Detailed Anatomy of the Hip Joint
A joint is described as a place where two bones meet. The body has many joints. However, this paper will focus on the hip joint. The hip joint supports the whole body. It is regarded as a ball and socket joint. The hip joint is formed when the femur meets with the bones of the pelvis. These bones are ilium, ischium and pubis. The ilium, ischium and pubis are located at the rear, lower front and above respectively. The thighbone is the one that forms the ball. The hip joint comprises of several structures that assist it to function properly; that is, supporting the body, for example, ligaments and membrane (Foundation for the Advancement in Research in Medicine, Para’s. 1-3). See picture 1.
Bones on the Joint
As shown in picture 2, the hip joint is made up of the pelvic and thigh bone. The thigh bone is the largest bone in the body; it is called the femur. Just above the thigh bone is a rounded projection which enunciates with the pelvis; this portion is usually called the head, it is the one that fits into the concave region forming the ball and socket joint. Other than the rounded protrusion, there is the greater and lesser tronchanters. The muscles associated with the movement of hip joint are usually located at the two tronchanters (Foundation for the Advancement in Research in Medicine, Para. 2-4).
The pelvis has the acetabulum which harbors the head. It also comprises of “girdle bones that are connected at the front by cartilage pad called pubis, and at the back by the lowest fused vertebrae (the sacrum)” (Foundation for the Advancement in Research in Medicine, paras. 4-7).
Other than the bones, the hip joint has capsules which are described as a heavy ligamentous structure encircling the whole joint. Inside the capsule is the synovial membrane whose main function is to nourish and lubricate (Foundation for the Advancement in Research in Medicine, Para. 2-4). The articular capsule is attached at the border of the acetabulum in the upper part, and in front of the labrum. Other than the capsules, the hip joint has ligaments.
The hip joint has three ligaments called iliofemoral, pubofemoral and ischiofemoral. Iliofemoral ligament usually forms a connection between the pelvis and the femur; clearly shown by Picture 3 and 4. Studies reveal that it connects the two just in front of joints. It is said to be strong and closely connected with the capsule. Its connection with the capsule makes it to have the role of strengthening to it. Other than being connected above, the iliofemoral ligament is also attached above. The attachment is to the lower section of the frontal lower iliac spine. In the lower part the ligament divides into two; the first division is attached to the intertrochanteric line. The second division, on the other hand, is attached to the upper part of intertrochanteric line (Foundation for the Advancement in Research in Medicine, Para. 2-4).
The two bands are separated, not all the times, by a part of the capsule. When there is no separation between the bands, the two move to form a triangular band which is usually fixed to the intertrochanteric line. The separated ligament is usually called the Y-shaped ligament of bigelow. The main role of this ligament in the hip joint is to prevent over-exhaustion during standing (Foundation for the Advancement in Research in Medicine, Para. 2-4).
The second ligament, pubofemoral, is said to be triangular in shape. Its base is usually fastened to the larger ramus of the pubis. The top part, on the other hand, is fastened to the lower side of the intertrochanteric line. According to scientists, pubofemoral plays a vital role in the hip joint. Its main function is to restrict the extension and abduction. The ischiocapsular ligament, like the pubocaspsular ligament has triangular bands of robust fiber. These fibers originate from the ischium and behind the acetabulum. The fibers blend to the fibers located at the capsule (Foundation for the Advancement in Research in Medicine, Para. 2-4).
The fourth ligament located in the hip joint is called ligamentaum Teres Femoris. It is triangular in shape. This ligament is said to be flattened and implanted into the fovea captis femoris. The base has two bands. The attachments have a synovial membrane with its strength varying. In some instances the synovial fold exists, while in other times, it does not exist. In order to make the ligament tense, the thigh must be semi flexed while the legs are folded. On the other hand, the ligament is relaxed when the legs are rotated inward. Other than the four ligaments, there is the transverse acetabula ligament. In real sense this ligament is part of the glenoidal labrum. However, it is different from it, in that it has cartilage cell in the fibers (Hip Anatomy, 237-238).
The hip joint has membranes, for example, the synovial membrane. This membrane is extensive in that it extends from the femur to the ligamental teres; the membrane originates from the head of the femur, the neck to the glenoidal labrum (Hip Anatomy, 237-238).
Muscles Found in the Hip Joint
Muscles in the hip joint are the one responsible for generating movements. There are five types of muscles located in the hip joint. The first muscle is called the gluteals. These muscles are the ones found in the buttocks. They are attached to the back side of the pelvis. The names of the muscles are gluteas maximus, minimus and medius. The Maximus is rhomboidal in shape. It comes from the posterior gluteal in. The muscles extend to the tuberosity of the femur. The main function of this muscle is to extend the hip. Moreover, it can rotate the hip. When the person is standing and the limbs are not moving, this muscle is responsible in extending the pelvis. This muscle is usually served by the inferior gluteal nerve. The medius and minimus make up one muscle which has only been divided into two. Kit is said to be from the iliac crest. The main functions of these two muscles are to rotate and abduct the thigh. It is served by the superior gluteal muscle (Hip Anatomy, 242-243). The second type of muscles is the quadriceps. As the name suggest, the muscles are four namely; “vastus lateralis, medialis, murintermedius and rectus femoris” (Hip Anatomy, 242-243). These muscles are found in the front of the femur and attach to the highest point of the ilium.
