Table 4.

Pearls and Pitfalls

Pearls

Most HO is located at the indirect and direct heads of the rectus femoris, so very often central compartment work can be accomplished around the existing HO.

Depending on the location of HO, the anterolateral and anteromedial portals may have to be modified slightly, but using the spinal needle to confirm trajectory before making skin incisions can be helpful.

Using the RF ablation device, facing the HO fragment, can allow for careful removal of the bone alone, with maintenance of the surrounding soft tissues.

Be prepared to remove the HO with a Kocher or locking grasper so that the fragment is not lost in soft tissues as the fragment is being removed. Portals may need to be enlarged, or additional percutaneous portals created for placement of grasping instruments.

Postoperative treatment with Indomethacin (75 mg extended release daily for 4 days) (with optional Naprosyn 500 mg twice daily from postoperative days 5-30) is recommended by the authors to prevent recurrence of HO.

Pitfalls

HO can be very vascular, so if using a burr to remove a fragment of bone, be prepared to use the RF device to obtain hemostasis.

HO must be mature before removal, because removing HO when it has not yet matured can lead to recurrence. The maturation process typically takes 8-10 weeks from the inciting injury.17

If HO prevents entry into the central compartment, an outside-in approach can be used, where the peripheral compartment is accessed first, HO is arthroscopically removed, and then the central compartment is accessed.

HO, heterotopic ossification; RF, radiofrequency.