Abstract
The technique for removal of bone ingrown extensively coated devices involves cutting the stem below the metaphyseal portion of the stem, followed by removal of the proximal stem and trephine removal of the cylindrical distal portion of the stem. This can be done with or without an extended trochanteric osteotomy (ETO). When the proximal portion of the stem is not bone ingrown (extensive proximal osteolysis, or the stem is broken) or the metaphyseal bone is easily accessed (there is no collar) the stem can be cut through a bone window. In all other cases an ETO at the level where the stem becomes a cylinder is required to disrupt the metaphyseal bone prosthesis interface, cut the stem and extract the proximal portion of the stem.
Glassman described the techniques for removal of cementless stems in 1992. Forty-two loose stems were easily removed, 11 fibrous stable implants were removed with thin osteotomes, and 11 bone ingrown, canal filling, extensively coated stems were removed with trephines. In no cases was reconstruction precluded by stem removal. The critical tools required included manufacturer specific removal tools, high speed burs, thin osteotomes, universal extraction device for connection to the neck, and multiple trephines.
More recently, Kancherla reported the use of trephines to remove 36 porous coated stems. Eighty-six percent of cases were bone ingrown after removal, however complications included an extruded trephine causing a femoral fracture and two periprosthetic fractures thought to be secondary to trephine induced osteonecrosis. The authors recommend bypassing the most distally trephined bone by a minimum of 4cm.
Trephines are very helpful for removing distally fixed stems. Multiple trephines need to be irrigated and changed frequently to avoid dull cutting teeth which can lead to bone necrosis.
