Malunion is the most common complication following a distal radius fracture.
Restoration of anatomy is a key factor in obtaining good functional outcome, but this can be technically challenging.
Next to radiographs and CT-scans, three-dimensional (3D) visualization and printed bone models can further improve understanding of the malunion pattern.
The use of three-dimensional (3D) computer planning and the production of patient-specific instruments allow accurate and reproducible correction, especially in complex malunion patterns.
The additional cost is one of the major disadvantages of the 3D technique.
Further clinical investigations are necessary to better define the added value, the indications, and cost-effectiveness of 3D technology in the treatment of malunions.
A 48-year old woman sustained a severely displaced intra- and extra-articular fracture of the left distal radius. She was initially treated at another facility with closed reduction, additional external fixation, and K-wires.
She presented 8 months later, with an intra- and extra-articular malunion, causing persistent wrist pain (VAS 8/10) and severe functional impairment (Quick-DASH 62).
Physical examination revealed residual pain at the radiocarpal and distal radioulnar joint, restricted wrist movement, and decreased grip strength. The Modified Mayo Wrist score was poor (MMWS 10).
Can 3D technology provide a more accurate reduction and better outcome of her complex distal radius malunion ( Fig. 1 )?
Importance of the Problem
Malunion of the distal radius is a common complication, with a reported incidence of up to 23% of nonsurgically treated distal radius fractures. It often causes persistent wrist pain and functional impairment. Additionally, secondary carpal malalignment and intraarticular deformities can lead to early degenerative changes.
When surgical treatment is deemed necessary, a corrective osteotomy is the procedure of choice, and clinical studies have shown a significant correlation between the precise reconstruction of normal anatomy and the clinical outcome.
Planning and performing a corrective osteotomy can be a technically challenging procedure. Conventional two-dimensional radiographs are limited in the visualization of complex intraarticular or rotational deformities of the malunited wrist. And studies have shown that even following careful planning, restoration of bony alignment was only obtained in 40% of patients. A complication rate of up to 42% has been reported following corrective osteotomy, with tendon injuries and delayed or nonunion being the most commonly reported problems.
Three-dimensional technology might address some of these problems, and improve outcome following corrective surgery ( Box 1 ).
Step 1 DICOM (Digital Imaging and Communications in Medicine) data are collected through computed tomography (CT) scans of the malunited and the contralateral forearm. This can be done simultaneously with the patient in the prone position, shoulders in full extension and both arms overhead, to decrease radiation exposure. To allow precise 3D reconstruction of bony anatomy, a specific scanning protocol needs to be followed with scanning parameters set at a tube current of 10–30 mA and voltage of 90–120 kV, a slice thickness of < 0.625 mm and a field of view of 200 mm × 200 mm or smaller.
Step 2 Virtual 3D models (STL files) are created, using dedicated medical image processing software. Precise assessment of the deformity in all planes is now possible and corrective surgery can be planned in detail, based on the healthy contralateral side.
Step 3 3D technology will allow this virtual plan to be translated to the operation room, and multiple methods have been developed to do this: virtual and three-dimensional printed bone models, optical tracking devices, synthetic or bony prefabricated wedges that fit into the osteotomy gap, and the use of patient-specific surgical cutting and drilling guides. The last one appears to be the most promising technique. The drilling and cutting guides are designed based on the surgical plan, and 3D printed in medical-grade material that can be sterilized.
What is the added value of three-dimensional (3D) planning and surgical guidance compared to more conventional techniques in the correction of distal radius malunions?
Most surgeons are confident that preoperative planning with two-dimensional (2D) imaging for corrective osteotomy of distal radius malunions leads to acceptable results and complication rates in the majority of cases. They argue that 3D technology complicates the procedure without proven added value or cost effectiveness.
Finding the Evidence
Cochrane library: Distal radius malunion
Pubmed (Medline): ((Colles’ fracture* [tiab] OR distal radius fracture* [tiab]) AND (Three-dimensional [tiab] OR 3D [tiab] OR 3-D [tiab] OR computer assisted [tiab] OR computer simulated [tiab] OR computer aided [tiab] OR virtual planning) AND (Malunited fracture* [tiab] OR malunion [tiab] OR osteotomy [tiab] OR corrective osteotomy [tiab]))
Randomized controlled trials (RCTs), systematic reviews, case series, and case reports published between January 1, 2000, and January 20, 2020 were considered
Review of references of eligible studies
Articles that were not in English, French, German or Dutch were excluded
Quality of the Evidence
Randomized controlled trial: 1
Clinical application review: 1
Systematic review of case series and metaanalysis: 1
Case series: 17
Case reports: 6
Evidence From Level I Studies
Buijze et al. included 40 patients in a randomized controlled trial to compare conventional 2D planning with 3D computer-assisted planned corrective osteotomies for extra-articular distal radius malunion. They found a significantly improved radiographic outcome (radial tilt and volar angulation) ( P < .05), and a trend toward better PROMs (DASH and PRWE) in favor of the 3D planning group, which did not attain significance because of (post hoc) insufficient power of the study. However, there were no significant differences in pain, satisfaction, range of motion, and grip strength.
Evidence From Level IV Studies
In a systematic review including 15 studies and 68 patients treated with 3D virtual planning for both extra- and intraarticular malunions, de Muinck Keizer et al. found a statistically significant improvement ( P < .05) of the radiographic parameters in 96% of the patients, in whom anatomy was restored to within 5 degrees (angulation) or 2 mm (ulnar variance) of their normal values. This is clearly better than the 40% achieved with meticulous two-dimensional preoperative planning, using the same criteria for restoration of anatomy. Furthermore, a significant ( P < .05) improvement of wrist range of motion and grip strength was noted, with an overall complication rate of 16%, compared to a reported complication rate of up to 42% with conventional techniques.. Three more recent case series on three-dimensional corrective osteotomies of the distal radius showed comparable results, reinforcing the growing evidence in support of three-dimensional technology.
The use of three-dimensional technology and patient-specific guides allows precise reconstruction of intraarticular step-offs, and seems to be of most benefit for complex deformities of the distal radius.
Besides this growing evidence for better clinical and radiographic results, three-dimensional technology allows for a reproducible and safe correction of distal radius malunion and reduces operation time, blood loss volume, and radiation exposure during surgery. The reported complication rates following 3D-assisted osteotomies of the distal radius compare favorably to those following conventional techniques.
The disadvantages of 3D technology are the need for specialized computer software, radiation exposure during CT-scanning, the time and effort for preoperative planning and the additional cost of the custom-made surgical guides and implants. These existing costs currently prevent everyday clinical use. To address some of these issues, Caiti et al. have proposed a software solution to streamline the design of patient-specific instruments to make 3D technology more accessible.
Evidence From Level V studies
Other authors have suggested that in-hospital planning and 3D printing of guides can decrease the cost of 3D technology.
Although the added value and cost-effectiveness of three-dimensional technology need to be confirmed, three-dimensional planning and surgical guidance facilitate restoration of normal anatomy. It allows accurate, reproducible, and safe correction of the malunited radius. Especially complex deformities: multidirectional mal-alignment and intraarticular deformations of the distal radius will benefit from the use of three-dimensional techniques. Further clinical investigations are necessary to find the correct indications to use this technology and determine its cost-efficiency. New technical developments, including lower-dose scanning technology, software improvements, artificial intelligence, and in-hospital printing may lower the associated costs and improve cost efficiency.