Lumbar Spine and Pelvis

Question 1

Observe muscles surrounding lumbar spine (longissimus, iliocostalis, and multifidus).

Which muscle is most developed in the lower lumbar region?

How do these muscles contribute to stability in the lumbar spine?

Answer 1

• Multifidus is the most developed in the LOWER lumbar region. Smaller moment arm = primary stabilizer of L/S
• Muscles provide stability and mobility to the L/S. Because of the difference in moment arm, multifidus (smaller moment arm) is throught to be the primary stabilizer of the L/S, while the Erector Spinae (larger moment arm) are thought to be the primary movers of the spine.
  
  • Due to different attachment sites, these mm will contribute to different movements.

Question 2

Yo (160 cm, 60 N) is picking up a pen off the ground by bending her lumbar spine and hips. Estimate the force needed by the lumbar extensor mm to accomplish this task.

Answer 2

• The interal torque produced by the extensor mm must be equal and opposite to the torque produced by the external force. So, equation is (extensor mm force)*(moment arm of extensor) = (weight of upper trunk)*(moment arm upper trunk).
• Weight of upper trunk is about 50% total body weight (60N/2=30N) and to simplify example, we’ll assume that its mass is midway up the trunk. Since the length of the upper trunk is about 50% of total BH, lever arm of upper trunk will be 25% of BH (164/4 cm).
• Moment arm of back extensor is about 5 cm
• Equation is now: (external mm force)*(5 cm) = (60/2)*(164/4).
• Extensor mm force = 240 N.
• Large mm force needed is primarily due to small lever arm of the mm when compared to lever of external force.
  
  • Large mm force acting on spine will dramatically increase posteriro shear and compression forces on the spine and disc.

Question 3

Compare and contrast the “stoop” and “squat” lifting techniques.

Answer 3

• Stoop Lift
  
  • Pros: Less demand on knees
  • Cons: Creates large force possibly damaging compression and shear to discs
  • Long external moment arm (thus increased demand on lumbar extensors)
• Squat Lift
  
  • ​Pros: Reduced external moment arm of load/trunk (thus diminished extensor torque demands on lumbar extensors)
  • Cons: Creates greater demand on quadriceps to produce extensor torque; Large imposed force on tibiofemoral and patellofemoral joints

Question 4

Describe the AOR for sagittal, frontal, and transverse plane motion of the lumbar spine.

Answer 4

• Sagittal: ML axis - posterior portion of IV disc
• Frontal: AP axis - contralateral side of disc
• Transverse: Longitudional Axis - center of disc

Question 5

What are the attachments of the psoas and iliacus muscle?

Answer 5

• Psoas
  
  • Superficial layer: Lateral surfaces of T12 vertebral bodies, L1-L4 vertebral bodies and associated IV discs
    
    • –> Lesser Trochanter
  • Deep layer: transverse processes of L1-L5 vertebrae
    
    • —> Lesser trochanter
• Iliacus: Iliac crest, iliac fossa
  
  • —> Tendon of psoas and lesser trochanter

Question 6

Describe the line of pull (if any) of the psoas and iliacus on the lumbar spine

Answer 6

• Psoas: Anterior and inferior (pulling into anterior tilt -> extension/lordosis and inferior)
• Iliacus: no direct attachment to L/S and therefore no action at L/S

Question 7

Does shortening of the iliacus or psoas have an effect on posture of the lumbar spine?

Answer 7

• Yes, if these mm are shortened, there wil be an increased lumbar lordosis (increased extension) as well as increased anterior pelvic tilt and decreased hip extension)
• Psoas has an anterior-inferior pull on the L/S. With a stable pelvis, the psoas will technically flex the L/S; however, its attachments are both anterior and posterior to the AOR.
• Iliacus will cause anterior pelvic tilt, which will resut in an increased lordosis (extension) due to lumbopelvic rhythm.
• If help flexors are shortened, they will increase lordosis.

Question 8

What occurs at the different spinal levels when a PA motion to L3-L5/S1 is given?

Answer 8

• PA motion to the SP produces extension generally at that level and the levels above/below from L3-L5/S1.
• PA to L1 and L2, extension is observed at L1-L3/4, while relative flexion observed at L4/L5 and L5/S1 levels.

Question 9

What happens to L3/L4 and L4/L5 when a PA force is applied to SP of L3?

What happens to L2/L3 when a PA force is applied to SP of L3?

Answer 9

• When a PA force is applied to the SP of L3, the caudal facet of L3 approximate to cranial facets of L4 and impose motion on the L4 vertebra.
  
  • In addition to causing extension, force from L3 facets on L4 likely glides the L4 vertebra anteriorly, causing subsequent approximation at the L4/L5 segment via a similar mechanism to that at L3/L4.
• At L2-L3 segment, when a PA force applied to L3 SP, force will glide the superior facets of L3 away from inferior facets of L2, separating the L2-L3 facet joint surfaces.
  
  • This separation would cause the facet joint capsule to become taut, pulling the caudal facet of L2 vertebra anteriorly, causing it to extend in relation to L3.

