OPLL: Ossification of the Posterior Longitudinal Ligament

OPLL: Ossification of the Posterior Longitudinal Ligament


Preface

Ossification of the posterior longitudinal ligament (OPLL) is a disease that produces a chronic progressive compressive
myeloradiculopathy primarily in the cervical spine. The clinical manifestations of cervical OPLL often resemble
cervical spondylotic myelopathy (CSM), but OPLL exhibits unique epidemiological features, such as ethnic groups, age,
and gender preponderances. Furthermore, OPLL and CSM are very different in viewpoints of pathophysiology, surgical
management, and treatment outcomes.

Countless studies on OPLL have been published since its first description in the mid-nineteenth century. However,
little about this unique and famous disease has been known. This fact becomes obvious when considering the absence of
any clear-cut guidelines for the proper management or any classification system that is related to clinical outcomes of
OPLL. These ambiguities regarding OPLL are partly due to our ignorance on the disease itself. The etiology,
pathogenesis, and natural history of OPLL are not clearly known.

Japanese researchers have contributed extensively to our understanding of OPLL as it is, and most of the published
articles have dealt with the Japanese population. Therefore, people may regard OPLL as a Japanese disease. However,
OPLL is not limited to the Japanese population, and it
is equally prevalent in Korea, China, and other Asian countries. Furthermore, non-Asian reports are readily available
nowadays.

Major textbooks on spine surgery have chapters discussing OPLL, and Japanese researchers have published several
monographs on the topic of OPLL. However, given the recent surge of interest in OPLL in Korea, we Korean researchers
are obliged to summarize and update recent advancements in our knowledge of OPLL. This monograph is the first one
directed and presented by Korean researchers, with contributions from China and Japan. The most valuable contribution
of this monograph is the inclusion of recent Asian epidemiological studies that are not limited to Japanese results but
include Chinese and Korean data. In this monograph, we emphasize the clinical and surgical aspects of OPLL, rather than
basic science. Readers will thoroughly enjoy the presented information and discussions on the natural history, novel
surgical approaches and techniques, thoracic OPLL, and the relationship to other enthesopathies. I hope that this
textbook provides a basis for future research in OPLL in Asian and non-Asian countries.

The chapters in this monograph are based on a symposium to celebrate the retirement of Professor Hyun Jib Kim, the
fifth chairman of the Department of Neurosurgery, Seoul National University College of Medicine. Professor Kim was a
great mentor and a pioneer of spine surgery in Korea. He has been a dedicated spine surgeon since 1973, and he
introduced and developed techniques in spine surgery to educate his colleagues and disciples. Surgery for OPLL was one
of Professor Kim’s achievements, and the symposium was directed to focus on OPLL. Authors from many Asian countries
were included to obtain a wide and balanced viewpoint of OPLL. I wish that this monograph represents a milestone in the
advancement of OPLL research and the legacy of Professor Hyun Jib Kim as a Korean spine surgeon.

Editor
Chun Kee Chung, M.D., Ph.D.

도서목차
Preface ··········· ix

01 Introduction 1
Historical Background···········································1
Japanese Era in OPLL Research·····························2
OPLL as a Subset of Enthesopathy·························4
OPLL beyond the Japanese Disease························5

02 Epidemiology of Ossification of the Posterior Longitudinal Ligament in Korea 9
Introduction·····9
Epidemiologic Studies of OPLL in Korean·········· 10
OPLL in Korean Patients with AS······················· 14
Prevalence and Association Factors of OPLL in Patients with SpA····························
16

03 Epidemiology of Ossification of the Posterior Longitudinal Ligament in Japan 19
Introduction··· 19
Incidence & Clinical Features······························ 20
Imaging········· 21

04 Epidemiology of Ossification of the Posterior Longitudinal Ligament in the Chinese Population 23
Introduction··· 23
Discussion······ 27

05 The Genetics and Molecular Research in Ossification of the Posterior Longitudinal Ligament 31
Introduction··· 31
Familial Surveys and Genetic Pattern Studies······· 32
NPPS············· 33
COL11A2 and COL6A1···································· 34
BMP-2 and TGF-b ············································· 35
Exogenous Factors May Contribute to OPLL······ 36
Miscellaneous· 37

06 Pathogenesis and Pathophysiology of Ossification of the Posterior Longitudinal Ligament 41
Introduction··· 41
Pathology of Ossified PLL··································· 42
Contributing Factors in the Pathogenesis of OPLL····································
··············· 44

