Hallux valgus and hallux rigidus: MRI findings

The purpose of this article is to describe the MR findings of Hallux Valgus (HV) and Hallux Rigidus (HR). Twenty-four patients (11 with HV, 4 with HR, and 9 with both HV and HR) were studied at 1.5 Tesla MRI. Two separate observers evaluated the first ray blindly for the following signs: sesamoid position, sesamoid proliferation, hypertrophy of the median eminence, presence of a lateral facet, presence of an adventitial bursa, shape of the first metatarsal head, relative length of the first metatarsal, joint space loss, osteophytes (dorsalor lateral), marrow edema, geodes, subchondral sclerosis, intra-articular ossicle, and pes planus. The most common findings observed in HV were a hypertrophic medial eminence (95%), sesamoid proliferation (90%) and adventitial bursitis (70%). The most common findings observed in HR were osteophytes (77% and 69%), geodes, and marrow edema. We conclude that traditional routine radiograph signs of HV and HR may be applied to MR images.

The septic versus nonseptic inflamed joint: MRI characteristics

OBJECTIVE

To differentiate the MR features of septic versus nonseptic inflamed joints.

DESIGN AND PATIENTS

Thirty patients were referred for MRI with inflamed joints (19 were subsequently found to be septic and 11 nonseptic). At 1.5 T enhanced MRI five groups of signs related to joint space, synovium, cartilage, bone and peri-articular soft tissue respectively were assessed and compared between the septic and nonseptic groups.

RESULTS

The prevalence of MRI findings in septic versus nonseptic joints (respectively) was as follows: effusion (79% vs 82%), fluid outpouching (79% vs 73%), fluid heterogeneity (21% vs 27%), synovial thickening (68% vs 55%), synovial periedema (63% vs 55%), synovial enhancement (94% vs 88%), cartilage loss (53% vs 30%), bone erosions (79% vs 38%), bone erosions enhancement (77% vs 43%), bone marrow edema (74% vs 38%), bone marrow enhancement (67% vs 50%), soft tissue edema (63% vs 78%), soft tissue enhancement (67% vs 71%), periosteal edema (11% vs. 10%). The presence of bone erosions appeared to be an indicator for an infected joint (P=0.072); coexistence of bone marrow edema slightly improves the significance (0.068). A similar trend was obtained when combining bone erosions with either synovial thickening, synovial periedema, bone marrow enhancement or soft tissue edema (P=0.075).

CONCLUSIONS

The combination of bone erosions with marrow edema is highly suggestive for a septic articulation; the additional coexistence of synovial thickening, synovial edema, soft tissue edema or bone marrow enhancement increases the above level of confidence. Similar to conventional radiography, the single sign that appeared to show a significant trend was the presence of bone erosions. However, no single sign or combination could either be considered pathognomonic or exclude the presence of a joint infection.

MR imaging of plantar fasciitis: edema, tears, and occult marrow abnormalities correlated with outcome

OBJECTIVE

We sought to evaluate various MR imaging signs of plantar fasciitis and to determine if a difference in these findings exists between clinically typical and atypical patients with chronic symptoms resistant to conservative treatment.

CONCLUSION

We found signs on MR imaging that, to our knowledge, have not been described in the scientific literature for patients with plantar fasciitis. These signs included occult marrow edema and fascial tears. Patients with these manifestations seemed to respond to treatment in a manner similar to that of patients in whom MR imaging revealed more benign findings.

The Influence of Physical Attractiveness and Gender on Ultimatum Game Decisions

Physical appearance influences behavior in a number of environments, yet surprisingly little is known about the influence of physical attractiveness on the bargaining process. We conducted an ultimatum game experiment to investigate the influence of physical attractiveness and gender on ultimatum game decisions. Results from this study revealed no significant differences in the offers or demands attractive and unattractive people made. However, attractive people and men were treated differently by others. Consistent with the notion of a "beauty premium," attractive people were offered more, but more was demanded of them. Men were also offered more, and less was demanded of them. We discuss implications of these results with respect to bargaining and the labor market. Copyright 1999 Academic Press.

