Mechanical and strain behaviour of human Achilles tendon during in vitro testing to failure.

The Achilles tendon is the strongest tendon in the human body but its mechanical behaviour during failure has been little studied and the basis of its high tensile strength has not been elucidated in detail. In the present study, healthy, human, Achilles tendons were loaded to failure in an anatomically authentic fashion while the local deformation and strains were studied in real time, with very high precision, using digital image correlation (DIC). The values determined for the strength of the Achilles tendon were at the high end of those reported in the literature, consistent with the absence of a pre-existing tendinopathy in the samples, as determined by careful gross inspection and histology. Early in the loading cycle, the proximal region of the tendon accumulated high lateral strains while longitudinal strains remained low. However, immediately before rupture, the mid-substance of the Achilles tendon, its weakest part, started to show high longitudinal strains. These new insights advance the understanding of the mechanical behaviour of tendons as they are stretched to failure.

Enthesis: not the same in each localisation - a molecular, histological and biomechanical study.

The interphase between tendon and bone consists of a highly specialised tissue called enthesis. Typically, the enthesis is described as a succession of four different zones: tendon, non-mineralised fibrocartilage, mineralised fibrocartilage and bone. However, the microstructure of the entheses, cellular composition and mechanical properties vary depending on their anatomical location. The present study aimed to characterise three of the most relevant sites of enthesis injury in a rat model: the patellar tendon, the Achilles tendon and the supraspinatus enthesis, in terms of biomechanics, histology and genetic expression. The patellar enthesis presented the highest ultimate load and lowest stiffness of the three, while the supraspinatus was the weakest and stiffest. The histological characterisation revealed key differences at the insertion site for each enthesis. The patellar enthesis showed a large cartilaginous area at the tendon-to-bone interphase whilst this interphase was smaller in the supraspinatus entheses samples. Furthermore, the Achilles tendon enthesis displayed a more abrupt transition from tendon to bone. Additionally, each enthesis exhibited a particular and distinct pattern of expression of tenogenic, chondrogenic and osteogenic markers. This study provided valuable insights for a better understanding of the three entheses at relevant anatomical sites. Moreover, the larger cross-sectional area of the patellar enthesis, the strong mechanical properties and the easier surgical access to this location led to the conclusion that the patellar tendon enthesis site could be most suitable for the development of a preclinical model for general enthesis regeneration studies in rats.

Osteoinduction and -conduction through absorbable bone substitute materials based on calcium sulfate: in vivo biological behavior in a rabbit model.

Calcium sulfate (CS) can be used as an antibiotically impregnated bone substitute in a variety of clinical constellations. Antibiotically loaded bone substitutes find specific application in orthopedic and trauma surgery to prevent or treat bone infections especially in relation to open bone defects. However, its use as a structural bone graft reveals some concerns due to its fast biodegradation. The addition of calcium carbonate and tripalmitin makes CS formulations more resistant to resorption leaving bone time to form during a prolonged degradation process. The aim of the present study was the evaluation of biocompatibility and degradation properties of newly formulated antibiotically impregnated CS preparations. Three different types of CS bone substitute beads were implanted into the tibial metaphysis of rabbits (CS dihydrate with tripalmitin, containing gentamicin (Group A) or vancomycin (Group B); Group C: tobramycin-loaded CS hemihydrate). Examinations were performed by means of x-ray, micro-computed tomography (micro-CT) and histology after 4, 6, 8 and 12 weeks. Regarding biocompatibility of the formulations, no adverse reactions were observed. Histology showed formation of vital bone cells attached directly to the implanted materials, while no cytotoxic effect in the surrounding of the beads was detected. All CS preparations showed osteogenesis associated to implanted material. Osteoblasts attached directly to the implant surface and revealed osteoid production, osteocytes were found in newly mineralized bone. Group C implants (Osteoset®) were subject to quick degradation within 4 weeks, after 6-8 weeks there were only minor remnants with little osteogenesis demonstrated by histological investigations. Group A implants (Herafill®-G) revealed similar degradation within atleast 12 weeks. In contrast, group B implants (CaSO4-V) were still detectable after 12 weeks with the presence of implant-associated osteogenesis atlatest follow-up. In all of these preparations, giant cells were found during implant degradation on surface and inside of resorption lacunae. None of the analyzed CS preparations triggered contact activation. All implants demonstrated excellent biocompatibility, with implants of Group A and B showing excellent features as osteoconductive and -inductive scaffolds able to improve mechanical stability.

