The Anterior Cruciate Ligament (ACL) plays a vital role in maintaining function and stability in the knee. Over the last several decades, much research has been focused on elucidating the anatomy, structural properties, biomechanics, pathology, and optimal treatments for the ACL. Through careful and objective study, the ACL can be understood to be a dynamic structure, rich in neurovascular supply. Although it is referred to as one ligament, it is comprised of two dis-tinct bundles which function synergistically to facilitate normal knee kinematics. The bony morphology of the knee defines normal knee kinematics, as well as the nature of the soft-tissue structures about the knee. Characterized by individual uniqueness, bony morphology varies from patient to patient. The ACL, which is a reflection of each patient's unique bony morphol-ogy, is inherently subject to both anatomic and morphologic variation as well. Furthermore, the ACL is subject to physiologic aging, which can affect the anatomic and structural properties of the ligament over time. A successful anatomic ACL Reconstruction, which may be considered the functional restoration of the ACL to its native dimensions, collagen orientation, and inser-tion sites according to individual anatomy, considers all these principles. It is vital to respect the nature we observe, rather than to “create” nature to fit a one-size-fits-all surgery. Double bundle ACL Reconstruction may therefore be thought of more as a concept rather than a specific technique, one that respects the individual unique anatomy of each patient to provide a truly indi-vidualized, anatomic, and value-based ACL Reconstruction

The management of symptomatic single bundle Anterior Cruciate Ligament (ACL) ruptures is still a surgical dilemma. Preservation of the intact fibres of the ACL bundle is considered to be a possible source of reinnervation of the ACL autograft which reflects on better proprioceptive knee control after major ligament reconstruction. Results of a prospective study of 67 patients who had a double stranded but single bundle Anterior Cruciate Ligament (ACL) reconstruction for partial ACL ruptures are presented. There were 43 males and 24 females in this study with a mean age at the time of injury of twenty-five years (14 – 40). Eight played sport professionally and thirty-four played at a competitive level. A valgus twisting force was the most common mechanism of injury. Mean injury to operation time was 7.5 weeks (2–12). All procedures were done arthroscopically without using tourniquet, but using an arthroscopy pump and irrigation fluid containing adrenaline. The semitendinosis hamstring graft was used in all reconstructions. The mean follow-up period was 3.3 years (2–5.4). There was one major complication, who developed a reflex sympathetic dystrophy following a saphenous nerve neuroma. The Quality of Life (QOL) score was assessed using the Mohtadi index. The mean pre-operative QOL score of 30 (13–50) was improved to 93 (70–100) post-operatively. Fifty patients were able to return to their previous sporting level at a mean duration of 9 months (6–12). Preservation of mechanoreceptors by performing a double stranded, single bundle ACL reconstruction in partial ACL ruptures in high demand patients yields good results and enables early return to high demand sports

Don O’Donoghue (1950) described a particular acute injury of the knee in athletes (“also of high school age”) that he described as “an unhappy triad”. It consisted of: 1) rupture of the Medial Collateral Ligament (MCL), 2) damage to the Medial Meniscus (MM) and 3) rupture of the Anterior Cruciate Ligament (ACL). We have reviewed the arthroscopic findings of 34 consecutive knees (ages 12 to 16 years) with complete rupture of the ACL. In 21 cases the injury was acute, and the remaining were chronic of had had more than one traumatic episode at the time of arthroscopy. Out of the 34 cases, 26 had associated meniscal injuries: 4 MM; 14 Lateral Meniscus (LM) and 8 MM plus LM. Acute ACL injuries were associated mainly with LM damage (MM/LM: 1/5) whereas, in the chronic injuries, there were no such differences (MM/LM: 1/1). Out of the 21 acute LCA injuries there were 17 cases of acute rupture of the MCL. Conclusions: 1- Contrary to what has been widely accepted, also in pre-adolescent and adolescent, Acute ACL ruptures are more frequently associated with LM damage that with MM tears. 2- Most injuries of the MM associated to ACL injuries (particularly “bucket handle” tears) are the result of a previously ACL unstable knee

Abstract

Purpose: To determine if patients randomized to a knee immobilizer following a primary hamstring tendon anterior cruciate ligament (ACL) reconstruction have lower visual analog scale (VAS) pain scores at day two postoperative than patients who do not wear a knee immobilizer. Method: Patients aged 18–40 with symptomatic ACL deficiency as determined by MRI or physical exam who met the study inclusion criteria were eligible. Patients meeting intra-operative inclusion critiera were randomized (immobilizer or no immobilizer) during wound closure. The immobilizer used was a soft unhinged brace with velcro straps and three metal bars (Breg). Pre, intra and post operative protocols were standardized. Analgesic use and VAS scores were recorded at: one hour after surgery, 8am and 8pm for the first two days postoperative, and 5pm for days 3–14 postoperative. Patients were examined by the surgeon within 14–28 days postoperative. Based on a published survey and the literature, the primary outcome was patient self-assessed pain using a 0–100mm VAS (no pain-worst pain) at day 2 postoperative. Secondary outcomes included: analgesic use, complications, and range of motion. A sample size estimate was calculated resulting in 44 patients per group. A total of 102 patients were enrolled; 88 randomized and 14 excluded intra-operatively. Recruitment was achieved within 11 months. Results: There was no difference in mean VAS pain scores at 2 days post-operative between immobilized and non-immobilized patients (32.6 and 35.2, respectively; p=0.59, 95% CI −6.99, 12.3). Regardless of group allocation, the greatest pain reported was on the evening of day 1 post-operative. Throughout the first week, patients medicated to a pain level of approximately 30/100. There were no differences between groups in medication consumed, range of motion or complications. At 2 days post-operative all patients randomized to the immobilizer group reported that they worn their brace 76–100% of the time. Conclusion: No differences in pain were detected between immobilized and non-immobilized patients at any point during 14 days post ACL reconstruction. Based on these findings, a knee immobilizer is not recommended post-operatively for pain control. This study does not address other reasons for immobilizer use such as graft protection or range of motion

Introduction: The aim of this study was to evaluate whether a guiding pin for a femoral tunnel could be positioned through the tibial tunnel into the center of the anatomical ACL attachment.

Material and Methods: We studied 77 knees who underwented arthroscopic ACL reconstruction with hamstrings. The femoral tunnel was drilled through an antero-medial portal at the center of the anatomic insertion at about 10 resp. 2 o’clock position. Tibial tunnel (mean diameter 7.55 ± 0.54 mm ) was drilled at 90° of knee flexion. The aiming point was on a line, being a “prolongation” of the posterior border of the anterior horn of the lateral meniscus and at exactly 60% of the distance from the end of the anterior horn of the lateral meniscus and the medial tibial spine. Then, through the tibial tunnel, a 4mm offset femoral drill guide was positioned as close as possible to the femoral tunnel and a 2.5 mm guide wire was drilled. The position of the guide wire was photographed arthroscopically and the deviation was measured as distance between the center of the femoral tunnel and guide wire.

Results: The mean angle of the tibial tunnel in the coronar plain was 27,53° and in the sagittal plain 25,84°, both according to the longitudinal axis of the tibia. In 74 knees ( 96. 1 % ) the guidewire did not reach the femoral tunnel. Only in 3 knees it reached the superomedial edge of the femoral tunnel. The mean deviation was 4.50 ± 1.54 mm (p = 0.00000004 ). No statistical relationship was found between deviation and tibial tunnel inclination angles or tibial tunnel diameter.

Conclusion: Transtibial femoral tunnel drilling did not reach the anatomic side of the ACL insertion in most of the cases, even with larger tibial tunnels (for hamstring grafts up to 8.5 mm). Therefore we recommend tibial tunnel drilling through the anteromedial portal.

Abstract

Abstract

INTRODUCTION

ACL retaining (BCR) Total Knee Arthroplasty (TKA) provides more normal kinematics than ACL sacrificing (CR) TKA. However, in the native knee the ACL and the asymmetric shape of the tibial articular surface with a convex lateral plateau are responsible for the differential medial/lateral femoral rollback (medial pivot). Therefore, the hypothesis of this study was that an asymmetric biomimetic articular surface together with ACL preservation would better restore native knee kinematics than retention of the ACL alone. Normal knee kinematics from bi-planar fluoroscopy was used to reverse engineer the tibial articular surface of the biomimetic implant. This was achieved by moving the femoral component through the healthy knee kinematics and removing material from a tibial template.

Introduction and Objective

Objectives: To determine the effectiveness of LIA compared to ACB in providing pain relief and reducing opiates usage in hamstring graft ACL reconstructions.

Introduction: The International Knee Documentation Committee (IKDC) recommends use of the IKDC score to document subjective, objective and functional ACL outcome. To further improve knowledge concerning patient QOL after ACL reconstruction, an additional specific QOL questionnaire was developed. Using a combination of univariate and multivariate analysis the patient factors and surgical factors that influenced QOL 5- years after ACL reconstruction were determined.

Materials: 500 patients operated on for arthroscopic ACL reconstruction at our institution between 1997 and 2001 were prospectively enrolled. Patient psychosocial profile, sport expectations, knee exam, type of graft, associated lesion, type of anesthesia, complications, IKDC, KT 2000 at 6 moths, 1 year and 2 years were recorded. At five years, patients were asked to complete a 5-subscale validated QOL questionnaire for ACL deficiency. A multivariate analysis was performed to identify the factors influencing 5-year QOL.

Results: 203 patients completed the 5-years QOL questionnaire. Responders did not statistically differ from non responders. Patient subjective factors such as: patient expectations, pre-operative symptoms, work-school concerns, recreations concerns, social and psycho-social concerns were significantly (p< 0.05) and independently associated with the five-year QOL results. Objective factors such as meniscus tears and results of the KT 2000 (p< 0.05) were the two surgical factors correlated with 5-year QOL.

Discussion: In this large prospective study, most of the factors influencing the 5-year QOL results after ACL reconstruction were related to patient expectations, psycho-social, symptoms and work-sport concerns. The presence of a meniscus tear and greater KT 2000 laxity also contributed to poorer 5-year QOL results.

ACL deficiency can have detrimental pathological effects on the menisci in the knee. A database review in Quebec over a three-year period was previously reported (Canadian Academy of Sport Medicine, Winnipeg, 2003), which examined the relationship between waiting times for ACL surgery and the requirement of a meniscal procedure. The purpose of this study is to determine if the length of time between an index injury and ACL reconstruction (ACLR) surgery correlates with the incidence of meniscal repair and meniscectomy in Alberta, and to compare the results to those of the Quebec study.

Retrospective study, using procedure and billing codes to search the Alberta Health and Wellness databases for knees undergoing primary ACLR surgery between 2002–2005. Inclusion: Patients sixteen years or older at time of reconstruction. Exclusion: Revision ACLR, duplicate billing and coding, and insufficient database information. For each reconstructed knee, databases were searched for initial injury evaluation date with primary care physician, dates of meniscectomy or meniscal repair procedures, and date of ACLR.

Over a three-year period, there were 3382 primary ACL reconstructions performed in Alberta, 3812 ACLR in Quebec. Of these patients, 2583 in Alberta (76%) and 1722 in Quebec (45%) required a meniscal procedure. On average, Albertans waited 1389 days from injury to ACLR compared to 422 days in Quebec. In Alberta, patients not requiring a meniscal procedure waited 1212 days, patients requiring meniscal repair waited 1143 days, and patients requiring meniscectomy waited 1519 days, compared to 251, 413 and 676 days in Quebec, respectively. Three percent of patients in Alberta had ACLR < three months after injury (114 patients), with 45% requiring meniscectomy. Overall, 61% of patients in Alberta required a meniscectomy for significant meniscal injury, compared to 48% of patients in Quebec. The proportions for each province were statistically significant.

Compared to Quebec, patients in Alberta are waiting longer for ACLR, with only a small proportion of cases being treated acutely. The proportion of patients requiring surgery for significant meniscal injury is also greater in Alberta. The higher proportion of patients in Alberta requiring meniscectomy may be due to the delay in ACLR.

Introduction: Instrumented arthrometry is a widely used technique for the quantification of cruciate ligament laxity. It is used both before and after surgery. The Rolimeter(Aircast, Europe) is used in such scenarios. It has several advantages over its cousins; it is more compact, lighter, less expensive and amenable to sterilization techniques. The other leading arthrometers have however had over 15 years of clinical use and their reliability has been thoroughly assessed. Muellner et al found no significant difference in the intra-tester and inter-tester results obtained on Rolimeter assessment of the knees of un-injured healthy subjects. Our study assessed the inter-tester and intra-tester variability when the Rolimeter is applied to patients with unilateral ACL-deficient knees. It also examines whether the level of experience of the examiner influences the results in this group of patients.

Materials and Methods: Six examiners each examined thirty-three subjects on two occasions. One examiner was medically qualified but had never performed a Lachman or anterior drawer test. Two examiners were qualified physiotherapists who routinely examined knees, but had never used a Rolimeter. One medically qualified examiner was considered to be of intermediate experience.Two examiners were regarded as expert Rolimeter users.For each examination a Rolimeter reading was taken three times with the knee at 30 degrees of flexion and three times at 90 degrees of flexion for both knees.The interval between examinations was at least thirty minutes. All the readings were acquired on the same day. The examiners were blinded to whether the subject was known to be ACL deficient or not. The results of the examinations were entered onto a data-base.Repeated measures analysis of variance was used to test for the effects of the following factors, difference between examiners, reproduction of results between examinations.

Results: There was no significant difference between each set of measures for each subject between examinations (p=0.767), indicating that the measurement procedure was reliable. Measurements were significantly higher in patients with ACL-deficient knees compared to the control group (p< 0.001) confirming the sensitivity of the Rolimeter to help diagnose ACL-deficient knees. The in-experienced examiner’s measurements were lowest and were more reliable. The examiner with the intermediate experience was the most un-reliable. Both experienced examiners were in close agreement.

Conclusion: We have demonstrated that the rolimeter is reliable in the assesment of ACL deficient patients regardless of the experience of the examiner.

Anterior knee instability associated with rupture of ACL is a disabling clinical problem, especially in the athletic individual. The gracilis and semitendinosus tendon (T4) represent an alternative autograft donor material for reconstruction of the ACL.

The aim of our study was to elaborate a CPG to assist physiotherapists in decision making and to improve the efficacy and uniformity of care for patients with ACL reconstruction with T4.

The CPG was developed according to international methods of guideline development. To identify “best evidence” a structured search was performed. When no evidence was available, consensus between experts (physiotherapist and orthopaedic surgeons) was achieved to develop the guideline. To identify “best clinical experience” and “physiopathology reasoning” focus group of practicing physiotherapists was used. They reviewed the clinical applicability and feasibility of the guideline, and their comments were used to improve it.

CPG include three phases determined from the evidence, physiopathology reasoning and the biological process of autograft (weeks after the surgery: 2^a–6^a, 6^a–10^a and 10^a–16^a). The recommendations included: In postoperative weeks (2^a–6^a) physiotherapy focused on early range of motion of the knee; manual therapy (passive range of motion (PROM) 0–120° and miofascial techniques), pulsed ultrasound of low intensity with a power of 0.3w/cm2 (1MHz) during 10min/day in tibial tunnel, early active hamstring beginning with static weight bearing co-contractions (closed-kinetic-chain) and adductors, partial weight bearing with crutches, exercises in the swimming pool and cryotherapy to pain control (30 mi/4 hours). In weeks 6 to 10, full weight bearing, manual therapy (PROM 0–140° and miofascial techniques), hamstring strengthening progress complexity and repetitions of co-contractions, electrotherapy hamstring and quadriceps co-contractions. Starting at week 10, progress to more dynamic activities/movements, proprioceptive work, open-kinetic-chain, stationary bike and Theraband squats. In week 12, progress jogging program and plyometric type activities. The patients performed sports-specific exercises by about 3½ months postoperative.

The December 2022 Sports Roundup. 360. looks at: Anterior cruciate ligament (ACL) repair with dynamic intraligamentary stabilization or anterior ACL at five years?; Femoroacetabular impingement in mild osteoarthritis: is hip arthroscopy the answer?; Steroids in Achilles tendinopathy: A randomized trial

We investigated whether strontium-enriched calcium phosphate cement (Sr-CPC)-treated soft-tissue tendon graft results in accelerated healing within the bone tunnel in reconstruction of the anterior cruciate ligament (ACL). A total of 30 single-bundle ACL reconstructions using tendo Achillis allograft were performed in 15 rabbits. The graft on the tested limb was treated with Sr-CPC, whereas that on the contralateral limb was untreated and served as a control. At timepoints three, six, nine, 12 and 24 weeks after surgery, three animals were killed for histological examination. At six weeks, the graft–bone interface in the control group was filled in with fibrovascular tissue. However, the gap in the Sr-CPC group had already been completely filled in with new bone, and there was evidence of the early formation of Sharpey fibres. At 24 weeks, remodelling into a normal ACL–bone-like insertion was found in the Sr-CPC group. Coating of Sr-CPC on soft tissue tendon allograft leads to accelerated graft healing within the bone tunnel in a rabbit model of ACL reconstruction using Achilles tendon allograft. Cite this article: Bone Joint J 2013;95-B:923–8

Aims

MRI has been suggested as an objective method of assessing anterior crucate ligament (ACL) graft “ligamentization” after reconstruction. It has been proposed that the MRI appearances could be used as an indicator of graft maturity and used as part of a return-to-sport assessment. The aim of this study was to evaluate the correlation between MRI graft signal and postoperative functional scores, anterior knee laxity, and patient age at operation.

