Surgery about the coracoid: neurovascular structures at risk

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.

Distal Clavicle Autograft Versus Traditional and Congruent Arc Latarjet Procedures: A Comparison of Surface Area and Glenoid Apposition With 3-Dimensional Computed Tomography and 3-Dimensional Magnetic Resonance Imaging

BACKGROUND

Limited studies have compared graft-glenoid apposition and glenoid augmentation area between the Latarjet procedure and distal clavicle graft in glenohumeral stabilization. Additionally, preoperative planning is typically performed using computed tomography (CT), and few studies have used 3-dimensional (3D) magnetic resonance imaging (MRI) reformations to assess graft dimensions.

PURPOSE

The purpose of this study was 2-fold: (1) to compare bony apposition, glenoid augmentation, and graft width among coracoid and distal clavicle bony augmentation techniques and (2) to determine the viability of 3D MRI to assess bone graft dimensions.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 24 patients with recurrent glenohumeral instability and bone loss were included in this study. 3D CT and 3D MRI reformations were utilized to measure pertinent dimensions for 5 orientations of coracoid and distal clavicle autografts: (1) standard Latarjet procedure (SLJ), (2) congruent arc Latarjet procedure (CLJ), (3) distal clavicle attached by its posterior surface (DCP), (4) distal clavicle attached by its inferior surface (DCI), and (5) distal clavicle attached by its resected end (DCR). Glenoid augmentation was defined as the graft surface area contributing to the glenoid. Bone-on-bone apposition was defined as the graft-glenoid contact area for bone healing potential, and graft width was pertinent for fixation technique. Glenoid bone loss ranged from 0% to 34%. Paired t tests were used to compare graft sizes between patients and compare 3D CT versus 3D MRI measurements.

RESULTS

The CLJ had the largest graft surface area (mean, 318.41 ± 74.44 mm²), while the SLJ displayed the most bone-on-bone apposition (mean, 318.41 ± 74.44 mm²). The DCI had the largest graft width (mean, 20.62 ± 3.93 mm). Paired t tests revealed no significant differences between the Latarjet techniques, whereas distal clavicle grafts varied significantly with orientation. All 3D CT and 3D MRI measurements were within 1 mm of each other, and only 2 demonstrated a statistically significant difference (coracoid width: 13.03 vs 13.98 mm, respectively [P = .010]; distal clavicle thickness: 9.69 vs 10.77 mm, respectively [P = .002]). 3D CT and 3D MRI measurements demonstrated a strong positive correlation (r > 0.6 and P < .001 for all dimensions).

CONCLUSION

Glenoid augmentation, bony apposition, and graft width varied with coracoid or distal clavicle graft type and orientation. Differences between 3D CT and 3D MRI were small and likely not clinically significant.

CLINICAL RELEVANCE

3D MRI is a viable method for preoperative planning and graft selection in glenoid bone loss.

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.

Comparing the Anatomical Landmarks Versus the Coracoid-Based Landmarks Techniques for Coracoclavicular Stabilization After High-Grade Acromioclavicular Injury: A Biomechanical Study

BACKGROUND

In acute high-grade acromioclavicular (AC) joint injuries, the aim of treatment is robust reduction and stabilization of the joint. The anatomical landmarks method is most commonly used for stabilization, but loss of reduction often occurs because of the suture tunnels.

PURPOSE/HYPOTHESIS

The purpose was to evaluate and compare the stability of coracoclavicular (CC) stabilization using the anatomical landmarks and coracoid-based landmarks techniques in treating a high-grade AC joint injury. It was hypothesized that stabilization using coracoid-based landmarks would provide better stability.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty fresh-frozen cadaveric shoulders (8 male and 2 female pairs) were randomized into 2 operative technique groups: 10 shoulders in the anatomical landmarks group and 10 shoulders in the coracoid-based landmarks group. The CC ligaments and AC capsule were cut at the midlevel, and CC stabilization and AC capsule repair were performed. For the anatomical landmarks technique, two 2.5-mm clavicular tunnels were created at 25 and 45 mm from the AC joint, while for the coracoid-based landmarks technique, two 2.5-mm clavicular tunnels were drilled using the medial and lateral borders of the coracoid base to choose the tunnel sites. Before injury creation and after stabilization, each shoulder underwent a loading force of 70 N in the superior and anteroposterior directions, and the displacement distance and stiffness were compared between the 2 techniques using the paired t test.

RESULTS

The mean difference in displacement before and after stabilization was higher in the anatomical landmarks technique than the coracoid-based landmarks technique (1.82 ± 3.52 vs -0.18 ± 4.78 mm in the superior direction and 7.47 ± 9.35 vs 1.76 ± 3.91 mm in the anteroposterior direction), but none of the differences in displacement or stiffness were statistically significant between the groups.

CONCLUSION

No significant biomechanical differences in displacement or stiffness were seen between the anatomical landmarks technique and the coracoid-based landmarks technique.

CLINICAL RELEVANCE

Either stabilization technique can be utilized for repair of the CC ligaments in an acute AC injury setting.

Clinical and radiologic outcomes of the modified phemister procedure with coracoclavicular ligament augmentation using mersilene tape versus hook plate fixation for acute acromioclavicular joint dislocation

Background

The clinical superiority of surgical treatment for acromioclavicular (AC) joint dislocation remains controversial. The aim of this study was to compare the clinical and radiological outcomes of the modified Phemister procedure with CC ligament augmentation using Mersilene tape to those of hook plate fixation for acute AC joint dislocation.

Methods

In this study, patients who received modified Phemister surgery with CC ligament augmentation using Mersilene tape (PM group) or hook plate fixation (HK group) for acute unstable AC joint dislocation with a minimum 5-year follow-up period were retrospectively reviewed. The clinical outcomes were evaluated according to blood loss during surgery, surgical duration, visual analogue scale (VAS), Constant-Murley score (CMS), University of California at Los Angeles (UCLA) shoulder rating scale, and the occurrence of complications. Radiological outcomes were assessed from radiographs according to multiple parameters, including CC distance maintenance, acromion osteolysis, and the presence of distal clavicle osteolysis.

Results

A total of 35 patients completed follow-up for more than 5 years and were analyzed in this study (mean = 74.08 months). There were 18 patients in the PM group and 17 in the HK group. The PM group exhibited similar improvement in functional outcome to the HK group. Regarding radiological outcomes, the HK group had a superior performance in terms of CC distance maintenance, of statistical significance (CCDR: 94.29 ± 7.01% versus 111.00 ± 7.69%, p < 0.001) after a one-year follow-up period. However, there were 4 cases of acromion osteolysis and 2 cases of distal clavicle osteolysis in the HK group.

Conclusion

Hook plate fixation was found to be superior to the modified Phemister technique with CC ligament augmentation using Mersilene tape in terms of CC distance maintenance, but there was no significant difference in the functional outcome after 5 years of follow-up. Both surgical methods are reliable options for the treatment of acute AC joint dislocation. Modified Phemister surgery with CC ligament augmentation using Mersilene tape is a relatively lower-cost option for acute AC joint dislocation without the need of a second surgery for implant removal.

