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Biomedical subjects

K Shirakura

Publications and source records attributed to K Shirakura.

At least 37 records · Page 2Linked to original sources
PubMed1997

Free synovium promotes meniscal healing. Synovium, muscle and synthetic mesh compared in dogs.

We studied the effect of free synovium on the healing of tears in the avascular portion of the menisci in dogs. A longitudinal incision was made in the medial meniscus. In 35 dogs, a free graft of synovium was inserted into the tear and sutured. In 10 dogs, a free graft of quadriceps muscle was used. In 10 dogs, a Dacron mesh was inserted. In the contralateral knee, the tear was sutured without implantation as a control. 2, 4, 6, 8, and 12 weeks after the operation, the menisci were dissected. 11 of the 35 with free synovium were healed. The menisci with muscle grafts, those with Dacron mesh and those in the control group did not heal. Histology showed that tears were repaired with fibrous tissue. Microangiography showed that capillaries grew from the periphery, but they did not reach the tear.

Animals↗
PubMed1996

Separated ossicles of the lateral malleolus.

Sixty ankles of 59 patients with symptomatic ossicles of the lateral malleolus were studied. All patients underwent clinical and radiographic examinations. Stress arthrography was performed on 58, arthroscopy on 48, operative treatment on 52, and histologic examination on 23. The ossicles were classified into 3 sizes (small, medium, and large) and 2 levels (A and B) by location. The relationship between the ossicle and fibular tip was classified into 3 grades according to arthrography results (Grade 1, little inflow [< 1 mm] of the contrast medium; Grade 2, an apparent space [1-2 mm]; Grade 3, a large gap [> 2 mm]) and to operative and arthroscopic findings (Type A, a fibrous union; Type B, a partial continuity; Type C, a lax thin scar tissue; Type D, no continuity). There were significant differences in talar tilt angles on stress radiography between the 3 grades. Chronic symptoms had a tendency to increase from Grade 1 to Grade 3 and from Type A to Type C or D, with instability occurring more than pain. The size and level did not correlate with instability. Acute or chronic inversion forces may act on the connection between the ossicle and fibular tip, and damage to this structure may cause symptoms.

Adolescent↗
PubMed1995

Untreated acute anterior cruciate ligament tears of the knee: progression and the influence of associated injuries.

Arthroscopy was performed on 53 consecutive patients with acutely torn ACL within two weeks after the initial injury. Arthrography was performed on 42 of the 53 patients prior to arthroscopy. Four Segond's fractures, twenty-six meniscus tears (eight medial, eighteen lateral) and nineteen medial collateral ligament (MCL) ruptures were revealed. One medial meniscectomy was performed under arthroscopy, and ten MCL tears were repaired in the acute phase. No surgical procedure was done on the torn ACL, but three excisions of ACL stubs were performed due to a restriction of full extension. The patients were re-examined clinically and radiographically after a period of from 3 years 7 months to 11 years 1 month, averaging 6 years 2 months. Four late meniscectomies were performed on the medial menisci in the chronic phase. Anterior translations of the tibia and knee rating scores of the patients with MCL tears and with Segond's fractures did not differ from those of the others. Anterior translations of the tibia in patients with medial meniscectomies increased (P < 0.05), and their functional scores significantly decreased (P < 0.01) more than those of the other patients. Patients with repaired MCL tears showed significantly higher functional scores than those of the patients with unrepaired MCL ruptures (P < 0.05).

Acute Disease↗
PubMed1995

Meniscal repair using a flap of synovium. An experimental study in the dog.

