Dynamic Intradigital External Fixation for Proximal Interphalangeal Joint Fracture Dislocations

The authors present modifications to a previously described skeletal traction device used to treat fracture dislocations of the proximal interphalangeal (PIP) joint. Their design improves the stability of the fixation and provides satisfactory functional results. Their report is based on a sample of six patients with fracture dislocations of the PIP joint. Fracture dislocations of the PIP are common injuries. Without proper treatment, pain, stiffness, and posttraumatic arthritis occur. Dorsal dislocations are more common than volar dislocations, and are often seen in ball-handling athletes. Treatment for these fracture dislocations is either nonsurgical or surgical, depending on the severity of the comminution and the stability of the PIP joint. Surgical treatment is required when the fracture is unstable, and/or when there is significant fragment displacement. There are many surgical treatment techniques described: closed reduction and percutaneous pinning, dorsal extension block pinning, open reduction and internal fixation, and traction fixation. Early mobilization of the PIP along with traction and stable fixation offer the most favorable functional outcomes. Gaul and Rosenberg devised a simple frame that provided traction without rubber bands or complicated connecting pieces. The authors introduce their own modification to the frame created by Gaul and Rosenberg and describe its use in six patients with fracture dislocation of the PIP.

Methods: The authors treated six patients (four male, two female) who sustained a fracture dislocation of the PIP with a dynamic external fixator. Fracture dislocation was caused by crush injury on all patients and the fractures were all closed. Average age of the patient was 27 years (range 21–42 years). The middle finger was involved in three patients, the little finger in two patients, and the ring finger in one patient. Average follow-up period was 24 months (7–43 months).

Surgical Technique: Digital block anesthesia is administered and 1.4-mm K wire (K1) placed transversely through the center of the head of the proximal phalanx under fluoroscopy. Another K wire (K2) is driven through the head of the middle phalanx. The K1 wire actually protrudes out on each side of the PIP joint and is bent at a 90° angle there so that the ends lay parallel and 1 cm away from the middle phalanx. The original description by Gaul and Rosenberg outlined a volar direction and longer lever arm of this K1 wire. The modifications by the author ensure a traction force parallel to the middle phalanx that will not lead to a loss of distraction force over time. The K1 wire is bent to 90° again at the level of the base of the distal phalanx where it loops into and hooks around the K2 wire. This is how the traction force is applied and maintained. The amount of distraction of the joint space is then evaluated and confirmed by x-ray. Open reduction is only necessary when articular fragments remain displaced. Fluroscopy is used to monitor flexion and extension of the PIP with the external fixator in place. Soft, minimally bulky dressings are applied for the first postoperative day. But immediate active PIP motion, supervised by a hand therapist is initiated on the following day. The fixator provides traction and maintains joint space while allowing for active motion. It remains in place for 3–4 weeks.

Results: The average range of motion (ROM) of the PIP at the follow-up evaluation was 5–89° (range 0–100°). The average ROM of the Distal Interphalangeal joint (DIP) was 2–80° (0–90°). At final evaluation, no instability of the PIP was noted.

Case Report: The authors include the case report of a 21-year-old male who sustained an intra-articular fracture dislocation of the PIP of the right little finger. The external fixator described here was placed on his involved finger. Hand therapy was initiated and active motion exercises were introduced immediately. The fixator was removed after three weeks, and therapy continued until full motion was achieved. The patient demonstrated 5–90° ROM at the PIP and 0–75° of motion at the DIP at follow-up evaluation.

Discussion: The authors maintain that early mobilization of the PIP after fracture/dislocation is critical to avoid stiffness and permanent ankylosis. The literature describes many techniques for this including Inanami's dynamic external fixator and the compass hinge as reported by Bain et al. and others. However, many complications (infection and breakage) have been reported with these devices. Other methods incorporate rubber bands for traction that the authors maintain are susceptible to plastic deformation and cause deforming forces. The authors recommend their procedure as the best method for treatment of fracture dislocation of the PIP because it is easy to apply, inexpensive, and time efficient procedure, without major complications for the patient.

Reviewer's Commentary: As hand therapists treating difficult PIP injuries, we understand the benefits of early mobilization. The external device described maintains the PIP space and allows for early flexion and extension motion. It is held in place for a relatively short time, only three to four weeks. This is important information because the external pin protrusion makes full fist making and tendon gliding exercises difficult. No description of pin site care is offered (two patients developed pin tract infection treated with oral antibiotics). Information regarding protective splinting and positioning for in-between exercise sessions and at night is lacking. Despite the satisfactory functional outcomes reported, the small sample size of six patients is also a limitation of this study.