The long-term clinical and radiological results of 63 uncemented Low Contact Stress (LCS) total knee replacements in 47 patients with rheumatoid arthritis were reviewed. The average age at the time of surgery was 69 years (53–81). At a mean follow up of 22 years (20–25), 12 patients (17 knees) were alive, 27 (36 knees) had died, and 8 patients (10 knees) were lost to follow-up. Revision was necessary in seven patients (7 knees) (11.1%) at mean 12.1 years following surgery. Four revisions were performed due to meniscal bearing wear, two for collapse of the tibial component, and one for aseptic loosening. Evidence of post-operative infection occurred in two knees (3.2%) within 6 weeks of surgery but resolved with antibiotics. Within the group of deceased patients, five had undergone revision (included in total revisions) but otherwise the primary implant remained For all living patients, the mean Oxford Knee Score (/48) was 30.2 (16–41) at latest follow up at mean 19.5 years (15–24.7) following surgery. Mean active flexion was 105 degrees (90–150) at this time point. Our recorded survival rate of the uncemented LCS total knee replacements in patients with rheumatoid arthritis was therefore 88.9% at mean 22 years, or worst-case survival of 73.0% if patients lost to follow-up were considered failures. From a review of the literature and as far as we are aware, this study represents the longest follow up of any uncemented knee arthroplasty performed in a cohort of patients with rheumatoid arthritis.
Anterior knee pain following primary total knee replacement (TKR) is a common problem with average reported rates in the literature of approximately 10%. Symptoms are frequently attributed to the patellofemoral joint, and the treatment of the patella during total knee replacement is controversial. There is no article in the literature that the authors know of that has specifically evaluated the effect of patella rim cautery on TKR outcome. This is a denervation technique that has historically been employed, with no evidence base. A prospective comparative cohort study was performed to compare the outcome scores of patients who underwent circumferential patella rim cautery, with those who did not. Patients who had undergone a primary TKR were identified from the unit's arthroplasty database. Two cohorts, who were age and gender matched, were established. None of the patients had their patella resurfaced, but all had a patellaplasty. The Low Contact Stress TKR (Depuy International) was used in all cases. The effect of circumferential patella rim cautery on the Oxford Knee Score (OKS) and the more anterior knee pain specific Patellar Score (PS) a minimum of 2 years post surgery was evaluated. Previous reports have suggested that a change of 5 points in the OKS represents a clinical difference. A sample size calculation based on an effect size of 5 points with 80% power and a p-value of 0.05 would require a minimum of 76 patients in each group. There were 94 patients who had undergone patellaplasty only, and 98 patients who had supplementary circumferential patella rim cautery during their primary TKR. The mean OKS were 34.61 and 33.29 respectively (p=0.41), while the PS scores were 21.03 and 20.87 (p=0.87). No statistically significant differences were noted between the groups for either outcome score. Patella rim cauterisation is unnecessary in primary TKR.
