Purpose of the study

To determine the effectiveness, complications and side effects of Rivaroxaban when used for extended thromboprophylaxis in patients undergoing primary and revision knee arthroplasty.

A consecutive group of 150 patients undergoing primary TKA performed by a single surgeon using single prosthesis were studied prospectively. The purpose of this study was to compare the clinical and radiographic results of TKA in obese and non-obese patients.

The patients were categorized into two groups: non-obese (body mass index (BMI < 30 kg/m2) and obese (BMI > 30 to 40 kg/m2). The Primary outcome measures: SF-12 and WOMAC scores were used as generic outcome measures, and the Knee Society scores were used to assess clinical outcome of TKA. The scores were done pre-operatively and at 1, 3 and 5 years post-operatively. Secondary outcome measures included patellar position, anterior knee pain, infections, revision rates, deep-vein thrombosis and pulmonary embolism, length of hospital stay and mortality.

Seventeen patients have died since and none were lost to follow-up. Obese patients had less benefit and overall KSS outcome scores at one year (p-value 0.05) but had similar scores at 3 and 5 years (p-values 0.3 and 0.5). Pre-operative WOMAC and SF-12 scores were significantly worst in obese patients (p-value 0.009 and 0.005) but had the similar outcome at 1, 3 and 5 years. Three patients in the series required revision surgery for infection. One patient had DVT and another had PE post-operatively.

Overall obese patients although had lower KSS scores at one year but had better outcome in SF-12 and WOMAC scores at one year. There was no difference at 3 and 5 years. We found that body weight did not influence adversely the outcome of TKA at medium term.

Introduction: Restoring normal mechanical axis is one of the key goals of the total knee arthroplasty (TKA). The majority of the surgeons resect the tibia perpendicular to its axis in the coronal plane, then use an intra-medullary jig inserted through the centre of the knee or slightly medial to centre of the knee to resect the distal femur at a 6 or 7degree valgus angle. The aim was to establish the safety of using a predetermined valgus angle (VA) and entry point (EP) in the primary TKA. We also studied the relationship between the VA and EP to the height, weight and BMI of the patient.

Materials and Methods: We studied 125 long leg radiographs of 125 patients who underwent TKA under the care of senior author. All the radiographs were taken in the preoperative clinic with knee in full extension and patella facing forward. The radiographs were used to measure the valgus angle and entry point of the femur. The patients with VA between 6–7 degrees and EP at the centre were defined as normal group and rest were defined as outliers.

Results: The VA ranged from 4 to 9.5 degrees (with a mean of 6.8 and SD 1.11). Only 66 (53%) knees had the VA between 6 and 7 degrees. The EP ranged from 30mm medial to 18mm lateral to the centre of the knee with a mean of 7.7mm medial to the centre of the knee (SD 6.1). The EP was at the centre of the knee in 31 (24.8%) knees and lateral to the centre in 19 (15.2%) knees. Only 14 (11.2%) knees were in the normal group. Overall there was no significant relationship between the EP and VA to the height, weight or BMI of the patient at p-value > 0.001.

Conclusions: The resection of distal femur using the predetermined valgus angle, the predetermined entry point is not a safe practice in TKA. The long leg radiographs of the knee should be studied to identify the outliers. In future computer-assisted surgery and digitalisation of the images may obviate the need for this. However, it may be prudent though to use pre-operative templating of long leg radiographs during the learning curve of computer assisted surgery as well.

The aim of this study was to evaluate whether using a predetermined entry point and standard value for valgus cut could restore normal mechanical axis of the TKA.

The study included 125 consecutive patients, who underwent TKA under care of the senior author (NJD). Details of height, weight, BMI were noted. All the radiographs were taken with the patient standing, with the knees in maximum extension, with the patella facing forward. The long leg radiographs were evaluated and the mechanical axis and anatomical axis were marked. The entry point (EP) and the angle between the anatomical and the mechanical axis of the femur ware measured, which is valgus angle of distal femoral cut (VA). Statistical analysis was done using SPSS (Table 1). Proportion of the cases with VA less than 6 degrees or more than 7 degrees were identified. Similarly cases with EP distance less than 0 and more than 5mms were also identified. Cases with VA of 6–7 degrees and EP 0–5mms were identified as one group. Correlation was performed using nonparametric tests.

The results revealed the angle between the anatomical and the mechanical axis ranges from 4 to 9.5 degrees (mean 6.8 degree and standard deviation 1.11 degree). Only 53% had an angle of between 6 and 7 degrees, with 7% of knees having an angle of less than 5 degree or greater than 8 degrees.

