Search PubMed⌕ Search

Biomedical subjects

A J van der Linden

Publications and source records attributed to A J van der Linden.

At least 19 recordsLinked to original sources
PubMed1998

Quantitative histological analysis of bony ingrowth within the biomaterial Polyactive implanted in different bone locations: an experimental study in rabbits.

The quantity of bone formed in cylinders of a newly developed erodible copolymer, Polyactive (PA60/40) was examined. PA60/40 was implanted in three different bone locations in the rabbit: in the cortex, in bone marrow and in trabecular subchondral bone. Bony ingrowth was assessed after 4, 8, 26 and 52 w after the operation and investigated by histology and image analysis. The ingrowth of bone was observed in PA60/40 placed in the cortex from 4 w onwards. After 8 w, more than 90% of the pores of the biomaterial were filled with dense bone. In bone marrow, initially some bone formation was seen. After 26 w, all newly formed bone was resorbed. Subchondral bone formation was less than in the cortex of the femur, but somewhat comparable to the amount of bone found in healthy trabecular bone. Bone formation appeared not to be affected by the degradation of the biomaterial. It was concluded that Polyactive is a suitable bone graft substitute. Bone formation within PA60/40 is site-dependent and this follows Wolff 's law.

Journal Article↗
PubMed1997

Dystrophic kyphoscoliosis in neurofibromatosis type I: a report of two cases and review of the literature.

We report two cases of dystrophic scoliosis in neurofibromatosis, each of particular interest. In the first, kyphosis was present with vertebral rotatory subluxation but no neurologic impairment, while the second patient showed manifest paraplegia due to rapidly progressive kyphoscoliosis. The importance of early surgical stabilisation, both front and back if possible, is stressed. Very sharp curves with progressive myelopathy should not be treated with halo-femoral traction because of the potential danger of evoking permanent paraplegia.

Adolescent↗
PubMed1997

Long-term results of rib perichondrial grafts for repair of cartilage defects in the human knee.

Eighty-eight patients with articular cartilage defects in the knee were treated by perichondrial arthroplasty between 1986 and 1992. An autogenous strip of costal perichondrium was fixed in place with fibrin glue, followed by immobilisation, continuous passive motion, and partial weightbearing. The results were evaluated using the Hospital for Special Surgery Score for knee function, radiographs, arthroscopy and the patient's subjective opinion. The results after a mean follow-up of 52 months were good in 38%, fair in 8% and poor in 55%. Previous drilling or shaving of a defect, concomitant osteoarthritis, older age and a long history of complaints proved to be contraindications. Good results were seen in 91% of isolated defects. Perichondrial arthroplasty can be beneficial in the repair of cartilage defects. It will reduce symptoms in carefully selected cases, and avoid more extensive operations for osteoarthritis.

Adolescent↗
PubMed1996

Femoral canal occlusion in total hip replacement using a resorbable and flexible cement restrictor.

We have investigated the use of a conically-shaped cement plug made of Polyactive (PA), a biodegradable copolymer. The flexibility and hydrogel properties were thought to facilitate occlusion of the femoral canal even when it was oval or irregular in shape. The function of the plug was first compared with that of the Thackray polyethylene model in 16 artificial plastic femora. The maximum intramedullary pressure achieved during cementing was ten times higher with the biodegradable model. Migration or leakage of cement did not occur when the diameter of the femoral canal was equal to or smaller than the diameter of the plug. We also showed that the biodegradable properties of this implant were such that it did not require removal during revision. The new plug was tested in a pilot clinical trial. At two years only two out of 21 patients had evidence of migration or leakage of cement, probably due to a mismatch in the size of plug and femoral canal. There were no local changes in the femur.

Biocompatible Materials↗
PubMed1996

Local corticosteroid injection versus Cyriax-type physiotherapy for tennis elbow.

We performed a prospective, randomised trial on 106 patients to compare the effects of local corticosteroid injections with physiotherapy as advocated by Cyriax in the treatment of tennis elbow. The main outcome measures were the severity of pain, pain provoked by resisted dorsiflexion of the wrist, and patient satisfaction. At six weeks 22 of 53 patients in the injection group were free from pain compared with only three in the physiotherapy group. In the corticosteroid-treated group 26 patients had no pain on resisted dorsiflexion of the wrist compared with only three in the physiotherapy group. Thirty-five patients who had injections and 14 who had physiotherapy were satisfied with the outcome of treatment at six weeks. At the final assessment there were 18 excellent and 18 good results in the corticosteroid group and one excellent and 12 good results in the physiotherapy group. There was a significant increase in grip strength in both groups but those with injections had a significantly better result. After one year there were no significant differences between the two groups. Half of the patients, however, had received only the initial treatment, 20% had had combined therapy and 30% had had surgery. We conclude that at six weeks, treatment with corticosteroid injections was more effective than Cyriax physiotherapy and we recommend it because of its rapid action, reduction of pain and absence of side-effects.

