Epidemiologie, Anatomie, Biomechanik und Bildgebung von Akromioklavikulargelenkverletzungen

Current techniques of acromioclavicular (AC) joint repair primarily focus on the reconstruction of the coracoclavicular (CC) ligaments. However, it is not clear if this approach is sufficient to restore vertical as well as horizontal AC joint stability and kinematics. This review focuses on the epidemiology of AC joint injuries and the coincidence of intra-articular pathologies. Furthermore, the clinically relevant anatomy and the pathomechanism of AC joint instability are described. The biomechanical characteristics of current procedures as they have been revealed by in vitro investigations are summarized. As a basic result, neither selective repair of the CC ligaments nor selective repair of the AC ligaments could be shown to restore both vertical and horizontal joint stability. Similar to the intact ligaments CC repair primarily provides vertical joint stability while AC repair is able to restore horizontal stability. In conclusion a biomechanically effective treatment of AC joint separation should analyze the individual instability pattern in the first step. Therefore, the radiological standard according to Rockwood should be supplemented by specific stress x-rays for quantification of dynamic horizontal AC joint instability. In the second step an adequate surgical treatment considering CC and AC stabilization should be performed meeting the individual patient requirements.     

Biomechanik aktueller Rekonstruktionstechniken bei Schultereckgelenksprengungen

Current techniques for acromioclavicular (AC) joint repair primarily focus on the reconstruction of the coracoclavicular (CC) ligaments. However, it is unclear whether this approach is sufficient to restore vertical as well as horizontal AC joint stability and kinematics. Therefore, this review summarizes the biomechanical characteristics of current procedures as they have been revealed by in vitro investigations. As a basic result, neither selective repairs of the CC ligaments nor selective repairs of the AC ligaments could be shown to restore both vertical and horizontal joint stability. Similar to the intact ligaments, CC repair primarily provides vertical joint stability, while AC repair is able to restore horizontal stability. Thereby, the lack of horizontal stability of the CC repairs could not be compensated using tendon grafts, double-bundle techniques, and flip-button fixation. In conclusion, a biomechanical effective treatment of AC joint separation should analyze the individual instability pattern in the first step. In the second step, an adequate surgical treatment considering CC and AC stabilization should be performed meeting the individual demands.     

Editorial Commentary: Arthroscopic-Assisted Coracoclavicular Ligament Reconstruction Leads to Improved Patient-Reported Outcomes,But Patient Satisfaction Is a Harder Threshold to PASS

There are numerous described techniques for surgical management of high-grade acromioclavicular (AC) joint injuries, and the associated clinical outcomes can be quite variable. Contemporary techniques are typically directed at anatomic reconstruction of the coracoclavicular (CC) ligaments through either an arthroscopy-assisted or an open approach. Most patients treated with acute surgery improve, whereas in chronic cases, the majority improve, but a significant number have persistent recurrent deformity due to loss of anatomic reduction. In addition, whether acute or chronic, over one quarter of patients do not have a PASS (patient acceptable symptomatic state). Of interest, PASS may not primarily be related to the final deformity in terms of coracoclavicular distance, and investigation is still required in terms of the effect of anteroposterior or rotational instability of the AC joint after injury and surgery. Finally, PASS values for AC separation are not well established, resulting in a current limitation of the strength of applying threshold values to this pathology.     

Akute Sprengung des Akromioklavikulargelenks

Dislocation of the acromioclavicular joint (AC joint) is a typical sports injury with rupture of the acromioclavicular and coracoclavicular ligaments which may result in a vertical and horizontal instability of the lateral clavicle. Stress X-rays may be of help for the diagnosis of vertical instability and for the diagnostics axial or Alexander views should be made. In the future magnetic resonance imaging (MRI) will play a significant role for the diagnostics of AC joint injuries. With this method injuries of ligaments, fascia and the glenohumeral joint can be diagnosed. There is controversy regarding the therapy of AC joint injuries. For slight injuries a conservative treatment is recommended, for medium degree instability there is too little evidence in the literature to give a clear recommendation whether conservative or operative treatment is superior and for severe instability an operative treatment is recommended. For operative treatment several techniques have been described. Some techniques have a high complication rate and implant removal is also disadvantageous. These disadvantages led to the development of minimally invasive or arthroscopic techniques. The first clinical results of these new techniques are encouraging.     

