Objective measurement devices to assess static rotational knee laxity: focus on the Rotameter (original) (raw)
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Rotational knee laxity: reliability of a simple measurement device in vivo
BMC Musculoskeletal Disorders, 2008
Background: Double bundle ACL reconstruction has been demonstrated to decrease rotational knee laxity. However, there is no simple, commercially-available device to measure knee rotation. The investigators developed a simple, non-invasive device to measure knee rotation. In conjunction with a rigid boot to rotate the tibia and a force/moment sensor to allow precise determination of torque about the knee, a magnetic tracking system measures the axial rotation of the tibia with respect to the femur. This device has been shown to have acceptable levels of test re-test reliability to measure knee rotation in cadaveric knees.
International Scholarly Research Notices, 2015
The present paper deals with the design, the repeatability, and the comparison to literature data of a new measuring device called “Rotameter” to characterize the rotational knee laxity or the tibia-femoral rotation (TFR). The initial prototype P1 of the Rotameter is shortly introduced and then modified according to trials carried out on a prosthetic leg and on five healthy volunteers, leading therefore to an improved prototype P2. A comparison of results obtained from P1 and P2 with the same male subject shows the enhancements of P2. Intertester and intratester repeatability of this new device were shown and it was observed that rotational laxities of left and right knees are the same for a healthy subject. Moreover, a literature review showed that measurements with P2 presented lower TFR values than other noninvasive devices. The measured TFR versus torque characteristic was quite similar to other invasive devices, which are more difficult to use and harmful to the patient. Hence,...
Arthroscopy: The Journal of Arthroscopic & Related Surgery, 2011
Purpose: A test setup for clinical use in the awake and non-anesthetized patient measuring anteroposterior translation and rotation of the knee joint is the subject of validation. Methods: A measuring device featuring fixation of the foot at 30°of knee flexion with varus/valgus stress posts for the knee was developed. Tibial rotation (external/internal) was imposed with a torque of 2 Nm on the footrest with the ankle locked in dorsiflexion. Anterior translation of the tibia in relation to the femur was measured with a commercially available arthrometer. Measurements were performed in a neutral position, internal rotation, and external rotation. Intrarater and inter-rater reliability was validated in 10 healthy volunteers (Cronbach ␣). We examined 10 patients with isolated anterior cruciate ligament (ACL) rupture, as well as 10 patients with ACL rupture plus medial instability and 10 patients with additional lateral instability. Side-to-side differences were used for calculation. Results: Comparison of healthy volunteers and subjects with isolated ACL rupture showed significant differences: internal rotation, 0.79 mm and 2.46 mm, respectively (P ϭ .001); neutral position, 0.4 mm and 3.35 mm, respectively (P Ͻ .0001); and external rotation, 0.29 mm and 2.5 mm, respectively (P ϭ .003). Significant differences (P ϭ .008) were found between isolated ACL rupture and ACL rupture plus medial instability by use of the ratio of anterior translation in external rotation versus the neutral position. Inter-rater reliability was 0.948 in 10 healthy volunteers and 0.981 in 10 subjects with unilateral ACL rupture. Intrarater reliability in the volunteers was 0.829. Conclusions: By use of the developed measurement device, the "Laxitester" (ORTEMA Sport Protection, Markgroeningen, Germany), objective differentiation between isolated ACL rupture and ACL rupture plus additional medial instability is possible. Values for anterior translation are reliable and reproducible by different examiners and by the same examiner at different times. Clinical Relevance: The Laxitester allows objectification of medial instability in combination with ACL injuries and provides a reference regarding the need for additional medial stabilization. Compared with the isolated measurement of anteroposterior translation, knee instability can be assessed in a more differentiated manner.
Measurements of knee rotation-reliability of an external device in vivo
BMC Musculoskeletal Disorders, 2011
Background: Knee rotation plays an important part in knee kinematics during weight-bearing activities. An external device for measuring knee rotation (the Rottometer) has previously been evaluated for validity by simultaneous measurements of skeletal movements with Roentgen Stereometric Analysis (RSA). The aim of this study was to investigate the reliability of the device.
A new technique for measuring the rotational axis pathway of a moving knee
The Knee, 1998
The current lack of objective tests to measure the instability of a moving knee means that the effectiveness of an anterior Ž. cruciate ligament ACL reconstruction cannot be accurately determined. This article describes a new technique for measuring the rotational axis pathway of a moving knee. It shows how this can be used to detect ACL deficiency and discusses how such measurements may be used to quantify dynamic instability. The article reports the results of a pilot study on 14 patients with unilateral symptomatic ACL deficiency. Subjects had their rotational axis pathways measured in both normal and unstable knees. On comparison, the unstable knee showed a consistent difference relative to the normal knee in all cases.
