Biomedical subjects

S Toksvig-Larsen

Publications and source records attributed to S Toksvig-Larsen.

At least 19 recordsLinked to original sources

PubMed2001

The patella in total knee arthroplasty: resurfacing or nonresurfacing of patella.

Data from the Swedish Knee Arthroplasty Registry were analyzed to compare bi- and tricompartmental knee arthroplasties carried out in patients operated on for arthrosis in 1990-1996. Of the 16,607 primary arthroplasties that were carried out there were 5,139 with patellar replacement in the primary procedure and 10,928 without. By April 1998, 280 revisions were performed, 250 of these cases were analyzed in this study. Patella-related complications were commonly the reason for early revision: in 99 of the 168 knees with a primary bicompartmental procedure and in 36 of the 82 knees with a primary tricompartmental procedure. This presentation merely analyzes the extent of patellar problems in knee arthroplasty, as a detailed analysis of the causes of this common problem is not possible using data from a national multicenter study.

Arthroplasty, Replacement, Knee↗

PubMed2001

Analysis of the distribution and frequency of trisomy 7 in vivo in synovia from patients with osteoarthritis and pigmented villonodular synovitis.

Osteoarthritis (OA) and pigmented villonodular synovitis (PVNS) are disorders associated with trisomy 7. The aim of the present study was to determine the frequency and distribution of the cells with +7 in vivo by analyzing sections of paraffin-embedded synovia from patients affected by OA, PVNS, other forms of synovitis [hemorragic synovitis (HS) and chronic synovitis (CS)], and from individuals without joint disease. Fluorescence in situ hybridization (FISH), using a centromeric probe for chromosome 7, showed that the mean frequency of trisomic nuclei in 5-microm sections was highest in PVNS (9.0%), followed by CS (5.9%), OA (5.6%), and HS (4.6%), whereas trisomic nuclei were rare (0.7%) in normal tissue. When 8-microm sections were studied, the frequencies of trisomic cells in OA and control synovia increased to 6.7% and 1.5%, respectively. Trisomic nuclei were found in all cases, including those for which cytogenetic analysis of short-term cultures had not disclosed any trisomic cells. Overall, the trisomic cells were scattered within the tissue. However, small clusters of cells with +7 were found in three cases. By hematoxylin-eosin staining of the slides used for FISH analysis it could be shown that the clustered trisomic cells were proliferating synoviocytes within villous extensions of the synovial membrane.

Adult↗

PubMed2001

The tumor-associated gene HMGIC is expressed in normal and osteoarthritis-affected synovia.

Chromosomal rearrangements involving chromosome bands 12q13-15 are very frequent findings in benign solid tumors, and recently, the primary molecular target for these aberrations was identified as the gene HMGIC. However, mutations in this gene have also been observed in nonneoplastic tissues. In a previous study, we reported breakpoints within HMGIC of synovia affected by osteoarthritis (OA) in two cases with 12q15 aberrations. To analyze further the role of HMGIC in this disease, we have performed cytogenetic, fluorescent in situ hybridization (FISH), RNA, and protein expression analyses on synovial samples from patients with OA and individuals without signs of the disorder. Cytogenetic analysis of short-term cultured cells revealed clonal 12q13-15 aberrations in 2/36 cases of OA synovia and no rearrangement in any of the five controls. With FISH analysis, it was shown that the chromosomal breakpoints in the two aberrant cases were located outside the HMGIC locus. In contrast, at RNA and protein expression analyses, OA-affected as well as normal synovia displayed transcription and translation of the gene. We also analyzed whether immunoreactivity for HMGIC was associated with the proliferation-specific antigen Ki-67, but no correlation between the staining patterns of these proteins was observed. From the results of the present study, it is evident that expression of HMGIC cannot simply be considered a sign of neoplasia or an effect of proliferation.

Adolescent↗

PubMed2001

Fixation strength and pin tract infection of hydroxyapatite-coated tapered pins.

