The document discusses injuries to the acromioclavicular (AC) joint. It provides details on the anatomy and biomechanics of the AC joint and surrounding ligaments. Common mechanisms of injury include falling on an outstretched arm or direct force to the lateral shoulder. Injuries are classified using the Rockwood system from Type I to VI based on the degree of ligament disruption and bone displacement. Treatment options include nonoperative measures for lower grades and surgery for higher grades or failed nonoperative treatment. Surgical techniques and associated conditions are also reviewed.

1. Acromioclavicular Joint Injuries
Presenter- Dr Suman Subedi
Moderator- Dr Amrit Shrestha

2. Contents
• Applied anatomy
• Overview
• Mechanism of injury
• Classification
• Clinical presentation
• Imaging
• Treatment options
• Surgical techniques
• Associated conditions

3. Applied Anatomy
• A plane synovial joint, located between medial margin
of acromion and lateral end of clavicle
• Within the AC joint, there is a fibro cartilaginous disc

5. Acromioclavicular Ligaments
• Consists of anterior, posterior, superior, and inferior
ligaments, surround the AC joint
• Stabilize the joint in horizontal plane
• Superior AC ligament- strongest of capsular ligaments,
blend with fibers of the deltoid and trapezius muscles
adding stability to AC joint.

6. Coracoclavicular Ligament
• Very strong ligament from outer inferior surface of
clavicle to base of the coracoid process of scapula.
• Two components—conoid and trapezoid ligaments
• Vertical stability of AC joint

7. • The only connection between the upper extremity
and the axial skeleton is through the clavicular
articulations at the AC and SC joints.
• SC ligaments support clavicles suspended away from
the body
• CC ligament suspend upper extremities from distal
clavicles

8. • CC ligament helps to
couple glenohumeral
abduction/flexion to
scapular rotation on thorax
during overhead elevation
• Clavicle rotates around 40-
50 degrees during full
overhead elevation--
simultaneous scapular
rotation and AC joint
motion

9. Overview
• Injuries to either AC or SC joints can result in a wide
range of shoulder dysfunction.
• Both can be injured by similar mechanisms, present
with overlapping clinical complaints, and in some
cases result in injury to both locations
• Acromioclavicular injures are more common, and
sternoclavicular injuries are rare

10. Risk groups
• often occur in male patients less than 30 years of age
• associated with contact sports or athletic activity in which direct blow
to lateral aspect of shoulder occurs.
• The contact or collision athlete represents a “high-risk” individual
(football, rugby, and hockey)
• AC joint injuries accounted for 4.5% of all injuries (and 32% of all
shoulder injuries) in a population of NCAA football players followed
for 5 years. Of the 748 injuries to the AC joint recorded, the vast
majority (96%) were “low-grade” injuries, classified as type I or II
sprains

11. Mechanisms of Injury
• Falling on an outstretched arm, locked in extension at
the elbow, can drive humeral head superiorly into
acromion--low-grade AC joint injuries
• A medially directed force to lateral shoulder that
drives acromion into and underneath the distal
clavicle(when getting checked into the boards during
a hockey game)- higher degrees of injury and
subsequently more displacement.

12. • More commonly described pattern- falling or being
tackled onto lateral aspect of the shoulder with the arm
in an adducted position which produces a compressive
(medial) and shear (vertical) force across the joint-
typically produces higher degree of displacement enough
to tear both AC and CC ligaments.

13. • The injury force which drives acromion medially and downward
produces a progressive injury pattern; first disruption of AC ligaments,
followed by disruption of CC ligaments, and finally disruption of fascia
overlying the clavicle that connects deltoid and trapezius muscle
attachments.
• Complete AC dislocation- the upper extremity has lost its suspensory
support from clavicle and scapula- inferior displacement of the
shoulder secondary to forces of gravity.

