Bone Bruise Distribution Patterns After Acute Anterior Cruciate Ligament Ruptures: Implications for the Injury Mechanism

High Detection Rate of Posterolateral Tibial Plateau Fractures and Poor Functional Outcomes in Type IIIB Impaction Fractures After Anterior Cruciate Ligament Rupture and Reconstruction

OBJECTIVE

The incidence of anterior cruciate ligament (ACL) ruptures has been increasing annually. However, clinical surgeons have overlooked the impaction fractures of the posterolateral tibial plateau and lateral femoral condyle in patients with ACL ruptures. The purpose of the present study was to report the detection rate of the posterolateral tibial plateau impaction fractures in patients with ACL ruptures, and to evaluate the functional outcomes of patients following ACL reconstruction (ACLR) without treatment of the tibial fractures at a 2-year postoperative follow-up.

METHODS

Four hundred eighty-eight patients treated for ACL ruptures between January 2016 and June 2020 were retrospectively reviewed, and the posterolateral tibial plateau impaction fractures were classified based on MRI assessment. The detection rate of the posterolateral tibial plateau impaction fractures was calculated, and the functional outcomes (SF-12 Mental Component Summaries, SF-12 Physical Component Summaries, Tegner, Lysholm, IKDC, and KOOS) were evaluated at a 2-year postoperative follow-up.

RESULTS

The detection rate of posterolateral tibial plateau impaction fractures was 41.6% among ACL ruptures. Of these, 285 cases (58.4%) had no fractures, 98 cases (20.1%) had type I impaction fractures, 41 cases (8.4%) had type IIA impaction fractures, 15 cases (3.1%) had type IIB impaction fractures, 22 cases (4.5%) had type IIIA impaction fractures, and 27 cases (5.5%) had type IIIB impaction fractures. Patients with type IIIA or IIIB impaction fractures showed an increased detection rate of contact mechanism compared to the other subgroups. Significant differences in Tegner (postoperation) and KOOS (QOL) were found between no fracture and type IIIB impaction fractures in patients following ACLR.

CONCLUSIONS

The detection rate of posterolateral tibial plateau impaction fractures in patients with ACL ruptures was high. Patients with type IIIB impaction fractures following ACLR had poor functional outcomes.

Biomechanical Determinants of Anterior Cruciate Ligament Stress in Individuals Post-ACL Reconstruction During Side-Cutting Movements

This cross-sectional laboratory-based study investigates the stress characteristics of the anterior cruciate ligament (ACL) during side-cutting using a knee finite element (FE) model and identifies biomechanical factors influencing ACL stress. Kinematics and ground reaction forces (GRF) were collected from eight participants (age: 30.3 ± 5.3 years; BMI: 25.6 ± 2.4 kg/m2; time since surgery: 12.8 ± 1.2 months) one year post-ACL reconstruction during side-cutting tasks. A knee FE model incorporating time-varying knee angles, knee forces, and femoral translation was developed to simulate the knee biomechanics. The relationships between ACL stress and lower limb biomechanics were analyzed. The results indicated the highest stress concentrations at the femoral attachment during the early landing phase. Posterior femoral displacement relative to the tibia was significantly correlated with peak ACL equivalent stress (r = 0.89, p = 0.003) and peak ACL shear stress (r = 0.82, p = 0.023). Peak ACL equivalent stress also showed positive correlations with posterior GRF (r = 0.77, p = 0.025) and knee extension moments (r = 0.71, p = 0.049). In contrast, peak ACL shear stress exhibited a significant negative correlation with hip extension moment (r = -0.80, p = 0.032). This study identified key biomechanical factors affecting ACL stress, highlighting the roles of femoral displacement, knee extension moments, and ground reaction forces, while demonstrating a negative relationship with hip extension moments.

Characterization of bone marrow edema patterns among patients with Segond fracture in the setting of acute anterior cruciate ligament injury: A comparative MRI study

PURPOSE

The purpose of this study is to investigate the anatomic distribution of bone marrow edema on MRI among patients who sustained a Segond fracture compared to those with an isolated ACL tear.

METHODS

A retrospective cohort study was performed of patients aged 18-40 years old who presented with an acute isolated ACL tear between January 2012 and May 2022. Two blinded readers reviewed all knee MRIs to assess bone marrow edema using the Whole-Organ Magnetic Resonance Imaging Score and the area of each sub-compartment was scored.

RESULTS

There were 522 patients in the final analysis, of which 28 patients (5.4%) were identified to have a Segond fracture. The Segond group demonstrated significantly greater rates of WORMS grades 2 and 3 in the central lateral femoral condyle, as well as the anterior, central, and posterior lateral tibial plateau. Furthermore, the Segond group demonstrated significantly greater rates of WORMS grades 2 and 3 in the central medial femoral condyle and the anterior medial tibial plateau. Bone edema at the central lateral femoral condyle (R = 0.034, p = 0.019) and central tibial plateau (R = 0.093, p = 0.033) were significantly correlated with lateral meniscus tears, while the edema in the posterior medial femoral condyle was correlated with medial meniscus tears (R = 0.127, p = 0.004).

CONCLUSION

Patients who present with ACL tear and a concomitant Segond fracture demonstrate significantly more extensive bone marrow edema in both the medial and lateral compartments of the knee compared to patients with an isolated ACL tear.

