Fiona Berryman | University of Wolverhampton (original) (raw)

Papers by Fiona Berryman

Scoliosis and spinal disorders, Feb 26, 2016

Background: Loss of trunk height caused by scoliosis has been previously assessed using different... more Background: Loss of trunk height caused by scoliosis has been previously assessed using different mathematical formulae. However, these are of differing algebraic construction and will give a range of values for the same size of scoliosis curve. As such, the following study attempted to determine the most valid published formulae for calculating height loss caused by idiopathic scoliosis based on reported growth charts. Methods: The height and sitting height for a group with idiopathic scoliosis were measured. These were plotted on published growth standards. The size of the coronal curves and the thoracic kyphosis was measured. Height was corrected for the size of the scoliosis using the formulae and replotted on the growth standards. The data spread on the standard was analysed for significant differences between the median and the 5th or 95th centile, and between data outside the 5th and 95th centile. Results: The sitting to standing height ratio growth standard was used in the analysis as it minimised errors across the different growth standards, given that these standards come from different original populations. In the female group significant differences in the data spread were seen using the formulae of Bjure, Ylikoski and Hwang. Non-significant results were seen for the Kono and Stokes formulae. All formulae caused no significant differences in data spread across the growth standard in the males group. Conclusions: When assessing against growth standards, the formulae of Kono and Stokes are the most valid at determining height loss caused by idiopathic scoliosis.

Orthopaedic Proceedings, May 1, 2012

ABSTRACT Study Design Retrospective sequential patient series. Objectives To establish the relati... more ABSTRACT Study Design Retrospective sequential patient series. Objectives To establish the relationship between the magnitude of the deformity in scoliosis and patients' perception of their condition, as measured with Scoliosis Research Society-22 scores. Methodology A total of 93 untreated patients with adolescent idiopathic scoliosis were included retrospectively. The Cobb angle was measured from a plain radiograph, and volumetric asymmetry was measured by ISIS2 surface topography. The association between Scoliosis Research Society scores for function, pain, self-image, and mental health against Cobb angle and volumetric asymmetry was investigated using the Pearson correlation coefficient. Results Correlation of both Cobb angle and volumetric asymmetry with function and pain was weak (all < .23); these correlation values were not statistically significant. Correlation of Cobb angle and volumetric asymmetry with self-image, was higher, although still moderate (−.37 for Cobb angle and −.44 for volumetric asymmetry). Both were statistically significant (Cobb angle, p = .0002; volumetric asymmetry; p = .00001). Cobb angle contributed 13.8% to the linear relationship with self-image, whereas volumetric asymmetry contributed 19.3%. For mental health, correlation was statistically significant with Cobb angle (p = .011) and volumetric asymmetry (p = .0005), but the correlation was low to moderate (−.26 and −.35, respectively). Cobb angle contributed 6.9% to the linear relationship with mental health, whereas volumetric asymmetry contributed 12.4%. Conclusions Volumetric asymmetry correlates better with both mental health and self-image compared with Cobb angle, but the correlation was only moderate. This study suggests that a patient's own perception of self-image and mental health is multifactorial and not completely explained through present objective measurements of the size of the deformity. This helps to explain the difficulties in any objective analysis of a problem with multifactorial perception issues. Further study is required to investigate other physical aspects of the deformity that may have a role in how patients view themselves.

