The Key Pinch Stress Radiograph to Evaluate Dorsal Subluxation in the Basilar Thumb Joint

The basilar thumb joint is the joint second most commonly affected by osteoarthritis (OA) in the hand. Evaluation of dorsal subluxation of the thumb during a functional task such as key pinch could help assess OA risk. The objectives of this study were to determine the best imaging angle for measuring thumb dorsal subluxation during key pinch and to compare subluxation to corresponding OA grades on the Eaton-Glickel, Outerbridge, and ICRS scales. Eleven cadavers cadveric forearm specimens were rigged to simulate key pinch. A mobile c-arm captured AP view images of the hand, and rotating in 5° increments toward the ulnar aspect of the arm up to 60°. Dorsal subluxation was measured on each image and compared to determine which angle captured maximum subluxation. The resulting best imaging angle was used for comparisons between dorsal subluxation of the thumb and OA grades for the basilar thumb joint. The max subluxation was in the AP view for most specimens. There was a significant correlation between subluxation and the Eaton-Glickel grade (p=0.003, R2 = 0.779), but not with either Outerbridge grades (p=0.8018) or ICRS grades (p=0.7001). Dorsal Our results indicate that dorsal thumb subluxation during key pinch should be measured in the A-P view of the forearm/handhand view. Dorsal thumb subluxation during key pinch had a significant correlation with the Eaton-Glickel radiographic measure of OA but not with more accurate visual classifications of OA.

Analysis of a Laxity Index Database and Comparison with the Fédération Cynologique Internationale Grades of This Population

Objective This study aimed to analyse the distribution of the laxity indices (LI) in a dog population, to compare the LI with the Fédération Cynologique Internationale (FCI) grades and to search for differences of LI between breeds. Study Design The database was composed of all dogs presented to the University Hospital of the Faculty of Veterinary Medicine in Ghent for obligatory hip screening between January 2016 and February 2019, and all patients presented to orthopaedic consultation between January 2017 and January 2019 for a complaint of hindlimb lameness, which underwent both a standard extended ventrodorsal radiograph of the hips and a stress radiograph revealing hip joint laxity. The latter was obtained by means of the Vezzoni-modified Badertscher distension device and the LI was calculated. For each dog of the population, the LI was then compared with the FCI grade. Results The LI values ranged between 0.15 and 1.04, with a mean of 0.46. The LI and the FCI grade increased together, and showed a moderate-to-good correlation. There was a highly significant overall difference in the mean value of LI per FCI grade group (p < 0.001). The mean LI of the Labrador Retrievers was slightly but significantly lower than the mean LI of the Golden Retrievers (p < 0.01). Conclusion The LI calculated on a stress radiograph taken with the Vezzoni-modified Badertscher distension device shows a good correlation with the FCI grade assigned on a standard extended ventrodorsal projection. A wide range of passive hip joint laxity exists in dogs considered to be phenotypically normal based on the FCI grading method.

A Retrospective Comparison of MRI and Manual Inversion Stress Radiograph Studies in the Diagnosis of Chronic Lateral Ankle Instability

