Mechanical and histological properties of native medial menisci compared to allograph medial menisci in the osteoarthritic knee.

This study was designed to provide information on how the menisci change over the course of osteoarthritis, particularly with regard to their mechanical properties. The aim was to determine the difference between healthy menisci (fresh frozen meniscal transplants) and menisci harvested during total knee arthroplasty. The latter allows the grading of age-related and osteoarthritic changes in the menisci on macroscopic and microscopic levels. A total of 10 menisci from arthritic knee joints (medial) harvested during total knee arthroplasty were used and compared with 10 medial fresh frozen meniscal transplants. The mechanical measurements were carried out on a Mach-1 testing machine using indentation testing to determine the instantaneous modulus and the thickness of the menisci. The specimens were then embedded in paraffin, sectioned on a microtome, and stained with hematoxylin-eosin and safranin-O. All measurements were divided into the anterior horn, pars intermedia, and posterior horn. There was no significant difference in the instantaneous modulus for the posterior horn in the fresh frozen menisci with 0.27 ± 0.1 MPa compared to the arthritic menisci with 0.18 ± 0.03 MPa. No significant difference could be determined for the meniscus thicknesses. There was a significant difference in the safranin-O staining. There were also significant differences in the Pauli score: the arthrosis menisci showed a sum score that was, on average, four times higher than the sum score of the fresh frozen menisci. In the present study, it could be shown very well that there are significant differences in the mechanical properties as well as in the macroscopic and histopathological scores, such as the Pauli score, between the fresh frozen meniscus allografts considered healthy and osteoarthritic menisci resulting from total knee arthroplasty. With a degradation score of 3 (Pauli), the instantaneous modulus was reduced by more than 50% compared to healthy controls. More importantly, however, the fresh frozen menisci only show a grade 2 when converting the sum values into grades, where a grade 2 indicates slight degeneration. This is interesting because fresh frozen meniscus transplants were always considered healthy in previous publications and should, therefore, actually have a grade 1.

Internal Rotation Measurement of the Knee with Polymer-Based Capacitive Strain Gauges versus Mechanical Rotation Measurement Taking Gender Differences into Account: A Comparative Analysis.

With the conventional mechanical rotation measurement of joints, only static measurements are possible with the patient at rest. In the future, it would be interesting to carry out dynamic rotation measurements, for example, when walking or participating in sports. Therefore, a measurement method with an elastic polymer-based capacitive measuring system was developed and validated. In our system, the measurement setup was comprised of a capacitive strain gauge made from a polymer, which was connected to a flexible printed circuit board. The electronics integrated into the printed circuit board allowed data acquisition and transmission. As the sensor strip was elongated, it caused a change in the spacing between the strain gauge's electrodes, leading to a modification in capacitance. Consequently, this alteration in capacitance enabled the measurement of strain. The measurement system was affixed to the knee by adhering the sensor to the skin in alignment with the anterolateral ligament (ALL), allowing the lower part of the sensor (made of silicone) and the circuit board to be in direct contact with the knee's surface. It is important to note that the sensor should be attached without any prior stretching. To validate the system, an in vivo test was conducted on 10 healthy volunteers. The dorsiflexion of the ankle was set at 2 Nm using a torque meter to eliminate any rotational laxity in the ankle. A strain gauge sensor was affixed to the Gerdii's tubercle along the course of the anterolateral ligament, just beneath the lateral epicondyle of the thigh. In three successive measurements, the internal rotation of the foot and, consequently, the lower leg was quantified with a 2 Nm torque. The alteration in the stretch mark's length was then compared to the measured internal rotation angle using the static measuring device. A statistically significant difference between genders emerged in the internal rotation range of the knee (p = 0.003), with female participants displaying a greater range of rotation compared to their male counterparts. The polymer-based capacitive strain gauge exhibited consistent linearity across all measurements, remaining within the sensor's initial 20% strain range. The comparison between length change and the knee's internal rotation angle revealed a positive correlation (r = 1, p < 0.01). The current study shows that elastic polymer-based capacitive strain gauges are a reliable instrument for the internal rotation measurement of the knee. This will allow dynamic measurements in the future under many different settings. In addition, significant gender differences in the internal rotation angle were seen.

Effect of Vancomycin, Gentamicin and Clindamycin on Cartilage Cells In Vitro.

