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BACKGROUND: Meniscus root tear is an uncommon but detrimental injury of the knee. Hoop stress is lost during meniscus root tear, which can lead to excessive tibiofemoral contact pressure and early development of osteoarthritis. Posterolateral meniscus root tears (PLRT) are more commonly associated with anterior cruciate ligament (ACL) tears. As the lateral compartment is less congruent than the medial compartment, it is more susceptible to a shearing force, which is increased in the ACL-deficient knee. In accordance with the compressive axial load, the increase in the tibial slope would generate a greater shearing force. The additional lateral compartment mobility caused by ACL tear should be reduced after ACL reconstruction (ACLR). However, there is a lack of evidence to conclude that ACLR can sufficiently limit the effect of large tibial slope (LTS) on the healing after PLRT repair. This study aimed to evaluate whether a steep LTS would be a risk factor for poorer clinical outcomes after PLRT repair concomitant with ACLR. METHODS: In this retrospective study, a chart review was conducted to identify patients with concomitant unilateral primary ACLR and PLRT repair. Patients with a partial tear or healed tear were excluded. Postoperative MRI and clinical assessments were performed at a mean follow up of 35 months. MRI data was used to measure the LTS, medial tibial slope (MTS), coronal tibial slope (CTS), the lateral-to-medial slope difference (LTS-MTS) and meniscus healing and extrusion. Functional outcomes were evaluated by patient-reported outcomes (International Knee Documentation Committee [IKDC], Lysholm and Tegner scores) and KT-1000 arthrometer assessment. Interobserver reproducibility was assessed by two reviewers. RESULTS: Twenty-five patients were identified for the analysis. Patients with larger LTS and larger LTS-MTS differences were shown to be correlated with poorer IKDC scores after surgery (R = -0.472, p = 0.017 and R = -0.429, p = 0.032, respectively). Herein, patients with LTS ≥ 6° or LTS-MTS ≥ 3° demonstrated poorer IKDC scores. CONCLUSION: A large LTS (≥ 6°) and a large difference of LTS-MTS (≥ 3°) were shown to be risk factors for poorer functional and radiological outcomes for PLRT repair in patients after ACLR. Clinically, closer monitoring and a more stringent rehabilitation plan for patients with LTS ≥ 6° or LTS-MTS ≥ 3° would be recommended.

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OBJECTIVE: To investigate changes in the median nerve, retinaculum, and carpal tunnel on ultrasound after successful endoscopic carpal tunnel release (ECTR). MATERIALS AND METHODS: This prospective study involved 37 wrists in 35 patients (5 male, 30 female; mean age ± standard deviation [SD], 56.9 ± 6.7 years) with primary carpal tunnel syndrome (CTS). An in-house developed scoring system (0-3) was used to gauge the clinical improvement after ECTR. Ultrasound was performed before ECTR, and at 1, 3, and 12 months post-ECTR. Changes in the median nerve, flexor retinaculum, and carpal tunnel morphology on ultrasound after ECTR were analyzed. Ultrasound parameters for different clinical improvement groups were compared. RESULTS: All patients improved clinically after ECTR. The average clinical improvement score ± SD at 12 months post-ECTR was 2.2 ± 0.7. The median nerve cross-sectional area proximal and distal to the tunnel decreased at all time intervals post-ECTR but remained swollen compared to normal values. Serial changes in the median nerve caliber and retinacular bowing after ECTR were more pronounced at the tunnel outlet than at the tunnel inlet. The flexor retinaculum had reformed in 25 (68%) of 37 wrists after 12 months. CONCLUSION: Postoperative changes in median nerve and retinaculum parameters were most pronounced at the tunnel outlet. Even in patients with clinical improvement after ECTR, nearly all ultrasound parameters remain abnormal at one year post-ECTR. These ultrasound parameters should not necessarily be relied upon to diagnose persistent CTS after ECTR.

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OBJECTIVE. The purpose of this study was to study changes in the median nerve, retinaculum, and carpal tunnel on MRI after successful endoscopic carpal tunnel release (ECTR). SUBJECTS AND METHODS. In this prospective study, 35 wrists in 32 patients (five men, 27 women; mean age, 56.7 ± 6.8 [SD] years) with nerve conduction test-confirmed primary carpal tunnel syndrome were evaluated from May 2013 to September 2016. Clinical scores ranging from 0 to 4 (no improvement to symptoms completely resolved) and MRI morphologic features of median nerve and carpal tunnel were evaluated at baseline and 3 and 12 months after ECTR. The paired t test was used to compare MRI parameters before and after ECTR and their relationships to clinical improvement scores. RESULTS. All patients' conditions improved after ECTR with mean clinical improvement scores of 2.94 ± 1.0 at 3 months and 3.49 ± 0.56 at 12 months. Although median nerve swelling did decrease proximally, the nerve remained swollen (> 15 mm2) and flattened in all areas, even 12 months after ECTR. Additional changes occurred in median nerve caliber-change ratio, relative signal intensity, and carpal tunnel cross-sectional area. A retinacular gap was present in 33 (94%) wrists 3 months and six (17%) wrists 12 months after ECTR, and increased retinacular bowing persisted. CONCLUSION. After ECTR, undue swelling and flattening of the median nerve persist as long as 12 months after surgery, even in patients with a good surgical outcome. One should be wary of using these MRI findings as signs of persistent neural compression. The retinaculum reforms in most patients within 12 months of surgery but with a more bowed configuration.

