| 1. |
- Bragdon, Charles R, 1959, et al.
(författare)
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Standing versus supine radiographs in RSA evaluation of femoral head penetration
- 2006
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Ingår i: Clin Orthop Relat Res. - 0009-921X. ; 448, s. 46-51
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of polyethylene acetabular component wear in total hip arthroplasties commonly is performed using serial radiographs of the hip by measuring the change in the location of the center of the femoral head in relation to the acetabular component. Of the different methods currently used for this purpose, radiostereometric analysis (RSA) is considered the most accurate and precise. In all such radiographic studies, it is assumed the femoral head is seated into the deepest portion of the acetabular component during all radiographic examinations. Although most radiographs used for wear measurements are taken with the patient supine, we questioned whether standing radiographs, with substantial joint load, are better suited for these measurements. We evaluated two groups of patients having total hip arthroplasty who had radiostereometric radiographs taken in supine and standing positions. The average femoral head penetration that occurred between the 6-month and 2-year time interval was measured with radiographs taken in the standing or supine position. We found no difference between the average total femoral head penetration when using supine or standing radiographs.
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| 2. |
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| 3. |
- Digas, Georgios, 1963, et al.
(författare)
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Addition of fluoride to acrylic bone cement does not improve fixation of a total hip arthroplasty stem
- 2006
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Ingår i: Clin Orthop Relat Res. - 0009-921X. ; 448, s. 58-66
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Tidskriftsartikel (refereegranskat)abstract
- Improved fixation to bone is vital for improving the long term success of cemented implants. Addition of fluoride to acrylic bone cement may be one way to improve the quality of the bone cement interface and thereby reduce the risk of loosening. Ninety patients (97 hips) with a median age of 70 years (range, 31-81 years) scheduled for total hip arthroplasty were randomized to receive a stem fixed with fluoride-containing acrylic bone cement or conventional acrylic bone cement. Fixation and bone remodeling around the femoral component was studied with radiostereometry and dual-energy xray absorptiometry up to 5 years after the operation in 73 patients (77 hips). Radiostereometric evaluation at 5 years revealed no differences in stem migration (subsidence/lift-off) or rotations. The stem subsidence inside the mantle was similar in the two groups. At 5 years the study group had lost more bone mineral in Gruen regions 5 and 7 than the controls. The Harris hip and pain score did not differ. Use of fluoride containing bone cement did not improve the stem fixation compared with a conventional cement used up to 5 years, but resulted in more pronounced loss of bone mineral density in the medial cortex. LEVEL OF EVIDENCE: Therapeutic Level I. See Guidelines for Authors for a complete description of levels of evidence.
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| 4. |
- Digas, Georgios, 1963, et al.
(författare)
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Bioactive cement or ceramic/porous coating vs. conventional cement to obtain early stability of the acetabular cup. Randomised study of 96 hips followed with radiostereometry
- 2004
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Ingår i: J Orthop Res. - : Wiley. - 0736-0266. ; 22:5, s. 1035-43
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Tidskriftsartikel (refereegranskat)abstract
- Ninety patients (96 hips) scheduled for THA were stratified to fixation of the acetabular component in three main groups of about equal size. Fluoride cement, porous coated press-fit cup with ceramic coating or Palacos cum Gentamicin cement were used. All patients received Spectron EF stem. The migration of the cups and the femoral head penetration into the socket were measured with radiostereometric analysis. At 2 years the choice of fixation did not influence the migration or rotation of the cup. Patients with compromised bone quality showed increased three-dimensional (3D or total) migration. Proximal and 3D penetration rates were increased in cemented compared with the uncemented cups (p<0.001), which probably not could be related to the choice of fixation. Appearance of radiolucent lines was almost equal in the two cemented groups. Uncemented cups had less radiolucent lines at 2 years. Fluoride containing cement or uncemented fixation did not improve the early postoperative stability of the socket.
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| 5. |
- Digas, Georgios, 1963, et al.
