Background
In the present study, we hypothesize that preservation of adequate surface area of the subchondral sclerotic bone on the proximal tibial cut surface would provide a stronger foundation for tibial component support. This would minimize or eliminate the potential for component subsidence or loosening when minor degrees of misalignment are encountered, added to the potential advantage of avoiding complex reconstruction in osteoarthritic varus knees with excessive medial wear. The purpose of this study was to investigate the midterm outcome of total knee arthroplasty upon seating the tibial component partially on the medial sclerotic subchondral bone in varus osteoarthritic knees.
Patients and methods
Proximal tibial resection was kept to a minimum in 54 consecutive primary total knee arthroplasties. The remaining sclerotic surface area on the medial tibial plateau cut surface was freshened with a saw blade, and multiple anchorage holes were made for cement interdigitation. Patients were followed up for a mean period of 38.4 months both clinically and radiologically according to the knee society scoring system.
Results
At the last follow-up, the average clinical knee society score (KSS) was 88.4 (range from 72 to 94) compared with an average preoperative KSS of 32.5. The average knee function score at the last follow-up was 86.3 (range from 68 to 93) compared with the average preoperative functional score of 31.7. The coronal tibial component β angle was within ±3° of neutral alignment in 94% (51) of patients. The mean β angle was 89.6±2.8°, with a mean varus deviation of 0.4° from the neutral angle. At the latest follow-up, there was no was no evidence of component loosening or subsidence in any of the cases in this study.
Conclusion
In conclusion, the proposed surgical approach has proven beneficial to midterm durability and survival of the total knee implant on both clinical and radiographic basis. Avoidance of complex reconstruction is another potential advantage of adopting this technique in osteoarthritic varus knees with excessive medial wear. Further long-term follow-up studies are required to document the long-term durability.