1. HIP
Dr. Michael P. Gillespie

2. OSTEOLOGY
Each innominate is the union of three bones: the ilium, pubis, and ischium.
The right and left innominates connect with each other anteriorly at the pubic symphysis and posteriorly at the sacrum.
An osteoligamentous ring known as the pelvis (Latin: basin or bowel) is formed.
Functions of the pelvis:
Attachment point for many muscles of the lower extremity and trunk.
Transmits the weight of the upper body and trunk to the ischial tuberosities during sitting and to the lower extremities during standing or walking.
Supports the organs of the bowel, bladder, and reproductive system.
Dr. Michael P. Gillespie

3. INNOMINATE
Ilium
Pubis
Ischium
Acetabulum
Dr. Michael P. Gillespie

4. EXTERNAL SURFACE OF THE PELVIS
Wing (ala) – the large fan-shaped wing of the ilium forms the superior half of the innominate.
Acetabulum – a deep, cup-shaped cavity below the wing.
Obturator-foramen – the largest foramen in the body. Covered by the obturator membrane.
Dr. Michael P. Gillespie

5. OSTEOLOGIC FEATURES OF THE ILIUM
External Surface
Posterior, anterior, and inferior gluteal lines
Anterior-superior iliac spine
Anterior-inferior iliac spine
Iliac crest
Posterior-superior iliac spine
Posterior-inferior iliac spine
Greater sciatic notch
Greater sciatic foramen
Sacrotuberous and sacrospinous ligaments
Internal Surface
Iliac fossa
Auricular surface
Iliac tuberosity
Dr. Michael P. Gillespie

6. OSTEOLOGIC FEATURES OF THE PUBIS
Superior pubic ramus
Body
Crest
Pectineal line
Pubic tubercle
Pubic symphysis joint and disc
Inferior pubic ramus
Dr. Michael P. Gillespie

7. OSTEOLOGIC FEATURES OF THE ISCHIUM
Ischial spine
Lesser sciatic notch
Lesser sciatic foramen
Ischial tuberosity
Ischial ramus
Dr. Michael P. Gillespie

8. ANTERIOR ASPECT: PELVIS, SACRUM, RIGHT PROXIMAL FEMUR
Dr. Michael P. Gillespie
FIGURE 12-1.   The anterior aspect of the pelvis, sacrum, and right proximal femur. Proximal attachments are indicated in red, distal attachments in gray. A section of the left side of the sacrum is removed to expose the auricular surface of the sacroiliac joint. The pelvic attachments of the capsule around the sacroiliac joint are indicated by dashed lines.

9. LATERAL VIEW RIGHT INNOMINATE BONE
Dr. Michael P. Gillespie
FIGURE 12-2.   A lateral view of the right innominate bone. Proximal attachments of muscle are indicated in red, distal attachments in gray.

10. POSTERIOR ASPECT OF PELVIS, SACRUM, & PROXIMAL FEMUR
Dr. Michael P. Gillespie
FIGURE 12-3.   The posterior aspect of the pelvis, sacrum, and right proximal femur. Proximal attachments of muscles are indicated in red, distal attachments in gray.

11. FEMUR The longest and strongest bone in the human body.
The femoral head projects medially and slightly anterior to articulate with the acetabulum.
The femoral neck connects the head with the shaft.
The neck displaces the proximal shaft of the femur laterally away from the joint, thereby reducing the likelihood of bony impingement.
Distal to the neck, the shaft of the femur courses slightly medially, placing the knees and feet closer to the midline of the body.
The femur bows slightly when subjected to the weight of the body. Stress along the bone is dissipated through compression along the posterior shaft and through tension along the anterior shaft.
Dr. Michael P. Gillespie

12. OSTEOLOGIC FEATURES OF THE FEMUR
Femoral Head
Femoral Neck
Intertrochanteric Line
Greater trochanter
Trochanteric fossa
Intertrochanteric crest
Quadrate tubercle
Lesser trochanter
Linea aspera
Pectineal (spiral) line
Gluteal tuberosity
Lateral and medial supracondylar lines
Adductor tubercle
Dr. Michael P. Gillespie

13. ANTERIOR ASPECT RIGHT FEMUR
Dr. Michael P. Gillespie
FIGURE 12-4.   The anterior aspect of the right femur. Proximal attachments of muscles are indicated in red, distal attachments in gray. The femoral attachments of the hip joint capsule and the knee joint capsule are indicated by dashed lines.

14. MEDIAL & POSTERIOR SURFACES RIGHT FEMUR
Dr. Michael P. Gillespie
FIGURE 12-5A-B.   The medial (A) and posterior (B) surfaces of the right femur. Proximal attachments of muscles are indicated in red, distal attachments in gray. The femoral attachments of the hip joint capsule and the knee joint capsule are indicated by dashed lines.

15. ANGLE OF INCLINATION
The angle of inclination of the proximal femur describes the angle within the frontal plane between the femoral neck and the medial side of the femoral shaft.
At birth this angle is about 140 – 150 degrees; however, the loading across the femoral neck during walking usually decreases this to the normal adult value of about 125 degrees.
Coxa = hip, vara = to bend inward, valga = to bend outward
Coxa vara – an angle of inclination markedly less than 125 degrees.
Coxa valga – an angle of inclination markedly greater than 125 degrees.
Abnormal angles can lead to dislocation or stress- induced degeneration of the joint.
Dr. Michael P. Gillespie

16. ANGLE OF INCLINATION Dr. Michael P. Gillespie
FIGURE 12-7.   The proximal femur is shown: A, normal angle of inclination; B, coxa vara; and C, coxa valga. The pair of red dots in each figure indicates the different alignments of the hip joint surfaces. Optimal alignment is shown in A.

