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

Biomechanical alterations during gait following partial ACL injury and the effectiveness of anatomical reconstruction: an in-vitro robotic investigation

Background

The biomechanical alterations of the knee throughout the gait cycle following partial anterior cruciate ligament (ACL) injuries remain unclear.

Purpose

This study aimed to investigate the changes in intra-articular contact mechanics during gait following partial ACL injury and to evaluate whether anatomical single-bundle ACL reconstruction (ACLR) could restore these altered mechanics.

Methods

Seven fresh-frozen cadaveric knee specimens were used to evaluate tibiofemoral joint biomechanics under three ligamentous conditions: intact ACL, anteromedial bundle deficiency (AMD), and single-bundle ACLR. A 6 degree of freedom (DOF) robotic system simulated gait motion using physiological loading conditions derived from human. Biomechanical parameters, including peak contact stress, displacement of contact center of stress (CCS), and regional loading patterns, were analyzed at five key gait cycle stages. Statistical analyses were performed using repeated-measures ANOVA and paired t-tests, with significance set at p < 0.05.

Results

AMD knees demonstrated a slight posterior shift in the CCS (<2 mm) during the stance phase, with significant increases in medial compartment regional loading at heel strike (4.11 ± 1.5 N, p = 0.04) and terminal stance (6.31 ± 1.35 N, p = 0.048). ACLR knees exhibited greater posterior CCS displacement in the lateral compartment at heel strike (2.73 ± 1.98 mm vs 0.21 ± 1.97 mm, p = 0.022). The sustained posterior shift in CCS will lead to abnormal loading at the posterior horn of the lateral meniscus, potentially accelerating meniscal tears or degeneration and increasing the incidence of lateral osteoarthritis. Additionally, ACLR knees exhibited significant force increases across both compartments, including the lateral compartment at terminal stance (11.91 ± 2.58 N, p = 0.027) and the medial compartment at pre-swing (11.72 ± 2.17 N, p = 0.011).

Conclusion

Anteromedial bundle injury alters medial compartment loading during gait, causing a slight posterior shift of the center of CCS. And that anatomical single-bundle ACLR does not fully replicate the native anterior cruciate ligament's biomechanical function.

No difference in ACL revision rates between hamstring and patellar tendon autograft in patients with ACL-R and a concurrent meniscal injury irrespective of meniscal treatment

PURPOSE

The aims of this study were to compare (1) the rate of anterior cruciate ligament (ACL) revision and (2) subjective knee function using the Knee injury and Osteoarthritis Outcome Score (KOOS) between isolated ACL reconstruction (ACL-R) and ACL-R and concurrent meniscal injury, based on graft selection and meniscal treatment.

METHODS

Data from the Swedish National Knee Ligament Registry were extracted in November 2022 for patients who underwent primary ACL-R. Patients were divided into two main groups based on graft choice: hamstring tendon (HT) or patellar tendon (PT) autograft, with four meniscal sub-groups: no injury, resection, repair or left in situ. The primary outcome was the rate of ACL revision within 5 years of primary ACL-R, and the secondary outcome was subjective knee function measured with the mean KOOS subscale scores and the rate of patients achieving a patient-acceptable symptom state (PASS) at the 1-, 2- and 5-year follow-up.

RESULTS

The analysis of ACL revision was performed on 45,656 patients, and 7639 patients for the analysis of subjective knee function. The overall rate of ACL revision was 2.4% and 4.9% at 2 and 5 years, respectively. There were no differences in the rate of ACL revision within 5 years of primary surgery irrespective of graft choice or meniscal injury treatment. Patients with ACL-R and concurrent meniscal resection or meniscal injury left in situ achieved a PASS at the 1 (∆ = -11.3% to -29.5%), 2 (∆ = -12.7% to -40.3%) and 5-year (∆ = -12.0% to -30.6%) follow-up to a greater extent when receiving HT autograft compared to PT autograft.

CONCLUSION

Graft selection was not associated with ACL revision in patients with ACL-R and concurrent meniscal injury, regardless of meniscal injury treatment. Superior subjective knee function was reported by patients who underwent ACL-R with HT autograft compared with PT autograft where the injured meniscus was resected or left in situ.

LEVEL OF EVIDENCE

Level III.

Lateral meniscus root tear in anterior cruciate ligament injured patients is not associated with increased rotatory knee laxity: A quantitative pivot shift analysis

OBJECTIVES

Biomechanical investigations conducted in vitro have elucidated the detrimental impact of lateral meniscus posterior root (LMPR) tears on knee contact pressures in the anterior cruciate ligament (ACL)-injured knee. Nevertheless, the influence of LMPR tears on the kinematics of ACL-injured patients remains ambiguous. The purpose of this study was to assess the impact of LMPR tears on anteroposterior and rotatory knee laxity employing a clinically validated quantitative pivot shift (QPS) analysis system.

