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Purpose: Badminton requires fast and pivoting movements, putting athletes at risk of sustaining an anterior cruciate ligament (ACL) injury. The primary purpose is to investigate the return to sport (RTS) and the return to performance (RTP) after an ACL injury in elite badminton athletes. The secondary purpose is to describe ACL injury mechanisms in elite badminton players., Methods: Athletes within the top 200 of the Badminton World Federation World Ranking who sustained an ACL injury between January 2001 and December 2021 were retrospectively included. An anonymous online survey was created in eight languages. RTS, RTP and contributing factors were analysed among athletes aiming to RTP. The injury mechanism was analysed in all participants., Results: Sixty-six athletes from 32 countries were included. Fifty-seven athletes (86.4%) aimed to RTP. Forty-eight out of 57 (84.2%) did RTS. Twenty-nine (50.9%) managed to successfully RTP. Forty-nine (74.2%) of ACL injuries occurred during a competition, 14 (21.2%) occured during training. Thirty-one (49.2%) occurred in the rear court backhand side and 47 (74.6%) occurred during landing after a jump., Conclusion: Forty-eight out of 57 (84.2%) athletes managed to RTS. Half of the athletes managed to successfully RTP. Most of the ACL injuries occurred during competition, in the rear court backhand side and during landing after a jump., Level of Evidence: Level III., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Purpose: To analyse anterior cruciate ligament (ACL) rupture (ACLR) injury mechanisms in competitive judo using systematic video analysis, focusing on contact situations and biomechanics., Methods: Seventeen videos of judo competitions wherein athletes developed ACLRs were included and retrospectively evaluated by five analysts. In all videos, the moment of initial contact and the index frame were defined. The judo techniques leading to the injury; the occurrence of direct contact, indirect contact or noncontact mechanisms; the time interval between the initial contact and index frame; the positions of the hip, knee and foot in relation to the initial contact and index frame; and the balance status during the initial contact and index frame were recorded., Results: Eleven (65%) of ACLRs in judo involved direct contact. The mean time interval between initial contact and index frame was 15 ± 22 ms. Thirteen (77%) athletes were not balanced at initial contact. In the index frame, the hip was abducted in all cases and in combination with internal rotation in 12 (71%) cases. From initial contact to index frame, hip flexion increased in all cases; at index frame, the knee joint was internally rotated relative to the trunk in 12 (71%) cases, and the knee flexion angles increased from the initial contact. In the index frame, the foot was externally rotated relative to the knee in 12 (71%) cases, and severe valgus development of the knee with valgus collapse was observed in 14 (82%) cases., Conclusions: A direct attack on the knee was the most common injury mechanism observed. Valgus distortion appears to be the most important component of the mechanism of injury. With this knowledge, 'modified defence reactions' for specific judo techniques can be developed to reduce the injury risk., Level of Evidence: Level IV., (© 2024 The Author(s). Knee Surgery, Sports Traumatology, Arthroscopy published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Purpose: Virtual reality-based therapy (VRBT) may be an effective physical therapy complement employed in the rehabilitation of patients with anterior cruciate ligament (ACL) injury. This study aims to assess the effectiveness of VRBT in improving pain, knee function, strength, proprioception, flexion range of motion (ROM), and dynamic balance after ACL injury., Methods: We conducted this systematic review with meta-analysis following PRISMA criteria. Since inception to June 2024, we searched in PubMed Medline, WOS, SCOPUS, CINAHL and PEDro without publication date and language restrictions. Randomised controlled trials (RCTs), comprising only patients with ACL injury, that assess the effectiveness of VRBT compared to classical interventions on the outcomes of interest were included. PEDro scale was employed to analyze the methodological quality of the RCTs included. Cohen's standardised mean difference (SMD) and its 95% confidence interval (95% CI) was used to calculate the pooled effect in meta-analyses., Results: Nine RCTs, providing data from 330 participants (26.96 ± 3.11 years, 85% males) were included. The RCTs included showed good methodological quality (PEDro scale = 6.88 points), being, performance and detection biases, the most common biases reported. Meta-analyses showed that VRBT was more effective than classical interventions in reducing pain (SMD = -1.15; 95% CI -1.85 to -0.45; p = 0.001; I 2  = 0%), and increasing knee function (SMD = 1.71; 95% CI 0.93 to 2.5; p < 0.001; I 2  = 0%), strength (SMD = 0.82; 95% CI 0.4-1.23; p < 0.001; I 2  = 0%) and flexion ROM (SMD = 0.7; 95% CI 0.37-1.01; p < 0.001; I 2  = 0%). Additionally, VRBT improved postero-medial (SMD = 0.46; 95% CI 0.01-0.9; p = 0.045; I 2  = 15.1%) and postero-lateral CoP excursion (SMD = 0.75; 95% CI 0.3-1.21; p = 0.001; I 2  = 0%), being effective in improving dynamic balance., Conclusion: VRBT is an effective physical therapy complement to be included in the ACL's rehabilitation programmes due to reduces pain and increases knee function, strength, ROM and dynamic balance after ACL injury., Level of Evidence: Level II evidence., (© 2024 The Author(s). Knee Surgery, Sports Traumatology, Arthroscopy published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Purpose: In adolescent patients, meniscal tear injury can occur either in isolation (e.g., discoid lateral meniscus tears) or in association with other traumatic injuries including tibial eminence fracture or ACL tear. Damage to meniscal integrity has been shown to increase contact pressure in articular cartilage, increasing risk of early onset osteoarthritis. In symptomatic patients failing conservative management, surgical intervention via meniscus repair or meniscus transplant is indicated. The purpose of this study was to evaluate the radial dimensions of pediatric menisci throughout development. The hypothesis was that the average radial meniscus dimensions will increase as specimen age increases, and mean medial and lateral region measurements will increase at a linear rate., Methods: Seventy-eight skeletally immature knee cadaver specimens under age 12 years were included in this study. The meniscal specimens were photographed in the axial view with ruler in the plane of the tibial plateau and analyzed using computer-aided design (CAD) software (Autodesk Fusion 360). Measurements were taken from inner to outer meniscus rims at five 45 degree intervals using the clockface as a reference (12:00, 1:30, 3:00, 4:30, 6:00), and total area of meniscus and tibial plateau was recorded. Generalized linear models were used to evaluate the associations of radial width measurements with age, tibial coverage, and lateral vs. medial meniscus widths., Results: All radial width measurements increased significantly with specimen age (p ≤ 0.002), and all lateral-medial meniscal widths increased (p < 0.001). The anterior zones of the meniscus were found to increase at the slowest rate compared to other regions. Tibial plateau coverage was found to not significantly vary with age., Conclusions: Meniscus radial width and lateral-medial meniscus width are related to age. The anterior width of the meniscus varied least with age. Improved anatomic understanding may help surgeons more effectively plan for meniscus repair, discoid resection/saucerization/repair, and also support appropriate selection of meniscus allograft for transplantation., (© 2023. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: To determine potential quadriceps versus hamstring tendon autograft differences in neuromuscular function and return to sport (RTS)-success in participants after an anterior cruciate ligament (ACL) reconstruction., Methods: Case-control study on 25 participants operated on with an arthroscopically assisted, anatomic ipsilateral quadriceps femoris tendon graft and two control groups of 25 participants each, operated on with a semitendinosus tendon or semitendinosus-gracilis (hamstring) tendon graft ACL reconstruction. Participants of the two control groups were propensity score matched to the case group based on sex, age, Tegner activity scale and either the total volume of rehabilitation since reconstruction (n = 25) or the time since reconstruction (n = 25). At the end of the rehabilitation (averagely 8 months post-reconstruction), self-reported knee function (KOOS sum scores), fear of loading the reconstructed knee during a sporting activity (RSI-ACL questionnaire), and fear of movement (Tampa scale of kinesiophobia) were followed by hop and jump tests. Front hops for distance (jumping distance as the outcome) were followed by Drop jumps (normalised knee joint separation distance), and concluded by qualitative ratings of the Balanced front and side hops. Between-group comparisons were undertaken using 95% confidence intervals comparisons, effect sizes were calculated., Results: The quadriceps case group (always compared with the rehabilitation-matched hamstring graft controls first and versus time-matched hamstring graft controls second) had non-significant and only marginal higher self-reported issues during sporting activities: Cohen's d = 0.42, d = 0.44, lower confidence for RTS (d = - 0.30, d = - 0.16), and less kinesiophobia (d =  - 0.25, d = 0.32). Small and once more non-significant effect sizes point towards lower values in the quadriceps graft groups in the Front hop for distance limb symmetry values in comparison to the two hamstring control groups (d =  - 0.24, d = - 0.35). The normalised knee joint separation distance were non-significantly and small effect sized higher in the quadriceps than in the hamstring groups (d = 0.31, d = 0.28)., Conclusion: Only non-significant and marginal between-graft differences in the functional outcomes at the end of the rehabilitation occurred. The selection of either a hamstring or a quadriceps graft type cannot be recommended based on the results. The decision must be undertaken individually., Level of Evidence: III., (© 2023. The Author(s).)

