Sat., 10/10/09 Knee/Tibia, Paper #85, 4:26 pm OTA-2009
CT Analysis and Functional Outcomes of Tibial Plateau Fractures Treated with ORIF and a Calcium Sulfate / Calcium Phosphate Composite Graft
William M. Ricci, MD1 (3, 4, 5A, 7-Smith & Nephew; 4, 7-AO, 4, 5A-Wright Medical
Technology, Inc.; 5A, 7-Synthes); J. Tracy Watson, MD2 (7-Wright Medical);
Joseph Borrelli, MD3 (5A-Wright Medical Technology, Inc.; 7-AO, Biomet, KCI, Zimmer,
Wyeth, Wright Medical Technology, Inc., Synthes, Inc., Stryker, Smith &Nephew, Sanofi-Aventis,
Ceraver Osteal, Ortho Biotech, Orthofix, Inc., Orthologic, Orthopaedic Scientific Research Fndtn, Orthosoft, Ossur, Osteobiologics, Inc., Osteotech); Timothy Weber, MD4 (7-Wright Medical);
Robert H. Choplin, MD, FACR5 (7-Wright Medical); Scott A. Persohn, RT (R), (MR)5 (7-Wright Medical);
1Washington University, Saint Louis, Missouri, USA; 2Saint Louis University, St. Louis, Missouri, USA;
3University of Texas SW, Dallas, Texas, USA; 4OrthoIndy, Indianapolis, Indiana, USA;
5Indiana University, Indianapolis, Indiana, USA
Purpose: Bone grafting of subchondral voids during open reduction and internal fixation (ORIF) of tibial plateau fractures is commonly performed. The goals of such grafting are to help support the articular reduction during fracture healing and to provide bone regeneration within the void. Prior studies of the plateau have evaluated articular reduction and bone regeneration by use of plain radiography. The primary goals of the current study were to determine the articular reduction and bone regeneration over time, using a CT methodology. The secondary goal was to determine functional outcomes.
Methods: 30 patients with unilateral tibial plateau fractures (OTA 41A-C) were enrolled in a prospective, IRB-approved, multicenter single-cohort study. The operative protocol included ORIF and defect augmentation with a calcium sulfate/calcium phosphate composite bone-graft substitute. Plain radiographs and CT scans at 12 and 24 weeks postoperatively were compared to identical imaging performed immediately postoperatively. CT views were precisely aligned so that all measurements were made at nearly identical geometric positions. CT analysis was performed by an independent musculoskeletal radiologist who quantified change over time in the articular reduction (maximum depression) and bone regeneration (density). Maximum depression was defined as the distance between the transcondylar line and the lowest point of the articular surface. Bone regeneration was defined as the density, in Hounsfield units (HU), of the grafted region. Functional outcome was assessed using the Short Musculoskeletal Functional Assessment (SMFA) scores.
Results: 28 patients were available for follow-up. Maximum depression, as measured by CT, resulted in a mean change from baseline of 1.06 (range, –2.4 to 21.4) and 1.79 mm (range, –2.3 to 23.3) at 12 and 24 weeks. Following removal of 2 outliers, these values were 0.13 (range, –2.4 to 5.1) and 0.34 mm (range, –2.3 to 4.7). Quantitative density measures averaged 1444, 905, and 605 HU at immediate postoperative, 12, and 24 weeks, respectively. This change in density toward that of normal bone over time suggests a process of resorption of the graft material followed by new bone formation. SMFA activity scores improved 37 points from baseline.
Conclusions: Critical evaluation with CT showed that a protocol of ORIF plus a calcium sulfate/calcium phosphate composite bone-graft substitute provides maintenance of perioperative
reduction to within 2 mm, with the subchondral bone void returning toward a density of normal bone. Consideration should be given to CT in order to most accurately characterize reduction maintenance, as well as new bone formation, in plateau fractures.
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