Toru Fukubayashi

The contact area and pressure distribution pattern of the knee. A study of normal and osteoarthrotic knee joints.

Seven knees were studied to determine the contact area and pressure distribution of the tibiofemoral joint, under various loads and at 0 degrees flexion, using the casting method and special sensor sheets. At a load of 1000N (Newton) the contact area of the knee was 11.5 x 10(2) mm2 with menisci and 5.2 x 10(2) mm2 without menisci, and the menisci occupied 70% of the total contact area. Peak pressure at 1000N was 3MPa (Mega Pascal) with the menisci and 6MPa without them. The high pressure areas were located on the lateral meniscus as well as on the uncovered part of the articular cartilage of the lateral compartment, and on the uncovered cartilage in the medial compartment. After removal of the menisci the contact area decreased to below one half that of the intact knee and the contact pressure considerably increased. These facts imply that the menisci have load bearing and load spreading functions. The contact areas were also measured in two osteoarthrotic knees and they were significantly larger than those in normal knees. In these arthrotic knees the menisci seemed to play a less significant role in transmission of weight than in the normal knees.

Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement

The incidence of anterior cruciate ligament (ACL) injury remains high in young athletes. Because female athletes have a much higher incidence of ACL injuries in sports such as basketball and team handball than male athletes, the IOC Medical Commission invited a multidisciplinary group of ACL expert clinicians and scientists to (1) review current evidence including data from the new Scandinavian ACL registries; (2) critically evaluate high-quality studies of injury mechanics; (3) consider the key elements of successful prevention programmes; (4) summarise clinical management including surgery and conservative management; and (5) identify areas for further research. Risk factors for female athletes suffering ACL injury include: (1) being in the preovulatory phase of the menstrual cycle compared with the postovulatory phase; (2) having decreased intercondylar notch width on plain radiography; and (3) developing increased knee abduction moment (a valgus intersegmental torque) during impact on landing. Well-designed injury prevention programmes reduce the risk of ACL for athletes, particularly women. These programmes attempt to alter dynamic loading of the tibiofemoral joint through neuromuscular and proprioceptive training. They emphasise proper landing and cutting techniques. This includes landing softly on the forefoot and rolling back to the rearfoot, engaging knee and hip flexion and, where possible, landing on two feet. Players are trained to avoid excessive dynamic valgus of the knee and to focus on the “knee over toe position” when cutting.

Load-bearing mode of the knee joint: physical behavior of the knee joint with or without menisci.

The load-bearing mode of the knee joint and the load-carrying capacity of the menisci were investigated by a load-deflection and load-contact study using stresses of as much as 3 times body weight on 14 freshly amputated knee specimens. A flection angle of 0 degrees was used. The average deflection and the average size of the contact area of the intact knees were 1.04 x 10(-1) cm and 14.1 cm2 respectively when the knees were loaded to 1,500 N. The elastic modulus of the entire joint was 2.7 x 10(2) MPa over the load of 1,500 N. At first, the knee joint was not congruous at a low load under about 500 N; the joint contacts both menisci in conjunction with some part of the exposed cartilage. However, the joint became markedly congruous at higher loads, around 1,000 N. The joint was in contact with the menisci and the exposed cartilage, and as more load was applied, the areas of contact widened to the peripheral areas of both the compartments. After menisci were removed, the deflection increased. The size of the contact areas decreased significantly by a third to a half. Consequently, the average stress increased 2 to 3 times that of the intact knee. The elastic modulus was increased over 2 fold after menisci were removed. The results of the energy study indicate that the menisci gave more elastic stability to the joint. After the menisci were removed, more energy was dissipated during cyclic loading. Thus, the menisci provide surface compliance and serve to transmit stresses across the wider areas to the periphery, and, therefore, help to avoid stress concentration both in the articular cartilage and in the subchondral bone, especially under high loads over 1,000 N.

Load-bearing pattern of the ankle joint - Contact Area and Pressure Distribution

SummaryThe contact area of eight human talocrural joints was measured. After preparation, the talocrural joint was set into the compression machine. Under loading the casting was made by silicon rubber and the pressure distribution was measured by pressure sensor sheet. The contact area was localized at anterior and lateral parts. Under 1,500 N loading, the contact area was 522 mm2 and the maximum pressure was 9.9 MPa. Slight diastasis caused a decrease of the contact area and an increase of pressure.ZusammenfassungAn acht menschlichen oberen Sprunggelenken wurde der Gelenkkontakt analysiert. Nach der Vorbereitung wurde das obere Sprunggelenk in eine Kompressionsmaschine eingespannt. Unter beibehaltener Belastung wurde eine Gußform aus einer Gießmasse hergestellt and auch die Verteilung des Druckes mit einem drucksensitiven Papier vermessen.Die Gelenkkontaktfläche auf der Talusrolle liegt im ventrolateralen Bereich. Unter 1500 N Kompression ist der Maximumdruck 9.9 MPa and der Flächeninhalt 522 mm2. Eine kleine Diastase des oberen Sprunggelenks bewirkt eine Verringerung der Kontaktfläche und eine Vermehrung des Druckes.

