Biomedical subjects

W Petersen

Publications and source records attributed to W Petersen.

At least 37 records · Page 2Linked to original sources

PubMed2002

[Mechanisms and prevention of kitesurfing injuries].

Aim of this study was to analyse the mechanisms of kitesurfing injuries. For this purpose we performed a survey among 72 kitesurfers in the north of Germany. 31 accidents have been registrated among all 72 athletes during the 2001 season. 3 additional accidents occurred where a windsurfer got injured. 5 athletes had medium injuries such as fractures, all remaining athletes presented with minor injuries, that did not require medical treatment. The incidence of medium kite injuries was 1/1000 hours; the incidence of minor kite injuries was 5/1000 hours. The most common injury mechanism was a direct trauma against things such as stones and boats lying on the beach. The most common situation in which the injury occurred was the lost of control about the kite on the beach or close to the beach due to technical mistakes of the surfer, oversized kites, or the wind conditions (onshore wind, overpower). Further injuries occurred due to collisions with windsurfers or sailing boats. Kitesurfing is a new rapidly growing sport. To date the risk potential of this new sport is unclear. The analysis of the injury mechanisms allows conclusion regarding the prevention of kitesurfing injuries.

Accident Prevention↗

PubMed2002

[Prevention of lower extremity injuries in handball: initial results of the handball injuries prevention programme].

INTRODUCTION: Injuries of the lower extremity lead to disability to perform sports and may cause degenerative changes of the joints. Hence, we developed a specific injury prevention programme for European team handball and tested this programme in a prospective study. METHOD: One handball team (2 nd division) performed a proprioceptive and neuromuscular training during the preseason. The programme consists of 3 different components: 1. Information on injury mechanisms, 2. Proprioceptive training, and 3. Jump training. During the season the exercises have been continued with lower intensity. Another handball team which performed no injury prevention training served as control. Injuries were recorded in a prospective manner. In a retrospective arm of the study we compared the frequency of severe injuries of the training season with the frequency of severe injuries during the last season. RESULTS: In comparison to the last year no player from the prevention training team suffered a severe injury of the ankle or the knee. During the last season three athletes ruptured their anterior cruciate ligament. In the untrained control group one athlete suffered from an ACL rupture and one athlete had a rupture of the lateral ankle ligaments. These findings have no statistical significance because of the low number of individuals investigated. However, the incidence of light and medium injuries was significantly lower in the injury prevention group. CONCLUSIONS: This study demonstrates that proprioceptive and neuromuscular training is appropriate for the prevention of lower extremity injuries. Prevention strategies should be included in routine handball training programmes.

Adult↗

PubMed2002

The blood supply of the posterior tibial tendon.

We studied the vascular pattern of human posterior tibial tendons by injection techniques and immunohistochemically using antibodies against laminin. The intravascular volume of the posterior tibial tendon was determined using a new method of injection of a solution of 99mTc and gelatin ink into the lower legs of cadavers. Three segments of 1 cm length from different regions of the human posterior tibial tendon were measured using a gamma well counter. The main blood supply arises from the posterior tibial artery. Blood vessels enter the paratenon of the posterior tibial tendon via a mesotenon from the posterior aspect. From the paratenon, the blood vessels penetrate the posterior tibial tendon and anastomose with a longitudinally orientated intratendinous network. The number of vessels in the substance of the tendon is consistently less than that in the surrounding paratenon. The distribution of blood vessels within the posterior tibial tendon is not homogeneous. In the retromalleolar region the intravascular volume was significantly reduced with a mean value of 15 microl/g of tendon tissue. There was no significant difference between the mean intravascular volumes of the proximal and distal areas (distal, 27.7 microl/g tendon tissue; proximal, 30 microl/g tendon tissue). The immunohistochemical investigation showed that there was no immunostaining for laminin in the anterior part of the tendon in the region where it passes behind the medial malleolus. This region is avascular. The most frequent site of rupture of the posterior tibial tendon is in the region behind the medial malleolus. A potential endogenous risk factor may be the limited healing potential of avascular tissue.

