X-Rays Bone Length Studies
Also known as
leg length X-ray
A bone length study is an imaging exam for evaluating and calculating limb-length discrepancies. This study utilizes a long ruler placed on the film and three radiographs of the hips, knees, and ankles.
A bone length study is used to determine an inequality in the length of the limbs. This radiograph is ordered equally in adults as well as children who complain of spine and back pain. This procedure is used to diagnose limb length discrepancy, which is a condition in which the limbs have a noticeable and unequal length, which proves to be a cosmetic and functional concern. The difference in leg length is commonly associated with compensatory gait irregularities, leading to arthritis in the entire lower body. Patients may also have other physical deformities and soft-tissue contractures, which may affect their leg functionality. Limb length discrepancy can also cause effects on the spine, such as lower back pain, bone degeneration, and arthritis. It has also been seen to cause incidences of scoliosis.
Your doctor may order a bone length study if they suspect you have limb length discrepancy (LLD). Although no one's limbs are precisely symmetrical, some may have significant differences in leg length. Although some patients do not show symptoms, others have symptoms such as:
- Knee or hip pain on one or both sides
- Back pain
- Limping
- Getting tired from walking too quickly
There is no preparation needed for a bone-length study. You may be requested to put on a hospital gown since clothing, especially those with clasps or buttons, can interfere with the X-ray. Other metal objects like jewelry, eyeglasses, and other accessories also need to be removed as they can interfere with the X-ray image. If your child is getting X-rayed, you must explain to them in as much detail as needed for their age what the procedure entails. It would also help to explain that staying still is crucial for the X-ray.
There are three different ways a bone length study will be performed on you. Your doctor will request either of the views which will follow these procedures: Orthoroentgenogram: Three images will be taken of the hip, knee, and ankle joints. You will be asked to lie still with one large X-ray cassette under you. Scanogram: Three images will be taken of your hip, knee, and ankle joint. You will be asked to lie on your back next to a calibrated ruler for this procedure. There is no radiographic cassette. Teleroentgenogram: This consists of a single radiograph of both lower limbs and thus causes less radiation exposure. In this, a single long cassette is placed behind the patient, and the X-ray is taken with you standing.
The X-rays will show the extent of the inequalities in your limb lengths. Discrepancies of 0.5 to 2.9 cm are considered healthy and regular. However, an imbalance of more than 2.5cm has traditionally been considered significant, with an increased likelihood of knee, hip, and lumbar spine pain. Based on your results, your doctor will recommend treatments if you have a significant limb length discrepancy. For substantial disparities, the doctor may recommend fitting a prosthetic. Other treatment plans include slowing the longer limb's growth rate in a process called epiphysiodesis or lengthening/shortening surgeries.
