The diagnostic value of direct CT arthrography using MDCT in the evaluation of acetabular labral tear: with arthroscopic correlation

CT Arthrography With Traction in Femoro-Acetabular Impingement: How to Do It?

Computed tomography arthrography (CTA) highly correlates with arthroscopy in detecting labral tears, especially in patients with positive impingement tests. CTA enables the acquisition of isotropic datasets with high spatial resolution within a single acquisition. However, the hip is a close-fitting, congruent, and nearly spherical joint, with relatively thin cartilage. We describe herein a simple and cost-effective method using traction for hip CTA, with axial manual distraction, that helps overcome the usual limitations, by widening the articular joint space and thus better delineating both acetabular and femoral cartilages.

ACR Appropriateness Criteria® Chronic Hip Pain: 2022 Update

Chronic hip pain is a frequent chief complaint for adult patients who present for evaluation in a variety of clinical practice settings. Following a targeted history and physical examination, imaging plays a vital role in elucidating the etiologies of a patient's symptoms, as a wide spectrum of pathological entities may cause chronic hip pain. Radiography is usually the appropriate initial imaging test following a clinical examination. Depending on the clinical picture, advanced cross-sectional imaging may be subsequently performed for further evaluation. This documents provides best practice for the imaging workup of chronic hip pain in patients presenting with a variety of clinical scenarios. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Diagnostic value of magnetic resonance imaging and magnetic resonance arthrography for assessing acetabular labral tears: A systematic review and meta-analysis

BACKGROUND

This study aimed to systematically evaluate the value of magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA) in the diagnosis of acetabular labral tears.

METHODS

Databases including PubMed, Embase, Cochrane Library, Web of Science, CBM, CNKI, WanFang Data, and VIP were electronically searched to collect relevant studies on magnetic resonance in the diagnosis of acetabular labral tears from inception to September 1, 2021. Two reviewers independently screened the literature, extracted data, and assessed the risk of bias in the included studies by using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. RevMan 5.3, Meta Disc 1.4, and Stata SE 15.0 were used to investigate the diagnostic value of magnetic resonance in patients with acetabular labral tears.

RESULTS

A total of 29 articles were included, involving 1385 participants and 1367 hips. The results of the meta-analysis showed that the pooled sensitivity, pooled specificity, pooled positive likelihood ratio, pooled negative likelihood ratio, pooled diagnostic odds ratio, area under the curve of the summary receiver operating characteristic, and Q* of MRI for diagnosing acetabular labral tears were 0.77 (95% confidence interval [CI], 0.75-0.80), 0.74 (95% CI, 0.68-0.80), 2.19 (95% CI, 1.76-2.73), 0.48 (95% CI, 0.36-0.65), 4.86 (95% CI, 3.44-6.86), 0.75, and 0.69, respectively. The pooled sensitivity, pooled specificity, pooled positive likelihood ratio, pooled negative likelihood ratio, pooled diagnostic odds ratio, area under the curve of the summary receiver operating characteristic, and Q* of MRA for diagnosing acetabular labral tears were 0.87 (95% CI, 0.84-0.89), 0.64 (95% CI, 0.57-0.71), 2.23 (95% CI, 1.57-3.16), 0.21 (95% CI, 0.16-0.27), 10.47 (95% CI, 7.09-15.48), 0.89, and 0.82, respectively.

CONCLUSION

MRI has high diagnostic efficacy for acetabular labral tears, and MRA has even higher diagnostic efficacy. Due to the limited quality and quantity of the included studies, the above results should be further validated.

3.0 T MRI is more recommended to detect acetabular labral tears than MR Arthrography: an updated meta-analysis of diagnostic accuracy

Background

This meta-analysis aimed to evaluate the current evidence on the diagnostic performance of MRI/MRA for detecting acetabular labral tears (ALT).

