Approximately one-fifth of patients are not satisfied with total knee arthroplasty (TKA). Preoperative variables associated with poorer outcomes are severity and chronicity of pain and psychological disease, which may present as anxiety and depression. It is unclear whether this is constitutional or the result of knee pain. To address this, we explored the association of anxiety and depression with knee disability before and after TKA.

Forty patients undergoing TKA completed Hospital Anxiety and Depression Scale (HADS) and Oxford Knee Scores (OKS) preoperatively and at three and six months postoperatively. Both were elevated preoperatively and improved significantly post-operatively (P<0.001). The severity of preoperative anxiety and depression was associated with worse knee disability (coefficient −0.409, p=0.009). Postoperatively reduction in anxiety and depression was associated with improvement in knee disability after three (coefficient −0.459, p=0.003) and six months (coefficient −0.428, p=0.006).

The difficulty in interpreting preoperative anxiety and depression and the outcome of TKA is establishing whether they are the cause or effect of pain in the knee. As anxiety and depression improves with knee pain and function, this study suggests that knee pain contributes to the psychological symptoms and that a successful TKA offers an excellent chance of improving both.

Background

Venous thromboembolism deterrent (TED) stockings are recommended for all orthopaedic patients. Clinical evidence supporting their use is limited and the risk of DVT increases four-fold if pressure gradients are reversed. This study aims to investigate the efficacy of TED stockings and their application using pressure gradients as the outcome measure.

Resurfacing hip arthroplasty is a successful option for the treatment of the young and active patient with hip arthritis. However, it is complicated by femoral neck fracture and avascular necrosis, which result from devascularisation during surgery. Devascularisation maybe caused by thermal necrosis. Thermal necrosis of bone has been shown to occur in temperatures of 47°C and above. We investigated the temperatures generated during femoral head preparation to see if the temperatures reached were great enough to induce osteonecrosis.

Method: Eight patients with osteoarthritis underwent standard resurfacing hip arthroplasty through the posterior approach. From the first over-drilling of the femoral heads until the prosthesis was cemented in place the temperatures generated at the bone surface were recorded using an infra-red thermal imaging camera. Images were captured every 4 seconds as the operation was performed with no interference to the surgeon

Results: The maximum temperatures generated occurred during sleeve reaming at 88.4°C. Seven patients had a temperature recorded greater than 47°C. Removing the femoral caput with an oscillating saw had the highest mean temperature 62.2°C, followed by sleeve reaming (mean 48.7°C). Female patients had the lowest temperature rises and patients receiving the larger femoral prosthesis the greatest temperatures at the bone surface.

Conclusions: Heat generated during femoral head preparation exceeded 47°C in all but one case. Osteonecrosis secondary to thermal insult is likely to occur during femoral head preparation. Strategies need to be devised to decrease the temperatures generated during femoral head preparation.

Introduction: Resurfacing hip arthroplasty is a successful option for the treatment of the young and active patient with hip arthritis. However, it is complicated by femoral neck fracture and avascular necrosis, which may result from devascularisation during surgery. Devascularisation maybe caused by thermal necrosis. Thermal necrosis of bone has been shown to occur in temperatures of 47°C and above. We investigated the temperatures generated during femoral head preparation to see if the temperatures reached were great enough to induce osteonecrosis.

Method: Eight patients with osteoarthritis underwent standard resurfacing hip arthroplasty through the posterior approach. From the first over-drilling of the femoral heads until the prosthesis was cemented in place the temperatures generated at the bone surface were recorded using an infra-red thermal imaging camera. Images were captured every 4 seconds as the operation was performed with no interference to the surgeon

Results: The maximum temperatures generated occurred during sleeve reaming at 88.4°C. Seven patients had a temperature recorded greater than 47°C. Removing the femoral caput with an oscillating saw had the highest mean temperature 62.2°C, followed by sleeve reaming (mean 48.7°C). Female patients had the lowest temperature rises and patients receiving the larger femoral prosthesis the greatest temperatures at the bone surface.

Conclusions: Heat generated during femoral head preparation exceeded 47°C in all but one case. Osteonecrosis secondary to thermal insult is likely to occur during femoral head preparation. Strategies need to be devised to decrease the temperatures generated during femoral head preparation.

