Current concepts in the treatment of acromioclavicular joint dislocations

Outcomes of arthroscopic coracoclavicular management for acromioclavicular joint injuries: A systematic review

Introduction

Various surgical procedures for coracoclavicular (CC) ligament repair have been described for symptomatic acromioclavicular joint dislocations, with none emerging as a clear gold standard. There has been increased interest in arthroscopic approaches. This systematic review evaluates clinical outcomes after arthroscopic surgeries used to treat chronic and acute AC joint dislocations.

Methods

We searched three databases (PubMed, EMBASE, and OVID [MEDLINE]) from database inception to December 20, 2022. Studies were included if they met the following criteria: studies evaluating humans, English language studies, level of evidence I to IV, and studies investigating clinical outcomes in patients following arthroscopic surgery for coracoclavicular ligament reconstruction. Studies on open reconstruction techniques only were excluded. Primary outcomes included function/pain scores, coracoclavicular distances, complications, and revision rates.

Results

Fifty-two studies were included. In 33 studies, postoperative Constant-Murley scores ranged from 82.8 to 99 points. Postoperative VAS scores ranged from 0.3 to 4.1 in 16 studies. In 46 studies, revision rates ranged from 0 % to 44.4 %. We did not observe a difference in revision rates between chronic and acute cases (P = 0.268). Complications were more common in chronic than acute cases (25.5 % vs. 16.4 %; P < 0.001).

Conclusions

Arthroscopic surgery for chronic and acute CC ligament injuries exceeds the MCID and PASS for several outcomes, with low failure rates. Arthroscopic CC reconstruction is a safe and effective alternative for chronic AC joint dislocations.

Level of evidence

IV (Systematic Review of Level I-IV Studies).

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.

Anterior and coracoid base tunnel location combined with single -or double clavicular tunnel techniques using double-button fixation for coracoclavicular ligament reconstruction both restore horizontal stability. A biomechanical cadaver study

BACKGROUND

The placement of clavicle tunnels in coracoclavicular ligament reconstruction is well established, but the optimal position of the coracoid tunnel remains unclear. This study aimed to investigate how the coracoid tunnel's position affects horizontal stability during coracoclavicular ligament reconstruction using a double-button technique.

METHODS

Fifteen fresh frozen shoulder cadaver specimens were tested under various conditions: intact coracoclavicular ligaments, disrupted ligaments, and reconstructions with a single coracoid and clavicle tunnel or double clavicle tunnels. The coracoid tunnel was positioned at the coracoid base 1/9, and 1/5 anterior to the base. Specimens underwent displacement-controlled loading, with 2D motion analysis conducted on captured digital images using TEMA motion analysis.

FINDINGS

Mean displacement for intact coracoclavicular ligaments was 1.61 ± 0.92 mm, and 3.69 ± 1.09 mm for disrupted ligaments. For reconstructed conditions, displacements were as follows: Single-Tunnel Base (1.87 ± 0.64 mm), Single-Tunnel 1/9 (2.54 ± 1.13 mm), Single-Tunnel 1/5 (2.62 ± 1.17 mm), Double-Tunnel Base (1.25 ± 0.73 mm), Double-Tunnel 1/9 (2.03 ± 1.22 mm), and Double-Tunnel 1/5 (1.88 ± 1.20 mm). Differences among intact, reconstructed, and disrupted states were statistically significant (p = 0.01-0.0001), with all reconstruction techniques restoring horizontal displacement near the intact state.

INTERPRETATION

At point zero both single coracoid tunnel and single- and double-clavicle tunnel restored horizontal displacement to its intact state. Coracoid tunnel placement anterior to the base of the coracoid did not influence horizontal displacement but single coracoid at the coracoid base and single clavicle tunnel resulted in the most anatomic reconstruction. Single coracoid tunnel at the base and double-clavicle resulted in the most stable reconstruction.

Biomechanical comparison between low profile 2.7 mm distal locking hook plate and 3.5 mm distal locking hook plate for acromioclavicular joint injury: A finite element analysis

PURPOSE

Although hook plate fixation is popularly used, concerns exist regarding periprosthetic fractures and the necessity to remove the plate to prevent subacromial erosion and subsequent acromion fracture, due to its non-anatomical design. We hypothesized that a low profile 2.7 mm distal locking hook plate would provide comparable stability to a properly used 3.5 mm distal locking hook plate MATERIALS AND METHODS: A 3.5 mm distal locking plate (type 1) and a low profile 2.7 mm plate (type 2) were assessed by finite element analysis. Peak von Mises stress (PVMS) was calculated on the acromion's undersurface, clavicle shaft, and hook, focusing on how these stresses varied with the number and placement of distal locking screws.

RESULTS

Increased distal screws in both types led to lower PVMS on the acromion's undersurface and the hook, with the lowest acromion PVMS observed in type 2 with three distal screws, and on the hook in type 1 with two distal screws. Increasing the number of distal screws similarly reduced PVMS on the clavicle shaft, with the lowest in type 1 with two distal screws. In both plate types, the most posterior distal locking screw played a crucial role in distributing stress across the acromion and the hook.

CONCLUSION

The low profile 2.7 mm distal locking hook plate showed comparable biomechanical results to the 3.5 mm distal locking hook plate. Increasing the number of distal locking screws showed less stress concentration on the bone and hook in both models. The most posterior distal locking screw showed an essential role in stress distribution.

All-Endoscopic Treatment of Acute Acromioclavicular Joint Dislocation: Coracoclavicular Double Cerclage EndoButton Technique and Acromioclavicular Stabilization Using the Coracoacromial Ligament

High-grade the acromioclavicular joint (ACJ) dislocations can be treated surgically. Endoscopic techniques to stabilize the ACJ using an EndoButton suture technique for coracoclavicular (CC) fixation have been shown to be safe and reproducible. Several studies have demonstrated the benefit of stabilizing the ACJ to reduce postoperative horizontal instability. This Technical Note presents a full-endoscopic technique for acute ACJ dislocations using a double-stranded EndoButton cerclage technique for CC reconstruction and an additional coracoacromial ligament transfer for acromioclavicular reconstruction. An autologous coracoacromial ligament transfer to the lateral clavicle increases stability in the horizontal plane and reduces the risk of anteroposterior recurrent instability. Clinical studies need to show whether additive ACJ fixation in addition to the all-endoscopic double cerclage EndoButton CC stabilization technique is in fact beneficial.

Easy and safe: a new surgical fixation technique for acute and chronic anterior instabilities of the sternoclavicular joint: technique and results

BACKGROUND

Instabilities of the sternoclavicular (SC) joint are a rare injury, accounting for only 3% of all injuries of the shoulder girdle. Although acute posterior dislocations are an emergency and require immediate surgical intervention, anterior instabilities (first and second degree according to Allman) can mostly be treated conservatively. Chronic and highly instable acute anterior instabilities often impose a significant limitation on the lives of affected patients. Currently, there is no established therapeutic algorithm in place.

METHODS

This retrospective case series with prospective collection of data was performed at a level I trauma center. Patients treated surgically for anterior SC joint instabilities between January 2013 and December 2019 and with a minimum follow-up of 24 months were included. The injuries comprised 6 acute anterior dislocations treated with tape cerclage in a "figure-of-8" configuration; 12 patients with chronic anterior SC instabilities were treated with autologous tendon grafts. For 1 highly unstable chronic anterior instability, in addition to the tendon graft, synthetic suture material was applied. The clinical evaluation consisted of a physical examination and a standardized questionnaire, which included subjective and objective shoulder scores.

RESULTS

Of 24 patients, 19 (79%) with an average age of 32 ± 15 years were available for follow-up. A total of 63% of the patients were male. After a mean follow-up of 57 months, the mean age- and sex-adapted Constant-Murley Shoulder Score of acute anterior luxations amounted to 90 ± 20 points, the Nottingham Clavicle Score to 81 ± 22 points, and the Disability of the Arm, Shoulder and Hand Score to 11 ± 18 points. Chronic anterior instabilities had a mean Constant-Murley Shoulder Score of 90 ± 12 points, Nottingham Clavicle Score of 83 ± 17 points, and Disability of the Arm, Shoulder and Hand Score of 4 ± 5 points. The study shows a complication rate of 10%. Two patients underwent revision surgery.

CONCLUSIONS

To conclude, monocortical SC joint fixation in a "figure-of-8" fashion presents a low risk for complication and a low revision rate and can achieve an equally good functional outcome after the treatment of highly unstable acute and chronic anterior SC joint instabilities as other published techniques. Our approach presents less risk to the neurovascular structures of the mediastinum than other published techniques requiring bicortical drilling, therefore making the technique more accessible to hospitals without a cardiothoracic surgical background.

Tendon graft through the coracoid tunnel versus under the coracoid for coracoclavicular/acromioclavicular reconstruction shows no difference in radiographic or patient-reported outcomes

INTRODUCTION

The purpose of this prospective study was to report the outcomes of two different methods in CC and AC reconstruction for the treatment of AC separation using a tendon graft and knot-hiding titanium clavicular implant.