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Radiation exposure with repeated radiography required at follow-up poses serious health concerns for scoliosis patients. Although spinous process angle (SPA) measurement of spinal curvatures with ultrasound has been reported with promising results, an evidence-based account on its accuracy for translational application remains undefined. This prospective study involved 952 idiopathic scoliosis patients (75.7% female, mean age 16.7 ± 3.0 y, Cobb 28.7 ± 11.6°). Among 1432 curves (88.1%) detected by ultrasound, there was good correlation between radiologic Cobb angles measured manually on EOS (E_Cobb) whole-spine radiographs and automatic ultrasound SPA measurement for upper spinal curves (USCs) (r = 0.873, apices T7-T12/L1 intervertebral disc) and lower spinal curves (LSCs) (r = 0.740, apices L1 or below) (p < 0.001). Taller stature was associated with stronger correlation. For E_Cobb <30°, 66.6% USCs and 62.4% LSCs had absolute differences between E_Cobb and predicted Cobb angle calculated from SPA ≤5°. Ultrasound could be a viable option in lieu of radiography for measuring coronal curves with apices at T7 or lower and Cobb angle <30°.

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PURPOSE: To retrospectively review the imaging characteristics of CT artefacts due to air bubbles within the oil cooling system of the X-ray tube housing. MATERIALS AND METHODS: Air bubbles were introduced into the oil cooling system of the X-ray tube housing during tube replacement in one of the CT scanners in the authors' institution. All 126 CT brain studies performed in this period were retrospectively reviewed. One hundred and four studies were negative for artefacts. Artefacts were confirmed in 5 and considered probable in 17 studies, respectively. The imaging characteristics of artefacts in these 22 cases were analysed. RESULTS: All artefacts manifested as ill-defined hypoattenuations in the periventricular/subcortical white matter of bilateral cerebral hemispheres with/without involvement of the internal capsule and basal ganglia. The posterior fossa was also involved in two (40%) confirmed and four (24%) probable studies. A band-like configuration of hypoattenuations on sagittal images was observed in five (100%) confirmed and eight (47%) probable studies. CONCLUSION: Air bubble artefacts manifested as hypoattenuations in the periventricular/subcortical white matter of the supratentorial brain. A characteristic band-like configuration was observed in the sagittal reformatted image, which is useful for differentiating it from periventricular small vessel disease.

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Ultrasound (US) is increasingly being used as the first-line imaging modality for investigating the chest wall for soft tissue and bony lesions. This article describes the technique used for the US examination, the relevant chest-wall anatomy, and the appearances on US scanning of pathologic entities either unique to or common in the region of the chest wall.

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Primary musculoskeletal lymphoma presenting as monoarthritis is very rare. Less than 20 cases have been reported. The ultrasound appearances have not been reported to date. We present a young female of primary knee lymphoma with synovial involvement presenting as monoarthritis. The ultrasound and MRI features are discussed.

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OBJECTIVE: The objective of our study was to evaluate the diagnostic accuracy of ultrasound in assessing musculoskeletal soft-tissue tumors superficial to the investing fascia. MATERIALS AND METHODS: Seven hundred fourteen superficial soft-tissue tumors evaluated with ultrasound by two musculoskeletal radiologists were retrospectively reviewed. In all ultrasound reports, the reporting radiologists provided one, two, or three diagnoses depending on their perceived level of diagnostic certainty. Two hundred forty-seven tumors had subsequent histologic correlation, thus allowing the accuracy of the ultrasound diagnosis to be determined. Images of the lesions with a discordant ultrasound diagnosis and histologic diagnosis were reviewed, and the ultrasound features were further classified as concordant with the known histologic diagnosis, concordant with the known histologic diagnosis with atypical features present, or discordant with the known histologic diagnosis. Four hundred sixty-seven tumors without pathologic confirmation were followed up clinically. RESULTS: Overall the accuracy of ultrasound examination for assessing superficial soft-tissue masses was 79.0% when all differential diagnoses were considered and 77.0% when only the first differential diagnosis was considered. The sensitivity and specificity of the first ultrasound diagnosis were 95.2% and 94.3%, respectively, for lipoma; 73.0% and 97.7% for vascular malformation; 80.0% and 95.4% for epidermoid cyst; and 68.8% and 95.2% for nerve sheath tumor. Reduced observer awareness of specific tumor entities tended to contribute to underdiagnosis more than poor specificity of ultrasound findings. Most tumors (236/247, 96%) were benign. The sensitivity and specificity of ultrasound for identifying malignant superficial soft-tissue tumors was 94.1% and 99.7%, respectively. CONCLUSION: The diagnostic accuracy of ultrasound in the assessment of superficial musculoskeletal soft-tissue tumors is high and can be improved through increased radiologist awareness of less frequently encountered tumors. Ultrasound is accurate for differentiating benign from malignant superficial soft-tissue tumors.

