Evidence Based Development of a Novel Lateral Fibula Plate (VariAx Fibula) Using a Real CT Bone Data Based Optimization Process During Device Development

Abstract

Development of novel implants in orthopaedic trauma surgery is based on limited datasets of cadaver trials or artificial bone models. A method has been developed whereby implants can be constructed in an evidence based method founded on a large anatomic database consisting of more than 2.000 datasets of bones extracted from CT scans. The aim of this study was the development and clinical application of an anatomically pre-contoured plate for the treatment of distal fibular fractures based on the anatomical database.48 Caucasian and Asian bone models (left and right) from the database were used for the preliminary optimization process and validation of the fibula plate. The implant was constructed to fit bilaterally in a lateral position of the fibula. Then a biomechanical comparison of the designed implant to the current gold standard in the treatment of distal fibular fractures (locking 1/3 tubular plate) was conducted. Finally, a clinical surveillance study to evaluate the grade of implant fit achieved was performed. The results showed that with a virtual anatomic database it was possible to design a fibula plate with an optimized fit for a large proportion of the population. Biomechanical testing showed the novel fibula plate to be superior to 1/3 tubular plates in 4-point bending tests. The clinical application showed a very high degree of primary implant fit. Only in a small minority of cases further intra-operative implant bending was necessary. Therefore, the goal to develop an implant for the treatment of distal fibular fractures based on the evidence of a large anatomical database could be attained. Biomechanical testing showed good results regarding the stability and the clinical application confirmed the high grade of anatomical fit.

Fit assessment of two different anatomically contoured distal femur plate sets on cadaveric bones

“…Several definition methods for the fit optimization of a precontoured fracture fixation plate for a given bone data set have been presented in the literature. [13][14][15][16][17][18][19] In most of them, the fitting of the plate to the bone is conducted entirely in a virtual environment utilizing computer graphical methods and three-dimensional bone and plate models based on computer tomography scans. In contrast to these studies in which the computer places the plate in the best position, in our study, the plate was placed over the bone as was implemented in actual surgery.…”

“…The mean distance between the plate surface and the underlying bone surface, [15][16][17] the maximum distance between the plate and the underlying bone surface, [18,19] and also the volume between the plate and underlying bone surface [13] were used as fit assessment parameters. Furthermore, qualitative evaluation was used in some studies.…”

“…In the literature, there are many experimental biomedical engineering studies that used expensive and complex methods to place the plates virtually and calculated the mean or the maximum distance or the volume between the plate surface and underlying bone surface in term of fit assessment. [13][14][15][16][17][18][19] We proposed a novel method which is inexpensive and simple to find the volume between the cadaver bone and the plate placed, using a similar technique in a surgical procedure so as to assess a quantitative fit parameter. [20] This method is used to investigate the plate bone congruence with the two most commonly used plate sets from two different companies in our clinic for distal femoral fractures.…”

“…mL (range[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] and the nine-hole plate group was 16.3 mL (range, 8-30 mL). Descriptive statistics for volume measurements are given in…”

New Design Process for Anatomically Enhanced Osteosynthesis Plates

“…Osteosynthesis plates with high levels of anatomical compliance (i.e., plates which exhibit a small distance between bone surface and plate for a large number of patients) have been demonstrated to have numerous clinical benefits. With regard to aspects related to the surgical procedure itself, use of anatomically enhanced plate designs may allow for increased opportunities for the use of minimally invasive operative techniques . Furthermore, such plates require little to no intra‐operative bending, which is advantageous as bending has the potential to decrease the mechanical stability of the plate, which may result in an increased risk of implant failure .…”