Effect of open wedge high tibial osteotomy on the lateral compartment in sheep. Part I: Analysis of the lateral meniscus.
OBJECTIVE
To evaluate whether medial open wedge high tibial osteotomy (HTO) results in structural and biochemical changes in the lateral meniscus in adult sheep.


METHODS
Three experimental groups with biplanar osteotomies of the right proximal tibiae were tested: (a) closing wedge HTO resulting in 4.5° of tibial varus, (b) open wedge HTO resulting in 4.5° of tibial valgus (standard correction) and (c) open wedge HTO resulting in 9.5° of valgus (overcorrection), each of which was compared to the contralateral knees with normal limb axes. After 6 months, the lateral menisci were macroscopically and microscopically evaluated. The proteoglycan and DNA contents of the red-red and white-white zones of the anterior, middle and posterior third were determined.


RESULTS
Semiquantitative macroscopic and microscopic grading revealed no structural differences between groups. The red-red zone of the middle third of the lateral menisci of animals that underwent overcorrection exhibited a significant 0.7-fold decrease in mean DNA contents compared with the control knee without HTO (P = 0.012). Comparative estimation of the DNA and proteoglycan contents and proteoglycan/DNA ratios of all other parts and zones of the lateral menisci did not reveal significant differences between groups.


CONCLUSIONS
Open wedge HTO does not lead to significant macroscopic and microscopic structural changes in the lateral meniscus after 6 months in vivo. Overcorrection significantly decreases the proliferative activity of the cells in the red-red zone of the middle third in the sheep model.
Center of Experimental Orthopaedics, Saarland University, Kirrbergerstr. 1, Bldg 37, 66421, Homburg, Saar, Germany. henning.madry@uks.eu
Henning
H
Madry
Raphaela
R
Ziegler
Patrick
P
Orth
Lars
L
Goebel
Mei Fang
MF
Ong
Dieter
D
Kohn
Magali
M
Cucchiarini
Dietrich
D
Pape
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D017760:Bone Malalignment / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D004247:DNA / Q000378:metabolism; D008592:Menisci, Tibial / Q000378:metabolism / Q000473:pathology*; D010027:Osteotomy / Q000009:adverse effects* / Q000379:methods; D011509:Proteoglycans / Q000378:metabolism; D012756:Sheep; D013977:Tibia / Q000601:surgery*
D015415:Biomarkers; D011509:Proteoglycans; D004247:DNA