Improvement of Orthopedic Residency Programs and Diversity: Dilemmas and Challenges, an International Perspective.

BACKGROUND: To date, little has been published comparing the structure and requirements of orthopedic training programs across multiple countries. The goal of this study was to summarize and compare the characteristics of orthopedic training programs in the U.S.A., U.K., Canada, Australia, Germany, India, China, Saudi Arabia, Russia and Iran. METHODS: We communicated with responders using a predetermined questionnaire regarding the national orthopedic training program requirements in each respondent's home country. Specific items of interest included the following: the structure of the residency program, the time required to become an orthopedic surgeon, whether there is a log book, whether there is a final examination prior to becoming an orthopedic surgeon, the type and extent of faculty supervision, and the nature of national in-training written exams and assessment methods. Questionnaire data were augmented by reviewing each country's publicly accessible residency training documents that are available on the web and visiting the official website of the main orthopedic association of each country. RESULTS: The syllabi consist of three elements: clinical knowledge, clinical skills, and professional skills. The skill of today's trainees predicts the quality of future orthopedic surgeons. The European Board of Orthopedics and Traumatology (EBOT) exam throughout the European Union countries should function as the European board examination in orthopedics. We must standardize many educational procedures worldwide in the same way we standardized patient safety. CONCLUSION: Considering the world's cultural and political diversity, the world is nearly unified in regards to orthopedics. The procedures (structure of the residency programs, duration of the residency programs, selection procedures, using a log book, continuous assessment and final examination) must be standardized worldwide, as implemented for patient safety. To achieve this goal, we must access and evaluate more information on the residency programs in different countries and their needs by questioning them regarding what they need and what we can do for them to make a difference.

Extra- vs. intramedullary treatment of pertrochanteric fractures: a biomechanical in vitro study comparing dynamic hip screw and intramedullary nail.

INTRODUCTION: Due to the demographic trend, pertrochanteric fractures of the femur will gain increasing importance in the future. Both extra- and intramedullary implants are used with good results in the treatment of these fractures. New, angular stable extramedullary implants promise increased postoperative stability even with unstable fractures. Additional trochanteric plates are intended to prevent secondary impaction, varisation and shortening of the fracture, as well as medialisation of the femoral shaft. The aim of this study was to perform a biomechanical comparison of both procedures regarding their postoperative stability and failure mechanisms. MATERIALS AND METHODS: Twelve fresh-frozen human femurs were randomized into two groups based on the volumetric bone mineral density (vBMD). Standardized pertrochanteric fractures (AO31-A2.3) were generated and treated either with an angular stable dynamic hip screw (DHS) or an intramedullary nail (nail). Correct implant position and the tip-apex distance (TAD) were controlled postoperatively using X-ray. Specimens were mounted in a servohydraulic testing machine and an axial loading was applied according to a single-leg stance model. Both groups were biomechanically compared with regard to native and postoperative stiffness, survival during cyclic testing, load to failure, and failure mechanisms. RESULTS: TAD, vBMD, and native stiffness were similar for both groups. The stiffness decreased significantly from native to postoperative state in all specimens (p < 0.001). The postoperative stiffness of both groups varied non-significantly (p = 0.275). The failure loads for specimens treated with the nail were significantly higher than for those treated with the DHS (8480.8 ± 1238.9 N vs. 2778.2 ± 196.8 N; p = 0.008). CONCLUSIONS: Extra- and intramedullary osteosynthesis showed comparable results as regards postoperative stiffness and survival during cyclic testing. Since the failure load of the nail was significantly higher in the tested AO31-A2.3 fracture model, we conclude that intramedullary implants should be preferred in these, unstable, fractures.

Treatment of osteochondral fractures of the knee: a meta-analysis of available scientific evidence.

