Current concepts in total knee arthroplasty: Patient specific instrumentation

Single-use, patient-specific instrumentation technology in knee arthroplasty: a comparative study between standard instrumentation and PSI efficiency system

Patient-specific instrumentation is a surgical technique that was created to improve the accuracy of implantation, surgical time and workflow in total knee arthroplasty. This study is a single-center, single-surgeon randomized clinical trial. The aim of this work was to evaluate clinical efficacy of PSI versus standard surgical instrumentation in malalignment risk and blood loss reduction. From April 2015 to September 2016, 40 patients for a total of 40 knees were included in the randomization process. Each patient underwent CT scan of the lower limb including hip, knee and ankle joint with the realization of the PSI system and the TKA with Medacta GMK Primary^®. Patients were evaluated 1 month after surgery with X-ray and after 2 months with clinical examination and assessment by Knee Society Score (KSS). Blood loss was detected by adding the values calculated in the operative room and the blood loss in the vacuum systems. In the study group, mean value of KSS was 85.2 (IC 95% 81.2-88.5), mean blood loss was 657 ml (IC 95% 580.6-735.4), and mean value of femorotibial angle was 178.8° (IC 95% 178.5-179.3). In the control group, mean value of KSS was 87.2 (IC 95% 85.3-89.4), mean blood loss was 866.5 ml (IC 95% 763.3-972.5), and mean value of femorotibial angle was 178.9°(IC 95% 177.6-180.3). The Student t test detected a significant difference in blood loss between groups (p < 0.05), and no differences were found between KSS. The single-use instrumentation should improve precision, operative time, turnover time, sterilization and maintenance costs and could help to reduce infection risks. Our results confirm only the improvement on reducing blood loss. In our opinion, this technique should be used in selected patients when the surgeon could have some difficulties to perform femoral cuts on coronal plane or when patients need to have a very little blood loss due to other conditions.

Hospital-based Patient-specific Templates for Total Knee Arthroplasty: A Proof of Concept Clinical Study

Introduction:

All available patient-specific instruments or patient-specific templates (PSTs) are controlled by implant companies. Most of these companies outsource some of the steps of the PST such as imaging, preoperative planning, manufacturing of PST, and packing/sterilization. This is a proof of concept clinical study on the hospital-based PST system for total knee arthroplasty (TKA).

Methods:

A total number of 257 TKA procedures were performed on the basis of a new concept of hospital-based PSTs. All 5 steps of the PST [ie, imaging (computed tomographic scanning), planning, PST production, packing/sterilization, and surgery] were performed by the hospital. All cases included in this work are documented in the Egyptian Community Arthroplasty Register.

Results:

All cases had their surgeries performed without resorting to conventional intramedullary guides. Computed tomography–based imaging was easy and affordable. Planning was controlled by the surgeon. Polyamide nylon was the best available material and it was autoclavable. Desktop 3-dimensional printers were able to produce PSTs made of nylon, but it was difficult and time consuming. Industrial printers were superior in quality to desktop printers but more expensive. The whole process could be performed in as short a duration as 3 working days.

Conclusions:

Hospital-based PST was feasible and it was facilitated by the introduction of desktop 3-dimensional printers. This technique was less expensive and more time saving than commercially available PSTs as well as the conventional TKA.

Computer-Assisted Orthopedic Surgery: Current State and Future Perspective

Introduced about two decades ago, computer-assisted orthopedic surgery (CAOS) has emerged as a new and independent area, due to the importance of treatment of musculoskeletal diseases in orthopedics and traumatology, increasing availability of different imaging modalities, and advances in analytics and navigation tools. The aim of this paper is to present the basic elements of CAOS devices and to review state-of-the-art examples of different imaging modalities used to create the virtual representations, of different position tracking devices for navigation systems, of different surgical robots, of different methods for registration and referencing, and of CAOS modules that have been realized for different surgical procedures. Future perspectives will also be outlined.