Eccentric kinetic chain exercise as a conservative means of functionally rehabilitating chronic isolated insufficiency of the posterior cruciate ligament

Objective: To determine the efficacy of a home eccentric kinetic chain exer cise program in improving isokinetic strength, knee function, and symtomato logy in athletes with isolated posterior cruciate ligament (PCL) injury. Design: Experimental design. Setting: Allan McGavin Sports Medicine Centre, University of British Columb ia, Vancouver, British Columbia, Canada. Participants: The study included 13 athletes with isolated PCL injury (n = 13) and 13 healthy sedentary subjects (n = 13). All participants were men a nd between 18 and 35 years of age. The,group with isolated PCL injury all h ad been diagnosed at the Allan McGavin Sports Medicine Centre, all had been treated without surgery, and had been injured at least 6 months ago. Diagn osis was based on presentation of a positive posterior sag and posterior dr awer. Intervention: The group with isolated PCL injury (treatment group) underwen t 12 weeks of eccentric kinetic chain exercise. The control group of health y sedentary individuals did not undergo any form of rigorous training durin g the course of this study. Both groups were tested for isokinetic strength , knee function, and symptomatology at weeks 0, 6, and 12. Compliance was i nsured through frequent phone contact and progressive journal records of co mpletion of daily exercise. Only those who completely executed the 12-week exercise program were included in the study. Main Outcome Measures: Hamstring and quadriceps isokinetic torque (Nm) at c onstant velocities of 60 and 120 degrees per second (degrees/s), Tegner Hop Test (meters), and Lysholm Knee Scale scores. Results: A subject-versus-treatment data analysis clearly indicated signifi cant increases in eccentric and concentric torque over the 12-week period i n the treatment group. Tegner Hop Test and Lysholm Knee Scale scores also i ncreased significantly after the eccentric squat exercise program. Quadrice ps eccentric/concentric ratios at both testing velocities increased signifi cantly after 12 weeks of rehabilitation. There were no significant differen ces in strength between extremities in the treatment group at any time duri ng the course of this study. Before rehabilitation, there were no significa nt differences between eccentric and concentric torque Values in either mus cle group (quadriceps and hamstrings) of the treatment group. After the ecc entric exercise program, the quadriceps in the injured extremity did exhibi t significantly greater eccentric than concentric torque. The treatment gro up was significantly weaker than the control group in eccentric torque at b oth testing velocities at week 0. After the 12-week exercise program, howev er, there were no significant differences between groups in eccentric quadr iceps strength. Conclusion: The results of this investigation support the eccentric squat p rogram as a viable means of functionally rehabilitating chronic PCL insuffi ciency.