Aims

Periprosthetic fracture (PF) after primary total hip arthroplasty (THA) is an uncommon but potentially devastating complication. This study aims to investigate the influence of cemented stem designs on the risk of needing a revision for a PF.

Pre-operative variables are increasingly being used to determine eligibility for total knee replacement (TKR). This study was undertaken to evaluate the relationships, interactions and predictive capacity of variables available pre- and post-operatively on patient satisfaction following TKR. Using nationally collected patient reported outcome measures and data from the National Joint Registry for England and Wales, we identified 22 798 patients who underwent TKR for osteoarthritis between August 2008 and September 2010. The ability of specific covariates to predict satisfaction was assessed using ordinal logistic regression and structural equational modelling. Only 4959 (22%) of 22 278 patients rated the results of their TKR as ‘excellent’, despite the majority (71%, n = 15 882) perceiving their knee symptoms to be much improved. The strongest predictors of satisfaction were post-operative variables. Satisfaction was significantly and positively related to the perception of symptom improvement (operative success) and the post-operative EuroQol-5D score. While also significant within the models pre-operative variables were less important and had a minimal influence upon post-operative satisfaction. The most robust predictions of satisfaction occurred only when both pre- and post-operative variables were considered together. These findings question the appropriateness of restricting access to care based on arbitrary pre-operative thresholds as these factors have little bearing on post-operative satisfaction.

Cite this article: Bone Joint J 2013;95-B:1359–65.

Background

Current analysis of unicondylar knee replacements (UKR) by national registries is based on the pooled results of medial and lateral implants. Using data from the National Joint Registry for England and Wales (NJR) we aimed to determine the proportion of lateral UKR implanted, their survival and reason for failure in comparison to medial UKR.

Background

Both surgeon and hospital volume influence patient outcomes following revision knee arthroplasty.

Introduction

High flexion knee arthroplasties have been designed to allow up to 155 degrees flexion and enable high flexion activities such as kneeling and squatting. To date randomised controlled trials have shown no difference in range of movement (ROM) between high flexion and standard designs.

Introduction

Following in-depth analysis of the market leading brand combinations in which we identified implant influences on risk of revision, we compared revision in patients implanted with different categories of hip replacement in order to find implant with the lowest revision risk, once known flawed options were removed.

Purpose

To determine how patient characteristics; health status and pre-operative knee function effect patient reported satisfaction and operative success following total knee replacement (TKR). We hypothesised that a number of patient factors would influence the reported levels of symptomatic improvement (success) and satisfaction and that these two outcomes would represent different aspects of the patient's perception of outcome.

Background

The most appropriate form of chemical thromboprophylaxis following knee replacement is a contentious issue. Most national guidelines recommend the use of low molecular weight Heparin (LMWH) whilst opposing the use of aspirin. We compared thromboembolic events, major haemorrhage and death after knee replacement in patients receiving either aspirin or LMWH.

Purpose

To examine how patients viewed the outcome of their joint replacement at least one year post surgery. Emphasis was placed on investigating the relative influence of ongoing pain and functional limitation on patient satisfaction.

Introduction

We have carried out a 15 year survival analysis of a prospective, randomised trial comparing cemented with cementless fixation of press-fit condylar primary total knee replacements.

Introduction

The purpose of this study was to establish whether men and women with a fragility hip fracture were equally investigated and treated for osteoporosis.

This study evaluates the effect of lower limb post-operative mechanical axis on the long term risk of revision surgery following primary total knee arthroplasty (TKA). The study is relevant because many recent clinical trials have evaluated the optimal surgical technique for accurately aligning components in TKA, despite little evidence that alignment may effect the long-term clinical outcome.

The data used in this study was collected prospectively as part of a randomized control trial comparing the long term survival of cemented versus uncemented TKA. The trial included 501 press-fit condylar posterior cruciate ligament-retaining prostheses performed by the senior author (PJG) or under his direct supervision. The post-operative mechanical axis alignment of the lower limb was measured following TKA using standard AP weight-bearing long leg alignment radiographs. A comparison was made between a well-aligned group with a mechanical axis alignment within 3° of neutral; and a poorly-aligned group whose mechanical axis alignment deviated greater than 3° from neutral. Survival analysis used revision surgery, with exchange of any of the three originally inserted components (femoral, tibial, polyethylene insert), as the endpoint.

There was no loss to follow-up in this study. The minimum follow-up of TKAs in this study was 5.8 years. In the population of TKAs that were followed up at 10 years, 6% (17/270) required revision surgery. There was a significant difference in the rate of revision surgery between the well-aligned group 5% (11/227) and the poorly-aligned group 14% (6/43 p< 0.05)

This study shows that post-operative lower limb mechanical axis alignment is an important determinant of the need for revision surgery at 10 years. Surgeons performing TKA should pay particular attention to the placement of the tibial and femoral components, so that a mechanical axis within 3° of neutral is achieved.

