Cage

Abstract: The invention relates to a cage-type intervertebral implant that is made up of a dished side wall ( 1 ), a cambered side wall ( 2 ), a front part ( 3 ), a rear part ( 4 ) and at least one intermediate wall ( 5, 6 ), thus comprising at least two cavities ( 7, 8, 9 ) An upper and a lower cage surface ( 10, 11 ) include a first lordosis angle (α 1 ) in the direction front part—rear part and a second lordosis angle (α 2 ) perpendicular thereto, said cage surfaces ( 10′, 11 ) intersecting outside the cage The cage structure is characterized by a double-wedge geometry (double-wedge-shaped cage) that is defined by the two lordosis angles (α 1 ) and (α 2 ) and that advantageously adapts itself to the anatomical conditions in the intervertebral area The cage is further characterized by a high moment of tilt that effectively counteracts a tipping of the cage The method used for producing the cage structure is essentially characterized by working the cage material by means of a high-pressure water jet, said cold-cutting technique having proved to be the most economical

Abstract: In posterior lumbar interbody fusion, cage migrations and lower fusion rates compared to autologous bone graft used in the anterior lumbar interbody fusion procedure are documented Anatomical and biomechanical data have shown that the cage positioning and cage type seem to play an important role Therefore, the aim of the present study was to evaluate the impact of cage positioning and cage type on cage migration and fusion We created a grid system for the endplates to analyze different cage positions To analyze the influence of the cage type, we compared “closed” box titanium cages with “open” box titanium cages This study included 40 patients with 80 implanted cages After pedicle screw fixation, 23 patients were treated with a “closed box” cage and 17 patients with an “open box” cage The follow-up period averaged 25 months Twenty cages (25%) showed a migration into one vertebral endplate of <3 mm and four cages (5%) showed a migration of ≥3 mm Cage migration was highest in the medio-medial position (846%), followed by the postero-lateral (429%), and the postero-medial (16%) cage position Closed box cages had a significantly higher migration rate than open box cages, but fusion rates did not differ In conclusion, cage positioning and cage type influence cage migration The medio-medial cage position showed the highest migration rate Regarding the cage type, open box cages seem to be associated with lower migration rates compared to closed box cages However, the cage type did not influence bone fusion