Anterior cruciate ligament (ACL) graft failure from rupture, attenuation, or malposition may cause recurrent subjective instability and objective laxity, and occurs in 3% to 22% of ACL reconstruction (ACLr) procedures. Revision ACLr is often indicated to restore knee stability, improve knee function, and facilitate return to cutting and pivoting activities. Prior to reconstruction, a thorough clinical and diagnostic evaluation is required to identify factors that may have predisposed an individual to recurrent ACL injury, appreciate concurrent intra-articular pathology, and select the optimal graft for revision reconstruction. Single-stage revision can be successful, although a staged approach may be used when optimal tunnel placement is not possible due to the position and/or widening of previous tunnels. Revision ACLr often involves concomitant procedures such as meniscal/chondral treatment, lateral extra-articular augmentation, and/or osteotomy. Although revision ACLr reliably restores knee stability and function, clinical outcomes and reoperation rates are worse than for primary ACLr. Cite this article: Bone Joint J 2023;105-B(5):474–480

Aims. To verify whether secretory leucocyte protease inhibitor (SLPI) can promote early tendon-to-bone healing after anterior cruciate ligament (ACL) reconstruction. Methods. In vitro: the mobility of the rat bone mesenchymal stem cells (BMSCs) treated with SLPI was evaluated by scratch assay. Then the expression levels of osteogenic differentiation-related genes were analyzed by real-time quantitative PCR (qPCR) to determine the osteogenic effect of SLPI on BMSCs. In vivo: a rat model of ACL reconstruction was used to verify the effect of SLPI on tendon-to-bone healing. All the animals of the SLPI group and the negative control (NC) group were euthanized for histological evaluation, micro-CT scanning, and biomechanical testing. Results. SLPI improved the migration ability of BMSCs and upregulated the expression of genes related to osteogenic differentiation of BMSCs in vitro. In vivo, the SLPI group had higher histological scores at the tendon-bone interface by histological evaluation. Micro-CT showed more new bone formation and bone ingrowth around the grafted tendon in the SLPI group. Evaluation of the healing strength of the tendon-bone connection showed that the SLPI group had a higher maximum failure force and stiffness. Conclusion. SLPI can effectively promote early tendon-to-bone healing after ACL reconstruction via enhancing the migration and osteogenic differentiation of BMSCs. Cite this article: Bone Joint Res 2022;11(7):503–512

Aims. The effects of remnant preservation on the anterior cruciate ligament (ACL) and its relationship with the tendon graft remain unclear. We hypothesized that the co-culture of remnant cells and bone marrow stromal cells (BMSCs) decreases apoptosis and enhances the activity of the hamstring tendons and tenocytes, thus aiding ACL reconstruction. Methods. The ACL remnant, bone marrow, and hamstring tendons were surgically harvested from rabbits. The apoptosis rate, cell proliferation, and expression of types I and III collagen, transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), and tenogenic genes (scleraxis (SCX), tenascin C (TNC), and tenomodulin (TNMD)) of the hamstring tendons were compared between the co-culture medium (ACL remnant cells (ACLRCs) and BMSCs co-culture) and control medium (BMSCs-only culture). We also evaluated the apoptosis, cell proliferation, migration, and gene expression of hamstring tenocytes with exposure to co-culture and control media. Results. Compared to BMSCs-only culture medium, the co-culture medium showed substantially decreased early and late apoptosis rates, attenuation of intrinsic and extrinsic apoptotic pathways, and enhanced proliferation of the hamstring tendons and tenocytes. In addition, the expression of collagen synthesis, TGF-β, VEGF, and tenogenic genes in the hamstring tendons and tenocytes significantly increased in the co-culture medium compared to that in the control medium. Conclusion. In the presence of ACLRCs and BMSCs, the hamstring tendons and tenocytes significantly attenuated apoptosis and enhanced the expression of collagen synthesis, TGF-β, VEGF, and tenogenic genes. This in vitro study suggests that the ACLRCs mixed with BMSCs could aid regeneration of the hamstring tendon graft during ACL reconstruction. Cite this article: Bone Joint Res 2023;12(1):9–21

Anterior cruciate ligament (ACL) injuries have been increasing, especially amongst adolescents. These injuries can increase the risk for early-onset knee osteoarthritis (OA). The consequences of late-stage knee OA include structural joint change, functional limitations and persistent pain. Interleukin-6 (IL-6) is a pro-inflammatory biomarker reflecting knee joint healing, and increasing evidence suggests that IL-6 may play a critical role in the development of pathological pain. The purpose of this study was to determine the relationship between subjective knee joint pain and function, and synovial fluid concentrations of the pro-inflammatory cytokine IL-6, in adolescents undergoing anterior cruciate ligament reconstruction surgery. Seven youth (12-17 yrs.) undergoing anterior cruciate ligament (ACL) reconstruction surgery participated in this study. They completed the Pedi International Knee Documentation Committee (Pedi-IKDC) questionnaire on knee joint pain and function. At the time of their ACL reconstruction surgery, synovial fluid samples were collected through aspiration to dryness with a syringe without saline flushing. IL-6 levels in synovial fluid (sf) were measured using enzyme linked immunosorbent assay. Spearman's rho correlation coefficient was used to determine the correlation between IL-6 levels and scores from the Pedi-IKDC questionnaire. There was a statistically significant correlation between sfIL-6 levels and the Pedi-IKDC Symptoms score (-.929, p=0.003). The correlations between sfIL-6 and Pedi-IKDC activity score (.546, p = .234) and between sfIL-6 and total Pedi-IKDC score (-.536, p = .215) were not statistically significant. This is the first study to evaluate IL-6 as a biomarker of knee joint healing in an adolescent population, reported a very strong correlation (-.929, p=0.003) between IL-6 in knee joint synovial fluid and a subjective questionnaire on knee joint pain. These findings provide preliminary scientific evidence regarding the relationship between knee joint pain, as determined by a validated questionnaire and the inflammatory and healing status of the patient's knee. This study provides a basis and justification for future longitudinal research on biomarkers of knee joint healing in patients throughout their recovery and rehabilitation process. Incorporating physiological and psychosocial variables to current return-to-activity (RTA) criteria has the potential to improve decision making for adolescents following ACL reconstruction to reduce premature RTA thereby reducing the risk of re-injury and risk of early-onset knee OA in adolescents

The anterior cruciate ligament (ACL) is frequently injured in elite athletes, with females up to eight times more likely to suffer an ACL tear than males. Biomechanical and hormonal factors have been thoroughly investigated; however, there remain unknown factors that need investigation. The mechanism of injury differs between males and females, and anatomical differences contribute significantly to the increased risk in females. Hormonal factors, both endogenous and exogenous, play a role in ACL laxity and may modify the risk of injury. However, data are still limited, and research involving oral contraceptives is potentially associated with methodological and ethical problems. Such characteristics can also influence the outcome after ACL reconstruction, with higher failure rates in females linked to a smaller diameter of the graft, especially in athletes aged < 21 years. The addition of a lateral extra-articular tenodesis can improve the outcomes after ACL reconstruction and reduce the risk of failure, and it should be routinely considered in young elite athletes. Sex-specific environmental differences can also contribute to the increased risk of injury, with more limited access to and availablility of advanced training facilities for female athletes. In addition, football kits are designed for male players, and increased attention should be focused on improving the quality of pitches, as female leagues usually play the day after male leagues. The kit, including boots, the length of studs, and the footballs themselves, should be tailored to the needs and body shapes of female athletes. Specific physiotherapy programmes and training protocols have yielded remarkable results in reducing the risk of injury, and these should be extended to school-age athletes. Finally, psychological factors should not be overlooked, with females’ greater fear of re-injury and lack of confidence in their knee compromising their return to sport after ACL injury. Both intrinsic and extrinsic factors should be recognized and addressed to optimize the training programmes which are designed to prevent injury, and improve our understanding of these injuries. Cite this article: Bone Joint J 2023;105-B(10):1033–1037

Anterior cruciate ligament (ACL) injuries are among the most common and debilitating knee injuries in professional athletes with an incidence in females up to eight-times higher than their male counterparts. ACL injuries can be career-threatening and are associated with increased risk of developing knee osteoarthritis in future life. The increased risk of ACL injury in females has been attributed to various anatomical, developmental, neuromuscular, and hormonal factors. Anatomical and hormonal factors have been identified and investigated as significant contributors including osseous anatomy, ligament laxity, and hamstring muscular recruitment. Postural stability and impact absorption are associated with the stabilizing effort and stress on the ACL during sport activity, increasing the risk of noncontact pivot injury. Female patients have smaller diameter hamstring autografts than males, which may predispose to increased risk of re-rupture following ACL reconstruction and to an increased risk of chondral and meniscal injuries. The addition of an extra-articular tenodesis can reduce the risk of failure; therefore, it should routinely be considered in young elite athletes. Prevention programs target key aspects of training including plyometrics, strengthening, balance, endurance and stability, and neuromuscular training, reducing the risk of ACL injuries in female athletes by up to 90%. Sex disparities in access to training facilities may also play an important role in the risk of ACL injuries between males and females. Similarly, football boots, pitches quality, and football size and weight should be considered and tailored around females’ characteristics. Finally, high levels of personal and sport-related stress have been shown to increase the risk of ACL injury which may be related to alterations in attention and coordination, together with increased muscular tension, and compromise the return to sport after ACL injury. Further investigations are still necessary to better understand and address the risk factors involved in ACL injuries in female athletes. Cite this article: Bone Jt Open 2024;5(2):94–100

Aims. The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA). Methods. Two experimentally validated finite element models of tibia were implanted with UKA-M, Bi-UKA, and BCR-TKA. Intraoperative loads were applied through the condyles, anterior cruciate ligament (ACL), medial collateral ligament (MCL), and lateral collateral ligament (LCL), and the risk of fracture (ROF) was evaluated in the spine as the ratio of the 95. th. percentile maximum principal elastic strains over the tensile yield strain of proximal tibial bone. Results. Peak tensile strains occurred on the anterior portion of the medial sagittal cut in all simulations. Lateral translation of the medial implant in Bi-UKA had the largest increase in ROF of any of the implant positions (43%). Overstuffing the joint by 2 mm had a much larger effect, resulting in a six-fold increase in ROF. Bi-UKA had ~10% increased ROF compared to UKA-M for both the male and female models, although the smaller, less dense female model had a 1.4 times greater ROF compared to the male model. Removal of anterior bone akin to BCR-TKA doubled ROF compared to Bi-UKA. Conclusion. Tibial eminence avulsion fracture has a similar risk associated with Bi-UKA to UKA-M. The risk is higher for smaller and less dense tibiae. To minimize risk, it is most important to avoid overstuffing the joint, followed by correctly positioning the medial implant, taking care not to narrow the bone island anteriorly. Cite this article: Bone Joint Res 2022;11(8):575–584

Aims. The aim of this study was to compare the preinjury functional scores with the postinjury preoperative score and postoperative outcome scores following anterior cruciate ligament (ACL) reconstruction surgery (ACLR). Methods. We performed a prospective study on patients who underwent primary ACLR by a single surgeon at a single centre between October 2010 and January 2018. Preoperative preinjury scores were collected at time of first assessment after the index injury. Preoperative (pre- and post-injury), one-year, and two-year postoperative functional outcomes were assessed by using the Knee injury and Osteoarthritis Outcome Score (KOOS), Lysholm Knee Score, and Tegner Activity Scale. Results. We enrolled 308 males and 263 females of mean age 27 years (19 to 46). The mean preinjury and preoperative post-injury Lysholm Knee Scores were 94 (73 to 100) and 63 (25 to 85), respectively, while the respective mean scores at one and two years postoperatively were 84 (71 to 100) and 89 (71 to 100; p < 0.001). The mean Tegner preinjury and preoperative post-injury scores were 7 (3 to 9) and 3 (0 to 6), respectively, while the respective mean scores at one and two years postoperatively were 6 (1 to 8) and 6 (1 to 9) (p < 0.001). The mean KOOS scores at preinjury versus two years postoperatively were: symptoms (96 vs 84); pain (94 vs 87); activities of daily living (97 vs 91), sports and recreation function (84 vs 71), and quality of life (82 vs 69), respectively (p < 0.001). Conclusion. Functional scores improved following ACLR surgery at two years in comparison to preoperative post-injury scores. However, at two-year follow-up, the majority of patients failed to achieve their preinjury scores. The evaluation of ACLR outcomes needs to consider the preinjury scores rather than the immediate preoperative score that is usually collected. Cite this article: Bone Jt Open 2023;4(1):46–52

Aims. The aim of this study was to report the pooled prevalence of post-traumatic osteoarthritis (PTOA) and examine whether the risk of developing PTOA after anterior cruciate ligament (ACL) injury has decreased in recent decades. Methods. The PubMed and Web of Science databases were searched from 1 January 1980 to 11 May 2022. Patient series, observational studies, and clinical trials having reported the prevalence of radiologically confirmed PTOA after ACL injury, with at least a ten-year follow-up, were included. All studies were analyzed simultaneously, and separate analyses of the operative and nonoperative knees were performed. The prevalence of PTOA was calculated separately for each study, and pooled prevalence was reported with 95% confidence intervals (CIs) using either a fixed or random effects model. To examine the effect of the year of injury on the prevalence, a logit transformed meta-regression analysis was used with a maximum-likelihood estimator. Results from meta-regression analyses were reported with the unstandardized coefficient (β). Results. The pooled prevalence of PTOA was 37.9% (95% CI 32.1 to 44) for operatively treated ACL injuries with a median follow-up of 14.6 years (interquartile range (IQR) 10.6 to 16.7). For nonoperatively treated ACL injuries, the prevalence was 40.5% (95% CI 28.9 to 53.3), with a median of follow-up of 15 years (IQR 11.7 to 20.0). The association between the year of operation and the prevalence of PTOA was weak and imprecise and not related to the choice of treatment (operative β -0.038 (95% CI -0.076 to 0.000) and nonoperative β -0.011 (95% CI -0.101 to 0.079)). Conclusion. The initial injury, irrespective of management, has, by the balance of probability, resulted in PTOA within 20 years. In addition, the prevalence of PTOA has only slightly decreased during past decades. Therefore, further research is warranted to develop strategies to prevent the development of PTOA after ACL injuries. Cite this article: Bone Joint J 2023;105-B(11):1140–1148

Aims. Adenosine, lidocaine, and Mg. 2+. (ALM) therapy exerts differential immuno-inflammatory responses in males and females early after anterior cruciate ligament (ACL) reconstruction (ACLR). Our aim was to investigate sex-specific effects of ALM therapy on joint tissue repair and recovery 28 days after surgery. Methods. Male (n = 21) and female (n = 21) adult Sprague-Dawley rats were randomly divided into ALM or Saline control treatment groups. Three days after ACL rupture, animals underwent ACLR. An ALM or saline intravenous infusion was commenced prior to skin incision, and continued for one hour. An intra-articular bolus of ALM or saline was also administered prior to skin closure. Animals were monitored to 28 days, and joint function, pain, inflammatory markers, histopathology, and tissue repair markers were assessed. Results. Despite comparable knee function, ALM-treated males had reduced systemic inflammation, synovial fluid angiogenic and pro-inflammatory mediators, synovitis, and fat pad fibrotic changes, compared to controls. Within the ACL graft, ALM-treated males had increased expression of tissue repair markers, decreased inflammation, increased collagen organization, and improved graft-bone healing. In contrast to males, females had no evidence of persistent systemic inflammation. Compared to controls, ALM-treated females had improved knee extension, gait biomechanics, and elevated synovial macrophage inflammatory protein-1 alpha (MIP-1α). Within the ACL graft, ALM-treated females had decreased inflammation, increased collagen organization, and improved graft-bone healing. In articular cartilage of ALM-treated animals, matrix metalloproteinase (MMP)-13 expression was blunted in males, while in females repair markers were increased. Conclusion. At 28 days, ALM therapy reduces inflammation, augments tissue repair patterns, and improves joint function in a sex-specific manner. The study supports transition to human safety trials. Cite this article: Bone Joint Res 2024;13(6):279–293

Aims. A functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different posterior tibial slopes. Methods. ACL- or PCL-deficient models with posterior tibial slopes of 1°, 3°, 5°, 7°, and 9° were developed and compared to intact models. The kinematics and contact stresses on the tibiofemoral joint were evaluated under gait cycle loading conditions. Results. Anterior translation increased in ACL-deficient UKA cases compared with intact models. In contrast, posterior translation increased in PCL-deficient UKA cases compared with intact models. As the posterior tibial slope increased, anterior translation of ACL-deficient UKA increased significantly in the stance phase, and posterior translation of PCL-deficient UKA increased significantly in the swing phase. Furthermore, as the posterior tibial slope increased, contact stress on the other compartment increased in cruciate ligament-deficient UKAs compared with intact UKAs. Conclusion. Fixed-bearing medial UKA is a viable treatment option for patients with cruciate ligament deficiency, providing a less invasive procedure and allowing patient-specific kinematics to adjust posterior tibial slope. Patient selection is important, and while AP kinematics can be compensated for by posterior tibial slope adjustment, rotational stability is a prerequisite for this approach. ACL- or PCL-deficient UKA that adjusts the posterior tibial slope might be an alternative treatment option for a skilled surgeon. Cite this article: Bone Joint Res 2022;11(7):494–502

Aims. The aim of this study was to estimate the incremental use of resources, costs, and quality of life outcomes associated with surgical reconstruction compared to rehabilitation for long-standing anterior cruciate ligament (ACL) injury in the NHS, and to estimate its cost-effectiveness. Methods. A total of 316 patients were recruited and randomly assigned to either surgical reconstruction or rehabilitation (physiotherapy but with subsequent reconstruction permitted if instability persisted after treatment). Healthcare resource use and health-related quality of life data (EuroQol five-dimension five-level health questionnaire) were collected in the trial at six, 12, and 18 months using self-reported questionnaires and medical records. Using intention-to-treat analysis, differences in costs, and quality-adjusted life years (QALYs) between treatment arms were estimated adjusting for baseline differences and following multiple imputation of missing data. The incremental cost-effectiveness ratio (ICER) was estimated as the difference in costs divided by the difference in QALYs between reconstruction and rehabilitation. Results. At 18 months, patients in the surgical reconstruction arm reported higher QALYs (0.052 (95% confidence interval (CI) -0.012 to 0.117); p = 0.177) and higher NHS costs (£1,017 (95% CI 557 to 1,476); p < 0.001) compared to rehabilitation. This resulted in an ICER of £19,346 per QALY with the probability of surgical reconstruction being cost-effective of 51% and 72% at a willingness-to-pay threshold of £20,000 and £30,000 per QALY, respectively. Conclusion. Surgical reconstruction as a management strategy for patients with long-standing ACL injury is more effective, but more expensive, at 18 months compared to rehabilitation management. In the UK setting, surgical reconstruction is cost-effective. Cite this article: Bone Joint J 2024;106-B(1):38–45

Aims. Anterior cruciate ligament (ACL) rupture commonly leads to post-traumatic osteoarthritis, regardless of surgical reconstruction. This study uses standing MRI to investigate changes in contact area, contact centroid location, and tibiofemoral alignment between ACL-injured knees and healthy controls, to examine the effect of ACL reconstruction on these parameters. Methods. An upright, open MRI was used to directly measure tibiofemoral contact area, centroid location, and alignment in 18 individuals with unilateral ACL rupture within the last five years. Eight participants had been treated nonoperatively and ten had ACL reconstruction performed within one year of injury. All participants were high-functioning and had returned to sport or recreational activities. Healthy contralateral knees served as controls. Participants were imaged in a standing posture with knees fully extended. Results. Participants’ mean age was 28.4 years (SD 7.3), the mean time since injury was 2.7 years (SD 1.6), and the mean International Knee Documentation Subjective Knee Form score was 84.4 (SD 13.5). ACL injury was associated with a 10% increase (p = 0.001) in contact area, controlling for compartment, sex, posture, age, body mass, and time since injury. ACL injury was associated with a 5.2% more posteriorly translated medial centroid (p = 0.001), equivalent to a 2.6 mm posterior translation on a representative tibia with mean posteroanterior width of 49.4 mm. Relative to the femur, the tibiae of ACL ruptured knees were 2.3 mm more anteriorly translated (p = 0.003) and 2.6° less externally rotated (p = 0.010) than healthy controls. ACL reconstruction was not associated with an improvement in any measure. Conclusion. ACL rupture was associated with an increased contact area, posteriorly translated medial centroid, anterior tibial translation, and reduced tibial external rotation in full extension. These changes were present 2.7 years post-injury regardless of ACL reconstruction status. Cite this article: Bone Joint J 2021;103-B(9):1505–1513

Aims. The aim of this study was to evaluate the association between chondral injury and interval from anterior cruciate ligament (ACL) tear to surgical reconstruction (ACLr). Methods. Between January 2012 and January 2022, 1,840 consecutive ACLrs were performed and included in a single-centre retrospective cohort. Exclusion criteria were partial tears, multiligament knee injuries, prior ipsilateral knee surgery, concomitant unicompartmental knee arthroplasty or high tibial osteotomy, ACL agenesis, and unknown date of tear. A total of 1,317 patients were included in the final analysis, with a median age of 29 years (interquartile range (IQR) 23 to 38). The median preoperative Tegner Activity Score (TAS) was 6 (IQR 6 to 7). Patients were categorized into four groups according to the delay to ACLr: < three months (427; 32%), three to six months (388; 29%), > six to 12 months (248; 19%), and > 12 months (254; 19%). Chondral injury was assessed during arthroscopy using the International Cartilage Regeneration and Joint Preservation Society classification, and its association with delay to ACLr was analyzed using multivariable analysis. Results. In the medial compartment, delaying ACLr for more than 12 months was associated with an increased rate (odds ratio (OR) 1.93 (95% confidence interval (CI) 1.27 to 2.95); p = 0.002) and severity (OR 1.23 (95% CI 1.08 to 1.40); p = 0.002) of chondral injuries, compared with < three months, with no association in patients aged > 50 years old. No association was found for shorter delays, but the overall dose-effect analysis was significant for the rate (p = 0.015) and severity (p = 0.026) of medial chondral injuries. Increased TAS was associated with a significantly reduced rate (OR 0.88 (95% CI 0.78 to 0.99); p = 0.036) and severity (OR 0.96 (95% CI 0.92 to 0.99); p = 0.017) of medial chondral injuries. In the lateral compartment, no association was found between delay and chondral injuries. Conclusion. Delay was associated with an increased rate and severity of medial chondral injuries in a dose-effect fashion, in particular for delays > 12 months. Younger patients seem to be at higher risk of chondral injury when delaying surgery. The timing of ACLr should be optimally reduced in this population. Cite this article: Bone Joint J 2023;105-B(9):953–960

