Background
Acromioclavicular (AC) joint dislocation is a common injury, accounting for approximately 10% of all shoulder girdle injuries in clinical practice [
1]. It occurs more frequently in young, active populations. Treatment of AC joint dislocation is usually according to the Rockwood classification system [
2] and the functional demand of the patient [
3]. Surgical interventions for advanced AC joint injuries are divided into vertical coracoclavicular (CC) reconstruction, horizontal AC reconstruction, or a combination of both axes [
4]; however, there is no evidence of absolute superiority of one technique over another [
3,
5]. Common procedures for vertical CC reconstruction include CC ligament repair, Bosworth screw fixation, and CC ligament augmentation or reconstruction using artificial materials, autograft or allograft, etc. For horizontal AC joint reconstruction, trans-acromial fixation is the major principle, which is accomplished using several modalities, such as Knowles pinning, Kirschner wire pinning using the tension band technique, and hook plate fixation [
6,
7]. Otherwise, arthroscopic-assisted surgery presents an alternative intervention and also has good results [
8‐
10].
The Phemister [
11] or modified Phemister technique [
12‐
14] has gained in popularity due to its low cost, simple modality, and satisfactory clinical outcome for the treatment of acute AC joint dislocation. CC ligament augmentation [
3,
15,
16] with a suture anchor [
13] or Mersilene tape [
17] also provides effective clinical results. However, soft tissue damage and related blood loss, CC ligament calcification, and clavicle osteolysis [
17] have been reported; in addition, involvement of the coracoid process may lead to axillary nerve compromise [
18]. The hook plate, which features a trans-subacromial hook engagement under the bottom of the acromion, is commonly used nowadays due to its advantages of providing high stability of the AC joint and good functional recovery [
19,
20]. However, complications such as subacromial impingement and rotator cuff damage [
21], acromion osteolysis and further acromion fracture [
22,
23], and clavicle fracture following a retained implant [
24] have been reported. The need for a second surgery for implant removal is also a concern for patients and physicians.
The (modified) Phemister technique, CC ligament augmentation, and hook plate fixation are common procedures with good clinical outcomes. Although there exists comparative research regarding these common surgical modalities in terms of postoperative outcome and complications [
25,
26], the treatment options remain under debate and the mid-term clinical effectiveness still need to be addressed. No study has been performed to compare the outcome of the modified Phemister procedure with CC ligament augmentation using Mersilene tape with hook plate fixation. Otherwise, these two procedures are the most common used surgical method in our institution currently. Therefore, we decide to evaluate these two procedures in this series. We hypothesized that the modified Phemister procedure with CC augmentation using Mersilene tape provides similar clinical and radiological outcomes to hook plate fixation in the treatment of acute AC joint dislocation.
Discussion
To the best of our knowledge, this was the first study in which the clinical and radiological outcomes of the modified Phemister procedure with CC ligament augmentation using Mersilene tape and hook plate fixation were compared. We found that the modified Phemister procedure with CC ligament augmentation resulted in similar functional outcomes to hook plate fixation at the 5-year follow-up point; it also yielded fewer acromial complications, and there is no requirement for a second surgery for implant removal, although the surgical duration was longer, the intraoperative blood loss higher, and the proportion of patients with residual AC joint displacement greater. In light of this comprehensive comparison, the modified Phemister technique with CC ligament augmentation could represent a low-cost alternative surgical option for acute AC dislocation.
Acromioclavicular joint dislocation is a common injury and frequently occurs in active young males. In our series, the average patient age was 43.54 years, with a male dominance (accounting for 65.71%). The optimal treatment option for acute AC joint dislocation remains controversial. Various procedures have been described for the treatment of Rockwood type III to type VI AC joint dislocation [
30]. In vertical stability restoration, CC ligament augmentation is one of the mainstays of surgical treatment, with good reported results [
15,
16,
31]. Regarding horizontal stability restoration, the hook plate method is appealing, because it provides a rigid fixation and offers the promise of high-stability AC joint fixation, while also maintaining normal biomechanical rotation between the clavicle and scapula [
32]. The advantages of this modality are rapid stabilization and reliable reduction maintenance [
33]; however, acromial complications and postoperative discomfort are major concerns following the surgery.
