This presentation is aimed for educational purpose for medical staff

1. OPLL
Mohamed Wael Samir, MD
Prof. of Neurosurgery
Ain Shams University
Cairo, Egypt

2. ILOs
 Pathology of OPLL
 Clinical presentation
 Diagnosis of OPLL
 Management of OPLL

4. Pathology
 1) Cell of origin & pathogenesis
 2) Epidemiology
 3) Macroscopic features
 4) Microscopic features
 5) Immunohistochemistry
 6) Genetic features
 7) Radiological features
 8) Growth pattern & spread
 9) Grading & behavior
 10) Prognosis

5. Pathogenesis
 ligament cells from patients with OPLL have osteoblast-like
characteristics
Factors that intiate these cells to form calcification & ossification are:
 Genetic factors: Genetic locus for OPLL is thought to be located close to
the HLA region, on chromosome 6p
 Hormonal factors: non–insulin dependent D.M., hypoparathyroidism and
hypophosphatemic
 Environmental factors: Mechanical stress in ligaments of the spine
 Life style

6. Pathogenesis Of Neural Injury In OPLL
 A) Mechanical:
 1) Static compression:
 Occupying ratio greater than 60% indicates high risk of the
development of myelopathy
 SAC < 6 mm
 2) Dynamic compression:
 Degenerative spondylolithesis
 Threshold of SAC
 Normal= 13mm
Myelopathy
 with SAC < 6 mm = Static compression
 Myelopathy with SAC 6-13 = Dynamic
 B) Vascular:

7. Pathology
 1) Cell of origin & pathogenesis
 2) Epidemiology
 3) Macroscopic features
 4) Microscopic features
 5) Immunohistochemistry
 6) Genetic features
 7) Radiological features
 8) Growth pattern & spread
 9) Grading & behavior
 10) Prognosis

8. Epidemiology
 Incidence:
 In Japanese >30 ys up to 4%.
 In the United States and Europe, up to 1.7%.
 Gender:
 Cervical: Male > Female (2 : 1)
 Dorsal: Female > Male
 Race:
 More in Japanese
 Age:
 Started in 40s and became symptomatic in 50s
 Risk factors:
 Genetic: genetic locus for OPLL is thought to be located close to the HLA
region, on chromosome 6p
 DM

9. Pathology
 1) Cell of origin & pathogenesis
 2) Epidemiology
 3) Macroscopic features
 4) Microscopic features
 5) Immunohistochemistry
 6) Genetic features
 7) Radiological features
 8) Growth pattern & spread
 9) Grading & behavior
 10) Prognosis

10. Pathology
 Site:
 Cervical (C2-C4): 70%,
 Dorsal (T1-T4): 15%
 Lumbar (L1-L3):15%
 There is high frequency with which cervical OPLL is associated with
thoracolumbar OPLL and OLF
 Character:
 Early: PLL hypertrophy
 Then: Punctate calcification within PLL
 Then: Actual ossification


11. Four Classical Types Of OPLL
Circumscribed
 1) Segmental type (39%),
 2) Mixed type (29%),
 3) Continuous type (27%),
 4) Circumscribed type (5%)

12. Types Of OPLL

Hill-type Square-type mushroom-type
Continuous type circumscribed type
segmental type
Continuous type
Mixed type

13. Pathology
 1) Cell of origin & pathogenesis
 2) Epidemiology
 3) Macroscopic features
 4) Microscopic features
 5) Immunohistochemistry
 6) Genetic features
 7) Radiological features
 8) Growth pattern & spread
 9) Grading & behavior
 10) Prognosis

14. Microscopic Features
 Early OPLL:
 Hypertrophy PLL due to fibroblastic hyperplasia and increased collagen
deposition with accompanying punctate ossification centers
 Immature form:
 Woven bone with fibrocartilaginous cell proliferation
 Mature form:
 Lamellar bone with well-developed haversian systems
 Mostly endochondral ossification & sometimes membranous

15. Microscopic Features Of Pathological Changes Of Cord
 Demyelination and loss of axon always found in the posterior and
posterolateral part of the cord (so posterior decompression may insult
the cord whis is alredy insulted posteriorly)

16. Pathology
 1) Cell of origin & pathogenesis
 2) Epidemiology
 3) Macroscopic features
 4) Microscopic features
 5) Immunohistochemistry
 6) Genetic features
 7) Radiological features
 8) Growth pattern & spread
 9) Grading & behavior
 10) Prognosis

17. Genetic Features
 A genetic locus near the human leukocyte antigen site (HLA) on
chromosome 6p
 Ossification of post. Longitudinal ligament (OPLL)
 Ossification of ligamentum flavum (OLF)
 Ossification of ant. Longitudinal ligament (OALL)
 Diffuse idiopathic skeletal hyperostosis (DISH)

