Adequacy of in-mission training to treat tibial shaft fractures in mars analogue testing

Abstract

Long bone fractures are a concern in long-duration exploration missions (LDEM) where crew autonomy will exceed the current Low Earth Orbit paradigm. Current crew selection assumptions require extensive complete training and competency testing prior to flight for off-nominal situations. Analogue astronauts (n = 6) can be quickly trained to address a single fracture pattern and then competently perform the repair procedure. An easy-to-use external fixation (EZExFix) was employed to repair artificial tibial shaft fractures during an inhabited mission at the Mars Desert Research Station (Utah, USA). Bone repair safety zones were respected (23/24), participants achieved 79.2% repair success, and median completion time was 50.04 min. Just-in-time training in-mission was sufficient to become autonomous without pre-mission medical/surgical/mechanical education, regardless of learning conditions (p > 0.05). Similar techniques could be used in LDEM to increase astronauts' autonomy in traumatic injury treatment and lower skill competency requirements used in crew selection.

Figure 1

Organization and crossmatch of all operators depending on their skill group and the different learning conditions. Astronauts were divided into 3 groups according to their educational background. Anat: analogue astronauts skilled in human anatomy (studies in the medical or biomedical field but not in surgery), Meca: knowledge of mechanics, stability, forces movements and constraints (engineers), Others: no prior knowledge of either anatomy or mechanics. Learning conditions included standard conditions and stressful conditions (unexpected moment and during EVA: Extravehicular Activity).

Figure 2

Creation of the fractured leg model. Indication of the fracture line with a laser (a – red line). Bone cutting by the diamond bandsaw following the fracture line (b). Soft tissues assembly and fixation around the fractured bone, mounted on a foot prosthesis (c). Final fractured leg model (d).

Figure 3

Material needed to build the EZExFix (a). Final construct mounted on a broken artificial leg on a frontal, sagittal and upper view (b). Broken artificial leg after removing soft tissues ready to measure analysis parameters on a frontal, sagittal and upper view (c).

Figure 4

Incidence of safe zones failure among the 24 operations. Horizontal lines indicate the metaphyseal limit and vertical lines demarcate the safe surface between the tibial crest and the medial border of the tibia surrounding the anteromedial side of the tibia.

Figure 5

Incidence of steps success/failure among the 24 astronauts’ operations taking all sub-criteria into account (a) and repartition of success/failure following each sub-criterion (b). Both main sub-criteria to ensure a healthy evolution are font coloured in orange. Incidence of steps failure among the 24 astronauts’ operations when only main sub-criteria are considered (c).

Figure 6

Boxplots of time taken by astronauts depending on steps (a). Center line: median, box limits: upper and lower quartiles, whiskers: 1.5 × interquartile range, °: outliers, Min: minutes, *: p < 0.05, ****: p < 0.0001 from one-way ANOVA test. Graphs of absolute and relative means of time for each stacked step depending on groups (surgical control or astronauts) (b). Dotted grey lines (…): lines connecting steps between both groups suggesting a difference when lines are not parallel between lower and upper border of a step or a similarity if both lines are parallel. Min: minutes, ns: non-significant. Strip chart of time required for each step depending on educational background (c). The different educational background between astronauts did not affect neither the total time (p = 0.904) nor the time at each step (p = 0.396, p = 0.961, p = 0.669, p = 0.340 from step 1 to 4 respectively) following the one-way ANOVA test. Min: minutes. Bars: medians.