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Data on elite gymnast injuries outside North America is sparse. We report the injuries recorded over a period of 10 years in 156 Greek elite male and female gymnasts. A total of 2390 injuries were reported for a rate of 1,5 new injuries per year per athlete. Most commonly affected areas were the hip (18.5%), the ankle (16.5%), the lumbar spine (16%) and the foot (16%). The most frequent diagnosis was tendinitis (32%), followed by low back pain (20%), and sprains (12%). Fifteen athletes (9%) sustained serious injuries that required surgery. Rhythmic gymnasts had significantly more overuse type injuries compared to artistic gymnasts (p = 0.049). Gymnastics is a sport with a high incidence of musculoskeletal pathology that needs proper documentation in order to establish preventive measures.
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Traumatismos em Atletas/epidemiologia , Ginástica/lesões , Sistema Musculoesquelético/lesões , Adolescente , Adulto , Atletas , Feminino , Grécia/epidemiologia , Humanos , Incidência , Dor Lombar/epidemiologia , Masculino , Entorses e Distensões/epidemiologia , Tendinopatia/epidemiologia , Adulto JovemRESUMO
Neglected patella non-unions are rare. Contraction of the quadriceps makes late repair extremely difficult. A case of distal patella pole fracture neglected for 8 years is presented. The patient was a hemiplegic young female unable to walk due to extensor mechanism deficiency with a 10 cm retraction of the patella proximal pole at her neurologically intact side. The quadriceps was lengthened using a spanning unilateral external fixation system and the fragments successfully united after trans-osseous suture repair. At 4-year follow-up the patient was independently ambulating without symptoms with a functional knee range of motion. Level of evidence IV.
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Fraturas não Consolidadas/cirurgia , Equipamentos Ortopédicos , Patela/cirurgia , Músculo Quadríceps/cirurgia , Adulto , Feminino , Humanos , Articulação do Joelho/cirurgia , Amplitude de Movimento Articular , Procedimentos de Cirurgia Plástica , SuturasRESUMO
PURPOSE: Acute Achilles tendon tears in young active individuals are often treated surgically with prolonged rehabilitation, with the leg initially immobilized in plantar flexion in serial non-weight bearing casts and gradually progressing to full weight bearing. This study aimed to evaluate the safety of an early functional unsupervised rehabilitation protocol. METHODS: The medical records of 25 patients treated with open repair were available for follow-up. In 10 patients, an early functional unsupervised rehabilitation protocol was used with a removable cast, active range of motion exercises of the ankle from the first postoperative day, and full weight bearing in a walking boot with the foot plantigrade after the second week. Another 15 patients who followed the classic rehabilitation protocol were used as controls. The patients were evaluated with the Victorian Institute of Sports Assessment-Achilles (VISA-A) and an ultrasound examination-based score. A Wilcoxon test was used to compare the scores between the groups. RESULTS: The mean VISA-A score was 90.1 (SD = 9.87) for the early functional rehabilitation protocol group, while it was 83.8 (SD = 17.06, p = 0.624) for the control group. The mean ultrasound score was 7.75 (SD = 1.71) for the early functional rehabilitation protocol group, while it was 7.60 (SD = 3.05, p = 0.414) for the control group. There were no intra- or early postoperative complications in the groups, and all patients were satisfied with the results of their operation. CONCLUSIONS: An early unsupervised functional rehabilitation protocol after open Achilles repair may allow for safe early mobilization and minimize the need for physiotherapy. The small number of participants is a limitation of this study, and further evaluation with more patients is necessary to document the efficacy.
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We present a rare case of delayed femoral nerve palsy resulting from a pseudo-aneurysm presenting as excruciating anterior thigh pain 2 months after an uneventful total hip arthroplasty through a Watson Jones approach. The large pseudo-aneurysm of the posterior wall of the femoral artery was treated with open exploration and artery repair since the anatomy of the lesion precluded an embolization. Although pain resolved immediately, the recovery of the femoral nerve started after 3 months, while full quadriceps function was restored by the 6th month. Positioning a Hohmann retractor along the inferior part of the anterior acetabulum rim may place the femoral artery branches under significant stretch. Preserving the capsule and keeping the retractor tension as low as possible may avoid this complication.