BACKGROUND: The treatment of grafts with vancomycin for ligament reconstruction in knee surgery is the current standard. However, high antibiotic concentrations have chondrotoxic effects. PURPOSE: To test the chondrotoxicity of clindamycin, gentamicin and vancomycin in comparable concentrations. In vitro and in vivo effective concentrations hugely vary from drug to drug. To allow for comparisons between these three commonly used antibiotics, the concentration ranges frequently used in orthopedic surgical settings were tested. STUDY DESIGN: Controlled laboratory study. METHODS: Human cartilage from 10 specimens was used to isolate chondrocytes. The chondrocytes were treated with clindamycin (1 mg/mL and 0.5 mg/mL), gentamicin (10 mg/mL and 5 mg/mL) or vancomycin (10 mg/mL and 5 mg/mL), at concentrations used for preoperative infection prophylaxis in ligament surgery. Observations were taken over a period of 7 days. A control of untreated chondrocytes was included. To test the chondrotoxicity, a lactate dehydrogenase (LDH) test and a water-soluble tetrazolium salt (WST-1) assay were performed on days 1, 3 and 7. In addition, microscopic examinations were performed after fluorescence staining of the cells at the same time intervals. RESULTS: All samples showed a reasonable vitality of the cartilage cells after 72 h. However, clindamycin and gentamicin both showed higher chondrotoxicity in all investigations compared to vancomycin. After a period of 7 days, only chondrocytes treated with vancomycin showed reasonable vitality. CONCLUSIONS: The preoperative treatment of ligament grafts with vancomycin is the most reasonable method for infection prophylaxis, in accordance with the current study results regarding chondrotoxicity; however, clindamycin and gentamicin cover a wider anti-bacterial spectrum. CLINICAL RELEVANCE: The prophylactic antibiotic treatment of ligament grafts at concentrations of 5 mg/mL or 10 mg/mL vancomycin is justifiable and reasonable. In specific cases, even the use of gentamicin and clindamycin is appropriate.

Digital measurement of anterolateral knee laxity using strain sensors.

PURPOSE: The ambition of the research group was to develop a sensor-based system that allowed the transfer of results with strain sensors applied to the knee joint. This system was to be validated in comparison to the current static mechanical measurement system. For this purpose, the internal rotation laxity of the knee joint was measured, as it is relevant for anterolateral knee laxity and anterior cruciate ligament (ACL) injury. METHODS: This is a noninvasive measurement method using strain sensors which are applied to the skin in the course of the anterolateral ligament. The subjects were placed in supine position. First the left and then the right leg were clinically examined sequentially and documented by means of an examination form. 11 subjects aged 21 to 45 years, 5 women and 6 men were examined. Internal rotation of the lower leg was performed with a torque of 2 Nm at a knee flexion angle of 30°. RESULTS: Comparison of correlation between length change and internal knee rotation angle showed a strong positive correlation (r = 1, p < 0.01). Whereas females showed a significant higher laxity vs. males (p = 0.003). CONCLUSIONS: The present study showed that the capacitive strain sensors can be used for reproducible measurement of anterolateral knee laxity. In contrast to the previous static systems, a dynamic measurement will be possible by this method in the future.

Effect of 20 µm thin ceramic coatings of hydroxyapatite, bioglass, GB14 and Beta-Tricalciumphosphate with copper on the biomechanical stability of femoral implants.

In the present work, we test four thin coatings for titanium implants, namely, bioglass, GB14, Beta-Tricalciumphosphate (ß-TCP) and hydroxyapatite (HA) with and without incorporated copper ions for their osteointegrative capacity. A rabbit drill hole model for time intervals up to 24 weeks was used in this study. Implant fixation was evaluated by measuring shear strength of the implant/bone interface. Quantitative histological analysis was performed for the measurements of bone contact area. Implants with and without copper ions were compared after 24 weeks. Thin coatings of GB14, HA or TCP on titanium implants demonstrated high shear strength during the entire test period of up to 24 weeks. Results confirmed osteointegrative properties of the coatings and did not reveal any negative effect of copper ions on osteointegration. The integration of copper in degradable osteoconductive coatings with a thickness of approx. 20 µm represents a promising method of achieving antibacterial shielding during the entire period of bone healing while at the same time improving osteointegration of the implants.

A human bone infection organ model for biomaterial research.

The aim of this work was to establish an organ model for staphylococcal infection of human bone samples and to investigate the influence and efficacy of a microporous ß-tricalcium phosphate ceramic (ß-TCP, RMS Foundation) loaded with hydrogels (alginate, alginate-di-aldehyde (ADA)-gelatin) and clindamycin on infected human bone tissue over a period of 28 days. For this purpose, human tibia plateaus, collected during total knee replacement surgery, were used as a source of bone material. Samples were infected with S. aureus ATCC29213 and treated with differently loaded ß-TCP composites (alginate +/- clindamycin, ADA-gelatin +/- clindamycin, unloaded). The loading of the composites was carried out by means of a flow chamber. The infection was observed for 28 days, quantifying bacteria in the medium and the osseus material on day 1, 7, 14, 21 and 28. All samples were histologically processed for bone vitality evaluation. Bone infection could be consistently performed within the organ model. In addition, a strong reduction in bacterial counts was recorded in the groups treated with ADA-gelatin + clindamycin and alginate + clindamycin, while the bacterial count in the control groups remained constant. No significant differences between groups could be observed in the number of lacunae filled with osteocytes suggesting no differences in bone vitality among groups. In an ex-vivo human bone infection model, over a period of 28 days bacterial growth could be reduced by treatment with ADA-Gel + CLI and ALG + CLI -releasing ß-TCP composites. This could be relevant for its clinical use. Further work will be necessary to improve the loading of ß-TCP and the bone infection organ model itself. STATEMENT OF SIGNIFICANCE: The common treatment of bone infections is debridement and systemic administration of antibiotics. In some cases, antibiotic-containing carriers are already used, but these must be removed again. Our work is intended to show another treatment option. The scaffold we have developed, made of a calcium phosphate ceramic and a hydrogel as the active substance carrier, can, in addition to releasing the active substance, also assume a load-bearing function of the bone and is biodegradable. In addition, the model we developed can also be used for the analysis and treatment of bone infections other than those of the musculoskeletal system. More importantly, it can also serve as a substitute for previously used animal experiments.

