MR Arthrography Research Articles

Pathology and surgical outcomes of unstable painful shoulders.

BackgroundBoileau et al have reported on the unstable, painful shoulder (UPS), which was defined as painful shoulders without any recognized anteroinferior subluxations or dislocations that were associated with roll-over lesions (ie, instability lesions) on imaging or at arthroscopy. However, they included various pathologies, probably due to the ambiguity in their definitions of UPS. We redefined UPS as follows: (1) shoulder pain during daily or sports activities, (2) traumatic onset, (3) no complaint of shoulder instability, and (4) soft-tissue or bony lesions, such as Bankart or humeral avulsion of glenohumeral ligament lesion, confirmed by arthroscopy. The purpose of this study was to retrospectively investigate pathologies of UPS based on our definitions. We also aimed to assess the outcomes after arthroscopic soft-tissue stabilization for UPS.MethodsWe reviewed patients who were retrospectively diagnosed as UPS based on our definition and underwent arthroscopic stabilization between January 2007 and September 2018. Patients’ demographics, physical and radiographic findings, intraoperative findings, clinical outcomes (Rowe scores, Subjective Shoulder Value [SSV], and the visual analog scale [VAS] for pain), and return to play sport (RTPS) were investigated.ResultsThis study included 91 shoulders in 91 patients with a mean age of 23 years (range, 15-51). The mean follow-up was 37 months (range, 24-156). Eighty-seven patients were involved in sports activities: collision/contact, 55 patients (60%); overhead, 26 patients (29%). The pain was reproduced during the anterior apprehension test in 86 shoulders (95%). Normal type (49%) predominated in glenoid morphology followed by fragment (bony Bankart) type (37%). Most fragment-type lesions were seen in collision/contact athletes. Intraoperative findings demonstrated that Bankart lesions were found in all patients and Hill-Sachs lesions only in 42%. Magnetic resonance arthrography in the abducted and externally rotated positions showed a Bankart lesion in 76 shoulders (84%). Rowe score, SSV, and pain VAS significantly improved postoperatively (P < .001 for each). Forty-two of 70 athletes (60 %) with > 2-year follow-up returned to the sport at a complete or near-preinjury level. Six (9%) athletes experienced reinjury.ConclusionAll shoulders that were diagnosed as UPS with our definition had a Bankart lesion. There seemed to be two different types of pathologies: Bankart lesions in lax shoulders and bony Bankart lesions in collision/contact athletes. The pain experienced during the anterior apprehension test may be useful for the diagnosis of UPS. Arthroscopic soft-tissue stabilization yielded good clinical outcomes with a high RTPS rate, but the reinjury rate was relatively high.

Diagnostic performance of MRA in abduction and external rotation position in the detection of glenoid labral lesions: a systematic review and meta-analysis.

To compare the diagnostic performance of direct magnetic resonance arthrography (MRA) for labral lesions during conventional, abduction and external rotation (ABER), conventional plus abduction, and external rotation (ABER) positioning by using a systematic review and meta-analysis. A comprehensive literature search was performed on the two main concepts of magnetic resonance arthrography: extremity position and labral lesions. Inclusion criteria consisted of original studies that assessed the diagnostic accuracy of MR arthrography in ABER and conventional position alone or combined for the diagnosis of labral lesions by using surgical findings as the reference standard. Meta-analyses were performed that compared MR arthrography during conventional positioning, ABER, and conventional plus ABER positioning. Nine studies met the inclusion and exclusion criteria. A total of 733, 504, and 313 lesions assessed by conventional MRA, ABER MRA, and conventional plus ABER MRA, respectively, were included in our analysis. Pooled sensitivities of MRA in conventional, ABER, and conventional plus ABER position for labral tear diagnosis were 81.5%, 81.6%, and 95.7%, respectively. Pooled specificities of MRA in conventional, ABER, and conventional plus ABER position for labral tear diagnosis were 88.8%, 85.6%, and 94.5%, respectively. Summary receiver operator characteristic (ROC) curve demonstrated improved accuracy of conventional plus ABER MRA compared with conventional MRA or ABER MRA with the area under the curve (AUC) of 0.99, 0.90, and 0.88, respectively. Conventional plus ABER MRA showed increased diagnostic accuracy compared to both ABER MRA and conventional MRA alone in the diagnosis of labral lesions.

