Hip Joint

Quick Reference

Property	Details
Joint Type	Ball-and-socket (synovial)
Bones	Femoral head, acetabulum of pelvis
Degrees of Freedom	3 (triaxial)
Key Ligaments	Iliofemoral (Y ligament of Bigelow), pubofemoral, ischiofemoral, ligamentum teres
Key Structures	Acetabular labrum, joint capsule, greater/lesser trochanters
Primary Movements	Flexion, extension, abduction, adduction, internal rotation, external rotation

Anatomy

The hip joint is a deep ball-and-socket articulation between the femoral head and the acetabulum of the pelvis. Unlike the shoulder, which prioritizes mobility, the hip emphasizes stability through its deep socket and robust ligamentous support.

The acetabulum is a deep, cup-shaped socket that covers approximately 40% of the femoral head, providing inherent bony stability. The acetabular labrum, a fibrocartilaginous rim, deepens the socket by an additional 20% and creates negative intra-articular pressure that resists distraction forces.

The ligamentum teres is a small ligament running from the fovea of the femoral head to the acetabular notch. While it contributes minimal mechanical stability, it carries the artery of the ligamentum teres, which supplies blood to the femoral head (particularly important in children).

The hip capsule is the strongest in the body, reinforced by three major ligaments:

• Iliofemoral ligament (Y ligament): The strongest ligament in the body, preventing excessive extension
• Pubofemoral ligament: Limits abduction and external rotation
• Ischiofemoral ligament: Restricts internal rotation and adduction

These ligaments spiral around the femoral neck and tighten in extension, allowing humans to stand upright with minimal muscular effort.

Range of Motion

Movement	Normal ROM	Limiting Factors
Flexion	120-125° (knee bent) 90° (knee straight)	Hamstring tension (knee straight), anterior thigh-abdomen contact, posterior capsule
Extension	10-15°	Iliofemoral ligament (primary), hip capsule, hip flexor tension
Abduction	45-50°	Pubofemoral ligament, adductor muscle tension, opposite leg contact
Adduction	20-30°	Iliotibial band, opposite leg interference, lateral hip structures
Internal Rotation	30-40°	Ischiofemoral ligament, posterior capsule, external rotator tension
External Rotation	45-50°	Pubofemoral ligament, iliofemoral ligament, internal rotator tension

Note: ROM varies significantly with hip position. Flexion allows greater rotation; extension restricts rotation due to capsular tightening.

Joint Actions

Flexion

Primary Movers:

• Iliopsoas (most powerful hip flexor)
• Rectus femoris
• Sartorius

Synergists:

• Tensor fasciae latae
• Pectineus
• Adductor longus/brevis (with flexion)

Functional Notes: Hip flexion is critical for walking, running, climbing stairs, and sitting. The iliopsoas is most effective when the hip is extended; rectus femoris contributes more when the knee is flexed.

Extension

Primary Movers:

• Gluteus maximus (most powerful extensor)
• Hamstrings (biceps femoris, semitendinosus, semimembranosus)

Synergists:

• Adductor magnus (posterior fibers)
• Posterior fibers of gluteus medius/minimus

Functional Notes: Hip extension is essential for standing from sitting, climbing, and powerful movements like sprinting and jumping. The gluteus maximus is preferentially recruited during high-force activities.

Abduction

Primary Movers:

• Gluteus medius (primary stabilizer)
• Gluteus minimus

Synergists:

• Tensor fasciae latae
• Piriformis (when hip is neutral or flexed)
• Sartorius

Functional Notes: Hip abductors are critical for single-leg stance stability, preventing pelvic drop (Trendelenburg gait). They work eccentrically to control pelvic motion during walking and running.

Adduction

Primary Movers:

• Adductor magnus
• Adductor longus
• Adductor brevis
• Gracilis

Synergists:

• Pectineus
• Lower fibers of gluteus maximus

Functional Notes: Adductors stabilize the pelvis, control lateral movements, and are heavily involved in change-of-direction activities. They also assist with hip flexion (anterior fibers) and extension (posterior adductor magnus).

Rotation

Internal Rotators:

• Tensor fasciae latae
• Anterior fibers of gluteus medius/minimus
• Adductor longus/brevis/magnus

External Rotators:

• Piriformis
• Obturator internus/externus
• Gemellus superior/inferior
• Quadratus femoris
• Gluteus maximus

Functional Notes: External rotators (deep six) are critical for hip stability and controlling femoral internal rotation during gait. Weakness contributes to dynamic knee valgus and increased injury risk.

Muscles Acting On It

Muscle Group	Prime Movers	Synergists	Stabilizers
Hip Flexors	Iliopsoas, rectus femoris	Sartorius, TFL, pectineus	Deep abdominals
Hip Extensors	Gluteus maximus, hamstrings	Adductor magnus (posterior)	Erector spinae, multifidus
Hip Abductors	Gluteus medius, gluteus minimus	TFL, piriformis	Quadratus lumborum, obliques
Hip Adductors	Adductor magnus/longus/brevis	Gracilis, pectineus	Transversus abdominis
External Rotators	Deep six (piriformis, obturators, gemelli, quadratus femoris)	Gluteus maximus, sartorius	Pelvic floor
Internal Rotators	TFL, anterior glute med/min	Adductors	-

Mobility Work

Dynamic Mobility

90/90 Hip Rotations:

