Is There a Role for GPS in Determining Functional Ankle Rehabilitation Progression Criteria? A Preliminary Study

Greig, M., Emmerson, H., McCreadie, J.

Context:
Contemporary developments in GPS technology present a means of quantifying mechanical loading in a clinical environment with high ecological validity. However, applications to date have typically focused on performance rather than rehabilitation.

Objective:
To examine the efficacy of GPS micro-technology in quantifying the progression of loading during functional rehabilitation from ankle sprain injury, given the prevalence of re-injury and need for quantifiable monitoring. Furthermore, to examine the influence of unit placement on the clinical interpretation of loading during specific functional rehabilitation drills.

Design:
Repeated measures.

Setting:
University athletic facilities.

Participants:
22 female intermittent team sports players.

Intervention:
All players completed a battery of 5 drills (anterior hop, inversion hop, eversion hop, diagonal hop, diagonal hurdle hop) designed to reflect the mechanism of ankle sprain injury, and progress functional challenge and loading.

Main Outcome Measures:
GPS-mounted accelerometers quantified uni-axial PlayerLoad for each drill, with units placed at C7 and the tibia. Main effects for drill type and GPS location were investigated.

Results:
There was a significant main effect for drill type (P < 0.001) in the medio-lateral (ɳ^2 = 0.436), anterio-posterior (ɳ^2 = 0.480), and vertical planes (ɳ^2 = 0.516). The diagonal hurdle hop elicited significantly greater load than all other drills, highlighting a non-linear progression of load. Only medio-lateral load showed evidence of progressive increase in loading. PlayerLoad was significantly greater at the tibia than at C7 for all drills, and in all planes (P < 0.001, ɳ^2 ≥ 0.662). Furthermore, the tibia placement was more sensitive to between-drill changes in medio-lateral load than the C7 placement. Conclusions: The placement of the GPS unit is imperative to clinical interpretation, with both magnitude and sensitivity influenced by the unit location. GPS does provide efficacy in quantifying multi-planar loading during (pre)rehabilitation, in a field or clinical setting, with potential in extending GPS analyses beyond performance metrics to functional injury rehabilitation and prevention.

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