Aged↗

PubMed2001

The splice variants VEGF121 and VEGF189 of the angiogenic peptide vascular endothelial growth factor are expressed in osteoarthritic cartilage.

OBJECTIVE: Vascular endothelial growth factor (VEGF) has recently been shown to play an important role during endochondral bone formation in hypertrophic cartilage remodeling, ossification, and angiogenesis, but it is not expressed in normal adult cartilage. Since genes expressed during development often reappear in the disease state, we investigated whether VEGF and its receptors (VEGFRs) are expressed in osteoarthritic (OA) cartilage. METHODS: VEGF production in OA cartilage from the tibial plateau was measured by enzyme-linked immunosorbent assay. Deposition of VEGF and VEGFR was determined by immunohistochemistry. Expression of messenger RNA for the different VEGF splice forms and for VEGFR was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: Increased VEGF concentrations were measured in OA cartilage from the tibial plateau, while VEGF was almost undetectable in normal cartilage but could be immunostained within the intracellular and pericellular matrices of OA chondrocytes. In analyses of cartilage samples from all 10 OA patients evaluated, VEGF121 and VEGF189 were identified as the only VEGF splice forms expressed. RT-PCR and immunohistochemistry for VEGF in normal hyaline cartilage yielded negative findings. In addition to VEGF, VEGFR-2 (kinase domain region/fetal liver kinase 1), but not VEGFR-1 (fms-like tyrosine kinase 1), could be detected by RT-PCR in OA cartilage and immunostained on OA chondrocytes. CONCLUSION: Apart from its production in hypertrophic chondrocytes, VEGF is also produced in chondrocytes of OA cartilage. While the splice variant VEGF189 binds to extracellular matrix proteoglycans, VEGF121 is diffused freely. Both proteins should contribute to the inflammatory process by autocrine/paracrine stimulation of chondrocytes, chemotaxis of macrophages, and promotion of angiogenesis.

Alternative Splicing↗

PubMed2001

Tailor's bunion: results of a scarf osteotomy for the correction of an increased intermetatarsal IV/V angle. A report on ten cases with a 1-year follow-up.

INTRODUCTION: The aim of this study was to analyze clinical and radiological results of scarf osteotomy for the correction of an increased intermetatarsal IV/V angle in patients with symptomatic tailors bunion. PATIENTS AND METHODS: Between 1997 and 1998, we performed a scarf osteotomy for the correction of an increased intermetatarsal IV/V angle (IMA) in ten cases. The indication was a painful prominence of the fifth metatatarsal with an increased IMA. Fixation of the osteotomy was performed with two 1.7-mm titanium miniscrews. Mobilization was allowed with full weight-bearing, with a forefoot relief orthosis. Clinical results were evaluated with the forefoot scoring system (ffss). The determination of the IMA was performed with weight-bearing dorsoplantar radiographs. RESULTS: All osteotomies healed within the first 6 postoperative weeks. Removal of the screws was not necessary in any case. The mean preoperative ffss was 29.5 points. At the last follow-up, the mean value of the ffss was 73 points and no patient presented a painful prominence above the fifth metatarsal head. The mean IMA was reduced significantly from 10.3 to 6.8 degrees. DISCUSSION: The scarf osteotomy is an adequate surgical procedure for the correction of an increased IMA in patients with symptomatic tailor's bunion.

Adult↗

PubMed2001

Autologous osteochondral transplantation using the diamond bone-cutting system (DBCS): 6-12 years' follow-up of 35 patients with osteochondral defects at the knee joint.

