Essay Instructions: ARTICLE:
Journal of Biomechanics 41 (2008) 498–505
Effect of ski boot settings on tibio-femoral abduction and rotation during standing and simulated skiing Harald Bo¨ hm, Veit Senner Department of Sports Equipment and Materials, Faculty of Sport Science, TU Munich, Connollystr. 32, D-80809 Munich, Germany
Accepted 25 October 2007
Abstract
Ski boots are signed to transfer high forces from the skier to the ski. For this purpose they are ma of stiff materials and constrain the leg of the skier to an unnatural position. To overcome the problem of unnatural knee posture, the ski boots can be adjusted in the frontal plane as well as in the horizontal plane by the canting mechanism and the ‘‘v-position’’, respectively. Canting enables lateral and
medial orientation of the shaft with respect to the base of the boot. The ‘‘v-position’’ is a pronounced outward rotation of the boot’s base with respect to the ski’s long axis. The purpose of this study is to investigate the effect of different foot rotations and ski boot canting
settings on knee kinematics during standing and simulated skiing. Knee kinematics was measured by means of motion analysis and with the help of skin-mounted markers on 20 subjects.
The ski boots in their standard settings significantly constrained the skier to an unnatural valgus position. Ski boot base rotation had a significant effect on internal external knee rotation, whereas canting had an effect on varus–valgus angles during standing. However, for
the simulated skiing position no effects were observed. The study suggests that the constraints of the ski boots result in a clinically relevant valgus misalignment. Canting settings reduced the misalignment but only by about 10%. Increased ski boot canting settings
would therefore be sirable. Knee kinematics showed that rotational misalignment could not be linked to any significant increase in injury risk.
r 2007 Elsevier Ltd. All rights reserved.
Keywords: Knee; Rotation; Varus and valgus; Ski boot; Canting
1. Introduction
Ski boots are ma of stiff materials to transfer high
forces from the skier to the ski (Maxwell and Hull, 1989).
The drawbacks of stiff ski boots are that they constrain the
skier’s leg to an unnatural position, e.g. a skier with natural varus leg alignment is forced to a valgus movement in orr to preserve parallelism of the ski to the ground (Corazza and Cobelli, 2005). Possible consequences of knee varus or valgus misalignment might be overuse injuries (Sharma et al., 2001, Teichtahl et al., 2006). Tibia-femoral rotation also alters the tibio-femoral articular cartilage contact points. This might change contact stress distributions in the cartilage and predispose the joint to generative changes (Li et al., 2006, Andriacchi et al., 2006). These long-term overuse effects of skiing in an unnatural position are difficult to assess, but viations from normal posture are commonly taken as a risk factor for overuse injuries (Issa and Sharma, 2006). In addition to the risk of long-term overuse injuries, the risk of acute ACL ligament ruptures might be increased through knee Disalignment. In dynamic landing movements, it has been shown that neutral limb alignment compared to varus or valgus reduces the possibility of ACL rupture through a valgus or varus opening mechanism (Chaudhari and Andriacci, 2006). A less severe but very common knee injury is the
patellofemoral pain syndrome (PFPS). Muscular
imbalance of the lower extremity is one of the major
contributing factors (Thomee et al., 1999). It might be
speculated that knee misalignment, caused by the ski boot,
places extra pressure on the muscles around the knee
and possibly exaggerates muscle imbalances and patella
grinding. ARTICLE IN PRESS
www.elsevier.com/locate/jbiomech
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0021-9290/$ - see front matter r 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jbiomech.2007.10.019
Corresponding author. Tel.: +43; fax: +42.
E-mail address: (H. Bo¨ hm).
PROJECT SUMMARY:
Project
Review of Biomechanical Analysis Literature
Find, read, and critically review an article from research and/or coaching literature that analyzes a sport or rehabilitation movement technique with which you are familiar. The article should compare two (or more) ways to accomplish the movement or scribe one way to perform the movement.
The analysis should consist of six parts:
1. Introduction
2. Article summary
3. A subjective evaluation of the article
4. Biomechanical scription of the technique
5. Critical analysis of the technique selected
What is the best way to perform this movement and why?
6. Summary
Goals for the assignment:
o Experience real investigative scholarship within biomechanics.
o Develop a sense of authority over a specific topic in biomechanics.
o Practice intifying and pursuing a significant question.
o Experience synthesizing material from a variety of sources.
o Exposure to professional literature in biomechanics.
o Practice using library resources, research methods, and systems of documentation.
Milestones:
o Proposal:
One paragraph scription of the topic and why it was selected
o Introduction and selected article
One page introduction of the topic, why it was selected and how the chosen article fits the topic; also provi a copy of the article
o Rough draft
All components of the review are to be completed
o Final draft
Due Dates:
o Proposal – 2/14
o Introduction and article summary – 3/6
o Rough draft – 4/3 (to be submitted via Safe Assignment on the course Blackboard web page)
o Final draft – 4/24 (to be submitted via Safe Assignment on the course Blackboard web page)
RUBIC:
Author: _____________________ Title of piece: _________________________ Date: ________
Gra: __________
EXCELLENT VERY GOOD ADEQUATE FAIR POOR
4 3 2 1 0
(1) Review of literature is cohesive, _____ _____ _____ _____ _____ complete and formatted correctly.
(2) Biomechanical scription _____ _____ _____ _____ _____ of the technique is clear and correct.
(3) Justification of selection _____ _____ _____ _____ _____ of technique is clear and found on sound principles.
(4) Provis aquate _____ _____ _____ _____ _____ supporting arguments, evince, examples, and tails.
(5) Responds fully to the _____ _____ _____ _____ _____ assignment.
(6) Expresses its purpose _____ _____ _____ _____ _____ clearly and persuasively.
(7) Is directed toward and _____ _____ _____ _____ _____ meets the needs of a fined audience.
(8) Begins and ends effectively. _____ _____ _____ _____ _____
(9) Is well organized and unified. _____ _____ _____ _____ _____
(10) Uses appropriate, direct language. _____ _____ _____ _____ _____.
(11) Correctly acknowledges _____ _____ _____ _____ _____ and documents sources.
(12) Is free of errors in _____ _____ _____ _____ _____ grammar, punctuation, word choice, spelling, and format.
(13) Maintains a level of _____ _____ _____ _____ _____ excellence throughout.
(14) Shows originality and _____ _____ _____ _____ _____ creativity in realizing (1) through (10).
OVERALL EVALUATION EXCELLENT VERY GOOD ADEQUATE FAIR POOR
COMMENTS:
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