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INTRODUCTION: In-flight medical events (IMEs), although rare, are challenging due to the limited onboard resources and the time needed to reach an airport. Cabin crewmembers (CCMs) are trained to provide first aid, but their effectiveness has not been appropriately studied.METHODS: IMEs occurring in the biggest airline of Greece were prospectively recorded during a 5-yr period (20142018) and categorized according to a symptom-based taxonomy.RESULTS: During the study period 990 IMEs were recorded corresponding to 16 IMEs for each million passengers or 1.8 IMEs for every thousand flights. The most frequent events were loss of consciousness (38.4%) followed by injuries (8.6%), gastrointestinal problems (8.3%), respiratory symptoms (7.3%), anxiety (5.7%), and burns (5.9%). Diversion was decided in 3% of the cases while death on board was rare (0.3% of events). CCMs responded in 33.5% of IMEs without assistance by a volunteer health professional, achieving a 97% success rate.DISCUSSION: IMEs are rare events and the majority can be treated with simple first aid measures. CCMs acting according to a simplified algorithm were very efficient in providing first aid. A standardized symptom-based IME form will assist in creating a reliable registry for further studies.Paxinos O, Savourdos P, Alexelis V, Anastasopoulos A, Karantoni E, Grigoropoulos P, Konstantinou X. In-flight medical events and cabin crew first aid response. Aerosp Med Hum Perform. 2021; 92(1):3238.
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Primeiros Socorros , Voluntários , Aeronaves , HumanosRESUMO
BACKGROUND: The gold-standard treatment for intra-articular distal humerus fractures (DHFs) is dual-plate/dual-column fixation, though optimal orientation is not yet established. With a superior method not yet identified, we propose a load-sharing construct, combining absolute stability (extramedullary plate fixation) for distal articular fragments and relative stability (load-sharing intramedullary nail) for the metaphyseal segment. The purpose of this pilot study was to evaluate the biomechanical performance of a novel implant compared to orthogonal dual-plating. MATERIALS AND METHODS: Ten fresh-frozen matched-pairs of human cadaveric upper extremities with no prior elbow pathology/surgery were used. Pairs were randomized into two groups: Dual-Plate (medial and posterolateral) or novel Nail/Plate (cross-locked medial nail and posterolateral plate). AO/ASIF type 13-C2.3 multifragmentary fractures with simulated metaphyseal comminution. Biomechanical testing included stiffness (MPa) and load to failure (Newtons) in axial (100 cycles at 3 Hz at 20 N increments from 20 to 100 N) and coronal (varus/valgus; 4,000 cycles from 50N-100 N at 3 Hz) planes. Failed specimens were not analyzed and mechanisms were identified. For all failures, mechanisms were identified and reviewed by three consultant surgeons for revision vs. immobilization, to attempt to recreate a real-world scenario. All outcomes were compared between groups. RESULTS: During stiffness testing, zero Nail/Plate specimens failed, but two (20%) Dual-Plate specimens failed (mechanisms: fracture diastasis; bone collapse and intussusception into osteotomy, yielding articular congruency loss). For remaining samples, Nail/Plate (n = 10) coronal (varus/valgus) stiffness was comparable to Dual-Plate (n = 8) constructs (41.5 vs. 39.0 MPa, p = 0.440). Remaining Dual-Plate constructs had greater axial overall stiffness than Nail/Plate (118.3 ± 48.3 vs. 95.6 ± 34.7 MPa, p = 0.020). Failure loads were comparable between Nail/Plate and Dual-Plate constructs (1,327.8 vs. 1,032.4 N, p = 0.170). Individual nail yield strength ranged from 1,101.1-1,124.4 N (n = 2). In review of all failures, the most common overall mechanism was fracture/osteotomy site posterolateral plate bending. Revision recommendation rate was comparable between constructs (Nail/Plate, 22.2% vs. Dual-Plate, 44.4%, p>0.05). CONCLUSIONS: The novel Nail/Plate construct demonstrated non-inferior coronal (varus/valgus) stiffness, despite producing lower axial stiffness than orthogonal dual-plating, potentially due to the load-sharing cross-locked design. Considering comparable biomechanical performance, with no failures and comparable recommendations for revision, this novel construct warrants further evaluation as an alternative to the gold-standard, dual-plate fixation method for intra-articular distal humerus fractures. LEVEL OF EVIDENCE: N/A.
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Placas Ósseas , Fraturas Intra-Articulares , Fenômenos Biomecânicos , Cadáver , Fixação Interna de Fraturas , Humanos , Úmero , Projetos PilotoRESUMO
The exact pathophysiology of osteonecrosis of the femoral head (ONFH) is still unknown. There is evidence to suggest that in ON there is decreased population and altered function of the mesenchymal stem cells (MSCs) of the femoral head. This could influence both the actual occurrence of ON itself and the repair process that follows. Hence, in such an environment it only is rational to consider the use of cell-based treatments to potentially regenerate lost or damaged bone. The aim of this review is to provide an up-to-date, evidence-based information in the use of cell therapies in the treatment of nontraumatic ONFH and the use of hip arthroscopy in the field.
