Acromioclavicular Joint Capsule Research Articles

Tunnel-free acromioclavicular joint reconstruction is associated with improved initial reduction and higher patient satisfaction

Many surgical techniques have been described for acromioclavicular (AC) joint reconstruction. Creation of bone tunnels through the clavicle or coracoid has been shown to be a risk factor for fracture. Use of an AC reconstruction technique that does not create bone tunnels may obviate this risk. This study aims to evaluate clinical outcomes of AC joint reconstruction using a tunnel-free technique compared to reconstruction using a cortical button and clavicular drill holes. Consecutive patients who underwent AC joint reconstruction by a single surgeon in a subspecialty referral practice were included. One group of patients received cortical button fixation (button group), in which sutures were passed around the coracoid, brought up through a drill hole in the clavicle, and tied over a cortical button. The other group of patients received tunnel-free fixation, in which a self-locking tape suture was passed in a cerclage fashion around the base of the coracoid and the clavicle and tensioned with a tensioning device (cerclage group). Both groups underwent reconstruction of the coracoclavicular (CC) ligament and AC joint capsule using tibialis anterior allograft. Patient-reported outcome scores and satisfaction were collected and compared between groups. Radiographs were reviewed to evaluate CC ligament distance and loss of reduction. Twenty-two patients were included in the study (button n= 10, cerclage n= 12). Preoperative demographics and injury characteristics were not different between groups. Average radiographic follow-up was not different between groups (button: 231 days, cerclage: 105 days). Postoperative American Shoulder and Elbow Surgeons, visual analog scale, and Single Assessment Numeric Evaluation scores were similar between groups. Two postoperative clavicle fractures were sustained in the button group. These occurred through clavicular drill holes and were preceded by tunnel widening. No fractures occurred in the cerclage group. CC distance at initial follow-up was significantly less in the cerclage group (button: 11.2 ± 4.5 mm, cerclage: 7.0 ± 2.9 mm, P=.023). Loss of reduction was similar throughout the postoperative period (button: 4.3 ± 2.6 mm, cerclage: 4.8 ± 4.1 mm, P >.05. Forty percent of patients were unsatisfied with their clavicle after button fixation (n= 4/10), compared with zero after cerclage fixation (n= 0/12, P=.03). Reasons for dissatisfaction were fracture (n= 2) and persistent cosmetic deformity (n= 2). Tunnel-free AC joint reconstruction is associated with improved initial radiographic appearance and patient satisfaction compared to single cortical button fixation. Postoperative clavicle fracture and persistent cosmetic deformity drive patient dissatisfaction, which may be minimized by avoiding clavicular drill holes and using a tensioned self-locking cerclage suture to improve initial reduction.

Arthroscopic-Assisted Coracoclavicular and Acromioclavicular Ligament Reconstruction for Chronic AC Joint Separation

Background: Management of acromioclavicular joint (ACJ) separations depends on the type, chronicity of injury, and patient demographics. Indications: Coracoclavicular and acromioclavicular ligament reconstruction may be indicated for patients with chronic type 3 ACJ separation who have failed conservative treatment. We describe an arthroscopic-assisted approach to facilitate graft passage around the coracoid. Technique: Patients are placed in a beach chair position. A longitudinal incision at the midline of the distal clavicle is utilized for access to the ACJ, the distal clavicle, and the coracoid. The anterior, posterior, and undersurface of the distal clavicle are exposed. A standard posterior viewing and anterolateral working portals are created. A shuttling suture is passed arthroscopically and used to pass allograft and nonbiologic augmentation around the coracoid. The nonbiologic sutures are passed through a singular hole in the distal clavicle and secured with a DogBone button. The allograft is wrapped around the clavicle to recreate the coracoclavicular ligaments and secured with sutures. The ACJ capsule is reconstructed by suturing the posterior/medial limb, which is kept long, to the capsule and periosteum. Meticulous, layered closure is performed with particular attention to closing the deltotrapezial fascia. Results: A postoperative x-ray at 2 weeks and 6 months are obtained to confirm proper positioning. The sling is discontinued at 6 weeks, and supervised physical therapy is initiated. At 6 months, patients are typically cleared to full unrestricted activity. Discussion/Conclusion: Arthroscopic-assisted coracoclavicular and acromioclavicular ligament reconstruction in patients with chronic type 3 ACJ separation who fail conservative management can have excellent outcomes. The use of arthroscopic assistance may ease the passage of graft and nonbiologic suture around the coracoid. A 70° scope is helpful for coracoid visualization, and biologic reconstruction of the ligament with tendon graft with suture augmentation in chronic cases is vital in achieving a good outcome. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Subject-specific computational modeling of acromioclavicular and coracoclavicular ligaments.

