A new device for patellofemoral instrumented stress-testing provides good reliability and validity

Inconsistency in Shoulder Arthrometers for Measuring Glenohumeral Joint Laxity: A Systematic Review

There is no consensus on how to measure shoulder joint laxity and results reported in the literature are not well systematized for the available shoulder arthrometer devices. This systematic review aims to summarize the results of currently available shoulder arthrometers for measuring glenohumeral laxity in individuals with healthy or injured shoulders. Searches were conducted on the PubMed, EMBASE, and Web of Science databases to identify studies that measure glenohumeral laxity with arthrometer-assisted assessment. The mean and standard deviations of the laxity measurement from each study were compared based on the type of population and arthrometer used. Data were organized according to the testing characteristics. A total of 23 studies were included and comprised 1162 shoulders. Populations were divided into 401 healthy individuals, 278 athletes with asymptomatic shoulder, and 134 individuals with symptomatic shoulder. Sensors were the most used method for measuring glenohumeral laxity and stiffness. Most arthrometers applied an external force to the humeral head or superior humerus by a manual-assisted mechanism. Glenohumeral laxity and stiffness were mostly assessed in the sagittal plane. There is substantial heterogeneity in glenohumeral laxity values that is mostly related to the arthrometer used and the testing conditions. This variability can lead to inconsistent results and influence the diagnosis and treatment decision-making.

Utility of Diagnostic Ultrasound in the Assessment of Patellar Instability

Background

The use of imaging to diagnose patellofemoral instability is often limited by the inability to dynamically load the joint during assessment. Therefore, the diagnosis is typically based on physical examination using the glide test to assess and quantify lateral patellar translation. However, precise quantification with this technique remains difficult.

Purpose

To quantify patellar position using ultrasound imaging under dynamic loading conditions to distinguish between knees with and without medial patellofemoral complex (MPFC) injury.

Study Design

Controlled laboratory study.

Methods

In 10 cadaveric knees, the medial patellofemoral distance was measured to quantify patellar position from 0° to 40° of knee flexion at 10° increments. Knees were evaluated at each flexion angle under unloaded conditions and with 20 N of laterally directed force on the patella to mimic the glide test. Patellar position measurements were made on ultrasound images obtained before and after MPFC transection and compared for significant differences. To determine the ability of medial patellofemoral measurements to differentiate between MPFC-intact and MPFC-deficient states, area under the receiver operating characteristic (ROC) curve analysis and the Delong test were used. The optimal cutoff value to distinguish between the deficient and intact states was determined using the Youden J statistic.

Results

A significant increase in medial patellofemoral distance was observed in the MPFC-deficient state as compared with the intact state at all flexion angles (P = .005 to P < .001). When compared with the intact state, MPFC deficiency increased medial patellofemoral distance by 32.8% (6 mm) at 20° of knee flexion under 20-N load. Based on ROC analysis and the J statistic, the optimal threshold for identifying MPFC injury was 19.2 mm of medial patellofemoral distance at 20° of flexion under dynamic loading conditions (area under the ROC curve = 0.93, sensitivity = 77.8%, specificity = 100%, accuracy = 88.9%).

Conclusion

Using dynamic ultrasound assessment, we found that medial patellofemoral distance significantly increases with disruption of the MPFC.

Clinical Relevance

Dynamic ultrasound measurements can be used to accurately detect the presence of complete MPFC injury.

Development of a medical device compatible with MRI/CT to measure ankle joint laxity: the Porto Ankle Testing Device

Ankle sprains are common and often develop into chronic ankle instability. Ankle laxity is usually assessed by manual testing followed by magnetic resonance imaging to confirm the diagnosis. Manual testing however provides a subjective measure and is limited to the assessor sensibility. Current available technologies incorporate arthrometers to objectively measuring ankle laxity, but are not capable to assess the structural integrity of the capsuloligamentous structures. To overcome these limitations, we developed a novel medical device to assist in the diagnosis of ankle ligament injuries—the Porto Ankle Testing Device. With this device, it is possible to combine and correlate the assessment of the capsuloligamentous’ structural integrity with the joint functional competence (ie, joint multiplanar laxity). The main purpose of this work is to present the fundamental aspects and step-by-step development of the Porto Ankle Testing Device. We discuss the design specifications and technical requirements with the purpose to design and develop this medical device, described the features of the different components and explained the mechanical systems that are incorporated emulate manual testing and to measure the multiplanar ankle laxity. The preliminary findings are presented with the purpose to display the assessment protocol, the method of laxity measurement and the obtained results. We propose a unique and reliable medical device to safety and effectively assess ankle ligament injuries and contribute to enhance diagnosis, refine treatment indications and allow objective measurement of ligament laxity before and/or after stabilization surgery.

Unilateral anterior knee pain is associated with increased patellar lateral position after stressed lateral translation

PURPOSE

To objectively compare side-to-side patellar position and mobility in patients with idiopathic unilateral anterior knee pain (AKP) using a stress-testing device concomitantly with magnetic resonance imaging. It is hypothesized that the painful knees present greater patellar mobility than the contralateral non-painful knees.

METHODS

From a total sample of 359 patients, 23 patients with idiopathic unilateral AKP (30.9 years, 23.4 kg/m², 43% males) were included within the present study. Both knees of all the patients were examined by conventional imaging, including the measurement of trochlear sulcus angle, Caton-Deschamps index, tibial tuberosity to trochlear groove distance, patellar tilt angle and patellar subluxation (both at rest and upon quadriceps contraction). Additionally, the same patients underwent stress testing (Porto Patella Testing Device); these measurements were taken with the patella at rest, after lateral patellar translation and after lateral patellar tilt. Clinical and functional outcomes were obtained using physical examination and the Kujala and Lysholm scores.

RESULTS

Painful knees showed statistically significant higher patellar lateral position after stressed lateral translation than non-painful knees (p = 0.028), 9.8 ± 3.6 mm and 7.1 ± 6.3 mm, respectively. The adjusted multivariate logistic model identified the patellar position after lateral displacement to be significantly associated with AKP (OR = 1.165) and the model (AUC = 0.807, p < 0.001) showed reasonable sensitivity (67%) and specificity (73%).

CONCLUSION

Patients with idiopathic unilateral AKP with morphologically equivalent knees showed statistically significant increased patellar lateral position after stressed lateral displacement in their painful knee. The greater lateral patellar mobility quantified by the PPTD testing brings more objectivity to the diagnosis.

LEVEL OF EVIDENCE

II.