Cam Lesion Research Articles

Imaging characteristics of hip joint microinstability: a case-control study of hip arthroscopy patients.

Hip microinstability is a clinical entity increasingly recognized and treated but challenging to diagnose with a lack of objective criteria. This study assessed the prevalence and diagnostic accuracy of different imaging findings for hip microinstability on radiograph and MR. A retrospective case-control study of 224 hips treated with arthroscopic surgery by a single orthopedic surgeon, 112 hips with clinical microinstability and 112 controls without. Pre-operative radiograph and MRI/MRA imaging were evaluated by two musculoskeletal radiologists to assess morphological parameters and imaging signs reportedly associated with hip microinstability. Four imaging features reached significance as predictors of microinstability via three-step logistic regression: labral hyperplasia and decreased lateral center edge angle on MR (OR 2.45 and 0.93, respectively) and the absence of positive ischial spine sign and absence of osteophytes on radiographs (OR 0.47 and 0.28, respectively). Increased acetabular anteversion and absence of cam lesions were more likely in the microinstability group (p = 0.02 and 0.04, respectively), but not independent predictors. Labral tears, chondral loss, abnormal ligamentum teres, anterior capsule thinning, iliocapsularis to rectus femoris ratio, posterior crescent sign, cliff sign, and femoro-epiphyseal acetabular roof (FEAR) index were not associated with microinstabillity. Imaging features may be predictive of hip microinstability in some cases. Decreased LCEA, increased acetabular anteversion, and labral hyperplasia were associated with microinstability in this study, while many other published imaging findings were not. Imaging remains complementary, but not definitive, in the diagnosis of hip microinstability.

The Alpha Angle.

➢ The alpha angle was originally defined on magnetic resonance imaging (MRI) scans, using a plane, parallel to the axis of the femoral neck. However, much of the literature on the alpha angle has used radiographs or other imaging modalities to quantify the alpha angle.➢ The measurement of the alpha angle can be unreliable, particularly on radiographs and ultrasound.➢ If radiographs are used to measure the alpha angle, the circle of best-fit method should be used on multiple different views to capture various locations of the cam lesion, and "eyeballing" or estimating the alpha angle should be avoided.➢ The cam lesion is a dynamic and 3-dimensional (3D) problem and is unlikely to be adequately defined or captured by a single angle.➢ Modern technology, including readily available 3D imaging modalities, as well as intraoperative and dynamic imaging options, provides novel, and potentially more clinically relevant, ways to quantify the alpha angle.

Outcomes of Painful Hips After Hip Arthroscopy Surgery for Femoroacetabular Impingement.

The benefits of hip arthroscopic surgery for femoroacetabular impingement are well-established. Hip arthroscopic surgery rates have risen dramatically over the last decade. Some patients, however, may continue to experience hip symptoms after surgery and are dissatisfied with their inability to return to desired optimal activity levels. The purpose of the study is to understand the long-term outcomes of patients with painful hips after hip arthroscopy for femoroacetabular impingement. This is a retrospective study of the outcomes of painful hips after hip arthroscopy for femoroacetabular impingement, with four to 14-year follow-up from 2008 to 2022. A total of 84 hip arthroscopies were performed. Most of the patients had labral tear debridement and shaving of the aspherical femoral head also known as cam lesion, and five patients had repair for labral tear. There were eight patients who had bilateral hip involvement. There were 27 men and 57 females between the second to fifth decades. The electronic patient's records and radiological images were reviewed, and patient outcomes were graded as pain-free hip (asymptomatic) or painful hip (persistent pain and symptoms of instability). After hip arthroscopy surgery, 55% (46) of hips were graded pain-free in patients who were mostly in their 20s and 30s, while 45% (38) of hips had persistent pain. These patients were in their third or fifth decade. In the painful hip cohort, 33 patients had one hip arthroscopic surgery, while five patients had multiple repeat hip arthroscopies in the same hip over a three to six-year period. Bilateral hip arthroscopies were performed at different times in eight patients of which five individuals experienced painful hip outcomes. There were seven females and one male in their 30s and 40s. The labral tear was repaired in five patients, and two patients had painful hip outcomes. Both were females in their 20s and 30s. Patients with chronic painful hips after hip arthroscopic surgery were investigated to identify the cause of the pain. If no cause was established, then they were finally referred to pain specialist clinicians for pain management. This cohort had seven patients between 28 and 43 years. Six were female and one was male. Total hip replacement (THR) was performed in four patients (4.7%). Conversely, 95.3% of patients did not need THR during the study period of 14 years. Hip arthroscopy can be an effective treatment for femoroacetabular impingement. Careful patient selection and a holistic approach are vital for a good patient outcome. The success rate of the pain-free hip after hip arthroscopy decreases with increasing age of the patient, particularly in the female gender.Patients with grade II and more degenerative chondral changes do not perform well. Patients in their fourth and fifth decade can benefit from hip arthroscopy provided a comprehensive discussion of the expected outcomes is conducted prior to surgery. Overall, hip arthroscopy remains a valuable tool, but it is important to be conscious of its limitations and potential challenges.

