Interspinous distraction in lumbar spinal stenosis: a neurophysiological perspective.

STUDY DESIGN: Prospective neurophysiological study. OBJECTIVE: To identify and quantify the neurophysiological effects of interspinous distraction during spine surgery for lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA: Interspinous devices have been introduced as an alternative treatment of LSS in selected patients aiming at obtaining indirect decompression. Nevertheless, there is no data on the immediate neurophysiological effect of distraction. METHODS: Thirty patients with LSS undergoing decompression (14 at single level, 16 at multiple levels) were enrolled, resulting in a total of 48 levels to be analyzed. Before decompression, calibrated incremental distraction simulating interspinous device implantation of 8, 10, 12, 14, and 16 mm was performed. Intraoperative motor evoked potentials were acquired before any distraction, during distraction at each incremental value and after bilateral decompression. We evaluated relative changes of motor evoked potentials normalized to hand muscles and related them to the number of affected levels, LSS radiological severity based on the A to D grading, lordosis, and disc height. RESULTS: For single-level disease, 8-mm distraction and open decompression yielded similar improvement in motor evoked potentials not only in levels with morphological grades A or B, but also in levels with morphological grades C or D (i.e., severe or extreme stenosis) (P = 0.32). In contrast, distraction superior to 8 mm was less effective (P ≤ 0.05). In multiple-level stenosis, decompression was significantly more effective than any degree of distraction (P < 0.001). No correlation of those results to disc height or lordosis was observed. Using χ trend test to analyze the effect of distraction, a linear trend favoring moderate over severe stenotic morphology was observed (P = 0.0349). CONCLUSION: Interspinous distraction of 8 mm is sufficient to replicate electrophysiological improvements obtained during full decompression even in severe single-level stenosis but not in multilevel disease. Interspinous distraction has therefore an immediately measurable neurophysiological effect. LEVEL OF EVIDENCE: 4.

Cerebral fat emboli: a trigger of post-operative delirium.

Accumulating evidence implicates cerebral fat embolism (CFE) as a causative agent in post-operative confusion (POC). CFE occurs following orthopaedic procedures including, intra-medullary (IM) nailing and total joint arthroplasty (TJA). The incidence of CFE is high (59-100% TJA) and the resulting POC is associated with higher overall complication rates. Cognitive dysfunction improves in many patients but can persist - with potentially disastrous outcomes. The pathomechanics of CFE implicate circulating lipid micro-emboli (LME) that are forced from IM depots by instrumentation/nailing. Passage to the left side of the heart is possible through intra-cardiac or arteriovenous shunts in the lung. LME are propelled to the brain where they cause disruption via ischemia or by alterations in the blood-brain-barrier - causing cerebral oedema. Prevention of CFE follows established practices for preventing FES and consideration of additional techniques to remove resident fat and reduce IM pressures. When CFE occurs supportive treatment should be established.

Revision of a nonunited subtrochanteric femoral fracture around a failed intramedullary nail with the use of RIA products, BMP-7 and hydroxyapatite: a case report.

INTRODUCTION: Femoral subtrochanteric fractures are commonly treated using intramedullary devices. Failure of the implant and subsequent nonunion is still an issue, however, and limited evidence exists regarding the most appropriate treatment. CASE PRESENTATION: We report the case of an 80-year-old Caucasian woman with a subtrochanteric fracture originally treated using a trochanteric gamma nail which failed, resulting in a nonunion and fracture of its proximal end. The nonunion was revised with the removal of the broken trochanteric gamma nail, application of a condylar blade plate, ipsilateral Reamer/Irrigator/Aspirator autografting, recombinant human bone morphogenetic protein-7 and injectable hydroxyapatite cement. The fracture united fully at ten months following revision surgery, with no signs of femoral head avascular necrosis at 18-month follow-up. CONCLUSION: The essential requirements for success when revising a nonunited fracture are to provide anatomical reduction, mechanical stability, bone defect augmentation and biological stimulation to achieve healing. Current advances in molecular biology, such as recombinant human bone morphogenetic protein-7, and biotechnology such as the Reamer/Irrigator/Aspirator system and hydroxyapatite injectable cement can improve patient outcomes over the use of our traditional revision techniques.

Timing of fracture fixation in multitrauma patients: the role of early total care and damage control surgery.

