Femoroacetabular Impingement Deformities Research Articles

Femoroacetabular Variations Are Predisposing Factors for Traumatic Posterior Hip Dislocation.

Although high-energy trauma mechanisms are generally considered to cause traumatic posterior hip dislocations, femoroacetabular variations are assumed to contribute to low-impact hip dislocations. Thus, the present study aimed to identify morphologic femoral and acetabular risk factors that may also contribute to posterior hip dislocations in high-energy trauma mechanisms. The acetabular and femoral morphology of 83 hips with a traumatic posterior dislocation following a high-energy trauma mechanism were analyzed and matched to a control group of 83 patients who sustained high-energy trauma without a hip injury. The lateral center-edge angle, acetabular index, acetabular depth/width ratio, cranial and central acetabular version angles, and the anterior and posterior acetabular sector angles were measured on computed tomography to quantify femoroacetabular impingement (FAI) morphology, acetabular version, and coverage. The caput-collum-diaphyseal angle and the alpha angles in the coronal and axial planes were measured to detect cam-type FAI deformity. A receiver operating characteristic curve was utilized to determine threshold values for an increased risk of hip dislocation. Acetabular retroversion and posterior acetabular undercoverage were significantly increased in patients with hip dislocations compared with controls (p < 0.001). The central acetabular version angle and posterior acetabular sector angle that indicated an increased risk of hip dislocation were ≤9° and ≤90°, respectively. Cam-type FAI deformity and coxa valga were significantly increased in the dislocation group (p < 0.001). The anterolateral alpha angle that indicated an increased dislocation risk was ≥47°. Acetabular retroversion, posterior acetabular undercoverage, and cam-type FAI morphology may be risk factors contributing to traumatic posterior hip dislocation in high-energy trauma mechanisms. Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Prevalence of hip femoroacetabular impingement deformities in high-level (La Liga) male professional football players.

Femoroacetabular impingement (FAI) is considered one of the main causes of hip osteoarthritis in young adults, especially in athletes. In recent years, morphological changes in FAI in the hip have been linked to early and intense sports participation, but studying top-level athlete samples is not easy. This paper presents the prevalence of FAI radiological markers in 120 active white male professional football players in the Spanish First Division League (La Liga) and compares the morphological changes with those of a control group of healthy individuals without significant sport activity. The precontract medical evaluation hip X-rays of 120 white male professional football players from four different First Division Spanish football teams were prospectively filed and retrospectively reviewed by a dedicated skeletal radiologist. The footballers' hip X-rays were compared with those of a control group of 80 healthy individuals (age-sex matched) without significant sport activity (obtained from routine work medical checks). The femoral head-neck deformity associated with the Cam type of femoroacetabular impingement was observed in 61.6% of professional football players and only in 11.6% of the control group (p <0.01). The presence of "herniation pit" (11.6%) and os acetabuli (13.3%) also reached statistical significance in the professional football players group. In the other analyzed parameters, no statistically significant differences between the groups were observed. White professional top-level football players have an increased incidence of abnormal lateral epiphyseal extension ("pistol grip deformity"), os acetabuli and herniation pits.

The Effect of Pelvic Incidence on Outcomes Following Hip Arthroscopy for Femoroacetabular Impingement and Acetabular Labral Tears

