The Principles of Hip Joint Preservation.

The 3 primary factors involved with preservation of the hip joint are femoroacetabular impingement (FAI), hip dysplasia, and femoral torsion abnormalities. Each of these factors affects the health of the acetabular labrum and femoroacetabular cartilage. The appropriate surgical treatments for each of these factors include arthroscopic or open femoroplasty or acetabuloplasty for FAI, periacetabular osteotomy (PAO) for acetabular dysplasia, and de-rotational femoral osteotomy for femoral torsion abnormalities. When evaluating patients with prearthritic hip conditions, orthopaedic surgeons should be aware of the various factors involved in hip joint preservation and, if surgery is indicated, surgeons should be sure to address all factors that need surgical treatment rather than focusing on the most obvious issue or injury (e.g., a labral tear). The purpose of this infographic is to illustrate the importance of the factors involved in hip joint preservation and the appropriate treatments for pathology in any of these factors.

During Postless Hip Arthroscopy, Male Patients, High Body Mass Index, Low Beighton Scores, and Limited Range of Motion Require High Traction Force.

PURPOSE: To determine the effects of demographic and anatomic factors on traction force required during postless hip arthroscopy. METHODS: A prospectively collected database was retrospectively analyzed on patients undergoing hip arthroscopy by the senior author, including patient sex, age, body mass index (BMI), Beighton Hypermobility Score, hip range of motion in clinic and under anesthesia, hip dysplasia, acetabular version, and femoral version. All patients underwent postless hip arthroscopy under general anesthesia. At the initiation of hip arthroscopy, the traction force required to distract the hip joint was measured before and following interportal capsulotomy. Multiple regression analysis was performed to determine the effects of demographic and anatomic factors on measured distraction force. RESULTS: In total, 352 hips (114 male, 238 female) were included with a mean age of 32.6 years and a mean BMI of 24.1 kg/m2. Mean initial traction force was 109 lbs and decreased to 94.3 lbs following capsulotomy (P < .0001). The starting traction force was significantly greater in male patients (P < .001), patients with a lack of hypermobility (Beighton Hypermobility Score of 0-2) (P = .026), and in patients with lower abduction (P < .001), lower internal rotation (P = .002), and lower external rotation (P = .012) on multiple regression analysis. When performing a subanalysis divided by sex, male patients with elevated BMI required significantly greater starting traction force (P = .014). Lateral center edge angle, sourcil angle, and the presence of hip dysplasia did not demonstrate a significant correlation with traction force. CONCLUSIONS: Male patients, patients with reduced preoperative hip range of motion, patients with a lack of joint hypermobility, and male patients with an elevated BMI require greater initial traction force during postless hip arthroscopy. LEVEL OF EVIDENCE: Level IV, retrospective case series.

The Windshield Wiper Sign Is an Instability-Related Osteochondral Defect of the Anterolateral Femoral Head.

PURPOSE: To investigate a radiographic sign believed to be indicative of hip instability and acetabular suction seal disruption in the native hip, coined the "windshield wiper" (WSW) sign. METHODS: A retrospective review was performed for patients who underwent periacetabular osteotomy (PAO) with the senior author between March 2021 and September 2023. A WSW sign was identified on plain films as a concave or flat osteochondral defect on the anterolateral femoral head extending medial to the head-neck junction with resultant loss of femoral head sphericity in the native hip. Every patient underwent a standardized series of radiographs, as well as computed tomography and magnetic resonance imaging. All patients underwent arthroscopy before PAO to address intra-articular pathology and other indicated procedures. The osteochondral defect and resultant suction seal disruption were verified during arthroscopy. These patients were then compared with a control group of arthroscopically treated hips without hip instability. RESULTS: Of 250 patients reviewed, a total of 19 hips in 17 patients (prevalence of 7.6%) demonstrated radiographic evidence of the WSW sign. All patients with a WSW sign presented with symptomatic clinical hip instability requiring a PAO. The mean patient age was 31.2 years, with a mean lateral center-edge angle (LCEA) of 14.3°. There were 13 hips (68.4%) with dysplasia, 4 (21.1%) with borderline dysplasia, and 2 (10.5%) with a normal LCEA. All patients with a WSW sign and LCEA ≥ 20° displayed significant femoral antetorsion abnormalities. All arthroscopic videos and images demonstrated a compromised suction seal. Of the 50 control group hips reviewed, the WSW sign was not identified. CONCLUSIONS: The WSW sign is an uncommon radiographic finding in patients with hip instability. When identified, it can be predictive of substantial instability, especially in cases which are otherwise considered borderline dysplasia or normal based on LCEA. LEVEL OF EVIDENCE: Level III, retrospective comparative case control study.

