Abstract

Abstract

Patients with knee prosthetic joint infection (PJI) frequently receive one- or two-stage revision. To explore the feasibility of a randomised controlled trial (RCT) comparing methods, we analysed a UK registry, interviewed patients and surgeons, systematically reviewed literature, held a consensus meeting, and assessed progress of an RCT in hip PJI. In 2014, in England and Wales, knee PJI was treated with one- or two-stage procedures in 19% and 71% of patients respectively. Between 2007 and 2014, use of one-stage procedures doubled and, in major centres, up to 42% of treatments were one-stage. We conducted in-depth interviews with 16 patients with knee PJI and 11 surgeons performing one- or two-stage revision. Patients considered randomisation acceptable with appropriate counselling and, depending on infecting organisms and health status, surgeons would randomise treatments. In meta-analysis, two-year re-infection rates in 10 one-stage series (423 patients) and 108 two-stage series (5,129 patients) were 7.6% (95%CI 3.4,13.1) and 8.8% (7.2,10.6) respectively. In a series of patients with knee PJI, surgeons from 2 major centres considered 6/15 patients eligible for either treatment, with 4 more potentially eligible after treatment of soft tissue infection. In an ongoing RCT of surgical treatment of hip PJI, 116 patients have been randomised at 14 centres in 3 years. Randomising patients with PJI is feasible but, as knee PJI is uncommon, a multicentre RCT would be required. Based on WOMAC score outcome and appropriate assumptions on eligibility and acceptability, 170 patients would need to be randomised over 4 years at 14 major centres.

A key theme of the GIRFT project is centralisation of complex orthopaedic procedures to “Specialist Units” and minimum surgeon volumes. We aimed to estimate the effects of implementing minimum unit and surgeon specific volumes upon orthopaedic units within the Severn region.

Practice profiles for surgeons and units were generated using the NJR Surgeon and Hospital Profile Database. Minimum volume thresholds were set at 13 procedures/year for surgeons and 30 procedures/year for units.

Median surgeon volumes were 33 (range 2–180) for primary TKR, 10 (range 2 – 64) for UKR, 2 (range 2 – 41) for PFJR and 5 (range 2–57) for Revision TKR. Amongst 48 surgeons performing UKR, 26 (54%) performed less than 13 procedures per year accounting for 108 (14%) procedures. Amongst 20 surgeons performing PFJR, 19 (95%) performed <13/year, accounting for 56 (58%) of cases. 49 Surgeons performed revision TKR with 24 (49%) performing <13 revisions per annum, accounting 151 (36%) procedures.

Amongst 16 units performing UKR, 8 (50%) performed <30/year, accounting for 16% overall. Revision TKR was performed in 15 units whilst 8 (53%) performed <30/year, accounting for 62 (15%) cases. We invite discussion of the ramifications of minimum surgeon and unit volumes for Orthopaedic services in the Severn Region.

The aim of this study was to document the survivorship and patient reported outcome of the Avon patello-femoral replacement in a consecutive series with follow up of 10 years or more.

All cases performed in Bristol from 1996 onwards were prospectively recorded. Follow up was at 1,2,5,7,10,12 and 15 years with the Bristol Patella Score, the Oxford and WOMAC scores and SF12. Implant survival was analysed using the Kaplan-Meier method.

There were 323 PFJ replacements (280 individuals). Follow up was available for 286 cases in 250 patients (89% follow up). The 10 year survival rate was 77%, falling to 67% at 15 years. The most common reason for revision was tibio-femoral progression (45/74 revisions), with loosening or polyethylene wear recorded in 8 cases. The best results were seen in the youngest and the oldest patients. Good improvements were seen in PROMs, with the mean OKS improving from 19.5 to 34.1 at 2 years and 32.7 at the 15 years.

The Avon patello-femoral knee replacement is a successful long-term treatment for isolated patello-femoral knee osteoarthritis, although further improvements are expected in subsequent series, particularly as indications for surgery have evolved over time.