MATERIALS AND METHODS

Twenty-seven patients with Rockwood grade III and V acromioclavicular (AC) separations were randomized into two groups. The primary outcome was whether taking the tendon graft through the coracoid risked a fracture. The following were secondary outcomes: follow-up of clavicular wound healing and Nottingham Clavicle score, Constant score, and Simple Shoulder Test results obtained preoperatively and 24 months postoperatively. The anteroposterior radiographic change between the clavicular and coracoid cortexes and the clavicular tunnel diameter was measured postoperatively and 24 months postoperatively. General patient satisfaction with the outcome (poor, fair, good, or excellent) was assessed 2 years postoperatively.

RESULTS

No coracoid fractures were detected. No issues in clavicular wound healing were detected. The mean Nottingham Clavicle score increased from a preoperative mean of 42.42 ± 13.42 to 95.31 ± 14.20 (P < 0.00). The Constant score increased from a preoperative mean of 50.81 ± 17.77 to 96.42 ± 11.51 (P < 0.001). The Simple Shoulder Test score increased from a preoperative mean of 7.50 ± 2.45 to 11.77 ± 1.18 (P < 0.001). The changes were significant. The coracoclavicular distance increased from 11.88 ± 4.00 to 14.19 ± 4.71 mm (P = 0.001), which was significant. The clavicular drill hole diameter increased from 5.5 to a mean of 8.00 ± 0.75 mm. General patient satisfaction was excellent.

CONCLUSIONS

There were no significant differences between the two groups. There were no implant related complications in the clavicular wound healing. The results support the notion that good results are achieved by reconstructing both the CC and AC ligaments with a tendon graft.

STUDY REGISTRATION

This clinical trial was registered on Clinicaltrials.gov.

Acromioclavicular joint dislocation with loop double endobutton fixation assisted by orthopaedic surgery robot positioning system

OBJECTIVE

Acute acromioclavicular (AC) joint dislocation is a common orthopedic injury that can significantly impair shoulder function and reduce quality of life. Effective treatment methods are essential to restore function and alleviate pain. To investigate the short-term clinical efficacy of the minimally invasive closed-loop double endobutton fixation assisted by orthopaedic surgery robot positioning system (TiRobot) in the treatment of AC joint dislocation, and to evaluate its feasibility and safety.

METHODS

The clinical data of 19 patients with AC joint dislocation who underwent treatment with closed-loop double Endobutton fixation assisted by TiRobot between May 2020 and December 2022 were retrospectively analyzed. Visual Analog Scale (VAS) pain scores, the Constant Murley Score (CMS), and shoulder abduction range of motion were assessed and compared preoperatively and at the last follow-up. Computed tomography (CT) parameters of the acromioclavicular joint, including acromioclavicular distance (ACD), the distance between the upper and lower Endobutton (DED), the horizontal distance between the anterior edge of the distal clavicle and the anterior edge of the acromion (DACC), the diameter of the clavicular tunnel (DCT), and coracoid tunnel diameter (DC), were compared at 2 days, and 1 month after surgery, as well as at the last follow-up, along with the evaluation of intraoperative and postoperative complications.

RESULTS

The postoperative VAS, CMS, and shoulder-abduction range of motion were significantly improved compared with the preoperative (all, P<0.05). The statistical analysis showed no significant difference in the CT image parameters of the acromioclavicular joint at 2 days and 1 month after surgery(all, P>0.05). Comparisons of DCT and DC revealed statistically significant differences between the last follow-up and 1 month after surgery (P<0.05), and no statistically significant difference was found in ACD, DED, and DACC(all, P>0.05). There were no complications such as infection or vascular or neurological damage, no cases of rostral or clavicle fractures, loss of reduction, heterotopic ossification, shoulder stiffness, and no loosening or breaking of internal fixations.

CONCLUSION

Closed-loop double endobutton internal fixation assisted by TiRobot is an ideal method for the treatment of acute acromioclavicular (AC) joint dislocation. This method has the advantages of relatively simple operation, more accurate localization of bone tunnel during operation, less surgical trauma, and good recovery of shoulder function.

Comparative study of two different horizontal stabilisation methods in arthroscopically assisted coracoclavicular stabilisation for acute acromioclavicular joint dislocations-Good clinical outcome and no correlation to recurrent anteroposterior instability

PURPOSE

The hypothesis of this study was that acromioclavicular K-wire transfixation is noninferior to horizontal FiberTape cerclage in terms of vertical and horizontal stability in the short follow-up period of acute acromioclavicular joint (ACJ) dislocations fixed with an arthroscopically assisted coracoclavicular single bundle endobutton cerclage system. The secondary aim was to investigate the impact of postoperative recurrent instability on clinical outcomes in these populations.

METHODS

In this consecutive clinical trial, all patients who underwent surgery for acute AC joint dislocation between January 2017 and December 2021 were included. Two groups were formed according to the additional AC stabilisation technique (K-wire group, cerclage group). Clinical examination and bilateral radiologic analysis (Zanca stress view, Alexander view) were performed with a follow-up period of at least 12 months. Satisfaction, return to sports, active range of motion, global shoulder scores and specific shoulder scores including constant score, disabilities of the arm, shoulder and hand (DASH) score and ACJ instability score (ACJI) were evaluated. Complications, including recurrent instability, and revision rate were assessed.

RESULTS

Included were 59 patients (32 K-wire group, 27 cerclage group, 92% male, median follow-up 33 months). No significant differences were found in the clinical outcome parameters between the different techniques, except for the DASH value (superior in the K-wire group). Recurrent anteroposterior instability was radiographically detected in 27% of patients. No correlation was found between anteroposterior instability and clinical outcome parameters. There was no revision surgery due to chronic ACJ instability.

CONCLUSION

Horizontal ACJ stabilisation with temporary K-wire transfixation does not appear to be inferior to a FiberTape cerclage technique in acute ACJ dislocations stabilised in an arthroscopically assisted single bundle DogBone technique. Recurrent ACJ instability detected radiographically does not necessarily correlate with the functional outcome and can be well compensated.

LEVEL OF EVIDENCE

Level III.

Type III acromioclavicular dislocation: Mid term results after operative and non-operative treatment

INTRODUCTION

Controversy exists in the literature about the best treatment for type III acromioclavicular dislocations. The aim of this study is to compare functional results between surgical and conservative treatment in type III acromioclavicular joint dislocations.

MATERIAL AND METHOD

We retrospectively evaluated the records of 30 patients from our area with acute type III acromioclavicular dislocations that were treated from January 1st, 2016 to December 31st, 2020. Fifteen patients were treated surgically and 15 conservatively. Follow up mean time was 37.93 months in operative group and 35.73 months in non-operative group. Results obtained on the Constant score was the main variable analysed and results obtained on the Oxford score and the Visual Analogue Scale for pain were the secondary variables. Epidemiological variables were analysed, as well as range of mobility in injured shoulder and subjective and radiological variables (distance between the superior border of the acromion and the superior border of the clavicle's distal end and presence of osteoarthritis in the acromioclavicular joint).

RESULTS

Functional evaluation scores did not show differences between the two groups (Constant: operative 82/non-operative 86.38, p 0.412; Oxford: operative 42/non-operative 44.80, p 0.126) nor did Visual Analogue Scale (operative 1/non-operative 0.20, p 0.345). Subjective evaluation of the injured shoulder was excellent or good in 80% of the patients in both groups. Measurement of the distance between the superior border of the acromion and the superior border of the clavicle's distal end were significantly higher in non-operative group (operative 8.95/non-operative 14.21, p 0.008).

CONCLUSIONS

Although radiographic results were better in the surgical treatment group, functional evaluation scores did not show significant differences between the two groups. These results do not support the routine use of surgical treatment for grade III acromioclavicular dislocations.

Medial placement of trapezoid tunnel leads to higher reduction loss in acute acromioclavicular joint dislocation treated with anatomic coracoclavicular fixation

Aim

To analyze the association between clavicular tunnel positioning and postoperative reduction loss in patients with acute acromioclavicular (AC) joint dislocation treated with anatomic coracoclavicular (CC) fixation using double clavicular tunnels.

Methods

A retrospective review of patients with AC joint dislocation, treated with anatomic CC fixation using double clavicular tunnels, was conducted. Patients with pre-operative, immediate post-operative, and final follow-up Zanca-view X-rays were included. On each X-ray, the obtained measures included: distance from lateral border of clavicle to trapezoid and conoid tunnels, distance between tunnels, clavicle length, and CC distance of affected and un-affected sides. Loss of reduction was calculated as CC distance difference between immediate and final post-operative X-rays. Association between reduction loss and tunnel positioning was analyzed.

Results

Conoid, trapezoid and tunnel ratios were 24% ± 4, 15% ± 3, and 9% ± 2, respectively. Significant reduction loss was seen in 21(45.7%) patients. Significantly higher probabilities of reduction loss were associated with trapezoid tunnels placed medial to 24 mm (30.8% vs 65.0%, OR 4.2 (IC95%: 1.2-14.4), p: 0.024) or 15% of the clavicle length (32.1% vs 66.7%, OR 4.2 (IC 95%: 1.2-14.9), p: 0.025).

Conclusions

Trapezoid tunnels placed medial to 24 mm or 15% medial to clavicle length could lead to higher probabilities of significant reduction loss. These findings support the importance of clavicular tunnels' proper placement for decreasing significant reduction loss.