Association between volume of severely injured patients and mortality in German trauma hospitals.

BACKGROUND: The issue of patient volume related to trauma outcomes is still under debate. This study aimed to investigate the relationship between number of severely injured patients treated and mortality in German trauma hospitals. METHODS: This was a retrospective analysis of the TraumaRegister DGU® (2009-2013). The inclusion criteria were patients in Germany with a severe trauma injury (defined as Injury Severity Score (ISS) of at least 16), and with data available for calculation of Revised Injury Severity Classification (RISC) II score. Patients transferred early were excluded. Outcome analysis (observed versus expected mortality obtained by RISC-II score) was performed by logistic regression. RESULTS: A total of 39,289 patients were included. Mean(s.d.) age was 49.9(21.8) years, 27,824 (71.3 per cent) were male, mean(s.d.) ISS was 27.2(11.6) and 10,826 (29.2 per cent) had a Glasgow Coma Scale score below 8. Of 587 hospitals, 98 were level I, 235 level II and 254 level III trauma centres. There was no significant difference between observed and expected mortality in volume subgroups with 40-59, 60-79 or 80-99 patients treated per year. In the subgroups with 1-19 and 20-39 patients per year, the observed mortality was significantly greater than the predicted mortality (P < 0.050). High-volume hospitals had an absolute difference between observed and predicted mortality, suggesting a survival benefit of about 1 per cent compared with low-volume hospitals. Adjusted logistic regression analysis (including hospital level) identified patient volume as an independent positive predictor of survival (odds ratio 1.001 per patient per year; P = 0.038). CONCLUSION: The hospital volume of severely injured patients was identified as an independent predictor of survival. A clear cut-off value for volume could not be established, but at least 40 patients per year per hospital appeared beneficial for survival.

[Synovial biomarkers for differential diagnosis of painful arthroplasty]. / Synoviale Biomarker für die Differenzialdiagnostik der schmerzhaften Endoprothese.

BACKGROUND: The diagnosis and treatment of periprosthetic joint infection (PJI) remain true clinical challenges. PJI diminishes therapeutic success, causes dissatisfaction for the patient and medical staff, and often requires extensive surgical revision(s). At the present time, an extensive multimodal algorithmic approach is used to avoid time- and cost-consuming diagnostic aberrations. However, especially in the case of the frequent and clinically most relevant "low-grade" PJI, the current diagnostic "gold standard" has reached its limits. EVALUATION: Synovial biomarkers are thought to close this diagnostic gap, hopefully enabling the safe differentiation among aseptic, (chronic) septic, implant allergy-related and the arthrofibrotic genesis of symptomatic arthroplasty. Therefore, joint aspiration for obtaining synovial fluid is preferred over surgical synovial tissue biopsy because of the faster results, greater practicability, greater patient safety, and lower costs. In addition to the parameters synovial IL-6, CRP, and leukocyte esterase, novel biomarkers such as antimicrobial peptides and other proinflammatory cytokines are currently highlighted because of their very high to excellent diagnostic accuracy. CONCLUSION: Independent multicenter validation studies are required to show whether a set of different innovative synovial fluid biomarkers rather than a few single parameters is favorable for a safe "one-stop shop" differential diagnosis of PJI.

Constitutive and inducible co-expression systems for non-viral osteoinductive gene therapy.

