Hamstring Length and the Patellofemoral Joint

This past week my most recent review was posted on Research Review Service, a site specifically for health care professionals of manual and rehabilitative therapy. The Influence of Reduced Hamstring Length on Patellofemoral Joint Stress During Squatting in Healthy Male Adults by Whyte et al was published earlier this year in Gait Posture.

Here's a brief summary of the study:

Study Purpose:

• To determine the presence of a relationship between hamstring length and PFJ stress at 3 specific knee joint angles of flexion.

Study Population:

• 16 recreationally active males divided into two groups based on knee joint angle-measured hamstring length.

Methodology:

• A biomechanical model incorporating knee joint angle, knee extensor moment, and PFJ contact area was used to quantify PFJ stress.
• MRI and 3D motion analyses were also utilized in this study.
• A one-way ANOVA to determine the variations in PFJ stress between the 2 groups (with and without reduced hamstring length) was used.

Main Findings:

• Patellofemoral Joint stresses differed significantly between the two groups at specific angles of knee flexion.
• No significant differences in hip angles between the two groups.

Clinical Application:

• This study demonstrated that subjects with reduced hamstring lengths have increased PFJ stress during various positions of the squatting movement.  As a result, such a decrease in length MAY contribute to the pathogenesis of various conditions relating to the knee.
• These results enable us to consider another factor when managing those with knee pathology.

For a complete and "evidence-informed" understanding of the study, check out my review. I have obviously left out specifics from this study in this post as Research Review Service is a paid membership site. However, if you would like more information, please do not hesitate to ask.