Comparison of Knotless Versus Knot-Tying Suture Anchors for Arthroscopic Repair of Hip Labral Tears.

Both knotless and knot-tying anchors are commonly employed in the arthroscopic repair of hip labral tears. To compare the midterm clinical results of arthroscopic hip labral repair using knot-tying versus knotless suture anchors. Cohort study; Level of evidence, 3. Patients who underwent arthroscopic hip labral repair between January 2017 and January 2021 and who had at least 2 years of follow-up were included. The patients were divided into 2 groups based on the suture anchor type: a 2.9-mm knotless suture anchor (knotless group) or a 1.8-mm knot-tying suture anchor (knot-tying group). All patients underwent femoroplasty for cam lesions and acetabular rim trimming for pincer lesions. The modified Harris Hip Score (mHHS), Hip Outcome Score-Sport-Specific Subscale (HOS-SSS), Hip Outcome Score-Activities of Daily Living (HOS-ADL), 12-item International Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain were administered both preoperatively and postoperatively. The consistency of the outcome scores was assessed using the minimal clinically important difference and Patient Acceptable Symptom State. The statistical significance between groups was evaluated using the Mann-Whitney test and quantile-based analysis of variance. A total of 413 patients were included: 256 patients in the knotless group (median age, 35 years [interquartile range, 31-38 years]; median follow-up, 34 months) and 157 patients in the knot-tying group (median age, 34 years [interquartile range, 30-38 years]; median follow-up, 25 months). There were no significant differences in postoperative mHHS, HOS-ADL, or iHOT-12 scores between the 2 groups. However, there were significant differences, favoring the knotless group over the knot-tying group, in postoperative HOS-SSS (87 ± 2 vs 86 ± 1, respectively) and VAS pain (1 vs 2, respectively) scores (P < .0001 for both). Postoperative synovitis was found in significantly more patients in the knot-tying group than in the knotless group (17 vs 5, respectively; P = .01). In this study, patients who underwent arthroscopic hip labral repair with knotless suture anchors had slightly better postoperative HOS-SSS and VAS pain scores and a lower incidence of postoperative synovitis compared with patients who underwent repair with knot-tying suture anchors.

EARLY OUTCOMES OF HIP ARTHROSCOPY FOR FEMOROACETABULAR IMPINGEMENT: A STUDY OF 7,511 CASES USING THE NAHR DATASET

This study used a national registry to assess the outcomes of hip arthroscopy (HA) for the treatment femoroacetabular impingement (FAI).All HAs for FAI recorded in the UK Non-Arthroplasty Hip Registry (NAHR) between January 2012 and September 2023 were identified. Cases were grouped according to the index procedure performed for FAI (cam, pincer, or mixed). Patient outcomes captured included the International Hip Outcome Tool (iHOT)-12.7,511 HAs were identified; 4,583 cam (61%), 675 pincer (9%), 2,253 mixed (30%). Mean age (34.8) was similar between groups. There was a greater proportion of females in the pincer group (75%) compared to cam (52%) and mixed (50%). A higher proportion of patients had a recorded cartilage injury in association with a cam lesion compared to pincer. The pincer group had poorer mean pre-op iHOT-12 scores (31.6 \[95%CI 29.9 to 33.3\]; n=364) compared to cam (33.7 \[95%CI 32.1 to 34.4\]; n=3,941) and achieved significantly lower scores at 12 months (pincer = 52.6 (50.2 to 55); n=249, cam = 58.3 (57.1 to 59.5); n=1,679).Overall, significant (p &lt; 0.0001) iHOT-12 and EQ-5D improvement vs baseline pre-operative scores were achieved for all FAI subtypes at 6 months (overall mean iHOT-12 improvement +26.0 \[95%CI 25.0 to 26.9\]; n=2,983) and maintained out to 12 months (+26.2 \[25.1 to 27.2\]; n=2,760) at which point 67% and 48% of patients continued to demonstrate a score improvement greater than or equal to the minimum clinically important difference (&gt;/=13 points) and substantial clinical benefit (&gt;/=28 points) for iHOT-12 respectively.This study demonstrates excellent early functional outcomes following HA undertaken for FAI in a large national registry.