Thirty-five patients with severe osteochondral defects were treated by autologous osteochondral transplantation between 1986 and 1992. The majority of patients (27) suffered from osteochondrosis dissecans, while 8 patients presented with posttraumatic osteochondral defects. The grafts were harvested with a diamond bone cutter from the posterior part of the medial or lateral femoral condyle. In 29 patients the lesion was located at the lateral part of the medial femoral condyle, in 3 it was at the lateral femoral condyle, and in 3 at the patella. Twenty-nine patients could be examined at the follow-up between 6 and 12 years later (mean follow up 8.1 years). Using the standard cartilage evaluation form, the transplanted knees of 12 patients were graded as normal (grade I), 14 knees were nearly normal (grade II), while 3 patients presented with an abnormal result (grade III). All 3 of them had a varus malalignment and refused a high tibial correction osteotomy against our advice. No patient was assessed as severely abnormal (grade IV). The majority of patients improved their activity level and the functional status of the joint. Twelve patients developed new radiological signs of osteoarthrosis with a decrease in the radiological score of Kellgren and Lawrence by about one stage. We conclude that autologous osteochondral transplantation with the diamond bone-cutting system is an effective method in the treatment of severe osteochondral defects.

Adult↗

PubMed2001

Immunolocalization of the angiogenetic factor pleiotrophin (PTN) in the growth plate of mice.

The aim of this study was to find out whether and where the angiogenic agent pleiotrophin (PTN) occurs within the growth plate. We investigated paraffin-embedded tissue sections of ten male mice with an antibody directed against the recombinant PTN. Immunostaining for PTN was positive within the cytoplasm and the pericellular matrix of osteoblasts which lined the longitudinal mineralized septae of the epiphyseal plate. Within the zone of hypertrophic chondrocytes, immunolabelling for PTN was positive in the pericellular matrix of hypertrophic chondrocytes and within the opened lacunae of the apoptotic hypertrophic chondrocytes. The resting zone and the proliferation zone were PTN negative. The results of our study suggest that the known angiogenetic peptide PTN plays a role in the process of angiogenesis in the growth plate.

Animals↗

PubMed2001

The angiogenic peptide vascular endothelial growth factor is expressed in foetal and ruptured tendons.

The Achilles tendon is one of the most common sites of injury and rupture. Evidence suggests that local vascularisation is involved in this aetiology. We investigated the expression of one important angiogenic factor, the vascular endothelial growth factor (VEGF), in normal and pathologic human Achilles tendons using immunohistochemical, biochemical, molecular and cell biology methods. VEGF could be immunostained in tenocytes of ruptured and foetal Achilles tendons, but not in normal adult ones. In microvessels, the VEGF receptor VEGFR-1 (flt-1) could be visualised as well. High VEGF levels were measured in homogenates from ruptured adult, lower ones in foetal and negligible concentrations in normal adult Achilles tendons using enzyme-linked immunoassay (ELISA) and Western blot experiments. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that the splice variants VEGF121 and VEGF165 are exclusively expressed. In tenocytes cultivated from newborn rat Achilles tendons, hypoxia or epidermal growth factor (EGF) raised VEGF production moderately whereas their combination resulted in a strong, synergistic induction. These results prove the presence of an angiogenic peptide and vascularisation in ruptured and foetal tendons and support the view that microtrauma or degeneration in the Achilles tendon precedes its rupture.

Achilles Tendon↗

PubMed2001

Expression of natural peptide antibiotics in human articular cartilage and synovial membrane.

In view of frequent present use of invasive procedures on limb joints, it is astonishing that articular joint inflammation is a rare event. We questioned whether antimicrobial peptides play a role in protecting human articular cartilage and synovial membrane against inflammatory agents. Our results implicate defensins in the protection of human articular joints against pathogens.

Anti-Bacterial Agents↗

PubMed2001

Collagenous fibril texture of the gliding zone of the human tibialis posterior tendon.