The healing process of longitudinal lesions in the avascular region of the meniscus was investigated in 42 menisci from 21 dogs. A longitudinal incision was made in the avascular portion of the medial menisci of 21 dogs. In one knee, a flap of synovium was sutured into the wound, and in the other, the wound was sutured as a control. Animals were killed after 1 to 12 weeks, and the menisci were removed and examined by gross inspection, light microscopy, and microangiography. In the control knees, no healing had occurred. In 19 of 21 knees in which a synovial pedicle was used, the suture site did not open at any of the postoperative weeks. The longitudinal lesion was repaired with fibrovascular tissue at 6 weeks, and the vessels over the femoral surface of the menisci and an inner portion of the menisci had reached the suture site. The healing of meniscal lesion occurred due to the use of the vascularized synovial pedicle flap and the neovascularization from the parameniscal area.

Animals↗
PubMed1995

Second look arthroscopy after meniscal repair. Factors affecting the healing rate.

Second look arthroscopy was performed on 46 of 137 consecutive patients who underwent arthroscopic meniscal repair. All tears were of the vertical type. Thirty-two tears were located in avascularized areas. Thirty-one patients had associated anterior cruciate ligament insufficiencies. Anterior cruciate ligament reconstructions were performed simultaneously on 26 patients. The double-needle cannula method was used in all the patients. An additional transplantation of a vascularized synovial pedicle flap to the suture site was performed on 7 tears in avascularized areas. Second look arthroscopy showed no healing in 8 patients and healing in 38. Four of the 8 unhealed tears were located in avascularized areas, and 4 had unreconstructed anterior cruciate ligament injuries respectively. All 7 patients with synovial pedicle flaps showed healing. All patients with anterior cruciate ligament reconstructions showed healing, and the healing rate was significantly higher than that of the other patients (p < 0.005). Patients with anterior cruciate ligament insufficiencies showed a significantly lower healing rate than the others (p < 0.005). In patients with tears in avascularized areas, the conventional meniscal repairs showed a lower healing rate than did the repairs with a synovial pedicle transplantation or an anterior cruciate ligament reconstruction (p < 0.005). These results suggest that the most important factors influencing meniscal healing are the presence of anterior cruciate ligament tears, ligamentous reconstruction, and vascularity of the tear site.

Adolescent↗
PubMed1995

Axial parameters affecting lower limb alignment after high tibial osteotomy.

Lower limb alignment of 46 knees treated with high tibial osteotomy was studied to find a method for determining the precise correction angle. The femorotibial angle was divided into several axial alignment parameters. Before the operations, the femorotibial angle correlated with the tilting angle of the femoral shaft toward the horizontal (femoral shaft-horizontal angle) and that of the tibial shaft toward the horizontal (tibial shaft-horizontal angle). After the operations, the femorotibial angle correlated with the tibial shaft-horizontal angle, but not with the femoral shaft-horizontal angle. The postoperative femoral shaft-horizontal angle tends to be constant regardless of the degree of valgus. In preoperative varus knees, the varus deformity increases the degree of shift of the femoral and tibial shaft toward the varus direction. In postoperative valgus knees, the more valgus the knee the more the tibial shaft shifted toward the valgus direction, which was not true for the femoral shaft. The femorotibial angle was influenced more by the tibial axial alignment in the postoperative valgus knee. The slope of the distal femoral articular surface influenced the tilt of tibial articular surface toward the horizontal which, in turn, influenced the tibial shaft-horizontal angle. The authors recommend relying on the tibial axial alignment parameter to determine the amount of correction. The slope of the distal femoral articular surface should be considered in preoperative planning.

Adult↗
PubMed1995

The natural history of untreated anterior cruciate tears in recreational athletes.

