To the Editor:
We read with interest the article “Periprosthetic femoral condyle fracture after total knee arthroplasty and saline-coupled bipolar sealing technology” ( http://www.orthosupersite.com/view.aspx?rid=78553) in the January 2011 issue of ORTHOPEDICS. These 4 periprosthetic femoral fractures are unfortunate and problematic, but we believe the evidence implicating the saline-cooled bipolar sealing device as the primary cause of these fractures appears tenuous at best. It is speculation that thermal damage caused by the device affected the mechanical property of the bone, because histological examination of the specimen did not demonstrate any evidence of osteonecrosis. This lack of osteonecrosis is consistent with a recent study by Menendez et al,1 which revealed a notable lack of osteonecrosis when clinically relevant levels of bipolar radiofrequency were applied to ovine cortical bone.
The incidence of early postoperative femoral periprosthetic fractures is low and is usually related to intraoperative technical errors, weakened bone, or an early traumatic event such as a fall. Known risks factors include female sex, osteoporosis, rheumatoid arthritis, steroid use, anterior femoral notching, and intercondylar notch preparation with a posterior stabilized prosthesis.2 In reviewing the 4 cases, it is interesting that 3 of the patients were women, all with osteoporotic bone. The 1 male patient had a history of alcohol use, along with cardiac and pulmonary disease. All of these comorbidities affect the quality of the juxta-articular bone and potentially predispose them to postoperative fracture.
Understanding that the authors have a great deal of experience with posterior-stabilized total knee arthroplasty (TKA), we assume that the intercondylar notch was prepared appropriately. However, a tight fit during trial insertion or final implantation of the femoral component may be a source of an early nondisplaced fracture that propagated and displaced once the patient began to bear weight, especially in the presence of osteoporotic bone. Knowing that anterior notching has been implicated with fracture, it would have been beneficial to see the immediate postoperative lateral radiographs.
Periprosthetic femoral condyle fractures are admittedly frustrating and are associated with a high degree of patient morbidity. However, it is important to remember that correlation does not imply causation. There are several possible, previously reported factors that may have led to these fractures, and the evidence does not conclusively point to saline-coupled bipolar sealing technology as the primary culprit. We use this bipolar device on all our TKAs and find it to be a valuable adjunct for managing intraoperative blood loss. It is our impression that the true message of this article is the proper use of this device for a safe and efficacious outcome.
Giles R. Scuderi, MD
Alfred Tria, MD
- Menendez M, Ishihara A, Weisbrode S, Bertone A. Radiofrequency energy on cortical bone and soft tissue: a pilot study [published online ahead of print November 5, 2009]. Clin Orthop Relat Res. 2010; 468(4):1157–1164. doi:10.1007/s11999-009-1150-x [CrossRef]
- Su ET, DeWal H, Di Cesare PE. Periprosthetic femoral fractures above total knee replacements. J Am Acad Orthop Surg. 2004; 12(1):12–20.
We thank Drs Scuderi and Tria for their thoughtful comments. We agree that from this case series, there is no irrefutable evidence that implicates the use of saline-cooled bipolar sealing as the cause of these fractures. However, it cannot be ruled out, and, to the authors, the association was highly suspicious. After performing thousands of posterior-stabilized TKAs without periprosthetic femoral condyle fractures, we found this device to be the only change in the procedures in question. Osteonecrosis is only an end manifestation of various bony insults, and its absence could have been due to our intraoperative biopsy sampling error. Additionally, its absence alone should not fully exculpate lesser thermophysical alterations, intra- and extra-osseous vascular sealing, or other unknown potentially deleterious effects. Like Drs Scuderi and Tria, we find that this technology is highly efficacious at reducing blood loss and continue to use it during TKA, albeit to a much lesser extent over the synovium and periosteum covering the metaphyseal flare of the femoral condyles. Further, we agree that the take-home point of the article is not that it should be avoided but rather used with the same caution as standard electrocautery. As with any innovative device, surgeons should have a high level of suspicion with any unusual complications and should not wait for overwhelming evidence before adjusting their practices.
Vincent Y. Ng, MD
Lindsay Arnott, BS
Michael A. McShane, MD