‘I have to lift my leg into the car”. This is pretty common and we see it most weeks.
Ben Tolson, one of our acupuncturists and a Sports and Deep Tissue Massage therapists was tackling one of these recently. We’ve had a good discussion about it over coffee in the clinic. Hence this blog.
We came to the conclusion that the classic and often misdiagnosed problem here is low-grade mechanical back pain as a result of a twisted pelvis.
Why should this hurt and so stop you lifting your leg? Well, the answer here is in your anatomy. The main muscle that you use to lift your leg is the iliopsoas muscle. This muscle originates along the edges of all the vertebrae in your lumbar spine and inserts on the top of your femur. You use it to bend at the hip and so lift your leg into the car. The muscle has to contract in order to pull the femur bone closer to the body but hinged at the hip. An unfortunate side effect of this is that it also causes all the vertebral bodies in the lumbar spine to be compressed. This compression will hurt your low-back.
The world guru on this is a bloke called Professor Stuart McGill. He writes in his book that the compression caused by carrying out the traditional sit-up “..imposes approximately 3300 N (730 lbs) of compression on the spine”. He adds that a bent leg raise – so, the action you do to get into your car, imposes 1767 N of compression. If your low-back is irritated, then this compression will cause your low-back joints to howl. Your brain will then prevent you from even carrying out the move. You will not want to lift your leg in and out of the car. What you are doing to prevent this compression is not using this muscle but lifting your leg in and out by hand. You will have to lift your leg into the car.
Prof McGill adds that the National Institute of Occupational Safety and Health set the limit for low-back compression in workers at 3300 N. So, it certainly makes sense to never do a sit-up again. And now you know why your low-back hurts. You also know why you have to lift it in and out of the car (and I bet it is pain free when you do this as your iliopsoas muscle is not being used at all).
However, there are a few other nasty reasons you can’t lift your leg. However, these are very rare and pretty easy to diagnose once you know what you are thinking about. They are:
- You can injure the iliopsoas muscle and cause it to calcify right at the muscle to tendon junction and as it passes over the pelvic rim this will sting.
- A tear in the cartilaginous edge of the hip – a labral tear but this should be pretty obvious if checked correctly.
- You can have a Sartorius muscle injury or a groin strain, and, again, this should be pretty easy to diagnose if you think about it first.
- Arthritic changes can also cause the same problem but you should know about these.