A Torn ACL Mapping in Knee MRI Images Using Deep Convolution Neural Network with Inception-v3

In order to solve the problem of the difference in the diagnostic effect of different sequences of magnetic resonance imaging (MRI) examinations for anterior and posterior cruciate ligament injuries, the author proposes an MRI rehabilitation method to relieve anterior cruciate ligament injury in dancers. This method retrospectively analyzed the clinical data of 60 patients with knee anterior and posterior cruciate ligament injuries in our hospital, and all patients were diagnosed with knee anterior and posterior cruciate ligament injuries. All patients underwent MRI 3D sequence and 2D sequence examination successively to compare anatomical measurements. This study aimed at comparing the measurements of the posterior cruciate ligament (PCL) and anterior cruciate ligament (ACL) between the two examination sequences; comparing the diagnosis; comparing the grading and judgment of the anterior and posterior cruciate ligament injuries of the knee joint between the two inspection sequences; and comparing the diagnostic coincidence rates of the two examination sequences in the complete tear of the anterior and posterior cruciate ligaments of the knee. Experimental results show that, in terms of PCL and ACL, the angle, thickness, and length of two-dimensional MRI examination were significantly different from those of MRI examination and anatomical measurement (P < 0.05); for PCL and ACL, the angle, thickness, and length of 3D MRI were not significantly different from anatomical measurements (P > 0.05). The diagnostic accuracy of 2D MRI was 83.33%, which was lower than 95.00% of 3D MRI (P < 0.05). There was no significant difference in the grading of anterior and posterior cruciate ligament injuries between the two examination sequences (P > 0.05). The diagnostic coincidence rates of 3D MRI and 2D MRI for complete tear of the anterior and posterior cruciate ligaments were 95.55% and 80.00%, respectively (P < 0.05). In conclusion, three-dimensional MRI examination can obtain higher diagnostic value for patients with knee joint anterior and posterior cruciate ligament injury.

Objectives:Fractures of the tibial spine (TSF) occur as a result of an anterior cruciate ligament (ACL) avulsion fracture from the proximal tibia. Both TSF and ACL injuries are associated with concomitant intraarticular pathology seen on Magnetic Resonance Imaging (MRI) and intraoperatively. In addition, posterior tibial slope (PTS) has been identified as a potential risk factor for ACL injury. The purpose of this study is to describe concomitant injuries seen on MRI and at time of surgery for TSF and ACL patients, and to characterize posterior tibial slope in patients who sustain these injuries. Our hypothesis is that ACL and TSF injuries have similar rates of meniscal injury, and that posterior tibial slope is increased in patients with TSF and ACL injuries compared to matched controls.Methods:Utilizing an institutional review board approved retrospective study, we identified patients under 18 years of age who underwent arthroscopic management of a TSF from December 31st 2008 to December 31st 2021. Exclusion criteria were patients with a concomitant lower extremity fracture or posterior cruciate ligament injuries, poor imaging quality, and incomplete medical records. TSF patients were compared to an age and gender matched cohort of patients who underwent surgery for a mid- substance ACL rupture, and a similar control group. We evaluated concomitant injuries based on radiology and operative reports and measured PTS on radiographs as well as medial (MTS) and lateral (LTS) posterior slope on MRI for all groups. We compared tibial slope amongst the groups using a one- way analysis of variance test, and the Fisher’s exact test was used to compare concomitant injuries between the ACL and TSF groups.Results:85 TSF patients met inclusion criteria, of which 44 had an MRI. There were 41 patients in the ACL group and 44 in the control group. The average age was 11.8 years. Concomitant injuries were identified on MRI in 59.1% of TSF and 51.2% of ACL patients, and intraoperatively in 36.5% of TSF and 37% of ACL patients. The most common concomitant injury was lateral meniscus tears. There was no significant differnce between the TSF and ACL groups in terms of lateral meniscus tears seen on MRI (29.5% TSF vs 31.7 ACL, p=1.0) and seen on arthroscopy (18.2% TSF vs 31.7% ACL, p=0.21). Similarly there were no significant differences between the TSF and ACL group in terms of medial meniscus tears seen on MRI (13.6% vs 17.1%, p = 0.77) and on arthroscopy (9% vs 5%, p=0.19). There was a significant difference between groups when comparing the pivot-shift bone bruise pattern seen on MRI (63.6% TSF vs 90.2% ACL, P= <0.01). There was significantly increased radiographic PTS in the TSF and ACL groups (Radiographs 8.7°+/-3.0° TSF vs 9.5°+/-3.3° ACL vs 6.6°+/-2.3° Control, p= <0.01). This was also seen in the MTS mesured on MRI (MTS 5.3°+/-3.1° TSF vs 4.9°+/-2.7° ACL vs 3.7°+/-2.3° Control p= 0.02). There was no significant difference in LTS between TSF and Controls, but there was between ACL and Controls (LTS 4.1°+/-2.8° TSF vs 6.8°+/- 3.9°ACL vs 4.3°+/- 2.3° Control, p=<0.01).Conclusions:This study is the first to depict tibial slope and bone contusion patterns seen in tibial spine injuries, as well as compare rates of meniscal injury and tibial slope between ACL and control patients. Posterior tibial slope is significantly increased in patients who sustain a TSF or ACL injury, suggesting that it may be a risk factor for injury. Similar rates of concomitant meniscal pathology are seen in both TSF and ACL injured patients, which may reflect similar mechanisms of injury. This also highlights that care must be taken to evaluate for additional pathology when treating TSF and ACL injuries. Future study is needed to determine the role, if any, that tibial slope plays in tibial spine fractures as well as to determine if intraarticular pathology identified on MRI influences longer term patient outcomes.

