True and functional shortening
With true shortening, the bone itself is shorter - the femur, the tibia, or both, and the difference can be seen on x-rays. In the functional case, the length of the bones is the same, but the leg appears and behaves as shorter: the cause is a pelvic distortion due to muscle imbalance, limited movement in the hip or knee joint, severe scoliosis, different heights of the arches of the feet, or one foot falling inward. It is fundamentally important to distinguish between these options: adding an insole during functional shortening can perpetuate the problem instead of solving it.
- True - different bone lengths
- Functional - pelvic distortion and contractures
- Combined options
- A difference of up to 1–2 cm is usually asymptomatic
- A difference of 2 cm is considered significant
Reasons
In children, the most common cause of true shortening is damage to the growth plate due to a fracture: the bone stops growing at full strength, and the difference increases with age. Less common are congenital underdevelopment of the hip or tibia, consequences of osteomyelitis and inflammation of the joint, and neurological diseases with unilateral damage. Sometimes, on the contrary, after a fracture the bone grows faster and becomes longer. In adults, the difference appears after displaced fractures, joint replacement, as well as with severe unilateral arthrosis, when the joint seems to sag.
- Damage to the growth plate due to fracture
- Congenital underdevelopment of the thigh or lower leg
- Previous osteomyelitis and arthritis
- Neurological diseases
- Displaced fractures in adults
- Consequences of endoprosthetics
- Unilateral severe arthrosis
How does this manifest itself?
A small difference is usually not noticeable. With a difference of more than two centimeters, a person begins to limp, step on the toe of the shorter leg, the pelvis warps, and the spine bends compensatoryly. Pain and fatigue appear in the lower back, pain in the knees and hip joint on the longer leg, and uneven wear of shoes. In children, asymmetry of the gluteal folds, different heights of the knees in a lying position, and tilt of the shoulders are noticeable. Long-term misalignment can lead to permanent changes in the spine and early arthrosis.
- Lameness and toe walking
- Pelvic tilt and shoulder tilt
- Lower back and knee pain
- Fatigue when walking
- Uneven wear on shoe soles
- Asymmetry of folds in a child
How to measure correctly
Clinically, the difference is determined in a standing position: planks of a known thickness are placed under the shorter leg until the pelvis becomes symmetrical; This way you can immediately see what kind of compensation is needed. Measuring with a measuring tape while lying down is less accurate. The objective method is radiography of the pelvis and lower extremities in a standing position with measurement of bone length, and, if necessary, special computed tomography protocols. In a growing child, bone age is additionally assessed to predict what the difference will be at the end of growth.
- Measuring while standing with planks placed
- Assessing the symmetry of the pelvis and shoulders
- X-ray of the pelvis and legs in a standing position
- Spine assessment for scoliosis
- Bone age in children for prognosis
- Checking the mobility of joints and feet
Treatment
With functional shortening, they work with the cause: they stretch shortened muscles, strengthen weak ones, restore joint mobility, and correct the position of the foot with an insole. With a true difference of up to two centimeters, a heel pad or insole is usually enough, and with a larger difference, compensation in the shoes, and not the whole difference is raised at once, but part of it so that the body adapts. In a growing child with a predicted large difference, surgery may be possible to slow the growth of the longer leg. In case of significant shortening, limb lengthening techniques are used.
- Therapeutic exercise for functional shortening
- Restoring joint mobility
- Heel pad or insole with a difference of up to 2 cm
- Compensation in shoes for larger differences
- Gradual increase in compensation height
- Managing growth plates in children
- Limb lengthening with significant shortening
- Observation by an orthopedist until the end of growth