The optimal timing of surgical stabilization of fractures in the multitrauma patient is controversial. There are advantages to early definitive surgery for most patients. Early temporary fixation using external fixators, followed by definitive fixation (ie, the damage control approach), may increase the chance for survival in a subset of patients with severe multisystem injuries. Improved understanding of the pathophysiology of trauma has led to a greater ability to identify patients who would benefit from damage control surgery. A patient is classified as physiologically stable, unstable, borderline, or in extremis. The stable patient can undergo fracture surgery as necessary. An unstable patient should be resuscitated and adequately stabilized before receiving definitive orthopaedic care. The decision whether to perform initial temporary or definitive fixation in the borderline patient is individualized based on the clinical condition. In patients presenting in extremis, life-saving measures are pivotal, followed by a damage control approach to their injuries.

Local exposure of bone components to injured soft tissue induces Toll-like receptor 4-dependent systemic inflammation with acute lung injury.

Remote and systemic inflammatory responses after long bone fractures have been well described, but the mechanisms underlying these changes remain unexplained. We hypothesized that bone components locally exposed to injured soft tissue are capable of inducing a systemic inflammatory response associated with acute lung injury, and that this inflammatory cascade requires Toll-like receptor 4 (TLR-4) signaling. Accordingly, male C3H/HeOuJ (TLR-4-competent) and C3H/HeJ (TLR-4-mutant) mice were injected with various bone components (bone marrow cells, bone marrow supernatant, and bone suspension, respectively) in bilaterally injured thigh muscles and euthanized after 6 h. Serum TNF-alpha, IL-6, and IL-10 levels, and pulmonary myeloperoxidase activity was measured using specific enzyme-linked immunosorbent assay kits. Pulmonary permeability changes were assessed with bronchoalveolar lavage. Local exposure of bone components to injured soft tissue induced systemic inflammation and acute lung injury in TLR-4-competent, but not in TLR-4-mutant, animals. These findings suggest that bone components contribute to systemic inflammation and acute lung injury after long bone fractures via TLR-4 signaling and support the notion of a central role for TLR-4 in sensing tissue damage.

Prevalence of pelvic fractures, associated injuries, and mortality: the United Kingdom perspective.

BACKGROUND: We wished to determine the characteristics of patients with pelvic ring fractures (PGs) in England and Wales, make comparisons to major trauma patients without pelvic injury (NPGs), and determine factors predicting mortality, including the impact of presence of pelvic reconstruction facilities in the receiving hospitals on outcome. METHODS: Prospective data from 106 trauma receiving hospitals forming the Trauma Audit and Research Network were studied. Between January 1989 and December 2001 data of 159,746 trauma patients were collected in the Trauma Audit and Research Network database. Because of incomplete data, 1,610 pelvic fracture patients and 13,499 patients without pelvic fracture were excluded from detailed analysis. In total, 11,149 patients in the PG and the remaining 133,486 patients in the NPG (control) group were included in the final analysis. RESULTS: There were statistically significantly more patients with an Injury Severity Score >15 in the PG group (n = 3,576; 32.1%) than in NPG group (n = 19,238; 14.4%) (p < 0.001), indicating that pelvic injuries were more often associated with other injuries. The majority of patients sustained Abbreviated Injury Score (AIS) 2 pelvic injuries (65.0%), whereas AIS 4 and 5 injuries were found in less than 10% of patients. Pelvic ring injuries were most commonly associated with chest trauma with >AIS 2 severity in 21.2% of the patients, head injuries (>AIS 2) in 16.9%, liver or spleen injuries in 8.0%, and two or more long bone fractures in 7.8%. The 3-month cumulative mortality rate of the patients with pelvic injuries was 14.2% (1,586 patients) versus 5.6% (7,465 patients) of the NPG group. CONCLUSION: Age, early physiologic derangement, and presence of other injuries (head or trunk) were associated with reduced survival rates. When the expertise to deal with such a group of patients is not available, early transfer under safe conditions should be considered to improve survival rates.

Prevalence of long-bone non-unions.

Despite the enormous progress made during recent decades in the treatment of long-bone fractures, fracture healing is still haunted by complications and above all non-unions. Non-unions represent a particular challenge, and the difficulties surrounding their management are frequently underestimated. Knowledge of the epidemiology of long-bone non-union can assist the treating surgeon in the application of the optimum fracture treatment.

Fracture healing in osteoporotic fractures: is it really different? A basic science perspective.