Comparison of conventional MRI, MR arthrography, MR arthrography with traction, MR arthrography with pressure in the evaluation of articular distension

ObjectiveTo evaluate the performance of conventional MRI, standard MR arthrography, MR arthrography with traction and MR arthrography with pressure in articular distension in patients with ACL injury. Design and patientsThe consecutive patients (7 female, 21 male) with acute ACL injured conventional MRI, MR arthrography, MR arthrography with traction and MR arthrography with pressure were evaluated. ResultsThe amount of distension in the joint was evaluated in the posterior, femorotibial and anterior compartments. Medially, between the meniscus posterior horn and the tibial corner, MRA with pressure was found to be more effective in showing this distance than MRA with traction (p < 0,05). Laterally, in measurements made between the posterior horn of the meniscus and the capsule, MRA with traction and MRA with pressure are more effective showing this distance than conventional MRI and standard MRA (p < 0,05). In measurements made medially, between the posterior horn of the meniscus and the capsule, MRA with traction is more effective in showing this distance than standard MRA (p < 0,05). In all three different MRA modalities, the lateral femorotibial joint distance was found to be statistically higher than conventional MRI (p < 0,05). Medial femorotibial joint distance was found to be statistically higher in MRA with pressure than in conventional MRI and standard MRA (p < 0,05). The medial infrapatellar distance was found to be statistically higher in MRA with pressure than standard MRA and MRA with traction (p < 0,05). The lateral infrapatellar distance is higher in MRA with pressure than in MRA with traction, and this height is statistically significant (p < 0,05). ConclusionTraction and pressure applications added to MRA will increase the effectiveness of the method by increasing the distension in the knee joint. Although both seem to be effective in creating distension in posterior compartment and femorotibial joint distance, MRA with pressure is more effective especially in anterior compartment.

Hip Microinstability: Understanding a Newly Defined Hip Pathology in Young Athletes

Microinstability is an increasingly recognized diagnosis in young athletes presenting with hip pain. Causes of microinstability may include abnormality of the hip bony anatomy, acetabular labral tears, joint capsule laxity or injury, and muscle dysfunction. Borderline hip dysplasia is an increasingly recognized factor predisposing to microinstability. The capsuloligamentous structures of the hip, particularly the iliofemoral ligament, provide important restraints to femoral head motion, and iatrogenic defects can predispose patients to instability after surgery. Injury to the acetabular labrum may disrupt its important hip-stabilizing properties including the suction seal and improved acetabular depth. Hip muscle weakness or imbalance may result in increased femoral head motion within the acetabulum. The diagnosis of hip microinstability can be challenging, and the history is often nonspecific. Physical examination maneuvers include the anterior apprehension, prone instability, axial distraction, and abduction-hyperextension-external rotation tests. Radiographic features may include borderline hip dysplasia, femoral head-neck junction cliff sign, and an elevated femoral-epiphyseal acetabular roof index. Magnetic resonance arthrography may demonstrate a capsular defect, capsular thinning, or labral pathology. Diagnostic intra-articular injection of anesthetic can confirm the intra-articular nature of the pathology. Management of hip microinstability focuses on strengthening the dynamic stabilizers of the hip through focused physical therapy. Surgery may be considered in recalcitrant cases where symptoms persist despite optimization of hip stabilizer strength. In such cases, addressing the primary source of instability through labral repair or reconstruction and capsular repair or plication can be considered. In highly selected cases, surgery can result in excellent outcomes.

COMPARATIVE RADIOLOGICAL DIAGNOSTICS OF ACUTE TRIANGULAR FIBROCARTILAGE COMPLEX INJURIES.