Tissue regenerative gene therapy requires expression strategies that deliver therapeutic effective amounts of transgenes. As physiological expression patterns are more complex than high-level expression of a singular therapeutic gene, we aimed at constitutive or inducible co-expression of 2 transgenes simultaneously. Co-expression of human bone morphogenetic protein 2 and 7 (BMP2/7) from constitutively expressing and doxycycline inducible plasmids was evaluated in vitro in C2C12 cells with osteocalcin reporter gene assays and standard assays for osteogenic differentiation. The constitutive systems were additionally tested in an in vivo pilot for ectopic bone formation after repeated naked DNA injection to murine muscle tissue. Inductor controlled differentiation was demonstrated in vitro for inducible co-expression. Both co-expression systems, inducible and constitutive, achieved significantly better osteogenic differentiation than single factor expression. The potency of the constitutive co-expression systems was dependent on relative expression cassette topology. In vivo, ectopic bone formation was demonstrated in 6/13 animals (46% bone formation efficacy) at days 14 and 28 in hind limb muscles as proven by in vivo µCT and histological evaluation. In vitro findings demonstrated that the devised single vector BMP2/7 co-expression strategy mediates superior osteoinduction, can be applied in an inductor controlled fashion and that its efficiency is dependent on expression cassette topology. In vivo results indicatethatco-expression of BMP2/7 applied by non-viral naked DNA gene transfer effectively mediates bone formation without the application of biomaterials, cells or recombinant growth factors, offering a promising alternative to current treatment strategies with potential for clinical translation in the future.

[Cytokines as biomarkers in polytraumatized patients]. / Zytokine als Marker bei Polytrauma.

BACKGROUND: Multiple trauma can lead to posttraumatic complications such as systemic inflammatory response syndrome (SIRS), multiple organ dysfunction syndrome (MODS), and sepsis. Currently, these complications are monitored using clinical and organ-specific parameters. The immune system is activated by trauma. Cytokines, which are the messenger molecules of this system, can be determined in serum. Furthermore, they are associated with the intensity of the inflammatory and anti-inflammatory reactions. AIM: This review describes clinical studies that measured cytokines such as TNF-α, IL-1ß, IL-6, IL-8, and IL-10 to prognosticate posttraumatic complications. On the other hand, IL-6 can be helpful in deciding which primary operation to perform, i.e., external fixator or intramedullary nail. Moreover, IL-6 indicates the strength of the immune reaction. Thereby, it may help in determining the optimal time for secondary surgery.

[Diagnostic biomarkers in traumatic brain injury]. / Diagnostische Biomarker des Schädel-Hirn-Traumas.

BACKGROUND: Despite advances in medicine in head trauma management, traumatic brain injury (TBI) still remains a serious health concern, affecting people regardless of age. It is a leading cause of morbidity and mortality particularly in children and young adults. Therefore, studies are being carried out to try to establish reliable biomarkers to improve the accuracy of TBI diagnosis and associated secondary pathologies. METHODS: Implementation of valid TBI biomarkers could possibly reduce the necessity to use computed cranial tomography (CCT), especially in patients suffering from mild TBI to rule out intracranial bleeding. AIM: This review provides a critical assessment of biomarkers currently under investigation and their clinical value for the diagnosis, treatment and outcome prediction of TBI.

Systemic inflammatory effects of traumatic brain injury, femur fracture, and shock: an experimental murine polytrauma model.

