Keywords
acromioclavicular joint/injuries - acromioclavicular joint/surgery - joint dislocations
- ligaments, articular
Introduction
The diarthrodial joint between the medial acromial aspect and the side of the clavicle
is called acromioclavicular (AC) joint. Its anteroposterior stability is provided
by the AC ligaments, which consist of thickening portions of the joint capsule, in
which the upper one is the strongest. Superoinferior stability is maintained by the
coracoclavicular (CC), trapezoid and conoid ligaments.[1]
Fukuda et al.,[2] identified that the AC ligaments were the main limiting factors for posterior and
superior translation in minor dislocations. In larger dislocations, the conoid ligament
is the primary limiting factor for upper translation, while the trapezoidal ligament
provides tensile strength to the AC joint.[2]
Injuries to the AC joint typically result from direct trauma to the shoulder caused
by falls and contact sports with the arm in an adducted position. Force deflects the
acromion inferiorly, while the clavicle remains in its anatomical position. This results
in varying degrees of damage to both the AC and CC ligaments.[3]
Williams et al.,[4] based on a study by Tossy et al.,[5] developed a widely-accepted classification system according to anatomical severity,
dividing the injuries into six types. In addition, AC injuries can be divided into
acute (< 3 weeks) and chronic (> 3 weeks) lesions.[6]
[7]
Most authors recommend the non-surgical treatment for type-I and type-II injuries.[1]
[8]
[9] The treatment for type-III lesions is controversial, since several authors have
presented conservatively-treated case series with good to excellent outcomes.[10]
[11] However, other authors have reported cases with pain and other residual symptoms.[12]
[13] In an attempt to maximize the positive outcomes, many authors have advocated the
surgical repair in young, active patients.[14]
[15]
For type-IV, type-V and type-VI lesions, the surgical treatment is established.[1]
[3]
[9]
[14] Multiple techniques for the surgical treatment have been described, but there is
no evidence of the superiority of one when compared to the others. The only consensus
is that, regardless of the approach, five key elements must be reached: anatomical
reduction, CC ligament reconstruction or direct repair, CC ligament protection, deltotrapezoid
fascia repair, and, in chronic lesions, distal resection of the clavicle.[3]
The present study aims to analyze the outcomes of the treatment of acute and chronic
AC dislocations (ACDs) to identify the best time for surgical therapy and to define
a more effective therapeutic plan.
Material and Methods
A retrospective cross-sectional study was conducted with 39 cases of ACD treated surgically
between 2011 and 2018 in 2 private hospitals. Due to the long follow-up and patient
profile, only 30 subjects returned for evaluation. All patients were evaluated radiographically using the anteroposterior (AP) and Zanca
views, including both shoulders, as well as axillary views. Of these patients, 28 were diagnosed at the time of surgery as ACD grade V, while
2 patients were diagnosed as ACD grade III.
Of the 30 patients, 21 had acute injuries (subgroup I) and 9 presented chronic injuries
(subgroup II). The subjects in subgroup I were operated on average 4.5 days after
the trauma, while the patients in subgroup II were operated on average 424 days after
the trauma. Most patients (96.6%) were male. The mean age was 40.7 years in subgroup
I, and 42.1 years in subgroup II. The right side was the most affected, accounting
for 71.4% of the injuries in subgroup I , and for 66.7% of the lesions in subgroup
II ([Table 1]).
Table 1
|
Clinical ariable
|
Acute subgroup (n = 21)
|
Chronic subgroup (n = 9)
|
|
Mean
|
Standard deviation
|
Mean
|
Standard deviation
|
|
Age (years)
|
40.7
|
13.1
|
42.1
|
14.6
|
|
Time until surgery (days)
|
4.5
|
4.0
|
424
|
462
|
|
Time until the return to work (days)[a]
|
73.0
|
49.8
|
78.1
|
49.1
|
|
Time until the return to sports (months)[b]
|
5.3
|
2.8
|
7.50
|
5.01
|
|
Laterality
|
|
|
|
|
|
Right
|
15 (71.4%)
|
6 (66.7%)
|
|
Left
|
6 (28.6%)
|
3 (33.3%)
|
All patients were reevaluated by the same examiner using a postsurgical standardized
protocol consisting of the University of California at Los Angeles (UCLA) Shoulder
Rating score, the Constant-Murley score, the visual analog scale (VAS) score, as well
as of epidemiological data and comparative, contralateral force assessment with a
digital dynamometer. After the evaluation, AP, Zanca and axillary radiographs were performed to determine
the residual displacement of the operated shoulder by comparing its coracoclavicular
distance with the contralateral shoulder.
