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Biomedical subjects

G O Hofmann

Publications and source records attributed to G O Hofmann.

At least 19 recordsLinked to original sources
PubMed1998

Allogenic grafting of vascularized bone segments under immunosuppression. Clinical results in the transplantation of femoral diaphyses.

Trauma surgery lack, substitute, for the reconstruction of large defects of the long bones. Encouraged by the promising results of bone allotransplantation in animal models, we successfully performed vascularized bone transplantation in humans. Vascularized femoral diaphyses were allogenically transplanted into three patients suffering from chondrosarcoma or post-traumatic osteomyelitis with postoperative immunosuppression. The bone segments were harvested from multi-organ donors and perfused with UW solution. After back-table preparation, the grafts were transplanted into the defect zone. Interlocking devices were used in these operations. Vascular anastomoses were performed in end-to-side technique. The early clinical course of the patients was not free of anatomical, technical, or immunological complications. However, all patients are currently free of malignancy and infection. They are also free of pain and full weight bearing. We conclude that allogenic grafting of vascularized bone segments has the potential to become an alternative for the replacement of large bone defects.

Adult↗
PubMed1998

Vascularized knee joint transplantation in man: a report on the first cases.

Four transplantations of an allogeneic vascularized human knee joint were performed at the Trauma Center Murnau between April 1996 and July 1997. The indication for the procedure was the total loss of the knee joint including the extensor apparatus due to severe trauma. These were the first transplants of this type. Management of patients started with closure of soft-tissue defects. After successful completion, stabilization was achieved with femoral and tibial nails plus a temporary arthroplasty. AB0 compatibility and a negative cross-match were the main criteria for selecting patients for transplantation. Interlocking compression nails were used for osteosynthesis. Vascular anastomoses between graft and recipient vessels were established by the end-to-side technique. Immunosuppression was started as a quadruple induction therapy for 3 days, then reduced to a two-drug maintenance therapy with cyclosporine and azathioprine. Six months posttrans-plantation the osteotomies were bridged by callus and the patients became completely mobile. Radiographic and histological examinations revealed vital graft tissue.

Adolescent↗
PubMed1998

Allogeneic vascularized grafting of human knee joints under postoperative immunosuppression of the recipient.

Vascularized knee joint transplantations have been performed in various animal systems. Up to now no allogeneic vascularized transplantation of a fresh and perfused human knee joint has been realized. This paper reports on the first four grafted human knee joints, performed between April 1996 and July 1997 at the Trauma Center Murnau. The indication for transplantation of a human knee joint is total loss of the joint, including the extensor apparatus, following severe trauma. Management of this defect is first to effect closure of the soft tissue defect combined with external transfixation and bone cement spacers. For the second phase the external stabilization is switched to internal stabilization using femoral tibial nails and a temporary knee joint prosthesis manufactured of polyethylene. The transplantations are performed with respect to ABO compatibility, ignoring the HLA system after a negative crossmatch. Osteosyntheses are employed by femoral and tibial nails. The vascular anastomoses are established in an end-to-side technique between the recipient's superficial femoral vessels and the graft vascular pedicles. Immunosuppression starts as quadruple induction therapy for 3 days. Subsequently it is reduced to a two-drug maintenance protocol with cyclosporin A and azathioprine. We utilize radiography, digital subtraction angiography, duplex sonography, scintigraphy, and arthroscopy for graft monitoring. Six months after transplantation the osteotomies were bridged with callus, and the patients were completely mobilized. The motion in the transplanted knee joint ranges from complete extension to 110 degree flexion.

Adolescent↗
PubMed1998

Importance of arterial blood supply to the femur and tibia for transplantation of vascularized femoral diaphyses and knee joints.