A followup study was performed to elucidate the natural course of acutely torn anterior cruciate ligaments in recreational athletes. Fifty-six consecutive patients had arthroscopy within 2 weeks of their initial injuries; however, no surgery was done on the torn anterior cruciate ligament. Twenty anterior cruciate ligament and medial collateral ligament combined ruptures occurred. Patient ages ranged from 14 to 50 years old (mean, 28.9 years). Followup periods ranged from 2 to 10 years (mean, 5 years 6 months). Through examination with the KT-1000 arthrometer, side-to-side differences of anterior translation of the tibia of > or = 3 mm in 72% patients at reexamination were seen. Eight of 46 patients had mild osteoarthritic changes of Grade 1 visible on radiographs, but only 1 patient reported knee trouble. Nine patients had repeat injuries, 3 of whom had late reconstructions and 4 late meniscectomies. Functional scores averaged 95 +/- 6.5 points. Activity scores averaged 4.8 +/- 1.6 points. Operative management for the medial structure did not improve the stability better than nonoperative management. Anterior translation and functional scores of patients with medial meniscectomies showed significant differences from those of other patients. Anterior cruciate ligament reconstruction for recreational athletes should be considered when the patients have reparable meniscal tears, and meniscal repairs should be performed simultaneously.

Adolescent↗
PubMed1993

Scapulohumeral reflex (Shimizu). Its clinical significance and testing maneuver.

Searching for a muscle stretch reflex that is innervated by the high cervical cord, the authors discovered the scapulohumeral reflex (Shimizu)--SHR (Shimizu). The testing maneuver, localization of the reflex center, its clinical significance, and the designation of the SHR (Shimizu) are dealt with in this report. The SHR is elicited by tapping the tip of the spine of the scapula and acromion in a caudal direction. The SHR is classified as hyperactive only when an elevation of the scapula or an abduction of the humerus have been clearly defined after tapping at these points. Two hundred twenty-five patients with cervical spine disorders, 90 normal individuals, and 17 patients with cerebrovascular strokes were examined. The incidence of hyperactive SHR was highest among several neurologic abnormalities in spastic cases with craniovertebral or high cervical lesions, and all cases with hyperactive SHR in the cervical spine disorder group exhibited neural compressive factors at the high cervical region. The major muscles participating in the SHR are considered to be the upper portion of the trapezius, the levator scapulae, and the deltoid. According to the anatomic level of compressive factors and the postoperative course of the activity in hyperactive SHR cases, the reflex center of the SHR is clinically presumed to be located between the posterior arch of C1 and the caudal edge of the C3 body. Hyperactive SHR provides useful information about dysfunctions of the upper motor neurons cranial to the C3 vertebral body level.

Accessory Nerve↗
PubMed1992

Anatomy and pathophysiology of the popliteal tendon area in the lateral meniscus: 1. Arthroscopic and anatomical investigation.

An arthroscopic and anatomical investigation was performed to define the abnormal conditions of the popliteal tendon area in a lateral meniscus. Arthroscopic findings for 100 patients and anatomical observations of 10 amputated knees were analyzed. Five of the 10 dissected menisci were also examined histologically. Menisco-tibial coronary ligaments were classified into two types, as follows: type I--a coronary ligament covering an entire popliteal tendon beneath the meniscus; type II--a popliteal tendon visible beneath the meniscus through defects of the coronary ligament. Twenty-one of 100 cases were classified as type I, and 79 were classified as type II. Three of the 10 anatomical dissections were type I, and the remaining 7 were type II. Menisci in which the type I coronary ligaments were thought to be torn and menisci with type II coronary ligaments showed a rather marked mobility, but no conclusion could be reached.

Adolescent↗
PubMed1992

Anatomy and pathophysiology of the popliteal tendon area in the lateral meniscus: 2. Clinical investigation.

Treatment of abnormal mobility of the popliteal tendon area of the lateral meniscus is described. Twenty-seven patients who exhibited an abnormally mobile posterior segment with no obvious ruptures in the lateral meniscus were directly examined by us after an average of 4 years and 3 months from the time of the arthroscopic procedure. The main complaints associated with this condition before the surgery were pain and locking during deep knee flexions. The patients were divided into three groups according to surgical method: partial meniscectomy, subtotal meniscectomy, or meniscal repair. The subtotal meniscectomy and repair groups showed significantly higher scores than the partial meniscectomy group. A locking phenomenon recurred in one case of the meniscal repair group. In this case, the menisco-femoral coronary ligament posterior to the popliteal tunnel could not be sutured.

