Comparative reproducibility of TELOS™ and GNRB® for instrumental measurement of anterior tibial translation in normal knees

DYNEELAX Robotic Arthrometer Reliability and Feasibility on Healthy and Anterior Cruciate Ligament Injured/Reconstructed Persons

Background

Anterior cruciate ligament (ACL) injuries are commonly assessed using clinical examination and magnetic resonance imaging, but these methods have limitations in reproducibility and quantification. Instrumented laxity measurements using devices, like the DYNEELAX®, offer an alternative approach. However, to date, there is no human data on the DYNEELAX® and the reliability of these devices remains a subject of debate, and there is no consensus on appropriate knee tightening levels for testing. We hypothesized that the DYNEELAX®, with standardized knee tightening, would provide reliable measurements of knee laxity in adult volunteers.

Methods

This prospective cohort study involved 48 pain-free adult volunteers. Laxity measurements were taken using a robotic-type motorized instrument (DYNEELAX®) on two separate occasions, at least 1 h and no more than 8 h apart, with knee tightening forces of 90 N ± 5 N. Metrics of anterior tibial translation and internal/external tibial axial rotations were recorded.

Results

The device displayed excellent intrarater reliability for all the metrics, with intraclass correlation coefficients ranging from 0.91 to 0.96. Anterior translation exhibited the highest reliability (intraclass correlation coefficient = 0.96), with a minimum detectable change of 0.83 mm.

Conclusions

DYNEELAX® is reliable in measuring knee laxity in adult volunteers when using standardized stabilizing knee tightening forces of 90 ± 5 N. The most sensitive measurement parameters (in terms of minimum detectable change as a proportion of the observed range) were anterior translation (in mm) at 150 N and secondary compliance.

Anatomic versus Low Tibial Tunnel in Double-Bundle Posterior Cruciate Ligament Reconstruction: Clinical and Radiologic Outcomes with a Minimum 2-Year Follow-Up

There is currently no consensus on the optimal placement of the tibial tunnel for double-bundle posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to compare the clinical and radiologic outcomes of double-bundle PCL reconstruction utilizing anatomic versus low tibial tunnels. We conducted a retrospective cohort study involving patients who underwent double-bundle PCL reconstruction between Jan 2019 and Jan 2022, with a minimum follow-up of 2 years (n = 36). Based on the tibial tunnel position on postoperative computed tomography, patients were categorized into two groups: anatomic placement (group A; n = 18) and low tunnel placement (group L; n = 18). We compared the range of motion, stability test, complications, and side-to-side differences in tibial posterior translation using kneeling stress radiography between the two groups. There were no significant differences between the groups regarding clinical outcomes or complication rates. No significant differences in the posterior drawer test and side-to-side difference on kneeling stress radiography (2.5 ± 1.2 mm in group A vs. 3.7 ± 2.0 mm in group L; p = 0.346). In conclusion, the main findings of this study indicate that both anatomic tunnel and low tibial tunnel placements in double-bundle PCL reconstruction demonstrated comparable and satisfactory clinical and radiologic outcomes, with similar overall complication rates at the 2-year follow-up.

Influence of hamstring stiffness on anterior tibial translation after anterior cruciate ligament rupture

BACKGROUND

There is a correlation between the hamstring stiffness and the decrease of anterior tibial translation in athletic patients with healthy knees. This observation could question the clinical reliability of the Lachman-Trillat test to detect complete ACL ruptures in patients with an important hamstring stiffness. This study aims to determine if anterior tibial translation is correlated with hamstring stiffness in patients with complete ACL rupture.

METHODS

This is a prospective study including patients with unilateral complete ACL rupture confirmed by MRI. The arthrometer GNRB® was used to measure anterior tibial translation on both knees at 134 N and compute the side-to-side difference. The hamstring stiffness was assessed with the eccentric peak torque using the isokinetic dynamometer CON-TREX. Linear regressions were done between these two parameters on two study groups: one included all patients (GR1), and the other included only isolated ACL injuries without associated lesions (GR2).

RESULTS

Fifty-two patients were included (29 men, 23 women) with an average of 34.9 years old. The mean eccentric peak torque of the hamstrings for pathological knees was 94.9Nm for GR1 and 91.7Nm for GR2. The mean side-to-side difference was 2.42 mm for GR1 and 1.99 mm for GR2. No significant correlations were identified for GR1 (p = 0.66) and GR2 (p = 0.105).

