PubMed Health⌕ Search

Biomedical subjects

R Baumgart

Publications and source records attributed to R Baumgart.

At least 19 recordsLinked to original sources
PubMed2005

Systemic regulation of angiogenesis and matrix degradation in bone regeneration--distraction osteogenesis compared to rigid fracture healing.

Aim of this study was the investigation of systemic biochemical regulation mechanisms of bone regeneration by angiogenic and matrix-degrading enzymes during distraction osteogenesis compared to rigid osteotomy bone healing. Serum samples of 10 otherwise healthy patients with callus distraction for lower limb-lengthening and 10 osteotomy patients undergoing elective axis correction have been collected prospectively in a standardized time schedule before and up to 6 months after the procedure. At the end of the individual investigation period, concentrations of metalloproteinases (MMP-9, -13), tissue inhibitors of metalloproteinases (TIMP-1, TIMP-2) and the angiogenic factors angiogenin and VEGF have been detected by use of commercially available enzyme immunoassays. Results have been compared to our preliminary study on proMMP-1-3. In distraction osteogenesis, significantly elevated serum concentrations compared to baseline could be detected postoperatively for proMMP-1, MMP-9, TIMP-1, angiogenin and VEGF but not for proMMP-2, proMMP-3 or TIMP-2. In patients with rigid osteotomy healing, MMP-9, TIMP-1, TIMP-2, angiogenin and VEGF were significantly increased respectively. Comparison of both patient collectives revealed significantly higher increases of serum proMMP-1, VEGF and TIMP-1 in distraction patients during the lengthening period and significantly higher serum concentrations of TIMP-2 in late fracture healing period in osteotomy patients. Serum levels of MMP-13 were below the lowest standards, and therefore quantitative analysis was not possible. Bone regeneration in distraction osteogenesis and rigid osteotomy healing is accompanied by systemic increase of matrix-degrading and angiogenic factors in a certain time course and quantity. This might reflect biochemical regulation of local bone healing in the circulation. ProMMP-1, VEGF and TIMP-1 seem to be key regulatory factors during distraction osteogenesis.

Adult↗
PubMed2005

[Central bone transport system optimizes reconstruction of bone defects. Results of 40 treatments].

BACKGROUND: This article describes the results, experiences, and advantages of a bone transport system with one single rope or a fully implantable distraction nail for the treatment of bone defects that totally avoids soft tissue cross traction. METHODS: 40 patients with bone defects were treated by central bone transport systems. 30 post-traumatic defects (12 aseptic, 18 post-septic) and 10 defects after resection of bone tumors (2 benign, 8 malignant). Thirty defects were located at the tibia and ten at the femur; the mean defect size was 10.1 cm; 36 central rope systems and 4 motorized distraction nails were used. The follow-up examination took place after an average of 2.4 years. RESULTS: All defects were totally bridged. The mean distraction time was 131 (57-208) days and the mean time of external fixation 283 (126-326) days. The time of partial load bearing was 466 (302-594) days and the healing index was 47 (33.1-60.4) d/cm. In 34 patients autologous bone grafting at the docking site was performed, and in 30 patients the external fixator was replaced by internal stabilization. The mean leg length discrepancy compared to the contralateral side was 4+/-3 mm, and the leg axis deviation from the center of the knee joint was 1.5+/-7.0 degrees . There were 1.8 complications per patient on average (15 pin tract infections with replacement, 2 premature consolidations). CONCLUSIONS: In contrast to conventional methods reduced pin tract infections offer better conditions for internal fixation. Control of length and axis can be optimized, immobilization of the patients is reduced, and the comfort of treatment is significantly improved.

Adolescent↗
PubMed2005

Reduction of high dislocation of the hip using a distraction nail before arthroplasty.

We report the case of a 22-year-old woman who underwent plate and screw fixation for a traumatic left acetabular fracture and fixation with cancellous screws for an associated femoral neck fracture. Two months later, the internal fixation became infected and was removed. This resulted in a painful high dislocation of the hip. We solved the problem with continuous soft-tissue distraction using a fully implantable motorised distraction nail in order to reduce the proximal femur prior to total hip arthroplasty. To our knowledge, this is the first time that reduction of a high dislocation of the hip has been performed using such a system.

