Limb Length Discrepancies of the Lower Extremity (The Short Leg Syndrome)

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1 /81/ $02.00/0 THE JOURNAL OF ORTHOPAED~C AND SPORTS PHYSICAL THERAPY Copyright O 1981 by The Orthopaedic and Sports Physical Therapy Sections of the American Physical Therapy Association Limb Length Discrepancies of the Lower Extremity (The Short Leg Syndrome) STEVEN I. SUBOTNICK,* DPM, MS A survey of over 4,000 athletes and long distance runners, seen in my office over the past 6 years, reveals almost 40% of some form of limb length discrepancy. The limb length discrepancy is oftentimes associated with functional abnormalities, such as overpronation of one foot in contradistinction to the other or imbalances within the pelvis itself. Likewise, anatomical or true shortness may be present or a combination of anatomical and functional discrepancies. There appears to be a high correlation of injury on the short leg side and also associated weakness with the shortening. Conversely, utilizing a heel lift for a functional problem may cause contralateral symptoms. That being the case, it appears appropriate for practitioners involved in treating athletes to be aware of the various forms of limb length discrepancies that may exist, their significance, and their appropriate treatment. INTRODUCTION I have been familiar with the importance of limb length discrepancies in sports medicine for the past several years. My first paper was written prior to Dr. Karl Klein has also helped me appreciate the significance of these discrepancies, and he published his earlier accounts in Since my earlier publications, clinical experience has allowed me to refine my original thoughts on this subject, and this paper is a representation of my current understanding. Asymmetries of limb length which cause lateral tipping of the pelvis and minor degrees of spinal curvature have been reported frequently in the literature.' '-I2 Pearson's" progressive standing radiological study of 830 school children from 8 to 13 years of age indicated that 93% had some degree of lateral asymmetry. Though compensation does occur, the structural asymmetry does not improve materially. Klein5 demonstrated in 1953 that the greatest change in the development of lateral asymmetry occurs between the elementary and junior high school years, but the pro- ' Professor, California College of Podiatric Medicine: President. American Academy of Podiatric Sports Medicine: Fellow, American College of Sports Medicine; Fellow, American College of Foot Surgeons. cess continues into the senior high school ages. Both Klein and Buckleys and Fahey3 noted the relationship between foot pronation and lateral asymmetry. Anderson1 stated that asymmetries of 3/4-11/2 inches require foot correction or a heel lift. Limb length discrepancies of less than 3/4 inch need no correction, inasmuch as spontaneous compensation will take place. However, this author has found that limb length discrepancies of I/' inch or more, when associated with imbalance symptoms, do need correction. Limb length discrepancies greater than % inch require a forefoot lift of about one-half the thickness of the heel lift to prevent equinus;' deviations of over 11/2 inch may need a prosthetic device or shoe modifications; and major discrepancies may require sur- gery. It has been my experience that at least 40% of my athlete patients have some form of limb length discrepancy. The limb length discrepancy may be functional, anatomical, or a combination of both. It may be associated with an injury or the primary cause of the injury. Limb length discrepancies of the lower extremity often cause disabling problems for runners. Although major limb length discrepancies are at a young age, minor discrepancies are frequently unnoticed until symp-

2 12 SUBOT 'NICK JOSPT Vol. 3, No. 1 toms ranging from low back pain to sciatica develop.2, 4. 5, " A careful examination of the patient may reveal asymmetry of the pelvis secondary to an anatomical or functional shortening of one limb. Pain in the low back, pelvis, or hip or pain which radiates down the thigh (sciatica) can be secondary to other causes, including primary nerve disease or secondary nerve involvement.' A third cause is low back strain which often accompanies asymmetry of the lower extremities. When examination has eliminated other causes of sciatica in the presence of limb length discrepancies, heel lifts or orthoses can transform a runner with nagging, almost disabling pain into a pain-free athlete. TYPES OF LIMB LENGTH DISCREPANCIES The basic measurement procedure for determining the symmetry or asymmetry of the posterior iliac spines is that recommended by Lowman," Redler,12 and Klein and Buckley.' Lateral pelvis imbalance of 'h inch or more is recorded and determined by the thickness of the heel lift necessary to achieve balance of the pelvis (posterior iliac spine) and spinal column with the patient standing. The patient should stand on a low table with feet slightly apart, legs parallel, knees straight ahead, and arms hanging naturally to the sides. The investigator should palpate the posterior superior iliac spine. Calibrated blocks of %6 inch should be added until the pelvic spines are level. This measurement is basically for anatomical limb length discrepancies. It fails to take into account the functional limb length discrepancy secondary to unilateral excessive pronation of a foot or low back imbalances. In the final analysis, what is important is that the pelvis be level during neutral stance. One must also differentiate between functional and