CONCLUSION

No significant linear correlation was found between side-to-side difference measured by GNRB® and hamstring stiffness for pathological knees with complete ACL rupture. These results lead to believe that the Lachman-Trillat clinical test is not influenced by hamstring stiffness.

LEVEL OF EVIDENCE

Prospective study, level of evidence IV.

Influence of a posteromedial meniscocapsular injury on the knee anterior laxity. A cadaveric study

PURPOSE

The number of anterior cruciate ligament (ACL) injuries has considerably increased in the recent years, especially in young adults and adolescents. Associated meniscal tears increase anterior and rotary laxity. Posterior peripheral meniscocapsular tear of medial meniscus is also called ramp lesion. Prevalence of 9% to 17% in adults and up to 23% in pediatric population has been reported. The aim of this study was to determine anterior laxity of cadaveric ACL-deficient knees with several size of ramp lesions.

METHODS

Fresh cadaveric knees were explored. Major osteoarthritis and/or ACL and meniscal tears on arthroscopy were exclusion criteria. Mean age at death was 86 years old. Dynamic laximetry with GNRB® device was made in several conditions: Knee prior to any procedure, after arthroscopic exploration, after ACL section, and then after increasing sizes of ramp lesions up to 30 mm. Anteroposterior laxity was measured with 2 loading forces successively (134N and 200N).

RESULTS

After ACL section only, tibiofemoral joint anterior laxity was significantly increased. Mean increase was 156% regardless of the loading force. No statistical laxity difference was found between knees with ACL section only and knees with ACL and meniscal section for any size of ramp lesions. Increasing size of ramp lesion was not correlated with increasing of laxity.

CONCLUSION

We could not find a threshold size of ramp lesion which increases knee anterior laxity. We were not able to determine a threshold recommending a ramp lesion repair.

A non-weight bearing protocol after ACL reconstruction improves static anterior tibial translation in patients with elevated slope and increased weight bearing tibial anterior translation

PURPOSE

Aim of this study is to evaluate the impact of a non-weight bearing (NWB) protocol within 21 post-operative days after anterior cruciate ligament (ACL) reconstruction on static and dynamic anterior tibial translations (SATT and DATT, respectively). The hypothesis is that delayed WB would improve ATT at 9 months follow-up.

METHODS

A series of patients treated with ACL reconstruction was retrospectively reviewed, comparing a group with immediate post-operative weight bearing (WB group) and a group without post-operative weight bearing (NWB group). The NWB protocol was applied to patients with posterior tibial slope (PTS) ≥ 12°, pre-operative SATT ≥ 5 mm, and/or meniscal lesions of root or radial type. SATT, and PTS were measured on 20° flexion monopodal lateral x-rays, while DATT on Telos™ x-rays at pre-operative and 9-months follow-up.

RESULTS

One hundred seventy-nine patients were included (50 NWB group, 129 WB group). The SATT worsened in the WB group with a mean increase of 0.7 mm (SD 3.1 mm), while in the NWB group, the SATT improved with a mean decrease of 1.4 mm (SD 3.1 mm) from the pre-operative to 9 months' follow-up (p < 0.001). The side-to-side Telos™ evaluation showed a significant improvement in DATT within both the groups (p < 0.001), but there was no difference between the two groups (p = 0.99).

CONCLUSION

The post-operative protocol of 21 days without WB led to an improvement in SATT at 9 months without an influence on DATT, and it is recommended for patients with a SATT ≥ 5 mm and/or a PTS ≥ 12° as part of an "à la carte" approach to ACL reconstruction.

LEVEL OF EVIDENCE

Level IV, Retrospective case series.

GNRB® laximeter with magnetic resonance imaging in clinical practice for complete and partial anterior cruciate ligament tears detection: A prospective diagnostic study with arthroscopic validation on 214 patients

BACKGROUND

Accurate diagnosis of anterior cruciate ligament (ACL) injury is not always obtained with magnetic resonance imaging (MRI). Other tools, such as the GNRB® arthrometer, help to accurately identify the type of ACL tear. The aim of this study was to show that the GNRB® could be a relevant complementary solution to MRI in ACL injuries detection.

METHODS

A prospective study performed between 2016 and 2020 included 214 patients who had undergone knee surgery. The study compared sensitivity/specificity pairs of MRI and the GNRB® at 134 N to detect healthy ACL, partial and complete ACL tears. Arthroscopies were the 'gold standard'. Forty-six patients had a healthy ACL with associated knee lesions, 168 patients had ACL tears where 107 were complete tears and 61 were partial tears.

