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Inter- and intra-observer variability of a cervical OPLL classification using reconstructed CT images.

Chang H, Kong CG, Won HY, Kim JH, Park JB - Clin Orthop Surg (2010)

Bottom Line: The lateral radiograph-based system described by Tsuyama is used widely to classify ossification of the posterior longitudinal ligament (OPLL) of the cervical spine.Furthermore, its reliability among spine surgeons has not been investigated.The kappa values were used to assess the statistical reliability.

View Article: PubMed Central - PubMed

Affiliation: Spine Center, Mirae Hospital, Ulsan, Korea.

ABSTRACT

Background: The lateral radiograph-based system described by Tsuyama is used widely to classify ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. However, OPLL is a complex 3-dimensional (3-D) lesion, not a simple and uniplanar one, which is often difficult to identify on a lateral radiograph. Furthermore, its reliability among spine surgeons has not been investigated. Given the popularity of a reconstructed computed tomography (CT), this study examined the inter- and intra-observer reliability of lateral radiograph-based OPLL classification using that modality.

Methods: Five spine surgeons independently reviewed the lateral radiograph, axial CT, 2-D (sagittal) and 3-D reconstructed CT images of 108 OPLL patients on 2 separate occasions. Based on these images, the reviewers classified each OPLL case according to the Tsuyama's system. The kappa values were used to assess the statistical reliability.

Results: The inter- and intra-observer kappa values were only 0.51 and 0.67 for the lateral radiograph, even in combination with the axial CT images, 0.70 and 0.85 for 2-D CT images, and 0.76 and 0.86 for 3-D CT images, respectively. These kappa values showed a good-to-excellent range for the 2-D and 3-D reconstructed CT images while those of the lateral radiograph indicated a fair range. According to the OPLL types, the inter- and intra-observer reliability was low in the continuous type and high in the circumscribed type on the lateral radiograph. However, the low reliability of the continuous type on lateral radiograph was overcome somewhat using 2-D and 3-D reconstructed CT images.

Conclusions: The inter- and intra-observer kappa values were only 0.51 and 0.67 for the lateral radiograph, even in combination with the axial CT images, 0.70 and 0.85 for 2-D CT images, and 0.76 and 0.86 for 3-D CT images, respectively. These kappa values showed a good-to-excellent range for the 2-D and 3-D reconstructed CT images while those of the lateral radiograph indicated a fair range. According to the OPLL types, the inter- and intra-observer reliability was low in the continuous type and high in the circumscribed type on the lateral radiograph. However, the low reliability of the continuous type on lateral radiograph was overcome somewhat using 2-D and 3-D reconstructed CT images.

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Sixty-one-yr-old male patient presented with the typical clinical symptoms of cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL). Most reviewers classified this case into the continuous type OPLL extending C1 to C7 using the lateral radiograph in combination with the axial CT images (A). However, the 2-dimensional (2-D) and 3-D CT reconstructed images showed an interrupted OPLL at the C4-C5 disc level (arrow) (B). Most of the reviewers re-classified this case into the mixed type OPLL extending C1 to C7 using the reconstructed CT images.
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Figure 1: Sixty-one-yr-old male patient presented with the typical clinical symptoms of cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL). Most reviewers classified this case into the continuous type OPLL extending C1 to C7 using the lateral radiograph in combination with the axial CT images (A). However, the 2-dimensional (2-D) and 3-D CT reconstructed images showed an interrupted OPLL at the C4-C5 disc level (arrow) (B). Most of the reviewers re-classified this case into the mixed type OPLL extending C1 to C7 using the reconstructed CT images.

Mentions: According to the OPLL types, the inter- and intra-observer reliability in the lateral radiographs in combination with axial CT images was low in the continuous type and high in the circumscribed type. The greatest difficulty encountered by the reviewers was distinguishing the continuous type from the mixed type. However, this difficulty of the lateral radiographs in combination with the axial CT images was overcome somewhat using the 2-D and 3-D reconstructed CT images. In particular, as shown in Fig. 1, most of the continuous types classified by the lateral radiograph in combination with the axial CT images were changed into the mixed type using the 2-D and 3-D reconstructed CT images. The 3-D complex ossified structures of cervical OPLL were well described with the 2-D and 3-D reconstructed CT images. Therefore, it is important to classify cervical OPLL using reconstructed CT images. However, there are no reports classifying the OPLL type using reconstructed CT images. Therefore, this is the first study to determine the cervical OPLL type by 2-D and 3-D CT reconstructions. In conclusion, these results suggest that a lateral radiograph- based classification of cervical OPLL does not have sufficient inter- and intra-observer reliability to portray the OPLL type accurately. Therefore, 2-D and/or 3-D morphologic analysis of OPLL is recommended to determine the appropriate surgical approach, extent and need for additional fusion.


