eMedicine Specialties > Orthopedic Surgery > Pediatrics

Genu Valgum, Pediatrics: Treatment

Author: Peter M Stevens, MD, Professor, Director of Pediatric Orthopedic Fellowship Program, Department of Orthopedics, University of Utah School of Medicine
Coauthor(s): Michael C Holmstrom, MD, Consulting Surgeon, Department of Orthopedics, The Orthopedic Specialty Hospital (TOSH)
Contributor Information and Disclosures

Updated: Jul 19, 2007

Treatment

Medical Therapy

For the child with specific and identifiable bone dysplasia, medical treatment may have an important role, influencing the outcome. For example, the child with vitamin D–resistant rickets should be on appropriate medication to optimize bone formation and mineralization. Likewise, children with osteogenesis imperfecta may benefit from treatment with bisphosphonates to increase bone density and decrease the risk of fractures. Recognizing the need for holistic care, even optimal medical management does not correct preexisting genu valgum. However, treatment may slow the progression of the condition and prevent recurrence. Bracing and physical therapy may provide a temporary reprieve of symptoms, but they do not afford long-term symptomatic relief.

Surgical Therapy

Having concluded that osteotomy should be reserved as a salvage option (or for mature patients), an opportunity arises to safely use guided growth as treatment. Despite the age of the child or the etiology of the valgus, even children with "sick physes" may be well served by the application of an extraperiosteal 2-hole plate at the apex (or apices) of the deformity. The ensuing growth should correct the deformity within an average of 12 months. This is documented with quarterly follow-up evaluations, including full-length radiographs with the legs straight.

When the mechanical axis has been restored to neutral, the implants are removed. Growth should be monitored because if the valgus recurs, guided growth may need to be repeated. The goal is to correct the deformity, which alleviates the pain and gait disturbance and protects the knee throughout the growing years. If this requires repeated, yet minor, intervention, the benefits still outweigh the cost and risks of (sometimes) repeated osteotomies.

Preoperative Details

The importance of recognizing the difference between physiologic and pathologic valgus and reserving treatment for the latter cannot be overemphasized. Consider the symptoms and document the degree and progression of genu valgum before considering surgical intervention. Apart from encroaching skeletal maturity, time is not of the essence here. The patient's height should be recorded, along with the limb lengths and the IMD, measured with the patient standing with his or her knees touching.

Preoperative planning should be undertaken using the full-length radiographs to select the optimal solution, predict the outcome, and convey this information to the family. When considering guided growth, it is prudent to address any significant valgus deformity at its primary site(s) to preserve a horizontal knee axis while neutralizing the mechanical axis so that it bisects the knee. For idiopathic genu valgum, the distal femur is the preferred site of plate application, while for various skeletal dysplasias and metabolic problems, both femur and tibia may be appropriate plating sites. Only one plate is needed per level, serving as a tension band (compression of the physis is not the principle here).

Remember to evaluate sagittal alignment of the knee; these deformities may be addressed simultaneously. For example, a flexion/valgus or oblique-plane deformity of the knee may be resolved by anteromedial femoral plate application; likewise, flexion/varus warrants a single anterolateral plate. For fixed-knee flexion deformities (not the topic of this article), 2 plates are used; one is just lateral to the sulcus and one is medial. This permits unobstructed gliding of the patella. Length discrepancies may be corrected by modular guided growth—adding or removing plates as the child grows, so that equal limb lengths are achieved at maturity, without having to resort to distraction osteogenesis.

Intraoperative Details

The patient should be supine on a radiolucent operating table. An image intensifier is used to localize the physes of the distal femur, proximal tibia, or both.

