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Purpose: The purpose of this study is to identify the rate and risk factors for a reoperation for arthrofibrosis following primary anterior cruciate ligament (ACL) reconstruction. Methods: Prospective data recorded in the New Zealand ACL Registry were cross‐referenced with data from the Accident Compensation Corporation (ACC). Primary ACL reconstructions performed between April 2014 and May 2021 were analysed. The ACC database was used to identify patients who underwent a reoperation for a diagnosis of arthrofibrosis. Multivariable survival analysis was performed to compute adjusted hazard ratios (aHR) and 95% confidence intervals. Results: A total of 12,296 primary ACL reconstructions were analysed, of which 230 underwent a reoperation for arthrofibrosis (1.9%) at a mean follow‐up of 3.6 years. A higher risk of arthrofibrosis was observed in females (aHR = 1.76, p = 0.001), patients with a history of previous knee surgery (aHR = 1.82, p = 0.04) and when a transtibial drilling technique was used (aHR = 1.53, p = 0.03). ACL reconstruction >6 months after injury had the lowest rate of arthrofibrosis (1.3%, aHR = 0.45, p = 0.01). There was no difference in risk between early surgery within 6 weeks versus delayed surgery between 6 weeks and 6 months after injury (2.9% versus 2.1%, aHR = 0.78, not significant). Conclusion: Female sex, previous knee surgery and a transtibial drilling technique increased the risk of reoperation for arthrofibrosis. Early surgery within 6 weeks of injury was not associated with an increased risk when compared with surgery between 6 weeks and 6 months after injury. Level of Evidence: Level III. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament (ACL) injuries are historically thought to be a result of a single acute overload or traumatic event. However, recent studies suggest that ACL failure may be a consequence of fatigue damage. Additionally, the remodeling response of ACLs to fatigue loading is unknown. Therefore, the objective of this study was to investigate the remodeling response of ACLs to cyclic loading. Furthermore, given that women have an increased rate of ACL rupture, we investigated whether this remodeling response is sex specific. ACLs were harvested from male and female New Zealand white rabbits and cyclically loaded in a tensile bioreactor mimicking the full range of physiological loading (2, 4, and 8 MPa). Expression of markers for anabolic and catabolic tissue remodeling, as well as inflammatory cytokines, was quantified using quantitative reverse transcription polymerase chain reaction. We found that the expression of markers for tissue remodeling of the ACL is dependent on the magnitude of loading and is sex specific. Male ACLs activated an anabolic response to cyclic loading at 4 MPa but turned off remodeling at 8 MPa. These data support the hypothesis that noncontact ACL injury may be a consequence of failed tissue remodeling and inadequate repair of microtrauma resulting from elevated loading. Compared to males, female ACLs failed to increase anabolic gene expression with loading and exhibited higher expression of catabolic genes at all loading levels, which may explain the increased rate of ACL tears in women. Together, these data provide insight into load‐induced ACL remodeling and potential causes of tissue rupture. [ABSTRACT FROM AUTHOR]

Background: The bone–patellar tendon–bone (BTB) autograft is associated with difficulty with kneeling after anterior cruciate ligament (ACL) reconstruction; however, it is unclear whether it results in a more painful or symptomatic knee compared with the hamstring tendon autograft. Purpose: To identify the rate and risk factors for knee pain and difficulty with kneeling after ACL reconstruction. Study Design: Cohort study; Level of evidence, 3. Methods: Primary ACL reconstruction procedures prospectively recorded in the New Zealand ACL Registry from April 2014 to May 2021 were analyzed. The Knee injury and Osteoarthritis Outcome Score (KOOS) was used to identify patients reporting consequential knee pain (CKP), defined as a KOOS Pain subscore of ≤72 points, and severe kneeling difficulty (SKD), defined as a self-report of "severe" or "extreme" difficulty with kneeling. Absolute values of the KOOS Pain and Symptoms subscales were also compared. Results: A total of 10,999 patients were analyzed. At 2-year follow-up, 9.3% (420/4492) reported CKP, and 12.0% (537/4471) reported SKD. The most important predictor of CKP at 2-year follow-up was having significant pain before surgery (adjusted odds ratio, 4.10; P <.001). The most important predictor of SKD at 2-year follow-up was the use of a BTB autograft rather than a hamstring tendon autograft (21.3% vs 9.4%, respectively; adjusted odds ratio, 3.12; P <.001). There was no difference between the BTB and hamstring tendon grafts in terms of CKP (9.9% vs 9.2%, respectively; P =.494) or in absolute values of the KOOS Pain (mean, 88.7 vs 89.0, respectively; P =.37) and KOOS Symptoms (mean, 82.5 vs 82.1, respectively; P =.49) subscales. Conclusion: At 2-year follow-up after primary ACL reconstruction, 9.3% of patients reported CKP, and 12.0% reported SKD. The BTB autograft was associated with difficulty with kneeling, but it did not result in a more painful or symptomatic knee compared with the hamstring tendon autograft. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to identify the risk factors for meniscal repair failure following concurrent primary anterior cruciate ligament (ACL) reconstruction. Methods: Prospective data recorded by the New Zealand ACL Registry and the Accident Compensation Corporation were reviewed. Meniscal repairs performed during concurrent primary ACL reconstruction were included. Repair failure was defined as a subsequent reoperation involving meniscectomy of the repaired meniscus. Multivariate survival analysis was performed to identify the risk factors for failure. Results: A total of 3,024 meniscal repairs were analysed with an overall failure rate of 6.6% (n = 201) at a mean follow-up of 2.9 years (SD 1.5). The risk of medial meniscal repair failure was higher with hamstring tendon autografts (adjusted HR [aHR] = 2.20, 95% CI 1.36–3.56, p = 0.001), patients aged 21–30 years (aHR = 1.60, 95% CI 1.30–2.48, p = 0.037) and in patients with cartilage injury in the medial compartment (aHR = 1.75, 95% CI 1.23–2.48, p = 0.002). The risk of lateral meniscal repair failure was higher in patients aged ≤ 20 years (aHR = 2.79, 95% CI 1.17–6.67, p = 0.021), when the procedure was performed by a low case volume surgeon (aHR = 1.84, 95% CI 1.08–3.13, p = 0.026) and when a transtibial technique was used to drill the femoral graft tunnel (aHR = 2.30, 95% CI 1.03–5.15, p = 0.042). Conclusion: The use of a hamstring tendon autograft, younger age and the presence of medial compartment cartilage injury are risk factors for medial meniscal repair failure, whereas younger age, low surgeon volume and a transtibial drilling technique are risk factors for lateral meniscal repair failure. Level of evidence: Level II. [ABSTRACT FROM AUTHOR]

