Bilateral Anterior Cruciate Ligament Research Articles

Revision ACL reconstruction, but not bilateral ACL reconstruction, is associated with clinically relevant inferior subjective knee function compared with primary ACL reconstruction: A comparative analysis of 6831 patients.

To evaluate and compare the subjective knee function in patients undergoing revision and bilateral anterior cruciate ligament (ACL) reconstruction (ACLR) with those undergoing primary ACLR in a large cohort. Patients without concomitant ligament injuries who underwent primary, revision or bilateral ACLR at the Capio Artro Clinic, Stockholm, Sweden, between 2005 and 2018 were identified. The Knee injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and at 1, 2 and 5 years postoperatively from the Swedish National Knee Ligament Registry. Patients who underwent revision and bilateral ACLR were compared with those who underwent primary ACLR (control group) using Student's t test. A total of 6831 patients (6102 with primary ACLRs, 343 with revision ACLRs and 386 with bilateral ACLRs) were included. Preoperatively, there were significant but nonclinically relevant differences in favour of the revision ACLR group for KOOS Symptoms, Pain, Activities of Daily Living (ADL) and Sport/Rec subscale scores compared with the primary ACLR group. Postoperatively, except for the 1-year Symptoms and ADL subscales, the revision ACLR group reported significantly lower scores on all KOOS subscales than the primary ACLR group, with clinically relevant differences (>8-10 points) for the 1-, 2- and 5-year Sport/Rec and Quality of Life (QOL) subscales. The bilateral ACLR group reported significantly, but not clinically relevant, inferior scores on the 1-year Symptoms and QOL subscales and the 5-year Sport/Rec and QOL subscales compared with the primary ACLR group. Revision ACLR, but not bilateral ACLR, was associated with clinically relevant inferior subjective knee function compared with primary ACLR. It is important to counsel patients regarding their future subjective knee function after repeated ACLR. Compared to primary ACLR, inferior subjective results should be expected after revision ACLR, but not after bilateral ACLR. Level III.

Guided Growth for Correction of Elevated Tibial Posterior Slope in Pediatric ACL Deficiency: A Case Report.

Fourteen-year-old boy, history of autism presented with bilateral knee instability. Imaging revealed bilateral anterior cruciate ligament (ACL) insufficiency, 20° of posterior tibial slope (PTS) on the right and 18° on the left. A guided growth technique using anterior placed tension band plates was used to correct the PTS. At 22 months, the PTS corrected to 5.5° on the right and 6° on the left. The patient's knee stability improved, and he resumed activities at 30 months. Pediatric ACL insufficiency in the setting of elevated PTS can be successfully corrected with a guided growth technique.

Functional outcomes in single stage bilateral ACL reconstruction with a maximum follow up of 10 years

BackgroundBilateral ACL injuries are a rarity and there is no particular consensus on whether this rare problem has to be tackled in stages or in a single stage. There are a few studies and case reports in the literature about the outcomes in single staged bilateral Anterior cruciate ligament reconstruction (ACLR). This study is focused on functional outcomes after a single staged bilateral ACLR, as well as impact of simultaneity of the injury, meniscal tears, notch stenosis and hyperlaxity. Materials and methodsA retrospective study was conducted from 2013 to 2021. Patients with bilateral ACL injury either simultaneous or non simultaneous, with or without meniscal tears were included in this study. Pre operative diagnosis was made both clinically and by MR imaging. All patients underwent a single staged bilateral ACL reconstruction. Pre operative functional scores (IKDC and Lysholm) were taken at admission and patients were examined at regular follow ups. Final functional scores were collected in a phone interview. Results33 patients underwent bilateral ACLR in a single stage during the study period but one patient had revision ACLR in one knee and so was excluded. Of the 32 patients, 25 (78%) had non simultaneous injury and 7 (22%) had a simultaneous injury, meniscus tear was noted in 27 (84.4%), notch stenosis in 19 (59.3%) and hyperlaxity in 12 (37.5%). IKDC and Lysholm scores have improved postoperatively. No statistically significant difference was found with or without simultaneous injury or meniscus tears. ConclusionSingle stage bilateral ACL reconstruction is a safe, reproducible approach to bilateral ACL injuries whether they were simultaneous or non simultaneous or with or without meniscal tears.

