Biologic treatment of mild and moderate intervertebral disc degeneration.

Disc degeneration is the most common cause of back pain in adults and has enormous socioeconomic implications. Conservative management is ineffective in most cases, and results of surgical treatment have not yet reached desirable standards. Biologic treatment options are an alternative to the above conventional management and have become very attractive in recent years. The present review highlights the currently available biologic treatment options in mild and moderate disc degeneration, where a potential for regeneration still exists. Biologic treatment options include protein-based and cell-based therapies. Protein-based therapies involve administration of biologic factors into the intervertebral disc to enhance matrix synthesis, delay degeneration or impede inflammation. These factors can be delivered by an intradiscal injection, alone or in combination with cells or tissue scaffolds and by gene therapy. Cell-based therapies comprise treatment strategies that aim to either replace necrotic or apoptotic cells, or minimize cell death. Cell-based therapies are more appropriate in moderate stages of degenerated disc disease, when cell population is diminished; therefore, the effect of administration of growth factors would be insufficient. Although clinical application of biologic treatments is far from being an everyday practice, the existing studies demonstrate promising results that will allow the future design of more sophisticated methods of biologic intervention to treat intervertebral disc degeneration.

Thumb Distal Phalanx Giant Enchondroma. A Case Presentation and Literature Review.

Background: Enchordoma of the distal phalange of the thumb is extremely rare. Case presentation: We report a case of 31-year-old man who presented with a pathological fracture of the left thumb. Imaging evaluation revealed a lytic lesion and surgical curettage with bone graft was performed after fracture healing. Histological examination confirmed the diagnosis of enchordoma. The postoperative period was uncomplicated without signs of recurrence. Conclusion:Lytic lesions in the thumb are uncommon occurrences and necessitate a comprehensive examination to determine their potential causes. Given the significant functional role of the thumb compared to other fingers, it is crucial to undergo radiological assessment and further investigation of these lytic lesions.

Sagittal Balance Parameters and Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis.

Background: To review and evaluate multiple preoperative and postoperative sagittal parameters and their association with the risk of developing proximal junctional kyphosis (PJK) in patients with adolescent idiopathic scoliosis (AIS) who undergo correction surgery. Methods: A systematic search was performed in December 2022 in PubMed, Embase and the Cochrane Library to retrieve all the studies relevant to our research. After the study selection and data extraction following PRISMA guidelines, RevMan 5.3 was used for statistical analysis. All the analyzed factors were evaluated by using odds ratios and weighted mean differences with 95% confidence intervals. Moreover, the meta-analysis of proportions via MedCalc was used for analyzing quantitative data from the studies. Results: A total of 22 studies were included in our meta-analysis. All the available values of sagittal parameters were evaluated. Among all the potential risk factors, higher preoperative thoracic kyphosis (Test for overall effect Z = 11.79, p < 0.00001), higher preoperative sagittal vertical axis (SVA) (test for overall effect Z = 11.19, p < 0.00001), greater thoracic kyphosis change post-op. compared to pre-op. (test for overall effect Z = 6.02, p < 0.00001), increased postoperative lumbar lordosis (test for overall effect Z = 3.65, p = 0.0003), higher post-op. SVA (test for overall effect Z = 24.93, p < 0.00001) and a larger pelvic incidence/lumbar lordosis (PI/LL) mismatch (test for overall effect Z = 20.50, p < 0.00001) were found to be the risk factors for PJK after AIS surgery. Moreover, a decreased rod contour angle (RCA) (test for overall effect Z = 3.79, p < 0.0002) and higher proximal junctional angle-rod contour angle (PJA-RCA) (test for overall effect Z = 39.18, p < 0.00001) play a significant role in the risk of developing PJK after AIS correction. Conclusions: Sagittal balance is of great importance when considering the surgical correction of AIS. Many factors in our meta-analysis were found to increase the incidence for PJK such as higher preoperative thoracic kyphosis and pre-op. SVA. Furthermore, increased thoracic kyphosis change, increased post-operative lumbar lordosis, SVA and PI/LL mismatch are also factors that influence the possibility of post-op. PJK. Lastly, RCA and PJA-RCA are two important factors that need attention during AIS, as over-contouring of the rod could lead to PJK in AIS patients.