UNLABELLED: Light microscopy and scanning electron microscopy was used to describe the collagenous fibril texture of the wrap around region of the human tibialis posterior tendon in human cadavers. In the region where the tendon wraps around the medial malleolus, the anterior part of the tendon directed towards the pulley had the structure of fibrocartilage. This zone started approximately 25-30 millimeters from the navicular insertion. Scanning electron microscopy of the collagen fibril texture revealed three different layers in the fibrocartilaginous zone. The anterior surface was covered by a meshwork of thin unbanded fibrils with a diameter of app. 30 nm. Beneath the superficial network there was an app. 150 microm thick layer of banded collagen fibrils, These fibrils formed lamella-like bundles which intersected at various angles. The main portion of the collagen fibrils lie below this layer and run in a longitudinal direction. The longitudinal fibrils were divided into bundles by loose connective tissue. The location of the fibrocartilage corresponds to the region where the tibialis posterior tendon wraps around the medial malleolus which serves as a pulley. CLINICAL SIGNIFICANCE: Our study documented the existence of a fibrocartilaginous zone with a specific collagen fibril texture that corresponds to a possible site of rupture, as reported by several authors. Due to special collagen fibril texture the fibrocartilage may be more vulnerable to repetitive tensile micro-trauma.

Adult↗

PubMed2001

Splice variants VEGF121 and VEGF165 of the angiogenic peptide vascular endothelial cell growth factor are expressed in the synovial tissue of patients with rheumatoid arthritis.

OBJECTIVE: To determine the expression of the angiogenic peptide vascular endothelial growth factor (VEGF, also known as vascular permeability factor, VPF) in the synovium of patients with rheumatoid arthritis (RA). METHODS: Expression of VEGF protein from the synovial tissue of 10 patients with RA was monitored by ELISA and visualized by immunocytochemistry, and by double-staining with the VEGFR-1/flt-1. VEGF mRNA and its splice variants were determined by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: VEGF protein was strongly increased in rheumatoid synovium and localized at the synovial surface, whereas the VEGF receptor flt-1 (VEGFR-1) was visualized on microvessels in close vicinity. In synovial tissues from all 10 patients with RA, VEGF121 and VEGF165 were identified at the mRNA level as the only VEGF splice forms expressed. CONCLUSION: Since VEGF165 and VEGF121 are differently diffusible due to their opposite heparan sulfate-binding properties, they act at different distances. The presence of VEGF121 may explain induction of the VEGFR-1 on infiltrating blood vessels near the synovial surface.

Alternative Splicing↗

PubMed2000

Insertion of autologous tendon grafts to the bone: a histological and immunohistochemical study of hamstring and patellar tendon grafts.

This study examined the structure of the insertion of autologous tendon grafts used for anterior cruciate ligament reconstruction. Biopsy specimens of the femoral paragraph signand tibial bone graft interface were obtained at revision surgery in 14 patients (6 with hamstring grafts, 8 with a patella tendon graft). The specimens were analyzed by light microscopy and immunohistochemistry (confirming type I, type II, and type III collagen). The insertions of hamstring autografts to the bone tunnel have three characteristic histological zones. Zone 1 is composed of the dense connective tissue of the graft. The collagen fibers of the graft enter the bone under oblique angles. Zone 2 is composed of woven bone with a sharp transition to the lamellar bone of the tibia (zone 3). Immunohistochemistry revealed the presence of type I and type III collagen within the dense connective tissue of the graft. The woven and lamellar bone showed positive immunostaining for antibodies against type I collagen only. This structure resembled a fibrous ligament or tendon insertion. In the majority of patients with a patella tendon graft the structure of the insertion resembled a chondral enthesis. The chondral insertion of the graft to the bone is composed of four characteristic zones. Between the dense connective tissue of the graft (zone 1) and bone (zone 4) there is a zone of fibrocartilage (zone 2). Close to the bone the fibrocartilage is mineralized (zone 3). Within the fibrocartilage the immunohistochemical analysis confirmed type II collagen. This structure resembled the chondral enthesis of the normal anterior cruciate ligament. However, in cases in which the distal bone bloc has been fixated outside the tibial tunnel, the tibial insertion of the patellar tendon graft resembled a fibrous insertion. While both types of tendon grafts heal to the bone of femur and tibia, the insertion of patella tendon grafts healing by bone plug incorporation resembles the chondral insertion of the normal anterior cruciate ligament and may have a more physiological connection to the bone than hamstring grafts.

