The biological response to a failed extra-articular polyester ligament used for AC Joint reconstruction at the shoulder girdle: a retrieval analysis of five cases

Kinematic and Radiographic Evaluation of Acromioclavicular Reconstruction with a Synthetic Ligament

Purpose

The optimal surgical technique for unstable acromioclavicular (AC) and coracoclavicular (CC) joint injuries has not yet been established. The biomechanical and radiographic effect of the LockDown device, a synthetic ligament for AC joint reconstruction, was evaluated to assess the optimal surgical technique for unstable AC and CC joint injuries. It was hypothesized that the LockDown device would restore AC joint kinematics and radiographic stability to near native values.

Methods

Three fresh frozen cadaveric torsos (6 shoulders) modelled CC joint motion in their "native," "severed," and "reconstructed" states. The effects of stressed and unstressed native, severed, and reconstructed conditions on AC separation and CC distances in anteroposterior, mediolateral, and inferosuperior directions during shoulder abduction, flexion, and scaption were assessed. The analysis of variance (p, 0.05) was used to compare CC distance and peak AC distance in anteroposterior, mediolateral, and inferosuperior directions during shoulder flexion, abduction, and scaption measurements among native, severed, and reconstructed states with unstressed and stressed Zanca radiographic views.

Results

From radiographic analyses, the CC distance was significantly greater (p=0.001) across the surgical state in stressed versus unstressed views. Mean difference between stressed and unstressed views was 1.8 mm in native state, 4.1 mm in severed state, and 0.9 mm in reconstructed state. The CC distance was significantly greater in the "severed" state (10.4 mm unstressed; 14.5 mm stressed) compared to the "native" state (p=0.016) (6.5 mm unstressed; 8.3 mm stressed) and compared to the "reconstructed" state (p=0.005) (3.1 mm unstressed; 4.0 mm stressed) and significantly less (p=0.008) in the "reconstructed" state compared to the "native" state. CC distances decreased from native to reconstructed, an average of 3.3 mm for unstressed and 4.3 mm for stressed. On average, peak AC joint separation distance in anteroposterior, mediolateral, and inferosuperior directions during shoulder-abduction, flexion, and scaption was shown to be restored to 11.5 mm of native values after reconstruction with LockDown device.

Conclusion

Reconstruction of AC joint with LockDown synthetic ligament restores motion of clavicle and acromion to near native values, thereby decreasing scapular dyskinesis and enhancing AC joint stability.

Anatomic reconstruction of acromioclavicular joint dislocations using allograft and synthetic ligament

Background

Acromioclavicular (AC) separations are commonly seen shoulder injuries. Numerous surgical reconstruction techniques have been described. In this study, we present a series of patients who underwent an anatomic reconstruction using a synthetic ligament and allograft construct.

Methods

We performed a retrospective review of patients with type IV or V AC separations who underwent primary or revision AC reconstruction with a luggage-tag synthetic ligament and a semitendinosus allograft placed through the anatomic insertion sites of the coracoclavicular ligaments. Patient-reported outcomes, as well as complication rates, were recorded at a minimum 2-year follow-up.

Results

Ten patients with a mean age of 44.2 ± 14.9 years were included in the study. The mean Disabilities of the Arm, Shoulder and Hand score was 15.5 ± 15.4; mean Single Assessment Numeric Evaluation score, 81.8 ± 12.1; mean Simple Shoulder Test score, 11.4 ± 1.1; mean American Shoulder and Elbow Surgeons score, 84.6 ± 15.7; mean Constant score, 82.5 ± 11.6; and mean visual analog scale score, 2 ± 2.6.

Conclusion

The technique using a luggage-tag synthetic ligament along with an anatomic allograft coracoclavicular ligament reconstruction is a safe, effective alternative to other techniques described in the literature.

Synthetic coracoclavicular ligament vs. coracoclavicular suspensory construct for treatment of acromioclavicular dislocation: a biomechanical study

BACKGROUND

A synthetic ligament (LockDown, Worcestershire, England) has become available to treat complete acromioclavicular dislocation with promising clinical results and potential benefit to avoid postoperative loss of reduction. We investigated the biomechanics of this synthetic ligament in a simulated immediate postoperative rehabilitation setting, hypothesizing that the synthetic ligament would demonstrate less superior coracoclavicular displacement to cyclic loading and higher ultimate load-to-failure values than a coracoclavicular suspensory construct.

METHODS

Seven matched-pair cadaveric shoulders (mean age at time of death, 79 years) were loaded cyclically and to failure. One specimen in each pair was randomly assigned to the synthetic ligament or coracoclavicular suspensory construct. Superiorly directed 70-N cyclic loading for 3000 cycles at 1.0 Hz was applied through the clavicle in a fixed scapula simulating physiologic states during immediate postoperative rehabilitation, followed by a load-to-failure test at 120 mm/min.

RESULTS

After 3000 cycles, the superior displacement of the clavicle in the synthetic ligament (9.2 ± 1.1 mm) was 225% greater than in the coracoclavicular suspensory construct (2.8 ± 0.4 mm, 95% confidence interval [CI] 3.4, 8.3; P < .001). Average stiffness of the synthetic ligament (32.8 N/mm) was 60% lower than that of the coracoclavicular suspensory construct (81.9 N/mm, 95% CI 43.3, 54.9; P < .001). Ultimate load-to-failure of the synthetic ligament was 23% (95% CI 37.9, 301.5; P = .016) lower than the coracoclavicular suspensory construct (580.5 ± 85.1 N and 750.2 ± 135.5 N, respectively).

