[Functional outcomes and return to sports, work, and daily activities after revision UKA compared to primary UKA and TKA]. / Funktionelle Ergebnisse und Wiederaufnahme von Sport, Arbeit und Alltagsaktivitäten nach Revision eines Monoschlittens im Vergleich zur Primärimplantation eines Mono- und Doppelschlittens.

BACKGROUND: Unicompartmental knee arthroplasty (UKA), in addition to total knee arthroplasty (TKA), has been shown to be effective in the surgical treatment of knee osteoarthritis with appropriate patient selection. In clinical studies, it has demonstrated superior functional results with lower complication rates. In clinical practice, these advantages must be weighed against the disadvantage of an increased revision rate, especially in younger patients with sports and work activities. OBJECTIVES: The aim of this study was to compare the functional outcome as well as the time to return to daily activities, work, and sports after revision of UKA to TKA with those of primary UKA and primary TKA using a matched-pair analysis. MATERIALS AND METHODS: The study was based on a matched-pair analysis at two defined time points, always comparing 28 patients who underwent either revision of a UKA to a TKA, primary UKA, or primary TKA. Patients completed the Oxford Knee Score, UCLA score, Knee Society score, and WOMAC score during standardized follow-up. In addition, postoperative patient satisfaction and return to activities of daily living, work, and sports were recorded in a standardized manner, and a clinical examination was performed. RESULTS: The four functional scores studied showed a common trend in favor of UKA, followed by primary TKA and revision TKA. The differences between converted UKA and primary TKA were not significant. However, at 3.2 years after the last surgery, the results of the converted UKA were significantly lower than those of the primary UKA. Return to work and sports tended to occur the earliest after UKA, followed by TKA and the revision group. All groups showed a tendency to engage in low-impact sports. CONCLUSION: The functional results of revised UKA were significantly inferior to those of primary UKA based on a 3-year follow-up. Return to work, sports, and activities of daily living tended to take longer after revision than after primary implantation of either a UKA or a TKA.

Insights into the Distribution Patterns of Foot and Ankle Tumours: Update on the Perspective of a University Tumour Institute.

The rarity of foot and ankle tumours, together with the numerous histological entities, presents a challenge in accumulating sufficient patients to draw reliable conclusions. Therefore, we decided to present an update of a retrospective analysis of their distribution patterns, comprising 536 cases of foot and ankle tumours presented to our tumour board between June 1997 and June 2023. Our aim was to provide a comprehensive overview of the prevalence and distribution patterns of benign and malignant bone and soft tissue tumours of the foot and ankle. A total of 277 tumours involved bone (51.7%). Of these, 242 (87.4%) were benign and 35 (12.6%) were malignant. In addition, 259 soft tissue tumours (48.3%) were found, of which 191 (73.7%) were benign and 68 (26.3%) were malignant. The most common benign bone tumours were simple bone cysts, enchondromas, osteochondromas, aneurysmal bone cysts, and lipomas of bone. Common benign soft tissue tumours included a tenosynovial giant cell tumour, haemangioma, plantar fibromatosis, schwannoma, and lipoma. The most common malignant soft tissue tumours were synovial sarcoma, malignant melanoma, and myxofibrosarcoma. In terms of anatomical location, the hindfoot was the most common site (28.7%), followed by the midfoot (25.9%), ankle (25.4%), and forefoot (20.0%). The distribution of benign entities often follows typical patterns, which may facilitate an early diagnosis even without biopsy (e.g., simple bone cyst, plantar fibromatosis). On the other hand, the distribution patterns of many rare or malignant entities are inconsistent. Individual soft tissue malignancies occur very sporadically, even over long periods of time and in specialized tumour centres. It is therefore important to recognise that any suspicious mass in the foot and ankle must be considered a possible malignancy until proven otherwise.

Patient reported outcomes of duodenum-preserving pancreatic head resection in chronic pancreatitis: high effectivity is impaired by prolonged non-surgical management.