Orthopaedic Proceedings, Apr 1, 2012

Plain radiography has traditionally been used to investigate and monitor patients with adolescent... more Plain radiography has traditionally been used to investigate and monitor patients with adolescent idiopathic scoliosis. The X-ray allows a calculation of the Cobb angle which measures the degree of lateral curvature in the coronal plane. ISIS2 is a surface topography system which has evolved from ISIS, but with much higher precision and speed. It measures the three dimensional shape of the back using structured light and digital photography. This system has the benefit of not requiring any radiation. Lateral asymmetry is the ISIS clinical parameter estimating the curve of the spine in the coronal plane. The aim of this study was to compare this parameter to the Cobb angle measured on plain X-ray. Twelve patients with idiopathic adolescent scoliosis underwent both a standing AP spine X-ray and an ISIS2 scan on multiple occasions. Both scan and X-ray were done within one month of each other. No patient underwent surgery during the study period. The Cobb angle and the degree of lateral asymmetry were calculated. Twelve patients mean age 12.5 years (range 10-16) were investigated using both ISIS2 and X-ray. They had a mean 2.3 (1-5) combined investigations allowing for 30 comparisons. The correlation between the two measurements was r =0.63 (p=0.0002). The Cobb angle measured on ISIS2 was less than that measured by radiograph in 27 out of 30 comparisons. The mean difference between the measurements was mean 6.4° with a standard deviation of 8.2° and 95% confidence interval of 3.3° to 9.4°. In adolescent idiopathic scoliosis, curve severity and rib hump severity are related but measure different aspects of spinal deformity. As expected, these relate closely but not precisely. ISIS2 offers the promise of monitoring scoliosis precisely, without adverse effects from radiation. The small numbers in this series focus on the group of patients with mild to moderate curves at risk of progression. In this group, ISIS2 was able to identify curve stability or progression, without exposing the subjects to radiation.

Orthopaedic Proceedings, Jun 1, 2012

Introduction Monitoring of scoliosis is traditionally done with radiographs, which can be associa... more Introduction Monitoring of scoliosis is traditionally done with radiographs, which can be associated with an increased risk of cancer secondary to multiple exposures over many years. This study investigated whether the findings from surface topography can be used to monitor scoliosis curves and how much this method affects outcome scores in patients with scoliosis. This study therefore had two subsets: (1) to investigate whether lateral asymmetry (LA) from ISIS2 surface topography can predict radiographic Cobb angle, providing an alternative non-invasive means of monitoring patients with scoliosis (LA and Cobb subset); and (2) to establish the relationships between the magnitude of the deformity in scoliosis, measured by Cobb angle on radiograph and volumetric asymmetry (VA) with the ISIS2 surface topography, and the patient perception of self-image and mental health, measured with SRS-22 scores (Cobb, VA, and SRS subset). Methods In the LA and Cobb subset, 72 untreated patients with scoliosis (77 curves) with a Cobb angle of 55° or less were included in the study. They had clinical assessment, Cobb angle measurement taken from a standard radiograph, and surface topography done on the same day. A comparison of Cobb angle and LA was done. In the Cobb, VA, and SRS subset, 89 untreated patients with scoliosis were included in the study. They had clinical assessment, Cobb angle measurement of radiograph, and surface topography done on the same day along with SRS-22 questionnaires. A comparison correlation of SRS scores for function, pain, self-image, and mental health against Cobb angle and VA was undertaken. All statistical analysis was done with software R. Results In the LA and Cobb subset, for Cobb angle less than 55° on radiograph, ISIS2 was able to predict the Cobb angle within 13°. In the VA, Cobb, and SRS subset, Cobb angle contributed only about 10% to self-image, whereas VA contributed 14%. Cobb angle contributed about 6·2% to mental health, whereas VA contributed 8·6%. Conclusions Cobb angles display poor reliability, with estimates ranging from 3° to 10°. Even so, the 95% CIs on the prediction of Cobb angle from ISIS2 LA are too wide to use it alone to monitor spinal curvature. Whether or not LA is capable of monitoring change in curvature will be investigated as more longitudinal data are built up. VA correlates better with both mental health and self-image than does Cobb angle, but the correlation is still poor. Neither Cobb angle nor VA can be used to predict patient9s self-image or mental health. We are pursuing this study further to look at other parameters that may affect SRS-22 such as sex, age, type of deformity, waist asymmetry, and shoulder asymmetry.