07 Natural History of Ossification of the Posterior Longitudinal Ligament of Cervical Spine 53
Introduction··· 53
Issues in natural history······································· 54
Natural history of cervical OPLL at Seoul National University Hospital (SNUH)····· 63

08 Clinical Manifestations and Differential Diagnosis of Cervical Ossification of the Posterior Longitudinal Ligament 71
Introduction··· 71
Clinical Manifestation········································· 72
Differential Diagnosis·········································· 73

09 Radiologic Diagnosis and Novel MR Imaging Technologies for Ossification of the Posterior Longitudinal Ligament 77
Plain Radiograph················································ 77
Computed Tomography······································· 80
Magnetic Resonance Imaging····························· 82

10 Conservative Management of Ossification of the Posterior Longitudinal Ligament in the Cervical Spine 89
Introduction ·· 89
Natural Course of OPLL····································· 90
Dynamic Factors in Myelopathy Due to OPLL ·· 90
Extent of Compression of the Spinal Cord and Prognosis ································
········ 91
Indication of Conservative Treatment·················· 91
Conservative Treatment Methods ························ 92

11 Surgical Indication and Strategy for the Cervical Ossification of the Posterior Longitudinal Ligament: Evolution and
Outcome 97
Introduction··· 97
Indication······· 98
Anterior Surgery with Strut Fixation··················· 98
Posterior Approach – Myoarchitectonic Spino-Laminoplasty (MSLP) Technique ···· 102
Myoarchitectonic Spino-Laminoplasty (MSLP) – Biomechanical Efficacy ·············· 102
Myoarchitectonic Spino-Laminoplasty (MSLP) – Postoperative and Preoperative
Neck Pain· 105
Selection Criteria for Approaches – Principles and Strategy······························
······ 106
Combined Approach········································· 108
Salience in the Axial and Sagittal Planes:
Configuration of OPLL Likely to Result in Postoperative Deteriorations············· 108
Complications Statistics – Posterior Surgery······ 113

12 Anterior Surgical Approach for Ossification of the Posterior Longitudinal ligament in the Cervical Spine 117
Introduction· 117
Surgical Indication of Anterior Surgical Approach···································
··············· 118
Radiographic Criteria for Selection of Surgical Approach································
······· 118
Perioperative Preparations································· 119
Surgical Techniques··········································· 120
Complications··················································· 124

13 Posterior Surgical Approach for Ossification of the Posterior Longitudinal Ligament in the Cervical Spine 129
Introduction· 129
Indication for Surgical Treatment······················· 130
Choice of Surgical Procedures··························· 130
Posterior Decompression Procedures················· 131
Simultaneous Posterior Decompression and Fixation···································
··········· 132

14 An Alternative Surgical Approach for Cervical Ossification of the Posterior Longitudinal Ligament: Multilevel
Oblique Corpectomy Without Fusion 137
Introduction· 137
Indications and Planning··································· 138
Expected Complications···································· 141
Discussion and Practical Points·························· 142

15 Complications and Avoidance in the Surgical Treatments for Ossification of the Posterior Longitudinal Ligament in
the Cervical Spine 149
Introduction· 149
Complications During the Anterior Approach to OPLL Lesions ···························· 150
Complications of the Posterior Approach to OPLL Lesions ································
··· 158

16 Surgical Outcome and Prognostic Factors for Ossification of the Posterior Longitudinal Ligament in the Cervical
Spine 177
Introduction 177
Surgical Outcome············································· 178
Prognostic Factors············································· 181

17 Ossification of the Posterior Longitudinal Ligament in the Thoracic Spine and its Surgical Management 189
Introduction· 189
Etiology, Pathomechanism, and Classification of T-OPLL·································
······ 190
Surgical Methods·············································· 190
Surgical Outcomes············································ 195
Factors Related to Outcomes···························· 196
Complications··················································· 197

18 Relationship Between Diffuse Idiopathic Skeletal Hyperostosis and OPLL 201
Introduction· 201
Diffuse Idiopathic Skeletal Hyperostosis ············ 202
Associations of DISH and OPLL······················· 204

19 Relationship Between Ossification of the Posterior Longitudinal Ligament and Ossification of the Ligamentum Flavum
209
Introduction· 209
Paravertebral Ligamentous Ossification: OPLL, OLF and DISH······························
210

Index··········· 217