Patients Undergoing Postless Hip Arthroscopy Demonstrate Significantly Better Patient-Reported Outcomes and Clinically Significant Outcomes Compared to Conventional Post-Assisted Hip Arthroscopy at Short-Term Follow-Up.

PURPOSE: To prospectively compare the short-term clinical outcomes of patients undergoing hip arthroscopy with versus without the use of a perineal post. METHODS: A prospective, single-surgeon cohort study was performed on a subset of patients undergoing hip arthroscopy between 2020 and 2022. A post-free hip distraction system was used at 1 center at which the senior author operates, and a perineal post was used at another surgical location. An electronic survey of patient-reported outcome measures (PROMs) was completed by each patient at a minimum of 1 year postoperatively. PROMs included a visual analog scale for pain; University of California, Los Angeles (UCLA) Activity Scale; modified Harris Hip Score (mHHS); Hip Outcome Score-Sports-Specific Subscale (HOS-SSS); and a Single Assessment Numeric Evaluation. Postoperative scores and clinically significant outcomes, including the minimal clinically important difference, substantial clinical benefit, and patient acceptable symptom state, for each PROM were compared between groups. RESULTS: Sixty-nine patients were reached for follow-up (41 post, 28 postless) of 87 patients eligible for the study (79%). No significant differences were found between groups in terms of sex (post: 61% female, postless: 54% female, P = .54), age (post: 34 years, postless: 29 years, P = .11), body mass index (post: 26, postless: 24, P = .23), or follow-up duration (post: 24.4 months, postless: 21.3 months, P = .16). There was a significantly higher visual analog scale (3.1 vs 1.4, P = .01), a significantly lower UCLA Activity Scale score (7.0 vs 8.4, P = .02), and a significantly lower mHHS (73.7 vs 82.2, P = .03) in the post-assisted group. A significantly higher proportion of patients in the postless group achieved a patient acceptable symptom state for the UCLA (89.3% vs 68.3%, P = .04), mHHS (84.6% vs 61.0%, P = .04), and HOS-SSS (84.0% vs 61.0%, P = .048) and a substantial clinical benefit for HOS-SSS (72.0% vs 41.5%, P = .02). One patient (2.6%) in the post group underwent revision hip arthroscopy, and another was indicated for total hip arthroplasty by the time of follow-up. CONCLUSIONS: Postless hip arthroscopy may result in better clinical outcomes compared with post-assisted hip arthroscopy. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

The Everted Acetabular Labrum: Patho-anatomy, Magnetic Resonance Imaging and Arthroscopic Findings of a Native Variant.