BACKGROUND: Chronic pancreatitis (CP) causes suffering and socioeconomic burden. This study evaluated perioperative results and patient-reported outcomes (PRO) in CP patients treated with duodenum-preserving pancreatic head resection (DPPHR). METHODS: Data were analyzed of CP patients undergoing DPPHR between 01/2001-10/2014. PROs were measured using a specifically designed questionnaire and the EORTC QLQ-C30/PAN26. Associations between treatment variables and PROs were examined. RESULTS: Of 332 patients who received DPPHR, most (n = 251, 75.6%) underwent the Berne modification. Surgical morbidity was 21.5% (n = 71) and 90-day mortality 1.5% (n = 5). Median follow-up was 79.9 months, 5-year survival 90.5%, and 1.8% of patients developed pancreatic cancer. Of 283 patients alive, 178 (62.9%) returned questionnaires. Referral for surgery was self-initiated (38.0% of cases), by gastroenterologists (27.5%) and by general practitioners (21.1%). QoL improved in 78.7% of patients, remained stable in 12.1%, and worsened in 9.1%. Median Izbicki scores decreased from 90 to 5 points after surgery (p < 0.0001). Time from diagnosis to DPPHR was an independent, proportional predictor of a higher postoperative Izbicki score (p = 0.04). CONCLUSION: DPPHR is an effective, safe treatment for CP. A delay in surgery decreases surgical effectivity, hence CP patients should be referred to surgery early to ensure satisfactory outcomes.

Radiographic Evaluation of First Tarsometatarsal Joint Arthrodesis for Hallux Valgus Deformity: Does the Fusion of the First to the Second Metatarsal Base Reduce the Radiological Recurrence Rate?

BACKGROUND: Modified Lapidus arthrodesis (MLA) is a well-established treatment option for symptomatic hallux valgus deformity (HVD). However, recurrence of the deformity remains a concern. The goal of this study was to evaluate the effect of an additional intermetatarsal fusion on the radiographic recurrence rate after first tarsometatarsal (TMT-I) arthrodesis. METHODS: This is a retrospective evaluation of 56 feet that underwent TMT-I arthrodesis for moderate to severe HVD. Twenty-three feet received an isolated arthrodesis of the TMT-I joint (TMT-I), whereas 33 feet received an additional fusion between the base of the first and the second metatarsal bone (TMT-I/II). Various radiological parameters were determined preoperatively, 6 weeks and at a mean of 2 years postoperatively. RESULTS: The intermetatarsal angle (IMA) and the hallux valgus angle (HVA) were significantly lowered at both follow-up evaluations in both groups. In the TMT-I/II group, the initial reduction of HVA was significantly higher (29.3° vs 21.1°). This difference disappeared by the second follow-up, leaving no significant differences between both techniques at final follow-up. Radiological recurrence rates of HVD were comparable in both groups. CONCLUSIONS: Isolated TMT-I arthrodesis provides reliable radiological results in the correction of HVD. Whether additional fusion of the first and second metatarsal base should be routinely performed remains unclear. LEVELS OF EVIDENCE: Level 3.

Treatment options in PJI - is two-stage still gold standard?

Total knee arthroplasty (TKA) is a successful treatment for osteoarthritis with good clinical outcomes 1,2. Periprosthetic joint infection (PJI) in TKA has a low incidence between 0.5 and 3% but it is nevertheless one of the most dreadful complications 3-6. Two-staged revisions are considered to be the gold standard for revision in chronic PJI with infection eradication rates of over 90% 7. Recently, similar infection eradication rates after one-staged revision arthroplasty have been reported 8-10, raising the question whether the two-staged approach can still be considered the gold standard. We therefore performed a literature review to analyse the correlation of one-staged and two-staged TKA revisions with recurrent infection rates and functional outcomes. Studies concerning PJI treated by one- or two-staged revision published between 2000 and 2020 were retrieved by searching the databases PubMed/Medline and the Cochrane Database of Systematic Reviews. 29 studies were included in this qualitative synthesis. Mean follow-up was at 4.9 ± 2.6 years. The mean infection eradication rate after one-staged revision vs. two-staged revision in TKA was 87 ± 8.8% vs. 83 ± 11.7%. The functional outcome measured by the mean Knee Society Score (KSS) of one-staged revision vs. two-staged revision in TKA was 80 ± 5.9 vs. 80 ± 3.9 points. One-staged revision arthroplasty in TKA appears to have similar infection eradication rates and functional outcomes compared to two-staged revision arthroplasty. However, these results should be interpreted with caution, since selection bias may have played a significant role. Several criteria to guide the surgeon in selecting the appropriate procedure have been described, but the current recommendations are based on poor evidence as randomized controlled trials are lacking 11,12. Two-staged revision remains a successful treatment option which is rightly the gold standard. However, there is a variety of cases in which one-staged revision is a viable alternative, where similar success rates and functional outcome can be expected 7,13.