The site of entry of the jig showed variation from 30mms medial to the centre to 18mms lateral to the centre with the mean entry point of 5.04mms medial to centre of the notch, with a standard deviation of 8.5mms.

Overall only 33% of the knees templated would have an optimal femoral jig placement and distal femoral angle cut with an entry point in the centre of the notch or up to 5mms medial to centre and a distal valgus cut of between 6 and 7 degrees. The author feel this study gives evidence that if the mechanical axis is to be restored then long leg pre-operative radiographs should be performed and used as a key component to the pre-operative plan.

Table 1. Spearman’s rho correlations, between the valgus angle and entry point to the height, weight and BMI of the patients.

Stem dissociation in modular revision knee replacement due to failure of the frictional lock of the Morse taper has been reported in the literature. However, the medium and long-term implications of stem dissociation are unknown, as clinical outcomes have not been reported. We report a series of 10 cases in which there was intra-operative dissociation of the tibial stem.

Between 1994 and 1999, 98 patients underwent revision total knee replacement for aseptic loosening at our institution. Ten of these patients were noted to have tibial stem dissociation, apparent on the immediate post-operative radiographs. The senior author (RWP) performed all procedures and used a standardized operative technique. The Co-ordinate modular knee revision system was used in all cases. The quality of the bone was noted in all the cases intra-operatively; and was graded as 1) sound bone, 2) soft but intact, 3) soft and fractured cortex.

Our study demonstrates that the tibial stem dissociation did not cause any significant detriment to the clinical outcome on minimum follow-up of six years in nine cases where the tibial metaphyseal cortical rim was intact. In one case, where the medial tibial plateau had a cortical defect, the prosthesis drifted into varus mal-alignment and the patient required a further revision for aseptic loosening. We therefore question whether long canal filling tibial stems are necessary in all revision total knee replacements particularly when the cortical rim is intact and a non-constrained poly-ethylene insert is used.

Introduction: Clinical outcome studies have shown excellent results following unilateral total knee arthroplasty (TKA). A wide Pub Med search failed to find any literature on the outcome of results following bilateral staged TKA.

Aim: To determine the clinical outcomes of patients undergoing bilateral staged TKA.

Material & Methods: Patients who underwent bilateral staged TKA between 1994 – 2002 were assessed using the Knee Society Score (KSS) and Western Ontario and MacMaster Osteoarthritis Index (WOMAC) scoring systems. They were also asked regarding which TKA they considered ‘better’ and why.

Results: We clinically reviewed 110 patients who underwent bilateral staged TKA. The mean clinical follow-up time was 5.13 years. The mean pre-operative KSS was 95.8 for the right knee and 95.5 for the left knee. The mean post-operative KSS was 154.1 for the right knee and 155.9 for the left knee. Patients mean postoperative WOMAC scores for the right knee were; Pain – 1.67, Stiffness – 1.17 and Function – 10.78. Patients mean post-operative WOMAC scores for the left knee were, Pain – 1.77, Stiffness – 1.14 and Function – 10.69. Objectively there was no statistical significance between right and left KSS pre-operatively. There was no statistical significance between right and left KSS and WOMAC scores post-operatively. Subjectively, 44 patients reported their first TKA was ‘better’ than their second. 48 patients reported both TKA’s were as good as each other. 18 patients reported their second TKA was ‘better’ than their first. The 2 main reasons why one TKA was better than the other were pain and range of movement.

Conclusion: Objectively, staged bilateral TKA results in equally good outcome. Subjectively, the first TKA is ‘better’ or equal to the second TKA in 84% of cases. We feel that this information is important during counseling of patients undergoing bilateral staged TKA.

Introduction: Clinical outcome studies have shown excellent results following unilateral total knee arthroplasty (TKA). We are unable to find in the medical literature the outcome of results following bilateral staged TKA.

Aim: To determine the clinical outcomes of patients undergoing bilateral staged TKA.

Material & Methods: Patients who underwent bilateral staged TKA between 1994 – 2002 were clinically assessed using the Knee Society Score (KSS) and Western Ontario and MacMaster Osteoarthritis Index (WOMAC) scoring systems. They were also asked regarding which TKA they considered ‘better’ and why.

Results: We clinically reviewed 110 patients who underwent bilateral staged TKA. The mean clinical follow-up time was 5.13 years. The mean pre-operative KSS was 95.8 for the right knee and 95.5 for the left knee. The mean post-operative KSS was 154.1 for the right knee and 155.9 for the left knee. Patients mean post-operative WOMAC scores for the right knee were; Pain – 1.67, Stiffness – 1.17 and Function – 10.78. Patients mean post-operative WOMAC scores for the left knee were, Pain – 1.77, Stiffness – 1.14 and Function – 10.69. Objectively there was no statistical significance between right and left KSS pre-operatively. There was no statistical significance between right and left KSS and WOMAC scores post-operatively. Subjectively, 44 patients reported their 1st TKA was ‘better’ than their 2nd. 48 patients reported both TKA’s were as good as each other. 18 patients reported their 2nd TKA was ‘better’ than their 1st. The 2 main reasons why one TKA was better than the other were pain and range of movement.

