There has recently been a proliferation of image-based knee arthroplasty systems which utilize pre-operative radiological analysis of a patient's anatomy to identify the bone cuts required to correct their mechanical alignment. The aim of this was to assess the accuracy of one such system (Visionaire™, Smith and Nephew Inc.©) Eleven cadavers were imaged using the Smith and Nephew Visionaire® MRI protocol to enable the production of cutting blocks individualized to the various specimens. These cutting blocks were then used to perform knee replacements on all cadavers. Post-operatively the validated Perth CT protocol was used to assess the position and rotational profile of each implant. These measurements were then compared to the pre-operative plan in order to assess the accuracy of implant placement. Relative to the pre-operative target parameters, the femoral components were aligned in a mean 0.048° valgus (95% CI – 0.36° to 1.32°) with 1.8° extension (95% CI −0.1° to 4.5°) and externally rotated by a mean 0.66° (95% CI 1.08° internal rotation to 2.4° external rotation.) The tibial components were in a mean 0.29° of varus (95% CI – 0.68° to 1.27°) with a posterior tibial slope of 90.5° (95% CI 89.6° to 92.6°) and internally rotated by a mean 1.7° (range 10.1° internal rotation to 1.1° external rotation.) The findings of our study suggest that the Visionaire system can produce accurate coronal implant alignment. The saggital and rotational alignment was not as reliable although these parameters may have been more prone to adverse influence by the limitations of the cadaveric model. Patient-matched knee arthroplasty technology offers significant potential benefits to both patient and surgeon and warrants further clinical investigation.
There is evidence that various anatomical structures have altered morphology with ageing, and anecdotal evidence of changing lumbar spinous process (LSP) morphology with age. This study aims to clarify the influence of age on LSP morphology, and on lumbar spine alignment. 200 CT scans of the abdomen were reformatted with bone windows allowing precise measurement of LSP dimensions and lumbar lordosis. Observers were blinded to patient demographics. Inter-observer reliability was confirmed. The smallest LSP is at L5. The male LSP is on average 2-3mm higher and 1mm wider than the female LSP. LSP height increases significantly with age at every level in the lumbar spine (P<10-5 at L2). The LSPs increase in height by 2-5mm between 20-85 years of age (P<10-6), which was as much as 31% at L5 (P<10-8). Width increases proportionally more, by 3-4mm or greater than 50% at each lumbar level (P<10-11). Lumbar lordosis decreases in relation to increasing LSP height (P<10-4) but is independent of increasing LSP width (P=0.2). The height and width of the spinous processes increases with age. Increases in spinous process height are related to a loss of lumbar lordosis and may contribute to sagittal plane imbalance.
The Lumbar Spinous Processes (LSP) have an important anatomical and biomechanical function protecting the neural structures in the spinal canal, and as an anchor for the inter and supraspinous ligaments, and the inter-segmental paraspinal muscles. They also influence access to the spinal canal for neural decompressive surgical procedures. More recently the LSPs have attracted increased interest as a site for surgical device attachment in an attempt to both decrease the symptoms of spinal stenosis, and as a site for intersegmental stabilization without formal fusion. There is evidence that various anatomical structures have altered morphology with ageing, and there is anecdotal evidence of changing LSP morphology with age. This study aims to clarify the influence of age on LSP morphology, and on lumbar spine alignment. 200 CT scans of the abdomen were reformatted with bone windows in sagittal and coronal planes allowing precise measurement of LSP dimensions, and Lumbar Lordosis. Observers were blinded to patient demographics. Inter-observer reliability was examined. Data was analysed by an independent statistician. The smallest LSP is at L5. The male LSP is on average 2–3mm higher and 1mm wider than the female LSP. LSP height increases significantly with age at every level in the lumbar spine (p<
10-5 at L2). The LSPs increase in height by 2–5mm between 20–85 years of age (p<
10-6), which was as much as 31% at L5 (p<
10-8). Width increases proportionally more, by 3–4mm or greater than 50% at each lumbar level (p<
10–11). Lumbar lordosis decreases in relation to increasing LSP height (p<
10-4) but is independent of increasing LSP width (p=0.2). This study demonstrates that the dimensions of the LSP change with age. Increases in LSP height occur with age. More impressive increases in LSP width occur with advancing age. This study suggests that loss of lumbar lordosis is correlated with changing LSP morphology. The increased width of the LSP with age influences access to the spinal canal, particularly if midline-preserving approaches are attempted in the ageing population. There is increased bone volume for bone grafting procedures with increasing age. The reduced distance between LSPs with age may influence design of implants that stabilize this region of the spine, and occur not only as a result of disc space narrowing, but also as a consequence of increased LSP dimensions.
Acute haematogenous osteomyelitis in children is relatively uncommon but delay in diagnosis and inadequate treatment can result in significant morbidity. Most recently evidence has suggested conservative treatment with adequate antibiotic therapy should be the mainstay, with provision for surgical intervention in those who fail to respond to conservative management. The outcome of primary management has been evaluated in this review. Retrospective analysis of an osteomyelitis database was conducted on individuals presenting to Auckland’s Starship and Middlemore Hospital with an ICD-10 diagnosis of Osteomyelitis between January the 1st 1999 and December the 31st 2008. 813 children fulfilled the criteria for inclusion into this review. The annual incidence of acute haematogenous osteomyelitis in the paediatric population in Auckland over this period was approximately 1:4,000. 64% were male and 36% were female. The majority were New Zealand European (35%), with the other significant ethnic groups represented being New Zealand Maori (22%), and Pacific Island (30%). 23% of patients were aged less than three. 51% of patients were between three and ten, and 26% older than ten. Only 32% had an elevated white cell count on admission. A responsible pathogen was isolated in 50% with the most common being Staphylococcus aureus, which was isolated in 77% of this group. Diagnosis was made radiologically in 66%, clinically in 27%, and surgically after exploration in 7%. The most common site of osteomyelitis was the femur in 254 individuals, followed by the tibia in 198 individuals. 49 had multi-focal involvement. Flucloxacillin was the most common antibiotic used, with 510 individuals being administered flucloxacillin at one point in time during their management. The average length of treatment was 43.7 days, which included intravenous therapy of 22.3 days, and oral therapy of 21.4 days. 60% had a range of duration of therapy from greater than three weeks through to six weeks. 44% required surgical intervention. The relapse rate was 6.8%. The average duration till relapse was 5.8 months. Only 1.7% of the total population went on to develop chronic osteomyelitis. The incidence of paediatric acute haematogenous osteomyelitis in this population appears to be relatively high. The average length of treatment was longer than that now reported to be successful for eradication. This could possibly be a factor in the relatively low rate of relapse and low subsequent rate of chronic osteomyelitis.