METHODS

Patients with ACL injury recruited in a prospective ACL registry spanning from 2012 to 2020 were retrospectively screened for eligibility. Criteria for inclusion encompassed complete primary ACL tears, absence of concurrent ligamentous or osseous injuries requiring operative treatment, and no prior knee surgeries. Patients were assigned to two cohorts based on the presence (LMPR+) or absence (LMPR-) of an LMPR tear concomitant with ACL injury. Each patient underwent a standardized PS test, measurement of anterior tibial translation (ATT) (mm) using the Rolimeter, and QPS (mm) with a tablet-based image analysis system (PIVOT App). Comparative analyses of categorical variables were performed using the Fisher exact and Chi-square tests, while non-normally distributed continuous variables were compared between groups with the Mann-Whitney U test. Alfa was set at 0.05.

RESULTS

A total of 99 patients were included in the study, of which 22 were assigned to the LMPR+ and 77 to the LMPR- group. Tear depth was considered partial in 13 (59%) patients and full in 9 (41%) patients. The prevalence of medial meniscus tears was greater in the LMPR+ (n ​= ​16, 73%) compared with the LMPR- (n ​= ​33, 43%) group (p ​= ​0.01). No difference was observed in ATT measured with the Rolimeter (p ​= ​0.63). Similarly, no difference was found in QPS between the LMPR+ (2.3 ​mm) and the LMPR- (1.9 ​mm) group (p ​= ​0.08).

CONCLUSION

Utilizing QPS in this investigation, LMPR tears do not significantly increase ATT or rotatory knee laxity. Consequently, although repairing LMRT associated with ACL injuries may be advisable for minimizing joint stress, their impact on controlling the PS in patients remains uncertain.

LEVEL OF EVIDENCE

III, retrospective comparative study.

All-Inside Anterior Cruciate Ligament Reconstruction Had Clinical Outcome Similar to the Transtibial Technique Except for Improved Side-to-Side Difference and Tegner Activity Scale: A Systematic Review and Meta-analysis

PURPOSE

To compare clinical outcomes of the all-inside technique with the transtibial technique in anterior cruciate ligament reconstruction based on available literature on this topic.

METHODS

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist, we conducted a systematic search for randomized controlled trials and cohort studies. Our comprehensive search encompassed PubMed, Embase, Cochrane Library, and Web of Science. We included randomized controlled trials (RCTs) and cohort studies that compared the 2 techniques with a minimal 1-year follow-up. Two independent authors assessed RCTs using the risk of bias tool developed by the Cochrane Collaboration and evaluated the quality of cohort studies using the Newcastle-Ottawa Scale for Assessing the Quality of Nonrandomized Comparative Trials. The subjective and objective outcomes, complications, and graft failure were obtained. R software was used to perform the analysis.

RESULTS

The present analysis enrolled 9 RCTs (n = 687) and 11 cohort studies (n = 910). After a minimal 1-year follow-up in RCTs, functional outcomes such as International Knee Documentation Committee (IKDC) subjective score, Lysholm score, Tegner activity scale, Knee Society Score, and hop test were found to be similar between 2 techniques. The laxity outcomes, including the IKDC objective grade and pivot-shift test, were suggested to be comparable. There was a significant difference favoring the transtibial technique in terms of side-to-side difference (P = .04; 95% confidence interval [CI], 0.08-0.90). The pooled data from cohort studies indicated equivalent results in terms of IKDC subjective score, Lysholm score, side-to-side difference, IKDC objective grade, complications, and graft failure, with the exception of statistical difference in the Tegner activity scale (P = .03; 95% CI, -0.50 to -0.04).

CONCLUSIONS

Our findings suggest that there is no difference in most outcome scores between the all-inside and transtibial techniques for anterior cruciate ligament reconstruction. There are statistically significant differences in side-to-side difference and Tegner activity scale favoring the all-inside technique.

LEVEL OF EVIDENCE

Level IV, meta-analysis of Level I to IV studies.

Increased Intra-Articular Internal Tibial Rotation Is Associated With Unstable Medial Meniscus Ramp Lesions in ACL-Injured Athletes: An MRI Matched-Pair Comparative Study

Purpose

To analyze internal tibial rotation through magnetic resonance imaging (MRI) of patients with anterior cruciate ligament (ACL) injuries with and without an unstable medial meniscal ramp lesion (MMRL).

Methods

Retrospective analysis of prospectively data was performed to include all consecutive patients who underwent primary ACL reconstruction (ACLR) between January 2022 and June 2022. Two groups, ACLR + unstable MMRL and ACLR without MMRL, were constituted. Propensity score matching analysis was used to limit selection bias. The angle between surgical epicondylar axes (SEAs) and the tangent line of the posterior tibial condyles (PTCs) was measured to analyze the rotational alignment between distal femur and proximal tibia. MMRLs were defined unstable if they were ≥1 cm, if the lesions extend beyond the lower pole of the femoral condyle, and/or if there was displacement into the medial compartment by anterior probing.