Methods

We systematically searched the PubMed, Embase, and Cochrane library until February 5, 2021, to identify original research studies reporting the diagnostic performance of MRI/MRA for the detection of ALT. Study methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. The summary sensitivity (Se) and specificity (Sp) of the studies were estimated using a bivariate model. We calculated the post-test probability to assess the clinical utility of MRI/MRA. Univariate meta-regression and subgroup analyses were performed to assess between-study heterogeneity.

Results

We included 22 studies (n = 1670 patients). The meta-analytic summary Se and Sp for MRI were 0.8 (95% CI 0.51–0.94) and 0.77 (95% CI 0.68–0.84), respectively, while for MRA they were 0.89 (95% CI 0.82–0.93) and 0.69 (95% CI 0.56–0.80). MRA showed a higher area under the summary receiver operating curve (SROC) (0.87 vs. 0.80) than MRI. MRI could increase the post-test probability to 0.78 and could decrease the post-test probability to 0.21, MRA could increase the post-test probability to 0.74 and could decrease the post-test probability to 0.14. Meta-regression analysis showed two significant factors affecting study heterogeneity: MR field strength and reference standard. After dividing the studies into two subgroups based on the MR field strength, we found that the Se values of 3.0 T MRI were very close to MRA (0.87 vs. 0.89), the Sp values of 3.0 T MRI were superior to MRA (0.77 vs. 0.69).

Conclusions

Given that 3.0 T MRI could provide a non-invasive, fast and convenient method to recognize suspicious ALT cases, 3.0 T MRI is more recommended than MRA.

Outcomes After Arthroscopic Repair in Patients With Tears of Hypertrophic Versus Morphologically Normal Acetabular Labra

BACKGROUND

Recently, a hypertrophic labrum has been reported in the absence of hip dysplasia, which can possibly contribute to an acetabular labral tear.

PURPOSE

To compare the clinical outcomes and complications, including the incidence of iatrogenic acetabular labrum and cartilage injury, in patients with tears of hypertrophic versus morphologically normal acetabular labra over a minimum follow-up period of 2 years and to assess the morphologic changes at follow-up computed tomography arthrography in the 2 groups.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Between January 2010 and December 2016, 20 patients (22 hips) with a hypertrophic labrum underwent arthroscopic hip surgery. A total of 22 patients (22 hips) without a hypertrophic labrum were assigned to the control group based on matching criteria, including age, sex, body mass index, labral tear, and labral repair. Clinical outcomes were assessed with the visual analog scale score, UCLA activity scale score (University of California, Los Angeles), and modified Harris Hip Score. Radiologic outcomes were assessed through serial radiography. Patients were followed for at least 2 years.

RESULTS

The mean age at surgery was 42 years. The most common cause of arthroscopic surgery in the study group was an isolated acetabular labral tear without any bony structural abnormalities (68.2%, 15 of 22 hips). All improvements in both groups were statistically significant at the last postoperative follow-up (P < .001). Although the radiologic and clinical outcomes were not significantly different between the groups, the complication rates, including iatrogenic labral perforations and cartilage injury, were significantly higher in patients with hypertrophic acetabular labral tears (9 vs 3, P = .042). The patient-reported satisfaction scores at the last postoperative follow-up were 8.4 and 7.9 in the study and control groups, respectively (P = .351).

CONCLUSION

The high rates of patient-reported satisfaction and the clinical outcomes after arthroscopic repair in both groups are encouraging. Arthroscopic treatment in patients with hypertrophic acetabular labral tears should be carefully performed to prevent iatrogenic injury during the surgery, and isolated hypertrophic labral tears can have good results after repair.

Location and Correlation of Acetabular Labral Tears and Paralabral Cysts Using Magnetic Resonance Imaging or Magnetic Resonance Arthrography in Patients With Femoroacetabular Impingement

PURPOSE

To evaluate the prevalence and location of paralabral cysts and the correlation between the type of femoroacetabular impingement (FAI) and acetabular labral tears, as well as the location of the paralabral cysts.

