Objective: To assess the diagnostic validity of an isokinetic testing to detect partial injuries on the anterior cruciate ligament (ACL). Design: Prospective diagnostic study. Settings: Orthopedic clinic, physiotherapy clinic, orthopedic hospital, and diagnostic/image clinic. Participants: Consecutive patients (n = 29) with unilateral knee complaint submitted to physical examination, magnetic resonance images (MRIs), and isokinetic testing prior to surgery of ACL reconstruction. Interventions: Not applicable. Main Outcome Measures: The isokinetic torque curves data from extensor and flexor muscles were converted to frequency domain by fast Fourier transformation and compared with healthy contralateral limb. Differences were categorized as unstable knees and these conclusions were compared with patient’s physical examinations (doctor’s conclusion on ACL integrity) and MRIs (as the radiologist conclusions on ACL integrity). After surgery, all intraoperatively confirmed partial injured patient’s data were collected. The diagnostic accuracy measures to compare the conclusions of all 3 professionals included sensitivity, specificity, positive predictive value, negative predictive value, disease prevalence, positive likelihood ratio, and accuracy—all using a confidence interval of 95%. Results: Compared with MRI, the sensitivity of isokinetic test for an ACL partial injury was 90.00%, specificity 83.33%, positive predictive value 52.94%, negative predictive value 97.56%, and accuracy 84.48%. Compared with physical examination, the sensitivity of isokinetic test for an ACL partial injury was 85.71%, specificity 78.43%, positive predictive value 35.29%, negative predictive value 97.56%, and accuracy 79.31%. Conclusions: This method of isokinetic data analysis through fast Fourier transformation can be used to improve diagnostic accuracy of a difficult detection injury. Even present, a partial ACL injury can produce a stable knee during isokinetic testing and could be used to detect candidates for conservative treatment based on strengthening exercises, reducing surgery risks, and financial and social impact on patient’s life.
Scoz is with Sports Science Program, LaB2Health—Laboratory of Biomechanics, Body Composition and Health, Department of Sport Science, Exercise and Health, University of Trás-dos-Montes and Alto Douro, Vila Real, Portugal. Scoz and Amorim are with Physiotherapy Program, Department of Physiotherapy, Universidade Cidade de São Paulo, São Paulo, Brazil. Amorim and Da Silva are with the Département des Sciences de la Santé, Programme de physiothérapie de l’université McGill offert en extension à l’Université du Québec à Chicoutimi (UQAC), Centre de recherché Intersectoriel en santé durable, Laboratorie de recherche BioNR—UQAC, Saguenay, QC, Canada. Amorim and Vieira are with the Department of Physical Therapy, Nicole Wertheim College of Nursing and Health Sciences, Florida International University, Miami, FL, USA. Mazziotti is with Physical Therapy Program, Universidade Cidade de São Paulo, São Paulo, Brazil; and the Department of Physical Therapy and Biomechanics, Paris Saint-Germain, Paris, France. Lopes is with the Department of Physical Therapy, Zuckerberg College of Health Sciences, University of Massachusetts Lowell, Lowell, MA, USA. Gabriel is with the LaB2Health—Laboratory of Biomechanics, Body Composition and Health, Department of Sport Science, Exercise and Health, University of Trás-dos-Montes and Alto Douro, Vila Real, Portugal.