Patients with Bilateral ACL Reconstruction (ACLR) have 3x the Rate of Posterior Tibial Slope Greater than 12-Degrees Compared to Unilateral ACLR: MRI and Radiographic Evaluation

Objectives: Increased posterior tibial slope (PTS) is a risk factor for primary anterior cruciate ligament (ACL) tear and graft failure, but PTS has not been well-defined in those who have experienced bilateral ACL injuries. We aimed to compare PTS angles, as well as the rate of elevated PTS (>12° on lateral radiograph; >7° on MRI), between patients who underwent bilateral ACL reconstruction (ACLR) vs unilateral ACLR. A secondary purpose was to examine whether these associations remained consistent on both plain radiographs and MRIs. Methods: We retrospectively identified patients who underwent primary ACLR at our institution from the years 2012 to 2020. Patients with non-simultaneous bilateral ACLR (n=53) were propensity matched to those with unilateral ACLR (n=53) by age, sex, and BMI. Exclusion criteria were: rotated lateral radiographs, inadequate quality MRI, concomitant ligament injury or fracture. Unilateral ACLRs with less than 5-year follow-up were further excluded. Three blinded readers measured PTS on lateral radiographs, while medial (MPTS) and lateral PTS (LPTS) were measured on MRI. Bivariate regression was performed to determine correlation between radiograph and MRI measurements. Results: A final cohort of 106 patients was analyzed (mean age: 27.4 ± 10.5 years, 49.1% male, BMI: 25.5 ± 4.3). PTS in the bilateral ACLR cohort was significantly greater than the unilateral ACLR cohort on radiographs (11.26° vs 10.13°, p=0.044) and LPTS (7.32° vs 6.08°, p=0.012), but not MPTS (4.55° vs 4.17°, p=0.467). The percentage of bilateral patients with radiograph PTS >12° was 41.0%, compared to 13.2% in unilateral cohort (p=0.012). The bilateral cohort had a significantly greater rate of LPTS >7° compared to unilateral patients (53.8% vs 32.1%, p=0.016), but not MPTS (p=0.467). On MRI, LPTS (5.93° ± 3.20°) was significantly greater than MPTS (5.12° ± 2.78°, p<0.001). There was weak correlation between MPTS-radiograph ( R=0.24, p=0.02) and LPTS-radiograph was not significantly correlated ( R=0.03, p=0.810). Conclusions: Patients who underwent bilateral ACLR had significantly greater PTS on radiographs and LPTS on MRI compared to those with unilateral ACLR. The rate of PTS >12° was 3.1x greater among bilateral ACLR compared to unilateral ACLR. PTS measurements on radiographs demonstrated weak-to-negligible correlation with MRI measurements, suggesting future normative PTS values should be reported specific to the imaging modality.

Psychological Readiness to Return to Sport and Return to Sport Rates Are Similar in Patients After Either Bilateral or Unilateral Anterior Cruciate Ligament Reconstruction

To compare psychological readiness to return to sport (RTS), RTS rate, level of return, and time to return between patients who underwent bilateral anterior cruciate ligament reconstruction (ACLR) and those who underwent unilateral ACLR. The electronic medical record at a single academic medical center was queried for patients who underwent ACLR from January 2012 to May 2020. The inclusion criteria were skeletally mature patients who underwent either single or sequential bilateral ACLR and who had undergone either the primary ACLR or second contralateral ACLR at least 2 years earlier. Bilateral ACLRs were matched 1:3 to unilateral reconstructions based on age, sex, and body mass index. Psychological readiness to RTS was assessed using the validated ACL Return to Sport After Injury (ACL-RSI) scale. This, along with time to return and level of RTS, was compared between the 2 cohorts. In total, 170 patients were included, of whom 44 underwent bilateral ACLR and 132 underwent unilateral ACLR. At the time of the first surgical procedure, patients in the unilateral cohort were aged 28.8 ± 9.4 years and those in the bilateral cohort were aged 25.7 ± 9.8 years (P= .06). The average time difference between the first and second surgical procedures was 28.4 ± 22.3 months. There was no difference in psychological readiness to RTS (50.5 in bilateral cohort vs 48.1 in unilateral cohort, P= .66), RTS rate (78.0% in unilateral cohort vs 65.9% in bilateral cohort, P= .16), percentage of return to preinjury sport level (61.2% in unilateral cohort vs 69.0% in bilateral cohort, P= .21), or time to return (41.2± 29.3 weeks in unilateral cohort vs 35.2 ± 23.7 weeks in bilateral cohort, P= .31) between the 2 cohorts. Compared with patients who undergo unilateral ACLR, patients who undergo bilateral ACLR are equally as psychologically ready to RTS, showing equal rates of RTS, time to return, and level of return. Level III, retrospective cohort study.

