Lateral femoral notch depth is not associated with increased rotatory instability in ACL-injured knees: a quantitative pivot shift analysis

Lateral femoral impaction fractures during an ACL tear extend posteriorly on the weight-bearing area of the tibiofemoral joint

PURPOSE

Posterior elongation of the physiological terminal sulcus (TS) due to lateral femoral condyle impaction fracture (LFC-IF) after an anterior cruciate ligament (ACL) tear could potentially decrease the weight-bearing area of the tibiofemoral joint, decrease the tension on lateral meniscus and cause flattening of the LFC which would influence rotational knee motion and cause anisometry of the lateral and anterolateral stabilizers. Therefore, the purpose of the study was to assess if the LFC-IF elongates the physiological TS posteriorly.

METHODS

One hundred patients magnetic resonance images (MRIs) (75 males, 25 females, mean age 32.2 years, SD = 8.2) were included with a 1:1 ratio between the full-thickness ACL tear group and the control group (patients with knee MRI performed due to other reasons, with no tear of ACL on MRI and negative clinical tests). Two independent raters evaluated the sagittal T1-weighted preselected MRI scans. The principal measurement of interest was the distance from the intersection of the Blumensaat line with subchondral bone to the posterior border of the TS/LFC-IF.

RESULTS

The median distance from the Blumensaat line to the posterior border of the TS/LFC-IF was significantly higher in the ACL tear group: 14.3 mm, interquartile range (IQR) = 11.6-16.4 mm versus control group: 12.8 mm, IQR = 9.0-15.0 mm, p = 0.038. Intrarater and inter-rater reliabilities were >0.90.

CONCLUSION

LFC-IF after full-thickness ACL tear significantly elongates the physiological TS in the posterior direction.

LEVEL OF EVIDENCE

Level III.

Editorial Commentary: Lateral Femoral Notch Sign Is a Marker of Past Pivot Trauma Rather Than a Predictor of Future Anterior Cruciate Ligament Failure

Predicting anterior cruciate ligament (ACL) reconstruction failure remains a challenge, shaped by anatomic, biomechanical, surgical, and rehabilitation factors. The lateral femoral notch sign (LFNS), present in 6% to 52% of ACL injuries, is linked to lateral meniscal tears (40%-67%), steeper posterior tibial slope (2.7° higher), and cartilage degradation. However, despite its correlation with injury severity, the LFNS has limited value in predicting ACL graft failure or postoperative instability. Recent studies reinforce that the LFNS is a marker of past pivot trauma, not a predictor of future ACL failure. While a deeper LFNS (>2 mm) correlates with more severe initial injury, it does not influence long-term graft survival or knee stability. Research shows that the LFNS resolves over time in pediatric patients, fails to correlate with residual tibial laxity or rotational instability, and is associated with nonprogressive chondral lesions. In contrast, modifiable factors-such as achieving optimal tunnel positioning and effectively managing rotational instability-play a far more decisive role in determining ACL reconstruction success than static imaging markers such as LFNS. Ultimately, the LFNS is a historical remnant, not a clinical decision-making tool in ACL failure risk assessment. It reminds us that successful outcomes hinge on a comprehensive approach rather than isolated imaging findings. Such imaging signs show scars of battles lost but often do not predict the outcome of the war.

Lateral Femoral Notch Sign Presence, Location, and Depth Are Not Associated With Primary Anterior Cruciate Ligament Reconstruction Failure: A Retrospective Case-Control Study

PURPOSE

To assess the relationship between the presence, depth, and location of the lateral femoral notch sign (LFNS) on preoperative magnetic resonance imaging (MRI) and the risk of anterior cruciate ligament reconstruction (ACLR) graft failure, as well as secondary return to sport (RTS) endpoints.

METHODS

Patients with primary ACLR failure between 2012 and 2021 were identified and matched to patients without primary ACLR failure by sex, age, and body mass index. Patients with incomplete medical records, inadequate follow-up, or concomitant lateral extra-articular tenodesis or anterolateral ligament reconstruction were excluded. The presence, depth, and location of the LFNS were recorded from patients' preoperative MRI. Intraoperative data, concomitant injuries, ACLR failure, and RTS were collected.