(författare)
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Different loss of BMD using uncemented press-fit and whole polyethylene cups fixed with cement: repeated DXA studies in 96 hips randomized to 3 types of fixation
- 2006
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Ingår i: Acta Orthop. - : Medical Journals Sweden AB. - 1745-3674. ; 77:2, s. 218-26
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In cemented THA, aseptic loosening of the cup is more common than loosening of the stem, while periprosthetic osteolysis of the socket resulting in difficult reconstruction problems has emerged as the most significant problem with cementless cup fixation. PATIENTS AND METHODS: 90 patients (96 hips) scheduled for THA were stratified in three groups according to the method of fixation of the acetabular component: acrylic bone cement with fluoride (Cemex-F), porous-coated press-fit cup with ceramic coating (Trilogy, uncemented) and acrylic cement with gentamicin (Palacos). All patients received the Spectron EF stem. Acetabular bone mineral density was measured with dual-energy X-ray absorptiometry (DXA) 1 week postoperatively, and after 12 and 24 months. The periprosthetic BMD was evaluated in 5 ROIs positioned around the acetabular component. RESULTS: In the uncemented sockets, the BMD had decreased proximally and medially to the cup after 2 years. The difference was significant in the proximal region as compared to the control group (Palacos). No difference was noted between the 2 groups with cemented components after 2 years. Stepwise linear regression analysis showed that loss of periprosthetic BMD in the proximal high-pressure region after 2 years increased with higher postoperative BMD and when the uncemented design had been used. INTERPRETATION: Contrary to previous studies of cemented stems, the use of fluoride cement did not influence the periprosthetic BMD 2 years after the examination. Increased loss of BMD with use of uncemented press-fit cups in the region in which osteolytic lesions are commonly found suggests that stress shielding may initiate the development of this complication. Longer follow-up will, however, be necessary to substantiate this hypothesis.
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| 6. |
- Digas, Georgios, 1963, et al.
(författare)
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Five-year DEXA study of 88 hips with cemented femoral stem
- 2009
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Ingår i: International Orthopaedics. - : Springer Science and Business Media LLC. - 0341-2695 .- 1432-5195. ; 33:6, s. 1495-500
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Tidskriftsartikel (refereegranskat)abstract
- We performed repeated dual-energy X-ray absorptiometry (DEXA) measurements over five years in a homogeneous patient population to study the effect of a cemented stem on proximal femoral bone remodelling. Data from 88 patients (88 hips) implanted with total hip arthroplasty (THA) prostheses were extracted from three randomised studies. Femoral bone mineral density (BMD) was measured using a Lunar DPX-IQ densitometer for five years postoperatively. At one year the BMD changes had decreased between -2.0% [region of interest (ROI) 1] and -11.5% (ROI 7). During the follow-up period the BMD initially increased during the second year and thereafter decreased again in ROIs 5, 6 and 7. The loss of BMD at five years was more pronounced in region 7 (12.9%) and decreased with increasing age, total hip replacement (THR) on the right side and decreasing weight of the patient. We found that after the initial phase of early bone loss a period of recovery follows. Thereafter the BMD decreases again, which probably reflects the normal ageing of bone after uncomplicated cemented THA.
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| 7. |
- Digas, Georgios, 1963, et al.
(författare)
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Fluoride-containing acrylic bone cement in total hip arthroplasty. Randomized evaluation of 97 stems using radiostereometry and dual-energy x-ray absorptiometry
- 2005
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Ingår i: J Arthroplasty. - : Elsevier BV. - 0883-5403. ; 20:6, s. 784-92
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Tidskriftsartikel (refereegranskat)abstract
- Ninety patients (97 hips) scheduled for total hip arthroplasty were stratified to fixation of the femoral component using fluoride-containing cement or Palacos with gentamicin. Whole polyethylene Reflection and press-fit Trilogy cups were used. All patients received Spectron EF stem. The micromotions of the stem were measured with radiostereometric analysis and the periprosthetic bone mineral density with automatic and manual dual-energy x-ray absorptiometry (DEXA) analysis. At 2 years, the choice of cement did not influence the subsidence or rotations of the stem. The DEXA analysis revealed more loss of periprosthetic bone mineral density in fluoride cement group. We speculate that forming of fluorapatite crystals, toxic effects of the fluoride, or lower radiopacity of the fluoride cement might explain this finding. According to our study with 2-year of follow-up, there is no obvious advantage of addition of fluoride to acrylic bone cement when used to fixate the femoral component in total hip arthroplasty.
