the NeXT level functional anatomy of the hip BCRPA Approved Workshop (3 CEC s) ADVANCED SERIES

Transcription

1 the NeXT level TM functional anatomy of the hip BCRPA Approved Workshop (3 CEC s) ADVANCED SERIES Written by: Gillian Tews, Physiotherapist Aaron Tews, BSc Kin Copyright: February 2012 (version 2.01)

2 INTRODUCTION The lower limb is our vehicle for walking, running and jumping. It has developed strength and stability in order to support our body weight and maintain our balance. The hip and pelvic joints in particular are responsible for transmitting forces from the lower limb and distributing them to the trunk/ spine. Because of this important role, the hip joint has sacrificed some mobility in favour of stability. Unlike its counterpart in the upper limb, the shoulder, the hip joint is a more complete and congruent ball and socket joint, with more bony support than the shoulder joint has. Consequently, it does not have the same amount of mobility as the shoulder does. Whereas the upper limb has been designed for excellent freedom of movement and dexterity, it functions mostly as an open kinetic chain. This means that the distal end (hand) moves freely through space. Because the main function of the hip joint is one of weight bearing and ambulation, it usually functions in a closed kinetic chain, This means that it usually works with the foot (end of the chain) in contact with the ground/ support surface, while the proximal end (joints above the foot) moves through space. When this is the case, it becomes necessary to consider the role of the hip joint in relation to the knee, ankle and foot. In addition, the hip joint will affect the pelvis and spine as the kinetic chain continues via these segments as well. As we explore the hip and its functional role, let us review basic anatomy, discuss the effects of hip dysfunction, and study 2 significant and relevant activities that we experience commonly in the fitness field: The running gait and the standing squat exercise. 2

3 anatomical review anatomy of the hip can be organized into 5 basic systems: 1 Skeletal System 2 Capsular / Ligamentous System 3 Muscular System 4 Neurological System 5 Vascular System

4 ANATOMICAL REVIEW 1. Skeletal System The hip joint is very structurally strong, with the hemispherical head of the femur fitting snugly in the acetabulum of the innominate bone. It is classed as a multiaxial synovial ball-and-socket joint. It has 3 degrees of freedom of movement, i.e., flexion, extension, abduction/ adduction and internal/external rotation. The bones that make up the hip joint are: proximal femur, and the union of 3 pelvic bones (ilium, ischium and pubis) that form the acetabulum. Because functionally, the hip works intimately with the pelvic joints, it should not be considered in isolation. Important features of the proximal femur are: The head of the femur: smooth, and forms approximately 2/3 of a sphere. It is directed medially, superiorly and anteriorly. It makes up the ball of the ball and socket joint., and it fits deeply into the acetabulum of the pelvis. Clinical Point Osteoporosis means porous bone. As bones lose density, they become weaker and more prone to fracture. Careful guidance in weight bearing and resisted exercise can help strengthen osteopenic / porotic bones because it helps stimulate osteoblastic (bone building) activity. Did You Know? The neck is frequently fractured in the elderly. The neck has many pits where blood vessels enter the bone. These vessels are vulnerable to injury when the neck fractures The neck of the femur: connects the head to the body of the femur. It runs inferolaterally at an angle of about 125 degrees. The greater trochanter: a large 4

5 ANATOMICAL REVIEW projection on the lateral aspect at the junction of the femoral neck and body. It provides attachment for the gluteal muscles, piriformis, tensor fascia lata, obturator internus, superior gemellus. The greater trochanter is a bony prominence that is palpable on the lateral side of the thigh. Did You Know? A synovial joint must have a joint cavity, articular cartilage, a synovial membrane and a fibrous capsule. Synovial fluid minimizes joint friction Articular cartilage has no nerves or blood vessels and gets its nourishment from synovial fluid The lesser trochanter: projects from the posteromedial aspect of the femur between the neck and body. It provides attachment for the psoas major and iliacus muscles. The body of the femur: slightly bowed anteriorly and narrowest at its midpoint. In the posterior surface below the neck is a rough area called the linea aspera. On the medial surface, running from the lesser trochanter to the medial lip of the linea aspera is the pectineal line. This is the attachment for the pectineus muscle. 5

6 ANATOMICAL REVIEW 2. Capsular/Ligamentous System The capsule is strong and dense. It is attaches proximally around the edge of the acetabulum. Distally, it is attached to the neck of the femur. It forms a cylindrical sleeve around the hip joint. Most of the fibres are spiral in their course (zona orbicularis). This zone helps to keep the femoral head in the acetabulum. Some other fibres run longitudinally (retinacula) and contain blood vessels which supply the head and neck of the femur. The intrinsic ligaments are capsular thickenings that reinforce the capsule. These include: iliofemoral pubofemoral, ischiofemoral ligaments. There is one intracapular ligament called the ligamentum teres. Iliofemoral Ligament: This is a very strong Y-shaped ligament that covers the anterior aspect of the hip joint. It is attached from the anterior inferior iliac spine and acetabular rim, to the 6

