What is the Effect of Vision on Movement Control in Anterior Cruciate Ligament Reconstructed Patients 7 Months Post-surgery?

The anterior cruciate ligament (ACL) is thought to have two main roles within the body: (1) providing a physical restraint to excessive rotation and forwards translation within the knee and (2) providing sensory information to the sensorimotor cortex (contributes to motor planning and motor task execution). Therefore, an ACL injury is thought to be not just a physical injury but also one which affects an individual's ability to plan and execute motor tasks. It has been suggested in previous research that following an ACL injury and even post-ACL reconstruction, individuals may become reliant on the visual-motor system when planning and executing movements. Therefore, this study aims to compare an ACLR population against healthy controls to see if it is possible to identify those who may be visually-motor reliant by accessing movement control in the absence of vision

This study will compare a male ACLR cohort against matched healthy controls. The study population will be between 18-35 year old males who are competing multi-directional field sport. The ACLR cohort will be 7 months post-surgery. The main outcome measure will be time to stability during the stepdown task (from a 20cm step). The stepdown task will be completed first with their eyes open and then with their eyes closed, thereby allowing for the creation of an index reporting how time to stability changes following the obstruction of vision. Strength and lower limb power measures will be collected as potential confounding factors.

The testing battery that participants complete are:

* visual processing ability via a sensory station which contains neurocognitive and visual acuity testing
* 3D biomechanical tests:

  1. double leg countermovement jump
  2. single leg countermovement jump
  3. double leg drop jump
  4. single leg drop jump
  5. stepdown test (eyes open and eyes closed)
  6. joint position sense test
  7. single leg balance (eyes open and eyes closed)
* isokinetic strength testing of quadriceps and hamstrings at 60deg/sec. 3 sets of 5
* questionnaires:

  1. international knee documentation committee
  2. tampa scale of kinesiophobia
  3. ACL- return to sport after injury

Eligibility Criteria:
Inclusion Criteria:

* Aged 18-35 years old
* Playing club level Gaelic football or hurling
* They must report that they intend on returning to sport at the same or higher level
* Able to give written informed consent and to participate fully in the interventions
* At 7 months biomechanical testing, individuals would need to have 70% symmetry of both quadriceps and hamstring peak torque as measured on our isokinetic dynamometer with the angular velocity set to 60°/s
* Individuals should have already commenced linear running and double leg jumping tasks as part of their rehabilitation
* They are currently attending a gym or can attain gym access for the duration of intervention period

Exclusion Criteria:

* They have not commenced running or jumping in their rehabilitation
* Revision ACL
* They underwent concurrent meniscal repair, chondral repair or extra-articular augmentation
* Serious medical conditions preventing them from completing high intensity resistance exercise
* Any previous: injuries to the visual system, concussion, head injury, unexplained seizures or epilepsy
* Any previous ankle or knee injuries
* Those who are uncomfortable or do not want to hop with their eyes closed (one of the assessment tasks will involve hopping on one leg with their eyes open and followed by another set in which their eyes are closed