RESULTS

For healthy ACL, MRI scored 100% for sensitivity (SE) and 95% for specificity (SP), and the GNRB® scored SE 95.65% and SP 97.5% at 134 N. For complete ACL tears, MRI scored 80.81% for sensitivity (SE) and 64.49% for specificity (SP), and the GNRB® scored SE 77.78% and SP 85.98% at 134 N. For partial tears, MRI scored SE 29.51% and SP 88.97%, and the GNRB® scored SE 73.77% and SP 85.52% at 134 N.

CONCLUSION

GNRB® sensitivity and specificity were equivalent to those of MRI for healthy ACL and complete ACL tear detection. However, MRI had some difficulty in detecting partial ACL tears compared with the GNRB® which showed better sensitivity.

Intra-rater reliability of the knee arthrometer GNRB® for measuring knee anterior laxity in healthy, active subjects

Background

Arthrometers are used to assess knee anterior laxity and to evaluate the integrity of the anterior cruciate ligament. Assessment of knee anterior laxity is crucial part of the clinical examination. The aim of this study was to investigate the intra-rater reliability of the GNRB® in healthy subjects.

Methods

In the study participated 97 subjects and two measurements using a GNRB® arthrometer were performed. Males were tested two times one week a part. Females were tested two times within 24 h. Measurements were performed at the following forces 134 N, 134 N, 150 N, 200 N, and 200 N. To evaluate the reliability of GNRB® measurements an intraclass correlation coefficient was calculated.

Results

Intra-rater reliability of the GNRB® measurements is good for 134 N on the left knee (ICC = 0.848) and the right knee (ICC = 0.788) and for 200 N on the left knee (ICC = 0.805) and the right knee (ICC = 0.756).

Conclusion

The GNRB® knee arthrometer has good intra-reliability for measurements at the 134 N and 200 N forces. Reliability can be increased with the standardize position of the subject, the stabilization of the patella and standardize measurement protocol.

The validity of the Ligs digital arthrometer at different loads to evaluate complete ACL ruptures

Objective: The Ligs Digital Arthrometer is a recently launched versatile arthrometer that can be used for the quantitative assessment of knee and ankle joint laxity. This study aimed to evaluate the validity of the Ligs Digital Arthrometer for the diagnosis of complete anterior cruciate ligament (ACL) ruptures at different loads.

Materials and Methods: From March 2020 to February 2021, we included 114 normal subjects and 132 subjects diagnosed with complete ACL ruptures by magnetic resonance imaging (MRI) and eventually confirmed by arthroscopy in the study. Anterior knee laxity was independently measured by the same physical therapist using the Ligs Digital Arthrometer. Recorded anterior knee laxity and calculated the side-to-side difference (SSD) at 30, 60, 90, 120, and 150 N loads, respectively. The receiver operating characteristic (ROC) curve was used to determine the optimal laxity threshold, and the diagnostic value was evaluated by the area under the curve (AUC).

Results: The demographic data of the subjects were comparable between the two groups (p &gt; 0.05). The mean values of anterior knee laxity measured by the Ligs Digital Arthrometer between the complete ACL ruptures group and the control group were significantly different at 30, 60, 90, 120, and 150 N loads (p &lt; 0.001 for all). According to the results of ROC curve analysis, the optimal laxity threshold for the diagnosis of complete ACL ruptures was 1.1 mm SSD (Se = 66.7%, Sp = 69.3%) at 30 N, 1.3 mm (Se = 74.2%, Sp = 82.5%) at 60 N, 1.6 mm (Se = 79.5%, Sp = 94.7%) at 90 N, 1.9 mm (Se = 84.1%, Sp = 92.1%) at 120 N and 2.1 mm (Se = 85.6%, Sp = 91.2%) at 150 N. The AUC order at different loads from high to low was 150 N (0.948 [0.923–0.973])&gt;120 N (0.933 [0.903–0.963])&gt;90 N (0.902 [0.862–0.943])&gt;60 N (0.846 [0.799–0.893])&gt;30 N (0.720 [0.657–0.783]).

Conclusion: The Ligs Digital Arthrometer proved to be of high diagnostic value in complete ACL ruptures at 90 N, 120 N, and 150 N loads. The diagnostic value improved with the increase of load in a certain range. Based on the results of this study, as a portable, digital and versatile new arthrometer, the Ligs Digital Arthrometer was a valid and promising tool for diagnosing complete ACL ruptures.