Inter- and intra-observer variability of a cervical OPLL classification using reconstructed CT images.

Chang H, Kong CG, Won HY, Kim JH, Park JB - Clin Orthop Surg (2010)

Sixty-one-yr-old male patient presented with the typical clinical symptoms of cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL). Most reviewers classified this case into the continuous type OPLL extending C1 to C7 using the lateral radiograph in combination with the axial CT images (A). However, the 2-dimensional (2-D) and 3-D CT reconstructed images showed an interrupted OPLL at the C4-C5 disc level (arrow) (B). Most of the reviewers re-classified this case into the mixed type OPLL extending C1 to C7 using the reconstructed CT images.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2824098&req=5

Figure 1: Sixty-one-yr-old male patient presented with the typical clinical symptoms of cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL). Most reviewers classified this case into the continuous type OPLL extending C1 to C7 using the lateral radiograph in combination with the axial CT images (A). However, the 2-dimensional (2-D) and 3-D CT reconstructed images showed an interrupted OPLL at the C4-C5 disc level (arrow) (B). Most of the reviewers re-classified this case into the mixed type OPLL extending C1 to C7 using the reconstructed CT images.
Mentions: According to the OPLL types, the inter- and intra-observer reliability in the lateral radiographs in combination with axial CT images was low in the continuous type and high in the circumscribed type. The greatest difficulty encountered by the reviewers was distinguishing the continuous type from the mixed type. However, this difficulty of the lateral radiographs in combination with the axial CT images was overcome somewhat using the 2-D and 3-D reconstructed CT images. In particular, as shown in Fig. 1, most of the continuous types classified by the lateral radiograph in combination with the axial CT images were changed into the mixed type using the 2-D and 3-D reconstructed CT images. The 3-D complex ossified structures of cervical OPLL were well described with the 2-D and 3-D reconstructed CT images. Therefore, it is important to classify cervical OPLL using reconstructed CT images. However, there are no reports classifying the OPLL type using reconstructed CT images. Therefore, this is the first study to determine the cervical OPLL type by 2-D and 3-D CT reconstructions. In conclusion, these results suggest that a lateral radiograph- based classification of cervical OPLL does not have sufficient inter- and intra-observer reliability to portray the OPLL type accurately. Therefore, 2-D and/or 3-D morphologic analysis of OPLL is recommended to determine the appropriate surgical approach, extent and need for additional fusion.

Bottom Line: The lateral radiograph-based system described by Tsuyama is used widely to classify ossification of the posterior longitudinal ligament (OPLL) of the cervical spine.Furthermore, its reliability among spine surgeons has not been investigated.The kappa values were used to assess the statistical reliability.

View Article: PubMed Central - PubMed

Affiliation: Spine Center, Mirae Hospital, Ulsan, Korea.

ABSTRACT

Background: The lateral radiograph-based system described by Tsuyama is used widely to classify ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. However, OPLL is a complex 3-dimensional (3-D) lesion, not a simple and uniplanar one, which is often difficult to identify on a lateral radiograph. Furthermore, its reliability among spine surgeons has not been investigated. Given the popularity of a reconstructed computed tomography (CT), this study examined the inter- and intra-observer reliability of lateral radiograph-based OPLL classification using that modality.

Methods: Five spine surgeons independently reviewed the lateral radiograph, axial CT, 2-D (sagittal) and 3-D reconstructed CT images of 108 OPLL patients on 2 separate occasions. Based on these images, the reviewers classified each OPLL case according to the Tsuyama's system. The kappa values were used to assess the statistical reliability.

Results: The inter- and intra-observer kappa values were only 0.51 and 0.67 for the lateral radiograph, even in combination with the axial CT images, 0.70 and 0.85 for 2-D CT images, and 0.76 and 0.86 for 3-D CT images, respectively. These kappa values showed a good-to-excellent range for the 2-D and 3-D reconstructed CT images while those of the lateral radiograph indicated a fair range. According to the OPLL types, the inter- and intra-observer reliability was low in the continuous type and high in the circumscribed type on the lateral radiograph. However, the low reliability of the continuous type on lateral radiograph was overcome somewhat using 2-D and 3-D reconstructed CT images.

Conclusions: The inter- and intra-observer kappa values were only 0.51 and 0.67 for the lateral radiograph, even in combination with the axial CT images, 0.70 and 0.85 for 2-D CT images, and 0.76 and 0.86 for 3-D CT images, respectively. These kappa values showed a good-to-excellent range for the 2-D and 3-D reconstructed CT images while those of the lateral radiograph indicated a fair range. According to the OPLL types, the inter- and intra-observer reliability was low in the continuous type and high in the circumscribed type on the lateral radiograph. However, the low reliability of the continuous type on lateral radiograph was overcome somewhat using 2-D and 3-D reconstructed CT images.

Show MeSH
Related in: MedlinePlus