Post-transplant lymphoproliferative disorder presenting with multifocal aggressive osseous lesions.

Post-transplantation lymphoproliferative disorder (PTLD) encompasses a broad category of lymphoid and plasmacytic proliferations that occur following solid organ and/or allogeneic stem cell transplantation. PTLD manifests in the setting of chronic immunosuppression and is thought to be associated with the Epstein Barr Virus, although Epstein Barr Virus infection or reactivation is not required for the process to occur. Pathologic correlation is necessary for diagnosis with B-cell lymphocytes the most commonly isolated cellular etiology. There is a broad range of clinical and imaging presentations of PTLD with intestinal and nodal involvement being the most common. Imaging plays an integral part in the diagnosis and management of PTLD, as it is utilized in the initial diagnosis and staging, guiding biopsy of lesions, and gauging treatment response. Presenting symptoms of PTLD are often vague and nonspecific and depend on the organ systems affected. Musculoskeletal involvement is especially rare, with only a few cases described in the literature. We present a case with multifocal osseous manifestations of PTLD occurring years after a renal living donor transplant.

3D Morphometric Analysis of Normal Sacroiliac Joints: A New Classification of Surface Shape Variation and the Potential Implications in Pain Syndromes.

BACKGROUND: Normal sacroiliac (SI) joints vary widely in shape, and it is unclear whether SI joint morphology plays a role in the development of pain. To answer this question, we used 3D-CT surface rendering to image healthy study participants and used the resulting images to develop a classification system for SI joint morphology. In a case-control study comparing health research participants to patients with SI pain, we assessed whether the classification of SI joint morphology was associated with pain. OBJECTIVES: We aimed to define normal variation in area and shape of the synovialized SI joint. We also aimed to determine interactions between joint area and shape and SI pain in men and women. STUDY DESIGN: A retrospective cohort study. SETTING: University hospital tertiary care center. METHODS: We conducted a retrospective case-control study. We acquired 3D-CT surface rendered images of the SI joint in 223 normal controls and 34 patients with SI pain syndrome. We measured the sacral and iliac surface areas and performed morphologic 3D assessment of both articular surfaces. We classified SI joints into 3 types based on morphology (types one, 2, and 3). We used descriptive statistics to provide a reference standard for normal SI joints. We used multivariate models to assess whether articular surface area differed between study participants with and without SI pain. We also assessed the association between morphology type and the presence of pain. RESULTS: Sacral and iliac surface areas differ by participant gender. Sacral and iliac surface area was associated with SI joint pain in both men (P = 0.0007) and in women (P = 0.02). In women (P = 0.04), but not in men (P = 0.11), joint shape was associated with pain. LIMITATIONS: A retrospective study may create potential for misclassification bias if SI joint symptoms/histories were present but not well-documented in the electronic medical record. A lack of clinical standardization in the pre-procedural assessment of SI joint pain via provocative maneuvers (FABER, etc.) is also a limitation. CONCLUSIONS: Our study provides insight into the association between shape and joint surface area and SI joint pain. Further, prospective studies will allow us to determine the role of joint shape and surface area in the patho-etiology of SI joint pain, and thus provide information for patients and physicians about prevention or treatment. KEY WORDS: Sacroiliac joint, spine pain, 3D reformation, SI joint area, SI joint shape, SI joint pain syndrome.

Lateral acetabular labral length is inversely related to acetabular coverage as measured by lateral center edge angle of Wiberg.

Patients with developmental dysplasia of the hip often have compensatory labral hypertrophy, which presumably lends stability to an unstable joint. Conversely, patients with acetabular overcoverage may have small or ossified labra. The purpose of this study is to explore the interaction of labral length with the degree of acetabular hip coverage. A retrospective cohort of patients with hip pain presenting to a hip preservation center, who had undergone hip magnetic resonance imaging and AP pelvis radiographs were studied. General linear multivariate models were used to assess the association between three measures of labral length (lateral, anterior and anterior inferior locations along the acetabular rim) and the X-ray derived lateral center edge angle (LCEA) of Wiberg. Of the three acetabular labral locations measured, only the lateral labrum was associated with LCEA Wiberg (P = 0.0008). Lateral labral length increases as LCEA of Wiberg decreases. The anterior and anterior inferior labral locations did not show a predictable increase in labral length as LCEA Wiberg decreased.

Validation of neck axis distance as a radiographic measure for acetabular anteversion.