7 ANATOMICAL REVIEW intertrochanteric line of the femur. It becomes taut when the hip is extended. It has an important role in maintaining upright posture and preventing over extension of the hip. Pubofemoral Ligament: This ligament comes from the pubic part of the acetabular rim and iliopubic eminence and blend with the medial part of the iliofemoral ligament. This ligament reinforces the inferior and anterior capsule. It becomes tight during extension and abduction. This is a relatively weak ligament, but is does check over abduction of the hip. Ischiofemoral Ligament: This ligament strengthens the posterior aspect of the capsule. It attaches from the ischial part of the acetabular rim and goes to the neck of the femur, in a spiral course. Its structure tends to screw Did You Know? When a violent injury causes a fracture of the femur, it can take up to 20 weeks for fragments to unite firmly. Fractures of the neck occur more commonly in post menopausal women due to osteoporosis. the femoral head medially into the acetabulum during extension Ligamentum Teres: This ligament seems to be of little importance to the stability of the hip joint, but it usually contains a small artery to the head of the femur 7

8 ANATOMICAL REVIEW 3. Muscular System The anterior group of hip muscles include: tensor fascia lata, sartorius, quadriceps femoris, iliacus and psoas major. The main job of these muscles is to flex the hip, but some may also abduct the hip or flex the knee. Most anterior muscles are supplied by the femoral n., except the tensor fascia late, which is supplied by the superior gluteal n, and the psoas major, which is supplied by the ventral rami of L1,2. Did You Know? Sartorius is the longest muscle in the body. Did You Know? If the quadriceps muscle is paralyzed, the knee cannot be actively extended, but the patient can still stand on the leg because the body weight tends to hyperextend the knee joint. Muscle Origin Insertion Neural inervation Action Tensor fascia lata Sartorius Quadriceps Femoris Iliacus Psoas Major anterior part of the external lip of the iliac crest and lateral surface of the anterior superior iliac spine Iliotibial tract at the greater trochanter anterior superior iliac spine superior part of the medial surface of the tibia, anterior to the insertions of gracilis and semitendinosis (rectus femoris) anterior inferior iliac spine and groove superior to the acetabulum. (vastus lateralis, medialis and intermedius)- body of the femur Iliac crest, fossa, ala of sacrum and iliolumbar and ventral sacroiliac ligaments Transverse processes, and sides of vertebral bodies and intervertebral discs of T12 to L5. all 4 heads unite to insert into the base of patella and the common tendon continues inferiorly to the tibial tuberosity as the patellar tendon. The aponeuroses of the vasti muscles form the medial and lateral retinacula of the patella and insert into the femoral condyles. Most fibres insert into the lateral side of the psoas major tendon, and inferior to the lesser trochanter superior gluteal nerve (L4,5) Femoral nerve (L2.3) femoral n. (L2,3, 4) femoral n. (L2,3) I-lesser trochanter ventral rami of L1,2 and 3 abducts and flexes thigh, and helps to keep the knee extended in erect posture by making the IT Band taut. It also steadies the trunk on the thigh, and helps to counteract the posterior pull of gluteus maximus on the IT Band flexes the thigh and leg, and aids abduction and lateral rotation, e.g., when you sit with crossed legs Extends the knee joint. Only the rectus femoris portion flexes the hip joint. All parts of the quadriceps are used during climbing, running, jumping and rising from a chair flexes the hip (with psoas) Chief hip flexor. It works directly with the iliacus, and the two muscles are referred to as iliopsoas 8

9 ANATOMICAL REVIEW The medial thigh muscles include: the adductor magnus, longus, brevis, pectineus and gracilis. The main action of these muscles is to adduct the hip. All adductors of the hip are supplied by the obturator n, except for pectineus, which is supplied by the femoral nerve. Also, the hamstring portion of adductor magnus is supplied by the sciatic n. Did You Know? Because the Gracilis muscle is the weakest of the adductors, it has little impact on their function. So, surgeons will often use Gracilis for transplanting into other damaged muscles. Muscle Origin Insertion Neural inervation Action Adductor Magnus Inferior ramus of the pubis, ischial ramus and ischial tuberosity gluteal tuberosity, linea aspera, medial supracondylar line, and adductor tubercle Posterior division of the obturator nerve and tibial division of the sciatic nerve the adductor portion adducts, and the hamstring part extends the hip Adductor Longus anterior surface of the body of the pubis Middle 1/3 of the linea aspera Obturator nerve (L2,3,4) adducts and flexes the hip. It also can fixate the hip during knee flexion and it can externally rotate the hip when the hip is flexed. Adductor Brevis Body and inferior pubic ramus Pectineal line and proximal part of linea aspera Obturator nerve (L2,3,4) adducts the hip and assists flexion Pectineus pectineal line of pubis Pectineal line of femur Femoral nerve (L2,3) Adducts and flexes the hip Gracilis Body and inferior pubic ramus superior part of the medial tibia, just posterior to sartorius Anterior division of the obturator nerve adducts the hip and flexes the knee Obturator Externus margins of the obturator foramen and membrane trochanteric fossa on the posterior aspect of the femur Obturator nerve (L3,4) Externally rotates the hip 9

