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Wolfgang Rüther

Publications and source records attributed to Wolfgang Rüther.

15 recordsLinked to original sources
PubMed2006

Leflunomide increases the risk of early healing complications in patients with rheumatoid arthritis undergoing elective orthopedic surgery.

The aim of this object is to study whether treatment with biological or leflunomide increases the risk of wound-healing complications after elective orthopedic surgery. Between March 2002 and September 2003, 201 patients participated in this study with the following inclusion criteria: (a) Rheumatoid arthritis (RA) or psoriatic arthritis (psA), (b) therapy with: MTX, leflunomide, etanercept, infliximab, adalimumab, anakinra, (c) undergoing elective orthopedic surgery. The incidence of early postoperative wound-healing complications was compared among the different groups. In comparison with patients who received MTX therapy (n = 59), the risk of postoperative wound-healing complications in patients undergoing leflunomide therapy (n = 32) was significantly higher: 13.6% in the MTX group, 40.6% in the leflunomide group (P = 0.01). It is recommended that leflunomide medication for patients with RA undergoing elective orthopedic surgical procedure is interrupted preoperatively to reduce the risk of early wound-healing complications or infections.

Adult↗
PubMed2006

Sequential changes in vessel formation and micro-vascular function during bone repair.

BACKGROUND: Angiogenesis, the process of new vessel formation from a pre-existing vascular network, is essential for bone development and repair. New vessel formation and microvascular functions are crucial during bone repair, not only for sufficient nutrient supply, transport of macromolecules and invading cells, but also because they govern the metabolic microenvironment. Despite its central role, very little is known about the initial processes of vessel formation and microvascular function during bone repair. METHODS: To visualize and quantify the process of vessel formation and microvascular function during bone repair, we transplanted neonatal femora with a substantial defect into dorsal skin-fold chambers in severe combined immunodeficient (SCID) mice for continuous noninvasive in-vivo evaluation. We employed intravital microscopic techniques to monitor effective microvascular permeability, functional vascular density, blood flow rate and leukocyte flux repeatedly over 16 days. Oxytetracyclin and v. Kossa/v. Giesson staining was performed to quantify the calcification process in vivo and in vitro. RESULTS: Development of a hematoma surrounding the defect area was the initial event, which was accompanied by a significant increase in microvascular permeability and blood flow rate. With absorption of the hematoma and vessel maturation, permeability decreased continuously, while vascular density and tissue perfusion increased. Histological evaluation revealed that the remodeling of the substantial defect prolonged the in-vivo monitored calcification process. INTERPRETATION: The size of the initial substantial defect correlated positively with increased permeability, suggesting improved release of permeability-inducing cytokines. The unchanged permeability in the control group with boiled bones and a substantial defect corroborated these findings. The adaptation to increasing metabolic demands was initially mediated by increased blood flow rate, later with increasing vascular density through increased tissue perfusion rate. These insights into the sequence of microvascular alterations may assist in the development of targeted drug delivery therapies and caution against the use of permeability-altering drugs during bone healing.

Animals↗
PubMed2006

Survival analysis and longterm results of elbow synovectomy in rheumatoid arthritis.

OBJECTIVE: To evaluate longterm results and survival rate of open synovectomy of the elbow joint in patients with rheumatoid arthritis (RA). METHODS: Between 1986 and 2000, synovectomy of the elbow was performed on 103 joints in 92 patients with RA. Eighty-five joints were included in this study. Mean age at time of surgery was 52 years (range 13 to 62 yrs). On 13 elbows with Larsen stage I and II disease, early synovectomy preserving the radial head was performed; in 72 cases with Larsen stage III and IV, late synovectomy with radial head resection was necessary. RESULTS: In early synovectomy, one joint received prosthetic joint replacement and 2 joints underwent resynovectomy a mean of 9 years after primary surgery. The survival rate (no further operations) was 91% after 5 years and 78% after 10 years. In late synovectomy, 16 elbow joints were operated again a mean of 4.6 years after primary surgery (10 prosthetic joint replacements, 2 resection interposition arthroplasties, 4 resynovectomies). Survival rate was 82% after 5 years and 66% after 10 years. Sixty-one elbows were examined clinically at a mean followup period of 8.7 years (range 2.8-17.3 yrs). There was a significant improvement of the Morrey score at followup, especially due to effective relief of pain. Improvement of joint motion was seen in late synovectomy for pronation and supination. The mean preoperative Larsen stage was 3.11, which decreased significantly to 3.66 at followup. CONCLUSION: Our findings suggest that synovectomy is a safe and effective procedure in differential treatment of RA of the elbow.

