Biomedical subjects

Hirotsugu Muratsu

Publications and source records attributed to Hirotsugu Muratsu.

15 recordsLinked to original sources

PubMed2007

Reliability and usefulness of a new in vivo measurement system of the pivot shift.

Residual pivot shift after ACL reconstruction is a crucial factor related to poor clinical outcome. However, no method exists that is able to evaluate pivot shift quantitatively and noninvasively. We propose a new measurement system for the pivot shift test using an electromagnetic device and have evaluated its reliability and clinical usefulness. Posterior translation, lateral translation and maximum velocity during the reduction phase of pivot shift were calculated and used as parameters for evaluation. In measurement system analysis, discrepancies of motion between the bones and the sensors were minimal, while reproducibility in repeated measurement was acceptable. Next, clinical usefulness was evaluated by correlating the values obtained by kinematic measurement with the clinical grade. We found differences in each of the measured parameters among clinical grades. These data suggest the system is a valuable measurement tool for clinical evaluation of the pivot shift test.

Anterior Cruciate Ligament↗

PubMed2006

High-resolution MRI using a microscopy coil for the diagnosis of recurrent lateral patellar dislocation.

PURPOSE: Magnetic resonance imaging (MRI) has been commonly used for the preoperative evaluation of recurrent lateral patellar dislocation (RLPD). The purpose of this study was to determine the usefulness of high-resolution MRI (HR-MRI) with a microscopy coil for diagnosing RLPD. MATERIALS AND METHODS: The study group consisted of 15 patients with clinically diagnosed RLPD and 10 normal volunteers. All studies were performed on a 1.5-T MR system. First, conventional MRIs of the whole knee joint were obtained using the knee coil. Then HR-MRI scans using a microscopy coil in the medial aspect of the patella were obtained at the level of the superior pole of the patella, targeting the medial patellofemoral ligament (MPFL). The acquired HR-MRIs with RLPD were reviewed concerning the MPFL injury and the patellar injury. RESULTS: The MPFL was distinguished as a separate ligament, and the layer structure of the patellar cartilage was visualized clearly in all volunteers. The MPFL injury was visualized in 12 cases (87%); it included discontinuity, thickening, and loosening. The patellar injury was visualized in 11 cases (73%), which included dissecans of the medial margin and cartilage injuries. CONCLUSION: HR-MRI with a microscopy coil provides precise information of the MPFL and patellar cartilage injury for the diagnosis of RLPD.

Adolescent↗

PubMed2006

Joint gap kinematics in posterior-stabilized total knee arthroplasty measured by a new tensor with the navigation system.

BACKGROUND: The management of soft tissue balance during surgery is essential for the success of total knee arthroplasty (TKA) but remains difficult, leaving it much to the surgeon's feel. Previous assessments for soft tissue balance have been performed under unphysiological joint conditions, with patellar eversion and without the prosthesis only at extension and 90 deg of flexion. We therefore developed a new tensor for TKA procedures, enabling soft tissue balance assessment throughout the range of motion while reproducing postoperative joint alignment with the patellofemoral (PF) joint reduced and the tibiofemoral joint aligned. Our purpose in the present study was to clarify joint gap kinematics using the tensor with the CT-free computer assisted navigation system. METHOD OF APPROACH: Joint gap kinematics, defined as joint gap change during knee motion, was evaluated during 30 consecutive, primary posterior-stabilized (PS) TKA with the navigation system in 30 osteoarthritic patients. Measurements were performed using a newly developed tensor, which enabled the measurement of the joint gap throughout the range of motion, including the joint conditions relevant after TKA with PF joint reduced and trial femoral component in place. Joint gap was assessed by the tensor at full extension, 5 deg, 10 deg, 15 deg, 30 deg, 45 deg, 60 deg, 90 deg, and 135 deg of flexion with the patella both everted and reduced. The navigation system was used to obtain the accuracy of implantations and to measure an accurate flexion angle of the knee during the intraoperative joint gap measurement. RESULTS: Results showed that the joint gap varied depending on the knee flexion angle. Joint gap showed an accelerated decrease during full knee extension. With the PF joint everted, the joint gap increased throughout knee flexion. In contrast, the joint gap with the PF joint reduced increased with knee flexion but decreased after 60 deg of flexion. CONCLUSIONS: We clarified the characteristics of joint gap kinematics in PS TKA under physiological and reproducible joint conditions. Our findings can provide useful information for prosthetic design and selection and allow evaluation of surgical technique throughout the range of knee motion that may lead to consistent clinical outcomes after TKA.

Aged↗

PubMed2006

Clinical values in computer-assisted total knee arthroplasty.