Excessive acetabular anteversion is an important treatment consideration in hip preservation surgery. There is currently no reliable quantitative method for determining acetabular anteversion utilizing radiographs alone. The three main purposes of this study were to: (i) define and validate the neck axis distance (NAD) as a new visual and reproducible semi-quantitative radiographic parameter used to measure acetabular anteversion; (ii) determine the degree of correlation between NAD and computed tomography (CT)-measured acetabular anteversion; (iii) establish a sensitive and specific threshold value for NAD to identify excessive acetabular anteversion. This retrospective cohort study included all patients presenting to a single institution over a 14-month period who had undergone a dedicated musculoskeletal CT pelvis along with a standardized anteroposterior (AP) pelvis radiograph. Trained observers measured the NAD on the AP pelvis radiograph and equatorial acetabular anteversion on CT for all hips. Mixed model analysis was used to find prediction equations, and ROC analysis was used to evaluate the diagnostic accuracy of NAD. NAD is a valid semi-quantitative predictor of acetabular anteversion and strongly correlates with CT-measured equatorial acetabular anteversion (P < 0.0001). A NAD measurement of greater than 14 mm predicts excessive acetabular anteversion with 76% sensitivity and 78% specificity. NAD is an accurate radiographic predictor of acetabular anteversion, which may be readily used as an effective screening tool during the evaluation of patients with hip pain.

Lateral Acetabular Coverage Predicts the Size of the Hip Labrum.

BACKGROUND: Bony morphological abnormalities of the hip joint are often accompanied by adaptive soft tissue changes. These adaptive changes, if better understood and characterized, may serve to inform clinical decision making. PURPOSE: To investigate the correlation between the size of the hip labrum and lateral acetabular coverage in patients at our hip preservation clinic. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A cohort of 236 patients seen at a dedicated hip preservation service between June 2013 and June 2015 were retrospectively analyzed. Patients were grouped according to the degree of acetabular coverage, as measured by the lateral center-edge angle (LCEA): normal acetabular coverage (25°-39.9°), acetabular overcoverage (≥40°), borderline dysplasia (20°-24.9°), and frank dysplasia (<20°). Preoperative magnetic resonance imaging was utilized to measure the length of the labrum at 3 locations: laterally, anteriorly, and anteroinferiorly. RESULTS: Frankly dysplastic and borderline dysplastic hips exhibited larger values of labral length at all locations when compared with hips with normal acetabular coverage (P < .001) or acetabular overcoverage (P < .001). Interestingly, mean labral length values in frank dysplasia were statistically similar to corresponding measurements in borderline dysplasia. In hips with frank dysplasia, borderline dysplasia, or normal acetabular coverage, labral length was consistently greatest at the lateral labrum and correspondingly lowest at the anteroinferior labrum (P < .001). In hips with acetabular overcoverage, labral length did not vary significantly between the lateral, anterior, and anteroinferior locations. Multivariate analyses confirmed LCEA to be the strongest predictor of labral length, irrespective of measurement location. CONCLUSION: Patients with borderline dysplasia and frank dysplasia exhibited increased values of labral length in the weightbearing zone, potentially indicating a compensatory reaction to the lack of bony coverage. Labral length may serve as an instability marker and inform clinical decision making for patients with borderline dysplasia.

Effect of the Location of Endplate Cement Extravasation on Adjacent Level Fracture in Osteoporotic Patients Undergoing Vertebroplasty and Kyphoplasty.

BACKGROUND: The most widely researched risk/complication following vertebroplasty (VP) or kyphoplasty (KP) is that of adjacent level fracture (ALF). Current literature results regarding the effect of intradiscal extravasation of cement on the risk of ALF is conflicting with about half of the studies concluding there is no added risk with endplate extravasation and half of the studies reporting opposite conclusions. OBJECTIVE: The purpose of the study is to further stratify the data to determine whether specifically the location and extent of endplate cement extravasation more strongly affect ALF risk in osteoporotic patients following either VP or balloon KP. STUDY DESIGN: Retrospective cohort study. SETTING: University teaching hospital. METHODS: One hundred and fifty-six cemented levels in 80 patients, treated at a single center between 2008 and 2012 were reviewed. Age, gender, T-score, body mass index, and osteoporosis type (primary or secondary) were recorded. An ALF was defined as a fracture: 1) in a non-cemented vertebra; 2) adjacent to a cemented level; and 3) not due to trauma or malignancy. Location of the cement extravasation (anterior, middle, or posterior third of the vertebral body) and extravasation extent (percentage of the intervertebral disc height occupied by the bolus) were measured. A logistic modeling strategy permitted examining the association between the location and extent of extravasation and the odds of ALF. RESULTS: ALF occurred in 14 of the 52 patients (27%) and 20 of the 98 levels (20.4%) remaining after exclusions. Odds of ALF were 5.9 times higher (95% CI: 1.6 to 21.2, P = 0.008) with extravasation when compared to no leakage. Odds of ALF in a given patient were 22.6 times higher (95% CI: 3.0 to 170.9, P = 0.003) with anterior extravasation when compared to no leakage. Leakage in the middle or posterior thirds and extent of extravasation were not associated with ALF. LIMITATIONS: Limitations of the study include the retrospective study design and small sample size as well as the retrospective implementation of follow-up criteria posing risk of selection bias. CONCLUSIONS: Cement endplate extravasation isolated to the anterior third of the vertebral body is associated with is significantly higher odds of ALF after VP or KP in patients with osteoporosis.