Background: Functional outcome and patient satisfaction after total knee arthroplasty can be variable. Up to 20% of patients have been reported to not be entirely happy with their knee replacement. Psychological factors, in particular illness perception – a patient’s beliefs about their illness – have been found to predict recovery from a range of conditions. Few studies have examined their impact within the orthopaedic context.

Aim: The aim of this study was to investigate the impact of psychological factors, including illness perception, anxiety and depression, on postoperative recovery and functional outcome after total knee arthroplasty.

Patients and Methods: 100 patients from two centres, who underwent a primary total knee arthroplasty for osteoarthritis between 2004 and 2006, took part in this prospective cohort study.

Before surgery patients were asked to complete a psychological questionnaire consisting of Revised Illness Perception Questionnaire (IPQ-r), Hospital Anxiety and Depression Scale (HADS) and Recovery Locus of Control (RLOC). Knee function was assessed preoperatively, at six weeks and one year using Oxford Knee Score (OKS) and range of motion (ROM).

Results: The mean OKS improved significantly at six weeks and further at one year. The mean ROM showed little change in the first six weeks, but was significantly improved at the one-year follow-up.

The psychological factors Consequences, Illness Coherence, Emotional Representation and HADS Anxiety showed a statistically significant correlation with the OKS at six weeks, the factors Consequences and HADS Anxiety and HADS Depression with the OKS at one year. We found no correlation with range of motion at six weeks, but ROM at one year was statistically significantly correlated with the factors Consequences and HADS Depression.

This indicates that patients who believed that their illness had less impact on their personal lives and patients with lower scores on the anxiety and depression scale showed a lower OKS and higher ROM at one year, indicating a better functional outcome.

Hierarchical regression analysis showed that, after controlling for demographics and baseline scores, the factor consequences explained 7% of the variance in ROM at one year. HADS Anxiety and Depression had a significant impact on OKS and accounted for 13.7% of the variance of OKS at one year.

Discussion: Recovery from TKA surgery can be difficult to predict. This study showed that functional outcome can be significantly influenced by psychological factors. These should be taken into account when considering patients for TKA surgery. Improving patient education, looking at home environment and social network as well as addressing anxiety and depression may help to improve overall outcome after TKA surgery.

We report the 15 year follow-up of displaced intra-articular calcaneal fractures from a randomised controlled trial of conservative versus operative treatment. Of the initial study, 46 patients (82%) were still alive and 26 patients (57%) agreed to review.

The clinical outcomes were not different between operative versus conservative treatment. American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scale: p = 0.11; Foot Function Index (FFI): p = 0.66; and calcaneal fracture score: p = 0.41. The radiological outcomes also were not different between both groups. Böhler’s angle: p = 0.07; height of calcaneum: p = 0.57; and grade of osteoarthritis of the subtalar joint: p = 0.54. There was no correlation between Böhler’s angle and the outcome measures in either group.

The results of this 15 year follow-up of displaced intra-articular calcaneal fracture randomised controlled trial demonstrate similar findings to those at one year follow-up.

We report the results of a prospective randomised controlled clinical trial assessing the radiosterophotogrametric analysis (RSA), clinical and radiological performance of a metal backed and an all-polyethylene tibial cruciate retaining, condylar design, PFC-TKA up to twenty four months.

65 patients were recruited, of which 41 patients were randomised. There were 20 metal backed and 21 all-polyethylene. None were lost to follow-up. There were no significant inter-group demographic differences. We found a significant increase in SF-12 and Oxford knee scores after surgery in both groups. No significant difference was found between the groups in the RSA, SF-12, Oxford Knee score, radiological alignment and range of movement at 6, 12 or 24 months. At 2 years one metal backed implant showed translational migration > 1mm. No all polyethylene implant migrated > 1mm. Further analysis identified possible progressive subsidence of the metal backed implants compared to all-polyethylene implants, although the magnitude of this difference was very small.

We conclude that in the uncomplicated primary total knee arthroplasty, all polyethylene PFC-_ tibial prostheses had equivalent performance to the metal backed counterpart, using RSA as the primary assessment instrument at 24 months. We found no differences between the two designs as assessed by the secondary instruments: SF-12, Oxford knee score, alignment and range of movement at 24 months. Should half of all primary total knee replacements performed in the UK receive an all-polyethylene tibial implant, the estimated annual cost saving would be 21 million pounds per annum.

