INTRODUCTION

Studies have suggested that there is a reduction in head-neck-ratio (HNR) associated with MoMHRA. A reduction in HNR at operation would decrease range of movement and increase impingement risk. Impingement could lead to 20 edge loading, increasing wear. Serum ion levels of Chromium (Cr) and Cobalt (Co) are surrogate markers of wear. Although acetabular component orientation has been shown to contribute to wear and PT development, the role of a decrease in HNR has only been highlighted in PT development. This study aimed to measure changes in HNR that occur at resurfacing and determine any gender- and component size-specific differences. In addition it aimed to determine whether changes in HNR could be associated with increased wear.

INTRODUCTION

Although simulation studies have shown superior wear properties of metal-on-metal articulations, increased concern exists regarding the excess in-vivo wear of a small number of Metal-on-Metal-Hip-Resurfacing (MoMHRA) implants. Serum ion levels of Chromium (Cr) and Cobalt (Co) are surrogate markers of wear. Risk factors associated with increased wear include female gender, small components, dysplasia, cup orientation outside safe zone and femoral head downsize during surgery with an associated decrease in Head-Neck-Ratio (HNR). However, these factors are interlinked. This study aims to identify the factors that are most important for subsequent wear of MoMHRA, by performing a multivariate analysis.

INTRODUCTION

The introduction of hard-on-hard bearings and the consequences of increased wear due to edge-loading have renewed interest in the importance of acetabular component orientation for implant survival and functional outcome following hip arthroplasty. Some studies have shown increased dislocation risk when the cup is mal-oriented which has led to the identification of a safe-zone1. The aims of this prospective, multi-centered study of primary total hip arthroplasty (THA) were to: 1. Identify factors that influence cup orientation and 2. Describe the effect of cup orientation on clinical outcome.

Patients with hip fracture are at high risk of venous thromboembolism (VTE). Chemical thromboprophylaxis with low molecular weight heparin (LMWH) is associated with a risk of major bleeding in certain patient groups, such as those with renal failure. In these patients, unfractionated heparin should be used. Our aim was to determine the practice of VTE risk assessment in patients admitted with hip fracture against the national guidance, which states that all should have VTE risk assessment on admission. We also assessed the impact of introducing the VTE risk assessment form on prescribing practice of chemical thromboprophylaxis in patients with renal failure.

Prospective audit of patients of 50 patients admitted with hip fracture from 4/8/10 with re-audit of 50 patients admitted from 17/2/2011 after introducing the VTE risk assessment form into the hip fracture admissions proforma. Retrospective analysis was undertaken to determine chemical thromboprophylaxis prescribing in patients with eGFR <30ml/min/1.73m².

Patient demographics were comparable in both audit loops, with the mean age being equal (84 years) and an equal majority of female patients (76%). There were similar numbers of patients with eGFR <30ml/min/1.73m² in both audit loops with 8% (n=4) in the initial audit, and 10% (n=5) in the re-audit. Frequency of VTE risk assessment significantly increased from 16% to 86% after including the VTE risk assessment form in the hip fracture proforma (p<0.0001). Despite this, there was no significant reduction in prescribing of LMWH in patients with renal failure with eGFR <30ml/min/1.73m², (P=0.52).

Documentation of VTE risk assessment in patients admitted with hip fracture can be improved by simple measures such as inclusion of the VTE risk assessment form in the admissions proforma. However, this did not result in a reduction of LMWH prescribed in patients with significant renal failure and risk of major bleeding.

Cognitive impairment is common in patients with hip fracture both on admission and may develop later on. Reduced cognitive function is a risk factor for development of delirium, correlates with poor rehabilitation, and is an independent predictor of increased mortality. Despite its commonplace and potential for serious morbidity, cognitive dysfunction is often poorly assessed & diagnosed.

Our aims were to 1) assess the practice of cognitive assessment on admission for hip fracture patients according to local guidelines and 2) ascertain whether it can be improved by the formal introduction of Abbreviated Mental Test Score (AMTS) & Clock Drawing Test (CDT) in the hip fracture admission proforma.

A prospective audit was undertaken of cognitive assessment by either AMTS or CDT for 50 consecutive patients admitted with hip fracture from 4/8/2010. Subsequently, the hip fracture admission proforma was amended to include both the AMTS & CDT. A re-audit was performed on 50 consecutive patients admitted from 17/2/2011 to determine the change in practice.

Patient demographics were comparable in both audit loops, with the mean age being equal (84 years) and an equal majority of female patients (76%). Cognitive assessment by either AMTS or CDT significant increased from 28% (n=14) to 86% (n=43) in the re-audit (p<0.0001). All AMTS were completed in accordance with instructions, whereas almost half of CDTs were incompletely or incorrectly filled out (45%).

The assessment of cognitive function can be greatly improved by inclusion of both the AMTS & CDT to the hip fracture admission proforma, allowing the most appropriate multi-disciplinary care to be planned for the patient. Whilst both CDT and AMTS are good screening tools for cognitive impairment, many are unfamiliar with CDT & more training is needed.

Stem geometry is known to influence the outcome in THA; however it is unknown whether the material properties, stiffness in particular can influence the stem stability and outcome. The aim of this study was to measure the influence of stem material properties on micromotion and migration using Roentgen Stereophotogrammetric Analysis (RSA) system.

41 patients were implanted with a collarless polished tapered (CPT) femoral stem (Zimmer, Warsaw, Indiana), which was made of either cobalt-chromium (CoCr) (n=21) or stainless steel (n=20). RSA was used to measure dynamically inducible micromotion (DIMM: difference in stem position in going from double-leg stance (DLS) to single leg stance (SLS)), prosthesis bending (difference in the head-tip distance when going from DLS to SLS), and mean migration of the head, tip and the cement restrictor. DIMM and bending were measured at 3 months, migration at 6, 12 and 24 months. All analyses were carried out using SPSS for windows (v.15.0.0, Chicago. IL, USA). Results were reported as mean ± 95% confidence interval (CI) and regarded as significant when p < 0.05.

Preliminary analysis showed that total head DIMM was significantly (p = 0.02) greater for CoCr (0.97mm ± 0.6mm) than stainless steel (0.27mm ± 0.6mm). The mean stem bending for CoCr was 0.08mm (± 0.06mm) and for stainless steel 0.15mm (± 0.06mm) (p =0.77). Both implants heads migrated posteriorly, medially and distally. The mean subsidence for the cobalt-chromium and stainless steel stems was 1.02mm (± 0.19mm) (p < 0.001) and 1.12mm (± 0.34mm) (p=0.001) (p= 0.07) at 24 months.

It was interesting to note that the dynamically induced micromotion was greater for the stiffer stem, however there were no differences in terms of overall migration, indicating that survival (in terms of loosening) should be the similar for both steel and CoCr versions of this implant.

INTRODUCTION

The risk of dislocation in large diameter metal on metal hip replacement is significantly lower than in standard THR. This is due to the increased primary arc, increased jump distance and possibly a suction effect. Our unit has performed over 1500 of these cases with an overall revision rate of <1%. We report a case series of dislocations in 5 large diameter metal on metal hips undertaken at our unit.

Femoral stem varus has been associated with poorer results. We report the incidence of varus/valgus malalignment of the Exeter polished, double taper design in a multicentre prospective study. The surgical outcomes at a minimum of five year and complication rates are also reported.

A multicentre prospective study of 987 total hip replacements was undertaken to investigate whether there is an association between surgical outcome and femoral stem malalignment. The primary outcome measure was the change in the Oxford hip score (OHS) at five years. Secondary outcomes included the rate of dislocation and revision.

The incidence of varus and valgus malignment were 7.1% and 2.6% respectively. There was no significant difference in OHS between neutral and malaligned femoral stems at 5 years (neutral, mean = 40.2; varus, mean 39.3, p = 0.465; valgus, mean = 40.9, p = 0.605). There was no significant difference in dislocation rate between the groups (p = 0.66). There was also no significant difference in revision rate (p = 0.34).

This study provides evidence that the Exeter stem is extremely tolerant of varus and valgus malalignment, both in terms of outcome and complication rate.

Aim

To determine the outcome, the need for revision surgery, quality of life (QOL) of patients and the financial implications of instability following successful closed reduction of dislocation after primary total hip arthroplasty (THA).

Introduction: Metal-on-metal-hip-resurfacing-arthroplasty (MoMHRA) has been associated with the development of inflammatory pseudotumours(IP), especially in females. IPs have been linked to wear debris, which can be related to metal-ion blood levels. Acetabular component position has been shown to influence wear. We have identified an optimum component orientation minimising IP risk around an inclination/anteversion of 40°/20°±10°. Our aim was to see if this optimal position results in lower metal ions and to identify the boundary of an optimal placement zone for low wear.