Results

Twenty-eight propensity-matched pairs were included. The ACLR + unstable MMRL presented a significantly greater internal rotation of the tibia compared to ACLR without MMRL (P < .001). An internal tibial rotation was associated with unstable ramp lesions in ACL-injured patients (odds ratio [OR], 0.36; 95% CI, 0.25-0.41; P < .0001). If SEA-PTC was 0°, the sensitivity and specificity of the SEA-PTC angle to detect unstable MMRL were respectively 100% (95% CI, 85%-100%) and 18% (95% CI, 8%-36%). Otherwise, if SEA-PTC angle was -10°, the sensitivity and specificity of the SEA-PTC angle to detect unstable MMRL were respectively 43% (95% CI, 27%-61%) and 96% (95% CI, 81%-100%). Bone edema of the posterior medial tibial plateau was significantly associated with unstable ramp lesions (OR, 1.58; 95% CI, 1.21-2.06; P = .029).

Conclusions

Unstable MMRL concomitant to an ACL rupture was associated with an increased tibial internal rotation.

Level of Evidence

Level III, retrospective comparative trial.

Internal Rotation Measurement of the Knee with Polymer-Based Capacitive Strain Gauges versus Mechanical Rotation Measurement Taking Gender Differences into Account: A Comparative Analysis

With the conventional mechanical rotation measurement of joints, only static measurements are possible with the patient at rest. In the future, it would be interesting to carry out dynamic rotation measurements, for example, when walking or participating in sports. Therefore, a measurement method with an elastic polymer-based capacitive measuring system was developed and validated. In our system, the measurement setup was comprised of a capacitive strain gauge made from a polymer, which was connected to a flexible printed circuit board. The electronics integrated into the printed circuit board allowed data acquisition and transmission. As the sensor strip was elongated, it caused a change in the spacing between the strain gauge's electrodes, leading to a modification in capacitance. Consequently, this alteration in capacitance enabled the measurement of strain. The measurement system was affixed to the knee by adhering the sensor to the skin in alignment with the anterolateral ligament (ALL), allowing the lower part of the sensor (made of silicone) and the circuit board to be in direct contact with the knee's surface. It is important to note that the sensor should be attached without any prior stretching. To validate the system, an in vivo test was conducted on 10 healthy volunteers. The dorsiflexion of the ankle was set at 2 Nm using a torque meter to eliminate any rotational laxity in the ankle. A strain gauge sensor was affixed to the Gerdii's tubercle along the course of the anterolateral ligament, just beneath the lateral epicondyle of the thigh. In three successive measurements, the internal rotation of the foot and, consequently, the lower leg was quantified with a 2 Nm torque. The alteration in the stretch mark's length was then compared to the measured internal rotation angle using the static measuring device. A statistically significant difference between genders emerged in the internal rotation range of the knee (p = 0.003), with female participants displaying a greater range of rotation compared to their male counterparts. The polymer-based capacitive strain gauge exhibited consistent linearity across all measurements, remaining within the sensor's initial 20% strain range. The comparison between length change and the knee's internal rotation angle revealed a positive correlation (r = 1, p < 0.01). The current study shows that elastic polymer-based capacitive strain gauges are a reliable instrument for the internal rotation measurement of the knee. This will allow dynamic measurements in the future under many different settings. In addition, significant gender differences in the internal rotation angle were seen.

Various Definitions of Failure Are Used in Studies of Patients Who Underwent Anterior Cruciate Ligament Reconstruction

Purpose

To conduct a literature review to assess the definitions of anterior cruciate ligament reconstruction (ACLR) failure used throughout the orthopaedic literature.

Methods

A systematic search of Embase, Ovid Medline, SPORTDiscus, and Web of Science was conducted by a university librarian to identity level I-IV clinical studies on ACLR failure. Inclusion criteria consisted of patients who underwent ACLR and included a definition of failure of ACLR. Patients who underwent anterior cruciate ligament (ACL) repairs, animal/cadaver studies, review studies, non-English language articles, and non-full text articles were excluded. Failure data were extracted from each study and categorized. Other data that were extracted included follow-up time after ACLR, failure reoperation rate, and failure reoperation procedure. Descriptive statistics was used to analyze the data.

Results

Out of 2,775 studies, 104 (3.75%) met inclusion criteria and were analyzed in this review. The most common definition of ACLR failure included the use of a physical examination, specifically Lachman's test (21/104 [20.2%]), anterior laxity assessment, or a Pivot-Shift test (24/104 [35.2%]) or undergoing or requiring revision ACLR (39/104 [37.5%]). Although some studies used quantitative tests or imaging to help define "failure," others simply defined it as graft rerupture that was otherwise not defined (22/104 [22.5%]). Other common definitions included: the use of imaging (magnetic resonance imaging/radiographs) to confirm graft re-rupture (37/104 [35.6%]), patient-reported outcomes (recurrent instability)/patient reported outcomes measures (International Knee Documentation Committee [IKDC], Knee injury and Osteoarthritis Outcome Score [KOOS], Tegner) (18/104 [17.3%]), and the use of an arthrometer (KT-1000/2000, Rollimeter, or Kneelax) (17/104 [16.3%]). The least common definitions included graft failure or rerupture confirmed by arthroscopy (13/104 [12.5%]) and nonrevision surgery (2/104 [1.0%]). The failure rate of this procedure ranged from 0% to 100% depending on the definition of "failure."

