Acta orthopaedica Scandinavica. Supplementum最新文献

The Swedish National Total Hip Arthroplasty Register contains more than 200,000 primary and secondary hip replacements. The failure end-point definition is revision. The aim of this thesis was to validate the results presented by the register and to study the outcome of hip replacement surgery in Sweden. The hypothesis was firstly that the number of failure reported to the Swedish THA register are valid and secondly that adding clinical and radiographic failure criteria will dramatically decrease the survival rate for THR implants. The study consisted of three parts with 2-10 years follow-up of patients with total hip replacements (THR). In part I, three general health questionnaires (Nottingham Health Profile, SF-36, EuroQol) and two disease-specific instruments (WOMAC, Harris Hip Score) were tested for validity and reliability (n = 62). The results showed the disease specific questionnaires are at least as valid and reliable as the general instruments are. In part II, all THRs reported to the Swedish THA register 1986 to 1994 (84,884 primary and 10,176 revision hip replacements) were compared with the data from the Discharge register and the Cause of Death register in Sweden. 2,604 patients were randomly selected from the Discharge register to determine if they had undergone any revision surgery. The study showed that the Swedish THA register covers 94% of the revisions actually performed in Sweden and the results did not differ significantly from the data in the Discharge register and the results reported by the patients. In part III, 1,056 patients from the selected cohort were studied further concerning general health and disease-specific health, using the Nottingham Health Profile, SF-36 and WOMAC. An age and gender matched subcohort of 344 patients were then examined clinically, using the Harris Hip Score, and radiographically. The clinical and radiographic failure rates were in several tests as high as the revision rates documented in the Swedish THA register. The clinical results were, however, dependent on demographics, the definition of clinical failure and the scoring system used. The results presented by the register with revision as failure end-point give an exact but limited information about the quality of hip replacement surgery in Sweden.

In allowing compression along the femoral shaft (uniaxial dynamization) and optional compression along the femoral neck (biaxial dynamization), the Medoff sliding plate (MSP) represents a new principle in the fixation of trochanteric hip fractures. The Twin hook with 2 apical hooks was designed as an alternative to the lag screw. In 3 prospective consecutive case series and 1 prospective randomized study together comprising 342 trochanteric fractures, these alternative techniques were investigated. 3 postoperative fixation failures occurred in the unstable intertrochanteric fractures treated with biaxial dynamization with the MSP (n = 194), and 5 in those treated with the sliding hip screw (n = 62) (p = 0.04). A mean femoral shortening of 15 mm with the MSP and 11 mm with the sliding hip screw was found (p = 0.03). More medialization of the femoral shaft occurred with the sliding hip screw (26%) than with the MSP (12%) in patients with marked femoral shortening (p = 0.03). 3 postoperative fixation failures occurred in subtrochanteric fractures treated with uniaxial dynamization (n = 29) and 2 in those treated with biaxial dynamization (n = 19). Medialization of the femoral shaft occurred in 9 of the 19 biaxially dynamized fractures. The Twin hook was used in 50 patients and appeared to provide similar fixation stability as the lag screw. Biomechanical tests confirmed improved stress transmission over the fracture area with the MSP compared to the sliding hip screw in intertrochanteric fractures, and similar fixation stability with the MSP and the Intramedullary Hip Screw in subtrochanteric fractures. In axial and torsional loading, the Twin hook demonstrated gradually increasing resistance to migration. With the lag screw, the peak load was higher, but after migration with failure of the support by the threads, the loads were similar. Biaxial dynamization with the MSP appears to control fracture impaction effectively and minimizes the rate of postoperative fixation failure in intertrochanteric fractures. In subtrochanteric fractures, uniaxial dynamization prevents medialization of the femoral shaft and is therefore preferred to biaxial dynamization. The Twin hook appears to provide adequate fixation stability, and with potential for simplified intraoperative handling and reduced dissection, the Twin hook may pose advantages compared to the lag screw.

