Can the Sterilization Protocol Be Improved to Enhance the Healing of Allograft Tendons? An In Vivo Study in Rabbit Tendons.

BACKGROUND: Peracetic acid and irradiation are common sterilization methods for allograft tendons; however, under some conditions, both methods adversely affect the fiber arrangement and ultimate load of the tendon. An in vitro study showed that low-dose peracetic acid combined with irradiation may be less detrimental to allograft tendon structure and properties, possibly because the breakdown of peracetic acid can lead to an enlargement of the interstitial spaces and an increase in porosity. QUESTIONS/PURPOSES: Using a rabbit Achilles tendon model, we asked: What is the effect of peracetic acid-ethanol combined irradiation on (1) the histopathology and fiber diameter of the allograft tendon, (2) tensile creep and load-to-failure biomechanical properties of allograft tendons, and (3) healing of the treated tendon in vivo compared with fresh-frozen allograft and peracetic acid-ethanol sterilization at 4 and 8 weeks? METHODS: The Achilles tendons used in this study were sourced from euthanized 10-week-old male New Zealand White rabbits previously used for ophthalmic experiments. All allografts were divided into three groups: fresh-frozen group (control group, n = 20), peracetic acid-ethanol sterilization group (n =20), and peracetic acid-ethanol combined irradiation group (n = 20). The sterilization protocols were performed per a predetermined plan. In the peracetic acid-ethanol sterilization group, the tendon tissues were covered with the peracetic acid-ethanol sterilization solution (1% peracetic acid for 30 minutes). In the peracetic acid-ethanol combined irradiation group, the tendon tissues were covered with the peracetic acid-ethanol sterilization solution (0.2% peracetic acid for 30 minutes) and were subjected to 15 kGy gamma irradiation. Thirty 10-week-old male New Zealand White rabbits received bilateral Achilles tendon allografts surgically. Tendon samples from each group were harvested at 4 weeks (n = 30) and 8 weeks (n = 30) postoperatively. For each timepoint, eight tissues were used for histologic staining and electron microscopy, 15 tissues were used for biomechanical testing, and seven tissues were used for hydroxyproline assay and quantitative polymerase chain reaction. Histopathology was determined qualitatively by hematoxylin and eosin and Masson staining, while fiber diameter was measured quantitatively by transmission electron microscopy. Biomechanical properties were measured using cyclic loading tests and load-to-failure tests. The healing outcome was quantitatively judged through healing-related genes and proteins. RESULTS: At 4 weeks and 8 weeks postoperatively, the peracetic acid-ethanol combined irradiation group visually demonstrated the best continuity and minimal peripheral adhesions. Histologic staining showed that tendon fibers in the peracetic acid-ethanol combined irradiation group maintained consistent alignment without notable disruptions or discontinuities, and there was a qualitatively observed increase in the number of infiltrating cells compared with the control group at the 4-week timepoint (444 ± 49 /mm 2 versus 256 ± 43 /mm 2 , mean difference 188 /mm 2 [95% confidence interval 96 to 281]; p < 0.001). At 8 weeks postoperatively, the tendon fiber diameter in the peracetic acid-ethanol combined irradiation groups was similar to that of the control group (0.23 ± 0.04 µm versus 0.21 ± 0.03 µm, mean difference 0.02 µm [95% CI -0.04 to 0.08]; p = 0.56). At 8 weeks postoperatively, the peracetic acid-ethanol combined irradiation group exhibited better properties in terms of both ultimate load (129 ± 15 N versus 89 ± 20 N, mean difference 40 N [95% CI 7 to 73]; p = 0.02) and energy absorption density (17 ± 6 kJ/m 2 versus 8 ± 4 kJ/m 2 , mean difference 8 kJ/m 2 [95% CI 0.7 to 16]; p = 0.004) compared with the control group. Gene expression analysis revealed higher expression levels of COL1A1 (2.1 ± 0.8 versus 1.0 ± 0, mean difference 1.1 [95% CI 0.1 to 2.1]; p = 0.003) and MMP13 (2.0 ± 0.8 versus 1.0 ± 0, mean difference 1.0 [95% CI 0.4 to 1.6]; p = 0.03) in the peracetic acid-ethanol combined irradiation group than in the control group. There was a higher amount of collagen Type I in tendons treated with peracetic acid-ethanol combined irradiation than in the control group (0.36 ± 0.03 versus 0.31 ± 0.04, mean difference 0.05 [95% CI 0.01 to 0.09]; p = 0.02). CONCLUSION: Treatment with peracetic acid-ethanol combined irradiation did not have any discernible adverse effect on the histology, fiber diameter, enzymatic resistance, collagen content, or biomechanical strength of the allograft tendons compared with the control group. Peracetic acid-ethanol combined irradiation treatment had a positive impact on remodeling of the extracellular matrix and realignment of collagen fibers. CLINICAL RELEVANCE: This sterilization method could be helpful to expand the scope and frequency with which allogeneic materials are applied. The long-term healing effect and strength of allograft tendons must be tested before clinical use, and it is necessary to conduct comparative studies on autografts and synthetic materials that are currently widely used clinically.