The aim of this study was to determine whether there is a difference in the functional outcome between fixed and mobile bearings in total knee arthroplasty.

120 patients were randomized (computer generated) to receive either a fixed or mobile bearing P.F.C. Sigma total knee replacement. 96 patients were needed to detect a 20° difference in range of motion (ROM) with a significance level of 0.05 and a test power of 0.97. Oxford knee score (OKS) and ROM were assessed independently before and one year after surgery.

Mean ROM and Oxford knee score before and at one year after surgery for both groups are shown as preliminary results for 70 patients (follow-up expected to be completed by March 2006):

There is no statistically significant difference in the mean ROM at one year and in change in ROM between the two groups (p=0.53 and p=0.21 respectively). The findings were similar for Oxford Knee Score at one year and change in Oxford Knee Score (p=0.45 and p=0.82). There was no early aseptic loosening in either group.

The one year results suggest that there is no significant difference in functional outcome measured as ROM and Oxford Knee Score between the two types of bearing. Further follow-up will be carried out to detect any differences in the long term outcome.

To identify mechanisms of failure in plate and nail fixation in proximal humerus fractures. 5% of the proximal humerus fractures need surgical fixation, which is carried out, principally, by open reduction and internal fixation or closed reduction and intramedullary nailing. Fixation failure remains a problem. This study answers the mode of failure of these implants regardless of the fracture personality. In-vitro testing of proximal humerus fixation devices was undertaken in 30 simulated osteoporotic bone models. Fracture-line was created at the surgical neck of humerus in all samples and fixed with five fixation devices; three plating and two nailing devices. The samples were subjected to failure under compression and torque. Failure was achieved in all models. Three failure patterns were observed in torque testing:

The two conventional plates Cloverleaf and T-plate behaved similarly, failing due to screw pull-out from both the proximal and distal fragment with a deformed plate.

The failure mode is dependent on implant properties as well, independent of the fracture personality. It is important to recognise the potential points of failure (proximal or distal fragment) when making the choice of implant to avoid fixation failure.

Aim: To compare of strength of constructs using the newer and part specific nail systems: Polarus and European Humeral Nail with that using PHILOS and Conventional plate systems in a simulated 2-part fracture of proximal humerus, in an osteoporotic bone model.

Materials and Methods: A Biomechanical laboratory study was undertaken. Third generation composite Humerus model was used, with short e-glass epoxy fibres forming cortex and polyurethane cancellous core. Low-density polyurethane core (1.2gm/cc) was used to simulate an osteoporotic model. Osteotomy at surgical neck of humerus was carried out to create 2-part fracture of proximal humerus. Samples were fixed using one of the implants- the Polarus nail, the European Humeral Nail, PHILOS Plate, Clover Leaf Plate or T-Plate. Following fixation samples were placed in a custom made jig to fix proximal and distal ends without interfering with implants and osteotomy site. All samples were subjected to cyclical torque, torque to failure, cyclical compression and Compression loading to failure.

Results: The two Nail systems that are specifically designed for fixation of proximal humerus fracture provided significantly better fixation in all the test modalities. PHILOS construct shows less plastic deformation in cyclical torque and cyclical compression when compared to the other plates but the 2 nail systems were far superior. Locking screws did not ‘back off’ in any of the experiments involving the Polarus, European Humeral Nail and PHILOS construct, however ordinary screws used with the conventional plates did back off both in ‘torque and compression’ testing.

Conclusions: Polarus and European Humeral Nail constructs provide better stability in torque and compression as compared to PHILOS, which in turn is a more stable construct in comparison to conventional plating devices.

Background: The incidence of proximal humeral fractures is increasing with time. There is continuing debate about the indications for surgical intervention for this relatively common injury. Baseline data on functional outcome is essential in order to study the effect of surgical intervention. Functional outcome scores provide reliable and valid judgments of health status and the benefits of treatment. During our preparation of a study proposal on this topic to the Health Technology Assessment Program recently, we noted the lack of such data on outcome scores in the current literature.

Aim: To assess the functional outcome using the Constant and Oxford scores in patients treated conservatively for proximal humeral fractures.

Methods: We prospectively studied 103 consecutive patients who were treated conservatively for proximal humeral fractures. Patient demographics, fracture type (Neer), hand dominance and comorbidity were recorded. Constant and Oxford shoulder scores were recorded 3 and 12 months post injury.

Results: The average Constant shoulder score for males was significantly higher (better outcome) and the Oxford shoulder score significantly lower (better outcome) as compared to females. The scores were not affected by hand dominance. Although the raw scores tended to be worse with 3 or 4 part fractures the difference in the mean scores between the various Neer fracture types did not reach convential levels of significance.