10 ANATOMICAL REVIEW The muscles of the gluteal region include: Gluteus maximus, medius and minimus, Piriformis, Obturator internus and Quadratus femoris. These muscles generally extend the hip, and externally rotate it. The nerve supply for the gluteal muscles is varied, but is derived from L5 to S2 nerve roots. Functionally, gluteus maximus becomes very important in the running gait, especially with higher speeds and/ or inclined surfaces, because it controls the forward pitching of the trunk. Clinical Point Pulled hamstrings (strain/ tear) are common sports injuries in running or kicking. Sometimes the force of the injury can avulse the tendon from the ischial tuberosity Muscle Origin Insertion Neural inervation Action Gluteus maximus Gluteus medius Gluteus minimus Piriformis Obturator internus Quadratus femoris External surface of the ilium, and iliac crest, dorsal surfaces of the sacrum and coccyx, and the sacrotuberous ligament external surface of the ilium between the anterior and posterior gluteal lines External surface of the ilium between the anterior and inferior gluteal lines anterior surface of the sacrum and sacrotuberous ligament Pelvic surface of the obturator membrane Lateral border of the ischial tuberosity The iliotibial band, and gluteal tuberosity of the femur Lateral surface of the greater trochanter anterior surface of the greater trochanter superior border and medial surface of the greater trochanter medial surface of the greater trochanter Quadrate tubercle of femur Inferior gluteal nerve (L5, S1,2) superior gluteal nerve (L5, S1) superior gluteal nerve (L5,S1) ventral rami of S1,2 nerve to obturator internus (L5, S1) nerve to Quadratus femoris (L5,S1) Extends the hip and stabilizes it. This is the main hip extensor. It can also extend the trunk/ pelvis e.g. standing up from sitting. It also externally rotates the hip abducts and medially rotates the hip. It also has an important role in steadying the pelvis during walking/ running abducts and medially rotates the hip and steadies the pelvis along with gluteus medius laterally rotates the hip when it is extended, abducts the hip when it is flexed. It holds the head of the femur into the acetabulum, so it is a hip joint stabilizer NB---the piriformis muscle is used as a landmark of the gluteal region. It determines the names of nerves and blood vessels laterally rotates the hip when it is extended, abducts the hip when it is flexed (has the same action as piriformis). It also acts as a hip joint stabilizer Laterally rotates thigh 10

11 ANATOMICAL REVIEW There are 3 bursae (fluid filled sacs that reduce friction where muscles overlie tendons or bones) associated with the gluteus maximus: Trochanteric bursa protects it from the lateral side of the greater trochanter Gluteofemoral bursa protects it from the superior part of the origin of vastus lateralis Ischial bursa protects it from the ischial tuberosity Clinical Points The ischial bursa can become inflamed as a result of excessive friction on the sitting bones e.g. rowing. Trochanteric bursitis can occur due to a tight iliotibial band fractioning over it. Did You Know? The function of gluteus maximus is thought to be specialized for running. Well recognized as a hip extensor, it has been found that during level walking, the activity of this muscle is fairly quiet. It begins to become more active as speed and incline increases, because the degree of trunk flexion is greater. During running, gluteus maximus is very active, particularly at higher speeds and inclines. [glut max study] 11

12 ANATOMICAL REVIEW The posterior thigh muscles include: the hamstrings -- semimembranosus, semitendinosus, and biceps femoris. The hamstrings share a common origin from the ischial tuberosity, but the biceps also has a separate origin from the posterior aspect of the femur. These muscles are 2- joint muscles since they cross the hip and the knee. Muscle Origin Insertion Neural inervation Action Semimembranosus Ischial tuberosity posterior part of the medial condyle of the tibia Semitendinosus Ischial tuberosity posterior surface of the medial condyle of the tibia, posterior to gracilis and sartorius Biceps Femoris ischial tuberosity (long head) and lateral lip of the linea aspera and lateral supracondylar line Fibular head Tibial division of the sciatic n. (L5,S1, S2) Tibial division of the sciatic n. (L5, S1, S2) tibial division of sciatic n. (long head) and common division of the sciatic n. (short head) extends the hip and flexes knee. When it acts with semitendinosus, it can medially rotate the knee extends hip, flexes knee and medially rotates knee extends hip (long head), flexes knee and laterally rotates knee 12