Thirty posterior stabilized total knee prostheses implanted using a computed tomography-free navigation system were compared to a control group of 30 matched total knee prostheses of the same type implanted via a classical, surgeon-controlled technique. The accuracy of the implantations in relation to the mechanical axis in the navigation group was superior to that of the manual group. Early two-year clinical results including range of motion and Knee Society Clinical Rating Score were equally good compared to the manual group. However, potential long-term outcome and functional improvement require further investigation.

Aged↗

PubMed2005

A comparison of bone-patellar tendon-bone and bone-hamstring tendon-bone autografts for anterior cruciate ligament reconstruction.

BACKGROUND: Most of the previous comparative studies between patellar tendon and hamstring tendon anterior cruciate ligament grafts compared grafts of different constructs fixed with different methods. PURPOSE: To compare patellar tendon and hamstring tendon grafts with the same fixation method used to reconstruct the anterior cruciate ligament. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: During the reconstructive procedure, the hamstring tendon graft was prepared as a bone-hamstring-bone graft; both bone-patellar tendon-bone and bone-hamstring-bone grafts were fixed with interference screws. Eighty consecutive patients who underwent anterior cruciate ligament reconstruction were randomly assigned to either bone-patellar tendon-bone or bone-hamstring-bone groups. Follow-up examinations were performed for at least 5 years postoperatively. Seventy-two of the 80 patients (37 patients in the bone-patellar tendon-bone group and 35 in the bone-hamstring-bone group) were evaluated, with a mean follow-up period of 87.0 and 80.8 months, respectively. Follow-up examinations were performed using the International Knee Documentation Committee knee ligament standard and subjective knee forms. RESULTS: The mean KT-1000 arthrometer evaluation results showed no significant difference between the bone-patellar tendon-bone and bone-hamstring-bone groups (1.2 +/- 2.1 mm and 1.7 +/- 1.4 mm, respectively; P = .24). However, symptoms related to graft harvest (anterior kneeling pain) were more frequently observed in the bone-patellar tendon-bone group, and unsatisfactory results were correlated with severe kneeling pain in 3 patients from this group (P = .0056). Significant hamstring muscle weakness without complaint of functional deficit was found in the bone-hamstring-bone group (P = .0045). CONCLUSION: Bone-hamstring-bone grafts were shown to reduce the risk of problems at the graft harvest site compared to bone-patellar tendon-bone grafts, with comparable results in the remaining clinical parameters tested.

Adolescent↗

PubMed2005

Mechanical evaluation of a soft tissue interference screw with a small diameter: significance of graft/bone tunnel cross-sectional area ratio.

The purpose of this study is to evaluate the mechanical properties of a graft fixation using a small diameter soft tissue interference screw and analyze the factors affecting the fixation strength. Forty porcine knees were used. A bone tunnel, either 4.5 mm (n=40) or 5.0 mm (n=40) in diameter, was created in the bone block obtained from the proximal tibia or the distal femur. A patella-patellar tendon specimen with varied width was harvested, and the distal end of the patellar tendon was fixed within the bone tunnel using a small diameter soft tissue interference screw (4 x 15 mm). Then, the patella-patellar tendon-bone block complex was loaded until failure occurred and the maximum load was measured. As potential influential factors on the fixation strength, the insertion torque, bone mineral density of the bone block, and graft/tunnel cross-sectional area ratio (GTR) of each specimen were calculated. A significant correlation between the maximum failure load and the insertion torque was demonstrated. The quadratic regression analysis showed a statistically significant correlation between the failure load and the GTR. Optimal GTR for achieving high fixation strength was approximately 80%. When used in appropriate conditions, the mean failure load was 177 N for the 4.5 mm screw and 180 N for the 5 mm screw. The use of a small diameter interference screw for the fixation of a tendon graft to a bone is clinically feasible. Our research showed that the selection of appropriate fitting conditions is an important factor for optimizing the properties of the fixation.

Anatomy, Cross-Sectional↗

PubMed2005

Proprioceptive recovery of patients with cervical myelopathy after surgical decompression.

