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

BLU-DAT: a new reliable and accurate arthrometer for measuring anterior knee laxity

PURPOSE

Although many arthrometers have been developed to assess anterior knee laxity, reliability and diagnostic accuracy of these devices are still debated. The aim of the present study was to evaluate the validity of a new arthrometer in the outpatient setting, with the hypothesis that it had good validity in terms of reliability and diagnostic accuracy.

METHODS

Seventy-eight subjects (39 with ACL injury and 39 with normal ACL) were tested. ATT was assessed by means of the Lachman test at 30° of flexion with a new testing device (BLU-DAT) under three different loading conditions: 7 kg (69 N), 9 kg (88 N) and maximum (MMT). The tests were performed on both knees to obtain SSD. In the ACL injury group, the tests were performed by two examiners and one of them repeated a second test series. Inter- and intra-observer reliability were assessed with the intraclass correlation coefficients (ICCs) for the average SSD measures. In the normal-ACL group, the analysis was performed with the same testing setup. Side-to-side difference measures of the two groups at every loading condition were compared by Student's t test. Data of test series were dichotomized based on the threshold value of 3-mm SSD as pathological ATT and 2 × 2 contingency tables were used to assess diagnostic accuracy.

RESULTS

The ICCs for intra-observer reliability at 7-kg (69 N), 9-kg (88 N) and MMT measurements were 0.781, 0.855 and 0.913, respectively. The ICC for inter-observer reliability at 7-kg (69 N), 9-kg (88 N) and MMT measurements were 0.701, 0.845 and 0.834, respectively. Comparison between the two groups showed a significant mean difference ranging from 3.4 mm for 7-kg (69 N) load to 4.6 mm for MMT. Overall accuracy ranged from 84.6% for 7-kg load to 98.7% for MMT.

CONCLUSION

The BLU-DAT has proven to be an instrument with good intra- and inter-observer reliability and very good accuracy in the diagnosis of ACL injuries in the outpatient setting. So, the BLU-DAT can be a new useful tool in everyday clinical practice to assist in the diagnosis of ACL injury.

LEVEL OF EVIDENCE

II.

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.

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.

Reliability of a Novel Automatic Knee Arthrometer for Measuring Knee Laxity After Anterior Cruciate Ligament Ruptures

Background:

The accuracy of existing devices for measuring knee laxity is adversely affected by examiner reliability.

Purpose:

To compare the accuracy of a novel automatic knee arthrometer (AKA) to that of the KT-2000 arthrometer for measuring knee laxity after anterior cruciate ligament (ACL) ruptures.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

We measured anterior displacement and the anterior displacement difference (ADD) at 134 N of anterior force in 221 healthy volunteers and 200 patients with ACL ruptures. All trials were performed by the same 2 examiners. We first analyzed the effects of examiner, side assessed, and device type using the intraclass correlation coefficient (ICC), t test, and F test. We then used the receiver operating characteristic curve to compare the diagnostic value of the measurements between devices.

Results:

In repeated measurements for a single healthy volunteer, there were no differences in the variance of the measurements between sides according to the AKA (standard deviation of right vs left knee for examiner A: 0.43 vs 0.58 mm, respectively [P = .39]; for examiner B: 0.49 vs 0.77 mm, respectively [P = .81]), while the KT-2000 measurements showed differences (standard deviation of right vs left knee for examiner A: 1.47 vs 0.80 mm, respectively [P = .02]; for examiner B: 1.78 vs 0.91 mm, respectively [P = .01]). The ADD assessed by the AKA was not significantly different between examiners A and B (0.50 vs 0.75 mm, respectively; P = .27; ICC = 0.83), but the KT-2000 showed a difference (1.07 vs 2.01 mm, respectively; P = .01; ICC = 0.55). The ADD of 20 healthy volunteers assessed by the AKA was less than that by the KT-2000 (0.98 vs 1.41 mm, respectively; P = .04). When comparing the diagnostic value of the 2 devices in the sample of 200 patients with ACL ruptures and 200 healthy controls, the area under the receiver operating characteristic curve for the AKA was larger than that for the KT-2000 (0.93 vs 0.87, respectively; P ≤ .01), and the threshold values were 1.75 and 2.73 mm, respectively.

Conclusion:

The AKA can be used to determine the degree of knee laxity in ACL injuries and to provide indications for treatment.

Effect of Tibial Tunnel Placement Using the Lateral Meniscus as a Landmark on Clinical Outcomes of Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

BACKGROUND

It remains unclear if use of the lateral meniscus anterior horn (LMAH) as a landmark will produce consistent tunnel positions in the anteroposterior (AP) distance across the tibial plateau.

