Search PubMed⌕ Search

Biomedical subjects

J Brennwald

Publications and source records attributed to J Brennwald.

At least 19 recordsLinked to original sources
PubMed1997

Functional and morphological outcome of knee joint transplantation in dogs depends on control of rejection.

BACKGROUND: The reconstruction of massive osteochondral defects extending to weight-bearing joints remains a surgical challenge. Total knee joint transplantation has been performed experimentally, but these studies lacked prospective evaluation of functional outcome, graft vascularization, and graft viability. METHODS: Replantation and transplantation of vascularized knee joints was performed in dogs (n=4 per group), comparing functional and morphological results during a 6-month follow-up. RESULTS: All replant recipients and three transplant recipients survived the 6-month follow-up period. At this time, duplex sonography and angiography revealed patent anastomoses in all animals. Increases in volumetric flow rates and vascular collateralization were observed in allografts, as compared with replanted joints (100+/-16 ml/min vs. 31+/-15 ml/min at 6 months after transplantation). Bone fusion at the graft-host interface was verified by fluorography in all animals at 3 months after transplantation. Six months after transplantation, microradiographies and computerized tomographies revealed spongialization of the cortical bone and filling of the medullary space by trabecular bone in transplanted joints. Such alterations were not detectable in replanted joints. Chondrocyte viability exceeded 80% in all but one transplanted joint. Lymphocyte infiltration of synovia and arterial walls was detected in all transplanted joints, suggesting the presence of chronic rejection. Weight-bearing capacity recovered in all replanted animals (weight-bearing index before transplantation: 0.499+/-0.080; 6 months after transplantation: 0.38+/-0.16) but only in two of four transplanted animals (weight-bearing index 6 months after transplantation: 0.37, 0.28, and 0.00). CONCLUSIONS: These data demonstrate the potential of joint grafting and the critical dependence of allotransplantation on the control of rejection.

Angiography↗
PubMed1997

Prospective multicenter trial of a plate for dorsal fixation of distal radius fractures.

A new plate designed specifically to address complex wrist pathology was used for the internal fixation of 22 complex fractures of the distal radius in 22 patients in a prospective multicenter trial. The majority of fractures were group C2- and C3-type fractures according to the Comprehensive Classification of Fractures. No plate failures, loss of reduction, nonunions, or infections occurred. Within the average follow-up time of 14 months, the functional results (including an average motion of 76% and an average grip strength of 56% of the contralateral side) were comparable to those reported for similar fractures in previous investigations. Five patients had irritation of the tendons in the second dorsal compartment. This trial serves both as a verification of the safety and efficacy of this distal radius plate as well as a demonstration of its utility in the treatment of complex fractures of the distal radius.

Adult↗
PubMed1996

Fracture healing in the hand. A brief update.

Before the introduction of internal fixation, the healing of a fracture was an unpredictable event. Internal fixation provides stability, and fractures heal predictably. Continued research has allowed better understanding of fracture healing, and the biology of the bone tissue has become the focus. It has been discovered that a higher success of union and an earlier union results from avoiding additional vascular injury to the fracture site. Understanding the vascularity of bone and improved technology has led to the development of smaller implants that minimize surgical trauma and provide sufficient stability.

Finger Injuries↗
PubMed1995

[Functional and morphological results of transplantation of vascularized knee joints in a dog model--a preliminary report].

Functional and morphological results of transplantation (n = 3) and replantation (n = 4) of vascularised total knee joints were compared in a canine model. Follow up time was 6 months. All vascular anastomoses remained patent and all osteotomies healed. Replanted animals displayed normal static weight bearing in contrast to the transplant recipients, which showed reduced weight bearing after 6 months compared to preoperative values. Mild to moderate signs of chronic allograft rejection were detected in all transplanted animals. Functional results were correlated with morphological outcome demonstrating the relevance of adequate control of rejection.

Animals↗
PubMed1994

Implants of pure titanium for internal fixation of the peripheral skeleton.

In a multicentre study, a clinical evaluation of the new titanium implants of the sizes 2.7, 2.0 and 1.5 mm was done. In seven centres, 133 patients were operated on and the personal, subjective opinions of the surgeons were recorded. In the opinion of these surgeons experienced in using steel implants, the outcome of the internal fixations was the same for titanium as for steel implants. Three metal-related complications occurred in the smallest size screw type (1.5 mm), namely, one screw broke and two bent. In the cases in which the implant had been removed, good tissue contact with the implant could be seen. Only in one case was there discolouring of the soft tissue due to titanium. It is recommended that surgeons who are used to handling stainless steel screws should be aware of the slightly different behaviour of titanium screws.

Adolescent↗
PubMed1994

[Surgical technique in vascularized auto- and allotransplantation of the knee joint in a dog model].

Experimental transplantation of vascularized canine knee joints has so far been associated with high complication rates in both auto- and allografts. We have now compared 4 autografts and 4 allografts that were successfully performed at our institution. This report details our surgical technique. Stable internal fixation enabling immediate postoperative weight bearing, microsurgical end-to-end anastomoses of popliteal artery and vein and postoperative control of immunosuppression in transplanted animals are crucial. Thus, an interdisciplinary approach of experts in microsurgery, orthopedic and trauma surgery and immunologists appears to be a prerequisite for successful joint transplantation.