[Treatment of subscapularis tendon lesions]

The further development of minimally invasive techniques in recent years, enables adequate intraoperative visualization, mobilization and stable reconstruction even of larger subscapularis tears resulting in good to excellent clinical and structural results. Chronic tears of the subscapularis tendon with high grade muscle atrophy and advanced fatty infiltration can be treated with a muscle tendon transfer (e.g. pectoralis major or latissimus dorsi transfer). If pseudoparalysis and/or signs of anterosuperior decentration of the humeral head or defect arthropathy are present, in most cases a reverse shoulder arthroplasty represents the only surgical option.

Effect of Preoperative MRI Coracoid Dimensions on Postoperative Outcomes of Latarjet Treatment for Anterior Shoulder Instability

Background:

Preoperative coracoid dimensions may affect the size of the bone graft transferred to the glenoid rim and thus the postoperative outcomes of Latarjet coracoid transfer.

Purpose:

To determine the effect of coracoid length and width as measured on preoperative magnetic resonance imaging (MRI) on outcomes after Latarjet treatment of anterior shoulder instability.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included were patients who underwent primary Latarjet surgery between 2009 and 2019 and had preoperative MRI scans and minimum 2-year postoperative outcomes. Longitudinal coracoid length was measured on axial MRI sequences as the distance from the coracoclavicular ligament insertion to the distal tip. Comparisons were made between shorter and longer coracoids and between narrower and wider coracoids. The outcomes of interest were recurrent instability, reoperation, complications, return to sport (RTS), and American Shoulder and Elbow Surgeons (ASES) score. Independent-samples t test, Mann-Whitney test, chi-square test, and Fisher exact test were used to compare outcomes between groups, and univariate correlation coefficients were calculated to evaluate the relationships between demographics and coracoid dimensions.

Results:

Overall, 56 patients were included (mean age, 28.4 years). The mean ± SD coracoid length was 21.6 ± 2.4 mm and width 10.0 ± 1.0 mm. Relative to patients with a longer coracoid (≥22 mm; n = 26), patients with a shorter coracoid (<22 mm; n = 30) had similar rates of recurrent instability (shorter vs longer; 6.7% vs 3.8%), complications (10.0% vs 15.4%), reoperation (3.3% vs 7.7%), and RTS (76.5% vs 58.8%) and similar postoperative ASES scores (85.0 vs 81.6) ( P ≥ .05 for all). Likewise, relative to patients with a wider coracoid (≥10 mm; n = 27), patients with a narrower coracoid (<10 mm; n = 29) had similar prevalences of recurrent instability (narrower vs wider; 6.9% vs 3.7%), complications (17.2% vs 7.4%), reoperation (3.5% vs 7.4%), and RTS (66.7% vs 68.4%) and similar postoperative ASES scores (87.1 vs 80.0) ( P ≥ .05 for all).

Conclusion:

Patients undergoing Latarjet coracoid transfer had similar postoperative outcomes regardless of preoperative coracoid dimensions. These findings should be confirmed in a larger cohort before further clinical recommendations are made.

Outcome following management of unstable lateral end clavicle fractures with locking plate and coracoid anchor augmentation

BACKGROUND

Management of complex lateral end clavicle fractures with coraco-clavicular ligament disruption can be challenging.

METHODS

We prospectively analysed 19 (17 M:2F) patients from January 2014 to June 2016. Six patients had intra-articular fractures (Edinburgh-3B2) and the remaining were extra-articular (3B1). All patients had open reduction internal fixation with lateral end locking plate augmented with a coracoid anchor. All patients were evaluated at the final follow-up by American Shoulder and Elbow Surgeon score (ASES), Disabilities of the Arm, Shoulder and Hand (DASH), Oxford Shoulder Score (OSS), return to work, sports and radiographs.

RESULTS

At a mean follow-up of 54 months (range 37-64), 19 patients were available for analysis. Mean age of patients was 34 years (range 24-65). At final follow-up DASH score was 1.66 (range 0-5); ASES score was 98.14 (93.3-100) and OSS was 46.6 (42-48). There was no difference in the functional outcome between 3B1 and 3B2 fractures (DASH - p(0.51); ASES - p(0.44); OSS - p(0.69)). All patients returned to preinjury level of function, sports and work. Five patients needed implant removal and three developed capsulitis that resolved with conservative treatment.

CONCLUSION

Locking plate fixation, augmented with coracoid anchor is an effective option in the management of these complex injuries. The need for implant removal is reduced (26%) and there is no difference in the functional outcome between 3B1 and 3B2 fractures.

Neurological Complications Following Arthroscopic and Related Sports Surgery: Prevention, Work-up, and Treatment

Arthroscopy of the shoulder, elbow, hip, and knee has become increasingly utilized due to continued advancements in technique, training, and instrumentation. In addition, arthroscopy is generally safe and effective in the utilization of joint preservation surgical techniques. The arthroscopist must utilize a thorough understanding of the surgical anatomy, detailed care with patient positioning, and safe instrumentation portals to prevent associated neurological injury. In the event of postoperative neurological complications, the physician must carefully document the patient history and physical examination while considering the utilization of additional imaging, testing, or surgical nerve exploration with a specialized team depending upon the severity of neurological injury. In this review, we discuss the prevention, evaluation, and treatment of neurological complications related for arthroscopic procedures of the shoulder, elbow, hip, and knee.

Comparison of the Coracoid, Distal Clavicle, and Scapular Spine for Autograft Augmentation of Glenoid Bone Loss: A Radiologic and Cadaveric Assessment

BACKGROUND

Glenohumeral instability caused by bone loss requires adequate bony restoration for successful surgical stabilization. Coracoid transfer has been the gold standard bone graft; however, it has high complication rates. Alternative autologous free bone grafts, which include the distal clavicle and scapular spine, have been suggested.

STUDY DESIGN

Controlled laboratory study.

PURPOSE

The purpose of this study was to determine the percentage of glenoid bone loss (GBL) restored via coracoid, distal clavicle, and scapular spine bone grafts using a patient cohort and a cadaveric evaluation.

METHODS

Autologous bone graft dimensions from a traditional Latarjet, congruent arc Latarjet, distal clavicle, and scapular spine were measured in a 2-part study using 52 computed tomography (CT) scans and 10 unmatched cadaveric specimens. The amount of GBL restored using each graft was calculated by comparing the graft thickness with the glenoid diameter.

RESULTS

Using CT measurements, we found the mean percentage of glenoid restoration for each graft was 49.5% ± 6.7% (traditional Latarjet), 45.1% ± 4.9% (congruent arc Latarjet), 42.2% ± 7.7% (distal clavicle), and 26.2% ± 8.1% (scapular spine). Using cadaveric measurements, we found the mean percentage of glenoid restoration for each graft was 40.2% ± 5.0% (traditional Latarjet), 53.4% ± 4.7% (congruent arc Latarjet), 45.6% ± 8.4% (distal clavicle), and 28.2% ± 7.7% (scapular spine). With 10% GBL, 100% of the coracoid and distal clavicle grafts, as well as 88% of scapular spine grafts, could restore the defect (P < .001). With 20% GBL, 100% of the coracoid and distal clavicle grafts but only 66% of scapular spine grafts could restore the defect (P < .001). With 30% GBL, 100% of coracoid grafts, 98% of distal clavicle grafts, and 28% of scapular spine grafts could restore the defect (P < .001). With 40% GBL, a significant difference was identified (P = .001), as most coracoid grafts still provided adequate restoration (congruent arc Latarjet, 82.7%; traditional Latarjet, 76.9%), but distal clavicle grafts were markedly reduced, with only 51.9% of grafts maintaining sufficient dimensions.

