gms | German Medical Science

Objectives: Posttraumatic bone deformity may lead to reduced range of motion, joint instability and pain justifying corrective osteotomies to restore normal anatomy and function as close as possible. We present our experience with a 3D planning tool and 3D printed patient specific bone surface contact drilling and sawing guides used for corrective osteotomies of the forearm bones.

Method: From 2008 to 12.2015 118 osteotomies in 83 (41 male, mean age 37y, 9-66y, SD 17y) patients at the forearm have been performed (26 radius shaft, 17 ulna shaft, 29 distal radius extraarticular, 30 intra and combined intra and extraarticular distal radius). Follow up time was in average 2.1y (0.5 - 7.7y, SD 1.3y). All patients had preoperative CT scans of the malunited and the contralateral bone. Segmentation was performed with Mimics software (Materialise). Analysis of malposition and OP planning was performed with an in-house developed software (CASPA, card.balgrist.ch). The program allows standard CAD functions including automatic volumetric fitting (overlay of mirrored bone areas on malunited bone), quantification of malposition, calculation of screw axis / single plane cut and the complete construction of individualized bone surface contact drilling and sawing guides (3d printed by Medacta).

Results: Except 4 (3.4%), all osteotomies consolidated. All 4 had an implant fracture, one after 3 weeks from a scooter accident, 1 patient after 6 months at the ulna shaft and 2 after 4 and 6 months at the distal radius. All were reoperated and consolidated thereafter. Almost all patients improved function and pain particular secondary instability of the DRUJ disappeard always. In 5 patients pain did not improve, one needed partial wrist fusion. One patient had severe neuralgic pain of the N.cut antebrachii lat. after plate removal. The residual error of the osteotomy was calculated from the 2 months post op CT scan and is between 1-2° (rotational) and 1-2mm (translational) for the radius and ulna shaft and 3-5° and 1-2mm for distal radius. Intraartricular fragments were corrected to a residual error of 2-6° and steps were decreased to 0-0.6mmThere was no infection so far.

Conclusion: The technology can improve precision by enabling the surgeon to quantify deformities and to simulate the intervention preoperatively in 3D. The short time promising results concerning accuracy and feasibility of complex intraarticular cases justifies the preoperative extra expense of time and effort.