When math meets surgery: how to improve femoral interference screw alignment in ACL reconstruction. A cadaveric study.

Transtibial femoral tunnel drilling is still an alternative technique in ACL reconstruction. Femoral interference screw divergence is a potential pitfall associated with transtibial tunnel technique, as angles greater than 15° jeopardize graft fixation. Our mathematical model theorizes the proper degrees of knee flexion during femoral screw insertion and the correct screwdriver position to obtain a minimal divergence of the screw in the femoral tunnel. The cadaveric study confirms our method. Mathematical model: using rototranslation matrices, a correlation is demonstrated between the ACLtibial- guide angle, the knee flexion, and the screwdriver position. A theoretical minimal divergence between femoral interference screw and the femoral tunnel is obtainable following these assumptions: 1) knee hyperflexion during femoral screw insertion is obtained adding a flexion corresponding to the ACL-tibial-guide angle to the flexion while drilling the femoral tunnel; 2) screwdriver position (through the AM portal) is kept parallel to tibial plateau at a rotation of 15° medial to tibial sagittal plane. Cadaveric study: 24 cadaver knees were used. The transtibial tunnel was drilled with an 8 mm drill bit with the help of an ACL tibial guide set at 55°. To simulate femoral tunnel direction, a 2.4 mm K. wire was drilled through the femur with a transtibial 7 mm offset femoral drill guide. To simulate the femoral screw direction, a second 2.4 mm K. wire was drilled from the femoral entry point of the first wire through the femur, with a cannulated screwdriver. Screwdriver direction and knee flexion during the simulation were obtained following two different methods: GROUP A (mathematical model group, 12 knees), screwdriver direction and knee flexion were calculated following the mathematical model; in GROUP B (control group, 12 knees), knee hyperflexion and screwdriver medialization were manually obtained by a senior surgeon. The divergence between the femoral interference screw and the femoral tunnel was identified as the angle formed by the two wires, measured on the plane formed by the direction of the wires. Mean divergence angles between the K. wires were significantly different (p< 0.05) between the groups: GROUP 1 (mathematical rule): 7.25° (SD 2.2); GROUP 2 (free-hand technique): 17.3° (SD 2.9). Our study shows that a minimal divergence between the femoral tunnel and the screwdriver can be achieved simply by following a mathematical rule for correct intraoperative knee flexion and screwdriver position without the need for any specialized instrumentation. Namely, during femoral interference screw insertion through the anteromedial portal: 1) the correct knee flexion is the sum between the knee flexion angle while drilling the transtibial femoral tunnel AND the ACL tibial guide angle used during tibial tunnel drilling; 2) Correct screwdriver position is parallel to the tibial plateau, engaging the femoral tunnel with a position of 15° medial to tibial sagittal plane. This simple concept has clinical relevance in helping the surgeons in obtaining an optimal alignment between the femoral tunnel and the femoral interference screw during transtibial ACL reconstruction. Furthermore, following the assumptions of this study, a starting knee flexion angle around 70° during femoral tunnel drilling seems preferable for ACL reconstruction when the transtibial tunnel technique is used. Indeed, because ACL-tibial-guide angles range commonly from 50° to 60° and in vivo, the maximal intraoperative knee flexion attainable is 130°, a starting knee flexion around 70° is optimal to allows for adding flexion angles up to 60° before reaching the physiological limit value of 130°.

Hamstring grafts are tenogenic constructs for ACL reconstruction and Pulsed Electromagnetic Fields improve tendon specific markers expression. An in-vitro study.

