High prevalence of hip lesions secondary to arthroscopic over- or undercorrection of femoroacetabular impingement in patients with postoperative pain

Objectives To compare the prevalence of pre- and postoperative osseous deformities and intra-articular lesions in patients with persistent pain following arthroscopic femoroacetabular impingement (FAI) correction and to identify imaging findings associated with progressive cartilage damage. Methods Retrospective study evaluating patients with hip pain following arthroscopic FAI correction between 2010 and 2018. Pre- and postoperative imaging studies were analyzed independently by two blinded readers for osseous deformities (cam-deformity, hip dysplasia, acetabular overcoverage, femoral torsion) and intra-articular lesions (chondro-labral damage, capsular lesions). Prevalence of osseous deformities and intra-articular lesions was compared with paired t-tests/McNemar tests for continuous/dichotomous data. Association between imaging findings and progressive cartilage damage was assessed with logistic regression. Results Forty-six patients (mean age 29 ± 10 years; 30 female) were included. Postoperatively, 74% (34/46) of patients had any osseous deformity including 48% (22/46) acetabular and femoral deformities. Ninety-six percent (44/46) had an intra-articular lesion ranging from 20% (9/46) for femoral to 65% (30/46) for acetabular cartilage lesions. Prevalence of hip dysplasia increased (2 to 20%, p = 0.01) from pre- to postoperatively while prevalence of cam-deformity decreased (83 to 28%, p < 0.001). Progressive cartilage damage was detected in 37% (17/46) of patients and was associated with extensive preoperative cartilage damage > 2 h, i.e., > 60° (OR 7.72; p = 0.02) and an incremental increase in postoperative alpha angles (OR 1.18; p = 0.04). Conclusion Prevalence of osseous deformities secondary to over- or undercorrrection was high. Extensive preoperative cartilage damage and higher postoperative alpha angles increase the risk for progressive degeneration. Key Points • The majority of patients presented with osseous deformities of the acetabulum or femur (74%) and with intra-articular lesions (96%) on postoperative imaging. • Prevalence of hip dysplasia increased (2 to 20%, p = 0.01) from pre- to postoperatively while prevalence of a cam deformity decreased (83 to 28%, p < 0.001). • Progressive cartilage damage was present in 37% of patients and was associated with extensive preoperative cartilage damage > 2 h (OR 7.72; p = 0.02) and with an incremental increase in postoperative alpha angles (OR 1.18; p = 0.04).

PROSPECTIVE EVALUATION OF IN SITU SCREW FIXATION FOR STABLE SLIPPED CAPITAL FEMORAL EPIPHYSIS

Background: In situ screw fixation is the standard of care for the treatment of stable slipped capital femoral epiphysis (SCFE), however, recent studies recommend treatment of all slip-related cam deformity to prevent degenerative changes due to femoroacetabular impingement (FAI). Hypothesis/Purpose: The purpose of this study was to prospectively evaluate radiographic and patient reported outcomes after in situ screw fixation for stable SCFE with minimum 2-year follow-up. Methods: After obtaining IRB approval, we prospectively collected data on all consecutive stable SCFE patients who underwent in situ screw fixation at a single institution. Demographic information, Southwick slip angle (SSA) and alpha angle were recorded. The Hip disability and Osteoarthritis Outcome Score (HOOS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were collected. Basic descriptive statistics, the Mann-Whitney test, and correlation analysis was performed. Results: Forty-four hips in 38 patients with an average pre-op SSA of 41.1±20.0˚ were studied. Cohort characteristics can be found in Table 1. We observed no surgical complications of the index procedure and no cases of avascular necrosis (AVN). Twelve hips (27%) went on to have a secondary procedure (SSA range: 34˚ to 101˚) on average 2.6±2.4 years after the index surgery. These were performed to correct residual deformity, limited hip range of motion, or symptomatic impingement; one patient (2 hips) was referred for total hip arthroplasty due to significant degenerative osteoarthritis at 7.8 years follow-up. There were five complications of the secondary procedures (three implant failures and two mal-positioned implants). Our mean post-op HOOS and WOMAC scores were 84.2±16.8 and 87.8±13.9, respectively. Severe slips were 19.3 times more likely to undergo a secondary procedure than mild and moderate slips (p<0.001), however we found no correlation between slip severity and patient reported outcomes (p>0.6). Conclusion: With minimum 2-year follow-up, 27% of patients went on to require a secondary surgery after in situ screw fixation for stable SCFE. Patient reported outcomes did not correlate with slip severity (p>0.6) but were found to be significantly higher in SCFE patients that did not require a secondary procedure (p=0.023). Prophylactic treatment of all slip-related cam deformity was not found to be necessary in this prospective cohort. While in situ screw fixation can be used to safely treat mild to moderate stable slips, patients with moderate to severe stable slips may require secondary surgery and have a higher complication rate with worse patient reported outcomes. Level 2 [Table: see text]