17. FEMORAL TORSION
Femoral torsion describes the relative rotation (twist) between the bone’s shaft and neck.
Normally, as viewed from above, the femoral neck projects about 15 degrees anterior to a mid- lateral axis through the femoral condyles (normal anteversion).
Femoral torsion significantly different than 15 degrees is considered abnormal.
Excessive anteversion – significantly greater than 15 degrees
Retroversion – approaching 0 degrees
Healthy infants are born with about 40 degrees of femoral anteversion
Dr. Michael P. Gillespie

18. EXCESSIVE FEMORAL ANTEVERSION
Excessive anterversion that persists into adulthood can increase the likelihood of hip dislocation, articular incongruence, increase joint contact force, and increased wear on the cartilage.
This can lead to secondary osteoarthritis of the hip.
It may be associated with an abnormal gait pattern called “in- toeing”, a walking pattern with exaggerated posturing of hip internal rotation.
The amount of “in-toeing” is generally related to the amount of femoral anteversion.
It is a compensatory mechanism used to guide the excessively anteverted femoral head more directly into the acetabulum.
Over time, shortening of the internal rotator muscles and ligaments occurs, thereby reducing external rotation.
Most children with in-toeing eventually walk normally.
Excessive femoral anteversion is common in persons with cerebral palsy. It typically does not resolve in this population.
Dr. Michael P. Gillespie

19. NORMAL ANTEVERSION Dr. Michael P. Gillespie
FIGURE 12-8A.   The angle of torsion is shown between the neck and shaft of the femur: A, normal anteversion; B, excessive anteversion; and C, retroversion. The pair of red dots in each figure indicates the different alignments of the hip joint surfaces. Optimal alignment is shown in A.

20. EXCESSIVE ANTEVERSION
Dr. Michael P. Gillespie
FIGURE 12-8B.   The angle of torsion is shown between the neck and shaft of the femur: A, normal anteversion; B, excessive anteversion; and C, retroversion. The pair of red dots in each figure indicates the different alignments of the hip joint surfaces. Optimal alignment is shown in A.

21. RETROVERSION Dr. Michael P. Gillespie
FIGURE 12-8C.   The angle of torsion is shown between the neck and shaft of the femur: A, normal anteversion; B, excessive anteversion; and C, retroversion. The pair of red dots in each figure indicates the different alignments of the hip joint surfaces. Optimal alignment is shown in A.

22. INTERNAL ROTATION IMPROVING JOINT CONGRUITY
Dr. Michael P. Gillespie

23. IN-TOEING
Dr. Michael P. Gillespie

24. FUNCTIONAL ANATOMY OF THE HIP JOINT
The hip is a classic ball-and-socket joint secured within the acetabulum by an extensive set of connective tissues and muscles.
Articular cartilage, muscle, and cancellous bone in the proximal femur help dampen the large forces that cross the hip.
Dr. Michael P. Gillespie
FIGURE 12-9A-B.   Two situations show the same individual with excessive anteversion of the proximal femur. A, Offset red dots indicate malalignment of the hip while a subject stands in the anatomic position. B, As evidenced by the alignment of the red dots, standing with the hip internally rotated (“in-toeing”) improves the joint congruity.

25. FEMORAL HEAD
The head of the femur forms about two-thirds of a nearly perfect sphere.
The entire surface of the femoral head is covered by articular cartilage except for the region of the fovea, which is slightly posterior to the center of the head.
The fovea is a prominent pit that serves as the attachment point for the ligamentum teres.
The ligamentum teres is a tubular sheath that runs between the transverse acetabular ligament and the fovea of the femoral head. It is a sheath that contains the acetabular artery.
Dr. Michael P. Gillespie

26. ACETABULUM
The acetabulum (Latin – vinegar cup) is a deep, hemispheric cuplike socket that accepts the femoral head.
The femoral head contacts the acetabulum along the horseshoe-shaped lunate surface, which is covered with thick articular cartilage.
During walking, hip forces fluctuate from 13% of body weight to over 300% of body weight during the mid- stance phase.
During stance phase, the lunate surface flattens slightly as the acetabular notch widens. This serves as a dampening mechanism to reduce peak pressure.
The acetabular fossa is a depression located deep within the floor of the acetabulum. It does not normally come into contact with the femoral head.
Dr. Michael P. Gillespie

27. HIP JOINT COMPRESSION AS A PERCENT OF GAIT CYCLE
Dr. Michael P. Gillespie
FIGURE    Graph shows a computer model’s estimate of the hip joint compression force as a multiple of body weight during the gait cycle. The stance phase is between 0% and 60% of the gait cycle, and the swing phase is between 60% and 100% of the gait cycle (vertical stippled line separates these major divisions of the gait cycle). The images above the graph indicate the approximate area of acetabular contact at three selected magnitudes of hip joint force, estimated by data published in the literature. The area of joint contact increases from about 20% of the lunate surface during the swing phase to about 98% during mid stance phase.

28. ANATOMIC FEATURES OF THE HIP JOINT
Femoral Head
Fovea
Ligamentum teres
Acetabulum
Acetabular notch
Lunate surface
Acetabular fossa
Labrum
Transverse acetabular ligament
Dr. Michael P. Gillespie

29. INTERNAL ANATOMY OF HIP JOINT
Dr. Michael P. Gillespie
FIGURE    The right hip joint is opened to expose its internal components. The regions of thickest cartilage are highlighted (in blue) on the articular surfaces of the femoral head and acetabulum.