Hamstring tendons represent one of the commonest autologous graft used during ACL reconstruction. The harvest of the tendon and the time of tendon processing on the operating table, together with the pretensioning maneuvers and the permanence out of the joint during the time of surgery, might impair tendon derived cells (TCs) viability. The aim of the study was: i) to assess the effective viability of the TCs at the end of the surgical procedure; ii) to investigate if TCs viability and the expression of tendon specific markers may be improved through exposure to prolonged pulsed electromagnetic fields (PEMF) similar to that of clinical practice. Remnants of semitendinosus and gracilis tendons (discarded at the end of the ACL reconstruction) were collected from 13 healthy donors. To isolate TCs, the tendon tissue was minced and digested enzymatically with 0.3% type I collagenase in DMEM with continuous agitation for 15 h at 37°C. The isolated nucleated cells were then plated at 5x103 cells/cm2 in a complete medium composed of DMEM, 10% fetal bovine serum, 50 U/ml Penicillin, 50 mg/ml Streptomycin, 2 mM L-glutamine, and supplemented with 5 ng/ml basic fibroblast growth factor (b-FGF). They were maintained at 37 °C in a humidified atmosphere with 5% CO2, changing culture medium every 3 days. When they reached 80-90% of confluence, the cells were detached by incubation with trypsin/EDTA and then cultured at a density of 5x103 cells/cm2. TCs were cultured in complete medium for 7, 14, 21 days (in chamber slides, to optimize the final immunofluorescence analysis). The following cell cultures were set up: i) TCs cultured with differentiation medium + exposure to PEMF 8 h/day; ii) TCs cultured with differentiation medium without exposure to PEMF. The stimulation with PEMF was generated by a pair of electrical coils, connected with the generator of pulsed electromagnetic fields (PEMF generator system IGEA, Carpi, Italy, intensity of magnetic field = 1.5 mT, frequency = 75 Hz). At day 0, day 7, day 14 and day 21 immunofluorescence analysis was performed to evaluate the expression of tendon specific markers (collagen type I, collagen type VI, scleraxis) and proliferative markers (PCNA, beta-catenin). The TCs from the hamstring tendon fragments at the end of the ACL reconstruction were alive and they expressed markers of proliferation and tendon phenotype at the end of the culture period. The TCs in the presence of PEMF 8h/day showed a greater production of collagen type I, collagen type VI and scleraxis than TCs cultured without PEMF (p<0.05). The expression of these markers increased from 7 to 21 days of culture. The expression of proliferative markers in the presence of PEMF stimulus was significantly lower (p<0.05) than that of TCs cultured without PEMF. Hamstring tendons are not simple "tenoconductive" scaffolds but biologic alive tenogenic constructs rich in cells that can sustain tenogenic behavior and tendon matrix synthesis. Prolonged exposure to PEMF improves their phenotype. Thus, from a clinical perspective, the use of PEMF may represent a possible future strategy to positively influence the early phase of graft remodeling and, ultimately, improve the ligamentization process. Following these concepts, further studies might also exploit the anabolic role of PEMF as an adjunctive postoperative strategy in different tendon pathologies.

Rehabilitation protocol after simultaneous anterior cruciate ligament reconstruction and high tibial osteotomy: introducing the concept of the individualized approach.

Postoperative rehabilitation after simultaneous anterior cruciate ligament reconstruction and opening wedge high tibial osteotomy is a complex concept. Different osteotomy techniques, extremely selected patients, high expectations in returning to previous sport activities, and the different individual physical profile and performances make traditional chronological criteria impractical and unfeasible. This study presents a novel rehabilitation in which functional objective criteria are considered the key factors for standardizing a 4-step protocol. Each step is "individualized", based on the patient's response to the healing processes and to the different training phases, allowing for a safe return to sports competitions. This definitively implies a strict collaboration between patient, surgeon, physician and physiotherapists, as well as thorough and detailed patient education. Due to the high versatility of these new rehabilitation concepts, the application of the "individualized" steps described in this study may be broadened to include different sports medicine knee injuries that may benefit from a specific, detailed and carefully patient-centered rehabilitation project.

Tips and tricks for writing a scientific manuscript.

