Reverse hybrid total hip arthroplasty.

Aims: This study aimed to evaluate implant survival of reverse hybrid total hip arthroplasty (THA) at medium-term follow-up. Patients and Methods: A consecutive series of 1082 THAs in 982 patients with mean follow-up of 7.9 years (5 to 11.3) is presented. Mean age was 69.2 years (21 to 94). Of these, 194 (17.9%) were in patients under 60 years, 663 (61.3%) in female patients and 348 (32.2%) performed by a trainee. Head size was 28 mm in 953 hips (88.1%) or 32 mm in 129 hips (11.9%). Survival analysis was performed and subgroups compared using log rank tests. Results: Ten-year survival (122 hips at risk) was 97.2% (95% confidence interval (CI) 95.77 to 98.11) for all-cause revision. There was no difference in survival by age (p = 0.50), gender (p = 0.78), head size (p = 0.63) or surgeon grade (p = 0.36). No acetabular components underwent revision for aseptic loosening in the entire series. Four (0.4%) aseptic stem failures occurred early at a mean of 2.5 years (0.6 to 4.8) and were associated with age under 60 years (p = 0.015). There was no difference in survival by gender (p = 0.12), head size (p = 0.43) or surgeon grade (p = 0.77) for stem revision. Conclusion: This is the largest reported study into reverse hybrid THA and it confirms successful outcomes, irrespective of age, gender, head size and surgeon grade. Cite this article: Bone Joint J 2018;100-B:1010-17.

Issues relating to long-term follow-up in hip arthroplasty surgery: a review of 598 cases at 7 years comparing 2 prostheses using revision rates, survival analysis, and patient-based measures.

We reviewed 598 cemented Charnley and Hi-nek total hip arthroplasties at 7 years. Data were obtained from general practitioners, hospital medical notes, microfilm, and patient questionnaires. Outcome measures were revision rates, survival analysis, 12-item Oxford Hip Score, and satisfaction ratings. There were 471 Charnley (79%) and 127 Hi-nek (21%) total hip arthroplasties; 139 deaths (23%) occurred, and 5 (<1%) were lost to follow-up. Characteristics of the Charnley and Hi-nek patient groups were similar, with more information missing for Charnley cases. Revision rates were Charnley, 37 (8%), and Hi-nek, 6 (5%) (not significant). Survival analysis revealed no difference between the 2 groups (P = .23). The patients' median Oxford Hip Score was low/good (19), slightly worse for the Hi-nek group (not significant). Taking all evidence together, neither implant was outperforming the other at 7 years.

Clinical and radiographic analysis of osteochondromas and growth disturbance in hereditary multiple exostoses.

Hereditary multiple exostoses (HME) is traditionally described as a skeletal dysplasia. However, the discovery that the EXT family of tumour suppressor genes are responsible for HME suggests that it is more appropriate to classify HME as a familial neoplastic trait. In a clinical and radiographic analysis of paired bone length and exostoses number and dimensions in a HME cohort, the local presence of osteochondromas was consistently associated with growth disturbance. In particular, an inverse correlation between osteochondroma size and relative bone length (p<0.01) was found. These data suggest that the growth retardation in HME may result from the local effects of enlarging osteochondromas rather than a skeletal dysplasia effect. This study provides the first clinical rationale for ablation of rapidly enlarging exostoses to reduce growth disturbance.

Primary human osteoblast proliferation and prostaglandin E2 release in response to mechanical strain in vitro.

The application of mechanical loads to bone cells in vitro has been found to generate variable responses, which may in part be due to the source of the cell used and the characteristics of the strain applied. The aim of this study was to establish a system for applying well-defined physiological levels of mechanical strain to a well-defined population of human osteoblast-like cells. Human bone-derived cells obtained from the greater trochanter of the femur during total hip arthroplasty for osteoarthritis were cultured in the presence of 10 nmol/L dexamethasone and 100 mumol/L L-ascorbate-2-phosphate. Replicates of cells from each patient were loaded on separate occasions using controlled cyclical strains of 4000 microstrain (mu epsilon) or less. Strain gauges recorded reliable, reproducible strains between 1000 and 6000 mu epsilon. To establish reproducibility, sequential explant cultures derived from two patients were studied. A consistent increase (p < 0.05) in proliferation between replicates and explants derived from one patient subjected to 1600 mu epsilon on separate occasions was observed. Cells derived from sequential explants of the second patient showed no consistent increase in proliferation between replicates and explants. Three of six patients showed a significant increase (p < 0.05) in PGE2 production after 5 h in response to stretch (4000 mu epsilon) in all replicates on separate occasions, whereas, in the other three populations of cells, no increase in PGE2 was measured in any of the replicates. These results show that the application of highly controlled strains causes a significant effect on human bone cells, but only in a proportion of subjects. The response is consistent between sequential explants derived from the same patient. The implications of this study are that human osteoblast-like cells do respond to physiological strain in vitro, although some cells are more strain sensitive than others.

