The Effect of Hydroxyapatite-Coated, Reinforced, Nonabsorbable Polyfilament Suture Material on Tendon-Bone Healing.

Abstract

Anterior cruciate ligament (ACL) injuries are prevalent among athletes and the general population, with ACL reconstruction (ACLR) being the standard treatment. However, effective tendon-bone healing (TBH) remains a challenge. Hydroxyapatite (HAp), widely used in orthopaedics and dentistry, has yet to be fully explored for its potential to enhance TBH. HAp-coated, reinforced, nonabsorbable suture materials can act as a bioactive and osteoinductive bridge, expediting TBH after ACLR. Controlled laboratory study. Gelatin-based solutions were used to coat suture materials with HAp, forming stable layers analyzed via scanning electron microscopy and energy-dispersive spectrum. Sixteen New Zealand rabbits underwent extra-articular TBH modeling, with the right knee as the experimental group and the left as the control. Evaluations were conducted at 6 and 12 weeks, including histomorphometry, microcomputed tomography (micro-CT) for bone formation and mineral density, and tensile testing to assess mechanical properties. Histological analysis demonstrated significantly higher bone/fibrous interzone area ratios in the experimental group at the 6th week (1.24 ± 0.14 vs 0.45 ± 0.18; <i>P</i> = .011) and 12th week (2.07 ± 0.47 vs 0.74 ± 0.11; <i>P</i> = .013). Circumferential bone formation at the 6th week was markedly greater in the experimental group (89.17% ± 5.97% vs 29.66% ± 10.05%; <i>P</i> = .012). Micro-CT showed increased bone mineral density (2.09 ± 0.41 vs 1.35 ± 0.36; <i>P</i> = .037) and reduced bone tunnel circumference at the 12th week. Biomechanical tests indicated greater stiffness (4.22 ± 1.33 vs 3.18 ± 0.76; <i>P</i> = .044), with no significant differences in failure load or displacement at the 12th week. HAp-coated sutures significantly improved TBH (particularly histological results at the 6th week), enhancing bone integration and mechanical properties in the extra-articular TBH model. The use of HAp-coated nonabsorbable polyfilament sutures may enhance TBH. Early histological evaluations indicated a positive effect on TBH, which was further corroborated by radiological and biomechanical improvements. These findings warrant further clinical investigation to explore potential applications.