Biomechanical analysis of acromioclavicular joint dislocation repair using coracoclavicular suspension devices in two different configurations

BackgroundThe best treatment option for some acromioclavicular (AC) joint dislocations is controversial. For this reason, the aim of this study was to evaluate the vertical biomechanical behavior of two techniques for the anatomic repair of coracoclavicular (CC) ligaments after an AC injury.ResultsGroup I reached a maximum force to failure of 635.59 N (mean 444.0 N). The corresponding force was 939.37 N (mean 495.6 N) for group II and 533.11 N (mean 343.9 N) for group III. A comparison of the three groups did not find any significant difference despite the loss of resistance presented by group III.ConclusionAnatomic repair of coracoclavicular ligaments with a double system (double tunnel in the clavicle and in the coracoid) permits vertical translation that is more like that of the acromioclavicular joint. Acromioclavicular repair in a “V” configuration does not seem to be biomechanically sufficient.     

Aktuelle operative Therapiestrategien bei chronischer Akromioklavikularsgelenkinstabilität

Chronic instability of the acromioclavicular joint (AC joint) results if the initial acromioclavicular joint luxation has been missed or if the rehabilitative or surgical treatment was not successful. Late repairs after a traumatic luxation are difficult to deal with because the biological healing response for reconstitution of the ligaments seems to be compromised. A meticulous diagnostic examination should be performed paying special attention to the character and direction of instability (static versus dynamic and vertical versus horizontal). For this purpose a specified classification system should be used (Hedtmann and Heers). A new surgical technique for stabilization of chronic AC joint instability has been established and biomechanically evaluated. The technique includes an augmented modified coracoacromial ligament (only the medial half of the ligament) transfer supplemented by coracoclavicular polyester augmentation. In an in vitro model the technique was shown to restore anterior and superior translation of the intact AC joint. An increase of translation compared to the level of the intact joint was statistically significant only for the posterior direction (127%, 3.8 mm intact versus 4.6 mm following reconstruction; p<0.05). Therefore, for further improvement of the technique some form of acromioclavicular ligament reconstruction (posterosuperior) could be profitable. In conclusion the presented surgical technique (augmented CA ligament transfer) reveals promising biomechanical results in an in vitro model and may serve as an alternative to current coracoclavicular ligament reconstruction techniques using autologous tendon grafts.     

Editorial Commentary: Why We Have To Respect The Anatomy In Acromioclavicular Joint Surgery And Why Clinical Shoulder Scores Might Not Give Us The Information We Need!

Over the past decade, the interest in acromioclavicular (AC) joint research has experienced a revolutionary increase. Biomechanical and anatomic studies have been carried out to investigate and obtain a better understanding of the function of this joint. The reason for this huge investigational effort is the fact that we do not have any gold standard for the treatment, diagnosis, or follow-up of patients with acute or chronic AC joint injuries. This is reflected by the huge number of over 160 different surgical techniques described in the literature. So far, we have a variety of anatomic procedures, nonanatomic procedures, and nonanatomic procedures with open reduction and internal fixation, with a significantly better clinical outcome for anatomic techniques. Because of this wide variety, it is hard and nearly impossible to compare clinical data. Within the past 5 years, we have focused not only on the vertical instability but also, more and more, on the horizontal instability and tried to understand the rotational component of this joint with the importance of scapulothoracic motion. The evolutionary advantage of bipedalism with the support of the clavicle compared with quadrupedalism allows us to lift our arms for overhead activities. Therefore, we need an intact sternoclavicular and AC force transfer, described as the “strut function,” to give a resistance against the thorax when abducting the arm over 90°. Once we have an interruption in this force transfer, we believe that it is the most important aspect in AC joint surgery to try to anatomically restore this joint's anatomy. For this reason, we have changed our practice in the past few years in line with the newly derived data, by addressing the coracoclavicular ligaments as well as the AC capsule to restore horizontal and vertical stability but also allow for physiological rotation and movement.     

Verletzungen und Erkrankungen des Akromioklavikulargelenkes

Osteoarthritis or instability of the acromioclavicular (AC) joint may cause significant impairment or pain in the shoulder. If symptoms of osteoarthritis persist despite conservative treatment, distal clavicular resection is usually curative. Injuries and instability are classified according to Rockwood. Treatment of mild instability due to trauma is nonoperative. An underestimated acute injury to the AC joint may result in chronic instability. Different techniques are presented for operative treatment of significant acute or chronic instability. Arthroscopic methods are now available for treating both acute and chronic instability.     

Surgical reconstruction of the acromioclavicular joint: Can we identify the optimal approach?