14. Nontraumatic or Chronic Overuse
• AC joint arthrosis—weight lifting, laborer, repetitive overhead activity
• Repetitive low-grade AC joint injuries
• Medical cause: rheumatoid arthritis, hyperparathyroidism,
scleroderma

15. Clinical presentation
• Young-aged male
• Contact or collision athlete
• H/O direct trauma
• Clinical deformity, focal tenderness and swelling
• Commonly the patient describes pain originating from the anterior-
superior aspect of the shoulder

16. Diagnosis
• Examination should be in sitting or standing w/o support for the injured
arm
• Check for tenderness to palpation at the AC joint and the CC interspace
• If patient can tolerate check joint for stability
• Check to see if reducible
• Examine SC joint as well
• Neurologic exam to r/o brachial plexus injury

18. Paxinas test
Active compression test of O’Brien

19. Clinical triad
• point tenderness at the AC joint,
• pain exacerbation with cross-arm adduction, and
• relief of symptoms by injection of local anesthetic
agent confirm injury to the AC joint.

20. Imaging
• Good-quality radiographs of the AC joint require one-
third to one-half the beam penetration to image the
glenohumeral joint.
• Radiographs of the AC joint taken using routine
shoulder technique will be overpenetrated (i.e.dark),
and small fractures may be overlooked.
Therefore,specifically requested to take radiographs
of “AC joint” rather than the “shoulder.”

21. Radiographic Normal Joints
• Width and configuration of AC joint in coronal plane
may vary significantly from individual to individual. So,
a normal variant should not be mistaken as an injury.
• Normal width of AC joint in coronal plane is 1 to 3 mm.
AC joint space diminishes with increasing age (0.5 mm
in older than 60 years is conceivably normal). Joint
space of greater than 7 mm in men and 6 mm in
women is pathologic.
• Average CC distance 1.1 to 1.3 cm. An increase in CC
distance of 50% over normal side signifies Complete AC
dislocation (has been seen with as little as 25% increase
in CC distance).

22. Zanca View
• Beam placed 10
degrees cephalad
• Obtained using soft
tissue technique in
which voltage is cut
into half
• quantifying CC
distance, and
percentage
displacement of distal
clavicle above
acromion.

23. • AP weighted
stress view
(with wt.10-
20 lb) can be
used in
suspected
injury

24. • Axillary view: Determine
anteroposterior position
of distal clavicle in relation
to acromion

26. West point view

27. Biplanar Instability/Displacement
Vertical translation Horizontal

28. Tossy-
Rockwood
Classification

29. Type of Injury Clinical Features Radiological Features
Type I  minimal to moderate tenderness to palpation over the AC joint
 mild swelling over the AC joint
 minimal pain with arm movements
 respond very well to local anesthetic/ corticosteroid injections
No widening,separation or
deformity
Type II • moderate to severe tenderness with palpation of the joint
• Distal end of clavicle slightly superior to acromion
• Adduction motion of the shoulder produces pain in the AC joint
• Difficulty sleeping
• AC horizontal Instability
• Tenderness at CC space
<50% width of clavicle
displacement at AC joint
Increased CC distance < 25% of
contralateral
Type III • Upper extremity held adducted in elevated position
• shoulder droop sign
• Clavicle may be prominent enough to tent the skin.
• Moderate pain -any motion of the arm, particularly abduction
• Tenderness at AC joint, CC interspace, and along superior aspect
of lateral clavicle.
• AC joint instability in both the horizontal and vertical planes
• “shrug test” (vs type V)
Distal clavicle Displaced
Increased CC distance 25-100% of
contralateral
May be accompanied by Fracture
coracoid > Stryker View