anatomical limb length discrepancies, and the level of imbalance must be determined. Work among the advocates of applied kinesiology has shown that an unnecessary heel lift results in a unilateral weakness. An uncorrected limb length discrepancy likewise results in unilateral weakness. I prefer to examine my patients in several attitudes and positions. The patients are examined sitting and standing. They are examined lying down prone and supine. Measurements are taken from the anterior superior iliac crest at the medial malleolus of both legs and compared. With the patient sitting, one observes if a sco- liosis is present. When the patient is standing, the level of the pelvis is recorded, the amount of lifts necessary for a level pelvis is noted, and the presence or absence of scoliosis is noted. The type of scoliosis and the level at which it occurs is recorded. If the scoliosis disappears with sitting, then it is assumed to be functional. If the scoliosis persists with sitting, it may be part of the cause of the limb length discrepancy. It may, likewise, be the result of a limb length discrepancy and be more advanced in nature. The presence or absence of paraspinal spasm is noted. This is recorded in the chart and checked on the next visit. Variations in the limb length between the supine and prone position are noted and may be accounted for by bipositional abnormalities of the pelvis, sacroiliac joints, or low back. The organic abnormalities could result in spasm which would also be present with these positional variations. I prefer to classify three types of limb length discrepancies. The first is anatomical. It is actual shortening of the limb, causing a tilt of the pelvis and a secondary compensation of the spinal column and resulting in scoliosis (Fig. 1 A). The second is functional. It is secondary to abnormal hip positioning with the muscle spasm or abnormal foot positioning causing abnormal pelvis rotation (Fig. 1 B). It may also be caused by malposition or spasm of the low back, sacroiliac joints, or pelvis area. One must rule out organic causes of low back strain contributing to pelvis malrotation and scoliosis. The third is a combination of anatomical and functional discrepancies. With structural limb length discrepancy, both anterior and posterior portions of the pelvis will usually be low on the side of the short leg. Measurements of the patient supine and prone will confirm the limb length discrepancy. There may be a compensating curve of the spine convex to the short leg side. This usually disappears during sitting. The shoulder blade (scapula) on the long limb side will drop, and the arm on the long leg side will appear longer than the arm on the short leg side. If scoliosis is secondary to the limb length discrepancy, it will disappear when the patient is seated. If the limb length discrepancy is secondary to scoliosis or pelvic problems, it will persist while seated. A flexible curvature of the spine may become less flexible and less rigid with the passing of time. The patient with the short leg syndrome may compensate by externally rotating his foot

3 JOSPT Summer LIMB LENGTH DISCREPANCIES Fig. 1. Anatomical short leg (A), functional short leg (B), and disappearance of functional short leg with orthotic control (C). (Reprinted with permission from "Podiatric Sports Medicine, " Steven I. Subotnick, DPM, MS, author, published by Futura Publishing Co., Mt. Kisco, NY, 1975.) and leg to provide for stability.' This complicates the problem because an externally rotated foot also has a valgus of the heel and associated collapse of the arch.13 External rotation of the leg on an internally rotated femur causes the knee joint to suffer. Klein7 commented on the relationship between externally rotated legs and knee joint pathology among athletes. If the patient has a functional limb length discrepancy at the foot level, the foot on the short leg side will be externally rotated with the heel in valgus and the medial arch collapsed. The patient with true limb length discrepancy, who compensates for lateral instability by externally rotating the foot, has the same appearance. When the patient with functional discrepancy is examined, the rear pelvic spine may appear higher than the front pelvic spine on the short leg side. The internal rotation of the leg and the thigh, which accompanies pronation or flattening of the foot, causes the pelvis to rotate asymmetrically, thus lowering the anterior pelvic spine and raising the posterior pelvic spine. When there is functional imbalance in the low back or pelvis, there oftentimes will be posterior rotation of the pelvis on the short leg side. The importance of functional imbalance in the pelvis and low back has been largely ignored until recently. For many years, many of my patients would be measured and fitted for heel lifts and then go to a chiropractor for adjustments of their low back. They would return and no longer need the heel lift or indeed need a lift on the opposite side. It was noted that many of the scoliosis deformities previously present were absent after chiropractic manipulation. Reviewing the literature and speaking with orthopedists, chiropractors, and osteopaths has led to this conclusion: there can be functional imbalances in the pelvis and low back similar to the imbalances elsewhere in the body, and indeed, mobilization, manipulation, and physical therapy may be indicated. One must rule out, at all times, any organic causes of low back pain or associated radiating pain to the lower extremities. It is easily observed that pronation of both feet causes an accentuated lumbar lordosis. This lordosis may result in low back pain. The use of orthotics for mobile flat feet associated with excessive lordosis oftentimes eases the low back pain. Orthotics also help with pelvic malrotation which may result in low back pain. Orthotics may not cure the problems but do indeed help them. Sciatica likewise may be relieved with orthotic