PURPOSE

To evaluate the AP location of anterior cruciate ligament (ACL) reconstruction tibial tunnels utilizing the LMAH as an intra-articular landmark and to examine how tunnel placement affects knee stability and clinical outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective review was conducted of 98 patients who underwent primary ACL reconstruction with quadrupled hamstring tendon autografts between March 2013 and June 2017. Patients with unilateral ACL injuries and a minimum follow-up of 2 years were included in the study. All guide pins for the tibial tunnel were placed using the posterior border of the LMAH as an intra-articular landmark. Guide pins were evaluated with the Bernard-Hertel grid in the femur and the Stäubli-Rauschning method in the tibia. Patients were divided by the radiographic location of the articular entry point of the guide pin with relation to the anterior 40% of the tibial plateau. Outcomes were evaluated by the Marx Activity Scale and International Knee Documentation Committee (IKDC) form. Anterior knee laxity was evaluated using a KT-1000 arthrometer and graded with the objective portion of the IKDC form. Rotational stability was evaluated using the pivot-shift test.

RESULTS

A total of 60 patients were available for follow-up at a mean 28.6 months. The overall percentage of AP placement of the tibial tunnel was 39.3% ± 3.8% (mean ± SD; range, 31%-47%). Side-to-side difference of anterior knee laxity was significantly lower in the anterior group than the posterior group (1.2 ± 1.1 mm vs 2.5 ± 1.3 mm; P < .001; r = 0.51). The percentage of AP placement of the tibial tunnel demonstrated a positive medium correlation with side-to-side difference of anterior knee laxity as measured by a KT-1000 arthrometer (r = 0.430; P < .001). The anterior group reported significantly better distribution of IKDC grading as compared with the posterior group (26 grade A and 6 grade B vs 15 grade A and 13 grade B; P = .043; V = 0.297). The pivot-shift test results and outcome scores showed no significant differences between the groups.

CONCLUSION

Using the posterior border of the LMAH as an intraoperative landmark yields a wide range of tibial tunnel locations along the tibial plateau, with anterior placement of the tibial tunnel leading toward improved anterior knee stability.

Anterior knee translation measurements after ACL reconstruction are influenced by the type of laximeter used

PURPOSE

Laximeters were designed to diagnose an anterior cruciate ligament (ACL) deficient knee, but their use has now focused on providing an objective assessment of the anterior translation (AT) of an intact and ACL-reconstructed knee. In this study we report the introduction and direct comparison of an automated and computerized AT measurement device, GNRB, with the device previously established by the institute and as the current literature standard, the KT1000.

METHODS

A prospective data collection was commenced upon introduction of the GNRB. The measurements of AT in each patient were performed by the same investigator with each device using 134 N applied to both knees, giving a side-to-side difference. The investigators were a sport scientist, a biomechanical engineer and a physiotherapist. Increased AT was defined as a difference > 3 mm.

RESULTS

Three investigators performed the measurements in 122 patients, 9.8 (± 1.8) months after ACL reconstruction. Mean AT of the healthy knee was 5.7 mm with KT1000 and 4.4 mm with GNRB (p = 0.002). Mean AT of the ACL reconstructed knee was 7.0 mm with the KT1000 and 5.3 mm with the GNRB (p = 0.037). The KT1000 had a higher variance of results than the GNRB (p < 0.001). There were 25 patients with increased AT measured by KT1000 compared with 12 patients using the GNRB (p < 0.016), with only 5 on both devices.

CONCLUSIONS

GNRB has better consistency of results when compared to the KT1000. Both devices lack comparability for detecting increased AT, with the KT1000 recording a side-to-side difference of more than 3 mm in twice as many patients as the GNRB.

LEVEL OF EVIDENCE

II.

[Modified arthroscopic technique to replace the posterior cruciate ligament in multiligament knee injuries : Results compared to open tibial inlay technique]

BACKGROUND

There is no standard procedure regarding surgical treatment of multiligament knee injuries involving rupture of the posterior cruciate ligament.

OBJECTIVE

Does the modified and purely arthroscopic operation technique show similarly good results compared to the familiar open tibial inlay technique?

METHODS

A total of four patients were surgically treated using the open tibial inlay technique (group A) and seven using the modified arthroscopic approach (group B). The prospectively designed follow-up examination comprised the Lysholm score, the subjective questionnaire of the International Knee Documentation Committee (IKDC) score as well as the specifically extended Orthopedic Working Group Knee (OAK) score for clinical assessment. Tests on translational movability of the knee joint were performed with the Rolimeter®. The level of statistical significance alpha was set at 5%.

RESULTS

The follow-up examination took place on average 28.5 ± 19.60 months and 30.6 ± 26.26 months postoperatively in groups A and B, respectively. Groups A and B recorded mean 70.3 ± 5.32 and 69.6 ± 19.82 points in the Lysholm score, respectively. In the subjective IKDC score group A showed 67.3 ± 7.76 points and group B 65.9 ± 12.35 points. The OAK score was 77.5 ± 6.10 points in group A and 75.3 ± 11.31 points in group B. The side difference in the posterior drawer test was 1.75 ± 1.192 mm in group A and 2.50 ± 2.160 mm in group B. In the reverse Lachman test differences of 2.37 ± 2.175 mm and 3.22 ± 2.059 mm were measured in groups A and B, respectively. All values showed no significant differences between the two evaluated groups.

CONCLUSION

The results of the two operation techniques were not significantly different. The arthroscopic approach is therefore regarded as the preferred method in this institute.

