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Biomedical subjects

M Porsch

Publications and source records attributed to M Porsch.

At least 19 recordsLinked to original sources
PubMed2003

Histological findings of the femoral bone after cement removal in hip revision. An experimental study of cadaver femurs with two different cement removal procedures.

Cement removal in hip revision arthroplasty is often a time-consuming procedure, lengthy and tedious. Intraoperative bone damage is one of the more common complications. In the present study, the conventional cement removal method is compared with a new method by means of a histological study concerning potential negative effects to cortical or spongious bone. Histological studies on human cadaver femurs demonstrate no deleterious effects on the endosteal bone when cement was removed with this new device. The ballistically driven chiselling system (OrthoClast) is safe to the bone stock and shows no increased risk of bone damage over the conventional technique with mallet and chisel.

Arthroplasty, Replacement, Hip↗
PubMed2002

Removal of well-fixed or porous-coated cementless stems in total hip revision arthroplasty.

The removal of well-fixed or porous-coated cementless stems is demanding and associated with a hig perioperative risk to the patient. Only a few surgical techniques have been published about this procedure. We introduce a special, ballistically driven, flexible chisel for the disruption of bone ingrowth or fibrous encapsulation. In six cases the stem removal was successful after 8-15 min (average 12,2 min) without damage to the bone. Reimplantation is possible with standard stems for primary surgery. This surgical technique leads to a predictable procedure, reduces the risk for the patient, the operation time and costs. We are continuing with this technique under supervision by the local Ethics Commission.

Aged↗
PubMed2002

Two-stage exchange of infected knee arthroplasty with an prosthesis-like interim cement spacer.

Two-stage revision in infected knee arthroplasty is standard practice. One problem during the interim period is soft tissue fibrosis. Attempts have been made to preserve leg length and ligament length by introducing spacers, usually made out of antibiotic-loaded bone cement. We present a new interim prosthesis, which is made intra-operatively out of polymethylmethacrylate (PMMA). Antibiotic-loaded cement provides a therapeutic level of antibiotics in the periarticular soft tissue. We report the results in ten patients, who were treated with this prosthesis-like spacer and were prospectively studied. After an average follow-up of 13.5 months, there was no recurrent infection.

Aged↗
PubMed2001

Cement removal with an endoscopically controlled ballistically driven chiselling system. A new device for cement removal and preliminary clinical results.

In this paper, we introduce a newly developed miniaturised chiselling system (Swiss OrthoClast) which allows endoscopically controlled cement removal even from deep within the femur in hip revision arthroplasty. The intraoperative handling is demonstrated and illustrated. The device consists of a control unit, a handpiece, a set of chisels of different lengths, shape, and tip geometry, a set of plug extraction tools, and a special intrafemoral endoscope. It uses simple ballistic principles to effect fracturing of the bone cement. Inside the handpiece the projectile is accelerated and strikes the chisel head. The tip moves at high speed and with a small excursion towards the cement, which is fragmented mechanically by the movement of the chisel tip without generating heat. The device is being validated in a prospective, international, multicenter study, and we include here the results of the first 28 clinical procedures of cement removal. The duration of the procedure varied from 13 to 75 min, with an average of 32 min. In all but one case, the cement was completely removed. We noted one case of cortical fissuring.

Aged↗
PubMed2000

Saphenous neuralgia after arthroscopically assisted anterior cruciate ligament reconstruction with a semitendinosus and gracilis tendon graft.

A case report of saphenous neuralgia following arthroscopically assisted anterior cruciate ligament reconstruction with hamstring tendons is presented. The patient complained of paresthesia in the anteromedial region of the lower leg and tenderness at the medial side of the knee without motor or reflex abnormalities. Because saphenous neuralgia can mimic disorders of the knee, peripheral vascular disease, and lumbar nerve root compression, diagnosis can be confirmed by anesthetic blockade. The patient underwent saphenous neurolysis. Six months after surgery, the patient had normal cutaneous sensation at the medial aspect of the lower leg and ankle and she no longer complained of any painful dysesthesia. To minimize the risk of damaging the saphenous nerve when harvesting hamstring tendons, the knee should be flexed and the hip external rotated.