Purpose: The relationship between tibial bony and meniscus anatomy and knee kinematics during in vivo, high-impact activities remains unclear. This study aimed to determine if the posterior tibial slope (PTS) and meniscal slope (MS) are associated with in vivo anterior-posterior translation and internal tibia rotation during running and double-leg drop jumps in healthy knees., Methods: Nineteen collegiate athletes performed fast running at 5.0 m/s on an instrumented treadmill and double-leg drop jump from a 60 cm platform while biplane radiographs of the knee were acquired at 150 Hz. Tibiofemoral kinematics were determined using a validated model-based tracking process. Medial and lateral PTS and MS were measured using magnetic resonance imaging (MRI)., Results: In fast running, more internal tibia rotation was associated with greater PTS (ρ = 0.336, P = 0.039) and MS (ρ = 0.405, P = 0.012) in the medial knee compartment. In the double-leg drop jump, more internal tibia rotation was associated with greater PTS (ρ = 0.431, P = 0.007) and MS (ρ = 0.323, P = 0.005) in the medial knee compartment, as well as a greater PTS in the lateral knee compartment (ρ = 0.445, P = 0.005)., Conclusion: These findings suggest that the medial and lateral PTS and medial MS are associated with the amount of knee rotation during high-impact activities. These in vivo findings improve our understanding of ACL injury risk by linking bone and meniscus morphology to dynamic kinematics., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: The aim of this consensus project was to create a treatment algorithm for the management of the ACL-injured patient which can serve as an aid in a shared decision-making process., Methods: For this consensus process, a steering and a rating group were formed. In an initial face-to-face meeting, the steering group, together with the expert group, formed various key topic complexes for which various questions were formulated. For each key topic, a structured literature search was performed by the steering group. The results of the literature review were sent to the rating group with the option to give anonymous comments until a final consensus voting was performed. Sufficient consensus was defined as 80% agreement., Results: During this consensus process, 15 key questions were identified. The literature search for each key question resulted in 24 final statements. Of these 24 final statements, all achieved consensus., Conclusions: This consensus process has shown that ACL rupture is a complex injury, and the outcome depends to a large extent on the frequently concomitant injuries (meniscus and/or cartilage damage). These additional injuries as well as various patient-specific factors should play a role in the treatment decision. The present treatment algorithm represents a decision aid within the framework of a shared decision-making process for the ACL-injured patient., Level of Evidence: Level V., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: National registry data have established Knee injury and Osteoarthritis Outcome Score (KOOS) functional recovery target values for adults after anterior cruciate ligament (ACL) reconstruction. However, the specificity of these target values for young athletes after ACL reconstruction is unclear. The purpose of this analysis was to (1) derive age- and activity-relevant KOOS functional recovery target values from uninjured young athlete data and (2) determine clinical measures at the time of RTS clearance associated with meeting the newly-derived functional recovery target values in young athletes following ACLR., Methods: Two hundred and twenty-two young athletes (56 uninjured controls, 17.2 ± 2.4 years, 73% female; 166 after ACL reconstruction, 16.9 ± 2.2 years, 68% female) were included in this cross-sectional analysis from a larger cohort study. Uninjured control participants completed the KOOS, and functional recovery target values were defined as the lower bound of the 95% confidence interval for KOOS subscales. ACL reconstruction participants completed testing within 4 weeks of return-to-sport clearance, including the KOOS, single-leg hop tests, and isometric quadriceps strength. In ACL reconstruction participants, logistic regression was used to determine predictors of meeting all KOOS functional recovery target values (primary outcome) among demographic/injury, hop, and strength data (α ≤ 0.05)., Results: KOOS functional recovery target values for each subscale from uninjured athlete data were: Pain ≥ 94, Symptoms ≥ 92, Activities of Daily Living ≥ 97, Sport ≥ 92, and Quality-of-Life ≥ 92. At the time of return-to-sport clearance, ACL reconstruction participants met the KOOS functional recovery targets in the following proportions: Pain, 63%; Symptoms, 42%; Activities of Daily Living, 80%; Sport, 45%; Quality-of-Life, 24%; overall functional recovery (met all subscale targets), 17%. In ACL reconstruction participants, significant predictors of overall functional recovery (primary outcome) were: younger age, hamstring graft, pediatric ACL reconstruction, quadriceps strength limb-symmetry index > 90%, single-hop limb-symmetry index > 90%, and crossover-hop limb-symmetry index > 90%., Conclusions: KOOS functional recovery target values derived from uninjured young athletes were higher than those previously reported. Small proportions of young athletes following recent RTS clearance after ACLR met these newly-derived functional recovery target values, and factors associated with meeting functional recovery target values included younger age, hamstring autograft and pediatric ACLR, and having > 90% LSI for quadriceps strength and single-leg hop tests., Level of Evidence: I., (© 2021. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: The increasing incidence of knee injuries among children is well known by sports physicians. Papers dealing with this topic have often collected patient-reported outcomes measures (PROMs) in a retrospective manner; this limitation could lead to a misinterpretation of the results, because pediatric patients might not remember their preoperative conditions adequately. This study aims to evaluate the reliability and the reproducibility of the IKDC pediatric score when administered retrospectively at a 12-month follow-up., Methods: From September 2018 and June 2019, all patients aged 7-18 scheduled for surgery due to different knee pathologies in a single center were considered eligible. Parents were contacted by phone for consent. An open-source platform was implemented to collect the responses: two surveys were created (Q1, Q2). They included general information and the Pedi-IKDC score. Q1 was completed prospectively, while Q2 was completed 12 months after surgery. The two questionnaires were identical, and patients were carefully advised to complete Q2 recalling their health status before surgery. ICC and the concordance correlation coefficient (ρ c ) were used to assess the reproducibility between the prospective and recalled scores., Results: Sixty-six patients responded to Q1 and Q2, and the mean age was 12.9 ± 2.2 years at Q1 and 14.1 ± 2.2 years at Q2. The mean time between Q1 and Q2 was 14.1 ± 2.1 months. Between prospective-IKDC and recall-IKDC, the ICC coefficient was "poor" at 0.32 (CI 0.09 to 0.5) and the ρ c was "poor" at 0.4 (CI 0.29 to 0.51). Mean prospective-IKDC was 76.8 ± 23.52 mean recalled-IKDC was 60.4 ± 11.5 (P < 0.0001), while mean difference was -16.3 ± 2.09. Simple linear regression models showed that Δ-IKDC is independently associated with age at Q1 (R 2  = 0.2676; P0.0001)  and prospective-IKDC (R 2  = 0.653; P < 0.0001)., Conclusions: Retrospective collection of the Pedi-IKDC score is not reliable and has high recall bias. This should be avoided in children with knee conditions., Level of Evidence: III., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: To translate and culturally adapt the anterior cruciate ligament-return to sport after injury (ACL-RSI) scale into Italian (ACL-RSI(IT)) and examine and evaluate the psychometric properties of the Italian version in individuals who have undergone anterior cruciate ligament (ACL) reconstruction., Methods: The ACL-RSI was forward and back translated, culturally adapted and validated one hundred and twenty nine Italian individuals who had undergone ACL reconstruction (94 males, 35 females; age 28 ± 9 years). All patients completed the translated ACL-RSI, Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee subjective knee form (IKDC), Tampa Scale of Kinesiophobia (TSK) and the 12-item short form health survey (SF-12). We then analysed the internal consistency, reliability and validity of the newly formed ACLRSI (IT)., Results: The ACL- RSI(IT) showed excellent internal consistency (Cronbach's alpha 0.94) and was significantly correlated with the KOOS 'quality of life' (r = 0.61, p < 0.00001), 'symptoms' (r = 0.34, p < 0.00001), 'pain' (r = 0.44, p < 0.00001), and 'sports' (r = 0.40, p < 0.00001) subscales. The ACL-RSI(IT) also correlated significantly with the IKDC (r = 0.34, p < 0.001), TSK (r = - 0.48, p < 0.00001) and SF-12 (r = - 0.40, p < 0.0001) scores., Conclusion: The Italian version of the ACL-RSI scale was valid, discriminant, consistent and reliable in patients who had undergone ACL reconstruction. This score could be useful to evaluate the effect of psychological factors on return to sport following ACL surgery., Level of Evidence: II., (© 2020. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: The purpose of this study was to identify if the location of posterolateral corner (PLC) injury was predictive of clinical common peroneal nerve (CPN) palsy., Methods: A retrospective chart review was conducted of patients presenting to our institution with operative PLC injuries. Assessment of concomitant injuries and presence of neurologic injury was completed via chart review and magnetic resonance imaging (MRI) review. A fellowship-trained musculoskeletal radiologist reviewed the PLC injury and categorized it into distal, middle and proximal injuries with or without a biceps femoral avulsion. The CPN was evaluated for signs of displacement or neuritis., Results: Forty-seven operatively managed patients between 2014 and 2019 (mean age-at-injury 29.5 ± 10.7 years) were included in this study. Eleven (23.4%) total patients presented with a clinical CPN palsy. Distal PLC injuries were significantly associated with CPN palsy [9 (81.8%) patients, (P = 0.041)]. Nine of 11 (81.8%) patients with CPN palsy had biceps femoral avulsion (P = 0.041). Of the patients presenting with CPN palsy, only four (36.4%) patients experienced complete neurologic recovery. Three of 7 patients (43%) with an intact CPN had full resolution of their clinically complete CPN palsy at the time of follow-up (482 ± 357 days). All patients presenting with a CPN palsy also had a complete anterior cruciate ligament (ACL) rupture in addition to a PLC injury (P = 0.009), with or without a posterior cruciate ligament (PCL) injury. No patient presenting with an isolated pattern of PCL-PLC injury (those without ACL tears) had a clinical CPN palsy., Conclusion: Distal PLC injuries have a strong association with clinical CPN palsy, with suboptimal resolution in the initial post-operative period. Specifically, the presence of a biceps femoris avulsion injury was highly associated with a clinical CPN palsy. Additionally, CPN palsy in the context of PLC injury has a strong association with concomitant ACL injury. Furthermore, the relative rates of involvement of the ACL vs. PCL suggest that specific injury mechanism may have an important role in CPN palsy., Level of Evidence: IV., (© 2021. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: The purpose of this study was to systematically review case reports and case series about meniscal ossicle, to summarize existing evidence. Specifically, to identify the etiology, demographic characteristics, localization, clinical features, diagnostic procedures and treatment options of this rare entity. Although, case reports/ series are of low level of evidence, a systematic review of such studies can provide and help us to gain a better understanding and awareness of meniscal ossicle., Methods: Two authors searched three online databases (MEDLINE, SCOPUS and GOOGLE SCHOLAR) from inception until March 2020 for the literature on meniscal ossicle. Inclusion criteria included case series, case reports and case-based reviews, available in full-text version, in English and that concern humans. Reports published in languages other than English were excluded, as well as articles with no electronic full text availability. Case reports using the term "meniscal ossicle" to describe an acute avulsion fracture of the tibial root of the meniscus, were also excluded., Results: Of 453 initial studies, 38 studies satisfied inclusion criteria. In total 169 patients were included of whom 107 (63%) were males and 62 (37%) were females. Mean age was 44 years (range 12-87). According to Magnetic resonance imaging findings, in 144 knees (86%) the ossicle was localized at the posterior root or horn of the medial meniscus. 60% of the patients had a history of trauma. The predominant symptom in 87% of patients was knee pain. In all patients was detected an intra-articular density structure in computed radiography. 76% had associated meniscal tear, 61% had intraarticular cartilage loss, 34% meniscal extrusion and 28% anterior cruciate ligament injury. Treatment modalities included conservative regimen in 40 patients, while 59 patients underwent surgical excision., Conclusion: The most possible etiology of meniscal ossicle is posttraumatic heterotopic ossification and small occult bony avulsion fracture. It is commonly observed in individuals complaining about knee pain with history of antecedent trauma. The presence of a meniscal ossicle should alert the physician to the high likelihood of the patient having an associated meniscal tear, articular cartilage loss, ACL injury or meniscal extrusion. Along with the meniscal ossicle, the associated meniscal tear should be treated as well., (© 2020. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: To assess measurement equivalence, inter- and intra-rater reliability, standard error of measurements (SEM) and false positive measurements (FPM) of four different knee arthrometers (KLT,Karl Storz; KiRA, I + ; KT-1000 MEDmetric Corp; Rolimeter, Aircast) in healthy patients., Methods: Four different investigators (two advanced (AR) and two beginners (BR)) examined 12 participants with healthy knees at two time points with regards to anterior tibial translation (ATT) and side-to-side difference (SSD). Test equivalence was assessed using the TOST (two-one-sided t test) procedure with ± 1 mm equivalence boundaries. Intraclass correlation coefficients (ICCs) were calculated using two-way mixed effects models. Furthermore, false positive-(SSD > 3 mm) and SEMs were assessed., Results: A total of 2304 Lachman Tests were performed. Between-rater SSDs were equivalent between AR and BR raters for the Rolimeter only. Inter-rater ICC values (SSD, ATT) were graded as "poor" to "moderate" for all devices. Equivalent test-retest results were observed for all raters using the Rolimeter, KLT and KT-1000, whereas measurement consistency with KiRA was given in the advanced examiners group only. Intra-rater ICC values (Range: SSD, ATT) were graded as "poor" to "moderate" for SSD values and "moderate" to "good" for ATT. SEMs were lowest for the Rolimeter and highest for KiRA. FPM were never obtained with the Rolimeter (0%), twice (2.1%) with the KT-1000, three times (3.1%) with the KLT and 33 times (34.4%) using KiRA., Conclusion: There is acceptable intra-rater but poor inter-rater reliability with all tested arthrometers. Measures of knee laxity are comparable between Rolimeter, KLT and KT-1000 but higher for KiRA. Clinically, the present study shows that repeated arthrometry measurements should always be performed by the same investigators., (© 2021. The Author(s).)

