Traumatic disorders of the acromioclavicular joint
According to Tamaoki et al., “the available evidence for treating acute acromioclavicular (AC) dislocations is of poor quality” and “further research exploring the comparison between surgical versus conservative for treating AC dislocation is justified.”
However, operative treatment is mostly preferred and recommended for acute high-grade bidirectional acromioclavicular joint (ACJ) instabilities (Rockwood type IV to VI dislocations), while the optimal type of treatment for grade III ACJ separations remains a topic of heated debate, and the decision whether surgery is indicated should be individually based on the patient’s functional requirements ( Table 23.1 ). A treatment algorithm defined by the International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine (ISAKOS) Upper Extremity Committee suggests to initially treat such injuries nonoperatively with reexamination in 3 to 6 weeks from the date of injury. In cases of bidirectional instability (type IIIb injury), surgical management should be considered.
|Rockwood type||CC Difference||Clavicle Displacement||AC Ligaments||CC Ligaments||Deltoid and Trapezius|
|I||<10%||None or superior||Sprain||Intact||Intact|
|IV||Posterior displacement of the clavicle||Disruption||Disruption||Possible detachment|
|VI||Inferior displacement of the clavicle||Disruption||Disruption||Detachment|
The question of when the capsuloligamentous structures lose their potential to heal has not been answered. A recent systematic review that analyzed early versus delayed surgery recognized that “there is a lack of research to support an optimal time point for surgical intervention in ACJ dislocations”; only four retrospective studies (level III evidence), using different surgical techniques, suggested that early repair may be benefical. The terms “acute” and “chronic” within the context of the timing of surgery therefore remain poorly defined. However, some authors consider ACJ instability as acute, and advocate surgical intervention within 3 weeks from the traumatic injury.
More than 162 reconstructive ACJ procedures have been described in the literature, none of which is considered the current gold standard. Open, single- or two-stage, as well as all-arthroscopic or arthroscopically assisted techniques can be applied. The aim is to reduce the ACJ to enable healing or scarring of the torn ligamentous structures. In the acute situation, static or dynamic, synthetic or biologic coracoclavicular (CC) and/or AC augmentation can be used. A survey conducted among 203 orthopedic facilities in Germany revealed temporary hook-plate retention to be the most frequently applied procedure, followed by a minimally invasive double TightRope (Arthrex) technique. Similar results have been reported by Allemann et al., who conducted a similar survey in Switzerland. These authors also observed that there was a difference in treating ACJ separations depending on the surgeon’s level of training. Foederatio Medicorum Helveticorum board-certified surgeons with or without subspecialization in trauma surgery were more likely to perform hook-plate fixation compared to Foederatio Medicorum Helveticorum or Swiss-equivalent board-certified orthopedic surgeons. Traditional procedures, such as CC screw osteosynthesis or transarticular stabilization using K-wires, currently seem to play a subordinate role.
Minimally invasive techniques appear advantageous for several reasons. General benefits are the reduction of soft tissue trauma, which reduces blood loss, postoperative pain, and risk of infection. , Arthroscopic or arthroscopically assisted techniques also allow concomitant intra-articular lesions to be diagnosed accurately and addressed simultaneously. However, arthroscopic or arthroscopically assisted procedures are, at the same time, considered technically more demanding and may not be suitable for all shoulder surgeons.
