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Acromioclavicular (AC) joint injuries are extremely common in the athletic population. Although most low-grade injuries can be managed nonoperatively, high-grade injuries often require reconstruction of the AC joint. Various reconstructive options have been described with varying risks and benefits to each. Implant or graft failure with loss of reduction as well as clavicle and coracoid fracture are a few of the more common complications following AC joint reconstruction surgery. Currently, no gold standard exists. This technical paper describes an arthroscopically assisted AC joint reconstruction technique using the Infinity-Lock Button System with hamstring allograft augmentation. This technique provides an anatomic, minimally invasive, low-profile reconstruction that may minimize risk of clavicle and coracoid fracture. It also provides augmented stabilization across the AC joint, which may also help resist naturally occurring horizontal and rotational displacing forces.
See video under supplementary data.
Acromioclavicular (AC) joint injuries are extremely common and represent 30% to 50% of all athletic shoulder injuries.
These injuries range from low-grade, types 1 and 2, which may be managed nonoperatively, to high-grade injuries, types 4, 5, and 6, which typically require surgical reduction and fixation. There is less consensus on the management of type 3 injuries. Most often, initial nonoperative treatment is recommended, although acute reconstruction may be recommended on a case-by-case basis.
The anteroposterior stability of the AC joint is attributable to the AC joint capsule and the 4 AC ligaments, although the majority of horizontal stability is due to the posterior and superior AC ligaments.
Vertical stability is provided by the coracoclavicular (CC) ligaments, the conoid medially, and the trapezoid laterally.
A vast number of implants and techniques have been described for reconstructing the AC joint. These include use of pins, plates, screws, allograft or autograft, all-suture based reconstructions, or transfer of the coracoacromial ligament (modified Weaver–Dunn) and use arthroscopic or open techniques.
In this technical paper, we describe an arthroscopic-assisted AC joint reconstruction using the Infinity-Lock Button System (Xiros, Leeds, UK) with hamstring allograft reinforcement.
Surgical Technique (With Video Illustration)
The patient is placed in the lateral decubitus position (Video 1). General endotracheal anesthesia and a supraclavicular region block are used. An examination under anesthesia is performed, noting the degree of AC joint instability and reducibility. After routine skin preparation and draping, landmarks are marked out. With a ruler, the planned Infinity-Lock drill hole through the clavicle is marked approximately 3 to 4 cm medial to the AC joint.
A standard mid-posterior glenoid viewing portal is established followed by an anterior rotator interval portal. Visualization is accomplished with a 30° arthroscope. With a shaver, the rotator interval tissue is cleared away to identify the coracoid. We then switch to a 70° arthroscope for the remainder of the case. Both the shaver and radiofrequency ablation are used to remove tissue circumferentially around the coracoid to provide visualization. One should be able to see the undersurface of the clavicle and the coracoid tubercle.
A saber incision is made half the distance between the AC joint and the planned clavicular drill hole. The deltotrapezial fascia is taken down in a single layer longitudinally along the clavicle. Care is taken not to strip anteriorly or posteriorly to maintain the arthroscopic space underneath.
A needle is placed in the AC joint for reference. A second needle is placed 3 to 4 cm medial to the AC joint just anterior to the clavicle to verify the drilling trajectory over the anatomic insertion point of the CC ligaments (Fig 1). A 2.4-mm drill pin is placed centrally through the clavicle 3 to 4 cm medial to the AC joint and directed toward to CC ligament origin of the coracoid. A 4.0-mm cannulated drill is passed over the pin drilling through the clavicle. The central drill pin is removed while keeping the drill in the clavicle. A nitinol wire is passed through the drill and shuttled out the rotator interval portal with a retriever. The drill is removed, leaving the nitinol wire in place. A 1-cm fascial incision is made anterior to the clavicle adjacent to the drill hole. The nitinol wire loop exiting out the anterior portal is retrieved through the fascial split.
The coracoid passer is placed through the fascial incision into the space between the clavicle and coracoid. The tip of the passer slides along the medial edge of the coracoid inferiorly coming around the base laterally (Fig 2). The tails of a second nitinol wire are placed through the passer and retrieved through the anterior clavicular fascial incision with a grasper. The coracoid passer is removed, leaving the nitinol wire around the base of the coracoid with the looped end on the medial side.
The hamstring graft may be prepared at any point. It should be whip-stitched at both ends using nonabsorbable suture. The green lead ETHIBOND suture (Ethicon, Somerville, NJ) of the Infinity-Lock is loaded into the loop of the nitinol wire around the coracoid. The Infinity-Lock is then partially shuttled from medial to lateral around the coracoid. Before it is pulled completely around the coracoid, a lead hamstring suture is placed through the ETHIBOND lead suture just in front of the Infinity-Lock implant. Both are then completely shuttled. Both should move freely around the coracoid. The tails of the Infinity-Lock are loaded through the concave portion of the loop of the device and the green lead suture is removed (Fig 3). The tails are tensioned to synch the device around the coracoid. Toggling the tails helps remove any laxity. Direct palpation through the fascia as well as arthroscopic viewing allows confirmation the Infinity-Lock is secured around the coracoid.
