Priscilla J. Barker

Effects of Tensioning the Lumbar Fasciae on Segmental Stiffness During Flexion and Extension : Young Investigator Award Winner

Study Design. Biomechanical study of unembalmed human lumbar segments. Objective. To investigate the effects of tensioning the lumbar fasciae (transversus abdominis [TrA]) aponeurosis) on segment stiffness during flexion and extension. Summary of Background Data. Animal and human studies suggest that TrA may influence intersegmental movement via tension in the middle and posterior layers of lumbar fasciae (MLF, PLF). Methods. Compressive flexion and extension moments were applied to 17 lumbar segments from 9 unembalmed cadavers with 20 N lateral tension of the TrA aponeurosis during: 1) “static” tests: load was compared when fascial tension was applied during static compressive loads into flexion-extension; 2) “cyclic loading” tests: load, axial displacement, and stiffness were compared during repeated compressive loading cycles into flexion-extension. After testing, the PLF was incised to determine the tension transmitted by each layer. Results. At all segments and loads (<200 N), fascial tension increased resistance to flexion loads by ∼9.5 N. In 15 of 17, fascial tension decreased resistance to extension by ∼6.6 N. Fascial tension during cyclic flexion loading decreased axial displacement by 26% at the onset of loading (0–2 N) and 2% at 450 N (13 of 17). During extension loading, fascial tension increased displacement at the onset of loading (10 of 17) by ∼23% and slightly (1%) decreased displacement at 450 N. Segment stiffness was increased by 6 N/mm in flexion (44% at 25 N) and decreased by 2 N/mm (8% at 25 N) in extension. More than 85% of tension was transmitted through the MLF. Conclusions. Tension on the lumbar fasciae simulating moderate contraction of TrA affects segmental stiffness, particularly toward the neutral zone.

Tensile Transmission Across the Lumbar Fasciae in Unembalmed Cadavers : Effects of Tension to Various Muscular Attachments

Study Design. Traction was applied to muscles attaching to the posterior and middle layers of lumbar fascia (PLF, MLF). Effects on fasciae were determined via tensile force measures and movement of markers. Objectives. To document tensile transmission to the PLF and MLF when traction was applied to latissimus dorsi (LD), gluteus maximus (GM), external and internal oblique (EO, IO), and transversus abdominis (TrA) in unembalmed cadavers. Summary of Background Data. A previous study on embalmed cadavers applied traction to muscle attachments while monitoring fascial movement but did not test TrA or the MLF. Methods. The PLF and MLF were dissected then marked on eight unembalmed cadavers. A strain gauge was inserted through fascia at L3; 10N traction was applied to each muscle attachment while photographs and tension measures were taken. Movement of fascial markers was detected photographically. Fascial widths were also measured. Results. Tension was clearly transmitted to fascial vertebral attachments. Tensile forces and fascial areas affected were highest for traction on LD and TrA in the PLF and for TrA in the MLF. Movement of PLF markers from tension on LD and TrA occurred bilaterally between T12 and S1. Effects from other muscles were variably bilateral, with those from GM and IO occurring below L3 and those from EO occurring above L3. Tensile forces were relatively high in the MLF and its width was less than half that of the PLF. Conclusions. Low levels of tension are effectively transmitted between TrA and the MLF or PLF. Via them, TrA may influence intersegmental movement.

The anatomy of the pubic region revisited: implications for the pathogenesis and clinical management of chronic groin pain in athletes.

Chronic groin pain is a common complaint for athletes participating in sports that involve repetitive sprinting, kicking or twisting movements, such as Australian Rules football, soccer and ice hockey. It is frequently a multifactorial condition that presents a considerable challenge for the treating sports medicine practitioner. To better understand the pathogenesis of chronic groin pain in athletes, a precise anatomical knowledge of the pubic symphysis and surrounding soft tissues is required. Several alternative descriptions of pubic region structures have been proposed. Traditionally, chronic groin pain in athletes has been described in terms of discrete pathology requiring specific intervention. While this clinical reasoning may apply in some cases, a review of anatomical findings indicates the possibility of multiple pathologies coexisting in athletes with chronic groin pain. An appreciation of these alternative descriptions may assist sports medicine practitioners with diagnostic and clinical decision-making processes. The purpose of this literature review is to reappraise the anatomy of the pubic region, considering findings from cadaveric dissection and histology studies, as well as those from diagnostic imaging studies in athletes.

Anatomy and biomechanics of gluteus maximus and the thoracolumbar fascia at the sacroiliac joint.

