Advantages of CT Versus MRI for Preoperative Assessment of Osteochondritis Dissecans of the Capitellum.

BACKGROUND: Magnetic resonance imaging (MRI) is considered to be the gold standard for imaging of osteochondritis dissecans (OCD). PURPOSE/HYPOTHESIS: The purpose was to determine the additional value of a preoperative computed tomography (CT) scan in adolescent patients with capitellar OCD of the elbow. Consistent with the fact that OCD is a lesion involving the subchondral bone, the hypothesis was that CT would be superior to MRI for imaging OCD of the capitellum. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: All patients being treated surgically for an OCD of the capitellum between 2006 and 2016 at one institution were reviewed for preoperative imaging. A total of 28 patients met the inclusion criteria. Corresponding MRI and CT scans were compared retrospectively. Multiple parameters were recorded, with special emphasis on OCD lesion size, fragmentation, and tilt as well as joint surface integrity, loose bodies, and osteophytes. RESULTS: The OCD lesions were best seen on CT scans, whereas MRI T1-weighted images overestimated and T2-weighted images underestimated the size of defects. A subchondral fracture nonunion was found on CT scans in 18 patients, whereas this was seen on MRI T1-weighted images in only 2 patients (P < .001) and MRI T2-weighted images in 4 patients (P < .001). Fragmentation of the OCD fragment was found on CT scans in 17 patients but on MRI scans in only 9 patients (P = .05). Osteophytes as a sign of secondary degenerative changes were seen on CT scans in 24 patients and were seen on MRI scans in 15 patients (P = .02). Altogether, only 51 of 89 secondary changes including loose bodies, effects on the radial head and ulnohumeral joint, and osteophytes that were seen on CT scans were also seen on MRI scans (P = .002). CONCLUSION: OCD fragmentation and secondary changes were more often diagnosed on CT. These factors indicate OCD instability or advanced OCD stages, which are indications for surgery. In an adolescent who is considered at risk for OCD (baseball, gymnastics, weightlifting, tennis) and who has lateral elbow joint pain with axial or valgus load bearing, CT is our imaging modality of choice for diagnosing and staging OCD of the capitellum.

A simple method of measuring tibial tubercle to trochlear groove distance on MRI: description of a novel and reliable technique.

PURPOSE: Tibial tubercle-trochlear groove (TT-TG) distance is a variable that helps guide surgical decision-making in patients with patellar instability. The purpose of this study was to compare the accuracy and reliability of an MRI TT-TG measuring technique using a simple external alignment method to a previously validated gold standard technique that requires advanced software read by radiologists. METHODS: TT-TG was calculated by MRI on 59 knees with a clinical diagnosis of patellar instability in a blinded and randomized fashion by two musculoskeletal radiologists using advanced software and by two orthopaedists using the study technique which utilizes measurements taken on a simple electronic imaging platform. Interrater reliability between the two radiologists and the two orthopaedists and intermethods reliability between the two techniques were calculated using interclass correlation coefficients (ICC) and concordance correlation coefficients (CCC). ICC and CCC values greater than 0.75 were considered to represent excellent agreement. RESULTS: The mean TT-TG distance was 14.7 mm (Standard Deviation (SD) 4.87 mm) and 15.4 mm (SD 5.41) as measured by the radiologists and orthopaedists, respectively. Excellent interobserver agreement was noted between the radiologists (ICC 0.941; CCC 0.941), the orthopaedists (ICC 0.978; CCC 0.976), and the two techniques (ICC 0.941; CCC 0.933). CONCLUSION: The simple TT-TG distance measurement technique analysed in this study resulted in excellent agreement and reliability as compared to the gold standard technique. This method can predictably be performed by orthopaedic surgeons without advanced radiologic software. LEVEL OF EVIDENCE: II.

Variability of the Ischiofemoral Space Relative to Femur Position: An Ultrasound Study.