METHODS

Patients who received a diagnosis of FAI syndrome using plain radiography, magnetic resonance imaging or magnetic resonance arthrography, or computed tomographic arthrography from 2010 to 2015 were included in this study. The exclusion criteria were patients with arthritis (Tönnis grade 2 or greater) or dysplasia. We identified paralabral cysts and their location, size, configuration. Correlations between the type of FAI and labral tears and paralabral cysts were analyzed using the χ-square test.

RESULTS

Among 506 patients with FAI, paralabral cysts were found in 51 patients (55 hips) and were located anterosuperiorly in 40% of cases, posterosuperiorly in 36%, anteroinferiorly in 17%, and posteroinferiorly in 8%. We identified multilocular cysts in 60% of hips and unilocular cysts in 40%. Labral tears were radiographically found in 44 of 55 hips with paralabral cysts (80%); they were located anterosuperiorly in 59% and posterosuperiorly in 41%. Although paralabral cysts were found in the anteroinferior and posteroinferior areas, acetabular labral tears were not identified in the anteroinferior and posteroinferior areas. Classification of the type of FAI showed cam type in 14 of 55 hips (25.5%), pincer type in 16 (29%), mixed type in 7 (13%), labral tears in 15 (27%), and normal findings in 3 (5.5%). No correlation was found between the type of FAI and labral tears (P = .739) or the location of paralabral cysts (P = .228).

CONCLUSIONS

Paralabral cysts in patients with FAI most commonly are found in the anterosuperior area and are of the multilocular type. Although paralabral cysts in the anterosuperior and posterosuperior portions are related to labral tears, those in the anteroinferior and posteroinferior portions are not.

LEVEL OF EVIDENCE

Level IV, diagnostic case series.

Accuracy of Magnetic Resonance Imaging and Computed Tomography Arthrography in Diagnosing Acetabular Labral Tears and Chondral Lesions

Background

We investigated sensitivity, specificity, and accuracy of magnetic resonance imaging (MRI) and computed tomography arthrography (CTA), on the basis of arthroscopic findings, to diagnose acetabular labral tears and chondral lesions.

Methods

We retrospectively reviewed the results of MRI and subsequent CTA in 36 hips that underwent arthroscopic surgery (33 patients; 17 males [17 hips] and 16 females [19 hips]; average age, 35 years). All patients had positive impingement test results and groin pain. We analyzed sensitivity, specificity, and accuracy of MRI and CTA by comparing with the arthroscopic findings. Interobserver agreement and intraobserver reproducibility of the presence of tears and cartilage lesions on MRI and CTA were calculated using Kappa coefficients.

Results

The sensitivity, specificity, and accuracy of MRI for detection of acetabular labral tears by two observers were 60%, 80%, and 64%, respectively, and 65%, 70%, and 69%, respectively. The sensitivity, specificity, and accuracy of CTA for detection of labral tears by both observers were 85%, 90%, and 86%, respectively, and 92%, 80%, and 89%, respectively. However, the sensitivity and specificity of MRI for detection of acetabular chondral lesions by both observers were 36% and 84%, respectively, and 46% and 88%, respectively. The sensitivity and specificity of CTA for detecting acetabular cartilage lesions by both observers were 46% and 72%, respectively, and 64% and 72%, respectively. Intraobserver reproducibility for detection of labral tears and chondral lesions by using MRI was substantial (κ = 0.756 and κ = 0.693, respectively). Interobserver reliability for detection of labral tears and chondral lesions by using MRI was substantial (κ = 0.700 and κ = 0.875, respectively). Intraobserver reproducibility for detection of labral tears and chondral lesions by using CTA was substantial (κ = 0.832 and κ = 0.774, respectively). Interobserver reliability for detection of labral tears and chondral lesions by using CTA was high (κ = 0.886 and κ = 0.596, respectively).

