Stabilisation for the Disrupted Acromioclavicular Joint Using a Braided Polyester Prosthetic Ligament

Abstract

To report outcomes of 21 men who underwent stabilisation for the disrupted acromioclavicular joint (ACJ) using a braided polyester prosthetic ligament.
21 men aged 23 to 76 (mean, 43) years underwent stabilisation for the disrupted ACJ of Rockwood type 3 (n=12), type 4 (n=1), and type 5 (n=8) using a braided polyester prosthetic ligament.
The mean time from injury to surgery was 6.8 (range, 0-19) months. The mean follow-up duration was 30 (range, 7-67) months. The mean Constant Score was 86.8 (range, 62-100), and the mean individualised Constant Score was 88.5 (range, 68-100). The mean Oxford Shoulder Score was 43.1 (range, 28-48). The mean abduction power of the operated side was 82% (range, 31%-97%) that of the normal side. 20 patients were satisfied with the procedure. One patient was dissatisfied who developed scapulothoracic bursitis. One patient required arthroscopic subacromial decompression for impingement. One patient sustained a redislocation following a fall at 6 weeks and declined further surgery.
The braided polyester prosthetic ligament achieved good outcome for patients undergoing stabilisation for the disrupted ACJ.

Full text

ABSTRACT
Purpose. To report outcomes of 21 men who
underwent stabilisation for the disrupted
acromioclavicular joint (ACJ) using a braided
polyester prosthetic ligament.
Methods. 21 men aged 23 to 76 (mean, 43) years
underwent stabilisation for the disrupted ACJ of
Rockwood type 3 (n=12), type 4 (n=1), and type 5
(n=8) using a braided polyester prosthetic ligament.
Results. The mean time from injury to surgery was 6.8
(range, 0–19) months. The mean follow-up duration
was 30 (range, 7–67) months. The mean Constant Score
was 86.8 (range, 62–100), and the mean individualised
Constant Score was 88.5 (range, 68–100). The mean
Oxford Shoulder Score was 43.1 (range, 28–48). The
mean abduction power of the operated side was 82%
(range, 31%–97%) that of the normal side. 20 patients
were satised with the procedure. One patient was
dissatised who developed scapulothoracic bursitis.
One patient required arthroscopic subacromial
decompression for impingement. One patient
Stabilisation for the disrupted
acromioclavicular joint using a braided
polyester prosthetic ligament
Jonathan Wright, Donald Osarumwense, Fikry Ismail, Yvonne Umebuani, Samuel Orakwe
Queen Elizabeth Hospital, Woolwich, London, United Kingdom
Address correspondence and reprint requests to: Jonathan Wright, Queen Elizabeth Hospital, Woolwich, London, SE18 4QH,
United Kingdom. Email: jwrightortho@gmail.com
Journal of Orthopaedic Surgery 2015;23(2):223-8
sustained a redislocation following a fall at 6 weeks
and declined further surgery.
Conclusion. The braided polyester prosthetic
ligament achieved good outcome for patients
undergoing stabilisation for the disrupted ACJ.
Key words: acromioclavicular joint; shoulder dislocation
introduction
Acromioclavicular joint (ACJ) injuries occur more
frequently in men aged <35 years and account for
12% of shoulder girdle injuries.1,2 The mechanism of
injury involves a direct blow to the shoulder tip in the
adducted arm (particularly during contact sports such
as rugby, wrestling, and hockey).3 Forces applied to
the lateral aspect of the shoulder lead to inferior and
medial displacement of the scapula and clavicle. As
the clavicle and the distance of inferior displacement
are limited by the rst rib, the force is redirected to
the acromioclavicular (AC) and coracoclavicular
(CC) ligaments. Greater forces can lead to complete
disruption of the AC ligament and then the CC

