The learning curve with a new cephalomedullary femoral nail.

INTRODUCTION: The Cephalomedullary Nail (CMN) (Zimmer, Warsaw) was introduced in 2010 as part of a multicenter trial to evaluate its performance. At one year the CMN had results in keeping with other intramedullary devices with good union rates and low complication rates. In the second and third years of use an increased rate of implant failure was observed, towards the higher end of the 1-5% nail breakage rate seen in other studies. This study aims to evaluate if there any common features in this cohort of patients. MATERIALS AND METHODS: This is a retrospective cohort study looking at patients who underwent femoral fracture fixation using the cephalomedullary nail between January 2011 and June 2014. The primary outcome measure was implant failure; secondary outcomes were; fracture reduction and bisphosphonate use. RESULTS: 201 patients were included (135 female, 66 male) with an average age of 81 years. Ten (5%) nail breakages occurred in the study period at an average of 39 weeks (24-92); 9 were 125° nails 1 was a 130° nail and all fractured at the lag screw junction. CONCLUSIONS: Implant failure is a recognised complication of intramedullary nailing in cases of non-union. The increased rate of implant failure in our department required a change to a 130° CMN implant and a 3.2mm diameter guide wire for placement of the lag screw. We continue to monitor this difficult group of patients very closely.

Displaced intracapsular neck of femur fractures in the elderly: bipolar hemiarthroplasty may be the treatment of choice; a case control study.

Management of the mobile elderly patient who sustains an intra-capsular neck of femur fracture remains controversial. Current evidence is mixed as to whether total hip arthroplasty (THA), which confers higher surgical and dislocation risk, is significantly superior in function and in reduced rates of reoperation when compared to bipolar hemi-arthroplasty. A group of 110 patients with an intra-capsular NOF fracture who had undergone either THA or Bipolar hemi-arthroplasty and were still alive at the time of follow up were retrospectively identified and matched using the National Hip Fracture Database. Matching criteria included ASA, age, sex, pre-op mobility, pre-op AMTS and source of admission. Follow up was by postal questionnaire. Mean follow up was 24 months in both groups (Range; Bipolar 12-36 months, THA 12-38 months). There was no significant difference in pre-operative Tonnis grade, postoperative Oxford Hip Score (OHS) or Short Form 36 (SF-36) scores between the two groups. 12 dislocations in 5 patients occurred in the THA group and none in the bipolar group. 33/55 Bipolar patients were discharged to their own home compared to 35/55 in the THA group. None of the bipolar hemi-arthroplasties were revised to THA. Higher complication rates were experienced in the THA group with no increase in function.

The role of patient factors and implant position in squeaking of ceramic-on-ceramic total hip replacements.

We investigated factors that were thought to be associated with an increased incidence of squeaking of ceramic-on-ceramic total hip replacements. Between June 1997 and December 2008 the three senior authors implanted 2406 primary total hip replacements with a ceramic-on-ceramic bearing surface. The mean follow-up was 10.6 years. The diagnosis was primary osteoarthritis in each case, and no patient had undergone previous surgery to the hip. We identified 74 squeaking hips (73 patients) giving an incidence of 3.1% at a mean follow-up of 9.5 years (4.1 to 13.3). Taller, heavier and younger patients were significantly more likely to have hips that squeaked. Squeaking hips had a significantly higher range of post-operative internal (p = 0.001) and external rotation (p = 0.003) compared with silent hips. Patients with squeaking hips had significantly higher activity levels (p = 0.009). A squeaking hip was not associated with a significant difference in patient satisfaction (p = 0.24) or Harris hip score (p = 0.34). Four implant position factors enabled good prediction of squeaking. These were high acetabular component inclination, high femoral offset, lateralisation of the hip centre and either high or low acetabular component anteversion. This is the largest study to date to examine patient factors and implant position factors that predispose to squeaking of a ceramic-on-ceramic hip. The results suggest that factors which increase the mechanical forces across the hip joint and factors which increase the risk of neck-to-rim impingement, and therefore edge-loading, are those that predispose to squeaking.

Ceramic-on-ceramic bearing surface and risk of revision due to dislocation after primary total hip replacement.

Dislocation is a common reason for revision following total hip replacement. This study investigated the relationship between the bearing surface and the risk of revision due to dislocation. It was based on 110 239 primary total hip replacements with a diagnosis of osteoarthritis collected by the Australian Orthopaedic Association National Joint Replacement Registry between September 1999 and December 2007. A total of 862 (0.78%) were revised because of dislocation. Ceramic-on-ceramic bearing surfaces had a lower risk of requiring revision due to dislocation than did metal-on-polyethylene and ceramic-on-polyethylene surfaces, with a follow-up of up to seven years. However, ceramic-on-ceramic implants were more likely to have larger prosthetic heads and to have been implanted in younger patients. The size of the head of the femoral component and age are known to be independent predictors of dislocation. Therefore, the outcomes were stratified by the size of the head and age. There is a significantly higher rate of revision for dislocation in ceramic-on-ceramic bearing surfaces than in metal-on-polyethylene implants when smaller sizes (< or = 28 mm) of the head were used in younger patients (< 65 years) (hazard ratio = 1.53, p = 0.041) and also with larger (> 28 mm) and in older patients (> or = 65 years) (hazard ratio = 1.73, p = 0.016).

