Rotational alignment of the knee is different in osteological specimens with and without a large cam deformity of the proximal femur.
OBJECTIVE
We studied a large osteological collection for differences in knee rotation based upon the presence or absence of a large cam deformity of the proximal femur.


METHODS
We obtained 357 matched tibiae and femora from the Hamann-Todd Osteological Collection and measured: femoral head-neck alpha angle, anteroposterior axis (or Whiteside's line) at the distal femur relative to the posterior condylar axis, and position of the tibial tubercle with respect to the posterior condylar axis of the proximal tibia. We then divided these specimens into two groups based upon alpha angle <45° (Group 1, n = 73) or alpha angle >60° (Group 2, n = 122) and performed an independent samples t-test to evaluate for differences in measured parameters between groups using this subset of specimens.


RESULTS
The mean alpha angles in Group 1 and 2 were 40.9° ± 3.3° and 67.0° ± 5.6°, respectively. Whiteside's line was externally rotated with respect to the posterior femoral condylar axis by a mean of 1.8° ± 6.8° in Group 1, vs. 3.0° ± 3.7° in Group 2 (p = 0.03). The tibial tubercle was externally rotated by a mean of 19.4° ± 6.8° in Group 1, versus 16.6° ± 5.1° in Group 2 (p = 0.003).


CONCLUSIONS
Specimens with femoral head-neck alpha angle >60° demonstrated greater external rotation of the distal femur and a more internally-rotated tibial tubercle compared to specimens with an alpha angle <45°. Differences in anatomic characteristics of the knee may play a role in the development of patellofemoral pain in patients with a large cam deformity.
Department of Orthopaedic Surgery, University Hospitals Cleveland Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio - USA.
Jeremy J
JJ
Gebhart
Department of Orthopaedic Surgery, University Hospitals Cleveland Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio - USA.
Jonathan J
JJ
Streit
Department of Orthopaedic Surgery, Brown University, Providence, Rhode Island - USA.
Avi
A
Goodman
Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan - USA.
Jordan
J
Etscheidt
Department of Orthopaedic Surgery, University Hospitals Cleveland Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio - USA.
Douglas S
DS
Weinberg
Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan - USA.
Asheesh
A
Bedi
Department of Orthopaedic Surgery, Rush University, Chicago, Illinois - USA.
Shane J
SJ
Nho
Department of Orthopaedic Surgery, University Hospitals Cleveland Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio - USA.
Michael J
MJ
Salata
D017760:Bone Malalignment / Q000175:diagnosis*; D002102:Cadaver; D005270:Femur Head / Q000002:abnormalities*; D005272:Femur Neck / Q000002:abnormalities*; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D015588:Observer Variation; D059166:Osteology / Q000379:methods; D057071:Patellofemoral Joint / Q000503:physiopathology; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D012494:Sampling Studies