Knee Scores of Patients with Non-Lateral Compartmental Knee Osteoarthritis Undergoing Mobile, Fixed-Bearing Unicompartmental Knee and Total Knee Arthroplasties: A Randomized Controlled Trial.

OBJECTIVE: To evaluate knee scores and clinical efficacies of patients with non-lateral unicompartmental knee osteoarthritis (OA) who randomly underwent mobile-bearing (MB) unicompartmental knee arthroplasty (UKA), fixed-bearing (FB) UKA, and total knee arthroplasty (TKA). METHODS: From September 2015 to February 2017, a prospective, randomized, parallel, single-center trial of 180 patients (78 males and 102 females; 63.3 ± 6.9 years) with non-lateral compartmental knee OA was performed in the first author-affiliated hospital. The patients were randomly divided into three groups (each group included 60 patients) and received medial cemented Oxford phase 3 MB UKA, medial cemented Link FB UKA, or cemented DePuy Sigma PFC TKA, respectively. A similar perioperative management and fast-track surgery program was carried out for all patients. The knee scores at 3-year follow-up after operation and clinical efficacies of these three groups of patients were recorded, investigated, and compared. RESULTS: Primarily, compared to the TKA group, the UKA groups (MB UKA and FB UKA) had shorter operative time (median 63.2 < 67.1 min), less bleeding (8.6 < 30.0 mL), earlier resumption of walking without crutches (3.0 < 8.0 days) and walking up and down the stairs (5.0 < 10.0 days) (P < 0.001), higher FJS scores (78.0 > 74.5) (P = 0.007), better results in all knee scores (except VAS and KSS function scores) (P < 0.05), and a larger maximum flexion angle of the knee at the 3-year follow-up (123.0° > 96.0°) (P = 0.001). Secondarily, compared to the TKA group, the MB UKA group showed better results in the Western Ontario and McMaster Universities index (WOMAC) stiffness (83.6 > 79.6), WOMAC total (86.3 > 83.2), Oxford knee score (OKS) (20.0 < 23.0), Forgotten Joint Score (FJS) (78.5 > 74.5), and a larger maximum flexion angle of the knee (123.0 > 96.0) (P < 0.05). Moreover, the FB UKA group showed higher Hospital for Special Surgery Knee Score (HSS) (91.0 > 88.5), WOMAC stiffness (84.3 > 79.6), WOMAC function (85.2 > 81.7), WOMAC total scores (87.6 > 83.2), and a larger maximum flexion angle of the knee (119.0° > 96.0°) than the TKA group (P < 0.05). Overall, there was no significant difference in all knee scores and maximum flexion angles of the knee for the MB UKA and FB UKA groups (P > 0.05). There was one case with original bearing dislocation in MB UKA group. One patient with displacement of the femoral component caused by a fall injury, and another patient, who lost his life in a car accident, were involved in the FB UKA group. There was an infection case and an intermuscular vein thrombosis case in TKA group. CONCLUSION: UKA showed more advantages than TKA; however, there was no significant difference between the MB UKA and FB UKA groups for treatment of non-lateral compartmental knee OA.

Laxity measurement of internal knee rotation after primary anterior cruciate ligament rupture versus rerupture.