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BACKGROUND: Although knee injuries in professional soccer (football) have been extensively studied, the prevalence of knee osteoarthritis (OA) in veteran players is not well documented. PURPOSE: To investigate the prevalence of knee OA in retired professional soccer players in comparison with a group of athletically active military personnel. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A group of 100 veteran Greek soccer players aged 35 to 55 years (mean [±SD] age, 46.90 ± 5.9 years) were examined for knee OA and were administered the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire. A matched group of 100 athletically active military personnel served as a comparison group. RESULTS: The sonographic prevalence of OA was significantly higher in the veteran soccer group (52%) than in the military group (33%) (n = 200; P = .010). This difference remained significant even after excluding participants with a history of knee surgery (44.1% vs 25.3%, respectively) (n = 151; P = .010). Femoral cartilage thickness was similar between the 2 groups (P = .473), while altered knee alignment had no effect on the prevalence of OA (P = .740). With the exception of perceived pain being more prevalent in the military group, there were no other statistically significant differences between the 2 groups in KOOS values. CONCLUSION: Veteran soccer players had a higher sonographic prevalence of knee OA but better pain scores than a matched group of athletically active military personnel.
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Atletas , Militares , Osteoartrite do Joelho/epidemiologia , Futebol/lesões , Adulto , Atletas/estatística & dados numéricos , Estudos Transversais , Grécia/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Militares/estatística & dados numéricos , Osteoartrite do Joelho/etiologia , Prevalência , AposentadoriaRESUMO
BACKGROUND: Fatigue fractures of the tibia have been observed at the level of the proximal end of the nail after successful tibiocalcaneal arthrodesis with a retrograde intramedullary device. MATERIALS: To study the effect of nail length, five matched pairs of cadaver tibiae were instrumented with strain gauges and potted in methylmethacrylate from a level 3 cm proximal to the distal medial malleolus to simulate a successful tibiocalcaneal arthrodesis. A standard length (15 cm) ankle arthrodesis nail and an identical longer device terminating in the proximal tibial metaphysis were inserted in each paired tibia using appropriate technique. The strain of the posterior cortex of the tibia was recorded under bending moments of up to 50 Nm for each intact specimen after nail insertion and after proximal locking of the nail. The nails were then exchanged between the specimens of the same pairs and the experiment was repeated to insure uniformity. RESULTS: The standard length locked nail increased the principal strain of the posterior cortex of the tibia at the level of the proximal screw holes 5.3 times more than the locked long nail (353 and 67 microstrains), respectively. This stress concentration was not observed when the proximal extent of the nail terminated within the proximal tibial metaphysis. CONCLUSION: A successful tibiocalcaneal arthrodesis with a standard length locked intramedullary nail creates stress concentration around the proximal screw holes that may be responsible for the fractures observed clinically. This study supports the use of a "long" retrograde locked intramedullary nail for tibiocalcaneal arthrodesis in patients with systemic or localized osteopenia.
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Articulação do Tornozelo/cirurgia , Artrodese/instrumentação , Pinos Ortopédicos/normas , Fraturas de Estresse/etiologia , Idoso , Pinos Ortopédicos/efeitos adversos , Cadáver , Calcâneo/cirurgia , Feminino , Humanos , Masculino , Estresse Mecânico , Tíbia/cirurgia , Fraturas da Tíbia/etiologia , Fraturas da Tíbia/fisiopatologiaRESUMO
Iatrogenic aortic injuries are rare and well-recognized complications of a variety of procedures, including spinal surgery. The placement of pedicle screws is sometimes associated with devastating consequences. Aortic perforation with rapid hematoma formation and delayed aortic trauma leading to pseudoaneurysm formation have been described in the literature. A case describing a significant time interval between iatrogenic aortic injury and diagnosis in the absence of pseudoaneurysm formation is described in this paper and, according to our knowledge, is unique in the literature. The aortic injury was successfully treated, selecting the appropriate graft and, as a consequence, normal spinal cord blood flow was achieved.
