Pseudarthrosis Daniel CHOPIN Pôle Neuroscience et appareil Locomoteur Clinique de neurochirurgie Unité Rachis Neuro-Orthopédique Hopital Roger Salengro Université de Lille VII convention of the Russian Association of Spinal jsurgeons in conjonction with SRS WW course 27-28 May 2016

Bone Union Healing process is a multifactorial process including biological and mechanical factors. No clear cut definition of non union: documented failure of solid union after 1 year New technologies (instrumentations, graft expenders, osteoinductive substances) have reduced dramatically the rate of non-union in pediatric and young adults spinal deformity surgery.

Pseudarthrosis BUT Pseudarthrosis remain the major cause of reintervention in adult spinal deformity surgery 17% to 23,3% D.B Pateder et all Spine 2006 Y.Kim et all Spine 2006 M.Kelly et all Spine 2013 H. Koller et all Eur Spîne J 2015 VII convention of the Russian association of Spinal surgeons in conjonction with SRS WW course 27-28 May 2016

Clinical symptoms After post-operative improvement: Axial Pain Leg pain referal Recurence of deformity Increasing sagittal/ coronal imbalance around 1y after surgery. But may be completely asymptomatique for many years.(Detection between 1 and 5y, up to 10y!)

Radiological Plain Xrays Lucency around implants Rod fracture : non-union in ½ and ¾ of symptomatic patient C.Barton et al Scoliosis 2015 Hook-screw pull-off Loss of correction Imbalance VII convention of the Russian association of Spinal surgeons in conjonction with SRS WW course 27-28 May 2016

56y PO 1year PO

Radiological CT scan with sagittal and coronal reconstruction. Radionucleotide scans VII convention of the Russian association of Spinal surgeons in conjonction with SRS WW course 27-28 May 2016

Risk Factors Age >55-65y Comorbodities Long fusion >12 v Osteotomies (PSO,VCR) Fusion to the Pelvis Thoraco-lumbar kyphosis > 20° Sagittal imbalance VII convention of the Russian association of Spinal surgeons in conjonction with SRS WW course 27-28 May 2016

Fusion to pelvis 35 to 44% of all pseudarthrosis Prevention Sacro pelvic fixation with iliac screws lower by 50% the non union rate compare to isolated sacral screw (Kim spine 2006). Anterior structural support of any high disc at LS junction VII convention of the Russian association of Spinal surgeons in conjonction with SRS WW course 27-28 May 2016

Iliac Screw Fixation D. Chopin 1987 Biomechanical study: McCord 1992

55y 58y 3y po extension to S1

Sagittal Balance Increasing risk with greater preop imbalance Increase risk with post-op imbalance C7 SVA >5cm Small post-op Lumbar Lordosis (an increase by 35° of LL reduce the risk of non-union by 50%) PT Kim YJ Spine 2006 :positive sagittal balance>5cm at 8 weeks D.Pateder Spine 2006 TL Kyphosis >20°, greater sagittal imbalance. H. Koller Eur. Spine J 2015 VII convention of the Russian association of Spinal surgeons in conjonction with SRS WW course 27-28 May 2016

3 column Spinal Osteomies 10,6% symptomatic non-union 61,1% PSO level 3 to 4 rods construct 2RC 17% rod breakage half requiring revision 4RC 3% partial implant failure .no revision Anterior column support of adjacent high discs S-J Hyun et al spine 2014 D. Dickson et al Spine 2014 VII convention of the Russian association of Spinal surgeons in conjonction with SRS WW course 27-28 May 2016

Biology Meticulous decortication: good vascular environment Autogenous Iliac Crest Bone Graft: gold standard, osteogenic, osteoconductive, osteoinductive Osteoconductive substances (ceramics, allograft) Osteoinductive: bone marrow aspirate R. Ajiboye et al Eur Spine J 2015 rhBMP: VII convention of the Russian association of Spinal surgeons in conjonction with SRS WW course 27-28 May 2016

BMP K Guppy et al Spine 2014 Ra’K Rahman et al Spine 2013 9425 spine fusions: no difference with or without BMP Ra’K Rahman et al Spine 2013 Long fusion to pelvis :fusion rate at L5S1 no difference between rhBMP alone or associated TLIF. J. Paul et al Spine 2016 Long fusions for ASD reoperation for non union: 5% with BMP 33,9% without BMP

Management Rod breakage asymptomatic, good balance , distant from index surgery: observation. Symptomatic, implant failure, imbalance, loss of correction: Revision of all the fusion mass (multilevel pseudarthrosis) Restoration of balance including major osteotomies Solid pelvic fixation, multilevel Pedicular Screws BMP, bone extenders Anterior support of high open discs

69 years

Conclusions Pseudarthrosis is the most frequent cause of reoperation Despite third generation instrumentations, bone extenders and osteoinductors, the rate is still high. Selection of patients, restoration of coronal and sagittal balance are of first importance as well as mechanical and biological ressources. More work must be done to improve the rate of fusion in patients at risk. VII convention of the Russian association of Spinal surgeons in conjonction with SRS WW course 27-28 May 2016