U-shaped kirschner wire transfixation: effective treatment for Skier's thumb.

BACKGROUND: Skier's thumb is a type of injury to the ulnar collateral ligament of the metacarpophalangeal joint of the thumb, which can result in bone fragmentation and joint instability. OBJECTIVE: The objective of this study was to compare the traditional Kirschner wire fixation method with the U-shaped Kirschner wire method for treating small bone fragments with displacement, rotation, or instability in skier's fractures. METHOD: A retrospective study was conducted on 30 patients with skier's thumb who were treated at Tianjin Hospital from January 2019 to December 2021. Patients were divided into two groups: Group A received traditional Kirschner wire fixation, while Group B received U-shaped Kirschner wire fixation. Functional assessments and complications during the perioperative period were evaluated. RESULTS: Both surgical methods significantly reduced postoperative pain and increased joint range of motion. Group B had a lower incidence of pain during follow-up and showed significant functional improvement in Tip-pinch and Grip tests compared to Group A. U-shaped Kirschner wire fixation significantly reduced complications during the perioperative period. CONCLUSION: The U-shaped Kirschner wire internal fixation is a safe and effective treatment for the thumb proximal phalanx base ulnar side avulsion fracture.

The trend of allogeneic tendon decellularization: literature review.

Tendon injuries repair is a significant burden for orthopaedic surgeons. Finding a proper graft material to repair tendon is one of the main challenges in orthopaedics, for which the requirement of substitute for tendon repair would be different for each clinical application. Among biological scaffolds, the use of decellularized tendon increasingly represents an interesting approach to treat tendon injuries and several articles have investigated the approaches of tendon decellularization. To understand the outcomes of the the approaches of tendon decellularization on effect of tendon transplantation, a literature review was performed. This review was conducted by searching in Pubmed and Embase and 64 studies were included in this study. The findings revealed that the common approaches to decellularize tendon include chemical, physical, and enzymatic decellularization methods or their combination. With the development of tissue engineering, researchers also put forward new theories such as automatic acellular machine, 3D printing technology to manufacture acellular scaffold.

The Correlation of Dynamic Magnetic Resonance Imaging Evaluation With Histological, Biochemical, and Biomechanical Properties in Healing Progress After Achilles Tendon Injury: A Review.

Achilles tendon injury is a common sports injury, and an in-depth understanding of its healing process is essential for improving rehabilitation strategies. As a non-invasive imaging technology with excellent anatomical and functional information extraction abilities, magnetic resonance imaging (MRI) has been widely used in the evaluation and monitoring of Achilles tendon injury. MRI scans at different stages of Achilles tendon healing can provide information about the structure of the Achilles tendon tissue, blood supply, composition, and metabolism. The change pattern on dynamic MRI evaluation is closely related to the specific stage of Achilles tendon healing and tissue characteristics. For example, the signal strength of dynamic enhanced MRI sequences can reflect blood supply to the Achilles tendon, whereas some quantitative MRI techniques can provide information on the recovery of water and collagen contents in the Achilles tendon. This article discusses the pathophysiological changes after Achilles tendon injury and summarizes the clinical and research status of the MRI techniques used for monitoring Achilles tendon healing. The feasibility of various MRI techniques for monitoring Achilles tendon healing and their correlation with histology, biochemistry, and biomechanics are reviewed, along with the challenges, limitations, and potential opportunities for their application. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 2.

Comparison of intraoperative blood loss and perioperative complications between preoperative embolization and nonembolization combined with spinal tumor surgeries: a systematic review and meta-analysis.