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Traditional experimental methods are unable to study the kinematics of whole lumbar spine specimens under physiologic compressive preloads because the spine without active musculature buckles under just 120 N of vertical load. However, the lumbar spine can support a compressive load of physiologic magnitude (up to 1200 N) without collapsing if the load is applied along a follower load path. This study tested the hypothesis that the load-displacement response of the lumbar spine in flexion-extension is affected by the magnitude of the follower preload and the follower preload path. Twenty-one fresh human cadaveric lumbar spines were tested in flexion-extension under increasing compressive follower preload applied along two distinctly different optimized preload paths. The first (neutral) preload path was considered optimum if the specimen underwent the least angular change in its lordosis when the full range of preload (0-1200 N) was applied in its neutral posture. The second (flexed) preload path was optimized for an intermediate specimen posture between neutral and full flexion. A twofold increase in flexion stiffness occurred around the neutral posture as the preload was increased from 0 to 1200 N. The preload magnitude (400 N and larger) significantly affected the range of motion (ROM), with a 25% decrease at 1200 N preload applied along the neutral path. When the preload was applied along a path optimized for an intermediate forward-flexed posture, only a 15% decrease in ROM occurred at 1200 N. The results demonstrate that whole lumbar spine specimens can be subjected to compressive follower preloads of in vivo magnitudes while allowing physiologic mobility under flexion-extension moments. The optimized follower preload provides a method to simulate the resultant vector of the muscles that allow the spine to support physiologic compressive loads induced during flexion-extension activities.
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Força Compressiva/fisiologia , Vértebras Lombares/fisiologia , Modelos Biológicos , Movimento/fisiologia , Adulto , Idoso , Fenômenos Biomecânicos , Feminino , Humanos , Técnicas In Vitro , Masculino , Pessoa de Meia-IdadeRESUMO
OBJECTIVE: To present the treatment method and outcome of 5 cases of type IV coronal shear fractures of the distal end of the humerus. DESIGN: Retrospective study. PATIENTS: Five patients with an isolated type IV coronal shear fracture of the distal end of the humerus. INTERVENTION: Open reduction and internal fixation of the fractures utilizing Herbert screws, through a modified extensile lateral Kocher approach. MAIN OUTCOME MEASUREMENTS: Functional elbow index rating scale of Broberg-Morrey, Mayo Elbow Performance Score, subjective satisfaction rate and subjective functional limitations, and radiographic evaluation of the operated elbows for the presence or absence of osteonecrosis and degenerative joint disease changes. RESULTS: The follow-up time ranged from 39 to 50 months. All fractures healed within 6 to 9 weeks. The latest radiographic evaluation revealed mild degenerative joint disease changes in 1 patient and osteonecrosis of the coronal shear fragment in another. None of the patients reported pain even during strenuous activities, and none had clinical findings or subjective complaints suggesting instability of the elbow joint. Four patients regained full range of elbow motion compared with the contralateral elbow, and only 1 had a 10 degrees extension lag. The muscle strength of the major muscle groups of the operated elbow was equal to that of the uninjured elbow when tested clinically. No patient reported limitations in activities, and all indicated complete satisfaction with their outcome. According to the Broberg-Morrey scale and the Mayo Elbow Performance Score, all results were excellent, with scores ranging from 98 to 100 points. CONCLUSIONS: Recognition of this particular type of injury, prompt treatment with anatomic reduction and internal fixation, and early rehabilitation can lead to excellent functional outcomes.
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Fixação Interna de Fraturas , Fraturas do Úmero/fisiopatologia , Fraturas do Úmero/cirurgia , Recuperação de Função Fisiológica/fisiologia , Adulto , Parafusos Ósseos , Feminino , Seguimentos , Humanos , Fraturas do Úmero/diagnóstico por imagem , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde , Radiografia , Estudos Retrospectivos , Resistência ao Cisalhamento , Índices de Gravidade do TraumaRESUMO
Progressive spondylolisthesis may occur in adults with isthmic spondylolysis with an estimated incidence of 20%. This biomechanical study showed that in adult spines with bilateral L5 pars fractures, an anterior slip of L5 depends on the extent of the load-bearing deficiency of the disc and the presence of shear force across L5-S1. A combination of disc degeneration and muscle dysfunction may be responsible for converting a stable isthmic spondylolysis into an unstable progressive spondylolisthesis.