Techniques and outcomes
Wolf and Pennington were the first to describe an arthroscopic reconstruction technique for stabilization of acute ACJ separations at the beginning of the new millennium. They reported a procedure using SecureStrand cable (Surgical Dynamics), a suture-like material used in spinal reconstructive procedures, which is pulled through a transclavicular and a coracoidal drill hole and secured anteriorly. The technique was applied in one patient with a type V injury and three patients with type III separations. Similar open techniques have been used previously. In the following years, several other open techniques were modified and executed arthroscopically. , Rolla et al. described an arthroscopic technique using a cannulated screw for CC stabilization after Bosworth suggested this technique as an open procedure. The authors reported excellent preliminary results of nine patients at an average follow-up of 5 months ; however, a second surgery was required to remove the screw 3 months after implantation . Elser et al. described an arthroscopic technique using two or three suture anchors loaded with a FiberWire suture (Arthrex) which are placed in the coracoid process for CC stabilization. The FiberWire sutures are subsequently pulled through transclavicular drill holes and secured over a FASTak suture anchor or Corkscrew (Arthrex), which is placed on the clavicle. The mean Constant score of the 12 patients included was 97 (range, 84 to 100) at 9-month (range, 3 to 18 months) follow-up. Radiographically, anatomic reduction could be achieved in 10 patients; in the remaining two patients, ACJ subluxation (2 to 4 mm) was observed compared to the contralateral side. However, none of these techniques prevailed as the surgical stabilization method of choice.
Richards and Tennet were the first to describe an arthroscopic technique using a pulley-like implant shortly after Hernegger and Kadletz proposed this form of stabilization as an open procedure. This technique requires the implant to be shuttled through a transclavicular and a coracoidal drill hole approximately in the area between the two CC ligaments. The use of pulley-like implants has become increasingly popular, with numerous case series evaluating the results of such techniques. ,
Cohen et al. reported the results of 16 patients with acute ACJ separations (13 with type III and 3 with type IV) treated using an arthroscopic single TightRope technique. At a mean follow-up of 12 months (range, 6 to 18 months), the mean Constant score was 91 (range, 60 to 100); there were two redislocations and loss of reduction in the vertical plane in another three patients (31.3%). El Sallakh et al. reported the results of 10 patients with high-grade bidirectional instabilities similarly treated using an arthroscopic single TightRope technique. At an average of 24 months of follow-up (range, 18 to 30 months), the mean Constant score was 96.3 (range, 94 to 99) and only one (10%) redislocation occurred due to a technical error. Murena et al. reported the results of 16 patients with type III to V ACJ separations who underwent a stabilization using a “double-flip” button device. At an average follow-up of 31 months, the mean Constant score was 97 (range, 82 to 100); a partial loss of reduction due to implant migration was observed in four patients (25%), with a mean (CC) distance of 150% compared to the contralateral side.
Other authors have observed high rates of early failures after using single TightRope implants, led these authors to advocate the use of double bundle devices. , Salzmann et al. reported the outcomes of 23 patients with acute Rockwood type III to V ACJ separations stabilized by the aid of two TightRope devices, which are placed in line with the CC ligaments. At an average follow-up of 30.6 months (± standard deviation [SD] 5.4 months), the mean Constant score was 94.3 (±SD 3.2), Simple Shoulder Test score was 12.0 (±SD 0) and Short Form-36 (physical component) was 56.2 (±SD 3.2) points. The average CC distance measured on bilateral anteroposterior stress views on the affected side was 10.5 mm (±SD 3.6 mm) versus 10.6 mm (±SD 2.5 mm) on the contralateral side. The horizontal component of instability was assessed on the axillary radiograph; there were four isolated posterior displacements and three combined displacements (30.4% recurrent instability rate). A mid-term follow-up study on the same cohort of patients was reported after 58 months (±SD 5.6 months). Clinical results remained satisfying and 17 of 20 radiographs (85%) remained unchanged; one case of overcorrection settled into an anatomic position, and there were two new cases of posterior subluxation. The senior author of this chapter (M.S.) reported the results of 28 patients with acute type V ACJ dislocations that were treated using an arthroscopically assisted double TightRope. At an average follow-up of 26.5 months (range, 20.1 to 32.8 months), a mean subjective shoulder value (SSV) of 95% (range, 85 to 100), Constant score of 89 (range, 52 to 100), Taft score of 10 (range, 5 to 12), and Acromioclavicular Joint Instability score of 79.9 (range, 45 to 100) was reported. The mean CC distance at the final follow-up was 13.6 mm (range, 5 to 27 mm) on the affected side and 9.4 mm (range, 4 to 15 mm) on the contralateral side. Signs of posterior instability on bilateral Alexander views were noted in 42.9% of all cases; such patients displayed significantly inferior results in the Taft and Acromioclavicular Joint Instability scores. For these specialized views, stress on the ACJ is exaggerated by the patients placing the ipsilateral arm in the cross-body position. The radiographs are taken according to a Y view in a 45-degree angle to the detector. The contralateral unaffected side serves as a control.
