N Bocahut1, E Audureau2, A Poignard3, J Delambre3, S Queinnec3, C-H Flouzat Lachaniette2, J Allain3. 1. Hôpital universitaire Henri-Mondor, 51, avenue du Maréchal-de-Lattre-de-Tassigny, 94000 Créteil, France. Electronic address: nicolas.bocahut@aphp.fr. 2. Hôpital universitaire Henri-Mondor, 51, avenue du Maréchal-de-Lattre-de-Tassigny, 94000 Créteil, France. 3. Institut Parisien-du-Dos, Clinique Geoffroy-Saint-Hilaire, Paris, France.
Abstract
BACKGROUND: Few data are available on the occurrence after stand-alone lateral lumbar interbody fusion (LLIF) of implant subsidence, whose definition and incidence vary across studies. The primary objective of this work was to determine the incidence of subsidence 1 year postoperatively, using an original measurement method, whose validity was first assessed. The secondary objective was to assess the clinical impact of subsidence. HYPOTHESIS: Implant subsidence after stand-alone LLIF is a common complication that can adversely affect clinical outcomes. MATERIAL AND METHODS: Of 69 included patients who underwent stand-alone LLIF, 67 (97%) were re-evaluated at least 1 year later. Furthermore, 63 (91%) patients had two available computed tomography (CT) scans for assessing subsidence, one performed immediately after surgery and the other 1 year later. Reproducibility of the original measurement method was assessed in a preliminary study. Subsidence was defined as at least 4mm loss of fused space height. RESULTS: The incidence of subsidence was 32% (20 patients). Subsidence was global in 7 (11%) patients and partial in 13 (21%) patients. Mean loss of height was 5.5±1.5mm. Subsidence predominated anteriorly in 50% of cases. The lordotic curvature of the fused segment was altered in 50% of patients, by a mean of 8°±3°. Fusion was achieved in 67/69 (97%) patients. The Oswestry score and visual analogue scale scores for low-back and nerve-root pain were significantly improved after 1 year in the overall population and in the groups with and without subsidence. DISCUSSION: Reproducibility of our measurement method was found to be excellent. Subsidence was common but without significant clinical effects after 1 year. Nevertheless, subsidence can be associated with pain and can result in loss of lumbar lordosis, which is a potential risk factor for degenerative disease of the adjacent segments. A score for predicting the risk of subsidence will now be developed by our group as a tool for improving patient selection to stand-alone LLIF. LEVEL OF EVIDENCE: IV, retrospective cohort study.
BACKGROUND: Few data are available on the occurrence after stand-alone lateral lumbar interbody fusion (LLIF) of implant subsidence, whose definition and incidence vary across studies. The primary objective of this work was to determine the incidence of subsidence 1 year postoperatively, using an original measurement method, whose validity was first assessed. The secondary objective was to assess the clinical impact of subsidence. HYPOTHESIS: Implant subsidence after stand-alone LLIF is a common complication that can adversely affect clinical outcomes. MATERIAL AND METHODS: Of 69 included patients who underwent stand-alone LLIF, 67 (97%) were re-evaluated at least 1 year later. Furthermore, 63 (91%) patients had two available computed tomography (CT) scans for assessing subsidence, one performed immediately after surgery and the other 1 year later. Reproducibility of the original measurement method was assessed in a preliminary study. Subsidence was defined as at least 4mm loss of fused space height. RESULTS: The incidence of subsidence was 32% (20 patients). Subsidence was global in 7 (11%) patients and partial in 13 (21%) patients. Mean loss of height was 5.5±1.5mm. Subsidence predominated anteriorly in 50% of cases. The lordotic curvature of the fused segment was altered in 50% of patients, by a mean of 8°±3°. Fusion was achieved in 67/69 (97%) patients. The Oswestry score and visual analogue scale scores for low-back and nerve-root pain were significantly improved after 1 year in the overall population and in the groups with and without subsidence. DISCUSSION: Reproducibility of our measurement method was found to be excellent. Subsidence was common but without significant clinical effects after 1 year. Nevertheless, subsidence can be associated with pain and can result in loss of lumbar lordosis, which is a potential risk factor for degenerative disease of the adjacent segments. A score for predicting the risk of subsidence will now be developed by our group as a tool for improving patient selection to stand-alone LLIF. LEVEL OF EVIDENCE: IV, retrospective cohort study.
Authors: Dominik Adl Amini; Manuel Moser; Lisa Oezel; Jiaqi Zhu; Jennifer Shue; Andrew A Sama; Frank P Cammisa; Federico P Girardi; Alexander P Hughes Journal: Eur Spine J Date: 2021-10-28 Impact factor: 2.721