Effect Of Open Wedge Tibial High Osteotomy On The Patellar Position And Patellofemoral Articular Cartilage

Objective:With the concept of"knee-saving"is gaining popularity,the opening-wedge tibial high osteotomy(OWHTO)is becoming increasingly popular among surgeons and patients as a"knee-saving"surgery.Although its clinical efficacy has been widely recognized,and both short-term and long-term follow-up studies have shown that OWHTO is a safe and effective surgical procedure.However,with the increasing awareness of OWHTO,its related complications have been gradually reported,among which problems such as hinge fractures,non-healing/delayed healing of the osteotomy gap,poor force line correction,and increased posterior tibial slope are relatively more frequently reported.Meanwhile,some studies have claimed that patellofemoral joint-related complications can occur after OWHTO,with reduced patellar position and altered patellofemoral joint contact stress,thus accelerating patellofemoral joint cartilage degeneration and causing symptoms such as anterior knee pain,patellar instability,and patellofemoral joint dysfunction,but there are relatively few studies on this issue and no definitive conclusion.Based on this,this study investigated the effects of OWHTO on the patellar position and patellofemoral articular cartilage through a retrospective analysis,in order to provide a clinical basis for the treatment of patients who need to undergo OWHTO.Methods:Forty-six patients admitted to the Department of Orthopaedics of The First Affiliated Hospital of Kunming Medical University for inversion knee osteoarthritis between January 2019 and October 2021,who underwent knee arthroscopic exploration and cleanup combined with medial opening wedge tibial high osteotomy were initially included as study subjects,and later 5 patients were excluded due to exclusion criteria(2 cases of secondary surgery only to remove the internal fixation device without arthroscopic exploration of the knee,1 case of postoperative history of knee trauma on the operated side,and 2 cases of postoperative missed follow-up),41 patients were included finally,including 7 men with 8 knees and 34 women with 38 knees,with a mean age of(54.83±6.38)years.All patients in the group were followed up for 13 to 30 months,with a mean of(22.22±4.61)months and were recommended to have the internal fixation device removed and the knee arthroscopically examined after the osteotomy healed.The Blackbume-Peel Index(BPI)and the posterior tibial slope(PTS)were used to evaluate the changes of patellar height and PTS between the initial and secondary surgery;the Iwano patellofemoral imaging classification and the International cartilage repair society(ICRS)cartilage injury classification were used to evaluate the cartilage degeneration of the patellofemoral joint between the initial and secondary surgery;the visual analogue scale(VAS)and the Kujala patellofemoral score were used to evaluate the pain and function of the knee and patellofemoral joint between the initial and secondary surgery.Results:The mean body mass index(BMI)of the 41 patients finally enrolled was(22.01±2.32)kg/m~2,and the mean preoperative hip-knee-ankle angle(HKA)was(7.15±1.49)°,the mean postoperative HKA was(-3.02±1.45)°,and the mean corrected angleΔHKA was(10.17±2.23)°.BPI decreased from(1.07±0.24)at the initial surgery to(0.85±0.18)at the secondary surgery,and the difference was significant in statistic(P<0.001);PTS increased from(8.85±3.39)°at the initial surgery to(10.50±3.23)°at the secondary surgery,and the difference was significant in statistic(P<0.001).Meanwhile,in this study,the correlation analysis was made between the change in PTS of primary surgery and secondary surgery,ΔPTS,and the change in BPI,ΔBPI,with the meanΔPTS of(1.65±2.17)°and the meanΔBPI of(0.22±0.13),after correlation analysis showed that there was a positive correlation betweenΔPTS andΔBPI,r=0.345,P=0.019(<0.05).The Iwano patellofemoral joint imaging grade in this group changed from 32 cases of grade I,13 cases of grade II,1case of grade III,and 0 cases of grade IV in the initial surgery to 29 cases of grade I,13 cases of grade II,4 cases of grade III,and 0 cases of grade IV in the secondary surgery;the ICRS grade changed from 25 cases of grade I,18 cases of grade II,3cases of grade III,and 0 cases of grade IV in the initial surgery to 20 cases of grade I,19 cases of grade II,5 cases of grade III,and 2 cases of grade IV in the secondary surgery,there was a trend of progression in both grades of secondary surgery compared to primary surgery,but no statistical significance after statistical analysis(P>0.05).The Kujala patellofemoral score increased from(5.63±5.45)at the initial surgery to(75.66±4.66)at second surgery,and the difference was significant in statistic(P<0.001);the VAS score decreased from(7.17±0.95)at the initial surgery to(4.96±0.94)at the second surgery,and the difference was significant in statistic(P<0.001);Conclusions:1.Open wedge tibial high osteotomy leads to a reduction in patellar position and an increase in posterior tibial slope,and there is a weak correlation between the both,suggesting that the greater the increase in posterior tibial slope,the greater the reduction in patellar position;2.Open wedge tibial high osteotomy has a small effect on patellofemoral cartilage degeneration in the short term;3.Open wedge tibial high osteotomy can be considered a safe and effective surgery for the treatment of patients with symptomatic inversion knee osteoarthritis,even if mild to moderate patellofemoral arthritis is present preoperatively.Although progress in patellofemoral cartilage degeneration was observed 2 years after surgery,the VAS score and Kujala score improved more significantly in the short term compared with the preoperative period,so the impact on the recent clinical outcome was small.