Description
[Objectives] Recently, bioabsorbable interference screws (BIS) have been developed for bone-patellar tendon-bone graft fixation in anterior cruciate ligament (ACL) reconstruction. The degree of degradation and osteoconductivity of these BIS varied, because structures and
materials of these BIS were different. Moreover, there were several adverse effects associated with some BIS have been reported. A newly developed BIOSURE REGENESORB®︎(BR) (smith & nephew) with an open architecture design, allowing bone into the screw lumen, has some advantages, especially in its osteoconductivity. Therefore, in this study, the osteoconductivity and degradation of BR were investigated 1-year after primary ACL reconstruction. In addition to that, adverse effects caused by BR were evaluated.
[Methods] From November 2021 to September 2022, 15 patients (7 males and 8 females, mean age 20.2±8.8 years old) underwent primary anatomic rectangular tunnel ACL reconstruction using BR for graft fixation on the femoral side with CT examination at 1-week and 1-year post-operation. First, on the most medial (PM), lateral (PL) or central (PC) plane of BR perpendicular to the long axis of the femoral tunnel, the maximum CT value of BR on each plane were measured. Then, the changes of the maximum CT value from 1-week to 1-year post-operation on each plane was defined as the degradation of BR. Secondly, the CT values at the center point of the screw lumen on PM, PC, and PL were measured. Statistical analysis was performed using t-tests for all parameters.
[Results] The maximum CT values of BR at 1-week and 1-year post-operation on PM, PC, and PL were 829.6±86.5 and 552.8±125.0, 880.2±76.4 and 624.9±114.4, and 885.9±77.8 and 540.7±106.6HU, respectively. There were no differences between the maximum CT values on each plane. However, the maximum CT values of BR on the planes were significantly decreased from 1-week to 1-year post-operation (PM: p<0.01 PC: p<0.01, PL: p<0.01). The CT values at the center point of the screw lumen on PM, PC, and PL at 1-week and 1-year post-operation were 70.1±44.0 and 126.1±78.5, 56.0±51.7 and 284.1±287.4, and 63.6±29.0 and 224.6±269.2HU, respectively. The CT values of screw lumen on each plane increased and there were significant differences on all planes except PM, from 1- week to 1-year post-operation (PM: p=0.06, PC: p=0.03, PL: p<0.01).
No adverse effect such as knee instability, limit of range of motion, bone cystic changes, screw breakage, or plug migration was observed at 1 year postoperatively.
[Conclusion] The CT values of the BR were significantly decreasing from 1-week to 1-year post-operation, while the CT values of screw lumen were significantly increasing. Both CT values were gradually approaching to the CT value of normal cancellous bone without adverse effects, suggesting that BR is safe and secure implants for ACL reconstruction. However, bone formation of screw lumen on medial side was poor and thus the length or placement of BR should be carefully considered.
