The effect of hip and knee arthroplasty on oral anti-inflammatory use and the relationship to body mass index: results from the UK general practice research database.

OBJECTIVE: To determine the use of oral anti-inflammatory drugs in the year before and the 2 years after primary total hip (THR) or knee (TKR) replacement, and whether this varies according to Body mass Index (BMI). DESIGN: 28,068 THR's and 24,364 TKR's, with five matched controls per case were identified from the General Practitioner Research Database. Anti-inflammatory usage was categorized into "zero coverage" - no prescribed anti-inflammatory medication and ">80% coverage" - prescribed anti-inflammatory medication for greater than 80% of the days in the year. Secondary subset analysis was performed according to BMI. RESULTS: 1 year post-surgery the proportion of cases on >80% coverage reduced from 21% (95%confidence interval (CI): 20-22%) to 8% (95%CI: 7-10%) for THR and 21% (95%CI: 20-22%) to 13% (95%CI: 11-14%) for TKR, with no ongoing reduction at 2 years. Zero coverage increased at one and both time points. The proportion of THR's on >80% coverage increased with BMI pre-op. The magnitude in reduction post-op was similar across all BMI groups. The proportion of TKR's on >80% coverage pre-op was greatest in extreme BMI categories. The magnitude in reduction post-op was similar across all BMI groups. CONCLUSION: THR/TKR's reduce the need for anti-inflammatory medication with most benefit observed in the first post-operative year. Increasing BMI affects anti-inflammatory use both in the general population and those undergoing THR/TKR surgery but without strong evidence of a detrimental effect on the benefits of pain relief.

Development of in vivo muCT evaluation of neovascularisation in tissue engineered bone constructs.

Due to an increasing aging population the need for innovative approaches to aid skeletal repair and reconstruction is a significant socio-economic increasing problem. The emerging discipline of tissue engineering has sort to augment the growth and repair of bone loss particularly in areas of trauma, degeneration and revision surgery. However, the initiation and development of a fully functional vascular network are critical for bioengineered bone to repair large osseous defects, whether the material is osteosynthetic (poly (d,l)-lactic acid, PLA) or natural bone allograft. Quantification and three-dimensional visualization of new vessel networks remain a problem in bone tissue engineering constructs. A novel technique utilising a radio-opaque dye and micro-computed tomography (muCT) has been developed and applied to study angiogenesis in an impaction bone graft model. Tissue-engineered constructs combining human bone marrow stromal cells (HBMSC) with natural allograft and synthetic grafts (PLA) were impacted and implanted into the subcutis of MF-1 nu/nu mice for a period of 28 days. Microfil consisting of radio-opaque polymer was perfused through the mice and scanned using a Bench Top CT system for micro-computed tomography. Analysis of three-dimensional muCT reconstructions demonstrated an increase in vessel volume and vessel number in the impacted scaffolds/HBMC compared to scaffolds alone. Vessel volume: allograft/HBMSC=0.57 mm(3)+/-0.19; allograft=0.04 mm(3)+/-0.04; PLA/HBMSC=1.19 mm(3)+/-0.31; and PLA=0.12 mm(3)+/-0.01. Penetrating vessel number: allograft/HBMSC=22.33+/-3.21; allograft=3.67+/-1.153; PLA/HBMSC=32.67+/-8.33; and PLA=7.67+/-3.06. Type 1 collagen and von Willebrand factor immunohistochemistry in scaffold/HBMSC constructs indicated the osteogenic cell phenotype, and new blood vessel formation respectively. Contrast-enhanced 3D reconstructions facilitated the visualization and quantification of neovascularisation. This novel technique has been used to demonstrate neovascularisation in impacted tissue engineered constructs providing a facile approach with wide experimental application.

Is the rate of revision of 36 mm metal-on-metal total hip arthroplasties with Pinnacle acetabular components related to the year of the initial operation? an interrupted time-series analysis using data from the National Joint Registry for England and Wales.