Injuries to the acromioclavicular (AC) joint are common, tending to occur secondary to traumatic injuries. Rockwood grade IV, V and VI injuries involve complete dislocation of the joint and require surgical reconstruction, with inconclusive literature on whether grade III injuries should be surgically or conservatively managed. There are over one hundred reported surgical techniques which reconstruct the AC joint, with little indication of which methods achieve the best results. Techniques can generally be considered as: anatomical reduction; CC ligament reconstruction; and anatomical reconstruction. Techniques which implant hardware to reduce the AC joint, such as the hook plate, are commonly implemented, but have been shown to alter the mechanics of the joint significantly, resulting in poor short-term and long-term outcomes. Methods which reconstruct both the acromioclavicular and coracoclavicular ligaments are comparatively new, and early reports suggest that they achieve biomechanical properties similar to the native joint. More focus should be placed on such techniques in the future to determine whether they offer a more suitable approach to improve patient outcomes following AC joint reconstruction.     

Anatomie der akromiokorakoklavikulären Region

Background

The acromioclavicular (AC) joint connects the acromion with the lateral end of the clavicle and constitutes an important load-transmitting element between the upper extremity and the skeleton of the trunk.

Aim

This review discusses functional aspects that relate the AC and the coracoclavicular (CC) ligaments to AC joint instability and lateral clavicle fracture.

Results

In terms of stability the AC and CC ligaments play a pivotal role for this region. Under normal conditions the restraint system is balanced and becomes unbalanced in cases of injury such as AC joint instability or lateral clavicular fractures. Skeletal injuries frequently affect the ligaments with their usually sharp-angled insertion sites, which alters the function of the restraint system. As a consequence these injuries lead to multidirectional dislocating forces acting on the scapula in relationship to the lateral end of the clavicle. Previously, special attention was given to the vertical dislocation of the lateral clavicle, whereas less attention was paid to other factors which could lead to dislocation in other directions. Therefore, in this review emphasis is placed on the anatomical principles of multidirectional dislocation of the AC joint the fractured lateral clavicle.

Conclusion

Current clinical classification schemes fail to sufficiently include these multidirectional dislocating forces; however, they have to be considered when choosing the appropriate treatment modality. Thus, understanding the anatomical and functional context of the AC/CC region is essential for a sound management of AC joint injuries and fractures of the distal clavicle.

     

Clavicle and coracoid process drilling technique for truly anatomic coracoclavicular ligament reconstruction

Background

High-grade acromioclavicular (AC) joint separations require surgical treatment, as conservative treatment may result in functional decline or persistent pain. Although many surgical techniques have been described in the literature, there is still no non-controversial gold standard procedure for AC joint dislocation. The different orientation of the two components of the coracoclavicular (CC) ligaments has been proven to account for different functions. However, the majority of the techniques reconstruct the CC ligaments with a single structure. The purposes of this study were to assess the feasibility of truly anatomic coracoclavicular ligament reconstruction (TACCR) and to determine the corresponding drilling parameter.

Methods

We constructed virtual three-dimensional (3D) models of 105 shoulders from computed tomography (CT) scan data by using SuperImage software. For each model, the attachment sites and footprint dimensions of the conoid and trapezoid ligaments were defined and adjusted according to previously defined anatomic parameters and individual measurement results. Virtual drilling and 3D measurement were carried out in each model separately. Guided by the drilling parameter, we performed TACCR on 24 shoulders from 12 whole cadavers after transecting the AC and CC ligaments.

Results

The collinear drilling technique was noted to breach the bone cortex of the clavicle and/or the coracoid process in 95 of 105 virtual models (90.5%). No cortical breach was observed using a non-collinear drilling technique. The anteversion angulation of the conoid–coracoid tunnel ranged from 10° to 15° (mean value 12.4°). The extraversion angulation of the conoid–coracoid tunnel varied from 5° to 10° (mean value 6.8°). The anteversion angulation of the trapezoid–coracoid tunnel ranged from 20° to 30° (mean value 25.2°). There were no failures when performing the non-collinear drilling technique on cadaver models.

Conclusions

The collinear drilling technique is not technically feasible for TACCR. For this reason, we recommend the non-collinear drilling technique, which provides the ability to prepare bony tunnels without any risk of cortical breach.

Clinical relevance

Based on this computer and cadaver model study, we have devised a novel drilling technique to restore the CC ligaments anatomically.     

