SummaryBackground: after anterior cruciate ligament (ACL) reconstruction, it is necessary to integrate free tendon graft biologically to the bone. In the present study, to verify whether a structure identical to the normal ligament-bone insertion could be regenerated at the tendon-bone interface without bone tunnel, we designed ACL reconstruction model without a tibial bone tunnel. Moreover, to enhance the integration process in this model, bone marrow-derived mesenchymal stem cells (bMSCs) were transplanted, and histological changes investigated. Our first hypothesis was that the grafted tendon would be anchored at part of the tendon-bone interface even if a bone tunnel was not created. Second hypothesis was that application of bMSCs at the tendon-bone interface would yield results histologically superior to those in controls. Methods: bilateral ACL reconstruction using our originally designed method was performed. Autologous bMSCs with the carrier were transplanted between the bottom of the grafted tendon and the bone pit of the tibia in the experimental limb, whereas the control limb received the carrier on-

PurposeTo investigate the usefulness of the “inducer grafting” technique for regeneration of the semitendinosus (ST) tendon after its harvest for anterior cruciate ligament (ACL) reconstruction.MethodsTwenty knees of 20 patients (mean age at the time of surgery, 23.1 years) underwent ACL reconstruction with a double bundle autograft using the ST tendon (7 patients) and the ST + the gracilis (G) tendons (13 patients).“Inducer grafting” techniqueAfter harvesting the ST tendon, a passing pin with a loop thread is inserted along with the tendon stripper. The passing pin is pulled out from the medial thigh and the loop thread retained. As an inducer graft, the ST tendon branch is used. After the ACL graft has been secured, the inducer graft is sutured to the pes anserinus and the proximal end passed through by pulling the thread out. Then the inducer graft is placed within the tendon canal. The mean follow-up period was 15 months. The presence and morphology of the regenerated ST tendon were examined by MRI. And the isometric hamstring strength was examined at 45°, 90° and 120° of knee flexion.ResultsOne month after the operation in all the patients, MRI demonstrated a low-intensity structure at the anatomical location of the ST, at the level of the superior pole of the patella and the joint line, apparently representing the regenerated ST tendon. Four months after the operation, the distal portion of the regenerated ST tendon had reached the pes anserinus in all patients. Twelve months after the operation, the regenerated ST tendon was hypertrophic in 19 of the 20 patients (95%). The isometric knee flexion torque of the ACL-reconstructed limb was significantly lower at 90° and 120° compared with the contralateral limb.ConclusionThese results suggest that the “inducer grafting” technique is able to improve the regeneration rate of the harvested ST tendon and promote hypertrophy of the regenerated ST tendon, extending all the way to the pes anserinus. However, this technique couldn’t improve the deficits in knee flexion torque after ACL reconstruction.

ObjectivesThe purpose of this study was to evaluate chronological changes in the collagen-type composition at tendon–bone interface during tendon–bone healing and to clarify the continuity between Sharpey-like fibres and inner fibres of the tendon.MethodsMale white rabbits were used to create an extra-articular bone–tendon graft model by grafting the extensor digitorum longus into a bone tunnel. Three rabbits were killed at two, four, eight, 12 and 26 weeks post-operatively. Elastica van Gieson staining was used to colour 5 µm coronal sections, which were examined under optical and polarised light microscopy. Immunostaining for type I, II and III collagen was also performed.ResultsSharpey-like fibres comprised of type III collagen in the early phase were gradually replaced by type I collagen from 12 weeks onwards, until continuity between the Sharpey-like fibres and inner fibres of the tendon was achieved by 26 weeks.ConclusionsEven in rabbits, which heal faster than humans, an observation period of at least 12 to 26 weeks is required, because the collagen-type composition of the Sharpey-like fibre bone–tendon connection may have insufficient pullout strength during this period. These results suggest that caution is necessary when permitting post-operative activity in humans who have undergone intra-bone tunnel grafts.

There is controversy about the treatment for unstable full radial posterior lateral meniscus tears, particularly that involving the posterior root. Some surgeons have advocated repairing these types of meniscus tears using various techniques, but their methods are somewhat technical. We developed the technique for an all-inside repair for full radial posterior lateral meniscus tears using the Meniscal Viper (Arthrex, Naples, FL). A doubled thread is passed through 1 edge of the radial tear by the Meniscal Viper and is kept in place without tying the knot. The Meniscal Viper is used again to set a new thread, repeating the same procedure to another edge of the tear. At this step, 2 doubled threads are passed through each stump of the tear, and both a loop end and 2 free ends of each thread are located outside of the joint. Then, 2 doubled threads pass the third thread into its own loop, pulling it out. Finally, the third thread becomes the mattress suture over the radial tear site and is fastened by sliding knot techniques. This procedure makes it easy to strictly, smoothly, and less invasively shorten the gap by drawing each stump of the meniscus in the direction of the circumference.

The AMB is thicker than the PLB, showing a constant correlation in the normal ACL. This suggests that the anteromedial graft must be thicker than the posterolateral graft at least in actual operations.