Poster 340: Return to Sport and Psychological Readiness to Return to Sport in Individuals who Have Undergone Bilateral vs Unilateral ACL Surgeries

Objectives: Prior studies report lower return to preinjury level of sport in patients who undergo bilateral anterior cruciate ligament (ACL) reconstructions compared to unilateral reconstructions, with the most common cited reason being fear of reinjury. The purpose of our investigation was to compare subsequent return rates and psychological readiness to return to sport (RTS) in patients who underwent bilateral versus unilateral ACL reconstructions. Methods: A retrospective review of patients who underwent ACL reconstruction at a single academic institution between 2012-2021 with a minimum of 1-year follow-up was conducted. Patients were divided into bilateral and unilateral cohorts. Those who underwent bilateral ACL reconstruction were matched 1:3 to unilateral reconstruction based on age, sex, BMI, and primary sport. Primary outcomes included return to sport, level of RTS and psychological readiness to RTS, assessed by the validated ACL- Return to Sport after Injury (ACL-RSI) scale. Within the ACL-RSI questionnaire, fear and confidence to return to sport were specifically analyzed. Fear to RTS was measured on a scale of 0-100 with 0 equal to extremely fearful and 100 equal to no fear at all. Confidence to RTS was measured on a scale of 0-100 with 0 equal to not at all confidence and 100 equal to fully confident. Statistical analysis was performed in R studio, with chi-square used for categorical values and two-sided t-test for continuous. Results: One hundred eighty-one patients were included, forty-three bilateral ACL reconstructions and one hundred thirty-eight unilateral. The unilateral cohort included 69 (50.0%) males and 69 (50.0%) females and the bilateral cohort included 22 (51.2%) males and 21 (48.8%) females. Mean age was 26.0 (14-56) in the unilateral cohort and 25.2 (14-50) in the bilateral cohort. Mean BMI was 25 (15.3-39.2) in the unilateral cohort and 28 (15.1-39.7[SM1] ) in the bilateral cohorts (p=.08). The percentage of individuals who returned to sport in the bilateral reconstruction cohort was not significantly different from those who returned in the unilateral cohort (79.6% vs 76.7%, p=0.85). There was no significant difference in psychological readiness to RTS (mean score 52.6 for bilateral and 47.4 for unilateral, p=0.31). There was also no significant difference between the level at which bilateral versus unilateral patients returned to sport. 59.6% unilateral returned to the same or higher level and 60.6% bilateral returned to the same or higher level, p=0.92. There was no significant difference in the reported scale of psychological readiness to return to sport (52.6 for bilateral and 47.4 for unilateral, p=0.31). When asked about fear to RTS, the mean scale response was 42.2 in the unilateral cohort and 46.5 in the bilateral (p=0.45). Conclusions: There is no difference in RTS and level of sport returned to between patients who undergo bilateral ACL reconstructions compared to patients who undergo unilateral ACL reconstructions. Psychological readiness, fear and confidence to return to sport were not different between unilateral and bilateral injuries.

Posterior Tibial Slope in Patients Undergoing Bilateral Versus Unilateral ACL Reconstruction: MRI and Radiographic Analyses

Background: An increased posterior tibial slope (PTS) is a risk factor for primary anterior cruciate ligament (ACL) tears and graft failure, but the PTS has not been well-defined in those who have experienced bilateral ACL injuries. Purpose: The primary aim was to compare the PTS, as well as the rate of an elevated PTS (>12° on lateral radiography; >7° on magnetic resonance imaging [MRI]), between patients who have undergone bilateral ACL reconstruction (ACLR) versus unilateral ACLR. A secondary purpose was to examine whether these associations remained consistent on both plain radiography and MRI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We retrospectively identified patients who underwent primary ACLR at our institution from the years 2012 to 2020. Patients who underwent nonsimultaneous bilateral ACLR (n = 53) were matched to those who underwent unilateral ACLR (n = 53) by age, sex, and body mass index. Exclusion criteria were rotated lateral radiographs, MRI scans of inadequate quality, and concomitant ligament injuries or fractures. Those who had undergone unilateral ACLR with <5-year follow-up were further excluded. There were 3 blinded readers who measured the PTS on lateral radiographs, while the medial PTS (MPTS) and lateral PTS (LPTS) were measured on MRI scans. Bivariate regression was performed to determine the correlation between radiographic and MRI measurements. Results: The PTS on radiography (11.26° vs 10.13°, respectively; P = .044) and the LPTS on MRI (7.32° vs 6.08°, respectively; P = .012) in the bilateral ACLR group were significantly greater than those in the unilateral ACLR group but not the MPTS on MRI (4.55° vs 4.17°, respectively; P = .590). The percentage of patients in the bilateral group with a radiographic PTS >12° was 41.0% compared with 13.2% in the unilateral group (P = .012). The bilateral group had a significantly higher rate of an LPTS >7° compared with the unilateral group (53.8% vs 32.1%, respectively; P = .016) but not for an MPTS >7° (P = .190). On MRI, the LPTS (6.90°± 2.73°) was significantly greater than the MPTS (4.41°± 2.92°) (P < .001). There was a weak correlation between MPTS and radiographic PTS measurements (R = 0.24; P = .021), but LPTS and radiographic PTS measurements were not significantly correlated (R = 0.03; P = .810). Conclusion: Patients who underwent bilateral ACLR had a significantly greater PTS on radiography and a significantly greater LPTS on MRI compared with those who underwent unilateral ACLR. The rate of a radiographic PTS >12° was 2.4 times greater among patients undergoing bilateral ACLR compared with those undergoing unilateral ACLR. PTS measurements on radiography demonstrated a weak to negligible correlation with PTS measurements on MRI, suggesting that future normative PTS values should be reported specific to the imaging modality.

