Checklist for Identifying Clinical Instability in the Lumbar Spine

 

Parameters:

(1) status of anterior elements

(2) status of posterior elements

(3) radiographic criteria on flexion/extension or resting X-rays of the spine

(4) status of cauda equina

(5) anticipated loading

Parameter	Finding	Points
anterior elements	destroyed or unable to function	2
	not destroyed and able to function	0
posterior elements	destroyed or unable to function	2
	not destroyed and able to function	0
cauda equina	damage present	3
	damage absent	0
anticipated loading	dangerous	1
	not dangerous	0

 

 

X-ray Type	Measure	Finding	Points
flexion/extension	sagittal plane translation	> 4.5 mm OR > 15%	2
		<= 4.5 mm AND <= 15%	0
	sagittal plane rotation	L1-L2 > 15° L2-L3 > 15° L3-L4 > 15° L4-L5 > 20° L5-S1 > 25°	2
		L1-L2 <= 15° L2-L3 <= 15° L3-L4 <= 15° L4-L5 <= 20° L5-S1 <= 25°	0
resting	sagittal plane displacement	> 4.5 mm OR > 15%	2
		<= 4.5 mm AND <= 15%	0
	relative sagittal plane angulation	> 22°	2
		<= 22°	0

 

where:

• Either the flexion/extension or resting X-rays finding are used, probably whichever is greater.

• The maximum points for radiographic criteria is 4.

 

Measurement of vertebral translation or displacement in a lateral X-ray view:

(1) This is shown in Figure 5-61 on page 354.

(2) A straight line is taken along the superior surface of the vertebra in question.

(3) A vertical line is drawn perpendicular to the straight line that goes through the posterior inferior aspect of the vertebra immediately above.

(4) distance B = width through the vertebral body immediately above in its vertical midpoint

(5) distance A = measurement from the point of intersection between the straight and vertical line along the straight line to the posterior superior aspect of the vertebra in question

(6) Abnormal if A > 4.5 mm OR A/B > 0.15

 

Measurement of sagittal plane rotation in a lateral X-ray view:

(1) This is shown in Figure 5-63 on page 355.

(2) Angle A = angle formed anteriorly by the meeting of a straight line through the superior aspect of the body of the first vertebra and a straight line through the superior aspect of the body of the second vertebra when the spine is flexed anteriorly.

(3) Angle B = angle formed posteriorly by the meeting of a straight line through the superior aspect of the body of the first vertebra and a straight line through the superior aspect of the body of the second vertebra when the spine is extended posteriorly.

(4) By convention lordosis is indicated by a negative value and kyphosis is indicated by a positive value. In the example given angle B is a negative number.

(5) sagittal plane rotation = A - B

 

Measurement of relative sagittal plane angulation in a lateral X-ray view:

(1) This is shown in Figure 5-62 on page 355.

(2) Angle B1 = angle formed posteriorly by the meeting of a straight line through the superior aspect of the body of the vertebra 2 above the spinal unit in question (L2 for L4-L5 unit) and a straight line through the superior aspect of the body of the vertebra 1 above the unit (L3 for L4-L5).

(3) Angle B2 = angle formed anteriorly by the meeting of a straight line through the superior aspect of the body of the vertebra 1 above the spinal unit in question (L3 for L4-L5 unit) and a straight line through the superior aspect of the first vertebral body of the unit (L4 for L4-L5).

(4) Angle B3 = angle formed posteriorly by the meeting of a straight line through the superior aspect of the first vertebral body of the unit (L4 for L4-L5) and a straight line through the superior aspect of the body of the second vertebral of the unit (L5 for L4-L5).

(5) By convention lordosis is indicated by a negative value and kyphosis is indicated by a positive value. In the example given angles B1 and B3 were negative values.

(6) If either B2 – B1 or B2 – B3 is > 22°, then the angulation is abnormal.

 

score =

= SUM(points for all the parameters)

 

Interpretation:

• minimum score: 0

• maximum score: 12

• A score >= 5 indicates that the lumbar spine is clinically unstable.