Unusual apical femoral head deformity treated by hip arthroscopy and tunnel drilling through femoral head: a case report

Femoro-acetabular impingement (FAI), is the result of an abnormal morphology of the hip joint. On the femoral side, asphericity of the head can be highlighted by an alpha angle measurement &gt;50° on computed tomography or MRI. However, some particular cephalic asphericities can make it difficult to measure the alpha angle, leading to a diagnostic pitfall. While in the classic cam effect, the deformity is peripheral and can be treated by arthroscopic femoroplasty, an apical head deformity remains a therapeutic challenge. We present the case of a 17-year-old male patient with a femoral head deformity, corresponding to an ISHA zone 6 overhang, significantly improved in everyday and sports life by arthroscopic trapdoor technique to resect the focal central deformity while enabling concomitant treatment of central compartment pathology, in this case, a hypertrophic ligamentum teres and femoral head chondral flap. Etiology of this femoral head deformity remains uncertain but could be a particular cam deformity, sequelae to pediatric disease or instability with repeated traction of the ligament teres on the femoral head apical insertion during cephalic growth.

Evaluation of Cam Deformity on 3-Dimensional Computed Tomography With the Best-Fit Sphere Technique and the Alpha Angle Marking Method

Background: Three-dimensional computed tomography (3D-CT) is commonly used for the evaluation of cam deformity; however, it does not display the cam border directly. Purpose: To compare the efficacy of the best-fit sphere (BFS) method and the alpha angle marking (AAM) method in 3D-CT evaluation for the cam border. Study Design: Cohort study (Diagnosis); Level of evidence, 3. Methods: Twenty-six cases of cam deformity, confirmed during hip arthroscopy, were included in this study. All patients underwent a CT scan before surgery. Using multiplanar reconstruction, we obtained reformatted CT images of oblique axial, oblique coronal, and radial views. The alpha angle and femoral head-neck offset ratio (hnoR) were measured on the reformatted CT images. The cam area on 3D-CT was displayed in 4 different ways: by importing the markers from the reformatted CT images of the oblique axial view (cam-oa), the oblique coronal view (cam-oc), or the radial view (cam-r) using the AAM method, or by using the BFS method (cam-bfs). The sizes and locations of the displayed cams were compared. Results: All hips in this study had an alpha angle greater than 60° and an hnoR smaller than 0.17. The radial view measured a larger alpha angle and smaller hnoR than the oblique axial and coronal views ( P < .05). The areas of cam-oa, cam-oc, cam-r, and cam-bfs were 161.47 ± 27.96, 89.78 ± 19.23, 241.73 ± 34.55, and 329.75 ± 42.73 mm2, respectively, and their medial-to-lateral ranges along the acetabulum (clockface referents) were 12:30 to 03:00, 11:30 to 01:30, 11:30 to 03:00, and 11:00 to 03:30, respectively. Among the 4 displays, cam-bfs had the largest area and medial-to-lateral range ( P < .05), and cam-r had the second largest area and range ( P < .05). No significant difference in the mean distances from the acetabular rim to the superior border was detected among the 4 displays ( P > .05). Conclusion: The cam area displayed by the BFS method on 3D-CT was larger than those evaluated by the AAM method. In the reformatted CT, the sizes and locations of cam deformity differed among the oblique axial, oblique coronal, and radial views, with the radial view showing the greatest area.

