RESULTS: Post-operative improvements were reported for each operation across each substratified outcome measure except general health. Lumbar foraminotomy patients reported the worst outcomes in every domain. CONCLUSIONS: Changes in PROMs vary depending not only on the pre-operative health status, but also on the type of operation carried out. This suggests some procedures may be more effective when considering QALYs, and may lead to limited resources being targeted at those proce- dures that have enhanced PROMs. CONFLICTS OF INTEREST: None. FUNDING SOURCES: None. http://dx.doi.org/10.1016/j.spinee.2014.12.129 Magnetic growing rods in paediatric deformity patients: are they MRI compatible? An in-vitro study Henry Budd, Michael Hutton, Oliver Stokes, Andrew Clarke, John Fulford, Jude Meakin; Royal Devon and Exeter Hospital, Barrack Road, Exeter EX2 5DW BACKGROUND CONTEXT: Adjustable growing rods that elongate within an external magnetic field have revolutionised the management of early-onset paediatric deformity. This patient group includes those with underlying neuromuscular conditions that may require further MR imaging of the neuroaxis. This is currently contraindicated due to the rare earth magnet housed within the rod. PURPOSE: We have investigated the behaviour of the MAGEC (Ellipse Technology) rod to determine whether MRI adversely affects the proper- ties of the rod or causes any detrimental consequences including elonga- tion, shortening, heating or significant artefact to outline implications for this patient group. STUDY DESIGN/SETTING: In-vitro analysis. METHODS: We conducted an in-vitro experiment using MAGEC rods secured in an MRI compatible restraint system using a 1.5T Phillips MRI. Repeated gradient echo multi-scan sequence MRI of the neuroaxis was performed assessing force exerted, elongation, rod properties post- imaging and temperature changes. We used a phantom model to evaluate the amount of artefact induced. RESULTS: During repeated MRI the MAGEC rod elongation mechanism was not triggered. The ability of the rods to lengthen after MRI was not enhanced or impaired and no significant heating effect was demonstrated. The assessment of imaging with a phantom model did reveal a significant degree of artefact up to 30cm and therefore only MRI of the head and cer- vical spine could be interpreted. CONCLUSIONS: This study has demonstrated that there are no detri- mental effects of MRI on the MAGEC rod while the degree of artefact demonstrated implies only imaging of the head and cervical spines will be interpreted with rods in-situ. CONFLICTS OF INTEREST: None. FUNDING SOURCES: None. http://dx.doi.org/10.1016/j.spinee.2014.12.130 The L1 incidence angle - a novel and reliable measure for lumbo- sacral alignment Dominque Rothenfluh, Praveen Inaparthy, Dennis Dominguez, Jean Carlos Queruz, Jeremy Reynolds; Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Trust, Oxford OX3 7HE BACKGROUND CONTEXT: Lumbo-sacral malalignment as described by pelvic incidence-lumbar lordosis (DPILL) mismatch has been linked to disability, higher shear stress and increased risk for adjacent segment disease. PURPOSE: The present study describes the L1 incidence angle which is a simple measure geometrically equal and more accurate than PILL mismatch. STUDY DESIGN/SETTING: Retrospective. METHODS: The L1 incidence angle (L1IA) is defined by a line perpen- dicular to the L1 endplate bisecting the bi-coxo-femoral axis and a line connecting the midpoint of the bi-coxo-femoral axis to the midpoint of the sacral plateau. On 60 standing radiographs of the whole spine, DPILL and L1IA were measured by two raters. The intra- and inter-rater reliability of the L1IA compared to conventional measurement of PI and LL were assessed using Pearson’s correlation and the limits of agreement according to Bland-Alt- man’s analysis using the R statistics package. RESULTS: The average values for DPILL and L1IA measured were -4.63616.5  and -3.66615.1  respectively for rater 1 and -2.33615.3 and -2.27615.8 for rater 2. Pearson’s R was 0.977 (p !0.001) for intra- rater reliability and 0.844 (p !0.001) for inter-rater reliability indicating a strong to good correlation. The Bland-Altman analysis revealed intra- rater limits of agreement between DPILL and L1IA of þ3.3  to -3.5  . The inter-rater limits of agreement for PILL were between þ12.5  and -15.5  and for L1IA between 7.3  and -8.3  . CONCLUSIONS: As per our results, the inter-rater variability seems to be bigger for DPILL than L1IA. L1IA shows a higher measurement accu- racy of 67.5  compared to DPILL. L1IA is therefore a reliable method for initially assessing the degenerative lumbar spine. CONFLICTS OF INTEREST: None. FUNDING SOURCES: None. http://dx.doi.org/10.1016/j.spinee.2014.12.131 Sagittal balance correction using anterior only motion preserving hybrid construct Eyal Behrbalk, Ofir Uri, Peter Rehousek, Bronek Boszczyk; The Centre for Spinal Studies and Surgery, Queen’s Medical Centre BACKGROUND CONTEXT: Sagittal balance (SB) is the most important factor effecting life quality in adults with degenerative spine deformity. Surgi- cal correction of sagittal imbalance resulting from degenerative disc disease remains challenging. Current methods of SB correction are based on posterior osteotomies and instrumented fusion, unfortunately, with high complication rate. This study presents an alternative method for SB correction by recon- structing the anterior column height using ALIF and TDR implants potentially reducing the hardware failure, wound infection and patient’s height reduction associate with posterior approaches while preserving lumbar spine motion. PURPOSE: This study presents an alternative method for SB correction by reconstructing the anterior column height using ALIF and TDR im- plants potentially reducing the hardware failure, wound infection and pa- tient’s height reduction associate with posterior approaches while preserving lumbar spine motion. STUDY DESIGN/SETTING: Case series. PATIENT SAMPLE: 5 patients OUTCOME MEASURES: Radiographic outcome (SB, Pelvic Incidence- [PI], lumbar lordosis-[LL] and thoracic kyphosis-[TK]) were reviewed ret- rospectively at a mean of 35610 months follow-up. METHODS: Five women (mean age 6464 years) with degenerative spine deformity and symptomatic sagittal imbalance were operated on using an anterior-only approach. Four of them underwent retroperitoneal approach performing ALIF at L4-5, L5-S1 and TDR at L2-3, L3-4 and one under- went trans-peritoneal approach with visceral rotation performing ALIF at T12-L1, L1-2, L4-5 and TDR at L2-3 and L3-4. RESULTS: At the latest postoperative follow-up the SB was corrected from 71.2636 mm to 6.7630 mm (p50.023) – balanced spine. LL in- creased from minus 10.2616 degrees (kyphotic LL) to 40.7618 degrees (p ! 0.001) to match the PI. TK was secondarily increased from 23.7610 degrees to 40.5614.3 degrees (p50.022). No hardware failure, infection, neurological injury noted. CONCLUSIONS: These radiographic results suggest that anterior-only approach with hybrid construct of ALIF and TDR may offer a safe and ef- fective method of restoring SB and anterior column height while 82S Proceedings of the BASS 2015 Bath Meeting / The Spine Journal 15 (2015) 50S–85S