Design and Evaluation of Kirschner Wire Guide Device for Patellar Fracture Fixation

Identifying the optimal position for Kirschner wire (K-wire) is crucial in tension band wiring for patellar fracture. This study analyzed the ideal position and designed a guide device to aid precise K-wire insertion. The stress and displacement at 90 deg of flexion were compared to determine the optimal positions. The number of insertions and fluoroscopies, and operating times were recorded in a retrospective study. Intra-operative radiographs were used to measure the K-wire position relative to the patella in the coronal and sagittal planes to assess accuracy. The least stability occurred when the distance between the K-wires was 1/2 of the patellar width in the coronal plane and close to the patellar anterior surface. The number of K-wire insertions in the experimental group and control group (1.33 ± 0.58 versus 3.8 ± 1.03; P = 0.009), the number of fluoroscopies (2.67 ± 0.58 versus 10 ± 1.33; P = 0.007), and the operating time (55 ± 8.66 min versus 82 ± 9.49 min; P = 0.001) were significantly different. K-wires should parallel to each other, spaced 1/4 or 1/3 of the patellar width in the coronal plane, and 1/2 to 3/4 of the patellar thickness in the sagittal plane away from the patellar anterior surface. The surgeon could improve insertion accuracy with guide device.