Activities of Daily Living↗
PubMed2005

Stimulation of implant fixation by parathyroid hormone (1-34)-A histomorphometric comparison of PMMA cement and stainless steel.

Whereas continuous exposure to PTH results in bone resorption, PTH administration at intermittent doses results in bone formation by increasing osteoblast number and activity. PTH leads to faster fracture repair and better fixation of orthopaedic implants in animal models. The present study evaluates if PTH is able to increase the contact surface between bone and implant and whether the effect of PTH is dependent on implant material characteristics. The implants were made as rods, either of stainless steel or Palacos R bone-cement. The steel rods had a surface roughness of R(a) 0.1 microm and the cement rods R(a) 2.2 microm. In 40 adult male rats, one cement rod was inserted in the left tibia and one steel rod in the right tibia. After implantation, the rats were divided into groups by random. One group was injected three times a week with human PTH (1-34) at a dose of 60 microg/kg BW/injection. The second group was injected with the vehicle only. Both groups were then divided into groups for 2 and 4 weeks time till tibial harvest. The tibial segments around the hole of the rods were then prepared by standard histological techniques. The linear tissue surfaces, that had been in contact with the surface of the rod, were analyzed in a blind fashion. PTH increased the bone contact fraction compared with the vehicle in the steel group from 7.4 (SD 7.6) to 21.1 (SD 10.7) % after 2 weeks and from 9.8 (SD 8.1) to 47.1 (SD 13.3) % after 4 weeks. In the cement group PTH increased the contact index again compared with the vehicle from 7.8 (SD 10.2) to 53.6 (SD 26.3) % already after 2 weeks and from 14.3 (SD 15) to 65.6 (SD 15.7) % after 4 weeks. The bone trabeculae adjacent to the implant had become fewer and thicker after the treatment with PTH (1-34), with an increase of the bone mass in the area next to the bone-implant-interface. The earlier onset of PTH effects in the rougher cement group suggests that intermittent PTH treatment might lead to an increased micro-interlock between implant and bone, and might therefore be considered as a possible drug to enhance incorporation of orthopedic implants.

Animals↗
PubMed2005

Long-term observation reveals time-course-dependent characteristics of tumour vascularisation.

Functional properties of tumour vasculature influence the process of metastasis and play a role in generating a heterogeneous metabolic microenvironment, which contributes to genetic instability and inefficiency of tumour therapies. Morphological and functional properties of tumour vasculature may vary from tumour onset to late-stage disease. The aim of this study was to identify the dynamic alteration in tumour microcirculation in a chronic observation model. Invasively-growing, non-disseminating, green fluorescent protein transfected, human bone marrow derived endothelial cells, were implanted into cranial windows of severe combined immunodeficient mice. Intravital fluorescence microscopy was performed over a period of 85 days to measure permeability, leucocyte-endothelial interaction (LEI) and tissue perfusion rate as functional parameters. Vessel density, branching pattern and scanning electron microscopy were monitored as morphological parameters. Concordant with an increasing count of transendothelial pores, the results show that the initial event following tumour cell implantation was a significant increase in the permeability of pre-existing vessels. The variations in newly formed vessels were characterised by sequentially-occurring functional and morphological alterations with the development of characteristics typical of tumour vessels, such as increased count of trifurcations and variation in vessel calibre by more than 100%. In parallel with the increasing vessel volume per area, the tissue perfusion rate increased until day 61. It is concluded from the step-specific sequential functional and morphological alterations that the efficiency of adjuvant therapies depends not only on their intrinsic efficiency but also on the timing of their initiation.

