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33rd Annual Scientific Meeting proceedings


Stream:   |   Session: Orthopaedic Short Communications
Date/Time: 06-07-2024 (17:15 - 17:30)   |   Location: Auditorium 1
Effect of cancellous bone compaction on the immediate stability of an angle stable interlocking nail in a distal femoral osteotomy model
Fracka AB1, Dejardin LM1, Chung WC1, Allen MJ2
1Michigan State University, East Lansing, USA, 2University of Cambridge, Cambridge, United Kingdom.

Objectives:

Effective distal femoral varus (DFV) correction via interlocking nailing requires an stable bone-implant interface during condylar nail insertion. Current techniques, which involve reaming a condylar cancellous tunnel, may fail to provide adequate stability prior to locking. Subsequent intraoperative loss of reduction may lead to incomplete varus correction and patellar re-luxation. While compaction has been used to improve screw fixation in cancellous bone, this technique has yet to be evaluated in DFV correction. Our aim was to determine the effect of cancellous bone compaction on the immediate stability of the bone/nail interface using a condylar bone model. We hypothesized that, compared to reaming, cancellous compaction would increase bone/nail interface stability.

Methods:

Short fiber-reinforced epoxy 2-cm OD tubes filled with 12.5-PCF polyurethane foam were used to simulate a mid-size dog femoral condyle. To allow insertion of a 7mm I-Loc nail, 3cm long centrally located tunnels were created via reaming (7mm) or sequential foam compaction using custom mandrels of increasing diameters from 2mm to 7mm (n=4/group). Implanted models were tested in medio-lateral bending under displacement control. Stiffness and maximum load were compared using student t-test (p<0.05).

Results:

Compared to reaming, compaction increased bending stiffness and maximum load by 48% and 100% respectively (p<0.0001).

Conclusions:

Compared to conventional reaming, cancellous compaction significantly increases the immediate stability of the bone/nail interface in a distal femoral osteotomy model. By limiting intraoperative pilot tunnel deformation prior to nail locking, cancellous compaction could reduce intraoperative loss of femoral alignment and thus the risk of postoperative patellar re-luxation.

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