O0813 Oct.3: 3:47pm - Depression of the Medial Tibial Plateau in Infantile Blount Disease – Can Pathologic Bony Changes be Reversed with Guided Growth Treatment?

Background/Purpose: Studies have reported success in correcting the mechanical axis of the lower extremity in Infantile Blount disease using guided growth (GG) tension band plating technique, but it is not known if GG can affect improvement of the bony deformity seen at the proximal tibia. This study assesses whether the pathologic morphology at the proximal tibia can improve or resolve with guided growth treatment.

Methods: We performed a retrospective review of patients with a diagnosis of Infantile Blount disease who underwent GG surgery between 2010 and 2018 at one of two institutions. Severity of deformity of the medial tibial plateau was determined based on the Langenskiold classification and lower extremity alignment was evaluated by assessing mechanical axis deviation (MAD) before surgery, at minimum of 1 year after initial surgery or at removal of hardware (ROH), and at most recent follow-up (F/U).

Results: A total of 22 limbs in 14 children who underwent GG surgery were evaluated. Patients were on average 6.1 +/-2.3 yo at surgery and average length of implant retention was 1.6 +/-0.5 years. Average F/U was 3.4 +/-1.7 years. Langenskiold classification ranged from 1 to 5 pre-operatively with 13/22 (59%) limbs rated 3 and higher. The Langenskiold stage had improved in 14/22 (64%) limbs at 1 year of GG or ROH and in 15/17 limbs (88%) at most recent F/U. Langenskiold changes completely resolved in 7/17 (41%) limbs at F/U. MAD improved from 36.1 +/-16.5mm to 3.5 +/-25.15mm at 1 yr after GG or ROH and 15.3 +/-25.2mm at F/U. Pre-operatively, the MAD showed pathologic varus in all limbs but normalized in 12/20 limbs (60%) after 1 yr of GG or at ROH and 8/17 limbs (47%) at F/U. One limb of a 2.6 yo and 1 limb of a 4.3 yo had no improvement in Langenskiold classification even though the MAD corrected after 1 year of GG treatment. One limb of a 7 yo progressed from Langenskiold stage 5 to stage 6 after 1.15 years of GG. This patient subsequently underwent tibia dome osteotomy and hemiplateau elevation.

Conclusion: This is the first study to demonstrate improvement or resolution of medial proximal tibial deformity in Infantile Blount disease in a majority of patients who underwent tension band plating, even when advanced deformity of the proximal tibia was present. Guided growth surgery for Infantile Blount disease may be a better first-line treatment option than more invasive surgery such as osteotomy and/or hemiplateau elevation.