KeywordsAnterior cruciate ligament; Tear; Meniscus; Rupture; PatternsIntroductionAnterior cruciate ligament (ACL), as a primary stabilizing structure of knee is the most common disrupted ligament in acute trauma in the US every year [1,2]. On the other hand, the menisci play a crucial role in the dynamics of the knee. Their shape, attachment, and material properties contribute substantially to joint alignment and load transmission by distributing both tensile and compressive forces. Damage to the menisci can influence proprioception, stability, and mobility of the knee [3,4]. Risk factors for meniscal tears include prolonged or repeated deep knee bending, obesity, and sports [5]. Acute injury, as seen in alpine sports, involves complex dynamics, which can damage singular or multiple tissue structures of the knee [5,6]. Meniscal tears are typically thought to be initiated by coupled compression and twisting movements [7,8] which can accompany high-energy maneuvers such as cutting, jumping, and landing during sporting events [9].Meniscal injuries commonly occur in conjunction with ACL tears. A numerous studies have examined the occurrence of these injuries, with their presence being reported as 16% to 82% in knees with acute ligament tears and as high as 96% in knees with chronic ligament tears [10-14]. Magnetic resonance imaging (MRI) is valuable tool, preferred than diagnostic arthroscopy in most patients with ligamentous and meniscal tears because it avoids the surgical risks of arthroscopy, with better accuracy in medial and lateral meniscus and ACL [15].Lateral meniscal tears (LMTs) occur slightly more frequently than medial meniscal tears (MMTs) in knees with acute ACL injuries, 56% lateral versus 44% medial. [10,12]. MMTs however, are more common in chronic ACL deficiency [10,12,14]. This difference in tear occurrence is usually attributed to the anatomic and functional differences that exist between the two menisci, especially in the ACL deficient knee, the lateral meniscus relatively loosely attached to the tibial plateau which allows it to be quite mobile, whereas the medial meniscus, is firmly attached to the tibia, especially at the posterior horn [12,16,17]. This firm attachment allows the medial meniscus to act as a knee stabilizer, a significant restraint to anterior tibial translation in the ACL deficient knee [18-21]. The loss of ACL function increases tibial translation, allowing the meniscus to “engage” the femoral condyle and act as a wedge against the tibia [22,23], while others have suggested that mechanical trauma causes the MMTs in this setting [12,18,20]. Several studies have explored the relationship between ACL injury and meniscal tear [24-30]. Some showed preponderance of the LMTs in the acute setting and in osteoarthritis [24,25], others suggested the MMTs especially in acute reconstructions [26-29].This study was conducted to determine the patterns of meniscus damage associated with ACL rupture and identify the commonest type of meniscus damage in our population that is associated with ACL tear.MethodsMedical records of patients with ACL rupture covering a period of 16 years (January 1996 to December 2012) seen at the author’s institute were retrospectively reviewed. The collected data included the presence or absence of meniscal tear, the type of meniscal tear diagnosed by MRI or arthroscopy, the time of the initial ACL injury and the time of meniscal tear, the duration between ACL rupture and reconstruction surgery, age, gender, mode of injury and level of sports activity performed, height, weight.BMI is calculated according to the Patient’s height and weight, patient is considered obese if the BMI is above 30 according to the World Health Organization [31].Sports level was classified as: professional athletes: (practicing a sport activity as a job, e.g. member of a team), recreational Athlete (considered a person, who is practicing a sport activity that is involving running and pivotal movements at least once in a week not professionally), non athlete (a person who is not practicing any kind of sport), patients with no clear statement regarding their level of sport are considered as missing data.Mode of Injury is classified as direct (Injury was caused be a direct trauma to the patent, e.g. hit by another player, felt on his knees or road traffic accident) or non direct (Injury was caused without trauma, e.g. over rotating the knee while exercising).Patients who were diagnosed with ACL rupture using MRI within 3 months of the injury, underwent primary arthroscopic ACL reconstruction at our institution and found to have meniscal damage diagnosed by MRI or arthroscopy were included in the study. Patients who had a chronic ACL tear or had undergone prior ipsilateral knee arthroscopy or surgery, those with osteoarthritis, with rheumatoid arthritis and patients who had undergone ACL rupture revision were excluded from the study. All images were obtained by routine knee MRI.Types of Meniscal Tears were obtained from the reports of the MRI and Arthroscopy and were classified as (longitudinal, Degenerative, flap, radial, complex) as according to Tandogan et al. [32], De Smet [33].Data collected were entered and coded systematically into a Microsoft Excel worksheet and were imported to a Predictive analysis software (PASW) program version 18 (SPSS, IBM, Chicago, Illinois, USA). Oneway analysis of variation (ANOVA) was used to compare means between the three groups (LMTs, MMTs and both). Pearson correlation was conducted to determine the relationship between the outcome variables (age, gender and sport levels). Independent sample t -test was done to identify differences between the mean values of continuous variables. Chi square test was done to determine associations between categorical variables. A test result considered statistically significant if p< 0.05.ResultsA total of 294 patients satisfied the inclusion criteria of the current study from 1996 to 2012. Of these patients, 175 (59.5%) had MMTs, 91 (31%) had LMTs and 28 patients (9.5%) with both MMT and LMT (Table 1).Table 1: Demographic characteristics of all patients with ACL rupture with meniscus injury. Variables Age in years, mean (SD)27.98 (6.8)Weight in kg, mean (SD)80.80 (17.1)Height in cm, mean (SD)170.73 (7.7)BMI in kg/cm2, mean (SD)27.68 (5.6)Mode of injury Direct injury, n (%)125 (42.5)Non-direct injury, n (%)169 (57.4)Sports level Professional athletes, n (%)5 (1.7)Recreational athletes, n (%)196 (66.7)Non-athlete, n (%)28 (9.5)No available data, n (%)65 (22.1) Patients who had MMTs were significantly older (29.10 ± 7.0 years) compared to lateral (26.24 ± 5.9 years) and both (26.61 ± 6.7 years), p=0.002. There were no significant differences in the height, weight, and BMI, level of sport and mode of injury in between the three groups (MMTs, LMTs and both) (Table 2). Types of meniscal tears are shown in Table 3.Table 2: Comparison between MMT, LMT and both in 294 patients who hadACL tear. VariablesMMTn=175LMTn=91Bothn=28 p valuesAge in years, mean (SD)29.10 (7.0)26.24 (5.9)26.61 (6.7)0.002^Weight in kg. mean (SD)82.38 (17.5)79.14 (16.4)76.87 (16.3)0.165^Height in cm, mean (SD)170.40 (8.1)171.42 (6.6)170.49 (8.1)0.602^BMI, mean (SD)28.34 (5.6)26.83 (5.6)26.43 (5.2)0.062^Obesity, n (%)56 (32.0)22 (24.2)7 (25.0)0.294*Type of ACL tear Direct ACL tear, n (%)68 (38.9)32 (35.2)9 (32.1)0.425*Indirect ACL tear, n (%)65 (37.1)30 (33.0)8 (28.6)Level of sports Recreational athlete, n (%)105 (60.0)67 (73.6)22 (78.6)0.144*Professional athlete, n (%)3 (1.7)2 (2.2)1 (3.6)Note: ^ by ANOVA, * by Chi-square test Table 3: Types of meniscal tears by MRI & Arthroscopy. Types of Meniscal TearsMedialLateralTotalLongitudinal Tears152(75%)86(72%)238(74%)Degenerative Tears16(8%)10(8%)26(26%)Radical Tears8(4%)9(7%)17(5%)Complex Tears6(3%)2(2%)8(2.5%)FLAP6(3%)5(4%)11(3.5%)N/A15(7%)7(7%)22(7%)Total203119322DiscussionIn our study, the patients who had medial meniscal tearing were significantly older than those who had only lateral meniscal tear, and those who had both medial and lateral meniscal tears. No such relationship was significant between age and lateral meniscal tear. Our findings are in concordance with the findings of the study that was conducted in Turkey by Tandogan et al. [32], which showed preponderant injury to the medial meniscus than the lateral meniscus, they also found that the mean age of the patients with medial meniscal tears was 27.0 ± 7.6 years, significantly older than those who had no medial meniscal tearing (25.4 ± 6.7 years). Our patient’s mean age who had medial meniscal tearing was 29.10 ± 7.0 years, significantly older than 26.61 ± 6.7 years in those who did not have medial meniscal tearing. Sports level was not significantly correlated to the parameters we have studied or to the site of meniscal tear. This is probably because most of our patients (66.8%) were just recreational athletes.Our study was in contrast to the findings of Bellabarba et al. [10] ,Thompson et al. [12], Melissa [34] wherein they found that LMTs are more frequently encountered than MMTs, and that MMTs on the other hand are more common in chronic injuries. Our study showed more frequent MMTs than LMTs, of patients with acute ACL injuries. Again, this is probably due to the older age of our patients, which was significantly correlated with MMTs.Obesity, Mechanism of injury, Sport level as a risk factors of meniscal tear didn’t show any significance in determining a common pattern, which goes with the same results that was found in Kluczynski et al. [34] where different risk factors have been examined prospectively to see their effect on meniscal tears and chondral changes.The sensitivity of MRI in detecting meniscal pathology has been proven in several studies [10]. However, Oei in 2003 [35] pointed out the