OBJECTIVE: Despite broad research in neurotrauma and shock, little is known on systemic inflammatory effects of the clinically most relevant combined polytrauma. Experimental investigation in an animal model may provide relevant insight for therapeutic strategies. We describe the effects of a combined injury with respect to lymphocyte population and cytokine activation. METHODS: 45 male C57BL/6J mice (mean weight 27 g) were anesthetized with ketamine/xylazine. Animals were subjected to a weight drop closed traumatic brain injury (WD-TBI), a femoral fracture and hemorrhagic shock (FX-SH). Animals were subdivided into WD-TBI, FX-SH and combined trauma (CO-TX) groups. Subjects were sacrificed at 96 h. Blood was analysed for cytokines and by flow cytometry for lymphocyte populations. RESULTS: Mortality was 8%, 13% and 47% for FX-SH, WD-TBI and CO-TX groups (P < 0.05). TNFα (11/13/139 for FX-SH/WD-TBI/CO-TX; P < 0.05), CCL2 (78/96/227; P < 0.05) and IL-6 (16/48/281; P = 0.05) showed significant increases in the CO-TX group. Lymphocyte populations results for FX-SH, WD-TBI and CO-TX were: CD-4 (31/21/22; P = n.s.), CD-8 (7/28/34, P < 0.05), CD-4-CD-8 (11/12/18; P = n.s.), CD-56 (36/7/8; P < 0.05). CONCLUSION: This study shows that a combination of closed TBI and femur-fracture/ shock results in an increase of the humoral inflammation. More attention to combined injury models in inflammation research is indicated.

Aprotinin and classic wound drainage are unnecessary in total hip replacement - a prospective randomized trial.

BACKGROUND: Classic wound drainage is still common in hip replacement but its benefit is doubtful. The role of systemic administration of proteinase inhibitors like aprotinin to avoid perioperative blood loss is still unclear. PATIENTS AND METHODS: In a prospective randomized trial, the perioperative blood loss in alloplastic hip replacement under the influence of proteinase inhibitor (aprotinin, Trasylol®) using wound drainage as well as compression treatment alone were compared. 80 patients were prospectively randomized in 4 arms. Patients received either aprotinin or placebo during surgery as well as drainage or targeted external wound compression. RESULTS: Observing the "drug therapy" aprotinin had no effect on the intra- or postoperative blood loss (p>0.05), a trend to lower postoperative hemoglobin decline was found, but without significance. Thrombosis occurred in neither the aprotinin nor in the placebo group. Two patients had a severe allergic drug reaction and were excluded from the study. Under "non drug therapy" with compression therapy and wound drainage a significant difference in blood loss was found (p<0.001). The blood loss was higher under the wound drainage. There was no influence on the infection rate. Yet we could observe increased bruising under the sole external compression treatment. CONCLUSION: The administration of aprotinin did not achieve the desired reduction of perioperative blood loss. Hence, costs and two severe allergic drug reactions in our study represent arguments against its use in regular treatment. Furthermore, it seems that wound drainage is neglectable in hip replacement and can be substituted by a sole compression treatment.

Defining the variety of cell types in developing and adult human kidneys by single-cell RNA sequencing.

The kidney is among the most complex organs in terms of the variety of cell types. The cellular complexity of human kidneys is not fully unraveled and this challenge is further complicated by the existence of multiple progenitor pools and differentiation pathways. Researchers disagree on the variety of renal cell types due to a lack of research providing a comprehensive picture and the challenge to translate findings between species. To find an answer to the number of human renal cell types, we discuss research that used single-cell RNA sequencing on developing and adult human kidney tissue and compares these findings to the literature of the pre-single-cell RNA sequencing era. We find that these publications show major steps towards the discovery of novel cell types and intermediate cell stages as well as complex molecular signatures and lineage pathways throughout development. The variety of cell types remains variable in the single-cell literature, which is due to the limitations of the technique. Nevertheless, our analysis approaches an accumulated number of 41 identified cell populations of renal lineage and 32 of non-renal lineage in the adult kidney, and there is certainly much more to discover. There is still a need for a consensus on a variety of definitions and standards in single-cell RNA sequencing research, such as the definition of what is a cell type. Nevertheless, this early-stage research already proves to be of significant impact for both clinical and regenerative medicine, and shows potential to enhance the generation of sophisticated in vitro kidney tissue.

Evaluation of the tissue toxicity of antiseptics by the hen's egg test on the chorioallantoic membrane (HETCAM).