Osteoporosis is a major health problem characterized by compromised bone strength that predisposes patients to an increased risk of fracture. Osteoporotic patients differ from normal subjects in bone mineral composition, bone mineral content, and crystallinity. Poor bone quality in patients with osteoporosis presents the surgeon with difficult treatment decisions. Much effort has been expended on improving therapies that are expected to preserve bone mass and thus decrease fracture risk. Manipulation of both the local fracture environment in terms of application of growth factors, scaffolds and mesenchymal cells, and systemic administration of agents promoting bone formation and bone strength has been considered as a treatment option from which promising results have recently been reported. Surprisingly, less importance has been given to investigating fracture healing in osteoporosis. Fracture healing is a complex process of bone regeneration, involving a well-orchestrated series of biological events that follow a definable temporal and spatial sequence that may be affected by both biological factors, such as age and osteoporosis, and mechanical factors such as stability of the osteosynthesis. Current studies mainly focus on preventing osteoporotic fractures. In recent years, the literature has provided evidence of altered fracture healing in osteoporotic bone, which may have important implications in evaluating the effects of new osteoporosis treatments on fracture healing. However, the mechanics of this influence of osteoporosis on fracture healing have not yet been clarified and clinical evidence is still lacking.

Enhancement of fracture healing with parathyroid hormone: preclinical studies and potential clinical applications.

Parathyroid hormone (PTH) has become the most widely studied hormone with regard to its administration to various species and their respective skeletal responses. Beyond its affirmative effect in osteoporosis treatment, systemic PTH administration seems to stimulate bone formation in the fracture healing process. According to preclinical experimental studies, once-daily administration of PTH enhances the morphometric and mechanical properties of fracture calluses and accelerates the normal fracture healing. Its anabolic effect is obvious even in low doses, as well as in cases of implant fixation and distraction osteogenesis. There is little evidence of toxic effects and there are only a few reports of adverse events related to its use. The incidence of bone neoplasms in animal studies depends on the dose and duration of treatment. However, it is not prognostic of an equivalent risk potential of carcinogenesis in humans. In summary, the clinical promise of parathyroid hormone is very high and a positive effect in fracture healing should be anticipated.

Fat embolism: the reaming controversy.

Intramedullary nailing is the preferred treatment method for stabilizing femoral diaphyseal fractures. Despite its superior biomechanical advantages over other implants, its use, particularly in selected groups of patients, has been questioned because of the possible harmful systemic effects of intramedullary reaming. The increase in intramedullary canal pressure during intramedullary nailing can result in intravasation of bone marrow and fat into the venous blood system. The subsequent consequences can be fat embolism syndrome (FES), adult respiratory distress syndrome (ARDS), and multiple organ failure. The lung seems to be the primary target for fat embolization and for the mediated effects primed by inflammatory reactions. In laboratory studies, both reamed and unreamed intramedullary nailing has been shown to alter selected pulmonary variables. Although transient, this effect appears to be more prominent with reamed than unreamed techniques. Additional studies are required to determine whether a subgroup of trauma patients is adversely affected by intramedullary reaming, thus necessitating other fixation techniques.

Gene therapy in orthopaedics.

Impressive advances in our knowledge of the molecular genetic basis of skeletal disorders and fracture healing have led to the development of novel therapeutics based on ectopic expression of one or more genes in patient cells that can influence repair or regenerative processes in bone. Gene therapy is an attractive new approach to the treatment of bone disorders. Orthopaedics has become one of the most promising areas of research into gene therapy. This is because many potential orthopaedic targets for gene therapy, unlike traditional targets such as cancer and severe genetic disorders, neither present difficult delivery problems nor require prolonged periods of gene expression. Gene therapy offers new possibilities for the clinical management of orthopaedic conditions that are difficult to treat by traditional surgical or medical means. Impaired bone healing, need for extensive bone formation, cartilage repair and metabolic bone diseases are all conditions where alterations of the signalling peptides involved may provide cure or improvement. In orthopaedic oncology, gene therapy may achieve induction of tumour necrosis and increased tumour sensitivity to chemotherapy. An increasing amount of evidence indicates that gene transfer can aid the repair of articular cartilage, menisci, intervertebral disks, ligaments and tendons. These developments have the potential to transform many areas of musculoskeletal care, leading to treatments that are less invasive, more effective and less expensive than existing modalities.

Staged management and outcome of combined pelvic and liver trauma. An international experience of the deadly duo.

