Abstract
Background
A number of surgical techniques for the treatment of acromioclavicular joint separations have been described; however, few have been able to create a strong intra-operative construct that provides minimal joint translation. A biomechanical study was conducted to examine joint translation in an independent acromioclavicular ligament repair.
Methods
Three variations of a novel independent acromioclavicular ligament repair technique underwent testing using a Sawbones model. The technique involves threading sutures through two acromial bone tunnels in a suture-bridge configuration and anchoring them into the distal clavicle. Three groups of eight specimens underwent reconstruction; group 1 using FiberTape, group 2 using FiberWire and group 3 using FiberTape in a modified (under-over) suture-bridge configuration. Superior, anterior and posterior translation was tested at loads of 10, 20 and 30 N.
Results
Group 3 repair yielded the least translation in both anterior–posterior and superior–inferior planes, with a two-fold decrease in superior translation compared to groups 1 and 2 (P < .05). Both groups 1 and 3 using FiberTape resulted in significantly less anterior and posterior translation compared to the FiberWire group (P < .05).
Discussion
The independent acromioclavicular ligament repair, without repair of the coracoclavicular ligament, demonstrated significant translational stability in the anterior–posterior and superior–inferior planes.
Keywords: acromioclavicular joint, dislocation, independent acromioclavicular reconstruction, shoulder, biomechanical
Introduction
An injury to the acromioclavicular joint (ACJ) occurs relatively frequently, accounting for 9% of all injuries sustained to the shoulder girdle. These injuries are most common in young athletes, particularly those involved in contact and collision sports. They often occur as a consequence of direct trauma to the tip of their shoulders, either from impact with another player or from an awkward fall.1,2
AC joint separations are typically classified according to the Rockwood Classification, a classification based on ligamentous injury and AC joint dislocation, which in turn dictates management options.3 AC joint injuries that result in partial ligament tear or complete tear of the AC ligament alone (type I and II) are often managed conservatively, with minimal intervention yielding excellent results.4 Those joints that are widely separated (type III, IV, V and VI), associated with complete tears of the acromioclavicular (AC) and coracoclavicular (CC) ligaments, often require surgical management to achieve stabilisation. There have been a large number of surgical techniques utilised for AC stabilisation: fixation with metallic hardware, distal clavicle resection with ligament transfer, augmentations using allograft, autograft, heavy suture and surgical tape, as well as anatomic CC ligament repairs using synthetic grafts. However, very few have been able to create a strong intra-operative construct that provides minimal joint translation with limited additional complications.
At present, most surgical techniques for ACJ stabilisation primarily focus on anatomic reconstruction of the CC ligaments alone. However, with increased understanding of the biomechanical significance of the AC ligaments for horizontal stability,5–9 techniques have begun combining CC ligament repair with concomitant AC ligament repair. These techniques have shown increased joint stability in the horizontal plane compared to CC ligament repair alone; however, a significant proportion of patients still suffered from posterior subluxation of the ACJ with this technique, which has been associated with significant shoulder pain10 as well as inferior clinical outcomes.11 Complications associated with CC ligament repairs, including hardware failure and fractures, are also common.12
Utilising understanding from a recent anatomical study by Nakazawa et al.,1 which detailed the correct anatomical orientation of the AC ligaments, coupled with advancements in suture and anchor systems, a novel surgical technique was devised. The technique proposed anatomical reconstruction of the AC ligaments alone, disregarding the routinely repaired CC ligaments. This was proposed on the premise that a technique that solely focuses on reconstruction of the AC ligaments could potentially ensure greater horizontal stability whilst simultaneously providing significant vertical stability, without the added complications often associated with CC ligament repair. The aim of this study was to biomechanically evaluate this novel surgical construct, examining whether an independent AC ligament repair will minimise joint translation in both the anterior–posterior and superior–inferior planes when placed under mechanical stress. The study also endeavoured to determine whether a normal #2 suture or a wider suture tape was more suitable for use in this repair technique in creating translational stability. We hypothesised that the technique would restore joint stability to a comparable extent to that of the native ACJ, despite the technique ignoring reconstruction of the CC ligaments.
