Reconstruction of the Acromioclavicular Ligament Complex Using Dermal Allograft: A Biomechanical Analysis

Comparison of clinical efficacy between reconstruction of the superior acromioclavicular ligament with acellular dermal allografts and clavicular hook plate in acromioclavicular dislocations

PURPOSES

We aimed to compare the clinical efficacy of superior acromioclavicular ligament reconstruction (SALR) using acellular dermal allograft with that of clavicular hook plate fixation (HP) in patients with acromioclavicular (AC) dislocations. We hypothesized that the SALR could provide more stability than hook plate.

METHODS

Twenty-two cases of acute AC joint dislocation between November 2021 to December 2023 were retrospectively reviewed. All patients were divided into 2 groups based on the treatment with SALR (12 cases) or HP (10 cases). Patients were evaluated radiologically and clinically using coracoclavicular distance and ratio, pain visual analogue scale (PVAS), Single Assessment Numerical Evaluation (SANE), and American Shoulder and Elbow Surgeons (ASES) at postoperative 3 months and 1 year. We evaluated whether patient achieve MCID of PVAS at the last visit, based on the minimal clinically important differences (MCIDs) of PVAS.

RESULTS

The SALR group showed a lower rate of reduction loss (8.3 % vs. 40.0 %) and similar clinical outcomes compared to the hook plate group. Initial SANE score was statistically significantly lower in SALR group (SANE: SALR, 45.8 ± 20.7; HP, 68.0 ± 15.5, p = 0.009), but there were no significant differences in final clinical outcomes, including PVAS, ASES, and SANE scores.

CONCLUSION

SALR with acellular dermal allograft demonstrates comparable clinical outcomes to hook plate fixation and may offer a viable alternative, especially in complicated cases.

STUDY DESIGN

Case series; Level of evidence, 4.

Clavicular tunnel widening after coracoclavicular stabilization surgery: a systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis aimed to (1) estimate the prevalence of clavicular tunnel widening (TW) after coracoclavicular stabilization surgery and its risk factors and (2) assess whether TW is correlated with clavicle fracture or loss of reduction of the acromioclavicular joint (ACJ).

METHODS

In January 2023, 3 electronic databases were searched to collect data on postoperative clavicular TW, its prevalence, magnitude, and correlation with fracture and ACJ loss of reduction. Studies were classified according to the time of surgical intervention, and the clavicular tunnels were categorized by their anatomic location. Mean differences were calculated using a DerSimonian-Laird random-effects model, while binomial outcomes were pooled using the Freeman-Tukey double arcsine transformation. Univariate and multivariate meta-regression analyses were performed to determine the effect of several variables on the proportion of cases with TW.

RESULTS

Fifteen studies (418 shoulders) were included. At the final follow-up, evidence of clavicular TW was found in 70% (95% confidence interval [CI]: 70%-87%; I2 = 89%) of 221 shoulders. Surgeries in acute cases had a lower prevalence of TW (52%) compared to chronic cases (71%) (P < .001). Significant TW was found in the central tunnel (3.2 mm; 95% CI: 1.8-4.6 mm; P < .001; I2 = 72%) for acute injuries and in the medial (1.2 mm; 95% CI: 0.7-1.7 mm; P < .001; I2 = 77%) and lateral (1.5 mm; 95% CI: 0.7-2.3 mm; P < .001; I2 = 77%) tunnels for chronic cases. Single central-tunnel techniques were positively associated with the prevalence of TW (P = .046), while biotenodesis screw fixation was associated with a lower prevalence (P = .004) in chronic cases. Reconstruction of the ACJ ligament complex with tendon grafts or sutures was associated with a higher prevalence of TW (P < .001). Drill sizes between 2.5 and 5 mm were significantly associated with a lower prevalence of TW, regardless of injury chronicity (P = .012). No correlation was found between TW and the loss of ACJ reduction or clavicle fractures.