low sensitivity of MRI in detecting lateral meniscal pathology compared to detecting medial meniscal pathology with a sensitivity difference by as much as 14% (93.3% versus 79.3%), in an adult population, more so in the presence of ACL tears [36]. This window would probably explain the differences between the frequencies of LMTs and MMTs, more so in our findings, another point which could also explain our findings; is the common presentation of knee varus malalignment in Saudi population. In a comparison study between Saudi Arabian and Canadian cohorts by the same group, it was clearly found that in knee osteoarthritis patients Saudis had more varus alignment, showed by the Hip-Knee-Ankle angle parameter used to diagnose knee alignment disorders [37].A study addressing the Knee alignment in the Saudi Population Comparing the means of Tibiofemoral angle (TFA) of different age groups in Saudi population to those of corresponding age groups in Japanese and Australian Caucasians showed a statistically significant lower TFA difference in all age groups. Comparison of the means of TFA of different age groups in Saudi population to those of corresponding age groups in Japanese and Australian Caucasians showed a statistically significant difference in all age groups, also Comparison of the means of TFA of Saudi males and females to those of Europeans, Chinese and American Caucasians showed a significant difference from all of them [38].Genuvarus can result in added contact stresses on the medial compartment of the knee and possibly lead to accelerated wear and damage to the articular cartilage.Another explanation for the significant association of older age to MMTs is the association of the medial meniscus posterior horn with severity of the chondral lesion and arthritic changes according to the K-L radiographic score. There is usually accompanied chondral damage in MMTs [39].Secondary medial meniscal tears are considered as the main reason of osteoarthritis followed by ACL deficiency [40]. The aim of this study is to alert the surgeons about the existence of this common finding in order to decrease future osteoarthritis. There were a few limitations in the study mainly because of its retrospective nature; a lot of the Patient’s X-rays were not found in order to study the alignment of the knees. In addition we were not able to obtain detailed information about the chondral lesions in the MRI reports to augment our significant findings of MMTs among our older-aged population.ConclusionThe higher occurrence of medial meniscal tear in acute anterior cruciate tears could be attributed to the age related arthritic changes as well as to the common varus deformity in our population; this finding should be considered by the surgeons in order to decrease future osteoarthritis.ReferencesGriffin LY, Agel J, Albohm MJ, Arendt EA, Dick RW, et al. (2000) Noncontact anterior cruciate ligament injuries: Risk factors and prevention strategies. J Am Acad Orthop Surg 8: 141-150. Grindstaff TL, Hammill RR, Tuzson AE, Hertel J (2006) Neuromuscular control training programs and noncontact anterior cruciate ligament injury rates in female athletes: A numbers-needed to treat analysis. J Athl Train 41: 450-456. Aagaard H, Verdonk R (1999) Function of the normal meniscus and consequences of meniscal resection. Scand J Med Sci Sports 9: 134-140.Jerosch J, Prymka M, Castro W (1996) Proprioception of knee joints with a lesion of the medial meniscus. Acta Orthop Belg 62: 41-45.Baker P, Coggon D, Reading I, Barrett D, McLaren M, et al. (2002) Sports injury, occupational physical activity, joint laxity, and meniscal damage. J Rheumatol 29: 557-563.Renstrom P (1994) Clinical practice of sports injury prevention and care. Olympic encyclopedia of sports medicine. Oxford, London, Edinburgh, Boston, Melbourne, Berlin, Paris, Vienna: Blackwell Scientific Publications, LTD.Muellner T, Nikolic A, Vecsei V (1999) Recommendations for the diagnosis of traumatic meniscal injuries in athletes. Sports Med 27: 337-345. Slocum DB, Larson RL (1968) Rotatory instability of the knee: Its pathogenesis and a clinical test to demonstrate its presence. J Bone Joint Surg Am 50: 211-225.Muellner T, Weinstabl R, Schabus R, Vécsei V, Kainberger F, et al. (1997) The diagnosis of meniscal tears in athletes: A comparison of clinical and magnetic resonance imaging investigations. Am J Sports Med 25: 7-12. Bellabarba C, Bush-Joseph CA, Bach BR Jr (1997) Patterns of meniscal injury in the anterior cruciate-deficient knee: A review of the literature. Am J Orthop 26: 18-23.Yoon KH, Yoo JH, Kim KI (2011) Bone contusion and associated meniscal and medial collateral ligament injury in patients with anterior cruciate ligament rupture. J Bone Joint Surg Am 93: 1510-1518.Thompson WO, Fu FH (1993) The meniscus in the cruciate-deficient knee. Clin Sports Med 12: 771-796. Panisset JC, Duraffour H, Vasconcelos W, Colombet P, Javois C, et al. (2008) Clinical, radiological and arthroscopic analysis of the ACL tear. A prospective study of 418 cases. Rev Chir Orthop Reparatrice Appar Mot 94: 362-368.Wickiewicz TL (1990) Meniscal injuries in the cruciate-deficient knee. Clin Sports Med 9: 681-694. Crawford R, Walley G, Bridgman S, Maffulli N (2007) Magnetic resonance imaging versus arthroscopy in the diagnosis of knee pathology concentrating on meniscal lesions and ACL tears: a systematic review. Br Med Bull 84: 5-23.Villegas DF, Hansen TA, Liu DF, Donahue TL (2008) A quantitative study of the microstructure and biochemistry of the medial meniscal horn attachments. Ann Biomed Eng 36: 123-131.Kan A, Oshida M, Oshida S, Imada M, Nakagawa T, et al. (2010) Anatomical significance of a posterior horn of medial meniscus: The relationship between its radial tear and cartilage degradation of joint surface. Sports Med Arthrosc Rehabil Ther Technol 2:1.Allen CR, Wong EK, Livesay GA, Sakane M, Fu FH, et al. (2000) Importance of the medial meniscus in the anterior cruciate ligament-deficient knee. J Orthop Res 18: 109-115. Hsieh H-H, Walker PS (1976) Stabilizing mechanisms of the loaded and unloaded knee joint. J Bone Joint Surg Am 58: 87-93. Indelicato PA, Bittar ES (1985) A perspective of lesions associated with ACL insufficiency of the knee: A review of 100 cases. Clin Orthop Relat Res 198: 77-80.Markolf KL, Kochan A, Amstutz HC (1984) Measurement of knee stiffness and laxity in patients with documented absence of the anterior cruciate ligament. J Bone Joint Surg Am 66: 242-252. Levy IM, Torzilli PA, Warren RF (1982) The effect of medial meniscectomy on anterior-posterior motion of the knee. J Bone Joint Surg Am 64: 883-888. Sullivan D, Levy IM, Sheskier S, Torzilli PA, Warren RF, et al. (1984) Medial restraints to anteriorposterior motion of the knee. J Bone Joint Surg Am 66: 930-936. Cipolla M, Scala A, Gianni E, Puddu G (1995) Different patterns of meniscal tears in acute anterior cruciate ligament (ACL) ruptures and in chronic ACL-deficient knees. Classification, staging and timing of treatment. Knee Surg Sports Traumatol Arthrosc 3: 130-134.Nikolic DK (1998) Lateral meniscal tears and their evolution in acute injuries of the anterior cruciate ligament of the knee. Arthroscopic analysis. Knee Surg Sports Traumatol Arthrosc 6: 26-30. Cerabona F, Sherman MF, Bonamo JR, Sklar J (1988) Patterns of meniscal injury with acute anterior cruciate ligament tears. Am J Sports Med 16:603-609. Keene GC, Bickerstaff D, Rae PJ, Paterson RS (1993) The natural history of meniscal tears in anterior cruciate insufficiency. Am J Sports Med 21:672-679.Paletta GA, Levine DS, O’Brien SJ, Wickiewicz TL, Warren RF (1992) Patterns of meniscal injury associated with acute anterior cruciate ligament injury in skiers. Am J Sports Med 20: 542-547.Smith JP III, Barrett GR (2001) Medial and lateral meniscal tear patterns in anterior cruciate ligament deficient knees. Am J Sports Med 29: 415-419. Kaeding CC, Pedroza AD, Parker RD, Spindler KP, McCarty EC, et al. (2005) Intra-articular findings in the reconstructed multiligament injured knee. Arthroscopy 21: 424-430. WHO (2000) Obesity: Preventing and Managing the Global Epidemic. Report of a WHO consultation. World Health Organ Tech Rep Ser. Tandogan RN, Taşer O, Kayaalp A, Taşkiran E, Pinar H, et al. (2004) Analysis of meniscal and chondral lesions accompanying anterior cruciate ligament tears: relationship with age, time form injury, and level of sport. Knee Surg Sports Traumatol Arthrosc 12: 262-270.De Smet AA (2012) How I diagnose meniscal tears on knee MRI. AJR Am J Roentgenol 199: 481-499. Kluczynski MA, Marzo JM, Bisson LJ (2013) Factors Associated With Meniscal Tears and Chondral Lesions in Patients Undergoing Anterior Cruciate Ligament Reconstruction: A Prospective Study Am J Sports Med 41: 2759-2765.Oei EH, Nikken JJ, Verstijnen AC, Ginai AZ, Myriam Hunink MG (2003) MR imaging of the menisci and cruciate ligaments: a systematic review. Radiology 226: 837-848.De Smet AA, Mukherjee R (2008) Clinical, MRI, and arthroscopic findings associated with failure to diagnose a lateral meniscal tear on knee MRI. AJR Am J Roentgenol 190: 22-26.Cooke TD, Harrison L, Khan B, Scudamore A, Chaudhary MA (2002) Analysis of limb alignment in the pathogenesis of osteoarthritis: a comparison of Saudi Arabian and Canadian cases. Rheumatol Int 22: 160-164.El Fouhil AF, Khoshhal KI, Al-Nakshabandi NA, Al-Boukai AA, Atteya M (2011) Normal knee angles in the adult Saudi population. Saudi Med J 32: 1143-1148.Ozkoc G, Circi E, Gonc U, Irgit K, Pourbagher A, et al. (2008) Radial tears in the root of the posterior horn of the medial meniscus. Knee Surg Sports Traumatol Arthrosc 16: 849-854.Lohmander LS, Englund PM, Dahl LL, Roos EM (2007) The long-term consequence of anterior cruciate ligament and meniscus injuries: Osteoarthritis. Am J Sports Med 35: 1756-1769.