Conclusion

In this study, we found that a variety of definitions of failure are used among studies published in the orthopaedic literature. The most common criteria for failure of ACLR were the results of physical examination tests (35%), the need for undergoing a revision ACLR (36%), and the use of imaging to diagnose the failure (34%). About 17% of studies included in this review used patient-reported outcomes, specifically recurrent instability, or PROMs (IKDC, KOOS, Tegner) in their assessment of failure of ACLR. The least used definitions of "failure" of ACLR included nonrevision ACLR surgery (2%). Although some studies used similar tests or categories in their definition of failure, there were a variety of score and grade cutoff points between them.

Level of Evidence

Level IV, systematic review of Level II-IV studies.

Distal Kaplan fibers and anterolateral ligament injuries are associated with greater intra-articular internal tibial rotation in ACL-deficient knees based on magnetic resonance imaging

PURPOSE

The purpose of the present study was to assess the internal rotation of the tibia on Magnetic Resonance Imaging (MRI) in a series of consecutive athletes with Anterior cruciate Ligament (ACL) tears.

METHODS

Retrospective analysis of prospectively collected data was performed to include all consecutive patients who had undergone primary ACL reconstruction between January 2022 and June 2022. The angle between surgical epicondylar axes (SEA) of the knee and posterior tibial condyles (PTC) was measured. A negative value was defined as internal torsion. KFs and ALL injuries were reported. Analysis of covariance (ANCOVA) was performed to examine the independent associations between SEA-PTC angle and injuries of KFs and ALL adjusted for physical variables (age, gender and body mass index [BMI]). Statistical significance was set at a p-value of < 0.05.

RESULTS

A total of 83 eligible patients were included. The result of multiple linear regression analysis showed that internal tibial rotation was associated with KFs and ALL injuries. The estimated average of SEA-PTC angle in relation to ALL injuries controlling the other variables was -5.49 [95%CI -6.79 - (-4.18)] versus -2.99 [95%CI -4.55 - (-1.44)] without ALL injuries. On the other hand, the estimated average of SEA-PTC angle in relation to KFs lesions controlling the other variables was -5.73 [95%CI -7.04 - (-4.43)] versus -2.75 [95%CI -4.31 - (-1.18)] without KFs injuries.

CONCLUSIONS

KFs and ALL injuries were associated with an increased intra-articular internal tibial rotation in ACL-deficient knees. The measurement of femorotibial rotation on axial MRI could be useful to detect indirect signs of anterolateral complex (ALC) injuries.

Does Rotation and Anterior Translation Persist as Residual Instability in the Knee after Anterior Cruciate Ligament Reconstruction? (Evaluation of Coronal Lateral Collateral Ligament Sign, Tibial Rotation, and Translation Measurements in Postoperative MRI)

Purpose: The aim of this study was to evaluate the presence of residual instability in the knee after ACL reconstruction through the analysis of MRI findings. Methods: This study included patients who underwent isolated ACL reconstruction between December 2019 and December 2021, and had preoperative and postoperative MRI, clinical scores, and postoperative isokinetic measurements. The anterior tibial translation (ATT) distance, coronal lateral collateral ligament (LCL) sign, and femorotibial rotation (FTR) angle were compared preoperatively and postoperatively. The correlation between the changes in preoperative-postoperative measurements and postoperative measurements with clinical scores and isokinetic measurements was examined. The clinical outcomes were compared based on the presence of a postoperative coronal LCL sign. Inclusion criteria were set as follows: the time between the ACL rupture and surgery being 6 months, availability of preoperative and postoperative clinical scores, and objective determination of muscle strength using isokinetic dynamometer device measurements. Patients with a history of previous knee surgery, additional ligament injuries other than the ACL, evidence of osteoarthritis on direct radiographs, cartilage injuries lower limb deformities, and contralateral knee injuries were excluded from this study. Results: This study included 32 patients. After ACL reconstruction, there were no significant changes in the ATT distance (preoperatively: 6.5 ± 3.9 mm, postoperatively: 5.7 ± 3.2 mm) and FTR angle (preoperatively: 5.4° ± 2.9, postoperatively: 5.2° ± 3.5) compared to the preoperative measurements (p > 0.05). The clinical measurements were compared based on the presence of a postoperative coronal LCL sign (observed in 17 patients, not observed in 15 patients), and no significant differences were found for all parameters (p > 0.05). There were no observed correlations between postoperative FTR angle, postoperative ATT distance, FTR angle change, and ATT distance change values with postoperative clinical scores (p > 0.05). Significant correlations were observed between the high strength ratios generated at an angular velocity of 60° and a parameters FTR angle and ATT distance (p-values: 0.028, 0.019, and r-values: -0.389, -0.413, respectively). Conclusions: Despite undergoing ACL reconstruction, no significant changes were observed in the indirect MRI findings (ATT distance, coronal LCL sign, and FTR angle). These results suggest that postoperative residual tibiofemoral rotation and tibial anterior translation may persist; however, they do not seem to have a direct impact on clinical scores. Furthermore, the increase in tibial translation and rotation could potentially negatively affect the flexion torque compared to the extension torque in movements requiring high torque at low angular velocities.

