Introduction

Catastrophic neck injury is rare in rugby, however the consequences are invariably devastating. Schoolboys have previously been identified as a group at risk. This study came about as a result of a recent increase in admissions of schoolboy rugby players to the National spinal injuries unit in Glasgow.

Prosthesis migration and acetabular cup wear are useful short term measurement which may predict later implant outcome. However, the significance of the magnitude and pattern of the migration is very much dependent on the specific design studied. This study aimed to characterise patterns of migration by following four cemented femoral stem designs using Radiostereometry (RSA) within a prospective randomised longitudinal trial.

164 patients undergoing cemented femoral hip replacement for osteoarthritis were randomised to receive either an Exeter (Howmedica Stryker), Ultima Tapered Polished Stem (TPS) (Depuy), Ultima Straight Stem (USS) (Johnson and Johnson) or Elite Plus (Depuy) stem. Each subject received the OGEE PE cemented acetabular component (Depuy). RSA examinations were performed at 1 week and 6, 12, 18, 24 and 60 months post surgery. They were analysed using the UMRSA system (RSA Biomedical AB, Umea, Sweden), and our local geometric stem measurement software. 149 patients had RSA measurements available to 2 years, and 96 patients to 5 years. Differences were analysed using mixed linear modelling (SPSS).

Median linear proximal cup wear rate reduced to a minimum of 0.02-0.06mm/year in year two. Between 2 and 5 years the wear rate increased, being significantly higher for the Elite.

Cup migration was small but continuous. At 2 years it was median 0.3mm proximally, increasing to 0.5 mm at 5 years. Median rotations were less than 0.3 degrees.

Proximal migration was positive and increasing at all time points for all stems. For the tapered polished designs, while the overall magnitude was significantly higher, the rate of migration significantly decreased, whereas for the other stem designs it did not.

The TPS stem showed a tendency for posterior tilt which was significant compared to the other stems at 5 years.

All stems tended to retroversion, with the USS significantly less than the others and the Elite showing and relative increase at 5 years.

In summary migration patterns are characterised by the stem design, including where there were only small changes between designs. We are now testing measured migrations as predictors of outcome, and will continue to follow this group of patients to 10 years.

Although it has long been appreciated that a healthy balanced diet improves health, there is a growing understanding of the way in which certain nutrients can actually improve immune function. Boosting immune function by the use of “immunonutrition” has been shown to improve outcomes, in particular rates of infective complications, in certain groups of surgical patients.

In this study we examine the immune status of elderly patients who have suffered a hip fracture and are known to be vulnerable to infection and poor post-operative outcomes to identify specific immune defects associated with this particular cohort. This may allow us to explore the potential benefits of immunonutrition in this group of patients in the future.

This was a cohort observational study, in which a series of 16 patients who underwent surgery for hip fractures were followed. The patients were female patients with an age of 60 to 85 years and a mental status questionnaire score of at least 8 out of 10.

Immune function was evaluated prior to surgery, on the day following surgery and then at between days 4 and 7 post-operatively. Samples were tested directly ex-vivo using a variety of flow cytometric assays.

We report profound loss of innate immune function related specifically to monocyte and granulocyte ability to generate a respiratory burst in response to E.coli uptake persisting up to day 7 post-operatively. In addition, serum cytokine levels indicated very poor T cell function, in identifying these patients as particularly vulnerable to infections.

The ‘cement reaction’ is a recognised cardio-respiratory response to methylmethacrylate bone cement, characterised by hypotension, reduced cardiac output, and on occasion fatal circulatory collapse. It is seen in 0.5-1% of cemented hip arthroplasties during the insertion and pressurisation of cement into the femur, and is believed to be secondary to marrow thromboembolism, the vasodilatory effect of methylmethacrylate, or a combination of the two. A number of steps, within the operating surgeon's control, can be undertaken to reduce the risk of the ‘cement reaction’ occurring.

An e-mail based questionnaire was sent to all trainees and consultants in the West of Scotland containing eight questions relating to cementing technique when performing hemiarthroplasty of the hip. The questions related to measures to reduce the potential for ‘cement reaction’, e.g.: whether or not they routinely use a cement restrictor.

Seventy-two complete replies were received. For five of the eight measures, the surgeons routinely employed the suggested practices. For the remaining three, the consensus opinion was contrary to the suggested practice for reduction of the risk of ‘cement reaction’. These were with respect to the surgical approach employed, whether or not to attempt to remove all cancellous bone from the proximal femur, and the use, or not, of a venting tube during cement insertion. In all three cases, the difference was statistically significant on chi-squared testing.

The cohort of surgeons questioned routinely employ more than half of the methods suggested to reduce the potential for ‘cement reaction’ in hemiarthroplasty of the hip. Further surveys of why they do, or do not, undertake certain practices during cementing would help improve awareness of ‘cement reaction’, and perhaps reduce the incidence of this potentially fatal phenomenon.

Introduction: Impaction allografting is an established method for restoring deficient bone during revision arthroplasty of the hip. Graft augmentation with synthetic materials has been proposed and evaluated experimentally. Our aim was to assess clinically whether migration and wear of implants with a synthetic graft mix would be equivalent to pure allograft.

