The document discusses the pathology, clinical presentation, diagnosis, and management of ossification of the posterior longitudinal ligament (OPLL). It covers the epidemiology, genetics, radiological features, and various surgical approaches for treating OPLL, including anterior corpectomy with fusion and posterior laminectomy with or without fusion. Anterior decompression is preferred for large occupying lesions or kyphosis, while posterior laminoplasty is an option for smaller lesions with a preserved lordosis. The goal of surgery is decompression with stabilization to prevent postoperative progression of OPLL.

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