UTE bi-component analysis of T2* relaxation in articular cartilage.

OBJECTIVES: To determine T2* relaxation in articular cartilage using ultrashort echo time (UTE) imaging and bi-component analysis, with an emphasis on the deep radial and calcified cartilage. METHODS: Ten patellar samples were imaged using two-dimensional (2D) UTE and Car-Purcell-Meiboom-Gill (CPMG) sequences. UTE images were fitted with a bi-component model to calculate T2* and relative fractions. CPMG images were fitted with a single-component model to calculate T2. The high signal line above the subchondral bone was regarded as the deep radial and calcified cartilage. Depth and orientation dependence of T2*, fraction and T2 were analyzed with histopathology and polarized light microscopy (PLM), confirming normal regions of articular cartilage. An interleaved multi-echo UTE acquisition scheme was proposed for in vivo applications (n = 5). RESULTS: The short T2* values remained relatively constant across the cartilage depth while the long T2* values and long T2* fractions tended to increase from subchondral bone to the superficial cartilage. Long T2*s and T2s showed significant magic angle effect for all layers of cartilage from the medial to lateral facets, while the short T2* values and T2* fractions are insensitive to the magic angle effect. The deep radial and calcified cartilage showed a mean short T2* of 0.80 ± 0.05 ms and short T2* fraction of 39.93 ± 3.05% in vitro, and a mean short T2* of 0.93 ± 0.58 ms and short T2* fraction of 35.03 ± 4.09% in vivo. CONCLUSION: UTE bi-component analysis can characterize the short and long T2* values and fractions across the cartilage depth, including the deep radial and calcified cartilage. The short T2* values and T2* fractions are magic angle insensitive.

Dual inversion recovery ultrashort echo time (DIR-UTE) imaging and quantification of the zone of calcified cartilage (ZCC).

OBJECTIVE: To develop ultrashort echo time (UTE) magnetic resonance imaging (MRI) techniques to image the zone of calcified cartilage (ZCC), and quantify its T2*, T1 and T1ρ. DESIGN: In this feasibility study a dual inversion recovery UTE (DIR-UTE) sequence was developed for high contrast imaging of the ZCC. T2* of the ZCC was measured with DIR-UTE acquisitions at progressively increasing TEs. T1 of the ZCC was measured with saturation recovery UTE acquisitions at progressively increasing saturation recovery times. T1ρ of the ZCC was measured with spin-locking prepared DIR-UTE acquisitions at progressively increasing spin-locking times. RESULTS: The feasibility of the qualitative and quantitative DIR-UTE techniques was demonstrated on phantoms and in six cadaveric patellae using a clinical 3 T scanner. On average the ZCC has a short T2* ranging from 1.0 to 3.3 ms (mean ± standard deviation = 2.0 ± 1.2 ms), a short T1 ranging from 256 to 389 ms (mean ± standard deviation = 305 ± 45 ms), and a short T1ρ ranging from 2.2 to 4.6 ms (mean ± standard deviation = 3.6 ± 1.2 ms). CONCLUSION: UTE MR based techniques have been developed for high resolution imaging of the ZCC and quantitative evaluation of its T2*, T1 and T1ρ relaxation times, providing non-invasive assessment of collagen orientation and proteoglycan content at the ZCC and the bone cartilage interface. These measurements may be useful for non-invasive assessment of the ZCC, including understanding the involvement of this tissue component in osteoarthritis.

T1ρ and T2 mapping of the intervertebral disk: comparison of different methods of segmentation.