Journal of Anatomy, May 15, 2021

The surgical strategy in adolescent idiopathic scoliosis (AIS) aims to recreate the symmetry of t... more The surgical strategy in adolescent idiopathic scoliosis (AIS) aims to recreate the symmetry of the torso. This requires the minimisation of both the size of the scoliosis and the angulation between the sides of the torso, along with the recreation of a normal thoracic kyphosis. This study uses predictive modelling to identify the significance of the value of the pre‐operative parameters, and the change in the magnitude of the parameters as a result of an operation on the shape of the torso using the ‘most prominent points’; two areas of maximum prominence on either side of the spine with x, y and z coordinates. The pre‐operative values, and the change in magnitude between the pre and post‐operative values, for scoliosis, kyphosis and skin angulation from a group of Lenke 1 convex to the right AIS were analysed with measures collected using Integrated Spine Imaging System 2 surface topography and compared with those without visible spinal deformity. The models best explained the z coordinate and least well explained the x coordinate, although there was a contribution to all of the models that remained unexplained. The parameters that affected the position of the coordinates in the model differed between the models. This confirms that surgically altering the shape of the spine and torso whilst correcting an AIS does not lead to a symmetrical torso. There are as yet, undefined factors which contribute to the shape of the torso and which if identified and corrected surgically would lead to greater symmetry post‐operatively.

Symmetry, Feb 13, 2019

Scoliosis results in a 3D asymmetry of the spine and torso. It is not clear what the variability ... more Scoliosis results in a 3D asymmetry of the spine and torso. It is not clear what the variability in 3D shape is in a non-scoliotic population, how much that is altered by scoliosis and what surgery does to that. This study is a 3D analysis of the shape of the torso in a cohort of non-scoliotic children that is then compared with a cohort of those with scoliosis both pre-and post-operatively. Procrustes analysis is used to examine the mean 3D shape. There is variability in shape in the non-scoliotic cohort. Scoliosis increases this asymmetry, particularly around the most prominent areas of the torso. Surgery alters the torso asymmetry but increases the difference in height between the right and the left with regard to the most prominent points on the torso. There is a degree of asymmetry seen in a non-scoliotic cohort of children. Scoliosis increases that asymmetry. Surgery alters the asymmetry but causes an increase in some of the 3D elements of the most prominent areas of the torso.

PubMed, 2008

Scoliosis deformity has been assessed using radiographic angle measurements. Surface topography s... more Scoliosis deformity has been assessed using radiographic angle measurements. Surface topography systems are an alternative and complementary methodology. Working systems include the original ISIS1 system, Quantec and COMOT techniques. Over the last five years the new ISIS2 (Integrated Shape Imaging System) has been developed from basic principles to improve the speed, accuracy, reliability and ease of use of ISIS1. The aim of this study was to confirm that ISIS2 3D back shape measurements are valid for assessment and follow up of patients with scoliosis. Three-dimensional back measurements were performed in Oxford. ISIS2 includes a camera/projector stand, patient stand with a reference plane, and Mac computer. Pixel size is approximately 0.5 mm with fringe frequency of approximately 0.16 fringes/mm ( approximately 6.5 mm/fringe). Clinical reports in pdf format are of coloured images with numerical values. Reports include a height map, contour plot, transverse section plots, coronal plot, sagittal sections and bilateral asymmetry maps. A total of 520 ISIS2 scans on 242 patients were performed from February 2006 to December 2007. There were 58 male patients (median age 16 years, SD 3.71, min 7, max 25) and 184 female patients (median age 14.5 years, SD 3.23, min 5, max 45). Average number of scans per patient was 2.01 with the range of 1-10 scans. Right sided thoracic curves were the most frequent pattern. The median values and 95% CI are reported of back length; pelvic rotation; flexion/extension; imbalance; lateral asymmetry; skin angle; kyphosis angle; lordosis angle; volumetric asymmetry. ISIS2 scoliosis measurements are non-invasive, low-cost, three-dimensional topographic back measurements which can be confidently used in scoliosis assessment and monitoring of curve progression.

