SSR white paper: guidelines for utilization and performance of direct MR arthrography.

OBJECTIVE: Direct magnetic resonance arthrography (dMRA) is often considered the most accurate imaging modality for the evaluation of intra-articular structures, but utilization and performance vary widely without consensus. The purpose of this white paper is to develop consensus recommendations on behalf of the Society of Skeletal Radiology (SSR) based on published literature and expert opinion. MATERIALS AND METHODS: The Standards and Guidelines Committee of the SSR identified guidelines for utilization and performance of dMRA as an important topic for study and invited all SSR members with expertise and interest to volunteer for the white paper panel. This panel was tasked with determining an outline, reviewing the relevant literature, preparing a written document summarizing the issues and controversies, and providing recommendations. RESULTS: Twelve SSR members with expertise in dMRA formed the ad hoc white paper authorship committee. The published literature on dMRA was reviewed and summarized, focusing on clinical indications, technical considerations, safety, imaging protocols, complications, controversies, and gaps in knowledge. Recommendations for the utilization and performance of dMRA in the shoulder, elbow, wrist, hip, knee, and ankle/foot regions were developed in group consensus. CONCLUSION: Although direct MR arthrography has been previously used for a wide variety of clinical indications, the authorship panel recommends more selective application of this minimally invasive procedure. At present, direct MR arthrography remains an important procedure in the armamentarium of the musculoskeletal radiologist and is especially valuable when conventional MRI is indeterminant or results are discrepant with clinical evaluation.

Increased signal of the fibular collateral ligament of the knee on MRI, clinically significant?

INTRODUCTION: The purpose of this study was to determine the clinical significance of signal hyperintensity in the proximal fibular collateral ligament (FCL) on coronal proton density (PD) fat-saturated (FS) MRI of the knee, a common finding. This study is unique in that it characterizes the FCL of a comprehensive, large cohort of both symptomatic and asymptomatic patients, which to our knowledge represents the first study with such broad inclusion criteria. METHODS: A large case series was performed analyzing MRI of the knee of 250 patients from July 2021 through September 2021 and retrospectively reviewed. All studies were performed on 3-Tesla MRI scanners with a dedicated knee coil and in accordance with standard institutional knee MRI protocol. Signal in the proximal fibular collateral ligament was assessed on coronal PDFS and axial T2-weighted FS images. Increased signal was classified as none, mild, moderate, or severe. A corresponding chart review of clinic notes was performed to determine the presence or absence of lateral knee pain. An FCL sprain or injury was considered present if the medical record described tenderness on palpation of the lateral knee, positive finding against resistance to the leg (varus stress test) or reverse pivot shift, or any clinical suspicion for lateral complex sprain or posterolateral corner injury. RESULTS: The majority (74%) of knee MRIs demonstrated the presence of increased signal in the proximal fibular collateral ligament on coronal PD FS images. <5% of these patients had associated clinical findings of fibular collateral ligament and/or lateral supporting structure injury. DISCUSSION: Although increased signal in the proximal FCL of the knee is a common finding on coronal PDFS images, the majority are not associated with clinical symptoms. Thus, this increased signal is likely not a pathological finding in the absence of clinical findings of fibular collateral ligament sprain/injury. Our study emphasizes the importance of clinical correlation in identifying increased signal in the proximal FCL as pathologic.

The Posterior Transtriceps Approach for Intra-articular Elbow Arthrography: A Painless Method?

We determined the diagnostic and patient experience advantage of the transtriceps approach for elbow arthrograms. MRIs of two patients who underwent an MRI arthrogram of the elbow in May and June 2022 were retrospectively evaluated. All procedures were performed under fluoroscopic guidance with the patient in the prone position and the arm of interest extended above the head, and the elbow of interest flexed at 90 degrees. A 25 gauge needle was utilized. All MRI examinations were performed on 3-Tesla MRI scanners (Siemens, Hamburg, Germany) and in accordance with our institution's standard elbow arthrogram MRI protocol. The arthrogram was deemed successful if contrast was visualized in the elbow joint, and the MRI examinations were assessed for diagnostic ability and extra-articular leakage. Patient comfort and pain were also assessed. Both arthrograms demonstrated adequate contrast in the elbow joint, and the MRIs confirmed no leakage of contrast or bubbles. The patients felt 0 pain during the procedure on a scale of 0-10. Although the radiocapitellar approach is commonly used for elbow arthrograms, we found the transtriceps approach to be diagnostically sound, painless, and easier to perform.

