This document discusses biomechanics of the spine and hip, including movements, forces, positioning, and injuries. It covers spinal deviations like lordosis and kyphosis. Forces on the spine include body weight, ligament and muscle tension, and intra-abdominal pressure. Maintaining an upright position requires counteracting torque with back extensor muscle tension. Lifting techniques should use the legs to reduce torque on the back. Common back injuries include pain, fractures, and disc herniations. Prevention focuses on proper posture, lifting, and strengthening weak muscles.

1. Biomechanics of the Spine & Hip
• Movements of Spine
– Flexion, Rotation, Extension, Abd, Add.
• Hip Movements
– Elevation, Anterior & Posterior Tilt, Flexion,
Extension, Abd, Add, Hyperext, Hyperflex

2. Spinal Deviations
• Lordosis
• Kyphosis
• Scoliosis

3. Forces Acting On The Spine
• Forces Acting On The Spine Include:
– Body Weight
– Tension In The Spinal Ligaments
– Tension In The Surrounding Muscles
– Intraabdominal Pressure
• The Major Form Of Loading On The Spine Is:
– Axial

4. Upright Position
• Spinal Compression
– Resulting From:
– Body Weight + Weight Held
by Arms and Hands
• When Standing Upright
– Total Body Center of Gravity
Is Anterior to the Spinal
Column.
– Spine Is Placed Under
Constant Forward Bending
Moment.

5. Torque
• Defined: The Rotary Effect of a Force
About An Axis of Rotation, Measured as the
Producer of the Force and the Perpendicular
Distance Between the Force’s Line of
Action And The Axis
• To Maintain An Upright Position
– Torque Is Counteracted by Tension in the Back
Extensor Muscles.

6. Spinal Muscles Role In Lifting
• Spinal Muscles Have
Small Moment Arms With
Respect To the Vertebral
Joints.
• Have To Generate Large
Forces To Counteract the
Torque Produced About
the Spine by Body Weight
and Objects Being Lifted.
Erector Spinae
Muscles

7. Why Lift With The Legs?
• Back Muscles, With a
Moment Arm of
Approximately 6 cm,
Must Counter The
Torque Produced by
the Weights of the
Body Plus Any
External Loads.

8. Question: How Much Torque Is Developed By
The Erector Spinae Muscles With a Fm 6 cm?
• 1 lb. = 4.448 Newtons
• Segment Weight Moment Arm
– Head 13 lbs. (58N) 25 cm
– Trunk 73.75 lbs.(328N) 10 cm
– Arms 18.2 lbs. (81N) 20 cm
– Box 24.95 lbs.(111N) 40 cm
• Torque at L5-S1=
• (328N)(10cm) + (81N)(20cm) + (58N)(25cm)
+ (111N)(40cm)
• = ?
• 10,790 Ncm
• Force?
• 0 = (Fm)(6cm) - 10,790 In static position, sum
• of the torques acting at any point is zero.
• Fm = 1798.33 N or (404.30 lbs.)

9. Problem for a 135 lb. Person
• How much force must be developed by the erector
spinae with a moment arm of 6 cm. From the L5-
S1 joint center to maintain the body in a lifting
position with segment moment arms as Specified?
• Segment Weight Moment Arm
– Head 50 N 22 cm.
– Trunk 280 N 12 cm.
– Arms 65 N 25 cm.
– Box Lifted 100 N 42 cm.
• Torque ?
• 10,285 Ncm
• Fm = 1714 N or (393 lbs. Force)

10. What Does The Research Show?
• % Load Compression On L3 During the Upright Standing, Lying Down,
and Sitting.
• Compression Increases More with Spinal Flexion, and Increases Still
Further with a Slouched Sitting Position.

11. Common Injuries Of The Back
– Low Back Pain
– Soft Tissue Injuries
– Acute Fractures
– Stress Fractures
– Disc Hernia ions
– Whiplash Injuries

12. Low Back Pain
75%-80% of Americans Experience Low
Back Pain Sometime During Life.
Second Only to the Common Cold In Causing
Absence In The Workplace.
Mechanical Stress & Psychosocial.

13. BACK, SPINAL COLLUMN,
NECK
•VERTEBRAL
COLLUMN
•RIBS & STERNUM

14. SPINAL COLLUMN
• 7 CERVICAL
VERTEBRAE
• 12 THORACIC
• 5 LUMBAR
• 1 SACRUM - FUSED
• 1 COXCYC - 2 FUSED

15. JOINTS OF THE VERTEBRAL
COLLUMN
•VERTEBRAL JOINTS
–GLIDING JOINTS -
SLIGHTLY MOVABLE
•SEPARATED BY
INTERVERTEBRAL DISKS

16. THORACIC COMPLEX - RIBS
• 12 SETS OF RIBS
• ARTICULATE WITH THE THORACIC
VERTEBRAE AND STERNUM
• 7 PAIRS OF TRUE RIBS - ATTACH
DIRECTLY TO STERNUM
• 5 PAIRS OF FALSE RIBS
–2 PAIRS OF FLOATING RIBS
–3 PAIRS ATTACH TO STERNUM VIA
COSTOCHONDRAL CARTLILAGE