Animals↗
PubMed2004

Biomechanical analysis of transpedicular screw fixation in the subaxial cervical spine.

STUDY DESIGN: An in vitro biomechanical study to compare 2 different dorsal screw fixation techniques in the cervical spine with respect to primary stability and stability after cyclic loading. OBJECTIVES: To investigate if the biomechanical stability is better in pedicle screw or in lateral mass fixation. SUMMARY OF BACKGROUND DATA: In patients with poor bone quality who require multisegmental fixations, the current dorsal stabilization procedures in the subaxial cervical spine using lateral mass screws are often insufficient. Cervical pedicle screw fixation has been suggested as an alternative procedure, but there are still limited data available on the biomechanical differences between pedicle screw and lateral mass fixation. METHODS: A severe multilevel discoligamentous instability was created in 8 human cervical spine specimens (C2-C7). Dorsal stabilization was performed with the assistance of computer navigation (SurgiGate, Medivison, Switzerland) using either lateral mass or pedicle screw fixation. In the first part of the study, primary stability was measured by means of a multidirectional flexibility test. Then, specimens were divided into 2 groups, randomized for bone mineral density. Cyclic loading was applied with sinusoidal loads in flexion/extension (1000 cycles, +/-1.5 Nm, 0.1 Hz). Mechanical behavior of the specimens was determined by a flexibility test before and after the application of cyclic loads. Data analysis was performed by calculating the ranges of motion, and statistical differences were determined with the t test for group comparison. RESULTS: Pedicle screw fixation showed a significantly higher stability in lateral bending (pedicle screw range of motion 0.86 +/- 0.31 degrees; lateral mass range of motion 1.43 +/- 0.62 degrees; P = 0.037). No significant differences were seen in flexion/extension and axial rotation. After cyclic loading, the decrease in stability was less with pedicle screw fixation in all load directions. Differences in the decrease of stability were statistically significant in flexion/extension (pedicle screw 95.4 +/- 9.4%; lateral mass 70.5 +/- 9.8%; P = 0.010) and lateral bending (pedicle screw 105.3 +/- 5.0%; lateral mass 84.2 +/- 13.6%; P = 0.046), whereas there was no significant difference in axial rotation. CONCLUSIONS: The major finding of the current study was the higher stability of pedicle screws over lateral mass fixation with respect to primary stability and stability after cyclic loading. From a biomechanical point of view the use of pedicle screws in the subaxial cervical spine seems justified in patients with poor bone quality and need for multisegmental fixation.

Adult↗
PubMed2004

Surface replacement of the humeral head in rheumatoid arthritis.

INTRODUCTION: The concept of a newly developed cup arthroplasty (Durom Cup) involves the replacement of the destroyed joint surface of the humeral head with minimal bone resection. In cases of additional massive cuff tear, the cup can be placed in a more valgic position to articulate with the glenoid and the acromion. The aim of this prospective study was to evaluate the results of this surface replacement as a hemiarthroplasty in rheumatoid arthritis. MATERIAL AND METHODS: Forty-five Durom Cups in 39 patients (30 women, 9 men) with rheumatoid arthritis were evaluated preoperatively and every 3 months postoperatively. Their average age was 62.7+/-12.3 years and the average follow-up 45.1+/-11.6 months with a minimum of 36 months. Concerning the cuff, 15 shoulders had an intact cuff (group A), 18 shoulders a partial tearing or a repaired rotator cuff (group B), and 12 shoulders a massive cuff tear (group C). The Constant Score was used, and the cups were examined radiologically. RESULTS: In group A rheumatic shoulders, the Constant Score increased from 21.5+/-9.6 points preoperatively to 66.1+/-9.8 points at 36 months postoperatively; in shoulders of group B, from 19.6+/-9.7 points preoperatively to 64.9+/-9.6 points at 36 months postoperatively; and in shoulders of group C, from 17.5+/-8.7 points to 56.9+/-9.8 points at the latest follow-up examination. All shoulders were pain-free at the latest examination. No complications, component loosening or changes of cup position were observed. CONCLUSION: The results of the Durom Cup are encouraging. In shoulders with additional massive cuff tear, the limited goal criteria were always achieved. Therefore, cup arthroplasty is a good alternative to other kinds of shoulder endoprostheses in rheumatic shoulders with and without massive cuff tear.