PURPOSE: Although traumatic osteochondral fractures of the knee represent a common pathology of the knee joint, there is no general agreement concerning specific treatment of this entity. This meta-analysis was initiated in order to evaluate scientific evidence on different treatment options for acute osteochondral fractures of the knee. METHODS: For this purpose an OVID-based systematic literature search was performed including the following databases: MEDLINE, MEDLINE preprints, Embase, CINAHL, Life Science Citations, British National Library of Health and Cochrane Central Register of Controlled Trials. The literature search period was from 1946 to January 2012, which led to the identification of 1,226 articles. After applying study-specific inclusion criteria a total of 19 studies with clinical follow-up of 638 patients were included. The methodology of these studies was systematically analysed by means of the Coleman Methodology Score. Outcome and success rates were evaluated depending on treatment applied. RESULTS: All studies (n = 19) identified represent case series (evidence-based medicine level IV) and included a total of 638 patients. The average post-operative follow-up was 46 ± 27 months (range 3.75-108). The mean number of study subjects per study was 33 ± 44 patients (range 4-169). The average Coleman Methodology Score was 29 ± 17 points (range 5-72). Six different scoring systems were used for clinical assessment. The overall clinical success rate was 83% and varied between 45 and 100%. CONCLUSIONS: This meta-analysis reveals a significant lack of scientific evidence for treatment of osteochondral fractures of the knee. No valid conclusion can be drawn from this study concerning the recommendation of a specific treatment algorithm. Nevertheless, the overall failure rate of 17% underlines that an acute osteochondral fracture of the knee represents an important pathology which is not a self-limiting injury and needs further investigation.

CaReS (MACT) versus microfracture in treating symptomatic patellofemoral cartilage defects: a retrospective matched-pair analysis.

BACKGROUND: Treating patellofemoral articular cartilage lesions remains a challenging task in orthopedic surgery. Whereas microfracture and autologous chondrocyte implantation yield good results on femoral condyles, the therapeutic state of the art for treating patellofemoral lesions is yet to be determined. In this study, we compared the CaReS technique, which is a matrix-associated autologous chondrocyte implantation technique, to microfracture for treating patellofemoral articular cartilage lesions. METHODS: Between May 2003 and December 2005, 17 patients with an isolated patellofemoral cartilage defect (International Cartilage Repair Society III/IV) were treated with the CaReS technique at our department. After adjusting for inclusion and exclusion criteria, ten of these patients could be included in this study; ten patients treated with microfracture were chosen as a matched-pair group. Clinical outcome was evaluated 3 years after surgery by the 36-item Short Form Health Survey Questionnaire (SF-36), International Knee Documentation Committee (IKDC) subjective evaluation of the knee, Lysholm Score, and Cincinnati Modified Rating Scale scores. RESULTS: Patients treated with CaReS had statistically significantly improved IKDC, Lysholm, and Cincinnati scores 36 months after surgery compared with preoperatively. When comparing outcome between groups 36 months after surgery, there was no statistically difference in IKDC, Lysholm, and Cincinnati scores. CONCLUSIONS: This is the first trial comparing the CaReS technique and microfracture for treating patellofemoral articular cartilage lesions, and results show that CaReS(®) yields comparable results to microfracture. The small number of patients is a limiting factor of the study, leading to results without statistical significance. A multicentric prospective randomized study comparing the two procedures is desirable.

Bone marrow stromal cells in a liquid fibrin matrix improve the healing process of patellar tendon window defects.

Following injury, ligaments and tendons do not regain their normal biological and biomechanical status. This study analyzed whether an injection of human bone marrow stromal cells (BMSC) or human fibroblast in a liquid fibrin matrix influences the histological results, ultrastructural morphology, mRNA expression of essential extracellular matrix proteins, and material properties of the healing tissue. Standardized full-thickness, full-length defects of the central portion of patellar tendons were created in 96 immunodeficient rats, and filled with human BMSC in a fibrin matrix (BMSC group), human fibroblasts in a fibrin matrix (fibroblast group), or fibrin matrix only (matrix group), or left untreated (defect group). Histological sections revealed more mature tissue formation with more regular patterns of cell distribution in the BMSC group, without signs of ectopic tissue formation into bone or cartilage. Mean collagen fibril diameter and relative area covered by collagen fibrils were significantly higher at 10 and 20 days postoperatively in the BMSC group compared to the defect and matrix groups, and comparable to normal tendon tissue. Further, collagen I mRNA expression, collagen I/collagen III mRNA ratio, and Young's modulus were significantly increased at 20 days postoperatively in comparison to the defect and matrix groups. In the fibroblast group, only mean collagen fibril diameter was significantly higher compared to the defect group, whereas the other biological and biomechanical parameters were not significantly improved. This study reveals that an injection of BMSC in a liquid fibrin matrix stimulates histological, ultrastructural, molecular biologic, and biomechanical parameters of patellar tendon healing, whereas injection of fibroblasts in fibrin matrix had only minor effects on the stimulation of tendon healing.