PURPOSE: The present study aimed to comparatively evaluate intraoperative blood loss (IBL) and perioperative complications between preoperative embolization (PE) and nonembolization (NE) combined with spinal tumor surgeries as well as to determine the subgroup of spinal tumor surgeries suitable for PE. METHODS: A systematic search in PubMed and EMBASE and an additional search by reference lists of the retrieved studies were undertaken by two reviewers. The mean IBL and perioperative complication rate were employed as the effect size in the general quantitative synthesis through direct calculation. Meta-analysis was performed using standardized mean difference (SMD) and weighted mean difference (WMD) of IBL and the odds ratio (OR) of complications. Heterogeneity was assessed using the I2 statistic. RESULTS: The reviewers selected 17 published studies for the general quantitative synthesis and meta-analyses. The mean IBL of spinal tumor surgeries was 1786.3 mL in the NE group and 1716.4 mL in the PE group. The mean IBL between the two groups was similar. The pooled WMD and SMD of IBL in spinal tumor surgeries was 324.15 mL (95% CI 89.50-1640.9, p = 0.007) and 0.398 (95% CI 0.114-0.682, p = 0.006), respectively. The reduction of the PE group compared with the NE group for the rates of major complications and major hemorrhagic complications were 7.80% and 5.71%, respectively. The risk of PE-related complications in the PE group was only 1.53% more than in the PE group. The pooled OR of major complications in spinal tumor surgeries was 1.426 (95% CI 0.760-2.674; p = 0.269). CONCLUSIONS: PE may be suitable for spinal tumor surgeries and some subgroups. From the perspective of complications, PE may also be a feasible option for spinal tumor surgeries.

Quantile regression-based prediction of intraoperative blood loss in patients with spinal metastases: model development and validation.

PURPOSE: To develop and evaluate a quantile regression-based blood loss prediction model for open surgery of spinal metastases. METHODS: This was a multicenter retrospective cohort study. Over a 11-year period, patients underwent open surgery for spinal metastases at 6 different institutions were reviewed. The outcome measure is intraoperative blood loss (in mL). The effects of baseline, histology of primary tumor and surgical procedure on blood loss were evaluated by univariate and multivariate analysis to determine the predictors. Multivariate ordinary least squares (OLS) regression and 0.75 quantile regression were used to establish two prediction models. The performance of the two models was evaluated in the training set and the test set, respectively. RESULTS: 528 patients were included in this study. Mean age was 57.6 ± 11.2 years, with a range of 20-86 years. Mean blood loss was 1280.1 ± 1181.6 mL, with a range of 10 ~ 10,000 mL. Body mass index (BMI), tumor vascularization, surgical site, surgical extent, total en bloc spondylectomy and microwave ablation use were significant predictors of intraoperative blood loss. Hypervascular tumor, higher BMI, and broader surgical extent were related with massive blood loss. Microwave ablation is more beneficial in surgery with substantial blood loss. Compared to the OLS regression model, the 0.75 quantile regression model may decrease blood loss underestimate. CONCLUSION: In this study, we developed and evaluated a prediction model for blood loss in open surgery for spinal metastases based on 0.75 quantile regression, which may minimize blood loss underestimate.

Relative influence on cell behaviors of osteoblasts seeded onto demineralized bone matrix with diverse particle size.

Demineralized bone matrix (DBM) is a natural and collagen-based allogeneic bone graft material with good bioactivity and biocompatibility. However, there are conflicting reports on the efficiency of this product owning to the relevant factors, especially, the particle size of DBM. In the current study, osteoblasts were seeded onto DBM with diverse particle sizes of 0.6-1.0 mm, 2.2-2.6 mm, 3.8-4.2 mm and 5.4-5.8 mm, and then the cell adhesion, proliferation, differentiation and apoptosis were analyzed to evaluate the effects of particle sizes on bioactivity and biocompatibility of DBM. It could be identified that particle size had a significant influence on the surface roughness and the collagen structure of DBM. In-vitro cytological assays had confirmed that DBM with all particle sizes had good cytocompatibility, which was beneficial for cell survival. What's more, DBM with a smaller particle size had a better biological activity and could promote cell proliferation and differentiation. We hope that researchers could choose to apply DBM with particle size of 0.6-1.0 mm for further intensive study, from which researchers will acquire more comparable and reliable conclusions for different study purposes.

Effects of demineralization mode and particle size of allogeneic bone powder on its physical and chemical properties.