Category: Ankle, Sports Introduction/Purpose: Chronic lateral ankle instability (LAI) is a common cause of ankle pain. Surgical interventions have been shown to be highly effective in alleviating patient’s symptoms once conservative care has failed. Stress radiographs have not demonstrated a clear efficacy in diagnosing ankle instability. Currently, MRI is considered to be superior to stress radiographs in the available literature. Unfortunately, the literature comparing these methods is limited. The purpose of this study is to compare the results of an MRI and manual inversion stress radiographs, in order to assess the accuracy of each modality in assessing the lateral ankle ligament competence. We believe that stress radiographs may have more value in confirming chronic ankle instability than the more expensive MRI imaging. Methods: A retrospective chart review was performed between January 2016 - July 2018 for patients diagnosed with LAI. The review identified 318 cases, of which 57 met the study criteria of having both an AP manual inversion stress radiographs, assessed by the senior author, and MRI, interpreted by a musculoskeletal radiologist, occurring within 6 months of each other without an acute injury within 12 weeks of the first image. For the remaining 57 cases, the imaging was reviewed in the following manner. For the MRI studies, the report was read from the radiologist assessing the lateral ankle complex. A positive MRI was denoted as pathology being reported by the radiologist. For the manual inversion stress radiograph, measurements were made to assess the degree of talar tilt while being stressed. A positive stress radiograph was identified based on asymmetry of the ankle joint during the stress. Results: The average time between imaging studies was 7.2±7.4 weeks (range 0.5-24 weeks). Of the 57 cases that qualified for the study, 43 (75%) had a positive stress radiograph, and 21(37%) had a positive MRI. 24 cases (42%) demonstrated a positive stress radiograph with a negative MRI, while 2 cases (4%) demonstrated a negative stress radiograph with a positive MRI. In respect to talar tilt, those patients identified as having a positive stress radiograph also had a higher average talar tilt when compared to those who did not. The degree of talar tilt for each set of criteria is summarized in Table 1. Conclusion: Historically, lateral ankle instability has been a clinical diagnosis. When further imaging is needed, our data suggests stress radiographs may demonstrate a higher reliability than MRI when assessing the competence of the lateral ankle ligaments. Asymmetry in a joint during an inversion stress examination has been shown to be indicative of multi ligament involvement. Few studies have attempted to define a talar tilt consistent with instability and our data does not meet those numbers. However, with the addition of bundled care and rising health care costs, we believe this provides a potential alternative in confirming a diagnosis of ankle instability.

Joint space widening may be a paradoxical pathologic feature of early ankle arthritis

Category: Ankle, Ankle Arthritis Introduction/Purpose: Joint space narrowing and bony spur are typical pathologic feature of early ankle osteoarthritis. The meaning of joint space widening has never been discussed in previous literature. However, we found some osteoarthritic ankles which showed joint widening with diffuse spur change.(Fig.1) We hypothesized that joint space widening may be caused by malpositioning of the talus which may lead to degenerative arthritis. The purpose of this study were to investigate the radiological abnormalities in ankles with joint space widening. Methods: In order to define joint space widening and anterior subluxation of the talus, we included 72 ankles (66 people) with no abnormalities on plain radiographs into control group. We measured joint space and lateral talar station(LTS) on plain weight- bearing radiographs.(Fig.2) The 95% prediction interval of joint space (2.4 mm to 4.2 mm) and the LTS (-0.9 mm to 3.8 mm) in the control group were regarded as a normal range. The joint space widening was defined when the joint space was wider than 4.2 mm, and the anterior subluxation of talus was defined when the LTS was larger than 3.8 mm. Thirty-two ankles (29 people) with the joint space widening which underwent operation in our clinic between 2009 and 2014 were included in patient group. Ankle instability was determined on stress radiographs (Fig.2). In the patient group, we investigated the anterior subluxation of talus and the ankle instability, and the sites of spur in conventional CT. Results: The average age was 26 years (range:18 - 35) in the control group and 33 years (range:16 - 71) in the patient group. The mean joint space of the patient group was 4.7 mm (range: 4.3 mm to 6.0 mm). In the patient group, the LTS showed a mean of 6.4 mm (range 3.9 mm -10.7 mm). Because all the LTS in the patient group was over the 3.8 mm, the anterior subluxation of talus was showed in all ankles of the patient group. In the patient group, 31 ankles (97%) showed instability on anterior stress radiograph and 24 ankles (75%) showed instability on varus stress radiograph. All ankles in the patient group showed spurs on 4 sides of ankle, anterior, posterior, medial and lateral side. Conclusion: This study showed that paradoxical joint space widening may be a pathologic feature of early ankle arthritis which had diffuse spur change, anterior displacement of the talus and ankle instability.