Sat., 10/10/09 Knee/Tibia, Paper #79, 3:40 pm OTA-2009
Risk Factors for Failure of Locked Plate Fixation of Distal Femur Fractures: An Analysis of 305 Cases
William M. Ricci, MD1 (3, 4, 5A, 7-Smith &Nephew; 4, 7-AO, 4, 5A-Wright Medical
Technology, Inc.; 5A, 7-Synthes); Philipp N. Streubel, MD1 (n);
Saam Morshed, MD2 (7-Synthes); Cory Collinge, MD3 (n);
Sean E. Nork, MD2 (7-AO, Synthes, Smith &Nephew, Stryker, Zimmer);
Michael J. Gardner, MD1 (5A-Synthes, Expanding Orthopedics; 7-AO, Synthes,
Smith &Nephew);
1Washington University School of Medicine, Saint Louis, Missouri;
2Harborview Medical Center, Seattle, Washington, USA;
3Harris Methodist Fort Worth Hospital, Fort Worth, Texas, USA
Purpose: Locked plating has become a standard method to treat supracondylar femur fractures. To date, there are no large-scale investigations reporting risk factors for failure of this widely used treatment method. The goals of this study were to examine a large population of such cases to determine risk factors for complications (eg, nonunion, infection, and implant failure) and to provide technical recommendations (eg, plate length, number of screws).
Methods: 484 consecutive patients with supracondylar femur fractures (OTA 33) treated with lateral locked plates were retrospectively identified (IRB-approved) from 3 centers. 305 patients (57% female) with adequate follow-up had an average age of 58 years (range, 20-97). 87 had open fractures (29%), of which 78% were grade III. 21 of the 68 grade III open fractures had a plan for a staged bone graft (BG) due to a bone defect after débridement (average 7 cm). 33% of the entire cohort was obese, 19% diabetic, and 25% smokers. Characteristics of the fixation construct such as plate length and number and location of screws were distinguished for 3 regions of fixation: fixation over the proximal fragment, distal fragment, and zone of the fracture. Using multiple logistic regression models, risk factors for complications were identified as independent variables with P <0.05. Nonunion, infection, and implant failure were used as the dependent complication variables.
Results: Nonunion: 261 patients healed after the index procedure (86%), 26 developed a nonunion (9%), and 18 (6%) required a staged BG (4 healed prior to a planned BG). Diabetes was the only independent risk factor for nonunion (P = 0.001, analysis excluded those with a plan for staged BG). Deep infection (P <0.001), open fracture (P <0.001), and advanced age (P = 0.037) were independent risk factors for the occurrence of either nonunion or BG. Deep Infection: Deep infection occurred in 14 patients (5%). Male gender (P = 0.035) and a pedestrian-struck mechanism (P = 0.003) were significant independent risk factors. Implant Failure: 25 patients (8%) had implant failures, of which 15 occurred in the proximal fragment, 6 in the distal fragment, and 4 over the zone of the fracture. The independent risk factors for any implant failure were OTA A3 fracture pattern, diabetes, high body mass index, stainless steel plate, and shorter plate (P <0.05 for all). Proximal implant failure was 3 times less likely when the overall plate length was 10 holes or longer (2.5% vs 7.7%, P = 0.03). Proximal failure was less likely with use of more proximal screws (P <0.05), with an average of 4.3 screws in the failures versus 4.7 in nonfailures. When 8 or more plate holes covered the diaphyseal fragment, fixation failure was 10 times less likely compared to use of 7 or fewer proximal plate holes (0.7% vs 8.9%, P <0.001). Proximal screw density (percentage of filled holes) of less than 60% was associated with a fourfold lower failure rate than a screw density of greater than 60% (1.9% vs 8.3%, P = 0.02).
Conclusions: The identified risk factors for healing and complications—diabetes, open fracture, deep infection, and advanced age—are useful when considering prognosis, but these are, for the most part, out of surgeon control. In contrast, several of the identified risk factors for implant failure may be affected by relatively minor technical modifications. We recommend the use of relatively long plates, at least 10 holes proximal to the articular cluster, and at least 8 holes proximal to the fracture. It appears that using at least 5 screws proximally can reduce failure risk, but requires an adequate plate length to maintain screw density below 60%.
Disclosure: (n=Respondent answered 'No' to all items indicating no conflicts; 1=Board member/owner/officer/committee appointments; 2=Medical/Orthopaedic Publications; 3=Royalties; 4=Speakers bureau/paid presentations; 5A=Paid consultant or employee; 5B=Unpaid consultant; 6=Research or institutional support from a publisher; 7=Research or institutional support from a company or supplier; 8=Stock or Stock Options; 9=Other financial/material support from a publisher; 10=Other financial/material support from a company or supplier).
• 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