MR evaluation of subscapularis tears

PURPOSE

The purpose of this work was to describe the MR appearance of tears of the subscapularis tendon and compare the usefulness of different imaging planes as well as note the association of subscapularis tears with other rotator cuff tears and biceps tendon dislocations.

METHOD

MR studies at 1.5 T over an 8 year interval were retrospectively assessed for the presence of a rotator cuff tear and/or tear of the subscapularis tendon. Images that showed a subscapularis tear were reviewed for the presence of a visible tear separately on the axial, coronal, and sagittal images. The MR studies were also evaluated for associated tears of the supraspinatus, infraspinatus, and teres minor muscles as well as biceps tendon dislocation and the "naked humerus sign" on coronal images. Last, clinical records and surgical reports were reviewed.

RESULTS

Forty-five (2%) of 2,167 rotator cuff tears involved the subscapularis; 27% were partial and 73% were complete tears. Tears were best seen in the sagittal oblique plane. Almost all subscapularis tears were an extension of typical rotator cuff tears: supraspinatus in 35 patients (79%), extending into infraspinatus tears in 25 (56%) and into teres minor tears in 2 patients (4%). Bicipital dislocations were seen in 22 patients (49%), and three complete tears of the biceps (7%) were noted as well. The naked humerus sign was demonstrated in 31 patients (69%). Surgical reports that confirmed the MR findings were available for 15 patients.

CONCLUSION

About 2% of rotator cuff tears involve the subscapularis tendon. Most subscapularis tears are extensions of supraspinatus tears and frequently involve the biceps tendon.

MR imaging of the type II lunate bone: frequency, extent, and associated findings

OBJECTIVE

Type II lunate bones have an "extra" facet that articulates with the hamate bone, which frequently leads to arthritis. Because the only prior studies, to our knowledge, on this common and clinically significant variant involved dissection of cadavers, we performed an MR imaging study of the type II lunate.

MATERIALS AND METHODS

We retrospectively reviewed MR images obtained at 1.5 T of 186 wrists for frequency of type II lunates, size of the extra facet, amount of hamatolunate apposition, and presence of hamate subchondral edema. Of the 186 wrists, 28 also had correlation with findings on wrist arthroscopy.

RESULTS

One hundred seven wrists (57.5%) had type II lunates with an average extra facet size of 4.6 mm (range, 1.2-12.0 mm). Apposition (articulation) of the extra lunate facet with the hamate averaged 77.4% (range, 0-100%). Hamate edema was seen in only nine wrists (4.8%), all of which had type II lunates. Arthroscopic evidence of focal hamate chondromalacia and MR imaging evidence of marrow edema were seen in six of these nine wrists; marrow edema was seen only in wrists with frank cartilage changes on arthroscopy.

CONCLUSION

An extra facet (type II lunate) was seen in approximately half of 186 wrists. On MR imaging, type II lunates usually have an innocuous appearance. A large percentage of patients with type II lunates also have chondromalacia, which often is occult on MR imaging. When visible, such chondromalacia is the cause of marrow edema similar to that seen in patients with carpal fractures.

Is a subset of wrist ganglia the sequela of internal derangements of the wrist joint? MR imaging findings

PURPOSE

To determine if there is an association between wrist ganglia and internal derangements of the wrist joint by reviewing magnetic resonance (MR) images.

MATERIALS AND METHODS

Two observers retrospectively reviewed MR images of the wrist obtained in 625 patients at 1.5 T for the presence of ganglia and associated triangular fibrocartilage complex, scapholunate ligamentous, or lunotriquetral ligamentous tears that were within 3 mm of the ganglion. When available, surgery and/or pathology records were reviewed.