Humans↗

PubMed2000

Structure of the human tibialis anterior tendon.

The structure and vascular pattern of the human tibialis anterior tendon was investigated using injection techniques, light and transmission electron microscopy and immunohistochemistry. From the well vascularised peritenon, blood vessels penetrate the tendon tissue and anastomose with a longitudinally oriented intratendinous network. The distribution of blood vessels within the tibialis anterior tendon was not homogenous. The posterior part of the tendon had a complete vascular network that extends from the musculotendinous junction to the insertion at the first metatarsal and medial cuneiform bones. In the anterior half, the tissue was avascular in a zone with a length of 45-67 mm. This zone was covered by a single layer (approximately 30 microm) of oval shaped cells. Transmission electron microscopy showed that these cells have the characteristics of chondroid cells. This region was stained by Alcian blue at pH 1 which indicates a high concentration of acid glycosaminoglycans and immunohistochemical staining for chondroitin-4-sulphate, chondroitin-6-sulphate and aggrecan was positive. However, immunostaining for the typical cartilage specific type II collagen within this zone was negative. The location of the avascular zone corresponds to the region where the tibialis anterior tendon wraps around the superior and inferior retinacula which serve as fibrous pulleys. This is the region where most spontaneous ruptures of the tibialis anterior tendon occur. The presence of fibrocartilage within gliding tendons is a functional adaptation to compressive and shearing forces. In contrast to reports from the literature about the structure of gliding tendons wrapping around a bony pulley, the gliding zone of the tibialis anterior tendon has only a narrow layer of chondroid cells and proof of type II collagen is lacking.

Adult↗

PubMed2000

Blood supply of the peroneal tendons: injection and immunohistochemical studies of cadaver tendons.

We studied the vascular pattern of human peroneal tendons with injection techniques and immunohistochemically by using antibodies against laminin The main blood supply arises from the peroneal artery. The distal part of the peroneus longus tendon is supplied by branches of the medial tarsal artery. Blood vessels enter the peritenon of both tendons via a mesotenon from the posterior aspect. From the peritenon, the blood vessels penetrate the peroneus brevis and peroneus longus tendons and anastomose with a longitudinally-oriented intratendinous network. The amount of vessels in the tendon substance is consistently less than in the surrounding peritenon. The distribution of blood vessels in the peroneal tendons is not homogeneous. In the region where the peroneus brevis tendon passes through the fibular groove, the longitudinally-oriented intratendinous vascular network is interrupted and the tendon is almost avascular. In this region, the tendon is squeezed between the peroneus longus tendon and the bony slide bearing of the lateral malleolus. The peroneus longus tendon has two avascular zones. In the region where the peroneus longus tendon curves around the lateral malleolus and the peroneal trochlea of the calcaneus, the anterior part of the tendon which is directed towards the pulley is avascular. A second avascular zone is located more distally in the region where the tendon changes direction and wraps around the cuboid.

Adult↗

PubMed2000

Quantitative assessment of intravascular volume of the human Achilles tendon.

The pathogenesis of Achilles tendon rupture remains unclear, but vascular patterns may play an important role. We determined the intravascular volume of the Achilles tendon using a new method with injection of radioisotopes. A solution of Tc-99m and gelatin-ink was injected into the lower limbs of body donors. The intravascular volume of each 1 cm section of the Achilles tendon was measured using a gamma well counter. We found that the distal part of the Achilles tendon (0-2 cm above the calcaneus) had an intravascular volume of 59-98 microL/g tendon tissue. In the middle part of the tendon (3-6 cm above the calcaneal insertion), the intravascular volume was much less: 2743 microL/g tissue. The proximal part of the tendon (7-9 cm) had an intravascular volume between 51-100 microL/g tendon tissue. The reduced vascularization in the middle part of the human Achilles tendon may play a role in degeneration and spontaneous rupture of the tendon.

