Stability of the Posteromedial Fragment in a Tibial Plateau Fracture

Abstract

The posteromedial fragment in tibial plateau fractures is considered unstable and requires specific fixation. However, if not loaded by the femur, it may remain stable and not require additional fixation. Our purpose was to determine the size of the posteromedial fragment that would remain unloaded by the femoral-tibial contact area, as a function of fracture line orientation and knee flexion angle. Seven human cadaveric knees with intact capsule and ligaments were mounted in a mechanical rig and flexed from 0 to 30, 90, 105, and 120 degrees of flexion. The fiducial points and articular surfaces were digitized, and 3-dimensional software models of the knees at each flexion angle were created. The femoral-tibial contact areas were determined using the software under high- and low-load conditions. Posteromedial fragments of various sizes and fracture line orientations relative to the posterior femoral condylar axis (PFCA) were modeled, and their locations relative to contact areas were determined. The size of unloaded fragments decreased with increased flexion angle. Fragments occupying 60% of the medial plateau were loaded at all angles, but fragments with 30% of the plateau became loaded at 90 degrees under high load and 120 degrees under low load. Fracture line orientations of 0 to 20 degrees external rotation relative to PFCA allowed for the largest fragments to remain unloaded. The size of posteromedial tibial plateau fracture fragment that remains unloaded by the femur varies with knee flexion angle and fracture line orientation. This may have implications for the management of posteromedial tibial plateau fractures.

Keywords

tibial plateau fracture - Posteromedial fragment - Contact area - fracture stability