Materials and methods
ACJ reconstruction model
Antero–posterior (AP) and supero–inferior (SI) ACJ translations for three variations of a novel AC joint reconstruction technique were evaluated using a Sawbones shoulder girdle model (Pacific Research Laboratory Inc., Vashon Island, Washington). The Sawbones model was chosen for this study as it is designed to replicate the anatomy and physical properties of bone, whilst maintaining specimen consistency, ensuring the techniques being investigated could be reliably compared. Twenty-four left scapulae (Model#1021) and clavicle (Model#1020) Sawbones models were used in the study.
Power analysis
Data from a similar biomechanical study by Deshmukh et al.,13 which compared a number of ACJ repair techniques, were used to calculate the sample size for this study. In order to detect a significant translational difference of 5.6 mm (SD of 3.0 mm) between repair techniques, a sample size of at least six specimens was needed in each group based on a one-way analysis of variance sample size calculation, with α set to 0.05 and a power of 0.8.
Specimen preparation
Each clavicle (Model#1020, Pacific Research Laboratory Inc., Vashon Island, Washington) was potted in a 4 cm square aluminium tube using high strength self-mixing two-part hybrid polyurethane (Ardit Rapidset Cement) (Ardex, Seven Hills, NSW) from the sternal end till a level of the conoid tubercle, and allowed to set overnight. This ensured that key bony landmarks of the distal clavicle were adequately exposed for ACJ reconstruction, whilst securing enough of the clavicle to prevent clavicular bending during testing.
For specimen reconstruction, a 3.0 mm hole was drilled through the superior aspect of the acromion set 10 mm in from the anterior border and 10 mm in from both the medial and lateral borders. Another 3.0 mm hole was drilled 20 mm posterior to the first hole in parallel to the AC joint facet (Figure 1). A guide was then created using a transparency sheet, to ensure that the holes could be accurately marked on the remaining Sawbones scapulae specimens. Following marking, the two holes were drilled into each of the remaining 23 specimen scapulae.
Figure 1.
Image of Sawbones scapula specimen with 3.0 mm drill holes in the acromion.
In preparation for reconstruction, pilot holes were drilled into the distal end of the potted clavicles for anchor positioning. To ensure anchor positioning was consistent amongst specimens, a jig was devised that locked the potted clavicles at an angle at which the distal clavicle could be easily drilled into. A transparent acrylic block was incorporated into the jig at the edge of the distal clavicle to standardise the horizontal and vertical angles of drilling across all specimens. Laser guides were set up in line with the acrylic pilot holes to further ensure the drill bit commenced in the correct angle. Using the jig, two 3.5 mm pilot holes were drilled into the distal clavicles of each of the potted specimens using a specialised Arthrex Spade Tip drill bit designed for 4.75 mm Arthrex SwiveLock anchors (Arthrex Inc., Naples, Florida).
Surgical reconstruction
Following completion of preparation to the Sawbones scapulae and potted clavicles, three variations of a novel surgical technique were performed for AC Joint reconstruction. Eight pairs of scapulae and clavicle were each randomly assigned to three different repair groups.
Group 1: Suture-bridge FiberTape (SBFT) repair
This repair was performed by threading two ends of FiberTape sutures (Arthrex Inc., Naples, Florida) through the anterior drill hole in the acromion from above, passing them below the acromion and out through the adjacent posterior drill hole from below. This meant that the four limbs of the FiberTape were extending from the superior aspect of the acromion. The limbs were then separated so that one of the limbs protruding from the anterior drill hole and one of the limbs from the posterior drill hole were grouped and the remaining limbs also grouped separately. The limbs were grouped in a way that ensured the two grouped ends did not belong to the same length of suture. This created a suture bridge configuration. Each of the two groups of suture ends were threaded through a SwiveLock closed eyelet atop of a SwiveLock anchor body. Anatomical positioning of the AC joint was determined and positioned. The FiberTape ends were tensioned and then driven into the predrilled hole that was located directly opposite the joint margin in the distal clavicle. The anchor was buried as far as possible into its pilot hole, ensuring a tight construct that reduced the AC joint to its anatomical positioning (Figure 2). The loose ends of the FiberTape were trimmed to length.
Figure 2.
