title: Sagittal alignment in lumbosacral fusion: relations between radiological parameters and pain.
abstract: The objective of this study was to conduct a radiological analysis of posture before and after lumbosacral fusion to evaluate the influence of spinal alignment on the occurrence and pattern of post surgical pain. The study included 81 patients, of whom 51 had a history of previous low back surgery. We excluded patients with suspected or confirmed nonunion. In the fusion group, the 27 patients who were pain free after the procedure were compared to the 54 patients with residual pain. Thirty patients had pain only or primarily when they were standing immobile, 18 when they were sitting immobile, and six in both positions. Measurements were done on full-length lateral radiographs of the spine, with the patient standing according to Duval Beaupère criteria. The subgroup with postfusion pain was characterized at baseline by a more vertical sacrum with less sacral tilt (ST) (P < 0.0062) and more pelvic tilt (PT) (P < 0.0160). PT at last follow-up (PT fu) correlated with the presence of postfusion pain (NP: P = 0.0003). In the patients with postfusion pain, PT was almost twice the normal value. ST at last follow-up (ST fu) in the standing position was also correlated with the presence of postfusion pain (P < 0.0001) indicating that the sacrum remained abnormally vertical in the subjects with postfusion pain. Using logistic regression, the only prognostic factor for residual pain at last follow-up was ST fu. Both at pre-operative evaluation and at last follow-up, patients with pain in the standing position or in both the standing and sitting positions were characterized at pre-operative status by a more vertical sacrum with less sacral tilt. The results of this study indicate that, achieving a strong fusion should not be the only goal. Appropriate position of the fused vertebrae is also of paramount importance to minimize muscle work during posture maintenance. The main risk is failing to correct or to causing excessive pelvic retroversion with a vertical sacrum leading to a sagittal alignment that replicates the sitting position. This situation is often accompanied by loss of lumbar lordosis and adversely affects stiff or degenerative hips.
authors.affiliation: Service de Chirurgie Orthopédique et Traumatologique, Hôpital Pitie-Salpetrière 83, Paris, France.
authors.forename: J Y
authors.initials: JY
authors.lastname: Lazennec
authors.forename: S
authors.initials: S
authors.lastname: Ramaré
authors.forename: N
authors.initials: N
authors.lastname: Arafati
authors.forename: C G
authors.initials: CG
authors.lastname: Laudet
authors.forename: M
authors.initials: M
authors.lastname: Gorin
authors.forename: B
authors.initials: B
authors.lastname: Roger
authors.forename: S
authors.initials: S
authors.lastname: Hansen
authors.forename: G
authors.initials: G
authors.lastname: Saillant
authors.forename: L
authors.initials: L
authors.lastname: Maurs
authors.forename: R
authors.initials: R
authors.lastname: Trabelsi
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis; D011187:Posture; D011237:Predictive Value of Tests; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012447:Sacrum / Q000000981:diagnostic imaging* / Q000601:surgery; D013123:Spinal Fusion