Introduction: Inadequate cementation of the acetabular component in hip replacement surgery leads to early aseptic loosening, the most common cause of revision. The optimum method of cementation has not been fully evaluated. This study aimed to determine the effect of the acetabular component flange on mean and peak pressure during component insertion.

Method: A 53mm deepened hemisphere was machined from aluminium. Pressure transducers were positioned at the rim, at 45 degrees, and at the base. Polyethelene acetabular components of different sizes and flange designs were mounted onto a materials testing machine and inserted at a constant rate into Palacos R cement within the aluminium hemisphere. Insertion was stopped at a pre-determined point when an even cement mantle was achieved. The same components were then tested without a flange. Each test was repeated six times. Output data from the transducers was analysed.

Results: Components with a flange create a mean pressure 6–18 times higher at the rim than those without a flange. At the base pressures are 2–4 times higher. A stiffer flange generates higher peak and mean pressures than a more malleable flange. Delaying insertion by one minute does not increase the pressures achieved unless a flange is used.

Discussion: These results strongly support the use of a flange to contain cement during insertion of the acetabular component. Unflanged components fail to achieve satisfactory mean or peak pressures, even if insertion is delayed. This is likely to result in poor cement penetration into bone and reduced longevity of interface fixation.

We have determined the 10 year life expectancy of 5,831 patients who had undergone 6,653 elective primary total hip replacements (THR) at a regional orthopaedic centre between April 1993 and October 2004.

Methods: We ascertained dates of deaths for all those who had undergone surgery during this period and constructed Kaplan Meier survivorship curves for these patients. Standardized mortality ratios were calculated by comparing this data with available UK mortality rates for the same age groups over the same time period.

Results: The mean age at operation was 73 with a male to female ratio of 2:3. Of those with 10 year follow up 29.5% had died a mean of 5.6 years after surgery. 10-year survivorship was 89% in patients under 65 years at surgery, 75% in patients aged between 65 – 74 years and 51% in patients over 75.

The standard mortality rates were significantly higher than expected for patients under 45 years, 20% higher for those between 45 and 64 years and progressively less than expected for patients aged 65 and over.

Discussion: By comparing our mortality curves with prosthesis survivorship curves from the most recent Swedish Arthroplasty Register results we were able to demonstrate that the survivorship of cemented hip arthroplasties exceeds that of the patients over the age of 60 in our area. As these prostheses are less expensive than their uncemented equivalents this suggests these are the prosthesis of choice in this age group.

We determined the 10 year life expectancy of 5,831 patients who had undergone 6,653 elective primary total hip replacements (THR) at a regional orthopaedic centre between April 1993 and October 2004. Using Hospital, General Practitioner (GP) and the local health authority’s records, we determined dates of deaths for all those who had undergone surgery during this period.

The mean age at operation was 73 (13–96) with a male to female ratio of 2:3. Of those with 10 year follow up 29.5% had died a mean of 5.6 (0–11.1) years after surgery. Using Kaplan Meier curves, 10-year survivorship was 89% in patients under 65 years at surgery, 75% in patients aged between 65 – 74 years and 51% in patients over 75.

The standardised mortality rates (SMR) were significantly higher than expected for patients under 45 years, 20% higher for those between 45 and 64 years and progressively less than expected for patients aged 65 and over.

The survivorship of cemented hip arthroplasties (derived from the Swedish Arthroplasty Register 2004) exceeds patients’ life expectancy in those over the age of 60 in our area suggesting that this is the procedure of choice in this population.

Introduction: Arthroplasty is the most effective management of displaced intracapsular femoral neck fracture. Hemiarthroplasty (HEMI) is associated with acetabular erosion and loosening in mobile active patients and total hip arthroplasty (THA) with instability.

We sought to establish whether HEMI or THA gave better results in independent mobile patients with displaced femoral neck fracture.

Method: Eighty-one patients were randomised into two groups. One arm received a modular HEMI, the second a THA using the same femoral stem. Patients were followed for a mean of three years after surgery.

Results: After HEMI, eight patients died, two were revised to THA and there is intention to revise three. One patient had a Peri-prosthetic fracture. Mean walking distance was 1.08 miles and Oxford Hip Score (OHS) 22.5. Twenty patients (64.5% of survivors) had radiological evidence of acetabular erosion.