17. STERNUM
•MANUBRIUM
•BODY
•XIPHOID PROCESS

18. MUSCLES OF THE BACK,
NECK & ABDOMEN
•DEEP POSTERIORS
•ABDOMINALS
•VERTEBRALS
•SUPERFICIAL NECK
MUSCLES

19. DEEP POSTERIORS
• MOVEMENT - ROTATION,
EXTENSION OF SPINAL
COLLUMN

20. ABDOMINALS
• TRANSVERSE ABDOMINUS
- DEPRESSION OF
ABDOMEN
• RECTUS ABDOMINUS -
SPINAL FEXION
• INTERNAL / EXTERNAL
OBLIQUES - ROTATION,
LATERAL FLEXION
(ABDUCTION -
ADDUCTION)

21. MUSCLES OF THE THORAX
• DIAPHRAM
• INTERNAL INTERCOSTALS
• EXTERNAL INTERCOSTALS

22. INJURIES TO LOWER SPINE,
PELVIS, HIP - CAUSES
• DISK DEGENERATION - Herniation or General
Degeneration
• JOINT DISFUNCTION - Primarily @ Sacroiliac
– Usual Cause - Lack of Normal Movement - Often Disputed
• STRETCHED OR STRAINED LIGAMENTS - ie:
Supraspinous Ligaments
• LACK OF STRENGTH
– Hamstrings, Erector Spinae, Abdominals, Hip Flexors

23. PREVENTION OF INJURIES
TO BACK
• POSTURE - STANDING
– HYPERLORDOSIS
– KYPHOSIS
• POSTURE - SITTING
– CAUSING PAIN TO LUMBO/SACRAL AREA

24. PROPER SITTING TECHNIQUE -
Should Not Be Done Over Long
Periods Of Time
• HIPS SHOULD BE FLEXED
• LEGS SHOULD NOT BE EXTENDED
• BACK SHOULD NOT BE OVERLY ARCHED

25. LIFTING WITH PROPER
TECHNIQUE
• BACK KEPT ERECT
• KNEES BENT
• WEIGHT CLOSE TO BODY

26. STRENGTHENING
EXERCISES
• MANY BACK PROBLEMS ARE CAUSED BY WEAK MUSCLES ABOUT THE
HIP AND ABDOMINALS
• WEAK MUSCLES PREDISPOSE BACK TO HYPERLORDOSIS
• INCORRECT SIT-UPS MAY CAUSE HYPERLORDOSIS - CAUSED BY
SHORTENED ILIOPSOAS
• STRETCHING - HAMSTRINGS - ILIOPSOAS - QUADRICEPS

27. LUMBAR SPINE
EVALUATIONS
• STANDING EVALUATION
• FLEX FORWARD -
PALPATING SPINOUS
PROCESSES &
TRANVERSE PROCESSES
• SITTING ALIGNMENT
• PATELLULAR REFLEX -
LUMBAR 4
INVOLVEMENT
• ACHILLES REFLEX -
SACRAL 1
INVOLVEMENT

28. LYING ON BACK
• TEST ABDOMINALS - RECTUS
ABDOMINUS , ILIOPSOAS (HIP
FLEXORS)
–(STATIC W/ STABILIZED THIGHS - HIP
FLEX AT 45 DEGREES
• STRAIGHT LEG RAISE
–PAIN WHEN TESTING UNAFFECTED SIDE
- POSSIBLE HERNIATED DISK
–PAIN WHEN TESTING AFFECTED SIDE -
POSSIBLE SCIATIC NERVE STRETCHED

29. LYING ON BACK
(CONTINUED)
• BOWSTRING SIGN
–TO TEST FOR SCIATIC NERVE -
USE PRESSURE TO POPLITEAL
(BACK OF KNEE)
• GAINSLENS SIGN
–TO TEST SACRO-ILIAC
LESSIONS (SWITCHBLADE
LEGS WHILE ON SIDE)

30. OTHER PROBLEMS
OCCURING WITH THE SPINE
• SOFT TISSUE TRAUMA - CONTUSIONS
• NERVE INFLAMATION OR COMPRESSIONS - FROM DISK
PROTRUSIONS
• FRACTURES TO THE SPINOUS OR TRANSVERSE PROCESSES
• SPONDYLOLYSIS (FRACTURE TO INTERARTICULAR PROCESS
• SPONDYLOLISTHESIS (FORWARD SLIPPAGE OF THE VERTEBRA

31. OTHER PROBLEMS
OCCURING WITH THE SPINE
(CONTINUED)
• GROIN STRAINS
• HIP POINTE.RS
• HIP DISLOCATIONS

32. REHABILITATION OF BACK
AND HIP INJURY
• ICE MESSAGE
• MOVEMENT TO REGAIN FLEXIBILITY &
RANGE
• STRENGTHENING EXERCISES
– SIT UPS & CRUNCHES (WORK OBLIQUES AS WELL)
– PELVIC TILTS - (FLATTENING OF BACK AGAINST
FLOOR)
– HIP LIFTS - (FROM LYING ON BACK POSITION)
– BACK EXTENTIONS - TO 90 DEGREES
– PSOAS & HAMSTRING STRETCH - (KNEES TO CHEST)