Methods: A cohort of 104 patients(60M:44F) with unilateral MoMHRA was studied. Blood tests were obtained at a mean follow up of 3.9 years and serum Co/Cr levels were measured(ICPMS). High metal ion concentrations were defined as Co> 4.1ppb and Cr> 5.2ppb. Radiographic cup inclination/anteversion were measured using EBRA. The differences in ion levels between different orientation zones were investigated. Three orientation zones were defined centered on 40°/20°: Z1-within ±5°, Z2-outside ±5°/within ±10° and Z3-within ±10°.

Results: There was a wide range of cup placements. Females had significantly (p< 0.001) smaller components(mean:51, 44–60) than males(mean: 56, 52–64). Cr levels, but not Co, were higher in females(p=0.002) and those with small femoral components(< 50mm, p =0.03). Patients with cups within Z1 (n=13) had significantly lower Co(p=0.005) and Cr(p=0.001). Males with cups within Z3(n=27) had lower ion levels in comparison to those outside, which were significantly lower for Co(p=0.049) but not Cr(p=0.084). Females had similar ion levels within and out of Z3(Cr/Co: p=0.83/0.84). Co levels were significantly lower in Z1(n=13) in comparison to Z2(n=33)(p=0.048) but Cr levels were not different (p=0.06).

Discussion: MoMHRA cups placed within ±5° of the optimum(40°/20°) had significantly lower metal ions indicating lower wear within this narrow zone. This safe zone, could extend to ±10° for males only. The narrower safe zone coupled with smaller components implanted are possible factors contributing to the increased IP incidence seen in females.

Introduction: Metal on metal hip resurfacing arthroplasty-induced pseudotumours are a serious complication, which occur in 1.8% of patients who undergo this procedure in our institution. The aim of this study was to measure the 3D in vivo wear on the surface of resurfacing components revised for pseudotumour, compared to a control group.

Method: Thirty-six hip resurfacing implants were divided into two groups; 18 patients with a clinical and histopathological diagnosis of pseudotumour and 18 controls (revised for femoral neck fracture and infection). Three dimensional contactless metrology (Redlux^™ Ltd) was used to scan the surface of the femoral and acetabular components, to a resolution of 20 nanometers. The location, depth and area of the wear scar were determined for each component. A separate blinded analysis to determine the presence of absence of impingement was performed by one of the authors.

Results: The volumetric wear rate for femoral component of the pseudotumour group was 3.29 mm3/yr (SD5.7) and 0.79 mm3/yr (SD1.2) for the control group (p=0.005). In the pseudotumour group, the volumetric wear rate of the acetabular component was 2.5 mm3/yr (SD6.9) compared to 0.36 mm3/yr (SD0.80) for the control group (p=0.008). Edge-wear was detected in 89% of acetabular components in the pseudotumour group and 21% of those in the control group (p=0.01). Anterior or posterior edge-wear, consistent with impingement was present on the femoral components of 73% of patients in the pseudotumour group and 22% in the control group (p=0.01).

Discussion: This work demonstrates that implants revised for pseudotumour have significantly higher volumetric wear rates than controls. They also have a significantly higher incidence of edge-wear than controls. We suggest that a significant proportion of pseudotumours are associated with high concentrations of metal wear debris; however a minority may result from a hypersensitivity reaction to metal ions.

Introduction: The use of highly cross-linked polyethylene (HXLPE) is now commonplace for total hip arthroplasty, however there is no long-term data to support its use. Hip simulator studies suggest that the wear rate of some types of HXLPE is ten times less than conventional polyethylene (UHMWPE). The outcomes of hip simulator studies are not always reproduced in vivo and there is some evidence that HXLPE wear may increase between 5 and 7 years.

Method: A prospective double blind randomised control trial was conducted using Radiostereometric Analysis (RSA). Fifty-four subjects were randomised to receive hip replacements with either UHMWPE liners or HXLPE liners. All subjects received a cemented CPT stem and uncemented Trilogy acetabular component (Zimmer, Warsaw, IN, USA). The 3D penetration of the head into the socket was determined to a minimum of 7 years.

Results: The total liner penetration was significantly different at 7 years (p=0.005) with values of 0.33 mm (SE 0.05 mm) for the HXLPE group and 0.55 mm (SE 0.05 mm) for the UHMWPE group. The steady state wear rate from 1 year onwards was significantly lower for HXLPE (0.005 mm/yr, SE 0.007 mm/yr) than for UHMWPE (0.037 mm/yr, SE 0.009 mm/yr) (p=0.007). The direction of wear was supero-lateral.

Discussion: We have previously demonstrated that the penetration in the first year is creep-dominated, from one year onwards the majority of penetration is probably due to wear. This study confirms the predictions from hip simulator studies which suggest that the wear rate of this HXLPE approaches that of metal-on-metal and ceramic-on-ceramic articulations. HXLPE may have the potential to reduce the need of revision surgery, due to wear debris induced osteolysis. It may also enable surgeons to use larger couples, thus reducing the risk of impingement and dislocation.

Introduction: Metal on metal hip resurfacing arthroplasty(MoMHRA) is an alternative option to THR in the treatment of young adults with OA. A recognised MoMHRA complication is the development of an inflammatory pseudotumour(IP). Diagnosis is made with the aid of US and/or MRI. To-date, no radiographic indication of the presence of IP has been identified. Neck thinning is a recognised phenomenon in MoMHRA hips not associated with any adverse clinical events. Its pathogenesis is considered multi-factorial. Our aim was to establish whether excessive neck narrowing is associated with the presence of a pseudotumour.

Methods: Twenty-seven hips (26 patients) with IP confirmed clinically, radiologically, intra-operatively and histologically were matched for sex, age, pre-operative diagnosis, component size and follow-up with an asymptomatic MoMHRA cohort (Control n=60). For all patients, prosthesis-neck-ratio(PNR) was measured on plain AP pelvic radiographs post-operatively and at follow-up as previously described and validated.

Results: All IP patients (4M:23F) and all (12M:48F) but two controls had a posterior approach at the time of MoMHRA. Post-operatively, there was no difference in the PNR between the two groups (p=0.19). At an average follow up of 3.5 years (range:0.7–8.3), IP patients(mean 1.26, 1.10–1.79) had a significantly higher (p< 0.0001) PNR in comparison to their controls(mean 1.14, 1.03–1.35). Greater neck narrowing occurred in both genders. IP necks had narrowed by an average of 8% (range:3–23). The degree of neck narrowing was correlated with length of survival of implant (p=0.001).

Discussion: This study shows a strong association between IP and neck narrowing. Processes such as impingement and increased wear are considered to be involved in the pathogenesis of both IP and neck narrowing. Furthermore, the presence of an IP, could lead to altered vascularity via a mass effect and further contribute to neck narrowing. Neck narrowing in symptomatic MOMHRA patients should alert surgeons of the possible presence of IP.

Introduction: The assessment of quality in the provision of healthcare is one of the core features of the National Health Service in the 21st Century. From April 2009 Patient Reported Outcome Measure (PROM) data are being collected for the Department of Health for elective hip and knee arthroplasty using generic and disease specific measures of health status. The perceived uses of these data may be for research, assessment of procedural outcome, measures of health inequalities and to aid commissioning groups in selecting their secondary care providers. Foot and ankle surgery covers a wide spectrum of operative procedures with patient responses less predictable than with major joint arthroplasty. We report the use of a sixteen point satisfaction-based questionnaire in order to investigate the nature of patient outcome after the processes of foot and ankle surgery.

Methods: A prospective series of 100 two-part Visual Analogue Scale (VAS) questionnaires was distributed to patients undergoing elective foot and ankle surgery at the Northern General Hospital under the care of four foot and ankle surgeons over a three-month period. The questionnaires were numbered to allow patient anonymity. The first part of nine questions enquired about pre-operative preparation and information and was distributed before surgery. The second part of seven questions, distributed at the first post-operative clinic sought to investigate their hospital and operative experience. Free text comments were requested in addition to the VAS responses, which were expressed as percentages.

Results: 97% of part one and 85% of part two questionnaires were returned completed. 82% had both parts completed and matched. The day case to inpatient ratio was 55: 45. For part one, all clinically related questions scored more than 90% satisfaction, with only two scores for administration-based questions falling below this level. For part two, satisfaction for clinical questions again scored more than 90% and overall, all scored more than 80% satisfaction. Only 23% of pre-operative and 28% of post-operative questionnaires were returned with free-text comments.

