Critics of Unicompartmental knee replacement (UKR) highlight poor survivorship in national joint registries and argue that revision to Total Knee Replacement (TKR) is technically difficult with inferior function and survivorship compared to primary TKR. We prospectively reviewed outcomes of UKRs in our institution undergoing early revision to a TKR, comparing conventional revisions to those performed using computer navigation. 20 cases were identified, 7 conventional and 13 navigated. 13 were male and 7 female, mean age at primary UKR was 63.6 years (range: 47–81). Mean follow up time after revision was 5.2 years (2–9.5). Mean surgical time was 152 mins in conventional revisions and 163 mins for navigated. 43% of conventional cases required revision stems or augments, compared to 15% of conventional cases. Mean Oxford Knee Scores for revised knees were 32.8 in the conventional group and 34.64 in the navigated group, compared to 30.02 in the national joint registry. This compares to a mean Oxford score of 37.16 for primary TKRs in the registry. One of the conventional revisions required a further revision of the tibial component for loosening. This equates to a 95% suvivorship at mean 5 year follow up, or 1.10 revisions per 100 component years. Joint registry data had 1.97 revisions per 100 component years for UKR to TKR revisions, and 0.48 for primary TKRs. Our results are significantly improved compared to other published series of UKR revisions to TKRs. Only one other series has reported outcomes of these revisions using navigation. Despite small numbers, our results suggest that navigation makes revisions of UKRs more straightforward with similar surgical times. Fewer revision components were required with navigation and functional scores were marginally improved.
Despite extensive research, the cause of adolescent idiopathic scoliosis (AIS) is still largely unclear. Girls with AIS tend to be taller and leaner, and have a lower body-mass index (BMI) and lower bone mass, than do healthy girls. Recent MRI studies have shown the presence of relative anterior spinal overgrowth in girls with AIS. The lower bone mineral status and BMI could be related to dysfunctional central regulation pathway of growth, bodyweight, and bone metabolism. Following several interesting reports on the role of leptin in regulation of the above pathway in animals and human beings, our recent study has shown a low leptin concentration in girls with AIS girls compared with healthy adolescents. This finding leads to our new hypothesis that abnormal leptin bioavailability could be associated with the lower bodyweight, lower bone mineral density, and relatively disproportional endochondral skeletal growth in AIS. This study aimed to investigate the leptin bioavailability in girls with AIS. 53 girls with AIS and 27 healthy girls (aged 11–16 years) were recruited in this preliminary study. Clinical and anthropometric data were obtained. Blood samples were obtained for ELISA of leptin and soluble leptin receptor (sOB-R). Independent Student's t test and multivariate regression were used in group comparison.Introduction
Methods
Genetic predisposition is a key causal factor in adolescent idiopathic scoliosis (AIS), which is the most common form of spinal deformity. However, common quantitative genetic effect estimates such as hereditability have not been fully evaluated and reported for this disorder. We aimed to determine the sibling recurrent risk and hereditability of AIS in first-degree relatives of 513 Chinese patients with this disorder. Family members of 513 Chinese patients with AIS attending a scoliosis clinic were assessed. A diagnosis of AIS was made with the criteria of Cobb angle greater than 20°. The evaluation included clinical assessment and physical examination in a health screening centre by medical doctors with use of forward bending test. Any positive screening cases were referred to a scoliosis clinic for follow-up spinal radiograph. All radiographs were assessed by an orthopaedic surgeon in the scoliosis clinic. A population prevalence of scoliosis was obtained from the data of a territory-wide screening campaign. The prevalence of AIS among siblings of probands was measured both overall and divided by sex of siblings. The sibling recurrent risk (λs) was calculated for male and female siblings separately with reported population incidence of AIS.Introduction
Methods
Adolescent idiopathic scoliosis (AIS) is associated with low bone mineral density, which could be related to its etiopathogenesis. Apart from bone density, bone micro-architectures are equally important for better understanding of disease initiation and progression in AIS. Quantitative assessment of bone quality is hampered by the invasive nature of investigations, until recently when the high-resolution pQCT (XtremeCT) became available for revolutionary in-vivo microimaging and derivation of bone micro-architectural parameters. Our objective was to use this powerful instrument to study bone qualities in AIS and compare findings with those from healthy controls. 48 girls with AIS and 84 sex-matched healthy controls were recruited. Cobb angle was measured with standing radiographs, and imaging of the non-dominant distal radius was captured with XtremeCT according to a standard protocol.Introduction
Methods
The main challenge in management of adolescent idiopathic scoliosis (AIS) is to predict which curve will progress so that appropriate treatment can be given. We previously reported that low bone mineral density (BMD) was one of the adverse prognostic factors for AIS. With advancement in imaging technology, quantitative ultrasound (QUS) becomes a useful method to assess bone density and bone quality. The objective of this study was to assess the role of QUS as a radiation-free method to predict curve progression in AIS. 294 girls with AIS were recruited at ages 11–16 years and followed up until skeletal maturity. 269 age-matched healthy girls were recruited as controls. They provided the normal reference for calculation of Z score for QUS parameters. QUS measurements, including BUA (broadband ultrasound attenuation), VOS (velocity of sound) and SI (stiffness index) of the calcaneum, BMD of femoral neck, menarche history, ages, and Cobb angle of the major curve were recorded at baseline as independent variables. The predictive outcome was curve progression defined as an increase of Cobb angle of 6° or more. Logistic regression model and the ROC curve were used for statistical analysis.Introduction
Methods
Observation of sub-clinical neurological abnormalities has led to the proposal of a neuro-developmental etiologic model for AIS. Our research group have demonstrated longer latency in somatosensory–evoked potential (SSEP) and impaired balance control in AIS subjects. A previous pilot study compared the regional brain volume between right thoracic AIS subjects and normal controls. Significant regional brain differences were found relating to corpus callosum, premotor cortex, proprioceptive and visual centers. Most of these regions involved the brain unilaterally, indicating there might be abnormal asymmetrical development in the brain in right thoracic AIS. In this pilot study, we investigated whether similar changes are present in left thoracic AIS patients who differ from matched control subjects. Nine AIS female patients with atypical left thoracic AIS (mean age 14.8, mean Cobb angle 19°) and 11 matched controls as well as 20 right thoracic AIS (mean Cobb angle 33.8°) and 17 matched controls, underwent three-dimensional isotropic magnetization prepared rapid acquisition gradient echo (3D_MPRAGE) magnetic resonance (MR) imaging of the brain. Fully automatic morphometric analysis was used to analyse the MR images; it included brain-tissue classification into grey matter (GM), white matter (WM) and cerebrospinal fluid (CSF). and non-linear registration to a template brain. Tissue densities were compared between AIS subjects and controls. There was no significant difference between AIS subjects and normal controls when comparing absolute and relative (i.e. brain-size adjusted) volumes of grey and white matter. Using voxel-based morphometry, significant group differences (controls >
left AIS) were found in the density of WM in the genu of the corpus callosum, the left internal capsule (anterior arm) and WM underlying the orbitofrontal cortex of the left hemisphere. The above differences were not observed in the right AIS group. This first controlled study of regional tissue density showed that corpus callosum, which is the major commissural fiber tract, was different in the atypical left thoracic scoliosis while significant regional brain changes have not yet been found in those with typical right thoracic scoliosis. Further investigation is warranted to see whether the above discrepancy is related to laterality of the scoliotic curves and infratentorial neuroanatomical abnormalities. A larger sample and a longitudinal study is required to establish whether the brain abnormalities are predictive of curve progression.
