Hamstring shortening in healthy adults

Area of Science:

• Orthopedics
• Pediatric Medicine
• Biomechanical Engineering

Background:

• Hamstring shortening (HS) is known to affect posture and gait in spastic children.
• Previous research has not defined patellar alignment abnormalities associated with HS.
• Anterior knee pain is a common complaint in individuals with HS.

Purpose of the Study:

• To investigate patellar alignment in individuals with hamstring shortening.
• To determine if severe hamstring shortening correlates with specific patellar position changes.
• To explore the relationship between knee extension deficit and patellar alignment.

Main Methods:

• A case-control study involving 25 patients with HS and 20 healthy controls.
• Serial X-rays of the spine, pelvis, and knee were obtained for all participants.
• Knee X-rays were analyzed for patellar position using the Blackburne-Peel and Insall-Salvati ratios.

Main Results:

• Patients with a Knee Extension Deficit (KED) ≥ 60° exhibited lower Blackburne-Peel and higher Insall-Salvati ratios, indicating a cephalic patellar location (p < 0.05).
• No significant differences in patellar congruency or sulcus angles were found between groups.
• Vertebral and pelvic changes in patients with severe KED align with existing literature.

Conclusions:

• Severe hamstring shortening affects the knee's extensor mechanism, resulting in a higher-than-normal patellar position.
• This altered patellar location may contribute to anterior knee pain in individuals with severe HS.
• Routine knee extension deficit assessment is suggested for initial evaluation of knee discomfort.