CONCLUSIONS

This systematic review and meta-analysis explored TW occurrence following coracoclavicular stabilization surgery. TW was observed in 70% of patients at final follow-up, with a higher prevalence in chronic than in acute cases. Modifiable surgical variables, such as single-tunnel tendon graft constructs for acute or chronic injuries and knotted graft procedures for chronic injuries, were significantly associated with TW. Furthermore, the prevalence of TW increased with concomitant surgical treatment of the ACJ ligament complex, and decreased with drill sizes between 2.5 and 5 mm, regardless of lesion chronicity. These surgical variables should be considered when establishing transosseous tunnels for coracoclavicular stabilization. Clavicle fractures and TW mechanisms require further investigation.

Arthroscopically Assisted Tensionable Cerclage Reconstruction of an Acromioclavicular Separation With Combined Fixation of the Coracoclavicular and Acromioclavicular Ligaments

A variety of surgical techniques are currently available to manage high-grade acromioclavicular (AC) separations, including hook plates/wires, nonanatomic ligament reconstruction, and anatomic cerclage with or without biological augmentation. Traditional reconstructions focused on the coracoclavicular ligaments alone and often were associated with high rates of recurrent deformity. Biomechanical and clinical data have suggested that additional fixation of the AC ligaments is beneficial. This Technical Note describes an arthroscopically assisted approach for combined reconstruction of the coracoclavicular and AC ligaments with a tensionable cerclage.

Evaluation of the coracoid bone tunnel placement on Dog Bone™ button fixation for acromioclavicular joint dislocation: a cadaver study combined with finite element analysis

BACKGROUND

Dog Bone™ button fixation is frequently used to treat acromioclavicular joint (ACJ) dislocation. However, various studies have reported complications after fixation.

OBJECTIVE

To investigate the effect of the coracoid bone tunnel location on the treatment of ACJ dislocation through single-tunnel coracoclavicular (CC) ligament fixation with the Dog Bone™ button.

METHODS

Six cadaveric shoulders were used. Each specimen was subjected to five testing conditions in the following order: (1) normal ACJ (Gn); (2) acromioclavicular and CC ligaments were removed (G0); (3) CC ligament reconstruction was performed using the Dog Bone™ technique, and the coracoid bone tunnel was at the center of the coracoid base (G1); (4) reconstruction was performed at 5 mm distal from the G1 site, along the axis of the coracoid (G2); (5) reconstruction was performed at 10 mm distal from the G1 site, along the axis of the coracoid (G3). The angles of pronation and supination of the clavicle under the same load (30 N) were measured. Next, a finite element (FE) model was created using computed tomography (CT) images of the normal shoulder. Model 1 (M1), model 2 (M2), and model 3 (M3) correspond to G1, G2, and G3, respectively. A force of 70 N was applied as a vertical upward load to the distal clavicle. Subsequently, the von Mises stress, the strain LE along the FiberWire, and the displacement nephogram of the three models were obtained.

RESULTS

After single-tunnel CC ligament fixation using the Dog Bone™ technique, the clavicle in the G2 group (20.50 (19.50, 21.25) °, 20.00 (18.75, 21.25) °) had the best rotational stability. The peak von Mises stress, the strain LE along the FiberWire, and the maximum displacement were smaller in M2 than in M1 and M3.

CONCLUSIONS

When the coracoid bone tunnel was located 5 mm anterior to the center of the coracoid base (along the axis of the coracoid), the clavicle showed greater rotational stability.

Acromioclavicular reconstruction techniques after acromioclavicular joint injuries: A systematic review of biomechanical studies

BACKGROUND

Residual horizontal instability after surgical treatment for acromioclavicular joint injuries is seen as a potential cause of suboptimal clinical outcomes. Biomechanical studies have demonstrated that the acromioclavicular capsule/ligaments are the primary restraints for anteroposterior translation. However, limited studies have addressed the biomechanics of a reconstruction of the acromioclavicular capsule/ligaments. The aim of this systematic review was to evaluate the biomechanical role of acromioclavicular capsule/ligament reconstruction techniques after an acromioclavicular joint injury.