RESULTS

There were 122 ganglia and 37 internal derangements. Of the 22 ulnar-sided ganglia, 10 (45%) demonstrated associated triangular fibrocartilage complex tears. Of the 97 radial-sided ganglia, 27 (28%) demonstrated ligamentous tears related to the site of the ganglion. The radial-sided tears involved the radial aspect of the triangular fibrocartilage complex in 12 ganglia; the scapholunate ligament, in isolation, in eight ganglia; and both the triangular fibrocartilage complex and the scapholunate ligament in six ganglia. Only one of the ganglia demonstrated an associated lunotriquetral ligamentous tear. Surgical findings confirmed the ligamentous tears in 25 patients.

CONCLUSION

Wrist ganglia are associated, not infrequently, with internal derangements of the wrist.

The construction of mental accounts in benefits decision making

Mental accounting describes the psychological creation of separate accounts or budgets for categories of decisions. This process simplifies complex budget decisions in ways that significantly affect consumer behavior (Kahneman and Tversky 1981, 1984) and has been incorporated into economic theory (Shefrin and Thaler 1988). The impact of mental accounts on benefits decisions is likely to be significant. The creation of these accounts is context dependent, and prior work has demonstrated that the source and timing of payments affects the allocation of resources into mental accounts. Results from this work demonstrate that other normatively unimportant factors of the choice such as presentation order impact the construction of mental accounts. These results describe mental accounting biases within the context of health care benefits and demonstrate that the construction of mental accounts is highly unstable and easily manipulated within this domain.

Frequency and spectrum of abnormalities in the bone marrow of the wrist: MR imaging findings

OBJECTIVE

To describe the frequency of marrow abnormalities on wrist MR imaging and the MR findings of these various abnormalities.

DESIGN AND PATIENTS

Five hundred and nineteen patients were studied at 1.5 T. Two observers recorded the presence and location of avascular necrosis, occult fractures and arthritic edema [focal osteoarthritis, ulnolunate abutment, rheumatoid arthritis, septic arthritis, gouty arthritis and scapholunate advanced collapse (SLAC)].

RESULTS AND CONCLUSION

One hundred and eighty-seven (36%) patients demonstrated marrow abnormalities in the wrist, of which 101 were diagnosed as arthritis [64 (34%) as focal osteoarthritis, 17 (9%) as ulnolunate abutment, 15 (8%) as rheumatoid arthritis, 2 as septic arthritis, 2 as SLAC, and 1 as gouty arthritis]. Seventy-two patients had occult fractures and in 27 patients avascular necrosis was seen. MR imaging can reveal various abnormalities in bone marrow of the wrist when findings on radiography are normal or equivocal.

The cost-effectiveness of routine pelvic radiography in the evaluation of blunt trauma patients

OBJECTIVE

. To determine the cost-effectiveness of routine protocol-driven pelvic radiography in the evaluation of blunt trauma patients.

DESIGN AND PATIENTS

A retrospective review was performed on 319 blunt trauma patients who underwent protocol-driven pelvic radiography to record the frequency of pelvic fracture. Medical records of the patients in whom fractures were identified radiographically were then examined to determine the clinical suspicion of injury prior to radiography. Using Medicare reimbursement data, the cost-effectiveness of routine pelvic radiography was calculated in terms cost per pelvic radiograph with evidence of fracture. These values were then compared with literature values of other screening studies, namely mammography and colonoscopy.

RESULTS

Thirty-eight of 319 patients (11.9%) were found to have fractures identified on routine pelvic radiography. Using the 1997 Medicare reimbursement charge of $27.79 for a single anteroposterior radiograph of the pelvis, the total cost of performing these 319 trauma protocol-driven studies was calculated as $8865.01. The cost per protocol-driven pelvic radiograph with evidence of pelvic fracture was subsequently determined to be $233.29. Only 18 (47.4%) of these 38 patients were suspected to have pelvic fracture on the basis of the clinical findings alone.

CONCLUSIONS

Trauma protocol-driven pelvic radiography is a necessary and cost-effective means of identifying acute pelvic injury in all trauma patients regardless of clinical presentation.

Economic evaluation of breast cancer screening: A review

PURPOSE

The authors provide a review of the economic evaluation literature of breast cancer screening and identify important trends and gaps in the literature.