The aim was to analyze patients with clinical diagnosis of triangular fibrocartilage complex (TFCC) lesion using standard x-ray, ultrasound, conventional magnetic resonance imaging (MRI) and MR arthrography (MRA); to evaluate the accuracy of MRA compared with MRI in the diagnosis of this lesion; and to evaluate ultrasound as a method of diagnosing TFCC lesion. We analyzed 72 patients (46 female and 26 male; age range, 22-61 years; mean age 37 years; 50 right and 22 left wrists) with suspected TFCC lesion with clinical examination, standard x-rays, and ultrasound. We confirmed patients with traumatic TFCC injury on MRI and MRA. Ultrasound found 13 lesions in 72 patients with suspected TFCC lesions. Conventional MRI found 66 and MRA 68 TFCC lesions. Ultrasound is useful for visualizing intra-articular effusion, soft tissue, bone surface, and for early detection of occult fractures. MRI is a better diagnostic modality, fully able to visualize the TFCC cartilage and ligaments. MRA is consistently and accurately able to visualize structural abnormalities of TFCC.

MRI and MR Arthrography Imaging of the Pathologies of the Wrist: A Pictorial Essay

Magnetic Resonance Imaging (MRI) has a special advantage over radiographs and Computed Tomography (CT) in evaluating an anatomically complex structure like wrist, owing to its excellent soft-tissue resolution and multiplanar imaging functionality. MR arthrography further improves the diagnostic value of MRI by virtue of its meticulous depiction of even small tears involving the Triangular Fibrocartilage Complex (TFCC), intrinsic and extrinsic ligaments of the wrist. This article focuses on the MRI and MR arthrography illustration of various traumatic as well as non traumatic pathologies affecting the wrist region and is mainly intended to educate the residents by comprehensively reviewing the imaging features of the major afflictions of this complex joint in a systematic fashion using checklists.

Diagnostic Effectiveness of MDCT arthrography in preoperative planning of anterior shoulder instability: A comparative study with MR arthrography and arthroscopy

Diagnostic Effectiveness of MDCT arthrography in preoperative planning of anterior shoulder instability: A comparative study with MR arthrography and arthroscopy

Instrumental Diagnosis and Preoperative Planning of Hip Arthroscopy in Femoroacetabular Impingement Syndrome: Lecture

Femoroacetabular impingement syndrome (FAI) is essentially a mechanical conflict that occurs when the acetabulum edge of the pelvic bone interacts with femur head and neck with clinical symptoms. In a basis of this conflict, as a rule, is a single or bilateral anatomical bone defect that causes an irregular shape of the hip joint with congenital or acquired etiology. Radiography, performed in a direct projection and in 45 Dunn position with external rotation of 40, is traditionally considered as basic tool for the radiological diagnosis of hip joint pathology. It allows to assess the anatomical and morphological structure of joint surfaces and their relationship. Detection of severe hip deformations may require computed tomography (CT). Magnetic resonance imaging (MRI) or magnetic resonance arthrography (MRA) is used to assess the condition of soft tissue structures of hip joint, its damage is often found in patients with FAI. The modern method of treating patients with FAI is hip arthroscopy, the undeniable advantage of which is low traumatic nature of the operation, low level of intraoperative complications and short postoperative rehabilitation period. For its successful implementation, it is necessary to take into account the complexity of performing hip arthroscopy, its duration, the necessity for good technical equipment and a high skill level of the operating surgeon. However, this operation has a number of limitations, which must be taken into account when selecting patients.

The distribution in joint recesses and adjacent synovial compartments of loose bodies determined on MR and CT arthrographies of ankle joint.

Loose bodies (LBs) are intraarticular free bodies and may cause synovial inflammation.Accurate and complete determination of the number and location of LBs before surgery are very important for effective treatment.The location, number and distribution of LBs in the ankle joint may be determined successfully by high-resolution magnetic resonance arthrography (MRA) and computed tomography arthrography (CTA).For this purpose, MRA and CTA may increase the diagnostic and therapeutic success of the arthroscopy.