The Prevalence of Cam Morphology: A Cross-Sectional Evaluation of 3,558 Cadaveric Femora

Purpose: We sought to determine (1) the prevalence of cam deformity in the population and that of bilateral cam deformity, (2) the typical location of a cam lesion, and (3) the typical size of a cam lesion by direct visualization in cadaveric femora.Methods: Two observers inspected 3,558 human cadaveric femora from the Hamann–Todd Osteological Collection from the Cleveland Museum of Natural History. Any asphericity &gt;2 mm from the anterior femoral neck line was classified as a cam lesion. Once lesions had been inspected, the prevalence in the population, prevalence by gender, and prevalence of bilateral deformity were determined. Additionally, each lesion was measured and localized to a specific quadrant on the femoral neck based upon location of maximal deformity.Results: Cam lesions were noted in 33% of males and 20% of females. Eighty percent of patients with a cam lesion had bilateral lesions. When stratified by location of maximal deformity, 90.9% of lesions were in the anterosuperior quadrant and 9.1% were in the anteroinferior quadrants. The average lesion measured 17 mm long × 24 mm wide × 6 mm thick in men and 14 mm × 22 mm × 4 mm in women (p &lt; 0.05).Conclusions: The population prevalence of cam deformity determined by direct visualization in cadavers may be higher than has been suggested in studies utilizing imaging modalities.Level of Evidence : Level II, diagnostic study.

Arthroscopic assessment of concomitant intraarticular pathologies in patients with osteonecrosis of the femoral head

ABSTRACT This study's purpose is to arthroscopically assess the occurrence of intraarticular pathologies in patients with osteonecrosis of the femoral head (OFNH) and to compare arthroscopic with radiologic findings. In a retrospective cohort analysis of ONFH patients undergoing combined core decompression (CD) and hip arthroscopy, concomitant intraarticular pathologies were qualitatively and quantitatively assessed by means of arthroscopy. Intraoperative findings were compared with preoperative radiodiagnostics. Descriptive statistics were performed with results displaying type, degree and prevalence of co-pathologies. Based on a cohort of 27 hips with ONFH at ARCO stages II and III, 26 (96.3%) presented with concomitant intraarticular findings. Cam-deformity (n = 22; 81.5%), labral defects (n = 23; 85.2%) and chondral defects (n = 20; 74.1%) were the most frequent. Four hips (14.8%) had foveal ligament anomalies. Intraoperative detection of cam-deformity positively correlated with radiologically assessed pathologic α angles (p = 0.09). Radiologic evaluation of the acetabular labrum distinctly differed from arthroscopic findings. Reliable statements concerning the cartilage status were not possible due to the great difference in quality of the magnetic resonance imaging (MRIs). The results of this study revealed an arthroscopically proven prevalence of co-pathologies in &gt;95% of patients with ONFH. Cam-type deformity, labral anomalies and chondral defects were the most frequent. Comparison of arthroscopic and radiologic findings showed coherent results regarding cam-deformity but revealed distinct difficulties in the assessment of the labral and chondral status emphasizing the need for standardization of preoperative radiodiagnostics. Moreover, it still has to be evaluated whether combined CD and arthroscopy can improve on the overall outcomes achieved by performance of CD only.