13 ANATOMICAL REVIEW 4. Nervous System The segmental nervous supply to the hip joint comes from L2 (Lumbar 2) to S1 (Sacral 1) The peripheral nerves supply comes from the anterior branch of the obturator nerve, which contributes to the anterior, medial and inferior joint capsule. The posterior branch of the obturator nerve, supplies the posterior and inferior capsule as well as the intraarticular structures. There is also additional nerve supply from the femoral, superior gluteal and sciatic nerves. The dermatomes that the skin over the hip joint represents are L1 and L2. The following diagram outlines the sensory distribution of peripheral nerves around the hip and thigh. Did You Know? A dermatome is the area of skin that is supplied by a single nerve root. One should be aware of the general area of the dermatomes and understand that there is a great deal of overlap. Sensory changes in a dermatome may indicate dysfunction in the spinal segment it represents. Clinical Point Impingement of the lateral cutaneous nerve of the thigh as it comes out of the pelvis by the anterior superior iliac spine can occur, resulting in tingling, numbness or pain in the anterolateral aspect of the thigh. This is called meralgia paraesthetica. This happens most frequently in pregnancy, but can also occur as a result of a direct blow to the thigh in sport. NB -Always refer a client to a therapist if he/she complains of sensory changes. Spinal or pelvic causes need to be ruled out. 13

14 ANATOMICAL REVIEW 5. Vascular System The hip joint and labrum are supplied by the acetabular branches of the obturator and medial femoral circumflex arteries by way of the ligamentum teres. The joint capsule is supplied by the medial and lateral circumflex artery, the ascending branches of the medial and lateral circumflex arteries. Clinical Point A condition called avascular necrosis (death of the bone due to lack of blood supply) can occur at the femoral head if the blood supply is lost due to trauma e.g. fracture. 14

15 biomechanics biomechanics of the hips: 1 Biomechanics 2 Role of the hip in Gait 3 Biomechanics of the Running Cycle 4 Posture & Form Considerations for Safe Running 5 Posture & Form in Exercise 6 Common Postural Dysfunction 7 Injuries from Running

16 BIOMECHANICS OF THE HIP JOINT 1. Biomechanics of the Hip Joint The hip joint is a multi-axial ball-and-socket joint with 3 degrees of freedom. Flexion = 120 degrees Extension = degrees Abduction = 45 degrees Adduction = degrees Medial (Internal) Rotation = degrees Lateral (External) Rotation = 60 degrees A B A B A B PRONE Medial Rotation (A) Lateral Rotation (B) SITTING Lateral Rotation (A) Medial Rotation (B) SUPINE Hip Adduction (A) Hip Abduction (B) 16

17 Role of Hip in Gait 2. Role of the Hip in Gait Running is a part of many sports, recreational activities and exercise programs. Understanding gait is important when training individuals. Many novice exercisers choose running as a way to lose weight, or to get in shape quickly. Others who are returning to fitness after many years try running because it is what they used to do when they were young. By appreciating the mechanics of the hip during locomotion, the forces this joint needs to withstand and the muscular control required to perform the task, we can provide the most effective and safe training programs for our clients. It is also important to consider the relationship that the hip has with the pelvis, knee and ankle in gait in order to appreciate its role in ambulation. Generally, the running cycle is a pattern of hopping from one leg to the other as one falls forward. The pattern is made up of a stance phase, when one foot is in contact with the ground, followed by a swing phase, when the foot is off the ground. Then there is a period of time when both feet are off the ground called float phase. At a speed of 10k/hour, each running cycle will take approximately 0.7 seconds. Of this, the stance phase of each leg only lasts about 0.2 seconds! Running is interesting because the lower limb acts in both a closed and open kinetic chain during stance and swing/float phase respectively. 17

18 Role of Hip in Gait The lower limb is exposed to the most stress during the stance phase, when it is weight bearing, because the muscles, ligaments and joints are accepting ground reaction forces, and controlling forward momentum of the trunk.. Furthermore these forces need to be distributed over a very short period of time. Understandably, it is during stance that most running injuries occur. During swing phase the muscles about the hip have a dual function of moving the leg forward quickly (acceleration) and then slowing it down again (deceleration) to prepare for the next step. The gait pattern of running differs from that of walking in some key ways. Amount of time spent in stance phase is less (1/2 to 1/3) The forces transmitted through the lower limb are increased significantly There are 2 float phases when both feet are off the ground. In walking, there are 2 points of double contact, when both feet are in contact with the floor. Stance phase consists of 3 parts: Heel Strike-- occurs when the heel makes contact with the ground Midstance -- weight is evenly distributed over the foot, and energy is stored in the tendons and connective tissue of the lower limb. Toe-Off -- takes place when the foot leaves the ground, and the body is propelled forward. The time between heel strike and midstance is called braking because during this time, there is a controlled landing and impact forces of the ground are being absorbed by the flexion of the knee, ankle and foot, and kinetic energy is stored in the tendons and myofascial as elastic energy. The time between midstance and toe-off is called propulsion because at this time, the hip and knee extend and the ankle plantarflexes to drive the body forward and up for the next step. The stored energy from the braking phase is used to help propel the body as well, to increase efficiency. NB---At least half of the stored recoil energy comes from the Achilles and foot tendons! 18