Effect of the Material Properties and Knee Position to the Bone Bruise Pattern in Skeletally Mature and Immature Subjects

A bone bruise is generated by a bony collision that could occur when the anterior cruciate ligament (ACL) is injured, and its pattern reflects the injury mechanism and skeletal maturity. Thus, the bone bruise pattern is useful to predict a subject-specific injury mechanism, although the sensitivity and/or effect of the material property and the knee position at injury is still unclear. The objective of the present study was to determine the effect of the material property and knee position on the bone bruise pattern in skeletally mature and immature subjects using finite element analysis. Finite element models were created from a magnetic resonance (MR) image in the sagittal plane of a skeletally mature (25 y. o.) and immature (9 y. o.) male subject. The femur and tibia were collided at 2 m/s to simulate the impact trauma and determine the maximum principal stress. The analysis was performed at 15, 30, and 45 deg of knee flexion, and neutral, 10 mm anterior and posterior translated position at each knee flexion angle. Although high stress was distributed toward the metaphysis area in the mature model, the stress did not cross the growth plate in the immature model. The size of the stress area was larger in the mature model than those in the immature model. The location of the stress area changed depending on the joint position. Young's modulus of cartilage and trabecular bone also affected the location of the stress area. The Young's modulus for the cartilage affected peak stress during impact, while the size of the stress area had almost no change. These results indicate that the bone bruise pattern is strongly associated with subject-specific parameters. In addition, the bone bruise pattern was affected not only by knee position but also by tissue qualities. In conclusion, although the bone bruise distribution was generally called footprint of the injury, the combined evaluation of the quality of the structure and the bone bruise distribution is necessary for properly diagnosing tissue injury based on the MR imaging.

Investigating the Bone Bruise Patterns in Pediatric Patients With Contact and Noncontact Acute Anterior Cruciate Ligament Tears: A Multicenter Study

BACKGROUND

In adults with anterior cruciate ligament (ACL) tears, bone bruises on magnetic resonance imaging (MRI) scans provide insight into the underlying mechanism of injury. There is a paucity of literature that has investigated these relationships in children with ACL tears.

PURPOSE

To examine and compare the number and location of bone bruises between contact and noncontact ACL tears in pediatric patients.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Boys ≤14 years and girls ≤12 years of age who underwent primary ACL reconstruction surgery between 2018 and 2022 were identified at 3 separate institutions. Eligibility criteria required detailed documentation of the mechanism of injury and MRI performed within 30 days of the initial ACL tear. Patients with congenital lower extremity abnormalities, concomitant fractures, injuries to the posterolateral corner and/or posterior cruciate ligament, previous ipsilateral knee injuries or surgeries, or closed physes evident on MRI scans were excluded. Patients were stratified into 2 groups based on a contact or noncontact mechanism of injury. Preoperative MRI scans were retrospectively reviewed for the presence of bone bruises in the coronal and sagittal planes using fat-suppressed T2-weighted images and a grid-based mapping technique of the tibiofemoral joint.

RESULTS

A total of 109 patients were included, with 76 (69.7%) patients sustaining noncontact injuries and 33 (30.3%) patients sustaining contact injuries. There were no significant differences between the contact and noncontact groups in terms of age (11.8 ± 2.0 vs 12.4 ± 1.3 years; P = .12), male sex (90.9% vs 88.2%; P > .99), time from initial injury to MRI (10.3 ± 8.1 vs 10.4 ± 8.9 days; P = .84), the presence of a concomitant medial meniscus tear (18.2% vs 14.5%; P = .62) or lateral meniscus tear (69.7% vs 52.6%; P = .097), and sport-related injuries (82.9% vs 81.8%; P = .89). No significant differences were observed in the frequency of combined lateral tibiofemoral (lateral femoral condyle + lateral tibial plateau) bone bruises (87.9% contact vs 78.9% noncontact; P = .41) or combined medial tibiofemoral (medial femoral condyle [MFC] + medial tibial plateau) bone bruises (54.5% contact vs 35.5% noncontact; P = .064). Patients with contact ACL tears were significantly more likely to have centrally located MFC bruising (odds ratio, 4.3; 95% CI, 1.6-11; P = .0038) and less likely to have bruising on the anterior aspect of the lateral tibial plateau (odds ratio, 0.27; 95% CI, 0.097-0.76; P = .013).

CONCLUSION

Children with contact ACL tears were 4 times more likely to present with centrally located MFC bone bruises on preoperative MRI scans compared with children who sustained noncontact ACL tears. Future studies should investigate the relationship between these bone bruise patterns and the potential risk of articular cartilage damage in pediatric patients with contact ACL tears.

Bone bruise distribution predicts anterior cruciate ligament tear location in non-contact injuries

Purpose

It is unclear whether different injury mechanisms lead to divergent anterior cruciate ligament (ACL) tear locations. This study aims to analyse the relationship between bone bruise (BB) distribution or depth and ACL tear location.

Methods

A retrospective analysis of 446 consecutive patients with acute non-contact ACL injury was performed. Only patients with complete ACL tears verified during subsequent arthroscopy were included. Magnetic resonance imaging (MRI) was used to classify BB location, BB depth, ACL tear location and concomitant injuries (medial/lateral meniscus and medial/lateral collateral ligament). Demographic characteristics included age, gender, body mass index (BMI), type of sport and time between injury and MRI. Multiple linear regression analysis was used to identify independent predictors of ACL tear location.

Results

One hundred and fifty-eight skeletally mature patients met the inclusion criteria. The presence of BB in the lateral tibial plateau was associated with a more distal ACL tear location (β = -0.27, p < 0.001). Less BB depth in the lateral femoral condyle showed a tendency towards more proximal ACL tears (β = -0.14; p = 0.054). Older age predicted a more proximal ACL tear location (β = 0.31, p < 0.001). No significant relationship was found between ACL tear location and gender, BMI, type of sport, concomitant injuries and time between injury and MRI.

Conclusion

ACL tear location after an acute non-contact injury is associated with distinct patterns of BB distribution, particularly involving the lateral compartment, indicating that different injury mechanisms may lead to different ACL tear locations.

Level of Evidence

Level III.