The tails of the device are loaded through the remaining nitinol wire loop. The tails are then shuttled through the clavicle from inferior to superior. The tails are loaded through the center 2 holes of the Infinity-Lock button, which is approximated to the clavicle. Next, the coracoid passer with nitinol wire is placed from posterior to anterior underneath the clavicle. This allows shuttling of a single tail of the Infinity-Lock device along with the hamstring lead suture traversing up from the medial side of the coracoid. Incompletely shuttle the Infinity-Lock limb to leave a loop anteriorly (Fig 4). The 2 tails are tensioned to reduce the AC joint. A half hitch is tied. While maintaining tension, the posteriorly passed limb is completely shuttled and the knot stack is completed on the posterior surface of the clavicle. The hamstring tails are tied in a half hitch and tensioned to match the Infinity-Lock construct (Fig 5). Interrupted #2 nonabsorbable sutures are placed into the hamstring half-hitch to secure the graft. The tails of the graft are brought over the top laterally and sewn into the periosteum to reinforce the AC joint. The deltotrapezial fascia is closed followed by a standard skin closure.
Following the procedure, the patient is immediately placed in a sling with an abduction and derotational pillow (Table 1). For the first 6 weeks, the patient remains in the sling at all times except to perform elbow, wrist, and hand range-of-motion exercises. After 6 weeks, the sling is discontinued and active-assist shoulder range of motion is started with a physical therapist. Starting at 8 weeks postoperatively, isometric rotator cuff strengthening is started and progressed as tolerated. Sports-specific training commences at 16 weeks postoperatively, and patients are permitted to return to full activity at 24 weeks.
Table 1Postoperative Protocol After Arthroscopic-Assisted Acromioclavicular Joint Reconstruction Using Infinity-Lock Button System With Hamstring Allograft Augmentation
Patient is immobilized in a sling with an abduction and derotation pillow.
Use of the sling and pillow continues; elbow, wrist, and hand range-of-motion exercises are permitted.
Use of the sling is discontinued; active-assisted range of motion is begun.
Isometric rotator cuff strengthening is started and progressed as tolerated.
Options for AC joint reconstruction are varied, and no current gold-standard exists. A recent meta-analysis and systematic review found the overall failure rate for AC joint reconstruction to be around 20%.
There were no significant differences in failure rates between the majority of the surgical techniques. Anatomic reconstructions have, however, been shown to have improved failure rates over the nonanatomic Weaver–Dunn procedure.
A database study showed similar results with a reoperation rate of 1.6% for irrigation and debridement, 4.2% for revision reconstruction, and 6.2% for hardware removal all within the first 6 months of surgery.
found that combining allograft loop fixation with suture button fixation yielded a significantly lower failure rate than allograft fixation alone.
Repair of the AC joint capsule is also not without debate. Yet, some biomechanical studies indicate that repair of the capsule with CC ligament reconstruction most closely restores resistance to normally experienced translational and rotational forces.
The Infinity-Lock Button System has not been evaluated against other reconstruction techniques. However, this technique theoretically helps minimize fracture risk, as there is no drill hole in the coracoid and only a single drill hole in the clavicle (Table 2). Augmentation with hamstring allograft helps increase the stability of the repair and may help further mitigate fracture risk by decreasing the stress riser from the implant. The resulting fixation is low profile and decreases the chance of irritation from bulkier fixation methods. In addition, laying the tails across the AC joint and suturing them to the periosteum may provide additional stability across the AC joint. This technique is fairly minimally invasive and use of the arthroscope assists in anatomic graft and implant placement around the base of the coracoid.
Overall, this technique provides an arthroscopically assisted anatomic reconstruction of the CC ligament through a minimally invasive incision with minimal implant bulk, decreasing the risk of irritation of the construct. Risk of fracture is minimized and additional stability is provided via augmentation of the AC joint.
This video demonstrates the technique of an arthroscopically assisted acromioclavicular joint reconstruction using the Suture-Lock Button System (Xiros, Leeds, UK) with hamstring allograft augmentation. This is a left shoulder with the patient positioned in the lateral decubitus position. The majority of the procedure is performed using a 70° arthroscope viewing from the posterior portal and working through an anterior rotator interval portal as well as a small saber incision 2 cm lateral to the acromioclavicular joint.
The authors report the following potential conflicts of interest or sources of funding: R.M.F. reports personal fees from Arthrex and Elsevier, outside the submitted work. S.W.T. reports nonfinancial support from Xiros, Leeds, UK , during the conduct of the study; personal fees and other from Smith & Nephew, outside the submitted work; and Exactech, consultant; Xiros, consultant; and MinInvasive, consultant. Full ICMJE author disclosure forms are available for this article online, as supplementary material.