Reconstruction of the anterior cruciate ligament (ACL) is a common surgical procedure with an estimated 50,000 procedures in the US annually. Injury of the ACL often requires costly treatment, extensive rehabilitation, and results in early osteoarthritis. While ACL ruptures occur secondary to a complex interplay of multiple variables, a number of risk factors have been identified that increase risk of ACL rupture. We will analyze a variety of identified risk factors including anatomic, neuromuscular control, hormonal, genetic, and external variables. In terms of intrinsic risk factors, multiple recent studies have identified neuromuscular risk factors that put the ACL at risk for injury. These studies show differences in neuromuscular control of knee joint mechanics, hamstring muscle strength and core stability in patients who sustain ACL injury. Anatomical variants between individuals, genders and races have also been implicated as risk factors for ACL injury. These risk factors include femoral intercondylar notch width, tibial slope geometry, ACL dimensions, and generalized ligamentous laxity. Studies have sought to evaluate the interactions between absolute femoral notch width, notch width index, and intercondylar notch shape and how these factors relate to ACL injury risk. Postulating that an increased anterior directed shear force on the tibia correlates with higher incidence of ACL injury, studies have identified an increased posterior inferior directed tibial slope and shallow medial depth of the tibial plateau, as significant risk factors for ACL injury. Newer research suggests that meniscal geometry factors into this equation as well. Other studies have suggested that decreased ACL volume is a contributing factor, while further studies propose that ACL injury risk can be predicted as a factor of generalized joint laxity. Lastly, prior ACL injury and reconstruction have been implicated as risk factors for future knee injury. Patients undergoing ACL reconstruction are at higher risk for contralateral ACL injury and ACL rerupture post reconstruction compared to individuals without prior ACL injury. Additionally, hormonal and genetic factors have been connected to ACL injury. After estrogen and progesterone receptor sites were found on the ACL, multiple studies have analyzed hormone levels and ACL rupture risk. Overall, the results of these studies are varied and controversial, but suggest an increased risk in the pre ovulatory menstrual cycle phase. Genetic studies have shown specific mutations that place patients at risk for ACL injury and other tendon injury. Also, a study has shown that patients with an ACL rupture were more than 4 times as likely to have a relative with history of ligament injury.