OVERVIEW

Healthcare resources are limited and economic evaluation plays a critical role in resource allocation, healthcare policy, and clinical decisions. Many economic evaluations of medical practice, however, are unreliable and do not use appropriate analytic techniques. Three important trends were observed. First, two economic evaluation methods are dominant. Second, a wide range of cost estimates exists across studies. Third, a lack of standardization exists across studies with regard to basic economic evaluation principles. These findings should be considered when conducting future research, analyzing economic evaluations of breast cancer screening, and developing clinical guidelines.

CLINICAL IMPLICATIONS

Concerns about cost containment in healthcare make it necessary for physicians and clinical administrators to take an active role in resource allocation decisions at the clinical level. For instance, the recent debate on the proper age to begin annual mammography screening involves both resource allocation and clinical issues. Thus, it is important for physicians and clinical administrators to be familiar with the economic evaluation literature of breast cancer screening, economic evaluation methodology, and the associated shortcomings of published estimates.

Repeat tear of postoperative meniscus: potential MR imaging signs

PURPOSE

To determine the usefulness of five magnetic resonance (MR) signs of repeat tears of the postoperative meniscus.

MATERIALS AND METHODS

Fat-saturated proton-density-weighted and T2-weighted MR images in 20 patients who had undergone at least two knee surgeries were reviewed. Second-look arthroscopic confirmation of meniscal status was available in all patients. MR images of 39 menisci (10 repeat tears, 11 postoperative menisci without repeat tears, three tears in previously normal menisci, and 15 normal menisci) were evaluated for (a) a linear area of abnormal signal intensity extending to an articular surface on intermediate-weighted images, (b) abnormal meniscal morphology, (c) likelihood of a typical postoperative appearance, (d) fluid extending into the linear area on T2-weighted images, and (e) cartilage defects. Two radiologists rated their confidence on a five-point scale for the presence of these signs and were compared for level of agreement.

RESULTS

The intraclass correlation coefficient (range, 0.75-0.91) indicated a high level of agreement. Areas under the receiver operating characteristic curves were large (range, 0.70-0.87) for all five signs, with a line (grade 3 signal intensity) and fluid within a line having the highest areas. These two signs also had the highest statistical scores (chi 2 = 14.12 and 13.30; P < .002; odds ratio, 1.588 and 1.599 for the line and the fluid within the line, respectively).

CONCLUSION

The two best MR signs of repeat tear of the postoperative meniscus were the presence of a line and fluid within the line extending to an articular surface.

MRI in patients with intraspinal bullets

The purpose of this study was to determine whether neurologic sequelae occur in patients with intraspinal bullets or bullet fragments who undergo magnetic resonance imaging (MRI). Nineteen patients with bullets or bullet fragments adjacent to the cord or nerve roots underwent clinical MRI studies at 1.5 T. Sequences included conventional spin echo, fast spin echo, gradient-recalled echo, and inversion recovery. Patients were queried during scanning for symptoms of discomfort, pain, or change in neurologic status. Detailed neurologic examinations were performed prior to MRI (baseline), post MRI, and at the patients' discharge. Sixteen patients were completely paralyzed (ASIA-A), and three were not paralyzed. The length of time from injury was 2-24 months. No patients experienced pain or discomfort during the procedure. No change in neurologic status occurred. Follow-up radiographic studies showed no bullet movement following the scanning. We conclude that in patients with complete spinal cord injury, MRI in patients with intraspinal bullets may be performed.

Increased soft-tissue blood flow in patients with reflex sympathetic dystrophy of the lower extremity revealed by power Doppler sonography

OBJECTIVE

We evaluated the ability of power Doppler sonography to show increased soft-tissue blood flow in patients with reflex sympathetic dystrophy of the lower extremity.

SUBJECTS AND METHODS

Power Doppler sonography was performed in 30 patients with reflex sympathetic dystrophy of the lower extremity and in 26 asymptomatic control subjects. The bilateral power Doppler sonograms that were obtained of the soft tissues of the dorsum of the foot of each subject were grouped in pairs, and three sonologists who were unaware of clinical information independently reviewed the images. Images were evaluated for the amount of power Doppler signal shown on the following scale: 1 = no flow or minimal flow; 2 = mild flow; 3 = moderate flow; and 4 = marked flow.

