Investigating the muscle imbalance in lower extremity with genu recurvatum

Genu recurvatum is defined by hyperextension of the knee in the stance phase. GR is a knee malalignment that causes the knee to bend backwards. Multiple factors can cause GR, including weakness of the muscles around the knee joint, excessive plantar flexion, a proprioceptive disorder, spasticity of the quadriceps and neurological or musculoskeletal injury. GR is observed in 40% to 68% of stroke patients. Thus the purpose of this study is to assess GR on healthy people in relation to muscle activity in lower extremity, knee joint position sense and knee stability in order to prevent GR. 33 participants 9F/22M, mean age of 22.8 ±2.6SD were included in this study after signing a consent form. The degree of GR was measured with a goniometer, knee joint position test was used to assess the proprioception and sEMG was used to assess the activity of four major muscle; biceps femoris, anterior tibialis, rectus femoris, and gastrocnemius. 21 participants were found with GR and 12 participants without GR. The participants were divided into two groups according to the GR test. There was a significant difference in terms of GR degree between the two groups. Data showed when there's more than 10° the muscle activity ratio shifts to favor rectus femoris with 64.3%. Consequently, when there's less than 10° the muscle activity ratio shifts to biceps femoris with 51.8%. Additionally, the muscle activity ratio remained the same percentage for the anterior tibialis and gastrocnemius when we compared the two groups. Therefore, we concluded that having weaker activity in the posterior muscles of the thigh, specifically the biceps femoris could be a factor in developing GR. Thus, assessing the biceps femoris muscle activity is a valid assessment to indicate people at risk of developing GR.