Influence of fibrin glue on proliferation and differentiation of human bone marrow stromal cells seeded on a biologic 3-dimensional matrix.

For tissue engineering of bone, a carrier matrix and efficient cell seeding are desirable. This study analysed the effect of fibrin glue on bone marrow stromal cells (BMSC) adhesion, proliferation (MTS-Test), differentiation (alkaline phosphatase (AP), osteocalcin (OC), ELISA) and compared the results with cells seeded within culture media on a decellularized, xenogenic bone matrix. There was no significant difference regarding cell adhesion. Proliferation after one week was significantly increased without fibrin glue. AP was increased in both groups when compared with porous scaffolds without cells. OC secretion was increased under both seeding conditions. Microscopic investigation of the cells with fibrin-glue showed less cell-cell contacts. This study reveals that cell seeding with medium demonstrates similar adherence rates compared with fibrin glue. Fibrin glue significantly decreases cell proliferation. Cell differentiation with respect to ALP and OC is not affected. Further studies are required to assess the long term and in vivo effects of both methods with respect to BMSC viability and differentiation. Fibrin sealants seem not necessary to achieve cell adherence when using a porous bone matrix.

A system for engineering an osteochondral construct in the shape of an articular surface: preliminary results.

A tissue-engineered articular condyle could provide a new alternative approach to joint replacement. This study describes progress made towards engineering an articular condyle in vitro using human bone marrow stromal cells (hBMSCs) in a biphasic matrix. hBMSCs were transferred to a rat collagen-I hydrogel which was then pressed onto a bovine cancellous bone matrix. The gel/cell suspensions, each at a density of approximately 5 x 10(5)cells/ml containing fourth passage cells pressed into an adult human tibial condyle form using CT scan based moulds. The osteochondral constructs fabricated in vitro were stimulated in a bioreactor using cyclic compression and continuous perfusion. Penetration and cell distribution were demonstrated as homogeneous and cells were found to be viable after gel compression. The filamentous structure of the collagen fibres was more dense and homogeneous using compression. Mechanical tests showed a significant enhancement of primary matrix stability after initial compression. Stiffness was not observed to increase significantly over 7 days under loading in a bioreactor. The successful integration of mechanical stimulation in the tissue engineering process leads to an improvement in the structural and biomechanical properties of these tissues and offers new possibilities in the management of joint injuries and degenerative diseases. Remarkably, the stiffness was enhanced in our setting after initial compression of the construct in the glass cylinder without observing a negative influence on cell viability. Further studies need to clarify the influence of compression and various mechanical and hydrostatic stress patterns over different periods of time.

No mid-term difference in mosaicplasty in previously treated versus previously untreated patients with osteochondral lesions of the talus.

INTRODUCTION: Osteochondral transplantations, albeit technically challenging, appear promising not only in knee joint lesions, but also in the treatment of talus lesions. We hypothesized that in patients suffering osteochondral lesions of the talus, favorable outcomes are obtained in patients undergoing primary mosaicplasty as compared to patients undergoing secondary mosaicplasty. MATERIALS AND METHODS: Over a 3-year period (1998-2001), 14 patients (six male, eight female, median age 22 years) were treated with an autologous osteochondral transplantation of the talus. Eight patients were previously untreated (group I). Six patients had previous ankle procedures, such as microfracturing (group II). The median follow-up was 24 months and 100% complete at 12 months. The functional outcome was evaluated at least at 6 weeks, 12 weeks, and 1 year after surgery using pain on a visual analog scale (VAS) and sports activity was recorded at 1 year after surgery. In ten patients, magnetic resonance imaging (MRI) of the ankle was performed at 1 year after surgery (group I/II: 7/3). RESULTS: Overall ankle pain was decreased from 6.9 +/- 2.1 to 4.0 +/- 2.8 postoperatively. The mean knee pain for the donor knee was 2.6 +/- 2.4. We found no significant difference between the primary mosaicplasty group and the secondary mosaicplasty group with regard to pain. MRI scans of ten patients showed a complete incorporation of the osteochondral cylinders at 1 year after surgery. CONCLUSION: Favorable outcomes were obtained in patients undergoing primary mosaicplasty as compared to patients undergoing secondary mosaicplasty. We found no significant difference among patients with previous ankle surgery in contrast to those without, with a median 24-months follow-up.