The third types are the iliopsoas which is the main hip flexor muscle. This muscle has three parts which attach to the “lower parts of pelvis and spine. They then cross joint and insert into the lesser trochanter of the femur (Foundation for the Advancement in Research in Medicine para. 17).”
The fourth types of muscles are the hamstrings muscles. These muscles comprises of the semitendinous and semimembrenous muscles. The source of these muscles is the Ischial tuberosity. These muscles have several functions; they flex the knee, rotate and abduct the leg. Other than hamstrings, there are the groin muscles which usually attach to the pubis. From the pubis they run down to the inside part of the thigh (Foundation for the Advancement in Research in Medicine paras. 17-19).
Range of Motion of the Hip
The movements related to the hip joint are wide. Examples of the movements are adduction and abduction. The bones are also responsible in establishing other forms of movement, for example, rotation which is brought about by the position of the neck of the femur and its position to the bones. When the thigh is moved, the head of the femur rotates. The movement of the neck usually affects the movement of adduction and abduction. Other than causing the rotation of the femur, the movement of the thigh causes an upward inclination. Just like the shoulder joint, the hip joint is known for its restriction of movement. When movements are carried out, the iliofemoral ligament is responsible for restricting a stretch that will cause the injuring of the hip joint. Its main function is to maintain a gait position without causing fatigue of the muscles. In addition, to the iliofemoral ligament, protection of the bones is also provided by the ligamentum teres (Hip Anatomy, 240-241).
The first range is called the flexion which is mainly restricted to the hamstring muscle. The second is extension which is restricted to ligamentous thickening of the capsule. The other motions, for example, abduction, adduction and rotation are restricted to the adductor, tensor and fibrous capsular fibers and muscles respectively. The range of abduction is said to be 450 and adduction, 300 (Hip Anatomy, 240-242).
Force Output/Capacity of the Joint
The hip joint is known to create and withstand certain types of forces. Examples of the forces that the hip joint creates are joint reaction force, coupled forces and instant center of rotation. On the other hand, the joint is able to withstand forces like the joint reaction forces and downward forces (Kreuz et al., 899-902)
Disease that affect the Hip Joint
A common disease that affects the hip joint is called the Perthes’. This disease is usually characterized by the softening and breaking down of the femur. It usually affects children. Pertehes’ was first discovered by three scientists in 1910. It was first given the name Calve’-Legg-Perthes, according to the scientist who discovered it. As mentioned above, the Perthes’ disease affects the femur. The softening and the weakening of the femur occur as a result of the blood vessels supplying the head with nutrients failing to do so. When the femur does not receive the needed nutrients, the bone cells die making it weak and soft. When the bones soften they become vulnerable to cracks and pressure thus fractures on the hip joint (Wright, paras. 1-4).
The symptoms of this disease are limping, pain on the hip joint, reduction in the range of movement, and after sometime the leg becomes thin and appear shorter than the other leg. In some case, the blood vessels regrow and continue to supply the blood to the bones. The supply causes the regrowth of the cells forming new bones. However, with Perthes’ disease, it takes a longer time to form the bones. This is because the formation of an accurately round femur that fits the acetabulum is difficult to form (Wright, paras. 1-4).
Injury that affects the Hip Joint
There are a number of factors that can lead to the injury of a hip joint. The hips are mostly said to be very stable and therefore they do not get injured easily. However, activities such as running, sporting, and overuse may lead to the cause of hip injuries. The most occurring hip injury is dislocation that happens as a result of the ball at the top of the femur slipping out of the socket. This leads to the difficulty in moving the leg and severe pain. For such a dislocation of the hip joint to take place, there has to be a strong force involved such as a severe fall or an automobile accident. Additionally, a dislocation might occur as a result of a person being born with a hip displasia or a shallow hip socket since these two conditions make a person be susceptible to a dislocation more easily. The ligaments that are at the hip joint are often damaged with the occurrence of a dislocation (Hip Injury: Common and some not-so-common injuries of the hip joint Paras. 1-2).
The Sections of the Anatomy Damaged and How the Forces Cause the Injury
Since the hip is a ball-and-socket joint, it has a very high stability that allows it to move freely. For a dislocation to take place there has to be a very strong force that will make the femur to slip or pop out of the pelvis. When the thighbone (femur) is forced out of its socket in a backward direction, it is termed as a posterior dislocation. The anterior dislocation occurs when the thighbone is forced out of its socket in a forward direction. The dislocation of the hip joint is usually very painful. Also, the dislocation may cause damage to the nerves leading to a situation where a patient does not have feelings of the ankle or the foot (Hip Injury: Common and some not-so-common injuries of the hip joint Para. 2).