Disruption of the acromioclavicular joint is a common injury. Despite the different surgical procedures described for treating this injury, complications such as loss of reduction and failure of fixation remain unacceptably high. We developed a computer model of the acromioclavicular joint to better understand the biomechanical contributions of the ligaments that are typically injured. Six fresh frozen human cadaveric shoulders were tested on an AMTI VIVO 6-degree of freedom test platform to measure force-displacement in inferior translation, anteroposterior translation, and internal rotation before and after sequentially transecting the coracoclavicular and acromioclavicular ligaments. These data were used to construct computer models of each specimen. Three-dimensional computed tomographic scans were used to generate a rigid-body dynamics model using the AnyBody Modeling System. The scapula and clavicle were connected by the acromioclavicular joint capsule, the conoid ligament, and the trapezoid ligament. Subject-specific ligament properties were calculated by matching computer predictions to experimental force-displacement data. The calculated free lengths of the conoid, trapezoid, and acromioclavicular ligaments were 13.5 (±3.2), 11.8 (±2.4), and 11.0 (±2.7) mm, respectively. The calculated stiffnesses of the conoid, trapezoid, and acromioclavicular ligaments were 34.3 (±6.3), 28.4(±3.2), and 33.8 (±8.2) N/mm, respectively. Root mean square deviation (RMSD) of predicted force-displacement curves relative to experimental force-displacement curves (during inferior and anteroposterior translation) was less than 1 mm. For validation of subject-specific models, after ligament properties were calculated, the RMSD of the predicted torque over 15° of internal rotation was 12% of maximum rotational torque (average for 6 specimens). Acromioclavicular disruption results in multidirectional instability, which requires careful consideration of the individual contributions of the injured ligaments. In addition, variations in patient anatomy can significantly affect the biomechanical stability of the reconstruction. Subject-specific models can enhance our understanding of the individual and collective biomechanical contributions of the injured soft tissues to the multiaxial stability of the acromioclavicular joint. These models may also be useful for analyzing and assessing biomechanical stability after various types of surgical reconstruction.

Deltotrapezial Stabilization of Acromioclavicular Joint Rotational Stability: A Biomechanical Evaluation.

Despite advances in surgical management of acromioclavicular (AC) joint reconstruction, many patients fail to maintain sustained anatomic reduction postoperatively. To determine the biomechanical support of the deltoid and trapezius on AC joint stability, focusing on the rotational stability provided by the muscles to posterior and anterior clavicular rotation. A novel technique was attempted to repair the deltoid and trapezius anatomically. Controlled laboratory study. Twelve human cadaveric shoulders (mean ± SD age, 60.25 ± 10.25 years) underwent servohydraulic testing. Shoulders were randomly assigned to undergo serial defects to either the deltoid or trapezius surrounding the AC joint capsule, followed by a combined deltotrapezial muscle defect. Deltotrapezial defects were repaired with an all-suture anchor using an anatomic technique. The torque (N·m) required to rotate the clavicle 20° anterior and 20° posterior was recorded for the following conditions: intact (native), deltoid defect, trapezius defect, combined deltotrapezial defect, and repair. When compared with the native condition, the deltoid defect decreased the torque required to rotate the clavicle 20° posteriorly by 7.1% (P = .206) and 20° anteriorly by 6.1% (P = .002); the trapezial defect decreased the amount of rotational torque posteriorly by 5.3% (P = .079) and anteriorly by 4.9% (P = .032); and the combined deltotrapezial defect decreased the amount of rotational torque posteriorly by 9.9% (P = .002) and anteriorly by 9.4% (P < .001). Anatomic deltotrapezial repair increased posterior rotational torque by 5.3% posteriorly as compared with the combined deltotrapezial defect (P = .001) but failed to increase anterior rotational torque (P > .999). The rotational torque of the repair was significantly lower than the native joint in the posterior (P = .017) and anterior (P < .001) directions. This study demonstrated that the deltoid and trapezius play a role in clavicular rotational stabilization. The proposed anatomic repair improved posterior rotational stability but did not improve anterior rotational stability as compared with the combined deltotrapezial defect; however, neither was restored to native stability. Traumatic or iatrogenic damage to the deltotrapezial fascia and the inability to restore anatomic deltotrapezial attachments to the acromioclavicular joint may contribute to rotational instability. Limiting damage and improving the repair of these muscles should be a consideration during AC reconstruction.