Conclusions

This study demonstrated that the accuracy of MRI to detect an acetabular labral tear and a chondral lesion of the hip joint was not sufficient. CTA was reliable in the diagnosis of acetabular labral tears. However, both CTA and MRI were also of limited value to detect chondral lesions.

Factors Associated with the Risk of Articular Surface Perforation during Anchor Placement for Arthroscopic Acetabular Labral Repair

Background

The purpose of this study was to evaluate factors associated with the risk of articular surface perforation during anchor placement for arthroscopic acetabular labral repair using follow-up computed tomographic arthrography (CTA).

Methods

Forty-six patients (29 males and 17 females) underwent arthroscopic labral repair using 142 suture anchors (55 large anchors and 87 small anchors). The patients were followed with CTA 1 year postoperatively. Anchor position was assessed by the insertion angle and the distance of the suture anchor tip from the articular cartilage. The incidence of malposition of suture anchors was assessed in follow-up CTA. The location and incidence of malposition were compared between two groups divided according to the diameter of suture anchor.

Results

The mean insertion angle and distance were significantly different between the groups. Of the 142 anchors, 15 (11%) were placed in the cartilage-bone transitional zone. Articular involvement was most common at the 3 o'clock position of the suture anchor (six out of 33 anchors, 18.2%). Both the insertion angle and distance showed small values in the articular involvement group.

Conclusions

The radiographic analysis of the placement of suture anchors after arthroscopic labral refixation based on follow-up CTA demonstrates that articular involvement of anchors is related to the location on the acetabular rim (clock position) and anchor diameter.

Diagnostic Accuracy of Imaging Modalities and Injection Techniques for the Diagnosis of Femoroacetabular Impingement/Labral Tear: A Systematic Review With Meta-analysis

BACKGROUND

Diagnosing femoroacetabular impingement/acetabular labral tear (FAI/ALT) and subsequently making a decision regarding surgery are based primarily on diagnostic imaging and intra-articular hip joint injection techniques of unknown accuracy.

PURPOSE

Summarize and evaluate the diagnostic accuracy and clinical utility of various imaging modalities and injection techniques relevant to hip FAI/ALT.

STUDY DESIGN

Systematic review with meta-analysis.

METHODS

A computer-assisted literature search was conducted of MEDLINE, CINAHL, and EMBASE databases using keywords related to diagnostic accuracy of hip joint pathologic changes. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were used for the search and reporting phases of the study. Quality assessment of bias and applicability was conducted using the Quality of Diagnostic Accuracy Studies (QUADAS) tool. Random effects models were used to summarize sensitivities (SN), specificities (SP), likelihood ratios (+LR and -LR), diagnostic odds ratios (DOR), and respective confidence intervals (CI).

RESULTS

The search strategy and assessment for risk of bias revealed 25 articles scoring above 10/14 on the items of the QUADAS. Four studies investigated FAI, and the data were not pooled. Twenty articles on ALT qualified for meta-analysis. Pretest probability of ALT in the studies in this review was 81% (72%-88%), while the pretest probability of FAI diagnosis was 74% (95% CI, 51%-91%). The meta-analysis showed that computed tomography arthrography (CTA) demonstrated the strongest overall diagnostic accuracy: pooled SN 0.91 (95% CI, 0.83-0.96); SP 0.89 (95% CI, 0.74-0.97); +LR 6.28 (95% CI, 2.78-14.21); -LR 0.11 (95% CI, 0.06-0.21); and DOR 64.38 (95% CI, 19.17-216.21).

CONCLUSION

High pretest probability of disease was demonstrated. Positive imaging findings increased the probability that a labral tear existed by a minimal to small degree with the use of magnetic resonance imaging/magnetic resonance angiogram (MRI/MRA) and ultrasound (US) and by a moderate degree for CTA. Negative imaging findings decreased the probability that a labral tear existed by a minimal degree with the use of MRI and US, a small to moderate degree with MRA, and a moderate degree with CTA.

