[Patient-specific cutting guides in corrective osteotomy near to the knee joint].

Objective: Patient-specific cutting guides (PSCG) are used in osteotomy near to the knee joint to simplify the operative technique, shorten the duration of surgery, reduce radiation exposure and to exactly realize the preoperative planning during surgery, especially when complex deformities are corrected simultaneously in multiple planes.

Indications: The application of PSCG is in principle possible in all osteotomies near to the knee joint but is especially useful in multidimensional, complex osteotomy.

Contraindications: No specific contraindications.

Surgical Technique: After multidimensional 3D analysis and planning using a preoperative computed tomography (CT) protocol, a 3D-printed patient-specific cutting guide is produced. This PSCG is used during standard osteotomy near to the knee. Using this PSCG the guided sawcut and predrilling of the screw positions inside the bone for the screws of the planned angle stable osteotomy plate are performed. The amount of the deformity correction needed is "stored" in the PSCG and is converted to the bony geometry during placement of the screws in the predrilled holes through the plate after opening or closing the osteotomy. Apart from that, the surgical approach and technique are equivalent to the standard osteotomy types near to the knee.

Postoperative Management: The application of PSCG in osteotomy near to the knee does not change the postoperative management of the specific osteotomy.

Results: The use of patient-specific cutting guides leads to a higher accuracy in the implementation of the preoperative planning and the desired target axis is achieved with greater accuracy. Multidimensional complex corrections can also be exactly planned and implemented. In addition, the intraoperative radiation exposure for the operation team can possibly be reduced.