Multiplex cytokine analysis for the identification of novel potential synovial fluid biomarkers for periprosthetic joint infections.

INTRODUCTION: Periprosthetic joint infections (PJIs) are a devastating complication of total hip (THA) and knee (TKA) arthroplasty. The use of novel techniques like multiplex cytokine analysis could contribute immensely to the identification of potential novel biomarkers. PATIENTS AND METHODS: This is a single-centre study of patients that were treated with revision TKA, THA or hemiarthroplasty. Serum's white blood cells (WBCs), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) and synovial fluid's WBCs, percentage of polymorphonuclear neutrophils (%PMNs) and CRP were measured. Proteomic analysis targeting the secreted cytokines in synovial fluid was conducted using a 73-plex assay panel. The results were statistically compared between the septic and aseptic cases and ROC analysis to establish the area under the curve (AUC), sensitivity and specificity of each biomarker. RESULTS: The study included 30 patients (18 revision THA cases; 3 conversion of hemiarthroplasty to THA and 9 revision TKA cases); 14 cases were considered infected, 1 likely infected and 15 not infected. The results showed statistically significant differences (p < 0.05) between infected and not infected cases in serum's ESR, CRP and synovial fluid's%PMNs, growth-regulated oncogene alpha (GROA), interleukin-8, interleukin-5, S100-A8/calprotectin and resistin (RETN) with AUCs of 0.75, 0.72, 0.95, 0.75, 0.72, 0.95, 0.83, 0.73, 0.75, 0.81 and 0.76 respectively. CONCLUSIONS: In the present study, serum ESR and CRP as well as synovial %PMNs, GROA, IL-8, IL-5, calprotectin and RETN protein levels were identified as potential biomarkers. Further studies are needed to further investigate their diagnostic utility and optimal cut-off values.

Electrical Stimulation and Motor Function Rehabilitation in Spinal Cord Injury: A Systematic Review.

Spinal cord injury (SCI) often leads to devastating motor impairments, significantly affecting the quality of life of affected individuals. Over the last decades, spinal cord electrical stimulation seems to have encouraging effects on the motor recovery of impacted patients. This review aimed to identify clinical trials focused on motor function recovery through the application of epidural electrical stimulation, transcutaneous electrical stimulation, and functional electrical stimulation. Several clinical trials met these criteria, focusing on the impact of the aforementioned interventions on walking, standing, swimming, trunk stability, and upper extremity functionality, particularly grasp. After a thorough PubMed online database research, 37 clinical trials were included in this review, with a total of 192 patients. Many of them appeared to have an improvement in function, either clinically assessed or recorded through electromyography. This review outlines the various ways electrical stimulation techniques can aid in the motor recovery of SCI patients. It stresses the ongoing need for medical research to refine these techniques and ultimately enhance rehabilitation results in clinical settings.

Unraveling the Link of Altered TGFß Signaling with Scoliotic Vertebral Malformations in Osteogenesis Imperfecta: A Comprehensive Review.