Healthy knee KT1000 measurements of anterior tibial translation have significant variation

PURPOSE

The most commonly used arthrometer for measuring and reporting anterior tibial translation after anterior cruciate ligament reconstruction is the KT1000. Reports on its consistency and reproducibility vary in the literature, but it remains the "gold standard". The purpose of this study was to assess agreement of KT1000 measurements in a daily clinical setting.

METHODS

A retrospective analysis of anterior knee translation in the healthy knee of 770 patients over a 17-year time period was performed. In this cohort, a total of 24 investigators performed 1890 measurement sets at 89 Newtons (N), 134N and at maximum manual force (MMax) level. To assess the inter- and intra-observer agreement, the intraclass-correlation coefficient (ICC) was calculated. The "investigator effect" was a difference between two examiners in the same patient and the "device effect'' a difference within one examiner in the same patient. Minimally important difference (MID) was calculated as 0.5 of the standard deviation.

RESULTS

Thirteen investigators were female, performing 1099 measurements and 11 were male, performing 791 measurements. ICC ranged between 0.558 and 0.644. At the MMax level, male investigators had a higher mm reading than female investigators (p < 0.001). Increased experience did not correlate with a higher ICC. MID ranged between 0.85 and 1.65 mm.

CONCLUSION

This study investigated the KT1000 arthrometer in a clinical setting with a large number of investigators. This device delivers moderate agreement of results. Both the device and investigator effect are present. The MMax level has shown the lowest agreement and a dependency on the investigator gender.

LEVEL OF EVIDENCE

Level III diagnostic study.

Clinical, functional, and isokinetic study of a prospective series of anterior cruciate ligament ligamentoplasty with pedicular hamstrings

PURPOSE

Few studies describe the specific results of anterior cruciate ligament reconstruction with pedicled hamstring graft (HG). Our goal was to report the isokinetic, clinical, and functional outcomes over the post-operative year following pedicled hamstring ligamentoplasty.

METHODS

Twenty-four patients with ACL rupture (mean age 27.4 years) were included prospectively. The technique used a four-stranded HG transplant pedicled to the tibia. The functional result (Lysholm knee score and subjective IKDC score), clinical result (KT-1000, Lachman test, joint amplitudes, objective IKDC score), and isokinetic complication occurrence were analyzed at six months and 12 months follow-up. The functional results, clinical parameters, and complications were analyzed at 30 months follow-up. The comparison of the variables with the various regressions was carried out by a Wilcoxon sign test.

RESULTS

Twenty-one patients were reviewed at six, nine, 12, and 30 months. The mean Lysholm knee score was 90/100 at six months, 96/100 at one year, and 95/100 at 30 months. The mean subjective IKDC score was 77/100 and 89/100 at six and 12 months, and 91/100 at 30 months. The mean difference in laxity compared with the healthy knee was 1.4 mm at six months, 1.9 mm at 12 months, and 2 mm at 30 months. The objective IKDC score was A or B for all patients at 12 and 30 months. The average quadriceps strength deficit decreased from 27 to 16% between six and 12 months post-operative (p = 0.0091) and the average flexor deficit from 23 to 12% (p = 0.0084). No complications were identified.

CONCLUSION

The abovementioned technique allows reaching functional, clinical, and isokinetic results comparable with the standard techniques while preserving the mechanical and biological interest of tibial insertion.

The unhappy triad of the knee re-revisited

AIM OF THE STUDY

To describe the surgical findings of the anterolateral complex in patients with the "unhappy triad" lesion of the knee.

METHOD

One hundred and twenty-five consecutive patients presenting with acute anterior cruciate ligament (ACL) tears were selected for this study. Only cases, evaluated with a valgus stress test under fluoroscopy, with a medial opening more than 5 mm of the medial collateral ligament (MCL) were included in the study (11 patients). For the included cases, open MCL surgical repair was performed only in cases with a valgus stress test more than 10 mm as revealed by fluoroscopy (3 patients). All included cases (11 patients) underwent ACL reconstruction and exploration of the anterolateral complex that was then assessed, photographed, classified, and eventually repaired.

RESULTS

At clinical evaluation under anaesthesia, all patients presented a positive Lachman test and a pivot shift test graded as ++ in four cases and +++ in five cases, not valuable in two cases. At surgical exploration, the anterolateral complex was involved in all cases (11 patients): one case demonstrated a type I injury, eight cases a type II injury, two cases a type III injury, and no patient with a type IV injury (Segond's fracture). All anterolateral complex lesions were repaired by direct suture and re-tensioning.

DISCUSSION

On the basis of a recent analysis performed by other authors, we could speculate that injuries of ACL and anterolateral compartment occur in the very early phase of the injury when the knee is forced into internal rotation. The MRI evidence of bone bruising in the lateral compartment in most cases of the present series support the hypothesis of an internal rotation torque.

CONCLUSIONS

The unhappy triad of injuries to the knee is actually a tetrad involving not just the ACL, MCL, and medial/lateral meniscus but also involved the anterolateral complex.