Lucent Patellar Lesions: A Pictorial Review.

A radiographically lucent patellar lesion may represent a variety of etiologies, ranging from more commonly seen degenerative, metabolic, infectious, developmental, posttraumatic, postoperative causes to rarer benign and malignant neoplasms. Clinical symptoms, surgical history, laboratory values, and radiographic features may help narrow the differential. In addition, radiographic features such as circumscribed borders and sharply delineated margins favor benign lesions while ill-defined margins suggest malignant etiologies. This case series illustrates the imaging findings and explores relevant clinical findings in a variety of interesting lucent patellar lesions.

The Reliability of 3-T Magnetic Resonance Imaging to Identify Arthroscopic Features of Meniscal Tears and Its Utility to Predict Meniscal Tear Reparability.

BACKGROUND: The ability to predict meniscus tear reparability based on preoperative magnetic resonance imaging (MRI) is desirable for postoperative planning; however, the accuracy of predictive methods varies widely within the orthopaedic and radiology literature. PURPOSE/HYPOTHESIS: The purpose was to determine if the higher resolution offered by 3-T MRI improves the accuracy of predicting reparability compared with previous investigations using 1.5-T MRI. Our hypothesis was that a higher field strength of 3-T MRI would result in improved reliability assessments and predictions of meniscus tear reparability compared with previous studies utilizing a 1.5-T MRI platform. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A total of 44 patients who underwent meniscus repair were matched by age, sex, and body mass index to 43 patients who underwent partial meniscectomy. Overall, 2 orthopaedic surgeons and 2 musculoskeletal radiologists independently and blindly reviewed the preoperative MRI scans for all 87 patients. For each meniscus tear, reviewers evaluated the following criteria: tear pattern, tear length, tear distance from the meniscocapsular junction, tear thickness, and integrity of any inner meniscal fragment. The resultant data were then applied to 5 different approaches for predicting meniscal reparability. RESULTS: The accuracy for all examined prediction methods was poor, ranging from 55% (3-point method) to 72% (classification tree method) among all reviewers. Interobserver reliability for examined criteria was also poor, with kappa values ranging from 0.07 (inner meniscal fragment status) to 0.40 (tear pattern). CONCLUSION: MRI continues to be a poor predictor of meniscus tear reparability as assessed by arthroscopic criteria, even when using higher resolution 3-T scanners. Interobserver reliability in this setting can be poor, even among experienced clinicians.

Aggressive osteoblastoma with a secondary aneurysmal bone cyst treated with denosumab.

Osteoblastomas and aneurysmal bone cysts (ABC) are rare benign bone tumors that make up about 1%-2% of primary bone malignancies, typically occurring in young patients with a median age of 20 years, most commonly effecting the axial skeleton. ABCs may develop independently as primary lesions, or secondary to other bony lesions including osteoblastomas, chondroblastomas, and giant cell tumors. Treatment of unresectable or extensive osteoblastomas can be challenging. In 2013, the Food and Drug Administration (FDA) approved denosumab for the treatment of giant cell tumors of the bone due to its efficacy in these morbid bony lesions. Various case reports have shown that osteoblastomas can respond to denosumab. Furthermore, numerous ABC case reports have described the efficacy of denosumab in these situations. We herein describe a unique case of a young patient with an aggressive osteoblastoma and secondary ABCs who was successfully treated with denosumab.

VIDEO: Dynamic Ultrasound for Snapping Hip Syndrome.