CLINICAL RELEVANCE

Although findings of the included studies suggested potentially favorable use of these modalities for the diagnosis of ALT and FAI, our results suggest that these findings have limited generalizability and clinical utility given very high pretest prevalence, large confidence intervals, and selection criteria of the studies. Registration: PROSPERO Registration #CRD42015027745.

No difference in prevalence of radiographic subspinal impingement of the hip between symptomatic and asymptomatic subjects

PURPOSE

The study determined the prevalence of subspinal impingement (SSI) in symptomatic and asymptomatic individuals, morphologic characteristics in symptomatic patients, and risk factors for SSI.

METHODS

The study cohort consisted of 427 patients (427 hips; median age 33.4 years; range 19-50 years) with mechanical symptoms who underwent multi-detector computed tomography arthrography (symptomatic patients) and 259 control (asymptomatic) patients who underwent abdominopelvic three-dimensional CT because of a ureter stone or minor trauma. Two orthopaedic surgeons reviewed the images to evaluate the prevalence of SSI and the relationship with morphologic abnormalities. Radiologic parameters were further compared between the SSI and non-SSI groups in symptomatic patients using the Chi-squared test or two-sample t test. Variables with p values <0.10 (sex and age) were included in the multi-variate analysis. Logistic regression analysis was carried out to identify independent risk factors for SSI.

RESULTS

The prevalence of SSI in symptomatic and asymptomatic patients was 65/427 (15.2%) and 40/259 (15.4%), respectively (n.s.). Structural bony abnormalities in symptomatic patients were not associated with the presence of SSI (n.s.). Binary logistic regression analysis revealed that youth (odds ratio 0.952, 95% CI 0.922-0.984) was the only significant factor for SSI.

CONCLUSIONS

SSI had a similar prevalence in symptomatic and asymptomatic patients and was not rare in either group. Therefore, clinical implication of SSI in symptomatic patient should be re-evaluated through further study.

LEVEL OF EVIDENCE

Level IV.

Prevalence and clinical significance of hypertrophic labrum in non-dysplastic hips

BACKGROUND

Hypertrophic labrum in dysplastic hip has been frequently reported and is known as limbus in developmental dysplasia of the hip. However, hypertrophic labrum without hip dysplasia has not been reported to date. The purpose of this study was to define hypertrophic labrum and to investigate the prevalence and clinical significance of an abnormally hypertrophic labrum in non-dysplastic hips.

METHODS

Between 2007 and 2014, direct CT arthrography was performed in 464 patients (470 hips) who had chronic groin pain and positive impingement or Faber test. There were 189 male (192 hips) and 275 female (278 hips) patients. The mean age was 46.8 years (range, 16-74 years). The hypertrophic labrum was defined as a labrum wider than two standard deviations away from the mean. Surgical correlation of hypertrophic labrum was obtained in cases with hip arthroscopy by a single surgeon.

RESULTS

Seventeen hips (3.6%) were found to have a hypertrophic labrum which had a mean width of 11.2 mm (±1.1) (range, 9.8-14.1 mm). The average width (±SD) of the labrum without hypertrophy was 5.5 mm (±2.4) (range, 2-9.8 mm). Arthroscopic findings of the hypertrophic labrum included fissure and longitudinal tear at the chondrolabral junction and they were associated with chondral abnormality adjacent to the lesion.

CONCLUSIONS

Hypertrophic labrum without hip dysplasia is not rare with a high incidence of tears. Care should be taken during arthroscopic access to the hip joint in patients with this morphologic variation as iatrogenic damage can occur more easily.

LEVEL OF EVIDENCE

Case Series; Level IV.

Morphologic Changes and Outcomes After Arthroscopic Acetabular Labral Repair Evaluated Using Postoperative Computed Tomography Arthrography

PURPOSE

To investigate smaller sized labra after acetabular labral repair comparing preoperative and postoperative computed tomography arthrography (CTA) and to assess the correlation between the anatomic changes and clinical outcomes.

