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Associations between TT-TG distance and rotational and coronal alignment in recurrent patellar dislocation.
Liang Ma1, Qingyu Li1, Jiacheng Wei1
1Department of Orthopaedic Surgery, Hebei Medical University Third Hospital, Shijiazhuang, Hebei, 050051, China.
BMC Musculoskeletal Disorders
|June 23, 2026
Summary
Tibial tubercle-trochlear groove (TT-TG) distance correlates with tibiofemoral rotation in recurrent patellar dislocation patients. This association is stronger in individuals with TT-TG distance less than 20 mm, suggesting rotational alignment is key for treatment planning.
Area of Science:
- Orthopedic surgery
- Biomechanics
- Radiology
Background:
- Recurrent patellar dislocation is a common orthopedic issue often linked to anatomical abnormalities.
- Tibial tubercle-trochlear groove (TT-TG) distance is a key measurement in assessing patellofemoral alignment.
- Understanding the relationship between TT-TG distance and other lower-limb parameters is crucial for effective treatment.
Purpose of the Study:
- To investigate the correlation between the tibial tubercle-trochlear groove (TT-TG) distance and various lower-limb anatomical parameters.
- To analyze these relationships specifically in patients experiencing recurrent patellar dislocation.
Main Methods:
- Review of weight-bearing long-leg radiographs and knee CT scans from 99 patients with recurrent patellar dislocation.
- Classification of trochlear dysplasia using the Dejour version 2 system.
- Measurement of TT-TG distance, coronal alignment (mFTA), and rotational alignment (tibiofemoral rotation, tibial torsion).
- Correlation analysis (Pearson) and multivariable regression were employed to assess associations.
Main Results:
- A significant positive correlation was found between TT-TG distance and tibiofemoral rotation (TFR) overall (r=0.504, P<0.001).
- TFR was significantly higher in patients with TT-TG ≥ 20 mm compared to those with TT-TG < 20 mm.
- In patients with TT-TG < 20 mm, TT-TG distance positively correlated with TFR and tibial torsion; this association was attenuated in patients with TT-TG ≥ 20 mm.
Conclusions:
- TT-TG distance is positively associated with tibiofemoral rotation in recurrent patellar dislocation, but not with coronal alignment.
- The association between TT-TG distance and rotational alignment is more pronounced in patients with smaller TT-TG distances (< 20 mm).
- Interpreting TT-TG distance alongside rotational alignment and trochlear morphology is recommended for personalized treatment planning.