PURPOSE: The aim of the current study was to objectify the rotational laxity after primary anterior cruciate ligament (ACL) rupture and rerupture after ACL reconstruction by instrumented measurement. It was hypothesized that knees with recurrent instability feature a higher internal rotation laxity as compared to knees with a primary rupture of the native ACL. STUDY DESIGN: Cross-sectional study, Level of evidence III. METHODS: In a clinical cross-sectional study successive patients with primary ACL rupture and rerupture after ACL reconstruction were evaluated clinically and by instrumented measurement of the rotational and antero-posterior laxity with a validated instrument and the KT1000®, respectively. Clinical examination comprised IKDC 2000 forms, Lysholm Score, and Tegner Activity Scale. Power calculation and statistical analysis were performed (p value < 0.05). RESULTS: 24 patients with primary ACL rupture and 23 patients with ACL rerupture were included. There was no significant side-to-side difference in anterior translation. A side-to side difference of internal rotational laxity ≥ 10° was found significantly more frequent in reruptures (53.6%) compared to primary ruptures (19.4%; p < 0.001). A highly significant relationship between the extent of the pivot-shift phenomenon and side-to-side difference of internal rotation laxity could be demonstrated (p < 0.001). IKDC 2000 subjective revealed significantly better scores in patients with primary ACL tear compared to patients with ACL rerupture (56.4 ± 7.8 vs. 50.8 ± 6.2; p = 0.01). Patients with primary ACL tears scored significantly better on the Tegner Activity Scale (p = 0.02). No significant differences were seen in the Lysholm Score (p = 0.78). CONCLUSION: Patients with ACL rerupture feature significantly higher internal rotation laxity of the knee compared to primary ACL rupture. The extend of rotational laxity can be quantified by instrumented measurements. This can be valuable data for the indication of an anterolateral ligament reconstruction in ACL revision surgery.

Radiological Outcome Measures Indicate Advantages of Precontoured Locking Compression Plates in Elderly Patients With Split-Depression Fractures to the Lateral Tibial Plateau (AO41B3).

BACKGROUND: Split-depression fractures to the lateral tibial plateau (AO41B3) often feature severe joint surface destructions. Precontoured locking compression plates (LCPs) are designed for optimum support of the reduced joint surface and have especially been emphasized in reduced bone quality. A lack of evidence still inhibits their broad utilization in elderly patients. Thus, aim of the present study was to investigate the implant-specific radiological outcomes of AO41B3-fractures in young versus elderly patients. METHODS: The hospital's database was screened for isolated AO41B3-factures, open reduction and internal fixation (ORIF), and radiological follow-up ≥12 months. CT-scans, radiographs, and patients' records were analyzed. Patients were attributed as young (18-49) or elderly (≥50 years). Additional subgrouping was carried out into precontoured LCP and conventional implants. The Rasmussen Radiological Score (RRS) after 12 months was set as primary outcome parameter. The RRS postoperatively and the medial proximal tibial angle (MPTA) postoperatively and after 12 months were secondary outcome parameters. RESULTS: Fifty nine consecutive patients were included (26 young, 38.2 ± 7.8 years; 33 elderly, 61.3 ± 9.4 years). There were no significant differences regarding mean size and depression depth of the lateral joint surface fragments. Prior to implant-specific subgrouping, the radiological outcome measures revealed no significant differences between young (RRS = 7.7 ± 1.7; MPTA = 90.3 ± 2.3°) and elderly (RRS = 7.2 ± 1.7; MPTA = 90.5 ± 3.3°). After implant-specific subgrouping, the radiological outcome revealed significantly impaired results in young patients with conventional implants (RRS(C) = 6.9 ± 1.6, RRS(LCP) = 8.5 ± 1.5, P = .015; MPTA(C) = 91.5 ± 1.9°, MPTA(LCP) = 89.1 ± 2.1°, P = .01). The effect was even more pronounced in elderly patients, with highly significant deterioration of the radiological outcome measures for conventional implants compared to precontoured LCP (RRS(C) = 5.7 ± 1.6, RRS(LCP) = 8.2 ± .8, P < .001; MPTA(C) = 92.6 ± 4.2°, MPTA(LCP) = 89.2 ± 1.4°, P = .002). CONCLUSION: Utilizing precontoured LCP in the treatment of AO41B3-fractures is associated with improved radiological outcomes. This effect is significant in young but even more pronounced in elderly patients. Consequently, precontoured LCP should closely be considered in any AO41B3-fracture, but especially in elderly patients.

A New Three-Dimensional Classification of Proximal Tibiofibular Fractures: A Multicenter Study.