Conclusions: A simple patient satisfaction-based questionnaire may be as useful as existing non-validated generic scoring systems used in foot and ankle surgery when assessing quality in the health service, particularly where regional demographics or referral patterns may be important factors influencing patient outcomes. Active dialogue with the surgical colleges and Department of Health should be pursued to avoid inappropriate outcome measures being imposed in foot and ankle surgery.

Metal on metal hip resurfacing (MMHR) is a popular procedure for the treatment of osteoarthritis in young patients. Several centres have observed masses, arising from around these devices, we call these inflammatory pseudotumours. They are locally invasive and may cause massive soft tissue destruction. The aim of this study was to determine the incidence and risk factors for pseudotumours that are serious enough to require revision surgery.

In out unit, 1,419 MMHRs were performed between June 1999 and November 2008. All revisions were identified, including all cases revised for pseudotumour. Pseudotumour diagnosis was made by histological examination of samples from revision. A Kaplan-Meier survival analysis was performed, Cox regression analysis was used to estimate the independent effects of different factors.

The revision rate for pseudotumour increased with time and was 4% (95% CI: 2.2% to 5.8%) at eight years. Female gender was a strong risk factor: at eight years the revision rate for pseudotumours in men was 0.5% (95% CI 0% to 1.1%), in women over 40 it was 6% (95% CI 2.3% to 10.1%) and in women under 40 it was 25% (95% CI 7.3% to 42.9%) (p< 0.001). Other factors associated with an increase in revision rate were, small components (p=0.003) and dysplasia (p=0.019), whereas implant type was not (p=0.156).

We recommend that resurfacings are undertaken with caution in women, especially those younger than 40 years of age, but they remain a good option in men. Further work is required to understand the patho-aetiology of pseudotumours so that this severe complication can be avoided.

Introduction: Pseudotumours (soft-tissue masses relating to the hip joint) following metal-on-metal hip resurfacing arthroplasty (MoMHRA) have been associated with elevated serum and hip aspirate metal ion levels, suggesting that pseudotumours occur when there is increased wear. This study aimed to quantify in vivo wear of implants revised for pseudotumours and a control group of implants revised for other reasons of failure.

Methods: A total of 30 contemporary MoMHRA implants in two groups were investigated in this Institutional Review Board approved study:

8 MoMHRA implants revised due to pseudotumour;

The linear wear of retrieved implants was measured using a Taylor-Hobson Roundness machine. The average linear wear rate was defined as the maximum linear wear depth divided by the duration of the implant in vivo.

Results: In comparison with the non-pseudotumour implant group, the pseudotumour implant group was associated with:

significantly higher median linear wear rate of the femoral component: 8.1um/year (range 2.75–25.4um/year) vs. 1.79um/year (range 0.82–4.15um/year), p=0.002; and

Similarly, differences were also measured in absolute wear values. The median absolute linear wear was significantly higher in the pseudotumour implant group:

21.05um (range 2.74–164.80um) vs. 4.44um (range 1.50–8.80um) for the femoral component, p=0.005; and

Wear on the acetabular cup components in the pseudotumour group always involved the edge, indicating edge-loading of the bearing. In contrast, edge-loading was observed in only one acetabular component in the non-pseudotumour group of implants. The deepest wear was observed well within the bearing surface for the rest of the non-pseudotumour group. The difference in the incidence of edge-loading between the two groups was statistically significant (Fisher’s exact test, p=0.03).

Discussion: Significantly greater linear wear rates of the MoMHRA implants revised due to pseudotumour support the in vivo elevated metal ion concentrations in patients with pseudotumours. This study provides the first direct evidence to confirm that pseudotumour is associated with increased wear at the MoM articulation. Furthermore, edge-loading with the loss of fluid film lubrication may be the dominant wear generation mechanism in patients with pseudotumour.

Introduction: Metal on metal hip resurfacing arthroplasty-induced pseudotumours are a serious complication, which occur in 4% of patients who undergo this procedure. The aim of this study was to measure the 3D in vivo wear on the surface of resurfacing components revised for pseudotumour, compared to a control group.

Method: Thirty-nine hip resurfacing implants were examined; these were sourced from our institutions prosthesis retrieval bank. They were divided into two groups; 22 patients with a clinical and histopathological diagnosis of pseudotumour and 17 controls. Patient demographics and time to revision were known. Three dimensional contactless metrology (Redlux™ Ltd) was used to scan the surface of the femoral and acetabular components, to a resolution of 20 nanometers. The location, depth and area of the wear scar was determined for each component. Volumetric wear was determined, along with the presence of absence of edge-loading. A separate blinded analysis to determine the presence of absence of impingement was performed by one of the authors. ANOVA was used to test for differences in wear and Fishers Exact test was used to compare the incidence of edge-loading between the groups.

Results: The volumetric wear rate for femoral component of the pseudotumour group was 4.7mm3/yr (SD3.5) and 1.7 mm3/yr (SD1.5) for the control group (p=0.03). In the pseudotumour group, the volumetric wear rate of the acetabular component was 3.5 mm3/yr (SD3.6) compared to 0.02 mm3/yr (SD0.07) for the control group (p=0.01). Edge-loading was detected in 74% of acetabular components in the pseudotumour group and 22% of those in the control group (p=0.01). Anterior or posterior edge-loading, consistent with impingement was present on the femoral components of 73% of patients in the pseudotumour group and 22% in the control group (p=0.01).

Discussion: This work demonstrates that implants revised for pseudotumour have significantly higher volumetric wear rates than controls. They also have a significantly higher incidence of edge-loading and impingement than controls. Edge-loading significantly increases wear. We suggest that pseudotumours are caused by high concentrations of metal wear debris, which have been shown to have a toxic effect on osteocytes and macrophages. This is the one of the first studies to demonstrate a clear link between pseudotumours and increased bearing surface wear. It is also the first to demonstrate that edge-loading, due to impingement, occurs in a significant number of patients who develop this condition. Improved implantation techniques and resurfacing designs may help avoid this serious complication of hip resurfacing.

Introduction: The use of second generation highly cross-linked polyethylene (HXLPE) is now commonplace for total hip arthroplasty, however there is no long-term data to support its use. Hip simulator studies suggest that the wear rate of HXLPE is ten times less than conventional polyethylene (UHMWPE). The outcomes of hip simulator studies are not always reproducible in vivo. Long term clinical data is required, as there is emerging clinical data, which suggests that some types of second generation HXLPE may have increased wear after 5 years.

Method: A prospective double blind randomised control trial was conducted using Radiostereometric analysis (RSA). Fifty-four subjects were randomised to receive hip replacements with either UHMWPE liners or HXLPE liners. All subjects received a cemented CPT stem and uncemented Trilogy acetabular component (Zimmer, Warsaw, IN, USA). The 3D penetration of the head into the socket was determined to a minimum of 7 years.

Results: The total liner penetration was significantly different at 7 years (p=0.01) with values of 0.33mm (SD 0.17mm) for the HXLPE group and 0.51mm (SD 0.14mm) for the UHMWPE group. The steady state wear rate from 1 year onwards was significantly lower for HXLPE (0.003 mm/yr, SD 0.04 mm/yr) than for UHMWPE (0.03 mm/yr, SD 0.03 mm/yr) (p=0.01). The direction of wear was in the antero-medial direction in both groups.

Conclusion: We have previously demonstrated that the penetration in the first year is creep-dominated, from one year onwards the majority of penetration is due to wear. The wear rate of this second generation HXLPE approaches that of metal on metal bearings. Second-generation HXLPE may have the potential to reduce the risk of revision surgery, due to wear debris induced osteolysis.

Introduction: Metal-on-metal hip resurfacing arthroplasty (MoMHRA) has gained popularity as an alternative to THR for younger patients with osteoarthritis. A growing concern has been the association of MoMHRA with the development of inflammatory pseudotumours (IP), especially in women. These have been linked to metal-on-metal wear, which can be related to metal ion concentrations. Elevated metal wear debris levels may result from impingement, rim contact and edge loading. Head-neck ratio (HNR) is a predetermining factor for range of movement and impingement. Neck thinning is a recognised phenomenon post-MoMHRA and we have found an association of IP with increased neck thinning based on a case control study. Our aims were to identify HNR changes a hip undergoes when resurfaced and at follow up; and whether greater neck thinning at follow-up could be associated with the presence of elevated metal ions.