In addition, there are other injuries that occur as a result of a dislocation of the hip joint. These injuries cause damage to other parts of the body such the back injuries. Since for a dislocation to take place, there must be a great amount of force involved, there are high chances of the occurrence of fractures in legs or pelvis, head injuries or back injuries. This may lead to other complications such as impairment of some parts of the body as a result of head injuries or the back injuries. An example of these complications is the inability to be able to walk (American Academy of Orthopaedic Surgeons Para. 2).
The Common Fracture Site on this Joint
The common fracture site on the hip joint is the femur. There two types of femoral neck fractures that occur during a hip injury namely; non-displaced fractures and displaced fractures. The non-displaced fractures of the femoral neck are found when the x-rays indicate that the near-normal alignment. The displaced fractures occur when the initial x-rays show the femur to be severely misaligned. It is seen that this is the common site of the fracture since the dislocation occurs when the femur pops out of the pelvis (American Academy of Orthopaedic Surgeons Para. 3).
One Treatment Option that can be used to treat this Injury
Femoral neck fractures can be treated depending on the type of fracture that has occurred. Non-displaced fractures can be fixed internally by placing multiple stabilizing crews from lateral part of the proximal femur and affixed into the femoral head bone. However, the displaced fractures of the femoral neck can be treated through arthroplasty or hemiarthroplasty depending on a number of multiple factors. These factors include the patient’s health status, cognitive status, age, surgeon preference and functional abilities. Surgeons ensure that they select the best implant for a patient suffering from a hip joint injury in order to achieve a satisfactory fracture reduction. Therefore, the most preferred treatment method for femoral neck fractures is arthroplasty since it provides the best alternative treatment (Butler, Forte, Kane RL, et al. Para. 4).
It is noted that there are two types of arthroplasty known as hemiarthroplasty and total hip arthroplasty. Hemiarthroplasty is the replacement of the femoral head section of the femur with a complete artificial implant. The acetabulum of the patient is not replaced and that is why it is termed as hemi-arthroplasty. The total replacement of the hip joint is called total hip arthroplasty. This is majorly done to elderly patients who may develop difficulty in regenerating the complete healing. It is therefore indicated that the total hip aarthroplasty is applied to patients who are active at the time they got the hip joint injury or those who are displaying severe degenerative changes (Hip Injury: Common and some not-so-common injuries of the hip joint Para. 5).
Total hip arthroplasty uses the anchored metallic rod that outspreads to the femur and to the mid-thigh region. This reduces the erosion that occurs due to movement within the articulate region. The metallic femoral head moves within the artificial socket to permit near normal hip movements after recovery.
The Biomechanical Aspects of Applying a Splint to a Hip joint
The biomechanical aspect of applying a splint to a hip joint is by the use of the artificial metallic replacements for the femur and the socket. The femur and the socket are replaced depending on the extent of the injury that has occurred in a person. It is therefore important to note the splint application to the hip joint is done depending on the extent of the fracture made (Kreuz et al., 899-902).
Abduction splints for treating dislocations comprises of restricting the limbs at the hip flexion. The forces involved are engrossed in dissimilar types of shoulder fastenings and therefore averted to the shoulder and the backbone. These forces are linked with a person’s body mass. Studies reveal that the maximal forces applied at the shoulder are much higher in small children than in adults; this is usually seen when a Tubinger Splint is used (Kreuz et al., 899-902).
In summary, hip joint is a very important joint in the body. The function of the hip joint is very essential in locomotion. Its ability to facilitate movement and support the body is supported by the various structures like the muscles, ligaments and membranes. These organs play a vital role in assisting the hip joint carry out its duties. Like any other body part, the hip joint is susceptible to injuries and diseases, though it is rear. This injuries or disorders may be caused by the lack of certain nutrients in the diet or vigorous exercises. An injury to it such as a dislocation may make a person develop complications that may lead inability to move permanently. There are a number of fractures that result as a consequence of dislocation. Therefore, it is very important to look after the hip joint. Care and attention must always be taken in case of an injury or disorder.
“Foundation for the Advancement in Research in Medicine.” About the Hip Joint, 2013. Accessed 3 May, 2013
“Hip Injury: Common and some not-so-common injuries of the hip joint.” Accessed on 4 April 2013 < http://www.arthritistoday.org/where-it-hurts/hip-pain/causes/hip-injury-fracture.php>
American Academy of Orthopedic Surgeons. Hip Dislocation. Accessed on 4 April 2013
Hip Anatomy. Functional Anatomy of the Hip Joint, n.d. Accessed 3 May, 2013
Kreuz, P.C. et al. "Biomechanical Evaluation of Different Abduction Splints For the Treatment of Congenital Hip Dysplasia." Clinical Biomechemicals (Bristol, Avon), 27.9 (2012), 899-902. Wright, Michelle. Perthes' Disease, 2012. Accessed 3 May, 2013
Picture I: Picture of the Hip Joint
Picture 3 and 4: Front and back View of the hip joint