Patellar luxation is common in small breed dogs and is often treated surgically. This study compares the long-term outcomes of two surgical techniques, trochlear wedge recession (TWR) and trochlear block recession (TBR), for medial patellar luxation (MPL) with regard to osteoarthritis (OA) progression. High inter-observer agreement was hypothesized for the use of a modified OA scoring system and fewer OA changes in the TBR group. This study included 25 dogs (<15 kg) with grade-2 or -3 MPLs treated at the University of Veterinary Medicine Vienna (2016-2021). A total of 32 stifle joints (TWR Group n = 11, TBR Group n = 21) were evaluated pre-operatively and at least one year post-operatively using a modified OA scoring system. A statistical analysis was conducted to compare OA progression between the techniques. The inter-observer agreement was high. The OA scores increased in both groups post-operatively, with TBR demonstrating a greater progression at specific points. Overall, no significant differences were found between the techniques. These findings suggest that OA progression does not significantly differ between TWR and TBR. The modified OA scoring system has shown to be reliable for assessing OA progression after treatment. Further prospective studies with larger study populations incorporating clinical assessments are needed for a better understanding of the surgical impacts on OA development.