Acromioclavicular joint instability on cross-body adduction view: the biomechanical effect of acromioclavicular and coracoclavicular ligaments sectioning

BackgroundThe acromioclavicular (AC) and coracoclavicular (CC) ligaments are important stabilizers of the AC joint. We hypothesized that AC and trapezoid ligament injuries induce AC joint instability and that the clavicle can override the acromion on cross-body adduction view even in the absence of conoid ligament injury. Accordingly, we investigated how sectioning the AC and CC ligaments contribute to AC joint instability in the cross-body adduction position.MethodsSix fresh-frozen cadaveric shoulders were used in this study, comprising five male and one female specimen, with a mean age of 68.7 (range, 51–87) years. The left side of the trunk and upper limb, and the cervical and thoracic vertebrae and sternum were firmly fixed with an external fixator. The displacement of the distal end of the clavicle relative to the acromion was measured using an electromagnetic tracking device. We simulated AC joint dislocation by the sequential resection of the AC ligament, AC joint capsule, and CC ligaments in the following order of stages. Stage 0: Intact AC and CC ligaments and acromioclavicular joint capsule; stage 1: Completely sectioned AC ligament, capsule and joint disc; stage 2: Sectioned trapezoid ligament; and stage 3: Sectioned conoid ligament. The superior clavicle displacement related to the acromion was measured in the horizontal adduction position, and clavicle overriding on the acromion was assessed radiologically at each stage. Data were analyzed using a one-way analysis of variance and post-hoc tests.ResultsSuperior displacement was 0.3 mm at stage 1, 6.5 mm at stage 2, and 10.7 mm at stage 3. On the cross-body adduction view, there was no distal clavicle overriding at stages 0 and 1, and distal clavicle overriding was observed in five cases (5/6: 83%) at stage 2 and in six cases (6/6: 100%) at stage 3.ConclusionWe found that AC and trapezoid ligament sectioning induced AC joint instability and that the clavicle could override the acromion on cross-body adduction view regardless of conoid ligament sectioning. The traumatic sections of the AC and trapezoid ligament may lead to high grade AC joint instability, and the distal clavicle may subsequently override the acromion.

Shoulder impingement syndrome in water polo players: muscle shortening manoeuvre controls pain intensity, recovers function and normalizes sonographic parameters.

To evaluate the effects of muscle shortening manoeuvre (MSM) by sonography (US) in professional water polo players with shoulder impingement syndrome (SIS). Twenty-four professional water polo players (mean age: 22.13 ± 3.34) with SIS were assigned to one of 2 different treatment interventions: Group (1) MSM: a series of fast accelerationsin the upward direction was applied to the upper limb that's connected to a spring through a metal plate with a ring. The ring was linked to a pulley system that was submitted to forces acting in the opposite direction (added mass). Group (2) Simple traction: the series of fast accelerations were performed without the springs. Pain intensity, Yocum and Hawkins tests for SIS, Neer's impingement sign, range of motion, muscle strength and shoulder US were assessed. The examination was performed before, immediately after and 30days after each treatment to study the US width of subacromial-subdeltoid bursa (SSB), thickness of supraspinatus (ST), long biceps tendons (LBT); hypoechoic halo of surrounding the long biceps (LBH) and subscapular tendons (STH); width of acromio-clavicular joint capsule (ACJ) and the distance between bone heads (ACD). Impingement sign (IS) was evaluated by dynamic examination. Immediately after treatment with MSM, pain was much reduced (p = 0.002); Yocum and Hawkins tests were decreased (p = 0.008, p = 0.031); Neer's impingement sign was negative; range of motion and muscle strength were increased. US showed that the following parameters were significantly reduced: SSB (p = 0.001), LBT (p = 0.014), LBH (p = 0.014), SSH (p = 0.002), ACJ (p = 0.004), ACD (p = 0.001). IS was no more detected. After 30days, the improvement of clinical and US findings was maintained. In the control group, after simple traction, no clinical amelioration of US parameters was found immediately after the procedure. These data show that MSM could be significantly and rapidly effective against pain and the loss of function due to shoulder impingement in water polo players.