Materials and Methods: Patient inclusion criteria were: acetabular and or femoral defects from aseptically loosened primary THR undergoing cemented revision with impaction grafting; age 55–80 years; initial diagnosis of osteo arthritis; good health with reasonable daily activity level. Patients were randomized to receive either pure allograft or a 50% mixture with a porous hydroxyapatite material (Apapore60, Apatech, UK). Revision was with the Exeter stem, antibiotic Simplex cement (Stryker Howmedica Ltd), and Ogee cup (Depuy Int. Ltd., Leeds, UK). Tantalum markers were inserted into the pelvis, cup, femur, cement and graft in order to measure migration with radiostereometry (RSA). Patients received a sequence of RSA examinations up to 2 years. A total of 26 patients (18 for the femur) have been analysed.

Results: At 2 years no significant differences were seen in cup wear, or migration of the cup, femoral and pelvic graft markers. Stem migration occurred mainly at the stem cement interface. The rate of distal migration for the femoral head was greater for pure allograft in the first year (p < 0.05), however this rate reduced significantly in year two. Higher medial migration in year one was observed for the proximal medial cement mantle for allograft (p < 0.05).

Conclusions: Improved stability and normal cup wear were observed in a randomized clinical study for a synthetically augmented allograft. This agrees with experimental findings¹. Longer follow up with increased patient numbers is recommended to confirm these findings.

Synthetic graft expanders have recently been developed for use in impaction grafting revision hip arthroplasty, but their true role has yet to be determined.

We performed a series of experiments to investigate the properties of one such porous hydroxyapatite material (IG-Pore, ApaTech Ltd). IG-Pore was mixed with fresh-frozen human allograft chips and impacted into composite femoral models with a similar biomechanical profile to human bone (Sawbones Europe). Exeter hip prostheses (Stryker Howmedica Ltd) were implanted with cement and each model was axially loaded for 18000 cycles at physiological levels using an Instron servohydraulic materials testing machine. Four test groups with 0%, 50%, 70% and 90% IG-Pore were used, and there were eight femora in each group.

Pre- and post-loading radiostereometric analysis was performed to characterise migration of the prosthesis. Total subsidence was measured and was separated into that occurring at the prosthesis-cement and cement-femur interfaces. Cyclical compression and expansion of the graft-containing models was measured using the Instron.

Median values (interquartile range) for total subsidence were 0.43 mm (0.28 to 0.55) for the pure allograft group, 0.31 mm (0.20 to 0.55) for the 50% IG-Pore group, 0.23 mm (0.07 to 0.34) for the 70% allograft group and 0.13 mm (0.06 to 0.18) for the 90% IG-Pore group. These differences were statistically significant (p=0.034, Kruskal-Wallis). Subsidence at the prosthesis-cement interface was also lower for IG-Pore containing models (p=0.019, Kruskal-Wallis), although there was no significant difference at the cement-femur interface. Specimens with a higher proportion of IG-Pore showed smaller cyclical movements on loading (p=0.005, ANOVA).

Higher proportions of IG-Pore do appear to reduce subsidence in a mechanical model of impaction grafting. A randomised clinical trial using RSA to compare a 50% IG-Pore/allograft mix with pure allograft is in progress to investigate the use of this material as a bone graft expander in the clinical setting.

The Scottish Hip Fracture Audit (1) was founded on Rikshoft, the Swedish hip fracture register (2), and since 1993 has documented case-mix, process and outcomes of hip fracture care in Scotland. Evidence-based national guidelines on hip fracture care were updated by a multidisciplinary group in 2002(3). And hip fracture serves as a tracer condition by the health quality assurance authority for its work on older people, which reported in 2004 (4).

Audit data are used locally to document care and support and monitor service developments. Synergy between the guidelines and the audit provides a means of improving care locally and monitoring care nationally. External review by the quality assurance body shows to what extent guideline-based standards relating to A& E care, pre-operative delay, multidisciplinary care and audit participation are met.

Three national-level initiatives on hip fracture care have delivered: reliable and largescale comparative information on case-mix, care and outcomes; evidence-based recommendations on care; and nationally accountable standards inspected and reported by the national health quality assurance authority. These developments are linked and synergistic, and enjoy both clinical and managerial support. They provide an evolving framework for clinical governance and quality assurance, with methods for casemix-adjusted outcome assessment for hip fracture care also now developed.

Impaction grafting procedures have found a widespread role in revision hip arthroplasty. Synthetic graft expanders have recently been introduced, but the optimal ratio of expander to allograft is unknown.

We performed a series of in vitro experiments to investigate the optimal ratio for one commercially available porous hydroxyapatite material (IG-Pore, ApaT-ech Ltd). IG-Pore was mixed with fresh frozen human allograft chips from osteoarthritic femoral heads and with blood. Graft was impacted into fibre-glass femoral models (Sawbones Europe) with a similar biomechanical profile to human bone, and Exeter hip prostheses (Stryker Howmedica Ltd) were cemented in place. Each model was loaded using an Instron servohydraulic materials testing machine for 18000 cycles. The magnitude and frequency of the loading cycle was based on physiologically measured values. Four test groups with 0%, 50%, 70% and 90% IG-Pore were used, with eight femora in each group.