Acetabulum↗
PubMed2005

The management of leg-length discrepancy in Ollier's disease with a fully implantable lengthening nail.

Ollier's disease is characterised by severe deformity of the extremities and retarded growth because of multiple enchondromas. For correction of deformity, the Ilizarov method has been used although it has many complications. A 17-year-old boy with Ollier's disease had a limb-length discrepancy of 17.4 cm, with a valgus deformity of the right knee and recurvatum of the femur of 23 degrees . He had undergone three unsuccessful attempts to correct the deformities by using external fixators. We used a fully implantable, motorised, lengthening and correction nail (Fitbone) to achieve full correction of all the deformities without complications. We decided to carry out the procedure in three stages. First, we lengthened the femur by 3.6 cm and the tibia by 4 cm. We then exchanged the femoral nail for a longer implant and achieved a further 6 cm of length. This reduced the shortening to 3.8 cm. When the boy has finished secondary school we will adjust the remaining discrepancy.

Adolescent↗
PubMed2004

Cartilage atrophy in the knees of patients after seven weeks of partial load bearing.

OBJECTIVE: It is currently unknown whether human cartilage properties change during short periods of partial load bearing. We used a post-ankle fracture model to explore whether changes in cartilage morphology occur in the knee under conditions of partial load bearing. METHODS: The knees of 20 patients with Weber type B and type C fractures were examined using magnetic resonance imaging. The first scan was obtained shortly (mean +/- SD 3.2 +/- 3.0 days) after the injury, and a second scan was obtained 7 weeks later (mean +/- SD 50.7 +/- 5.5 days). The morphology (mean and maximum thickness, volume, and surface area) of the patellar, tibial, and femoral cartilage was determined from coronal and axial magnetic resonance images (fat-suppressed gradient-echo). RESULTS: Between week 0 and week 7, the cross-sectional area of the quadriceps muscle was reduced by 11% (P< 0.001). Changes in the mean (+/-SD) cartilage thickness ranged from -2.9 +/- 3.2% in the patella to -6.6 +/- 4.9% in the medial tibia. No significant change in cartilage morphology of the contralateral knee was observed. CONCLUSION: Results of this study demonstrate that in a post-ankle fracture model of partial load bearing, cartilage morphology in all knee compartments is subject to significant change. Changes in the femorotibial joint exceeded those in the patella, whereas no change was observed in the contralateral knee. These findings raise the question of whether cartilage is mechanically less competent and particularly vulnerable after states of partial or complete immobilization.

Adolescent↗
PubMed2004

Influence of a mono-centric knee brace on the tension of the collateral ligaments in knee joints after sectioning of the anterior cruciate ligament--an in vitro study.

OBJECTIVE: To analyze the influence of knee bracing on the tension of the medial and lateral collateral ligaments in anterior cruciate ligament deficiency. DESIGN: The tension of the collateral ligaments in anterior cruciate ligament deficient knees was measured with and without knee bracing using an in vitro model. BACKGROUND: Anterior cruciate ligament deficiency increases the tension in both collateral ligaments at the knee joint. Therefore knee braces should reduce that tension increase. However, that effect has never been proven quantitatively. METHODS: After anterior cruciate ligament-transection, the forces of the medial (anterior/posterior part) and lateral collateral ligament were measured in ten fresh human cadaver knees at 0 degrees, 20 degrees, 40 degrees, 60 degrees, 80 degrees and 100 degrees of flexion, with and without application of a mono-centric knee brace. To quantify the ligament forces, strain gauges were fixed at the bony origins of the ligaments. RESULTS: Bracing led to a significant decrease of ligament forces (20-100 degrees: P < 0.0001) in the anterior part of the medial collateral ligament in all joint positions. In the posterior aspect, this effect was observed only at 40 degrees (P < 0.0001) and 80 degrees (P = 0.001) of flexion. In the lateral collateral ligament, bracing caused a strain reduction from 60 degrees to 100 degrees of flexion (P < 0.0001). Therefore a flexion angle dependent effect of knee bracing on the strain was seen in the posterior aspect of the medial and in the lateral collateral ligament in anterior cruciate ligament deficient knee joints. CONCLUSIONS: Application of a mono-centric knee brace leads to a significant position dependent reduction of collateral ligament tension after anterior cruciate ligament-rupture.

