We undertook this review to better understand the frequency, location, timing, and management of ipsilateral limb fractures associated with compressive osseointegration reconstructions. The effect of such fractures on prosthetic retention, limb preservation, and ambulatory status was also studied.
Limitations of this study include its size, length of followup, and focus on one type of endoprosthesis. The limited size and followup make it difficult to draw definitive conclusions regarding the time frame for fractures to occur. Experience with the Compress®
device reported here is not directly applicable to periprosthetic fractures in arthroplasty patients, or even in the majority of tumor patients, who continue to receive conventional stemmed implants. Generalization of these results to centers less experienced in the use of compressive osseointegration techniques may not be immediately possible. Furthermore, the study population described here consists largely of young tumor patients, whereas the Compress®
device is being increasingly used for revision arthroplasty patients, for whom advanced age and osteoporosis may well signal a higher periprosthetic fracture risk. Another limitation is the lack of firm data regarding risk analysis of periprosthetic fracture per patient-year [24
]. However, the paper reports an experience of more than 200 patients treated over a 12-year period by four surgeons at two major sarcoma centers. In addition, the data would seem to confirm the acceptable risk profile of compressive osseointegration technology for endoprosthetic fixation with respect to the specific issues of periprosthetic fracture incidence, management, and prosthetic retention.
The most robust data regarding periprosthetic fractures from the arthroplasty literature deal with femoral fractures after total hip replacement, for which the 10-year probability of fracture has been estimated to be 0.64% [24
]. The annual incidence is thought to vary between 0.045% and 0.13%, with a tendency for the incidence to increase over time [24
]. Treatment is often complex [26
], and the seriousness of this complication is highlighted by the 1-year mortality rate for such patients, which in one study was 12% for those undergoing revision arthroplasty and 33% for those undergoing ORIF [6
Comparable information regarding incidence, treatment, and outcomes for patients with periprosthetic fractures after megaprosthetic reconstructions, most often performed for tumors, is lacking. Most large series of intermediate to long-term results of endoprosthetic implants highlight implant survivorship, but failure due to periprosthetic fracture is often not specifically commented upon [7
]. Although Inglis and Walker reported a periprosthetic fracture rate of 37.5% of fixed hinge devices used to revise failed hinged implants [19
], most recent papers commenting on periprosthetic fracture risk in primary tumor reconstructions using rotating hinge devices report rates of 0.3% to 6.1% (Table ) [1
]. Given the relatively low frequency of this complication, and the wide variety of implants reported upon, little has been described regarding optimal surgical management or treatment results of these fractures.
Studies of periprosthetic fractures associated with endoprostheses
As compared to historical data regarding arthroplasty patients as well as cancer patients having conventional cemented and uncemented stems, we believe the Compress®
device provides acceptable results in terms of the incidence of periprosthetic fractures in a generally young tumor population which is nonetheless subject to risk factors of osteoporosis (secondary to preoperative disuse and the effects of chemotherapy and radiation) and high activity demands. When a fracture does occur, Compress®
technology offers the distinct advantage of comparatively straightforward revision, given the ease of extraction of the intramedullary portion of the device, and the minimal amount of bone (as little as 2 to 4 cm) that needs to be resected before implantation of a new device. Furthermore, short metaphyseal-epiphyseal fragments (43 mm or longer) remaining after fracture can still be salvaged with a short anchor plug, thus obviating the need for conversion to a total femoral replacement [30
]. Although femoral fractures above the anchor plug can be expected to occur at any time in the patient’s life if sufficient force is applied, our finding that all periprosthetic fractures occurred within 2 years of surgery is of potential importance for predicting the risk of this complication, since the opposite is expected to be true for typical arthroplasties and megaprostheses [24
]. This difference can be attributed to the cortical hypertrophy engendered by compressive osseointegration forces; as demonstrated by Avedian et al. [2
], the Compress®
device provides, stability and bone growth at the prosthetic interface over the first 6 to 12 months, effectively sealing the endosteal canal to particulate debris [23
]. By contrast, stress shielding and osteolysis are expected to be ever-increasing problems for many tumor megaprosthetic stems, thereby increasing the risk for aseptic loosening and periprosthetic fracture with time. Finally, we observed no instances of mechanical breakage of the Compress®
device, a finding that should be considered when comparing conventional endoprosthetic devices, for which implant fracture has been reported to be as high as 10% [14
]. Although case-matched cohort studies are of some utility in comparing compressive osseointegration technology to standard stem fixation [5
], long term prospective studies are desirable in order to elucidate this and other complications before any particular reconstructive approach can be definitively endorsed.