H.A. Anwar

Circulating levels of cobalt and chromium from metal-on-metal hip replacement are associated with CD8+ T-cell lymphopenia

We carried out a cross-sectional study with analysis of the demographic, clinical and laboratory characteristics of patients with metal-on-metal hip resurfacing, ceramic-on-ceramic and metal-on-polyethylene hip replacements. Our aim was to evaluate the relationship between metal-on-metal replacements, the levels of cobalt and chromium ions in whole blood and the absolute numbers of circulating lymphocytes. We recruited 164 patients (101 men and 63 women) with hip replacements, 106 with metal-on-metal hips and 58 with non-metal-on-metal hips, aged < 65 years, with a pre-operative diagnosis of osteoarthritis and no pre-existing immunological disorders. Laboratory-defined T-cell lymphopenia was present in 13 patients (15%) (CD8(+) lymphopenia) and 11 patients (13%) (CD3(+) lymphopenia) with unilateral metal-on-metal hips. There were significant differences in the absolute CD8(+) lymphocyte subset counts for the metal-on-metal groups compared with each control group (p-values ranging between 0.024 and 0.046). Statistical modelling with analysis of covariance using age, gender, type of hip replacement, smoking and circulating metal ion levels, showed that circulating levels of metal ions, especially cobalt, explained the variation in absolute lymphocyte counts for almost all lymphocyte subsets.

The effect of metal ions in solution on bacterial growth compared with wear particles from hip replacements

The biological significance of cobalt-chromium wear particles from metal-on-metal hip replacements may be different to the effects of the constituent metal ions in solution. Bacteria may be able to discriminate between particulate and ionic forms of these metals because of a transmembrane nickel/cobalt-permease. It is not known whether wear particles are bacteriocidal. We compared the doubling time of coagulase negative staphylococcus, Staphylococcus aureus and methicillin resistant S. aureus when cultured in either wear particles from a metal-on-metal hip simulator, wear particles from a metal-on-polyethylene hip simulator, metal ions in solution or a control. Doubling time halved in metal-on-metal (p = 0.003) and metal-on-polyethylene (p = 0.131) particulate debris compared with the control. Bacterial nickel/cobalt-transporters allow metal ions but not wear particles to cross bacterial membranes. This may be useful for testing the biological characteristics of different wear debris. This experiment also shows that metal-on-metal hip wear debris is not bacteriocidal.

Removing Symptomatic Gallstones at their First Emergency Presentation

INTRODUCTION Early operations for symptomatic gallstones are gaining favour as the complication rate is thought to be lower and it reduces the overall morbidity. This study was performed to clarify how frequently early operations were being performed and what benefits resulted. PATIENTS AND METHODS Case notes of 171 patients who underwent laparoscopic cholecystectomy at Princess Alexandra Hospital Harlow were retrospectively reviewed. They were grouped according to their initial diagnosis (cholelithiasis, acute cholecystitis) and the delay to surgery (early, interval). Forty-one cases were excluded as they either had incomplete notes or the initial diagnosis was a different manifestation of gallstones such as pancreatitis. Those receiving interval operations were then grouped according to the mode of their initial presentation. A total of 130 case notes were analysed. RESULTS The delay for an interval operation was 3-6 months compared with less than 2 weeks for early operations. Of patients with acute cholecystitis, 43% had early operations but only 12% of patients with cholelithiasis. Waiting for interval operations was associated with multiple re-admissions equivalent to an average of one extra presentation to accident and emergency per patient. This was particularly marked if the initial presentation was to accident and emergency rather than outpatients (P = 0.003). Complication rates were also higher in the interval group. CONCLUSIONS Early cholecystectomy on the next available list is likely to reduce morbidity and the long-term in-patient burden so should be recommended for all patients presenting as an emergency with symptomatic gallstones.

Cauda equina syndrome versus saddle embolism.

We discuss a case of saddle embolism with a clinical presentation similar to cauda equina syndrome in a 79-year-old woman with a history of ischaemic heart disease. Saddle embolus is very rare but one of an array of visceral causes for back and leg pain. This case highlights diagnostic difficulties, particularly in patients with multiple disorders. A high index of suspicion for vascular conditions must be exercised in cases of arterial dysfunction presenting with back pain.

Segmental pelvic correlation (SPeC): a novel approach to understanding sagittal plane spinal alignment.