RESULTS

Of the 253 included patients, 158 (62.5%) were male, the mean age was 22 ± 9.1 years old, and the mean body mass index was 25.7 ± 5.7. 87(34.4%) had a LFNS on preoperative MRI. There was no difference in the prevalence of the LFNS between patients with primary ACLR failure (42 [32.1%]) and without primary ACLR failure (45 [36.9%]) (odds ratio 1.24, 95% confidence interval 0.74-2.08; P = .42). Among patients with the LFNS, there was no difference in mean depth between those with and without primary ACLR failure, or when stratifying depth by 1.0-1.5 mm, 1.5-2.0 mm, and >2.0 mm. The mean location of the LFNS from Blumensaat line did not differ between patients with or without primary ACLR failure, and RTS rate, level, and time were comparable between patients with and without the LFNS.

CONCLUSIONS

There was no significant difference in the presence, depth or location of the LFNS in patients with and without primary ACLR failure. Presence of the LFNS is not associated with additional risk of primary ACLR failure, and clinical outcomes were comparable in patients with and without the LFNS.

LEVEL OF EVIDENCE

Level IV, retrospective case-control study.

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.

Impaction Fractures of the Lateral Femoral Condyle Related to Anterior Cruciate Ligament Injury: A Scoping Review Concerning Diagnosis, Prevalence, Clinical Importance, and Management

Background

During pivot-shift anterior cruciate ligament (ACL) injury, bone bruises or impaction fractures of the lateral femoral condyle (LFC-IF) may occur due to impaction between the posterior part of the lateral tibial plateau and anterocentral part of the LFC. The purpose of the study was to systematically review the literature concerning the diagnosis, prevalence, clinical importance, and management of LFC-IF occurring during ACL injuries.

Methods

Included were studies concerning impaction fractures of the anterocentral part of the LFC occurring during ACL injuries. Studies concerning only bone bruises or cartilage lesions, without subchondral bone impaction, were not included. A search was performed in Medline and Scopus databases, with final search in May 2022. A secondary search was conducted within the bibliographies of included articles and using "Cited In" option. Two authors independently extracted data in three domains: study design, LFC-IF characteristics, and LFC-IF importance and management.

Results

A total of 35 studies were included for review with several studies reporting on multiple domains. Summarily, 31 studies were on the diagnosis and prevalence, 19 studies reported on the clinical importance, and 4 studies reported on the management of LFC-IF.

Conclusions

A LFC-IF occurs due to the pivot-shift mechanism of ACL injury. Its radiological feature is defined as an impaction of terminal sulcus deeper than 1 mm and is present in up to 52% of patients with a torn ACL. An LFC-IF causes injury to the cartilage, probably leads to its progressive degeneration, and is significantly associated with an increased risk of a lateral meniscus injury. A large LFC-IF might be associated with greater rotational knee instability. Although several techniques of LFC-IF treatment were proposed, none of them has been evaluated on a large cohort of patients to date.

Diagnostic value of the lateral femoral notch sign and kissing contusion in patients with anterior cruciate ligament injuries: a case-control study

INTRODUCTION

The lateral femoral notch sign (LFNS) and the kissing contusion (KC) are two indirect signs of anterior cruciate ligament (ACL) injuries. They can be used to diagnose ACL injuries.

MATERIALS AND METHODS

A total of 1000 patients were enrolled in this study, including 500 patients with ACL injuries who assigned to experimental group and 500 patients with meniscal tear (MT) who allocated to control group. All the patients underwent magnetic resonance imaging (MRI) preoperatively, and the diagnosis was confirmed with the aid of arthroscopy. The depth of LFNS and the presence of KC were determined on MRI findings. The relationship and characteristics between these two indicators was explored.

RESULTS

The notch depth of lateral femoral condyle in the experimental group (0.99 ± 0.56 mm) was significantly greater than that in the control group (0.49 ± 0.28 mm) (P < 0.05). The positive rate of KC in the experimental group (183/500) was markedly higher than that in the control group (3/500) (P < 0.05). The values of notch depth in patients who had ACL rupture concomitant lateral MT injuries and medial collateral ligament (MCL) injuries were 1.12 ± 0.64 and 1.23 ± 0.74 mm, respectively, which were significantly higher than those in patients with only ACL injury (0.89 ± 0.49 mm) (P < 0.05). It also was revealed that when the optimal cut-off point of LFNS was 0.72 mm (area under the curve (AUC) = 81%), the values of specificity and sensitivity were 67% and 84%, respectively. For KC, the corresponding values were 36.6% and 99.4%, respectively. The diagnostic outcome of LFNS was not in agreement with that of KC, as there was a poor coincidence according to the Kappa coefficient (Kappa = 0.155 < 0.4, P = 0.035).

