The biomechanical influence of the facet joint orientation and the facet tropism in the lumbar spine

Background contextFacet joint orientation and facet tropism (FT) are presented as the potential anatomical predisposing factors for lumbar degenerative changes that may lead in turn to early degeneration and herniation of the corresponding disc or degenerative spondylolisthesis. However, no biomechanical study of this concept has been reported.PurposeTo investigate the biomechanical influence of the facet orientation and FT on stress on the corresponding segment.Study designFinite element analysis.MethodsThree models, F50, F55, and F60 were simulated with different facet joint orientations (50°, 55°, and 60° relative to coronal plane) at both L2–L3 facet joints. A FT model was also simulated to represent a 50° facet joint angle at the right side and a 60° facet joint angle at the left side in the L2–L3 segment. In each model, the intradiscal pressures were investigated under four pure moments and anterior shear force. Facet contact forces at the L2–L3 segment were also analyzed under extension and torsion moments and anterior shear force. This study was supported by 5000 CHF grant of 2011 AO Spine Research Korea fund. The authors of this study have no topic-specific potential conflicts of interest related to this study.ResultsThe F50, F55, and F60 models did not differ in the intradiscal pressures generated under four pure moments: but under anterior shear force, the F60 and FT models showed increases of intradiscal pressure. The F50 model under extension and the F60 model under torsion each generated an increase in facet contact force. In all conditions tested, the FT model yielded the greatest increase of intradiscal pressure and facet contact force of all the models.ConclusionsThe facet orientation per se did not increase disc stress or facet joint stress prominently at the corresponding level under four pure moments, but FT could make the corresponding segment more vulnerable to external moments or anterior shear force.     

腰椎椎弓根螺钉置入对近端相邻关节突关节侵扰的影响因素研究进展

<正>腰椎相邻节段退变(adjacent segment degeneration,ASD)是腰椎椎弓根螺钉置入术后最常见的远期并发症之一,包括相邻椎间盘退变、关节突关节退变、椎体滑脱、椎管狭窄、椎体压缩性骨折等~([1、2])。其中近端相邻关节突关节的退变既非常常见,又容易导致新的临床症状产生,且较远端相邻节段发生更早、更明显~([3、4])。目前研究认为,腰椎椎弓根螺钉置入对近端相邻关节突关节侵扰(facet joint violation,FJV)是加速关节突关节退变的重要危险因素之     

In vivo facet joint loading of the canine lumbar spine.

This study describes a technique to measure in vivo loads and the resultant load-contact locations in the facet joint of the canine lumbar spine. The technique is a modification of a previously described in vitro method that used calibrated surface strains of the lateral aspect of the right L3 cranial articular process. In the present study, strains were measured during various in vivo static and dynamic activities 3 days after strain gage implantation. The in vivo recording technique and its errors, which depend on the location of the applied facet loads, is described. The results of applying the technique to five dogs gave the following results. Relative resultant contact load locations on the facet tended to be in the central and caudal portion of the facet in extension activities, central and cranial in standing, and cranial and ventral in flexion or right-turning activities. Right-turning contact locations were ventral and cranial to left-turning locations. Resultant load locations at peak loading during walking were in the central region of the facet, whereas resultant load locations at minimum loading during walking were relatively craniad. This resultant load-contact location during a walk gait cycle typically migrated in an arc with a displacement of 4 mm from minimum to maximum loading. Static tests resulted in a range of facet loads of 0 N in flexion and lying to 185 N for two-legged standing erect, and stand resulted in facet loads of 26 +/- 15 N (mean +/- standard deviation [SD]). Dynamic tests resulted in peak facet loads ranging from 55 N while walking erect to 170 N for climbing up stairs. Maximum walk facet loads were 107 +/- 27 N. The technique is applicable to in vivo studies of a canine facet joint osteoarthritis model and may be useful for establishing an understanding of the biomechanics of low-back pain.     