OBJECTIVE. The purpose of this video article is to review the dynamic sonographic assessment of snapping hip syndrome. The video focuses on the extraarticular forms of snapping hip and discusses their possible causes, ultrasound features, and treatment options. The dynamic sonographic technique for evaluating snapping hip syndrome is shown with live scanning videos. CONCLUSION. Dynamic ultrasound is well suited for the assessment of snapping hip syndrome and is essential for confirming the clinical diagnosis of the condition.

ACR Appropriateness Criteria® Primary Bone Tumors.

Although primary bone tumors are relatively uncommon, appropriate imaging evaluation is essential when they are suspected or incidentally detected. In almost all cases, radiographs are the most appropriate initial imaging study for screening and characterization of primary bone tumors. Radiographs often provide sufficient information for diagnosis and to guide the treating clinician. However, when conventional radiographs alone are inadequate, they still often guide the selection of the most appropriate next step for advanced imaging. MRI and CT are typically the most appropriate next step. MRI provides excellent soft-tissue contrast allowing for evaluation of the tissue composition (such as fat, hemorrhage, fluid levels) and anatomic extent of bone tumors. CT provides complementary information, with its ability to detect subtle matrix mineralization or periosteal reaction that may not be seen on radiographs or MRI. This publication focuses on six common variants to guide diagnosis and management of primary bone tumors. In addition to conventional radiographs, appropriate use of MRI, CT, PET/CT, bone scan, and ultrasound are discussed. 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.

ACR Appropriateness Criteria® Suspected Osteomyelitis of the Foot in Patients With Diabetes Mellitus.

Diabetes-related foot complications such as soft-tissue infection, osteomyelitis, and neuropathic osteoarthropathy account for up to 20% of all diabetic-related North American hospital admissions. Radiography of the foot is usually appropriate as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. For follow-up examination, MRI of the foot with or without contrast enhancement demonstrates excellent soft-tissue contrast and sensitivity to marrow abnormalities with high-resolution detail in multiple anatomic planes and is usually appropriate when osteomyelitis or early neuropathic arthropathy is suspected. This publication of diabetes-related foot complications summarizes the literature and makes recommendations for imaging based on the available data. 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.

Oncologic Accuracy of Image-guided Percutaneous Core-Needle Biopsy of Peripheral Nerve Sheath Tumors at a High-volume Sarcoma Center.

OBJECTIVES: Peripheral nerve sheath tumors (PNSTs) are clinically heterogenous, comprising benign (BPNST) and malignant (MPNST) variants. BPNSTs can be managed with nerve-sparing excision or observation. MPNSTs require radical resection and multidisciplinary oncologic management (1, 15). Image-guided core-needle biopsy (IGCNBx) is the well-established standard to obtain preoperative tissue diagnosis of soft tissue tumors. However, there has been resistance to performing IGCNBx of PNSTs because of the presumed risk of nerve injury and unknown accuracy in determining malignancy. We sought to define the accuracy and safety of IGCNBx in PNSTs. MATERIALS AND METHODS: All patients that underwent both IGCNBx and surgical resection of a PNST at our institution between 2002 and 2016 were analyzed. The accuracy of IGCNBx in determining malignancy was calculated, including subgroup analyses by histologic subtype and neurofibromatosis 1 status. Complication data were collected and analyzed. RESULTS: Among the 78 PNSTs with IGCNBx and postresection surgical pathology, 76% (n=59) had BPNST and 24% (n=19) had MPNST on postresection surgical pathology. IGCNBx accurately determined malignancy in 94% of cases. IGCNBx demonstrating schwannoma or MPNST were 100% accurate in determining malignancy. IGCNBx demonstrating neurofibroma or indeterminate results were 33% and 57% malignant on postresection surgical pathology, respectively. There were no long-term complications, including sensory or motor deficits, from IGCNBx. CONCLUSIONS: Percutaneous IGCNBx demonstrates 94% accuracy in differentiating benign from malignant PNSTs. IGCNBx demonstrating neurofibroma or indeterminate pathology should be interpreted with caution because of risk of malignant reclassification on surgical pathology. Our results reaffirm the safety of IGCNBx, as no patients experienced long-term complications.

