Total hip replacement with a zirconium oxide ceramic femoral head: a randomised roentgen stereophotogrammetric study.

We investigated the wear characteristics and clinical performance of four different total hip joint articulations in 114 patients. Wear and migration was measured by roentgenstereophotogrammetric analysis at five years or at the last follow-up. The mean annual wear was 0.11 mm for a stainless steel/Enduron articulation, 0.34 mm for stainless steel/Hylamer cup, 0.17 mm for zirconium oxide ceramic/Enduron and 0.40 mm for zirconium oxide ceramic/Hylamer. The difference between the groups was significant (p < 0.008) except for stainless steel/Hylamer vs zirconium oxide ceramic/Hylamer (p = 0.26). At present, 12 patients have undergone a revision procedure, four at five years and eight thereafter. No patient who received a stainless steel/Enduron articulation at their primary replacement required revision. Conflicting results have been reported about the performance of the zirconium oxide ceramic femoral head, but our findings suggest that it should not be used with a polymethylmethacrylate acetabular component. Hylamer has already been withdrawn from the market.

Accuracy and precision of radiostereometric analysis in the measurement of THR femoral component translations: human and canine in vitro models.

Radiostereometric analysis (RSA) is used to measure translations of joint replacement components with respect to the host bone in vivo. We used two cadaveric models of hip arthroplasty, one human and one canine, to evaluate the accuracy and precision of RSA-based estimates of translations of the femoral component with respect to the femur under ideal conditions. The femoral components were attached rigidly to a micrometer stage that provided standard displacements in increments of 25 and 50 microm in the interval from zero to 500 microm along three orthogonal axes. Radiostereometric examinations were performed for each increment. Accuracy was calculated as the 95% prediction intervals from regression analyses between the measured and actual displacements. Precision was evaluated as the standard deviation of five repeated measurements of a 200 microm displacement along each axis. Both accuracy and precision were best along the longitudinal axis, with a prediction interval of +/-47 microm in the human model and +/-45 microm in the canine model and a standard deviation of 30 microm in the human model and 40 microm in the canine model. The use of only the prosthetic head as a landmark (as opposed to three markers placed on the femoral stem) led to a 3-fold larger prediction interval in the human model and a 2-fold greater prediction interval in the canine model.

Can an external frame fixation reduce the movements in the sacroiliac joint? A radiostereometric analysis of 10 patients.

To evaluate whether a Hoffmann-Slätis frame can reduce movements in the sacroiliac joints, 10 patients (7 women) with severe posterior pelvic pain of long duration were externally stabilized. The movements were analyzed with radiostereometric analysis (RSA) in supine and standing positions, preoperatively and postoperatively with the frame applied. In 2 patients, there was no reduction in the movements with the frame, perhaps because it was not properly tightened. In the remaining 8 patients, the median reduction in rotation was 55% on the left side and 63% on the right side around the helical axes, and 74% around the x-axes on the left side and 66% on the right side. Our data suggest that external fixation using the Hoffmann-Slätis frame, substantially reduces sacroiliac joint mobility in some patients, which must be considered when using the frame as a diagnostic tool. Pre-stressing the frame by tightening the vertical bars before the compression bar is applied is recommended to reduce the risk of this shortcoming.

Bone graft fixation in anterior cruciate ligament reconstruction evaluated by radiostereometric analysis.

For most anterior cruciate ligament reconstruction techniques, the tensile strength of the ligament substitutes and the surgical methods of fixation have been examined. In the present study seven consecutive patients with a chronic anterior cruciate ligament deficiency, who were reconstructed with a bone-patellar tendon-bone graft, were followed. The migration of the bone blocks was examined with radiostereometric analysis immediately postoperatively and after 3 and 12 months. The median migration of the bone blocks in the femur was 0.4 mm and in the tibia 0.4 mm. Clinical examination was undertaken preoperatively and one year postoperatively. We conclude that the use of interference screws seems to be a reliable method for fixation in anterior cruciate reconstruction and that healing of the bone blocks occurs during the first three postoperative months.