Methods: A cohort of 91 patients (57M:34F) with unilateral MoMHRAs were included in this study. Blood tests were obtained at a mean follow up of 3.9 years (range 1.7–7 years) and serum (Co:Cr) ion levels were measured (ICPMS). High metal ion concentrations were defined as Co> 4.1ppb and Cr> 5.2ppb. For all patients, head-neck ratio (HNR) was measured on plain anterio-posterior pelvic radiographs pre-operatively, immediately post-operatively and at follow-up.

Results: Female patients had significantly bigger HNR pre-op (mean=1.35, range:1.22–1.64) compared to males(mean=1.22, range:1.05–1.38) (p< 0.01). Immediately post-op, female HNRs (mean: 1.26, range: 1.14–1.34) were not different to male patients(mean=1.24, range=1.11–1.38) (p=0.11). At follow-up HNR was once again significantly bigger (p< 0.01) in females (mean=1.35, range: 1.21–1.49), compare to males (mean=1.27, range:1.11–1.38). HNR alterations with operation (p=0.00) and at follow-up (p< 0.01) were significantly bigger in female patients. Furthermore, there was a significant correlation between high ion levels and HNR change at follow-up for both Co (p=0.02) and Cr (p< 0.01).

Conclusion: This study identified gender-specific changes in HNR that resurfaced hips undergo, not previously documented. Female hips have greater HNR pre-operatively, compared to male hips, and appear to be biomechanically disadvantaged when resurfaced. A decrease in HNR with resurfacing could result in impingement and lead to processes, known to be more prevalent in females, such as neck thinning, increased wear and IP development. In addition, we highlight a correlation between high ion levels and greater neck thinning at follow-up. Increased neck thinning in symptomatic MoMHRA hips could be secondary to increased wear and should be investigated further radiologically for the presence of IP.

From 2004–2006, in an attempt to reduce the waiting time for patients listed for total knee and total hip arthroplasty at Cardiff and Vale NHS Trust, 156 total hip replacements (THRs) were performed by Swedish Orthopaedic surgeons at an NHS treatment centre in England.

All patients were contacted and invited to a review appointment with a Consultant specialising in hip and revision hip replacement. Oxford Hip Scores and clinical and radiographic evaluation were performed. Patients who declined an appointment were sent a postal questionnaire. Radiographs were analysed for component position, radiolucent lines, medial floor breach, leg length discrepancy.

One hundred and thirteen hips were reviewed at a mean 23 month follow-up. The mean Oxford score was 26. Mean age at surgery was 69. Cemented THR was performed in 104 hips; hybrid in 7; cementless in 2. The Exeter stem and Cenator cemented cup were used in the majority of cases. 16% had acetabular inclination greater than 55 degrees. Radiolucent lines around the cup were seen in 76/113 hips. Femoral stem position was greater than 4 degrees varus in 47/113. Medial floor breach seen in 13/113. 10/113 had leg length discrepancy > 1cm. There were 3 dislocations, 1 femoral fracture, 1 pulmonary embolus, 3 deep infections, 2 superficial infections.

Revision surgery has been performed in 18/113 – the majority for a painful loose acetabular component. A further 5/113 have been recommended for surgery. The further surgery rate was 12% at 2 year follow-up.

The revision rate far exceeds the 0.5% 5-year failure rate reported in the Swedish Registry for the components used. This initiative has left a legacy of unhappy patients, and increased the workload required in our unit to correct the problems. The lack of long-term ownership of patients may be an important factor.

Roentgen Stereophotogrammetric Analysis (RSA) can predict long-term outcome of prostheses by measuring migration over time. The Exeter femoral stem is a double-tapered highly polished implant and has been shown to subside within the cement mantle in 2 year RSA studies. It has a proven track record in terms of long-term survivorship and low revision rates. Several studies have demonstrated excellent clinical outcomes following its implantation but this is the first study to assess stem migration at 10 years, using RSA.

This is a single-centre study involving 20 patients (mean age: 63 years, SD=7) undergoing primary total hip replacement for degenerative osteoarthritis using the lateral (Hardinge) approach. RSA radiographs were taken with the patient bearing full weight post-operatively, at 3, 6, 12 months and at 2, 5 and 10 years follow-up. The three-dimensional migration of the Exeter femoral stem was determined.

The mean Oxford Hip Score at 10 years was 43.4 (SD=4.6) and there were no revisions. The stems subsided and rotated internally during a 10-year period. The mean migrations of the head and tip of the femoral stem in all three anatomic directions (antero-posterior, medio-lateral & supero-distal) were 0.69 mm posterior, 0.04 mm lateral and 1.67 mm distal for the head and 0.20 mm anterior, 0.02 mm lateral and 1.23 mm distal for the tip. The total migration at 10 years was 1.81 mm for the head and 1.25 mm for the tip.

The Exeter femoral stem exhibits migration which is a complex combination of translation and rotation in three dimensions. Comparing our 10 year with our previous 2 year migration results, the Exeter stems show continued, but slow distal migration and internal rotation. The subsidence continues to compress the cement and bone-cement interface which maintains secure fixation in the long term.

Introduction: Percutaneous in situ pinning of severe SUFE can lead to problems. We describe our technique and results for surgical dislocation to reduce severe SUFE.

Method: Ganz’s approach of greater trochanteric flip, safe dissection and surgical dislocation to preserve the femoral head blood supply was followed to anatomically reduce the femoral head. We have treated 16 cases in this way, but describe nine with a minimum follow up of 2 years. Their mean age was 13.6 years (9 to 16 years). All had severe SUFE with four acute on chronic and two unstable slips. Two were previously pinned and another had a partially fused growth plate. The mean follow up was 3.1 years (2.1 to 4.6 years).

Results: All patients had a good to excellent outcome. Their pre-operative deformity was 84 degrees (65 to 110) measured by AP and cross table lateral x-rays, CT or MRI scans. The average hip external rotation deformity was 70 degrees. Post operatively internal and external rotation and all other movements were similar to the contra-lateral uninvolved hip. None developed avascular necrosis (AVN) or chondrolysis

Conclusions: This technique is demanding but can give good results for severe SUFE.

Introduction: Plastic deformation of the regenerate bone is a complication noted soon after limb lengthening. However, less is known about the factors responsible for the development of plastic deformation.

Materials and Methods: Retrospective analysis of 35 X-rays of achondroplast children who had limb lengthening were reviewed. The study compared Monofocal Vs Bifocal and Long lengthenings(> 10 cms) Vs modest lengthenings(≤ 10 cms) of tibial lengthening. Other parameters included in study were Bone healing Index, total length gained and sagittal and coronal axial deformities. There were 20 females and 15 males, 21 long lengthenings and 14 modest lengthenings in the study. The joint orientation and diaphyseal angles(antero-posterior and lateral X-ray views) was used for the measurement of plastic deformation of the regenerate bone.

Results: The mean age at operation was 10 years (range; 6–16 years). There were 29 cases of monolateral fixator and 6 of Ilizarov ring fixator, Of which 26 had monofocal lengthening and 9 had bifocal lengthening (34 callotasis and 1 chondrodiastasis). The total average length gained was 10 cms (range; 23–152). The mean bone healing index and external fixation index/time were 41 days and 352 days respectively. Plastic deformation of the regenerate bone was seen in 26 cases in total. 24 out of 29 cases of monolateral fixator (82%) developed plastic deformation. 44%(4/9) of bifocal group and 84%(22/26) of monofocal group showed evidence of plastic deformation. The long lengthenings showed plastic deformation in 85% (18/21) of the cases, whereas only 57%(8/14) of the cases were positive in modest lengthening group. Most of the axial deviation was in the coronal plane in 92% (24/26) and the sagittal plane accounted to only 23%(6/26) requiring surgical correction.

Conclusions: Long lengthenings and monofocal techniques showed more plastic deformation than bifocal and short lengthenings. However, Ilizarov ring fixator with bifocal corticotomy seemed to be promising with less association with the above entity in our recent experience.

Aim: To review our experience with epiphysiodesis using three different methods to correct LLD and to establish the efficacy of these procedures.

Method: A retrospective review of 42 patients from 1999 to 2008 with at least one year follow-up recorded type and location of the epiphysiodesis, average operating time and hospital stay, complications, method of prediction, timing and the final LLD. CT scanograms and mechanical axis view with grids were used to assess LLD.

Results: Epiphysiodesis was as per Canale for 26, by Metaizeau screw in 14 and by staples in 2. Average operation time was 42 minutes for Canale type, 45 minutes for the screws and 56 minutes for the staple cases. The pre operative LLD of 3.7 cms In the Canale group, improved to 1.2 cms over an average follow-up of 2.1 yrs. There were 4 minor and 2 major complications with a 92% success rate. For the screw group, the mean change was 1.8 cms over 2.2 yrs with 2 minor and 2 major complications giving a success rate of 85%. With staples the success rate was 100% and the mean change was 1.8 cms at an average of 2.3 yrs. In 14 cases where bone age reports were available, the multiplier method seemed better at predicting estimated LLD at skeletal maturity and timing of epiphysiodesis than the Moseley chart.

