Differences in leg length are fairly common, in a previous post I wrote about how leg length differences can lead to a breakdown in the soft tissues of the knee joint, mostly on the longer leg side of the body. There are other considerations and symptoms associated with leg length.
I routinely do postural screens for all clients. Postural asymmetry is a significant finding, determining why there is asymmetry is the challenging part.
My first concern is always to rule in/out spinal conditions and pelvis injuries that lead to muscle spasming and/or weakness. These injuries can distort body alignment.
Next I want to rule in/out structural/anatomical issues. Some people are born with variations in their bone length mostly in the legs but also the pelvis. Interestingly, this past winter I purchased a pair of boots, the sales person told me they measure everyone’s feet and routinely see a smaller right foot!? This is another blog post.
There are several assessments I do to determine if the femur, tibia or ilium (pelvic bone) is of unequal length. My assessment process does not diagnose. An orthopedic evaluation and x-ray is the best way to determine structural asymmetry. In Part 2 I’ll go into more detail about what I do if I suspect leg length differences.
The last issue I look for is muscular weakness and/or tightness and how muscle function can impact posture. I test joint range of motion and manual strength tests as well as dynamic movement tests like squats, lunges, balance, jumping etc.
Why is assessing leg length important?
The body is subject to similar forces that a bridge, car or building experience. Forces like gravity (compression), vibration, rotation and shear act upon these structures testing the loading capacity of the materials. Ideally these forces do not exceed the tolerance of the structures. The alignment of the structures is also important: jumping up and down (running) places linear, rotational and shear forces on the spine, pelvis, femur, tibia, ankle etc. If the forces of running exceed the tissue tolerance (excessive training/poor repair) or if the alignment of the skeletal structures is not within “tolerance” excessive wear occurs at specific joints and soft tissues.
Leg length inequality always results in asymmetrical loading and body alignment. For a runner the gait pattern is not smooth: typically the body sways side/side, one arm may swing wider to aid balance and the pelvis dips to the shorter leg side. Often the longer leg hip has discomfort and stiffness – the hip flexors work hard to “brake” the forward fall from longer to shorter leg. One leg is often significantly stronger, this varies depending on the person.
Cyclists with leg length differences can suffer from a variety of issues, typically back and knee dysfunction. Since a bike is a fixed ergonomic device the pelvis/body will shift side/side when pedaling, the low back experiences excessive lateral movement. Often quadricep muscle force production is significantly different, the longer leg often does more work. Careful bike fit which includes alteration of pedal cleats and saddle are essential.
Curiously the fascia from hip to shoulder on the long leg side may be stiffer. Clients often complain about feeling “tight” along their rib cage and up into the arm pit. The longer leg “pushes” the body to the opposite side, the latissimus dorsi, abdominal obliques and quadratus lumborum are chronically contracted in order to maintain erect posture.
Asymmetrical muscle tightness continues up to the shoulder, neck and head as well. The head will tilt to the longer leg side as the neck muscles are over active maintaining the head/eyes in a neutral position. It is not uncommon to see cranial bone distortion – the eyes are displaced due to the constant tilting to maintain visual and vestibular equilibrium.
These are some of the issues with leg length differences, in part 2 I’ll continue with how I assess leg length as well as discuss pelvic asymmetry.