We have developed plasmonic fibrin-based hydrogels that incorporate gold nanoparticles which transduce incident near-infrared (NIR) light into heat. Human adenovirus serotype type-5 vectors encoding a firefly luciferase (fLuc) coding sequence driven by a heat-inducible promoter were incorporated into the hydrogels. Transmission electronic microscopic analysis revealed that the adenoviral vectors were associated to the fibrin fibers. In vitro experiments in which human cells were cultured with plasmonic hydrogels showed that the adenoviral vectors can diffuse from the hydrogels, transduce the cells, and stimulate heat-induced transgene expression upon NIR irradiation. The hydrogels were implanted in 4.2 mm drill hole defects generated in the humerus of male rabbits. Three days after implantation, the defects were NIR-irradiated. Six h later, the animals were euthanized and samples from the bone defect zone were processed for immunohistochemical analyses using a specific fLuc antibody. The results showed strong expression of fLuc in tissues surrounding the implants of NIR-irradiated rabbits, while non- irradiated animals exhibited negligible expression. We next aimed to use the temperature increase to induce the production of transgenic bone morphogenetic protein 6 (BMP-6), using safe gene switches that can provide tighter control of in vivo transgene expression than heat-inducible promoters. These switches are only activated by heat in the presence of rapamycin and maintain a high level of targeted transgene expression for several days after heat activation. Adenoviral vectors encoding the safe switches that control the expression of BMP-6 were incorporated to the composites. The resulting NIR-responsive hydrogels were implanted in the bone defects generated in rabbits and used as a platform to transduce host cells, generate local hyperthermia and stimulate BMP-6 production.

Acknowledgements: This research was supported by grants RTI2018-095159-B-I00 and PID2021-126325OB-I00 (MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”), by grant P2022/BMD- 7406 (Regional Government of Madrid). M.A.L-J. is the recipient of predoctoral fellowship PRE2019-090430 (MCIN/AEI/10.13039/501100011033).

To compare the incidence of Bone Cement Implantation Syndrome (BCIS), perioperative thromboembolic events and mortality in patients with a femoral neck fracture (FNF) treated with a hybrid total hip arthroplasty (THA) without intraoperative unfractioned heparin (UFH) (control) versus a group of patients who received intraoperative UFH before femoral cementation.

We retrospectively reviewed 273 patients who underwent hybrid THA due to a FNF between 2015 and 2020. We compared a group of 139 patients without intraoperative administration of UFH (group A) with 134 patients who underwent THA with intraoperative administration of 10 UI/kg UFH (group B). UFH indication was dependent on surgeon´s preference. We assessed the advent of BCIS and 30-day thromboembolic events, as well as 90-day and 1-year mortality.

BCIS was observed in 51 cases (18%), defined as Grade 1 (O2% < 94% or fall in systolic blood pressure of 20% to 40%) in 37 cases (13%) and Grade 2 (O2% < 88% or fall in systolic blood pressure of > 40%) in 14 cases (5%). Forty-seven BCIS (35%) were observed in the group that received UFH and 4 BCIS (3%) in the control group (p <0.001). Multivariate regression model showed that intraoperative UFH (OR=18, CI95% 6–52) and consumption of oral anticoagulants (OR=3.3, CI95% 1–10) had an increased risk of developing BCIS. Five patients developed a pulmonary embolism in the UFH group while 2 patients presented this complication in the non UFH group (p=0.231). Mortality was 1% for both groups at 90 days PO (p= 0.98), 2% at 1 year for group A and 3% for group B (p =0.38).

BCIS in our series was 18%. We found a paradoxically 17-fold significant increase of BCIS with the use of UFH. Heparin did not prevent BCIS, thromboembolic events and mortality in this group of patients.

Bone-regenerative and biocompatible materials are indicated for the regeneration of bone lost in periodontology and maxillofacial surgery. Bio-Oss is a natural bone mineral for bone grafting of bovine origin and the most common used in this kind of interventions¹. Sil-Oss is a new synthetic nanostructured monetite-based material that is reabsorbed at the same time that is replaced by new bone tissue ². Bacterial infection is one of the complications related to this kind of material. Streptococcus oralis is the most associated oral infecting pathogen to oral surgery³ and Staphylococcus aureus is the most common infecting pathogen to maxillofacial non-oral interventions⁴. Here we evaluated bacterial adherence of two of the most common infecting bacteria of this kind of biomaterial: S. oralis and S. aureus, on Bio-Oss and Sil-Oss.

S. oralis ATCC 9811 and S. aureus 15981 strains were used. Bacterial adherence was evaluated using the modified previously described protocol of Kinnari et al.⁵ that was adapted to our biomaterial. The quantification was performed by the drop plate method⁶. The statistical data were analyzed by pairwise comparisons using the nonparametric Mann-Whitney test with a level of statistical significance of p<0.05. Values are cited and represented as medians.