Pelvic fracture associated with liver trauma is not an uncommon injury combination in multiple trauma and is associated with high morbidity and mortality. The aim of this study was to examine the characteristics of this specific patient group, to describe the diagnostic and treatment protocols and finally to analyse risk factors associated with mortality. Data were collected over a 6-year period, ending in 2001. The pelvic injury was graded according to the Tile classification system and the hepatic injury was scored using the organ injury scale (OIS). Treatment protocol, associated injuries, complications, length of ICU/Hospital stay and mortality were recorded and analysed. A total of 140 patients (40% female) with a mean age of 35.1+/-15.9 years and a median ISS of 41 were included in this study. The overall mortality rate was 40.7%. Binomial logistic regression analysis revealed age, initial blood pressure, transfusion requirement as well as the severity of head, chest, spleen and liver injury as independent parameters predicting reduced survival rates. This deadly duo of injuries presents a challenge to the trauma surgeon. Rapid assessment and treatment is required to prevent death by haemorrhage. The presence of concomitant injuries renders the patient very sensitive to ongoing or additional physiological disturbance. The principles of 'damage control surgery' must be applied to avoid complications such as acute respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS).

The Safety and Efficacy of Parathyroid Hormone (PTH) as a Biological Response Modifier for the Enhancement of Bone Regeneration.

Osteoporosis is characterized by low bone mineral density and deterioration in the microarchitecture of bone that increases its fracture vulnerability. The mainstay of therapy for osteoporosis is anti-resorptive in mechanism. Parathyroid hormone (PTH) is the most recently approved anabolic agent for osteoporosis. The mechanism of PTH's skeleton anabolic action is composite involving pathways linked to common signalling peptides that affect gene osteoblast transcription. A number of animal studies and clinical trials have demonstrated that intermittent PTH administration induces anabolic effects on both cancellous and cortical bone, enhances bone mass and increases mechanical bone strength, increasing spine and hip bone mineral density and reducing fragility fractures. Preclinical studies investigating the effect of PTH on fracture healing show an increase in bone density and strength indicating an enhancement of this biological cascade. Preclinical and clinical safety assessments have revealed little evidence of toxic effects and there have been few reports of adverse events related to their use. An increase in osteosarcoma in rats probably is not prognostic of an equivalent possibility in humans. In summary, parathyroid hormone is a major advance in the treatment of osteoporosis. Additional studies addressing long-term clinical safety are needed. However the current evidence is very promising.

Clinical applications of BMP-7: the UK perspective.

Treatment of fracture non-union is a challenging situation in skeletal surgery. Since the discovery of bone morphogenetic proteins (BMPs) by Urist preclinical research as well as clinical trials has shown the efficacy of these molecules in bone healing enhancement. Recombinant bone morphogenetic protein became available in UK during August 2001. We evaluated the type of indications and the efficacy of BMP-7 in a variety of clinical conditions including persistent fracture non-unions, augmentation of periprosthetic fracture treatment and osteotomies, enhancement of fracture healing following acetalular reconstruction, distraction osteogenesis, free fibular graft and arthrodesis of joints. Out of 653 cases, the overall success rate was 82% (535 cases). No local or systemic adverse effects were encountered. The role of BMP's as a bone stimulating agent is safe, well established and could be considered as a power adjunct in the surgeon's armamentarium for the treatment of these challenging clinical conditions.

Role of long stem revision knee prosthesis in periprosthetic and complex distal femoral fractures: a review of eight patients.

Eight patients, six with periprosthetic and two with complex distal femoral fractures (one pathological, and one with failed internal fixation) were treated with a cemented long stem revision arthroplasty prosthesis to address the issues of articular comminution, stability, alignment and early mobilisation. The average age of the patients was 78 years (range 39-81). There were no intra-operative complications. The mean hospital stay was 12 days (range 8-21). Post-operative complications included one case of posterior dislocation and one superficial infection. All patients had remarkable symptomatic relief at 3 months as indicated by the visual analogue scores. All periprosthetic fractures achieved bony union at a mean time of 3.8 months. The mean follow up was 24 months (range 14-42). The American Knee Society score revealed one 'excellent', five 'good', one 'satisfactory' and one 'poor' result. The mean loss of extension was 7.7 degrees (range 5 degrees -15 degrees ) and the mean flexion achieved was 66 degrees (range: 15 degrees to 85 degrees ). The mean alignment was 6 degrees (range 0 degrees -10 degrees ) valgus. This study highlights the role of long stem prosthesis in periprosthetic and some complex distal femoral fractures in offering stability and early mobilisation.