Ultrasound guidance for facet joint injections in the lumbar spine: a computed tomography-controlled feasibility study

We conducted this study to develop an ultrasound-guided approach for facet joint injections of the lumbar spine. Five zygapophyseal joints (L1-S1) on each side of 5 embalmed cadavers were examined by ultrasound for a total of 50 examinations. The joint space was demonstrated under ultrasound guidance. The midpoint of the joint space, defined as the middle of its cranio-caudal extension on its dorsal surface, was taken as a reference point, and its position was computed from its depth and lateral distance from the spinous process. Forty-two of 50 approaches could be clearly visualized. Subsequently, these distances were compared to those obtained by computed tomography (CT). To assess the efficacy of ultrasound in the needle placement, all lumbar facet joints were approached in one embalmed cadaver. The exact placement of the needle tips was again evaluated by CT. Ultrasound and CT measurements showed the same mean depth and lateral distance to the reference point, 3.15 +/- 0.5 cm and 1.9 +/- 0.6 cm, respectively. Pearson's coefficient of correlation was 0.86 (P < 0.0001) between ultrasound and CT. All 10 needle tips were within the joint space during simulated facet joint injections. We conclude that ultrasound guidance might be a useful adjunct for facet joint injections in the lumbar spine. IMPLICATIONS: This study was designed to develop an ultrasound-guided approach to the facet joints of the lumbar spine and to assess its feasibility and accuracy by means of a comparison to computed tomography images. The imaging study demonstrated a significant correlation between ultrasound and computed tomography measurements. During simulated facet injection, ultrasound guidance consistently resulted in accurate needle placement.     

Development of an in vivo method to investigate biomechanical and neurophysiological properties of spine facet joint capsules

Facet joint capsules (FJC) may experience large mechanical deformation under spine motion. There has been no previous quantitative study of the relationship between capsular strain and sensory nerve activation in spine FJC in vivo. Space limitation in the cervical spine makes such a study difficult, as the facet joint must be loaded while simultaneously monitoring nerve discharge from nerve roots immediately adjacent to the loaded tissue. A new methodology was developed to investigate biomechanical and neurophysiological properties of spine facet joint capsules in vivo. The method incorporated a custom-fabricated testing frame for facet joint loading, a stereoimaging system, and a template-matching technique to obtain single afferent response. It was tested by loading goat C5–C6 FJC in vivo with simultaneous nerve root recordings and 3D strain tracking of the capsules. Preliminary data showed that 18 of 23 afferents (78.3%) were found to be mechanosensitive to tensile stretch, and five were not responsive, even under tensile load as high as 27.5 N. Mechanosensitive afferents in goat capsules had tensile strain thresholds of 0.119±0.080. Neural responses of all mechanosensitive units showed statistically significant correlations (all P<<0.05) with both capsular load (r²=0.744±0.109) and local strain (r²=0.868±0.088). This method enables the investigation of the correlation between tissue load, deformation and neural responses of mechanoreceptors in spine facet joint capsules, and can be adapted to investigate tissue loading and neural response of other soft tissues.     

Translaminar facet joint screws to enhance segmental fusion of the lumbar spine

Summary From 1984 to 1988, 70 consecutive lumbar and lumbosacral spine fusions enhanced with translaminar facet joint screws were performed for segmental degenerative disease. Twenty patients had partial decompression of central stenosis, 15 concomitant discectomy, and 19 lateral nerve root decompression. The mean time to fusion was 4.5 months (range 2–7 months). At follow-up (average 45 months; range 24–74 months) 98.5% were judged to have solid fusion. Satisfactory results were observed in 84% of cases, 91% without previous surgery and 75% after previous discectomy. Supplementation of posterolateral fusion by translaminar facet screws significantly improved time to fusion, fusion rate, and clinical outcomes with no significant increased complications.     

Anomalous ossicle in a lumbar facet joint

A case of an anomalous ossicle in a lumbar facet joint is reported and the operative findings presented. The nature of the anomaly is not fully understood but is thought to be the result of non-fusion between a normal appearing ossification center and the adjacent articular process. The patient's symptoms--severe chronic low back pain--subsided completely after surgery. It is concluded that the presence of such ossicles in facet joints in some cases may lead to severe symptoms and that surgical treatment in such cases should be considered.     

Ultrasound-guided versus computed tomography-controlled facet joint injections in the lumbar spine: a prospective randomized clinical trial

BACKGROUND AND OBJECTIVES: Facet joint injections are widely used for alleviation of back pain. Injections are preferentially performed as fluoroscopy or computed tomography (CT)-controlled interventions. Ultrasound provides real-time monitoring, does not produce ionizing radiation, and is broadly available. METHODS: We studied feasibility, accuracy, time-savings, radiation doses, and pain relief of ultrasound-guided facet joint injections versus CT-controlled interventions in a prospective randomized clinical trial. Forty adult patients with chronic low back pain were consecutively enrolled and evenly assigned to an ultrasound or a CT- group. RESULTS: Eighteen subjects from the group randomized to ultrasound were judged to be feasible for this type of approach. In 16 of them the facet joints were clearly visible and all of the associated facet joint injections were performed correctly. The duration of procedure and radiation dose was 14.3 +/- 6.6 minutes and 14.2 +/- 11.7 mGy.cm in the ultrasound group, and 22.3 +/- 6.3 minutes and 364.4 +/- 213.7 mGy.cm in the CT group. Both groups showed a benefit from facet joint injections. CONCLUSIONS: The ultrasound approach to the facet joints in the lumbar spine is feasible with minimal risks in a large majority of patients and results in a significant reduction of procedure duration and radiation dose.     

