Research Information System
JOURNAL OF ORTHOPAEDIC SURGERY AND RESEARCH, vol.20, no.148, pp.1-10, 2025 (SCI-Expanded)
Abstract
Background The selection of an implant is a critical factor in the surgical treatment of patella fractures due to the risk
of various complications, such as non-union, implant failure, and irritation. The present study evaluated and compared
the biomechanical strength of headless cannulated screws about screw length using the tension band wiring
technique.
Methods Forty-eight sawbone patellas with transverse fractures were divided into three fixation groups based
on the screw length used in tension band wiring. Overall, three different fixation groups were determined: Group
1 (recessed headless cannulated screw fixation), Group 2 (full-length headless cannulated screw fixation), and
Group 3 (protruding headless cannulated screw fixation). A setup was used to simulate a knee with a flexion angle
of 60 degrees. Specimens underwent biomechanical testing under axial traction (static test) and cyclic loading
(dynamic test). Displacements at 300 Newtons (N), loads at 2 millimetres (mm) displacement, and failure loads were
documented for each sample in the static test. In the dynamic test protocol, 10,000 repetitive cycles were performed
under physiological load between 100 and 300 N, and final displacements were recorded.
Results There were significant differences in the loads achieved at 2 mm displacement levels, and Group 3
demonstrated lower force values compared to other constructs in the static test (P = 0.003). All groups revealed similar
displacements at 300 N and failure load values under axial traction. In the dynamic test, Group 3 had significantly
higher fracture displacement under cyclic loading compared to the other specimens (P = 0.006).
Conclusions This study found headless cannulated screws for transverse patella fracture fixation provide sufficient
stability; however, protruding headless screws reduce the fixation strength. Recessed or full-length screws may
improve stability and bony healing, potentially preventing complications in patella fractures.
Level of evidence Biomechanical study N/A.
Keywords Patella fracture, Tension band wiring, Headless cannulated screw, Biomechanic