Julien Rigal

Equilibrium of the human body and the gravity line: the basics.

IntroductionBipedalism is a distinguishing feature of the human race and is characterised by a narrow base of support and an ergonomically optimal position thanks to the appearance of lumbar and cervical curves.MaterialsThe pelvis, adapted to bipedalism, may be considered as the pelvic vertebra connecting the spine to the lower limbs. Laterally, the body’s line of gravity is situated very slightly behind the femoral heads laterally, and frontally it runs through the middle of the sacrum at a point equidistant from the two femoral heads.ResultsAny abnormal change through kyphosis regarding the spinal curves results in compensation, first in the pelvis through rotation and then in the lower limbs via knee flexion. This mechanism maintains the line of gravity within the base of support but is not ergonomic. To analyse sagittal balance, we must thus define the parameters concerned and the relationships between them.ConclusionThese parameters are as follows: for the pelvis: incidence angle, pelvis tilt, sacral slope; for the spine: point of inflexion, apex of lumbar lordosis, lumbar lordosis, spinal tilt at C7; for overall analysis: spino-sacral angle, which is an intrinsic parameter.

Meta-analysis of the effects of genetic polymorphisms on intervertebral disc degeneration

IntroductionChronic low back pain is a significant public health issue. Both its direct and indirect cost represents tens of billions of US dollars. Although chronic low back pain can be the result of many factors, the predominant cause is disc degeneration. Recent studies have shown genetic involvement in up to 74% of cases. This study aimed to evaluate genetic risk factors of disc degeneration by performing a systematic analysis of association studies. The objective is to provide a guide for practice by assessing the clinical relevance of current information.Methods and materialsWe performed a meta-analysis of 3122 items collected from 6 databases. 74 articles were selected according to our inclusion criteria. 18 (24%) could be grouped into 16 meta-analyses of 16 mutations in 12 genes. The statistics of the meta-analysis were conducted through Revman 5.1 software.ResultsThe items included are 10,250 cases and 14,136 controls. The GOLD range from 3.42 to 0.38. Two alleles were significantly associated with disc degeneration: IL-6 rs1800797 and MMP-9 rs17576 and one proved to be protective: IL-6 rs1800795. 13 meta-analyses did not yield significant results and methodological heterogeneity.DiscussionThe results highlight the lack of methodological rigor in most of the studies. The absence of international clinical and radiological classification of early disc degeneration, limits the homogeneity of studies. Understanding which populations are predisposed to this significant public health problem may change our approach to diagnostic and therapeutic methods. This work opens up enormous opportunities to provide a genetic solution and consider new diagnostic and therapeutic means to this public health problem.

Lumbar synovial cyst calcification after facet joint steroid injection.

A 57-year-old man presented symptomatic L5 right sciatica since 2 years, becoming resistant to usual analgesics. Non-contrast CT scan of the lumbar spine disclosed an intraspinal synovial cyst with the same intensity as the intervertebral disc (figure 1A, arrow). A CT-scan-guided intra-articular steroid injection was performed (one injection of 3.75 mg of cortivazol, equivalent to 62.5 mg of prednisone; figure 1B), allowing a moderate improvement of the symptomatology after 1 month. …

Polytetrafluoroethylene membrane (Gore Preclude Vessel Guard) for vessel protection during anterior lumbar surgery: a preliminary study in pigs.

Study Design The effects of implanting a polytetrafluoroethylene (PTFE) membrane (Gore Preclude Vessel Guard, WL Gore and Associates, Flagstaff, AZ) during anterior lumbar surgery were studied in a pig model. Objective We investigated whether placement of a PTFE membrane between the great vessels and anterior surface of the lumbar spine would minimize adhesions. Summary of Background Data Anterior lumbar procedures continue to increase, as do revision operations. Anterior approaches remain challenging, however, because of the considerable risk of vascular injury. The risk is especially high with revision procedures because of the presence of adhesions that can hinder visualization and mobilization of vessels. Use of an anti-adhesion barrier may decrease the rate of vascular complications associated with revision surgery. Methods Three spinal levels in 3 pigs were subjected to either discectomy, creation of a hole in the disc, or disc exposure only. In 5 of the 9 levels, a PTFE membrane was then implanted over the disc; the other 4 levels were controls. Spine segments were obtained 12 weeks later, and the tenacity of adhesions (scale of 0 to 4) and percentage of disc space covered by adhesions were assessed. The specimens were also studied histologically. Results Mean values for adhesion tenacity were 2.75 for control spinal levels and 0.4 for levels with a PTFE membrane (P=0.008). Mean values for adhesion coverage were 81% for control disc spaces and 15% for spaces with a PTFE membrane (P=0.008). Histologic studies showed minimal adhesions, lack of an inflammatory reaction, and vascularized connective tissue between PTFE membranes and the vena cava. Conclusions In a pig model, implantation of a PTFE membrane during anterior lumbar surgery decreased the tenacity and amount of adhesions observed at necropsy. Studies of the efficacy and safety of the PTFE membrane in clinical anterior lumbar surgery are warranted.

Vías de acceso de la columna vertebral torácica y de la charnela cervicotorácica

La columna vertebral toracica y la charnela cervicotoracica pueden definirse como el sector que se extiende del disco C7-T1 a T12. El conjunto de estas zonas puede verse afectado por toda la patologia vertebral: tumores, traumatismos, patologia degenerativa, deformaciones e infecciones. El tratamiento quirurgico puede estar indicado para estas distintas patologias utilizando diversas vias de acceso, que se distinguen segun su localizacion y los medios necesarios para llevarlas a cabo. En lo que respecta a la localizacion, el acceso puede ser: posterior y posterolateral en toda la region, anterolateral de T4 a T12 o anterior de C7 a T4. En lo referente a los medios, el acceso puede ser a cielo abierto o videoasistido. El conocimiento de la anatomia es una de las claves de la realizacion de estas diversas vias, lo que justifica dedicarle una resena.