Bacterial adherence decreased significantly on Sil-Oss compared to Bio-Oss. S. oralis ATCC 9811 adherence was between 11 and 13-fold less on Sil-Oss compared to Bio-oss. In the case of S. aureus15981, the adherence was between 4 and 6-fold less on Sil-Oss compared to Bio-Oss.

Sil-Oss nanostructured monetite-based biomaterial could be considered as a promising biomaterial to be used for the regeneration of bone defects since the bacterial adherence on it is lower than on another currently used material.

Objectives

To determine the limits of spinal displacement before the onset of neurophysiological changes during spinal surgery. Assessing if the type of force applied or the section of the adjacent nerve roots increases the tolerance to displacement.

Aim

To determine whether delayed diagnosis (lapse from initial symptoms to the beginning of treatment) has influence on the possibilities of crossing the physis by the tumour, and/or on the outcome in pediatric patients with high grade metaphyseal osteosarcoma.

Background: The presence of bacteria forming biofilms or prior antimicrobial use has been shown to reduce the sensitivity of the standard technique (PT cultures) in patients with infection of orthopedic implants. Culturing fluid resulting from sonication (FRS) of prosthesis could improve the microbiologic diagnosis.

Objective: To analyze the diagnostic validity of culturing FRS of different orthopedic implants and PT culture

Methods: Between Jan 2007 and Apr 2008, patients undergoing knee or hip prosthesis removal, and those with ostheosyntesis or spinal instrumentation removal, were prospectively included (44 hip prosthesis, 63 knee prosthesis, 91 osteosynthesis and 14 spinal instrumentations). 5 PT specimens were collected for culture. Removed implants were sonicated during 5 min. (40Hz). Both, PT and FRS, were inoculated in aerobic agar (Chocolate Polyvitex), anaerobic agar (Schaedler + 5% blood) and in thioglycolat, for 7 days. Positive culture cut-off was defined as growing of > 5 CFU. Clinical diagnosis of prosthetic-joint infection was made as commonly accepted. Previous antimicrobial therapy was assessed. Diagnostic validity was calculated for both culturing methods. Sensitivity of methods was compared by Chi-square test (SPSS 15.0).

Results: 212 cases were included. Diagnostic of infection was made in 17 hip prosthesis (THA), 20 knee prosthesis (TKA), 24 osteosynthesis (OS) and 6 spinal fusions (SI).

Tissue culture was positive in 9 THA, 11 TKA 18 OS and 4 SI. Sonication culture was positive in 14 THA, 18TKA, 23 Os and 6 SI.

Tissue culture: Sensibility: THA53%, TKA 55%, OS 75% and SI 66%. Specificity: THA 96%, TKA 100%, OS 96%, SI 100%

Sonications: Sensibility: THA 82%, TKA 90%, OS 95% and SI 100%. Specificity: THA 96%, TKA 100%, OS 92%, SI 100%

Statistical differences favoring sonication were found in sensitivity in knee arthroplasty and osteosynthesis implants. 6 patients received antibiotics for > 7 days before implant was removed. Sonication culture was positive in 4 of them whereas only one standard culture yielded positive.

Conclusions: FRS cultures are more sensitive than PT cultures. Sensitivity of the method depends on which device is evaluated. Sonication also improves sensitivity of culture after preoperative antimicrobial therapy.

Introduction and purpose: Distal radius fractures often affect the joint surface; their reduction is difficult and may be incomplete. In these cases the use of an arthroscope may help reconstruct the joint surface of the radius and allow the diagnosis of ligament injuries. The purpose of this study is to analyze the results of this type of fractures by means of this technique.

Materials and methods: Between November 2001 and January 2007 we reduced 24 fractures of the distal extremity of the radius that involved the joint surface with arthroscopic control. The mean age of the patients was 36 years (range: 21–55). We used Barbieri and Geissler’s classification. We recorded the approach route, arthroscopic ports, ligament injuries observed and complications. Also both radiological and functional results were assessed.

Results: In 18 of the 24 patients some sort of ligamentous or osteochondral lesion was found (lunate-pisiform ligament, scaphoid-lunate ligament or triangular cartilage). All achieved union after a mean period of 8 weeks. By means of x-rays we measured a mean intraarticular step-off of 0.29 mm and a mean interfragment distance of 0.5 mm. Joint balance and force were normal at the end of rehabilitation in 22 out of 24 cases.

Conclusion: The use of arthroscopy in intraarticular fractures of the distal extremity of the radius is a technique that helps achieve a more accurate reduction of the joint surface and allows the repair of lesions which would have been overlooked during traditional surgery without decreasing union rate or functional results.

