RELATIONSHIP BETWEEN PARAMETERS OF THE LUMBAR FACET JOINTS IN A LONG-TERM POSTOPERATIVE OUTCOME RELAÇÃO

ABSTRACT Objective: To analyze the impact of the relationship between tropism and angulation of the lower lumbar facet joints on a remote clinical outcome after dynamic and rigid surgical interventions. Methods: Patients with degenerative diseases of the lower lumbar spine were subdivided into three groups, according to the method of surgical treatment: 1) (n=48) the use of an artificial prosthesis intervertebral disc (IVD); 2) (n=42) the use of interbody fusion combined with transpedicular and transfacet stabilization; 3) (n=51) the use of interbody fusion and bilateral transpedicular stabilization. Analysis was performed of the remote clinical parameters and neuroimaging characteristics before the operation was performed. Results: When analyzing clinical and instrumental parameters, a significant correlation was found between the long-term outcomes of surgical treatment on the VAS and Oswestry scales and the neuroimaging data on angulation and tropism of the facet joints (FJ). Conclusions: The data obtained testify to the importance of preoperative diagnosis of tropism and angulation of the lower lumbar facet joint, which enables differentiated surgical tactics to be selected, and remote clinical outcomes to be optimized. In the presence of neuroimaging parameters of Facet Joint angulation of less than 600, regardless of the presence of tropism, it is possible to perform total arthroplasty of IVD. When neuroimaging parameters of Facet Joint angulation of more than 600 are detected, rigid stabilization of the operated segment is recommended, while in the absence of tropism of Facet Joints, a contralateral transfacetal fixation is possible; in the presence of tropism, it is expedient to perform bilateral transpedicular stabilization. Level of Evidence II; Prognostic Studies—Investigating the Effect of a Patient Characteristic on the Outcome of Disease.


INTRODUCTION
][4] It has been proven that degeneration of the adjacent level occurs as a result of increased load on the facet joints and intervertebral discs, which is associated with the development of pathological mobility of the vertebral-motor segment (VMS) above the level of the rigid stabilization. 1,2otential predisposing factors contributing to accelerated degeneration of the adjacent level are: degenerative changes in the joints of FJs, the type and extent of fusion, changes in the configuration of the spinal column in the sagittal plane, and previous surgical manipulations in the adjacent segment. 1,4railsford JF in 1928 first used the term "FJ tropism" to denote an asymmetry between the right and left FJs, or the presence of a more sagittal orientation of one of the FJs. 5 Masharawi et al. demonstrated that tropism of the FJs in the thoracic spine is one of the norm variants. 6][9] To select the right tactics for surgical treatment of patients with degenerative diseases of FJs, it is necessary to determine and justify the optimal amount of surgical intervention in the preoperative stage, taking into account individual degenerative changes of the FJs, the orientation of the joint surfaces and their angulation, the presence or absence of tropism for improvement of long-term postoperative clinical outcomes, minimization of postoperative instability, and the restoration of normal biomechanics for prevention of the progression of degenerate changes in lumbar segments. 2,10,11he specific aim of this study was to search for therapeutic and diagnostic approaches to optimize the outcomes of surgical treatment of patients with degenerative diseases of the lower lumbar spine, based on the analysis of the clinical and morphological parameters of the VMS.
The overall aim of this study was to analyze the impact of the relationship between tropism and angulation of the lower lumbar facet joints on a remote clinical outcome after dynamic and rigid surgical interventions, to determine the optimal surgical tactics.

METHODS
The study was approved by the ethics committee of the Irkutsk State Medical University; each of the patients included in the study gave written informed consent -protocol No. 2 by March 13, 2013.
A total of 151 patients who underwent in-patient treatment at the Center for Neurosurgery of the Railway Clinical Hospital at the Irkutsk-Passenger Railway station of the Russian Railways in the period 2013 to 2016.Three representative groups were singled out: in 48 cases, a discectomy was performed through extraperitoneal pararectal access with implantation of the M-6 disc prosthesis (Spinal Kinetics, USA) (I group); in 42 cases -interbody fusion was performed with the T-pal cage (Synthesys, Switzerland) using the TLIF method with the ipsilateral transpedicular stabilization by the Viper II system (Synthesys, Switzerland); contralateral fixation with the Facet Wedge implant (Synthesys, Switzerland).1) (n=48) the use of an artificial prosthesis intervertebral disc (IVD); 2) (n=42) the use of interbody fusion combined with transpedicular and transfacet stabilization; 3) (n=51) the use of interbody fusion and bilateral transpedicular stabilization.Exclusion and exclusion criteria for the study were indications and contraindications for the implementation of interbody fusion to treat clinically significant pathological mobility of the vertebral-motor segments.