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Radial wrist pain is a common clinical complaint. The relatively complex anatomy in this region, combined with the small size of the anatomical structures and occasionally subtle imaging findings, can pose problems when trying to localize the exact cause of pain. To fully comprehend the underlying pathology, one needs a good understanding of both radial-sided wrist anatomy and the relative merits of the different imaging techniques used to assess these structures. In part I of this review, these aspects will be discussed.

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Pain on the radial side of the wrist is a common clinical presentation. Such wrist pain may provide a diagnostic challenge for radiologists, in view of the small size of the anatomic structures, the occasional subtlety of the imaging findings, the diversity of potential etiologies, as well as the non-infrequent occurrence of incidental asymptomatic findings in this area. This review discusses the imaging findings in both the more common and less common causes of radial-sided wrist pain, concentrating particularly on the detection of early disease and less readily apparent abnormalities.

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The buttock is a common site of pathology and ultrasound and is often the first-line imaging modality to examine soft tissue lesions of the buttock region. This review describes the ultrasound technique used, the relevant ultrasound anatomy, and the sonographic appearances of common and uncommon pathological conditions found in the buttock region.

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Phalangeal microgeodic disease is a rare disease that is frequently (though not invariably) related to cold exposure. In most cases, the clinical and radiographic findings of phalangeal microgeodic disease are sufficient to reach the diagnosis. The magnetic resonance imaging (MRI) findings of phalangeal microgeodic disease have been described in four cases in the English literature with two additional cases presented here. MRI allows a greater appreciation of affected bone areas and adds specificity to radiography with regard to diagnosis. In this sense, MRI is a helpful investigation in those cases of phalangeal microgeodic disease when doubt still exists following clinical and radiographic assessment.

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Our purpose was to determine the relationship between tibiofemoral translation on magnetic resonance imaging and clinical instability of the knee following anterior cruciate ligament (ACL) injury. Within 66 patients (43 males, 23 females, mean age 30.25 years), 15 of 19 patients (80%) with an intact ACL had a demonstrable normal screw home movement, while 24 of 47 patients (51%) with an ACL tear had absence of the screw home movement. Patients with clinical instability had greater tibial translation and excursion at the lateral compartment (P=.0001). Following ACL injury, there is demonstrable absence of the normal screw-home movement with anterior tibial translation and excursion related to presence of clinical instability.

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OBJECTIVE: The purpose of our study was to investigate the usefulness of MRI in assessing capsular laxity in patients with recurrent shoulder dislocation. MATERIALS AND METHODS: The records of 64 consecutive patients (the study group consisted of 58 patients, 45 male and 13 female; average age, 39.3 years; range, 13-82 years) who underwent MR arthrography between October 2002 and May 2008 were retrospectively reviewed. The patients were divided into three groups: group A, no shoulder dislocation; group B, first dislocation; and group C, recurrent dislocation. The maximum capsular widths at the anterior, anteroinferior, and inferior regions in the neutral and abducted and externally rotated (ABER) positions were measured on oblique sagittal images. The relationship of capsular width with the number of dislocations, type of capsular attachment, presence of anteroinferior labral tear, and patient sex were evaluated. The sensitivity and specificity of MRI and clinical tests in detecting capsular laxity were also calculated. RESULTS: Among all three patient groups, there were significant differences (p < 0.05) in the widths with the shoulder in the ABER position and the degree of capsular tightening at the anterior region. The average maximum width was largest in group C and smallest in group A. There was a significant difference in the degree of anterior capsular tightening in groups B and C. A moderate correlation of capsular width and anterior tightening (R = -0.45) with number of shoulder dislocations was found. There was a significant difference in capsular width and capsular tightening in relation to the presence of an anteroinferior labral tear. The sensitivity and specificity to detect capsular laxity were 92% and 100%, respectively, for clinical tests and 85% and 96% for MRI. CONCLUSION: MRI is a useful and objective method to assess capsular laxity in patients with recurrent shoulder dislocation.

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