Acromioclavicular joint reconstruction implants have differing ability to restore horizontal and vertical plane stability

PurposePersistent acromioclavicular joint (ACJ) instability following high grade injuries causes significant symptoms. The importance of horizontal plane stability is increasingly recognised. There is little evidence of the ability of current implant methods to restore native ACJ stability in the vertical and horizontal planes. The purpose of this work was to measure the ability of three implant reconstructions to restore native ACJ stability.MethodsThree groups of nine fresh-frozen shoulders each were mounted into a robotic testing system. The scapula was stationary and the robot displaced the clavicle to measure native anterior, posterior, superior and inferior (A, P, S, I) stability at 50 N force. The ACJ capsule, conoid and trapezoid ligaments were transected and the ACJ was reconstructed using one of three commercially available systems. Two systems (tape loop + screw and tape loop + button) wrapped a tape around the clavicle and coracoid, the third system (sutures + buttons) passed directly through tunnels in the clavicle and coracoid. The stabilities were remeasured. The data for A, P, S, I stability and ranges of A–P and S–I stability were analyzed by ANOVA and repeated-measures Student t tests with Bonferroni correction, to contrast each reconstruction stability versus the native ACJ data for that set of nine specimens, and examined contrasts among the reconstructions.ResultsAll three reconstructions restored the range of A–P stability to that of the native ACJ. However, the coracoid loop devices shifted the clavicle anteriorly. For S–I stability, only the sutures + buttons reconstruction did not differ significantly from native ligament restraint.ConclusionsOnly the sutures + buttons reconstruction, that passed directly through tunnels in the clavicle and coracoid, restored all stability measures (A, P, S, I) to the native values, while the tape implants wrapped around the bones anteriorised the clavicle. These findings show differing abilities among reconstructions to restore native stability in horizontal and vertical planes. (300 words)

Three-Dimensional Footprint Mapping of the Deltoid and Trapezius: Anatomic Pearls for Acromioclavicular Joint Reconstruction

To perform a quantitative anatomic evaluation of the deltoid and trapezius footprints in relation to the lateral clavicle and acromioclavicular (AC) joint capsule to assist in surgical technique of AC joint reconstructions. Fourteen fresh-frozen human cadaveric shoulders from 9 donors were analyzed. Meticulous dissection of the deltoid origin and trapezius insertions to the clavicle and AC joint was performed. Footprints were reconstructed using a MicroScribe digitizer. The inferior extension of the deltoid origin beneath the lateral clavicle and the footprints of the deltoid and trapezius onto the acromioclavicular ligamentous complex (ACLC) were quantified. Reproducibility was assessed by redigitizing 5 shoulders in a blinded and random fashion. The anterior deltoid fibers extended on average 4.0 ± 1.6 mm inferiorly with respect to the anteroinferior clavicular ridge and attached to 90.9 ± 7.3% of the anterior ACLC. The trapezius inserted onto the posterior and superior ACLC, covering 15.3 ± 3.4% of the anterior-posterior width of the superior capsule. The deltopectoral interval was 6 cm, or 37% the length of the clavicle from the distal end of the clavicle. The deltoid has superior, anterior, and not as well described, inferior attachments to the lateral clavicle. Furthermore, the deltoid and trapezius muscles have intimate attachments to the AC joint capsule, particularly the trapezius to the posterior and posterosuperior capsule. Lastly, the deltoid origin attaches to the lateral 6 cm of the clavicle. Subperiosteal elevation of the deltoid off the lateral clavicle starting superiorly, anteriorly, and lastly inferiorly will reduce deltoid muscle injury and improve visibility of the coracoid process during reconstruction. Furthermore, knowledge of the attachments of the deltoid and trapezius to the ACLC may help limit iatrogenic injury to these dynamic stabilizers.

The reverse coracoacromial ligament transfer for “horizontal” acromioclavicular joint instability

Acromioclavicular (AC) horizontal instability is a problem affecting not only young athletic patients after a trauma to the AC joint but also older patients who have undergone distal clavicle resection. It may cause pain and poor functional outcomes unless the reconstruction technique specifically addresses the horizontal instability of the clavicle, in addition to the well-known superior instability. Three cadaveric specimens underwent dissection of the AC joint capsule to determine the superior attachments of the AC joint capsule. These shoulders subsequently underwent distal clavicle resection and were loaded to a 7-kg weight in the horizontal plane. The horizontal displacement of the clavicle was measured and resection continued to the point of horizontal instability of the clavicle. Thereafter, the reverse coracoacromial ligament reconstruction technique was performed and recreation of horizontal stability assessed. Utilization of the reverse coracoacromial ligament transfer in two clinical cases will also be presented. The AC joint capsule is continuous with trapezius and deltoid insertions. The average distance between the articular surface and insertion of the capsule on the clavicle is 10 mm and on the acromion is 14.8 mm. Horizontal clavicular translation increased from 2.3 mm when intact to 3.3 mm with capsular transection, 8.7 mm with 5 mm clavicle resection, and finally 15 mm with a 10-mm clavicle resection. Horizontal instability of the clavicle was demonstrated with a 10-mm clavicle resection. Horizontal instability of the clavicle is evident with distal clavicle resection of greater than 10 mm. A reverse coracoacromial ligament transfer may be a reasonable technique to address horizontal stability of the clavicle during AC joint reconstruction in the context of painful instability.