Conclusions: Percutaneous epiphysiodesis by any method is reliable, minimally invasive and with acceptable complication rate when compared to a corrective osteotomy or open Phemister-type epiphysiodesis. Our experience suggests that the Canale method has the least complications and best success rate. Paleys multiplier method was better at predicting LLD and timing of epiphysiodesis than the Moseley Chart.

Aim: To review our experience with hemi-epiphysiodesis using different methods for the correction of angular deformity about the knee.

Method: This was a retrospective review of 73 patients (101 knees) who underwent hemi-epiphysiodesis from 1999 to 2008. Assessment looked at the type and degree of deformity, implants used, average operating time and hospital stay, complications, degree of correction and the average time to correction.

Results: There were 50 boys and 23 girls with bilateral deformity in 28 cases. There were 88 valgus and 13 varus knees. Average follow-up was 17 months. Staples were used in 28 cases, “8” Plates in 24, Screws in 16 and Drilling in 5 cases. The distal femoral physis was involved in 46 knees, the proximal tibial physis in 21 and both physes in 34 knees (total 135 physes). Average operation time and hospital stay were similar for all methods. There were 6 minor and 3 major complications with staples with an average correction time of 14 months, 3 minor complications with an average correction time of 11 months with “8” plates, 3 minor and 1 major complication with an average correction time of 14 months with screws and 1 minor complication with drilling with an average correction time of 13 months. The outcome was considered as resolved in 47 and pending in 26 cases, with all showing progressive correction of deformity.

Conclusions: Hemi-epiphysiodesis by any method is an effective way to correct angular deformities about the knee in skeletally immature individuals within a reasonable time limit and with minimal morbidity when compared to a corrective osteotomy. Our experience suggests that “8” plates achieve faster correction with the least complications when compared to other methods. Valgus knee deformities corrected faster than varus ones.

The aim of this study was to evaluate the impact of a preoperative education programme on length of hospital stay for primary and revision knee arthroplasty patients.

The programme was introduced at our hospital in October 2006 to encourage patients to play an active role in their postoperative recovery process. It was delivered by a multi-disciplinary team consisting of an arthroplasty nurse, ward physiotherapist, occupational therapist and orthopaedic consultant. Patients were educated about their care pathway, knee surgery, pain management, the expected discharge goal, post operative inpatient and outpatient rehabilitation. Data was prospectively reviewed for 472 patients who underwent (primary or revision) knee arthroplasty for the period between January 2006 and November 2007. There were 150 patients in the Conventional group and 322 patients in the Educational group. The mean length of stay reduced significantly from 7 days in the Conventional group to 5 days in the Education group (P< 0.01). In addition 20 percent more patients were discharged early (within 1 to 4 days) in Education group compared to the Conventional group (P< 0.01). There was no statistically significant difference in the percentage of inpatient complications and readmissions between the two groups.

Our study demonstrates that preoperative education is a safe and effective method of reducing length of stay for knee arthroplasty patients. Significantly more patients achieved discharge within four postoperative days.

Introduction: Obligatory external rotation during flexion is well recognised as a cardinal feature of Slipped Upper Femoral Epiphyses (SUFE). We have evaluated the significance of acetabular version in contributing to the external rotational deformity that is seen in otherwise normal hips. We present a small case series focussing on the characteristics of this pathology, highlighting its significance and outlining a treatment strategy.

Method: Five patients (eight hips) presented with disabling hip pain during non-sporting activities. All their hip radiographs had been reported as normal. The rotational profile of both acetabulum and femur in these patients was evaluated by MRI and CT scans.

Results: Clinical examination revealed otherwise normal hips but for an external rotation deformity which got worse on hip flexion. The average external rotation deformity with the hip in extension was 60 degrees, which worsened to 90 degrees during hip flexion. Three of these hips had been previously treated with in situ pinning for SUFE. Other hips were in patients who were either skeletally mature or close to skeletal maturity. We found that all were “profunda hips” with severe acetabular retroversion. The abnormality in acetabular version was best defined on axial imaging.

Conclusions: The femoral head is a spherical conchoid. The concept of version of the hip (both femoral and acetabular) as described by McKibbin, Tonnis and Ganz is reviewed. Femoral retroversion is common in patients with SUFE, but the addition of acetabular retroversion makes these hips disproportionately symptomatic. This deformity causes a combination of pincer and cam impingement, which is responsible for the marked disability. SUFE alone causes cam impingement, whilst a corresponding degree of slip without retroversion and profunda of the acetabulum is not that disabling.

Introduction: Despite the satisfactory short-term implant survivorship of MoM hip resurfacing arthroplasty, symptomatic abnormal periprosthetic soft-tissue masses relating to the hip joint, ‘pseudotumours’, are being increasingly reported. These were found be locally destructive, requiring revision surgery in 75% of patients. Asymptomatic pseudotumours have not been previously investigated.

Methods: The aims were: (1) to investigate the prevalence of asymptomatic pseudotumours; and (2) to investigate their potential association with the level of metal ions. A total of 160 hips in 123 patients with a mean age 56 years (range 33–73) were evaluated at a mean follow-up of 61 months (range 13–88). Radiographs and OHS were assessed. Patients with a cystic or solid mass detected on the ultrasound/MRI had an aspiration or biopsy performed. Cobalt and chromium levels were analysed using Inductively-Coupled Plasma Spectrometer.

Results: Pseudotumours were found in 6 patients (5F: 1M). In 80% of bilateral cases, it was found in both sides. Histological examination showed extensive necrosis and diffuse lymphocyte infiltration. The presence of pseudotumour was associated with higher serum cobalt (9.2 μg/L vs. 1.9μg/L, p< 0.001) and chromium levels (12.0μg/L vs. 2.1μg/L, p< 0.001); higher hip aspirate cobalt (1182 μg/L vs. 86.2μg/L, p=0.003) and chromium levels (883μg/L vs. 114.8μg/L, p=0.006); and with inferior OHS (23 vs. 14 p=0.08).

Discussion: The prevalence of asymptomatic pseudotumour (5%) was higher than previously reported for the symptomatic pseudotumours (1%). There was a sixfold elevation of serum and a twelve-fold elevation of hip aspirate levels of cobalt and chromium in patients with pseudotumours. This suggests that pseudotumours may be a biological consequence of the large amount of metal debris generated in vivo. The association between pseudotumour and elevated metal ion levels might theoretically be explained by either systemic hypersensitivity responses to metal ions or local cytotoxic effects due to a high level of metal ions.

Purpose: Recent animal evidence has suggested that Bupivicaine may be harmful to articular cartilage. The purpose of this study was establish whether, following arthroscopy of the knee, infiltration of Bupivicaine around the portals is as effective as intra-articular infiltration for post-operative analgesia.

Method: Consecutive patients attending for knee arthroscopy were consented and randomised to one of two groups. Following arthroscopy, Group I received 20mls 0.5% Bupivicaine infiltrated into the joint; Group II received 20mls 0.5% Bupivicaine infiltrated around the portals. A Visual Analogue Score (VAS) was collected at one hour post-operatively and rescue analgesia recorded. A power calculation was performed. Ethical approval was granted.

Results: There were 68 patients in Group I (intra-articular) and 69 patients in Group II (portal). There was no significant difference in the age or sex distribution of patients in either group. The mean VAS score was 3.04 in Group I and 3.24 in Group II. There was no significant difference between the two groups (p=0.619). There was also no significant difference in the need for rescue analgesia (p=0.930). The study has demonstrated equivalence between the two groups, within one VAS point (Power = 80%).

Conclusion: We would recommend that following knee arthroscopy, Bupivicaine should be infiltrated around the portals, avoiding intra-articular infiltration.

Introduction: We report on a group of 20 metal-on-metal resurfaced hips (17 patients) presenting with a soft tissue mass associated with various symptoms; these masses we termed pseudotumours. All patients underwent plane radiography; CT, MRI and ultrasound investigations were also performed for some patients. Where samples were available histology was performed.

Methods: All patients in this series were female. Presentation was variable; the most common symptom was pain or discomfort in the hip region. Other symptoms included spontaneous dislocation, nerve palsy, a noticeable mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. Fourteen of the 20 cases (70%) have so far required revision to a conventional hip replacement and their symptoms have either settled completely or improved substantially since the revision surgery. Two of the three bilateral cases have asymptomatic pseudotumours on the opposite side.

