Association between mechanical axis of the leg and osteochondritis dissecans of the knee: radiographic study on 103 knees.
BACKGROUND
The cause of osteochondritis dissecans (OCD) is unknown, but mechanical factors seem to play a role.


OBJECTIVE
To identify a relationship between localization of OCD and mechanical axis of the leg.


METHODS
Case series; Level of evidence, 4.


METHODS
Using bilateral full-leg standing radiographs, we analyzed the position of the mechanical axis of the leg in a group of 93 adolescent and adult patients (103 knees) with OCD of the medial or lateral femoral condyle.


RESULTS
The location of OCD and the position of the mechanical axis in the same knee compartment was significantly correlated for both knees with medial (P < .001) as well as lateral (P < .012) compartment OCD. In the medial OCD group, the mean mechanical axis was located in the medial knee compartment (28% medial +/- 2.8%; range, 100% medial to 14% lateral) with a statistically insignificant medial shift with respect to the unaffected side. In lateral OCD, the mean mechanical axis was located laterally (13% lateral +/- 3.9%; range, 13% medial to 60% lateral) with a significant shift from the medial into the lateral knee compartment when comparing unaffected with affected knees. No significant difference was observed between adolescents with open growth plates compared with adults with closed growth plates (P > .05).


CONCLUSIONS
We found an association between medial condyle OCD and varus axis and between lateral condyle OCD and valgus axis. This evokes higher loading of the affected than of the unaffected knee compartment, and therefore, axial alignment may be a cofactor in OCD of the femoral condyles.
Jacobi
Matthias
M
Department of Orthopaedic Surgery, Hôpital Cantonal Fribourg, 1708 Fribourg, Switzerland. jacobim@h-fr.ch
Wahl
Peter
P
Bouaicha
Samy
S
Jakob
Roland P
RP
Gautier
Emanuel
E
D000293:Adolescent; D005260:Female; D006801:Humans; D007717:Knee / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000503:physiopathology; D007866:Leg / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D010008:Osteochondritis Dissecans / Q000000981:diagnostic imaging / Q000209:etiology*; D011859:Radiography; D012189:Retrospective Studies; D055815:Young Adult