A Systematic Review of Bone Bruise Patterns following Acute Anterior Cruciate Ligament Tears: Insights into the Mechanism of Injury

(1) Background: The purpose of this systematic review was to determine the prevalence of bone bruises in patients with anterior cruciate ligament (ACL) injuries and the location of the bruises relative to the tibia and femur. Understanding the relative positions of these bone bruises could enhance our comprehension of the knee loading patterns that occur during an ACL injury. (2) Methods: The MEDLINE, EMBASE, and the Cochrane Library databases were searched for studies that evaluated the presence of bone bruises following ACL injuries. Study selection, data extraction, and a systematic review were performed. (3) Results: Bone bruises were observed in 3207 cases (82.8%) at the lateral tibia plateau (LTP), 1608 cases (41.5%) at the medial tibia plateau (MTP), 2765 cases (71.4%) at the lateral femoral condyle (LFC), and 1257 cases (32.4%) at the medial femoral condyle (MFC). Of the 30 studies, 11 were able to assess the anterior to posterior direction. The posterior LTP and center LFC were the most common areas of bone bruises. Among the 30 studies, 14 documented bone bruises across all four sites (LTP, MTP, LFC, and MFC). The most common pattern was bone bruises appearing at the LTP and LFC. (4) Conclusions: The most frequently observed pattern of bone bruises was restricted to the lateral aspects of both the tibia and femur. In cases where bone bruises were present on both the lateral and medial sides, those on the lateral side exhibited greater severity. The positioning of bone bruises along the front-back axis indicated a forward shift of the tibia in relation to the femur during ACL injuries.

Comparison of Bone Bruise Pattern Epidemiology between Anterior Cruciate Ligament Rupture and Patellar Dislocation Patients-Implications of Injury Mechanism

Different bone bruise patterns observed using magnetic resonance imaging (MRI) after non-contact anterior cruciate ligament (ACL) rupture and lateral patellar dislocation may indicate different knee injury mechanisms. In this study, 77 ACL ruptures and 77 patellar dislocations in knee MR images taken from patients with bone bruises at our institution between August 2020 and March 2022 were selected and analyzed. In order to determine typical bone bruising patterns following by ACL rupture and patellar dislocation, sagittal- and transverse-plane images were used to determine bone bruise locations in the directions of medial-lateral and superior-inferior with MR images. The presence, intensity, and location of the bone bruises in specific areas of the femur and tibial after ACL rupture and patellar dislocation were recorded. Relative bone bruise patterns after ACL rupture and patellar dislocation were classified. The results showed that there were four kinds of bone bruise patterns (1-, 2-, 3-, and 4- bone bruises) after ACL rupture. The most common two patterns after ACL rupture were 3- bone bruises (including the lateral femoral condyle and both the lateral-medial tibial plateau, LF + BT; both the lateral-medial femoral condyle and the lateral tibial plateau, BF + LT; and the medial femoral condyle and both the medial and lateral tibial plateau, MF + BT) followed by 4- bone bruises (both the lateral-medial femoral condyle and the tibial plateau, BF + BT), 2- bone bruises (the lateral femoral condyle and tibial plateau, LF + LT; the medial femoral condyle and the lateral tibial plateau, MF + LT; the lateral femoral condyle and the medial tibial plateau, LF + MT; the medial femoral condyle and the tibial plateau, MF + MT; both the lateral-medial tibial plateau, 0 + BT), and 1- bone bruise (only the lateral tibial plateau, 0 + LT). There was only a 1- bone bruise (the latera femoral condyle and medial patella bone bruise) for patellar dislocation, and the most common pattern of patellar dislocation was in the inferior medial patella and the lateral anterior inferior femur. The results suggested that bone bruise patterns after ACL rupture and patellar dislocation are completely different. There were four kinds of bone bruise patterns after non-contact ACL rupture, while there was only one kind of bone bruise pattern after patellar dislocation in patients, which was in the inferior medial patella and lateral anterior inferior femur.

The influence of distribution, severity and volume of posttraumatic bone bruise on functional outcome after ACL reconstruction for isolated ACL injuries

INTRODUCTION

Posttraumatic MRI of ACL tears show a high prevalence of bone bruise (BB) without macroscopic proof of chondral damage. Controversial results are described concerning the association between BB and outcome after ACL tear. Aim of this study is to evaluate the influence of distribution, severity and volume of BB in isolated ACL injuries on function, quality of life and muscle strength following ACL reconstruction (ACLR).

MATERIALS AND METHODS

MRI of n = 122 patients treated by ACLR without concomitant pathologies were evaluated. BB was differentiated by four localizations: medial/lateral femoral condyle (MFC/LFC) and medial/lateral tibial plateau (MTP/LTP). Severity was graded according to Costa-Paz. BB volumes of n = 46 patients were quantified (software-assisted volumetry). Outcome was measured by Lysholm Score (LS), Tegner Activity Scale (TAS), IKDC, isokinetics and SF-36. Measurements were conducted preoperatively (t0), 6 weeks (t1), 26 weeks (t2) and 52 weeks (t3) after ACLR.

RESULTS

The prevalence of BB was 91.8%. LTP was present in 91.8%, LFC 64.8%, MTP 49.2% and MFC 28.7%. 18.9% were classified Costa-Paz I, 58.2% II and 14.8% III. Total BB volume was 21.84 ± 15.27 cm3, the highest value for LTP (14.31 ± 9.93 cm3). LS/TAS/IKDC/SF-36/isokinetics improved significantly between t0-t3 (p < 0.001). Distribution, severity and volume had no influence on LS/TAS/IKDC/SF-36/isokinetics (n.s.).

CONCLUSIONS

No impact of BB after ACLR on function, quality of life and objective muscle strength was shown, unaffected by concomitant pathologies. Previous data regarding prevalence and distribution is confirmed. These results help surgeons counselling patients regarding the interpretation of extensive BB findings. Long-time follow-up studies are mandatory to evaluate an impact of BB on knee function due to secondary arthritis.

Semimembranosus Tendon Findings in Acute Anterior Cruciate Ligament Tears: MRI Evaluation and Associated Lesions

BACKGROUND

The semimembranosus (SM) tendon acts as a secondary dynamic stabilizer of the knee. It restrains external rotation and anterior translation of the medial compartment. Its role in the mechanism of injury during anterior cruciate ligament (ACL) rupture is unknown.