Purpose: Medial collateral ligament (MCL) injury is very common and surgical repair is sometimes necessary. Especially in the setting of simultaneous anterior cruciate ligament reconstruction (ACLR) as the ACL is the secondary restraint against valgus stress. The goal of this study was to evaluate knee biomechanics after suture repair of the MCL augmented with suture tape, as compared to MCL repair alone, in the setting of concomitant ACL reconstruction (ACLR)., Methods: Fifteen fresh-frozen human cadaveric knees were tested using a six-degrees-of-freedom robotic system under four loadings: (a) an 89.0 N anterior tibial load, (b) a 5.0 Nm internal and external rotation torque, (c) a 10.0 Nm valgus load, (d) a 7.0 Nm valgus load combined with 5.0 Nm internal rotation torque as a static simulated pivot-shift. The tested conditions were ACLR with the following states: (1) MCL intact, (2) MCL deficient, (3) MCL Repair, and (4) MCL repair augmented with suture tape (MCL Repair + ST). Under the different knee loadings, the tibial displacement, and the force in either the intact MCL, suture repaired MCL or repaired MCL-suture tape complex was measured., Results: While neither the MCL Repair nor the MCL Repair + ST restored valgus rotation to the MCL intact state, displacement was significantly smaller after MCL Repair + ST (p < 0.05). The knee rotation under external rotation torque in MCL Repair + ST did not differ MCL intact (n.s.), while with MCL Repair the rotation was significantly greater (p < 0.05). MCL Repair + ST did not cause an over-constraint of the knee in any of the tested loading conditions., Conclusion: In a combined ACL-reconstruction-MCL-repair model, MCL Repair augmented with suture tape improved valgus and external rotation laxity when compared to MCL suture repair alone. Suture tape augmentation may provide this additional means of stabilization and can be added at the time of surgical repair of the MCL. Clinically this may result in lower failure rates and less residual laxity after MCL repair, as well as shorter immobilization times and faster return to play., (© 2021. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: The purpose of the present study was to determine how the medial structures and ACL contribute to restraining anteromedial instability of the knee., Methods: Twenty-eight paired, fresh-frozen human cadaveric knees were tested in a six-degree of freedom robotic setup. After sequentially cutting the dMCL, sMCL, POL and ACL in four different cutting orders, the following simulated clinical laxity tests were applied at 0°, 30°, 60° and 90° of knee flexion: 4 Nm external tibial rotation (ER), 4 Nm internal tibial rotation (IR), 8 Nm valgus rotation (VR) and anteromedial rotation (AMR)-combined 89 N anterior tibial translation and 4 Nm ER. Knee kinematics were recorded in the intact state and after each cut using an optical tracking system. Differences in medial compartment translation (AMT) and tibial rotation (AMR, ER, IR, VR) from the intact state were then analyzed., Results: The sMCL was the most important restraint to AMR, ER and VR at all flexion angles. Release of the proximal tibial attachment of the sMCL caused no significant increase in laxity if the distal sMCL attachment remained intact. The dMCL was a minor restraint to AMT and ER. The POL controlled IR and was a minor restraint to AMT and ER near extension. The ACL contributed with the sMCL in restraining AMT and was a secondary restraint to ER and VR in the MCL deficient knee., Conclusion: The sMCL appears to be the most important restraint to anteromedial instability; the dMCL and POL play more minor roles. Based on the present data a new classification of anteromedial instability is proposed, which may support clinical examination and treatment decision. In higher grades of anteromedial instability an injury to the sMCL should be suspected and addressed if treated surgically.

Purpose: The purpose of this study was to evaluate the role of surgeons' experience with meniscal repairs and meniscectomy decisions, and to determine the factors affecting the disagreement between meniscal repairs and meniscectomy decisions., Methods: In total, 223 patients with meniscal tears, 106 meniscal repairs, and 117 meniscectomies were included. Six orthopedic surgeons (3: > 5 years; 3: < 5 years' arthroscopy experience) were blinded, and they independently reviewed all preoperative MR images for over a month. Their reviews were compared with arthroscopic interventions performed by a surgeon with > 10 years' arthroscopy experience. Reparability-associated factors were also evaluated using multivariate logistic regression., Results: The first and second evaluation results did not differ significantly between groups (n.s.). There was good agreement between MRI predictions and arthroscopic interventions for both groups (< 5 years' experience: k = 0.248, agreement 62.3%; > 5 years' experience: k = 0.351, agreement 67.3%). Sex, side, and distance of tear from the meniscocapsular junction were not significantly different between agreements and disagreements. Disagreement regarding meniscectomy was significantly higher than those regarding meniscus repair (p = 0.002). Concomitant anterior cruciate ligament (ACL) injury, osteochondral lesions, and medial meniscal tear increased the likelihood of meniscal repair (p = 0.0063, p = 0.0010, and p = 0.0369, respectively). An increased risk of disagreement between MRI and surgical procedure was found in the presence of bucket-handle, horizontal or complex tear, chronic tear, high sports activity and expectation level., Conclusion: Surgeon's experience level may influence the prediction of meniscus reparability. Concomitant ACL injury, osteochondral lesions, and presence of medial meniscal tear increase the likelihood of meniscal repair. Tear type, tear chronicity, patient's activity and expectation level may influence the surgeon's operative decision in addition to MRI., Level of Evidence: III.