Feasibility and potential of intraoperative ultrasound in arthroscopy of femoroacetabular impingement

ABSTRACT This study aimed to evaluate the feasibility of using ultrasound for monitoring osteochondroplasty intraoperatively, determine the factors that interfere with ultrasound imaging and assess its influence on surgeon performance. Intraoperative ultrasonography was performed during osteochondroplasty in 39 cases of arthroscopy. The femoral head–neck junction (FHNJ) was evaluated using ultrasonography. Another 39 cases, which underwent conventional arthroscopy, were included in the control group. The C-arm was used in this group at the end of osteochondroplasty to confirm that no residual cam lesion remained. Pre- and postoperative Dunn radiographs and computed tomography (CT) scans were analyzed to determine the feasibility of ultrasound. Residual cam deformity was noted in eight cases under ultrasound. The FHNJ was not detected owing to ultrasound interference by air in three cases. No difference in the α angle measured in Dunn radiographs and the residual cam deformity rate of CT at the 1:00, 2:00 or 3:00 position was found between both groups. However, the α angle at the 3:00 position was greater in the ultrasound group than in the control group (44.4 ± 4.3° versus 41.3 ± 5.1°, P &amp;lt; 0.05), suggesting that more bone was preserved at 3:00 in the ultrasound group. No difference was found in the mean operation time. None of the patients experienced complications, such as wounds or intra-articular infections. Ultrasound is a safe method for assessing FHNJ during arthroscopy. It did not change the risk of residual cam deformity but positively affected the surgeon’s performance by reducing unnecessary bone removal.

A new height contouring method for severity prediction in cam-type hip joints: 20 subject-specific cases

Cam-type femoroacetabular impingement syndrome (FAIS) is characterised by a non-spherical continuation of the femoral head into the femoral head-neck junction and is associated with damage to the acetabular cartilage. Diagnostic methods based on cam shape are progressing from 2D radiographic measurements to 3D CT measures, providing greater insight. There is currently no consensus on how to describe the 3D cam lesion shape and subject-specific impingement mechanisms are difficult to determine.A novel 3D ‘contour’ method was used to describe the proximal femur of 20 cam-type hips. Five contours, analogous to height contours on a terrain map, were used to describe the femoral head-neck junction, capturing the progressive height of the cam lesion. From that description, the cam apex (a subject's largest alpha angle), cam extent (spread around the femoral head), cam location (position around the femoral head) and average acetabular coverage, were recorded. A previously developed hip impingement model was used to apply 126 activity-based motions to each subject-specific hip shape and predict impingement occurrence and depth of incursion past the acetabular rim. Correlations between shape measures and impingement occurrence were investigated.The two contours representing the lowest heights (close to the head best fit sphere and 1 mm greater than that) generated cam alpha angle and cam extent measurements which contained the typical clinical measures (Alpha: close to best fit 47°-98°, at 1 mm 45°–77°; Extent: close to best fit 0°–129°, at 1 mm 0°–100°). The remaining contours described the progressive height of the cam lesion up to 4 mm greater than the head radius. Impingement was predicted predominantly from the first 1 mm height of the cam, with only two subjects impinging at a cam height greater than 2 mm. Therefore, it is possible that adequate resection of the first 1 mm of cam height is the most critical in reducing a subject's impingement severity.Impingement occurrence was positively correlated with the cam apex (ρ = 0.84 close to best fit, ρ = 0.70 at 1 mm height), the cam extent (ρ = 0.68 close to best fit, ρ = 0.80 at 1 mm height) and the acetabular coverage (ρ = 0.50, at 1 mm height). However, in line with other work on cam impingement, correlations between any single shape measure and the risk of impingement were not strong enough to be used with confidence as predictive tools. This supports the further development of modelling tools which sufficiently capture the complex shape and can generate an impingement risk metric which accounts for joint motion.

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

Background: In the setting of femoroacetabular impingement (FAI), decompression osteoplasties reconcile deleterious loading patterns caused by cam and pincer lesions. However, native variations of spinopelvic sagittal alignment may continue to perpetuate detrimental effects on the labrum, chondrolabral junction, and articular cartilage after hip arthroscopy. Purpose: To evaluate the effect of pelvic incidence (PI) on postoperative outcomes after hip arthroscopy for acetabular labral tears in the setting of FAI. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective query of prospectively collected data identified patients ≥18 years of age who underwent primary hip arthroscopy for FAI and acetabular labral tears between February 2014 and January 2022, with 3-, 6-, 12-, and 24-month follow-ups. Measurements for PI, pelvic tilt (PT), sacral slope (SS), and acetabular version were obtained via advanced diagnostic imaging. Patients were stratified into low-PI (<45°), moderate-PI (45°≤ PI ≤ 60°), and high-PI (>60°) cohorts. Patient-reported outcome measures (PROMs), clinically meaningful outcomes (ie, minimal clinically important difference, Patient Acceptable Symptom State, substantial clinical benefit, and maximal outcome improvement), visual analog scale (VAS) pain scores, and patient satisfaction were compared across cohorts. Results: A total of 74 patients met eligibility criteria and were stratified into low-PI (n = 28), moderate-PI (n = 31), and high-PI (n = 15) cohorts. Correspondingly, patients with high PI displayed significantly greater values for PT (P = .001), SS (P < .001), acetabular version (P < .001), and acetabular inclination (P = .049). By the 12- and 24-month follow-ups, the high-PI cohort was found to have significantly inferior PROMs, VAS pain scores, rates of clinically meaningful outcome achievement, and satisfaction relative to patients with moderate and/or low PI. No significant differences were found between cohorts regarding rates of revision arthroscopy, subsequent spine surgery, or conversion to total hip arthroplasty. Conclusion: After hip arthroscopy, patients with a high PI (>60°) exhibited inferior PROMs, rates of achieving clinically meaningful thresholds, and satisfaction at 12 and 24 months relative to patients with low or moderate PI. Conversely, the outcomes of patients with low PI (<45°) were found to match the trajectory of those with a neutral spinopelvic alignment (45°≤ PI ≤ 60°). These findings highlight the importance of analyzing spinopelvic parameters preoperatively to prognosticate outcomes before hip arthroscopy for acetabular labral tears and FAI.

