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  • 1. Callary, Stuart A.
    et al.
    Campbell, David G.
    Mercer, Graham
    Nilsson, Kjell G.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Field, John R.
    Wear of a 5 Megarad Cross-linked Polyethylene Liner: A 6-year RSA Study2013Inngår i: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, Vol. 471, nr 7, s. 2238-2244Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One cross-linked polyethylene (XLPE) liner is manufactured using a lower dose of radiation, 5 Mrad, which may result in less cross-linking. The reported in vivo wear rate of this XLPE liner in patients undergoing THA has varied, and has included some patients in each reported cohort who had greater than 0.1 mm/year of wear, which is an historical threshold for osteolysis. Previous studies have measured wear on plain radiographs, an approach that has limited sensitivity. We therefore measured the amount and direction of wear at 6 years using Radiostereometric analysis (RSA) in patients who had THAs that included a cross-linked polyethylene liner manufactured using 5 Mrad radiation. We prospectively reviewed wear in 30 patients who underwent primary THAs with the same design of cross-linked acetabular liner and a 28-mm articulation. Tantalum markers were inserted during surgery and all patients had RSA radiographic examinations at 1 week, 6 months, 1, 2, and 6 years postoperatively. The mean proximal, two-dimensional (2-D) and three-dimensional (3-D) wear rates calculated between 1 year and 6 years were 0.014, 0.014, and 0.018 mm/per year, respectively. The direction of the head penetration recorded between 1 week and 6 years was in a proximal direction for all patients, proximolateral for 16 of 24 patients, and proximomedial for eight of 24 patients. The proximal, 2-D and 3-D wear of a XLPE liner produced using 5 Mrad of radiation was low but measurable by RSA after 6 years. No patients had proximal 2-D or 3-D wear rates exceeding 0.1 mm/year. Further followup is needed to evaluate the effect of XLPE wear particles on the development of long-term osteolysis.

  • 2.
    Campbell, David
    et al.
    Orthopaedic Unit, Repatriation General Hospital, Daws Road, Daw Park, SA 5041 Australia.
    Mercer, Graham
    Orthopaedic Unit, Repatriation General Hospital, Daws Road, Daw Park, SA 5041 Australia.
    Nilsson, Kjell Gunnar
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Callary, Stuart A.
    Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA Australia .
    Case report: Cementless stem stabilization after intraoperative fracture: A radiostereometric analysis2010Inngår i: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, Vol. 468, nr 3, s. 898-901Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the case of a patient with intraoperative femoral fracture during THA, which was repaired using cerclage fixation and insertion of an hydroxyapatite-coated cementless stem. The patient was evaluated postoperatively using radiostereometry during a 2-year course, and despite a large amount of subsidence and rotation, stabilization occurred and was maintained by 6 months. By evaluating the pattern of stem migration after intraoperative fracture, this case shows, even in the presence of instability, a successful clinical outcome can be achieved using an hydroxyapatite-coated cementless stem.

  • 3.
    Dahl, Morten
    et al.
    Institute of Sports Medicine, Department 8, Bispebjerg Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
    Hansen, Philip
    Institute of Sports Medicine, Department 8, Bispebjerg Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
    Stål, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Edmundsson, David
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Magnusson, S. Peter
    Institute of Sports Medicine, Department 8, Bispebjerg Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
    Stiffness and thickness of Fascia do not explain chronic exertional compartment syndrome2011Inngår i: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, Vol. 469, nr 12, s. 3495-3500Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background   Chronic exertional compartment syndrome is diagnosed based on symptoms and elevated intramuscular pressure and often is treated with fasciotomy. However, what contributes to the increased intramuscular pressure remains unknown.

    Questions/purposes   We investigated whether the stiffness or thickness of the muscle fascia could help explain the raised intramuscular pressure and thus the associated chronic compartment syndrome symptoms.

    Patients and Methods   We performed plain radiography, bone scan, and intramuscular pressure measurement to diagnose chronic compartment syndrome and to exclude other disorders. Anterior tibialis muscle fascial biopsy specimens from six healthy individuals, 11 patients with chronic compartment syndrome, and 10 patients with diabetes mellitus and chronic compartment syndrome were obtained. Weight-normalized fascial stiffness was assessed mechanically in a microtensile machine, and fascial thickness was analyzed microscopically.

