The geometry of the trochlear groove.
BACKGROUND
In the natural and prosthetic knees the position, shape, and orientation of the trochlea groove are three of the key determinants of function and dysfunction, yet the rules governing these three features remain elusive.


OBJECTIVE
The aim was to define the three-dimensional geometry of the femoral trochlea and its relation to the tibiofemoral joint in terms of angles and distances.


METHODS
Forty CT scans of femurs of healthy patients were analyzed using custom-designed imaging software. After aligning the femur using various axes, the locations and orientations of the groove and the trochlear axis were examined in relation to the conventional axes of the femur.


RESULTS
The trochlear groove was circular and positioned laterally in relation to the mechanical, anatomic, and transcondylar axes of the femur; it was not aligned with any of these axes. We have defined the trochlear axis as a line joining the centers of two spheres fitted to the trochlear surfaces lateral and medial to the trochlear groove. When viewed after aligning the femur to this new axis, the trochlear groove appeared more linear than when other methods of orientation were used.


CONCLUSIONS
Our study shows the importance of reliable femoral orientation when reporting the shape of the trochlear groove.
Iranpour
Farhad
F
Division of Surgery, Oncology, Reproductive Biology and Anaesthetics, Department of Musculoskeletal Surgery, Imperial College London, 7th Floor, Charing Cross Hospital, London, UK. f.iranpour@imperial.ac.uk
Merican
Azhar M
AM
Dandachli
Wael
W
Amis
Andrew A
AA
Cobb
Justin P
JP
D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D008875:Middle Aged; D010329:Patella / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D011859:Radiography; D013977:Tibia / Q000033:anatomy & histology* / Q000000981:diagnostic imaging