The ISAKOS subclassification of Rockwood type III AC joint dislocations in a stable type A and an unstable type B is not clinically relevant

PURPOSE

The treatment of Rockwood type III AC joint dislocations has been debated for decades. In 2014, the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Upper Extremity Committee suggested a subclassification of the injury into type A, considered stable and best treated nonsurgically, and type B, considered unstable and best treated surgically. Type B is defined by the presence of scapular dyskinesis and overriding of the clavicle to the acromion on a modified lateral radiograph. The objective of the study was to investigate if this subclassification is clinically relevant.

METHODS

This was a prospective cohort study. Inclusion criteria were patients aged 18-60 years with acute AC joint dislocation and a baseline Zanca radiograph with an increase in the CC distance of >25% compared to the uninjured side. All patients were treated nonsurgically with 3 months of home-based training and with the option of delayed surgical intervention. Patients were assessed at baseline and at follow-ups 6 weeks, 3 months, 6 months and 1 year after the injury. At the 6-week follow-up, patients were graded as stable and unstable according to the ISAKOS criteria. Outcomes were the Western Ontario Shoulder Instability Index (WOSI) and referral for surgery.

RESULTS

At 6 weeks of follow-up, 20 patients were classified as stable type A and 69 were classified as unstable type B. The ISAKOS subclassification was not clinically relevant, but patients graded as stable had statistically significantly better WOSI scores at 6 months compared to the unstable group (p = 0.03) but not at 3 months or 1 year. Nine patients (9.5%), all from the unstable group, were referred for surgery. No patients from the stable group underwent surgery (n.s).

CONCLUSION

The ISAKOS subclassification of Rockwood type III in a stable type A and an unstable type B is not clinically applicable.

LEVEL OF EVIDENCE

Level II.

Patient-reported, clinical and radiological factors associated with the result after non-surgical management of acute AC joint dislocation Rockwood type III and V

PURPOSE

The treatment of Rockwood type III and V acromioclavicular (AC) joint dislocations is controversial, and an individualized treatment algorithm is yet to be developed. The objective of this study was to investigate the association of demographical, clinical, patient-reported and radiological variables with the Western Ontario Shoulder Instability Index (WOSI) score and risk of surgery.

METHODS

Inclusion criteria for this prospective cohort study were patients aged 18-60 with an acute AC joint dislocation with >25% increase in the coracoclavicular distance on bilateral Zanca radiographs. Patients were treated non-surgically with 3 months of home-based training and the option of delayed surgical intervention. The outcomes were the WOSI score and surgery yes/no. Demographical, clinical, patient-reported (WOSI and Shoulder Pain and Disability Index [SPADI]) and radiological variables were collected at baseline and 6 weeks after the injury and investigated for association with the outcomes at 3 months, 6 months and 1 year.

RESULTS

Ninety-five patients with Rockwood type III/V AC joint dislocation were included. Pre-injury participation in overhead/collision sports was a risk factor for surgery with an odds ratio of 5 (p = 0.03). Reduced range of motion (ROM) at baseline was associated with reduced WOSI scores and increased risk of surgery. At 6 weeks, reduced ROM, increased SPADI and increased pain during cross-over were associated with the outcomes. Radiological measurements were not correlated with the result. At the 6 weeks follow-up, patients eventually requiring surgery could be detected with a sensitivity of 100% and a specificity of 94% based on a SPADI score of >30 and a ROM ≤ 140° in shoulder flexion or abduction.

CONCLUSION

ROM was the only variable consistently associated with both WOSI and risk of surgery. Six weeks after the injury, it was possible to detect patients in need of surgery based on ROM and SPADI with a sensitivity of 100% and a specificity of 94%.

LEVEL OF EVIDENCE

Level II.

[Translated article] Type III acromioclavicular dislocation: Mid term results after operative and non-operative treatment

INTRODUCTION

Controversy exists in the literature about the best treatment for type III acromioclavicular dislocations. The aim of this study is to compare functional results between surgical and conservative treatment in type III acromioclavicular joint dislocations.

MATERIAL AND METHOD

We retrospectively evaluated the records of 30 patients from our area with acute type III acromioclavicular dislocations that were treated from January 1st, 2016 to December 31st, 2020. Fifteen patients were treated surgically and 15 conservatively. Follow-up mean time was 37.93 months in operative group and 35.73 months in non-operative group. Results obtained on the Constant score was the main variable analysed and results obtained on the Oxford score and the Visual Analogue Scale for pain were the secondary variables. Epidemiological variables were analysed, as well as range of mobility in injured shoulder and subjective and radiological variables (distance between the superior border of the acromion and the superior border of the clavicle's distal end and presence of osteoarthritis in the acromioclavicular joint).

RESULTS

Functional evaluation scores did not show differences between the two groups (Constant: operative 82/non-operative 86.38, p 0.412; Oxford: operative 42/non-operative 44.80, p 0.126) nor did Visual Analogue Scale (operative 1/non-operative 0.20, p 0.345). Subjective evaluation of the injured shoulder was excellent or good in 80% of the patients in both groups. Measurement of the distance between the superior border of the acromion and the superior border of the clavicle's distal end were significantly higher in non-operative group (operative 8.95/non-operative 14.21, p 0.008).

CONCLUSIONS

Although radiographic results were better in the surgical treatment group, functional evaluation scores did not show significant differences between the two groups. These results do not support the routine use of surgical treatment for grade III acromioclavicular dislocations.

Double Fixation Technique for Acute Acromioclavicular Joint Dislocation Using the Two-Button Technique and Gracilis Autograft Reinforcement: A Case Report of an Elite Athlete Seeking a Rapid Return to Sports Activity

Acromioclavicular joint dislocation is a relatively common injury in the general population, especially in younger ages. Although acromioclavicular injuries are a well-studied topic, there are many controversies concerning not only the best way to treat them by operative or conservative methods but also determining the most effective fixation methods, providing better functional outcomes, faster rehabilitation protocols, fewer complications, and lower recurrence rates. In this case report, we present a case of type III acromioclavicular dislocation in a young athlete who was treated operatively using a double fixation technique, aiming to address these controversies and offer insights into the optimal management of such injuries.

Current trends in surgical treatment of the acromioclavicular joint injuries in 2023: a review of the literature

Background

This article examines the wide range of surgical reconstruction options available for acromioclavicular (AC) joint injuries. However, the lack of consensus regarding the most suitable surgical techniques is attributed to the high and variable failure rates observed with current approaches.

Methods

This article presents a comprehensive overview of the current surgical principles and techniques used by renowned experts in the field of AC shoulder injury management.

Results

It emphasizes the significance of addressing horizontal and rotational instability in AC injuries and highlights the impact of impaired scapular biomechanics.

Conclusion

By exploring these emerging concepts and strategies, the article aims to lay the foundation for future studies aimed at improving treatment outcomes and patient management.

What are our patients asking Google about acromioclavicular joint injuries?-frequently asked online questions and the quality of online resources

Background

Management of acromioclavicular (AC) joint injuries has been an ongoing source of debate, with over 150 variations of surgery described in the literature. Without a consensus on surgical technique, patients are seeking answers to common questions through internet resources. This study investigates the most common online patient questions pertaining to AC joint injuries and the quality of the websites providing information.

Hypothesis

1) Question topics will pertain to surgical indications, pain management, and success of surgery and 2) the quality and transparency of online information are largely heterogenous.

Methods

Three AC joint search queries were entered into the Google Web Search. Questions under the "People also ask" tab were expanded in order and 100 results for each query were included (300 total). Questions were categorized based on Rothwell's classification. Websites were categorized by source. Website quality was evaluated by the Journal of the American Medical Association (JAMA) Benchmark Criteria.

Results

Most questions fell into the Rothwell Fact category (48.0%). The most common question topics were surgical indications (28.0%), timeline of recovery (13.0%), and diagnosis/evaluation (12.0%). The least common question topics were anatomy/function (3.3%), evaluation of surgery (3.3%), injury comparison (1.0%), and cost (1.0%). The most common websites were medical practice (44.0%), academic (22.3%), and single surgeon personal (12.3%). The average JAMA score for all websites was 1.0 ± 1.3. Government websites had the highest JAMA score (4.0 ± 0.0) and constituted 45.8% of all websites with a score of 4/4. PubMed articles constituted 63.6% (7/11) of government website. Comparatively, medical practice websites had the lowest JAMA score (0.3 ± 0.7, range [0-3]).

Conclusion

Online patient AC joint injury questions pertain to surgical indications, timeline of recovery, and diagnosis/evaluation. Government websites and PubMed articles provide the highest-quality sources of reliable, up-to-date information but constitute the smallest proportion of resources. In contrast, medical practice represents the most visited websites, however, recorded the lowest quality score. Physicians should utilize this information to answer frequently asked questions, guide patient expectations, and help provide and identify reliable online resources.

Editorial Commentary: Acromioclavicular Joint Reconstruction With Double-Bundle Constructs Provides Improved Maintenance of Reduction but Comparable Clinical Outcomes Versus Single-Bundle Constructs

Treatment of acute acromioclavicular (AC) joint separations is dependent on a variety of factors, including severity, acuity, patient demographics, activity level, and surgeon preferences. For more severe or unstable separations (Rockwood types IIIB, IV, V, and VI), surgical intervention is typically recommended. Over 160 surgical techniques have been described, but none have emerged as a gold standard. Arthroscopic-assisted or all-arthroscopic fixation of the coracoclavicular ligaments with suture buttons has become increasingly popular due to lower complication rates compared with more rigid fixation. Configurations include single-bundle (SB) constructs and double-bundle (DB) configurations that more anatomically reconstruct the conoid and trapezoid ligaments but with longer operative times. Clinical studies with short-term follow-up have demonstrated improved maintenance of fixation for DB compared with SB constructs but no significant differences in clinical outcomes. In our experience, SB suture button-only constructs lead to unacceptable failures due to loss of reduction. We recommend either a single suture button construct augmented with allograft or DB suture button constructs for the treatment of acute AC joint separations.

