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

Abstract

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.]

Operative Fixation of a Humeral Shaft Periprosthetic Fracture After IlluminOss

“…The PBSS implant in this patient could have fractured during lag screw insertion because of the decreased cross-sectional area of the medullary canal at the distal end of the humeral shaft. One study reported that PBSS implants were 3 times more likely to fail at the distal humeral shaft, possibly because of the decreased cross-sectional area of the implant in the distal humerus compared with metaphyseal and proximal regions 9 .…”

“…The IlluminOss PBSS has shown promising clinical results for treatment of a plethora of upper and lower extremity impending, pathologic, and acute fractures 4,6,9,11,13,16,28 . The decision to use the IlluminOss PBSS in this patient was supported by early findings.…”

“…Although the proposed benefits of the IlluminOss PBSS are the proposed ease of removal and capability to use a combined plate/screw construct 10 , we found this to be more challenging than anticipated because we were unable to remove the implant from the medullary canal and part of the PBSS implant fractured when attempting to insert a lag screw across the spiral distal humeral shaft fracture. Basile et al reported a case of fixation of a refractory humeral nonunion with PBSS and internal fixation; however, the PBSS and hardware were implemented during the same surgery [8][9][10] .…”

“…Despite compliance with Sarmiento bracing and non-weight-bearing restrictions, preoperative fluoroscopic imaging revealed that the patient sustained a pathologic, nondisplaced fracture at the level of the lytic lesion. The operating surgeon elected to use the IlluminOss PBSS as indicated and described in previous studies involving fixation of the humerus 9,10,16,17 . Although using a supplemental plate or screw was considered given the large lytic lesion, it would have required an additional incision and therefore place the patient at a higher risk of wound complications, given his advanced age and anticipated postoperative radiation.…”

“…When compared with traditional nailing of long bones, the PBSS offers less artifact on postoperative advanced imaging, features less interference with postoperative radiation, and can provide torsional stability without the use of interlocking screws depending on the implant's three-dimensional shape and fracture characteristics 4,6,7 . For additional stability, several authors have described surgical techniques that implement PBSS alone, PBSS with supplemental screws, or a combined construct with a plate and screws [8][9][10] .…”