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| 8. |
- Digas, Georgios, 1963, et al.
(författare)
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Inducible Displacements of the Cup and the Femoral Head During Active Range of Motion: Dynamic RSA Studies of Cemented Total Hip Replacements
- 2013
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Ingår i: Journal of Orthopaedic Research. - : Wiley. - 0736-0266. ; 31:11, s. 1686-1693
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated changes in position of the femoral head relative to the cup and of the cup relative to the pelvis in total hip replacement patients during hip motion 2 years postoperatively. Two patient groups with nine patients in each group were studied. Hip motions, translations of the femoral head center, and cup displacements were recorded with dynamic radiostereometric examination (RSA, 2exposures/s) during abduction in Group 1 and with use of static RSA exposures at increasing flexion of the hip in Group 2. Conventional radiographic examinations were used to evaluate any radiolucent lines around the cups at 2 years. During active abduction the femoral head center moved medially (median 0.04mm) and the cup tilted anteriorly (median 0.09mm). Increments in radiolucent lines at 2 years correlated to medial femoral head penetration, posterior tilt, and retroversion of the cup at 20 degrees of abduction. The extension of radiolucent lines at 2 years showed a positive correlation with proximal inducible displacement of the cup and posterior translation of the femoral head center at maximum hip flexion. Our observations may be of value in understanding the pathogenesis of the loosening process and may be used to facilitate the development of prosthetic designs that optimize hip kinematics. (c) 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1686-1693, 2013
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| 9. |
- Digas, Georgios, 1963
(författare)
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New polymer materials in total hip arthroplasty. Evaluation with radiostereometry, bone densitometry, radiography and clinical parameters
- 2005
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Ingår i: Acta Orthop Suppl. - 1745-3690. ; 76:315, s. 3-82
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To evaluate the outcome of different types of polyethylene, bone cements and one design of uncemented fixation with porous and ceramic coating using radiostereometry, bone densitometry, conventional radiography and clinical parameters. MATERIALS AND METHODS: Study I: 201 patients were extracted from 5 prospective randomised studies to evaluate femoral head penetration at two years with radiostereometry in four basic designs, cemented Lubinus and Reflection cups, uncemented Trilogy and Reflection cups. Studies II and III: 60 patients (61 hips) were randomised to receive either highly cross-linked or conventional all PE cups. 32 patients with bilateral arthrosis received hybrid THA with highly cross-linked PE on one side and conventional on the contra lateral side. Femoral head penetration and the migration of the cups were evaluated with radiostereometry in the supine and standing positions. DEXA and conventional radiography were used to evaluate the bone mineral density and radiolucencies around the cemented acetabular component. Studies IV and V: 90 patients (97 and 96 hips respectively) were stratified depended on age, gender, diagnosis and preoperative BMD to create 3 main groups of socket fixation. In the first group fluoride containing cement was used, in the second group Palacos cum Gentamicin and in the third hybrid THA with porous coated HA/TCP cup. In the hybrid group the fixation of the femoral component was again randomised to either of the two cements. The results on femoral and acetabular sides are presented separately in studies IV and V, respectively. RESULTS: Study I: Cups with polyethylene sterilized in EtO had almost twice the proximal and 3D penetration rates compared with gamma-sterilized polyethylene. Regression analysis showed that the type of sterilization, age and weight was the most important factors affecting the penetration rate. Studies II and III: In the cemented study the proximal penetration was lower in the study group independent of position at 3 years, while in the hybrid study the penetration was lower in the study group only in the supine position at 2 years. The migration of the cup did not differ between the plastics in both studies. At 2 years the periprosthetic radiolucency and BMD did not differ significantly between the 2 types of PE used in the cemented study. Study IV: The subsidence of the stem did not differ between the groups, but the periprosthetic BMD decreased more in fluoride cement group at 2 years. Conventional radiography revealed higher progression of radiolucent lines in the Palacos group, but only in one region. Study V: The proximal migration of the cup was almost similar in all three groups. The three dimensional migration was increased in patients with osteoporosis. Postoperative radiolucent lines tended to disappear with use of porous coating covered with HA/TCP. CONCLUSIONS: Study I: EtO sterilized polyethylene increased the femoral head penetration. Age and weight were also important predictors of the penetration rate. Studies II and III: The highly cross-linked polyethylene decreased the penetration rate mainly after one year probably reflecting less wear. The different mechanical properties of the two types of PE studied did not affect the early fixation of the cemented cup. Study IV: There were no obvious advantage of addition of fluoride to acrylic bone cement when used to fixate the femoral component. Study V: Use of fluoride containing cement or uncemented fixation did not improve the early stability of the socket compared to Palacos with Gentamicin.