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Vértebras Lombares/fisiopatologia , Espondilolistese/fisiopatologia , Adulto , Força Compressiva/fisiologia , Progressão da Doença , Lateralidade Funcional/fisiologia , Humanos , Disco Intervertebral/fisiopatologia , Fatores de Risco , Sacro/fisiopatologia , Resistência ao Cisalhamento , Fraturas da Coluna Vertebral/fisiopatologia , Suporte de Carga/fisiologiaRESUMO
We report the case of a 16-year-old elite gymnast who presented with recurring pain in the left shoulder after training. The athlete recalled an injury to the shoulder 2 years ago. Clinically a localized tenderness to the anterior shoulder and loss of strength and range of motion was noted. Imaging investigation suggested a neglected lesser tuberosity avulsion. The athlete was treated with open excision of the deformed tuberosity and direct repair of the subscapularis to the humeral head. Following a careful postoperative rehabilitation protocol the athlete was able to return to unrestricted gymnastics after 6 months. After surgery the athlete followed a intense rehabilitation program that allowed him to return to sports at 6 months. At 5-years follow-up, the athlete was asymptomatic and competing at an international level. Avulsion fractures of the lesser tuberosity are extremely rare injuries with significant shoulder disability if left untreated. Anatomic repair can yield excellent results, even in neglected cases.
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OBJECT: There is limited data on the pullout strength of spinal fixation devices in the thoracic spine among individuals with different bone quality. An in vitro biomechanical study on the thoracic spine was performed to compare the pullout strength and the mechanism of failure of 4 posterior fixation thoracic constructs in relation to bone mineral density (BMD). METHODS: A total of 80 vertebrae from 11 fresh-frozen thoracic spines (T2-12) were used. Based on the results from peripheral quantitative CT, specimens were divided into 2 groups (normal and osteopenic) according to their BMD. They were then randomly assigned to 1 of 4 different instrumentation systems (sublaminar wires, pedicle screws, lamina claw hooks, or pedicle screws with wires). The construct was completed with 2 titanium rods and 2 transverse connectors, creating a stable frame. The pullout force to failure perpendicular to the rods as well as the pattern of fixation failure was recorded. RESULTS: Mean pullout force in the osteopenic Group A (36 vertebrae) was 473.2 ± 179.2 N and in the normal BMD Group B (44 vertebrae) was 1414.5 ± 554.8 N. In Group A, no significant difference in pullout strength was encountered among the different implants (p = 0.96). In Group B, the hook system failed because of dislocation with significantly less force than the other 3 constructs (931.9 ± 345.1 N vs an average of 1538.6 ± 532.7 N; p = 0.02). In the osteopenic group, larger screws demonstrated greater resistance to pullout (p = 0.011). The most common failure mechanism in both groups was through pedicle base fracture. CONCLUSIONS: Bone quality is an important factor that influences stability of posterior thoracic implants. Fixation strength in the osteopenic group was one-fourth of the value measured in vertebrae with good bone quality, irrespective of the instrumentation used. However, in normal bone quality vertebrae, the lamina hook claw system dislocated with significantly less force when compared with other spinal implants. Further studies are needed to investigate the impact of different transpedicular screw designs on the pullout strength in normal and osteopenic thoracic spines.
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Doenças Ósseas Metabólicas/cirurgia , Teste de Materiais , Dispositivos de Fixação Ortopédica , Procedimentos Ortopédicos , Vértebras Torácicas/cirurgia , Fenômenos Biomecânicos , Densidade Óssea , Doenças Ósseas Metabólicas/patologia , Pinos Ortopédicos , Placas Ósseas , Parafusos Ósseos , Fios Ortopédicos , Desenho de Equipamento , Falha de Equipamento , Humanos , Técnicas In Vitro , Teste de Materiais/instrumentação , Dispositivos de Fixação Ortopédica/efeitos adversos , Radiografia , Fraturas da Coluna Vertebral/diagnóstico por imagem , Fraturas da Coluna Vertebral/cirurgia , Vértebras Torácicas/diagnóstico por imagem , TitânioRESUMO