BACKGROUND CONTEXT Lumbar lordosis (LL) correlates with pelvic morphology, and it has been demonstrated that as LL increases, the inflection point and apex of lordosis move cranially. This suggests that each segment of the lumbar spine relates to pelvic morphology in a unique way. OBJECTIVES This study aimed to establish whether there is a direct relationship between pelvic morphology and lumbar segmental angulation in the sagittal plane. STUDY DESIGN A retrospective analysis of 41 patient radiographs was carried out. PATIENT SAMPLE Inclusion criteria included patients with full length standing anterioposterior and lateral radiographs of the spine from base of occiput to proximal femora, with clearly visible vertebral end plates from T12 to S1 and a thoracic kyphosis (TK) and LL within the normal range. Patients were excluded if they had a coronal spinal deformity affecting the lumbar spine, chronic back pain, spondylolisthesis, spondylolysis, congenital scoliosis, or skeletal dysplasia. OUTCOME MEASURES Spinopelvic radiographic parameters of pelvic incidence (PI), LL, TK, and segmental angulation at each level from L1 to the sacrum were the outcome measures. METHODS Forty-one lateral whole spine radiographs with normal sagittal profiles from the spinal deformity clinic were retrospectively reviewed. Pelvic incidence, LL, TK, and segmental angulation at each level from L1 to the sacrum were measured (from end plate to end plate), distinguishing the vertebral body and intervertebral disc contribution. Pearson correlation coefficients were used to analyze any relationship between pelvic parameters and segmental angulation. RESULTS A strong correlation was found between PI and LL. Pelvic incidence correlated strongly with the L1 and L2 motion segments (p=.0001, p=.03), notably at the intervertebral discs but not the L4 and L5 motion segments. The proportion of total LL contributed at L4-L5 and L5-S1 reduced as PI increased. CONCLUSIONS Pelvic incidence can predict segmental angulation. Although the majority of LL is produced at the L4 and L5 motion segments, cephalad lumbar segments sequentially become increasingly important as PI increases. This describes a continuum where the L1 and L2 motion segments crucially fine-tune total LL according to PI. This allows segmental abnormalities to be identified when compensation in adjacent segments maintain normal total LL. It also paves the way for anatomical segmental reconstruction in degenerative adult deformity based on pelvic morphology.

Reply to letter concerning "Segmental Pelvic Correlation (SPeC): a novel approach to understanding sagittal plane spinal alignment".

We would like to compliment Anwar et al. [1] for their excellent article and novel perspective on segmental pelvic correlation (SPeC) in sagittal spinopelvic balance. First, we would like to declare that we agree that correcting the sagittal alignment at each segment is very important to restore individual “spinopelvic harmony.” However, we doubt if the pelvic incidence (PI) can predict individual segmental angulation (as the conclusion of the authors), especially when the following deficiencies exist in the patients sample and data processing of their study. In Anwar et al.’s [1] study, the 41 patients included have a mean age of 17 years with a range from 11 to 36 years. This means that the majority of the patients are juveniles. The PI is an anatomical parameter that remains constant after the end of bone growth. However, the PI is not constant, but increased significantly during adolescence because of the increased pelvic tilt and sacral slope [2]. In addition, as one of the most important evidences of Anwar et al.’s [1] study, the four types of classification of lumbar lordosis (LL) by Barrey et al. [3] are also based on adults. So, the SPeC found in Anwar et al.’s [1] study may not be a universal rule about adult patients. For instance, the immature vertebral physeal (endplate) in juvenile patients may directly influence the vertebral shape that results in lumbar vertebra body lordosis increasing. And this result may make authors overestimate the correlation between vertebral motion segment lordosis and PI. The LL varied to adjust an individual’s center of gravity and bring it over the hips and lower limbs [2,3]. It is hard to understand why the gravity axis parameter (such as sagittal vertical axis) was not considered in Anwar et al.’s [1] study. Gelb et al. [4] studied asymptomatic middleand old-aged volunteers and determined that increasing age corresponded to a more anterior gravity axis with loss of LL. Given the young age of patients in Anwar et al.’s [1] study, the gravity axis of the patients may be generally backward and then leads to the greater LL (which is not completely due to PI). Anwar et al. [1] indicate that the SPeC is very important in preoperative planning of deformity correction and fusion in the degenerative patients. In fact, for the patients with lumbar severe degeneration, their thoracic spine usually has similar degeneration, which often presents as thoracic kyphosis. Of course, we can predict their “ideal” lumbar segmental lordosis by the given PI. But in the case of the thoracic kyphosis (or other degenerative deformities), is this “ideal” segmental alignment really most suitable for these patients? After all, this question is an open issue that needs further investigation. For Anwar et al.’s [1] study, we think that it is necessary for the authors to analyze the SPeC in juveniles and adults, respectively, before they can come to a more accurate conclusion.