OBJECTIVES: To propose an updated definition of proximal tibia and fibula fracture (PTFF) and establish a three-dimensional (3D) structure-based classification of PTFF. METHODS: In total, 1358 adult patients (837 males and 521 females; 43.61 ± 15.13 years， 1364 affected knees) who were diagnosed with PTFF at the departments of orthopaedic surgery of four hospitals from January 2010 to December 2019 were enrolled. The new classification of PTFF, termed Wu classification, included three parts: classification of columns in the horizontal plane, regions in the frontal plane, and segments in the sagittal plane. All PTFFs were classified according to Schatzker, Luo, and Wu classification systems. Additionally, the incidence and characteristics of PTFFs were analyzed. RESULTS: The major internal structural fractures of PTFF were tibial plateau fracture (TPF) only (725, 53.15%), TPF and proximal fibular fracture (274, 20.09%), and isolated avulsion fracture of the posterior cruciate ligament (PCL) (189, 13.86%). Approximately a quarter of PTFF cases could not be classified using Schatzker or Luo classifications, but all PTFF cases could be classified using Wu classification. The most frequent PTFFs included all four columns in region IV, segment 2 (235, 17.23%); the posterolateral and posteromedial columns in region II, segment 2 (191, 14.00%); and the lateral and posterolateral columns in region IV, segment 2 (136, 9.97%). Isolated avulsion fracture of the anterior cruciate ligament (ACL) was categorized as three injury types, most of which involved the lateral and medial columns in region II, segment 1 (40/63, 64%). More than 97% of cases of isolated fractures of the PCL involved the posterolateral and posteromedial columns in region II, segment 2. The most frequent combined avulsion fracture of the ACL and PCL included all four columns in region II, segment 2 (18/24, 75%). All of the isolated avulsion fractures of the ACL were located in segment 1, and all those of the PCL in segment 2. The most common type of isolated proximal fibular fracture involved the posterolateral column in region III, segment 2 (23/26, 88%). The most frequent combined TPF and proximal fibular fracture involved all four columns in region IV, segment 2 (107/274, 39.05%). CONCLUSIONS: All cases of PTFF could be classified by the new 3D Wu classification which should be beneficial for clinical diagnosis, guidance of treatment, statistical analysis, academic communication, and prognosis, and the most frequent PTFF involved all four columns in region IV, segment 2.

Anteversion Angle Measurement in Suspected Torsional Malalignment of the Femur in 3-Dimensional EOS vs Computed Tomography-A Validation Study.

BACKGROUND: Computed tomography (CT) scan is the standard for assessment of femoral torsion. This observational study was conducted to evaluate the comparability of the EOS radiation dose scanning system (EOS imaging, Paris, France) and the CT scan in patients with suspected torsional malalignment of the femur. METHODS: Patients with suspected torsional malalignment of the femur were included in a study for surgical planning. The primary endpoint was to compare the 3-dimensional radiological (EOS) imaging system with the CT scan to determine femoral anteversion (AV) angle. Three independent raters performed measurements. Comparability of CT scan and EOS values was assessed by Pearson correlation, t test, interobserver reliability, and intraobserver reliability (Cronbach alpha). RESULTS: About 34 femora were examined. Interobserver reliability/intraobserver reliability was 0.911 of 0.955 for EOS and 0.934 of 0.934 for CT scan. EOS system revealed an AV angle of 12.2° ± 10.0° (-15.0° to 32.0°). CT examinations showed an AV angle of 12.6° ± 9.2° (-3.2° to 35.6°). About 11 hips featured physiological AV, 14 hips showed decreased AV (<10°) or retroversion (<0°), and 9 hips showed increased AV (>20°). Overall, a strong Pearson correlation of τ = 0.855 and a highly significant correlation in the t test for both methods was seen. In patients with decreased AV, retroversion, or increased AV, Pearson correlation only resulted in a moderate/low correlation of τ = 0.495 and τ = 0.292. The t test showed no significant correlation at malrotation. CONCLUSION: In torsional malalignment, EOS does not have correlation with CT measurements. In contrast to CT scan, EOS allows femoral torsion measurement independent of legs' positioning.

Histomorphological Alterations of Human Anterior Cruciate Ligament Grafts During Mid-Term and Long-Term Remodeling.

OBJECTIVE: The aim of the present paper is to analyze mid-term and long-term alterations of human anterior cruciate ligament (ACL) grafts during the remodeling process with special regards to cellularity, α-smooth muscle protein (αSMP) expression, and crimp length in comparison to the native ACL. METHODS: A total of 34 patients were included (23 male and 11 female). Biopsies of 13 semitendinosus tendon and 14 patellar tendon autografts were obtained during surgical revision secondary to an ACL reconstruction. According to the interval between the index procedure and sample collection, the patients were divided into four groups: 4-12 months, 13-60 months, 61-108 months, and >108 months. Seven samples of native ruptured ACL tissue obtained during surgical intervention served as control. All biopsies were taken from the intraligamentous part of the ACL or the graft. Histomorphological and immunohistochemical analyses were conducted after samples were stained using hematoxylin-eosin, Giemsa, and αSMP enzyme-labeled antibodies. The total cell density, the numbers of fibroblasts and fibrocytes, the fibroblast/fibrocyte ratio, the number of αSMP+ cell nuclei, and the percentage of αSMP+ cells per fibroblast as well as the crimp lengths were determined using light microscopy. RESULTS: In the early phase of remodeling, the grafts featured extensively high total cell counts (1021.2 ± 327.8, P = 0.001), with high numbers of fibroblasts (841.4 ± 245.2, P = 0.002), fibrocytes (174.5 ± 113.0, P = 0.04), and αSMP+ cells (78.3 ± 95.0, P = 0.02) compared to controls (390.1 ± 141.7, 304.5 ± 160.8, 65.6 ± 31.4 and 2.3 ± 2.6, respectively). Thereafter, the numbers of all cell entities decreased. After more than 108 months, the percentage of αSMP+ cells per fibroblast reached physiological values (ratio 1.3 ± 1.0, P = 0.41; control 0.8 ± 0.8), while the total cell count (834.3 ± 183.7, P = 0.001) as well as the numbers of fibroblasts (663.5 ± 192.6, P = 0.006) and fibrocytes (134.1 ± 73.0, P = 0.049) remained significantly high. The fibroblast/fibrocyte ratio showed no significant alterations over the course of time compared to the controls. The collagen crimp lengths were elongated by tendency in the early phase (28.8 ± 12.9 mm, P = 0.15; control 20.7 ± 2.2 mm) and significantly shortened over time, with the lowest values in the long term (14.8 ± 2.0 mm, P = 0.001). The comparison of biopsies from semitendinosus tendon and patellar tendon autografts revealed no significant differences for any of the histomorphological parameters investigated. CONCLUSION: This study reveals distinctive mid-term and long-term immunomorphological alterations during human ACL graft remodeling. These data clearly indicate that the remodeling is a process that continues for 9 years or more. Furthermore, it seems to be a process of adaptation rather than full restoration. Even in the long run, several biological properties of the native ACL are not completely reestablished.

