In vivo application of an optical segment tracking approach for bone loading regimes recording in humans: A reliability study

Abstract

This paper demonstrates an optical segment tracking (OST) approach for assessing the in vivo bone loading regimes in humans. The relative movement between retro-reflective marker clusters affixed to the tibia cortex by bone screws was tracked and expressed as tibia loading regimes in terms of segment deformation. Stable in vivo fixation of bone screws was tested by assessing the resonance frequency of the screw-marker structure and the relative marker position changes after hopping and jumping. Tibia deformation was recorded during squatting exercises to demonstrate the reliability of the OST approach. Results indicated that the resonance frequencies remain unchanged prior to and after all exercises. The changes of Cardan angle between marker clusters induced by the exercises were rather minor, maximally 0.06°. The reproducibility of the deformation angles during squatting remained small (0.04°/m-0.65°/m). Most importantly, all surgical and testing procedures were well tolerated. The OST method promises to bring more insights of the mechanical loading acting on bone than in the past.

Hopping in hypogravity—A rationale for a plyometric exercise countermeasure in planetary exploration missions

“…Plyometric exercise—defined as movement involving repetitive and short duration-high force loading has been proposed as an effective way to load the musculoskeletal system and has been shown to improve muscle function (primarily muscle power) and bone strength even in healthy individuals [15, 16]. Peak vertical ground reaction forces (peak vertical GRF) are closely related to resultant bone deformation [17, 18] and thus strain with bone strain magnitude suggested to govern bone’s mechano-adaptation (Kriechbaumer et al, under revision). Thus, lunar countermeasures targeting (at least in part) bone maintenance should seek to involve bone strains of similar magnitude to those experienced on Earth.…”