Manual Therapy 20 (2015) 445e450 Contents lists available at ScienceDirect Manual Therapy journal homepage: www.elsevier.com/math Original article An anatomical and histological study of the structures surrounding the proximal attachment of the hamstring muscles * Albert Perez-Bellmunt a, 1, Maribel Miguel-Perez b, , 1, Marc Blasi Brugue b, c, Juan Blasi Cabús d, Martí Casals a, e, Carlo Martinoli f, Raija Kuisma g a Basic Sciences Department, Universitat Internacional de Catalunya, Spain b Unit of Human Anatomy and Embriology, Department of Pathology and Experimental Therapeutics, Faculty of Medicine, Campus de Bellvitge, University of Barcelona, Spain c Department of Fundamental Care and Medical-Surgical Nursing, University School of Nursing, University of Barcelona, Spain d Histology Unit, Department of Pathology and Experimental Therapeutics, Faculty of Medicine, Campus de Bellvitge, University of Barcelona, Spain e CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain f Cattedra di Radiologia “R”eDICMI, Universita di Genova, Genoa, Italy g School of Health Sciences, University of Brighton, UK article info abstract Article history: Introduction: The proximal attachment of hamstring muscles has a very high incidence of injuries due to Received 16 July 2013 a wide number of factors and its morphology may be one of the underlying factors as scientific literature Received in revised form points out. The connective tissue component of the attachment of hamstring muscles is not well known. 7 November 2014 For this reason the aim of this study is to describe the anatomy and histology surrounding the proximal Accepted 11 November 2014 attachment of the hamstring muscles (PAHM) and its direct anatomic relations. Methods: Forty-eight cryopreserved lower limbs have sequentially been studied by means of dissection, Keywords: anatomical sections and histology. Hamstring proximal attachment Hamstring injury Results: All specimens studied presented an annular connective tissue structure that resembles a reti- Retinaculum naculum, which covers and adapts to the attachment of hamstring muscles on the ischial tuberosity. Fascia Conclusion: The results show how this retinaculum is continuous with the long head of biceps femoris muscle, however there is a layer of loose connective tissue between the retinaculum and the semite- ndinosus muscle. Furthermore, this structure receives expansions of the anterior epimysium of the gluteus maximus muscle (GIM). © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Hamstrings injuries are common in many sports, especially when rapid acceleration and running at maximum speed are “The hamstrings” is a colloquial term used for the muscles found needed (Hoskins and Pollard, 2005; Opar et al., 2012). As a per- in the posterior compartment of the thigh. They include the biceps centage of total hamstring injuries, the prevalences are 12%e16% in femoris, the semitendinosus and the semimembranosus muscles. football (soccer) (Arnason et al., 1996; Hawkins et al., 2001) and 11% The ischial tuberosity is the proximal attachment of the hamstring in cricket (Stretch, 2003). In addition to their high incidence, these muscles (PAHM) except for the short head of the biceps femoris, injuries are also associated with a high recurrence rate (Arnason which arises from the linea aspera of the femur. These muscles are et al., 1996; Woods et al., 2004); for example, football has a rate, hip extensors and knee flexors (Beltran et al., 2012) and are key of approximately 16% (Ekstrand et al., 2011). Injury severities range muscles for gait and running. from a minor inflammation to a muscle strains (Opar et al., 2012), and rehabilitation can be prolonged and complicated by the high incidence of recurrence (Orchard and Best, 2002; Woods et al., * Corresponding author. Unit of Human Anatomy and Embriology, Department of 2004). Pathology and Experimental Therapeutics, Faculty of Medicine, Campus de Bell- Hamstrings injuries may affect any of the components of the vitge, University of Barcelona, C/Feixa Llarga s/n 08907 L'Hospitalet de Llobregat, muscle group (Garrett et al., 1989; Pomeranz and Heidt, 1993; BCN, Spain. Tel.: þ34 93 4020170. E-mail address: [email protected] (M. Miguel-Perez). Woodley and Mercer, 2005). However the PAHM or the proximal 1 A. Perez-Bellmunt and M. Miguel-Perez contributed equally to this work. muscle-tendon-bone unit is the site most frequently injured (De http://dx.doi.org/10.1016/j.math.2014.11.005 1356-689X/© 2014 Elsevier Ltd. All rights reserved. 