Unequal leg length

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Unequal leg length
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A girl with a congenital, structural difference in leg lengths walking in a clinic.
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Unequal leg length (also termed leg length inequality, LLI or leg length discrepancy, LLD) is often a disabling condition where the legs are either different lengths (structurally), or appear to be different lengths, because of misalignment (functionally).

Contents

Unequal leg length with a small degree of difference is very common; small inequalities in leg length may affect 40%–70% of the human population. It has been estimated that at least 0.1% of the population have a difference greater than 20 mm (0.79 in). As of June 2024, that is approximately 8.1 million people total in the human population. [1]

Classification

There are two main types of leg length discrepancy:

Diagnosis and workup

X-rays for leg length measurement. Leg length measurement on X-ray.jpg
X-rays for leg length measurement.

Unequal leg length in children is frequently first suspected by parents noticing a limp that appears to be getting worse. [3] The standard workup in children is a thorough physical examination, including observing the child while walking and running. [3] In the United States, standard workup in children also includes X-rays to quantify actual length of the bones of the legs. [3]

On X-rays, there is generally measurement of both the femur and the tibia, as well as both combined. [4] Various measuring points for these have been suggested, but a functional method is to measure the distances between joint surfaces: [4]

As previously mentioned, leg length difference can result from a repetitive activity that misaligns, one example being pelvic torsion; this is a functional LLD.

Abnormal (gravity drive) pronation will drive the innominate bones forward (anteriorly). The forward rotation of the innominate will shorten the leg. [5] The more pronated foot will have the more forwardly rotated innominate bone and will be the side with the functionally short leg.

In adults, leg length discrepancy causes pain and challenge to the kinetic chain of the body's structure and almost every other part of the body – even organs because of the spaces and connection the nerves demand throughout the joints of the body. They may therefore become impaired and can become dysfunctional, according to the severity of differentiation in the discrepancy. Balance issues often cause muscle deconditioning as the spinal column tries to compensate and bend more than is safe for the joint and nerve spacing in the spinal column, leading to more denervation and weakness. The increased weight and pressure of the longer leg on the shorter leg often leads to denervation and weakness. Sciatica and blood circulation in the lower limbs is impaired as well.

Low back pain will occur with increased pelvic obliquity; X-rays of the sacroilliac joint may help determine joint impingement and any lumbar scoliosis that often, if not always, occurs. [6]

Treatment

The most common treatment for discrepancies in leg length is the use of a simple heel lift; this is outdated, and may lead to foot cramping and discomfort. The modern remedy is a full orthotic insole or outsole lift which can be placed inside or outside the shoe. In cases where the length discrepancy is moderate, an external build up to the shoe is necessary to accommodate the foot spacing in most modern shoes. An improved method for addressing differences in leg length involves measuring and rectifying the disparities while standing upright and weight bearing. Adjustments of minor or significant biomechanical change can be made to the foot's angle and height to correct the discrepancies in real-time using a mechanical device like the Vertical Foot Alignment System (VFAS). This technique will take into account the changes that the foot goes through when under a weight-bearing condition including correct foot alignment, arch support and comfort.

The left shoe has greater height and weight bearing correction designed using VFAS. Custom shoes.jpg
The left shoe has greater height and weight bearing correction designed using VFAS.

In severe cases, surgery can be used to make the longer leg shorter (or impede its growth), and/or make the shorter leg longer via limb lengthening.

Measurement challenges

Although prone "functional leg length" is a widely used chiropractic tool in their Activator technique, it is not a recognized anthropometric technique, since most legs are usually only to a small degree unequal, and measurements in the prone position are not entirely valid estimates of standing X-ray differences. [7] Measurements in the standing position are far more reliable. [8] Since another confounding factor is that simply moving the two legs held together and leaning them imperceptibly to one side or the other produces different results. [9] [10]

VFAS is a mechanical device used to correct foot alignment while weight bearing Standing on the Vertical Foot Alignment System VFAS, When the dotted lines are straight, horizontal and vertical alignment is correct.jpg
VFAS is a mechanical device used to correct foot alignment while weight bearing

Clinical measurement of leg length conventionally uses the distance from the anterior superior iliac spine to the medial malleolus. [11] Projectional radiographic measurements of leg length have two main variants: [12]

On X-rays, the length of the lower limb can be measured from the proximal end of femoral head to the center of the plafond of the distal tibia. [13]

See also

Related Research Articles

<span class="mw-page-title-main">Human leg</span> Lower extremity or limb of the human body (foot, lower leg, thigh and hip)

The leg is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or buttock region. The major bones of the leg are the femur, tibia, and adjacent fibula. The thigh is between the hip and knee, while the calf (rear) and shin (front) are between the knee and foot.

<span class="mw-page-title-main">Femur</span> Thigh bone

The femur, or thigh bone is the only bone in the thigh. The thigh is the region of the lower limb between the hip and the knee. In many four-legged animals the femur is the upper bone of the hindleg.

