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Sullivan et al: Biomechanical Comparison of Spacer Pin Fixation to Two Established Methods of Tibial Tuberosity Transposition Stabilization in Dogs
Veterinary and Comparative Orthopaedics and Traumatology 3, 2025

🔍 Key Findings

  • Spacer pin fixation showed no difference in failure force or stiffness compared to tension band wire (TBW) or 2-pin techniques.
  • All constructs failed under loads >1000 N, exceeding estimated peak quadriceps force in dogs during walking (~240 N).
  • Patellar ligament failure was the most common mode of failure across all groups (5–8 samples per group).
  • Distal tibial crest fractures were seen only in 2-pin and spacer pin groups, not in TBW group, suggesting TBW may protect against crest failure.
  • No failures occurred at pin tracts, possibly due to pin placement within patellar ligament footprint.
  • Spacer pin technique avoids placing pins through the tuberosity, potentially reducing risks of soft tissue complications like tendinopathy or irritation.
  • Use of partial osteotomy with robust distal crest may substitute for TBW without compromising initial mechanical strength.
  • Further in vivo or cyclic loading studies are required, as this cadaveric study tested only acute tensile failure.

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← Articles

Sullivan et al: Biomechanical Comparison of Spacer Pin Fixation to Two Established Methods of Tibial Tuberosity Transposition Stabilization in Dogs
Veterinary and Comparative Orthopaedics and Traumatology 3, 2025

🔍 Key Findings

  • Spacer pin fixation showed no difference in failure force or stiffness compared to tension band wire (TBW) or 2-pin techniques.
  • All constructs failed under loads >1000 N, exceeding estimated peak quadriceps force in dogs during walking (~240 N).
  • Patellar ligament failure was the most common mode of failure across all groups (5–8 samples per group).
  • Distal tibial crest fractures were seen only in 2-pin and spacer pin groups, not in TBW group, suggesting TBW may protect against crest failure.
  • No failures occurred at pin tracts, possibly due to pin placement within patellar ligament footprint.
  • Spacer pin technique avoids placing pins through the tuberosity, potentially reducing risks of soft tissue complications like tendinopathy or irritation.
  • Use of partial osteotomy with robust distal crest may substitute for TBW without compromising initial mechanical strength.
  • Further in vivo or cyclic loading studies are required, as this cadaveric study tested only acute tensile failure.

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Multiple Choice Questions on this study

In Sullivan 2025 et al., on TTT stabilization methods, why should findings be interpreted cautiously for clinical translation?

A. Too small sample size
B. Only TBW method was tested
C. Cadaveric, single-load model used
D. Spacer pin was not radiographed
E. Group allocation was biased

Answer: Cadaveric, single-load model used

Explanation: The study tested acute failure in cadavers, not cyclic loading or clinical healing.
In Sullivan 2025 et al., on TTT stabilization methods, what theoretical advantage does the spacer pin technique offer?

A. Higher stiffness
B. Less implant cost
C. Prevents crest fracture
D. Avoids placing pins through tuberosity
E. Improved healing speed

Answer: Avoids placing pins through tuberosity

Explanation: Avoiding tuberosity pins may reduce risk of soft tissue irritation or fracture.
In Sullivan 2025 et al., on TTT stabilization methods, what was the most common mode of failure across all groups?

A. Pin tract fracture
B. Distal tibial crest fracture
C. Implant loosening
D. Patellar ligament rupture
E. Osteotomy displacement

Answer: Patellar ligament rupture

Explanation: Rupture of the patellar ligament occurred in most samples in all groups.
In Sullivan 2025 et al., on TTT stabilization methods, what biomechanical benefit did the TBW group demonstrate over the others?

A. Higher stiffness only
B. Faster healing
C. Distal crest fracture prevention
D. Lower rate of pin migration
E. Higher ultimate failure force

Answer: Distal crest fracture prevention

Explanation: Only the TBW group had zero crest fractures, unlike the 2-pin and spacer pin groups.
In Sullivan 2025 et al., on TTT stabilization methods, which stabilization method showed significantly different failure force or stiffness?

A. Spacer pin showed superior stiffness
B. TBW was significantly weaker
C. 2-pin was significantly stronger
D. Spacer pin was significantly weaker
E. No significant differences were found

Answer: No significant differences were found

Explanation: All methods showed comparable failure force and stiffness.

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