AIMS: The aim of this study was to determine whether the rates of revision for metal-on-metal (MoM) total hip arthroplasties (THAs) with Pinnacle components varied according to the year of the initial operation, and compare these with the rates of revision for other designs of MoM THA. PATIENTS AND METHODS: Data from the National Joint Registry for England and Wales included 36 mm MoM THAs with Pinnacle acetabular components which were undertaken between 2003 and 2012 with follow-up for at least five years (n = 10 776) and a control group of other MoM THAs (n = 13 817). The effect of the year of the primary operation on all-cause rates of revision was assessed using Cox regression and interrupted time-series analysis. RESULTS: For MoM THAs involving Pinnacle components, those undertaken between 2007 and 2012 had higher rates of revision compared with those undertaken between 2004 and 2006 (hazard ratio (HR) 2.01; 95% confidence interval (CI) 1.57 to 2.57; p < 0.001). For THAs undertaken during and after 2007, the number of revisions per 1000 implant-years at risk significantly increased by 5.20 (95% CI 0.52 to 9.89; p = 0.033) compared with those undertaken before this time. In the control group, THAs undertaken between 2007 and 2012 also had higher rates of revision (HR 1.77; 95% CI 1.49 to 2.10; p < 0.001), with revisions per 1000 implant-years for those undertaken during and after 2007 significantly increasing by 6.13 (95% CI 1.42 to 10.83; p = 0.016). CONCLUSION: The five-year revision rates were significantly increased for all primary MoM THAs undertaken from 2007 onwards. Contrary to recent reports, this finding was not specific to those involving Pinnacle acetabular components and may be explained by increased surveillance and recent lowering of the threshold for revision. Cite this article: Bone Joint J 2018;100-B:33-41.

Vibration-assisted bone-graft compaction in impaction bone grafting of the femur.

The complications of impaction bone grafting in revision hip replacement includes fracture of the femur and subsidence of the prosthesis. In this in vitro study we aimed to investigate whether the use of vibration, combined with a perforated tamp during the compaction of morsellised allograft would reduce peak loads and hoop strains in the femur as a surrogate marker of the risk of fracture and whether it would also improve graft compaction and prosthetic stability. We found that the peak loads and hoop strains transmitted to the femoral cortex during graft compaction and subsidence of the stem in subsequent mechanical testing were reduced. This innovative technique has the potential to reduce the risk of intra-operative fracture and to improve graft compaction and therefore prosthetic stability.

The effect of frictional torque and bending moment on corrosion at the taper interface : an in vitro study.

The aim of this study was to assess the effect of frictional torque and bending moment on fretting corrosion at the taper interface of a modular femoral component and to investigate whether different combinations of material also had an effect. The combinations we examined were 1) cobalt-chromium (CoCr) heads on CoCr stems 2) CoCr heads on titanium alloy (Ti) stems and 3) ceramic heads on CoCr stems. In test 1 increasing torque was imposed by offsetting the stem in the anteroposterior plane in increments of 0 mm, 4 mm, 6 mm and 8 mm when the torque generated was equivalent to 0 Nm, 9 Nm, 14 Nm and 18 Nm. In test 2 we investigated the effect of increasing the bending moment by offsetting the application of axial load from the midline in the mediolateral plane. Increments of offset equivalent to head + 0 mm, head + 7 mm and head + 14 mm were used. Significantly higher currents and amplitudes were seen with increasing torque for all combinations of material. However, Ti stems showed the highest corrosion currents. Increased bending moments associated with using larger offset heads produced more corrosion: Ti stems generally performed worse than CoCr stems. Using ceramic heads did not prevent corrosion, but reduced it significantly in all loading configurations.

Phencyclidine disrupts long- but not short-term memory within a spatial learning task.

In the first experiment rats with 1, 2, 3 or 4 mg/kg phencyclidine (PCP), or saline injections were tested for acquisition or retention of a cheese board spatial task (dry land version of a water maze). Results indicate that relative to controls or rats with injections of 1 and 2 mg/kg PCP, rats with 3 or 4 mg/kg PCP injections were impaired in acquisition and retention of the task as measured by increased distances traveled to find the correct food location. This impairment was primarily observed in between days but not within days performance. In the second experiment rats with 4 mg/kg PCP or saline injections were tested for memory performance of a delayed spatial matching-to-sample task. Results indicate that relative to controls rats with 4 mg/kg PCP injections were not impaired at either 1-5 or 30 s delays. It is suggested that PCP through its blocking action of the NMDA receptor mediates long- but not short-term memory for spatial location information as well as the ability to retrieve previously learned spatial location information.

Neonatal piglet model of intraaortic balloon pumping: improved efficacy using echocardiographic timing.

