The combination of radiostereometric analysis and the telos stress device results in poor precision for knee laxity measurements after anterior cruciate ligament reconstruction

The lateral joint space width can be measured reliably with Telos valgus stress radiography in medial knee osteoarthritis

OBJECTIVE

To examine the reproducibility of valgus stress radiographs with the Telos stress device for assessment of lateral compartment degenerative changes in patients with medial osteoarthritis of the knee.

MATERIALS AND METHODS

A prospective reliability study was performed. Seventy-nine patients (80 knees) were included, and standardized valgus stress radiographs were obtained using the Telos stress device. Osteophytes and joint space narrowing (JSN) were graded using the OARSI (Osteoarthritis Research Society International) classification, and the joint space width (JSW) was measured in millimeters. Reproducibility was determined as intra-and inter-rater reliability and test-retest reliability. Weighted kappa was used to determine the reliability of osteophyte and JSN grading, and the intra-class correlation coefficient for JSW.

RESULTS

Grading of osteophytes had an intra- and inter-rater reliability ranging from 0.40 to 0.83 on the medial side and ranging from 0.39 to 0.87 on the lateral side. Grading of medial JSN had an intra- and inter-rater reliability ranging from 0.62 to 0.84, and grading of lateral JSN had an intra- and inter-rater reliability ranging from 0.32 to 0.65. Intra- and inter-rater reliability of JSW ranged from 0.84 to 0.98 on the medial side, and from 0.59 to 0.89 on the lateral side. Test-retest reliability of JSW of the medial and lateral side ranged from 0.69 to 0.92.

CONCLUSIONS

Standardized valgus stress radiographs taken with the Telos stress device are a reliable supplement in the assessment of medial OA of the knee. Evaluation of the lateral compartment on valgus stress radiographs is most reliable with measurement of the lateral JSW.

Passive anterior tibia translation in anterior cruciate ligament-injured, anterior cruciate ligament-reconstructed and healthy knees: a systematic review

Abstract

Anterior tibia translation (ATT) is mainly prevented by the anterior cruciate ligament. Passive ATT tests are commonly used to diagnose an anterior cruciate ligament (ACL) injury, to select patients for an ACL reconstruction (ACLR), and as an outcome measure after an ACLR. The aim of this review was to present an overview of possible factors determining ATT. A second purpose was to give a summary of the ATT measured in the literature in healthy, ACL-injured and ACLR knees and a comparison between those groups. A literature search was conducted with PubMed. Inclusion criteria were full-text primary studies published in English between January 2006 and October 2016. Studies included reported ATT in explicit data in healthy as well as ACL-injured or ACLR knees or in ACL-injured as well as ACLR knees. Sixty-one articles met inclusion criteria. Two articles measured the ATT in healthy as well as ACL-injured knees, 51 in ACL-injured as well as in ACLR knees, three in ACLR as well as in healthy knees and three in healthy, ACL-injured and ACLR knees. A difference in ATT is found between healthy, contralateral, ACLR and ACL-injured knees and between chronic and acute ACL injury. Graft choices and intra-articular injuries are factors which could affect the ATT. The mean ATT was lowest to highest in ACLR knees using a bone–patella tendon–bone autograft, ACLR knees using a hamstring autograft, contralateral healthy knees, healthy knees, ACLR knees with an allograft and ACL-injured knees. Factors which could affect the ATT are graft choice, ACL injury or reconstruction, intra-articular injuries and whether an ACL injury is chronic or acute. Comparison of ATT between studies should be taken with caution as a high number of different measurement methods are used. To be able to compare studies, more consistency in measuring devices used should be introduced to measuring ATT. The clinical relevance is that an autograft ACLR might give better results than an allograft ACLR as knee laxity is greater when using an allograft tendon.

Level of evidence

III.

Validity of rotational laxity coupled with anterior translation of the knee: A cadaveric study comparing radiostereometry and the Rotab®

BACKGROUND

In current practice, anterior cruciate ligament (ACL) tears can be diagnosed using several devices to measure anterior tibial translation and rotational knee laxity, but these measures are never collected together. The Rotab®, which yields simultaneous measurements of anterior tibial translation and passive lower limb rotation under stress, would therefore be advantageous in current practice, but its reliability has never been tested.

