Tuesday, December 24, 2013

Pulled elbow & dislocation of radial head at elbow

Traumatic disruption of radio-humeral architecture may take many forms & a cause of lateral elbow pain with elbow stiffness. Subluxation & dislocation occur at this joint without fracture. We are herewith presenting a small review of pulled elbow in children & radial dislocation in adults. The purpose of doing so is to present the clinician to better identify these seemingly equal entities.

Pulled elbow:
It is also known as nursemaid's elbow. It is a common injury in young children. It is considered a minor condition in medicine but cause mush distress to parents of a child.
It results from a sudden longitudinal traumatic pull on pronated and extended forearm, usually by an adult or taller person. This sudden pull pulls the radius through the annular ligament, resulting in subluxation (partial dislocation) of the radial head.
The child experiences sudden acute pain and loss of function in the affected arm.

It appears to be infrequently recognized or diagnosed. Differential diagnosis of traumatic radial head subluxation from traumatic radial head dislocation, congenital radial head dislocation, brachial plexus palsy and "invisible" elbow fractures should be considered. Congenital radial head dislocation is the most common congenital elbow abnormality. Patients generally remain asymptomatic until adolescence and, at that time, may benefit from radial head resection. Open reduction and ligament reconstruction may offer advantages over late radial head resection if performed before the age of 2 years.

Variants of pulled elbow:
It is postulated here that there are two types of traumatic rotary radial head subluxation in pronation, the simple type and the lateral type. Careful analysis of AP view of elbow reveals the change of the shape and position of the radial tuberosity indicating the simple type, or concommitant with lateral displacement of the radial head on the ulna indicating the lateral type.

Treatment procedure:
Pulled elbow is usually treated by manual reduction of the subluxed radial head. Various manoeuvres can be applied. Flexion & supination is believed to be common method employed however few authorities recommend hyperpronation. Most textbooks recommend supination of the forearm, as opposed to pronation and other approaches. It is unclear which manoeuvre is most successful.
According to a Cochrane reviw (2009) pronation method might be more effective and less painful than the supination method for manipulating pulled elbow in young children.
However premanipulative roentgenograms are compared with postmanipulative roentgenograms in such cases to check repositioning.

Dislocation cases:
In closed reduction followed by plaster cast immobilisation for 4 weeks give a good result. In neglected cases where reduction is delayed neocapsule is believed to form hence even arthrography is therefore of little help to differentiate a long standing traumatic dislocation from a congenital dislocation. Various authors prefer & avoid open reduction, which carries a risk of joint stiffness, it is unnecessary to mention old unreduced dislocations cannot be reduced by manipulation. 

Adult cases of dislocation of radial head: 

In adults, isolated radial head dislocation is an extremely rare injury. Isolated traumatic dislocation can be either anterior or posterior. The mechanism leading to an isolated radial dislocation has been variously described. Most authors describe an indirect mechanism. The proximal radioulnar joint is most stable in supination: in this position, the contact between radius and ulna is maximal and the interosseous membrane, the annular ligament, and the anterior fibres of the quadrate ligament are all taut, thus drawing the radial head snugly against its notch in the ulna. Cadaveric studies have shown that posterior dislocation of the radial head cannot occur without the rupture of the annular ligament; in addition, partial tear of the quadrate ligament and the proximal interosseous membrane takes place.
The speculated the mechanism to be a hyperextension of the elbow with forearm in prone position leads to a posterior dislocation of the radial head.

Posterior dislocation of radial head: only few more than 20 cases are described in medical literature but there are no guidelines for treatment. An inability to pronate/supinate while able to flex the elbow should suggest posterior radial head dislocation. There is swelling obvious on the lateral and posterior aspect of the elbow. The elbow is held in flexion and partial supination. Tenderness is present laterally at the elbow, and the radial head is palpable posteriorly. There is no swelling or tenderness over the ulna.

Treatment approach in posterior dislocation: Under general anesthesia, gentle traction, pronation, and direct pressure over the radial head is used to reduce the dislocation. Postreduction, the elbow is generally stable. Immobilization is done in a long-arm cast for 4 weeks in either flexion (110 degres) & supination or uncommonly flexion & pronation. Patient generally recovers complete range of motion.
The diagnosis may be easily missed on radiographs and, therefore, require a high index of suspicion. Authors have reported isolated anterior dislocation of the radial head in young woman without functional disorders. Early reduction is important in order to avoid the necessity for excision of the head of radius and its attendant complications.

If missed or neglected, an open reduction must to be done with either an annular ligament reconstruction or a radial head excision; in these conditions, the results were poor with a restriction of forearm supination and pronation and significant risk of degenerative arthritis of the elbow and the distal radioulnar joints. Closed reduction of an elbow dislocation is unlikely to be successful if attempted later than 21 days after the injury. The results are acceptable if open reduction is undertaken within 3 months of the injury, but after 6 months the results are disappointing and arthroplasty is an alternative.

1. Krul M et al Cochrane Database Syst Rev. 2012 Jan 18;1:CD007759. doi: 10.1002/14651858.CD007759.pub3. (Manipulative interventions for reducing pulled elbow in young children.)
2. Woo CC; J Manipulative Physiol Ther. 1987 Aug;10(4):191-200. (Traumatic radial head subluxation in young children: a case report and literature review.)
.3. Obert L et al; Chir Main. 2003 Aug;22(4):216-9. (Isolated traumatic luxation of the radial head in adults: report of a case and review of the literature.)
4. Damak B et al; Acta Orthop Belg. 1998 Dec;64(4):413-7. (Isolated traumatic anterior dislocation of the radial head).
5. Bruce C et al; J Trauma. 1993 Dec;35(6):962-5. (Unreduced dislocation of the elbow: case report and review of the literature.)
6. Sachar K et al; Hand Clin. 1998 Feb;14(1):39-47. (Congenital radial head dislocations.)
7. Koulali-Idrissi K et al; Chir Main. 2005 Apr;24(2):103-5. [Isolated dislocation of the radial head in an adult (case report and literature review)].
8. J Emerg Trauma Shock. 2010 Oct;3(4):422-4. doi: 10.4103/0974-2700.70767. Isolated, traumatic posterior dislocation of the radial head in an adult: A new case treated conservatively.