An Increased Lateral Femoral Condyle Ratio in Addition to Increased Posterior Tibial Slope and Narrower Notch Index Is a Risk Factor for Female Anterior Cruciate Ligament Injury

Understanding the biomechanical risk factors for noncontact anterior cruciate ligament (ACL) injury can inform machine learning models, aid in prevention strategies, and guide rehabilitation protocols, reducing the incidence and burden of these injuries in both athletes and the general population. To determine the biomechanical risk factors associated with noncontact ACL injury and increased knee loading. Systematic review; Level of evidence, 4. A literature search was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Randomized, cohort, case-control, and cross-sectional studies identifying noncontact biomechanical risk factors for ACL injuries published before May 2023 were included in this review. Excluded were studies focused on contact ACL injuries, those focused on biomechanical risk factors postinjury, and those not published in the English language. The authors highlighted biomechanical risk factors not extensively covered in previous reviews, including the toe-in position, increased contralateral pelvic hike, increased hip internal rotation angle, and specific ankle angles. A quantitative overview of the included studies was conducted, highlighting the frequency of each biomechanical factor reported as potentially related to ACL injury or loading risk. A total of 28 studies (2819 athletes) were selected for analysis. The majority of these studies (22/28) were cross-sectional, primarily assessing ACL load indirectly via knee valgus moment or ground-reaction forces, while case-control and cohort studies focused on ACL injury incidence. Overall, 83% (5/6) of the studies assessing upper body biomechanics found that trunk flexion/extension and perturbations affect ACL loading risk. Of studies assessing hip biomechanics, 83% (10/12) showed increased ACL loading or injury risk with increased hip abduction/internal rotation angles. For the foot and ankle, increased toe-in/toe-out landing in 67% of studies (2/3) demonstrated higher stress on the ACL. Knee biomechanics were associated with increased ACL loading in 100% of the respective studies (5/5), with decreased knee flexion angles leading to increased loading. The data demonstrated that factors associated with increased medial knee alignment, sagittal alignment of the trunk, and decreased lateral trunk flexion reduced both knee loading and ACL injury risk. Targeted prevention and detection strategies addressing high-risk biomechanics may reduce injury incidence, underscoring the need for further research to optimize intervention programs.