RESULTS

More power Doppler flow was seen in the patients with reflex sympathetic dystrophy than in the control subjects (p < .005). In addition, side-to-side asymmetry of flow was seen in patients, but this trend was not statistically significant (p < .20). Receiver operating characteristic (ROC) analysis showed that combined flow and asymmetry were more related to reflex sympathetic dystrophy than either parameter alone (area under the ROC curve: for flow, 0.748; for asymmetry, 0.566; for both, 0.799). We found that when the sum of power Doppler flow in both feet was greater than or equal to five, and asymmetry of flow was greater than or equal to one, the sensitivity of power Doppler sonography for reflex sympathetic dystrophy was 73% and the specificity was 92%.

CONCLUSION

Patients with reflex sympathetic dystrophy of the lower extremity have increased power Doppler flow compared with asymptomatic control subjects. Patients may also exhibit more side-to-side asymmetry of flow than control subjects.

The cost-effectiveness of oblique radiography in the exclusion of C7-T1 injury in trauma patients

OBJECTIVE

The purpose of our study was to compare the cost-effectiveness of bilateral oblique radiography with that of CT for excluding C7-T1 injury in trauma patients.

MATERIALS AND METHODS

Using a historical cohort model, we retrospectively studied two distinct groups of trauma patients. In the first group, which included 196 patients, CT was performed to show C7-T1 anatomy when this region was not adequately revealed on initial three-view cervical spine radiography. In the second group, which included 129 patients, routine three-view radiography was complemented by bilateral oblique views. If these five views failed to adequately reveal C7-T1 anatomy, CT was then performed to show the cervicothoracic junction. Using Medicare reimbursement data, we then compared the cost-effectiveness of CT with that of oblique radiography in terms of cost per cervical spine imaged completely to the level of C7-T1.

RESULTS

In the first group, 50 (26%) of 196 patients underwent CT when C7-T1 anatomy was not adequately revealed on routine three-view cervical spine radiography. In the second group, only 17 (13%) of the 129 patients required CT when five-view radiography failed to adequately reveal C7-T1 anatomy. This difference was statistically significant (p < .01). The cost per completely imaged cervical spine was $92.00 when bilateral oblique radiographs were routinely obtained, compared with $116.28 per completely imaged cervical spine when these views were not obtained.

CONCLUSION

Because bilateral oblique radiography appears to be cost-effective for the exclusion of cervical spine injuries, we suggest that it be performed routinely.

Occult osseous injuries after ankle sprains: incidence, location, pattern, and age

We retrospectively evaluated 109 magnetic resonance studies in patients with prior ankle sprains to investigate the frequency and pattern of bone bruises. Patterns of bone bruises were then correlated with the ligaments injured. In addition, the age of the injury was determined from medical records to correlate the presence of bone bruises with the temporal period from injury. Bone bruises occurred in 39% of ankle sprains. Multiple bone bruises were seen in 40% of those with bone bruises; they occurred more frequently in patients with multiple ligaments injured. The marrow changes may be secondary to impaction, rotary instability of the ankle, and microavulsion vectors. Bone bruise-like lesions were seen at an average of 8.4 weeks in age but were seen more than a year after the injury. We conclude that bone bruises frequently occur in patients with ankle sprains, and the marrow changes may be caused by one of the three proposed mechanisms.

Usefulness of MRI in isolated upper cervical spine fractures in adults

A prospective analysis of patients admitted with isolated upper cervical spine fractures and who had magnetic resonance (MR) imaging performed within 48 h of the inciting traumatic event was completed to determine the clinical usefulness and cost effectiveness of routine MR screening. In patients with an identified neurologic deficit, MR findings changed the treatment of 25% (one of four) of the patients, whereas MR findings did not change the treatment of any patient identified without a neurologic deficit. We recommend that in adult patients with an isolated upper cervical spine fracture, MR should not be routinely ordered in patients without a neurologic deficit. This advanced imaging modality is not a useful or cost-effective screening device for patients presenting with a fracture of the upper cervical spine without neurologic deficit.

