Impaction bone grafting for the reconstruction of large bone defects in revision knee arthroplasty.

Objective: Regeneration of autologous bone stock and formation of a stable implant bed by impaction of morselized bone allograft.

Indications: Bone loss after septic and aseptic loosening or tumour resection.

Contraindications: Persistent infection, one-stage septic revision, poor therapeutic compliance, extensive uncontained metaphyseal defects with cortical thinning of the diaphysis.

Surgical Technique: Whilst the surgeon removes the loose prosthesis, the assistant prepares the graft. The medullary canal is sealed with a cement restrictor. Graft particles of different sizes are densely impacted around a trial stem. The highest level of stability is achieved by using large particles interspersed with small filler particles. Low-viscosity cement facilitates cement penetration and ensures strong interdigitation with the impacted graft mass after implantation of the prosthesis. Uncontained metaphyseal defects are treated with prosthetic augments.

Postoperative Management: Gait training, physiotherapy with isometric quadriceps exercises, partial weight-bearing for 6 weeks, resistance training begins 8 weeks postoperatively.

Results: Between 2010 and 2012, 28 patients with large bone defects [Anderson Orthopaedic Research Institute (AORI) grade: 21 × F3, 3 × F2, 13 × T3, 8 × T2] underwent total knee revision with impaction bone grafting. The mean follow-up was 27.7 months (range 21-47 months). On average, patients had undergone 2.5 previous revisions. Implant survival was 82.0 % (95 % CI = 62.5 %-92.1 %) for any reason of revision as the endpoint and 93.1 % (95 % CI = 74.5-98.4 %) for aseptic revision as the endpoint. The mean postoperative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score was 35.4 (range 3.3-101.6, SD ± 26.2). The mean KSS was 70.6 (range 20-100, SD ± 26.8).