Imaging Characteristics of the Proximal Lateral Collateral Ligament of the Knee: Findings on Ultrasound and MRI With Histologic Correlation.

OBJECTIVES: Determine prevalence of increased signal intensity of the lateral collateral ligament (LCL) of the knee on MRI and decreased echogenicity on ultrasound, and compare with cadaveric histologic evaluation. METHODS: After IRB approval of this prospective study with informed consent, patients having knee MRI were additionally evaluated with ultrasound. Signal intensities of LCL on MRI (low, intermediate, high), echogenicity at ultrasound (hyperechoic, hypoechoic, anechoic), and extent of findings were assessed. Descriptive statistics, Wilcoxon signed ranked test, and intraclass correlation coefficient (ICC) were calculated. Two cadaveric knees were imaged with MRI and ultrasound, including histologic LCL evaluation. RESULTS: Seventy-three subjects were included (39 males, 34 females; mean age 48 ± 14 years) with 77 knee examinations. On MRI, low, intermediate, and high signals were present in 21% (16/77), 75% (58/77), and 4% (3/77), respectively. On ultrasound, echogenicity was assessed as hyperechoic, hypoechoic, and anechoic in 62% (48/77), 38% (29/77), and 0% (0/77), respectively. Mean length of increased signal was 8.6 mm (±4.9) on MRI, and 6.5 mm (±4.8) on ultrasound. The ICC showed a good to excellent intermodality reliability (0.735-0.899) without statistically significant difference for interreader measurements (P = .163-.795). Histology evaluation showed transition of ligament fibers to fibrocartilage at its insertion with increased connective tissue mucin corresponding to MRI and ultrasound findings. CONCLUSIONS: Increased signal intensity of the proximal LCL on ultrasound and MRI is common and corresponds to normal connective tissue mucin.

Ultrasound of the Knee: Common Pathology Excluding Extensor Mechanism.

Ultrasound can be used to diagnose many types of pathology and guide various diagnostic or therapeutic procedures. The most common applications for musculoskeletal ultrasound of the knee include evaluation of the joint recesses, the extensor mechanism, and bursae including Baker's cyst. However, a role exists for ultrasound in the evaluation of cartilage, other tendons, ligaments, peripheral nerves, osseous structures, and vasculature. This article reviews common pathologies of these structures as seen with ultrasound. In addition, various ultrasound-guided procedures pertaining to these pathologies are introduced. The importance of a comprehensive evaluation is also emphasized as a method to maximize information gained from the ultrasound examination.

Tibial bowing in children - what is normal? A radiographic study.

PURPOSE: To define osseous landmarks on tibia radiographs in order to establish age-related normal values characterizing physiological tibial bowing in children. MATERIALS AND METHODS: Five hundred and twenty-six patients aged 0-17 years with normal radiographs of the lower legs were identified and retrospectively reviewed by two blinded radiologists. In anteroposterior (ap)/lateral (lat)-views, 3 lines defined tibial length and angulation. Line-A connecting proximal to distal corner of tibial metaphysic, lines B and C corresponding to corners of tibial metaphysis. Angle A/B defines proximal, A/C distal tibial-angulation. Tibial curvature is defined by distance of line-D parallel to A and tangential to tibial cortex. Normal values were calculated with linear-regression. Intra-/Interreader agreement were tested with a Bland-Altman-plot. RESULTS: Intrareader-agreement: Reader 1 showed a bias of -0.1, standard-deviation of bias was 1.9 and 95 %-limits-of-agreement -3.9- 3.7. Reader 2: -0.01, 2.4 and -4.7- 4.7. Interreader: 0.2, 1.6 and -2.9- 3.3. Angle-A/B ap was 80-100°, increasing with age (86.5-88); angle-AC ap was 82-107°(96.8-90.5), angle-AB lat was 81-107°(93.0-98.0); angle-AC lat was 76-102 (89.5-86.5); depth of curve ap was 0-11 % (8-3.5) and lat 2-13 %, (8.5-3.5). CONCLUSION: Age dependent tibial bowing can be assessed with this new measurement system and age-related normal-values characterizing physiological tibial bowing in children is established. KEY POINTS: • Tibial Bowing is diagnosed on conventional radiographs. • Existing Methods provide limited level of confidence. • New methods provide easy to assess landmarks in all patient ages. • Existing methods require higher radiation dose compared to new method presented.

