Background: The location and severity of tibiofemoral bone contusions in magnetic resonance imaging scans in patients with acute non-contact anterior cruciate ligament injuries can reflect the primary mechanisms of anterior cruciate ligament injuries. There has been limited investigation to subdividing the bone contusion model in the medial and lateral directions of the tibial plateau and the femoral condyle.Methods: A retrospective review of 93 consecutive magnetic resonance imaging examinations of patients with acute non-contact anterior cruciate ligament injuries was conducted to identify bone contusions of the knee. The locations and the severity of the bone contusions were determined using magnetic resonance imaging scans for each anatomic site, including the lateral femoral condyle, the lateral tibial plateau, the medial femoral condyle, and the medial tibial plateau. The bone contusions in the lateral-medial and anteriorposterior directions of four anatomical sites were subdivided into six compartments. The severity of the bone contusions was graded on a scale of 1-4. The location and the severity of bone contusions were accessed in the sagittal and coronal planes on the femoral and tibial sides of the knee using the radiology information system. Results:The prevalence of bone contusions on the magnetic resonance imaging scans was as follows: 78.49% on the lateral femoral condyle, 88.17% on the lateral tibial plateau, 49.46% on the medial femoral condyle, and 69.89% on the medial tibial plateau. The most common and severe compartments of the lateral femoral condyle, the lateral tibial plateau, the medial femoral condyle, and the medial tibial plateau were the centrallateral (CL), the posterior-medial (PM), the CL, and the posterior-lateral (PL) compartments, respectively. Conclusions:The location patterns and severity of bone contusions in patients indicated that internal tibial rotation, valgus, and the anterior and lateral translation of the tibia were the primary mechanisms of non-contact anterior cruciate ligament injury.

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Background: The iliotibial band (ITB) has a wide patellar insertion that provides lateral restraint to the patella and maintains the patellofemoral joint's stability. There has been limited investigation into the relationship between patellofemoral malalignment and iliotibial band syndrome (ITBS). Methods:We retrospectively analyzed 47 knees with ITBS by retrieving magnetic resonance imaging (MRI) data collected over an approximately 6-year period from our database. The Insall-Salvati ratio, lateral patellofemoral angle (LPA), lateral patellar tilt (LPT), lateral trochlear length (LTL), angle of the nonweight-bearing facet of the lateral femoral condyle (nwb-LFCA), and the ITB-lateral femoral condyle (IT-LFC) distance were measured on MR images. The knees of 47 age-and gender-matched subjects were enrolled as the normal group.Results: In the ITBS group, over one third (34%, 16/47) of knees had abnormal patellofemoral measurements, including 8 (17%, 8/47) knees with patellar alta, 11 (23.4%, 11/47) knees with an abnormally decreased LPA, and 5 (10.6%, 5/47) knees with an abnormally increased LPT indicating lateral patellar tilt.Moreover, 8 knees had simultaneous combinations of two or three abnormality parameters, and 8 (17%, 8/47) knees presented with superolateral Hoffa's fat pad edema. The Insall-Salvati ratio, LPT, and nwb-LFCA in the ITBS group were significantly higher than those in the normal group (P=0.001, P<0.001, and P<0.001, respectively); the LPA and IT-LFC distances in the ITBS group were significantly lower (P=0.003, P<0.001, respectively) than those in the normal group. There were mild to moderate correlations between the MRI parameters and ITBS (P=0.006, P<0.001, respectively).Conclusions: This study confirmed that a higher position or lateral tilt of the patella and a steeper morphology of the anterior part of the lateral femoral condyle were associated with the development of ITBS, which is helpful in understanding and further exploring the mechanism of ITBS.

Background Some parameters in previous studies did not better reflect the vertical position of the patella relative to the femoral trochlear. This study aimed to assess the value of the most superior point of patella-entrance of femoral trochlea distance ratio (SP-ET index) as a newer index in defining the vertical position of patella relative to the trochlea, correlate it with the Insall–Salvati ratio, and investigate the effect of the new index on patellar cartilage lesions. Methods A total of 99 knees of 77 patients with patellar cartilage lesions were retrospectively analyzed using magnetic resonance imaging (MRI) data. The Insall–Salvati ratio and SP-ET index were measured on MR images. Ninety-nine knees just with meniscus rupture were enrolled as the control group. The two parameters of the patellar cartilage lesions were compared with those of the control group. Results The Insall–Salvati ratio and SP-ET index in the patellar cartilage lesions group were significantly higher than those in the control group (p < 0.001). The SP-ET index showed a moderate positive correlation with the Insall–Salvati ratio (r = 0.307, p < 0.001). Receiver operating characteristic (ROC) analysis showed that the diagnostic efficiency of the SP-ET index was better than that of the Insall–Salvati ratio in patients with patellar cartilage lesions. Conclusion The SP-ET index may be a useful complement parameter to define the vertical position of the patella relative to the femoral trochlear. Increased SP-ET index may be an important risk factor for patellar cartilage lesions.

Background As several studies have detected correlations between patellar and femoral trochlear development, this raises the question of whether patellar shape is associated with trochlear developmental outcomes. Methods Patellar shape and femoral trochlear morphology were retrospectively analyzed in 183 subjects, of whom 61 each were classified as having Wiberg type I, II, and III patellae (groups A, B, and C, respectively). The sulcus angle (SA), lateral trochlea inclination angle (LTA), medial trochlear inclination angle (MTA), lateral facet length (LFL), medial facet length (MFL), lateral trochlear height (LTH), medial trochlear height (MTH), trochlea sulcus height (TH), and lateral-medial trochlear facet distance (TD) were analyzed as a means of evaluating trochlear morphology. Trochlear depth, trochlear condyle asymmetry, and trochlear facet asymmetry were additionally calculated, and differences in trochlear morphology and correlations between trochlear morphology and patellar shape were evaluated. Results The femoral trochlear parameters of patients in group A differed significantly from those of patients in groups B and C. No significant differences between groups B and C were evident. Patellar shape was positively correlated with LTA, MTA, MFL, trochlear condyle asymmetry, and trochlear facet asymmetry, and was negatively correlated with SA. Conclusions These data indicated that patellar shape and trochlear morphology are related to one another,which suggest normalized patella morphology surgery and trochlear surgery are better choices for patients with patella instability. Trial registration Retrospectively registered.