30. Type of Injury Clinical Features Radiological Features
Type IV • All clinical findings of type III injury.
• clavicle is translated posteriorly compared with uninjured
shoulder may be “buttonholed” through trapezius muscle
and tents posterior skin.
• AC joint cannot be reduced manually
• Examine SC joint “bipolar” or “floating clavicle” injuries,
Best Observed in Axillary View
Lateral clavicle displaced posterior through
trapezius
Type V • Distal end of clavicle grossly superiorly displaced, tenting
the skin
• Downward Displacement of Upper Extremity
• More Pain than Type III secondary to more soft tissue
disruption.
• Shoulder musculature becomes weak secondary to disuse
or as part of the injury pattern-scapular dyskinesis
Zanca View
Increased CC distance > 100% of contralateral
Type VI • superior aspect of shoulder has flat appearance
• acromion is prominent
• associated fractures of clavicle,upper ribs or injury to upper
roots of brachial plexus
• Mechanism :Severe Hyperabduction and ER + retraction of
scapula
Subacromial type - decreased CC distance,
distal clavicle in subacromial location.
Subcoracoid type - reversed CC distance,
clavicle displaced inferior to coracoid process

34. • Children and adolescents may
sustain a variant of complete
AC dislocation (most often
Salter–Harris type I or II)
• Radiographs reveal
displacement of distal
clavicular metaphysis
superiorly (through a dorsal
rent in periosteal sleeve) with
increase in CC interspace.
Epiphysis and intact AC joint
remain in their anatomic
locations

35. Treatment goals
• Pain-free shoulder movement in a range-of-motion arc approaching
normal
• Unimpaired daily activities

36. Treatment Options
Nonoperative Treatment
• Indications-
Type I,II,III AC injuries
• Relative contraindications-
-Chronic symptomatic injury
-Failed nonoperative management, athlete, polytrauma, heavy
laborers

37. During 1st week of treatment
• Immobilization device (Arm slings, adhesive tape strappings, braces
and plaster)-
 To support the weight of upper extremity and reduce the stress
placed upon the injured ligaments
• Ice and analgesics
To reduce pain and inflammation

38. After 1 to 2 weeks
• Strengthening exercises commenced with particular focus on
periscapular muscles that are important to shoulder
biomechanics.
• Heavy stresses, lifting, and contact sports should be delayed
until there is full range of motion and no pain to joint palpation.
This process can take up to 2 to 4 weeks
• Athletes who desire an earlier return to sports should be
encouraged to use protective padding over the AC joint. An
earlier return to sports that sustains a second injury to the AC
joint, prior to complete ligament healing, can change a partially
subluxated AC joint into a complete AC dislocation. Given this
possible sequela, a forewarning must be provided to all athletes
wishing to return to play at an earlier time. This decision is a
balance between the desire to return to play early and the risk
of reinjury.

39. DISADVANTAGES OF NON OPERATIVE
TREATMENT
• SKIN PRESSURE AND ULCERATION
• RECURRENCE OF DEFORMITY
• WEARING A BRACE FOR LONG TIME(8
WEEKS)
• POOR PATIENT COOPERATION
• INTERFERENCE WITH DAILY ACTIVITIES
• LOSS OF SHOULDER AND ELBOW MOTION
• SOFT TISSUE CALCIFICATIONS
• LATE ACROMIOCLAVICULAR ARTHRITIS
• LATE MUSCULAR ATROPHY,FATIGUE AND
WEAKNESS.

40. Type III- operative or nonoperative ?
• In prospective randomized studies between operative and
nonoperative treatment of type III AC joint injuries, patients treated
nonoperatively demonstrated a quicker return of function and
sustained fewer complications than patients treated operatively.
• Patients treated conservatively returned to work on average 2.1
weeks from injury and the strength and ROM of the injured shoulder
were comparable to the contralateral uninjured shoulder with a
mean follow-up of 2.6 years (Wojtys and Nelson)
• Operatively treated AC injuries showed a significantly higher
incidence of osteoarthritis and CC ligament ossification
• A proportion of conservatively treated patients will have persistent
pain and inability to return to their sport or job. Subsequent surgical
stabilization has allowed return to sport or work in such cases

41. Reasons for lower-grade AC joint injuries being
symptomatic –
• posttraumatic arthritis
• posttraumatic osteolysis of the distal clavicle,
• recurrent AP subluxation,
• torn capsular ligaments trapped within the joint,
• loose pieces of articular cartilage,
• detached intra-articular meniscus or associated intra-
articular fracture fragment.