Effect of bone density and cement morphology on biomechanical stability of tibial unicompartmental knee arthroplasty.

BACKGROUND: Unicompartmental knee arthroplasty (UKA) offers good long-term survivorship and superior kinematics and function compared with total knee arthroplasty (TKA). However, revision rates are higher with aseptic loosening representing a major cause. Biomechanical stability depends on cement penetration. The goal of this study was to analyze the influence of cement morphology and bone density on primary stability of tibial UKA under physiological loading conditions in human tibiae. METHODS: Thirty-six tibial trays were implanted in fresh-frozen human cadaver knees and tested for primary stability using dynamic compression-shear testing. Prior to implantation, bone density had been quantified for all 18 tibiae. Postoperatively, cement penetration has been assessed on frontal cuts based on eight predefined parameters. The influence of bone density and cement morphology on biomechanical stability was determined using correlation and linear regression analysis. RESULTS: Mean failure load was 2691 ± 832.9 N, mean total cement thickness was 2.04 ± 0.37 mm, mean cement penetration was 1.54 ± 0.33 mm and mean trabecular bone mineral density (BMD) was 107.1 ± 29.3 mg/ml. There was no significant correlation between failure load and cement morphology (P > .05). Failure load was significantly positive correlated with trabecular BMD (r = 0.843; P < .0001) and cortical BMD (r = 0.432; P = .0136). CONCLUSIONS: Simulating physiological loading conditions, the failure load of tibial UKA is linearly dependent on the trabecular BMD. The observed parameters of cementation morphology seem capable of preventing failure at the bone-cement interface before inherent bone stability is reached. Further research is required to assess the usefulness of a preoperative assessment of bone quality for patient selection in UKA.

A cone beam CT based 3D-assessment of bony forefoot geometry after modified Lapidus arthrodesis.

BACKGROUND: Modified Lapidus arthrodesis (MLA) is a well-established treatment modality for hallux valgus deformities (HVD) associated with instability of the first ray. Although the three-dimensional (3D) nature of HVD has long been recognized, diagnostics still focus on plain radiographs. The objective of this study was to validate 3D Cone Beam CT (CBCT) in the perioperative assessment of HVD with focus on the alignment of the forefoot. METHODS: In a prospective clinical study, MLA was performed on 30 patients (25 females, 5 males; mean age: 63.2 years). Pre- and postoperatively standard radiographs and CBCT with full weight-bearing were acquired. For the CBCT based assessment, reproducible criteria have been defined, measured, and correlated with established radiological indicators. RESULTS: Evaluation of standard radiographic parameters (hallux-valgus angle [HVA], intermetatarsal angle 1-2 [IMA 1-2], distal metatarsal articular angle [DMAA], tibial sesamoid position [TSP]) showed significant improvement postoperatively. Comparison of measurements obtained from plain radiographs and CBCT were significantly correlated between both measuring techniques, indicating high reliability. Pronation of the first metatarsal and the sesamoids were significantly reduced by the procedure. Due to this repositioning effect, the second metatarsal head was elevated by 3.1mm, and the lateral sesamoid was lowered by 3.8mm. However, there was no correlation between the amount of pronation and conventional radiographic measures. CONCLUSIONS: Compared to plain radiographs, CBCT allows a more detailed view of the forefoot alignment in the coronal plain after MLA. MLA was able to recenter the sesamoids under der first metatarsal head and conversely led to elevation of the second metatarsal head.

Impact of a double-layer cementing technique on the homogeneity of cementation and the generation of loose bone cement fragments in tibial unicompartmental knee arthroplasty.

