A pilot hole does not reduce the strains or risk of fracture to the lateral cortex during and following a medial opening wedge high tibial osteotomy in cadaveric specimens

Abstract

Aim: It has been suggested that the use of a pilot-hole may reduce the risk of fracture to the lateral cortex. Therefore the purpose of this study was to determine the effect of a pilot hole on the strains and occurrence of fractures at the lateral cortex during the opening of a high tibial osteotomy (HTO) and post-surgery loading.

Materials and methods: A total of 14 cadaveric tibias were randomized to either a pilot hole (n = 7) or a no-hole (n = 7) condition. Lateral cortex strains were measured while the osteotomy was opened 9 mm and secured in place with a locking plate. The tibias were then subjected to an initial 800 N load that increased by 200 N every 5000 cycles, until failure or a maximum load of 2500 N.

Results: There was no significant difference in the strains on the lateral cortex during HTO opening between the pilot hole and no-hole conditions. Similarly, the lateral cortex and fixation plate strains were not significantly different during cyclic loading between the two conditions. Using a pilot hole did not significantly decrease the strains experienced at the lateral cortex, nor did it reduce the risk of fracture.

Conclusions: The nonsignificant differences found here most likely occurred because the pilot hole merely translated the stress concentration laterally to a parallel point on the surface of the hole.Cite this article: K. Bujnowski, A. Getgood, K. Leitch, J. Farr, C. Dunning, T. A. Burkhart. A pilot hole does not reduce the strains or risk of fracture to the lateral cortex during and following a medial opening wedge high tibial osteotomy in cadaveric specimens. Bone Joint Res 2018;7:166-172. DOI: 10.1302/2046-3758.72.BJR-2017-0337.R1.

Keywords: Fixation Plate; Fracture; High Tibial Osteotomy; Lateral Cortical Strains; Lateral cortex; Tibial osteotomy.

Fluoroscopic images of a) the resulting osteotomy cut and b) the pilot hole.

Fig. 2

The tibia potted at 15° with respect to a composite femur (not shown) and with the osteotomy fixation plate shown on the medial aspect (inset). It should be noted that the white insert was only used to establish the width of the opening and was not left in for testing.

Fig. 3

The experimental setup, including the multi-axis fixation jig within the materials testing machine.

Examples of the common fracture patterns resulting from the opening of the osteotomy; a) no-hole condition and b) pilot hole condition. Both figures show the propagation of a crack from a) the apex of the cut and b) the edge of the hole laterally through the tibiofibular joint surface towards the cortical hinge.

Fig. 5

Comparison of the Mean (sd) lateral cortex strains during the opening of the high tibial osteotomy between the pilot hole (n = 7) and no-hole condition (n = 7).

Typical fracture patterns after cyclic loading. a) Propagation of the crack through to the lateral cortex and b) shearing of the lateral cortex.

Comparison of the mean (SD) strains corresponding to the 800N cyclic loading protocol between the pilot hole (n = 3) and no-hole conditions (n = 3). Strains were measured at a) the lateral cortex and b) the fixation plate and there were no significant differences between conditions at either the lateral cortex or the fixation plate.