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Updated: Aug 12, 2026
Direct Mouse Trauma/Burn Model of Heterotopic Ossification
Published on: August 6, 2015
Heterotopic Ossification at Tracker Pin Sites Following Robotic-Assisted Total Knee Arthroplasty
Jun Wei Lim1, Chloe Jane Lowe2, Martin Mitchell1
1Department of Orthopaedics and Trauma, Woodend General Hospital, Aberdeen, UK, nhsgrampian.org.
Case:
A 72-year-old Caucasian man presented with left knee osteoarthritis and underwent Mako robotic-assisted total knee arthroplasty (TKA). Two months postoperatively, he complained of mild discomfort in his left quadriceps and limited flexion, with an active range of motion (ROM) from 0° to 60°. At 10 months, his ROM had not improved, and plain radiographs revealed a large, calcified mass in the distal femur, which appeared to be emanating from the tracker pin sites used during Mako robotic-assisted TKA, raising concern for heterotopic ossification (HO). He subsequently underwent excision of the HO and was started on indomethacin.
Conclusion:
Surgeons performing robotic-assisted TKAs should be aware of the potential for HO formation at tracker pin sites as a possible complication, particularly in patients presenting with postoperative stiffness.
