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Biomedical subjects

S Omokawa

Publications and source records attributed to S Omokawa.

At least 19 recordsLinked to original sources
PubMed2005

Anatomical consideration of vascularized bone graft transfer from the medial calcaneus to the talus.

To investigate the possibility of use of the calcaneal branches of the posterior tibial artery as the pedicle for the vascularized bone graft to the talus, a detailed anatomical study was carried out on 30 fresh cadaver feet. Although there are several branches from the posterior tibial artery to the calcaneus, the largest posterior branch was defined as the main calcaneal branch. We recognized frequently a large branch nourishing the superior part of the calcaneus and named it the superior calcaneal branch. Twenty feet had the superior calcaneal branches. Pedicled bone grafts using the superior calcaneal branch to the postero-medial portion of the talar body were possible in 18 of 20 feet. Pedicled bone grafts using the main calcaneal branches were possible in 9 of 12 feet in which the superior calcaneal branches were not available. Finally, vascularized bone grafts were judged to be feasible in 27 feet (90%).

Adult↗
PubMed2005

The anatomical basis for reverse first to fifth dorsal metacarpal arterial flaps.

This study discusses the anatomical basis for reverse first to fifth dorsal metacarpal arterial flaps. The arterial pattern and size of the first to fifth dorsal metacarpal arteries were examined in 20 fresh cadaver hands. Their connections to the palmar arterial system at the metacarpal head were observed, and the location, number and diameter of skin perforators from each dorsal metacarpal artery were measured. The first to fourth dorsal metacarpal arteries were found in all specimens; the fifth dorsal metacarpal artery was found in 19 of our 20 specimens. The mean diameters of the first to fifth arteries at their bifurcation site were 0.6, 0.8, 0.5, 0.4 and 0.2 mm, respectively. Each artery gave off four to eight skin perforators (diameter: 0.1-0.3 mm) between the metacarpal head and base. The first to third dorsal metacarpal arteries consistently connected to the palmar arterial system, and connections between the fourth and fifth dorsal metacarpal arteries and the palmar system were found in 65% and 40% of specimens.

Cadaver↗
PubMed2001

Current topics on centrifugal plasmapheresis technologies.

In the field of plasmapheresis centrifugal technology has recently focused on the collection of peripheral blood stem cells (PBSCs) for both autologous and allogeneic transplantation in patients with malignancies or hematological diseases and on donor plasmapheresis. PBSC transplantation is rapidly replacing bone marrow transplantation in such patients. Various kinds of apheresis equipment were applied and described for PBSC collection. Comparison among machines is described. Allogeneic PBSCs were collected from healthy normal donors. Specific attention to the dose and administration duration of granulocyte colony-stimulating factor and a careful apheresis procedure should be made for donor safety. In platelet transfusion practice, a platelet concentrate product derived plateletpheresis from a single donor is preferable to minimize and to prevent adverse transfusion reactions. The status of platelet collection and its efficacy by various kinds of plateletpheresis equipment are discussed. The Amicus and CCS might be preferable plateletpheresis machines because of their collection efficiencies and wider indication for donors. With the limited number of donors, it is essential that plateletpheresis should be more effectively performed and managed by each regional blood center. The status of plasma and red cell collection by apheresis technologies is described also briefly.

Centrifugation↗
PubMed2001

Status of platelet collection and platelet transfusion.

Platelet product derived from single donor plateletpheresis is required to reduce the risks of adverse reactions by blood transfusion. The objectives of this study are to evaluate the status of platelet collection and its efficacy by various kinds of plateletpheresis equipment and to assess the achievement of platelet transfusion by platelet product derived from a single donor. Since the blood centers have introduced some kinds of efficient plateletpheresis equipment, large units of platelet products have been supplied mainly for the patients. Amicus and CCS might be preferable plateletpheresis machines because of their collection efficiencies and wider indication for donors. The average number of donors of platelet product per patient has recently reached nearly 1.0, and around 90% of patients have received platelet product derived from a single donor in the recent several years. However, platelet transfusion derived from a single donor has not yet been completely achieved. Each regional blood center should seriously consider the efficacy of each plateletpheresis equipment and arrange the equipment to collect platelets more effectively to achieve platelet transfusion from a single donor.

