A PhD student from Loughborough University whose research was supported by NRC funding has already won multiple awards for her work and has been published in an international journal.
Tamara Valenčič has been exploring the long-term effects of anterior cruciate ligament reconstruction (ACLR) using a hamstring tendon graft on the neural control of the knee extensor and flexor muscles.
As a result of her reseach, she has already been published in the Journal of Applied Physiology - part of the American Physiological Society - and has won three awards for her work.
These include the Doctoral Researcher Support Fund Award from Loughborough Doctoral College which enabled her to travel to Japan for the International Society of Electrophysiology & Kinesiology Congress, and first prize in two poster competitions run by The Physiological Society and the NRC Rehabilitation Technologies Conference.
Tamara's findings showed that ACLR individuals exhibit a reduced ability to increase the neural signal to the quadriceps muscles of the affected leg, even years after surgery. This deficit persists despite seemingly full recovery of quadriceps strength and size, and appears unaffected by the knee angle.
Her research discovered that in the knee flexor muscles, the speed at which the knee flexors of the affected leg could be activated and exert their available force (i.e., explosive strength) appeared unaffected by hamstring-tendon ACLR. This was despite a marked weakness of the knee flexor muscles in a flexed knee position, likely driven by the graft-donating muscle becoming shorter and smaller after surgery. Additionally, during low-intensity contractions, the nervous system appeared to adapt its control of the hamstrings, potentially to compensate for their structural and likely biomechanical changes after ACLR.
Overall, these findings suggest that ACLR with a hamstring tendon graft leads to chronic between-limb imbalances in the strength and neural control of the knee muscles. Interestingly, while the quadriceps appear predominantly affected by the ligament injury and reconstruction, the hamstrings appear principally affected by the tendon harvest itself.
This highlights the long-lasting impact of not only ACLR, but also graft-donor site morbidity on neuromuscular function of the affected knee, suggesting that the long-term implications of ACLR may be graft-specific.