In this study, the HK group demonstrated a significantly shorter surgical duration as compared with the PM group. This result was predictable, as during that surgery, we not only established vertical stability, but also horizontal stability of the AC joint, in contrast with other studies [
17,
34]. The HK group also presented with less blood loss as compared with the PM group
\(=delete\). According to a review of the literature, few studies have assessed the intraoperative blood loss in these groups of patients. We postulated that both the higher blood loss and the longer surgical duration in the CC ligament augmentation group resulted from the more extensive anterior deltoid splitting and advanced soft tissue dissection required to allow the curved passer to pass underneath the coracoid process, which is not required in hook plate fixation. However, this low volume of blood loss would not cause major complications in the general population. Regarding neurovascular injury while passing through the coracoid process, no related complications were noted in the present study. However, for patients with multiple trauma or a high anesthesia risk, hook plate fixation might be a better choice due to the shorter durations of anesthesia and surgery.
Cho et al. [
13] reported the outcomes of 74 patients treated using the modified Phemister technique with CC ligament augmentation using a suture anchor for acute AC joint dislocation. After an average follow-up of 12.3 months, the authors reported satisfactory clinical and radiological results. Rather than a suture anchor, we used double-strained Mersilene tape for augmentation of torn CC ligaments, which also yielded effective results. Rolf et al. [
35] conducted a study of 29 patients managed using a modified Phemister procedure and CC ligament augmentation with polydioxanone (PDS), and also reported satisfactory outcomes after 53 months of follow-up. Our surgical method consisted of the modified Phemister procedure to achieve horizontal stability and CC ligament augmentation for vertical stability of the AC joint. The patients in the PM group had acceptable clinical and radiological outcomes after at least 5 years of follow-up.
Kirschner wires are common implants used to fix the AC joint as an augmentation for temporary stability, and good outcomes have been reported [
36]. However, complications such as pin migration or breakage and pin-tract infection are of concern [
36,
37]. In our series, only one patient had migration of Kirschner wires, but this had no influence on CCD maintenance. Hook plate fixation provided a significantly greater stability of the AC joint than was observed in the PM group according to CCDR analysis . There were 15 cases of residual subluxation in the PM group (83.3%) and 3 in the HK group, which was statistically significant. Nevertheless, there were no clinical signs or symptoms of instability, and thus no patient required further revision in either group. This indicated that soft-tissue healing of the CC space in the CC ligament augmentation patients could be achieved in a non-anatomic position under the permanent stability provided by a non-resorptive suture material such as Mersilene tape.
Regarding acromial osteolysis, the lateral portion of the hook plate could cause subacromial impingement; in other words, the stress on the base of the acromion increases, which could further result in acromion osteolysis, possibly even complicated by fracture. This poor result usually occurs in patients with a hook plate retention of more than 1 year [
24,
38]. This complication could be attributed to an inappropriate size of the implant [
23,
38], or interpreted as a force concentration phenomenon due to morphological mismatch between the acromion and hook plate [
39]. In our series, there were 4 cases of acromion osteolysis in the hook plate fixation group, although removal of the hook implant was carried out between 4 and 6 months after surgery as previously recommended [
23,
24].
Limitations
There were some limitations to this study. First, the number of cases was limited. Second, the assignment of each group was limited in the retrospective nature. In the comparison of two groups, although there was no difference in preoperative classification, the selection bias might be minimal. But the surgical method depended on the surgeon’s preference, which may be a potential confounding factor. Otherwise, long-term complications such as AC joint arthritis or rotator cuff arthropathy should be further monitored. However, we have nevertheless provided prudent and straightforward results after a minimum 5-year follow-up period in this study.
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