Session VI - Femur

Sat., 10/18/08 Femur, Paper #55, 10:28 am OTA-2008

Titanium versus Stainless Steel Locked Plates for Distal Femur Fractures: Is There Any Difference?

Robert J. Gaines, MD (n); Roy Sanders, MD (a-DJ Orthopaedics, Encor Medical,
Link Orthopaedics, Medtronic Sofamor Danek, Pfizer, Synthes, Tornier, Twin Star Medical,
Zimmer; a,c-DePuy, A Johnson & Johnson Company; a,c-Stryker; a,c,e- Smith + Nephew;
c-Linvatec); H. Claude Sagi, MD (a,b,c,e-Smith + Nephew; b-AO; b,e-Stryker; a,e-Synthes);
George J. Haidukewych, MD (a,b,c,e-DePuy, A Johnson & Johnson Company; d-Surmodics);
Orthopedic Trauma Service, Florida Orthopedic Institute, Tampa, Florida, USA

Background: Locked plating has enjoyed widespread popularity despite a paucity of available literature regarding its complications. Controversy surrounds the ideal material for locking plates, which are often used for fractures that will undergo cyclic loading with a long working length due to metaphyseal comminution. Both stainless steel and titanium locked plates are available; however, no published data are available comparing the performance of these implants. The purpose of this study was to compare the rates of union and secondary surgery in a large, consecutive, unselected group of distal femur fractures comparing stainless steel and titanium locking implants.

Methods: Between 1999 and 2007, 135 patients with 139 fractures of the distal femur were treated with a locked plate at our Level 1 trauma center. Patient data were prospectively collected as part of our trauma registry. Follow-up to union or a minimum of 6 months was available for 109 patients with a mean age of 55 years. 41% of fractures were open, and 59% were closed. Plates were subdivided into categories based on the substrate material as titanium (LISS [Synthes] and Polyax [Depuy]) or stainless steel (Synthes locking condylar buttress plate [CBP], Periloc [Smith & Nephew]). The variables of patient age, length of follow- up, sex, smoking, OTA fracture classification, alignment, and quality of reduction were statistically similar in both groups. Nonunion was defined as a lack of fracture healing on sequential radiographs by 6 months postoperatively, or hardware breakage. Open fractures with massive segmental bone loss with planned secondary bone grafting were excluded.

Results: The nonunion rate for the group as a whole was 9 of 109 (8%). When one compares the titanium plates (LISS and Polyax) to the stainless steel locking plates (locking CBP and Periloc), the nonunion rates were 7% and 23%, respectively (P = 0.05). The time to union in the remaining fractures was not significant (P = 0.19).

Conclusions: The overall nonunion rate for stainless steel was significantly higher than for titanium (p=.05). When one subanalyzes closed fractures only, the difference was not significant (p=0.6). For open fractures, the difference was significant, with titanium performing better (p=.05). When one compares outcomes for plates from a single manufacturer, the nounion rate for LISS was lower than for the stainless locking distal femoral plate, this difference was highly significant (p=.006). Our data suggests that their may be a difference in union rates between titanium and stainless steel locking plates, especially in open fractures that may challenge the fixation for longer periods of time. The stiffer nature of the stainless constructs may contribute to the increased nonunion rates we observed. Further studies are needed to definitively answer the question about which locked plate substrate material performs better.

Significance: The ideal substrate material for locked plates remains undefined, and construct stiffness and stress shielding concerns remain; however, this study demonstrates a significantly higher rate of nonunion for stainless steel locked plates when compared to titanium implants.

If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts disclosed, and *disclosure not available at time of printing.

• The FDA has not cleared this drug and/or medical device for the use described in this presentation   (i.e., the drug or medical device is being discussed for an “off label” use).  ◆FDA information not available at time of printing. Δ OTA Grant.