Poster 268: The Relation Between Posterior Tibial Slope Angle and Bilateral ACL Tear

Objectives: Increased posterior tibial slope (PTS) is a risk factor for primary anterior cruciate ligament (ACL) tear, as well as subsequent ACL graft tear. Prior literature has shown conflicting relationships between an increased PTS and bilateral ACL tears. The purpose of this study is to compare PTS angles for patients who had bilateral ACL tears to those who had only sustained a unilateral ACL tear. Methods: Retrospectively we identified patients who had bilateral and unilateral ACL tears at our institution over the last 10 years. Those who had bilateral surgery were matched to those who had unilateral surgery on a ratio of 1:1 based on age, sex, and BMI. Patients with unilateral ACL reconstruction were excluded if they had subsequent revisions or were less than 5 years post-operative. Lateral knee radiographs were used to measure the posterior tibial slope. The tibial axis was found using the circles measurement method which consisted of drawing circles along the tibial shaft and placing a line through the center of each to estimate the anatomical tibial axis. The PTS was then defined as the angle between the perpendicular line to this axis and the tibial plateau tangent line. Three blinded orthopedic residents performed these measurements. In addition to comparison of mean PTS between cohorts, both cohorts were stratified into “high slope” and “low slope” using 10-degress of PTS as a cutoff. An interclass correlation coefficient (ICC) was then calculated. Results: Fifty-three patients with bilateral ACL tears were successfully matched to 53 patients with unilateral tears. The average PTS in patients with bilateral ACL tears was found to be significantly higher than patients with unilateral ACL tears (11.17 vs. 9.72, p = 0.005). An intraclass correlation coefficient was calculated to 0.80 (95% confidence interval: 0.75 – 0.85). These cohorts were then stratified by the aforementioned sub-groups, finding that 69.8% of the bilateral cohort had more than 10-degrees of PTS, while this was true for only 46.4% of the unilateral cohort (p = 0.006). Conclusions: These results demonstrate that patients with bilateral ACL tears have higher PTS angles than those who only had unilateral ACL tear. Clinicians should consider routinely assessing PTS in a newly-presenting patient with an initial ACL tear, as marked deviations from the general population could be a predisposing risk factor for subsequent contralateral tear. Further prospective research is necessary to determine if patients with unilateral ACL tears who present with this radiographic finding are at greater risk for contralateral tear.

Paper 39: A Survival Analysis of ACL Graft and Contralateral ACL Ruptures in Patients Under 18 Years

Objectives: Although high rates of graft and contralateral anterior cruciate ligament (ACL) ruptures have been reported in younger patients after ACL reconstruction, recent evidence suggests that previously reported crude event rates underestimate the actual event risk. Therefore, the aim of this study was to report rates of graft and contralateral ACL rupture after ACL reconstruction in a large series of younger patients using survival analysis. Methods: A consecutive series of 400 patients who were under 18 years at the time of primary ACL reconstruction were identified from a single surgeon database over a 12-year period ending January 2018. Patients with a prior contralateral ACL rupture (n=8) or bilateral ACL ruptures (n=2) were excluded as were two patients who died within 6 months of surgery, leaving 388 (203M, 185F) in the final dataset. Bespoke survey data and clinic follow-up data were used to record graft rupture and contralateral ACL rupture events. Rates of graft and contralateral ACL rupture were calculated with Kaplan-Meier survival analysis. Log rank tests were used to compare survival functions between males and females. Results: The cumulative rates of graft rupture via survival analysis were 11% at 2 years, 16% at 4 years and 28% at 8 years. For contralateral ACL injury the cumulative rates were 7% at 2 years, 17% at 4 years and 49% at 8 years. Males had significantly greater rates of graft rupture than females although this was more prominent at 4 years (22% vs 9%) than at 8 years (31% vs 23%) after surgery (figure 1). Contralateral ACL rupture survival functions were not significantly different between male and female patients, although rates were higher in females until 5 years after which males had a notable increase in contralateral ACL ruptures with a cumulate rate of 63% at 8 years compared to 35% for females (figure2). Conclusions: The current study is one of the largest consecutive series of younger patients with one of the longest follow-up periods that reports a high risk for a second ACL injury. Over time, the cumulative risk for contralateral ACL rupture was higher than for graft rupture. This contradicts previous work that had shorter follow-up times. In males, the risk for contralateral ACL rupture substantially increased after 5 years. Understanding the postoperative time course for second ACL injury in young patients is important so that factors which contribute to this increased risk can be better understood and such injuries prevented.