Pivot Shift Syndrome of the Knee

The pivot shift test, in contrast to the Lachman or anterior drawer, is a manually subjective clinical test that simulates the injury mechanism. It is the most sensitive test to determine ACL insufficiency. This paper reviews the history, development, research, and treatment associated with the pivot shift phenomenon which is associated with tearing and loss of function of the knee anterior cruciate ligament. The pivot shift test most closely recapitulates what the symptomatic anterior cruciate ligament deficient patient feels is happening which is an abnormal translation and rotation of the injured joint during flexion or extension. The test is best conducted in the relaxed patient by applying knee flexion, tibial external rotation, and valgus stress. The pivot shift biomechanics and treatment measures are reviewed.

Morphometric MRI Evaluation of Three Autografts Used in Anterior Cruciate Ligament Reconstruction in Athletes

The purpose of the present study was to quantify the morphometric characteristics of three tendon autografts (hamstring tendons (HT), quadriceps tendon (QT), and patellar tendon (PT)) used in anterior cruciate ligament (ACL) reconstruction. For this purpose, knee magnetic resonance imaging (MRI) was obtained in 100 consecutive patients (50 males and 50 females) with an acute, isolated ACL tear without any other knee pathology were used. The level of the physical activity of the participants was determined using the Tegner scale. Measurements of the tendons' dimensions (PT and QT tendon length, perimeter, cross-sectional area (CSA), and maximum mediolateral and anteroposterior dimensions) were performed perpendicular to their long axes. Higher values were recorded as regards the mean perimeter and CSA of the QT in comparison with the PT and the HT (perimeter QT: 96.52 ± 30.43 mm vs. PT: 63.87 ± 8.45 mm, HT: 28.01 ± 3.73 mm, F = 404.629, p < 0.001; CSA QT: 231.88 ± 92.82 mm2 vs. PT: 108.35 ± 28.98 mm2, HT: 26.42 ± 7.15 mm2, F = 342.415, p < 0.001). The length of the PT was shorter in comparison with the QT (53.1 ± 7.8 vs. 71.7 ± 8.6 mm, respectively, t = -11.243, p < 0.001). The three tendons showed significant differences in relation to sex, tendon type, and position as regards the perimeter, CSA, and the mediolateral dimensions but not for the maximum anteroposterior dimension.

Preoperative quantitative pivot shift does not correlate with in vivo kinematics following ACL reconstruction with or without lateral extraarticular tenodesis

PURPOSE

Quantitative pivot shift (QPS) testing using PIVOT technology can detect high- and low-grade rotatory knee instability following anterior cruciate ligament injury or reconstruction (ACLR). The aim of this project was to determine if preoperative QPS correlates with postoperative knee kinematics in the operative and contralateral, healthy extremity following ACLR with or without lateral extraarticular tenodesis (LET) using a highly precise in vivo analysis system. A positive correlation between preoperative QPS and postoperative tibial translation and rotation following ACLR with or without LET in the operative and healthy, contralateral extremity was hypothesized.

METHODS

Twenty patients with ACL injury and high-grade rotatory knee instability were randomized to undergo anatomic ACLR with or without LET as part of a prospective randomized trial. At 6 and 12 months postoperatively, in vivo kinematic data were collected using dynamic biplanar radiography superimposed with high-resolution computed tomography scans of patients' knees during downhill running. Total anterior-posterior (AP) tibial translation and internal-external tibial rotation were measured during the gait cycle. Spearman's rho was calculated for preoperative QPS and postoperative kinematics.

RESULTS

In the contralateral, healthy extremity, a significant positive correlation was seen between preoperative QPS and total AP tibial translation at 12 months postoperatively (r_s = 0.6, p < 0.05). There were no additional significant correlations observed between preoperative QPS and postoperative knee kinematics at 6 and 12 months postoperatively in the operative and contralateral, healthy extremity for combined isolated ACLR and ACLR with LET patients as well as isolated ACLR patients or ACLR with LET patients analyzed separately.

DISCUSSION

The main finding of this study was that there was a significant positive correlation between preoperative QPS and total AP tibial translation at 12 months postoperatively in the contralateral, healthy extremity. There were no significant correlations between preoperative QPS and postoperative in vivo kinematics at 6 and 12 months following ACLR with or without LET. This suggests that QPS as measured with PIVOT technology does correlate with healthy in vivo knee kinematics, but QPS does not correlate with in vivo kinematics following ACLR with or without LET.

The interobserver reliability of clinical relevance in orthopaedic research

PURPOSE

A ratio of observed difference (OD) over the 95% confidence interval (CI) has been shown to be strongly associated with the perceived clinical relevance (CR) of medical research results. The purpose of this study was to evaluate the association between the OD/CI ratio and perceived CR in orthopaedic research.