BACKGROUND: The two methods commonly used for preparing animal models of knee osteoarthritis are surgical trauma and intra-articular injection of protease. However, the models induced by intra-articular injection of drugs are not stable, the traditional surgical modeling method has great damage to the knee joint, and the modeling process differs greatly from the development of clinical knee osteoarthritis. OBJECTIVE: To evaluate the best preparation method for the animal model of knee osteoarthritis through establishing a rabbit knee osteoarthritis model by injuring the knee joint in different surgical ways. METHODS: Sixteen male New Zealand white rabbits aged 5-6 months were randomly divided into sham operation group, model group A, model group B and model group C, with four rats in each group. In the sham operation group, the medial side of the right knee joint was incised and immediately sutured. In the model group A, the meniscus and anterior cruciate ligament of the right knee were worn. In the model group B, the meniscus of the right knee joint was removed and the anterior cruciate ligament of the right knee was worn. In the model group C, the right knee meniscus was removed and the anterior cruciate ligament of the right knee joint was transected. Antibiotics were injected for 3 consecutive days after operation, and the general conditions were recorded. After 4 weeks, the knee joints were observed by X-ray, the changes of cartilage tissue were observed by hematoxylin-eosin staining, and the levels of inflammatory factors in the synovial fluid and serum of the right knee were detected by enzyme-linked immunosorbent assay. RESULTS AND CONCLUSION: Redness, swelling and heat pain were evident in the right knee joint of the model group, and the skin temperature in the model groups was significantly higher than that in the sham operation group. Postoperative skin temperature of the right knee joint in the model groups was significantly higher than that in the sham operation group (P < 0.05). The X-ray observation showed no abnormalities in the knee joint in the sham operation group, while the model groups showed varying degrees of articular surface destruction and joint space narrowing, with the model group C being the most severe. Hematoxylin-eosin staining showed normal cartilage tissue in the sham-operated group, while the model groups showed a reduction in the number of chondrocytes with disordered structural levels. In the model group C, the cartilage structure was seriously damaged with angiogenesis being visible. Enzymelinked immunosorbent assay showed that serum inflammatory factor levels in the model groups were significantly higher than those in the sham operation group (P < 0.05). The level of inflammatory factors in the synovial fluid of the right knee joint was significantly higher in the model groups than the sham operation group (P < 0.05). To conclude, through the analysis of the general condition, imaging and related factors of the knee joint of each group, it was found that the above three surgical methods of the knee injury could successfully construct the rabbit knee osteoarthritis model. The model group C reached the middle and late stage of knee osteoarthritis and the model groups A and B were consistent with the changes in early and middle knee osteoarthritis. In addition, this experiment confirmed that the speed of knee osteoarthritis progression is positively correlated with the degree of knee injury, and the level of inflammatory factors in serum is more sensitive to the changes of knee osteoarthritis than that in the synovial fluid. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the functional and graft survivorship outcomes of the three most common autograft options for primary anterior cruciate ligament reconstruction (ACLR)—hamstring tendon (HT), bone-patella-tendon-bone (BPTB), and quadriceps tendon (QT). Methods: Patients captured by the New Zealand ACL registry who underwent a primary ACLR from 2014 to 2020 were considered for the study. Patients with associated knee injury (including meniscus, chondral, osseous, and additional ligamentous injury) and previous knee surgery were excluded. Comparison was made between HT, BPTB, and QT autografts with respect to Marx and KOOS (Knee Osteoarthritis Outcome Score) scores at minimum 2 years follow-up. In addition, graft survivorship was evaluated by comparing all-cause revision per 100 graft years and revision-free proportion at 2 years post-surgery. Results: 2,582 patients (1,921 HT, 558 BPTB, 107 QT) were included in the study. Differences in adjusted functional outcomes between HT and BPTB were found at 12 months (mean Marx; HT 6.2; BPTB 7.1; P < 0.001) (mean KOOS Sport and Recreation; HT 75.1; BPTB 70.5; n.s.) and 24 months (mean KOOS Sports and Recreation; HT 79.2; BPTB 73.9; P < 0.001). QT was comparable to HT and BPTB in all functional scores at 12 months and 2 years. No statistically significant differences were found in revision rate between all three autograft groups up to 2 years post-surgery (revision rate per 100 graft years; HT 1.05; BPTB 0.80; QT 1.68; n.s. HT vs. BPTB; n.s. HT vs. QT; n.s. QT vs. BPTB). Conclusions: QT was found to be comparable to both HT and BPTB in all functional scores and revision rates up to 2 years post-surgery. Level of evidence: Level III. [ABSTRACT FROM AUTHOR]