HYPOTHESIS

The bone bruise (BB) often detected at the posteromedial tibia in association with acute ACL tear may be related to the traction force from the SM tendon insertion. Magnetic resonance imaging (MRI) alterations can be detectable at the direct arm of the SM tendon in association with acute ACL injury.

STUDY DESIGN

Cross-sectional study: Level of evidence, 3.

METHODS

In the first study phase, 36 noninjured patients underwent knee MRI. The anatomic appearance of the SM tendon was evaluated. An imaging score for evaluating the SM tendon was developed for the purpose of the study. The intensity (in the axial or sagittal plane), morphology, and thickness of the distal SM tendon was evaluated and scored (4 total points). In the second study phase, 52 patients undergoing acute ACL reconstruction were included. Preoperative MRI was examined and scored, with documentation of BB at the posteromedial tibial plateau. Finally, arthroscopic diagnosis of a ramp lesion was confirmed. Logistic regression analysis was carried out for correlation between an altered MRI scoring system and the presence of BB at the posteromedial tibial plateau, the presence of a ramp lesion, or both.

RESULTS

Interrater agreement of 100% was obtained in the noninjured cohort (ie, no alteration found in any patient). The score validation in the cohort of patients with acute ACL injury showed a Cohen κ of 0.78 (interrater agreement, 82.7%). The direct arm of the SM tendon was altered in 35 of 52 patients (67.3%). A ramp lesion of the medial meniscus was arthroscopically detected in 21 patients (40.4%). The presence of BB at the posteromedial tibial plateau was detected in 33 patients (63.5%) and at the posterior medial femoral condyle in 1 (1.9%). Correlation analysis showed a significant association of a pathologic SM score with the presence of BB at the posteromedial tibial plateau (odds ratio = 2.7; P = .001). Conversely, no correlation was observed between the pathologic score and the presence of a ramp lesion (odds ratio = 0.88; P = .578).

CONCLUSION

The prevalence of pathologic findings in the direct arm of the SM tendon insertion was high in the acutely injured cohort with ACL rupture and is correlated with the presence of BB at the posteromedial tibial plateau. The main hypothesis formulated for the study was confirmed.

Relationship Between Bone Bruise Volume and Patient Outcomes After ACL Reconstruction

Background

Subchondral bone injuries, or bone bruises, are commonly observed on magnetic resonance imaging (MRI) after anterior cruciate ligament (ACL) injury. The current relationship between bone bruise volume and postsurgical outcomes remains poorly understood.

Purpose

To examine the influence of bone bruise volume on self-reported and objective functional outcomes at the time of return to play and 2 years following ACL reconstruction.

Study Design

Cohort study; Level of evidence, 3.

Methods

Clinical, surgical, and demographic data were obtained for a sample of convenience utilizing a single-surgeon ACL database (n = 1396). For 60 participants, femoral and tibial bone bruise volumes were estimated from preoperative MRI. Data obtained at the time of return to play included International Knee Documentation Committee (IKDC-2000) score, ACL-Return to Sport after Injury (ACL-RSI) score, and performance on an objective functional performance battery. Two-year follow-up data included graft reinjury rate, level of return to sport/activity, and self-reported knee function using the Single Assessment Numeric Evaluation (SANE). The forward stepwise linear regression was used to determine the relationship between bone bruise volume and patient function.

Results

The distribution of bone bruise injuries was as follows: lateral femoral condyle (76.7%), lateral tibial plateau (88.3%), medial femoral condyle (21.7%), and medial tibial plateau (26.7%). Mean total bone bruise volume of all compartments was 7065.7 ± 6226.6 mm³. At the 2-year follow up, there were no significant associations between total bone bruise volume and time of return to play (P = .832), IKDC-2000 score (P = .200), ACL-RSI score (P = .370), or SANE score (P = .179).

Conclusion

The lateral tibial plateau was the most frequent site to sustain bone bruise injury. Preoperative bone bruise volume was not associated with delayed time to return to sport or self-reported outcomes at time of return to play or at 2 years postoperatively.

Registration

NCT03704376 (ClinicalTrials.gov identifier).

Classification of Bone Bruises in Pediatric Patients With Anterior Cruciate Ligament Injuries

Background

Bone bruises are frequently found on magnetic resonance imaging (MRI) after an anterior cruciate ligament (ACL) tear in pediatric patients.

Purpose

To establish a classification system for different bone bruise patterns to estimate the severity of a knee injury in pediatric patients with ACL tears.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A medical database was retrospectively reviewed to identify all cases of primary ACL tears in patients who were aged ≤17 years at the time of the injury and underwent MRI at our institution within 4 weeks of the injury between January 2011 and December 2020. A total of 188 patients were identified (67 male, 121 female; mean age, 15.1 ± 1.4 years). Bone bruises were classified according to their depth and location on MRI in the sagittal and coronal planes.

Results

The new classification system identified 3 grades of depth: grade I, the bone bruise was located within the epiphysis but did not reach the epiphyseal plate (n = 54 [35.3%]); grade II, the bone bruise was within the epiphysis that reached the epiphyseal plate (n = 55 [35.9%]); and grade III, the bone bruise was in both the epiphysis and metaphysis (n = 44 [28.8%]). The bone bruise location was classified into 4 types: type a, the deepest bone bruise area was in the lateral tibial plateau (n = 66 [43.1%]); type b, the deepest bone bruise area was in the lateral femoral condyle, commonly occurring in the lateral one-third to two-thirds of the lateral femoral condyle (n = 22 [14.4%]); type c, the bone bruise area had a similar depth in both the lateral femoral condyle and lateral tibial plateau (n = 54 [35.3%]); and type d, the bone bruise area was in the lateral tibial plateau and lateral femoral condyle and extended to the fibular head (n = 11 [7.2%]). The prevalence of collateral ligament injuries increased from grade I to III. All patients with grade III type c bone bruises had meniscal lesions.

