Unilateral vs Bilateral Posterior Lumbar Interbody Fusion

Possibilities and Limitations in the Interbody Space Restoration

Poster presented at Eurospine 2003, 5th Annual Meeting of the Spine Society of Europe, October 1-4, 2003, Prague, Czech Republic.

During an interbody arthrodesis, the restoration of the disc heigh, the balance obtained in the frontal and coronal plane, a possible reduction of slippage contribute to neurological decompression. These elements also influence spinal balance.

STUDY:

These actions on the interbody space restoration have been analysed in this study, wich focuses on 193 levels done by T.L.I.F. on 152 patients from 1997 to 2003. These results are compared to another serie done by P.L.I.F. from 1992 to 1996, comprising 73 levels on 56 cases. Both series were performed by the same operator.

This comparative study help to clarify the impact of the various parameters that influence the result obtained, in particular,

-The heigh of the interbody space before intervention,

-The quality of the vertebral endplates

-The positioning of the impacted cages

-The effect of the lordosis created by the construct.

RESULTS:

These results were studied immediately, post-operatively and at one-year follow up.

 

          Discopathie, T.L.I.F. one plate, anterior situation of the cages,  good lordosis           and moderate restoration of the posterior interspace  heigh.                           

                              

 

 

 

                                                                                              

             

             Discopathie, T.L.I.F one plate, posterior situation of the cages = Little              lordosis, important  restoration of the posterior heigh

                                        

 

              

 

                                                                                                                        

                

                Degenerative S.P.L., thick disc, T.L.I.F. two plates, anterior placement of                 the cages= Good lordosis and  interspace heigh preserved                                                         

 
 

              

              Discopathie with thin disc, T.L.IF. one plate, restoration oh the heigh,               preservation of the frontal balance
 

                         

  

                     In spite of some dispersal results T.L.I.F. gives better lordosis ans more moderate restoration                                                               of the posterior disc heigh than    P.L.I.F.

 

The preservation of the major part of the soft ligament tissues at once anteriorely and posteriorely and the placement of the contro lateral cage wich was been pushed lateraly occurs a strong wedge effect, the increase of the heigh of the space tighten both anterior and posterior soft tissues similar to ligamentotaxis; and if the cage is placed anteriorely in the interspace, it is possible to obtain a lordosis effect. Moreover the presure on this cage insure its stability.

Images thanks to Prof W. Rauschning

CONCLUSION :

The comparison of the series showed that the unilateral approach achieves a correction and biomechanical construct wich is either comparable or an improvement over the P.L.I.F. technique. There are limitations to the unilateral technique, notably with osteoporosis, wich have lead the author to technical refinements.