Adult↗
PubMed1994

Prevalence of blindness and low vision of people over 30 years in the Wenchi district, Ghana, in relation to eye care programmes.

A population based survey on the prevalence of major blinding disorders was conducted in the Wenchi district in central Ghana between March and May 1991. In 10 villages, 1425 people of 30 years and older were screened, using the WHO eye examination record. The prevalence of bilateral blindness above 30 years proved to be 1.7% (best acuity < 3/60): the prevalence of low vision above 30 years was 2.0% (best visual acuity 6/18 to 3/60). The causes of blindness were determined as cataract (62.5%), onchocerciasis (12.5%), corneal opacity (non-trachomatous) (8.2%), refraction anomalies (4.2%), phthisis bulbi (4.2%), optic atrophy (4.2%), and vascular retinopathy (4.2%). In the Wenchi district, 1.0% of the population over the age of 30 years was found to need a cataract extraction because of blindness of both eyes. Another potential 1.0% needs a cataract extraction because of low vision. A minor second study (n = 149) was undertaken in the same district, but in a village in an area near the Black Volta river in which onchocerciasis is endemic. The prevalence of blindness (8.1%) and low vision (3.4%) caused by onchocerciasis and cataract both proved to be higher. The survey provided the basis for a preventive and curative eye care programme.

Adult↗
PubMed1994

The effect in vitro of irrigating solutions on intact rat articular cartilage.

Rat patellae were preincubated with culture medium M199 for one hour and then with either fresh culture medium or Ringer's solution, Ringer lactate, Ringer glucose, normal saline or Betadine for another hour. The rate of proteoglycan synthesis in the articular cartilage was then measured by uptake of 35SO4 for the next 16 hours. Cartilage metabolism was inhibited by all of the solutions even after a recovery time of 16 hours. The inhibition was by 5% for Ringer's solution, 10% for Ringer glucose (p < 0.01), 20% for saline and Ringer lactate (p < 0.001) and 55% for Betadine (p < 0.001). Ringer's solution is therefore the best choice for joint irrigation during arthroscopy or other procedures.

Animals↗
PubMed1993

Thionin staining of paraffin and plastic embedded sections of cartilage.

The usefulness of thionin for staining cartilage sections embedded in glycol methacrylate (GMA) and the effect of decalcification on cartilage sections embedded in paraffin and GMA were assessed. Short decalcification periods using 5% formic acid or 10% EDTA did not influence the staining properties or the morphology of cartilage matrix and chondrocytes. The standard stain safranin O-fast green for differential staining of cartilage was used as control in these experiments. Prolonged exposure of safranin O stained sections to fast green resulted in disappearance of the safranin O stained matrix, thereby hampering the quantitative measurement of negatively charged glycosaminoglycans (GAG). Thionin stained evenly throughout all cartilage layers, independent of the staining times. In contrast to safranin O, thionin did not show metachromasia in nondehydrated cartilage sections, which made it more suitable for assessing cartilage quality in GMA embedded cartilage. To evaluate the selectivity of thionin staining in cartilage, chondroitinase ABC and trypsin digestions were carried out. Thionin staining was prevented by these enzymes in the territorial matrix, representing the interlacunar network and the chondrocyte capsule. Staining with thionin of the interterritorial matrix was only slightly reduced, possibly representing keratan sulfate and hyaluronic acid in cartilage of elderly patients. Comparison of thionin stained GMA embedded cartilage with safranin O stained paraffin embedded sections showed significant similarity in optical densitometry, indicative of the specificity of thionin bound to negatively charged GAG in cartilage. In GMA embedded cartilage morphology was relatively intact compared to paraffin embedded sections due to less shrinkage of chondrocytes and the interlacunar network.

Aged↗
PubMed1992

The reliability of the Mankin score for osteoarthritis.

For the histopathological classification of the severity of osteoarthritic lesions of cartilage, the Mankin score is frequently used. A necessary constraint on the validity of this scoring system is the consistency with which cartilage lesions are classified. The intra- and interobserver agreement of the Mankin score was determined. The intra- and interobserver agreement of the 14-point Mankin score was adequate. Between observers 95% of differences were less than approximately 7 points. By a more strict definition of the elements of the Mankin score, the intraobserver differences were reduced only for some observers. The interobserver differences were only slightly reduced: between observers 95% of differences were less than approximately 6 points. We found the Mankin score to be an adequate histopathological tool.

Animals↗
PubMed1992

The effect of piroxicam on the metabolism of isolated human chondrocytes.