Adolescent↗
PubMed1991

Dissolution of solid dosage form. II. Equations for the dissolution of nondisintegrating tablet under the sink condition.

An equation for dissolution from the whole surface of a nondisintegrating single component tablet under the sink condition was derived. Also, equations for several dissolution manners of the tablet under the sink condition were derived in the postulation of the dominant dissolution rate constant which determines the dissolution manner. The applicability or validity of these equations were examined by the dissolution measurements with nondisintegrating single component tablets. About one-tenth the amount of the amount needed to saturate the solution was used to prepare a tablet, and dissolution measurements were carried out with the tablet whose flat or side surface was masked with an adhesive tape in accordance with the conditions for derivation of equations. Among the derived equations, dissolution from the whole surface of a tablet was expressed by a form similar to the cube root law equation for particles. Hence, a single component tablet compressed by the use of a suitable amount was thought to behave like a single crystal. Also, equations derived for several dissolution manners were thought to be applicable for the dissolution of a nonspherical particle and crystal concerning the crystal's habit and its dissolution property, and the extended applicability was examined by converting the crystal into a simplified or idealized form, i.e., rectangle or plate.

Mathematics↗
PubMed1988

Intraoperative EEG monitoring: (I). Parametric representation of processed EEG during anesthesia.

One of the most common techniques of EEG monitoring during operations is to produce a three dimensional image by displaying the frequency distributions with respect to time as in compressed spectral array (CSA) and density-modulated spectral array (DSA). In order to characterize these images by numerical parameters, we defined two parameters; the percent spectral edge frequency as the frequency at which the one-sided-power sum reaches the designated percentage of the total; and the mean frequency as the power-weighted mean within the interval that includes a dominant spectrum in the frequency distribution. These parameters were superimposed on displays to characterize EEG changes, and they proved to be a very powerful tool to quantitate variations in data among anesthetic techniques and thus efficiently control the depth and duration of anesthesia. We report a number of actual cases.

Adult↗
PubMed1988

Intraoperative EEG monitoring: (II). Similarity analysis using density-modulated t array.

A method of showing the similarity, in other words, defining the difference between a pair of EEG patterns has been developed. By using the student t test on the power spectra at the appropriate frequency intervals, the t values obtained can be used as an indicator of the difference between the spectral patterns with respect to the frequency intervals. This so-called t-profile can be computed on real time basis and the result superimposed in different colors using the apparatus described previously to produce a 3-dimensional picture. We call this picture a density-modulated t array or DTA. Along with CSA and DSA (compressed/density-modulated spectral arrays), it proved to be a very powerful tool in intraoperative EEG monitoring.

Adult↗
PubMed1987

Application of a screening test for depression in the Health Counselling Center.

This paper outlines the process of development and the clinical usefulness of a screening test for depression. First we developed a draft questionnaire consisting of 13 items, each of which had three answers--(1) often, (2) sometimes, (3) none--, with reference to certain kinds of rating scales. After each answer was quantified by the sigma method, each item was statistically analyzed among 75 depressive patients and 250 almost healthy subjects visiting the AMHTS (Automated Multiphasic Health Testing and Services) center. Then 12 items effective for discriminating between the two groups were computed by discriminant analysis to produce depression scores which varied from 0 to almost 100 in proportion to the severity of depression. This questionnaire was applied to all consultees visiting the AMHTS, and revealed that almost 1% of them showed higher scores than the threshold score. Psychiatric interviews with the subjects suspected of depression indicated that all of them were in the transient maladapted state although only ten out of 16 were referred to a psychiatric outpatient clinic for further examination and treatment. The validity of this questionnaire was also confirmed by the fact that 86% of 50 additional depressive patients showed higher scores than the threshold score.

Algorithms↗