CONCLUSION

The LFNS and KC have strong clinical significance in the diagnosis of ACL injuries. A deeper notch often indicates a more complex knee injury. Notch depth equal to 0.72 mm can be basically considered as the optimal cut-off point for LFNS in statistics.

Posterior tibial plateau impaction fractures are not associated with increased knee instability: a quantitative pivot shift analysis

PURPOSE

This study aimed to evaluate posterolateral tibial plateau impaction fractures and how they contribute to rotatory knee laxity using quantitative pivot shift analysis. It was hypothesised that neither the presence of nor the degree of involvement of the plateau would affect rotatory knee laxity in the ACL-deficient knee.

METHODS

A retrospective review of prospectively collected data on 284 patients with complete anterior cruciate ligament (ACL) injuries was conducted. Posterolateral tibial plateau impaction fractures were identified on preoperative MRI. The patients were divided into two cohorts: "fractures" or "no fractures". The cohort with fractures was further categorised based on fracture morphology: "extra-articular", "articular-impaction", or "displaced-articular fragment". All data were collected during examination under anaesthesia performed immediately prior to ACL reconstruction. This included a standard pivot shift test graded by the examiner and quantitative data including anterior tibial translation (mm) via Rolimeter, quantitative pivot shift (QPS) examination (mm) via PIVOT tablet technology, and acceleration (m/sec²) during the pivot shift test via accelerometer. Quantitative examinations were compared with the contralateral knee.

RESULTS

There were 112 patients with posterolateral tibial plateau impaction fractures (112/284, 39%). Of these, 71/112 (63%) were "extra-articular", 28/112 (25%) "articular-impaction", and 13/112 (12%) "displaced-articular". Regarding the two groups with or without fractures, there was no difference in subjective pivot shift (2 ± 0 vs 2 ± 0, respectively,  n.s.), QPS (2.4 ± 1.6 mm vs 2.7 ± 2.2 mm, respectively, n.s.), anterior tibial translation measurements (6 ± 3 mm vs 5 ± 3 mm, respectively, n.s.), or acceleration of the knee during the pivot (1.7 ± 2.3 m/s² vs 1.8 ± 3.1 m/s², respectively, n.s.). When the fractures were further subdivided, subgroup analysis revealed no significant differences noted in any of the measured examinations between the fracture subtypes.

CONCLUSION

This study showed that the posterolateral tibial plateau impaction fractures are commonly encountered in the setting of ACL tears; however, contrary to previous reports, they do not significantly increase rotatory knee laxity. This suggests that this type of concomitant injury may not need to be addressed at the time of ACL reconstruction.

LEVEL OF EVIDENCE

Level III.

The lateral femoral notch sign and coronal lateral collateral ligament sign in magnetic resonance imaging failed to predict dynamic anterior tibial laxity

Purpose

To investigate the relationship between the lateral femoral notch sign as well as the coronal lateral collateral ligament (LCL) sign and anterior tibial translation using the GNRB arthrometer in patients with anterior cruciate ligament (ACL) injuries.

Methods

Forty-six patients with ACL injuries were retrospectively included from May 2020 to February 2022; four patients were excluded due to incomplete data. Magnetic resonance imaging (MRI) were reviewed for the lateral femoral notch sign and the coronal LCL sign. The GNRB arthrometer was used to evaluate the dynamic anterior tibial translation of the knee, and the side-to-side differences (SSDs) in tibial translation between the injured knee and healthy knee were calculated at different force levels. Two types of slopes for displacement-force curves were acquired.

Results

Six patients (14.3%) had the positive lateral femoral notch sign (notch depth > 2.0 mm), and 14 patients (33.3%) had the positive coronal LCL sign. The SSD of the anterior tibial translations under different loads as well as the slopes of displacement-force curves were the same in the positive and negative notch sign groups (p all > 0.05) and between the positive and negative coronal LCL sign groups (p all > 0.05). Meanwhile, the measured notch depth and notch length were also not significantly correlated with the anterior tibial translation SSD in the GNRB.