Purpose: The purpose of this study was to identify if abnormal tibial alignment was a risk factor for lateral meniscus posterior root tears (LMPRT) in patients with acute anterior cruciate ligament (ACL) ruptures., Methods: The medical charts of 200 patients treated for ACL ruptures between 2013 and 2016 were retrospectively reviewed and evaluated. MRI images and reports were assessed for concurrent meniscal tears. Radiographs were reviewed for tibia vara and tibial slope angles and MRI reports identifying lateral root tears were compared to intraoperative reports to determine accuracy. Multiple logistic regression models were constructed to identify potential risk factors for LMPRTs., Results: Of the 200 patients reviewed, a total of 97 individuals with concurrent meniscal injuries were identified. In patients sustaining a concurrent meniscal injury, there was a 4% incidence of medial meniscus posterior root tears and a 10.3% incidence of LMPRTs. Patients sustaining an ACL injury with an LMPRT were found to have greater tibia vara angles (4.2 ± 1.0 vs. 2.9 ± 1.7; p = 0.024), increased tibial slopes (12.6 ± 1.5 vs. 10.7 ± 2.9; p = 0.034), and higher BMIs (27.3 ± 2.9 vs. 25.3 ± 5.9; p = 0.034) when compared to patients without meniscus tears. There was low agreement between MRI and arthroscopic findings (kappa rate = 0.54). Multiple logistic regression analysis demonstrated that a tibia vara angle > 3 was associated with a 5.2-fold increase (95% CI 0.99-27.01; p = 0.050), and a tibial slope > 12 with a 5.4-fold increase (95% CI 1.03-28.19; p = 0.046) in LMPRTs., Conclusions: Patients with greater tibia varus angles, increased tibial slopes, and higher BMIs were found to have an increased risk of LMPRTs when sustaining an ACL rupture. There was a low rate of agreement between MRI and arthroscopy in identifying LMPRTs. In patients with ACL ruptures who have abnormal tibial alignment or increased BMI, physicians should be watchful for lateral meniscus posterior root tears., Level of Evidence: 3.

Purpose: Team handball is associated with a high risk of severe knee injury that needs to be reduced, particularly at the youth level. The purpose of this study was to show how an injury-prevention programme effectively reduces severe knee injury in adolescent team handball players., Methods: Of 23 adolescent handball teams of both sexes, 13 were randomly allocated into the intervention group (168 players) and 10 into the control group (111 players). Players of the intervention group regularly participated in an injury-prevention programme for one season. Handball exposure and sustained injuries were documented for both groups on a monthly basis. The primary outcome parameter of the injury-prevention programme was the incidence of severe knee injury., Results: Of the 279 included players, 68 (24%) sustained 82 injuries yielding an overall incidence of 1.85 injuries per 1000 h handball exposure (intervention group: 50 injuries/incidence: 1.90/1000 h; control group: 32 injuries/incidence: 1.78/1000 h). Knee injury was the second most frequent injury in adolescent team handball. The primary outcome parameter, severe knee injury occurred significantly more often in the control group [mean age (SD) 15.1 (1.0), injury incidence 0.33/1000 h] than in the intervention group [mean age (SD) 14.9 (0.9), injury incidence 0.04/1000 h]. The odds ratio was 0.11 (95% CI 0.01-0.90), p = 0.019. Other injuries to the lower extremities showed no significant difference between the two groups., Conclusions: Frequent neuromuscular exercises prevent severe knee injury in adolescent team handball players and should thus be included in the practical routine as well as in the education of team coaches.

Purpose: Ramp lesions are common in ACL deficient knees. Their diagnosis is difficult and, therefore, they may be underestimated. So far, no study analyzed their prevalence in a pediatric population. The diagnosis of these Ramp lesions is of major clinical relevance because of a frequent misestimating and technic difficulties. Ramp lesions might be associated with residual knee pain and instability after ACL reconstruction. The aim of this study was to evaluate the prevalence of ramp lesions explored through a systematic intercondylar and posteromedial arthroscopic approach during an ACL reconstruction in a pediatric and adolescent population., Methods: Children and adolescents who underwent an ACL reconstruction were screened prospectively between October 2014 and 2016. The presence or absence of a ramp lesion was evaluated after each of three arthroscopic steps: (1) an anterior approach, (2) an intercondylar inspection, and (3) a posteromedial approach. Ramp lesions were screened at each step and their prevalence was evaluated. Furthermore, their presence was correlated to age, weight, size, sex, and state of the physis (open or closed). Finally, the meniscal status on MRI and arthroscopic findings were compared., Results: Fifty-six patients were analyzed. The median age was 14.0 ± 1.3 years (12-17). The median interval between injury and surgery was 11.5 months (1-108). During step 1 (anterior approach), only 1 ramp lesion (2%) was diagnosed. 13 (23%) ramp lesions were found after inspection through the intercondylar notch. No additional lesions were found with a direct view through the posteromedial approach. No correlation between ramp lesions and side, sex, weight, size, or state of physis was found. 10 ramp lesions out of 13 could not be diagnosed on MRI., Conclusions: The prevalence of ACL-associated ramp lesions in children and adolescents is similar to adult populations. A systematic inspection through the intercondylar notch is recommended during ACL reconstruction to make a precise diagnosis. The posteromedial approach is essentially useful for meniscal repair LEVEL OF EVIDENCE: Testing, previously developed diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level I.

Purpose: The purpose of this study is to assess the results of revision anterior cruciate ligament (ACL) reconstruction after the failure of primary ACL double bundle reconstruction (ACL-DBR)., Methods: Twenty-two knees in 22 patients (group R) that underwent ACL revision surgery using bone-patellar tendon-bone (BTB) autograft after the failure of primary ACL-DBR were included in this study. Intraoperative findings and postoperative knee laxity and clinical outcomes in group R were assessed. Forty-four knees in 44 patients that were age- and gender- matched with group R and underwent primary ACL reconstruction using BTB autograft were used as a control group (group P)., Results: The incidence of medial meniscus and cartilage injury in group R was significantly higher than those in group P (p < 0.05). At final follow-up, median Lysholm score was 90.5 (64-100) in group R and 94 (59-100) in group P, respectively. Fourteen patients (63.6%) in group R and 31 patients (70.5%) in group P were able to return to previously-played sports, respectively. There were no significant differences in KT-1000 outcomes (2.0 mm in group R and 1.4 mm in group P) or pivot shift test between the two groups. The rate of subsequent ACL injury was similar in both groups., Conclusions: Revision ACL reconstruction using BTB autograft after failed primary ACL-DBR provided almost compatible postoperative clinical outcomes and knee stability with primary ACL reconstruction using BTB autograft, while the incidence of medial meniscus and cartilage injury at revision surgery was higher., Level of Evidence: Retrospective comparative study, Level III.

Purpose: The purpose of this study was to evaluate whether the ACL tibial footprint size can be predicted by anthropometric variables including height, weight, leg length, femur length, tibia length, and anteroposterior and mediolateral diameters of proximal tibia., Methods: This study included 209 out of the 378 eligible patients. The inclusion criterion was ACL with normal gross appearance. Patients with conditions that could have affected the measurement were excluded: torn ACL, osteophyte formation around the ACL tibial attachment, presence of inflammatory arthritis, or history of knee joint infection. According to the above criteria, 169 patients were excluded from this study; 138 had torn ACL, 24 had osteophyte around the ACL footprint, 5 had history of rheumatoid arthritis, and 2 had history of previous knee joint infection. The ACL tibial footprint was carefully dissected and measured during total knee arthroplasty. Anthropometric variables regarding bone lengths were measured on radiography. The association of the ACL tibial footprint size (length and width) with anthropometric variables was analysed using simple and multiple linear regression analyses., Results: The height, weight, leg length, femur length, tibia length, and the size of proximal tibia were associated with the ACL tibial footprint length and width. The ACL tibial footprint length could be predicted by the equation using tibia length: ACL tibial footprint length = -9.361 + 0.759 * (tibia length in cm) (R 2  = 0.44, P < 0.001) and width by the equation using weight and tibia length: ACL tibial footprint width = -0.5615 + 0.279 * (tibia length in cm) + 0.0333 * (weight in kgs) (R 2  = 0.17, P < 0.001). The concordance correlation coefficient for the measured and predicted values of ACL tibial footprint length and width showed moderate and low agreement, respectively (0.61, 95 % CI 0.53-0.68; 0.30, 95 % CI 0.21-0.38)., Conclusion: The ACL tibial footprint length and width are associated with anthropometric variables, especially with tibial length. The predictive equation developed from this study can serve as supplementary guides to determine the surgical techniques and graft options in preoperative planning of an individual ACL reconstruction., Level of Evidence: IV.

This article reviews the evidence for the roles of the anterolateral soft-tissue structures in rotatory stability of the knee, including their structural properties, isometry, and contributions to resisting tibial internal rotation. These data then lead to a biomechanical demonstration that the ilio-tibial band is the most important structure for the restraint of anterolateral rotatory instability. Level of evidence V.

