Abstract

Introduction

The MHRA guidelines for metal on metal (MOM) suggest cobalt and chromium levels of more than 7ppb as potential for soft tissue reaction. However, in some patients soft tissue reaction is seen even in the presence of normal serum metal ions levels.

Background

Revision surgery for a failed metal on metal (MoM) hip arthroplasty is often unpredictable and challenging due to associated massive soft tissue and bony lesions. We present the analysis and early outcomes of revision surgery in failed MoM hip arthroplasties at our institution.

One of the routinely used intraoperative tests for diagnosis of periprosthetic infection (PPI) is Gram stain that is reported to carry a very high specificity and a poor sensitivity. However, it is not known if the result of this test can vary according to the type of joint affected or the number of specimen samples collected. This study intended to examine the role of this diagnostic test in a large cohort of patients from single institution.

A review of our joint registry database revealed that 453 total knee arthroplasty (TKA) and 551 total hip arthroplasty (THA) of which 171 and 150 cases were respectively infected underwent revision surgery during 2000–2005 and had intraoperative cultures available for interpretation. A positive gram stain was defined as the visualisation of bacterial cells or ‘many leukocytes’ (> 5 per high power field) under the smear. The sensitivity, specificity, and predictive values of each individual diagnostic arm of Gram stain were determined. Combinations were performed in series that require both tests to be positive to confirm infection and in parallel that necessitate both tests to be negative to rule out infection. This analysis was performed for THA and TKA separately and later compared for each joint type.

The presence of organism cells and ‘many’ neutrophils on a Gram smear had high specificity (98%–100%) and positive predictive value (89%–100%) in both THA and TKA. The sensitivities (30%–50%) and negative predictive values (70%–79%) of the two tests were low as expected among both joint types. When the two tests were combined in series the specificity and positive predictive value were absolute (100%). The sensitivity (43%–64%) and the negative predictive value (82%) improved among both THA and TKA.

The presence of organisms or ‘many’ leukocytes on the Gram smear can confirm PPI in TJA. As expected, the sensitivity and negative predictive value of the two tests were low, and therefore infection could not be safely ruled out. Although the two diagnostic arms of Gram stain can be combined to achieve improved negative predictive value (82%), Gram stain continues to have poor value in ruling out PPI. With the advances in the field of molecular biology, novel diagnostic modalities need to be designed that can replace these traditional and poor tests.

Aim: To analyze results of flat on flat geometry with posterior retaining arthroplasty. Materials: 469 knees were performed in patients between 1988 and 1990 done by one surgeon and followed prospectively. Survivorship analysis and log rank test were done. Assessment was done with Knee Society evaluation system. Results: The average age at surgery was 70 years. No patient was lost to follow-up. 294 were done in males and 175 in females. Osteoarthrosis was diagnosis in 445 knees (94.2%) and rheumatoid arthritis in 24 knees (5.8%). The average follow up was 10.2 years. All living patients had a minimum of 10 years of follow up. There was significant improvement in the knee score, function score and range of motion following surgery. Failure occurred in eight knees (1.7%). The survivorship analysis showed cumulative survivor of implant was 99.4% at 14 years (CI- 97.1% to 99.8%). Gender, age at surgery, and diagnosis were not significant factor in outcome. Conclusions: The geometry of flat on flat design continues to work satisfactory despite the retention of posterior cruciate at follow-up of 10 years. Results compares well reported results of more conforming designs knee arthroplasty during the same period.

Aims: To asses the outcome of the knee arthroplasty in patients under 55 years old. Methods: 59 knees were performed in patients who were 55 years old and above between 1976 and 1990. No patient was lost to follow-up. The assessment was done using the Knee Society scoring systems. Survivorship analysis was done using the Kaplan-Meier method and analysed with log rank test. Results: The average age at surgery was 48 (19–55) years. There were 25 male and 34 female. Osteoarthrosis was diagnosis in 38 knees and 21 had rheumatoid arthritis. All living patients had a minimum of 10 years (10–23) of follow up. Failure occurred in five (8.4%). 82% of patients had complete pain relief and 91% the knee had excellent knee score (of more than 85) at the final follow up. Survivorship analysis showed implant survival of 90% at 15 years, and 75% at 23 years for revision as end point. Diagnosis had no significant effect on the survivorship (p=0.66). Conclusions: The conventional total knee arthroplasty provides in this young group of patients with excellent clinical results and moderate survivorship analysis for 23 years follow-up.