Evaluation of Transverse Acetabular Ligament Assessment due to Acetabular Labral Tear in Patients Undergoing Magnetic Resonance Arthrography

Evaluation of Transverse Acetabular Ligament Assessment due to Acetabular Labral Tear in Patients Undergoing Magnetic Resonance Arthrography

An assessment of SLAP type 5 lesions using proton density oblique sagittal imaging in magnetic resonance arthrography.

Bankart lesions accompany superior labrum anteroposterior (SLAP) lesions; these are called SLAP type 5. To compare SLAP type 5 lesions using routine magnetic resonance arthrography (MRA) and thin-slice oblique sagittal proton density (PDW) sequences and correlation operation results. In total, 181 patients were admitted with shoulder instability. The study was completed with 44 patients. The presence or absence of isolated Bankart and SLAP type 5 lesions in routine MRA and PDW oblique sagittal images were evaluated separately. Absence of rupture scored 0 points, suspected ruptures scored 1 point, and apparent ruptures scored 2 points. The two scores were compared with the shoulder arthroscopy findings. According to the findings in the shoulder arthroscopy, 40 patients had Bankart lesions and 17 patients had accompanying SLAP type 5 lesions. To detect a Bankart lesion, there was no significant difference between routine MRA sequences and PDW oblique sagittal images (P = 0.061). Routine MRA sensitivity was 95%, specificity 25%, positive predictive value (PPV) 92%, negative predictive value (NPV) 33%, while for PDW oblique sagittal images, sensitivity was 75%, specificity 100%, PPV 100%, and NPV 28.5%. In 8/17 type 5 SLAP lesions, routine MRA detected sensitivity 47%, specificity 92.6%, PPV 80%, and NPV 73.5%; in 14/17 SLAP type 5 lesions, PDW oblique sagittal images detected sensitivity 82%, specificity 100%, PPV 100%, and NPV 90% (P = 0.015). The PDW oblique sagittal images may play a significant role in assessing the anterior and superior extent of the tears.

MR arthrography of the shoulder; correlation with arthroscopy.

BackgroundShoulder dislocation is a common injury, particularly in the younger population. Common long-term sequelae include pain, recurrence, and shoulder arthritis. Immediate and correct diagnosis following shoulder dislocation is key to achieving optimum outcomes. Although magnetic resonance arthrography (MRA) is frequently used for diagnosing shoulder instabilities, arthroscopy is still considered the gold standard.PurposeThis study aims to compare the diagnostic value of arthroscopy and MRA of the shoulder joint.Materials and methodsThis retrospective study estimates the sensitivity and specificity of MRA of the shoulder. Data from patients who had undergone shoulder MRA and subsequent arthroscopy during a 5-year period were retrospectively collected. Sensitivity and specificity were calculated using the arthroscopic findings as the gold standard. Moreover, diagnostic accuracy was estimated using McNemar’s test.ResultsIn total, 205 cases were included from which 372 pathological findings were uncovered during the arthroscopic procedures as opposed to 360 findings diagnosed from the MRA images. The glenoid labral tear was the most common finding reported by MRA and arthroscopy. For the detection of glenoid labral tears on MRA, the sensitivity was 0.955 but with eight missed lesions; the specificity was 0.679. Capsular tears, rotator cuff tears, and cartilage lesions proved the most difficult to correctly diagnose using MRA with sensitivities of 0.2, 0.346, and 0.366, respectively.ConclusionsWith a sensitivity of 95%, MRA is a valuable diagnostic tool for assessing shoulder instabilities, particularly when diagnosing labral lesions, including bony and soft-tissue Bankart lesions. Sensitivities and specificities for other glenohumeral lesions are less convincing, however.