30. ACETABULAR LABRUM
The acetabular labrum is a flexible ring of fibrocartilage that surrounds the outer circumference (rim) of the acetabulum.
The acetabular labrum projects about 5 mm toward the femoral head.
It provides significant stability to the hip by “gripping” the femoral head and deepening the volume of the socket by approximately 30%.
The seal formed by the labrum maintains a negative intra- articular pressure, thereby creating a modest suction that resists distraction of the joint surfaces.
It also helps to hold synovial fluid within the joint space.
It decreases the contact stress (force / area) by increasing the surface area of the acetabulum.
Poor blood supply – limited ability to heal
Well supplied with afferent nerves – proprioceptive feedback / pain
Dr. Michael P. Gillespie

31. ACETABULAR ALIGNMENT
In the anatomic position, the acetabulum typically projects laterally from the pelvis with a varying amount of inferior and anterior tilt.
Congenital or developmental conditions can result in an abnormally shaped acetabulum.
A dysplastic acetabulum that does not adequately cover the femoral head can lead to chronic dislocation and increased stress, which can lead to osteoarthritis.
Two measurements are used to describe the extent to which the acetabulum naturally covers and helps to secure the femoral head:
Center-edge angle
Acetabular anteversion angle
Dr. Michael P. Gillespie

32. CENTER-EDGE ANGLE
The center-edge angle varies widely, but on average measures about 35 degrees in adults.
A significantly lower center-edge angle reduces the acetabular coverage of the femoral head. This increases the risk of dislocation and reduces contact area within the joint.
During the single-limb-support phase of walking, this reduced surface area would increase joint pressure (force / area) by about 50%.
This increased joint pressure can lead to premature osteoarthritis.
Dr. Michael P. Gillespie

33. CENTER-EDGE ANGLE Dr. Michael P. Gillespie
FIGURE 12-13A.   A, The center-edge angle measures the fixed orientation of the acetabulum within the frontal plane, relative to the pelvis. This measurement defines the extent to which the acetabulum covers the top of the femoral head. The center-edge angle is measured as the intersection of a vertical, fixed reference line (stippled) with the acetabular reference line (bold solid line) that connects the upper lateral edge of the acetabulum with the center of the femoral head. A more vertical acetabular reference line results in a smaller center-edge angle, providing less superior coverage of the femoral head. B, The acetabular anteversion angle measures the fixed orientation of the acetabulum within the horizontal plane, relative to the pelvis. This measurement indicates the extent to which the acetabulum covers the front of the femoral head. The angle is formed by the intersection of a fixed anterior-posterior reference line (stippled) with an acetabular reference line (bold solid line) that connects the anterior and posterior rim of the acetabulum. A larger acetabular anteversion angle creates less acetabular containment of the anterior side of the femoral head. (A normal femoral anteversion of 15 degrees is also shown.)

34. ACETABULAR ANTEVERSION ANGLE
The acetabular anteversion angle measures the extent to which the acetabulum projects anteriorly within the horizontal plane, relative to the pelvis.
Observed from above, the normal acetabular anteversion angle is about 20 degrees, which exposes part of the anterior side of the femoral head.
A hip with excessive acetabular anteversion is more exposed anteriorly.
When anteversion is severe, the hip is more prone to anterior dislocation and associated lesions of the labrum.
Dr. Michael P. Gillespie

35. ACETABULAR ANTEVERSION ANGLE
Dr. Michael P. Gillespie
FIGURE 12-13B.   A, The center-edge angle measures the fixed orientation of the acetabulum within the frontal plane, relative to the pelvis. This measurement defines the extent to which the acetabulum covers the top of the femoral head. The center-edge angle is measured as the intersection of a vertical, fixed reference line (stippled) with the acetabular reference line (bold solid line) that connects the upper lateral edge of the acetabulum with the center of the femoral head. A more vertical acetabular reference line results in a smaller center-edge angle, providing less superior coverage of the femoral head. B, The acetabular anteversion angle measures the fixed orientation of the acetabulum within the horizontal plane, relative to the pelvis. This measurement indicates the extent to which the acetabulum covers the front of the femoral head. The angle is formed by the intersection of a fixed anterior-posterior reference line (stippled) with an acetabular reference line (bold solid line) that connects the anterior and posterior rim of the acetabulum. A larger acetabular anteversion angle creates less acetabular containment of the anterior side of the femoral head. (A normal femoral anteversion of 15 degrees is also shown.)

36. CAPSULE AND LIGAMENTS OF THE HIP
A synovial membrane lines the internal surface of the hip joint capsule.
The iliofemoral, pubofemoral, and ischiofemoral ligaments reinforce the external surface of the capsule.
Passive tension in the stretched ligaments, the adjacent capsule, and the surrounding muscles help to define end-range movements of the hip.
Increasing the flexibility of parts of the capsule is an important component of manual physical therapy for restricted movement of the hip.
Dr. Michael P. Gillespie

37. ANTERIOR CAPSULE & LIGAMENTS
Dr. Michael P. Gillespie
FIGURE    The anterior capsule and ligaments of the right hip. The iliopsoas is cut to expose the anterior side of the joint. Note that part of the femoral head protrudes just medial to the iliofemoral ligament. This region may be covered by a bursa.

38. POSTERIOR CAPSULE & LIGAMENTS
Dr. Michael P. Gillespie
FIGURE    The posterior capsule and ligaments of the right hip.

39. PARAPLEGIC WITH SUPPORT BRACES
Dr. Michael P. Gillespie
FIGURE    A person with paraplegia is shown standing with the aid of braces at the knees and ankles. Leaning the pelvis and trunk posteriorly orients the body weight vector (red arrow) posterior to the hip joints (small green circle), thereby stretching the iliofemoral ligaments. This stretch provides a passive flexion torque at the hip, which helps to balance the extension torque generated by gravity. Once counterbalanced, these opposing torques can stabilize the pelvis and trunk, relative to the femur, during standing. (Modified from Somers MF: Spinal cord injury: functional rehabilitation, Norwalk, 1992, Appleton & Lange.)