BACKGROUND: The objective of this study was to evaluate the impact of a single- vs. double-layer cementing technique on morphological cementation and the generation of microscopic cement layers or loose cement fragments in unicompartmental knee arthroplasty (UKA). METHODS: UKAs were implanted in 12 cadaver knees. The specimens were divided into two groups of comparable bone mineral density. Six UKAs were implanted using a single-layer cementing technique (group A) and six UKAs were implanted using a double-layer cementing technique (group B). Morphological cementation was assessed on nine cuts through the implant-cement-bone interface in the frontal plane. Loose bone cement fragments and the microscopically quality of layer formation were evaluated. RESULTS: Contact between bone and prosthesis was observed in 45.4% of interfaces in group A and 27.8% in group B (p = 0.126). The significant increase of areas without visible cement interlocking in the anteroposterior direction in group A (p = 0.005) was not evident in group B (p = 0.262). Penetration around the peg tended to occur more frequently in group B (67.5% vs. 90.6% p = 0.091). Scanning electron microscopy identified no evidence of fissure formations within the bilaminar cement mantle. Free bone cement fragments were documented in 66.7% in both groups with no difference concerning mass (p = 1.0). CONCLUSIONS: This in-vitro study showed a tendency towards a more homogenous cementation of tibial UKAs using a double-layer cementing technique, although most of the differences did not reach the level of significance. However, theoretical downsides of the double-layer cementing technique such as an increased formation of free bone fragments or a microscopically fissure formation within the cement layer could not be detected either.

Guided and Unguided Biopsy in the Diagnostic of Periprosthetic Infections of the Knee - Evaluation of an Evidence-based Algorithm. / Die gezielte und ungezielte Zupfbiopsie in der Abklärung periprothetischer Kniegelenksinfektionen ­ Evaluierung eines evidenzbasierten Algorithmus.

BACKGROUND: Periprosthetic joint infection (PPI) is one of the most common reasons for revision in total knee arthroplasty (TKA). Percutaneous synovial biopsy is considered as a well-established diagnostic tool in ambiguous cases of chronic pain after TKA. The exact number of undetected low-grade infections remains unclear. OBJECTIVES: The aim of this prospective study was to compare the diagnostic accuracy of arthroscopically guided and unguided synovial biopsy. Additionally, the prevalence of initially undetected PPI during synovial biopsy and revision surgery was assessed. MATERIALS AND METHODS: 40 patients suffering from chronic pain after TKA and the clinical suspicion of PPI were included in the study. Synovial biopsies were collected in a standardized manner first without and then with arthroscopic visual control. Using both techniques, six samples were collected each (5 for microbiology, 1 for histology). 19 patients, initially classified aseptic, underwent revision surgery later. RESULTS: The diagnosis of PPI was made in 10.0% of unguided biopsies (4 cases, 2× microbiologically, 2× histologically), 7.5% of arthroscopic biopsies (3 cases, 3× histologically) and 12.5% (5 cases, 3× histologically, 2× microbiologically) of all cases. Only histologic evaluation led to concordant positive findings using both techniques in two patients. The proportion of non-representative biopsies was twice as high after unguided tissue collection than after arthroscopic biopsy (30.0 vs. 15.0%). Microbiologic evaluation of arthroscopically collected biopsies did not lead to the diagnosis of PPI, which might have been essential to the selection of the appropriate antimicrobial therapy. During revision surgery the diagnosis of PPI was made in 22.2% of cases. CONCLUSIONS: In patients suffering from chronic pain after TKA, periprosthetic low-grade infection was diagnosed in a relevant proportion of cases. Therefore, synovial biopsies for histological and microbiological evaluation should be collected whenever there's clinical suspicion of PPI. For histological evaluation, samples should be collected using arthroscopic control and ideally multiple biopsies should be taken. For microbiological evaluation, excessive joint lavage should be avoided.

Influence of bone density on morphologic cement penetration in minimally invasive tibial unicompartmental knee arthroplasty: an in vitro cadaver study.

