Although the effects of limb length discrepancies (LLDs) are far-reaching, the biomechanical management options for this condition are also vast. In light of this, the panelists explain their experiences with optimal LLD evaluation and what components of orthotics and lifts they utilize to treat this condition.
What do you think is the most effective and reliable approach to assess a limb length disparity (LLD) in your experience?
In his early practice, Joseph D’Amico, DPM used clinical and radiographic tests to determine the existence of LLD. The anterior and posterior iliac spine levels, pelvic brim obliquity, asymmetry of skin folds, asymmetry of calcaneal stance position and ranges of motion, anterior superior iliac spine (ASIS) or umbilicus to medial malleolus measurements, and standing radiographs were all measured and/or assessed.
“It comes with experience.” “I found that none of these methods tested function symmetry,” Dr. D’Amico says. “Because observational gait analysis has proven to be a poor indication of foot and limb function, I started using computer-assisted gait analysis to examine limb asymmetry.” 1,2
Dr. D’Amico considers a comparison of temporal parameters, plantar pressures, and center of force trajectories to be the most important and reliable markers. For these tests, he says he prefers computer-assisted gait analysis because other diagnostic approaches can’t evaluate the forces that occur beneath the foot and inside the shoe. According to Dr. D’Amico, the data from the computer-assisted gait study aids clinicians in making a more precise evaluation of whether the individual is working symmetrically.
Dr. D’Amico explains, “Like tires on a car, the idea is to have both wheels precisely aligned and spinning at the same pace for the same amount of time, generating the same pressure.”
According to Stanley Beekman, DPM, a more thorough examination is required than simply measuring limb lengths.
“The length of one leg compared to another is useless unless it’s compared to the rest of the body,” Dr. Beekman says.
For example, if a patient’s lengthy leg is compensated for by iliosacral joint posterior innominate dysfunction, there is no functional deficiency. Dr. Beekman suggests assessing the anterior superior iliac spines to the ground in neutral and relaxed positions, as well as the posterior superior iliac spines to the ground in neutral and relaxed positions, ankle dorsiflexion, and gait.
“I automatically put leg length disparity in my differential diagnosis if the patient has unilateral foot or leg complaints,” says R. Daryl Phillips, DPM.
Dr. Phillips, on the other hand, emphasizes the necessity of a complete history. He inquires about a history of back pain, muscle exhaustion, sacroiliac joint pain, and whether symptoms are worse when standing or walking in patients he suspects of having LLD. If the patient responds yes, podiatrists should look for a functional or anatomical leg length disparity, according to Dr. Phillips.
Due to the difficulties in properly identifying the required landmarks, Dr. Phillips no longer uses a tape measure to determine the length of the individual limb segments. Instead, he does a non-weightbearing assessment with the patient supine, then places the trunk and legs in such a way that a straight line might be drawn from the nose through the manubrium sternae to the symphysis pubis, as well as a point where the knees or malleoli touch.
“Then, with equal force on both legs, I check to see if the bottoms of the heels are at the same distal level or if one is more distal than the other,” Dr. Phillips explains. “While this isn’t an exact measurement, it does show a potential difference.”
Dr. Phillips next asks the patient to stand comfortably and examines the arch height, medial prominence of the navicular and medial malleolus, and/or calcaneal eversion for asymmetry. Asymmetry in popliteal space tension, which indicates whether one knee is more flexed than the other, is also something he looks for. Finally, he examines the pelvic brim height for equality. Dr. Phillips may conduct a radiographic leg length discrepancy study with the patient standing to identify the specific anatomical parameters if the physical exam reveals a leg length difference.
What variables do you consider while deciding whether or not to treat an LLD?
According to certain studies, over 90% of the population has some degree of limb asymmetry, says Dr. D’Amico, who adds that the average gap is less than half an inch (1.1 cm) and that most people can easily correct for it.
3-5 Recurrent asymmetric symptoms, especially those affecting the low back, may be a patient’s presenting worry in cases with a bigger LLD, according to Dr. D’Amico.
