Hamstring shortening in healthy adults.

Hamstring shortening (HS) causes changes in the posture and walking ability in spastic children, however, there are no studies defining the abnormalities in patellar alignment in individuals with HS.Twenty-five patients with a primary complaint of anterior knee pain, having HS detected at physical examination, and 11 healthy individuals without any HS or knee discomfort as a control group are included in this study. Serial x-rays of the spine, pelvis and knee are taken and knee x-rays are evaluated for the position of the patella in both groups.In patients with Knee Extension Deficit (KED) ≥ 60°, the Blackburne-Peel ratio is lower and the Insall-Salvati ratio is higher than the other groups, denoting a cephalic location of the patella (p < 0.05). There are no changes in the congruency and sulcus angles between the HS and control groups. Vertebral and pelvic changes correlate well with the literature, confirming that significant alterations occur after 60° of KED in adults.The extensor mechanism of the knee is affected and patella is located higher than normal in patients with severe HS, which may be a cause for knee discomfort. In the light of these findings, a routine knee extension deficit examination can be suggested in the initial evaluation of knee discomfort.