Objective: Primary and long-term fixation of cementless metaphyseal implants in knee revision arthroplasty cases with large bone defects.
Indications: All tibial and femoral bone defects AORI grade 2 and 3.
Contraindications: Cases where stable uncemented fixation of the metaphyseal implant is not possible.
Surgical technique: Pre-operative evaluation of the failure mode and implant fixation planning. After opening the joint, a synovectomy and mobilisation of medial and lateral recesses routinely performed. Testing of ligamentous stability and implant fixation undertaken before explantation. Removal of the bearing, femoral and tibial components with osteotomes or oscillating saw. Tibial diaphysis prepared with reamers, and metaphyseal preparation with broaches and stem extension. Placement of the metaphyseal broach for height with respect to the tibial joint line and rotational stability assessed. Tibial tray size and position determined before implanting the sleeve, stem and tray trial. The tibial trial provides a stable platform for analysis of the extension and flexion gaps with spacer blocks. Diaphyseal reamers used to identify the anterior femoral bow. Metaphyseal broaches used to achieve stable fixation up to the resection line marked on the handle. Distal femoral freshening cut in 5° or 7° of valgus made to accommodate distal augments as needed. Positioning of the 4-in-1 block with reconstruction of the posterior off-set and cutting for posterior augmentation. Selection of a box cut corresponding to the amount of constraint needed. Trial insert with appropriate, stem, sleeve, condylar femur and augments introduced. Bearing size, joint stability and ROM assessed. Patella alignment and the need for patella replacement or revision determined. The definitive implants are cemented at the joint surface, with metaphyseal sleeves and diaphyseal stems are uncemented.
Postoperative management: Full weight bearing as tolerated, physiotherapy, lymph drainage and pain therapy are routine with no specific post-operative management required.
Results: Between 2007 and 2011, 193 sleeves (119 tibial/74 femoral) were implanted in 121 aspetic knee revision arthroplasties. After average of 3.6 years they were analysed clinically and radiographically. The AKSS (American Knee Society Score) increased from 88 ± 18 to 147 ± 23 points (p < 0.01). ROM (range of motion) increased from 89 ± 6° to 114 ± 4°. Overall revision rate was 11.6 %. Only 4 sleeves revised for aseptic loosening (2 % of total sleeves). An additional 10 revisions performed mainly for infection (3.3 %) or ligament instability (3.3 %).