In a multicenter, prospective, randomized study, the biomechanical and clinical properties of the bone-pin interface were compared with standard tapered pins and hydroxyapatite-coated tapered pins implanted in patients who underwent femoral and tibial external fixation treatments. The results showed that the hydroxyapatite-coated tapered pins are clinically effective in improving the strength of fixation of the bonepin interface. This improvement corresponded to a lower rate of pin tract infection. In the hydroxyapatite-coated pin group, there were no differences in strength of fixation between the pins removed from the infected and uninfected pin tracts. In this pin group, the mean pin extraction torque was 531 +/- 225 Ncm in the infected pin tracts and 508 +/- 233 Ncm in the uninfected pin tracts. In the standard pin group, the mean pin extraction torque was 73 +/- 142 Ncm in the infected pin tracts and 211 +/- 216 Ncm in the uninfected pin tracts. The advantages provided by the hydroxyapatite-coated pins were higher in cancellous bone than in cortical bone.

Adult↗

PubMed2001

Trisomy 7 accumulates with age in solid tumors and non-neoplastic synovia.

Trisomy 7 is a common finding in benign and malignant solid tumors, in several non-neoplastic lesions (for example, osteoarthritis and rheumatoid arthritis), and in apparently normal tissues as well, suggesting that the occurrence of +7 might be associated with factors other than the disease process itself. To find out whether the frequency of +7 varies with a patient's age, we cytogenetically analyzed short-term-cultured synovial samples from elderly persons without signs of arthritis and from young patients affected by juvenile chronic arthritis (JCA). In normal synovia, gain of a chromosome 7 was present as a clonal change in five of 10 cases and in single cells in four of the five remaining cases. In synovia from patients with JCA, cells with +7 were detected in only one of nine cases, representing the oldest patient in the series. Furthermore, we reviewed the cytogenetic literature on tumors of the brain, breast, colon, kidney, lung, skin, thyroid, and upper aerodigestive tract. In the majority (six of eight) of these tumor types, the frequency of cases displaying a clone with +7 as the sole aberration increased with age. Taken together, the results presented here suggest that the acquisition of trisomy 7 in some neoplastic and non-neoplastic tissues might be associated with age rather than with disease. The finding of a completely different frequency distribution in two of the tumor types (tumors of the brain and the thyroid gland), however, emphasizes the heterogeneity of +7 and indicates that other, possibly tissue-specific, factors might influence the occurrence of this mutation.

Adolescent↗

PubMed2000

Digital automated RSA compared to manually operated RSA.

The accuracy of digital Roentgen stereophotogrammetric analysis (RSA) was compared to the accuracy of a manually operated RSA system. For this purpose, we used radiographs of a phantom and radiographs of patients. The radiographs of the patients consisted of double examinations of 12 patients that had a tibial osteotomy and of double examinations of 12 patients that received a total hip prosthesis. First, the radiographs were measured manually with an accurate measurement table. Subsequently, the images were digitized by a film scanner at 150 DPI and 300 DPI resolutions and analyzed with the RSA-CMS software. In the phantom experiment, the manually operated system produced significantly better results than the digital system, although the maximum difference between the median values of the manually operated system and the digital system was as low as 0.013mm for translations and 0.033 degrees for rotations. In the radiographs of the patients, the manually operated system and the digital system produced equally accurate results: no significant differences in translations and rotations were found. We conclude that digital RSA is an accurate, fast, and user friendly alternative for manually operated RSA. Currently, digital RSA systems are being used in a growing number of clinical RSA-studies.

Arthroplasty, Replacement, Hip↗

PubMed2000

The introduction period of unicompartmental knee arthroplasty is critical: a clinical, clinical multicentered, and radiostereometric study of 251 Duracon unicompartmental knee arthroplasties.

