3.0T magnetic resonance imaging-based hip bone models for femoroacetabular impingement syndrome are equivalent to computed tomography-based models.

This study aimed to compare three-dimensional (3D) proximal femoral and acetabular surface models generated from 3.0T magnetic resonance imaging (MRI) to the clinical gold standard of computed tomography (CT). Ten intact fresh-frozen cadaveric hips underwent CT and 3.0T MRI scans. The CT- and MRI-based segmented models were superimposed using a validated 3D-3D registration volume-merge method to compare them. The least surface-to-surface distance between the models was calculated by a point-to-surface calculation algorithm using a custom-written program. The variables of interest were the signed and absolute surface-to-surface distance between the paired bone models. One-sample t-tests were performed using a signed and absolute test value of 0.16 mm and 0.37 mm, respectively, based on a previous study that validated 1.5T MRI bone models by comparison with CT bone models. For the femur, the average signed and absolute surface-to-surface distance was 0.18 ± 0.09 mm and 0.30 ± 0.06 mm, respectively. There was no difference in the signed surface-to-surface distance and the 0.16 mm test value (t = 0.650, p = 0.532). However, the absolute surface-to-surface difference was less than the 0.37 mm test value (t = -4.025, p = 0.003). For the acetabulum, the average signed and absolute surface-to-surface distance was -0.06 ± 0.06 mm and 0.26 ± 0.04 mm, respectively. The signed (t = -12.569, p < 0.001) and absolute (t = -8.688, p < 0.001) surface-to-surface difference were less than the 0.16 mm and 0.37 mm test values, respectively. Our data shows that 3.0T MRI bone models are more similar to CT bone models than previously validated 1.5T MRI bone models. This is likely due to the higher resolution of the 3T data.

Recurrence of Hamstring Injuries and Risk Factors for Partial and Complete Tears in the National Football League: An Analysis From 2009-2020.

PURPOSE: To (1) characterize hamstring injury (HSI) recurrence rates across the 2009-2010 to 2019-2020 NFL seasons and (2) to identify HSI recurrence risk factors among positions and determine the weekly return to play (RTP) recurrence risk. We hypothesized that older players, skill position players, and players returning to play faster were most at risk. METHODS: Public data from the 2009-2010 to 2019-2020 seasons were reviewed to identify HSIs. Player characteristics were collected before and two seasons following injury. A week-by-week analysis of recurrence risk was evaluated with linear and logarithmic trendlines of the best fit. RESULTS: A total of 2075 HSI were identified with a mean age of 26.2 years (20.0-43.0), BMI of 29.6 (22.7-43.5), and 3.4 seasons of experience (0-17), with 1826 strains (88.0%), 236 partial tears (11.3%), and 13 complete tears (0.63%). Of the 2075 injuries, 796 (38.4%) were recurrent, with 247 (11.9%) being a same-season reinjury. Logistic regression found that fewer weeks before RTP, in-game injury, and lower BMI were risk factors for same-season recurrence. For any recurrence, logistic regression identified more recent year of injury, lower BMI, and longer playing experience as significant risk factors. Wide receivers were found to be at risk for same-season recurrence. For any-season recurrence, defensive backs, linebackers, running backs, tight ends, and wide receivers were at risk. Week-by-week recurrence analysis determined the greatest risk to be when players returned within 2 weeks (13.4%). CONCLUSIONS: There is a high rate of HSI recurrence in the NFL. Risk factors for same-season injury include shorter time to RTP, in-game injury, lower BMI, and playing wide receiver. Risk factors for any-season recurrence were more recent year of injury, lower BMI, longer playing experience, and playing defensive back, linebacker, running back, tight end, or wide receiver. The greatest risk factor for HSI recurrence was RTP within 2 weeks.

Noninvasive shape-fitting method quantifies cam morphology in femoroacetabular impingement syndrome: Implications for diagnosis and surgical planning.

