In this review, we evaluate the modern indications, subjective outcome scores, and survivorship results of unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) in the treatment of isolated medial compartment degeneration of the knee. In addition, in a thorough review of the literature, we evaluate global trends in the use of both methods. In our evaluation of articles, we note that inclusion criteria are relatively broader for UKA than for HTO, where age and body mass index should be considered before HTO surgery in order to optimize clinical outcome and survivorship results. Exact thresholds for UKA inclusion have been studied, but there is no clear definition. Both methods have good to excellent subjective outcome scores. Expected 10-year survivorship results are in favor of UKA (90%) over HTO (75%). However, controlled data directly comparing both methods are lacking. The broad range of UKA inclusion criteria and good to excellent subjective and survivorship results have led to an increase in UKA use among Western practices, whereas use of HTO in patients with isolated single-compartment osteoarthritis has been decreasing.