Conclusions: We estimate that about 1% of patients develop a pseudotumour in the first five postoperative years after a hip resurfacing. The cause of these pseudotumours is unknown and is probably multi-factorial, further work is required to define this; they may be manifestations of a metal sensitivity response. We are concerned that with time the incidence of these pseudotumours will increase.

Aim: To assess the ease of use and reliability of PICC lines for the delivery of intravenous antibiotics in children with septic joints.

Method: Over a twelve month period 22 children with septic joints were prospectively recruited. All received open arthrotomy and washout prior to commencing antibiotic treatment. At the time of surgery, a PICC line was inserted. All children were given intravenous antibiotics for two weeks then oral antibiotics for four weeks. Inflammatory blood markers were reviewed regularly. Upon removal of the PICC line the tip was sent for microbiological testing.

Results: All 22 children made a full recovery with a minimum of twelve months follow up (range 12–20 months). All PICC line tips were negative for microbiological culture after 48 hours.

Conclusion: Peripheral cannulation for intravenous access in children can be challenging. Younger children have chubby limbs and often fragile veins. Even with the use of topical analgesics the procedure can be traumatic for a young child. A PICC line inserted at the time of the surgical washout of the infected joint seems an ideal solution. PICC lines are safe, reliable and allow for at least two weeks of intravenous access, avoiding the need for regular re-cannulation of children.

Purpose: To alert the Orthopaedic fraternity that smoking needs to be considered in the Paediatric population and highlight it’s adverse effect on bone healing index.

Method: During assessment of Paediatric patients who had undergone limb reconstruction surgery, a sub-population was found to have a prolonged time to consolidation of the regenerate to norm. Screening for contributing factors, we were surprised to learn that this subgroup were active smokers. Revisiting their radiographs, it was felt that the quality of the regenerate appeared to differ from non-smokers.

Results: We identified 12 patients who were active smokers. 2 also had parents who smoked. They all exhibited a prolonged time to regenerate consolidation. We calculated their bone healing indices to compare with non smokers and found significant differences.

Conclusion: Smoking has adverse effects on bone healing in children as well as adults. We have drawn up an advise sheet to make patients and their parents aware of the adverse effects of active and passive smoking on bone healing.

AIM: The purpose of this prospective study was to asses the outcome of antegrade intramedullary wiring of displaced distal end of fifth metacarpal fracture in skeletally immature. Intramedullary wiring for fracture metacarpals have been well described in the literature. Retrograde wiring for neck of metacarpal fractures have been associated with limitation of extension at metacarpo-phalangeal joint due to involvement of gliding extensor mechanism. Foucher described ‘Bouguet’ osteosynthesis with multiple wires for metacarpal neck fracture which can be technically demanding in small bones of children. We describe an antegrade wiring using a single bent K-wire at the tip for reducing and stabilising displaced metacarpal neck fracture by rotating 180 degree after crossing fracture site, a method similar to Methaizeau technique for stabilisation of displaced radial neck fractures using nancy nail.

METHOD: Between 2000 to 2006 we treated 9 boys with displaced distal end of fifth metacarpal fracture +/− rotational deformity of little finger using above technique. All of them had closed injuries and the indication for surgery was rotatory mal-alignment or fracture angulation more than 40 degrees. The assessment involved a clinical and radiological examination. The mean age was 13 years. The mean follow-up was 15 months.

RESULTS: All fractures healed in anatomical alignment. There was no loss of active or passive movement of the little finger metacarpo-phalangeal joint or weakness of grip strength in any children. All children returned to pre-injury activity level within 4–6 weeks. There were no complications.

CONCLUSION: Early results of treating displaced little finger metacarpal neck fracture in children using antegrade intramedullary wire are encouraging.

Aim: Spinal stenosis is a known entity in achondroplasia and a need for screening for the symptomatic children was identified in a tertiary limb reconstruction service. The aim of this study was to evaluate whether clinical and radiological imaging would identify the at risk group.

Materials and methods: 205 achondroplastic children were treated at our service in the last 20 years. A prospective clinical screening programme for spinal stenosis which also included the MRI imaging of entire spine was however introduced only in 1996. 26 patients were available for this study. Case notes were reviewed for clinical symptoms and neurological signs. MR images were assessed for stenosis especially at Cervico medullary junction and lumbar level. Canal diameters were measured at all spinal levels from CMJ to lumbo-sacral junction. Neurosurgical interventions were recorded. An attempt was made to identify high risk factors that required surgical intervention.

Results: Delayed milestones were observed in 7 patients. Positive history of back pain or radicular pain was obtained in 10 whereas 10 patients had symptoms of neurogenic claudication. Brisk reflexes and clonus were consistent findings. Severe foramen magnum narrowing was observed in 23 patients and 13 showed ‘kinking’ or ‘pinching’, suggesting severe compression. Of the 17 patients seen by neurosurgeons 6 required single or multiple surgical decompressions. Ventriculo-peritoneal shunt was inserted in 4. 5 children required CMJ decompression and one required lumbar canal decompression. There was a 7 mm difference in AP diameter measured on MRI at CMJ between the two non operated and operated groups. Female patients with delayed milestones and CMJ narrowing to less than 25 mm were identified as high risk.

Conclusion: The cause of increased morbidity and mortality in young achondroplasts is attributable to severe CM compression. Sudden death can occur by acute or gradual progressive encroachment of respiratory centre at medulla oblongata. We were able to identify symptomatic patients early before developing myelomalacia and cord changes by screening all symptomatic children with achondroplasia. We propose that female gender, especially with delayed milestones as another high risk factor. We stress upon the importance of developing a nationalised selective screening programme with guidelines in specialist orthopaedic and joint multi-disciplinary Skeletal Dysplasia clinics.

Introduction: Ankle fractures accounts for 25% to 38% of all physeal fractures. An accurate diagnosis is the key to the appropriate management of these fractures. Traditionally the management decisions have been based on x-ray findings. We have used computed tomograpy (CT) scans in additon to x-rays in the management of these fractures.

Objective: To determine the usefulness of computed tomograpy (CT) scans in the management of ankle fractures in children.

Materials and Methods: Between 2001 to 2005, 53 patients with ankle fractures who were managed in our unit had CT scans in addition to plain radiographs. The mean age was 12.3 years (+/− 2.1). The radiographs were reviewed by senior paediatric orthopaedic surgeon who classified the fractures and formulated treatment plans (operative/non-operative). The CT scans were then reviewed by the respective surgeon and a similar exercise undertaken. A Radiologist confirmed that the fractures were classified accurately.

Results: In 47% (25 fractures) the x-ray diagnosis/classification tallied with the CT scans whilst in 53% (28 fractures) the CT scans showed the fractures were more extensive/serious than noticed on the x-rays. The management was changed in 34% after reviewing the CT scans, In 9 from operative to non-operative treatment and in the other 9 from non-operative to operative treatment.

Conclusion: We have found CT scans to be more useful than plain radiographs in making an accurate diagnosis of ankle fractures in children and thus planning appropriate management.

Introduction: Interest in hip resurfacing has recently been renewed by the introduction of metal-on-metal designs; it is being increasingly used for young patients, with over 30,000 implanted worldwide. The 5 year clinical results appear promising, but there are no long term data available. Radiostereometry (RSA) measures of implant migration have been able to predict implant failure; specifically large and continuous migration predicts aseptic loosening. We present the results of a five year RSA study examining the migration of the Birmingham Hip Resurfacing (BHR).

Methods: Twenty-four subjects with primary OA were implanted with the BHR device and with bone markers for RSA. RSA measurements were taken at 3, 6, 12, 24 and 60 months. The migration of the head and the tip of femoral component were measured in 3D.

Results: Preliminary analysis showed that the total 3D migration of the head and tip over five years was 0.32mm and 0.23mm respectively.

Discussion: A distal migration of more than 0.4mm over 2 years increases the likelihood of failure in conventional stems. The total migration of the BHR was approximately 0.3mm over a five year period, significantly less than cemented THR devices. The device is stable and this is promising for long-term survival.

Aims: The aims of our study were:

to measure the total metal content in cell saver blood recovered during revision hip arthroplasty,

Materials and methods: We analysed the levels of metallic debris and metal ions in cell saver blood in nine patients undergoing revision hip replacement. Using inductively coupled plasma mass spectrometry (ICP-MS), the levels were measured for titanium, aluminium, vanadium, chromium, cobalt, nickel and molybdenum. The metal ion levels were analysed using a dilution technique and the total metal content levels (particulate debris and ions) were analysed with a digestion technique.

