Int Orthop. 2026 Aug 2. doi: 10.1007/s00264-026-06975-0. Online ahead of print.
ABSTRACT
BACKGROUND: Robotic-assisted total knee arthroplasty (TKA) requires pin trackers fixed to the femur and tibia. The influence of femoral pin tracker placement (intra-incisional or extra-incisional) on fracture risk remains controversial, with limited clinical and biomechanical evidence.
METHODS: A retrospective cohort study included 688 patients who underwent robotic-assisted TKA (505 in intra-incisional group, 183 in extra-incisional group). The incidence of femoral periprosthetic fractures was compared between the two groups within three months postoperatively. Finite-element analysis (FEA) simulated femoral biomechanical behaviour under compression, torsion, and bending loads in three models: control, intra-incisional, and extra-incisional groups.
RESULTS: One fracture occurred in the extra-incisional group (1/183, 0.55%), whereas none occurred in the intra-incisional group (0/505), the difference was not statistically significant (Fisher’s exact test, P = 0.266). In the FEA, ultimate loads and fracture patterns were similar among the control, intra-incisional, and extra-incisional models under all three loading conditions, and no simulated fracture initiated at nail channels.
CONCLUSION: Perioperative femoral fracture involving tracker nail channels was rare in this cohort, and its incidence did not differ significantly between intra-incisional and extra-incisional placement. When a standardized pin-placement protocol is followed, either location appears to have a limited effect on short-term fracture risk.
PMID:42542985 | DOI:10.1007/s00264-026-06975-0
