. If the radial nerve was also injured, recovery of the triceps and brachioradialis muscles and wrist extension was usually obtained, but it was far more difficult to reverse the loss of finger and thumb extension. Although few in number, complications did occur and they are important.

Conclusions. Operative exploration of axillary contusion—stretch lesions is worthwhile in carefully selected cases. If indicated by inspection and intraoperative electrical studies, nerve repair can lead to useful function.

Prevention of axillary nerve injury in anterior shoulder reconstructions: use of a subscapularis muscle-splitting technique and a review of the literature

BACKGROUND

Previous authors have suggested that the axillary nerve should be explored or palpated during all anterior shoulder stabilization procedures.

OBJECTIVE

The goal of this study was to document the axillary nerve injury rate in a cohort of patients who had undergone anterior shoulder stabilization without axillary nerve dissection.

HYPOTHESIS

Use of a subscapularis muscle-splitting approach by using a retractor along the scapular neck does not result in significant risk of injury to the axillary nerve, and exploration of the axillary nerve is not necessary using this approach.

STUDY DESIGN

Prospective cohort study.

METHODS

One hundred and twenty-eight anterior stabilizations were performed with a subscapularis muscle-splitting approach that has been previously described. In all cases a retractor was placed along the inferior scapular neck to protect the axillary nerve. The axillary nerve was not exposed or palpated in any case. All patients were evaluated on the 1st postoperative day and again within 10 days for symptoms of axillary nerve palsy, including sensory loss and return of muscle function. One patient (0.8%) had paresthesia in an axillary nerve distribution; recovery occurred without the need for electromyography or other interventions. There were no clinically detected cases of axillary nerve motor dysfunction.

CONCLUSIONS

Routine exposure of the axillary nerve is not necessary during anterior stabilization procedures using a subscapularis muscle-splitting approach if proper precautions are taken to protect the nerve. Other techniques of anterior stabilization may require exposure of the axillary nerve.

The anatomic relationship of the brachial plexus and axillary artery to the glenoid. Implications for anterior shoulder surgery

Iatrogenic brachial plexus injury is an uncommon but potentially severe complication of shoulder reconstruction for instability that involves dissection near the subscapularis muscle and potentially near the brachial plexus. We examined the relationship of the brachial plexus to the glenoid and the subscapularis muscle and evaluated the proximity of retractors used in anterior shoulder surgical procedures to the brachial plexus. Eight fresh-frozen cadaveric shoulders were exposed by a deltopectoral approach. The subscapularis muscle was split in the middle and dissected to reveal the capsule beneath it. The capsule was split at midline, and a Steinmann pin was placed in the equator of the glenoid rim under direct visualization. The distance from the glenoid rim to the brachial plexus was measured with calipers with the arm in 0 degrees, 60 degrees, and 90 degrees of abduction. The brachial plexus and axillary artery were within 2 cm of the glenoid rim, with the brachial plexus as close as 5 mm in some cases. There was no statistically significant change in the distance from the glenoid rim to the musculocutaneous nerve, axillary artery, medial cord, or posterior cord with the arm in various degrees of abduction. Retractors placed superficial to the subscapularis muscle or used along the scapular neck make contact with the brachial plexus in all positions tested.

Axillary nerve injury: diagnosis and treatment

Axillary nerve injury is infrequently diagnosed but is not a rare occurrence. Injury to the nerve may result from a traction force or blunt trauma applied to the shoulder. The most common zone of injury is just proximal to the quadrilateral space. Atraumatic causes of neuropathy include brachial neuritis and quadrilateral space syndrome. The vast majority of patients recover with non-operative treatment. Baseline electromyographic and nerve conduction studies should be obtained within 4 weeks after injury, with a follow-up evaluation at 12 weeks. If no clinical or electromyographic improvement is noted, surgery may be appropriate. The results of operative repair are best if surgery is performed within 3 to 6 months from the injury. Surgical options include neurolysis, nerve grafting, and neurotization. The results of repair of axillary nerve injuries have been good compared with treatment of other peripheral nerve lesions, due to the monofascicular composition of the nerve and the relatively short distance between the zone of injury and the motor end-plate.

Open shoulder instability surgery. Complications

Surgical stabilization of the shoulder can be a challenging procedure. Complications can and do occur, even in the hands of the most experienced surgeons. Emphasis must be placed on proper diagnosis, appropriate technique, and an understanding of potential complications to maximize the likelihood of a successful surgical outcome. The authors hope that this review helps to outline the complications that can occur with open instability surgery. Only by understanding the complications associated with the procedures performed can surgeons hope to decrease the frequency of their occurrence.

Neurologic complications of surgery for anterior shoulder instability

Two-hundred eighty-two patients underwent anterior reconstruction for recurrent glenohumeral instability between 1981 and 1991. Twenty-three patients (8.2%) had a neurologic deficit after surgery. Seven had sensory disturbances only; 16 had sensorimotor neuropathies (8 having multiple deficits designated as a diffuse plexopathy and 8 having a more defined deficit in 1 or 2 cords or peripheral nerves). Complete resolution occurred in 18 of the 23 patients. Four patients had a residual deficit (1 patient was lost to follow-up). Three had persistent sensory disturbances; 1 had permanent biceps weakness. None of these patients underwent surgical exploration. Older age (P = .045) and a Bankart lesion (P = .029) were associated with a neurologic complication. At an average follow-up of 8.7 years, 252 patients responded to a questionnaire regarding shoulder outcome, including 20 of the 23 patients with nerve injuries. The difference in the median Rowe score of those with and without nerve injury was not significant (P = .072). Neurologic injuries after anterior shoulder surgery presumably arise as a result of traction. The prognosis for neurologic recovery is generally good. Neurologic injury did not interfere with the outcome of the stabilization procedure.

