Separate vertical wiring plus bilateral anchor girdle suturing fixation reliable method for fractures of inferior pole of patella

Tension band techniques are the most common and reliable methods for the fixation of displaced patellar fractures. However, inferior pole fractures of the patella (IPFPs) are often difficult to fix by tension band wiring due to their small bone fragments and comminution, especially in older pat. Many surgical techniques have been proposed for the restoration of the extensor mechanism in IPFPs, including circumferential wiring, a basket plate, a suture anchor with Krackow-Bunnell weave, and separate vertical wiring. However, all of these techniques have their own limitations.

Li et al introduced a new fixation method for IPFP fixation, that is, separate vertical wiring plus bilateral anchor girdle suturing fixation (SVW-BSAG). Three finite element models including the anterior tension band wiring (ATBW) model, separate vertical wiring (SVW) model and SVW-BSAG model, were built to evaluate the fixation strength of different fixation methods.

A total of 41 consecutive patients with IPFP injury were enrolled in this retrospective study, including 23 patients in the Anterior Tension Band Wiring (ATBW) group and 18 patients in the SVW-BSAG group. The operation time, radiation exposure, full weight-bearing time, Bostman score, extension lag versus contralateral healthy leg, Insall–Salvati ratio, and radiograph outcomes were employed to assess and compare the ATBW group and SVW-BSAG group.

In the SVW-BSAG group, a single guide pin was inserted into the patella along the long axis of the patella and perpendicularly across the fracture. The position of the guide pin was adjusted according to the anteroposterior and lateral C-arm radiographs until the position of the pin was satisfactory. After a cannulated screw was inserted along the guide pin, a cable was separated by vertical wiring through the cannulated screw. Two suture anchors were placed into both sides of the proximal fragment. The entry portal of the anchor was at least 1 cm proximal to the transverse fracture line on the coronal plane and approximately 5 mm posterior to the anterior cortical surface on the cross section. Then, the anchor suture string was sutured along the inferior border of distal fragments on the patellar tendons and knotted with one of the contralateral anchor lines at the entry portal of the contralateral anchor. The same procedure was repeated for the remaining three anchor lines.

The finite element analysis confirmed that the SVW-BSAG fixation method was as reliable as the ATBW fixation method in terms of fixed strength. Through retrospective analysis, the authors found that there was no significant difference between the SVW-BSAG and ATBW groups in age, sex, BMI, fracture side, fracture type, or follow-up time.

There were no significant differences between the two groups in the Insall–Salvati ratio, 6-month Bostman score, and fixation failure.

Compared with the ATBW group, the SVW-BSAG group showed advantages in intraoperative radiation exposure, full weight-bearing time, and extension lag versus the contralateral healthy leg.

“In conclusion, the SVW-BSAG technique exhibited good biomechanical results in simple inferior pole patella fracture model, as well as satisfying functional outcomes and less radiation exposure in clinical practice. We believe that the SVW-BSAG technique can provide stable fixation and allow early functional exercise, making it a simple and effective fixation procedure for IPFP patients and surgeons” the authors commented.

Further reading:

Separate vertical wiring plus bilateral anchor girdle suturing fixation for the fractures of the inferior pole of the patella

Shi Jie Li, Shashi Ranjan Tiwari et al

Journal of Orthopaedic Surgery and Research (2023) 18:176

https://doi.org/10.1186/s13018-023-03649-0