Return to Play After Surgical Treatment for Acromioclavicular Joint Dislocation: A Systematic Review

BACKGROUND

Acromioclavicular (AC) joint dislocation is a common clinical problem among young and athletic populations. Surgical management is widely used for high-grade dislocations (Rockwood III-VI) and in high-demand athletes at high risk of recurrence.

PURPOSE

To systematically review the evidence in the literature to ascertain the rate and timing of return to play (RTP) and the availability of specific criteria for safe RTP after surgical treatment for AC joint dislocation.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic literature search based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was conducted in the PubMed database. Clinical studies were eligible for inclusion if they reported on RTP after surgical treatment for AC joint dislocation. Statistical analysis was performed with SPSS.

RESULTS

We found 120 studies including 4327 cases meeting our inclusion criteria. The majority of patients were male (80.2%), with a mean age of 37.2 years (range, 15-85) and a mean follow-up of 34.5 months. Most were recreational athletes (79%), and the most common sport was cycling. The overall rate of RTP was 91.5%, with 85.6% returning to the same level of play. Among collision athletes, the rate of RTP was 97.3%, with 97.2% returning to the same level of play. In overhead athletes, the rate of RTP was 97.1%, with 79.2% returning to the same level of play. The mean time to RTP was 5.7 months (range, 1.5-15). Specific RTP criteria were reported in the majority of the studies (83.3%); time to return to play was the most commonly reported item (83.3%). Type III Rockwood injuries had the highest RTP rate at 98.7% and the earliest RTP at 4.9 months. Among the different surgical techniques, Kirschner wire fixation had the highest rate of RTP at 98.5%, while isolated graft reconstruction had the earliest RTP at 3.6 months.

CONCLUSION

The overall rate of RTP was reportedly high after surgical treatment for AC joint dislocation, with the majority of patients returning to their preinjury levels of sport. There is a lack of consensus in the literature for what constitutes a safe RTP, with further focus on this topic required in future studies.

Functional reconstruction of chronic acromioclavicular joint separation using a double suture technique combined with semitendinosus autograft

PURPOSE

We present the functional and clinical results of a combined surgical technique that functionally restores chronic Acromioclavicular Joint Instability (AJI). The method combines a double-looped suture fixation augmented with a semitendinosus autograft.

METHODS

Between 2017 and 2021, 15 patients were treated using the surgical technique. All patients suffered an Acromioclavicular Joint Separation that remained untreated for at least 6 (6-16) weeks after the initial injury. Four Ethibond sutures were passed below the coracoid process and through a 4.5 drill hole in the clavicle. The sutures provided adequate horizontal and vertical reduction and stabilization of the clavicle. A semitendinosus autograft was passed below the coracoid process and looped around the clavicle. The remaining graft limbs were used to reconstruct the acromioclavicular capsule. Patients were radiologically evaluated with bilateral anteroposterior (AP), Zanca, and Alexander views. The clinical evaluation was based on the Acromioclavicular Joint Instability Score and the Constant-Murley Score.

RESULTS

The mean follow-up period was 31.2 months (17-61). The mean last ACJIS and CMS scores were 96 (90-100) and 97.67 (87-100), respectively. Reduction of the clavicle was radiologically confirmed in all cases throughout the follow-up period. AC arthritis was reported in 1 case without associated clinical symptoms. No significant complications were reported, and all patients returned to the pre-injury activity level.

CONCLUSION

The presented functional reconstruction of the AC joint disruption in chronic cases is an effective and secure method with low complication rates and good clinical results.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

High Vertical and Horizontal Stability at Short-Term Follow-Up After an All-Endoscopic Double Cerclage Endobutton Technique for Acute Acromioclavicular Joint Separations

PURPOSE

To evaluate the clinical and radiological outcomes in the treatment of acute acromioclavicular (AC) joint separations using an all-endoscopic double cerclage endobutton technique compared with an arthroscopic-assisted single-bundle endobutton technique and to analyze the complication, failure, and revision rates of both procedures.

METHODS

All patients with acute Rockwood type IIIB and V AC joint separations who were operated on using an all-endoscopic double cerclage technique (2019-2022) or an arthroscopic-assisted single-bundle technique (2017-2019) were included. The follow-up period was at least 12 months. Clinical and radiographic assessment was performed at follow-up. Complications, failures, and revisions were also investigated.

RESULTS

Twenty-eight patients (14 double cerclage group, 14 single-bundle group, all male) with an average age of 37 years (interquartile range [IQR], 15) were available for follow-up after 45 months (IQR, 38). The median time between trauma and surgery was 7 days (IQR, 8). Very good clinical results without significant differences were observed in both groups (Constant score, 94 [IQR, 12] vs 95 [IQR, 15], P = .427, AC joint instability score, 95 [IQR, 11] vs 87 [IQR, 22], P = .210). All patients returned to sport, with an average sports level of 95% compared with preoperative status. The single-bundle group showed significantly increased anteroposterior instability (6 vs 0, P = .006). A total of 5 complications occurred (2 vs 3), leading to 1 revision surgery in each group.

CONCLUSIONS

Excellent clinical results and high vertical and horizontal stability can be achieved with the all-endoscopic double cerclage technique. Horizontal instability occurred significantly more frequently with the single-bundle technique. The prolonged operation time in the double cerclage group had no negative impact on postoperative outcomes, including complication and failure rates, and a learning curve to reduce this prolonged operative time should be considered.

LEVEL OF EVIDENCE

Level III, retrospective comparative clinical series.

Double figure of eight technique using fiber tape for acute high-grade acromioclavicular joint dislocations - Reconstruction technique

Acromioclavicular (AC) joint dislocations are not uncommon injuries. High-grade dislocations can be managed by arthroscopic as well as open techniques, but the most important thing is to address both vertical and horizontal stability. The purpose of this study is to evaluate the functional outcome of a cost effective double figure of eight technique of stabilizing both coracoclavicular and acromioclavicular ligaments in acute high-grade disruption (Type IIIB -VI) using fibre tape. This study was performed at our tertiary care centre from 2017 to 2020 after appropriate IRB approval and patient consent. Out of 134 cases, 23 high-grade AC joint disruptions treated with our technique were included in the study. Demographic data analysis, pre-op and post-op Constant score and UCLA scoring were done to assess the functional outcome; Coracoclavicular distance (CCD) and CCD ratio were used to assess the radiological outcome. Significant improvement in Constant and UCLA shoulder scores were observed from pre-op to final follow up. With respect to the radiological outcome, all cases had a significant improvement in CCD and CCD ratio from baseline to final follow-up. To conclude, our double figure of eight technique is more anatomical, addresses both vertical and horizontal stability, easily reproducible, cost-effective and safe technique.

Current Concepts in Management of Acromioclavicular Joint Injury

Background: The management of acromioclavicular joint injuries requires a thorough understanding of the anatomy and biomechanics of the joint, as well as knowledge of the pertinent physical exam findings and classification to determine an appropriate treatment approach, whether operative or nonoperative. In this article, we present a narrative review of the current state of understanding surrounding these issues. Although there are a large number of options for operative intervention, we additionally present our experience with anatomic coracoclavicular ligament reconstruction (ACCR) with imbrication of the deltoid fascia. Methods: A retrospective review of prospectively collected data on a total of 45 patients who had undergone ACCR between 2003 and 2016 were collected. Results: We found that improvements were seen in American Shoulder and Elbow Surgeons Score (ASES) (53 ± 19 to 81 ± 23), Simple Shoulder Test (SST) (6 ± 3 to 12 ± 13), Constant-Murley (CM) (60 ± 18 to 92 ± 8), and Rowe (67 ± 14 to 89 ± 11) and the mean post-operative SANE score was 86 ± 17. Conclusions: ACCR has the advantage of addressing both horizontal and vertical stability with good outcomes.

Acromioclavicular joint separation: Controversies and treatment algorithm

In this article, we present an uptodate outline of acromioclavicular (AC) joint separation. A clear understanding of acromioclavicular joint injury in terms of the mechanism of injury, clinical picture, diagnostic imaging, and most updated surgical techniques used for the treatment can provide the best care for those patients. This article describes updated treatment strategies for AC separation, including type III AC separation which is known most controversial. Finally, we present a proposed treatment algorithm that can aid in the treatment of AC separation from the most updated evidence.

Long-Term Functional Outcomes and Athletic Ability in Shoulder Sports After Anatomic Coracoclavicular Ligament Reconstruction for Chronic Type 3 and 5 Acromioclavicular Joint Injuries

Background

Promising short- and midterm outcomes have been seen after anatomic coracoclavicular ligament reconstruction (ACCR) for chronic acromioclavicular joint (ACJ) injuries.