ACR Appropriateness Criteria® Suspected Spine Trauma.

Injuries to the cervical and thoracolumbar spine are commonly encountered in trauma patients presenting for treatment. Cervical spine injuries occur in 3% to 4% and thoracolumbar fractures in 4% to 7% of blunt trauma patients presenting to the emergency department. Clear, validated criteria exist for screening the cervical spine in blunt trauma. Screening criteria for cervical vascular injury and thoracolumbar spine injury have less validation and widespread acceptance compared with cervical spine screening. No validated criteria exist for screening of neurologic injuries in the setting of spine trauma. CT is preferred to radiographs for initial assessment of spine trauma. CT angiography and MR angiography are both acceptable in assessment for cervical vascular injury. MRI is preferred to CT myelography for assessing neurologic injury in the setting of spine trauma. MRI is usually appropriate when there is concern for ligament injury or in screening obtunded patients for cervical spine instability. 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.

ACR Appropriateness Criteria® Acute Hand and Wrist Trauma.

Hand and wrist injuries are common reasons for musculoskeletal-related emergency department visits. Imaging is essential for evaluating many of these injuries. In most cases, conventional radiographs provide sufficient information to guide the treating clinician. This review focuses on seven common variants to guide diagnosis of hand and wrist injuries. In addition to radiographs, appropriate use of CT, MRI, bone scan, and ultrasound are discussed. 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.

Increased signal in the proximal patellar tendon: normal or pathologic?

OBJECTIVE: To determine the clinical significance of T2 signal hyperintensity in the proximal patellar tendon seen on MRI of the knee. MATERIALS AND METHODS: MRIs of 100 patients who underwent MRI of the knee between 1 May 2018 and 15 July 2018 were retrospectively evaluated. All examinations were performed on 3-Tesla MRI scanners with a dedicated knee coil and in accordance with our institution's standard knee MRI protocol. The presence of increased T2 signal was assessed on both sagittal and axial T2-weighted fat-saturated images. The amount of increased signal in the proximal patellar tendon on T2-weighted images was characterized as: none, mild, moderate, or severe. A corresponding chart review of the referring physicians' notes was performed to determine the presence of clinical symptoms of patellar tendinopathy. Patellar tendinopathy was considered present if the clinical notes described tenderness on palpation of the inferior patellar pole, infrapatellar tenderness, or patellar tendinosis/tendinitis. RESULTS: The majority (66%) of knee MRIs demonstrated the presence of increased T2 signal in the proximal patellar tendon. Only 4.5% of these patients had associated clinical findings of patellar tendinopathy. CONCLUSION: Although increased T2 signal in the proximal patellar tendon is a common finding, only in rare cases are there associated clinical symptoms. Thus, increased T2 signal in the proximal patellar tendon may not be a pathological finding in the absence of clinical findings of patellar tendinopathy.

Efficacy of intraarticular corticosteroid hip injections for osteoarthritis and subsequent surgery.

OBJECTIVE: Our study aimed to determine the duration of pain relief from intraarticular hip corticosteroid injections and identify patient predictive factors on injection response. We also sought to determine the subsequent rate of hip surgery and whether severity of hip osteoarthritis or injection response correlated with the decision to undergo surgery. MATERIALS AND METHODS: All intraarticular hip steroid injections performed for osteoarthritis under fluoroscopic guidance at a single institution between January 2010 to December 2012 were retrospectively reviewed. Response was divided into three groups: no relief, immediate (≤ 2 weeks of pain relief), and continued (> 2 weeks of pain relief). Presence of hip surgery for osteoarthritis performed within 2 years following injection was obtained. Correlation between patient characteristics with injection outcome and hip surgery was analyzed. RESULTS: Of 78 patients, a total of 82 injections were analyzed. For injections, 19.5% (16/82) showed no response, 47.6% (39/82) showed immediate response, and 32.9% (27/82) showed continued response. There was no significant correlation between injection outcome with age, Tönnis grade, BMI, or duration of symptoms. In total, 48.7% had hip surgery within 2 years after initial injection. There was a significant association between Tönnis grade and surgery, with higher Tönnis grades correlating with decision to undergo surgery (p = 0.002). CONCLUSIONS: Gender, age, BMI, duration of symptoms, and radiographic severity of disease do not predict injection response. Due to high surgical rates and poor response, intraarticular hip steroid injections may be less effective in the long term, and surgical management may be considered earlier.

