Commentary & Perspective

Commentary & Perspective on
"Mennen Plate Fixation for the Treatment of Periprosthetic Femoral Fractures. A Multicenter Study of Thirty-six Fractures"
by Robbert J.P. Noorda, MD, and Paul I.J.M. Wuisman, MD, PhD

Commentary & Perspective by
Daniel J. Berry, MD*,
Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN

In the December 2002 issue of The Journal, Noorda and Wuisman reported the results of Mennen plate fixation for the treatment of thirty-six periprosthetic femoral fractures that occurred after hip and knee arthroplasty. They found nonunion and varus bending (20° to 30°) of the plate in ten (28%) of the thirty-six fractures; eight of the ten patients had a fracture of the plate. In the nine patients with a Johansson type-I fracture (a fracture proximal to the tip of the implant stem), the union rate was 100%, but for the remaining patients with unstable type-II or III fractures, the nonunion rate was 46%. At the conclusion of the article, Noorda and Wuisman stated: "Although good results were found in type-I fractures and in combination with revision procedures, we do not recommend the Mennen plate for the treatment of periprosthetic femoral fractures."

For treatment of patients with failed femoral implants who sustain a fracture around the stem, prosthesis revision usually is recommended and, in most of these cases, fracture fixation can be achieved with the implant itself serving as an intramedullary rod, with the adjunctive use of cerclage devices or cortical strut grafting to augment fracture stability. There are mechanical and biological problems when internal fixation is the primary form of fixation of these fractures. The fracture typically occurs in an area of stress concentration (the stem tip) and the bone quality in patients who suffer these fractures is often poor.

Internal fixation of periprosthetic fractures without revision of the prosthesis, whatever the specific fixation device chosen, usually is indicated in patients with an unstable periprosthetic fracture that occurs around the stem tip and is associated with a well-fixed, well-functioning stem. In these patients, nonoperative management results in high rates of malunion and nonunion. When the stem is retained, intramedullary devices cannot be used because the prosthesis fills a portion of the canal. Because of this limitation, the most common form of fixation used to treat these fractures has been application of a plate for fixation of the femur with cerclage in the area of the femoral stem. The Mennen plate is unique because its multiple malleable metal tines can be wrapped around the femur to provide fixation of the plate to the bone.

The important finding of this study is the high rate of failure of Mennen plate fixation for the treatment of unstable fractures around well-fixed implants, which suggests that the strength of the plate or the fixation, or both, is insufficient to provide reliable fracture-healing in this challenging patient population. A high union rate was seen only in patients who had revision arthroplasty concomitantly with fracture fixation, which probably renders the plate superfluous in most cases, and in patients with Johansson type I-fractures, which present fewer biomechanical challenges than do the more common and difficult type-II and III fractures. Noorda and Wuisman provided an excellent summary of data from eighteen published studies involving a total of 117 cases of Mennen plate fixation of periprosthetic fractures (see the electronic Appendix, Table E-1); examination of these data reveals a failure rate of 17% (twenty of 117), a rate only slightly better than that reported in this paper. Admittedly, the study by Noorda and Wuisman has methodological limitations that may have contributed to the high failure rate that they reported. First, theirs is a multicenter study involving thirty-six fractures treated at twenty-one institutions, which suggests that no single institution had a large experience with Mennen plate fixation. Thus, some failures may be attributable to each center's "learning curve." Second, the study group—consisting of twenty-eight periprosthetic fractures that occurred after total hip arthroplasty, one after a hemiarthroplasty of the hip, two around total knee arthroplasty, and five between a total hip arthroplasty and a total knee arthroplasty—is heterogenous. In five fractures, Mennen plate fixation was used after failure of other osteosynthesis techniques; in these circumstances, the viability and quality of the bone were probably already compromised. Nevertheless, despite the methodological limitations of the study, the authors' conclusion that this device cannot be recommended for the treatment of most unstable periprosthetic fractures of the femur seems justified.

Other methods of fixation have been reported to be more effective for treatment of these challenging fractures. Recently in The Journal, Haddad et al.¹ reported on forty periprosthetic femoral fractures around well-fixed femoral stems that were treated with either metal plate-fixation in combination with cortical onlay strut allografts or cortical onlay strut allografts alone; thirty-nine (98%) of the forty fractures united. I prefer to use a lateral femoral plate, which allows for use of both screws and cables in combination with an anterior cortical strut graft, for fixation of these fractures. This combination may optimize the mechanical fixation of the fracture and the biologic environment necessary for fracture-healing.

*The author did not receive grants or outside funding in support of the research or preparation of this manuscript. The author received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity (DePuy). In addition, commercial entities (DePuy, Zimmer) paid or directed, or agreed to pay or direct, benefits to a research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Haddad FS, Duncan CP, Berry DJ, Lewallen DG, Gross AE, Chandler HP. Periprosthetic femoral fractures around well-fixed implants: use of cortical onlay allografts with or without a plate. J Bone Joint Surg Am. 2002;84:945-50.