QUICK TIPS ABOUT SURGICAL REDUCTION OF SPONDYLOLISTHESIS

Ref: Frymoyer

*Surgical reduction of spondylolisthesis is usually reserved for patients with high-grade dysplastic spondylolisthesis as defined by Marchetti and Bartolozzi
*The primary pathology addressed by reduction is significant lumbosacral kyphosis. Improvement in the accompanying translation is a by-product of correction of the kyphosis and is to be expected.
*Elements: exposure---->laminectomy------->complete exposure of 2 roots above ane below-------->complete discectomy and scral dome excision--->decorticzation of opposing surfaces ofL5 and S-1------>ant. graftting and titanium mesh cage--->place peicle screws---->distract, placethe rods and compress------>posterolateral bone grafting

* Goals: anterior column load sharing reestablish the posterior tension band negation of lumbosacral shear forces

*which x-rays? Thirty-six–in. erect anteroposterior and lateral radiographs of the entire spine (including the femoral heads) are the basic required films.Flexion extension lateral radiographs are of little value.A magnetic resonance image (MRI) without contrast of the lumbar spine is quite valuable. The MRI depicts the anatomy of the lumbosacral disc as well as the anatomy of the sacral dome, guiding the resection of the sacral dome. The posterior inferior lip of L-5 may provide an impediment for placing a structural graft into the lumbosacral space; this is usually seen on the MRI.

*The transforaminal lumbar interbody fusion (TLIF) approach is performed.

*Creation of a physiologic flap of annulus------>A medial-based rectangular flap is created with the scalpel, taking care to protect L-5 roots. A stay suture of 2-0 silk is placed. This flap is then used to retract the S-1 root medially while protecting it. An excellent window into the lumbosacral space is now present. Figure 4 is an illustration of the exposure via the transforaminal technique described. The physiologic retractor afforded by the posterior longitudinal ligament and annulus is demonstrated.
*Morselized autograft is then placed in the anterior one-third of the interspace and impacted.
*Polyaxial screws are preferred to facilitate rod placement.
*With all screws in place, an appropriate length rod is selected and bent to appropriate sagittal contours. A lordotic configuration is usual. The rod is placed in the sacral screws first, and the closure mechanism is tightened.
*The cantilever maneuver using the rods attached to the sacral screws has the primary function of producing lumbar lordosis, using the Harms titanium mesh cages as a fulcrum. This decreases the lumbosacral kyphosis and the slip angle. This maneuver also decreases the lumbosacral translation.Application of compression between the L-5 screws and the S-1 screws has additional biomechanical functions. Compression loads on the anterior structural grafts may perhaps enhance anterior arthrodesis. Compression also increases lumbosacral lordosis production, using the structural cages as a fulcrum.
*Platelet-rich plasma provides a good adhesive medium to prevent scattering of the morselized fragments. An alternative is multiple strips of corticocancellous bone from the iliac crest.