What is thumb dislocation ?
The term dislocation refers to complete or partial rupture of
Ligaments are fibrous structures that keep joints stable and allow
their use without undergoing deformations. In case of a serious
dislocation (complete rupture of a ligament), the joint becomes
unstable, and the function of the thumb is definitely altered.
The joint of the thumb, between the metacarpal and the first phalanx,
has two major ligaments (ulnar collateral ligament and dorsal
collateral ligament) which may suffer from trauma and even rupture.
Affection of the ulnar collateral ligament (towards the second
finger) is the most common one, and will be described below.
When rupture of the ulnar collateral ligament occurs, the pinch
and grip function between the index and the thumb is becomes difficult
and unstable. This is due to the loss of stabilisation of the
metacrapophalangeal thumb joint.
Complete ruptures of the internal lateral ligament should be surgically
Which are the clinical signs ?
collateral ligament dislocations result from trauma which abruptly
tears the thumb open. It is most frequently caused by falls while
skiing. A fall on the snow -with or without the poles- causes
dislocation. Pain and slight swelling occur in the thumb. The
examination performed by a doctor seeks collateral instability
of the thumb joint. The doctor grabs the first phalanx of the
thumb and performs vulgus motions (the second finger is opened).
In the case of serious dislocation, the thumb may be opened abnormally
with some pain.
This tests confirms ligamentous rupture; therefore, surgery is
required. Owing to the pain and swelling, this test is sometimes
difficult to be applied; it is the doctor's expertise that will
help interpret this examination. After a few days with immobilisation,
a second examination may be needed to confirm diagnosis.
Which complementary examinations are
An AP radiograph is made, no significant fracture is observed,
but sometimes there may be some minimum bone rupture at the base
of the thumb which confirms the dislocation.
Radioscopy confirms lateral laxity.
How is it treated ?
1 - Non surgical treatment.
Not all dislocations need to be surgically treated. In fact, rupture
of a ligament may partial, which does not destabilise the joint.
In such case, orthopaedic treatment is indicated: immobilisation
with a fixed plaster cast or resin to block the metacarpophalangeal
joint of the thumb, with the wrist released. This immobilisation
should be kept for three weeks. After removal of the immobilisation,
the patient will gradually regain thumb motion, and should take
care for two months. Provided motion is not spontaneously regained,
a few rehabilitation sessions will be needed.
2 - Surgical treatment.
Serious dislocations (complete rupture of the ulnar collateral
ligament) should be surgically treated. It does not pose an emergency
situation; the patient may be temporarily immobilised . If the
doctor agrees (to end his/her stay or return home) to be operated
on, it is required that the operation is performed within six
days to be successful.
on the inside part of the joint, and reinsertion of the torn ligament
: this reinsertion is possible as long as it is recent
of the thumb in the postoperative period for 3-6 weeks, according
to the surgeon's procedures.
sessions are usually required to regain fill motion of the thumb.
advised not to practise any sports or male any efforts with the
thumb for 4 months.
Which are the risks during the development
of the injury ?
Presence of the injury is ignored :
This is likely to happen due to reasons we will not death with.
The patient presents difficulty using the thumb, which he/she is
used to (sometimes for years). Pains are rare. When pinch and grip
function is attempted, the patient cannot actually grab at the moment
of grip motion.
Surgical intervention may be indicated -if it is the patient's will-
to stabilise the thumb.
Two possibilities :
of the ligament will be proposed provided the radiograph indicated
that the joint is not altered. The result of this procedure is generally
are indicative of an altered joint (sings of arthrosis) ; a joint
block is indicated (arthrodesis) This block is definitive and the
function of the hand will be perfect despite the block.
Failure of the initial treatment due to :
choice of initial therapy : immobilisation of an injury that actually
required surgical treatment.
Failure to reinsert a ligament,
protocol described above will be proposed.
Complications may arise after any of the treatments ; thumb stiffness,
algodystrophy, etc. This will require a specific treatment.