Maturation-dependent change and regional variations in acoustic stiffness of rabbit articular cartilage: an examination of the superficial collagen-rich zone of cartilage

OBJECTIVE

The purpose of the study was to investigate maturation-dependent changes of acoustic (ultrasound) stiffness and other ultrasound features of articular cartilage in healthy rabbit knees.

METHODS

Five groups of rabbits of various ages (3 weeks, 8 weeks, 6 months, 1 year, 2.5 years) consisting of five rabbits per group were examined. Signal intensity (index of stiffness), signal duration (index of surface irregularity) and interval between signals (index of thickness) of the ultrasound reflection from articular cartilage were examined at four sites: posterior lateral femoral condyle, posterior medial femoral condyle, lateral tibial plateau, and medial tibial plateau. The sites were observed macroscopically and microscopically with a light microscope and a polarized light microscope.

RESULTS

At the lateral and medial condyles and the lateral tibial plateau, signal intensity was least in 3-week-old specimens. The intensity increased until 6 months or 1 year of age. At these sites, the signal durations and intervals between signals were least at the ages of 6 months or 1 year. At the medial tibial plateau, the intensity was the least at 2.5 years of age and the interval between signals was least at 3 weeks of age; there was no effect of age on signal duration. Cartilage surfaces of all specimens were smooth and no degenerative changes were macroscopically or microscopically evident. The surface brightness of cartilage under the polarized light microscope was consistent with signal intensity values.

CONCLUSIONS

The response of articular cartilage to ultrasound was maturation-dependent. Acoustic properties differed from mechanical stiffness properties, which were determined using indentation. Ultrasound may detect properties of the surface collagen of the articular cartilage.

[Two successful surgical cases of total left anomalous pulmonary venous connection with intact atrial septum--a report on their operative procedures and approaches]

Partial anomalous pulmonary venous connection (PAPVC) is often associated with other congenital heart diseases. Atrial septal defect, particularly, appears in about ninety percent of patients with PAPVC. Successful repairs were made in two patients of total left PAPVC with intact atrial septum. In one patient, left thoracotomy was made, and the vertical vein was anastomosed to the left atrial appendage. Cardiopulmonary bypass was not used in this case. In the other patient, median sternotomy was made, and the vertical vein was anastomosed to the posterior wall of the left atrium under cardiopulmonary bypass. Although postoperative prognosis are excellent sofar in both cases. We consider that the latter operative procedures are preferable for PAPVC not associated with atrial septal defect. In the present paper, the detailed operative procedures and approaches for these two cases are reported, and the concerning literatures are discussed.