Influence of individual characteristics on static rotational knee laxity using the Rotameter
Knee Surgery, Sports Traumatology, Arthroscopy, 2012
Purpose The purpose of this study was to evaluate the influence of individual characteristics on rotational knee laxity in healthy participants. Our second aim was to verify whether the contralateral knee of patients with a noncontact ACL injury presents greater rotational knee laxity than a healthy control group. Methods Sixty healthy participants and 23 patients having sustained a non-contact ACL injury were tested with a new Rotameter prototype applying torques up to 10 Nm. Multiple linear regressions were performed to investigate the influence of gender, age, height and body mass on rotational knee laxity and to establish normative references for a set of variables related to rotational knee laxity. Multiple analyses of covariance were performed to compare the contralateral knee of ACL-injured patients and healthy participants. Results Being a women was associated with a significantly (P \ 0.05) higher rotational knee laxity, and increased body mass was related to lower laxity results. In the multiple analyses of covariance, gender and body mass were also frequently associated with rotational knee laxity. When controlling for these variables, there were no differences in measurements between the contralateral leg of patients and healthy participants. Conclusion In the present setting, gender and body mass significantly influenced rotational knee laxity. Furthermore, based on these preliminary results, patients with noncontact ACL injuries do not seem to have excessive rotational knee laxity. Level of evidence Retrospective comparative study, Level III.
The accuracy of clinical examination of rotational and sagittal laxity of the knee
2020
Purpose: This study evaluates the accuracy and reliability of clinical examination for knee laxity in degrees and millimetres when compared to movement measured by computer-assisted navigation. Methods: A cadaver lower limb was connected to a computer assisted knee surgery system (CAS) and calibrated through a mini medial parapatellar arthrotomy. Examiners estimated millimetres of sagittal and degrees of rotational laxity of the knee at 30º and 90º of knee flexion. This examination was done in the ligamentous intact knee and again after sequential release of the anterior cruciate ligament (ACL) and anterolateral ligament (ALL). The clinical assessments were compared with measurements produced by CAS. Intraclass correlation coefficient (ICC), correlation coefficient (CC) and Bland Altman plots were used to compare and summarize the data. Results: At least 21 participants assessed the knee after each sequence of ligament sectioning. The reliability of clinical examination when correla...
A new knee arthrometer, the GNRB®: Experience in ACL complete and partial tears
Orthopaedics & Traumatology: Surgery & Research, 2009
Introduction.-Clinical diagnosis of anterior cruciate ligament (ACL) tears (Lachman test and Pivot shift test in valgus and internal rotation) is reliable in case of complete ACL tear but reveals elusive in case of partial tears. Quantitative assessment of anterior tibial translation proves to be imprecise, subjective and poorly reproducible especially with the KT-1000 arthrometer. We developed the GNRB ® , an alternative original anterior knee laxity measurement device. The lower limb is placed in a rigid support with the knee at 0 • of rotation, the restraining power being recorded. A 0-250 N thrust force is transmitted by a jack to the upper segment of the calf. This force is only applied in the absence of hamstring muscles contraction. Displacement of the anterior tibial tubercle is recorded using a sensor with a 0.1 mm precision. Hypothesis.-We hypothesize that this knee laxity measurement device is more reliable and reproducible than other currently available arthrometers. Material and methods.-During a first validation study, the GNRB ® was compared to the KT-1000 arthrometer, in 20 pairs of healthy knees, measurements being performed by two investigators. Variance analyses were carried out at 134 N. In a second clinical study, 21 complete ACL tears (the notch is devoid of ACL) and 24 partial ACL tears (anterior or posterior bundle tear and cicatricial ACL remnant in continuity) were tested with these arthrometers to exact a differential laxity threshold value between both knees at 250 N. Statistical analysis was subsequently performed using variance and ROC curves analysis.
International Scholarly Research Notices, 2015
The purpose of this study is to validate a noninvasive rotational knee laxity measuring device called “Rotameter P2” with an approach based on Computed Tomography (CT). This CT-approach using X-rays is hence invasive and can be regarded as a precise reference method that may also be applied to similar devices. An error due to imperfect femur fixation was observed but can be neglected for small torques. The most significant estimation error is due to the unavoidable soft tissues rotation and hence flexibility in the measurement chain. The error increases with the applied torque. The assessment showed that the rotational knee angle measured with the Rotameter is still overestimated because of thigh and femur displacement, soft tissues deformation, and measurement artefacts adding up to a maximum of 285% error at +15 Nm for the Internal Rotation of female volunteers. This may be questioned if such noninvasive devices for measuring the Tibia-Femoral Rotation (TFR) can help diagnosing kn...
Static rotational knee laxity in anterior cruciate ligament injuries
Knee Surgery, Sports Traumatology, Arthroscopy, 2012
Purpose The purpose was to provide an overview of the non-invasive devices measuring static rotational knee laxity in order to formulate recommendations for the future. Results Early cadaver studies provided evidence that sectioning the anterior cruciate ligament (ACL) led to an increase of static rotational knee laxity of approximately 10-20% between full extension and 30°of knee flexion. Sections of the menisci or of the peripheral structures induced a much higher increase in rotation. This supported the hypothesis that static rotation measurements might be useful for the diagnosis of ACL or associated injuries. In vivo evaluations with measurement devices are relatively new. Several articles were published during the last decade with many different devices and important differences were seen in absolute rotational knee laxity between them. This was due to the varying precision of the devices, the variability in patient positioning, the different methods of measurement, examination protocols and data analysis. As a consequence, comparison of the available results should be performed with caution. Nevertheless, it has been established that rotational knee laxity was greater in females as compared to males and that the inter-subject variability was high. For this reason, it will probably be difficult to categorise injured patients preoperatively, and the interpretation of the results should probably be limited to side-to-side differences. Conclusion Future studies will show whether rotational laxity measurements alone will be sufficient to provide clinically relevant data or if they should be combined to static sagittal laxity measurements.