Although research efforts have increased our understanding of the horizontal component of ACJ instability during the last decade, only a few authors have reported the results of combined CC/AC stabilization procedures. Li et al. described an arthroscopically assisted technique using a double endobutton device for CC and a suture anchor (FASTIN RC, Depuy Mitek) for AC stabilization; this anchor is screwed into the distal clavicle approximately 0.5 cm medial to the ACJ. Additionally, four drill holes are required in the acromion; the sutures of the anchor are then divided into two groups, which are then pulled from superior to inferior through the medial drill holes of the acromion and shuttled back from inferior to superior via the lateral holes, and lastly passed through a transclavicular drill hole and securely tied ( Fig. 23.1 ). The authors reported the results of 10 patients affected by bidirectional high-grade ACJ separations. At a mean follow-up of 33.6 months (±SD 5.4 months), the mean Constant scores improved from 25.2 (±SD 6.6) preoperatively to 92.4 (±SD 6.5) postoperatively, while the mean VAS score decreased from 5.9 (±SD 1.4) to 1.2 (±SD 0.9); however, unfortunately, no radiographic results were reported. De Beer et al. described the BiPOD technique using a combination of FiberTape (Arthrex) and PolyTape (Neoligaments) for bidirectional ACJ stabilization. Two transclavicular drill holes, which are placed in line with the former CC ligaments, and one transacromial drill hole need to be established for this procedure. The FiberTape and the PolyTape are passed through these tunnels and underneath the coracoid process ( Fig. 23.2 ). The authors reported the preliminary results (i.e., average follow-up of 6 months) in six patients with acute high-grade ACJ separations that were managed using this technique. The mean CC difference was 0.3 mm (±SD 2 mm), and there were no signs of horizontal instability noted on bilateral Alexander views. Banffy et al., on the other hand, described a technique using a SutureTape (Arthrex) and a semitendinosus allograft for CC stabilization and a SutureTak (Arthrex) for additional AC stabilization. The authors reported the results of 17 patients with type III to V ACJ separations. At a mean follow-up of 29 months (±SD 9 months) the mean American Shoulder and Elbow score was 91.1 (±SD 6.7) and the Single Assessment Numeric Evaluation score was 91.1 (±SD 6.7) points. The mean CC distance was 30.0 mm (±SD 3.1 mm); horizontal stability was not evaluated.
We recently reported the surgical (i.e., arthroscopic-assisted) results of 34 patients with type V injuries using a double TightRope device and an additional FiberTape Cerclage, which is shuttled through a transclavicular hole, then through a transacromial hole and finally back to clavicle. At a mean follow-up of 26 months (range, 20 to 61 months) the mean CC distance was 12.1 mm (range, 6.5 to 19.5 mm) on the operated side and 10.0 mm (range, 2 to 17 mm) on the contralateral side. Horizontal stability was assessed by the aid of bilateral Alexander views ( Fig. 23.3 ); complete dynamic posterior translation (DPT) was present in 2 (5.9%) and partial DPT in 14 (41.2%) patients. The mean SSV was 90% (range, 25% to 100%), Constant score was 90 (range, 33 to 100), Taft score was 11 (range, 4 to 12), and the Acromioclavicular Joint Instability score was 87 (range, 43 to 100) points. Inferior radiographic results were not necessarily accompanied by inferior clinical outcomes.
