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Dive into the research topics where Kazuhiro Masada is active.

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Featured researches published by Kazuhiro Masada.


Clinical Orthopaedics and Related Research | 1987

Early microsurgical reconstruction in birth palsy.

Hidehiko Kawabata; Kazuhiro Masada; Yuichi Tsuyuguchi; Hideo Kawai; Keiro Ono; Koichi Tada

Most patients with birth palsy can be expected to recover spontaneously. But in some patients the recovery is unsatisfactory and the functional results are disappointing. One possible way to improve the prognosis for such patients is early surgical nerve reconstruction. In six infants, exploration of the brachial plexus was carried out at about six months after delivery, when there were no signs of recovery in shoulder and elbow joint movements. Preoperative metrizamide myelography, computerized tomography with intrathecal metrizamide (CT myelography), and axon reflex test (histamine test) were followed by intraoperative electrophysiologic examinations of root sensory evoked potential (SEP), nerve action potential (NAP), and evoked muscle response (M-response). Microsurgical nerve repair was performed on the basis of intraoperative diagnosis. Metrizamide myelography showed 13% false-positive root avulsion. Reliability of the histamine test was 80%. The intraoperative electro-diagnosis is essential for understanding the actual condition of the brachial plexus lesion and obtaining better results from microsurgical reconstruction in birth palsy. The surgical results, with an average follow-up evaluation of two years and four months, have been encouraging enough to continue this diagnostic and therapeutic program, though its superiority to natural recovery has not yet been clarified.


Journal of Bone and Joint Surgery-british Volume | 1989

Operations for forearm deformity caused by multiple osteochondromas

Kazuhiro Masada; Yuichi Tsuyuguchi; Hideo Kawai; Hidehiko Kawabata; Koichi Noguchi; Keiro Ono

We reviewed 36 cases of forearm deformity caused by multiple osteochondromas in 30 patients and classified them into three types: Type I showed a combination of ulnar shortening and bowing of the radius secondary to osteochondromas of the distal ulna (22 forearms). Type II showed dislocation of the radial head, either with osteochondromas of the proximal radius (Type IIa, two forearms) or secondary to more distal involvement (Type IIb, five forearms). Type III had relative radial shortening due to osteochrondromas at the distal radius (seven forearms). Operations were performed on 16 forearms in 13 patients, with 92% of satisfactory results. For Type I deformity, excision of osteochondromas, immediate ulnar lengthening and corrective osteotomy of the radius are recommended. For Type IIa, excision of the radial head is necessary, and for Type IIb, we advise gradual lengthening of the ulna using an external fixator. Excision of osteochondromas alone gave good results in Type III deformity. Our classification gives a reliable indication of the prognosis and is a guide to the choice of surgical treatment.


Clinical Orthopaedics and Related Research | 1988

Nerve repairs for traumatic brachial plexus palsy with root avulsion

Hideo Kawai; Hidehiko Kawabata; Kazuhiro Masada; Keiro Ono; Koji Yamamoto; Yuichi Tsuyuguchi; Koichi Tada

Thirty-six patients with traumatic brachial plexus lesions and root avulsions were treated surgically between 1972 and 1986 and were followed for more than 24 months (average, 42.6 months). Neurotization of the musculocutaneous nerve with intercostal nerves or the spinal accessory nerve resulted in satisfactory elbow flexion in 21 of the 33 cases (64%). Combined nerve repairs (i.e., intercostal and spinal accessory neurotization of the terminal branch of the brachial plexus in combination with nerve grafts from the upper spinal nerves of the brachial plexus) created a useful function in at least one functional level of the upper limb for 11 of the 15 cases so treated. Nerve repairs resulted in stability of the shoulder and elbow function controllable with a sensible hand for patients with root avulsion injury of the brachial plexus.


Journal of Bone and Joint Surgery, American Volume | 1990

Revision of residual deformities after operations for duplication of the thumb.

Hidehiko Kawabata; Koichi Tada; Kazuhiro Masada; Hideo Kawai; Keiro Ono

We treated thirty-six patients (thirty-eight thumbs) who had residual deformity after ablation of a duplicated thumb. The deformities were classified into three groups: interphalangeal (eight thumbs), metacarpophalangeal (sixteen thumbs), and zigzag (fourteen thumbs). The indication for operation was primarily cosmetic; only eight patients had a functional disability, and that was mild. At the most recent follow-up, the results were rated good except for three fair results in the group that had an interphalangeal deformity, two fair results in the group that had a metacarpophalangeal deformity, and two poor and seven fair results in the group that had a zigzag deformity.