40. TISSUES THAT BECOME TAUT AT THE END-RANGES OF PASSIVE HIP MOTION
End-Range Position
Taut Tissue
Hip flexion (knee extended)
Hamstrings
Hip flexion (knee flexed)
Inferior and posterior capsule; gluteus maximus
Hip extension (knee extended)
Primarily iliofemoral ligament, some fibers of the pubofemoral and ischiofemoral ligaments; psoas major
Hip extension (knee flexed)
Rectus femoris
Dr. Michael P. Gillespie

41. TISSUES THAT BECOME TAUT AT THE END-RANGES OF PASSIVE HIP MOTION
End-Range Position
Taut Tissue
Abduction
Pubofemoral ligament; adductor muscles
Adduction
Superior fibers of ischiofemoral ligament; iliotibial band; and abductor muscles such as the tensor fascia latae and gluteus maximus
Internal rotation
Ischiofemoral ligament; external rotator muscles, such as the piroformis or gluteus maximus
External rotation
Iliofemoral and pubofemoral ligaments; internal rotator muscles, such as the tensor fascia latae or gluteus minimus
Dr. Michael P. Gillespie

42. CLOSE-PACKED POSITION OF THE HIP
Full extension of the hip (about 20 degrees beyond neutral) in conjunction with slight internal rotation and slight abduction twists or “spirals” the fibers of the capsular ligaments to their most taut position.
This is considered the close-packed position of the hip.
The passive tension leads to stability of the joint and reduces “joint play”.
The hip joint is one of the few joints in the body where the close-packed position is NOT also the position of maximal joint congruency. They fit most congruently in about 90 degrees of flexion, moderate abduction, and external rotation.
Dr. Michael P. Gillespie

43. NEUTRAL AND CLOSED PACKED POSITIONS
Dr. Michael P. Gillespie
FIGURE    A, The hip is shown in a neutral position, with all three capsular ligaments identified. B, Superior view of the hip in its close-packed position (i.e., fully extended with slight abduction and internal rotation). This position elongates at least some component of all three capsular ligaments.

44. OSTEOKINEMATICS
Reduced hip motion may be an early indicator of disease or trauma.
Limited hip motion can impose functional limitations on activities such as walking, standing upright, or picking up objects on the floor.
Femoral-on-pelvic hip osteokinematics – rotation of the femur about a relatively fixed pelvis.
Pelvic-on-femoral hip osteokinematics – rotation of the pelvis, and often the superimposed trunk, over relatively fixed femurs.
Movements:
flexion & extension in the sagittal plane, abduction & adduction in the frontal plane, and internal and external rotation in the horizontal plane.
The anatomic position is the 0-degree or neutral reference point.
Dr. Michael P. Gillespie

45. FEMORAL-ON-PELVIC OSTEOKINEMATICS
Rotation of the Femur in the Sagittal Plane
Hip flexion to 120 degrees
Full knee extension limits hip flexion to 70 – 80 degrees due to increased tension in the hamstrings
Hip extension to 20 degrees
Full knee flexion reduces hip extension due to tension in rectus femoris
Rotation of the Femur in the Frontal Plane
Hip abduction to 40 degrees
Limited by pubofemoral ligament and adductors
Hip adduction to 25 degrees
Limited by interference with contralateral limb, passive tension in hip abductors, iliotibial band, and ischiofemoral ligament
Rotation of the Femur in the Horizontal Plane
Internal rotation to 35 degrees
Produces tension in piriformis and ischiofemoral ligament
External rotation to 45 degrees
Produces tension in internal rotators and iliofemoral ligament
Dr. Michael P. Gillespie

46. SAGITTAL PLANE ROTATIONS
Dr. Michael P. Gillespie
FIGURE 12-19A.   The osteokinematics of the right hip joint. Femoral-on-pelvic and pelvic-on-femoral rotations occur in three planes. The axis of rotation for each plane of movement is shown as a colored dot, located at the center of the femoral head. A, Side view shows sagittal plane rotations around a medial-lateral axis of rotation. B, Front view shows frontal plane rotations around an anterior-posterior axis of rotation. C, Top view shows horizontal plane rotations around a longitudinal, or vertical, axis of rotation.

47. FRONTAL PLANE ROTATIONS
Dr. Michael P. Gillespie
FIGURE 12-19B.   The osteokinematics of the right hip joint. Femoral-on-pelvic and pelvic-on-femoral rotations occur in three planes. The axis of rotation for each plane of movement is shown as a colored dot, located at the center of the femoral head. A, Side view shows sagittal plane rotations around a medial-lateral axis of rotation. B, Front view shows frontal plane rotations around an anterior-posterior axis of rotation. C, Top view shows horizontal plane rotations around a longitudinal, or vertical, axis of rotation.

48. HORIZONTAL PLANE ROTATIONS
Dr. Michael P. Gillespie
FIGURE 12-19C.   The osteokinematics of the right hip joint. Femoral-on-pelvic and pelvic-on-femoral rotations occur in three planes. The axis of rotation for each plane of movement is shown as a colored dot, located at the center of the femoral head. A, Side view shows sagittal plane rotations around a medial-lateral axis of rotation. B, Front view shows frontal plane rotations around an anterior-posterior axis of rotation. C, Top view shows horizontal plane rotations around a longitudinal, or vertical, axis of rotation.

