Contribution of biomechanics, orthopaedics and rehabilitation: the past present and future.

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Abstract

[Indexed for MEDLINE] 8. Knee Surg Sports Traumatol Arthrosc. 2015 Oct;23(10):2900-8. doi: 10.1007/s00167-015-3775-5. Epub 2015 Sep 10. A mechanical pivot-shift device for continuously applying defined loads to cadaveric knees. Sena MP(1), DellaMaggioria R(1)(2), Lotz JC(1), Feeley BT(3). Author information: (1)Sports Medicine and Shoulder Surgery, Department of Orthopaedic Surgery, University of California, San Francisco 1500 Owens Ave, San Francisco, CA, 94158, USA. (2)Orthopaedic Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (3)Sports Medicine and Shoulder Surgery, Department of Orthopaedic Surgery, University of California, San Francisco 1500 Owens Ave, San Francisco, CA, 94158, USA. Brian.Feeley@ucsf.edu. PURPOSE: Current techniques to study the biomechanics of the pivot-shift utilize either static or poorly defined loading conditions. Here, a novel mechanical pivot-shift device that continuously applies well-defined loads to cadaveric knees is characterized and validated against the manual pivot-shift. METHODS: Six fresh-frozen human lower limb specimens were potted at the femur, mounted on a hinged testing base, and fitted with the mechanical device. Five mechanical and manual pivot-shift tests were performed on each knee by two examiners before and after transecting the ACL. Three-dimensional kinematics (anterior and internal-rotary displacements, and posterior and external-rotary velocities) and kinetics (forces and moments applied to the tibia by the device) were recorded using an optical navigation system and 6-axis load cell. Analysis of variance and Bland-Altman statistics were used to gauge repeatability within knees, reproducibility between knees, agreement between the mechanical and manual test methods, and agreement between examiners. RESULTS: The forces and moments applied by the device were continuous and repeatable/reproducible to within 4/10 % of maximum recorded values. Kinematic variables (excluding external-rotary velocity) were qualitatively and quantitatively similar to manual pivot-shift kinematics, and were more repeatable and reproducible. CONCLUSION: The presented device induces pivot-shift-like kinematics by applying highly repeatable three-dimensional loads to cadaver knees. It is based on a simple mechanical principle and designed using easily obtainable components. Consequently, the device enables orthopaedic biomechanists to easily and reliably quantify the effect of ACL injury and reconstruction on pivot-shift kinematics. DOI: 10.1007/s00167-015-3775-5