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| 10. |
- Digas, Georgios, 1963
(författare)
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New polymer materials in total hip arthroplasty. Evaluation with radiostereometry, bone densitometry, radiography and clinical parameters
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aims: To evaluate the outcome of different types of polyethylene, bone cements and one design of uncemented fixation with porous and ceramic coating using radiostereometry, bone densitometry, conventional radiography and clinical parameters.Materials and methods: Study 1: 201 patients were extracted from 5 prospective randomised studies to evaluate femoral head penetration at two years with radiostereometry in four basic designs, cemented Lubinus and Reflection cups, uncemented Trilogy and Reflection cups. Studies II and III. 60 patients (61 hips) were randomised to receive either highly cross-linked or conventional all PE cups. 32 patients with bilateral arthrosis received hybrid THA with highly cross-linked PE on one side and conventional on the contra lateral side. Femoral head penetration and the migration of the cups were evaluated with radiostereometry in the supine and standing positions. DEXA and conventional radiography were used to evaluate the bone mineral density and radiolucencies around the cemented acetabular component. Studies IV and V: 90 patients (97 and 96 hips respectively) were stratified depended on age, gender, diagnosis and preoperative BMD to create 3 main groups of socket fixation. In the first group fluoride containing cement was used, in the second group Palacos cum Gentamicin and in the third hybrid THA with porous coated HA/TCP cup. In the hybrid group the fixation of the femoral component was again randomised to either of the two cements. The results on femoral and acetabular sides are presented separately in studies IV and V, respectively.Results: Study I: Cups with polyethylene sterilized in EtO had almost twice the proximal and 3D penetration rates compared with gamma-sterilized polyethylene. Regression analysis showed that the type of sterilization, age and weight was the most important factors affecting the penetration rate. Studies II and III: In the cemented study the proximal penetration was lower in the study group independent of position at 3 years, while in the hybrid study the penetration was lower in the study group only in the supine position at 2 years. The migration of the cup did not differ between the plastics in both studies. At 2 years the periprosthetic radiolucency and BMD did not differ significantly between the 2 types of PE used in the cemented study. Study IV: The subsidence of the stem did not differ between the groups, but the periprosthetic BMD decreased more in fluoride cement group at 2 years. Conventional radiography revealed higher progression of radiolucent lines in the Palacos group, but only in one region. Study V: The proximal migration of the cup was almost similar in all three groups. The three dimensional migration was increased in patients with osteoporosis. Postoperative radiolucent lines tended to disappear with use of porous coating covered with HA/TCP.Conclusions: Study I: EtO sterilized polyethylene increased the femoral head penetration. Age and weight were also important predictors of the penetration rate. Studies II and III. The highly cross-linked polyethylene decreased the penetration rate mainly after one year probably reflecting less wear. The different mechanical properties of the two types of PE studied did not affect the early fixation of the cemented cup. Study IV: There were no obvious advantage of addition of fluoride to acrylic bone cement when used to fixate the femoral component. Study V: Use of fluoride containing cement or uncemented fixation did not improve the early stability of the socket compared to Palacos with Gentamicin.