Orthopaedic Proceedings, Jul 10, 2020

Orthopaedic Proceedings, May 2, 2019

Introduction We investigated predictors of poor outcomes following metal-on-metal hip arthroplast... more Introduction We investigated predictors of poor outcomes following metal-on-metal hip arthroplasty (MoMHA) revision surgery performed for adverse reactions to metal debris (ARMD), to help inform th...

Elsevier eBooks, 2021

Abstract The knee is one of the most complex joints in the human body. It is subject to millions ... more Abstract The knee is one of the most complex joints in the human body. It is subject to millions of steps during a lifetime and is regularly subjected to a force of several times body weight. Many knee computer models have been proposed and investigated to simulate the knee joint and to understand the kinematic and dynamic behavior of knee. This is useful for studying knee function and evaluating preclinical treatment options, including design of total knee replacement implants. However, the knee joint is one of the most challenging joints to be modeled. Many simplifications and assumptions have been made during knee joint modeling such as selection of the knee rotation axis, ligament material properties, and muscle activations. To reduce the limitations, these knee joint models are constantly being improved, often now using measured knee joint data and material properties to provide better results. In this chapter, various knee models are introduced, from generating three-dimensional knee computer models, to musculoskeletal knee joint models for kinematic and dynamic analyses and finite element knee joint models for stress analysis.

Spine, Oct 1, 2018

Study Design. A longitudinal cohort study. Objective. The aim of this study was to do the analysi... more Study Design. A longitudinal cohort study. Objective. The aim of this study was to do the analysis of the development of kyphosis and lordosis in the growing spine. Summary of Background Data. Previous studies have measured kyphosis and lordosis in different ways with differing techniques. None of the previous literature has a truly longitudinal design and there is disagreement as to whether there exists a difference between the development of kyphosis and lordosis between males and females. Methods. Repeated measures using Integrated Shape Imaging System Integrated Shape Imaging System 2 surface topography over 5 years of a group of children aged 5 to 16 years without spinal deformity. Longitudinal analysis was performed using linear mixed effects modeling. Results. There were 638 measures in 194 children. Both kyphosis and lordosis increased with age in both males and females (P < 0.001 for kyphosis and P ¼ 0.002 for lordosis). There was no statistical difference in the development of kyphosis between males and females (P ¼ 0.149). However, there was a significant difference in lordosis between males and females (P < 0.001) with female lordosis larger than that seen in males. Kyphosis and lordosis increased in a nonlinear fashion with age. Conclusion. Kyphosis and lordosis increase as children age. Between males and females there is no difference in the increase in the size of kyphosis, but there is difference in the size of lordosis with females having greater lordosis versus males at the same age.

Journal of Arthroplasty, Jul 1, 2019

Background: Surgeons currently have difficulty when managing metal-on-metal hip arthroplasty (MoM... more Background: Surgeons currently have difficulty when managing metal-on-metal hip arthroplasty (MoMHA) patients with adverse reactions to metal debris (ARMD). This stems from a lack of evidence, which is emphasized by the variability in the recommendations proposed by different worldwide regulatory authorities for considering MoMHA revision surgery. We investigated predictors of poor outcomes following MoMHA revision surgery performed for ARMD to help inform the revision threshold and type of reconstruction. Methods: We retrospectively studied 346 MoMHA revisions for ARMD performed at 2 European centers. Preoperative (metal ions/imaging) and intraoperative (findings, components removed/implanted) factors were used to predict poor outcomes. Poor outcomes were postoperative complications (including rerevision), 90-day mortality, and poor Oxford Hip Score. Results: Poor outcomes occurred in 38.5%. Shorter time (under 4 years) to revision surgery was the only preoperative predictor of poor outcomes (odds ratio [OR] ¼ 2.12, confidence interval [CI] ¼ 1.00-4.46). Prerevision metal ions and imaging did not influence outcomes. Single-component revisions (vs allcomponent revisions) increased the risk of poor outcomes (OR ¼ 2.99, CI ¼ 1.50-5.97). Intraoperative modifiable factors reducing the risk of poor outcomes included the posterior approach (OR ¼ 0.22, CI ¼ 0.10-0.49), revision head sizes 36 mm (vs <36 mm: OR ¼ 0.37, CI ¼ 0.18-0.77), ceramic-on-polyethylene revision bearings (OR vs ceramic-on-ceramic ¼ 0.30, CI ¼ 0.14-0.66), and metal-on-polyethylene revision bearings (OR vs ceramic-on-ceramic ¼ 0.37, CI ¼ 0.17-0.83). Conclusion: No threshold exists for recommending revision in MoMHA patients with ARMD. However postrevision outcomes were surgeon modifiable. Optimal outcomes may be achieved if surgeons use the posterior approach, revise all MoMHA components, and use 36 mm ceramic-on-polyethylene or metalon-polyethylene articulations.

