Waseda University · Medicine
Professor Tsukasa Kumai's research lab specializes in orthopedic surgery and sports medicine, with a primary focus on ankle joint disorders, particularly osteochondral lesions of the talus and ligament injuries. The lab investigates minimally invasive surgical techniques, such as arthroscopic drilling and cortical bone grafting, to treat chronic ankle instability and degenerative joint conditions. A key research direction involves understanding the anatomical and histological basis of tendon and ligament injuries, including the role of entheses and extracellular matrix composition in injury susceptibility and healing. The lab also explores implant design and long-term outcomes in ankle arthroplasty, emphasizing prosthesis stability and biocompatibility.
Figures are computed from collected data and may differ slightly.
Arthroscopic drilling for the treatment of medial osteochondral lesions of the talus does not require osteotomy of the medial malleolus or postoperative immobilization; thus, the procedure is less invasive than other types of operative treatment for the condition and it allows early resumption of daily activities and sports. On the basis of the results in this study, we believe that the procedure is effective and useful in young patients, especially those who have not yet had closure of the epip
The anterior talofibular ligament is the most commonly injured ligament in the ankle. Despite considerable interest in the clinical outcome of treatment protocols, we do not know whether the distinctive pattern of localization of the injuries relates to regional differences in the structure and molecular composition of the ligament. To address this issue, ligaments were examined by histology and immunohistochemistry. Differences in the structure of its two attachments (i.e. entheses) were evalua
Contrary to popular belief, subcalcaneal heel spurs cannot be traction spurs as they do not develop within the plantar fascia itself. They are thus fundamentally different from heel spurs in the Achilles tendon. We suggest instead that they develop as a consequence of degenerative changes that occur in the plantar fascia enthesis.
Ankle arthroplasties using metal and polyethylene prostheses were done on 28 patients (30 ankles) with painful osteoarthritis or rheumatoid arthritis between 1975 and 1980. Significant loosening and subsidence of the metal prostheses occurred in most patients, and ceramic prostheses were introduced in 1980. Ceramic prostheses with or without cement were used to replace 60 ankles in 56 patients with painful arthritis between 1980 and 1991. Revision surgery was required for five patients (five ank
We have treated osteochondral lesions of the talus using cortical bone pegs. We examined 27 ankles (27 patients) after a mean follow-up of 7.0 years (2 to 18.8). The mean age of the patients was 27.8 years (12 to 62). An unstable osteochondral fragment or osteosclerotic changes in the bed of the talus were regarded as indications for the procedure. The clinical results were good in 24 ankles (89%) and fair in three (11%); none had a poor result. There was also radiological improvement in 24 ankl
The peroneal (fibularis) tendons are held in place within the malleolar groove by the superior peroneal retinaculum. If this is torn, the tendons can subluxate or dislocate. Understanding the anatomy of the region is important for treating these injuries when it becomes necessary to reconstruct the malleolar groove surgically. Serial transverse sections of the groove were cut from 10 dissecting room cadavers after routine histology processing. The structure of the malleolar groove differed signi
Histopathological analysis was performed on 55 feet in 48 patients with nonosseous tarsal coalitions. Histological findings were similar to those observed at the tendinous attachment site of Osgood-Schlatter disease, accessory navicular, and bipartite patellae. No nerve elements were observed in the fibrocartilaginous tissue at the coalition. Nerve elements were present only in periosteum and articular capsule surrounding the coalition. Pain in the tarsal coalition is not mediated by nerve eleme
We have treated osteochondral lesions of the talus using cortical bone pegs. We examined 27 ankles (27 patients) after a mean follow-up of 7.0 years (2 to 18.8). The mean age of the patients was 27.8 years (12 to 62). An unstable osteochondral fragment or osteosclerotic changes in the bed of the talus were regarded as indications for the procedure. The clinical results were good in 24 ankles (89%) and fair in three (11%); none had a poor result. There was also radiological improvement in 24 ankl
Clinical analysis was performed on 60 feet in 40 patients with isolated first naviculocuneiform coalitions. The most common symptom was a mild pain at the medioplantar site of the first naviculocuneiform joint. Fifteen feet (25%) were asymptomatic. Some cases had been treated erroneously as osteoarthritis or bony cyst before diagnosis. We divided coalitions morphologically into three patterns based on computed tomography findings: irregular, cystic, and combined pattern. Based on the mean age of
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The ligamentum capitis femoris (LCF) has increased in clinical significance through the development of hip arthroscopy. The histological pathologies and molecular composition of the femoral attachment of the LCF and the degeneration caused by LCF disruption were investigated in the human hip joint. Twenty-four LCFs were retrieved at surgery for femoral neck fracture (age range: 63-87 years). In the "intact" (i.e., intact throughout its length, n = 12) group, the attachment consisted of rich fibr
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