The adult human pubic symphysis: a systematic review

Abstract

The pubic symphysis is a unique joint consisting of a fibrocartilaginous disc sandwiched between the articular surfaces of the pubic bones. It resists tensile, shearing and compressive forces and is capable of a small amount of movement under physiological conditions in most adults (up to 2 mm shift and 1° rotation). During pregnancy, circulating hormones such as relaxin induce resorption of the symphyseal margins and structural changes in the fibrocartilaginous disc, increasing symphyseal width and mobility. This systematic review of the English, German and French literature focuses on the normal anatomy of the adult human pubic symphysis. Although scientific studies of the joint have yielded useful descriptive data, comparison of results is hampered by imprecise methodology and/or poorly controlled studies. Several aspects of the anatomy of the pubic symphysis remain unknown or unclear: the precise attachments of surrounding ligaments and muscles; the arrangement of connective tissue fibres within the interpubic disc and the origin, structure and function of its associated interpubic cleft; the biomechanical consequences of sexual dimorphism; potential ethnic variations in morphology; and its precise innervation and blood supply. These deficiencies hinder our understanding of the normal form and function of the joint, which is particularly relevant when attempting to understand the mechanisms underlying pregnancy-related pubic symphyseal pain, a neglected and relatively common cause of pubic pain. A better understanding of the normal anatomy of the human pubic symphysis should improve our understanding of such problems and contribute to better treatments for patients suffering from symphyseal pain and dysfunction.

Fig. 1

Sections of the pubic symphysis as depicted by William Hunter (1762). (A) Coronal section from a nulliparous female. AA, pubic bone; BB, cartilage; C, interior ‘ligamentous substance’; D, superior pubic ligament; E, inferior pubic ligament. (B) Axial section from a woman with puerperal fever. AA, pubic bone; BB, cartilage; C, interior ‘ligamentous substance’, the anterior pubic ligament that blends with tendinous fibres from adjacent muscle attachments; D, posterior pubic ligament that projects prominently in some subjects. The interpubic cleft is visible in the centre of the joint.

Fig. 2

Search strategy for scientific articles included in the systematic review.

Fig. 3

Coronal T1-weighted magnetic resonance image of the pubic symphysis in a supine 33-year-old woman (anterior view). Note that the joint is asymmetric. B, bladder; AM, adductor muscle group; PB, pubic bone; IPD, interpubic disc.

Fig. 4

Dissection images of the pubic symphysis from an elderly cadaver of unknown parity. (A) Anterior view of the pubic symphysis showing blending of the tendons of rectus abdominis (RA) and pyramidalis (P) with the anterior pubic ligament. Note the decussation of the gracilis (G) tendons. AL, adductor longus. (B) Posterior view of the superior (SPL) and inferior (IPL) pubic ligaments. (C) The left medial pubic surface after bisection of the fibrocartilaginous interpubic disc.

Fig. 5

(A) E12 axial slice through a human female pubic symphysis (W.D. Trotter Anatomy Museum, Department of Anatomy & Structural Biology, University of Otago, Dunedin, New Zealand). (B) Illustration of the key anatomical features in Fig. 5A.

Fig. 6

Sagittal section through the interpubic disc showing the arrangement of collagen fibres within the disc (adapted from Schmidt, 1956).

Fig. 7

Photomicrographs of 5-μm axial sections through a mouse pubic symphysis. (A) Virgin adult female; (B) Multiparous. Haematoxylin & eosin, × 10 magnification. APL, anterior pubic ligament; PPL, posterior pubic ligament; PB, pubic bone; IPD, interpubic disc.