Takuma Kobayashi

The Pullout Strength of Pedicle Screws Following Redirection After Lateral Wall Breach or End-plate Breach.

Study Design. Using fresh cadavers, the biomechanical testing were used to examine the pullout strength of each pedicle screw. Objective. The aim of this study was to evaluate pullout strength of (1) a redirected pedicle screw following lateral wall breach; (2) a redirected pedicle screw following end-plate breach; and (3) a pedicle without redirection after end-plate breach without redirection. Summary of Background Data. Screw malposition, such as lateral wall breach or end-plate breach, is one of the main pitfalls of inserting pedicle screws. Methods. From 17 fresh spines, 54 vertebrae were harvested. In each vertebra on one pedicle, the screw was inserted correctly down the axis of the pedicle, while on the other pedicle, the screw was inserted to breach the lateral wall or the end-plate. The 18 pedicle screws that breached the lateral wall were then removed and redirected along the correct axis of the pedicle. The 18 pedicle screws that breached the end-plate were removed and redirected along the correct axis of the pedicle. The 18 other pedicle screws that had breached the end-plate were not removed. The pullout force of pedicle screws was measured. Results. First, the mean pullout strength for the redirected screws following lateral wall breach was 24.0% less as compared with the correctly aligned screws. Second, the mean pullout strength for the redirected screws following end-plate breach was 23.3% less as compared with the correctly aligned screws. Third, the mean pullout strength for the pedicle screws end-plate breach was 7.6% less as compared with the correctly aligned screws. Conclusion. The pullout strength of redirected pedicle screws after either a lateral pedicle breach or end-plate breach is significantly less than the pullout strength of correctly aligned screw. A pedicle screw that is not redirected after end-plate breach is weaker than a pedicle screw correctly aligned; however, the difference is not significant. Level of Evidence: N/A

Effects of different movement directions on electromyography recorded from the shoulder muscles while passing the target positions

PURPOSE We compared electromyography (EMG) recorded from the shoulder joint muscles in the same position for different movement directions. METHODS Fifteen healthy subjects participated. They performed shoulder elevation from 0° to 120°, shoulder depression from 120° to 0°, shoulder horizontal adduction from -15° to 105°, and shoulder horizontal abduction from 105° to -15°. The target positions were 90° shoulder elevation in the 0°, 30°, 60°, and 90° planes (0°, 30°, 60°, and 90° positions). EMG signals were recorded from the supraspinatus (SSP) muscle by fine-wire electrodes. EMG signals from the infraspinatus (ISP), anterior deltoid, middle deltoid, and posterior deltoid muscles were recorded using active surface electrodes. RESULTS During elevation and horizontal abduction, the SSP showed significantly higher activity than that shown during depression and during horizontal adduction in the 0°, 30°, and 60° positions. During elevation, the ISP showed significantly higher activity than during depression and during horizontal adduction in the 90° position. During horizontal abduction, the ISP showed significantly higher activity than during depression in the 90° position. CONCLUSIONS When the movement tasks were performed in different movement directions at the same speed, each muscle showed characteristic activity.

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.

Tibiotalocalcaneal Arthrodesis Using a Soft Tissue–Preserved Fibular Graft for Treatment of Large Bone Defects in the Ankle

Background: Pathogenesis of ankle disorders with a large bone defect is varied and treatment for those problems is challenging for orthopaedic surgeons. The aims of this study were to present an operative technique of arthrodesis for the reconstruction of the ankle and hindfoot with a large bone defect using a soft tissue–preserved fibular strut graft and to report outcomes of consecutively treated patients. Methods: Twelve feet from 11 patients, including feet with aseptic necrosis of the talus and total ankle implant loosening, were treated. Bone defects were filled using iliac bone and/or resected fibula and tibiotalocalcaneal arthrodesis was performed using a retrograde intramedullary nail. A modified transfibular approach was used to expose the affected joint while preserving the lateral to posterior skin and soft tissues on the fibula. The periods of bony fusion and outcomes were radiographically and clinically evaluated. The mean follow-up period was 33.4 months. Results: Bony fusion was achieved within 3 months in all cases. Coronal and sagittal alignments were acceptable, and the mean American Orthopaedic Foot & Ankle Score improved from 53.8 to 75.5 at the final follow-up. All patients graded their results of treatment as “satisfied.” Conclusion: This procedure did not require special techniques and it should be applicable to complicated cases with large bone defects. High fusion rates that we believe are due to preserving blood supply to the fibular graft can be expected with preservation of the hindfoot height. Level of Evidence: Level IV, case series.