BACKGROUND AND PURPOSE: Intervertebral disk biochemical composition could be accessed in vivo by T1ρ and T2 relaxometry. We found no studies in the literature comparing different segmentation methods for data extraction using these techniques. Our aim was to compare different manual segmentation methods used to extract T1ρ and T2 relaxation times of intervertebral disks from MR imaging. Seven different methods of partial-disk segmentation techniques were compared with whole-disk segmentation as the reference standard. MATERIALS AND METHODS: Sagittal T1ρ and T2 maps were generated by using a 1.5T MR imaging scanner in 57 asymptomatic volunteers 20-40 years of age. Two hundred eighty-five lumbar disks were separated into 2 groups: nondegenerated disk (Pfirrmann I and II) and degenerated disk (Pfirrmann III and IV). In whole-disk segmentation, the disk was segmented in its entirety on all sections. Partial-disk segmentation methods included segmentation of the disk into 6, 5, 4, 3, and 1 sagittal sections. Circular ROIs positioned in the nucleus pulposus and annulus fibrosus were also used to extract T1ρ and T2, and data were compared with whole-disk segmentation RESULTS: In the nondegenerated group, segmentation of ≥5 sagittal sections showed no statistical difference with whole-disk segmentation. All the remaining partial-disk segmentation methods and circular ROIs showed different results from whole-disk segmentation (P < .001). In the degenerated disk group, all methods were statistically similar to whole-disk segmentation. All partial-segmentation methods, including circular ROIs, showed strong linear correlation with whole-disk segmentation in both the degenerated and nondegenerated disk groups. CONCLUSIONS: Manual segmentation showed strong reproducibility for T1ρ and T2 and strong linear correlation between partial- and whole-disk segmentation. Absolute T1ρ and T2 values extracted from different segmentation techniques were statistically different in disks with Pfirrmann grades I and II.

Effects of microgravity on the composition of the intervertebral disk.

The lumbar annuli of rats flown on COSMOS 2044 were compared with those of three control groups and a tail-suspension experimental model. The wet and dry weights of the annuli were significantly smaller (P less than 0.05) in the flight group than in three control groups. The collagen-to-proteoglycan ratio was significantly greater (P less than 0.001) in the flight group than in the three control groups, but there were no detectable changes in the relative proportions of type I and II collagen or in the number of pyridinoline cross-links. When the annuli were immersed in water for 2 h, more proteoglycans (P less than 0.001) leached from the annuli of flown rats than from the tissue of control animals, suggesting abnormal or smaller proteoglycans. Safranin-O indicated a normal spatial distribution of the proteoglycans within the annulus. Tail suspension did not affect the size of the annuli, but more proteoglycans (P less than 0.05) leached from the tissue of suspended animals than from the normal annuli. The reasons for smaller disks and the abnormal ratio between the fibrous collagenous network and the proteoglycan gel in the flight group are unknown at this time. It is, however, probable that these changes may affect the biomechanical functions of the annulus, although they may be temporary and totally reversible if injuries are avoided in the interim period.

Stimulation of dorsal root ganglia and degradation of rabbit annulus fibrosus.

The authors sought to determine whether narrowing of the intervertebral neural foramen, by itself and in association with vibration, would stimulate the mechanosensitive dorsal root ganglia and result in degradation of proteoglycan and collagen of the annulus fibrosus, as proposed in their working model of dorsal root ganglia-neuropeptide-mediated degeneration of the spinal motion segment. Degradation of proteoglycan and collagen of rabbit annulus was observed when there was narrowing of the neural foremen and the degradation process was accelerated by vibration. Vibration alone, in the absence of structural abnormalities of the spinal motion segment, did not induce matrix degradation probably because of a less pronounced stimulation of the dorsal root ganglia. Biological events similar to those postulated here, fomented by a combination of structural abnormalities and environmental factors, could be involved in human disc degeneration.

Radiography of cervical spine injury in children: are flexion-extension radiographs useful for acute trauma?

OBJECTIVE: We assessed the role of cervical spine flexion-extension radiographs in the acute evaluation of pediatric trauma patients. MATERIAL AND METHODS: We performed a retrospective review of all pediatric trauma patients who underwent static cervical spine radiography followed by flexion-extension radiography during a 22-month period. We reviewed the mechanism of injury, physical examination findings, and patient age, and tabulated the results of initial and follow-up imaging studies. RESULTS: Two hundred forty seven children (age range, 1.6-18 years; mean age, 11.5 years) with a history of trauma underwent cervical spine radiography followed by flexion-extension radiography. Static cervical spine radiographs revealed normal findings in 224 patients (91%). Flexion-extension radiographs revealed normal findings for all patients with normal findings on cervical spine radiographs. Of 23 children (9%) with abnormal findings on static cervical spine radiographs, seven (30%) had congenital abnormalities visible on flexion-extension radiographs; 10 (43%) had traumatic injuries including fracture, subluxation, or soft-tissue swelling; two (9%) had instability; and six (26%) had questionable abnormalities that were noted on static cervical spine radiographs. In four patients (66%) with abnormal findings on static cervical spine radiographs, flexion-extension radiographs were helpful in ruling out abnormality. CONCLUSION: In children with a history of trauma and normal findings on static cervical spine radiographs, additional flexion-extension radiographs are of questionable use.

