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).