Outcomes of Combined Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction According to GNRB Arthrometer Measurement

Background and Objectives: To investigate the prognosis of combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction, we used a GNRB (Genourob, Laval, France) arthrometer to measure surgical outcomes. Materials and Methods: This retrospective study reviewed patients who underwent combined ACL and ALL reconstruction and had a minimum follow-up of 2 years. Subjective outcomes, namely the International Knee Documentation Committee (IKDC) evaluation form scale scores and Lysholm scores, were evaluated preoperatively and postoperatively. We used a GNRB arthrometer to test the side-to-side laxity under pressures of 134 and 200 N, and we calculated the differential of the slope of the curves. We also recorded complications. Results: Our study examined 18 patients (mean age: 30.56 ± 8.9 years, range: 19-53) with a mean follow-up of 27.37 ± 3.4 months (range: 24-36). Both Lysholm and IKDC scores were significantly improved following the operation. The GNRB arthrometer measured mean anteroposterior laxity side-to-side as 0.76 ± 0.78 mm and 0.82 ± 0.8 mm under pressures of 134 and 200 N, respectively. The mean side-to-side differential slope under 200 N was 3.52 ± 2.17 μm/N. These values indicated that patients displayed no graft tear or low functional knee instability. All patients had a grade 3 pivot shift preoperatively; only two patients had a grade 1 pivot shift postoperatively, with the rest having a negative pivot shift. Conclusions: Our study revealed that combined ACL and ALL reconstruction has an excellent prognosis. GNRB measurement demonstrated excellent stability, and most patients had no residual pivot shift.

Comparison of Rotatory and Sagittal Laxity After Single-Bundle Versus Double-Bundle ACL Reconstruction: Outcomes at 7-Year Follow-up

Background:

Biomechanical studies have shown excellent anteroposterior and rotatory laxity control after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction, but no clinical studies have compared midterm (>5-year) residual laxity between the DB and single-bundle (SB) techniques.

Purpose:

To clinically compare sagittal and rotatory laxities and residual sagittal laxity on the KT-1000 arthrometer between patients treated with an SB ACL reconstruction and those treated with a DB ACL reconstruction at the 7-year follow-up.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 110 patients were included between January 2006 and December 2007. The patients were randomly assigned into 2 groups: those treated with SB ACL reconstruction (n = 63) and those treated with the DB technique (n = 47). All patients were then reviewed at a minimum of 7 years of follow-up; patients with ACL rerupture (n = 3 in the SB group and n = 2 in the DB group) were excluded from the postoperative comparative analysis. Residual anterior laxity (Lachman test), rotatory laxity (pivot-shift test), and sagittal laxity (KT-1000 arthrometer side-to-side difference) were measured and compared between the 2 groups.

Results:

The mean age at surgery was 23.0 ± 5.1 years for the DB group and 28.1 ± 7.0 years for the SB group, and the mean follow-up was 7.4 ± 0.8 years. No statistically significant differences were found between the 2 groups in terms of age, sex, preoperative laxity on KT-1000, preoperative Tegner score, or concomitant meniscal lesions. Residual postoperative laxity via Lachman testing (P < .01), pivot-shift testing (P = .042), and the KT-1000 arthrometer (P < .01) was statistically significantly in favor of DB reconstruction.

Conclusion:

DB ACL reconstruction allowed better control of anterior stability during the evaluation via the Lachman test and via objective measurement on the KT-1000, as well as rotatory stability at a minimum of 7 years of follow-up.

Influence of residual anterior laxity on functional outcomes after anterior cruciate ligament reconstruction

INTRODUCTION

Residual laxity can persist after anterior cruciate ligament (ACL) reconstruction. This increased anterior translation can be measured with a knee arthrometer. Nevertheless, the measurement parameters and functional impact of this residual laxity are not well understood. The aims of this study were to (1) evaluate the effect of applying loads of 134N, 200N and 250N on the measured residual laxity after ACL reconstruction and (2) evaluate the prognostic ability of the various measurement parameters on the functional outcomes.

HYPOTHESIS

After ACL reconstruction, the functional outcomes will be correlated to the postoperative residual laxity.

METHODS

We did a prospective study of 61 recreational athletes who underwent surgical reconstruction of their ACL with the Kenneth-Jones technique between 2016 and 2019. The mean age of these patients was 27±7 years, and most were men (75%). The side-to-side difference in laxity was measured pre- and postoperatively using the GNRB® arthrometer at three load levels: 134N, 200N and 250N. The functional outcomes were determined based on the return to sports and the KOOS, IKDC and ARPEGE scores. The mean follow-up was 30±10 months.

