Takashi Toyoda

Tensile load and the metabolism of anterior cruciate ligament cells.

It generally is recognized that tensile load plays a major role in maintaining the homeostasis of the anterior cruciate ligament fibers, but its detailed mechanism remains a matter of controversy. The effects of cyclic tensile load on the metabolism of the anterior cruciate ligament were investigated experimentally using cultured cells from the anterior cruciate ligament of rabbits. Using culture plates with flexible rubber bases, a cyclic tensile load was applied to the cultured cells for 24 hours, and the changes in shape, alignment, and metabolism of the cells were analyzed. Under the cyclic tensile load, the shape of the cells from the anterior cruciate ligament changed to spindle and aligned perpendicularly to the direction of the tensile load. The cyclic tensile load also caused an increase in collagen synthesis by the cells from the anterior cruciate ligament, which was predominant in Type I. The cells from the synovium showed similar changes in shape and alignment under the cyclic tensile load, but no significant change was observed in cell metabolism. These observations suggest that the application of cyclic tensile load on the anterior cruciate ligament cells is an important factor in the regulation of collagen synthesis in the anterior cruciate ligament.

Heterotopic ossification after total knee arthroplasty

The incidence of heterotopic ossification (HO) after total knee arthroplasty (TKA) and its effect on the postoperative range of motion (ROM) were assessed in 63 primary TKAs. Twenty-five of 63 knees (39%) showed postoperative HO, most of which were found in the region anterior to the distal femur. The incidence of HO was significantly higher (P <.05) in the osteoarthritic knees than in the rheumatoid knees. Significant positive correlation was seen between the preoperative grade of osteophyte formation and the incidence of postoperative HO. The ROM in the knees with HO was not significantly different than that in the knees without HO at 1 year after surgery. Thus, we concluded that HO after TKA is a self-limiting condition and its pathogenesis is completely different from that of myositis ossificance.

The effects of tensile load on the metabolism of cultured chondrocytes.

The effect of cyclic tensile load on articular cartilage metabolism was investigated experimentally using 12 Japanese White rabbits. Chondrocytes obtained from the knee joints were cultured on plates with flexible silicone rubber bases. They were subjected to a cyclic (3 seconds on and 3 seconds off) tensile load for 24 hours with a maximum increase in area of 17%. Proteoglycan synthesis, collagen synthesis, and tissue inhibitors of metalloproteinases production by the chondrocytes under the load were quantified and compared with those produced by the control cells in an unloaded condition. The cultured chondrocytes under the cyclic tensile load perpendicularly aligned to the direction of the tensile load. Collagen synthesis and tissue inhibitors of metalloproteinases production increased significantly under the cyclic tensile load, although no significant change in proteoglycan synthesis was observed. These results suggested that the cyclic tensile load on the chondrocytes contribute to the regulation of articular cartilage metabolism in part.

Bone loss of the radius in rheumatoid arthritis Comparison between 34 patients and 40 controls

We measured bone mineral density (BMD) in the radius by dual energy X-ray absorptiometry in 34 patients with rheumatoid arthritis (RA) and in 40 healthy controls. The BMD in RA patients in their fifties and sixties, but not in their forties and seventies, was significantly lower than that in the control subjects. The decrease in total radial BMD correlated with grip strength, RA activity and RA stage. The decrease in distal radial BMD correlated with RA activity, but not with grip strength. The levels of serum parathyroid hormone, alkaline phosphatase, and urinary hydroxyproline/creatinine were significantly higher in the patients. From these findings, we suggest that the bone loss in RA patients is affected by severity of inflammation, disuse, postmenopausal osteoporosis and secondary hyperparathyroidism.

The end-point and the remnant of the injured cruciate ligaments of the knee

Abstract The relationship between the remnant of the injured cruciate ligaments and the end-point was investigated by analyzing quantitatively the magnitude and stiffness of anterior–posterior instability using a knee arthrometer (KT-2000). Thirty-eight normal subjects, 44 chronic ACL injuries and 20 chronic PCL injuries were involved. In the ACL injury, the magnitude of the displacement increased regardless of the remnant condition, but the stiffness reduced when no remnant or only a stump was observed. In the PCL injury, the magnitude increased but the stiffness remained normal, which corresponds to clinical findings, as a thick remnant is often left in the PCL injury.

Arthroscopic Treatment of Tibial Eminence Avulsion Fracture With Suture Tensioning Technique

Although a tibial eminence avulsion fracture is a rare knee injury, it can result in some complications such as nonunion, limited range of motion, and anterior instability of the knee if the displaced fracture is not well reduced. Arthroscopic procedures for this fracture have been commonly performed in recent years. In patients with small fragments, a pullout operation is usually performed, but arthroscopic suture reduction is technically difficult. In addition, anterior instability of the knee may remain even if the fragment is well reduced at the time of the surgical procedure. Generally, surgeons are concerned about anatomic reduction compared with appropriate tensioning during surgery. Therefore, one of the key points to avoid remaining anterior instability of the knee is to obtain and maintain appropriate tensioning. The purpose of this article is to present an easy and safe technique for acquisition of appropriate tensioning using a tensioning device for tibial eminence avulsion fractures. Although it has limitations, this technique can facilitate the reduction of tibial eminence avulsion fractures and appropriate tensioning of the anterior cruciate ligament.