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.

Cam-Type Impingement: Ensuring an Ideal Femoroplasty

When conservative measures have failed, arthroscopic femoroplasty has proven highly efficacious in treating femoroacetabular impingement (FAI) and improving hip joint mechanics. It is best to approach this in a systematic manner with preoperative planning and intraoperative confirmation. Plain radiographs, MRI and/or CT are helpful in the preoperative assessment with identifying the location and shape of the cam deformity. Understanding the extent of the cam lesion prior to surgical intervention will aid in the resection process. The resection can then be confirmed by an intra-operative fluoroscopic exam and arthroscopic dynamic motion evaluation under direct visualization. Using the trough technique, the resection can be marked using the cortical-cancellous border as a depth landmark. When performing the resection, a smooth contour should be performed, with an understanding that both over and under resection can be problematic. Adequate resection should be ensured by testing range of motion, with fluoroscopic imaging, to obtain a circumferential view of the resected area. It is essential to understand how to position the lower extremity in order to obtain different fluoroscopic views of the femoral head neck junction clock-face. Once complete, a thorough irrigation of the joint should be performed to remove bony debris. An ensuing capsular closure should be performed to minimize the risk of iatrogenic hip instability.

Association of Idiopathic Cam Morphology With Femoral and Acetabular Version: Analysis of 986 Cadaveric Hips.

Studies have correlated symptomatic femoroacetabular impingement (FAI) with femoral retroversion and cam lesions. To investigate any association between femoral and acetabular versions with cam deformity in a largely asymptomatic population. Descriptive laboratory study. A total of 986 cadaveric hips were selected from a historical osteologic collection. Each hip was assessed to determine the femoral and acetabular versions, anterior offset, and alpha angle. Cam morphology was defined as an alpha angle >60°. Multiple regression analysis was performed to determine the relationship between age, femoral version, acetabular version, and either alpha angle or anterior femoral offset. The mean alpha angle and anterior offset for the sample population were 48.1°± 10.4° and 0.77 ± 0.17 cm, respectively, with cam morphology in 149 of the 986 (15.1%) specimens. No significant difference was observed between hips with and without cam morphology with respect to the femoral (10.8°± 10° vs 10.3°± 9.6°; P = .58) or acetabular versions (17.4°± 6° vs 18.2°± 6.3°; P = .14). Multiple regression analysis did not demonstrate an association between the femoral or acetabular versions and the alpha angle, and it showed a small association between the increasing femoral and acetabular versions and a decreased anterior femoral offset (both P < .01). In a large random sample of cadaveric hips, cam morphology was not associated with femoral or acetabular retroversion. Combined with the existing literature, these findings suggest that retroversion is not associated with cam development. This study provides insight into the development of cam morphology, which may eventually aid in the evaluation and treatment of FAI.

Soft Tissue Cam Impingement in Adolescents: MRI Reveals Impingement Lesions Underappreciated on Radiographs