49. FEMORAL-ON-PELVIC (HIP) MOTION
Dr. Michael P. Gillespie
FIGURE    The near maximal range of femoral-on-pelvic (hip) motion is depicted in the sagittal plane (A), frontal plane (B), and horizontal plane (C). Tissues that are elongated or pulled taut are indicated by straight black or dashed black arrows. Slackened tissue is indicated by a wavy black arrow.

50. PELVIC-ON-FEMORAL OSTEOKINEMATICS
Pelvic rotation in the Sagittal Plane
Pelvic rotation in the Frontal Plane
Pelvic Rotation in the Horizontal Plane
Dr. Michael P. Gillespie

51. LUMBOPELVIC RHYTHM
The caudal end of the axial skeleton is firmly attached to the pelvis by way of the sacroiliac joints.
Rotation of the pelvis over the femoral heads typically changes the configuration of the lumbar spine.
This is referred to as lumbopelvic rhythm.
Ipsidirectional lumbopelvic rhythm.
The pelvis and lumbar spine rotate in the same direction.
Contradirectional lumbopelvic rhythm.
The pelvis and lumbar spine rotate in opposite directions.
Dr. Michael P. Gillespie

52. LUMBOPELVIC RHYTHMS Dr. Michael P. Gillespie
FIGURE 12-21A-B.   Two contrasting types of lumbopelvic rhythms used to rotate the pelvis over fixed femurs. A, An “ipsidirectional” rhythm describes a movement in which the lumbar spine and pelvis rotate in the same direction, thus amplifying overall trunk motion. B, A “contradirectional” rhythm describes a movement in which the lumbar spine and pelvis rotate in opposite directions.

53. PELVIC ROTATION IN THE SAGITTAL PLANE: ANTERIOR AND POSTERIOR PELVIC TILTING
Pelvic Tilt – a short-arc, sagittal rotation of the pelvis relative to stationary femurs.
Anterior Pelvic Tilt
Increase in lumbar curvature offsets the tendency of the supralumbar trunk to follow the forward rotation
30 degrees
Posterior Pelvic Tilt
Decrease in lumbar curvature
15 degrees
Dr. Michael P. Gillespie

54. PELVIC ROTATION IN THE FRONTAL PLANE
Pelvic-on-femoral rotation in the frontal and horizontal planes is best described assuming a person is standing on one limb. The weight bearing extremity is referred to as the support hip.
Abduction of the support hip occurs by raising or “hiking” the iliac crest on the side of the nonsupport hip.
The lumbar spine must bend in the direction opposite the rotating pelvis.
Slight lateral convexity within the lumbar region toward the side of the abducting hip.
30 degrees of abduction
Adduction of the support hip occurs by a lowering of the iliac crest on the side of the nonsupport hip.
Slight lateral concavity within the lumbar region of the side of the adducted hip.
Dr. Michael P. Gillespie

55. PELVIC ROTATION IN THE HORIZONTAL PLANE
Pelvic-on-femoral rotation in the frontal and horizontal planes is best described assuming a person is standing on one limb. The weight bearing extremity is referred to as the support hip.
Internal rotation of the support hip occurs as the iliac crest on the side of the nonsupport hip rotates forward in the horizontal plane.
External rotation of the support hip occurs as the iliac crest on the side of the nonsupport hip rotates backward in the horizontal plane.
Dr. Michael P. Gillespie

56. PELVIC-ON-FEMORAL (HIP) MOTION
Dr. Michael P. Gillespie
FIGURE    The near-maximal range of pelvic-on-femoral (hip) motion is shown in the sagittal plane (A), frontal plane (B), and horizontal plane (C). The motion assumes that the supralumbar trunk remains nearly stationary during the hip motion (i.e., kinematics based on a contradirectional lumbopelvic rhythm). The large colored and black arrows depict pelvic rotation and the associated “offsetting” lumbar motion. Tissues that are elongated or pulled taut are indicated by thin, straight black arrows; tissues slackened are indicated by thin wavy black arrows. The range of motions depicted in each figure has been estimated by observing photographs of healthy young adults.

57. ARTHROKINEMATICS
During hip motion, the nearly spherical femoral head normally remains snugly seated within the confines of the acetabulum.
Hip arthrokinematics are based upon traditional convex-on-concave or concave-on-convex principles.
Dr. Michael P. Gillespie

58. MOTOR INNERVATION Lumbar Plexus Sacral Plexus Femoral nerve (L2-L4)
Obturator nerve (L2-L4)
Sacral Plexus
Nerve to piriformis (S1-S2)
Nerve to obturator internus and gemullus superior (L5-S2)
Nerve to quadratus femoris and gemullus inferior (L4-S1)
Superior gluteal nerve (L4-S1)
Inferior gluteal nerve (L5-S2)
Sciatic nerve (L4-S3), including tibial and common fibular (peroneal) portions
Dr. Michael P. Gillespie

59. SENSORY INNERVATION
As a general rule, the hip capsule, ligaments, and parts of the labrum receive sensory innervation through the same nerve roots that supply the overlying muscles.
The anterior part of the capsule of the hip receives sensory fibers from the femoral nerve.
The posterior capsule receives sensory fibers from all nerve roots originating from the sacral plexus.
The connective tissues of the medial aspects of the hip and knee joints receive sensory fibers from the obturator nerve (Inflammation of the hip may be perceived as pain in the medial knee region).
Dr. Michael P. Gillespie

60. OBTURATOR NERVE Dr. Michael P. Gillespie
FIGURE 12-24A.   The path and general proximal-to-distal order of muscle innervation for the femoral and obturator nerves (A) and the sciatic nerve (B). The locations of certain muscles are altered slightly for clarity. The spinal nerve roots for each nerve are shown in parenthesis. The drawing on the right side of A shows the sensory distribution of cutaneous branches of the femoral and obturator nerves. (Modified from deGroot J: Correlative neuroanatomy, ed 21, Norwalk, 1991, Appleton & Lange.)