Objectives: Left untreated, femoroacetabular impingement (FAI) poses an elevated risk for the early progression of degenerative joint disease. As a result, the utilization of hip arthroscopy has increased to counteract the maladaptive effects of FAI, as femoroacetabular osteoplasties have been shown to reconcile deleterious loading patterns caused by CAM and pincer lesions. However, variations in the sagittal alignment of the lumbosacral spine also pose an elevated risk for the early progression of degenerative joint disease. While femoroacetabular osteoplasties improve degenerative loading patterns caused by CAM and pincer lesions, variations in the sagittal alignment of the lumbosacral spine may continue to generate deleterious effects on the labrum, chondrolabral junction, and articular cartilage following hip arthroscopy for acetabular labral tears and FAI. Thus, the purpose of this study was to evaluate the impact of pelvic incidence (PI) on patient-reported outcomes measures (PROMs) and rates of achieving clinically meaningful outcomes following primary hip arthroscopy for acetabular labral tears and FAI. Methods: A retrospective review of a prospectively collected, single-surgeon database was performed to identify patients ≥18 years of age who underwent primary hip arthroscopy for the treatment of labral tears secondary to FAI with a minimum of 12 months of follow-up. Patients with a history of ipsilateral hip or spine surgery, absence of preoperative lumbar spine imaging, radiographic evidence of hip dysplasia or advanced hip osteoarthritis, and contraindicated spinal pathologies were excluded. PI, pelvic tilt (PT), sacral slope (SS), and acetabular version were measured on 2-D supine lumbar images, and patients were stratified into low PI (PI &lt; 45°), moderate PI (45° ≤ PI ≤ 60°), and high PI (PI &gt; 60°) cohorts. PROMs, VAS Pain, and frequencies of achieving clinically meaningful outcomes were compared between groups. PROMs and frequencies of achieving clinically meaningful outcomes were compared between cohorts using one-way analysis of variance tests and Fisher’s exact tests, respectively. Additionally, a sensitivity analysis using a linear mixed-effects model with time as a continuous variable was carried out to evaluate the weighted differences in PROM averages between cohorts. Results: A total of 74 patients undergoing primary hip arthroscopy for FAI and acetabular labral tears met eligibility criteria and were subsequently stratified into low ( n=28), moderate ( n=31), and high ( n=15) PI cohorts. The mean ± SD length of follow-up was 25.16 ± 2.91 months, and no significant differences were observed between cohorts in patient demographics. However, as expected, patients in the high PI cohort displayed significantly larger mean values for PT ( P=0.001), SS ( P&lt;0.001), acetabular version ( P&lt;.001), and acetabular inclination ( P=0.049). Moreover, despite no differences in preoperative outcome scores between cohorts, the high PI cohort displayed significantly inferior scores for all PROMs and VAS pain across 6-, 12, and 24-month follow-ups. This finding also extended to our sensitivity analysis, with the high PI cohort displaying significantly lower weighted averages in scores across all PROMs relative to the moderate PI cohort ( P≤.001 for all). Additionally, the high PI cohort demonstrated significantly lower rates of clinically meaningful outcome achievement and overall patient satisfaction at 12- and 24-month follow-ups compared to the moderate and/or low PI cohorts. No significant differences were found between cohorts in terms of revision hip arthroscopy, subsequent spine surgery, or conversion to THA. Conclusions: Following hip arthroscopy to address acetabular labral tears, patients with a high PI exhibit significantly inferior PROMs relative to those with moderate and low PI. Thus, despite addressing FAI deformities, variations in lumbosacral alignment may continue to impact patient outcomes. Although the current study design limits our ability to infer causality, the significantly greater acetabular version and inclination values observed in the high PI cohort lead us to speculate that the sagittal imbalance in the setting of a high PI places increased mechanical stress on the anterior-superior acetabulum, which portends poor outcomes following hip arthroscopy. Overall, our findings highlight the critical importance of analyzing pelvic alignment in order to prognosticate outcomes following hip arthroscopy for acetabular labral tears in the setting of FAI.

Radiographic and Dynamic Assessment for Resection of Cam Lesions in Patients With Femoroacetabular Impingement

Cam-type femoroacetabular impingement is characterized by a pathologic asphericity of the femoral head-neck junction, and arthroscopic femoral osteoplasty is indicated to correct the bony abnormality and restore normal hip mechanics when symptomatic. Residual femoroacetabular impingement deformity after arthroscopy is a leading cause of failure, and it is therefore critical to perform a thorough fluoroscopic and dynamic assessment when addressing cam deformities arthroscopically. The fluoroscopic assessment uses 6 anteroposterior views, including 3 in hip extension (30°internal rotation, neutral rotation, and 30° external rotation) and 3 in 50° flexion (neutral rotation, 40° external rotation, 60° of external rotation), performed before, during, and after the femoral resection. The dynamic assessment includes evaluation of impingement-free range of motion and "end feel" (a subjective description of the tactile feedback during assessment of hip motion), and should be performed before and after the femoral resection in 3 specific positions (extension/abduction, flexion/abduction, and flexion/internal rotation). Although the anterior aspect of the head-neck junction is readily accessed through standard arthroscopic portals with the hip in 30 to 50° of flexion, the posterolateral, posteromedial, and posterior extent of the femoral head-neck junction are challenging to address. The natural external rotation of the proximal femur during flexion and internal rotation during extension can be used to gain posterior lateral and medial access. Antero/posteromedial femoral access can be obtained with >50° of hip flexion with the burr in the anteromedial portal. Posterolateral femoral access is achieved with hip extension with the burr in the anterolateral portal, and further posterolateral access can be achieved with the addition of traction, allowing resection of posterolateral deformities extending beyond the lateral retinacular vessels while remaining proximal to the vessels. This comprehensive intraoperative fluoroscopic and dynamic assessment and surgical technique can lead to a predictable correction of most cam-type deformities.