Results: Significantly higher levels of metal ions and metal debris were found in the pre-processed blood compared with the processed blood (after centrifuging and washing). The ion levels in the processed blood were not high enough to cause a significant increase in the patients’ immediate post-operative blood ion levels when compared with pre-operative levels.

Discussion: There are markedly elevated levels of metal ions and particulate metal debris in the blood salvaged during revision total hip arthroplasty. The processing of the recovered blood in a commercial “cell saver” significantly reduces the total metal load that is re-infused. Re-infusion of salvaged blood does not result in elevated metal ion levels in the immediate post-operative period.

Aim: To determine the outcome and need for subsequent surgery in patients following successful closed reduction of dislocation after primary total hip arthroplasty (THA) and the financial implications of re-operation.

Methods: Data was retrospectively obtained from radiographs and patient case notes for all dislocated primary hip replacements presenting to the University Hospital of Wales from January 2000 till November 2005. Records were analysed with a minimum of 1 year follow-up to determine the outcome and need for subsequent surgery following successful closed reduction of dislocation after primary THA. Factors studied include age at primary surgery, indications, components, approach, head size, duration since surgery and direction of dislocation

Results: Over the 6 year study period, 98 patients presented with 100 first time dislocated primary total hip replacements. All the dislocations underwent successful closed reduction. 62 (62%) hips re-dislocated more that once. At minimum follow up of 1 year, 7 patients had died and were excluded from the final study group. Of the remaining 93 hips, 46 patients have had no further surgery. 44 THA’s have undergone revision procedures and 3 are waiting to have revision surgery (51% in total). Of those who have undergone revision surgery, 7 hips re-dislocated since and 3 of those needed further re-revision.

Discussion: Dislocation following primary THA remains a problem with varying dislocation rates quoted in the literature. In our series, 51% of patients presenting with dislocation required revision surgery. All patients in this series had 28 mm or smaller femoral heads. The financial impact of the burden of revision surgery continues to increase. In this series in isolation the cost of revision surgery totalled greater that £500,000.

Aim: To investigate the outcome following revision total hip arthroplasty (THA) using 36 mm and 40 mm modular femoral heads.

Methods: Details were retrieved from our arthroplasty database regarding all revision THAs done in our unit using 36 mm and 40 mm femoral heads. Follow-up information was obtained from patient records and telephone conversation.

Results: The cohort considered totalled 107 revision THAs, 93 using a 36 mm head and 14 using a 40 mm head. All received either highly cross-linked UHMWPE liners or metal on metal liners. The indications for revisions were recurrent instability in eight, periprosthetic fracture in 11, second stage revision in 24, fracture of the femoral stem in one and aseptic loosening in the remaining 63. At a minimum follow up of one year, information was not available for five but they did not have any record of dislocation. Out of the remaining 102 patients, dislocation occurred in 4 hips (3.9%). None of the revisions done with 40 mm head dislocated. In two of the dislocations, the initial indication for revision THA was recurrent instability and if they are excluded, the dislocation rate was 1.96%.

Discussion: Dislocation and the sequalae of recurrent instability remains a significant problem following revision THA and the existing literature varies greatly in the quoted dislocation rates. We believe that the use of 36 mm and 40 mm femoral heads in our unit has been a major factor in low (3.6%) dislocation rate following revision THA. To date there have been no problems encountered resulting from the use of highly cross-linked UHMWPE.

Purpose of study: We report the results of a prospective case series of 10 patients who developed tumour-like masses following resurfacing arthroplasty

Method: Ten subjects were referred to the tumour service at the Nuffield Orthopaedic Centre with symptomatic masses around the hip, all had previously received a resurfacing arthroplasty.

We report the clinical, radiographic and histologic features of these cases.

Results: MRI and ultrasound scanning was preformed, which demonstrated masses with solid and cystic components.

Biopsy was performed and subsequent histological examination revealed a profound plasma-cell lymphocytic response associated with metal wear debris.

There were no infections in this series.

Three subjects required revision surgery.

Conclusion: Over 50,000 resurfacing arthroplasties have been implanted worldwide over the past ten years. Although the early clinical results are encouraging little is known about the long term consequences of large head metal on metal bearing surfaces. Despite this, these devices are being widely marketed and are often implanted in younger patients. Resurfacing arthroplasties are associated with high serum and urine metal ion concentrations, metal particles have also been shown to migrate along the lymphatic system. In addition, there is now evidence that high local metal ion concentrations can induce haempoietic cancers.

This study suggests that resurfacing arthoplasty can also induce a local hypersensitivity reaction in response to metal wear debris. It therefore raises new concerns regarding the long-term safety of this procedure.

Purpose: The aims of our study were: (i) to measure the total metal content in cell saver blood recovered during revision hip arthroplasty, (ii) to evaluate the efficacy of centrifuging and washing the recovered blood in reducing the metal content, (iii) to investigate whether transfusion of the salvaged blood resulted in a significant increase in the metal ion levels in the patients’ blood in the immediate post-operative period.

Materials and methods: We analysed the levels of metallic debris and metal ions in cell saver blood in nine patients undergoing revision hip replacement. Using inductively coupled plasma mass spectrometry (ICP-MS), the levels were measured for titanium, aluminium, vanadium, chromium, cobalt, nickel and molybdenum. The metal ion levels were analysed using a dilution technique and the total metal content levels (particulate debris and ions) were analysed with a digestion technique.

Results: Significantly higher levels of metal ions and metal debris were found in the pre-processed blood compared with the processed blood (after centrifuging and washing). The ion levels in the processed blood were not high enough to cause a significant increase in the patients’ immediate post-operative blood ion levels when compared with pre-operative levels.

Conclusion: There are markedly elevated levels of metal ions and particulate metal debris in the blood salvaged during revision total hip arthroplasty. The processing of the recovered blood in a commercial ‘cell saver’ sig-nificantly reduces the total metal load that is re-infused. Re-infusion of salvaged blood does not result in elevated metal ion levels in the immediate post-operative period.

Introduction: Prophylactic pinning of an asymptomatic hip in SCFE is controversial. Bone age has been used as evidence of future contralateral slip risk and used as an indication for such intervention. The efficacy of bone age assessment at predicting contralateral slip was tested in this study.

Patients and Methods: 18 Caucasian children prospectively had bone age assessment using wrist and hand x-rays when presenting with a unilateral SCFE. Patients and parents were informed about the chance of con-tralateral slip and risks of prophylactic fixation, and advised to attend hospital immediately on development of symptoms in contralateral hip. After in-situ fixation of the affected side prospective monitoring in outpatient department was performed. Surgical intervention was undertaken if the contralateral hip was symptomatic.

Results: Three children (2 boys) went on to develop to a contralateral slip at a mean of 20 months from initial presentation. 6 children (5 boys) were deemed at risk of contralateral slip due to a bone age below 12.5 years for boys and 10.5 for girls. Only one from this group developed a contralateral slip. The relative risk of proceeding to contralateral slip when the bone age is below the designated values was 1 (95% confidence interval of 0.1118 to 8.95). The sensitivity and specificity were 33% and 66% respectively. With positive predictive value of 15% and diagnostic efficiency of 61%.

Conclusion: Delayed bone age by itself is not a good predictor of future contralateral slip at initial presentation. Routine prophylactic pinning is not justified based on bone age alone, with the risks of surgical fixation it carries. Prospective long term longitudinal study is required.

Introduction: Prophylactic pinning of an asymptomatic hip in SCFE is controversial. Bone age has been used as evidence of future contralateral slip risk and used as an indication for such intervention. The efficacy of bone age assessment at predicting contralateral slip was tested in this study.

Patients and Methods: 18 Caucasian children prospectively had bone age assessment using wrist and hand x-rays when presenting with a unilateral SCFE. Patients and parents were informed about the chance of con-tralateral slip and risks of prophylactic fixation, and advised to attend hospital immediately on development of symptoms in contralateral hip. After in-situ fixation of the affected side prospective monitoring in outpatient department was performed. Surgical intervention was undertaken if the contralateral hip was symptomatic.

Results: Three children (2 boys) went on to develop to a contralateral slip at a mean of 20 months from initial presentation. 6 children (5 boys) were deemed at risk of contralateral slip due to a bone age below 12.5 years for boys and 10.5 for girls. Only one from this group developed a contralateral slip. The relative risk of proceeding to contralateral slip when the bone age is below the designated values was 1 (95% confidence interval of 0.1118 to 8.95). The sensitivity and specificity were 33% and 66% respectively. With positive predictive value of 15% and diagnostic efficiency of 61%.