Aim: is to present 24 years survivorship analysis of 1033 posterior cruciate retaining knee arthroplasties and to identify inherent risk factors, which can lead to higher rates of failure. Materials: 1033 primary total knee arthroplasties with posterior cruciate retention done under the supervision of one surgeon and were followed in a prospective fashion. Results: No patient was lost to follow-up. The minimum follow-up in living patients was of 10 years. Average age at surgery was 69.5 years. 89 knees (9%) had rheumatoid arthritis. Revision was done in 26 (2.5%) for failure and in 5(0.48%) knees for infection. The probability of survival of implant for revision was 95% at 15 years, 89 at 20 years and 83% at 24 years. The survivorship for OA was 82% and 94% was for RA (log rank, p=0.07). Survival for males was 89% and 81% for females (p= 0.53). The regression analysis showed length of follow-up (0.03) was signiþcant and prosthesis design (p=0.001) while age at surgery (p=0.75) and diagnosis (p=0.64) were not. Conclusion: The long term survival was 83% at 24 years of primary total knee arthroplasty. The signiþcant of length of follow-up and prosthetic designs reßects the use of the implant, and of indirectly suggestive of polyethylene wear.

Aim of this study is to evaluate the long-term results of the posterior cruciate retaining knee arthroplasty in osteoarthritis patients. Material and Methods: 943 consecutive total knee replacements in patients with osteoarthritis were performed. All knees had cemented components with retention of the posterior cruciate ligament followed in prospective fashion. Assessment was done by Knee Society clinical and radiographic evaluation systems. Survivorship analysis was done using the Kaplan-Meier method. Results: The average follow-up was 10.8 years. All living patients had a minimum of 10 years (10–24) follow up. The average age at surgery was 71 years. Revision was carried out in 20 knees in OA (2.1%). 87% were pain free and 91% were rated excellent as per the Knee Score. The survivorship analysis showed the implant survival at 15 years 96%, 20 years was 88% and 24 years was 82 (63 to 92%). The age at surgery, gender and design of prosthesis were not significant for survivorship analysis. Conclusions: Total knee arthroplasty provides an excellent survivorship analysis and clinical results at 24 years and seems to have better results than published hip studies.

Aim: The purpose of this study is to evaluate the longest results of Total Condylar knee arthroplasty. Material: Between 1976 and 1982, 159 consecutive primary total knee replacements were performed. All knees were followed in prospective fashion. Assessment was done by Knee Society methods. Survivorship analysis was done using the Kaplan-Meier method and analysed with log rank test. Results: No patient was lost to follow-up. One hundred three knees lost to natural cause (death), while 56 knees were available at þnal follow-up with their average of 20 years (19 to 24 years). The average age of follow-up was 65 years. 57 knees were done in male and 102 knees were in female. Revision surgery was carried out in 7 knees (4.4%). 90% of living patients were pain free. 90% had excellent knee score while only 10% had excellent function. 24 years survivorship was 89% (77 to 95%) for endpoint of revision surgery. Conclusions: Total Condylar knee arthroplasty provides excellent pain relief and knee score with only moderate improvement in the functional status. Total Condylar knee arthroplasty continues to be gold standard in total knee arthroplasty. This is longest reported results of Total Condylar knee arthroplasty.

Aim of this study is to evaluate the long-term results of the posterior cruciate retaining knee arthroplasty in rheumatoid arthritis. Materials: 89 consecutive total knee replacements in patients with Rheumatoid arthritis (RA) were performed. All knees had cemented components with retention of the posterior cruciate ligament followed in prospective fashion. Assessment was done by Knee Society clinical and radiographic evaluation systems. Survivorship analysis was done using the Kaplan-Meier method. Results: The average follow-up was 9.8 years. All living patients had a minimum of 10 years (10–20) follow up. The average age at surgery was 61 years. Revision was carried out in 4 knees in RA (4.4%). 89% were pain free and 93% were rated excellent as per the Knee Score. 90% of the knees were stable. The survivorship analysis showed the implant survival at 20 years was 94% (85 to 97%). Conclusions: With 94% survival rate and 93% excellent results in this long-term study conþrms the safe use of a posterior cruciate retaining knee arthroplasty in a patients with rheumatoid arthritis.