Although there is a lack of high-level evidence to support the value of additional AC stabilization, surgical results appear beneficial thus far. A recent study performed at our institution that evaluated 104 patients after arthroscopically assisted stabilization of acute high-grade ACJ separations determined that the use of an additional AC cerclage is advantageous. Patients who underwent CC stabilization alone were significantly more likely to develop complete DPT compared to patients who underwent combined CC/AC stabilization. Overreducing the ACJ was found to be likewise benefical. High CC distances and DPT were also found to be associated with worse clinical results (i.e., higher pain scores). The timing of surgery, ossifications of the CC ligaments, age, and body habitus did not influence radiographic results. A similar study was conducted by the French Society for Arthroscopy evaluating 116 patients with type III to V ACJ separations managed using various surgical techniques. They similarly found that AC stabilization was associated with improved horizontal stability. The use of a biological tissue graft was likewise beneficial. The authors also observed that high body mass index values were associated with a high ratio of CC distances between the injured and uninjured side, as well as an increased distance between the anterior cortical margins of the acromion and distal clavicle on axillary views. Poor radiographic outcome was also found to be accompanied by worse clinical results. The mean ratio of CC distances between the injured and uninjured side was associated with worse Constant scores. Likewise the distance from the anterior edge of the acromion to the anterior edge of the clavicle was found to be associated with higher pain scores and lower Quick Disability of Arm, Shoulder, and Hand score values.
Woodmass et al. conducted a review on complications following arthroscopic stabilization of ACJ separations. The authors evaluated 12 retrospective studies and found CC calcification, infection, fractures, loss of reduction, and persisting pain to be the most commonly observed complications. CC calcification was observed with a pooled rate of 31.6% (95% confidence interval [CI], 10.1% to 58.4%; I 2 = 85.1%). However, significantly lower (i.e., improved) CC distances were observed in patients with severe calcification. Only superficial infections were observed in their study with a pooled rate of 3.8% (95% CI, 0.9% to 8.5%; I 2 = 35.4%). The pooled rate of fractures was 5.3% (95% CI, 2.5% to 9.1%; I 2 = 6.2%). Only one clavicle fracture was reported and attributed to multiple clavicular drill attempts during implant positioning. Fractures of the coracoid were more common and occurred in both single and double tunnel techniques, as well as in patients following coracoid loop fixation. Loss of reduction occurred with a pooled rate of 26.8% (95% CI, 15.5% to 40.0%; I 2 = 73.3%). The pooled rate of persisting pain was 26.7% (95% CI, 17.8% to 36.6%; I 2 = 57.2%), whereby hardware irritation was the most commonly identified source of persisting pain. Recent modifications of the surgical technique using pulley-like implants utilize low-profile devices to not only minimize the risk of suture knot and hardware irritation but also tunnel widening ( Figs. 23.4 and 23.5 ). ,
Authors’ preferred technique
Low-profile ACJ reconstruction, as recently described by Minkus et al., is indicated in acute bidirectional ACJ separations (types IIIb to V according to Rockwood).
The patient is placed in a beach chair position with the affected shoulder prepped and draped in a sterile fashion. Standard posterior, lateral, and anteroinferior portals are established in addition to a 2 to 3 cm incision on the top of the clavicle. A diagnostic arthroscopy is performed first; concomitant intra-articular lesions can be detected and treated if necessary.
Next, the arthroscope is introduced through the lateral transtendinous portal, and the subcoracoid bursa and base of the coracoid are dissected with the aid of a shaver introduced via the anteroinferior portal. Next, a drill hole, required for reduction of the ACJ, is established under image intensifier control and by the aid of a drill guide. The marking hook of this drill guide is introduced through the anteroinferior portal and placed under the coracoid process and the drill sleeve is placed approximately 3 cm medial from the ACJ ( Fig. 23.6 A). A 3 mm transclavicular and coracoidal drill hole is then created between the torn CC ligaments using a drill bit with an internal K-wire ( Fig. 23.6 B–C). The superior part of the clavicle is subsequently unicortically overdrilled using a 5.1 mm drill bit ( Fig. 23.6 D–E). The K-wire is then removed and a nitinol suture passing wire inserted into the drill bit and retrieved anteroinferiorly ( Fig. 23.6 F). The drill bit can then be removed.