A trend towards lesser degrees of improvement in the outcome scores was noted with increasing age. The degree of improvement in the outcome scores was not affected by sex, limb dominance or fracture type (Neer’s classification).

Conclusion: This study indicates the average behaviour of the Constant and Oxford scores with conservative treatment of proximal humeral fractures. This data should help with sample size and power calculations when studying interventions for this injury. We hope that this data will provide a baseline to help inform future study designs on proximal humeral fractures.

Aims: To ascertain the efficacy of viscosupplementation with Supartz intra-articular knee injections when used in the absence of a specific protocol for its use.

Methods: Retrospective cohort study using data from a dedicated injection clinic, patient case notes and knee radiographs. Patients received the therapy in the absence of a protocol for its use. Patient’s age, gender, symptoms, walking ability, presence of deformity, medication history, previous injection or surgical intervention, physiotherapy, co-morbidity, date of presentation, delivery of course of supartz injections and indication were recorded. Knee radiographs were analysed using Kellgren and Lawrence grading system. Pain relief and avoidance of surgical intervention (when surgery was an option) were the outcome measures.

Results: 965 intra-articular injections in 193 courses of supartz therapy were given in 143 patients. 45.6% were male and 54.4% were female patients. At presentation, 33.2% patients were able to walk < 1/2 a mile, 35.2% patients 1/2-1 mile and 31.6% > 1 mile. Radiological assessment (using Kellgren and Lawrence grading) showed 2 cases with stage 1 disease, 83(43%) with stage 2, 102(52.3%) with stage 3, and 6 cases with stage 4 disease. The medial compartment was involved in 185 cases (95.9%), the lateral compartment in 44 (22.8 %) and patellofemoral joint (PFJ) was involved in 122 (63.2 %).

Pain relief was obtained in 84/193 cases (43.5%). In 122 cases where the aim was to avoid surgery, this was achieved in 52 cases (42.6%). Success rate decreased with increasing severity of disease (Fisher’s Exact test; p< 0.01). Only 25/122 cases with PFJ involvement had pain relief (21%), compared to 59/71 cases without PFJ involvement (83%), (Chi squared test; χ 2(1)=71.57, p< 0.01). Younger age (< 60 years) is a poor prognostic factor (Chi squared test; χ2(1)= 5.86, p=0.02).

Conclusions: Younger patients and those with PFJ involvement and advanced disease are unlikely to benefit from Supartz intra-articular injection. We consider it inappropriate to use this therapy in the absence of a protocol for its use.

Aims: Does PHILOS (Proximal Humeral Internal Locking system) construct provides better þxation than Clover leaf plate and T-plate in a simulated 2-part fracture of proximal humerus, in an osteoporotic bone model?Materials and Methods: Biomechanical laboratory study. Third generation composite Humerus model was used, with short e-glass epoxy þbres forming cortex and polyurethane cancellous core. Low density polyure-thane core (1.2gm/cc) was used to simulate an osteoporotic model. Osteotomy at surgical neck of humerus was carried out to create 2-part fracture of proximal humerus. Samples were randomised to receive one of the implants. Following þxation samples were placed in a custom made jig to þx proximal and distal ends without interfering with implants and osteotomy site. All samples were subjected to cyclical torque, Torque to failure, Cyclical compression and Compression loading to failure. Results were entered in a database. Results: PHILOS provided signiþcantly better þxation in ÔTorque to failureñ experiment. PHILOS construct shows less plastic deformation in cyclical torque and cyclical compression. Locking screws did not Ôback offñ in any of the experiments involving PHILOS construct, however ordinary screws did back off both in Ôtoque and compressionñ testing. Conclusions: PHILOS construct provides better stability in Torque and compression as compared to conventional plating devices, in an osteoporotic bone model.

The Department of Health and the Public Health Laboratory Service established the Nosocomial Infection National Surveillance Scheme (NINSS) in response to the need to standardise the collection of information about infections acquired in hospital. This would provide national data that could be used as a ‘benchmark’ by hospitals to measure their own performance. The definition of superficial incisional infection (skin and subcutaneous tissue), set by Centers of Disease Control (CDC), should meet at least one of the following criteria: I: Purulent drainage from the superficial incision. II: The superficial incision yields organisms from the culture of aseptically aspirated fluid or tissue, or from a swab, and pus cells are present. III: At least two of the following symptoms and signs of inflammation: pain or tenderness, localized swelling, redness or heat, and a. the superficial incision is deliberately opened by a surgeon to manage the infection, unless the incision is culture-negative or b. clinician’s diagnosis of superficial incisional infection.

