TY - JOUR
T1 - The complexity of bony malalignment in patellofemoral disorders
T2 - femoral and tibial torsion, trochlear dysplasia, TT–TG distance, and frontal mechanical axis correlate with each other
AU - Imhoff, Florian B.
AU - Funke, Victor
AU - Muench, Lukas N.
AU - Sauter, Andreas
AU - Englmaier, Maximilian
AU - Woertler, Klaus
AU - Imhoff, Andreas B.
AU - Feucht, Matthias J.
N1 - Publisher Copyright:
© 2019, European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).
PY - 2020/3/1
Y1 - 2020/3/1
N2 - Purpose: Several anatomic risk factors associated with patellofemoral disorders have been described. The purpose of this study was to analyze the relationship between bony parameters commonly used to analyze and define patellofemoral malalignment. Methods: Patients with patellofemoral disorders presenting between 2016 and 2018 who underwent a standardized radiographic workup including conventional radiographs, weight bearing full-leg radiographs, magnetic resonance imaging (MRI) of the knee, and torsional analysis using hip–knee–ankle MRI were initially included. Patients with a history of lower extremity fracture and a history of surgical procedures affecting bony alignment or partial/total arthroplasty were subsequently excluded. Radiographs and MRI of all included patients were analyzed by four independent observers. Parameters of interest were: femoral torsion, tibial torsion, trochlear dysplasia, tibial tuberosity–trochlear groove (TT–TG) distance, and frontal mechanical axis. All parameters were compared between patients with low grade and high grade trochlear dysplasia as well as between female and male patients. Correlation of continuous variables was assessed with the Pearson correlation coefficient. A binary logistic regression model was used for the calculation of odds ratio between different parameters. Interclass correlation coefficients (ICC) were calculated to determine the interobserver reproducibility. Results: A total of 151 patients could be included for detailed analysis. Group comparison revealed that patients with high grade trochlear dysplasia showed significantly higher values for femoral torsion (low grade: 9.8° ± 11.0°, high grade: 16.8° ± 11.5°; p < 0.001) and significantly higher values for TT–TG distance (low grade: 19.0 mm ± 5.0 mm, high grade: 21.9 mm ± 5.4 mm; p = 0.002). No significant difference was found for age, tibial torsion, and frontal mechanical axis. With regard to gender, female patients had higher values for femoral torsion (female: 15.6° ± 11.3°, male: 11.0° ± 12.7°; p = 0.044). The correlation analysis found significant correlation between femoral torsion and tibial torsion (r = 0.244, p = 0.003), femoral torsion and TT–TG distance (r = 0.328, p < 0.001), femoral torsion and frontal mechanical axis (r = 0.291, p < 0.001), and tibial torsion and TT–TG distance (r = 0.182, p = 0.026). Conclusion: Bony malalignment in patients with patellofemoral disorder is a complex problem given the significant correlation between femoral and tibial torsion, trochlear dysplasia, TT–TG distance, and frontal mechanical axis. Advanced imaging to analyze rotational and frontal plane alignment is recommended in patients with trochlear dysplasia and/or increased TT–TG on standard radiographs and knee MRI. Understanding of the bony pathology in patellofemoral disorders is key to improve the therapeutic and surgical decision. Level of evidence: III, retrospective cohort study.
AB - Purpose: Several anatomic risk factors associated with patellofemoral disorders have been described. The purpose of this study was to analyze the relationship between bony parameters commonly used to analyze and define patellofemoral malalignment. Methods: Patients with patellofemoral disorders presenting between 2016 and 2018 who underwent a standardized radiographic workup including conventional radiographs, weight bearing full-leg radiographs, magnetic resonance imaging (MRI) of the knee, and torsional analysis using hip–knee–ankle MRI were initially included. Patients with a history of lower extremity fracture and a history of surgical procedures affecting bony alignment or partial/total arthroplasty were subsequently excluded. Radiographs and MRI of all included patients were analyzed by four independent observers. Parameters of interest were: femoral torsion, tibial torsion, trochlear dysplasia, tibial tuberosity–trochlear groove (TT–TG) distance, and frontal mechanical axis. All parameters were compared between patients with low grade and high grade trochlear dysplasia as well as between female and male patients. Correlation of continuous variables was assessed with the Pearson correlation coefficient. A binary logistic regression model was used for the calculation of odds ratio between different parameters. Interclass correlation coefficients (ICC) were calculated to determine the interobserver reproducibility. Results: A total of 151 patients could be included for detailed analysis. Group comparison revealed that patients with high grade trochlear dysplasia showed significantly higher values for femoral torsion (low grade: 9.8° ± 11.0°, high grade: 16.8° ± 11.5°; p < 0.001) and significantly higher values for TT–TG distance (low grade: 19.0 mm ± 5.0 mm, high grade: 21.9 mm ± 5.4 mm; p = 0.002). No significant difference was found for age, tibial torsion, and frontal mechanical axis. With regard to gender, female patients had higher values for femoral torsion (female: 15.6° ± 11.3°, male: 11.0° ± 12.7°; p = 0.044). The correlation analysis found significant correlation between femoral torsion and tibial torsion (r = 0.244, p = 0.003), femoral torsion and TT–TG distance (r = 0.328, p < 0.001), femoral torsion and frontal mechanical axis (r = 0.291, p < 0.001), and tibial torsion and TT–TG distance (r = 0.182, p = 0.026). Conclusion: Bony malalignment in patients with patellofemoral disorder is a complex problem given the significant correlation between femoral and tibial torsion, trochlear dysplasia, TT–TG distance, and frontal mechanical axis. Advanced imaging to analyze rotational and frontal plane alignment is recommended in patients with trochlear dysplasia and/or increased TT–TG on standard radiographs and knee MRI. Understanding of the bony pathology in patellofemoral disorders is key to improve the therapeutic and surgical decision. Level of evidence: III, retrospective cohort study.
KW - Femoral torsion
KW - Patellofemoral Instability
KW - TT–TG
KW - Tibial torsion
KW - Trochlear dysplasia
UR - http://www.scopus.com/inward/record.url?scp=85067668991&partnerID=8YFLogxK
U2 - 10.1007/s00167-019-05542-y
DO - 10.1007/s00167-019-05542-y
M3 - Article
C2 - 31127313
AN - SCOPUS:85067668991
SN - 0942-2056
VL - 28
SP - 897
EP - 904
JO - Knee Surgery, Sports Traumatology, Arthroscopy
JF - Knee Surgery, Sports Traumatology, Arthroscopy
IS - 3
ER -