The role of the periosteal and intraosseous blood supply to the femur and the proximal tibia was investigated to improve the operating technique for transplantation of allogenic vascularized femoral diaphyses and knee joints in humans. Altogether 48 limbs were injected with gelatin, red latex milk, or Revertex and macroscopically prepared; 41 limbs were studied for the variation and division of the truncus profundo-circumflexus. In 200 femurs and 200 tibias the location of the nutrient foramen was determined. The arteries supplying the periosteum of the distal femur and the proximal tibia have defined nutritive areas. The following technique should be followed: If the femoral artery alone is prepared as the vascular pedicle, the optimal section for resection of the femur in knee joint transplantations is 6 to 12 cm above the level of the femur condyles and 5 to 7 cm below the tibial plateau. For the transplantation of femoral diaphyses, the deep femoral artery can be used if the lateral femoral circumflex artery is protected. The Proximal line of resection is defined between the greater and lesser trochanter. For shorter grafts one must consider the number and location of nutrient foramens. For longer grafts the distal branches of the femoral artery must be respected as the intraosseous blood supply reaches distally down to the level of about 8 cm above the femoral condyles. In all these operations of the variation of the truncus profundo-circumflexus and the trifurcation of the popliteal artery must be considered.

Aged↗
PubMed1998

Interlocking compression nailing: a report on 402 applications.

Nailing techniques have changed tremendously in recent years. One significant development has been the interlocking compression nail (ICN) which provides active interfragmentary compression. Apart from its beneficial effect in the treatment of acute fractures, allowing early weight-bearing and mobilization of the patient the ICN is useful in many types of revision operations: resection and stabilization of pseudarthroses without cancellous bone grafts, corrective operations of malalignments through a minimally invasive technique, as well as the readaptation of the resection sites in arthrodeses. Between April 1993 and September 1996, 402 consecutive applications of an ICN were followed prospectively to evaluate the practibility and reliability of the system. A special focus was placed on the active compression device. Along with 153 acute fractures, 112 non-unions and 41 cases of malalignment were treated; 96 arthrodeses were performed. Even for difficult courses of healing only a low complication rate was observed, and a remarkably high percentage was managed successfully.

Adult↗
PubMed1998

Allogeneic vascularized transplantation of human femoral diaphyses and total knee joints--first clinical experiences.

This article has presented the preliminary results of three patients who received vascularized allogeneic femoral diaphyses and three patients having undergone vascularized transplantation of fresh and perfused total human knee joints. The large osseous defects in the femora followed osteomyelitis and chondrosarcoma. The three knee joints were lost due to various trauma mechanisms. All grafts were harvested within 25 hours from multiorgan donors perfused with 4 L of UW solution. All osteosyntheses were performed employing intramedullary nails. Vascular pedicles of the grafts were anastomosed end-to-side to the superficial femoral artery and vein in the adductorial canal of the recipient thigh. Immunosuppression was based mainly on two drugs: CyA and AZA. Perfusion of the grafts was demonstrated by DSA, and bone metabolism in the graft by SPECT scintigraphy. Six months after the operation all osteotomies demonstrated callus formation and osseous consolidation in conventional radiographs. Biopsies of the grafted bone revealed intact osteocytes, and arthroscopy of the transplanted knee joints demonstrated intact synovial, chondral, and ligamentous structures. From the surgical aspect, the vascularized transplantation of the femoral diaphyses and total knee joints is technically feasible. The main problems are immunologic. All transplantations were performed with respect to ABO compatibility, but with a large HLA mismatch. Therefore, acute and chronic rejection crises were observed. In total synovial joints, lifelong immunosuppression of graft recipients seems to be currently unavoidable.

Adult↗
PubMed1998

[As lumbago treated, delayed diagnosis of large intestine perforation with extremely severe peritonitis--case report with focus on the value of diagnostic laparoscopy].

We report on a colon perforation with peritonitis which remained clinically undetected until the 4th day post trauma although the patient suffered from lumbalgia-like symptoms. He then developed an acute abdomen with sudden onset, being caused by a sigmoidal rupture and a consecutive diffuse peritonitis. A colon resection was performed according to the Hartmann procedure. Almost 36 revisions were necessary due to necrosis and perforation. Having treated the peritonitis successfully it was possible to close the abdomen and to remove the stomata. The case is discussed in relation to standard diagnostic procedures while a special interest is focused on the usage of sonography, explorative laparoscopy and laparotomy. We finally introduce the algorithm being applied to similar cases at our trauma center.

Abdomen, Acute↗
PubMed1997

Allogeneic vascularized grafting of a human knee joint with postoperative immunosuppression.