18. Pathology
 1) Cell of origin & pathogenesis
 2) Epidemiology
 3) Macroscopic features
 4) Microscopic features
 5) Immunohistochemistry
 6) Genetic features
 7) Radiological features
 8) Growth pattern & spread
 9) Grading & behavior
 10) Prognosis

19. Types Of OPLL

Hill-type Square-type mushroom-type
Continuous type circumscribed type
segmental type
Continuous type
Mixed type

20. Dural Calcification

21. Pathology
 1) Cell of origin & pathogenesis
 2) Epidemiology
 3) Macroscopic features
 4) Microscopic features
 5) Immunohistochemistry
 6) Genetic features
 7) Radiological features
 8) Growth pattern & spread
 9) Grading & behavior
 10) Prognosis

22. Natural History Of OPLL
 OPLL ↑ in thickness 0.4mm/y & in longitudinal expansion 0.67mm/y
 It is more with continuous- or mixed-type OPLL
 A rapid progression in the 4th decade then gradually decreases in the
5th or 6th decade.
 It occurs also postoperative
 In 60- 70 % after posterior decompression
 In 36-64 % after anterior decompression and fusion
Do These mean prophylactic surgery is
indicated?

23. Postoperative Progression Of The Ossified Lesion

24. Causes Of Late Deterioration
 Postoperative progression of OPLL,
 Progressive deformity and instability
 Thoracic myelopathy secondary to OPLL or OLF or both,
 Degenerative lumbar stenosis,

25. Pathology
 1) Cell of origin & pathogenesis
 2) Epidemiology
 3) Macroscopic features
 4) Microscopic features
 5) Immunohistochemistry
 6) Genetic features
 7) Radiological features
 8) Growth pattern & spread
 9) Grading & behavior
 10) Prognosis

26. Prognosis
 Patient’s factors:
 Old age
 Preoperative neurological stat & duration of symptoms
 History of trauma causing acute presentation
 Disease’s factors:
 Occupying ratio of OPLL or SAC
 Sagittal shape of ossification (hill-shaped) especially with posterior
decompression
 Management’s factors:
 Progression may be more with posterior decompression

28. Clinical Picture
 Accidental discovery
 Onset: Usually gradual progressive but may be acute (after trauma)
 Pain:
 Axial pain
 Radicular
 Neurological deficits:
 Myelopathy or myeloradiculopathy rather than radiculopathy alone
 Associated coexisting conditions:
 Diabetic
 Hypoparathyroidism,
 Myotonic muscular dystrophy

29. Myelopathy Scales: Nurick Scale

30. The Modified Japanese Orthopaedic Association (mJOA) Scale
 Normal: 18
 Mild myelopathy: 15-17
 Moderate myelopathy: 12-14
 Severe myelopathy: ≤ 11

32. Plain Radiography
 Based on lateral 6-foot
plain x-rays, the normal
anteroposterior (AP)
dimension of the cervical
spinal canal should
measure 17 mm from C3-
7. Absolute stenosis was
defined as a canal
measuring 10 m or less,
whereas relative stenosis
was defined by a canal of
10 to 13 mm

33. Types Of OPLL
Continuous type
Plateau-shaped
Circumscribed type
hill-shaped

34. CT
 Thin axial
 Reconstructed 2D- and 3D-CT,
 Myelo-CT scans

35. CT In Early OPLL

36. CT

Hill-type Square-type mushroom-type
Continuous type Circumscribed type
segmental type
Continuous type
Mixed type

37. Dural Calcification

38. CT Signs of Dural Penetrance (Single-layer & Double-layer
Signs)
Double-layerSingle-layer (large
central mass with
unilateral “C” signs)
Single-layer (large
central mass with
bilateral “C” signs)

39. How Much Corpectomy?

40. 3D-CT

41. CT Dorsal Spine

42. Radiological Signs Help In Choosing Approach
 Occupying ratio:
 > 40% indicates high risk of the development of
myelopathy
 > 40% carry more risk in posterior decompression
especially with hill-shaped ossification
 Space available for the cord (SAC):
 Normal ≥ 13 mm
 Relative cervical stenosis: 10-13 mm
 Absolute stenosis: < 10 mm
 K line:
A line drawn from the middle of the spinal canal at
the C2 and C7 levels

43. K line

44. Documentation Of Fusion

45. Investigations: MRI
 High incidence of associated disc herniation in
patients with cervical OPLL
 Differentiation between multiple discs & early
OPLL by the contrast enhancement in OPLL and
extension behind bodies.
 Pathological changes in spinal cord

47. Treatment
 Conservative management:
 Surgical management:

48. Conservative Management
 Indications:
 Axial pain without or with subclinical myelopathy (e.g. only extensor
planter)
 Main insult is dynamic compression (less than 60% stenosis or 6-13 mm
SAC
 Sever comorbidity
 Measures:
 Collar
 Traction
 Carful life stile

