Effects of open versus closed kinetic chain training on knee laxity in theearly period after anterior cruciate ligament reconstruction

Knee extensor resistance training using open kinetic chain (OKC) exercise f or patients recovering from anterior cruciate ligament reconstruction (ACLR ) surgery has lost favour mainly because of research indicating that OKC ex ercise causes greater ACL strain than closed kinetic chain (CKC) exercise. In this prospective, randomized clinical trial the effects of these: two re gimes on knee laxity were compared in the early period after ACLR surgery. Thirty-six patients recovering from ACLR surgery (29 males, 7 females; age mean=30) were tested at 2 and 6 weeks after ACLR with knee laxity measured using the Knee Signature System arthrometer. Between tests subjects trained using either OKC or CKC resistance of their knee and hip extensors in form al physical therapy sessions three times per week. Following adjustment for site of treatment, pretraining injured knee laxity, and untreated knee lax ity at posttraining, the use of OKC exercise, when compared to CKC exercise , was found to lead to a 9% increase in looseness with a 95% confidence int erval of -8% to +29%. These results indicate that the great concern about t he safety of OKC knee extensor training in the early period after ACLR surg ery may not be well founded.