Purpose: To validate the New Zealand Anterior Cruciate Ligament (ACL) Registry's capture rate of revisions by cross-referencing Registry data with reoperations data recorded by the Accident Compensation Corporation (ACC) and identify risk factors for all-cause reoperation., Methods: Primary ACL reconstructions performed between April 2014 and September 2019 were individually matched on a record-by-record basis between the two databases. The ACC database was used to identify patients who underwent a reoperation with manual review of operation notes to identify whether a revision or other procedure was performed. This was combined with the number of revisions separately recorded in the New Zealand ACL Registry, which was used as the denominator value to calculate the Registry's capture rate of revisions. Patient and surgical data recorded in the Registry were analysed to identify independent predictors for all-cause reoperation., Results: A total of 8046 primary ACL reconstructions were matched between the New Zealand ACL Registry and the ACC databases. The reoperation rate was 8.9% (n = 715) at a mean follow-up of 2.5 years. Meniscal-related procedures were the most common reoperation (n = 299, 3.7%), followed by revision ACL reconstruction (n = 219, 2.7%), arthrofibrosis (n = 185, 2.3%), cartilage (n = 56, 0.7%) and implants (n = 32, 0.4%). The New Zealand ACL Registry captured 96% of revisions. Younger age (hazard ratio [HR] > 1.4, p < 0.001), earlier surgery (HR > 1.3, p = 0.05), concurrent meniscal repair (medial meniscus HR = 1.9, p < 0.001 and lateral meniscus HR = 1.3, p = 0.022) and hamstring tendon autografts (HR = 1.4, p = 0.001) were associated with a higher risk of reoperation., Conclusion: The New Zealand ACL Registry captured 96% of revisions. Risk factors for all-cause reoperation included younger age, earlier surgery, meniscal repair and hamstring tendon autografts., Level of Evidence: Level III., (© 2024 The Author(s). Knee Surgery, Sports Traumatology, Arthroscopy published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Simple Summary: Osteoarthritis is an incurable chronic disease. For this reason, new therapies are constantly emerging to improve clinical signs and the quality of life of our pets. Chondroitin sulfate, glucosamine and hyaluronic acid have been proven effective and are the most widely used in many formulations. In the present study, adding native type II collagen to the combination of chondroitin sulfate, glucosamine and hyaluronic acid showed improvements on osteoarthritis progression in an experimental model of osteoarthritis induced by transection of the cranial cruciate ligament of the knee in New Zealand white rabbits. Disease progression was monitored at different time points using magnetic resonance imaging biomarkers, measurement of hyaluronic acid in synovial fluid, and macroscopic and microscopic evaluations of cartilage, synovial membrane and subchondral bone. Overall, our results showed that adding native type II collagen to a combination of glycosaminoglycans allows a significantly slower osteoarthritis progression, compared to glycosaminoglycans alone. A prospective, experimental, randomized, double blinded study was designed to evaluate the effects of glycosaminoglycans, with or without native type II collagen (NC), in an osteoarthritis model induced by cranial cruciate ligament transection. The following compounds were tested: chondroitin sulfate (CS), glucosamine hydrochloride (GlHCl), hyaluronic acid (HA) and NC. Fifty-four female 12-week-old New Zealand rabbits were classified into three groups: CTR (control–no treatment), CGH (CS + GlHCl + HA) and CGH-NC (CS + GlHCl + HA + NC). Each group was subdivided into three subgroups according to survival times of 24, 56 and 84 days. Over time, all rabbits developed degenerative changes associated with osteoarthritis. CGH-NC showed significantly improved values on macroscopic evaluation, compared to CTR and CGH. Microscopically, significantly better results were seen with CGH and CGH-NC, compared to CTR, and synovial membrane values were significantly better with CGH-NC compared to CGH. A significant improvement in magnetic resonance imaging biomarkers was also observed with CGH-NC in cartilage transversal relaxation time (T2) and subchondral bone D2D fractal dimension in the lateral condyle. In conclusion, our results show beneficial effects on joint health of CGH and CGH-NC and also supports that adding NC to CGH results in even greater efficacy. [ABSTRACT FROM AUTHOR]

Background: The hamstring tendon is frequently used to reconstruct the anterior cruciate ligament (ACL), but there is a lack of consensus on the optimal method of fixation. Registry studies have shown that the type of femoral fixation device can influence the risk of revision ACL reconstruction (ACLR), but it is unclear whether the type of tibial fixation has an effect. In New Zealand, over 95% of hamstring tendon grafts are fixed with an adjustable loop suspensory device on the femoral side, with variable usage between suspensory and interference devices, with or without a sheath, on the tibial side. Purpose: To investigate the association between the type of tibial fixation device and the risk of revision ACLR. Study Design: Cohort Study; Level of evidence, 2. Methods: Prospective data recorded in the New Zealand ACL Registry were analyzed. Only primary ACLRs performed with a hamstring tendon autograft fixed with a suspensory device on the femoral side were included. A Cox regression survival analysis with adjustment for patient factors was performed to analyze the effects of the type of tibial fixation device, the number of graft strands, and graft diameter on the risk of revision. Results: A total of 6145 primary ACLRs performed between 2014 and 2019 were analyzed. A total of 59.6% of hamstring tendon autografts were fixed with a suspensory device on the tibial side (n = 3662), 17.6% with an interference screw with a sheath (n = 1079), and 22.8% with an interference screw without a sheath (n = 1404). When compared with suspensory devices, a higher revision risk was observed when using an interference screw with a sheath (adjusted hazard ratio [HR], 2.05; P =.009) and without a sheath (adjusted HR, 1.81; P =.044). The number of graft strands and a graft diameter of ≥8 mm were associated with the rate of revision on the univariate analysis; however, after adjusting for confounding variables on the multivariate analysis, they did not significantly influence the risk of revision. Conclusion: In this study of hamstring tendon autografts fixed with an adjustable loop suspensory device on the femoral side during primary ACLR, the use of an interference screw, with or without a sheath, on the tibial side resulted in a higher revision rate when compared with a suspensory device. [ABSTRACT FROM AUTHOR]