19 BIOMECHANICS OF RUNNING CYCLE 3. Biomechanics of the Running Cycle Just prior to heel strike, the hip has already started extending, pulling the foot back towards the hips. If the hamstrings/ gluteal complex is not sufficiently working to pull back on the limb, the braking forces at contact will be excessive, which could lead to injury. At heel strike, the hip can be flexed 30 to 49 degrees, and is medially rotated. The greater the amount of trunk flexion, the greater the hip flexion required. The knee is flexed 30 to 40 degrees, and the ankle is dorsiflexed about 10 degrees. The trunk and the pelvis will be tilted anteriorly degrees. During the absorption phase (heel-strike to midstance), trunk flexion increases by 2-5 degrees. This slight forward flexing of the trunk during the braking phase helps to maintain the body s forward momentum. Gluteal, hamstrings, abdominals and erector spinae muscles are all active to control the trunk and pelvis during the absorption phase. By midstance, the hip flexes, the knee flexion increases to degrees, and the ankle dorsiflexes to about 20 degrees. This helps with the absorption of forces as braking occurs. At distance running speeds, the lower limb withstands a vertical force of 2 to 3 times body weight, and a forward shear of 50% body weight and a medial shear of 10% body weight. All these forces need to be dissipated over a few milliseconds because the whole stance phase only lasts approximately 0.2 seconds! 19

20 BIOMECHANICS OF RUNNING CYCLE Most of the forces at heel strike are due to slowing down the lower limb at initial contact. The active forces through the limb are a result of the movement of the center of mass of the whole body during the rest of stance. Overall, the forces acting on the body can be up to 10 times the body weight [Reid pp1132]. During mid-stance, the hip must begin to externally rotate, and it extends to 20 degrees flexion. A great amount of force is placed on the hip at this point. Most of the force accepted by the lower limb occurs just after heel-strike, as the weight is taken at the centre of the heel about 15ms after heel-strike. The eccentric strength of the quadriceps and triceps surae (calf) is very important here to control knee flexion and ankle dorsiflexion. If these muscles are not adequately working, these joints will tend to collapse. During propulsion the ankle, knee and hip combine in a triple extension movement to provide the drive upwards and forwards. The hip extends to 10 degrees, the knee begins to extend to degrees flexion, and the ankle plantarflexes to 25 degrees. The calf, quadriceps, hamstring and gluteal activity during the propulsion phase is less than during the absorption phase, because the propulsion energy comes mainly from the recoil of elastic energy stored during the first half of stance. The role of the muscles therefore is to control the joint positions, creating stiffness in the leg system that allows the tendons to lengthen and then recoil. The trunk re-extends to the initial position at heel-strike. The pelvis will tilt further anteriorly by 5-7 degrees. This slight shift in the anterior tilt of the pelvis helps to direct the propulsion forces of the leg horizontally. If the pelvis were in neutral then the triple extension of ankle, knee and hip would be directed more vertically. So, a slight forward lean and anterior pelvic tilt is considered to be efficient for running. At toe-off, the hip begins to rotate medially During the swing phase, the knee and hip flex to maximum flexion angles of 130 degrees and 60 degrees respectively and then re-extend prior to heel-strike. At the hip joint, psoas major and rectus femoris act phasically to flex the hip. Just prior to heelstrike, the gluteus maximus/ hamstrings begin to slow down the limb by working eccentrically, and then begin to extend the hip again prior to heel strike. The ankle dorsiflexes throughout swing to 10 degrees at heel strike.. The gluteus maximus and hamstrings increase their activity by 30 to 50% compared to their levels during walking, so they can work to decelerate the leg after swing phase. Hip abductors (gluteus medius and tensor fascia lata) work throughout the entire cycle to help stabilize the pelvis. 20

21 POSTURE & FORM 4. Posture & Form Considerations for Safe Running Running posture and form are important for well-being and efficient training. Safe running requires coordination of appropriate movement at eh pelvis, hip, knee and ankle. It also needs adequate strength, control and timing of the lower limb muscles. If there is excessive braking forces during stance phase because of a poor running style, injury will likely occur. It is essential that the ankle and knee can quickly control the braking forces and create a stable leg system to allow the tendons to maximize their recoil power. If a runner bounces upward versus forward, it will increase the landing forces, putting greater stress on the joints and requiring more muscle force to control. If the runner leans her trunk forward too much, it may mean that the posterior chain muscles i.e., erector spinae / gluteals / hamstrings are weak. This will increase the strain on the hamstrings and back during the running action. If the runner s trunk tends to be too upright, there will be a tendency to move up/down excessively during a stride which will increase landing forces. Runners need to learn to bounce along and not up, by taking quick, light steps. It is also important to bring the foot back prior to heel-strike using active hip extension as this reduces braking forces and time needed for the absorption phase. GOOD POOR Trainer s Tip When designing exercise program, consideration needs to be given to postural muscles with respect to appropriate stretching, strengthening and body awareness for clients. 21