Tantalum marker beads were attached to the prosthesis, the femoral model and the cement mantle, and radio-stereometric analysis (RSA) was performed pre- and post- loading to determine migration and rotation of the prosthesis in each axis. Pre-loading films were repeated in sixteen cases for precision measurements, and twelve specimens had delayed post-loading films performed to measure any re-expansion of the unloaded graft.

The primary end-point was RSA-measured subsidence of the prosthesis, defined as vertical movement of the tip. Median subsidence was 0.43mm, 0.31mm, 0.24mm and 0.13mm in the 0%, 50%, 70% and 90% IG-Pore groups respectively (P=0.034, Kruskal-Wallis test). The precision, given as the median absolute difference, was 0.0065mm.

All specimens showed a cyclical compression and expansion throughout the loading cycle. Specimens with a higher proportion of IG-Pore tended to be more resistant to this and the mean values for cyclical movement were 1.76 0.27mm, 1.65 0.21mm, 1.57 0.18 mm and 1.45 0.14mm for the 0%, 50%, 70% and 90% IG-Pore groups.

Higher proportions of IG-Pore appear to reduce subsidence in impaction grafting. Other issues such as the handling qualities of the graft and the biological effect of synthetic materials also need to be considered, however. A randomised clinical trial using RSA to evaluate a 50% IG-Pore/allograft mix in comparison to pure allograft is ongoing in our institution, and we hope that this will answer some of these questions definitively.

Aims: To study prospectively the characteristic migration of four different cemented femoral stems using Radiostereometry. Methods: 96 patients undergoing cemented femoral hip replacement for osteoarthritis were randomised to receive an Exeter (Howmedica Stryker), Ultima Tapered Polished Stem [TPS], Ultima straight stem [USS] (Johnson and Johnson) or Charnley Elite (Depuy/Johnson and Johnson) stem. RSA migration measurements were performed postoperatively and at 6,12,18 and 24 months post surgery using the UMRSA system. Results: Two signiþcantly distinct patterns of distal migration in the y direction (subsidence) were seen, compatible with previous studies. Tapered stems subsided rapidly by six months, Exeter 0.85mm (±0.15) UTPS 0.85mm (±0.15), stabilising by 2 years, Exeter 1.3mm (±0.35), UTPS 1.2mm (±0.25). The USS and Elite designs showed lower migrations of 0.1mm (±0.1) and 0.15 (±0.15) mm at six and 0.25mm (±0.15) and 0.35mm (±0.15) at 24 months. For migrations and rotations in other directions, differences were seen between prostheses with the same design concept. Whilst both the UTPS and Exeter exhibited posterior migration of the head, by 24 months this was expressed as a rotation about the transverse axis for the TPS and the axial axis for the Exeter. The Elite and USS differed in rates of posterior migration and varus tilt. Conclusions: Patterns of migration for stems with the same design concept may vary due to subtle differences in prosthesis shape. These variations produce a distinct migration Ç signature È for each stem.

Aims: To study prospectively the characteristic migration of four different cemented femoral stems using Radiostereometry.

Methods: 96 patients undergoing cemented femoral hip replacement for osteoarthritis were randomised to receive an Exeter (Howmedica Stryker), Ultima Tapered Polished Stem [TPS], Ultima straight stem [USS] (Johnson and Johnson) or Charnley Elite (Depuy/Johnson and Johnson) stem. RSA migration measurements were performed at postoperatively and at 6,12,18 and 24 months post surgery using the UMRSA system enhanced with locally developed software.

Results: Two significantly distinct patterns of distal migration in the y direction (subsidence) were seen compatible with previous studies. Tapered stems subsided rapidly by six months Exeter 0.85mm (+/−0.15) UTPS 0.85mm (+/−0.15) stabilising by 2 years Exeter 1.3mm(+/−0.35), UTPS 1.2mm(+/−0.25). The USS and Elite designs showed lower migrations of 0.1mm (+/−0.1) and 0.15 (+/−0.15) mm at six and 0.25mm(+/−0.15) and 0.35mm (+/−0.15) 24 months. For migrations and rotations in other directions differences were seen between prostheses with the same design concept. Whilst both the UTPS and Exeter exhibited posterior migration of the head, by 24 months this was expressed as a rotation about the transverse axis for the TPS and the axial axis for the Exeter. The Elite and USS differed in rates of posterior migration and varus tilt.

Conclusions: Patterns of migration for stems with the same design concept may vary due to subtle differences in prosthesis shape. These variations produce a distinct migration “signature” for each stem.

1. A case of chondromyxoid fibroma of the tibia is reported.

2. Initial removal by curettage was followed by regrowth of residual foci; these were removed by a second curettage three years later. Re-examination after a further three years shows no evidence of regrowth, and suggests that cure has been achieved.

3. Some histological features of the neoplasm are briefly described.