446 A. Perez-Bellmunt et al. / Manual Therapy 20 (2015) 445e450 Smet and Best, 2000; Askling et al., 2007b). Moreover, the biceps eight specimens in the frontal plane and six specimens in the femoris is consistently the most commonly injured of the three sagittal plane. We took photographs during these procedures using muscles (Thelen et al., 2005; Askling et al., 2007a; Sato et al., 2012). a digital camera (CANON 911). A multifactorial etiology has been proposed based on the biomechanics and morphology of the PAHM (Beltran et al., 2012; 2.2. Histological study Sato et al., 2012), but the evidence is often inconclusive or contra- dictory (Orchard and Best, 2002). In addition, it is possible that the We obtained six connective tissue samples from the proximal biceps femoris muscle is predisposed to injury due to its myofascial attachment of the hamstring tendon at the ischial tuberosity and attachments (Hoskins and Pollard, 2005). It is equally important to the gluteus maximus muscle (sample size 2.5 Â 1.5 cm) from study the anatomy and morphology of the connective tissue around previously dissected specimens (3 males and 3 females). All the PAHM given the argument that a better knowledge could samples were immediately fixed using a 4% formaldehyde solu- improve our understanding of hamstring injuries and improve the tion and embedded in paraffin before obtaining 7 mmthickslices available treatments (Culav et al., 1999; Sato et al., 2012). However, for histological examination. The slices were stained with no published studies have described the fascial elements or con- hematoxylin-eosin to observe the structure and distribution of nective tissue around the PAHM. the connective tissue of interest. The thicknesses of the dense This study aims to examine the anatomy and histology of the connective tissue samples were recorded at different points in PAHM in detail, specifically its surrounding connective and fascial the histological slice. All slices were analyzed and measured tissue, and its direct anatomic relations in order to broaden our using a Leica DMD108 digital micro-imaging instrument (Leica existing knowledge of the anatomy in this region. Microsystems). 2. Material and methods 3. Results We examined 48 cryopreserved hemipelvis and their corre- sponding thighs; 11 males and 13 females, with a mean age of 78 3.1. Dissection study years (range 58e88). The body donor program of the Faculty of Medicine (Bellvitge Science Heath Campus), University of Barce- Stratigraphic dissection of the gluteal and posterior thigh lona, provided all specimens. None of the cadaveric specimens used exposed the superficial fascia (subcutaneous adipose tissue) and for this study had evidence of traumatic injuries or surgical scars. the deep fascia underneath. The deep fascia surrounding the We assigned each specimen a number (1e48) as it was processed. gluteus maximus muscle, the gluteal fascia, continued distally as The analysis involved two stages: an anatomical study followed by the fascia lata. The latter covered and compartmentalized the thigh a histological study. muscles. The hamstring muscles were present in the posterior compartment. 2.1. Anatomical study The gluteus maximus muscle also had its own fascia, an epimysium which was a continuation of the connective tissue that 2.1.1. Dissection procedure embedded the different muscle fascicles (the perimysium and We dissected 26 bilateral lower limbs from 13 cadavers (4 males endomysium) and emerged on the anterior aspect of the gluteus and 9 females) in the prone position. Dissection proceeded in a maximus muscle. At this point, the epimysium of the gluteus proximal distal direction, from the gluteal to the popliteal region. maximus was continuous with the perineal fascia. Two longitudinal incisions were performed. The first was made The gluteus maximus muscle covered the ischial tuberosity and through the midline of the lumbar and sacral spine, superficial to 4e6 cm of the PAHM. When detaching the gluteus maximus spinous process and the median sacral crest of the sacrum. The muscle, a fascial expansion was observed from its anterior aspect second incision passed from the posterosuperior aspect of the thigh that expanded to the PAHM (Fig. 1). Laterally, the fascial expansion to the popliteal region. Three transverse incisions were then per- split to form a canal that surrounded the sciatic nerve and the formed. The highest incision was made at the level of iliac crest, the posterior femoral cutaneous nerve (Fig. 1). middle incision at the level of the gluteal sulcus and the lowest During detailed dissection, we observed the attachment of incision at the level of the femoral condyles. The skin and subcu- the sacrotuberous ligament on the proximal portion of the taneous adipose tissue of the superficial fascia were removed in ischial tuberosity together with, the PAHM more distally. Su- layers, exposing the deep gluteal fascia and the fascia lata, which perficial to these attachments, an annular-like shape