Rotatory knee laxity

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.

Batch Fabrication of a Polydimethylsiloxane Based Stretchable Capacitive Strain Gauge Sensor for Orthopedics

Polymer-based capacitive strain gauges are a novel and promising concept for measuring large displacements and strains in various applications. These novel sensors allow for high strain, well above the maximum values achieved with state-of-the-art strain gauges (Typ. 1%). In recent years, a lot of interest in this technology has existed in orthopedics, where the sensors have been used to measure knee laxity caused by a tear of the anterior cruciate ligament (ACL), and for other ligament injuries. The validation of this technology in the field has a very low level of maturity, as no fast, reproducible, and reliable manufacturing process which allows mass production of sensors with low cost exists. For this reason, in this paper, a new approach for the fabrication of polymer-based capacitive strain gauges is proposed, using polydimethylsiloxane (PDMS) as base material. It allows (1) the fast manufacturing of sensor batches with reproducible geometry, (2) includes a fabrication step for embedding rigid electrical contacts on the sensors, and (3) is designed to produce sensor batches in which the size, the number, and the position of the sensors can be adapted to the patient’s anatomy. In the paper, the process repeatability and the robustness of the design are successfully proven. After 1000 large-strain elongation cycles, in the form of accelerated testing caused much higher strains than in the above-mentioned clinical scenario, the sensor’s electrical contacts remained in place and the functionalities were unaltered. Moreover, the prototype of a patient customizable patch, embedding multiple sensors, was produced.

Correlation between quantitative pivot shift and generalized joint laxity: a prospective multicenter study of ACL ruptures

PURPOSE

To investigate whether an increased magnitude of quantitative rotatory knee laxity is associated with a greater level of generalized joint laxity in ACL-injured and contralateral knees.

METHODS

A total of 103 patients were enrolled across four international centers to undergo anatomic ACL reconstruction. Rotatory knee laxity was evaluated preoperatively, both in the awake state and under anesthesia, using the standardized pivot shift test. Two devices were used to quantify rotatory knee laxity; an inertial sensor, measuring the joint acceleration, and an image analysis system, measuring the lateral compartment translation of the tibia. The presence of generalized joint laxity was determined using the Beighton Hypermobility Score. The correlation between the level of generalized joint laxity and the magnitude of rotatory knee laxity was calculated for both the involved knee and the non-involved knee. Further, patients were dichotomized into low (0-4) or high (5-9) Beighton Score groups. Alpha was set at < 0.05.

RESULTS

Ninety-six patients had complete datasets, 83 and 13 in the low and high Beighton Score groups respectively. In anesthetized patients, there was a significant correlation between the degree of Beighton Score and quantitative pivot shift when analyzing the non-involved knee using the image analysis system (r = 0.235, p < 0.05). When analyzing the same knee, multivariate analysis adjusted for meniscal injury, age and gender revealed an increased odds ratio for patients with increased lateral compartment translation to be part of the high Beighton Score group (OR 1.86, 95% CI 1.10-3.17, p < 0.05). No other correlation was significant. When analyzing the dichotomized subgroups, no significant correlations could be established.

CONCLUSION

The findings in this study suggest that there is a weak correlation between generalized joint laxity and the contralateral healthy knee, indicating increased rotatory knee laxity in these patients. Generalized joint laxity does not appear to correlate with rotatory knee laxity in ACL-injured knees.

LEVEL OF EVIDENCE

Prospective cohort study; level of evidence, 2.

Analysis of the influence of anaesthesia on the clinical and quantitative assessment of the pivot shift: a multicenter international study

PURPOSE

The main goal of this work was to evaluate the pivot shift test in awake and anesthetized patients by using two different quantitative methodologies and comparing the results with the standard clinical grading, taking advantage of a multicenter international study.

METHODS

Patients between 16 and 50 years of age undergoing primary unilateral single-bundle anterior cruciate ligament (ACL) reconstruction were considered eligible. The pivot shift test was performed pre-operatively, with the patient awake and again with the patient under general anaesthesia. The pivot shift test was clinically graded as defined by the International Knee Documentation Committee. The instrumented assessment was performed by using two non-invasive acquisition systems; specifically, a system exploiting an inertial sensor and a video-based application developed on a commercial tablet using skin markers. Lateral compartment translation and the tibial acceleration reached during joint reduction were used as quantitative parameters.

RESULTS

A total of 103 patients were enrolled in the study. Statistically significant difference was found between the distributions of clinical grade evaluated in awake patients and those under general anaesthesia (P < 0.01). Comparing awake patients to those under general anaesthesia, lower values were found both for tibial acceleration (3.7 ± 1.5 vs 6.0 ± 4.6 m/s², P < 0.01) and lateral compartment translation of the involved limb (2.2 ± 1.7 vs 3.0 ± 2.2 mm, P < 0.01).

CONCLUSIONS

This study indicated that significant differences in the grading of the pivot shift test exist between awake and anesthetized patients, regardless of the use of quantitative instruments during the evaluation. Actual clinical assessment reported indeed its weakness, presenting subjective variability and dependence on tester's experience. However, several factors might influence the validity of awake examination such as experience level of examiner and cultural factors, as seen in this international multicenter study.