STUDY DESIGN: An in vitro three-dimensional (3D) flexibility test of human C3-C7 cervical spine specimens. OBJECTIVE: To test the hypothesis that anterior cervical fusion with a wedged graft and a locked plate can effectively stabilize the cervical spine after complete anterior and posterior segmental ligamentous release. SUMMARY OF BACKGROUND DATA: Distraction-flexion Stage 3 injuries of the lower cervical spine (bilateral facet dislocations) are usually reduced under awake cranial traction. When the magnetic resonance imaging reveals a traumatic disc prolapse, anterior cervical discectomy and fusion (ACDF) is usually recommended. Most authors advise combining ACDF with posterior instrumentation to address the insufficiency of the posterior elements. However, there is clinical evidence that ACDF with a locked plate alone suffices for the treatment of these injuries, especially in young patients. Still, there are no biomechanical studies on the effect of a locked plate on the complete anterior and posterior ligamentous-deficient young cervical spine under physiologic preload. METHODS: Eight fresh frozen human lower cervical spines (C3-C7) from young donors (age, 44.5 years; range, 21-63 years) were used. A 3D flexibility test was conducted using a moment of 0.8 Nm without preload. Flexion-extension was additionally tested using a moment of 1.5 Nm under 0 and 150 N follower preload. Spines were tested first intact, then after complete C5-C6 discectomy with posterior longitudinal ligament resection and ACDF with a wedged bone graft and a rigid locked plate, and finally after complete release of the supraspinous, interspinous, and intertransverse ligaments; the facet capsules; and ligamentum flavum. RESULTS.: When tested under 0.8 Nm moment without preload, complete posterior and anterior ligamentous release did not significantly increase the ROM of the ACDF construct in flexion-extension (P > 0.025), lateral bending (P > 0.025), and axial rotation (P > 0.025). When tested under 1.5 Nm moment with or without a compressive preload, the complete posterior and anterior ligamentous release did not significantly affect the ROM of the ACDF construct (P > 0.01). The application of preload significantly reduced the motion at the C5-C6 ACDF construct with ligamentous disruption in comparison with the motion in the absence of a preload (P < 0.01). CONCLUSION: Anterior cervical fusion with a wedged graft and a rigid constrained (locked) plate can effectively stabilize the nonosteoporotic cervical spine after complete posterior element injury when excessive ROM is prevented (for example, by the use of postoperative external immobilization). Even when the construct is subjected to higher moments, adequate stability can be achieved when physiologic preload is present. Osteoporosis and lack of sufficient preload due to poor neuromuscular control may affect long-term screw stability, and additional external immobilization may be needed until fusion matures.
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Placas Ósseas , Transplante Ósseo/métodos , Vértebras Cervicais/cirurgia , Discotomia/métodos , Amplitude de Movimento Articular , Fusão Vertebral/métodos , Traumatismos da Coluna Vertebral/cirurgia , Adulto , Fenômenos Biomecânicos , Densidade Óssea , Discotomia/instrumentação , Humanos , Masculino , Pessoa de Meia-Idade , Fusão Vertebral/instrumentaçãoRESUMO
STUDY DESIGN: The authors conducted an in vitro biomechanical flexibility study of T2-S1 specimens in flexion-extension under compressive follower preloads of physiological magnitudes. OBJECTIVES: The objectives of this study were to test the hypotheses that 1) the thoracolumbar spine will support compressive preloads of in vivo magnitudes and 2) allow physiological mobility under flexion-extension moments if the preload is applied along an optimized follower load path that approximates the kypholordotic curve of the thoracolumbar spine. SUMMARY OF BACKGROUND DATA: In the absence of muscle forces, the ligamentous thoracolumbar spine specimens cannot support the compressive loads expected in vivo. As a result, the flexibility of the thoracolumbar spine in flexion-extension has not been studied in vitro under physiological compressive preloads. METHODS: Seven human thoracolumbar spines (T2-sacrum) were subjected to flexion and extension moments (up to 8 and 6 Nm, respectively) under compressive preloads from 0 to 800 N applied along an optimized follower preload path. The experimental technique applied the compressive preload such that: 1) it minimized the internal shear forces and bending moments resulting from the preload application, 2) made the internal force resultant compressive, and 3) caused the preload path to approximate the tangent to the curve of the thoracolumbar spine. The range of motion was measured in the T2-sacrum, T2-T11, T11-L1, and L1-sacrum regions. RESULTS: All thoracolumbar specimens supported the compressive follower preload up to 800 N without damage or instability. At 800 N preload, the total flexion-extension range of motion of the T2-sacrum region decreased by 22%, from a mean of 73 degrees to 57 degrees (P < 0.05). The range of motion of the T2-T11 and L1-sacrum regions decreased from the baseline value by 23% and 30%, respectively, at a preload of 800 N. The sagittal mobility of the thoracolumbar junction (T11-L1) was not affected by the preload. The follower preload did not significantly affect the proportion of the total T2-sacrum flexion-extension range of motion contributed by the T2-T11 and L1-sacrum regions of the thoracolumbar spine. CONCLUSIONS: The optimized follower preload vector minimizes the effects of artifact moment and shear force on the range of motion of the thoracolumbar spine in flexion-extension. This model allows the entire thoracolumbar spine to be investigated under physiological loading for different clinical applications.