CONCLUSIONS

The coracoid and distal clavicle grafts reliably restored up to 30% GBL in nearly all patients. The coracoid was the only graft that could reliably restore up to 40% GBL.

CLINICAL RELEVANCE

With "subcritical" GBL (>13.5%), all autologous bone grafts can be used to adequately restore the bony defect. However, with "critical" GBL (≥20%), only the coracoid and distal clavicle can reliably restore the bony defect.

Computed Tomography-Based Preoperative Planning Provides a Pathology and Morphology-Specific Approach to Glenohumeral Instability With Bone Loss

PURPOSE

To use computed tomography (CT) to determine a reproducible method of coracoid measurement to compare the ability of the classic Latarjet technique and the congruent arc modification (CAM) to restore native glenoid diameter and to develop a preoperative planning algorithm for glenoid restoration with a goal of achieving an on-track shoulder.

METHODS

Coracoid dimensions were measured on multiplanar reconstructed shoulder CT scans of patients aged 18 to 45 years obtained between December 1, 2019, and March 13, 2020. Patients were excluded if CT demonstrated osteophyte formation, glenoid dysplasia, coracoid fracture, or tumor. The proportion of glenoid diameter able to be restored using classic Latarjet technique and CAM were calculated. A treatment algorithm was proposed considering the amount of bone loss present and coracoid dimensions.

RESULTS

Coracoid dimensions of 117 consecutive patients were measured and varied considerably (length: 17.5-31.8 mm, width: 9.1-20.5 mm, thickness: 6.1-15.7 mm). While most patients had harvestable coracoid length ≥20 mm (male: 96.3% vs female: 94.4%, P = .65), only 27.8% of female patients had coracoid thickness ≥10 mm. When comparing Latarjet techniques, there was no difference in the proportion of patients in whom 30% glenoid diameter could be fully restored, but CAM was able to restore at least 35% in more male and female patients (98.8% vs 79.0% and 100% vs 61.1%, respectively, P = .00001). Intra- and inter-rater reliability was excellent ( intraclass correlation coefficient ≥0.950 for all dimensions).

CONCLUSIONS

We describe a reliable method of measuring coracoid dimensions for preoperative planning of glenoid restoration. The classic Latarjet technique reliably restores the glenoid anteroposterior diameter with bone loss of up to 30%. The majority of female patients have coracoid thickness <10 mm, which may increase the risk of graft fracture when using CAM. The decision to use the classic Latarjet technique or CAM considers each individual's glenoid and coracoid dimensions with a goal of achieving an on-track shoulder.

CLINICAL RELEVANCE

Our reliable method of coracoid measurement demonstrated the differing abilities of the classic Latarjet and CAM to restore the native glenoid diameter. An evidence-based algorithm using these measurements was developed to assist in preoperative planning for glenohumeral instability in the setting of bone loss, with a goal of achieving an on-track shoulder. Alternative techniques may be considered if an on-track shoulder cannot be achieved with Latarjet.

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.

Failure of coracoid bone-block

The rate of recurrence of anterior unidirectional instability is lower after coracoid bone-block than with other techniques, even if failures still occur with this difficult procedure. Failure may consist in recurrent instability (dislocation, subluxation, unstable painful shoulder) or despite absence of obvious clinical signs, in radiologic failure (non-union, fracture), biologic failure (osteolysis) or infection, all of which may require revision surgery or lead to late instability or subclinical chronic apprehension. Clinical, X-ray and CT assessment identifies the type of failure and may lead to a second surgery being discussed with the patient according to functional demand. Technical error is often implicated and is generally due to deficient coracoid preparation, insufficient conjoint and coracoid tendon release or problems of positioning and fixing the bone-block on the glenoid. There are 2 types of revision surgery. Iliac bone-block involves the same demands as coracoid bone-block; it stabilises the shoulder and provides very good functional results. Although less effective, anterior capsule repair can also stabilise the shoulder when associated to posterior Hill-Sachs lesion remplissage by infraspinatus tenodesis. Osteoarthritis of the shoulder may set in after any surgical revision and impair the result.

The Shoulder Trans-pectoralis Arthroscopic Portal Is a Safe Approach to the Arthroscopic Latarjet Procedure: A Cadaveric Analysis

PURPOSE

To assess the proximity of neurovascular structures in a layered approach during medial portal placement and determine standardized measurements for establishing a portal medial to the coracoid used in arthroscopic Latarjet-type procedures.

METHODS

Twelve shoulders (6 right and 6 left) in 6 fresh frozen cadaveric torsos were mounted in the modified beach-chair position. A standard posterior portal and 3 anterior portals-central, lateral, and medial-were used. A long spinal needle was placed along the path of the medial portal to the lateral tip of the coracoid, superficial to the conjoined tendon and pectoralis minor. A second long spinal needle was directed toward the medial base of the coracoid, penetrating the pectoralis minor. Superficial and deep plane dissections were performed, and distances to surrounding neurovascular structures were recorded.

RESULTS

In the superficial plane, the cephalic vein and lateral pectoral nerve were located a mean distance (± standard deviation) of 4.6 ± 1.9 mm and 9.4 ± 2.6 mm from the spinal needle, respectively. In the deep plane, the axillary nerve was 24.9 ± 7.4 mm from the needle; the lateral cord of the brachial plexus, 25.5 ± 8.1 mm; the axillary artery, 34.1 ± 6.0 mm; and the musculocutaneous nerve, 42.2 ± 9.2 mm. The portal was consistently established 45.0 to 50.0 mm distal and 30.0 to 35.0 mm medial to the coracoid, which was a minimum distance of 10 mm to the lateral pectoral nerve.

CONCLUSIONS

In a cadaveric model, the creation of a medial trans-pectoralis major portal used in the arthroscopic Bankart-Bristow-Latarjet procedure can avoid compromise of vital neurovascular structures, alleviating concerns of creating a portal medial to the coracoid. Portal placement 45.0 to 50.0 mm distal and 30.0 to 35.0 mm medial to the palpable tip of the coracoid process may be a safe approach to perform the arthroscopic Bankart-Bristow-Latarjet procedure.

CLINICAL RELEVANCE

Creation of a portal medial to the level of the coracoid may pose a risk to neurovascular structures. This cadaveric study establishes a working zone for medial trans-pectoralis portal placement, which avoids vital neurovascular structures, and provides standardized measurements for establishing this portal for use in the arthroscopic Bankart-Bristow-Latarjet procedure.

A guideline for screw fixation of coracoid process base fracture by 3D simulation

BACKGROUND

Fractures of the base of the coracoid process are relatively rare, but an increasing number of studies have reported using screws to fix coracoid process base fractures. This study was performed to simulate the surgical procedure and obtain the ideal diameter, length, insertion point and angle of the screw from a 3-D axial perspective in Chinese patients.

METHODS

We randomly collected right scapula computed tomography (CT) scans from 100 adults. DICOM-formatted CT scan images were imported into Mimics software. A 3D digital model of the right scapula was established. Two virtual cylinders representing two screws were placed from the top of the coracoid process to the neck of the scapula and across the base of the coracoid process to fix the base of the coracoid process. The largest secure diameters and lengths of the virtual screws were measured. The positions of the insertion points and the directions of the screws were also examined.