Aims. Proliferation, migration, and differentiation of anterior cruciate ligament (ACL) remnant and surrounding cells are fundamental processes for ACL reconstruction; however, the interaction between ACL remnant and surrounding cells is unclear. We hypothesized that ACL remnant cells preserve the capability to regulate the surrounding cells’ activity, collagen gene expression, and tenogenic differentiation. Moreover, extracorporeal shock wave (ESW) would not only promote activity of ACL remnant cells, but also enhance their paracrine regulation of surrounding cells. Methods. Cell viability, proliferation, migration, and expression levels of Collagen-I (COL-I) A1, transforming growth factor beta (TGF-β), and vascular endothelial growth factor (VEGF) were compared between ACL remnant cells untreated and treated with ESW (0.15 mJ/mm. 2. , 1,000 impulses, 4 Hz). To evaluate the subsequent effects on the surrounding cells, bone marrow stromal cells (BMSCs)’ viability, proliferation, migration, and levels of Type I Collagen, Type III Collagen, and tenogenic gene (Scx, TNC) expression were investigated using coculture system. Results. ESW-treated ACL remnant cells presented higher cell viability, proliferation, migration, and increased expression of COL-I A1, TGF-β, and VEGF. BMSC proliferation and migration rate significantly increased after coculture with ACL remnant cells with and without ESW stimulation compared to the BMSCs alone group. Furthermore, ESW significantly enhanced ACL remnant cells’ capability to upregulate the collagen gene expression and tenogenic differentiation of BMSCs, without affecting cell viability, TGF-β, and VEGF expression. Conclusion. ACL remnant cells modulated activity and differentiation of surrounding cells. The results indicated that ESW enhanced ACL remnant cells viability, proliferation, migration, and expression of collagen, TGF-β, VEGF, and paracrine regulation of BMSC proliferation, migration, collagen expression, and tenogenesis. Cite this article: Bone Joint Res 2020;9(8):457–467

Objectives. The aim of this study was to investigate the biomechanical effect of the anterolateral ligament (ALL), anterior cruciate ligament (ACL), or both ALL and ACL on kinematics under dynamic loading conditions using dynamic simulation subject-specific knee models. Methods. Five subject-specific musculoskeletal models were validated with computationally predicted muscle activation, electromyography data, and previous experimental data to analyze effects of the ALL and ACL on knee kinematics under gait and squat loading conditions. Results. Anterior translation (AT) significantly increased with deficiency of the ACL, ALL, or both structures under gait cycle loading. Internal rotation (IR) significantly increased with deficiency of both the ACL and ALL under gait and squat loading conditions. However, the deficiency of ALL was not significant in the increase of AT, but it was significant in the increase of IR under the squat loading condition. Conclusion. The results of this study confirm that the ALL is an important lateral knee structure for knee joint stability. The ALL is a secondary stabilizer relative to the ACL under simulated gait and squat loading conditions. Cite this article: Bone Joint Res 2019;8:509–517

Aims. The aim of this prospective study was to assess the long-term clinical, radiological, functional, and quality of life (QoL)-related outcome of patients treated with the synthetic Ligament Advanced Reinforcement System (LARS) device for anterior cruciate ligament (ACL) rupture. Methods. A total of 41 patients who underwent ACL reconstruction with the LARS device (mean age 39.8 years (SD 12.1 ); 32% females (n = 13)) were prospectively included between August 2001 and March 2005. MRI scans and radiographs were performed at a median follow-up of 2.0 years (interquartile range (IQR) 1.3 to 3.0; n = 40) and 12.8 years (IQR 12.1 to 13.8; n = 22). Functional and QoL-related outcome was assessed in 29 patients at a median follow-up of 12.8 years (IQR 12.0 to 14.0) and clinically reconfirmed at latest median follow-up of 16.5 years (IQR 15.5 to 17.9). International Knee Documentation Committee (IKDC) and Tegner scores were obtained pre- and postoperatively, and Lysholm score postoperatively only. At latest follow-up, range of motion, knee stability tests, 36-Item Short Form Health Survey (SF-36), and IKDC scores were ascertained. Complications and reoperations during follow-up were documented. Results. Cumulative complication rate was 66% (n = 27), with 11 developing within one year from surgery and 16 after one year (including five patients with both early and late complications). Ten graft failures (24%) and eight cases of reactive synovitis were observed (20%). All 11 patients with early complications and ten with late complications underwent reoperation (including five with another surgical procedure for early complications), amounting to a cumulative reoperation rate of 51% (n = 21). Revision ACL reconstruction was performed in one patient (2.4%). Median IKDC at latest follow-up was 89.7 (IQR 78.2 to 93.1), being significantly worse in the event of previous complications. Lachman test was positive in 56% (n = 15) of reconstructed knees. All norm-based SF-36 items were at or above median at latest follow-up, and did not differ depending on development of complications. Conclusion. Despite good functional and QoL-related results in the long term, the cumulative complication rate of 66%, including graft failures and reactive synovitis, has to be viewed with great concern. Cite this article: Bone Joint J 2022;104-B(2):242–248

Aims. To evaluate graft healing of decellularized porcine superflexor tendon (pSFT) xenograft in an ovine anterior cruciate ligament (ACL) reconstruction model using two femoral fixation devices. Also, to determine if pSFT allows functional recovery of gait as compared with the preoperative measurements. Methods. A total of 12 sheep underwent unilateral single-bundle ACL reconstruction using pSFT. Two femoral fixation devices were investigated: Group 1 (n = 6) used cortical suspensory fixation (Endobutton CL) and Group 2 (n = 6) used cross-pin fixation (Stratis ST). A soft screw was used for tibial fixation. Functional recovery was quantified using force plate analysis at weeks 5, 8, and 11. The sheep were euthanized after 12 weeks and comprehensive histological analysis characterized graft healing at the graft-bone interface and the intra-articular graft (ligamentization). Results. The pSFT remodelled into a ligament-like structure and no adverse inflammatory reaction was seen. The ground reaction force in the operated leg of the Endobutton group was higher at 11 weeks (p < 0.05). An indirect insertion was seen at the graft-bone interface characterized by Sharpey-like fibres. Qualitative differences in tendon remodelling were seen between the two groups, with greater crimp-like organization and more aligned collagen fibres seen with Endobutton fixation. One graft rupture occurred in the cross-pin group, which histologically showed low collagen organization. Conclusion. Decellularized pSFT xenograft remodels into a ligament-like structure after 12 weeks and regenerates an indirect-type insertion with Sharpey-like fibres. No adverse inflammatory reaction was observed. Cortical suspensory femoral fixation was associated with more enhanced graft remodelling and earlier functional recovery when compared with the stiffer cross-pin fixation

Aims. This study aims to determine the proportion of patients with end-stage knee osteoarthritis (OA) possibly suitable for partial (PKA) or combined partial knee arthroplasty (CPKA) according to patterns of full-thickness cartilage loss and anterior cruciate ligament (ACL) status. Methods. A cross-sectional analysis of 300 consecutive patients (mean age 69 years (SD 9.5, 44 to 91), mean body mass index (BMI) 30.6 (SD 5.5, 20 to 53), 178 female (59.3%)) undergoing total knee arthroplasty (TKA) for Kellgren-Lawrence grade ≥ 3 knee OA was conducted. The point of maximal tibial bone loss on preoperative lateral radiographs was determined as a percentage of the tibial diameter. At surgery, Lachman’s test and ACL status were recorded. The presence of full-thickness cartilage loss within 16 articular surface regions (two patella, eight femoral, six tibial) was recorded. Results. According to articular cartilage loss and ACL status, 195/293 (67%) were suitable for PKA or CPKA: medial unicompartmental knee arthroplasty (UKA) 97/293 (33%); lateral UKA 25 (9%); medial bicompartmental arthroplasty 31 (11%); lateral bicompartmental arthroplasty 12 (4%); bicondylar-UKA 23 (8%); and patellofemoral arthroplasty (PFA) seven (2%). The ACL was intact in 166 (55%), frayed in 82 (27%), disrupted in 12 (4%), and absent in 33 (11%). Lachman testing was specific (97%) but poorly sensitive (38%) for disrupted/absent ACLs. The point of maximal tibial bone loss showed good interclass correlation (ICC 0.797, 0.73 to 0.85 95% confidence interval (CI); p < 0.001) and was more posterior when the ACL was absent. Maximum tibial bone loss occurring at > 55% of the anterior to posterior distance predicted ACL absence with 93% sensitivity and 91% specificity (area under the curve 0.97 (0.94 to 0.99 95% CI; p < 0.001). Conclusion. ACL status can be reliably determined from a lateral radiograph using the location of maximal tibial bone loss. According to regions of cartilage loss and ACL status, two-thirds of patients with end-stage knee OA could potentially be treated with PKA or CPKA. Cite this article: Bone Joint J 2020;102-B(6):716–726

Aims. The aim of this study was to screen the entire genome for genetic markers associated with risk for anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injury. Methods. Genome-wide association (GWA) analyses were performed using data from the Kaiser Permanente Research Board (KPRB) and the UK Biobank. ACL and PCL injury cases were identified based on electronic health records from KPRB and the UK Biobank. GWA analyses from both cohorts were tested for ACL and PCL injury using a logistic regression model adjusting for sex, height, weight, age at enrolment, and race/ethnicity using allele counts for single nucleotide polymorphisms (SNPs). The data from the two GWA studies were combined in a meta-analysis. Candidate genes previously reported to show an association with ACL injury in athletes were also tested for association from the meta-analysis data from the KPRB and the UK Biobank GWA studies. Results. There was a total of 2,214 cases of ACL and PCL injury and 519,869 controls within the two cohorts, with three loci demonstrating a genome-wide significant association in the meta-analysis: INHBA, AEBP2, and LOC101927869. Of the eight candidate genes previously studied in the literature, six were present in the current dataset, and only COL3A1 (rs1800255) showed a significant association (p = 0.006). Conclusion. Genetic markers in three novel loci in this study and one previously-studied candidate gene were identified as potential risk factors for ACL and PCL injury and deserve further validation and investigation of molecular mechanisms. Cite this article: Bone Jt Open 2021;2(6):414–421

A method is proposed to assess risk parameters of anterior cruciate ligament (ACL) injury using human pose estimation (HPE) and a single stereo depth camera. Detectron2 is used to identify key points of a subject performing a single leg jump test. This allows dynamic pivot of the knee to be assessed during landing using four risk parameters: knee valgus, knee translation in the coronal plane, pelvic tilt, and head-ankle alignment (body sway). Results show the model has an accuracy of 7° in angular measurements and 38 mm in linear measurements. Compared to previous studies, which only consider front-on analysis, this method has partially reduced accuracy in linear measurements and half the accuracy in angular measurements. Despite this, coupling information from multiple risk parameters reduces the accuracy required on any one parameter and the use of a single depth camera enables reliable analysis at a subject orientation of ±45° relative to the camera. These factors create a novel solution, proposing the ability for broad evaluation of ACL risk parameters in environments outside a testing laboratory, which has not been done before

Aims. The objectives of this study were to assess the effect of anterior cruciate ligament (ACL) resection on flexion-extension gaps, mediolateral soft tissue laxity, maximum knee extension, and limb alignment during primary total knee arthroplasty (TKA). Methods. This prospective study included 140 patients with symptomatic knee osteoarthritis undergoing primary robotic-arm assisted TKA. All operative procedures were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess study outcomes pre- and post-ACL resection with knee extension and 90° knee flexion. This study included 76 males (54.3%) and 64 females (45.7%) with a mean age of 64.1 years (SD 6.8) at time of surgery. Mean preoperative hip-knee-ankle deformity was 6.1° varus (SD 4.6° varus). Results. ACL resection increased the mean extension gap significantly more than the flexion gap in the medial (mean 1.2 mm (SD 1.0) versus mean 0.2 mm (SD 0.7) respectively; p < 0.001) and lateral (mean 1.1 mm (SD 0.9) versus mean 0.2 mm (SD 0.6) respectively; p < 0.001) compartments. The mean gap differences following ACL resection did not create any significant mediolateral soft tissue laxity in extension (gap difference: mean 0.1 mm (SD 2.4); p = 0.89) or flexion (gap difference: mean 0.2 mm (SD 3.1); p = 0.40). ACL resection did not significantly affect maximum knee extension (change in maximum knee extension = mean 0.2° (SD 0.7°); p = 0.23) or fixed flexion deformity (mean 4.2° (SD 3.2°) pre-ACL release versus mean 3.9° (SD 3.7°) post-ACL release; p = 0.61). ACL resection did not significantly affect overall limb alignment (change in alignment = mean 0.2° valgus (SD 1.0° valgus; p = 0.11). Conclusion. ACL resection creates flexion-extension mismatch by increasing the extension gap more than the flexion gap. However, gap differences following ACL resection do not create any mediolateral soft tissue laxity in extension or flexion. ACL resection does not affect maximum knee extension or overall limb alignment. Cite this article: Bone Joint J 2020;102-B(4):442–448

Abstract. Background. Anterior cruciate ligament (ACL) injuries with coinciding posterolateral tibial plateau (PLTP) depression fractures are rare. According to the most up to date literature, addressing the PLTP is crucial in preventing failure of the ACL. However, the surgical management of these injuries pose a great challenge to orthopaedic surgeons, given the anatomical location of the depressed PTP fragment. We report a case of a 17-year-old patient presenting to our department with this injury and describe a novel fixation method, that has not been described in the literature. Surgical Technique. A standard 2-portal arthroscopy is used to visualise the fractures. The PLTP is addressed first. With the combined use of arthroscopy and fluoroscopy, a guide pin is triangulated from the anteromedial aspect of the tibia, towards the depressed plateau fragment. Once the guide pin is approximately 1cm from the centre of the fragment, it is over-drilled with a cannulated drill, and simultaneously bluntly punched up to its original anatomical location. Bone graft is then used to fill the void, supported by two subchondral screws. Both fluoroscopy and arthroscopy are used to confirm adequacy of fixation. Finally, the tibial spine avulsion fracture is repaired arthroscopically using the standard suture bridging technique. Conclusion. We describe a novel, one-stage, minimally invasive approach that addresses both the ACL injury and PLTP fracture. We highlight the advantages of utilising this approach and functional outcomes

The anterior cruciate ligament (ACL) is the connective tissue located at the end of long bones providing stability to the knee joint. After tear or rupture clinical reconstruction of the tissue remains a challenge due to the particular mechanical properties required for proper functioning of the tissue. The outstanding mechanical properties of the ACL are characterized by a viscoelastic behavior responsible of the dissipation of the loads that are transmitted to the bone. These mechanical properties are the result of a very specialized graded extracellular matrix that transitions smoothly between the heterotypic cells, stiffness and composition of the ACL and the adjacent bone. Thus, mimicking the zonal biochemical composition, cellular phenotype and organization are key to reset the proper functioning of the ACL. We have previously shown how the biochemical composition presented to cells in electrospun scaffolds results in haptokinesis, reverting contact-guidance effects. [1]. Here, we demonstrate that contact guidance can also be disrupted by structural parameters in aligned wavy scaffolds. The presentation of a wavy fiber arrangement affected the cell organization and the deposition of a specific ECM characteristic of fibrocartilage. Cells cultured in wavy scaffolds grew in aggregates, deposited an abundant ECM rich in fibronectin and collagen II, and expressed higher amounts of collagen II, X and tenomodulin as compared to aligned scaffolds. In-vivo implantation in rabbits of triphasic scaffolds accounting for aligned-wavy-aligned zones showed a high cellular infiltration and the formation of an oriented ECM, as compared to traditional aligned scaffolds. [2]

The Pivot-shift test is a clinical test for knee instability for patinets with Anterior cruciate ligament (ACL), however the test has low inter-observer reliability. Dynamic radiostereometry (dRSA) imaging is a highly precise method for objective evaluation of joint kinematics. The purpose of the study was to quantify precise knee kinematics during Pivot-shift test by use of the non-invasive dynamic RSA imaging. Eight human donor legs with hemipelvis were evaluated. Ligament lesion intervention of the ACL was performed during arthroscopy and anterolateral ligament (ALL) section was performed as a capsular incision. Pivot-shift test examination was recorded with dRSA on ligament intact knees, ACL-deficient knees and ACL+ALL-deficient knees. A Pivot-shift pattern was identifyable after ligament lesion as a change in tibial posterior drawer velocity from 7.8 mm/s in ligament intact knees, to 30.4 mm/s after ACL lesion, to 35.1 mm/s after combined ACL-ALL lesion. The anterior-posterior drawer excursion increased from 2.8 mm in ligament intact knees, to 7.2 mm after ACL lesion, to 7.6 mm after combined lesion. Furthermore a change in tibial rotation was found, with increasing external rotation at the end of the pivot-shift motion going from intact to ACL+ALL-deficient knees. This experimental study demonstrates the feasibility of RSA to objectively quantify the kinematic instability patterns of the knee during the Pivot-shift test. The dynamic parameters found through RSA displayed the kinematic changes from ACL to combined ACL-ALL ligament lesion

Introduction. Anterior cruciate ligament (ACL) injuries represent a significant burden of disease to the orthopaedic surgeon and often necessitate surgical reconstruction in the presence of instability. The hamstring graft has traditionally been used to reconstruct the ACL but the quadriceps tendon (QT) graft has gained popularity due to its relatively low donor site morbidity. Methods. This is a single centre comparative retrospective analysis of prospectively collected data of patients who had an ACL reconstruction (either with single tendon quadrupled hamstring graft or soft tissue quadriceps tendon graft). All surgeries were performed by a single surgeon using the All-inside technique. For this study, there were 20 patients in each group. All patients received the same post-operative rehabilitation protocol and were added to the National Ligament Registry to monitor their patient related outcome scores (PROM). Results. The average age of patients in the QT group was 29 years (16 males, 4 females) and in the hamstring group was 28 years (18 males, 2 females). The most common mechanism of injury in both groups was a contact twisting injury. There were no statistical differences between the two patient groups in regards to PROMS and need for further revision surgery as analysed on the National Ligament Registry. Conclusions. The all soft tissue QT graft seems to be equivocal to quadrupled hamstring graft in terms of patient function and recovery graft characteristics. Further research may be needed to elucidate the long-term results of the all soft tissue QT graft given its recent increase in use

Abstract. Purpose. Since arthroscopic reconstruction of the anterior cruciate ligament (ACL) started, the use of peroneus longus grafts for primary ACL reconstruction (ACLR) was never thought of as there is very scant literature on it. So, our study aims to compare the functional outcome and complications in patients with ACL injury managed by ACLR with peroneus longus tendon (PLT) and hamstring tendons (HT) respectively. Materials and Methods. Patients with 16–50 years of either gender presenting with symptomatic ACL deficiency were admitted for arthroscopic single bundle ACLR and allocated into two groups (PLT and HT) operated and observed. Functional scores (IKDC and Lysholm score), clinical knee evaluation, donor site morbidity (AOFAS score) and thigh circumference were recorded preoperatively and at six months, one year post-operatively. The same post-op rehabilitation protocol was followed in both groups. Results. 194 patients (hamstring n=96, peroneus n=98) met the inclusion criteria. There were no significant differences between the pre-op, six months post-op and one-year postoperative score between the hamstring and peroneus longus groups in the IKDC (p=0.356) and Lysholm knee score (p=0.289). The mean for the AOFAS was 99.05±3.56 and 99.80±0.70 in the PLT and HT group respectively showing no statistical difference, with a significant improvement in thigh muscle wasting among the PLT group at final follow-up (p<0.001). Conclusion. We observed similar knee stability, functional outcome and no obvious donor site morbidity among both groups and recommend that a PL graft may be a safe, effective, and viable option for arthroscopic single bundle ACL reconstruction