CONCLUSION

In a simulated immediate postoperative cadaveric model, the synthetic ligament demonstrated poorer biomechanics than the coracoclavicular suspensory construct. These findings suggest that a coracoclavicular suspensory construct may be preferable to a synthetic ligament if early rehabilitation is intended.

Radiographic appearance of the distal clavicle in relation to the acromion after acromioclavicular joint reconstruction using a braided polyester mesh

ACJ stabilization using a braided polyester mesh has become popular in ACJ injuries. However, concerns have been raised about excessive anterior clavicle displacement. The purpose of this study was to report radiographic position of the distal clavicle in relation to the acromion after ACJ reconstruction using this device immediately postoperative and after 6 months follow-up compared with a healthy control group. Thirty-eight patients with ACJ instability treated with a braided polyester mesh were compared within group (pre-/postoperatively) and between groups (with age/sex matched controls). Biplane radiographic measurements by 2 observers were made preoperatively, immediate postoperatively and at 6 months follow-up. Inter-observer reliability was assessed and clinical outcome scores were recorded. ACJ stabilization significantly reduced vertical displacement immediately postoperatively (13.8 ± 4.2 to 3.5 ± 5.5 mm; p < 0.0001) towards controls (1.7 ± 2.3 mm,p < 0.0873). Slight further superior displacement (4.4 mm) occurred at 6 months follow-up compared to immediately postoperative (p = 0.0029) and 6.2 mm more than mean controls (p < 0.0001). In the axial plane, significant early reduction of posterior displacement was achieved (10.3 ± 8.0 to 1.1 ± 5.1 mm,p = 0.0240) and the clavicle settled back to a more posterior position at 4.5 ± 6.7  mm at 6 months post-surgery (p = 0.3062). At both time points, posterior displacement was comparable with the controls (3.4 ± 3.0 mm,p = 0.4371 postoperative, p = 0.563 at 6 months follow-up). Excessive anterior displacement has been observed in 2 of the 5 available axial radiographs early postoperative and in 4 of 14 available axial radiographs at 6 months. Constant, Oxford Shoulder and Nottingham Clavicle scores significantly improved (25 ± 12 to 43 ± 7:p < 0.0001, 46 ± 27 to 80 ± 19:p = 0.0038, 53 ± 14 to 80 ± 17:p < 0.0001). ACJ stabilization using a braided polyester device in ACJ instability is effective at reducing both superior and posterior clavicle displacement with excellent clinical outcome. Overcorrection in the axial plane seems to occur, however this is of no clinical and radiographic significance. Posterior displacement is significantly reduced towards control values at 6 months follow-up.

BiPOD Arthroscopic Acromioclavicular Repair Restores Bidirectional Stability

Stabilizing the acromioclavicular joint in the vertical and horizontal planes is challenging, and most current techniques do not reliably achieve this goal. The BiPOD repair is an arthroscopically assisted procedure performed with image intensifier guidance that reconstructs the coracoclavicular ligaments as well as the acromioclavicular ligaments to achieve bidirectional stability. Repair is achieved with a combination of 2-mm FiberTape (Arthrex, Naples, Florida) and 20-mm Poly-Tape (Neoligaments, Leeds, England) to achieve rigid repair, prevent bone abrasion, and promote tissue ingrowth. This study is a prospective review of the first 6 patients treated for high-grade acute acromioclavicular injury with the BiPOD technique. The study included 6 men who were 21 to 36 years old (mean, 27 years). At 6-month follow-up, complications were recorded and radiographic analysis was used to determine the coracoclavicular distance for vertical reduction and the amount of acromioclavicular translation on the Alexander axillary view was used to determine horizontal reduction. One patient had a superficial infection over the tape knot. The difference in coracoclavicular distance between the operated side and the uninvolved side was 9±2 mm preoperatively and 0.3±2 mm at 6-month follow-up. On Alexander axillary view, all 6 patients showed stable reduction, which is defined as a clavicle that is in line with the acromion. The findings show that BiPOD acromioclavicular reconstruction restores bidirectional stability of the acromioclavicular joint at 6 months. [Orthopedics. 2017; 40(1):e35-e43.].

Sternoclavicular joint dislocation and its management: A review of the literature

Dislocations of the sternoclavicular joint (SCJ) occur with relative infrequency and can be classified into anterior and posterior dislocation, with the former being more common. The SCJ is inherently unstable due to its lack of articular contact and therefore relies on stability from surrounding ligamentous structures, such as the costoclavicular, interclavicular and capsular ligaments. The posterior capsule has been shown in several studies to be the most important structure in determining stability irrespective of the direction of injury. Posterior dislocation of the SCJ can be associated with life threatening complications such as neurovascular, tracheal and oesophageal injuries. Due to the high mortality associated with such complications, these injuries need to be recognised acutely and managed promptly. Investigations such as X-ray imaging are poor at delineating anatomy at the level of the mediastinum and therefore CT imaging has become the investigation of choice. Due to its rarity, the current guidance on how to manage acute and chronic dislocations is debatable. This analysis of historical and recent literature aims to determine guidance on current thinking regarding SCJ instability, including the use of the Stanmore triangle. The described methods of reduction for both anterior and posterior dislocations and the various surgical reconstructive techniques are also discussed.