Mechanism of quadriceps femoris muscle weakness in patients with anterior cruciate ligament reconstruction

The purpose of this study was to investigate gamma loop function in the quadriceps femoris muscle in patients who with less than 6 month‐history of anterior cruciate ligament (ACL) reconstruction. For this purpose, we compared the response to vibration stimulation in 10 patients with ACL repair and 12 normal healthy subjects, by measuring the maximal voluntary isometric contraction (MVC) and integrated electromyograms (I‐EMG) of the quadriceps muscles. Pre‐vibration data were obtained from each subject by measuring the MVC of the knee extension and the I‐EMG from the vastus medialis, vastus lateralis, and rectus femoris muscles. Vibration stimulation was applied to the infrapatellar tendons, followed immediately by repeating the MVC and I‐EMG recording. Prolonged vibration resulted in a significant decrease of both MVC and I‐EMG in the control group. In contrast, the same stimulus failed to elicit changes in ACL‐repair group. Our results suggest the presence of abnormal gamma loop function in the quadriceps femoris muscle of patients with ACL repair, which may explain the muscle weakness often described in such patients.

Evaluation of human muscle hardness after dynamic exercise with ultrasound real-time tissue elastography: a feasibility study.

AIM To assess the feasibility of ultrasound real-time tissue elastography (RTE) for measuring exercise-induced changes in muscle hardness and to compare the findings of RTE with those of a tissue hardness meter for semi-quantitative assessment of the hardness of exercised muscles. MATERIALS AND METHODS Nine male participants performed an arm-curl exercise. RTE measurements were performed by manually applying repetitive compression with the transducer on the scan position before exercise, immediately after exercise, and at 30 min after exercise; strain ratios between muscle and a reference material (hydrogel) were calculated (muscle strain/material strain). A tissue hardness meter was also used to evaluate muscle hardness. The intraclass correlation coefficients (ICCs) for the three repeated measurements at each measurement time were calculated to evaluate the intra-observer reproducibility of each technique. RESULTS Immediately after exercise, the strain ratio and the value obtained using the tissue hardness meter significantly decreased (from 1.65 to 1.35) and increased (from 51.8 to 54.3), respectively. Both parameters returned to their pre-exercise value 30 min after exercise. The ICCs of the RTE (and the ICCs of the muscle hardness meter) were 0.971 (0.816) before exercise, 0.939 (0.776) immediately after exercise, and 0.959 (0.882) at 30 min after exercise. CONCLUSION Similar to the muscle hardness meter, RTE revealed the exercise-induced changes of muscle hardness semi-quantitatively. The intra-observer reproducibility of RTE was very high at each measurement time. These findings suggest that RTE is a clinically useful technique for assessing hardness of specific exercised muscles.

Acupuncture and responses of immunologic and endocrine markers during competition

INTRODUCTION Acupuncture is used to modulate the physical well-being of athletes in Asian countries. However, there is little information on the immediate effects of acupuncture treatment on physiological or psychological responses to exercise. PURPOSE The purpose of this study was to examine the effect of acupuncture treatment on the physical well-being of elite female soccer players during a competition period. METHODS Subjects were divided into two groups: those who received acupuncture treatment (18.1 +/- 2.3 yr [+/-SD], N = 9) and a control group (17.7 +/- 2.8 yr, N = 12). In the treatment group, acupuncture stimulus was applied at LI 4 (Goukoku), ST 36 (Ashi-sanri) for 20 min, and ST 6 (Kyosya), LU 6 (Ko-sai) points for 15 min 4 h after the game every night during the competition period. The measured parameters included salivary secretory immunoglobulin A (SIgA) level, cortisol level in saliva, subjective rating of physical well-being, and profile of mood states (POMS). RESULTS The following were the main results: 1). Exercise-induced decrease of salivary SIgA and increase of salivary cortisol were inhibited by acupuncture. 2). Acupuncture improved subjective rating of muscle tension and fatigue. 3). The POMS score was modulated by acupuncture. CONCLUSION These results support the effectiveness of acupuncture for physical and mental well-being of athletes.