BACKGROUND: Antiseptics are frequently used for the prophylaxis and treatment of local infections of chronic wounds. Whereas local antiseptics in general have a positive effect on wound healing an uncritical use may impair wound healing due to toxic side effects. OBJECTIVE: We sought to assess the vascular irritation potential of different antiseptic solutions and ointments commonly used for short and long term application as a measure of tissue toxicity. METHOD: The vascular irritation was evaluated by the hen's egg test (HET) on the chorioallantoic membrane (CAM). The effects on the vessels of a mucous membrane were directly assessed by stereomicroscopic observation in vivo. RESULTS: Severe CAM irritation was observed after short-term applications of 1% octenidin-2HCl (Octenisept), 72% isopropanol (Cutasept), 0.35% chloroxylenol (Dettol) and 10% PVP-I ointment (Betaisodona). Medium irritations were observed for 10% PVP-I solution (Betaisodona), 3% lysosomal PVP-I ointment (Repithel), 1.8% cadexomer-iodine ointment (Iodosorb) and 1% cadexomer-iodine pellets (Iodosorb). Finally, slight irritations were observed for 1% PVP-I solution (Betaisodona), 0.1% polyhexanid plus betain (Prontosan) and 1% silver-sulfadiazine ointment (Flammazine), whereas 0.04% polyhexanid solution (Lavanid), washings from sterile maggots of Lucilia sericata and filtrated enzymes from Clostridium histolyticum (Iruxol-N) showed no effects of irritation. In the long-term approaches, no vascular irritations were found for polyhexanid, washings from Lucilia sericata and enzyme filtrations from Clostridium histolyticum. CONCLUSION: The vascular injuries caused by the studied antiseptics are an indirect indicator of their tissue toxicity. Strikingly, even therapeutic substances, which have been regarded as safe in their application for the treatment of chronic wounds in clinical studies, showed severe irritations on the CAM. We suggest that agents with no or low irritation potential on the CAM should be preferred in the clinical practice in order to obtain optimal results.

Biphasic calcium phosphate ceramics in small bone defects: potential influence of carrier substances and bone marrow on bone regeneration.

OBJECTIVES: Synthetic calcium phosphate bone substitutes such as hydroxyapatite (HA), beta-tricalcium phosphate (beta-TCP) or mixtures are alternatives to autogenous bone grafts. TricOs T((R)) and Collagraft((R)) are resorbable bone substitutes consisting of biphasic calcium phosphate and a bioactive matrix. Both products have a similar HA to beta-TCP ratio, but differ by their matrix. It was the aim of this study to determine the influence of matrix and autologous bone marrow on bone regeneration in a rabbit femoral condyle model. MATERIAL AND METHODS: A critical-sized bicortical channel with a diameter of 4.5 mm was drilled through the femoral condyles in male New Zealand rabbits. Collagraft((R)) with bone marrow harvested from the posterior iliac crest or TricOs T((R)) with and without bone marrow was introduced into the defect. Rabbits were euthanized 8 weeks later. The percentage of newly formed bone was determined by micro-computed tomography. RESULTS: There was no significant difference between bone ingrowth at 8 weeks. Thus, TricOs T((R)) without bone marrow showed similar bone ingrowth as Collagraft((R)) with bone marrow. Furthermore, no increase of bone ingrowth could be achieved by adding bone marrow to TricOs T((R)) in the present setting. CONCLUSION: Both bone substitutes showed similar bone ingrowth in this investigation. Using TricOs T((R)) without bone marrow could avoid donor site morbidity due to harvesting of bone marrow. Further prospective clinical trials will be needed to investigate this approach.

Starch-poly-epsilon-caprolactone microparticles reduce the needed amount of BMP-2.