Prevalence of the acetabular sublabral sulcus at MR arthrography in patients under 17 years of age: does it exist?

PURPOSE: To retrospectively determine characteristics of contrast-filled acetabular labral clefts in patients under the age of 17 years at MR arthrography (Mra) correlated with arthroscopy, which may impact the thinking regarding the existence of a sublabral sulcus. MATERIALS AND METHODS: After IRB approval, 41 patients under the age of 17 who had MRa were identified. The following observations of contrast-filled clefts were assessed: (1) presence/absence, (2) location, (3) depth, (4) abnormal signal within the labrum and (5) shape (linear, gaping, complex). Fisher's exact and the Wilcoxon matched-pairs signed-rank test were performed. Interreader agreement was calculated with Cohen's k. RESULTS: Reader 1 found clefts in 41 %. Depth was less than half in 6%, more than half in 65% and full thickness in 29%. Shape was linear in 53%, gaping in 18% and complex in 29%. Signal changes occurred in 88%. Reader 2 found clefts in 29%. Depth was less than half in 17%, more than half in 58% and full thickness in 25%. Shape was linear in 50%, gaping in 42% and complex in 17%. Signal changes occurred in 50%. None of the clefts fulfilled the criteria for a sublabral sulcus at MRa and arthroscopy. CONCLUSION: None of the clefts found in our subjects under the age of 17 years met the MRa and arthroscopy criteria for a sublabral sulcus, which supports the theory that such clefts represent labral tears.

Femoroacetabular cam-type impingement: global assessment of the femoral head-neck junction on a single reformatted MR image.

PURPOSE: To characterize the imaging appearance of femoral head-neck contour abnormalities on a short-axis magnetic resonance (MR) image compared with the usual anterior alpha angle measurements and multiple alpha angle measurements on radial reformatted MR images, with surgery as the reference standard. MATERIALS AND METHODS: After institutional review board approval of this HIPAA-compliant study, 21 patients who underwent arthroscopy and 24 patients who did not, all of whom were evaluated with three-dimensional MR imaging, during 1 year were identified. Short-axis MR images of the femoral head-neck junction were reformatted with multiple radial images along the axis of the femoral neck. The following measurements were made at each hour of a clock face: (a) presence and size of bone contour abnormality visible beyond a best-fit circle and (b) femoral head-neck offset angles. Mann-Whitney, Fisher exact, and Wilcoxon matched-pair signed rank tests were performed. Intra- and interreader agreement were calculated as the Cohen κ. RESULTS: Of the 21 subjects who underwent surgery, 16 were confirmed to have cam-type femoroacetabular impingement (FAI) at surgery. Comparing findings from short-axis images with those at surgery, average accuracy was 81%. Comparing findings from head-neck offset angles with those at surgery, average accuracy was 80%. On short-axis images, average bone elevation was 3.2 mm in patients with cam-type FAI and 1.4 mm in those without it. In eight of 24 subjects who did not undergo surgery, the alpha angle was normal but the short-axis MR image showed abnormal bone contour. CONCLUSION: An abnormal bone contour identified on a short-axis MR image at the femoral head-neck junction correlates with surgical findings and may allow for a global characterization of the bone abnormality with regard to location, extent, and amount of elevation compared with the alpha angle and multiple head-neck offset angles.

Distal pectoralis major tears: sonographic characterization and potential diagnostic pitfalls.