There are considerable limitations associated with the standard 2D imaging currently used for the diagnosis and surgical planning of cam-type femoroacetabular impingement syndrome (FAIS). The aim of this study was to determine the accuracy of a new patient-specific shape-fitting method that quantifies cam morphology in 3D based solely on preoperative MRI imaging. Preoperative and postoperative 1.5T MRI scans were performed on n = 15 patients to generate 3D models of the proximal femur, in turn used to create the actual and the virtual cam. The actual cams were reconstructed by subtracting the postoperative from the preoperative 3D model and used as reference, while the virtual cams were generated by subtracting the preoperative 3D model from the virtual shape template produced with the shape-fitting method based solely on preoperative MRI scans. The accuracy of the shape-fitting method was tested on all patients by evaluating the agreement between the metrics of height, surface area, and volume that quantified virtual and actual cams. Accuracy of the shape-fitting method was demonstrated obtaining a 97.8% average level of agreement between these metrics. In conclusion, the shape-fitting technique is a noninvasive and patient-specific tool for the quantification and localization of cam morphology. Future studies will include the implementation of the technique within a clinically based software for diagnosis and surgical planning for cam-type FAIS.

MRI-- and CT--based metrics for the quantification of arthroscopic bone resections in femoroacetabular impingement syndrome.

The purpose of this in vitro study was to quantify the bone resected from the proximal femur during hip arthroscopy using metrics generated from magnetic resonance imaging (MRI) and computed tomography (CT) reconstructed three-dimensional (3D) bone models. Seven cadaveric hemi-pelvises underwent both a 1.5 T MRI and CT scan before and following an arthroscopic proximal femoral osteochondroplasty. The images from MRI and CT were segmented to generate 3D proximal femoral surface models. A validated 3D--3D registration method was used to compare surface--to--surface distances between the 3D models before and following surgery. The new metrics of maximum height, mean height, surface area and volume, were computed to quantify bone resected during osteochondroplasty. Stability of the metrics across imaging modalities was established through paired sample t--tests and bivariate correlation. Bivariate correlation analyses indicated strong correlations between all metrics (r = 0.728--0.878) computed from MRI and CT derived models. There were no differences in the MRI- and CT-based metrics used to quantify bone resected during femoral osteochondroplasty. Preoperative- and postoperative MRI and CT derived 3D bone models can be used to quantify bone resected during femoral osteochondroplasty, without significant differences between the imaging modalities.

Patients With a High Femoroepiphyseal Roof With Concomitant Borderline Hip Dysplasia and Femoroacetabular Impingement Syndrome Do Not Demonstrate Inferior Outcomes Following Arthroscopic Hip Surgery.

PURPOSE: The purpose of this study was to compare outcomes after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) in patients with borderline hip dysplasia and hip instability defined radiographically using the femoroepiphyseal acetabular roof (FEAR) index and in patients without radiographic evidence of hip instability. METHODS: Data from consecutive patients with borderline hip dysplasia (lateral center edge angle between 18˚-25˚) who underwent primary hip arthroscopy between April 2012 and June 2017 for the treatment of FAIS were analyzed. Baseline demographic data, radiographic parameters, preoperative, and 2-year postoperative patient-reported outcome measures were collected. The FEAR index was measured by 3 different observers. Patients with an average FEAR index ≥2˚ were categorized as having radiographic evidence of instability as previously published. The analysis was powered to detect a minimal clinically important difference (MCID) for each outcome score. Statistical analysis was performed as appropriate to compare patients with FEAR index ≥2 and <2°. RESULTS: A total of 140 patients met the inclusion criteria. The average age and body mass index of included patients was 31.7 ± 13.2 (P < .325) years and 25.1 ± 5.6 kg/m2 (P < .862). There were no statistically significant demographic differences between the groups. Nineteen (13.0%) patients were found to have a FEAR index of over 2˚. The FEAR index <2° and FEAR index ≥2° groups had a mean preoperative FEAR index (standard deviation, range) of -7.0 (5.2, -26.8 to 1.9) and 4.8 (2.5, 2.0-11.8), respectively. The interrater intraclass correlation coefficient was 0.96. Postoperative patient-reported outcomes and rates of MCID and patient-acceptable symptomatic state achievement were not statistically different between the radiographically stable and unstable groups. (p>0.05 for all). CONCLUSION: Patients with borderline hip dysplasia and radiographic evidence of hip instability, as measured by the FEAR index (≥2°), achieve similar improvement in 2-year outcomes compared to those with radiographically stable hips after arthroscopic treatment of FAIS. CLINICAL RELEVANCE: Retrospective Level III cohort study.

