Hidenori Otsubo

Direct anterior cruciate ligament insertion to the femur assessed by histology and 3-dimensional volume-rendered computed tomography.

PURPOSE The purpose of this study was to histologically identify the direct and indirect insertion of the femoral anterior cruciate ligament (ACL) insertion. Furthermore, we quantitatively measured the direct femoral insertion area by use of the 3-dimensional (3D) volume-rendered (VR) computed tomography (CT) model. METHODS By use of 8 intact cadaveric knees, the lateral femoral condyle including the ACL attachment was sectioned for histologic examination in 3 oblique-axial planes parallel to the roof of the intercondylar notch and in the sagittal planes. Before sectioning, these knees had been subjected to CT to obtain 3D VR images of the femur. Once the direct insertion of the ACL was identified on each histologic section, the corresponding image was superimposed on the corresponding CT image. RESULTS The direct ACL insertion, in which dense collagen fibers were connected to the bone by the fibrocartilaginous layer, was microscopically identified at the region between the posteromedial articular cartilage margin of the lateral femoral condyle and the linear bony ridge 7 to 10 mm anterior to the articular cartilage margin. Meticulous comparison of histologic analysis and the 3D VR CT model showed that the ACL direct insertion coincided with a crescent-shaped hollow just behind the linear bony ridge. The direct insertion measured 17.4 +/- 0.9 mm (mean +/- SD) in length, 8.0 +/- 0.5 mm in width, and 128.3 +/- 10.5 mm(2) in area. CONCLUSIONS The direct insertion of the ACL is located in the depression between the residents ridge and the articular cartilage margin on the lateral femoral condyle. It measured 17.4 +/- 0.9 mm in length, 8.0 +/- 0.5 mm in width, and 128.3 +/- 10.5 mm(2) in area. CLINICAL RELEVANCE Delineation of the ACL femoral direct insertion by 3D VR CT could be a useful tool for planning of accurate femoral tunnel positioning in anatomic ACL reconstruction.

Optimization of Graft Fixation at the Time of Anterior Cruciate Ligament Reconstruction: Part II: Effect of Knee Flexion Angle

Background There is no consensus about flexion angle of the knee at the time of graft fixation in anterior cruciate ligament reconstruction. Purpose To evaluate the effect of flexion angle at the final graft fixation on the positional relationship as well as the load between femur and tibia. Study Design Controlled laboratory study. Methods Six intact cadaveric knees were passively flexed and extended under 6 degrees of freedom with the robotic system developed in our laboratory, while their 3-dimensional paths were recorded. Anterior cruciate ligament reconstruction was performed with a single-socket technique using autogenous quadrupled hamstring tendons, while the graft was fixed at 0° (group A) 20° (group B) or 90° (group C) with a constant initial tension of 44 N. The knees then repeated the same movement as before while the relative position between femur and tibia was recorded. The load in the femorotibial joint was also calculated based on the principle of superposition. Results Posterior displacement of the tibia compared with the normal knee was the smallest in group B at all flexion angles, while the load between tibia and femur in group B was also the smallest and the closest to the normal knee. Conclusion As the positional relationship as well as the load between femur and tibia in group B was the closest to that in the normal knee, 20° of flexion is the most desirable of the positions tested for graft tensioning and fixation at the time of anterior cruciate ligament reconstruction. Clinical Relevance The tibia-femur position is well retained when the graft was fixed at 20° of flexion in anterior cruciate ligament reconstruction.