METHODS

A search was carried out on the databases Medline and EMBASE, and was conducted according to the PRISMA guidelines. Biomechanical studies addressing horizontal and vertical displacement or joint stiffness after reconstructing the acromioclavicular capsule/ligament with or without coracoclavicular ligament reconstruction, were included.

FINDINGS

Nineteen studies were included in this review after screening and eligibility assessment. Five of them investigated different sole acromioclavicular capsule/ligament reconstruction techniques. In 10 studies, a sole coracoclavicular ligament reconstruction was compared to a coracoclavicular ligament reconstruction with additional acromioclavicular capsule/ligament reconstruction. The remaining 4 studies compared different acromioclavicular capsule/ligament with coracoclavicular reconstruction techniques with each other.

INTERPRETATION

Several testing protocols to evaluate acromioclavicular capsule/ligament reconstruction have been described and can make it difficult to compare the results of the different studies. Acromioclavicular capsule/ligament reconstruction may provide increased anteroposterior and rotational stability but an optimal reconstruction technique, which mimics all biomechanical characteristics of the native joint is not yet available.

Reconstruction of the Acromioclavicular Joint Using a Double Augmentation With Hamstrings Tendon and Dermal Graft

The purpose of this article is to describe a technique to restore both vertical and horizontal stability using an augmentation of the acromioclavicular ligament complex (ACLC) and coracoclavicular (CC) ligaments with the combination of synthetic and biological support. Our technique introduces a modification in the surgical procedure for acromioclavicular (AC) joint dislocations; it provides the use of biological supplements not only during the repair of the CC ligaments but also when the ACLC is restored due to the use of a dermal patch as an augmentation allograft after the use of a horizontal cerclage. The main purpose of this technique is to replicate the anatomy and functionality of the native ligaments that stabilize the AC joint to improve both clinical and functional results.

Combination of Surgical Techniques Restores Multidirectional Biomechanical Stability of Acromioclavicular Joint

PURPOSE

To measure the multiaxial stability of the acromioclavicular joint before and after transection of the acromioclavicular capsule and coracoclavicular ligaments and after sequential repair of acromioclavicular and coracoclavicular ligaments.

METHODS

Biomechanical testing was performed on fresh-frozen human cadaveric shoulders (N = 6). Translational and rotational stability in the vertical and horizontal planes was measured in intact specimens, after transecting the acromioclavicular and coracoclavicular ligaments, and after sequentially performing the following procedures: single-bundle coracoclavicular repair (CCR), modified Weaver-Dunn procedure (WD), and acromioclavicular stabilization (ACS).

RESULTS

Resecting the acromioclavicular and coracoclavicular significantly reduced translational stiffness in the inferior and anteroposterior directions, as well as rotational stiffness about the vertical and anteroposterior axes. All 3 surgical procedures increased inferior translational stiffness relative to the intact condition (Intact: 38 ± 9 N/mm, CCR: 54 ± 23 N/mm (P = .03), CCR+WD 52 ± 20 N/mm (P = .07), CCR ± WD+ACS 50 ± 21 N/mm (P = .17)). However, the combination of CCR, modified WD, and ACS resulted in the greatest increase in stiffness in internal rotation (Intact: 12.5 ± 7.4 cNm/deg, CCR: 1.2 ± 1.1 cNm/deg, CCR+WD 7.2 ± 3.0 N∗m/deg [P = .023], CCR+WD+ACS 11.6 ± 4.9 cNm/deg [P = .055]).

CONCLUSIONS

The cumulative stability of CCR, WD reconstruction, and ACS appears to be additive. Our findings provide a biomechanical justification for combining all three techniques. Biomechanical studies assessing the performance of various acromioclavicular repairs and reconstructions should therefore incorporate multiaxial testing in their protocols.

CLINICAL RELEVANCE

Multiple points of fixation that provide multidirectional stability have the potential to improve clinical outcomes and reduce failure rates of acromioclavicular joint repair or stabilization.

