Porous metaphyseal cones can be used for fixation in revision total knee arthroplasty (rTKA) and complex TKAs. This metaphyseal fixation has led to some surgeons using shorter cemented stems instead of diaphyseal engaging cementless stems with a potential benefit of ease of obtaining proper alignment without being beholden to the diaphysis. The purpose of this study was to evaluate short term clinical and radiographic outcomes of a series of TKA cases performed using 3D-printed metaphyseal cones. A retrospective review of 86 rTKAs and nine complex primary TKAs, with an average age of 63.2 years (SD 8.2) and BMI of 34.0 kg/m2 (SD 8.7), in which metaphyseal cones were used for both femoral and tibial fixation were compared for their knee alignment based on the type of stem used. Overall, 22 knees had cementless stems on both sides, 52 had cemented stems on both sides, and 15 had mixed stems. Postoperative long-standing radiographs were evaluated for coronal and sagittal plane alignment. Adjusted logistic regression models were run to assess malalignment hip-knee-ankle (HKA) alignment beyond ± 3° and sagittal alignment of the tibial and femoral components ± 3° by stem type.Aims
Methods
Porous metaphyseal cones are increasingly used for fixation in revision total knee arthroplasty (RTKA). Both cemented shorter length stems and longer diaphyseal engaging stems are currently utilized with metaphyseal cones with no clear evidence of superiority. The purpose of this study was to evaluate our experience with 3D printed titanium metaphyseal cones with both short cemented and longer cementless stems from a clinical and radiographic perspective. In total 136 3D printed titanium metaphyseal cones were implanted. The mean patient age was 63 and 48% were female. The mean BMI was 33 and the mean ASA class was 2.5. There were 42 femoral cones in which 28 cemented and 14 cementless stems were utilized. There were 94 tibial cones in which 67 cemented and 27 cementless stems were utilized. The choice for stem fixation was surgeon dependent and in general cones were utilized for AORI type 2 and 3 bone defects on the femur and tibia. The most common fixation scenario was short cemented stems on both the femur and tibia followed by cemented stem fixation on the tibia and cementless fixation on the femur. Clinical data such as revision, complication, and PRO was collected at last follow-up (minimum follow-up 1 year). Radiographic analysis included cone bony ingrowth and coronal and sagittal alignment on long-standing radiographs. Descriptive statistics were used to compare demographics between patients who had malalignment (HKA beyond +/− 3 degrees and flexion/extension beyond +/− 3 degrees). Adjusted logistic regression models were run to assess malalignment risk by stem type.Introduction
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