Retrospective evaluation of MRI findings in arthroscopically confirmed cases of hypermobile lateral meniscus.

OBJECTIVE: To identify preoperative MRI findings in patients with arthroscopically confirmed hypermobile lateral meniscus utilizing a standard MRI knee protocol, with comparison to normal control and lateral meniscal tear groups. SUBJECTS AND METHODS: All patients with arthroscopically confirmed hypermobile lateral meniscus diagnosed at our institution were retrospectively identified. The following structures were evaluated on preoperative knee MRIs: superior and inferior popliteomeniscal fascicles, lateral meniscus and meniscocapsular junction, popliteal hiatus, and soft tissue edema around the popliteal hiatus. The same MRI features were evaluated in the normal control and lateral meniscal tear groups. RESULTS: Study, normal control, and lateral meniscal tear patients (18 each) were included. In the study group, 94.4% had superior popliteomeniscal fascicle abnormality, 89.0% had inferior popliteomeniscal fascicle abnormality, and 72.2% had lateral meniscal abnormality. Incidence of these abnormalities was significantly higher than in the normal control group. Meniscal abnormalities in the study group all involved the posterior horn meniscocapsular junction, 12/13 of which had vertical signal abnormality at the junction and 1/13 with anterior subluxation of the entire posterior horn. Popliteus hiatus measurements were largest in the lateral meniscal tear group. CONCLUSION: In patients with hypermobile lateral meniscus, the combination of popliteomeniscal fascicle abnormality and vertical signal abnormality at the meniscocapsular junction was seen in the majority of patients. Popliteomeniscal fascicle signal abnormality without identifiable lateral meniscal injury was the next most common imaging appearance. Radiologists may provide valuable information by suggesting the diagnosis of hypermobile lateral meniscus in such cases.

Multimodality evaluation of transfascial muscle and other soft tissue herniations of the extremities.

This review illustrates the multimodality assessment of transfascial muscle and other soft tissue herniations of the extremities. Transfascial herniations of the extremities can develop from congenital or acquired disruptions of the deep fascia, resulting in herniation of the underlying muscle, nerve, or soft tissue tumor into the subcutaneous tissues. While most patients present with a painless subcutaneous nodule that may change in size with muscle activation, some may experience focal or diffuse extremity symptoms such as pain and paresthesias. Although the diagnosis may be clinically suspected, radiologic evaluation is useful for definitive diagnosis and characterization. Ultrasound is the preferred modality for initial workup through a focused and dynamic examination. Magnetic resonance imaging can be utilized for equivocal, complicated, and preoperative cases. Computed tomography is less useful in the evaluation of transfascial herniations in the extremities due to similarities in the attenuation between muscle and fascia, which can decrease the conspicuity of small defects.

Traumatic rupture of the midportion of the interosseous membrane: a rare cause of acute lower leg pain in two soccer players kicked in the anterior shin.

The interosseous membrane (IOM) of the leg is a component of the tibiofibular syndesmosis that serves an important role in stabilization, as well as transferring forces to the fibula during weight-bearing. We present two separate cases of acute traumatic rupture of the midportion of the interosseous membrane in high school soccer players with blunt trauma to the anterior shin with MRI and ultrasound confirmation.

Medial patellofemoral ligament MRI abnormalities in the setting of MCL injuries: are they clinically relevant?

OBJECTIVE: To assess MRI abnormalities of the medial patellofemoral ligament (MPFL) in patients with clinically and MRI-proven superficial medial collateral ligament (sMCL) injuries and determine the clinical significance. MATERIALS AND METHODS: High-field strength knee MRI examinations were selected which demonstrated sMCL injuries. These cases were retrospectively reviewed for the presence, location, and severity of MPFL abnormality. The MPFL was divided into a more superior transverse component arising from a femoral attachment (tMPFL), and a broader more inferior oblique decussation component (odMPFL) arising from the anterior margin of the upper sMCL. Chart review was performed to determine the clinical relevance of any MPFL findings. RESULTS: One hundred patients with MCL injury were identified. These included 37 grade I sprains, 33 partial tears, 20 high-grade partial tears, and 10 full thickness tears. Abnormal edema was present at the femoral attachment of the tMPFL in 83%. The odMPFL was abnormal in 90%, most commonly involving the femoral third. No patients had imaging evidence of concurrent lateral patellar dislocation on the initial MRI study. No patients had documented patellofemoral instability at the time of original injury or upon follow-up. No patients required MPFL reconstruction. CONCLUSION: The MRI appearance of the MPFL is abnormal in the majority of patients with clinically and MRI-documented sMCL sprains and tears. These cases had no evidence of concurrent lateral patellar dislocation on the initial MRI and did not develop patellar instability symptoms.