Conclusion: Objectively, staged bilateral TKA results in equal good outcome. Subjectively, the 1st TKA is ‘better’ or equal to the 2nd TKA in 84% of cases. We feel that this information is important during counseling of patients undergoing bilateral staged TKA.

Purpose of study: The purpose of the study was to determine the influence of patient’s pre-operative mental state on post-operative physical outcomes in primary and revision total knee arthroplasty (TKA).

Methods: 100 Primary and 60 Revision TKA patients were prospectively assessed using SF-12 and WOMAC outcome measures. They were assessed pre-operatively and at six and twelve months post-operatively.

All surgery was performed by a single surgeon, using one prosthesis design in each group.

The data were assessed for any correlation between the pre-operative MCS and post-operative PCS, Pain, Stiffness and Function scores using Spearman’s Rank Correlation.

Results: There was a significant positive correlation between pre-operative MCS and post-operative PCS scores at six and twelve months (P=0.01 and P=0.031 respectively) in the primary TKA patients. There was no correlation in the revision patients.

There was a statistically significant negative correlation between pre-operative MCS and six month WOMAC Pain, Stiffness and Function scores (P=0.025, P=0.019 and P=0.011 respectively) in the primary patients. There was no significant correlation with twelve months WOMAC scores.

There was no significant correlation in terms of pre-operative MCS and six months WOMAC scores in the revision patients, but there was a statistically significant negative correlation between pre-operative MCS and the twelve months pain score (P=0.039).

Conclusion: The results support the concept that high generic mental health scores in patients prior to primary TKA are associated with good physical outcomes in terms of both generic health outcome measures and disease-specific outcome measures.

Introduction & Aims: Revision hip arthroplasty surgery is technically demanding and good exposure is a pre-requisite to successful re-implantation. The traditional pertro-chanteric approach gives circumferential exposure of the acetabulum and excellent exposure of the proximal femur. The Trochanteric Slide approach theoretically reduces the incidence of trochanteric pull off and non-union. The aim of this study was to establish the efficacy of the Trochanteric Slide approach to revision hip arthroplasty.

Materials & Methods: Fifty revision hip replacements were performed using the Trochanteric Slide surgical approach. Fixation of the osteotomy was performed with the Dall Miles cable grip system. All patients were prospectively followed for a minimum of 18 months (Mean 3.4 years). 36 of the revisions were for aseptic loosening, 6 for septic loosening, 3 for peri-prosthetic fracture and 5 for recurrent dislocation. In 19 cases, previous revision surgery had been performed.

Results: 8 of the 50 trochanteric re-attachments showed suggestion of movement from the immediate postoperative x-ray. 8 showed less than 5mm migration, 3 showed 5–10mm migration, 1 showed 10–15mm migration and 1 showed 15–20mm migration. Radiological union was definite in 38 cases. Probable union was observed in 5 cases and non-union in 7 cases. 36 hips had a positive Trendelenberg test prior to surgery compared to 11 cases at 12-month review. Trochanteric bursitis was present in 15 cases. Cable end fraying occurred in 8 cases. There were 2 instances of cable breakage and one instance of cable migration onto the prosthesis.

Conclusion: The authors feel that the trochanteric slide approach gives excellent exposure whilst retaining the distal tether of vastus lateralis. This distal tether when combined with cable grip fixation appears to give a good outcome with regards trochanteric migration but is prone to causing trochanteric bursitis.

There has been speculation as to whether the outcome of revision total knee arthroplasty (TKA) is as successful as primary TKA. The purpose of this study was to assess patient outcomes following revision TKA and compare them to patient outcomes following primary TKA.

This study collected data prospectively from patients operated upon by one surgeon using one prosthesis in each group. Patients completed SF12 and WOMAC questionnaires pre-operatively and at six and twelve months post-operatively. In the primary TKA group there were 84 patients. In the revision TKA group there were 60 patients. Statistical analysis was performed using paired and unpaired t-tests.

Results showed that the improvements in SF12 physical scores and WOMAC pain, stiffness and function scores in both primary TKA and revision TKA patients were statistically significant (p < 0.0001). There was no significant difference in the magnitude of the improvement in SF12 physical (p = 0.7145) and WOMAC pain (p = 0.0902), stiffness (p = 0.1557) and function (p = 0.3152) scores between the primary and revision patients following surgery.