DOES BONE TURNOVER EXPLAIN HIGH BONE DENSITY IN FEMOROACETABULAR IMPINGEMENT? AN ANALYSIS OF PET AND CT IMAGING

Femoroacetabular impingement (FAI) results from a morphological deformity of the hip and is associated with osteoarthritis (OA). Increased bone mineral density (BMD) is observed in the antero-superior acetabulum rim where impingement occurs. It is hypothesized that the repeated abnormal contact leads to damage of the cartilage layer, but could also cause a bone remodelling response according to Wolff's Law. Thus the goal of this study was to assess the relationship between bone metabolic activity measured by PET and BMD measured in CT scans.Five participants with asymptomatic cam deformity, three patients with uni-lateral symptomatic cam FAI and three healthy controls were scanned in a 3T PET-MRI scanner following injection with [18F]NaF. Bone remodelling activity was quantified with Standard Uptake Values (SUVs). SUVmax was analyzed in the antero-superior acetabular rim, femoral head and head-neck junction. In these same regions, BMD was calculated from CT scans using the calibration phantom included in the scan. The relationship between SUVmax and BMD from corresponding regions was assessed using the coefficient of determination (R2) from linear regression.High bone activity was seen in the cam deformity and acetabular rim. SUVmax was negatively correlated with BMD in the antero-superior region of the acetabulum (R2=0.30, p=0.08). SUVmax was positively correlated with BMD in the antero-superior head-neck junction of the femur (R2=0.359, p=0.067). Correlations were weak in other regions.Elevated bone turnover was seen in patients with a cam deformity but the relationship to BMD was moderate. This study demonstrates a pathomechanism of hip degeneration associated with FAI deformities, consistent with Wolff's law and the proposed mechanical cause of hip degeneration in FAI. [18F]-NaF PET SUV may be a biomarker of degeneration, especially in early stages of degeneration, when joint preservation surgery is likely to be the most successful.

Characterizing the Residual SCFE Deformity: Utility of the 45-degree Dunn View.

After treatment with in situ stabilization, slipped capital femoral epiphysis (SCFE) patients have variable degrees of deformity that can contribute to femoroacetabular impingement (FAI). To evaluate the severity of residual deformity most physicians currently use biplanar radiographs of an anteroposterior pelvis which profiles the lateral head-neck deformity and a frog lateral view which profiles the anterior head-neck deformity. However, the assessment of FAI morphology commonly relies on the 45-degree Dunn view to profile the anterolateral head-neck junction where FAI deformity is maximal. Therefore, the purpose of this study was to compare the magnitude of residual SCFE deformity detected on the frog lateral radiograph to the 45-degree Dunn radiograph. A retrospective review of radiographic images of 50 hips (47 patients) diagnosed with SCFE at a single academic institution from 2014 to 2018 was performed. The group included 25 hips evaluated postoperatively after fixation (Group 1) and 25 hips presenting with residual symptomatic SCFE deformity after previous pinning (Group 2). The alpha angle was assessed on both the 45-degree Dunn and frog lateral views for comparison. The modified Southwick slip angle was assessed on the frog lateral view only as a measure of SCFE severity. The Dunn view showed the maximal residual SCFE deformity as measured by the alpha angle in 88% (44/50) of cases. Overall, the mean alpha angle (70.7 degree vs. 60.1 degree, P <0.001) was significantly larger on the Dunn view as compared with frog lateral. Subgroup analysis showed a larger alpha angle on Dunn view compared with frog lateral in both immediate postoperative and residual SCFE deformities as well: Group 1 (69.5 degree vs. 60.9 degree, P <0.001) and Group 2 (71.9 degree vs. 59.3 degree, P <0.001). In patients with SCFE, the maximal residual deformity of the proximal femur can typically be seen on the 45-degree Dunn view, rather than on the frog lateral view. Our findings suggest the 45-degree Dunn view may be beneficial part of the postoperative assessment of SCFEs to quantify the true maximal deformity present. Level IV.

A novel concept of cam-type femoroacetabular impingement treatment with patient-specific template guided osteochondral deformity ablation.

To present a novel surgical concept for the cam-type femoroacetabular impingement (FAI) treatment and to assess and report the clinical outcomes. We performed a retrospective study of a single-surgeon case series of six hips in five consecutive male patients with symptomatic cam-type FAI, treated with the mini-open anterior hip approach with a patient-specific template (PST)-guided deformity ablation between 2015 and 2018. We assessed the hip range of motion, iHOT-33, Tegner, and EQ-5D before surgery and after a minimum follow-up of 30months. The average age was 37 ± 13.3years, average BMI was 31.1 ± 3.3kg/m2, and average pre-surgery Tönnis hip osteoarthritis (OA) grade was 1 ± 1. The average surgery duration was 71 ± eightminutes. The average estimated blood loss was 83 ± 26ml. After a mean follow-up of 50 ± 12months, we observed no OA progression with no change in Tönnis hip OA grades. Hip flexion and internal rotation significantly improved (p = 0.007; p = 0.048) from mean 98° ± 9° and 14° ± 11° to mean 113° ± 8° and 23° ± 8°, respectively. iHOT-33, Tegner, and EQ-5D improved significantly (p = < 0.001; p = 0.004; p = < 0.001) from mean 44.7 ± 12.2, 3 ± 1, and 0.513420 ± 0.101389 to mean 94 ± 2.7, 5 ± 1, and 1.000000 ± 0, respectively. One patient needed revision surgery for heterotopic ossification removal, with no sequelae at the last follow-up. Mini-open anterior hip approach with the PST-guided cam-type FAI deformity ablation presents an accurate and reproducible solution for cam-type FAI surgical treatment, with promising clinical outcomes. Using a PST in the cam-type FAI surgery may present a powerful additional tool in the existing open techniques armamentarium.