Poster 325: Untreated Ruptures of the Anterior Cruciate Ligament: a 54 Year Follow-Up Study

Poster 325: Untreated Ruptures of the Anterior Cruciate Ligament: a 54 Year Follow-Up Study

A whole genome sequencing approach to anterior cruciate ligament rupture-a twin study in two unrelated families.

Predisposition to anterior cruciate ligament (ACL) rupture is multi-factorial, with variation in the genome considered a key intrinsic risk factor. Most implicated loci have been identified from candidate gene-based approach using case-control association settings. Here, we leverage a hypothesis-free whole genome sequencing in two two unrelated families (Family A and B) each with twins with a history of recurrent ACL ruptures acquired playing rugby as their primary sport, aimed to elucidate biologically relevant function-altering variants and genetic modifiers in ACL rupture. Family A monozygotic twin males (Twin 1 and Twin 2) both sustained two unilateral non-contact ACL ruptures of the right limb while playing club level touch rugby. Their male sibling sustained a bilateral non-contact ACL rupture while playing rugby union was also recruited. The father had sustained a unilateral non-contact ACL rupture on the right limb while playing professional amateur level football and mother who had participated in dancing for over 10 years at a social level, with no previous ligament or tendon injuries were both recruited. Family B monozygotic twin males (Twin 3 and Twin 4) were recruited with Twin 3 who had sustained a unilateral non-contact ACL rupture of the right limb and Twin 4 sustained three non-contact ACL ruptures (two in right limb and one in left limb), both while playing provincial level rugby union. Their female sibling participated in karate and swimming activities; and mother in hockey (4 years) horse riding (15 years) and swimming, had both reported no previous history of ligament or tendon injury. Variants with potential deleterious, loss-of-function and pathogenic effects were prioritised. Identity by descent, molecular dynamic simulation and functional partner analyses were conducted. We identified, in all nine affected individuals, including twin sets, non-synonymous SNPs in three genes: COL12A1 and CATSPER2, and KCNJ12 that are commonly enriched for deleterious, loss-of-function mutations, and their dysfunctions are known to be involved in the development of chronic pain, and represent key therapeutic targets. Notably, using Identity By Decent (IBD) analyses a long shared identical sequence interval which included the LINC01250 gene, around the telomeric region of chromosome 2p25.3, was common between affected twins in both families, and an affected brother’. Overall gene sets were enriched in pathways relevant to ACL pathophysiology, including complement/coagulation cascades (p = 3.0e-7), purine metabolism (p = 6.0e-7) and mismatch repair (p = 6.9e-5) pathways. Highlighted, is that this study fills an important gap in knowledge by using a WGS approach, focusing on potential deleterious variants in two unrelated families with a historical record of ACL rupture; and providing new insights into the pathophysiology of ACL, by identifying gene sets that contribute to variability in ACL risk.

Prophylactic administration of miR-451 inhibitor decreases osteoarthritis severity in rats