Purpose: The function of the anterior cruciate ligament (ACL) patients' non-injured leg is relevant in light of the high incidence of secondary ACL injuries on the contralateral side. However, the non-injured leg's function has only been examined for a selected number of neuromuscular outcomes and often without appropriate control groups. We measured a broad array of neuromuscular functions between legs of ACL patients and compared outcomes to age, sex, and physical activity matched controls., Methods: Thirty-two ACL-deficient patients (208 ± 145 days post-injury) and active and less-active controls (N = 20 each) participated in the study. We measured single- and multi-joint neuromuscular function in both legs in each group and expressed the overall neuromuscular function in each leg by calculating a mean z-score across all neuromuscular measures. A group by leg MANOVA and ANOVA were performed to examine group and leg differences for the selected outcomes., Results: After an ACL injury, duration (-4.3 h/week) and level (Tegner activity score of -3.9) of sports activity decreased and was comparable to less-active controls. ACL patients showed bilateral impairments in the star excursion balance test compared to both control groups (P ≤ 0.004) and for central activation ratio compared to active controls (P ≤ 0.002). There were between-leg differences within each group for maximal quadriceps and hamstring strength, voluntary quadriceps activation, star excursion balance test performance, and single-leg hop distance (all P < 0.05), but there were no significant differences in quadriceps force accuracy and variability, knee joint proprioception, and static balance. Overall neuromuscular function (mean z-score) did not differ between groups, but ACL patients' non-injured leg displayed better neuromuscular function than the injured leg (P < 0.05)., Conclusions: Except for poorer dynamic balance and reduced quadriceps activation, ACL patients had no bilateral neuromuscular deficits despite reductions in physical activity after injury. Therapists can use the non-injured leg as a reference to assess the injured leg's function for tasks measured in the present study, excluding dynamic balance and quadriceps activation. Rehabilitation after an ACL injury should be mainly focused on the injured leg., Level of Evidence: III.

Purpose: To compare the range of motion (ROM) and radiography of the hip joints in male patients with contact anterior cruciate ligament (ACL) injury and non-contact ACL injury., Methods: ROM of the ipsilateral hip was evaluated in 35 male patients with contact ACL injury (contact group) and compared to that of 45 male patients with a non-contact ACL injury (non-contact group). Radiographic evaluation of hip joints was also performed to assess the presence of cam and pincer-type deformity ., Results: ROM of the hip joint was statistically higher in patients with contact ACL injury. The average sum of hip rotation in the non-contact group was 66.1 ± 8.4° compared to 79.4 ± 10.6° for the contact group (p < 0.001). Seventy-seven per cent of patients in the non-contact group had a sum of hip rotation <70° and 93 % had <80°, compared to17.1 and 42.9 % in the contact group (p < 0.001). Prevalence of cam or pincer deformity was similar in the groups. Cam or pincer deformity was not more frequent in patients with limited ROM of the hip., Conclusion: Individuals with contact ACL injury had greater ROM of the hip joints than those with non-contact ACL injury. The presence of cam or pincer deformity was similar in both groups and was not related to decreased ROM of the hip joints. These findings may assist the surgeons to identify new risk factors for non-contact ACL injury and, additionally, develop prevention program of injury., Level of Evidence: III.

Purpose: To determine whether the bathing of an anterior cruciate ligament (ACL) autograft in vancomycin reduces the rate of infection following an ACL reconstruction., Methods: Retrospective analysis of all ACL reconstructions over an 8-year period in two University Hospitals. In the initial 4-year period, all patients were operated on under classical antibiotic intravenous prophylaxis (group 1). Over the last 4-year period, this prophylaxis was supplemented with presoaking of the autograft (group 2). Presoaking was performed with sterile gauze previously saturated with a vancomycin solution (5 mg/ml)., Results: There were 810 and 734 patients in group 1 and 2, respectively. Fifteen cases of knee joint infections were identified in the series (0.97 %). All of these infections occurred in group 1, representing a rate of infection of 1.85 % in comparison with 0 % in group 2 (p < 0.001)., Conclusions: Autograft presoaking with vancomycin in combination with classical intravenous antibiotic prophylaxis reduced the rate of knee joint infection following an ACLR in comparison with antibiotic prophylaxis alone. This technique could be of relevance in daily clinical practice to prevent infection after ACLR., Level of Evidence: Case control study, retrospective comparative study, Level III.

Purpose: Pretensioning and preconditioning of soft tissue grafts are often performed to obviate graft stress relaxation and elongation due to viscoelastic graft properties following anterior cruciate ligament (ACL) reconstruction. It was hypothesized that a consensus could be identified in the current literature regarding the biomechanical effects and clinical benefits of an optimal protocol., Methods: A systematic electronic literature search was performed by two independent reviewers to identify relevant publications. Only studies describing and/or comparing pretensioning or preconditioning protocols of soft tissue grafts or equivalent animal research models were eligible for inclusion. Study design, graft type, and protocol, including method, magnitude, mode (cyclic and/or static loading), and duration of load application, were compared. Research results and clinical conclusions were also evaluated for each study., Results: Five studies, including four in vitro biomechanical investigations and one histological analysis of patient tissue, met the predefined criteria for inclusion. Studies described numerous pretensioning and/or preconditioning protocols with varying force, time, and application modalities for multiple soft tissue graft types and animal models. The majority of studies (80 %) utilized at least one pretensioning or preconditioning protocol between 80 and 89 N, while only one study investigated substantially higher loads (500 N)., Conclusions: Despite common trends demonstrating the effects of pretensioning and preconditioning, no clear consensus regarding an optimal protocol, magnitude, or modality could be identified within the currently available relevant literature. Further multidisciplinary research is required before an optimal or consensus protocol can be established for soft tissue ACL reconstruction. Regardless, the current biomechanical literature demonstrates the potential clinically beneficial effects of pretensioning and preconditioning, including reduced graft elongation and greater preservation of graft tension and stiffness following fixation., Level of Evidence: Systematic review, Level II.

Purpose: Management of anterior cruciate ligament injuries in skeletally immature patients (in Tanner stages 2 and 3) is controversial. Conventional reconstruction used in adults can cause iatrogenic growth disturbance due to physeal damage, and studies that report long-term results using a specific technique are scarce. The aim of this study is to evaluate in a large series the mid- and long-term results of a partial transphyseal technique and define the safe percentage of lesions of the femoral growth plate., Methods: Between 1989 and 2012, 42 adolescents at risk of growth disturbances (growth prediction of lower limbs >5 cm-Tanner 2, 3) underwent reconstruction of the anterior cruciate ligament using the semitendinosus and gracilis tendons. Growth characteristics of all the patients were assessed preoperatively, and the percentage of damage that would be produced in the femoral physis by the drilling of a 6-mm-diameter tunnel was determined. The technique used achieved graft fixation at both insertion sites, drilling the femoral physis and avoiding the tibial physis. We distinguished two groups: (a) long-term follow-up (mean 13 years 7 months, min 10.9, max 16.2) and (b) medium follow-up (mean 6 years 3 months, min 3.7, max 9.9). All knees were evaluated subjectively by history and objectively by KT2000 testing, and X-rays of both knees were compared for osteoarthritis using the Kellgren-Lawrence classification., Results: In group A (12 patients) one osteoarthritis grade 2, one instability, and ten good stability and function were observed. The mean KT2000 arthrometer values at 30 lb showed a difference of +2.4 mm (range 1-4 mm) between the operated and non-operated sides (p < 0.05). In group B (21 patients) no growth disturbance of the lower limbs, two failures (reinjury while participating in pivoting sports), and 19 good stability and function were observed. The mean KT2000 arthrometer values at 30 lb showed a difference of +1.9 mm (range 1-5 mm) between the operated and non-operated sides (p < 0.05). The average IKDC score of all the patients was 90 (min: 68, max: 97). None of the adolescents had consequences on growth after an eccentric damage passing tendons less than 7% on the frontal plane and of 1% on cross-sectional area of the femoral physis, and after an oblique tunnel passing 6-mm-diameter tendons of the tibial epiphyseal nucleus., Conclusions: This study defines the possibility to perform a partial transphyseal intra-articular ACL reconstruction in patients in Tanner stages 2 and 3 that avoids tibial physis, involves the distal femoral physis, and produces good results at mid- and long-term follow-up without causing growth disturbances., Level of Evidence: IV.

Purpose: Cartilaginous tibial eminence fracture (CTEF) is a new pattern of ACL rupture in children under the age of nine. MRI signs have been recently reported, but no series gave information about outcomes. It was hypothesized that primary treatment gave better results than delayed management due to frequent misdiagnosis., Method: This retrospective study focused on 15 patients, managed acutely (n = 7) or delayed (n = 8). The patients' median age at the time of initial injury was 6.5 years (range 5-9). Lysholm, IKDC 2000 subjective scores, and the measurement of the residual laxity by a side-to-side difference with a KT-1000 junior arthrometer were used at the time of revision., Results: After a mean follow-up of 9.8 years (range 1-18.5), the mean Lysholm and IKDC subjective scores were, respectively, 97.7 ± 2.6 and 97 ± 3.4. The median residual laxity was 2 mm (range 0-4). Non-operative treatment lead to 2 failures: intermeniscal ligament entrapment and combined avulsion fracture at the femoral site. Suture fixation of the avulsed fragment allows regularly good results when performed acutely or even 4 years after the injury. The hypothesis that primary treatment gives better result than delayed treatment tends to be wrong as 2 failures were reported in each group. An ACL reconstruction was performed in 3 out of the 4 treatment failures. Progressive resorption of the avulsed fragment was noticed in 3 of the 4 failures suggesting an associated ACL resorption., Conclusion: CTEF has a good prognosis even after misdiagnosis and treatment at the time of non-union; this could be due to low-energy mechanism of injury and low rate of associated lesion. Orthopaedic treatment for acute minimally displaced fractures is only indicated under strict MRI control, and suture fixation is the recommended strategy in other situations. Conservative management of non-union could expose to ACL involution and cannot be recommended., Level of Evidence: Retrospective case series, Level IV.

