Review Question - QID 210162

Out of the patient scenarios listed above, a patient with widened intermalleolar distance and resulting genu valgum would benefit most from guided growth using medial tension band plating. After age 7, the intermalleolar distance should be less than 8cm and valgus alignment should be less than 12 degrees.

Coronal plane angular deformity is a common reason for pediatric orthopaedic consultation. Knowledge of the normal physiological growth process is necessary to plan treatment. Treatment options include observation, bracing, and surgical intervention with guided growth or osteotomy, depending on the patient's age and extent of the deformity. The lower extremity coronal plane profile changes in a predictable pattern beginning with varus at birth until the age of 7-8, which is when a child is expected to achieve their adult alignment. Excessive genu valgum can result in knee pain, difficulty running, and patellar instability. It should be noted that the adult tibiofemoral alignment lies between 4-7 degrees of valgus. Medial tension band plating (TBP), an example of physeal tethering, is an excellent option for correcting angular deformities in the skeletally immature. It allows for continued longitudinal growth with gradual angular correction over time.

Saran et al. reviewed the various techniques available for pediatric lower extremity angular correction using guided growth. Techniques for physeal tethering include TBP (i.e. 8-plates), staples, and screws. Drilling hemiephysiodesis is an option for correcting angular deformity by inducing a physeal bar formation but requires a completed epiphysiodesis upon angular correction and results in a loss of longitudinal growth.

Shabtai and colleagues reviewed the expanded indications for TBP in the correction pediatric deformity. They report that the indications for the utilization of TBP have grown beyond the correction of angular deformity and discuss its limitations. Undercorrection and overcorrection are common problems with guided growth. However, careful preoperative planning and appropriate follow-up can minimize complications and allow for excellent deformity correction with minimal morbidity.

Illustration A shows the typical progression of pediatric lower extremity alignment from varus at birth, maximum valgus at about 4 years of age, and achievement of adult alignment by the age of 8. Illustration B is an example of tension band plating for the correction of genu valgum.

Incorrect Answers
Answer 1: This is an example of Blount's disease which would benefit from lateral based tension band plating, not medial.
Answer 3: At 4 years old, we expect children to be in maximum valgus. 20 degrees is within the physiologic acceptable parameters and observation would, therefore, be appropriate.
Answer 4: This is an acceptable alignment.
Answer 5: This child's genu valgum is large enough to intervene surgically if she is symptomatic. However, at the age of 16, the patient is near skeletal maturity so guided growth would not be the best option for treatment. At this age, she would benefit more from varus producing osteotomies.