3D Printing Calcaneal Fractures: Continuously Improving our Care by Making a Complex Problem Tangible

ABSTRACT

Calcaneal fractures are amongst the most complex injuries known to man. Their intricate anatomy and extensive damage after trauma make them difficult to understand and treat. Most surgeons specialized in foot and ankle trauma agree that in most patients surgical managements yields the best result. Functional outcome is largely dependent on preventing complications and restoring anatomy. Reconstruction of height and suntalar joint congruency for example are both associated with improved outcome. Over the years insight in the complex (patho-)anatomy has increased. First by conventional radiographs, later with computed tomography. Recently 3D scans and prints have been added to this armamentarium. The study in the current issue of the Journal of Investigative Surgery explores the use of 3D printed calcaneal fractures and the effect on restoring anatomy and functional outcome. An invited short commentary was provided.

Keywords::

• calcaneus
• three-dimensional
• functional outcome
• foot ankle trauma
• surgery

This article is referred to by:

Comparison of the Conventional Surgery and the Surgery Assisted by 3d Printing Technology in the Treatment of Calcaneal Fractures

In this issue of Journal of Investigative Surgery the results of a randomized trial on the use of 3D printed calcaneal fractures are presented [1]. The 3D printed models of the fracture and mirrored image of the contra-lateral side were used to more clearly assess the deformity (plan), to simulate the procedure (practice), to pre-bend the plate and select the right sized screws (prepare), and to use these insights during the definitive surgery (perform).

The results from this study show a 22% shorter operation, with less blood loss and less use of image intensifier. At final follow-up the difference in radiographs were a 2.8° in Böhlers angle, 4° in Gissane's angle, 2 mm in calcaneal width, and 3 mm in height. All statistically significant in favor of the 3D-group. Functional outcome was measured using the AOFAS score, which showed a score of 85.5 in the 2D group and 87.6 in the 3D group. This difference was not statistically different after a minimum of 12 months follow-up (mean 14.8).

Three-dimensional imaging has been around for a while and has found a wide field of application in orthopaedic trauma surgery. Either as pre-operative planning, per-operative control of reduction and implants [2], or navigated placement of implants [3]. The next step was digital disarticulation or segmentation to remove the adjacent (talus and cuboid) bones to really visualize, even better than in vivo, the subtalar and calcaneocuboid joint [4],[5].

The addition of printing the 3D image has been available for approximately three decades. In calcaneal fractures, one of the most complex and disabling entity in osseous trauma, the technique has been described first in 1991. In this publication 2 mm CT-scan cuts were made to create a 3D model of the entire foot, compared to the 0.5 mm cuts used today and 3D printing after segmentation.

The 3D prints were initially used to gain more insight in fracture patterns to improve operative planning [6],[7]. Followed by improving communication and increase inter-observer agreement of calcaneal fracture classification [8],[9]. 3D printing after segmentation did have a positive effect on agreement compared with complete foot 3D images or digital 3D images [10],[11]. Currently, the focus is mainly on the use of 3D to prepare the operative procedure, and to improve the surgical outcome (reduction) [12]. But some have taken steps even further and have implanted a 3D printed titanium calcaneus prosthesis following resection [13].

As stated by the authors, an additional benefit of the 3D prints is that it improved patient communication, understanding, compliance and satisfaction. Which is of especial importance in the current age of informed consent, shared decision making and teach back methods. Especially in the calcaneal fracture population this might be of additional value and potentially lead to additional cost-savings in the future.

Outcome assessment following the treatment of a displaced intra-articular calcaneal fracture is usually performed using physical exam, radiographs, patient related outcome measures (PROMS), and sometimes with gait (or plantar pressure) analysis. With regards to physical exam the range of motion of the subtalar joint has been linked to improved outcome. Over 30 different PROMS have been used in calcaneal fractures, of which the AOFAS score is used most frequently. The AOFAS scores reported in the current publication in the Journal of Investigative Surgery are in the high end of functional outcome reported in the literature. It can be argumented that this score is at the maximum for patient with an operative treatment for a displaced intra-articular calcaneal fracture. Hence, the lack of difference between the two groups.

The value of radiographic measurements on 2D conventional radiographs in assessing outcome has been disputed for many years [14]. For example pre- or post-operative Böhlers angle has been linked to outcome inconsistently. Various scoring systems for post-operative CT scans have been developed. The authors however still use a 2D assessment of the overall anatomy and congruency of the subtalar joint. Future research should focus on the development of accurate 3D analysis of the post-operative results, for example 3D mapping of the subtalar joint. Secondly, these findings should be related to long-term outcome. In addition, more studies are needed to put the cost-benefit discussions to rest. Shorter operative procedures, superior reduction, and improved compliance all have cost saving implications, both at short-term follow-up and at long-term follow-up.

In conclusion, the authors are to be commended for their effort. The results look promising. Albeit the currently used outcome measures might not be sensitive enough to detect the differences at a follow-up of about 1-year. Joint arthritis or the lack thereof might develop after several years. Longer follow-up is needed to prove the indisputable fact that 3D is of absolute benefit and is here to stay.

DECLARATION OF INTEREST

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.