4 14 SUBOTNICK JOSPT Vol. 3, No. 1 foot control when significant biomechanical abnormalities are present in the lower extremities. DIFFERENTIAL DIAGNOSIS OF LIMB LENGTH DISCREPANCIES To examine for structural limb length discrepancy, both heels should be placed in a perpendicular or neutral position with the arches of both feet as close to normal as possible in normal gait angle.i3 The posterior pelvic spines should be palpated and differences in elevation noted. The anterior pelvic spines should likewise be palpated and noted. The compensation in a true limb length discrepancy is ascertained by building up the heel of the short leg side, using different thicknesses of blocks until the iliac spines are level. If the discrepancy is discovered in childhood or early adulthood, this cpmpensating treatment may cause the curvature of the spine to disappear and improve the angle of gait. For a functional limb length discrepancy at the level of the foot, both heels should be placed in neutral position or close to vertical with the arches of both feet normal. This will cause the anterior and posterior iliac spines to become level, the limb length discrepancy to disappear, and the curvature of the spine to straighten. The treatment of functional limb length discrepancy within the foot is therefore neutral arch control. This is accomplished by using orthotic devices made over a cast of the patient's foot while the foot is held in position of maximum function, the neutral position. Functional limb length discrepancies of the back are noted by flexible scoliosis persistent in neutral stance and in sitting. One may observe that, even though the pelvis is level, the scoliosis persists with heel lifts, and this is similar to the scoliosis present during sitting. Scoliosis may be present with or without associated paraspinal spasm. This type of functional limb length discrepancy is best treated by physical medicine techniques including mobilization, gentle manipulation, and exercises to strengthen all muscles about the low back and pelvis. Additional physical therapy such as ultrasound may be indicated if there is low back strain present. If any neurological abnormalities are found in the lower extremities, orthopedic or neurological consultation is necessary. Likewise, if history or physical findings are consistent with an organic lesion, orthopedic consultation should be sought. X- Rays and a neurological workup are indicated if one considers a disc to be present with the symptomatology. Occasionally, combinations of anatomic and functional limb length discrepancies will occur, and it may be necessary to prepare'orthoses with a heel lift on the short leg side. At times, patient reactions are contrary to predictions. The patient's foot may function slightly pigeon-toed on the short leg side, causing the arch of the foot to be elevated with external rotation of the leg as the foot is planted on the ground. The elevation of the arch may also cause some leveling of the pelvis. SYMPTOMS ACCOMPANYING LIMB LENGTH DISCREPANCIES It has been my observation that most people externally rotate the short legged side. This external rotation is accompanied by the majority of the weight being medial to the foot. This causes excessive pronation of the foot and likewise excessive medial strain on the entire lower extremity. There tends to be an increase therefore of overuse injuries associated with the medial structures of the lower extremity and likewise the medial longitudinal arch. There is an increased incidence of chondromalacia patella in athletes due to the increase of the functional Q angle at the knee. This causes a tendency towards lateral overriding of the patella on the lateral femoral condyle. This loss of proper tracking accounts for the majority of peripatellar pain in athletes. A myriad of overuse injuries ranging from greater trochanteric bursitis, to iliotibial band strain, to flexor group shin splints or anterior tibial shin splints, and finally to medial ankle synovitis, posterior tibial tendinitis, and medial plantar fascitis must be included. The observed weakness on the short side may also contribute to the higher incidence of overuse injuries. Symptoms accompanying limb length discrepancies include sciatica and generalized low back ~ain.~,'~ Pain in the hip joint and pain along the outside of one thigh and iliotibial band may accompany low back pain. Sciatica is a radiating nerve pain beginning in the low back and running down the inside of the thigh, sometimes to the inside of the foot. The pain is accentuated when the patient lies on his back and attempts a straight leg raise. The pain is also more severe when running uphill. Sciatica pain is often pres-