Purpose/Hypothesis

To evaluate long-term outcomes and shoulder-related athletic ability in patients after ACCR for chronic type 3 and 5 ACJ injuries. It was hypothesized that these patients would maintain significant functional improvement and sufficient shoulder-sport ability at a long-term follow-up.

Study Design

Case series; Level of evidence, 4.

Methods

Included were 19 patients (mean age, 45.9 ± 11.2 years) who underwent ACCR for type 3 or 5 ACJ injuries between January 2003 and August 2014. Functional outcome measures included the American Shoulder and Elbow Surgeons (ASES), Rowe, Constant-Murley, Simple Shoulder Test (SST), and Single Assessment Numeric Evaluation (SANE) scores as well as the visual analog scale (VAS) for pain, which were collected preoperatively and at the final follow-up. Postoperative shoulder-dependent athletic ability was assessed using the Athletic Shoulder Outcome Scoring System (ASOSS). Shoulder activity level was evaluated using the Shoulder Activity Scale (SAS), while the Subjective Patient Outcome for Return to Sports (SPORTS) score was collected to assess the patients' ability to return to their preinjury sporting activity.

Results

The mean follow-up time was 10.1 ± 3.8 years (range, 6.1-18.8 years). Patients achieved significant pre- to postoperative improvements on the ASES (from 54.2 ± 22.6 to 83.5 ± 23.1), Rowe (from 66.6 ± 18.1 to 85.3 ± 19), Constant-Murley (from 64.6 ± 20.9 to 80.2 ± 22.7), SST (from 7.2 ± 3.4 to 10.5 ± 2.7), SANE (from 30.1 ± 23.2 to 83.6 ± 26.3), and VAS pain scores (from 4.7 ± 2.7 to 1.8 ± 2.8) (P < .001 for all), with no significant differences between type 3 and 5 injuries. At the final follow-up, patients achieved an ASOSS of 80.6 ± 32, SAS level of 11.6 ± 5.1, and SPORTS score of 7.3 ± 4.1, with no significant differences between type 3 and 5 injuries. Four patients (21.1%) had postoperative complications.

Conclusion

Patients undergoing ACCR using free tendon allografts for chronic type 3 and 5 ACJ injuries maintained significant improvements in functional outcomes at the long-term follow-up and achieved favorable postoperative shoulder-sport ability, activity, and return to preinjury sports participation.

Effect of cigarette smoking on the maintenance of reduction after treatment of acute acromioclavicular joint dislocation with hook plate fixation

BACKGROUND

The purpose of this study was to determine the association between smoking and clinical outcomes of hook plate fixation for acute acromioclavicular (AC) joint injuries.

METHODS

This study retrospectively investigated 82 patients who underwent hook plate fixation for acute AC joint dislocation between March 2014 to June 2022. The patients were grouped by smoking status, with 49 in group N (nonsmokers) and 33 in group S (smokers). Functional scores and active range of motion were compared among the groups at the 1-year follow-up. Coracoclavicular distance (CCD) was measured, and difference with the uninjured side was compared at initial injury and 6 months after implant removal.

RESULTS

No significant differences were observed between the two groups in demographic factors such as age and sex, as well as parameters related to initial injury status, which included time from injury to surgery, the preoperative CCD difference value, and the Rockwood classification. However, the postoperative CCD difference was significantly higher in group S (3.1±2.6 mm) compared to group N (1.7±2.4 mm). Multivariate regression analysis indicated that smoking and the preoperative CCD difference independently contributed to an increase in the postoperative CCD difference. Despite the radiographic differences, the postoperative clinical outcome scores and active range of motion measurements were comparable between the groups.

CONCLUSIONS

Smoking had a detrimental impact on ligament healing after hook plate fixation for acute AC joint dislocations. This finding emphasizes the importance of smoking cessation to optimize reduction maintenance after AC joint injury. Level of evidence: III.

Editorial Commentary: Tunnel Widening and Loss of Reduction May Be Inevitable After Acromioclavicular Stabilization With Cortical Suspensory Devices Whether Inset (Top Hats) or Onlay (Buttons)

Despite widely varying techniques, coracoclavicular (CC) stabilization after traumatic, unstable acromioclavicular (AC) joint dislocations shows notable rates of perioperative complications, radiographic loosening, and, ultimately, loss of anatomic reduction. Loss of reduction can occur in upward of 40% of cases after CC repair or reconstruction. Complications and unplanned reoperations can approach 30% and 1.2% to 5.4%, respectively. While we posit that AC joint congruity confers greater shoulder function, anatomic reduction does not always correlate with patient satisfaction or favorable outcomes, which is estimated in up to 88% of surgically treated cases. AC joint repair or reconstruction often uses cortical suspensory button devices to maintain reduction until sufficient soft tissue healing of the CC and AC ligaments. Over time, the so-called windshield wiper phenomenon of the suture-button construct may lead to tunnel osteolysis and, in severe cases, secondary fracture of the coracoid or clavicle. Current efforts to characterize the extent of tunnel widening and ascertain its implications for radiographic outcomes are critical. Whether using inset, low-profile top hat devices or onlay buttons with adjustable loop fixation, loss of AC joint congruity remains unacceptably high. We should strive to more consistently trade a "bump for a scar," not a bump and a scar!

Clavicular Tunnel Widening After Acromioclavicular Stabilization Shows Implant-Dependent Correlation With Postoperative Loss of Reduction

PURPOSE

To radiographically describe, quantify, and compare clavicular tunnel widening (cTW) of 2 different types of stabilization devices and investigate a possible correlation between cTW and loss of reduction.

METHODS

In a retrospective analysis of single-center registry data, we compared patients who were treated for an acute AC dislocation (Rockwood types III to V) with either the AC Dog Bone (DB) or low-profile AC (LP) repair systems. On 6-week and 6-month postoperative radiographs, we measured clavicle height and tunnel diameter. We calculated the button/clavicle filling (B/C) ratio to quantify how much of the clavicular tunnel height is covered by the low-profile inlet. The association between B/C ratio and the extent of cTW was defined, and we also compared cTW between treatment groups. Reduction of the AC joint was graded as either stable, partially dislocated or dislocated depending on the AC ratio. A 2-sample t-test was used for comparing cTW progression between the 2 groups. For continuous variables between more than 2 groups, the Kruskal-Wallis test was used.

RESULTS

Of 65 eligible patients, there were 37 and 28 included in the DB and LP groups, respectively. Overall, cTW was conically shaped with transclavicular widening noted in the DB group and cTW developing strictly inferior to the button in the LP group. For both implants, mean maximal cTW was 7.1 mm and located at the inferior cortex; the B/C ratio was not associated with increased inferior cTW (r = -0.23, P = .248). Only LP patients with complete loss of reduction had significantly increased cTW (P = .049).

CONCLUSIONS

Conical-shaped cTW is a common implant-independent phenomenon after AC stabilization using suture-button devices. It occurs only at the suture-bone interface and is less excessive for the LP implant. There is an association between increased cTW and loss of reduction specific to the LP implant only.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Rockwood type III is the most common type of acromioclavicular joint dislocation: A prospective cohort study investigating the incidence and epidemiology of acute acromioclavicular joint dislocations in an urban population

Introduction

Acromioclavicular (AC) joint dislocations are common, but basic epidemiological features and sub-classification are not well investigated. The aim of the study was to investigate the incidence and epidemiology of acute AC joint dislocations in the capital region of Denmark.

Methods

All patients with acute AC joint dislocation admitted to the emergency departments at 3 University Hospitals serving a population of 549,225 residents were prospectively registered from January to December 2019. Patients with trauma to the shoulder, pain from the AC joint and increased coracoclavicular distance on radiographs were included and classified according to Rockwood's classification. Data on age, sex and mechanism of injury were registered.

Results

A total of 106 patients, male:female ratio 8.6:1, were included. Rockwood type III was most common accounting for 59/106(55.7%) of the injuries. The incidence was 19.3 per 100,000 person-years at risk (PYRS). The age distribution was bimodal peaking at the ages of 20-24 and 55-59 years. The most common mechanism of injury was sports, 80/106, with cycling accounting for 51/106.

Discussion/Conclusion

Rockwood type III was the most common type of AC joint dislocation constituting 55.7% of the injuries. The incidence was 19.3 per 100,000 PYRS. Young and middle-aged males were at highest risk and most injuries occurred during sports.

Acromioclavicular joint Stabilization: Our experience with the lockdown technique

Background

Acromioclavicular joint (AC joint) disruption is a common injury with considerable variation with regards to surgical management. The Lockdown™ procedure (previously known as Surgilig™), Modified Weaver-Dunn procedure, Arthroscopic AC joint stabilization and Ligament Augmentation and Reconstruction system (LARS) procedure have all been described for treatment of this injury with varying outcomes.

Purpose

To measure the functional and radiological outcomes following all cases of AC joint reconstruction using the Lockdown™ technique over the last 10 years at Medway Maritime Hospital.

Methods

Data on a total of 53 patients who underwent AC joint reconstruction between 2012 and 2021 were collected. Electronic records were used to extract data regarding patient characteristics, surgery details, and duration of follow-up. Telephonic interviews of patients were conducted to collect data on hand dominance, surgical complications, and responses to Oxford shoulder score (OSS) and QuickDASH score questionnaires. Hospital PACS data were reviewed to record preoperative injury severity and postoperative acromioclavicular joint reduction.