Tissue engineering of tendons and ligaments by human bone marrow stromal cells in a liquid fibrin matrix in immunodeficient rats: results of a histologic study.

INTRODUCTION: The original complex structure and mechanical properties are not fully restored after ligament and tendon injuries. Due to their high proliferation rate and differentiation potential, Bone Marrow Stromal Cells (BMSC) are considered to be an ideal cell source for tissue engineering to optimize the healing process. Ideal matrices for tissue engineering of ligaments and tendons should allow for homogenous cell seeding and offer sufficient stability. MATERIAL AND METHODS: A mixture of human BMSC and liquid fibrin glue was injected into a standardized full-thickness window defect of the patellar tendon of immunodeficient rats (BMSC group). The histology of the tissue was analysed 10 and 20 days postoperatively and compared to four control groups. These groups consisted of a cohort with a mixture of human fibroblasts and fibrin glue, fibrin glue without cells, a defect group without treatment, and a group with uninjured patellar tendon tissue. RESULTS: Tendon defects in the BMSC group revealed dense collagen fibres and spindle-shaped cells, which were mainly orientated along the loading axis. Histologic sections of the control groups, especially of untreated defects and of defects filled with fibrin glue only, showed irregular patterns of cell distribution, irregular formed cell nucleoli and less tissue maturation. Compared to healthy tendon tissue, higher numbers of cells and less intense matrix staining was observed in the BMSC group. No ectopic bone or cartilage formation was observed in any specimen. CONCLUSIONS: Injection of human BMSC in a fibrin glue matrix appears to lead to more mature tissue formation with more regular patterns of cell distribution. Advantages of this "in-vivo" tissue engineering approach are a homogenous cell-matrix mixture in a well-known and approved biological matrix, and simple, minimally-invasive application by injection.

Rapid rehabilitation programme following sacral stress fracture in a long-distance running female athlete.

Stress fractures occur in normal bone due to mechanical overload by cyclic stress increasing the osteoclastic activity, thus facilitating weakening leading to fracture of bones. Long-distance running may lead to stress fractures of the mid- and distal tibia and of the metatarsal bones. Stress fractures to the sacrum are rare. Certain factors for stress fractures in runners have been identified, such as leg-length inequality, a high longitudinal arch of the foot, forefoot varus, and menstrual irregularities in case of female athlete triad. We report on a 22-year-old female runner (usually training 140 km/week) suffering a sacral fatigue-type fracture. The female athlete triad with eating disorders, dysmenorrhea, and osteopenia was ruled out. Sexual hormone blood samples proofed normal values. The diagnosis was performed using magnetic resonance imaging 2 weeks after the onset of buttock pain. A conservative treatment regimen was initiated with strict physical rest for the first 2 weeks, and then gradual increase of physical activity with 60-90 min of daily cycling and moderate 2 x 60 min cross-training. After another 2 weeks time, daily 60-90 min of walking, Nordic pole walking, and moderate strength training two times a week was performed. At 7 weeks running was started, gradually increased to 90 km/week without any pain. A rapid rehabilitation programme after sacral stress fractures involving low impact physical activity, such as Walking and Nordic pole walking, is applicable to female athletes after ruling out the female athlete triad.

Recurrent shoulder instability among athletes: changes in quality of life, sports activity, and muscle function following open repair.

