Efficacy comparison of Kirschner-wire tension band combined with patellar cerclage and anchor-loop plate in treatment of inferior patellar pole fracture

Abstract

Objective: This study aimed to compare the biomechanical stability and clinical efficacy of the Kirschner-wire (K-wire) tension band combined with patellar cerclage and an anchor-loop plate (ALP) in treating inferior-pole patellar fracture. Methods: The finite element model was established to analyze the mechanical properties of a K-wire tension band combined with patellar cerclage and ALP fixation in the treatment of inferior patellar pole fracture. The clinical data of 49 patients with patellar inferior-pole fracture (AO/OTA 34 A1) admitted to our hospital from January 2017 to July 2021 were retrospectively analyzed. Among these, 28 cases were fixed with ALPs (ALP group) and 21 cases were fixed with K-wire tension bands combined with patellar cerclage (K-wire group). By reviewing the medical records and follow-up results, we compared the operation time, final knee joint activity, incidence of secondary surgery, postoperative complications, and joint function recovery between the two groups. Results: The biomechanical analysis of the finite element model showed that the maximum displacement of the K-wire group was 1.87 times that of the ALP group. The maximum stress of the K-wire group was 1.34 times that of the ALP group. The maximum stress of the pole bone in the K-wire group was 13.89 times that of the ALP group. The average follow-up times of the K-wire group and ALP group were similar (p > 0.05), and the average ages of the two groups were similar (p > 0.05). The operation time of the ALP group was significantly shorter than that of the K-wire group (p < 0.05).The final knee joint activity of the ALP group was significantly greater than that of the K-wire group (p < 0.05). The Bostman patellar fracture function score of the ALP group was significantly better than that of the K-wire group at 3 and 9 months after operation (p < 0.05). Postoperative complications of the two groups included 1 case (3.6%) in the ALP group with internal fixation-stimulation complications and, in the K-wire group, 3 cases (14.3%) with internal fixation stimulation complications and 1 case (4.8%) with infection. Conclusion: The ALP and K-wire tension band combined with patella cerclage models were tested at 500 N, and no damage occurred, indicating that the newly designed ALP is safe in mechanical structure. The ALP has better therapeutic effect in biomechanical stability, postoperative complications, secondary surgery, and knee function. This technique is an effective method for the treatment of inferior-pole patellar fracture.

Keywords: finite element analysis; inferior pole; patellar fractures; plates; tension band.

FIGURE 1

Model after meshing.

FIGURE 2

Microplate formed by bending.

FIGURE 3

Intraoperative situation of ALP in the treatment of inferior pole patellar fracture. (A) Incision of a small opening at the junction of the patellar ligament and inferior pole with a scalpel. (B) One end of the long arm of the pre-flexed plate passes through the small opening of the patellar ligament. (C) Plasticized bone plate penetrated steel wire. (D) Ring wire assisted by lumbar puncture after fracture reduction. (E) Intraoperative fluoroscopy. (F) Immediate joint passive flexion and extension activity.

FIGURE 4

Model displacement distribution program of K-wire group (A) and ALP group (B). K-wire group (C) and ALP group (D) model internal fixation stress distribution program. Stress distribution program of the polar bone block under K-wire group (E) and ALP group (F) models.

FIGURE 5

A 56-year-old male presented with a fracture of the inferior pole of the left patella caused by a fall injury. Preoperative CT (A,B), postoperative knee X-ray (C,D). X-ray films and knee joint function 12 months after operation (E–H).

FIGURE 6

A 45-year-old man suffered a fracture of the inferior pole of the right patella due to a fall. Preoperative X-ray (A), postoperative knee joint X-ray (B,C). The X-ray film (D) was reexamined 9 months after operation.

FIGURE 7

A 66-year-old female patient underwent tension band fixation for two months after the review results (A), and a 29-year-old male patient underwent tension band fixation for one month after the review results (B,C). The above female patient chose partial patellar resection and patellar ligament reconstruction surgery, and the above male patient chose to use the ALP for secondary fixation. Two days after the review results (D,E) and three months after the review results (F). At 9 months after operation, the knee joint function had recovered well (G,H).