Summary

MOWHTO has a positive effect on the medial cartilage and meniscus in middle term. When a meniscectomy was performed, MME tended to progress.

Abstract

Purpose

Medial Opening-Wedge High Tibial Osteotomy (MOWHTO) affects the medial compartment positively on arthroscopy and MRI in short term. Middle- to long-term effects are not clear. The purpose was to evaluate the effects of MOWHTO on the meniscus and cartilage of the medial compartment on MRI for up to 9 years.

Methods

Subjects were 24 knees that underwent MOWHTO for osteoarthritis and osteonecrosis, including 5 knees combined microfracture, 7 knees combined with medial meniscus partial resection for flap degenerative injury, and 5 all MMPRT were not treated. We evaluated X-rays and serial MRIs. The MRI was performed pre-operation, early-term (1-2 years), and mid-term (5-9 years) postoperatively. We evaluated the MOCART score, the T2 relaxation times of each cartilage, and the extrusion of the medial meniscus (MME).

Results

The X-ray course was as follows, preoperative %MA 32% mid-term 62%, MPTA 85 degrees before surgery, and 92 degrees in the middle term. The MOCART score was kept from the early to the middle term. The score was the lowest in the combination with MF. ‘Volume score’ was lower in MF and meniscus resection. ‘Subchondral bone score’ was the lowest in the MF group. T2 relaxation times in the medial femoral condyle and tibial plateau decreased statistically (P < .05). In MOWHTO combined with MF, both the femur and tibia tended to deteriorate toward the middle term. There were no statistical differences in MME, while two cases were improved. The amount of MME was 5.9±1.7mm in pre-operation, 6.7±3.4mm in the early term, and 7.3±2.5 mm in the middle term, when a partial meniscectomy was performed. Each MME amount was 3.6±2.1 in pre-operation, 4.9±1.8 in the early term, and 4.3±3.3mm in the middle term, when the meniscus was unresected.

Conclusion

Mid-term MRI images were evaluated. MOWHTO has a positive effect on the medial cartilage and meniscus, but it has not been sufficiently repaired on the MRI. When a meniscectomy was performed, MME tended to progress. Reconstruction of cartilage and meniscus can be expected to improve the long-term evaluation of osteotomy.