Three-dimensional analysis of tarsal bone response to axial loading in patients with hallux valgus and normal feet

Background: Patients with hallux valgus present a variety of symptoms that may be related to the type of deformity. Weightbearing affects the deformities, and the evaluation of the load response of tarsal bones has been mainly performed using two‐dimensional plane radiography. The purpose of this study was to investigate and compare structural changes in the medial foot arch between patients with hallux valgus and normal controls using a computer image analysis technique and weightbearing computed tomography data. Methods: Eleven patients with hallux valgus and eleven normal controls were included. Computed tomograms were obtained with and without simulated weightbearing using a compression device. Computed tomography data were transferred into a personal computer, and a three‐dimensional bone model was created using image analysis software. The load responses of each tarsal bone in the medial foot arch were measured three‐dimensionally and statistically compared between the two groups. Findings: Displacement of each tarsal bone under two weightbearing conditions was visually observed by creating three‐dimensional bone models. At the first metatarsophalangeal joint, the proximal phalanges of the hallux valgus group showed significantly different displacements in multiple directions. Moreover, opposite responses to axial loading were also observed in both translation and rotation between the two groups. Interpretation: Weightbearing caused deterioration of the hallux valgus deformity three‐dimensionally at the first metatarsophalangeal joint. Information from the computer image analysis was useful for understanding details of the pathology of foot disorders related to the deformities or instability and may contribute to the development of effective conservative and surgical treatments. Highlights:Load responses of tarsal bone were measured three‐dimensionally.Those data were compared between hallux valgus patients and normal controls.Weightbearing computed tomography data were acquired from the two groups.The first metatarsophalangeal joint showed significantly different displacements.Weightbearing deteriorated the deformity three‐dimensionally at this joint.

Modified distal tibial oblique osteotomy for osteoarthritis of the ankle: Operative procedure and preliminary results

BACKGROUND Low tibial osteotomy is an effective joint-preserving surgery for ankle arthritis. However, poor postoperative wound healing, infection, and delayed or non-union of bones remain significant concerns. We describe a modified distal tibial oblique osteotomy procedure and report preliminary results for varus ankle arthritis. METHODS The osteotomy path consisted of an oblique doglegged line from the lateral end of the distal tibia to a proximal point about one-third from the lateral edge and continuing along an arc defined by virtual coronal-plane rotation of the doglegged line to the medial edge. After osteotomy, the distal tibial fragment was rotated distally in the coronal plane for realignment while maintaining contact with the proximal tibia and the distal tibial fragment. The resulting wedge-shaped gap was filled with artificial bone blocks and tibial bone projecting medially from rotation. A locking plate was then applied for stabilization. We evaluated 7 ankles from 6 osteoarthritis patients both clinically and radiographically following this procedure. RESULTS Bone union was achieved within 3 months for all patients. The Japanese Society for Surgery of the Foot ankle-hindfoot scale improved from a mean of 38.4 points preoperatively to 85.7 points at the latest follow-up. No wound healing problems, infections, or nerve disturbances were observed. Multiple radiographic parameters were also improved following the operation. CONCLUSIONS This procedure maintains close bone contact for better postoperative union, obviates the need for iliac bone harvesting, and reduces tension on medial soft tissue. We believe these modifications are potential advantages for achieving stable results in patients with ankle osteoarthritis.

Effect of Initial Graft Tension During Calcaneofibular Ligament Reconstruction on Ankle Kinematics and Laxity