• References

• 1 Higgins TF, Kemper D, Klatt J. Incidence and morphology of the posteromedial fragment in bicondylar tibial plateau fractures. J Orthop Trauma 2009; 23 (1) 45-51
• 2 Barei DP, O'Mara TJ, Taitsman LA, Dunbar RP, Nork SE. Frequency and fracture morphology of the posteromedial fragment in bicondylar tibial plateau fracture patterns. J Orthop Trauma 2008; 22 (3) 176-182
• 3 De Boeck H, Opdecam P. Posteromedial tibial plateau fractures. Operative treatment by posterior approach. Clin Orthop Relat Res 1995; (320) 125-128
• 4 Higgins TF, Klatt J, Bachus KN. Biomechanical analysis of bicondylar tibial plateau fixation: how does lateral locking plate fixation compare to dual plate fixation?. J Orthop Trauma 2007; 21 (5) 301-306
• 5 Weil YA, Gardner MJ, Boraiah S, Helfet DL, Lorich DG. Posteromedial supine approach for reduction and fixation of medial and bicondylar tibial plateau fractures. J Orthop Trauma 2008; 22 (5) 357-362
• 6 Wu CC, Tai CL. Plating treatment for tibial plateau fractures: a biomechanical comparison of buttress and tension band positions. Arch Orthop Trauma Surg 2007; 127 (1) 19-24
• 7 Ratcliff JR, Werner FW, Green JK, Harley BJ. Medial buttress versus lateral locked plating in a cadaver medial tibial plateau fracture model. J Orthop Trauma 2007; 21 (7) 444-448
• 8 Barei DP, Nork SE, Mills WJ, Henley MB, Benirschke SK. Complications associated with internal fixation of high-energy bicondylar tibial plateau fractures utilizing a two-incision technique. J Orthop Trauma 2004; 18 (10) 649-657
• 9 Hill PF, Vedi V, Williams A, Iwaki H, Pinskerova V, Freeman MA. Tibiofemoral movement 2: the loaded and unloaded living knee studied by MRI. J Bone Joint Surg Br 2000; 82 (8) 1196-1198
• 10 Iwaki H, Pinskerova V, Freeman MA. Tibiofemoral movement 1: the shapes and relative movements of the femur and tibia in the unloaded cadaver knee. J Bone Joint Surg Br 2000; 82 (8) 1189-1195
• 11 Walker PS, Sussman-Fort JM, Yildirim G, Boyer J. Design features of total knees for achieving normal knee motion characteristics. J Arthroplasty 2009; 24 (3) 475-483
• 12 Yildirim G, Walker PS, Sussman-Fort J, Aggarwal G, White B, Klein GR. The contact locations in the knee during high flexion. Knee 2007; 14 (5) 379-384
• 13 Walker PS, Yildirim G, Sussman-Fort J, Klein GR. Relative positions of the contacts on the cartilage surfaces of the knee joint. Knee 2006; 13 (5) 382-388
• 14 Gösling T, Schandelmaier P, Marti A, Hufner T, Partenheimer A, Krettek C. Less invasive stabilization of complex tibial plateau fractures: a biomechanical evaluation of a unilateral locked screw plate and double plating. J Orthop Trauma 2004; 18 (8) 546-551
• 15 Mueller KL, Karunakar MA, Frankenburg EP, Scott DS. Bicondylar tibial plateau fractures: a biomechanical study. Clin Orthop Relat Res 2003; (412) 189-195
• 16 Egol KA, Su E, Tejwani NC, Sims SH, Kummer FJ, Koval KJ. Treatment of complex tibial plateau fractures using the less invasive stabilization system plate: clinical experience and a laboratory comparison with double plating. J Trauma 2004; 57 (2) 340-346
• 17 Egol KA, Tejwani NC, Capla EL, Wolinsky PL, Koval KJ. Staged management of high-energy proximal tibia fractures (OTA types 41): the results of a prospective, standardized protocol. J Orthop Trauma 2005; 19 (7) 448-455 , discussion 456
• 18 Barei DP, Nork SE, Mills WJ, Coles CP, Henley MB, Benirschke SK. Functional outcomes of severe bicondylar tibial plateau fractures treated with dual incisions and medial and lateral plates. J Bone Joint Surg Am 2006; 88 (8) 1713-1721
• 19 Berkson EM, Virkus WW. High-energy tibial plateau fractures. J Am Acad Orthop Surg 2006; 14 (1) 20-31
• 20 Li G, DeFrate LE, Park SE, Gill TJ, Rubash HE. In vivo articular cartilage contact kinematics of the knee: an investigation using dual-orthogonal fluoroscopy and magnetic resonance image-based computer models. Am J Sports Med 2005; 33 (1) 102-107
• 21 Walker PS, Erkman MJ. The role of the menisci in force transmission across the knee. Clin Orthop Relat Res 1975; (109) 184-192
• 22 Zielinska B, Donahue TL. 3D finite element model of meniscectomy: changes in joint contact behavior. J Biomech Eng 2006; 128 (1) 115-123
• 23 Gardner MJ, Yacoubian S, Geller D , et al. The incidence of soft tissue injury in operative tibial plateau fractures: a magnetic resonance imaging analysis of 103 patients. J Orthop Trauma 2005; 19 (2) 79-84
• 24 Walker PS, Hajek JV. The load-bearing area in the knee joint. J Biomech 1972; 5 (6) 581-589
• 25 Kääb MJ, Ito K, Rahn B, Clark JM, Nötzli HP. Effect of mechanical load on articular cartilage collagen structure: a scanning electron-microscopic study. Cells Tissues Organs 2000; 167 (2–3) 106-120
• 26 Herberhold C, Faber S, Stammberger T , et al. In situ measurement of articular cartilage deformation in intact femoropatellar joints under static loading. J Biomech 1999; 32 (12) 1287-1295
• 27 Cohen ZA, McCarthy DM, Kwak SD , et al. Knee cartilage topography, thickness, and contact areas from MRI: in-vitro calibration and in-vivo measurements. Osteoarthritis Cartilage 1999; 7 (1) 95-109
• 28 Ahmed AM, Burke DL. In-vitro measurement of static pressure distribution in synovial joints—Part I: Tibial surface of the knee. J Biomech Eng 1983; 105 (3) 216-225
• 29 Walker PS, Heller Y, Cleary DJ, Yildirim G. Preclinical evaluation method for total knees designed to restore normal knee mechanics. J Arthroplasty 2011; 26 (1) 152-160