METHODS

Sixty-seven orthopaedic surgeons completed a survey with 15 study outcomes (mean difference and CI) and were asked if they perceived the findings as clinically relevant. The interobserver reliability of perceived CR and the association between CR and the OD/CI ratio and p-value were assessed.

RESULTS

The interobserver reliability of CR between respondents was moderate (kappa = 0.46, CI 0.45 to 0.48). P-values did not differ between results with and without CR (median difference (MD) - 0.12, CI - 0.74 to 0.0009, p = 0.07). The OD/CI ratio, however, was greater for results with CR (MD 1.01, CI 0.3 to 3.9, p = 0.004). The area under the curve (AUC) for the p-value and OD/CI ratio receiver operating characteristic (ROC) curves was 0.80 (p = 0.01) and 0.97 (p = 0.0003). The cutoff p -value and OD/CI ratio that maximized the sensitivity (SN) and specificity (SP) for CR were 0.001 (SN 80%, SP 80%) and 0.84 (SN 100%, SP 90%). The SN and SP of a p-value cutoff of 0.05 was 100% and 50%.

CONCLUSION

The interobserver reliability of the perceived CR of orthopaedic research findings was moderate. The OD/CI ratio, in contrast to the p-value, was strongly associated with perceived CR making it a potentially useful measure to evaluate research results.

Femur-tibia angle and patella-tibia angle: new indicators for diagnosing anterior cruciate ligament tears in magnetic resonance imaging

Background

Femur-tibia angle (FTA) and patella-tibia angle (PTA) are two MRI measurements that reflect the rotation of the knee joint. The purposes of this study were to assess whether FTA and PTA are associated with ACL tear and to explore their roles in ACL tear diagnosis.

Methods

FTA, PTA, ACL angle and anterior tibial subluxation were compared between the two matched groups: ACL tear group and control group (each n = 20). Diagnostic performance was evaluated in a consecutive 120-patient cohort who underwent MR imaging of the knee and subsequently had arthroscopy. Different measurements were assessed by area under the curve (AUC) of receiver operating characteristic (ROC) curve.

Results

FTA and PTA increased significantly in ACL tears group when compared to the control group (4.79 and 7.36 degrees, respectively, p < 0.05). In distinguishing complete ACL tear, ACL angle had the highest AUC of 0.906 while AUC of PTA and FTA were 0.849 and 0.809. The cutoff of FTA was 80 degrees with a sensitivity of 82% and specificity of 68%, while the cutoff of PTA was 91 degrees with a sensitivity of 82% and specificity of 74%. In distinguishing partial ACL tear, FTA and PTA had the highest AUCs of 0.847 and 0.813, respectively. The calculated cutoff of FTA was 84 degrees with a sensitivity of 90% and specificity of 81%, while the cutoff of PTA was 92 degrees with a sensitivity of 80% and specificity of 77%.

Conclusion

FTA and PTA increased when ACL tears and they might be valuable in diagnosing ACL tears, especially in distinguishing partial ACL tear from intact ACL.

Adult patients with ACL tears have greater tibial internal rotation in MRI compared to adolescent patients

Purpose

To compare the anterior translation and internal rotation of tibia on magnetic resonance imaging (MRI) between adult and adolescent patients with anterior cruciate ligament (ACL) tears.

Methods

Patients who underwent isolated ACL reconstruction from January 2013 to May 2021 were retrospectively reviewed. The exclusion criteria included incomplete data, poor image quality, a prior ACL surgery, and concomitant fractures or other ligament injuries. The enrolled patients were divided into two groups based on their ages: an adult group (age > 19 years) and an adolescent group (15 to 19 years of age). Anterior tibial translation and femorotibial rotation were measured on MRI. A Student’s t-test was used for the statistical analysis comparing the adult and adolescent groups.

Results

A total of 365 patients (279 adults and 86 adolescents) were enrolled in the present study. The anterior tibial translation in the adult group (4.8 ± 4.4 mm) and the adolescent group (5.0 ± 4.2 mm) was not significantly different (p = 0.740). On the other hand, the tibial internal rotation in the adult group (5.6 ± 5.0 degree) was significantly greater compared to the adolescent group (4.2 ± 5.6 degree) (p = 0.030). The intraclass correlation coefficients (ICC) of the measured data from two independent observers showed excellent reliability (0.964 and 0.961 for anterior tibial translation and tibial internal rotation, respectively).

Conclusion

The adult patients with ACL tears exhibited significant greater tibial internal rotation compared to the adolescent patients, whereas the magnitude of the anterior tibial translation was similar in both groups. Care should be taken if clinicians plan to establish the cutoff point values for diagnosis of ACL tears using the femorotibial internal rotation angle.

Association of Ligamentous Laxity, Male Sex, Chronicity, Meniscal Injury, and Posterior Tibial Slope With a High-Grade Preoperative Pivot Shift: A Post Hoc Analysis of the STABILITY Study

Background:

A spectrum of anterolateral rotatory laxity exists in anterior cruciate ligament (ACL)–injured knees. Understanding of the factors contributing to a high-grade pivot shift continues to be refined.