BACKGROUND: Ischiofemoral impingement is caused by compression of the quadratus femoris muscle between the ischial tuberosity and lesser trochanter. The evaluation of ischiofemoral impingement includes radiologic studies to evaluate the ischiofemoral space dimensions. No prior study has evaluated the effect of femoral position on ischiofemoral space dimensions. OBJECTIVE: To determine whether the dimensions of the ischiofemoral space vary with changes in femoral position. DESIGN: Cross-sectional study. SETTING: Academic institution. PARTICIPANTS: Six male and four female subjects with no hip pain and no history of hip disorders or surgery were selected to participate in the study. The subjects' mean age was 31.5 years; mean height, 176.8 cm; mean weight, 70.2 kg; and mean body mass index, 23.6 kg/m(2). METHODS: Ultrasound was used to measure the ischiofemoral space in bilateral gluteal regions of each volunteer. The volunteers underwent imaging in a prone position. The ischiofemoral space was measured with the femur in 9 different positions created through various combinations of frontal (15° abduction, neutral, and 15° adduction) and transverse (30° internal rotation, neutral, and 30° external rotation) plane hip motions. MAIN OUTCOME MEASUREMENTS: The narrowest ischiofemoral interval, defined as the narrowest distance between the medial cortex of the lesser trochanter and the lateral cortex of the ischial tuberosity. RESULTS: The anatomic landmarks used to measure the ischiofemoral space were easily identified in all subjects. The frontal plane main effect (F2,18 = 38.611) was statistically significant (P < .001), as was the transverse plane main effect (F2,18 = 82.452, P < .001). These findings indicated that there was a statistically significant difference in ischiofemoral space according to hip position in the frontal and transverse planes. The largest ischiofemoral space measurement occurred with the hip in abduction and internal rotation (51.8 mm; 95% confidence interval [CI], 49.2-54.5 mm), whereas hip adduction and external rotation resulted in the narrowest ischiofemoral space measurement (30.8 mm; 95% CI, 25.5-36.0 mm). The largest difference was between the adduction-external rotation and the abduction-internal rotation positions (mean difference = 21.1 mm; 95% CI, 13.7-28.5 mm; P < .001), and the smallest difference was between the adducted-neutral rotation and the abducted-external rotation positions (mean difference = 0.23 mm; 95% CI, -8.07-8.55 mm; P = .99). CONCLUSIONS: Femoral position affects ischiofemoral space dimensions. The ischiofemoral space widens with abduction and internal rotation and narrows with adduction and external rotation, and thus femoral position should be considered when imaging and measuring the ischiofemoral space.

CT and MRI measurements of tibial tubercle-trochlear groove distances are not equivalent in patients with patellar instability.

BACKGROUND: Tibial tubercle-trochlear groove distance (TT-TG) is a commonly used measurement for surgical decision making in patients with patellofemoral malalignment and instability. This measurement has historically been performed utilizing axial computed tomography (CT). More recently, magnetic resonance imaging (MRI) has been proposed as an equivalent method, but this has not yet been fully validated. PURPOSE: To determine the reliability of TT-TG distance measurements on both MRI and CT and to determine whether the measurements are interchangeable with one another. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: All patients with patellar instability who underwent both CT and MRI of the knee from 2003 to 2011 were included (n = 59 knees in 54 patients). Two fellowship-trained musculoskeletal radiologists measured the TT-TG distances for each patient by CT and MRI in a randomized, blinded fashion. Interobserver reliability was calculated between radiologists for both imaging modalities, and intermethod reliability was calculated between the 2 imaging modalities. The results are reported using intraclass correlation coefficients (ICCs) and Bland-Altman analysis. RESULTS: The 59 knees had a mean TT-TG distance of 16.9 mm (range, 8.3-25.8 mm) by CT and 14.7 mm (range, 1.5-25.1 mm) by MRI. Interobserver reliability between the radiologists was considered excellent for both CT and MRI (ICC = 0.777 and 0.843, respectively). When comparing CT to MRI, the ICC was considered only fair for each of the raters (0.532 and 0.539). Eleven patients (19%) had a TT-TG distance of ≥20 mm on CT preoperatively and underwent distal realignment by tibial tubercle osteotomy. In this surgical subgroup, the mean TT-TG distance was 22.5 mm (range, 19.8-25.8 mm) by CT and only 18.7 mm (range, 14.4-22.8 mm) by MRI for a mean difference of 3.80 mm (P < .001). CONCLUSION: The TT-TG distance can be measured with excellent interrater reliability on both MRI and CT; however, the values derived from these 2 tests may not be interchangeable. This observation should be taken into consideration when MRI is used for surgical planning because MRI may underestimate the TT-TG distance when compared with CT.