LEVEL OF EVIDENCE

Prospective comparative study, Level II.

Pediatric musculoskeletal injuries: role of ultrasound and magnetic resonance imaging

Pediatric musculoskeletal system is particularly prone to traumatic and sports-related injuries, both acute and chronic, i.e., overuse injuries, because of inherent conditions of weakness, such as the open physis, representing the weakest aspect within the bone, the ligamentous supports and changing biomechanics. Being aware that a quick diagnosis is essential to preserve the good functionality of the limb involved, it is mandatory for the radiologist to recognize the most common patterns of these injuries, identifying those requiring a prompt surgery, as well as be confident with the technique performed, and be supported by an important background experience and knowledge skills.

Systemic Review of Anatomic Single- Versus Double-Bundle Anterior Cruciate Ligament Reconstruction: Does Femoral Tunnel Drilling Technique Matter?

PURPOSE

To provide an up-to-date assessment of the difference between anatomic double-bundle anterior cruciate ligament (ACL) reconstruction (DB-ACLR) and anatomic single-bundle ACL reconstruction (SB-ACLR). We hypothesized that anatomic SB-ACLR using independent femoral drilling technique would be able to achieve kinematic stability as with anatomic DB-ACLR.

METHODS

A comprehensive Internet search was performed to identify all therapeutic trials of anatomic DB-ACLR versus anatomic SB-ACLR. Only clinical studies of Level I and II evidence were included. The comparative outcomes were instrument-measured anterior laxity, Lachman test, pivot shift, clinical outcomes including objective/subjective International Knee Documentation Committee (IKDC) score, Lysholm score, Tegner activity scale and complication rates of extension/flexion deficits, graft failure, and early osteoarthritis. Subgroup analyses were performed for femoral tunnel drilling techniques including independent drilling and transtibial (TT) drilling.

RESULTS

Twenty-two clinical trials of 2,261 anatomically ACL-reconstructed patients were included in the meta-analysis. Via TT drilling technique, anatomic DB-ACLR led to improved instrument-measured anterior laxity with a standard mean difference (SMD) of -0.42 (95% confidence interval [CI] = -0.81 to -0.02), less rotational instability measured by pivot shift (SMD = 2.76, 95% CI = 1.24 to 6.16), and higher objective IKDC score with odds ratio (OR) of 2.28 (95% CI = 1.19 to 4.36). Via independent drilling technique, anatomic DB-ACLR yielded better pivot shift (SMD = 2.04, 95% CI = 1.36 to 3.05). Anatomic DB-ACLR also revealed statistical significance in subjective IKDC score compared with anatomic SB-ACLR (SMD = 0.27, 95% CI = 0.05 to 0.49).

CONCLUSIONS

Anatomic DB-ACLR showed better anterior and rotational stability and higher objective IKDC score than anatomic SB-ACLR via TT drilling technique. Via independent drilling technique, however, anatomic DB-ACLR only showed superiority of rotational stability. All clinical function outcomes except subjective IKDC score were not significantly different between anatomic DB-ACLR and SB-ACLR.

LEVEL OF EVIDENCE

Level II, meta-analysis of Level I and II studies.

Rotational Knee Laxity in Anterior Cruciate Ligament Deficiency: An Additional Secondary Sign on MRI

OBJECTIVE

The objective of this study was to evaluate the accuracy of tibial rotation measurement as a secondary sign for diagnosing anterior cruciate ligament (ACL) tears with the use of MRI.

MATERIALS AND METHODS

A total of 893 MRI studies were retrospectively reviewed, and 239 patients were identified as having either an intact ACL (group 1; n = 182), an arthroscopically confirmed acutely torn ACL (group 2; n = 22), or a chronically torn ACL (group 3; n = 35). Tibial rotation was estimated by measuring the femorotibial angle (FTA).

RESULTS

The mean (± SD) FTA was significantly higher in group 2 (10.7° ± 4.8°) and group 3 (11° ± 5.5°) than in group 1 (3.2° ± 3.3°) (p < 0.001, for all cases). An FTA of 4.9° was the optimal threshold (sensitivity, 93%; specificity, 80%) for separating completely torn ACLs from intact ACLs. An FTA ranging from 4.9° to 5.5° (sensitivity, 95%; specificity, 80%) indicated a complete acute ACL tear, whereas an FTA of 5.6° or greater (sensitivity, 91.4%; specificity, 83.5%) suggested a complete chronic ACL tear.

CONCLUSION

An increased FTA indicates alteration in the femorotibial anatomic relationship and could be of value in assessing ACL tears in patients with equivocal signs on MRI.