Three-Dimensional Magnetic Resonance Arthrography of Post-Arthroscopy Hip Instability Demonstrates Increased Effective Intracapsular Volume and Anterosuperior Capsular Changes

PurposeTo quantify the magnetic resonance arthrography (MRA) capsular morphologic findings associated with postarthroscopy hip instability.MethodsAmong patients with clinically significant iatrogenic hip instability at a single center, patients with preindex and postindex surgery MRAs were identified. These MRAs were compared regarding effective intracapsular volume calculated by semi-automated 3-dimensional pixel intensity region segmentation, 2-dimensional anterior proximal intracapsular area in the femoral neck axial plane reconstruction, maximal anterior fluid pocket depth, capsule retraction distance, and capsular instability grade. Morphological measurements were conducted using Horos image processing software. Paired t-test, paired Wilcoxon signed rank test, and the McNemar test were used for identifying statistical significance.ResultsIn 42 patients, mean effective intracapsular volume was significantly greater in the postindex surgery MRAs (19.44 cm3 vs 17.26 cm3; P = .006). Proximal anterosuperior (12-3 o'clock) intracapsular area was also significantly greater after index surgery (2.84 cm2 vs 1.43 cm2; P < .001. Proximal anteroinferior (3-6 o'clock) intracapsular area (1.34 cm2 vs 0.97 cm2; P = .002), capsule deficiency grade (P < .001), anterior capsule retraction distance (4.83 mm vs 0.34 mm; P < .001), and maximum anterior fluid depth (8.33 mm vs 4.90 mm; P <.001) were also significantly increased after index surgery.ConclusionIn comparison to the preoperative state, iatrogenic hip instability is associated with MRA findings that include increases in total effective intracapsular volume, proximal anterosuperior and anteroinferior intracapsular cross-sectional area, maximum proximal anterosuperior fluid depth, and capsule retraction distance.Level of EvidenceLevel IV, diagnostic case series.

Calcific Tendinosis Reduces Diagnostic Performance of Magnetic Resonance Imaging in the Detection of Rotator Cuff Tears

This study aimed to investigate the effect of calcific tendinosis on the diagnosis of rotator cuff tears (RCTs) on magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA). Calcific tendinosis was confirmed radiographically. Two musculoskeletal radiologists then retrospectively and independently reviewed the MRI/MRA examinations, with surgery or arthroscopy performed within 90 days of the MRI. Rotator cuffs were categorized as no tear, partial-thickness tear, and full-thickness tear. Partial-thickness tear/full-thickness tear groups were combined for analysis. Forty-eight MRI (mean age, 63.4 years; range, 37-83 years; female-to-male ratio, 29:19) and 7 MRA (mean age, 49.2 years; range, 25-60 years; female-to-male ratio, 4:3) patients were included. Reader 1 and reader 2 sensitivity/specificity values for RCTs on MRI were 95%/50% and 89%/30%, and the values on MRA were 100%/67% and 100%/100%, respectively. Overall agreement was present in 87% (48 of 55; κ = 0.55 [95% confidence interval, 0.26-0.85]). Magnetic resonance imaging has decreased specificity in diagnosing RCTs when calcific tendinosis is present. Magnetic resonance arthrography performed better in this population and could be considered.

The Evolving Roles of MRI and Ultrasound in First-Line Imaging of Rotator Cuff Injuries.

Rotator cuff tears are the most likely source of shoulder pain in adults and may cause protracted disability. Management of rotator cuff tears is associated with considerable costs. Accurate diagnosis can guide surgical planning and help achieve a favorable clinical outcome. Although radiography remains the initial imaging test for shoulder injury, the roles of MRI and ultrasound (US) as first-line imaging after radiography are evolving. This article leverages current literature and the practical experience of subspecialty musculoskeletal radiologists from different institutions in describing a practical approach to imaging rotator cuff pathology. Both MRI and US are accurate for identifying rotator cuff tears, but each has advantages and shortcomings. As both modalities currently represent reasonable first-line approaches, considerable practice variation has evolved. Given the low cost of US, imagers should strive to optimize the quality of shoulder US examinations and to build referrer confidence in this modality. The roles of direct CT and MR arthrography as well as imaging evaluation of the postoperative rotator cuff are also considered. Through careful selection among the available imaging modalities and optimal performance and interpretation of such examinations, radiologists can positively contribute to the diagnosis and treatment of patients with rotator cuff injuries.