Blood Platelets↗
PubMed2001

Innervated radial thenar flap combined with radial forearm flap transfer for thumb reconstruction.

A radial thenar flap combined with radial forearm flap was used for the reconstruction of the ipsilateral thumb in four patients. Vascular supply of the combined flap was based on the radial artery and extending the vascular pedicle to the superficial palmar branch of the radial artery. The flap was sensated by the palmar branch of the superficial radial nerve. The size of the flap averaged 15 x 5 cm and the innervated region of the thenar eminence was an area approximately 5 x 3 cm located over the proximal parts of the abductor pollicis brevis and opponens pollicis muscles. The flap was transferred as a free flap in three patients and as an advancement flap in one patient. The flaps survived completely without complications. Satisfactory restoration of sensation was achieved in the flap area, as shown by 6 mm of average moving two-point discrimination. This combined flap may be a feasible reconstructive option for large palmar defects of the fingers such as degloving injuries.

Adult↗
PubMed2001

Anatomical consideration of reverse-flow island flap transfers from the midpalm for finger reconstruction.

Primary soft-tissue coverage for large palmar defects of the fingers is a difficult problem for cases in which homodigital or heterodigital flaps cannot be used. The aim of this study was to explore the vascular and neural anatomy of the midpalmar area to assess the possibility of reverse island flaps from this area. In 24 cadaver hands perfused with a silicone compound, the arterial pattern of the superficial palmar arch and common palmar digital artery was examined. The cutaneous perforating arteries and nerve branches supplying the midpalmar area were dissected, and the number, location, and arterial diameter of these branches were measured. In six other specimens, the common palmar digital artery was injected to determine the skin territory supplied by the artery. The superficial palmar arch contained the three common palmar digital arteries and its terminal branch coursed along the radial margin of the index metacarpus. This terminal branch had three to six cutaneous perforators (diameter range, 0.1 to 0.5 mm) and supplied the radial aspect of the midpalmar area located over the ulnar half of the adductor pollicis muscles. The midpalmar area was divided into two regions-the proximal and distal-according to the vascular distributions. The proximal region contained dense aponeurosis and thin subcutaneous tissue, and the cutaneous perforators were rather sparse (between three and nine) and had a small diameter (0.1 to 0.3 mm). The distal region, which had loose aponeurosis and abundant subcutaneous tissue, had a rich vascular supply from the common and proper digital artery. Perforating arteries of this region coursed frequently in an oblique fashion and the number of perforators (between eight and 15) and their arterial diameters (diameter range, 0.1 to 0.5 mm) were higher than those of the proximal region. The area of skin perfused by the common palmar digital artery was 5 x 3 cm at the distal midpalmar region. There were three to five cutaneous nerve branches from the palmar digital nerve supplying the midpalmar area. From this study, two different reverse flaps were proposed. First, a 5 x 2 cm flap from the distal midpalmar region was elevated on the basis of the common and proper palmar digital artery. Measurement of the rotation arc revealed that the pivot point of this flap was located at the proximal interphalangeal joint level and could cover the finger pulp of the digits. The second flap candidate was that from the radial aspect of the midpalm, which was supplied by the terminal branch of the superficial palmar arch. In studies with cadaver hands, connection of this artery with the deep arterial system enabled this flap to reach the thumb pulp. These flaps may be a useful reconstruction option for significant palmar soft-tissue loss of the fingers.

Adult↗
PubMed2000

Development of a rapid blood transfusion system with the capability of blood purification.