Question 10

What happens to L1/L2, L2/L3 when a PA force is applied to L1 and L2 SP?

What happens to L4/L5 and L5/S1 when a PA force is applied to L1 and L2 SP?

Answer 10

• When a PA force is applied to L1 and L2 SP, force on L1 and L2 result in segmental extension at targeted segment and other upper two segments.
  
  • L2/L3 and L3/L4 for PA pressure at L1
  • L1/L2, and L3/L4 for PA pressure at L2
• Remaining caudal segments (L4/L5, L5/S1 were observed to flex.
  
  • Prevailing flexion response was most likely to related to fixed mass of pelvis (serving as a coutnerweight to PA force application at L1 and L2.

Question 11

General arthrokinematics for flexion at lumbar spine?

Answer 11

Inferior facets of superior segment glide superior and anterior on superior facets of inferior segment.

Question 12

General arthrokinematics for extension at lumbar spine?

Answer 12

Inferior facets of superior segment glide down and approximate the superior facets of the inferior segment.

Question 13

General arthrokinematics for rotation at lumbar spine?

Answer 13

• Ipsilateral facet gaps
• Contralateral facet approximated
  
  • Rotation: contralateral facet closes

Question 14

General arthrokinematics for sidebending at lumbar spine?

Answer 14

• Ipsilateral facets approximated/glide down
• Contralateral facets glide up/gap
  
  • Side bend: Ipsilateral facet closes

Question 15

Clinical Examples of Arthrokinematics:

1. If a patient forward bends and deviates to same side what side has suggested capsular tightness? Why?
2. If a patient is unable to rotate in one direction, which side is hypomobile and will not allow gapping?
3. If a patient is unable to extend, what does it suggest that the facets are unable to do?
4. In the extension position, if a patient can only side bend to the right with limited ROM, it may suggest that which facet is hypomobile?

Answer 15

1. If a patient forward bends and deviates to the same side, it suggests capsular tightness on side of deviation; facet is unable to fully glide superior/anterior and open
2. If a patient is unable to rotate in one direction, hypmobile facet joint on same sie, and will not allow gapping on that side (Rotation limited by ipsilateral hypmobile facet not allowing gapping)
3. If a patient is unable to extend, it suggests inability of facets to downglide.
4. In the extension position, if a patient can only side bend to the right with limited motion, it may suggest that the left facet is hypomobile (Sidebend limited by contralateral hypomobile facet not allowing gapping)

Question 16

In addition to facet joint arthrokinematics, the lumbar movement also affects what space? Give an example.

Answer 16

In addition to facet joint arthrokinematics, the lumbar movement also affects foraminal space.

• Ex. Extension and/or SB right decrease the right foraminal space
  
  • Flexion and SB left would increase the right foraminal space

Question 17

Panjabi. Regardless of the moment applied, there is a non-linear load-displacement curve. What anatomical aspects of the spine drive this relationship?

Even when little torque is applied, there is movement of the spine - why? How would this motion change with age? How would injury to the disc change this?

Answer 17

• IV discs are an important anatomical contributor to this relationship. Disc allows for high flexibility at low loads, but as the loads increase and the disc compresses further, less movement occurs at higher loads, thus blocking motion towards end range.
• Ligamentous support of spine also limits motion near end range.
• Even when little torque is applied, spine has some motion = NEUTRAL ZONE
  
  • ​With little applied torque, spine is able to “rotate”, at least 2˚.
• Instances of disc injury without arthrosis/OA, instability of disc increases the neutral zone.
• As OA/arthrosis develops* over time, flexilibity of the spine decreases as demonstrated by *reduction in the netural zone.
  
  • Decreased disc height* that can also result from aging, also can *reduce magnitude of the neutral zone.

Question 18

Explain how a balloon is analogous to a disc relative to end-range resistance.

Answer 18

Balloon as disc: end range = increased resistance

Question 19

Explain how sitting on a Swiss Ball versus a chair demonstrates the netural zone.

Answer 19

Neutral zone: oscillation of disc, as cushion between vertebral bodies.

Question 20

What are the coupled motions that result when a pure extension moment is applied? A pure flexion moment? Where is the reference point located and why is this important?

Answer 20

• When a pure extension moment is applied, extension and inferior (approximation of the posterior vertebral body) and posterior translations ensued.
• When a pure flexion moment is applied, combined motions of flexion and superior (tension) and anterior translations occurred.
  
  • Less than 1 mm of lateral translation and less than 1 degree of rotation along and around the other axes
• The reference point is located at the inferiormost point on the posterior wall of the vertebral body of the moving vertebrae.
  
  • If the reference was located anteriorly, inferior translation would be reported.

Question 21

What was Panjabi evaluating in his study? Describe the experimental set-up. Which of the two commonly used methods in the study of spinal mechanics did Panjabi use to evaluate the motion of the L/S?

Answer 21

• Panjabi evaluated the 3D combined motion of the lumbosaral spine* with the use of the *flexibility method (moment is applied at motion that results from motion is measured).
  
  • Stiffness method measures the amount of torque required to produce a particular movement
  • Use of flexbility method allowed Panjabi to observe automatic combined motion of spien that result when a specific moment is applied.
    
