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Review
. 2014 Nov 17;4(3):333-42.
eCollection 2014 Jul.

The enthesis: a review of the tendon-to-bone insertion

John Apostolakos  1 , Thomas Js Durant  1 , Corey R Dwyer  1 , Ryan P Russell  1 , Jeffrey H Weinreb  1 , Farhang Alaee  1 , Knut Beitzel  2 , Mary Beth McCarthy  1 , Mark P Cote  1 , Augustus D Mazzocca  1
Affiliations
Review

The enthesis: a review of the tendon-to-bone insertion

John Apostolakos et al. Muscles Ligaments Tendons J. .

Abstract

The integration of tendon into bone occurs at a specialized interface known as the enthesis. The fibrous tendon to bone enthesis is established through a structurally continuous gradient from uncalcified tendon to calcified bone. The enthesis exhibits gradients in tissue organization classified into four distinct zones with varying cellular compositions, mechanical properties, and functions in order to facilitate joint movement. Damage to tendinous insertions is common in the field of orthopaedic medicine and often involves surgical intervention that requires the attempted recreation of the natural organization of tendon into bone. The difficulty associated with recreating the distinct organization may account for the surgical challenges associated with reconstruction of damaged insertion sites. These procedures are often associated with high failure rates and consequently require revision procedures. Management of tendinous injuries and reconstruction of the insertion site is becoming a popular topic in the field of orthopaedic medicine.

Keywords: bone; enthesis; reconstruction; tendon.

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Figures

Figure 1.
Figure 1.
Cadaveric image of A) an intact rotator cuff, B) a repaired rotator cuff.
Figure 2.
Figure 2.
Illustrations of A) an intact supraspinatus tendon of the rotator cuff, B) a retracted tear in the supraspinatus tendon of the rotator cuff, C) a repaired tear in the supraspinatus tendon of the rotator cuff.
Figure 3.
Figure 3.
Illustration of the four zones of the enthesis superimposed on a histological section of a mouse supraspinatus. Proteoglycans in tendon, fibrocartilage and calcified fibrocartilage are seen in purple after staining with toluidine blue, which highlights the compositional gradient characteristic of the enthesis.
Figure 4.
Figure 4.
Intraoperative image of a revision open rotator cuff repair. Image portrays augmentation technique utilizing an acellular matrix patch soaked in autologous conditioned plasma (ACP).
See this image and copyright information in PMC

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