Comparable Maintenance of Tibial Slope in Two High Tibial Osteotomy Techniques

OBJECTIVES: High tibial osteotomies (HTO) are commonly performed to correct coronal malalignment in young, active patients who have concomitant cartilage lesions and/or cruciate ligament insufficiency. An unintended change of native tibial slope can negatively affect both the strain on reconstructed cruciate ligaments and the contact forces on cartilage. Therefore, one of the goals when performing an HTO is to minimize any change in posterior tibial slope. This study was designed to determine if there is a time zero difference in the maintenance of native tibial slope when performing valgus producing opening wedge HTOs using two distinct surgical techniques and fixation devices. METHODS: Controlled Laboratory Study. Experienced surgeons performed valgus producing opening wedge HTOs in 24 matched paired cadaveric specimens using free hand (FH, n=12) and biplanar cutting jig (Jig, n=12) techniques. Digital fluoroscopy was used to capture anteroposterior and lateral images in all specimens, and the angle of posterior tibial slope (TS) was measured using digital software (NIH image; Bethesda, MD) in a manner blinded for technique and fixation. RESULTS: There was good to excellent intra- and inter-observer reliability with the measurement technique using a Model 3, k, intra-class correlation coefficient (ICC). Both observers’ measurements passed tests for homogeneity (p=0.07, and p=0.12). There was no significant change in the maintenance of tibial slope between JIG and FH groups for observer 1 [JIG = 2.40° (SD = 1.3°) FH= 2.95° (SD=2.89°), p = 0.55] or observer 2 [JIG = 2.32° (SD = 2.5°) FH = 3.14° (SD=3.3°), p = 0.49]. CONCLUSION: When performing a valgus producing opening wedge HTO, neither the cutting jig nor the free hand technique maintained native posterior tibial slope. Both techniques increased posterior tibial slope by an average of 2-3° with no significant difference between the groups. This change in posterior tibial slope is consistent with previously reported values in the literature.