The effect of tibial rotation on knee medial and lateral compartment contact pressure

The progression of knee osteoarthritis (OA) is determined in part by mechanical effects on local structures. The mechanical influences of limb malalignment on cartilage loss are well known; however, the effect of rotational deformities on knee OA is not yet known. The aim of the current study was to evaluate the effect of tibial rotation on knee medial and lateral compartment contact pressure. The left knees of six fresh whole-body cadavers were used in this study. Fujifilm Prescale super-low type film was used for contact pressure measurement. The films were inserted into the joint after arthrotomy. The cadavers were stabilized with a custom-made device, and axial force of half body weight specific to each cadaver was applied to the plantar surface of the feet. The examination was repeated after osteotomy of the fibula and tibia, and the tibia was then rotated 15A degrees or 30A degrees internally (IR) or externally (ER) and securely fixed. The resulting films were scanned, and CP was determined using appropriate software. The p values for increased medial compartment contact pressure at 15A degrees and 30A degrees IR and 30A degrees ER were 0.016, 0.025, and 0.025, respectively. For decreased medial compartment contact pressure at 15A degrees ER, the p value was 0.020. The p values for increased lateral compartment contact pressure at 15A degrees and 30A degrees ER were 0.010 and 0.030, respectively. In this compartment, contact pressure changes at 15A degrees and 30A degrees IR were not significant. This experimental study demonstrated that 15A degrees IR of the tibial shaft increased contact pressure and 15A degrees ER decreased contact pressure over the knee medial compartment.