A complete SBFT repair.
Group 2: Suture-bridge FiberWire (SBFW) repair
This repair group was performed using the same technique as the group 1 repair, however utilised #2 FiberWire (Arthrex Inc., Naples, Florida) suture as the material for reconstruction (Figure 3). This repair group functioned as a control group to help determine the relative strength of FiberTape compared to FiberWire suture in their AC joint reconstruction ability.
Figure 3.
A complete SBFW repair.
Group 3: Under-over suture-bridge FiberTape (UOSBFT) repair
This repair group was performed using FiberTape, as was used in the group 1 repair. The repair was a modification of the technique utilised for both group 1 and group 2. One end of the FiberTape suture was threaded through the anterior drill hole on the acromion from above, passed under the acromion and pulled up through the posterior drill hole. The other length of FiberTape suture was threaded through the anterior drill hole from below, passed across the superior aspect of the acromion and threaded down through the posterior drill hole. This left two of the limbs of the FiberTape suture extending from the superior aspect of the acromion and two of the limbs extending from the inferior aspect of the acromion. The limb extending from the superior aspect of the anterior drill hole was grouped with the limb extending from the inferior aspect of the posterior drill hole to be anchored into the posterior hole in the distal clavicle, whilst the limb extending from the inferior aspect of the anterior drill hole was grouped with the limb extending from the superior aspect of the posterior drill hole to be anchored into the anterior pilot hole in the distal clavicle. Anatomical positioning of the AC joint was determined and after tensioning the sutures, they were anchored into their respective holes in the distal clavicle (Figure 4).
Figure 4.
A complete UOSBFT repair.
Mechanical testing: Superior translation
For mechanical testing of the repaired specimens, the scapula was secured to a multi-directional vice clamp. The positioning of the multi-directional vice was adjusted until the clavicle was in a position that allowed for superior translational testing when attached to the load cell. The clavicle was secured to the load cell using two G-clamps, positioned at either end of the aluminium tube in which the clavicle was potted. Once positioning of the clavicle was set, the vice was secured to the base of the machine using step blocks, and was ready for testing.
Translational testing was performed with a mechanical tensile testing machine (Instron 8874) and measurements recorded via a computer connected to a load cell (10 kN Dynacell; Instron, Norwood, MA). The load cell was initially positioned to ensure there was no load through the specimen, with the recorded displacement reading used as the baseline measurement for testing of the particular specimen. Translation was then assessed at loads of 10, 20 and 30 N of force pulling the clavicle superiorly and results recorded. Testing was repeated.
Mechanical testing: Anterior–posterior translation
For testing of anterior–posterior translation, the scapula was once again secured in a multi-directional vice. The potted clavicle was mounted on the load cell, using two L-plates, which positioned the potted clavicle in a vertical plane. The potted clavicle was secured through the use of a single G-clamp compressing the potted clavicle between the two L plates. The vice was adjusted to ensure that the scapula, when secured, was positioned in a way that orientated anterior and posterior displacement of the clavicle in parallel with the line of pull of the load cell, whilst maintaining the anatomy of the AC joint. The vice was consequently secured to the base of the machine using step blocks.
As for superior testing, the testing machine was first micro-adjusted to ensure there was 0 N of load through the specimen. The baseline displacement at 0 N was recorded, and subsequently displacement recorded at 10, 20 and 30 N both anteriorly and posteriorly. Testing was repeated.
When testing specimen groups, a cross-over design was implemented (Table 1). This meant that primarily SI translation was tested, followed by AP translation for the first four specimens in each of the three groups, and for the remaining four specimens of the three groups AP translation was tested first followed by SI translation. Implementing this design into the testing protocol ensured that both the AP and SI translational data could be interpreted independently and would also give an indication if translational testing in one plane had an effect on data from testing in the other plane.
Table 1.
Cross-over design – the order of directional testing.
| Repair group | Specimen no. | Plane tested first | Plane tested second |
|---|---|---|---|
| SBFT | 1–4 | SI | AP |
| 5–8 | AP | SI | |
| SBFW | 9–12 | SI | AP |
| 13–16 | AP | SI | |
| UOSBFT | 17–20 | SI | AP |
| 21–24 | AP | SI |
AP: antero–posterior; SBFT: suture-bridge FiberTape; SBFW: suture-bridge FiberWire; SI: supero–inferior; UOSBFT: under-over suture-bridge FiberTape.
