The morphometric and biomechanical characteristics of ligaments of the knee joint, with special reference to the anterior cruciate ligament, have been investigated by means of x-radiography, light microscopy, scanning electron microscopy (SEM), mercury strain gauge analysis, and tensile testing.

From radiographs the spatial orientation of the anterior cruciate ligament was determined:​ (1) in the anterior view, it produced a 12° angle with vertical references line, (2) in the medial view, it produced a 60° angle with the horizontal reference line.

From morphometric analysis of the cruciate ligaments it was found that the anterior cruciate ligament had a length of 5.0 ± 01 cm and a weight of 2.6 ± 0.3 g while the posterior cruciate had a mean length of 5.2 ± 0.3 cm and a weight o 5.3 ± 0.5 g, both parameters being taken from fresh specimens.

The association between the anterior cruciate and the ligamentum mucosum, synovial membrane, both menisci and gemur and tibia was described. The fascicular pattern was found to change throught the length of the ligament:​ (1) an increase in inter-fascicular loose connective tissue accounted for a larger cross-sectional area near the bony attachment, (2) fascicules in the middle one-third of the ligament appeared larger and more circular, while those near the bony attachment were smaller and irregular. Nerve fibres were found in two positions:​ (1) famifying freely throughout the ligaent, (2) in a perivascular position. Blood vessels were found:​ (1) in a retro-synovial position, (2) ramifying freely in a mid-fscucular position, (3) in an inter-fascicular position. With minor differences the ligamentous insertions into bone resembled those described for tendons.

From the SEM studies the micro-architectural structure of ligamentour sub-units was observed. Cross-banding on the fibrils, collagen fibres, sub-fascicules, fascicules, endotonon, peritenn and epitenon were all visualized. Stereo-pairs were made in order to demonstrate the networks of inter-lacing fibirils which comprise the fibres.

By using a mercury strain gauge method it was shown that anterior curciate tension varies according to the position of the knee joint and to stresses which may be applied through the line of articulation. Maneuvers which tighten the ligament include extension of the joint, application of varus stress, medial rotation of the tibial up the fixed femoral condyles, and anterior drawering. Tension of the anterior cruciate reaches a miniminum between 30 and 40 degrees.

With 5 ml increments of injected aline, intra-capsular pressure wasfound to vary according to the degree of flexion at the knee joint. Maximum pressures were observed both at forced flexion and hyperextension, while a minimum was apparent in the vicinity of 45° flexion.

Freshhuman anterior cruciate ligaments tested in a tensile manner failed at a greater load and strain at a fast strain rate than at a slow strain rate. Of the three ligaments, the two cruciates and medial collateral, the posterior curciate was the strongest. Factors found to influence the strength of a ligament include:​ (!) gauge length of ligament sample, (2) strain rate, (3) clamping device, (4) cross-sectional area.