STUDY DESIGN: A prospective observational study. OBJECTIVES: To determine whether proprioceptive deficit recovers after surgery and whether proprioceptive evaluation can predict functional outcome in cervical myelopathy patients. SUMMARY OF BACKGROUND DATA: Proprioceptive sensation plays an important role in smooth, coordinated movement of the limbs. Information about proprioception ascends through the dorsal columns in the spinal cord. In severe compressive myelopathy, proprioceptive ability would be reduced and could be improved after surgical decompression. However, there have been few studies concerning proprioceptive impairment in cervical myelopathy. MATERIALS AND METHODS: The study group included 26 cervical myelopathy patients who underwent posterior surgical decompression. Knee proprioception was assessed by joint position sense, which was evaluated by measuring the error angle when the subjects tried to reproduce the predetermined angle by extension and by flexion. Proprioceptive deficit in the study group was evaluated, compared with age-matched normal subjects. Postoperative recovery and correlation to functional status was analyzed in the study group. The Japanese Orthopedic Association (JOA) scores were used for functional evaluation. RESULTS: The error angles were significantly higher in the study group than those in the control group before surgery. All patients in the study group finally had improvement of the error angles by a year after surgery. The average of error angles in the study group was improved 2 weeks after surgery; however, no changes were observed later. There was significant correlation between the improvement rate of the error angles 2 weeks after surgery and that of the JOA scores 2 years after surgery. There were 9 patients who had worsened proprioception 2 weeks after surgery either by extension or by flexion, all of whom had poor functional outcome. CONCLUSIONS: Knee proprioception was impaired in cervical myelopathy and recovered after surgical posterior decompression. Proprioceptive improvement at 2 weeks correlates with the degree of improvement in JOA scores at 2 years after surgery.

Adult↗

PubMed2005

Impaired joint proprioception in patients with cervical myelopathy.

STUDY DESIGN: Prospective clinical study. OBJECTIVES: To evaluate impairment of proprioception quantitatively in patients with cervical myelopathy. SUMMARY OF BACKGROUND DATA: Sensory information regarding proprioception ascends through the posterior columns in the spinal cord. Damage to these columns causes proprioceptive loss in patients with spondylotic myelopathy. Nevertheless, there have been few studies regarding proprioception in patients with myelopathy. METHODS: The authors evaluated knee proprioception in 54 cervical myelopathy patients and compared results with those of 54 age-matched healthy volunteers. Knee proprioception was assessed by joint position sense, represented by the error angles when patients reproduced predetermined angles of knee flexion. RESULTS: The average absolute angle error of right and left knee with the predetermined position of 30 degrees of knee flexion was 2.5 +/- 1.8 (mean +/- standard deviation) and 1.8 +/- 1.2 degrees and with the predetermined 60 degrees of flexion, 4.7 +/- 2.8 and 2.8 +/- 1.4 degrees in the myelopathy and control groups, respectively. The average absolute angular errors in the myelopathy group were significantly higher than those in the control group for each predetermined knee position (P < 0.01). CONCLUSIONS: Proprioceptive ability is impaired in patients with cervical myelopathy. Position sense can be assessed by measuring the angular error when reproducing criterion positions, and the results may reflect the severity of cervical myelopathy. Thus, the present method of measuring proprioception is easy to perform and useful for quantitative assessment of the severity of cervical myelopathy.

Adult↗

PubMed2005

Symptomatic anomalous insertion of the medial meniscus.

We report a case of a young athlete with a symptomatic anomaly of the medial meniscus. An anomalous portion in conjunction with the anterior horn of the medial meniscus extended to the intercondylar notch of the femur through the surface of the anterior cruciate ligament. This anomalous band was arthroscopically resected and the symptoms completely disappeared. Histologic examination showed fibrocartilaginous tissue compatible with meniscus.

Adolescent↗

PubMed2005

Cerebellar infarction resulting from vertebral artery occlusion associated with a Jefferson fracture.

Neurologic deficit secondary to a Jefferson fracture is rare, as the fracture fragments tend to spread outward. To the authors' knowledge, only five cases of vertebral artery injury associated with C1 fracture have been reported. A 75-year-old man with diffuse spinal hyperostosis hit the top of his head and sustained a Jefferson fracture. The patient presented with vertigo and slurred speech. Magnetic resonance (MR) imaging demonstrated cerebellar infarction, and MR angiography (MRA) showed bilateral vertebral artery occlusion associated with a Jefferson fracture. The patient was placed in a halo vest for a total of 11 weeks and treated with anticoagulant therapy. Vertigo gradually improved, and the patient was able to walk with a cane. Previously slurred speech was completely resolved. This case demonstrates that a Jefferson fracture can cause vertebral artery occlusion, resulting in cerebellar infarction. The clinician should be aware of the possibility and implications of vertebral artery injuries, especially if a fracture involving the foramen transversarium with displacement is documented or if there is a neurologic deficit above the level of injury. Advances in noninvasive imaging such as MRA will facilitate accurate evaluation of these potentially life-threatening vascular injuries.

Aged↗

PubMed2004

The load of an implanted graft during and after fixation in anterior cruciate ligament reconstruction.