Aged↗
PubMed2003

High migration rate of two types of threaded acetabular cups.

INTRODUCTION: Survivorship analysis was performed on 479 Link V-type threaded cups and on 110 modified V-type Bad Bramstedt cups (a modification of the Link V-type cup since 1993 with a smaller primary coil) to evaluate the effect of the modifications. MATERIALS AND METHODS: Indication for hip arthroplasty with a Link V-type cup was an inflammatory arthritis in 310 patients, osteoarthritis in 138 patients and dysplastic hip joints in 31 patients. The average follow-up was 8.6+/-3.2 (range 3.0-15.2) years. The 110 modified V-type Bad Bramstedt cups had a mean follow-up period of 4.5+/-0.7 (range 3.0-5.9) years, including 49 with inflammatory arthritis, 49 with osteoarthritis and 12 with dysplastic hip joints. To evaluate the migration rate and radiolucent lines, radiographical examination according to the method of Nunn et al. and Delee and Charnley was performed on 264 Link V-type cups with a mean follow-up period of 8.2+/-2.7 years and 59 modified V-type Bad Bramstedt cups with a mean follow-up period of 4.6+/-0.7 years. Relevant parameters influencing cup migration were analysed. RESULTS: The cumulative survival rate of the former Link V-type acetabular cup was 94.5% after 5 years, 88.1% after 10 years and 70.2% after 15 years. The Bad Bramstedt cup showed a 5-year survivorship rate of 97.9%. Migration of more than 3 mm or tilting of the cup greater than 5 degrees was found in 73% of the former type and in 39% of the modified cup. Radiolucent lines greater than 2 mm and detectable in two zones appeared in 6.4% of the former Link V-type and in 1.7% of the Bad Bramstedt cup design. Among the influencing factors analysed, length of follow-up and primary cup positioning showed a significant correlation to cup migration. CONCLUSION: The modification of the Link V-type cup showed no satisfactory improvement in cup migration. Therefore, both threaded cups were abandoned in favour of cementless press-fit cups.

Acetabulum↗
PubMed2003

Bilaterally increased VEGF-levels in muscles during experimental unilateral callus distraction.

Angiogenesis is essential for wound healing and proliferative processes such as bone formation and repair. Since increased expression of the vascular endothelial growth factor (VEGF) stimulates bone formation, it can be hypothesized that surgical procedures leading to a systemic increase of VEGF for instance during wound healing, influence enchondral ossification processes and might be responsible for observed growth phenomena during callus distraction. To study the mechanisms of angiogenesis in soft tissue during unilateral callus distraction, lengthening of the right tibia was performed in 12 beagles. After osteotomy, application of a ring fixator and after five latency days, distraction was started for 25 days. A control group of four additional beagles underwent no surgical procedure. Subsequent to the distraction period (Group A), muscle samples from six beagles were taken from the distracted side (ds) and the contralateral non-distracted side (n-ds), six beagles underwent an additional consolidation period of 25 days (Group B). Samples were analyzed for VEGF, VEGFR-1 and VEGFR-2 mRNA expression using real-time PCR and protein expression using Western Blot analysis. Muscles from both extremities showed significantly increased expression of VEGF and its cognate receptors VEGFR-1/2. Expression decreased significantly after the consolidation period, whereby the level at the non-distracted side decreased more than the level at the distracted side. Interestingly VEGF and VEGFR-1 levels at the non-distracted side were significantly higher than at the distracted side. In contrast VEGFR-2, the receptor that mediates endothelial cell proliferation, showed higher levels at the distracted than at the non-distracted side. These findings indicate that callus distraction results not only in locally increased expression of VEGF and its receptors, but leads also to increased VEGF and VEGFR-1/2 levels at distant sides and might therefore be responsible for the observed growth phenomena during callus distraction.