Adult↗
PubMed2000

Defective pigment granule biogenesis and aberrant behavior caused by mutations in the Drosophila AP-3beta adaptin gene ruby.

Lysosomal protein trafficking is a fundamental process conserved from yeast to humans. This conservation extends to lysosome-like organelles such as mammalian melanosomes and insect eye pigment granules. Recently, eye and coat color mutations in mouse (mocha and pearl) and Drosophila (garnet and carmine) were shown to affect subunits of the heterotetrameric adaptor protein complex AP-3 involved in vesicle trafficking. Here we demonstrate that the Drosophila eye color mutant ruby is defective in the AP-3beta subunit gene. ruby expression was found in retinal pigment and photoreceptor cells and in the developing central nervous system. ruby mutations lead to a decreased number and altered size of pigment granules in various cell types in and adjacent to the retina. Humans with lesions in the related AP-3betaA gene suffer from Hermansky-Pudlak syndrome, which is caused by defects in a number of lysosome-related organelles. Hermansky-Pudlak patients have a reduced skin pigmentation and suffer from internal bleeding, pulmonary fibrosis, and visual system malfunction. The Drosophila AP-3beta adaptin also appears to be involved in processes other than eye pigment granule biogenesis because all ruby allele combinations tested exhibited defective behavior in a visual fixation paradigm.

Adaptor Protein Complex alpha Subunits↗
PubMed1999

[Insurance expert assessment of traumatic Achilles tendon rupture. A case report].

Achilles tendon ruptures are among of the most frequent tendon ruptures. Usually middle aged men with infrequent sports activity are involved. In most cases histopathology reveals degenerative changes within the tendon. Unusual rupture location and physical signs of trauma should lead one to consider a traumatic origin of the rupture. Traumatic origin can be confirmed by the accident history and physical signs as well as with the histopathology of the rupture site and possibly a tissue section far away the rupture site. This information can be helpful in insurance inquiries.

Achilles Tendon↗
PubMed1999

Metacarpophalangeal joint arthroplasty in rheumatoid arthritis: results of Swanson implants and digital joint operative arthroplasty.

We discuss 69 metacarpophalangeal (MP) implant arthroplasties performed in 30 patients with rheumatoid arthritis. The follow-up averaged 5 years. We studied 19 finger joint prostheses by Condamine, digital joint operative arthroplasty (stabilized version; DJOA) and 50 flexible silicone Swanson implants. We used a new comprehensive scoring system to evaluate the MP alloarthroplasties. Such a scoring system incorporates clinical and radiological data. The outcome following MP joint replacement with DJOA was never evaluated as 'good'; in 11 joints the result was 'fair', and in 8 joints, 'poor'. As regards MP arthroplasty with Swanson implants, the results were evaluated as 'good' in 40 joints, as 'fair' in 10 joints, and in none as 'poor'. In our series, DJOA did not provide stability in arthritic MP joints. In all joints replaced with DJOA, dislocation of the articulating surfaces and signs of loosening were present. We regard three factors as being the main causes contributing to the poor outcome of DJOA when used as MP replacements. Firstly, the proximal prosthetic component is poorly matched to the anatomical shape of the metacarpal bone (conisation of the bone). Secondly, adequate coaptation cannot be achieved with this prosthetic design, even in the presence of extensive soft-tissue reconstruction. Thirdly, the use of polyethylene in MP joint replacements is questionable. In contrast, the silicone Swanson implants in our series provided superior results when used as MP implants in the rheumatoid hand.

Adult↗
PubMed1999

Functional results after partial pelvic resection in Ewing's sarcoma of the ilium.