Total knee arthoplasty (TKA) remains a standard treatment for advanced knee arthritis. The aim of the procedure is to restore function and relieve pain ideally for the rest of patient's life. Patient matched templating (PMT) or patient specific instrumentation (PSI) is a recent development for alignment of TKA components that uses disposable guides. The users of PSI claim it to be the optimum balance of new technology and conventional technique by reducing the complexity of conventional alignment and sizing tools.

To assess the clinical and radiological outcome of Primary TKA done with PSI.

More than 200 cases of TKA have been done in our unit using PSI and we analysed the radiographic outcome of these cases postoperatively. We also reviewed the clinical outcome of 103 patients with 1 year and 43 patients with 2 year follow-up. Data was collected prospectively: pre-operatively and at 1 year and 2 years post-operatively including Oxford knee score (OKS), WOMAC and American knee society score (AKS). Standard AP and lateral films were done pre-operatively and post-operatively.

Mean age was 66 years. There were 56 female and 47 male patients. Mean post-operative angles on standard films were: Alpha = 95.6, Beta = 88.4, Saggittal femur = 3.4 and Saggittal tibia = 90.8. Of the 103 cases with 1 year follow-up, there was significant improvement in all clinical outcome scores. Mean OKS improved from 18 to 39 at 1 year and remained the same at 2 years, WOMAC improved from 40 to 18 in both 1 and 2 years post-op. AKS Total improved from 79 to 173 at 1 year and 170 at 2 years.

Performing TKA using PSI is safe and provides good radiological alignment in the coronal and sagittal plane. Significant improvement in outcome scores were seen at one and two year follow up and reached levels that compared favourably with other reported series of TKA outcome from our unit.

It has been reported that some of the local anaesthetic agents possess antimicrobial activity against clinically-significant bacteria. Although bupivacaine exhibits a bacteriostatic effect at concentrations above 0.25% there are concerns that it might interact with some of the other antibiotics administered to patients. Whilst these interactions may be potentially benign, the risk is that they are antagonistic and that local bupivacaine might predispose the patient to a higher risk of infection.

Bupivacaine is commonly administered as a local anaesthetic following knee arthroplasy; the purpose of this study was to assess its potential interactions with gentamicin eluting from the cement used to fix the device.

A strain of Saphylococcus aureus (29213) with established susceptible Minimal Inhibition Concentration (MIC) and Minimal Bactericidal Concentration (MBC) for gentamicin was used. This organism was inoculated into four types of broth; Mueller-Hinton broth (MH), MH with different concentrations of gentamicin, MH with 0.25% and 0.125% bupivacaine and MH with various combinations of gentamicin and bupivacaine. The broths were incubated at 37C and at 0.5, 1, 2, 3, 6 and 24 hours post inoculation the number of bacteria remaining were counted. From these data kill-curves were generated describing the absolute and individual rates of killing seen with bupivacaine and gentamicin alone and when in combination.

Bupivacaine showed a bacteriostatic effect only at concentrations of 0.25% and higher. All concentrations of gentamicin above or equal to the expected MBC showed bactericidal effect. However, in combination with both strengths of Bupivacaine (0.25 and 0.125%) the bacteriocidal effect of gentamicin was seen at a lower concentration and the rate of killing of bacteria was enhanced.

Bupivacaine has bacteriostatic effect at concentrations above 0.25% in line with published data. In these experiments we have shown that the use of bupivacaine together with gentamicin does not reduce the bactericidal property of the antibiotic and that the bactericidal effect of gentamicin appears to be enhanced by bupivacaine. This would suggest that the local use of bupivacaine is unlikely to increase the risk of infection in patients undergoing knee arthroplasty and may actually be beneficial.

This is a prospective review of consecutive patients who underwent knee revision surgery using the Legion knee system.