Introduction and purpose: The most commonly found degenerative changes in the wrist can be included in two basic patterns of advanced carpal collapse: On the one hand scapholunate advanced collapse (SLAC) and on the other scaphoid nonunion advanced collapse (SNAC). To treat this collapse, Watson described the so-called four-corner arthrodesis, which includes the lunate, capitate, pisiform and hamate bones. The aim of this study is to assess the results obtained using fixation with a Spider plate.

Materials and methods: In this study we included a series of 20 patients that underwent 4-corner arthrodesis with a Spider plate. These cases had stage II or III advanced degeneration of the wrist both SLAC and SNAC. We have also used this technique for other indications such as osteochondral lesions of the head of the capitate, mediocarpal arthritis or mediocarpal instability.

Results: Mean follow-up was 16 (7–25) months. An important decrease in pain was seen in all cases and postoperative values were as follows: palmar flexion, 38° (range: 12–46); dorsal flexion, 30° (range: 12–45); radial deviation, 12° (range: 0–16); ulnar deviation, 24° (range: 15–40). An increase in fist force was seen after surgery. The arthrodesis healed in all cases, with a slight decrease in carpal height index after surgery.

Conclusions: This surgical technique has allowed us to obtain good results determined clinically and by means of X-rays, as well as early motion after surgery.

Introduction: Congenital kyphosis is an uncommon deformity caused by failure of the vertebral bodies to form and/or segment. It is treated surgically. Our purpose is to confirm whether the treatment protocols established years ago are still valid and to assess the benefits of improved implants.

Materials and methods: Between 1985 and 2003, 24 patients underwent surgery in La Paz Hospital. They were classified into three groups: < 5 years (8 p), 6–12 (6 p) and > 13 (10 p). The minimum follow-up was 2 years (2–14). The procedures were posterior or circumferential spinal fusion, with or without instrumentation, and corrective osteotomy. Complications were evaluated radiographically.

Results: In the first group posterior spinal fusion was performed in six patients and circumferential in two, with a correction rate of 55%. In the second group instrumented circumferential spinal fusion was performed in three cases and instrumented posterior in three (30% correction). In the third group eight of the ten patients underwent instrumented anteroposterior spinal fusion (osteotomy in five) and the correction rate was 45%. Complications: 3 pseudoarthrosis, 1 DVT, 2 infections and 3 failed implants.

Conclusions: Congenital kyphosis can be controlled at any age, although early surgery is best. Gradual correction occurs after poster spinal fusion in children and instrumentation prevents revision of the fusion and prolonged immobilisation. Persons over the age of 5 with type I kyphosis usually require circumferential spinal fusion.

Introduction: Osteoarthritis is the most common joint disease in the world. Biochemical and genetic factors as well as mechanical stress contribute to lesions in the cartilage. The present study analyses the effect of b-Endorphin on the cells of articular cartilage.

Materials and methods: We used rat articular cartilage for the study. After tripsinizing the cartilage and isolating the chondrocytes the cells were cultured in a culture medium. B-Endorphin was dissolved in the culture medium at concentrations of 1 and 10 mM. Only the culture medium was added to the control wells. Naloxone 1 mM was added for co-treatment with b-Endorphin and naloxone. Thirty minutes later, b-Endorphin was added, thus blocking its receptors.

Results: We studied the effect of this procedure on chondrocytes’ proliferating activity and on the proteoglycan synthesis of the extracellular matrix. An increase was observed in the incorporation of 3H-Thymidine, which in turn reflected an increase in the chondrocytes’ proliferating activity. In addition, 35S incorporation analyses were made of cultures which assessed proteoglycan synthesis which showed an increase in the extracellular-matrix forming activity. Differences between the groups with b-endorphin, b-endorphin + naloxone and the control group were found to be highly significant (p< 0.01).

Conclusions: B-endorphin has a stimulating effect upon chondrocytes and proteoglycans present in the extracellular matrix in culture. These stimulating effects are mediated by the interaction with a specific opioid receptor, present in the articular cartilage cells. It may be conceived that trophic stimulation of cartilage cells in the early stages of the disease might partly mitigate the loss of joint surface.

Introduction and purpose: This study analyses the long-term results and the polyethylene wear rate of a first-generation hemispherical porous shell.

Materials and methods: 40 Tri-Lock shells were analyzed associated to an ACS (DePuy) PE insert implanted between 1988 and 1992. The PE had been gamma sterilized in air. The mean follow-up until revision or last control was 9.3 years (range: 3.1–15.0). PE wear was assessed by means of image digitalization with an Auto-CAD 14R software after 6 weeks (position zero), 6 and 12 months and, then, once a year. All cases were associated to a Profile stem.

