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Perez Neto et al: Biomechanical Evaluation of a Femoral Implant for Hip Resurfacing Arthroplasty in Dogs: An Ex Vivo Study
Veterinary and Comparative Orthopaedics and Traumatology 4, 2025

🔍 Key Findings

  • In an ex vivo study of 20 canine femur pairs, implantation of a novel hip resurfacing arthroplasty (HRA) prosthesis reduced maximum load (ML) by 22% and load at collapse (LC) by 27% vs. intact controls (p ≤ 0.05).
  • Displacement at maximum load (DML), displacement at collapse (DC), and stiffness (k) were not significantly different between prosthesis and control groups.
  • Both groups showed similar failure patterns, with 92% failing at the femoral neck.
  • All prosthetic femurs still withstood ~6.2× body weight — exceeding estimated in vivo peak loads (~1.64× BW).
  • Prosthesis positioning (neutral vs valgus) had no significant effect on biomechanical outcomes.
  • Implant design preserved more metaphyseal bone stock than total hip replacement, possibly explaining the smaller load reduction compared to other short-stem prostheses.
  • The press-fit cobalt–chromium design with conical stem allowed full contact and stress distribution over the femoral head/neck.
  • Authors conclude the device has adequate immediate biomechanical strength for clinical use, though long-term in vivo studies are needed.

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← Articles

Perez Neto et al: Biomechanical Evaluation of a Femoral Implant for Hip Resurfacing Arthroplasty in Dogs: An Ex Vivo Study
Veterinary and Comparative Orthopaedics and Traumatology 4, 2025

🔍 Key Findings

  • In an ex vivo study of 20 canine femur pairs, implantation of a novel hip resurfacing arthroplasty (HRA) prosthesis reduced maximum load (ML) by 22% and load at collapse (LC) by 27% vs. intact controls (p ≤ 0.05).
  • Displacement at maximum load (DML), displacement at collapse (DC), and stiffness (k) were not significantly different between prosthesis and control groups.
  • Both groups showed similar failure patterns, with 92% failing at the femoral neck.
  • All prosthetic femurs still withstood ~6.2× body weight — exceeding estimated in vivo peak loads (~1.64× BW).
  • Prosthesis positioning (neutral vs valgus) had no significant effect on biomechanical outcomes.
  • Implant design preserved more metaphyseal bone stock than total hip replacement, possibly explaining the smaller load reduction compared to other short-stem prostheses.
  • The press-fit cobalt–chromium design with conical stem allowed full contact and stress distribution over the femoral head/neck.
  • Authors conclude the device has adequate immediate biomechanical strength for clinical use, though long-term in vivo studies are needed.

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Multiple Choice Questions on this study

In Perez Neto 2025 et al., on hip resurfacing arthroplasty, what was the most common site of failure in both groups?

A. Femoral shaft
B. Femoral neck
C. Trochanteric fossa
D. Acetabular rim
E. Implant–bone interface

Answer: Femoral neck

Explanation: 92% of both prosthetic and control femurs failed at the femoral neck.
In Perez Neto 2025 et al., on hip resurfacing arthroplasty, approximately how many times body weight did prosthetic femurs withstand before failure?

A. 1.6×
B. 3.2×
C. 4.8×
D. 6.2×
E. 8.0×

Answer: 6.2×

Explanation: Despite reduced load tolerance vs. controls, prosthetic femurs still exceeded ~6× body weight capacity.
In Perez Neto 2025 et al., on hip resurfacing arthroplasty, implantation of the prosthesis reduced maximum load by approximately what percentage compared to controls?

A. 10%
B. 15%
C. 22%
D. 27%
E. 35%

Answer: 22%

Explanation: Maximum load was 22% lower in prosthetic femurs versus intact controls.
In Perez Neto 2025 et al., on hip resurfacing arthroplasty, which biomechanical variables were NOT significantly different between prosthetic and intact femurs?

A. Stiffness and displacements
B. Maximum load and stiffness
C. Load at collapse and stiffness
D. Maximum load and displacements
E. All parameters tested

Answer: Stiffness and displacements

Explanation: Stiffness (k), displacement at maximum load, and displacement at collapse were not significantly altered by the prosthesis.
In Perez Neto 2025 et al., on hip resurfacing arthroplasty, what was the impact of implant positioning (neutral vs valgus) on biomechanical performance?

A. Valgus significantly increased stiffness
B. Neutral positioning reduced maximum load
C. Valgus caused earlier collapse
D. No significant effect
E. Neutral increased strain at the stem

Answer: No significant effect

Explanation: Positioning did not significantly influence mechanical outcomes in this ex vivo model.

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