At present, the commonly used allogeneic bone powder in the clinic can be divided into nondemineralized bone matrix and demineralized bone matrix (DBM). Commonly used demineralizers include acids and ethylene diamine tetraacetic acid (EDTA). There may be some diversities between them. Also, the size of the bone particle can affects its cell compatibility and osteogenic ability. We produced different particle sizes i.e., < 75, 75-100, 100-315, 315-450, 450-650, and 650-1000 µm, and treated in three ways (nondemineralized, demineralized by EDTA, and demineralized by HCl). Scanning electron microscopy showed that the surface of the samples in each group was relatively smooth without obvious differences. The results of specific surface area and porosity analysis showed that they were significantly higher in demineralized bone powder than in nondemineralized bone powder, however, there was no significant difference between the two decalcification methods. The content of hydroxyproline in nondemineralized bone powder and EDTA-demineralized bone powder had no statistical difference, while HCl-demineralization had statistical significance compared with the former two, and the content increased with the decrease of particle size. The protein and BMP-2 extracted from HCl demineralized bone powder were significantly higher than that from nondemineralized bone powder and EDTA demineralized bone powder, and there were differences among different particle sizes. These results suggested the importance of demineralization mode and particle size of the allogenic bone powder and provided guidance for the choice of the most appropriate particle size and demineralization mode to be used in tissue bioengineering.

Repair of tendons treated with peracetic acid-ethanol and gamma irradiation by EDC combined with NHS: a morphological, biochemical and biomechanical study in vitro.

The purpose of this study was to investigate whether 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) combined with n-hydroxysuccinimide (NHS) can repair tendon damage caused by peracetic acid-ethanol and gamma irradiation sterilization. The semitendinosus tendons of 15 New Zealand white rabbits were selected as experimental materials, and the tendons were sterilized in a solution containing 1% (v/w) peracetic acid and 24% (v/w) ethanol. After 15 kGy gamma irradiation sterilization, the tendons were randomly divided into three groups (n = 10). The tendons were repaired with EDCs of 0, 2.5 and 5 mM combined with 5 mM NHS for 6 h, the tendons were temporarily stored at - 80 ± °C. The arrangement and spatial structure of collagen fibers were observed by light microscopy and scanning electron microscopy, the collagen type and collagen crimp period were observed under a polarizing microscope, and the collagen fibril diameter and its distribution were measured by transmission electron microscopy, from which the collagen fibril index and mass average diameter were calculated. The resistance of collagen to enzymolysis was detected by the free hydroxyproline test, and tensile fracture and cyclic loading tests of each group of tendons were carried out, from which the elastic modulus, maximum stress, maximum strain, strain energy density and cyclic creep strain were calculated. The obtained results showed that the gap between loose collagen fibers in the 0 mM control group was wider, the parallel arrangement of tendons in the 2.5 and 5 mM groups was more uniform and regular and the fiber space decreased, the crimp period in the 5 mM group was lower than that in the 0 mM group (P < 0.05), and the concentration of hydroxyproline in the 5 mM group (711.64 ± 77.95 µg/g) was better than that in the control group (1150.57 ± 158.75 µg/g). The elastic modulus of the 5 mM group (424.73 ± 150.96 MPa) was better than that of the 0 mM group (179.09 ± 37.14 MPa). Our results show that EDC combined with NHS can repair damaged tendons after peracetic acid-ethanol and gamma radiation treatment, and 5 mM EDC has better morphological performance, anti-enzymolysis ability and biomechanical properties than 2.5 mM EDC.

Comparison of demineralized bone matrix with different cycling crushing times in posterolateral fusion model of athymic rats.