Conclusion

The presence of the lateral femoral notch sign and the coronal LCL sign did not indicate greater dynamic tibial laxity as measured using the GNRB.

[Research progress of lateral femoral notch sign in diagnosis of anterior cruciate ligament rupture]

Objective

To summarize the relationship between lateral femoral notch sign (LFNS) and anterior cruciate ligament (ACL) rupture.

Methods

The relevant literature of LFNS at home and abroad in recent years was retrospectively reviewed, and its mechanism, diagnostic criteria and influencing factors in diagnosis of ACL rupture were summarized and analyzed.

Results

The LFNS is associated with rotational stability of the knee. As an indirect sign of ACL rupture, the LFNS has high clinical diagnostic value, especially the diagnosis of ACL rupture with lateral meniscus injury.

Conclusion

The diagnostic criteria and influencing factors of LFNS in diagnosis of ACL rupture are still unclear and controversial, which needs further study.

High prevalence of a deep lateral femoral notch sign in patients with anterior cruciate ligament (ACL) and concomitant posterior root tears of the lateral meniscus

PURPOSE

To determine the prevalence of a deep lateral femoral notch sign (LFNS) in magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) and concomitant posterior root tears of the lateral meniscus (PLRT).

METHODS

A retrospective chart review was conducted to identify all patients undergoing ACL reconstruction between 2016 and 2018. Based on the arthroscopic appearance of the lateral meniscus, patients were assorted to one of three groups: isolated ACL tear (ACL-Group), ACL tear with concomitant lateral meniscus tear not involving the posterolateral root (Meniscus-Group), and ACL tear with concomitant PLRT (PLRT-Group). Incidence and depth of a LFNS on preoperative MRI was compared between the three cohorts.

RESULTS

115 patients (mean age: 29.5 ± 11.3 years) were included in the study, with 58 patients (50.4%) assorted to the ACL-Group, 24 patients (20.9%) to the Meniscus-Group, and 33 patients (28.7%) to the PLRT-Group. The prevalence of a LFNS was significantly higher in the PLRT-Group (39.4%), when compared to the ACL- (5.2%) or Meniscus-Groups (25.0%; p < 0.001, respectively). Additionally, logistic regression analysis demonstrated that patients with PLRT were 5.3 times more likely to have a LFNS as compared to those without a lateral root tear (p < 0.001).

CONCLUSION

In patients with ACL tears, the presence of a LFNS on preoperative MRI may be predictive for a PLRT. As the LFNS occurs in almost 40% of the patients with combined ACL tears and PLRT, the LFNS may be a useful secondary diagnostic finding in early MRI diagnostic. Identifying PLRT on MRI is clinically relevant, as it prevents misdiagnosis and facilitates surgical decision-making, thus avoiding subsequent delayed treatment.

LEVEL OF EVIDENCE

Level IV.

Femoral and tibial bone bruise volume is not correlated with ALL injury or rotational instability in patients with ACL-deficient knee

PURPOSE

Some researchers have suggested that bone bruises are evidence of rotational instability. The hypothesis was that the extent of lateral bone edema is correlated with the presence of an anterolateral ligament (ALL) injury. The main objective was to determine whether there was a correlation between the presence of an ALL injury the extent of bone bruises.

METHODS

A prospective diagnostic study enrolled all the patients who suffered an acute anterior cruciate ligament (ACL) who were operated on within 8 weeks. The extent of bone bruising according to the ICRS classification was measured on preoperative MRIs by two independent blinded raters twice with an interval of 4 weeks. Dynamic ultrasonography (US) to look for ALL injury and the pivot shift test were performed before the ACL surgery. The correlation between ALL injury and bone bruises, and the correlation between an ALL injury and a high-grade pivot shift test were determined.

RESULTS

Sixty-one patients were included; 52% of patients had an ALL injury on US. The extent of lateral bone bruise was not related to the presence of an ALL injury, nor related to the presence of a high-grade pivot shift. A grade 2 or 3 pivot shift was significantly correlated with an ALL injury (p < 0.0001). Inter- and intra-rater reliability for the bone bruise rating was excellent.

CONCLUSION

The extent of lateral bone bruise is not correlated with ALL injury or a high-grade pivot shift; thus, it is not correlated with rotational instability of the knee.

LEVEL OF EVIDENCE

II.