Gamma loop dysfunction in quadriceps on the contralateral side in patients with ruptured ACL

PURPOSE The aim of our study was to test for any neurophysiological abnormality in the gamma loop in the quadriceps femoris muscle on the uninjured side of patients with unilateral rupture of the anterior cruciate ligament (ACL). METHODS Maximal voluntary contraction of knee extension and integrated electromyography (I-EMG) of the vastus medialis, vastus lateralis, and rectus femoris were measured in the uninjured limb of 13 patients with unilateral ACL rupture and 10 normal subjects, before and after 20-min vibration stimulation applied to the infrapatellar tendon. RESULTS The mean percentage changes of maximal voluntary contraction and I-EMG in quadriceps femoris of the uninjured side of patients with ACL rupture were significantly different from those of the control group. Maximal voluntary contraction and I-EMG after prolonged vibration stimulation did not decrease as much as those of the control group even though the same protocol of vibration stimulation was applied. CONCLUSION The abnormal response to prolonged vibration stimulation could represent abnormal gamma loop in the quadriceps femoris muscle of the uninjured side in patients with ACL rupture since the normal response of maximal voluntary contraction and I-EMG to prolonged vibration stimulation could not be evoked without normal function of the gamma loop.

Relationship between quadriceps femoris muscle volume and muscle torque after anterior cruciate ligament repair.

This study was performed to obtain evidence regarding bilateral hindrance of motor unit (MU) recruitment in the quadriceps femoris (QF) of patients with anterior cruciate ligament (ACL) reconstruction. The subjects included 70 patients who underwent ACL reconstruction and 35 healthy subjects. To identify the muscle torque per unit volume (MTPUV), the peak torque of each velocity of isokinetic performance was divided by muscle volume of the QF measured by a series of cross‐sectional images obtained by magnetic resonance imaging scans. Tests revealed that the mean MTPUV of the uninjured (0.113±0.03 N m/cm3 at 60°/s, 0.081±0.02 N m/cm3 at 180°/s) and injured sides (0.109±0.03 N m/cm3 at 60°/s, 0.079±0.023 N m/cm3 at 180°/s) were significantly lower than those of the control group (0.144±0.05 N m/cm3 at 60°/s, 0.096±0.04 N m/cm3 at 180°/s). Previous studies suggested that MU recruitment in the QF of patients with ACL injury was hindered bilaterally. However, the design of their studies could not provide evidence of bilateral hindrance of MU recruitment in the QF. The results of the present study demonstrated that the MTPUV of both injured and uninjured sides of patients were significantly lower than those of the control group.

Insufficiency of the anterior cruciate ligament - Review of our 118 cases

SummaryRecurrent anterior and internal rotatory subluxation of the tibial plateau is a disabling symptom in patients with insufficiency of the anterior cruciate ligament.Since 1970 we have used the N-test, a special jolt test to detect the characteristic instability. One hundred eighteen cases with anterior-internal rotatory instability of the knee seen at the Kanto Rosai Hospital and the University of Tokyo Hospital and diagnosed by arthroscopy and arthrotomy from 1973 to 1978 were reviewed. Most of the patients were athletes or sportsmen and the injuries commonly occurred in deceleration-injury mechanism and 81% of the cases were associated with meniscal tear.Thirty-two cases were reconstructed by iliotibial tract transfer, twenty of whom had been evaluated from 1–5 years after operation. Postoperatively, giving-way incidents disappeared in eleven, markedly decreased in five, and were unchanged in four patients. The anterior and internal rotatory subluxation of the tibial plateau disappeared or decreased in seventeen and was unchanged in two cases.Some type of defective anterior cruciate ligament was recognized in all our 118 cases and the capsular lesions were considered to play only a secondary role in exhibiting the instability.ZusammenfassungDie periodisch rezidivierende Subluxation des Tibiakopfes nach vorne and innen ist ein charakteristisches Syndrom bei Patienten mit einer Insuffizienz des vorderen Kreuzbandes. Um these Instabilitat ermitteln zu können, verwenden wir seit 1970 den sogenannten “N-Test”, eine von uns entwickelte Variante des “Pivot-shift”-Testes.Im Kanto Rosai Hospital und in der Universitätsklinik Tokio konnten von 1973–1978 118 Fälle mit dieser Instabilitat untersucht and durch Arthroskopie und Arthrotomie diagnostisch gesichert werden. Die Mehrzahl der Patienten waren Sportler, bei denen es bei Decelerationsmechanismen zum Unfall kam. In 81% der Fälle lag gleichzeitig ein Meniskusriß vor. Von 32 durch Verlagerung des Tractus iliotibialis behandelten Patienten werden 20 1–5 Jahre post operationem nachuntersucht. In 11 Fällen verschwand das „giving-way”, das unsichere, plötzliche Nachgeben im Knie vollständig; in 5 Fällen nahm es deutlich ab und nur 4mal blieb es unverändert. In 17 Fällen verschwand oder verringerte sich die Rotationssubluxation nach vorne and innen und nur in 2 Fällen trat keine Veränderung ein. Ein Defekt des vorderen Kreuzbandes wurde in all unseren 118 Fällen festgestellt wohingegen Kapselverletzungen beim Zustandekommen der Instabilität als zweitrangig angesehen werden.