Editorial Commentary: Revision of Failed Double-Bundle Anterior Cruciate Ligament Reconstruction.

Double-bundle (DB) reconstruction of the anterior cruciate ligament was favored for several years. However, recent studies increasingly show that this technique does not provide a clear advantage over the less-invasive single-bundle technique. Unfortunately, the graft fails relatively often after ACL reconstruction. Postoperative communication of the bone tunnels through bone tunnel widening is possible. Since 2 drill channels are created in the DB technique, femoral as well as tibial, it is assumed that this technique may cause problems during revision. So, in part, revision may require a 2-step procedure with bone graft filling of the tunnels as the first step. It is important that surgeons with experience using DB publish their revision strategies and experiences.

Expression of xylosyltransferases I and II and their role in the pathogenesis of arthrofibrosis.

BACKGROUND: Arthrofibrosis is a painful and restraining complication that occurs after about 10% of total knee arthroplasty and cruciate ligament surgery. The pathogenesis of arthrofibrosis has not yet been fully understood. Stress signals stimulate immune cells, and fibroblast differentiates into myofibroblast, which produce a large amount of collagen. Xylosyltransferases also appear to be involved in these pathways. They catalyze proteoglycan biosynthesis, which is involved in tissue remodeling and myofibroblast differentiation. The aim of this study was to investigate the relationship between the disease arthrofibrosis and the expression of the two isoforms of xylosyltransferases I and II. METHODS: Tissue samples from 14 patients with arthrofibrosis were compared with tissue samples from seven healthy controls. The xylosyltransferases were detected by immunohistochemistry. The tissues were divided into four different areas of interest: vessels, synovialis, cell-poor and cell-rich fibrosis, or cell-poor and cell-rich areas in the control group. A quantification of the results was performed by modification of the immunoreactive score according to Remmele and Stegner. RESULTS: Xylosyltransferase I was expressed in the various tissue types at varying rates. Xylosyltransferase I expression was considerably and significantly stronger than that of xylosyltransferase II. The following sequences of xylosyltransferase I and xylosyltransferase II expression were determined as follows: vessels >> cell-rich fibrosis > cell-poor fibrosis > synovialis. A positive correlation between the number of positive fibroblasts and the immunoreactive scoring system (IRS) was documented. CONCLUSIONS: The significant positive correlation of xylosyltransferase -I expression with increasing number of fibroblasts demonstrates a high myofibroblast differentiation rate, which implies a gradual event as the pathogenesis of arthrofibrosis.

Inversely 3D-Printed ß-TCP Scaffolds for Bone Replacement.

