Annular Ligament

Attachment

annular ligament

It runs around the radial head form the anterior and the posterior margin o the radial notch, to approximate the radial head to he radial notch and enclose the radial circumference. It encircles 80% o the radial head and unctions to maintain the relationship between the head o the radius and the humerus and ulna. The external surface of the ligament receives attachments from the elbow capsule, the radial collateral ligament, and the supinator muscle.[1]

function

  • Holding the proximal radius against the ulna as it fits strongly around the radial head,
  • It permits for free rotation of radial head as it's internal surface is lined with cartilage.

clinical significance

A strenuous pull on the forearm through the hand can cause the radial head to slip through the distal end of the annular ligament. Young children are particularly susceptible to this “pulled-elbow” syndrome because of ligamentous laxity, an unossified radial head, relative reduced strength and slowed reflexes, and the increased likelihood of others forcefully pulling on their arms—such as a parent, or even a pet dog. One of the best ways to prevent this dislocation is to explain to parents how a sharp pull on the child’s hand can cause such a dislocation.

Assessment

There may be a history of the child being jerked by the arm and subsequently complaining of pain and inability to use the arm. The arm is held more or less immobile with the elbow fully extended and the forearm pronated; any attempt to supinate the forearm is resisted. The diagnosis is essentially clinical, although radiographs are usually obtained to exclude a fracture.

treatment

closed reduction of annular ligament subluxation

for the majority of cases

indications

  • must be certain no fracture is present prior to any manipulation

open reduction rarely required

indications

  • for chronic, symptomatic subluxations that cannot be reduced

Closed reduction of annular ligament subluxation   

  • supination technique  
    • while holding the arm supinated the elbow is then maximally flexed
    • the physician’s thumb applies pressure over the radial head and a palpable click is often heard with reduction of the radial head
  • hyper pronation technique
    • involves hyper pronation of the forearm while in the flexed position 
  • followup
    • child should begin to use the arm within minutes after reduction
    • immobilization is unnecessary after the first episode

.

[2]


References

  1. Bozkurt M, Acar H, Apaydin N, Leblebicioglu G, Elhan A, Tekdemir İ et al. The Annular Ligament. The American Journal of Sports Medicine. 2005;33(1):114-118.
  2. Nursemaid's Elbow. Larry Mellick available from:https://www.youtube.com/watch?v=tJb5rGOFiTY