Treatment of an intraarticular comminuted fracture of the base of the proximal phalanx in a ring finger using the Ichi-Fixator external fixator system: A case report

Highlights • Intra-articular comminuted fracture of MP joint was relatively rare.• MP joint of ring finger was injured.• Eventually range of motion of affected finger was fully recovered.• Ichi-Fixator System was useful for comminuted intraarticular fracture of MP joint.


Introduction
Fractures of the lateral volar base of the proximal phalanx are common injuries and usually represent with collateral ligament avulsion injuries. In contrast, comminuted fractures involving the articular surface of the base of the proximal phalanx are relatively rare and usually represent as a volar base fracture with a central depression of the articular surface. Failure to reduce and secure the fracture leads to persistent subluxation, articular incongruity, and post-traumatic arthritis. These fractures are generally approached through a dorsal extensor-tendon-splitting incision [1] or volar A1 pulley approach to visualize the articular surface [2]. Most commonly, a significantly-sized palmar-ulnar or palmar-radial fragment exists, and fixation can be accomplished with a minicondylar plate or K-wires. We experienced a patient with a comminuted intraarticular fracture of the base of the proximal phalanx, which we treated by open reduction and internal fixation with a locked-wire-type external fixator (Ichi-Fixator System (IFS); Neo-medical, Saitama, Japan) [3,4]. The work has been reported in line with the SCARE criteria [5].

Case report
A 45-year-old man presented to our hospital because of a ring finger injury. One day earlier, he played Futsal as a goalkeeper, when another player accidentally kicked the patient's ring finger while the patient was saving the ball. At presentation, his ring finger was swollen without a wound. Plain radiographs showed a comminuted intraarticular fracture of the base of his ring finger proximal phalanx (Fig. 1). Computed tomography revealed a comminuted fracture with articular depression of a fragment of the proximal phalangeal base (Fig. 2). We explained that closed reduction and conservative treatment would be failed. The patient chose operative treatment. Surgery was performed 10 days after his first visit. We approached the fracture site via dorsal extensor-tendon-  splitting. The extensor mechanism was opened longitudinally, the dorsal capsule transversely, and the articular fracture visualized. The depressed central fragment was elevated and restored to the joint surface. We inserted two K-wires subchondrally in the dorsopalmar direction to reduce the joint fragments and sustain the joint surface in situ, which provided anatomical joint restoration. We applied the external fixator (IFS) to the proximal phalanx and metacarpal bone of the patient's ring finger as a distraction fixator to temporarily fix the fracture (Fig. 3). The external fixator and K-wires were removed 5 weeks after the operation, and active and passive range of motion exercises were encouraged. Three months after the operation, plain radiographs showed bone union without joint deformity (Fig. 4). Five months after the operation, the patient's finger motion was fully recovered without restriction (Fig. 5), and he returned to his previous work soon after the operation.

Discussion
Comminuted fractures involving the articular surface of the base of the proximal phalanx are relatively rare and are a challenge for hand surgeons because of the difficulty in achieving accurate reduction of the articular surface and obtaining secure fixation. These fractures usually present as a volar base fracture with a central depression of the articular surface, and are generally approached through a dorsal extensor-tendon-splitting incision to visualize the articular surface [1]. Fixation can be accomplished with a minicondylar plate or K-wires. Otherwise, the volar A1 pulley approach for open reduction and internal fixation with volar plating is used [2]. If the fracture is notably comminuted, skeletal traction or an external fixator should be considered. Although dorsal plating of the proximal phalanx provides rigid internal fixation that facilitates early range of motion exercises, complications and unsatisfactory results have been reported, namely, interference with excursion of the central slip and lateral bands, extensor tendon rupture, and plate prominence [6,7]. When volar plating was used, the potential complications were adhesion or bowstring of the flexor tendons, and plate prominence [2]. In our patient, because the joint surface was comminuted with joint depression, plate fixation was not an option. We chose open reduction of the joint fragments using the dorsal approach and fixation of the joint fragments with K-wires followed by applying the IFS. After anatomical reduction, the IFS provides relatively solid and temporary fixation as a distraction fixator. This apparatus is simple to apply, and has a low profile and minimal impact on the adjacent finger. Because the IFS can be used as a unilateral fixator, it can be used even for long or ring finger metacarpophalangeal joints where other external fixators such as the bilateral type or hinged external fixators are difficult to use.

Sources of funding
We have no source.

Ethical approval
It is retrospective case report and no ethical approval was required.

Consent
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request. Patient's name, initials, or hospital numbers are not used in this manuscript.

Author contribution
Akira Hara and Minoru Yokoyama conducted a literature search and drafted the manuscript.
Akira Hara and Minoru Yokoyama performed the operation. Akira Hara and Satoshi Ichihara contributed during the patient management and participated in the design of the case report and coordination and helped draft the manuscript.
All authors read and approved the final manuscript. Akira Hara wrote up. Yuichiro Maruyama was consultant involved in management of patient, main guidance for write up.

Registration of research studies
No.

Provenance and peer review
Editorially reviewed, not externally peer-reviewed.

Declaration of Competing Interest
None of the authors have conflict of interest.