- Discussion:
- see:
elbow dislocations in children:
- elbow dislocation is the second most common major joint dislocation;
- dislocation is usually closed and posterior;
-
mechanism:
- dislocations of elbow usually result from fall onto extended elbow.
- anatomic morphology of semilunar notch may predispose to elbow
dislocation;
- central angle of semilunar notch is sig large in group of pts who
had dislocation of the elbow compared
to normals;
-
classification:
- dislocations are classified according to direction of dislocation,
namely posterior, posterolateral,
posteromedial,
lateral, medial, or divergent;
- elbow dislocations without fracture are termed "simple." whereas
dislocations with frx are termed
complex;
-
dislocation w/ radial head frx: most common complex dislocation;
-
simple dislocation: pathoanatomy:
- rupture of capsule, rupture of
MCL, lateral ligaments, rupture of flexor pronator mass and less
commonly, injury to brachialis muscle;
- lateral collateral ligament may be the essential lesion in
recurrent or persistent instability following
simple dislocations of the elbow
- rupture of brachial artery has been reported;
- ref:
Classification and evaluation of recurrent instability of the elbow.
-
stability of elbow:
- primary stabilizers
-
MCL is the main stabilizer of the elbow joint (provides 54% valgus
stability, while osseous
articulation provides 33%);
- ulnohumeral articulation
- coronoid: clinical experience suggests 50% intact
coronoid requirement for stability with or
without ligamentous integrity
- olecranon contribution to stability inversely
correlated with resection amount: >30% articular
surface of olecranon needed for stability
- secondary stabilizers
- radiohumeral articulation (most important)
- capsule: greatest role in extension of elbow, insignificant
role (<10%) in flexion
- musculature (dynamic)
- ref: Morrey BF, An KN: Articular and ligamentous contributions
to the stability of the elbow joint.
Am J Sports Med 1983;11:315-319.
- Exam:
- vascular injury:
- closed dislocations are rarely assoc w/ vascular injury, whereas open
&/or ant dislocations are commonly
assoc w/ such
injury;
- in open dislocations,
brachial artery
is disrupted by forcible hyperextension (
median nerve
injury is
commonly associated
with such injuries);
- references:
-
Closed elbow dislocation and brachial artery damage. [Review]
- neuro injury:
-
diff dx:
compartment syndrome: before assuming that a nerve
injury is present consider whether there
is an evolving
compartment
syndrome;
- remember that the pain of the compartment syndrome is
distracted by the more obvious elbow
dislocation;
- these patients often have had conscious sedation, which can
blunt on going pain from a
compartment syndrome;
- after several hours, the acute pain of a compartment syndrome
may diminish (nerve ischemia), after
which it will be difficult to distinguish from a nerve injury;
-
neuropraxia is occurs in 20%, usually involving ulnar or median n (
AIN
branch);
- ulnar nerve palsy may occur up to 14% of adult elbow dislocations,
and the occurance of ulnar nerve
palsy is much higher in
pediatric dislocations w/ an associated medial epicondyle frx;
- most neurologic deficits are transient, but entrapment of median
nerve w/ elbow joint after manipulation
is more common in
pediatric dislocations;
- references:
-
Median nerve palsy after posterolateral elbow dislocation.
- bony displacement:
- when nl elbow is extended, olecranon process & medial & lat form 3
points on straight line, & when nl
elbow is flexed to 90
deg in lateral view, olecranon is aligned vertically w/ epicondyles;
- tip of the olecranon is, however, definitely posterior to the plane
of the epicondyles;
- in post dislocation, olecranon process is displaced backward from its
normal position in relation to
humerus, & one can
palpate the concavity of the semilunar notch;
- increasing degree of elbow flexion exaggerates the prominence of the
olecranon process
- very important to examine whole upper extremity for evaluation of
essex-lopresti lesion at wrist or
associated fractures
-
Radiographs:
- it is essential to obtain radiographs both before and after reduction in
order to asses for associated
fractures (indicating a
complex
dislocations);
- note the radial head avulsion frx, seen in this example;
-
Reduction of the Posterior Dislocation:
- Post Reduction Radiographs and Assessment of Stability:
- generally the elbow will be stable in 90 deg or more of flexion;
- the question is whether the elbow will be stable upto 30 deg flexion;
- if instability occurs in 30 deg of flexion, then place forearm in maximum
pronation which maximizes the
stress on the MCL which reduces the posterolateral subluxation;
- if there is increased stability in pronation, then the elbow should
be placed in a cast brace with the elbow
in
pronation;
- after clinically determining that the reduction will not be lost in 30 deg
of flexion, obtain a portable lateral and
AP radiograph;
- look for joint widening, joint irregularity, or malalignment;
- in difficult cases, flouroscopy can be used;
- in cases of simple dislocation, persistent instability as the elbow is
extended may indicate interposition of soft
tissue or an osteochondral fragment;
- Non Operative Treatment:
- stable articulation will allow for early flexion & extension if valgus
stress is prevented after reduction;
- no one has demonstrated a benefit from operative repair of
MCL in simple dislocations;
- best Rx results are obtained w/ early protected ROM begun before 2 wks;
- if there is increased stability in pronation, then the elbow
should be placed in a cast brace with the elbow
in
pronation;
- final clinical outcome for simple dislocations of the elbow is
dramatically affected by the duration of immobilization;
- recurrent dislocation is unusual;
- mild loss of extension is common, prolonged immobilization over
two wks is assoc w/ greater
flexion
contracture;
- references:
Simple elbow dislocation among adults: A comparative study of two different
methods of treatment.
- Operative Treatment of Simple Dislocations:
- redislocation of elbow w/ passive range of motion or redislocation in
plaster implies severe valgus instability
w/ rupture of both
MCL & flexor forearm muscles;
- under these circumstances, operative treatment is indicated;
- repair of
MCL may be attempted but is not guaranteed to restore stability;
- consider use of a hinged elbow fixator, which will allow early
range of motion as well as stability;
-
arthroscopy: when exam findings unconvincing, possibility of intra-articular
lesion, and reveals radiohumeral
joint laxity
-
Management of Complex Elbow Dislocations:
-
dislocation w/ radial head frx:
- Complications:
- valgus instability:
- patients will show a variable amount of
MCL laxity which correlates with a worse clinical and
radiographic result;
- to maximize the stress on the medial collateral ligament, the
forearm should be placed in full pronation,
which
reduces the posterolateral subluxation;
-
posterolateral instability;
-
heterotopic ossfication
- whether or not all patients with simple elbow frx dislocations
should receive prophylaxis is a matter of controversy;
- chronic dislocations:
- in some cases, recurrent instability will be due to
posterolateral instability;
- management of untreated posterior dislocations of the elbow three
or more wks after injury may require
open
reduction;
-
posterior approach: w/ lengthening of triceps, removal of fibrous tissue, &
possible K-wire stabilization
has been
recommended.
- in the report by H. Moritomo et al. 1998, the authors discuss
reconstruction of the coronoid process
(w/ graft
taken from the olecranon) inorder to help block dislocation;
- Reconstruction of the coronoid process for chronic
dislocation of the elbow. Use of a graft from
the olecranon in two cases. H. Moritomo et al. JBJS. Vol 80-B. No 3. May 1998.
p 490.