Decreased range of motion is associated with structural hip deformity in asymptomatic adolescent athletes.

BACKGROUND: Decreased hip range of motion (ROM) is a common finding in patients with femoroacetabular impingement (FAI). PURPOSE: To report the prevalence of decreased hip ROM in asymptomatic adolescent athletes and to correlate examination findings to signs of FAI on radiographs and magnetic resonance imaging (MRI). STUDY DESIGN: Cross-sectional study (prevalence); Level of evidence, 3. METHODS: A total of 226 adolescent athletes presenting for state-mandated preparticipation physical examinations were assessed. Hip internal rotation was measured with the participant supine and the hip flexed to 90°. All participants with ≤10° of internal rotation were invited to return for standard radiographs and MRI of both hips. An age-matched control group, with >10° of internal rotation, underwent MRI examination only. Twenty-six athletes (13 study and 13 control) returned for clinical and radiographic examinations. RESULTS: Nineteen athletes (34 hips, 8%) were found to have <10° of internal rotation. Eight athletes (13 hips, 3%) also had a positive anterior impingement sign. Thirteen of 19 athletes participated in the radiographic portion of the study. Of these 13 participants, 4 had limited internal rotation unilaterally, leaving 22 hips in the study group. Eight of 13 participants (15 hips, 68%) had a cam-type deformity evident on plain radiographs, and 4 participants (7 hips, 32%) had a positive radiographic crossover sign. The average α angle measured from radial MRI sequences was 58.1° in the study group versus 44.3° in the control group (P < .001). Fifteen hips (68%) in the study group had abnormal MRI findings within the acetabular labrum or cartilage compared with 10 of 26 hips (38%) in the control group (odds ratio, 3.4; P = .078). CONCLUSION: Eight percent of asymptomatic teenagers had limited internal rotation on examination; 68% of these had radiographic findings suggestive of FAI. More than two thirds of these participants had evidence of asymptomatic hip pathological lesions on MRI.

Dual energy computed tomography for quantification of tissue urate deposits in tophaceous gout: help from modern physics in the management of an ancient disease.

Gout has been recognized for centuries but is also a modern day scourge. It is the most common type of inflammatory arthritis in men and appears to be increasing in both incidence and prevalence (Arromdee et al. in J Rheumatol 29(11):2403-2406, 2002). Despite these facts, few advances have been made in the diagnosis and treatment of gout for over 50 years. Difficult cases of gout challenge available therapeutic options. It is only recently that the Food and Drug Administration has approved febuxostat as a treatment option for patients intolerant of allopurinol. We describe a difficult case of tophaceous gout notable for several reasons: utilization of rasburicase as uricolytic treatment to dramatically reduce tissue urate burden; treatment of gout flares with interleukin-1ß inhibition; and quantification of tissue urate with novel dual energy computed tomography technology before and after uricolytic therapy.

Musculotendinous infraspinatus rupture and shoulder weakness.

We report a patient with bilateral simultaneous onset of weakness of shoulder lateral rotation due to musculotendinous infraspinatus rupture that occurred after shoulder steroid injections. Disruption of the musculotendinous junction of the infraspinatus is a rare recently described entity. Electromyography is normal, and magnetic resonance image findings are characteristic.

Evaluation of intraneural ganglion cysts using three-dimensional fast spin echo-cube.