The effect of disc degeneration and facet joint osteoarthritis on the segmental flexibility of the lumbar spine

STUDY DESIGN: A biomechanical and imaging study of human cadaveric spinal motion segments. OBJECTIVE: To investigate the effect of both disc degeneration and facet joint osteoarthritis on lumbar segmental motion. SUMMARY OF BACKGROUND DATA: Spinal degeneration includes the osteoarthritic changes of the facet joint as well as disc degeneration. Disc degeneration has been reported to be associated with spinal motion. The association of facet joint osteoarthritis with lumbar segmental motion characteristics and the combined influence of disc degeneration and facet osteoarthritis has not yet been investigated. METHODS: A total of 110 lumbar motion segments (52 female, 58 male) from 44 human lumbar spines were studied (mean age = 69 years). Magnetic resonance images were used to assess the disc degeneration from Grade I (normal) to Grade V (advanced) and the osteoarthritic changes in the facet joints in terms of cartilage degeneration, subchondral sclerosis, and osteophytes. Disc height, endplate size, and facet joint orientation and width also were measured from the computed tomographic images. Rotational movements of the motion segment in response to the flexion, extension, lateral bending, and axial rotational moments were measured using a three-dimensional motion analysis system. RESULTS: Female motion segments showed significantly greater motion (lateral bending: P < 0. 001, flexion: P < 0.01, extension: P < 0.05) and smaller endplate size (P < 0.001) than male ones. The segmental motion increased with increasing severity of disc degeneration up to Grade IV, but decreased in both genders when the disc degeneration advanced to Grade V. In male segments, the disc degeneration-related motion changes were significant in axial rotation (P < 0.001), lateral bending (P < 0.05), and flexion (P < 0.05), whereas female segments showed significant changes only in axial rotation (P < 0.001). With cartilage degeneration of the facet joints, the axial rotational motion increased, whereas the lateral bending and flexion motion decreased in female segments. In male segments, however, motion in all directions increased with Grade 3 cartilage degeneration and decreased with Grade 4 cartilage degeneration. Subchondral sclerosis significantly decreased the motion (female: axial rotation, P < 0. 05; extension, P < 0.05 vs.- male:flexion,P < 0.05). Severity of osteophytes had no significant association with the segmental motion. CONCLUSION: Axial rotational motion was most affected by disc degeneration, and the effects of disc degeneration on the motion were similar between genders. Facet joint osteoarthritis also affected segmental motion, and the influence differed for male and female spines. Further studies are needed to clarify whether the degenerative process of facet joint osteoarthritis differs between genders and how facet joint osteoarthritis affects the stability of the spinal motion segment.     

椎间盘退变和关节突关节骨性关节炎对腰椎稳定性的影响

目的 探讨腰椎退变过程中，腰椎间盘退变、关节突关节骨性关节炎与腰椎稳定性之间的关系。方法 对78名腰椎退变患者进行腰椎MRI和动力位X线摄影。腰椎不稳分为椎间角度运动不稳、旋转不稳和椎间位移不稳，其中椎间位移不稳细分为：前向不稳、后向不稳和前后向不稳。腰椎间盘退变依据矢状位T2加权像分为5级；关节突关节骨性关节炎依据水平位T1加权像分为4级。对资料进行统计分析。结果 腰椎椎间角度运动不稳和前后向椎间位移不稳与关节突关节骨性关节炎存在显著负相关，前向椎间位移不稳与腰椎关节突关节骨性关节炎和椎间盘退变呈显著正相关，腰椎矢状面旋转不稳与腰椎关节突关节骨性关节炎无显著相关。结论 腰椎间盘退变和腰椎关节突关节骨性关节炎可影响腰椎运动节段的稳定性。     

Anomalous ossicle in a lumbar facet joint

Summary A case of an anomalous ossicle in a lumbar facet joint is reported and the operative findings presented. The nature of the anomaly is not fully understood but is thought to be the result of non-fusion between a normal appearing ossification center and the adjacent articular process. The patient's symptoms — severe chronic low back pain — subsided completely after surgery. It is concluded that the presence of such ossicles in facet joints in some cases may lead to severe symptoms and that surgical treatment in such cases should be considered.

