The remained patellar tendon strength after central one third removal : a biomechanical study.

ABSTRACT

The study was aimed at comparing the ultimate load bearing capabilities between normal patellar tendons (control group) and tendons after central one-third removal (removal group). Eleven fresh Thai cadavers provided study specimens. The average age of the cadavers was 24.86 +/- 7.13 years. Five tendons were used as control specimens and another six tendons underwent central one-third removal. The Instron 5583 testing machine and Cooper's technique of measurements were used to test the ultimate load. Rate of elongation of tendon was set at 500 mm/sec. The results showed that the removal group cross-sectional area was 48.67 mm2 or 49.64 per cent of the control group (98.04 mm2). The mean ultimate load of the control group was 4,365.59 N. The mean ultimate load of the removal group was 2,226.58 N or about 51 per cent. The energy level to breaking point in the control group was 72.17 J and 32.58 (45.14%) in the removal group. The average width of the central one-third portion was measured at 8.68 +/- 0.56 cm. Generally in a clinical situation, when the ultimate load is reduced to about half in the donor knee, care must be taken before allowing full weight to bear. Caution should also be emphasized in cases where a routinely 10 mm wide graft has been taken, as the donor tendon may be weakened by more than half and may rupture prematurely.