This study assessed the interobserver reliability of the superficial incisional infection criteria, set by the CDC, in current practice.

The incisional site of 50 consecutive patients, who underwent elective primary joint arthroplasty (Hips & Knees), were evaluated independently by four observers. The most significant results of the study I: All four observers achieved absolute agreement (kappa=1) for Purulent wound discharge and clinical diagnosis of wound infection. II: The four observers obtained good agreement for pain criteria (kappa=0.76, III: There was significant disagreement (fair to poor) between all four observers for the following criteria: Localized swelling (kappa=0.34), Redness (kappa=0.33) and tenderness (kappa = 0.05).

This is the first study to assess the reliability of the criteria, as set by the CDC and recommended by NINSS, for the diagnosis of superficial incisional infection and shows the Criterion III is not reliable and we recommend it should be revised. Failure to do so could lead to inaccurate statistics regarding hospital wound infection and detrimental effect on hospital trusts in the setting of league table.

The National Institute for Clinical Excellence (NICE), in its “Guidance on the Selection of Prostheses for Primary Total Hip Replacement”, states that a revision rate of 10% or less at ten years should be regarded as the “benchmark” in the selection of prostheses for primary Total Hip Replacement (THR). This paper presents the results of such a study for primary Charnley THR. Methods: All patients undergoing primary Charnley THR during 1990 were prospectively registered with the Trent Regional Arthroplasty Study (TRAS). During 1990, 1198 Charnley THRs were performed on 1152 patients, under the care of 56 consultants, in 18 National Health Service and 6 private hospitals. The cohort contains 39.0% male and 61.0% female patients, with an average age at operation of 69.1years (21–103 years), 19.1% being less than 60 years. At 10 years all surviving patients at 5 years were registered with the ONS to ascertain living patients. These patients were contacted by letter to determine whether or not their THR had been revised. The status of the THR, for non-responding patients, was determined by contacting the patient’s GP through the Contractor Services Agency (CSA). The endpoint was defined as revision surgery to replace an original implant component. Results: At 10 years, the recipients of 438 THRs had died. The recipients of 89 THRs did not respond to the questionnaire at ten years. Implant status at ten years, in living patients was known for 671 of 760 (88.3%) THRs. The ten-year crude revision rate was 44 out of 1198 (3.7%) and cumulative survival rate was 95.5% (95% CI, 93.6% – 96.9%).

Conclusion: This is the first study to assess the survivorship at 10 years for primary Charnley THRs performed in the ‘general setting’ of the NHS as opposed to specialist centres and shows a result well within the NICE benchmark.

Cementless fixation for total knee arthroplasty (TKA) has been proposed as an alternative to cemented for several reasons, of which the most important is the possibility of increased survival. The purpose of this study was to compare the ten-year survival of TKA in a unique prospective randomised trial of cemented versus cementless fixation.

A consecutive series of patients was randomised to undergo either cemented or cementless Press-Fit Condylar (PFC®) TKA. There were 219 patients (277 TKA) in the cemented group and 177 (224 TKA) in the cementless group. There were no significant differences in age, gender or diagnosis between the two groups.

A single surgeon (PJG) performed or directly supervised all operations. The prosthesis used in all cases was the posterior-cruciate-retaining PFC® knee replacement system. Independent clinical review was performed at six months, annually until five years, and finally at ten years after surgery. Using revision surgery as the end-point, logrank analysis was used to compare the ten-year survival of the two groups.

The mean interval of follow-up was 6.3 years (range, 2.0–11.7). At the last review, 104 patients (138 TKA) had died, without need for revision. All patients were traced and there was no loss to follow-up. In the cemented group, seven arthroplasties were revised; five for infection and two for exchange of polyethylene inserts. Ten-year survival was 96.5% (95% CI, 90.9–98.7%). In the cementless group, six arthroplasties were revised; three for aseptic loosening, one for infection, one for instability and one resizing for anterior knee pain. The ten-year survival was 96.6% (95% CI, 89.6–98.9%). There was no significant difference in the survival of the two groups.

The long-term survival of cementless PFC® TKA is not significantly different from their cemented counterparts. The use of less expensive cemented implants, therefore, can make a significant impact on health resource planning.

To establish whether there were features present on the initial post-operative radiographs of total hip replacements (THR) predictive of aseptic loosening.

Our data was derived from the Trent Regional Arthroplasty Study (TRAS) which is the only hip register of its kind in the country. The TRAS commenced in 1990 and has recorded clinical and operative details of all THRs in the region.

Our current study was concerned with a cohort of grossly loose THRs, identified from the five-year follow up of those patients who had undergone THR in 1990. Our cohort are those which failed specifically due to aseptic loosening and comprises those revised or listed for revision as well as a number of previously undiagnosed cases.

