Faculty Bibliography

BACKGROUND/UNASSIGNED:Patients with symptomatic femoroacetabular impingement (FAI) typically have anterior groin pain. However, a subset of these patients may have pain located laterally, posteriorly, or in a combination of locations around the hip. PURPOSE/UNASSIGNED:To report and compare outcomes of hip arthroscopy for patients with FAI and atypical hip pain versus classic anterior groin pain. STUDY DESIGN/UNASSIGNED:Cohort study; Level of evidence, 2. METHODS/UNASSIGNED:Consecutive patients undergoing hip arthroscopy for FAI between August 2011 and March 2013 were identified. A total of 258 patients were identified as having symptomatic FAI based on clinical, radiographic, and advanced imaging diagnosis of FAI. Exclusion criteria included isolated thigh, knee, or low back pain. We also excluded patients with hip abductor pathology and trochanteric bursitis. Of the 226 patients ultimately included, 159 (70.4%) reported anterior groin pain, while 67 (29.6%) reported isolated lateral or posterior hip pain or a combination of locations. Patients were categorized into 4 groups: isolated anterior groin pain, lateral hip pain, posterior hip pain, and multiple primary hip pain locations (combined). These patients were followed prospectively with a minimum follow-up of 2 years. Patient characteristics, surgical characteristics, modified Harris Hip Score (mHHS), Non-arthritic Hip Score (NAHS), revision hip arthroscopy, and conversions to total hip arthroplasty (THA) were recorded. RESULTS/UNASSIGNED:All 226 patients were included at final follow-up. Hip arthroscopy was performed by a single sports medicine fellowship-trained orthopaedic surgeon. Preoperative patient characteristics and baseline functional outcome scores did not significantly differ among groups. All 4 groups showed statistically significant improvements in mHHS and NAHS from baseline to final follow-up of a mean 2.63 years (range, 2.01-3.23 years). Functional outcome scores and rates of revision hip arthroscopy or conversion to THA did not significantly differ between groups. CONCLUSION/UNASSIGNED:Hip arthroscopy can effectively improve patient outcomes in atypical hip pain. A careful history and physical examination should identify this clinically meaningful subset of patients with FAI who can benefit from surgical intervention while identifying patients with concomitant posterior extra-articular hip or spine pathology that should be addressed appropriately.

Background The MRI manifestations of subspine impingement (SSI) other than morphologic features of anterior inferior iliac spine (AIIS) have not been extensively explored and validated. Purpose To determine the MRI findings associated with SSI, including AIIS morphologic features, femoral distal cam, and associated soft-tissue injuries. Materials and Methods This is a retrospective study of symptomatic patients who underwent arthroscopic treatment for femoroacetabular impingement between December 2014 and March 2017, with preoperative MRI within 6 months before surgery. The SSI group included patients with clinical and intraoperative findings of SSI; the remaining patients comprised the non-SSI group. Preoperative MRI findings were independently assessed by two radiologists who were blinded to clinical information. Interreader agreement was assessed, and multivariable logistic regression was also used. Results A total of 62 patients (mean age ± standard deviation, 42.1 years ± 11.9; 38 women) were included. SSI was diagnosed in 20 of the 62 patients (32%) (mean age, 43 years ± 12); 42 patients (68%) did not have SSI (mean age, 41 years ± 10). Reader 1 detected distal cam in 16 of the 20 patients with SSI (80%) and eight of the 42 patients without SSI (19%), and reader 2 detected distal cam in 15 of the 20 patients with SSI (75%) and eight of the 42 patients without SSI (19%) (P < .001 for both). Reader 1 detected signs of impingement on the distal femoral neck (IDFN) in 18 of the 20 patients with SSI (90%) and seven of the 42 patients without SSI (16%), and reader 2 detected signs of IDFN in 13 of the 20 patients with SSI (65%) and nine of the 42 patients without SSI (21%) (P < .001 and P = .001, respectively). Reader 1 detected superior capsular edema in 15 of 20 patients with SSI (75%) and three of 42 patients without SSI (7%), and reader 2 detected superior capsular edema in 17 of 20 patients with SSI (85%) and 22 of 42 patients without SSI (52%) (P < .001 and P = .02, respectively). Distal cam was a predictor of SSI after adjustment for IDFN. Interreader agreement was substantial for distal cam (κ = 0.80) and moderate for IDFN (κ = 0.50). Conclusion Soft-tissue injuries and osseous findings other than morphologic features of the anterior inferior iliac spine were associated with subspine impingement. © RSNA, 2019 See also the editorial by Guermazi in this issue.