Purpose:

To investigate factors associated with a high-grade preoperative pivot shift and to evaluate the relationship between this condition and baseline patient-reported outcome measures (PROMs).

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A post hoc analysis was performed of 618 patients with ACL deficiency deemed high risk for reinjury. A binary logistic regression model was developed, with high-grade pivot shift as the dependent variable. Age, sex, Beighton score, chronicity of the ACL injury, posterior third medial or lateral meniscal injury, and tibial slope were selected as independent variables. The importance of knee hyperextension as a component of the Beighton score was assessed using receiver operator characteristic curves. Baseline PROMs were compared between patients with and without a high-grade pivot.

Results:

Six factors were associated with a high-grade pivot shift: Beighton score (each additional point; odds ratio [OR], 1.17; 95% CI, 1.06-1.30; P = .002), male sex (OR, 2.30; 95% CI, 1.28-4.13; P = .005), presence of a posterior third medial (OR, 2.55; 95% CI, 1.11-5.84; P = .03) or lateral (OR, 1.76; 95% CI, 1.01-3.08; P = .048) meniscal injury, tibial slope >9° (OR, 2.35; 95% CI, 1.09-5.07; P = .03), and chronicity >6 months (OR, 1.70; 95% CI, 1.00-2.88; P = .049). The presence of knee hyperextension improved the diagnostic utility of the Beighton score as a predictor of a high-grade pivot shift. Tibial slope <9° was associated with only a high-grade pivot in the presence of a posterior third medial meniscal injury. Patients with a high-grade pivot shift had higher baseline 4-Item Pain Intensity Measure scores than did those without a high-grade pivot shift (mean ± SD, 11 ± 13 vs 8 ± 14; P = .04); however, there was no difference between groups in baseline International Knee Documentation Committee, ACL Quality of Life, Knee injury and Osteoarthritis Outcome Score, or Knee injury and Osteoarthritis Outcome Score subscale scores.

Conclusion:

Ligamentous laxity, male sex, posterior third medial or lateral meniscal injury, increased posterior tibial slope, and chronicity were associated with a high-grade pivot shift in this population deemed high risk for repeat ACL injury. The effect of tibial slope may be accentuated by the presence of meniscal injury, supporting the need for meniscal preservation. Baseline PROMs were similar between patients with and without a high-grade pivot shift.

Coronal Lateral Collateral Ligament Sign: A Novel Magnetic Resonance Imaging Sign for Identifying Anterior Cruciate Ligament-Deficient Knees in Adolescents and Summarizing the Extent of Anterior Tibial Translation and Femorotibial Internal Rotation

BACKGROUND

Incompetence of the anterior cruciate ligament (ACL) confers knee laxity in the sagittal and axial planes that is measurable with clinical examination and diagnostic imaging.

HYPOTHESIS

An ACL-deficient knee will produce a more vertical orientation of the lateral collateral ligament (LCL), allowing for the entire length of the LCL to be visualized on a single coronal slice (coronal LCL sign) on magnetic resonance imaging.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

Charts were retrospectively reviewed from April 2009 to December 2017 for all patients treated with ACL reconstruction (constituting the ACL-deficient cohort). A control cohort was separately identified consisting of patients with a normal ACL and no pathology involving the collateral ligaments or posterior cruciate ligament. Patients were excluded for follow-up <2 years, incomplete imaging, and age >19 years. Tibial translation and femorotibial rotation were measured on magnetic resonance images, and posterior tibial slope was measured on a lateral radiograph of the knee. Imaging was reviewed for the presence of the coronal LCL sign.

RESULTS

The 153 patients included in the ACL-deficient cohort had significantly greater displacement than the 70 control patients regarding anterior translation (5.8 vs 0.3 mm, respectively; P < .001) and internal rotation (5.2° vs -2.4°, P < .001). Posterior tibial slope was not significantly different. The coronal LCL sign was present in a greater percentage of ACL-deficient knees than intact ACL controls (68.6% vs 18.6%, P < .001). The presence of the coronal LCL sign was associated with greater anterior tibial translation (7.2 vs 0.2 mm, P < .001) and internal tibial rotation (7.5° vs -2.4°, P = .074) but not posterior tibial slope (7.9° vs 7.9°, P = .973) as compared with its absence. Multivariate analysis revealed that the coronal LCL sign was significantly associated with an ACL tear (odds ratio, 12.8; P < .001).

CONCLUSION

Our study provides further evidence that there is significantly more anterior translation and internal rotation of the tibia in the ACL-deficient knee and proves our hypothesis that the coronal LCL sign correlates with the presence of an ACL tear. This coronal LCL sign may be of utility for identifying ACL tears and anticipating the extent of axial and sagittal deformity.

Predictive Value of the Magnetic Resonance Imaging-Based Coronal Lateral Collateral Ligament Sign on Adolescent Anterior Cruciate Ligament Reconstruction Graft Failure

BACKGROUND

The coronal lateral collateral ligament (LCL) sign is the presence of the full length of the LCL visualized on a single coronal magnetic resonance imaging (MRI) slice at the posterolateral corner of the knee. The coronal LCL sign has been shown to be associated with elevated measures of anterior tibial translation and internal rotation in the setting of anterior cruciate ligament (ACL) tear.

