THE LUMBAR LIGAMENTUM-FLAVUM - ANATOMIC F EATURES REGARDING MICRODISCOTOMY

One important step in lumbar discotomy is the safe penetration and exa kt partial removal of the Lig. flavum. This is a crucial prerequisite for the selective and gentle removal of prolapsed and sequestrated int ervertebral disc tissue. Extensive lancing of the Lig. flavum should b e avoided, to minimize intraoperative and postoperative complications, such as injuries to the nerves and the Dura mater, instabilities, ble eding and scarring. As there has up to now been insufficient informati on on the anatomy of the Lig. flavum especially regarding microdiscoto my, an analysis of the Ligg. flava L2/L3 to L5/S1, guided by this aim, was carried out on 36 corpses kept in formaline (16 f, 20 m; 52-75 y) . Preparations showed the lumbar Ligg. flava to be embodied in the For amina interarcualia in a characteristic configuration. There also prov ed to be defined insertion areas on the laminae of the vertebral arche s, which must be taken into consideration during the operative exposur e. The Lig. flavum rises from the cranial vertebral arch from the vent ral surface of the lamina (6,8 mm) whilst the insertion area on the ca udal lamina covers the dorsal and the ventral surface. The extent at t he ventral surface is 2.2 mm in average. Taking the insertion proporti ons into account we would suggest the Lig. flavum to be divided as fol lows: -Pars interspinalis, which clearly differs from the Lig. intersp inale (and from the M. interspinalis), and which houses venous anastom oses in its dorsal, ridge-shaped extension, -Pars interlaminaris, whic h starts at the laminae and constitutes the target area for flavotomy in its lateral section,and -Pars capsularis, which merges into the cap sular structures of the facets. In all levels examined, there proved t o be dorso-ventrally a typical change in the direction of the course o f the fibres in the Pars interlaminaris. Whilst the direction of the f ibres dorsally is oriented cranio-medially to caudo-laterally at an an gle between 15 degrees and 30 degrees to the median line. the ventral fibres of the Lig. flavum are strictly aligned cranio-caudally. The ch anges in the directions of the fibres are continous with the fibres be ing very closely intertwined, without there being any spatium at all. The texture of the Lig. flavum is, therefore, a mirror image of that o f the autochthonuous muscular system of the back, even if the overlapp ing angle area is considerably smaller. The different segment levels s how a segment-specific thickness profile. The analysis has provided an atomic information about the Ligg. flava L2/L3 to L5/S1. These data re present important prerequisites for a selective, gentle and safe intra operative procedure for discotomy.