Hydroxyapatite augmentation of the porous coating improves fixation of tibial components. A randomised RSA study in 116 patients.

In a single-blind, randomised series of knee replacements in 116 patients, we used radiostereometric analysis (RSA) to measure micromotion in three types of tibial implant fixation for two years after knee replacement. We compared hydroxyapatite-augmented porous coating, porous coating, and cemented fixation of the same design of tibial component. At one to two years, porous-coated implants migrated at a statistically significantly higher rate than hydroxyapatite-augmented or cemented implants. There was no significant difference between hydroxyapatite-coated and cemented implants. We conclude that hydroxyapatite augmentation may offer a clinically relevant advantage over a simple porous coating for tibial component fixation, but is no better than cemented fixation.

Fixation of the tibial component of total knee arthroplasty after high tibial osteotomy: a matched radiostereometric study.

To assess migration of the tibial component we used roentgen stereophotogrammetric analysis in 40 patients who had had a total knee arthroplasty after failure of a closing wedge osteotomy and compared them with 40 matched patients after primary total knee arthroplasty. We found no difference in migration over time or in the tendency for continuous migration between the two groups. There were no differences in alignment or position of the knee prosthesis or in the clinical outcome. Our findings show that revision of a failed high tibial osteotomy to a total knee arthroplasty is effective.

Wear in uncemented porous and cemented polyethylene sockets: a randomised, radiostereometric study.

We used radiostereometric analysis to compare wear rates between uncemented porous sockets and cemented all-polyethylene sockets in a series of 102 hips randomised for either a Harris-Galante or a Charnley cup. Wear was evaluated in 95 hips at a mean of five years (2 to 7). All hips had a cemented, 22 mm head mono-bloc Charnley stem. The mean annual wear rate was 0.09 mm in the Charnley sockets and 0.10 mm in the Harris-Galante sockets, with no statistically significant differences in wear, migration or rotation. We conclude that, up to five years, the wear characteristics of the modular and porous Harris-Galante socket resemble that of the Charnley socket.

Migration of porous press-fit cups in hip revision arthroplasty. A radiostereometric 2-year follow-up study of 60 hips.

The migration of 60 press-fit cups fixed with screws was evaluated by radiostereometric analysis for 2 years in 57 patients revised because of aseptic loosening. The mean proximal migration of the cup center increased continuously up to 0.36 mm (range, 0.0-1.6 mm), whereas the migration in the other directions reached a level at 0.3 to 0.4 mm after 6 months. Mean rotations of less than 1 degree were recorded. Factors influencing motions were cup size, use of bone-grafts, and position of the cup center in the vertical and horizontal directions. Compared with previous stereoradiographic studies of cemented revisions, the migration of the press-fit cup was smaller, however, still higher than previously reported for uncemented cups of the same design used in primary surgery.

Migration and wear of a hydroxyapatite-coated hip prosthesis. A controlled roentgen stereophotogrammetric study.

A consecutive series of 30 total hip replacements using a hydroxyapatite (HA)-coated, modular implant (Omnifit) was followed clinically and by roentgen stereophotogrammetric analysis for two years and compared with two control groups, one of 27 cemented Charnley sockets and one of 40 cemented Charnley stems. Omnifit sockets with a central gap between the dome of the socket and the acetabular bone in the postoperative radiographs, migrated less than sockets without such gaps (p = 0.01). After adjustment for patient-related factors (age, gender and weight), no significant difference was found between the two prostheses with respect to micromotion and wear. We conclude that the early fixation of the HA-coated Omnifit prosthesis compares with that of the cemented Charnley prosthesis.

Appositional bone bridging of primary gaps in the dome area of uncemented, porous acetabular components.

Reported here are two cases of primary hybrid arthroplasties using a cemented stem and an uncemented, porous acetabular component. Because of the configuration of the acetabula, a residual central gap remained after implantation of the socket. Unimpacted grafts were used to fill the spaces. The gaps, amounting to 4 to 5 mm on the postoperative radiographs, had disappeared at the 30-40-month follow-up examination, with no radiolucent lines at the bone-implant interface. Both sockets were evaluated by roentgen stereophotogrammetric analysis for 2 years, and by using this technique for detecting micromovements, central migration as a reason for the disappearance of the gaps was precluded. Bony apposition of primary gaps of up to 5 mm in the central area of well-fixed porous acetabular components seems possible.

