Telescope allograft method to reconstitute the diaphysis in limb salvage surgery

Abstract

We propose a surgical technique for structural allograft reconstitution of the diaphysis of long bones, maximizing surface contact between host and allograft bone. This method, analogous to a telescope, overlaps the graft and host bone, theoretically increasing bone surface contact substantially. We report the outcome of 22 telescoped allograft junction sites in 19 patients who lacked sufficient host bone to accommodate a regular-length stemmed implant. This joint-sparing reconstruction preserved 15 of 16 adjacent joints at risk for replacement. Five patients needed additional surgery, but none for nonunion. The diaphyseal length could be reconstructed enough so that a short prosthesis (less than the critical 40% of total bone length) could be used. This biologic method to reconstruct major segments of the diaphysis is best suited for patients with quantitatively or qualitatively deficient residual bone stock after tumor resection or prosthetic revision. We believe it is an excellent technique for revision knee megaprostheses when there is a short remnant of proximal femur.

Level of evidence: Level IV, therapeutic study.

Fig. 1

This figure depicts the difference in surface area between the telescope and the traditional end-to-end techniques. For simplicity of the illustration, the ellipsoidal cross section is assumed to have equal lengths of the x and y axis (ie, a circle.).

Fig. 2

The telescope technique is shown. The allograft is inverted and condyles cut off. The medullary canal is contoured to accept the graft. The graft is impacted onto the host, creating 5 cm of overlap. A long-stemmed prosthesis is cemented into position.

Fig. 3A–B

(A) An AP radiograph shows a distal humeral telescoped allograft replacing the distal 10 cm of the humerus, secured with the long stem of an elbow replacement. (B) A lateral radiograph shows the distal humeral telescoped APC.

Fig. 4A–D

(A) Anteroposterior and (B) lateral radiographs show an uncemented expandable prosthesis with a side plate that underwent painful septic loosening. After the infection was treated by prosthetic removal and antibiotics systemically and locally, a telescoped allograft was used to reconstitute the proximal femur using the inverted technique. This impacted the shaft of a femoral allograft inside the medullary canal of the remaining proximal femur and secured it with a long-stemmed prosthesis. In postoperative (C) AP and (D) lateral radiographs, the allograft outline is highlighted by the dotted line. Cement was pressurized into the canal. Some extruded around the allograft and entered a short distance into the allograft-host interface (arrows).

Fig. 5A–D

(A) A preoperative radiograph shows circumferential radiolucency of a long-stemmed megaprosthesis. (B) An intraoperative film shows the allograft overlapping the host bone over a 5-cm segment. (C) A radiograph taken 1 month postoperatively shows the profound periosteal new bone formation and healing. (D) A film taken 5 years postoperatively shows full healing and remodeling of the allograft and the host.