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Acetabular Canal. Part 1.

 

Acetabular Canal. Part 1

S.V. Arkhipov, Independent Researcher, Joensuu, Finland


Abstract

This article describes the space where the ligamentum capitis femoris (LCF) attaches and functions. See also Part 2 and Part 3. 


Elements of the Hip Joint

In the hip joint, articulatio coxae, the acetabulum of the pelvic bone (os coxae) directly contacts the head of the femur (caput femoris). The acetabulum (acetabulum) is a spherical-shaped cavity located on the external surface of the pelvic bone (os coxae), at the junction of the ilium (os ilium), ischium (os ischii), and pubis (os pubis). The component of the acetabulum in the shape of a horseshoe, covered with hyaline cartilage, is called the lunate surface (facies lunata). The acetabular fossa (fossa acetabuli) and the acetabular notch (incisura acetabuli) do not have cartilage coverage. These form a cavity resembling the shape of a tennis racket with a curved plane. At the bottom of the acetabular fossa lies a mass of white adipose tissue – the "fat pad," the ligament of the femoral head (ligamentum capitis femoris, LCF), and synovial folds. The femoral head is the most proximal part of the femur, which transitions below into the cylindrical femoral neck (collum femoris) and then into the body of the femur (corpus femoris). The spherical femoral head is covered with a layer of hyaline cartilage, except for the femoral head fovea (fovea capitis femoris). The head directly contacts the lunate surface of the acetabulum.


Figure 1. Right hip joint, anterior view (from 1908GrayH).


The acetabular labrum (labrum acetabulare), formed by fibrocartilage, attaches to the peripheral edge of the acetabulum and to the transverse ligament of the acetabulum (ligamentum transversum acetabuli). The transverse ligament of the acetabulum connects the edges of the acetabular notch and represents a true intra-articular ligament. Another ligament within the hip joint is the LCF. Its proximal attachment is to the acetabulum, and the distal attachment is to the femoral head. The hip joint is sealed by the joint capsule (capsula articularis), a fibrous membrane in the form of a sleeve. On one side, it attaches to the pelvic bone outside the acetabular labrum, and on the other side, to the proximal end of the femur (extremitas proximalis femoris). The external ligaments of the hip joint are woven into the joint capsule: the iliofemoral ligament (ligamentum iliofemorale), the pubofemoral ligament (ligamentum pubofemorale), the ischiofemoral ligament (ligamentum ischiofemorale), and the orbicular zone (zona orbicularis, Weber's ligament).

The internal surface of the joint capsule, the intra-articular part of the femoral neck, the LCF, the femoral head fovea, and the surface of the acetabulum, which lacks hyaline cartilage, are covered by synovial tissue. The hip joint cavity contains synovial fluid, or "synovia." In our understanding, this is a special component of the joint, a kind of liquid tissue surrounding the intra-articular elements. On the outside of the hip joint there are nerves, vessels, a significant volume of muscles separated by fascial sheets, as well as subcutaneous fat and skin. On the inside, the joint is separated from the muscles, pelvic organs, large vessels and nerves by the pelvic bone.


Figure 2. Transverse ligament and notch of the right acetabulum, inferior view. A, cut surface of the pubic bone. B, same with the ischial bone. C, bone edge between the acetabulum and the obturator foramen, forming the bottom of the acetabular notch. D, fibers of the transverse ligament, originating from the anterior, or pubic, corner of the notch, crossing under fibers (E), originating from the posterior, or ischial, corner, and merging with (F) the acetabular ligament [labrum acetabulare], which continues through the notch, in front of the transverse ligament. G, free space in the notch occupied by adipose tissue, transitioning into the LCF (from 1858HumphryGM).