Background: Femoroacetabular impingement (FAI) has been described as repetitive and abnormal contact between a structurally abnormal proximal femur (cam) and/or acetabulum (pincer), occurring during the terminal range of motion of the hip. While cam and pincer lesions have traditionally been defined as osseous abnormalities, there may be a subset of adolescent patients whose impingement is primarily soft tissue (nonosseous). The existence of a nonosseous cam lesion in adolescents with FAI has not been well described. Purpose: To identify and characterize a series of adolescent patients with nonosseous (soft cam) FAI identified on magnetic resonance imaging (MRI) and compare these patients’ clinical presentation and outcome with those of a cohort with primary osseous cam FAI in the same age group. Study Design: Case series; Level of evidence, 4. Methods: A prospective institutional registry of patients with symptomatic FAI was reviewed. Patients were included if they had an MRI scan and a lateral radiograph of the hip (45° Dunn or frog) at a baseline visit. On MRI, the anterolateral femoral head was evaluated using radial, coronal, sagittal, or axial oblique sequences. A soft cam lesion was identified by the presence of soft tissue thickening of ≥2 mm at the anterolateral femoral head-neck junction. An alpha angle was measured on MRI scans and radiographs when a lesion was identified. The cohort with soft cam lesions was reviewed and findings and outcomes were compared with those of a cohort with osseous cam lesions. Continuous variables were first examined for normality, and then nonparametric tests—such as the Kruskal-Wallis test—were considered. The change between pre- and postoperative patient-reported outcomes (PROs) was described by mean and standard deviation and evaluated with an independent-samples t test. Results: A total of 31 (9.3%) of 332 hips (mean age, 16.4 years [range 13.1-19.6 years]; women, 83.9%) were identified with a soft tissue impingment lesion on MRI at the femoral head-neck junction between the 12 and 3 o'clock positions. These lesions demonstrated a thickened perichondral ring (71%), periosteal thickening (26%), or a cartilaginous epiphyseal extension (3%). The mean alpha angle on MRI was greater than on radiographs (63.5°± 7.9° vs 51.3°± 7.9°; P < .0001). A total of 22 patients (71%) with soft impingement underwent hip preservation surgery. When compared with patients in the osseous cohort who also underwent surgical management, both groups showed similar significant improvements from pre- to postoperatively (soft: modified Harris Hip Score [mHHS], 26.9 ± 18.2; Hip disability and Osteoarthritis Outcome Score [HOOS], 31.4 ± 22.9; osseous: mHHS, 22.8 ± 20.8; HOOS, 27.4 ± 20.1; P < .0001), with a mean follow-up of 3.4 years (range, 1-7 years) in the soft cam cohort and 3 years (1-10.1 years) in the osseous cam cohort. Conclusion: Clinicians should be aware of nonosseous or soft cam lesions that cause impingement in adolescent patients without an obvious osseous cam on radiographs. MRI is required to detect these soft cam lesions. When nonoperative treatment fails, the PROs in these patients after operative management are comparable with those in patients with osseous cam lesions. Further research is needed to determine whether the soft cam precedes an osseous cam or whether it is a separate entity.

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.

Effect of cam resection depth on clinical outcomes after primary hip arthroscopy.

The amount of resection or the starting point of the resection on the femoral head for cam lesions in femoroacetabular impingement (FAI) is controversial. The purpose of this study was to study the effect of postoperative resection depth, and resection arc ratio of cam lesion on the frequency of achieving substantial clinical benefit (SCB), patient acceptable state (PASS) in modified Harris Hip Score (mHHS) and Hip Outcome Score Activity of Daily Living (HOSADL), 2 years postoperatively. All patients who underwent first-time hip arthroscopy for FAI with a 2-year follow-up were included in this study. Patient-reported outcomes included the mHHS, HOSADL, and visual analogue scale for pain (Pain VAS). Radiological parameters such as alpha angletraditional (αT), alpha anglecartilage (αC), resection arc ratio (% alpha anglecartilage-alpha angletraditional/360°), resection depth (''D''mm) and resection depth ratio 'D%' (D/femoral head diameter %) were measured using the 45° Dunn view. We identified 26 patients (27 hips) with 2-year follow-up. There were 10 female and 16 male patients. The mean age of the patients was 33 ± 12 years.Higher frequency of achieving SCB threshold for mHHS was related to labrum repair (73% vs. debridement '27%' p = 0.03), lower preoperative αT (64° vs. 76°, p = 0.04), lower preoperative mHHS (54 vs. 81, p < 0.001) and higher preoperative VAS scores (8 vs. 7, p = 0.02). Higher frequency of reaching PASS threshold for mHHS was associated with lower αC (82°vs. 92° p:0.02), lower RA (8% vs. 11%, p = 0.03), lower D (2.8 mm vs. 4.5 mm p:0.03), lower D% (4.7% vs. 8.4% p = 0.04) and higher postoperative mHHS (97 vs. 82 p < 0.001). A higher frequency of achieving SCB for HOSADL was related to lower D% (5% vs. 10.5%, p = 0.04).Cam resection depth affects the frequency of achieving clinically meaningful scores and resection depth less than 6% of the femoral head diameter seems to be appropriate for optimal results. The starting point of resection on head cartilage needs to be <90° when alpha angle is used for reference.