OBJECTIVES: Distinction between musculotendinous tears of the pectoralis major and distal tendon avulsions is important, as the latter typically requires surgical repair. The objective of this study was to characterize the sonographic appearances of surgically proven distal tendon avulsion tears of the pectoralis major. METHODS: A retrospective search of the radiology database (2001-2011) revealed 22 cases of pectoralis major tears on sonography, of which 9 had surgical correlation. Sonograms were retrospectively characterized by 3 fellowship-trained musculoskeletal radiologists in consensus with respect to the location and size of the fluid collection and the presence of tendon or tendonlike tissue superficial to the biceps brachii tendon. RESULTS: At surgery, complete distal tendon avulsions or tears of the sternal head of the pectoralis were present in all 9 cases: isolated in 6 and combined with clavicular head tears in 3. The location of the fluid collection was at the musculotendinous junction in 89% (8 of 9) and medial to the biceps brachii tendon in 11% (1 of 9), with a mean largest dimension of 3.8 cm (range, 0.7-6.2 cm). In no case was fluid seen at the humeral attachment of the pectoralis. In 67% (6 of 9), linear thickened hypoechoic tissue was seen superficial to the biceps brachii tendon, which simulated an abnormal but intact tendon, whereas in 33% (3 of 9), a normal distal pectoralis tendon was seen. CONCLUSIONS: Surgically proven distal pectoralis major tendon avulsions most commonly showed fluid collections at the musculotendinous junction and not at the humeral shaft, with either a normal tendon or hypoechoic tendonlike tissue over the biceps brachii long-head tendon. These findings may potentially cause misdiagnosis of distal tendon avulsions or tears as musculotendinous injuries.

Capsular laxity of the hip: findings at magnetic resonance arthrography.

PURPOSE: The purpose of this study was to retrospectively investigate magnetic resonance (MR) arthrography imaging findings associated with capsular laxity of the hip joint found at surgery. METHODS: After institutional review board approval, 27 patients who had arthroscopy reports that described the presence or absence of capsular laxity of the hip joint were identified over a 2-year period. Preoperative MR images were retrospectively reviewed by 2 blinded radiologists. The following observations were recorded: (1) thickness, signal intensity, and defects of the anterior joint capsule; (2) thickness and signal intensity of the zona orbicularis; (3) width of the anterior and posterior joint recesses at the level of the femoral head; (4) presence of synovitis in the anterior joint recess; and (5) volume of intra-articular contrast and degree of hip rotation. Intrarater and inter-rater agreement was assessed. RESULTS: Of the 27 patients, 17 were positive and 10 were negative for hip joint laxity at arthroscopy. The mean thickness of the anterior hip capsule was significantly different (P = .0043), measuring 2.5 mm (95% confidence interval [CI], 2.3 to 2.8 mm) in those with hip laxity and 3.3 mm (95% CI, 2.8 to 3.8 mm) in those without laxity. The mean width of the anterior joint recess was 5.8 mm (95% CI, 5.4 to 6.3 mm) in those with laxity and 3.6 mm (95% CI, 3.3 to 3.9 mm) in those without laxity and was significantly different (P < .0001). No other variables were considered useful because of a lack of significant differences between the 2 patient groups or low inter-rater agreement. CONCLUSIONS: On the basis of 95% CIs, hip joint laxity at MR arthrography is associated with widening of the anterior hip joint recess (>5 mm) and thinning of the adjacent joint capsule (<3 mm) lateral to the zona orbicularis.

Paralabral cysts in the hip joint: findings at MR arthrography.

PURPOSE: The purpose of this research was to retrospectively characterize paralabral cysts of the hip as seen at MR arthrography. MATERIALS AND METHODS: After Institutional Review Board approval, 704 patients who had MR arthrography were identified over a 3-year period and 40 patients were identified as having a cyst or fluid collection at the hip by MR report. MR images from these 40 patients were retrospectively reviewed by three radiologists where 18 were found to have a paralabral cyst, which were characterized as follows: location, configuration, contrast filling, size of the cyst, extent, direction, and whether associated osseous changes were present. In addition, the acetabular labrum was assessed for tears and, if present, the location and pattern were characterized. RESULTS: Paralabral cysts were located anterosuperiorly in 56%, anteriorly in 22%, posterosuperiorly in 17%, and anteroinferiorly in 6% of cases. The vast majority (94%) were multilocular and filled with intra-articular contrast medium. The average dimensions were 8 × 7 × 11 mm. The paralabral cyst demonstrated extracapsular extension in 72% of cases, with 39% located between the ilium and gluteus minimus, and 22% between the ilium and iliopsoas. Remodeling of the ilium adjacent to the cyst was observed in 50% of these cases. A labral tear was at the base of the labrum adjacent to the cyst in 78% of cases, while the tear was isolated to the body of the labrum in 22%. Tears were most commonly anterosuperior (55%) or anterior (28%) in location. CONCLUSION: Our results show that paralabral cysts of the hip are most commonly located anterosuperiorly, are multilocular, fill with intra-articular contrast medium, have average dimensions up to 11 mm, and often extend extracapsularly between muscle and bone where they may remodel the adjacent ilium.