Journal of Anatomy, Jun 15, 2017

The clinical assessment of scoliosis is based on the recognition of asymmetry. It is not clear wh... more The clinical assessment of scoliosis is based on the recognition of asymmetry. It is not clear what the degree of asymmetry is in a population without scoliosis, which could make the differentiation between abnormal and normal uncertain. This study defines the range of normality in certain parameters of torso shape that are also associated with the clinical assessment of scoliosis. This was done by analysing the surface topography of a group of 195 children serially measured over a 5-year period. The analysis considered both the spinal curvature and the relative position of shoulders, axillae and waist on each side. The bivariate relationships were examined using 95% confidence interval data ellipses. Our results showed that a degree of spinal curvature was seen, either as a main thoracic or main thoracolumbar curve. The distribution of the data about a mean point is illustrated by 95% confidence interval (CI) data ellipses with shoulder, axilla and waist data plotted against spinal curvature. The mean values were close to zero (exact symmetry) for all of the measured parameters, with the ellipses showing little differences in the distributions. We conclude that mild asymmetry of the measured torso parameters is normal. These results define what is normal and beyond what point asymmetry becomes abnormal. This information is of use for those managing and counselling patients with scoliosis both before and after surgery.

International Journal of Speech Technology, Oct 21, 2011

Accent is a reflection of an individual speaker's regional affiliation and is shaped by the speak... more Accent is a reflection of an individual speaker's regional affiliation and is shaped by the speaker's community background. This study investigated the acoustic characteristics of two British regional accents-the Birmingham and Liverpool accents-and their correlations from a different approach. In contrast to previous accent-related research, where the databases are formed from large groups of single-accent speakers, this study uses data from an individual who can speak in two accents, thus removing the effects of inter-speaker variability and facilitating efficient identification and analysis of the accent acoustic features. Acoustic features such as formant frequencies, pitch slope, intensity and phone duration have been used to investigate the prominent features of each accent. The acoustic analysis was based on nine monophthongal vowels and three diphthongal vowels. In addition, an analysis of variance of formant frequencies along the time dimension was performed to study the perceived effects of vocal tract shape changes as the speaker switches between the two accents. The results of the analysis indicate that the formant frequencies, pitch slope, the intensity and the phone duration all vary between the two accents. Classification testing using linear discriminant analysis showed that intensity had the strongest effect on differentiating between the two accents followed by F3, vowel duration, F2 and pitch slope.