The Lateral Femoral Notch Sign Is Correlated With Increased Rotatory Laxity After Anterior Cruciate Ligament Injury: Pivot Shift Quantification With A Surgical Navigation System

BACKGROUND

The lateral femoral notch sign (LNS) is a bony impression on the lateral femoral condyle correlated with anterior cruciate ligament (ACL) injury. Its presence is associated with lateral meniscal injury and higher cartilage degradation on the lateral femoral condyle.

PURPOSE/HYPOTHESIS

The purpose was to investigate the effect of the presence and magnitude of LNS on rotatory instability. The hypothesis was that a positive LNS is correlated with a high-grade pivot shift (PS).

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 90 consecutive patients with complete ACL tears between 2013 and 2017 underwent intraoperative kinematic evaluation with the surgical navigation system and were included in the present study. The same surgeon performed a standardized PS under anesthesia. The PS was quantified through the acceleration of the lateral compartment during tibial reduction (PS ACC) and the internal-external rotation (PS IE). Presence and depth of LNS were evaluated on sagittal magnetic resonance images (1.5-T).

RESULTS

In 47 patients, the LNS was absent; in 33, the LNS depth was between 1 mm and 2 mm; and in 10 patients, it was deeper than 2 mm. Patients with a notch deeper than 2 mm showed increased PS ACC and PS IE compared with the group without the LNS. However, no significant differences were present between the group with a notch between 1 and 2 mm and the patients without LNS. Receiver operating characteristic curve analysis showed that 2 mm was the most predictive cutoff value to identify the "high-grade rotatory instability" group, with an accuracy of 77.8% and 74.4% and a specificity of 95.5% and 93.9% referred to the PS ACC and PS IE, respectively.

CONCLUSION

The presence of a lateral LNS deeper than 2 mm could be used for the preoperative identification of patients with a high risk of increased rotatory instability.

Knee laxity, lateral meniscus tear and distal femur morphology influence pivot shift test grade in ACL injury patients

PURPOSE

Although several factors have been considered to be associated with pivot shift test grade in ACL injured patients, a conclusion regarding which factors contribute to the pivot shift test grade has not been reached. The purpose of this study was to identify factors associated with preoperative pivot shift test grade.

METHODS

Three hundred and sixty-six consecutive patients who underwent ACL reconstruction in our hospital were enrolled in the study. Patients were divided into two groups on the basis of preoperative pivot shift test grade (Mild: grade 0-3, Severe: grade 4-6). First, 13 independent variables (age, gender, period from injury to surgery, hyperextension, KT measurement, contralateral side pivot shift test grade, medial and lateral tibial slope, lateral condyle length, lateral condyle height, distal femoral condyle offset, medial and lateral meniscus tear) were analyzed by one-way ANOVA and Chi-squared test. Binary Logistic regression was then performed based on the results of univariate analyses (independent variables of p < 0.2 were included).

RESULTS

Hyperextension, lateral meniscus tear, contralateral side pivot shift test grade, distal femoral condyle offset and KT measurement were identified as risk factors for preoperative pivot shift grade via logistic regression analysis.

CONCLUSION

The current study revealed that hyperextension, lateral meniscus tear, contralateral side pivot shift test grade, distal femoral condyle offset and anterior instability were associated with preoperative pivot shift grade. Patients with above factors that cannot be modified during surgery may need special consideration when ACL reconstruction is performed, as greater preoperative pivot shift has been proven to be a risk factor for residual pivot shift after ACL reconstruction.

LEVEL OF EVIDENCE

III.

Objectifying the Pivot Shift Test

The pivot shift test is utilized for assessment of rotatory instability in the anterior cruciate ligament (ACL) deficient knee. There are multiple reports of the pivot shift maneuver, and there is a lack of consensus among clinicians as to a standardized maneuver. Measurement devices are a feasible option to evaluate rotatory knee instability, objectively or quantitatively. Traditionally, measurement systems have been invasive systems. More recently, electromagnetic system, inertial sensor, or imaging analysis systems, specifically with the utilization of a tablet computer, have emerged as noninvasive, and more importantly, validated options. It is important to recognize that anatomic structures other than the ACL contribute to rotatory knee stability. Addressing the tibial slope, anterolateral structures of the knee, specifically the iliotibial band, and menisci during ACL surgery may decrease residual pivot shift in an attempt to improve clinical outcomes and prevent reinjury. This review article describes the pivot shift maneuver, objective measurement tools, and clinical applications of the pivot shift test.