Blood is usually irradiated by x-ray to prevent graft-versus-host-disease. However, plasma potassium levels of irradiated blood are rapidly increased during preservation in irradiated blood. The objectives of this study were to develop a rapid blood transfusion system for which irradiated blood can be used and to evaluate the capability of blood purification of the system. Packed red blood cells (RBC) were irradiated (15 Gy x-ray) at 21 days and preserved until 42 days after collection. A blood mixture of RBC and plasma was perfused through a dialyzer at 25, 50, 100, and 200 ml/min. Dialysate was perfused at 100, 100, 500, and 500 ml/min, respectively. Preperfusion levels of sodium, 121; potassium, 35; and chlorine, 76 mEq/L were changed to sodium, 144 to 146; potassium 2.5 to 3.0; and chlorine, 105 to 110 mEq/L, which were comparable with the levels in dialysate after perfusion for 25, 50, and 100 ml/min perfusion groups. For the 200 ml/min perfusion group, potassium was 5.3 mEq/L after perfusion which was slightly higher than other groups, but 84% of the potassium was removed by the system. Citrate levels were significantly decreased to 3.4, 28, 31, and 81 mg/dl for the 25, 50, 100, and 200 ml/min groups, respectively, after perfusions. The rapid transfusion system composed of the dialyzer and the blood pumps was effective in the removal of potassium and in the normalization of electrolytes. Irradiated blood with high levels of potassium can be safely and effectively used for this system in cases requiring massive rapid blood transfusion.

Blood Preservation↗
PubMed2000

Trapeziometacarpal joint instability affects the moment arms of thumb motor tendons.

This study measured the changes in moment arm length of thumb motor tendons after simulated ligamentous instability and subsequent reconstruction of the trapeziometacarpal joint. Excursions of thumb motor tendons were measured simultaneously with the trapeziometacarpal joint angulation during flexion to extension and abduction to adduction motion. Tendon moment arms were calculated based on joint and tendon displacement techniques in the intact joint, after sequential sectionings of the capsuloligamentous restraints, and after the reconstruction procedure of Eaton and Littler. The results showed that moment arms of the abductor pollicis longus and extensor pollicis brevis tendons increased significantly as compared with those for normal joints during flexion to extension motion after sectioning the palmar capsuloligamentous components. After the ulnopalmar structures were cut, the moment arm of the extensor pollicis longus tendon had a statistically significant increase during abduction to adduction motion, and those of the extensor and flexor pollicis longus tendons decreased significantly during flexion to extension motion. Changed moment arms were restored to a normal level after the ligamentous reconstruction. These results indicate that ligamentous disruptions alter the mechanical balance of thumb motor tendons, which may contribute to joint deformities observed in trapeziometacarpal joint arthritis. Restoring joint stability is important to correct mechanical imbalance of the tendons.

Aged↗
PubMed2000

A reverse ulnar hypothenar flap for finger reconstruction.

A reverse-flow island flap from the hypothenar eminence of the hand was applied in 11 patients to treat palmar skin defects, amputation injuries, or flexion contractures of the little finger. There were three female and eight male patients, and their ages at the time of surgery averaged 46 years. A 3 x 1.5 to 5 X 2 cm fasciocutaneous flap from the ulnar aspect of the hypothenar eminence, which was located over the abductor digiti minimi muscle, was designed and transferred in a retrograde fashion to cover the skin and soft-tissue defects of the little finger. The flap was based on the ulnar palmar digital artery of the little finger and in three patients was sensated by the dorsal branch of the ulnar nerve or by branches of the ulnar palmar digital nerve of the little finger. Follow-up periods averaged 42 months. The postoperative course was uneventful for all patients, and all of the flaps survived without complications. The donor site was closed primarily in all cases, and no patient complained of significant donor-site problems. Satisfactory sensory reinnervation was achieved in patients who underwent sensory flap transfer, as indicated by 5 mm of moving two-point discrimination. A reverse island flap from the hypothenar eminence is easily elevated, contains durable fasciocutaneous structures, and has a good color and texture match to the finger pulp. This flap is a good alternative for reconstruction of palmar skin and soft-tissue defects of the little finger.

Adult↗
PubMed1999

Evaluation of efficacy in platelet collection by the Haemonetics Component Collection System.