PurposeTo compare patients with generalised joint hypermobility (GJH) who sustained a second anterior cruciate ligament (ACL) injury with those who did not sustain a second ACL injury, in terms of muscle strength, psychological response and level of knee‐strenuous activity after primary ACL reconstruction. We hypothesised that patients who sustained a second ACL injury would display similar muscle strength symmetry, report similar psychological response and report greater levels of knee‐strenuous activity compared to patients who did not sustain a second ACL injury.MethodsData from a rehabilitation specific registry were extracted. Patients 15–30 years old with GJH, who sustained a second ACL injury after primary ACL reconstruction were matched 1:2 with patients with GJH who did not sustain a second ACL injury. Outcomes were compared at the 10‐week, 4‐, 8‐ and 12‐month follow‐ups after primary ACL reconstruction. Outcomes comprised limb symmetry index and peak torque relative to body weight for quadriceps and hamstrings muscle groups assessed seated isokinetically with a Biodex. In addition, the questionnaires knee self‐efficacy scale18, ACL‐return to sport after injury scale and Tegner activity scale (Tegner) were analysed. All outcome data were analysed with the independent t‐test, except for the Tegner which was analysed with the Mann–Whitney U‐test.ResultsThirty‐two patients sustained a second ACL injury and were matched with 64 patients who did not. The mean age at time of ACL reconstruction was 19 ± 3 years, and 58 (60%) were female. There were no differences in muscle strength between groups at any follow‐up. At the 8‐month follow‐up, patients with a second ACL injury reported higher on ACL‐return to sport after Injury (65.6 ± 17.9 vs. 53.5 ± 17.3, p = 0.006), and participated in gknee‐strenuous activity (median Tegner 5.0, interquartile range [IQR]: 3.0 versus 4.0, IQR: 4.0, p = 0.046) compared to patients without a second ACL injury.ConclusionPatients with GJH who sustained a second ACL injury reported greater confidence, lower negative emotions, and lesser risk appraisal towards return to sport, and reported greater levels of knee‐strenuous activity at 8 months after primary ACL reconstruction compared to matched patients who did not sustain a second ACL injury. These findings might suggest that patients who report greater psychological readiness to RTS, that is, greater confidence, lower negative emotions and lesser risk appraisal, at 8 months, need more cautious guidance when increasing knee‐strenuous activity.Level of EvidenceLevel IV, cross‐sectional study.

To identify the approaches to management of anterior cruciate ligament (ACL) injury by Canadian orthopedic surgeons. A questionnaire was mailed to 234 physicians randomly chosen from the Canadian Orthopaedic Association directory to obtain the following information: 1) how orthopaedic surgeons diagnose acute hemarthroses; 2) how patients in any of three common ACL injury scenarios would be managed; 3) what variations exist in surgical technique; and 4) how patient variables such as age, gender, and alignment influence the decision-making process. The return rate was 72%, and 56% of respondents were from academic centers. Patients such as those described in the protocol are routinely managed by 80% of the respondents. The diagnosis of acute hemarthrosis is predominantly made by means of clinical examination and radiographs. Magnetic resonance imaging (MRI) is used occasionally by 43% and routinely by 6% of those who responded; arthroscopy is used routinely by 24%. For the competitive athlete with a complete ACL tear, 64% would recommend reconstruction and 33% would recommend bracing and rehabilitation. For reconstruction, 59% would use bone-patellar tendon-bone (B-PT-B) autograft and 32% would use hamstring tendon autograft; 40% would incorporate the ACL stump during reconstruction. Of the respondents, 77% would advocate ACL reconstruction for competitive athletes with chronic ACL injury. Of these, 63% would use B-PT-B autograft and 27% would use hamstring tendons. If bracing and rehabilitation failed, 98% would recommend ACL reconstruction. In ACL reconstruction, synthetic augmentation would be used by 12% in chronic cases and by 16% in acute cases. In making the decision to perform ACL reconstruction, 53% consider limb alignment to be important and 67% consider moderate patellofemoral pain to be important. Seventy-one percent are influenced by patellofemoral pain when choosing a surgical technique, with a trend toward semitendinosis autograft rather than B-PT-B autograft reconstruction. For the 8-year-old child with an acute ACL injury, 63% of the respondents would recommend rehabilitation and bracing. For the 14-year-old, 45% would recommend rehabilitation and bracing and 37% would recommend ACL reconstruction after physeal closure. The results of the survey indicate that, with respect to some of the issues, there is a wide variation in management of acute and chronic ACL injuries among Canadian orthopedic surgeons. Future research and randomized, controlled clinical trials should be directed toward these areas.