Despite extensive research aimed at improving surgical outcomes of enthesis injuries, re-tears remain a common problem, as the repairs often lead to fibrovascular scar as opposed to a zonal enthesis. Zonal enthesis formation involves anchoring collagen fibers, synthesizing proteoglycan-rich fibrocartilage, and mineralizing this fibrocartilage [1]. During development, the hedgehog signaling pathway promotes the formation and maturation of fibrocartilage within the zonal tendon-to-bone enthesis [1-4]. However, whether this pathway has a similar role in adult zonal tendon-to-bone repair is not known. Therefore, we developed a murine anterior cruciate ligament (ACL) reconstruction model [5] to better understand the zonal tendon-to-bone repair process and perturb key developmental regulators to determine the extent to which they can promote successful repair in the adult. In doing so, we activated the hedgehog signaling pathway both genetically using transgenic mice and pharmacologically via agonist injections. We demonstrated that both treatments improved the formation of zonal attachments and tunnel integration strength [6]. These improved outcomes were due in part to hedgehog signaling's positive role in proliferation of the bone marrow stromal cell (bMSC) progenitor pool and subsequent fibrocartilage production of bMSC progeny cells that form the attachments. These results suggest that, similar to growth and development, hedgehog signaling promotes the production and maturation of fibrocartilage during tendon-to-bone integration in adults. Lastly, we developed localized drug delivery systems to further improve the treatment of these debilitating injuries in future translational studies. Acknowledgements: This work was supported by NIH R01AR076381, R21AR078429, R00AR067283, F31AR079840, T32AR007132, and P30AR069619, in addition to the McCabe Fund Pilot Award at the University of Pennsylvania

The bone-patellar tendon-bone (BTB) autograft has a lower rate of graft failure but a higher rate of contralateral anterior cruciate ligament (ACL) injury after primary ACL reconstruction. Subsequent contralateral injury may be a marker of success of the BTB graft, but it is unclear whether the type of graft influences the rate of return to sport. This study aimed to compare the rates of return to weekly sport and return to preinjury activity levels between the BTB and hamstring tendon autografts following primary ACL reconstruction. Prospective data on primary ACL reconstructions recorded in the New Zealand ACL Registry between April 2014-November 2019 were analyzed. The primary outcome was return to weekly sport, defined as a Marx activity score of 8, at 2-year follow-up. The secondary outcome was return to preinjury activity level, defined as a post-operative Marx activity score that was equal or greater to the patient's preinjury Marx score. Return to sport was compared between the BTB and hamstring tendon autografts via multivariate binary logistic regression with adjustment for patient demographics. 4259 patients were analyzed, of which 50.3% were playing weekly sport (n = 2144) and 28.4% had returned to their preinjury activity level (n = 1211) at 2-year follow-up. A higher rate of return to weekly sport was observed with the BTB autograft compared to the hamstring tendon autograft (58.7% versus 47.9%, adjusted odds ratio = 1.23, p = 0.009). Furthermore, the BTB autograft had a higher rate of return to preinjury activity levels (31.5% versus 27.5%, adjusted odds ratio = 1.21, p = 0.025). The BTB autograft is associated with a higher return to sport and may explain the higher rate of contralateral ACL injury following primary ACL reconstruction

To address the current challenge of anterior cruciate ligament (ACL) reconstruction, this study is the first to fabricate a braided collagen rope (BCR) which mimics native hamstring for ACL reconstruction. The study aims to evaluate the biological and biomechanical properties of BCR both in vivo and vitro. Rabbit ACL reconstruction model using collagen rope and autograft (hamstring tendon) was conducted. The histological and biomechanical evaluations were conducted at 6-, 12-, 18, 26-week post-operation. In vitro study included cell morphology analysis, cell function evaluation and RNA sequencing of the tenocytes cultured on BCR. A cadaver study was also conducted to verify the feasibility of BCR for ACL reconstruction. BCR displays satisfactory mechanical strength similar to hamstring graft for ACL reconstruction in rabbit. Histological assessment showed BCR restore ACL morphology at 26 weeks similar to native ACL. The superior dynamic ligamentization in BCR over autograft group was evidenced by assessment of cell and collagen morphology and orientation. The in vitro study showed that the natural collagen fibres within BCR enables to signal the morphology adaptation and orientation of human tenocytes in bioreactor. BCR enables to enhance cell proliferation and tenogenic expression of tenocytes as compared to hydrolysed collagen. We performed an RNA-Sequencing (RNA-seq) experiment where RNA was extracted from tenocyte seeded with BCR. Analysis of enriched pathways of the up-regulated genes revealed that the most enriched pathways were the Hypoxia-inducible factor 1-alpha (HIF1A) regulated networks, implicating the possible mechanism BCR induced ACL regeneration. The subsequent cadaver study was conducted to proof the feasibility of BCR for ACL reconstruction. This study demonstrated the proof-of-concept of bio-textile braided collagen rope for ACL reconstruction, and the mechanism by which BCR induces natural collagen fibres that positively regulate morphology and function of tenocytes

The principal of “function priority, early rehabilitation, and return to sports” is now the goal for sports injury rehabilitation. Neuromuscular electrical stimulation for anterior cruciate ligament (ACL) reconstruction is a rising procedure for early rehabilitation. This paper systematically assessed the effects of neuromuscular electrical stimulation on postoperative ACL reconstruction to provide guidance for physiotherapist and patient when designing a suitable rehabilitation protocol. To evaluate the interventional outcomes of neuromuscular electrical stimulation following ACL reconstruction, we searched PubMed, EMbase, the Cochrane Library, Web of Science and CNKI to collect all randomized controlled trials (RCTs) comparing the effects with neuromuscular electrical stimulation and without intervention on rehabilitation after ACL reconstruction up to January 30, 2022. Two investigators independently performed literature screening, data extraction, bias assessment of risk, and used RevMan 5.3 software to conduct a meta-analysis. A total of six RCTs were included, and the results showed that the use of neuromuscular electrical stimulation after anterior cruciate ligament reconstruction significantly improved the International Knee Documentation Committee (IKDC) scores (MD 6.33, 95% CI [-0.43, 12.22]; I2 = 66%; p = 0.040), the Lysholm score (MD 7.94, 95% CI [6.49, 9.39]; I2 = 89%; p < 0.001), and the range of motion (ROM) (MD 9.99, 95% CI [7.97, 12.02]; I2 = 81%; p < 0.001) in the knees when compared to the control group without using neuromuscular electrical stimulation. Existing evidence show that neuromuscular electrical stimulation is beneficial for early rehabilitation after ACL reconstruction. The use of neuromuscular electrical stimulation is encouraged in the design of rehabilitation protocol. However, due to the limited number of RCT studies and the small sample size, further multi-center RCTs with more participants are needed for a higher-level evidence

Abstract. Introduction. The aim of this study was to determine the factors affecting return to sport (RTS) and career longevity of elite athletes after microfracture of the knee. Methods. A retrospective review of a consecutive series of elite athletes with chondral injuries in the knee treated with microfracture was undertaken. RTS was defined as competing in at least one event at professional level or national/ international level in amateur sport. Demographic, pre, intra and post operative factors affecting RTS were analysed. Results. Fifty six athletes, including 35 (62.5%) footballers and 14 (25.0 %) rugby players, with a mean age 24.8 (+/− 3.9) years, were included. 18 (32.1 %) of chondral injuries were secondary to trauma, 20 (35.7 %) post meniscectomy, 9 (16.1%) post anterior cruciate ligament (ACL) reconstruction and 9 (16.1%) idiopathic. Fifty (89.3%) of athletes RTS at a mean time of 10.0 (+/−5.8) months. 43 (86.0%) athletes were still playing at 2 years. At 5 years 25 (59.5%) of the players who had RTS and had surgery more than 5 years ago were still playing professional sport. Factors associated with not playing at 5 years were cartilage lesions >1.5cm2(52.4% vs 66.7%), more than 1 lesion (35.7% vs74.1%), lateral meniscal surgery (42.1% vs 73.7%) and effusion on RTS (47.7% vs 72.2%). Conclusion. Over 89 % of elite athletes returned to professional sport after microfracture in the knee. However, the ability to continue playing is affected by several factors such as the extent of the chondral damage and recurrent effusions

The bone-patellar tendon-bone (BTB) autograft is associated with difficulty kneeling following anterior cruciate ligament (ACL) reconstruction, however it is unclear whether it results in a more painful or symptomatic knee when compared to the hamstring tendon autograft. This study aimed to identify the rate of significant knee pain and difficulty kneeling following primary ACL reconstruction and clarify whether graft type influences the risk of these complications. Primary ACL reconstructions prospectively recorded in the New Zealand ACL Registry between April 2014 and November 2019 were analyzed. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was analyzed to identify patients who reported significant knee pain, defined as a KOOS Pain subscale score of ≤72 points, and kneeling difficulty, defined as a patient who reported “severe” or “extreme” difficulty when they kneel. The rate of knee pain and kneeling difficulty was compared between graft types via univariate Chi-square test and multivariate binary logistic regression with adjustment for patient demographics. 4492 primary ACL reconstructions were analyzed. At 2-year follow-up, 9.3% of patients reported significant knee pain (420/4492) and 12.0% reported difficulty with kneeling (537/4492). Patients with a BTB autograft reported a higher rate of kneeling difficulty compared to patients with a hamstring tendon autograft (21.3% versus 9.4%, adjusted odds ratio = 3.12, p<0.001). There was no difference between graft types in the rate of significant knee pain (9.9% versus 9.2%, p = 0.49) or when comparing absolute values of the KOOS Pain (mean score for BTB = 88.7 versus 89.0, p = 0.37) and KOOS Symptoms subscales (mean score for BTB = 82.5 versus 82.1, p = 0.49). The BTB autograft is a risk factor for post-operative kneeling difficulty, but it does not result in a more painful or symptomatic knee when compared to the hamstring tendon autograft

The aim of the this study was to determine the effect of the knee flexion angle (KFA) during tibial anterior cruciate ligament (ACL) graft fixation on patient reported outcomes, graft stability, extension loss and re-operation following anatomic single-bundle ACL reconstruction. All 169 included patients (mean age 28.5 years, 65% male) were treated with anatomic single bundle ACL reconstruction using patellar tendon autograft and randomized to tibial fixation of the ACL graft at either 0o (n=85) or 30o (n=84). The primary outcome was the Knee Injury and Osteoarthritis Outcome Score (KOOS) two years following surgery. Secondary outcomes were the Marx Activity Scale (MAS), the rate of re-operation, and physical exam findings at one year including KT-1000 and side to side differences in knee extension. The follow-up rate was 82% (n=139) for the primary outcome. Graft failure rate at two years was 1% (n=2, 1 per group). ACL tibial graft fixation at 0o or 30o did not have a significant effect on KOOS scores at two years following ACLR. Patients whose graft was fixed at a knee flexion angle of 0o had greater scores on the Marx Activity Scale (mean 9.6 [95%CI 8.5-10.6] versus 8.0 [95%CI 6.9-9.1, p=0.04) and a greater proportion of patients who achieved the minimal clinical important difference (MCID) for the KOOS pain subscale (94% vs 81%, p=0.04). There was no significant difference in knee extension loss, KT-1000 measurements or re-operation between the two groups. In the setting of anatomic single-bundle ACLR using patellar tendon autograft and anteromedial portal femoral drilling, there was no difference in KOOS scores among patients fixed at 0o and 30o. Patient fixed in full extension did demonstrate higher activity scores at 2 years following surgery and a greater likelihood of achieving the MCID for KOOS pain

The aim of this study was to determine Anterior Cruciate Ligament (ACL) graft and contralateral ACL (CACL) survival in patients who have undergone ACL reconstruction (ACLR) with hamstring autograft following netball injuries, and determine factors associated with repeat ACL injury and return to netball. From a prospectively collected database, a consecutive series of 332 female netballers who underwent primary ACLRs using hamstring autografts were identified. Subjects were surveyed at a minimum of five years following reconstruction, including details of further ACL injuries to either knee, return to netball or other sports and psychological readiness with the ACL-RSI score. 264 participants (80%) were reviewed at the mean follow up of 9 years (60-180 months). There were 12 ACL graft ruptures (5%) and 35 contralateral ACL ruptures (13%). ACL graft survival was 97% and 97%, 96% at 2, 5 and 7 years respectively. CACL survival was 99%, 94%, and 90% at 2, 5 and 7 years respectively. The 7-year ACL graft survival was 97% in those 25 or more and 93% in those under 25 years (p=0.126). The 7-year CACL survival was 93% in those 25 or more and 85% in those under 25 years (HR 2.6, 95%CI 1.3-5.0, p=0.007). A family history of ACL injury was reported by 32% of participants. A return to netball was reported by 61% of participants. The mean ACL-RSI score was 65 in those who returned to netball and 37 in those who did not (p=0.001). ACLR with hamstring autografts is a reliable procedure for netballers with a survival rate of 96% at 7 years, allowing 63% of participants to return to netball. A successful return to sport was associated with greater psychological readiness. CACL injury occurred with more than double the frequency of ACL graft rupture and was increased by 2.6x in those <25 years

The optimal method of tibial fixation when using a hamstring tendon autograft in anterior cruciate ligament (ACL) reconstruction is unclear. This study aimed to compare the risk of revision ACL reconstruction between suspensory and interference devices on the tibial side. Prospective data on primary ACL reconstructions recorded in the New Zealand ACL Registry between April 2014 and December 2019 were analyzed. Only patients with a hamstring tendon autograft fixed with a suspensory device on the femoral side were included. The rate of revision ACL reconstruction was compared between suspensory and interference devices on the tibial side. Univariate Chi-Square test and multivariate Cox regression was performed to compute hazard ratios (HR) and 95% confidence intervals (CI) with adjustment for age, gender, time-to-surgery, activity at the time of injury, number of graft strands and graft diameter. 6145 cases were analyzed, of which 59.6% were fixed with a suspensory device on the tibial side (n = 3662), 17.6% fixed with an interference screw with a sheath (n = 1079) and 22.8% fixed with an interference screw without a sheath (n = 1404). When compared to suspensory devices (revision rate = 3.4%), a higher risk of revision was observed when using an interference screw with a sheath (revision rate = 6.2%, adjusted HR = 2.05, 95% CI 1.20 – 3.52, p = 0.009) and without a sheath (revision rate = 4.6%, adjusted HR = 1.81, 95% CI 1.02 – 3.23, p = 0.044). The number of graft strands and a graft diameter of ≥8 mm did not influence the risk of revision. When reconstructing the ACL with a hamstring tendon autograft, the use of an interference screw, with or without a sheath, on the tibial side has a higher risk of revision when compared to a suspensory device

Abstract. Introduction. All-tissue quadriceps tendon (QT) is becoming an increasingly popular alternative to hamstrings tendon (HT) and bone-tendon-bone (BTB) autograft for anterior cruciate ligament (ACL) reconstruction. The relatively short graft length however dictates that one, or both, ends rely on suture fixation. The strength of this construct is therefore extremely important. This study evaluates whether the use of a novel fixation technique can improve the tensile properties of the construct compared to a Krackow suture, and a looped tendon (suture free) gold standard. Methods. Eighteen porcine flexor tendons were tested, across three groups; suture-tape Krackow, looped tendon, and the novel ‘strain suture’. Biomechanical testing simulated the different stages of ACL graft preparation and loading (60N preload for 10 minutes, 10 cycles from 10N to 75N, and 1000 cycles from 100N to 400N). Elongation and load to failure were recorded, and stiffness calculated for each construct. Results. The mean elongation was significantly improved for the strain suture compared to the suture tape Krackow for preload, 10 cycle and 1000 cycle testing protocols respectively (1.36mm vs 4.93mm, p<001; 0.60mm vs 2.72mm, p<0.001; 2.95mm vs 29.08mm, p<0.001). Compared with the looped tendon, the strain suture demonstrated similar results for preload and 10 cycle elongation, but greater elongation during the 1000 cycle stage. Stiffness of the latter two constructs was similar. Conclusions. Augmentation of the suture fixation using this novel technique provides a construct that is significantly superior to currently practised suture techniques, and similar in elongation and stiffness to a looped graft

Although autografts represent the gold standard for anterior cruciate ligament (ACL) reconstruction, tissue-engineered ACLs provide a prospect to minimize donor site morbidity and limited graft availability. This given study characterizes the ligamentogenesis in embroidered poly(L-lactide-co-ε-caprolactone) (P(LA-CL)) / polylactic acid (PLA) constructs using a dynamic nude mice xenograft model. (P(LA-CL))/PLA scaffolds remained either untreated (co) or were functionalized by gas fluorination (F), collagen foam cross-linked with hexamethylene diisocyanate (HMDI) (coll), or gas fluorination combined with the foam (F+coll). Cell free constructs or those seeded for 1 week with lapine ACL ligamentocytes were implanted into nude mice for 12 weeks. Following explantation, biomechanical properties, cell vitality and content, histopathology of scaffolds (including organs: liver, kidney, spleen), sulphated glycosaminoglycan (sGAG) contents and biomechanical properties were assessed. Implantation of the scaffolds did not negatively affect mice weight development and organs, indicating biocompatibility. All scaffolds maintained their size and shape for the duration of the implantation. A high cell viability was detected in the scaffolds prior to and following implantation. Coll or F+coll scaffolds seeded with cells yielded superior macroscopic properties when compared to the controls. Mild signs of inflammation (foreign-body giant cells, hyperemia) were limited to scaffolds without collagen. Microscopical score values and sGAG content did not differ significantly. Although remaining stable in vivo, elastic modulus, maximum force, tensile strength and strain at Fmax were significantly lower in the in vivo compared to the samples cultured 1 week in vitro, but did not differ between scaffold subtypes, except for a higher maximum force in F+coll compared with F samples (in vivo). Scaffold functionalization with fluorinated collagen foam provides a promising approach for ACL tissue engineering. (shared first authorship). Acknowledgement: The study was supported by DFG grants SCHU1979/9-1 and SCHU1979/14-1

To investigate temporal changes in synovial lymphatic system (SLS) drainage function after Anterior cruciate ligament (ACL) injury, a non-invasive ACL rupture model was used to induce the PTOA phenotype without altering the SLS structure. We have created a non-invasive ACL rupture model in the right knee (single overload impact) of 12- week-old C57bl/6 male mice to mimic the ACL rupture-induced PTOA development. 70 kDa-TxRedDextran were injected into the right knee of the mice at 0, 1, 2, and 4 wks post modeling (n=5/group), and the fluorescence signal distribution and intensity were measured by the IVIS system at 1 and 6 hrs post-injection. After 24 hrs, the drainage lymph nodes and whole knee joint were harvested and subjected to ex vivo IVIS imaging and immunofluorescence detection respectively. Manual ACL rupture was induced by 12N overloaded force and validated by a front drawer test. Intraarticular clearance of TxRed-Dextran detected by the IVIS was significantly reduced at 1, and 2 wks at a level of 43% and 55% respectively but was not significantly different from baseline levels at 4 wks (89%). TxRed-Dextran signal in draining lymph nodes was significantly reduced at 1 week at the level of but not for 2 and 4 wks compared to baseline levels (week 1–29%, week 2–50%, week 4–94%). TxRed-Dextran particle was significantly enriched in the synovium at 1, 2 wks but was not significantly different from baseline levels at 4 wks rupture-post ACL rupture (Particle numbers: Sham Ctrl-34 ±14, week 1, 113 ± 17; week 2, 89 ± 13; week 4, 46 ± 18; mean ± SD). We observed the drainage function of SLS significantly decreased at 1 and 2 wks after the ACL rupture, and was slowly restored at 4 wks post-injury in a non-invasive ACL rupture model. Early impairment of SLS drainage function may lead to accumulation of inflammatory factors and promote PTOA progression

