Biomedical subjects

L Ryd

Publications and source records attributed to L Ryd.

At least 73 records · Page 4Linked to original sources

PubMed1995

Roentgen stereophotogrammetric analysis as a predictor of mechanical loosening of knee prostheses.

The tibial components in 143 patients with total knee replacements performed before 1988 were assessed for micromotion using roentgen stereophotogrammetric analysis (RSA) over a period of 13 years. The fixation of the prostheses remained clinically sound in all cases, although revision had been required for other reasons in seven. In a second group taken from all cases with RSA available on our full database to 1990, 15 tibial components had been followed by RSA from the insertion until, 1 to 11 years after the initial arthroplasty, they were revised for mechanical loosening of the tibial component; 12 of these comprised all the loosenings in the base group, thus making a total of 155 consecutive cases, while an additional three were inserted after the base material had been compiled. The mean migration in the first group was about 1 mm at one year, but subsequent migration was slower, reaching a mean of about 1.5 mm after ten years. About one-third migrated continuously throughout follow-up, while two-thirds ceased to migrate after one to two years. In the revision group, 14 components had migrated continuously and at one year significantly more than those in the first group. One revision case lacked the crucial one-year follow-up and could not be classified. These findings suggest that mechanical loosening begins early in the postoperative period. Clinical symptoms which necessitate revision, seen at this stage in 20% of abnormally migrating tibial components, may not appear until up to ten years after the operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1994

Intraarticular injections of hyaluronan in patients with cartilage abnormalities and knee pain. A one-year double-blind, placebo-controlled study.

OBJECTIVE: To compare the effect of intraarticular injections of hyaluronan and placebo (vehicle, saline) in patients with knee pain on exertion and with joint cartilage abnormalities. METHODS: Fifty-two patients with arthroscopically verified deep cartilage fissures and villus-like flakes in the symptomatic knee were randomly assigned to receive intraarticular injections of 2.5 ml of either hyaluronan or vehicle, weekly for 5 weeks. The effect was evaluated by both primary and secondary parameters of efficacy at 2, 4, 13, 26, and 52 weeks. RESULTS: At the followup visits, both groups had improvement from baseline; however, there was no difference between the groups in any of the relevant variables at any time point. CONCLUSION: The effects of intraarticular hyaluronan do not differ significantly from those of placebo in patients with knee pain and cartilage disease.

Adult↗

PubMed1994

Stability of the elevated fragment in tibial plateau fractures. A radiographic stereophotogrammetric study of postoperative healing.

Five cases of fracture of the lateral tibial condyle of the split-depression type were treated by elevation of the depressed fragment, bone grafting and cancellous bone screws. During the operation, tantalum markers were inserted into the depressed fragment and the tibial metaphysis for radiographic stereophotogrammetric analysis. Postoperatively a plaster cast was applied for one month and weightbearing was not allowed for 3 months. In three cases, a depression of the elevated fragment, at the most 2.8 mm, recurred during the first month after operation. This was not considered to be significant and more aggressive postoperative mobilisation may be warranted.

Adult↗

PubMed1994

Surface characteristics following tibial preparation during total knee arthroplasty.

A clinical study, where flatness of the cut surface was quantified, was performed during 26 tibial bone cuts prepared for noncemented endoprosthetic components. Using sterilized dental imprint material and measured by the Zeiss Universal Measuring Centres (UMC) 850 (Oberkochen, Germany), the characteristics of the cut surface were defined. A clinically "flat" surface was found to be uneven with a maximum roughness of 1.71 mm (range, 1.06-2.57 mm), and defined as the distance between the uppermost and lowermost points. The flatness, defined as the standard deviation of the measuring points, was 0.26 mm (range, 0.16-0.38 min). This lack of smoothness creates gaps between the bone and prosthesis that are large enough to prevent direct bone contact when using noncemented fixation. This may be one reason why bony ingrowth is found inconsistently. The surface prepared by a 2-mm thick prototype saw blade was inferior to that created by a 1-mm blade.

Aged↗

PubMed1994

Cementation pressure in arthroplasty. In vitro study of cement penetration into femoral heads.

We analyzed the pressure needed for adequate cement penetration into the human arthrotic hip. 85 holes in 39 arthrotic femoral heads were cemented under predetermined pressures and times after cement mixing. Cement penetration correlated well to both pressure and time after mixing. No correlation to the degree of sclerosis was found. At 0.2 MPa, the average penetration into bone was 2 mm. However, 3-5 mm is considered the minimum depth for good fixation of an implant. To achieve a consistent adequate interdigitation, a pressure of approximately 0.3 MPa is recommended.

Acetabulum↗

PubMed1994

Improved bone cutting using a semirotating saw. A cadaver study of the cut surface on tibial condyles.

Cut surfaces on cadaver tibial bones prepared to receive an endoprosthetic tibial component, using an oscillating and a semirotating saw, were studied. Dental imprint material was used. The imprints were measured by a Zeiss UMC 850 to define the characteristics of the cut surface. The surface was smoother using the semirotating saw than the oscillating saw, with a mean maximum roughness of 1.46 mm and 2.36 mm, respectively. The corresponding flatnesses were 0.26 mm and 0.49 mm. The primary cut surface could not be improved during second cutting trials, which showed the importance of first correctly sawing in joint replacement surgery.

