Review Question - QID 1298

This question highlights the indications for selective anterior fusion of a thoracolumbar or lumbar curve while leaving the associated thoracic curve uncorrected. This patient needs a spine fusion because her major curve measures greater than 40 degrees (<20 observe, 20-40 brace) and it will progress without fusion. Selective anterior fusion of a major curve has the advantage over posterior fusion of sparing motion segments. However, anterior fusion can be associated with kyphosis over the instrumented levels and higher pseudarthrosis rates when compared to PSF. This patient has a 55 degree thoracolumbar curve. The question tells you the there is a compensatory thoracic curve of 30 deg that corrects to 10 degrees. She is 8 mo postmenarchal and therefore past her major growth spurt, though she does have some growth remaining. The two citations are from Lenke and collaborators. The 2003 paper identified the best predictors of success in patients who underwent selective anterior fusion of thoracolumbar (TL) or lumbar (L) curves while leaving the associated thoracic curve uncorrected. These useful predictors included TL/L:T Cobb ratio was 1.25 or greater (42 out of 44 pts) and if the triradiate cartilage was closed (42 of 43 pts). The 2001 paper is a prospective outcome study in which 90 pts underwent anterior fusion for thoracic or thoracolumbar/lumbar scoliosis using intradiscal structural (Harms) cages placed below T12 with a single solid anterior rod. The rate of pseudarthrosis was 5.5%. The reoperation rate was 3.3% with posterior fusion required in 3 of 5 pseudos. Pseudarthrosis was associated with smoking, weight >70 kg, and hyperkyposis >40 deg at T5-T12. Given this data, we would predict that the patient would do well with an anterior fusion of the thoracolumbar curve only (answer 3)—provided that she doesn’t smoke or weighs more than 70 kg.