The experimental design was submitted to and approved by the local ethics committee
under CAAE 95443218.4.0000.0023.
Statistical Methodology
Tables were developed to present the results of the descriptive analysis, with numerical
data expressed as means and standard deviations, and the categorical data expressed
as frequencies and percentages.
In inferential analysis, we compared the subgroups (acute and chronic) using the Mann-Whitney test for the numerical data and the Fisher exact test for the categorical data. Paired data were compared using the Wilcoxon signed-rank test. The Spearman correlation coefficient was used to analyze the association between the numerical variables.
Nonparametric methods were used since the data did not show a normal (Gaussian) distribution,
due to the rejection of the null hypothesis of normality according to the Shapiro-Wilk
test in at least one group and/or time point. Significance was defined at a level
of 5%. The statistical analysis was processed using the SAS System statistical software
(SAS Institute, Inc., Cary, North Carolina, US), version 6.11.
Surgical Technique
The treatment for acute injuries recommended by the authors uses suture anchors and
transarticular fixed Kirschner wires as described by Phemister.[16] The advantages include the small incision and limited dissection above the coracoid
region, with no need for any instrumentation below it, minimizing the risk of neurovascular
injury.
With the patient in the beach chair position, anesthetized with an interscalene block,
the arm and shoulder are prepared. A 5-cm incision is made below the clavicle, at
the level of the coracoid process. The subcutaneous tissue is dissected until the
deltotrapezoid fascia is exposed. A medial to lateral incision is then made following
the curvature of the clavicle until bone exposure.
A blunt dissection is performed until the dorsal base of the coracoid process is exposed.
After satisfactory exposure, two #5 suture anchors are used with two #2 Fiberwire
(Arthrex, Naples, Florida, US) non-absorbable sutures. A 3.2-mm drill is used to make
2 holes in the collarbone, one more posterior, 3.5 cm from the AC joint, and the other
more anterior, 2.5 cm from the AC joint.[17]
[18]
The dislocation is hyper-reduced, and a 2.0-mm Kirschner wire is transfixed by the
AC joint. Its position is confirmed by arthroscopy. After the reduction, each suture
is tied separately. The deltotrapezoid fascia is repaired, and the subcutaneous tissue
and skin are sutured. The Kirschner wires are bent and kept under the skin.
Chronic dislocations are treated using the modified Weaver-Dunn technique. The patient
is positioned and prepared as in the previous procedure. Two suture anchors are placed
at the coracoid process. A medial, 5 cm to 7 cm in length, incision is made at the
AC joint towards the coracoid process. The deltotrapezoid fascia is identified and
incised. The periosteal detachment of the trapezius and deltoid is then performed.
Through blunt dissection, the coracoacromial ligament is identified and detached at
its anteroinferior acromial insertion. The lateral end of the clavicle is excised
about 1.0 cm to 1.5 cm from the lateral edge.
The clavicle is then reduced, and one or two Kirschner wires are passed, transfixing
the AC joint. Two holes are made in the upper cortical layer of the clavicle, and
the end of the coracoacromial ligament is repaired and tied through the clavicular
holes, projecting the ligament into the medullary canal. Suture anchors are tied to
the clavicle, the deltotrapezoid fascia is repaired, and the subcutaneous tissue and
skin are closed. As in acute cases, the Kirschner wires are bent and remain under the skin.
Postoperative Period
In both subgroups, the arm was kept in a three-point American sling for six weeks.
At the end of the sixth week, the Kirschner wire was surgically removed, and mobilization
was allowed. Then, motor physical therapy was started for range of motion and stretching.