Results

Results for 42 patients were available and analysed as 10 could not be contacted and 1 patient sadly passed away. Of the patients reviewed, 92.9% were males with a mean age of 42.2 years (Range 16-67 years) and mean follow up of 68 months (12-119.1 months). The injury involved the dominant arm in 59.5%cases. Majority of the cases were Rockwood type V injuries (71.43%) while the rest were either type III(19.05%) or type IV(9.52%).The mean preoperative OSS was 21.3/48 which improved to 44.3/48 in the postoperative period. Similarly, the mean QuickDASH score was 50.6 preoperatively, that improved to 9.1 postoperatively.The most common patient reported complication was prominent metalwork seen in 5 cases (11.6%) followed by stiffness seen in 3 cases (7%) and superficial infection seen in 1 case (2.3%). The AC joint remained reduced radiologically in 81% of cases, while a resubluxation between 50 and 100% was seen in the rest of the cases. Patients with radiological resubluxation did not report this as a complication in 87.5% of the cases. Overall, 38 patients reported their outcome as excellent, 2 patients rated it good while 1 patient reported it as fair and 1 as poor.

Conclusion

The Lockdown™ technique for stabilization of AC joint has excellent or good patient satisfaction in 95.2% of cases in long term follow up of more than 5.7 years. Prominent metalwork and stiffness are the commonest clinical complications. Radiological resubluxation can be seen in a fifth of the cases but does not directly lead to patient dissatisfaction.

Level of evidence

Level IV Retrospective case series.

Arthroscopic Repair and Reconstruction of Coracoclavicular Ligament

Acromioclavicular joint separations are common shoulder injuries that require prompt recognition, diagnosis, and treatment. Deciding on a treatment algorithm relies on a detailed knowledge of anatomy and a thorough understanding of the specific functional demands of the patient in question. When a repair or reconstruction is indicated, arthroscopic assistance can be a helpful tool to ensure a safe, anatomic reconstruction that minimizes morbidity and maximizes the potential return to high-level function.

Open Anatomic Coracoclavicular Ligament Reconstruction for Acromioclavicular Joint Injuries

Open reconstruction of the coracoclavicular (CC) and acromioclavicular (AC) ligaments results in excellent reduction of severely displaced AC dislocations, most commonly Grades III and V. Anatomic CC reconstruction through clavicular bone tunnels can prevent vertical instability, whereas the addition of an acromial limb of the graft can increase horizontal stability. Autograft tendon is preferred in the young athletic group of collision sports participants, although allograft has had acceptable results. Accessory fixation may be placed to protect the graft during healing, or for severe instability, especially for athletes involved in contact sports.

Management of Acromioclavicular Joint Injuries: A Historic Account

There has been a rapid evolution in best practice management of acromioclavicular (AC) joint injuries. AP, Zanca, scapular Y, and dynamic axillary radiographic views provide optimal visualization of the joint and may assess for the presence of horizontal AC instability. Severity of AC joint pathology is classified according to the 6-tier Rockwood scoring system. Over 160 surgical techniques have been described for AC joint repair and reconstruction in the last decade; as a result, determining the optimal treatment algorithm has become increasingly challenging secondary to the lack of consistently excellent clinical outcomes.

Surgical Pearls and Pitfalls for Anatomic Acromioclavicular/Coracoclavicular Ligament Reconstruction

Injuries to the acromioclavicular (AC) joint are common shoulder injuries in contact/collision athletes. There are a number of different surgical options that can be used to treat these injuries. The majority of these injuries can be treated nonoperatively with an early return to play for type I and II injuries. Surgical intervention and AC/CC (coracoclavicular) ligament reconstruction have excellent postoperative outcomes if complications can be avoided. This review will focus on the pearls and pitfalls for anatomic AC and CC ligament reconstruction for high-grade AC joint injuries.

Assessment of Coracoclavicular Ligament Healing on MRI After Arthroscopic TightRope Fixation for Acute Acromioclavicular Joint Dislocation

Background

Arthroscopic-assisted fixation of acute high-grade acromioclavicular (AC) joint dislocation has gained popularity in the last decade. Coracoclavicular (CC) fixation using the TightRope device is a less invasive technique.

Purpose

To investigate CC ligament healing and functional outcomes after arthroscopic fixation using the TightRope device for acute AC joint disruption.

Study Design

Case series; Level of evidence, 4.

Methods

The study retrospectively analyzed the data of patients admitted for arthroscopic surgical treatment of acute AC joint injury using a single TightRope device. The data collection commenced in October 2021. The Constant-Murley (CM) score and University of California, Los Angeles (UCLA) shoulder score were used for functional evaluation. The CC distance (CCD) was measured on plain radiographs, whereas healing of the CC ligament was evaluated on magnetic resonance imaging (MRI). Statistical analyses were conducted with the Mann-Whitney U test, independent t test, or paired t test, as appropriate.

Results

The analysis included 33 patients with a mean age of 37.7 years (range, 24-49 years) and a minimum follow-up of 24 months. Significant preoperative to postoperative increases were noted in both the CM and UCLA scores (from 34.1 ± 7.6 to 93.3 ± 3.6 and from 8.7 ± 2.1 to 32.9 ± 1.7, respectively; P < .0001 for both). The CCD decreased from 21.8 ± 3.02 mm preoperatively to 10.6 ± 1.2 mm postoperatively (P < .0001). All patients displayed CC ligament healing on MRI. Two patients with superficial infection and 1 case of partial reduction loss were confirmed at the end of this study.

Conclusion

The arthroscopic TightRope technique was found to be a reliable and less invasive method of fixation for acute AC joint disruptions. The CC ligament healed adequately based on MRI evaluation, and the patients regained their preinjury activities, with favorable functional outcomes and minor comorbidities.

Acromioclavicular Joint Lesions in Adolescents-A Systematic Review and Treatment Guidelines

True acromioclavicular joint (ACJ) injuries are rare in children and adolescents due to the strength of ligaments in this age group. However, a standardized management guideline for these injuries is currently lacking in the literature. This systematic review aims to provide an organized overview of associated injuries and propose a management algorithm for pediatric ACJ injuries. Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic review was conducted. Two independent observers searched PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and Scopus databases for ACJ injuries in children and adolescents. The extracted data were analyzed (due to the limited number of publications and inhomogeneity of data, no formal statistical analysis was conducted), and cases were categorized based on injury frequency and pattern, leading to the formulation of a treatment algorithm. The risk of bias was assessed using the Joanna Briggs Institute (JBI) critical appraisal checklist. A total of 77 articles were identified, and 16 articles (4 case series and 12 case reports) met the inclusion criteria. This study included 37 cases in 36 patients (32 males, 4 females) with a mean age of 13 years (9-17 years). Six injury categories were described. Surgical management was performed in 27 ACJ injuries (25 open, 2 arthroscopic). Various surgical implants were used including K wires, polydioxanone sutures (PDS), screws, hook plates, suture anchors, and suture button devices. Most cases achieved good to excellent outcomes, except for one case of voluntary atraumatic dislocation of the ACJ. This systematic review provides the first comprehensive analysis of ACJ injury management in adolescents with open physis. It categorizes injury patterns and presents a treatment algorithm to enhance the understanding of these injuries. The review's findings contribute valuable insights for clinicians dealing with pediatric ACJ injuries.

Prospective Multicenter Randomized Controlled Trial of Surgical Versus Nonsurgical Treatment for Acute Rockwood Type 3 Acromioclavicular Injury

Background

Evidence for the superiority of surgical versus nonsurgical treatment of Rockwood type 3 acromioclavicular joint (ACJ) dislocation is still lacking.

Hypothesis

It was hypothesized that surgical treatment will outperform nonsurgical treatment.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

A prospective randomized trial involving 4 study centers was performed from January 1, 2011, to March 31, 2016. A total of 85 patients with acute Rockwood type 3 ACJ dislocations were allocated randomly to receive either nonsurgical or surgical treatment. A total of 70 patients were treated as allocated, and 8 patients made an early crossover from nonsurgical to surgical treatment, leaving 47 patients treated surgically and 31 patients nonsurgically. All patients were followed up longitudinally, including clinical evaluation using the Constant score and standardized radiographic evaluation, with final follow-up after 2 years.

Results

At no follow-up time point was there a significant difference in Constant score between the surgically and nonsurgically treated patients. Radiographic analysis showed not only an inferior coracoclavicular distance at all follow-up points for surgical treatment but also a higher incidence of posttraumatic osteoarthritis and heterotopic ossifications, without any negative clinical correlation. With regard to complications, 1 patient (3%) in the nonsurgical group underwent secondary surgical ACJ stabilization. The revision rate after surgical treatment was 17% (P < .001). Neither primary horizontal instability nor younger age were associated with inferior clinical outcomes after nonsurgical treatment.

Conclusion

Surgical treatment of ACJ Rockwood type 3 injuries did not lead to superior functional outcomes. Neither younger age nor horizontal instability were associated with inferior outcomes after nonsurgical treatment. Surgical treatment led to a slower recovery and to higher complication and revision rates.

Registration

ISRCTN registry (study ID: ISRCTN92265154).