<span class="mw-page-title-main">Knee</span> Leg joint in primates

In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia, and one between the femur and patella. It is the largest joint in the human body. The knee is a modified hinge joint, which permits flexion and extension as well as slight internal and external rotation. The knee is vulnerable to injury and to the development of osteoarthritis.

<span class="mw-page-title-main">Ankle</span> Region where the foot and the leg meet

The ankle, the talocrural region or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joint. The movements produced at this joint are dorsiflexion and plantarflexion of the foot. In common usage, the term ankle refers exclusively to the ankle region. In medical terminology," can refer broadly to the region or specifically to the talocrural joint.

An osteotomy is a surgical operation whereby a bone is cut to shorten or lengthen it or to change its alignment. It is sometimes performed to correct a hallux valgus, or to straighten a bone that has healed crookedly following a fracture. It is also used to correct a coxa vara, genu valgum, and genu varum. The operation is done under a general anaesthetic.

<span class="mw-page-title-main">Anterior cruciate ligament</span> Type of cruciate ligament in the human knee

The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments in the human knee. The two ligaments are also called "cruciform" ligaments, as they are arranged in a crossed formation. In the quadruped stifle joint, based on its anatomical position, it is also referred to as the cranial cruciate ligament. The term cruciate translates to cross. This name is fitting because the ACL crosses the posterior cruciate ligament to form an "X". It is composed of strong, fibrous material and assists in controlling excessive motion. This is done by limiting mobility of the joint. The anterior cruciate ligament is one of the four main ligaments of the knee, providing 85% of the restraining force to anterior tibial displacement at 30 and 90° of knee flexion. The ACL is the most injured ligament of the four located in the knee.

<span class="mw-page-title-main">Genu varum</span> Varus deformity marked by (outward) bowing at the knee

Genu varum is a varus deformity marked by (outward) bowing at the knee, which means that the lower leg is angled inward (medially) in relation to the thigh's axis, giving the limb overall the appearance of an archer's bow. Usually medial angulation of both lower limb bones is involved.

<span class="mw-page-title-main">Popliteal artery</span> Continuation of the femoral artery that supplies the lower leg

The popliteal artery is a deeply placed continuation of the femoral artery opening in the distal portion of the adductor magnus muscle. It courses through the popliteal fossa and ends at the lower border of the popliteus muscle, where it branches into the anterior and posterior tibial arteries.

<span class="mw-page-title-main">Hemipelvectomy</span> Surgical removal of half of the pelvis

Hemipelvectomy, also known as a pelvic resection, is a surgical procedure that involves the removal of part of the pelvic girdle. This procedure is most commonly performed to treat oncologic conditions of the pelvis. Hemipelvectomy can be further classified as internal and external hemipelvectomy. An internal hemipelvectomy is a limb-sparing procedure where the innominate bone is resected while preserving the ipsilateral limb. An external hemipelvectomy involves the resection of the innominate bone plus amputation of the ipsilateral limb.

<span class="mw-page-title-main">Hip</span> Anatomical region between the torso and the legs, holding the buttocks and genital region

In vertebrate anatomy, the hip, or coxa in medical terminology, refers to either an anatomical region or a joint on the outer (lateral) side of the pelvis.

<span class="mw-page-title-main">Proximal femoral focal deficiency</span> Medical condition

Proximal femoral focal deficiency (PFFD), also known as Congenital Femoral Deficiency (CFD), is a rare, non-hereditary birth defect that affects the pelvis, particularly the hip bone, and the proximal femur. The disorder may affect one side or both, with the hip being deformed and the leg shortened.

<span class="mw-page-title-main">Tibial nerve</span> Branch of the sciatic nerve

The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus.

The biceps femoris is a muscle of the thigh located to the posterior, or back. As its name implies, it consists of two heads; the long head is considered part of the hamstring muscle group, while the short head is sometimes excluded from this characterization, as it only causes knee flexion and is activated by a separate nerve.

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<span class="mw-page-title-main">Stifle joint</span>

The stifle joint is a complex joint in the hind limbs of quadruped mammals such as the sheep, horse or dog. It is the equivalent of the human knee and is often the largest synovial joint in the animal's body. The stifle joint joins three bones: the femur, patella, and tibia. The joint consists of three smaller ones: the femoropatellar joint, medial femorotibial joint, and lateral femorotibial joint.

<span class="mw-page-title-main">Cruciate ligament</span> Type of ligament shaped like an X

Cruciate ligaments are pairs of ligaments arranged like a letter X. They occur in several joints of the body, such as the knee joint, wrist joint and the atlanto-axial joint. In a fashion similar to the cords in a toy Jacob's ladder, the crossed ligaments stabilize the joint while allowing a very large range of motion.

<span class="mw-page-title-main">Pigeon toe</span> Medical condition affecting the feet

Pigeon toe, also known as in-toeing, is a condition which causes the toes to point inward when walking. It is most common in infants and children under two years of age and, when not the result of simple muscle weakness, normally arises from underlying conditions, such as a twisted shin bone or an excessive anteversion resulting in the twisting of the thigh bone when the front part of a person's foot is turned in.