    • This combined motion is guided by structural aspects of the spine and while not investigated in this study, also dependent upon sagittal plane position of spine.
• Panjabi evaluated motions of 9 fresh-frozen lumbosacral spine specimens that were dissected of all nonligamentous soft tissue and mounted polyester resin casts
• Three non-linear markers placed on anterior aspect of each vertebral body to assess spinal motion.
• Pure moments applied to most cranial vertebrae; accomplished by loading the spine with equal and opposite forces (pure moment). A 100N compressive force was also applied.
• Neutral indicates anatomical position of lumbosacral spine; therefore slight extension (lordosis) of the spine.

Question 22

Interpret the coordinate system. Using the right-hand rule, right rotation (ride side bend) is positive or negative for each axis?

Answer 22

• Z: Anterior-Posterior Axis
  
  • Positive: Anterior = R Sidebend
• X: Medio-Lateral Axis
  
  • Positive: Left = Flexion
• Y: Superior-Inferior Axis
  
  • Positive: Superior = L Rotation
• Right hand rule:
  
  • Thumb = y axis
    
    • superior/inferior = rotation
  • Middle finger = x axis
    
    • medio-lateral = flexion/extension
  • Pointer finger = z axis
    
    • anterio-posterior = sidebend
• Right Rotation about AP axis = Positive = Right Sidebend
  
  • ML axis positive = flexion
  • SI axis positive = L rotation

Question 23

Are there any differences in the amount of flexion and extension across the FSUs? Why or why not?

Across all FUs, there is more flexion than extension - why?

Answer 23

• There is greater flexion at L4/L5 and L5/S1 than L1/L2 and L2/L3. This will likely result from facet orientation, FSU location in space (more natural extension at L4/L5 and L5/S1, so more room to go into flexion), and possibly capsular differences.
• There is greater extension at L5/S1 as compared to all other FSUs. This likely results from facet orientation (promoting sagittal motion) and the lack of a prominent spinuous process of S1 (limits bony abutment).
• When comparing flexion versus extension, for a given torque, extension is limited by the boney approximation of the facets and the spinuous process.

Question 24

Describe the coupled motions that result when a pure side moment is applied.

What anatomical factors could contribute to this observed coupled movement pattern? What happens when you go into R SB?

Answer 24

• A pure side moment results in flexion and contralateral rotation of the spine. There is also lateral translation in the direction of the side bend.
  
  • Ex. With a right side bend moment, the FSU flexes, translates to the right, and rotates left.
  • Ex. With a left side bend moment, the FSU flexes, translates to the left, and rotates right.
  • In both instances, superior translates also result but are small (<1mm).
  • Coupled axial rotation was found to be greatest at L4/L5 and L5/S1.
    
    • Likely due to differences in facet orientation.
• If we examine the facet of the L/S closely, the inferior facet has a U-shape. As you go into R side bend, inferior articular process approximates with this area of the facet joint (circle); this can push the process to the right, thus resulting in left rotation.
  
  • You can see a side bend is coupled with contralateral rotation in an extended spine.

Question 25

Topography Skill: Locate SP in prone.

Perform a Prone PA. What can this technique be used for?

Why is the L5 SP difficult to palpate?

Answer 25

Prone PA accessory motion can be used for assessing lumbar hypomobility and/or symptom reproduction.

L5 SP is difficult to palpate beacuse it is short in both the cranial-cadual direction and anterior-posteiror direction.

Question 26

Topography skill: Assess Sidelying L/S Segmental Motion.

What can this technique be used for? Should patient be symptomatic with this? Describe patient and PT position.

Answer 26

• Sidelying L/S Segmental Motion used to assess segmental hypermobility.
• Patient should not be symptomatic with this technique.
• Pt. positioned close to therapist with spine in neutral. Pt.’s knees flexed to maximum position before L/S moves out of neutral position.
• PT caudal forearm used to keep patient’s knees locked into therapist’s hip. Stabilize pt ubber body using ulnar side of palpating hand.
• Mobilize spinal segments from cadual to cranial by imparting AP movement through patient’s femurs by weight shift.

Question 27

Topography skill: Prone mobilization.

Describe patient position and procedure.

What does this technique allow for?

Answer 27

*Described below for R rotation of cranial segments and relative L rotation of cadual on cranial segment - this is a treatment.

• Patient prone with head turned to left. Extend pt’s lumbar spine by raising cranial end of table.
• Sidebend patients spine to L passively. Palpate L side of segment you wish to mobilize and one segment below. Once segment has moved into side bending, stop moving.
• PT use hypothenar eminence to stabilize TP on R side of segment below one you wish to mobilize. Apply a PA force to TP in order to stabilize this segment.
• Have pt turn head to R and place R hand near head. Ask pt. to press up with R hand to impart R rotation to segments above one PT is stabilizing; relative left rotation of segment being stabilized on segment above.
• **Should be minimal to no activation of pts L/S paraspinals!!!
• Allows PT to impart a mobilization from cranial to caudal while maintaining more caudal segments in neutral.
  
  • Can be performed passively or as a mobilization with movement.