22 POSTURE & FORM Good strength in the gluteals, hamstrings, quadriceps and calf muscles will help runners achieve this. The position of the pelvis is important as well. If the pelvis is tilted too much during absorption phase, it may mean that the gluteals and abdominals are not controlling the pelvis during landing, or that quadriceps may be working incorrectly, or there may be reduced hip flexibility. During the propulsion phase, if there is excessive anterior tilt, there may be tight hip flexors with insufficient hip extension. This will reduce the power of the hip and cause a compensation of lumbar extension, which could lead to back pain or injury. In general, a poor trunk position or lack of pelvic stability is likely to reduce the efficiency of the running action, creating extra load on the leg muscles or increasing stress through the lumbar spine and pelvis. Any of these negative factors can increase the likelihood of injury. The aim of the pelvis and trunk in the frontal plane during stance phase is to be stable and provide balance. The gluteus medius muscles (abductors) are of primary importance in providing lateral stability: Their eccentric action prior to and during the absorption phase prevents the hip from dropping down too far to the swing leg side. If there is inadequate gluteus medius action, there will be excessive or poorly controlled lateral tilting of the pelvis (Trendelenburg Gait). This will result in adverse forces through the lumbar and sacroiliac joints, and causes the knee of the stance leg to internally rotate, which leads to over- pronation of the ankle/ foot. Notice how just one unstable link in the kinetic chain can increase the risk of injury anywhere along the chain. Running predisposes athletes to development of tight hip flexors and hamstrings. Also, hip flexor power is often disproportionate to that of other muscle groups. Because of this, there can be a tendency for acute hamstring strains, especially in sprinters. Normal Gluteus medius (A) Weak Gluteus medius (B) 22

23 POSTURE & FORM IN EXERCISE 5. Posture and Form in Exercise Many clients look to personal trainers to help them get in shape, lose weight or to prepare for a particular sport. Many beginners and even some experienced exercisers may have less than ideal movement patterns and postures. Without consideration, this could interfere with the efficiency of the training you prescribe, or even result in injury despite the best intentions of the exercise. Ideal posture means: the alignment of bones, joints and muscles which minimizes strain and maximizes stability and energy efficiency in the body. We often associate good posture with the static plumb line model for sitting and standing. In fact, there are a myriad of ideal arrangements for our bodies for any position, movement or activity. Ideal dynamic posture is referred to as good form in sport. Basic static posture is a helpful starting point for identifying key areas of weakness, tightness and level of body awareness. Let s look at ideal standing, and a common postural dysfunction that you may encounter in the gym The plumb line runs from the external auditory meatus (ear), through the vertebral body of C7/T1, through S2, posterior to the hip joint, anterior to the knee and through the lateral malleolus (roughly). The normal curves of the spine in the anterior/ posterior plane are: lordosis in the cervical spine, kyphosis in the thoracic spine and lordosis in the lumbar spine. The pelvis is angled approximately 30 degrees. From the posterior view, the head is midline, spine straight, the scapulae aligned between T2 to T7, the waist angles equal, pelvis level and Achilles tendons vertical. Some causes of faulty posture include: Poor habit Spending long periods of time sitting Muscle imbalances, contractures (e.g., tight psoas, pectoralis minor) Pain, respiratory conditions (e.g., emphysema) General weakness/ de-conditioning Obesity Poor body / kinesthetic awareness Structural factors such as pelvis / spine / feet out of alignment. 23

24 POSTURE & FORM IN EXERCISE 6. Common Postural Dysfunction Excessive Lordosis or anterior curvature of the lumbar spine (sway back), with anterior tilting of the pelvis. This occurs as a result of: Lax or weak abdominal muscles Heavy abdomen (obesity or pregnancy) Hip flexion contracture (tight psoas) Spondylolisthesis Often associated with excessive lordosis are sagging shoulders, medially rotated hips, and a forward head posture. Such a posture places increased compression on the lumbar facet joints, which can lead to osteoarthitis. It also stresses the iliolumbar ligament, and increases the risk of anterior impingement of the hip joint (psoas tendon). Did You Know? Spondylolisthesis is an anterior slippage of one vertebra on the one below it. 24

25 INJURIES FROM RUNNING 7. Injuries from Running While most running injuries involve the knee, ankle and foot, problems do happen at the hip. Some common hip injuries include: Piriformis Syndrome Trochanteric Bursitis Iliotibial Band Syndrome Hamstring Strain/ Tear In addition, because of the closed kinetic chain relationship among the lower limb joints, it needs to be remembered that dysfunction in the hip e.g. muscular imbalances, can also manifest as pain in the other joints/ segments. Piriformis Syndrome This problem can appear as pain deep in the buttock. Because of its relationship to the sciatic nerve, it may cause sciatica (pain down the back of the leg). In 85% of people, both parts of the sciatic n. pass deep to piriformis, in 10% of people, the peroneal portion passes directly through it. In 2-3%, the peroneal portion loops superior then superficial to piriformis, and in only 1%, the entire nerve passes through the muscle belly. These relationships and variations mean that the tone and/or tightness of the piriformis and its myofascia can directly influence the sciatic n. Some exercises that can help Piriformis Syndrome or prevent it include: Piriformis Stretches Gluteus Medius Strengthening Clinical Point If a client complains of sciatic symptoms, always refer to a physiotherapist to assess because sciatica can also be due to other more serious problems e.g., herniated lumbar disc. 25