The effect of obesity on the mid-term survival and clinical outcome of cementless total hip replacement.

The outcome of total hip replacement (THR) is potentially affected by the body mass index (BMI) of the patient. We studied the outcome of 2026 consecutive primary cementless THRs performed for osteoarthritis. The mean follow-up was 6.3 years (0 to 11.71) and no patient was lost to follow-up for survival analysis. The patients were divided into two groups according to their BMI as follows: non-obese (BMI < 30 kg/m(2)) and obese (BMI > or = 30 kg/m(2)). The obese patient undergoing surgery was found to be significantly younger (p < 0.001). The log-rank test for equality of survival showed no difference in the mid-term survival (p = 0.552) with an estimated survival at 11 years of 95.2% (95% CI 92.5 to 98.0) in the non-obese and 96.7% (95% CI 94.9 to 98.5) in the obese groups. The clinical and radiological outcome was determined in a case-matched study performed on 134 obese individuals closely matched with 134 non-obese controls. The non-obese group was found to have a significantly higher post-operative Harris hip score (p < 0.001) and an increased range of movement, but overall satisfaction with surgery was comparable with that of the obese patients. Radiological analysis of the acetabular and femoral components showed no significant differences with regard to radiolucent lines, osteolysis, ingrowth of the femoral component, the acetabular inclination angle or alignment of the femoral component. Our results suggest that the survival of cementless THR is not adversely affected by obesity. Obese patients can therefore be counselled that despite a lower clinical score, they should expect to be satisfied with the result of their THR with a mid-term survival rate equivalent to that of non-obese patients.

The impact of obesity on the mid-term outcome of cementless total knee replacement.

We evaluated 535 consecutive primary cementless total knee replacements (TKR). The mean follow-up was 9.2 years (0.3 to 12.9) and information on implant survival was available for all patients. Patients were divided into two groups: 153 obese patients (BMI > or = 30) and 382 non-obese (BMI < 30). A case-matched study was performed on the clinical and radiological outcome, comparing 50 knees in each group. We found significantly lower mean improvements in the clinical score (p = 0.044) and lower post-operative total clinical scores in the obese group (p = 0.041). There was no difference in the rate of radiological osteolysis or lucent lines, and no difference in alignment. Log rank test for survival showed no significant differences between the groups (p = 0.167), with a ten-year survival rate of 96.4% (95% confidence interval (CI) 92 to 99) in the obese and 98% (95% CI 96 to 99) in the non-obese. The mid-term survival of TKR in the obese and the non-obese are comparable, but obesity appears to have a negative effect on the clinical outcome. However, good results and high patient satisfaction are still to be expected, and it would seem unreasonable to deny patients a TKR simply on the basis of a BMI indicating obesity.

The triplanar chevron osteotomy.

BACKGROUND: The chevron osteotomy is a widely used procedure in the surgical treatment of symptomatic mild to moderate hallux valgus deformity. Biplanar chevron osteotomy has previously been described to correct the deformity in two planes. There are patients in whom the ideal procedure would include lateral translation of the head (to correct the hallux valgus and intermetatarsal angles), angular correction of the abnormal lateral inclination of the joint surface and, finally, plantar displacement of the head fragment without significantly shortening the first ray as might the Youngswick-Austin procedure. METHOD: This paper describes a variation of the chevron osteotomy. CONCLUSION: We believe that this osteotomy achieves correction of the hallux valgus deformity in three planes.

The transverse acetabular ligament may be used to align the acetabular cup in total hip arthroplasty.

Accurate positioning of the acetabular component in total hip arthroplasty is essential to minimise the risk of dislocation and preserve the range of movement of the hip. It also affects polyethylene wear and the rate of osteolysis. Although there are many tools available to the surgeon to aid placement of the acetabular component, errors still occur, especially in version. We conducted a study of 14 cadaveric hips to investigate whether the transverse acetabular ligament can be used to align implanted cups with the correct degree of anteversion. Radiographic measurement revealed that all of the implanted cups were found to lie within the 'safe zone' for anteversion, when aligned with the ligament.

The misuse of 'no significant difference' in British orthopaedic literature.