In this paper we report the first successful allogeneic vascularized transplantation of a fresh and perfused human knee joint. A 17-year-old male had lost his knee in a motorvehicle accident. The graft was harvested from a multiorgan donor, perfused with 41 UW solution and transplanted within 21 h. Osteosyntheses were performed employing intramedullary nails. Immunosuppression was based mainly on two drugs: cyclosporin A and azathioprine. Five months after the operation the patient is fully mobilized, and the graft perfusion still intact. Osteotomies of the femur and tibia demonstrate callus formation and osseous consolidation.

Accidents, Traffic↗
PubMed1997

Immunological transformations in the recipient of grafted allogeneic human bone.

Twenty-one patients received allogeneic human bone grafts following deep freezing according to various orthopaedic indications. The HLA antigens of all donors and recipients had been determined preoperatively, and grafting was performed without any respect to the HLA match. The immunological follow-up of the recipients was managed by two different methods: MLC (mixed lymphocyte culture) and MAILA (monoclonal antibody-specific immobilisation of lymphocyte antigens). No immunosuppression was performed. The follow-up lasted up to 6 years. Allogeneic grafting of human cancellous bone induces specific immunological reactions in the recipient. The consequences of these observations are: (1) allogeneic bone grafting may induce second-set reactions following subsequent blood transfusion, tissue grafting or organ transplantation; (2) transplantation of fresh, perfused, vascularised allogeneic bone or joint may become a therapeutic approach in the near future. Then the employment of standard immunosuppressive protocols will be mandatory in order to fight acute rejection of the graft.

Adolescent↗
PubMed1997

The arterial blood supply of the human patella. Its clinical importance for the operating technique in vascularized knee joint transplantations.

The architecture of the arteries supplying the patellar rete was examined in 14 anatomic specimens in order to develop an optimized operating technique for knee joint transplantation. The specimens were fixed in Jores Solution and exarticulated from the hip joint. The lower limbs were injected with Berliner-Blau-Gelatin, and the arteries were dissected macroscopically. Five to six main arteries entered the patellar rete at 1, 3, 5, 7 and 11 o'clock forming an arterial circle. These arteries were the same main arteries which supply the distal end of the femur and the proximal part of the tibia. From an anatomic perspective, they provide the complete arterial blood supply to a whole knee joint being transplanted including the patella. Based on these anatomic results, we transplanted two allogenic vascularized human knee joints preserving the patella, the capsule, and the patellar ligament. Up to six months after surgery we demonstrated the perfusion and viability of all three transplanted bones, particularly the patella, by 99mTc DPD scintigraphy. We compared these findings with knee joint arthroscopy and with histologic results from biopsies taken from the patella. The postoperative examinations clearly indicated the viability of the transplanted patella employing this new operating technique. The results of the entire study demonstrate that it is technically feasible to transplant a whole knee joint which remains clinically viable.

Adult↗
PubMed1997

[The osteosynthesis implant and early postoperative infection: healing with or without removal of the material?].

This prospective study served as a quality control of a revision concept for case of post-traumatic infection following open reduction and internal fixation in fracture treatment. It is based on clinical and microbiological criteria and has two aims: (1) eradication of the infection and avoidance of development of chronic osteitis; (2) maintenance of internal fixation, if possible. Thirty-four patients were recruited in this study. Surgical revisions were performed according to a consistent concept (debridement, irrigation, local chemotherapy, drainage) in defined time intervals (2 days). The operation site had to be bacteriologically clean after four revisions. Otherwise, the implant had to be removed. Both aims were reached in 11 cases: management of infection with maintenance of internal fixation. In 23 cases the implant material had to be removed. Nevertheless the infection was eliminated in all these patients without exception. The following risk factors for mandatory implant removal were evaluated: diabetes, arteriosclerosis, alcoholism, nicotine. This revision concept helps in the management of acute postoperative osteitis following ORIF in fracture treatment and in avoiding the development of chronic osteitis.

Adolescent↗
PubMed1997

Biomechanical evaluation of a bioresorbable PLA dowel for arthroscopic surgery of the shoulder.

Metallic implants in the reconstructive surgery of the shoulder joint can lead to certain complications. Therefore, a small bioresorbable dowel made of PLA has been developed for arthroscopic refixation of the glenoid labrum. Biomechanical tests employing in vitro degradation should confirm the implant's viability before starting the clinical application. Pull-out experiments of sutures fixed with these dowels were performed. The bioresorbable implant fulfilled the mechanical expectation in its time-dependent stability under realistic conditions by far. A reliable fixation of sutures by the implant in clinical situations can be widely guaranteed with these experimental results.