Introduction. Day stay surgery for anterior cruciate ligament (ACL) reconstructions is an increasingly common practice and has driven clinicians to come up with postoperative pain regimes that allow same day mobilisation and a safe and timely discharge. There is a paucity of literature surrounding the use of intraosseous (IO) ropivacaine used as a Bier's block to provide both intraoperative and postoperative analgesia in lower limb surgery. Methods. This patient blinded, pilot study randomised 15 patients undergoing ACL reconstruction to receive either IO ropivacaine 1.5 or 2.0 mg/kg; or 300 mg of ropivacaine as local infiltration (standard of care). Toxic plasma levels of ropivacaine have been defined in the literature and therefore the primary outcome for this study was arterial plasma concentration of ropivacaine as a means to determine its safety profile. Samples were taken via an arterial line at prespecified times after tourniquet deflation. Secondary outcomes that we were interested in included immediate postoperative pain scores using the visual analogue scale (VAS) and perioperative opioid equivalent consumption. Results. Participants had a mean age of 27.8 (SD 9.2) years and 87% (13/15) were male. All patients in the intervention group receiving IO ropivacaine had plasma concentrations well below the threshold for central nervous system (CNS) toxicity (0.60 µg/ml). The highest plasma concentration was achieved in the intervention group receiving 1.5 mg/kg dose of ropivacaine reaching 3.59 mg/ml. This would equate to 0.22 µg/ml of free plasma ropivacaine. There were no differences across the three groups regarding pain scores or perioperative opioid consumption. Conclusions. This study demonstrates that IO administration of 0.2% ropivacaine is both safe and effective in reducing perioperative pain in patients undergoing ACL reconstruction. There may be scope to increase the IO dose further or utilise other analgesics via the IO regional route to improve perioperative pain relief

Anterior cruciate ligament (ACL) ruptures are debilitating injuries, often managed via ACL reconstruction (ACLR). Reduced range of motion (ROM), particularly loss of extension (LOE), is the most significant contributor to post-operative patient dissatisfaction. LOE may preclude return to sport, increase re-rupture rates and precipitate osteoarthritis. Passive LOE rates following ACLR have been reported at 15%. However, LOE incidence during active tasks are poorly characterised. Our review sought to determine knee extension angles for active tasks following an ACL injury or ACLR. We hypothesised greater incidences of active LOE following ACL injury or ACLR, compared to uninjured contralateral limbs or controls. We systematically searched MEDLINE, Embase, Cochrane Library, Scopus, SPORTDiscus, and relevant trials databases for English articles. Included were cohort, cross-sectional, case-controlled or randomised controlled trials analysing adults with ACL injury treated surgically or otherwise, with at least 12-weeks follow-up and reporting either active knee extension angle, active LOE angles or incidence of active knee LOE during functional tasks. The protocol was registered on PROSPERO (CRD42018092295). Subsequent meta-analysis was performed. After screening, 71 eligible articles were included. Studies were heterogenous in design and quality. Included tasks were overground walking (n=44), running (n=3), hopping/jumping/cutting (n=11) single-leg landing (n=7), and stair climbing (n=6). LOE incidence varied depending on functional activities (33.95-92.74%). LOE incidence did not vary depending on ACL status (67.26% vs. 65.90% vs. 62.57% for ACL intact, ACLD and ACLR, respectively). We observed no difference in active LOE incidence according to ACL status. Importantly, the observed incidence for active LOE was reliably higher than previously reported rates for passive measures. Given the discrepancy between active and passive LOE incidence, clinicians may advisably prioritise active ROM during ACL rehabilitation

Introduction. Anterior Cruciate Ligament (ACL) injury prevention programs can reduce injury risk in various sports. The perception of ACL injury prevention programs amongst professional netball players and coaches has not been studied. The purpose of the study was to determine (1) level of awareness and experience of ACL injury prevention programs; (2) use of ACL injury prevention programs; and (3) barriers and potential facilitators to implementing a sustainable ACL injury prevention program in netball. Methods. This cross-sectional observational study was undertaken using the CHERRIES checklist. Female netball players representing Welsh senior and under-21 teams and elite and amateur coaches were invited electronically to participate in this web-based study between 1st May – 31st July 2021. Information on ACL injury susceptibility and seriousness, knowledge, experience, and implementation of ACL injury prevention programs were ascertained. Results. Twenty-eight players (77.8%) and 29 coaches (13.2%) completed the questionnaire. Seventeen (60.7%) players and 15 (51.7%) coaches reported female athletes were at greater risk for sustaining ACL injuries. Over 90% of respondents identified netball as high-risk, whilst 89% of players and 76% of coaches reported these injuries to be preventable. Only two (7.1%) players and 6 (20.7%) coaches utilised an ACL injury prevention program with lack of time and engagement from coaches and players identified. Majority of respondents indicated that their club has neither promoted, advocated the use nor demonstrated exercises for ACL injury prevention. Over 90% of respondents would utilise an ACL injury prevention program if it minimised players risk with appropriate information and demonstration of exercises. Conclusion. This study highlights limited knowledge of female athletes' increased susceptibility of ACL injuries amongst players and coaches with lack of communication and education of ACL injury prevention programs between sporting associations, coaches, and players. However, the results demonstrate willingness amongst both players and coaches to implement an ACL injury prevention program in netball

Successful anterior cruciate ligament (ACL) reconstructions strive a firm ligament-bone integration. Therefore, the aim of this study was to address in more detail the enthesis as the thriphasic bone attachment of the ACL using a tissue engineering approach. To establish a tissue-engineered enthesis-like construct, triphasic scaffolds embroidered from poly(L-lactide-co-caprolactone) and polylactic acid functionalized with collagen foam were colonized with osteogenically differentiated human mesenchymal stromal cells (hMSCs) and lapine (L) ACL fibroblasts. These triphasic scaffolds with a bone-, a fibrocartilage transition- and a ligament phase were seeded directly after spheroid assembly or with 14 days precultured LACL fibroblast spheroids and 14 days osteogenically differentiated hMSCs spheroids (=longer preculture) and cultured for further 14 days. Cell survival was tested. Collagen type I and vimentin were immunolabeled and the content of DNA and sulfated glycosaminoglycan (sGAG) was quantified. The relative gene expression of tenascin C, type I and X collagens, Mohawk and Runx2 was analyzed. Compared to the LACL spheroids the hMSC spheroids adhered better to the scaffold surface with faster cell outgrowth on the fibers. Collagen type I and vimentin were mainly detected in the hMSCs colonizing the bone zone. The DNA content was generally higher in the bone (hMSCs) than in the ligament zones and after short spheroid preculture higher than after longer preculture whereas the sGAG content was greater after longer preculture for both cell types. The longer precultivated hMSCs expressed more type I collagen in comparison to those only shortly precultured before scaffold seeding. Type I collagen and tenascin C were higher expressed in scaffolds directly colonized with LACL compared to those seeded after longer spheroid preculture. The gene expression of ECM components and transcription factors depended on cell type and preculturing condition. Zonal colonization of triphasic scaffolds using the spheroid method is possible offering a novel approach for enthesis tissue engineering

Most previous studies investigating autograft options (quadriceps, hamstring, bone-patella-tendon-bone) in primary anterior cruciate ligament (ACL) reconstruction are confounded by concomitant knee injuries. This study aims to investigate the differences in patient reported outcome measures and revision rates for quadriceps tendon in comparison with hamstring tendon and bone-patella-tendon-bone autografts. We use a cohort of patients who have had primary ACL reconstruction without concomitant knee injuries. All patients from the New Zealand ACL Registry who underwent a primary arthroscopic ACL reconstruction with minimum 2 year follow-up were considered for the study. Patients who had associated ipsilateral knee injuries, previous knee surgery, or open procedures were excluded. The primary outcome was Knee Injury and Osteoarthritis Outcome Score (KOOS) and MARX scores at 2 years post-surgery. Secondary outcomes were all-cause revision and time to revision with a total follow-up period of 8 years (time since inception of the registry). 2581 patients were included in the study; 1917 hamstring tendon, 557 bone-patella-tendon-bone, and 107 quadriceps tendon. At 2 years, no significant difference in MARX scores were found between the three groups (2y mean score; 7.36 hamstring, 7.85 bone-patella-tendon-bone, 8.05 quadriceps, P = 0.195). Further, no significant difference in KOOS scores were found between the three groups; with the exception of hamstring performing better than bone-patella-tendon-bone in the KOOS sports and recreation sub-score (2y mean score; 79.2 hamstring, 73.9 bone-patella-tendon-bone, P < 0.001). Similar revision rates were reported between all autograft groups (mean revision rate per 100 component years; 1.05 hamstring, 0.80 bone-patella-tendon-bone, 1.68 quadriceps, P = 0.083). Autograft revision rates were independent of age and gender variables. Quadriceps tendon is a comparable autograft choice to the status quo for primary ACL reconstruction without concomitant knee injury. Further research is required to quantify the long-term outcomes for quadriceps tendon use

Meniscal repairs are commonly performed during anterior cruciate ligament (ACL) reconstruction. This study aimed to identify the risk factors for meniscal repair failure following concurrent primary ACL reconstruction. Primary ACL reconstructions with a concurrent repair of a meniscal tear recorded in the New Zealand ACL Registry between April 2014 and December 2018 were analyzed. Meniscal repair failure was defined as a patient who underwent subsequent meniscectomy, and was identified after cross-referencing data from the ACL Registry with the national database of the Accident Compensation Corporation (ACC). Multivariate Cox regression was performed to produce hazard ratios (HR) with 95% confidence intervals (CI) to identify the patient and surgical risk factors for meniscal repair failure. 2041 meniscal repairs were analyzed (medial = 1235 and lateral = 806). The overall failure rate was 9.4% (n = 192). Failure occurred in 11.1% of medial (137/1235) and 6.8% of lateral (55/806) meniscal repairs. The risk of medial failure was higher with hamstring tendon autografts (adjusted HR = 2.00, 95% CI 1.23 – 3.26, p = 0.006) and in patients with cartilage injury in the medial compartment (adjusted HR = 1.56, 95% CI 1.09 – 2.23, p = 0.015). The risk of lateral failure was higher when the procedure was performed by a surgeon with an annual case volume of less than 30 ACL reconstructions (adjusted HR = 1.92, 95% CI 1.10 – 3.33, p = 0.021). Age, gender, time from injury-to-surgery and femoral tunnel drilling technique did not influence the risk of meniscal repair failure. When repairing a meniscal tear during ACL reconstruction, the use of a hamstring tendon autograft or the presence of cartilage injury in the medial compartment increases the risk of medial meniscal repair failure. Lower surgeon case volume increases the risk of lateral meniscal repair failure

Aims. The anterior cruciate ligament (ACL) is known to have a poor wound healing capacity, whereas other ligaments outside of the knee joint capsule such as the medial collateral ligament (MCL) apparently heal more easily. Plasmin has been identified as a major component in the synovial fluid that varies among patients. The aim of this study was to test whether plasmin, a component of synovial fluid, could be a main factor responsible for the poor wound healing capacity of the ACL. Methods. The effects of increasing concentrations of plasmin (0, 0.1, 1, 10, and 50 µg/ml) onto the wound closing speed (WCS) of primary ACL-derived ligamentocytes (ACL-LCs) were tested using wound scratch assay and time-lapse phase-contrast microscopy. Additionally, relative expression changes (quantitative PCR (qPCR)) of major LC-relevant genes and catabolic genes were investigated. The positive controls were 10% fetal calf serum (FCS) and platelet-derived growth factor (PDGF). Results. WCS did not differ significantly among no plasmin versus each of the tested concentrations (six donors). The positive controls with PDGF and with FCS differed significantly from the negative controls. However, we found a trend demonstrating that higher plasmin concentrations up-regulate the expression of matrix metalloproteinase 13 (MMP13), 3 (MMP3), and tenomodulin (TNMD). Conclusion. The clinical relevance of this study is the possibility that it is not solely the plasmin, but also additional factors in the synovial fluid of the knee, that may be responsible for the poor healing capacity of the ACL. Cite this article: Bone Joint Res 2020;9(9):543–553

Arthrofibrosis is a less common complication following anterior cruciate ligament (ACL) reconstruction and there are concerns that undergoing early surgery may be associated with arthrofibrosis. The aim of this study was to identify the patient and surgical risk factors for arthrofibrosis following primary ACL reconstruction. Primary ACL reconstructions prospectively recorded in the New Zealand ACL Registry between April 2014 and December 2019 were analyzed. The Accident Compensation Corporation (ACC) database was used to identify patients who underwent a subsequent reoperation with review of operation notes to identify those who had a reoperation for “arthrofibrosis” or “stiffness”. Univariate Chi-Square test and multivariate Cox regression analysis was performed. Hazard ratios (HR) with 95% confidence intervals (CI) were computed to identify the risk factors for arthrofibrosis. 9617 primary ACL reconstructions were analyzed, of which 215 patients underwent a subsequent reoperation for arthrofibrosis (2.2%). A higher risk of arthrofibrosis was observed in female patients (adjusted HR = 1.67, 95% CI 1.22 – 2.27, p = 0.001), patients with a history of previous knee surgery (adjusted HR = 1.97, 95% CI 1.11 – 3.50, p = 0.021) and when a transtibial femoral tunnel drilling technique was used (adjusted HR = 1.55, 95% CI 1.06 – 2.28, p = 0.024). Patients who underwent early ACL reconstruction within 6 weeks of their injury did not have a higher risk of arthrofibrosis when compared to patients who underwent surgery more than 6 weeks after their injury (3.5% versus 2.1%, adjusted HR = 1.56, 95% CI 0.97 – 2.50, p = 0.07). Age, graft type and concomitant meniscal injury did not influence the rate of arthrofibrosis. Female sex, a history of previous knee surgery and a transtibial femoral tunnel drilling technique are risk factors for arthrofibrosis following primary ACL reconstruction

Screw fixation is an established method for anterior cruciate ligament (ACL) reconstruction, although with a high rate of implant-related complications. An allograft system for implant fixation in ACL reconstruction, the Shark Screw ACL (surgebright GmbH) could overcome some of the shortcomings of bioabsorbable screws, such as foreign body reaction, need for implant removal and imaging artefacts. However, it needs to provide sufficient mechanical stability. Therefore, the aim of this study was to investigate the biomechanical stability, especially graft slippage, of the novel allograft system versus a conventional bioabsorbable interference screw (BioComposite Interference Screw; Arthrex Inc.) for tibial implant fixation in ACL reconstruction. Twenty-four paired human proximal tibiae (3 female, 9 male, 72.7 ± 5.6 years) underwent ACL reconstruction. The quadrupled semitendinosus and gracilis tendon graft were fixed in one specimen of each pair using the allograft fixation system Shak Screw ACL and the contralateral one using an interference screw. All specimens were cyclically loaded at 1 Hz with peak load levels monotonically increased from 50 N at a rate of 0.1 N/cycle until catastrophic failure. Relative movements of the graft versus the tibia were captured with a stereographic optical motion tracking system (Aramis SRX; GOM GmbH). The two fixation methods did not demonstrate any statistical difference in ultimate load at graft slippage (p = 0.24) or estimated survival at slippage (p = 0.06). Both, the ultimate load and estimated survival until failure were higher in the interference screw (p = 0.04, and p = 0.018, respectively). Graft displacement at ultimate load reached values of up to 7.2 mm (interference screw) and 11.3 mm (Shark Screw ACL). The allograft screw for implant fixation in ACL reconstruction showed similar behavior in terms of graft slippage compared to the conventional metal interference screw but underperformed in terms of ultimate load. However, the ultimate load may not be considered a direct indicator of clinical failure

Objectives. Unicompartmental knee arthroplasty (UKA) is one surgical option for treating symptomatic medial osteoarthritis. Clinical studies have shown the functional benefits of UKA; however, the optimal alignment of the tibial component is still debated. The purpose of this study was to evaluate the effects of tibial coronal and sagittal plane alignment in UKA on knee kinematics and cruciate ligament tension, using a musculoskeletal computer simulation. Methods. The tibial component was first aligned perpendicular to the mechanical axis of the tibia, with a 7° posterior slope (basic model). Subsequently, coronal and sagittal plane alignments were changed in a simulation programme. Kinematics and cruciate ligament tensions were simulated during weight-bearing deep knee bend and gait motions. Translation was defined as the distance between the most medial and the most lateral femoral positions throughout the cycle. Results. The femur was positioned more medially relative to the tibia, with increasing varus alignment of the tibial component. Medial/lateral (ML) translation was smallest in the 2° varus model. A greater posterior slope posteriorized the medial condyle and increased anterior cruciate ligament (ACL) tension. ML translation was increased in the > 7° posterior slope model and the 0° model. Conclusion. The current study suggests that the preferred tibial component alignment is between neutral and 2° varus in the coronal plane, and between 3° and 7° posterior slope in the sagittal plane. Varus > 4° or valgus alignment and excessive posterior slope caused excessive ML translation, which could be related to feelings of instability and could potentially have negative effects on clinical outcomes and implant durability. Cite this article: K. Sekiguchi, S. Nakamura, S. Kuriyama, K. Nishitani, H. Ito, Y. Tanaka, M. Watanabe, S. Matsuda. Bone Joint Res 2019;8:126–135. DOI: 10.1302/2046-3758.83.BJR-2018-0208.R2

Background. Anterior cruciate ligament (ACL) reconstruction with concomitant meniscal injury occurs frequently. Meniscal repair is associated with improved long-term outcomes compared to resection but is also associated with a higher reoperation rate. Knowledge of the risk factors for repair failure may be important in optimizing patient outcomes. Purpose. This study aimed to identify the patient and surgical risk factors for meniscal repair failure, defined as a subsequent meniscectomy, following concurrent primary ACL reconstruction. Methods. Data recorded by the New Zealand ACL Registry and the Accident Compensation Corporation, the New Zealand Government's sole funder of ACL reconstructions and any subsequent surgery, was reviewed. Meniscal repairs performed with concurrent primary ACL reconstruction was included. Root repairs were excluded. Univariate and multivariate survival analysis was performed to identify the patient and surgical risk factors for meniscal repair failure. Results. Between 2014 and 2020, a total of 3,024 meniscal repairs were performed during concurrent primary ACL reconstruction (medial repair = 1,814 and lateral repair = 1,210). The overall failure rate was 6.6% (n = 201) at a mean follow-up of 2.9 years, with a failure occurring in 7.8% of medial meniscal repairs (142 out of 1,814) and 4.9% of lateral meniscal repairs (59 out of 1,210). The risk of medial failure was higher in patients with a hamstring tendon autograft (adjusted HR = 2.20, p = 0.001), patients aged 21–30 years (adjusted HR = 1.60, p = 0.037) and in those with cartilage injury in the medial compartment (adjusted HR = 1.75, p = 0.002). The risk of lateral failure was higher in patients aged ≤ 20 years (adjusted HR = 2.79, p = 0.021) and when the procedure was performed by a surgeon with an annual ACL reconstruction case volume of less than 30 (adjusted HR = 1.84, p = 0.026). Conclusion. When performing meniscal repair during a primary ACL reconstruction, the use of a hamstring tendon autograft, younger age and the presence of concomitant cartilage injury in the medial compartment increases the risk of medial meniscal repair failure, whereas younger age and low surgeon volume increases the risk of lateral meniscal repair failure

Introduction. Anterior cruciate ligament (ACL) injuries are one of the most common knee injuries amongst elite athletes and usually require an ACL reconstruction (ACLR) to enable return to sport. Secondary surgery can result in a longer rehabilitation period and often a. significant time away from sport which can have implications to the athlete including contract obligations and sponsorship. Advances in ACLR techniques and meniscal repair techniques as well as an awareness of meniscal root lesions, ramp lesions and lateral extraarticular procedures (LEAPs) during ACL surgery has improved outcomes. The purpose of this study was to evaluate the rates of secondary surgery following the introduction of a systematic arthroscopic evaluation of the knee, improved meniscal repair techniques and the addition of a concomitant LEAP This systematic approach was introduced after October 2012 (10/2012). Methods. Professional athletes who underwent primary ACLR with a minimum follow-up of 2 years were identified from the (blinded for review). Those who had undergone major concomitant procedures such as multi-ligament reconstruction or osteotomy were excluded. Analysis of the database and review of medical records identified athletes who had underwent secondary surgery procedures. Results. A total of 342 athletes with a mean follow-up of 100.2 +/− 51.9 months (range, 24–215 months) were analysed. 130 athletes underwent surgery before 10/2012 and 212 athletes underwent surgery after 10/2012. Overall, 74 patients (21.6%) underwent secondary surgery. 39 patients (30.0% including 13.1% for graft rupture) before 10/2012 and 35 patients (16.5% including 6.6% for graft rupture) after 10/2012. A multivariate analysis was performed using the Cox model and demonstrated that athletes undergoing ACLR before10/2012 were at almost 2-fold risk of secondary surgery (hazard ratio (HR), 1.768(1.103;2.836), p=0.0256) when compared with those undergoing ACLR after 10/2012. (Figure 1). Conclusion. Professional athletes undergoing ACLR with a systematic arthroscopic evaluation with the use of advanced meniscal repair techniques and the combination with a LEAP result in a significantly lower rate of secondary surgery. For any figures or tables, please contact authors directly

