Every human body, even though structured to be bilaterally symmetrical, presents some degree of asymmetry. The questions are: How much is too much? What is clinically significant? What can be done to reduce pain and structurally stabilize the patient?

Most standard clinical examinations cannot detect leg length inequality (LLI) less than 25 mm (approximately 1 inch), and patients themselves may be unaware of the condition. Some practitioners consider such discrepancies mainly cosmetic, while most chiropractors recognize LLI as a primary or contributing cause of low-back pain, unilateral hip arthrosis, and lower extremity stress.1

Giles reported that a leg length inequality of greater than 10 mm leads to asymmetric vertebral body height, asymmetric endplates and traction spurs, i.e. degeneration due to focal weight-bearing.2,3

In the early 1980’s, Ora Friberg, a Finnish Orthopaedist, looked at over 1000 army recruits and found that over 75% of those which had a history of chronic low back pain, hip pain and/or sciatica had a leg length inequality (measured at the femur head height) of 5 mm or more.1 Interestingly, of those who had a history of hip pain, 79% experienced it on the ‘long’ leg side and of those with sciatica, 89% was again on the ‘long’ leg side.

Using these as rough guidelines, we might consider that 5 mm is significant for pain. Those individuals with a LLI of 5 mm or greater are more apt to develop low back pain. And a LLI greater than 10 mm might predispose that individual to degenerative joint disease (DJD) secondary to biomechanical malposition.

LLI can be categorized as structural or functional. Both types evoke similar responses in the musculoskeletal system when present for sustained periods.1

A low femur head height and/or a low sacral base and/or a low iliac crest height — though they may appear in any combination, typically we see all three deficiencies on the same side (see Fig. 1). The body of the lowest freely moveable lumbar vertebral normally rotates to the low side. Therefore the convexity of the curve will typically be on the low side.

The prevalence of LLI was documented more than 40 years ago in various references in osteopathic literature (see Table 1).3

Defining LLI

Leg length insufficiency can occur due to anatomical causes such as unequal growth rates, trauma — including fractures and surgery, congenital deformities, degeneration, infection, and neoplasms. Such a case is referred to as structural or anatomical LLI.

Functional LLI refers to leg length differences not attributed to anatomical deficiency. Commonly spoken of in chiropractic literature, the functional or physiological short leg results from biomechanical causes anywhere within the lower kinetic chain such as pelvic rotation, excessive foot pronation, muscle contractures, or pelvic and sacral subluxations.

Structural and functional LLI exhibit a similar presentation as outlined above. In clinical practice, it is the functional LLI that is generally more prevalent and also more responsive to therapy — both pain reduction and structural realignment.

The structural misalignment that typifies prolonged cases of LLI affects muscular pull and the amount of weight borne by the joints. The body can tolerate such abnormalities for short periods, but when weight and pull fall abnormally on the musculoskeletal system, serious and often subtle consequences can occur. The body’s adaptation resources become exhausted, and routine movements require greater muscular effort. Endurance is reduced and strain on the body increases.5 Stress can be transmitted to the ligaments, creating a vicious cycle of misalignment, muscle fatigue, and ligament stress (see Fig. 2).

The problems of functional LLI are especially troubling in endurance activities and those requiring fine balance or equal leg strength and control.6 Patients who spend a great deal of time on their feet, athletes, and other active individuals are most likely to exhibit clinical symptoms related to LLI.

Clinical Complications

Studies within the past two decades have identified various signs and symptoms that accompany LLI:

• Klein noted a predisposition to knee injuries in high school athletes with LLI. He found that the ankle on the side of LLI commonly experienced excessive pronation as the foot was planted on the ground, forcing the foot outward and causing excessive tibial torsion.7,8

• A negative effect on oxygen usage in subjects with LLI has been documented.9

• A subsequent study verified that shoe lift therapy could improve oxygen consumption.10

Examination Procedures

Both visual and radiographic procedures can be employed to detect the presence of leg length insufficiency. Greater accuracy of results will be achieved with the latter technique.11,12

Radiographic examination is the more widely accepted method of evaluating LLI. Two methods are in common use:

• Standing A-P Pelvis: A carefully-positioned weightbearing A-P radiograph of the pelvis is useful in evaluating for LLI, particularly if undetected clinically. The patient stands barefoot for an A-P pelvis with the central beam centered to the anterior superior iliac spine (ASIS). Placement of the feet squarely beneath the femoral heads will also reduce any tendency for the pelvis to sway to either side.