Disorders of the hallux sesamoid complex: MR features

Numerous painful conditions can affect the first metatarsophalangeal-sesamoid joint complex. Symptoms can be of sudden or insidious onset, and be of acute or chronic duration. Although conventional radiography is recognized as the initial diagnostic procedure for these symptoms, there is often a need to proceed to MR imaging. MR imaging is sensitive and can be utilized in the investigation of the hallux sesamoid complex to differentiate soft tissue from osseous pathology. Synovitis, tendonitis, and bursitis can be distinguished from bony abnormalities such as sesamoid fracture, avascular necrosis, and osteomyelitis. An understanding of MR imaging features and techniques will result in the highest diagnostic yield. Early and accurate diagnosis of sesamoid complex disorders can guide the physician to the appropriate clinical management and prevent potentially harmful longstanding joint dysfunction.

Magnetic resonance imaging of ankle ligament injuries correlated with time

Ankle sprain is one of the most commonly treated injuries of the lower extremity. The treatment depends on the severity of the injury and the time at which it occurred. The physician must rely on the history as related by the patient to determine the age of the injury. Magnetic resonance imaging has been proven to help determine the severity of the injury but has not been used to determine the age of the injury. The present study was conducted to identify the typical findings of acute and chronic ankle sprains as a means of dating an ankle sprain based on its appearance on magnetic resonance imaging.

Hip joint fluid: detection and distribution at MR imaging and US with cadaveric correlation

PURPOSE

To define the magnetic resonance (MR) imaging appearance of a hip effusion.

MATERIALS AND METHODS

Fifty-two asymptomatic hips in 26 volunteers aged 20-37 years and five fractured hips were imaged at 1.5 T with T2-weighting in three planes. Images were computer digitized and analyzed for hip fluid volume and visually assessed for the presence and width of fluid pockets (in millimeters) seen in the acetabular notch; recesses anterior, posterior, and lateral to the femoral head; and recesses anterior, posterior, and medial to the femoral neck. Cadaveric hips were also injected with graduated amounts of saline (1-20 mL), and sequential MR and ultrasound images were obtained.

RESULTS

Computer analysis yielded an average fluid volume of 2.7 mL (range, 0.7-5.6 mL) in asymptomatic and 6.1 mL (range, 1.7-11.6 mL) in symptomatic hips. The mean difference between the right and left hips was 0.8 mL (range, 0.0-2.9 mL). Discrete fluid pockets, sometimes measuring greater than 5 mm in width, were commonly seen in asymptomatic hips. Distention of the capsule by at least 5 mm along the length of the femoral neck was almost always seen after injection of 5 mL of saline and was consistently seen after injection of 10 mL of saline into cadaveric hips.

CONCLUSION

Fluid adjacent to the entire length of the femoral neck, measuring at least 5 mm in width, is compatible with a joint effusion.

Osteomyelitis of the foot: relative importance of primary and secondary MR imaging signs

PURPOSE

To determine the usefulness of primary and secondary magnetic resonance (MR) imaging signs of osteomyelitis.

MATERIALS AND METHODS

MR imaging at 1.5 T was performed in 73 feet (62 patients) with clinical concern for osteomyelitis. Images were reviewed retrospectively and separately by two reviewers in a blinded fashion for primary (abnormal marrow signal intensity) and secondary (ulcer, cellulitis, soft-tissue mass, abscess, sinus tract, cortical interruption) signs associated with osteomyelitis.

RESULTS

Of the 73 feet, 43 had osteomyelitis. Discordant marrow signal intensity between individual MR sequences was observed by reader 1 in six (8%) feet and by reader 2 in 15 (21%) feet. For primary signs, fast spin-echo short inversion time inversion-recovery and gadolinium-enhanced fat-suppressed T1-weighted images had the highest sensitivity, and T1-weighted and gadolinium-enhanced fat-suppressed T1-weighted images had the highest specificity and least interobserver variability. Signs of cutaneous ulcer, sinus tract, and cortical interruption had the highest positive predictive value for osteomyelitis; signs of soft-tissue mass and cortical interruption had the highest negative predictive value. All had good interobserver agreement except cellulitis.

