The effect of knee flexion and rotation on the tibial tuberosity-trochlear groove distance

Knee Surg Sports Traumatol Arthrosc. 2016 Sep;24(9):2811-2817. doi: 10.1007/s00167-015-3508-9. Epub 2015 Jan 21.


Purpose: The purpose was to measure the effect of flexion and additional rotation of the femur relative to the tibia on the tuberosity-trochlear groove distance (TT-TG) in the same subject in 20 cadaveric knees joint.

Methods: In 20 human adult cadavers, formal fixed knees (age: 81.9 years, SD 12.3; 10 female) CT scans were performed in extension and 30° of flexion as well as in neutral, maximal possible internal (IR), and external rotation (ER). On superimposed CT scan images, TT-TG was measured in each position. TT-TG measurements were correlated in all knee positions.

Results: TT-TG in full extension/neutral rotation was 7.8 mm (SD 3.4, range, 2.4-15.3). TT-TG in full extension and IR was significantly lower, and TT-TG in full extension and ER was significantly higher than in neutral rotation (5.4 ± 2.3 vs. 10.9 ± 4.8 mm; P < 0.001). IR and ER varied between 1.0°-7.6° and 0.2°-9.2°, respectively. TT-TG in 30° flexion/neutral rotation was 3.9 mm (SD 1.8, range, 1.3-7.8), which was significantly lower than in full extension and neutral rotation (P < 0.001). TT-TG in 30° flexion and IR was significantly lower, and TT-TG in 30° flexion and ER was significantly higher than values obtained in neutral rotation (2.7 ± 1.2 vs. 6.5 ± 3.4 mm; P < 0.001). IR and ER in 30° flexion varied between 0.6°-10.7° and 1.9°-13.0°, respectively.

Conclusion: Flexion as well as rotation of the knee joint significantly alters the TT-TG. These results may have wider clinical relevance in assessing TT-TG and further decisions based on it.

Keywords: Cadaver; Femoro-patellar instability; Patellar instability; Rotation; Rotation instability; TT–TG; Tibial tuberosity–trochlear groove distance.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Femur / diagnostic imaging
  • Femur / physiology*
  • Humans
  • Knee Joint / diagnostic imaging
  • Knee Joint / physiology*
  • Male
  • Middle Aged
  • Range of Motion, Articular*
  • Rotation*
  • Tibia / diagnostic imaging
  • Tibia / physiology*
  • Tomography, X-Ray Computed