Plate Fixation for Irreducible Proximal Humeral Fractures in Children and Adolescents-A Single-Center Case Series of Six Patients.

BACKGROUND: Recommended treatment for severely displaced proximal humeral fractures in children is the closed reduction and percutaneous fixation by K-wires or intramedullary nailing. METHODS: From January 2016 to January 2017 6, 21 children/adolescents (range 8 to 16 years) with proximal humeral fractures were treated surgically for severe displacement. In these six patients, several attempts of closed reduction were unsuccessful, and an open reduction was performed. The humeral head was fixed with a 3.5 mm T-plate without affecting the growth plate. Plate removal was performed at a mean interval of 132 days after initial surgery. Two years after initial surgery, the clinical outcome was assessed by the Constant-Murley score and QuickDASH score (including sport/music and work) and the shoulder joint was evaluated with a standardized sonographic examination for the rotator cuff and the conjoint tendon. RESULTS: In all six patients, dorsal displacement of the fracture was irreducible due to the interposition of tendinous or osseous structures. Intraoperatively, the interposed structures were the long biceps tendon in two, periosteal tissue in two, a bony fragment in one, and the long biceps tendon together with the conjoint tendon in one case. At mean follow-up of 26 months (range 22 months to 29 months), patients showed very good clinical results with an excellent mean Constant-Murley score of 97.5 (range 91 to 100) and mean QuickDASH score (including sport/music and work) of 5.5 (range 0-20.8). An X-ray follow-up 6 weeks after surgery demonstrated early consolidation and correct alignment in all patients. A sonographic evaluation at 2 years post injury showed that the biceps and the conjoined tendon were intact in all patients. CONCLUSIONS: If a proximal humeral fracture is not reducible by closed means, a tissue entrapment (most likely biceps tendon) should be considered. Treatment with an open reduction and plate fixation yields very good clinical and radiological results and preserves interposed structures as the biceps and conjoint tendon.

Radiographic evaluation of frontal talar edge configuration for osteochondral plug transplantation.

For successful reconstruction of osteochondral lesions of the talus, the anatomic configuration of the talar edge must be respected. This study evaluated the radiographic configuration of the talar edge in the anterior-posterior (AP) view by analyzing medial and lateral talar edge angles and radii in 81 patients with a true AP view and without ankle pathology. The mean lateral talar edge angle was 91.8 degrees , and the mean medial talar edge angle was 110.0 degrees . The medial frontal talar edge radius was 4.8 mm and the lateral 3.5 mm, respectively. No correlation between angle and radius was found. These results revealed a significant difference between the medial and the lateral talar edge configuration. This may be due to the three-dimensional function of the human ankle joint. No study so far has addressed these differences radiologically. These differences should be addressed in the reconstruction of osteochondral lesions and be included in the preoperative planning.

Standardized Haller and Asymmetry Index Combined for a More Accurate Assessment of Pectus Excavatum.