Migration of uncemented, long-stem femoral components in revision hip arthroplasty. A 2-8 year clinical follow-up of 45 cases and radiostereometric analysis of 13 cases.

We reviewed after 48 (24-90) months the clinical results in 45 cases of revision hip arthroplasties where an uncemented, long-stem femoral prosthesis (BIAS, Zimmer) had been used. A subgroup of 13 cases was followed with radiostereometric analysis (RSA) for 2 years. 3/45 cases had been revised, another 12 had unsatisfactory pain scores. The median Harris score was 69 (26-99). 12/13 stems migrated; 11 subsided 4.1 (0.4-7.9) mm, and 8 migrated posteriorly 2.9 (1.9-9.6) mm. The poor clinical results and large migrations speak against the use of this prosthesis in revision hip arthroplasty.

Migration of the Charnley stem in rheumatoid arthritis and osteoarthritis. A roentgen stereophotogrammetric study.

Migration of 65 Charnley stems implanted with modern cementing techniques was studied by roentgen stereophotogrammetry. There were 25 patients with rheumatoid arthritis (RA) and 40 with osteoarthritis (OA) followed up for two years. In 43 cases a bone sample for histomorphometric analysis was obtained from the femur during the operation. In 22 cases the mean subsidence of the prosthetic head was 0.40 mm and in 20 the mean posterior migration was 1.25 mm. There was no difference in migration between the two diagnostic groups (p = 0.8) after adjusting for variations in gender, age and weight. Male gender was associated with increased subsidence (p = 0.006). Histological examination showed that the RA series had more osteoid surface (p = 0.04), but neither this, nor any of the other histomorphometric variables, influenced migration. These results suggest that, unlike the acetabular socket, the cemented Charnley femoral component is equally secure in osteoarthritis and in rheumatoid arthritis, and that its initial fixation is not influenced by the quality of the local cancellous bone. Our results provide data with which the early performance of new prosthetic designs and fixation methods can be compared.

Osteolysis, wear and failure of a migrating acetabular component. A roentgen stereophotogram case report.

The migration of an acetabular component, revised 12 years postoperatively, was clearly detectable within the first year after operation by roentgen stereophotogram analysis. The failure was probably the result of an early initiated prosthetic loosening.

Micromotion of the acetabular component and periacetabular bone morphology.

The quality of the periacetabular bone might be an explanation for the increase in the rate of socket loosening seen radiographically in patients with rheumatoid arthritis as compared with patients with osteoarthrosis. Early implant micromotion, as measured by roentgen stereophotogrammetric analysis, is of predictive value with regard to long time retention. For uncemented porous sockets, the initial fixation might be decisive for the degree of bone ingrowth. Roentgen stereophotogrammetry was used to study cemented Charnley acetabular components in 32 hips with rheumatoid arthritis and 30 hips with osteoarthrosis, and uncemented Harris-Galante acetabular components in 19 hips with osteoarthrosis. Micromotions as long as 24 months after surgery were related to the periacetabular cancellous bone quality, as assessed by histomorphometric methods from samples taken during surgery. Acetabular components migrated more in hips with rheumatoid arthritis than in those with osteoarthrosis (p < 0.04). Hips with rheumatoid arthritis had approximately 4 times more nonmineralized bone than hips with osteoarthrosis (p < 0.0002). However, within each diagnostic group, no correlation was found between migration and the degree of mineralization (r < or = 0.24, p > or = 0.07). Migration of uncemented acetabular components did not correlate with the histomorphometric variables (r < or = 0.20, p > or = 0.42). Histomorphologic characteristics of the periacetabular trabecular bone do not seem to be of importance for acetabular component micromotion.

Cemented versus uncemented socket in hip arthroplasty. A radiostereometric study of 60 randomized hips followed for 2 years.