Decalcified bone matrix (DBM) is a widely used alternative material for bone transplantation. In the DBM production process, an effective particle size and the highest utilization rate of raw materials can be achieved only through multiple high-speed circulating comminution. The rat posterolateral lumbar fusion model (PLF) is the most mature small animal model for the initial evaluation of the efficacy of graft materials for bone regeneration and spinal fusion. To evaluate the differences in the in vivo osteogenic effects of DBM pulverization through 1, 5, 9, and 14 high-speed cycles, sixty athymic rats were divided into six groups: single cycling crushing (CC1), 5 cycles of crushing (CC5), 9 cycles of crushing (CC9), 13 cycles of crushing (CC13), autogenous bone graft (ABG) and negative control (NC). Posterolateral lumbar fusion was performed. Six weeks after surgery, the bilateral lumbar fusion of athymic rats was evaluated through manual palpation, X-ray, micro-CT and histological sections. Rank data were tested by the rank-sum test, and nonparametric data were tested by the Kruskal‒Wallis H test. The manual palpation and X-ray results showed that the fusion rate did not significantly differ between the CC1, CC5, CC9, CC13 and ABG groups. However, cavities appeared in CC9 and CC13 on the micro-CT image. The bone mass (BV/TV) of CC1, CC5, CC9 and CC13 was better than that of the ABG group, while almost no osteogenesis was observed in the NC group. Histologically, there was no obvious difference between the four groups except that the CC9 group and CC13 group had more fibrous tissues in the new bone. In conclusion, DMB with different cycling crushing times has no obvious difference in fusion rate of PLF, but it is slightly better than the ABG group.

Mid-term results of giant cell tumours with pathologic fractures around the knee: a multicentre retrospective study.

OBJECTIVE: The aims of this work are to present a classification of "complex fracture" and "simple fracture", to compare their features, treatments and prognosis in patients with giant cell tumour with pathologic fractures around the knee, and to determine the best surgical method for patients who have giant cell tumour around the knee with different degrees of fracture. METHODS: Data from 130 patients with pathologic fractures from giant cell tumour around the knee who underwent surgical treatment from March 2000 to November 2015 at 6 institutes around China were collected and analysed. A multicentric study design was used to explore the epidemiological features and to compare differences in the surgical procedures and prognosis of the two fracture groups. The mean age at diagnosis was 37.1 years old (range, 13-77 years). The median follow-up was 126.5 months, ranging from 68 to 370 months. RESULTS: The general clinical and imaging features of the groups of patients with simple and complex fractures, namely, sex, age, the lesion site, living or working environment, eccentric growth patterns, Campanacci grading system, and duration of symptoms before treatment, showed varying degrees of differences, but with no statistical significance (p > 0.05). The incidence rate of surrounding soft tissue mass was 35.2% (32/91) in the group with simple fractures, whereas it was 87.2% (34/39) in the group with complex fractures, which showed a significant difference (p < 0.05). Wide resection and reconstruction with joint replacement were performed more often in patients with complex fractures (61.5%, 24/39). Intralesional procedures were performed more often in patients with simple fractures (56.0%, 51/91). The difference showed significant differences (p < 0.05). The local recurrence rate was 17.6% (16/91) in the group with simple fractures, whereas it was 10.3% (4/39) in the complex fracture group, showing a significant difference (p < 0.05). A total of 2.3% of patients (n = 3,3/130) developed a skip lesion. The complication rates were 4.6% (4/87) and 14.7% (5/34), respectively, in the two groups with simple or complex fractures, showing a significant difference (p < 0.05). The mean MSTS and TESS scores with simple fractures were 26.6 (range, 13-30) and 84.1 (range, 29-100), respectively, whereas the mean scores in the group with complex fractures were 25.5 (range, 18-30) and 78.3 (range, 30-100), respectively, also showing a significant difference (p < 0.05). CONCLUSION: Our classification of "simple fracture" and "complex fracture" could guide decisions regarding the best surgical method for lesions in patients who have giant cell tumour around the knee with different degrees of fracture.

A novel tool for predicting the survival of endoprosthesis used for reconstruction of the knee following tumor resection: a retrospective cohort study.

