Principal Investigator: Thomas P. Andriacchi, PhD Objective: This is a study of the functional adaptations associated with anterior cruciate ligament (ACL) injury and reconstruction. The long-term goal of this project is to provide information that can be applied to the prevention and treatment of injury to the ACL of the knee. Specific Aims Aim1: Hypothesis: Patients that develop adaptive changes in the balance between quadriceps and knee flexor action will have a lower magnitude of overall anterior posterior (AP) displacement. Aim2: Hypothesis: The degree of functional adaptation defined by the reduction (from normal) in the net quadriceps moment during walking will be correlated with knee extensor anatomy. Progress during 2006 The work performed during the previous year has expanded our understanding of the relationship between adaptations in net knee extensor moments and alterations in AP displacement of the tibia in the ACL deficient knee. Although a net reduction in knee extensor force appeared to be beneficial during walking, our results indicate that these adaptations may have different effects during other activities. ACL deficient subjects show similar adaptations toward net quadriceps reduction during stair climbing, but these reductions cause AP displacements that are further from normal. Patients who maintain net quadriceps activity close to the levels of the uninjured contralateral side experience more normal AP displacements during stair climbing. Another major finding has been that the degree of functional adaptation in the net quadriceps moment during walking is correlated with knee extensor anatomy in the ACL deficient knee, while no such relationship exists in the uninjured contralateral limb. ACL deficient knees with greater patellar ligament insertion angle, a more horizontal orientation of the patellar ligament relative to the long axis of the tibia, demonstrated reduced quadriceps usage during walking. Our results from a three-dimensional knee model support this observation by demonstrating that the sensitivity of anterior tibial translation to quadriceps contraction is several times higher in ACL injured knees than in intact ACL knees. The observation of kinematic alterations in ACL deficient patients led us to explore the relationship between knee kinematics and tibiofemoral cartilage thinning in the ACL deficient knee. Our results indicate that the regional cartilage thinning could be correlated with the shift in the knee kinematics during walking. Additionally, our results demonstrate that surgical reconstruction of the ACL fails to restore the kinematics of the knee. The early analysis indicates that ACL reconstructed knees are more externally rotated relative to the contralateral knee during walking. Plan for Subsequent Years The plans for the next year involve acquiring additional data on ACL deficient and ACL reconstructed patients. Subjects will be evaluated according to the previously defined protocols to address both specific aims of this study. We will continue to acquire MR images that will be used to measure the orientation of the ACL graft in the ACL reconstructed knees and quantify cartilage morphological changes following ACL injury. These results will provide a valuable complement to the existing protocol. Publications Andriacchi T, Briant P, Bevill S, Koo S: Rotational changes at the knee after ACL injury cause cartilage thinning, Clinical Orthopaedics and Related Research (Virtual Reality in Orthopaedic Surgery symposium), Jan 442:39-44, 2006. Chaudhari, A, Andriacchi, T: The mechanical consequences of dynamic frontal plane limb alignment for non-contact ACL injury, J Biomechanics, 39(2):330-8, 2006. Chaudhari, A, Andriacchi, T: Comment: effect of fatigue on knee kinetics and kinematics in stop-jump tasks. Amer J Sports Med. Feb;34(2):312; author reply 313-5, Feb 2006. Chaudhari A, Lindenfeld T, Andriacchi T, Noyes, F: Knee and hip loading patterns at different phases in the menstrual cycle: implications for the gender difference in ACL injury rates. American Journal of Sports Medicine, accepted for publication, Sep 2006. Chaudhari A, Andriacchi T: The initiation and progression of osteoarthritis after ACL injury, Medicine & Science in Sports & Exercise, in review, December 2006. Shin C, Chaudhari A, Andriacchi T: The influence of deceleration forces on ACL strain during single leg landing: a simulation study. Journal of Biomechanics, (Epub ahead of print, June 22, 2006). Shin CS, Chaudhari AM, Dyrby CO, Andriacchi TP: The patella ligament insertion angle influences quadriceps usage during walking of anterior cruciate ligament deficient patients, Journal of Orthopaedic Research, in review, November 2006. Scanlan SF, Chaudhari AM, Andriacchi TP: Relationship between tibiofemoral kinematics and compensatory moments during stair ascent for the ACL deficient knee, Journal of Orthopaedic Research, submitted for publication, June 2006. Presentations Andriacchi Keynote Lecture: 2006 American College of Sports Medicine Annual Meeting (ACSM), Steadman Hawkins Foundation, Featured Science Session entitled The structure and function of articular cartilage and the initiation, progression, treatment and rehabilitation of knee osteoarthritis; Keynote Lecture Title: “Biomechanical Framework for the In Vivo Initiation and Progression of Knee Osteoarthritis”, Denver, CO, May 31- June 3, 2006. Andriacchi Guest Speaker: Bay Area Knee Society Conference, Symposium: Knee Arthritis Following Sports Injury: Current Concepts. Topic title: “The patho-mechanics associated with development of knee arthritis following ACL injury”, San Francisco, CA, September 29- 30, 2006. Sean Scanlan, Ajit Chaudhari, Chris Dyrby, Thomas P. Andriacchi: Compensatory muscle moments in ACL-deficient subjects reduce anterior tibial translation during stair ascent, 52nd Annual meeting of the Orthopaedic Research Society, Chicago, IL, March 19-22, 2006. S. Iwata, Y. Suda, T. Nagura, H. Matsumoto, T. Otani, Y. Kiriyama, Y. Toyama, T. Andriacchi: Knee laxity in extension relates subjective symptoms in isolated PCL deficient knees, 52nd Annual meeting of the Orthopaedic Research Society, Chicago, IL, March 19-22, 2006. Seungbum Koo, Thomas P. Andriacchi: Time, BMI and gender influence spatial patterns of tibial cartilage degeneration after ACL rupture, ASME Bioengineering Conference, Amelia Island, FL, June 21-25, 2006. Choongsoo Shin, Ajit Chaudhari, Thomas P. Andriacchi: The effect of lateral tibial tunnel movement of single bundle ACL reconstruction and the effect of double bundle reconstruction on the internal rotation during dynamic single-leg landing, ASME Bioengineering Conference, Amelia Island, FL, June 21-25, 2006. Ajit Chaudhari, Seungbum Koo, Sean Scanlan, Thomas P. Andriacchi: ACL graft sagittal plane orientation influences anterior-posterior tibial translation during walking, ASME Bioengineering Conference, Amelia Island, FL, June 21-25, 2006. Ajit Chaudhari, Sean Scanlan, Thomas P. Andriacchi: ACL reconstruction does not fully restore knee kinematics during walking, ASME Bioengineering Conference, Amelia Island, FL, June 21-25, 2006. Seungbum Koo, Thomas P. Andriacchi. The knee joint pivots on the lateral compartment during ambulation, American Society of Biomechanics Meeting, Blacksburg, VA, September 6-9, 2006. Funding Source: NIH
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