PURPOSE: The purpose of this study was to introduce a native labral variant, the everted acetabular labrum, and to describe the patho-anatomy, magnetic resonance imaging and magnetic resonance arthrogram (MRI/MRA) characteristics and the arthroscopic findings in this condition. METHODS: All primary hip arthroscopy procedures performed by the senior author between June 2013 and January 2020 were reviewed retrospectively. An everted acetabular labrum was identified as a segment of labrum that lacked apposition to the femoral head with the hip off traction. All everted labra were treated with labral advancement and repair with or without augmentation or reconstruction. The labrum-to-femoral head distance was measured in 3T MRI/MRA at the 1-2 o'clock position. A random selection of 38 hips without an everted labrum served as controls to compare radiographic parameters. RESULTS: A total of 68 hips were identified as having an everted labrum during the study period (mean age, 29.1 years), and 55 hips had advanced imaging available for review. MRI/MRA scans revealed the everted labrum to have a triangular shape in 17 hips (31%) and a blunted/round shape in 38 hips (69%), which differed significantly from controls (triangular 25/38 [66%], blunted 13/38 [34%], P < 0.001). The average labrum-to-femoral head distance was 1.4 mm for everted labra versus 0.0 mm for controls (P < 0.0001) and the mean labral lengths and widths were significantly shorter than those of controls (both P < 0.01). Of the hips, 8 underwent labral reconstruction or augmentation, and 61 underwent labral advancement/repair. CONCLUSION: The everted acetabular labrum is a native variant that is identifiable during hip arthroscopy by assessing the labral seal off traction. Preoperative MRI/MRA findings can be highly predictive of an everted labrum. Surgical treatment includes labral advancement and repair or reconstruction to restore contact between the labrum and the femoral head. LEVEL OF EVIDENCE: III, retrospective comparative study.

Post-Related Complications in Hip Arthroscopy Are Reported Significantly Greater in Prospective Versus Retrospective Literature: A Systematic Review.

PURPOSE: To determine whether there are differences in (1) the incidence of post-related complications following hip arthroscopy between prospective and retrospective publications; and (2) between post-assisted and postless techniques. METHODS: A systematic review was performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to characterize post-related complications following hip arthroscopy for central or peripheral compartment hip pathology, including femoroacetabular impingement syndrome and chondrolabral injury. Inclusion criteria were prospective and retrospective Level I-IV evidence investigations that reported results of hip arthroscopy performed in the supine position. Exclusion criteria included open or extra-articular endoscopic hip surgery. Post-related complications included pudendal nerve injury (sexual dysfunction, dyspareunia, perineal pain or numbness) or perineum/external genitalia soft-tissue injury. RESULTS: Ninety-four studies (12,212 hips; 49% male, 51% female; 52% Level IV evidence) were analyzed. Prospective studies (3,032 hips) report a greater incidence of post-related complications compared with retrospective (8,116 hips) studies (7.1% vs 1.4%, P < .001). Three studies (1,064 hips) used a postless technique and all reported a 0% incidence of pudendal neurapraxia or perineal soft tissue injury. Most pudendal nerve complications were transient, resolving by 3 months, but permanent nerve injury was reported in 4 cases. Only 19%, 22%, 7%, and 4% of studies reported a total surgery time, traction time, traction force, and bed Trendelenburg angle for their study samples, respectively. CONCLUSIONS: The incidence of post-related complications is 5 times greater in prospective (versus retrospective) hip arthroscopy literature. Postless distraction resulted in a 0% incidence of post-related injuries. LEVEL OF EVIDENCE: IV, systematic review of Level I-IV evidence.

Platelet-Rich Plasma Versus Hyaluronic Acid for Hip Osteoarthritis Yields Similarly Beneficial Short-Term Clinical Outcomes: A Systematic Review and Meta-analysis of Level I and II Randomized Controlled Trials.

PURPOSE: To systematically review the literature to compare the efficacy of platelet-rich plasma (PRP) and hyaluronic acid (HA) injections for the treatment of hip osteoarthritis (OA). METHODS: A systematic review was performed by searching PubMed, the Cochrane Library, and Embase to identify randomized controlled trials that compared the clinical efficacy of PRP and HA injections for hip OA. The search phrase used was hip, osteoarthritis, platelet-rich plasma, hyaluronic acid, randomized. Patients were assessed based on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Visual Analog Scale (VAS) for pain, and the Harris Hip Score (HHS). Subanalyses were performed for any outcome score in which ≥3 studies reported results. RESULTS: Six studies (5 level I, 1 level II) met inclusion criteria, including 211 patients undergoing intra-articular injection with PRP (mean age 60.0 years, mean follow-up 12.2 months) and 197 patients with HA (mean age 62.3 years, mean follow-up 11.9 months). No significant differences were found in the weighted improvement of any outcome score (WOMAC, VAS, or HHS) from preinjection to postinjection between groups. When excluding a study with the highest risk of bias to eliminate heterogeneity, pooled subanalysis demonstrated no significant differences in WOMAC subscores between PRP and HA groups. Similarly, in a pooled subanalysis that isolated patients treated with leukocyte-poor PRP, no significant differences in WOMAC subscores were found between PRP and HA groups. CONCLUSION: Patients undergoing treatment for hip OA with either PRP or HA injections can expect to experience similarly beneficial short-term clinical outcomes. LEVEL OF EVIDENCE: II, systematic review of level I and II studies.