Muscle strengthening was allowed after the third postoperative month, and return to
sports was allowed after the fifth month.
Results
Regarding the functional scores, the mean VAS was of 1.10 (standard deviation [SD]:
1.61) in subgroup I, and of 1.11 (SD: 2.09) in subgroup II. The mean Constant-Murley
score was of 92.3 (SD: 7.1) in subgroup I, and of 94.2 (SD: 6.9) in subgroup II. The
mean UCLA score was of 33.5 (SD: 2.2) in subgroup I, and of 32.4 (SD: 4.9) in subgroup
II. There were no significant differences in the functional score at the level of
5% ([Table 2]).
Table 2
|
Variables
|
Acute subgroup (n = 21)
|
Chronic subgroup (n = 9)
|
|
Functional
|
Mean
|
Standard deviation
|
Mean
|
Standard deviation
|
|
VAS score
|
1.10
|
1.61
|
1.11
|
2.09
|
|
Constant-Murley score
|
92.3
|
7.1
|
94.2
|
6.9
|
|
UCLA score
|
33.5
|
2.2
|
32.4
|
4.9
|
|
CC distance (mm)
|
11.0
|
4.0
|
13.8
|
4.1
|
|
Increase in distance (%)
|
8.9
|
14.2
|
22.9
|
24.1
|
|
Force at operated shoulder
|
Mean
|
Standard deviation
|
Mean
|
Standard deviation
|
|
Abduction force (kg)
|
11.1
|
5.4
|
11.5
|
3.4
|
|
Medial rotation force (kg)
|
15.9
|
8.9
|
14.2
|
3.8
|
|
Lateral rotation force (kg)
|
11.2
|
5.1
|
10.5
|
2.9
|
|
Force at the contralateral shoulder
|
Mean
|
Standard deviation
|
Mean
|
Standard deviation
|
|
Abduction force (kg)
|
11.7
|
5.4
|
12.5
|
3.8
|
|
Medial rotation force (kg)
|
15.6
|
9.1
|
14.6
|
4.5
|
|
Lateral rotation force (kg)
|
12.2
|
5.7
|
11.4
|
4.4
|
|
Delta value for force (%)
|
|
|
|
|
|
Delta value for abduction force (%)
|
-2.94
|
-7.54
|
|
Delta value for medial rotation force (%)
|
3.23
|
-1.37
|
|
Delta value for lateral rotation force (%)
|
-7.21
|
-4.68
|
As for force, in subgroup I, the average abduction in the operated arm was of 11.1 kgf
(SD: 5.4), with a delta value for the relative variation comparing the operated and
the contralateral shoulder of -2.94%. In subgroup II, the average abduction in the
operated arm was of 11.5 kgf (SD: 3.4), with a delta value of -7.54%.
In subgroup I, the mean medial rotation force in the operated arm was of 15.9 kgf
(SD: 8.9), with a delta value of -3.23%. In subgroup II, the mean medial rotation
force in the operated arm was of 14.2 kgf (SD: 3.8), with a delta value of -1.37%.
Subgroup I presented an average lateral rotation force of 11.2 kgf (SD: 5.1) in the
operated arm, with a delta value of -7.21%. In subgroup II, the average lateral rotation
force was of 10.5 kgf (SD: 2.9) in the operated arm, with a delta value of -4.68%.
The force-related variables showed no significant difference at the level of 5% ([Table 2]).
The mean CC distance was of 11.0 mm (SD: 4.0) in subgroup I, and of 13.8 mm (SD: 4.1 mm)
in subgroup II. In subgroup I, 38.09% of the patients presented AC-joint subdisclocation,
with an average increase in CC space compared to the contralateral shoulder of 8.9%
(SD: 14.2); in subgroup II, 66.66% of the patients presented said subdislocation,
with an average increase of 22.9% (SD: 24.1). The subjects in subgroup I tended to
present a lower CC distance (p = 0.098) and a lower percentage increase in CC distance (p = 0.095) compared to subgroup II. In addition, there was no significant correlation,
at the level of 5% between the percentage of increased distance with functional and
force parameters, both in the total sample and in subgroups I and II.
