Abstract
Orthopedic surgeons are taught to remove the under surface of the patella in accordance with the thickness of polyethylene used to replace an equivalent amount of bone. Inability, however, to obtain a symmetrical removal of bone can lead to subluxation, increased tension producing pain, and affect range of motion. A convenient and fast way to recognise this asymmetry and remove an additional sliver of bone from the patella would be an advantage in creating a patella of even thickness.
Eight orthopedic surgeons were asked to evaluate 24 pre-cut patellar specimens with varying asymmetric thicknesses in a bag without visualisation. By feeling the patella between the thumb and forefinger, they were instructed to identify the thickest portion of the patella as well as to determine the difference in thickness between the thinnest and thickest sides. Two trials were conducted with each orthopedic surgeon consecutively.
Orthopedic surgeons were able to determine through proprioception the thickest one-half of the patella 91% of the time. This did correlate with experience in total knee arthroplasty. They were able to differentiate a 1 mm difference in patellar asymmetry 36% of the time, a 2 mm difference 61% of the time, and a 3 mm difference 81% of the time.
Orthopedic surgeons can identify an asymmetrically cut patella by assessing thickness of the patella between their thumb and forefinger the majority of the time. By doing this technique, inadvertent asymmetrically thick patellas at the time of total joint arthroplasty can be min-imised. This technique should be incorporated into the standard regimen of performing total knee arthroplasties.
The abstracts were prepared by Nico Verdoschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, Universitair Medisch Centrum, Orthopaedie / CSS1, Huispost 800, Postbus 9101, 6500 HB Nijmegen, Th. Craanenlaan 7, 6525 GH Nijmegen, The Netherlands.
