Purpose: The purpose of this study was to meticulously observe the structures around the origin of the long head of the biceps tendon (LHB) in order to propose a method of anatomical superior labrum anterior and posterior repair.
Methods: Twenty-eight shoulders of 16 cadavers with intact LHB origin were macroscopically investigated. Among them, 20 shoulders with an intact superior labrum were additionally observed, to determine whether the anterior edge of LHB on the labrum (point 'A') was anterior to the supraglenoid tubercle. Serial sections vertical to LHB were observed using ordinary light and polarized microscopy in three glenoids and scanning acoustic microscopy in one.
Results: The labrum had a meniscal appearance, and no LHB fibre was sent anterior to the anterior edge of the supraglenoid tubercle. 'A' was not located more posterior than the supraglenoid tubercle. All specimens had the so-called 'the sheet-like structure', in which the portion closer to the LHB origin tends to be stiffer. Fibres of the sheet-like structure ran vertically to LHB.
Conclusion: Fibre orientation and the stiffness of the sheet-like structure suggest its support of LHB. As LHB fibres do not anteriorly cross over 'A', 'A' could be a landmark for the anterior border of LHB, independent from the sheet-like structure. Considering a previous report mentioning that the horizontal mattress suture maintains the meniscus-like structure which might be sufficient for proper motion of the normal superior labrum, the horizontal mattress suture not crossing over 'A' should be recommended from the viewpoint of functional anatomy.