3D Imaging and Templating May Improve Glenoid Positoning in Anatomic TSA
This study serves as an encouraging step toward improving results and longevity of anatomic total shoulder arthroplasty in patients with osteoarthritis.
Timothy G. Reish, MD
Iannotti JP, Weiner S, Rodriguez E, Subhas N, Patterson TE, Jun BJ, Ricchetti ET. Three-dimensional imaging and templating improve glenoid implant positioning. J Bone Joint Surg Am, 2015 Apr 15; 97 (8): 651-658.
In this prospective, randomized, controlled study, Ianotti et al compared glenoid implant positioning in 3 patient cohorts:
- 25 patients who underwent anatomic total shoulder arthroplasty (TSA) with 3D CT imaging and templating
- 21 patients who underwent anatomic TSA with 3D CT imaging and templating plus patient-specific instrumentation (PSI) to assist with component positioning
- 17 patients who underwent anatomic TSA with traditional 2D templating
All patients had postoperative, artifact-reduction 3D CT scans to evaluate glenoid position relative to the preoperative plan. No patients in this study were lost to follow up.
The authors found that 3D imaging is a superior to traditional 2D imaging for templating in that it yields superior glenoid implant positioning when performing anatomic total shoulder arthroplasty. The authors also concluded that the addition of PSI did not provide more accurate component positioning.
This well-done study provides strong evidence that the use of 3D imaging and templating of the glenoid in patients undergoing anatomic TSA can result in improved implant positioning, leading to improved results and, potentially, increased longevity of the glenoid component.
Anatomic TSA for osteoarthritis is a successful operation that can provide pain relief and significant gains in shoulder range of motion for a vast number of patients. Glenoid component loosening is a pitfall of this surgical procedure. It is multifactorial and remains a significant hindrance to longevity of the prosthesis. One of several factors that can contribute to the problem of aseptic glenoid loosening is component positioning.
Dr. Iannotti and colleagues should be commended for their work. They have shown 3D imaging to be a reliable method with which to template the glenoid in anatomic TSA, allowing the surgeon to more accurately place the glenoid in the face of arthritic deformity and glenoid bone loss, as well as recognize the need for augmentation or grafting in these patients.
Walch et al have shown us that patterns of bone loss need to be identified to minimize the amount of healthy, structural bone that is reamed away from the scapula in an effort to gain a concentric platform for glenoid fixation. Further, they have shown us the importance of minimizing the loss of subchondral bone to limit glenoid component failure.
Although the study by Iannotti et al is important, the clinical advantages of 3D CT and templating technique cannot yet be fully realized, as the patients in their study need to be followed longitudinally to be able to appreciate the clinical correlation between the technique and outcomes. 3D imaging and templating remains a theoretical benefit to improve glenoid positioning and reduce the incidence of loosening until longer follow-up on the clinical results of these patients can be assessed.
Regardless, this study serves as an encouraging step toward improving results and longevity of anatomic TSA for osteoarthritis.
Timothy G. Reish, MD, is a Clinical Assistant Professor, Division of Sports Medicine, Department of Orthopaedic Surgery, NYU Langone Medical Center – Hospital for Joint Diseases, New York, New York.