BACKGROUND: The measurement of the Haller index (HI) is not standardized, and HI does not consider the asymmetry of pectus excavatum. The aim of this study was to determine the most appropriate level for measuring the HI and to introduce the asymmetry index (AI) in order to respect the aspect of asymmetry. METHODS: Preoperative computer tomography scans of 43 patients with pectus excavatum were retrospectively analyzed by measuring both the HI and the AI at 3 different levels: (I) sternomanubrial junction; (II) caudal end of corpus sterni; and (III) tip of the xiphoid. The control group comprised 33 patients without chest wall deformity and a HI < 3.25. For each patient HI and AI were calculated according to a standardized protocol. A McNemar test was used for statistical analyses. RESULTS: The sensitivity of the HI was highest when measured at level II (p < 0.388), and the AI exhibited the highest sensitivity at level I. When combining both indices, the sensitivity of assessing pectus excavatum significantly increased compared with the use of HI at level II alone (p < 0.002). CONCLUSIONS: The measurement of the HI at level II represents the most valid standardized parameter for assessment of the severity of pectus excavatum. Asymmetry, on the other hand, is best assessed by the AI measured at level I. The combination of the standardized HI and AI not only provides a much more accurate description of pectus excavatum, but also improves the comparability of pectus excavatum patients in general.

The effect of osseous ankle configuration on chronic ankle instability.

BACKGROUND: Chronic ankle instability (CAI) is a common orthopaedic entity in sport. Although other risk factors have been studied extensively, little is known about how it is influenced by the osseous joint configuration. AIM: To study the effect of osseous ankle configuration on CAI. DESIGN: Case-control study, level III. SETTING: Radiological examination with measurement of lateral x rays by an independent radiologist using a digital DICOM/PACS system. PATIENTS: A group of 52 patients who had had at least three recurrent sprains was compared with an age-matched and sex-matched control group of 52 healthy subjects. MAIN OUTCOME MEASURES: The radius of the talar surface, the tibial coverage of the talus (tibiotalar sector) and the height of the talar body were measured. RESULTS: The talar radius was found to be larger in patients with CAI (21.2 (2.4) mm) than in controls (17.7 (1.9) mm; p<0.001, power >95%). The tibiotalar sector, representing the tibial coverage of the talus, was smaller in patients with CAI (80 degrees (5.1 degrees )) than in controls (88.4 degrees (7.2 degrees ); p<0.001, power >95%). No significant difference was observed in the height of the talar body between patients with CAI (28.8 (2.6) mm) and controls (27.5 (4.0) mm; p = 0.055). CONCLUSION: CAI is associated with an unstable osseous joint configuration characterised by a larger radius of the talus and a smaller tibiotalar sector. There is evidence that a higher talus might also play some part, particularly in women.

Increased Magnetic Resonance Imaging Signal of the Lateral Patellar Facet Cartilage: A Functional Marker for Patellar Instability?

BACKGROUND: In the knee joint, predisposition for patellar instability can be assessed by an abnormal Insall-Salvati index, tibial tuberosity-trochlear groove (TTTG) distance, and abnormal shape of patella and trochlea. Given the complex anatomic features of the knee joint with varying positions of the patella during motion, the presence of a single or even a combination of these factors does not inevitably result in patellar instability. After trocheoplasty in patients with trochlear dysplasia, assessment of trochlear cartilage and subchondral bone is limited due to postoperative artifacts. Identification of presence of edema in the patellar cartilage may be helpful to identify patellar instability before and after surgery in these patients. PURPOSE: To determine whether increased signal intensity of the lateral patellar facet cartilage or measurements of abnormal patellofemoral articulation are associated with patellar instability before and after trochleoplasty. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Twenty-two patients with clinical diagnosis of patellar instability who underwent trochleoplasty, with magnetic resonance imaging (MRI) of the knee before and after surgery, were identified. The following observations and measurements were obtained in preoperative imaging: Insall-Salvati ratio, tibial tuberosity-trochlear groove (TTTG) distance, patellar shape (Wiberg), trochlear shape (Hepp), and edema in the lateral patellar facet cartilage. At 3 to 12 months after surgery, the presence or absence of edema in the cartilage of the lateral facet of the patella, the trochlear shape, and TTTG distance were reassessed. Wilcoxon matched-pairs signed rank test and Student t test were used. Interreader agreement was calculated as the Cohen κ or paired Student t test. RESULTS: Increased cartilage signal was present in 20 patients before trochleoplasty and in 4 after trochleoplasty. Insall-Salvati ratio was greater than 1.20 in 20 patients. Patellar shape was greater than type 2 in 18 patients. Trochlear shape was greater than type 2 in 21 patients before and 7 after trochleoplasty. Mean TTTG distance was 14 mm before and 10 mm after surgery. When results before and after surgery were compared, a significant difference was found for cartilage signal, TTTG distance, and trochlear shape. Agreement for observations was moderate to substantial, and no significant differences were found for interreader agreement ( P > .05). CONCLUSION: Patellar cartilage at the lateral facet of the patella can be assessed after trochleoplasty despite postoperative artifacts in the trochlea. A decrease of patellar edema seems to be associated with improved femoropatellar articulation. Moreover, patellar edema may be used as a functional criterion of patellofemoral instability. This would provide additional information compared to morphologic criteria which just describe predisposing factors for femoropatellar instability.