Clinical and functional assessments (American Knee Scores-AKS, WOMAC and Oxford knee score-OKS) were carried out preoperatively, one year and 2 years post op. Radiographic evaluation was done at 1 and 2 years included review of standing AP, lateral and skyline views. Figgie's method was used to measure the joint line reproduction.

210 patients underwent revision knee system 103 male: 107 females with a mean age of 66.4 (44–87) yrs. Mean BMI-26.03 (21–50). We had a 2-year follow up for 110 patients. Surgery was carried out at a single centre and performed by Bristol knee specialists.

Indications for surgery were aseptic loosening (84), infection (27) instability (47), pain and stiffness (31), progression of disease (6), peri-prosthetic fractures (15)

The AKS and WOMAC scores at, 1 year and 2 years follow up showed significant improvements in pain and function. The mean total AKS improved from 75.7/200 pre-operatively to 140.5/200 at 2 yrs. Radiographic assessment showed a mean AP coronal femoral angle of 95.3 degrees (89.6–99.9), coronal tibial angle of 90.1 degrees (88–92). The mean sagittal femoral and tibial angles were 88.4 and 90.4 degrees respectively.

The short-term results showed significant improvement in functional and pain scores irrespective of indications for revision surgery. The Legion system has showed good outcome scores that match or beat published series on revisions. It also showed a good ability to restore joint line.

Aim

To analyse the available rotating hinge knee implants available on the market with a view to deriving a rational algorithm for implant selection.

Aim

To assess the outcome and complication rate of rotating hinge knee prostheses in our unit.

Objectives

The aim of this study was to study the short to medium term outcome of a contemporary modular revision knee system used in our centre for managing knee revision arthroplasty.

Aim

To assess the clinical outcome at 1 year of 30 cases of primary TKA performed with PMCB.

Aim

To assess the process of using patient matched cutting blocks in Primary TKA with respect to: radiology, the proposed engineering plans, the process in theatre and cost effectiveness. Background: Patient matched cutting blocks (PMCB) are the subject of much interest in primary TKA. Our unit has experience of over 100 cases with a single system.

Aim

To assess the accuracy of predicted and actual cut alignment from PMCB versus intra-operative computer navigation.

Aim

To assess if there is a reproducible relationship between the width and thickness of the normal patella.

Aim

To assess the survivorship of unicompartmental replacements (UKR) revised to UKR. Background: Partial revision of UKR, or revision to a further UKR is a rarely performed procedure with some data from the Australian registry suggesting that results are not good, with early revision being required.

The gold standard for measuring knee alignment is the lower limb mechanical axis. This is traditionally assessed by weight-bearing full length lower limb X-rays (LLX). CT scanograms (CTS) are however, becoming increasingly popular in view of lower radiation exposure, speed and supine positioning. We assessed the correlation and reproducibility of knee joint coronal alignment using these two imaging modalities.

LLX and CTS images were obtained in 24 knees with degenerate joint disease or failed TKR. Hip to ankle mechanical alignment were measured using the PACS software. Coronal knee alignment was assessed from the centre of the knee, measuring the valgus/varus angle relative to the mechanical axis. Measurements were made by two orthopaedic surgeons (Research Fellow and Consultant) on two separate occasions.

The mean alignment angles measured by observers 1 and 2 on CTS were 180.29° (SD 6.04) and 180.71° (SD 6.13) respectively, while on LLX were 181.04° (SD7.58) and 181.04° (SD 7.72). The measurements between the two observers were highly correlated for both the CTS (r = 0.97, p < 0.001) and the LLX (r = 0.99, p < 0.001). The angles measured on CTS and LLX were highly correlated (r = 0.826, p < 0.001) with high degree of internal consistency (ICC = 0.804). Malalignment of greater than 5° was seen in 19% of the CTS and 35% of the LLX.