Tratamiento quirúrgico de la espondilolistesis por lisis ístmica. Niño y adulto

La espondilolistesis por lisis istmica es una patologia que hay que diferenciar de la etiologia degenerativa. La espondilolistesis por lisis istmica apareceria durante la verticalizacion de la marcha y esta presente en el nino y en el adulto. Su tratamiento es complejo y requiere un estudio completo para identificar los diferentes tipos de equilibrio sagital. La estrategia terapeutica debe integrar diversos factores clinicos asi como radiologicos. Las soluciones terapeuticas pueden ser multiples, conservadoras o quirurgicas. La reduccion de la espondilolistesis no es siempre necesaria, aunque el elemento esencial es respetar un equilibrio sagital economico.

New Composite Material: PLLA and Tricalcium Phosphate for Orthopaedic Applications-In Vitro and In Vivo Studies (Part 1)

This study showed that adding increasing percentages of β–TCP to a lactic acid polymer matrix stimulated the proliferation of human osteogenous cells and synthesis of the extra-cellular bone matrix in a dose-dependent manner. In vivo results indicate that, in comparison with pure PLA, tricalcium phosphate-containing composite materials had faster degradation kinetics, caused less inflammatory reaction, and promoted contact osteogenesis. The composite material containing 60 % β-ʿTCP demonstrated a similar performance to pure tricalcium phosphate bone grafts in terms of osteogenesis and is apparently compatible with the production of intra-osseous implants for obtaining bone fusion or healing. Further studies are necessary to evaluate the ability of such a composite material to retain sufficient mechanical strength overtime for providing safe correction or stabilization of the implanted bone fragments.

Surgical Treatment of Lumbar Spondylolisthesis Due to Isthmic Lysis

Spondylolysis is a unilateral or bilateral defect of the isthmus (pars interarticularis) located between the superior articular process and inferior articular process of a vertebral body (Fig. 35.1).

Clinical Results of a New Resorbable Composite Material for Cervical Cage: 6 Years’ Follow-up (Part 2)

Efficiency of corticocancellous autologous bone grafts in cervical interbody fusion has been widely reported since Smith and Robinson or Cloward. Depending on the studies, 70–96 % of the patients develop good or excellent results. However, the use of autologous grafts induces a second operation, generally on the iliac crest, and may be associated with an important morbidity. Moreover, such complications as long term pain syndrome, femorocutaneus nerve damage, infection or secondary fracture has been reported. In order to prevent such risks, different bone substitutes are nowadays available. Natural ones like allografts or xenografts have been studied since decades. With a cancellous-like architecture, their macroscopical structure can help bone ingrowth and lead to satisfying results with regards to bone fusion, both on animal models or humans. But these natural bone grafts still represent a microbiological risk, like AIDS, hepatitis or non-conventional disease transmission. For these reasons, we preferred synthetic materials when choosing a bone substitute. Elaborated from pure chemical compounds, such materials seemed safer to us. Among the family of synthetic materials, calcium phosphate compounds like hydroxylapatite (HA) are probably better known. Intensively studied over the last 20 years, such compounds are biocompatible. In a porous form, they facilitate bone cells penetration and lead, as well as allografts or heterografts, to bone healing and fusion with surrounding bone.

Report of One Year Follow Up of Patients after TLIF using a 3-Dimensional Expandable Cage for Lumbar Fusion with Lordotic Correction

Introduction The use of a new 3 dimensional (3D) expandable cage for TLIF was extensively studied in biomechanical tests, cadaver specimens and preliminary clinical series. A wide footprint is achieved through a one side portal due to the articulated implant positioned in the anterior third of the disc space. The lordotic correction is accomplished due to the expansion of the device in place assisting on the overall sagittal alignment. Previous reports presented showed initial promising clinical results. One year follow up of the first 10 patients is now reported. Material and Methods Ten patients were included in a 12 months prospective review after a TLIF using a 3D Titanium alloy FLXFit expandable cage. The procedure was done for a single or two level fusion with positioning of the cage under fluoroscopy and expansion for disc space height and lordotic correction. All patients were supplemented with posterior instrumentation. Primary clinical outcomes were evaluated by preoperative, 6 months, 12 months and last follow-up visual analog scale (VAS) and the Oswestry Disability Index (ODI) scores. Complications and neurological impairment were recorded. Radiographic assessment of pre and post-operative results was performed with measurement of correction achieved in the frontal and sagittal planes with EOS imaging technology avoiding any distortion on X-Rays. All patients underwent CT scan control at 12 months. Results All ten patients underwent a successful one or two levels instrumented TLIF without any permanent neurological, vascular or visceral complication. The 3D cage implantation provided lordosis augmentation of 8° (± 2.1°) allowing restoration of the sagittal alignment according to pre-op planning. On early post-op CT scans, good footprint and no endplate violation were shown with no cage subsidence. Clinical outcomes showed significant improvement for both VAS and Oswestry scores (P < 0.05), 3.7 (± 2.9) and 31% (±11) respectively. Similar outcomes were found at 12 months: no cage subsidence, VAS and Oswestry scores (P < 0.05), 3.5 (± 2.7) and 28,4% (±12) respectively. Conclusion Lumbar interbody fusion using this new 3D expandable cage provided correction of the lordosis in a shorter and effective surgical procedure. A wide footprint well positioned cage, with customized height and angular correction achievement assured an optimal load transmission and biomechanical environment for fusion. Initial clinical results were followed with successful clinical outcomes in all patients.