Franz Lassner

The role of microstructured and interconnected pore channels in a collagen-based nerve guide on axonal regeneration in peripheral nerves.

The use of bioengineered nerve guides as alternatives for autologous nerve transplantation (ANT) is a promising strategy for the repair of peripheral nerve defects. In the present investigation, we present a collagen-based micro-structured nerve guide (Perimaix) for the repair of 2 cm rat sciatic nerve defects. Perimaix is an open-porous biodegradable nerve guide containing continuous, longitudinally orientated channels for orientated nerve growth. The effects of these nerve guides on axon regeneration by six weeks after implantation have been compared with those of ANT. Investigation of the regenerated sciatic nerve indicated that Perimaix strongly supported directed axon regeneration. When seeded with cultivated rat Schwann cells (SC), the Perimaix nerve guide was found to be almost as supportive of axon regeneration as ANT. The use of SC from transgenic green-fluorescent-protein (GFP) rats allowed us to detect the viability of donor SC at 1 week and 6 weeks after transplantation. The GFP-positive SC were aligned in a columnar fashion within the longitudinally orientated micro-channels. This cellular arrangement was not only observed prior to implantation, but also at one week and 6 weeks after implantation. It may be concluded that Perimaix nerve guides hold great promise for the repair of peripheral nerve defects.

Sensory reconstruction of the fingertip using the bilaterally innervated sensory cross-finger flap.

&NA; The authors present a series of 15 patients with large soft‐tissue defects of the fingertips as a prospective, nonrandomized study. In all cases, reconstruction was achieved using a bilaterally innervated sensory cross‐finger flap. This sensory fasciocutaneous flap relies on the dorsal branch of the proper digital nerves, which branch off at the level of the head of the proximal phalanx; sensory supply to the dorsal skin of the middle phalanx is thus ensured. The reconstructive procedure consists of two steps. First, the contralateral dorsal branch of the proper digital nerve is elevated with the flap at proximal interphalangeal joint level. Microsurgical coaptation is performed to the proximal nerve stump of the injured fingertip. After 3 weeks, when the pedicle is dissected, the second nerve is dissected and coapted. Clinical results were evaluated after 12 months. Because the regenerative distance is only 1.5 to 2.5 cm, good sensory regeneration should be expected. In nine of 16 flaps, sensory quality of S2+ (Highet) was present in the flap after 3 weeks. After 12 months, two‐point discrimination was present in all patients, the values ranging between 2 and 6 mm (for twopoint discrimination), with an average of 3.6 mm. The rate of complications was low. With acceptable additional operative action, a good functional result can be achieved. The indications of this method are discussed in comparison with other methods of fingertip reconstruction. (Plast. Reconstr. Surg. 109: 988, 2002.)

Viability of cultured nerve grafts: An assessment of proliferation of Schwann cells and fibroblasts

Previous studies demonstrated that the viability of nerve grafts had a positive effect on nerve regeneration, while the cold storage of nerve grafts obtained few viable cells at the later stage. The purpose of this study was to examine the cellular activities of Schwann cells and fibroblasts in cultured nerve grafts prior to transplantation. 2.5‐cm long sciatic nerve grafts were harvested from 75 male Lewis rats. Two different media were utilized to culture the nerve grafts up to 3 weeks: Dulbeccos modified eagle medium (DMEM) only or DMEM supplemented with 2 μM forskolin and 10 μg/ml pituitary exact (mitogen medium for Schwann cells). In vivo predegenerated and normal nerve grafts were used as positive and negative controls, respectively. We employed a 5‐bromo‐2′‐deoxyuridine (BrdU) incorporation method to evaluate the proliferating cells in the cultured nerve grafts. S‐100 and vimentin immunostaining were used to estimate the presence of Schwann cells and fibroblasts in all nerve grafts at different intervals. The results showed that the proliferating cells increased progressively under culture conditions. The proliferating cells distributed evenly in small fascicles (average diameter 251 ± 71.5 μm), whereas they appeared mainly in the margin of large fascicles (average diameter 624 ± 87.3 μm). The mitogen medium stimulated Schwann cell multiplication more significantly in comparison with DMEM after 3 days of culture (P < 0.01), however, there were fewer fibroblasts present in the mitogen medium than in DMEM after 2 days of culture (P < 0.01). It is suggested that the viability of nerve grafts can be preserved under culture conditions. Furthermore, the cellular activity of the Schwann cells and fibroblasts in nerve grafts can be manipulated in in vitro Wallerian degeneration.