The post-operative radiographs were analysed, recording the following: (1) number, width and location (Gruen zone) of radiolucencies at both cement-bone and cement-prosthesis interfaces; (2) presence of stem-cortex contact; (3) width of the cement mantle in each Gruen zone; and (4) Barrack cementation grade.

Occasionally, if the initial post-operative radiograph was of poor quality, then further information was gained from the next available ones (usually at six weeks) to improve accuracy.

Comparisons were made with 60 control hips randomly generated from the same 1990 cohort but which had not failed.

Chi-squared tests were used to test the probability of obtaining the observed data by chance and odds ratios were calculated to describe relative risk of failure for different risk factors.

Hips with inadequate cementation grades (C and D) had a 9.5 times greater risk of failure compared to those with adequate cementation grades (A and B) [p< 0.0001].

We have demonstrated that the grade of cementation has a major effect on the probability of failure. This emphasises the importance of good cementing, which is particularly relevant in this era of clinical governance where there is greater accountability on the surgeon for adequate performance.

Cementation is an important part of arthroplasty operations. Recent publication of results of Charnley total hip replacement found a rate of early aseptic loosening of 2.3% at 5 years following surgery across a NHS region. There are possibly many reasons for early loosening but precise reasons are still not fully understood, however, it is felt that cementation technique is very important. There seems to be a number of factors involved such as cement mixing techniques and conditions, physical properties of the cement, cementation and surgical techniques, bone-cement interface as well as bone- prosthesis interface. The purpose of this study was to evaluate the effectiveness of the clinical environment in producing bone cement of predictable mechanical and physical properties, and how those properties compare with published data. The investigation compared samples of bone cement, taken from material prepared and used in surgery with cement samples prepared under controlled laboratory conditions and in accordance with ISO materials testing standards.

During 2000–01, 10 total hip replacements were selected for study. All operations involved the use of CMW1 (DePuy) radio-opaque cement, which was mixed using the Vacumix system. In this cohort, all femoral cementations were performed using an 80g cement mix. After careful preparation of the femoral canal, the scrub nurse mixed the cement in accordance with the manufacturer’s instructions. The cement was introduced into the femoral canal, via a nozzle, using the cementation gun and a pressurizer. Following introduction of cement into the canal, the nozzle and cement contained within, was broken off the gun distal to the pressurizer. Once cured, the cement samples were removed from the nozzle, sectioned, and mechanically tested. Due to this novel sample preparation procedure, the tested cement was expected to exhibit mechanical and physical properties characteristic of the cement present in the femoral canal. Samples of CMW1 (Vacumixed) of similar mass and aspect ratio were produced within the laboratory, in accordance with the manufacturers mixing instructions. PMMA bone cement is a brittle, glassy polymer that is susceptible to stress raisers, such as pores, which can reduce the load carrying ability, which in vivo is predominantly compressive in nature. Published mechanical properties of PMMA bone cement vary somewhat, reflecting the dependence of properties on flaw distribution. The density, which provides a measure of porosity, hardness and ultimate compressive strength of the cement samples was measured and compared.

The surgical samples were found to be very consistent in compressive strength (121 ± 6 MPa), density (1.20 ± 0.02 gcm⁻³) and hardness (23.2 ± 1.6 VHN) and closely matched the mechanical properties of the cement mixed in the laboratory.

This study suggests that for the studied cement and mixing regime, the clinical environment is capable of producing a well-controlled cement product that has reproducible and predictable mechanical properties. Further, the novel sample preparation procedure used suggests that the cement within the femoral cavity should demonstrate equally predictable, mechanical and physical properties.

The early diagnosis of aseptic loosening of a total hip replacement by plain radiography, scintigraphy and arthrography has been shown to be unreliable. It has been suggested that it may be possible to distinguish between a secure and a loose prosthesis using a vibration technique. We have assessed the use of this technique in vitro using models of early and late loosening. Late loosening with an unstable prosthesis can be reliably detected by vibration analysis, but this method was shown to have a very poor diagnostic sensitivity in early loosening when there is no obvious prosthetic instability.

We report a randomised prospective trial of the early results of three types of treatment for displaced intracapsular hip fractures. We used a questionnaire sent to patients at about six months (Nottingham Health Profile, NHP) in addition to clinical assessments. There was a 67.4% usable response to the questionnaire, similar to that in other studies using the NHP. There were more responders from younger patients, those walking independently before injury and those with higher mental test scores on admission. In the younger group (65 to 79 years) we found a trend for better scores in most NHP indices after the use of a bipolar prosthesis rather than a unipolar prosthesis or internal fixation, particularly for social function, pain and physical mobility. Postal assessment using the NHP gave a satisfactory response rate even in the elderly, and can provide an extra assessment to complement or replace hospital follow-up in some circumstances.