METHODS

The design and protocol of this retrospective study were approved by the institutional review board of our hospital. The inclusion criteria included age older than 18 years and hip pain associated with mechanical symptoms. Patients with previous hip surgery, avascular necrosis, rheumatologic disorders, or advanced arthritis were excluded. All tears with femoroacetabular impingement were treated with bumpectomy or acetabuloplasty and repaired using arthroscopic suture anchors. We evaluated clinical outcomes using the modified Harris Hip Score (mHHS) and the morphologic changes and radiologic outcomes (labral retear and leakage of dye) using CTA at a minimum 2-year follow-up. The paired t test was performed to detect changes in labral height, labral width, and mHHS.

RESULTS

Forty labral tears in 40 patients (mean age, 32.1 ± 9.2 years) underwent labral repair, with femoroplasty in 20 hips and acetabuloplasty in 17 hips, and no patients required capsular repair after capsulotomy. No leakage of contrast dye was detected during the follow-up CTA procedure. No labral retears were observed after labral refixation at the postoperative CTA evaluation. However, the mean width and height of the labrum changed from 8.1 mm and 4.9 mm, respectively, preoperatively to 6.7 mm and 4.4 mm, respectively, at the postoperative follow-up (decreasing by 19% and 11%, respectively; both P < .001). In addition, the mean mHHS for the 36 patients in the complete repair group improved from 61 ± 16.0 to 90 ± 9.6 (P = .01). Four hips showed incomplete repairs.

CONCLUSIONS

Repaired labra are well maintained after capsulotomy based on follow-up CTA after arthroscopic labral repair. In addition, decreased height and width of the labra do not affect the clinical outcomes.

LEVEL OF EVIDENCE

Level IV, therapeutic study (case series [no, or historical, control group]).

Posterior, Lateral, and Anterior Hip Pain Due to Musculoskeletal Origin: A Narrative Literature Review of History, Physical Examination, and Diagnostic Imaging

OBJECTIVE

The purpose of this study was to present a narrative review of the literature of musculoskeletal causes of adult hip pain, with special attention to history, physical examination, and diagnostic imaging.

METHODS

A narrative review of the English medical literature was performed by using the search terms "hip pain" AND "anterior," "lateral," and "posterior." Additionally, specific entities of hip pain or pain referral sources to the hip were searched for. We used the PubMed search engine through January 15, 2016.

RESULTS

Musculoskeletal sources of adult hip pain can be divided into posterior, lateral, and anterior categories. For posterior hip pain, select considerations include lumbar spine and femoroacetabular joint referral, sacroiliac joint pathology, piriformis syndrome, and proximal hamstring tendinopathy. Gluteal tendinopathy and iliotibial band thickening are the most common causes of lateral hip pain. Anterior hip pain is further divided into causes that are intra-articular (ie, labral tear, osteoarthritis, osteonecrosis) and extra-articular (ie, snapping hip and inguinal disruption [athletic pubalgia]). Entrapment neuropathies and myofascial pain should also be considered in each compartment. A limited number of historical features and physical examination tests for evaluation of adult hip pain are supported by the literature and are discussed in this article. Depending on the clinical differential, the gamut of diagnostic imaging modalities recommended for accurate diagnosis include plain film radiography, computed tomography, magnetic resonance imaging, skeletal scintigraphy, and ultrasonography.

CONCLUSIONS

The evaluation of adult hip pain is challenging. Clinicians should consider posterior, lateral, and anterior sources of pain while keeping in mind that these may overlap.

MDCT arthrography of the hip: value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction

OBJECTIVE

The purpose of this article is to assess the effect of the adaptive statistical iterative reconstruction (ASIR) technique on image quality in hip MDCT arthrography and to evaluate its potential for reducing radiation dose.