The hip asphericity angle: a novel angle for measurement of Cam-FAI correction

The alpha angle is routinely used for the diagnosis and quantitative description of the Cam deformity of the hip. However, a reliable identification of the femoral neck axis as its reference line can be difficult. Moreover, most cam resections include a reduction of the femoral neck diameter with an automatic posteromedial angulation of the femoral neck axis. In consequence, the reference axes for the pre- and postoperative alpha angles are different, and a comparison of both angles underlies a systematic error to relatively higher postoperative alpha angles. In order to avoid this systemic error, we propose the hip asphericity (HA) angle with a reference axis independent of the amount of bony resection. Two retrospective groups were formed, a ‘femoroacetabular impingement (FAI) group’ that had hip arthroscopy for cam resection and a ‘Control group’ without cam deformity. The alpha and HA angles were measured by three examiners. The measurements were repeated 1 month later. In the FAI group, offset correction was calculated using both angles. Statistically significant differences for both the alpha and the HA angles were found between the control and the preoperative FAI group as well as between the preoperative and postoperative FAI groups. The HA angle-correction by a mean of 27.5° was significantly higher in comparison to the alpha angle correction by a mean of 25.4°. The intertester and intratester reliability of both angles were not significantly different. The HA angle is a new and reliable radiographic parameter for measuring cam deformity and proves superior in measuring cam correction.

Femoral Head Chondrocyte Viability at the Cam Deformity in Patients With Femoroacetabular Impingement Syndrome

Background: Patients with hip pathology, such as femoroacetabular impingement (FAI) or hip dysplasia, are known to sustain chondral delamination injuries identifiable during hip arthroscopy, with an incidence of 44% to 75%. There are studies focused on understanding acetabular chondral flap viability, but there is a dearth of research regarding the viability of femoral head cartilage overlying the cam deformity in FAI. Purpose: To describe the viability and immunohistochemistry staining patterns of femoral head cartilage in the setting of FAI. Study Design: Descriptive laboratory study. Methods: Between September 2018 and August 2019, a single surgeon prospectively collected full-thickness femoral cartilage from cam deformities in 14 patients with FAI undergoing osteoplasty. Samples were assessed for viability and underwent immunohistochemistry staining for collagen type I, collagen type II, and aggrecan. Results: The data set included 14 patients. Twelve samples were assessed for viability and 14 for immunohistochemistry straining. The mean patient age was 34.1 years, and the mean body mass index was 24.69. Mean ± SD chondrocyte viability per patient was 52% ± 11%. At the time of cell isolation, 8 of the 12 patients had viability >50%, with a maximum of 68.2%. This viability increased after a primary culture period, varying from 9 to 13 days, with 10 of 12 samples having viability >90%. The viability mean after the culture period was 94.54% ± 4.89%. Harvested cartilage showed expressions of type I cartilage, type II collagen, and aggrecan in a pattern that is predictable for native cartilage. Conclusion: These data reveal that the cartilage in femoral head cartilage overlying cam deformity—much like that from acetabular chondral flaps—not only has baseline viability >50% (51.99% ± 10.83%) but the ability to increase in viability >90% after a culture period. There may be a role for use of femoral head cartilage as autograft to repair full-thickness cartilage defects of the acetabulum and femoral head, either at the time of osteochondroplasty or after a period of cell culture to improve cell viability. Clinical Relevance: A dearth of information is available regarding the viability of femoral head cartilage. This study provides insight into the cartilage viability and response to culture.

Optimal Treatment of Cam Morphology May Change the Natural History of Femoroacetabular Impingement

