Anatomic Coracoclavicular Ligament Reconstruction
for the Treatment of Acute Acromioclavicular Joint
Dislocation
Minimum 10-Year Follow-up
Daisuke Mori, MD, Fumiharu Yamashita, MD, PhD, Kazuha Kizaki, MD, Noboru Funakoshi, MD, Yasuyuki Mizuno, MD, andMasahiko Kobayashi, MD, PhD
Investigation performed at Kyoto Shimogamo Hospital, Kyoto, Japan

Background: The long-term clinical and radiographic outcomes following coracoclavicular (CC) ligament reconstruction
for the operative treatment of acute acromioclavicular (AC) joint dislocation remain uncertain. The purpose of the present
study was to determine the long-term clinical and radiographic outcomes of CC ligament reconstruction and to identify risk
factors for unfavorable outcomes.
Methods: We reviewed 20 cases of AC joint dislocation in 19 patients (18 male and 1 female; mean age, 32.3 years) thatwere treated with single-bundle reconstruction. The mean duration of follow-up was 12.7 years. We measured the CC
vertical distance (CCD) on the anteroposterior view and compared the affected and unaffected sides (CCD ratio). We
divided the patients into those with a CCD ratio of <25% (Group 1) and those with a CCD ratio of ‡25% (Group 2). We
radiographically investigated the clavicular tunnel anteroposterior (CTAP) angle, clavicular tunnel ratio, and coracoid
tunnel orientation on the basis of the entry and exit points at the base of the coracoid. For the coracoid tunnel orientation,
we compared center-center orientation and noncenter-center orientation.
Results: Group 1 comprised 17 cases (85%), and Group 2 comprised 3 cases (15%). At the time of the latest follow-up,
Group 1 had a signiﬁcantly higher mean Constant score than Group 2 (98.2 compared with 90.7; p = 0.038). Of the 3radiographic parameters, only the CTAP angle was signiﬁcantly different between the 2 groups (p < 0.0001). Two (67%) of
the 3 cases in Group 2 were associated with posterior AC joint displacement.
Conclusions: CC ligament reconstruction for the treatment of acute AC joint dislocation resulted in successful long-termclinical and radiographic outcomes. It is important to decrease the CTAP angle and to ensure proper anatomic placementof the clavicular and coracoid tunnels at the time of surgery.
Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

M

any nonanatomic procedures for the operative
treatment of acute acromioclavicular (AC) joint
dislocation have been proposed, including coracoacromial ligament transfer and Bosworth screw or pin ﬁxation1,2.
However, these procedures are performed less frequently thanthey had been in the past because of their high complication
rates1,2. More recently, anatomic coracoclavicular (CC) ligament
reconstruction has become popular in the hope of decreasing
complication rates and improving patient outcomes. Somestudies have demonstrated higher clinical success rates andsuperior biomechanical outcomes when CC ligament reconstruction has been compared with other techniques1-5. However, the detailed operative techniques, complication rates, andfollow-up periods have differed among studies6-13. To ourknowledge, the longest mean duration of follow-up for thisprocedure was 5.2 years, as reported by Struhl and Wolfson6.
The long-term (>10-year) clinical and radiographic outcomesof this procedure remain uncertain6-13.

Disclosure: The authors report no conﬂicts of interest. No outside funding was received for this study. The Disclosure of Potential Conﬂicts of Interest
forms are provided with the online version of the article (http://links.lww.com/JBJSOA/A16).
Copyright  2017 The Authors. Published by The Journal of Bone and Joint Surgery, Incorporated. All rights reserved. This is an open-access article distributed under the terms of
the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited.
The work cannot be changed in any way or used commercially without permission from the journal.

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2ä

TABLE I Demographic Data and Radiographic Variables of the Single-Bundle Group*†

Sex,
Age
(yr)

Interval
BetweenInjury andSurgery (d)

1

M, 21

2

M, 20

3

F, 75

4§

M, 16

5
6§

M, 18
M, 18

7

M, 25

5

R

V

Sport

129

100

100

8

M, 20

4

L

V

Sport

125

100

100

9

M, 17

3

L

V

Sport

156

100

100

10

M, 19

6

L

III

Sport

124

98

96.7

11

M, 22

12

L

V

Sport

165

100

100

12
13

M, 43
M, 36

12
19

L
R

V
V

Sport
Motor-vehicle accident

203
186

98
98

100
100

14

M, 44

5

L

IV

Sport

174

96

100

15

M, 31

11

R

III

Sport

151

100

100

16

M, 38

17

R

IV

Sport

140

95

95

17

M, 55

11

R

V

Motor-vehicle accident

130

100

100

18

M, 48

6

R

V

Motor-vehicle accident

126

84

90

19

M, 53

8

R

V

Fall from height

149

100

100

20

M, 26

34

L

V

Sport

145

88

95

Case

InjuryMechanism

Duration of
Follow-up(mo)Constant
Score(points)

