PhD defense in ACL injuries
Tron Krosshaug Friday 18th of August 2006 defended his PhD "Video analysis of the mechanisms for ACL injuries" for the degree Doctor Scientiarum at Oslo Sports Trauma Research Center (OSTRC) and the Norwegian School of Sport Sciences (NIH).
| 04.08.2006 
Anterior cruciate ligament (ACL) injuries are serious and unfortunately common in several sports. To prevent such injuries, it is necessary to understand the mechanisms.
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Tron Krosshaug (26.03.73) grew up in Oslo and Telemark. He studied sports and mathematics at Telemark distriktshøgskole. He completed his Cand. Mag. degree in motion analysis/biomechanics at NIH, and finished his masters degree in the fall 2000. Tron started his PhD period at OSTRC in September 2001. Professor dr. med. Roald Bahr at OSTRC and NIH has been his main supervisor. Professor dr. med. Lars Engebretsen (OSTRC and NIH) and Professor Oddvar Hallingstad (The University Graduate Center at Kjeller) have been co-supervisors. |
Aim of the project
The aim of this PhD study was to validate existing methods for analysis of video from injury situations, in addition to develop and validate new, sophisticated methods.
Furthermore, these methods were used to analyze real injury situations. So far, the mechanisms of ACL injuries are not known. Improved methods to analyze injury situations from video will be an important step to increase our understanding of the actions leading up to the injury (i.e. playing situation and player/opponent behavior).
Video analysis may also contribute to a precise description of the biomechanics at the point of injury. This information may be important for developing preventive measures, like e.g. neuromuscular programs to improve cutting technique or modification of shoe/surface friction.
The studies
The thesis consists of four studies:
- In the first study, a new model-based image-matching technique for 3D reconstruction of human motion from video sequences was developed. The laboratory validation showed that this method was applicable for single and multiple camera views, although it was an advantage to use two or more cameras.
- In the second study, it was concluded that this method could also be applied onto real injury situations in team handball (three camera angles), basketball (four camera angles) and downhill skiing (one camera angle). Detailed biomechanical information was found in the basketball and handball situations, whereas less information could be extracted from the downhill skiing situation.
- In the third study, the traditional “visual inspection” technique (e.g. assessment of joint angles from video using no measurement tools) was evaluated. The six international experts that participated, underestimated hip and knee flexion by 7° and 18° respectively. In addition, the deviation between analysts was considerable. Our current knowledge about the mechanisms of non-contact ACL injuries originates to a large degree from video analysis. In light of this fact, the conclusions from previous studies must be assessed with caution.
- In the fourth study, 39 video situations of ACL injuries in basketball were analyzed using visual inspection. It was found that females had five times higher risk of sustaining a “valgus collapse” compared to males. In addition, the females had significantly greater hip and knee flexion at foot strike, as well as at the estimated point of injury.