Detect, Correct, and Prevent Conditions Caused by Leg Length Discrepancies
By: John Palo, BS, DC, CCSP, DABCO
“Doctors, teachers, and those who nurse the sick should be aware what sort of thing is man, what is life, what is health, and in what manner a parity and concordance of the elements maintains it; while a discordance of these elements ruins and destroys it; and one with a good knowledge of the nature of things mentioned above will be better also to repair it than one who lacks knowledge of them…”
— Leonardo da Vinci
In a study of metatarsal stress fractures, it was found that they most frequently occurred in the foot of the longer leg (70% were found on the longer leg, while only 10% were found on the shorter leg; 20% were found equally on legs of equal height).1 Other studies have found degenerative changes of the hip2 and lumbar spine3 occur much more frequently in the longer lower limb. As a profession, Chiropractic is in the best position to detect, correct, and prevent these widespread joint degenerations caused by a longer lower extremity.
How to Detect a Leg Length Discrepancy
There are many ways to determine a leg length discrepancy. Perhaps the most accurate is an erect A-P view of the lumbar-pelvic area (both knees should be fully extended, with equal body weight at both feet). The X-ray view will present, on the longer-leg side, an elevated femoral head, a raising of the iliac crest and sacral table on that side, as well as a lumbar-sacral scoliosis on the shorter leg side. The X-ray view will also alert us to any pathology, especially osteoarthritis that may present at the longer leg femur-iliac joint.
Probably the least accurate measurement for leg length discrepancy is a visual assessment at the internal malleoli of the prone or supine patient. Any contraction at one or the other loin will raise a lower extremity and give a false reading.
The following are some fairly accurate ways to determine a leg length discrepancy. Please note that the greater the length discrepancy, the more supportive these tests will prove. Minor discrepancies may find some of these tests wanting.
1. Measurements with an inclinometer resting upon the superior crests of the ilia
of a standing patient are fairly accurate. Watch for the tendency of the patient to
flex the longer-leg knee. This will throw your reading off. (Placing a heel lift
under the heel of the shorter leg and remeasuring for levelment can give us an
estimate of the amount of discrepancy present.)
2. Foot hyperpronation with characteristic outward flaring of the calcaneus will
cause a leg shortening.
3. A carpenter’s level or inclinometer placed atop of the knees (patient sitting)
can reveal a dislevelment due to foot hyperpronation shortening or an actual tibia
bone-length discrepancy. In cases of a lower leg discrepancy, a patient, asked
to cross his/her legs, will place the longer leg over the shorter one.
4. A measurement at the internal malleoli, made with both knees bent at 90˚ (patient prone), can reveal a tibia bone length discrepancy.
5. The gluteal cleavage will be higher on the longer-leg side.
6. There will be a deeper and longer loin cleavage on the longer-leg side.
7. There will be greater lateral protrusion of the greater trochanter on the longer-
8. The shoulder will usually be lower on the longer-leg side. This will cause the
hand to be lower on the longer-leg side.
9. A leg length discrepancy can be determined by measuring the distance
between the anterior superior iliac spine and the internal malleolus on each side
10. Elderly patients who climb stairs one step at a time will do it with the shorter
leg. Conversely, they will descend stairs, one step at a time, leading with the
longer leg. This stepping down with the longer leg is less taxing. It can spare a
patient longer-leg knee/hip and lower back pain that may be produced by
stepping down with the shorter leg. Stepping down with the shorter leg forces
the longer leg to bend more deeply with full body weight upon it; it also involves
greater pelvic distortion as the body strives to maintain a level sacral table.
11. People whose work involves periods of long standing will keep their longer
leg bent, or forward, or abducted. This helps keep their sacral table level by
lowering the higher sacral table side caused by the longer leg. This spares the
onset of low back pain. The shorter leg usually acts as the pivotal leg. Standing
at rest, with the preponderance of our body weight upon the shorter leg, we tend
to sally forth with the longer leg.
