Mechanical augmentation of rotator cuff repair using magnesium pins

• Main Author: Foo, Yong Li
• Other Authors: Chou Siaw Meng
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/167440
• Institution: Nanyang Technological University

An injury known as rotator cuff tear can be caused by various activities. To repair this injury, there are different techniques available, including mesh augmentation repair, suture anchor repair techniques, and superior capsular reconstruction. However, due to the limitations of each technique, it is common for re-tear of the rotator cuff to occur after surgery. Therefore, there is a need to study and improve repair techniques. The objective of this study is to evaluate the behaviour of mechanical augmentation of rotator cuff repair using magnesium pins. Eight sheep shoulder specimens with a full thickness tear of the infraspinatus tendon were repaired, two by double-row repair and six using the modified Mason-Allen repair technique. Double row repair was initially selected as it is an accepted standard of care in shoulder surgery. However, with the double row repair configuration, the specimens failed at the on set of the experiment, preventing any data collection. Thus the remaining six specimens were repaired with the modified Mason Allen repair technique. Three out of six of these repaired specimens were additionally treated with magnesium pins. The specimens were then subjected to cyclic load testing between 10 N and 180 N for 3000 cycles, with gap formation recorded every 500 cycles. An ultimate failure load test was also conducted on each specimen at a rate of 1 mm/s. Results indicated that the specimens with magnesium pins had a mean gap formation of 20.34 ± 1.10 mm, while those without magnesium pins had a mean gap formation of 15.26 ± 0.90 mm. In addition, the mean ultimate failure load for specimens with magnesium pins was 329.90 ± 9.80 N, and for those without magnesium pins, it was 405.89 ± 23.93 N. The mode of failure for all specimens was infraspinatus muscle failure, except for one specimen which failed due to suture pull through tendon. The study concluded that the use of magnesium pins with suture alone is not suitable for rotator cuff repair due to significant gap formation. This could lead to the tendon pulling through the pins and potentially result in further damage to the tendons.