Initiated and motivated by clinical and scientific problems such as age-related bone fracture, prosthetic loosening, bone remodeling, and degenerative bone diseases, much significant research on the properties of trabecular bone has been carried out over the last two decades. This work has mainly focused on the central vertebral trabecular bone, while little is known about age-related changes in the properties of human peripheral (tibial) trabecular bone. Knowledge of the properties of peripheral (tibial) trabecular bone is of major importance for the understanding of degenerative diseases such as osteoarthrosis and osteoporosis, and for the design, fixation and durability of total joint prosthesis. The specific aims of the present studies were: 1) to investigate normal age-related variations in the mechanical, physical/compositional, and structural properties of human tibial trabecular bone; and 2) to investigate the age-related and osteoarthrosis-related changes in the mechanical properties of the human tibial cartilage-bone complex; and 3) to evaluate mutual associations among various properties. Normal specimens from human autopsy proximal tibiae were used for investigation of age variations in the properties of trabecular bone and the cartilage-bone complex, and osteoarthrotic specimens were used for the investigation of changes in the mechanical properties of the cartilage-bone complex induced by this disease process. The mechanical properties and physical/compositional properties of trabecular bone were quantified by means of standard techniques, and trabecular bone structure was quantified by means of unbiased three-dimensional methods. The present study demonstrated that the mechanical properties, such as Young's modulus, ultimate stress, ultimate strain and failure energy, and the densities, such as apparent, apparent ash and collagen densities of human tibial trabecular bone have significant relationships with age. Tissue density and mineral concentration remain constant throughout life. Trabecular bone is tougher in the younger age, i.e. fracture requires more energy. Collagen density was the single best predictor of failure energy, and collagen concentration was the only predictor of ultimate strain. The decrease in mechanical properties of trabecular bone mainly is a consequence of the loss of trabecular bone substance. This study showed that the degree of anisotropy (preferential orientation of trabeculae), mean marrow space volume, and bone surface-to-volume ratio increased significantly with age. Bone volume fraction, mean trabecular volume, and bone surface density decreased significantly with age. Connectivity did not have a general relationship with age, yet a trend exists. Age-related changes in the microstructural properties had the same trends for both medial and lateral condyles of the tibia. The observed increase of anisotropy may be interpreted as the consequence of structural adaptation secondary to age-induced bo

Unlabelled: Synovial sarcoma accounts for 5-10% of all soft tissue sarcomas. More than 90% are found in the extremities or trunk wall. Characteristic for synovial sarcoma is the translocation t(X;18) (p11.2;q11.2). Cloning of the breakpoints of this translocation revealed fusion of two novel genes, SYT and SSX. The SYT gene, located on chromosome 18, is fused with one of three closely related genes; SSX1, SSX2 or SSX4 located on the X chromosome. The long term survival rates have continuously improved and have at best been reported to around 50%. However, since almost no population based studies on synovial sarcoma have been reported, these improvements may be due to differences in patient selection due to a changes in referral practice. This project was based on a consecutive series of synovial sarcoma patients from the Scandinavian Sarcoma Group Register acquired during a 9-year period. Only surgically treated patients without metastases at diagnosis were included in the prognostic analyses. The tumors were defined clinically, histopathologically, molecular and cytogenetically and these features were related to clinical course.

Epidemiology: 34 of 104 patients developed metastases. The overall 5 and 7 years survival rates were 0.76 (95% CI 0.66-0.83) and 0.69 (0.58-0.78), respectively. Large tumor size and amputation were significantly associated with impaired metastasis free survival. In addition, patients with local recurrence had a higher risk for metastases following the local event.

Histology: All were high grade lesions, 74 Grade III and 30 IV. Kaplan-Meier estimates of metastasis-free survival at 5 years were 83% (95% CI 72-92%) for patients with Grade III tumors versus 31% (95% CI 13-51%) for Grade IV. Histologic grading conveyed more prognostic information than any single histologic factor. Immunostaining with anti-Ki-67 antibodies (MIB1) and p53 based on formalin-fixed paraffin-embedded material from 86 patients revealed that MIB-1 > or = 10% was associated with poorer metastasis-free survival but p53 was not.

Genetics: Type of fusion transcripts (SYT-SSX1 or SYT-SSX2) and Ki-67 were assessed in fresh frozen tissue from 33 patients. The 5-year metastasis-free survival for patients with SYT-SSX1 was 42% versus 89% for those with SYT-SSX2. The hazard ratio for metastasis associated with the SYT-SSX1 fusion transcripts was 7 (95% CI 1.5-36, log-rank p = 0.004). There was a significant association between SYT-SSX1 and high tumor proliferation rate. Comparative Genomic Hybridization revealed DNA sequence copy number changes in 35 of 69 tumor specimens. The frequency of aberrations/tumor were higher in monophasic tumors than in biphasic. Gains of chromosome 8 were associated with large tumors (> 5 cm). There was no obvious association between secondary aberrations and clinical outcome.