12. People whose work involves long periods of standing will be found to place
their longer leg upon an elevation, such as a stool. This helps lower the sacral
table on the longer leg side. It also keeps the sacral table level from front to
back. We should be mindful that the body seeks to maintain a level sacral table
with a slight back-to-front incline as well as a horizontal gaze. It will contort itself
any which way to achieve these most efficient levelments.
13. Shoes will show grater heel wear on the longer-leg side. This may be the
body’s attempt to equalize leg lengths and level the sacral table.
14. Comparative measurements made between the floor and the bottom of the
navicular bone can assess the leg shortening due to pronation inequities.
15. A poke at the popliteal space behind the knee of the longer leg will elicit
flexion of the knee more readily than one at the shorter leg. This is probably due
to the tendency of the longer-leg knee to flex in order to level the sacral table.
The Longer Leg Greater Workload
More degenerative changes occurring at the longer-leg side is probably due to that leg’s carrying the greater work load. This adversely affects the longer-leg foot, knee, and hip. Also, by raising the sacral table on that side, the longer leg creates a lumbar spine scoliosis handicap at the shorter-leg side.
Walking. In walking, the foot of the longer leg makes heel-ground contact with a somewhat flexed knee and hip. This is an attempt of the body to shorten that leg to the length of the shorter leg. This helps keep a level sacral table. It also keeps us walking straight ahead. If the longer leg did not so bend, we’d be walking around in circles in direction of the shorter leg. The longer leg’s knee and hip flexing is an attempt by it to compensate for the shorter stride of the shorter leg. However, there is a degeneration price to pay for this somewhat strenuous adaptive process. (This price is compounded in the running patient.) It is these adaptive forces, at the longer-leg side, that appear to be the causes of the onset of greater knee, hip, and lumbar vertebral degenerative changes.
Stair climbing. Also note, in stair climbing, the longer leg’s knee rises higher (due to a longer lower-leg length), necessitating greater knee and hip flexion to be able to place the foot on the next step. This adds to the leg extension distance and force needed to then raise the body to the next step. This is why we see the elderly climb stairs one step at a time, using the shorter leg as the climber. Shorter leg length climbing involves less weighted knee and hip flexions and, more importantly, less knee and hip extension needed to raise the body to the next step. Thus, in climbing stairs, the shorter leg joints are taxed less than those of the longer leg.
Not only would use of the longer leg be more difficult because of its length. Especially in the elderly, the years may already have taken their toll. There may already be present some degenerative pathology in the longer-leg joint complex. So its use may already be painful in stair climbing. Again, climbing with the longer leg involves greater weighted knee and hip flexion and extension movement over a greater arc than climbing with the shorter leg.
Also note, these elderly “one-step-at-a-time” stair climbers will step down with the longer leg. Stepping down with the shorter leg would force greater weighted flexion at the knee, hip, and pelvis at the planted lower-leg side. On the other hand, stepping down with the longer leg assures reaching the step surface below with less involvement of any knee, hip flexion, and pelvic distortion at the shorter leg.
Correcting a Leg Length Discrepancy
Too many Chiropractors give the reclining patient a pull upon the shorter leg and then claim they have just fixed the discrepancy. All they’ve probably done is temporarily stretched the loin muscles at the shorter leg side. This is not attending to the real problem. Barring a posterior rotation of the ilium upon the sacrum that may account for some leg shortening, the leg-pulling “cure” is deceptive. However, an adjustment at the posterior iliac spine may prove salutary.
Here’s how to correct leg-length discrepancies:
Hyperpronation. Pronation cushions the weighted foot. However, as Austin points out, “The most common underlying cause of a functional leg-length inequality is asymmetrical bilateral pronation.”4 The foot that pronates most causes the most leg length shortening. Bilateral orthotics aim at equalizing the pronation of the feet to eliminate the greater pronation leg-shortening factor. If there is no actual bone shortening present, such orthotics should serve to correct the leg length imbalance and level the sacral table.
