OrthoNet

Spondylolisthesis
Approach to Spondylolisthesis

Wiltse Classification (“Did Tim Pass”)

I - Dysplastic
- IA - axially oriented facets; IB - sagitally oriented facets
- dysplastic facets permit forward translation - higher chance for neural compression as the intact posterior elements move forwards

II - Isthmic
- IIA - lytic defect in pars; IIB - elongated (partially healed lytic lesion)

III - Degenerative

IV - Traumatic

V - Post-Surgical

- children get isthmic spondylolysis and spondylolisthesis at L5/1; adults get degenerative spondy at L4/5
- an acquired disorder; possibly a stress fracture of the pars after repetitive microtrauma
- increase in slippage is seen during adolescent growth spurt; progression is unlikely after adolescence; therefore, like in adolescent scoliosis, get an idea of how skeletally mature they are when deciding about risk of progression.
- initial slippage of 50% is predictive of further slippage
- slip angle measures lumbosacral kyphosis and is associated with a higher risk of progression
- look for a rounded off sacrum or trapezoidal L5 body - higher chance of progression
Approach

Grade I and II slips that are asymptomatic (found spuriously)
- observation semiannually until age 15, then annually until the end of growth
- may give them advise about avoiding hyperextension activities and contact sports
- a 20% slip that progresses to 35% is not necessarily an indication for fusion - assess the above factors and watch - look at skeletal maturity, high slip angle, rounded sacrum or trapezoidal shape of L5 as useful markers of progression.
closesly. A 20% slip that progresses to 50% is probably an indication that you better get on an fuse it.

Grade I and II slips with pain
- activity restriction, NSAIDs, local measures, stretching exercises
- if continues to have pain - thoracolumbar orthosis
- if pain persists with orthosis, can do a L5-S1 posterolateral in-situ fusion with bone graft followed by single or double leg hip spica cast

Grade III or IV slips with or without symptoms
- gets a L4-S1 posterolateral in situ fusion with bone graft as a preventative measure for further progression if they are asymptomatic. Must extend fusion up to L4 because of the biomechanical disadvantage of the fusion mass.

- instrumented fusions are becoming popular but do not have the long-term track record of the standard posterolateral uninstrumented in-situ fusion. Instrumented reduction is hazardous to the nerve roots
- if they have documented MOTOR weakness, you should probably decompress them, which also means that you are going to go midline and destablize them - they need to be instrumented.
* when you position them prone in the OR, position them with their hips and legs EXTENDED - if you allow them to flex like they normally do, their lumbosacral kyphosis worsens, and they are apt to get a cauda equina syndrome. Cauda equina can occur with reductions and with in-situ fusions as well - requires sacroplasty