Osteogenesis Imperfecta (OI) is a genetic disorder caused by mutations in genes responsible for collagen synthesis or polypeptides involved in the formation of collagen fibers. Its predominant skeletal complication is scoliosis, impacting 25 to 80% of OI patients. Vertebral deformities of the scoliotic curves in OI include a variety of malformations such as codfish, wedged-shaped vertebrae or platyspondyly, craniocervical junction abnormalities, and lumbosacral spondylolysis and spondylolisthesis. Although the precise pathophysiology of these spinal deformities remains unclear, anomalies in bone metabolism have been implicated in the progression of scoliotic curves. Bone Mineral Density (BMD) measurements have demonstrated a significant reduction in the Z-score, indicating osteoporosis and a correlation with the advancement of scoliosis. Factors such as increased mechanical strains, joint hypermobility, lower leg length discrepancy, pelvic obliquity, spinal ligament hypermobility, or vertebrae microfractures may also contribute to the severity of scoliosis. Histological vertebral analysis has confirmed that changes in trabecular microarchitecture, associated with inadequate bone turnover, indicate generalized bone metabolic defects in OI. At the molecular level, the upregulation of Transforming Growth factor-ß (TGFß) signaling in OI can lead to disturbed bone turnover and changes in muscle mass and strength. Understanding the relationship between spinal clinical features and molecular pathways could unveil TGFß -related molecular targets, paving the way for novel therapeutic approaches in OI.

The Effect of PRP Augmentation of Arthroscopic Repairs of Shoulder Rotator Cuff Tears on Postoperative Clinical Scores and Retear Rates: A Systematic Review and Meta-Analysis.

The aim of this review and meta-analysis is to assess recent clinical trials concerning the combination of operative treatment of rotator cuff tears and the administration of PRP and its effect on clinical scores and postoperative retear rates. The trials were used to compare the combination of PRP treatment and arthroscopic rotator cuff repair to arthroscopy alone. Twenty-five clinical trials were reviewed. A risk-of-bias assessment was made for all randomized clinical trials included, using the Cochrane collaboration's tool as well as a quality assessment for all non-randomized studies utilizing the Newcastle−Ottawa scale. The PRP-treated patients showed statistically significant improvement postoperatively compared to control groups concerning the Constant−Murley (mean difference 2.46, 95% CI 1.4−3.52, p < 0.00001), SST (mean difference 0.32, 95% CI 0.02−0.63, p = 0.04), and UCLA (mean difference 0.82, 95% CI 0.23−1.43, p = 0.07) scores. A statistically significant decrease of retear rates in the PRP-treated patients, with a risk ratio of 0.78 (95% CI 0.65−0.94, p = 0.01), was found. We believe that the results presented have positive aspects, especially concerning the retear risk, but are yet inconclusive concerning clinical results such as shoulder pain and function.

The Role of Sclerostin in Bone Diseases.

Sclerostin has been identified as an important regulator of bone homeostasis through inhibition of the canonical Wnt-signaling pathway, and it is involved in the pathogenesis of many different skeletal diseases. Many studies have been published in the last few years regarding sclerostin's origin, regulation, and mechanism of action. The ongoing research emphasizes the potential therapeutic implications of sclerostin in many pathological conditions with or without skeletal involvement. Antisclerostin antibodies have recently been approved for the treatment of osteoporosis, and several animal studies and clinical trials are currently under way to evaluate the effectiveness of antisclerostin antibodies in the treatment of other than osteoporosis skeletal disorders and cancer with promising results. Understanding the exact role of sclerostin may lead to new therapeutic approaches for the treatment of skeletal disorders.

A Systematic Review of the Diagnosis and Treatment of Non-Typhoid Salmonella Spondylodiscitis in Immunocompetent Children.

The aim of this systematic review is to distinguish the clinical features of immunocompetent children with non-typhoid Salmonella spondylodiscitis and summarize the diagnosis, diagnostic tools, and treatment methods to guide clinicians. The review was conducted according to the preferred PRISMA guidelines. We conducted a literature search in the PubMed, Embase, and Cochrane Library databases. Article screening, data extraction, and study evaluation were performed by two independent reviewers. A total of 20 articles, published between 1977 and 2020, were selected, which included 21 patients with average age of 12.76 years (range, 2-18) without comorbidities; in total, 19% of the patients had positive blood cultures for non-typhoid Salmonella, and 80.9% underwent either CT-guided or open biopsy, which were positive for NTS. All infections were monomicrobial, and 11 different serotypes of non-typhoid Salmonella were identified. Analyzing the reviewed cases, 52.4% of the patients presented with fever, 90.5% had localized pain, and only 19% had gastroenteritis. The most common level of discitis was the lumbar region, especially the L4/L5 level. Primarily, third-generation cephalosporin was administered, and antibiotic treatment was given for an average of 9.6 weeks. Non-typhoid Salmonella spondylodiscitis is a rare clinical entity in healthy and immunocompetent children. The identification of the responsible organism is essential to guide antibiotic therapy and define the treatment duration. A significant limiting factor in this systematic review was the lack of published research articles and case series due to the rarity of the disease.