Transfection of chondrocytes with microRNA-451(miR-451), present in growth zone cartilage of the growth plate, upregulates production of enzymes association with extracellular matrix degradation. miR-451 is also present in articular cartilage and exacerbates IL-1β effects in articular chondrocytes. Moreover, when osteoarthritis (OA) was induced in Sprague Dawley rats via bilateral anterior cruciate ligament transection (ACLT), miR-451 expression was increased in OA cartilage compared to control, suggesting its inhibition might be used to prevent or treat OA. To examine the prophylactic and therapeutic potential of inhibiting miR-451, we evaluated treatment with miR-451 power inhibitor (451-PI) at the onset of joint trauma and treatment after OA had developed. The prophylactic animal cohort received twice-weekly intra-articular injections of either 451-PI or a negative control (NC-PI) beginning on post-surgical day 3. OA was allowed to develop for 24 days in the therapeutic cohort before beginning injections. All rats were killed on day 45. Micro-CT, histomorphometrics, OARSI scoring, and muscle force testing were performed on samples. 451-PI mitigated OA progression compared to NC-PI limbs in the prophylactic cohort based on histomorphometric analysis and OARSI scoring, but no differences were detected by micro-CT. 451-PI treatment beginning 24 days post-surgery was not able to reduce OA severity. Prophylactic administration of 451-PI mitigates OA progression in a post-trauma ACLT rat model supporting its potential to prevent OA development following an ACLT injury clinically.

Primary Repair versus Reconstruction in Patients with Bilateral Anterior Cruciate Ligament Injuries: What Do Patients Prefer?

Purpose The purpose is to evaluate knee preference and functional outcomes of patients with primary anterior cruciate ligament (ACL) repair in one knee and ACL reconstruction in the contralateral side. Methods All patients who underwent both procedures were retrospectively reviewed at minimum two-year follow-up. Patients were asked to complete questionnaires regarding their operated knees' preferences during rehabilitation, daily activities, sports activities, and overall function. Furthermore, the Subjective International Knee Documentation Committee, Forgotten Joint Score-12, and Anterior Cruciate Ligament-Return to Sport after Injury were completed. Results Twenty-one patients were included. All patients underwent ACL reconstruction first, which was displayed at younger age at surgery (24 vs. 33 years, p = 0.010) and longer follow-up (10.2 vs. 2.3 years, p < 0.001), respectively. Thirty-three percent preferred the repaired knee, 11% the reconstructed knee, and 56% had no preference; however, 78% indicated that their repaired knee was less painful during rehabilitation and 83% reported earlier range of motion (ROM) return following repair, which was similar for both knees in 17%. Eighty-three percent of patients indicated better function and progression during rehabilitation with their repaired knee and 11% with their reconstructed knees. No statistical differences were found in patient-reported outcomes between both procedures (all p > 0.4). Objective laxity assessment showed mean side-to-side difference of 0.6 mm between both sides in favor of the reconstructed knee. Conclusion This study showed that ACL repair and ACL reconstruction lead to similar functional outcomes. However, patients undergoing both procedures may have less pain, earlier ROM return, and faster rehabilitation progression following primary repair.

Comparison of Knee Function and Activity Level Between Bilateral and Unilateral ACL Reconstruction: A Matched-Group Analysis With Minimum 5-Year Follow-up.

Background:There is a lack of knowledge regarding knee function and activity level after bilateral anterior cruciate ligament reconstruction (ACLR) at midterm follow-up.Purpose:To compare activity level, patient-reported knee function, and quality of life in patients with bilateral ACLR and matched controls with unilateral ACLR at a minimum 5-year follow-up.Study Design:Cohort study; Level of evidence, 3.Methods:Patients with bilateral ACLR who were aged ≤40 years and had a second ACLR performed between 2010 and 2015 were identified in the authors’ local database. Surgical data and preoperative Knee injury and Osteoarthritis Outcome Score (KOOS) were extracted. The patients were sent a letter with questionnaires including the KOOS, EuroQol 5-Dimensions (EQ-5D), and EuroQol visual analog scale (EQ-VAS) and were asked study-specific questions by telephone regarding activity level and knee function at a minimum 5-year follow-up. For every patient with bilateral ACLR, a control matched for age ±2 years, sex, year ACLR was performed, and preinjury activity level or sport at the time of injury were identified in the database.Results:A total of 98 patients (mean age ± SD, 33.3 ± 7.3 years) with bilateral ACLR and 98 patients with unilateral ACLR (mean age ± SD, 33.1 ± 7.7 years) were included. The mean postoperative follow-up was 7.6 ± 1.8 years (from the second ACLR) for patients with bilateral ACLR and 7.8 ± 1.7 years for patients with unilateral ACLR. Patients with bilateral ACLR reported lower scores on all KOOS subscales, the EQ-5D, and the EQ-VAS at follow-up (P < .05). There was no difference in activity level between the groups at follow-up, but patients with bilateral ACLR were less satisfied with their activity level and knee function (P < .05).Conclusion:Patient-reported knee function and health-related quality of life were inferior in patients with bilateral ACLR compared with patients with unilateral ACLR. Patients with bilateral ACLR cannot expect the same knee function and quality of life as patients with unilateral ACLR.