Conclusions: Large tumor size, local recurren

The results of primary hip replacements are good. However, dealing with a loose prosthesis has been problematic, especially when major bone deficiencies are encountered. These problems appear to have been solved by the introduction of the Slooff-Ling method of using morselized and impacted allograft chips. The clinical results are excellent in the hands of the innovators. However, it remains confusing that a thick layer of dead, broken, immunogenic tissue taken from another individual does not resorb and collapse during remodeling. Still harder to understand is the impression, as judged by radiography, that this thick layer seems to incorporate and remodel up to a distance of perhaps 10 mm or more from the host bone, whereas the ingrowth distance into a non-morselized graft is limited to a few mms. To clarify the biological basis of the morselized and impacted grafts better, the present study was stated. Three hypotheses were initially proposed to explain the good clinical results: 1. Morselization releases growth factors present in the graft (osteoinduction). 2. Impaction makes it easier for the ingrowing bone to climb up into the graft (osteoconduction). 3. The compliance or elasticity of the graft allows the load to produce deformations that stimulate bone formation (mechanical load). In the first studies, bone chambers were implanted in rats and the distance of new bone ingrowth into a graft in the chamber was measured. In Paper I, a morselized graft was deproteinized by slow heating under high pressure. Ingrowing bone did not reach so far into the deproteinized graft as into a non-treated one. We concluded that the proteins present in the graft partly determine how far ingrowing new bone will extend into a graft. In Paper II, a cancellous graft was impacted so that the bone volume fraction of the graft rose from 35% in the unimpacted to 65%. The impacted grafts were compared to unimpacted ones and it was shown that impaction reduced the ingrowth of new bone into a graft in the chamber at six weeks. In Paper III, this somewhat unexpected finding was further studied. Syngeneic and allogeneic grafts showed a reduced ingrowth distance at six weeks when impacted, compared to unipacted controls. However, the reduction was not found when the time for ingrowth was extended to 12 weeks, indicating a possible catch-up phenomenon. Moreover, an exogenously applied growth factor, osteogenic protein-1, was found to have increased the ingrowth distance of new bone into impacted grafts at six weeks. In Paper IV, a rabbit knee prosthesis was developed to study the effect of a mechanical load on the remodeling of a morselized and impacted graft. All rabbits had their tibial marrow cavity cleansed of cancellous bone, which was replaced by a morselized and impacted bone graft. Six rabbits received a complete tibial prosthesis with a tibial load-bearing tray and a stem transferring the load to the impacted graft with each step made by the rabbit. Another s

Although cementless knee arthroplasty is a commonly performed procedure, to date very little was known about the process of osseointegration of knee arthroplasty components. Using a knee prosthesis that was specially designed for the sheep stifle joint, this process of osseointegration could be studied in vivo, together with its effects on clinical and functional performance, its influence on mechanical fixation, and its influence on component stability or migration over time. Additionally, the osseointegration capacity of a newly developed cast mesh porous coating could be examined. The rationale for this newly developed coating was to provide a surface texture with theoretically superior osseointegration capacity, by offering a larger and better controlled pore size, with higher ingrowth area compared to conventional bead type coatings. In summary, the conclusions that are drawn from this work are the following: 1. The degree of osseointegration of knee arthroplasty components is not correlated with clinical and functional performance. Knee arthroplasty components with fibrous integration can function as well as osseointegrated components at least during the first years after implantation. This explains the occasional reports in the literature of post mortem retrieved, well functioning knee arthroplasty components, with purely fibrous integration on histomorphometric analysis. 2. Fibrous integration of tibial knee arthroplasty components, however, leads to less mechanical fixation strength of these components. Osseointegrated components are much more strongly fixed to the underlying bone. This difference in mechanical fixation strength is detectable under physiologic loads. 3. Fibrous integration of tibial knee arthroplasty components leads to increased migration, becoming apparent after 1 year with radiostereometric analysis (RSA). Osseointegrated components are significantly more stable over time. 4. Fibrous integration is less desirable, since it leads to mechanically less rigidly fixed implants, and subsequently to migration over time. On the long-term, fibrous integration might therefore lead to loosening. 5. RSA is an effective tool to assess migration of knee arthroplasty components. The RSA migration of an uncemented component is also an indicator of its degree of osseointegration and its mechanical fixation strength, since RSA migration is correlated with these two parameters. RSA is therefore especially useful during the first postoperative years, since increased migration indicates fibrous integration and low mechanical fixation strength, suggesting an increased risk for subsequent loosening at a later stage. Patients with increased early component migration on RSA might therefore be advised to impose specific restrictions on their knee arthroplasty. 6. Osseointegration is not routinely achieved in conventional porous coated tibial knee arthroplasty components. The development of a theoretically superior cast mesh coating did n