BMP-2 is currently administered clinically using collagen matrices often requiring large amounts of BMP-2 due to burst release over a short period of time. We developed and tested a novel injectable drug delivery system consisting of starch-poly-epsilon-caprolactone microparticles for inducing osteogenesis and requiring smaller amounts of BMP-2. We evaluated BMP-2 encapsulation efficiency and the in vitro release profile by enzyme-linked immunosorbent assay. BMP-2 was rapidly released during the first 12 hours, followed by sustained release for up to 10 days. We then evaluated the osteogenic potential of dexamethasone (standard osteogenic induction agent) and BMP-2 after incorporation and during release using an osteo/myoblast cell line (C2C12). Alkaline phosphatase activity was increased by released BMP-2. Mineralization occurred after stimulation with BMP-2-loaded microparticles. A luciferase assay for osteocalcin promoter activity showed high levels of activity upon treatment with BMP-2-loaded microparticles. In contrast, no osteogenesis occurred in C2C12 cells using dexamethasone-loaded microparticles. However, human adipose stem cells exposed to the microparticles produced high amounts of alkaline phosphatase. The data suggest starch-poly-epsilon-caprolactone microparticles are suitable carriers for the incorporation and controlled release of glucocorticoids and growth factors. Specifically, they reduce the amount of BMP-2 needed and allow more sustained osteogenic effects.

Phenotypic shift of human amniotic epithelial cells in culture is associated with reduced osteogenic differentiation in vitro.

BACKGROUND: Amniotic membrane is a highly promising cell source for tissue engineering. Being part of the placenta, this tissue is abundantly available. It can be processed easily to yield large amounts of epithelial and mesenchymal cells that have shown broad differentiation potential. For tissue-engineering purposes, cells may be applied either directly after isolation from the tissue or after a period of in vitro expansion to obtain higher cell numbers. In order to investigate the advantages and drawbacks of these strategies we compared freshly isolated and cultivated human amniotic epithelial cells (hAEC) regarding their surface antigen (Ag) expression profile and osteogenic differentiation capacity. METHODS: Expression of surface Ag that are characteristic for mesenchymal stromal and embryonic stem cells was analyzed by flow cytometry. Different protocols for osteogenic and adipogenic differentiation were compared. RESULTS: We have demonstrated that expression of surface Ag changes dramatically during cultivation of hAEC. While not or only weakly expressed on primary isolates, the mesenchymal markers CD13, CD44, CD49e, CD54, CD90 and CD105 are strongly up-regulated during in vitro propagation. In contrast, expression of the embryonic markers TRA-1-60 and TRA-1-81, but not SSEA-4, rapidly decreases upon cultivation. This phenotypic shift is associated with a reduction in osteogenic differentiation. DISCUSSION: Our results suggest that phenotypic alterations of hAEC during in vitro cultivation might be responsible for a functional reduction of the differentiation potential, which has to be considered for the potential application of these cells in regenerative medicine.

Systemic effects of isolated brain injury: an experimental animal study.

OBJECTIVE: Although various experimental works of neurotrauma research are performed, little attention has been paid to the concomitant systemic changes following isolated traumatic brain injury (TBI). Such investigations seem to be a prerequisite condition for evaluation of experimental drugs, which may diminish the secondary damage following TBI. We describe histopathologic findings of the lung, liver, spleen and kidney 96 hours following an experimental TBI. METHODS: Ten male C57BI/6 mice were subjected to a controlled cortical impact (CCI) over the left parietotemporal cortex using rounded-tip impounder for application of a standardized brain injury. Subjects were killed 96 hours following trauma. Brain, lung, liver, kidney and spleen were preserved for morphologic examinations. RESULTS: Moderate histopathologic changes were evident in the lung and liver. The kidney and spleen seem not to be affected by the trauma regarding our examination. CONCLUSION: The findings of this study show that even isolated TBI can lead to a migration of immunocompetent cells to peripheral organs potentially leading to dysfunctions of peripheral organs to various extents. More attention to peripheral organs during experimental TBI research is indicated.

Validity of S-100 B in patients after brain radiation.