61. SCIATIC NERVE Dr. Michael P. Gillespie
FIGURE 12-24B.   The path and general proximal-to-distal order of muscle innervation for the femoral and obturator nerves (A) and the sciatic nerve (B). The locations of certain muscles are altered slightly for clarity. The spinal nerve roots for each nerve are shown in parenthesis. The drawing on the right side of A shows the sensory distribution of cutaneous branches of the femoral and obturator nerves. (Modified from deGroot J: Correlative neuroanatomy, ed 21, Norwalk, 1991, Appleton & Lange.)

62. MUSCULAR FUNCTION AT THE HIP
Dr. Michael P. Gillespie

63. MUSCLES OF THE HIP, ORGANIZED ACCORDING TO PRIMARY OR SECONDARY ACTIONS
Flexors
Adductors
Internal Rotators
Extensors
Abductors
External Rotators
Primary
Iliopsoas
Sartorius
TFL
Rectus femoris
Adductor longus
Pectineus
Gracilis
Adductor brevis
Adductor magnus
Not applicable
Gluteus maximus
Biceps femoris (long head)
Semitendinosus
Semimembranosus
Adductor magnus (posterior head)
Gluteus medius
Gluteus minimus
Piriformis
Obturator internus
Gemellus superior
Gemellus inferior
Quadratus femoris
Secondary
Gluteus minimus (anterior fibers)
Gluteus maximus (lower fibers)
Gluteus medius (anterior fibers)
Gluteus medius (posterior fibers)
Adductor magnus (anterior head)
Gluteus minimus (posterior fibers)
Obturator externus
Dr. Michael P. Gillespie

64. MUSCLES OF THE ANTERIOR HIP
Dr. Michael P. Gillespie
FIGURE    Muscles of the anterior hip region. The right side of the body shows flexors and adductor muscles. Many muscles on the left side are cut to expose the adductor brevis and adductor magnus.

65. HIP FLEXOR MUSCLES
The primary hip flexors are the iliopsoas, sartorius, tensor fascia latae, rectus femoris, adductor longus, and pectineus.
Secondary hip flexors are adductor brevis, gracilis, and anterior fibers of the gluteus minimus.
Dr. Michael P. Gillespie

66. PELVIC-ON-FEMORAL HIP FLEXION: ANTERIOR PELVIC TILT
The anterior pelvic tilt is performed by a force- couple between the hip flexor and low back extensor muscles.
Dr. Michael P. Gillespie

67. FORCE COUPLE FOR ANTERIOR PELVIC TILT
Dr. Michael P. Gillespie
FIGURE    The force couple is shown between two representative hip flexor muscles and the erector spinae to anteriorly tilt the pelvis. The moment arms for the erector spinae and sartorius are indicated by the dark black lines. Note the increased lordosis at the lumbar spine.

68. FEMORAL-ON-PELVIC HIP FLEXION
Femoral-on-pelvic hip flexion often occurs simultaneously with knee flexion as a means to shorten the functional length of the lower extremity during the swing phase of walking or running.
Moderate to high power hip flexion requires coactivation of the hip flexor and abdominal muscles.
Rectus abdominus must create a strong posterior pelvic tilt to neutralize the strong anterior pelvic tilt potential of the hip flexors.
Dr. Michael P. Gillespie

69. STABILIZING ROLE OF ABDOMINALS WITH UNILATERAL LEG RAISING
Dr. Michael P. Gillespie
FIGURE 12-28A-B.   The stabilizing role of the abdominal muscles is shown during a unilateral straight-leg-raise. A, With normal activation of the abdominal muscles (such as the rectus abdominis), the pelvis is stabilized and prevented from anterior tilting by the inferior pull of the hip flexor muscles. B, With reduced activation of the rectus abdominis, contraction of the hip flexor muscles causes a marked anterior tilt of the pelvis. Note the increase in lumbar lordosis that accompanies the anterior tilt of the pelvis. The reduced activation in the abdominal muscle is indicated by the lighter red.

70. HIP ADDUCTOR MUSCLES
The primary adductors of the hip are the pectineus, adductor longus, gracilis, adductor brevis, and adductor magnus.
Secondary adductors are the biceps femoris (long head), the gluteus maximus (especially lower fibers) and the quadratus femoris.
Dr. Michael P. Gillespie

71. HIP ADDUCTORS Dr. Michael P. Gillespie
FIGURE    The anatomic organization and proximal attachments of the adductor muscle group.

72. BILATERAL COOPERATIVE ACTION OF ADDUCTORS
Dr. Michael P. Gillespie
FIGURE    The bilateral cooperative action of selected adductor muscles while a soccer ball is kicked. The left adductor magnus is shown actively producing pelvic-on-femoral adduction. Several right adductor muscles are shown actively producing femoral-on-pelvic adduction torque, needed to accelerate the ball.

73. DUAL ACTION OF ADDUCTOR LONGUS
Dr. Michael P. Gillespie
FIGURE    The dual sagittal plane action of the adductor longus muscle is demonstrated during sprinting. A, With the hip flexed, the adductor longus is in position to extend the hip, along with the adductor magnus. B, With hip extended, the adductor longus is in position to flex the hip, along with the rectus femoris. These contrasting actions are based on the change in line of force of the adductor longus, relative to the medial-lateral axis of rotation at the hip.