5 JOSPT Summer 1981 LIMB LENGTH DISCREPANCIES 15 ent on the short leg side and may be associated with low back strain or herniation of an intervertebral disc.i4 Primary and secondary nerve involvement must be ruled out. When sciatica is secondary to limb length discrepancy, the response to a heel lift or an orthosis is dramatic. Failure to obtain dramatic relief would indicate further consultation with other medical specialists. Low back pain or back strain may be associated with sacroiliac joint involvement, a nagging pain over the buttocks. The patient would feel more comfortable seated and resting on the noninvolved buttocks. This pain also presents a formidable list of possible causes which should be investigated before the diagnosis of pain is deemed secondary to limb length discrepancy. SUMMARY In summary, the importance of proper examination of the patient with limb length discrepancy has been presented. The importance of determining the level of deformity is also discussed. It is noted that neutral orthotic foot control will take care of functional limb length discrepancies with their origin in the feet and anatomical limb length discrepancies are secondary to under- or overdevelopment of the length of bone and are corrected with appropriate heel lift. I find it most useful to use full lift in the heel and one-half of this amount under the ball of the foot with onefourth of the amount under the toes. Thus, a patient with a 1 -inch short leg would have 1 -inch buildup at the heel, M-inch buildup at the ball of the foot, and %-inch buildup under the toes. This wedge buildup appears to be more functional than a straight I-inch lift for the entire sole of the shoe. The lift may be placed in the midsole and can be drilled to allow for weight reduction in regards to running shoes or basketball shoes. When a lift is utilized, a lateral flare on the shoe or boot may be necessary inasmuch as the lift may preclude increased lateral instability of the foot and ankle. Within the shoe or boot, lifts just short of '/2 inch may be used with success. For combinational limb length discrepancies occurring secondary to foot imbalance and anatomical discrepancy within the leg, orthotic foot control with the lift built into the orthoses is most useful. An example of this would be an orthot~c device, full length, with 3/e-inch heel lift, 3/16-inch lift under the metatarsal heads, and '/&inch lift under the toes. The amount of varus tilt on this orthosis would be reduced inasmuch as the heel lift tends to supinate the calcaneus. Minor limb length discrepancies which would cause little difficulty in the nonathlete can cause significant symptoms in the active athlete. This is because of the rule of three. The rule of three represents the fact that, in running, three times the body weight goes through the support limb whereas, in walking, about one times the body weight is transmitted through the support limb. Thus, biomechanical abnormalities of the lower extremity tend to be three times more significant in running than in walking. The rule of three is illustrated by a patient with '/&inch limb length discrepancy having no discomfort during walking yet chronic repetitive overuse injuries on the short leg side during running. The '/4-inch limb length discrepancy is as important as a 3/4-inch limb length discrepancy in the nonathletic patient. Athletes require symmetrical body frames. Symptoms secondary to structural or functional limb length discrepancies frequently respond dramatically to heel lifts and/or orthotic foot control. Functional abnormalities secondary to muscle imbalance or malrotation of bones in the pelvis and low back must be dealt with appropriately by other professionals. The importance of proper diagnosis cannot be overstressed. One must always be mindful of organic causes of low back strain which may range from inflammatory autoimmune diseases, to discogenic disease, to cancer. Appropriate referral and consultation is necessary. One most utilize laboratory tests and X-rays in establishing a differential diagnosis. REFERENCES 1. Anderson WV: Modern Trends in Orthopedics, pp New York: Appleton-Century-Crofts, Beal MC: Review of short leg problem. J Am Osteopath Assoc 50: , Fahey JF: Retarded leg syndrome (mimeo). Hollywood. CA Green WT: Discrepancy in leg length of lower extremities. American Academy of Orthopaedic Surgeons Instructional Course Lectures. VIII. Ann Arbor, MI: JW Edwards Co, Klein KK: Progression ot pelvic tilt in adolescent boys from elementary through high school. Arch Phys Med Rehab11 54:57-59, Klein KK: Comparison of asymmetries in pelvis and legs of elementary and junior high school boys ( ) (mlmeo). Department of Physical Education for Men. University of Texas at Austin, Austin, TX, Klein KK: Flexibility-strength and balance in athletics. J Natl Athletic Training Assoc 6:62-65, Klein KK. Buckley JC: Asymmetries of growth in pelvis and legs of growing children: summation of three-year study ( ). Am Correct Ther J 22:53-55, Lovett RW: Lateral Curvature of Spine and Round Shoulders.

6 16 SUBOTNICK JOSPT Vol. 3, No. 1 Chaps and 9. Philadelphia: Blakiston's Son and Co Lowman CL, Colestock C. Cooper H: Corrective Physical Education for Groups. p 63. New York: AS Barnes 8 Co, Inc, Pearson WM: Progressive structural study of school children. J Am Osteopath Assoc 51 :I , Redler I: Clinical significance of minor inequalities in leg length. New Orleans Med Surg J 104: Sgarlato TE: A Compendium of Podiatric Biomechanics, pp San Francisco: CCPM, Wiltse I: The effect of the common anomalies of the lumbar spine upon disc degeneration and low back pain. Orthop Clin North Am 2: , 1971 BIBLIOGRAPHY I. Subotnick SI: Podiatric Sports Medicine, pp Mt. Kisco. NY: Futura Publishing Co, Subotnick St: The Running Foot Doctor. Mountain View. CA: World Publications Subotnick SI: Cures for Common Running Injuries. Mountain View, CA: World Publications Subotnick SI: Case history of unilateral short leg with athletic overuse injury. J Am Podiatry Assoc 70: , Subotnick SI: Low back pain from functionally short leg. J Am Podiatry Assoc 71 :