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| 11. |
- Digas, Georgios, 1963, et al.
(författare)
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The Otto Aufranc Award. Highly cross-linked polyethylene in total hip arthroplasty: randomized evaluation of penetration rate in cemented and uncemented sockets using radiostereometric analysis
- 2004
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Ingår i: Clin Orthop Relat Res. - 0009-921X. ; :429, s. 6-16
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Tidskriftsartikel (refereegranskat)abstract
- The annual wear rate in polyethylene articulations should be 0.1 mm or less to avoid future osteolysis. Highly cross-linked polyethylene shows an 80 to 90% wear reduction in hip simulator testing, but the clinical documentation of this new polyethylene is still inadequate. We evaluated the highly cross-linked polyethylene in two prospective randomized clinical studies. Thirty-two patients (12 men, 20 women; 64 hips) with a median age of 48 years (range, 29-70 years) with bilateral primary or secondary arthrosis of the hip had hybrid total hip arthroplasty with liners made of highly cross-linked polyethylene on one side and conventional polyethylene on the other. Twenty-seven patients in this study have passed 2 years followup. A further group, comprised of 60 patients (61 hips) with a median age of 55 years (range, 35-70 years), was randomized to receive either highly cross-linked polyethylene or conventional cemented all-polyethylene of the same design. Forty-nine of these 60 patients have been observed for 3 years. In both studies all patients received Spectron stems with 28-mm Co-Cr heads. Radiostereometric examinations with the patient supine or standing were done at regular intervals. Wear was measured in the supine position from the first postoperative week, whereas standing examinations were initiated 3 months after the operation. The penetration rate almost was identical in the study and control groups at 6 months after the operation. Thereafter, the penetration rate leveled out in the two groups with highly cross-linked polyethylene. At 2 years the highly cross-linked polyethylene liner showed 62% lower proximal penetration and 31% lower total (three-dimensional) penetration when the patients were examined in supine position. The highly crosslinked all-polyethylene cemented cups showed lower proximal penetration in both positions. The better wear performance of highly cross-linked polyethylene could increase the implant longevity. Longer followup is needed to evaluate if this new material is associated with less occurrence of osteolysis.
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| 12. |
- Johanson, Per-Erik, et al.
(författare)
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Highly Crosslinked Polyethylene Does Not Reduce Aseptic Loosening in Cemented THA 10-year Findings of a Randomized Study.
- 2012
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Ingår i: Clinical orthopaedics and related research. - : Ovid Technologies (Wolters Kluwer Health). - 1528-1132 .- 0009-921X. ; 470:11, s. 3083-93
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Tidskriftsartikel (refereegranskat)abstract
- Polyethylene (PE) wear particles are believed to cause aseptic loosening and thereby impair function in hip arthroplasty. Highly crosslinked polyethylene (XLPE) has low short- and medium-term wear rates. However, the long-term wear characteristics are unknown and it is unclear whether reduced wear particle burden improves function and survival of cemented hip arthroplasty.
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| 13. |
- Karladani, Abbas, 1954, et al.