42. Chronic Acromioclavicular Injuries
• Chronic pain after type I and II injuries- NSAIDS, avoidance of painful
activity or positions, and intra-articular injection with corticosteroid
• Type I-
Operative excision of distal clavicle (limited to less than 10 mm )-open or
arthroscopic
• Type II-
Distal clavicle excision + AC capsular reconstruction or coracoacromial
ligament transfer
• Chronic pain and instability after types III, IV, and V- Distal clavicle
excision + Transfer of acromial attachment of coracoacromial ligament to
the resected surface of distal clavicle and concurrent CC stabilization

43. Operative Treatment
Indications -
• Patients (types I,II,III) who have failed a minimum 6
weeks of shoulder stabilization–directed physical
therapy (delayed surgical reconstruction using a
tendon graft)
• Active healthy patients with complete AC joint injuries
(types IV, V, and VI)- significant morbidity associated
with the injury pattern- persistently dislocated,
unstable AC joint, with change in scapular kinematics,
and shoulder dysfunction.
• Fracture of coracoid extending intra-articularly into
glenoid (5 mm or more of glenoid displacement )

44. • Fixation across AC joint
• Fixation between coracoid and
clavicle
• Ligament reconstruction
• Distal clavicle excision

45. ANY SURGICAL PROCEDURE FOR AC JOINT
DISLOCATION SHOULD FULFILL THREE REQUIREMENTS
• AC JOINT MUST BE EXPOSED AND DEBRIDED
• CC AND AC LIGAMENTS MUST BE
REPAIRED OR RECONSTRUCTED
• STABLE REDUCTION OF THE AC JOINT MUST BE
OBTAINED
Achievingthese three goals , no matter how the joint is
fixed , should give acceptable results.

46. DISADVANTAGES OF SURGICAL
MANAGEMENT
• INFECTION
• HEMATOMA FORMATION
• ANAESTHETIC RISK
• SCAR FORMATION
• RECURRENCE OF DEFORMITY
• METAL BREAKAGE,
LOOSENING,MIGRATION
• SECOND SURGERY FOR REMOVAL
• BREAKAGE OR LOOSENING OF
SUTURES
• EROSION OR FRACTURE OF DISTAL
CLAVICLE

47. Acromioclavicular Fixation
• Pin fixation
• Has been
abandoned
since reports of
rare pin
migration
– Heart, Lung,
Great vessels

49. Acromioclavicular fixation
• Hook Plate
• Only used for
acute injury
• Requires
subsequent
surgery for removal

50. Fixation between coracoid and clavicle
• Bosworth popularized the use of a screw for fixation
of the clavicle to the coracoid
• This technique initially did not include
recommendation for repair or reconstruction of the CC
ligaments
• Today the use of screws and suture loops has been
described alone and in combo with ligament
reconstruction
• Placement of synthetic loops between the coracoid and
clavicle can be done arthroscopically, main advantage:
doesn’t require staged screw removal

51. • Bosworth “screw suspension” technique

52. Repair+Tightrope augmentation

53. Ligament reconstruction
• Weaver and Dunn were the 1st to describe transfer for the
native CA ligament to reestablish AC joint stability
• Their technique described excision of the distal clavicle with this
ligament transfer
• Construct can be augmented with a suture loop for protection until
the
transferred ligament heals
Open or Arthroscopy

54. Modified Weaver and Dunn Procedure

55. Anatomic Ligament Reconstruction
• Alternative technique is use of semitendinosus autograft for
reconstruction
– Loop around or fix into coracoid, then fix through two separate clavicle
bone tunnels to approximate normal anatomic location of CC
ligaments
• Recent biomechanical studies have demonstrated the superiority
of this
construct

56. Anatomic Coracoclavicular Ligament Reconstruction
• ACCR technique attempts to restore biomechanics of
AC joint complex as treatment for painful or unstable
dislocations
• Rationale- to reconstruct both CC ligaments by
anatomically fixing a tendon graft in two clavicle
tunnels placed in the anatomic insertion site of conoid
and trapezoid ligaments.
• In addition, AC ligaments are reconstructed with the
remaining limb of the graft exiting the more lateral
trapezoid tunnel.