Bone and Bones↗

PubMed1994

On bias.

We performed a search in Medline to assess the quality of clinical journals in orthopedics from the point of view of study design. 3 levels of quality were chosen: prospective studies, random allocation or double-blind methods and randomized controlled trials; all entries were Medical Subject Headings (MeSH). Out of 25,538 articles indexed in Medline since 1966-1993 in the 8 most cited general orthopedic journals, 994 were indexed as prospective studies, while 138 were indexed as randomized, controlled trials. In recent years the number of well-designed articles has increased, as has the percentage. In a random check of 208 articles, approximately half were of a clinical type where these issues can be addressed. The agreement between the manual check and Medline indexing was good, but not perfect. It was concluded that the retrospective study representing clinical production control accounts for the vast majority of all published clinical articles in orthopedics. In recent years, a sharp increase in controlled trials had, however, occurred.

Double-Blind Method↗

PubMed1994

Effect of a cooled saw blade on prosthesis fixation. Randomized radiostereometry of 33 knee cases.

Tibial migration in 33 cementless total knee replacements, which were performed with a cooled saw blade vs. a conventional blade, was studied in a randomized prospective study using roentgen stereophotogrammetric analysis (radiostereometry). All cases were clinically successful after 2 years and inducible displacement was smaller in the group operated with the cooled saw blade. This group also had a tendency towards less continuous migration.

Aged↗

PubMed1993

Early postoperative fixation of tibial components: an in vivo roentgen stereophotogrammetric analysis.

The fixation of cemented and noncemented tibial components in 19 total knee arthroplasties was examined 3 to 10 weeks postoperatively with roentgen stereophotogrammetric analysis. Physiologic external forces were applied either in outward-inward rotation or as eccentric posterior loading generated by squatting. In one case there was no motion, while in the remaining 18 cases relative interface motion of up to 1.3 mm was found. In some cases, the largest motion was found during inward-outward rotatory stress, while in others, the largest motion was found during squatting. Posterior tilt was weakly correlated with posterior displacement of the femoral component on the tibia during squatting (r2 = 0.323, p < 0.05). For the noncemented cases, the initial fixation to bone was probably insufficient, and ingrowth of bone would not have been achieved. For the cemented cases, motion of the implant was reduced. Given the short postoperative time and the probable absence of any substantial fibrous tissue membrane, we suggest that the observed motion represented elastic deformation of the bone.

Aged↗

PubMed1993

A new radiographic method for detection of tibial component migration in total knee arthroplasty.

In a prospective study the accuracy of a new radiographic method, Matched Indicators for Radiographic Assessment (MIRA), used to assess tibial component migration in total knee arthroplasty was evaluated. Radiopaque markers were placed in the tibial component and the tibial metaphysis in a standardized way so that four vertical distances could be measured on standard radiographs. Subsidence during the first postoperative year was measured both with this new method and with roentgen stereophotogrammetric analysis in 27 Freeman-Samuelson total knee arthroplasties. The error of measurement of MIRA was determined using the known error of roentgen stereophotogrammetric analysis. The new method was found to be promising with an accuracy of 1 mm, and the correlation between MIRA and roentgen stereophotogrammetric analysis was high when subsidence exceeded this value. Therefore, subsidence of clinical importance should be detected with MIRA. The method is simple and well suited for routine follow-up examination of large patient materials.

Aged↗

PubMed1993

Inferior locking of the patella: a case report.

A 87-year-old woman with femoropatellar arthrosis sustained a fixed inferior traumatic locking of the patella with the knee in flexed position. After closed manipulation locking recurred and surgery was necessary to ensure smooth articulation.

Aged↗

PubMed1993

Migration of hydroxyapatite coated femoral prostheses. A Roentgen Stereophotogrammetric study.

We allocated randomly 27 patients undergoing 28 primary uncemented total hip replacements (THR) to receive prosthetic components of similar design with either plasma-sprayed titanium alloy (Ti) coating (n = 13) or hydroxyapatite (HA) coating (n = 15). After some exclusions, 15 of the patients (15 THR; 7 with HA- and 8 with Ti-coating) were followed by roentgen stereophotogrammetric analysis at 3, 6 and 12 months to measure migration of the femoral component. Twenty-six of the patients (26 THR) were followed clinically and by conventional radiography. All the femoral components had migrated at 3 months. From 3 to 12 months, the migration of Ti-coated components continued whereas the HA-coated components had stabilised. At 12 months there was significantly less migration of the HA-coated components (p < 0.05). The maximum subsidence was 0.2 mm in both groups. The Harris hip score was equal in the two groups preoperatively but at follow-up it was better in the HA-coated group (p < 0.05) and visual analogue scale scores showed that they had less pain (p < 0.05).

Aged↗

PubMed1993

Candida albicans arthritis in a nonimmunocompromised patient. Complication of placebo intraarticular injections.