Magnetic resonance imaging of the upper extremity: advances in technique and application.

Vast advances in technology have taken place in the field of radiology led by the introduction of magnetic resonance imaging. The added advantages of exquisite soft tissue contrast and multiplanar imaging capabilities have revolutionized the understanding of complex anatomic relationships and diagnoses. The current authors will focus on the introduction of new advances in magnetic resonance imaging of the upper extremity that may prove helpful in the diagnosis and treatment of upper extremity abnormalities.

Cartilage imaging techniques: current clinical applications and state of the art imaging.

The high incidence of cartilage lesions, coupled with the recent advances for their surgical and nonsurgical treatment, have necessitated the development of techniques for accurate diagnosis and monitoring of these lesions. Although arthroscopy has been the standard for cartilage evaluation, magnetic resonance imaging has emerged as the imaging method of choice, allowing analysis of its infrastructure and surface abnormalities. The authors will focus on current clinical applications for articular cartilage analysis and advances and the future direction of the imaging of articular cartilage.

Greater trochanter of the hip: attachment of the abductor mechanism and a complex of three bursae--MR imaging and MR bursography in cadavers and MR imaging in asymptomatic volunteers.

PURPOSE: To evaluate trochanteric anatomy with magnetic resonance (MR) imaging, bursography, MR bursography, and anatomic analysis. MATERIALS AND METHODS: T1-weighted and fat-saturated T2-weighted (transverse, sagittal, coronal, and coronal oblique planes) MR imaging of the greater trochanter was performed in 10 cadaveric hips and 12 hips of asymptomatic volunteers. Three bursae comprising the trochanteric bursa complex were injected, and conventional radiography and MR imaging were performed. The specimens were sectioned for anatomic analysis, corresponding to the MR imaging planes. Tendon attachments and bursal localization were related to the facets of the greater trochanter. RESULTS: The bony surface of the greater trochanter consists of four facets: anterior, lateral, posterior, and superoposterior. The gluteus medius muscle attaches to the superoposterior and lateral facets. The gluteus minimus muscle attaches to the anterior facet. The trochanteric bursa covered the posterior facet and the lateral insertion of the gluteus medius muscle. The subgluteus medius bursa was located in the superior part of the lateral facet, underneath the gluteus medius tendon. The subgluteus minimus bursa lies in the area of the anterior facet, underneath the gluteus minimus tendon, medial and cranial to its insertion, and extends medially covering the distal anterior part of the hip joint capsule. The trochanteric bursa is delineated with fat on both sides and can be seen on transverse nonenhanced T1-weighted images as a fine line curving around the posterior part of the trochanter. CONCLUSION: MR imaging and bursography provide detailed information about the anatomy of tendinous attachments of the abductor muscles and the bursal complex of the greater trochanter.

Patellar tendon-lateral femoral condyle friction syndrome: MR imaging in 42 patients.

OBJECTIVE: To demonstrate the MR imaging findings that occur between the posterior inferolateral patellar tendon and the lateral femoral condyle in patients with chronic anterior and or lateral knee pain. PATIENTS AND DESIGN: A retrospective review of the MR images in 42 patients who presented with chronic anterior or lateral knee pain was performed by two musculoskeletal radiologists. In 15 patients, post-contrast images were available. RESULTS: Sagittal and axial imaging planes best demonstrated the patellar tendon and its relationship with the lateral femoral condyle. In 40 patients, there was obliteration of the fat planes and abnormal signal intensity in the lateral soft tissues of the inferior patellofemoral joint. Enhancement after administration of gadolinium was noted in all cases in which contrast was administered. Eighteen patients showed cystic changes in the soft tissues adjacent to the lateral femoral condyle in addition to fat plane obliteration. In two patients, only cystic changes were noted in the lateral soft tissues. Abnormal patellar alignment was noted in 37 patients. Patellar tendon pathology was seen in nine patients. CONCLUSION: In evaluating anterior knee symptoms, MR imaging allows identification of changes that may be related to patellar tendon-lateral femoral condyle friction syndrome and that should be distinguished from other causes of anterior or lateral knee pain.

Intramedullary osteosclerosis: imaging features in nine patients.