Therapeutic Efficacy and Safety of Osteoinductive Factors and Cellular Therapies for Long Bone Fractures and Non-Unions: A Meta-Analysis and Systematic Review.

BACKGROUND: Long bone fractures display significant non-union rates, but the exact biological mechanisms implicated in this devastating complication remain unclear. The combination of osteogenetic and angiogenetic factors at the fracture site is an essential prerequisite for successful bone regeneration. The aim of this study is to investigate the results of the clinical implantation of growth factors for intraoperative enhancement of osteogenesis for the treatment of long bone fractures and non-unions. METHODS: A systematic literature review search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in the PubMed and Web of Science databases from the date of inception of each database through to 10 January 2022. Specific inclusion and exclusion criteria were applied in order to identify relevant studies reporting on the treatment of upper and lower limb long bone non-unions treated with osteoinductive or cellular factors. RESULTS: Overall, 18 studies met the inclusion criteria and examined the effectiveness of the application of Bone Morphogenetic Proteins-2 and -7 (BMPs), platelet rich plasma (PRP) and mesenchymal stem cells (MSCs). Despite the existence of limitations in the studies analysed (containing mixed groups of open and close fractures, different types of fractures, variability of treatment protocols, different selection criteria and follow-up periods amongst others), their overall effectiveness was found significantly increased in patients who received them compared with the controls (I2 = 60%, 95% CI = 1.59 [0.99-2.54], Z =1.93, p = 0.05). CONCLUSION: Administration of BMP-2 and -7, PRP and MSCs were considered effective and safe methods in fracture treatment, increasing bone consolidation, reducing time to repair and being linked to satisfactory postoperative functional scores.

Current Aspects on the Pathophysiology of Bone Metabolic Defects during Progression of Scoliosis in Neurofibromatosis Type 1.

Neurofibromatosis type 1 (NF1), which is the most common phacomatoses, is an autosomal dominant disorder characterized by clinical presentations in various tissues and organs, such as the skin, eyes and nervous and skeletal systems. The musculoskeletal implications of NF1 include a variety of deformities, including scoliosis, kyphoscoliosis, spondylolistheses, congenital bony bowing, pseudarthrosis and bone dysplasia. Scoliosis is the most common skeletal problem, affecting 10-30% of NF1 patients. Although the pathophysiology of spinal deformities has not been elucidated yet, defects in bone metabolism have been implicated in the progression of scoliotic curves. Measurements of Bone Mineral Density (BMD) in the lumbar spine by using dual energy absorptiometry (DXA) and quantitative computer tomography (QCT) have demonstrated a marked reduction in Z-score and osteoporosis. Additionally, serum bone metabolic markers, such as vitamin D, calcium, phosphorus, osteocalcin and alkaline phosphatase, have been found to be abnormal. Intraoperative and histological vertebral analysis confirmed that alterations of the trabecular microarchitecture are associated with inadequate bone turnover, indicating generalized bone metabolic defects. At the molecular level, loss of function of neurofibromin dysregulates Ras and Transforming Growth factor-ß1 (TGF-ß1) signaling and leads to altered osteoclastic proliferation, osteoblastic activity and collagen production. Correlation between clinical characteristics and molecular pathways may provide targets for novel therapeutic approaches in NF1.