• Standing A-P Lumbopelvic: The patient stands barefoot for an A-P view of the lumbar spine and pelvis with the central ray centered at or just below the iliac crests. This method is less acceptable because of the inherent distortion created by central beam divergence. This divergence may amplify femoral head deficiency when pelvic obliquity is present (i.e., the more anterior femoral head will be projected lower on the radiograph).13

Remember, that with either method, the measured distortion at the femur head height, sacral base or iliac crest only tells you the amount of discrepancy, not if it is functional or anatomical.

Clinical examination may suggest an LLI but an anatomically short leg should be confirmed with a thorough history and x-ray measurements of the involved bones and/or joints.

When it appears that the leg length inequality is functional versus anatomical (which is typically the case with 90% of our chiropractic patients), check the patient for excessive pronation or supination. Both asymmetrical pronation and a symmetrical supination can contribute to pelvic unleveling. Harrison states that “asymmetrical pronation has the effect of producing pelvic tilt…”14 And Carpintero found a significant correlation between pes cavus (a high arched foot) and scoliosis.15

When your patient presents with pelvic unleveling and a functional short leg, check for either excessive pronation or supination. When present, support the foot with the proper orthotics before using a heel lift.

The initial x-rays should be taken without shoes on as previously mentioned. However, the follow-up radiographs should be taken with the patient wearing good shoes with the orthotics in place. Comparison radiographs with orthotics can provide insight as to the amount of correction achieved with a particular orthotic. These are typically taken 4-6 weeks later so that you can see the effect that your chiropractic adjustments along with the orthotic support is having on the patient. When the amount of pelvic distortion and lateral pelvic tilt are minimized, other postural aberrations may consequently resolve. Ideally, the new measurement should be less than 10 mm (clinically significant for DJD) and preferably less than 5 mm (clinically significant for pain).

Figures 3A & 3B demonstrate a typical example of the benefits of corrective orthotics. The pre-orthotic radiograph (Fig. 3A) shows a 15.5 mm functional LLI on the right. This deficiency was reduced to 4 mm on the follow-up radiograph (Fig. 3B) taken with the full length Spinal Pelvic Stabilizer Orthotic by Foot Levelers. Not only has the pelvic deficiency been markedly reduced, but the right compensatory listing of the lower lumbar spine has also diminished.

Not every case will resolve to this extent, as many other factors — such as age, overall health, degeneration etc. — will play a role. However, I anticipate, based on personal clinical experience, that on the average, a functional deficit can be reduced by one-half or 5-7 mm — whichever is greater.

Anatomical or Structural LLI and Lifts

As a general rule, “Make haste slowly”. Most of these cases are chronic — they’ve been there a long time and the body has compensated for this distortion. If a structural change is induced rapidly, this may cause a new painful compensatory reaction.

First, examine the patient for pedal imbalance as mentioned above. If present, cast the patient for the proper orthotics. Order the orthotic with a 3 mm Velcro heel lift and take it off when the orthotic comes in. Foot Levelers’ adjustable heel lifts give you the flexibility to vary the heel lift height.

Initially, have the patient wear only the orthotics for about two to four weeks. This allows time for the patient to get used to the orthotics and reduce biomechanical compensations induced by the functional component superimposed on the structural deficit. At the end of this period, clinically reassess the patient for the need of a lift. This is done through clinical examination and re-x-ray (in shoes with orthotics). Remember that some change may occur with using only the orthotics even with known anatomical leg length inequalities. If you feel that a lift is still necessary, proceed slowly.