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Zusammenfassung Es wird über einen Fall mit einem anomalen Ossikel eines lumbalen Wirbelgelenkes berichtet und der operative Befund präsentiert. Die Natur dieser Anomalie ist nicht geklärt, aber es wird vermutet, daß dies das Resultat einer nicht stattgefundenen Fusion zwischen einem normalen Ossifikationszentrum und dem benachbarten Gelenkfortsatz darstellt. Die Symptome, starke chronische Rückenschmerzen, verschwanden nach der Operation vollständig. Daraus wird geschlossen, daß ein solches Ossikel in einem Fazettengelenk in manchen Fällen eine schwere Symptomatik hervorrufen kann und daß man dann eine operative Behandlung ins Auge fassen sollte.

     

The biomechanical impact of facet tropism on the intervertebral disc and facet joints in the cervical spine

Background Context

Facet tropism is defined as the angular difference between the left and the right facet orientation. Facet tropism was suggested to be associated with the disc degeneration and facet degeneration in the lumbar spine. However, little is known about the relationship between facet tropism and pathologic changes in the cervical spine and the mechanism behind.

The relationship between facet joint osteoarthritis and disc degeneration of the lumbar spine: an MRI study

The role of MRI in assessing facet joint osteoarthritis is unclear. By developing a grading system for severity of facet joint osteoarthritis on MRI, the relationship between disc degeneration and facet joint osteoarthritis was determined. The accuracy of MRI in assessing facet joint osteoarthritis against CT was 94%. Under 40 years of age, the degree of disc degeneration varied among individuals. Over the age of 60, most of the discs were markedly degenerated. Under 40 years of age osteoarthritic changes in facet joints were minimal. Over the age of 60, variable degrees of facet joint osteoarthritis were observed but some facets did not show osteoarthritis. No facet joint osteoarthritis was found in the absence of disc degeneration and most facet joint osteoarthritis appeared at the intervertebral levels with advanced disc degeneration. Disc degeneration is more closely associated with aging than with facet joint osteoarthritis. The present study supports the hypothesis that “disc degeneration precedes facet joint osteoarthritis”, and also supports the concept that it may take 20 or more years to develop facet joint osteoarthritis following the onset of disc degeneration. Received: 1 March 1999 Revised: 27 May 1999 Accepted: 4 June 1999     

Enhancement of lumbar spine fusion by use of translaminar facet joint screws

From January 1983 to March 1986 the authors have performed 88 consecutive lumbosacral spine fusion, enhanced with translaminar facet screws, as described by F. Magerl of St. Gallen, Switzerland. Forty-three patients have a follow-up of 12 months or greater, for a mean follow-up time of 16 months. The median time to fusion in this group was 6 months, with a range of 6 weeks to 10 months. Ninety-three percent of the patients were found to be clinically improved, and 91% of patients were judged solidly fused on evaluation of motion radiographs. Compared with our previously reported results for lumbar fusion without internal fixation, supplementation of lumbar fusion by translaminar facet screw fixation significantly improved the clinical results, as well as the time required for fusion, with no significant increased risk.     

Pyogenic arthritis of a lumbar facet joint

We herein report the case of a 68-year-old man with diabetes who developed pyogenic arthritis of a lumbar facet joint after spinal injection. We performed magnetic resonance imaging (MRI), computed tomography (CT), technetium 99 methylene diphosphonate scintigraphy, and single photon emission computed tomography (SPECT) for this patient. MRI showed a lesion in the facet joint and no evidence of spondylodiscitis. CT showed a swelling of periarticular soft tissue around the facet joint. Bone scintigraphy showed a characteristic vertical uptake. In particular, SPECT was able to clearly confirm the location of the infection. An infection of the facet joint has only been rarely reported, but we recommended that this area should be carefully evaluated whenever a patient develops an infection of the lumbar spine after a spinal injection.     

The biomechanical influence of anterior vertebral body osteophytes on the lumbar spine: A finite element study

BACKGROUND CONTEXT

Anterior vertebral body osteophytes are common with degeneration but their biomechanical influence on the whole lumbar spine remains unclear.