We compared the reoperation rate after internal fixation for minimally displaced or impacted intracapsular fractures of the femoral neck in patients aged 80 years and above with that in similar patients aged 65 to 79 years. We also compared the results of internal fixation with those of hemiarthroplasty for displaced intracapsular fracture in an age- and sex-matched group of elderly patients. We found that a significantly greater proportion of the older patients treated by internal fixation required reoperation than either the younger group or the age-matched group treated by hemiarthroplasty. Our results indicate that internal fixation may not be the best treatment for extremely elderly patients with minimally displaced or impacted intracapsular fractures of the femoral neck.

We report a prospective trial of 66 patients with intraarticular fractures of the calcaneum. All fractures were assessed by CT. Patients with displaced fractures were randomised to receive either conservative (n = 31) or operative treatment (n = 25). Undisplaced fractures (n = 10) were treated conservatively. Operation involved open reduction of the posterior subtalar joint, and fixation with Kirschner wires. All 66 patients were reviewed at a minimum of one year (mean 23 months). After conservative treatment the undisplaced fractures had slightly better results than the displaced fractures. There was no significant difference in outcome between the operatively and the conservatively treated displaced fractures. We have also documented prospectively the natural history of the injury, which is of use in assessing prognosis for both clinical and medicolegal purposes.

We report the results of a randomised trial to determine the effects of skin traction on 252 patients awaiting surgery for fractures of the proximal femur. They were allocated randomly to be nursed free in bed or to receive Hamilton-Russell skin traction. No differences were found between the groups in terms of pain suffered, analgesia required, frequency of pressure sores or ease of operation. The application of skin traction to patients with fractures of the upper femur is time-consuming and we recommend therefore that its routine use should be discontinued.

The changes in serum adjusted ionised calcium and parathyroid hormone (PTH) were prospectively studied in 32 patients with isolated tibial fractures, treated conservatively. We measured serum albumin, adjusted total calcium, phosphate, pH, adjusted ionised calcium and PTH at intervals until the fractures had healed. The mean ionised calcium adjusted for pH fell within 24 hours of injury, and then rose to a peak at between four and six weeks. These changes cannot be explained by changes in serum pH or PTH. The restoration of normal ionised calcium levels after fracture coincided with the period when the callus was being calcified. Analysis of the changes in ionised calcium, phosphate and PTH suggests that PTH levels alter in response to changes in ionised calcium levels. PTH is highest immediately after fracture and lowest, often not recordable, at six weeks. The cause of the changes in the ionised calcium level has yet to be elucidated.

We have studied the incidence of fractures of the proximal femur in one English county from 1968 to 1991. Numbers have increased steadily, but the age-specific incidence has remained relatively unchanged since 1981. The increase is due to the rise in the population most at risk; this is likely to continue causing a 20% increase in demand for treatment by the year 2000. Suitable allocation of resources must be planned.

We have studied the radiographic and CT features of 120 displaced intra-articular fractures of the calcaneum in order to define the pathological anatomy. In 96% of cases, the CT scans identified three main fragments: sustentacular, lateral joint and body. The sustentacular fragment was often rotated into varus, the lateral joint fragment into valgus and the body fragment impacted upwards, in varus and displaced laterally. The displacement of these fragments varied according to which of three fracture types was present, as defined by the composition of the fractured lateral wall of the calcaneum. In type 1 it was formed by the lateral joint fragment alone; in type 2 by both body and lateral joint fragments; and in type 3 by the body fragment alone. Fracture fragment displacement differs from that previously described, in that true uniform depression of the lateral joint fragment is rare.

We studied the changes in plasma viscosity and C-reactive protein to establish normal values after total hip or knee arthroplasty. Viscosity decreased from 1.68 (+/- 0.017) to 1.57 (+/- 0.014) on the first postoperative day and thereafter rose to 1.60 (+/- 0.019), 1.75 (+/- 0.015), and 1.74 (+/- 0.011) on the third, seventh and fourteenth days respectively. Six to eight weeks after operation it had returned to pre-operative levels. A viscosity above the upper limit of the laboratory range, obtained more than two months after operation, may be considered as abnormal. The C-reactive protein level increased significantly on the first postoperative day and then decreased from a peak on the second day, attaining nearly normal levels at six to eight weeks after operation. It may be a more sensitive indicator of deep postoperative infection than plasma viscosity.