Ewing's sarcoma of the pelvis has an unfavourable prognosis. The clinical and functional results of 7 patients who had a Ewing's sarcoma of the pelvis stage IIB were reviewed. All patients received multiple-agent chemotherapy pre- and postoperatively (modified T6 and T2 protocol according to Rosen) and underwent local resection of the pelvic tumour. According to Enneking, five patients had a type IA resection, one patient type I and another type IIA. One patient received a course of radiation therapy postoperatively (50 Gy). Six of seven patients showed a good regression of the tumour after preoperative chemotherapy. One patient who had a giant-cell Ewing's sarcoma died of local recurrence and lung metastases 29 months postoperatively. The remaining six patients were monitored radiographically and clinically according to Enneking's functional evaluation score after a follow-up period of 136 months (range 40-199 months). All were free of disease and had neither local recurrence nor metastases. In five patients the functional results were rated as "good" or "excellent". The good results depend mainly on the reconstruction of the pelvic girdle and its mechanical stability.

Adolescent↗
PubMed1999

[Possibilities of avoiding an intra-femoral increase in pressure during hip revision surgery].

An earlier experimental study carried out by us revealed an increase in intrafemoral pressure during removal of cement in hip revision arthroplasty. This increase is greater while removing cement from the distal femoral shaft. Maximum pressure increases occurred while removing the medullary plug (cement stopper), and the measured pressure of more than 150 mmHg is associated with an increased risk of fat embolism. The present study shows that this phenomenon can be avoided through the use of cannulated instruments.

Femur↗
PubMed1998

Isolation of a Drosophila T-box gene closely related to human TBX1.

T-box genes, in all metazoans studied from nematode to man, exist in small gene families. They encode transcription factors with a novel, large, and highly conserved DNA binding domain termed the T-domain. In all cases studied, T-box genes have important developmental roles. Two familial diseases, Holt-Oram syndrome and ulnar-mammary syndrome, were recently shown to be caused by mutations in the human T-box genes TBX5 and TBX3, respectively. T-box genes were first identified in Drosophila and mouse. Two of the three known Drosophila T-box genes show a close sequence homology to mammalian genes. Similarities in the phenotypes of fly and mammalian mutants can be taken as evidence of functional conservation. We report here the isolation of a fourth Drosophila T-box gene, optomotor-blind-related gene-1 (org-1), closely related to mouse and human TBX1. We localized TBX1 to chromosomal band 22q11, confirming a recent report, and discuss TBX1 as a candidate gene for DiGeorge and related syndromes.

Amino Acid Sequence↗
PubMed1998

[Intrafemoral pressure measurement in different cement removal procedures during hip prosthesis replacement operations--experimental study with cadaver femora].

During primary hip arthroplasty an increase in intramedullary pressure (IMP) of up to 1000 mm Hg can be observed. As a result of this increased intrafemoral pressure, intramedullary constituents can pass into the venous circulation creating a risk of fat embolism syndrome (FES). In the present experimental study on 9 femora obtained from human corpses, we investigated the question as to whether various methods of cement removal during total hip revision arthroplasty are also associated with increased intramedullary pressure and a risk of FES. The IMP was recorded with a standardized experimental set-up during removal of cement from the proximal and distal regions, including removal of the cement "tip" and the intramedullary plug. The methods employed for this purpose included the osteotome and mallet, a compressed air powered chisel, and a modified intracorporal lithotripter. All the methods induced fluctuations in the IMP the highest values being recorded for the conventional method using the osteotome and mallet (45 mm Hg) and the lowest values for the intracorporeal lithotripter (7.5 mm Hg). Working on the distal cement caused higher fluctuations in comparison with the proximal region. The study failed to reveal any increase in mean IMP, and all measured values were in the low pressure range (considerably below 150 mm Hg). While there seems to be no apparent risk of an FES developing during removal of cement, careless manipulation of the distal cement plug may result in higher intrafemoral pressures--above 150 mm Hg--thus increasing the risk of a fat embolism syndrome.

Bone Cements↗
PubMedDate not supplied

[Costal osteoid osteoma].

We report about a rare case of osteoid osteoma of the 9th rib in a 32 year old woman. A search of medical literature yielded only 16 reports about costal osteoid osteoma. This tumor should be considered in cases of painful rib without anamnestic trauma.

