Partial weight bearing of the tibia.
INTRODUCTION
Partial weight bearing is part of treatment schemes in orthopedic surgery and traumatology. The aim of the present study was to explore to what degree ground reaction forces during partial weight bearing of the lower leg are related to given instructions and to tibia deformation.


MATERIALS AND METHODS
Tibia deformation (torsion, medio-lateral and anterio-posterior bending) was measured for rear foot and forefoot loading, 10kg, 20kg and half body weight instructions compared to full loading in five healthy male subjects using the "Optical Segment Tracking" approach, a motion-capturing based method that uses monocortically fixed bone screws.


RESULTS
1. Ground reaction force was a good indicator of tibia deformation. 2. Participants significantly under-loaded during half-body weight instructions (P<0.001) while they overloaded when loading the forefoot only. 3. Partial-loading instructions led to a highly significant and systematic reduction in peak ground reaction force (GRFpk) in all three types of tibia deformation with substantial variation between measurements. 4. Forefoot usage was associated with significant, albeit moderate increases in GRFpk (P=0.0031), in AP-bending (P=0.0027) and in torsion (P<0.001), compared to rear foot loading.


DISCUSSION
These findings result in the following clinical "lessons learned": 1. GRF is a good reflection of loading-induced deformation of the tibia. 2. GRFs are hard to control by subjects/patients. 3. The expectation that forefoot-loading results in larger tibia deformation could not be confirmed in our study. 4. When aiming at a reduction in tibia deformation, rear-foot loading is more preferable than forefoot loading.
['Ganse|Bergita|B|', 'Yang|Peng-Fei|PF|', 'Gardlo|Jenny|J|', 'Gauger|Peter|P|', 'Kriechbaumer|Andreas|A|', 'Pape|Hans-Christoph|HC|', 'Koy|Timmo|T|', 'Müller|Lars-Peter|LP|', 'Rittweger|Jörn|J|']
D000328:Adult D001696:Biomechanical Phenomena D005080:Exercise Test D005545:Forefoot, Human D005684:Gait D064368:Healthy Volunteers D006801:Humans D007869:Leg Injuries D016014:Linear Models D008297:Male D011187:Posture D018709:Statistics, Nonparametric D013718:Tensile Strength D013977:Tibia D054159:Torsion, Mechanical D016138:Walking D016474:Weight-Bearing
Partial weight bearing Tibia Traumatology Lower leg Fracture Motion capturing Orthopaedic surgery Physiotherapy Unloading