Inclusion criteria
Ineffective conservative therapy, prolonged or recurrent pain syndrome, persistent neurological deficit caused by the phenomena of radicular pain to sciatica with peripheral paresis; Decrease in the height of the interbody spacing by more than 1/3 of the height of the overlying; Absence of signs of segment instability (segmental angulation > 10 o , linear translation > 4 mm); A one-level symptomatic degenerative disease of the lower lumbar spine, according to neuroimaging data.

Contraindications
Central stenosis of the spinal canal; Spondylolisthesis with or without spondylolysis; Severe concomitant pathology; Significant osteoporosis (decrease in BMD -by 2.8 or more according to the WHO T-criterion in 1995); Need to correct the sagittal balance; Need for a surgical correction of 2 or more segments of the lumbosacral spine.
Long-term clinical data were studied (the level of the pain syndrome according to the visual analogue scale (VAS) in the lumbar and lower limbs, the quality of life of the patients according to the questionnaire for patients with back pain Oswestry (ODI), satisfaction with the result of surgical treatment according to the Macnab scale, 3 and instrumental parameters determined by magnetic resonance imaging (MRI) of the lumbar spine (angulation and tropism of FJs) according to the method of Karacan et al. 12 .(Figure 1) Calculation of the angles of FJ was performed on axial MRI--grams, using the software RadiAnt DICOM Viewer.Tropism of FJs was verified in the presence of the difference between the values of the angles of the right and left FJs of more than 10 o .Values of the difference in angles between FJs at the level of surgical intervention were compared with those at the level of adjacent segments (i.e., for IVD of L III -L IV , the control level was L IV -L V , for L IV -L V -L III -L IV or L V -S I , and for IVD of L V -S I -L IV -L V ).
After the surgery, the follow-up catamnesis was at least 24 and a maximum of 48 months, with a median of 36 months.
To assess the significance of differences in the sample populations, the criteria of nonparametric statistics were used, and p <0.05 was taken as the lower limit for reliability.The data are represented by the median and interquartile range in the form of Me (25;75).

RESULTS
Analysis of gender characteristics of patients.General characteristics of the studied patients by sex, age, and constitutional characteristics are shown in Table 1.
It was found that the operated patients were predominantly male (more than 70%) and overweight (BMI > 25.0).
Analysis of remote clinical outcomes.Characteristics of distant parameters (after 24 months, on average) of patients in the study groups, in terms of the level of pain, quality of life and the degree of patient satisfaction with the surgery performed, are shown in Table 2.
Analyzing the long-term outcomes of surgical treatment (on average in 24 months) of the patients with degenerative diseases of the lower lumbar segments with the use of dynamic fixation (group I), interbody fusion with transpedicular and less rigid transfacetal stabilization (group II), and interbody fusion with rigid transpedicular stabilization (group III) , we obtained the minimum values for level of pain, on the visual analogue scale, good functional state, according to the ODI index, and predominantly good results on the Macnab scale of subjective satisfaction with surgical treatment outcome.
Analysis of clinical and morphological parameters of the affected vertebral-motor segments of patients, and their relationship with the outcome of surgical treatment.
The main clinical parameters that have a direct correlation with the clinical postoperative outcome and quality of life level are the degree of pain according to the VAS scale, and functional state according to the ODI index.Correlation analysis of the above clinical components and morphological characteristics -angulation and tropism of FJs according to the Karacan method was performed.Correlation dependence of the long-term outcome of surgical treatment according to VAS and ODI with the studied neuroimaging parameters is shown in Tables 3, 4.
In the analysis, it was found that the angulation index of FJs in group I was significantly correlated with the clinical parameters of VAS and ODI, the correlation dependence with the index of tropism was absent; in group II and III, an inverse correlation was observed with all the parameters studied, except for the tropism of FJs, where a direct significant correlation was verified.
In the analysis, it was found that the index of tropism of FJs in group I did not significantly correlate with the studied parameters; in groups II and III, an inverse correlation was observed with all the clinical parameters studied, and a significant inverse correlation with tropism of FJs.
Thus, the value of FJ angulation and, in some cases, the significance of the tropism of FJs, determined by the MRI method, have a direct impact on long-term clinical outcomes, which, perhaps, makes it possible to determine the possible tactics of surgical treatment.Postoperative outcomes were categorized as follows: "good": a complete or near complete return to the former level of social and physical activity (before the onset of the disease or the last exacerbation) (possible limitation of major physical activity); "unsatisfactory": household and social activity is not fully restored, no effect from the surgery or deterioration of the state.
A comparison of the clinical and instrumental data of patients in the study groups is presented in Table 5.
Taking into account the degree of the impact of the investigated instrumental parameters on the remote clinical outcome for optimization of treatment tactics for patients with degenerative diseases of the lower lumbar spine, it was determined that: In the group of patients operated according to the dynamic fixation method, minimum VAS and ODI scores and a smaller degree of degenerative changes in the adjacent segment were achieved with preoperative parameters of FJs: angulation < 60 0 , regardless of the presence of tropism.(Figure 2) In the group of patients operated by the method of rigid stabilization, minimum VAS and ODI scores and a smaller degree of     degenerative changes in the adjacent segment were achieved with preoperative parameters of FJs: angulation > 60 o , while in the absence of FJ tropism, a contralateral transfacetal fixation is possible (Figure 3), and in the presence of tropism, it is advisable to perform bilateral transpedicular stabilization.(Figure 4)