Background: Bone formation plays an important role in early tendon–bone healing after anterior cruciate ligament reconstruction (ACLR). Dedifferentiated osteogenic bone marrow mesenchymal stem cells (De-BMSCs) have enhanced osteogenic potential. This study aimed to investigate the effect of De-BMSCs transplantation on the promotion of bone formation at the tendon–bone interface after ACLR and to further explore the molecular mechanism of the enhanced osteogenic potential of De-BMSCs. Methods: BMSCs from the femurs and tibias of New Zealand white rabbits were subjected to osteogenic induction and then cultured in medium without osteogenic factors; the obtained cell population was termed De-BMSCs. De-BMSCs were induced to undergo osteo-, chondro- and adipo-differentiation in vitro to examine the characteristics of primitive stem cells. An ACLR model with a semitendinosus tendon was established in rabbits, and the animals were divided into a control group, BMSCs group, and De-BMSCs group. At 12 weeks after surgery, the rabbits in each group were sacrificed to evaluate tendon–bone healing by histologic staining, micro-computed tomography (micro-CT) examination, and biomechanical testing. During osteogenic differentiation of De-BMSCs, an siRNA targeting nuclear factor of activated T-cells 1 (NFATc1) was used to verify the molecular mechanism of the enhanced osteogenic potential of De-BMSCs. Results: De-BMSCs exhibited some properties similar to BMSCs, including multiple differentiation potential and cell surface markers. Bone formation at the tendon–bone interface in the De-BMSCs group was significantly increased, and biomechanical strength was significantly improved. During the osteogenic differentiation of De-BMSCs, the expression of Nanog and NFATc1 was synergistically increased, which promoted the interaction of NFATc1 and Osterix, resulting in increased expression of osteoblast marker genes such as COL1A, OCN, and OPN. Conclusions: De-BMSCs transplantation could promote bone formation at the tendon–bone interface after ACLR and improve the biomechanical strength of the reconstruction. The Nanog/NFATc1/Osterix signaling pathway mediated the enhanced osteogenic differentiation efficiency of De-BMSCs. [ABSTRACT FROM AUTHOR]

Background: In primary anterior cruciate ligament (ACL) reconstruction, a bone–patellar tendon–bone (BTB) autograft is associated with lower ipsilateral failure rates. BTB autografts are associated with a higher rate of contralateral ACL injuries, which some clinicians view as a marker of success of the BTB autograft. However, there is a lack of evidence on whether BTB autografts improve the rate of return to activity and sport. Purpose: To compare the rate of return to preinjury activity levels in high-activity patients after ACL reconstruction with BTB autograft or hamstring tendon autograft. Study Design: Cohort study; Level of evidence, 3. Methods: In a high-activity cohort of patients recorded between 2014 and 2018 in the New Zealand ACL Registry, prospectively collected data on preinjury and postoperative Marx activity scores were analyzed. The proportion of patients who returned to their preinjury activity levels at 1- and 2-year follow-up was compared between graft types. Results: Overall, 11.3% (208/1844) of patients returned to their preinjury activity levels at 1-year follow-up, and 15.5% (184/1190) returned at 2-year follow-up. At 1-year follow-up, 17.2% of patients with a BTB autograft returned to their preinjury activity levels compared with 9.3% of patients with a hamstring tendon autograft (adjusted odds ratio, 1.59 [95% CI, 1.16-2.17]; P =.004). At 2-year follow-up, 23.3% of patients with a BTB autograft had returned to their preinjury activity levels compared with 13.3% of patients with a hamstring tendon autograft (adjusted odds ratio, 1.63 [95% CI, 1.14-2.34]; P =.008). Male sex and younger age were associated with a higher rate of return to activity at both follow-up time points. Conclusion: The use of BTB autografts increased the odds of returning to preinjury activity levels at early follow-up. A higher rate of return to activity is a possible explanation for the higher rate of contralateral ACL injuries with the use of BTB autografts. [ABSTRACT FROM AUTHOR]

BACKGROUND: Due to the close relationship between the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway and the physiological metabolism of bone tissue, human chitinase protein 40 (YKL-40) can regulate the PI3K/Akt signaling pathway related to breast cancer pathogenesis. Therefore, it is speculated that YKL-40 may regulate apoptosis in knee osteoarthritis (KOA) chondrocytes through the PI3K/Akt signaling pathway. OBJECTIVE: To study the mechanism by which YKL-40 regulates apoptosis in rabbit KOA chondrocyte s through the PI3K/Akt signaling pathway. METHODS: (1) New Zealand white rabbits were randomized into two groups. An animal model of KOA was made using anterior cruciate ligament dissection in the model group, whereas the right posterior knee joint capsule was cut but not dissected in the control group. Chondrocytes were extracted from the rabbits at 6 weeks after modeling. Hematoxylin-eosin staining and Mankin histological scoring of the cartilage tissue were performed, whereas immunohistochemical staining was used to detect type II collagen expression in chondrocytes. (2) The second-generation chondrocytes in the control group were used as normal control group, and those in the model group were further divided into four groups, followed by culture with high glucose DMEM medium containing 10% fetal bovine serum in KOA model group, 100 μg/L YKL-40 in KOA + YKL group, 50 μmol/L LY294002 in KOA + LY group, and 50 μmol/L LY294002 + 100 μg/L YKL-40 in KOA + YKL + LY group. The expression levels of collagen type II, matrix metalloproteinase 13, Akt, p-Akt, P53, Bcl-2 proteins in chondrocytes were detected by western blot. RESULTS AND CONCLUSION: Hematoxylin-eosin staining, Mankin histological score, and collagen type II immunohistochemical staining confirmed the successful construction of KOA animal model and successful chondrocyte culture. Compared with the normal control group, the collagen type II, Bcl-2, p-Akt protein expression levels in chondrocytes were significantly reduced in the KOA model group (P < 0.05), and matrix metalloproteinase 13 and P53 protein expression levels were significantly increased in the KOA model group (P < 0.05). Compared with the KOA model group, these indicators were significantly improved in the KOA + YKL group (P < 0.05), significantly worsened in the KOA + LY group (P < 0.05), and had no significant changes in the KOA + YKL + LY group (P > 0.05). However, there were significant differences between the KOA + YKL group and the KOA + LY group (P < 0.05). In addition, the expression level of p-Akt protein in chondrocytes had no difference among groups (P > 0.05). To conclude, YKL-40 can inhibit the apoptosis of KOA chondrocytes, accelerate the repair of KOA cartilage damage and delay the degeneration of cartilage by activating the PI3K/Akt signaling pathway. Therefore, YKL-40 can be used as a new target for clinical treatment of KOA. [ABSTRACT FROM AUTHOR]