PURPOSE: To compare conventional two-dimensional fast spin echo (FSE) MRI sequences with a three-dimensional FSE extended echo train acquisition method, known as Cube, in the evaluation of intraneural ganglion cysts. Also, to demonstrate that Cube enables the consistent identification and thorough characterization of the cystic joint connection, and therefore improves patient care by superior preoperative planning. MATERIALS AND METHODS: Six patients with intraneural ganglia in the knee region (five involving the peroneal and one the tibial nerve) were evaluated using both conventional FSE MR sequences and the Cube sequence. Studies were interpreted by the consensus of three board certified musculoskeletal radiologists and one peripheral nerve neurosurgeon. Surgical correlation was available in five of the six cases. RESULTS: Both imaging methods demonstrated the cysts and at least part of their joint connections after variable amount of postprocessing. Cube proved superior to conventional imaging in its ability to acquire isotropic data that could easily be reconstructed in any plane and its ability to resolve fine anatomical details. CONCLUSION: Cube is a new MR pulse sequence that enables the consistent identification of the intraneural ganglion cyst joint connection. We believe that improved visualization and characterization of the entire cyst will improve patient outcomes by facilitating more accurate surgical intervention.

MRI accuracy for tears of the posterior horn of the lateral meniscus in patients with acute anterior cruciate ligament injury and the clinical relevance of missed tears.

OBJECTIVE: The sensitivity of MRI for the detection of tears of the posterior horn of the lateral meniscus (PHLM) is lowest compared with that for tears at other meniscal locations, and the presence of simultaneous acute anterior cruciate ligament (ACL) injury decreases overall MRI sensitivity for meniscal tears. We rereviewed surgically proven cases of missed meniscal tears in knees with an acute ACL injury to determine why PHLM tears may be missed. We also investigated whether the missed PHLM tears were clinically significant-that is, if these tears required surgical repair or resection. MATERIALS AND METHODS: We reviewed the medical records of 120 patients (< 40 years old) who underwent arthroscopic ACL reconstruction within 6 weeks after MRI to identify MRI-missed meniscal tears. Missed PHLM tears were categorized as clearly evident, occult, or subtle during MRI rereview. The "two-touch-slice" rule served as the primary criterion for tear diagnosis. Secondary MRI findings, including an abnormal superior popliteomeniscal fascicle and apparent far lateral extension of the meniscofemoral ligament, and additional clinical, surgical, and initial MRI findings were compared between meniscal tear groups. RESULTS: The majority (19/28) of missed tears involved the PHLM: Five were clearly evident at the time of rereview, all of which required surgical treatment; six were occult, none of which was treated; and eight were subtle, four of which were treated. Knees with PHLM tears were more likely to have abnormal superior popliteomeniscal fascicles (p = 0.002) and apparent far lateral extension of the meniscofemoral ligament (p = 0.003) than knees with normal lateral menisci. CONCLUSION: Clearly evident missed PHLM tears would not have been missed if the two-touch-slice rule had been strictly applied at prospective MRI interpretation. Unavoidably missed PHLM tears were not clinically significant. However, there were no clinical or secondary MRI findings specific to missed PHLM tears in the setting of acute ACL injury.

Septic sternoclavicular joint: a case report.

A 23-year-old man presented to our sports medicine clinic with a history of nontraumatic left anterior chest pain. Prior to presentation, a magnetic resonance image (MRI) had been performed that showed increased signal in the soft tissues around the sternoclavicular joint, primarily in the pectoralis major, and a small amount of fluid in the joint, thought possibly consistent with sympathetic effusion from a muscle tear. On examination, the patient was toxic appearing and had severe pain with virtually any left upper-extremity movement and with walking. There was swelling, redness, warmth, and tenderness over the left sternoclavicular joint. Vital signs were normal, but due to concerns of possible septic arthritis, he was admitted to the hospital. After discontinuation of prednisone and hydrocodone-acetaminophen that he had been receiving, the patient became febrile. Blood and sternoclavicular joint aspirate cultures grew methicillin-sensitive Staphylococcus aureus. On re-review of the MRI, subtle abnormal signal compatible with the patient's joint infection was seen. The patient was treated with intravenous antibiotics and, eventually, surgical resection of the left sternoclavicular joint, proximal clavicle, and lateral manubrium with subsequent muscle flap. No predisposing factor for this infection was found. Septic sternoclavicular joint is rare, accounting for 1% of all septic joints. Infection or other unusual pathology should be suspected when clinical findings are not consistent with simple musculoskeletal injury.