74. HIP INTERNAL ROTATORS: OVERALL FUNCTION
There are no primary internal rotators of the hip because no muscle is oriented close to the horizontal plane.
Secondary internal rotators are the anterior fibers of the gluteus minimus and gluteus medius, tensor fasciae latae, adductor longus, adductor brevis, and pectineus.
Dr. Michael P. Gillespie

75. HORIZONTAL PLANE LINES OF FORCE OF SEVERAL MUSCLES THAT CROSS THE HIP
Dr. Michael P. Gillespie
FIGURE    A superior view depicts the horizontal plane line of force of several muscles that cross the hip. The longitudinal axis of rotation is in the superior-inferior direction through the femoral head. For clarity, the tensor fasciae latae and sartorius muscles are not shown. The external rotators are indicated by solid lines and the internal rotators by dashed lines. (The actual scale of the image is indicated on the vertical and horizontal axes of the graph.)

76. ADDUCTORS AS INTERNAL ROTATORS
Dr. Michael P. Gillespie
FIGURE    The adductor muscles as secondary internal rotators of the hip. A, Because of the anterior bowing of the femoral shaft, a large segment of the linea aspera (short red line) runs anterior to the longitudinal axis of rotation (blue rod). B, A superior view of the right hip shows the horizontal line of force of the adductor longus. The muscle causes an internal rotation torque by producing a force that passes anterior to the axis of rotation (small blue circle at femoral head). The moment arm used by the adductor longus is indicated by the thick dark line. The oval set of dashed black lines represents the outline of the midshaft of the femur at the region of the distal attachment of the adductor longus.


77. HIP EXTENSOR MUSCLES
The primary hip extensors are the gluteus maximus, the hamstrings (long head of the biceps femoris, semitendinosus, semimembranosus), and the posterior head of the adductor magnus.
Secondary extensors are the posterior fibers of the gluteus medius and the anterior fibers of the adductor magnus.
Dr. Michael P. Gillespie

78. POSTERIOR MUSCLES OF THE HIP
Dr. Michael P. Gillespie
FIGURE    The posterior muscles of the hip. The left side highlights the gluteus maximus and hamstring muscles (long head of the biceps femoris, semitendinosus, and semimembranosus). The right side shows the hamstring muscles cut to expose the adductor magnus and short head of the biceps femoris. The right side shows the gluteus medius and five of the six short external rotators (i.e., piriformis, gemellus superior and inferior, obturator internus, and quadratus femoris).

79. PELVIC-ON-FEMORAL HIP EXTENSION PERFORMING A POSTERIOR PELVIC TILT
Hip extensors performing a posterior pelvic tilt.
The hip extensors and the abdominal muscles act as a force couple to posteriorly tilt the pelvis.
Hip extensors controlling a forward lean of the body.
The muscular support for this activity is primarily the responsibility of the hamstrings.
Dr. Michael P. Gillespie

80. FORCE COUPLE FOR POSTERIOR PELVIC TILT
Dr. Michael P. Gillespie
FIGURE    The force couple between representative hip extensors (gluteus maximus and hamstrings) and abdominal muscles (rectus abdominis and obliquus externus abdominis) used to posteriorly tilt the pelvis. The moment arms for each muscle group are indicated by the dark black line. Note the decreased lordosis at the lumbar spine. The extension at the hip stretches the iliofemoral ligament.

81. HIP EXTENSORS CONTROLLING A FORWARD LEAN OF THE BODY
Dr. Michael P. Gillespie
FIGURE    The hip extensor muscles are shown controlling a forward lean of the pelvis over the thighs. A, Slight forward lean of the upper body displaces the body weight force slightly anterior to the medial-lateral axis of rotation at the hip. B, A more significant forward lean displaces the body weight force even farther anteriorly. The greater flexion of the hips rotates the ischial tuberosities posteriorly, thereby increasing the hip extension moment arm of the hamstrings. The taut line (with arrow head within the stretched hamstring muscles) indicates the increased passive tension. In both A and B, the relative demands placed on the muscles are shown by relative shades of red. At right is a graph showing the length of hip extension moment arms of selected hip extensors as a function of forward lean.

82. FEMORAL-ON-PELVIC HIP EXTENSION
Hip extensor muscles are required to produce large and powerful femoral-on-pelvic hip extension torque to accelerate the body forward and upward (i.e. climbing a hill).
Dr. Michael P. Gillespie

83. HIP EXTENSOR ENGAGEMENT WHILE CLIMBING
Dr. Michael P. Gillespie
FIGURE    Relatively high demands are placed on hip extensor muscles while one climbs a mountain supporting an external load. Activation is also required in low-back extensor muscles (such as, for example, the lower multifidus) to stabilize the position of the pelvis.

84. FULLY EXTENDABLE HIP
Dr. Michael P. Gillespie

85. EFFECTS OF HIP FLEXION CONTRACTURE ON THE BIOMECHANICS OF STANDING
Dr. Michael P. Gillespie
FIGURE 12-30A-B.   The effect of a hip flexion contracture on the biomechanics of standing. A, Ideal standing posture. B, Attempts at standing upright with a hip flexion contracture. Hip extensor muscles are shown active (in red) to varying magnitudes to prevent further hip flexion. The moment arms used by the muscles and body weight are indicated as short black lines originating at the hip’s axis of rotation. In A and B, the green dot at the center of the femoral head represents the axis of rotation. The pair of red circles denotes the overlap of the relatively thicker areas of articular cartilage. (From Neumann DA: An arthritis home study course. The synovial joint: anatomy, function, and dysfunction. LaCrosse, Wisc, 1998, Orthopaedic Section of the American Physical Therapy Association.)