Purpose: The use of an accessory anteromedial portal to drill the femoral graft tunnel in primary anterior cruciate ligament (ACL) reconstruction was introduced in the 2000s in an effort to achieve a more anatomic femoral tunnel position. However, some early studies reported an increase in revision ACL reconstruction compared to the traditional transtibial technique. The aim of this study was to analyse recent data recorded by the New Zealand ACL Registry to compare outcomes of ACL reconstruction performed using the anteromedial portal and transtibial techniques. Methods: Analysis was performed on primary isolated single-bundle ACL reconstructions recorded between 2014 and 2018 by the New Zealand ACL Registry. Patients were categorised into two groups according to whether an anteromedial portal or transtibial technique was used to drill the femoral graft tunnel. The primary outcome was revision ACL reconstruction and was compared between both groups through univariate and multivariate survival analyses. The secondary outcomes that were analysed included subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Marx activity score. Results: Six thousand one hundred and eighty-eight primary single-bundle ACL reconstructions were performed using either the anteromedial portal or transtibial drilling techniques. The mean time of follow-up was 23.3 (SD ± 14.0) months. Similar patient characteristics such as mean age (29 years, SD ± 11), sex (males = 58% versus 57%) and time to surgery (median 4 months, IQR 5) were observed between both groups. The rate of revision ACL reconstruction was 2.6% in the anteromedial portal group and 2.2% in the transtibial group (n.s.). The adjusted risk of revision ACL reconstruction was 1.07 (95% CI 0.62–1.84, n.s.). Patients in the anteromedial portal group reported improved scores for subscales of the KOOS and higher Marx activity scores at 1-year post-reconstruction. Conclusion: There was no difference in the risk of revision ACL reconstruction between the two femoral tunnel drilling techniques at short-term follow-up. We observed minor differences in patient-reported outcomes at 1-year follow-up favouring the anteromedial portal technique, which may not be clinically relevant. Surgeons can achieve good clinical outcomes with either drilling technique. Level of evidence: III. [ABSTRACT FROM AUTHOR]

BACKGROUND: Studies have shown that platelet-rich plasma has a strong role in promoting chondrocyte repair and proliferation. OBJECTIVE: To investigate the efficacy of platelet-rich plasma in chondrocyte repair and synovial inflammation inhibition in osteoarthritis. METHODS: The blood samples were extracted from the central artery of the ear in 40 New Zealand white rabbits and platelet-rich plasma was prepared by the method of Hokugo. The platelet, platelet-derived growth factor, transfonning growth factor-~, vascular endothelial growth factor in the peripheral blood and platelet-rich plasma were detected simultaneously. Animal models were made by resection of anterior cruciate ligament and divided into experimental group and control group. In the experimental group, 0.3 ml of platelet-rich plasma was injected once a week for 1 O weeks; in the control group, 0.3 ml of sterile saline was injected once a week for 10 weeks. Gross observation and histological observation of knee joints were perfonned: articular cartilage type 11 collagen and matrix metalloproteinase 13 levels were measured: and Mankin score of the cartilage tissue was perfonned at 2, 4, 6, 8, and 1 O weeks after injection. The study protocol was approved by the Animal Experiment Ethics Committee of Chongqing Medical University. RESULTS AND CONCLUSION: (1) The concentrations of platelet, platelet-derived growth factor, transforming growth factor-β. vascular endothelial growth factor in platelet-rich plasma were 5.5, 4.8, 7.7, and 6.2 times those of the peripheral blood, respectively. And there were significant differences between the platelet-rich plasma and peripheral blood (P < 0.05). (2) From the 6th week, the Mankin score of the experimental group was significantly lower than that of the control group (P < 0.05). (3) The expression of type II collagen protein in the experimental group was significantly higher than that in the control group at the 4th, 6th, 8th and 10th weeks after injection (P < 0.05). The expression of matrix metalloproteinase-13 was significantly lower than that in the control group at the 2nd, 4th, 6th, 8th and 10th week (P < 0.05). All these findings indicate that intra-articular injection of platelet-rich plasma can inhibit the development of osteoarthritis by alleviating synovial inflammation and delaying or blocking the damage of chondrocytes. [ABSTRACT FROM AUTHOR]

Background: The integration of the tendon graft within the bone tunnel is one of the decisive success factors of the Anterior Cruciate Ligament (ACL) reconstruction. In ACL reconstruction that uses tendons as graft, the healing process that occurs in the bone tunnel is healing with fibrotic tissue.Aim: This study aims to determine the role of bone marrow mesenchymal stem cells and vascular endothelial growth factor intraarticularly in improving the biomechanical strength.Methods: This study uses experimental research design by using animal as a testing tool. The animals used in this study are male New Zealand white rabbits (Oryctolagus cuniculus), with the weight ranging of 2000 grams up to 3000 grams.Results: From the experiment, all samples from both treatment and control groups were all evaluated and no post-operative complication was found. At the evaluation time of 3 weeks, the difference between the mean of maximum strain rate between the treatment group and the control group was not statistically significant (p >0.05). At the evaluation time of 6 weeks, it was found that the difference in mean value of the maximum strain load force between the treatment groups versus the group was statistically significant.Conclusions: From this study, it can be concluded that intraarticular BM-MSC and VEGF administration can increase the ultimate tension strength of postoperative graft tendon rosary ACL reconstruction. [ABSTRACT FROM AUTHOR]