RESULTS

The screw insertion safe zone can exhibit an irregular fusiform shape according to the reconstructed scapula model. The mean maximum diameters of the medial and lateral screws were 7.08 ± 1.19 mm and 7.34 ± 1.11 mm, respectively. The mean maximum lengths of the medial and lateral screws were 43.11 ± 6.31 mm and 48.16 ± 6.94 mm, respectively. A screw insertion corridor with a diameter of at least 4.5 mm was found in all patients. We found sex-dependent differences in the mean maximum diameters and maximum lengths of the two screws. The positions of the two insertion points were statistically different across sexes.

CONCLUSIONS

The study provides a valuable guideline for determining the largest secure corridor for two screws in fixing a fracture at the base of the coracoid process. For ideal screw placement, we suggest individualised preoperative 3D reconstruction simulations. Further biomechanical studies are needed to verify the function of the screws.

Risk of Iatrogenic Axillary Nerve Injury During Acromioclavicular Joint Reconstruction

Anatomical reconstruction of the coracoclavicular ligaments involves drilling the base of the coracoid or looping a graft around it, placing the axillary nerve at risk for injury. Rockwood type V acromioclavicular (AC) separation injuries involve disruption of the AC joint capsule and coracoclavicular ligaments, resulting in inferomedial displacement of the scapulohumeral complex and alteration of the normal anatomical relations of the shoulder girdle structures. This study evaluated the effect of Rockwood type V AC separation on the anatomical relation of the axillary nerve to the coracoid base. Ten shoulders of 6 adult human cadavers were dissected to determine the dimensions of the coracoid. A digital caliper was used to measure the coracoclavicular distance and the minimal distance between the coracoid base and the axillary nerve. A Rockwood type V AC separation was created by transecting the AC joint capsule and coracoclavicular ligaments, and applying 15 kg of longitudinal tension to the upper extremity. Changes in the distance between the coracoid base and the axillary nerve were measured. Mean width, length, and thickness of the coracoid was 15.05±0.93 mm, 23.1±1.75 mm, and 11.88±1.33 mm, respectively. Mean distance between the coracoid base and the axillary nerve was 26.0±3.9 mm. After simulated Rockwood type V AC separation, mean distance was 22.0±3.4 mm; this difference was statistically significant (P=.0263; 95% CI, 2.0-5.9 mm). The axillary nerve is closer to the coracoid base during simulated Rockwood type V AC separation than previously reported in the orthopedic literature. Anatomical reconstruction of the coracoclavicular ligaments for Rockwood type V AC separation presents a higher risk for axillary nerve iatrogenic injury than previously reported. [Orthopedics. 2021;44(1):e68-e72.].

How close is the axillary nerve to the inferior glenoid? A magnetic resonance study of normal and arthritic shoulders

INTRODUCTION

Axillary nerve injury is a major complication of shoulder surgery during glenoid exposure. The aim of this study was to measure the mean distance between the inferior glenoid and the axillary nerve in healthy shoulders and then to compare this distance between osteoarthritic and rotator cuff deficient glenohumeral joints.

METHODS

The magnetic resonance images of 50 patients with normal glenohumeral joints were reviewed. The infra-glenoid tubercle was determined as a fixed point and the distance to the axillary nerve was measured. Two separate assessors measured on the same sagittal sections. With a study power of 80%, the sample needed in each comparison group was 28 patients. Measurements were then performed on scans in patients with osteoarthritis and cuff tear arthropathy. The mean distance was compared between groups.

RESULTS

The mean distance between the infra-glenoid tubercle and axillary nerve was 12mm (standard deviation, SD, 5.6mm) in normal shoulders, 10.6mm (SD 5.4mm) in shoulders with osteoarthritis and 9.7mm (SD 3.7mm) in those with cuff tear arthropathy. For this sample size of 50 patients with a confidence interval of 95%, the mean range is 12mm (95% CI 10.4-13.6). A comparison between normal shoulder and osteoarthritis showed a p-value of 0.3, and between normal and cuff tear arthropathy a p-value of 0.06. This was not statistically significant.

CONCLUSIONS

The axillary nerve lies on average 12mm from the infra-glenoid tubercle. The presence of inferior osteophytes in glenohumeral osteoarthritis and the proximal migration of humeral head in cuff tear arthropathy does not seem to alter the course of the nerve significantly in relation to the inferior glenoid tubercle.

Morphometric analysis of the coracoid process and glenoid width: a 3D-CT study

Background

Data regarding the parameters of the coracoid process and glenoid width are insufficient, and information on gender, age, and ethnic differences in the parameters appear lacking in the Chinese population. This study aimed to investigate the morphometric parameters in the coracoid process and glenoid width.

Methods

Using our institution’s electronic database, we selected 84 patients (55 males and 29 females) who underwent a shoulder computed tomography (CT) scan from January 2017 to May 2018 in this study. Mimics19.0 software was used for three-dimensional (3D) reconstruction of CT and to measure the morphometric parameters of the coracoid process and glenoid width. Subgroup analyses stratified by gender and age were conducted and the parameters were compared with previously published reports. All data were statistically analysed by SPSS23.0 Statistical Package.

Results

A positive and significant relationship between the coracoid process and the glenoid width (R > 0.758, P < 0.01) was found. The midpoint width represents 52% (41–62%) of the glenoid width; the midpoint height, 40% (31–53%) of the glenoid width. Significant differences in all parameters between males and females were noted (P < 0.05). No significant differences among the age groups were observed (P > 0.05), whereas significant differences in almost all parameters between the ethnic groups were observed (P < 0.05).

Conclusion

Our results could supplement the information in the shoulder joint database with morphometric parameters and provide a reference for theoretical research on coracoid osteotomy, which may in turn help surgeons in the evaluation of coracoid process transfer.

Arthroscopic anatomy medial to the coracoid: an anatomic study of the axillary and musculocutaneous nerves

PURPOSE

The purpose of this study was to provide arthroscopic measurements and orientations of the axillary and musculocutaneous nerves medial to the coracoid.

METHODS

A retrospective chart review of 29 patients undergoing arthroscopic subscapularis repair and arthroscopic cadaveric dissection of 23 shoulders was used to analyze neuroanatomical distances to arthroscopic landmarks and to document the orientations of the axillary and musculocutaneous nerves using a clock face analogy. The clock face data was analyzed by separating the clock face into four quadrants and the frequency of any crossing nerve within each of the four quadrants was then determined.

RESULTS

In vivo, the axillary nerve was found 1.5 ± 0.5 cm medial to the coracoid tip and the musculocutaneous nerve was found 1.6 ± 0.6 cm medial to the coracoid tip. In cadavera, the axillary nerve was found 2.0 ± 0.6 cm medial to the coracoid tip and the musculocutaneous nerve was found 1.5 ± 0.5 cm medial to the coracoid tip. The posterosuperior quadrant of the subcoracoid space contained a crossing nerve in 4 of 29 (13.8%) patients undergoing arthroscopic rotator cuff repair medial to the coracoid, compared to 9 of 23 (39.1%) cadavera undergoing arthroscopic dissection medial to the coracoid. The posteroinferior quadrant contained a crossing nerve in 16 of 29 (55.2%) patients compared to 17 of 23 (73.9%) cadavera.

