In the name of God H. Moin M.D, F. R.C.S Oct. 2009

Epidemiology 30% of lumbar fusion for listhesis & Narrow canal. Varies with sex & race Isthmic more in male and L5-S1 Degenerative more in female and L4-L5 Hereditory:First degree relative 20-70% are involved.

Spondylolisthesis Classification 1- Congenital (Dysplastic) 2- Isthmic 3- Degenerative 4- Traumatic 5- Pathologic 6- Surgical (Iatrogenic)

Diagnostic study Plain X-ray C.T. Isotop scan SPECT: Has advantage to the above but sensitivity more than specificity M.R.I

Risk of Progression 1- Young age (Decreased skeletal maturity) 2- Slip more than 50% 3- ship angle more than 40-50% (up to 10 o normal) 4- Female 5- Dome shaped sacrum 6- Dysplastic lumbo – sacral Junction

Treatment : A- Conservative More in spondylolysis and low grade spondylolisthesis. 1- Bracing for 6 months then weering off 2- Lumbo-Sacral stretching 3- Paraspinal & abdominal muscle stretching and electrical stimulation. 20% Heales and 80% have positive result.

B- Operative 2- Slip more than 50% 3- Slip progression Indications: 1- Uncontrolled pain or symptom 2- Slip more than 50% 3- Slip progression 4- High slip angle (more than 30%) 5- Significant root irritation causing sciatic scoliosis 6- Progressive neurological deficit 7- Hamstring tightness 8- Disability deformity

Risk factors for instability and poor result 1- female sex 2- obesity 3- mobility on preop. Radiography 4- Relatively young age 5- Greater activity 6- Large disc space with herniation and without margical osteophytes 7- Laxity of ligament and facet dimension & orientation 8- Work related injury 9- Smoker 10- Slippage more than 25% (may give pseudoathrosis)

Operations 1- Decompression alone Specially in isolated radiculopathy 70% good result, usually in Grade 1 & 2 high risk of progression specially in children not generally advocated. Exception : Adult with lysis or minimal listhesis without motion on dynamic radiography and with isolated unilateral radiculopathy.

2- Direct pars .repair Young patient with conservative tailure Advantage: preserves the anatomic integrity and motion of the affected segment. 90% good or excellent result, success highly depends on normal adjacent disc. If substantial disc degeneration or segmental instability postero-lateral fusion with or without instrument is the procedure of choice.

3- In situ fusion Usually in children and adult, good results adolescent ( 95%). It dose not improve slip angle . 4- Postero lateral + Inter body fusion with instrument If high grade, slip angle>30o , Trapezoid L5, dome shaped sacrum, and hyperlordosis more than 50%

Instrument advantage 1- Correction of slip angle 2- Increases fusion rate 3- Allowing full neural decompression 4- Lesser nonunion The advantage of instrument in low grade are less evident.

Surgery in degenerative spondylolisthesis 1- Midline decompression and no damage of facets 80% good result. 2- Midline decompression + posterolateral fusion 90% good result. 3- Decompression + instrumentation and posterolateral fusion which improves fusion significantly and maintain reduction 4- Decompression + PLIF

Cage alone least stable construct Cage + posterior instrumentation the most stable with excellent outcome for pain Minimally invasive spine surgery is being studied Dynamic stabilization is being studied. In conclusion : Treatment strategies not standardized most patient respond to conservative treatment. Anterior fusions increases & hear stress on adjacent discs Posterior fusions increases shear stress on facet jonits.

Most articles are in favour of treating degenrative spondylolisthesis with decompression and arthrodesis Inter body fusion has immediate mechanical and biologic advantage over intertransverse and should be considered if : 1- failed posterior fusion 2- those at risk of failed fusion 3- those which axial loads may exceed bending strength of implant. Isthmic in adult has benign course without surgery In degenerative may do no fusion if extensive stabilizing changes exist.

Thank You