An original scientific manuscript is the target for any researchers whose aim is to show the innovative results arising from the original intuitions that drove all their experiments. Time and patience are essential to decide how to present the data, how to conceive the tables and figures representing the main outcomes of the research, and how to read and mention the necessary references. Few basic rules may help in this difficult task. The first basic rule is: "do not follow the sequence of the paper". On the opposite, i) start writing the "Materials and Methods (or Patients and Methods when dealing with a clinical study)", ii) then write the "Results" section, iii) then, write the "Discussion" paragraph, in which the principal investigator explains the results and the innovations proposed, iv) then, write the "Introduction", which should be clear and concise. The last element to be written should be the "Abstract", which is the "interface" between the authors and the readers. The second basic rule is that any of the central chapters of the manuscript, i.e. "Materials and Methods" (MM), "Results" (R) and "Discussion" (D), should follow a methodical and sequential description of the topics in a "corresponding sequence of paragraphs". In other words, in the R and the D chapter sequence of the paragraphs should be linked to the sequence of the concepts described and discussed in the paragraphs of the MM chapter. Thus, a sequential description of concepts will be easily followed by the writers, facilitating both the authors in the organization of the data and the reader in finding a reasonable "answer" to all the aspects of the study mentioned in the MM chapter. In this article, these two rules are extensively described and several tips and tricks for each chapter are suggested to ease the composition of a scientific paper. Indeed, it may be possible to solve the complex problem of "writing a scientific paper" by means of separating it in main sections (chapters) and subsections (paragraphs) and dealing with them one by one. Naturally, this takes time and passion, but, as affirmed by Steve Jobs, "the only way to do great work is to love what you do".

One-step cartilage repair with minced chondral fragment on a composite scaffold: an in vitro human study at low oxygen tension.

Minced cartilage fragments are a viable cell source for one stage cartilage repair. However, the joint surface is a low oxygen tension microenvironment and little evidence is present in literature regarding the behaviour of cartilage fragments in this peculiar condition. The aim of the study is i) to verify if low oxygen tension could negatively influence chondrocyte outgrowth from cartilage fragments into a Hyaluronic-Acid(HA)/fibrin scaffold and ii) to evaluate its effects on the behaviour of migrating chondrocyte, compared to normoxic condition. A slight decrease in chondrocyte migration and proliferation was observed in low oxygen tension cultures. Conversely, an increase in the expression of SOX9, ß-catenin, HIFs, collagen-I and II (p<0.05) in migrating chondrocytes from low oxygen tension cultures was present. Thus, a long term- exposure at low oxygen tension seems to improve the chondrocytic phenotype expression of cell outgrowing from cartilage fragments onto a HA/fibrin scaffold.

Allogeneic Umbilical Cord-Derived Mesenchymal Stem Cells as a Potential Source for Cartilage and Bone Regeneration: An In Vitro Study.

Umbilical cord (UC) may represent an attractive cell source for allogeneic mesenchymal stem cell (MSC) therapy. The aim of this in vitro study is to investigate the chondrogenic and osteogenic potential of UC-MSCs grown onto tridimensional scaffolds, to identify a possible clinical relevance for an allogeneic use in cartilage and bone reconstructive surgery. Chondrogenic differentiation on scaffolds was confirmed at 4 weeks by the expression of sox-9 and type II collagen; low oxygen tension improved the expression of these chondrogenic markers. A similar trend was observed in pellet culture in terms of matrix (proteoglycan) production. Osteogenic differentiation on bone-graft-substitute was also confirmed after 30 days of culture by the expression of osteocalcin and RunX-2. Cells grown in the hypertrophic medium showed at 5 weeks safranin o-positive stain and an increased CbFa1 expression, confirming the ability of these cells to undergo hypertrophy. These results suggest that the UC-MSCs isolated from minced umbilical cords may represent a valuable allogeneic cell population, which might have a potential for orthopaedic tissue engineering such as the on-demand cell delivery using chondrogenic, osteogenic, and endochondral scaffold. This study may have a clinical relevance as a future hypothetical option for allogeneic single-stage cartilage repair and bone regeneration.

Tranexamic acid effects on cartilage and synovial tissue: an in vitro study for a possible safe intra-articular use.