Utility of the FABS MRI sequence in the evaluation of distal biceps pathology.

OBJECTIVE: The flexed elbow, abducted shoulder, forearm supinated (FABS) position has been described as a method of imaging the distal biceps tendon on its long axis. The purpose of this study is to evaluate whether obtaining additional MR imaging in the FABS position changes the radiologist's assessment of the distal biceps tendon compared with traditional sequences only. MATERIALS AND METHODS: Blinded review of 46 elbow MRIs when viewed without (-F) and with (+F) FABS sequences available was performed by two independent readers. The biceps tendon was graded in each case using a 0-3 scale, and a confidence level of 0-10 was assigned. -F and +F reads were compared. Reads were also compared with the surgical reference standard when available, 12 patients. RESULTS: Pooled intra rater reliability was 0.800 (0.714, 0.886) between the -F and +F groups. Pooled mean confidence was 7.163 (1.252) for the -F group and 8.370 (1.264) for the +F group (p < 0.001). Pooled diagnostic accuracy was 0.651 (0.420, 0.882) for the -F group and 0.615 (0.456, 0.875) for the +F group compared with the surgical reference standard. CONCLUSION: The FABS sequence changed the radiologist's impression of the distal biceps tendon in the minority of cases and did not significantly change diagnostic accuracy. We do not recommend its use in the majority of cases. In challenging cases of high-grade partial vs complete tendon tear, FABS may be helpful to identify subtle residual tendon fibers.

Osteochondral lesions of the lateral trochlear ridge: a rare, subtle but important finding on advanced imaging in patients with elbow pain.

OBJECTIVE: To characterize the radiographic, CT, and MRI appearance of clinically and/or surgically proven osteochondral lesions of the lateral trochlear ridge. MATERIALS AND METHODS: Ten years of medical charts with elbow radiographic, CT, and MRI studies were retrospectively reviewed. Patients with pathology isolated to the lateral trochlear ridge were included. Studies were reviewed by two radiologists. Identifiable pathology on each type of study was noted and characterized. RESULTS: Ten elbow studies were included, all from males aged 15 to 58 years (mean 29 years). Five elbow radiographs were normal, one showed mixed lucency and sclerosis of the lateral trochlear ridge, and four demonstrated small osseous fragments adjacent to the ridge. In all cases, CT demonstrated focal lucency at the cortical surface of the lateral trochlear ridge; 8 contained small osseous fragments, axial plane maximum width ranged from 5 to11 mm, depth from 1 to 2 mm. Focal bone marrow edema in the subchondral lateral trochlear ridge was found in the 6 cases with MR images. Two demonstrated linear high signal underlying the in situ osseous fragment, faintly visible on MRI. In 9 cases, arthroscopy was performed within 3 months of imaging. The remaining patient was treated conservatively with casting. CONCLUSIONS: Osteochondral lesions of the lateral trochlear ridge are rare but important, as these patients go on to arthroscopy at a high rate. If an abnormality of the lateral trochlear ridge is seen or suspected, we recommend CT as the best imaging study to define these lesions.

MRI appearance of jogger's foot.