ASES
Score
(points)

100

Side

Rockwood
Type

5

L

V

Sport

186

100

4

R

V

Sport

160

98

100

5

R

V

Motor-vehicle accident

153

87

100

2

L

V

Sport

154

100

100

10
12

R
R

V
V

Sport
Sport

145
135

100
100

100
100

Group 1
Group 1A

Group 1B

Group 2

*ASES = American Shoulder and Elbow Surgeons, CCD = coracoclavicular distance, CTR = clavicular tunnel ratio, CTAP = clavicular tunnel
anteroposterior, and CCL = coracoclavicular ligaments. †Postoperatively, patients were only allowed to perform passive range-of-motion exercises
up to a ﬂexion and abduction of 90 in the ﬁrst 4 weeks postoperatively. Free passive range of motion was allowed from postoperative Week 5, andstrengthening exercises were started at postoperative Week 6. After 6 weeks, no further restrictions were applied to the range of motion andstrengthening exercises. ‡Ossiﬁcation radiographically visible in coracoclavicular interspace. §The same patient underwent index surgery on theleft side at 16 years of age, and on the right side at 18 years of age. #CCD value in millimeters.

We developed an anatomic CC ligament reconstruction
technique involving the use of artiﬁcial ligaments for the treatment of acute high-grade AC joint dislocation and unstabledistal clavicular fractures, applying the principles of anterior
cruciate ligament reconstruction described in 199814,15. The
purposes of the present study were to determine the long-termclinical and radiographic outcomes of CC ligament reconstruction and to identify risk factors for unfavorable outcomes.
Materials and Methods
he local institutional review board approved the study
protocol. All patients provided informed consent before
inclusion in the study.

T

Patients
Twenty-four patients with acute AC joint dislocation were managed with anatomic CC ligament reconstruction with use of therectangular ENDOBUTTON device (12 · 4 mm) (Smith andNephew) and a Trevira-hochfest artiﬁcial ligament (2.5 · 1 · 250mm) (Telos, SARL) by 1 senior surgeon (F.Y.) at our institution
from September 1998 to December 200414. We contacted all 24
patients by telephone to request their inclusion in the present
study. One patient had moved to another country, and another
patient declined inclusion because of the absence of shoulder
symptoms. We followed the remaining 22 patients, 1 of whom wasmanaged with the single-bundle technique but declined radiographic reassessment and 2 of whom were managed with the
double-bundle technique (see Appendix). One patient was managed with the single-bundle technique bilaterally. Consequently,
the cohort comprised 20 shoulders in 19 patients who weremanaged with the single-bundle technique and were available forclinical and radiographic assessments at the time of the latest
follow-up (Table I). The indication for surgery was acuteAnatomic Coracoclavicular Ligament Reconstruction for Acute Acromioclavicular Joint DislocationJBJS Open Access d 2017:e0007.

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3

TABLE I (continued)

CCD
Ratio
(%)

22.1
23.2

CTR

Coracoid
TunnelOrientation(Entry-Exit)

CTAP
Angle
(deg)