Anterior Cruciate Ligament Injuries↗
PubMed2004

[Central cable system--fully automatic, continuous distraction osteogenesis for the lengthening treatment of large bone defects].

Distraction osteogenesis involving bone transport enables the reconstruction of large bone defects. The main bone fragments are usually stablilised externally, an intermediate bone segment is separated and moved through the defect at a rate of about 1 mm/day. New high-quality bone is built up in the constantly enlarging osteotomy gap. A major problem associated with the method is the fact that the fixation pins are also moved over the same distance, and cut through the soft tissue, often resulting in painful pin tract infections and ugly scars. An automatic motorized bone transport system employing a single central cable now eliminates this problem. The system can be combined with any external fixateur, since the relevant implanted parts for bone transport are independent of the external stabilizer. The surgical procedure, which is easy on the patient, consists of bone segment separation, central cable fixation, and stabilisation of the main fragments, and requires the use of numerous special tools. The distraction itself results in significantly less soft tissue irritation and pain. Pin tract infections are rare, so that changeover to internal fixation after completion of bone transport carries little risk of infection. This article details the technical features of the stabilizing system and the transport and the control systems, and describes the clinical application in a patient.

Adult↗
PubMed2004

[Tractive force measurement in bone transport--an in vivo investigation in humans].

Bone transport applying the principle of distraction osteogenesis makes it possible to reconstruct long bone defects caused by trauma or resection of bone tumors. The method employing a central cable, developed in Munich, is especially suitable for such applications. The main bone fragments are stabilized by an external fixateur, and bone transport is effected with a single central cable fixed to the tip of the segment, and driven by an external, programmable motor. In 15 patients the tractive forces during the entire bone transport were measured with a strain gauge incorporated within the cable. On the basis of the force profiles characteristics normal bone transport (forces between 150-250 N) can be distinguished from a critical transport (forces > 250 N) with the risk of premature consolidation. There is some evidence that at a very high level of force, just before premature consolidation a very effective form of bone transport with good bone neoformation can be achieved. Transport systems employing a central cable allow this special form of distraction osteogenesis, since there is continuous force monitoring, and there is the option of employing the traction force as a control factor in a loop.

Adolescent↗
PubMed2002

Tension changes in the collateral ligaments of a cruciate ligament-deficient knee joint: an experimental biomechanical study.

BACKGROUND: The biomechanical changes in the cruciate ligament-deficient knee are still widely unexplained. By producing a model of cruciate ligament insufficiency in the knee joint, we wanted to provide an experimental explanation for the great amount of secondary injuries to the knee joint after conservative treatment of an anterior cruciate ligament rupture. METHODS: The forces exerted on the medial and lateral collateral ligament were measured in ten fresh human cadaver knees. While simulating muscle force and body weight, the ligamentous loading patterns were determined before and after the anterior cruciate ligament was transected. The specimens were moved in a special apparatus from 0 degrees extension to 100 degrees flexion. Strain gauges were used to measure the ligament forces. They were fixed at the bony origins and insertions of the examined ligaments. The method allowed all ligamentous and capsular structures to be kept intact, thereby creating nearly physiological conditions by simulating muscular strength and axial force. RESULTS: During the quasistatic measurements, the relative changes of the ligament forces were determined from one angle position to the next. The variability of these relative values were very small among the ten specimens. The method yielded reproducible ligament force data. The values obtained in the intact knee joints were markedly similar to those reported in the literature. Cutting the anterior cruciate ligament led to a general increase of the ligament forces on both collateral ligaments. CONCLUSION: Our results show excess stress of the main ligamentous stabilisers after anterior cruciate ligament transection. This is an explanation for the secondary injuries often seen after conservative treatment of anterior cruciate ligament rupture as a result of impaired knee biomechanics.

Adult↗
PubMed2002

Systemic regulation of distraction osteogenesis: a cascade of biochemical factors.

