Obesity in Pediatric Orthopaedics
Obesity in Pediatric Orthopaedics
Blount disease is another condition classically associated with obesity. Increased shear and compressive forces across the medial proximal tibial physis are related to increased weight, possible preexisting genu varum and the ''fat thigh'' gait (reviewed in Birch). In addition, decreased vitamin D levels have been associated with increased risk of Blount disease in obese patients. Furthermore, these patients have advanced bone age, which may affect treatment decisions, particularly with respect to guided growth and to overcorrection when substantial growth remains.
With respect to treatment, obese patients are likely at increased risk of implant failure with attempted guided growth. A biomechanical comparison of available instrumentation was performed in an effort to ascertain which available constructs might best resist the increased forces associated with obesity. Results confirmed previous work that solid screws fare better than cannulated screws and that stainless steel is more durable than titanium. Some controversy exists as to the applicability of the study as noted in an editorial by one of the developers of the eight-Plate. Use of guided growth in infantile tibia vara has shown promise for correction, but a high rate of recurrence is noted, as with any treatment for this group. Controversy exists as to whether guided growth is successful in correcting deformity and/or preventing progression of deformity in obese adolescent patients with Blount disease. Given the low morbidity compared with osteotomy, it is still common (including in the author's practice) to use guided growth as an initial treatment or as an adjunctive treatment to prevent recurrence or progression. Guided growth does not correct rotational alignment, however. A recent case report advocated using guided growth to correct the proximal tibial varus, with the addition of a distal tibial derotational osteotomy. The purported advantage is to avoid the potential for complications more common with proximal tibial osteotomy such as loss of fixation or compartment syndrome.
Gradual correction using external fixation is a common method of treatment for both infantile and adolescent tibia vara, particularly in patients with severe deformity. Acceptable realignment can be achieved, even in the severely obese; however, the complication rates are high. Common complications include strut disengagement, pin site irritation, premature fibular consolidation, transient deep peroneal nerve palsy, and soft-tissue impingement by the frame. It should not be anticipated that patients will lose weight subsequent to deformity correction. In fact, most patients undergoing external fixation for Blount disease gain significant weight and longer term follow-up of patients in another study found continued increase in BMI.
Blount Disease
Blount disease is another condition classically associated with obesity. Increased shear and compressive forces across the medial proximal tibial physis are related to increased weight, possible preexisting genu varum and the ''fat thigh'' gait (reviewed in Birch). In addition, decreased vitamin D levels have been associated with increased risk of Blount disease in obese patients. Furthermore, these patients have advanced bone age, which may affect treatment decisions, particularly with respect to guided growth and to overcorrection when substantial growth remains.
With respect to treatment, obese patients are likely at increased risk of implant failure with attempted guided growth. A biomechanical comparison of available instrumentation was performed in an effort to ascertain which available constructs might best resist the increased forces associated with obesity. Results confirmed previous work that solid screws fare better than cannulated screws and that stainless steel is more durable than titanium. Some controversy exists as to the applicability of the study as noted in an editorial by one of the developers of the eight-Plate. Use of guided growth in infantile tibia vara has shown promise for correction, but a high rate of recurrence is noted, as with any treatment for this group. Controversy exists as to whether guided growth is successful in correcting deformity and/or preventing progression of deformity in obese adolescent patients with Blount disease. Given the low morbidity compared with osteotomy, it is still common (including in the author's practice) to use guided growth as an initial treatment or as an adjunctive treatment to prevent recurrence or progression. Guided growth does not correct rotational alignment, however. A recent case report advocated using guided growth to correct the proximal tibial varus, with the addition of a distal tibial derotational osteotomy. The purported advantage is to avoid the potential for complications more common with proximal tibial osteotomy such as loss of fixation or compartment syndrome.
Gradual correction using external fixation is a common method of treatment for both infantile and adolescent tibia vara, particularly in patients with severe deformity. Acceptable realignment can be achieved, even in the severely obese; however, the complication rates are high. Common complications include strut disengagement, pin site irritation, premature fibular consolidation, transient deep peroneal nerve palsy, and soft-tissue impingement by the frame. It should not be anticipated that patients will lose weight subsequent to deformity correction. In fact, most patients undergoing external fixation for Blount disease gain significant weight and longer term follow-up of patients in another study found continued increase in BMI.