Takashi Soejima

An immunohistological study of the integration at the bone-tendon interface after reconstruction of the anterior cruciate ligament in rabbits

We studied bone-tendon healing using immunohistochemical methods in a rabbit model. Reconstruction of the anterior cruciate ligament was undertaken using semitendinosus tendon in 20 rabbits. Immunohistochemical evaluations were performed at one, two, four and eight weeks after the operation. The expression of CD31, RAM-11, VEGF, b-FGF, S-100 protein and collagen I, II and III in the bone-tendon interface was very similar to that in the endochondral ossification. Some of the type-III collagen in the outer layer of the graft, which was deposited at a very early phase after the operation, was believed to have matured into Sharpey-like fibres. However, remodelling of the tendon grafted into the bone tunnel was significantly delayed when compared with this ossification process. To promote healing, we believe that it is necessary to accelerate remodelling of the tendon, simultaneously with the augmentation of the ossification.

Analysis of strain distribution in the medial collateral ligament using a photoelastic coating method

The strain distribution over the entire medial collateral ligament (MCL) was measured using a photoelastic coating method. This new approach utilized a polyurethane monomer as a photoelastic coating film. The initial experiments investigating MCL strain measurement showed that this film had a high sensitivity for strain and good adhesion to the ligament. It was confirmed that strain distribution could be obtained qualitatively over the entire ligament using this method. The mechanism of MCL injury was studied by applying this polyurethane coating film to the entire MCL in a femur-MCL-tibia complex. When simple tension was applied to the complex, strain concentrations were centred at the tibial insertion site, and all the specimens ruptured at the MCL tibial insertion site. With application of a valgus bending moment, increased strain was seen in the MCL from the medial femoral condyle to the medial epicondyle. Histological analysis demonstrated midsubstance ligament ruptures in this same region. For both tests, rupture sites and increased strain concentration sites correlated. In addition, an impingement phenomenon of the MCL on the medial femoral condyle can be seen during application of valgus force, and this phenomenon may explain the higher incidence of MCL injuries on the femoral side seen in the clinical setting. This polyurethane coating method allows for direct and visual measurements, and can qualitatively measure the strain behaviour over the entire MCL surface. This new technique represents a significant improvement over previous point-by-point strain measurement methods.

Inducement of semitendinosus tendon regeneration to the pes anserinus after its harvest for anterior cruciate ligament reconstruction-A new inducer grafting technique

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.

Deterioration of the femoral articular surface after meniscal repair evaluated by second-look arthroscopy: comparison with partial meniscectomy

Abstract To evaluate whether meniscal repair can protect the cartilage deterioration, changes in articular cartilage of the involved compartment were evaluated by reviewing the videotapes recorded at the time of operations (33 meniscal repairs, 18 meniscectomies) and second-look arthroscopies. Meniscal repairs gave marginally better results than meniscectomies but the articular cartilage was often deteriorated in cases that had the incompletely healed meniscus or the unhealed meniscus. Although completely healed menisci restore the meniscal function and protect the articular damage, unsuccessful meniscal healings sometimes provoke degeneration of the articular cartilage.

Proline/arginine-rich end leucine-rich repeat protein converts stem cells to ligament tissue and Zn(II) influences its nuclear expression

Our objective was to facilitate ligament tissue reconstruction by characterizing the mechanism of expression of ligament tissue. To accomplish this, we searched for proteins specific to the tissue and introduced them into mesenchymal stem cells. In the two-dimensional phosphorescent gel electrophoresis, the spots in common with the normal human ligament tissue were selected after removing the spots of the normal bone tissue from those of the ossified tissue in the spinal ligament. Proline/arginine-rich end leucine-rich repeat protein (PRELP) was identified in ligament-specific locations by liquid chromatography-tandem mass spectrometry. Transfection of PRELP into mouse mesenchymal stem cells yielded ligament-like connective tissue comprised of parallel fibers. Thus, expression of the PRELP protein could reconstruct the ligament tissue. Since zinc-related proteins were found with high incidence as a result of an array analysis of PRELPs ProtoArray, it was considered that there is a relationship to the zinc metabolism. Tissue induction was mediated by the tumor necrosis factor (TNF)-α via the zinc pathway. PRELP may be a useful gene in syndesmoplasty, provided zinc is present for tissue reconstruction. Chromosome division becomes active with the addition of zinc, and rapid tissue induction takes place in the presence of zinc and TNF-α. Currently, the reconstruction of a ruptured ligament tissue is difficult, but we expect that the PRELP protein expression may facilitate this process. This study describes the discovery of the gene responsible for the differentiation of stem cells into ligament tissue. This important finding may lead to treatments for gonarthrosis, cruciate ligament, and periodontal ligament ruptures, and ossification of the posterior longitudinal ligament.

