Background: Displaced patellar fractures are commonly stabilized with a modified anterior tension-band construct. The goal of the current study was to compare the incidence of complications after tension-band fixation of the patella with Kirschner wires as compared with cannulated screws.
Methods: We performed a retrospective cohort study of consecutive, surgically treated patellar fractures. Patients were divided into two cohorts: fractures fixed with use of Kirschner wires and fractures fixed with use of cannulated screws. The primary outcome measure was early loss of fixation that necessitated revision surgery. Secondary outcomes included early postoperative infection and the need for implant removal.
Results: Four hundred and forty-eight patellar fractures were studied. Kirschner wires were used for fixation in 315 (70%), and cannulated screws were used for fixation in 133 (30%). The incidence of fixation failure was 3.5% in the Kirschner-wire group and 7.5% in the screw group (p = 0.065). A postoperative infection occurred in 4.4% of patients in the Kirschner-wire group and 1.5% of patients in the screw group (p = 0.17). One hundred sixteen (37%) patients in the Kirschner-wire group and 30 (23%) in the screw group underwent elective implant removal (p = 0.003). After adjusting for confounding variables, a trend toward increased incidence of fixation failure with screws as compared with Kirschner wires was present (p = 0.083). Patients treated with Kirschner wires were twice as likely to undergo implant removal compared with those treated with screws (p = 0.002).
Conclusions: Serious complications are uncommon following treatment of patellar fractures with a modified tension-band technique, with use of either Kirschner wires or cannulated screws. In both groups the rate of fixation failure was low, as was the rate of postoperative infection. Symptomatic implants, the most common complication observed, were twice as frequent in patients treated with Kirschner wires.
Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
1Department of Orthopaedic Surgery, Harbor-UCLA Medical Center, 1000 West Carson Street, Box 422, Torrance, CA 90509
2Department of Research and Evaluation, Kaiser Permanente Southern California, 100 South Los Robles Avenue, Pasadena, CA 91101
3Department of Orthopaedic Surgery, Kaiser Permanente South Bay Medical Center, 25821 South Vermont Avenue, Harbor City, CA 90710. E-mail address: Ronald.A.Navarro@kp.org