Ersatz des Nucleus pulposus Aspekte eines Nachbehandlungsprogramms
Verlust/Entfernung von NP 38% - 100% Zunahme der spinalen Beweglichkeit mit den Konsequenzen: - bei axialer Belastung quillt die äußere Region des Anulus nach außen, die innere ins Zentrum - Anulus Fissuren - Prolapsen - reduzierte Kapazität gegen Scherkräfte
Ziele bei NP-Ersatz: - Retension anulus - Preserve endplate cartilage - Restore normal load distribution - Restore normal hydraulic pumping mechanism - Restore spine kinematics, shock absorption - Minimally invasive implantation
Anforderungen an NP Implantate: - Den Degenerationsprozess reduzieren - Biokompatibel ohne Toxizität oder Karzinogenität - Belastungsstabil - bei angenommenen ca. 5500 Schritten/Tag: ca. 100 Millionen Belastungswechsel in 40 Jahren - leicht sein bei geringem Abrieb - gleiche Festigkeit wie natürlicher NP - muss sich an Deckplatten anschmiegen - den gesamten Raum ausfüllen - minimal invasiv einzubringen sein, um fibrosus zu erhalten
Zwei Arten von NP Implantaten: a) Intradiskale Implantate b) in situ (= vorort) aushärtende Polymere
a) Intradiskale Implantate PDN - 1988 entwickelt - ab 1998 in klinischen Studien - Hydrogel kann 80% des Eigengewichtes an Wasser aufnehmen - eingebettet in Polyäthylen Tasche PDN Solo (Prosthetic Disc Nucleus)
The Aquerelle Poly(vinyl alcohol) hydrogel has a swelling pressure similar to the nucleus pulposus in vivo. A, Once implanted, iits final volume depends on the water content at equilibrium. B, Lateral radiograph showing the cavity dimension measurement after insertion of a 4- to 5-mm cannula in the disc space via a lateral access in the cadaveric spine. C, Anteroposterior radiograph of the implanted Aquarelle device in a cadaveric specimen. (Reprinted with permission from Stryker Spine, Allendale, NJ.)
b) in situ aushärtende Polymere DASCOR Disc Arthroplasty Device. A, Implantation of the device with a trochar (arrow) via a lateral approach in a sawbone model. Axial (B) and sagittal (C) lumbar MRI sections in a patient 6 weeks after surgery. S20 Spine Volume 30 Number 16S 2005
b) in situ aushärtende Polymere BioDisc - Protein hydrogel - per Injektion direkt in den Discus - härtet in wenigen Minuten aus
Contraindications for artificial disc replacement Psycho-social issues Systemic processes (infection, tumor) Segmental instability, spondylolisthesis Disc height < 5 mm or > 12 mm Incompetent posterior elements, facets Incompetent end plate Osteoporosis Obesity (weight > 90 kg, body mass index > 30)
Aspekte der Nachbehandlung bei NP Implantaten (PDN): 24 hours bedrest 3 - point brace (4-6 weeks) early mobilization early physiotherapy (1st day) return to work (4-6 weeks) back to sports / normal activity after 6 weeks
General treatment steps 1) stability Training/educating to improve the capacity for axial loading; reduction of shear and bending forces
General treatment steps 1) stability Improvement of muscle force (transverse abdominal and multifidi muscles) Elastic brace to improve intraabdominal pressure and thus lumbar stability
General treatment steps 1) stability ADL-training
General treatment steps 2) Mobility Multidirectional training
General treatment steps 3) Optimisation of coordination / reflexes trainings ball / mini trampoline
Individual evaluation 1) mechanism of failure / cause? - R/o lumbar hypermobility / compensatory malpositions - reduced thoracic mobility - reduced hip mobility Goal: creation of individual preventive trainings program
Proposed steps Creation of specific trainings programs by specialists Teaching of doctors during Biodisc courses Special courses for physiotherapists? Prove concepts by clinical studies
The End With Biodisc (nearly) everything is possible