The Prevalence of Radiographic Findings of Structural Hip Deformities for Femoroacetabular Impingement in Patients With Hip Pain

Background: Radiography is the initial imaging modality used to evaluate femoroacetabular impingement (FAI), and diagnostic radiographic findings are well-established. However, the prevalence of these radiographic findings in patients with hip pain is unknown. Purpose: The purpose was 3-fold: (1) to determine the overall prevalence of radiographic FAI deformities in young patients presenting with hip pain, (2) to identify the most common radiographic findings in patients with cam-type FAI, and (3) to identify the most common radiographic findings in patients with pincer-type FAI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A geographic database was used to identify patients aged 14 to 50 years with hip pain between the years 2000 to 2016. The following were evaluated on radiographs: cam type: typical pistol grip deformity, alpha angle >55°; pincer type: crossover sign (COS), coxa profunda or protrusio acetabuli, lateral center edge angle (LCEA) ≥40°, Tönnis angle <0°; and mixed type: both cam- and pincer-type features. Posterior wall sign (PWS) and ischial spine sign (ISS) were also evaluated. The prevalence of each was determined. Descriptive statistics were performed on all radiographic variables. Results: There were 1893 patients evaluated, and 1145 patients (60.5%; 1371 hips; 374 male and 771 female; mean age, 28.8 ± 8.4 years) had radiographic findings consistent with FAI. Of these hips, 139 (10.1%) had cam type, 245 (17.9%) had pincer type, and 987 (72.0%) had mixed type. The prevalence of a pistol grip deformity and an alpha angle >55° was 577 (42.1%) and 1069 (78.0%), respectively. The mean alpha angle was 66.9°± 10.5°. The prevalence of pincer-type radiographic findings was the following: COS, 1062 (77.5%); coxa profunda, 844 (61.6%); ISS, 765 (55.8%); PWS, 764 (55.7%); Tönnis angle <0°, 312 (22.8%); LCEA ≥40°, 170 (12.4%); and protrusio acetabuli, 7 (0.5%). Conclusion: The overall prevalence of radiographic findings consistent with FAI in young patients with hip pain was 60.5%. Radiographic findings for mixed-type FAI were the most prevalent. The most common radiographic finding for cam-type FAI was an alpha angle >55°. The most common radiographic finding for pincer-type FAI was the COS.

Arthroscopic Surgery for Femoroacetabular Impingement in Skeletally Immature Athletes: Radiographic and Clinical Analysis

To evaluate radiographic and clinical outcomes after arthroscopic femoroacetabular impingement (FAI) correction in symptomatic adolescent athletes with open physes. We retrospectively reviewed radiographic and clinical outcomes in patients treated with a non-physeal-sparing arthroscopic approach for symptomatic FAI with open physes and a minimum 1-year follow-up. Specific plain radiographic and computed tomography parameters were determined, and preoperative and postoperative outcomes were prospectively evaluated with modified Harris Hip Score (mHHS), 12-Item Veterans-Rand, and pain on a visual analog scale. Thirty-seven hips (28 patients; 75% male) with a mean age of 15.9years (range, 12.8-18.3years) had imaging studies consistent with open femoral neck and iliac crest physes. The ischial tuberosity and greater trochanteric physes were open in 95% and 54% of the hips, respectively. All patients participated in organized athletics, and 50% were in multiple sports year-round. Mean follow-up was 39.8months post-arthroscopic FAI correction. There was a mean 27.7-point improvement in the mHHS (P < .001), a 4.8-point decrease in the visual analog scale for pain (P < .001), and a 15.2-point improvement in the 12-Item Veterans-Rand physical component (P < .001). Ninety-three percent of patients returned to their preinjury level of sports participation without limitations. Thirty (81.1%) patients demonstrated improvements in mHHS greater than the minimally clinically important difference (of mHHS 8 points). Two patients could not reach minimally clinically important difference because of a preoperative mHHS of > 92. There were no postoperative physeal growth arrests, growth disturbances, physeal instability, or avascular necrosis. A non-physeal-sparing arthroscopic approach for FAI in adolescents with open physes is safe and effective with no evidence of clinically relevant complication of growth arrest-related deformity or physeal instability in patients with a minimum of 1year (mean, 39.8months) of follow-up after surgery. Young, highly athletic adolescent patients with larger FAI deformities demonstrated greater outcomes improvement after arthroscopy. Level IV, therapeutic case series.

FAI SURGERY IN THE ADOLESCENT POPULATION: MILD DEFORMITIES AND LACK OF SPORTS PARTICIPATION ARE ASSOCIATED WITH AN INCREASED RISK OF TREATMENT FAILURE