224 J Wright et al. Journal of Orthopaedic Surgery
ligament, and even the muscular attachments of
the deltoid and trapezius. This can lead to inferior
subluxation of the acromion to the distal clavicle, as
the supporting structures are disrupted.
According to the Rockwood classication,4,5 there
are 6 types of ACJ injury. Type 1 is a simple sprain.
Type 2 involves a disrupted AC ligament but an intact
CC ligament. Type 3 involves disruption of both AC
and CC ligaments. Type 4 involves disruption of both
ligamentous complexes, with posterior displacement
of the clavicle through the trapezius fascia. Type 5
involves a greater level of disruption of both AC
and CC ligaments; the deltotrapezial fascia is torn
from the lateral attachments to the clavicle. Type 6
is caused by extreme hyperabduction, in which the
clavicle is inferiorly displaced to a subcoracoid or
subacromial position, with high risk of neurovascular
compromise.
In terms of radiographic appearance, type 1
shows normal appearance; type 2 shows some
widening of the ACJ but with a normal CC distance;
type 3 shows further disruption of the ACJ with 20%
to 100% increase in the CC distance; type 4 can be
missed on anteroposterior view but can be seen on
axillary view; and type 5 shows >100% increase in
the CC distance (Fig. 1).5,6 Weightbearing views (5 kg
weight applied to both normal and injured sides) can
maximise displacement to differentiate types.
In terms of treatment, types 1 and 2 can be
treated conservatively with immobilisation in a
broad arm sling until symptoms subside.5 Type 3
can be treated conservatively or operatively; both
achieve similar patient satisfaction.7 Types 4 to 6
with or without failure in conservative treatment
can be treated operatively.2 Operative treatments
include xation across the ACJ with Kirschner wires
(Phemister technique8) or a hook plate,9 xation of the
clavicle to the coracoid process with extra-articular
techniques (Bosworth screw xation10), transfer of
the coracoacromial ligament to reconstruct the CC
ligament (Weaver-Dunn procedure11), and use of
prosthetic materials (non-absorbable sutures around
the coracoid,12,13 suture anchors,14 and CC screw15)
to augment the ligament transfer or to reconstruct
the CC ligament (the TightRope16 [Arthrex, USA],
and the Lockdown17 [Lockdown Medical, Reddich,
UK]). The Lockdown prosthetic ligament is a double
braided polyester mesh with loops at either end (Fig.
2). It has been used for revision of the failed Weaver-
Dunn procedure, augmentation of the Weaver-
Dunn procedure, and stabilisation of the disrupted
ACJ.17–20 This study reports outcomes of 21 men who
underwent stabilisation for the disrupted ACJ using
the Lockdown polyester ligament.
MATERIALS AND METHODS
Between 2005 and 2011, 21 consecutive male patients
aged 23 to 76 (mean, 43) years underwent stabilisation
for the disrupted ACJ of Rockwood type 3 (n=12),
type 4 (n=1), and type 5 (n=8) using the Lockdown
prosthetic ligament. Patients with type 3 ACJ injury
had rst undergone 3 months of conservative
treatment and physiotherapy; one of these patients
opted for surgery after one month. Two patients with
type 5 injury had delayed surgery; one had delayed
referral and another opted to avoid surgery initially.
Patients were placed in the beach-chair position,
and a vertical (shoulder strap) incision was made
over the clavicle. The periosteum was split and the
lateral 1 cm of the clavicle excised.21 The clavicle was
reduced, and the measuring guide was passed around
Figure 1 The Rockwood type 5 acromioclavicular joint
disruption of the left shoulder. Figure 2 The Lockdown prosthetic ligament is a double
braided polyester mesh with loops at either end.