Animals↗
PubMed2003

Microvascular alterations in diabetic mice correlate with level of hyperglycemia.

Vascular alterations are the most common causes of morbidity and mortality in diabetic patients. Despite the impact of endothelial dysfunction on microcirculatory properties, little is known about the endothelial cell alteration during the development of diabetes and its correlation to the metabolic situation. For that reason we continuously monitored in vivo functional and morphological alterations of the microvasculature in hyperglycemic and hyperinsulinemic transgenic UCP1/DTA mice with brown fat deficiency, using a dorsal skin-fold chamber preparation and fluorescence microscopy. UCP1/DTA mice showed a dramatic decrease in vascular density due to a remarkable reduction of small vessels. Vascular permeability and leukocyte endothelial interactions (LEIs) significantly increased. The extent of vascular alteration correlated with the extent of metabolic dysfunction. Decreased tissue perfusion observed in UCP1/DTA mice might play a role in impaired wound healing observed in diabetes. The increased permeability in subcutaneous tissue may serve as predictor of vascular changes in early stages of diabetes. The increased LEI and serum tumor necrosis factor-alpha levels, which mirror the inflammatory process, support the growing evidence of the inflammatory component of diabetic disease. The results suggest that anti-inflammatory strategies might be able to prevent vascular deterioration in early stages of diabetes. Further investigations are required to evaluate the benefit of such therapeutic strategies.

Animals↗
PubMed2002

The thrust plate prosthesis in patients with aseptic osteonecrosis of the femoral head.

BACKGROUND: The thrust plate prosthesis (TPP) is an implant with a metaphyseal fixation at the proximal femur that transmits the load forces of the hip onto the femoral neck. The osseous incorporation of the TPP and the adaptation of the bone to this force transmission depend on the bone quality, which is reduced to minor vitality and stability in patients with osteonecrosis of the femoral head. Depending on the etiology of the femoral head necrosis, the TPP might lead to early failures. METHODS: In a prospective study, 63 patients with 72 cementless TPP due to femoral head osteonecrosis were examined. A clinical and radiological evaluation was performed preoperatively, 3 and 6 months postoperatively, and every year thereafter. The average follow-up period was 4.8+/-1.3 years with a minimum of 3 years. The pathogenesis of femoral head necrosis included alcoholism (n=19), subsequent to renal transplantation (n=11), during cortisone therapy of other dyscrasia (n=9), preceding a polychemotherapy (n=4), diabetes (n=3), sickle cell anemia (n=1), and idiopathic osteonecrosis (n=25). RESULTS: The Harris Hip Score increased continuously from 50.0 points beyond 79.8 points after 3 months to 86.8 points within the 1st year, and subsequently remained stable at this level. Revision was necessary in six cases (8.3%). Of these, three had an aseptic loosening of the implant: 2 cases with renal transplantation and 1 of alcoholism with an extension of the necrotic area to the seating of the TPP. The other three patients showed septic implant loosenings: 2 cases with renal transplantation and 1 of alcoholism. Radiolucent lines were found in 9 cases (12.5%), mostly in zones 1 and 2 underneath the TPP. Of these, 1 with an idiopathic osteonecrosis was assessed to be radiologically loosened. The overall failure rate was 9.7%, with a proportion of 36.4% in patients with renal transplantation. Excluding this specific patient group, the failure rate was 4.9%. CONCLUSIONS: Femoral head necrosis following renal transplantation and extension of the necrotic area into the femoral neck are contraindications for TPP. Excluding these patients, the TPP shows comparable mid-term results to cementless stemmed prostheses and supplies advantages especially for younger patients, because of its metaphyseal, bone-preserving fixation. However, evaluation of the clinical impact of the TPP in comparison with other cementless femoral stem systems requires long-term examinations in the future.

