Evaluation of the Early-Mid-Term Results of Isolated Tibial Insert Exchange After Total Knee Arthroplasty.

Objective: This study aimed to assess the early and mid-term results of patients who had undergone total knee arthroplasty (TKA) and then underwent an isolated tibial insert exchange due to tibial insert fracture and/or melting.

Methods: A retrospective study was conducted at the Orthopedics and Traumatology Clinic in a secondary-care public hospital in Türkiye on seven knees of six patients aged 65 years and above who underwent an isolated tibial insert exchange and were followed up for at least six months. Pain and functional assessments of the patients were made with the visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) performed at the last control before the treatment and at the final follow-up visit after the treatment.

Results: The median age of the patients was 70.5 years. The median length of time between the primary TKA and the isolated tibial insert exchange was 5.96 years. After isolated tibial insert exchange, the patients were followed for a median of 268 days and a mean of 414 days. The WOMAC pain, stiffness, function, and total indexes were median 15, 2, 52, and 68, respectively, before the treatment. In contrast, the final follow-up WOMAC pain, stiffness, function, and total indexes were median 3 (p = 0.01), 1 (p = 0.023), 12 (p = 0.018), and 15 (p = 0.018), respectively. It was observed that the median VAS, which was "9" preoperatively, showed a statistically significant improvement to become "2" in the postoperative period. A strong negative correlation was found between age and the amount of decline in the total score of the WOMAC pain scale (r = -0.780; p = 0.039). There was a powerful negative correlation between the body mass index (BMI) and the amount of decline in WOMAC pain scores (r = -0.889; p = 0.007). A strong negative correlation was found between the length of time passing between two surgical procedures and the amount of decline in the WOMAC pain score (r = -0.796; p = 0.032).

Conclusion:  Individual patient factors and prosthetic conditions should be considered undoubtedly when determining the best revision strategy in TKA patients. In cases where the components are well-aligned and well-fixed, isolated tibial insert exchange is an alternative to revision TKA since it is less invasive and more cost-effective.