Treatment of Mallet Fractures with a Transverse Two-Hole Mini Plate
Mallet fractures are a common type of hand injury, often resulting from trauma to the distal interphalangeal joint (DIPJ). While non-surgical treatment may be suitable for small fracture fragments without DIPJ subluxation, surgical intervention is frequently recommended to restore the joint surface accurately. Accurate reduction is crucial to prevent complications such as secondary osteoarthritis, loss of movement, and poor cosmetic outcomes. Various surgical techniques, including extension block pinning, hook plate fixation, and umbrella handle-like K-wire fixation, have been developed to address mallet fractures. However, achieving stable fixation can be challenging, particularly when the fracture fragment is small or comminuted. To address these challenges, a novel approach using a transverse two-hole mini plate was developed and evaluated in a clinical study.
The study involved 155 patients (157 fingers) with mallet fractures who underwent open reduction and internal fixation using a transverse two-hole mini plate. The surgical procedure began with a transverse curved incision to explore the extensor tendon. The fracture line was identified, and any soft tissue or hematoma between the fracture ends was debrided. The fracture fragment was then reduced and stabilized using a two-hole 1.7-mm mini plate from the Stryker mini plate system, secured with two screws. To maintain extension and reduction, a 0.9-mm K-wire was inserted across the DIPJ. The reduction and stability of the fracture fragment were assessed using a mini C-arm image intensifier. The K-wire was typically removed 2 to 6 weeks post-surgery, depending on the stability of the fixation and the progress of bone healing. Smaller bone fragments generally required a longer duration of K-wire fixation.
Postoperative follow-up included regular assessments of the active range of motion (ROM) using a goniometer, radiographic imaging at 4, 6, and 8 weeks, and then every 3 months until the end of follow-up. Pain was evaluated using a visual analog scale (VAS). The study population consisted of 122 men and 33 women, with a mean age of 33.2 years (range: 16–62 years). The right hand was injured in 90 patients, and the left hand in 65 patients. The little finger was the most commonly injured digit (66 cases), followed by the ring finger (48 cases), long finger (30 cases), index finger (11 cases), and thumb (2 cases).
The average articular surface of the fracture fragment was 39% (range: 12%–67%) of the joint surface. DIPJ subluxation was observed in 31 injured fingers. The mean follow-up period was 5.0 months. All patients achieved bone union, with radiographic evidence of union within 6 weeks of surgery. The average final active range of flexion of the DIPJ was 65° (range: 55°–75°), and the extensor lag was 0° (range: 0°–5°). Significant pain relief was reported in all cases. Based on the Crawford criteria, 47 fingers achieved excellent results, 95 achieved good results, and 15 achieved fair results. Extensor tendon rupture was observed in 8 fingers, all of which were acute cases, resulting in an extensor rupture rate of 6.3% in acute cases and 5.1% overall. Complications included superficial infection in 1 case, postoperative skin irritation from the plate and screws in 5 cases, and joint step-off without clinical discomfort in 8 cases. No instances of skin necrosis or nail deformity were reported. The superficial infection was successfully treated with oral antibiotics and wound care, while hardware irritation necessitated plate and screw removal in affected cases.
Statistical analysis revealed no significant differences in ROM between acute and chronic cases, or between male and female patients. Similarly, no significant differences were observed in ROM or extension lag among different fingers, sides of injury, or time from injury to surgery. However, a negative correlation was found between age and ROM, with a coefficient of -0.293. No significant correlation was observed between age and extension lag. Preoperative and postoperative VAS scores showed a significant difference, with a median preoperative score of 4.0 (range: 3.6–4.6) and a median postoperative score of 0.0 (range: 0.0–0.1).
The study highlighted that mallet fractures often occur without extensor tendon rupture, distinguishing them from mallet fingers with extensor laceration. The force applied to the joint in extension can lead to a bony dorsal edge fracture with articular involvement, while hyperflexion trauma typically results in plastic deformation or rupture of the extensor tendon, with or without a tiny dorsal bony avulsion. The transverse two-hole mini plate fixation method was found to be effective for various sizes of fracture fragments, as the plate acts as a washer to press the fragment into a reduced position, making screw insertion easier. However, this method is not suitable for comminuted fractures involving both volar and dorsal sides, or for avulsion fractures with very tiny fragments that cannot be stably pressed by the plate. Additionally, the method is contraindicated in cases of infection or potential infection and is more expensive compared to extension block pinning, making it more appropriate for cases where extension block pinning is not feasible.
In conclusion, the transverse two-hole mini plate fixation method offers a reliable and effective approach for treating mallet fractures, particularly in cases where stable fixation is challenging. The technique provides accurate reduction, stable fixation, and favorable functional outcomes, with a low rate of complications. However, careful patient selection is essential to ensure the suitability of this method for specific fracture types and clinical scenarios. Further research and long-term follow-up studies are warranted to validate these findings and optimize the treatment of mallet fractures.
doi.org/10.1097/CM9.0000000000000501
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