Autologous Dedifferentiated Osteogenic Bone Marrow Mesenchymal Stem Cells Promote Bone Formation in a Rabbit Model of Anterior Cruciate Ligament Reconstruction versus Bone Marrow Mesenchymal Stem Cells

This study aimed to verify whether transplantation of dedifferentiated osteogenic bone marrow mesenchymal stem cells (De-BMSCs) at the tendon-bone interface could result in more bone formation than BMSC transplantation in anterior cruciate ligament (ACL) reconstruction. BMSCs from femur and tibia of New Zealand White rabbit were subjected to osteogenic induction and then cultured in osteogenic factor-free medium; the obtained cell population was termed De-BMSCs. Bilateral ACL reconstruction was performed in 48 adult rabbits. Three groups were established: control group with alginate gel injection, BMSCs group with the BMSCs injection, and De-BMSCs group with the De-BMSCs injection. At week 4 and 12 postoperatively, tendon-bone healing by histologic staining, micro-computed tomography examination, and biomechanical test were evaluated. The expression of α1 chain of type I collagen, osteocalcin, and osteopontin at the tendon-bone interface in the De-BMSCs group was greater than in the control or BMSCs group. The bone volume/total volume by micro-computed tomography scan was significantly greater in the De-BMSCs group than that in the control group (P= .013) or BMSCs group (P= .045) at 4 weeks, and greater than that in the control group (P= .014) or BMSCs group (P= .017) at 12 weeks. The tunnel area was significantly smaller in the De-BMSCs group than in the control group (P= .013) or BMSCs group (P= .044) at 12 weeks. The failure load and stiffness in De-BMSCs group were both significantly enhanced at 4 and 12 weeks than control group or De-BMSCs group. De-BMSCs transplantation can promote bone formation at the tendon-bone interface better than BMSCs transplantation in ACL reconstruction and increase the early biomechanical strength of the reconstructed ACL CLINICAL RELEVANCE: De-BMSCs transplantation is a potential choice for enhancing early bone formation in the tunnel in ACL reconstruction.

Pulsed electromagnetic field alleviates synovitis and inhibits the NLRP3/Caspase-1/GSDMD signaling pathway in osteoarthritis rats

ABSTRACT Low-grade inflammation is a key mediator of the pathogenesis of Osteoarthritis (OA). Pulsed electromagnetic field (PEMF) can improve the symptoms of OA and potentially acts as an anti-inflammatory. The aim of this study was to investigate the effect of the PEMF on OA and its relationship with the NLRP3/Caspase-1/GSDMD signaling pathway.18 Three-month-old Sprague-Dawley (SD) rats were randomly divided into three groups (n = 6 per group): 1) OA group, 2) OA+PEMF group (OA with PEMF exposure), 3) Control group (sham operation with placebo PEMF). Rats in the OA and OA+PEMF groups were subjected to bilateral anterior cruciate ligament transection and ovariectomy. PEMF scheme: Pulse waveform, 3.82 mT, 8 Hz, 40 min/day, 5 days a week, for 12 weeks. The expression levels of NLRP3, Caspase-1, GSDMD, IL-1β, and MMP-13 were detected by qRT-PCR and Western blot. The pathological structures of OA were monitored with Safranin O/fast green staining and hematoxylin eosin staining. Our results showed that PEMF alleviated the degree of inflammation and degeneration of cartilage in rats with OA, based on the histopathological changes and decline of the expression of IL-1β and MMP-13. Moreover, the over-expression of NLRP3, Caspase-1, and GSDMD in the cartilage of the OA rats decreased after PEMF treatment. These results suggested that PEMF could be a highly promising noninvasive strategy to slow down the progression of OA and inhibition of the NLRP3/Caspase-1/GSDMD signaling pathway might be involved in the beneficial effect of PEMF.

Graft Survivorship After Anterior Cruciate Ligament Reconstruction Based on Tibial Slope