BACKGROUND: Recurrent anterior shoulder instability is a disabling condition in young athletes with possibly underestimated impact on quality of life and sports activity. Commonly used clinical scoring systems do not reflect the impairment of quality of life and sports activity. It was our aim to assess the return to preinjury levels of quality of life and sports activity as well as the changes in muscle function among competitive and recreational athletes. HYPOTHESIS: Patients suffering from post-traumatic recurrent shoulder instability have to adopt their participation in sports and therefore discover a reduction in quality of life. Open stabilization procedures are able to improve shoulder function and to reduce recurrence rates. However, return to preinjury shoulder function is not guaranteed. STUDY DESIGN: Retrospective longitudinal cohort study on 19 consecutive athletes with recurrent, post-traumatic shoulder instability. All patients were treated with an open, capsulo-labral repair. The minimum follow-up was 24 months. METHODS: Life quality (SF12) and sports activity data (Athletic Shoulder Outcome Scoring System) were retrospectively collected for the time before injury (time 1) and for the time with recurrent instability (time 2). Two years after surgical stabilization (time 3), we followed our patients with different clinical outcome scores, rotator surface EMG measurement, isokinetic muscle strength testing, and a radiological evaluation. This design of a three-step follow-up allowed for calculating the impact on quality of life and sports activity following the injury. RESULTS: Two years after surgery, the clinical scoring systems revealed good-to-excellent results in all patients. Quality of life physical component summary remained diminished by 9.2% despite the surgical procedure and was therefore significantly lower as compared to preinjury levels (p < 0.05). Sports activity was also significantly lower at the time of follow-up (p < 0.05). In this specific procedure, external rotation was not impaired postoperatively. EMG testing showed an overall reduction of muscle activity, however not significant. Isokinetic muscle strength was significantly diminished for external rotation and shoulder abduction. CONCLUSIONS: Open reconstruction procedures for recurrent shoulder instability can restore shoulder function and stability to near-normal values. Despite good-to-excellent clinical results, there is a significant impairment of quality of life and sports activity 2 years after surgery. Muscle activity and muscle strength are diminished. Recurrent shoulder instability remains a disabling condition to the young athlete. Future strategies have to emphasize restoration of quality of life, sports activity, and muscle function.

[Arthroscopic partial meniscectomy].

OBJECTIVE: Excision of damaged meniscal tissue whereby the mechanical obstacles to joint movement are eliminated. As much functional, intact meniscal tissue should be retained as possible. Resection of only the bare minimum. INDICATIONS: Symptomatic, irreparable lesions of the meniscus due to trauma or degeneration. CONTRAINDICATIONS: Reparable lesions of the meniscus. Local skin affections. SURGICAL TECHNIQUE: Introduction of the arthroscope through an anterolateral or central portal. The instrument portal is positioned in accordance with the situation of the meniscal lesion to be treated. The tissue to be excised is either broken into fragments with different punches or resected en bloc. POSTOPERATIVE MANAGEMENT: Functional postoperative management without immobilization. Full loading on the leg. RESULTS: Very good and good clinical results can be achieved in the short and long term after arthroscopic partial meniscectomy. In a study by Burks et al., 88% of 146 patients with stable knee joints had a very good or good result 14.7 years after partial meniscectomy. 95% of 57 patients were satisfied or very satisfied with the result 12 years after partial medial meniscectomy. A degenerative meniscal tear, axial deformity, higher age, and anterior cruciate ligament insufficiency are factors associated with an increased rate of arthrosis in the long term.

Hinged external fixation and closed reduction for distal humerus fracture.

Elbow fractures are relatively rare in extremity injuries. Functional deficits often comprise the outcome. We report of a 77-year-old diabetic lady with a distal humerus fracture. She was treated with external fixation and closed reduction. Special emphasis was directed to early motion exercises. Follow-up after 1 year demonstrated a range of motion of 0-30-130 degrees for extension and flexion of the elbow joint. No neurovascular deficits were seen. The use of a hinged device was successful in re-establishing a good function. Although there are no earlier reports using this technique in acute treatment, we consider this strategy as an alternative option in carefully selected cases.

