Computer-assisted preoperative planning: the future is now! Commentary on an article by Joseph P. Iannotti, MD, PhD, et al.: "three-dimensional imaging and templating improve glenoid implant positioning".

Abstract

Commentary Iannotti et al. present a very interesting and useful investigation into the use of three-dimensional preoperative imaging and templating to assist in planning the positioning of the glenoid component during anatomic shoulder arthroplasty. Additionally, any possible benefit of patient-specific instrumentation was evaluated. To my knowledge, this is the first investigation into the clinical efficacy of this particular emerging technology. All too often, new technological innovations are rapidly adopted without any proven efficacy. This study provides evidence of the role of three-dimensional imaging and templating in the surgical treatment of patients with primary osteoarthritis. This article provides a glimpse into the near future of anatomic shoulder arthroplasty. The Materials and Methods portion of this article was appropriate to achieve the goals of the study. The study consisted of a prospective, randomized controlled trial involving a comparison of patients undergoing three-dimensional imaging and templating with patients undergoing the same imaging and templating technique with the addition of patient-specific instrumentation to assist in glenoid component positioning; a third cohort of patients who had undergone conventional two-dimensional templating was used to serve as a historical control. The retrospective latter part of this study slightly weakens its experimental design. However, given that all of the surgical procedures were performed by experienced surgeons well into their learning curve, I doubt that prospectively collecting the data on the two-dimensional group would have appreciably impacted the results. It is unclear why the authors included twenty-five patients in one group, twenty-one patients in another group, and seventeen patients in the third group. Because no patient was lost to follow-up or withdrew from the study, a better explanation of the choice of the number of the subjects to be included in each group seems warranted. This investigation was limited to a computed tomographic evaluation of glenoid component positioning at a short-term follow-up (less than three weeks). No clinical data are provided, nor would they have been useful that early in the postoperative period. The Results portion of this article yields two very important points. First, three-dimensional imaging and templating are superior to conventional two-dimensional planning in achieving the desired placement of the glenoid component in anatomic shoulder arthroplasty for primary osteoarthritis. Second, the addition of patient-specific instrumentation did not appreciably improve the surgeon’s ability to place the glenoid component in the desired location. Unfortunately, because the follow-up was too short for any meaningful clinical data to be provided, the ultimate clinical implications of this improvement in glenoid component positioning with use of three-dimensional imaging and templating compared with two-dimensional imaging and templating remains unknown. Glenoid component loosening remains a pervasive factor in the failure of anatomic shoulder arthroplasty1. Although many factors undoubtedly contribute to glenoid component failure, proper positioning of the glenoid component would seem to be critical in avoiding this complication. Iannotti et al. have shown a reproducible and accurate method to place the glenoid component in the desired position with use of three-dimensional imaging and templating and have further demonstrated the superiority of this technique over conventional two-dimensional preoperative planning. The methods of glenoid positioning used in this study would seemingly prove useful in nearly all cases of anatomic total shoulder arthroplasty. The value of this method would likely prove more beneficial in difficult cases involving substantial glenoid wear. Another potential area of applicability for the three-dimensional preoperative planning shown in this study that was not discussed by the authors is the use of this technique to preserve existing glenoid bone. Walch et al. recently demonstrated the importance of preservation of subchondral bone in preventing glenoid component failure2. Using information gained from three-dimensional imaging and templating described by Iannotti et al., the radius of curvature of the native glenoid could be established to allow the use of instrumentation and implants that do not require removal of subchondral bone to permit component placement. Importantly, this investigation did not show the benefit in using patient-specific instrumentation. In the increasingly cost-conscious environment of health care, higher cost must yield substantial benefit. The main limitation of this study was the lack of clinical correlation with the radiographic results. Although the three-dimensional preoperative planning proved to be better than two-dimensional preoperative planning at achieving the desired glenoid component positioning, the clinical relevance of this is unclear. I would encourage the authors to continue to follow these patients and to correlate clinical outcomes, complications, and revision rates with glenoid component positioning. If a relationship is subsequently demonstrated, more value will be added to this technique. Congratulations to Dr. Iannotti and his associates for their work on this study. This article shows that the future is now in using novel technology to improve our radiographic results. Time will tell if these radiographic improvements will translate into better clinical results, lower complication rates, and improved prosthetic longevity for our patients.