Journal of Pediatric Orthopaedics | 1999

Complications following metatarsal lengthening by callus distraction for brachymetatarsia

Kazuhiro Masada; Satoru Fujita; Takeshi Fuji; Hirofumi Ohno

We performed six metatarsal lengthenings in four patients for brachymetatarsia of the fourth toe by callus distraction from 1991 to 1995. Healing was achieved in all cases. The average amount of lengthening was 30% (range, 15-41%) of the original length. The average healing index was 82 days/cm (range, 66-113 days/cm). After the operation, range of movement of the metatarsophalangeal joint decreased in all cases (120 degrees before and 57 degrees after surgery). In two cases in which the lengthening exceeded 40% of the original length, stiffness of the joint (20 degrees and 0 degrees each) and joint deformity occurred. These two cases also had angulation of the metatarsal. Corrective osteotomy and release surgery was performed in one case. Angulation of the metatarsal was corrected, but the range of movement of the joint did not much recover after surgery. Another case was left untreated because the patient had no complaints. In metatarsal lengthening by callus distraction, the amount of lengthening should not exceed 40% of the original length.


Journal of Bone and Joint Surgery, American Volume | 1990

Osteosynthesis for old, established non-union of the lateral condyle of the humerus.

Kazuhiro Masada; Hideo Kawai; Hidehiko Kawabata; Takashi Masatomi; Yuichi Tsuyuguchi; K Yamamoto

In thirty elbows that had an established non-union of a fracture of the lateral humeral condyle that had occurred more than five years before, treatment consisted of one of three operations: anterior transposition of the ulnar nerve (nine patients), corrective osteotomy of the humerus and anterior transposition of the ulnar nerve (four patients), or osteosynthesis of the non-union combined with neurolysis and anterior transposition of the ulnar nerve, with or without corrective osteotomy of the humerus (seventeen patients). Of the thirty patients, fifteen had been apprehensive when using the elbow, due to lateral instability, or had had pain in the elbow. In thirteen of these fifteen patients, the non-union was treated by osteosynthesis. Afterward, the pain and apprehension disappeared, but the range of motion of the elbow decreased in all but three patients. Three patients had clicking between the humerus and radius, and the bone failed to unite in three others. Osteosynthesis is indicated for the treatment of non-union of the lateral humeral condyle only if the patient has serious pain in the elbow or apprehension when using the elbow, due to lateral instability.


Journal of Bone and Joint Surgery, American Volume | 2005

Modified Sauvé-Kapandji Procedure for Disorders of the Distal Radioulnar Joint in Patients with Rheumatoid Arthritis

Satoru Fujita; Kazuhiro Masada; Eiji Takeuchi; Masataka Yasuda; Yoshio Komatsubara; Hideo Hashimoto

BACKGROUND The Sauvé-Kapandji procedure has become popular for the treatment of disorders of the distal radioulnar joint in patients with rheumatoid arthritis, but this procedure is impossible to perform in patients with poor bone quality in the distal part of the ulna. We have modified the procedure for patients with poor bone quality in the distal part of the ulna. The modified procedure involves resecting the distal part of the ulna, making a drill-hole in the ulnar cortex of the distal part of the radius, rotating the resected portion of the ulna 90 degrees , inserting it into the distal part of the radius, and fixing it at that site with use of an AO cancellous-bone screw. In the present report, we describe the new operative technique and report the results after a minimum duration of follow-up of three years. METHODS This operation was performed in fifty-six patients (sixty-six wrists) with rheumatoid arthritis. The mean age at the time of the operation was 59.3 years. The mean duration of follow-up was forty-eight months. Patients were evaluated in terms of wrist pain, grip strength, and range of motion. Radiographic evaluation included calculation of the carpal translation index to assess the extent of ulnar translation of the carpus. RESULTS Osseous union was achieved in all cases. Wrist pain resolved or decreased in all patients. The mean total range of forearm rotation increased from 144 degrees preoperatively to 167 degrees at the time of the most recent follow-up (p < 0.01). The mean carpal translation index did not change after the operation. CONCLUSIONS The modified Sauvé-Kapandji procedure results in rigid fixation of the grafted bone. The technique provides sufficient osseous support of the carpus even in patients with rheumatoid arthritis and poor bone quality in the distal part of the ulna.