CONCLUSIONS

The axillary and musculocutaneous nerves run in close proximity to the coracoid tip and coracoid arch, most consistently within 1-2 cm medial to these structures, which is closer than has been previously documented in the literature. Crossing nerves are least frequently encountered within the posterosuperior quadrant of the subcoracoid space medial to the coracoid, followed by the posteroinferior quadrant. Arthroscopic dissection of this space should begin in the posterosuperior quadrant and carefully progress to the posteroinferior quadrant to decrease the risk of intraoperative nerve injury. Given the close proximity and frequently encountered nerves in this area, extreme caution must be exercised when working arthroscopically within the subcoracoid space.

The "coracoid tunnel view": a simulation study for finding the optimal screw trajectory in coracoid base fracture fixation

PURPOSE

Coracoid fractures represent approximately 3-13% of all scapular fractures. Open reduction and internal fixation can be indicated for a coracoid base fracture. This procedure is challenging due to the nature of visualization of the coracoid with fluoroscopy. The aim of this study was to develop a fluoroscopic imaging protocol, which helps surgeons in finding the optimal insertion point and screw orientation for fixations of coracoid base fractures, and to assess its feasibility in a simulation study.

METHODS

A novel imaging protocol was defined for screw fixation of coracoid base fractures under fluoroscopic guidance. The method is based on finding the optimal view for screw insertion perpendicular to the viewing plane. In a fluoroscopy simulation environment, eight orthopaedic surgeons were invited to place a screw down the coracoid stalk through the coracoid base and into the neck of 14 cadaveric scapulae using anatomical landmarks. The surgeons placed screws before and after they received an e-learning of the optimal view. Results of the two sessions were compared and inter-rater reliability was calculated.

RESULTS

Screw placement was correct in 33 out of 56 (58.9%) before, and increased to 50 out of 56 (89.3%) after the coracoid tunnel view was explained to the surgeons, which was a significant improvement (p < 0.001).

CONCLUSIONS

Our newly developed fluoroscopic view based on simple landmarks is a useful addendum in the orthopaedic surgeon's tool box to fixate fractures of the coracoid base.

Editorial Commentary: Is an Arthroscopic Single-Row Repair Effective for the Treatment of Chronically Retracted, Full-thickness Subscapularis Tears?

Retraction and scarring of subscapularis tears make arthroscopic fixation technically challenging. The ideal arthroscopic technique is still under debate, with new studies examining the importance of repairing the "leading edge." Regardless of single- or double-row fixation, it is our opinion that restoring the native anatomy as well as any concomitant biceps pathology is essential for postoperative success.

Editorial Commentary: Working Around the Coracoid-The Lighthouse to the Shoulder

Working around the coracoid has now become commonplace in arthroscopic shoulder surgery. No longer is there a safe side and a "suicide"; therefore, it is important to recognize the potential for neurovascular injury when surgery is performed about the coracoid. Although safe zones and distances are important, when more complex procedures are performed arthroscopically, direct visualization and identification of neurovascular structures is critical in avoiding iatrogenic injury.

Proximity of the Coracoid Process to the Neurovascular Structures in Various Patient and Shoulder Positions: A Cadaveric Study

PURPOSE

To examine and compare the distances from the anteromedial aspects of the coracoid base and the coracoid tip to the neurovascular structures in various patient positions.

METHODS

The experiment was conducted in 15 fresh-frozen cadavers. We dissected 15 right and 15 left shoulders to measure the distances from the anteromedial aspects of the coracoid base and the coracoid tip to the lateral border of the neurovascular structures in the horizontal, vertical, and closest planes. The measurements were performed with the cadavers in the supine, lateral decubitus, and beach-chair positions. With cadavers in the beach-chair position, we evaluated 5 arm postures (arm at side, 45° of abduction, 90° of abduction, 45° of forward flexion, and 90° of forward flexion).

RESULTS

The shortest distance from the coracoid base to the neurovascular structures was found in the beach-chair position with arm at side in the horizontal plane (27.4 ± 4.9 mm) and 90° of abduction in the vertical (21.8 ± 4.2 mm) and closest (19.5 ± 4.2 mm) planes. The distances in each plane were statistically significant compared with the supine and lateral decubitus positions (P < .005). Between the coracoid tip and the neurovascular structures, the shortest distance was found in the beach-chair position with 90° of abduction, with 29.3 ± 7.7 mm, 20.8 ± 4.9 mm, and 18.5 ± 5.1 mm in the horizontal, vertical, and closest planes, respectively. The distances were statistically significant in all planes compared with the supine and lateral decubitus positions (P < .005).

CONCLUSIONS

Shoulder surgery in the area of the coracoid process is safe, especially with the patient in the supine position. The distance from the coracoid process to the neurovascular structures was closest in the beach-chair position with 90° of arm abduction.

CLINICAL RELEVANCE

This study determined the distances between the coracoid process and the neurovascular structures during surgery around the coracoid process.

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.

Reliability of a CT reconstruction for preoperative surgical planning in the arthroscopic Latarjet procedure

PURPOSE

The arthroscopic Latarjet procedure has provided reliable results in the treatment of anterior shoulder instability. However, this procedure remains technically challenging and is related to several complications. The morphology of the coracoid and the glenoid are inconsistent. Inadequate coracoid and glenoid preparing may lead to mismatching between their surfaces. Inadequate screws lengthening and orientation are a major concern. Too long screws can lead to suprascapular nerve injuries or hardware irritation, whereas too short screws can lead to nonunions, fibrous unions or migration of the bone block. The purpose of the study was to investigate the application of virtual surgical planning and digital technology in preoperative assessment and planning of the Latarjet procedure.

METHODS

Twelve patients planned for an arthroscopic Latarjet had a CT scan evaluation with multi-two-dimensional reconstruction performed before surgery. Interobserver and intraobserver reliability were evaluated. The shape of the anterior rim of the glenoid and the undersurface of the coracoid were classified. Coracoid height was measured, respectively, at 5 mm (C1) and 10 mm (C2) from the tip of the coracoid process, corresponding to the drilling zone. Measurements of the glenoid width were then taken in the axial view at 25 % (G1) and 50 % (G2) of the glenoid height with various α angles (5°, 10°, 15°, 20°, 25°, 30°) 7 mm from the anterior glenoid rim. Shapes of the undersurface of the coracoid and the anterior rim of the glenoid were noted during the surgical procedure. Post-operative measurements included the α angle.

RESULTS

Concerning coracoid height measurements, there was an almost perfect to substantial intra- and inter-reliability, with values ranging from ICC = 0.75-0.97. For the shape of the coracoid, concordances were, respectively, perfect (ICC = 1) and almost perfect (0.87 [0.33; 1]) for the intra- and interobserver reliabilities. Concerning the glenoid, concordance was always almost perfect for 50 % height. Concordance was almost perfect for 25 % height 15° and 30° for inter- and intraobserver, for intraobserver at 0° and 25°. All the other values were still showing moderate concordance. Shape of the coracoid analysis reproducibility was perfect for both intra- and interobserver ICC = 1. There was a total agreement (ICC = 1) between the preoperative evaluation of the shape of the glenoid and the coracoid and the intraoperative assessment.

CONCLUSION

The ideal and accurate preoperative planning of screwing of the coracoid graft in the arthroscopic Latarjet can be achieved in the real surgery assisted by the virtual planning. The clinical importance of this study lies in the observation that this new preoperative planning could offer a simple, effective and reproducible tool for surgeons helping them to prepare in the best possible way a technically challenging procedure usually associated with a high rate of complications.