OBJECTIVE: To characterize the MRI findings present in patients with clinically proven or suspected jogger's foot. MATERIALS AND METHODS: Ten years of medical charts in patients clinically suspected of having jogger's foot and who had MRI studies completed were identified utilizing a computer database search. Six study cases were identified. The MRI examinations of the study cases and an age- and gender-matched control group were reviewed in a blinded fashion by two musculoskeletal radiologists. Size and signal intensity of the medial plantar nerve were measured and characterized. The medial foot musculature was assessed for acute or chronic denervation changes. RESULTS: The medial plantar nerve was found to have moderately increased T2 signal compared with normal skeletal muscle in 3/6 study group cases and markedly increased T2 signal in the remaining 3/6 cases. In all control cases, the nerve was reported to have T2 signal equal or minimally higher than normal skeletal muscle. The mean total size of the medial plantar nerve was significantly larger in the study group when compared with that in the control group at all measured locations (p < 0.04). CONCLUSIONS: Abnormal thickness and T2 hyperintensity of the medial plantar nerve centered at the master knot of Henry are characteristic MRI findings in patients with jogger's foot when compared with control subjects. Muscular denervation changes may also be seen, most commonly in the flexor hallucis brevis muscle.

MRI appearance of the anomalous volar radiotriquetral ligament in true Madelung deformity.

OBJECTIVE: To characterize the MRI appearance of the anomalous volar radiotriquetral ligament in cases of classic Madelung deformity. MATERIALS AND METHODS: With institutional review board approval, a search of the radiology information system was performed to identify cases of potential Madelung deformity using variations of the criteria "Madelung deformity." Cases of classic Madelung deformity were included based on the following criteria: dorsal subluxation of the ulnar head, volar tilt of the distal radius, increased radial inclination of greater than 25°, triangulation of the carpus, and presence of Vickers ligament defined as an anomalous volar radiolunate ligament. Patients with a history of wrist trauma or severe degenerative change distorting anatomy were excluded. The resulting cases were reviewed to characterize the anomalous radiotriquetral ligament. RESULTS: Eight cases of classic Madelung deformity in 6 patients were identified. All 8 cases were characterized by the presence of an anomalous radiotriquetral ligament, which was more conspicuous than Vickers ligament. None of the excluded pseudo-Madelung deformity cases displayed a Vickers ligament or radiotriquetral ligament. CONCLUSION: The radiotriquetral ligament is an anomalous ligament that is a constant and distinguishing finding in classic Madelung deformity in this study. Awareness of the radiotriquetral ligament and distinguishing it from Vickers ligament on imaging studies and at surgery may have clinical implications that need to be further investigated.

Stem Cells Combined With Platelet-rich Plasma Effectively Treat Corticosteroid-induced Osteonecrosis of the Hip: A Prospective Study.