Mutation screening of the EXT1 and EXT2 genes in patients with hereditary multiple exostoses.

Hereditary multiple exostoses (HME), the most frequent of all skeletal dysplasias, is an autosomal dominant disorder characterized by the presence of multiple exostoses localized mainly at the end of long bones. HME is genetically heterogeneous, with at least three loci, on 8q24.1 (EXT1), 11p11-p13 (EXT2), and 19p (EXT3). Both the EXT1 and EXT2 genes have been cloned recently and define a new family of potential tumor suppressor genes. This is the first study in which mutation screening has been performed for both the EXT1 and EXT2 genes prior to any linkage analysis. We have screened 17 probands with the HME phenotype, for alterations in all translated exons and flanking intronic sequences, in the EXT1 and EXT2 genes, by conformation-sensitive gel electrophoresis. We found the disease-causing mutation in 12 families (70%), 7 (41%) of which have EXT1 mutations and 5 (29%) EXT2 mutations. Together with the previously described 1-bp deletion in exon 6, which is present in 2 of our families, we report five new mutations in EXT1. Two are missense mutations in exon 2 (G339D and R340C), and the other three alterations (a nonsense mutation, a frameshift, and a splicing mutation) are likely to result in truncated nonfunctional proteins. Four new mutations are described in EXT2. A missense mutation (D227N) was found in 2 different families; the other three alterations (two nonsense mutations and one frameshift mutation) lead directly or indirectly to premature stop codons. The missense mutations in EXT1 and EXT2 may pinpoint crucial domains in both proteins and therefore give clues for the understanding of the pathophysiology of this skeletal disorder.

Streptococcus bovis-infected total hip arthroplasty.

The case of a 51-year-old man who underwent a total hip arthroplasty following failed AO screw fixation of a subcapital femoral neck fracture is reported. Infection of the prosthesis with Streptococcus bovis type 1 followed a febrile illness. Further investigation revealed an occult premalignant polyp in the proximal colon. Colonic neoplasia and S. bovis bacteremia are associated with endocarditis; however, S. bovis is a rare pathogen infecting joint prostheses and should raise the possibility of a gastrointestinal lesion.

Total hip replacement in renal transplant patients.

Of 1197 renal transplant recipients on the Oxford Transplant Programme, 25 (2%) needed arthroplasties for painful osteonecrosis of the hip. Nine of them had bilateral operations, giving a total of 34 primary total hip replacements (THR). The mean time from onset of symptoms to THR was 2.4 years and from transplantation to THR 5.1 years. The mean follow-up was 5.1 (1 to 14) years. THR relieved the pain in all the patients, but survival analysis indicated a lower survival rate than is usual for primary THR. There were eight major complications. One graft-related problem, early acute tubular necrosis, resolved rapidly after immediate treatment. One patient developed deep infection at 3.5 years after THR which settled with conservative treatment. Five hips developed aseptic loosening requiring revision arthroplasty at a mean of 8.8 years' follow-up. One patient had a non-fatal pulmonary embolism. THR is the treatment of choice for patients with painful osteonecrosis of the hip after renal transplant, but has higher rates of both early and late complications. Surgery should be performed in close association with a renal transplant unit.

Screening for abdominal aortic aneurysm: a single scan is enough.

A group of 223 men who were found to have a normal abdominal aortic diameter (less than 2.6 cm) at the age of 65 or 66 years when first examined by ultrasonography in 1988 was studied again 5 years later. Twenty-seven patients had died, none from confirmed aneurysm rupture, and repeat scans were obtained in 189 of the 196 survivors. A further patient was reassessed at laparotomy. Mean aortic diameter was unchanged during the intervening 5 years and 166 of 189 repeat scan measurements were within 3 mm of the original value. Only two patients were found to have an aortic diameter of 3 cm or more on rescanning. These results suggest that a single ultrasonographic examination at the age of 65 years can safely be used to exclude over 90 per cent of those examined from future risk of significant aneurysmal dilatation of the aorta, with important cost and organizational benefits for a population screening programme.