Quantitative and Qualitative Surgical Anatomy of the Acromioclavicular Joint Capsule and Ligament: A Cadaveric Study

Background: The acromioclavicular (AC) capsule and ligament have been found to play a major role in maintaining horizontal stability. To reconstruct the AC capsule and ligament, precise knowledge of their anatomy is essential. Purpose/Hypothesis: The purposes of this study were (1) to determine the angle of the posterosuperior ligament in regard to the axis of the clavicle, (2) to determine the width of the attachment (footprint) of the AC capsule and ligament on the acromion and clavicle, (3) to determine the distance to the AC capsule from the cartilage border of the acromion and clavicle, and (4) to develop a clockface model of the insertion of the posterosuperior ligament on the acromion and clavicle. It was hypothesized that consistent angles, attachment areas, distances, and insertion sites would be identified. Study Design: Descriptive laboratory study. Methods: A total of 12 fresh-frozen shoulders were used (mean age, 55 years [range, 41-64 years]). All soft tissue was removed, leaving only the AC capsule and ligament intact. After a qualitative inspection, a quantitative assessment was performed. The AC joint was fixed in an anatomic position, and the attachment angle of the posterosuperior ligament was measured using a digital protractor. The capsule and ligament were removed, and a coordinate measuring device was utilized to assess the width of the AC capsule footprint and the distance from the footprint to the cartilage border of the acromion and clavicle. The AC joint was then disarticulated, and the previously marked posterosuperior ligament insertion was transferred into a clockface model. The mean values across the 12 specimens were demonstrated with 95% CIs. Results: The mean attachment angle of the posterosuperior ligament was 51.4° (95% CI, 45.2°-57.6°) in relation to the long axis of the entire clavicle and 41.5° (95% CI, 33.8°-49.1°) in relation to the long axis of the distal third of the clavicle. The mean clavicular footprint width of the AC capsule was 6.4 mm (95% CI, 5.8-6.9 mm) at the superior clavicle and 4.4 mm (95% CI, 3.9-4.8 mm) at the inferior clavicle. The mean acromial footprint width of the AC capsule was 4.6 mm (95% CI, 4.2-4.9 mm) at the superior side and 4.0 mm (95% CI, 3.6-4.4 mm) at the inferior side. The mean distance from the lateral clavicular attachment of the AC capsule to the clavicular cartilage border was 4.3 mm (95% CI, 4.0-4.6 mm), and the mean distance from the medial acromial attachment of the AC capsule to the acromial cartilage border was 3.1 mm (95% CI, 2.9-3.4 mm). On the clockface model of the right shoulder, the clavicular attachment of the posterosuperior ligament ranged from the 9:05 (range, 8:00-9:30) to 11:20 (range, 10:00-12:30) position, and the acromial attachment ranged from the 12:20 (range, 11:00-1:30) to 2:10 (range, 13:30-14:40) position. Conclusion: The finding that the posterosuperior ligament did not course perpendicular to the AC joint but rather was oriented obliquely to the long axis of the clavicle, in combination with the newly developed clockface model, may help surgeons to optimally reconstruct this ligament. Clinical Relevance: Our results of a narrow inferior footprint and a short distance from the inferior AC capsule to cartilage suggest that proposed reconstruction of the AC joint capsule should focus primarily on its superior portion.

The Role of the Acromioclavicular Ligament in Acromioclavicular Joint Stability: A Cadaveric Biomechanical Study.

Background:Acromioclavicular (AC) joint dislocation is evaluated using the radiologically based Rockwood classification. The relationship between ligamentous injury and radiological assessment is still controversial.Purpose/Hypothesis:To investigate how the AC ligament and trapezoid ligament biomechanically contribute to the stability of the AC joint using cadaveric specimens. The hypothesis was that isolated sectioning of the AC ligament would result in increased instability in the superior direction and that displacement >50% of the AC joint would occur.Study Design:Controlled laboratory study.Methods:Six shoulders from 6 fresh-frozen cadavers were used in this study. Both the scapula and sternum were solidly fixed on a customized wooden jig with an external fixator. We simulated distal clavicular dislocation with sequential sectioning of the AC and coracoclavicular (CC) ligaments. Sectioning stages were defined as follows: stage 0, the AC ligament, CC ligament, and AC joint capsule were left intact; stage 1, the anteroinferior bundle of the AC ligament, joint capsule, and disk were sectioned; stage 2, the superoposterior bundle of the AC ligament was sectioned; and stage 3, the trapezoid ligament was sectioned. The distal clavicle was loaded with 70 N in the superior and posterior directions, and the magnitudes of displacement were measured.Results:The amounts of superior displacement averaged 3.7 mm (stage 0), 3.8 mm (stage 1), 8.3 mm (stage 2), and 9.5 mm (stage 3). Superior displacement >50% of the AC joint was observed in stage 2 (4/6; 67%) and stage 3 (6/6; 100%). The magnitudes of posterior displacement were 3.7 mm (stage 0), 3.7 mm (stage 1), 5.6 mm (stage 2), and 9.8 mm (stage 3). Posterior displacement >50% of the AC joint was observed in stage 3 (1/6; 17%).Conclusion:We found that the AC ligaments contribute significantly to AC joint stability, and superior displacement >50% of the AC joint can occur with AC ligament tears alone.Clinical Relevance:The AC ligament plays an important role not only in horizontal stability but also in vertical stability of the AC joint.

