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1.
Cureus ; 15(6): e41163, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37525807

ABSTRACT

BACKGROUND: Salvage procedures for distal radioulnar joint (DRUJ) arthritis, like the Darrach or Sauvé-Kapandji (S-K) procedures, often result in extensor tendon ruptures at the ulnar stump. Radioulnar instability is considered the underlying cause and stump stabilization techniques are employed. This study investigated radioulnar instability, extensor tendon irritation, and the effectiveness of stump stabilization techniques following salvage procedures. METHODS: Six upper limbs from three cadavers were used. Forearm rotation was measured using magnetic position sensors to assess radial movement. The Darrach procedure was performed on two limbs, comparing radial motion ranges for different ulnar osteotomy positions. The risk of tendon rupture was assessed with applied weight. The S-K procedure was performed on four limbs, evaluating stump stabilization techniques and radial movement distance underweight. RESULTS: Proximal osteotomy positions increased radial motion range. Extensor tendon irritation occurred when the load was applied to the volar and ulnar sides, particularly with a pronated forearm. Stump stabilization techniques did not significantly contribute to ulnar stump stabilization. CONCLUSIONS: Proximal ulnar osteotomy positions in DRUJ salvage procedures led to increased radioulnar instability and potential complications. Load application on the volar and ulnar sides, especially in a pronated forearm, increased the risk of tendon rupture. Stump stabilization techniques showed limited utility in stabilizing the ulnar stump or reducing complications. These findings can inform strategies for minimizing complications in DRUJ salvage procedures.

2.
Bone ; 132: 115212, 2020 03.
Article in English | MEDLINE | ID: mdl-31891786

ABSTRACT

As fractures heal, immature callus formed in the hematoma is calcified by osteoblasts and altered to mature bone. Although the bone strength in the fracture-healing process cannot be objectively measured in clinical settings, bone strength can be predicted by specimen-specific finite element modeling (FEM) of quantitative computed tomography (qCT) scans. FEM predictions of callus strength would enable an objective treatment plan. The present study establishes an equation that converts material properties to bone density and proposes a specimen-specific FEM. In 10 male New Zealand white rabbits, a 10-mm long bone defect was created in the center of the femur and fixed by an external fixator. The callus formed in the defect was extracted after 3-6 weeks, and formed into a (5 × 5 × 5 mm3) cube. The bone density measured by qCT was related to the Young's modulus and the yield stress measured with a mechanical tester. For validation, a 10-mm long bone defect was created in the central femurs of another six New Zealand white rabbits, and fixed by an external fixator. At 3, 4, and 5 weeks, the femur was removed and subjected to Computed tomography (CT) scanning and mechanical testing. A specimen-specific finite element model was created from the CT data. Finally, the bone strength was measured and compared with the experimental value. The bone mineral density σ was significantly and nonlinearly correlated with both the Young's modulus E and the yield stress σ. The material-property conversion equations were E = 0.2391e8.00ρ and ρ = 30.49σ2.41. Moreover, the experimental bone strength was significantly linearly correlated with the prospective FEM. We demonstrated the Young's moduli and yield stresses for different bone densities, enabling a FEM of the bone-healing process. An FEM based on these material properties is expected to yield objective clinical judgment criteria.


Subject(s)
Bone Density , Bony Callus , Animals , Biomechanical Phenomena , Bony Callus/diagnostic imaging , Elastic Modulus , Finite Element Analysis , Male , Prospective Studies , Rabbits , Stress, Mechanical
3.
Clin Biomech (Bristol, Avon) ; 72: 136-140, 2020 02.
Article in English | MEDLINE | ID: mdl-31865255

ABSTRACT

BACKGROUND: A1 pulley stretching is recognized as a clinically beneficial treatment for trigger finger. It is thought to lead to an increase in the cross-sectional area of the A1 pulley luminal region, thus improving trigger finger symptoms. The purpose of the present study was thus to evaluate the resultant forces during stretching that increase the CSA of the A1 pulley luminal region using fresh-frozen cadavers. METHODS: Using seven fingers from three fresh-frozen cadavers to replicate A1 pulley stretching, we investigated the resultant forces during stretching that increase the cross-sectional area of the A1 pulley luminal region. The traction forces of the flexor digitorum profundus tendons were increased in steps to 150 N, and the cross-sectional area and height of the A1 pulley luminal region were measured using ultrasonography. FINDINGS: The cross-sectional area of the A1 pulley luminal region increased with step-wise increases in the flexor digitorum profundus traction. On average, the cross-sectional area and height of the A1 pulley luminal region showed increases of 31.4% and 43.6%, respectively, compared to the unloaded condition. INTERPRETATION: These results confirmed that A1 pulley stretching increases the cross-sectional area of the A1 pulley luminal region. A1 pulley stretching has the potential to reduce the severity of trigger finger in patients facing surgery.


Subject(s)
Fingers , Mechanical Phenomena , Tendons , Traction/methods , Trigger Finger Disorder/surgery , Adult , Cadaver , Female , Humans , Male , Middle Aged , Tendons/surgery , Trigger Finger Disorder/diagnostic imaging , Ultrasonography
4.
J Med Case Rep ; 9: 7, 2015 Jan 12.
Article in English | MEDLINE | ID: mdl-25582755

ABSTRACT

INTRODUCTION: Epidermoid cysts are known as embryonic or acquired ectopic aberrations of the ectoderm. To the best of our knowledge, there are only a few reports of elderly onset intramedullary epidermoid cysts. We report a case of elderly onset intramedullary epidermoid cyst at the conus medullaris. CASE PRESENTATION: A 63-year-old Japanese woman working as a farmer presented with slowly progressive gait disturbance and voiding dysfunction. A magnetic resonance imaging scan revealed an intramedullary mass lesion at L1 to L3. We diagnosed the lesion as an intramedullary spinal cord tumor. A laminectomy was performed at the level of Th12 to L3. Upon spinal cord dissection, a yellowish milky exudation erupted from the cystic lesion. We resected white cartilage-like pieces from the cystic cavity. Because the wall of the cystic lesion tightly adhered to the spinal cord parenchyma, we abandoned complete resection of the cyst wall. The pathological diagnosis was an epidermoid cyst. CONCLUSIONS: We propose that evacuation of the cyst contents is preferable, especially in cases with elderly onset and congenital origin.


Subject(s)
Epidermal Cyst/diagnosis , Gait Disorders, Neurologic/pathology , Laminectomy/methods , Spinal Cord Diseases/diagnosis , Spinal Cord/pathology , Epidermal Cyst/pathology , Epidermal Cyst/surgery , Female , Gait Disorders, Neurologic/etiology , Gait Disorders, Neurologic/surgery , Humans , Magnetic Resonance Imaging , Middle Aged , Spinal Cord Diseases/pathology , Spinal Cord Diseases/surgery , Treatment Outcome
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