The possible toxic effects of intra-articular tranexamic acid (TA) are still debated. The aim of this study was to evaluate TA effects on human cartilage fragments and synovial biopsies. Explant culture of minced articular cartilage underwent prolonged TA exposure. Histological analysis, immunofluorescence and colorimetric assay for quantification of s-GAG and DNA were performed at the end term. Synoviocytes were cultured for 48h in presence of TA. Light microscopy and flow cytometry analysis were performed at the end of the exposure to TA and one week after the treatment. TA exposure did not influence i) the chondrocyte outgrowth and migration, ii) the expression of chondrogenic and proliferative markers and iii) the s-GAG/DNA ratio. TA treatment did not affect synoviocytes' morphology and treated cells were phenotypically similar to control cells. This study demonstrated that TA does not negatively affect chondrocytes and synoviocytes cultured in vitro. Thus, our findings may be clinically relevant in order to validate the intra-articular TA administration during orthopedic procedures.

Human cartilage fragments in a composite scaffold for single-stage cartilage repair: an in vitro study of the chondrocyte migration and the influence of TGF-ß1 and G-CSF.

PURPOSE: Minced chondral fragments are becoming popular as a source of cells for cartilage repair, as a growing interest is developing towards one-stage procedures to treat cartilage lesions. The purpose of this study is to (A) compare cell outgrowth from cartilage fragments of adult and young donors using two different types of scaffolds and (B) evaluate the influence of transforming-growth-factor-ß1 (TGF-ß1) and granulocyte colony-stimulating factor (G-CSF) on chondrocyte behaviour. METHODS: In part (A) cartilage fragments from adult and young donors were either loaded onto an HA-derivative injectable paste scaffold or onto an HA-derivative membrane scaffold. Construct sections were then examined for cell counting after 1, 2 and 3 months. In part (B) only membrane scaffolds were prepared using cartilage fragments from young donors. Constructs were cultured either in standard growth medium or in the presence of specific growth factors, such as TGF-ß1 or G-CSF or TGF-ß1 + G-CSF. After 1 month, construct sections were examined for cell counting. Expression of chondrocyte markers (SOX9, CD151, CD49c) and proliferative markers (ß-catenin, PCNA) was assessed using immunofluorescence techniques, both in unstimulated construct sections and in cells from unstimulated and stimulated construct cultures. RESULTS: Part (A): histological analysis showed age-dependent and time-dependent chondrocyte migration. A significant difference (p < 0.05) was observed between young and older donors at the same time point. No difference was detected between the two types of scaffolds within the same group at the same time point. Part (B): after 1 month, the number of migrating cells/area significantly increased due to exposure to TGF-ß1 and/or G-CSF (p < 0.05). Immunofluorescence revealed that outgrowing cells from unstimulated scaffold sections were positive for SOX9, CD151, CD49c and G-CSF receptor. Immunofluorescence of cells from construct cultures showed an increase in ß-catenin in all stimulated groups and an increased PCNA expression in G-CSF-exposed cultures (p < 0.05). CONCLUSION: Outgrowing cells may represent a subset of chondrocytes undergoing a phenotypic shift towards a proliferative state. TGF-ß1, and to a greater extent G-CSF, may accelerate this outgrowth. The clinical relevance of this study may involve a potential future clinical application of scaffolds preloaded with growth factors as an additional coating for chondral fragments. Indeed, a controlled delivery of G-CSF, widely employed in various clinical settings, might improve the repair process driven by minced human cartilage fragments during one-stage cartilage repair.

Minced umbilical cord fragments as a source of cells for orthopaedic tissue engineering: an in vitro study.

A promising approach for musculoskeletal repair and regeneration is mesenchymal-stem-cell- (MSC-)based tissue engineering. The aim of the study was to apply a simple protocol based on mincing the umbilical cord (UC), without removing any blood vessels or using any enzymatic digestion, to rapidly obtain an adequate number of multipotent UC-MSCs. We obtained, at passage 1 (P1), a mean value of 4, 2 × 10(6) cells (SD 0,4) from each UC. At immunophenotypic characterization, cells were positive for CD73, CD90, CD105, CD44, CD29, and HLA-I and negative for CD34 and HLA-class II, with a subpopulation negative for both HLA-I and HLA-II. Newborn origin and multilineage potential toward bone, fat, cartilage, and muscle was demonstrated. Telomere length was similar to that of bone-marrow (BM) MSCs from young donors. The results suggest that simply collecting UC-MSCs at P1 from minced umbilical cord fragments allows to achieve a valuable population of cells suitable for orthopaedic tissue engineering.