For femoral plating, the medial incision is centered over the adductor tubercle. An oblique incision is made in the vastus medialis fascia, mobilizing this muscle and retracting it anteriorly. The periosteum is left undisturbed to avoid premature physeal closure. A needle is inserted into the medial physis. A titanium 8-plate (Orthofix; McKinney, Tex) is placed over the needle, and the 8-plate is centered on the physis. The extraperiosteal plate is then secured to the bone by first introducing the 1.6-mm. guide pins, epiphyseal first, then metaphyseal. After starter holes are drilled to a depth of 5 mm with the cannulated 3.2-mm drill, the plate is securely attached with 2 of the 4.5-mm. cannulated, self-tapping screws. While the screws do not need to be parallel, they should not violate the physis or the joint. In the sagittal plane, center the plate to avoid an iatrogenic recurvatum (too anterior) deformity.

For the proximal tibia, the medial physis is approached through a separate longitudinal incision and the superficial tibial collateral ligament is split, again leaving the periosteum intact. A needle is inserted, followed by the extraperiosteal 8-plate, which is secured according to the technique described above. The titanium 8-plate (Orthofix; McKinney, Tex) comes in 2 sizes, namely 12 or 16 mm (measured from center hole to center hole). They are both low profile and of equal thickness, with a center hole for the needle to allow for accurate placement.

The screws are titanium, cannulated, and self-tapping; they come in 3 lengths, which are 16 mm (for the ankle, wrist, or elbow), 24 mm (often used for the tibia), and 32 mm (for the femur). The plates and screws are painted and color-coded for ease of identification, but the surgeon may mix and match as dictated by the local anatomy. This is intentionally not a locking plate; the principal is to deflect the physis (tension band) rather than overpower it. Thus, it is a paradigm shift and departure from the traditional stapling methodology.

Postoperative Details

Following the layered closure, the tourniquet is deflated, and a soft compression dressing is applied to the knee. No immobilization is required; immediate weightbearing is encouraged, and progressive activities are permitted as tolerated. This procedure is routinely accomplished on an outpatient basis, and physical therapy is rarely required.

Follow-up

Guided growth mandates periodic follow-up evaluations (typically at 3-mo intervals) so that the rate of correction can be assessed to determine the optimal timing for plate removal. The parents should be instructed in how to monitor the IMD; overcorrection into varus can be averted if parents are educated and involved. When the knees and ankles touch simultaneously (IMD = 0), a full-length radiograph should be obtained to measure the mechanical axis and limb lengths. The plate(s) should be removed when the mechanical axis is neutral and further growth should be monitored. Guided growth may be safely repeated for angular and/or length discrepancies, according to the needs of the individual patient.

Complications

For this meticulous but relatively simple operative procedure, complications are rare. Minimal dissection is involved; therefore, wound-healing problems such as hematoma, infection, or dehiscence are uncommon. If keloid formation is a problem, the scar may be excised at the time of plate removal.

With the switch from staples to the 8-plate, the problems of hardware migration or fatigue have been solved. The screws intentionally diverge with growth; however, this does not require screw exchange. The relatively thin titanium plates conform to the bone and are free to bend with correction (this is rarely observed). Because the bone is not divided, no need exists to wait for healing. This procedure does not place the patient at risk for nonunion, delayed union, compartment syndrome, or neurologic damage, all of which have been reported with osteotomy of the distal femur or proximal tibia/fibula).

The issue of rebound growth remains ill defined. While this was reported with stapling, especially in children younger then 10 years, it seems less common with the plate technique. Perhaps this reflects a different biology; one not applying a rigid construct (multiple staples) to a dynamic physis. The result may reflect a more physiologic response with less propensity for rebound. However, in the event of recurrent deformity, repeat plate application is warranted if rebound growth occurs to the point the mechanical axis drifts into lateral zone 2 or 3. This underscores the need for parental education and periodic follow-up evaluations.

Permanent physeal closure does not occur, provided meticulous care is taken to place (and remove) plates without disturbing the periosteum. In 5 years of plating, including more than 100 children with the full spectrum of diagnoses, this author has yet to observe this complication. Remember that all of these patients would have had 1 or more osteotomies if they had not undergone guided growth.

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