The cervical rib: A PREDISPOSING FACTOR FOR OBSTETRIC BRACHIAL PLEXUS LESIONS

Controversy surrounds the aetiology of obstetric brachial plexus lesions. Most authors consider that it is caused by traction or compression of the brachial plexus during delivery. Some patients, however, present without a history of major traction during delivery, and some delivered by Caesarean section also suffer the injury. In our series of 42 infants, 28 had an Erbs palsy, and the remaining 14 presented with a more extensive lesion, involving the lower roots. In five of these, a complete ossified cervical rib was found. We believe that anatomical variations, such as cervical ribs or fibrous bands, can cause narrowing of the supracostoclavicular space, and render the adjacent nerves more susceptible to external trauma.

TIMING OF FREE MICROSURGICAL TISSUE TRANSFER FOR THE ACUTE PHASE OF HAND INJURIES

Because of favourable survival rates in replantation surgery and a high standard of free tissue transfer the interval between injury and microsurgical reconstruction has become gradually shorter. The acute phase can be defined as the interval ranging from emergency procedures within 24 hours to urgent procedures done within 72 hours. Bearing in mind the infection rates that have been reported of 1.5% for the acute phase and 17.5% for the late phase, we should encourage emergency reconstructions. However, in most cases of upper extremity injuries, reconstruction with conventional flaps is possible. Between 1981 and 1995 we did 72 acute post-traumatic free tissue transfers to the upper extremity in our unit within 72 hours (urgently). There were no significant differences in the incidence of infections when acute were compared with urgent procedures. As a result we support the concept of urgent operations. The following advantages are to be considered: urgent operations allow a second look operation, the viability of the extremity can be assessed, and the reconstructive procedure can be planned more precisely. Last but not least, the procedure is done during the day time with better operating conditions.

Replantation of the complete external genitals.

Most cases of genital amputation represent an isolated penile amputation; the combined amputation of both penile and testes is reported very seldom. We describe a case of complete amputation of the external genitals with successful replantation and good functional outcome. The problem is analyzed with respect to operative strategy, ischemic periods, postoperative management, and psychiatric background. For the replantation of the testes, time frames are comparable to those for macroreplantations.

The cervical rib

Controversy surrounds the aetiology of obstetric brachial plexus lesions. Most authors consider that it is caused by traction or compression of the brachial plexus during delivery. Some patients, however, present without a history of major traction during delivery, and some delivered by Caesarean section also suffer the injury. In our series of 42 infants, 28 had an Erbs palsy, and the remaining 14 presented with a more extensive lesion, involving the lower roots. In five of these, a complete ossified cervical rib was found. We believe that anatomical variations, such as cervical ribs or fibrous bands, can cause narrowing of the supracostoclavicular space, and render the adjacent nerves more susceptible to external trauma.