Effect of patient positioning in axillary nerve safety during arthroscopic inferior glenohumeral ligament plication

PURPOSE

To evaluate the risk of injuring the axillary nerve during an inferior glenohumeral ligament (IGHL) plication and finding out whether shoulder position (either beach chair position or lateral decubitus position) has any effect in this risk.

METHODS

The axillary nerve (AN) was identified through a 3-cm posterior incision in 12 cadaveric shoulders. Under arthroscopic visualization, a curved indirect suture-passing device was placed through the posterior and anterior bands of the IGHL. The distances between the device and the AN were measured with the shoulder specimen placed at simulated lateral decubitus position and beach chair position.

RESULTS

There were no cases of nerve injury nor the suture-passing device came closer than 10 mm to the nerve. There was an increase in the injury risk to the AN when inserting the device at the posterior band of the IGHL in the beach chair position [median 13 mm (range 10-21 mm)] compared to the risk in the lateral decubitus position [22.5 mm (20-26 mm), significant differences, p < 0.001]. When the device was inserted at the anterior band of the IGHL, there were no significant differences (n.s.) [lateral decubitus position: 18 mm (14-24 mm) vs. 16 mm (13-18 mm)]. When comparing differences between bands, there were no differences in the beach chair position, but the risk was lower for the posterior band in the lateral decubitus position (p < 0.001).

CONCLUSIONS

During plication of the posterior band of the IGHL, the risk is higher if the procedure is performed in the beach chair position. The posterior plication is safer than the anterior plication in lateral decubitus position.

CLINICAL RELEVANCE

This study helps the surgeon to better understand the proximity of the nerve to the IGHL and to highlight that the risk of nerve injury during capsular plication might be reduced in the lateral decubitus position.

Shoulder Arthroscopy in the Lateral Decubitus Position

Arthroscopic shoulder surgery can be performed in both the beach chair and lateral decubitus positions. The lateral decubitus position allows for excellent exposure to all aspects of the glenohumeral joint and is therefore frequently employed in procedures such as stabilization, in which extensive visualization of the inferior and posterior aspects of the joint is required. Improved visualization is imparted due to applied lateral and axial traction on the operative arm, which increases the glenohumeral joint space. To perform arthroscopy surgery in the lateral decubitus position successfully, meticulous care during patient positioning and setup must be taken. In this Technical Note, we describe the steps required to safely, efficiently, and reproducibly perform arthroscopic shoulder surgery in the lateral decubitus position.

Coracoid Process Morphology using 3D-CT Imaging in a Malaysian Population

Introduction: The aims of this study are to define the coracoid process anatomy in a Malaysian population, carried out on patients in Hospital Serdang with specific emphasis on the dimension of the base of coracoid process which is important in coraco-acromial (CC) ligament reconstruction, to define the average amount of bone available for use in coracoid transfer, and to compare the size of coracoid process based on gender and race, and with findings in previous studies.

Materials and Methods: Fifteen pairs of computed tomography (CT) based 3-dimensional models of shoulders of patients aged between 20 to 60 years old were examined. The mean dimensions of coracoid were measured and compared with regards to gender and race. The data were also compared to previously published studies.

Results: The mean length of the coracoid process was 37.94 ± 4.30 mm. Male subjects were found to have larger-sized coracoids in all dimensions as compared to female subjects. The mean tip of coracoid dimension overall was 19.99 + 1.93mm length × 10.03 + 1.48mm height × 11.63 + 2.12mm width. The mean base of coracoid dimension was 18.96 + 3.71mm length × 13.84 + 1.76mm width. No significant differences were observed with regards to racial denomination. The overall coracoid size measurements were found to be smaller compared to previous studies done on the Western population.

Conclusion: This study may suggest that Malaysians have smaller coracoid dimension compared to Caucasians. The findings further suggest that the incidence of coracoid fracture and implants pull out in Malaysian subjects may be higher.

Redefining anterior shoulder impingement: a literature review

Many different types of impingements have been described in the shoulder. Inasmuch as the term 'shoulder impingement' usually refers to subacromial impingement, anterior impingement usually refers to subcoracoid impingement. However, there are many different subtypes of anterior impingements in the shoulder, and awareness of their existence is critical as they vary in their nature and treatment. Recent advances in biomechanical research and arthroscopic exploration of the anterior structures of the shoulder have brought new insights on the various potential impingements, warranting a revision and update of the current definitions of anterior shoulder impingement. The purpose of this article is to propose a comprehensive review and classification of all different subtypes of anterior impingement in the shoulder, including newly described entities.

Effectiveness of a Low-Cost Drilling Module in Orthopaedic Surgical Simulation

INTRODUCTION

Financial pressures and resident work hour regulations have led to adjunct means of resident education such as surgical simulation. The purpose of this study is to determine the effectiveness of a hands-on training session in orthopaedic drilling technique educational model during a surgical simulation on reducing drill plunging depth and to determine the effectiveness of senior residents teaching a hands-on training session in orthopaedic drilling technique.

METHODS

A total of 13 participants (5 orthopaedic interns and 8 medical students) drilled until they penetrated the far cortex of a synthetic bone model and the plunging depth (PD) was measured. They were then randomized and underwent an education session with an attending orthopaedic surgeon or a senior resident. Next, the subjects drilled again with the PD being calculated. The preeducational and posteducational session were compared to determine if there was any improvement in PD and if there was a difference between educators. The cost of the model was also determined.

RESULTS

The mean maximum PD and mean PD before the education session was 1.58 (1.40-2.10) and 1.50cm (1.36-1.76), respectively. Following the educational session, the mean maximum PD and mean PD were 0.53 (0.42-0.75) and 0.50cm (0.40-0.72), respectively. These were both significantly lower than before the education session (p <0.05). After the educational session taught by the attending versus the session taught by the resident, the mean maximum PD was 0.59 (0.42-0.75) and 0.49cm. (0.45-0.75), respectively (p = 0.44). After the educational session taught by the attending versus the session taught by the resident, the mean PD was 0.54 (0.40-0.72) and 0.47cm. (0.40-0.65), respectively (p = 0.44). The cost of the station per participant was $5.44.

CONCLUSION

This study demonstrated a significant reduction in drilling PD with use of a low-cost training model and a formal didactic and skills session on proper drilling technique that can effectively be led by senior residents.

Anatomic Variation in Morphometry of Human Coracoid Process among Asian Population

Ethnic origin plays an important role in bone morphometry. Studies examining the influence of coracoid process have focused primarily on adults and have not included people from diverse Asian ethnic backgrounds. Our goal was to explore ethnic differences in morphometry of coracoid among Asian population. We performed morphometric measurements of coracoid process on cadaveric shoulders and shoulder CT scans from 118 specimens. The cadaveric sample included Indian (46%), Chinese (27%), and Myanmarese (27%) subjects, while the CT scans sample included Chinese (67%) and Malay (33%) subjects. The morphometric measurements were performed using digital caliper and software developed at Golden Horses Health Sanctuary (GHHS). In the Indian cadaveric shoulders, the coracoid process is better developed than the other groups with the exception of the tip width of coracoid process. There are significant differences in almost all measurements (P < 0.05) between the ethnic groups. On the other hand, the morphometry of coracoid process from CT scans data is bigger in Chinese than Malay subjects when stratified by sex (P < 0.05). Moreover, in all morphometric measurements, the females had smaller measurements than males (P < 0.05). Understanding such differences is important in anatomy, forensic and biological identity, and orthopaedic and shoulder surgeries.