Mechanical testing: Pull to failure
Following translation testing, pull-to-failure tests were performed in the superior direction on each of the specimens using the mechanical tensile testing machine (Instron 8874) with a 10 kN Dynacell loadcell (Instron). Each specimen was secured using the same set up as was used for superior translation testing. The repairs were preloaded with 10 N for 30 s and then pulled at 50 mm/min to failure with the data captured at 100 Hz on a computer. The mode of failure was recorded for each of the specimens. Repair stiffness was calculated for each of the specimens from the linear portion of the load–displacement curve, generated on the computer during testing, using MATLAB software (R2016; The MathWorks, Natick, MA). Using the MATLAB software, the total energy to failure was also calculated from the area under the load–displacement curve.
Statistical analysis
Paired Student’s t-test was used to analyse the differences in translation and pull to failure between each of the three repair groups. Results are reported as mean ± SEM. The level of statistical significance was defined as P < .05.
Results
A reliability study was performed in the superior, anterior and posterior planes of testing to determine the inter-rater reliability and the ICC values were 0.85, 0.72 and 0.71, respectively, which showed that the testing system had excellent reliability.
Superior translation
The UOSBFT technique yielded significantly less superior translation of the clavicle (3.5 ± 0.2) than both the SBFT (7.3 ± 1.3, P = .016) and SBFW (8.6 ± 0.8, P < .001) techniques loaded at 30 N (Figure 5) (Table 2). There was however no statistically significant difference between the SBFT and SBFW groups for superior translation. Every 10 N increase in load leads to a significant increase in superior translation for all three repair techniques (P < .001).
Figure 5.
Mean (SEM) superior translation testing values for three variations of a novel independent AC ligament reconstruction at loads of 10, 20 and 30 N. SBFT: suture-bridge FiberTape; SBFW: suture-bridge FiberWire; UOSBFT: under-over suture-bridge FiberTape.
Table 2.
Translation at 30 N (mean ± SEM).
| Reconstruction type | Superior translation (mm) | Anterior translation (mm) | Posterior translation (mm) |
|---|---|---|---|
| SBFT | 7.3 ± 1.3 | 2.0 ± 0.2 | 5.4 ± 2.5 |
| SBFW | 8.6 ± 0.8 | 6.2 ± 1.0 | 15.7 ± 2.9 |
| UOSBFT | 3.5 ± 0.2 | 2.0 ± 0.3 | 4.3 ± 1.9 |
SBFT: suture-bridge FiberTape; SBFW: suture-bridge FiberWire; UOSBFT: under-over suture-bridge FiberTape.
Anterior and posterior translation
Both the UOSBFT and SBFT techniques yielded significantly less translation for anterior translation (2.0 ± 0.2 and 2.0 ± 0.3, respectively) compared to the SBFW group (6.2 ± 1.0) (P = .005 and P = .007, respectively) (Figure 6) (Table 2).
Figure 6.
Mean (SEM) anterior translation testing values for three variations of a novel independent AC ligament reconstruction at loads of 10, 20 and 30 N. SBFT: suture-bridge FiberTape; SBFW: suture-bridge FiberWire; UOSBFT: under-over suture-bridge FiberTape.
Similar results were yielded for posterior translation, with the UOSBFT (4.3 ± 1.9) and SBFT (5.4 ± 2.5) repairs translated less than the SBFW repair (15.7 ± 2.9) (P = .023 and P = .033, respectively) (Figure 7) (Table 2).
Figure 7.
Mean (SEM) posterior translation testing values for three variations of a novel independent AC ligament reconstruction at loads of 10, 20 and 30 N. SBFT: suture-bridge FiberTape; SBFW: suture-bridge FiberWire; UOSBFT: under-over suture-bridge FiberTape.
For both anterior and posterior translation, there was no statistical difference between SBFT and UOSBFT. Every 10 N increase in load leads to a significant increase in anterior translation for all three repair techniques (P < .001); however, posterior translation was not significantly affected by increasing load.