Therapie des Weichteiltraumas in der Akutphase von schweren Handverletzungen

Abstract.Introduction: Complex hand injuries are characterized by a combination of soft tissue injury and additional trauma to functional structures such as nerves, bones, tendons, vessels and joints. A good functional result requires the reconstruction of the injured structures and early mobilisation. Good vascularized soft tissue and stable osteosyntheses are the major prerequisites to avoid infections and to allow early mobilisation. The optimal timing for soft tissue reconstruction remains controversial with respect to the incidence of infections. Methods: We have evaluated retrospectively our series of complex hand injuries adressing the question whether a delay of soft tissue coverage for up to 72 hours causes significant increase of infection rates. Results: 48 patients were treated with complex injuries of the hand within a three year period between December 1998 and December 2000. The lowest incidence of infections occured in the group, where soft tissue coverage was completed as an emergency procedure. Discussion: Ideally primary reconstruction of complex hand injuries should be strived for to minimize scar formation as a result of secondary operations and further immobilisation periods. This includes, if necessary, free tissue transfer. Exceptions are situations where the vitality of soft remains uncertain. In these cases, definitive surgery is delayed for a maximum period of 72 hours.Zusammenfassung.Einleitung: Komplexe Handverletzungen sind durch eine Kombination von schwerem Weichteilschaden und Zusatzverletzungen (Frakturen und Mitbeteiligung funktioneller Strukturen wie Nerven, Sehnen, Gefäße, Gelenken und Bandapparat) charakterisiert. Ein gutes funktionelles Ergebnis kann nur erzielt werden, wenn nach Wiederherstellung der verletzten Strukturen eine frühe Übungsbehandlung möglich ist. Gut durchblutete Weichteile und übungsstabile Osteosynthesen sind die wesentliche Voraussetzung zur Vermeidung von Infekten und zur Durchführung einer frühfunktionellen Behandlung. Zur Frage des Zeitpunktes der Rekonstruktion der Weichteile gibt es divergierende Meinungen, insbesondere was das Risiko für Wundinfektionen anbelangt. Methoden: In einer retrospektiven Studie wurden die Komplexverletzungen der Hand an der Klinik für Plastische Chirurgie, Hand- und Verbrennungschirurgie unter der Fragestellung nachuntersucht, ob eine um bis zu 72 Std. verzögerte Rekonstruktion der Weichteile einen Einfluss auf die Häufigkeit von Wundinfekten hat. Ergebnisse:Über einen Zeitraum von 3 Jahren von Dezember 1998 bis Dezember 2000 wurden 48 Patienten mit komplexen Handverletzungen behandelt. Die niedrigste Infektrate wurde in der Gruppe erreicht, bei der die Defektdeckung notfallmäßig erfolgte. Diskussion: Idealerweise sollte eine komplette Primärversorgung angestrebt werden, um weitere Narbenbildung durch spätere operative Eingriffe sowie zusätzliche Immobilisierungszeiten zu minimieren. Diese schließt den notfallmäßigen freien Gewebetransfer ein. Ausnahmen werden da gemacht, wo die Vitalität der Weichteile primär nicht sicher beurteilbar ist. In diesem Fall erfolgt die Versorgung innerhalb der 72-Std.-Grenze.

Peripheral nervous system: Neuro-Tissue Engineering using a microstructured collagen matrix

Reconstruction of peripheral nerve lesions remains a major challenge in reconstructive surgery. The aim of this tissue engineering approach is the development of a bioartificial nerve graft on basis of a specifically designed cylindrical collagen scaffold. The developed cylindrical collagen scaffolds resulted in an advanced interaction between Schwann cells and the nerve guide in-vitro. Both in-vitro and in-vivo regeneration experiments revealed appropriate regeneration with axonal sprouting reaching the distal end of the guidance channels in an orientated manner.

Verletzungen des Plexus brachialis

Schadigungen des Plexus brachialis treten in den Industrienationen bei 0,19–2,5 Kindern pro 1.000 Lebendgeburten auf, in Entwicklungslandern bei 3,6 Kindern pro 1.000 (Soni et al. 1985). Bei diabetischer Stoffwechsellage der Mutter steigt das Risiko auf uber 10 % (Acker et al. 1988). Aus ca. 800.000 Geburten pro Jahr im deutschen Raum ergibt dies eine Anzahl von 150–2.000 Neugeborenen mit geburtstraumatischer Plexuslasion. Bei mehr als der Halfte dieser Kinder (50–85 %) kommt es zu einer Spontanregeneration mit befriedigenden funktionellen Ergebnissen (Michelow et al. 1994). Es muss das Ziel der therapeutischen Bemuhungen sein, die restlichen Kinder, die keine spontane Regeneration zeigen, rechtzeitig einer chirurgischen Therapie zuzufuhren.