Sonication of revised hip and knee prostheses detects occult infections, improves clinical outcomes and prevents re - revisions. A case series study.

Introduction: Periprosthetic joint infection (PJI) is a devastating complication occurring in 1-2% of primary and up to 10% of revised total hip and knee arthroplasties (THA and TKA) impairing patient's quality of life. Occult infections are underdiagnosed, sub-treated and sub-clinically experienced by patients. This study aimed to correlate patients' clinical outcomes with early antibiotic treatment based on use or non-use of a sonication technique on explanted prostheses. Methods: 33 patients with revised THA or TKA were retrospectively evaluated. Clinical outcomes were assessed via Oxford hip or knee scores, and correlated with administration or not of antibiotic treatment based on sonication results. Results: According to laboratory findings the patients were divided in the following three groups: 1. Septic loosening (conventional cultures and/or sonication positive), 2. Aseptic loosening (conventional cultures and sonication negative) and 3. Occult loosening (conventional cultures negative, sonication not performed). The average Oxford score was poor (27.9/60) for the septic, excellent (43.8/60) for the aseptic and intermediate (37.7/60) for the occult group. Additionally, conventional cultures were negative, but sonication-positive, in 6 individuals with patient-related risk factors (male gender, BMI > 30 kg/m2, diabetes, hypertension, steroids and rheumatoid arthritis). Conclusions: Sonication represents a valuable diagnostic technique to guide administration of effective antibiotic treatment for patients, especially for detection of persistent post-revision occult infections. We recommend the systematic investigation of revised prostheses with a sonication technique, but especially in cases with risk factors for infection who it is suspected may have occult loosening.

Sclerostin and Its Involvement in the Pathogenesis of Idiopathic Scoliosis.

Idiopathic scoliosis is a disorder of unknown etiology. Bone biopsies from idiopathic scoliosis patients revealed changes at cellular and molecular level. Osteocytic sclerostin is downregulated, and serum level of sclerostin is decreased. Osteocytes in idiopathic scoliosis appear to be less active with abnormal canaliculi network. Differentiation of osteoblasts to osteocytes is decelerated, while Wnt/ß-catenin signaling pathway is overactivated and affects normal bone mineralization that leads to inferior mechanical properties of the bone, which becomes susceptible to asymmetrical forces and causes deformity of the spinal column. Targeting bone metabolism during growth by stimulating sclerostin secretion from osteocytes and restoring normal function of Wnt/ß-catenin signaling pathway could, in theory, increase bone strength and prevent deterioration of the scoliotic deformity.

Two stage surgical treatment of cuboid osteomyelitis. A case report and review of the literature.

Isolated osteomyelitis of the cuboid bone is an extremely rare condition. A 32 year old man was evaluated for a painful and swollen right foot after a penetrating trauma and the presence of a sinus in the lateral aspect the midfoot. MRI findings were consistent with the presence of cuboid osteomyelitis. The patient underwent a two stage procedure which included partial excision of the cuboid bone, the use of a cemented spacer for lateral column length preservation, followed by arthrodesis of the calcaneocuboid joint with a tricortical autologous bone graft harvested from the ilium and preservation of the cuboid-metatarsal joints. At 4 years follow up, the patient is asymptomatic. Diagnosis of isolated cuboid osteomyelitis requires high clinical suspicion and a two stage procedure is an effective approach for symptomatic patients who do not respond to conservative treatment. LEVEL OF CLINICAL EVIDENCE: IV.

Braces for idiopathic scoliosis in adolescents.