“That’s not to suggest that disparities of less than a half inch won’t result in asymmetrical forces and symptomatology,” Dr. D’Amico explains, “since, ideally, all mechanical models work more efficiently and use the least amount of energy when operating symmetrically.”
He goes on to state that even tiny differences of one-eighth inch might worsen, maintain, or trigger existing pathology, particularly in stressful settings like those found in repetitive motion sports like running. Overall, Dr. D’Amico believes that the pressures placed on the musculoskeletal system and its response will indicate whether or not pathology requires care.
“Because symmetrical function is the ideal state, asymmetrical function demands study, especially in active individuals,” Dr. D’Amico says.
Asymmetric symptoms and accompanying asymmetry, according to Dr. Beekman, are the most essential determining variables for therapy of an LLD.
“If a patient has cuboid syndrome, peroneal tendonitis, chronic ankle sprains, Achilles tendonitis, iliotibial band syndrome, or trochanteric bursitis, and I identify a structural or functional deficiency on that side, then addressing the asymmetry would be part of the treatment,” explains Dr. Beekman. “However, if an equinus develops as a result of a functionally short leg, compensation may develop that mimics pronatory long leg symptoms.”
Dr. Phillips believes that back pain made worse by standing or walking should be treated with podiatric therapy.
“I never tell patients that I can cure their back pain; instead, I tell them that I might be able to help,” explains Dr. Phillips.
He goes on to argue that determining the problem’s fundamental cause is critical before deciding how or whether to cure it. However, if symptoms are present, Dr. Phillips advises that treatment is usually required. If an adult patient has no symptoms in his back, legs, or feet, he usually does not seek therapy, but Dr. Phillips believes this is an unusual occurrence.
What is your rationale and methodology for dealing with LLD? How would you use this logic to prescribe and make orthotics for these patients?
According to Dr. D’Amico, his primary goal is to realign the osseous and soft tissue components of the foot and ankle by combining the prescription of bespoke foot orthoses with stretching of tight musculature and strengthening of weak musculature. This is especially true in cases of functional disparity, which is resolved once realignment and improved function are achieved.
When Dr. D’Amico notices asymmetry, he starts in-shoe lift therapy by adding a quarter-inch felt heel lift to the shorter limb and retesting the patient. If symmetry is not achieved, he adds another eighth inch before retesting, up to a five-eighths inch lift or a one-half inch heel lift with a one-eighth inch complete foot insole. Dr. D’Amico evaluates the patient three months after obtaining symmetry. He claims that most of the time, the lift may be removed or reduced in size.
“Lifts aren’t everlasting,” says Dr. D’Amico, “since the body tends to integrate the mechanics the lift induces and strives to recreate the effect on its own whenever possible.”
Dr. Beekman highlights the need of determining treatment based on the patient’s history and gait evaluation, including when to refer to an osteopath, chiropractor, or physical therapist. If none of the aforementioned specialists are accessible, a lift on the side with the low posterior superior iliac spine may be considered. However, if the asymmetry is caused by a spinal constraint (as seen by an asymmetry of the level of the head during locomotion), the lift will aggravate the problem, according to Dr. Beekman. According to Dr. Beekman, if the patient’s complaints have a pronatory component, the lift can be included in the orthoses.
Dr. Beekman prescribes orthoses if both the anterior and posterior superior iliac spines are level and become unlevel when the patient is in the relaxed calcaneal stance position. When dispensing the devices, he ensures that the patient’s pelvis is level (or at least improved) when standing on them.
Dr. Beekman continues, “If the anterior and posterior superior iliac spines are high on the same side with the patient in neutral calcaneal stance, there is a structural leg length problem that a lift may address.” According to Dr. Beekman, pronation is a compensation if the two iliac spines are leveled by a relaxed calcaneal stance. Orthoses without a proper lift, according to Dr. Beekman, will result in proximal pathology in this case.
