Postoperative mechanical alignment analysis of total knee replacement patients operated with 3D printed patient specific instruments: A Prospective Cohort Study

Abstract

ObjectiveTotal knee replacement (TKR) is a surgical treatment for final stage gonarthrosis. The lifespan of the prosthetic implants used in TKR surgery is a major interest for the orthopaedic research community.Previously, proper implant alignment of the implants has been advocated for longevity of the TKR surgery. Recently, patient-specific (PSI) instruments have been proposed to improve the mechanical alignment of the TKR by permitting better implant positioning over conventional TKR surgery. The aim of this study is to compare the mechanical alignment results of patients operated with PSIs and conventional instruments.MethodsTwo groups of 20 patients chosen in a quasi-random manner have been compared in this study. In the first group femoral distal and tibial osteotomies were made by a PSI which was produced by the patients' computed tomography scans. All osteotomies in the control group were made with the TKR set's routine instruments by conventional means. Patients' preoperative and postoperative mechanical femorotibal angles (mFTA), femoral coronal angles (FCA), tibial coronal angles (TCA) were measured and the number of outliers which showed more than 3° of malalignment were counted in both groups for comparison.ResultsThe average postoperative mFTA was found to be 2.09° for the PSI group and in was found to be 2.84° for the control which was not statistically significant. The comparison of postoperative FCA and TCA also did not show significant difference between the groups. The number of outliers showing more than 3° of malalignment per group were found to be 1 out of 20 (5%) for the PSI group and 7 out of 20 (35%) for the control which was statistically significant.ConclusionIn this study patient-specific instrumentation provided significantly better mechanical alignment compared to conventional TKR for the frequency of outlier cases with malalignment beyond 3°. PSI proved no significant difference when the groups were compared for mFTA, FCA and TCA. Our findings support that PSI may improve TKR alignment by improving the ratio of the outlier patients with marked malalignment.Level of EvidenceLevel III, Therapeutic Study.

Deep 3D Convolutional Networks to Segment Bones Affected by Severe Osteoarthritis in CT Scans for PSI-Based Knee Surgical Planning

“…In synthesis, improvements in the segmentation in terms of Dice, Se or PPV does not necessarily mean an improvement of the clinical value of segmentation. As a final remark, we highlight that the role of the PSI surgical technique has been topic of many debates with no general consensus about the accuracy and reliability for a large-scale surgery [12], [50], [51]. Nonetheless, two recent meta-analysis studies, comparing PSI-based interventions to traditional surgery using invasive instruments on approximately 5000 patients, reported significant differences with regards to operative time and blood loss in favor of PSI [52], [53].…”

“…Similarly, the tibial angular error in the sagittal plane, while being lower than ±2 • , must be carefully evaluated as it may lead to prosthesis impingement issues in the knee flexion [8], [50].…”

Knee Prosthesis in the Computer Era

“…Although the history of the evolution of TKA designs is not devoid of theoretically perfect but clinically unsustainable examples [10][11][12] , research continues to advance TKA. Implant design and materials, cementation, and postoperative knee alignment have been studied extensively 13 . The advances in polyethylene technology were a real breakthrough in the evolution of TKA, which decreased the revision rates significantly but did not eliminate the need for revision completely.…”

Software Solution Integrated in Three-Dimensional Technologies for Preoperative Planning of Tibial Plateau Fractures

“…Reconstruction of tibial plateau fractures can be supported by 3D technologies [4], in order to minimize surgery [5], as both visual and printed models provide tactile feedback and in-depth information about anatomical and pathological conditions [6,7]. Threedimensional (3D) technologies allow for optimal results in reducing fractures [8], identifying the correct alignment [9], fixing with screws [10,11], reducing the duration of surgery, blood loss and radiation exposure [12], as well as and improving mechanical alignment in total knee replacement [13,14,15], which is facilitated by patient-specific implants that fit perfectly and provide unlimited geometric mobility [16]. Post mortem computed tomography can also be used to assess complex trauma to victims [17].…”