# Analysis of 2.0 and 3.5 mm Cortical Bone Screw Dimensions

## TL;DR

This study found that many veterinary bone screws have inconsistent dimensions, which could affect their performance in surgeries.

## Contribution

The study reveals significant dimensional inconsistencies in veterinary bone screws, emphasizing the need for better quality control.

## Key findings

- 28.6% of 2.0 mm screws and 75% had pitch measurements outside tolerance ranges.
- 3.5 mm screws showed 44% of major diameter and 26% of pitch measurements outside tolerance.
- Dimensional variation was common along the length of individual screws.

## Abstract

Bone screws are essential components of veterinary orthopedic surgery, yet their manufacturing quality is rarely evaluated. In this study, we assessed the dimensional accuracy of commonly used stainless-steel cortical screws. Measurements of major diameter and thread pitch were compared with established tolerance ranges. We found notable inconsistencies both within individual screws and between screws of the same size. Many screws did not meet standard dimensional tolerances, and variation along the length of single screws was common. Such irregularities may reduce screw–bone stability and impair clinical outcomes. These findings emphasize the need for improved quality control in the production of veterinary orthopedic implants.

Investigation and quality assessment of veterinary orthopaedic implants are seldom undertaken, despite their critical role in clinical outcomes. Dimensional accuracy is particularly important for screw–bone interface stability. This study aimed to evaluate the dimensional consistency of commonly used veterinary bone screws. Sixty unused stainless steel cortical screws (2.0 mm and 3.5 mm) were randomly selected from larger batches. Each screw was examined microscopically, and six measurements were obtained from three distinct regions along the screw length. Major (outer) diameter and pitch were recorded and compared against standard tolerance ranges. For 2.0 mm screws, 28.6% of major diameter and 75% of pitch measurements were outside the tolerance range. For 3.5 mm screws, only 56% (major diameter) and 26% (pitch) of measurements fell within tolerance. With the exception of the major diameter of the 2.0 mm screws, most screws exhibited dimensional variation along their length. This study demonstrates considerable variability in screw dimensions within and between individual screws of the same classification. While tolerance ranges are expected between different screws, dimensional uniformity is essential along the length of a single screw. The observed variability indicates suboptimal manufacturing quality, which may compromise screw–bone interface integrity and clinical performance. These findings highlight the need for improved quality control in the production of veterinary orthopaedic implants.