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.

Intramedullar osteosynthese - Biodegradable - Polylactid acid

Intramedulläre Knochenstabilisierung - Polylaktat - Biologisch abbaubar

References

• 1 Böstman O, Partio E K, Hirvensalo E, Rokkanen P. Foreign body reactions to polyglycolide screws.  Acta Ortho Scand. 1992;  63 173-176
• 2 Bramer J AM, Barentsen R H, vd Elst M, de Lange E SM, Patka P, Haarman H JThM. Representative assessment of long bone shaft biomechanical properties: an optimized testing method.  J Biomech. 1998;  31 741-745
• 3 Elst van de M, Dijkema A RA, Klein C PAT, Patka P, Haarman H JThM. Tissue reaction on PLLA versus stainless steel interlocking nails for fracture fixation: an animal study.  Biomaterials. 1995;  34 103-106
• 4 Elst van de M, Klein C PAT, de Blieck-Hogervorst J M, Patka P, Haarman H JThM. Bone tissue response to biodegradable polymers used for intra-medullary fracture fixation: A long term in vivo study in sheep femora.  Biomaterials. 1999;  20 121-128
• 5 Elst van de M, Bramer J AM, Klein C PAT, Lange de E SM, Patka P, Haarman H JThM. Biodegradable interlocking nails for fracture fixation.  Clin Orthop. 1998;  357 192-204
• 6 Elst van de M, Patka P, Werken vd C. Resorbierbare Implantate für Frakturfixierungen.  Unfallchirurg. 2000;  103 178-182
• 7 Kallella I K, Iizuka T, Salo A, Lindqvist C. Lag screw fixation of the anterior mandibular fractures using biodegradable polylactide screws: A preliminary report.  J Maxillofac Surg. 1999;  57 113-118
• 8 Kulkarni R K, Pani K C, Neuman C, Leonard F. Polylactic acid for surgical implants.  Arch Surg. 1966;  93 839-843
• 9 Majola A, Vainionpaa S, Rokkanen P, Mikkola H M, Thormala P. Absorbable selfreinforced polylactide (SR-PLA) composite rods for fracture fixation.  J Mat Sci Mat Med. 1992;  3 43-47
• 10 Rokkanen P, Bostman O, Vainionpaa S. et al . Biodegradable implants in fracture fixation: early results of treatment of fractures of the ankle.  Lancet. 1985;  1422-1424
• 11 Simon J A, Ricci J L, Di Cesare P E. Bioresorbable fracture fixation in orthopedics: a comprehensive review. Part II. Clinical studies.  Am J Orthop. 1997;  26 754-762
• 12 Suming L i. Hydrolytic degradation characteristics of aliphatic polyesters derived from lactic and glycolic acids.  J Biomed Mater Res. 1999;  48 342-353
• 13 Tonino A J, Davidson C L, Klopper P J, Linclau L A. Protection from stress in bone and its effects.  J Bone Joint Surg [Br]. 1976;  58 169-181
• 14 Tormala P, Vasenius S, Vainionpaa S, Laiho J, Pohjonen T, Rokkanen P. Ultra-high-strength absorbable selfreinforced polyglycolide (SR-PGA) composite rods for internal fixation of bone fractures: In vitro and in vivo study.  J Biomed Mater Res. 1991;  25 1-22
• 15 Vert M, Li S M, Spenlehauer G, Guerin C. Bioresorbability and biocompatibility of aliphatic polyesters.  J Mater Sci Mater Med. 1992;  3 432-446