Patient-Reported and Quantitative Outcomes of Anatomic Anterior Cruciate Ligament Reconstruction With Hamstring Tendon Autografts

Background:

The pivot-shift test has become more consistent and reliable and is a meaningful outcome measurement after anterior cruciate ligament reconstruction (ACLR).

Purpose/Hypothesis:

The purpose of this investigation was to assess patient-reported outcomes (PROs) and the quantitative pivot shift (QPS) preoperatively, at time zero immediately after anatomic ACLR, and after 24 months as well as the relationship between PROs and the QPS. It was hypothesized that anatomic ACLR would restore rotatory stability measured by the pivot-shift test and that QPS measurements would be positively correlated with PROs.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

The ACL-injured and contralateral uninjured knees from 89 of 107 (83.2%) enrolled patients at 4 international centers were evaluated using a standardized pivot-shift test. Tibial acceleration was assessed with an inertial sensor, and lateral compartment translation was measured using an image analysis system preoperatively, at time zero immediately postoperatively, and at follow-up after 2 years. PROs were assessed at 12 and 24 months postoperatively with the International Knee Documentation Committee (IKDC) subjective knee form, Cincinnati Knee Rating System (CKRS), Marx activity rating scale, and activity of daily living score (ADLS).

Results:

The mean patient age at surgery was 27 years (range, 15-45 years). A positive pivot shift preoperatively (side-to-side difference in tibial acceleration, 2.6 ± 4.0 m/s²; side-to-side difference in anterior tibial translation, 2.0 ± 2.0 mm) was reduced at time zero postoperatively (side-to-side difference in tibial acceleration, –0.5 ± 1.3 m/s²; side-to-side difference in anterior tibial translation, –0.1 ± 1.0 mm). All PROs improved from preoperatively to final follow-up at 24 months: from 56.5 to 85.5 points for the IKDC (P = .0001), from 28.8 to 32.4 points for the CKRS (P = .04), from 11.2 to 7.9 points for the Marx (P < .0001), and from 75.7 to 91.6 points for the ADLS (P < .0001). Neither preoperative nor time zero postoperative rotatory laxity assessed by the pivot-shift test correlated with PROs at 24-month follow-up. A graft retear was observed in 4 patients (4.5%) within 2 years of follow-up.

Conclusion:

Anatomic ACLR resulted in significantly improved and acceptable PROs at 2-year follow-up and a low failure rate. Anatomic ACLR restored QPS measurements of anterior tibial translation and tibial acceleration to those of the contralateral knee immediately after surgery while still under anesthesia, but there was no correlation between the QPS preoperatively or at time zero after ACLR and PROs at 2-year follow-up.

Fate of the lateral femoral notch following early anterior cruciate ligament reconstruction

BACKGROUND

The goal of this longitudinal study was to investigate the fate of the lateral femoral notch (LFN), which is frequently seen as an impaction fracture of the lateral femoral condyle in patients with anterior cruciate ligament (ACL) tears.

METHODS

Patients who underwent early ACL reconstruction between 2006 and 2010 were reviewed. If post-injury magnetic resonance images showed an LFN greater than 1.5 mm in depth, patients with untreated LFN were followed. Two blinded observers performed quantitative and qualitative imaging analysis.

RESULTS

Sixteen patients (five women, 11 men) were available for follow-up nine years (six to 10 years) post-injury. The median defect area of the LFN significantly decreased from 2.3 cm² (range: 0.9-3.8 cm²) to 1.6 cm² (range: 0.4-3.2 cm²) (P < .001). The defect depth did not significantly change from 2.3 mm (range: 2.0-3.6 mm) to 2.5 mm (range: 1.3-3.6 mm) (P > .05). The International Cartilage Repair Society (ICRS) score increased from 1.5 (range: 0-3) post-injury to 2.0 (range: 0-4) at follow-up (P < .01). The Lysholm score was 93 (72-100), the Tegner activity level was 6 (3-9) and the knee injury and osteoarthritis outcome score (KOOS) score was 97 (91-100).

CONCLUSIONS

The defect area of the LFN decreased overtime, whereas the depth of the impression remained. Focal cartilage lesions were found in all except two patients post-injury and progressed during follow-up. However, patient-reported outcome scores were satisfying.