Background: Femoroacetabular impingement (FAI) is as prevalent in adolescents as in adults, yet few studies have analyzed treatment outcomes in the adolescent population. The purpose of this study was to determine the clinical outcomes of FAI surgery in adolescent patients and to identify predictors of treatment failure. Methods: A cohort of 126 adolescent patients (&lt;18 years) undergoing surgery for symptomatic FAI were prospectively assessed among a larger multicenter cohort. The adolescent subgroup included 74 (58.7%) males and 52 (41.3%) females, had a mean age of 16.1 years (range 11.3-18.0), and a mean follow-up of 3.7 years. Mild cam FAI was defined by an alpha angle less than 55 degrees. Clinical outcomes were analyzed with the mHHS, HOOS (5 domains), and UCLA activity score. Failure was defined as revision surgery or clinical failure (failure to reach MCID (minimally clinically important difference) or PASS (patient acceptable symptoms state) for modified Harris Hip score. Statistical analysis was performed to identify factors significantly associated with failure. Results: There was clinically important improvement in all PROs (mHHS, all HOOS domains) for the overall cohort and 81% of patients met criteria for a successful outcome. The failure rate (revision surgery or clinical failure) of the overall cohort was 19%, including revision surgery in 8.7%. Female patients were significantly more likely than male patients to be classified as a failure (25.7% vs. 9.1%, p=0.017, OR 2.6), in part because of a lower preoperative mHHS (59.1 vs. 67.0, p&lt;0.001). Mild cam FAI (alpha less than 55 degrees) was present in 31.5% of cases including 39.1% of females and 14.5% of males. Maximal alpha angle was significantly inversely associated with the failure rate (37.5% for alpha&lt;55, 19.2% for alpha 55-63, and 6.8% for alpha&gt;63, p&lt;0.005). Non-athletes were at a significantly greater risk of failure compared to athletes (26.5% vs. 10.3%, p=0.043, OR 2.3). Multivariable logistic regression identified mild cam FAI and lack of participation in sports as predictive of failure (p=0.005 and p=0.04), while gender was no longer significantly associated with failure after controlling for other variables. Conclusions: Adolescent patients undergoing surgical treatment of FAI demonstrate significant improvement at early followup. However, mild cam FAI deformities (which are common in adolescent female patients) and lack of participation in sports are independently associated with higher rates of treatment failure. These factors associated with treatment failure should be considered in surgical treatment decision-making and patient counseling.

Vertical Extension of the T-Capsulotomy Incision in Hip Arthroscopic Surgery Does Not Affect the Force Required for Hip Distraction: Effect of Capsulotomy Size, Type, and Subsequent Repair

Background: Interportal and T-capsulotomies are popular techniques for exposing femoroacetabular impingement deformities. The difference between techniques with regard to the force required to distract the hip is currently unknown. Purpose: To quantify how increasing interportal capsulotomy size, conversion to T-capsulotomy, and subsequent repair affect the force required to distract the hip. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric hip specimens were dissected and fixed in a materials testing system, such that pure axial distraction of the iliofemoral ligament could be achieved. The primary outcome measure was the load required to distract the hip to a distance of 6 mm at a rate of 0.5 mm/s. Each hip was tested in the intact state and then sequentially under varying capsulotomy conditions: 2-cm interportal, 4-cm interportal, half-T (4-cm interportal and 2-cm T-capsulotomy), and full-T (4-cm interportal and 4-cm T-capsulotomy). After serial testing, isolated T-limb repair and then subsequent complete repair were performed. Repaired specimens underwent distraction testing as previously stated to assess the ability to restore hip stability to the native profile. Distraction force as well as the relative distraction force (percentage normalized to the intact capsule) were compared between all capsulotomy and repair conditions. Results: Increasing interportal capsulotomy size from 2 to 4 cm resulted in significantly less force required to distract the hip (P < .001). The largest relative decrease in force was seen between the intact state (274.6 ± 71.2 N; 100%) and 2-cm interportal (209.7 ± 73.2 N; 76.4% ± 15.6%; P = .0008). There was no significant mean difference in distraction force when 4-cm interportal (160.4 ± 79.8 N) was converted to half-T (140.7 ± 73.5 N; P = .270) and then full-T (112.0 ± 70.2 N; P = .204). When compared with the intact state, isolated T-limb repair partially restored stability (177.3 ± 86.3 N; 63.5% ± 19.8%; P < .0001), while complete repair exceeded native values (331.7 ± 103.7 N; 122.7% ± 15.1%; P = .0008). Conclusion: The conversion of interportal capsulotomy to T-capsulotomy did not significantly affect the force required to distract the hip in a cadaveric model. However, larger interportal capsulotomies resulted in significant stepwise decreases in distraction force. When performing interportal or T-capsulotomy, the iliofemoral ligament strength is significantly decreased, but complete capsular repair demonstrated the ability to restore joint stability to the native, intact hip. Clinical Relevance: Increasing interportal capsulotomy size decreases the force required to distract the hip. In an effort to maximize visualization and minimize the magnitude of iliofemoral ligament fibers cut, many surgeons have moved from extended interportal capsulotomy to T-capsulotomy. Interportal and T-capsulotomies result in equivalent hip distraction, partial capsular repair marginally improves hip stability, and only complete repair has the ability to restore the hip to its native biomechanical profile.