The bone & joint journal, May 1, 2017

To determine ten-year failure rates following 36 mm metal-on-metal (MoM) Pinnacle total hip arthr... more To determine ten-year failure rates following 36 mm metal-on-metal (MoM) Pinnacle total hip arthroplasty (THA), and identify predictors of failure. Patients and Methods We retrospectively assessed a single-centre cohort of 569 primary 36 mm MoM Pinnacle THAs (all Corail stems) followed up since 2012 according to Medicines and Healthcare Products Regulation Agency recommendations. All-cause failure rates (all-cause revision, and non-revised cross-sectional imaging failures) were calculated, with predictors for failure identified using multivariable Cox regression. Results Failure occurred in 97 hips (17.0%). The ten-year cumulative failure rate was 27.1% (95% confidence interval (CI) 21.6 to 33.7). Primary implantation from 2006 onwards (hazard ratio (HR) 4.30; 95% CI 1.82 to 10.1; p = 0.001) and bilateral MoM hip arthroplasty (HR 1.59; 95% CI 1.03 to 2.46; p = 0.037) predicted failure. The effect of implantation year on failure varied over time. From four years onwards following surgery, hips implanted since 2006 had significantly higher failure rates (eight years 28.3%; 95% CI 23.1 to 34.5) compared with hips implanted before 2006 (eight years 6.3%; 95% CI 2.4 to 15.8) (HR 15.2; 95% CI 2.11 to 110.4; p = 0.007). Conclusion We observed that 36 mm MoM Pinnacle THAs have an unacceptably high ten-year failure rate, especially if implanted from 2006 onwards or in bilateral MoM hip patients. Our findings regarding implantation year and failure support recent concerns about the device manufacturing process. We recommend all patients undergoing implantation since 2006 and those with bilateral MoM hips undergo regular investigation, regardless of symptoms.

Journal of Anatomy, May 31, 2016

The Haller index is a ratio of thoracic width and height, measured from an axial CT image and use... more The Haller index is a ratio of thoracic width and height, measured from an axial CT image and used to describe the internal dimensions of the thoracic cage. Although the Haller index for a normal thorax has been established (Haller et al. 1987; Daunt et al. 2004), this is only at one undefined vertebral level in the thorax. What is not clear is how the Haller index describes the thorax at every vertebral level in the absence of sternal deformity, or how this is affected by age. This paper documents the shape of the thorax using the Haller index calculated from the thoracic width and height at all vertebral levels of the thorax between 8 and 18 years of age. The Haller Index changes with vertebral level, with the largest ratio seen in the most cranial levels of the thorax. Increasing age alters the shape of the thorax, with the most cranial vertebral levels having a greater Haller index over the mid thorax, which does not change. A slight increase is seen in the more caudal vertebral levels. These data highlight that a 'one size fits all' rule for chest width and depth ratio at all ages and all thoracic levels is not appropriate. The normal range for width to height ratio should be based on a patient's age and vertebral level.

Scoliosis and spinal disorders, Nov 20, 2017

Background: Adolescent idiopathic scoliosis (AIS) causes asymmetry of the torso, and this is ofte... more Background: Adolescent idiopathic scoliosis (AIS) causes asymmetry of the torso, and this is often the primary concern of patients. Surgery aims to minimise the visual asymmetry. It is not clear how scoliosis makes the torso asymmetric or how scoliosis surgery changes that asymmetry when compared to the distribution of asymmetries seen in a non-scoliotic group of normal controls. Methods: Surface topography images were captured for a group with AIS both pre-operatively and postoperatively. Identifiable points were compared between the images to identify the effects of AIS on the shape of the torso by looking at the relative heights and distances from the midline of the shoulders, axillae and waist in a two-dimensional coronal view. This was then compared to a previously reported group of normal non-scoliotic children to analyse whether surgery recreated normality. Results: There were 172 pairs of images with 164 females and 8 males, mean age at pre-operative scan of 13. 7 years. The normal group was 642 images (237 females and 405 males) from 116 males and 79 females, mean age of 12.5 years. The curve patterns seen in the scoliotic group matched the patterns of a main thoracic curve (n = 146) and main thoracolumbar curve (n = 26). The asymmetries seen in both shoulders, axillae and waist were different between the two different types of curve. Across both groups, the shoulder asymmetry was less than that of the corresponding axillae. There was a statistically significant reduction in all asymmetries following surgery in the main thoracic group (p < 0.001). This was not seen in the main thoracolumbar group, thought to be due to the small sample size. In the main thoracic group, there were statistically significant differences in the asymmetries between the post-operative and normal groups in the shoulders and axillae (p < 0.001) but not the waist. Conclusions: This paper demonstrates quantitatively the range of asymmetries seen in the AIS torso and the degree to which surgery alters them. Surgery does not recreate normality but does cause a statistically significant change in torso shape towards that seen in a non-scoliotic group.