As a general rule lifts are used on the side to which the body of the lowest freely moveable vertebrae has rotated. Starting with 3 mm the height can be increased as tolerated by the patient. Usually, two weeks per height increase allows enough time for the patient to adjust to the new position. Some patients may take more time to adjust — proceed slowly. Typically, one-half the femur head height discrepancy is the amount of heel lift necessary for full correction. Follow-up x-rays are the best way to be sure.

Clinical Management Options

Effective clinical management of LLI depends on careful examination of three primary factors:

• Origin of leg inequality.

• Degree of inequality.

• Age of patient.

It is important to remember that the body compensates for deficiencies which occur during its growth phase. Once the growth phase is complete, this compensation can alter the postural attitude. It should be noted that most postural deficits have their onset by the beginning of puberty.

 Table 2 is a useful guide to determining the most appropriate use of orthotics and lifts for LLI care.16

In Summary

Differences in leg lengths, structural or functional, are common. Methods utilized to evaluate these differences are subject to examiner variability. Radiographic procedures are more commonly relied upon as the standard but clinical observation techniques are widely applied.

The association between leg length inequalities and symptoms of back pain, leg pain, pelvic obliquity, and associated scoliotic deviations of the lumbar spine are well documented. The value of structurally compensating for the deficiency has proved to be beneficial.

The effectiveness of chiropractic adjustive procedures for LLI is enhanced when the body’s functional integrity is given therapeutic orthotic support and lifts when necessary. When selecting a lab to create a patient’s orthotics, choose one that offers a wide range of flexible orthotic styles that can be fitted with adjustable lifts for enhanced performance.

The general conclusion one might draw from Friberg’s extensive study of LLI indicates that at least 75 percent of the population has some degree of LLI. Furthermore, studies indicate that proper management of LLI, through use of lifts and orthotics, yields optimal results.

References
1. Friberg O. Clinical symptoms and biomechanics of lumbar spine and hip joint in leg length inequality. Spine 1983; 8:643-650.
2. Giles LGF, Taylor JR. Lumbar spine structural changes associated with leg length inequality. Spine 1982; 7:159-162.
3. Giles LGF, Taylor JR. Low back pain associated with leg length inequality. Spine 1981; 6:510-521.
4. Beal MC. A review of the short-leg problem. JAOA 1950; 50(2):190-121.
5. Schafer RC. Chiropractic Management of Sports and Recreational Injuries. Baltimore: Williams and Wilkins, 1982.
6. Hlavac HF. The Foot Book Advice for Athletes. Mountain View: World Publications, 1977.
7. Klein KK. Development asymmetries of the weightbearing skeleton and its implication in knee stress and knee injury. Athletic Training 1978; 13(2):78-80.
8. Klein KK. Development asymmetries of the weightbearing skeleton and its implication in knee stress and knee injury: a continuing report. Athletic Training 1982; 18:207-208.9.
9. Delacerda FG, McCrory ML. A case report: effect of leg length differential on oxygen consumption. J Orthop Sports Phys Ther 1981; 3:17-20.
10. Delacerda GG, Wikoff OD. Effect of lower extremity asymmetry on the kinematics of gait. J Orthop Sports Phys Ther 1982; 3:105-107.
11. Lawrence DJ. Chiropractic concepts of the short leg: a critical review. JMPT 1985; 8(3):157-161.
12. Shambaugh P, Scalfani L, Fanselow D. Reliability of the Derifield-Thompson test for leg length inequality and use of the test to demonstrate cervical adjusting efficacy. JMPT 1988; 11(5):396-399.
13. Lawrence DJ, Pugh J, Tasharski C, Heinze W. Evaluation of a radiographic method of determining short leg mensuration. J Am Chiro Assn 1984; 18:57-79.
14. Harrison D., et al. CPB, Vol. 4. 1988.
15. Carpintero P, et al. The relationship between pes cavus and idiopathic scoliosis. Spine 1994; 19:1260-1263.
16. Greenawalt MH. Spinal Pelvic Stabilization. Roanoke: Foot Levelers Educational Division, 1990: 61-2.