Purpose: To review the current knowledge on anterior cruciate ligament (ACL) injury prevention and ACL rehabilitation in individuals who have not yet reached musculoskeletal maturity., Methods: This is a narrative review based on a targeted and systematic literature search for paediatric ACL injury risk factors, injury prevention and rehabilitation., Results: The search strategies resulted in 119 hits on risk factor studies, 57 hits on prevention and 37 hits on rehabilitation. Modifiable risk factors for ACL injury are largely unknown in the paediatric population. ACL injury prevention using neuromuscular training is highly successful in the adolescent population, and existing injury prevention programmes are cost-effective. The efficacy of ACL injury prevention programmes in children is, however, investigated to a markedly lesser degree. Paediatric ACL injury rehabilitation is poorly described, although supervised active rehabilitation progressed through phases with functional milestones is generally encouraged., Conclusion: Although limited, current evidence supports implementation of injury prevention programmes in female football players from the age of 12. Supervised active rehabilitation where progression is guided by functional milestones is also advocated. Future identification of modifiable risk factors is needed to design prevention programmes for younger children. There is a need for international multicentre studies on treatment algorithms and rehabilitation to increase knowledge on the short- and long-term outcomes following existing algorithms., Study Design: Narrative review, level III.

Purpose: To identify predictors for additional anterior cruciate ligament (ACL) reconstruction., Methods: Patients from the Swedish national ACL register who underwent ACL reconstruction between January 2005 and February 2013 (follow-up duration 6-104 months) were included. Cox regression analyses included the following independent variables regarding primary injury: age, sex, time between injury and primary ACL reconstruction, activity at primary injury, concomitant injuries, injury side, graft type, and pre-surgery KOOS and EQ-5D scores., Results: Among ACL reconstruction procedures, 93% involved hamstring tendon (HT) autografts. Graft type did not predict additional ACL reconstruction. Final regression models only included patients with HT autograft (n = 20,824). Of these, 702 had revision and 591 contralateral ACL reconstructions. The 5-year post-operative rates of revision and contralateral ACL reconstruction were 4.3 and 3.8%, respectively. Significant predictors for additional ACL reconstruction were age (fourfold increased rate for <16-year-old patients vs. >35-year-old patients), time between injury and primary surgery (two to threefold increased rate for ACL reconstruction within 0-90 days vs. >365 days), and playing football at primary injury., Conclusion: This study identified younger age, having ACL reconstruction early after the primary injury, and incurring the primary injury while playing football as the main predictors for revision and contralateral ACL reconstruction. This suggests that the rate of additional ACL reconstruction is increased in a selected group of young patients aiming to return to strenuous sports after primary surgery and should be taken into consideration when discussing primary ACL reconstruction, return to sports, and during post-surgery rehabilitation., Level of Evidence: II.

Purpose: The aim of this systematic review was to apply the anatomic ACL reconstruction scoring checklist (AARSC) and to evaluate the degree to which clinical studies comparing single-bundle (SB) and double-bundle (DB) ACL reconstructions are anatomic., Methods: A systematic electronic search was performed using the databases PubMed (MEDLINE), EMBASE and Cochrane Library. Studies published from January 1995 to January 2014 comparing SB and DB ACL reconstructions with clinical outcome measurements were included. The items from the AARSC were recorded for both the SB and DB groups in each study., Results: Eight-thousand nine-hundred and ninety-four studies were analysed, 77 were included. Randomized clinical trials (29; 38%) and prospective comparative studies (29; 38%) were the most frequent study type. Most studies were published in 2011 (19; 25%). The most commonly reported items for both SB and DB groups were as follows: graft type (152; 99%), femoral and tibial fixation method (149; 97% respectively), knee flexion angle during graft tensioning (124; 8%) and placement of the tibial tunnel at the ACL insertion site (101; 66%). The highest level of documentation used for ACL tunnel position for both groups was often one dimensional, e.g. drawing, operative notes or o'clock reference. The DB reconstruction was in general more thoroughly reported. The means for the AARSC were 6.9 ± 2.8 for the SB group and 8.3 ± 2.8 for the DB group. Both means were below a proposed required minimum score of 10 for anatomic ACL reconstruction., Conclusions: There was substantial underreporting of surgical data for both the SB and DB groups in clinical studies. This underreporting creates difficulties when analysing, comparing and pooling results of scientific studies on this subject.

Purpose: This study aimed to: (1) examine whether the association between posterior tibial slope and noncontact ACL injury exists in Chinese population; (2) compare the reliability and consistency of the three methods (longitudinal axis, posterior and anterior tibial cortex axis) in lateral radiograph., Methods: Case-control study contained 146 patients in total (73 noncontact ACL injuries and 73 meniscus injuries, matched for age and gender), which were verified by arthroscopy, MRI and physical examination., Results: For the total population and the male subgroup, the mean posterior tibial slope of the ACL-injured group was significantly higher than that of the control group (P < 0.001). In addition, the longitudinal axis method exhibited the highest inter-rater (0.898) and intrarater reliability (0.928), whereas the anterior tibial cortex was the most variable (inter-rater reliability, 0.805; intrarater reliability, 0.824). The anterior tibial cortex method produced largest posterior tibial slope measurements (13.8 ± 3.3 for injury group; 11.6 ± 2.7 for control group), while the posterior tibial cortex method was the smallest (9.1 ± 3.1 for injury group; 7.2 ± 2.6 for control group). All three methods were not affected by age, sex, height, weight and BMI (n.s.)., Conclusions: The results of this study suggested that an increased posterior tibial slope was associated with the risk of noncontact ACL injury in Chinese population. Meanwhile, the longitudinal axis method is recommended for measuring posterior tibial slope in lateral radiograph in future studies. Posterior tibial slope measured by longitudinal axis method may be used as predictor of ACL injury., Level of Evidence: Case-control study, Level III.

Purpose: Anterior cruciate ligament reconstructions (ACLRs) in skeletally immature patients are increasing. The purpose of this study is to describe the demographics, graft usage, revision, and re-operation rates in skeletally immature ACLRs in the Kaiser Permanente healthcare system., Methods: Skeletally immature patients (<17.0 years old with open physes) were identified using the Kaiser Permanente ACLR registry. Multi-ligament reconstructions and physeal-sparing ACLRs were excluded. Aseptic revision and same-knee re-operation were the outcomes of interest. Exposure of interest was graft type; bone-patellar-tendon-bone (BPTB) autograft, hamstring autograft, and any type of allograft. Age, gender, body mass index (BMI), and race were evaluated as confounders. Cox proportional hazard models stratified by surgeon were used to analyse the risk of revision and re-operation., Results: A total of 534 primary ACLR cases were evaluated with a mean follow-up of 2.9 years. The majority were hamstring autografts (n = 388, 72.7%), male (n = 339, 63.9%), and White (n = 232, 43.4%). Median age was 14.9 years, and median BMI was 21.9 kg/m(2). There were 44 (8.2%) aseptic revisions and 48 (9.0%) same-knee re-operations. The incidence rate for revision was BPTB autograft 5.5%, hamstring autograft 7.5%, and allograft 13.2%. After adjusting for confounders and surgeon clustering effect, the risk of aseptic revision and revision between allograft and hamstring autograft did not reach statistical significance., Conclusion: Graft selection differs in skeletally immature patients with a preponderance of surgeries being performed with hamstring tendon autografts. High revision rates were identified for all graft types used, though differences in revision rates across different graft types did not reach statistical significance. Surgeons should be aware of high rates of revision in this skeletally immature young population, although type of graft used did not appear to make a difference., Level of Evidence: III.

Purpose: The aim of the study was to evaluate, in a group of adolescents, the onset of varus-valgus deviations in the sagittal plane after performing a trans-tibial trans-epiphyseal technique of ACL reconstruction with a follow-up of at least 2 years., Methods: Seventy-one patients aged 12-15 years old (Tanner scale 3 and 4) have undergone ACL reconstruction with STG using arthroscopy. All patients were evaluated clinically using the visual analogue scale (VAS), the Lysholm score and the Tegner activity score at the time of surgery. All patients were reevaluated after a follow-up period of at least 2 years (T1) using the VAS, the Lysholm score, the Tegner activity score and radiographic studies in order to compare the operated limb with the healthy control limb., Results: Valgus difference exceeding 2° in the knee axis between the operated limb and the healthy control limb was observed only in three patients (4.2%: 95% CI 0.88-11.86%). The average difference was <1° (0.3°, 95% CI 0.0-0.55)., Conclusion: The trans-tibial trans-epiphyseal technique of ACL reconstruction, according to the results obtained, seems to be a valid alternative procedure, when performed by a skilled orthopaedic surgeon, offering an excellent safety profile and at the same time very good clinical results., Level of Evidence: IV.