Modulation of proliferation and differentiation of human bone marrow stromal cells by fibroblast growth factor 2: potential implications for tissue engineering of tendons and ligaments.

Bone marrow stromal cells (BMSCs) play a central role in the repair and regeneration of mesenchymal tissues. For tissue engineering of ligaments and tendons, both stimulation of cell proliferation and differentiation with increased expression of essential extracellular matrix proteins and cytoskeletal elements are desirable. This study analyzes the effect of low-dose (3 ng/mL) fibroblast growth factor 2 (FGF-2) and high-dose FGF-2 (30 ng/mL) on proliferation (bromodeoxyuridine content, spectrophotometry), differentiation (transcription of collagen I, collagen III, fibronectin, elastin, alpha-smooth muscle actin, and vimentin, reverse transcription-polymerase chain reaction, and cell density and apoptosis (annexin V, fluorescence-activated cell sorting) of human BMSCs, and compares the results with those of a control group without FGF-2. Low-dose FGF-2 triggered a biphasic BMSC response: on day 7, cell proliferation reached its maximum and was significantly higher compared with the other groups. On days 14 or 28, collagen I, collagen III, fibronectin, and alpha- smooth muscle actin mRNA expression was significantly enhanced in the presence of low-dose FGF-2. In contrast, high-dose FGF-2 did not stimulate differentiation or proliferation. Vimentin mRNA was expressed only in cultures with low-dose and high-dose FGF-2 after 14 and 28 days. Cell density was significantly higher in cultures with low-dose FGF-2 compared with the group with high-dose FGF-2 on days 7, 14, and 28. The apoptosis rate remained stable, at a rather high level, in all groups. Microscopic investigation of the cell cultures with low-dose FGF-2 showed more homogeneous, dense, fibroblast-like, spindle-shaped cells with long cell processes compared with cultures with high-dose, or no FGF-2. Low-dose FGF-2 may be useful for tissue engineering of ligaments and tendons by increasing BMSC proliferation and stimulating mRNA expression of specific extracellular matrix proteins and cytoskeletal elements.

Alpha-smooth muscle actin containing contractile fibroblastic cells in human knee arthrofibrosis tissue. Winner of the AGA-DonJoy Award 2003.

INTRODUCTION: Primary arthrofibrosis is of major concern after joint trauma or knee ligament surgery. The underlying mechanism in detail remains unclear. Highly differentiated fibroblastic cells, so-called myofibroblasts, express the actin isoform alpha-smooth muscle actin (ASMA) and have been found to play a major role in tissue contraction during wound healing and organ fibrosis. We therefore studied the expression of myofibroblasts in human primary knee arthrofibrosis tissue. MATERIALS AND METHODS: Tissue samples were taken from the infrapatellar fat pad and intercondylar region of nine patients who underwent revision surgery due to arthrofibrosis after anterior cruciate ligament (ACL) reconstruction (study group). Control tissue was taken from five patients who underwent primary ACL reconstruction (control group I) and from eight patients, who underwent second-look arthroscopy after primary ACL reconstruction (control group II). ASMA containing fibroblasts were immunostained with a monoclonal antibody. Histomorphometry was performed for total cell amount, ASMA containing fibroblasts, and vessel cross-sections. RESULTS: The arthrofibrosis group showed a tenfold higher amount of ASMA containing myofibroblasts (23.4% vs. 2.3%) than in control group I. There was a significantly higher total cell count and lower vessel density than in control group I. Control group II showed an upregulation of myofibroblasts almost five times that in control group I; nevertheless there was no evidence of scar formation or tissue fibrosis. CONCLUSIONS: Myofibroblasts are responsible for scar tissue contraction during wound healing. In arthrofibrosis tissue fibroblast contraction may be involved in tissue fibrosis and contraction with consecutive loss of motion. We found that myofibroblasts are upregulated in arthrofibrosis tissue. ACL reconstruction itself caused an up regulation of myofibroblast content. Nevertheless these patients did not show any clinical or histological signs of arthrofibrosis. Thus it is reasonable to assume that the ratio of myofibroblasts and total cell amount in connective tissue are responsible for the onset of arthrofibrosis. Address the expression of this highly differentiated cell type may therefore present a target for future therapeutic interventions.