One hundred twenty-eight consecutive knees were operated on with the Duracon unicompartmental knee arthroplasty. Of 111 knees, followed 3 years (range, 1-6 years), 109 knees were satisfactory. Two knees were revised because of progression of osteoarthritis and inexplicable pain. Radiostereometric analysis in 49 knees showed a migration of 0.6 mm after 2 years. The magnitude of migration was lower in comparison with published series. In a multicenter study comprising 4 other hospitals, there were 8 revisions in 123 operated knees. The reasons were loosening, subsidence, or fracture. These revisions were within 1 year and mostly related to operative technique. Unicompartmental knee arthroplasty is a demanding procedure that needs special experience and includes a risk of early failures during the introduction of a system.

Aged↗

PubMed2000

Clodronate prevents prosthetic migration: a randomized radiostereometric study of 50 total knee patients.

In a double-blind study, we randomized 50 patients to receive peroral clodronate medication or placebo from 3 weeks before until 6 months after a total knee replacement with a cemented NexGen implant. Migration of the tibial components was measured by radiostereometry at 1 year. Clodronate reduced prosthetic migration, as measured by maximum total point motion, from 0.40 mm to 0.29 mm (p = 0.01). This confirms that the early postoperative migration is related to bone resorption and thus the biology of the bone bed. Since early migration is related to late loosening, 6 months of clodronate medication might reduce the risk of loosening.

Aged↗

PubMed2000

Hydroxyapatite-enhanced tibial prosthetic fixation.

Sixty-two knees (60 patients) were randomized to four noncemented groups. In Groups 1, 3, and 4, the bone cuts were made with a cooled saw blade. In Group 1, 15 patients were operated on with the porous coated Osteonic 7000 tibial component. In Group 2, 15 patients were operated on with the same tibial component as in Group 1 but with the use of a standard saw blade. In Group 3, 16 patients were operated on with the hydroxyapatite-coated Osteonic tibial component, and in Group 4, 16 patients were operated on with the hydroxyapatite Duracon tibial component. All patients were followed up clinically and with roentgenstereometric analysis. There were no differences among the groups regarding clinical outcome. One knee was revised (Group 2) after 1 year because of loosening of the tibial component. The maximum migration at 1 year was 1.7 mm in Group 1, 1.9 mm in Group 2, 1.3 mm in Group 3, and 1 mm in Group 4. At the 2-year followup, the migrations were 1.8 mm, 1.5 mm, 1.4 mm, and 1 mm in Groups 1, 2, 3, and 4, respectively. The inducible displacement that occurred at 1 year was 0.6 mm in Group 1, 0.5 mm in Group 2, 0.4 mm in Group 3, and 0.4 mm in Group 4. The hydroxyapatite coating had a strong positive effect on the tibial component fixation. No prosthesis in the hydroxyapatite groups showed continuous migration.

Aged↗

PubMed1999

Failure of partial cementation to achieve implant stability and bone ingrowth: a long-term roentgen stereophotogrammetric study of tibial components.

Thirty patients with gonarthrosis were operated on with the PCA primary total knee prosthesis and had the tibial component fixed to the bone by partial cementation. In the first two groups of patients, cementation was by a peripheral rim of high and low-viscosity cement, respectively. In the third group, the pegs were cemented with the low-viscosity cement. Follow-up was performed with use of clinical parameters and roentgen stereophotogrammetric analysis. Clinically, the series was successful apart from a problem with tibial component wear, necessitating revision in five patients. At 8 years, the mean Hospital for Special Surgery score was 81 points. Venn-diagram scores revealed four failures and three acceptable cases; the remaining cases were satisfactory. Apart from one loose patellar component, there was no mechanical loosening. Roentgen stereophotogrammetric analysis showed that the tibial components moved relative to the bone; this indicated fibrous tissue fixation, which was corroborated histologically in two patients. The objective, to achieve bone ingrowth, was thus not successfully met. Radiolucent lines were consistently seen, and their size correlated with the migration as measured by roentgen stereophotogrammetric analysis. Furthermore, five continuously migrating prostheses showed significantly larger radiolucent zones than the prostheses that migrated only initially, and they were less well bonded to the bone at 1 year. In conclusion, partial cementation does not appear to be a way to achieve bone ingrowth in porous-coated implants under load.