Results: All shells showed themselves to be radiographically osseointegrated. 7 cases had acetabular osteolysis (Kaplan-Meier survival: 74.1% at 13 years). The appearance of osteolysis was related to a higher average wear rate (p=0.0021) and a higher wear rate at the end of follow-up (p=0.0147). 11 cases showed a breakage of the PE (Kaplan-Meier survival: 61.69+29.9% at 13 years). These breakages appeared on average after 60.1 months. The distance between the axis of the femoral head and that of the shell on the initial radiograph (position zero or initial settling) was 0.6018 in cases with breakage and 0.2338 in cases with no breakage (p=0.009). PE breakage was related to a higher mean wear rate (p< 0.0001) and the verticalization of the shell (p=0.0016).

Conclusions: Although all Tri-Lock cups were osseoin-tegrated, the breakage of the ACS insert was an usual finding, which was related with a higher initial settling of the PE, a higher mean wear rate and the verticalization of the shell.

Introduction and Objectives: This is a retrospective radiographic study of results of surgical correction of thoracolumbar and King I scoliosis using segmental instrumentation.

Materials and Methods: This study includes 44 patients (41 female, 3 male) with an average age of 16.8 years (12-40) and 5.9 years average progression. The number of instrumented levels was 5.1 (4–7). Curve magnitude, T1–S1 imbalance, and the angles of the instrumented zone were measured using teleradiographic studies with an anteroposterior view. Thoracic kyphosis and lumbar lordosis were measured in the sagittal plane, and the thoracic and lumbar regions were measured in the instrumented area.

Results: On the anteroposterior view, average magnitude of principal preoperative curve, postoperative curve, and final result was 48°, 11.9°, and 14.7°, respectively. A final correction of 69.3% was obtained. T1–S1 imbalance improved from an initial 2.1cm to 1.9cm postoperatively and a final result of 0.5cm. On the lateral view, preoperative, postoperative, and final thoracic kyphosis were 29.5°, 27.8°, and 30.4°, respectively. Average figures for lumbar lordosis were 59.2°, 55.6°, and 61.1°. The instrumented thoracic zone went from 0.8° kyphosis preoperatively to 4.7° final kyphosis, and the lumbar area of instrumentation went from 9.7° preoperative lordosis to a final angle of 10.4°.

Discussion and Conclusions: In our experience, correction of thoracolumbar and King I scoliosis using anterior instrumentation has given good results, obtaining an initial 75% correction of the principal curve and an average loss of only 3° on follow-up. In the sagittal plane, there is no loss of kyphosis and lordosis, both of which are within normal physiological ranges. Thoracic kyphosis was increased 3.9° in the instrumented zone, and although instrumented lordosis did not improve, a kyphotic effect was observed.

Introduction and Objectives: This study examines the need for transfusion in trauma surgery for subcapital fractures of the femur (SFF) in a tertiary hospital and analyzes possible predictive factors.

Materials and Methods: A prospective study was done using patients requiring surgical treatment for SFF in the year 1998. Patients younger than 65 years, those with hemopathies, and patients undergoing anticoagulant therapy were excluded from the study. The following variables were analysed: age, sex, haemogram at time of admission (haemoglobin [Hb], haematocrit [Hct], mean corpuscular volume [MCV], mean corpuscular haemoglobin [MCH], anisocytosis [area under the curve or AUC]; preoperative and postoperative Hb and Hct (preoperative values only if surgery did not take place within 48 hours of admission); time to surgical intervention, transfusions, and use of blood derivatives.

Results: The study included 75 patients operated on for SFF. These included 18 with B1 fractures, 8 with B2, and 49 with B3 based on AO classification. There were 12 males and 63 females, and average age was 81 years (standard deviation [SD]=8). Average values upon admission were as follows: Hb 128 (SD=23) g/l, Hct 39% (SD=6%), MCH 30.3 pg, MCV 91.4 fL, and AUC 14.3%. Average time to surgical intervention was 5 days (SD=2.8). Types of surgical intervention included 23 screws (31%) and 52 partial hip prostheses (69%). Preoperative average haemogram values were Hb 119 (SD=12) g/l and Hct 36% (SD=4%). Forty-one patients (55%) received transfusions of concentrated red cells. Of these, 8 (11%) were preoperative, 8 (11%) were perioperative, and 31 (41%) were in the immediate postoperative period. Gender, age, MCV, MCH, and time to surgery were not found to be related to the need for transfusion. On the other hand, correlations were found between Hb at time of admission, postoperative Hb, anisocytosis, type of fracture, and type of surgical intervention. The only variable independently-related to the need for transfusion was Hb at time of admission.

Discussion and Conclusions: In spite of the urgent nature of these cases, the results of this study suggest a need for further studies designed to improve the haematologic parameters for these elderly patients upon admission, such as the adoption of less aggressive measures and the establishment of a blood storage system for high-risk patients, with the aim of reducing the need for transfusions and the inherent risks of allogeneic blood transfusions.