AC Joint Separation

AC Joint Separation
Anatomy: The Acromioclavicular (AC) Joint is one
of four joints that compose the shoulder complex.
The AC joint is formed by the junction of the distal
end of the clavicle and the acromion process of the
scapula, forming a plane style synovial joint. The
AC joint serves as the main articulation that
suspends the upper extremity from the trunk, and it
is at this joint about which the scapula moves. The
AC joint capusle and ligaments surrounding the
joint work together to provide stability and to keep
the clavicle in contact with the acromion process of
the scapula.
The AC joint contains synovial fluid which helps
lubricate the joint which is surrounded by a joint
capsule. There are three ligaments stabilizing the
AC joint; the superior and inferior acromioclavicular
ligmanets and the coracoclavicular ligaments. The
superior acromioclavicular ligament covers the superior portion of the joint, and attaches
the superior distal clavicle and the superior acromion. It is composed of parallel fibers,
which interlace with the aponeuroses of the trapezius and deltoid. The inferior
acromioclavicular ligament is a thinner ligament connecting the inferior portion of the
distal clavical to the acromion. The AC Ligaments serves to reinforce the joint capsule
and prevents posterior translation and posterior axial rotation at the AC joint.
The coracoclavicular ligaments, composed of the conoid and trapezoid ligaments, are
the primary support ligaments of the AC joint. The coracoclavicular ligaments run from
the coracoid process to the underside of the clavicle, near the AC joint. The conoid
ligament is located more medailly as the trapezoid ligament is the lateral portion of the
coracoclavicular ligament.
Causes/Mechanism of Injury: AC joint separation or dislocation is particularly common
in collision sports such as ice hockey, football and rugby, and can also be a problem for
athletes who participate in repetitive movements such as swimming, volleyball and
tennis. The most common mechanism of injury is a fall on the tip of the shoulder or fall
on an outstretched hand. AC dislocations are graded from I to VI. Grading is based
upon the degree of separation of the acromion from the clavicle with weight applied to
the arm. Grade I is a tear or partial tear of the AC ligament alone. Grade II is a complete
dislocation of AC ligament with partial disruption of coracoclavicular ligament. Grade III
is complete disruption of AC and CC ligaments. On plain film the inferior aspect of the
clavicle will be above the superior aspect of the acromion. This can also be assessed
with an MRI scan, which will also demonstrate disruption of the coracoclavicular
ligaments as well as tearing of the joint capsule. Grades IV-VI are complications of
Grade I-III dislocations involving a displacement of the clavicle.
Symptoms: Pain is the most common symptom of a separated shoulder, and is usually
severe at the time of injury. Evidence of traumatic injury to the shoulder, such as
localized swelling and bruising, are also commonly found. The diagnosis of shoulder
separation is often quite apparent from hearing a story that is typical of this injury along
with physical examination. Individuals who have suffered an AC joint separation will
present with a “step down deformity” as the clavical has risen above the level of the
acromion process. An x-ray may be performed to ensure there is no fracture of these
bones. If the diagnosis is unclear, an x-ray while holding a weight in your hand may be
helpful as the weight will accentuate any shoulder joint instability and better show the
effects of the separated shoulder.
Treatment/Management: Grades I and II do not require surgery and heal by
themselves, though physical therapy may recommended. The joint will be very tender
and swollen on examination. Controversy exists as to the effectiveness of surgical
intervention with Grade III separations. Most evidence suggests that patients with type
III shoulder separations do just as well without surgery, and avoid the potential risks of
surgical treatment. These patients return to sports and work faster than patients who
have surgery for this type of injury. High level overhead athletes or laborers may benefit
from the additional stability of surgical intervention. The initial treatment of a separated
shoulder consists of controlling the inflammation, and resting the joint. The inflammation
from a separated shoulder can be controlled with ice placed on the joint every four
hours for a period of 15 minutes. Icing can be done for the first several days until the
swelling around the joint has subsided. A sling to rest the joint can be worn until the
pain has subsided and you can begin some simple exercises. Resting the joint will help
minimize painful symptoms and allow healing to begin. Anti-inflammatory medication
such as Advil or Motrin will also help to minimize the pain and inflammation--check with
your doctor before using these medications. Type IV, V, and VI shoulder separations
almost always require surgery, however these are very uncommon injuries.
Most surgical procedures for treatment of a shoulder separation attempt to reconstruct
the important coracoclavicular ligament, and temporarily hold the clavicle in position
while the reconstructed ligament heals. A commonly performed procedure uses the
nearby coracoacromial ligament, and moves it over to the clavicle. Individuals should
avoid sleeping on either side following AC joint separation. Full PROM should be
achieved by 2-3 weeks following the injury leading into general shoulder strengthening.
ROM and isometric strengthening should be the initial phase of rehabilitation avoiding
elevation above 90 degrees. Progress should then focus on functional strengthening as
tolerated with no pain or swelling with additional scapular strengthening.
Norman
Newcastle
Purcell
2475 Boardwalk
Norman, OK 73069
PH (405) 447-1991
2340 N.W. 32nd
Newcastle, OK 73065
PH (405) 392-3322
2132 N. Green Ave
Purcell, OK 73080
PH (405) 527-1500
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