Cross-over design
It was found that in the specimens of the SBFT repair that underwent anterior–posterior translation first, the results of the subsequent superior translation testing were significantly affected (P = .01) when compared to the specimens that first underwent SI testing followed by AP. For both the SBFW and UOSBFT repairs, there was no significant difference between the results of those specimens tested in AP first followed by SI and those specimens of the same repair group tested in SI first followed by AP.
Pull to failure
The ultimate failure loads of both the SBFT and SBFW repairs were 1.5 times greater than that of the UOSBFT repair (P = .03 and P = .02, respectively) (Figure 8(a)) (Table 3). Repair SBFW had a significantly higher total energy to failure compared to the UOSBFT repair (P = .01) (Figure 8(b)) (Table 3). There was no statistical difference between the stiffness of the three groups. The mode of failure during load to failure testing was distal clavicle fracture in 18 specimens, anchor pull-out in 5 specimens and spine of the acromion fracture in 1 specimen.
Figure 8.
Pull to failure testing – comparison of (a) ultimate failure load, (b) total energy and (c) stiffness for three groups of a novel AC ligament reconstruction. SBFT: suture-bridge FiberTape; SBFW: suture-bridge FiberWire; UOSBFT: under-over suture-bridge FiberTape.
Table 3.
Pull to failure (mean ± SEM).
| Reconstruction type | Ultimate failure l oad (N) | Total energy (N m) | Stiffness (N/mm) |
|---|---|---|---|
| SBFT | 174.6 ± 10.8 | 3.6 ± 0.6 | 7.3 ± 0.3 |
| SBFW | 172.3 ± 6.2 | 3.6 ± 0.3 | 6.5 ± 0.2 |
| UOSBFT | 128.9 ± 14.8 | 2.5 ± 0.3 | 8.3 ± 1.1 |
SBFT: suture-bridge FiberTape; SBFW: suture-bridge FiberWire; UOSBFT: under-over suture-bridge FiberTape.
Discussion
The ideal surgical construct for AC joint dislocations would be a repair that minimises both horizontal and vertical translation of the clavicle to the greatest degree when under stress, coupled with limited additional complications. In this study, we endeavoured to determine whether a construct, which repaired the AC ligament alone, ignoring the routinely repaired CC ligaments, would provide the minimal joint translation required for a strong intra-operative construct. The results of this study indicate that minimal joint translation can be achieved with a construct repairing the AC ligament alone.
The UOSBFT repair yielded the least translation in all directions of testing (superior, anterior and posterior) (Table 2). The greatest benefit of this construct was seen in the superior plane, which showed a two-fold decrease in translation from the other two groups (P < .05). Both the techniques utilising FiberTape resulted in significantly less translation in the anterior and posterior planes compared to the SBFW repair. This reduced translation may potentially be attributed to the increased thickness and thus strength of the FiberTape material. Although the UOSBT repair was more resistant to translation, it yielded a lower load to failure compared to the other two repair groups, the reason of which we are uncertain.
A study by Costic et al.14 evaluating the translation of the native intact AC ligaments at a load of 70 N resulted in 5.0 ± 0.9 mm of anterior translation, 6.6 ± 2.5 mm of posterior translation and 3.6 ± 1.6 mm of superior translation, results of which are comparable to both the translational results of the SBFT (superior: 7.3 ± 1.3, anterior: 2.0 ± 0.2, posterior: 5.4 ± 2.5) and UOSBFT (superior: 3.5 ± 0.2, anterior: 2.0 ± 0.3, posterior: 4.3 ± 1.9) repair groups. Although our study tested translation at loads of 10, 20 and 30 N, the analogous results give an indication of the strength of this novel construct in its ability to maintain ample joint stability.
The suture-bridge configuration that this technique is centred around is perhaps the foundation for the stability of this novel construct. The cross arrangement at the centre of the configuration allows for the distribution of force across the width of the joint margin and, coupled with the lateral struts that function as side restraints, combine to limit AP translation. The strength of this configuration was verified in the minimal anterior and posterior translation observed in the SBFT and UOSBFT repair groups. The modification of the suture-bridge in the UOSBFT repair group, with the lateral struts positioned on the inferior aspect of the joint, is perhaps the basis for the decreased superior translation achieved, as the altered configuration creates a compressive tension in the vertical plane of the joint. In addition, the relatively close fixation points of the configuration allow for greater tension and thus stability.
