The Biodegradable Intramedullar Nail

Abstract

The conventional metal intramedullar nail has considerable drawbacks. A second operation is often needed to remove the nail after fracture healing. The stress-shield phenomenon can cause impaired fracture healing, and there is the possibility of infection, allergic reaction and corrosion.
To avoid these problems a biodegradable interlocking nail was developed. Ideally, the biodegradable intramedullar nail will lose its strength gradually during a controlled degradation pattern and the load on the fractured bone will gradually shift from implant to bone.
The results of a long term follow up study (4 years) in an animal model using adult sheep are presented in this paper.
A self-reinforced polylactide intramedullar nail was used for the fixation of an artificially made femoral fracture.
The following parameters were subject of investigation: clinical fracture healing, radiological results, mechanical properties of the bones and local and regional histological response.
Macroscopically some shortening and angulation of the fractured femora was observed. The clinical healing was unimpaired and the mechanical tests were excellent in four sheep. Histological analysis showed a mild tissue response and a partial degradation of the implant.

Zusammenfassung

Im Folgenden werden die Resultate einer tierexperimentellen Langzeitstudie beschrieben, wobei ein so genannter „selfreinforced” Polylaktat-Marknagel benutzt wurde bei der Stabilisierung von künstlich bei Schafen zugebrachten Oberschenkelbrüchen.
Bei den nach vier Jahren obduzierten Schafen wurden die folgenden Parameter analysiert: Frakturheilung, Radiologiebefunde, mechanische Knocheneigenschaften und die lokale sowie regionale Gewebereaktion.
Makroskopisch beobachteten wir eine gewisse Verkürzung sowie eine Angulation der stabilisierten Femora. Die klinisch beurteilte Knochenheilung war uneingeschränkt und mechanische Tests waren exzellent. Die histologische Analyse wies eine milde Knochengewebereaktion auf sowie eine partielle Degradierung des Implantats.

Key words

Intramedullar osteosynthese - Biodegradable - Polylactid acid

Schlüsselwörter

Intramedulläre Knochenstabilisierung - Polylaktat - Biologisch abbaubar

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