Aged↗

PubMed1999

Validation of a functional method for the estimation of hip joint centre location.

The present study assesses the accuracy with which the subject specific coordinates of the hip joint centre (HJC) in a pelvic anatomical frame can be estimated using different methods. The functional method was applied by calculating the centre of the best sphere described by the trajectory of markers placed on the thigh during several trials of hip rotations. Different prediction methods, proposed in the literature and in the present investigation, which estimate the HJC of adult subjects using regression equations and anthropometric measurements, were also assessed. The accuracy of each of the above-mentioned methods was investigated by comparing their predictions with measurements obtained on a sample of 11 male adult able-bodied volunteers using roentgen stereophotogrammetric analysis (RSA), assumed to provide the true HJC locations. Prediction methods estimated the HJC location at an average rms distance of 25-30 mm. The functional method performed significantly better and estimated HJCs within a rms distance of 13 mm on average. This result may be confidently generalised if the photogrammetric experiment is carefully conducted and an optimal analytical approach used. The method is therefore suggested for use in motion analysis when the subject's hip range of motion is not limited. In addition, the facts that it is not an invasive technique and that it has relatively small and un-biased errors, make it suitable for regression equations identification with no limit to sample size and population typology.

Adult↗

PubMed1999

Gait affects tibial component fixation.

The prognosis of fixation in patients with total knee arthroplasty was classified as either good or poor based on migration results over 4 to 8 years using roentgen stereophotogrammetry. Gait analysis with the Vicon system was performed in 27 asymptomatic patients (1 bilateral), selected according to gender, implant design, age, and fixation principle to form two equivalent groups with different prognoses. The poor prognosis group walked with a predominantly flexing moment and higher moment peaks in the sagittal plane compared with the good prognosis group, in which moments were abnormally small. We conclude that individual gait patterns and subsequent differences in joint loading affect tibial component fixation.

Aged↗

PubMed1999

Major bone transplantation in total knee arthroplasty: a 2- to 9-year radiostereometric analysis of tibial implant stability.

Eight total knee arthroplasties involving major bone grafting to repair noncontained defects of the proximal tibia were studied. In all knees, autologous bone was used. Cement was used for implant fixation. At follow-up evaluation 5 years after surgery, 7 knees had excellent results, and 1 had fair results; the mean Hospital for Special Surgery score was 84. Radiostereometric analysis showed a mean migration of 0.5 mm (range, 0.2-1.5 mm). None of the knees in which major structural autologous bone grafting was used showed increased micromotion of the adjacent tibial implant.

Aged↗

PubMed1999

Preoperative bone mineral density of the proximal tibia and migration of the tibial component after uncemented total knee arthroplasty.

Twenty-two patients with primary osteoarthrosis of the knee all operated on with insertion of an uncemented total knee arthroplasty had a preoperative measurement of bone mineral density (BMD) in the coronal plane of the proximal tibia performed by dual-photon absorptiometry. Postoperatively and with follow-up after 6 weeks (n = 21), 1 year (n = 22), and 3 years (n = 19), radiographs suitable for radiostereometric analysis of the tibial component migration were obtained. One year postoperatively, stress examinations were performed with the aim of measuring inducible displacement of the tibial component. Most of the migration, expressed as maximal total point motion (MTPM), occurred during the first year with an average migration of approximately 1 mm. Regression analysis showed a positive relation between BMD and MTPM after 6 weeks (P = .03, r = .47), 1 year (P = .0005, r = .68), and 3 years (P = .02, r = .54). Inducible displacement did not reveal any significant relation to BMD. MTPM between 1 and 3 years, which is the clinically most important parameter with respect to later loosening of the tibial component, showed a negative relation to BMD (P = .04, r = -.47). Thus, tibial components of knees with preoperative high tibial BMD showed less continuous migration.

Aged↗

PubMed1999

Open-wedge osteotomy by hemicallotasis or the closed-wedge technique for osteoarthritis of the knee. A randomised study of 50 operations.