BACKGROUND: Unicompartmental knee arthroplasty is an established treatment option for anteromedial osteoarthritis. However, large registry studies report higher rates of aseptic loosening compared to total knee arthroplasty. The objective of this study was to assess the impact of bone density on morphological cement penetration. Moreover, an alternative regional bone density measuring technique was validated against the established bone mineral density assessment. METHODS: Components were implanted on the medial side of 18 fresh-frozen cadaver knees using a minimally invasive approach. Bone density has been quantified prior to implantation using Hounsfield units and bone mineral density. Morphological cement penetration has been assessed in different areas and was correlated with local bone density. FINDINGS: A highly significant correlation between Hounsfield units and trabecular bone mineral density was detected (r = 0.93; P < 0.0001), and local bone density was significantly increased in the anterior and posterior area (P = 0.0003). The mean cement penetration depth was 1.5 (SD 0.5 mm), and cement intrusion into trabecular bone was interrupted in 31.8% (SD 23.7%) of the bone-cement interface. Bone density was correlated significantly negative with penetration depth (r = - 0.31; P = 0.023) and positive with interruptions of horizontal interdigitating (r = + 0.33; P = 0.014). Cement penetration around the anchoring peg was not significantly correlated with bone density. INTERPRETATION: Areas with high bone density were characterized by significantly lower penetration depths and significantly higher areas without cement penetration. Anchoring pegs facilitate cement intrusion mechanically. Regional quantification of bone density using Hounsfield units is a simple but valuable extension to the established determination of bone mineral density.

Inter-Sectoral Collaboration in Municipal Health Centres: A Multi-Site Qualitative Study of Supporting Organizational Elements and Individual Drivers.

INTRODUCTION: Community health centres accommodating different professional groups are expected to improve inter-sectoral collaboration between primary care providers. This study aimed to identify what has been done to support inter-sectoral collaboration between municipal professionals and general practitioners in health centres, and to explore the interactions that emerge between these professionals at the operational level. METHODS: The study was a multi-site qualitative study carried out in four municipal health centres in a Danish region. The study was based on documents and qualitative interviews with general practitioners, and municipal professionals and administrators in each of the health centres. A content analysis was conducted. RESULTS: The study found that little attention had been given to the organizational prerequisites for enhanced inter-sectoral collaboration in the health centres. Even though some health centres had employed coordinators, these did not play a significant role as facilitators of collaboration partly due to a lack of political and managerial attention. At the operational level, inter-sectoral collaboration was limited to ad hoc interactions between professionals. Although these interactions could be useful, they did not evolve into more systematic forms of collaboration. CONCLUSION: The gap between policy visions and actual implementation efforts found in this study suggests that a more active and focused engagement from the political-administrative level is needed if the visions of increased inter-sectoral collaboration in health centres are to be realised.

A 30-Year Single-center Experience of Cementless Total Hip Arthroplasty With Spongy Metal Structured Implants: A Follow-up of a Previous Report.

BACKGROUND/AIM: The aim of this study was to analyze survivorship and functional outcome of cementless spongy metal structured total hip arthroplasty (THA) after ultra-long-term follow-up. PATIENTS AND METHODS: A total of 100 THAs in patients under 65 years at initial surgery were performed between 1985 and 1989 at our Department. Twenty patients (23 hips) were available for final follow-up. Implant survivorship and functional results (Merle d'Aubigné, SF-12) were assessed. RESULTS: At a mean follow-up of 30 years (range=27.7-31.7 years), the overall stem survival rate was 82.6% (19/23 stems) and the overall cup survival rate was 52.2% (12/23 cups). Revision surgeries were performed for aseptic loosening in all cases. Functional evaluation revealed good to excellent results in 16 patients (80%) Conclusion: Spongy metal structured cementless THA provides remarkable survivorship and excellent functional results even after ultra-long-term follow-up. Further research regarding modern implants, bearing surfaces etc. is required to assess survivorship and clinical outcomes of different implant designs.

Accuracy of a non-invasive CT-based measuring technique for cement penetration depth in human tibial UKA.

BACKGROUND: Aseptic loosening of the tibial component remains a major cause of failure in unicompartmental knee arthroplasty (UKA) and may be related to micro-motion at the cement-bone interface due to insufficient cement penetration depth. Cement penetration is therefore taken as an indicator of solid fixation strength and primary stability. However, its non-invasive clinical assessment remains difficult in vivo as conventional x-ray is prone to distortion and CT-scans (computed tomography) are difficult to assess due to metal artifacts. The purpose of this study was to develop and validate a reliable in vivo measuring technique of cement penetration depth in human tibial UKA. METHODS: In an experimental setting, twelve UKA were implanted in fresh-frozen human cadaver knees using a minimal-invasive medial approach. Cement penetration depth was then measured via 1) virtual 3D-models based on metal artifact reduced CT-scans and 2) histological evaluation of nine serial cross-section cuts through the implant-cement-bone-interface. Subsequently, a concordance analysis between the two measuring techniques was conducted. RESULTS: The average cement penetration depth was 1) 2.20 mm (SD 0.30 mm) measured on metal artifact reduced CT-scans and 2) 2.21 mm (SD = 0.42) measured on serial cuts (p = 0.956). The mean difference between both techniques was 0.01 mm (SD 0.31 mm) and the Person correlation coefficient was r = 0.686 (p = 0.014). All differences were within the upper and lower limit of agreement. There was no evidence of any significant proportional bias between both techniques (p = 0.182). CONCLUSIONS: CT-based non-invasive measurement of cement penetration depth delivers reliable results in measuring the penetration depth in tibial UKA. Thereby, it enables clinicians and researchers to assess the cement penetration for in vivo diagnostics in the clinical setting as well as in vitro biomechanical research with subsequent application of load to failure on the implant-cement-bone-interface.

