We used a previously reported experimental method to measure
patellofemoral contact areas and pressures in four pairs of human cadaveric
knees before and after a partial patellectomy. The knee joints were loaded
by application of a flexion moment, which was resisted by the extension
moment of the quadriceps mechanism. Patellofemoral contact was measured
with the use of pressure-sensitive film, at 30, 60, and 90 degrees of
flexion of the knee. Partial patellectomy decreased the patellofemoral
contact area and increased pressure. We observed alterations in the
patterns of contact, including a proximal shift in patellofemoral contact,
after partial patellectomy. An anterior reattachment of the patellar tendon
significantly minimized the effects of 20 and 40 per cent patellectomies (p
< 0.05). After a 60 per cent patellectomy, patellofemoral contact was
altered markedly, with the contact area reduced to less than 50 per cent of
the control values regardless of the position of the patellar tendon
reattachment.