We describe the results of 50 operations carried out on 46 patients with medial osteoarthritis of the knee of Ahlbäck grade 1 to 3. Patients were randomised either to a closed-wedge high tibial osteotomy (HTO) or an open-wedge procedure based on the hemicallotasis technique (HCO). Their median age was 55 years (38 to 68). The preoperative median hip-knee-ankle (HKA) angle was 171 degrees (164 to 176) in the HTO group and 173 degrees (165 to 179) in the HCO group. After six weeks, the median HKA angle was 185 degrees (176 to 194) in the HTO group and 184 degrees (181 to 188) in the HCO group. In the HTO group, seven patients were within the range of 182 degrees to 186 degrees compared with 21 in the HCO group (p < 0.001). One year later, ten HTO patients were within this range while the HKA angulation in the HCO group was unchanged. At two years the numbers were 11 and 18, respectively. We evaluated the clinical results on the Hospital for Special Surgery, Lysholm and Wallgren-Tegner activity scores, and patients completed part of the Nottingham Health Profile questionnaire. An impartial observer at the two-year follow-up concluded that all scores had improved, but found no clinical differences between the groups.

Adult↗

PubMed1999

Hemicallotasis open-wedge osteotomy for osteoarthritis of the knee. Complications in 308 operations.

We studied the complications after open-wedge osteotomy by hemicallotasis in 308 consecutive patients, most of whom had osteoarthritis of the knee. The participating surgeons, who worked at 17 hospitals, used their discretion in selecting patients, operating techniques and external fixators. The general complications included 11 cases of deep-vein thrombosis (4%), six of nonunion (2%) and one of septic arthritis of the knee. There were technical complications in 13 patients (4%). In 157 patients (51%) pin-site infections were recorded; of these, 96% were minor and responded to wound toilet and antibiotic treatment. A total of 18 revision procedures was carried out.

Adolescent↗

PubMed1999

Tourniquet release for hemostasis increases bleeding. A randomized study of 77 knee replacements.

We conducted a prospective, randomized study of 77 primary knee replacement operations on 75 patients (52 women), with a mean age of 71 years, to evaluate the effect of tourniquet release for hemostasis on blood loss and transfusion requirements. The operations were all done with spinal anesthesia and the use of a midline skin incision and medial parapatellar approach. In group I, the tourniquet was released for hemostasis before the wound was closed. In group 2, the tourniquet was first released after the wound was closed and a compressive dressing had been applied. The total intra- and postoperative blood losses were, on average, 858 mL (SD 443) in group I and 589 mL (347) in group 2 (p = 0.01). The median units of blood given and the postoperative decreases in hemoglobin values were similar in both groups. In a subgroup of 45 cementless prostheses, the 25 patients with prostheses allocated to group 1 lost 1022 mL (397) blood, compared to 646 mL (333) by the 20 patients with prostheses in group 2 (p = 0.01). Our findings speak against the efficacy of tourniquet release for hemostasis in knee replacement surgery.

Adult↗

PubMed1999

Patient satisfaction, function and return to work after knee arthroplasty.

We investigated the working status during 2 years before and 2 years after primary knee prosthetic operation for arthrosis in order to identify preoperative factors predicting patient satisfaction, function and working capacity. 162 patients (86 women) younger than 60 years of age when operated on with a knee prosthesis during 1993 were studied. 91% of the patients returned a Nottingham Health Profile (NHP) questionnaire, and the Social Insurance Office could supply data on all patients. There was a positive association between the duration of pre- and postoperative sick-leave in the patients who returned to work. Preoperative sick-leave longer than 180 days increased the risk of postoperative disability pension, which was not found to be influenced by the grade of the work. Among the 52 patients who returned to work postoperatively, all 6 NHP functional categories were better in the patients with less than 180 days of preoperative sick-leave than in the patients with more than 180 days of preoperative sick-leave. The overall patient satisfaction was greater among patients who went back to work postoperatively. We conclude that long sick-leave before a knee prosthetic operation increases the risk of long postoperative sick-leave and disability pension and impairs the quality of life.

Arthritis↗