Assessment of Femoral Torsion on Magnetic Resonance Imaging is More Reliable Using Axial-Oblique Sequences Compared With Standard Axial Slices in Patients With Femoroacetabular Impingement Syndrome.

PURPOSE: To determine the agreeability of femoral torsion measurements on axial and oblique axial magnetic resonance imaging (MRI) sequences in patients with femoroacetabular impingement syndrome (FAIS). METHODS: Patients who underwent primary hip arthroscopy for FAIS between January 2012 to January 2019 were identified. Inclusion criteria were all patients with an MRI scan containing the pelvis and knee imaging. MRI-based measurements of femoral torsion were performed on axial and oblique-axial slices by 2 raters, and inter-rater and intrarater reliability was assessed. Bland Altman plots were constructed to evaluate the agreeability between femoral torsion measurements performed using axial and oblique-axial slices. Bivariate correlation analyses were performed to assess the relationship between measurement methods on each respective scan. A linear regression was performed between measurements performed using axial and oblique-axial sequences. RESULTS: A total of 164 patients were included. The mean true-axial and oblique axial femoral torsion were 12.2° ± 9.9° and 11.1° ± 9.2°, respectively. The intrarater reliability for axial and oblique-axial measurements were 0.993 and 0.997, respectively. The inter-rater reliability for axial and oblique-axial measurements were 0.925 and 0.965, respectively. The number of differences within the limits of agreement for axial and oblique-axial femoral torsion measurements was 58.54%. On Pearson correlation analysis, strong positive correlations were found between oblique-axial measurements at multiple time points (r = 0.994, P < .001), as well as axial measurements at multiple time points (r = 0.986, P < .001). A strong positive correlation was found between axial and oblique-axial measurements (r = 0.894, P < .001). A significant regression equation indicated that for each additional increase in axial femoral torsion, the oblique-axial femoral torsion increased 0.837 (95% confidence interval 0.772-0.901). CONCLUSIONS: Femoral torsion values measured on oblique-axial sequences are smaller than on true-axial sequences. Femoral torsion measurements on axial and oblique-axial MRI sequences exhibit poor agreement. Oblique-axial sequences demonstrated greater measurement consistency at multiple timepoints. When evaluating torsional measurements, it is important to delineate which axial sequence was used, especially in patients with suspected severe femoral antetorsion. Standardization of MRI femoral version protocols within one's practice can ensure more consistent decision-making, especially in patients with suspected femoral antetorsion. LEVEL OF EVIDENCE: Retrospective cohort, level III.

Arthroscopic Treatment of Femoroacetabular Impingement Using Labral Reconstruction with Capsular Autograft.

The acetabular labrum is essential for stability during physiologic motion of the hip. Labral repairs frequently are attempted in cases of primary tears, although labral reconstruction is an important alternative in the revision setting or in the primary setting when the tissue is unsalvageable. Labral reconstruction has been shown to restore the hip's suction-seal and fluid pressurization to that of the premorbid state, and cohort studies have demonstrated significantly improved patient-reported outcomes at midterm follow-up. Notably, the cost is of consideration during any reconstruction, and techniques have been described using both allograft and autograft sources. Autograft sources include the iliotibial band, ligamentum teres, gracilis tendon, and hip capsule. A previously described technique using the capsule was noted to hinder routine capsular closure. We present an alternative method for labral reconstruction using hip capsular tissue that is easily performed and allows for routine capsular closure.

Clinically Significant Outcome Improvement After Hip Arthroscopy in Patients With Femoroacetabular Impingement Syndrome and Severe Femoral Torsion.