BACKGROUND: S-100B is a calcium binding acute phase protein and a potential biomarker for brain injury. In prior studies elevated plasma S-100B levels were detected in stroke and severe head trauma. The aim of this study was to evaluate whether S-100 B is elevated during cerebral radiotherapy and whether that is associated with adverse outcomes. MATERIAL AND METHODS: In this prospective pilot study, 45 patients (25 males, 20 females, median age 58 (17-81)) underwent cerebral radiation therapy because of a primary or metastaic cerebral malignancy. 39 patients were included in the evaluation. 6 patients died during the study period. S-100 plasma concentrations were measured with an electrochemiluminescence immunoassay on admission and weekly during radiation therapy for the duration of 6 weeks. In 10 healthy young volunteers (5 males, 5 females, median age 32 (28-36)) S-100 B plasma levels were measured weekly for 6 weeks as a negative control. Furthermore, in an active control 10 patients (4 males, 6 females, median age 68 (64-76)) with stroke (7 = major stroke, 3 = lacunar infarct) S- 100 B plasma levels were measured for 7 consecutive days after the event. RESULTS: During radiotherapy S-100 B plasma concentrations increased from median baseline values of 0.030 microg/l to 0.044 microg/l. For the time of radiation therapy most patients showed a mild increase, but absolute plasma values were still within the normal range. In the control group of healthy volunteers S-100 B remained unchanged. In stroke patients S-100 B increased to maximum values of 1.7 microg/l three days after the event. In the 3 patients with lacunar infarcts no increase of S-100 B levels could be detected. CONCLUSION: Brain irradiation leads to a mild increase of S-100 B plasma levels. However, the absolute rise was far weaker compared to that seen in major brain injuries.

Osteoinduction in human fat-derived stem cells by recombinant human bone morphogenetic protein-2 produced in Escherichia coli.

Bioactive recombinant human bone morphogenetic protein-2 (rhBMP-2) was obtained using Escherichia coli pET-25b expression system: 55 mg purified rhBMP-2 were achieved per g cell dry wt, with up to 95% purity. In murine C2C12 cell line, rhBMP-2 induced an increase in the transcription of Smads and of osteogenic markers Runx2/Cbfa1 and Osterix, measured by semi-quantitative RT-PCR. Bioassays performed in human fat-derived stem cells showed an increased activity of the early osteogenic marker, alkaline phosphatase, and the absence of cytotoxicity.

Patient satisfaction after hook plate treatment of bony avulsion fracture of the distal phalanges.

BACKGROUND: Bony avulsion fractures of the distal phalanges can result in mallet finger deformity if not treated appropriately. Therefore, only minimally displaced fractures can be treated conservatively with a good outcome, as dislocation occurs very often. Several surgical treatment options have been developed during the past decades. Data concerning the recently developed hook plate are promising. So far, no data concerning the subjective satisfaction with this method have been published. Therefore, we have analyzed the outcome after hook plate implantation using a self-assessment score, which focuses also on subjective parameters and satisfaction. METHODS: Standardized questionnaires (self-assessment scores and SF-36 questionnaire) were sent to each patient treated with a hook plate due to fracture of the distal phalanx, type Doyle IVb and IVc. Clinical data were evaluated according to the medical record. Scores given per question range from 0 to 10, 10 is the worst and 0 the best outcome. RESULTS: From 69 patients treated, 38 (58%) were enrolled. The whole collective (n = 38) reached a score of 39.7 ± 28.7 points, while men had slightly better results. Men (n = 24) achieved 37.3 ± 27.9 points, women (n = 14) 43.9 ± 30.7 points. Women had significantly better results when analyzed later than 12 months after surgery (52.1 ± 27.9 vs. 29.1 ± 32.8), whereas no changes could be detected in the male group (37.1 ± 29.9 vs. 37.4 ± 27.6). Overall, men were slightly more satisfied than women. Most satisfaction was found regarding pain and fine motor skills (0-0.46 points). Esthetic aspect and nail deformities (3.65 points average) led to the highest dissatisfaction. No differences in the SF 36 score could be detected. CONCLUSIONS: The hook plate is not only a convenient method but it also results in high patient satisfaction. Nail deformities are challenging; however, with increasing experience of the surgeon they decrease. SF 36 score is not an appropriate testing tool for this problem.