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In order to observe the remodeling process of the inter-strand of the four-strand graft used for anterior cruciate ligament (ACL) reconstruction, and to find the histological and biomechanical influences on this process by braiding the four-strand graft, we conducted this study in a rabbit model. The rabbit's ACLs were reconstructed with bilateral four-strand semitendinous tendons which are in parallel or braided shape. The specimens of the two groups were collected at 3, 6, 12, 26 and 52 weeks after the operation. Gross and histological observations were done and the biomechanical properties of the specimens of the 26 and 52 weeks were compared. The result showed that in regular group, at 3 weeks, the strands which were in necrosis status were still separated with each other. At 6 weeks, the grafts were enveloped with hyperplastic synovium, some outer part of the gaps between strands were filled with synovium and fused together, while the inner parts were still separated. At 12 weeks, the graft was still in remodeling progress, but the remodeling degrees of each strand were different. Some strands had fused but some were still separated with "big" interval. At 26 and 52 weeks, some inter-strand gaps were hard to discriminate, some strands were connected with connective tissue and some separated ones still showed up. The braided ones manifested a similar but more synchronized remodeling process and showed a higher inter-strands fusing rate. The biomechanical test showed that the strength of the reconstructed ACL of the regular unbraided tendons was 36% of the contralateral normal ACL, while the braided ones reached 67%. The graft strengths of the specimen of the 26 and 52 weeks in the braided graft group were significantly higher than that of the unbraided group, while the stiffness of the 52-week specimen of the braided group was significantly higher than that of the unbraided group also. From this study, we concluded that as a graft for reconstruction of the ACL, the four-strand hamstring tendon needs to pass through the necrosis, revascularization, and ligamentation progress, but different strands were not in a synchronous process. The inter-strand gap may be completely fused, partial fused, fused but connected with connective tissue or still separated. By braiding the strands, the fusing percentage of the graft could be elevated and the biomechanical properties could be improved. [ABSTRACT FROM AUTHOR]

This study evaluated the MRI signal characteristics and MRI diagnostic accuracy in identifying completely healed menisci repaired with bioabsorbable arrows. A total of 34 patients (38 menisci), with a mean age of 26.0 years, underwent arthroscopic meniscal repair with bioabsorbable arrows and concomitant anterior cruciate ligament (ACL) reconstruction. Of the 34 patients, 27 were male and 7 were female. Of the 38 menisci, 27 were medial and 11 were lateral. Second-look arthroscopy was performed for each patient while taking out the hardware for ACL reconstruction of the tibial side to evaluate the healing status of the repaired menisci. Postoperative MRI was done 2 days before or after second-look arthroscopy. Sagittal T1, T2 and PD images and coronal T2 and PD images were used as the main diagnostic serials. Second-look arthroscopy showed that surfaces of the repaired sites of all 38 menici were almost smooth. In all 38 cases the tail ends of meniscus arrows disappeared and in four patients new overlying injury of compartmental cartilage at the repaired side was detected. MRI results revealed that different serials had different diagnostic accuracy. Sagittal: T1 28.9%, PD 34.2%, T2 60.5%. Coronal: PD 36.8%, T2 65.8%. The double sides Grade 3 signal had a higher proportion in saggital T1 and PD serials, 47.4 and 39.5%, respectively, while lower in sagittal and coronal T2 serials, both 5.3%. MRI diagnostic accuracy was correlated positively with the follow-up time (P < 0.05). MRI has its limitation in evaluating the status of menisci repaired with bioabsorbable arrows, especially for PD and T1 serials. T2 serials have higher diagnostic accuracy than other serials. MRI diagnostic accuracy can be improved by prolonging follow-up time and might be improved by further classifying Grade 3 signal in terms of signal intensity and the shape of the signal margin. [ABSTRACT FROM AUTHOR]