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Keays S.L.1, Newcombe P.A.2, Bullock-Saxton J.E.3
1The University of the Sunshine Coast, School of Health and Sport Sciences, Sippy Downs, Australia, 2The University of Queensland, School of Psychology, Brisbane, Australia, 3Active Rehabilitation Physiotherapy, Research Manager & Clinical Educator, Brisbane, Australia
Background: The major deficit following anterior cruciate ligament (ACL) injury is knee joint instability. Instability may be assessed objectively using clinical or instrumented measures or subjectively expressed as the perception of how stable the knee feels. There is a paucity of specific subjective measures for ACL functional instability. For this reason there is little correlation between subjective and objective tests in the ACL literature. Other questionnaires assessing knee stability do not specifically assess activities that challenge antero-lateral rotatory instability (ALRI) which characterizes ACL deficiency.
Purpose: The aim of this study was to investigate whether a short subjective questionnaire assessing progressively demanding activities challenging ALRI would correlate with objective ACL measures in patients with ACL deficiency. This devised questionnaire was called the Trust Questionnaire and was developed because patients with ACL deficiency frequently expressed that they did not trust their injured knee.
Methods: Twenty-four participants with chronic ACL deficiency took part in this study. These included 16 males and eight females who were on average aged 29 years. All had been diagnosed as ACL ruptured by an orthopaedic surgeon, on arthroscopy or MRI. The participants underwent objective antero-posterior (AP) stability testing at 10, 15 and 30lb force (KT 1000 dynamometer), as well as functional performance testing (shuttle run, side-step, carioca test and single hop tests) and quadriceps and hamstring strength testing at 60 degrees/second (Cybex 11). They completed the Trust Questionnaire. Correlational studies using Spearman´s rho were conducted in order to assess the relationship between the Trust Questionnaire and the KT1000, the functional performance and the strength scores.
Results: Significant (or very close) correlations were found between the Trust questionnaire and the KT1000 measures at 10lbs pressure (r=-.401, p=.052), the shuttle run (r=-.365, p=.06) the carioca test (r=-.408, p=.048) as well as quadriceps (r=461, p=.023) and hamstring side-to-side strength (r=.582, p=.004).
Conclusion(s): The Trust questionnaire correlated with two functional performance tests. Importantly it was also shown to correlate with passive KT1000 stability testing at 10lb force, indicating that the more movement present when subjected to low AP loads the less stable and trustworthy the knee felt. Researchers are continually seeking to identify a measure where active stability relates to passive stability. Interestingly, the objective measure that correlated most with the Trust score was muscle strength. The greater the quadriceps and hamstring strength the higher the level of trust.
Implications: The Trust questionnaire is a quick simple tool that correlates with quadriceps and hamstring strength and functional performance. Most importantly it reflects the level of passive stability present as measured objectively on the KT1000 at 10lbs force. It is suggested that this is a very useful measure of functional stability in ACL injured individuals and can be used as a routine assessment tool as well as to measure improvement following physiotherapy or surgery.
Funding acknowledgements: Nil
Topic: Sport & sports injuries
Ethics approval: The University of Queensland. Approval Number 2008000864. This is part of a large ongoing study
All authors, affiliations and abstracts have been published as submitted.
