Knee arthrodesis using biplanar external fixation and vascularised patella autograft: a novel approach

Abstract

Background: Knee arthrodesis, though a rare procedure in current practice, remains an option in managing non-reconstructable, non-functional knees, especially if from persistent periprosthetic joint infection (PJI). It is even more of an option because of the continuous rise in the need for total knee arthroplasty with the inevitable increase in complications, including periprosthetic joint infection. The union rate of knee arthrodesis is largely determined by both mechanical and biological stability across the bone contact surfaces. This study aimed to determine the pattern of bone union in knee arthrodesis when a pedicled vascularised patella autograft was integrated into the knee fusion and stabilised with biplanar external fixators. The secondary aim was to determine the functional outcome using this procedure.

Methods: A retrospective descriptive study of knee arthrodesis was done at a single-centre tertiary hospital using vascularised patella autografts and biplanar external fixators. The study period reviewed was from January 2014 to December 2023, and it included adults 18 years and above.

Results: A total of eight knee arthrodesis surgeries were included in this study. The mean age at arthrodesis was 58.5 years (SD 12.2; range 42–74). Six (75%) patients were male. Indications for arthrodesis were persistent periprosthetic joint infection (38%), tuberculosis of the knee (25%), and chronic osteomyelitis (25%). Complications occurred in one individual. At six weeks postoperative follow-up, the fusion rate at the patellofemoral and the patellotibial bone surfaces was 63% (n = 5), and no fusion was observed at the tibiofemoral surfaces of all eight patients. At 12 weeks postoperative follow-up, complete fusion across all bony surfaces was noted for all eight patients. The mean external fixation duration was 12.5 weeks (range 11–13). The mean postoperative lower extremity functional scale score increased from 32 (range 21–42) at six weeks to 46 (range 38–53) at 12 months. There was complete eradication of infection postarthrodesis in all cases.

Conclusion: Fusion rate across the patellofemoral and patellotibial bone surfaces preceded that across the tibiofemoral surface. This finding suggests that this novel technique can enhance the fusion rate of knee arthrodesis by optimising the biology around the knee in a mechanically stable environment.

Level of evidence: 3