OBJECTIVE:The outcome of arthroscopic treatment for femoroacetabular impingement (FAI) depends on the preoperative status of the hip cartilage. Quantitative T2 can detect early biochemical cartilage changes, but its routine implementation is challenging. Furthermore, intrinsic T2 variability between patients makes it difficult to define a threshold to identify cartilage lesions. To address this, we propose a normalized T2-index as a new method to evaluate cartilage in FAI. DESIGN/METHODS:We retrospectively analyzed magnetic resonance imaging (MRI) data of 18 FAI patients with arthroscopically confirmed cartilage defects. Cartilage T2 maps were reconstructed from multi-spin-echo 3-T data using the echo-modulation-curve (EMC) model-based technique. The central femoral cartilage, assumed healthy in early-stage FAI, was used as the normalization reference to define a T2-index. We investigated the ability of the T2-index to detect surgically confirmed cartilage lesions. RESULTS:The average T2-index was 1.14 ± 0.1 and 1.13 ± 0.1 for 2 separated segmentations. Using T2-index >1 as the threshold for damaged cartilage, accuracy was 88% and 100% for the 2 segmentations. We found moderate intraobserver repeatability, although separate segmentations yielded comparable accuracy. Damaged cartilage could not be identified using nonnormalized average T2 values. CONCLUSIONS:This preliminary study confirms the importance of normalizing T2 values to account for interpatient variability and suggests that the T2-index is a promising biomarker for the detection of cartilage lesions in FAI. Future work is needed to confirm that combining T2-index with morphologic MRI and other quantitative biomarkers could improve cartilage assessment in FAI.

PURPOSE/OBJECTIVE:To compare femoroacetabular motion in a series of consecutive symptomatic patients with hip pain throughout the range of motion of the hip using a real-time radial gradient echo (GRE) sequence in addition to the routine hip protocol sequences for magnetic resonance (MR) arthrographic assessment of patients with and without clinical femoroacetabular impingement (FAI) syndrome. In particular, we sought to assess whether the additional dynamic sequence could differentiate between patients with and without a positive physical exam maneuver for FAI syndrome. METHODS:Patients with hip pain referred for conventional hip MR arthrogram including those with and without a positive physical exam maneuver for FAI syndrome were imaged using routine hip MR arthrogram protocol and an additional real-time radial 2-dimensional GRE acquisition at 3 Tesla in an axial oblique plane with continuous scanning of a 9 mm thick slice through the center of the femoral head-neck axis. Patients who were unable to move through the range of motion were excluded (n = 3). Patients with acetabular dysplasia (defined by a lateral center-edge angle [CEA] of 20°) were also excluded, as were patients had Kellgren and Lawrence scores of > 0. The real-time cine sequence was acquired with the patient actively moving through neutral, flexion, flexion-abduction external-rotation, and flexion-adduction internal rotation (FADIR) positions aiming for 40° of abduction, then 25° of adduction at 80° to 90° flexion. Due to the placement of the coil over the hip, a true FADIR was precluded. Images were evaluated independently by 2 musculoskeletal radiologists measuring the joint space in the anterior, central, and posterior positions at each point during range of motion for femoroacetabular cortical space (FACS). Anterior FACS narrowing was calculated as the ratio of joint space in FADIR:neutral position, with lower ratios indicating greater narrowing. Static metrics including alpha angle, CEA, grade of cartilage loss according the Outerbridge classification, and patient demographics were also recorded. RESULTS:Twenty-two painful hips in 22 patients (11 males and 11 females) with mean age 36 years (range, 15-67) were included. Twelve patients had a positive physical exam maneuver for FAI syndrome. The time to perform the dynamic sequence was 3 to 6 minutes. Interobserver agreement was strong, with intraclass correlation 0.91 and concordance correlation 0.90. According to results from both readers, patients with impingement on clinical exam had significantly lower anterior FACS ratios compared with those without clinical impingement (reader 1: 0.39 ± 0.10 vs 0.69 ± 0.20, P = .001; reader 2: 0.36 ± 0.07 vs 0.70 ± 0.17, P < .001). Decreased anterior FACS ratio was found to be significantly correlated to increased alpha angle by both readers (reader 1: R = -0.63, P = .002; reader 2: R = -0.67, P = .001) but not significantly correlated to CEA (reader 1: R = 0.13, P = .561; reader 2: R = 0.20, P = .378) or cartilage loss (reader 1: R = 0.03, P = .885; reader 2: R = -0.06, P = .784). Both readers found patients with an anterior FACS ratio of 1/2 to have significantly higher mean alpha angle (reader 1: 62.88 vs 52.79, P = .038; reader 2: 63.50 vs 50.58, P = .006); however, there were no significant differences in cartilage loss (reader 1: P = .133; reader 2: P = .882) or CEA (reader 1: P = .340; reader 2: P = .307). CONCLUSIONS:A dynamic radial 2-dimensional-GRE sequence can be added to standard hip MR arthrogram protocols in <6 minutes, allowing assessment of dynamic femoroacetabular motion with strong interreader agreement. Patients with impingement on clinical exam had significantly lower anterior FACS ratios between FADIR and neutral positions, compared with those without clinical impingement. LEVEL OF EVIDENCE/METHODS:Level III, comparative diagnostic investigation.