Journal of Anatomy, Apr 4, 2022

The relationship between the sagittal shape of the cervical spine and that of the thoracolumbar s... more The relationship between the sagittal shape of the cervical spine and that of the thoracolumbar spine is established in the normal spine. Adolescent idiopathic scoliosis (AIS) is recognised as a change in the shape of the spine in both the coronal and sagittal planes. The effects of AIS on the alignment of the cervical spine, including the effects of surgery, has been less well studied. The objective of this study was to identify, using regression analysis, the significant relationships between the alignment of the thoracolumbar spine, in both the coronal and sagittal planes, and the sagittal alignment of the cervical spine in AIS. This study used coronal and sagittal radiographic measures from a group with AIS, both pre and post-operatively, which were analysed using multiple linear regression methods to identify significant parameters that explain the sagittal shape of the cervical spine. There were 51 pairs of pre and post-operative radiographs analysed, 40 of which were Lenke 1 curves and 11 Lenke 3 curves. Posterior spinal fusion was performed for all. The significant parameters pre-operatively were T1 slope, thoracic kyphosis, lumbar lordosis and SVA with an R2 value of 78%. Post-operatively, the significant parameters were T1 slope, thoracic kyphosis, lumbar lordosis and thoracolumbar scoliosis with an R2 of 63%. The sagittal alignment of the cervical spine in AIS is related to the shape of key parameters in the rest of the spine. Changes in the cervical sagittal shape occur to compensate for changes in shape to the rest of the spine that occur as a consequence of surgery. This has implications for the understanding of how the compensatory mechanisms of the spine are used to maintain a horizontal gaze, along with prediction of the effects of surgery on the shape of the spine.

Hip International, Jul 17, 2022

Background: Studies investigating changes in blood metal ion levels during the second decade of t... more Background: Studies investigating changes in blood metal ion levels during the second decade of the implant lifetime in MoM hip resurfacing patients are scarce. Methods: Patients implanted with either Birmingham Hip Resurfacing (BHR) or Articular Surface Replacement (ASR) hip resurfacings with more than 10 years follow-up and repeated blood metal ion measurements were identified at two large specialist European arthroplasty centres. After excluding patients with initial metal ion levels above 7 ppb, the proportion of patients with an increase in blood metal ion levels above previously validated implant-specific thresholds (cobalt 2.15 ppb for unilateral implants, cobalt or chromium 5.5 ppb for bilateral) was assessed. Results: We included 2743 blood metal ion measurements from 457 BHR patients (555 hips) and 216 ASR patients (263 hips). Of patients with initial metal ion levels below implant specific thresholds, increases in cobalt or chromium level, respectively, to above these thresholds during the second decade were seen as follows: unilateral BHR (cobalt=15.6%), unilateral ASR (cobalt=13.8%), bilateral BHR (cobalt=8.2%, chromium=11.8%), bilateral ASR (cobalt=8.5%, chromium=4.3%). Measurement-to-measurement changes exceeding +2.15 ppb or +5.5 ppb were, however, uncommon during the second decade. Subgroup results with small diameter (<50 mm) implants were similar. Conclusions: We recommend less frequent blood metal-ion measurements are needed (every 3 to 5 years) for hip resurfacing patients if initial values were below 7ppb.

Scoliosis and spinal disorders, Jul 20, 2016

After publication of this article [1] the author brought to our attention that the formula of Sto... more After publication of this article [1] the author brought to our attention that the formula of Stokes in Table 1 is incorrect. The correct formula is y = (1 + 0.066x + 0.0084x 2)/ 10 where x represents the mean Cobb angle of the largest two curves in the scoliosis and y the height loss in centimetres.