Conclusion

This new classification system provides a basis for estimating associated lesions of the knee before surgery.

The anterior cruciate ligament injury severity scale (ACLISS) is an effective tool to document and categorize the magnitude of associated tissue damage in knees after primary ACL injury and reconstruction

PURPOSE

To develop a tool allowing to classify the magnitude of structural tissue damage occurring in ACL injured knees. The proposed ACL Injury Severity Scale (ACLISS) would provide an easy description and categorization of the wide spectrum of injuries in patients undergoing primary ACL reconstruction, reaching from isolated ACL tears to ACL injuries with a complex association of combined structural damage.

METHODS

A stepwise approach was used to develop the ACLISS. The eligibility of each item was based on a literature search and a consensus between the authors after considering the diagnostic modalities and clinical importance of associated injuries to the menisci, subchondral bone, articular cartilage or collateral ligaments. Then, a retrospective analysis of associated injuries was performed in 100 patients who underwent a primary ACL reconstruction (ACLR) by a single surgeon. This was based on acute preoperative MRI (within 8 weeks after injury) as well as intraoperative arthroscopic findings. Depending on their prevalence, the number of selected items was reduced. Finally, an analysis of the overall scale distribution was performed to classify the patients according to different injury profiles.

RESULTS

A final scoring system of 12 points was developed (12 = highest severity). Six points were attributed to the medial and lateral tibiofemoral compartment respectively. The amount of associated injuries increased with ACLISS grading. The median scale value was 4.5 (lower quartile 3.0; higher quartile 7.0). Based on these quartiles, a score < 4 was considered to be an injury of mild severity (grade I), a score between ≥ 4 and ≤ 7 was defined as moderately severe (grade II) and a score > 7 displayed the most severe cases of ACL injuries (grade III). The knees were graded ACLISS I in 35%, ACLISS II in 49% and ACLISS III in 16% of patients. Overall, damage to the lateral tibiofemoral compartment was predominant (p < 0.01), but a proportional increase of tissue damage could be observed in the medial tibiofemoral compartment with the severity of ACLISS grading (p < 0.01).

CONCLUSIONS

The ACLISS allowed to easily and rapidly identify different injury severity profiles in patients who underwent primary ACLR. Injury severity was associated with an increased involvement of the medial tibiofemoral compartment. The ACLISS is convenient to use in daily clinical practice and represents a feasible grading and documentation tool for a reproducible comparison of clinical data in ACL injured patients.

LEVEL OF EVIDENCE

Level III.

The injury mechanism correlation between MRI and video-analysis in professional football players with an acute ACL knee injury reveals consistent bone bruise patterns

PURPOSE

To analyze the MRI features, in particular bone bruises pattern, of Anterior Cruciate Ligament (ACL) injured footballers, and to correlate them with the characteristics of injury mechanism and situation obtained from direct video footage.

METHODS

Nineteen professional football (soccer) players that sustained ACL injury while playing during an official match of First League Championship were included in the study. The video of injury was obtained from the Television broadcast. Knee Magnetic Resonance (MRI) was obtained within 7 days from the injury. BB and meniscal lesions were analyzed on MRI, while a video-analysis of mechanisms of ACL injury and injury dynamic were assessed from the videos.

RESULTS

The most commonly involved Bone Bruise areas in the knee were the Posterior Lateral Tibial Plateau (LTp) in 16 cases (84%) and the Central Lateral Femoral Condyle (LFc) in 11 cases (58%). Three patients (16%) had bone bruise in the Posterior Medial Tibial Plateau (MTp) while none (0%) had bone bruise in the Medial Femoral Condyle. Based on the bone bruise pattern, 11 (58%) had simultaneous LFc and LTp and were defined "Typical" while 8 (42%) had other locations or no bone bruise and were defined "Atypical". 9 out of 11 injuries (82%) of athletes with "Typical" pattern occurred with a "Pivoting" action", in contrast to only 1 case (12%) in those with "Atypical" bone bruise pattern (p = 0.0055). The most common situational mechanism pattern on video analysis was "pressing" (n = 7) accounting for the 47% of the "indirect" ACL injuries. In terms of movement pattern, ten injuries (52%) occurred during a "Pivoting" movement (7 pressing, 1 dribbling, 1 tackled, 1 goalkeeping), whereas the remaining were classified as "Planting" in four cases, "Direct Blow" in four cases and "Landing".

CONCLUSION

A well-defined and consistent bone bruise pattern involving the posterior tibial plateau and central femoral condyle of lateral compartment is present in footballers that sustained non-contact and indirect ACL injuries during pivoting with sudden change of direction/deceleration, while heterogeneous patterns were present in those with direct contact or injury mechanisms involving high horizontal velocity.

LEVEL OF EVIDENCE

Level IV.

Age and Bone Bruise Patterns Predict Tear Location in the Anterior Cruciate Ligament

Purpose

To assess the influence of demographic risk factors, anatomic risk factors, and injury mechanisms on anterior cruciate ligament (ACL) tear patterns.

Methods

All patients undergoing knee magnetic resonance imaging at our institution for acute ACL tears (within 1 month of injury) in 2019 were retrospectively analyzed. Patients with partial ACL tears and full-thickness posterior cruciate ligament injuries were excluded. On sagittal magnetic resonance images, the proximal and distal remnant lengths were measured, and the tear location was calculated as the distal remnant length divided by the total remnant length. Previously reported demographic and anatomic risk factors associated with ACL injury were then reviewed, including the notch width index, notch angle, intercondylar notch stenosis, alpha angle, posterior tibial slope, meniscal slope, and lateral femoral condyle index. In addition, the presence and severity of bone bruises were recorded. Finally, risk factors associated with ACL tear location were further analyzed using multivariate logistic regression.