All-Arthroscopic Coracoacromial Ligament Transfer: The Modified Neviaser Procedure for Acromioclavicular Dislocations

Over the course of the years, the topic of optimizing the management of acromioclavicular joint dislocations has gained popularity, remaining a subject of debate. It has been determined that posterior horizontal instability appears to be one of the factors influencing both clinical and radiographic outcomes, postsurgical reconstructions with coracoclavicular techniques. In contrast, the acromioclavicular ligament complex (ACLC) has been experimentally demonstrated to play a crucial role in horizontal translation and rotational stability of the clavicle. Although several strategies have been established, perfect surgical timing, and its potential impact during the healing process, remain poorly defined. Furthermore, appropriate surgical techniques to restore normal acromioclavicular joint kinematics while ensuring an adequate biological environment remain unclear. Due to the existence of multiple features present in acromioclavicular joint reconstruction techniques, an ideal approach involves ACLC and coracoclavicular combination reconstruction, minimal clavicular drilling, and biological enhancement to ensure anatomical reduction and an adequate process of ligament healing. The purpose of this Technical Note is to present a modified surgical technique of the Neviaser procedure. This modified surgical technique combines an all-arthroscopic single tunnel coracoclavicular fixation with the transfer of the coracoacromial ligament to reconstruct the ACLC.

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

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

CLINICAL RELEVANCE

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.

Comparison of the TightRope system versus hook plate in acute acromioclavicular joint dislocations: a retrospective analysis

This study compared the results of the minimally invasive coracoclavicular (CC) fixation with a single TightRope (MITR) procedure and the hook plate (HP) procedure for acute acromioclavicular (AC) joint dislocation treatment. Sixteen patients with a mean age of 44.9 ± 11 years were treated with the MITR procedure. Nineteen patients with a mean age of 40.2 ± 8.7 years were treated using the HP procedure. Clinical outcomes were evaluated with the Visual Analog Scale (VAS) for pain, Constant–Murley Score (CMS), and University of California at Los Angeles (UCLA) Shoulder score. Vertical displacement of the clavicle with reference to the height of the acromion was measured in standard anteroposterior radiographs. The mean follow-up was 27 months in the MITR group and 30 months in the HP group. No statistically significant differences were found between the MITR group and the HR group in terms of VAS score (0.4 ± 0.6 vs 0.7 ± 0.6, P = 0.138), UCLA Shoulder score (33.9 ± 2.5 vs 33.7 ± 1.5, P = 0.843), or CMS (95.7 ± 7.3 vs 93.7 ± 6.6, P = 0.400). No redislocation was identified in the HP group, while redislocation occurred in 1 of 16 (6.3%) patients in the MITR group. One patient in the HP group (5.3%) had acromial osteolysis, while no acromial osteolysis was found in the MITR group. No other adverse events, such as infections, tunnel widening, fractures, or implant-related complications, were observed. Both procedures provided satisfactory results. The HP procedure provided better reduction, while the MITR procedure provided a slightly lower tendency of pain. Long-term follow-up is needed to investigate the clinical outcomes and radiological outcomes of both groups.

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.

Nonanatomic and Suture-Based Coracoclavicular Joint Stabilization Techniques Provide Adequate Stability at a Lower Cost of Implants in Biomechanical Studies When Compared With Anatomic Techniques: A Systematic Review and Meta-Analysis

Purpose

To compare the stability and cost of the used implants in nonanatomic and anatomic acromioclavicular joint repair/reconstruction (ACCR) techniques tested in cadaveric shoulder biomechanical studies during the last decade.

Methods

A systematic review and meta-analysis were performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and prospectively registered in PROSPERO. Two independent reviewers searched PubMed, Embase, and Virtual Health Library databases. Studies evaluating 3-direction stability under 70-N loads and load-to-failure protocols with servohydraulic testing systems were included. A meta-analysis of the mean differences of anterior, posterior, and superior direction; relative stability value in 3 directions; superior direction load-to-failure; stability/cost index; and load-to-failure/cost index was performed using a continuous random-effects model and 95% confidence interval.