Criteria for the Operating Room Confirmation of the Diagnosis of Hip Instability: The Results of an International Expert Consensus Conference.

PURPOSE: The purpose of this study was to establish an international expert consensus on operating room findings that aid in the diagnosis of hip instability. METHODS: An expert panel was convened to build an international consensus on the operating room diagnosis/confirmation of hip instability. Seventeen surgeons who have published or lectured nationally or internationally on the topic of hip instability were invited to participate. Fifteen panel members completed a pre-meeting questionnaire and agreed to participate in a 1-day consensus meeting on May 15, 2021. A review of the literature was performed to identify published intraoperative reference criteria used in the diagnosis of hip instability. Studies were included for discussion if they reported and intraoperative findings associated with hip instability. The evidence for and against each criteria was discussed, followed by an anonymous voting process. For consensus, defined a priori, items were included in the final criteria set if at least 80% of experts agreed. RESULTS: A review of the published literature identified 11 operating room criteria that have been used to facilitate the diagnosis of hip instability. Six additional criteria were proposed by panel members as part of the pre-meeting questionnaire. Consensus agreement was achieved for 8 criteria, namely ease of hip distraction under anesthesia (100.0% agreement), inside-out pattern of chondral damage (100.0% agreement), location of chondral damage on the acetabulum (93.3% agreement), pattern of labral damage (93.3% agreement), anteroinferior labrum chondral damage (86.7% agreement), perifoveal cartilage damage (97.6% agreement), a capsular defect (86.7% agreement), and capsular status (80.0% agreement). Consensus was not achieved for 9 items, namely ligamentum teres tear (66.7% agreement), arthroscopic stability tests (46.7% agreement), persistent distraction after removal of traction (46.7% agreement), findings of examination under anesthesia (46.7% agreement), the femoral head divot sign (40.0% agreement), inferomedial synovitis (26.7% agreement), drive-through sign (26.7% agreement), iliopsoas irritation (26.7% agreement) and ligamentum teres-labral kissing lesion (13.3% agreement). All experts agreed on the final list of 8 criteria items reaching consensus. CONCLUSION: This expert panel identified 8 criteria that can be used in the operating room to help confirm the diagnosis of hip instability. LEVEL OF EVIDENCE: Level V expert opinion.

A Systematic Review Shows High Variation in Terminology, Surgical Techniques, Preoperative Diagnostic Measures, and Geographic Differences in the Treatment of Athletic Pubalgia/Sports Hernia/Core Muscle Injury/Inguinal Disruption.