Adult↗
PubMedDate not supplied

[Total femur replacement following multiple periprosthetic fractures between ipsilateral hip and knee replacement in chronic rheumatoid arthritis. Case report of 2 patients].

Periprosthetic femur fractures are one of the most severe complications in hip surgery. Osteoporosis as seen in patients with rheumatoid arthritis could favour such fractures, which are located mostly between the stems of the hip and knee prostheses. A traumatic event is not even required. The fracture rate increases with predisposing factors, such as preliminary changes of the prosthesis or osteoporosis. This paper reports two patients with rheumatoid arthritis (males, 54 and 71 years old) with femur fractures after total hip and knee replacements. Both had a severe osteoporosis caused by a long-term steroid therapy. Consecutively, both patients showed refractures of the femur with loosening of the osteosynthetic material, so that a total femur replacement was required. However, both patients are able to walk. To reduce the risk of femur fractures between the tips of knee and hip prostheses it is advisable to use knee prostheses without a proximal intramedullary stem. In this way pressure stress is reduced.

Aged↗
PubMedDate not supplied

[Modified intracorporeal lithotripsy for cement removal in hip prosthesis exchange operations--experimental principles].

INTRODUCTION: Particularly problematic in total hip revision arthroplasty is the cement removal out of the depth of the femoral canal; it is also costly in time and effort. The extracorporal shock wave lithotripsy proved to be an unsuitable method. With the present paper we proved experimentally a newly developed endoscopically controlled modified intracorporal lithotripter (Swiss Orthoclast) for the removal of bone cement. METHODS: We tested the efficiency on standardized cement specimens of different manufacturers in vitro. We compared both conventional removing techniques with mallet and chisel and a pneumatically powered chisel with formalin fixed human femora. During these experiments we measured the intrafemoral pressure distally to the cement layer. RESULTS: We achieved a high energy (max. 450 mJ) and a very effective fragmentation of the cement (40 mg fragments calculated on the single impulse of 350 mJ). The endoscopic control ensures a safe control of the cement removal even in the depth of the femoral canal. No bone damage occurred macroscopically and radiologically. No heat or toxic products developed. Using the Swiss Orthoclast the intrafemoral pressure was the lowest possible (7 mbar). Even with hammer and chisel or the pneumatically powered chisel the pressure was too low (max. 55 mbar with mallet and chisel) to cause a fat embolic syndrome. CONCLUSION: As a result of these experiments we started with clinical trials (with permission of the Ethic commission) to evaluate the practicability of the modified intracorporal lithotripter (Swiss Orthoclast) for cement removal.

Arthroscopes↗
PubMedDate not supplied

[Artificial hip replacement in young patients with hip dysplasia--long-term outcome after 10 years].

PURPOSE: The experience gained in three decades of hip arthroplasty includes observations on patients with congenital dysplasia of the hip (CDH) under 20 years of age. A study dealing with hip arthroplasty in patients with osteoarthritis following CDH in such young age is not known in the literature. In the present study we report about a long-term follow-up of 41 total hip arthroplasties which were performed using bone-cement in 29 patients from 1966 to 1995. METHODS: The evaluation of this retrospective study was performed with an questionnaire and a clinical and radiological investigation (Harris hip score, Sutherland activity score). RESULTS: 18 patients with 27 THR (62%) were evaluated clinically and radiologically after a mean duration of follow-up of 10 years and 8 months. Seven additional THR had been revised in the meantime. Kaplan-Meier survival analysis showed a survival rate after 10 years of 64%. Acetabular loosening occurred three times as often as femoral loosening (overall revision rate 41.2%). CONCLUSION: The overall loosening rate of total hip replacement of young patients is significantly elevated. These findings suggest that total hip replacement in young patients with dysplastic hips should be considered most carefully. Implantation of a hip prosthesis is only justified in special cases where alternative procedures are contra-indicated or unacceptable.

Adolescent↗