26 INJURIES FROM RUNNING Adductor Stretches Core Stability (especially Transversus Abdominus and Pelvic floor) Trochanteric Bursitis Pain on the lateral aspect of the hip over the greater trochanter usually signifies irritation of the overlying bursa. Inflammation can occur as a result of weak/ over strained hip abductors or overreliance on tensor fascia lata. It can also be caused by a tight Iliotibial band that rubs over it during repetitive hip flexion/ extension. Some helpful exercises are: Gluteus Medius Strengthening Tensor Fascia Lata Stretch Core Stability Iliotibial Band Syndrome This problem can occur when this dense band of soft tissue becomes tight, or if it gets traumatized by frictioning over the greater trochanter, proximally or the lateral tibial condyle, distally. This can happen if there is muscular imbalance in the hip abductors and tensor fascia lata is overworking. Weak abductors/ Trendelenburg gait can also lead to this problem. When training, focus needs to be on: Tensor Fascia Lata, Quadriceps and Hamstrings Stretches Gluteus Medius and Adductor Clinical Point Always refer to a physiotherapist if you suspect iliotibial band syndrome because it may require specialized treatment e.g., myofascial release, laser therapy, or ultrasound 26

27 INJURIES FROM RUNNING Strengthening Core Stability Adductor Strengthening Hamstring Strain/ Tear This often occurs as a sudden onset pain in the proximal insertion of the hamstrings (ischial tuberosity) or in the belly of the muscle. If severe, some of the muscular fibres may be torn, and bruising/ hematoma will result. To avoid such an injury, it is important for the client to be adequately warmed up (not just stretching!) prior to a run. Also the running form especially at/ prior to heel strike needs to be correct to minimize excessive braking forces required by the limb. Eccentric hamstring strength and control is important as many strains occur during swing phase as the runner is extending the leg through range. Training tips include: Hamstring and Psoas Stretching Eccentric as well as concentric hamstring strengthening as various speeds Abductor Strengthening Core Stability Abnormal Gait Patterns A painful limb will result in a shorter stance phase as the client tries to get off the hurt leg as quickly as possible. This is the typical limp we see. Clinical Point Hamstring tears require the help of a therapist. Extreme caution needs to be taken that calcification does not occur within the muscle (myositis ossificans) during healing time. This can occur if training is too vigorous in the early-mid stages of healing. 27

28 INJURIES FROM RUNNING Weakness of the hip abductors, especially the gluteus medius will result in excessive lateral leaning of the trunk over the weak leg. The function of the hip abductors during gait is to keep the pelvis level while the swing leg lifts and moves forward. This compensation is done in an attempt to keep the pelvis level, since the gluteus medius is unable to do it by strength alone. This pattern is called Trendelenburg gait. Hip abductor weakness can occur for several reasons including muscular strain, or L4, L5 palsy. If the gluteus maximus is weak, the person will compensate by leaning backwards over the affected leg during stance, in an attempt to maintain hip extension Trendelenburg Gait The Role of the Hip in the Squat The squat is a common exercise in both training regimes and in recreational exercise programs. It can be an excellent means for strengthening the erector spinae, gluteus maximus and quadriceps, but if done incorrectly, can also be a source for knee and back injury. There are several types/ styles of squats; lets examine the 28

29 INJURIES FROM RUNNING biomechanics and muscular function of the basic squat. During the execution of a basic squat, the knees and the hips travel in opposite directions away from the foot, or away from the center of gravity. The hips are required to flex until the thighs are parallel to the floor, The knees flex and the ankles dorsiflex. The trunk remains in a neutral posture, but angled forward, so that the weight remains over the feet. Achieving this position requires adequate flexibility in the gluteus maximus and adductor magnus for hip flexion, and in the gastrocs/ soleus complex for ankle dorsiflexion. Injuries in the Squat Adequate hip joint flexibility into flexion is important when performing a full squat. Once available hip flexion is used up, further descent is only possible if the pelvis rotates posteriorly and the lumbar spine flexes. This could place the lumbar spine, intervertebral discs and sacroiliac joints at risk, especially if the erector spinae muscles and pelvic stabilizers are not strong enough to support the load, and/ or if the ligamentous structures have not adapted to this degree of stress. The flexibility of the hip joint can also assessed during the squat. As the subject performs the full squat (without weight), the point at which the pelvis begins to rotate posteriorly, should be noted. The compression of abdomen against the upper thigh may be a limiting factor for some individuals. Trainer s Tip The safest technique for the basic squat is one where the knee is flexed only to 90 degrees and the heels stay on the ground. The trunk should remain in neutral; because of hip flexion, it will angle forward. Remember that while the squat is a very common exercise, it is also generally poorly executed. For this reason, extra care should be taken to assess for adequate range of motion in, the hip and ankle, as well as for core control and stability prior to instructing the squat. Preparatory exercises may need to be done to prepare a client for the squat. Gluteus maximus and gastrocnemius / soleus stretches Core stability exercises Postural exercises 29