INTRODUCTION: Many studies published in medical journals do not consider the statistical power required to detect a meaningful difference between study groups. As a result, these studies are often underpowered: the sample size may not be large enough to pick up a statistically significant difference (or other effect of interest) of a given size between the study groups. Therefore, the conclusion that there is no statistically significant difference between groups cannot be made unless a study has been shown to have sufficient power. The aim of this study was to establish the prevalence of negative studies with inadequate statistical power in British journals to which orthopaedic surgeons regularly submit. MATERIALS AND METHODS: We assessed all papers in the last consecutive six issues prior to the start of the study (April 2005) in The Journal of Bone and Joint Surgery (British), Injury, and Annals of the Royal College of Surgeons of England. We sought published evidence that a power analysis had been performed in association with the main hypothesis of the paper. RESULTS: There were a total of 170 papers in which a statistical comparison of two or more groups was undertaken. Of these 170 papers, 49 (28.8%) stated as their primary conclusion that there was no statistically significant difference between the groups studied. Of these 49 papers, only 3 (6.1%) had performed a power analysis demonstrating adequate sample size. CONCLUSIONS: These results demonstrate that the majority of negative studies in the British orthopaedic literature that we have looked at have not performed the statistical analysis necessary to reach their stated conclusions. In order to remedy this, we recommend that the journals sampled include the following guidance in their instructions to authors: the statement 'no statistically significant difference was found between study groups' should be accompanied by the results of a power analysis.

The Kent hip prosthesis: an evaluation of 145 prostheses after a mean of 5.1 years.

The Kent hip is a distally-locked femoral stem which was developed to address severe proximal bone loss, severe bony deformity and peri-prosthetic fracture. We reviewed the results of 145 consecutive Kent hips implanted into 141 patients between 1987 and 2000. The indications for implantation were aseptic loosening (75 hips), septic loosening (two), peri-prosthetic and prosthetic fracture (37), severe bony deformity (24), and fracture through a proximal femoral metastasis (seven). The median time to full weight-bearing after surgery was two days and the mean length of follow-up was 5.1 years (2 to 15). Further revisions were required for 13 femoral stems. With removal of the stem for any reason as an end-point, the cumulative survival at five, ten and 15 years was 93%, 89% and 77%, respectively. In patients aged>or=70 years, the cumulative survival at 15 years was 92%, compared with 68% in those aged<70 years. Because of these findings, we recommend the use of interlocking stems in patients aged>or=70 years, particularly in those with a peri-prosthetic fracture, for whom alternative methods are limited. Outcome scores and survival data, compared with other systems, indicate that the Kent hip should be used with caution in younger patients.

The detection of rubella-specific IgM by an immunosorbent assay with solid-phase attachment of red cells (SPARC).

An immunosorbent assay using solid-phase attachment of red cells (SPARC) was used for the detection of rubella-specific IgM. The method is described and the results compared with those obtained by the IgM antibody capture radioimmunoassay (MACRIA). One hundred and ninety-nine sera were investigated for the presence of rubella-specific IgM and only one discrepant result occurred, namely a false positive obtained by MACRIA in a patient with infectious mononucleosis. Rheumatoid factor, heterophile antibody, and rubella-specific IgG did not interfere with the results obtained by the SPARC technique. Advantages of the SPARC technique include the case and lack of expense of testing large numbers of sera, the small volume of sample required and the fact that pretreatment of serum is not necessary.

Combined cytotoxic and progestogen therapy for advanced breast cancer.

Sixty-nine patients with advanced breast cancer treated with cytotoxic chemotherapy were randomized to receive concomitantly either norethisterone acetate (progestogen group) or a placebo (placebo group). Objective responses were seen in 53% of patients in the progestogen group and 61% of patients in the placebo group. The median duration of response was the same for both groups (38 weeks). Three out of ten patients in the placebo group, who received subsequently the progestogen on relapse, had a further objective regression. The overall survival in the two groups was similar, although in a sub-group of patients who had operable tumors, but a subsequent short disease-free interval, survival was significantly better in the placebo group. There was less myelosuppression in the progestogen group, who were able to receive higher doses of cytotoxic drugs. Less nausea and vomiting occurred in the progestogen group, but subjective side effects were similar. It is concluded that there is no advantage therapeutically in combining cytotoxic chemotherapy and progestogen therapy and, in some patients, better results are obtained using the two treatments sequentially.

The metabolism of lithocholic acid-3alpha-sulfate by human intestinal microflora.

Lithocholic acid-3alpha-sulfate is metabolized by human intestinal microflora to nonpolar metabolites which have been partially purified by Sephadex LH-20 chromatography. These metabolites were characterized by thin layer and gas liquid chromatography as well as combined gas liquid chromatography-mass spectrometry. The chromatographic properties of one of the metabolites are consistent with those described for a delta2- or delta3-cholenate. The formation of cholenates by the microflora may represent a retoxification of the sulfate ester of lithocholic acid.

Isolation and purification of lithocholic acid metabolites produced by the intestinal microflora.

Lithocholic acid metabolites produced by the intestinal microflora of rats can be isolated from other endogenous lipids using Sephadex LH-20 column chromatography. Analyses of individual metabolites collected from the column by silica gel coated glass fiber paper chromatography result in the resolution of epimeric 3-hydroxy derivatives. In addition, glass fiber paper chromatography is more sensitive and requires less development time than conventional glass-coated thin-layer plates. Further confirmation of the identity of metabolites is achieved by gas-liquid chromatography, which separates both methyl and ethyl esters of lithocholic and isolithocholic acids.