PURPOSE: To perform a systematic review of reported terminologies, surgical techniques, preoperative diagnostic measures, and geographic differences in the treatment of core muscle injury (CMI)/athletic pubalgia/inguinal disruption. METHODS: A systematic review was performed by searching PubMed, the Cochrane Library, and Embase to identify clinical studies or articles that described a surgical technique to treat CMI refractory to nonoperative treatment. The search phrase used was "core muscle injury" OR "sports hernia" OR "athletic pubalgia" OR "inguinal disruption." The diagnostic terminology, country of publication, preoperative diagnostic measures, surgical technique, and subspecialty of the operating surgeons described in each article were extracted and reported. RESULTS: Thirty-one studies met the inclusion and exclusion criteria, including 3 surgical technique articles and 28 clinical articles (2 Level I evidence, 1 Level II, 4 Level III, and 21 Level IV). A total of 1,571 patients were included. The most common terminology used to describe the diagnosis was "athletic pubalgia," followed by "sports hernia." Plain radiographs and magnetic resonance imaging of the pelvis were the most common imaging modalities used in the preoperative evaluation of CMI/athletic pubalgia/inguinal disruption. Tenderness-to-palpation testing was the most common technique performed during physical examination, although the specific locations assessed with this technique varied substantially. The operating surgeons were general surgeons (16 articles), a combination of orthopaedic and general surgeons (7 articles), or orthopaedic surgeons (5 articles). The most common procedures performed were open or laparoscopic mesh repair, adductor tenotomy, primary tissue (hernia) repair, and rectus abdominis repair. The procedures performed differed on the basis of surgeon subspecialty, geographic location, and year of publication. CONCLUSIONS: A variety of diagnostic methods and surgical procedures have been used in the treatment of a CMI/athletic pubalgia/sports hernia/inguinal disruption. These procedures are performed by orthopaedic and/or general surgeons, with the procedures performed differing on the basis of surgeon subspecialty and geographic location. LEVEL OF EVIDENCE: Level V, systematic review of Level I to V studies.

Editorial Commentary: Treating Hip Impingement Without a Computed Tomography Scan? You Might as Well Operate With a Blindfold.

Hip impingement is defined as a bony conflict between the femur and acetabulum occurring throughout normal or supraphysiological range of motion. Traditionally, the cause was attributed to reduced femoral head-neck offset and/or excessive acetabular coverage, giving rise to cam, pincer, and mixed impingement. However, recent outcome studies showing less favorable results of hip arthroscopy in patients with femoral and acetabular version abnormalities have sparked renewed interest in the pathomechanics of hip impingement. We now have a greater appreciation for the 3-dimensional scope of the problem through specialized computed tomography sequencing allowing assessment of the entire limb and pelvis. Consequently, we have learned that rotational hip range of motion is more strongly correlated with combined femoral and acetabular version than with the sphericity of the femoral head, allowing us to counsel patients accordingly. We also recognize that impingement can occur with little to no femoral asphericity if the combined femoral and acetabular version does not permit adequate clearance for unimpeded motion. This improved understanding can be applied to diagnose subtle and uncommon cases of impingement and will ultimately enable a more complete bony resection.

Returning to Climb after Epiphyseal Finger Stress Fracture.

The number of youth participating in rock climbing has increased over the years. Finger stress epiphyseal fractures are the most common injury among youth climbers. These injuries tend to occur around puberty because this is when the physis is most vulnerable to injury. Additionally, it has been found that intensive finger training (campus boarding, a previously known risk factor for epiphyseal fractures) during adolescence can lead to early-onset osteoarthritis of the hand up to a decade later. There is currently a lack of a return-to-climb protocol for youth climbers following a repetitive stress epiphyseal fracture. Because of this gap in the literature, our purpose was to create a structured return-to-play protocol specific to youth climbers who sustained an epiphyseal fracture to the finger. By establishing these guidelines, medical professionals and coaches may be able to guide their athlete to gradually and safely return to sport.

Editorial Commentary: Which Allograft Is Superior for Hip Capsular Reconstruction? Let's Choose the Right Patient Before We Choose the Right Graft.

The hip is an inherently stable joint. Acetabular depth and version, femoral torsion, and congruency of articulation form the pillars of hip stability, with the labrum and capsule serving as secondary stabilizers. The increasing prevalence of capsular deficiency in the setting of revision hip arthroscopy has led to the development of capsular reconstruction techniques. The first step in hip capsular reconstruction, however, is selecting the right patient for the procedure.

Increased Prevalence of Femoroacetabular Impingement in Patients With Proximal Hamstring Tendon Injuries.

