3D preoperative plan assisted total knee arthroplasty after knee arthrodesis with patella absence: a case report.

Purpose: The conversion of knee arthrodesis to total knee arthroplasty (TKA) is a challenging procedure. This article aims to report a case of fusion knee with patellar absence who was converted to TKA and has achieved good results.

Methods: The patient, a 23 years old Tibetan Buddhist monk, sustained a left knee joint injury at the age of 12 due to a car accident, leading to subsequent knee arthrodesis at 18 years old as a result of recurrent severe infections. However, this procedure hindered his ability to perform daily meditation practices that required bending both knees and sitting cross-legged. After adequate preoperative preparation, with the help of customized osteotomy guide plate and customized 3D-printed porous tantalum patella, the 3D preoperative plan assisted TKA after arthrodesis was performed. The knee function was followed up to explore the clinical effect of above-mentioned surgical procedure.

Results: A 1-year follow-up showed significant improvement in postoperative knee function with improved scores for function outcomes, and the patient was satisfied with the conversion. The patient's left knee improved significantly from preoperative immobility with 5° of fixed fusion to postoperative ROM of 0° to 100°, and the patient could squat and stand up, walk on the flat ground, and go up and down stairs.

Conclusion: Adequate preoperative communication with patients and good expectation management are crucial for ensuring favorable prognoses. Perfect preoperative planning and its reliable implementation during operation are essential. Additionally, postoperative rehabilitation and proactive management of complications play pivotal roles in achieving optimal clinical outcomes.

Level of evidence: IV.