General Concept of the Acetabular Canal

The transverse ligament of the acetabulum spans across the acetabular notch in the anterior-inferior sector of the acetabulum. T. Schwencke was likely the first to indicate the existence of a hole under the transverse ligament of the acetabulum in his work "Haematologia, sive sanguinis historia" (1743). C. Debierre (1890) called it the "subacetabular" hole (trou sous-cotyloïdien), through which the "interarticular ligament," i.e., LCF, enters the joint. The space between the transverse ligament, the bottom, and the walls of the acetabular notch is filled with adipose tissue (1968РевенкоТА). Modern researchers agree that the transverse ligament of the acetabulum transforms the acetabular notch into a hole (1993ДоэртиМ_ДоэртиД), or rather, into a canal where blood vessels and nerves pass (1946ТонковВ; 1959КорневПГ). Some authors describe this space as a cleft (1996МинеевКП_СтэльмахКК). We proposed to call the said cavity between the head of the femur, which contacts the acetabulum, the "acetabular canal", canalis acetabularis (2004Архипов-БалтийскийСВ). Until now, this formation has received unreasonably little attention in clinical and scientific research.


Figure 3. LCF "entering" the hip joint through the acetabular canal; markings: A – upper part of the femur; a – joint surface; b – greater trochanter; B – ischial bone; C – iliac bone; d – ischial tuberosity; D – acetabulum; 1 – acetabular rim; 2, 3 – interarticular ligament [LCF]; 4, subpubic or obturator membrane (from 1890DebierreC).

In general, the acetabular canal is formed by the femoral head and the acetabular fossa and notch. It is an open, blind-ending slit-like space. Synovial fluid, LCF, white adipose tissue, and folded synovial membrane are visually detected within the acetabular canal. The bony walls of the acetabular canal are covered by soft tissues: hyaline cartilage perichondrium and synovial membrane. This, along with the synovial fluid, reduces the likelihood of LCF abrasion against the bony elements during joint movements.

The works of А.В. Воронцова (1979), Т.Т. Кикачеишвили (1985), В.А. Шильникова (1991), В.А. Неверова & В.А. Шильникова (1991) demonstrated that the head of the femur and the lunate surface of the acetabulum contact in certain zones in the presence of microscopic slit-like spaces, although sometimes having a height of up to 2 mm. This circumstance predetermines the possibility of movement of synovial fluid from the acetabular part of the joint to the cervical part and vice versa. The acetabular labrum helps to separate the medial section of the hip joint from the lateral section. Like a locking ring in mechanisms, it elastically covers the periphery of the femoral head. Due to this, the acetabular part of the joint, and consequently the acetabular canal, is completely sealed. Entry into it is possible only from outside the joint through the acetabular notch, which, as previously mentioned, is filled with adipose tissue (1858HumphryGM; 1968РевенкоТА).


Figure 4. Section of the hip joint; the acetabular canal is indicated by us (from 1836WeberW_WeberE).


At least two arteries enter the acetabular canal. One of them is a continuation of the medial femoral circumflex artery (a. circumflexa femoris medialis) and branches to the acetabulum (r. acetabularis). Another artery is the terminal element of the posterior branch of the obturator artery (r. posterior a. obturatoria), also called the acetabular branch (r. acetabularis) (1963КовановВВ_ТравинАА; 1973СинельниковРД). The latter belongs to the internal iliac artery system, while the former is part of the external iliac artery system. The branch of the a. acetabuli, r. posterior a. obturatoria, is the a. lig. capitis femoris (a. ligamentum teres), which ends as the medial epiphyseal artery (1965ChapchalG; 1984SteinbergME). The LCF artery anastomoses in the femoral head with rr. nutritii capitis proximalis et distalis. Veins and lymphatic vessels exit from the acetabular canal. The veins of the LCF pass through its adipose tissue and are connected with the obturator vein along with the veins of the "fat pad" (1954ГаевскаяЛИ). The lymphatic vessels from the LCF and the part of the capsule immediately adjacent to the transverse ligament of the acetabulum follow the course of the obturator vessels and flow into the hypogastric lymph nodes (1959ГинзбургВВ; 1963КовановВВ_ТравинАА; 1991СоковЛП_РомановМФ). Furthermore, N. Rüdinger (1857) discovered that the obturator nerve, having reached the obturator foramen, gives off a thin trunk that enters the acetabular notch. Penetrating into the hip joint together with the vessels, it branched in the fatty tissue, the transverse ligament of the acetabulum and the LCF (1935ГеселевичАМ; 1981ГолубДМ_БронивицкаяГМ). Б.З. Перлин et al. (1977) found nerve trunks, bundles, myelinated and unmyelinated nerve fibers, nerve plexuses, and receptors, with a significant number of them being mechanoreceptors, in the LCF. These elements, as parts of the LCF, are located together with it in the acetabular canal.