Background: Although a variety of surgical procedures for lateral ankle ligament reconstruction have frequently been reported, little is known about the effects of initial graft tension. Purpose/Hypothesis: The purpose was to investigate the effects of initial graft tension in calcaneofibular ligament (CFL) reconstruction. It was hypothesized that a high degree of initial graft tension would cause abnormal kinematics, laxity, and excessive graft tension. Study Design: Controlled laboratory study. Methods: Twelve cadaveric ankles were tested with a 6 degrees of freedom robotic system to apply passive plantarflexion-dorsiflexion motion and multidirectional loads. A repeated-measures experiment was designed with the CFL intact, CFL transected, and CFL reconstructed with 4 initial tension conditions (10, 30, 50, and 70 N). The 3-dimensional path and reconstructed graft tension were simultaneously recorded. Results: The calcaneus in CFL reconstruction with an initial tension of 70 N had the most eversion relative to the intact condition (mean eversion translations of 1.2, 3.0, 5.0, and 6.2 mm were observed at initial tensions of 10, 30, 50, and 70 N, respectively). The calcaneus also moved more posteriorly with external rotation as the initial tension increased. The reconstructed graft tension tended to increase as the initial tension increased. Conclusion: Ankle kinematic patterns and laxity after CFL reconstruction tended to become more abnormal as the initial graft tension increased at the time of surgery. Moreover, excessive initial graft tension caused excessive tension on the reconstructed graft. Clinical Relevance: This study indicated the importance of initial graft tension during CFL reconstruction. Overtensioning during CFL reconstruction should be avoided to imitate a normal ankle.

Risk factor analysis of female soccer tournament players

In this study, a 2-dimensional (2-D) video analysis of anterior cruciate ligament injury events from the sagittal and coronal planes was introduced. Using a sagittal analysis, we analyzed the landing action after heading when no injury occurred and checked variables related to anterior cruciate ligament injury. We found that the trunk angle was similar when injury or no injury occurred, and the hip angle and the distance from the center of mass to the base of support (COM_BOS) were smaller in both injured and control participants compared to those reported in previous studies. Future video studies are planned to analyze not only injury but also non-injury events to develop a screening tool for risk factors.

The Use of a 6-DOF Robotic System for the Functional Analysis of Ankle Joint Ligaments

Ankle sprains are common injuries in daily and athletic activities. An epidemiological report indicated that the incidence rate of ankle sprains treated in emergency departments in the USA is more than 2 per 1000 persons a year, and the rate is estimated to be more than double as for ankle sprains in athletic activity [1]. Better understanding of ankle biomechanics is, therefore, important for the improvement of clinical outcome. Many investigators have performed in vitro and in vivo experiments to determine the mechanical roles of ankle structures such as range of motion, contribution of ankle ligaments to joint stability, joint instability due to ligament transection, and so on. In spite of these efforts, tensile forces in ankle ligaments in response to specific loading conditions still remains unclear because of a lack of experimental methodology. Meanwhile, the use of robotic technology for knee joint biomechanics study has been established by Fujie et al [2]. Using the technique, tensile forces in knee cruciate ligaments have been determined by Woo et al [3], Li et al [4], Fujie et al [5], and other groups, while ligament reconstruction technique has been evaluated by many investigators [for example 6–8]. Therefore, the objectives of the present study were to determine the ankle joint instability due to ligament transection and to determine the tensile forces in the anterior tarofibular ligament (ATFL) and calcaneofibular ligament (CFL) in response to anterior-posterior (AP) drawer force to the human cadaveric ankle joints.Copyright

Arthroscopic resection of multiple ossifying tumors in the infrapatellar fat pad

A 49 year-old male visited a nearby clinic five years back with a complaint of pain in the right knee during exercise. Plain radiographs revealed absence of any anomalies. He began to feel a lumpy mass in his right knee two years back. The pain worsened, on imaging, an anomaly was identified in the infrapatellar fat pad of his right knee, and he was subsequently referred to our department where he was hospitalized. On examination, a mass extending on either side of the patellar tendon was identified along with rigid tenderness in that area. The knee’s range of motion was 0degrees-130degrees, and knee flexion was accompanied by pain. The results of blood tests were normal. A plain radiograph of the knee revealed multiple ossifying tumors at a site consistent with the infrapatellar fat pad. T1-weighted MRI exhibited low-signal intensity, while T2-weighted MRI exhibited a mosaic-shaped tumor. We performed arthroscopic surgery to excise the tumor. The patient resumed work shortly after surgery and did not experience any pain during the two year postoperative observation period. The joint’s range of motion improved to the extent that it was comparable with that of the left knee. No recurrence was observed on radiographic examination. In past studies, resection of similar tumors has been performed with an arthrotomy; however, we performed arthroscopic resection on our patient, who demonstrated a quick improvement in symptoms and range of motion after surgery. We believe that arthroscopic surgery is a feasible option to consider while treating such cases.