Background: The patellar tendon is often considered the "gold standard" graft for reducing the risk of graft rupture after anterior cruciate ligament (ACL) reconstruction. However, its use may also be associated with an increased risk of injury to the contralateral ACL. Purpose: To clarify the association between graft choice and the risk of revision and contralateral ACL reconstruction. Study Design: Cohort study; Level of evidence, 2. Methods: Prospective data captured by the New Zealand ACL Registry between April 2014 and December 2018 were reviewed. All primary ACL reconstructions performed using either a hamstring tendon or patellar tendon autograft were included. Cox regression survival analysis adjusting for patient factors was performed to compare the risk of revision and contralateral ACL reconstruction between the hamstring tendon graft and the patellar tendon graft. Results: A total of 7155 primary ACL reconstructions were reviewed, of which 5563 (77.7%) were performed using a hamstring tendon graft and 1592 (22.3%) were performed using a patellar tendon graft. Patients with a hamstring tendon graft had a revision rate of 2.7% compared with 1.3% in patients with a patellar tendon graft (adjusted hazard ratio [HR], 2.51; 95% CI, 1.55-4.06; P <.001). The patellar tendon graft was associated with an increased risk of contralateral ACL reconstruction compared with the hamstring tendon graft (adjusted HR, 1.91; 95% CI, 1.15-3.16; P =.012). The number needed to treat (NNT) with a patellar tendon graft to prevent 1 revision was 73.6. However, the NNT with a hamstring tendon graft to prevent 1 contralateral reconstruction was 116.3. Conclusion: Use of a patellar tendon graft reduced the risk of graft rupture but was associated with an increased risk of injury to the contralateral ACL. Adequate rehabilitation and informed decision making on return to activity and injury prevention measures may be important in preventing subsequent injury to the healthy knee. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to apply bibliometric tools to Australian and New Zealand orthopaedic publications produced between 2008 and 2018 to identify the most highly cited publications, author and institution collaboration networks and topic trends. Analysis of the literature can highlight areas of emerging interest and knowledge gaps, and direct future research.Methods: A systematic search was conducted using Clarivate Analytics Web of Science. Citation analysis was carried out using Web of Science. Collaboration networks were constructed using chord diagrams. Trends in publication topics were analysed using simple linear regression to find the rate of change of publication volume on each topic.Results: A total of 3097 publications contributed to by 8855 individual authors met inclusion criteria. Across the study period, there was a large increase in the annual volume of publications on the topic of ACL (Anterior Cruciate Ligament) surgery. We also found that collaboration between Australian and New Zealand authors was very low with only 1% (n = 31) of publications including authors from both countries and 0.4% (n = 12) including orthopaedic surgeons or trainees from both.Conclusions: Publications on ACL surgery have increased over the past decade, likely due to the presence of competing surgical approaches and the recently recognized risk of osteoarthritis following ACL reconstruction. The overall collaboration between Australian and New Zealand authors was very low which lends itself to opportunities for future research. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament injuries cause significant morbidity, and may be increasing in incidence as participation in high‐risk sports increases. The aim of this study is to investigate the incidence of anterior cruciate ligament reconstruction (ACLR) surgery in New Zealand, and to analyse changes over time in demographic subgroups. Method: Data were sourced from the Accident Compensation Corporation. Data relating to primary ACLRs performed from 2009 to 2016 were evaluated (n = 20 751). Baseline population estimates were obtained from national census data to calculate the incidence, and results were compared to previous data from 2000 to 2005 (n = 7375). Results: The annual incidence of ACLR for 2009–2016 was 58.2 per 100 000 person‐years and was greater in males than in females (72.2 and 44.9, respectively). This represents a 58% increase when compared with the period 2000–2005 (36.9 per 100 000). The greatest increase was seen in females aged 15–19 years, with the incidence increasing by 120% in the last decade, compared with 53% in females aged 20–24 years. The percentage of injuries caused by sports changed from 65% over 2000–2005 to 76% over 2009–2016, with netball, rugby and football accounting for the highest number of injuries. Conclusion: The incidence of ACLR procedures has increased markedly in New Zealand, and this increase was most pronounced in females aged 15–19 years. A greater proportion of procedures are now due to sport‐related injuries. [ABSTRACT FROM AUTHOR]

Objectives. The objective of the study is to evaluate the chondroprotective activity of Channa striatus (Channa) and glucosamine sulphate (glucosamine) on histomorphometric examinations, serum biomarker, and inflammatory mediators in experimental osteoarthritis (OA) rabbit model. Design. Anterior cruciate ligament transection (ACLT) was performed to induce OA in thirty-three male New Zealand white rabbits and were randomly divided into three groups: Channa, glucosamine, and control group. The control group received drinking water and the Channa and glucosamine groups were orally administered with 51.4 mg/kg of Channa extract and 77.5 mg/kg of glucosamine sulphate in drinking water, respectively, for eight weeks and then sacrificed. The articular cartilage was evaluated macroscopically and histologically using semiquantitative and quantitative methods. Serum cartilage oligomeric matric protein (COMP), cyclooxygenase 2 (COX-2) enzyme, and prostaglandin E2 (PGE2) were also determined. Results. Macroscopic analysis revealed that Channa group have a significantly lower severity grade of total macroscopic score compared to the control (p < 0.001) and glucosamine (p < 0.05) groups. Semiquantitative histology scoring showed that both Channa and glucosamine groups had lower severity grading of total histology score compared to the control group (p < 0.001). In comparison with the control, Channa group had lower histopathological changes in three compartments of the joint compared to glucosamine group which had lower histological scoring in two compartments only. The cartilage thickness, area, and roughness of both Channa (p < 0.05) and glucosamine (p < 0.05) groups were superior compared to the control group. However, the Channa group demonstrated significantly less cartilage roughness compared to the glucosamine group (p < 0.05). Serum COMP levels were lower in both Channa (p < 0.05) and glucosamine (p < 0.05) groups compared to the control group. Conclusion. Both oral administration of Channa extract and glucosamine exhibited chondroprotective action on an ACLT OA-induced rabbit model. However, Channa was superior to glucosamine in maintaining the structure of the cartilage. [ABSTRACT FROM AUTHOR]

