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

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.

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.

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.

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 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. Patient dissatisfaction following primary total knee arthroplasty (TKA) with manual jig-based instruments has been reported to be as high as 30%. Robotic-assisted total knee arthroplasty (RA-TKA) has been increasingly used in an effort to improve patient outcomes, however there is a paucity of literature examining patient satisfaction after RA-TKA. This study aims to identify the incidence of patients who were not satisfied following RA-TKA and to determine factors associated with higher levels of dissatisfaction. Methods. This was a retrospective review of 674 patients who underwent primary TKA between October 2016 and September 2020 with a minimum two-year follow-up. A five-point Likert satisfaction score was used to place patients into two groups: Group A were those who were very dissatisfied, dissatisfied, or neutral (Likert score 1 to 3) and Group B were those who were satisfied or very satisfied (Likert score 4 to 5). Patient demographic data, as well as preoperative and postoperative patient-reported outcome measures, were compared between groups. Results. Overall, 45 patients (6.7%) were in Group A and 629 (93.3%) were in Group B. Group A (vs Group B) had a higher proportion of male sex (p = 0.008), preoperative chronic opioid use (p < 0.001), preoperative psychotropic medication use (p = 0.01), prior anterior cruciate ligament (ACL) reconstruction (p < 0.001), and preoperative symptomatic lumbar spine disease (p = 0.004). Group A was also younger (p = 0.023). Multivariate analysis revealed preoperative opioid use (p = 0.012), prior ACL reconstruction (p = 0.038), male sex (p = 0.006), and preoperative psychotropic medication use (p = 0.001) as independent predictive factors of patient dissatisfaction. Conclusion. The use of RA-TKA demonstrated a high rate of patient satisfaction (629 of 674, 93.3%). Demographics for patients not satisfied following RA-TKA included: male sex, chronic opioid use, chronic psychotropic medication use, and prior ACL reconstruction. Patients in these groups should be identified preoperatively and educated on realistic expectations given their comorbid conditions. Cite this article: Bone Jt Open 2024;5(9):758–765

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.

Aims

There is limited information on outcomes of revision ACL reconstruction (rACLR) in soccer (association football) athletes, particularly on return to sport and the rate of additional knee surgery. The purpose of this study was to report return to soccer after rACLR, and to test the hypothesis that patient sex and graft choice are associated with return to play and the likelihood of future knee surgery in soccer players undergoing rACLR.

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.

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

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

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 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

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