Use of an new modular revision arthroplasty system for the knee reconstruction

Abstract

Objective: Reconstruction of stable knee joint kinematics using modular axis-guided revision implants after failed knee arthroplasty surgery. Indications: Revision implant for bone defects (type Anderson Orthopaedic Research Institute [AORI] III) in case of revision arthroplasty. Primary implant in case of mediolateral instability (>grade I) or multidirectional instability. Contraindications: Persistent or current joint infection, general infection (e.g. pneumonia), missing metaphysis femoral and/or tibial, insufficient extensor apparatus. Surgical technique: Standard approach extending the previously used skin incision. Arthrotomy, synovectomy and collection of multiple samples for microbiological and histopathological analyses. Preparation of the femur with reamers of increasing diameter. Subsequently, a reference stem is anchored and after referencing the correct rotation and joint line height; the femoral osteotomy is performed after fixation of the 5‑in‑1 cutting block. Following the femoral osteotomy, the box of the femoral prosthesis is prepared. In addition, the tibia is prepared using an intramedullary reference system. Level of constraint and additional tibial augmentation is chosen according to the amount of defect bone and according to ligament stability. Postoperative management: Full load bearing; standard wound control and sterile dressings; limitation of active/passive range of motion only in case of weakened extensor apparatus. Results: Between 03/2011 and 05/2018, a total of 48 patients underwent revision arthroplasty using the described system. The mean follow-up was 24 months (range 21–35 months). In 30 of the 48 cases, a rotating hinge variant was implanted, while in 18 cases a semiconstrained variant was implanted. Indications to revision arthroplasty: infection (n = 22), aseptic loosening (n = 11), instability (n = 11), periprosthetic fracture (n = 3) and PMMA allergy (n = 1). In 11 cases, revision had to be performed due to persistent infection (n = 6) and aseptic loosening (n = 5): 9 cases could be successful treated by a two-step revision procedure, while in 2 cases it was necessary to perform an arthrodesis. The 2‑year implant survival rate was 77%.