<span class="mw-page-title-main">Pelvis</span> Lower torso of the human body

The pelvis is the lower part of the trunk, between the abdomen and the thighs, together with its embedded skeleton.

<span class="mw-page-title-main">Medial knee injuries</span> Medical condition

Medial knee injuries are the most common type of knee injury. The medial ligament complex of the knee consists of:

Bone malrotation refers to the situation that results when a bone heals out of rotational alignment from another bone, or part of bone. It often occurs as the result of a surgical complication after a fracture where intramedullary nailing (IMN) occurs, especially in the femur and tibial bones, but can also occur genetically at birth. The severity of this complication is often neglected due to its complexity to detect and treat, yet if left untreated, bone malrotation can significantly impact regular bodily functioning, and even lead to severe arthritis. Detection throughout history has become more advanced and accurate, ranging from clinical assessment to ultrasounds to CT scans. Treatment can include an osteotomy, a major surgical procedure where bones are cut and realigned correctly, or compensatory methods, where individuals learn to externally or internally rotate their limb to compensate for the rotation. Further research is currently being examined in this area to reduce occurrences of malrotation, including detailed computer navigation to improve visual accuracy during surgery.

References

  1. Gurney, Burke (2002-04-01). "Leg length discrepancy". Gait & Posture. 15 (2): 195–206. doi:10.1016/S0966-6362(01)00148-5. ISSN   0966-6362. PMID   11869914. LLD is a relatively common problem found in as many as 40 [1] to 70% [2] of the population. In a retrospective study, it was found that LLD of greater than 20 mm affects at least one in every 1000 people [3].
  2. Knutson G. A. (2005). "Anatomic and functional leg-length inequality: A review and recommendation for clinical decision-making. Part II, the functional or unloaded leg-length asymmetry". Chiropractic & Osteopathy. 13 (12): 12. doi: 10.1186/1746-1340-13-12 . PMC   1198238 . PMID   16080787.
  3. 1 2 3 "Leg Length Discrepancy (Pediatric)". Columbia University . Retrieved 2019-02-14.
  4. 1 2 Sabharwal, Sanjeev; Kumar, Ajay (2008). "Methods for Assessing Leg Length Discrepancy". Clinical Orthopaedics and Related Research. 466 (12): 2910–2922. doi:10.1007/s11999-008-0524-9. ISSN   0009-921X. PMC   2628227 . PMID   18836788.
  5. Rothbart, Brian A. (2006). "Relationship of Functional Leg-Length Discrepancy to Abnormal Pronation". Journal of the American Podiatric Medical Association . 96 (6): 499–507. doi:10.7547/0960499.
  6. Needham, R.; Chockalingam, N.; Dunning, D.; Healy, A.; Ahmed, E. B.; Ward, A. (2012). "The effect of leg length discrepancy on pelvis and spine kinematics during gait". Research into Spinal Deformities 8: 104–107. doi:10.3233/978-1-61499-067-3-104.
  7. D W Rhodes, E R Mansfield, P A Bishop, J F Smith. The validity of the prone leg check as an estimate of standing leg length inequality measured by X-ray. J Manipulative Physiol Ther.; 18 (6):343-6
  8. Hanada E, Kirby RL, Mitchell M, Swuste JM (Jul 2001). "Measuring leg-length discrepancy by the "iliac crest palpation and book correction" method: reliability and validity". Arch Phys Med Rehabil. 82 (7): 938–42. doi:10.1053/apmr.2001.22622. PMID   11441382.
  9. Rothbart, Brian A. (2013). "Prescriptive Insoles and Dental Orthotics Change the Frontal Plane Position of the Atlas (C1), Mastoid, Malar, Temporal and Sphenoid Bones: A Preliminary Study". Journal of Craniomandibular & Sleep Practice. 31 (4): 300–308. doi:10.1179/crn.2013.31.4.008.
  10. "Adjusting the Joints, on season 12, episode 10". Scientific American Frontiers . Chedd-Angier Production Company. 2001–2002. PBS. Archived from the original on 2006-01-01.. Video discusses Activator technique and leg length
  11. Page 305 in: M. Lynn Palmer, Marcia E. Epler, Marcia F. Epler (1998). Fundamentals of Musculoskeletal Assessment Techniques. Lippincott Williams & Wilkins. ISBN   9780781710077.{{cite book}}: CS1 maint: multiple names: authors list (link)
  12. Page 269 in: Dror Paley (2002). Principles of Deformity Correction, Volume 1. Springer Science & Business Media. ISBN   9783540416654.
  13. Sabharwal, Sanjeev; Zhao, Caixia; McKeon, John; Melaghari, Todd; Blacksin, Marcia; Wenekor, Cornelia (2007). "Reliability Analysis for Radiographic Measurement of Limb Length Discrepancy". Journal of Pediatric Orthopaedics. 27 (1): 46–50. doi:10.1097/01.bpo.0000242444.26929.9f. ISSN   0271-6798. PMID   17195797. S2CID   38224649.