HYPOTHESIS

The coronal LCL sign (with greater anterior translation, internal rotation, and posterior slope of the tibia) will indicate a greater risk for graft failure after ACL reconstructive surgery.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Retrospective review was performed of adolescent patients with ACL reconstruction: a cohort without graft failure and a cohort with graft failure. MRI was utilized to measure tibial translation and femorotibial rotation and to identify the coronal LCL sign. The posterior tibial slope was measured on lateral radiographs. Patient-reported outcomes were collected.

RESULTS

We identified 114 patients with no graft failure and 39 patients with graft failure who met all criteria, with a mean follow-up time of 3.5 years (range, 2-9.4 years). Anterior tibial translation was associated with anterolateral complex injury (P < .001) but not graft failure (P = .06). Internal tibial rotation was associated with anterolateral complex injury (P < .001) and graft failure (P = .042). Posterior tibial slope was associated with graft failure (P = .044). The coronal LCL sign was associated with anterolateral complex injury (P < .001) and graft failure (P = .013), with an odds ratio of 4.3 for graft failure (95% CI, 1.6-11.6; P = .003). Subjective patient-reported outcomes and return to previous level of sport were not associated with failure. Comparison of MRI before and after ACL reconstruction in the graft failure cohort demonstrated a reduced value in internal rotation (P = .003) but no change in coronal LCL sign (P = .922).

CONCLUSION

Our study demonstrates that tibial internal rotation and posterior slope are independent predictors of ACL graft failure in adolescents. Although the value of internal rotation could be improved with ACL reconstruction, the presence of the coronal LCL sign persisted over time and was predictive of graft rupture (without the need to make measurements or memorize values of significant risk). Together, these factors indicate that greater initial knee deformity after initial ACL tear predicts greater risk for future graft failure.

Augmentation of Anatomic Anterior Cruciate Ligament Reconstruction With Lateral Extra-articular Tenodesis Does Not Significantly Affect Rotatory Knee Laxity: A Time Zero, In Vivo Kinematic Analysis

BACKGROUND

The pivot-shift test is used to assess for rotatory knee laxity in the anterior cruciate ligament (ACL)-deficient knee and ACL-reconstructed knee; however, the pivot shift uses a subjective grading system that is limited by variability between examiners. Consequently, quantified pivot shift (QPS) test software (PIVOT iPad application) has been developed and validated to measure the magnitude of rotatory knee laxity during the positive pivot-shift test.

PURPOSE

To employ intraoperative QPS (iQPS) to assess for differences in residual rotatory knee laxity after ACL reconstruction (ACLR) versus ACLR augmented with lateral extra-articular tenodesis (ACLR + LET), and to employ iQPS to determine if ACLR and/or ACLR + LET result in overconstrained knee kinematics when compared with the contralateral knee.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

iQPS was performed in 20 patients by a single surgeon on both the operative and contralateral knees before ACLR. ACLR was augmented with a LET if the lateral compartment tibial translation measured during QPS was greater than or equal to double the amount of lateral tibial compartment translation measured for the contralateral knee. After each reconstruction (ACLR or ACLR + LET), iQPS measurements were performed. iQPS data were compared with the preoperative QPS measurements of the operative and contralateral knees. Postoperative iQPS data were compared with both the preoperative QPS measurements of the operative and contralateral knees with paired samples t tests. Categorical variables were compared using the Fisher exact test.

RESULTS

The mean age in the cohort was 17.3 years (range, 15-24 years). There were no significant differences between the groups in terms of the proportion of male patients (ACLR: 5 male, 5 female vs ACLR + LET: 4 male, 6 female) or age (ACLR: 17.7 ± 3.3 years; 95% CI, 15.4-24.0 vs ACLR + LET: 16.8 ± 2.8 years, 95% CI, 14.8-22.0; P = .999). There were no significant differences between the groups with respect to preoperative QPS performed during examination under anesthesia (ACLR: 4.7 ± 2.0 mm; 95% CI, 3.3-6.1 vs ACLR + LET: 3.6 ± 1.8 mm; 95% CI, 2.3-4.9; P = .2). Both ACLR and ACLR + LET resulted in significant decreases in rotatory knee laxity when compared with preoperative QPS measurements (ACLR: -3.4 ± 1.7 mm; 95% CI, -4.6 to -2.2; P < .001: ACLR + LET: -2.6 ± 1.9 mm; 95% CI, -3.9 to -1.3; P < .002). Moreover, when compared with isolated ACLR, ACLR + LET did not result in a significantly smaller magnitude of change in iQPS between the pre- and postoperative states (P = .3).

CONCLUSION

Both ACLR and ACLR + LET resulted in significant decreases in rotatory knee laxity. The augmentation of ACLR with LET did not change the constraint of the knee with respect to lateral compartment translation as measured during iQPS.