Equis ISSN 2398-2977

Elbow joint: disease - overview

Introduction

• The elbow is an uncommon site for forelimb lameness.
• Cause: direct trauma is the most common cause. 
• Signs: usually sudden onset, moderate to severe, forelimb lameness. 
• Diagnosis: clinical examination and range of ancillary aids including joint anesthesia   Forelimb: joint anesthesia  and radiography   Forelimb: radiography  . 
• Treatment: depends on cause. 
• Prognosis: depends on cause.

Pathogenesis

Etiology

Trauma

• Most common cause of acquired elbow conditions. 
• Fractures: of the olecranon of the ulna are one of the most commonly seen long bone fractures   Ulna: fracture  ; also seen proximal radius   Radius: fracture  . Articular fractures may be comminuted, open, closed, distracted, non-distracted.
• Luxation/subluxation of the elbow joint is uncommon: usually seen with fractures of the olecranon or proximal radius, or separation of the radius and ulna.
• Tearing of collateral ligaments: uncommon; lateral more commonly involved.
• Tearing of the attachments of the biceps brachii muscle from the cranioproximal aspect of the radius. 
• Traumatic synovitis and capsulitis occur following single or repeated episodes of trauma to the elbow joint. It may progress to degenerative joint disease   Musculoskeletal: osteoarthritis (joint disease)  . 
• Subchondral bone stress of the distal humerus in young jumping animals.
• Olecranon bursitis (capped elbow, shoe boil)   Elbow: hygroma  .
• Hematoma   Hematoma  .
• Pressure sores     .

Infectious

• Septic arthritis may occur secondary to trauma, joint penetration    Joint: septic arthritis - adult      Joint: septic arthritis - foal   or via hematogenous spread       .

Multifactorial

• Osteochondrosis in the distal humerus or proximal radius   Bone: osteochondrosis  .
• Osteochondritic lesions of the anconeal process of the ulna.
• Osteoarthritis   Elbow: osteoarthritis  .

Immune-mediated

• Immune-mediated polysynovitis uncommon, but may involve the elbow joint    Joint: immune-mediated polysynovitis  .

Miscellaneous

• Tumors are extremely rare.
• Osseous cyst-like lesions of the elbow joint are uncommon     , typically communicate with the joint, and occur most commonly in the medial proximal radial epiphysis or the distal medial condyle of the humerus   Bone: osseous cyst-like lesions  .

Predisposing factors

• Septic conditions: 
  • Failure of transfer of passive immunity in the foal   Foal: failure of passive transfer (IgG)  , placentitis   Placenta: placentitis  or endometritis   Uterus: endometritis - bacterial  .
  • Poor hygiene.
• Elbow fractures: 
  • Little soft tissue cover to joint.

Pathophysiology

• The elbow joint is the articulation between the humerus, radius and ulna, stabilized by medial and lateral collateral ligaments.
• The joint capsule forms a pouch in the olecranon fossa where it is extremely thin.
• Oblique fibers strengthen the joint capsule cranially.
• The joint capsule blends with the collateral ligaments medially and laterally.
• There is minimal soft tissue cover over the lateral aspect of the elbow joint making it vulnerable to trauma and penetration.
• See Joint: synovial pathobiology   Joint: synovial pathobiology  .

Diagnosis

Treatment

Outcomes