Magnetic Resonance Arthrography of the Wrist: The Impact on Operative Management of Wrist Injuries.

Background There is no consensus on the utility of arthrography in the evaluation of wrist injuries. This study evaluates ordering trends of different types of magnetic resonance imaging (MRI) of the wrist and compares rates of surgery following these imaging modalities. Methods A national claims-based database was used to identify patients who underwent MRI within 90 days of a first-instance diagnosis of wrist injury from 2010 to 2018. The utilization of MRI without intravenous (IV) contrast, MRI with IV contrast, and MRI with arthrogram was investigated. The instances of operative procedures of the wrist within 1 year of MRI study were recorded. Patient demographics, comorbidities, type of operative procedure, and ordering physician specialty were obtained. Logistic regression analysis was used to evaluate the utilization of MRI and subsequent 1-year operative intervention rates as well as association of patient-related factors. Results Magnetic resonance arthrography use was associated with higher rates of subsequent operative treatment. Surgeons were more likely to order an arthrogram at the time of MRI. Younger patients were more likely to undergo MRI-based advanced imaging. Conclusion Surgeons may perceive MRA of the wrist to play an important role in operative decision-making following wrist injury. Level of Evidence This is a Level III, retrospective cohort study.

Evaluation of CT-Guided Ultra-Low-Dose Protocol for Injection Guidance in Preparation of MR-Arthrography of the Shoulder and Hip Joints in Comparison to Conventional and Low-Dose Protocols.

To evaluate patients’ radiation exposure undergoing CT-guided joint injection in preparation of MR-arthrography. We developed a novel ultra-low-dose protocol utilizing tin-filtration, performed it in 60 patients and compared the radiation exposure (DLP) and success rate to conventional protocol (26 cases) and low-dose protocol (37 cases). We evaluated 123 patients’ radiation exposure undergoing CT-guided joint injection from 16 January–21 March. A total of 55 patients received CT-guided joint injections with various other examination protocols and were excluded from further investigation. In total, 56 patients received shoulder injection and 67 received hip injection with consecutive MR arthrography. The ultra-low-dose protocol was performed in 60 patients, the low-dose protocol in 37 patients and the conventional protocol in 26 patients. We compared the dose of the interventional scans for each protocol (DLP) and then evaluated success rate with MR-arthrography images as gold standard of intraarticular or extracapsular contrast injection. There were significant differences when comparing the DLP of the ultra-low-dose protocol (DLP 1.1 ± 0.39; p < 0.01) to the low dose protocol (DLP 5.3 ± 3.24; p < 0.01) as well as against the conventional protocol (DLP 22.9 ± 8.66; p < 0.01). The ultra-low-dose protocol exposed the patients to an average effective dose of 0.016 millisievert and resulted in a successful joint injection in all 60 patients. The low dose protocol as well as the conventional protocol were also successful in all patients. The presented ultra-low-dose CT-guided joint injection protocol for the preparation of MR-arthrography demonstrated to reduce patients’ radiation dose in a way that it was less than the equivalent of the natural radiation exposure in Germany over 3 days—and thereby, negligible to the patient.

MRA improves sensitivity than MRI for the articular-sided partial-thickness rotator cuff tears.