Vol. 23 No. 2, August 2015
Stabilisation for the disrupted acromioclavicular joint using a braided polyester prosthetic ligament
225
the coracoid process from medial to lateral, using the
blunt-ended curved trochar. The appropriate-size
prosthetic ligament was passed around the coracoid
process. The soft loop was tightened around the
base, and the hard loop was looped over the clavicle
from posterior to anterior and xed with a 3.5-mm
bicortical screw with a washer (Fig. 3). Appropriate
tension was applied through the loop to reduce the
clavicle, with a slight over-correction (2–3 mm) of the
clavicle position relative to the acromion. The wound
was then closed in layers.
The postoperative protocol was standardised and
involved 4 weeks of immobilisation in a Polysling,
followed by physiotherapist-guided mobilisation,
with an aim to restart light activities at 8 weeks and
return to sports at 12 weeks.
Functional outcomes were assessed using the
Constant Score22 and the Oxford Shoulder Score.23
The isometric abduction power was assessed using
an electronic spring balance, with the arm held
in 90º of abduction in the scapular plane. Scores
were compared to that of the contralateral side. An
individualised relative Constant Score was calculated
after adjusting for the contralateral side score.
Patient satisfaction was assessed by asking patients
whether they would undergo the procedure again.
Radiographs were assessed for evidence of fracture,
loosening, or redislocation. Redislocation was dened
as a vertical displacement of >50% at the ACJ.
results
The mean time from injury to surgery was 6.8 (range,
0–19) months. The mean follow-up duration was 30
(range, 7–67) months. The mean Constant Score was
86.8 (range, 62–100), and the mean individualised
Constant Score was 88.5 (range, 68–100). The mean
Oxford Shoulder Score was 43.1 (range, 28–48). The
mean abduction power of the operated side was 82%
(range, 31%–97%) that of the normal side (Table 1).
20 patients were satised with the procedure.
One patient was dissatised who developed
scapulothoracic bursitis. One patient required
arthroscopic subacromial decompression for
impingement. One patient sustained a redislocation
following a fall at 6 weeks and declined further
surgery. No patient had wound infection or
clavicular/coracoid process fracture, or required
implant removal for irritation.
discussion
Most ACJ dislocations can be treated conservatively
with good outcomes.7 Surgery is indicated for more
severe disruptions (Rockwood types 4 to 6) and
failed conservative management.5 Patients with high
physical demand jobs or jobs that require overhead
work, or athletes or soldiers are suitable for early
reconstruction for type 3 injuries.24,25 There are various
methods of surgical stabilisation for ACJ disruption
(Table 2). Fixation across the ACJ with a hook plate
may result in impingement or require implant
removal.9 The Weaver-Dunn procedure (transfer of
the coracoacromial ligament to reconstruct the CC
ligament) may not provide sufcient stability, as
the coracoacromial ligament only provides 30% of
the strength of the intact CC ligament.26 A CC screw
improves strength and stiffness of the construct,15,26,27
but is associated with coracoid fracture, screw cut-
out, and screw removal. Other methods include
coronoid cerclage sutures and suture anchors.12,14
Sacrice of the coracoacromial ligament for transfer
is associated with increased instability of the
glenohumeral joint.28,29 The coracoacromial ligament
acts as a buffer between the acromion and the rotator
Figure 3 (a) Rupture of the coracoclavicular ligaments, and
(b) reduction of the acromioclavicular joint and fixation with
the Lockdown prosthetic ligament.
(a)
(b)