Comparison of Effectiveness and Safety in Treating Acute Acromioclavicular Joint Dislocation with Five Different Surgical Procedures: A Systematic Review and Network Meta-Analysis

This network meta-analysis aims to evaluate the comparative effectiveness and safety of suture anchors (SA), tendon grafts (TG), hook plates (HP), Tight-Rope (TR), and EndoButton (EB) in the treatment of acute acromioclavicular joint (ACJ) dislocation. The Embase, PubMed, and Web of Science databases were searched from their inception date to June 3, 2022. Studies included all eligible randomized controlled trials (RCTs) and cohort studies with the comparison of five different fixation systems among SA, TG, HP, TR, and EB were identified. All studies were reviewed, performed data extraction, and assessed the risk of bias independently by two reviewers. The primary outcomes are Constant-Murley score (CMS) improvement for assessing clinical efficacy, and complications. The second outcomes are visual analog scale (VAS) for assessing pain relief and the coracoclavicular distance (CCD) for assessing postoperative joint reduction. Version 2 of the revised Cochrane risk of bias tool for randomized trials (RoB 2) and the risk of bias in nonrandomized studies of interventions (ROBINS-I) were used to assess the RCTs and non-randomized trials, respectively. The continuous outcomes were presented as mean differences (MD), and risk ratios (OR) were used for dichotomous outcomes, both with 95% confidence intervals (CI). Surface under the cumulative ranking curves (SUCRA) results were calculated to offer a ranking of each intervention. We identified 31 eligible trials, including 1687 patients in total. HP showed less CMS improvement than TR and EB in both the Network Meta-analysis (NMA) and pairwise meta-analysis. HP also showed less CMS improvement than SA in NMA. For pain relief, HP performed worse than TR both in pairwise meta-analysis and NMA. No significant differences were found for the measured value of CCD. Both TR and EB showed a lower incidence of complications than HP in pairwise meta-analysis. The rank of SUCRA for CMS improvement was as follows: SA, TR, EB, TG, and HP; for pain relief: TR, EB, TG, SA, and HP; for CCD: HP, TR, SA, EB, and TG. For complications, HP showed the highest rank, followed by TG, EB, TR, and SA. SA shows better clinical effectiveness and reliable safety in the treatment of acute ACJ dislocation. Although HP is the most widely used surgical option currently, it should be carefully taken into consideration for its high incidence of complications.

Anatomical acromioclavicular joint stabilization with chemically sterilized tendon allografts: A retrospective study

Background

The purpose of this retrospective study was to analyze whether chemically sterilized tendon allografts perform as well as other non-sterilized allografts and autografts as described in the literature for anatomical acromioclavicular joint stabilization for the treatment of Rockwood III-V. Allografts are still described as a factor for higher re-rupture rates.

Methods

Retrospective data were collected from 21 acromioclavicular joint stabilizations performed by a single surgeon and performed between 2011 and 2014 using sterilized semitendinosus allografts. The primary endpoints were re-rupture and complication rates. Secondary endpoints were AC-joint stability, pain level, return to work and sport and the range of motion.

Results

No re-ruptures occurred during the mean follow-up time of 33 months. Zero complications occurred directly after surgery, but three complications later than three weeks after surgery. All cases resolved without further surgery. After surgery, stability significantly improved for all patients. Post-surgery, 19 patients had stable acromioclavicular joints and only two patients showed minor instabilities. Range of motion returned to the range of the healthy shoulders for all patients.

Conclusion

Chemically sterilized semitendinosus allograft use for anatomic AC-joint stabilization is equivalent to the use of other allografts or autografts and required no hardware removal. No donor age or graft size dependence was observed, due to zero re-ruptures.

Minimally invasive reconstruction of acute acromioclavicular joint injuries using the TwinBridge button system

INTRODUCTION

Acute acromioclavicular joint (ACJ) injuries are among the most common shoulder injuries in active young adults. The most frequently used surgical treatments include the hook plate implantation and arthroscopic treatment using flip-button systems. The aim of this study was to evaluate the results of treating acute ACJ injuries using a new minimally invasive implant based on a flip-button system.

MATERIAL AND METHODS

From January 2016 to October 2019, a total of 20 patients with acute ACJ injuries (1 × Type III, 3 × Type IV, 16 × Type V) underwent surgery using the Twinbridge implant (Smith & Nephew). It is a prefabricated construct consisting of two Endobuttons connected with an UltraTape. One button is placed under the coracoid using a special aiming device and two buttons are placed on the clavicle. Preoperatively, 1 day postoperatively, 3 months and at least 1 year postoperatively, patients were clinically examined and bilateral stress view and axial radiographs were obtained. At final follow-up, the simple shoulder test (SST), Taft score, Constant score, and ACJ instability (ACJI) score were recorded and a side-to-side ratio of the coracoclavicular (CC) distance was calculated.

RESULTS

All 20 patients were contacted at final follow-up at a mean of 28 (min. 13, max 50) months. Six patients were not willing to come for a clinical and radiographic examination and were contacted via telephone. All six patients were free of complaints. Another two patients free of complaints refused radiographs at final follow-up. The patients presented a mean SST of 99.6% (20 patients, min. 91.7, max. 100), Taft score of 11.6/12 points (12 patients, min. 10, max. 12), ACJI of 85.5/90 points (12 patients, min. 78, max. 90), and a Constant score of 97.1 (14 patients, min. 81.0, max. 100) for the affected shoulder. Preoperative stress view images revealed a mean side-to-side difference of the CC distance with a ratio of 1:2.34 (min. 1:1.80, max. 1:3.33). At final follow-up, CC distance was calculated with a mean ratio of 1:1.12 (min. 1.1, max. 1:1.38). Axial images showed a proper position in all cases. A "perfect" radiological result was achieved in six patients (50%) with a side-to-side CC distance of less than 10% (ratio 1:1.1 or less). A Rockwood type II result was achieved in five patients (42%) with a distance of 10 to 25% (ratio 1.11-1.25). One (8%) presented with a Rockwood type III result with a difference of more than 25% (ratio 1:1.38) and was considered a radiological failure.

CONCLUSIONS

When used correctly, the Twinbridge implant offers good-to-excellent clinical and radiographic results using a minimally invasive surgical technique. Complication rate is comparable to other button-systems.

Iatrogenic instability of the acromioclavicular joint leads to ongoing impairment of shoulder function even following secondary surgical stabilization

PURPOSE

Iatrogenic instability of the acromioclavicular joint (ACJ) following distal clavicle excision (DCE) represents an infrequent pathology. Revision surgery to restore ACJ stability and alleviate concomitant pain is challenging due to altered anatomic relationships. The purpose of this study was to evaluate the used salvage techniques and postoperative functional and radiological outcomes in retrospectively identify patients with a painful ACJ following DCE. We hypothesized that iatrogenic instability leads to ongoing impairment of shoulder function despite secondary surgical stabilization.

METHODS

9 patients with a painful ACJ after DCE (6 men, 3 women, 43.3 ± 9.4 years) were followed up at a minimum of 36 months after revision surgery. Besides range of motion (ROM), strength and function were evaluated with validated evaluation tools including the Constant score and the DASH score (Disability of the Arm, Shoulder and Hand questionnaire), specific AC Score (SACS), Nottingham Clavicle Score (NCS), Taft score and Acromioclavicular Joint Instability Score (AJI). Additionally, postoperative X-rays were compared to the unaffected side, measuring the coracoclavicular (CC) and acromioclavicular (AC) distance.

RESULTS

At follow-up survey (55.8 ± 18.8 months) all patients but one demonstrated clinical ACJ stability after arthroscopically assisted anatomical ACJ reconstruction with an autologous hamstring graft. Reconstruction techniques were dependent on the direction of instability. The functional results demonstrated moderate shoulder and ACJ scores with a Constant Score of 77.3 ± 15.4, DASH-score of 51.2 ± 23.4, SACS 32.6 ± 23.8, NCS 77.8 ± 14.2, AJI 75 ± 14.7 points and Taft Score 7.6 ± 3.4 points. All patients stated they would undergo the revision surgery again. Mean postoperative CC-distance (8.3 ± 2.8 mm) did not differ significantly from the contralateral side (8.5 ± 1.6 mm) (p > 0,05). However, the mean AC distance was significantly greater with 16.5 ± 5.8 mm compared to the contralateral side (3.5 ± 1.9 mm) (p = 0.012).

CONCLUSION

Symptomatic iatrogenic ACJ instability following DCE is rare. Arthroscopically assisted revision surgery with an autologous hamstring graft improved ACJ stability in eight out of nine cases (88.9%). However, the functional scores showed ongoing impairment of shoulder function and a relatively high overall complication rate (33.3%). Therefore, this study underlines the importance of precise preoperative indication and planning and, especially, the preservation of ACJ stability when performing AC joint resection procedures.

LEVEL OF EVIDENCE

Case series, LEVEL IV.

Anatomic Acromioclavicular Joint Reconstruction with and without Acromioclavicular Ligament Reconstruction: A Comparative Biomechanical Study

Background

The purpose of this study was to determine if adding a reconstructed superior acromioclavicular (AC) joint ligament adds significant biomechanical stability to the AC joint over anatomic coracoclavicular (CC) ligament reconstruction alone.

Methods

Fourteen cadaver shoulders were used for the comparison of biomechanical stability among the anatomic CC ligament reconstruction alone, CC and AC ligament reconstruction, and the intact groups by measuring the displacement under cyclic loads. A load to failure test was then performed in the vertical direction at a loading rate of 2 mm /sec to determine surgical-repair joints' tolerance to the maximum failure load.