Adult↗
PubMed2002

Dislocation of the polyethylene liner in hip arthroplasty: 6 patients with dislocation within 3 years.

We revised 6 patients with early destruction of the liner in a cementless press-fit acetabular cup. They had no signs of infection or evidence of trauma. The failures were probably due to rotation of the liner inside the metal shell and destruction of the polyethylene by the cutting edge of the metal. This early complication may be difficult to diagnose because of normal radiographs. We suggest that the manufacturer should provide the insert with a metal marker to make this complication easier to detect.

Adult↗
PubMed2002

Effect of methylprednisolone on reperfusion after femoral head ischemia.

An episode of ischemia and reperfusion of the femoral head is thought to be the common pathway in the pathogenesis of femoral head necrosis. The influence of short-term high-dose steroid treatment on femoral head reperfusion after ischemia was investigated in a porcine model. Twenty-two pigs were randomized to receive methylprednisolone 20 mg/day/kg bodyweight intramuscularly for 3 days followed by methylprednisolone 10 mg/day/kg bodyweight for 11 days (n = 11), whereas the control group (n = 11) received no treatment. Femoral head ischemia was achieved by 6 hours of unilateral intraarticular hip pressure increase to 250 mm Hg. Femoral head blood flow was estimated using radiolabeled microspheres (15 microm in diameter) before ischemia, during hip tamponade, and 4 hours after tamponade release. Femoral head blood flow was lower in the corticosteroid treated pigs. Subtotal femoral head ischemia was documented in both groups during joint tamponade. Apart from two femoral head epiphyses in either group, reperfusion after tamponade release on the average occurred to a blood flow level similar to that before ischemia. Short-term high-dose methylprednisolone treatment depressed bone perfusion in general, but had no effect on reperfusion after femoral head ischemia in the porcine model.

Animals↗
PubMedDate not supplied

Results of elbow endoprostheses in patients with rheumatoid arthritis in correlation with previous operations.

Fifty-nine patients with rheumatic destruction of the elbow received 20 St Georg, 20 GSB III, 13 Souter-Strathclyde, and 13 Kudo endoprostheses. Among the various prosthetic categories, 43.9% of the joints had had preceding rheumatoid surgery (a previous synovectomy had been performed in 10 joints at a mean of 4.1 +/- 3.7 years and a resection interposition arthroplasty had been performed in 19 cases 4.2 +/- 1.8 years before endoprosthetic replacement). We examined 51 patients with 54 prostheses after a mean follow-up of 5.7 +/- 4.1 years using the Inglis score and analyzing all radiographs. Complications occurred in 20% of the St Georg prostheses, 25% of the GSB III prostheses, and 23% of the Souter-Strathclyde prostheses. Of the St Georg prostheses, 6 (30%) had to be exchanged, as well as 4 (20%) of the GSB III prostheses and 4 (30.7%) of the Souter-Strathclyde prostheses. Of the primarily implanted joints, the St Georg prostheses measured 77.7 +/- 7.7 on the Inglis score, GSB III 89.6 +/- 7.2, Souter-Strathclyde 88.4 +/- 6.5, and Kudo 89.7 +/- 4.4. Radiolucent lines greater than 1 mm were observed in 26% of the St Georg prostheses, 23% of the GSB III prostheses, 27% of the Souter-Strathclyde prostheses, and 9% of the Kudo prostheses. In contrast to the clinical results, the intraoperative and postoperative complications, as well as the rate of failure and radiolucent lines, showed a statistically significant relationship to previous operations of the joints, especially with the resection interposition arthroplasty. We conclude that resection interposition arthroplasty seems to be associated with complications and failures when a subsequent endoprosthesis is used.

Aged↗