BACKGROUND: Randomized trials have shown the benefits of injecting bone marrow-derived mesenchymal stem cells (BmMSCs) after standard hip decompression in patients with osteonecrosis of the femoral head. However, the combination of BmMSCs and platelet-rich plasma (PRP) injected into the femoral head after decompression has not been reported previously. This study reports the results in a preliminary series of patients with osteonecrosis of the femoral head treated with BmMSCs plus PRP. QUESTIONS/PURPOSES: (1) What is the survivorship free from reoperation, hip arthroplasty, and femoral head collapse in a preliminary series of patients with osteonecrosis of the femoral head treated with BmMSCs plus PRP? (2) Is there a change in the degree of femoral head involvement based on modified Kerboul angle? (3) What were the scores observed for pain and function at last followup? (4) Was there a difference in survivorship free from reoperation as a function of in vitro MSC count and viability? METHODS: Twenty-two consecutive patients (35 hips; 11 men and 11 women) with corticosteroid-induced osteonecrosis who met study inclusion criteria were enrolled; none declined participation, and none was lost to followup, although one patient (two hips) died within a year of the procedure for reasons unrelated to it, and five patients (seven hips) did not undergo MRI at the 1-year followup. All patients had precollapse osteonecrosis, rated either University of Pennsylvania Stage 1 (n = 4) or Stage 2 (n = 31 hips). Mean age and body mass index were 43 years and 31 kg/m, respectively. Patients underwent pre- and postoperative radiographs and MRI to assess femoral head involvement using the modified Kerboul angle. Absolute cell count and colony-forming unit (CFU) assays were used to assess MSC abundance and viability of the bone marrow obtained at the time of surgery. Patients were followed at regular intervals to assess clinical response to treatment with a mean followup of 3 years (range, 2-4 years). The change in femoral head involvement was assessed with the modified Kerboul angle; the Harris hip score was used to assess clinical outcome; and conversion to THA, reoperation, and survivorship free from femoral head collapse were analyzed with the Kaplan-Meier method on a per-hip basis. RESULTS: Survivorship free from THA, any procedure, and femoral head collapse was 84% (95% confidence interval [CI], 75%-93%), 67% (95% CI, 55%-79%), and 93% (95% CI, 76%-98%), respectively, at 3 years postoperatively; two patients (four hips) underwent a second decompression and MSC injection for persistent pain without signs of radiographic collapse. All patients with collapse underwent THA. The mean modified Kerboul angle improved from 205° ± 47° to 172° ± 48° postoperatively (mean change -30° ± 6°, p = 0.01). A greater proportion of patients who underwent an additional procedure had a modified Kerboul grade of 3 or 4 preoperatively (80% [four of five] versus 13% [four of 30 Grade 1 or 2; odds ratio, 26; 95% CI, 2-296; p = 0.005). Preoperatively the mean Harris hip score was 57 ± 12, which improved to 85 ± 15 (mean change 28 ± 3, p < 0.001) at most recent followup. Patients undergoing a reoperation or THA had a lower mean concentration of nucleated cells/mL (5.5 x 10 ± 2.8 x 10 cells/mL versus 2.3 x 10 ± 2.2 x 10 cells/mL, p = 0.02) and lower mean CFUs (13 ± 6 versus 19 ± 7, p = 0.04) compared with those who did not. CONCLUSIONS: Core hip decompression with injection of concentrated bone marrow plus PRP improved pain and function; > 90% of hips in this series were without collapse at a minimum of 2 years. In this preliminary study, successful results were seen when nucleated cell count was high and modified Kerboul grade was low. Further randomized studies are needed to determine this procedure's efficacy versus core decompression or nonoperative treatment alone. LEVEL OF EVIDENCE: Level II, therapeutic study.

MR arthrogram of the postoperative glenoid labrum: normal postoperative appearance versus recurrent tears.

OBJECTIVE: The purpose of this study is to describe the MR arthrogram appearance of the postoperative glenoid labrum and to describe the features consistent with recurrent tear. MATERIALS AND METHODS: We identified 30 patients who had undergone glenoid labral repair, had a subsequent MR arthrogram of his or her shoulder, and went on to repeat shoulder arthroscopy. Each MR arthrogram was reviewed blindly, and the glenoid labrum was described as normal, irregular, or torn. Additional findings recorded included the presence or absence of a paralabral cyst and suture anchors in the glenoid. The operative report was also reviewed for each patient to determine the status of the labrum at arthroscopy. RESULTS: Following consensus review, 18/30 MRIs were felt to demonstrate recurrent glenoid labral tear, 11/30 showed an irregular labrum, and 1/30 was called normal. The radiology impression regarding the presence or absence of a recurrent glenoid labral tear agreed with the operative report in 24/30 (80%) cases, and was discrepant in six. This equals 83.3% sensitivity and 81.8% specificity of MR arthrogram in the diagnosis of recurrent labral tear in this study. A paralabral cyst was present in 3/30 (10%) cases, all three of which were torn. CONCLUSIONS: MR arthrogram findings of signal equal to gadolinium or fluid within or underlying the glenoid labrum and markedly diminutive or absent labrum were the most useful features to diagnose recurrent tear. Some signal underlying the labrum, which is confined to the anterosuperior quadrant, may be normal. The secondary finding of a paralabral cyst was also highly sensitive for recurrent tear.

CT characteristics of Morel-Lavallée lesions: an under-recognized but significant finding in acute trauma imaging.

