Differences in Isokinetic Strength of the Knee Extensors and Flexors in Men With Isolated and Combined Cruciate-Ligament Knee Injury

in Journal of Sport Rehabilitation
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The extent of knee extensor and flexor weakness after disruption of knee ligaments affects a rehabilitation output and functional recovery and may give prognostic information on a possible risk of development of knee osteoarthritis.


The hypothesis tested was whether patients with a multiple-ligament tear would have larger abnormalities in strength of the knee extensors and flexors than patients with an isolated-ligament rupture.


Cross-sectional study, level III.


Outpatient orthopedic clinic.


3 groups of recreationally active men: noninjured control (CON, n = 12), with an anterior cruciate ligament injury (ACLI, n = 10), and with combined anterior and posterior cruciate ligament injury (APCLI, n = 9), matched according to age, body mass, and height.


All patients received conservative treatment and rehabilitation and awaited ligament reconstruction surgery.

Main Outcome Measures:

Isokinetic maximum-repetition peak torque per body mass (PT/BM) and total work (TW), PT and TW limb-symmetry index (LSI), and flexor-to-extensor PT ratio were evaluated during concentric knee extension-flexion movements at lower (60°/s) and higher (240°/s) isokinetic velocities.


The main finding was that compared with the individuals with ACLI, patients with APCLI produced in their injured limbs lower mean TW (extension: 30.3%, flexion: 28.2%) and had lower mean TW LSI (extension 74% in APCLI vs 91.6% in ACLI; flexion 61.3% in APCLI vs 90.8% in ACLI) at the higher but not lower speed of isokinetic testing. However, at the lower velocity the quantified size of reduction in PT/BM and TW was greater in subjects with APCLI than ACLI as compared with the CON individuals.


After bi-cruciate-ligament injury the capacity to produce torque by concentric muscle contractions throughout knee-extension and-flexion movements performed with high speed is lower in injured limbs than after isolated anterior cruciate ligament tear.

Kaminska, Wiernicka, and Cywinska-Wasilewska are with the Dept of Kinesiotherapy, University School of Physical Education, Poznan, Poland. Piontek is with the Rehasport Outpatient Orthopedic Clinic, Poznan, Poland. Lewandowski and Lochynski are with the Dept of Motor Rehabilitation, University School of Physical Education, Poznan, Poland.

Address author correspondence to Ewa Kaminska at kaminska@awf.poznan.pl.