Results

Eighteen articles were included. Both non-ACCR and ACCR techniques exceeded the minimum acceptable threshold of stability and load-to-failure. ACCR techniques were biomechanically better in terms of anterior stability (P = .04) and relative stability value (mean difference 64.08%, P = .015). However, supraphysiological stability and failure loads were achieved with non-ACCR techniques at a lower cost of implants. Techniques combining 2 clavicular tunnels separated by at least 10 mm, a mean of 2 sutures, and/or suture tapes had the greatest stability/cost index and load-to-failure/cost index among the included techniques (confidence interval 99%).

Conclusions

Non-ACCR and ACCR techniques exceeded the minimum acceptable threshold of stability and failure loads in controlled biomechanical testing. However, non-ACCR and techniques combining 2 clavicular tunnels separated by at least 10 mm, a mean of 2 sutures, and/or suture tapes provide supraphysiologic stability and failure loads at a lower cost of implants.

Clinical Relevance

Non-ACCR and suture-based techniques may provide more cost-effective and greater value treatment for acromioclavicular joint injury and could be considered in the surgical management of normal activity individuals and cost-sensitive populations.

Arthroscopic-Assisted Acromioclavicular Joint Dislocation Repair: A Modified Technique for Horizontal Stabilization Using Suture Anchors

Acromioclavicular (AC) dislocation is a common lesion often resulting from a sports injury. Nowadays, treatment is still controversial mainly in grade III lesions according to the Rockwood classification. For most surgically treated AC acute dislocations, treatment is performed with an arthroscopic procedure that anatomically reconstructs the coracoclavicular ligaments. Increasing knowledge about AC joint biomechanics has underlined the importance of its horizontal stability through the superior and inferior AC ligaments. Moreover, the pattern of lesion tends to repeat itself, with the superior AC ligament being torn most frequently from the clavicular side in a peeling fashion. Therefore, the purpose of this note is to describe the technical aspects of additional horizontal stability through superior AC ligament repair using suture anchors.

Novel Double Endobutton Technique Combined with Three-Dimensional Printing: A Biomechanical Study of Reconstruction in Acromioclavicular Joint Dislocation

Objective

To reconstruct the acromioclavicular (AC) joint using an adjusted closed‐loop double Endobutton technique via a guiding locator that was applied using three‐dimensional (3D) printing technology. At the same time, the reliability and safety of the novel double Endobutton (NDE) were tested by comparing the biomechanics of this technique with the TightRope (TR) approach.

Methods

This retrospective study was conducted between January 2017 and January 2019. The Department of Anatomy at Southern Medical University obtained 18 fresh‐frozen specimens (8 left and 10 right; 12 men and 6 women). First, the guiding locators were applied using 3D printing technology. After preparation of materials, specimens were divided into an NDE group, a TR group, and a normal group. In the NDE and TR groups, the navigation module was used to locate and establish the bone tunnels; after that, the NDE or TR was implanted. However, the Endobuttons were fixed while pressing the distal clavicle downwards and the length of the loop could be adjusted by changing the upper Endobutton in the NDE group while the suture button construct was tensioned and knotted after pressing down the distal clavicle in the TR. Finally, load testing in anterior–posterior (AP), superior–inferior (SI), and medial–lateral (ML) directions as well as load‐to‐failure testing in the SI direction were undertaken to verify whether the NDE or TR had better biomechanics.

Results

In the load testing, the displacements of the NDE and TR groups in the AP, SI, and ML direction were significantly shorter than those of the normal group (P < 0.05). In the load‐to‐failure testing, the ultimate load of the NDE and TR groups had significantly higher increases than the normal group (722.16 ± 92.04 vs 564.63 ± 63.05, P < 0.05; 680.20 ± 110.29 vs 564.63 ± 63.05, P < 0.05). However, there was no statistically significant difference between the two techniques for these two tests (P > 0.05). In the NDE group, four of six failures were a result of tunnel fractures of the coracoid, while two of six were due to suture breakage. In the TR, three failures were due to coracoid tunnel fractures, one was a result of a clavicle tunnel fracture, and the rest were due to suture breakage. In the normal group, half of the failures were a result of avulsion fractures of the conical ligament at the point of the coracoid process, and the other three were due to rupture of the conical ligament, fracture of the distal clavicle, and fracture of the scapular body.

