Megaprostheses in the treatment of periprosthetic fractures of the knee joint: indication, technique, results and review of literature.

BACKGROUND: Periprosthetic fractures (PPFs) after total knee arthroplasty (TKA), especially in patients with multiple revisions, remain challenging mainly due to bone quality and loss of bone stock. Megaprostheses, although providing immediate stability and weight bearing, are rarely used in this indication. The aim of the study was to provide a description of the surgical technique and evaluate the outcome of this technique with respectable published data.

MATERIALS AND METHODS: Systematic literature review revealed seven studies dealing with treating PPF after TKA using megaprostheses. Including the results of 11 cases treated in our institution between January 2008 and December 2014, 144 megaprostheses have been evaluated in the current literature with indication of PPF after TKA. Mean age at operation ranged from 68.4 to 81 years and mean follow-up from 6 to 58.6 months.

RESULTS: Revision rates after implantation of megaprostheses in PPFs ranged from 0 % (two studies with a mean follow-up of 6 and 33 months, respectively) to 55 %, all primarily performed for mechanical and nonmechanical failures (20 and 25, respectively). However infection was the most predominant reason for nonmechanical failure. Mortality rates ranged from 6.6 % after 1 year to 45 % after a mean follow-up of 34 months.

CONCLUSION: Megaprostheses represent a valuable option in distal femoral PPFs type 3 according to Su et al., as well as proximal tibia PPFs type 1B according to Felix et al., with loose tibial components. Infection remains the most frequent nonmechanical complication. Prospective clinical studies are required to exactly define the outcome of this technique in PPFs; use of the Henderson classification system would allow comparison between megaprostheses in oncological and nononcological indications.