Platelet concentrate product derived from plateletpheresis from a single donor is preferable in terms of reducing the risks of adverse reactions in platelet transfusion. This study evaluated the status of platelet transfusion and the efficacy and safety of plateletpheresis machines. The average number of donors of platelet product per patient has been decreasing and recently reached nearly 1.0; however, some patients still receive multiple random donor platelet products. Platelet collection efficacy was comparable between the Haemonetics Component Collection System (CCS) and the Multi Component System (Multi). However, the CCS has been shown to be effective in terms of processed blood volume and procedure time, especially in donors with lower hematocrits. These results suggest that the CCS may be preferable and safer for donors with lower hematocrits and lighter body weights. Blood centers should collect platelets more effectively to achieve platelet transfusion with the use of platelets derived from a single donor using effective equipment.

Blood Donors↗
PubMed1999

Biomechanical evaluation of wrist motor tendons after fractures of the distal radius.

We conducted a biomechanical study of changes in parameters of wrist motor tendons in fractures of the distal radius in 7 cadaveric extremities. Extra-articular distal radius fractures were simulated by distal radius osteotomy and fracture angulation was maintained by external fixators. Eight positions of the distal radius fractures were studied: dorsal angulation of 10 degrees, 20 degrees, 30 degrees, and 40 degrees and radial angulation of 5 degrees, 10 degrees, 15 degrees, and 20 degrees. Dorsal and radial angulation of the fractures were measured with respect to the shaft of the radius. Excursions of 5 principal wrist motor tendons extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris were recorded simultaneously with wrist joint angulation using a computer-assisted recording system. Data were collected from intact wrists and from wrists with fractures at each of 8 positions of angulation during wrist flexion and extension and radical and ulnar deviation. Moment arm of the wrist motor tendons was derived from tendon excursion and joint angulation. The results demonstrated that excursions and moment arms of principal wrist motor tendons are significantly affected by dorsal and radial angulation of distal radius fractures. Amplitude of changes in moment arms increased as the deformities became more severe. Statistical analysis revealed that dorsal angulation of 10 degrees or more significantly affected moment arms of all the prime wrist motors. Dorsal angulation of 30 degrees or 40 degrees changed the moment arms greatly. Radial angulation of 5 degrees did not affect moment arms of the tendons and angulation over 10 degrees had a statistically significant effect on the tendons. We conclude that deformities of distal radius fractures have a significant influence on the biomechanics of the wrist motors.

Aged↗
PubMed1997

Biomechanical changes of the wrist flexor and extensor tendons following loss of scaphoid integrity.

Loss of integrity of the scaphoid may change the motion center of the entire carpus, and deformities from scaphoid fractures may alter the location of motor tendons of the wrist, thus altering their biomechanics. The goal of this study was to clarify biomechanical changes in these tendons following loss of scaphoid integrity. Excursions and moment arms of the principal flexor and extensor tendons of the wrist were investigated in seven cadaveric upper extremities in intact wrists after simulation of scaphoid waist fracture and after removal of the proximal scaphoid. Excursions of the flexor carpi radialis and ulnaris, extensor carpi radialis longus and brevis, and extensor carpi ulnaris tendons were measured with rotary potentiometers during wrist flexion-extension and radioulnar deviation. Simultaneously, wrist joint angulation was recorded. Moment arms of the tendons were derived from tendon excursions and joint motion. After scaphoid fracture, the moment arms of the flexor carpi radialis and extensor carpi ulnaris tendons increased significantly during wrist flexion-extension, whereas the moment arms of the extensor carpi radialis longus and brevis tendons decreased significantly. After proximal scaphoid excision, the moment arms of the extensor carpi radialis longus and brevis tendons again decreased significantly during wrist flexion-extension. The moment arms of the flexor carpi radialis and extensor carpi radialis brevis tendons increased significantly during radioulnar deviation, whereas those of the wrist motors on the ulnar side decreased. These findings indicate the importance of the integrity of the scaphoid in maintaining normal biomechanics of motor tendons of the wrist. An increase in the moment arm of the radial wrist flexor along with a decrease in moment arms of the radial extensors constitutes as etiology for persistent angulation of the scaphoid and the humpback deformity. In addition, disturbing the biomechanics of the wrist motor tendons predisposes the carpal joints to abnormal loading, potentially contributing to the development of carpal joint degeneration.

Aged↗
PubMed1997

Vascular and neural anatomy of the thenar area of the hand: its surgical applications.