    Results   Mean fascial stiffness did not differ between healthy individuals (0.120 N/mg/mm; SD, 0.77 N/mg/mm), patients with chronic compartment syndrome (0.070 N/mg/mm; SD, 0.052 N/mg/mm), and patients with chronic compartment syndrome and diabetes (0.097 N/mg/mm; SD, 0.073 N/mg/mm). Similarly, no differences in fascial thickness were present. There was a negative correlation between fascial stiffness and intramuscular pressure in the patients with chronic compartment syndrome and diabetes.

    Conclusions   The lack of difference in fascial thickness and stiffness in patients with chronic compartment syndrome and patients with chronic compartment syndrome and diabetes compared with healthy individuals suggests structural and mechanical properties are unlikely to explain chronic compartment syndrome. To prevent chronic exertional compartment syndrome, it is necessary to address aspects other than the muscle fascia.

  • 4.
    Haapala, Jussi
    et al.
    Department of Surgery, Kuopio University Hospital, Kuopio, Finland; Department of Rehabilitation Clinic, Kuopio University Hospital, Kuopio, Finland.
    Arokoski, Jari
    Department of Rehabilitation Clinic, Kuopio University Hospital, Kuopio, Finland.
    Hyttinen, Mika
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Tammi, Markku
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Kovanen, Vuokko
    Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
    Helminen, Heikki
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Kiviranta, Ilkka
    Department of Surgery, Jyväskylä Central Hospital, Jyväskylä, Finland.
    Remobilization does not fully restore immobilization induced articular cartilage atrophy.1999Inngår i: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, nr 362, s. 218-229, artikkel-id 10335301Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The recovery of articular cartilage from immobilization induced atrophy was studied. The right hind limbs of 29-week-old beagle dogs were immobilized for 11 weeks and then remobilized for 50 weeks. Cartilage from the immobilized knee was compared with tissue from age matched control animals. After the immobilization period, uncalcified articular cartilage glycosaminoglycan concentration was reduced by 20% to 23%, the reduction being largest (44%) in the superficial zone. The collagen fibril network showed no significant changes, but the amount of collagen crosslinks was reduced (13.5%) during immobilization. After remobilization, glycosaminoglycan concentration was restored at most sites, except for in the upper parts of uncalcified cartilage in the medial femoral and tibial condyles (9% to 17% less glycosaminoglycans than in controls). The incorporation of 35SO4 was not changed, and remobilization also did not alter the birefringence of collagen fibrils. Remobilization restored the proportion of collagen crosslinks to the control level. The changes induced by joint unloading were reversible at most sites investigated, but full restoration of articular cartilage glycosaminoglycan concentration was not obtained in all sites, even after remobilization for 50 weeks. This suggests that lengthy immobilization of a joint can cause long lasting articular cartilage proteoglycan alterations at the same time as collagen organization remains largely unchanged. Because proteoglycans exert strong influence on the biomechanical properties of cartilage, lengthy immobilization may jeopardize the well being of articular cartilage.

  • 5.
    Henricson, Anders
    et al.
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap.
    Dalén, Tore
    Nilsson, Kjell G
    Mobile bearings do not improve fixation in cemented total knee arthroplasty2006Inngår i: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, Vol. 448, s. 114-121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mobile bearings were introduced to improve wear and knee kinematics. By uncoupling the forces generated at the articulation from the implant-bone interface this would, theoretically, also improve the fixation of the implant to bone. We did this study to evaluate whether mobile bearings improve the fixation of the tibial component to bone. Fifty-two consecutive knees in 47 patients (average age, 72 years; range, 62-84 years) with primary osteoarthrosis were randomized into two groups to receive a cemented total knee arthroplasty with either a fixed-bearing or mobile-bearing tibial component. The quality of fixation was analyzed with radiostereometric analysis for up to 2 years. Mobile bearings did not improve fixation. Both magnitudes and directions of component rotations were similar, and the number of implants with continuous migration was almost identical. Both implant types had a combination of subsidence and lift-off, but where the mobile bearing implants displayed more of subsidence, the fixed bearing knees showed more lift-off. It might be that the somewhat stiffer cobalt-chromium baseplate or the different joint conformity used in the mobile-bearing knees counteracts any potential effects of the mobile bearing.