Evaluation of hindfoot dimensions: a radiological study.

BACKGROUND: Realignment of the foot and good ligament balancing are mandatory for successful reconstruction of complex hindfoot disorders. This is why references for restoration of the normal anatomy and function are necessary when considering surgical reconstruction, such as osteotomies, arthrodeses, and total ankle replacement. However, no data are available regarding the normal anatomical dimensions on standard radiographs of the hindfoot. The purpose of this radiographic study was to define relevant and reproducible measures on lateral hindfoot radiographs and to assess their reliability. METHODS: Lateral radigraphic views were taken of 100 consecutive patients (37 women, 63 men) who consulted the emergency room for foot trauma. Dimensions assessed were the talar coverage by the tibia, the angle of the distal tibial joint plane to the tibial axis (tilt), the width of the tibia, the height of the talus, the joint radius of the ankle joint, and the offset of the center of rotation from the tibial axis. RESULTS: The tibial coverage of the talus was 88.1 (SD = 6.7) degrees, the tibial tilt was 83 (SD = 3.6) degrees, the width of the distal tibia was 33.6 mm (SD = 3.6 mm), the radius of the ankle joint was 18.6 mm (SD = 2.3 mm) with an anterior offset of the center of rotation of 1.7 mm (SD = 2.1 mm), and the height of the talus was 28.2 mm (SD = 4.0 mm). CONCLUSIONS: Several easily accessible measures on radiographs were found to be reliable in describing normal hindfoot anatomy and therefore may be used to evaluate hindfoot disorders. Additionally, because any reconstruction of the hindfoot should aim to correct the feet in a physiological way, these references may be helpful in the preoperative planning for treatment of complex deformities and posttraumatic disorders.

The surgical tibiotalar angle: a radiologic study.

BACKGROUND: Many studies on cadaver specimens describe the hindfoot anatomy, but few measures have been defined and quantified on radiographs. Our aim was to determine the tibiotalar angle using the tibial tuberosity as a reference point. METHODS: The tibiotalar angle, using the tibial tuberosity as reference point, was measured on anteroposterior views of 168 ankles. Bilateral radiographs were obtained in 75 patients. RESULTS: The tibiotalar angle was 92.4 degrees (SD = 3.1) without significant intraindividual difference on the radiographs examined bilaterally. More varus was found in women and with increased age. CONCLUSIONS: The tibial tuberosity is a reliable reference point for the measurement of the tibiotalar angle and is used in numerous operative procedures of the hindfoot. If the angle cannot be measured because of progressed destruction, the measurement can be obtained from the contralateral leg, as no significant intraindividual difference was found in the tibiotalar angle (p < 0.001).

MR imaging appearances of soft tissue flaps following reconstructive surgery of the lower extremity.

MR imaging appearances of different types of reconstructive muscle flaps following reconstructive surgery of the lower extremity with associated post-surgical changes due to altered anatomy, radiation, and potential complications, can be challenging. A multidisciplinary therapeutic approach to tumors allows for limb salvage therapy in a majority of the patients. Decision-making for specific types of soft tissue reconstruction is based on the body region affected, as well as the size and complexity of the defect. Hematomas and infections are early complications that can jeopardize flap viability. The local recurrence of a tumor within six months after a complete resection with confirmed tumor-free margins and adjuvant radiation therapy is rare. Identification of a new lesion similar to the initial tumor favors a finding of tumor recurrence.