2015 ISAKOS Biennial Congress ePoster #1726

Limitation of the High Tibial Osteotomy (HTO) and Indication of the Double Osteotomy

Satomi Abe, MD, Asahikawa, Hokkaido JAPAN
Hitoshi Nochi, MD, PhD, Asahikawa, Hokkaido JAPAN
Hiroshi Ito, Sapporo JAPAN

Asahikawa Medical University, Asahikawa, JAPAN

FDA Status Cleared

Summary: We found some cases which should have had a double osteotomy in order to keep natural physiological joint line.

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Abstract:

Purpose

When the varus deformity is located at the femur or both femur and tibia, a single osteotomy at the tibia will result in an unphysiological joint line. To avoid joint-line divergence, a double osteotomy could be a better procedure.
The purpose of this study is to explore retrospectively a location of the deformity and a joint line inclination after HTO procedure.

Methods

We evaluated the radiographs of 36 knees, which we performed HTO from 1977 to 1998 and follow-up over the next 15 years on average. We evaluated aLDFA, mLDFA, MPTA, JLCA and joint line inclination angle (JIA), which is the lateral angle of the mechanical line for the mid joint line, at pre-op., post-op.1 year, and the final follow up. We assigned U-group (FTA: more than 170°) and A-group (FTA: 164-170°) at post-op. 1 year. We assigned NO-group (MPTA: 85-94°) and OV-group (MPTA: more than 95°) at the final follow up.

Results

There were 12 knees, in which aLDFA or mLDFA was larger than normal. There were 13 knees, in which MPTA was lower than normal. We found 5 knees with abnormalities in the both femur and tibia. At pre-op., aLDFA and mLDFA in U-group (88.5°and 91.8°) was larger than in A-group (81.5°and 88.0°), no statistical difference. At pre-op., MPTA in U-group (81.5°) was smaller than MPTA in A-group (88.0°), no statistical difference. At pre-op., post-1 year and the last follow up, MPTA in A-group was larger than MPTA in U-group, no statistical differences, however MPTA in A-group exceeded the normal value of 5°. We found a positive correlation with mLDFA at pre-op. and MPTA at the final follow up. There was statistical difference (P<0.01) between JIA in NO-group(92.6°) and in OV-group (96.2°), this means that the joint line inclined laterally in OV-group. There was no statistical difference between JLCA in NO-group (2.6°) and in OV-group (2.4°), but we found a medial side laxity in OV-group.

Discussion

When a varus deformity resulted in a femoral deformity, MPTA at the post-op. seemed to be larger. This study showed that, subsequently, MPTA after HTO exceeded normal value, and the joint line inclined laterally. In this study we found some cases which should have had a double osteotomy in order to keep natural physiological joint line, although we should consider the degree of the degeneration and age.