Optimization of Graft Fixation at the Time of Anterior Cruciate Ligament Reconstruction Part I: Effect of Initial Tension

Background Although anterior cruciate ligament (ACL) reconstructions are frequently performed, little is known about the effect of initial tension on an ACL graft at the time of its fixation. Purpose The objective of this study was to evaluate the effects of initial tension on the relative position and the load between femur and tibia during passive motion. Study Design Controlled laboratory study. Methods Seven cadaveric knees underwent a passive flexion-extension movement from 0° to 90° with a robotic system developed in the authors’ laboratory under 6 degrees of freedom, while their 3-dimensional paths were recorded. A single-socket ACL reconstruction was performed with an autogenous quadrupled hamstring tendon graft, while the knees underwent the same movement as before with the initial graft tension of 22 N (group A), 44 N (group B), or 88 N (group C) at 20°. The relative position between the femur and the tibia was recorded, and the load in the femorotibial joint was calculated using the principle of superposition. Results The tibia in group C was most posteriorly positioned among the 3 groups (an average posterior translation of 0.6, 1.3, and 2.6 mm in groups A, B, and C, respectively). The tibia also moved proximally and laterally with external and valgus rotation with an increase in initial tension, and consequently the load in the femorotibial joint increased at ail flexion angles. Conclusion With an increase in initial tension, the tibia moved posterolaterally with external and valgus rotation, and consequently the contact force in the femorotibial joint increased. Clinical Relevance Excessive initial tension at the time of ACL reconstruction may potentially bring deleterious effects to the articular surface, leading to cartilage degeneration.

The arrangement and the attachment areas of three ACL bundles

PurposeNormal anterior cruciate ligament (ACL) can be divided into three fiber bundles—i.e., anteromedial (AM), intermediate (IM), and posterolateral (PL) bundles. However, their arrangement and attachment areas had remained unclear. The purpose of this study was to clarify the arrangement of these three ACL fiber bundles and their attachment sites, and to provide information on the tunnel placement in anatomical triple bundle ACL reconstruction.MethodsSeven non-embalmed human frozen knees were used. ACL fibers were bluntly divided into three bundles. A different-colored thread was wound around each fiber bundle in a spiral. Macroscopical investigation was performed to clarify the arrangement of three ACL bundles. Each fiber bundle was carefully detached from the femur and tibia, and then the distribution of attachment sites of each fiber bundle was observed.ResultsIn knee extension, all bundles consisting of AM, IM and PL bundles ran parallel to each other in the lateral view from the medial side. The AM bundle overlapped with the IM bundle, whereas the PL bundle ran parallel to them on the distal aspects. As the knee flexion increased, the bundles became twisted around each other. On the tibial side, the attachment areas of three fiber bundles formed a triangular shape showing arrangements of AM, IM and PL bundles on the anteromedial, anterolateral and posterior aspects, respectively. On the femoral side, the PL bundle was attached on the distal-posterior areas; the IM bundle was attached distal-anterior to the AM bundle. They were arranged in a triangular shape on the tibia side as well.ConclusionThis study clarified the arrangement of three fiber bundles of ACL and detailed geographical locations of their attachment sites. The detailed anatomic description of the natural ACL attachment might suggest to surgeons where to make tunnels during anatomical double/triple bundle ACL reconstruction.

Ultrastructure of the three anterior cruciate ligament bundles

The anterior cruciate ligament (ACL) can be morphologically separated into not only two, but three bundles: the anteromedial‐medial bundle (AM‐MB), the anteromedial‐lateral bundle (AM‐LB), and the posterolateral bundle (PLB). Our hypothesis was that the three bundles differ in their microstructures. The purpose of this study was to clarify the microstructural differences among the three bundles. The normal ACLs of six fresh frozen cadavers were harvested. After the AM‐MB, AM‐LB, and PLB were identified, their fibril structures were analyzed using a transmission electron microscope. The fibril orientation, distribution pattern, and the mass average diameter of the fibrils (MAD) were compared among the AM‐MBs, AM‐LBs, and PLBs. The AM‐MB and AM‐LB fibrils were arranged mostly in the longitudinal direction, while the PLB fibrils were not aligned in a uniform direction. The fibril diameter distribution pattern of AM‐MBs showed a bi‐modal pattern due to the existence of small‐diameter (30‐40 nm) and large‐diameter fibrils (70‐80 nm), while that of the AM‐LBs and PLBs had a unimodal pattern with one prominent high peak at a diameter of 50‐60 nm. The mean MAD of the AM‐MBs (83.2 − 11.2 nm) was significantly larger than that of the PLBs (66.8 − 7.7 nm), while it showed no significant difference compared to that of the AM‐LBs (77.6 − 12.3 nm). The three ACL bundles have different ultrastructures. The AM‐MB predominantly includes thick, uni‐directionally oriented fibrils like tendons, while the PLB consists of thinner, multi‐directionally oriented fibrils. The AM‐LB shows an intermediate structure between the AM‐MB and the PLB. Clin. Anat. 28:910–916, 2015.