Bone density changes following surgical correction of femoroacetabular impingement deformities

Femoroacetabular impingement (FAI) involves abnormal hip biomechanics due to deformities and is associated with osteoarthritis. Bone mineral density (BMD) in the acetabulum is higher in subjects with convex femoral (cam) FAI deformities compared to control subjects. The objective of this study was to assess post-operative changes of BMD with and without surgical correction of the cam deformity. Thirteen patients with bilateral cam deformities but unilateral symptoms underwent pre-operative and follow-up computed tomography (CT) scans of both hips. The deformity was surgically removed from the symptomatic hip. BMD was measured in regions of interest (ROI) around the superior acetabulum from CT scans at both time points. The contralateral untreated hip was used as a within-patient control. Changes in BMD were assessed by two-way repeated measures ANOVA (side, time) and paired t-tests. A greater BMD decrease was seen in the treated compared to the untreated hip (P<0.0018). BMD within the superior acetabulum decreased by 39mg/cc on the treated side (P<0.0001) but only 9mg/cc (P=0.15) in the untreated contralateral hip. These changes represent 7.1% and 1.7% of the pre-operative BMD on the respective sides. BMD decreased in the treated hip, suggesting a positive effect of surgical correction in relieving stresses within the hip joint. Longer term follow-up is required to assess the ultimate fate of the articular cartilage within the joint. This study showed that surgical correction of the cam deformity in patients with FAI may alter the pathological biomechanics within the joint.

Extra-articular Debridement of Hip Joint for Management of Anterior Hip Pain

Groin pain is a common problem that is known to be a complex issue. The wide variety of possible pathologies in numerous anatomical structures contributes to this complexity. For patients who have anterior hip pain in Patrick's test and tenderness at Scarpa's triangle, we perform periarticular debridement based on the hypothesis that rectus femoris tendinosis, subacute/chronic fibrosis of the anterior inferior iliac spine fat pad, and gluteal muscle adhesion are responsible for such anterior hip pain. This Technical note illustrates the surgical procedure of periarticular debridement for extra-articular pathology-associated anterior hip pain. Repair of the injured labrum and correction of femoroacetabular impingement deformity have never been performed in this cohort. Arthroscopic periarticular debridement is a reliable surgical technique that can relieve anterior hip pain and provide a rapid to return to normal activities.

The Anteroposterior Pelvic Radiograph: Acetabular and Femoral Measurements and Relation to Hip Pathologies.

➤ A proper technique is critically important for accurate interpretation of the anteroposterior radiograph, with a true anteroposterior radiograph of the pelvis made with the patient in the supine or standing position with a tube-to-image distance of 120 cm and a photon beam centered midway between the pubic symphysis and the top of the iliac crests.➤ Frequent characteristics of developmental dysplasia that may be seen on an anteroposterior pelvic radiograph are a hypoplastic acetabular weight-bearing zone, steeply sloped acetabular roof, lateralized center of rotation, acetabular anteversion or retroversion in the presence of a hypovolemic acetabulum, and coxa valga.➤ Increased depth, femoral head overcoverage, and/or abnormal acetabular version (typically retroversion) are the main etiologies of pincer-type femoroacetabular impingement (FAI).➤ Cam-type FAI deformities are represented by global deformities such as femoral head asphericity and diminished head-neck offset.➤ Commonly utilized grading systems of osteoarthritis evaluate the hip for evidence of joint-space narrowing, subchondral sclerosis and cyst formation, osteophyte development, and femoral head deformity.

Bony Morphology of Femoroacetabular Impingement in Young Female Dancers and Single-Sport Athletes.

Background:Femoroacetabular impingement (FAI) is a painful and limiting condition of the hip that is often seen in young athletes. Previous studies have reported a higher prevalence of this disorder in male athletes, but data on the structural morphology of adolescent and young adult female athletes, specifically those involved in dance, are lacking.Purpose:(1) To investigate the radiographic morphology of FAI deformities in adolescent and young adult female single-sport dance and nondance athletes and (2) to examine the differences in the radiographic findings between these 2 groups.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A retrospective chart review of 56 female single-sport athletes 10 to 21 years of age with a diagnosis of FAI within a single-sports medicine division of a pediatric academic medical center was performed. Acetabular index (AI), lateral center-edge angle (LCEA), crossover sign, and ischial spine sign were measured bilaterally on anteroposterior radiographs; alpha angle (AA) was measured on lateral films, and anterior center-edge angle (ACEA) was measured on false-profile films. Independent t tests and Mann-Whitney U tests were used to compare mean angle measurements between dance and nondance athletes. Dichotomized categorical variables and crossover and ischial spine signs were analyzed between dance and nondance athletes by applying a chi-square test. Statistical significance was set as P < .05 a priori.Results:Significant differences in angle measurements were noted. AA was significantly lower in the dancers compared with the nondance athlete group (49.5° ± 6.0° vs 53.9° ± 7.3°, P = .001). The LCEA and ACEA of dance athletes were significantly greater compared with nondance athletes (33.8° ± 6.7° vs 30.9° ± 5.8° [P = .016] and 36.0° ± 8.1° vs 32.3° ± 7.0° [P = .035], respectively). No significant difference in AI was seen between the 2 cohorts (5.0° ± 4.0° for dancers vs 5.9° ± 3.4° for nondancers, P = .195).Conclusion:Significant differences existed in the radiographic bony morphology of young female single-sport dance athletes compared with nondance athletes with FAI. In dance athletes, symptoms were seen in the setting of normal bony morphology.

