The Animal Experimental Study Of Femoral Trochlear Groove Changes After Patellectomy And Clinical Study Of Patellofemoral Instability

Part one Changes in cartilage and subchondral bone of femoral trochlear groove after patellectomy in growing rabbitsObjective: Trochlear dysplasia(TD)is a common anatomical abnormality in patellofemoral instability(PI).Patellofemoral stability is associated with the geometry of the femoral trochlear groove.The aim of this experimental study was to explore the effects of patellectomy on the bony and cartilaginous morphology of the trochlear groove in growing rabbits.Methods: Forty-eight 4-week-old New Zealand white rabbits were randomly assigned to two groups.The control group underwent a sham surgical procedure,whereas the patellectomy group underwent patella excision surgery.Half of the rabbits in each group were sacrificed 3 months postoperatively;the rest were sacrificed 6 months postoperatively.Hematoxylin and eosin staining was performed on collected samples.Measurements included the bony and cartilaginous sulcus angles of the trochlear groove.In addition,the thickness of the articular cartilage at the deepest sulcus position(central thickness)and at the mid-position of the medial and lateral facets was measured and compared between groups.Results: Three months after surgery,histological images revealed significant differences between the control group and the patellectomy group in cartilaginous sulcus angle(144.2° ± 1.5° vs.151.9° ± 2.4°,respectively;P < 0.05).No obvious difference in bony sulcus angle was found between the groups.Six months after surgery,significant between-group differences were observed in cartilaginous sulcus angle(136.3° ± 2.5° in control group vs.160.7° ± 3.0° in patellectomy group,P < 0.05)and bony sulcus angle(136.2° ± 2.2° in control group vs.160.4° ± 2.6° in patellectomy group,P < 0.05).However,there were no significant intra-group differences between cartilaginous and bony sulcus angles in either group.Three months after surgery,significant between-group differences were detected in articular cartilage thickness at the three different positions(medial facet: 324.3 ± 14.0 ?m in control group vs.391.7 ± 98.8 ?m in patellectomy group,P < 0.05;central position: 362.1 ± 13.6 ?m in control group vs.730.3 ± 76.8 ?m in patellectomy group,P < 0.05;lateral facet: 324.6 ± 12.7 ?m in control group vs.358.5 ± 38.7 ?m in patellectomy group,P < 0.05).No between-group differences in cartilage thickness were found at 6 months.Conclusions: Abnormal mechanical stress(patellectomy)during a rabbit's development can cause flattening of the femoral trochlear cartilage,followed by changes in the subchondral osseous layer.Abnormal mechanical stress is a crucial factor in the development of trochlear groove dysplasia.Part two Morphological classification of trochlear dysplasia based on three-dimensional modelsObjective: Trochlear dysplasia is a common risk factor for the development of patellofemoral instability(PI).Dejour's classification shows low agreement between conventional radiography and axial magnetic resonance imaging.The present study aimed to evaluate and categorize the true lateral view of three-dimensional(3D)femoral models in patients with TD.Methods: Computed tomography(CT)scans of 96 hip-knee-ankle joints(49 PI patients: 34 female,15 male;mean age 19.1 ± 6.7 years,range 12-41 years)during 2017-2019 were collected and analyzed.A senior orthopedic surgeon classified the true lateral views of femoral 3D models and raw CT images.The crossing-point site and lateral condyle/facet morphology(lateral condyle bump or supratrochlear spur)were the main criteria.Results: TD cases were classified into four types and their frequencies recorded: type 1(7.3%)= crossing-point site in the proximal trochlear area and no lateral condyle bump or supratrochlear spur;type 2(19.8%)= crossing-point site in the proximal trochlear area and presence of a lateral condyle bump or supratrochlear spur;type 3(13.5%)= crossing-point site in the distal trochlear area and no lateral condyle bump or supratrochlear spur;type 4(59.4%)= crossing-point site in the distal trochlear area and presence of lateral condyle bump or supratrochlear spur.Conclusions: The presentation of TD varies greatly among PI patients and can be categorized into four types.This new classification,based on true lateral views of 3D femoral models,may provide relatively reliable guidance when using trochleoplasty to treat TD.Part three Clinical outcomes of closing-and opening-wedge high tibial osteotomy for treatment of anteromedial unicompartmental knee osteoarthritisObjective: To compare long term outcomes of closing-wedge osteotomy(CWO)and opening-wedge osteotomy(OWO)in the treatment of unicompartmental medial osteoarthritis with varus deformity.Methods: This study included 79 patients who underwent high tibial osteotomy(HTO)between 2002 and 2008.Pre-and postoperative radiography and computed tomography were used to evaluate posterior tibial slope,patellar height,the tibiofemoral angle,and the lateral and medial tibiofemoral joint space.Pre-and postoperative severity of arthritis was assessed with the Kellgren-Lawrence grading system.Pre-and postoperative American Knee Society(AKS)score and Lysholm Knee Score(LKS)were determined to evaluate functional outcomes.Results: The duration of follow-up was 86.1 ± 6.2 months.Postoperatively,at the most recent follow-up,there was a slight increase in the size of the medial tibiofemoral joint space after CWO and OWO,which reflected a decrease in stress on the medial compartment and manifested as a significant improvement in the AKS knee and function scores and the LKS.OWO increased the posterior tibial slope as compared to the preoperative value,while CWO reduced the posterior tibial slope.Conclusions: CWO and OWO for HTO resulted in similar functional outcomes.OWO was associated with patella infera and more severe patellofemoral arthritis,while CWO was associated with a greater severity of lateral tibiofemoral arthritis.