MRI depiction and 3D visualization of three anterior cruciate ligament bundles

The anterior cruciate ligament (ACL) is divided into three fiber bundles (AM‐M: anteromedial‐medial, AM‐L: anteromedial‐lateral, PL: posterolateral). We attempted to depict the three bundles of the human ACL on MRI images and to obtain 3‐dimensional visualization of them. Twenty‐four knees of healthy volunteers (14 males, 10 females) were scanned by 3T‐MRI using the fat suppression 3D coherent oscillatory state acquisition for the manipulation of imaging contrast (FS 3D‐COSMIC). The scanned images were reconstructed after the isotropic voxel data, which allows the images to be reconstructed in any plane, was acquired. We conducted statistical examination on the identification rate of the three ACL bundles by 2D planes. Segmentation and 3D visualization of the fiber bundles using volume rendering were performed. The triple‐bundle ACL was best depicted in the oblique axial plane. While the AM‐M and AM‐L bundles were clearly depicted in all cases, the PL bundle was not clearly visualized in two knees (8%). Therefore, the three ACL bundles were depicted in 22 knees (92%). The results of 3D visualization of the fiber arrangement agreed well with macroscopic findings of previous anatomical studies. 3T‐MRI and the isotropic voxel data from FS 3D‐COSMIC made it possible to demonstrate the identifiable depiction of three ACL bundles in nearly all cases. 3D visualization of the bundles could be a useful tool to understand the ACL fiber arrangement. Clin. Anat. 30:276–283, 2017. 2016 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

The in situ force in the calcaneofibular ligament and the contribution of this ligament to ankle joint stability

BACKGROUND Numerous biomechanical studies of the lateral ankle ligaments have been reported; however, the isolated function of the calcaneofibular ligament has not been clarified. We hypothesize that the calcaneofibular ligament would stabilize the ankle joint complex under multidirectional loading, and that the in situ force in the calcaneofibular ligament would change in each flexed position. METHODS Using seven fresh frozen cadaveric lower extremities, the motions and forces of the intact ankle under multidirectional loading were recorded using a 6-degree-of-freedom robotic system. On repeating these intact ankle joint complex motions after the calcaneofibular ligament transection, the in situ force in the calcaneofibular ligament and the contribution of the calcaneofibular ligament to ankle joint complex stability were calculated. Finally, the motions of the calcaneofibular ligament-transected ankle joint complex were recorded. FINDINGS Under an inversion load, significant increases of inversion angle were observed in all the flexed positions following calcaneofibular ligament transection, and the calcaneofibular ligament accounted for 50%-70% of ankle joint complex stability during inversion. The in situ forces in the calcaneofibular ligament under an anterior force, inversion moment, and external rotation moment were larger in the dorsiflexed position than in the plantarflexed position. INTERPRETATION The calcaneofibular ligament plays a role in stabilizing the ankle joint complex to multidirectional loads and the role differs with load directions. The in situ force of the calcaneofibular ligament is larger at the dorsiflexed position. This ligament provides the primary restraint to the inversion ankle stability.