The mental scores of patients in both groups showed no significant difference following surgery (Primary p = 0.823, Revision p = 0.7095).

The findings show that primary and revision TKA lead to a comparable improvement in patient perceived outcomes of physical health parameters.

However, there is no significant improvement in patient perception of mental health.

There has been speculation as to whether the outcome of revision total knee arthroplasty (TKA) is as successful as primary TKA, this study was designed to compare the outcomes of primary and revision TKA in order to address this question.

The study collected data prospectively from patients operated upon by one surgeon using one prosthesis design in each group. All patients undergoing revision TKA between 1997 and 2000 were included in the study. 100 consecutive patients undergoing primary TKA between 1997 and 1999 were included in the study. All surgery was performed by the senior author.

Patients completed SF-12 and WOMAC questionnaires pre-operatively and at six and twelve months post-operatively. Mean scores were calculated for the different areas within both outcome measures (WOMAC pain, stiffness and function; SF-12 – physical constant score [PCS] and mental constant score [MCS])

The results were entered into a database and analysed using a combination of two way and simple repeated measures analysis of variance (ANOVA) and t-tests. Only if the result of the ANOVA was significant were post-hoc adjusted t-tests performed on the data values.

WOMAC scores did not differ between the two groups pre-operatively. Both patient groups showed a significant improvement in WOMAC scores at six months (P< 0.0005). In the primary group the pain and function scores improved significantly between six and twelve months (P=0.0258 and P=0.0019 respectively). This was not the case in revision patients.

SF-12 PCS scores were significantly better in the primary patients pre-operatively (P< 0.0005). Both groups showed a significant improvement at six months assessment (P< 0.0005). Neither group demonstrated an improvement between six and twelve months. SF-12 MCS scores did not show any difference between the two groups pre-operatively. No significant change in MCS score occurred during the study in either the primary or revision patients.

The SF-12 and WOMAC health questionnaires are valid, reliable and responsive outcome measures. The study has collected data prospectively from patients operated upon by one surgeon using one prosthesis design in each group. These findings support the concept that revision TKA leads to a comparable improvement in patient perceived outcomes of physical parameters as does primary TKA in both generic health outcome measures and disease specific outcome measures.

Aim: The aim of this study was to evaluate the results of the Co-ordinate revision knee prosthesis (Depuy Ltd, Johnson and Johnson, Warsaw, In) between 1995–2001.

Methods: One hundred and thirty-three knees (126 patients) undergoing revision total knee replacement between 1995–2001 were followed up prospectively. Surgery was performed by one surgeon (senior author). The patients were scored pre-operatively and postoperatively with SF-12 and WOMAC score. Surgery was performed for aseptic loosening (92%) and infection (8%). The changes in SF-12 physical score and the WOMAC score between pre and post operation were significant (SF-12 p < 0.0018, WOMAC pain p< 0.0001, WOMAC stiffness p< 0.0001, WOMAC Function p< 0.0001)). The prosthesis produced reliable relief of pain and improved range of movement with minimal complications.

Conclusion: This modular knee revision system produced satisfactory results in dealing with bone loss and instability in the medium term.

We report the role of our advanced nurse practitioner (ANP) with particular relevance to cost effectiveness, patient satisfaction and data collection.

Our nurse practitioner has been involved in arthroplasty care since 1996. Her duties include preoperative assessment, health advice, informed consent, clinical follow up and maintenance of a database for research/audit. Follow up radiographs are reviewed regularly by the entire medical team in a teaching environment. Relative costs of this service were calculated using outpatient charging data. 100 postal questionnaires were used to assess patient satisfaction. Patients answered 13 questions relating to the service they received.

Knee arthroplasty follow up through the nurse led clinic was half the cost of follow up through the consultant led clinic. 80 patients returned the postal questionnaire. Responses were very supportive of the nurse practitioner service. 76 (95%) of patients were happy to be assessed by the ANP and felt that their problems were dealt with appropriately. 17 (21%) of patients felt they should be seen by a surgeon at some stage during their routine follow up. Overall, 75 (94%) of patients were very satisfied or satisfied with the service, 1 (1%) was dissatisfied and 4 (5%) did not answer this question.

Increasing patient numbers and demand for high quality care combined with a decrease in doctors hours worked has lead to a shortage of time for discussion of ‘prehabilitation’ and postoperative care. Long term clinical and radiological follow up leading to adequate research and audit must not be compromised. A trained nurse practitioner working in conjunction with the surgical team is a cost effective way of improving total patient care, audit and research within a department. We have found a high degree of patient satisfaction with this approach.