Cyclic mechanical strain induces NO production in human patellar tendon fibroblasts--a possible role for remodelling and pathological transformation.

The mechanism by which tendon fibroblasts can detect strain forces and respond to them is fairly unknown. Nitric oxide (NO) is a messenger molecule that among others can respond to shear stress in endothelial cells. Therefore, it was investigated whether cyclic mechanical strain induces NO in vitro in human patellar tendon fibroblasts. Human patellar tendon fibroblasts were cultured from remnants of patellar tendon transplants after reconstructive surgery. Fibroblasts were cultured on elastic silicone dishes. The cells were longitudinally strained (5%, 1 Hz) for 15' or 60'. As a control, no strain was applied. The experiments were finished after 0', 5', 15', and 30'. NO was determined using the Griess reaction. 15' strain showed at 0' and 5' 200% activation, which thereafter at 15' and 30' returned to normal levels. 60' strain showed a biphasic pattern. At 5' and 30', NO levels were increased to 175%. At 15', NO measurement displayed 120% increased levels. Mechanical strain induces NO production by tendon fibroblasts. Therefore, NO produced by tendon fibroblasts, as a response to alteration in their mechanical microenvironment, could modulate fibroblast function. The results of our study suggests that strain-related adaptive changes may, at least in part, be controlled by a process in which strain-related NO production from the fibroblast network may play a pivotal role. Moreover, these are basic findings that are important for further unravelling pathophysiology of tendon diseases.

Cyclic mechanical stretching of human patellar tendon fibroblasts: activation of JNK and modulation of apoptosis.

Accelerated rehabilitation after tendon, ligament and bone injuries is widely accepted to avoid adverse effects of immobilization. However, progressive rehabilitation may also lead to an excessive inflammatory soft tissue response and often leads to structural and functional problems such as excessive scarring. The equivalent at the molecular/cellular level is in part the regulation of the sensitive homeostasis between proliferation and apoptosis. However, little attention has been paid to this aspect of tendon pathogenesis. This study investigated the response profile of human tendon fibroblasts in terms of apoptosis and anticipated alteration of Jun N-terminal kinase (JNK) activation to cyclic mechanical stretching. Human tendon fibroblasts of six patients were stretched for 15 or 60 min with 1 Hz and an elongation of 5%. Activation of stress-activated protein kinase (SAPK)/JNK was measured by western blot analysis. Apoptotic cells were determined in the stretched cells and in controls by annexin-V staining and detection by flow cytometry. Additionally DNA laddering was determined by ligation-mediated (LM) polymerase chain reaction (PCR). Application of 15 and 60 min stretch increased activation of SAPK/JNK at a maximum after 60 min. However, JNK activation after the longer stretch period 50% less than after the shorter stretch period (15 min). The apoptosis rate was correspondingly increased after short stretch application but not after longer stretch. This might be caused by an inactivation of the activated JNKs by cell protection mechanisms. The findings suggest that mechanical stretching directly activates intracellular signaling pathways, which in turn induce apoptosis. The longer stretch period resulted in a decreased apoptotic rate due to development of stress tolerance. This might be caused by heat-shock protein mediated suppression of JNK activation. This novel observation is an important issue, as defined mechanical stretching, depending on its duration, modulates apoptosis and thus affects tendon remodeling.

Upper sympathetic trunk lesion after video-assisted fracture stabilization of the thoracic spine: a case report.

This case report draws attention to the upper sympathetic trunk lesion as a complication of video-assisted thoracic spine surgery. A 39-year-old man developed an upper sympathetic trunk lesion after right-sided thoracoscopic fracture stabilization of T5 and T6. Dizziness and reduced perspiration persisted at the most recent follow-up 8 months after surgery. This rare complication can be overlooked and remain undiagnosed. Diagnosis is based on clinical symptoms and neurologic examination. There are no treatment options. Symptoms can be bothersome for the patient and may persist. In the upper thoracic spine, the course of the sympathetic trunk lies in close proximity of the vertebral bodies; thus, care must be taken to avoid it when resecting the posterior parts of the vertebral body.