Customized 3D surgical guides boost accuracy of shoulder replacement surgery

A study has found that using patient-specific surgical guides improves the accuracy and stability of shoulder replacement surgery. The guides help to more accurately position the components and screws that secure the implant to the bone, thereby reducing the risk of surgical failure.

A team led by Professor Chung Seok-won of the Department of Orthopedic Surgery at Konkuk University Medical Center announced on Tuesday that they had published their research results on improving the accuracy of implant placement in joint replacement surgery in the international academic journal “Knee Surgery, Sports Traumatology, Arthroscopy (KSSTA).”

The study was conducted from 2020 to 2023 on 135 patients who underwent reverse total shoulder arthroplasty (RTSA) at four Korean university hospitals due to rotator cuff tears and other conditions. The research team analyzed the 3D structure of the patients' shoulder bones using CT scans taken before surgery, then created customized 3D-printed surgical guides (Patient-Specific Instrumentation, or PSI) and applied them during surgery.

The team compared and analyzed the surgical accuracy of 65 patients who used PSI with that of 70 patients who underwent conventional surgery. The PSI was modeled and 3D printed by the Korean company Seeann Solution.

The analysis revealed that the group using PSI achieved significantly higher accuracy than the conventional method in terms of the rotation angle (inversion angle), inclination angle, and center entry point location of the base plate attached to the shoulder bone.

The rotation angle error was 1.5 degrees vs. 6.7 degrees, the inclination angle error was 2.8 degrees vs. 5.3 degrees, and the entry point position error was 1.9 mm vs. 3.2 mm, indicating that the PSI group inserted the baseplate more precisely than the conventional surgery group.

The baseplate is a core component that forms the center of the artificial joint by fixing it to the shoulder bone (scapula), and the rounded part (ball) of the artificial joint is connected to it. If the position or angle of this component is misaligned, it can lead to unnatural joint movement or screws protruding outside the bone, resulting in surgical failure.

Screw insertion accuracy was also found to be more precise in the superior/inferior and anterior/posterior directions in the PSI group. The length of the inserted screws was also longer on average, resulting in improved fixation strength. There were nine cases of screw protrusion in the PSI group and 23 cases in the conventional group, showing a significant difference. Additionally, no cases of nerve damage or screw insertion failure were reported in the PSI group.

“This study is a multi-center comparative study encompassing various hospitals and implant systems, systematically demonstrating the effectiveness of PSI in improving insertion accuracy in shoulder arthroplasty surgery,” Professor Chung said. “It is expected to be applicable as a surgical technique for elderly patients with small shoulder bones and complex anatomical structures.”

The study results were published in the journal, Knee Surgery Sports Traumatology Arthroscopy (KSSTA), under the title “Effect of patient-specific instrumentation guidance on the accurate positioning of the baseplate and screws in reverse total shoulder arthroplasty: Multicenter comparative study” in June.