Posterior
Displacement

Implant
Pullout

Ossiﬁcation‡

Osteoarthritis

Suture
of
Torn
CCL

0.17
0.17

Lateral-lateral
Center-center

4.0
3.0

2
–

–
–

–
–

1
1

–
–

252.1

0.14

Center-center

1.5

–

–

1

1

–

8.1#

0.19

Center-center

3.2

–

1

–

1

–
1

213.7

0.17

Center-lateral

2.5

–

–

–

1

10.1#

0.12

Lateral-lateral

1.3

–

–

1

1

–

4.5

0.15

Lateral-lateral

0.8

–

–

–

1

1

9.4

0.17

Center-center

1.0

–

–

1

1

–

221.7
2.4

0.14
0.16

Lateral-lateral
Center-lateral

0.5
2.7

–
–

–
–

–
–

1
1

–
1

22.0

0.22

Center-center

2.2

–

–

–

1

–

24.3

0.16

Lateral-lateral

2.2

–

–

–

1

–

22.8

0.17

Center-center

1.0

–

–

–

1

–

11.9

0.25

Center-center

2.0

–

–

–

–

–

13.4

0.17

Center-center

0.8

–

–

–

–

–

18.1
11.7

0.17
0.15

Lateral-lateral
Center-center

1.5
1.8

–
–

–
1

–
–

1
1

–
1

–
1

1
1

–
–

–

1

–

56.9

0.16

Center-lateral

11.2

1

–

55.4
87.2

0.15
0.17

Center-center
Center-center

21.2
4.0

1
–

–
–

Rockwood type-IVor VAC joint dislocation or Rockwood type-III
dislocation among athletes and high-demand manual laborers1,2,16.
The preoperative clinical scores could not be determined because
the patients had post-injury pain and discomfort12.
Single-Bundle TechniqueHighlights of the operative techniques are shown in Figs. 1-A
through 1-H. The goals of the procedure were to heal the freshly
ruptured soft tissue and to reduce complications such as recurrent
AC instability and postoperative fracture of the coracoid and/or
clavicle1,2,17,18. The patient was placed in the beach-chair position. A
vertical skin incision was made from approximately 3 cm medial
to the AC joint line toward the coracoid process. The deltotrapezial fascia was split in the coronal plane, and the deltoid
muscle was released from the anterior edge of the distal aspect of
the clavicle. The surgeon identiﬁed the coracoid process and theruptured CC ligaments before drilling from superior to inferior
through both cortices of the central portion of the coracoid basewith a 3.5-mm drill-bit. The surgeon then drilled the same coracoid tunnel with a 4.5-mm drill-bit in the same direction to avoid
blowout of the coracoid process (Fig. 1-E). The artiﬁcial ligament
was passed through the medial 2 holes of the ENDOBUTTON(Fig. 1-H) and was attached with a polydioxanone traction suture
through a lateral hole of the button. The traction suture wasintroduced through the coracoid tunnel. The surgeon pulled thetraction suture to introduce the distal button through the coracoid
hole, and then the button was ﬂipped into the horizontal position(Fig. 1-B). While maintaining anatomic reduction of the AC joint,
the surgeon pulled the 2 ends of the ligament vertically to determine the optimal position of the clavicular tunnel approximately
25 mm medial to the lateral end of the clavicle (Fig. 1-F)19. The
surgeon drilled the identiﬁed point with a 3.5-mm drill-bit,
aiming for the coracoid tunnel (Fig. 1-G). With use of a wire loop,
the free ends of the ligament were then shuttled through the
3.5-mm clavicular tunnel. The 2 ends of the ligament were consecutively passed through the button holes (Fig. 1-C). Before reduction, the prevalently ruptured AC joint disc was resected or
sutured. While reduction of the AC joint was maintained, the 2ends were tied via a surgeon’s knot and 3 square knots (Fig. 1-D).
The surgeon then checked the AC stabilization by testing passive
shoulder motion; no shoulder required additional Kirschner wiretransﬁxation in the AC joint. When possible (4 shoulders), thestumps of the torn CC ligaments were sutured with 2-0 Prolene(Ethicon) (Fig. 1-D). The deltotrapezial fascia and the superior

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4Fig. 1

Figs. 1-A through 1-H Illustrations and photographs showing the anatomic coracoclavicular ligament reconstruction technique. Fig. 1-A Dislocated AC joint.
Fig. 1-B The ENDOBUTTON is placed centrally under the coracoid base. Figs. 1-C and 1-D The free ends of the ligament are introduced through the claviculartunnel and are secured by means of a surgeon’s knot. Fig. 1-E The 3.5-mm coracoid tunnel is drilled with a 4.5-mm drill-bit in the same direction. * = coracoid
process. Fig. 1-F The surgeon determines the optimal portion of the clavicular tunnel at approximately 25 mm medial to the lateral end of the clavicle bypulling the artiﬁcial ligament vertically. * = distal end of the clavicle. Fig. 1-G The optimal portion is drilled with a 3.5-mm drill-bit, aiming for the coracoid
tunnel. * = distal end of the clavicle. Fig. 1-H Telos artiﬁcial ligament and 2 ENDOBUTTONs.