Biomechanical models predict that recruitment of gluteus maximus (GMax) will exert a compressive force across the sacroiliac joint (SIJ), yet this muscle requires morphologic assessment. The aims of this study were to document GMaxs proximal attachments and assess their capacity to generate forces including compressive force at the SIJ. In 11 embalmed cadaver limbs, attachments of GMax crossing the SIJ were dissected and their fascicle orientation, length and attachment volume documented. The physiological cross‐sectional area (PCSA) of each attachment was calculated along with its estimated maximum force at the SIJ and lumbar spine. GMax fascicles originated from the gluteus medius fascia, ilium, thoracolumbar fascia, erector spinae aponeurosis, sacrum, coccyx, dorsal sacroiliac and sacrotuberous ligaments in all specimens. Their mean fascicle orientation ranged from 32 to 45° below horizontal and mean length from 11 to 18 cm. The mean total PCSA of GMax was 26 cm2 (range 16–36), of which 70% crossed the SIJ. The average maximum force predicted to be generated by GMaxs total attachments crossing each SIJ was 891 N (range 572–1,215), of which 70% (702 N: range 450–1,009) could act perpendicular to the plane of the SIJ. The capacity of GMax to generate an extensor moment at lower lumbar segments was estimated at 4 Nm (range 2–9.5). GMax may generate compressive forces at the SIJ through its bony and fibrous attachments. These may assist effective load transfer between lower limbs and trunk. Clin. Anat. 27:234–240, 2014.

Anatomical and mechanical relationship between the proximal attachment of adductor longus and the distal rectus sheath

The objectives of this study were to investigate the anatomical relationship between the proximal adductor longus (AL) and rectus abdominis muscles and to determine whether unilateral loading of AL results in strain transmission across the anterior pubic symphysis to the contralateral distal rectus sheath. Bilateral dissections were conducted on 10 embalmed cadavers. Strain transfer across the pubic symphysis was examined on seven of these cadavers. An AL contraction was simulated by applying a controlled load in the direction of its proximal tendinous fibers, and the resultant strain in the contralateral distal rectus sheath was measured using a foil‐type surface mounted microstrain gage. Adductor longus attached to the antero‐inferior aspect of the pubis. In 18 of the 20 limbs, the proximal attachment of AL was tendinous on its superficial surface and muscular on its deep surface. The proximal AL tendon was found in most instances to have secondary communications with structures such as the contralateral distal rectus sheath, pubic symphysis anterior capsule, ilio‐inguinal ligament, and contralateral proximal AL tendon. Despite these consistent anatomical observations, strain measured in the contralateral distal rectus sheath upon unilateral loading of the proximal AL varied considerably between cadavers. Measured strain had an average ± 1SD of 0.23 ± 0.43%. The proximal attachment of AL contributes to an anatomical pathway across the anterior pubic symphysis that is likely required to withstand the transmission of large forces during multidirectional athletic activities. This anatomical relationship may be a relevant factor in explaining the apparent vulnerability of the AL and rectus abdominis attachments to injury. Clin. Anat. 2013.

The middle layer of lumbar fascia can transmit tensile forces capable of fracturing the lumbar transverse processes: an experimental study.

BACKGROUND Transversus abdominis and its aponeurotic attachment to the lumbar transverse processes via the middle layer of lumbar fascia are of proposed clinical and biomechanical importance. Moderate traction on these structures (simulating submaximal contraction of transversus abdominis) is reported to influence segmental motion, but their tensile capacity is unknown and the effects of sudden, maximal traction on these attachments and the transverse processes are uncertain. METHODS In 15 embalmed cadaver abdomens, the middle layer of lumbar fascia was isolated, gripped and rapid tension applied in either a lateral or posteroanterior direction (simulating forces that may produce avulsion and traumatic fractures). Peak forces prior to tissue failure were recorded and the gross effects of traction documented. FINDINGS Lumbar transverse process fractures were produced in all specimens; by transverse traction in 50% of tests and posteroanterior force in 80%. In the remainder the middle layer of lumbar fascia was torn. Mean transverse and posteroanterior peak forces reached in the middle layer of lumbar fascia prior to failure were 82 N (range 20-190 N) and 47 N (range 25-70 N), respectively. INTERPRETATION The middle layer of lumbar fascia can transmit substantial tensile forces to lumbar vertebrae, capable of transverse process fracture under experimental conditions. Tensile capacity is likely to be even greater in-vivo. This suggests transversus abdominis and the middle layer of lumbar fascia can strongly influence vertebral motion, should be incorporated in biomechanical models of the spine and considered as potential contributors to transverse process fractures by avulsion.