BACKGROUND: The influence of femoral torsion on clinically significant outcome improvement after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) has not been well-studied. PURPOSE: To quantify femoral torsion in FAIS patients using magnetic resonance imaging (MRI) and explore the relationship between femoral torsion and clinically significant outcome improvement after hip arthroscopy. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Included were patients who underwent hip arthroscopy for FAIS between January 2012 and August 2018 and had 2-year follow-up and preoperative MRI scans containing transcondylar slices of the knee. Participants were categorized as having severe retrotorsion (SR; <0°), normal torsion (NT; 0°-25°), and severe antetorsion (SA; >25°) as measured on MRI. Patient-reported outcomes (PROs) included the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, modified Harris Hip Score, 12-item International Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain and satisfaction. Achievement of Patient Acceptable Symptom State (PASS) and substantial clinical benefit (SCB) were analyzed among cohorts. RESULTS: Included were 183 patients (SR, n = 13; NT, n = 154; SA, n = 16) with a mean age, body mass index, and femoral torsion of 30.6 ± 12.1 years, 24.0 ± 4.4 kg/m2, and 12.55° ± 9.58°, respectively. The mean torsion was -4.5° ± 2.6° for the SR, 12.1° ± 6.8° for the NT, and 31.0° ± 3.6° for the SA group. There were between-group differences in the proportion of patients who achieved PASS and SCB on the iHOT-12, pain VAS, and any PRO (P < .05). Post hoc analysis indicated that the SA group achieved lower rates of PASS and SCB on the iHOT-12 and pain VAS, and lower rates of PASS on any PRO versus the SR group (P < .05); the SR group achieved higher rates of PASS and SCB on pain VAS scores versus the NT group (P = .003). CONCLUSION: The orientation and severity of femoral torsion during hip arthroscopy influenced the propensity for clinically significant outcome improvement. Specifically, patients with femoral retrotorsion and femoral antetorsion had higher and lower rates of clinically significant outcome improvement, respectively.

Association Between Orientation and Magnitude of Femoral Torsion and Propensity for Clinically Meaningful Improvement After Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Computed Tomography Analysis.

BACKGROUND: Femoral torsion imaging measurements and classifications are heterogeneous throughout the literature, and the influence of femoral torsion on clinically meaningful outcome improvement after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) has not been well studied. PURPOSE: To (1) perform a computed tomography (CT)-based analysis to quantify femoral torsion in patients with FAIS and (2) explore the relationship between the orientation and magnitude of femoral torsion and the propensity for clinically meaningful outcome improvement after hip arthroscopy. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Consecutive patients who underwent hip arthroscopy for FAIS between January 2012 and April 2018 were identified. Inclusion criteria were the presence of preoperative CT imaging with transcondylar slices of the knee and minimum 2-year outcome measures. Exclusion criteria were revision hip arthroscopy, Tönnis grade >1, congenital hip condition, hip dysplasia (lateral center-edge angle <20°), and concomitant gluteus medius or minimus repair. Torsion groups were defined as severe retrotorsion (SR; <0°), moderate retrotorsion (MR; 0°-5°), normal torsion (N; 5°-20°), moderate antetorsion (MA; 20°-25°), and severe antetorsion of antetorsion (SA; >25°). Treatment did not differ based on femoral torsion. Patient characteristics and clinical outcomes were analyzed, including the Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), international Hip Outcome Tool (iHOT-12), visual analog scale (VAS) for pain, and VAS for satisfaction. Achievement of the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) by torsion stratification was analyzed using the chi-square test. Inter- and intrarater reliabilities for CT measurements were 0.980 (P < .001) and 0.974 (P < .001), respectively. RESULTS: The study included 573 patients with a mean ± SD age and body mass index of 32.6 ± 11.8 years and 25.6 ± 10.6, respectively. The mean ± SD femoral torsion for the study population was 12.3°± 9.3°. After stratification, the number of patients within each group and the mean ± SD torsion for each group were as follows: SR (n = 36; -6.5°± 7.1°), MR (n = 80; 2.8°± 1.4°), N (n = 346; 12.3°± 4.1°), MA (n = 64; 22.2°± 1.4°), and SA (n = 47; 30.3°± 3.7°). No significant differences in age, body mass index, sex, tobacco use, workers' compensation status, or participation in physical activity were observed at baseline. No significant differences were seen in pre- and postoperative VAS pain, mHHS, HOS-ADL, HOS-SS, iHOT-12, or postoperative VAS satisfaction among the cohorts. Furthermore, no statistically significant differences were found in the proportion of patients who achieved the MCID or the PASS for any outcome among the groups. CONCLUSION: The orientation and severity of femoral torsion at the time of hip arthroscopy for FAIS did not influence the propensity for clinically significant outcome improvement.