Preoperative Symptoms in Femoroacetabular Impingement Patients Are More Related to Mental Health Scores Than the Severity of Labral Tear or Magnitude of Bony Deformity

BackgroundThe purpose of this study was to determine the relationships between patient factors, mental health status, the condition of the local tissue, magnitude of bony deformity, and preoperative symptoms in a series of femoroacetabular impingement (FAI) patients. MethodsFrom our prospective outcomes registry, we identified 64 patients with arthroscopically-treated labral tears and cam deformities. We assessed the correlations between patient factors (age, sex, body mass index, level of education), surgical findings (size of labral tear, presence of chondral lesions), mental health factors (VR-12 mental component score [MCS], depression, and preoperative use of psychotropic and/or opioid drugs), magnitude of FAI deformity (alpha and lateral center edge angles), and preoperative hip dysfunction and osteoarthritis outcome score (HOOS) subscales. Patient factors, surgical and radiographic findings, and preoperative HOOS scores were compared between patients with low and high MCS. ResultsNeither hip pathology nor patient-related factors significantly correlated with HOOS scores. On the contrary, MCS significantly correlated with HOOS symptom (ρ = 0.45, P < .001) and pain scores (ρ = 0.52, P < .001). Low MCS patients had significantly lower preoperative scores for all 5 HOOS subscales (P ≤ .002) and more frequent chondral lesions and comorbid depression (P ≤ .01). ConclusionSymptom severity was significantly more related to mental health status than either the size of labral tear or FAI deformity. Patients with low MCS had significantly worse preoperative pain and self-reported function, and a greater prevalence of concomitant chondral lesions. Future studies are necessary to determine if earlier surgical treatment or preoperative psychological and/or pain coping interventions may improve outcomes for those with low MCS.

Properties of the cartilage layer from the cam-type hip impingement deformity

Femoro-acetabular impingement (FAI) is associated with significant acetabular cartilage damage and degenerative arthritis. To understand the contact stress and thus biomechanical mechanisms that may contribute to degeneration, the material behaviour of the cartilage layer is required. The objective of this study is to determine the fibril-reinforced poroelastic properties and composition of cartilage from cam deformities and to compare to those of normal cartilage. Patients undergoing surgical treatment of a symptomatic cam FAI deformity were recruited from the clinical practice of one of the authors. Osteochondral specimens were retrieved from the deformity during surgery using a trephine. Control specimens were retrieved from the anterior femoral head bearing surface during autopsy procedures. Indentation stress-relaxation tests were performed to determine the modulus (ES), Poisson’s ratio (ν) and permeability (k0) of the poroelastic component, and the strain-independent (E0) and -dependent (Eε) moduli of the fibril-reinforcement using finite element analysis and optimization. Safranin-O staining was used to quantify proteoglycan content. ES and ν were 71% and 37% lower, respectively, in Cam specimens compared to controls, and k0 was approximately triple that of Control specimens (p<0.05). No significant differences were seen in the fibrillar components, E0 and Eε. Proteoglycan content was substantially depleted in Cam specimens, and was correlated with ES, ν and k0. This study showed that cartilage from the cam deformity exhibits severe degeneration in terms of the mechanical behaviour and composition changes, and is consistent with osteoarthritis. This further supports the hypothesis that FAI is a cause of hip osteoarthritis.

Outcome of Hip Impingement Surgery: Does Generalized Joint Hypermobility Matter?

Background: Generalized joint hypermobility (JH) might negatively influence the results of surgical femoroacetabular impingement (FAI) treatment, as JH has been linked to musculoskeletal pain and injury incidence in athletes. JH may also be associated with worse outcomes of FAI surgery in thin females. Purpose: To (1) determine the results of FAI surgery at a minimum 2-year follow-up by means of patient-reported outcome measures (PROMs) and failure rates, (2) assess the prevalence of JH in FAI patients and its effect on outcomes, and (3) identify other risk factors associated with treatment failure. Study Design: Cohort study; Level of evidence, 3. Methods: We included 232 consecutive patients (118 females; mean age, 36 years) with 244 hips surgically treated for symptomatic FAI between 2010 and 2012. All patients completed different PROMs preoperatively and at a mean follow-up of 3.7 years. Satisfaction questions were used to define subjective failure (answering any of the 2 subjective questions with dissatisfied/very dissatisfied and/or didn’t help/made things worse). Conversion to total hip replacement (THR) was defined as objective failure. JH was assessed using the Beighton score. Results: All PROM values significantly (P < .001) improved from preoperative measurement to follow-up (Oxford Hip Score: 33.8 to 42.4; University of California at Los Angeles Activity Scale: 6.3 to 7.3; EuroQol−5 Dimension Index: 0.58 to 0.80). Overall, 34% of patients scored ≥4 on the Beighton score, and 18% scored ≥6, indicating generalized JH. Eleven hips (4.7%) objectively failed and were converted to THR. Twenty-four patients (10.3%) were considered as subjective failures. No predictive risk factors were identified for subjective failure. Tönnis grade significantly (P < .001) predicted objective failure (odds ratio, 13; 95% CI, 4-45). There was a weak inverse association (r = −0.16 to −0.30) between Beighton scores and preoperative PROM values. There were no significant associations between Beighton scores and postoperative PROM values or subjective failure rates, but patients who objectively failed had lower Beighton scores than did nonfailures (1.6 vs 2.6; P = .049). Conclusion: FAI surgery yielded favorable outcomes at short- to midterm follow-up. JH as assessed by the Beighton score was not consistently associated with subjective and objective results. Joint degeneration was the most important risk factor for conversion to THR. Although statistical significance was not reached, female patients with no joint degeneration, only mild FAI deformity, and higher Oxford scores at the time of surgery seemed to be at increased risk for subjective dissatisfaction.