Conclusion: Delayed bone age by itself is not a good predictor of future contralateral slip at initial presentation. Routine prophylactic pinning is not justified based on bone age alone, with the risks of surgical fixation it carries. Prospective long term longitudinal study is required.

The Charnley Elite femoral component was first introduced in 1992 as a new design variant of the original Charnley femoral component (De Puy, Leeds, UK) with modified neck and stem geometry. The original component had undergone few changes in nearly forty years and has excellent long-term results. Early migration of the new stem design was determined by Roentgen Stereophotogrammetric Analysis (RSA)1. Rapid early migration of a component relative to the bone, measured by RSA, is predictive of subsequent aseptic loosening for a number of femoral stems. As there was rapid early migration and rotation of the Charnley Elite stem, we predicted that the long-term results would be poor. An outcome assessment is indicated as stems of this type are still being implanted.

One hundred Charnley Elite stems, implanted in our centre between 1994 and 1997 were included in a prospective, cross-sectional follow-up study. Outcome measures include validated clinical scores (Charnley hip score, Harris hip score and Oxford hip score) and radiological scores (Gruen classification) as well as revision rates over the past 10 years.

The clinical follow-up supports the RSA predictions of early failure of the Charnley Elite femoral stem.

Introduction: The assessment of bone age using the standard Gruel and Pyle chart based on hand and wrist radiographs is usually carried out by Senior Radiologists. We performed a study to look at both intra and inter observer variability with different grades of clinicians.

Materials and Methods: 30 sets of wrist radiographs were selected at random. The investigators included a Senior Radiographer, a Consultant and Registrar Radiologist an Orthopaedic Consultant and Senior Orthopaedic Fellow.

Discussion: The Radiology team appear to be more consistent in their readings for the assessment of skeletal bone age than the Orthopaedic team. Howevr, it is interesting to note that although the Orthopaedic team are less consistent, when looking at the inter-observer variability, it suggests that both teams are equally well equipped to perform the task.

Conclusion: Our study suggests that we should not cross professional boundaries. Render unto Caeser what is Ceaser’s!

Aim of the study: To evaluate the final outcome following joint distraction and reconstruction in patients with complex knee contractures in a select group with varied aetiology.

Materials and methods: Retrospective study of six patients (nine knees, 3 bilateral) with severe knee flexion contractures treated by gradual distraction using ring fixators. Most cases were syndromic or arthrogrypotic.. Case notes and radiographs were reviewed to assess the mobility and functional range of motion before and after the procedure.

Results: Staged procedures was carried out in 6 out of 9 knees accompanied by soft tissue releases, realignment of extensor mechanism and bony and joint realignment. The average age at operation was nine years and nine months and the mean follow up was 53 months. The average time spent in frame was 20 weeks. The correction was graded as good to excellent in 5 knees, fair in 1 and poor in 3 knees. The total arc of motion remained unchanged though the functional range of movement improved. The mobility improved significantly in most patients who were independent walkers with or without splints. Complications were of rebound phenomenon after frame removal in arthrogrypotic children, transient neuropraxia of common peroneal nerve in 2 epiphyseal separation in one and 3 sustained undisplaced fractures during mechanical distraction.

Conclusion: Syndromic and arthrogrypotic knee contractures are difficult to treat due to their severity and complexity. Planned staged procedures with joint distraction, patellar and bony realignment can produce satisfactory outcome in most making them functional independent ambulators.

Aim: To report our experience and early results with the Ilizarov pelvic support realignment lengthening osteotomy for complex hip pathology in children.

Material & Methods: Between 1997 & 2004, seven children were treated with this technique and five have completed treatment. The treatment was undertaken for sequelae of DDH in 4 patients and septic arthritis in 1 patient. The median age of the patients was 13(10–17). There were 3 boys and 2 girls. The outcome assessment was performed using the Harris hip score, clinical and radiological parameters.

Results: 4 patients presented with hip instability, shortening of the lower limb, pain and restricted motion. The remaining patient presented with a nonfunctional ankylosis with shortening. The median time between the onset of symptoms and the operation was 3 years (2–5). The median preoperative leg-length discrepancy was 3 cm (2–4.5). The median fixator time was 5 months (3–6). The median follow-up was 24 months (9–72).

Patients had improvement of pain, posture, hip instability, walking ability and limb length discrepancy. The median lengthening of the femur was 3 cm (2–5). The mechanical axis was realigned in all patients. All patients were satisfied with the outcome. Planned secondary contra lateral epiphyseodesis was required to equalise leg length in 2 patients. Complications included a stiff knee (1) that required a Judet quadricepsplasty, premature consolidation (1) that required reosteotomy and knee subluxation (1) that required cross knee stabilisation.

Conclusion: This is a safe and reliable alternative option to joint replacement, Colonna arthroplasty and arthrodesis for the reconstruction of multiply operated complex hip pathology in children.

Purpose: The aim of this part retrospective and part prospective study was to establish the incidence of pinsite infections and assess evolution of changes in practice

Methods: Data was collected retrospectively and prospectively for pin site infections from the inception of limb reconstruction service viz. 1985 to January 2002. There were 812 patients, 1042 limb segments, and 9935 pins. The various external fixators used were limb reconstruction system (LRS) 549; Ilizarov 397; Sheffield ring fixator (SRF); Dynamic axial fixator (DAF) 35; LRS/Sequoia 8; LRS/Garche 7; and Pennig 5.

Results: The pin site infections were graded from 0 to 6 ( Saleh & Scott). There were no infections in 206 segments. The infection grade is shown below:

We changed our pin tract care practice from 1996. We had a significant decrease in pin tract infections since then (p< 0.0001). We also found that using Ilizarov wires had significantly less infections than with half pins used with monolateral fixators (p< 0.0001; linear trend, p= 0.0338). There were 48 patients that required hospital admissions for IV antibiotics. and of these 10 patients required debridement. There were no residual long lasting infections or chronic osteomyelitis.

Conclusion: Attention to detail in insertion of wires and half pins is crucial to avoid pin site infections. This audit supports the fact that external fixation is a safe method from the point of view of infection contrary to general belief.

Introduction: The design philosophy of polished tapered THR stems, such as the Exeter, intend for them to migrate distally within the cement mantle. In addition it is likely that micromotion occurs as a result of functional activity. The pattern of induced stresses will be a function of stem geometry & surface finish, as well as applied loading. Aim: To investigate the stresses induced in the cement mantle of a polished tapered THR stem during functional activity.

Method: Using Roentgen Stereophotogrammetric Analysis (RSA) dynamically induced micro-motion (DIMM) was measured in 21 patients implanted with Exeter stems. DIMM was measured as the difference in stem position in going from double to single leg stance on the operated limb. All subjects were measured 3 months post-operatively. A finite element (FE) model of the femur, including all muscles was used to investigate the stress distribution within the cement; contact was modelled with sliding elements allowing separation. The model was validated by comparison to the DIMM measurements.

Results: The Exeter stem demonstrated significant DIMM(p < 0.017), the average motions are given in the table below. The FE model, with sliding contacts was able to predict similar distal migration of the head. The peak minimum principal stress in the mantle was approx 33MPa and occurred in the proximal medial region. Movements occurred at the stem/cement interface.

Discussion and Conclusion: It is possible to measure DIMM in the Exeter stem and combining this with FE modelling the mechanism of stress transfer between the stem and mantle can be investigated in a manner that can be validated.

Introduction: Prophylactic pinning of an asymptomatic hip in SCFE is controversial. Bone age has been used as evidence of future contralateral slip risk and used as an indication for such intervention. The efficacy of bone age assessment at predicting contralateral slip was tested in this study.

Patients and Methods: 18 Caucasian children prospectively had bone age assessment using wrist and hand x-rays when presenting with a unilateral SCFE. Patients and parents were informed about the chance of contralateral slip and risks of prophylactic fixation, and advised to attend hospital immediately on development of symptoms in contralateral hip. After in-situ fixation of the affected side prospective monitoring in outpatient department was performed. Surgical intervention was undertaken if the contralateral hip was symptomatic.

Results: Three children (2 boys) went on to develop to a contralateral slip at a mean of 20 months from initial presentation. 6 children (5 boys) were deemed at risk of contralateral slip due to a bone age below 12.5 years for boys and 10.5 for girls. Only one from this group developed a contralateral slip. The relative risk of proceeding to contralateral slip when the bone age is below the designated values was 1 (95% confidence interval of 0.1118 to 8.95).

Conclusion: Delayed bone age by itself is not a good predictor of future contralateral slip at initial presentation. Routine prophylactic pinning is not justified based on bone age alone, with the risks of surgical fixation it carries. Prospective long term longitudinal study is required.