The effect of piroxicam on the metabolism of healthy and osteoarthrotic (OA) chondrocytes was studied in vitro. The chondrocytes were obtained from five healthy, five moderately OA, and four severely OA hips or knees. The chondrocytes were cultured in a high-density, short-term in vitro model. In this culture, the healthy chondrocytes as well as the OA chondrocytes retain their metabolic properties. Piroxicam was used in concentrations ranging from 0 to 10 micrograms/ml, which is comparable to the concentrations reached in vivo after oral administration. In cultures of healthy chondrocytes, piroxicam inhibited proliferation and synthesis of proteoglycans. The metabolism of moderately damaged chondrocytes was not influenced by piroxicam. In severely damaged chondrocytes, the proliferation was significantly inhibited by piroxicam. In order to avoid the possible negative side effects of piroxicam on the metabolism of healthy and severely OA chondrocytes, piroxicam treatment of an OA joint with synovitis should be restricted to the period of the effusion.

Cartilage, Articular↗
PubMed1991

[Alleviation of pain through posterolateral spondylodesis in patients with prolonged severe backache].

In order to study the effect of posterolateral spinal fusion on pain and returning to work of patients with chronic lower back pain, a retrospective study was carried out at the University Hospital, Maastricht. Fifty-nine patients with spondylolisthesis I or II, spondylolysis, hemisacralisation, disc degeneration and pseudoarthrosis after spinal fusion were treated by posterolateral spinal fusion. A questionnaire and visual analogue scale were used to assess the pain. The mean preoperative pain level was 8.6; the postoperative pain level was 4.5; 13 patients were without pain. Before operation 41 patients had a job; after operation 34 returned to work. Sex, age, period of complaints, indication or level of operation did not significantly affect the pain score. In particular cases, posterolateral spinal fusion diminishes pain in patients with spondylolisthesis I or II, spondylolysis or hemisacralisation in whom pain does not improve after non-operative therapy. After the operation most patients return to their work.

Adolescent↗
PubMed1990

The potential of adult human perichondrium to form hyalin cartilage in vitro.

The usefulness of adult human perichondrium for the restoration of articular cartilage defects depends on the potential to form hyalin cartilage. In order to evaluate the capacity of adult human perichondrium to form hyalin cartilage in vitro, perichondrium of the rib of eight adult human beings was cultured in vitro. After removal of residual cartilage, perichondrial explants were cultured for 7 or 10 days. The explants were histologically examined using specific stains to prove the presence of glycosaminoglycans (GAGs) normal for hyalin cartilage. Clear differentiation of perichondrial cells towards chondrocytes was noted. The chondrocytes synthesized new matrix substances normally present in hyalin cartilage. This investigation supports the usefulness of adult human rib perichondrium for the restoration of cartilage defects. Due to the enormous potential of the rib perichondrium to form hyalin cartilage in vitro, even defects in joints with a rather thick cartilage layer might be restored using this biological material.

Adult↗
PubMed1990

Perichondral grafting for cartilage lesions of the knee.

Twenty-five patients with 30 chondral lesions of the knee were treated with an autogenous strip of costal perichondrium. The graft was fixed to the subchondral bone with Tissucol (Immuno, Vienna), a human fibrin glue. The leg was then immobilised for two weeks followed by two weeks of continuous passive motion. Weight-bearing was permitted after three months. The mean knee score (Ranawat, Insall and Shine 1976) changed from 73 before operation to 90 one year after; in 14 patients evaluated after two years there was no decrease. In 28 cases the defect was completely filled with tissue resembling articular cartilage. We conclude that in most cases perichondral arthroplasty of cartilage defects of the knee gives excellent results.

Adolescent↗
PubMed1989

[Release of the lateral retinaculum of the knee in retropatellar chondropathy].

Retropatellar chondropathy is a frequent cause of pain in the knee; it usually runs a favourable natural course. When the symptoms interfere with work or sports, reduction of pain can be achieved by cleaving the lateral retinaculum (lateral release). To assess the results, a questionnaire was sent to 96 persons; 80 questionnaires could be evaluated. Only patients who had minor or no visible damage of the patellar cartilage were included in this study. Fifty-three patients reported improvement, in spite of which 34 had persistent mild symptoms which forced 12 of them to change the nature of their work. Thirty-seven patients had to change their sports activities in spite of the operation.

Adolescent↗
PubMed1986

Disk lesion of the wrist joint.

Thirty-three patients with lesions of the articular disk of the wrist joint were treated. Predictability of results is best when there is an isolated lesion without osteoarthritis or severe dislocation of the distal radioulnar joint. However, good results can be obtained in combined injuries (for example, after a Colles' fracture). Thirty of the thirty-three patients were satisfied with the results of their operation.

Adolescent↗