Objectives: Bone Marrow Lesions (BML) are a common finding on knee MRI. In the knee, BML have a strong correlation to patient-reported pain, function, joint deterioration and rapid progression to TKR. Histologic analyses of BML have demonstrated findings consistent with fracture and bony remodeling of the trabeculae. The Subchondroplasty (SCP) Procedure aims to treat the bone defects present in the BML by percutaneously filling them with a bone substitute material, designed to flow through intact bone, harden at body temperature and then heal through natural bone turnover. Previous retrospective, single-center case series have demonstrated improvements in patient-reported outcomes. The purpose of this prospective, multi-center study is to evaluate the 2- year clinical and radiographic outcomes of patients with BML of the knee treated with the Subchondroplasty Procedure.
Method(s): Seventy patients were treated between 2012 and 2017 for BML of the tibial plateau and/or femoral condyle. Self-drilling cannulas were inserted into the BML using arthroscopic and fluoroscopic guidance, then injected with AccuFill Bone Substitute Material. All patients also underwent arthroscopy to aid in targeting the underlying bony lesion and address intra-articular pathology. MRIs and radiographs were obtained pre-operatively, at 6, 12 and 24 months, with additional radiographs collected at 6 weeks and 3 months. Patient-reported outcomes, including VAS pain, IKDC and KOOS were collected pre-operatively, 2 and 6 weeks, and 3, 6, 12 and 24 months post-operatively.
Result(s): Seventy patients (36 males and 34 females), average age 57 were consented and enrolled in the study. Preoperative K-L grade included 1.4% Grade 0, 2.9% Grade 1, 27.1% Grade 2, 55.7% Grade 3 and 7.1% Grade 4. Fifty eight tibial plateaus and 41 femoral condyles were treated (29 bipolar lesions treated). VAS Pain scores improved from a mean of 6.2/10 pre-op to 2.9/10 at 1 year. IKDC scores improved from mean 33.9 pre-op to 61.3 at 1 year. KOOS scores improved from baseline to 1 year (Fig. 1) with mean KOOS Pain from 45.8 to 73.9, ADL 52.9 to 79.2, Symptoms 49.7 to 71.9, Sports 21.2 to 49.9 and Quality of Life 18.1 to 52.3. All patient-reported outcomes showed statistically significant improvement at one year. Two year outcomes collected to date appear to follow the same trend. The last study subject is due to return in January 2019 at which point the final 2 year analysis will be completed. Six patients (8.6%) converted to arthroplasty (1 UKA and 5 TKA) at one year. To date, the 24 month conversion rate is 16.1% out of 62 subjects. The final conversion rate for 24 months will be calculated after the final subject returns. Radiographs and MRIs demonstrated good incorporation of the AccuFill material through 12 months with evidence of early remodeling and a lack of OA progression in the majority of subjects. Twenty-four month MRIs demonstrate continued remodeling of the AccuFill material.
Conclusion(s): This study presents statistically and clinically-meaningful evidence of improvements in clinical outcomes following Subchondroplasty procedure for BML of the knee. The low conversion rate suggests this lessinvasive procedure may delay the need for knee arthroplasty. MR imaging demonstrates good incorporation of the BSM and evidence of remodeling and reduction in material volume over time

OBJECTIVE:To determine if hip 3D-MR imaging can be used to accurately demonstrate femoral and acetabular morphology in the evaluation of patients with femoroacetabular impingement. MATERIALS AND METHODS/METHODS:We performed a retrospective review at our institution of 17 consecutive patients (19 hips) with suspected femoroacetabular impingement who had both 3D-CT and 3D-MRI performed of the same hip. Two fellowship-trained musculoskeletal radiologists reviewed the imaging for the presence and location of cam deformity, anterior-inferior iliac spine variant, lateral center-edge angle, and neck-shaft angle. Findings on 3D-CT were considered the reference standard. The amount of radiation that was spared following introduction of 3D-MRI was also assessed. RESULTS:All 17 patients suspected of FAI had evidence for cam deformity on 3D-CT. There was 100% agreement for diagnosis (19 out of 19) and location (19 out of 19) of cam deformity when comparing 3D-MRI with 3D-CT. There were 3 type I and 16 type II anterior-inferior iliac spine variants on 3D-CT imaging with 89.5% (17 out of 19) agreement for the anterior-inferior iliac spine characterization between 3D-MRI and 3D-CT. There was 64.7% agreement when comparing the neck-shaft angle (11 out of 17) and LCEA (11 out of 17) measurements. The use of 3D-MRI spared each patient an average radiation effective dose of 3.09 mSV for a total reduction of 479 mSV over a 4-year period. CONCLUSION/CONCLUSIONS:3D-MR imaging can be used to accurately diagnose and quantify the typical osseous pathological condition in femoroacetabular impingement and has the potential to eliminate the need for 3D-CT imaging and its associated radiation exposure, and the cost for this predominantly young group of patients.