References

Chapchal G. Orthopädische chirurgie und traumatologie der Hüfte. Stuttgart: Ferdinand Enke verlag, 1965.

Debierre C. Traité élémentaire d'anatomie de l'homme (anatomie descriptive et dissection): avec notions d'organogénie et d'embryologie générale. Tome 1. Paris: Félix Alcan, 1890. 

Rüdinger N. Die Gelenknerven des menschlichen Körpers. Erlangen: F. Enke, 1857.

Schwencke T. Haematologia, sive sanguinis historia, experimentis passim superstructa. Accedit observatio anatomica de acetabuli ligamento interno, caput femoris firmante, cum binis tabulis adjectis. Hagae: Jon. Mart. Husson, 1743.

Steinberg ME. Avascular necrosis of the femoral head. In: Surgery of the hip joint ; еd. R.G.Tronzo. 2nd ed. Berlin [etc.]: Springer-Verlag, 1984;2:1-29.

Архипов-Балтийский С.В. Рассуждение о морфомеханике. Норма: В 2-х томах. Калининград, 2004. 

Воронцов АВ. Новый способ эндопротезирования головки бедра. Вестн. хирург. 1979;5:124-125.

Геселевич АМ, Лубоцкий ДН. Пособие к практическим занятиям по топографической анатомии конечностей. Куйбышев, 1941. 

Гинзбург ВВ. Лимфатическая система нижних конечностей человека. Ленинград: Медгиз, 1959.

Голуб ДМ, Бронивицкая ГМ. Развитие тазобедренного сустава и его иннервации у человека. Архив анатом., гистол. и эмбриол. 1981;80(5)47-5.

Доэрти М., Доэрти Дж. Клиническая диагностика болезней суставов: Пер. с англ. Минск: Тивали, 1993. 

Кикачеишвили ТТ. Индивидуальное эндопротезирование при сохранных операциях у больных опухолями костей: Дисс. д-ра мед. наук. Ленинград, 1985.

Кованов ВВ, Травин АА. Хирургическая анатомия нижних конечностей. Москва, 1963. 

Корнев ПГ. Клиника и лечение костно-суставного туберкулеза. Москва: Медгиз, 1959.

Минеев КП, Стэльмах КК. Лечение тяжелых повреждений таза и позвоночника. Ульяновск: Симбирская книга, 1996.

Неверов ВА, Шильников ВА. Обеспечение сохранности суставного хряща вертлужной впадины при эндопротезировании головки бедра. Диагностика и лечение повреждений крупных суставов. Санкт Петербург, 1991:72-75.

Перлин БЗ, Андриеш ВН, Бибикова ЛА. Иннервация тазобедренного сустава человека в норме и при туберкулезном коксите. Кишинев: Штиинца, 1977.

Ревенко ТА. Хирургическое лечение нарушений опороспособности бедра. Киев: Здоров’я, 1968.

Синельников Р.Д. Атлас анатомии человека. В 3-х томах. - Т.2. Москва: Медицина, 1973.

Соков ЛП, Романов МФ. Деформирующие артрозы крупных суставов: учеб. пособие. Москва: Изд-во УДН, 1991.

Тонков В. Анатомия человека. Общая часть. Система органов движения. Т.1. Ленинград: Медгиз, 1946

Шильников В. А. К вопросу об эндопротезировании тазобедренного сустав травматологии. Диагностика и лечение повреждений крупных суставов. Санкт Петербург, 1991.


Keywords

ligamentum capitis femoris, ligamentum teres, ligament of head of femur, acetabular canal, anatomy, attachment


                                                                     

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