Regeneration of ring-shaped lateral meniscus after partial resection of discoid meniscus with anterior cruciate ligament reconstruction

INTRODUCTION The ring-shaped lateral meniscus is very rare. Although it is essentially known as a congenital anomaly, a central tear in an incomplete discoid meniscus or an old bucket-handle tear in a meniscus may be easily mistaken for a ring-shaped meniscus. We experienced a ring-shaped lateral meniscus that regenerated after partial resection of a discoid meniscus together with anterior cruciate ligament (ACL) reconstruction. PRESENTATION OF CASE A 37-year-old female patient still experienced unrelenting knee pain 6 months after ACL reconstruction and partial meniscectomy of a discoid lateral meniscus. A repeat arthroscopy was performed. The lateral tibial plateau was covered in the form of a ring by meniscus-like tissue. The meniscus-like tissue appeared to have regenerated inward toward the center from the stump after the partial meniscectomy and was connected from the anterior to posterior horn, forming an interhorn bridge. Partial meniscectomy was repeated. Histologically, the regenerated tissue was not meniscal, but comprised mature fibrocartilage; macroscopically; however, it was very similar to meniscal tissue. Two years after the initial operation, the patient had no complaints and experienced full return of function. DISCUSSION The reason for such regeneration is unknown, but may have been attributed to the specific intra-articular environment that developed after the ACL reconstruction. CONCLUSION This is the first report of regenerative development of a ring-shaped lateral meniscus. When a ring-shaped lateral meniscus is diagnosed, we must accurately determine whether it is a true congenital anomaly in consideration of the present case.

Chronological changes in the collagen-type composition at tendon-bone interface in rabbits.

Objectives The 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. Methods Male 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. Results Sharpey-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. Conclusions Even 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.

An All-Inside Repair for Full Radial Posterior Lateral Meniscus Tears

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.

Anatomic Oblong Double Bundle Anterior Cruciate Ligament Reconstruction.

Double-bundle anterior cruciate ligament (ACL) reconstruction using hamstring tendon grafts is a standard procedure for ACL injury. However, its clinical effectiveness is not always satisfactory. One cause of this was problems with the graft-tunnel healing of the posterolateral bundle (PLB) on the femur. To solve this problem, we devised a new anatomic ACL reconstruction technique to improve the graft-tunnel healing of the femoral PLB by using a single-bundle with one bone tunnel on the femoral side and a double-bundle on the tibial side. We have performed 40 procedures with excellent results and no cases of intra- or postoperative complication. This procedure can help improve the graft-tunnel healing around the femoral bone tunnel aperture for the PLB.

Inducement of tissue regeneration of harvested hamstring tendons in a rabbit model.

Objectives The objective of this study was to determine if the use of fascia lata as a tendon regeneration guide (placed into the tendon canal following harvesting the semitendinosus tendon) would improve the incidence of tissue regeneration and prevent fatty degeneration of the semitendinosus muscle. Materials and Methods Bilateral semitendinosus tendons were harvested from rabbits using a tendon stripper. On the inducing graft (IG) side, the tendon canal and semitendinosus tibial attachment site were connected by the fascia lata, which was harvested at the same width as the semitendinosus tendon. On the control side, no special procedures were performed. Two groups of six rabbits were killed at post-operative weeks 4 and 8, respectively. In addition, three healthy rabbits were killed to obtain normal tissue. We evaluated the incidence of tendon tissue regeneration, cross-sectional area of the regenerated tendon tissue and proportion of fatty tissue in the semitendinosus muscle. Results At post-operative week 8, the distal end of the regenerated tissue reached the vicinity of the tibial insertion on the control side in two of six specimens. On the IG side, the regenerated tissue maintained continuity with the tibial insertion in all specimens. The cross-sectional area of the IG side was significantly greater than that of the control side. The proportion of fatty tissue in the semitendinosus muscle on the IG side was comparable with that of the control side, but was significantly greater than that of the normal muscle. Conclusions Tendon tissue regenerated with the fascia lata graft was thicker than naturally occurring regenerated tissue. However, the proportion of fatty tissue in the semitendinosus muscle was greater than that of normal muscle. Cite this article: K. Tabuchi, T. Soejima, H. Murakami, K. Noguchi, N. Shiba, K. Nagata. Inducement of tissue regeneration of harvested hamstring tendons in a rabbit model. Bone Joint Res 2016;5:247–252. DOI: 10.1302/2046-3758.56.2000585.