Introduction. Anterior tibial translation (ATT) is assessed in the acutely injured knee to investigate for ligamentous injury and rotational laxity. Specifically, there is a growing recognition of the significance of anterior medial rotary laxity (AMRI) as a crucial element in assessing knee stability. Anterior cruciate ligament (ACL) injuries are often accompanied with medial collateral ligament (MCL) damage. It has been suggested that Deep MCL (dMCL) fibres are a primary restraint in rotational displacement. This research aims to quantify the difference in rotational laxity of patients with ACL and MCL injuries to deem if the Feagin-Thomas test can robustly capture metrics of AMRI. 2. Methods. AMRI was assessed using the Feagin-Thomas test in 7 isolated ACL (iACL) injured participants, 3 combined ACL and superficial fibre MCL (sMCL) injuries, 5 combined ACL and deep fibre MCL injuries, and 21 healthy controls. Displacement values were recorded using an optical motion capture (OMC) system and bespoke processing pipeline which map and model the knee's anterior displacement values relative to the medial compartment. Since absolute values (mm) of rotational laxity vary dependant on the person, values were recorded as a proportion of the rotational laxity obtained from the subject's contralateral leg. Values were compared between each patient group using an ANOVA test and Tukey's honesty significant difference post hoc test. 3. Results. The healthy control group had a median proportion of 0.97 (3SF), whilst the iACL was 1.12 (3SF), a 12% increase in rotational laxity in the injured leg. The sMCL group yielded a result of 1.64 (3SF), a 64% increase in rotational laxity in the injured leg; finally, dMCL resulted in a proportion of rotational laxity of 1.90 (3SF), a 90% increase in rotational laxity [table 1]. Whilst all groups showed differences in the increase of rotational laxity, dMCL was significantly different from the healthy control group (P value 0.0041). 4. Conclusion. ACL injuries with MCL involvement led to an increase in anterior medial rotary laxity and this is more evident in patients where deep MCL fibres are involved. The Feagin-Thomas test appears to be sensitive in detecting differences in AMRI and should be considered when performing comprehensive clinical knee examination. For any figures or tables, please contact authors directly

Anterior cruciate ligament (ACL) reconstruction is commonly performed and has been for many years. Despite this, the technical details related to ACL anatomy, such as tunnel placement, are still a topic for debate. In this paper, we introduce the flat ribbon concept of the anatomy of the ACL, and its relevance to clinical practice. Cite this article: Bone Joint J 2016;98-B:1020–6

Increasing expectations from arthroscopic anterior cruciate ligament (ACL) reconstructions require precise knowledge of technical details such as minimum intra-femoral tunnel graft lengths. A common belief of having ≥20mm of grafts within the femoral tunnel is backed mostly by hearsay rather than scientific proof. We examined clinico-radiological outcomes in patients with intra-femoral tunnel graft lengths <20 and ≥20mm. Primary outcomes were knee scores at 1-year. Secondarily, graft revascularization was compared using magnetic resonance imaging (MRI). We hypothesized that outcomes would be independent of intra-femoral tunnel graft lengths. This prospective, single-surgeon, cohort study was conducted at a tertiary care teaching centre between 2015–2018 after obtaining ethical clearances and consents. Eligible arthroscopic ACL reconstruction patients were sequentially divided into 2 groups based on the intra-femoral tunnel graft lengths (A: < 20 mm, n = 27; and B: ≥ 20 mm, n = 25). Exclusions were made for those > 45 years of age, with chondral and/or multi-ligamentous injuries and with systemic pathologies. All patients were postoperatively examined and scored (Lysholm and modified Cincinnati scores) at 3, 6 and 12 months. Graft vascularity was assessed by signal-to-noise quotient ratio (SNQR) using MRI. Statistical significance was set at p<0.05. Age and sex-matched patients of both groups were followed to 1 year (1 dropout in each). Mean femoral and tibial tunnel diameters (P =0.225 and 0.595) were comparable. Groups A (<20mm) and B (≥20mm) had 27 and 25 patients respectively. At 3 months, 2 group A patients and 1 group B patient had grade 1 Lachman (increased at 12 months to 4 and 3 patients respectively). Pivot shift was negative in all patients. Lysholm scores at 3 and 6 months were comparable (P3= 0.195 and P6= 0.133). At 1 year both groups showed comparable Cincinnati scores. Mean ROM was satisfactory (≥130 degrees) in all but 2 patients of each group (125–130 degrees). MRI scans at 3 months and 1 year observed anatomical tunnels in all without any complications. Femoral tunnel signals in both groups showed a fall from 3–12 months indicating onset of maturation of graft at femoral tunnel. Our hypothesis, clinical and radiological outcomes would be independent of intra-tunnel graft lengths on the femoral aspect, did therefore prove correct. Intra-femoral tunnel graft lengths of <20 mm did not compromise early clinical and functional outcomes of ACL reconstructions. There seems to be no minimum length of graft within the tunnel below which suboptimal results should be expected

Meniscal tears commonly co-occur with ACL tears, and many studies address their side, pattern, and distribution. Few studies assess the patient's short-term functional outcome concerning tear radial and circumferential distribution based on the Cooper et al. classification. Meniscal tears require primary adequate treatment to restore knee function. Our hypothesis is to preserve the meniscal rim as much as possible to maintain the load-bearing capacity of the menisci after meniscectomy. The purpose of this study is to document the location and type of meniscal tears that accompany anterior cruciate ligament (ACL) tears and their effect on patient functional outcomes following arthroscopic ACL reconstruction and meniscectomy. This prospective cross-sectional observational study was conducted at AL-BASRA Teaching Hospital in Iraq between July 2018 and January 2020 among patients with combined ipsilateral ACL injury and meniscal tears. A total of 28 active young male patients, aged 18 to 42 years, were included. All patients were subjected to our questionnaire, full history, systemic and regional examination, laboratory investigations, imaging studies, preoperative rehabilitation, and were followed by Lysholm score 6 months postoperatively. All 28 patients were males, with a mean age of 27 ± 0.14 years. The right knee was the most commonly affected in 20/28 patients (71.4%). The medial meniscus was most commonly injured in 11 patients, 7 patients had lateral meniscal tears, and 10 patients had tears in both menisci. The most common tear pattern of the medial meniscus was a bucket handle tear (36.4%), while longitudinal tears were the most frequent in the lateral meniscus (71.4%) (P-value = 0.04). The most common radial tear location was zone E-F (5/28, 17.8%), and the most common circumferential zone affected was the middle and inner third, reported in 50% of tears. Good and excellent outcomes using the Lysholm score after 6 months were obtained in 42.9% and 17.9% of patients, respectively. Better functional scores were associated with lateral meniscal tears, bucket handle tears, tears extending to a more peripheral vascular area, and if no more than one-third of the meniscus was resected (P-value = 0.002). Less favourable outcomes were reported in smokers, posterior horn tears, and when surgery was delayed more than 1 year (P-value = 0.03). We conclude that there is a negative correlation between the amount of meniscus resected and functional outcome. Delayed ACL reconstruction increases the risk of bimeniscal tears. Bucket handle tears are the most common tears, mostly in the medial meniscus, while longitudinal tears are most common in the lateral meniscus. We recommend performing early ACL reconstruction within 12 months to reduce the risk of bimeniscal injuries

Rotational laxity increases the risk of anterior cruciate ligament (ACL) injuries and residual rotational laxity can result in inferior surgical outcomes and risk of retears. The dynamic rotatory knee stability can be assessed through manual examination, but it is limited to the surgeon's experience and it provides inaccurate measurements, highlighting the need for objective measurement of knee rotational laxity. The objective measurement of knee laxity can help to better identify patients that may benefit from conservative treatment or those that require surgical treatment with or without concomitant extra-articular procedures. We rely in Porto Knee Testing Device (PKTD®) to accurately measure sagittal and rotatory laxity of the knee, either individually or in a combined fashion. The PKTD® is safe and can be used in combination with CT or MRI, which allows to assess both the “anatomy” and the “function” in the same examination. By this way, we may have a total ACL rupture and a stable knee not requiring surgery or, on the other hand, the same injury scenario but with an unstable knee that requires surgical intervention (with or without lateral extra-articular tenodesis). In cases of partial ACL tears, it may be possible to identify some ligamentous fibers that remain functional, where the conservative treatment or augmentation techniques can provide satisfactory results. It can also identify when a posteromedial or posterolateral instability is associated. The PKTD® can also be used to follow-up the laxity results of conservative and surgical procedures and contribute to the decision-making of return to sports

Aims. Anterior cruciate ligament (ACL) and multiligament knee (MLK) injuries increase the risk of development of knee osteoarthritis and eventual need for total knee arthroplasty (TKA). There are limited data regarding implant use and outcomes in these patients. The aim of this study was to compare the use of constrained implants and outcomes among patients undergoing TKA with a history of prior knee ligament reconstruction (PKLR) versus a matched cohort of patients undergoing TKA with no history of PKLR. Patients and Methods. Patients with a history of ACL or MLK reconstruction who underwent TKA between 2007 and 2017 were identified in a single-institution registry. There were 223 patients who met inclusion criteria (188 ACL reconstruction patients, 35 MLK reconstruction patients). A matched cohort, also of 223 patients, was identified based on patient age, body mass index (BMI), sex, and year of surgery. There were 144 male patients and 79 female patients in both cohorts. Mean age at the time of TKA was 57.2 years (31 to 88). Mean BMI was 29.7 kg/m. 2. (19.5 to 55.7). Results. There was a significantly higher use of constrained implants among patients with PKLR (76 of 223, 34.1%) compared with the control group (40 of 223, 17.9%; p < 0.001). Subgroup analysis showed a higher use of constrained implants among patients with prior MLK reconstruction (21 of 35, 60.0%) compared with ACL reconstruction (55 of 188, 29.3%; p < 0.001). Removal of hardware was performed in 69.5% of patients with PKLR. Mean operative time (p < 0.001) and tourniquet time (p < 0.001) were longer in patients with PKLR compared with controls. There were no significant differences in rates of deep vein thrombosis, pulmonary embolism, infection, transfusion, postoperative knee range of movement (ROM), or need for revision surgery. There was no significant difference in preoperative or postoperative Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) scores between groups. Conclusion. Results of this study suggest a history of PKLR results in increased use of constrained implants but no difference in postoperative knee ROM, patient-reported outcomes, or incidence of revision surgery. Cite this article: Bone Joint J 2019;101-B(7 Supple C):77–83

Aims. The aim of this study was to investigate the incidence, risk factors, and outcome of venous thromboembolism (VTE) following anterior cruciate ligament (ACL) reconstruction in a nationwide cohort. Patients and Methods. All ACL reconstructions, primary and revision, that were recorded in the Swedish Knee Ligament Register (SKLR) between 2006 and 2013 were linked with data from the Swedish National Board of Health and Welfare. The incidence of VTE was determined by entries between the day of surgery until 90 days postoperatively based on diagnosis codes and the prescription of anticoagulants. Risk factors, outcome, and the use of thromboprophylaxis were analyzed. Descriptive statistics with multivariate analysis were used to describe the findings. Results. The cohort consisted of 26 014 primary and revision ACL reconstructions. There were 89 deep venous thromboses (DVTs) and 12 pulmonary emboli (PEs) with a total of 95 VTEs (0.4 %). Six patients with a PE had a simultaneous DVT. The only independent risk factor for VTE was age greater than or equal to 40 years (odds ratio 2.31, 95% confidence interval 1.45 to 3.70; p < 0.001). Thromboprophylaxis was prescribed to 9461 patients (36%) and was equally distributed between those with and those without a VTE (37.9% vs 36.4%). All patient-reported outcome measures (PROMs) one and two years postoperatively were significantly lower in those with VTE. Conclusion. The incidence of VTE following ACL reconstruction is 0.4%, and the only significant risk factor is age. Patients with VTE had worse postoperative clinical outcome than patients without VTE. We recommend against the routine use of thromboprophylaxis, but it should be considered in older patients

Reconstruction of the anterior cruciate ligament (ACL) allows to restore stability of the knee, in order to facilitate the return to activity (RTA). Although it is understood that the tendon autograft undergoes a ligamentous transformation postoperatively, knowledge about longitudinal microstructural differences in tissue integrity between types of tendon autografts (ie, hamstring vs. patella) remains limited. Diffusion tensor imaging (DTI) has emerged as an objective biomarker to characterize the ligamentization process of the tendon autograft following surgical reconstruction. One major limitation to its use is the need for a pre-injury baseline MRI to compare recovery of the graft, and inform RTA. Here, we explore the relationship for DTI biomarkers (fractional anisotropy, FA) between knees bilaterally, in healthy participants, with the hypothesis that agreement within a patient's knees may support the use of the contralateral knee as a reference to monitor recovery of the tendon autograft, and inform RTA. Fifteen participants with no previous history of knee injuries were enrolled in this study (age, 26.7 +/− 4.4 years; M/F, 7/8). All images were acquired on a 3T Prisma Siemens scanner using a secured flexible 18-channel coil wrapped around the knee. Both knees were scanned. A 3D anatomical Double Echo Steady State (DESS) sequence was acquired on which regions of interest (ROI) were placed consistent with the footprints of the ACL (femur, posteromedial corner on medial aspect of lateral condyle; tibia, anteromedial to intercondylar eminence). Diffusion images were acquired using fat saturation based on optimized parameters in-house. All diffusion images were pre-processed using the FMRIB FSL toolbox. The footprint ROIs of the ACL were then used to reconstruct the ligament in each patient with fiber-based probabilistic tractography (FBPT), providing a semi-automated approach for segmentation. Average FA was computed for each subject, in both knees, and then correlated against one another using a Pearson correlation to assess the degree of similarity between the ACLs. A total of 30 datasets were collected for this study (1/knee/participant; N=15). The group averaged FA (+/− standard deviation) for the FBPT segmented ACLs were found to equal 0.1683 +/− 0.0235 (dominant leg) and 0.1666 +/− 0.0225 (non-dominant leg). When comparing both knees within subjects, reliable agreement was found for the FBPT-derived ACL with a linear correlation coefficient (rho) equal to 0.87 (P < 0 .001). We sought to assess the degree of concordance in FA between the knees of healthy participants with hopes to provide a method for using the contralateral “healthy” knee in the comparison of autograft-dependent longitudinal changes in microstructural integrity, following ACL reconstruction. Our results suggest that good agreement in anisotropy can be achieved between the non-dominant and dominant knees using DTI and the FBPT segmentation method. Contralateral anisotropy of the ACL, assuming no previous injuries, may be used as a quantitative reference biomarker for monitoring the recovery of the tendon autograft following surgical reconstruction, and gather further insight as to potential differences between chosen autografts. Clinically, this may also serve as an index to supplement decision-making with respect to RTA, and reduce rates of re-injuries

External validation of machine learning predictive models is achieved through evaluation of model performance on different groups of patients than were used for algorithm development. This important step is uncommonly performed, inhibiting clinical translation of newly developed models. Recently, machine learning was used to develop a tool that can quantify revision risk for a patient undergoing primary anterior cruciate ligament (ACL) reconstruction (https://swastvedt.shinyapps.io/calculator_rev/). The source of data included nearly 25,000 patients with primary ACL reconstruction recorded in the Norwegian Knee Ligament Register (NKLR). The result was a well-calibrated tool capable of predicting revision risk one, two, and five years after primary ACL reconstruction with moderate accuracy. The purpose of this study was to determine the external validity of the NKLR model by assessing algorithm performance when applied to patients from the Danish Knee Ligament Registry (DKLR). The primary outcome measure of the NKLR model was probability of revision ACL reconstruction within 1, 2, and/or 5 years. For the index study, 24 total predictor variables in the NKLR were included and the models eliminated variables which did not significantly improve prediction ability - without sacrificing accuracy. The result was a well calibrated algorithm developed using the Cox Lasso model that only required five variables (out of the original 24) for outcome prediction. For this external validation study, all DKLR patients with complete data for the five variables required for NKLR prediction were included. The five variables were: graft choice, femur fixation device, Knee Injury and Osteoarthritis Outcome Score (KOOS) Quality of Life subscale score at surgery, years from injury to surgery, and age at surgery. Predicted revision probabilities were calculated for all DKLR patients. The model performance was assessed using the same metrics as the NKLR study: concordance and calibration. In total, 10,922 DKLR patients were included for analysis. Average follow-up time or time-to-revision was 8.4 (±4.3) years and overall revision rate was 6.9%. Surgical technique trends (i.e., graft choice and fixation devices) and injury characteristics (i.e., concomitant meniscus and cartilage pathology) were dissimilar between registries. The model produced similar concordance when applied to the DKLR population compared to the original NKLR test data (DKLR: 0.68; NKLR: 0.68-0.69). Calibration was poorer for the DKLR population at one and five years post primary surgery but similar to the NKLR at two years. The NKLR machine learning algorithm demonstrated similar performance when applied to patients from the DKLR, suggesting that it is valid for application outside of the initial patient population. This represents the first machine learning model for predicting revision ACL reconstruction that has been externally validated. Clinicians can use this in-clinic calculator to estimate revision risk at a patient specific level when discussing outcome expectations pre-operatively. While encouraging, it should be noted that the performance of the model on patients undergoing ACL reconstruction outside of Scandinavia remains unknown

Background: Anterior cruciate ligament (ACL) injury and re-injury rates are high and continue to rise in adolescents. After surgical reconstruction, less than 50% of patients return to their pre-injury level of physical activity. Clearance for return-to-play and rehabilitation progression typically requires assessment of performance during functional tests. Pain may impact this performance. However, the patient's level of pain is often overlooked during these assessments. Purpose: To investigate the level of pain during functional tests in adolescents with ACL injury. Fifty-nine adolescents with ACL injury (ACLi; female n=43; 15 ± 1 yrs; 167.6 ± 8.4 cm; 67.8 ± 19.9 kg) and sixty-nine uninjured (CON; female n=38; 14 ± 2 yrs; 165.0 ± 10.8 cm; 54.2 ± 11.5 kg) performed a series of functional tests. These tests included: maximum voluntary isometric contraction (MVIC) and isokinetic knee flexion-extension strength tests, single-limb hop tests, double-limb squats, countermovement jumps (CMJ), lunges, drop-vertical jumps (DVJ), and side-cuts. Pain was reported on a 5-point Likert scale, with 1 indicating no pain and 5 indicating extreme pain for the injured limb of the ACLi group and non-dominant limb for the CON group, after completion of each test. Chi-Square test was used to compare groups for the level of pain in each test. Analysis of the level of pain within and between groups was performed using descriptive statistics. The distribution of the level of pain was different between groups for all functional tests (p≤0.008), except for ankle plantar flexion and hip abduction MVICs (Table 1). The percentage of participants reporting pain was higher in the ACLi group in all tests compared to the CON group (Figure 1). Participants most often reported pain during the strength tests involving the knee joint, followed by the hop tests and dynamic tasks, respectively. More specifically, the knee extension MVIC was the test most frequently reported as painful (70% of the ACLi group), followed by the isokinetic knee flexion-extension test, with 65% of ACLi group. In addition, among all hop tests, pain was most often reported during the timed 6m hop (53% of ACLi), and, among all dynamic tasks, during the side-cut (40% of ACLi) test (Figure 1). Furthermore, the tests that led to the higher levels of pain (severe or extreme) were the cross-hop (9.8% of ACLi), CMJ (7.1% of ACLi), and the isokinetic knee flexion-extension test (11.5% of ACLi) (Table 1). Adolescents with and without ACL injury reported different levels of pain for all functional tasks, except for ankle and hip MVICs. The isokinetic knee flexion-extension test resulted in greater rates of severe or extreme pain and was also the test most frequently reported as painful. Functional tests that frequently cause pain or severe level of pain (e.g., timed 6m and cross hops, side-cut, knee flexion/extension MVICs and isokinetic tests) might not be the first test choices to assess function in patients after ACL injury/reconstruction. Reported pain during functional tests should be considered by clinicians and rehabilitation team members when evaluating a patient's readiness to return-to-play. For any figures or tables, please contact the authors directly