Magnetic resonance imaging of surgically confirmed anterior cruciate ligament graft disruption.

OBJECTIVE: To evaluate previously described primary and secondary MRI signs of disruption to anterior cruciate ligament (ACL) grafts in surgically proven cases. MATERIALS AND METHODS: We retrospectively analyzed MR images of 48 patients (mean age 29 years) with clinically suspected ACL graft disruption. All patients had surgical confirmation of the MRI findings. The reviewers analyzed the cases blinded to the surgical results and assessed each of the primary and secondary MRI signs of graft disruption individually. Subsequently, a final impression of the graft integrity based on a comprehensive assessment of all of the primary and secondary findings was made. RESULTS: Utilizing a comprehensive assessment of previously described primary and secondary MR findings of ACL graft disruption, the blinded reviewers were able to identify correctly full-thickness graft tears with test accuracy of 85%, sensitivity of 72%, and specificity of 100%. Individual assessment of the primary finding of graft fiber discontinuity had sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 72%, 100%, 100%, 77% and 85%, respectively, for full-thickness tears. Other individual primary and secondary findings were less reliable; however, the primary findings of marked segmental thinning of the graft and markedly abnormal graft orientation, and the secondary findings of bone contusions in the lateral compartment and large joint effusion, had high specificity and positive predictive value. Of the four missed cases, two had associated arthrofibrosis. CONCLUSION: The comprehensive assessment of previously described primary and secondary MRI findings of ACL graft disruption has high test specificity and moderately high test accuracy. The presence of graft fiber discontinuity is the most reliable primary or secondary finding when assessed individually. Marked segmental thinning of the graft and abnormal fiber orientation, and the presence of bone contusions in the lateral compartment and large joint effusion, are less reliable overall but are highly suggestive of full-thickness graft tear when present.

Survivorship analysis in patients with periosteal chondrosarcoma.

UNLABELLED: To investigate outcome and identify prognostic factors, we retrospectively reviewed 24 consecutive patients with periosteal chondrosarcomas. There were 17 males and seven females with a mean age of 37.6 years (range, 15-73 years). The femur was involved in 12 patients, the proximal humerus in five, the tibia in two, and the distal fibula, ilium, pubis, metatarsal, and rib in one patient each. The mean greatest dimension of the lesions was 8.1 cm (range, 1.5-27 cm). Based on the histologic pattern, there were 18 Grade 1 tumors and six Grade 2 tumors. All patients were treated surgically. Two patients had intralesional excisions, five patients had marginal excisions, and 17 patients had wide resections. With a mean followup of 17 years (range, 28 months-47 years), seven of 24 patients (29%) had one or more local recurrences. The 5-year local recurrence-free survival was less in patients treated with intralesional or marginal excisions (25%) than for patients treated with wide resections (93%). At the latest followup, six of 24 patients (25%) had died of pulmonary metastases. The overall 5-year metastasis-free survival was 83%. The 5-year metastasis-free survival was less for patients with Grade 2 tumors (50%) than for patients with Grade 1 tumors (94%). LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series no, or historical control group). See the Guidelines for Authors for a complete description of levels of evidence.

Radiologic case study. Gouty tophus involving the distal quadriceps tendon.

This case depicts an unusual presentation of gout, which could be mistaken for sarcoma. The radiographic and MRI findings suggest gout whereas the CT appearance is most specific. Therefore, CT should be considered when MRI demonstrates low to intermediate T2 signal in a heterogeneously enhancing soft-tissue mass around a joint, tendon, or bursa, especially when radiographs show adjacent erosion with a sclerotic margin. Gouty tophus is not excluded by a normal serum uric acid level. Computed tomography or ultrasound can be used to guide needle biopsy to provide diagnostic tissue.