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.].

Innervation of the acromioclavicular joint by the suprascapular nerve.

The suprascapular nerve is largely responsible for the majority of the sensory innervation of the acromioclavicular joint. In this anatomical study, we describe, in detail, the anatomy of the sensory innervation of the acromioclavicular joint by the branches of the suprascapular nerve. Twenty-seven shoulders from 17 cadaveric specimens were carefully dissected to identify the course of the suprascapular nerve, with the main focus being on the sensory innervation of the acromioclavicular joint. Nine specific measurements of the acromioclavicular joint sensory nerves were made of each shoulder in relation to distinct anatomical landmarks to determine the mean location and course of these nerves. In all 27 shoulders (100%), a sensory branch to the acromioclavicular joint with a proximal origin from the suprascapular nerve could be depicted ("first sensory branch"). The mean length of this branch was 4.3 cm (range: 3.3-5.3 cm). In 14 shoulders (52%), a further sensory branch of the suprascapular nerve innervating the posterior acromioclavicular joint capsule could be identified ("second sensory branch"). A detailed anatomical description of the sensory innervation of the acromioclavicular joint from suprascapular nerve branches was performed, which can potentially aid in the development of more focused anesthetic blockades and acromioclavicular joint denervation procedures.

Acromioclavicular Joint Stabilization: A Biomechanical Study of Bidirectional Stability and Strength.

Background:It is important to restore horizontal and vertical stability to the acromioclavicular (AC) joint when treating dislocations of this joint. Most surgical stabilization techniques of the AC joint have primarily addressed the coracoclavicular ligament complex; however, these techniques may not satisfactorily restore horizontal stability to the AC joint.Purpose:To evaluate the strength and bidirectional stability of 3 AC joint stabilizing techniques in a cadaveric model.Study Design:Controlled laboratory study.Methods:A total of 24 cadaveric shoulders were randomly allocated to 3 treatment groups. For each group, a standardized AC joint stabilizing procedure was performed, and the specimens were potted for mechanical testing. The following reconstruction techniques were used: a single clavicular tunnel for group A, a double clavicular tunnel for group B, and a double clavicular tunnel plus suture fixation across the AC joint for group C. The specimens underwent cyclic loading in the horizontal and vertical planes and then load to failure. Eight control specimens also underwent cyclic loading in both planes. Construct stiffness during cyclic loading, change in displacement after cyclic loading in both planes, load to failure in the vertical plane, and mode of failure were evaluated, and stiffness was compared among the treatment groups as well as with a control group.Results:There was a decrease in joint stiffness for all groups, including controls, during the cyclic loading. Compared with controls, all 3 treatment groups demonstrated equivalent stiffness and displacement in the vertical plane. In the horizontal plane, all 3 treatment groups demonstrated decreased stiffness, increased displacement, or both when compared with controls. When groups were compared, no treatment arm proved superior regarding stiffness or displacement in either plane. Load-to-failure testing of the 3 treatment groups in the vertical plane demonstrated construct strength and stiffness comparable with reports for the native AC joint. The mode of failure was predominantly fracture at the point of fixation to the testing apparatus.Conclusion:There was no difference in bidirectional strength and stability between the single– and double–clavicular tunnel techniques of coracoclavicular reconstruction. The addition of a stabilizing suture across the AC joint does not improve horizontal stability in the absence of repair of the AC joint capsule and deltotrapezial fascia.Clinical Relevance:This laboratory study provides further evidence of the importance of the AC joint capsule and associated soft tissues in affording horizontal stability to that joint. Information from this and subsequent studies utilizing a bidirectional model can influence the choice of surgical procedure in the clinical treatment of AC joint dislocations.