Validation of a new radiographic measurement of acetabular version: the transverse axis distance (TAD).

OBJECTIVES: This study has three aims: (1) validate a new radiographic measure of acetabular version, the transverse axis distance (TAD) by showing equivalent TAD accuracy in predicting CT equatorial acetabular version when compared to a previously validated, but more cumbersome, radiographic measure, the p/a ratio; (2) establish predictive equations of CT acetabular version from TAD; (3) calculate a sensitive and specific cut point for predicting excessive CT acetabular anteversion using TAD. MATERIALS AND METHODS: A 14-month retrospective review was performed of patients who had undergone a dedicated MSK CT pelvis study and who also had a technically adequate AP pelvis radiograph. Two trained observers measured the radiographic p/a ratio, TAD, and CT acetabular equatorial version for 110 hips on a PACS workstation. Mixed model analysis was used to find prediction equations, and ROC analysis was used to evaluate the diagnostic accuracy of p/a ratio and TAD. RESULTS: CT equatorial acetabular version can accurately be predicted from either p/a ratio (p < 0.001) or TAD (p < 0.001). The diagnostic accuracies of p/a ratio and TAD are comparable (p =0.46). Patients whose TAD is higher than 17 mm may have excessive acetabular anteversion. For that cutpoint, the sensitivity of TAD is 0.73, with specificity of 0.82. CONCLUSION: TAD is an accurate radiographic predictor of CT acetabular anteversion and provides an easy-to-use and intuitive point-of-care assessment of acetabular version in patients with hip pain.

Measurement of lateral acetabular coverage: a comparison between CT and plain radiography.

UNLABELLED: We prospectively evaluated the degree of absolute agreement between measurements of lateral center-edge angle (LCEA) on plain radiography (XR) and computed tomography (CT) in a consecutive cohort of 205 patients (410 hips) undergoing hip arthroscopy. Preoperative measurements of the LCEA were performed bilaterally utilizing standardized anteroposterior radiographs and coronal reformatted CT scans. Demographic variables including age, gender, height, weight, BMI and clinical diagnosis were recorded for all patients. Overall, measured values of the LCEA were 2.1° larger on CT compared with XR (32.9° versus 30.8°, P < 0.001). Subgroup analysis revealed the highest mean difference in hips with acetabular dysplasia and concomitant cam-type femoroacetabular impingement (FAI) [mean difference (CT-XR) 5.5°, 95% confidence interval (CI) 3.7°-7.3°, P = 0.011], followed by hips with isolated acetabular dysplasia (mean difference [CT-XR] 4.9°, 95% CI 2.7°-7.0°, P < 0.001). In contrast, 119 (29.0%) of the hips demonstrated larger measurements of the LCEA on 25 XR relative to CT. Of these hips, 20 (16.8%) had pincer-FAI and 25 had cam-FAI (21.0%), representing a significantly higher proportion compared with all other clinical subgroups (P = 0.045 and 0.036, respectively). Our study demonstrates measured values of the LCEA are consistently inflated on CT relative to XR for a wide variety of hip pathologies, highlighting the need for standardization and validation of CT-based measurements to improve the quality of clinical decision making. LEVEL OF EVIDENCE: Diagnostic Level II.

Normal anatomy and imaging of the hip: emphasis on impingement assessment.

A comprehensive knowledge of normal hip anatomy and imaging techniques is essential in the evaluation and assessment of the patient with hip pain. This article reviews the osseous, soft tissue, and vascular components of the hip and the normal anatomical variants encountered in routine hip imaging. Basic and advanced hip imaging is discussed with particular emphasis on radiographic and computed tomography measurements and their utility in evaluating patients with developmental hip dysplasia and femoroacetabular impingement syndrome.