Rotatory Knee Laxity Exists on a Continuum in Anterior Cruciate Ligament Injury

BACKGROUND

The purpose of this investigation was to compare the magnitude of rotatory knee laxity in patients with a partial anterior cruciate ligament (ACL) tear, those with a complete ACL tear, and those who had undergone a failed ACL reconstruction. It was hypothesized that rotatory knee laxity would increase with increasing injury grade, with knees with partial ACL tears demonstrating the lowest rotatory laxity and knees that had undergone failed ACL reconstruction demonstrating the highest rotatory laxity.

METHODS

A prospective multicenter study cohort of 354 patients who had undergone ACL reconstruction between 2012 and 2018 was examined. All patients had both injured and contralateral healthy knees evaluated using standardized, preoperative quantitative pivot shift testing, determined by a validated, image-based tablet software application and a surface-mounted accelerometer. Quantitative pivot shift was compared with the contralateral healthy knee in 20 patients with partial ACL tears, 257 patients with complete ACL tears, and 27 patients who had undergone a failed ACL reconstruction. Comparisons were made using 1-way analysis of variance (ANOVA) with post hoc 2-sample t tests with Bonferroni correction. Significance was set at p < 0.05.

RESULTS

There were stepwise increases in side-to-side differences in quantitative pivot shift in terms of lateral knee compartment translation for patients with partial ACL tears (mean [and standard deviation], 1.4 ± 1.5 mm), those with complete ACL tears (2.5 ± 2.1 mm), and those who had undergone failed ACL reconstruction (3.3 ± 1.9 mm) (p = 0.01) and increases in terms of lateral compartment acceleration for patients with partial ACL tears (0.7 ± 1.4 m/s), those with complete ACL tears (2.3 ± 3.1 m/s), and those who had undergone failed ACL reconstruction (2.4 ± 5.5 m/s) (p = 0.01). A significant difference in lateral knee compartment translation was found when comparing patients with partial ACL tears and those with complete ACL tears (1.2 ± 2.1 mm [95% confidence interval (CI), 0.2 to 2.1 mm]; p = 0.02) and patients with partial ACL tears and those who had undergone failed ACL reconstruction (1.9 ± 1.7 mm [95% CI, 0.8 to 2.9 mm]; p = 0.001), but not when comparing patients with complete ACL tears and those who had undergone failed ACL reconstruction (0.8 ± 2.1 [95% CI, -0.1 to 1.6 mm]; p = 0.09). Increased lateral compartment acceleration was found when comparing patients with partial ACL tears and those with complete ACL tears (1.5 ± 3.0 m/s [95% CI, 0.8 to 2.3 m/s]; p = 0.0002), but not when comparing patients with complete ACL tears and those who had undergone failed ACL reconstruction (0.1 ± 3.4 m/s [95% CI, -2.2 to 2.4 m/s]; p = 0.93) or patients with partial ACL tears and those who had undergone failed ACL reconstruction (1.7 ± 4.2 m/s [95% CI, -0.7 to 4.0 m/s]; p = 0.16). An increasing lateral compartment translation of the contralateral, ACL-healthy knee was found in patients with partial ACL tears (0.8 mm), those with complete ACL tears (1.2 mm), and those who had undergone failed ACL reconstruction (1.7 mm) (p < 0.05).

CONCLUSIONS

A progressive increase in rotatory knee laxity, defined by side-to-side differences in quantitative pivot shift, was observed in patients with partial ACL tears, those with complete ACL tears, and those who had undergone failed ACL reconstruction. These results may be helpful when assessing outcomes and considering indications for the management of high-grade rotatory knee laxity.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Patients With Failed Anterior Cruciate Ligament Reconstruction Have an Increased Posterior Lateral Tibial Plateau Slope: A Case-Controlled Study

PURPOSE

To compare knee anatomical parameters of patients with failed anterior cruciate ligament reconstruction (ACL-R) with those of a control group of sex-matched patients with successful ACL-R.

METHODS

Forty-three patients (34 male, 9 female) who experienced graft failure after ACL-R were enrolled in the failed group. These patients were matched to a control group of 43 patients who underwent primary ACL-R with a minimum follow-up of 24 months. On magnetic resonance imaging, the following parameters were evaluated: transepicondylar distance, lateral and medial femoral condyle widths, tibial plateau width, notch width index, and the ratio of width and height of the femoral notch, ratio between the height and depth of the lateral and medial femoral condyle, lateral and medial posterior tibial slopes, and anterior subluxation of the lateral and medial tibial plateau. Multivariate regression with backward elimination, including only the previously identified significant variables, defined the independent predictors for revision surgery.