60 patients with arthrosis who received a Charnley total hip replacement were randomly assigned to either an uncemented porous Harris-Galante type I socket or a cemented all-polyethylene Charnley socket. Socket migration and rotation were studied by radiostereometry (RSA) for 2 years. After 2 years, all sockets were still in situ. There was no difference in migration or rotation between the 2 socket designs, nor was there any difference in pain or function. We conclude that the initial fixation of the Harris-Galante socket resembles that of the Charnley socket.

Periarticular bone in rheumatoid arthritis versus arthrosis. Histomorphometry in 103 hip biopsies.

Histomorphologic differences of the periarticular bone in rheumatoid arthritis (RA) and osteoarthrosis (OA) may be of importance for long-term prosthetic fixation. We have evaluated bone specimens, obtained during total hip replacement from an acetabular and a femoral biopsy site, in 42 RA-hips and 61 OA-hips. In both groups the bone turnover was increased in the acetabulum compared to that in the femur. In the acetabulums the total trabecular bone volume was equal, but osteoid volume, osteoid surface, resorptive surface, and the appositional rate were increased in RA. On the femoral side, only the osteoid volume was higher in RA. The increased bone turnover with a greater amount of unmineralized tissue, as well as resorptive activity in the acetabulum, may be of importance for the higher rate of acetabular component migration and loosening after total hip replacement in RA.

Migration of acetabular components, inserted with and without cement, in one-stage bilateral hip arthroplasty. A controlled, randomized study using roentgenstereophotogrammetric analysis.

Twenty-one patients who had primary osteoarthrosis were managed with a bilateral total hip arthroplasty with insertion of a Charnley femoral component. In each patient, one hip was randomly allocated to have a Harris-Galante acetabular component inserted without cement, and the contralateral hip was treated with an all-polyethylene Charnley acetabular component fixed with cement. The clinical result was satisfactory in all patients. All forty-two hips were followed, with respect to migration of the acetabular component, with use of roentgenstereophotogrammetric analysis for a median of twenty-seven months (range, twenty-three to forty-nine months). Each patient served as his or her own control. Maximum migration in any direction was 1.7 and 2.1 millimeters, and maximum rotation was 2.2 and 2.0 degrees for the Harris-Galante and Charnley acetabular components, respectively. There was no significant difference in migration between the two designs of acetabular components (p = 0.98, p = 0.75, and p = 0.06 for the transverse, longitudinal, and sagittal axes, respectively). However, the Harris-Galante acetabular components rotated significantly more than the Charnley acetabular components around two of the three axes (p = 0.008, p = 0.08, and p = 0.03 for the transverse, longitudinal, and sagittal axes, respectively). The Charnley hip implant has been used clinically for a long time, with successful results. Comparison of new designs of implants with the Charnley prosthesis is therefore important. Roentgenstereophotogrammetric analysis provides a potential for detection of problems with fixation at an early stage rather than after long-term follow-up. No major difference in terms of skeletal fixation was found between the two designs of components after short to medium-term follow-up.

Improved radiographic survival of the Charnley prosthesis in rheumatoid arthritis and osteoarthritis. Results of new versus old operative techniques in 402 hips.

Two hundred one consecutive, primary, noninfected Charnley (Thackray, Leeds) hip arthroplasties, implanted from 1968 to 1985 due to adult-onset rheumatoid arthritis, were matched in pairs with respect to year of operation, age, and sex with 201 Charnley prostheses implanted due to osteoarthritis. The 10-year survival estimate for nonrevisions was 95% in the rheumatoid group and 89% in the osteoarthritic group. Using definite radiographic loosening as a determinant, the 7-year survival rate for stems increased from 80% to 96% for both groups after the introduction of new cementing techniques, and the relative risk for stem loosening was decreased to one fifth. In the rheumatoid arthritis group, the 7-year radiographic socket survival increased from 87% to 96%, an increase ascribed to the overall effect of the introduction of flanged sockets, bone-grafts in acetabular protrusion, the rejection of the pilot hole technique, and improvements in the cement handling technique. In the osteoarthritis group the radiographic socket survival rate at 7 years was 97% and at 10 years was 95%.