[Megaimplants of the Proximal Femur: Current Concepts]. / AE-Beitrag: Megaimplantate am proximalen Femur: aktuelle Evidenz, Systemunterschiede und Portfolioempfehlung.

In addition to their outstanding significance in the field of tumor orthopaedics, megaprostheses are becoming increasingly important for revision arthroplasty. Despite their wide application, the reported complication and failure rates remain high. The analysis of failure mechanisms roughly allows a breakdown into mechanical and non-mechanical causes; soft-tissue failure, loosening and periprosthetic infection play outstanding roles. Each type of failure can be associated to a specific prosthetic component: To avoid soft tissue failure, muscular connection to the prosthesis is essential; to avoid loosening, the anchoring technique on the stem is crucial; to prevent infection, the surface condition or possibly the coating of the prosthesis seem to play major roles. Some fully-fledged proximal femoral replacement systems have become established on the market and have similar clinical outcomes. However, there are significant differences in anchoring techniques, modularity or module connections and soft tissue connection. In any case, the high failure rates show that there is great potential for future developments. Innovative suggestions for each component are certainly possible through cross-linking to already functioning systems. Together with new findings from basic research, future systems should be able to significantly reduce the rate of prosthetic failures.

Voluntary associations and co-production of health promoting activities for older adults: Experiences and policy lessons from Denmark.

Demographic transitions in Europe accentuate the need to develop innovative solutions for healthy ageing. One increasingly popular policy approach is co-production between local governments and voluntary community associations (VCOs) to promote activities for health and wellbeing among older adults. While co-production has been studied from the perspective of local governments there is limited knowledge regarding how voluntary associations perceive their conditions. This study aims to fill this gap using survey data from voluntary associations in Denmark. The investigation is based on an electronic survey (n = 263) of VCOs engaged in activities relevant for healthy ageing in three Danish municipalities. The survey addressed 13 issues and potential problems within four categories - ''members and volunteers', 'economics, 'media and the public' and '´politics and the local government'. The paper presents a relatively positive picture of the potentials in municipal-VCO collaboration. However, we also find that a sizeable number of VCOs point to problems and obstacles particular in regards to recruitment of members and economics. While the municipalities in our study have all developed strategies to support VCOs and to promote coproduction it seems that there are deficits in the implementation of the strategies. This leads us to conclude that municipalities must pay close attention to the issues and conditions for VCOs in order to succeed with their policy initiatives in this area.

Governing health equity in Scandinavian municipalities: The inter-sectorial challenge.

AIMS: Local governments in the Scandinavian countries are increasingly committed to reduce health inequity through 'health equity in all policies' (HEiAP) governance. There exists, however, only very sporadic implementation evidence concerning municipal HEiAP governance, which is the focus of this study. METHODS: Data are based on qualitative thematic network analysis of 20 interviews conducted from 2014 to 2015 with Scandinavian political and administrative practitioners. RESULTS: We identify 24 factors located within three categories; political processes, where insufficient political commitment to health equity goals outside of the health sector and inadequate economic prioritization budget curbs implementation. Concerning evidence, there is a lack of epidemiological data, detailed evidence of health equity interventions as well as indicators relevant for monitoring implementation. Concerted administrative action relates to a lack of vertical support and alignment from the national and the regional level to the local level. Horizontally within the municipality, insufficient coordination across policy sectors inhibits effective health equity governance. CONCLUSIONS: A shift away from 'health in all policies' based on a narrow health concept towards 'health equity for all policies' based on a broader concept such as 'sustainability' can improve ownership of health equity policy goals across municipal sectors.

