Early Experience in Pathologic Humerus Fracture Treated With the Photodynamic Bone Stabilization System Shows Limitations Related to Patient Selection.

Impending and complete pathologic fractures often necessitate surgical fixation. Traditional orthopedic implants are commonly used, achieving clinically acceptable outcomes, but their metallic composition can impair radiographic evaluation and affect radiation treatments. Recognition of these concerns led to the development of radiolucent implants such as the minimally invasive Photodynamic Bone Stabilization System (PBSS; IlluminOss Medical Inc), featuring a light cured polymer contained within an inflatable balloon catheter. Two participating hospitals in one health care system reviewed cases using the PBSS implant. Twenty-five patients with 29 impending or pathologic fractures in the proximal radius or humerus from metastatic carcinoma, myeloma, lymphoma, and melanoma were identified. Clinical charts and imaging were reviewed to determine the status of the implant at final follow-up as well as complications. For analysis, a chi-square test was used for nominal variables and a t test was used for continuous variables. Eleven of the 25 patients were alive with disease at the time of analysis. Eight of 29 (27.5%) implants failed. Five of 25 (20%) patients required repeat surgery due to complications, including 3 revision open reduction and internal fixations, 1 open reduction and internal fixation for a periprosthetic fracture, and 1 screw removal. Five of the 9 cases (56%) (P=.03) with lesions in the distal humeral shaft had breakage of the implant by final follow-up, compared with 3 of 20 cases (15%) (P=.03) elsewhere in the humerus; no failures were seen in the radius. One of 4 patients (25%) also had failure in the surgical neck, although this did not reach significance. Five patients were noted to have progression of disease on follow-up radiographs, with 4 failures in patients with progression. The PBSS implants potentially allow improved surveillance of fracture healing and tumor recurrence along with decreased scattering of radiation during treatment. Unfortunately, there may be a higher rate of mechanical failures, particularly for lesions involving the distal humerus. This may be due to decreased cross-sectional area of the implant in this region as compared with the metaphyseal and proximal regions. Caution should be exercised when treating distal humeral pathologic fractures with large lytic lesions where the underlying disease process is not well controlled. [Orthopedics. 2021;44(3):154-159.].