|Injury Mechanisms for ACL Injuries in Team Handball - A Video Analysis|
ACL injuries are very comrnon in Norvegian team handball, in particular among female players (Myklebust et al 1998). Studies based on interviews of injured players show that rnost of the injuries occur in a rnovement the players have done many times before, oflen in a faking/cutting movement or Ianding from a jump, and apparently without direct body-contact. However, observational studies of the iniury, mechanisms for ACL injuries are currently not available. The purpose ofthis study was to anaiyze the injury mechanisms for ACL injuries in fernale players based not only on player recalì, but also analysis of video-taped injury situations.
ACL injuries in 60 semi-professional or amateur teams (920 players) in the three upper divisions for women in Nonvegian team handball were recorded during the 1998-99 season. All the injured players were interviewed personally or on the telephone based on a standardized questionnaire. Videos of ACL injuries were also collected through a systematic search of Norwegian TV station archives and through contacts in the handball environment. The videos were digitized and enhanced to clearly show the accident. Three knee expefls (MDs with ACL research experience) and three handball experts (national team coaches) analyzed the videos independently in order to describe the injury mechanisms and playing situations.
We found 32 ACL injuries during the 1998-99 season. Of these injuries, 24 (75%) occurred during competition, 27 (84%) in the attacking phase, 19 (59%) in a plant & cut fake movement, and six (19%) when landing from a jump shot. In twenty (63%) of the cases the athletes reported that there was no player contact when they were injured.
We were able to locate 12 videos of ACL injuries from Nonvegian or international competition from the period 1988-99, five of these were from the last season. Of these 12 injuries, 11 (92%) occurred in the attacking phase. Two main injury, mechanisms were identified from video analysis, nine injuries (75%) resulted from a plant & cut fake movement and two (17%) when landing from a jump shot.
Thus, the video injuries appear to be a representative sample when compared with the questionnaire data. In all the video cases the foot was planted on the floor at the time of injury, and in ten cases the foot was planted far outside the knee.
The coaches described eight of the playing situations as unusual. Five of the players were in opponent contact just before the injury occurred (four were pushed), and four were in opponent contact at the time of injury (three were pushed). Of the nine plant & cut fakes, five were two-legged and four one-legged. In all nine cases, the knee was in slight flexion (5-15°) and valgus at the time of injury, combined with external rotation of tibia in five cases and internal rotation in four cases. Seven did a right-left fake, five of these had right side injuries. In both of the two jump shot landing injuries take-off and landing were done using the injured leg, and both landed with the knee in extension (0°), valgus, and external rotation of the tibia.
Player interviews and video analysis both revealed two main injury mechanisms for ACL. The most usual injury mechanism, a plant & cut faking movement, occurred in every case with a forceful valgus-extemal or -internal rotation with the knee in slight flexion. Contrary to what players reported when interviewed, the movement appears to have been influenced by external forces, like a push from an opponent. The other main injury mechanism, a one-legged jump shot landing, occurred with forceful valgus-external rotation with the knee fully extended. In both the two injury mechanisms the foot was planted on the floor and in nearly all cases the foot was far outside the knee.
The project was supported by the Norvegian Handball Federation and Storebrand insurance.