High-field micro-magnetic resonance imaging (MRI) scanning may provide additional information for quantitative analysis of graft bone healing processes, thus serving as a promising supplementary method in graft and bone healing evaluation following anterior cruciate ligament reconstruction (ACLR) surgery during preclinical studies. The present study included 12 New Zealand white rabbits that underwent ACLR with polyethylene terephthalate (PET) ligament. At 4, 8, and 16 weeks following surgery, 4 rabbits were euthanized and knee joint samples were harvested for a 7.1T micro-magnetic resonance imaging (MRI) scan. The graft bone tunnel diameter and signal noise ratio (SNR) at the region of interest (ROI) were measured. Hematoxylin-eosin staining was performed at each time point to verify the graft bone healing process in histology. The bone tunnel diameter at the graft tunnel interface decreased over time in both femoral and tibial parts. Notably, the tunnel size was smaller than the diameter of the drilling Kirschner wire that was used to observe the femoral part and proximal site of the tibial part at 16 weeks following surgery. SNR research demonstrated that both the femoral and tibial part PET ligaments selected in the ROI exhibited a marked increase in SNR from the initial 4-week results. The micro-MRI result was consistent with that of histological analysis. Micro-MRI scanning was applied in an animal model that underwent ACL reconstruction surgery with PET ligament, and it was determined that micro-MRI is promising in quantitatively observing graft bone healing processes directly with a focus on graft tunnel distances and SNRs. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to quantify the meniscal root anatomy of the New Zealand white rabbit to better understand this animal model for future in vitro and in vivo joint degeneration studies. Methods: Ten non‐paired fresh frozen New Zealand white rabbit knee stifle joints were carefully disarticulated for this study. Measurements were made for all bony landmarks and ligamentous structure attachment sites on the tibial plateau. The following soft tissue structures were consistently identified in the rabbit stifle joint: the anterior root attachment of the lateral meniscus, the anterior root attachment of the medial meniscus, the anterior cruciate ligament, the posterior root attachment of the medial meniscus, the ligament of Wrisberg, the posterior cruciate ligament, and the posterior meniscotibial ligament. The following bony landmarks were consistently identified: the extensor digitorum longus groove, the medial tibial eminence, the center of the tibial tuberosity, and the lateral tibial eminence. Results: The center of the anterior cruciate ligament and the medial tibial eminence apex were found to be 3.4 ± 0.3 mm (2.9–3.6) and 6.1 ± 0.6 mm (5.1–7.0) respectively from the center of the medical anterior root attachment. The center of the anterior cruciate ligament and the lateral tibial eminence apex were found to be 2.1 ± 0.5 mm (1.2–2.7) and 7.0 ± 0.6 mm (6.4–8.2) respectively from the center of the lateral anterior root attachment. The center of the posterior cruciate ligament and the medial tibial eminence apex were found to be 2.0 ± 0.7 mm (0.5–2.6) and 1.8 ± 0.4 mm (1.2–2.4) respectively from the center of the medial posterior root attachment. Conclusions: This study augments our understanding of the comparative anatomy of the rabbit stifle joint. This information will be useful for future biomechanical, surgical, and in vitro studies utilizing the rabbit stifle as a model for human knee joint degenerative diseases. [ABSTRACT FROM AUTHOR]

Background: Young female athletes are a specific population that is at high risk of primary anterior cruciate ligament (ACL) rupture and subsequent graft failure. Despite large numbers of ACL reconstructions being carried out in young women, there is limited analysis of outcomes in this group, leading to low levels of evidence for graft choice., Purpose: To assess the effect of graft choice on ACL reconstruction failure rates among young women in New Zealand., Study Design: Cohort study; Level of evidence, 2., Methods: Prospective data captured by the New Zealand ACL Registry between April 2014 and March 2022 were reviewed. Young women aged 15 to 20 years were included. The primary outcome measure was ACL graft failure during the study period, with the key independent variable being graft type, either patellar or hamstring tendon autograft. This is presented as the rate per 100 patient-years and is compared between the 2 groups using the hazard ratio generated from a Cox proportional hazards regression. Secondary outcome measures were Marx activity scores and the Knee injury and Osteoarthritis and Outcome Score patient-reported outcome measure., Results: A total of 1261 primary ACL reconstructions in young women aged 15 to 20 years were reviewed. Hamstring tendon grafts were used in 797 (63%) reconstructions and patellar tendon graft in 464 (37%) reconstructions. Patients with a hamstring tendon graft had a graft failure rate of 7.7% compared with 1.1% in patients with a patellar tendon graft (hazard ratio, 6.1; 95% CI, 2.4-15.1; P < .001). The number of failures per 100 person-years was significantly higher in the hamstring group (2.05) compared with the patellar tendon group (0.37). No difference was noted at final follow-up between the hamstring tendon and patellar tendon groups when comparing patient-reported outcome measures during the follow-up period., Conclusion: In the young female population of this study, the use of a patellar tendon graft was associated with reduced risk of graft failure and was not associated with an increase in knee morbidity. This highlights the importance of informed decision-making in this high-risk population when considering ACL reconstruction graft type.

ABSTRACT The hamstring tendon autograft is one of the most commonly used graft choices in Anterior cruciate ligament (ACL) reconstruction. There are conflicting results regarding postoperative hamstring strength deficits in patients who have had a hamstring graft. The semitendinosus tendon has been shown to regenerate after harvesting for ACL autograft, suggesting that the muscle has the potential to regain normal function. However, no studies have been performed to define the microstructural changes that occur in the semitendinosus muscle after tendon resection. In this study, we hypothesized that fatty infiltration of the semitendinosus muscle after tendon harvest in New Zealand White rabbits increases postoperatively and remains constant or increases during the first year of repair. The semitendinosus tendon was unilaterally detached and harvested from 15 rabbits. Five rabbits were sacrificed at 3-, 6-, and 12-month intervals, and the semitendinosus muscle-tendon units were analyzed. The contralateral unoperated limb served as the control. The gross tendon and muscle dimensions and histologic percentage of fatty infiltration were measured. We found no significant difference in fatty infiltration at any time point between the control muscle and test specimens and that there was no progression of fatty infiltration over time. If these results hold true in humans, natural repair of the hamstring muscle following tendon harvest during ACL autograft reconstruction is not inhibited by fatty infiltration. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1234-1239, 2013 [ABSTRACT FROM AUTHOR]

We describe the functional capability of a cross-linked hydrogel composed of sulfated glycosaminoglycans and a cationic cellulose by conducting trials on experimental animal models using intra-articular implants to treat an articular disease called osteoarthritis. Forty-eight mature New Zealand white rabbits were divided into three experimental groups: A, B, and C. Group A and B underwent unilateral anterior cruciate ligament transection (ACLT) of the right knee. Subsequently, both knees of group A were treated with the injectable formulation under study. Meanwhile, group B was treated with sterile PBS (placebo). The animals of group C were surgically operated in both knees: Commercial hyaluronic acid (HA) was implanted in the left knee, and the formulation under study was implanted in the right knee. After implantation, all specimens underwent several evaluations at 3, 6, and 12 months postoperatively. At 6 months, no significant differences were detected between the right and left knees of the different groups. However, significant differences were observed between both knees at 12 months in group C, with less cartilage damage in the right knees implanted with our hydrogel. Therefore, in vivo studies have demonstrated hydrogel safety, superior permanence, and less cartilage damage for long-term follow up 12 months after implantation for the formulation under study compared with commercial HA. [ABSTRACT FROM AUTHOR]