Effect of lavage and brush preparation on cement penetration and primary stability in tibial unicompartmental total knee arthroplasty: An experimental cadaver study.

BACKGROUND: Unicompartmental total knee arthroplasty (UKA) is a well-established treatment option for unicondylar osteoarthritis, and generally leads to better functional results than tricompartimental total knee arthroplasty (TKA). However, revision rates of UKAs are reported as being higher; a major reason for this is aseptic loosening of the tibial component due to implant-cement-bone interface fatigue. The objective of this study was to determine the effects of trabecular bone preparation, prior to implantation of tibial UKAs, on morphological and biomechanical outcomes in a cadaver study. METHODS: Cemented UKAs were performed in 18 human cadaver knees after the bone bed was cleaned using pulsed lavage (Group A), conventional brush (Group B) or no cleaning at all (Group C, control). Morphologic cement penetration and primary stability were measured. RESULTS: The area proportion under the tibial component without visible cement penetration was significantly higher in Group C (21.9%, SD 11.9) than in both Group A (7.1%, SD 5.8), and Group B (6.5%, SD 4.2) (P=0.007). The overall cement penetration depth did not differ between groups. However, in the posterior part, cement penetration depth was significantly higher in Group B (1.9mm, SD 0.3) than in both Group A (1.3mm, SD 0.3) and Group C (1.4mm, SD 0.3) (P=0.015). The mode of preparation did not show a substantial effect on primary stability tested under dynamic compression-shear test conditions (P=0.910). CONCLUSION: Bone preparation significantly enhances cement interdigitation. The application of a brush shows similar results compared with the application of pulsed lavage.

Co-location as a Driver for Cross-Sectoral Collaboration with General Practitioners as Coordinators: The Case of a Danish Municipal Health Centre.

The issue of integrated care and inter-sectoral collaboration is on the health policy agenda in many countries. Yet, there is limited knowledge about the effects of the different policy instruments used to achieve this. This paper studies co-location as a driver for cross-sectoral collaboration with general practitioners (GPs) acting as coordinators in a municipal health centre. The purpose of the health centre, which is staffed by health professionals from municipal, regional and private sectors, is to provide primary health services to the citizens of the municipality. Co-locating these professionals is supposed to benefit e.g., elder citizens and patients with chronic diseases who frequently require services from health professionals across administrative sectors. Methodologically, the analysis is based on qualitative data in the form of semi-structured interviews with the health professionals employed at the health centre and with administrative managers from municipal and regional government levels. The study finds that co-location does not function as a driver for cross-sectoral collaboration in a health centre when GPs act as coordinators. Cross-sectoral collaboration is hampered by the general practitioners' work routines and professional identity, by organisational factors and by a lack of clarity concerning the content of collaboration with regard to economic and professional incentives.

Primary stability of unicompartmental knee arthroplasty under dynamic compression-shear loading in human tibiae.

BACKGROUND: The objective of our study was to evaluate the impact of a single- ("implant only") versus a double-layer ("implant & bone") cementing technique on the primary stability of unicompartmental tibial plateaus under dynamic compression-shear loading conditions in human tibiae. METHODS: Twelve fresh-frozen human knees of a mean donor age of 72.3 years were used to perform medial UKA under a less invasive parapatellar surgical approach. The tibiae were divided into two groups of matched pairs based on comparable trabecular bone mineral density. To assess the primary stability, a new method based on a combination of dynamic compression-shear testing, kinematic analysis of the tibial plateau migration relative to the bone and evaluation of the cement layer by CT-scans and fragments cut through the implant-cement-bone interface in the frontal plane was introduced. FINDINGS: For the "implant only" cementation technique the mean load to failure was 2600 (SD 675) N and for "implant & bone" it was 2820 (SD 915) N. Between the final load level at failure and the bone mineral density a significant correlation was found for the groups "implant only" (r(s) = 0.875) and "implant & bone" (r(s) = 0.907). INTERPRETATION: From our observations, we conclude that there is no significant difference between a single- ("implant only") and double-layer ("implant & bone") cementing technique in the effect on the primary stability of unicompartmental tibia plateaus, in terms of failure load, correlation between final load at failure and bone mineral density, migration characteristics, cement layer thickness and penetration depth.