BLOG

Anatomy and biomechanics

• Diarthoidal joint – plane type of synovial joint
• Superior capsule blended with deltoid and trepizius
• supero inferior and antero posterior movents
• Fibrous capsule

Typical features

• Cartilage – fibrocartilage
• Joint partially devided by articular disc.

Ligaments

• AC ligament :
  • horizontal stabilizer
  • Resist 90% of A-P translation and joint distraction
  • Posterior and superior AC capsular ligaments provide greatest stability
  • Clinical importance of distal clavicale resection
• CC ligament :
  • vertical stabilizer
  • Conoid– primary restraint to superior translation
  • Trepizoid resists 75% of AC joint compressionz
•  Fukuda et al.,jbjs 1986; klimkiewicz et al.,jses 1999
  • Conoid– attaches posterior and medial on clavicle
  • 2^ndligament to fail after ac ligament
  • Trepizoid– attaches anterior and lateral on clavicle
  • Movements : ac joint have passive movements with coordination of scapular movements
  • 5 to8 deg of movement present during elevation of arm above 90deg

Mechanism of injury

^Direct

• Most common
• Direct force to acromion with shoulder adducted only
• Acromion is moves inferiorly and medially (clavicle stabilized by sc joint)

Indirect

• Less common
• Out stretched hand
• Typically affects AC ligaments

Order of failure –

• ac ligaments/capsule
• CC ligaments
• Deltotrapezial fascia

Diagnosis

Clinical :

• tenderness over lateral end of clavicle or shouler
• swelling or deformity
• Stability of joint and reducible or not
• Special tests – O Brein‘s active compression test. Paxinos sign cross body addiction test and resisted extension test
• Sc joint and neurological examination

Imaging :

• X ray : AP view Stress view zanca view – specific and sensitive for ac joint Axillary view – ap translation
• Ct/mri– rare suspected other injuries

Classification

• Mainly based on vertical and horizontal instability
• Allman (Allman F L, JBJS (am) 49:774-784, 1967)
• Tossyet al – (Tossy et al, CORR, 28: 111-119, 1963)
• Later modified by Rockwood(In: Fractures in adults, edited by Rockwood, CA, 1341-1414, Lippincott-Raven, 1996)

Management 

Reid et al 2012 – conservative management is the main recommendation for grades 1-3

Conservative management

Gladstone protocol (1997)

 pain relief and protection

Phase 2 – ROM and early isotonic strengthening

Phase 3- advanced strengthening and dynamic AC joint stability strengthening

Phase 4– sports specific training

Rehabilitation

• Early focus is on passive and active ROM
• Once symmetric and painless ROM achieved then progress to isometric shoulder strengthening
• Isotonic strengthening
• Sport specific training
• Return to sports by 2-3months

Surgical management

• For type IV and above
• Methods :
  • Fixation across AC joint
  • Fixation between coracoid and clavicle
  • Ligament repair +/- augmentation or fixation
  • Anatomical Ligament reconstruction
  • Distal clavicle excision

Phemister technique

• • Recently not used alone because of complications
  • Used with other procedures to augment them
  • Complications-
  • Pin breakage and migration
  • Recurrence of lesion

Hook plate

• • Only used for acute cases
  • Requires subsequent removal
  • Osteolysis – 17%
  • Protrusion and irritation of skin

Bosworth technique

Mazzocca et al, AJSM 2007

• • Cadaveric study
  • Distance between lateral end of clavicle to conoid tuberosity : 45mm
  • To trapezoid tuberosity : 25mm

Tight rope

• • Instead of screw using tight rope with endobuttons
  • Used along with the repair of ligaments to augment

Ligament reconstruction

• • Resection of distal clavicle incresar the horizontal translation so it should be graded and determental
  • Intact of distal clavicle decreases the force on postero superior aspect of AC ligaments

• • Results: There were significant increases in AP translation with the cut AC joint capsule, and significant increases in SI translation with the cut CC ligaments (P < 0.0001). Compression significantly decreased translation (P < 0.0001).
  • To conclude
  • Distal clavicle resection is determental but
  • Ac ligament and capule repair or re construction gives good results

Waver Dunn procedure

• • Distal clavicle excision
  • The ca ligament is transferred to the distal clavicle
  • CC ligaments are repaired +/augmentation
  • Repair of deltotrapezial fascia
  • Ac joint not addressed

Mazzocca technique

• • Campell describes
  • Anatomic reconstruction of cc ligaments

Anatomical reconstruction

• Grafts :autigrafs (hamstrings)
• Allografts :
  • LARS
  • SURGILIG
  • RotaLok system
  • Keio Leeds system

LARS

• Braided polyethylenetraphthalate
• 100N tensile strength
• Vascularisation and fibrous ingrowth – type I collagen
• Failure may be due to malposition of tunnels in the clavicle
• Anatomic reconstruction has higher loads of failure 

 Newer techniques

• Gritter and Petersen technique

Complications of ac joint dislocation

• Arthritis
• Cosmetic
• Scapular dyskinesia
• Sick scapula syndrome
• Shoulder weakness and stiffness
• Rotator cuff problems

Sick scapula syndrome

• Scapular malposition
• Inferomedial prominence of scapula
• Coracoid pain and Kinesial abnormalities of scapula