High Rate of Full Duty Return to Work After Hip Arthroscopy for Femoroacetabular Impingement Syndrome in Workers Who Are Not on Workers' Compensation.

BACKGROUND: Femoroacetabular impingement syndrome (FAIS) is an increasingly common diagnosis among working-age adults. Hip arthroscopy provides reliable improvements in pain and may allow patients to return to physical activities. No study to date has evaluated return to work (RTW) among a general population of adults after arthroscopic surgery for FAIS. PURPOSE: To evaluate (1) patients' rate of RTW, (2) time required to RTW, and (3) factors correlated with time required to RTW after arthroscopic surgery for symptomatic FAIS. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Consecutive patients aged 25 to 59 years who underwent arthroscopic surgery for FAIS between June 2018 and December 2018 were reviewed. Workers' compensation cases and patients with <1-year follow-up were excluded. The following were collected at a minimum of 1 year postoperatively: demographics, employment characteristics, Hip Outcome Score (HOS; Activities of Daily Living and Sports Specific subscales), modified Harris Hip Score, 12-Item International Hip Outcome Tool (iHOT-12), visual analog scale for pain, and RTW characteristics. Work physical activity level was classified as sedentary, light, moderate, heavy, or very heavy per established criteria. RESULTS: A total of 97 patients were selected through inclusion and exclusion criteria. RTW surveys were collected for 79 (81.4%), and 61 were employed preoperatively. Time worked per week was 42.8 ± 12.5 hours (mean ± SD). Patients' work level was most commonly classified as sedentary (42.6%), followed by moderate (24.6%). All 61 (100%) patients returned to work at a mean 7.3 weeks (range, <1-88 weeks) postoperatively. Sixty patients (95.2%) returned to full duty. Time required to full duty RTW was strongly correlated with expected time off from work (r = 0.900; P < .0001) and moderately correlated with work classification (r = 0.640; P = .0001). All patients had significant pre- to postoperative improvements in the HOS-Activities of Daily Living (64.8 ± 15.3 to 87.1 ± 12.2; P < .001), HOS-Sports Specific (42.8 ± 18.8 to 76.7 ± 16.5; P < .001), iHOT-12 (31.3 ± 18.8 to 69.3 ± 21.1; P < .001), modified Harris Hip Score (61.8 ± 12.1 to 80.3 ± 14.1; P < .001), and visual analog scale for pain (5.19 ± 2.11 to 2.40 ± 1.96; P < .001). CONCLUSION: Patients undergoing arthroscopic treatment for FAIS demonstrated a high rate of RTW at a mean of <2 months postoperatively. A patient's expected time off from work and the level of physical demands required for work were highly associated with time required to RTW. These results are valuable for orthopaedic surgeons, patients, and employers when establishing a timeline for expected RTW after surgery.

Cartilage-Preserving Arthroscopic-Assisted Radiofrequency Ablation of Periacetabular Osteoid Osteoma in a Young Adult Hip.

Osteoid osteomas are benign bone lesions that commonly occur in the lower extremities and spine, with the radiographic evidence of a central nidus surrounded by circumferential reactive bone. Although nonsteroidal anti-inflammatory drugs can provide symptomatic relief and are used as an important diagnostic tool, surgical intervention is the definitive treatment. Arthroscopic-assisted radiofrequency ablation has been shown to be an effective technique to directly visualize and treat the lesion while minimizing damage to the articular cartilage.