  • 6.
    Nilsson, Kjell G
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Henricson, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Norgren, Bo
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Dalén, Tore
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Uncemented HA-coated implant is the optimum for the TKA in the young patient2006Inngår i: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, Vol. 448, s. 129-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fixation of the tibial component in total knee arthroplasty in younger patients remains controversial. We evaluate the results of three different types of fixation of the Profix total knee arthroplasty in a randomized controlled trial of 97 consecutive knees (85 patients) with osteoarthrosis or inflammatory arthritis with 2-year followup of all patients. We randomized patients to three different types of fixation of the tibial component: cemented, uncemented (HA coated) with screws, or uncemented (HA coated) without screws. We performed clinical evaluations and radiostereometric analysis at 6 weeks, and 3, 6, 12 and 24 months postoperatively. The knees in the uncemented groups migrated more than those in the cemented group during the first 3 months, but at 2 years we observed no differences. The uncemented implants displayed all migration within the first 3 months. The cemented implants did not stabilize but had continuously increasing migration during the followup. Cementless implants without screws did not migrate more than implants with screws and displayed similar pattern of migration, indicating screws do not improve fixation. Uncemented fixation using hydroxyapatite-coated implants without screws seems to be the best solution for the younger patient.

  • 7.
    Röhrl, Stephan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Li, Ming G
    Perth Orthopaedic Institute, University of Western Australia.
    Pedersen, E
    Department of Orthopaedic Surgery, Sundsvall Hospital.
    Ullmark, G
    Department of Orthopaedic Surgery, Gävle Hospital.
    Nivbrant, B
    Perth Orthopaedic Institute, University of Western Australia.
    Migration pattern of a short femoral neck preserving stem2006Inngår i: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, Vol. 448, nr July, s. 73-78Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AB The CFP stem represents a short collared neck-retaining stem with very proximal metaphyseal anchoring along the calcar combined with up-to-date metallurgy. Despite theoretical advantages, the stability and clinical outcome are unknown. We prospectively measured the migration pattern of this new stem and cup. Twenty-six patients (26 hips) with a mean age of 54 years (range, 40-66 years) underwent THA and were followed for 2 years with radiostereometry, radiographs, and clinical scores. The stem showed some early retroversion (mean, SEM 0.6[degrees], 0.3), but stabilized before 1 year. Subsidence (0.05 mm, 0.06) and varus-valgus tilting (0.03[degrees], 0.01) were low. We observed no bone loss in the calcar region. Factors related to patients, implant design, and implantation did not predict migration patterns. The two-dimensional wear of the ceramic/conventional articulation was 0.09 mm at 2-24 months. The low migration of this short neck preserving stem suggests a favorable long-term outcome but longer followup is needed to substantiate this prediction. This design might become an alternative to standard stems and hip resurfacing. Level of Evidence: Therapeutic Level IV. See The Guidelines for Authors for a complete description of levels of evidence.

  • 8.
    Zhou, Zong-ke
    et al.
    University of Western Australia.
    Li, Ming G.
    University of Western Australia.
    Börlin, Niclas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wood, David J.
    University of Western Australia.
    Nivbrant, Bo
    University of Western Australia.
    No Increased Migration in Cups with Ceramic-on-Ceramic Bearing: An RSA Study2006Inngår i: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, nr 448, s. 39-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ceramic-on-ceramic hip replacements might stress the bone interface more than a metal-polyethylene because of material stiffness, microseparation, and sensitivity to impingement. To ascertain whether this potentially increased stress caused an increased cup migration we compared a ceramic-on-ceramic with a metal-on-polyethylene implant for cup migration. Sixty one patients (61 hips) undergoing THA for osteoarthritis were randomized to ceramic on ceramic (Ce/Ce) or cobalt-chromium on cross-linked polyethylene bearings (PE) in the same uncemented cup shell. Migrationwas followed with RSA. At 2 years we observed similar mean cup translations in the 3 directions (0.07–0.40 mm vs. 0.05–0.31 mm, Ce/Ce vs. PE), as well as similar rotations around the 3 axes (0.31–0.92° vs. 0.57–1.40°). WOMAC and SF-36 scores were also similar and no radiolucent lines or osteolysis found. The large migration seen in some cups in both implant groups will require close monitoring to ascertain the reasons. Mean proximal wear of the polyethylene liners measured 0.016 mm between 2 and 24 months. Our data suggest there is no increased cup migration in the ceramic-on-ceramic implant compared with the metal-on-polyethylene, and they seem an equally safe choice. However, the low wear measured with the more versatile and less expensive cross-linked polyethylene makes it a strong contender. Levels of Evidence: Therapeutic Level I. See the Guidelinesfor Authors for a complete description of levels of evidence.

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