Optimal bone biopsy route to the proximal femur evaluated by computed tomography-based finite element modeling.

INTRODUCTION: The proximal femur (PF) is one of the most common locations of benign cystic lesions. A fracture after bone biopsy is a rare but severe complication. However, the risk of fracture after biopsy of this lesion has not been well-studied. Computed tomography (CT)-based finite element (FE) modeling estimates the elastic modulus and compressive strength enables fracture prediction. This study investigated strength of PF after biopsy by CT-FE modeling and determined the optimum biopsy level and size. MATERIALS AND METHODS: Six male bone tumor patients' (15-38 years) total femur CT data (slice thickness, 0.8-1.0 mm) of the healthy side were obtained. Three different cylindrical bone defect (BD) diameters (10, 15, and 20 mm) were set on the lateral surface of PF at the following levels: level 1, insertion of the gluteus minimums; level 2, lower end of the greater trochanter (GT); level 3, origin of the vastus lateralis; level 4, center of the lesser trochanter (LT); and level 5, lower end of LT using Mechanical Finder software (version 8.0). Virtual loads were applied with incremental increases of 100 N until fracture occurred and the fracture load (FL) was evaluated. RESULTS: For BD with a diameter of 15 and 20 mm, there was a significant difference in the decrease of the mean FL, with an average of 22% at level 4 and 5, and 33%-44% at levels 3 to 5, respectively. At level 1 and 2, no significant decrease in the mean FL was observed regardless of the diameter of BD. CONCLUSION: Biopsies at level 1 and 2 showed no significant decrease in bone strength. However, biopsy at level 1 may contaminate the GT bursas. Therefore, biopsy at level 2 (lower end of GT) can avoid contamination and minimize the effect on bone strength.

Ligament Reconstruction for Recurrent Anterior Dislocation of the Radial Head.

Isolated recurrent dislocation of the radial head (RH) is very rare, and there have been few reports describing the surgical treatment of this injury. We herein report the case of a 13-year-old girl who underwent ligament reconstruction surgery for isolated recurrent RH dislocation. Her symptoms included pain and apprehension at the elbow with the forearm in supination. A radiologic examination revealed anterior dislocation of the RH with the forearm in supination but complete reduction with the forearm in neutral to pronated positions. Surgical treatment to reconstruct the annular ligament and facilitate the radial collateral ligament was performed using an autograft with internal brace augmentation. At a 12-month follow-up examination, the patient had asymptomatic stability with recovery to sports activities. This case report describes a novel technique for the treatment of a rare pathological condition of the elbow.