Houston Methodist. Leading Medicine

Knee News

Knee Muscles in Sync

Knee pain is well known to many athletes. It is also a common complaint in the general population. Pain with stair climbing, sitting too long, squatting, and kneeling is a sign of patellofemoral pain syndrome (PFPS). This problem occurs when the kneecap (patella) doesn't slide up and down properly as the knee is straightened and bent.

The thigh muscle, called the quadriceps, moves the patella. This muscle is divided into four parts. Two of these, the vastus medialis obliquus and vastus lateralis, are the focus of many studies. The vastus medialis obliquus (VMO) is the section of muscle on the inside of the front of the thigh. The vastus lateralis (VL) is along the outer front thigh.

For many years, it was assumed that strengthening the VMO portion of the muscle would help PFPS. Yet some research showed this wasn't true. Since then, many researchers have been studying the VMO in relation to knee problems. They are trying to find out when and how this muscle works. This may offer some help in finding better ways to treat knee pain from PFPS.

A new study from Australia shows that this muscle contracts differently depending on the movement. For example, when rising up on toes, people without problems from PFPS contract both the VMO and the VL at the same time. However, in people with PFPS, the VL contracts first--before the VMO. It was also noticed that when rising up on toes, there was a difference in how the calf muscle contracts. In people with PFPS, this muscle contracts later than for those without PFPS.

Timing of muscle contractions may depend on the task. Finding out how and when muscles around the knee and ankle work may help in the treatment of PFPS. Comparing muscle function in people with PFPS to those without PFPS is the current focus of new and helpful research.

Sallie M. Cowan, BAppSci, et al. Altered Vastii Recruitment When People With Patellofemoral Pain Syndrome Complete a Postural Task. In Archives of Physical Medicine and Rehabilitation. July 2002. Vol. 82. No. 7. Pp. 989-995.


*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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