A Superolateral Cam Lesion Location Increases Odds of Total Hip Arthroplasty 5 Years After Hip Arthroscopy

To determine if radiographic cam location is associated with hip survivorship and postoperative patient-reported outcomes (PROs) at 5-year follow-up. We conducted a review of prospectively collected data of patients with cam lesions who underwent hip arthroscopy for femoroacetabular impingement syndrome. Cam lesions were categorized into 3 locations: superolateral, anterolateral, or anterior. Conversion to total hip arthroplasty (THA), revision rates, and reoperation rates were assessed. Patient-reported outcome measures, including modified Harris Hip Scores (mHHS) and Non-Arthritic Hip Scores (NAHS), were collected preoperatively and at 5-year follow-up. Of the 156-patients, 125 met the final criteria (80.1%). Mean age was 41.1 ± 12.7 years. Seventy-one patients (56.8%) had superolateral cam lesions, 41 (32.8%) had anterolateral lesions, and 13 (10.4%) had anterior lesions. Revision rates within 5 years were 7.7% for anterior, 24.4% for anterolateral, and 14.1% for superolateral lesions; conversions to THAs were 15.4% for anterior), 7.3% for anterolateral, and 8.5% for superolateral. Reoperations were 23.1% for anterior, 29.3% for anterolateral, and 21.1% for superolateral. The superolateral cohort was younger than the anterior and anterolateral cohorts (anterior, 46.6 ± 12.2 years; anterolateral, 44.7 ± 12.2 years; superolateral, 38.1 ± 12.3 years; P= .006). Multivariable analysis showed the anterolateral group was significantly predictive of lower odds of undergoing THA compared to the superolateral group (odds ratio, 0.01; 95% CI, <0.01-0.72; P= .03). There were no differences in the 5-year improvement in mHHS (anterior, 32.4; anterolateral, 36.8; superolateral, 33.0; P= .29) or NAHS (anterior, 34.8; anterolateral, 39.0; superolateral, 37.3; P= .65). A superolateral cam lesion increases the odds of conversion to THA within 5 years of hip arthroscopy compared to those with anterolateral lesions on multivariable analysis. Those with superolateral lesions were significantly younger compared to those with anterior or anterolateral lesions. Cam lesion location did not affect improvement in PROs at 5-year follow-up. Level III, retrospective comparative prognostic trial.

Poster 114: Viability and Expression of Chondrocytes Harvested During Arthroscopic Treatment of Femoroacetabular Impingement

Poster 114: Viability and Expression of Chondrocytes Harvested During Arthroscopic Treatment of Femoroacetabular Impingement

Poster 232: Clinical Outcomes Among Individuals with Global Acetabular Retroversion who Underwent Hip Arthroscopy for FAI with Minimum 5-Year Follow-Up

Objectives: The purpose of this study was to compare functional outcomes and clinical threshold achievement rates of patients with radiographic signs of global acetabular retroversion who underwent hip arthroscopy for FAI with minimum follow-up of 5 years. Methods: Patients were identified from a single-surgeon prospectively-collected database who underwent primary hip arthroscopy for treatment of FAI. Patients completed patient-reported outcome (PRO) surveys at both baseline and at 5-year follow-up. Demographic data was collected including age, sex, BMI at time of surgery, and patient-reported symptom length. Intraoperative findings were recorded, including the Outerbridge grade, presence of labral tears, chondral delamination, subspine impingement, cam lesions, pincer lesions, and mixed-type FAI. Global acetabular retroversion was assessed on AP view using three radiographic signs: ischial spine, posterior wall, and crossover signs. Other radiographic measures included alpha angle measured on three view (AP, 45° Dunn, 90° Dunn), lateral center edge angle (LCEA), and Tönnis grade. Results: We identified 124 primary hip arthroscopy patients who had minimum 5-year follow-up with adequate imaging and complete 5-year PROs. Preoperative X-rays demonstrated presence of ischial spine sign in 65 patients (52.4%), posterior wall sign in 61 patients (49.2%), and crossover sign in 75 patients (60.5%). Mean alpha angle was highest on AP view (62.2°), followed by 45° Dunn view (55.9°) and 90° Dunn view (50.9°) and mean LCEA was 38.5°. A baseline comparison demonstrated no significant differences between groups in age, sex, BMI, preoperative symptom length, Tönnis grade, Outerbridge grade, and preoperative mHHS or NAHS (p&gt;0.05). At 5-year follow-up, patients reported significant improvement in both mHHS (mean 50.4 to 82.7, p&lt;0.001) and NAHS (49.4 to 85.5, p&lt;0.001). Achievement rates were high for MCID (90.3%), SCB (80.7%), and PASS (79.0%) for the mHHS. Three-way frequency comparison of acetabular retroversion signs found that all three signs tended to be present together (40 patients, 32.3%) or absent together (31 patients, 25.0%). Pairwise comparisons with tetrachoric correlation testing found all three signs to be significantly correlated with one another: ischial spine sign versus posterior wall (rtet=0.65, corrected p&lt;0.001), ischial spine sign versus crossover sign (rtet=0.74, corrected p&lt;0.001), and posterior wall sign versus crossover sign (rtet=0.51, corrected p&lt;0.001). Multivariable analysis did not find any of the three signs to be significant independent predictors of 5-year improvement in mHHS or NAHS (p&gt;0.05). Posterior wall sign was associated with lower odds of achieving the MCID (OR = 0.62, 95% CI [0.06 to 1.09]) but this did not achieve significance (χ2=3.39, p=0.07). Overall, achievement rates for MCID, SCB, and PASS did not significantly differ between the cohorts with respect to each sign (p&gt;0.05). Conclusions: Clinical outcomes and achievement rates at 5-year follow-up demonstrated no significant differences among patients with respect to each sign of acetabular retroversion based on mHHS, NAHS, MCID, SCB and PASS. Surgeons should be reassured that these patients regain function at a rate similar to the greater FAI population.