BACKGROUND: Prosthesis-related complications, after knee reconstruction with endoprosthesis during operation for tumors around the knee, remain an unresolved problem which necessitate a revision or even an amputational surgery. The purpose of the current study was to identify significant risk factors associated with implant failure, and establish a novel model to predict survival of the prosthesis in patients operated with endoprostheses for tumor around knee. METHODS: We retrospectively reviewed the clinical database of our institution for patients who underwent knee reconstruction due to tumors. A total of 203 patients were included, including 123 males (60.6%) and 80 (39.4%) females, ranging in age from 14 to 77 years (mean: 34.3 ± 17.3 years). The cohort was randomly divided into training (n = 156) and validation (n = 47) samples. Univariable COX analysis was used for initially identifying potential independent predictors of prosthesis survival with the training group (p < 0.150). Multivariate COX proportional hazard model was selected to identify final significant prognostic factors. Using these significant predictors, a graphic nomogram, and an online dynamic nomogram were generated for predicting the prosthetic survival. C-index and calibration curve were used for evaluate the discrimination ability and accuracy of the novel model, both in the training and validation groups. RESULTS: The 1-, 5-, and 10-year prosthetic survival rates were 94.0, 90.8, and 83.0% in training sample, and 96.7, 85.8, and 76.9% in validation sample, respectively. Anatomic sites, length of resection and length of prosthetic stem were independently associated with the prosthetic failure according to multivariate COX regression model (p<0.05). Using these three significant predictors, a graphical nomogram and an online dynamic nomogram model were generated. The C-indexes in training and validation groups were 0.717 and 0.726 respectively, demonstrating favourable discrimination ability of the novel model. And the calibration curve at each time point showed favorable consistency between the predicted and actual survival rates in training and validation samples. CONCLUSIONS: The length of resection, anatomical location of tumor, and length of prosthetic stem were significantly associated with prosthetic survival in patients operated for tumor around knee. A user-friendly novel online model model, with favorable discrimination ability and accuracy, was generated to help surgeons predict the survival of the prosthesis.

Comparison of Outcomes Following TiRobot-Assisted Sacroiliac Screw Fixation with Bone Grafting and Traditional Screw Fixation without Bone Grafting for Unstable Osteoporotic Sacral Fracture: A Single-Center Retrospective Study of 33 Patients.

BACKGROUND This retrospective study from a single center aimed to compare patient outcomes following TiRobot-assisted sacroiliac screw fixation and bone grafting with traditional screw fixation without bone grafting in 33 patients with unstable osteoporotic sacral fracture (UOSF). MATERIAL AND METHODS Patients with UOSF were included and divided into 2 groups: a TiRobot-assisted surgical group with 18 patients (robot-aided sacroiliac screw fixation and bone grafting) and a standard surgical group with 15 patients (free-hand screw fixation without bone grafting). T values of bone mineral density (BMD) £-2.5 standard deviation (SD) were diagnosed as osteoporosis. Screw positioning and fracture healing time were evaluated. Functional outcomes were investigated at the final follow-up. RESULTS There were no statistically significant differences in screw positioning; however, there were satisfactory positioning rates in 94.4% (17/18) of patients in the TiRobot-assisted surgical group and 73.3% (11/15) in the standard surgical group. The advantages with TiRobot on surgical time of screw placement, fluoroscopy frequency, and total drilling times were noted (P=0.000). The nonunion rates were 5.6% (1/18) in the TiRobot-assisted surgical group and 33.3% (5/15) in the standard group (P=0.039). Healing time in the union cases had a significant difference (P=0.031). Functional outcome scores in the TiRobot-assisted surgical group were superior to that in the standard group (P=0.014). CONCLUSIONS The findings showed that TiRobot-assisted sacroiliac screw fixation and bone grafting was a safe and effective surgical treatment option that had a reduced radiation dose and improved fracture healing, when compared with standard screw fixation without bone grafting.

Comparative assessment of biomechanics induced by hinge knee prostheses with two different motion axial system.

We aimed to evaluate the biomechanical contact characteristics of rotating hinge knee (RHK) prostheses with different motion axial systems. We performed finite element (FE) analyses to investigate and compare the peak contact stress and contact location on tibial insert and bushing during a gait cycle. The biaxial (BA) system and spherical center axial (SA) system RHK prostheses were included in this study. The comparisons between experimental tests and FE analyses were performed to verify the validation of FE models. Decreased ISO loadings were then applied to the validated FE models to investigate the peak contact stress and contact location on tibial insert and bushing. The contact areas obtained from experimental tests and FE analyses were in a good agreement. The peak contact stresses on tibial insert and bushing of BA prosthesis were higher than those of SA prosthesis. The contact locations on the superior surface of tibial insert in SA and BA prostheses were at the middle-posterior and posterior side, while those on the rotating axial surface were at the medial and lateral sides, respectively. This study indicate that the tibial insert and bushing of an SA prosthesis have lower peak contact stresses and better contact locations than those of a BA prosthesis during a gait cycle, which may decrease the risk of long-term complications of RHK prostheses. Future studies should be performed to confirm the relationship between the contact characteristics and wear in RHK prostheses.

A novel alginate localization molding technique for cross-sectional area measurement of human tendon to access biomechanical properties.

