Femoral neck fractures. A biomechanical study of a new form of internal fixation using multiple telescoping variable length compression screws

J. B. Neustadt, R. Tronzo, W. J. Hozack, L. Latta

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Biomechanical tests of a new method of fixation for intracapsular hip fractures compared with other types of mechanical fixation were investigated under one specific loading condition. Human femora fixed in formalin were classified by the Singh index for degree of osteoporosis. Specimens of Grade III or less were grouped as osteoporotic, and Grade IV or greater, normal. Both normal and osteoporotic bones were tested. A transverse osteotomy in the subcapital region was fixed by one of two techniques: (1) Asnis screws (AS) or (2) variable length telescoping compression screws (VLCS). Each specimen was roentgenographed after fixation to assess the placement of the devices and reduction. Each femur was held in an angle vise that was placed on rollers on a table mounted on the servohydraulic testing machine. Compression was applied at a constant displacement rate of 10 mm per second to failure. Load and displacement were monitored; specimens were photographed and roentgenographed after failure. In osteoporotic bone, the VLCS provided yield and ultimate load values several times greater than those of the AS. Resistance to combined compression varus loading was significantly higher with the experimental system in osteoporotic bone. In normal bone there was no significant difference between the two systems.

Original languageEnglish (US)
Pages (from-to)181-188
Number of pages8
JournalClinical orthopaedics and related research
Issue number248
StatePublished - Dec 1 1989

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine

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