capsule were imbricated, skin closure was performed, and the arm
was placed in a sling for 3 weeks. Active range of motion could bestarted at 6 weeks postoperatively. Return to full activity was allowed 4 months postoperatively (Table I).
Functional Outcome Measures at Latest Follow-up
Shoulder function was assessed with use of the Constant score andthe American Shoulder and Elbow Surgeons (ASES) score. One
author (not a member of the surgical team) measured the range of
motion in all shoulders with use of a hand-held goniometer.
Radiographic Assessment at Latest Follow-up
The shoulders were evaluated with radiographs and computed tomography (CT), including 3-dimensional (3D) re-constructed CT scanning with an Activion 16 scanner(Toshiba) (spiral scan, 0.5-mm slice thickness, 1.0 pitch,
0.4-mm reconstruction, 3-dimensional [3D] edit mode). We
also assessed the radiographic parameters reported in previous studies1,12,19-26.
Displacement of AC Joint
We measured the CC vertical distance (CCD) between the uppermost border of the coracoid process and the opposing clavicular surface on the anteroposterior radiograph and thencompared the lengths of the affected and unaffected sides (CCD
ratio) (Fig. 2)1,12,21-23. In patients who had undergone bilateralshoulder surgery, we deﬁned a normal CCD as 10 to 13 mm1,20.

Fig. 2The coracoclavicular (CC) distance is measured between the uppermost border of the coracoid process and the opposing clavicular surface. A yellow dashedline is drawn from the medial border of the clavicle to the lateral border. A red solid line is drawn from the lateral border to the center of the bone tunnel. The
clavicular tunnel distance is divided by the clavicular length to obtain the clavicular tunnel ratio.

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5Fig. 3

Figs. 3-A and 3-B 3D reconstructed CT images of the AC joint. Fig. 3-A The clavicle is in line with the acromion (red line), indicating a horizontally stable AC
joint. Fig. 3-B The clavicle is posteriorly displaced (red arrow), indicating a horizontally unstable AC joint.

Clavicular Length
We measured the clavicular length from the midpoint of thesternal border to the midpoint of the lateral margin of the clavicle. From the end point used on the lateral aspect of the clavicle,
distances were measured to the midpoint of the bone tunnel (Fig.
2)23. The distance from the lateral border of the clavicle to thecenter of each bone tunnel (DCTP) was divided by the total
clavicular length to obtain the clavicular tunnel ratio (CTR)23.
Posterior Displacement
We evaluated posterior displacement on radiographs and 3D
CT images (Figs. 3-A and 3-B). Reduction was deﬁned as aclavicle that was in line with the acromion (Fig. 3-A)24, anddisplacement was deﬁned as a clavicle that was not in line withthe acromion (Fig. 3-B)24.
Coracoid Tunnel
We assessed the entry and exit points of the coracoid tunnel atthe base of the coracoid on 3D and axial CT images25. We
divided the coracoid base into 3 regions (medial, center, andlateral) for the tunnel placement (Figs. 4-A and 4-B). Centercenter orientation was taken to represent perfect coracoid
tunnel orientation; we compared center-center orientation andnoncenter-center orientation25.

Fig. 4

Figs. 4-A through 4-E Illustrations and 3D reconstructed CT images showing the divided markings for the entry and exit points of the coracoid
tunnel on the coracoid base. C = center, L = lateral, M = medial. Fig. 4-A The superior aspect of the coracoid base. Fig. 4-B The undersurfaceof the coracoid base. Fig. 4-C Left shoulder. The entry point of the coracoid tunnel (red arrow) is located in the center portion. Fig. 4-D Rightshoulder. The entry point (red arrow) is located in the lateral portion. Fig. 4-E Right shoulder. The button (exit point, red arrow) is located in thecenter portion.

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6Fig. 5

Figs. 5-A and 5-B Illustration and radiograph showing the clavicular tunnel anteroposterior (CTAP) angle, which is the acute angle between the radiographic
midline (red and yellow solid lines) of the clavicular and coracoid tunnels (cylinders in Fig. 5-A and blue dotted lines in Fig. 5-B).

Clavicular Tunnel Anteroposterior Angle
We assessed the clavicular tunnel anteroposterior (CTAP) angle(the angle between the radiographic midline of the bone tunnel
formed in the clavicle and the coracoid process) on anteroposterior radiographs that were made immediately postoperatively (Figs. 5-A and 5-B)26.

Statistical Analysis
We used the unpaired t test with Bonferroni correction to
independently compare postoperative clinical scores, theinterval from injury to surgery, age, and radiographic parameters such as the CTR and the CTAP angle. The Fisher

ENDOBUTTON Pullout
We investigated pullout of the ENDOBUTTONs at the attachment sites8,9,12. Three orthopaedic surgeons (D.M., K.K.,
N.F.) who had not been involved in the earlier treatments
measured the mean CCD, DCTP, and clavicular length inmillimeters and the mean CTAP angle in degrees with use ofdigital calipers in the Picture Archiving and Communication System (PACS), resulting in satisfactory intraclasscorrelation reliability test results (Table II)27. The diagnosisof radiographic appearance in terms of coracoid tunnel
orientation, posterior displacement of the clavicle, ENDOBUTTON pullout, ossiﬁcation in the CC interspace, andosteoarthritis of AC joint was determined by consensus
among the 3 surgeons.

