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Isono et al: Tibial Torsion Malalignment in Small Dogs with Medial Patellar Luxation
Veterinary and Comparative Orthopaedics and Traumatology 4, 2025

🔍 Key Findings

  • Proximal Tibia Metatarsal Angle (PTMTA) was significantly increased in dogs with grade 3 and 4 MPL, making it a useful marker for severity.
  • PTMTA strongly correlated with Tibial Torsion Angle (TTA) (r = 0.733) and Crural Rotation Angle (CRA) (r = 0.643), integrating multiple morphological deformities.
  • Grade 4 MPL cases showed significant internal tibial torsion, increased mMPTA, and decreased MDTT/PTW—indicating both rotation and medial displacement.
  • DTMTA was significantly more negative in grade 4, indicating a consistent pattern of internal foot rotation with disease severity.
  • PTMTA can be visually assessed during palpation, offering preoperative utility without CT.
  • Among toy poodles, PTMTA showed significant differences even between grades 3 and normal, suggesting breed-specific severity patterns.
  • Corrective osteotomy may need to address tibial as well as femoral deformities in severe MPL cases with high PTMTA.
  • Younger dogs with grade 4 MPL had more severe deformities, possibly due to early onset or developmental progression.

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← Articles

Isono et al: Tibial Torsion Malalignment in Small Dogs with Medial Patellar Luxation
Veterinary and Comparative Orthopaedics and Traumatology 4, 2025

🔍 Key Findings

  • Proximal Tibia Metatarsal Angle (PTMTA) was significantly increased in dogs with grade 3 and 4 MPL, making it a useful marker for severity.
  • PTMTA strongly correlated with Tibial Torsion Angle (TTA) (r = 0.733) and Crural Rotation Angle (CRA) (r = 0.643), integrating multiple morphological deformities.
  • Grade 4 MPL cases showed significant internal tibial torsion, increased mMPTA, and decreased MDTT/PTW—indicating both rotation and medial displacement.
  • DTMTA was significantly more negative in grade 4, indicating a consistent pattern of internal foot rotation with disease severity.
  • PTMTA can be visually assessed during palpation, offering preoperative utility without CT.
  • Among toy poodles, PTMTA showed significant differences even between grades 3 and normal, suggesting breed-specific severity patterns.
  • Corrective osteotomy may need to address tibial as well as femoral deformities in severe MPL cases with high PTMTA.
  • Younger dogs with grade 4 MPL had more severe deformities, possibly due to early onset or developmental progression.

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Multiple Choice Questions on this study

In Isono 2025 et al., on tibial malalignment in MPL, what clinical advantage does PTMTA provide over TTA in preoperative assessment?

A. It can be assessed visually during palpation
B. PTMTA requires fluoroscopy rather than CT
C. It replaces the need for mMPTA
D. It measures femoral rotation instead
E. It is breed-specific for Yorkshire Terriers

Answer: It can be assessed visually during palpation

Explanation: Unlike TTA, PTMTA can be visually estimated during palpation, improving clinical utility.
In Isono 2025 et al., on tibial malalignment in MPL, which statistical trend was observed in toy poodles with grade 3 MPL?

A. Significantly higher PTMTA compared to normals
B. No difference in tibial parameters
C. Lower mMPTA than controls
D. DTMTA was significantly positive
E. Increased MDTT/PTW ratio

Answer: Significantly higher PTMTA compared to normals

Explanation: Toy poodles with grade 3 MPL had higher PTMTA than normals, indicating breed-specific severity.
In Isono 2025 et al., on tibial malalignment in MPL, which of the following was TRUE regarding the correlation findings?

A. PTMTA had a correlation coefficient of 0.733 with TTA
B. CRA showed no correlation with PTMTA
C. DTMTA was more predictive than PTMTA
D. TTA and CRA were unrelated to MPL severity
E. TTA was more useful than PTMTA for palpation

Answer: PTMTA had a correlation coefficient of 0.733 with TTA

Explanation: PTMTA had a strong positive correlation with TTA (r = 0.733) and CRA (r = 0.643).
In Isono 2025 et al., on tibial malalignment in MPL, which of the following parameters was newly introduced and found to correlate with both TTA and CRA?

A. Proximal Tibia Metatarsal Angle (PTMTA)
B. Mechanical Medial Proximal Tibial Angle (mMPTA)
C. Crural Rotation Angle (CRA)
D. Medial Distance of Tibial Tuberosity (MDTT)
E. Tibial Tuberosity Angle (TTA)

Answer: Proximal Tibia Metatarsal Angle (PTMTA)

Explanation: The PTMTA was a new angle introduced in this study that showed strong correlation with both TTA and CRA.
In Isono 2025 et al., on tibial malalignment in MPL, which finding best characterized grade 4 medial patellar luxation?

A. Significant internal tibial torsion with increased PTMTA and decreased MDTT/PTW
B. Mild external tibial rotation and low CRA
C. No change in PTMTA or TTA compared to controls
D. High MDTT/PTW with normal mMPTA
E. Low PTMTA and DTMTA values

Answer: Significant internal tibial torsion with increased PTMTA and decreased MDTT/PTW

Explanation: Grade 4 MPL cases showed markedly increased PTMTA and torsion with medial displacement of the tibial tuberosity.

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