Poster 119: MRI evidence of labral tears in healthy young athletes without hip pain

Objectives: The prevalence of labral tears in asymptomatic active adults has been reported, but the prevalence of labral tears and other incidental hip lesions in the asymptomatic adolescent population has not yet been determined. The purpose of this study was to determine the prevalence of hip abnormalities detected on 3T MRI in an active adolescent population with no hip symptoms and, secondarily to compare with hip abnormalities found in adolescents who underwent an MRI for a hip related condition. Methods: Following IRB approval, adolescent patients presenting with isolated knee pain requiring knee MRI were prospectively recruited to have a 3T MRI of their asymptomatic contralateral hip (ASx). A comparison group of adolescent subjects who underwent an MRI for hip pain was enrolled retrospectively (Sx). All MRI scans were anonymized and randomized. Based on preliminary power analysis, 50 subjects were enrolled for each cohort. Blinded to the patient’s cohort status, clinical and demographic data, 2 fellowship-trained musculoskeletal radiologists evaluated these MRI’s independently for abnormal hip lesions, including labral tears. Inter-reader reliability was evaluated using Cohen’s Kappa. A chi-square or Fisher’s exact test was used to compare the prevalence of these hip lesions between the two cohorts. Results: Average patient age was 14.9 years for both cohorts (range 9-18 years); 52% were female. In the ASx group, incidental labral tears were found in 18%, labral/paralabral cysts 6%, cartilage lesion 0%, subchondral cyst 0%, ligamentum teres tear 0%, femoral fibrocystic change 0%, cam lesion 30%, acetabular bone edema 0%, acetabular rim fracture 0%. The prevalence of labral tears (30%, P-value 0.160) and cam lesion (36%, P-value 0.523) in the Sx group was not significantly different from that of the ASx cohort. Conclusions: Labral tears were present on 3T MRI’s of adolescents with and without hip pain. While MRI is essential to confirm the surgeon’s suspicion and to detect unexpected pathology, clinical exam and history are crucial in pinpointing clinically relevant abnormal imaging findings. [Table: see text]

Poster 214: The Effect of Femoral Retroversion on Hip Range of Motion – A 3D Computational Analysis

Objectives: A subset of patients undergoing hip arthroscopy suffers from persistent pain and dysfunction which can be secondary to a number of factors. Femoral rotational deformities are often overlooked and/or providers are unsure when to address femoral deformities. Currently, there is limited to no data guiding surgeons when to consider a femoral osteotomy at the time of hip arthroscopy for FAI. Through previously validated computer-assisted 3D modeling software, this study sought to answer two questions: 1) How much femoral retroversion is too much to render cam femoroplasty ineffective in improving range of motion (ROM)? 2) In the setting of an osteotomy, what degree of femoral version correction would be sufficient to improve impingement free ROM? Methods: Ten patients were selected with symptomatic focal cam impingement lesions who underwent hip arthroscopy and had pre- and post-operative computed tomography (CT) scans. These patients were screened for normal acetabular morphology and demonstrated no radiographic signs of osteoarthritis. Pre- and post-operative 3D modeling of the involved hip was performed and subsequently dynamized with the femoral version set at (15, 5, -5 and -15 degrees) to define the impingement free ROM and location of impingement with maximum hip flexion and maximum hip internal rotation (IR) at 90 degrees of hip flexion. Results: Mean alpha angle pre and post cam resection were 66°±7.6 ° and 44°±4.9° respectively and were significantly different (p=0.003). Location of impingement shifted during hip flexion from the medial to anterior femoral neck with decreasing femoral version while the IR impingement location remained on the anterior femoral neck and was unaffected by femoral version. Kruskal-Wallis testing demonstrated decreasing femoral version significantly decreased hip flexion and IR ROM in both the pre and post cam resection groups (p&lt;0.0003). Impingement free ROM, as defined by hip flexion and IR greater than 90° and 10° respectively, was only identified in the 5 and 15 degree femoral anteversion models irrespective of whether cam femoroplasty had been performed. In the post cam resection group, hip IR ROM was significantly less with any level of decreasing femoral version (p&lt;0.002) while hip flexion ROM was significantly less with any level of decreased femoral version when compared to 15 degrees of anteversion (p&lt;0.04). When assessing the degree of change in ROM between the pre and post cam resection groups, femoral version had contrasting effects on hip ROM with decreasing femoral version showing less improvement with hip IR ROM while the femoral retroversion models had significantly greater improvements in hip flexion ROM when compared to the 15 degree anteversion model (p=0.02). Conclusions: Decreasing femoral version demonstrates significantly decreased hip flexion and IR both in the presence and absence of a CAM lesion. After cam femoroplasty, any level of decreased femoral version has a significant effect on hip ROM when compared to normal femoral anteversion. Femoral version seems to be the predominant factor in determining the amount of hip IR ROM in flexion and to a certain extent hip flexion ROM irrespective of the cam FAI. Impingement free ROM was only identified within the femoral anteversion models even after cam femoroplasty suggesting that recurrent mechanical collision and intra-articular damage seen with FAI may still be present with any level of true femoral retroversion. This study provides insight into the changes in hip flexion and IR that can be expected following both cam resection and simulated femoral osteotomy. [Table: see text]