AIM OF STUDY

To evaluate the accuracy and reliability of the Rotab® compared to the reference system, radiostereometric analysis (RSA).

METHODS

This anatomical study was conducted on 14 lower limbs collected from fresh cadavers. Simultaneous measurements of anterior tibial translation and rotation were obtained with both systems, with antero-posterior (AP) forces of 134N and 250N using the Rotab®. Measurements were made on intact ACL and then repeated after ACL section. Variables were analyzed in univariate analysis by ANOVA, and the intraclass correlation coefficient (ICC) between the systems was determined by the Bland and Altman method.

RESULTS

The difference between the two methods for evaluating anterior tibial translation was 0.05±0.98mm at 134N and 0.29±1.04mm at 250N. The correlation between the tests was high (r₁₃₄=r₂₅₀=0.97, p=0.8). The difference between the two methods for rotational laxity was 0.69±2.7° at 134N and 0.5±0.6° at 250N. The Rotab® showed a significant difference only at 250N for rotational laxity after the ACL tear.

CONCLUSION

The Rotab® is a reliable device to measure rotational laxity coupled with anterior translation of the knee.

An analysis of normative data on the knee rotatory profile and the usefulness of the Rotatometer, a new instrument for measuring tibiofemoral rotation: the reliability of the knee Rotatometer

PURPOSE

This study proposes a simple and noninvasive instrument called the "Rotatometer" to measure tibiofemoral rotation and investigates its clinical applicability to the assessment of static rotational knee laxity.

METHODS

The degree of tibiofemoral rotation was measured for a sample of 94 healthy volunteers with 188 knees by using the Rotatometer. The measurement was made by two independent and blinded examiners in three sessions at one-month intervals. The normative rotational profile and its relationship with gender and age were evaluated, and inter-observer reliability and intra-observer reliability were calculated.

RESULTS

Males showed 62° ± 5° of external rotation, whereas females, 64° ± 5°. Males showed 44° ± 5° of internal rotation, whereas females, 49° ± 4°. Females showed significantly higher degrees of rotation than males. Tibiofemoral rotation was not correlated with age, and external rotation and internal rotation had a moderate positive relationship. Inter-observer reliability ranged from 0.84 to 0.91 for external rotation and 0.90 to 0.95 for internal rotation, and intra-observer reliability ranged from 0.69 to 0.89 for external rotation and 0.87 to 0.95 for internal rotation.

CONCLUSIONS

The results suggest the Rotatometer to be a simple and noninvasive device with high inter- and intra-observer reliability. The device can provide a normative rotational profile for reference purposes and thus can be used to determine the preoperative and postoperative rotational status of knees with anterior cruciate ligament injuries and compare results from different reconstruction techniques.

Rolimeter measurements are suitable as substitutes to stress radiographs in the evaluation of posterior knee laxity

PURPOSE

The quantification of posterior knee laxity is crucial in the evaluation of injuries to the posterior cruciate ligament (PCL) as it has important implications to the treatment for these injuries. The objective of this study was to compare the test results of stress radiography and instrumented drawer testing (Rolimeter) for the assessment of posterior knee laxity in patients with PCL injury.

METHODS

In 45 patients with an injury to the PCL, lateral radiographs of both knees were obtained under anterior and posterior tibial load (150 N) using a standardized approach. Patients with injury of the ACL to either knee were excluded from the study. During the same clinic visit, an instrumented measurement of anterior-posterior knee laxity was performed at 90° of knee flexion by an experienced examiner using the Rolimeter device. The mean side-to-side differences (SSD) of both (radiographic and instrumented) measurements were compared to each other, and the correlation was calculated using the Pearson coefficient.

RESULTS

The SSD (affected/healthy side) of posterior translation determined from the radiographs was 8.2 ± 3.2 mm, and the SSD of the instrumented measurement testing was 7.6 ± 3.2 mm. The mean difference between radiographic and Rolimeter test results was 1.8 ± 1.5 mm. The Pearson's correlation coefficient revealed a good correlation between both measurements of 0.74.