BACKGROUND: Adolescent Idiopathic Scoliosis (AIS) is a three-dimensional deformity of the spine. While AIS can progress during growth and cause a surface deformity, it is usually not symptomatic. However, in adulthood, if the final spinal curvature surpasses a certain critical threshold, the risk of health problems and curve progression is increased. Braces are traditionally recommended to stop curvature progression in some countries and criticized in others. They generally need to be worn full time, with treatment extending over years. OBJECTIVES: To evaluate the efficacy of bracing in adolescent patients with AIS. SEARCH STRATEGY: The following databases (up to July 2008) were searched with no language limitations: the Cochrane Central Register of Controlled Trials, MEDLINE (from January 1966), EMBASE (from January 1980), CINHAL (from January 1982) and reference lists of articles. An extensive handsearch of the grey literature was also conducted. SELECTION CRITERIA: Randomised controlled trials and prospective cohort studies comparing braces with no treatment, other treatment, surgery, and different types of braces. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trial quality and extracted data. MAIN RESULTS: We included two studies. There was very low quality evidence from one prospective cohort study with 286 girls that a brace curbed curve progression at the end of growth (success rate 74% (95% CI: 52% to 84%)), better than observation (success rate 34% (95% CI:16% to 49%)) and electrical stimulation (success rate 33% (95% CI:12% to 60%)). There is low quality evidence from one RCT with 43 girls that a rigid brace is more successful than an elastic one (SpineCor) at curbing curve progression when measured in Cobb degrees, but there were no significant differences between the two groups in the subjective perception of daily difficulties associated with wearing the brace. AUTHORS' CONCLUSIONS: There is very low quality evidence in favour of using braces, making generalization very difficult. Further research could change the actual results and our confidence in them; in the meantime, patients' choices should be informed by multidisciplinary discussion. Future research should focus on short and long-term patient-centred outcomes, in addition to measures such as Cobb angles. RCTs and prospective cohort studies should follow both the Scoliosis Resarch Society (SRS) and Society on Scoliosis Orthopaedic and Rehabilitation Treatment (SOSORT) criteria for bracing studies.

Cosmetic outcome after conservative treatment of idiopathic scoliosis with a dynamic derotation brace.

Improved cosmesis is a major concern for the adolescents with Idiopathic Scoliosis (IS). We hypothesized that if we correct the rotation simultaneously to the lateral curvature of the spine with a dynamic brace we may decrease the asymmetry of the back and ultimately improve the cosmetic appearance of the scoliotic child. Thirty six scoliotic children (32 girls and 4 boys) with a mean age of 13.9 (range 12-17) years, a mean Cobb angle of 28.2 degrees (range 19-38 degrees ) and a mean ATI 7.8 degrees (range 4 degrees -17 degrees ) were studied. The examined children were divided in 3 subgroups according to the curve type. All children wore the Dynamic Derotation Brace (DDB), which is a modified Boston brace with antirotatory blades, for 23 hours per day, for a minimum duration of 2 years. The ATI was assessed using the Pruijs scoliometer at baseline and at the end of treatment. ATI was improved statistically significant in the thoracolumbar (p < 0.01) and lumbar region (p < 0.013) of double curves and in the thoracolumbar (p < 0.018) and lumbar region (p < 0.027) of thoracolumbar curves. ATI improvement in the thoracic region was not statistically significant either in double curves (p < 0.088) or in thoracolumbar curves (p < 0.248). For right thoracic curves, ATI improvement was not statistically significant for all the examined regions. The above findings indicate that in double and thoracolumbar curves, a deforming torsional force is present, blocked by the antirotatory action of the blades of the DDB, and seems to be more active in the "lower" spine. In conclusion, DDB improves the cosmetic appearance of the back of IS children with all but right thoracic curves.

School screening as a research tool in epidemiology, natural history and aetiology of idiopathic scoliosis.

The aim of school screening is to identify most or all the individuals with unrecognized idiopathic scoliosis (IS) at an early stage when a less invasive treatment is more effective. However like other medical screening programs it has not escaped controversy about its value. The present study summarises the contribution of school screening in research of IS epidemiology, natural history and aetiology. Such contribution is beyond the original aim of school screening but is very important to expand our knowledge and adequately understand the pathogenesis of IS. The role of biological factors such as the menarche, the lateralization of the brain, the handedness, the thoracic cage, the intervertebral disc, the melatonin secretion, as well as the role of environmental factors such as the light and the impact of the geographical latitude in IS prevalence were studied in children referred from school screening. The present study provides evidence to support that school screening programs should be continued not only for early detection of IS but also as a basis for epidemiological surveys until we learn much more about the aetiology of IS.