Arthroscopic Reconstruction of the Coracoclavicular Ligaments Using a Coracoid Cerclage Technique

This technical note discusses the arthroscopic coracoid cerclage technique for double-bundle coracoclavicular ligament reconstruction in patients with nonacute symptomatic high-grade acromioclavicular separation injuries. This technique allows for an anatomic graft reconstruction of the coracoclavicular ligaments through an arthroscopic approach without the requirement to drill into the coracoid process. Early results are promising with high patient satisfaction and excellent reported clinical and radiographic outcomes. We believe this technique to be an anatomic, less invasive alternative to a complex shoulder procedure while sparing the structural integrity of the coracoid process and also allowing the surgeon to convert easily to a more traditional open surgical technique as necessary.

[New arthroscopic portal for performing tenotomy/tenodesis procedures on the long head of the biceps brachii tendon]

BACKGROUND

Shoulder arthroscopy is the standard technique for performing procedures involving the intertubercular groove. Current techniques continue to produce excessive soft tissue manipulation and neurovascular injury.

MATERIALS AND METHODS

A cross-sectional, observational and descriptive study was conducted on a cohort of 24 shoulders following the standard surgical protocol and using punch dissection. The neurovascular structures with risk of damage by the standard lateral portal were evaluated during the study to establish a secure area for a new arthroscopic portal. Finally, the safety of the new proposed site was evaluated.

RESULTS

The presence of 24 venous structures, with a mean diameter was 1.05mm (SD: 0.71) was documented. A tendency was observed in locating these structures in the lower half of the dissecting field for the left shoulders and a hypovascular area between the 7 and 10hours circle dissected relative to the right shoulder. The new site was determined at a point 1.5 cm anterolateral to the anterolateral border of the acromion at an angle of 60° degrees to the horizontal axis of the acromion and towards the intertubercular groove of the humerus.

CONCLUSIONS

The methodology used in this study is innovative, reproducible and applicable for the study of all existing shoulder arthroscopic portals procedures, as well as any joint. The results provided by this study will be helpful for clinicians to improve tenotomy/tendon tenodesis procedures of the long head of the biceps brachii tendon.

Axillary nerve course and position in the fetal period. An anatomic dissection study for surgical practice

OBJECTIVE

To examine the fetal axillary nerve to reveal and compare its morphometric features within the second and third trimester.

METHODS

This study was conducted at the Anatomy Department, School of Medicine, Mersin University, Mersin, Turkey. Thirty-five fetal shoulders were studied to provide anatomic data and to describe its position with regard to certain landmarks around the shoulder.

RESULTS

The shortest distance between the axillary nerve and the glenoid labrum was found 2.27 mm and 2.89 mm in the second and third trimester fetuses, respectively. The shortest distances between the anterior and posterior acromial tips and the axillary nerve were also measured and were used with arm length measurements to define the anterior and posterior indexes.

CONCLUSION

The indexes show that the distance between the axillary nerve and the anterior/posterior acromial tips are approximately one-fourth of the arm length in both the second and third trimester fetuses. The data presented in this study will be of use to surgeons, particularly to pediatric and orthopedic surgeons who will undertake surgical procedures in the axilla and arm in the newborn or early childhood.

Outcome After Arthroscopic Reconstruction of the Coracoclavicular Ligaments Using a Double-Bundle Coracoid Cerclage Technique

PURPOSE

We report the outcome of an arthroscopic technique for coracoclavicular ligament reconstruction using an anatomic coracoid cerclage.

METHODS

Between March 2011 and September 2012, 12 consecutive patients with symptomatic chronic (>4 weeks from injury) type V acromioclavicular separation for which nonoperative treatment failed were treated with arthroscopic double-bundle reconstruction of the coracoclavicular ligaments using tendon allograft by the first author. The clinical records, operative reports, and preoperative and follow-up radiographs were reviewed. The visual analog scale score, Subjective Shoulder Value, Simple Shoulder Test score, and Constant-Murley score were evaluated preoperatively and at each follow-up appointment.

RESULTS

The study included 12 shoulders in 12 young active-duty soldiers with symptomatic high-grade acromioclavicular separation who were treated with a technique for arthroscopic reconstruction of the coracoclavicular ligaments. The mean age was 25 years (range, 20 to 35 years). The injury occurred during sports activity in 11 patients. One patient was injured in a motorcycle accident. The mean time from injury to surgery was 17.8 months (range, 1.5 to 72 months). The minimum length of follow-up was 24 months (mean, 30.4 months; range, 24 to 42 months). The mean preoperative and postoperative outcome scores were significantly different (P < .0001) for all subjective outcome measures. The mean Constant-Murley score improved from 58.4 (range, 51 to 76) to 96 (range, 88 to 100). The mean visual analog scale score improved from 8.1 (range, 7 to 10) to 0.58 (range, 0 to 2). The mean Subjective Shoulder Value improved from 32.9% (range, 10% to 70%) to 95% (range, 80% to 100%). The mean Simple Shoulder Test score improved from 6 (range, 5 to 8) to 11.83 (range, 11 to 12). All patients returned to their normal preinjury level of activity by 6 months. Radiographs at last follow-up showed no loss of reduction with maintenance of the coracoclavicular interval. There was 1 complication (8.5%), a postoperative superficial wound infection, that was treated accordingly.

CONCLUSIONS

We present an arthroscopic technique for double-bundle tendon graft reconstruction of the coracoclavicular ligaments using the coracoid cerclage technique. This method showed good outcomes and maintenance of radiographic reduction with high patient satisfaction and a low complication rate.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Complications of shoulder arthroscopy

Over the past 20 to 30 years, arthroscopic shoulder techniques have become increasingly popular. Although these techniques have several advantages over open surgery, surgical complications are no less prevalent or devastating than those associated with open techniques. Some of the complications associated with arthroscopic shoulder surgery include recurrent instability, soft-tissue injury, and neurapraxia. These complications can be minimized with thoughtful consideration of the surgical indications, careful patient selection and positioning, and a thorough knowledge of the shoulder anatomy. Deep infection following arthroscopic shoulder surgery is rare; however, the shoulder is particularly susceptible to Propionibacterium acnes infection, which is mildly virulent and has a benign presentation. The surgeon must maintain a high index of suspicion for this infection. Thromboemoblic complications associated with arthroscopic shoulder techniques are also rare, and studies have shown that pharmacologic prophylaxis has minimal efficacy in preventing these complications. Because high-quality studies on the subject are lacking, minimal evidence is available to suggest strategies for prevention.

Relationship of the subscapular nerves to the base of the coracoid

PURPOSE

This study was performed to determine the relation of the subscapular nerves to the medial base of the coracoid when using an arthroscopic approach.

METHODS

Twenty human cadaveric shoulder specimens were dissected, and measurements were taken from the medial base of the coracoid to the innervation points of the upper and lower subscapular nerves. Measurements were obtained with the humerus in both neutral and maximal external rotation.

RESULTS

The average distance of the upper subscapular nerve from the coracoid base was 31.6 ± 6.6 mm (range, 22 to 45 mm) in neutral rotation and 24.2 ± 7.4 mm (range, 11 to 35 mm) in external rotation. The lower subscapular nerve's insertion point averaged 42.6 ± 7.6 mm (range, 25 to 55 mm) from the coracoid base in neutral rotation and 33.9 ± 6.9 mm (range, 24 to 45 mm) in external rotation. For both nerves, their distance from the coracoid significantly decreased when the humerus was placed in external rotation.