Can a Computational Model Predict the Effect of Lesion Location on Cam-type Hip Impingement?

The Warwick consensus defined femoroacetabular impingement syndrome as a motion-related clinical disorder of the hip with a triad of symptoms, clinical signs, and imaging findings representing symptomatic premature contact between the proximal femur and acetabulum. Several factors appear to cause labral and cartilage damage, including joint shape and orientation and patient activities. There is a lack of tools to predict impingement patterns in a patient across activities. Current computational modeling tools either measure pure ROM of the joint or include complexity that reduces reliability and increases time to achieve a solution. The purpose of this study was to examine the efficacy of a low computational cost approach to combining cam-type hip shape and multiple hip motions for predicting impingement. Specifically, we sought to determine (1) the potential to distinguish impingement in individual hip shapes by analyzing the difference between a cam lesion at the anterior femoral neck and one located at the superior femoral neck; (2) sensitivity to three aspects of hip alignment, namely femoral neck-shaft angle, femoral version angle, and pelvic tilt; and (3) the difference in impingement measures between the individual activities in our hip motion dataset. A model of the shape and alignment of a cam-type impinging hip was created and used to describe two locations of a cam lesion on the femoral head-neck junction (superior and anterior) based on joint shape information available in prior studies. Sensitivity to hip alignment was assessed by varying three aspects from a baseline (typical alignment described in prior studies), namely, femoral neck-shaft angle, femoral version, and pelvic tilt. Hip movements were selected from an existing database of 18 volunteers performing 13 activities (10 male, eight female; mean age 44 ± 19 years). A subset was selected to maximize variation in the range of joint angles and maintain a consistent number of people performing each activity, which resulted in nine people per activity, including at least three of each sex. Activities included pivoting during walking, squatting, and golf swing. All selected hip motion cases were applied to each hip shape model. For the first part of the study, the number of motion cases in which impingement was predicted was recorded. Quantitative analyses of the depth of penetration of the cam lesion into the acetabular socket and qualitative observations of impingement location were made for each lesion location (anterior and superior). In the second part of the study, in which we aimed to test the sensitivity of the findings to hip joint orientation, full analysis of both cam lesion locations was repeated for three modified joint orientations. Finally, the results from the first part of the analysis were divided by activity to understand how the composition of the activity dataset affected the results. The two locations of cam lesion generated impingement in a different percentage of motion cases (anterior cam: 56% of motion cases; superior cam: 13% of motion cases) and different areas of impingement in the acetabulum, but there were qualitatively similar penetration depths (anterior cam: 6.8° ± 5.4°; superior cam: 7.9° ± 5.8°). The most substantial effects of changing the joint orientation were a lower femoral version angle for the anterior cam, which increased the percentage of motion cases generating impingement to 67%, and lower neck-shaft angle for the superior cam, which increased the percentage of motion cases generating impingement to 37%. Flexion-dominated activities (for example, squatting) only generated impingement with the anterior cam. The superior cam generated impingement during activities with high internal-external rotation of the joint (for example, the golf swing). This work demonstrated the capability of a simple, rapid computational tool to assess impingement of a specific cam-type hip shape (under 5 minutes for more than 100 motion cases). To our knowledge, this study is the first to do so for a large set of motion cases representing a range of activities affecting the hip, and could be used in planning surgical bone removal. The results of this study imply that patients with femoroacetabular impingement syndrome with cam lesions on the superior femoral head-neck junction may experience impinging during motions that are not strongly represented by current physical diagnostic tests. The use of this tool for surgical planning will require streamlined patient-specific hip shape extraction from imaging, model sensitivity testing, evaluation of the hip activity database, and validation of impingement predictions at an individual patient level.