Radiographic outcomes of anterior column realignment for adult sagittal plane deformity: a multicenter analysis

Purpose Anterior column reconstruction (ACR) is a minimally invasive technique for the treatment of sagittal plane deformity. ACR uses a lateral transpsoas approach with ALL release and the application of an interbody device to achieve correction. Here, we present 1-year radiographic results from a multicenter study of adult spinal deformity (ASD) patients. Methods A multicenter database was queried from 2005 to 2013 for ASD patients treated with ACR. Demographics, surgical data, and radiographic measurements were collected and retrospectively analyzed. Radiographic time points included preoperative (pre-op), postoperative (postop; first visit prior to 3 months), and last follow-up (last FU; minimum of 1 year). Sagittal radiographic measurements included regional lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), T1 spinopelvic inclination (T1SPi), and segmental lordosis (disc angle). Results Mean patient age was 67.4 years (range 46.5-80.0) and 11 patients (32.4 %) were male. Twenty patients (58.8 %) had previous lumbar surgery. All patients had a minimal of one-level ACR with ALL release (mean 1.7; range 1-4). Mean number of lateral interbody fusion (LLIF) levels without ALL release per patient was 0.7 (range 0-3). Thirty-three patients (97.1 %) received supplemental posterior fixation and 1 patient (2.9 %) had lateral fixation only. In 26 patients (76.5 %), supplemental posterior fixation was performed using an open approach, and 7 patients (20.6 %) were treated with percutaneous placement. Mean of number of levels fused was 7.1 (range 2-16). There was a significant improvement in LL (p < 0.001), PI-LL mismatch (p < 0.001), and PT (p = 0.03) from pre-op to post-op, and pre-op to last FU. There was no change in T1SPi, SS, or PI. Segmental lordosis improved at ACR levels from mean of -2.2 degrees pre-op to -16.0 degrees post-op (p<0.01) and -16.3 degrees at last FU (p\ 0.001). The addition of posterior column osteotomy increased the change in segmental lordosis with ACR by 72.7 % (p<0.001). LLIF without ALL release led to significant improvement in segmental lordosis from pre-op (-2.4 degrees) to post-op (-7.1 degrees; p<0.01) but not from pre-op to last FU (-5.7 degrees; p = 0.06). Conclusion ACR successfully restores lumbar lordosis in ASD patients with sagittal imbalance. ACR results in greater segmental correction than is achieved with LLIF alone. Supplementing with posterior osteotomies allows for even greater correction. The ability to achieve the desired radiographic goals is expected to improve as technical nuances are refined and patient selection is optimized.