We measured pressures in the anterior and deep posterior compartments continuously for up to 72 hours in 20 patients with closed fractures of the tibial shaft treated primarily in plaster casts. All were examined independently after periods of three to 14 months. Pressures above 40 mmHg occurred in seven (35%) and above 30 mmHg in 14 (70%). No patient had the symptoms of compartment syndrome during monitoring. Abnormalities at review did not correlate with the maximum consecutive time periods during which the compartment pressures were raised. Thus, in the absence of symptoms the monitored pressures did not relate to outcome. Routine monitoring in this type of patient is therefore of doubtful benefit.

Immobilisation of the thumb is widely believed to be important in the management of fractures of the carpal scaphoid. To assess the need for this, we randomly allocated 392 fresh fractures for treatment by either a forearm gauntlet (Colles') cast, leaving the thumb free, or by a conventional 'scaphoid' plaster incorporating the thumb as far as its interphalangeal joint. In the 292 fractures which were followed for six months, the incidence of nonunion was independent of the type of cast used.

We studied 50 patients with fractures of the femoral neck, 33 intracapsular and 17 extracapsular. Intraosseous pressure was measured by a transducer within the bone to quantify blood flow, and intracapsular pressure by a needle introduced into the joint space. The mean intracapsular pressure was lower in the extracapsular fractures. In these, the mean intraosseous pressure in the femoral head was unchanged by aspiration of the joint. However in the intracapsular fractures aspiration produced a significant decrease in intra-osseous pressure and an increase in pulse pressure within the femoral head. The results suggest that aspiration of intracapsular haematoma produced an increase in femoral head blood flow by relieving tamponade.

We report a prospective randomised trial comparing Keller's arthroplasty and arthrodesis of the first metatarsophalangeal joint for the management of symptomatic hallux valgus and hallux rigidus in the older patient. In 81 patients (110 feet), with a minimum of two years follow-up, both procedures gave a similar degree of patient satisfaction and symptom relief. The incidence of metatarsalgia was also similar. As there were no obvious advantages to arthrodesis, and since six out of 50 arthrodesed toes required revision, we suggest that Keller's arthroplasty is the better operation in these patients.

Twenty observers reported independently on the presence or absence of a fracture of the scaphoid on 60 sets of radiographs; these included initial and 2- to 3-week views in patients in whom the outcome was known, normal scaphoids and random copies of these. Analysis of variance of the accuracy of observations revealed that the 2- to 3-week radiographs did not improve diagnostic ability and that this was independent of the experience or seniority of the observer. For normal radiographs, 20% of the observations reported a fracture. Reproducibility of opinion improved with experience but this did not help with accuracy. Radiographs without accurate clinical observation should not determine the management of the suspected scaphoid fracture.

In 15 consecutive patients with slipped capital femoral epiphysis we recorded height, weight and skeletal maturity. Sexual maturity was assessed clinically and biochemically, and Harris's hypothesis that there is an increased ratio of serum growth hormone to oestrogen was tested in comparison with 15 age and sex matched controls. We found no difference in skeletal or sexual maturity between the groups, or any overt endocrine abnormality in the patients. However almost half the patients with slipped epiphysis were over the 90th weight percentile, suggesting that mechanical factors such as obesity are more important aetiologically than endocrine abnormalities.

One hundred consecutive closed fractures of the adult tibial shaft treated by closed methods were surveyed prospectively in order to observe their natural history. The fractures were analysed with regards to speed of healing and the influence of age, sex, causal force, radiological morphology and concurrent fibular fracture. At 20 weeks 19 fractures had not yet united, but 15 of these had united by 30 weeks with conservative treatment alone. The remaining four cases were operated upon because no further progress in healing was anticipated. These findings suggest that, with regard to healing, open reduction and internal fixation is rarely justified in closed adult tibial shaft fractures.

Inter-observer agreement and reproducibility of opinion were assessed for the radiographic diagnosis of union of scaphoid fractures on films taken 12 weeks after injury. Weighted kappa statistics were used to compare the opinions of eight senior observers reviewing 20 sets of good quality radiographs on two occasions separated by two months. There was poor agreement on whether trabeculae crossed the fracture line, whether there was sclerosis at or near the fracture and on whether the proximal part of the scaphoid was avascular. As a consequence, agreement on union also was poor; it appears that radiographs taken 12 weeks after a scaphoid fracture do not provide reliable and reproducible evidence of healing.

Thirty-six patients with 39 fresh fractures of the calcaneus were investigated by standard radiography and by computerised tomography. It was found that the size and disposition of the fracture fragments and the degree of involvement of the posterior facet of the subtalar joint were more clearly shown by CT scanning. We recommend this technique for assessment and particularly for pre-operative planning.