TABLE II Intraobserver and Interobserver Reliability of Radiographic Parameters*
Reliability (95% Conﬁdence Interval)
Parameter

IntraobserverInterobserver

CCD ratio

0.992 (0.980 to 0.997)

0.931 (0.839 to 0.972)

CTR

0.985 (0.962 to 0.994)

0.909 (0.820 to 0.959)

CTAP angle

0.993 (0.982 to 0.997)

0.980 (0.959 to 0.991)*CCD = coracoclavicular distance, CTR = clavicular tunnel ratio,
and CTAP = clavicular tunnel anteroposterior.

TABLE III Variables and Clinical Scores in the Study Cohort

Classification of Patients According to CCD Ratio
Considering the inconsistency of successful clinical and radiographic outcomes in previous studies1,2,20-22,24,26 and our operative purpose of narrowing the CC interspace, we established
an approach based on the operative indication (Rockwood
type-III to V dislocation) to investigate the relationship between clinical and radiographic outcomes. We divided thepatients into 2 groups on the basis of the CCD ratio: Group
1 (CCD ratio of <25%, resembling Rockwood type-I or II
partial dislocation) and Group 2 (CCD ratio of ‡25%, resembling Rockwood type-III, IV, or V dislocation)1. We thenfurther divided Group 1 into two subgroups: Group 1A (CCD
ratio of <10%, resembling Rockwood type I) and Group 1B(CCD ratio of 10% to 25%, resembling Rockwood type II)
because our ultimate operative purpose was to maintain the AC
joint as it was in Group 1A.

Variable

Total Cohort (N = 20)

Constant score* (points)

97.1 ± 4.9

ASES score*† (points)

98.8 ± 2.7

Male:female ratio‡ (no. of patients)

18:1

Age* (yr)32.3 ± 16.3

Dominant-side surgery (no. of shoulders)

11 (55.0%)

Interval between injury and surgery* (d)9.6 ± 7.4 (2 to 34)

Duration of follow-up* (mo)151.8 ± 22.2

Sports injury (no. of shoulders)

15 (75.0%)*The values are given as the mean and the standard deviation,with or without the range in parentheses. †ASES = American
Shoulder and Elbow Surgeons. ‡One male patient underwent theindex surgery bilaterally.

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7

Fig. 6

Figs. 6-A through 6-D Radiographs and 3D reconstructed CT image for the 1 patient who underwent single-bundle coracoclavicular ligament reconstructionof both shoulders (Cases 4 and 6). Fig. 6-A Anteroposterior radiograph made at the time of the latest follow-up. The red circle shows ossiﬁcation in thecoracoclavicular interspace, and the yellow circle shows pullout of the distal ENDOBUTTON. Fig. 6-B 3D reconstructed CT image made at the time of thelatest follow-up. The yellow circle shows pullout of the distal ENDOBUTTON. Fig. 6-C Anteroposterior radiograph made 12 months postoperatively. The yellow
circle shows the distal ENDOBUTTON seated on the undersurface of the coracoid. Fig. 6-D Anteroposterior radiograph made 132 months postoperatively. The
yellow circle shows pullout of the distal ENDOBUTTON.

exact test with Bonferroni correction was used to independently compare posterior displacement, coracoid tunnel orientation (center versus noncenter), and Rockwoodclassiﬁcation (type III versus type IV or V). We used 1-way
analysis of variance to calculate intraobserver and interobserver reliability correlations of repeated interval scale mea-sures. The level of signiﬁcance was set at p < 0.05. Statisticalanalyses were performed with SAS software (version 9.13).
Results
he cohort consisted of 20 shoulders in 19 patients (18 maleand 1 female) with a mean age of 32.3 years at the time ofT

TABLE IV Comparison of Multiple Variables Between Groups*

Variable

CCD Ratio <25%

CCD Ratio ‡25%

P ValueGroup 1
Group 1A
Group 1B
(CCD Ratio <25%) (CCD Ratio <10%) (10% £ CCD Ratio(N = 17)(N = 10)<25%) (N = 7)Group 2
(N = 3)

Group 1 vs. Group 1A vs. Group 1A vs. Group 1B vs.
Group 2
Group 1B
Group 2
Group 2

