A Series Of Basic And Clinical Studies On Patellar Instability

Part One Changes in tibiofemoral joint morphology in patients withpatellar instability accompanied by trochlear dysplasiaObjective: Trochlear dysplasia(TD)often leads to anatomic variations of the knee.The first purpose of this part was to analysis the changes of tibiofemoral joint anatomical morphology in patients with patellar instability accompanied by trochlear dysplasia.The second purpose of this part was to explore the correlation between femoral anteversion and morphology of distal femoral condyle in patellar instability with trochlear dysplasia.Methods: Ninety patients(90 knees)with patellar instability and trochlear dysplasia who had undergone surgeries and 53 patients(55 knees)with well-developed patellofemoral joint from January 2015 to June 2019 were retrospectively analyzed.All patients underwent CT scans of lower limb to assess the femoral anteversion and morphology of tiobiofemoral joint.Two researchers evaluated the posterior tibial slope(PTS),distal femoral rotation and femoral anteversion between the two groups.The independent Student's t-test was used to evaluate the statistical signifcance of variables.Representative parameters of distal condyle length were measured using the ratio of Bi-anterior condyle,Bi-posterior condyle,Bi-condyle,anterolateral condyle,anteromedial condyle with reference to the anatomical epicondylar axis.Pearson correlation coefficient was carried out to explore the correlation between the femoral anteversion(torision)and condylar parameters.Results: The first part of the results showed that the study group had a smaller lateral PTS(5.23±2.65)than the control group(6.98±2.89)(P<0.01),while the medial PTS showed consistent values between the control and the study group(non-signifcant).The study group had bigger external rotation of the distal femur(6.73±1.91)compared to the control group(4.03±1.33)(P<0.01).In addition,the femoral anteversion in the study group(27.53±10.22)was increased compared to the control group(12.22±5.39)(P<0.01).The second part of the results showed that the femoral torsion had shown significant correlation with distal condylar morphology.The femoral anteversion angle was significantly correlated with the ratio of the bi-anterior condyle(r=0.355,p<0.05),the ratio of the anterolateral condyle and lateral condyle(r=0.309,p<0.05).The PFA-AEA angle is also significantly correlated with the ratio of the bi-anterior condyle(r=0.319,p<0.05),the ratio of the anterolateral condyle and lateral condyle(r=0.261,p<0.05).Besides,the Bi-anterior condyle ratio showed a significant correlation with the Bi-posterior condyle ratio(r=-0.324,p<0.05).Conclusions: Patients with patellar instability accompanied by trochlear dysplasia had flatter lateral PTS compared to those without TD,but there were no di erences in the medial PTS between the two groups.Patients with TD had bigger distal femoral rotation.The femoral anteversion in patients with TD was bigger than those without TD.What's more,the greater femoral anteversion correlated with a relatively protruding anterolateral condyle and the shorter posterolateral condyle compared with the medial condyle.And the deformity of the anterior condyle and posterior condyle was prone to be a combined deformity rather than existed in isolation.Part Two Changes in cartilage and subchondral bone in a growing rabbitexperimental model of developmental trochlear dysplasia ofthe kneeObjective: The purpose of this part was to investigate the changes of femoral trochlear morphology,surface cartilage and subchondral bone of femoral trochlea after patellar lateral dislocation in growing rabbits.Methods: Forty-eight one-month-old rabbits(96 knees)were included in this study.All the knees were divided into experimental group(left knees)and control group(right knees).Surgical release of medial retinaculum was performed in the experimental group to establish lateral patellar dislocation model.Distal femoral tissues were collected at 4,8,12 and 24-week time after surgery,respectively.The anatomical structures of the trochlear cartilage and subchondral bone were studied by gross examination and histological observation.Mricro-CT was used to measure the medial,central and lateral trochlear height,sulcus angle,and lateral and medial trochlear slope,which were used to analysis the trochlear morphology,and then bone volume fraction(BV/TV),trabecular number(Tb.N),trabecular spacing(Tb.Sp),trabecular thickness(Tb.Th)and bone mineral density(BMD)were used to evaluate the microarchitectural structure of subchondrol bone.Subsequently,we performed western blot and RT-PCR analysis to detect the expression of TRPV4,collagen II and MMP-13 in cartilage,respectively.Results: Four weeks after patellar dislocation,bone loss was observed in the subchondral bone of trochlear,accompanied by an increased number of osteoclasts,while no significant changes in the surface cartilage.From 8 weeks after patellar dislocation,the trochlear dysplasia was appeared,accompanied by slightly degeneration of cartilage.Twenty-four weeks after surgery,the central trochlear height and sulcus angles were greater compared to control group,and the BV/TV,Tb.Th,Tb.N and BMD were decreased and Tb.Sp was increased in both medial and lateral condyle compared with its control knees,accompanied by decreased expression of mechanically sensitive TRPV4 and collagen II,and increased expression of MMP-13.Conclusion: This part proved that patellar dislocation model could be successfully achieved by our method,and subsequent trochlear dysplasia can be caused by patellar dislocation in growing rabbits,accompanied by significant subchondral bone loss.In addition,this part also indentified that early degeneration of cartilage could be caused by patellar dislocation and aggravated with time,accompanied by increased MMP-13,but decreased TRPV4 and collagen II.Part Three Patient-Reported Outcomes and Risk Factors withPatellofemoral Arthroplasty for Isolated PatellofemoralOsteoarthritisObjective: Patellofemoral arthroplasty(PFA)is acknowledged as the method for the treatment of isolated patellofemoral osteoarthritis(PFOA).The assessment methods for the postoperative results of joint replacement often focus on objective outcomes of patients,which often ignore the subjective feelings of patients themselves and may cause differences in postoperative focus between patients and surgeons.The aim of this study was to evaluate the short-term patient-reported outcomes(PROs)of PFA and identify how short-term PROs following PFA may be influenced by the risk factors.Methods: A retrospective analysis was performed,including patients undergoing PFA between January 2016 and January 2020.Pre-and postoperative patient-reported outcome methods(PROMs)included the OKS and Kujala score.Univariate and multivariate statistical analyses were performed to assess influencing factors of less improvement of PROs including the demographic factors(gender,age,BMI,smoking,opioid usage and duration of symptoms),surgical factors(concomitant surgery)and imaging factors(trochlear dysplasia,patellar height,the degree of PFOA).Results: A total of 46 PFAs were analyzed with a mean follow-up of 37±7 months.The mean age at surgery was 61.1±7.7 years.Patients showed significant improvement in all PROs(p < 0.001).Absence of trochlear dysplasia showed less improvement in OKS(p=0.038).Longer duration of symptoms(?1 years)had a greater mean improvement in OKS and Kujala score(p=0.011,p=0.000).Patients with patella alta(CDI?1.3)showed less improvement in both OKS and Kujala score(p=0.000,p=0.002).Conclusion: PFA would appear to be a safe and efficient surgery with good PROs.Three predictive factors for less improvement of PROs were identified: patella alta with a CDI?1.3,duration of preoperative symptoms?1 years and absence of trochlear dysplasia before surgery.