Sports performance in regard to prevention and return to participation is a common part of any orthopedic practice. It deals with athletes of all levels: from the elite competitor to the weekend warrior, to the client who wants to return to tennis after a Total Knee Arthroplasty. Training or rehabilitation often focuses on strengthening and motor control re-education to correct faulty movement patterns, imbalances and asymmetries. In virtually every case, functional sports testing is performed to determine if the person is ready to return to sport, and if they are at risk for re-injury. So what happens when the tests that we use to conclusively decide if a person is ready differ so greatly in the published literature? Hegedus BJSM 2015 reviewed some of the most common tests used in physical performance testing and found an extremely wide variance in several aspects of the tests reviewed.
Some of these tests included what some consider “gold standards” for return to sports play.
Tests include: Single leg hop for distance, 6 M timed hop, cross over hop for distance, single leg squat, triple jump, and single leg vertical jump. What Hegedus found was that there is a variance in the procedures in which they are applied. The warm-up and number of practice hops, number of hops recorded in the test, how the arms are used, and final scoring can be based on mean of attempts, greatest of attempts, and greatest of successful trials. So if we can’t rely on standardized testing that has poor reliability at the present time, the importance of movement analysis and motor control becomes magnified!
Often testing against the non-involved leg makes the assumption that the uninvolved side avoided injury because it was the stronger or more stable side …an assumption that has been proven false by far too many people who have torn ACL’s in both knees.
Also, joint forces and other additional elements play a role in ACL or knee injuries, therefore, focusing solely on lower limb kinematics in classifying injury risk or post-injury rehab may not encapsulate all relevant factors. Even attempting to examine “normal” in the attempt to standardize kinetic motions for populations and translate that data into risk factors has come up short in developing a predictability rule of sorts for determining return to participation (Fox, Sports Med 2014)
This comparison suggests that at the time of testing, athletes, regardless of being cleared for return to sport, were deficient in dynamic control and therefore at risk of injury. Furthermore, asymmetries across both groups suggest that these deficiencies likely existed before the initial ACL rupture and may have been associated with the initial injury. Routine examination or sports testing of the lower limb may not pick up on neuromotor control deficits that may be compensated for and missed during clinical evaluation but may be contributing to abnormal movement patterns increasing the re-injury risk. Clinical impairment measures do not appear to be related to measured functional ability. Performance of both functional tests, FMS, and YBT-LQ at 6 months would suggest that the typical patient in both groups would be at a greater risk of lower extremity injury (AJSM 2015).
Also, quadriceps ECC strength was more directly correlated to JPS than concentric strength in patients with PFPS. This suggests inhibition or weakness of the type II muscle fibers that are responsible for maintaining the eccentric muscle force during movement. The link can be made between quadriceps ECC strength, proprioception and pain in this population (Knee Surg Sports 2015). But simply improving strength neither guarantees non-injury or addresses other factors that could contribute to injury occurring. Video replay and/or video analysis has shown some promise to help aide athletes to improve their joint positional sense. But, video replay lacks the immediate visual feedback that has been proven to enhance motor learning skill acquisition.
There are numerous expert clinicians in the field of sports rehabilitation capable of skillfully attempting to determine when a patient or athlete is ready to return to dynamic function, and often times the individual is able to return without future injury. I have spoken with colleagues who’s preferences range from using the ECC step down testing to return an OL in college football to play, to using a barrage of physical performance tests to acquire as much information as possible to make the determination. However, what about the clinician who is deemed with the task of determining a patients suitability to return to participation without the expert knowledge base? Surely they cannot rely on functional based sport testing for the lower extremity. So what resources can they rely on? Unfortunately, the most realistic answer is devoting the time to become an educated clinician, and skilled movement analyst. The maximum amount of information must be acquired to help determine when someone is ready to return to participation. NOT solely relying on the hard numbers and pass criteria that are suggested in sports testing models. Use all resources that are available to you such as sports psychology assessments, visual feedback training with the Motion Guidance system to help the patient better understand what biomechanics are occurring during actions in real-time feedback and help the clinician get sport specific information during those actions, and consider need for extra motor learning time as well as strength and conditioning. It has been suggested that advancing patients through the stages of motor learning and eventually giving external cues for function will facilitate transfer of motor control to subcortical regions of the brain and free cortical resources from programming more complex actions. Also incorporating visual-motor control training into rehabilitation will decrease the reliance of visual feedback to make dynamic changes in muscle function during an open environment (JOSPT 2015).
Each of these must be individually applied to each individual case in order to continue to decrease the risk of injury after return to play.
Eric M. Dinkins, PT, MSPT, OCS, Cert MT, MCTA