Ultrasound-Guided Prolotherapy for Acromial Enthesopathy and Acromioclavicular Joint Arthropathy: A Single-Arm Prospective Study.

Prolotherapy is an injection-based complementary treatment for various musculoskeletal diseases. The aim of this study was to evaluate the therapeutic efficacy of ultrasound-guided prolotherapy in the treatment of acromial enthesopathy and acromioclavicular joint arthropathy. Thirty-one patients with chronic moderate-to-severe shoulder pain were recruited from September 2015 to September 2017. Ultrasound-guided prolotherapy was performed by injecting 10 mL of a 15% dextrose solution into the acromial enthesis of the deltoid or acromioclavicular joint capsule aseptically. Prolotherapy was given in 2 sessions separated by a 1-month interval. The pretreatment-to-posttreatment change in the pain visual analog scale (VAS) score was recorded as the primary outcome. The mean follow-up duration was 61.8 days. A paired t test was used to assess the difference in pretreatment and posttreatment VAS scores. A univariate logistic regression analysis was conducted to identify the demographic variables associated with substantial pain reduction after the intervention. Substantial pain reduction was defined as a posttreatment VAS score of 3 or less. Twenty of the 31 patients reported substantial pain reduction without adverse effects after the intervention. The mean VAS score reduction ± SD was 4.3 ± 2.6 (pretreatment, 6.8 ± 1.5; posttreatment, 2.5 ± 2.1; P < .01). Ultrasound-guided prolotherapy with a 15% dextrose solution is an effective and safe therapeutic option for moderate-to-severe acromial enthesopathy and acromioclavicular joint arthropathy.

Biomechanical Evaluation of a Single- Versus Double-Tunnel Coracoclavicular Ligament Reconstruction With Acromioclavicular Stabilization for Acromioclavicular Joint Injuries

Background: An anatomic double-tunnel (DT) reconstruction technique has been widely adopted to reconstruct the ruptured coracoclavicular (CC) ligaments seen with high-grade acromioclavicular (AC) joint injuries. However, the anatomic DT reconstruction has been associated with the risk of clavicle fractures, which may be problematic, particularly for contact athletes. Purpose/Hypothesis: The purpose was to compare a single-tunnel (ST) CC ligament reconstruction for AC joint injuries with the native state as well as with the more established anatomic DT CC ligament reconstruction. The hypothesis was that ST CC ligament reconstruction would demonstrate biomechanical properties similar to those of the native state and the DT CC ligament reconstruction. Study Design: Controlled laboratory study. Methods: Eighteen fresh-frozen human cadaveric shoulders (9 matched pairs) with mean ± SD age of 55.5 ± 8.5 years underwent biomechanical testing. One specimen of each matched pair underwent a ST CC ligament reconstruction and the second, a DT CC ligament reconstruction. The ST and DT CC ligament reconstruction techniques involved a 5-mm distal clavicle excision, avoided coracoid drilling, and utilized a 3.0-mm suture anchor to fix the excess lateral limb to reconstruct the superior AC joint capsule. The ST CC ligament reconstruction technique additionally included a 1.3-mm suture tape to help avoid a sawing effect, as well as a dog-bone button over the clavicular tunnel to increase stability of the construct. All specimens were tested to 70 N in 3 directions (superior, anterior, and posterior) in the intact and reconstructed states. The ultimate load, yield load, stiffness, and mode of failure of the reconstructed specimens were tested. Results: There were no significant differences in translation at 70 N in the superior (P = .31), anterior (P = .56), and posterior (P = .35) directions between the ST CC ligament reconstruction and the intact state. The ultimate load to failure, yield load, and stiffness in the ST and DT groups were also not significantly different. There were no distal clavicle fractures in load-to-failure testing in the ST or DT group. Conclusion: In this biomechanical study, ST CC ligament reconstruction demonstrates biomechanical properties comparable to the intact state. Additionally, use of the ST CC ligament reconstruction shows biomechanical properties similar to the DT CC ligament reconstruction technique while theoretically posing less risk of clavicle fracture. Clinical Relevance: This study suggests that the ST CC ligament reconstruction has biomechanical properties equivalent to the DT CC ligament reconstruction with less theoretical risk of clavicle fracture.

Arthroscopically Assisted Treatment of Acute Dislocations of the Acromioclavicular Joint

Arthroscopically assisted treatments for dislocations of the acromioclavicular joint combine the advantages of exact and visually controlled coracoid tunnel placement with the possibility of simultaneous treatment of concomitant injuries. The clinical results of previous arthroscopically assisted techniques have been favorable at midterm and long-term follow-up. The presented surgical technique combines the advantages of arthroscopically positioned coracoclavicular stabilization with an additional suture cord cerclage of the acromioclavicular joint capsule for improved horizontal stability.

