Pediatric Genu Varum
Pediatric Genu Varum
Genu varum is a Latin term used to describe bow legs. This condition may present from infancy through adulthood and has a wide variety of causes. As it becomes more severe, the patient may exhibit lateral knee thrust and a waddling gait. There may be associated in-toeing and secondary effects on the hip and ankle. The problem may be unilateral, with a functional limb-length discrepancy, or bilateral. The family and medical history may reveal clues to the likelihood of persistence or progression.
It is widely recognized that up to age 2 years, infants may have physiologic bowing of the lower extremities. The hallmark of this condition is symmetrical and painless bowing, usually associated with in-toeing and often with a propensity for tripping. This problem will resolve spontaneously without treatment, as a result of normal growth. [1, 2, 3] All that is required is parental education and periodic follow-up to verify resolution. During the wait for the predicted spontaneous correction, reversing the shoes may reduce the frequency of tripping.
The prevalence of this condition is not known, but it is frequent enough to be considered a variation of normal in toddlers. Nevertheless, it is a relatively common cause of parents’ seeking medical attention from their primary care providers, who should be knowledgeable in the triage of these conditions. Only in the most persistent or worrisome cases is orthopedic consultation warranted. Radiographs, though optional as a rule, may be needed to differentiate physiologic varus from pathologic conditions that call for treatment. 
In normal alignment, the lower-extremity lengths are equal, and the mechanical axis (center of gravity) bisects the knee when the patient is standing erect with the patellae facing forward (see the image below). This position places relatively balanced forces on the medial and lateral compartments of the knee and on the collateral ligaments, while the patella remains stable and centered in the femoral sulcus.
In children younger than 2 years, physiologic genu varum is common but is self-limiting and innocuous. In older children with pathologic genu varum, as the knee drifts laterally, the mechanical axis falls in the inner quadrant of the knee; in severe cases, it does not even cross the knee (see the image below).
As a result, the medial femoral condyle and the medial plateau of the tibia are subjected to pathologic loading. The Heuter-Volkmann effect will compress the physis and the cartilaginous anlage of these structures and inhibit the normal ossification of the epiphysis. The lateral collateral ligaments are stretched, sometimes beyond their compliance, permitting the characteristic lateral thrust of the knees during gait.
When the mechanical axis deviates into or beyond the medial quadrant of the knee, regardless of the etiology, a number of clinical problems may ensue. Lateral ligamentous strain may be associated with recurrent knee pain, lateral thrust, in toeing, and the evolution of a waddling gait.
The natural history of untreated genu varum is not benign. During the adult years, premature and eccentric stress on the knee may result in medial meniscal tears, tibiofemoral subluxation, articular cartilage attrition, and arthrosis of the medial compartment of the knee. Nonoperative management that relies on shoe modification, physical therapy, and so-called Forrest Gump bracing is of no proven value.
The recognized etiologies for genu varum include the following:
Regardless of the etiology of pathologic genu varum and regardless of the patient’s age, surgical correction of significant and symptomatic malalignment is warranted.
Physiologic genu varum, defined as occurring in children younger than 2 years, is exceedingly common but is self-correcting. In contrast, pathologic genu varum, which is due to a variety of conditions, is much less prevalent, especially with increasing age. Among the known causes are tibia vara (Blount disease), rickets, and skeletal dysplasias. The collective frequency of these conditions is not specifically known, but they are common triggers for pediatric orthopedic referral.
In countries where malnutrition is widespread and access to medical care is limited, the overall incidence of genu varum is undoubtedly higher. Whereas polio has been largely eradicated, other infectious diseases and mistreated (or untreated) traumatic injuries make physeal damage a frequent cause of progressive and disabling clinical deformity.
Likewise, untreated congenital anomalies, genetic disorders, metabolic conditions, and rheumatologic diseases may all cause progressive genu varum. Finally, in any country, one may encounter iatrogenic postoperative genu varum.
The outcome of guided growth for genu varum is dependent on patient selection and timing. As noted earlier, this technique is contraindicated for physiologic genu varum and will be of no benefit after skeletal maturity has been attained. At least 6 (and preferably 12) months of predicted growth is needed to derive any benefit.
For the remainder of patients, regardless of age or diagnosis, guided growth holds promise for complete correction of the deformity and may reduce or eliminate the need for more invasive osteotomies. For specific endocrinologic conditions, concomitant medical management is required.
The parents must have a vested interest in the success of the procedure and must understand that although the incisions are small and the correction gradual, the onus is on them to return for follow-up appointments at the specified intervals (typically every 3 months while the implants are in place).
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Peter M Stevens, MD Professor, Director of Pediatric Orthopedic Fellowship Program, Department of Orthopedics, University of Utah School of Medicine
Peter M Stevens, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Orthopaedic Surgeons, American Orthopaedic Association, Pediatric Orthopaedic Society of North America
Disclosure: Received royalty from Orthofix Inc for independent contractor; Received royalty from Orthopediatrics, Inc for independent contractor; Received honoraria from Orthopediatrics, Inc for speaking and teaching. for: Orthodox, Orthopediatrics.
Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Received salary from Medscape for employment. for: Medscape.
Thomas M DeBerardino, MD Orthopedic Surgeon, The San Antonio Orthopaedic Group; Professor of Orthopedic Surgery, Baylor College of Medicine as Co-Director, Combined Baylor College of Medicine-The San Antonio Orthopaedic Group, Texas Sports Medicine Fellowship; Medical Director, Burkhart Research Institute for Orthopaedics (BRIO) of the San Antonio Orthopaedic Group; Consulting Surgeon, Sports Medicine, Arthroscopy and Reconstruction of the Knee, Hip and Shoulder
Thomas M DeBerardino, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Association, American Orthopaedic Society for Sports Medicine, Arthroscopy Association of North America, Herodicus Society, International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine
Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Arthrex, Inc.; MTF; Aesculap; The Foundry, Cotera; ABMT; Conmed; <br/>Received research grant from: Histogenics; Cotera; Arthrex.
Jeffrey D Thomson, MD Professor of Orthopedic Surgery, University of Connecticut School of Medicine; Director of Orthopedic Surgery, Connecticut Children’s Medical Center; Vice President of Medical Staff, Connecticut Children’s Medical Center
Disclosure: Nothing to disclose.
Pediatric Genu Varum
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