Hip MRI and arthroscopy have important roles for the evaluation of the patient with hip pain. An understanding of what orthopedic surgeons want to know before and after hip arthroscopy as well as the limitations of arthroscopy would enable radiologists to improve their imaging interpretations and produce more clinically relevant, management guiding reports. The goal of this article is to review the basic principles of hip arthroscopy and MRI and compare their strengths and weaknesses. Normal clinically relevant hip anatomy, important pathologic conditions such as labral tears and cartilage injuries, femoroacetabular impingement specific findings like cam and pincer morphology, extra-articular conditions such as abductor and iliopsoas tendons pathology and common post-operative appearances are reviewed on MRI and arthroscopy.

Hip arthroscopy as we know it today developed over the last 15 to 20 years, yet its true beginning is far more dated. Initially developed as a means of removing loose bodies or as a means of lavage, hip arthroscopy was not utilized to treat femoroacetabular impingement (FAI) until much later. Its usefulness as a means of treating FAI did not arise until hip impingement was understood to be causal in the development of degenerative changes of the labrum and articular surfaces. As our understanding of FAI grew, the tools for treating it developed in tandem. Open treatment of FAI had been the first treatment of choice as this allowed for circumferential access to the femoral head, labrum, and acetabulum, which could be done without compromising femoral head perfusion. Yet, as arthroscopic techniques evolved, allowing for better access to the femoral head, labrum, and acetabulum, treatment of FAI with arthroscopy became the norm. However, several recent reports of revision hip arthroscopy for treatment of residual FAI have exposed potential shortcomings of arthroscopic treatment of FAI, specifically limitations with hip arthroscopy's ability to address large or complex cam and pincer deformities. While hip arthroscopy can certainly be useful for treatment of FAI in some patients, we have yet to identify which patients truly benefit from this minimally invasive approach and those who are better served by open surgical techniques. Honing our understanding of the pathology of FAI will help improve patient selection and therefore patient outcomes.

PURPOSE/OBJECTIVE:To use a large heterogeneous population to identify independent risk factors for revision surgery or conversion to total hip arthroplasty (THA) after hip arthroscopy. METHODS:The New York Statewide Planning and Research Cooperative System database was queried from 2011 through 2012 to identify patients undergoing hip arthroscopy. All patients aged 18 years or older who underwent hip arthroscopy according to Current Procedural Terminology coding were included. We chose to divide surgical volume into tertiles for the purposes of statistical analysis. Longitudinal analysis for a minimum of 2 years was performed to determine risk factors for revision surgery or conversion to THA. RESULTS:We identified 3,957 patients. The mean age was 35.8 years (standard deviation, 13.1 years). After a minimum follow-up period of 2 years, the overall failure rate was 9.6%: 3.7% of patients underwent revision hip arthroscopy at an average of 15.8 months, whereas 5.9% underwent conversion to THA at 14.7 months. Index surgery performed by surgeons in the third tertile of surgical volume (<40 cases per annum) was an independent risk factor for revision (odds ratio [OR], 1.71; P = .001), as well as conversion to THA (OR, 1.90; P < .001). Female patients (OR, 1.8; P < .001), older patients (OR, 3.4; P < .001), and patients with a history of obesity (OR, 5.6; P < .001) underwent conversion to THA at significantly higher rates than other patients. Young patients (OR, 4.4; P < .001) and female patients (OR, 1.6; P < .001) were more likely to undergo revision hip arthroscopy. CONCLUSIONS:Our analysis of 3,957 patients found that female sex, age under 40 years, absence of a labral repair, and index procedure performed by a low-volume surgeon were independent risk factors for revision hip arthroscopy. Age over 60 years, index procedure performed by a low-volume surgeon, female sex, obesity, and the presence of pre-existing arthritis were risk factors for THA conversion. LEVEL OF EVIDENCE/METHODS:Level III, case-control study.

Primary repair of acetabular labral tears has been the gold standard treatment with excellent short to mid-term results. Autograft and allograft labral reconstruction has been described mostly in the revision labral surgery setting with good short-term results. A recent study has compared primary labral reconstruction to labral repair head-to-head in the same patient. Primary labral reconstruction may be a suitable alternative to labral repair in patients with symptomatic labral pathology. Concerns remain, however, about sacrificing living labral tissue for dead allograft tissue for the long term.