49. Surgery: Indications
Is there a rule for prophylactic surgery?
 Myelopathy or radiculo-myelopathy with predominant myelopathy
 Role of prophylactic surgery in asymptomatic patient
 Sever canal compromise:
 SAC less than 6mm or
 Occupational ratio more than 60%
 Presence of cord signal in MRI
 SSEP is affected
 Young age (less than 65ys)


50. Surgical Procedures
Anterior surgery: Single/multilevel (up to 4)
 Corpectomy with removal of calcified mass
 Corpectomy without removal of calcified mass (ant. floating method)
 Open Window Corpectomy (removal of post1/2 of body leaving the ant.
One)
 Oblique Cervical Corpectomy
 With fusion & halo vest or with fusion and fixation
 Posterior surgery:
 Laminectomy
 Laminectomy + fixation & fusion
 Laminoplasty (open-door or double-door laminoplasty)
 Combined anterior-posterior surgery:

51. Choice Of Approach
 Factors in favor of ant. approach:
 Presence of facilities & expertise
 Occupying ratio more than 60%
 Hill-shaped calcification
 Kyphotic deformity or degenerative instability
 Limited corpectomy levels (up to 4)
 Factors allow post. approach:
 Comorbidity prevent more lengthy procedures
 Occupying ratio less than 60%
 Plateau-shaped calcification
 Preserved lordotic spine or maximum straightening

52. Anesthesia & Monitoring
 Awake fiberoptic intubation/positioning
 Intraoperative neural monitoring
 Motor evoked potentials,
 Somatosensory Evoked Potentials (SEPs),
 Electromyography


54. Posterior Approaches
 Laminectomy:
 Laminectomy + fixation & fusion
 Laminoplasty (open-door or double-door laminoplasty)

55. Laminectomy
 Advantages:
 Simple procedure
 Effective in selected cases
 Disadvantages:
 Post laminectomy scar formation may
compress cord
 ↑ incidence of kyphosis & instability
 ↑ incidence of POLL progression
 Procedure:
 C3-C7 (possibility of OPLL progression)
 + < 25% of medial facetectomy (for root
decompression)

56. Laminectomy & Fusion
 Advantages:
 ↓ risk of postoperative kyphotic deformity & spinal instability
 Disadvantages:
 Potential risk of vertebral artery or neural injury
 More lengthy procedure
 Procedures:
 Cables can be used in sublaminar, interspinous, or facet wiring techniques
 Screws & rods/plate construct fixation can be uses with lateral mass
plating or pedicular screw fixation

57. Expansive Laminoplasty
 Advantages:
 Simple with relatively with low
complication rate
 Less risk of kyphosis deformity &
instability
 Less risk of scar tissue formation
compressing cord
 Disadvantages:
 Risk of OPLL progression
 Limited effectiveness in severe kyphotic
deformity or large OPLL
 Procedures:


59. Ant. Approach
 Corpectomy with removal of calcified mass
 Corpectomy without removal of calcified mass (ant. floating method)
 Open Window Corpectomy (removal of post. ½ of body leaving the
ant. One)
 Oblique Cervical Corpectomy
+
 Fusion & halo vest (for 6-8 weeks) or
 Internal fixation & fusion

60. Corpectomy & Removal Of Calcified Mass
 Soft tissue dissection & discoidectomy as in ACDF
 Corpectomy width
 From preoperaztive CT < interpedicular distance
 The distance between the base of uncovertebral joint
 average 20- 25 mm
 3 layers of bone: cortical (ant. Vertebral surface) → cancellous
(vertebral body itself) → cortical (post. Vertebral surface & OPLL)
 Don’t separate the 3rd layer from lateral gutter till it is thinned out
 Separating the 3rd layer completely (sup./inf. & from both sides)
leaving the OPLL floating
 Tray to dissect the mass from dura
 Dural tear and CSF leak are the major drawback.

61. The Anterior Floating Method
 More extensive lateral exposure (>25 mm) to facilitate anterior
migration of the OPLL mass

62. Open Window Corpectomy

63. Oblique Cervical Corpectomy

64. Fixation By Halo Vest
 6-8 weeks

65. Fixation By Plating System
 Dynamic plates much more better than fixed plate in bone fusion

67. OPLL & OLF (Ossification of the Ligamentum
Flavum) of the Thoracic Spine
 They may be combined in upper thoracic region
 In mid & lower thoracic region OLF is more common
 OPLL at thoracic levels is more frequent in women than in men
 OLF treated by posterior decompression
 For upper dorsal (T1-4) OPLL: laminoplasty can be used safely
 For mid. & lower dorsal OPLLL: Laminectomy followed by
instrumentation is recommended