Die laterale Klavikulafraktur – Grundlagen,OP-Indikationen,Versorgungstechniken

Fractures of the lateral clavicle are a rare entity and can usually be treated conservatively. Only dislocated fractures with disrupted coracoclavicular (CC) ligaments may require operative treatment. Many different surgical techniques have been described. The use of hook plates and k-wires is associated with higher complication rates. Similar to acromioclavicular (AC) joint dislocation, there is a trend towards minimally invasive and arthroscopically assisted procedures. The functional results are promising and the complication rates are low. From a biomechanical point of view, a combination of locked plate fixation and minimally invasive CC ligament reconstruction provides the highest stability. Newly developed preshaped angular stable implants may provide higher stability but are associated with implant-related soft tissue irritation and hardware removal is required more frequently.     

Arthroscopic anatomical reconstruction of the acromioclavicular joint

Traditional techniques for restoration of a separated acromioclavicular joint are afflicted with various complications and often lead to recurrent dislocation. Lately, anatomic as well as minimally-invasive repair techniques with major focus on restoration of the coracoclavicular ligaments have been described for acromioclavicular joint reconstruction. We present a technique for an arthroscopically-assisted anatomical acromioclavicular joint reconstruction by replacing the conoid and trapezoid separately with nonabsorbable sutures and titanium buttons.     

Biomechanical Comparison of an Intramedullary and Extramedullary Free-Tissue Graft Reconstruction of the Acromioclavicular Joint Complex

Background

Several different surgical techniques have been described to address the coracoclavicular (CC) ligaments in acromioclavicular (AC) joint injuries. However, very few techniques focus on reconstructing the AC ligaments, despite its importance in providing stability. The purpose of our study was to compare the biomechanical properties of two free-tissue graft techniques that reconstruct both the AC and CC ligaments in cadaveric shoulders, one with an extramedullary AC reconstruction and the other with an intramedullary AC reconstruction. We hypothesized intramedullary AC reconstruction will provide greater anteroposterior translational stability and improved load to failure characteristics than an extramedullary technique.

Methods

Six matched cadaveric shoulders underwent translational testing at 10 N and 15 N in the anteroposterior and superoinferior directions, under AC joint compression loads of 10 N, 20 N, and 30 N. After the AC and CC ligaments were transected, one of the specimens was randomly assigned the intramedullary free-tissue graft reconstruction while its matched pair received the extramedullary graft reconstruction. Both reconstructed specimens then underwent repeat translational testing, followed by load to failure testing, via superior clavicle distraction, at a rate of 50 mm/min.

Results

Intramedullary reconstruction provided significantly greater translational stability in the anteroposterior direction than the extramedullary technique for four of six loading conditions (p < 0.05). There were no significant differences in translational stability in the superoinferior direction for any loading condition. The intramedullary reconstructed specimens demonstrated improved load to failure characteristics with the intramedullary reconstruction having a lower deformation at yield and a higher ultimate load than the extramedullary reconstruction (p < 0.05).

Conclusions

Intramedullary reconstruction of the AC joint provides greater stability in the anteroposterior direction and improved load to failure characteristics than an extramedullary technique. Reconstruction of the injured AC joint with an intramedullary free tissue graft may provide greater strength and stability than other currently used techniques, allowing patients to have improved clinical outcomes.     

Post-traumatic acromioclavicular instability reconstruction with coracoacromial ligament and conjoined tendon: A preliminary report

BackgroundMany surgical techniques have been proposed to treat acromioclavicular (AC) injuries; however, anatomic coracoclavicular (CC) reconstructions with local tissue grafts have not been reported in previous studies. The aim of this study was to investigate early outcomes of this innovative technique.MethodsBetween 2004 and 2011, 15 patients with post-traumatic AC instability underwent anatomic reconstructions by two surgeons at our institution. Nine patients were treated with local tissue grafts, and these included six patients who underwent double-bundle reconstructions and three who underwent single-bundle reconstructions. The remaining six patients were treated with free tendon grafts. The clinical outcomes of the Constant scores and the radiographic results of the CC distance were further analyzed.ResultsIn patients who underwent reconstructions with local tissue grafts, those treated with double-bundle and selective-bundle reconstructions had an average postoperative Constant score of 89.0 ± 11.5 and 71.7 ± 38.4, respectively. In patients who underwent reconstructions with free tendon grafts, the average score was 73.0 ± 29.4. There was no statistically significant difference among the three reconstruction procedures. Only one patient showed residual AC separation on plain-film radiography.ConclusionThis innovative technique provided clinical and radiographic results that were comparable to those achieved with free tendon grafts. This procedure can be an alternative surgical option for treating AC joint instability.     

