Keywords
dislocation - volar - metacarpophalangeal - thumb - ulnar collateral ligament - WALANT
Introduction
A set of fundamental elements forms the metacarpophalangeal (MCP) joint of the thumb
and allows its complete functioning: the volar plate, the capsule, and the collateral
ligaments. MCP joint dislocations are rare, and most cases are dorsal dislocations.
A search in the literature in English retrieved less than 30 studies, the first one
dating from 1974.[1]
[2]
In a volar dislocation, the joint injury usually results from the hyperflexion of
the thumb or a force on the flexed phalanx.[2] Most volar dislocations require an open reduction due to the interposition of different
elements in the MCP joint. Sometimes, the ulnar collateral ligament is damaged and
needs review despite the successful closed reduction. The literature reports cases
requiring ulnar collateral ligament (UCL) review 7 days after a closed reduction due
to its subluxation and instability.[2] This condition needs correct treatment and follow-up as it is essential for pincer
grasp and hand grip.[2]
We present the clinical case of a patient who suffered a volar dislocation of the
metacarpophalangeal joint of the thumb in the blocked left hand that required open
reduction in the operating room due to an associated rupture of the UCL and soft tissue
interposition. For surgical review, we used the wide-awake local anesthesia with no
tourniquet (WALANT) technique, an anesthetic technique for upper limb surgeries showing
significant advantages over the usual techniques.
Clinical Case
A 59-year-old female patient suffered a fall from her own height and went to the Emergency
Department 24 hours after trauma due to pain, severe deformity, and functional impotence
in the first finger of her left hand. Examination and plain radiography ([Figure 1]) showed a volar MCP dislocation of the first finger. Upon arrival, an attempt at
a closed reduction with a trunk block was unsuccessful, so we decided on an open reduction
and review in the operating room.
Fig. 1 Radiograph of a metacarpophalangeal volar dislocation of the first finger in the
emergency room.
Under strict aseptic measures, we anesthetized the first finger of the left hand with
the WALANT technique, thus avoiding the use of an ischemia cuff. WALANT is a local
anesthesia technique with epinephrine. A mixture of lidocaine 1% and 0.0005 mg/mL
epinephrine is diluted in 1 mL of 0.5 mmol/mL sodium bicarbonate for every 9 mL of
lidocaine.[3]
[4] Of the total diluted solution of 10.1 mL, we injected 0.5 mL under the dermis, 2 mL
in the volar and dorsal zone of the proximal phalanx, and the remaining volume around
the head of the first metacarpal bone.[5] We performed a dorsoulnar approach on the first finger of the left hand at the MCP
joint level. We observed a rupture of the dorsal capsule, ulnar dislocation of the
extensor pollicis longus (EPL) and extensor pollicis brevis (EPB) tendons, and disinsertion
of the UCL at the level of the base of the proximal phalanx of the first finger. First,
we performed an open reduction of the joint, achieving self-reduction of the extensor
tendons; next, we repaired the UCL with a 2.4 mm harpoon at the proximal phalanx level.
After the ligamentous and capsular repair, we asked the patient to move the thumb,
flexing and extending the MCP. Since we noted persistent joint instability, we decided
to add a percutaneous Kirschner wire to immobilize the joint ([Figure 2]). The patient underwent immobilization with a spica cast for 4 weeks after surgery.
Subsequently, we removed the immobilization and the Kirschner needle at the 1-month
follow-up visit and placed an orthosis for 2 more weeks as protection.
Fig. 2 Radiograph after urgent surgery.
Follow-up visits occurred at 1 month, 3 months, 6 months, and 1 year after surgery.
She started with passive and active mobilization exercises with no resistance at 4
weeks at home, progressing to counterresistance exercises at 3 months. Since mobility
evolved progressively and satisfactorily from the beginning, the patient did not require
additional rehabilitation treatment. An exploration at 6 months showed MCP joint flexion
of 60° and extension of 0°. The modified Kapandji index was 8 points. The patient
had no pain, and the end-to-end pinch force was slightly lower than in the contralateral
hand, at 5 kg (the pincer grasp strength in the right hand was 6 kg). The joint was
congruent and stable both clinically and radiologically ([Figure 3]). After 1 year, the patient remains asymptomatic, and we discharged her from follow-up
visits.
Fig. 3 Radiograph 3 months after surgery.
Discussion
Senda and Okamoto classify the volar MCP dislocation into three categories: stable,
unstable, and locked.[1]
[2] Stable dislocations are successfully reduced in a closed approach and often present
partial UCL injury, with no need for surgical treatment. Unstable dislocations allow
a closed reduction but present complete UCL damage resulting in total joint instability;
the lack of an open repair within 3 weeks leads to chronic instability, pain, and
loss of strength. In a volar dislocation, it is essential to check joint stability
after its reduction to avoid these issues. Lastly, blocked dislocations, such as the
one observed in our patient, cannot be reduced in a closed approach because there
is generally an interposition of the EPL and/or EPB tendons in the joint and a complete
UCL lesion requiring an open reduction and surgical repair.
In addition to the classification establishing the need or not for open reduction,
some indirect signs guide us towards surgical treatment, such as radiological interposition
of the sesamoid bones, EPB and/or EPL deviation, the impossibility of EPL palpation,[6] and the paradoxical mobility of the MCP joint (MCP flexion with interphalangeal
extension with the MCP joint in extension). In our patient, given the joint instability,
especially in the valgus, the absence of extensor tendons on palpation at the dorsal
level, and the impossibility of a closed reduction led us to perform an open reduction
and lesion exploration in the operating room, ensuring UCL repair and its consequent
contribution to joint stability.
Lastly, we highlight the use of the WALANT technique, characterized by the use of
epinephrine with a local anesthetic agent, thus avoiding surgical bed bleeding and
the need for an ischemia cuff, the main cause of pain during surgery. This reduces
the pre-surgical stress of the patient, favors their collaboration during the intervention,
and reduces the use of postoperative analgesic agents and the hospital stay.[7]
In addition, different studies concluded that using the WALANT technique in hand surgery
results in the same outcomes, does not increase complications, and reduces surgical
time, the material and personnel required for the procedure, and side effects from
general anesthesia.[3]
[4]
[8]
Therefore, we must not forget WALANT as an anesthetic technique in selected hand surgeries
since it has significant advantages over general anesthesia without affecting patient
comfort.