This study investigates the systemic biochemical regulation of fracture healing in distraction osteogenesis compared with rigid osteotomy in a prospective in vivo study in humans. To further clarify the influence of mechanical strain on the regulation of bone formation, bone growth factors (insulin-like growth factor [IGF] I, IGF binding protein [IGFBP] 3, transforming growth factor [TGF] beta1, and basic FGF [bFGF]), bone matrix degrading enzymes (matrix-metalloproteinases [MMPs] 1, 2, and 3), human growth hormone (hGH), and bone formation markers (ALP, bone-specific ALP [BAP], and osteocalcin [OC]) have been analyzed in serum samples from 10 patients in each group pre- and postoperatively. In the distraction group, a significant postoperative increase in MMP-1, bFGF, ALP, and BAP could be observed during the lengthening and the consolidation period when compared with the baseline levels. Osteotomy fracture healing without the traction stimulus failed to induce a corresponding increase in these factors. In addition, comparison of both groups revealed a significantly higher increase in TGF-beta1, IGF-I, IGFBP-3, and hGH in the lengthening group during the distraction period, indicating key regulatory functions in mechanotransduction. The time courses of changes in MMP-1, bone growth factors (TGF-beta1 and bFGF), and hGH, respectively, correlated significantly during the lengthening phase, indicating common regulatory pathways for these factors in distraction osteogenesis. Significant correlation between the osteoblastic marker BAP, TGF-beta1, and bFGF suggests strain-activated osteoblastic cells as a major source of systemically increased bone growth factors during callus distraction. The systemic increase in bFGF and MMP-1 might reflect an increased local stimulation of angiogenesis during distraction osteogenesis.

Adult↗
PubMed2002

[Measuring ligament elasticity of the knee joint--elasticity measuring strip and its alternatives].

Those techniques for measuring ligament tension at the knee joint that are most commonly cited and easiest to carry out are discussed. These include four techniques based on the use of strain gauges. Apart from the Omega transducer and the buckle transducer, there is also the tendon force transducer, and the application of strain gauges to the bony ligament insertion sites. Other indirect measuring methods considered are the mercury strain transducer and the Hall effect transducer. The parameter measured with all of these methods is fluctuating current or voltage, which is then correlated with ligament tension. Three direct measurements are also discussed: the separation distances of marked fibres of the ligaments, replacement of fibres by threads, and a load cell/bone plug construction. The measured value is equated with the effective change in ligament length.

Animals↗
PubMed1999

[The biological reaction in atrophic and hypertrophic pseudarthrosis of diaphysis of long bone. Causes and forms of appearance].

The grading of long-tubular-bone pseudarthrosis depends on the biological reaction or lack of reaction in pseudarthrosis or non-unions. Hypertrophic and oligotrophic pseudarthrosis belongs to biologically reacting non-unions, whereas non-reacting non-unions are necrotic pseudarthrosis and defective non-unions with partial decline or complete destruction of cortical substance. Pseudarthrosis is a serious disturbance or disorder within the regulation cycle in fracture healing, which consists of osteoregeneration, osteovascularization and stabilization. The causes and underlying reasons for disturbance of this regulation cycle are primarily massive destruction of the biological and functional very important unity of periost, cortical substance and medullary space. This can occur from trauma, but it happens more often from surgical procedures that do not take the biological principles of bone-healing into account. Surgical strategies and interventions that respect the importance of periosteal tissue, cortical tissue and medullary space do fill the biological principles of fracture-healing and fracture union.

Animals↗
PubMed1999

[Fully implantable intramedullary distraction nail in shortening deformity and bone defects. Spectrum of indications].

Since the first clinical experiences with the fully implantable programmable distraction nail nearly ten years ago, the system has been improved in Munich and meanwhile used in 26 patients. During the first 10 cases there has been highest interest in the reliability of the system, while in the following the expansion of indications was more important. At the thigh a good indication beside shortening is the combination of shortening and axis deviation, even if the center of deviation is located near to the knee joint in the supracondylar area. According to preoperative planing the deformity correction can be done acutely while the lengthening procedure follows postoperatively automatically at night-time. If the stabilization with an intramedullary nail is possible, large bone defects can be treated by bone transport using this system also. The fully implantable intramedullary nail has proved its variable functions in cases of large bone defects combined with shortening of the femur. The system is able to perform the bone transport at first and the lengthening procedure automatically without any further operation thereafter.