Results

A total of 254 patients (44% male patients; mean age, 34 years; age range, 9-74 years) were included, of whom 60 (24%) had a proximal ACL tear (tear at the proximal quarter). Multivariate enter logistic regression analysis showed that older age (P = .008) was predictive of a more proximal tear location whereas open physes (P = .025), bone bruises in both compartments (P = .005), and posterolateral corner injury (P = .017) decreased the likelihood of a proximal tear (R ² = 0.121, P < .001).

Conclusions

No anatomic risk factors were identified to play a role in tear location. Although most patients have midsubstance tears, proximal ACL tears were more commonly found in older patients. Bone contusions involving the medial compartment are associated with midsubstance tears; these findings may indicate that different injury mechanisms play a role in the location at which the ACL tears.

Level of Evidence

Level III, prognostic, retrospective cohort study.

Bone Bruise Patterns in Ligamentous Injuries of the Knee With Focus on Anterior Cruciate Ligament

Introduction After sustaining an anterior cruciate ligament (ACL) injury, the bone bruises seen on magnetic resonance imaging (MRI) could reveal plenty of information regarding the loading mechanisms causing injury to the ACL. The current study was conducted to evaluate the common distribution patterns of bone bruises following an ACL injury and understand the loading mechanisms. Methods The knee MRI sequences of the patients operated arthroscopically for an injured ACL between August 2016 to August 2018 were selected for the study. The distribution pattern of the bone bruises was determined using the sagittal and coronal sections of MRI. The pattern of distribution of the bone bruises was categorized and analyzed by two independent observers.  Results Twenty-two patients were found to have bone bruises diagnosed in the MRI scans. The mean age of the patients was 27.8 ± 8.7 years. The pattern of a bone bruises in only the lateral femoral and tibial compartments was the most typical pattern observed in this study. The study pattern has a significant anterior distribution of bone bruises on the outer (lateral) compartment of both the femur and tibia as compared to the inner (medial) compartment (p< .05 and p > .05, respectively). The inter-rater reliability between the two observers by Cronbach's Alpha was 93.2%. Conclusion Having the appropriate information regarding the pattern distribution of bone bruises and the concomitant injuries associated with it furthers our knowledge and helps us understand the loading mechanisms of ACL tears. A combination of coup forces acting on the lateral compartment and the contrecoup varus force on the medial compartment of the knee during the primary pivot-shift injury suggests an an involvement of multiplanar loading patterns at the point of sustaining ACL tear.

A bone bruise at the lateral and medial tibial plateau with an anterior cruciate ligament injury is associated with a meniscus tear

PURPOSE

Bone bruises with anterior cruciate ligament (ACL) injury are well studied, but the association between bone bruises and multiple factors is unclear. The main objective of this study was to investigate the association between bone bruising and ACL injury and concomitant injury as well as clinical and functional scores. The second objective was to investigate the presence and distribution patterns of bone bruises.

METHOD

A total of 176 patients who underwent ACL reconstruction for primary ACL injury were included. The demographic characteristics and responses to clinical and functional assessments (the Visual Analog Scale for activities of daily living and sports, the Cincinnati Knee Rating System, the Lysholm score, the Knee Osteoarthritis Outcome Score and side-to-side difference in anterior laxity) were recorded at the initial visit. Concomitant injuries were evaluated by intraoperative assessment.

RESULTS

Bone bruises were detected in 141 patients (80.1%). The lateral femoral condyle (LFC) was the most common site in 116 patients (65.9%), followed by the lateral tibial plateau (LTP) in 82 patients (46.6%), medial tibial plateau (MTP) in 47 patients (26.7%) and medial femoral condyle (MFC) in 29 patients (16.5%). Regarding the distribution patterns, bone bruising at only the LFC, which was the most common pattern, was detected in 38 patients (27.0%). Bone bruising at the LTP or MTP was significantly associated with lateral (LM) and medial meniscus (MM) tears (odds ratios 4.0, 3.0, 4.3 and 40.5, 95% confidence intervals 1.5-11.6, 1.2-15.1, 1.2-17.3 and 8.6-283.0, respectively). No marked differences in the functional or clinical scores were noted. The severity of bone bruising at the MTP was significantly associated with MM tears and that at the LTP was significantly associated with LM tears. (p < 0.01).

CONCLUSION

This study showed association between bone bruising at LTP and LM tears or at MTP and MM tears. Additionally, it provided detailed information on the presence and distribution patterns of bone bruises at each anatomic site. These findings are clinically relevant and will aid in preoperatively diagnosing meniscus tears in cases of ACL injury.

LEVEL OF EVIDENCE

Level III.

Examining the Bone Bruise Patterns in Multiligament Knee Injuries With Peroneal Nerve Injury

BACKGROUND

Tibiofemoral bone bruise patterns seen on magnetic resonance imaging (MRI) are associated with ligamentous injuries in the acutely injured knee. Bone bruise patterns in multiligament knee injuries (MLKIs) and particularly their association with common peroneal nerve (CPN) injuries are not well described.

PURPOSE

To analyze the tibiofemoral bone bruise patterns in MLKIs with and without peroneal nerve injury.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We retrospectively identified 123 patients treated for an acute MLKI at a level 1 trauma center between January 2001 and March 2021. Patients were grouped into injury subtypes using the Schenck classification. Within this cohort, patients with clinically documented complete (motor and sensory loss) and/or partial CPN palsies on physical examination were identified. Imaging criteria required an MRI scan on a 1.5 or 3 Tesla scanner within 30 days of the initial MLKI. Images were retrospectively interpreted for bone bruising patterns by 2 board-certified musculoskeletal radiologists. The location of the bone bruises was mapped on fat-suppressed T2-weighted coronal and sagittal images. Bruise patterns were compared among patients with and without CPN injury.