A nonimmunocompromised 32-year-old man with arthrosis of the knee participated as a placebo control in a clinical trial of intraarticular injections of hyaluronan. After the fourth weekly injection of saline, he developed a warm and swollen knee, and synovial fluid cultures revealed growth of Candida albicans. Oral fluconazole treatment was instituted 2 weeks after onset of symptoms, but failed to eradicate the infection. The patient recovered after treatment with local and systemic amphotericin B, systemic 5-fluorocytosine and surgical synovectomy. Quantitation of joint cartilage proteoglycan fragments in synovial fluid indicated extensive breakdown of cartilage during the acute phase of arthritis but, parallel to clinical recovery, these levels returned to normal.

Adult↗

PubMed1993

Micromotion of a noncemented tibial component with screw fixation. An in vivo roentgen stereophotogrammetric study of the Miller-Galante prosthesis.

Micromotion of the tibial component was studied in ten cases of successful arthroplasty for gonarthrosis using the Miller-Galante total knee prosthesis with roentgen stereophotogrammetric analysis (RSA). In six of seven cases, there was a mean of 0.6-mm migration during the first year. Most of this migration occurred as tilt and rotation. Subsidence was seldom found. Inducible displacement was observed in seven cases after one year; in six, deflections were found. In five cases, the inducible displacement was small, approximately 0.3 mm, whereas the sixth case showed inducible displacement of 1.7 mm. The micromotion found in this study was smaller than has previously been reported for other noncemented prostheses. In some of these cases, the RSA data may be compatible with mechanical coupling of the prosthesis to the bone by bony ingrowth.

Aged↗

PubMed1993

99mTc-diphosphonate scintigraphy in successful knee arthroplasty and its relation to micromotion.

Nineteen tibial components after successful knee arthroplasty were studied with technetium 99m scintigraphy. All cases were also followed from the operation with roentgen stereophotogrammetric analysis (RSA). All but three cases became stable after an initial period of migration. Scintigraphic uptake was found in all cases, with a ratio as high as seven in the medial compartment and three in the lateral compartment. A group of cases with proven mechanical loosening showed an uptake ratio as high as 6.9 in the medial compartment and 5.5 in the lateral compartment. No correlation was found between scintigraphic uptake and alignment, whether cement was used, or the presence/absence of migration. Technetium 99m scintigraphy is not a useful method for assessing loosening in individual symptomatic cases of knee arthroplasty.

Aged↗

PubMed1992

The influence of metal backing in unicompartmental tibial component fixation. An in vivo roentgen stereophotogrammetric analysis of micromotion.

The fixation of the tibial component in 36 patients with conventionally cemented unicompartmental knee arthroplasties for femorotibial gonarthrosis was studied using roentgen stereophotogrammetric analysis (RSA). Twenty-four tibial components were all-polyethylene while 12 were metal-backed. The follow-up was for 6 years. Significant migration was detected for all cases but two and ranged from 0.3 mm to 5.4 mm. The greater part of the migration occurred during the first 1-2 years, after which two-thirds of the prostheses remained stable. Seven all-polyethylene components were subjected to a stress examination after 1-2 years and displacement, induced by external forces, was found in all seven. A strong correlation was found between the extension of the radiolucent line and the migration. Otherwise, neither demographic, clinical, nor radiographic data correlated with the RSA results. In this study metal backing did not have any influence on prosthetic fixation as measured by RSA.

Aged↗

PubMed1992

Temperature influence in different orthopaedic saw blades.

Laboratory tests were carried out on ox bone to evaluate the thermal effect of eight different saw blades while cutting cortical bone. These saw blades represented the usual clinical blades as well as saw blades specially manufactured in an attempt to decrease the temperature. Temperatures between 34 degrees C and 450 degrees C were registered in the saw blades. Only three measurements (of 219 tests) were below 44 degrees-47 degrees C, which is a critical limit for heat-induced bone necrosis. This test indicates that alternating saw blade design is not a way to control the temperature elevation during cutting of bone in orthopaedic procedures.

Bone and Bones↗

PubMed1992

Instability after anterior cruciate ligament rupture. Measurements of sagittal laxity compared in 11 cases.

Manual tests and 2 external devices were used together with roentgen stereophotogrammetry (RSA) and an active weight-bearing radiographic method to measure the sagittal laxity in 11 knees with anterior-cruciate-ligament rupture. In 5 knees no ligament surgery had been performed (unstable knees) and in 6 knees a reconstruction had been performed one year before the examination (stable knees). There were positive correlations between all methods, including the manual tests when all knees, both stable and unstable, were analyzed together. However, the mean values of the total displacement differed between the methods, especially when comparing the weight-bearing radiographs with the three other methods. Some knees with substantial displacement during passive loading did not show any displacement when weight bearing; the measurements thus depended on both the ligamentous laxity and the patient's neuromuscular control of the joint. When the stable knees were analyzed separately, higher mean values were recorded with the external devices than with RSA using 180 N load. This could be explained by an error from soft tissue deformation which added to the skeletal displacement when the external devices were used.

Adolescent↗