The aim of this study was to predefine the pore structure of ß-tricalcium phosphate (ß-TCP) scaffolds with different macro pore sizes (500, 750, and 1000 µm), to characterize ß-TCP scaffolds, and to investigate the growth behavior of cells within these scaffolds. The lead structures for directional bone growth (sacrificial structures) were produced from polylactide (PLA) using the fused deposition modeling techniques. The molds were then filled with ß-TCP slurry and sintered at 1250 °C, whereby the lead structures (voids) were burnt out. The scaffolds were mechanically characterized (native and after incubation in simulated body fluid (SBF) for 28 d). In addition, biocompatibility was investigated by live/dead, cell proliferation and lactate dehydrogenase assays. The scaffolds with a strand spacing of 500 µm showed the highest compressive strength, both untreated (3.4 ± 0.2 MPa) and treated with simulated body fluid (2.8 ± 0.2 MPa). The simulated body fluid reduced the stability of the samples to 82% (500), 62% (750) and 56% (1000). The strand spacing and the powder properties of the samples were decisive factors for stability. The fact that ß-TCP is a biocompatible material is confirmed by the experiments. No lactate dehydrogenase activity of the cells was measured, which means that no cytotoxicity of the material could be detected. In addition, the proliferation rate of all three sizes increased steadily over the test days until saturation. The cells were largely adhered to or within the scaffolds and did not migrate through the scaffolds to the bottom of the cell culture plate. The cells showed increased growth, not only on the outer surface (e.g., 500: 36 ± 33 vital cells/mm² after three days, 180 ± 33 cells/mm² after seven days, and 308 ± 69 cells/mm² after 10 days), but also on the inner surface of the samples (e.g., 750: 49 ± 17 vital cells/mm² after three days, 200 ± 84 cells/mm² after seven days, and 218 ± 99 living cells/mm² after 10 days). This means that the inverse 3D printing method is very suitable for the presetting of the pore structure and for the ingrowth of the cells. The experiments on which this work is based have shown that the fused deposition modeling process with subsequent slip casting and sintering is well suited for the production of scaffolds for bone replacement.

Viscoelasticity and histology of the human cartilage in healthy and degenerated conditions of the knee.

BACKGROUND: There are many studies on osteoarthritis, but only a few studies deal with human arthrosis, comparing the mechanical properties of healthy and diseased samples. In most of these studies, only isolated areas of the tibia are examined. There is currently only one study investigating the complete mapping of cartilage tissue but not the difference between instantaneous modulus (IM) in healthy and diseased samples. The aim of this study is to investigate the relationship between the biomechanical and histological changes of articular cartilage in the pathogenesis of osteoarthritis. METHODS: The study compared 25 tibiae with medial gonarthrosis and 13 healthy controls. The IM was determined by automated indentation mapping using a Mach-1 V500css testing machine. A grid was projected over the sample and stored so that all measurements could be taken at the same positions (100 ± 29 positions across the tibiae). This grid was then used to perform the thickness measurement using the needle method. Samples were then taken for histological examinations using a hollow milling machine. Then Giemsa and Safranin O staining were performed. In order to determine the degree of arthrosis according to histological criteria, the assessment was made with regard to Osteoarthritis Research Society International (OARSI) and AHO scores. RESULTS: A significant difference (p < 0.05) could be observed in the measured IM between the controls with 3.43 ± 0.36 MPa and the samples with 2.09 ± 0.18 MPa. In addition, there was a significant difference in IM in terms of meniscus-covered and meniscus-uncovered areas. The difference in cartilage thickness between 2.25 ± 0.11 mm controls and 2.0 ± 0.07 mm samples was highly significant with p < 0.001. With regard to the OARSI and AHO scores, the samples differed significantly from the controls. The OARSI and AHO scores showed a significant difference between meniscus-covered and meniscus-uncovered areas. CONCLUSIONS: The controls showed significantly better viscoelastic behavior than the arthrotic samples in the measured IM. The measured biomechanical values showed a direct correlation between histological changes and altered biomechanics in gonarthrosis.

The value of elbow arthroscopy in diagnosing and treatment of radial head fractures.

BACKGROUND: Surgical treatment of radial head fractures is increasingly performed arthroscopically. These fractures often feature concomitant injuries to the elbow joint, which may be under-diagnosed in the radiological examinations. Little is known about the diagnostic value of arthroscopy, the treatment options that arise from arthroscopically assisted fracture fixation and clinical results. We hypothesized that arthroscopy can detect additional concomitant injuries and simultaneously expands the therapeutic options. Therefore aim of this study was to compare arthroscopic and radiologic findings, to assess the distinct arthroscopic procedures and to follow up on the clinical outcomes. METHODS: Twenty patients with radial head fractures were retrospectively included in two study centers. All patients underwent elbow arthroscopy due to at least one of the following suspected concomitant injuries: osteochondral lesions of the humeral capitellum, injuries of the collateral ligaments or loose joint bodies. Preoperative radiological findings were compared to arthroscopic findings. Afterwards, arthroscopic treatment options and clinical outcomes were assessed. RESULTS: Arthroscopic findings led to revision of the classified fracture type in 70% (p = 0.001) when compared to preoperative conventional radiographs (CR) and in 9% (p = 0.598) when compared to computed tomography (CT) or magnetic resonance imaging (MRI). Diagnosis of loose bodies was missed in 60% (p < 0.001) of the CR and in 18% (p = 0.269) of the CT/MRI scans. Osteochondral lesions were not identified in 94% (p < 0.001) of the CR and in 27% (p = 0.17) of the CT/MRI scans. Percutaneous screw fixation was performed in 65% and partial radial head resection in 10%. Arthroscopy revealed elbow instability in 35%, leading to lateral collateral ligament reconstruction. After a mean follow up of 41.4 ± 3.4 months functional outcome was excellent in all cases (DASH-Score 0.6 ± 0.8; MEPI-Score 98.5 ± 2.4; OES-Score 47.3 ± 1.1). CONCLUSIONS: Elbow arthroscopy has a significant diagnostic value in radial head fractures when compared to standard radiological imaging. Although statistically not significant, arthroscopy also revealed concomitant injuries in patients that presented with an uneventful MRI/CT. Furthermore, all intraarticular findings could be treated arthroscopically allowing for excellent functional outcomes. TRIAL REGISTRATION: Institutional Review Board University of Munich (LMU), Trial Number 507-14.

