Individualendoprothetik am Kniegelenk

Abstract

This article describes the rationale and the surgical technique of patient-specific uni-, bi-, or three-compartmental knee arthroplasty using the second generation (G2) of ConforMIS™ technology. The patient-individual implants and instruments are designed and fabricated based on data from a preoperative computed tomography of the lower limb. The disposable patient-specific drill guides and cutting-jigs are manufactured under consideration of the anatomical and biomechanical axes of the knee joint and mediate efficient pre-navigation of the saw-cuts on the femoral and tibial bone without the need for an additional navigation or balancing device. The surgical technique for all types of knee resurfacement comprises the steps of cartilage removal, knee balancing in extension and flexion, sparing bony cuts, final preparation of femur and tibia, trialling, cementing of components and final choice of tibial insert. The use of individualized three-dimensional image-derived resurfacing implants, as well as personalized single-use instrumentation, facilitates the surgeon to perform an almost anatomical knee resurfacement that has the potential to restore almost normal knee kinematics. The limited data on this novel technology is promising, however long-term clinical data is needed for final evaluation of this technology.

Patient satisfaction - A comparison between patient-specific implants and conventional total knee arthroplasty

“…The PSI with reduction of bone loss faces these considerations. 9,10,14 The studies' setting does not allow any conclusion in differences of age between the types of prosthesis. Nevertheless, it seems to be more likely that patients with younger age are informed about alternatives and demanded the PSI actively.…”

Evaluation of implant fit and frontal plane alignment after bi-compartmental knee arthroplasty using patient-specific instruments and implants

“…The accuracy of femoral component positioning in this patient-specific BKA system has also been confirmed by the conformity of the measured extent of posterior femoral condyle resection with the preoperative iView plan. Furthermore, the anatomic femoral design is intended to avoid edge-loading and, in combination with the restoration of the individual tibial slope, can result in the restoration of the physiologic patient-specific knee kinematics [ 10 , 12 ]. Similar levels of accuracy were seen when a patient-specific UKA system was used in medial knee OA [ 14 – 16 ].…”

“…Preoperative computed tomography of the affected leg was performed by scanning the knee, the femoral head and talus center according to a standard protocol ( http://www.conformis.com/healthcare-professionals/imaging-professionals ) as described previously [ 10 – 12 ]. The patient-specific BKA system (which is available for resurfacing of the anteromedial as well as the anterolateral compartment) is designed using a software algorithm (iFit Technology) that registers the articular surfaces of the knee, the areas of disease and osteophyte formation, correction of any malalignment, and generates a BKA design that precisely matches the patient’s anatomy.…”

“…Primary factors for revision are pain, malalignment or instability, which is attributed to the technical complexity and insufficient fit of the implant to the patients’ individual anatomy [ 9 ]. To overcome these limitations, a patient-specific BKA system (iDuo; ConforMIS Inc.) has been introduced utilizing custom made individual instruments and implants, that are fabricated to match patient anatomy on the basis of computed tomography (CT) scans using computer-aided design and manufacturing (CAD/CAM) technologies [ 10 – 12 ]. This technology has already been introduced into the clinic for UKA [ 13 ], providing excellent radiological [ 14 ] and initial clinical outcomes [ 15 , 16 ].…”

“…This technology has already been introduced into the clinic for UKA [ 13 ], providing excellent radiological [ 14 ] and initial clinical outcomes [ 15 , 16 ]. The patient-specific BKA is designed with a bone-sparing technique that covers the cortical bone of the diseased distal femur and trochlea while preserving the cruciate ligaments as well as the intact tibio-femoral compartment [ 10 – 12 ].…”