Aims. Although knee osteoarthritis (OA) is diagnosed and monitored radiologically, actual full-thickness cartilage loss (FTCL) has rarely been correlated with radiological classification. This study aims to analyze which classification system correlates best with FTCL and to assess their reliability. Methods. A prospective study of 300 consecutive patients undergoing unilateral total knee arthroplasty (TKA) for OA (mean age 69 years (44 to 91; standard deviation (SD) 9.5), 178 (59%) female). Two blinded examiners independently graded preoperative radiographs using five common systems: Kellgren-Lawrence (KL); International Knee Documentation Committee (IKDC); Fairbank; Brandt; and Ahlbäck. Interobserver agreement was assessed using the intraclass correlation coefficient (ICC). Intraoperatively, anterior cruciate ligament (ACL) status and the presence of FTCL in 16 regions of interest were recorded. Radiological classification and FTCL were correlated using the Spearman correlation coefficient. Results. Knees had a mean of 6.8 regions of FTCL (SD 3.1), most common medially. The commonest patterns of FTCL were medial ± patellofemoral (143/300, 48%) and tricompartmental (89/300, 30%). ACL status was associated with pattern of FTCL (p = 0.023). All radiological classification systems demonstrated moderate ICC, but this was highest for the IKDC: whole knee 0.68 (95% confidence interval (CI) 0.60 to 0.74); medial compartment 0.84 (95% CI 0.80 to 0.87); and lateral compartment 0.79 (95% CI 0.73 to 0.83). Correlation with actual FTCL was strongest for Ahlbäck (Spearman rho 0.27 to 0.39) and KL (0.30 to 0.33) systems, although all systems demonstrated medium correlation. The Ahlbäck score was the most discriminating in severe knee OA. Osteophyte presence in the medial compartment had high positive predictive value (PPV) for FTCL, but not in the lateral compartment. Conclusion. The Ahlbäck and KL systems had the highest correlation with confirmed cartilage loss at TKA. However, the IKDC system displayed the best interobserver reliability, with favourable correlation with FTCL in medial and lateral compartments, although it was less discriminating in more severe disease. Cite this article: Bone Joint J 2020;102-B(3):301–309

Aims. Anterior cruciate ligament (ACL) surgery in children and the adolescent population has increased steadily over recent years. We used a national database to look at trends in ACL reconstruction and rates of serious complications, growth disturbance, and revision surgery, over 20 years. Methods. All hospital episodes for patients undergoing ACL reconstruction, under the age of 20 years, between 1 April 1997 and 31 March 2017, were extracted by procedure code from the national Hospital Episode Statistics (HES). Population standardized rates of intervention were determined by age group and year of treatment. Subsequent rates of serious complications including reoperation for infection, growth disturbance (osteotomy, epiphysiodesis), revision reconstruction, and/or contralateral ACL reconstruction rates were determined. Results. Over the 20 year period, 16,125 ACL reconstructions were included. The mean age of patients was 16.9 years (SD 2.0; 27.1% female, n = 4,374/16,125). The majority of procedures were observed in the 15 to 19 years age group. The rate of ACL reconstruction increased 29-fold from 1997 to 1998, to 2016 to 2017. Within 90 days of ACL reconstruction, the rate of reoperation for infection was 0.31% (95% confidence interval (CI) 0.23 to 0.41, n = 50/16,125) and the rate of pulmonary embolism was 0.037% (95%.CI 0.014 to 0.081, n = 6/16,125). Of those with minimum five-year follow-up following ACL reconstruction (n = 7,585), 1.00% of patients subsequently underwent an osteotomy (95% CI 0.79 to 1.25, n = 76/7,585), 0.09% an epiphysiodesis (95% CI 0.04 to 0.19, n = 7/7,585), 7.46% revision ACL reconstruction (95% CI 6.88 to 8.08, n = 566/7,585), and 6.37% contralateral ACL reconstruction (95% CI 5.83 to 6.94, n = 483/7,585). Conclusion. Rates of paediatric and adolescent ACL reconstruction have increased 29-fold over the last 20 years. Despite the increasing rate in the younger population, the risk of serious complications, including further surgery for growth disturbance is very low. The results of our study provide a point of reference for shared decision making in the management of ACL injury in the paediatric and adolescent population. Cite this article: Bone Joint J 2020;102-B(2):239–245

More than 250,000 people are suffering from Anterior Cruciate Ligament (ACL) related injuries each year in the US, with a cost of $17–25K/patient. There is an unmet clinical demand for improving grafts/scaffolds to provide biological integration in addition to mechanical support. Currently, no data is available for the utilization of fibrous scaffolds with bimodal distribution for ACL regeneration. The novelty in this study is that it proposes for the first time to investigate the collagen fibril diameter distribution in healthy and injured bovine ACL tissue, and utilization of such structure for scaffold design. Objectives are 1) developing a bovine ACL tear model and measuring the collagen fibril diameter distribution of both healthy and injured ACL tissues, and 2) fabricating scaffolds to mimic the structural properties of healthy and injured ACL tissue. Bovine ACL tissues (1–3 years old) were harvested and characterized for their fibril diameter distribution using Transmission Electron Microscopy (TEM) and biomechanical properties under tension. The electrospun polycaprolactone (PCL) scaffolds were characterized using SEM and mechanical testing. Healthy and injured ACL fibril diameter, and that of PCL scaffolds representing healthy and injured ACL are compared using unpaired student t-test. The proposed fibrous scaffold design represents a significant departure from the conventional unimodal approach, and is expected to have significant contribution to ACL regeneration. These discoveries will serve as the foundation for the development of biomimetic tissue engineering substrates aimed at promoting biological graft fixation

Revision anterior cruciate ligament (ACL) reconstruction is a technically demanding procedure, reporting poorer outcomes compared to the primary procedure. Identification of the cause of primary failure and a thorough pre-operative evaluation is required to plan the most appropriate surgical approach. 3D printing technology has become increasingly commonplace in the surgical setting. In particular, patient-specific anatomical models can be used to aid pre-operative planning of complicated procedures. We have conducted a qualitative study to gauge the interest amongst orthopaedic knee surgeons in using a 3D-printed model to plan revision ACL reconstructions. A tibia and femur model was printed from one patient who is a candidate for the procedure. The binder jetting printing technique was performed, using Visijet PXL Core powder. 12 orthopaedic knee surgeons assessed the usefulness of the 3D-printed model compared to conventional CT images on a likert scale. 6 key steps of preoperative planning were assessed, including the size and location of the tunnel defects, the need for notchplasty, and whether a staged revision was required. We found that surgeons preferred the 3D-printed model to conventional CT images only, and 83% of them would use such a model for both pre-operative simulation, and as an intra-operative reference. However, there were some variation in the perceived usefulness of the model in several areas assessed. This may reflect differences in individual approach towards planning of the procedure. Our findings suggest that 3D-printed models could be a versatile pre-operative and intra-operative tool for complicated arthroscopic knee surgery. While 3D printing technology is becoming increasingly accessible and affordable, in-depth cost-effectiveness studies need to be conducted before it can be integrated into clinical. Further study would be needed to determine the clinical utility and economic cost-effectiveness of the 3D-printed model in revision ACL reconstruction

Aims. The patient-acceptable symptom state (PASS) is a level of wellbeing, which is measured by the patient. The aim of this study was to determine if the proportion of patients who achieved an acceptable level of function (PASS) after medial unicompartmental knee arthroplasty (UKA) was different based on the status of the anterior cruciate ligament (ACL) at the time of surgery. Methods. A total of 114 patients who underwent UKA for isolated medial osteoarthritis (OA) of the knee were included in the study. Their mean age was 65 years (SD 10). No patient underwent a bilateral procedure. Those who had undergone ACL reconstruction during the previous five years were excluded. The Knee injury Osteoarthritis Outcome Score Activities of Daily Living (KOOS ADL) function score was used as the primary outcome measure with a PASS of 87.5, as described for total knee arthroplasty (TKA). Patients completed all other KOOS subscales, Lysholm score, the Western Ontario and McMaster Universities Osteoarthritis Index, and the Veterans Rand 12-item health survey score. Failure was defined as conversion to TKA. Results. Survivorship at ten years was 97% in both the ACL-deficient and ACL-intact groups. The mean survival was 16.1 years (95% confidence interval (CI) 15.3 to 16.8) for the ACL-deficient group and 15.6 years (95% CI 14.8 to 16.361) for the ACL-intact group (p = 0.878). At a mean of nine years (SD 3.5) in the ACL-deficient group, 32 patients (87%) reached the PASS for the KOOS ADL. In the ACL-intact group, at a mean of 8.6 years (SD 3) follow-up, 63 patients (85%) reached PASS for the KOOS ADL. There was no significant difference in the percentage of patients who reached PASS for all KOOS subscales and Lysholm between the two groups. Conclusion. PASS was achieved in 85% of all UKAs for KOOS ADL, similar to reports for TKA. Fixed-bearing, medial, non-robotically-assisted UKA resulted in 97% survival at ten years in both the ACL-deficient and ACL-intact groups. There was no significant difference in all outcomes between the two groups. Understanding PASS will allow better communication between surgeons and patients to improve the surgical management of patients with single compartment OA of the knee. This study provides mid- to long-term data supporting the use of PASS to document outcomes following UKA. PASS was met in more than 85% of patients with no differences between ACL-deficient and ACL-intact knees at a mean follow-up of nine years. Cite this article: Bone Joint J 2021;103-B(8):1367–1372

Objectives. To compare the effect of femoral bone tunnel configuration on tendon-bone healing in an anterior cruciate ligament (ACL) reconstruction animal model. Methods. Anterior cruciate ligament reconstruction using the plantaris tendon as graft material was performed on both knees of 24 rabbits (48 knees) to mimic ACL reconstruction by two different suspensory fixation devices for graft fixation. For the adjustable fixation device model (Socket group; group S), a 5 mm deep socket was created in the lateral femoral condyle (LFC) of the right knee. For the fixed-loop model (Tunnel group; group T), a femoral tunnel penetrating the LFC was created in the left knee. Animals were sacrificed at four and eight weeks after surgery for histological evaluation and biomechanical testing. Results. Histologically, both groups showed a mixture of direct and indirect healing patterns at four weeks, whereas only indirect healing patterns were observed in both groups at eight weeks. No significant histological differences were seen between the two groups at four and eight weeks in the roof zone (four weeks, S: mean 4.8 . sd. 1.7, T: mean 4.5 . sd. 0.5, p = 0.14; eight weeks, S: mean 5.8 . sd. 0.8, T: mean 4.8 . sd. 1.8, p = 0.88, Mann-Whitney U test) or side zone (four weeks, S: mean 5.0 . sd. 1.2, T: mean 4.8 . sd. 0.4, p = 0.43; eight weeks, S: mean 5.3 . sd. 0.8,T: mean 5.5 . sd. 0.8, p = 0.61, Mann-Whitney U test) . Similarly, no significant difference was seen in the maximum failure load between group S and group T at four (15.6 . sd. 9.0N and 13.1 . sd. 5.6N) or eight weeks (12.6 . sd. 3.6N and 17.1 . sd. 6.4N, respectively). Conclusion. Regardless of bone tunnel configuration, tendon-bone healing after ACL reconstruction primarily occurred through indirect healing. No significant histological or mechanical differences were observed between adjustable and fixed-loop femoral cortical suspension methods. Cite this article: Y. Sato, R. Akagi, Y. Akatsu, Y. Matsuura, S. Takahashi, S. Yamaguchi, T. Enomoto, R. Nakagawa, H. Hoshi, T. Sasaki, S. Kimura, Y. Ogawa, A. Sadamasu, S. Ohtori, T. Sasho. The effect of femoral bone tunnel configuration on tendon-bone healing in an anterior cruciate ligament reconstruction: An animal study. Bone Joint Res 2018;7:327–335. DOI: 10.1302/2046-3758.75.BJR-2017-0238.R2

Introduction and Objective. Osteoarthristis (OA) has been associated with many genes and yet the genetic basis for this disease has never formally been established. Recent realization that epigenetic changes could be the underlying pathological mechanisms has helped to explain many complex multifactorial diseases with no clear genetic cause. We therefore asked whether epigenetics could also play a role in OA. We have previously shown that the DNA epigenetic modification, specifically the hydroxymethylation on cytosine (5hmC), undergoes a fivefold increase on OA-associated genes which are activated at OA onset. In this study, we further uncovered a set of 5hmC-mediated gene targets and their mechanistic link to OA progression. Materials and Methods. We surgically induced OA on 4 to 6 months old Tet1−/− mice (Tet1tm1.1Jae, the Jackson laboratory) and wild-type littermates by performing destabilization of the medial meniscus (DMM) surgery. Joints were collected for histological assessment through blinded grading with the OARSI scoring system. Human articular chondrocytes were harvested from OA cartilage samples obtained during total knee arthroplasty or from grossly normal cartilage pieces obtained during notchplasty or debridement from patients undergoing anterior cruciate ligament (ACL) reconstruction with no history of OA symptoms, under approved Human subjects Institutional Review Board protocols. Bioinformatic analyses of RNA-sequencing and CCGG sequencing (reduced representation 5hmC profiling) were performed to identify TET1 target genes associated with OA progression. Several measurements were used to assess the effect of TET1 ablation on the phenotype of mouse cartilage tissue and human chondrocytes including, histological evaluation, and quantitative bone assessment by micro-CT imaging and multiplex cytokine analyses in the serum of mice in vivo (mouse 39-plex assay) and in the supernatant of human chondrocyte cultures (human 62-plex assay). Results. We used a mouse model with surgically induced OA and found that OA onset was accompanied by a gain of ∼40,000 differentially hydroxymethylated sites prior the notable histological onset of the disease. We additionally revealed that these changes are mediated by the ten-eleven-translocation enzyme 1 (TET1), since Tet1−/− mice lost 98% of 5hmC sites upon OA induction. Remarkably, Tet1−/− mice were protected from OA development including degeneration of the cartilage surface and osteophyte formation. Silencing of TET1 expression in human OA chondrocytes reduced the expression in a set of genes, which may represent the pathological gene targets that exacerbate OA including MMP3 and MMP13 and several inflammatory cytokines. Therefore, our study reveals the unexpected beneficial role of TET1 inhibition in blocking OA progression. In fact, intra-articular injections of a dioxygenases’ inhibitor, 2 hydroxyglutarate, on mice after surgical induction of OA stalled disease progression. Furthermore, treatment of human OA chondrocytes with the same inhibitor also phenocopied TET1 loss, implicating a therapeutic potential of TET inhibition in OA patients. Conclusions. Collectively, our study not only demonstrate the role of TET1 in OA; the 5hmC-mediated gene targets acting on multiple OA pathways were identified and can be modulated as therapeutic intervention to treat OA

The June 2015 Knee Roundup360 looks at: Cruciate substituting versus retaining knee replacement; What’s behind the psychology of anterior cruciate ligament (ACL) reconstruction?; Is there a difference in total knee arthroplasty risk of revision in highly crosslinked versus conventional polyethylene?; Unicompartmental knee arthroplasty: is age the missing variable?; Satisfaction rates following total knee arthroplasty; Is knee alignment dynamic?; Unicompartmental knee arthroplasty: cemented or cementless?; Can revision knee services pay?

Recent findings have identified the importance of previously undiagnosed or neglected meniscus lesions in association with anterior cruciate ligament (ACL) injuries (e.g. medial meniscus ramp lesions and posterior root tears of the lateral meniscus). There is increasing biomechanical evidence that they bear the potential to alter both anteroposterior and rotational laxity patterns in ACL injured knees. Few data exist with respect to the presence of these specific tear entities in large series of ACL injured patients. The purpose of the study was to analyze the meniscus tear pattern in a series of ACL injured knees with a special focus on ramp lesions of the medial meniscus and posterior root lesions of the lateral meniscus. The hypothesis was that a significant number of ACL injured patients would display these types of lesions. Data from 358 patients undergoing an ACL reconstruction (227 males /131 females, age: 28±10) were extracted from a center-based registry. The type of ACL tear (partial versus complete) as well as the presence of associated meniscus lesions were documented. Meniscus lesions were classified into the following categories: medial ramp lesions, lateral root lesions, medial ramp and lateral root lesion, other medial meniscus injuries, other lateral meniscus injuries, other bimeniscal injuries. Chi-square tests were used to determine whether the percentage of meniscal lesions differed between types of ACL tear, gender and age (below 21, 21–35, above 35). Significance was set at p < 0.05. Isolated ACL tears were present in 107 (30%) of the operated knees (31 partial; 327 complete). Complete ACL lesions were more likely to present an associated meniscus injury (321 out of 327, 71%) than partial tears (13 out of 31, 42%). The incidence of meniscus injuries which are associated with ACL tears is very high (70%). Previously undiagnosed or neglected meniscus injuries like medial ramp or lateral root tears could be identified in 35% of patients. As such, the hypothesis was confirmed that an important amount of ACL injured knees display this specific intraarticular soft tissue damage. A systematic evaluation of these lesions under arthroscopy should thus be performed and specific repair needs to be evaluated

The fibrocartilaginous enthesis displays a complex interface between two mechanically dissimilar tissues, namely tendon and bone. This graded transition zone consists of parallel collagen type I fibres arising from the tendon and inserting into bone across zones of fibrocartilage with aligned collagen type I and collagen type II fibres and mineralised fibrocartilage. Due the high stress concentrations arising at the interface, entheses are prone to traumatic and chronic overuse injuries such as rotator cuff and anterior cruciate ligament (ACL) tears. Treatment strategies range from surgical reattachment for complete tears and conservative treatments (physiotherapy, anti-inflammatory drugs) in chronic inflammatory conditions. Generally, the native tissue architecture is not re-established and mechanically inferior scar tissue is formed. Current interfacial tissue engineering approaches pose scaffold-associated drawbacks and limitations, such as foreign body response. Using a thermo-responsive electrospun scaffold that provides architectural signals similar to native tissues and can be removed prior to implantation, we aim to develop an ECM-rich, cell-based implant for tendon-enthesis regeneration. Alcian blue staining revealed highest sGAG deposition in cell (human adipose derived stem cells) sheets grown on random electrospun fibres and lowest sGAG deposition in collagen type I sponges. Cells did not show an equal distribution throughout the collagen type II scaffolds but tended to form localised aggregates. Thermo-responsive electrospun fibres with random and aligned fibre orientation provided an adequate three-dimensional environment for chondrogenic differentiation of multilayer hADSC-sheets shown by high ECM-production, especially high sGAG deposition. Chondrogenic cell sheets showed increased expression of SOX9, COL2A1, COL1A1, COMP and ACAN after 7 days of chondrogenic induction when compared to pellet culture. Anisotropic fibres enabled the generation of aligned chondrogenic cell sheets, shown by cell and collagen fibre alignment. Thermoresponsive electrospun fibres showed high chondro-inductivity due to their three-dimensionality and therefore pose a promising tool for the generation of scaffold-free multilayer constructs for tendon-enthesis repair within short culture periods. Aligned chondrogenic cell sheets mimic the zonal orientation of the native enthesis as the fibrocartilaginous zone exhibits high collagen alignment