57. ACCR technique: patient positioning
• Far lateral position with shoulder free to extend, small
scapula bump along medial scapula border, and head
position extended and rotated away from operative side.

58. ACCR-Steps
• Vertical incision centered on clavicle (starting from
posterior clavicle to just medial of coracoid process
)approx 3.5 cm medial to AC joint.
• Subperiosteal flaps raised to ensure that trapezius and
deltoid attachments are elevated off. Tagging stitches can
be placed to aid in tight closure of this layer during
closure.

59. • Conoid tunnel position marked at least 45 mm from
distal clavicle
• Trapezoid tunnel position marked with at least 25 mm
of bone bridge between tunnels
• Tunnels drilled

60. • Graft passed through
tunnel,beneath coracoid
• Interference fixation with
PEEK screws
(polyetheretherketone)
• Continue brace for 8 weeks
• Strengthening exercises
from 12 weeks

61. • Graft options- semitendinosus allograft/autograft, Anterior tibialis
allograft.
• Semi-tendinosus allograft preferred -simplification of patient
positioning, no donor site morbidity, decreased operative time,
consistency in graft tissue size
• The minimal length needed to ensure graft available for AC ligament
reconstruction approx 110 mm.

62. Associated conditions
• Glenohumeral Intra-Articular Pathology
• Fractures
• Brachial Plexus Abnormalities
• Coracoclavicular Ossification
• Osteolysis of the Distal Clavicle
• Scapulothoracic Dissociation

63. • Glenohumeral Intra-Articular Pathology Pauly et al. noted a 15%
incidence of intra-articular pathology, SLAP and PASTA(Partial articular
supraspinatus tendon avulsion) lesions, in their series of 40
consecutive patients undergoing arthroscopic-assisted reconstruction
of grade III to V AC joint dislocations

64. Fractures
• lateral clavicle fracture
• base or neck of coracoid process fracture
• concomitant injury to medial clavicular epiphysis (less than 30 years
of age)
• Fracture of midshaft of clavicle with either anterior or posterior
subluxation/dislocation of SC joint (uncommon)

65. Secondary osteoarthritis
• late complication
• usually be managed conservatively,
• If pain is marked, the outer 2 cm of clavicle can be excised.

66. Case
• 30 yrs/ F with history of fall from
scotter sustaining injury to left
shoulder

68. • 64 Y/M with AC joint injury Type 3

69. Rockwood Classification
Type AC
ligament
CC ligament Exam Radiographs Reducibility Treatment
Type I Sprain Normal AC
tenderness
No AC
instability
Normal Reducible Sling
Type Il Torn Sprain AC horizontal
instability
AC joint disrupted Increased CC
distance < 25% of contralateral
Reducible Sling
Type III Torn Torn AC joint disrupted Increased CC
distance 25-100% of contralateral
Reducible Controversial
IIIA AC vertical
instability No
horizontal
stability
IIIB AC vertical
instability
Horizontal
instability

70. Type AC ligament CC ligament Exam Radiographs Reducibility Treatment
Type IV Torn Torn Skin tenting
Posterior
fullness
Lateral clavicle
displaced
posterior
through
trapezius on the
axillary lateral
XR
Not reducible Surgery
Type V Torn Torn Severe shoulder
droop, does not
improve with
shrug
. Increased CC
distance > 100%
of contralateral
Not reducible Surgery
Type VI Torn Torn Rare; Associated
injuries;
paresthesias
. Inferior
dislocation of
lateral clavicle,
lying either in
subacromial or
subcoracoid
position
Not reducible Surgery

71. References
• Rockwood and Greens Fractures in Adult, Ninth edition
• Campbell Orthopaedics ,14th edition
• Apley and Solomon’s System of Orthopaedics and Trauma, Tenth
Edition
• https://www.orthobullets.com/shoulder-and-
elbow/3047/acromioclavicular-joint-injury

72. •Thank you