CONCLUSION

When osteomyelitis of the foot is suspected, marrow signal intensity can differ on different types of MR images. Identification of secondary signs may augment diagnostic confidence when abnormal marrow signal intensity is seen.

Color Doppler hemodynamic evaluation of flow to normal hip

This study was aimed to quantitate hemodynamic flow to the normal proximal femur and to evaluate the effect of internal rotation on blood flow measurements in the hip to assess the capability of Doppler ultrasonography to detect a simulated ischemic situation. Forty hips in 20 adult healthy volunteers age 22 to 62 years (mean age, 39.5 years) were examined in the supine position in neutral position and during internal rotation (simulated ischemia). Medial and lateral circumflex arteries and veins were examined using standard ultrasound equipment with color and power Doppler capabilities. Arterial pulsatility index and maximal arterial and venous velocities were determined. Pulsatility index values in the medial circumflex artery were significantly (P < 0.05) changed during internal rotation of the leg. A drop in pulsatility index of more than 1.4 on the right and 2.2 on the left hip with respect to the normal neutral position was considered abnormal. The peak systolic velocity did not change significantly. The venous return showed a consistent increase in flow velocity during internal rotation, but this was borderline in terms of significance. Participants older than 40 years showed more prominent changes in pulsatility index during internal rotation. Repeat measurements performed in 10 hips showed only a 5% mean change in the pulsatility index values from the previous series of measurements. Changes in pulsatility index values occurred when flow in the proximal femur was compromised (internal rotation). These changes were particularly significant in the medial circumflex artery, which is the primary vascular supply of the femoral head and neck. Changes also were observed in the circumflex veins (velocity increased) on internal rotation; however, they were not statistically significant. Doppler ultrasonography of the medial circumflex artery is a potential tool for the assessment and follow-up of hip vascularity.

Osteomyelitis of the pelvis/hips in paralyzed patients: accuracy and clinical utility of MRI

PURPOSE

The goal of our study was to determine the accuracy and clinical utility of MRI in the diagnosis of osteomyelitis of the pelvis/hips in paralyzed patients.

METHOD

In 44 paralyzed patients, 59 consecutive MR examinations of the pelvis/hips were evaluated prospectively. Criteria for diagnosis of osteomyelitis were based on those established in previous studies of complex, nonhematogenous osteomyelitis (diabetic foot). Average follow-up was 3 years. The standard of reference for the diagnosis of osteomyelitis was histologic/microbiologic results of surgical biopsy specimens or clinical follow-up. Note was made if decubitus ulcers, sinus tract, fistula, fluid collection, abscess, septic arthritis, joint effusion, bursitis, or heterotopic ossification was present on MRI. Comparison of the extent of infection by MRI and surgical margins was performed. Effect on surgical treatment was defined by absence of recurrent infection at the surgical site within 6 weeks of limited resection.

RESULTS

The criteria for diagnosis of osteomyelitis were fulfilled in 49 of 57 MR studies for an overall accuracy of 97%. There was one false-negative MR study. MRI for the diagnosis of osteomyelitis yielded a sensitivity of 98% and a specificity of 89%. There were 41 decubitus ulcers, 28 sinus tracts, 2 fistulae, 14 fluid collections, 15 abscesses, 9 hips with septic arthritis, 10 "bland" hip effusions, 5 cases of trochanteric bursitis, and 30 patients with heterotopic ossification. Twenty-one patients underwent limited surgical resection guided by MR findings in which only the enhancing area was resected. There was only one recurrence of osteomyelitis at the surgical margins.

CONCLUSION

MRI is accurate in the diagnosis of osteomyelitis and associated soft tissue abnormalities in spinal cord-injured patients. MRI can delineate the extent of infection in guiding limited surgical resection and preserving viable tissue.