| dc.description.abstract | The purpose of this study is to determine if differences exist in isokinetic knee strength between patients who are status post Anterior Cruciate Ligament (ACL) reconstruction utilizing the hamstring tendon or the patellar tendon autograft. The isokinetic strength will be evaluated using peak torque/body weight, total work and average power variables for both knee extension and knee flexion at five times during the first year status post surgery. Isokinetic assessment prompts the individual to exert as much force and angular movement as they can generate up to a predetermined velocity. As per this assessment a particular muscle group may be exercised to its maximum potential throughout the entire range of motion (ROM). Autograft versus the post ACL reconstruction using the Inclusion criteria for patients are as follows: (1) status post ACL reconstruction with either a patellar tendon or hamstring tendon autograft, (2) age 16-40 years, (3) no meniscal repairs, (4) no other ligamentous reconstructions, (5) followed standard MedSport ACL reconstruction rehabilitation protocol and (6) signed the University of Michigan Patient Information Sheet. Patients will not be included who do not meet each of the above criteria. The data will be grouped by graft type (hamstring vs. patellar tendon) and time since surgery (12-19.9, 20-26.9, 27-32.9, 33-40.9, 41-55 weeks). Statistical differences will be determined utilizing a two-sample t-test within the groups over a specific time significance set at p>0.05. This retrospective study will utilize data collected previously at patient follow up visits in the clinic. The intended state for an isokinetic test to be performed is that it is performed on a joint that has no swelling and elicits no pain when multiple stresses are applied. The patient must be able to produce maximal efforts throughout a pain free ROM. The clinic protocol for isokinetic testing requires a 10 minute warm-up on a stationary bicycle followed by a set of instructions to familiarize the patient with the equipment and what the test itself involves. The patient is then seated into the isokinetic device Biodex (Biodex Systems 2, Biodex Medical Systems, Inc. Shirley, N.Y.) and knee ROM is set from 90 degrees to 30 degrees of flexion. The uninvolved leg is tested first at 60 degrees/sec for 5 repetitions and then at 240 degrees/sec for 15 repetitions followed by the involved leg. Data results taken from the test using 60 degrees/sec only, will be used for this study. The myth that states 60 degree peak torque value represents strength while the higher velocity (240 degrees ) represents functional endurance, is one misconception of isokinetic exercise because determination of torque, work, and power is independent of test velocity.
-Torque represents the force produced about a joint’s axis of rotation
-Work is the applied force times the distance of rotation
-Power is the time required to perform work
All of these factors are involved in the assessment of strength in the knee joint either prior to ACL reconstruction surgery and/or after. The results of the Biodex test helps to give background information on how the extensors (quadriceps) and flexors (hamstrings) are altered. This study consists of subjects who used an autograft instead of an allograft. Autogfafts are tissues donated from the patients’ body, while allografts are tissues derived from cadavers. Using tissue from a cadaver has advantages like anything else as far as it elicits no risks, pain or scars from the donor site. The significance of using an allograft is that there is less discomfort post operatively and atrophy of the quadriceps muscles is greatly reduced. However, unlike using an autograft, allografts do increase the chance of infection. Men and women were tested for this retrospective study by using the above criteria to determine if there was indeed, a difference between the two different ACL reconstruction techniques. These measurements will provide valuable information regarding isokinetic strength returns for the quadriceps and hamstrings musculature for both grafts. The results of this study will assist both the medical personnel and the patients considering the graft options and different procedures available for ACL reconstruction. | |