Accurate determination of the biomedical properties of connective tissue such as tendons and ligaments is dependent on the accurate measurement of their cross-sectional area (CSA). To date, techniques for determining cross-sectional areas of ligaments and tendons have been less than ideal due to their complex geometries and their deformations under external load. A novel non-destructive technique has been developed for determining the cross-sectional area of tendon by locating the tendon rupture, in which aqueous rapid curing alginate dental molding materials, digital photography and computerized image analysis are utilized. This technique marks tendons and alginate molds at 1 cm interval and then tendons are taken out for tensile test. Real-time video is recorded to locate the position of tendon rupture. The corresponding alginate slice is found and then analysis through computer image processing software to obtain a more accurate CSA at tendon rupture, which can be used to calculate the stress and young's modulus of tendon. The accuracy of this technique has been investigated and comparisons have been made with the alginate un-localization molding technique and ellipse estimation technique. Results show this technique can provide accurate CSA values (within 2%) and great reproducibility (coefficient of variation = 0.8%). The technique is non-destructive, can obtain morphological information of soft tissue and can detect cavities.

Efficacy and safety of bone substitutes in lumbar spinal fusion: a systematic review and network meta-analysis of randomized controlled trials.

PURPOSE: A variety of alternative grafts to autologous iliac crest bone (ICBG) have been developed for lumbar spondylodesis, due to frequent complications following ICBG harvest. The optimal alternative graft to ICBG, however, remains elusive till now. The purpose of this study was to compare the efficacy and safety of fusion materials in lumbar degeneration diseases and to provide a ranking spectrum of the grafts. METHODS: Randomized controlled trials (RCTs) comparing different bone grafts in lumbar arthrodesis were eligible for inclusion. A network meta-analysis was performed for endpoints including fusion rate and incidence of adverse events. RESULTS: Twenty-seven RCTs involving 2488 patients and 13 available interventions were included. rhBMP-2 provided the highest fusion rate, being significantly superior to that of ICBG (OR = 0.21, p < 0.001), autograft local bone (ALB) (OR = 0.18, p = 0.022), rhBMP-7 (OR = 0.15, p < 0.001), allograft (OR = 0.13, p = 0.009), and DBM + ALB (OR = 0.07, p = 0.048). The treatment efficacy of allograft could be significantly enhanced by bone marrow concentrate (BMC) supplying (OR = 0.16, p = 0.010). ICBG ranks second on the frequency of complications, which is significantly higher than that of allograft (OR = 0.14, p = 0.041) and ALB (OR = 0.14, p = 0.030). All of the other comparisons showed similar efficacy and safety profiles between groups. CONCLUSION: Ranking spectrums of the efficacy and safety for various bone grafts were provided graphically. Though rhBMP-2 was of the highest success rate, the application should be taken with proper caution because of the widely proposed life-threatening adverse events. ALB, ALB plus synthetic ceramic materials and allograft mixed with BMC were also proved to be potentially effective alternative graft to ICBG. These slides can be retrieved under Electronic Supplementary Material.

Predictive Value of the Nomogram Model in Patients With Megaprosthetic Failure Around the Knee: A Retrospective Analysis.

BACKGROUND: Megaprosthetic replacement is one of the main methods for reconstructing mega bone defects after tumor resection. However, the incidences of complication associated with tumor prostheses were 5-10 times higher than that of conventional total knee arthroplasty. The objective of this study is to establish and validate a nomogram model which can assist doctors and patients in predicting the prosthetic survival rates. METHODS: Data on cancer patients treated with tumor prosthesis replacements at our institution from November 2001 to November 2017 were collected. The potential risk factors which were well-studied and shown to be associated with megaprosthetic failure were analyzed. A nomogram model was established using independent risk factors screened out by multivariate regression analysis. The concordance index and calibration curve were selected for internal validation of the predictive accuracy of nomogram. RESULTS: The 3-, 5-, 10-, and 15-year prosthetic survival rates were 92.8%, 88.6%, 74.1%, and 48.3%, respectively. The prosthetic motion mode, body mass index, type of reconstruction, type of prosthesis, and length of bone resection were independent risk factors for tumor prosthetic failure. A nomogram model was established using these significant predictors, with a concordance index of 0.77 and a favorable consistency between predicted and actual prosthetic failure rate according to the internal validation, indicating that the nomogram model had acceptable predictive accuracy. CONCLUSION: The prediction model identifies high-risk patients for whom attached preventive measures are required. Future studies regarding reduction in incidence of prosthetic failure should attach importance to these high-risk patients.