Single- vs. double-bundle anterior cruciate ligament reconstruction: a new aspect of knee assessment during activities involving dynamic knee rotation

Few studies have compared single-bundle (SB) and double-bundle (DB) anterior cruciate ligament reconstruction (ACLR) in the knee joint during activities involving change-of-direction maneuvers and knee rotation. This study examined whether the type of ACLR contributes to postphysiotherapy outcomes, with an emphasis on knee function assessment during activities involving dynamic knee rotation. Fifteen male patients after SB ACLR and 15 male patients after DB ACLR took part in the same physiotherapy program. Twenty-four weeks after ACLR, both groups underwent anterior laxity measurement, pivot shift tests, range of movement and joint circumference measurements, subjective assessment of pain and stability levels in the knee joint, peak torque measurement of the muscles rotating the tibia toward the femur, and a run test with maximal speed and change-of-direction maneuvers. Comparative analysis did not show any differences between the results of anterior tibial translation, pivot shift test, range of movement and joint circumference, and subjective assessment of pain and knee joint stability levels. No differences were noted between the groups in peak torque values obtained from the muscles responsible for internal and external tibial rotation or results of the run test. The data obtained from this study can be used by research teams to monitor and compare the effectiveness of various study protocols involving surgical and physiotherapy treatment. The data are especially useful when combined with the clinical assessment of patients who would like to return to sport.

A two- and five-year follow-up of clinical outcome after ACL reconstruction using BPTB or hamstring tendon grafts: a prospective intervention outcome study

PURPOSE

The aim of the present study was to evaluate and compare objective and subjective outcome in patients 2 and 5 years after anterior cruciate ligament (ACL) reconstruction with either bone-patellar tendon-bone (BPTB) or hamstring grafts. The second aim was to report the prevalence of re- and contralateral ACL ruptures.

METHODS

Sixty-eight patients (BPTB, n = 34 and hamstring graft, n = 34) were evaluated preoperatively, 2 and 5 years after ACL reconstruction. Anterior knee laxity and rotational knee joint stability, muscle torque, hop length, anterior knee pain, activity level and self-reported knee function and quality of life were evaluated within and between groups. The prevalence of re- and contralateral ACL ruptures was also recorded.

RESULTS

No significant difference in anterior knee laxity, rotational knee joint stability, hop length anterior knee pain or knee function and quality of life were noted at the 5-year follow-up. No significant differences in concentric or eccentric quadriceps torque at 90°/s and 230°/s were found at any of the follow-ups between and within grafts. A significant group difference in hamstring torque 1.05 (0.02) for BPTB and 0.89 (0.02) for hamstring grafts, and in hop length (leg symmetry index) follow-up 0.94 (0.07) for BPTB compared to 0.99 (0.07) for hamstring grafts (P = 0.002) was found at the 2 year follow-up in favour of the BPTB graft, but not at the 5 year follow-up. A significant improvement over time, irrespective of graft, was found in the KOOS's subscales Sport/Rec and quality of life (P < 0.001). None of the patients, irrespective of group, returned to their pre-injury level of sport (P < 0.05). Over the five postoperative years, one man and eight women (13 %) (hamstring graft, n = 5 and BPTB graft, n = 4), sustained a total of 11 (16.2 %) new ACL ruptures: seven (10.2 %) re-ruptures and four (5.9 %) ruptures of the contralateral ACL.

CONCLUSIONS

At the 5-year follow-up, there were no significant differences in terms of anterior knee laxity, rotational knee joint stability, muscle torque, anterior knee pain, hop performance, quality of life or activity level between patients who had undergone reconstruction with BPTB or hamstring grafts. None of the patients, irrespective of group, had returned to their pre-injury level of activity. Eight out of the nine patients who had sustained a second ACL rupture were women.

Can rotatory knee laxity be predicted in isolated anterior cruciate ligament surgery?

PURPOSE

Despite the overall success of the surgical anterior cruciate ligament (ACL) reconstruction, some patients still present with instability symptoms even after the surgery, mainly due to the presence of associated lesions. At present, the pivot shift test has been reported to be the benchmark to assess rotatory knee laxity. The purpose of this study was to quantitatively evaluate rotatory knee laxity at time-zero in order to determine whether detected post-reconstruction laxity was predictable by its value measured before the reconstruction, which was hypothized to be influenced by the presence of associated lesions.

METHODS

Rotatory knee laxity was retrospectively analysed in 42 patients, including two different ACL reconstructions. The maximal anterior displacement and the absolute value of the posterior acceleration reached during the reduction of the tibial lateral compartment were intra-operatively acquired by using a navigation system and identified as discriminating parameters. For each parameter, statistical linear regression analysis (line slope and intercept) was performed between pre- and post-reconstruction values.

RESULTS

No statistically significant influence of the initial posterior acceleration on the post-reconstruction outcome was found (line slope, p > 0.05), although a statistically significant line intercept was indeed identified (p < 0.001). A statistically significant influence on the surgery outcome was instead found for the initial value of the anterior tibial displacement (line slope = 0.39, p = 0.004), meaning that, on average, about 40 % of the post-reconstruction lateral compartment displacement could be explained by the corresponding pre-reconstruction value. Both of these findings highlighted the importance of intra-operative quantification of rotatory knee laxity to identify correct indications for the surgery.

CONCLUSIONS

This study provided important implications for the future possibility of defining a quantifying tool able to assess rotatory knee laxity during ACL reconstruction. This could allow detection of additional injuries to secondary restraints by easily performing rotatory knee laxity tests, which in turn could reduce post-surgical recurrence of knee instability.