Recurrent patellar instability is a disabling condition that can lead to articular cartilage injuries, osteochondral fractures, pain, decreased activity, and patellofemoral osteoarthritis (OA). Aim of the work: To evaluate Clinical and Radiological evaluation of Trochleoplasty in cases with trochlear dysplasia. Patients and Methods: In between2018 and2020 a prospective comparative study of cases suffered from recurrent patellar dislocation with trochlear dysplasia at knee surgery, sports medicine and arthroscopy unit- Mansoura University. The patients were divided in to two group, group 1treated by Trochleoplasty combined with MPFLR versus cases treated by MPFLR (group 2). All patients were trochlear dysplasia type (B, D). Results: In our study13 cases had treated by MPFLR only one case needed tibial tubercle transfer, they had a minimum follow-up period of2years and were able to show an improvement in Kujala scores from (59.0±9.29) to (75.53±9.61) p≤0.001. The visual analogue scale decreased from (6.92) to (2.66±0.61) p≤0. 001.NO dislocation rates were reported. In our study j sign was observed in 7 cases preoperative and one case had persistent g sign postoperative due to weak vmo muscle. In which the sulcus angle decreased from 150.5±6.91preoperative to 143.4±8.19 (p=0.003) at the final follow up, the congruence angle decreased from46 preoperative to 9(p=0.013), patellar tilt angle decreased from 14.5 to 7(p≤ 0.001), tibial tuberosity trochlear groove distance decreased from 2.25to 1.9(p≤0.001). Conclusion: The clinical significance of the present study indicates that the combinatory treatment concept of trochleoplasty and MPFLR may serve as a valuable option not only as salvage therapy but also as primary procedure regarding treatment for chronic PFI.