CONCLUSIONS

It may be suggested by the results of this study that under the absence of an ACL injury and a fixed posterior drawer sign, the Rolimeter is a suitable tool to assess the posterior laxity of the knee in the clinical setting. Its advantages are the absence of radiation to the patient, its availability, and the low cost. Therefore, the Rolimeter device may serve as a valuable alternative to stress radiography in the evaluation of PCL-injured patients.

LEVEL OF EVIDENCE

II.

Assessment of rotatory laxity in anterior cruciate ligament-deficient knees using magnetic resonance imaging with Porto-knee testing device

PURPOSE

Objective evaluation of both antero-posterior translation and rotatory laxity of the knee remains a target to be accomplished. This is true for both preoperative planning and postoperative assessment of different ACL reconstruction emerging techniques. The ideal measurement tool should be simple, accurate and reproducible, while enabling to assess both ‘‘anatomy’’ and ‘‘function’’ during the same examination. The purpose of this study is to evaluate the clinical effectiveness of a new in-house developed testing device, the so-called Porto-knee testing device (PKTD). The PKTD is aimed to be used on the evaluation of both antero-posterior and rotatory laxity of the knee during MRI exams.

METHODS

Between 2008 and 2010, 33 patients with ACLdeficient knees were enrolled for the purpose of this study. All patients were evaluated in the office and under anesthesia with Lachman test, lateral pivot-shift test and anterior drawer test. All cases were studied preoperatively with KT-1000 and MRI with PKTD, and examinations performed by independent observers blinded for clinical evaluation. During MRI, we have used a PKTD that applies antero-posterior translation and permits free tibial rotation through a standardized pressure (46.7 kPa) in the proximal posterior region of the leg. Measurements were taken for both knees and comparing side-to-side. Five patients with partial ruptures were excluded from the group of 33.

RESULTS

For the 28 remaining patients, 3 women and 25 men, with mean age of 33.4 ± 9.4 years, 13 left and 15 right knees were tested. No significant correlation was noticed for Lachman test and PKTD results (n.s.). Pivot-shift had a strong positive correlation with the difference in anterior translation registered in lateral and medial tibia plateaus of injured knees (cor. coefficient = 0.80; p\0.05), and with the difference in this parameter as compared to side-to-side (cor. coefficient = 0.83; p\0.05). Considering the KT-1000 difference between injured and healthy knees, a very strong positive correlation was found for side-to-side difference in medial (cor. coefficient = 0.73; p\0.05) and lateral (cor. coefficient = 0.5; p\0.05) tibial plateau displacement using PKTD.

CONCLUSION

The PKTD proved to be a reliable tool in assessment of antero-posterior translation (comparing with KT-1000) and rotatory laxity (compared with lateral pivotshift under anesthesia) of the ACL-deficient knee during MRI examination.

LEVEL OF EVIDENCE

Therapeutic studies, Level IV.

A new diagnostic approach using regional analysis of anterior knee laxity in patients with anterior cruciate ligament deficiency

PURPOSE

The first purpose of this study was to analyze the characteristics of the anterior knee laxity in the three regions of different stiffness in the force-displacement curve, which was obtained from a frequently used arthrometer for quantifying knee joint stability in the patients with anterior cruciate ligament (ACL) rupture and the healthy controls. The second purpose was to compare the characteristics from the regional analysis of the anterior knee laxity between the two subject groups in order to explore proper diagnosis criteria.

METHODS

Seventy-one patients with unilateral ACL tear and eighty healthy controls were enrolled and their anterior knee laxities were tested using the KT-2000 arthrometer. The displacements and stiffness of the three regions were extracted separately and compared between groups to further develop the diagnostic criteria.

RESULTS

The results indicated that the laxity behavior was mostly affected in Region 2 and Region 3 after ACL tear. Two good indicators for ACL tear were found in the receiver operating characteristic (ROC) curve analysis: Region 2 with the displacement larger than 3.7 mm and Region 3 with the stiffness smaller than 22 N/mm. These two criteria provided a better diagnostic accuracy with increased sensitivity.

CONCLUSIONS

The regional analysis method developed in this study could provide more information for understanding the characteristics of the anterior knee laxity and help increase the diagnostic accuracy for ACL rupture.

LEVEL OF EVIDENCE

II.