Objective: To evaluate the correlation between Magnetic Resonance Imaging (MRI) findings and Arthroscopy in diagnosing anterior cruciate ligament (ACL) injuries, using Arthroscopy as the gold standard. Methodology: This prospective cross-sectional study was conducted at the Department of Orthopedic Surgery, Combined Military Hospital, Rawalpindi, from February to August 2019. Clinical evidence of ACL injury was present in 127 individuals. They had an MRI as well as an arthroscopy. The diagnostic efficacy of MRI for ACL tears was evaluated, and its sensitivity, specificity, PPV, NPV, and accuracy were all calculated. Comparisons between arthroscopic and magnetic resonance imaging (MRI) findings yielded three classifications: True Positive (MRI verified by Arthroscopy), True Negative (both MRI and Arthroscopy negative for ACL injury), and False Positive/False Negative (differences between MRI and Arthroscopy). The arthroscopic inspection and MRI findings were entered into SPSS 23 software for tabulation and analysis. When necessary, both descriptive and inferential statistics were used. Results: The study of statistics Arthroscopy was performed on 127 patients, either for diagnostic or therapeutic purposes. A correlation was found when all the data was analyzed and tabulated. The majority of the patients were males (85.8%) in the second and third decades of life. The sensitivity, specificity, NPV, PPV, and accuracy of MRI in diagnosing ACL injuries were 89.89%, 64.28%, 64.28%, 89.89%, and 84.25%, respectively. Conclusion: MRI is an accurate and non-invasive modality for assessing ACL tears, showing good accuracy and high sensitivity. However, Arthroscopy remains the gold standard for diagnosing ACL injuries.

To describe rupture patterns of partial anterior cruciate ligament (ACL) tears on magnetic resonance (MR) imaging. MR images of 51 patients with a surgically confirmed partial ACL tear were retrospectively and independently interpreted by 2 experienced, blinded radiologists. Using previously described MR criteria, ACLs were categorized as follows: complete tear, partial tear, isolated anteromedial or posterolateral bundle tear, mucoid degeneration or normal ACL. MR interpretations were compared with the arthroscopic results as the standard of reference. Inter- and intraobserver agreements were determined using kappa (к) coefficients. On MR imaging, ACL injuries were categorized as complete tears (16-23%), partial tears (20-47%), mucoid degeneration (12-27%) or normal ACLs (18-23%). Isolated ACL bundle tears were diagnosed on MR in 6% of our patients. Accuracy of MR for the diagnosis of partial ACL tears was 25-53%. Interobserver agreement was moderate (к = 0.48-0.56). Intraobserver agreement was good (к = 0.72-0.76). MR diagnosis of a partial ACL tear is difficult because various tear patterns may be seen. Many partial tears demonstrate MR features that are indistinguishable from complete ACL tear, mucoid ACL degeneration or normal ACL. An isolated ACL bundle tear is infrequently detected on MR images.

The shape and size of the meniscus are closely related to the stability of the knee joint and the anterior cruciate ligament (ACL) injury. Studies have confirmed the correlation between meniscal morphology and isolated ACL injury. To investigate meniscal parameters, including morphological changes, in participants with isolated ACL injury. Cross-sectional study; Level of evidence, 3. This retrospective study, conducted from January to December 2021, compared 70 patients with isolated ACL injury with 70 patients with intact ACL. The meniscal slopes and posterior meniscal angles were measured using magnetic resonance imaging. The meniscal slopes include the slope of the anterior horn of the medial meniscus (SAHMM), slope of the posterior horn of the medial meniscus (SPHMM), slope of the anterior horn of the lateral meniscus (SAHLM), and slope of the posterior horn of the lateral meniscus (SPHLM). The posterior meniscal angles include the posterior base angle of the medial meniscus (PBAMM) and the posterior base angle of the lateral meniscus (PBALM). The receiver operating characteristic (ROC) curve was used to analyze the value of meniscal morphological parameters in judging ACL injury. The SPHMM in participants with ACL injury was greater (mean, 23.24° ± 3.42°) than that in participants without (mean, 21.88° ± 3.35°) (P = .019). The PBAMM of participants with ACL injury was significantly higher than that in participants with intact ACL (mean, 73.78° ± 6.32° vs 67.82° ± 5.88°) (P < .001). The ROC cutoff value for SPHMM was 20.65°, and values greater than this had 81.4% sensitivity and 45.7% specificity for ACL injury. The ROC cutoff value for PBAMM was 73.55°, and values greater than this had 54.3% sensitivity and 84.3% specificity. The authors found a strong association between morphological changes in the SPHMM and ACL injury. Therefore, morphological changes in the meniscus can indicate ACL injury.