OBJECTIVE: To highlight the significance and imaging characteristics of Morel-Lavallée (ML) lesions, which have been well characterized on MRI, but are potentially under-recognized on CT. MATERIALS AND METHODS: Twenty-eight Morel-Lavallée lesions were identified in 18 patients and were all clinically or surgically confirmed. Lesions were grouped into acute (<3 days), subacute (3-30 days), and chronic (>30 days) at the time of CT imaging. Charts were reviewed to gather patient characteristics, injury patterns, radiologist interpretation, treatment, and outcomes. RESULTS: Sixteen male and 2 female patients with a mean age of 50 years (range 19-80) at the date of their initial evaluation were identified. All patients had significant trauma that accounted for 28 ML lesions, all of which were in a characteristic subcutaneous location overlying the muscular fascial plane. Lesions on CT went through an evolution from hyperdense, poorly or moderately marginated without a pseudocapsule to being hypodense, with internal fat globules or septations and well marginated with a complete enhancing pseudocapsule. Only 1 (4 %) of the ML lesions was suggested and 7 (25 %) lesions were not commented on at all by the interpreting radiologist. CONCLUSION: Morel-Lavallée lesions are post-traumatic closed, internal, soft-tissue, degloving lesions that are potentially underrecognized on CT. Most acute ML lesions are nonspecific, resembling simple hematomas or contusions. ML lesions evolve as they age with subacute and chronic lesions demonstrating the known features described on MR imaging that should allow for an accurate imaging diagnosis.

Intra-articular pathology associated with isolated posterior cruciate ligament injury on MRI.

OBJECTIVE: Unlike with anterior cruciate ligament injury, little is known about the prevalence of intra-articular pathology associated with isolated posterior cruciate ligament (PCL) injury in the knee. The objectives of this study were to characterize and identify the frequency of meniscal tears and osteochondral injuries in these patients, and to see if management might be affected. MATERIALS AND METHODS: Altogether, 48 knee MRI exams with isolated PCL tears were evaluated for the presence of: grade and location of PCL tear, meniscal tear, articular chondral lesion, bone bruise, and fracture. Comparisons between PCL tear grade and location, as well as mechanism of injury when known, with the presence of various intra-articular pathologies, were made using the chi-square or Fisher's exact test as appropriate. RESULTS: In all, 69 % of isolated PCL tears occur in the midsubstance, 27 % proximally. Meniscal tears were seen in 25 % of knees, involving all segments of both menisci, except for the anterior horn medial meniscus. Altogether, 23 % had focal cartilage lesions, usually affecting the central third medial femoral condyle and medial trochlea, while 12.5 % of knees had fractures, and 48 % demonstrated bone bruises, usually involving the central to anterior tibiofemoral joint. The presence of a fracture (p = 0.0123) and proximal location of PCL tear (p = 0.0016) were both associated with the hyperextension mechanism of injury. There were no statistically significant associations between PCL tear grade and presence of intra-articular abnormality. CONCLUSION: Potentially treatable meniscal tears and osteochondral injuries are relatively prevalent, and demonstrable on MRI in patients with isolated acute PCL injury of the knee.

The adductor magnus "mini-hamstring": MRI appearance and potential pitfalls.

OBJECTIVE: To examine the anatomic MRI characteristics of the adductor magnus mini hamstring (AMMH) and explore its involvement in cases of hamstring avulsion. MATERIALS AND METHODS: An IRB-approved retrospective review of patients undergoing "hamstring protocol" MRI between March 2009 and June 2014 was performed. Two musculoskeletal radiologists recorded multiple AMMH anatomic characteristics and involvement in cases of hamstring avulsion. RESULTS: Seventy-six AMMHs were analyzed in 66 patients [35 females and 31 males, mean age 49.3 ± 15.2 years (range 17-81)]. Eleven percent of AMMHs were poorly visualized, 51 % visualized, and 37 % well visualized. Seven percent demonstrated round, 73 % ovoid, and 21 % flat/lenticular tendon morphologies. Most (88 %) demonstrated typical origins. Average cross-sectional area (CSA) was 22.4 ± 10.6 mm² (range 6-56), diameter was 7.2 ± 2.5 mm (range 2.9-15), medial distance from the semimembranosus tendon was 7.5 ± 2.5 mm (range 3-14), and tendon length was 6.8 ± 3.3 cm (range 1.2-14.1). There was no gender difference in AMMH anatomic measurements or correlation between age and CSA or diameter. Of 17 complete hamstring avulsion cases, the AMMH was intact in 13, partially torn in 3, and completely torn in 1. CONCLUSION: The AMMH is a constant finding with variable anatomic characteristics. It is visualized or well visualized by MRI in 88 % of cases and is a sizable tendon located in close proximity to the semimembranosus tendon. Because it is uncommonly completely torn (6 %) in cases of complete hamstring avulsion, radiologists should be aware of its presence and appearance to avoid diagnostic confusion.

