Patient specific instrumentation in total knee arthroplasty: a state of the art

Abstract

Patient specific instrumentation (PSI) is a modern technique in total knee arthroplasty (TKA) aiming to facilitate the implant of the prosthesis. The customized cutting blocks of the PSI are generated from pre-operative three-dimensional model, using computed tomography (CT) or magnetic resonance imaging (MRI). A correct surgical plan is mandatory for a good surgical implant. The PSI guide takes into account any slight deformities or osteophytes and applies preoperative planning for bone resection, using the pre-determined implant size, position, and rotation. The apparent benefits of this technology are that neutral postoperative alignment is more reproducible, surgical time is decreased, and the entire procedure results more efficient and cost-effective. The use of PSI is indicated when advanced osteoarthritis, severe pain, and limited function/walking ability are present, such as in a standard instrumentation TKA. In addition to that, PSI finds its indication when intra-medullary guides cannot be used. For example, when there is a post-traumatic femoral deformity. Large debates have taken place about this topic during the last years and, at the moment, there is no consensus in literature regarding the accuracy and reliability of PSI as many studies have shown controversial and inconsistent results. Literature does not suggest PSI techniques as a gold standard in TKA, and therefore it cannot be recommended as a standard technique in standard, not complicated primary TKA. Moreover, literature does not underline any improvement in components alignment, surgical time, blood loss or functional outcomes. Nevertheless, many patients who underwent TKA suffered a previous trauma. In case of deformities, like femoral or tibial fractures healed with a malalignment, preoperative planning may result difficult, and some intra-operative technical difficulties can occur, such as the use of intra-medullar rod. In these selected cases, PSIs may be very useful to avoid errors in alignment and planning.

2D/3D reconstruction of the distal femur using statistical shape models addressing personalized surgical instruments in knee arthroplasty: A feasibility analysis

“…We have, however, to remark 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 . While PSI cannot be regarded as the gold standard in total knee replacement, advanced osteoarthritis conditions can be surgically addressed through such a technique, especially in conditions of bone deformity, which can prevent the use of intra‐medullar bars …”

“…The PSI technique, accepted for advanced osteoarthritis, severe discomfort, and reduced function/walking capability, spares the intramedullary canals, exploited instead with the conventional instruments, and does not require invasive intra‐osseous pins, which are mandatory in the navigated surgery . While questioning cost‐effectiveness, different studies described the advantages of PSI surgery as a more reproducible neutral postoperative alignment and decreased surgical time, with no further intra‐operative complications . Despite the benefit of being less invasive, the use of PSI requires the availability of the digital bony surfaces, which are obtained from pre‐operative computed tomography (CT) or magnetic resonance imaging (MRI), the identification of anatomical landmarks to allow the planning and design of the personalized resection instruments .…”

3d Printing Technique for Patient-Specific Instrumentation in Total Knee Arthroplasty

“…Инновационным решением этой проблемы является применение прецизионных персони-фицированных направителей (ппН), которые позволяют точно выполнять реконструкцию оси нижней конечности, сокращать время опе-ративного вмешательства, улучшать клини-ческие результаты, точно определять необхо-димую ротацию компонентов эндопротеза по сравнению с компьютерной навигацией и стан-дартными направителями [9][10][11][12][13][14][15]. Имеющиеся методики эндопротезирования коленного сус-тава с использованием ппН включают в себя применение индивидуальных резекционных блоков, создаваемых методом компьютерного моделирования с последующим изготовлением на 3D-принтере.…”

Ultrasound imaging and segmentation of bone surfaces: A review

“…Due to the superior bone imaging quality, CT is the preferred pre-operative modality used for planning the intervention 11,12 . However, MRI has also emerged as pre-operative imaging alternative specifically for procedures where CT is not necessarily required such as femoroacetabular impingement surgeries 13,14 or total knee arthoplasty using patient specific instrumentation 15,16 . The main drawbacks of MRI and CT in CAOS are the cost of imaging, radiation exposure from CT and mostly being performed pre-operatively for planning the intervention.…”