(författare)
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Ankle arthrodesis using dowel bone graft and cancellous-bone screws: a mechanical study in cadavers
- 2004
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Ingår i: Acta Orthop Scand. - 0001-6470. ; 75:4, s. 471-6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: There are numerous techniques for ankle arthrodesis. MATERIAL AND METHODS: We studied the stability of an ankle arthrodesis with the use of two cross-screws combined with dowel graft technique in 14 fresh-frozen ankles from amputees. The arthrodesis was performed by a dowel graft technique, in the coronal plane in 7 specimens (group 1) and in the diagonal plane in the remaining 7 (group 2). Allocation into the two groups took place after normalization according to the bone mineral content of the specimens. All ankles were fixed with two 6.5-mm diameter cancellous-bone screws, with the ankle in neutral position. Tibiotalar motion was measured during 5 Nm torque loading in plantar flexion-dorsiflexion, abduction-adduction and eversion-inversion planes of the ankle joint. Two testing sequences were performed and the mean value of both tests in each direction was used for the analysis. RESULTS: In all 3 planes, the torque applied caused more motion with the dowel graft in the coronal plane (group 1) than with the graft in the diagonal plane (group 2). The differences between the two groups were significant for abduction-adduction and eversion-inversion planes. Statistical analysis of differences between the first and second test showed significantly greater stiffness in group 2 than in group 1 in plantar flexion-dorsiflexion torque. INTERPRETATION: The placement of a dowel graft in the diagonal plane in comparison to the coronal plane significantly increased the initial stability of an ankle arthrodesis.
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| 14. |
- Olofsson, Kent, 1956, et al.
(författare)
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Influence of design variations on early migration of a cemented stem in THA
- 2006
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Ingår i: Clin Orthop Relat Res. - 0009-921X. ; 448, s. 67-72
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Tidskriftsartikel (refereegranskat)abstract
- The clinical results of using different cemented stems in total hip arthroplasty may vary because of shape, surface finish, and choice of metal alloy. Less is known about the influence of size and offset using one and the same design. Data from 140 patients (140 hips) of a cohort constituting 197 patients (231 hips) implanted with cemented Spectron Primary stems were extracted from patients studied in four randomized studies primarily designed for other purposes. Stem size (1, 2, 3, or larger), normal/extra offset, neck length and true offset (horizontal length between the stem and head center of the inserted modular implant) were recorded in millimeters. The radiographic appearance of the cementing was graded on the immediate postoperative radiograph according to Barrack. The patients were examined with radiostereometric analysis of stem migration for a 2-year followup period. Stem Size 1 (the smallest) showed an insignificant increase in subsidence compared with the bigger sizes. Using stepwise linear regression analysis, the quality of the cementing (Barrack C2) was the only parameter that had any certain influence of the subsidence at 2 years. Stem size 2 tended to show minimum valgus alignment and sizes 1 and 3 and bigger showed minimum varus tilting. Our findings suggest that placement of the stem with the tip against the posterior cortex (C2) and stem size influence the primary fixation in different ways. This effect is small, however, indicating that further confirmation with longer followup is necessary. LEVEL OF EVIDENCE: Therapeutic Level II-1 (prospective cohort study). See the Guidelines for Authors for a complete description of levels of evidence.
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| 15. |
- Rolfson, Ola, 1973, et al.
(författare)
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One-stage bilateral total hip replacement is cost-saving
- 2014
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Ingår i: Orthopedic & Muscular System: Current Research. - : OMICS Publishing Group. - 2161-0533. ; 12:3 (4)
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Tidskriftsartikel (refereegranskat)abstract
- Many patients suffer from bilateral hip disease. For these patients two-stage bilateral total hip replacement (THR) is more common than a one-stage procedure because of fear of complications associated with one-stage surgery. However, many studies are in favour of one-stage bilateral THR in healthy and young patients. We investigated costs, complications and patient-reported outcome related to one-stage bilateral THR. Unilateral THR was used as a reference. Thirty-two patients with one-stage bilateral THR were prospectively followed for six years (bilateral group). A matched reference population of 32 patients with unilateral THR was assembled (unilateral group). Medical records, individual data from the Swedish Hip Arthroplasty Register, the Swedish Social Insurance Administration and local data on cost per patient were used for the analyses. For non-retired patients, the duration and costs for sick leave during the first postoperative year were similar in both groups. The rate of complications and their severity were similar in both groups. Using cost data from this study in a theoretical model, comparing one- and two-staged procedures showed a 24% reduction in hospital and sick-leave costs in favour of the one-stage procedure. Our results indicate that the one-stage procedure is cost-saving compared to two-stage procedures for patients with indication for bilateral THR
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