226 J Wright et al. Journal of Orthopaedic Surgery
Table 1
Patient characteristics and outcomes
Sex/
age
(years)
Injured
side
Rock-
wood
type
Initial
manage-
ment
Time from
injury to
surgery
(months)
Follow-
up
(months)
Postop
Oxford
Shoulder
Score
Postop Constant Score Postop abduction
strength (kg)
Postop
strength
(% of
normal)
Injured
side
Normal
side
Indivi-
dualised
Injured
side
Normal
side
M/63 Left 3 Sling 3 18 46 82 98 83.7 8.24 10.5 78.5
M/64 Left 3 Sling 18 41 41 80 100 80 5.76 7.5 76.8
M/30 Left 5 Sling 1 32 47 90 98 91.8 9.83 10.19 96.5
M/48 Right 5 Sling 7 16 32 62 90 68.9 6.52 11.33 57.5
M/59 Right 3 Sling 1 53 48 90 100 90 10.62 12 88.5
M/66 Left 5 Sling 0 42 47 92 100 92 7.84 9.18 85
M/39 Left 5 Sling 15 41 28 68 100 68 6.73 9.94 67.7
M/76 Left 4 Sling 0 40 47 87 92 94.6 5.78 7.16 80.7
M/43 Left 5 Sling 1 13 45 95 100 95 11.69 12.3 95
M/41 Left 5 Sling 11 7 40 81 90 90 6.24 8.5 73.4
M/52 Left 3 Sling 6 36 43 90 100 90 9.03 11.2 80.6
M/44 Right 3 Sling 6 29 30 70 95 73.7 3.64 11.64 31.3
M/23 Left 3 Sling 5 21 44 90 100 83.7 9.48 11.8 80.3
M/51 Left 5 Sling 4 7 45 90 100 90 10.9 11.7 93.2
M/27 Left 3 Sling 17 67 45 95 100 95 10.4 11.2 92.9
M/43 Left 3 Sling 3 13 46 93 100 93 10.51 11.5 91.4
M/27 Left 3 Sling 6 23 44 87 100 87 10.8 11.6 93.1
M/26 Left 3 Sling 19 53 48 100 100 100 14.1 15 94
M/30 Right 5 Sling 1 13 46 91 100 91 11.5 12.6 91.3
M/27 Left 3 Sling 10 42 47 95 100 95 13.9 15 92.7
M/26 Left 3 Sling 9 21 46 95 100 95 12.6 13.3 94.7
Technique Advantages Disadvantages
Weaver-Dunn
procedure Widely used Sacrifice of the coracoacromial ligament; lower
strength and stiffness than native ligament; may
require augmentation
Clavicle hook plate Strong construct Plate impingement may necessitate plate removal
Bosworth screw Low cost, readily available Bicortical fixation; risk of coracoid fracture or screw
loosening or breakage; may require screw removal
TightRope No sacrifice of the coracoacromial ligament Risk of coracoid fracture or soft tissue irritation
Lockdown prosthetic
ligament No sacrifice of the coracoacromial ligament;
enables soft-tissue ingrowth; good tensile strength Soft tissue irritation may necessitate screw removal
Table 2
Comparison of various acromioclavicular joint reconstruction techniques
cuff; the risk of cuff pathology may theoretically
increase following its removal.30 Use of a prosthetic
ligament avoids disruption of the coracoacromial
arch and is useful when the coracoacromial ligament
is decient or unavailable (in revision surgery).
Stabilisation with CC cerclage sutures or suture
anchors with polyethylene or polydioxanone has
achieved comparable strength to that of the native
CC ligament in cadaveric testing.12,14,26 Transfer of
the coracoacromial ligament without augmentation
results in the weakest strength and stiffness,
compared to other surgical options. The stiffness
of the Bosworth screw construct is similar to native
ligaments when xation is bicortical.26 The strength
of TightRope is comparable to that of the CC cerclage
sutures or suture anchors. The tensile strength of the
Lockdown prosthetic ligament is greater than both
the native CC ligament and the TightRope.31
The success rates for ACJ reconstruction have
been around 90%.2,11,13,27 For late reconstruction,
the rate is about 78%.13,27 The Lockdown prosthetic
ligament has been used in conjunction with the

Vol. 23 No. 2, August 2015
Stabilisation for the disrupted acromioclavicular joint using a braided polyester prosthetic ligament
227
Weaver-Dunn procedure.18 The Lockdown prosthetic
ligament encourages soft tissue ingrowth17 and thus
is thought to prevent late failure. There is no loss of
reduction after screw removal at a minimum of 9
months, owing to soft tissue ingrowth.17,20
The Constant Score may be biased when used in
a heterogeneous group, in particular given the high
weighting for the strength component.32,33 To correct
this bias, the relative Constant Score to account for
age is used.34 In our study, the strength and Constant
Score of the affected side were compared to those
of the non-affected side. This gave a measure of
proportional strength and an individualised Constant
Score, which is a more reliable measure of shoulder
function in heterogeneous groups.33
One limitation of this study was the potential
for observer bias, as the observer involved in clinical
assessment also involved in the operative procedure.
In addition, preoperative function was not assessed
using the same assessment scales, and thus
improvement in functional scores was not known.
Further randomised controlled studies are needed
to demonstrate superiority of one surgery modality
over another.
conclusion
The Lockdown prosthetic ligament achieved good
outcome for patients undergoing stabilisation for the
disrupted ACJ.
disclosure
No conicts of interest were declared by the authors.
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