Purpose: To analyse the clinical, rotational and radiological (MRI) results of paediatric anatomical "C-shaped" double-bundle (DB) anterior cruciate ligament (ACL) reconstruction with anteromedial and posteromedial bundle compared to single-bundle (SB) ACL reconstruction., Methods: Between 2008 and 2014, 57 consecutive patients received a paediatric ACL reconstruction with open physis and were allocated into two groups, according to the surgical procedure. Transepiphyseal SB technique was used until 2012 and DB consecutively thereafter. Follow-up consisted of a clinical evaluation with assessment of the International Knee Documentation Committee (IKDC) form, the Lysholm knee score, Tegner activity score, KT-1000 arthrometer evaluation, VAS Scores for satisfaction, MRI and testing of rotational stability using a robotic system., Results: The mean time from ACL reconstruction to follow-up was 48.1 ± 15.8 in the SB group (n = 17) and 23.1 ± 13.2 in the DB group (n = 16; p < 0.001). No differences were found in the subjective scores. Biomechanically, there were significant differences identified in the KT-1000 (p < 0.03) and total tibial axial rotation (p < 0.04) when evaluating the reconstructed knee only. Ten of 17 (59%) of the SB patients had a Joint Play Area within the acceptable range of the median healthy knee value compared to 100 % in the DB group. Decreased patient satisfaction was associated with increased total tibial axial rotation. No growth disturbance was observed. Overall, 98% of patients were reached and either examined or interviewed. Re-rupture rate was 3 of 21 (14.3%) for DB and 9 of 35 (25.7%) for SB. All but one re-ruptures (92%) happened in the first 16 postoperative months independent of technique., Conclusions: The re-rupture rate after pre-adolescent ACL reconstruction is too high both historically and in this mixed cohort. Anatomical transepiphyseal DB ACL reconstruction with open physis may result in a reduction in this re-rupture rate, which may be related to a tighter control of the Joint Play Area. While subjective clinical results were similar between SB and DB, decreased patient satisfaction was associated with increased total tibial axial rotation in the entire cohort. Despite the need for two transepiphyseal tunnels in the DB technique, there did not appear to be an increased risk in growth plate disturbance. Transepiphyseal DB ACL reconstruction appears to be a reasonable alternative to current techniques in pre-adolescent children with an ACL rupture., Level of Evidence: IV.

Purpose: The aim of this study was to investigate whether a familiar correlation with anterior cruciate ligament (ACL) injury exists between competitive alpine skiers and their parents., Methods: All 593 (293 males, 300 females) elite alpine skiers who have studied at a Swedish alpine Ski High School during 2006 and 2012 answered a questionnaire whether they or their parents had suffered an ACL injury. A total of 418 skiers (70%) answered the questionnaire., Results: Twenty-nine per cent (n = 19) out of the 65 ACL-injured skiers reported that they had a parent (mother or father) who have had an ACL injury. In skiers without an ACL injury (n = 353), the result was 18% (n = 64). An odds ratio of 1.95 (95% confidence interval 1.04-3.65) was found to suffer an ACL injury if you have a parent who has had an ACL injury compared with if you have a parent without any ACL injury., Conclusion: The findings of the current study demonstrated a family history to tear the ACL between alpine skiers who had studied at a Swedish Ski High School and ACL injuries of their parents., Level of Evidence: III.

Purpose: The aim of this study was to evaluate whether the anthropometric and demographic measures of patients under 18 years can be used to predict the diameter of STG autograft in ACL reconstruction surgery., Methods: Retrospective series of 169 patients under 18 years (112 men, 57 women, average age 15.8 years) underwent ACL reconstruction surgery with STG autograft. We recorded anthropometric measures (weight, height and BMI), demographics (age and gender) and autograft diameter used. Correlation coefficients, linear regression and unpaired t test were used to determine the relationship between anthropometric/demographic variables and the diameter of the graft. p values <0.05 were considered statistically significant., Results: Correlation analysis showed a significant positive relation between height and graft diameter (r = 0.483, p < 0.0001) as well as between weight and graft diameter (r = 0.248, p = 0.001). However, age and BMI did not correlate with graft thickness (r = 0.098 and p = 0.203, r = 0.009 and p = 0.905, respectively). The mean graft diameter in men was 8.2 (range 6-10) and 7.5 in women (range 6-9), a difference that was statistically significant (p < 0.001)., Conclusions: Prediction of the STG graft diameter according to the height of the patient is an easy and reliable method in children and adolescents. These data may provide relevant preoperative information about the need of an alternative graft source and can be useful when counselling patients., Level of Evidence: IV.

Purpose: To survey and describe the treatment of paediatric anterior cruciate ligament (ACL) injuries performed by orthopaedic surgeons affiliated with the European Society for Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA)., Methods: A closed e-survey was submitted to all registered members and affiliates of ESSKA in July 2013. All recipients were invited to participate in the survey by answering 34 questions online. The list of potential respondents was extracted from the ESSKA office database., Results: Invitation was sent to 2236 ESSKA members and affiliates, and received 491 (22%) unique responses. Among the respondents, 445 (91%) were orthopaedic surgeons, with 354 (72%) stating that they were involved in treatment of paediatric ACL injuries. The main findings were that there are substantial differences with regard to preferred treatment algorithms, surgical techniques and long-term follow-up procedures. The summed estimate of skeletally immature children with ACL injury seen by the responders in 2012 was minimum 1923 individuals, and a minimum of 102 clinically relevant post-operative growth disturbances were registered., Conclusion: The present survey documents that the incidences of paediatric ACL injuries and idiopathic growth disturbances may be higher than previously estimated. Treatment algorithms and surgical techniques are highly diverse, and consensus could not be identified. It is worrying that only half the surgeons reported to follow-up children until skeletal maturity after surgical treatment. The results of this survey highlight the importance of international multicentre studies on paediatric ACL treatment and the development of an outcome registry to enable prospective data collections., Level of Evidence: IV.

Purpose: Anterior cruciate ligament (ACL) injuries in siblings are commonly observed in the clinic. One, possibly genetic, factor contributing to the pathogenesis of sibling injuries may be narrow intercondylar notches, which are well recognized as predisposing to ACL injury. This study aimed primarily to: (1) assess the incidence of ACL injuries in siblings within an existing study cohort, (2) compare intercondylar notch width size in injured compared to matched uninjured control siblings and (3) compare the number of injured versus control sibling pairs sharing a narrow notch., Methods: Twenty-four ACL-injured siblings from 10 families were matched for age, gender, family composition and sports activity, with 24 uninjured siblings from another 10 families. Intercondylar radiographs were taken to calculate anterior and posterior notch width indices (NWI). Notch size and the number of narrow notches in sibling pairs were compared between groups., Results: Thirteen of 72 ACL-study participants had siblings with torn ACLs. Mean anterior NWI was 0.18 and 0.24 (p < 0.001), and mean posterior NWI was 0.26 and 0.3 (p = 0.006) for injured and uninjured siblings, respectively. Sixty percent of injured sibling pairs shared a narrow notch, while no uninjured sibling pairs did so (p = 0.003)., Conclusion: This study showed that siblings (and often sibling pairs) with injuries do have significantly narrower notches than those without. This could partly explain the prevalence of ACL injuries in siblings. To reduce ACL-injury rates, we advise that siblings of ACL-injured athletes with narrow notches, be radiologically screened, and if necessary, cautioned and counselled regarding preventative training., Level of Evidence: Case-control study, Level III.

The purpose of this report was to describe the surgical technique for and outcomes after a modified physeal-sparing posterolateral corner reconstruction in a 12-year-old skeletally immature male with a mid-substance fibular collateral ligament tear, a proximal posterior tibiofibular ligament tear, and an anterior cruciate ligament avulsion fracture of the medial tibial eminence. A modified physeal-sparing posterolateral corner reconstruction was used to provide a near-anatomic reconstruction of the fibular collateral ligament and proximal posterior tibiofibular ligament. An anterior cruciate ligament repair was also performed. Varus stress radiographs obtained at 6 months postoperatively demonstrated resolution of lateral knee stability. Physical examination results demonstrated stability to anterior tibial translation and a stable proximal tibiofibular joint. Computed tomography showed that the surgical technique successfully avoided breeching the patient's physes.

Purpose: Quadriceps activation failure is considered to contribute to the weakness that lingers following anterior cruciate ligament (ACL) reconstruction. Importantly, the impact of pre-operative quadriceps activation on post-operative quadriceps function is unknown. Understanding this relationship is clinically important; as the counteractive approach clinicians should employ pre-operatively to mitigate post-operative quadriceps weakness is unclear. Accordingly, the primary purpose of this study was to investigate the relationship between pre-operative quadriceps activation and post-operative quadriceps strength and activation., Methods: Fifty-four individuals post-ACL injury reported for testing on two occasions: prior to surgery and post-surgery once they returned to activity. Quadriceps activation was assessed using the burst superimposition technique and quantified using the central activation ratio. Quadriceps strength was assessed using isometric contractions that were performed at 90° of knee flexion. Multiple linear regressions were utilized to detect the relationships between pre-operative activation and strength and post-operative activation and strength., Results: Pre-operative activation was not associated with post-operative strength (R(2) = 0.064, P = 0.186). Pre-operative quadriceps activation and strength were associated with post-operative activation (R(2) = 0.383, P ≤ 0.001) and strength (R(2) = 0.465, P ≤ 0.001), respectively., Conclusions: Individuals with better pre-operative quadriceps activation demonstrated greater post-operative activation. Similarly, individuals with better pre-operative strength demonstrated better post-operative strength. Pre-operative quadriceps activation was not a predictor of post-operative strength. From a clinical perspective, our work indicates that clinicians should utilize therapies targeting both quadriceps activation and strength prior to ACL reconstruction in order to maximize these factors post-ACL reconstruction, as pre-operative activation and strength are related to post-operative activation and strength, respectively at return-to-activity.