• Sit with front leg at 90° (external rotation), back leg at 90° (internal rotation)
• Lean forward over front shin to load external rotation
• Switch sides to train both rotation patterns
• Progression: Lift front knee off ground

Hip Circles/CARs (Controlled Articular Rotations):

• Standing or quadruped position
• Move through complete hip ROM in circular pattern
• Maintain neutral spine, control movement speed
• Both directions, emphasizing end-ranges

Walking Spiderman with Rotation:

• Lunge position with hands on ground
• Rotate torso toward front leg
• Alternate sides while moving forward

Static Stretching

Pigeon Pose:

• Front leg in hip external rotation and flexion
• Back leg extended (targets hip flexors)
• Emphasizes external rotation ROM and hip flexor length

Couch Stretch:

• Rear foot elevated on wall/couch
• Front foot forward in lunge
• Upright torso to maximize hip extension stretch
• Targets iliopsoas, rectus femoris, hip capsule

90/90 Hip Stretch:

• Seated position with controlled hip rotation angles
• Systematic exploration of internal/external rotation limitations

Joint Mobilizations

Hip Capsule Distraction:

• Band around hip crease
• Move into end-range positions while maintaining distraction
• Targets capsular restrictions

Hip Flexion with Compression:

• Supine with band creating anterior-posterior glide
• Pull knee to chest while band pulls femur posteriorly
• Improves flexion ROM and joint mechanics

Common Issues

Femoroacetabular Impingement (FAI)

Types:

• Cam impingement: Abnormal femoral head shape (not perfectly spherical)
• Pincer impingement: Excessive acetabular coverage
• Mixed: Combination of both

Symptoms: Anterior hip/groin pain with flexion and internal rotation, difficulty with deep squatting, prolonged sitting discomfort.

Management: Activity modification, hip mobility work avoiding impingement positions, strengthening hip stabilizers, surgical intervention for structural cases.

Labral Tears

Mechanism: Repetitive impingement, trauma, degenerative changes, or structural abnormalities (FAI).

Symptoms: Deep hip/groin pain, catching or locking sensation, pain with prolonged sitting or pivoting movements.

Management: Conservative: Load management, avoid aggravating movements, strengthen hip stabilizers. Surgical: Labral repair or debridement for mechanical symptoms.

Hip Bursitis

Types:

• Trochanteric bursitis: Lateral hip pain, often from ITB friction or direct trauma
• Iliopsoas bursitis: Anterior hip pain, clicking with hip flexion/extension

Management: Reduce compression (avoid side-lying on affected hip, ITB rolling), address biomechanical factors (glute weakness, hip drop), gradual loading progression.

Snapping Hip Syndrome

Types:

• External: ITB or gluteus maximus snapping over greater trochanter
• Internal: Iliopsoas tendon snapping over iliopectineal eminence or femoral head
• Intra-articular: Labral tear, loose body, or cartilage damage

Management: Usually benign if painless. If symptomatic: Address muscle tightness, improve hip control, modify aggravating activities.

Hip Impingement Patterns

Common restrictions:

• Limited internal rotation (most common)
• Restricted hip flexion with adduction and internal rotation (FADDIR test positive)
• Asymmetrical rotation patterns between hips

Considerations: May predispose to compensatory movement patterns at lumbar spine or knee. Address through targeted mobility and motor control training.

Related Joints

Lumbar Spine

Relationship: The hip and lumbar spine share movement responsibilities through the lumbopelvic rhythm. Limited hip mobility often results in excessive lumbar compensation.

Clinical Implications:

• Hip flexion restrictions increase lumbar flexion demands (deadlifts, squats)
• Tight hip flexors contribute to anterior pelvic tilt and lumbar extension
• Hip extension deficits increase lumbar hyperextension during gait

Training Considerations: Assess and address both regions. Improve hip mobility to reduce lumbar stress. Strengthen hip extensors to support neutral pelvic position.

Knee

Relationship: Hip position and control directly influence knee alignment and loading through the kinetic chain.

Clinical Implications:

• Weak hip abductors allow pelvic drop and dynamic knee valgus
• Limited hip internal rotation may increase tibial internal rotation
• Hip extension deficits increase knee extension demands during gait

Training Considerations: Hip strengthening (particularly glute medius) is essential for knee injury prevention. Address hip mobility restrictions that alter knee mechanics.

Ankle

Relationship: Hip and ankle work synergistically during stance phase. Restrictions at one joint increase demands on the other.

Clinical Implications:

• Limited ankle dorsiflexion increases hip flexion requirements in squatting
• Hip external rotation compensations may occur with ankle mobility deficits

Sources

• Neumann, D.A. (2017). Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation (3rd ed.). Elsevier.
• Kapandji, I.A. (2019). The Physiology of the Joints, Volume 2: Lower Limb (7th ed.). Handspring Publishing.
• Reiman, M.P., & Thorborg, K. (2014). Clinical examination and physical assessment of hip joint-related pain in athletes. International Journal of Sports Physical Therapy, 9(6), 737-755.
• Lewis, C.L., & Sahrmann, S.A. (2015). Effect of posture on hip angles and moments during gait. Manual Therapy, 20(1), 176-182.
• Griffin, D.R., et al. (2016). Hip arthroscopy versus best conservative care for the treatment of femoroacetabular impingement syndrome (UK FASHIoN): a multicentre randomised controlled trial. The Lancet, 391(10136), 2225-2235.