Open- or Closed-Kinetic Chain Exercises After Anterior Cruciate Ligament Reconstruction?

Braden C. Fleming; Heidi Oksendahl; Bruce D. Beynnon

Disclosures

Exerc Sport Sci Rev. 2005;33(3):134-140. 

In This Article

Abstract and Introduction

Open-kinetic chain (OKC) and closed-kinetic chain (CKC) exercises may not differ in their effects on the healing response of the anterior cruciate ligament (ACL)-reconstructed knee. Recent biomechanical studies have shown that the peak strains produced on a graft are similar. Clinical studies suggest that both play a beneficial role in the early rehabilitation of the reconstructed knee.

The optimal rehabilitation program after anterior cruciate ligament (ACL) reconstruction has changed considerably over the past 20 yrs. Accelerated rehabilitation programs, which permit early ROM, immediate weight-bearing, and early return to sport, have become the accepted standard. The trend toward accelerated rehabilitation, however, has been based primarily on clinical perception, retrospective observations, and the patients' desire to return to full activity quickly-not on prospective randomized controlled trials. The optimal rehabilitation program after ACL reconstruction remains undetermined.

One of the goals of postoperative rehabilitation is to restore range of knee motion and muscle strength to the injured knee, while protecting the healing graft from forces that could permanently deform it. It is generally thought that the biomechanical environment of the healing graft can be optimized by prescribing "closed kinetic chain" (CKC) exercises and avoiding open kinetic chain (OKC) exercises early in the rehabilitation program. CKC exercises have been justified for early rehabilitation, in part, because they: 1) reduce the anterior-directed intersegmental forces that act on the tibia relative to the femur;[2,5,6,8,9,12] 2) increase tibiofemoral compressive forces;[5,6,8,9] 3) increase cocontraction of the hamstrings;[2,7,12] 4) mimic functional activities more closely than OKC exercises;[6,10] and 5) reduce the incidence of patellofemoral complications.[5,6,10]

Despite the frequent use and acceptance of the OKC and CKC terminology, a variety of definitions can be found in the literature. For the Purpose of this article, we defined OKC exercises as those in which the foot is not in contact with a solid surface. The resistive loads are applied to the tibia and transferred directly to the knee (Fig. 1). Only the muscles spanning the knee are required to perform the exercise. Leg extension exercises and kicking are examples of OKC exercises. We defined CKC exercises as those in which the foot is in contact with a solid surface. The foot is opposed by a ground reaction force, which is transmitted to all of the joints in the lower extremity (Fig. 1). Muscles spanning all of the joints of the lower extremity are used. Examples of CKC exercises are the squat, leg press, and lunge.

The critical difference between OKC and CKC exercises is not the kinematic arrangement but the resultant loads transmitted to the knee. For OKC exercises, the resistive load (WLG) is applied to the tibia and transmitted to the knee (TK). For CKC exercises, the ground reaction force (FG) is transmitted to all the joints of the leg (TA, TK, and TH).

In this brief review article, we explore the hypothesis that OKC and CKC for the rehabilitation of the ACL-reconstructed knee do not differ in their effects on graft healing, postoperative knee function, and patient satisfaction (Fig. 2). The article focuses on the OKC and CKC exercises involving knee flexion-extension. The review uses relevant biomechanical and clinical studies to assess the potential effects that these exercises may have on graft healing. These include studies evaluating the intersegmental kinematics/kinetics of the knee, ligament strains, and clinical outcome through prospective randomized clinical trials.

The hypothesis is that OKC and CKC exercises for the early rehabilitation of the ACL-reconstructed knee do not differ in their effects on graft healing, postoperative knee function, and patient satisfaction.

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