Conclusion

As for the TR technique, the stability and strength of the AC joint were better in patients who underwent reconstruction using the NDE technique than in the intact state.

Posterior Rotational and Translational Stability in Acromioclavicular Ligament Complex Reconstruction: A Comparative Biomechanical Analysis in Cadaveric Specimens

BACKGROUND

Persistent posterior instability of the acromioclavicular (AC) joint is a reported complication after isolated coracoclavicular (CC) reconstruction. Thus, multiple techniques have been proposed attempting to restore biomechanics of the AC ligament complex (ACLC).

PURPOSE/HYPOTHESIS

The purpose was to evaluate the posterior translational and rotational stability of an ACLC reconstruction with a dermal allograft (ACLC patch) as compared with 3 suture brace constructs. It was hypothesized that the ACLC patch would better restore AC joint posterior stability.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 28 cadaveric shoulders (mean ± SD age, 57.6 ± 8.3 years) were randomly assigned to 1 of 4 surgical techniques: ACLC patch, oblique brace, anterior brace, and x-frame brace. The force and torque to achieve 10 mm of posterior translation and 20° of posterior rotation of the AC joint were recorded in the following conditions: intact, transected ACLC, ACLC patch/brace repair, ACLC patch/brace repair with dissected CC ligaments, and ACLC patch/brace repair with CC ligament repair.

RESULTS

For posterior translation, transection of the ACLC reduced resistance to 16.7% of the native. With the native CC ligaments intact, the ACLC patch (59.1%), oblique brace (54.1%), and anterior brace (60.7%) provided significantly greater stability than the x-frame brace (33.2%; P < .001, P = .008, P < .001, respectively). ACLC patch, oblique brace, and anterior brace continued to have significantly higher posterior translational resistance than the x-frame (35.1%; P < .001, P = .003, P < .001) after transection and subsequent CC ligament repair. For posterior rotation, transection of the ACLC decreased the resistance to 5.4% of the intact state. With the CC ligaments intact, the ACLC patch (77.1%) better restored posterior rotational stability than the oblique (35.3%), anterior (48.5%), and x-frame (23.0%) brace repairs (P < .001, P = .002, P < .001). CC ligament transection and subsequent repair demonstrated the ACLC patch (41.0%) to have improved stability when compared with the oblique (16.0%), anterior (14.0%), and x-frame (12.7%) repairs (P = .006, P = .003, P = .002).

CONCLUSION

ACLC reconstruction with a dermal allograft better restored native posterior rotational stability than other brace constructs, with translational stability similar to the oblique and anterior brace technique at the time of surgery.

CLINICAL RELEVANCE

Horizontal stability of the AC joint is primarily controlled by the ACLC. Inability to restore AC joint biomechanics can result in persistent posterior instability and lead to functional impairment.

Optimal Management of Acromioclavicular Dislocation: Current Perspectives

Injuries to the acromioclavicular (AC) joint are common and mostly involve younger, male individuals. Whereas the majority of AC joint dislocations can be treated nonoperatively with a trial of immobilization, pain medication, cryotherapy, and physiotherapy, there are patients that do not respond well to conservative management and may require surgical treatment. Identifying and treating these patients according to the type and chronicity of AC joint dislocation is paramount. To date, a myriad of surgical techniques have been proposed to address unstable AC joint dislocations and are indicative of the uncertainty that exists in optimal management of these injuries. Historically research has focused on the restoration of the coracoclavicular ligament complex. However, recently the importance of the acromioclavicular capsule and ligaments has been emphasized. This review aims to provide the reader with an overview of current treatment strategies and research, as well as future perspectives.