Abstract: BACKGROUND: As a kind of medial open wedge osteotomy, distal tibial tuberosity-high tibial osteotomy has been widely used in clinical practice, but there are still few reports about the effect of this method on patellofemoral joint degeneration and patellar height.  
OBJECTIVE: To investigate the effect of distal tibial tuberosity-high tibial osteotomy on the degeneration of patellofemoral joint and patellar height.
METHODS: Totally 63 medial compartment knee osteoarthritis patients combined with mild-to-moderate patellofemoral joint degeneration, who were treated in the Third Affiliated Hospital of Beijing University of Chinese Medicine from January 2019 to January 2020, were retrospectively analyzed. There were 20 males and 43 females. They received arthroscopy cleaning technique and distal tibial tuberosity-high tibial osteotomy. All patients finished surgery and were followed up. Removal of the implant and re-arthroscopy were recommended after good healing at the fracture site. Knee 45° axial radiographs were used with Kellgren-Lawrence grading, Iwano grading and International Cartilage Repair Society grading to evaluate the degeneration of patellofemoral joint during the two operations. Caton-Deschamps index, Blackburne-Peel index and Inall-Salvati index were used to evaluate the changes of patellar height during the two surgeries. The Visual Analogue Scale and the Western Ontario and McMaster Universities Osteoarthritis Index were utilized to assess knee pain and function at the time of both surgeries. The weight bearing line ratio was used to evaluate the lower limb force line of patients during the two surgeries.  
RESULTS AND CONCLUSION: (1) All the 63 patients were followed up for 20-36 months. (2) On the knee 45° axial radiographs, Kellgren-Lawrence grading, Iwano grading and International Cartilage Repair Society grading at the second operation showed progressive changes, but there was no significant difference compared with that at the first operation (P > 0.05). (3) There was no significant difference in the patellar height measured by the three methods during the second operation compared with the first operation (P > 0.05). (4) The knee Visual Analogue Scale of pain score, Western Ontario and McMaster Universities Osteoarthritis Index score and weight bearing line ratio of the second operation were significantly better than those of the first operation (P < 0.05). (5) It is indicated that in patients with the medial compartment knee osteoarthritis combined with mild-to-moderate patellofemoral joint degeneration, but without symptoms of patellofemoral joint, treatment effect of distal tibial tuberosity-high tibial osteotomy is remarkable. The surgery could obviously relieve knee pain, improve the function of knee joint, and had no obvious effect on patellar height and patellofemoral joint degeneration in the short term.

Key words: distal tibial tuberosity-high tibial osteotomy, medial compartment, knee osteoarthritis, patellofemoral joint, degeneration