How to improve the effectiveness of school screening for idiopathic scoliosis.

The value of school screening for idiopathic scoliosis (IS) has been questioned recently, because of its high false positive referrals and its excessive cost, although in areas where screening programs exist, fewer patients ultimately require surgery for IS. In a typical school screening setting there are numerous factors which can determine the effectiveness. The present study identifies some of these factors and provides evidence based recommendations for the improvement of school screening effectiveness. After reviewing all the research papers which originated from the Thriasio school screening program and published in peer-review journals, specific suggestions for the organization, the optimal age of screening according to the geographical latitude, the best examined position, the standardization of referrals, the follow up of younger referrals with trunk asymmetry and the reduction of the financial cost are made. We strongly suggest the introduction of these recommendations to all the existing school screening programs in order to improve their effectiveness and to reduce the negative impact they may have on families and on the health system.

Strategies for managing bone defects of the lower extremity.

Management of posttraumatic segmental bone loss as a result of severe open injuries of the lower extremity, high-energy closed injuries, and following failed initial treatment of complex fractures that develop pseudarthrosis continues to challenge reconstructive surgeons. There are numerous strategies for dealing with such injuries but the outcome is unpredictable. The procedure is rarely only one stage and complications frequently arise. In most cases the reconstruction process is long and difficult and amputation must be part of the decision-making process. All traditional treatment strategies have advantages and major drawbacks. To overcome some limitations, biologic treatments have been developed based on specific pathways of bone physiology and healing.

Expression of matrix metalloproteinase-1 (MMP-1) in Wistar rat's intervertebral disc after experimentally induced scoliotic deformity.

INTRODUCTION: A scoliotic deformity on intervertebral discs may accelerate degeneration at a molecular level with the production of metalloproteinases (MMPs). In the present experimental study we evaluated the presence of MMP-1 immunohistochemically after application of asymmetric forces in a rat intervertebral disc and the impact of the degree of the deformity on MMP-1 expression. MATERIAL-METHOD: Thirty female Wistar rats (aged 2 months old, weighted 200 ± 10 grams) were used. All animals were age, weight and height matched. A mini Ilizarov external fixator was applied at the base of a rat tail under anaesthesia in order to create a scoliotic deformity of the intervertebral disc between the 9th and 10th vertebrae. Rats were divided into three groups according to the degree of the deformity. In group I, the deformity was 10°, in group II 30° and in group III 50°. The rats were killed 35 days after surgery. The discs were removed along with the neighbouring vertebral bodies, prepared histologically and stained immunohistochemically. Immunopositivity of disc's cells for MMP-1 was determined using a semi-quantitative scored system. RESULTS: MMP-1 immunopositivity was detected in disc cells of annulus fibrosus of all intervertebral disc specimens examined. The percentage of MMP-1 positive disc cells in annulus fibrosus in group I, II and III were 20%, 43% and 75%, respectively. MMP-1 positivity was significantly correlated with the degree of the deformity (p < 0,001). An increase of chondrocyte-like disc cells was observed in the outer annulus fibrosus and at the margin of the intervertebral disc adjacent to the vertebral end plates. The difference in the proportion of MMP-1 positive disc cells between the convex and the concave side was statistically not significant in group I (p = 0,6), in group II this difference was statistically significant (p < 0,01). In group III the concave side showed a remarkable reduction in the number of disc's cells and a severe degeneration of matrix microstructure. CONCLUSION: The present study showed that an experimentally induced scoliotic deformity on a rat tail intervertebral disc results in over-expression of MMP-1, which is dependent on the degree of the deformity and follows a dissimilar distribution between the convex and the concave side.