Achilles Tendon↗

PubMed1999

[Blood supply of the quadriceps tendon].

Degenerative changes have been considered to be a cause for spontaneous quadriceps tendon rupture. Aim of this study is to investigate the microvasculature of the quadriceps tendon by injection techniques and immunohistochemical methods (antibodies against laminin) with regard to the pathogenesis of tendon degeneration. The blood supply of the quadriceps tendon arises from descending branches of the lateral circumflex femoral artery, by branches of the descending geniculate artery and by branches of the medial and lateral superior geniculate arteries. Blood vessels penetrate the tendon from the surrounding connective tissue and anastomose with a longitudinally orientated intraligamentous network. Compared to the surrounding synovial layer, the amount of vessels in the tendon substance is greatly reduced. The distribution of blood vessels within the quadriceps tendon is not homogenous. The anterior or superficial part of the tendon has a complete vascular network that extends from the musculo-tendinous junction to the patella. Within the deep portion of the quadriceps tendon there is an oval shaped avascular area which measures app. 30 mm in length and app. 15 mm in width. Within this area the immunohistochemical proof of laminin is negative. An explanation for the absence of blood vessels may be compressive stress caused by the patellar groove which serves as hypomochlion for the quadriceps tendon when the knee is flexed. The occurrence of an avascular zone within the deep layer of the tendon that is directed to the joint cavity may explain the frequency of degenerative changes in this region.

Adult↗

PubMed1999

[Bilateral spontaneous rupture of the quadriceps tendon in a patient with Wilson disease. A case report].

A 58-year old man with Wilson's disease sustained a bilateral spontaneous rupture of the quadriceps tendon. The histological investigation showed advanced degeneration of tendon structure and copper deposits. After tenosuture the patient had complete cure with full range of movement. We discuss about relation of Wilson's disease, copper deposits and degenerative changes of tendon tissue.

Calcium↗

PubMed1999

Blood and lymph supply of the posterior cruciate ligament: a cadaver study.

Injection techniques, immunohistochemical (antibodies against laminin), and histochemical (5'-nucleotidase activity) methods were employed to describe the vascular pattern of the human posterior cruciate ligament (PCL); in parallel we used conventional light microscopy and immunohistochemical techniques to visualize the histological structure of the PCL. The blood supply of the PCL mainly arises from the middle geniculate artery. The ligament is covered by a synovial fold where the terminal branches of the middle geniculate artery form a periligamentous network. From the synovial sheath, the blood vessels penetrate the ligament in a horizontal direction and anastomose with a longitudinally orientated intraligamentous network. Within the ligament the blood vessels are located in the loose connective tissue that is sited between longitudinal fibre bundles. Histologically the longitudinal fibre bundles of the ligament consist of dense connective tissue. Lymphatics accompany most of the smaller blood vessels, showing similar regional distribution. Compared to the surrounding synovial layer, the amount of vessels in the substance of the ligament is lower. The distribution of blood vessels within the PCL is not homogenous: we detected three avascular areas within the ligament. Both fibrocartilaginous entheses of the PCL are devoid of blood vessels, and a third avascular zone is located in the central part of the middle third. The histological structure of this zone varies from the rest of the PCL which consists of the characteristic dense connective tissue. In the central part of the PCL the tissue resembles fibrocartilage: the cell shape is round, the pericellular matrix of those cells is rich in acid glycosaminoglycans and the immunohistochemical demonstration of type II collagen is positive. The occurrence of an avascular zone within the central part of the middle third of the PCL where the tissue consists of fibrocartilage has not been described in the literature.

Aged↗