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Keays S1,2, Newcombe PA3, Keays AC4
1The University of the Sunshine Coast, School of Health and Sports Sciences, Sippy Downs, Australia, 2Private Practice, Sunshine Coast, Australia, 3The University of Queensland, School of Psychology, Brisbane, Australia, 4Private Orthopaedic Practice, Nambour, Australia
Background: Anterior cruciate ligament (ACL) injuries commonly occur within families. There is some evidence that possible genetic intrinsic factors including generalized hypermobility, faulty limb alignment and narrow intercondylar notches may predispose family members to ACL injuries. It is uncertain if environmental factors common to sporting families play a role in the pathogenesis of ACL injury. This applies especially to the age of commencement of sport as it has been suggested that the increased joint laxity present at a young age makes ligaments more vulnerable. This knowledge is especially relevant as the rate of ACL injuries in children is rapidly increasing.
Purpose: This study aimed to assess whether the age of commencement of sport and the frequency of play in addition to generalized hypermobility, faulty limb alignment and intercondylar notch size would discriminate between ACL-ruptured and ACL-intact siblings.
Methods: Twenty-four ACL-injured siblings from 10 sporting families were matched for age, gender and family composition with 24 uninjured siblings from another unrelated sporting 10 families. Notch width size was assessed on intercondylar radiograph and generalized hypermobility was assessed according to Beighton's criteria. Faulty limb alignment was assessed by measuring knee hyperextension, valgus and pronation using a goniometer. Sporting history was detailed assessing type, frequency and age at commencement of sport played. A discriminant analysis was conducted to assess whether either of these genetic or environmental factors would discriminate between those siblings who did and did not have ACL injuries.
Results: Generalised hypermobility (r=.613), standing knee hyperextension (r=.637) and notch width size (r=-.544) were found to be the strongest discriminators in their ability to differentiate between siblings with and without ACL injuries. These features may be risk factors for ACL injuries in families. Valgus (r=.331) and pronation (r=.292) were not strong discriminators. Early age sport (r=.110) and frequency of sport (r=-.025) showed no ability to discriminate between injured and uninjured siblings and were not shown to be factors in ACL injury in families.
Conclusion(s): While ACL injuries are most likely multifactorial, this study suggests that intrinsic factors are more likely to predispose family members to ACL injury than environmental factors. This finding applies specially to generalized hypermobility and knee hyperextension. Frequency of sport and early exposure to pivoting sport did not discriminate those siblings with ACL injuries from those without and do not appear to be predisposing factors for ACL injury.
Implications: Both generalized hypermobility and knee hyperextension. are easily identifiable physical features. Awareness and detection of physical vulnerabilities for ACL injury mean physiotherapists could instigate dynamic stability training which has been shown to reduce the rate of ACL injury by 50%. Further investigations are required to explore other environmental factors that may put family members at risk of ACL injury and explain the rapid rate of increase in ACL injuries in children and adolescents.
Keywords: Anterior cruciate ligament, family predisposition, knee hyperextension
Funding acknowledgements: Nil
Purpose: This study aimed to assess whether the age of commencement of sport and the frequency of play in addition to generalized hypermobility, faulty limb alignment and intercondylar notch size would discriminate between ACL-ruptured and ACL-intact siblings.
Methods: Twenty-four ACL-injured siblings from 10 sporting families were matched for age, gender and family composition with 24 uninjured siblings from another unrelated sporting 10 families. Notch width size was assessed on intercondylar radiograph and generalized hypermobility was assessed according to Beighton's criteria. Faulty limb alignment was assessed by measuring knee hyperextension, valgus and pronation using a goniometer. Sporting history was detailed assessing type, frequency and age at commencement of sport played. A discriminant analysis was conducted to assess whether either of these genetic or environmental factors would discriminate between those siblings who did and did not have ACL injuries.
Results: Generalised hypermobility (r=.613), standing knee hyperextension (r=.637) and notch width size (r=-.544) were found to be the strongest discriminators in their ability to differentiate between siblings with and without ACL injuries. These features may be risk factors for ACL injuries in families. Valgus (r=.331) and pronation (r=.292) were not strong discriminators. Early age sport (r=.110) and frequency of sport (r=-.025) showed no ability to discriminate between injured and uninjured siblings and were not shown to be factors in ACL injury in families.
Conclusion(s): While ACL injuries are most likely multifactorial, this study suggests that intrinsic factors are more likely to predispose family members to ACL injury than environmental factors. This finding applies specially to generalized hypermobility and knee hyperextension. Frequency of sport and early exposure to pivoting sport did not discriminate those siblings with ACL injuries from those without and do not appear to be predisposing factors for ACL injury.
Implications: Both generalized hypermobility and knee hyperextension. are easily identifiable physical features. Awareness and detection of physical vulnerabilities for ACL injury mean physiotherapists could instigate dynamic stability training which has been shown to reduce the rate of ACL injury by 50%. Further investigations are required to explore other environmental factors that may put family members at risk of ACL injury and explain the rapid rate of increase in ACL injuries in children and adolescents.
Keywords: Anterior cruciate ligament, family predisposition, knee hyperextension
Funding acknowledgements: Nil
Topic: Sport & sports injuries
Ethics approval required: Yes
Institution: The University of Queensland
Ethics committee: Medical Research Ethics Committee
Ethics number: 2008000964
All authors, affiliations and abstracts have been published as submitted.