PURPOSE: To determine the conventional radiographic, computed tomographic (CT), magnetic resonance (MR) imaging, scintigraphic, and histologic features of intramedullary osteosclerosis and to review the clinical features. MATERIALS AND METHODS: Nine female patients with leg pain and imaging features indicative of intramedullary sclerosis were seen during a 25-year period. None of the patients had a history of trauma or infection, familial bone disease, or related abnormal laboratory findings. Imaging studies included radiography (n = 9), CT (n = 4), MR imaging (n = 5), and skeletal scintigraphy (n = 5). Histologic correlation was available in five patients. RESULTS: Sixteen bone lesions (midtibia, n = 14; distal fibula, n = 1; and proximal femur, n = 1) were evident. Both lower extremities were involved in seven patients, and a single extremity was involved in two. Intramedullary sclerosis was present, as was cortical thickening, mainly in the diaphysis of the long bones, without extensive periosteal reaction or soft-tissue involvement. Findings at bone scintigraphy were positive in all lesions. Histologic analysis showed nonspecific changes of markedly sclerotic bone with a variable degree of mineralization and maturity. CONCLUSION: Intramedullary osteosclerosis is a distinct disorder that typically affects the diaphysis of one or both tibiae in women. Characteristic imaging findings, when coupled with clinical information, allow precise diagnosis.

MR arthrography of the glenohumeral joint: a tailored approach.

OBJECTIVE: The purpose of this study was to anatomically confirm that anterior shoulder injection could result in penetration of the anterior stabilizing structures of the glenohumeral joint and to advocate the use of a tailored approach to MR arthrography based on presenting symptoms. CONCLUSION: A tailored approach to MR arthrography may be a useful way to isolate expected pathology in the shoulder and limit confounding findings related to the performance of the procedure.

Characterization of the "red zone" of knee meniscus: MR imaging and histologic correlation.

PURPOSE: To determine the extent and vascularity of knee menisci with conventional and gadolinium-enhanced magnetic resonance (MR) imaging in cadaveric specimens, with histologic findings as the reference standard, and to investigate signal intensity changes in menisci and perimeniscal soft tissues in symptomatic patients. MATERIALS AND METHODS: Radial dimensions and enhancement patterns of menisci were recorded and compared in (a) 12 cadaveric menisci examined with conventional and gadolinium-enhanced intermediate-weighted and fat-suppressed T1-weighted spin-echo MR imaging, high-spatial-resolution T1-weighted and fast low-angle shot MR imaging, and gross anatomic and histologic specimens and (b) 18 patients examined with conventional and gadolinium-enhanced fat-suppressed T1-weighted spin-echo MR imaging. RESULTS: No differences in radial measurements of the meniscus were found for different MR techniques (P =.551). Despite the presence of vessels in the peripheral 10%-15% of the menisci, no enhancement of menisci was detected in specimens or patients. Perimeniscal soft-tissue enhancement adjacent to the posterior horn was greater than that adjacent to the anterior horn (P <.05), and enhancement of the lateral meniscal body was greater than that of the medial meniscal body (P <.05). CONCLUSION: The wedge-shaped low-signal-intensity structure seen on MR images represents the entire meniscus. Intravenous injection of contrast material does not appear to be useful for differentiation of the vascularized from the nonvascularized zone of the meniscus.

Pulley system in the fingers: normal anatomy and simulated lesions in cadavers at MR imaging, CT, and US with and without contrast material distention of the tendon sheath.

PURPOSE: To describe the normal anatomy of the finger flexor tendon pulley system, with anatomic correlation, and to define criteria to diagnose pulley abnormalities with different imaging modalities. MATERIALS AND METHODS: Three groups of cadaveric fingers underwent computed tomography (CT), magnetic resonance (MR) imaging, and ultrasonography (US). The normal anatomy of the pulley system was studied at extension and flexion without and with MR tenography. Pulley lengths were measured, and anatomic correlation was performed. Pulley lesions were created and studied at flexion, extension, and forced flexion. Two radiologists reviewed the studies in blinded fashion. RESULTS: MR imaging demonstrated A2 (proximal phalanx) and A4 (middle phalanx) pulleys in 12 (100%) of 12 cases, without and with tenography. MR tenography showed the A3 (proximal interphalangeal) and A5 (distal interphalangeal) pulleys in 10 (83%) and nine (75%) cases, respectively. US showed the A2 pulley in all cases and the A4 pulley in eight (67%). CT did not allow direct pulley visualization. No significant differences in pulley lengths were measured at MR, US, or pathologic examination (P: =.512). Direct lesion diagnosis was possible with MR imaging and US in 79%-100% of cases, depending on lesion type. Indirect diagnosis was successful with all methods with forced flexion. CONCLUSION: MR imaging and US provide means of direct finger pulley system evaluation.