RESULTS

The anatomical variables that were significantly different between the 2 study groups were lateral and medial posterior tibial slopes, anterior subluxation of the lateral and medial tibial plateau, medial tibial plateau width, lateral tibial plateau width, medial femoral condyle width, and transepicondylar distance; however, the multivariate regression analysis identified the lateral posterior tibial slope (LTPs), the anterior subluxation of the medial tibial plateau, and the medial femoral condyle width as significant independent predictors (P < .05). The LPTs had the highest coefficient and the highest sensitivity (88%) and specificity (84%) to identify failures when considering the optimal cutoff value of 7.4°.

CONCLUSIONS

Several anatomical parameters have been identified that differ significantly between patients with failed ACL-R and those without a documented failure. The most accurate predictor of ACL failure was an LTPs >7.4°, with a sensitivity of 88% and specificity of 84%. Surgeons should consider measuring LTPs during preoperative assessment of ACL-injured patients, and patients with values >7.4° should be considered at high risk of ACL-R failure.

LEVEL OF EVIDENCE

Level III retrospective prognostic trial.

The Pivot Shift: Current Experimental Methodology and Clinical Utility for Anterior Cruciate Ligament Rupture and Associated Injury

PURPOSE OF REVIEW

The purpose of this manuscript is to (1) examine the history, techniques, and methodology behind quantitative pivot shift investigations to date and (2) review the current status of pivot shift research for its clinical utility for management of anterior cruciate ligament (ACL) rupture with associated injuries including the anterolateral complex (ALC).

RECENT FINDINGS

The pivot shift is a useful physical exam maneuver for diagnosis of rotatory instability related to ACL tear. Recent evidence suggests that the pivot shift is multifactorial and can be seen in the presence of ACL tear with concomitant injury to secondary stabilizers or with predisposing anatomical factors. The presence of a pivot shift post-operatively is associated with poorer outcomes after ACL reconstruction. Recent clinical and biomechanical investigations can help guide clinicians in utilizing pivot shift in diagnosis and surgical planning. Further research is needed to clarify optimal management of ALC in addition to ACL injury.

The lateral femoral notch sign: a reliable diagnostic measurement in acute anterior cruciate ligament injury

PURPOSE

To describe the validity and inter- and intra-observer reliability of the lateral femoral notch sign (LFNS) as measured on conventional radiographs for diagnosing acute anterior cruciate ligament (ACL) injury.

METHODS

Patients (≤ 45 years) with a traumatic knee injury who underwent knee arthroscopy and had preoperative radiographs were retrospectively screened for this case-control study. Included patients were assigned to the ACL injury group (n = 65) or the control group (n = 53) based on the arthroscopic findings. All radiographs were evaluated for the presence, depth and location of the LFNS by four physicians who were blind to the conditions. To calculate intra-observer reliability, each observer re-assessed 25% of the radiographs at a 4-week interval.

RESULTS

The depth of the LFNS was significantly greater in ACL-injured patients than in controls [median 0.8 mm (0-3.1 mm) versus 0.0 mm (0-1.4 mm), respectively; p = 0.008]. The inter- and intra-observer reliabilities of the LFNS depth were 0.93 and 0.96, respectively. Secondary knee pathology (i.e., lateral meniscal injury) in ACL-injured patients was correlated with a deeper LFNS [median 1.1 mm (0-2.6 mm) versus 0.6 mm (0-3.1 mm), p = 0.012]. Using a cut-off value of 1 mm for the LFNS depth, a positive predictive value of 96% was found.

CONCLUSION

This was the first study to investigate the inter- and intra-observer agreement of the depth and location of the LFNS. The depth of the LFNS had a very high predictive value for ACL-injured patients and could be used in the emergency department without any additional cost. A depth of > 1.0 mm was a good predictor for ACL injury. Measuring the depth of the LFNS is a simple and clinically relevant tool for diagnosing ACL injury in the acute setting and should be used by clinicians in patients with acute knee trauma.

LEVEL OF EVIDENCE

Diagnostic study, level II.