CONCLUSIONS

The closest that the innervation point of either the upper or lower subscapular nerve came to the medial aspect of the coracoid was 11 mm.

CLINICAL RELEVANCE

Understanding the relationship of the subscapular nerves to the base of the coracoid allows a safe arthroscopic release of a retracted subscapularis muscle that has formed adhesions to the inferior aspect of the coracoid. Use of an arthroscopic elevator to release adhesions between the subscapularis and the inferior aspect of the coracoid does not appear to risk denervation of the subscapularis muscle.

Coracoid impingement: current concepts

For many years, coracoid impingement has been a well-recognized cause of anterior shoulder pain. However, a precise diagnosis of coracoid impingement remains difficult in some cases due to the presence of multifactorial pathologies and a paucity of supporting evidence in the literature. This review provides an update on the current anatomical and biomechanical knowledge regarding this pathology, describes the diagnostic process, and discusses the possible treatment options, based on a systematic review of the literature. Level of evidence V.

Plunging when drilling: effect of using blunt drill bits

OBJECTIVE

Plunging when drilling can be a detrimental factor in patient care. There is, although, a general lack of information regarding the surgeon's performance in this skill. The aim of this study was to determine the effect that using sharp or blunt instruments had on the drill bit's soft tissue penetration, using a simulator.

MATERIALS AND METHODS

Surgeons taking part in an International Trauma Course were invited to participate. Two groups were defined: experienced and inexperienced surgeons. Twelve holes were drilled in the following order: 3 holes with a sharp drill bit in normal bone (SNB), 3 holes with a sharp drill bit in osteoporotic bone (SOB), 3 holes with a blunt drill bit in normal bone, and 3 holes with a blunt drill bit in osteoporotic bone. Mean values and Student t tests were used for statistical analysis.

RESULTS

Thirty-seven surgeons participated, 20 experienced and 17 inexperienced surgeons. Mean plunging depths for SNB, SOB, blunt drill bit in normal bone, and blunt drill bit in osteoporotic bone were, respectively, 5.1, 5.4, 21.1, and 13.9 mm for experienced surgeons and 7.6, 7.7, 22, and 15.9 mm for inexperienced surgeons. Drilling with SNB and with SOB was statistically different, with inexperienced surgeons plunging 2.5 mm (P = 0.31) and 2.6 mm (P = 0.042) deeper, respectively. There was a difference (P < 0.001) between sharp and blunt drill bits in all drilling conditions for both the groups.

CONCLUSIONS

Our study showed a significant difference in plunging depth when sharp or bunt drill bit was being used. Surgeons, regardless of their experience level, penetrate over 20 mm in normal bone and over 10 mm in osteoporotic bone.

Orthogonal biplanar fluoroscopy-guided percutaneous fixation of a coracoid base fracture associated with acromioclavicular joint dislocation

Coracoid process fractures that involve the coracoid base (inferior pillar) without a concomitant rupture of the coracoclavicular ligaments can destabilize the acromioclavicular joint with its subsequent dislocation; prophylactic or therapeutic operative treatment involving open reduction and internal fixation has been traditionally recommended. This report presents a new technique of percutaneous reduction and stabilization of the coracoid fracture with indirect acromioclavicular joint reduction under fluoroscopic guidance; biplanar visualization of coracoid process anatomy is obtained using 2 specific radiographic/fluoroscopic-beam angulations (Bhatia views), and this permits a guided placement of screws for controlled reduction of this dual injury. The technique is based on the author's original work on coracoid process anatomy and development of radiographic views for orthogonal visualization of coracoid pillars in their entirety. Technical tips to facilitate percutaneous fracture fixation and to avoid potential complications are discussed.

Prediction of coracoid thickness using a glenoid width-based model: implications for bone reconstruction procedures in chronic anterior shoulder instability

BACKGROUND

Chronic anterior shoulder instability with glenoid bone loss can be a very challenging clinical problem. Significant bone loss is commonly managed with the Latarjet procedure. However, in some cases with severe glenoid bone loss, iliac crest bone grafting is required to obtain a graft of adequate size. Iliac crest bone graft is associated with high rates of donor-site complications. Whereas glenoid dimensions can be determined by use of 3-dimensional computed tomography reconstructions, the thickness of the coracoid cannot be easily measured. This study aims to define a ratio between glenoid width and coracoid thickness that can be used in preoperative planning to determine whether coracoid transfer will yield adequate bone graft to restore glenoid contour or whether iliac crest bone graft must be taken.

METHODS

We studied 100 paired cadaveric scapulae (50 male and 50 female scapulae). The bony dimensions of the coracoid and glenoid were measured for each specimen.

RESULTS

Coracoid and glenoid dimensions are provided. The mean thickness of the male coracoid was 35.4% of the width of the glenoid. The mean female coracoid thickness was 34.4% of the glenoid width.

DISCUSSION

A new biomorphologic model is presented to predict coracoid thickness and the ability of the Latarjet procedure to restore stability to a given bone-deficient glenoid. This model may aid the shoulder surgeon in preoperative planning and help promote successful outcomes in glenoid reconstruction surgery by determining whether a Latarjet procedure or iliac crest bone graft is the most appropriate procedure given the predicted amount of coracoid bone graft available.

Arthroscopic management of subscapularis tears

Tears of the subscapularis were previously believed to be rare, but are now recognized to be very common. As maintenance of the subscapularis footprint is integral to normal biomechanical function of the shoulder it is important for the shoulder surgeon to be adept at recognizing and treating these tears. A combination of physical examination tests can be used to determine both the presence and size of a subscapularis tear. Compared with posterosuperior rotator cuff tears, magnetic resonance imaging detection of subscapularis is less reliable and therefore requires a high index of suspicion. Arthroscopic repair of the subscapularis presents unique challenges but can be safely and successfully performed with careful attention to detail. The results of arthroscopic subscapularis repair are encouraging at intermediate follow-up and comparable with or better than that reported with open repair.

Evaluation of arthroscopic stabilization of acute acromioclavicular joint dislocation using the TightRope system

The purpose of this study was to evaluate the results of the arthroscopic treatment of acute acromioclavicular dislocation using the TightRope system (Arthrex, Naples, Florida). Between January 2006 and May 2007, ten shoulders in 10 patients with acute acromioclavicular joint dislocation (Rockwood types IV and V) underwent arthroscopic acromioclavicular joint stabilization using the TightRope. Average patient age was 30 years (range, 22-42 years), and mean follow-up was 24 months (range, 18-30 months). Follow-up occurred at 2 and 6 weeks, 3 months, and then every 6 months postoperatively. The shoulders were evaluated radiologically by comparing the acromioclavicular joint with the normal side and clinically by assessing the pain, function, and range of joint motion using the Constant score.Ten patients returned to work without pain 10 to 12 weeks postoperatively. Average Constant score was 96.3 (range, 94-99) at last follow-up. Because of technical error, 1 patient experienced TightRope fixation failure on the coracoid side, and the acromioclavicular joint was redislocated, which was treated by an open technique. The 10 patients were satisfied with their functional results and cosmetic appearance.The arthroscopic treatment of acute acromioclavicular dislocation using the TightRope is a minimally invasive surgical technique that has been proven effective for the treatment of these lesions. It is characterized by less morbidity, less hospitalization, excellent cosmoses, and early rehabilitation.