Alendronate Release from UHMWPE-Based Biomaterials in Relation to Particle Size of the GUR Powder for Manufacturing.

Ultra-high molecular weight polyethylene (UHMWPE) is widely used in endoprosthetics and has been the subject of countless studies. This project investigates the dependence of alendronate (AL) release on the molecular weight of the UHMWPE used (GUR1020 and GUR1050). A 0.5 wt% AL was added to the UHMWPE during the production of the moldings. In addition to the 14-day release tests, biocompatibility tests such as live dead assay, cell proliferation assay (WST) and Lactate dehydrogenase test (LDH) with MG-63 cells as well as a tensile test according to DIN EN ISO 527 were carried out. The released AL concentration was determined by HPLC. A continuous release of the AL was observed over the entire period of 2 weeks. In addition, a correlation between molar mass and AL release was demonstrated. The GUR1020 showed a release four times higher than the GUR1050. Both materials have no negative influence on the proliferation of MG-63 cells. This was also confirmed in the live/dead assay by the increase in cell count. No cytotoxicity was detected in the LDH test. The addition of 0.5 wt% AL increased the elongation at break for GUR1020 by 23% and for GUR1050 by 49%. It was demonstrated that the choice of UHMWPE has an influence on the release of AL. The particle size in particular has a strong influence on the release behavior.

Editorial Commentary: No Difference in Knee Osteoarthritis After Single-Bundle Versus Double-Bundle Anterior Cruciate Ligament Reconstruction.

Systematic reviews now play a key role in evidence-based medicine, summarizing empirical findings from evaluated studies on a specific problem and examining the variability of those. These reviews help scientists integrate and evaluate relevant information in their research and support practitioners in decision-making processes. Since the early years of the current century, there has been a debate as to whether double-bundle or single-bundle reconstruction of the anterior cruciate ligament will better protect the knee. An essential aspect in the general indication of ligament reconstruction of the knee joint is the aim to prevent or at least to slow down the development process of osteoarthritis. At present, most clinical measures show no difference in outcome between single-bundle and double-bundle anterior cruciate ligament reconstruction. Systematic review of the literature investigating development of knee osteoarthritis after single-bundle and double-bundle anterior cruciate ligament reconstruction also shows no difference in outcome for this very important measure.

Immunohistochemical examination in arthrofibrosis of the knee joint.

INTRODUCTION: Arthrofibrosis (AF) is the result of increased cell proliferation and synthesis of matrix proteins (collagen I, III, and VI). Especially after invasive knee surgery, e.g., ligament reconstruction or knee replacement, abnormal fibroblast proliferation with pathological periarticular fibrosis can be observed leading to severely limited joint motion. The pathogenesis of AF is currently not fully understood. The present work aims to determine pathogenic factors. MATERIALS AND METHODS: A descriptive, histological and immunohistochemical comparative study was performed on tissue samples of 14 consecutive patients undergoing arthrolysis for joint stiffness due to AF. Seven human autopsy specimens served as control. Samples were stained for expression of relevant markers such as CD68, α-smooth muscle actin (ASMA), beta-catenin, BMP-2 and examined for the histological grade of AF (cell-rich versus cell-poor) and compared to a control. Furthermore, a microscopic evaluation of the samples for cell differentiation and number was performed. RESULTS: Tissue sections of cell-rich fibrosis showed a significantly higher expression of CD68 compared to the control with less than 10% of CD68 positive cells (p = 0.002). In cell-poor fibrosis no statistically significant difference was obvious (p = 0.228). Expression of ASMA in synovia, vessels, cell-rich and cell-poor fibrosis showed median values of 2.00 in the AF group and 1.75 in the control. Both groups differed significantly (p = 0.003). AF tissue showed a significantly difference in expression of ß-catenin (p < 0.001) compared to the control. The overall difference between AF and control group in expression of BMP-2 was also statistically significant (p = 0.002). CONCLUSIONS: Expression of CD68, ASMA, beta-catenin and BMP-2 is significantly increased in AF tissue samples. Based on presented findings, histological evaluation and immunohistochemical assessment of CD68, ASMA, ß-catenin and BMP-2 expression may proof useful to diagnose AF and to analyze AF activity.