DISCUSSION
Currently, approaches to surgical treatment of patients with different degrees of degenerative diseases of FJs are not well defined. 2,3arious surgical interventions for degenerative FJ diseases are performed in spinal surgery, ranging from minimally invasive puncture techniques to partial or total facetectomy with rigid stabilization, with ambiguous results. 1,13,14This is primarily due to the lack of objective indications for choosing the type of surgical treatment, and a failure to take into account the individual anatomical features of FJs. 2,3ith minimum degenerative changes of FJs -I-II degree according to the classification of Fujiwara A., 2 conservative treatment is used, which is analogous to the therapeutic principle that osteoarthritis in any location consists in the use of non-steroidal anti-inflammatory drugs, hormonal anti-inflammatory therapy, drugs-chondroprotectors, and physiotherapy. 11Minimally-invasive methods of treatment include the use of paravertebral blockades, radiofrequency, laser, chemodenervation of FJs, and puncture of FJs with the use of a synovial fluid prosthesis (facetoplasty). 2,3,10  With significant degenerative changes in FJs and the ineffectiveness of conservative treatment, a radical method of treatment is used -facetectomy followed by instrumental fixation of VMS. 2,4he accumulated experience of the adverse consequences of the use of interbody fusion and transpedicular stabilization contributes to the detailing of postoperative complications and the development of measures aimed at preventing their development. 15][18] In a number of cases, the development of postoperative pain syndrome is associated with impulse from the nociceptors of the IVD, which is caused by an increased load on the closure plates after the implantation of the cage, which is significantly higher than in the unchanged IVD. 19,207][18][19][20][21] Gibson et al. found that 32% of cases in the late postoperative period developed pseudoarthrosis, accompanied by unsatisfactory clinical outcomes and instrumental signs of pathological mobility. 21In addition, Gibson et al. showed that the high frequency of bone block formation is not correlated with long-term clinical outcomes. 22Unsatisfactory long-term clinical outcomes associated with the development of the syndrome of the adjacent segment, postoperative instability, pseudoarthrosis and scar intracanal changes have prompted researchers to search for the key factors that cause their development.4][25] However, no correlation has been made with the remote clinical outcomes of these neuroimaging parameters.
4][25] However, to our knowledge, there is no study to date on the possible correlation of these morphometric parameters with a remote clinical outcome.
For the first time, Farfan H. et al. revealed a significant correlation between tropism of FJs and the formation of IVD hernias in the lumbosacral spine. 24Also, the authors point out that the hernias of the lumbar IVD appear on the side of FJs with the smallest angle, since with this orientation of FJs, it is not capable of reducing torsion loads affecting on the fibrous ring during movement. 16,25linical studies are currently underway to investigate the relationship between tropism and the orientation of FJs with the onset of degenerative spondylolisthesis. 23,25oden S. et al. 26 studied FJ angulations on MRI images from 140 patients and found that a more sagittal location and tropism of FJs contribute to the formation of degenerative spondylolisthesis.
Cinotti G. et al. according to CT data of 54 patients revealed a significant correlation between asymmetric of FJs and degenerative spondylolisthesis at the level of L IV -L V , L V -S I. 27 Thus, the parameters of angulation and tropism of FJ can serve as objective criteria for a possible choice of surgical tactics, and for predicting a remote postoperative clinical outcome in patients with degenerative diseases of the lower lumbar VMS.