Background: There is debate in the literature whether cam morphology is associated with increased risk for hip osteoarthritis. The capability of femoroplasty to alter the natural history of cam morphology is still in question. Purpose: To (1) investigate the correlation between cam morphology and damage to the articular cartilage and (2) assess whether correction of the cam morphology affects survivorship of the joint, progression to arthroplasty, and functional patient-reported outcome scores. Study Design: Cohort study; Level of evidence, 3. Methods: Data were prospectively collected for patients presenting for hip arthroscopy between February 2008 and April 2017. Cases were divided into 3 groups: control group with an alpha angle <50° pre- and postoperatively, treated group with an alpha angle >55° preoperatively and <50° postoperatively, and a group with an alpha angle >55° pre- and postoperatively. All patients had minimum 2-year postoperative follow-up for the modified Harris Hip Score, the Non-arthritic Hip Score, and visual analog scale for pain. Conversion to total hip arthroplasty was recorded. Results: A 1:1:1 match successfully yielded 98 hips for each group. Follow-up time was 50.77 ± 24.60 months (mean ± SD). The pre- and postoperative mean alpha angles were 45.2°± 3.4° and 40.6°± 4.3° in the control group, respectively; 66.2°± 8.4° and 42.3°± 5.9° in the treated group; and 68.5°± 9.4° and 61.4°± 7.6° in the alpha >55° group. Intraoperatively, the alpha >55° and treated groups had greater acetabular cartilage damage than the control group ( P = .0245 and P = .0036, acetabular labrum articular disruption, respectively; P = .0347 and P = .0211, acetabular Outerbridge). The alpha >55° group achieved the patient acceptable symptomatic state for the modified Harris Hip Score (58.2%) significantly less than the treated (75.5%; P = .0100) and control (73.5%; P = .0239) groups. Progression to arthroplasty was significantly higher in the alpha >55° group (n = 17) when compared with the control (n = 8) and treated (n = 10) groups ( P = .0034 and P = .0338, respectively). Conclusion: Cam deformity was associated with higher-grade damage of the acetabular articular cartilage. An alpha angle >55° after surgery was associated with lower native hip joint survivability and less successful functional outcomes when compared with that of treated cam deformity as well as no deformity. These data suggest that correcting the cam deformity may positively affect the natural history of these patients.

Differences in articular hip cartilage gene expression between femoroacetabular impingement (FAI) and end-stage hip osteoarthritis

Objectives: The morphological deformities in Femoroacetabular Impingement (FAI) have been associated with hip osteoarthritis (OA), however the molecular mechanisms for OA initiation and progression are poorly understood. The purpose of this study was to use whole genome RNA sequencing to characterize differences in gene expression articular cartilage samples isolated from patients undergoing surgery for FAI and idiopathic OA. We hypothesized that there would be significant differences in genes expression in pathways related to inflammation as well as cartilage and bone turnover. Methods: 20 patients undergoing either hip arthroscopy for FAI (5 male, 5 female) or total hip arthroplasty (5 male, 5 female) for end-stage osteoarthritis were included in the study. FAI patients required a Cam deformity with an Alpha Angle greater than 55 while patients with dysplasia (LCEA<25) or prior hip surgery were excluded. Exclusion criteria for the THA cohort included dysplasia, and post-traumatic OA or inflammatory OA. Cartilage samples were obtained over the Cam deformity prior to femoroplasty in the FAI group or over anterosuperior femoral head-neck junction in the OA group following extraction of the femoral head. Following RNA isolation, Next Generation RNA sequencing was performed to evaluate gene expression. Differential expression data was incorporated into the Ingenuity Pathway Analysis (IPA) platform to identify differences in canonical signaling pathways associated with osteoarthritis. Results: There were 3531 genes that were significantly differentially expressed between the FAI and OA cohorts. Of these, there were 27 genes that were upregulated by a greater than 2 log-fold change in the OA cohort and 524 genes that were upregulated by a greater than 2 log-fold change in the FAI cohort. There was significant differential expression in genes related to cartilage metabolism (Table 1) and canonical osteoarthritis pathways involving BMP, TGFβ, and Wnt signaling. (Table 2). Additionally, FAI samples had significant upregulation of EGF-ERBB mediated signaling which compared to osteoarthritic tissue. Conclusion: The results of the present study support our hypothesis that there are significant differences in gene expression between FAI and OA samples in multiple pathways that are implicated in osteoarthritis. Osteoarthritis samples had increased expression of cartilage breakdown and inflammation while femoroacetabular impingement samples had greater expression of chondroprotective genes. Further study of cartilage samples from FAI patients may provide insight into the molecular mechanisms of osteoarthritis progression. [Table: see text][Table: see text]