Recurrent knee arthritis diagnosed as juvenile idiopathic arthritis with a 10-year asymptomatic period after arthroscopic synovectomy: a case report

IntroductionJuvenile idiopathic arthritis is a chronic inflammatory disease associated with arthritis of unknown etiology that begins before the age of 16 and persists for longer than 6 weeks. The frequency of recurrence after arthroscopic synovectomy in patients with oligoarthritis juvenile idiopathic arthritis was reported to be lower than that in patients with polyarthritis. However, recurrence in cases of oligoarthritis after arthroscopic knee synovectomy was shown to be 67% in one recent study and, furthermore, a shorter period free from recurrence was also reported after synovectomy. Here we report a child who suffered recurrent knee arthritis with a 10-year asymptomatic period after arthroscopic synovectomy.Case presentationA 12-year-old Japanese girl presented with normal birth and developmental history. At the age of 2 years she experienced joint swelling in both knees. Her symptoms continued and arthroscopic synovectomy was eventually performed. During the operation, rice bodies and thickening of the synovial membrane were observed; however, no definitive diagnosis was made. After a 10-year asymptomatic period, knee joint swelling recurred on one side without any cause. Arthroscopic synovectomy was beneficial in reducing the symptoms and in diagnosis.ConclusionsChildren who suffer prolonged joint swelling have a risk of juvenile idiopathic arthritis. Even if the symptoms heal and no definite diagnosis is made at the first treatment, informed consent is needed to make the patients understand the future risk of recurrent arthritis after even lengthy asymptomatic periods.

IGF-1 Gene Transfer to Human Synovial MSCs Promotes Their Chondrogenic Differentiation Potential without Induction of the Hypertrophic Phenotype

Mesenchymal stem cell- (MSC-) based therapy is a promising treatment for cartilage. However, repair tissue in general fails to regenerate an original hyaline-like tissue. In this study, we focused on increasing the expression levels for insulin-like growth factor-1 (IGF-1) to improve repair tissue quality. The IGF-1 gene was introduced into human synovial MSCs with a lentiviral vector and examined the levels of gene expression and morphological status of MSCs under chondrogenic differentiation condition using pellet cultures. The size of the pellets derived from IGF-1-MSCs were significantly larger than those of the control group. The abundance of glycosaminoglycan (GAG) was also significantly higher in the IGF-1-MSC group. The histology of the IGF-1-induced pellets demonstrated similarities to hyaline cartilage without exhibiting features of a hypertrophic chondrocyte phenotype. Expression levels for the Col2A1 gene and protein were significantly higher in the IGF-1 pellets than in the control pellets, but expression levels for Col10, MMP-13, ALP, and Osterix were not higher. Thus, IGF-1 gene transfer to human synovial MSCs led to an improved chondrogenic differentiation capacity without the detectable induction of a hypertrophic or osteogenic phenotype.

Repair of Acute Patellar Tendon Rupture Augmented with Strong Sutures

&NA; Rupture of the patellar tendon is an uncommon injury that requires acute surgical repair to restore the function of the knee. Multiple techniques for repair have been described in the literature. Complications with these repair techniques include rerupture and extensor lag caused by gap formation at the site of repair. Thus, many surgeons have suggested augmenting the standard repair. Several methods of augmentation have been described each with disadvantages. The purpose of this article was to present our case series of six patients with acute patella tendon ruptures treated by a novel procedure using strong sutures. In this method, eight strands of four‐strong sutures run within the tendon. At the patellar site, a combination of suture button and figure eight pattern techniques is used, avoiding stress concentration. The optimal tension is applied to each suture, so as the patella might be positioned at the original placement. Then all sutures are secured onto the tibia. Postoperatively with a mean follow‐up of 32.7 months (range: 25–48 months), all patients had a stable knee with mean flexion of 143.3 degrees (range: 140–150 degrees) and without any extension lag. With an improvement in the International Knee Documentation Committee score to 86.8 (range: 80–92), the excellent outcome was noted in all patients. The average postoperative Lysholm score was 98.8 (range: 97–100) and the average Kujala score was 95.2 (range: 92–97). All patients recovered to near‐normal strength and stability of the patellar tendon as well as restoration of function after the operation. This augmentation technique offers a distinct advantage over previous augmentation methods and materials, and may be especially useful in managing patellar tendon rupture caused by rheumatoid arthritis or other systemic conditions. For these reasons, we recommend this procedure for acute patellar tendon ruptures.