Corrective Four-fold Osteotomy of The Forearm Performed with 3D-Planning and Patient-Specific Guides

Preoperative three-dimensional planning methods for the use of patient specific implants have been extensively described ...


Introduction
Malunion following a distal forearm fracture, especially the radius, is a common complication that may treated by corrective osteotomy surgery [1][2][3]. Accurate reconstruction is essential as a statistically significant relationship has been found between mal-positioning and clinical outcome [4,5]. Additionally, it has been demonstrated that standard anatomical plates may lead to considerable positioning errors in individual patients [6]. Threedimensional (3D) planned patient-specific guides and implants are increasingly valuable, allowing for precise corrective osteotomies of complex multiplanar forearm deformities [7,8]. In this report, we describe the management of a severely malunited forearm fracture previously inadequately treated via corrective osteotomy. In this case, a novel patient-specific plate, which fits the bone geometry and accurately was used to restore bone alignment.

Case Report
The 25-year-old female patient presented in our outpatient clinic with left-sided dominant forearm malunion following radius and ulna shaft fracture at 14 years of age. The fracture was treated without initial reposition in a splint cast. Therefore, the patient developed a pronounced reduction in pro-and supination despite intensive occupational therapy. Five years post-traumatically, corrective osteotomy of the forearm was performed in an external clinic in order to improve range of motion. In the surgical report intraoperative adjustment of the preoperative planning was necessary to ameliorate supination of the forearm. Following surgery increasingly limited pronation was denoted and the patient developed shoulder pain secondary to the fixed forearm malposition.
On initial presentation clinical and radiological ( Figure 1) examination showed a pronounced deformity of the forearm with reduced pro-and supination of 0-20-70°. In comparison range of motion was 75-0-85° for the right side. The wrist flexion and extension, radial and ulnar deviation, as well as elbow flexion and extension were symmetric and in the normal range of motion. Grip strength measured by Jamar was 20% less compared to the opposite side.
In the clinical examination a slight laxity of the distal ulno-radial joint (DRUJ) was to the contralateral right side, with additional pronounced but painless crepitation during passive mobilization. The peripheral sensomotoric inspection was unremarkable.

Surgical Procedure
The Henry approach for the radius shaft was utilized through the interval of the brachioradial and flexor carpi radialis tendon.
Primary inspection revealed the severe deformation of the radius with a ventral displacement of the supinator muscle. The resulting bumps and ridges of the radius were used for the exact fit of the guides. The supinator muscle was subsequently completely released until its insertion at the radial head; the pronator muscle could be preserved in its entirety. The large drill and saw guide, which included both osteotomies to the radius, was then placed in position. The guide was conceptualized with a gap to enable the pronator muscle to be preserved. Two K-wires of 2.0mm thickness were then each placed in the middle and proximal fragment ( Figure   5). Subsequently the osteotomies were performed as a single-cut osteotomy. The K-wires and guide were then removed, and the K-wires were once again inserted in the previously drilled holes.
Using the wires, the middle strongly pronated fragment was supinated until all K-wires were aligned. Next, the reposition guide was placed over all wires and fragment approximation to the guide was achieved using a reposition pincer. The tentative reposition was according the pre-operative plan. Subsequently, a 10-hole Now, a second incision over the previous scar was performed in order to access the distal third ulnar shaft from dorsal. Once again, the interval between the extensor carpi ulnaris and flexor carpi ulnaris musculature was used. However, due to extensive adhesion the former needed to be released. The extensively deformed ulnar shaft with an angulation of almost 40° was exposed and the corresponding drill and saw guides were placed in position. The planned two K-wires were then inserted in the distal and proximal fragment. This was followed by a z-like single-cut-osteotomy, with the middle osteotomy plane corresponding to the single-cut plane.
The guides were subsequently removed and the tapered ends of the osteotomy completed with the saw.
Then the derotation into anatomical position was performed and a short plate for ulna shortening osteotomy was placed over the four K-wires, followed by the reposition guide.

Follow-up
For eight weeks following surgery no weight bearing was permitted, but active mobilization was permitted through an

Discussion
Computer-assisted 3D planning is an increasingly utilized method permitting exact quantification of the malunion and generation of patient specific guides. Whilst translation of the preoperative 3D data to correct a malunion can be challenging, comparative studies with conventional osteotomies have demonstrated favorable results regarding accuracy, surgery time and functional outcome [6,9]. The complexity of the osteotomies may vary strongly, ranging from single-cut osteotomies to multiple, composite osteotomies, in which additional rotation of fragments is used for correct anatomical positioning [10]. Particularly the preoperative estimation and intraoperative correction of a rotation has been proven more reliable compared with image intensifiercontrolled techniques. Thus, this technique particularly lends itself to the treatment of complex correction [11]. Disadvantages of this technique includes the need for specialized software, planning time, including guide design, and costs for the custom-made template and CT scan [9]. Nonetheless, considering the current advances in 3D printing technology patient specific custom-made guides present an effective treatment method for complex multiplanar and rotational malunions of the forearm.

Conflict of Interest
Co-founder of former CARD AG (Andreas Schweizer).