Dr. Beekman states the patient has primary iliosacral dysfunction if the anterior and posterior superior iliac spines are elevated on opposing sides. A lateral talus subluxation is indicated by discomfort of the sinus tarsi on the side of the low posterior superior iliac spine.
Dr. Beekman explains, “There is an acupuncture point called GB 40.” “I use a sinus tarsi injection and twist the needle twice around to address this.” This frequently corrects that side’s posterior innominate.”
He acknowledges that musculotendinous balance exercises or referral to an osteopath, chiropractor, or physical therapist may be beneficial.
Dr. Beekman utilizes heel and sole lifts that aren’t high enough to produce a secondary spinal curve or pelvic transverse rotation. He claims that a heel lift within the shoe could be anywhere from a quarter to a half inch. If this does not relieve symptoms, Dr. Beekman recommends having a shoemaker add a heel lift to the exterior of the shoes and a sole lift that is inversely proportional to the amount of equinus the patient has.
The standing radiological study, according to Dr. Phillips, can disclose the exact length of the legs as well as a lot about function. He points out that a functional leg length discrepancy can be caused by asymmetries in coronal plane hip and leg angles. If the LLD is only functional, he solely treats the function. Dr. Phillips may, however, give additional lift under the short side if it is anatomically correct.
When the small leg has less ankle joint dorsiflexion than the long leg, he uses a heel lift. If both sides of the ankle joint have equal dorsiflexion, Dr. Phillips may utilize a lift that runs the length of the shoe.
“It’s always a matter of whether I should utilize the lift on the inside or outside of the shoe,” Dr. Phillips adds. “One-quarter to one-half inch of heel lift can normally be accommodated in the shoe, depending on the shoe depth. More than a half-inch usually indicates that the shoe has to be altered.”
Dr. Phillips says that if the difference is less than a half inch and there is little pronation in either foot, he may just use a lift on the short side. When patients compensate for LLD by pronating the foot on the long leg more than the short leg, he finds that the excess pronation on the long side does not frequently autocorrect when raising the short leg.
“The majority of these people necessitate extra orthotic therapy,” Dr. Phillips says. “Most of the time, I’ll just add the lift to the orthotic,” says the doctor, “so the patient doesn’t have to put lifts in all of his shoes.”
Dr. Beekman previously worked at the Ohio College of Podiatric Medicine as an Assistant Professor of Podopediatrics and Sports Medicine (now the Kent State University College of Podiatric Medicine). In both podiatric orthopedics and podiatric surgery, he was board-certified. Dr. Beekman is no longer practicing medicine.
Dr. Phillips is the Director of the Residency in Podiatric Medicine and Surgery at the Orlando Veterans Affairs Medical Center in Orlando, Florida. He holds American Board of Foot & Ankle Surgery and American Board of Podiatric Medicine diplomas. Dr. Phillips is a clinical volunteer Professor of Podiatric Medicine at the University of Central Florida’s College of Medicine. He’s a member of the American Society of Biomechanics, as well.
Dr. D’Amico is a Professor and Past Chairman of the New York College of Podiatric Medicine’s Division of Orthopedics. He is a Fellow of the American College of Foot and Ankle Orthopedics and a Fellow of the American Academy of Podiatric Sports Medicine. He is a Diplomate of the American Board of Podiatric Medicine, a Fellow of the American College of Foot and Ankle Orthopedics, and a Fellow of the American College of Foot and Ankle Orthopedics. Dr. D’Amico is a New York City-based private practitioner.
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2. Cavanaugh, P. Running’s shoe-ground interface. Symposium on the Foot and Leg in Running Sports, edited by R.P. Mack. Mosby, St. Louis,1982:30-44.
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Keys to Recognizing and Treating Limb Length Disparity, D’Amico JC. Podiatry Today, vol. 27, no. 5, pp. 66-75, 2014.
Limb length discrepancy: diagnosis, clinical importance, and management, Blustien SM, D’Amico JC. 1985;75(4):200-206 in J Am Podiatr Med Assoc.