Cemented Total-Knee Arthroplasty in Rheumatoid Arthritis Patients Aged Under 60 Years
Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by synovial hyperplasia and joint destruction. Among the joints affected by RA, the knee is the most commonly involved, with approximately 25% of patients requiring joint replacement within 22 years of diagnosis. Total-knee arthroplasty (TKA) has emerged as a successful treatment for patients suffering from severe joint pain due to osteoarthritis or RA. However, concerns regarding increased loosening rates and the potential need for multiple revision surgeries have traditionally discouraged the use of TKA in patients under 60 years old. Despite these concerns, recent studies have shown encouraging results in younger patients, though mid-term follow-up data remain limited. Additionally, the topic of patellar resurfacing in TKA remains controversial, with some studies finding no significant differences between resurfaced and non-resurfaced arthroplasties, while others advocate for routine patellar resurfacing.
This study aimed to evaluate the mid-term survival of a successful knee arthroplasty design in RA patients under 60 years old and to compare the outcomes between resurfacing and non-resurfacing groups. The inclusion criteria for patients in the study were: (1) age under 60 years, (2) diagnosis of RA, (3) use of a cemented condylar prosthesis, and (4) a follow-up period of at least two years. A total of 47 RA patients (68 knees) who met these criteria were evaluated post-operatively. These patients underwent cemented TKA at the Orthopaedics Department of Peking Union Medical College Hospital between January 2003 and January 2008. Two patients were lost to follow-up.
All patients received cemented condylar prostheses, with 16 knees receiving cruciate-retaining prostheses, 52 knees receiving posterior-stabilized prostheses, and 27 knees undergoing patellar resurfacing during the initial surgery. The post-operative management protocol was consistent across all patients and included the administration of low molecular weight heparin, three doses of a second-generation cephalosporin, bedside continuous passive motion machine therapy, physical therapy with partial weight-bearing, and quadriceps and hamstring strengthening exercises starting on the second post-operative day.
Radiographic evaluations were conducted according to the Knee Society radiographic evaluation system. Anteroposterior and lateral radiographs were analyzed for the presence and progression of radiolucency lines at the bone-cement and prosthesis-cement interfaces, following the Knee Society guidelines. Clinical outcomes were assessed using the passive range of motion, the Hospital for Special Surgery (HSS) score, and the visual analog scale (VAS) for anterior knee joint pain during stair climbing, both pre-operatively and at the last follow-up. The greatest value of the motion arc was measured in the supine position without weight-bearing to compare the range of motion.
Patients with at least one abnormally high value in these indexes received surgical therapy. The median disease activity level, as measured by the Disease Activity Score 28, was 5.8 (range: 3.9–6.9), indicating moderately or extremely active RA. Stratification analysis was performed based on patellar resurfacing, and no significant differences were found between the resurfacing and non-resurfacing groups in terms of the assessed outcomes.
The median HSS score improved significantly from 43.4 (range: 10–79) pre-operatively to 95.5 (range: 49–124) at the last follow-up (P < 0.01). Similarly, the median VAS score decreased from 7.59 (range: 6–8) pre-operatively to 0.25 (range: 0–2) (P < 0.001). The overall arc of flexion improved from a median of 101.62° (range: 25°–150°) pre-operatively to 110.96° (range: 70°–150°), while the extension of the knee decreased from a median of 14.78° (range: 0°–54°) pre-operatively to 2.53° (range: 0°–10°). Stratification analysis based on patellar resurfacing revealed no significant differences in HSS score, VAS score, or range of motion between the two groups. However, both subgroups showed significant improvements in post-operative HSS scores compared to their pre-operative scores (P < 0.05).
The radiographic follow-up period lasted an average of 8.3 years (range: 2–33 years), with radiolucency at the bone-cement and prosthesis-cement interfaces of each component examined. The median femorotibial angle was 0.03° varus (range: -10° to 15°) pre-operatively and 1.65° varus (range: -11° to 30°) at the last follow-up. On anteroposterior views, the average femoral component flexion angle and tibial component angle were 97.9° (range: 94°–115°) and 89.1° (range: 82°–92°), respectively. On lateral views, the average femoral component flexion angle and tibial component angle were 2.2° (range: -10° to 15°) and 87.0° (range: 80°–95°), respectively.
Two complications were reported during the follow-up period. One knee (1.5%) developed a post-operative infection in the 13th month after surgery, requiring implant removal and the filling of antibiotic-impregnated cement. Revision surgery was performed six months later. Another knee (1.5%) experienced transient peroneal nerve palsy, which resolved after conservative therapy. No wound-related complications were reported.
In conclusion, TKA achieved favorable clinical and radiological outcomes in RA patients under 60 years old. The study found no significant relationship between patellar resurfacing and improvements in HSS scores, suggesting that patellar resurfacing and denervation may have similar effects on improving knee function. There were no significant differences in HSS scores, VAS scores, or range of motion between the resurfacing and non-resurfacing groups. The findings suggest that TKA should not be delayed in younger RA patients when the surgery is deemed necessary.
doi.org/10.1097/CM9.0000000000000502
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