Between 1993 and 1994, 891 patients underwent primary anterior cruciate ligament (ACL) reconstruction. A total of 48 patients had undergone bilateral ACL reconstruction and 42 were available for review. These patients were matched to a unilateral ACL reconstruction control group for gender, age, sport of primary injury, meniscal status and graft type. At 15-year follow-up a telephone interview with patients in both groups was performed. The incidence of further ACL injury was identified through structured questions and the two groups were compared for the variables of graft rupture or further ACL injury, family history of ACL injury, International Knee Documentation Committee (IKDC) subjective score and activity level. There were 28 male and 14 female patients with a mean age of 25 years (13 to 42) at the time of first ACL injury. Subsequent further ACL injury was identified in ten patients (24%) in the bilateral ACL reconstruction study group and in nine patients (21%) in the unilateral ACL reconstruction control group (p = 0.794). The mean time from bilateral ACL reconstruction to further ACL injury was 54 months (6 to 103). There was no significant difference between the bilateral ACL reconstruction study group and the matched unilateral ACL reconstruction control group in incidence of further ACL injury (p = 0.794), family history of ACL injury (p = 0.595), IKDC activity level (p = 0.514), or IKDC subjective score (p = 0.824). After bilateral ACL reconstruction the incidence of graft rupture and subjective outcomes were equivalent to that after unilateral ACL reconstructions. Cite this article: Bone Joint J 2013;95-B:798–802

Objectives. The injured anterior cruciate ligament (ACL) is thought to exhibit an impaired healing response, and attempts at surgical repair have not been successful. Connective tissue growth factor (CTGF) is reported to be associated with wound healing, probably through transforming growth factor beta 1 (TGF-β1). Methods. A rabbit ACL injury model was used to study the effect of CTGF on ligament recovery. Quantitative real-time PCR (qRT-PCR) was performed for detection of changes in RNA levels of TGF-β1, type 1 collagen (COL1), type 2 collagen (COL2), SRY-related high mobility group-box gene9 (SOX9), tissue inhibitor of metalloproteinase-1 (TIMP-1) and matrix metallopeptidase 13 (MMP-13). Expression of related proteins was detected by Western blotting. Results. The current study showed that CTGF could promote the recovery of an injured anterior cruciate ligament. It can upregulate mRNA and expression of TGF-β1, COL1, COL2, SOX9, and tissue inhibitor of TIMP-1, and downregulate mRNA and expression of MMP-13, suggesting that the curative effect of CTGF on injured rabbit ligaments is through regulation of these cellular factors. Conclusions. This finding revealed the healing role of CTGF in injured tissues and provides new possibilities of treating injured tissues and wound healing by using CTGF. Cite this article: X. Sun, W. Liu, G. Cheng, X. Qu, H. Bi, Z. Cao, Q. Yu. The influence of connective tissue growth factor on rabbit ligament injury repair. Bone Joint Res 2017;6:399–404. DOI: 10.1302/2046-3758.67.BJR.2016-0255.R1

Aims. Different methods of anterior cruciate ligament (ACL) reconstruction have been described for skeletally immature patients before closure of the growth plates. However, the outcome and complications following this treatment remain unclear. The aim of this systematic review was to analyse the outcome and complications of different techniques which may be used for reconstruction of the ACL in these patients. Materials and Methods. We performed a systematic review of the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. This involved a comprehensive search of PubMed, Medline, CINAHL, Cochrane, Embase and Google Scholar databases using the following combinations of keywords, “knee”, “anterior cruciate ligament”, “reconstruction”, “injury”, “children”, “adolescent”, “skeletally immature”, “open physis” and “surgery”. Results. A total of 53 studies met the inclusion criteria and were included for analysis. The overall rate of disturbance of growth after ACL reconstruction was 2.6%, with no statistical difference between transphyseal and physeal-sparing techniques. Physeal-sparing techniques had a lower rate of post-operative complications compared with transphyseal techniques (p = 0.0045). Outcomes assessed were Lysholm score, International Knee Documentation Committee (IKDC) score, the IKDC grade, the Tegner score and the KT-1000. Both techniques had similar clinical outcomes. Conclusions. This review reveals low rates of disturbance of growth after ACL reconstruction in skeletally immature patients. Although limited, the available evidence did not support any particular surgical technique when considering disturbance of growth or clinical outcome. Further randomised controlled trials are needed to investigate the efficacy of differing surgical techniques on outcomes in skeletally immature patients. Cite this article: Bone Joint J 2017;99-B:1053–60

There have been mixed reports of the contribution of the anterior cruciate ligament (ACL) to the overall envelope of tibial rotational stability. The effect of single bundle ACL reconstruction on the separate components of internal and external rotational stability respectively is also unclear. We determined the internal and external rotation, and antero-posterior movement of the knee before and after single bundle computer assisted reconstruction of the anterior cruciate ligament (ACL) in 57 patients. The Orthopilot. ®. ACL (v2) software (BBraun, Aesculap) was used. The mean overall range of tibial rotation was also significantly reduced from 30.5 degrees to 16 degrees (p< 0.0001). The mean internal rotation was significantly reduced from 16 degrees to 8 degrees (p< 0.0001). Mean external rotation was also significantly reduced from 15 degrees to 8 degrees (p< 0.0001). Unlike previous studies we did not find a greater reduction of internal rotation compared with external rotation. The mean antero-posterior movement of the tibia was significantly reduced from 12mm to 4mm (p< 0.0001). The results of this study seem to indicate that computer assisted single bundle ACL reconstruction results in a significant intraoperative improvement in both internal and external rotatory stability as well as a significant improvement in antero-posterior stability

After anterior cruciate ligament (ACL) rupture, reconstructive surgery with a hamstring tendon autograft is often performed. Despite overall good results, ACL re-rupture occurs in up to 10% of the patient population, increasing to 30% of the cases for patients aged under 20 years. This can be related to tissue remodelling in the first months to years after surgery, which compromises the graft's mechanical strength. Resident graft fibroblasts secrete matrix metalloproteinases (MMPs), which break down the collagen I extracellular matrix. After necrosis of these fibroblasts, myofibroblasts repopulate the graft, and deposit more collagen III rather than collagen I. Eventually, the cellular and matrix properties converge towards those of the native ACL, but full restoration of the ACL properties is not achieved. It is unknown how inter-patient differences in tissue remodelling capacity contribute to ACL graft rupture risk. This research measured patient-specific tissue remodelling-related properties of human hamstring tendon-derived cells in an in vitro micro-tissue platform, in order to identify potential biological predictors for graft rupture. Human hamstring tendon-derived cells were obtained from remnant autograft tissue after ACL reconstructions. These cells were seeded in collagen I gels on a micro-tissue platform to assess inter-patient cellular differences in tissue remodelling capacity. Remodelling was induced by removing the outermost micro-posts, and micro-tissue compaction over time was assessed using transmitted light microscopy. Protein expression of tendon marker tenomodulin and myofibroblast marker α-smooth muscle actin (αSMA) were measured using Western blot. Expression and activity of remodelling marker MMP2 were determined using gelatin zymography. Cells were obtained from 12 patients (aged 12–51 years). Patient-specific variations in micro-tissue compaction speed or magnitude were observed. Up to 50-fold differences in αSMA expression were found between patients, although these did not correlate with faster or stronger compaction. Surprisingly, tenomodulin was only detected in samples obtained from two patients. Total MMP2 expression varied between patients, but no large differences in active fractions were found. No correlation of patient age with any of the remodelling-related factors was detected. Remodelling-related biological differences between patient tendon-derived cells could be assessed with the presented micro-tissue platform, and did not correlate with age. This demonstrates the need to compare this biological variation in vitro - especially cells with extreme properties - to clinical outcome. Sample size is currently increased, and patient outcome will be determined. Combined with results obtained from the in vitro platform, this could lead to a predictive tool to identify patients at risk for graft rupture

Ligament fibroblasts must be mechanosensitive and possess sufficient adaptability to a novel mechanomilieu ensuring the permanent load capacity of the tissue. Once mechanoreceptors are activated, the fibroblasts react with a specific signal transmission (mechanotransduction), which ultimately leads to an adaption of their cytoskeletal organization and protein synthesis. However, the cellular response of anterior cruciate ligament (ACL) fibroblasts to cyclic mechanical stretching is still unclear. Hence, this study should allow a deeper understanding of the reaction profile of mechanically stretched ACL cells in two- (2D) and three-dimensional (3D) biomaterial-free and biomaterial cultures with respect to cell survival, size, orientation, migration and distribution. For the 2D approach consisting of monolayers with 6000 lapine (L) ACL cells per cm2 and for the 3D cultures using preformed LACL cell spheroids (2.5–4/cm2) with 25.000 cells per spheroid, silicone chambers were coated with geltrex and statically colonized with the LACL cells for 24 h before cyclically stretched for 48 h (14 percent uniaxial stretch). A second approach using 3D scaffold cultures was performed which were seeded dynamically for 24 h with LACL cells before cyclically stretched in a novel custom-made mechanostimulator. The scaffolds [polylactic acid (PLA) and polycaprolactone (PCL)] were functionalized with 10 percent gas fluorination and a collagen foam. Scaffolds (120 mm2) were precolonized dynamically with an LACL cell suspension (1 mio cells/mL) for 24 h before stretched for 72 h (4 percent uniaxial stretch). Cell vitality and numbers were monitored. The cytoskeleton orientation was shown by cytochemistry (F-actin) and evaluated (ImageJ). Cell proliferation, based on the DNA content was measured. Cell viability in stretched samples (2D, 3D and scaffold) remained above 90 percent. Stretching on the silicone chambers led to increased cell counts, length and significantly higher colonized areas than in unstretched controls. Higher numbers of LACL cells migrated out of the 3D spheroids under stretching conditions. In response to intermittent stretching, cells oriented in a 70 degrees' angle against the stretch direction in silicone chambers, whereas cell arrangement was more compact on the threads of the scaffolds than in unstretched cultures. In summary, stretching induced a rapid (48 h) cell and cytoskeletal alignment in 2D as well as in 3D cultures. The natural ACL is characterized by a strongly uniaxial cell and extracellular matrix organization which might be achieved in tissue engineered constructs by a suitable cyclic stretching protocol in future

Aims. The aim of this study was to investigate the long-term clinical and radiological outcome of patients who suffer recurrent injuries to the anterior cruciate ligament (ACL) after reconstruction and require revision surgery. Patients and Methods. From a consecutive series of 200 patients who underwent primary reconstruction following rupture of the ACL, we identified 36 who sustained a further rupture, 29 of whom underwent revision surgery. Patients were reviewed prospectively at one, two, seven, 15 and about 20 years after their original surgery. Primary outcome measures were the number of further ruptures, the posterior tibial slope (PTS), and functional and radiological outcomes. These were compared with a gender and age matched cohort of patients who underwent primary ACL reconstruction only. Results. At a mean follow-up of 18.3 years (14.3 to 20.2), 29 patients had undergone revision surgery and within this revision group 11 had sustained more than three ruptures of the ACL (3 to 6). The mean age at the time of revision reconstruction was 26.4 years (14 to 54). The mean PTS was significantly higher in those patients who suffered a further injury to the ACL (11°) compared with the control group (9°) (p < 0.001). The mean PTS in those patients who sustained more than three ruptures was 12°. Conclusion. Patients who suffer recurrent injuries to the ACL after reconstruction have poorer functional and radiological outcomes than those who suffer a single injury. The causes of further injury are likely to be multifactorial but an increased PTS appears to have a significant association with recurrent ACL injuries. Cite this article: Bone Joint J 2017;99-B:337–43

Introduction. A bicruciate retaining (BCR) TKA is thought to maintain a closer resemblance to the native knee kinematics compared to a posterior cruciate retaining (CR) TKA. With BCR TKAs retainment of the anterior cruciate ligament (ACL) facilitates proprioception and balance which is thought to lead to more natural knee kinematics and increased functional outcome. The aim of this study was to quantify and compare the kinematics of a BCR and CR TKA during functional tests. Materials and Methods. In this patient-blinded randomized controlled trial, a total of 40 patients with knee osteoarthritis were included, 18 of them received a BCR TKA (Vanguard XP, Zimmer-Biomet) and 22 received a CR TKA (Vanguard CR, Zimmer-Biomet). Fluoroscopic analysis was done 1 year post-operatively. The main outcome was posterior femoral rollback (i.e. translation of the femorotibial contact point (CP)) of the BCR and CR TKA during a step-up test. Secondary, the kinematics during a lunge test were quantified as anterior-posterior (AP) translation of the femorotibial CP. Independent student t-tests (or non-parametric equivalent) were used to analyze the effect of BCR versus CR TKA on these measures, to correct for the multiple testing problem post-hoc Bonferroni-Holm corrections were applied. Results. The mean AP CP for the BCR implant was not significantly different from the CR implant in the medial compartment (Figure 1, left). However, laterally the BCR implant shows a more posterior CP during late extension i.e. from 30° flexion to 0° extension (Figure 1, right). Figure 2 shows the AP CP during the final extension phase (30° flexion to 0° extension) of the step-up task for both implants on the tibia plateau. While the CR TKA remains mostly stable throughout this phase, the BCR TKA shows tibial internal rotation from 30° to 10° and tibial external rotation in the final extension phase: a kinematic pattern comparable to the natural knee's screw home mechanism. The lateral AP CP of the BCR TKA is more posterior compared to the CR TKA during the whole lunge task (Figure 3, right) the medial CP is more anterior in the 0–30° flexion (Figure 3, left). The main differences between the implants during the lunge task are observable in the early flexion phase, which is in line with ACL function. Conclusion. These preliminary results suggest that the kinematics of the BCR implant reproduces the natural screw-home mechanism in early flexion/late extension. The difference between the BCR and CR implants is mostly visible in the flexion phase in which the ACL is effective, which is in congruency with the absence of the ACL in CR TKAs. For any figures or tables, please contact the authors directly

Introduction. Simultaneous correction of knee varus malalignment with medial open wedge high tibial osteotomy (MOWHTO) combined with anterior cruciate ligament (ACL) surgery aims to address symptomatic unicompartmental osteoarthritis in addition to restore knee stability in order to improve outcomes. The aim of this study is to present at least 5 years results of 32 patients who underwent simultaneous knee realignment osteotomy with ACL surgery. Methods. Patients with symptomatic instability due to chronic ACL deficiency or failed previous ACL surgery together with a varus malalignment of ≥6°, previous medial meniscectomy and symptomatic medial compartment pain who were treated with MOWHTO combined with ACL surgery were enrolled. ACL surgery was performed with the anatomical single bundle all-inside technique using TightRope. ®. RT (Arthrex, Naples, FL, USA) and MOWHTO using TomoFix. ®. medial high tibia plate (DePuy Synthes, Raynham, MA, USA) in all cases. Patients were evaluated preoperatively and at 6 months, 12 months and annually postoperatively using the Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS) and Euroqol's Visual Analogue Score (VAS) for pain. Results. 32 patients (22 men and 10 women) with a mean age of 41.2 years and mean BMI of 28.6 kg/m. 2. , underwent the combined procedures. Tibiofemoral neutral re-alignment was achieved in all patients with HTO. Complete subjective and objective scores have been obtained in 84.4% of patients with at least 5 years of follow-up (mean 8.7 years). An improvement in total KOOS of 27.1 points (p<0.003), OKS of 15.1 (p<0.003) and VAS for pain of 24.7 points (p<0.001) were detected. No ACL reconstruction failure was noted. Complications consisted of one superficial wound infection and one delayed union. Plate removal was needed in 20 (62.5%) patients due to pes anserinus pain. Conclusions. Simultaneous restoration of coronal knee axis by applying HTO and stability by ACL reconstruction/revision were reported to offer excellent improvement in early outcomes in patients with ACL rupture and symptomatic unicompartmental osteoarthritis. The combined procedure requires careful pre-operative planning and is therefore technically challenging. However, by restoring the neutral axis and providing stability, it represents a good joint preserving alternative to arthroplasty for active middle-aged patients

Due to unsatisfactory results and reported drawbacks of anterior cruciate ligament (ACL) reconstruction new regenerative approaches based on tissue-engineering strategies are currently under investigation. It was the purpose of this study to determine if a novel silk fiber-based ACL scaffold is able to initiate osteointegration in the femoral and tibial bone tunnels under in vivo conditions. Furthermore we tested if the osteointegration process will be improved by intraoperatively seeding the scaffolds with the autologous stromal vascular fraction, an adipose-derived, stem cell-rich isolate from knee fat pads. In this controlled laboratory study, 33 sheep underwent ACL resection and were then randomly assigned to 2 experimental groups: ACL reconstruction with a scaffold alone and ACL reconstruction with a cell-seeded scaffold. Half of the sheep in each group were randomly chosen and euthanized 6 months after surgery and the other half at 12 months. To analyze the integration of the silk-based scaffold in the femoral and tibial bone tunnels, hard tissue histology and micro-computed tomography measurements were performed. The histological workup showed that in all treatment groups, with or without the application of the autologous stromal vascular fraction, an interzone of collagen fibers had formed between bone and silk-based graft. This collagen-fiber continuity partly consisted of Sharpey fibers, comparable with tendon-bone healing known for autografts and allografts. Insertion sites were more broad based at 6 months and more concentrated on the slightly protruding, bony knoblike structures at 12 months. Histologically, no differences between the treatment groups were detectable. Analysis of micro-computed tomography measurements revealed a significantly higher tissue density for the cell-seeded scaffold group as compared with the scaffold-alone group in the tibial but not femoral bone tunnel after 12 months of implantation. The novel silk fiber-based scaffold for ACL regeneration demonstrated integration into the bone tunnels via the formation of a fibrous interzone similar to allografts and autografts. Histologically, additional cell seeding did not enhance osteointegration. No significant differences between 6 and 12 months could be detected. After 12 months, there was still a considerable amount of silk present, and a longer observation period is necessary to see if a true ligament-bone enthesis will be formed

To describe our experience with computer assisted combined anterior cruciate ligament (ACL) reconstruction and osteotomy. It may provide long-term symptom relief and improved function in patients with medial knee arthrosis and ACL-deficiency, while delaying or possibly eliminating the need for further surgical intervention such as arthroplasty. Two patients who had medial unicompartmental arthrosis and chronic ACL-deficient knees underwent ACL reconstruction along with femoral osteotomy in one case and upper tibial osteotomy in the other. We used Orthopilot software to perform computer assisted combined anterior cruciate ligament (ACL) reconstruction and osteotomy. Subjective evaluation at postoperatively indicated significant improvement compared to preoperative evaluation and better scores for patients who obtained normal knee range of motion. Objective evaluation by International Knee Documentation Committee showed improved score postoperatively. Both had minor complications occurred in the immediate postoperative period. The average correction angle of the osteotomy was 7 degrees (7–10). Computer assisted ACL reconstruction and osteotomy may provide long-term symptomatic pain relief, increased activity and improved function. Only Anterior cruciate ligament reconstruction may not effectively provide pain relief to the ACL-deficient knee with degenerative medial arthrosis. The results of this study suggest that combined high tibial or femoral osteotomy and ACL reconstructions are effective in the surgical treatment of varus, ACL-deficient knees with symptomatic medial compartment arthritis. Computer aided surgery allows precise correction of the axial deformity and tunnel orientation intraoperatively

Objectives. This study aimed to investigate time-dependent gene expression of injured human anterior cruciate ligament (ACL), and to evaluate the histological changes of the ACL remnant in terms of cellular characterisation. Methods. Injured human ACL tissues were harvested from 105 patients undergoing primary ACL reconstruction and divided into four phases based on the period from injury to surgery. Phase I was < three weeks, phase II was three to eight weeks, phase III was eight to 20 weeks, and phase IV was ≥ 21 weeks. Gene expressions of these tissues were analysed in each phase by quantitative real-time polymerase chain reaction using selected markers (collagen types 1 and 3, biglycan, decorin, α-smooth muscle actin, IL-6, TGF-β1, MMP-1, MMP-2 and TIMP-1). Immunohistochemical staining was also performed using primary antibodies against CD68, CD55, Stat3 and phosphorylated-Stat3 (P-Stat3). . Results. Expression of IL-6 was mainly seen in phases I, II and III, collagen type 1 in phase II, MMP-1, 2 in phase III, and decorin, TGF-β1 and α-smooth muscle actin in phase IV. Histologically, degradation and scar formation were seen in the ACL remnant after phase III. The numbers of CD55 and P-Stat3 positive cells were elevated from phase II to phase III. . Conclusions. Elevated cell numbers including P-Stat3 positive cells were not related to collagens but to MMPs’ expressions