RESULTS

Of the 108 patients with a MLKI who met the a priori inclusion criteria, 26 (24.1%) were found to have a CPN injury (N = 20 complete; N = 6 partial) on physical examination. For CPN-injured patients, the most common mechanism of injury was high-energy trauma (N = 19 [73%]). The presence of a grade 3 posterolateral corner (PLC) injury (N = 25; odds ratio [OR], 23.81 [95% CI, 3.08-184.1]; P = .0024), anteromedial femoral condyle bone bruising (N = 24; OR, 21.9 [95% CI, 3.40-202.9]; P < .001), or a documented knee dislocation (N = 16; OR, 3.45 [95% CI, 1.38-8.62]; P = .007) was significantly associated with the presence of a CPN injury. Of the 26 patients with CPN injury, 24 (92.3%) had at least 1 anteromedial femoral condyle bone bruise. All 20 (100%) patients with complete CPN injury also had at least 1 anteromedial femoral condyle bone bruise on MRI. In our MLKI cohort, the presence of anteromedial femoral condyle bone bruising had a sensitivity of 92.3% and a specificity of 64.6% for the presence of CPN injury on physical examination.

CONCLUSION

In our MLKI cohort, the presence of a grade 3 PLC injury had the greatest association with CPN injury. Additionally, anteromedial femoral condyle bone bruising on MRI was a highly sensitive finding that was significantly correlated with CPN injury on physical examination. The high prevalence of grade 3 PLC injuries and anteromedial tibiofemoral bone bruising suggests that these MLKIs with CPN injuries most commonly occurred from a hyperextension-varus mechanism caused by a high-energy blow to the anteromedial knee.

A Novel MRI Mapping Technique for Evaluating Bone Bruising Patterns Associated With Noncontact ACL Ruptures

Background:

Bone bruise patterns in the knee can aid in understanding the mechanism of injury in anterior cruciate ligament (ACL) ruptures. There is no universally accepted magnetic resonance imaging (MRI) mapping technique to describe the specific locations of bone bruises.

Hypothesis:

The authors hypothesized that (1) our novel mapping technique would show high interrater and intrarater reliability for the location of bone bruises in noncontact ACL-injured knees and (2) the bone bruise patterns reported from this technique would support the most common mechanisms of noncontact ACL injury, including valgus stress, anterior tibial translation, and internal tibial rotation.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Included were 43 patients who underwent ACL reconstruction between 2018 and 2020, with MRI within 30 days of the injury on a 3.0-T scanner, documentation of a noncontact mechanism of injury, and no concomitant or previous knee injuries. Images were retrospectively reviewed by 2 radiologists blinded to all clinical data. The locations of bone bruises were mapped on fat-suppressed T2-weighted coronal and sagittal images using a novel technique that combined the International Cartilage Repair Society (ICRS) tibiofemoral articular cartilage surgical lesions diagram and the Whole-Organ Magnetic Resonance Imaging Scoring (WORMS) mapping system. Reliability between the reviewers was assessed using the intraclass correlation coefficient (ICC), where ICC >0.90 indicated excellent agreement.

Results:

The interrater and intrarater ICCs were 0.918 and 0.974, respectively, for femoral edema mapping and 0.979 and 0.978, respectively, for tibial edema mapping. Significantly more bone bruises were seen within the lateral femoral condyle compared with the medial femoral condyle (67% vs 33%; P < .0001), and more bruises were seen within the lateral tibial plateau compared with the medial tibial plateau (65% vs 35%; P < .0001). Femoral bruises were almost exclusively located in the anterior/central regions (98%) of the condyles as opposed to the posterior region (2%; P < .0001). Tibial bruises were localized to the posterior region (78%) of both plateaus as opposed to the anterior/central regions (22%; P < .0001).

Conclusion:

The combined mapping technique offered a standardized and reliable method for reporting bone bruises in noncontact ACL injuries. The contusion patterns identified using this technique were indicative of the most commonly reported mechanisms for noncontact ACL injuries.

Return-to-sport quadriceps strength symmetry impacts 5-year cartilage integrity after anterior cruciate ligament reconstruction: A preliminary analysis

Quadriceps femoris strength asymmetry at the time of return to sports participation after anterior cruciate ligament (ACL) reconstruction contributes to worse function and asymmetric landing patterns, but the impact on longitudinal outcomes is not known. This study determined if young athletes after ACL reconstruction with quadriceps femoris strength asymmetry at a return to sports clearance would demonstrate markers of knee cartilage degeneration 5 years later compared to those with symmetric quadriceps femoris strength at return to sports. Participants (n = 27) were enrolled at the time of medical clearance for sports participation (baseline testing) and followed for 5 years. At baseline, quadriceps femoris strength was measured bilaterally and a limb symmetry index was used to divide the cohort into two groups: return to sport clearance with high quadriceps femoris strength (RTS-HQ; limb symmetry index ≥ 90%) and return to sport clearance with low quadriceps femoris strength (RTS-LQ; limb symmetry index < 85%). At 5 years post-baseline, quantitative magnetic resonance imaging (T2 relaxation times (ms): involved knee medial/lateral femoral condyle and tibial plateau) data were collected. Group differences were evaluated with independent samples t tests. At 5 years post-return to sports, the RTS-LQ strength group (n = 14) demonstrated elevated T2 relaxation times at the anterior region of the lateral femoral condyle compared to the RTS-HQ strength group (n = 13). Clinical Significance: Just over 50% of this cohort was cleared for sports participation with involved limb quadriceps femoris strength deficits that may contribute to early markers of knee cartilage degeneration within the subsequent 5 years.

Clinical Implications of Bone Bruise Patterns Accompanying Anterior Cruciate Ligament Tears

BACKGROUND

Anterior cruciate ligament (ACL) tears are common injuries; they are often associated with concomitant injuries to other structures in the knee, including bone bruises. While there is limited evidence that bone bruises are associated with slightly worse clinical outcomes, the implications of bone bruises for the articular cartilage and the risk of developing osteoarthritis (OA) in the knee are less clear. Recent studies suggest that the bone bruise pattern may be helpful in predicting the presence of meniscal ramp lesions.