Bone length deficiency. The tibia and/or the femur may be shorter on one side. In these cases a heel lift should be added to the shorter-leg orthotic. A pair of arch supports may be used during the examination, to ascertain their effect upon leg length. If the leg length measurements, with arch supports, still show a discrepancy, we are probably dealing more with a bone length deficiency. A heel lift to make up for that osseous deficiency should be added to the orthotic of the shorter leg.
Asymmetrical bilateral pronation and bone length deficiency appear to be two more prevalent causes of leg length discrepancies. The use of corrective orthotics will help prevent the onslaught of degenerative changes, upon the longer-leg side, to the knee, hip, and low back. Orthotics will force the now-lengthened shorter leg to assume more of the burden of ambulation. In cases of severe osteoarthritis of the longer-leg hip joint, a gradual orthotic/heel lift lengthening of the shorter leg, in excess of the naturally longer leg, may be tried. This office has found a modicum of relief in this reversal of leg lengths.
Knock-knee and bow-leg. More rarely, a unilateral knock-knee or a bow-leg may present a shorter leg. In either case a heel lift should be considered. As a knock-knee may incite degenerative changes at the lateral femur-tibia joint and the lateral patella-femoral joint, wedging (thickness medial) at the inner aspect of the heel of the orthotic should be considered. This tends to reduce the amount of knock-knee and force more body weight upon the healthier knee joints.
In a unilateral bow-leg the reverse obtains. The thickness of the heel wedge is placed at the lateral heel part of the orthotic. This tends to correct part of the bow-leg. And, it may relieve any medial femur-tibia and medial patella-femoral joint pain that may be present. The wedge will force more of the body weight to the healthier lateral joints of that knee.
Knock-kneed patients should use inner heel wedges. Bow-legged patients should use outer heel wedges. Wedges, in these cases, may help deter the age-related onslaught of knee pains from early degenerative patella-femoral syndrome and unilateral femur-tibia osteoarthritis. In prescribing orthotics these are some of the things to consider. When possible, all corrections of the conditions found at our examination should be incorporated into the orthotics.
Predictions are that more and more of us will be getting older and older. This means degenerative changes from leg-length discrepancies will become more numerous and inflict a greater and greater amount of pain on us for a longer and longer time. The Chiropractic profession can spare millions from such misery in our final years by early detection, prevention, and correction.
From what we have learned about the effects of a leg length discrepancy upon feet, knees, hips, low back, and up the body structure, the Chiropractic profession should come more to the fore for early screening for leg length discrepancies. This may be one of our greatest services to the good health of humanity. Already there are too many patients with degenerative changes that are too far advanced and may need surgery. We did not catch them in time. The earlier we catch leg length deficiencies, the sooner we can help remedy their effects and prevent possible future pain and suffering.
The medical profession justifiably encourages screening tests for preventative purposes. What profession is better qualified than Chiropractic to screen, correct, and prescribe procedures to prevent the crippling, degenerative effects of leg length discrepancies? We all wish to live longer. However, we wish to do so in good health. The Chiropractic profession should help assure society of its input. It should assure our aging into a more pain-free future.
1. Friberg O. Leg length asymmetry in stress fractures: a clinical and radiographic study. J Sports Med Phys Fitness 1982; 22:485-488.
2. Giles LGF, Taylor JR. Lumbar spine structural changes associated with leg length inequality. Spine 1982; 7:159-162.
3. Macaw ST, Bates BT. Biomechanical implications of mild leg inequality. Br J Sports Med 1991; 25:10-13.
4. Austin WM. Chiropractic health for recreational runners. JACA 2002; 39(5):34.
About the Author
Dr. John Palo is a Board Certified Chiropractic Orthopedist, Certified Chiropractic Sports Physician, Instructor Emeritus for the New York Chiropractic College Orthopedist Diplomate Program, and former Assistant Director of the Chiropractic Division of the New York City Department of Health. He is the author of the cartoon-style illustrated text, Basic Orthopedic and Neurological Tests for the Office, and, more recently, the book, Take Care of Your Back! His is in practice in Manhattan, New York.