RESULTS

Half the patients had returned to sport at their pre-injury levels, while 25% had returned to a lower level and 25% had stopped doing any physical activity. At 134N, a 1-mm increase in side-to-side difference was associated with a 2-fold higher risk of not returning to sports (OR 2; 95% CI 1.22-3.23; p<0.01). At 200N, a 1-mm increase in side-to-side difference was associated with a 50% higher probability of having a poor/fair ARPEGE score (OR 1.5; 95% CI 1.05-2.02; p=0.02). At 200N, a 4-mm side-to-side difference was the prognostic threshold for failure to return to sports with a positive predictive value of 86% and specificity of 98%.

CONCLUSIONS

This case series found a strong correlation between residual laxity and the functional outcomes after ACL reconstruction. A threshold of 4mm residual laxity evaluated on the GNRB® at 200N was predictive of adverse outcomes and failure to return to sports in our population of recreational athletes.

LEVEL OF EVIDENCE

IV, retrospective study.

The Comparison of Clinical Result between Primary Repair of the Anterior Cruciate Ligament with Additional Internal Bracing and Anatomic Single Bundle Reconstruction-A Retrospective Study

BACKGROUND

The current standard of treatment of anterior cruciate ligament (ACL) is reconstruction (ACLR). This technique has some disadvantages: poor proprioception, donor site morbidity and the inability to restore joint kinematics. ACL repair could be an alternative treatment. The purpose of the study was to compare the stability and the function after ACL primary repair versus single-bundle ACLR.

METHODS

In a retrospective study, 12 patients underwent primary ACL repair with internal bracing, 15 patients underwent standard ACLR. Follow-up examinations were evaluated at up to 2 years postoperatively. One patient in the ACL repair group was lost to follow-up due to re-rupture. The absolute value of anterior tibial translation (ATT) and the side-to-side difference in the same patient (ΔATT) were evaluated using the GNRB arthrometer. The Lysholm knee scoring was obtained. Re-ruptures and other complications were recorded.

RESULTS

Anterior tibial translation (ATT) was significantly decreased in the ACL repair group compared with the ACLR group (5.31 mm vs. 7.18 mm, respectively; p = 0.0137). Arthrometric measurements demonstrated a mean side-to-side difference (ΔATT) 1.87 (range 0.2 to 4.9) mm significantly decreased compared to ACLR 3.36 (range 1.2-5.6 mm; p = 0.0107). The mean Lysholm score was 85.3 points in the ACL repair group and 89.9 in ACLR group. No significant differences between ACL repair and ACLR were found for the Lysholm score. There was no association between AP laxity and clinical outcomes. There were two complications in the internal bracing group: one patient had re-rupture and was treated by ACLR, another had limited extension and had arthroscopic debridement.

CONCLUSIONS

Anterior tibial translation was significantly decreased after ACL repair. Additionally, the functional results after ACL repair with internal bracing were comparable with those after ACLR. It should be noted that the two complications occurred. The current study supports further development of ACL repair techniques.

No significant improvement in neuromuscular proprioception and increased reliance on visual compensation 6 months after ACL reconstruction

Purpose

To determine the contributions of proprioceptive and visual feedbacks for postural control at 6 months following ACLR, and to determine their associations with knee laxity, isokinetic tests and clinical scores.

Study design

Level IV, Case series.

Methods

Fifty volunteers who received ACLR between May 2015 and January 2017 were prospectively enrolled, and at 6 months following ACLR, postural stability was assessed. Somatosensory ratios (somatic proprioception), and visual ratios (visual compensation), were calculated to evaluate the use of sensory inputs for postural control. Univariable regression analyses were performed to determine associations of somatosensory and visual ratios with knee laxity, isokinetic tests and clinical scores.

Results

At 6 months following ACLR, the somatosensory ratio did not change, while the visual ratio decreased significantly from 5.73 ± 4.13 to 3.07 ± 1.96 (p = 0.002), indicating greater reliance on visual cues to maintain balance. Univariable analyses revealed that the somatosensory ratio was significantly lower for patients who performed aquatic therapy (β = -0.50; p = 0.045), but was not associated with knee laxity, muscle strength or clinical scores. An increased visual ratio was associated with patients who received hamstrings tendon autografts (β = 1.32; p = 0.049), but was not associated with knee laxity, muscle strength or clinical scores.

Conclusion

At 6 months following ACLR, visual ratios decreased significantly, while somatosensory ratios did not change. This may suggest that there is little or no improvement in neuromuscular proprioception and therefore greater reliance on visual cues to maintain balance. The clinical relevance of this study is that posturography can provide useful information to help research following ACLR and to predict successful return to play.