Animals↗
PubMed1993

Fixation of vascularized bone grafts.

In 24 patients, fixation of isolated or combined bone grafts has been performed exclusively with miniplates. Other than the lateral displacement of one osteomyocutaneous iliac crest graft, no complication occurred with regard to the fixation method chosen. In contrast to the clinical findings, our results of an animal experiment demonstrate less complications by fixation of vascularized bone grafts to mandibular angle defects (guinea pig) when THORP plates are used instead of miniplates. Whereas we consider miniplate fixation of vascularized bone grafts to be the method of choice, selected patients may require more stable fixation systems, especially when a high postoperative mobility may be expected or large amounts of the mandible including the condyle have to be reconstructed.

Animals↗
PubMed1990

[Bone and joint transplantation. Alternatives to bridging segmental bone defects and a model for allogenic bone transplantation].

Fresh allogeneic diaphyseal bone segments were transplanted into 12 dogs. We attempted to improve the immunogenity and incorporation of the bone segments through "graft manipulation" with and without immunosuppression. Through clinical and radiological study during the 20-week experimental period, we observed transplant healing with differing structural phenomena. After autologous knee joint replantation in 4 dogs and allogeneic transplantation in 2 dogs (with and without revascularization and immunomodulation with Cyclosporin A) we present a canine model to investigate all open questions about the transplantation of allogeneic, fresh joints (i.e. transplant biology, immunology, and vitality).

Animals↗
PubMed1987

Bone healing in the hand.

Fracture healing in the hand is not an isolated goal. The functional end result is of paramount importance. The means of achieving a good functional result either by secondary bone healing over callus formation or through primary bone healing by direct remodeling is unimportant. By understanding both types of fracture healing, we can choose the proper treatment, and by handling the bony tissue correctly, we can avoid problems.

Bony Callus↗
PubMed1985

[Motor, sensory electroneurographic and electromyographic results as well as somatosensory evoked potentials in comparison to clinical findings following nerve suture].

A group of 37 patients (total 41 nerves) with a traumatic transection of median or ulnar nerves at the wrist were reinvestigated clinically and electrophysiologically 4-59 months after primary or secondary suture or grafting. Clinically there was no relation between the time after the operation, and sensory recovery determined according to the schedule of Nicholson and Seddon (1957), two-point discrimination, vibration threshold. There was also no relationship between the time after suture, and the motor latencies as well as amplitudes of evoked muscle action potentials from the abductor pollicis brevis or hypothenar muscles. In sensory nerve fibres there was a statistically significant increase of the maximum amplitude and of the cumulative amplitude during the period after operation, due to an increasing number of regenerated nerve fibres. Sensory nerve conduction velocities showed no relation to the time after suture. Cumulative amplitudes were significantly related to two-point discrimination and to restitution of sensibility. As indicated by the great scatter, however, this parameter is merely a moderate predictor for the degree of clinical recovery. Somatosensory evoked potentials can be helpful in some cases to indicate nerve regeneration when nerve action potentials in peripheral nerves cannot be recorded. However, latencies and amplitudes of the individual peaks did not reveal any relationship to either clinical findings or to period of time after operation. Needle electromyography also yielded highly variable findings. A constant finding was a persistent loss of motor units. Most of these were increased sin size, as indicated by prolonged duration of their action potentials during slight voluntary effort.

Adolescent↗
PubMed1985

[Experimental studies on artificial prostheses in microvascular surgery].

The need for microvascular grafts in replantation and free tissue transfer is well recognized. Variable results are reported in the literature. Therefore, an experimental study was undertaken to assess the suitability of an expanded PTFE (Polytetrafluoro-ethylene) as a microvascular graft. A 2.0 mm diameter graft was implanted in the artery and the vein of the rabbit. No graft in the venous system remained patent. From these animal experiments we conclude that there is no clinically applicable synthetic micro-graft available.

Animals↗
PubMed1985

[Osteotomy and osteosynthesis of the clavicle in brachial plexus surgery].

During the operative revision of the brachial plexus lesion the exposure is sometimes not wide enough without an osteotomy of the clavicle. The authors developed, therefore, a special technique consisting of internal fixation with a lag-screw prior to the oblique osteotomy of the clavicle. At the end of the operation stable internal fixation can be achieved within a few minutes. This internal fixation proved to be stable, even for passive mobilization in total plexus lesions in sixteen cases over a follow-up time over five years. Primary bone healing always occurred. The technique is described.

Bone Plates↗
PubMed1983

Sensory electroneurographic parameters and clinical recovery of sensibility in sutured human nerves.

A total of 37 patients with traumatic transection of median or ulnar nerves at the wrist (total 41 nerves) were examined clinically and electrophysiologically 4-59 months after primary or secondary suture or grafting. There was a significant increase of cumulative amplitude with the time after suture, whereas maximum sensory nerve conduction velocity and maximum amplitude of nerve action potentials did not reveal such a correlation. The recovery of two-point discrimination, vibration threshold and sensibility scored according to the scale of Nicholson and Seddon were also not related to the passage of time after operation. Though there were significant correlations between cumulative amplitude and both two-point discrimination and recovery of sensibility, electrophysiological parameters were shown to be inadequate predictors of clinical recovery.

Adolescent↗