Constant score† (points)

98.2 ± 3.3

98.3 ± 4.1

98.1 ± 2.0

90.7 ± 8.3

0.038‡>0.9990.177

0.174§

ASES score† (points)

99.5 ± 1.4

99.7 ± 1.0

99.3 ± 1.9

95.0 ± 5.0

0.013‡>0.9990.045‡

0.285§>0.999§CTR†

0.17 ± 0.03

0.16 ± 0.02

0.18 ± 0.04

0.16 ± 0.01

>0.9990.356>0.999

CTAP angle† ()1.9 ± 1.0

2.1 ± 1.2

1.6 ± 0.5

12.1 ± 8.6<0.001‡>0.9990.008‡

0.032‡§

Coracoid tunnel orientation(center vs.
noncenter)# (no. ofshoulders)

9 vs. 8

4 vs. 6

5 vs. 2

2 vs. 1>0.999>0.999>0.999>0.999**Posterior displacement (no.
of shoulders)

0

0

0

2

0.063

—

0.154

0.267**

Rockwood type III vs. IV or V
(no. of shoulders)

2 vs. 15

1 vs. 9

1 vs. 6

0 vs. 3>0.999>0.999>0.999>0.999**Interval between trauma andsurgery† (d)8.4 ± 5.0

5.6 ± 3.1

12.4 ± 4.5

16.0 ± 15.6

0.408

0.009‡

0.205>0.999§Age† (yr)30.5 ± 16.3

24.9 ± 17.8

38.4 ± 10.5

42.3 ± 14.4

>0.999

0.370

0.608

>0.999§*CCD = coracoclavicular distance, ASES = American Shoulder and Elbow Surgeons, CTR = clavicular tunnel ratio, and CTAP = clavicular tunnel anterior posterior. †The
values are given as the mean and the standard deviation. ‡Signiﬁcant. §Unpaired t test with Bonferroni correction. #“Center” indicates that both the entry and the exit
point of the coracoid tunnel were located in the center portion of the coracoid base. **Fisher exact test with Bonferroni correction.

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8Fig. 7

Figs. 7-A through 7-F Preoperative (Figs. 7-A, 7-C, and 7-E) and postoperative (Figs. 7-B, 7-D, and 7-F) anteroposterior radiographs. Figs. 7-A and 7-B Case
15 (Rockwood type III; CCD ratio, 13.4%). Figs. 7-C and 7-D Case 14 (Rockwood type IV; CCD ratio, 11.9%). Figs. 7-E and 7-F Case 18 (Rockwood type V;
CCD ratio, 56.9%).

Fig. 8

Figs. 8-A through 8-E Case 5. Follow-up photographs and radiographs. Fig. 8-A Postoperative photograph of both shoulders. Fig. 8-B Postoperative
photograph of the right shoulder, showing a slight protrusion around the AC joint. Fig. 8-C Postoperative anteroposterior radiograph of the rightshoulder, showing osteoarthritic changes of the AC joint. Fig. 8-D Postoperative anteroposterior radiograph of the left shoulder. Fig. 8-E Postoperative
photograph of the left shoulder.

Anatomic Coracoclavicular Ligament Reconstruction for Acute Acromioclavicular Joint DislocationJBJS Open Access d 2017:e0007.