This study aims to compare the diagnostic accuracy of magnetic resonance imaging (MRI) and MR arthrography (MRA) for the articular-sided partial-thickness rotator cuff tear (PTRCT). Three electronic databases, PubMed/Medline, Embase and Cochrane Library, were utilized to retrieve articles comparing the diagnostic value of MRA and MRI for detecting articular-sided PTRCTs. The pooled statistical indexes included sensitivity, specificity, positive/negative predictive value, diagnostic odds ratio (DOR) and the area under the receiver operating characteristic curve (AUC). Eleven studies involving 1703 patients and 1704 shoulders were included. The pooled sensitivity, specificity, DOR and AUC and their 95% CIs of MRA to diagnose articular-sided PTRCTs were 0.81 (95% CI, 0.65-0.90), 0.96 (95% CI, 0.91-0.98), 68.14 (95% CI, 33.20-139.84) and 0.96 (95% CI, 0.94-0.97), respectively. The pooled sensitivity, specificity, DOR and AUC and their 95% CIs of MRI were 0.78 (95% CI, 0.65-0.87) and 0.97 (95% CI, 0.84-0.99), 47.82 (95% CI, 8.29-275.89) and 0.89 (95% CI, 0.86-0.92), respectively. This meta-analysis reveals that MRA has a better diagnostic value than that of MRI for the diagnosis of articular-sided partial-thickness rotator cuff tears because of an improvement of sensitivity.

Ultrasonography and MR Arthrogram in detection of shoulder joint disorders

Abstract Purpose To know the role of Ultrasonography and MR Arthrogram in detection of shoulder joint disorders Methods and material Thirty patients with suspected shoulder joint disorders underwent US,MRI ,MR arthrography shoulder. Results All cases with ALAPSA, Bankert, reverse bankert, hillsachs, perthes and SLAP are diagnosed accurately by MR arthrography with sensitivity of (100%) in GLAD ,Supraspinatus tendenopathy ,Supraspinatus tendon tear and IGHL injury sensitivity was decreased to 75%,in cases of paraglenid cysts arthrography did not diagnose any of them as there are no communication between the cyst and the joint Conclusion MR arthrography shoulder has a golden rule in diagnosis ,classification of cases of shoulder dislocation ,SLAP injuries and rotator cuff impingement

Defining the Gothic Arch Angle (GAA) as a radiographic diagnostic tool for instability in hip dysplasia

In recent years, there has been a controversial discussion about whether borderline dysplastic hips should be treated with an arthroscopic procedure or rather with an acetabular reorientation. New research suggests that a classification into stable and unstable hips may be helpful. The aim of the study was to validate (1) the intra- and interobserver reliability of a newly defined radiographic parameter named the Gothic Arch Angle, (2) the association between the GAA and previously existing measurements used to define severity of acetabular dysplasia, and (3) the correlation between radiographic measurements of acetabular dysplasia with MRI findings previously suggestive of hip instability. We defined and validated the GAA in 10 standardized radiographs of asymptomatic hips by two observers and calculated intra- and interobserver coefficients at two individual dates. Subsequently, a consecutive series of 100 patients with dysplastic hips (LCEA < 25°, Toennis grade ≤ 1) were evaluated for signs of instability on anteroposterior (a.p.) pelvic radiographs and direct MR arthrography and were divided in two groups: stable and unstable. In these patients the LCEA, the AI, the FEAR index and the GAA were radiographically evaluated. Correlation analyses and a logistic regression analysis was performed to identify the predictive value of instability for each radiographic parameter. Cutoff probabilities analysis was performed using standard receiver operating characteristic (ROC) curves to rate the predictive efficiency value of the GAA. The GAA showed excellent inter- and intraobserver reliability. A correlation was found between GAA and FEAR index. A logistic regression analysis showed that LCEA, FEAR index and GAA are distinct predictors of instability in hip dysplasia. The GAA showed the largest area under the curve (AUC 0.96), indicating it to be the best predictor of instability with an optimal cutoff value of 90° (sensitivity, 0.95; specificity, 0.93). The GAA is a new available indicator for instability and is thus suggested to be used as a future radiographic parameter for the stability of dysplastic hips. Further studies are needed to understand how this parameter might additionally predict clinical outcome in the treatment of hip dysplasia.Level of evidence: Level III, diagnostic study.