Journal of Bone and Joint Surgery, American Volume | 1997

Osteosynthesis for the Treatment of Non-Union of the Lateral Humeral Condyle in Children*

Kozo Shimada; Kazuhiro Masada; Koichi Tada; Tomio Yamamoto

We reviewed the results of osteosynthesis for the treatment of an established non-union of the lateral humeral condyle in sixteen children whose average age was nine years (range, four to thirteen years) at the time of the operation. The average interval between the injury and the operation was five years (range, five months to ten years). The presenting symptoms were pain in the elbow in seven patients, apprehension in nine, a cubitus valgus deformity in six, limitation of motion in three, and dysfunction of the ulnar nerve in four. The average duration of follow-up was eleven years (range, four to thirty-two years). Osseous union was achieved after the initial operation in thirteen patients. Of the three patients who had a persistent non-union, two had a second operation and the third, who was asymptomatic, refused additional operative intervention. The result was rated excellent in eight patients, good in seven, and poor in one, with use of a modification of the functional rating index of Broberg and Morrey. The patient who had a poor result had evidence of avascular necrosis of the fragment.


Journal of Bone and Joint Surgery, American Volume | 2007

Long-Term Results of Surgery for Forearm Deformities in Patients with Multiple Cartilaginous Exostoses

Shosuke Akita; Tsuyoshi Murase; Kazuo Yonenobu; Kozo Shimada; Kazuhiro Masada; Hideki Yoshikawa

BACKGROUND Surgical treatment of forearm deformities in patients with multiple cartilaginous exostoses remains controversial. The purpose of the present study was to determine the reasonable indications for operative treatment and to evaluate long-term results of forearm surgery in these patients. METHODS We retrospectively reviewed twenty-three patients (thirty-one forearms) after a mean duration of follow-up of nearly thirteen years. The mean age at the time of the initial procedure was eleven years. The patients underwent a variety of surgical procedures, including excision of exostoses; corrective procedures (lengthening of the radius or ulna and/or corrective osteotomy of the radius and/or ulna) and open reduction or excision of a dislocated radial head. Clinical evaluation involved the assessment of pain, activities of daily living, the cosmetic outcome, and the ranges of motion of the wrist, forearm, and elbow. The radiographic parameters that were assessed were ulnar variance, the radial articular angle, and carpal slip. RESULTS Four patients had mild pain, and five patients had mild restriction of daily activities at the time of follow-up. Eight patients stated that the appearance of the forearm was unsatisfactory. Radiographic parameters (ulnar variance, radial articular angle, carpal slip) were initially improved; however, at the time of the final follow-up visit, the deformities had again progressed and showed no significant improvement. The only procedure that was associated with complications was ulnar lengthening. Complications included nonunion (three forearms), fracture of callus at the site of lengthening (two forearms), and temporary radial nerve paresis following an ulnar distraction osteotomy (one forearm). Excision of exostoses significantly improved the range of pronation (p = 0.036). CONCLUSIONS In our patients with multiple cartilaginous exostoses, corrective osteotomy and/or lengthening of forearm bones was not beneficial. The most beneficial procedure was excision of exostoses. Reasonable indications for forearm surgery in these patients are (1) to improve forearm rotation and (2) to improve the appearance.


Journal of Hand Surgery (European Volume) | 1985

Congenital clasped thumb: A review of forty-three cases

Yuichi Tsuyuguchi; Kazuhiro Masada; Hidehiko Kawabata; Hideo Kawai; Keiro Ono

Over a 10-year period, 43 patients (75 hands) with congenital clasped thumb were seen in our institution. Three groups were identified: group I, 14 patients (24 hands) without contracture; group II, 14 patients (21 hands) with contractures of the palmar side; and group III, 15 patients (30 hands) with arthrogryposis multiplex congenita. Forty-two hands were treated with splinting alone and 16 hands with surgery. The remaining 17 hands were followed conservatively without splinting or surgery. The mean follow-up was 32 months. The results were evaluated by active abduction of the carpometacarpal joint and extension of metacarpophalangeal joint. All patients in group I showed good response to splinting, and the cause of the deformity appeared to be the predominance of the flexor muscles. In groups II and III, 10 patients (16 hands) who had severe deformity or no response to splinting were treated by release of the palmar soft tissues, skin grafts, and reconstruction of the extensors. Satisfactory results were obtained in 12 of 16 hands.

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