Biomechanically, the AC ligaments have consistently been shown as essential for horizontal stability.5,7,8 A study by Dawson et al.9 showed that the AC ligaments contribute 90% more anterior–posterior stability than the CC ligaments. Moreover, instability in the horizontal plane has been associated with inferior clinical outcomes. This hypothesis is supported by a study by Tauber et al.,11 wherein the authors noted a distinct correlation between patients suffering from persistent horizontal AC joint instability and lower outcomes according to AC joint specific clinical scores. Thus, a strong AC ligament construction, preventing anterior–posterior translation, would potentially improve clinical results.
Surgical techniques ignored reconstruction of the AC ligaments due to the common understanding that the superior AC ligament runs straight across the superior joint surface, as described in anatomical text books. This anatomical orientation of the AC ligament would thus render surgical reconstruction of the ligament useless in preventing horizontal instability15 due to the ligament’s perpendicular alignment to the force vector. However, a recent anatomical study by Nakazawa et al. examining the orientation and variation of the AC ligaments in cadaveric shoulders refuted this previous understanding of the AC ligament anatomy, finding that the superior AC ligament was in fact orientated obliquely, running from the antero-superior part of the acromion and attaching onto the infero-posterior part of the distal clavicle (Figure 9).1 This newly understood ligamentous structure was consequently adapted into the design of our reconstruction with the anterior component of the suture-bridge, somewhat mimicking the described orientation of the superior AC ligament. The more anatomical reconstruction of the native AC ligament may have added to the increased horizontal stability achieved in our novel construct.
Figure 9.
The orientation of the AC ligament from a superior view. (a) The previous anatomical description of the ligament and (b) the ligament orientation based on the study by Nakazawa et al.1 Cl: clavicle; Lat: lateral; Post: posterior; SS: scapular spine.
To the best of our knowledge, most of the previous biomechanical studies that evaluated different repair techniques for ACJ instability utilised a cadaveric model for testing. A study by Beitzel et al.16 comparing a number of different AC ligament repairs combined with a standard CC ligament repair in a cadaveric model showed comparable, if not increased superior translation, compared to our independent AC ligament repair technique, despite the additional CC ligament repair utilised in their construct. Thus, based on our results, a repair constructing the AC ligaments alone has the potential to create a construct that mimics the stability of a technique repairing both the AC and CC ligaments. A construct, ignoring reconstruction of the CC ligaments, has the added advantage of a potentially less invasive procedure, as well as preventing the complications often associated with CC ligament repairs, such as hardware failures.12
There are several limitations of this study that must be considered. First, the Sawbones model utilised is devoid of the static stabilisers of the AC joint as well as the dynamic stabilisers of the shoulder joint. Although this allowed for pure translational and ‘load to failure’ testing of the construct alone, we were not able to gain a complete understanding of the stability of this construct in an anatomically functioning joint. Second, the in vitro nature of biomechanical studies means that when applied clinically the construct may function differently. This is particularly in relation to the complex nature of the forces on the AC joint and also the movement of the joint in different shoulder movements. Third, the anatomy of the human AC joint and surrounding structures is far more complex than that of the Sawbones model. Thus, clinically, surgical reconstruction may not be reproducible in the same way as tested on the Sawbones model. Anchor positioning in the distal clavicle as well as drill holes into the acromion may differ, as the soft tissue structures in the human shoulder may limit accurate positioning and may also require altered surgical technique for appropriate execution. Further clinical studies are thus required in order to critically assess the outcomes of this novel technique in patients with ACJ separations, prior to its recommendation for use.
Conclusion
In summary, this study is the first to evaluate the biomechanical properties of a novel independent AC ligament repair technique, disregarding the routinely reconstructed CC ligaments, for ACJ reconstruction. The construct demonstrated significant translational stability in both the anterior–posterior and superior–inferior planes of testing when placed under mechanical stress, restoring stability to a state comparable to the native ligaments of the intact joint without repair of the CC ligaments.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Ethical Review and Patient Consent
This is a controlled laboratory experiment using synthetic Sawbones only, thus no IRB approval required.
