Posters— Surgical Treatment of Sarcomas

RECENT EXPERIENCE WITH THE ComPreSs® DEVICE FOR COMLIANT FIXATION OF ONCOLOGIC ENDOPROSTHESES

O’Donnell RJ,^1,2 Martin DL,¹ Silverstein RM,² Johnston JO¹ (¹University of California, San Francisco, Department of Orthopaedic Surgery, Orthopaedic Oncology Service, 1701 Divisadero St., Suite 280, San Francisco, CA 94115-1652 and ²The Permanente Medical Group, Inc., Department of Musculoskeletal Oncology, 1200 El Camino Real, South San Francisco, CA 94080-3299)

Purpose: To determine the early survivorship of the ComPreSs® (CPS) prosthesis for compliant endoprosthetic fixation of massive oncologic defects.

Methods: A retrospective review of CPS implants was undertaken. Results with respect to prosthetic failure, local recurrence, metastatic disease, and death were studied. Radiographs were analyzed to ascertain evidence of prosthetic loosening.

Results: Twenty-eight consecutive cases comprising the entire experience of a single surgeon with the ComPreSs® prosthesis were reviewed. Follow-up averaged 1.43 years (Range 0.25 – 3.92). There were 18 male and 10 female patients with average age 30 years (Range 12-68). There were 21 primary oncologic cases, 6 revision oncologic cases, and 1 post-traumatic case. Osteosarcoma (12 cases) was the most common diagnosis. Prosthetic locations included: distal femur (18), proximal tibia (5), distal humerus (3), and proximal femur (2).

There was only one (1/28, 3.6%) mechanical distal femoral prosthetic failure at three months leading to successful revision CPS surgery. There was one deep infection treated with debridement, antibiotics, and prosthetic retention. There were two local recurrences (osteosarcoma, dedifferentiated chondrosarcoma with pathologic fracture) requiring amputation at 13 and 20 months post-operatively. Both implants were firmly fixed; both patients developed metastatic disease. There were no other metastases. There were no deaths. All remaining prostheses have continuous radiographic evidence of stable osteointegration.

Discussion: The ComPreSs® implant has proven to be versatile, durable, and effective for primary and revision oncologic indications. The CPS design attempts to avoid problems of loosening and stress-shielding encountered with both cemented and porous-coated stems conventionally used in limb salvage reconstructions. Rigid fixation at the prosthetic-bone interface prevents motion, allowing osteointegration and sealing the canal from particulate debris. High compliance afforded by the washers works to avert stress shielding. This is expected to enhance long-term prosthetic survival. A multi-center FDA IDE study of the distal femoral CPS prosthesis is now underway.