SUBJECTS AND METHODS

Thirty-seven patients examined with hip MDCT arthrography were prospectively randomized into three different protocols: one with a regular dose (volume CT dose index [CTDIvol], 38.4 mGy) and two with a reduced dose (CTDIvol, 24.6 or 15.4 mGy). Images were reconstructed using filtered back projection (FBP) and four increasing percentages of ASIR (30%, 50%, 70%, and 90%). Image noise and contrast-to-noise ratio (CNR) were measured. Two musculoskeletal radiologists independently evaluated several anatomic structures and image quality parameters using a 4-point scale. They also jointly assessed acetabular labrum tears and articular cartilage lesions.

RESULTS

With decreasing radiation dose level, image noise statistically significantly increased (p=0.0009) and CNR statistically significantly decreased (p=0.001). We also found a statistically significant reduction in noise (p=0.0001) and increase in CNR (p≤0.003) with increasing percentage of ASIR; in addition, we noted statistically significant increases in image quality scores for the labrum and cartilage, subchondral bone, overall diagnostic quality (up to 50% ASIR), and subjective noise (p≤0.04), and statistically significant reductions for the trabecular bone and muscles (p≤0.03). Regardless of the radiation dose level, there were no statistically significant differences in the detection and characterization of labral tears (n=24; p=1) and cartilage lesions (n=40; p≥0.89) depending on the ASIR percentage.

CONCLUSION

The use of up to 50% ASIR in hip MDCT arthrography helps to reduce radiation dose by approximately 35-60%, while maintaining diagnostic image quality comparable to that of a regular-dose protocol using FBP.

Strategy and optimization of diagnostic imaging in painful hip in adults

Diagnostic imaging strategy in painful hip depends on many factors, but in all cases, plain X-ray is the first investigation. It may be sufficient to reach diagnosis and determine treatment options. More effective but more expensive exploration is indicated in two circumstances: when plain X-ray is non-contributive, and when diagnosis has been established but more accurate imaging assessment is needed to guide treatment. Following radiography, the choice of imaging techniques depends not only on the suspected pathology but also on the availability of equipment and its performance. MRI is probably the technique that provides the most comprehensive results; recent improved accessibility has significantly simplified the diagnostic algorithm. CT remains invaluable, and current techniques have reduced patient irradiation to a level similar to that of standard X-ray. Finally, cost is an important consideration in choosing the means of exploration, but the overall financial impact of the various strategies for diagnosis of painful hip is not well established. This article aims to provide a simple and effective diagnostic strategy for the assessment of painful hip, taking account of the clinical situation, and to detail the most typical semiologic patterns of each disease affecting this joint.

The role of imaging in early hip OA

Hip osteoarthritis (OA) is characterized by cartilage degradation, subchondral bone sclerosis and osteophyte formation. Nowadays, OA is thought to develop via different etiologies that all lead to a similar form of end stage joint degradation. One of these subtypes is related to an abnormal shaped hip joint, like acetabular dysplasia and a cam deformity. These bony abnormalities are highly predictive for development of hip OA, but they are likely to already be present from childhood. This suggests that these deformations induce OA changes in the hip, well before extensive hip degradation becomes present three to four decades later. Accurate detection and successful characterization of these early OA events might lead to better treatment options for hip OA besides nowadays available invasive joint replacement surgery. However, current diagnostic imaging techniques like radiographs or plain magnetic resonance imaging (MRI), are not sensitive enough to detect these subtle early OA changes. Nor are they able to disentangle intertwined and overlapping cascades from different OA subtypes, and neither can they predict OA progression. New and more sensitive imaging techniques might enable us to detect first OA changes on a cellular level, providing us with new opportunities for early intervention. In this respect, shape analysis using radiography, MRI, computed tomography (CT), single photon emission computed tomography (SPECT)/CT, and positron emission tomography (PET) might prove promising techniques and be more suited to detect early pathological changes in the hip joint. A broad application of these techniques might give us more understanding what can be considered physiological adaptation of the hip, or when early OA really starts. With a more clear definition of early OA, more homogenous patient populations can be selected and help with the development of new disease modifying OA interventions.