Is quadruple semitendinosus tendon strands autograft a better choice than hamstring autograft for anterior cruciate ligament reconstruction? A comparative study with a mean follow-up of 3 years

PURPOSE

The purpose of this study was to compare the clinical outcomes of ST4 with those of STGs with a minimum follow-up of 3 years. The hypothesis was that functional outcomes of the ST4 technique are at least as good as those of the STG technique.

STUDY DESIGN

Cohort study. Level of evidence, 3 METHODS: Eighty-seven consecutive patients underwent isolated ACL reconstruction, 50 with the ST4 and 37 with STG. At the femoral side for both groups, the system of the fixation of the graft used a cortical fixation support and at the tibial side the group STG used an interference screw and the ST4 group used a tape locked system fixed by an interference screw. Clinical results were compared: IKDC score, KT-1000 arthrometry, radiologic evaluation of the differential laxity, as well as the Tegner score and the KOOS score.

RESULTS

Two patients had a rerupture (STG), one in the ST4 group. The analysis of the subjective clinical results showed no statistically significant difference between the 2 groups. Differential laximetry was 0.7 mm ± 0.4 (0 to 2 mm) for the ST4 group and 1.6 ± 0.5 mm (0 to 3 mm) for the STG group with a statistically significant difference in favor of the ST4 group (p < 0.05). Age, sex, and presence of meniscal lesions were the factors influencing the KOOS score.

CONCLUSION

This study comparing the clinical and laximetric results at the minimum 3-year follow-up of 2 ACL reconstruction techniques (ST4 vs STG) confirms the working hypothesis with an overall better score for the ST4 group.

Joint laxity and graft compliance increase during the first year following ACL reconstruction with short hamstring tendon grafts

PURPOSE

Evaluating joint laxity and graft compliance after ACL surgery may be used to quantify biomechanical graft properties during the ligamentization process. This study aimed to analyse the evolvement of joint laxity and graft compliance of short hamstring tendon grafts after ACL reconstruction (ACLR).

METHODS

Forty-seven patients that underwent ACLR were retrospectively enrolled. Joint laxity was quantified with a GNRB^® arthrometer before surgery, then at 15 days, at 1/3/6/9 months (M1-M9), at 1 year postoperatively and then again at the last mean follow-up (FU) of 14.7 ± 3.0 months. The side-to-side laxity difference (ΔL in mm) was measured at 30 and 60 N at every FU, additionally at 90 N from M3 on and at 134 N from M6 on. The side-to-side compliance difference (ΔC in µm/N) was calculated for each graft.

RESULTS

Mean ΔL and ΔC decreased significantly between preoperative and M1 for all applied forces (at 30 N, ΔL: 0.8 mm, p < 0.0001; ΔC: 25.9 µm/N, p < 0.001). Between M1 and M9, ΔL increased significantly at 30 N (p = 0.02) and 60 N (p < 0.001), while ΔC increased by 15.2 µm/N at 30 N (p = 0.003) and 14.9 µm/N at 60 N (p = 0.001). Between M9 and the last FU, there were no significant differences for ΔL and ΔC.

CONCLUSION

Joint laxity and graft compliance evolve during the first postoperative year with a phase between the first and ninth postoperative month of relative weakness. According to the established evolvement profile, return to pivoting or contact sports should be considered only after stabilization of joint laxity and graft compliance.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.

Clinical and Functional Outcomes of Anterior Cruciate Ligament Reconstruction at a Minimum of 2 Years Using Adjustable Suspensory Fixation in Both the Femur and Tibia: A Prospective Study

Background:

The success of anterior cruciate ligament (ACL) reconstruction requires reliable and rigid graft fixation. Cortical suspensory fixation (CSF) devices have become an acceptable alternative to interference screws for soft tissue ACL grafts. However, CSF devices have been reported to be associated with tunnel widening and increased postoperative anterior laxity compared with interference screw fixation. Adjustable CSF devices were introduced to avoid these problems but have been associated with graft lengthening and inconsistent outcomes.

Purpose:

To (1) report the side-to-side difference (SSD) in anterior laxity at 150 N, clinical scores, and failure rates 2 years after ACL reconstruction with 4-strand semitendinosus autografts using an adjustable CSF device and (2) determine the preoperative factors associated with clinical outcomes.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

A total of 131 patients who had undergone primary ACL reconstruction, performed with 4-strand semitendinosus grafts that were secured using Pullup adjustable-length CSF devices with femoral and tibial fixation techniques, were prospectively enrolled in this study; 34 patients were excluded because of contralateral instability or ipsilateral knee injuries that required additional surgery. This left a cohort of 97 patients who were evaluated preoperatively and at 6, 12, and 24 months. The evaluation consisted of measuring the SSD in anterior laxity and patient-reported outcome scores (International Knee Documentation Committee [IKDC] and Lysholm scores). Regression analyses were performed to determine associations between these outcomes and 9 preoperative variables.

