Patellar Tendon

In mature tendon, collagen fibril bundles (fibers) have diameters between 1 and 300 mm and fibrils have diameters from 20 to over 280 nm (Figure 3.28). The presence of a crimp pattern in the collagen fibers has been established for rat tail tendon as well as for patellar tendon and anterior cruciate ligament the specific geometry of the pattern, however, differs from tissue to tissue. It is not clear that the crimp morphology of tendon is actually present in tendons that are under normal resting muscular forces. 

Circumferential displacement (°) from mid-patellar tendon reference... 

Remove the skin from the ankle to the base of the hips in order to visualize the patellar tendon (Fig. 4A). 

Figure 4 Procedure for cell recovery from the tibiofemoral joint. Remove the skin under the knee (A). Cut the patellar tendon carefully with a delicate scissor (B). Open the articular cavity using tweezers (C). Dashed line can be removed for enzymatic assays (D). Wash the joint cavity with diluent (5 pL, 2x) to recover accumulated cells.

FIGURE 6.6 Force versus length curves for human medial patellar tendon, gracilis tendon, fascia lata tendon, and the anterior cruciate ligament. 

For isokinetic exercise, in which the knee is made to move at a constant angular velocity, quadriceps force decreases as knee-extension speed increases. As the knee extends more quickly, quadriceps force decreases because the muscle shortens more quickly, and, from the force-velocity property, an increase in shortening velocity leads to less muscle force (see Fig. 6.4). As a result, ACL force also decreases as knee-extension speed increases (Figure 6.26), because of the drop in shear force applied to the leg by the quadriceps (via the patellar tendon) (Serpas et al., in press). 

Use autologous structures to replace the damaged ligament, such as a section of the patellar tendon for the ACL. 

Alexander, H., Parsons, J. R., and Strauchler, I. D. (1981), Canine patellar tendon replacement with a polyactic acid polymer-filamentous carbon tissue scaffold, Orthop. Rev. 10 41-51. 

Pinar, H., and Oillquist, J. (1989), Dacron augmentation of a free patellar tendon graft A biomechanical study. Arthroscopy 5 328-330. 

FIGURE 33.9 Transtibial piosiheses historic design (left) and patellar tendon bearing (right). (Adaptedfrom Rrf. 10, Fig. 4.4.)... 

The PTB socket design, initially developed at the University of California at Berkeley in the late 1950s, accommodates the nonuniform load-bearing tolerances of the residual limb. The basic concept of the PTB socket is to distribute the load over areas of the residual limb in proportion to their ability to tolerate load. Therefore, the majority of the load is to be borne on the patellar tendon (hence the name), medial and lateral flares of the tibia, and the popliteal area. The PTB socket precompresses the residual limb tissues in these load areas so that forces are transmitted comfortably and movement of the socket relative to the skeleton is minimized.The socket is thus a replica of the residual... 

Blevins F.T., Hecker A.T., Bigler G.T., et ai (1994) The effects of donor age and strain rate on the biomechanical properties of bone-patellar tendon-bone allografts. American Journal of Sports Medicine, 22(3), 328-33. 

Patellar tendons from donors ranging in age from 17 to 54 years were tested at either 10% or 100% elongation per second, to examine effects of donor and strain rate on tensile properties. A pressure micrometer was used to measure cross-sectional area and the initial length of the tendon (from patellar to tibial insertion site) was used for strain measurements. Specimens were kept moist with a saline spray during tensile testing. Medial, lateral, and sometimes central portions were taken from 25 donors regional differences across the tendon were not considered. 

Bechtold, J.E., Eastlund, D.T., Butts, M.K., et al (1994) The effects of freezedrying and ethylene oxide sterilization on the mechanical properties of human patellar tendon. American Journal of Sports Medicine, 22(4), 562-6. 

Butler, D.L., Kay, M.D. and Stouffer, D.C. (1986) Comparison of material properties in fascicle-bone units from human patellar tendon and knee ligaments. Journal of Biomechanics, 19(6), 425-32. 

Haut, R.C. and Powlison, A.C. (1990) The effects of test environment and cyclic stretching on the failure properties of human patellar tendons. Journal of Orthopaedic Research, 8(4), 532-40. 

Sheh, M., Butler, D.L and Stouffer, D.C. (1986) Mechanical and structural properties of the human cruciate ligaments and patellar tendon. Transactions of the Orthopaedic Research Society, 11, 236. 

The popularity of bone-patellar tendon-bone graft is related to the initial quality of fixation, high initial strength and stiffness, potential for bone-to-bone healing, better stability over time, improved rate of return to sport, and overall increased activity level. Some reports draw attention to more pitfalls and serious complications using the patellar tendon procedure. The... 

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