Optimization of computed tomography (CT) arthrography of hip for the visualization of cartilage: an in vitro study

OBJECTIVE

We sought to optimize the kilovoltage, tube current, and the radiation dose of computed tomographic arthrography of the hip joint using in vitro methods.

MATERIALS AND METHODS

A phantom was prepared using a left femoral head harvested from a patient undergoing total hip arthroplasty and packed in a condom filled with iodinated contrast. The right hip joint of a cadaver was also injected with iodinated contrast. The phantom and the cadaver were scanned using different values of peak kilovoltage (kVp) and tube current (milliamp seconds, mAs). Three different regions of interest (ROI) were drawn in the cartilage, subchondral bone plate, and intraarticular contrast. The attenuation values, contrast/noise ratio (CNR), and effective dose were calculated. Two independent observers classified the quality of the contrast-cartilage interface and the cartilage-subchondral bone plate interface as (1) diagnostic quality or (2) nondiagnostic quality.

RESULTS

Contrast, cartilage, and subchondral bone plate attenuation values decreased at higher kVp. CNR increased with both kVp and mAs. The qualitative analysis showed that in both phantom and cadaver, at 120 kVp and 50 mAs, the contrast-cartilage and cartilage-subchondral bone plate interfaces were of diagnostic quality, with an effective dose decreased to 0.5 MSv.

CONCLUSIONS

The absolute effective dose is not directly related to the quality of images but to the specific combination of kVp and mAs used for image acquisition. The combination of 120 kVp and 50 mAs can be suggested to decrease the dose without adversely affect the visibility of cartilage and subchondral bone plate.

Diagnostic value of ultrasound and computed tomographic arthrography in diagnosing anterosuperior acetabular labral tears

PURPOSE

This study investigated the sensitivity, specificity, and accuracy of ultrasound as well as the computed tomography arthrography (CTA) findings and arthroscopic findings for the diagnosis of anterosuperior acetabular tear and correlated tear types using the Lage classification system on ultrasound and CTA compared with the arthroscopic findings.

METHODS

We retrospectively reviewed the results of ultrasonographic examinations conducted before injection and after injection of contrast for subsequent CTA in 36 hips (34 patients; 24 men [71%] and 10 women [29%]; mean age, 36 years). All patients had chronic groin pain and a positive impingement test. We analyzed the sensitivity, specificity, and accuracy before injection, after injection, and at CTA and compared these with findings with the arthroscopic findings. Interobserver agreement and intraobserver reproducibility of the presence of a tear and tear type in the anterosuperior quadrant of the acetabular labrum on ultrasonography and CTA were calculated by use of κ coefficients.

RESULTS

The sensitivity, specificity, and accuracy for sonographic detection of labral tear before injection/after injection were 58%/79%, 67%/58%, and 61%/72%, respectively, for observer 1 and 75%/92%, 25%/42%, and 58%/75%, respectively, for observer 2. The sensitivity, specificity, and accuracy for CTA detection of labral tears were 96%, 92%, and 94%, respectively, for observer 1 and 88%, 92%, and 89%, respectively, for observer 2. When the sonographic classification was compared with the arthroscopic findings of observer 1 and observer 2, the accuracy before injection/after injection was only 53%/67% and 58%/75%, respectively. The accuracy of morphologic classification of CTA and arthroscopic findings of observer 1 and observer 2 was 83% and 75%, respectively. Interobserver correlation before injection and at CTA was poor (κ = 0.056) and moderate (κ = 0.642), respectively.

CONCLUSIONS

Although intra-articular injection during sonographic examination could improve diagnosis of labral tears, sonographic examination as a diagnostic technique is still of limited use. However, CTA shows reliable validity in the diagnosis of acetabular labral tears.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.