References
- 1.Nakazawa M, Nimura A, Mochizuki T, et al. The orientation and variation of the acromioclavicular ligament: an anatomic study. Am J Sports Med 2016; 44: 2690–2695. [DOI] [PubMed] [Google Scholar]
- 2.Epstein D, Day M, Rokito A. Current concepts in the surgical management of acromioclavicular joint injuries. Bull NYU Hosp Jt Dis 2012; 70: 11–24. [PubMed] [Google Scholar]
- 3.Virtanen V, Tulikoura I, Remes V, et al. Surgical treatment of chronic acromioclavicular joint dislocation with autogenous tendon grafts. SpringerPlus 2014; 3: 420–420. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Lemos MJ. The evaluation and treatment of the injured acromioclavicular joint in athletes. Am J Sports Med 1998; 26: 137–144. [DOI] [PubMed] [Google Scholar]
- 5.Mazzocca AD, Arciero RA, Bicos J. Evaluation and treatment of acromioclavicular joint injuries. Am J Sports Med 2007; 35: 316–329. [DOI] [PubMed] [Google Scholar]
- 6.Debski RE, Parsons IM 4th, Woo SL, et al. Effect of capsular injury on acromioclavicular joint mechanics. J Bone Joint Surg Am 2001; 83: 1344–1351. [DOI] [PubMed] [Google Scholar]
- 7.Klimkiewicz JJ, Williams GR, Sher JS, et al. The acromioclavicular capsule as a restraint to posterior translation of the clavicle: a biomechanical analysis. J Shoulder Elbow Surg 1999; 8: 119–124. [DOI] [PubMed] [Google Scholar]
- 8.Lee KW, Debski RE, Chen CH, et al. Functional evaluation of the ligaments at the acromioclavicular joint during anteroposterior and superoinferior translation. Am J Sports Med 1997; 25: 858–862. [DOI] [PubMed] [Google Scholar]
- 9.Dawson PA, Adamson G, Pink M, et al. Relative contribution of acromioclavicular joint capsule and coracoclavicular ligaments to acromioclavicular stability. J Shoulder Elbow Surg 2009;18: 237–244. [DOI] [PubMed]
- 10.Blazar PE, Iannotti JP, Williams GR. Anteroposterior instability of the distal clavicle after distal clavicle resection. Clin Orthop Relat Res 1998; 348: 114–120. [PubMed] [Google Scholar]
- 11.Tauber M, Valler D, Lichtenberg S, et al. Arthroscopic stabilization of chronic acromioclavicular joint dislocations. Am J Sports Med 2015; 44: 482–489. [DOI] [PubMed] [Google Scholar]
- 12.Clavert P, Meyer A, Boyer P, et al. Complication rates and types of failure after arthroscopic acute acromioclavicular dislocation fixation. Prospective multicenter study of 116 cases. Orthop Traumatol Surg Res 2015; 101: S313–S316. [DOI] [PubMed] [Google Scholar]
- 13.Deshmukh A, Wilson D, Zilberfarb J, et al. Stability of Acromioclavicular Joint Reconstruction. Am J Sports Med 2004; 32: 1492–1498. [DOI] [PubMed]
- 14.Costic RSJ, Jari R, Rodosky M, et al. Joint compression alters the kinematics and loading patterns of the intact capsule-transected AC joint. J Orthop Res 2003; 21: 379–385. [DOI] [PubMed] [Google Scholar]
- 15.Taranu R, Rushton PR, Serrano-Pedraza I, et al. Acromioclavicular joint reconstruction using the LockDown synthetic implant: a study with cadavers. Bone Joint J 2015; 97-B: 1657–1661. [DOI] [PubMed] [Google Scholar]
- 16.Beitzel K, Obopilwe E, Apostolakos J, et al. Rotational and translational stability of different methods for direct acromioclavicular ligament repair in anatomic acromioclavicular joint reconstruction. Am J Sports Med 2014; 42: 2141–2148. [DOI] [PubMed] [Google Scholar]