86. HIP ABDUCTOR MUSCLES
The primary hip abductor muscles are the gluteus medius, gluteus minimus, and tensor fasciae latae.
Secondary abductors are the piriformis and sartorius.
Dr. Michael P. Gillespie

87. DEEP MUSCLES OF POSTERIOR & LATERAL HIP
Dr. Michael P. Gillespie
FIGURE    Deep muscles of the posterior and lateral hip region. The gluteus medius and the gluteus maximus are cut to expose deeper muscles.

88. ABDUCTOR CONTROL OF FRONTAL PLANE STABILITY OF THE PELVIS WHILE WALKING
The abduction torque produced by the hip abductor muscles is essential to the control of the frontal plane pelvic-on-femoral kinematics during walking.
The abduction torque produced by hip abductor muscles is particularly important during the single-limb-support phase of gait.
The abduction torque on the stance limb prevents the pelvis and trunk from dropping uncontrollably toward the side of the swinging limb.
Dr. Michael P. Gillespie

89. ABDUCTOR ROLE IN THE PRODUCTION OF COMPRESSION FORCE AT THE HIP
During single-limb support, the hip abductor muscles (esp. gluteus medius) produce most of the compression force across the hip.
The hip abductor muscles must produce a force that is twice that of body weight in order to achieve stability during single-limb support.
Dr. Michael P. Gillespie

90. GREATER TROCHANTERIC PAIN SYNDROME
Excessive or repetitive action of the gluteus medius and minimus can cause point tenderness adjacent to the greater trochanter (the primary distal attachment of these muscles).
This painful response suggests inflammation within the hip abductor mechanism.
Pain associated with activation of the hip abductor mechanism can be disabling considering the frequent and relatively large demands placed upon these muscles during the single-limb-support phase of the gait cycle.
Pain can be due to inflammation of the bursa associated with the distal attachments or with tears of the distal tendons.
The term greater trochanteric pain syndrome describes this condition.
Dr. Michael P. Gillespie

91. HIP ABDUCTOR MUSCLE WEAKNESS
Several conditions are associated with weakness of the hip abductor muscles.
Muscular dystrophy, Guillian-Barre syndrome, spinal cord injury, greater trochanteric pain syndrome, hip osteoarthritis or rheumatoid arthritis, poliomyelitis, and undefined hip pain or weakness.
The classic indicator of hip abductor weakness is the positive Trendelenburg sign.
The patient is asked to stand in single-limb support over the weak hip.
A positive sign occurs if the pelvis drops to the side of the unsupported limb. The weak hip “falls” into pelvic-on-femoral adduction.
Dr. Michael P. Gillespie

92. HIP EXTERNAL ROTATOR MUSCLES
The primary external rotator muscles of the hip are the gluteus maximus and five of the six “short external rotators”.
Secondary external rotators are the posterior fibers of gluteus medius and minimus, obturator externus, sartorius, and long head of biceps femoris.
Dr. Michael P. Gillespie

93. OBTURATOR INTERNUS Dr. Michael P. Gillespie
FIGURE    Superior view depicts the orientation and action of the obturator internus muscle. A, While one stands at rest, the obturator internus muscle makes a 130-degree deflection as it courses through the pulley formed by the lesser sciatic notch. B, With the femur fixed during standing, contraction of this muscle causes pelvic-on-femoral (hip) external rotation. (The external rotation of the hip is apparent by the reduced distance between the posterior side of the greater trochanter and the lateral side of the pelvis.) Note the compression force generated into the joint as the result of the muscle contraction.

94. FUNCTIONAL ANATOMY OF THE “SHORT EXTERNAL ROTATORS”
The six “short external rotators” of the hip are the piriformis, obturator internus, gemellus superior, gemellus inferior, quadratus femoris, and obturator externus.
Dr. Michael P. Gillespie

95. EXTERNAL ROTATORS OVERALL FUNCTION
The functional potential of the external rotators is most evident during pelvic-on-femoral rotation.
The action of planting a foot and “cutting” to the opposite side is the natural way to abruptly change direction while running.
Dr. Michael P. Gillespie

96. EXTERNAL ROTATOR ACTION
Dr. Michael P. Gillespie
FIGURE    Action of the right external rotator muscles during pelvic-on-femoral external rotation of the right hip. Back extensor muscles are also shown rotating the lower trunk to the left.

97. FRACTURE OF THE HIP
Fracture of the hip (i.e. proximal femur) is a major health and economic problem in the United States.
About 95% of all fractures of the hip are the result of falls.
It is the 2nd leading cause of hospitalization in the elderly.
Age related osteoporosis and a higher incidence of falling are reasons for a higher incidence of hip fracture in the elderly.
Mortality is surprisingly high after hip fracture: studies report 12% to 25% of persons die within 1 year of fracturing a hip.
Only about 40% of persons are able to independently perform their basic functional activities 6 to 12 months after hip fracture.
About half of those persons continue to require an assistive device to aid their walking.
Dr. Michael P. Gillespie

98. OSTEOARTHRITIS OF THE HIP
Hip osteoarthritis is a disease manifested by deterioration of the joint’s articular cartilage, loss of joint space, sclerosis of subchondral bone, and the presence of osteophytes.
Dr. Michael P. Gillespie

99. EFFECTS OF COXA VARA & COXA VALGA
Dr. Michael P. Gillespie
FIGURE    The negative and positive biomechanical effects of coxa vara and coxa valga are contrasted. As a reference, a hip with a normal angle of inclination (α = 125 degrees) is shown in the center of the display. D is the internal moment arm used by hip abductor force; I is the bending moment arm across the femoral neck.