Purpose: This study aimed to investigate the morphological patterns of remnant anterior cruciate ligament bundles after injury (ACL remnant) on three-dimensional computed tomography (3DCT) and compare them with those on arthroscopy., Methods: Sixty-three patients (33 males and 30 females; mean age 25.2 ± 10.1 years) who had undergone primary ACL reconstruction between March 2011 and December 2012 were included in this study. The average durations between traumas and 3DCT and between 3DCT and surgery were 101.7 ± 87.2 and 38.2 ± 38.7 days, respectively. ACL remnants were classified into four morphological patterns on 3DCT. 3DCT findings were compared with arthroscopic findings with and without probing., Results: The morphological patterns of the ACL remnants on 3DCT were well matched with those on arthroscopy without probing (the concordance rate was 77.8%). However, the concordance rate was reduced to 49.2% when arthroscopic probing was used to confirm the femoral attachment of ACL remnants (p ≤ 0.05)., Conclusions: This study demonstrates that the morphological patterns of ACL remnants on 3DCT were well matched with those on arthroscopy without probing. Therefore, the technique can be useful for preoperative planning of the ACL reconstruction or informed consent to the patients. However, for definitive diagnosis, arthroscopic probing is required., Level of Evidence: IV.

Purpose: Single leg hop for distance is used to inform rehabilitation and return to sport following anterior cruciate ligament reconstruction. However, impairment of landing mechanics may persist after the recommended performance parameter (hop distance) has been met; therefore, alternative methods are required. This study follows the COSMIN guideline to investigate the measurement properties of data from a new instrument (2D TIP). This is a simple motion analysis instrument to assess landing strategy based on more complex biomechanical modelling., Methods: Data collected in the clinical setting from 30 subjects with chronic ACL deficiency (mean 15.5, SD 4.3 months following injury) before and 6 months after ACL reconstruction and a healthy control group were analysed. Reliability and measurement error were calculated using two repeated measures from three independent raters. Construct validity was assessed by hypothesis testing, and known groups validity and responsiveness were defined by differences between groups., Results: The data demonstrate excellent inter-rater (ICC = 0.81-1.00) and intra-rater (ICC = 0.85-1.00) reliability with low measurement error. Of the eight construct validity hypothesis, six were fully and two partially supported. Between-group differences were significant (P < 0.05) supporting the validity and responsiveness hypothesis., Conclusion: 2D TIP is a simple and inexpensive instrument for assessing landing strategy that has demonstrated appropriate reliability, validity and responsiveness in the ACL-injured population. The instrument will now be used to identify altered movement strategies and develop novel rehabilitation interventions that target strategy and performance., Level of Evidence: Prospective diagnostic study, Level II.

Purpose: In this study, magnetic resonance angiography (MRA) was performed in the early phase after anterior cruciate ligament (ACL) reconstruction to analyse the changes in nutrient blood vessels and blood flow to the femoral and tibial tunnels and the intraosseous tendon grafts., Methods: The subjects were 30 patients who underwent single-bundle ACL reconstruction with an autogenous hamstring tendon. MRA was performed at 2, 3, and 6 months postoperatively (n = 10 at each time point). The mean overall signal-to-noise ratios (SNRs) in the tunnel regions and in the region of the tendon graft were compared in each femur and tibia., Results: Blood vessels from arteries reached the femoral and tibial tunnels 2 months postoperatively. The tunnel walls showed high signal intensity, while the intraosseous tendon grafts had lower intensity. SNRs showed significant differences between the femoral and tibial tunnels overall and the intraosseous tendon grafts. At 3 and 6 months postoperatively, the signal intensity of the tunnel walls was decreased significantly, while that of the intraosseous tendon grafts was also decreased, but not significantly. At these times, the SNRs of the femoral and tibial tunnels did not differ significantly, both overall and in the region of the intraosseous tendon grafts., Conclusion: Revascularization around the femoral and tibial tunnels occurred at 2 months postoperatively, with blood flow subsequently decreasing over time until 6 months. This revascularization may be involved in bone tendon healing and maturation of the tendon graft within the bone tunnels. Evaluations of revascularization by MRA may show the maturation stage of the graft and guide medical rehabilitation., Level of Evidence: IV.

Purpose: Unrealistic patient expectations have been shown to negatively influence patient-reported outcomes in orthopaedic surgery. Knowledge about patient expectations is important to associate preoperative expectations with the reasonable outcome of a specific procedure. The purpose of this study was to prospectively analyse and to compare patient expectations of primary and revision anterior cruciate ligament reconstruction (ACLR) and to assess the factors associated with patient expectations., Methods: Preoperative expectations of 181 consecutive patients undergoing ACLR were assessed prospectively using a 5-item questionnaire. Primary ACLR (P-ACLR) was performed in 133 patients (73%), whereas 48 patients (27%) underwent revision ACLR (R-ACLR). The questionnaire assessed the expectation of the overall condition of the knee joint, return to sports, instability, pain, and risk of osteoarthritis., Results: All patients expected a normal (38%) or nearly normal (62%) condition of the knee joint. Return to sports at the same level was expected by 91%. With regard to instability (pain), no instability (pain) independent of the activity level was expected by 77% (58%). No or only a slightly increased risk of the development of osteoarthritis was expected by 98%. The R-ACLR group showed a significantly lower expectation of the overall condition (p = 0.001), return to sports (p < 0.001), and pain (p = 0.002). No statistically significant difference was found between female and male patients (n.s.). In the P-ACLR group, patients with a history of previous knee surgery showed inferior expectations of return to sports (p = 0.015) and risk of osteoarthritis (p = 0.011). Age, number of previous knee surgeries, and pre-injury sports level significantly influenced patient expectations., Conclusions: Overall, patient expectations of ACL reconstruction are high. Patients undergoing revision ACL reconstruction have lower but still demanding expectations. Younger patients, patients without a history of knee surgery, and highly active patients have higher expectations. Explicit patient information about realistic goals of ACL reconstruction seems to be necessary in order to prevent postoperative dissatisfaction despite a successful operation in the surgeons' point of view., Level of Evidence: Prospective case series, Level IV.

Purpose: The purpose of this study was to assess activation patterns of medial (MH) versus lateral (LH) hamstrings in female athletes who had undergone ACL reconstruction (ACLR) using a hamstrings-graft during single-limb functional testing., Methods: Eighteen athletes (1-6 years since ACLR) and 18 healthy controls were recruited from the Icelandic women's top divisions in football, handball, and basketball. Activation of the MH and LH was monitored bilaterally using surface electromyography. Peak activation of the normalized signal was identified for two phases of the single-limb crossover (SLC) hop test and performance (distance jumped) registered. Self-reported knee symptoms and function were evaluated with the Knee injury and Osteoarthritis Outcome Score (KOOS). A repeated measures general linear model was used for main statistical data analyses, comparing variables of interests between limbs (within-subjects factor) and between groups., Results: ACLR athletes had worse KOOS-symptoms scores (p < 0.05) than controls, while hop distance was equal. Overall, MH and LH muscle activation levels differed between the two phases of the SLC hop test (p < 0.05). Moreover, inter-limb differences in MH and LH activity were identified between groups (p < 0.05), mainly explained by greater LH than MH activation in the uninjured limb of ACLR athletes., Conclusion: One to 6 years after ACLR, female athletes performed on par with uninjured controls, but demonstrated inter-limb differences in muscle activation patterns of the hamstrings that were not evident in controls. This may be an important factor to consider during postsurgical rehabilitation in order to lower the risk of a second injury., Level of Evidence: III.

Purpose: The purpose of this study was to identify the impact of tibial reamer size and placement on the position of femoral tunnel placement via a transtibial approach for anterior cruciate ligament (ACL) reconstruction., Methods: Eight cadaveric knee specimens were fixed to a stationary table at 90° of flexion and neutral rotation. After removing the anterior capsule and patella, native joint anatomy was recorded with a digitizer (MicroScribe™; CNC Services, Amherst, VA) accurate to 0.05 mm. Tibial and femoral tunnels were drilled via a transtibial ACLR technique using the optimal tibial starting point described by Piasecki et al. On the tibial side, tunnels were drilled progressively with 6-, 7-, 8-, 9-, 10-, and 11-mm reamers. After each reaming, a beath pin was placed in the posterior aspect of the tibial tunnel, positioned relative to the native anatomic ACL femoral footprint, and digitized. Rhino software (McNeel, Seattle, WA) was used to geometrically determine the center of the native femoral footprint and measure in millimeters the relationship of this point with the femoral position achieved using a 7-mm offset femoral guide with each tibial tunnel size. The surface areas of each tibial and femoral insertion were measured using the insertional periphery data recorded with the digitizer. Statistical analysis of continuous variable data was performed with t tests; P values below 0.05 were deemed significant., Results: The center of the femoral ACL footprint was reached with a 9-mm tibial tunnel in six knees, and with an 8-mm tunnel in two knees. A 6- or 7-mm tibial tunnel did not allow for anatomic positioning in any specimen, with femoral positioning significantly more superior than that achieved with a 9-, 10-, or 11-mm tibial tunnel (P < 0.01). The 6- and 7-mm tunnels produced errors of 4.6 ± 1.6 and 2.9 ± 0.5 mm, respectively. After use of the 11-mm tibial reamer, the average tibial tunnel length was 32.1 ± 2.6 mm., Conclusions: Limitations of a transtibial ACLR technique may result in non-anatomic femoral tunnel placement with tibial tunnel sizes smaller than 9 mm. However, tibial tunnels placed in the proximal entry position with at least a 9-mm tunnel size allowed anatomic femoral tunnel placement via a transtibial approach.