After THA, three patients died, three dislocated, one required revision. Mean walking distance was 2.23 miles and OHS was 18.8. There was no radiological evidence of polyethylene wear

Patients with THAs after three years walked further (p=0.039) and had a lower OHS (p=0.033).

Discussion: HEMI is associated with a higher actual and potential revision rate than THA because of acetabular erosion, higher OHS after three years and shorter walking distances.

THA is a preferable option to HEMI in independent mobile elderly patients with displaced intracapsular femoral neck fracture.

The aim of this study was to determine the outcome of total hip arthroplasty, with regard to dislocation, at our unit.

1727 primary total joint arthroplasties and 305 revision total hip arthroplasties were performed between 1993 and 1996 at our unit. We followed up 1567 of the primary hip arthroplasties and 284 of the revision hip arthroplasties at 8 to 11 years post surgery. Patients were traced by postal questionnaire, telephone interview or examination of case notes of the deceased.

The dislocation rates by approach were: 23 out of 555 (4.1%) for the posterior approach, 0 out of 120 (0%) for the Omega approach and 30 out of 892 (3.4%) for the modified Hardinge approach.

58.5% of dislocations after primary total hip arthroplasty were recurrent. The mean number of dislocations per patient was 2.81.

8.1% of revision total hip arthroplasties suffered dislocation. 70% of these became recurrent. The mean number of dislocations per patient was 2.87. The vast majority of dislocations occur within 3 months of surgery.

To our knowledge this is the largest multisurgeon audit of dislocation after total hip arthroplasty published in the United Kingdom. The follow-up of 8 to 11 years is longer than most comparable studies.

Introduction and aims: Leg length discrepancy (LLD) after total hip arthroplasty (THA) has been associated with a number of complications. The aim of this study was to assess the influence of LLD on the outcome of THA by comparing patients’ perception and their Oxford Hip Score with their anatomical leg length. A secondary aim was to identify the site at which LLD was created intraoperatively.

Methods: LLD and hip function were assessed in 90 patients undergoing primary total hip arthroplasty before and 3 months after surgery. Hip function was measured by the Oxford Hip Score (OHS). We measured leg length on pre- and postoperative radiographs and the position of the centre of rotation and the stem length on the postoperative radiographs.

Results: Post operatively 62% of patients’ limbs were lengthened by a mean of 9 mm. This was perceived by 43% of the lengthened patients. The OHS in patients who perceived true lengthening was 27% worse than the rest of the population. In 98%, lengthening occurred in the femoral component. 20% perceived true shortening and their OHS was not affected.

Conclusion: The problem of LLD after THA is lengthening. Accurate placement of the femoral component and especially avoiding overlengthening could significantly reduce patients’ perception of this.

Introduction: Aseptic loosening is the main cause of revision in hip replacement surgery. Improved cementation techniques have reduced the rate of loosening of the femoral component, leaving the cemented acetabular cup as the major problem, with reported loosening rates as high as 25% at 12 – 15 years. The ideal method of acetabular cementation has not been fully evaluated.

Aim: To determine the ideal thickness of cement mantle to resist torsional forces.

Method: Mahogany blocks with a 54mm hemispherical hole were used to simulate an acetabular socket. Machined aluminium cups were created in 5 sizes (52mm to 44mm) to give a cement mantle that varied in size from 1mm to 5mm. Three 10mm keyholes were drilled in the blocks and appropriate-sized spacers were inserted to ensure the mantle was accurate and even. Silicone grease was used to prevent any micro-interlock between cement and wood. The cups were then cemented into the wooden blocks using vacuum-mixed Palacos R cement and left to cure in air for 7 days at 37 °C. The constructs were tested to failure using a servo-hydraulic testing machine. Each experiment was repeated six times.

Results: The stiffness of the cement mantle varied according to thickness as follows:

Discussion: A stiffer cement mantle will transfer more torque to the bone-cement interface, possibly leading to earlier loosening of the prosthesis. This biomechanical analysis suggests that surgeons should aim to achieve a mantle at least 2mm thick. There appears to be little further mechanical advantage gained if the mantle is increased in thickness beyond 4mm.

The rate of deep infection following primary joint replacement has reduced to below 1%, but the cost remains high. The surgical team is the most important source of bacteria causing infection. All surgical gowns are susceptible to penetration by these organisms, which may then spread to the wound via the surgeon’s hands or contact with wet drapes without ever being airborne.