Femoroacetabular Impingement Is Associated With Sports-Related Posterior Hip Instability in Adolescents

Background: Femoroacetabular impingement (FAI) deformity has been associated with posterior hip instability in adult athletes. Purpose: To determine if FAI deformity is associated with posterior hip instability in adolescents, the femoral head-neck junction or acetabular structure in a cohort of adolescent patients who sustained a low-energy, sports-related posterior hip dislocation was compared with that in a group of healthy age- and sex-matched controls with no history of hip injury or pain. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We identified 12 male patients (mean age, 13.9 years; range, 12-16 years) who sustained a sports-related posterior hip dislocation and underwent a computed tomography (CT) scan after closed reduction. For each patient, 3 age- and sex-matched healthy controls were identified. Femoral head-neck type was assessed by measurement of the alpha angle on the radially oriented CT images at the 12-, 1-, 2-, and 3-o’clock positions. Age, body mass index (BMI), alpha angle at each position, acetabular version, Tönnis angle, and lateral center-edge angle (LCEA) on the involved hip in the dislocation group were compared with those of the matched controls using a mixed-effects model. A logistic regression analysis using a generalized estimating equation was used to compare the percentage of subjects with cam-type FAI deformity (alpha angle >55°) in each group. Results: The dislocation and control groups were similar in age distribution and BMI (P > .05). The mean alpha angles were statistically significantly higher in the dislocation group compared with the control group at the superior (46.3° ± 1.1° vs 42.7° ± 0.6°; P = .0213), superior-anterior (55.5° ± 1.9° vs 46.0° ± 1.3°; P = .0005), and anterior-superior (54.9° ± 1.5° vs 48.9° ± 1.0°; P = .0045) regions. Cam deformity was present in a larger proportion of patients in the dislocation group than in the control group (P < .0035). An alpha angle greater than 55° was present in 16.7% of the dislocation group and 0% of the control group at the 12-o’clock position (P = .1213), 41.7% versus 0% at the 1-o’clock position (P = .0034), 58% versus 6% at the 2-o’clock position (P = .0004), and 25% versus 2.8% at the 3-o’clock position (P = .0929). Acetabular anteversion was lower in the dislocation group (9.6° ± 1.4°) compared with the control group (15.1° ± 0.8°) (P = .0068). Mean acetabular LCEA was within a normal range in both groups. Conclusion: A significantly higher mean alpha angle from the superior to the anterior-superior regions of the femoral head-neck junction and lower acetabular version were found in adolescents who sustained low-energy, sports-related posterior hip dislocations.

Femoral subchondral bone properties of patients with cam-type femoroacetabular impingement

Morphological deformities of the hip, such as femoroacetabular impingement (FAI) may be responsible for up to 80% of hip osteoarthritis. In cam type FAI, the pathomechanism has been attributed to repeated abnormal contact between the femur and the antero-superior acetabular rim, resulting in cartilage and labrum degeneration. Subchondral bone stiffness likely plays a major role in the process, but little is known of the mechanical properties of the cam deformity. The purpose of this study was to determine tissue modulus and the trabecular micro-architecture of the subchondral bone of the cam deformity of patients undergoing resection surgery as well as comparing these parameters to healthy aged matched controls. Twelve osteochondral bone biopsies were obtained from symptomatic FAI patients and ten osteochondral control specimens were harvested from cadaveric femurs. A combination of mechanical testing, micro-CT and finite element (FE) analysis were used to determine tissue modulus, bone volume fraction, trabecular thickness, trabecular and spacing, and trabecular number. The mean tissue modulus of the cam-type FAI deformities (E=5.4GPa) was significantly higher than normal controls (E=2.75GPa, P=0.038), but no statistically significant differences were found in bone micro-architectural parameters. The data suggests that subchondral bone of the cam deformity consists of older secondary mineralized bone. This supports the notion that the cam deformity is a primary malformation with intrinsic biomechanical abnormalities rather than a secondary deformity as part of the degenerative process of the covering cartilage or remodeling due to repeated impingement.