[Indication, biomechanics and early results of artificial disk replacement].
OBJECTIVE
Judgment of factors concerning the indication for the implantation of an artificial disc endoprosthesis, the rating of this operation and biomechanical considerations.


METHODS
Presentation of the indication and the value of a new operative concept in comparison to a so-called dynamic stabilization procedure (Dynesys' method). Indications for the operation are: unsuccessful, orthopedic conservative treatment for > 6 months, segmental pain, age < 45 years, evidence of an MRI demonstrable mono- or bisegmental disc degeneration with or without disc prolabation, exclusion of psychogenic disease and positive preoperative, diagnostic measures such as facet joint infiltration and discography.


RESULTS
In an earlier investigation the efficacy of the Link method was demonstrated as shown by the reduction of the analgesic use, the angle of the lumbar lordosis (L1-S1) increased from 35.6 degrees to 42.6 degrees (20.2 %), the segmental angle from 19 degrees to 30 degrees (57.5 %). The new investigation using the Aesculap endoprosthesis resulted in a change of the angle of lumbar lordosis from 35.4 degrees to 45.4 degrees (25.4 %) and a change of the segmental angle from 17.3 degrees to 29.1 degrees (57.6 %). This method is a real endoprosthetic instrumentation in the field of spinal surgery.


CONCLUSIONS
In younger patients with mono- or bisegmental disc degeneration there is an indication for the implantation of a disc endoprosthesis. A facet joint arthrosis and an age over 45 years are contraindications for the operation. The indication in patients with a classic failed back surgery syndrome is still unclear, the improvement of the instrumentation and a further adaptation of the systems to the known biomechanics of the lumbar spine are mandatory as is an intensive discussion of the operative procedure in the case of revision operations. The Dynesys method, with the inherent danger of segmental kyphozitation, a published, significant revision quota combined with a reduction of motility, does not fulfill this criterion.
Hopf
C
C
Abt. für Wirbelsäulenchirurgie, Kinder, Rheuma- und onkologische Orthopädie, Lubinus Klinik Kiel. C.Hopf@lubinus-clinicum.de
Heeckt
H
H
Beske
C
C
D000328:Adult; D000368:Aged; D001416:Back Pain / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery*; D001696:Biomechanical Phenomena / Q000379:methods; D019544:Equipment Failure Analysis; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000175:diagnosis* / Q000601:surgery*; D007593:Joint Instability / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery*; D007595:Joint Prosthesis; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D016059:Range of Motion, Articular; D018570:Risk Assessment / Q000379:methods; D016896:Treatment Outcome