Background An iatrogenic lateral hinge fracture is a common intraoperative problem that may occur during medial open wedge high tibial osteotomy (MOWHTO). This study aims to assess the significance of using additional crossing lateral K-wires and their advantage in protecting the lateral hinge during MOWHTO procedures. Methods The data of patients fulfilling the inclusion criteria who underwent MOWHTO between May 2021 and August 2022 were retrospectively evaluated. One group had additional lateral hinge crossing K-wires (+ MOWHTO group), while the other did not (-MOWHTO group). Both groups were assessed for rate of intraoperative lateral hinge fractures, knee injury and osteoarthritis outcome score − 12 (KOOS-12), medial proximal tibial angle (MPTA), time of union, and time to return to work. The outcomes were compared using the independent T-test for continuous variables and the Fisher Exact test for nominal variables. A p-value of < 0.05 was considered statistically significant for both tests. Results The study included forty-eight patients; twenty-four in each treatment group. The mean follow-up durations were 30.5 ± 3.6 months for + MOWHTO and 31.6 ± 3.2 months for –MOWHTO (p = 0.26). There was no statistically significant difference regarding mean age, sex, KOOS-12, MPTA, and time of surgery between both groups. The + MOWHTO group had a faster time of union (p = 0.001), an earlier return to work (p = 0.002), and a lower rate of intraoperative lateral hinge fractures (p = 0.04). Conclusion This study demonstrated that using additional crossing lateral K-wires during MOWHTO had a beneficial effect on reducing the rate of iatrogenic lateral hinge fractures, with a faster time of union, and an early return to work. The KOOS-12, MPTA, and mean operative time did not reveal significant differences between treatment groups.