Rotator cuff interval: evaluation with MR imaging and MR arthrography of the shoulder in 32 cadavers.

PURPOSE: The purpose of this work was to establish the optimal means of evaluation of the rotator cuff interval (RCI) and rotator interval capsule and demonstrate normal anatomy of the RCI using MR imaging and MR arthrography. METHOD: MR arthrography was performed in 32 cadaveric shoulders. In 20 cases, MR imaging was completed prior to arthrography. Pre- and postarthrography studies included standard imaging planes. Images were evaluated by the consensus of two musculoskeletal radiologists with attention to the RCI, rotator interval capsule (measurements on postarthrographic studies), and crossing structures. In five cases, specialized imaging planes were performed after arthrography. RESULTS: The RCI, rotator interval capsule, and crossing structures were best evaluated by MR arthrography. The anteroposterior dimension of the rotator interval capsule could be best depicted on postarthrogram images. CONCLUSION: MR arthrography, with both standard and specialized imaging planes, is a useful way to evaluate the RCI, the rotator interval capsule, and its crossing structures.

The changes of ocular axial length and corneal curvatures after scleral buckling for retinal detachment.

As myopia plays an important role in the pathogenesis of retinal detachment, alterations of refractive components after scleral buckling procedures for retinal detachment may be an important factor for retinal redetachment. To find out the refractive change following retinal detachment surgery, we prospectively followed up the alterations of corneal curvature, and axial components (axial length, anterior chamber depth, lens thickness, and vitreous length) of 44 eyes of rhegmatogenous retinal detachment before and after operations. The procedures consisted of encircling scleral buckling (12 eyes) and segmental scleral buckling (32 eyes). All patients were followed for 6 months postoperatively. The corneal curvatures were measured with a keratometer, the axial length and axial components were measured with an A-scan ultrasonography. The methods and materials used in operation were recorded in detail to correlate with the refractive changes. The corneal curvature showed a trend to flatten early after operation (the 1st week), and gradually reversed to steepening. But, the difference was statistically significant only at the K2 (vertical meridian) in the 1st postoperative week and the K1 (horizontal meridian) in the 4th postoperative week. Lengthening of eyeballs were noted in the encircling group (12 eyes), but only the elongation in the 1st postoperative week was statistically significant. While in segmental buckling group, the axial length of the eyeballs was transiently shortened. The shortening was significant in the 2nd, 4th, and 6th week after operation. The reduction of eyeball's axial length was related to the shortening of vitreous length and shallowing of anterior chamber.(ABSTRACT TRUNCATED AT 250 WORDS)

Gluteus medius tendon tears and avulsive injuries in elderly women: imaging findings in six patients.

OBJECTIVE: The purpose of this study is to describe the imaging findings of tears and avulsive injuries of the gluteus medius tendon in elderly women and to evaluate the importance of diagnosis and the implications of treatment in the realm of lateral hip pain. CONCLUSION: Elderly women are susceptible to a spectrum of gluteal tendon abnormalities of the hip, notably tears and avulsive injuries of the gluteus medius tendon, that can be a cause of lateral hip pain and may be underdiagnosed or misdiagnosed. The MR imaging findings of this entity are instrumental in establishing the correct diagnosis in the setting of lateral hip pain and initiating appropriate treatment.

[The ocular fundus findings in dengue fever].

From September to December of 1988, 24 cases of clinical diagnosed dengue fever accompanied by visual disturbances were studied. A detailed history and a detailed ocular examination including visual acuity, slit lamp examination, fundus examination through dilated pupil and fluorescein angiography were conducted. In some cases, Amsler grid, visual field, visual evoked potential and color vision test were also evaluated. The chief complaints of these 24 patients were blurred vision, central scotoma, floaters, photophobia and halo vision. The intervals between onset of fever and awareness of blurred vision were 2 to 15 days with an average of 7.26 days. The ocular fundus changes included macular hemorrhage, retinal hemorrhage, maculopathy, Roth's spot, diffuse retinal edema, peripapillary hemorrhage vitreous cells and blurring optic disc. The fluorescein angiographic findings included poor choroidal flushing, delayed disc filling, disc extravasation, block fluorescence, capillary obliteration, non filling of macular network, capillary leakage and window defect. Seventeen cases (30 eyes) were followed-up for 2 weeks to 3 months. Visual recovery was good in most of the cases. However, 2 cases (4 eyes) showed poor visual outcome. In this series studied, the principle ocular fundus change caused by dengue fever was macular hemorrhage. This may be due to the capillary changes near the macular area. But in some of the cases, the direct viral invasion and/or indirect changes of the optic nerve, the retinal pigment epithelium or photoreceptors should be considered.