Sequential imaging of intraneural sciatic nerve endometriosis provides insight into symptoms of cyclical sciatica.

Endometriosis of the nerve often remains an elusive diagnosis. We report the first case of intraneural lumbosacral plexus endometriosis with sequential imaging at different phases of the menstrual cycle: during the luteal phase and menstruation. Compared to the first examination, the examination performed during the patient's period revealed the lumbosacral plexus larger and hyperintense on T2-weighted imaging. The intraneural endometriosis cyst was also larger and showed recent hemorrhage. Additionally, this case represents another example of perineural spread of endometriosis from the uterus to the lumbosacral plexus along the autonomic nerves and then distally to the sciatic nerve and proximally to the spinal nerves.

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.

MRI injury patterns in surgically confirmed and reconstructed posterolateral corner knee injuries.

PURPOSE: The posterolateral corner (PLC) of the knee is anatomically complex with similarly complex MR imaging findings in acutely injured knees. The purpose of this study was to define the MRI pattern of injury in cases of PLC disruption requiring surgery because of clinical instability. METHODS: The knee MRIs of 22 patients who underwent surgical repair and/or reconstruction of PLC injury were retrospectively reviewed. The fibular collateral ligament (FCL), popliteus tendon (PT), biceps femoris (BF), popliteofibular ligament (PFL), arcuate ligament (AL), and fabellofibular ligament (FFL) were evaluated and graded as follows: complete tear, high-grade partial tear, low-grade partial tear, and normal. RESULTS: In the 22 cases of PLC injury that necessitated surgery, a constellation of findings involving the larger structures of the PLC was identified. Of the FCL, PT, and BF (considered larger structures), at least two were abnormal in all 22 injury cases. Of the PFL, AL, and FFL (considered smaller structures), the PFL appeared abnormal in 19 cases, yet neither the AL nor FFL were confidently characterized in the injury group. CONCLUSION: The larger structures of the PLC are easily evaluated using standard MRI techniques. This study identified a predictable pattern of imaging findings involving these more easily assessed structures in those patients who were felt to be clinically unstable and underwent surgical reconstruction, as at least two were abnormal in all 22 cases. The smaller structures of the PLC are difficult to assess with MRI; however, direct visualization of their involvement on MRI is not necessary to report a clinically unstable PLC injury. Emphasis of this simplified but critical analysis of the FCL, BF and PT on MRI scans reviewed by radiologists and orthopaedic surgeons may help to prevent delayed diagnosis of unstable PLC injuries. LEVEL OF EVIDENCE: III.

Patellar calcar: MRI appearance of a previously undescribed anatomical entity.

OBJECTIVE: The femoral calcar is a constant anatomical structure within the proximal femur representing a condensation of bone trabeculae. It is our impression that a similar structure is present within the patella. The purpose of this retrospective study was to define the prevalence, appearance, location, and configuration of the patellar calcar on MRI examinations. MATERIALS AND METHODS: One hundred consecutive unenhanced knee MRIs were retrospectively reviewed by two readers who were blinded to the clinical indication. The patellar calcar was defined as a dark signaling, linear or curvilinear structure subjacent to the patellar articular surface. If present, the patellar calcar was assigned to a "well seen," "moderately well seen," or "faintly seen" category. Location of the calcar within the patella, orientation, configuration, and thickness were recorded. Confounding variables, such as marrow edema, patellar chondromalacia, bipartite patella, or postoperative changes were also recorded. RESULTS: The patellar calcar was visualized in 81 out of 100 (81 %) MRIs. When detected, the calcar was well seen in 20 out of 81 (25 %), moderately well seen in 35 out of 81 (43 %), and faintly seen in 26 out of 81 (32 %). The anteroposterior width of the calcar measured at its thickest segment was: < 1 mm in 43 out of 81 (53 %), 1 mm in 28 out of 81 (35 %), and >1 mm in 10 out of 81 (12 %). CONCLUSION: The patellar calcar was seen in the majority of knee MRIs and had a consistent imaging appearance. The calcar may be obscured by degenerative arthrosis of the patella and rarely may mimic patellar stress fracture or osteochondritis dissecans. Radiologists and clinicians should be familiar with this normal anatomical structure.