Arthroplasty↗
PubMed1996

Assessment of oxygen radicals during kidney transplantation--effect of radical scavenger.

In the present study, levels of free oxygen radicals, generated in the very early period of reperfusion during human kidney transplantation, were assessed by determination of malondialdehyde (MDA) levels using a high-pressure liquid chromatography (HPLC) method. Renal blood samples were obtained during reperfusion by intraoperative cannulation of the renal vein. Simultaneously, systemic MDA levels were determined. Furthermore, local and systemic levels of interleukin 6 (IL-6), tumor necrosis factor (TNF) receptors, p55 and p75, and vitamin E were measured. In a second group of patients, 500 mg of ascorbic acid were given prior to reperfusion. Renal MDA levels in the control group were always higher compared to systemic levels. IL-6 showed a marked increase shortly after reperfusion in the renal blood. In the scavenger group there was a diminution of these effects. TNF receptor levels and vitamin E remained largely unchanged. The results of this pilot study demonstrated clinically the moderate production of reactive oxygen species and the liberation of IL-6 shortly after reperfusion of human transplanted kidneys. Furthermore, the modulating effect of a radical scavenger on these effects was shown.

Adult↗
PubMed1996

Anatomic bases of a vascularized allogenic knee joint transplantation: arterial blood supply of the human knee joint.

The vitality of a graft in a vascularized allogenic knee joint transplantation in humans will depend strongly on maintaining the arterial blood supply to the bone. As can be demonstrated in injected specimens on cadavers, only periostal aa. are important to ensure the blood supply of the human knee joint. The main arteries have defined nutritive areas. According to our results access to the vessels should most probably be conducted from the dorsal side of the knee. During the explantation the popliteal a. should be ligated proximally as high up as possible and distally just above its trifurcation. The articular branch of the descending genicular a. of both the donor and the recipient can be ligated because of a rich anastomotic network. The medial and lateral inferior genicular aa. of the donor should be ligated ventrally as far forward as possible. One should, above all, preserve the medial inferior genicular a. of the donor in order not to endanger the medial part of the distal segment of the graft. If an operation is to be performed according to the results of our anatomical studies, vascularized allogenic knee joint transplantations should be successful from an anatomical point of view.

Femur↗
PubMed1996

Postoperative irradiation treatment and bioresorbable implants in orthopaedic surgery: an experimental in vitro study.

The influence of applied radiation on the degradation of a polyglycolide (PGA) test specimen was studied in vitro. There was no significant difference in the time-dependent degradation behaviour between the irradiated test specimen and controls. Mandatory irradiation of an operation site following surgery therefore does not contradict the employment of bioresorbable implants in orthopaedic surgery.

Absorption↗
PubMed1995

Biodegradable implants in traumatology: a review on the state-of-the-art.

Up to now the internal fixation of fractured bones and joints has been managed by metal implants. There are certain associated disadvantages: the mechanical properties of the metals are stronger than those of cortical bone ("stress-protection"); the removal of the implants requires a second operation; an increasing number of patients are confronted with problems of sensitivity to metal components of the implants, especially nickel. About 40 different biodegradable polymers, copolymers and composites have been developed as substitutes for metal implants in internal fracture fixation. The early experimental and clinical results demonstrate their limitations. From the current point of view, it is not possible to transfer the designs and assembling principles of metal implants in orthopaedic surgery to biodegradable polymers. The attempt to simply mimic metal implants in polymers is condemned to fail from the very beginning. This is a review of the literature and of our first 100 patients operated on using implants made of self-reinforced polyglycolide acid and polydioxanone. The main difficulty with the material is the loss of stiffness in a time interval which is not long enough to guarantee bone healing. The development of a sterile sinus over the site of implantation is a problem also reported by other groups. Certain additives have to be inserted into the polymers to make them visible on conventional X-radiographs. Despite these drawbacks, however, there are indications for the isolated or adjuvant implantation of biodegradable materials. They could be employed in the treatment of osteochondral fractures and other defined injuries. The available literature on these indications will be discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