There is insufficient clinical data on the penetration of bacteria through surgical gowns, in part due to the difficulty of in vivo measurement. A simple new method was developed, using petri dishes filled with horse blood agar that were attached to the outside of the gown material. This was used to assess bacterial penetration through disposable spun-bonded polyester gowns and re-usable woven polyester gowns during normal use.

There was a significant difference between the two gown types when tested in the axilla (p < 0. 05), the groin (p < 0. 05) and the peri-anal region (p < 0. 01), with the disposable gowns performing to a higher standard.

Re-usable gowns demonstrated significant variation in penetrability. This is most likely to be due to the number of laundering and sterilisation cycles that they had undergone. Unless the continued satisfactory performance of multiple-use gowns can be guaranteed, they may be unsuitable for use in orthopaedic implant surgery.

Aseptic loosening of the acetabular component is the main reason for revision hip arthroplasty surgery with loosening rates reported at 25% at 12–15years. The optimum method of acetabular preparation and cementation technique has not been fully evaluated. Clinical follow-up studies suggest multiple keyholes improve survival rates.

Keyholes increase penetration of cement and torsional resistance of the bone-cement interface. Some studies support the traditional three 1/2 inch keyholes other studies have shown multiple smaller holes improve stability. The optimum size and number of holes to provide the strongest fixation has yet to be determined.

Using an established 54mm diameter acetabular model, mahogany, three sizes of keyhole were tested-3x10mm holes, 12x5mm, and 48x2.5mm- the surface area of the defects created were the same in each group. The model acetabulum was filled with cement and a metal central bar inserted through which torque could be applied using an Instron machine. Six specimens from each group were tested. Three 10mm holes produced a significantly stronger resistance to torque when compared to 2.5mm (p≤0.017) and 5mm holes (p≤0.001). There was no significant difference between 2.5mm and 5mm holes (p≤0.139). Each addition of a further 10mm hole significantly increased the torque strength until the model was destroyed at six holes.

In laboratory testing larger key holes provide a stronger cement-acetabular interface.

Twelve patients undergoing total hip replacements were given 600mg linezolid as a 20min intravenous infusion along with conventional prophylaxis of 1gm cefamandole immediately before surgery. Routine total hip arthroplasty was performed and at timed intervals during surgery, samples of bone, fat, muscle and blood were collected for assay by HPLC analysis. Samples of haematoma fluid that formed around the operation site and further blood samples were also collected at timed intervals following the operation for assay. The penetration of linezolid into bone was rapid with mean levels of 9.1mg/L (95% CI: 7.7–10.6mg/L) achieved at 10min after the infusion, decreasing to 6.3mg/L (95% CI: 3.9–8.6mg/L) at 30min. Correcting for the simultaneous blood concentrations gave values for bone penetration of 51% at 10min, 60% at 20min and 47% at 30min. although the penetration of linezolid into fat was also rapid, mean levels and degree of penetration were approximately 60% of those seen in bone at 10min: 4.5mg/L (95%CI:3–6.1mg/L; penetration 27%) 20min: 5.2mg/L (95% CI:4–6.4mg/L; penetration 37%) and 30min:4.1mg/L (95% CI:3.3–4.8mg/L; penetration 31%). For muscle, the corresponding values were 10min: 10.4mg/L (95%CI:8.1–12.7mg/L; penetration 58%), 20min 13.4mg/L (95%:10.2–16.5mg/L; penetration 94%) and 30min 12mg/L (95% CI:9.2–14.8mg/L; penetration 93%). Mean concentration of linezolid in the haematoma around the operation site were 8.2mg/L at 6–8h and 5.6mg/L at 8–10h after the infusion and 7mg/L at 2–4h following a second 600mg infusion given 12h postoperatively.

We conclude that linezolid exhibits rapid penetration in bone, fat and muscle of patients undergoing hip arthroplasty to achieve levels in excess of the MIC for sensitive organisms (MIC of < _ 4mg/L); with therapeutic levels maintained in the drainage which surrounds the operation site for more than 16h. This pharmaco-kinetic profile is similar to those of agents currently used for the treatment of bone and associated soft tissue infections and suggests a role for linezolid in the management of such patients