Accidental Falls↗
PubMed1998

[Indications and technique of bone cutting].

For cutting bones different tools and techniques are available. The question which method is most advantageous depends on the basic surgical concept, the location of the bone cut and the choice of the subsequent implant. The biological activity of the anatomical site of the cut determines how much the tissue needs to be protected, taking into consideration the vascularity of the bone and avoiding heat transfer. The surgical approach depends on the implant and should be used also for the bone cut. Specific indications are given for the oscillating saw, the Gigli saw, the osteotome, drill holes and the medullary saw.

Equipment Design↗
PubMed1998

[Primary shortening--secondary lengthening. A new treatment concept for reconstruction of extensive soft tissue and bone injuries after 3rd degree open fracture and amputation of the lower leg].

The main problem in major limb replantation--especially of the lower extremity--is an extensive bone- and soft-tissue loss. The traditional replantation concept tries to preserve the initial limb length; only a small shortening is accepted. To avoid a more extensive shortening, often insufficient debridement at the time of replantation is carried out. After successful revascularisation, bone and soft-tissue defects will be reconstructed according to the principles of staged reconstruction. Especially segmental nerve defects of more than one major peripheral nerve and severe skin and muscle loss necessitate extensive secondary grafting procedures. This often leads to a prolonged hospitalisation and a high complication rate. In 1951, Lorenz Böhler described the deliberate extremity shortening as a method of therapy in segmental combined bone-soft-tissue defects of the extremities. No additional surgical procedure were necessary to treat the soft tissue defect. A functional but shortened extremity was the result. With Ilizarov's principle of callus distraction he proved in an extensive experimental and clinical study the possibility to lengthen extremities without functional damage up to 20 cm. A new reconstruction concept--"concept of primary shortening with secondary limb lengthening"--for the treatment of amputation and/or amputation-like injuries was created by combining both principles mentioned above. At the time of replantation (reconstruction), deliberate shortening is carried out in order to reduce soft-tissue and/or bone defect or to enable primary nerve repair. Moreover, the aggressive debridement leads to a reduction of the local complication risk (wound healing disturbance, infection) and the potential systemic complications (crush-syndrome, ischemia-reperfusion-syndrome) after revascularisation of a large tissue bloc. Six to twelve months after replantation, secondary limb lengthening is started using an external or internal (= programmable intramedullary nail) distraction device. Since 1985, twelve patients (six macroamputations and six third-degree open fractures of the lower leg) have been treated using the "concept of primary shortening with secondary limb lengthening". Indications, operative technique, and results are shown and discussed, comparing this new concept to the traditional "concept of staged length-reconstruction" with extensive free tissue reconstruction and secondary nerve grafting.

Adult↗
PubMed1997

[Possibilities of osteotomy. Osteotomy and corticotomy techniques].

Corrective measures on the bone undertaken after the fusion of epiphyses are only possible through an initial break in its continuity. This paper deals with the different methods of osteotomy available to the orthopaedic or trauma surgeon. After introducing the terminology of the so-called "osteotomy", the vascularity of the bone, special features of the various osteotomy site, the different indications, and particular details of the operative procedures are discussed. Special emphasis is placed on minimally invasive techniques and osteotomies in the framework of callus distraction. In addition to established procedures a new sawing technique for the Küntscher's closed osteotomy is described.

Bone Lengthening↗
PubMed1997

A fully implantable motorized intramedullary nail for limb lengthening and bone transport.

This article describes an intramedullary nail that contains a fully implantable motorized programmable sliding mechanism for limb lengthening and bone transport that reduces the risk of infection, discomfort, and scarring usually associated with the external fixators used for the same purpose. Twelve patients were treated surgically with the new system. Eleven patients had unilateral femur shortening between 3 and 7.5 cm, and one patient had a 12-cm defect after tumor resection. In all patients with femur shortening the leg length discrepancy was corrected completely. In the case of bone defect the segment transport worked well without any problems. There was no infection and no axial deformity. Immediately after chemotherapy, delayed bone formation was seen. In two early cases of limb lengthening a technical problem led to replacement of the motor.

Adolescent↗