One-step osteochondral repair with cartilage fragments in a composite scaffold.

PURPOSE: This study proposes a single-step therapeutic approach for osteochondral defects using autologous cartilage fragments loaded onto a scaffold composed of a hyaluronic acid (HA) derivative, human fibrin glue (FG) and autologous platelet-rich-plasma (PRP), in a rabbit model. The aim is to demonstrate the in vitro outgrowth of chondrocytes from cartilage fragments and the in vivo formation of a functional repair tissue. METHODS: In vitro: minced articular cartilage was loaded onto two different types of scaffold (paste or membrane) according to two different HA preparations (injectable HA-derivative or HA-derivative felt). In vivo: trochlear osteochondral defects were created in 50 adult rabbits, which were then assigned to 5 different treatment groups: cartilage fragments loaded onto membrane scaffolds with FG (Group 1) or without FG (Group 2); membrane scaffolds alone with FG (Group 3) or without FG (Group 4); empty defects (Group 5). Membrane scaffolds were used "in vivo" for simpler preparation and better adhesive properties. Repair processes were evaluated histologically and by immunohistochemistry at 1, 3, and 6 months. RESULTS: An in vitro time-dependent cell outgrowth from cartilage fragments was observed with both types of scaffolds. At 6 months, in vivo, cartilage fragment-loaded scaffolds induced significantly better repair tissue than the scaffold alone using histological scoring. Repair in Group 2 was superior to that in any of the control groups (p < 0.05). CONCLUSION: Autologous cartilage fragments loaded onto an HA felt/FG/PRP-scaffold provided an efficient cell source, and allowed for an improvement of the repair process of ostechondral defects in a rabbit model. Human FG, however, hampered the rabbit healing process. These results may have clinical relevance as they show the potential of a novel one-stage repair technique for osteochondral defects.

Treatment of medial and posteromedial knee instability: indications, techniques, and review of the results.

Injuries of the posteromedial corner of the knee are relatively common. These can be isolated or combined with other ligament lesions. In some cases the treatment of postero-medial corner injuries is controversial. After a brief description of the anatomy and biomechanics of the medial side of the knee, this paper reviews the indications for isolated and multiligamentous medial/posteromedial corner injuries both in the acute and in the chronic setting. In addition, the most common surgical techniques for repair and reconstruction are described in addition to outcomes based upon a review of the literature.

Influence of timing and oral anticoagulant/antiplatelet therapy on outcomes of patients affected by hip fractures.

BACKGROUND: Patients undergoing surgical procedures are usually asked to discontinue any anticoagulant/antiplatelet therapy and delay surgery for at least 5 days to reduce the risk of major bleeding and spinal hematoma. AIM: The purpose of this study was to determine if this strategy is suitable for patients on anticoagulant/antiplatelet therapy affected by a hip fracture, evaluating the effect of anticoagulant/antiplatelet therapy and surgical timing on mortality and complication rates for patients affected by a hip fracture. PATIENTS AND METHODS: We performed an observational study on patients referring to our hospital for a hip fracture. We evaluated patients on warfarin, ticlopidine, and aspirin therapy matched to patients not on anticoagulant or antiplatelet therapy, out of 875 consecutive patients treated for a hip fracture in a 5-year period. Blood loss, blood transfusions, length of hospitalization, walking ability, complications, and mortality at 1 year of follow-up were recorded. Kruskal-Wallis, Mann-Whitney U, and logistic regression statistical tests were performed. RESULTS: Patients on warfarin therapy operated more than 5 days after admission showed significantly higher complication and mortality rates compared to all other patients. Two critical factors were identified: warfarin therapy and excessive time to surgery; these factors are not significant if taken alone, while they become a high-risk factor if taken together. CONCLUSION: The "discontinue drug, and delay surgery" strategy is not suitable for patients on anticoagulant (warfarin) therapy affected by a hip fracture.