CONCLUSIONS
A comprehensive clinical and instrumental examination including lumbar spondylography, magnetic resonance imaging for objective analysis of morphostructural changes in the VMS is recommended for all patients with degenerative diseases of the lower lumbar spine.
The use of angulation and tropism parameters of FJs, which are determined by a non-invasive MRI method, enable the degree of degeneration of the anterior (IVD) and posterior (FJ) support complexes of the lower lumbar segments to be established, and possible tactics determined.
In the presence of neuroimaging parameters of angulation of FJs less than 60 o , regardless of the presence of tropism, it is possible to perform total arthroplasty of IVD.
When detecting neuroimaging parameters of FJs angulation more than 60 o , rigid stabilization of the operated segment is recommended, while in the absence of FJs tropism, a contralateral transfacetal fixation is possible; in the presence of tropism, it is expedient to perform bilateral transpedicular stabilization.

Figure 1 .
Figure 1.The procedure for calculating the angles of FJ by the method of Karacan et al. using the program RadiAnt DICOM Viewer: the angle of FJs is formed by the intersection of the lines drawn through the middle of the articular cleft of FJs and the line drawn through the center of the IVD and coinciding with the axis of the spinous process.

Figure 2 .
Figure 2. Patient A., 34 years old.MRI of the lumbosacral spine, T2 weighted images: A -axial projection: angulation of FJs -58 o , no tropism; B -sagittal projection (arrow indicates Hernia of IVD L V -S I ); D -axial projection after surgery -total arthroplasty of L V -S I with artificial prosthesis IVD M6; C -sagittal projection after surgery.The level of pain in the lumbar spine according to VAS before surgery was 82 mm, in the left lower limb -86 mm, ODI -64 scores.The level of pain in the lumbar spine according to VAS in 24 months after the surgery was 6 mm, in the left lower limb VAS was 2 mm, ODI -8 scores.

Figure 3 .
Figure 3. Patient G., 39 years old.MRI of the lumbosacral spine, T2 weighted images: A -axial projection: angulation of FJ -63 o , no tropism; B -sagittal projection (arrow indicates Hernia of IVD L V -S I ); C -axial projection after surgery in the volume of microsurgical discectomy L V -S I , interbody fusion L V -S I ., transpedicular fixation L V -S I by the system of cannulated screws on the left, contralateral transfacetal fixation by Facet Wedge system on the right; D -sagittal projection after surgery.The level of pain in the lumbar spine according to VAS before surgery was 77 mm, in the left lower limb -81 mm, ODI -62 scores.The level of pain in the lumbar spine according to VAS in 24 months after the surgery was 6 mm, in the left lower limb -4 mm, ODI -4 scores.

Figure 4 .
Figure 4. Patient P., 39 years old.MRI of the lumbosacral spine, T2 weighted images: a -axial projection: angulation of FJ -65 o , tropism is present; b -sagittal projection (arrow indicates Hernia of IVD L V -S I ); c -axial projection after surgery in the volume of microsurgical discectomy L V -S I , interbody fusion L V -S I ., transpedicular fixation L V -S I by the system of cannulated screws; d -sagittal projection after surgery.The level of pain in the lumbar spine according to VAS before surgery was 78 mm, and in the left lower limb, 72 mm, ODI -62 scores.The level of pain in the lumbar spine according to VAS in 24 months after the surgery was 4 mm, and in the left lower limb, 3 mm, ODI -8 scores.

Table 1 .
The distribution of the patients by sex, age, and constitutional characteristics.
Note: BMI -body weight index.

Table 2 .
Distribution of the studied patients for long-term results of surgical treatment.

Table 3 .
Correlation of the FJ angulation index with remote clinical parameters by VAS and ODI and tropism index of FJ.
Note: R -the correlation index; p -confidence probability.

Table 4 .
Correlation of tropism index of FJ with remote clinical parameters according to VAS and ODI and FJ angulation index.

Table 5 .
Comparative analysis of clinical data depending on the postoperative outcome in patients of the study groups.