Background: Increased tibial slope (TS) is believed to be a risk factor for anterior cruciate ligament (ACL) tears. Increased TS may also promote graft insufficiency after ACL reconstruction. Purpose: To delineate the relationship between TS and single as well as multiple graft insufficiencies after ACL reconstruction. Study Design: Cohort study; Level of evidence 3. Methods: We retrospectively identified 519 patients who had sustained ACL graft insufficiency after primary or revision ACL reconstruction (1 graft insufficiency, group A; 2 graft insufficiencies, group B; and ≥3 graft insufficiencies, group C). In addition, a subgroup analysis was conducted in 63 patients who received all surgical interventions by 2 specialized high-volume, single-center ACL surgeons. TS was measured by an observer with >10 years of training using lateral knee radiographs, and intrarater reliability was performed. Multiple logistic and univariate Cox regression was used to assess the contribution of covariates (TS, age, sex, and bilateral ACL injury) on repeated graft insufficiency and graft survival. Results: The study included 347 patients, 119 female and 228 male, who were 24 ± 9 years of age at their first surgery (group A, n = 260; group B, n = 62; group C, n = 25). Mean TS was 9.8°± 2.7° (range, 3°-18°). TS produced the highest adjusted odds ratio (1.73) of all covariates for repeated graft insufficiency. A significant correlation was found between TS and the number of graft insufficiencies (r = 0.48; P < .0001). TS was significantly lower in group A (9.0°± 2.3°) compared with group B (12.1°± 2.5°; P < .0001) and group C (12.0°± 2.6°; P < .0001). A significant correlation was seen between the TS and age at index ACL tear (r = −0.12; P = .02) as well as time to graft insufficiency (r = −0.12; P = .02). A TS ≥12° had an odds ratio of 11.6 for repeated ACL graft insufficiency. Conclusion: The current results indicate that patients with a markedly increased TS were at risk of early and repeated graft insufficiency after ACL reconstruction. Because the TS is rarely accounted for in primary and revision ACLR, isolated soft tissue procedures only incompletely address recurrent graft insufficiency in this subset of patients.

The ACL can hypertrophy in response to mechanical loading: an MRI study in elite athletes (157)

The ACL can hypertrophy in response to mechanical loading: an MRI study in elite athletes (157)

Symmetry and sex differences in knee kinematics and ACL elongation in healthy collegiate athletes during high‐impact activities revealed through dynamic biplane radiography

The objectives of this study were to determine symmetry and sex differences in knee kinematics and anterior cruciate ligament (ACL) elongation waveforms in healthy athletes without a history of a knee injury during fast running, drop jump, and 180° internal/external rotation hops. It was hypothesized that knee abduction angle and ACL relative elongation would be greater in women than in men during all activities. Bilateral knee kinematics and ACL relative elongation were determined in 19 collegiate athletes using dynamic biplane radiography. Sex differences in kinematics and ACL relative elongation waveforms were identified using statistical parametric mapping. Average absolute side-to-side differences (SSDA ) in kinematics and ACL relative elongation waveforms were determined for each activity. Women had up to 2.3° (all p < 0.05) less knee adduction angle and had greater ACL relative elongation (max. 4.8%-9.2%; all p < 0.01) than men during all activities, in support of the hypotheses. SSDA in kinematics were 1.4 mm and 5.5° or less in all components of translation and rotation, respectively, while SSDA in ACL relative elongation was 3.6% or less across all activities. Greater ACL relative elongation across a variety of activities may make women more susceptible to ACL injury than men. This study provides valuable reference data for identifying abnormal asymmetry in knee kinematics and ACL elongation in athletes after the ACL injury. These novel results improve our understanding of ACL elongation during demanding athletic activities and may help guide the development of sex-specific risk screening metrics, return to play assessments, and rehabilitation protocols after the ACL injury.

Narrow Notch Width is a Risk Factor for Anterior Cruciate Ligament Injury in the Pediatric Population: A Multicenter Study

PurposeThe purposes of this study were to evaluate the notch width index (NWI) as a risk factor for anterior cruciate ligament (ACL) rupture in the pediatric and adolescent patient population via multicenter analysis and to detect any differences in the NWI among cohorts having sustained either a unilateral or bilateral ACL rupture.MethodsA consecutive series of patients ≤19 years old was enrolled from January 1999 through July 2010 at 2 academic pediatric orthopaedic tertiary-care hospitals. Demographic and anatomic morphology data were collected for 3 cohorts: unilateral ACL ruptures, bilateral ACL ruptures, and a control group. A single blinded reviewer determined notch width measurements via T2 coronal magnetic resonance imaging sequences in a standardized manner, using a previously described technique.ResultsOf the 68 patients included for analysis, 22 sustained unilateral ACL rupture, 23 sustained bilateral ruptures, and 23 comprised the control group. There was a statistically significant difference appreciated in direct comparison of the NWI in the bilateral rupture group and the control group, as well as between the unilateral rupture group and the control group. There was no statistically significant difference between the NWI in the unilateral versus the bilateral rupture group.ConclusionGiven the known inconsistencies in the existing literature, our findings provide further support of a narrow NWI as a significant contributing factor to both unilateral and bilateral ACL injury risk in the pediatric and adolescent patient population.Level of EvidenceIII, retrospective cohort study.