All-Arthroscopic Technique for Reconstruction of Acute Acromioclavicular Joint Dislocations

Acromioclavicular joint dislocations are a common injury particularly among contact sports players. There has been an increasing trend toward arthroscopic management of these injuries. To date, these reconstructions have primarily addressed superoinferior instability by reconstructing the coracoclavicular ligaments. We describe an all-arthroscopic technique for reconstruction of the coracoclavicular ligaments using Arthrex ABS TightRopes (Arthrex, Naples, FL), with additional stabilization of the superior acromioclavicular joint capsule using an anchor-based suture bridge to address anteroposterior instability.

Continuous Loop Double Endobutton Reconstruction for Acromioclavicular Joint Dislocation

Background: Current anatomic methods for reconstruction of the dislocated acromioclavicular (AC) joint show improved clinical results but continue to be associated with significant rates of fixation loss and complications, limiting more widespread use. Purpose: To determine the long-term clinical and radiologic outcomes of a novel surgical technique using a closed-loop double Endobutton device to reconstruct both acute and chronic dislocations. Study Design: Case series; Level of evidence, 4. Methods: Between 2003 and 2012, a total of 35 patients (31 men, 4 women) at a mean age of 42 years (range, 25-70 years) were surgically treated for a Rockwood type III or greater AC joint dislocation with the described technique (26 chronic, 9 acute). Imbrication of the AC joint capsule and deltotrapezial fascia was performed in all patients. Biological bridging across the coracoclavicular (CC) interval was performed in all patients by use of coracoacromial (CA) ligament transfer in 28 patients and primary repair of the CC ligament in 7 patients. Complete follow-up information was obtained for 31 of 35 patients. Results: At a mean follow-up of 5.2 years (range, 27-144 months), the construct remained stable in all but 1 patient. The mean CC interval difference was 1.1 mm (range, –2.5 to 4.0 mm) and was <2 mm in 87% of patients. The mean Constant score was 98; the mean University of California, Los Angeles Shoulder Rating Scale score was 34; and the mean American Shoulder and Elbow Surgeons Shoulder Score was 98. Follow-up MRI evaluation in 10 patients consistently demonstrated a wide band of dense scar tissue between the coracoid and clavicle. No infections, fractures, or perioperative complications occurred. Conclusion: Excellent results were obtained and maintained over long-term follow-up. The continuous loop device eliminated the possibility of knot slippage or breakage. MRI confirmed a robust healing response. The described technique resulted in outcomes that were significantly superior to historical reports of nonsurgical outcomes, and the technique can be recommended both for acute and chronic dislocations.

Acromioclavicular joint instability: anatomy, biomechanics and evaluation.

Acromioclavicular (AC) joint instability is a common source of pain and disability. The injury is most commonly a result of a direct impact to the AC joint. The AC joint is surrounded by a capsule and has an intra-articular synovium and an articular cartilage interface. An articular disc is usually present in the joint, but this varies in size and shape. The AC joint capsule is quite thin, but has considerable ligamentous support; there are four AC ligaments: superior, inferior, anterior and posterior. The coracoclavicular (CC) ligament complex consists of the conoid and trapezoid ligaments. They insert on the posteromedial and anterolateral region of the undersurface of the distal clavicle, respectively. The coracoid origin of the trapezoid covers the posterior half of the coracoid dorsum; the conoid origin is more posterior on the base of the coracoid. Several biomechanical studies showed that horizontal stability of the AC joint is mediated by the AC ligaments while vertical stability is mediated by the CC ligaments. The radiographic classification of AC joint injuries described by Rockwood includes six types: in type I injuries the AC ligaments are sprained, but the joint is intact; in type II injuries, the AC ligaments are torn, but the CC ligaments are intact; in type III injuries both the AC and the CC ligaments are torn; type IV injuries are characterized by complete dislocation with posterior displacement of the distal clavicle into or through the fascia of the trapezius; type V injuries are characterized by a greater degree of soft tissue damage; type VI injuries are inferior AC joint dislocations into a subacromial or subcoracoid position. The diagnosis of AC joint instability can be based on historical data, physical examination and imaging studies. The cross body adduction stress test has the greatest sensitivity, followed by the AC resisted extension test and the O'Brien test. Proper radiographic evaluation of the AC joint is necessary. The Zanca view is the most accurate view for examining the AC joint. The axial view of the shoulder is important in differentiating a type III AC joint injury from a type IV injury.