Thirty fresh cadaver hands were injected with a silicone rubber compound (Microfil) and dissected to examine the vascular and neural supplies of the thenar area. In 10 specimens, a selective injection technique was used to determine the extent of skin territory nourished by the superficial palmar branch of the radial artery. The purpose of this study was to clarify the anatomic basis for clinical applications of vascularized free- or island-flap transfers from the thenar area. The superficial palmar branch of the radial artery was found in all hands; the average diameter of the branch measured at its bifurcation site was 1.4 mm (0.8 to 3.0 mm). The constant area nourished by the superficial palmar branch was an area approximately 4 x 3 cm located over the proximal parts of the abductor pollicis brevis and opponens pollicis muscles. These results indicate that a fasciocutaneous flap from the radial thenar region can be raised based on the superficial palmar branch and consistently transferred as a free flap. In 63 percent of the hands dissected, the superficial palmar branch was connected to other arteries in the palm, suggesting that the flap can be transferred as a reverse-pedicle island flap in such hands. Innervation of the flap was provided chiefly by a branch of the superficial radial nerve. The radial aspect of the thenar eminence can provide a new and useful donor source for an innervated and vascularized free- or island-flap transfer for reconstruction of various skin defects of the volar side of the fingers.

Arteries↗
PubMed1996

A long-term study of the donor-site ankle after vascularized fibula grafts in children.

We reviewed the long-term course of the donor-site ankle after vascularized fibula grafts in 13 children. The preventive and therapeutic effects of the tibio-fibular metaphyseal synostosis (T-F synostosis) against valgus ankle deformity, which is one of the postoperative donor-site problems, were evaluated based on three radiologic and clinical parameters. Thirteen patients were divided into two groups: patients with or without simultaneous T-F synostosis when the fibula was taken. Three patients underwent T-F synostosis secondarily after the development of the valgus deformity. Follow-up periods averaged 12.4 years. In the patients with primary T-F synostosis, valgus deformity was only observed in one case. No functional disorder of the ankle joints was observed after T-F synostosis. In the patients without T-F synostosis, all the patients younger than 8 years old showed valgus deformity, in which the tilting angle averaged 6.3 degrees. In the three patients who underwent T-F synostosis secondarily, the tilting angle normalized in cases in which the fixation was performed when the lateral wedging was in a mild stage. There was a statistically significant difference in valgus tilt angle between the two groups (with or without T-F synostosis).

Adolescent↗
PubMed1996

Anatomical basis for a fasciocutaneous flap from the hypothenar eminence of the hand.

Thirty-two fresh cadaver hands were perfused with a silicone rubber compound (Microfil) and dissected to explore the vascular and neural anatomy of the hypothenar eminence, in order to assess the possibility for free or pedicled island flaps from this area. In five specimens Microfil was selectively injected into the ulnar palmar digital artery of the little finger to determine the skin territory nourished by this artery. The hypothenar eminence was divided into three territories according to the type of nutrient artery supplying each territory. Among the three territories, the distal half of the ulnar aspect of the hypothenar eminence (approximately 3 x 2 cm), located over the abductor and flexor digiti minimi muscles, had a constant vascular and neural supply from the ulnar palmar digital artery of the little finger and the dorsal or palmar cutaneous branch of the ulnar nerve. This fasciocutaneous area provides a new and feasible donor site for free or pedicled island skin flaps to repair palmar skin defects of the fingers.

Aged↗
PubMed1996

Innervated radial thenar flap for sensory reconstruction of fingers.

A radial thenar flap, which is supplied by the superficial palmar branch of the radial artery and innervated by the superficial branch of the radial nerve, was used in four patients for sensory reconstruction of the fingers. Two patients had degloving injuries of the hand and two had amputation injuries of the thumb. Three of the cases underwent free-flap transfers, and one case underwent a reverse-flow island flap. The size of these flaps was about 3 x 5 cm except in one case, where a 15 x 5 cm flap combined with a radial forearm flap was used. Sensory reinnervation was excellent and donor site morbidity was minimal in all four cases. An innervated radial thenar flap from the ipsilateral hand offers an alternative choice to reconstruct large palmar defects of the fingers.

Adolescent↗