Results:

Only 2 patients could not be reached, 2 could not be evaluated because of contralateral ACL tears, and 2 had graft failure. At 2-year follow-up, the remaining 91 patients had a mean SSD in anterior laxity of 0.8 ± 1.8 mm (range, –4.2 to 5.3 mm), mean IKDC score of 87.6 ± 10.6 (range, 43.7-100.0), and mean Lysholm score of 90.8 ± 9.3 (range, 56.0-100.0). At final follow-up, compared with knees with partial ruptures, those with complete ruptures had equivalent laxity (P = .266) and Lysholm scores (P = .352) but lower IKDC scores (P = .009). Multivariable regression revealed that the IKDC score decreased with increased preoperative laxity (β = –1.35 [95% CI, –2.48 to –0.23]; P = .019).

Conclusion:

The novel adjustable-length CSF device produced satisfactory anterior laxity and clinical outcomes, with a failure rate of 2.1%, which compare favorably with those reported for nonadjustable CSF devices.

MRI evaluation of the ACL remnant tissue in ACL-deficient knee

PURPOSE

To clarify the relationship between anterior cruciate ligament (ACL) remnant tissue at the time of surgery and preoperative evaluation of ACL-injured knee.

METHODS

A total of 123 patients were enrolled and classified into four groups based on the classification of ACL remnant tissue. To quantify the signal-noise quotient (SNQ), five regions of interest (ROIs), such as tibial, mid, femoral ACL remnant, tendon of quadriceps femoris to normalize the signal intensity of ACL remnant tissue, and background measurements, were measured. Preoperative side-to-side difference (SSD) and SNQ were analyzed.

RESULTS

Significant differences were observed in preoperative SSD of the four groups ( p = 0.021), and a post hoc analysis revealed that SSD in Crain type 2 was significantly smaller than that in Crain type 4 ( p = 0.014). SSD in Crain type 3 was also significantly smaller than that in Crain type 4 ( p = 0.0030). There were significant differences in SNQ at the tibial, mid, and femoral portion in Crain types 2 and 3 ( p < 0.001); SNQ at the tibial portion in Crain type 2 was significantly lower than that at the mid portion ( p = 0.024); and SNQ at the tibial portion in Crain type 3 was significantly lower than that at the mid portion ( p = 0.016). Furthermore, significant differences were observed in SNQ at the tibial portions in the four groups ( p = 0.034), and SNQ at the tibial portions in Crain type 2 was significantly lower than that in Crain type 1 ( p = 0.044). Also, SNQ at the tibial portions in Crain type 3 was significantly lower than that in Crain type 1 ( P = 0.035).

CONCLUSION

The femoral attachment of the ACL remnant tissue may influence the SNQ of the tibial remnant tissue and the stability of the ACL-injured knee.

Diagnostic Tools for Acute Anterior Cruciate Ligament Injury: GNRB, Lachman Test, and Telos

Purpose

The purpose of this study is to compare the accuracy of the GNRB arthrometer (Genourob), Lachman test, and Telos device (GmbH) in acute anterior cruciate ligament (ACL) injuries and to evaluate the accuracy of each diagnostic tool according to the length of time from injury to examination.

Materials and Methods

From September 2015 to September 2016, 40 cases of complete ACL rupture were reviewed. We divided the time from injury to examination into three periods of 10 days each and analyzed the diagnostic tools according to the time frame.

Results

An analysis of the area under the curve (AUC) of a receiver operating characteristic curve showed that all diagnostic tools were fairly informative. The GNRB showed a higher AUC than other diagnostic tools. In 10 cases assessed within 10 days after injury, the GNRB showed statistically significant side-to-side difference in laxity (p＜0.001), whereas the Telos test and Lachman test did not show significantly different laxity (p=0.541 and p=0.413, respectively).

Conclusions

All diagnostic values of the GNRB were better than other diagnostic tools in acute ACL injuries. The GNRB was more effective in acute ACL injuries examined within 10 days of injury. The GNRB arthrometer can be a useful diagnostic tool for acute ACL injuries.

