Humeral head arthroplasty and its ability to restore original humeral head geometry

Fraser Harrold, Carlos Wigderowitz

    Research output: Contribution to journalArticle

    13 Citations (Scopus)

    Abstract

    Background: Modern prosthetic components are designed to enable restoration of proximal humeral morphology, provided that a precise osteotomy of the humeral head at the level of the anatomic neck is performed. To determine whether a simulated osteotomy and replacement arthroplasty with an idealized implant were able to restore original head geometry.

    Materials and methods: A handheld digitizer and surface laser scanner were used to digitize 24 humeri. Computer models were used to simulate an osteotomy, performed at the anterior cartilage-metaphyseal interface, and reconstruct the head with a spherical prosthetic head. The head diameter, radius of curvature, and inclination and retroversion angles were calculated for each specimen and compared with the original humeral head.

    Results: The simulated osteotomy resulted in a 4.8 degrees decrease in inclination (P <.01) and 11.3 degrees increase in retroversion (P <.001). The radius of curvature in the coronal plane was not significantly different (P = .284). However, in the axial plane, the prosthesis was significantly larger than the original head for both head diameter (P <.001) and radius of curvature (P <.05). Discussion: The study suggests that the humeral head is not a perfect segment of a sphere and an osteotomy along the anterior cartilage-metaphyseal interface does not remove only the proximal humeral articular surface. Even with a fully adaptable prosthetic implant, replacement arthroplasty is not able to restore original head geometry.

    Conclusions: Alterations to head geometry with the osteotomy described may alter the line of force through the prosthetic joint, producing eccentric loading at the glenoid, and contribute to early failure.

    Original languageEnglish
    Pages (from-to)115-121
    Number of pages7
    JournalJournal of shoulder and elbow surgery
    Volume22
    Issue number1
    Early online date14 May 2012
    DOIs
    Publication statusPublished - 2013

    Keywords

    • osteotomy
    • humerus
    • RETROVERSION
    • PROSTHETIC DESIGN
    • PROXIMAL HUMERUS
    • TOTAL SHOULDER ARTHROPLASTY
    • REPLACEMENT
    • OSTEOARTHRITIS
    • COMPLICATIONS
    • CONTACT
    • geometry
    • GLENOHUMERAL JOINT
    • ARTICULAR GEOMETRY
    • anatomy
    • Shoulder
    • arthroplasty

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