The Effect of Kinematic Chain Manipulative Therapy on the Frontal Plane Knee Movement in Cycling

Purpose: The aim of this study was to evaluate the effect of kinematic chain manipulative therapy on the frontal plane knee movement in cycling. Methods: in this study 13 amateur cyclists aged between 25 and 65 years old participated and underwent kinematic chain manipulative therapy executed by a professional orthopaedic manual therapist. Before and after the intervention the frontal plane knee movement was measured in a cycling trail using a 3D motion analyse system. Results: Eight out of thirteen subjects (62%) showed a decreasedand three subjects showed an increased frontal plane knee movement. The mean difference before and after manipulative therapy was a decrease of 2 mm ± 2,6 (mean ± SD). A t-test revealed a statistically significant difference between the frontal plane movement beforeand after kinematic chain manipulative therapy (P=0,041). Conclusion: The study shows a decreased trend in frontal plane knee movement in cyclists but further research with a bigger research group will be needed before drawing any firm conclusions. Because of the good quality of cycling paths and great performance of Dutch professional cyclists, the population of active cyclists in 2014 in the Netherlands has been increased to 815.000 (1). Cycling may be a low-impact sport but it is also very repetitive: a cyclist may average up to 5000 pedal revolutions per hour (2,3). Therefore, the smallest change whether anatomic or equipment related can lead to dysfunction, decreased performance, pain and chronic or overuse injuries (2,3). The knee is, with 50%, the most common site of overuse in cyclists (4,5). Knee pain is frequently caused by patellofemoral pain syndrome (PFPS) or “cyclist’s knee” and iliotibial band (ITB) friction syndrome (2,6–9). Most of the time an overuse knee injury find its origin in a change of intrinsic or extrinsic factors like incorrect bike fit, increase in training distance or intensity, pushing big gears or training in hills or windy conditions (3,5). The repetitive flexion and extension of the knee during cycling and the force generated by the quadriceps muscle contraction is translated to the patellofemoral joint which results in injury of the patella or the iliotibial band (3,6). Because of the normal valgus angulation of the distal femoral condyles relative to the femoral shaft, the knee does not move straight up and down in the frontal plane but moves in a clockwise circular motion. When pushing down on the pedal the knee extends and adducts and when the pedal returns to the top the knee flexes and abducts (2,10) as shown in Figure 1. The frontal plane knee angles in healthy cyclists range from 2 to 4 degrees of abduction to 1 to 6 degrees of adduction (10,11). This mediolateral frontal plane knee movement during the downward pedal stroke in cycling seems to play an important role in the development of overuse injuries like PFP and ITB syndrome (3,11–15). Cyclists with knee injuries show an abnormal frontal plane knee movement pattern during the down stroke (10). This abnormal pattern generates too much pressure on the patellofemoral joint or creates an impingement angle at the bottom of the down stroke which can cause pain. Research has shown that after a ‘normalization’ of the frontal plane knee movement by using a special pedal for the foot whereby the cyclists show a linear path when viewed in the frontal plane, the symptoms of cyclist with knee pain decreased (1). An important and effective way to reduce the frontal plane knee movement and the strain on the lateral side of the knee through varus load, Figure 1 Frontal plane knee movement