The influence of donor and recipient characteristics on allograft tendons: a systematic review.

Tendon allograft has been an important alternative graft option aside from autograft. The outcome of reconstruction surgery is determined by donor and recipient related factors. The purpose of this article was to identified all studies reporting donor and recipient characteristics, including the age and gender of donors, along with the age, gender, activity level and smoking status of recipients, that affect the biomechanical properties and post-transplantation outcomes of allograft tendons. The systematic study search was based on MEDLINE via PubMed, Embase and the Cochrane Library databases. The reference lists of the included studies were used for hand searching (snowballing). The searching process was performed by two independent investigators, using search MESH term: "tendon", "allograft", and "person". Studies evaluating the influence of donor and recipient biological characteristics on the mechanical property and transplantation outcome of allograft were included. A total of 12 studies were selected for qualitative synthesis, including 6 studies evaluated the influence of donor characteristics, including age and gender, on the mechanical strength of tendon allograft. 6 studies assessed the influence of recipient characteristics, including age, gender, smoking status, and activity level, on the clinical outcome. As a conclusion, tendon allografts from donor younger than 40 years old were expected to have a higher mechanical property. Young patients or patients with a high level of activity were not recommended to receive allograft tendon when autograft is optional. There is no strong evidence supporting that neither donor or recipient gender affects the tendon allograft transplantation outcomes. Smoking history could increase the risk of complications.

The effects of length of femoral stem on aseptic loosening following cemented distal femoral endoprosthetic replacement in tumour surgery.

PURPOSE: Aseptic loosening is a common prosthetic failure mode. The purpose of this study was to identify dose-response relationship between length of femoral stem and aseptic loosening. METHODS: We collected data of patients who underwent distal femoral prosthetic replacements at our institution from 2001 to 2017. Cox regression and two-piecewise regression model were used to analyze the associations between stem length and aseptic loosening. RESULTS: Significant association of length of femoral stem with aseptic loosening was observed in multivariate model and a non-linear relationship could be found from the smoothed curve. In two-piecewise model, an inflection point was calculated to be 143 mm. On the left of the inflection point, every 1 mm increase in the length of stem indicated that the risk of aseptic loosening could be reduced by 6%. CONCLUSION: There was a significant non-linear relationship between the length of femoral stem and aseptic loosening, and the inflection point was 143 mm.

Network meta-analysis of knee outcomes following anterior cruciate ligament reconstruction with various types of tendon grafts.

PURPOSE: Various grafts were selected for restoring knee stability and regaining pre-injury activity levels after anterior cruciate ligament (ACL) rupture. This review aimed to compare the short-term knee outcomes of different tendon grafts for primary ACL reconstruction (ACLR). METHODS: Databases of PubMed, Embase, and CENTRAL were retrieved for identifying the published RCT comparing the short-term (≤ 2 years) knee outcomes of different tendon grafts for ACLR. The main outcomes include the International Knee Documentation Committee (IKDC) subjective and objective scores, side-to-side difference on knee laxity, Lachman test, pivot-shift test, Lysholm score, Tegner score, all recorded complications and graft re-ruptures. RESULTS: A total of 32 trials involving 2962 patients and 17 grafts were included. Superior IKDC subjective score was found for quadriceps tendon autograft (QTB) when compared with autografts including bone-patellar tendon-bone (BPTB), four-strand hamstring tendon (4S-HT), and double-bundle HT. The 4S-HT autograft was associated with poorer anteroposterior and rotational knee stability than the BPTB autograft. Artificial ligament also was found to provide lower knee stability compared with the autografts including the BPTB, patellar tendon, 4S-HT, 4S-HT with preserved tibial insertion, 6S-HT, and four-strand semitendinosus tendon. Additionally, the BPTB allograft showed a statistically higher knee laxity than 6S-HT allograft, while no difference was found between the genuine autografts and non-irradiated allografts. CONCLUSIONS: QTB was recommended to be used even over the BPTB and 4S-HT autografts. BPTB autograft was more effective on restoring the knee stability than 4S-HT autograft. Non-irradiated allografts could be safely used as alternatives to autografts. However, artificial ligaments were not recommended for primary ACLR for significantly increased risk of knee laxity.