Derek T Cawley1,2, Louis Boissiere3, Caglar Yilgor4, Daniel Larrieu3, Takashi Fujishiro3,5, David Kieser3,6, Ahmet Alanay4, Frank Kleinstück7, Francisco Sánchez Pérez-Grueso8, Ferran Pellisé9, Ibrahim Obeid3. 1. Institut de la Colonne Vertébrale, Spine Unit 1, Bordeaux University Hospital, Bordeaux, France. derekcawley@hotmail.com. 2. Mater Private Hospital, Eccles St, Dublin 1, Republic of Ireland. derekcawley@hotmail.com. 3. Institut de la Colonne Vertébrale, Spine Unit 1, Bordeaux University Hospital, Bordeaux, France. 4. Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Turkey. 5. Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Japan. 6. Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago Christchurch, Christchurch, New Zealand. 7. Spine Center, Schulthess Klinik, Zurich, Switzerland. 8. Spine Surgery Unit, Hospital Universitario La Paz, Madrid, Spain. 9. Spine Surgery Unit, University Hospital Vall d'Hebron, Barcelona, Spain.
Abstract
PURPOSE: A normal sagittal vertical axis (SVA) after spinal deformity correction can yield mechanical complications of up to 30%. Post-operative compensatory pelvic orientation can produce a normal SVA. We assess relative pelvic version (RPV), an individualised measure, for persistent post-operative compensatory measures. METHODS: Adult spinal deformity (ASD) patients who were treated operatively, with a normal SVA (< ± 50 mm) at 6-week follow-up were included, who were then followed-up after 2 years. These only included patients with fusion of > 4 vertebrae extending to L5 or below. Six-week subgroups were made regarding pelvis orientation, relative pelvic version (RPV: anteversion, aligned, moderate or severe retroversion) with analysis of patient-related outcome measures (PROMs), complications and spino-pelvic sagittal parameters. RESULTS: At 6 weeks, 140 patients met the inclusion criteria, 5 (3.6%) patients had anteversion, 59 (42.1%) were aligned, 60 (42.9%) had moderate retroversion and 16 (11.4%) patients had severe retroversion. Follow-up after 2 years demonstrated increased RPV in all groups except the severe RPV group who were more likely to develop SVA > 50 mm. Complications occurred in all groups. Significant 2-year differences were observed between moderate and severe RPV for back pain and PROMs but not between other RPV groups. CONCLUSION: Adult spinal deformity patients with a normal SVA after spino-pelvic instrumentation carry a significant risk of retroversion progression post-operatively, followed by increased positive sagittal balance. Relative pelvic version (RPV) measurements when categorised into anteversion, aligned, moderate retroversion and severe retroversion at 6 weeks were predictive of PROMs at 2 years.
PURPOSE: A normal sagittal vertical axis (SVA) after spinal deformity correction can yield mechanical complications of up to 30%. Post-operative compensatory pelvic orientation can produce a normal SVA. We assess relative pelvic version (RPV), an individualised measure, for persistent post-operative compensatory measures. METHODS: Adult spinal deformity (ASD) patients who were treated operatively, with a normal SVA (< ± 50 mm) at 6-week follow-up were included, who were then followed-up after 2 years. These only included patients with fusion of > 4 vertebrae extending to L5 or below. Six-week subgroups were made regarding pelvis orientation, relative pelvic version (RPV: anteversion, aligned, moderate or severe retroversion) with analysis of patient-related outcome measures (PROMs), complications and spino-pelvic sagittal parameters. RESULTS: At 6 weeks, 140 patients met the inclusion criteria, 5 (3.6%) patients had anteversion, 59 (42.1%) were aligned, 60 (42.9%) had moderate retroversion and 16 (11.4%) patients had severe retroversion. Follow-up after 2 years demonstrated increased RPV in all groups except the severe RPV group who were more likely to develop SVA > 50 mm. Complications occurred in all groups. Significant 2-year differences were observed between moderate and severe RPV for back pain and PROMs but not between other RPV groups. CONCLUSION: Adult spinal deformitypatients with a normal SVA after spino-pelvic instrumentation carry a significant risk of retroversion progression post-operatively, followed by increased positive sagittal balance. Relative pelvic version (RPV) measurements when categorised into anteversion, aligned, moderate retroversion and severe retroversion at 6 weeks were predictive of PROMs at 2 years.