Utility of preoperative MRI for assessing proximal fragment vascularity in scaphoid nonunion.

Aims: The benefit of MRI in the preoperative assessment of scaphoid proximal fragment vascularity remains controversial. The purpose of this study is to compare preoperative MRI findings to intraoperative bleeding of the proximal scaphoid. Methods: A retrospective review of 102 patients who underwent surgery for scaphoid nonunion between January 2000 and December 2020 at a single institution were identified. Inclusion criteria were: isolated scaphoid nonunion; preoperative MRI assessing the proximal fragment vascularity; and operative details of the vascularity of the proximal fragment with the tourniquet deflated. MRI results and intraoperative findings were dichotomized as either 'yes' or 'no' for the presence of vascularity. A four-fold contingency table was used to analyze the utility of preoperative MRI with 95% confidence intervals. Relative risk was calculated for subgroups to analyze the association between variables and MRI accuracy. Results: Preoperative MRI identified 55 proximal scaphoid fragments with ischaemia and 47 with vascularized proximal fragments. After the proximal fragment was prepared, the tourniquet was deflated and assessed for bleeding; 63 proximal fragments had no bleeding and 39 demonstrated bleeding. MRI was not reliable or accurate in the assessment of proximal fragment vascularity when compared with intraoperative assessment of bleeding. No patient or MRI factors were identified to have a statistical impact on MRI accuracy. Conclusion: Current preoperative MRI protocols and diagnostic criteria do not provide a high degree of correlation with observed intraoperative assessment of proximal fragment bleeding. While preoperative MRI may assist in surgical planning, intraoperative assessment remains the best means for assessing proximal fragment vascularity in scaphoid nonunion. Future efforts should focus on the development of objective measures of osseous blood flow that may be performed intraoperatively.

Outcomes in patients with clinically suspected pedal osteomyelitis based on bone marrow signal pattern on MRI.

Objective: confluent T1 hypointense marrow signal is widely accepted to represent osteomyelitis on MRI. Some authors have suggested that non-confluent bone marrow signal abnormality should be considered early osteomyelitis. The purpose of this study was to address this issue by comparing the rate of osteomyelitis and amputation based on T1 marrow signal characteristics. Materials and methods: a total of 112 patients who underwent MRI of the foot for the evaluation of possible osteomyelitis were included. Patients were assigned to confluent T1 hypointense, reticulated T1 hypointense, and normal bone marrow signal groups. Results: patients with confluent T1 hypointense signal on MRI had significantly higher rates of osteomyelitis and amputation at 2 and 14 months post-MRI than the reticulated T1 hypointense group ( p < 0.001 ). Six patients had normal T1 signal, 16.7 % of whom had osteomyelitis and underwent amputation by 2 months post-MRI. Of 61 patients with reticulated T1 hypointense signal, 19.7 % had a diagnosis of osteomyelitis at 2 months post-MRI and 30.8 % had a diagnosis of osteomyelitis at 14 months post-MRI; moreover, 14.8 % and 31.5 % underwent amputation by 2 and 14 months post-MRI, respectively. Of 45 patients with confluent T1 hypointense signal, 73.3 % of patients had osteomyelitis at 2 months post-MRI and 82.5 % had osteomyelitis at 14 months post-MRI. In this group, 66.7 % underwent amputation by 2 months post-MRI and 77.8 % underwent amputation by 14 months post-MRI. Conclusions: over half of the patients with suspected pedal osteomyelitis who had reticulated or normal T1 bone marrow signal on MRI healed with conservative measures. Therefore, we recommend terminology such as "osteitis", "reactive osteitis", or "nonspecific reactive change" to describe bone marrow edema-like signal and reticulated hazy T1 hypointense signal without associated confluent T1 hypointensity. Moreover, we recommend that the MRI diagnosis of osteomyelitis is reserved for confluent T1 hypointense bone signal in the area of concern.