EVIDENCE ACQUISITION

A literature review was performed in EMBASE using the keyword search phrase (acl OR (anterior AND cruciate AND ligament)) AND ((bone AND bruise) OR (bone AND contusion) OR (bone AND marrow AND edema) OR (bone AND marrow AND lesion) OR (subchondral AND edema)).

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

The literature search returned 93 articles of which 25 were ultimately included in this review. Most studies identified a high prevalence of bone bruises in the setting of acute ACL injury. Individual studies have found relationships between bone bruise volume and functional outcomes; however, these results were not supported by systematic review. Similarly, the literature has contradictory findings on the relationship between bone bruises and the progression of OA after ACL reconstruction. Investigations into concomitant injury found anterolateral ligament and meniscal ramp lesions to be associated with bone bruise presence on magnetic resonance imaging.

CONCLUSION

Despite the ample literature identifying the prevalence of bone bruises in association with ACL injury, there is little evidence to correlate bone bruises to functional outcomes or progression of OA. Bone bruises may best be used as a marker for concomitant injury such as medial meniscal ramp lesions that are not always well visualized on magnetic resonance imaging. Further research is required to establish the longitudinal effects of bone bruises on ACL tear recovery.

STRENGTH OF RECOMMENDATION TAXONOMY

2.

An Anterior Cruciate Ligament In Vitro Rupture Model Based on Clinical Imaging

BACKGROUND

Biomechanical studies on anterior cruciate ligament (ACL) injuries and reconstructions are based on ACL transection instead of realistic injury trauma.

PURPOSE

To replicate an ACL injury in vitro and compare the laxity that occurs with that after an isolated ACL transection injury before and after ACL reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

Nine paired knees were ACL injured or ACL transected. For ACL injury, knees were mounted in a rig that imposed tibial anterior translation at 1000 mm/min to rupture the ACL at 22.5° of flexion, 5° of internal rotation, and 710 N of joint compressive force, replicating data published on clinical bone bruise locations. In contralateral knees, the ACL was transected arthroscopically at midsubstance. Both groups had ACL reconstruction with bone-patellar tendon-bone graft. Native, ACL-deficient, and reconstructed knee laxities were measured in a kinematics rig from 0° to 100° of flexion with optical tracking: anterior tibial translation (ATT), internal rotation (IR), anterolateral (ATT + IR), and pivot shift (IR + valgus).

RESULTS

The ACL ruptured at 26 ± 5 mm of ATT and 1550 ± 620 N of force (mean ± SD) with an audible spring-back tibiofemoral impact with 5^o of valgus. ACL injury and transection increased ATT (P < .001). ACL injury caused greater ATT than ACL transection by 1.4 mm (range, 0.4-2.2 mm; P = .033). IR increased significantly in ACL-injured knees between 0° and 30° of flexion and in ACL transection knees from 0° to 20° of flexion. ATT during the ATT + IR maneuver was increased by ACL injury between 0° and 80° and after ACL transection between 0° and 60°. Residual laxity persisted after ACL reconstruction from 0° to 40° after ACL injury and from 0° to 20° in the ACL transection knees. ACL deficiency increased ATT and IR in the pivot-shift test (P < .001). The ATT in the pivot-shift increased significantly at 0° to 20° after ACL transection and 0° to 50° after ACL injury, and this persisted across 0° to 20° and 0° to 40° after ACL reconstruction.

CONCLUSION

This study developed an ACL injury model in vitro that replicated clinical ACL injury as evidenced by bone bruise patterns. ACL injury caused larger increases of laxity than ACL transection, likely because of damage to adjacent tissues; these differences often persisted after ACL reconstruction.

CLINICAL RELEVANCE

This in vitro model created more realistic ACL injuries than surgical transection, facilitating future evaluation of ACL reconstruction techniques.

Comparison Between Soccer and Basketball of Bone Bruise and Meniscal Injury Patterns in Anterior Cruciate Ligament Injuries

Background:

The varying effectiveness of anterior cruciate ligament (ACL) injury prevention programs between soccer and basketball may be due to differences in sport-specific injury mechanisms. Bone bruise patterns may provide information regarding injury mechanisms.

Purpose:

To compare bone bruise and meniscal injury patterns for ACL injuries sustained in soccer versus basketball.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Clinical notes, operative reports, and magnetic resonance imaging scans were reviewed for patients who sustained a noncontact ACL rupture while playing soccer or basketball between August 2016 and August 2018. The presence, location, and signal intensity of bone bruises on the tibia and femur were documented, and patterns were classified according to the location of the bone bruise in the lateral-medial direction. The meniscal and bone bruise injury patterns and the specific bone bruise locations were compared between the soccer and basketball groups.

Results:

Overall, 138 patients were included (56 with soccer-related and 82 with basketball-related ACL injury). No significant difference between the groups was observed in bone bruise patterns (P = .743) or meniscal injury patterns (P = .952). Bone bruise on the lateral side only of both the femur and the tibia was the most common pattern in both soccer (41.9%) and basketball (47.0%) groups; the most common meniscal injury type was an isolated lateral meniscal injury in both soccer (50.0%) and basketball (45.0%) groups. For patients with bone bruises on both the lateral and the medial sides of both the femur and the tibia (BF+BT), the bone bruise signal intensity on the lateral side of the femur (P < .001) and tibia (P = .009) was significantly higher than that on the medial side for both groups. The bone bruises on the lateral side of the femur (P < .001) and tibia (P = .002) were significantly more anterior than those on the medial side for patients with the BF+BT pattern.

Conclusion:

No significant differences in bone bruise location or meniscal injury type were detected when comparing ACL injuries sustained during soccer versus basketball. The study results suggest a similar biomechanical loading pattern for ACL injuries in these sports.

Response to the Letter to the Editor on "Prediction of Knee Kinematics at Time of Noncontact Anterior Cruciate Ligament Injuries Based on Bone Bruises"

The present Letter responded to the Letter to the Editor on "Prediction of Knee Kinematics at Time of Noncontact Anterior Cruciate Ligament Injuries Based on Bone Bruises" from Grassi et al.