The relationship of the axillary nerve to arthroscopically placed capsulolabral sutures. An anatomic study

Ten cadaveric shoulders (mean donor age, 60.5 years) underwent arthroscopic placement of capsulolabral sutures as performed during arthroscopic reconstruction for shoulder instability. In relation to the glenoid face, the sutures were placed anterior, anteroinferior, inferior, posteroinferior, and posterior. All sutures entered the capsule approximately 1 cm away from the glenoid and exited beneath the labrum, and were tied using arthroscopic knot-typing techniques. The shoulders were frozen in the lateral arthroscopic position of approximately 45 degrees of abduction and 20 degrees of flexion and sectioned in the plane of the glenohumeral joint. The axillary nerve was then dissected, and the average distance from the nerve to each suture was found to be 16.7 mm at the anterior position, 12.5 mm at the anteroinferior position, 14.4 mm at the inferior position, 24.1 mm at the posteroinferior position, and 32.3 mm at the posterior position. In no specimen was any suture closer to the axillary nerve than 7 mm. We noted a statistically significant trend for the nerve to lie closest to the anteroinferior suture and gradually recede from the remaining sutures lying more posteriorly. This anatomic study is the first to demonstrate a relatively safe margin for arthroscopic suture placement between the capsule and axillary nerve when these sutures are placed approximately 1 cm from the glenoid rim.

Iatrogenic nerve injuries

Iatrogenic nerve injuries are an undesired byproduct of the practice of medicine and have been so since antiquity. The majority of such injuries occur perioperatively, and are, therefore, attributed to surgeons and anesthesiologists. Nonetheless, the members of almost every clinical specialty are at risk to some degree. Iatrogenic nerve injuries can affect almost any portion of the peripheral nervous system, and can result from many different causes. This article reviews many of the more common iatrogenic nerve lesions.

Neurologic complications after total shoulder arthroplasty

Three hundred sixty-eight patients underwent 417 total shoulder arthroplasties between 1975 and 1989. Seventeen patients with 18 operated shoulders had a neurologic deficit after surgery. Osteoarthritis and rheumatoid arthritis were the most common diagnoses. Twelve patients (13 shoulders) had neurologic deficits localized to the brachial plexus; the upper and middle trunks were most commonly affected. Three patients had idiopathic brachial plexopathy. One patient had an exacerbation of preexisting dysesthesias in the lower trunk/medial cord distribution. Another patient had a median neuropathy at the wrist. Four patients had lesions that interfered significantly with shoulder rehabilitation and general activity; six had lesions that temporarily interfered with their scheduled rehabilitation program. All but two of these patients were monitored to a point of maximum improvement. Neurologic recovery at 1 year was graded as good in 11 shoulders and fair in five shoulders. The long deltopectoral approach leaving the deltoid attached to the clavicle and acromion was found to be significant in the development of a postoperative neurologic complication (p = 0.003). Use of methotrexate was also significant (p < 0.0001). A correlation was found between operative time and postarthroplasty neurologic complication (p = 0.02), with shorter operative times being associated with more neurologic complications. No other statistically significant risk factors were identified. In most cases the presumed mechanism of injury was traction on the plexus occurring during the operation. In most cases the prognosis for neurologic recovery was good. In this series neurologic injury after total shoulder arthroplasty did not interfere with the long-term outcome of the arthroplasty itself.

Shoulder arthroscopy and nerve injury: pitfalls and prevention

Shoulder arthroscopy has become a very useful diagnostic and therapeutic modality. Unfortunately, like many other invasive procedures it can have complications. One of the most worrisome complications, for both the patient and surgeon, is that of nerve injury. Nerve injury during shoulder arthroscopy is often a transient phenomenon although a more severe injury has been documented. We review much of the literature on this subject and discuss some of the many pitfalls and preventative strategies that have been reported.

An anatomic study of the subscapularis tendon and myotendinous junction

The subscapularis muscle and tendon were studied in 25 cadaveric specimens. The subscaputaris insertion into the proximal humerus and its musculolendinous junction was defined. We found that the subscapularis muscle had a gradual formation of the musculotendinous junction and, in contrast to classical descriptions, inserted into the humerus as both tendon and muscle. The musculotendinous junction was fully formed 2 cm from the lesser tuberosity. The superior 60% of the muscle's insertion inserted into the lesser tuberosity as tendon. The remaining insertion consisted of muscle and was below the lesser tuberosity. The anterior humeral circumflex vessels and the axillary nerve marked the inferior aspect of the subscapularis muscle at the anterior aspect of the quadrangular space. The vessels then coursed laterally and superiorly onto the anterior surface of the muscle insertion coursing over the division between the tendinous and muscular portions. Proper identification of these relationships can prevent complications in shoulder surgery.

Long-term followup of the modified Bristow procedure

A total of 86 modified Bristow procedures were performed for anterior shoulder instability between 1975 and 1987. Followup on 79 shoulders (92%) was obtained at an average postoperative time of 8.6 years. The redislocation rate was 4%. Average motion loss was 5 degrees of internal rotation and 9 degrees of external rotation. Fifteen percent of the patients examined expressed mild apprehension with the shoulder abducted and externally rotated. Radiographic bone union of the coracoid transplant was noted in 82% of patients. Additional surgical procedures were required in 14% of patients. Seventy-three percent of the reoperations were for screw removal because of persistent shoulder pain. The average subjective shoulder function was rated at 86% of preinjury level. All throwing athletes were able to return to throwing, although 54% of the patients with dominant shoulder involvement noted a decrease in throwing velocity. Ninety-seven percent of the patients rated their results as good or excellent.