ACR Appropriateness Criteria® Soft-Tissue Masses.

Imaging is an integral component of the evaluation of patients with a suspected soft-tissue mass. Imaging can not only confirm the presence of a mass but can provide essential information necessary for diagnosis, local staging, and biopsy planning. Although the objectives of the evaluation have not changed, the choices available for imaging of musculoskeletal masses have evolved dramatically in recent years. The purpose of this document is to identify the most common clinical scenarios and the most appropriate imaging for their assessment on the basis of the current literature and to provide general guidance for those scenarios that are not specifically addressed. 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.

ACR Appropriateness Criteria® Shoulder Pain-Traumatic.

Traumatic shoulder pain is pain directly attributed to a traumatic event, either acute or chronic. This pain may be the result of either fracture (the clavicle, scapula, or proximal humerus) or soft-tissue injury (most commonly of the rotator cuff, acromioclavicular ligaments, or labroligamentous complex). Imaging assessment of traumatic shoulder pain begins with conventional radiography and, depending on physical examination findings, will require MRI or MR arthrography for assessment of soft-tissue injuries and CT for delineation of fracture planes. Ultrasound excels in assessment of rotator cuff injuries but has limited usefulness for assessment of the deep soft-tissues. CT angiography and conventional arteriography are helpful for assessment of vascular injury, and bone scintigraphy can be used in assessment of complex regional pain syndrome after traumatic shoulder injury. 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.

Is Core Needle Biopsy Reliable in Differentiating Between Aggressive Benign and Malignant Radiolucent Bone Tumors?

BACKGROUND: Although there is widespread acceptance of core needle biopsy (CNB) for diagnosing solid tumors, there is reluctance by some clinicians to use CNB for aneurysmal bone cysts (ABCs) as a result of concerns of safety (bleeding, nerve injury, fracture, readmission, or infection) and reliability, particularly to rule out malignant diagnoses like telangiectatic osteosarcoma. This is especially true when CNB tissue is sent from an outside hospital, where the technique used to obtain the tissue may be spurious. QUESTIONS/PURPOSES: (1) Is CNB effective (provided adequate information to indicate appropriate surgical treatment without further open biopsy) as an initial diagnostic test for ABC? (2) Is CNB accurate (pathology consistent with the subsequent definitive surgical pathologic diagnosis) in differentiating between benign lesions such as primary or secondary ABCs and malignant radiolucent lesions such as telangiectatic osteosarcoma? (3) What are the complications of CNB? (4) Is there any difference in the effectiveness or accuracy of CNB performed at outside institutions when compared with a referral center? METHODS: A retrospective study of our musculoskeletal tumor board pathology database (1990-2016) was performed using search criteria "aneurysmal bone cyst" or "telangiectatic osteosarcoma." Only patients undergoing a CNB who proceeded to definitive surgical resection with final pathology were included. Excluding outside CNBs, CNB was performed after presentation at a musculoskeletal tumor board as a result of atypical features on imaging or history concerning for malignancy. Outside CNB tissue was reviewed by our pathologists. If there was sufficient tissue for diagnosis, the patient proceeded to definitive surgery. If not, the patient underwent open biopsy. CNB diagnosis, open biopsy results, and open surgical resection pathology were reviewed. Complications, including bleeding, infection, nerve injury, readmission, or fracture, between the CNB and definitive open surgical procedure (mean 1.6 months) were documented. CNBs were considered "effective" if they yielded pathology considered sufficient to proceed with appropriate definitive surgery without additional open biopsy. CNBs were considered "accurate" if they were effective and yielded a pathologic diagnosis that matched the subsequent definitive surgical pathology. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of obtaining a malignant diagnosis using CNB were also calculated. RESULTS: A total of 81% (59 of 73) of CNBs were effective. Ninety-three percent (55 of 59) of CNBs were classified as accurate. Diagnostic CNBs had a sensitivity and specificity of 89% (eight of nine) and 100% (51 of 51), respectively. The PPV was 1.00 and the NPV was 0.82. There were no complications. With the numbers available, there was no difference in efficacy (90% [37 of 41 versus 14 of 15]; odds ratio, 0.97 [95% confidence interval {CI}, 0.41-2.27], p = 0.94) or accuracy (92% [34 of 37 versus 13 of 14]; odds ratio, 0.87 [95% CI, 0.08-9.16], p = 0.91) between CNBs performed in house and those referred from outside. CONCLUSIONS: These data suggest that CNBs are useful as an initial diagnostic test for ABC and telangiectatic osteosarcoma. Tissue from outside CNBs can be read reliably without repeat biopsy. If confirmed by other institutions, CNB may be considered a reasonable approach to the diagnosis of aggressive, radiolucent lesions of bone. LEVEL OF EVIDENCE: Level III, diagnostic study.