The average time until the return to work was of 73 days for subgroup I, and of 78.1
days for subgroup II. The average time until the return to sports was of 5.3 months
(SD: 2.8) in subgroup I, and of 7.5 months (SD: 5.01) in subgroup II.
Functional and force results are shown in [Table 2].
Discussion
There is no consensus in the current literature on which is the best surgical technique
to treat chronic and acute ACDs. Scientific publications have presented outcomes from
several therapeutic modalities for these injuries, but few compare the techniques
used in each of these cases. We evaluated the outcomes of the surgical treatment of
acute and chronic dislocations and compared them.
Both groups were submitted to surgical techniques following the five key elements
of surgery recommended by Li et al.[3]: anatomical reduction, CC ligament reconstruction or direct repair, CC ligament
protection, deltotrapezoid fascia repair, and, in chronic injuries, distal resection
of the clavicle.
Unlike Von Heideken et al.,[19] who found a statistically significant difference in the Constant-Murley score (91
for the acute group versus 85 for the chronic group), and Rolf et al.,[20] who also reported inferior clinical and functional outcomes in the late reconstruction
group (87.17 versus 78.10), in the present study, there were no statistical differences between subgroup
I and subgroup II regarding the Constant-Murley and UCLA scores.
Tauber et al.[21] observed a mean VAS score of 2.3 points, which is similar to that found by Hegazy
et al.[22] in their series (average score: 1); these findings are in line with our VAS assessment,
with an average of 1.10 points in subgroup I, and 1.11 points in subgroup II, with
no statistical significance.
The mean UCLA score was of 33.5 points (SD: 2.2) in subgroup I, with good/excellent
values (> 27 points) in 95.23% of the subjects. In subgroup 2, the mean UCLA score
was pf 32.4 points (SD: 4.9), with good/excellent values in 88.8% of the cases. There
was no statistically significant difference between the groups. These results are
similar to those reported in the Brazilian literature, with 92.8% of good/excellent
cases according to Molin et al.[23] and 95.2% according to Scandiuzzi et al.[24]
Complications were present in 43.3% of our patients, in a rate that is in line with
that of other studies, such as those by Ferreira Neto et al.[25] (40.9%) and Neviaser[26] (39%). Superficial infection occurred in 14.21% of the cases on subgroup I, and
in 11.11% of the subjects in subgroup II. All cases were treated with oral antibiotic
therapy and daily dressings, with no cutaneous suture dehiscence or clinical repercussions.
Another complication observed was the lateral migration of the AC Kirschner wire in
a group-I patient (4.76%), which was treated with the removal of the synthesis material
and no further intercurrence. Residual pain was reported by 14.28% of the subjects
in subgroup I and 11.11% of the patients in subgroup II.
Clavicular prominence was reported by 4.76% of the patients in subgroup I, and by
22.2% of the subjects in subgroup 2. A radiologically-assessed increase in CC space
higher than 12 mm was observed in 8.9% (SD: 14.2) of the subjects in subgroup I, and
in 22.9% (SD: 24.1) of the patients in subgroup II. Although there was no significant
difference at the level of 5%, the subgroup-I patients tended to present lower CC
distance (p = 0.098) and lower percentual increase in CC distance compared to the contralateral
side (p = 0.095) than the subgroup-II patients.
Despite the high incidence of this deviation as a complication, it had no final impact
on level of satisfaction of the patients. In addition, no patient presented scapular
dyskinesia, which corroborates literature reports that anatomical reduction is not
always required to restore adequate shoulder function, and that the loss in reduction
does not seem to significantly influence the outcomes.[12]
[27]
[28]
In total, 28 patients (93.3%) were satisfied with the treatment, with no statistically
significant difference between the subgroups. This is in line with the literature,[13] suggesting that there is no relationship between the clinical and radiographic findings.
The main limitations of the present study are its retrospective nature, the relatively
low number of patients, and the discrepancy between the subgroups.
Conclusion
We conclude that the surgical treatment of ACDs presents satisfactory outcomes both
in acute and chronic cases. However, due to the greater trend for residual dislocation
with the increased CC space in chronic cases, we should seek to treat these injuries
immediately after the trauma.