surgery. The dominant shoulder was involved in 11 cases. The
mean interval between the injury and surgery was 9.6 days. The
mean duration of postoperative follow-up was 12.7 years(151.8 months; range, 124 to 203 months). The mechanism of
injury was sports-related for 14 patients, a fall from a height for
1 patient, and a motor-vehicle accident for 4 patients. According to the Rockwood classiﬁcation, there were 2 type-III, 2
type-IV, and 16 type-V dislocations. The mean Constant and
ASES scores were 97.1 and 98.8, respectively (Tables I and III).
Radiographic and Clinical Outcomes and Complications in
Multiple Groups
In the 1 patient who underwent the procedure bilaterally, theCCD and CTR were 10.1 mm and 0.12, respectively, on theright side and 8.1 mm and 0.19, respectively, on the left side at
the time of the latest follow-up (Fig. 6); hence, both shoulders
in this patient were included in Group 1. There were 10
shoulders in Group 1A, 7 in Group 1B, and 3 in Group 2 (Table
IV). The mean CTR ranged from 0.16 to 0.18 in all groups. The
mean Constant and ASES scores and CTAP angles were signiﬁcantly different between Groups 1 and 2 (98.2 comparedwith 90.7 [p = 0.038], 99.5 compared with 95.0 [p = 0.013], and1.9 compared with 12.1 [p < 0.001], respectively) (Table IV
and Fig. 7). Of the radiographic variables that were related tothe operative technique (CTR, CTAP angle, and coracoid
tunnel orientation), only the CTAP angle signiﬁcantly differed
between Groups 1 and 2. There were no signiﬁcant differencesin clinical scores or the 3 radiographic variables between
Groups 1A and 1B. There were 11 cases of center-center coracoid tunnel placement, 6 of lateral-lateral tunnel placement,
and 3 of center-lateral tunnel placement. Two of the 3 shoulders in Group 2 had posterior displacement of the AC joint(Table I). Only 2 shoulders (Cases 4 and 17) had pullout of thecoracoid button with reduction of the AC joint (Fig. 6). Fourshoulders showed postoperative ossiﬁcation in the CC interspace (Fig. 6-A). Eighteen shoulders showed radiographic signsof AC joint osteoarthritis (Fig. 8). No patient had intraoperative or postoperative clavicular or coracoid fracture, infection, or any form of osteolysis around the ENDOBUTTONs.
Discussiono our knowledge, the mean duration of follow-up in thepresent study (12.7 years) is the longest reported follow-up
for anatomic CC ligament reconstruction. The overall results ofthis CC ligament reconstruction technique were very successful, with high mean Constant and ASES scores (97.1 and 98.8,
respectively) that were comparable with those in previous
studies: the mean Constant and ASES scores were both 98.0 at amean of 5.2 years as reported by Struhl and Wolfson6, and themean Constant score was 96.6 at a mean of 17 months asreported by Yoo et al.28. Furthermore, there were no complications such as coracoid and/or clavicular fractures related tothe index procedures, and no revision procedures had been
performed after a minimum duration of follow-up of 10 years.
Interestingly, 2 shoulders (Cases 4 and 17) had pullout of thecoracoid button with maintenance of AC joint reduction. ThisT

openaccess.jbjs.org

9ﬁnding suggests that this technique potentially can result in AC
stabilization with complete soft-tissue healing even if the artiﬁcial ligament is disrupted. Seventeen shoulders (85%) had a
CCD ratio of <25% and no posterior AC displacement inconjunction with signiﬁcantly higher clinical scores comparedwith those for the shoulders with a CCD ratio of ‡25%;
however, degenerative changes still developed in the AC joint.
The satisfactory radiographic results may have beenachieved for the following reasons. First, our choice of operative drill diameter (3.5 mm for the clavicular tunnel, 4.5 mm
for the coracoid tunnel) and ENDOBUTTON size (4 · 12 mm)
were supported by previous studies. A 4.5-mm coracoid tunnel
is reportedly superior to a 6-mm coracoid tunnel for biomechanically rigid ﬁxation after CC ligament reconstruction29, theTelos ligament has good mechanical properties (ultimate tensile strength, 1,866 N; stiffness, 68.3 N/mm) compared withnatural ligament30 (ultimate tensile strength, 1,730 N; stiffness,
182 N/mm), and the pullout strength of a metallic button is>1,150 N31,32. Hence, our choices of implant and ligament
were appropriate for rigid intraoperative ﬁxation of the CC
interspace and avoidance of implant migration into the clavicular and/or coracoid tunnel.
Second, the clavicular tunnel could have been locatedinside the anatomic insertion of the CC ligaments in the present study, considering that the mean CTR ranged from 0.16 to
0.18 in all groups (Table IV). In 1 anatomic study, the ratio ofthe distance from the lateral clavicular edge to the conoid
center to clavicular length was 23.8% and the ratio of the distance from the lateral clavicular edge to the trapezoid center toclavicular length was 17.6%33; in another study, these ratios
were 25.5% and 15.6%, respectively34. Those reports support
the location of our clavicular tunnel placement inside the attachment of the CC ligaments as an anatomically proper position33,34, even allowing for anatomic variance of the CC
ligaments35.
Third, the placement of the coracoid tunnel was locatedat the base of the coracoid in all shoulders, although not all
shoulders had center-center coracoid tunnel orientation. The
coracoid tunnel orientation did not signiﬁcantly inﬂuence radiographic outcomes among the groups (Table IV). The entry
point of the coracoid tunnel was located at the base of thecoracoid in all shoulders, although only 11 shoulders (55%)
had center-canter coracoid tunnel orientation. A previous cadaveric study demonstrated no signiﬁcant difference between abase-centered and distal-centered 4.5-mm tunnel at the base of
the coracoid with respect to the mean ultimate load and energy
at ultimate load29. Additionally, Yi and Kim26 investigated theinﬂuence of speciﬁc radiographic parameters on radiographic
results following the use of the single TightRope (Arthrex)
technique and found no signiﬁcant difference in the tunnel-tomedial coracoid ratio between dissociated and nondissociatedgroups. Our results are consistent with the results of those 2
studies26,29 because the location of the coracoid tunnel did not
signiﬁcantly differ between the 2 groups.
Fourth, the mean CTAP angle in Group 1 (1.9) had amore perpendicular placement compared with that in Group 2Anatomic Coracoclavicular Ligament Reconstruction for Acute Acromioclavicular Joint DislocationJBJS Open Access d 2017:e0007.