Although the importance of initial graft load has been discussed in the literature, it has not been confirmed whether a surgeon can provide the desired load to an implanted graft in anterior cruciate ligament reconstruction. The purpose of this study was to compare the set force (initial load given to the graft before fixation) and residual load in the implanted graft using three different fixation techniques. A total of ninety porcine knees were tested using bone-patellar tendon-bone autograft. Each bone-tendon-bone autograft was fixed to the tibia with either the interference-fit screw, fixation post, or button technique. Graft load was monitored during fixation procedures, and for 10 min after fixation. Residual graft load with each fixation technique exhibited unique features. Highest graft load was obtained by the interference-screw fixation technique; however, the graft was usually over-loaded beyond the intended set force with this technique. In the fixation-post technique, the load of the graft increased while the screw was retightened. The graft load in the button-fixation technique was low, probably due to slight slippage of the button. When the graft was fixed under maximum manual tension, the graft loads at completion of fixation for the interference fit screw, fixation post, and button techniques were 116.3, 54.2, and 25.9 N respectively.

Animals↗

PubMed2004

Prosthetic alignment and sizing in computer-assisted total knee arthroplasty.

We implanted 60 posterior stabilized total knee prostheses (P.F.C. Sigma, DePuy, Warsaw, USA). In 30 cases, we used a CT-free navigation system (Vector Vision, Brain LAB, Heimstetten, Germany), and in 30 matched-paired controls, we used a conventional manual implantation. We compared postoperative long-leg radiographs in the two groups. The results revealed a significant difference in favor of navigation. In addition, we compared the preoperative anteroposterior dimension of the femoral condyle with the postoperative value. While there were no significant differences in the preoperative anteroposterior dimension of the femoral condyle between the two groups, the postoperative value in the navigation group was significantly larger than that of the preoperative value. Therefore, surgeons using navigation systems should guard against the possibility of oversizing when determining the size of the femoral component.

Aged↗

PubMed2004

An expanding cervical synovial cyst causing acute cervical radiculopathy.

Synovial cysts of the cervical spine occur infrequently in the spinal canal and are most often associated with degenerative facet joints. Despite the prevalence of degenerative spinal disease, symptomatic synovial cysts are extremely uncommon. We report a rare case that showed an exacerbation of a cervical radiculopathy due to an acute expansion of the synovial cyst. Magnetic resonance (MR) images originally revealed a small cystic extradural lesion when the patient presented with neck pain and slightly numbness in the right hand. The patient's complaints subsequently subsided after administration of pain killers. However, 2 weeks after this, the patient experienced a spontaneous, sudden, severe radiating pain into the right arm without any accompanying cervical injury. MR images showed that the cyst had become markedly increased in size in the intervening 4 weeks and compressed the spinal cord laterally. Because the arm pain was so severe and neurologic examinations revealed the paralysis of the C8 nerve root, the synovial cyst was excised surgically and a good clinical outcome achieved. Thus, even if symptoms are mild and the size of the synovial cyst is small, acute expansion of the cyst might be rarely observed and careful management, including surgical consideration, is needed.

Acute Disease↗

PubMed2003

Avulsion fracture of the posterior oblique ligament associated with acute tear of the medial collateral ligament.

The term posterior oblique ligament was proposed in 1973 but the specific anatomy of this region has been controversial. It has been concluded that the posterior oblique ligament is separated from the medial collateral ligament, each with distinctly different bony attachment points. In this article, we report a posterior oblique ligament avulsion fracture associated with a medial collateral ligament rupture.

Accidents, Traffic↗

PubMed2002

Low-intensity pulsed ultrasound enhances early healing of medial collateral ligament injuries in rats.

OBJECTIVE: To investigate the effect of low-intensity pulsed ultrasound exposure on the healing of injured medial collateral ligaments. METHODS: Thirteen male Sprague Dawley rats were used in the study. After surgical transection of the bilateral medial collateral ligaments, the ligament of 1 knee received low-intensity pulsed ultrasound exposure (30 mW/cm2 for 20 minutes daily), whereas no ultrasound was applied to the contralateral knee (control side). Eight rats were killed at 12 days after surgery, and 5 rats were killed at 21 days. The bilateral knees of 5 rats were used for mechanical testing at each of the 2 periods, and 12-day specimens of the remaining 3 rats were prepared for the electron microscopic examination. The knees of 5 additional rats were used to obtain mechanical data of the normal uninjured medial collateral ligament. RESULTS: On the 12th day, the low-intensity pulsed ultrasound-treated side exhibited significantly superior mechanical properties when compared with the control side in ultimate load, stiffness, and energy absorption (P < .05). However, the treatment did not afford any mechanical advantage when tested on the 21st day. The mean diameter of the fibril was significantly larger on the treatment side than on the control side (P < .05). CONCLUSIONS: Low-intensity pulsed ultrasound exposure is effective for enhancing the early healing of medial collateral ligament injuries.

Animals↗