Triple endobuttton technique for the treatment of acute complete acromioclavicular joint dislocations: preliminary results

Numerous procedures have been described for the operative management of acromioclavicular (AC) joint injuries. Some of these techniques, including hardware fixation and non-anatomical reconstructions, are associated with serious complications and high failure rates. Recently, AC joint reconstruction techniques have focused on anatomical restoration of the coracoclavicular ligaments to achieve optimal clinical outcomes. We used a triple endobutton technique to separately reconstruct the trapezoid and the coronoid portions of the coracoclavicular ligament. We evaluated the preliminary clinical and radiological results of this technique in patients with acute complete dislocation of the AC joint. All patients achieved a significant improvement in the pain and function of shoulder at a mean follow-up interval of 12 months (range, 8–14 months). Excellent reduction of the AC joint was maintained. The triple endobutton technique may be safe and effective for the treatment of acute complete AC joint dislocations.     

Biomechanical function of surgical procedures for acromioclavicular joint dislocations

PurposeSurgical procedures for treatment of acromioclavicular (AC) joint dislocation replace the coracoclavicular (CC) ligaments to minimize motion, allow scarring, and increase the subsequent stability of the joint. The purpose of this study was to evaluate the biomechanical function of the surgically repaired or reconstructed (CC Sling, Rockwood Screw [DePuy Orthopaedics, Warsaw, IN], and Coracoacromial [CA] Ligament Transfer Construct) AC joint after AC joint dislocation.Type of StudyA cadaver study using a convenience sample.MethodsTwelve cadaveric shoulders were tested using a robotic/UFS testing system. Three external loading conditions (anterior, posterior, or superior load of 70 N) were applied to intact and surgically repaired or reconstructed AC joint. The resulting kinematics of the AC joint and in situ forces in the CC ligaments or surgical constructs was determined.ResultsFor the CC Sling, anterior and posterior translation significantly increased by 110% and 330% in response to an anterior and posterior load, respectively. However, the posterior translation for the Rockwood Screw significantly decreased by 60%. Anterior, posterior, and superior translation for the CA Ligament Transfer Construct significantly increased by 110%, 360%, and 100%, respectively. The coupled translations also significantly increased for the CC Sling and CA Ligament Transfer Construct in response to all loading conditions. In contrast, the coupled translations for the Rockwood Screw tended to decrease. Furthermore, the in situ forces increased significantly for all 3 surgical constructs compared with the intact CC Ligaments in response to an anterior and posterior load.ConclusionsAt time zero, increases in the primary and coupled motion for the CC Sling and CA Ligament Transfer Construct could comprise the initial healing period prescribed for AC joint dislocation. Our findings also suggest that the Rockwood Screw provides a highly rigid fixation and may explain the complications frequently seen in clinical practice.Clinical RelevanceCurrent surgical procedures do not have the appropriate stiffness to restore the stability of the intact joint before healing. Therefore, our results may lead to the design and development of new repairs, reconstructions, and rehabilitation protocols for AC joint dislocation.     

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.     

The Munich Shoulder Questionnaire (MSQ): development and validation of an effective patient-reported tool for outcome measurement and patient safety in shoulder surgery

Purpose

In this retrospective study we investigated the clinical and radiological outcome after operative treatment of acute Rockwood III-V injuries of the AC-joint using two acromioclavicular (AC) cerclages and one coracoclavicular (CC) cerclage with resorbable sutures.

Methods

Between 2007 and 2009 a total of 39 patients fit the inclusion criteria after operative treatment of acute AC joint dislocation. All patients underwent open reduction and anatomic reconstruction of the AC and CC-ligaments using PDS? sutures (Polydioxane, Ethicon, Norderstedt, Germany). Thirty-three patients could be investigated at a mean follow up of 32±9?months (range 24?C56?months).

Results

The mean Constant score was 94.3±7.1 (range 73?C100) with an age and gender correlated score of 104.2%±6.9 (88-123%). The DASH score (mean 3.46±6.6 points), the ASES score (94.6±9.7points) and the Visual Analogue Scale (mean 0.5±0,6) revealed a good to excellent clinical outcome. The difference in the coracoclavicular distance compared to the contralateral side was <5?mm for 28 patients, between 5-10?mm for 4 patients, and more than 10?mm for another patient. In the axial view, the anterior border of the clavicle was within 1?cm (ventral-dorsal direction) of the anterior rim of the acromion in 28 patients (85%). Re-dislocations occured in three patients (9%).

Conclusion

Open AC joint reconstruction using AC and CC PDS cerclages provides good to excellent clinical results in the majority of cases. However, radiographically, the CC distance increased significantly at final follow up, but neither the amount of re-dislocation nor calcifications of the CC ligaments or osteoarthritis of the AC joint had significant influence on the outcome.

Level of evidence

Case series, Level IV