Objective: To investigate the clinical beliefs and practices of New Zealand physiotherapists regarding pre- and post-surgical rehabilitation and return to sport (RTS) criteria following anterior cruciate ligament reconstruction (ACLR)., Design: Online cross-sectional survey., Methods: A survey was adapted from a previously published survey and disseminated to New Zealand physiotherapists who were considered more likely to be involved in post-ACLR rehabilitation., Results: The number of completed surveys was 318. Most physiotherapists (85%) preferred to first consult patients within 14 days of ACLR. In the first six weeks following ACLR, 89% of physiotherapists see patients at least once per week. Between 3- and 6-months post-ACLR, 76% of physiotherapists see patients at least once a fortnight. Pre-operative rehabilitation and post-operative rehabilitation exceeding six months are considered essential or important to patient outcomes by over 95% of physiotherapists. While 63% of physiotherapists support RTS 9-12 months after ACLR, 11% permit RTS within 6-9 months of surgery. Common RTS considerations include functional capacity, movement quality during functional tasks, time from ACLR, and knee strength., Conclusion: The survey revealed variability in the beliefs and practices of NZ physiotherapists regarding post-ACLR rehabilitation, and these beliefs and practices are at times inconsistent with best practice recommendations., Competing Interests: Declaration of competing interest None., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The interference screw fixation method is used to secure a graft in the tibial tunnel during anterior cruciate ligament reconstruction surgery. However, several complications have been reported, such as biodegradable screw breakage, inflammatory or foreign body reaction, tunnel enlargement, and delayed graft healing. Using additive manufacturing (AM) technology, we developed a titanium alloy (Ti6Al4V) interference screw with chemically calcium phosphate surface modification technology to improve bone integration in the tibial tunnel. After chemical and heat treatment, the titanium screw formed a dense apatite layer on the metal surface in simulated body fluid. Twenty-seven New Zealand white rabbits were randomly divided into control and additive manufactured (AMD) screw groups. The long digital extensor tendon was detached and translated into a tibial plateau tunnel (diameter: 2.0 mm) and transfixed with an interference screw while the paw was in dorsiflexion. Biomechanical analyses, histological analyses, and an imaging study were performed at 1, 3, and 6 months. The biomechanical test showed that the ultimate pull-out load failure was significantly higher in the AMD screw group in all tested periods. Micro-computed tomography analyses revealed early woven bone formation in the AMD screw group at 1 and 3 months. In conclusion, AMD screws with bioactive surface modification improved bone ingrowth and enhanced biomechanical performance in a rabbit model. [ABSTRACT FROM AUTHOR]

Healing of an anterior cruciate ligament graft in bone tunnel yields weaker fibrous scar tissue, which may prolong an already prolonged healing process within the tendon–bone interface. In this study, gelatin molecules were added to thermosensitive chitosan/β-glycerol phosphate disodium salt hydrogels to form chitosan/gelatin/β-glycerol phosphate (C/G/GP) hydrogels, which were applied to 0.1 mg/mL collagenase carrier in the tendon–bone junction. New Zealand white rabbit's long digital extensor tendon was detached and translated into a 2.5-mm diameter tibial plateau tunnel. Thirty-six rabbits underwent bilateral surgery and hydrogel injection treatment with and without collagenase. Histological analyses revealed early healing and more bone formation at the tendon–bone interface after collagenase partial digestion. The area of metachromasia significantly increased in both 4-week and 8-week groups after collagenase treatment (p < 0.01). Micro computed tomography showed a significant increase in total bone volume and bone volume/tissue volume in the 8 weeks after collagenase treatment, compared with the control group. Load-to-failure was significantly higher in the treated group at 8 weeks (23.8 ± 8.13 N vs 14.3 ± 3.9 N; p = 0.008). Treatment with collagenase digestion resulted in a 66% increase in pull-out strength. In conclusion, injection of C/G/GP hydrogel with collagenase improves tendon-to-bone healing in a rabbit model. [ABSTRACT FROM AUTHOR]

Evaluating cell migration after cell-based treatment is important for several disorders, including osteoarthritis (OA), as it might influence the clinical outcome. This research explores migrating expanded-adipose stromal cells (ASCs) and adipose niches after enzymatic and mechanical processes. Bilateral anterior cruciate ligament transection induced a mild grade of OA at eight weeks in adult male New Zealand rabbits. ASCs, enzymatic stromal vascular fraction (SVF), and micro fragmented adipose tissue (MFAT) were intra-articularly injected in the knee joint. Assessments of cell viability and expression of specific markers, including CD-163 wound-healing macrophages, were done. Cell migration was explored through labelling with PKH26 dye at 7 and 30 days alongside co-localization analyses for CD-146. All cells showed good viability and high percentages of CD-90 and CD-146. CD-163 was significantly higher in MFAT compared to SVF. Distinct migratory potential and time-dependent effects were observed among cell-based treatments. At day 7, both ASCs and SVF migrated towards synovium, whereas for MFAT versus cartilage, a different migration pattern was noticed at day 30. The long-term distinct cell migration of ASCs, SVF, and MFAT open interesting clinical insights on their potential use for OA treatment. Moreover, the highest expression of CD-163 in MFAT, rather than SVF, might have an important role in directly mediating cartilage tissue repair responses. [ABSTRACT FROM AUTHOR]

The author focuses on Norwegian snowboarder with an anterior cruciate ligament (ACL), meniscal and cartilage injury sustained in New Zealand or Australia while being trained for the Sochi Olympics to be held in 2014. Topics discussed include alpine skiing events, knee ligament registries, and primary prevention programs. It also discusses surgical procedures for improving long-term results.