Objectives:Anterior cruciate ligament (ACL) tears are one of the most common ligamentous injuries of the knee. While many advances have been made in both surgical technique and rehabilitation protocols, it still remains a very serious athletic injury. In recent years, a few high-profile athletes have returned to an elite sport performance level relatively quickly after ACL reconstruction, but previously published literature suggests otherwise. The purpose of this study is to evaluate a college athlete's perception and understanding of ACL injury and subsequent reconstruction.Methods:During pre-participation physicals, a total of 157 surveys were prospectively administered to athletes at a single NCAA Division II university, all of which were returned. Consent was obtained prior to survey administration. The surveys, consisting of sixteen questions, were designed to evaluate the athletes’ knowledge of ACL injury, anatomy, and recovery from surgery. In addition, basic demographic information was obtained including the participants’ source of ACL knowledge. Statistical analysis is pending.Results:The average age of participants was 20.1 years (Range: 18-23). Football, soccer and baseball were the most represented sports among participants, but a wide variety were present. Of the 157 surveys administered, 106 of participants (68%) knew that the ACL was a ligament. The majority of participants (63%) thought it would take 8-12 months to return to sport after an injury, but 31% said an athlete could return in less than 6 months (Range: 2 to 15 months). On average, the participants thought 64% of athletes could return to play in their sport after an ACL injury and reconstruction, but only 45% could return to their previous level of play. However, several participants (8%) believed greater than 80% of athletes could return to their previous level of play after an ACL reconstruction. Only 11% of respondents knew that a knee brace cannot prevent ACL injury. Most participants (82%) said that if they had an ACL injury they would undergo reconstructive surgery. Only 26% of participants knew that an athlete with an ACL injury was at an increased risk for an injury to their contralateral ACL. Furthermore, about half of the participants (54%) thought that on-field performance would not improve following an ACL injury and reconstruction. The most common source of participants’ knowledge of ACL injury was from a friend or family member (71%). Far fewer participants gained at least some of their knowledge from the internet (32%), television (27%) or their physician/surgeon (29%).Conclusion:This is the first study, to our knowledge, to assess the perceptions of high-level athletes with regards to ACL injury, reconstruction and return to play. This study demonstrates that there is a large amount of variability in college athletes’ perception of ACL injuries. The range of recovery time from surgery was quite large, signifying a knowledge gap among high-level athletes with regard to this very common injury. Orthopaedic surgeons may want to assess and tailor their pre-surgical discussions with a college athlete to the individual's knowledge of ACL injury and reconstructions, so that realistic pre-surgical expectations are set. However, the benefits of this approach warrant further investigation.

Objectives:The incidence of second anterior cruciate ligament (ACL) injury in the first 12 months after ACL reconstruction (ACLR) and return to sport in a young, active population has been reported to be 15 times greater than a previously uninjured cohort. It is unknown if this high relative rate of injury continues beyond the first year after return to sport following ACLR. The tested hypothesis was that the incidence rate of a subsequent ACL injury in the 2 years following ACLR and return to sports would be less than the incidence rate reported within the first 12 months after return to sport, but greater than the ACL injury incidence rate in an uninjured cohort of young athletes.Methods:Seventy-eight subjects who underwent ACLR and were ready to return to a pivoting/cutting sport (RTS) and 47 controls were prospectively enrolled. Each subject was followed for injury and athletic exposure (AE) data for a 24-month period after return to sport. Twenty-three subjects after ACLR and 4 control subjects suffered an ACL injury during this time. Incidence rate ratios (IRR) were calculated to compare the rates (per 1000 athletic exposures [AEs]) of ACL injury in athletes in the ACLR group and control group. For the ACLR group, similar comparisons were conducted for side of injury by sex.Results:The overall incidence rate of a second ACL injury within 24 months after ACLR and RTS (1.39/1000 AE) was nearly 6 times greater (IRR=5.71, 95% CI: 2.0, 22.7, p=0.0003) than healthy control subjects (0.24/1,000 AE). Female ACLR athletes demonstrated 4 times greater rate of injury within 24 months of RTS (IRR=4.51; 95% CI: 1.5-18.2, p=0.0004) than female controls. Within the ACLR group, there was a trend for female subjects to be over two (RR=2.43, 95% CI: 0.8, 8.6) times more likely to suffer a contralateral injury (1.13/1000 AEs) than an ipsilateral injury (0.47/1000 AEs). Overall, 29.5% of athletes suffered a second ACL injury within 24 months of RTS with 20.5% sustaining a contralateral injury and 9.0% incurring an ipsilateral graft re-tear injury. A higher proportion of females (23.7%) suffered a contralateral injury compared to males (10.5%). Conversely, for ipsilateral injuries, the incidence proportion between females (8.5%) and males (10.5%) were found to be similar.Conclusion:These data support the hypothesis that in the 24 months following ACLR and RTS, patients are at greater risk (nearly 6 times) to suffer a subsequent ACL injury compared to young athletes without a history of ACL injury. Additionally, the contralateral limb of female patients appears to be at greatest risk. These 24 month outcome data, analyzed in conjunction with recent 12 month outcome data which noted a 15 times greater risk of ACL injury compared to healthy control subject, indicate that the greatest risk of second ACL injury after ACLR occurs during the initial 12 months after ACLR and RTS than the second year after RTS.

BackgroundNotch volume is associated with anterior cruciate ligament (ACL) injury. Manual tracking of intercondylar notch on MR images is time-consuming and laborious. Deep learning has become a powerful tool for processing medical images. This study aims to develop an MRI segmentation model of intercondylar fossa based on deep learning to automatically measure notch volume, and explore its correlation with ACL injury.MethodsThe MRI data of 363 subjects (311 males and 52 females) with ACL injuries incurred during non-contact sports and 232 subjects (147 males and 85 females) with intact ACL were retrospectively analyzed. Each layer of intercondylar fossa was manually traced by radiologists on axial MR images. Notch volume was then calculated. We constructed an automatic segmentation system based on the architecture of Res-UNet for intercondylar fossa and used dice similarity coefficient (DSC) to compare the performance of segmentation systems by different networks. Unpaired t-test was performed to determine differences in notch volume between ACL-injured and intact groups, and between males and females.ResultsThe DSCs of intercondylar fossa based on different networks were all more than 0.90, and Res-UNet showed the best performance. The notch volume was significantly lower in the ACL-injured group than in the control group (6.12 ± 1.34 cm3 vs. 6.95 ± 1.75 cm3, P < 0.001). Females had lower notch volume than males (5.41 ± 1.30 cm3 vs. 6.76 ± 1.51 cm3, P < 0.001). Males and females who had ACL injuries had smaller notch than those with intact ACL (p < 0.001 and p < 0.005). Men had larger notches than women, regardless of the ACL injuries (p < 0.001).ConclusionUsing a deep neural network to segment intercondylar fossa automatically provides a technical support for the clinical prediction and prevention of ACL injury and re-injury after surgery.

ACL Research Retreat V