openaccess.jbjs.org(12.1). The CTAP angle in patients with dissociation is reportedly more acute than the angle in patients with nondissociation, indicating better clinical outcomes in the latterpatients26. In the present study, only the CTAP angle signiﬁcantly differed between Groups 1 and 2. The clinical results inGroup 2 were signiﬁcantly inferior to those in Group 1. Given
these clinical and radiographic results, a lower CTAP angle
seems to be desirable for a good outcome. Surgeons should
intraoperatively monitor the direction of the coracoid andclavicular tunnels to produce a lower CTAP angle10,26. This
monitoring is reportedly facilitated during arthroscopicallyassisted surgery with use of a transclavicular-transcoracoid
drilling guide and ﬂuoroscopy despite longer operation times
and the risk of coracoid fracture36.
The present study had several limitations. First, it had asmall sample size, especially in Group 2. The limited statisticalpower meant that the CTAP angle was not conclusively determined to be a signiﬁcant predictive factor of an unfavorable
outcome, despite the fact that the CTAP angle signiﬁcantly
differed between Groups 1 and 226. Nevertheless, we believethat the CTAP angle is an important operative factor affecting
outcome. Previous studies have indicated that the interval between trauma and surgery and the age at the time of trauma
signiﬁcantly inﬂuence clinical and radiographic outcomes2,10;
however, in the present study, these 2 factors did not signiﬁcantly inﬂuence the outcomes in either group, possibly becauseof the small sample size. Second, the present study was retrospective and had no control group. Third, using clinical scoresand classifying patients on the basis of the CCD ratio have notyet been validated for the assessment of AC joint dislocations.
Indeed, considering the small sample sizes in the groups, thestatistical results could not demonstrate the superiority ofGroup 1A over 1B. However, we consider that reduction of the
AC joint by <25% of the CCD ratio is desirable for better longterm outcomes on the basis of the comparative results between
Groups 1A and 1B and between Groups 1 and 2. Fourth, 2 ofthe 3 patients in Group 2 (Cases 18 and 20) had lower clinical10

scores because of pain than did the patients in Group 1,
whereas 1 patient (Case 19) had maximum clinical scores. One
possible explanation is that the latter patient (Case 19) achieved
full range of motion and strength without pain because ofcomprehensive scapulothoracic functionality2,6,37.
In conclusion, the present study showed successful clinicaland radiographic outcomes at a minimum of 10 years after
anatomic CC ligament reconstruction for the treatment of acute
AC joint dislocation. Longer-term successful outcomes may
be achieved by ensuring the proper direction of drill-holes tocreate a lower CTAP angle and anatomically proper placement of
the clavicular and coracoid tunnels intraoperatively.
Appendix
A table showing baseline variables and clinical scoresfor 1 patient who declined radiographic examinations
and 2 patients who were managed with the double-bundle
technique as well as radiographs of Case 2 are available
with the online version of this article as a data supplement at
jbjs.org (http://links.lww.com/JBJSOA/A17). n
NOTE: The authors are grateful to Yoshihiko Tsuda (medical illustrator, Davinci Medical Illustration
Ofﬁce), to Hajime Yamakage, MD, for the statistical analyses, and to Mutsumi Nishida, PhD,
Naoki Umatani, MD, Hideo Ito, MD, and Hiroshi Funakoshi, MD, for valuable discussion.

Daisuke Mori, MD1
Fumiharu Yamashita, MD, PhD1
Kazuha Kizaki, MD1
Noboru Funakoshi, MD1
Yasuyuki Mizuno, MD1
Masahiko Kobayashi, MD, PhD1
1Kyoto Shimogamo Hospital, Kyoto, Japan

E-mail address for D. Mori: altair.0421@gmail.com
ORCID iD for D. Mori: 0000-0002-4287-2654

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