A Thambyah1, P Thiagarajan, J C Goh. 1. Faculty of Medicine, Department of Orthopaedic surgery, National University of Singapore, Lower Kent Ridge Road, 119074, Singapore.
Abstract
OBJECTIVE: To compare the stiffness and maximum strength between the untwisted and twisted free-tendon. DESIGN: 22 twisted and untwisted sectioned-specimens of human cadaver patellar tendons were used and pulled to failure to obtain load-deformation profiles from which stiffness, maximum load to failure and elastic elongation limit were derived. BACKGROUND: In the reconstruction of the deficient anterior cruciate ligament, the use of the central one-third of the patellar tendon is a well-established procedure in which, prior to insertion, the tendon graft may be twisted to mimic the natural orientation of the anterior cruciate ligament in the knee joint. RESULTS: The untwisted tendons had a mean stiffness of 36.5 kg/mm (SD, 16.6 kg/mm) and maximum load of 165.9 kg (SD, 86.8 kg). With a 90 degrees twist, the average stiffness of the twisted tendon was 66.5 kg/mm (SD, 25.4 kg/mm), with maximum load at 364.5 kg (SD, 109.9 kg), an increase of over 100%. The elastic elongation limit, or allowable elongation before permanent deformation or failure, was significantly larger in twisted tendons by 35%. CONCLUSION: Twisting increased the resistance to deformation of the tendon in this study. Relevance The finding supports the surgical practice of pre-twisting tendon grafts for anterior cruciate ligament reconstruction, based on the premise that a stronger and stiffer graft provides a more favourable outcome.
OBJECTIVE: To compare the stiffness and maximum strength between the untwisted and twisted free-tendon. DESIGN: 22 twisted and untwisted sectioned-specimens of human cadaver patellar tendons were used and pulled to failure to obtain load-deformation profiles from which stiffness, maximum load to failure and elastic elongation limit were derived. BACKGROUND: In the reconstruction of the deficient anterior cruciate ligament, the use of the central one-third of the patellar tendon is a well-established procedure in which, prior to insertion, the tendon graft may be twisted to mimic the natural orientation of the anterior cruciate ligament in the knee joint. RESULTS: The untwisted tendons had a mean stiffness of 36.5 kg/mm (SD, 16.6 kg/mm) and maximum load of 165.9 kg (SD, 86.8 kg). With a 90 degrees twist, the average stiffness of the twisted tendon was 66.5 kg/mm (SD, 25.4 kg/mm), with maximum load at 364.5 kg (SD, 109.9 kg), an increase of over 100%. The elastic elongation limit, or allowable elongation before permanent deformation or failure, was significantly larger in twisted tendons by 35%. CONCLUSION: Twisting increased the resistance to deformation of the tendon in this study. Relevance The finding supports the surgical practice of pre-twisting tendon grafts for anterior cruciate ligament reconstruction, based on the premise that a stronger and stiffer graft provides a more favourable outcome.
Authors: Levent Surer; Konstantinos Michail; Murat Koken; Can Yapici; Junjun Zhu; Brandon D Marshall; Monica A Linde; Patrick Smolinski; Freddie H Fu Journal: Knee Surg Sports Traumatol Arthrosc Date: 2016-11-17 Impact factor: 4.342