30 CONCLUSION Conclusion Understanding the form and function of the hip can help you design training programs for clients that are safe, efficient and meaningful. Exercise and movement involve many systems in the body bones and joints, ligaments, muscles, nerves and blood supply. We have examined these systems in relation to how the hip works in gait and in the squat. In addition, we have seen how posture can affect the function of this joint. All these anatomical components need to be considered, as well as how these relate to rest of the body as a whole. Aaron Tews, BSc. Kin, CPT, RK, FMS, BCRPA Trainer of Trainers Aaron graduated from the University of Victoria with a BSc. Kinesiology in 1993 and started his company VIP (Vancouver Island Professional) Fitness. His certification, memberships and accomplishments include: Member of BCAK (British Columbia Association of Kinesiologists) since 1995; Member of BCRPA as a recognized Trainer of Trainers for the Fitness Theory course, the Strength Training Specialty Module and the Personal Trainer courses since the mid-90's; and Certified instructor for the CPAFLA (Canadian Physical Activity, Fitness & Lifestyle Appraisal) course. In 2010, he completed Gray Cook s Functional Movement Screen (FMS) Certification. Aaron has published a book on resistance training called "A Professional Guide to Resistance Training (2005)." He also had the first BCRPA-recognized correspondence course for the Strength Training Specialty Module in the province of British Columbia. Aaron also owns active rehabilitation & personal training studio in Vancouver (Kitsilano), BC called KINESIOLOGISTS dot CA (InFOCUS Wellness Inc. dba). Aaron owns this Physical Culture Studio and practices what he preaches! Come by and visit West 6th Avenue, Vancouver (Corner of 6th and Pine). Gillian Tews, BScPT Education: -McGill University 1994 BScPT Professional Qualifications: -Diploma of Advanced Manual and Manipulative Physiotherapy (Part B) -Certified Gunn-IMS Therapist (CGIMST) -Yoga Instructor (RYT 200) Professional Organizations: -Canadian Physiotherapy Association (CPA) -Fellow of the Canadian Academy of Manipulative Physical Therapists (FCAMPT) -Institute for the Study and Treatment of Pain (istop) -International Association of Yoga Therapists (IAYT) Gillian is currently the clinic manager and senior physiotherapist at the Surrey CBI. 30

31 REVIEW QUESTIONS Review Questions to Consider 1. These bones make up to acetabulum: A. Pubis B. Iscium C. Ilium D. All of the above Answer = 5. The anterior group of muscles is supplied mostly by which nerve? A. Sciatic B. Obturator C. Femoral D. Tibial Answer = 2. Which of these is a feature of a synovial joint? A. Joint capsule B. Friction C. Arthritis D. None of the above Answer = 6. Which of these is NOT a hip joint ligament? A. Iliofemoral B. Ischiopubic C. Pubofemoral D. Ischiofemoral Answer = 3. What are normal ranges of motion for each movement of the hip? A. Flexion degrees B. Extension degrees C. Abduction degrees D. Adduction degrees E. Internal Rot n degrees F. External Rot n degrees 4. During weight-bearing, the lower limb is working as an open kinetic chain. True False Answer = 7. During which phase of the running gait cycle is the hip most at risk for injury? A. Float B. Stance C. Swing D. All of the above Answer = 8. What causes a Trendelenburg gait pattern? A. Weakness in the gluteus medius B. Tight iliotibial band C. Weakness in the hamstrings D. Tight quadriceps Answer = 31

32 REVIEW QUESTIONS 9. Which of these is a common running injury that occurs at the hip joint? A. Iliotibial band syndrome B. Trochanteric Bursitis C. Piriformis Syndrome D. All of the above Answer = 13. What is excessive lumbar lordosis, with respect to posture? A. Flat back B. Sway back C. Scoliosis D. Extra vertebra is present Answer = 10. Adequate hip flexion RoM is very important for performing a safe basic squat. True False Answer = 11. One exercise you could prescribe a client before teaching a basic squat exercise is: A. Heel raises B. Gastrocs/soleus stretches C. Hamstring curls D. Crunches Answer = 12. Ideal posture means: A. Always keeping a straight back B. Minimizing strain and maximizing efficiency C. Plumb line D. None of the above 14. Excessive lordosis increases the risk of: A. Osteoarthritis B. Osteoporosis C. Obesity D. Senility Answer = 15. When is it necessary to refer a client to a physiotherapist or physician? A. Neurological signs/symptoms are present B. Recent trauma C. If unsure about safety D. All of the above Answer = Answer = 32

33 REFERENCES References: 1. Sports Injury Assessment and Rehabilitation by David C. Reid, BPT, MD 2. Clinically Oriented Anatomy, 2 nd Edition, by Keith Moore 3. Physical Examination of the Spine and Extremities by Stanley Hoppenfeld 4. Orthopedic Physical Assessment by David J. Magee 5. Maureen Mooney: Manual Therapy Part A Examination Preparatory Manual 6. Anatomy and Asana: The Hip Joint, by Susi Hately Aldous, BScKin, RYT Internet Sources: sportsinjury.com/archive/biomechanics-running.html exrx.net/kinesiology/squats.html 33