There was good correlation between CT scanogram and weight-bearing X-ray measurements in normally-aligned knees. However, as expected, in the malaligned lower limb, the influence of weight-bearing is critical which demonstrates the significance of weight-bearing X-rays.

Patello-femoral arthritis can result in a considerable thinning of the patella. The restoration of an adequate patella thickness is key to the successful outcome of knee arthroplasty.

The objectives were (1) to establish a reproducible patella width:thickness index including chondral surface and (2) to investigate whether there is a difference between bone alone and bone/chondral construct thickness as shown by MRI.

Forty three MRI scans of young adults, mean age 27 (range 17–38), 34 male and 9 female, were studied. Exclusion criteria included degenerative joint disease, patello-femoral pathology or age under 16/over 40 (102 patients). The bony and chondral thickness of the patella and its width were measured. Inter/intra observer variability was calculated and correlation analysis performed.

We found a strong correlation between patella plus cartilage thickness and width (Pearson 0.75, P < 0.001). The mean width:thickness ratio was 1.8 (SD 0.10, 95% CI 1.77–1.83). Without cartilage the ratio was 2.16 (SD 0.15, 95% CI 2.11–2.21), correlation was moderate (Pearson 0.68, P < 0.001). The average patella cartilage thickness was 4.1mm (SD 1.1, 95% CI 3.8–4.5).

The narrow confidence intervals for the ratio of patella width:thickness suggest that patella width can be used as a guide to accurate restoration of patella thickness during total knee or patella-femoral replacement. We would recommend a ratio of 1.8:1.

We present a prospective, randomised, single-centre, multi-surgeon, controlled trial comparing minimally invasive (MIS) and standard approach total knee arthroplasty (TKA).

86 patients undergoing 92 total knee replacements were recruited. 46 operations were randomised to the MIS treatment arm, 46 to the standard control arm. Data collected included postoperative blood loss, length of stay and complications. Patients underwent surgery via a quadriceps sparing or standard medial parapatella approach. All operations were performed using MIS instruments and an identical postoperative care pathway.

The MIS group had a significantly shorter length of stay (1.4 days, p=0.004) and fewer complications (p=0.003). Demographics, operative time blood loss and radiographic alignment were comparable between the groups. There were no deaths, pulmonary emboli or surgical site infections. 1 patient developed DVT and 1 required revision for pain and failure to regain flexion within 9 months of surgery, both in the control group. Nine percent of MIS patients versus 35% controls suffered a complication delaying discharge, of which 2% and 17% related to surgical site problems respectively.

MIS resulted in a shorter admission and fewer complications, whilst achieving satisfactory component alignment. We discuss the potential economic implications.

We present 10–15 year follow-up of 33 patients who underwent Elmslie-Trillat osteotomy for severe patellar subluxation or dislocation. In the literature it has been reported that tibial tubercle osteotomy predisposes to subsequent patella-femoral arthritis, however it has never been documented if pre-existent knee chondral damage has any role in this development. In our group all patients had pre-op knee arthroscopy performed and extant of chondral damage was documented. We preformed an evaluation by long-term follow-up to determine weather pre-op chondral damage was the cause of subsequent osteoarthritis of patella-femoral joint. All patients were invited to attend outpatient clinic for clinical examination and knee radiographs and assessed by an independent research surgeon. Mean age at follow-up was 43 years and average follow-up was 10.5 years (range 10–15 years). 90% follow-up was achieved. Knee function was assessed by clinical scores (Lysholm knee score, American Knee Score, Oxford Knee score, Tegner and Insall knee scores) and three radiographs (AP, Lateral and Merchant views). Four patients had developed significant arthritis and underwent joint arthroplasty. Majority of patients reported good results with no further dislocation. However we noticed that extant of pre-op chondral damage was a significant factor in subsequent development of patella-femoral arthritis. We will present our data which is unique as no previous such long-term results have been reported for tibial tubercle transfers followed-up for more than 10 years and have pre-op arthroscopic documented chondral damage.