Intraneural Hemangioma: Case Report of a Rare Tibial Nerve Lesion.

An intraneural hemangioma is a rare, benign mesodermal lesion. We present a case of a three-year-old female with the inability to straighten her right knee and fullness over the right popliteal fossa for one year. Magnetic resonance imaging (MRI) demonstrated a T2 hyperintense lesion of the popliteal fossa, within the tibial nerve. The patient underwent an uncomplicated right knee excisional biopsy, which confirmed the diagnosis of an intraneural hemangioma. Although rare, an intraneural hemangioma should be considered in the differential diagnosis of a soft tissue lesion located in the expected course of a peripheral nerve.

Relationship of ACL Injury and Posterior Tibial Slope With Patient Age, Sex, and Race.

BACKGROUND: Posterior tibial slope (PTS) has been proposed as a potential risk factor for anterior cruciate ligament (ACL) injury; however, studies that have examined this relationship have provided inconclusive and sometimes contradictory results. Further characterization of this relationship may enable the medical community to identify individuals at greater risk for ACL injury and possibly characterize an anatomic target during surgical reconstruction. PURPOSE: The primary goal was to investigate the relationship between PTS and ACL injury. The secondary goal was to determine whether there are any patient factors, such as age, race, or sex, that correlate with ACL injury and PTS. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Medical records of 221 patients who underwent magnetic resonance imaging (MRI) of the knee between January 2003 and December 2009 were reviewed. Patients were separated into 2 groups: a study group of those subjects who had undergone surgery for ACL injury (n = 107) and a control group of patients diagnosed with patellofemoral syndrome (n = 114). Demographic data were collected, and MRI images from both groups were analyzed using imaging software to obtain medial and lateral tibial slope measurements. Data were then analyzed using analysis of variance (ANOVA) comparison and a multivariable regression model to determine which, if any, patient factors were related to probability of having an ACL injury. RESULTS: ANOVA comparison demonstrated that the study group had significantly greater values for lateral PTS (6° ± 4°; P < .001) and medial PTS (7° ± 4°; P = .002) compared with controls (5° ± 3° and 5° ± 4°, respectively). After stepwise elimination of nonsignificant variables, the final multivariable logistic regression model determined that age (odds ratio [OR], 0.94; P < .001) and lateral PTS (OR, 1.12; P = .002) had statistically significant relationships with ACL injury. Medial PTS, race, and sex were not demonstrated to be significant predictors of ACL injury in this final model. CONCLUSION: This study demonstrates a relationship between increased lateral PTS and ACL injury, which corroborates the findings of previously published studies. The findings presented in this article may help identify patients who are at greater risk of ACL injury and could potentially benefit from treatments aimed at modification of PTS.