BACKGROUND: Pediatric intraaortic balloon pumping (IABP) has met with little success because of technical difficulty in tracking rapid heart rates. This study was designed to evaluate the efficacy of M-mode echocardiography for IABP timing in a neonatal piglet model. METHODS: Two groups of piglets underwent mitral valve avulsion to create a model of shock. Group 1 (n = 8; mean weight, 7.7+/-1.8 kg) underwent IABP timed with both the ascending aortic pressure and M-mode echocardiogram. Group 2 (n = 6; mean weight, 7.5+/-1.4 kg) underwent two separate periods of IABP: one with echocardiographic timing and the second using standard timing points from the femoral arterial pressure tracing and electrocardiogram. Measurements included ascending aortic flow, left anterior descending arterial flow, ascending aortic pressure, left atrial pressure, and heart rate. RESULTS: Mitral valve avulsion produced a shock model with a significant decrease in mean aortic pressure and aortic flow and a significant increase in left atrial pressure and heart rate. Compared with the shock state, IABP in group 1 animals resulted in a significant increase in aortic flow (353+/-152 versus 454+/-109 mL/min; p < 0.05) and a significant decrease in left atrial pressure (23+/-6 versus 17+/-7 mm Hg; p < 0.05). Group 2 animals with echocardiogram-timed IABP had significantly increased aortic flow (365+/-106 versus 458+/-107 mL/min; p < 0.05) and mean aortic pressure (43+/-11 versus 52+/-8 mm Hg; p < 0.05). However, standard-timed IABP failed to show any improvement. CONCLUSIONS: In piglets with rapid heart rates, echocardiogram-timed IABP results in increased aortic flow and pressure and decreased left atrial pressure compared with standard-timed IABP.

High failure rates with a large-diameter hybrid metal-on-metal total hip replacement: clinical, radiological and retrieval analysis.

This study reports the mid-term results of a large-bearing hybrid metal-on-metal total hip replacement in 199 hips (185 patients) with a mean follow-up of 62 months (32 to 83). Two patients died of unrelated causes and 13 were lost to follow-up. In all, 17 hips (8.5%) have undergone revision, and a further 14 are awaiting surgery. All revisions were symptomatic. Of the revision cases, 14 hips showed evidence of adverse reactions to metal debris. The patients revised or awaiting revision had significantly higher whole blood cobalt ion levels (p = 0.001), but no significant difference in acetabular component size or position compared with the unrevised patients. Wear analysis (n = 5) showed increased wear at the trunnion-head interface, normal levels of wear at the articulating surfaces and evidence of corrosion on the surface of the stem. The cumulative survival rate, with revision for any reason, was 92.4% (95% confidence interval 87.4 to 95.4) at five years. Including those awaiting surgery, the revision rate would be 15.1% with a cumulative survival at five years of 89.6% (95% confidence interval 83.9 to 93.4). This hybrid metal-on-metal total hip replacement series has shown an unacceptably high rate of failure, with evidence of high wear at the trunnion-head interface and passive corrosion of the stem surface. This raises concerns about the use of large heads on conventional 12/14 tapers.

The management of compound leg injuries in the West Midlands (UK): are we meeting current guidelines?

The joint British Association of Plastic Surgeons and British Orthopaedic Association (BAPS/BOA) guidelines for the management of patients with open tibia fractures were published in 1991 and 1997 and provided a synopsis of injury epidemiology and best care. We present a retrospective review of 66 patients treated over a 2-year period (January 2001-February 2003) at a regional plastic surgery unit. There were 33 direct admissions and 33 transfers from other hospitals in which the average delay in transfer was 7.8 days (1-28) and in whom 26 (79%) patients had already undergone surgery. Plastic surgeons were involved in 46 (62%) of the 66 patient cohort and 27 (82%) transferred patients. The delay after admission until soft tissue cover was 3.8 days (0-15). Twenty-nine (44%) complications were recorded, 20 (69%) of these were in the transferred group and additional orthopaedic intervention was needed in 11 (42%) of patients who had been operated on in other hospitals. Despite widespread dissemination and teaching of the BAPS/BOA guidelines, complex extremity trauma is often not managed well in our region. There are unacceptable delays in admission, late communication, poor note keeping and follow up. The initial surgery/fixation is often sub-optimal and soft tissue reconstruction has to be considered at the least advantageous time period for the patient, leading to an increased hospital stay and complications.

Memory for spatial locations, motor responses, and objects: triple dissociation among the hippocampus, caudate nucleus, and extrastriate visual cortex.

Based on behavioral procedures aimed at measuring working or data-based memory for spatial location, response, and visual object information, it is shown that there is a triple dissociation among the hippocampus, caudate nucleus, and extrastriate visual cortex in mediating spatial location, response, and visual object information, respectively. The hippocampus appears to subserve only spatial location, the caudate nucleus only response, and the extrastriate visual cortex only visual object information. The results support the neurobiological foundation of the attribute memory model.