Tibial Stem Extension versus Standard Configuration in Total Knee Arthroplasty: A Biomechanical Assessment According to Bone Properties

Abstract

Background and Objectives: This study’s purpose was to examine the benefit of using a tibial extension in the primary operation of total knee arthroplasty (TKA). This is important because it is not a common practice to use the extension in a primary TKA, a standard configuration offering sufficient stability and good long-term survivorship. The following question arises: which situation requires the use of a standard configuration implant (without a stem) and which situation requires using the extension? Materials and Methods: The opportunity to use the tibial extension in the primary TKA was analyzed in correlation to the tibial bone structural properties. Using finite elements (FEs), the virtual model of the tibial bone was connected to that of the prosthetic implant, with and without a stem, and its behavior was analyzed during static and dynamic stresses, both in the situation in which the bone had normal physical properties, as well as in the case in which the bone had diminished physical properties. Results: The maximum stress and displacement values in the static compression regime show that adding a stem is only beneficial to structurally altered bone. Compression fatigue was reduced to almost half in the case of altered bone when adding a stem. Dynamic compression showed slightly better results with the tibial stem in both healthy and degraded bone. Conclusions: It was concluded that, if the bone is healthy and has good structural properties, it is not necessary to use the tibial extension in the primary operation; and if the bone has diminished physical properties, it is necessary to use the tibial extension at the primary operation, enhancing the stability, fixation, and implant lifespan.

Proximal Tibial Sliding Osteotomy as an Alternative Solution for Patients With Proximal Tibial Bone Defect After Neglected Tibial Plateau Fractures Undergoing Total Knee Arthroplasty: A Case Report

“…In severe cases like this case, arthroplasty is a good treatment option (6) . The presence of large defects more than 20% with depressed more than 16 mm, is not possible to treat with screw and bone graft augmentation alone (7) , ideally this case would require additional special implants such as metal augmentation and longer stems (2,8) . However, it should not be forgotten that in suburban hospitals with limited funding, we must also think about ways to reduce the costs (7) .…”

The Biomechanical Analysis of Tibial Implants Using Meshless Methods: Stress and Bone Tissue Remodeling Analysis

“…where ρ 0 corresponds to the density of compact bone, approximately 2.1 g/cm 3 , and porosity p is calculated from V holes /V sample , where V holes is the total volume of holes. The apparent density holds significance in its connection to the mechanical attributes of bone tissue, specifically the elasticity modulus and ultimate stress.…”

“…TKA can encompass the surface of up to three bones: the femur, the patella, and the tibia; however, the latter is the area where most injuries leading to this surgical procedure occur [2]. In certain cases, for enhanced implant fixation and stability, a cylindrical extension known as the tibial stem is incorporated at the distal end of the tibial metal component whose primary function is to increase implant stability, particularly in challenging cases, by minimizing micromovements at the bone-implant interface, thereby mitigating the risk of aseptic loosening [3]. These tibial extensions come in various lengths and widths and can be secured through different methods, including total cementation, proximal cementation only, or a press-fit approach without the use of cement [3].…”

“…In certain cases, for enhanced implant fixation and stability, a cylindrical extension known as the tibial stem is incorporated at the distal end of the tibial metal component whose primary function is to increase implant stability, particularly in challenging cases, by minimizing micromovements at the bone-implant interface, thereby mitigating the risk of aseptic loosening [3]. These tibial extensions come in various lengths and widths and can be secured through different methods, including total cementation, proximal cementation only, or a press-fit approach without the use of cement [3]. The existence and design of the tibial extension, including its size and method of fixation, can induce a phenomenon referred to as stress shielding, resulting in bone loss in the regions most affected, which may weaken the implant fixation, requiring the placement of a new prosthesis [4][5][6][7].…”

The additional tibial stem extension is not mandatory for the stability of 5 mm metal block augmented tibial prosthesis construct in primary total knee arthroplasty: 5-year minimum follow-up results

“…In addition, it can cause stem tip pain, which affects patient dissatisfaction [ 38 ]. Finally, when revision surgery is needed, large bone resection might be necessary, which may be followed by low bone density and technical problems such as fixation of revision implant [ 39 , 40 ].…”