Results

The average peak-to-peak displacement induced by cyclic load in the sagittal axis and vertical axis direction was not significantly different between CC ligament reconstruction, CC and AC ligament reconstruction, and intact groups. The maximum failure load for the CC reconstruction (224.9 ± 91.8 N (Mean ± SEM)) was lower than CC/AC reconstruction groups (326.2 ± 123.3 N). The CC/AC reconstruction group failed at a significantly higher load (t test, p = 0.016) than the CC reconstruction group.

Conclusion

CC/AC reconstruction surgical technique yielded a better shoulder stability than CC ligament alone reconstruction that may better maintain reduction of the AC joint.Level of Evidence: Level II.

The Reliability of Acromioclavicular Joint Dislocation Classification Systems: A Comparison Between the Rockwood and Kraus Classifications

Background

The Rockwood system for the classification of acute acromioclavicular (AC) joint dislocations has been associated with a lack of reliability. A novel system has been proposed (Kraus classification) that is based on dynamic posterior translation of these injuries.

Purpose

To assess the interobserver and intraobserver reliability of the Rockwood and Kraus classification systems and also to examine the impact of surgeon experience on the assessments.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

Included were 45 patients with acute AC joint injuries who underwent a radiographic examination using standard bilateral AP and modified Alexander views. For interobserver reliability, 6 shoulder surgeons (expert group) and 6 orthopaedic residents (novice group) reviewed the radiographs to classify injuries according to the Rockwood and Kraus classifications; for each categorization, the participants chose between nonoperative management and surgical treatment. The evaluation was repeated 6 weeks later to determine intraobserver reliability. Kappa (κ) coefficients and their 95% CIs were used to compare interobserver and intraobserver reliability for each classification system according to assessor experience. Statistical differences were considered significant when the upper and lower boundaries of the 95% CI did not overlap.

Results

The overall interobserver agreement for diagnosis (both novice and expert groups) was moderate (κ = 0.52 [95% CI, 0.51-0.54]) for the Rockwood classification and substantial (κ = 0.62 [95% CI, 0.53-0.65]) for the Kraus classification; however, no significant differences were observed between the κ values. The overall interobserver agreement for treatment selection was substantial when using both the Rockwood (κ = 0.78 [95% CI, 0.72-0.81]) and Kraus (κ = 0.77 [95% CI, 0.66-0.87]) classifications. The overall intraobserver agreement for diagnosis was substantial using both the Rockwood (κ = 0.65 [95% CI, 0.61-0.67]) and Kraus (κ = 0.73 [95% CI, 0.69-0.75]) classifications. There were no significant differences between the novice and expert groups on any of the evaluations.

Conclusion

The Kraus system was slightly more reliable than the Rockwood system for classifying AC joint injuries both between assessor groups and overall. The level of surgeon experience had no impact on the evaluations.

Editorial Commentary: Coracoclavicular Joint Reconstruction for Acromioclavicular Dislocation: Double-Bundle Techniques Are Anatomically and Biomechanically Favored

For coracoclavicular (CC) joint reconstruction in the setting of acute acromioclavicular (AC) joint Rockwood type III or V dislocations, flexible fixation shows better clinical outcomes and complication rates than rigid fixation. Single-bundle CC reconstruction reconstructs the conoid ligament but poorly controls anteroposterior stability and is nonanatomic in nature. Thus, we favor double-bundle CC reconstruction incorporating a trapezoid bundle, replicating the broad insertion of the CC ligaments. Biomechanical data confirm improved stability with double-bundle, flexible fixation reconstruction, especially with the lateral clavicular tunnel in a more posterolateral location. An early clinical outcome study supports the double-bundle approach; meticulous surgical technique is required to avoid double-trouble complication rates.

Biomechanical Efficacy of Tape Cerclage as an Augment or Stand-alone for Coracoclavicular Ligament Reconstruction

BACKGROUND

Loss of initial reduction of the acromioclavicular joint after coracoclavicular (CC) ligament reconstruction remains a challenge for various repair techniques. Previous studies using polydioxanone suture cerclage augments for CC ligament reconstruction demonstrated poor clinical and biomechanical outcomes. Tape-style sutures have recently gained popularity because of their added stiffness and strength relative to traditional sutures. These tape cerclage systems have yet to be biomechanically studied in CC ligament reconstruction.

PURPOSE

To determine the efficacy of a tape cerclage system as an augment to CC ligament reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 24 human cadaveric shoulders were utilized. These were divided into 4 repair groups: anatomic CC ligament reconstruction (ACCR), ACCR with a tape cerclage augment (ACCR + C), tendon graft sling with a cerclage augment (TGS + C), or tape cerclage sling alone (CS). The repairs underwent superior/inferior cyclic loading to evaluate for displacement. Specimens were visually inspected for cortical erosion by the tape cerclage after cyclic loading. Finally, the constructs underwent superior plane load-to-failure testing.

RESULTS

Less displacement after cyclic loading was observed in the ACCR + C (mean ± SD, 0.42 ± 0.32 mm), TGS + C (0.92 ± 0.42 mm), and CS (0.93 ± 0.39 mm) groups as compared with the ACCR group (4.42 ± 3.40 mm; P = .002). ACCR + C (813.3 ± 257.5 N), TGS + C (558.0 ± 120.7 N), and CS (759.5 ± 173.7 N) demonstrated significantly greater load at failure relative to ACCR (329.2 ± 118.2 N) (P < .001). ACCR + C (60.88 ± 17.3 N/mm), TGS + C (44.97 ± 9.15 N/mm), and CS (54.52 ± 14.24 N/mm) conferred greater stiffness than ACCR (27.43 ± 6.94 N/mm) (P = .001). No cortical erosion was demonstrated in any specimen after cyclic loading.

CONCLUSION

In a cadaveric model at time zero, repairs utilizing a tape cerclage system confer significantly greater load to failure and stiffness, as well as decreased displacement with cyclic loading, when compared with traditional ACCR repair.

CLINICAL RELEVANCE

Tape cerclage augmentation may provide a useful augment for CC ligament reconstruction.

Bone tunnel placement influences shear stresses at the coracoid process after coracoclavicular ligament reconstruction: a finite element study and radiological analysis

INTRODUCTION

Coracoid fractures after arthroscopic treatment of acromioclavicular (AC) joint separations lead to poor clinical outcomes. In this study, different configurations of bone tunnels in the lateral clavicle and coracoid were examined concerning the amount of stress induced in the coracoid.

METHODS

An authentic 3D finite element model of an ac joint was established. Three 2.4 mm bone tunnels were inserted in the lateral clavicle, which were situated above, medially and laterally of the coracoid. Then, two 2.4 mm bone tunnels were inserted in the latter, each simulating a proximal and a distal suture button position. Von Mises stress analyses were performed to evaluate the amount of stress caused in the coracoid process by the different configurations. Then, a clinical series of radiographs was examined, the placement of the clavicle drill hole was analyzed and the number of dangerous configurations was recorded.

RESULTS

The safest configuration was a proximal tunnel in the coracoid combined with a lateral bone tunnel in the clavicle, leading to an oblique traction at the coracoid. A distal bone tunnel in the coracoid and perpendicular traction as well as a proximal tunnel in the coracoid with medial traction caused the highest stresses. Anatomical placement of the clavicle drill hole does lead to configurations with smaller stresses.

CONCLUSION

The bone tunnel placement with the smallest amount of shear stresses was found when the traction of the suture button was directed slightly lateral, towards the AC joint. Anatomical placement of the clavicle drill hole alone was not sufficient in preventing dangerous configurations.

LEVEL OF EVIDENCE

Controlled laboratory study.

ANATOMICAL AND BIOMECHANICAL ROLE OF STATIC STABILIZERS OF THE ACROMIOCLAVICULAR JOINT

OBJECTIVE

The aim: To determine the anatomical and biomechanical significance of the static stabilizers of the acromioclavicular joint by conducting numerical modeling using the finite element method and experimental investigation.

PATIENTS AND METHODS

Materials and methods: To ensure the study, modeling of the deformation processes of the clavicle and scapula systems with various combinations of ligament damage was conducted. The COMPAS-3D software package was used to build the simulation model, which allowed obtaining models that are closest to reality. To verify the results of the numerical modeling, corresponding studies of the mechanical characteristics and determination of the stiffness of the investigated systems were carried out using the upgraded TIRAtest-2151 testing stand.

RESULTS

Results: The stiffest system is the system in which all ligaments are intact, and the sequence of decreasing stiffness of the system is presented in the following order: damage to lig. trapezoideum; lig. conoideum; lig. claviculo-acoacromiale inferior; lig. claviculo-acoacromiale superior; the coracoclavicular ligament complex; the acromioclavicular ligament complex.

CONCLUSION

Conclusions: Static stabilizers in general, and their components in particular, are characterized by significant anatomical and functional features. The natural stabilization of the acromioclavicular joint is provided by their synergistic interaction, which is the basis for the development and implementation of surgical interventions, the scope of which includes the restoration of both ligament complexes. The loss of stiffness in the «clavicle-scapula» system is significantly more pronounced when lig. acromioclaviculare superior and inferior are damaged (8.5 N/mm) than when lig. conoideum and lig. trapezoideum are damaged (11.6 N/mm).