Prospective comparative study of knee laxity with four different methods in anterior cruciate ligament tears

BACKGROUND AND PURPOSE

Anterior knee laxity can be evaluated using different devices, the most commonly used being the Telos®, KT1000®, Rolimeter®, and GNRB®. However, the laxity values obtained with these devices have never been compared to one another. As such, the outcomes of studies using these different knee laxity measurement devices may not be comparable. The primary purpose of this study was to determine the side-to-side laxity difference in patients with one ACL-injured knee, using each of these devices, and to compare the values obtained from each. We hypothesized that the measurements of laxity would vary depending on the device used.

METHODS

This was a prospective study. All patients with an ACL injury, in which surgical reconstruction was planned, underwent pre-operative knee laxity measurements using four different devices. The concordance correlation coefficient (CCC) of the results was compared between the four devices.

RESULTS

The study enrolled 52 patients. With regard to the values of the side-to-side differences, the KT1000® and the GNRB® obtained the most similar values (CCC = 0.51, 95% CI 0.37-0.63). The two devices with the lowest correlation were the Telos® and the Rolimeter® (CCC = 0.04, 95% CI - 0.14-0.23). The comparability was considered average for the KT1000® and GNRB® and poor for the other devices.

CONCLUSIONS

The knee laxity devices used in regular practice are not comparable to one another. As a result, caution must be taken when comparing results from studies using these different devices.

Evaluation of reproducibility of robotic knee testing device (GNRB) on 60 healthy knees

Introduction

There is a main concern about the usefulness and the accuracy of the different laximeters. The GnrB device is becoming more popular, but according to the literature it's not clear whether it is fully reliable.

Objective

GNRB laxity measurements are not reproducible for measurement of anterior translation of the tibia.

Material and methods

We analyzed the reproducibility of GNRB measurements in healthy subjects by the Test-Retest method in 2 sessions.

Results

30 pairs of healthy knees were assessed. Test-Retest agreement was poor for both absolute values and for differentials at 134 and 200 N with an intra-class correlation ranging from 0.210 to 0.486. There was a significant differance in anterior tibial translation, in side-to-side difference, according to the patellar pressure.

Conclusion

The reproducibility is found to be poor under optimum conditions of comparability. The patellar pressure influences strongly thelaxity value.

Experimental validation of the GNRB® for measuring anterior tibial translation

INTRODUCTION

The objective of this study was to validate the technique used to measure anterior tibial translation in cadaver knees using the GNRB^® device by comparing it with the gold standard, the OrthoPilot^® navigation system.

HYPOTHESIS

Simultaneous measurement of anterior tibial translation by the GNRB^® and the OrthoPilot^® in the chosen experimental conditions will result in significant differences between devices.

MATERIAL AND METHODS

Five fresh frozen cadavers were used. The knee was placed in 20° flexion. Four calibrated posterior-anterior forces (134N to 250N) were applied. For each applied force, the anterior tibial translation was measured simultaneously by both devices. Two conditions were analyzed: anterior cruciate ligament (ACL) intact and ACL transected. The primary criterion was anterior tibial translation at 250N. The measurements were compared using a paired Student's t-test and the correlation coefficient was calculated. Agreement between the two methods was determined using Bland-Altman plots. Consistency of the measurements was determined by calculating the intraclass correlation coefficient.

RESULTS

For all applied forces and ligament conditions, the mean difference between the GNRB^® and the navigation system was 0.1±1.7mm (n.s). Out of the 80 measurements taken, the difference between devices was less than ±2mm in 66 cases (82%). There was a strong correlation, good agreement and high consistency between the two measurement methods.

DISCUSSION

The differences between the measurements taken by the GNRB^® and the navigation system were small and likely have no clinical impact. We recommend using the GNRB^® to evaluate anterior knee laxity.

LEVEL OF EVIDENCE

II controlled laboratory study.

Anterior cruciate ligament assessment using arthrometry and stress imaging

Arthrometry and stress imaging are useful clinical tools for the objective assessment of anterior cruciate ligament (ACL) integrity. They are most frequently used for the diagnosis of a complete ACL tear when other workup is equivocal, in conjunction with history and clinical exam findings. Other applications include the diagnosis of partial ACL tears, injury prognosis, and post-operative monitoring. However, further studies are needed to validate these uses. Many different devices and techniques exist for objective examination, which have been compared in recent literature. Reliability and validity measures of these methods vary, and often depend upon examiner familiarity and skill. The KT series of devices is the current gold standard for arthrometry, although the newer robotic GNRB device shows promising early results. Newer methods of data interpretation have been developed for stress imaging, and portable technology may impact this field further.