Projects per year
MethodTwo torque screwdrivers were used consecutively by two orthopaedic surgeons to insert 60 cortical, non-locking, stainless-steel screws of 3.5 mm diameter through a 3.5 mm plate, into custom-made 4 mm thick 20 PCF sheets of Sawbone, mounted on a custom-made jig. Screws were inserted to optimal tightness subjectively chosen by each surgeon. The jig was attached to a bench for vertical screw insertion, before a further 60 screws were inserted using the first torque screwdriver with the jig mounted vertically, enabling horizontal screw insertion. Following the decision to use the first screwdriver to insert the remaining screws in the vertical position for the other variables, the following test parameters were assessed with 60 screws inserted per surgeon: without gloves, double surgical gloves, single surgical gloves, non-sterile nitrile gloves and, with and then without augmented feedback (using digitally displayed real-time achieved torque). For all tests, except when augmented feedback was used, the surgeon was blinded to the insertion torque. Once the stopping torque was reached, screws were tightened until the stripping torque was found; this being used to calculate tightness (stopping/stripping torque ratio). Screws were recorded to have stripped the material if the stopping torque was greater than the stripping torque. Following tests of normality, Mann-Whitney-U comparisons were performed between and combining both surgeons for each variable, with Bonferroni corrections for multiple comparisons.
ResultsThere was no significant (p=0.29) difference in the achieved tightness between different torque screw drivers nor different jig positions (p=0.53). The use of any gloves led to significant (p<0.001) increases in achieved tightness compared to not using gloves for one surgeon but made no difference for the other (p=0.38-0.74). Using augmented feedback was found to virtually eliminate stripping. For one surgeon average tightness increased significantly (p<0.001) when torque values were displayed from 55 to 75%, whilst for the other, this was associated with significantly decreases (p<0.001), 72 to 57%; both surgeons returned to their pre-augmentation tightness when it was removed.
ConclusionIndividual techniques make a considerable difference to the impact from some variables involved when inserting screws. However, the orientation of screws insertion and the type of screwdriver did not affect achieved screw tightness. Using visual feedback reduces rates of stripping and investigating ways to incorporate this into clinical use are recommended. Further work is underway into the effect of other variables such as bone density and cortical thickness.
|Publication status||Published - 22 Jun 2019|
|Event||2nd International Combined Meeting of Orthopaedic Research Societies - Palais des Congrès, Montreal, Canada|
Duration: 19 Jun 2019 → 22 Jun 2019
|Conference||2nd International Combined Meeting of Orthopaedic Research Societies|
|Abbreviated title||ICORS 2019|
|Period||19/06/19 → 22/06/19|
Fellowship for James Fletcher - Optimal surgical techniques to reduce screw failure in fragility fractures
14/09/18 → 13/09/19
Project: UK charity
1/02/17 → 30/09/18
Project: UK charity