The hamatolunate facet: characterization and association with cartilage lesions--magnetic resonance arthrography and anatomic correlation in cadaveric wrists.

The objective of this study was to characterize the appearance of the hamatolunate facet using high-resolution magnetic resonance (MR) arthrography in cadavers and to correlate the presence of this anatomic variant with the presence of osteoarthritis in the wrist. High-resolution MR images of 22 cadaveric wrist specimens were obtained after tri-compartmental arthrography. Two readers in consensus analyzed the MR images and recoded the presence or absence of a hamatolunate facet. Geometric characteristics and cartilage and ligament integrity were analyzed. A third reader, who was blinded to the purpose of the study, recorded cartilage lesions of all the bones of the proximal and distal carpal rows. A hamatolunate facet was present in 11 of 22 wrists (50%). The mean coronal size of the lunate facet at the lunate (type II lunate) was 4.5 mm (range, 2-6 mm). The highest frequencies of cartilage lesions were seen in the scapho-trapezio-trapezoid joint (45.5%) and at the proximal pole of the hamate (54.4% and 40.9% for consensus reading/blinded reading, respectively). In cases with a hamatolunate facet, the frequency of cartilage lesions in the proximal pole of the hamate was 81.8% and 63.6% versus 27.3% and 18.2% without such a facet (chi-squared, P=0.01/ P=0.03). No correlation of the presence of a hamatolunate facet with interosseous ligament tears or lesions of the triangular fibrocartilage was seen. In conclusion, the hamatolunate facet is a very common anatomic variant. The presence of a hamatolunate facet is associated with cartilage damage in the proximal pole of the hamate.

Plantar calcaneal enthesophytes: new observations regarding sites of origin based on radiographic, MR imaging, anatomic, and paleopathologic analysis.

OBJECTIVE: To determine the relationship between sites of calcaneal plantar enthesophytes and surrounding fascial and soft tissue structures using routine radiography, MR imaging, and data derived from cadaveric and paleopathologic specimens. DESIGN AND PATIENTS: Two observers analyzed the MR imaging studies of 40 ankles in 38 patients (35 males, 3 females; mean age 48.3 years) with plantar calcaneal enthesophytes that were selected from all the ankle MR examinations performed during the past year. Data derived from these MR examinations were the following: the size of the enthesophyte; its location in relation to the plantar fascia (PF) and flexor muscles; and the thickness and signal of the PF. The corresponding radiographs of the ankles were evaluated at a different time by the same observers for the presence or absence of plantar enthesophytes and, when present, their measurements. A third observer reviewed all the discordant observations of MR imaging and radiographic examinations. Two observers analyzed 22 calcaneal specimens with plantar enthesophytes at an anthropology museum to determine the orientation of each plantar enthesophyte. MR imaging of a cadaveric foot with a plantar enthesophyte with subsequent sagittal sectioning was performed to provide further anatomic understanding. RESULTS: With regard to MR imaging, the mean size of the plantar enthesophytes was 4.41 mm (SD 2.4). Twenty (50%) enthesophytes were located above the PF, 16 (40%) between the fascia and abductor digiti minimi, flexor digitorum brevis and abductor hallucis muscles, and only one (3%) was located within the PF. In three (8%) cases the location was not determined. The size of enthesophytes seen with MR imaging and radiographs was highly correlated (P<0.01). The interobserver agreement for all measurements was good (Pearson >0.8, kappa >0.9). Eleven of the 22 bone specimens had plantar enthesophytes oriented in the direction of the abductor digiti minimi and 11 oriented in the direction of the flexor digitorum brevis and PF. The cadaveric sections revealed different types of enthesophytes. CONCLUSIONS: Plantar calcaneal enthesophytes arise in five different locations: at the insertion sites of abductor digiti minimi and flexor digitorum brevis muscles; between the PF and these muscles; and, less frequently, within the PF and at the insertion site of the short plantar ligament.