PURPOSE: To determine the prevalence of clinically diagnosed femoroacetabular impingement (FAI) in a consecutive series of patients presenting with proximal hamstring tendon injury and to correlate this with pelvic anatomic factors. METHODS: The prevalence of clinically symptomatic cam-, pincer-, and mixed-type and overall FAI was calculated among a consecutive series of patients presenting to a hip preservation clinic with a confirmed clinical and radiographic diagnosis of proximal hamstring tendon injury between 2012 and 2017. The presence of a cam lesion was determined by an alpha angle > 50° on radiographs and computed tomography radial sequences of the head-neck junction and a femoral head-neck offset ratio < 0.18. Clinical diagnoses of osseous impingement were determined according to accepted pathomorphologic signs and measurements. A diagnosis of FAI was confirmed by imaging findings of acetabular overcoverage for pincer-type FAI and the presence of an anterior or lateral cam lesion for cam-type FAI. RESULTS: Overall, 120 hips in 97 patients (mean age, 45 years) were included in this study. A clinical diagnosis of FAI was noted in 70.8% of hips (pincer-type 9.2%, cam-type 40.8%, mixed-type 20.8%), an approximate 2- to 7-fold increased prevalence in comparison with the general population from prior studies. CONCLUSIONS: The prevalence of FAI is high in patients with symptomatic proximal hamstring tendon pathology. Because FAI results in restriction of hip range of motion and altered pelvic tilt, future studies are warranted to investigate whether the presence of FAI acts as a predisposing factor for injury to the hamstring muscle complex. LEVEL OF EVIDENCE: Level IV, case series.

Combined Lateral Osseolabral Coverage Is Normal in Hips With Acetabular Dysplasia.

PURPOSE: To compare the lateral osseolabral coverage between groups of patients with different degrees of acetabular bony coverage using a magnetic resonance imaging parameter known as the combined lateral center-edge angle (cLCEA). METHODS: The cLCEA was measured among a consecutive series of patients presenting to a dedicated hip preservation surgeon with a magnetic resonance imaging scan. The cLCEA was measured using a coronal T1 or proton density image and was defined as the angle subtended by (1) a line through the center of the femoral head and orthogonal to the transverse line passing through the teardrops of both hips and (2) an oblique line drawn from the center of the femoral head to the free edge of the lateral acetabular labrum. The average difference between the lateral center-edge angle (LCEA) and the cLCEA was calculated and compared between groups based on acetabular bony coverage: dysplasia (LCEA <20°), borderline dysplasia (LCEA 20°-24.9°), normal coverage (LCEA 25°-39.9°), and overcoverage (LCEA ≥40°). RESULTS: In total, 341 patients (386 hips) were included. There were no significant differences in cLCEA between hips with normal acetabular coverage and dysplasia (P = .10) or borderline dysplasia (P = .46). Despite the large difference in mean LCEA between dysplasia (14.8° ± 3.9°) and acetabular overcoverage (43.1° ± 2.8°), the mean cLCEA values exhibited only a modest difference (44.7° ± 4.9° vs 52.7° ± 4.5°, respectively). Concordantly, hips with dysplasia exhibited the largest difference between mean LCEA and cLCEA (delta = 29.9° ± 4.7°) and hips with acetabular overcoverage had the smallest difference between measures (9.6° ± 5.2°). CONCLUSIONS: With decreasing acetabular bony coverage, there is increasing labral size such that the total osseolabral coverage, measured by the combined LCEA, remains equivalent between hips with normal acetabular coverage versus dysplasia. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Simultaneous Bilateral Hip Arthroscopy in Adolescent Athletes With Symptomatic Femoroacetabular Impingement.

BACKGROUND: Femoroacetabular impingement represents a common cause of hip pain in adolescents. The purpose of the present study was to evaluate the safety and efficacy of simultaneous bilateral hip arthroscopy for bilateral symptomatic femoroacetabular impingement in adolescent athletes. METHODS: Clinical data were collected in a prospective database on patients who underwent unilateral or simultaneous bilateral hip arthroscopy and included complications, reoperation rate, and return to play time. Differences in International Hip Outcome Tool (iHOT)-12 scores according to hip side and postoperative follow-up time (preoperative, 1.5, 3, 6, 12, and 24 mo) were evaluated using a 2×6 repeated-measures analysis of variance with post hoc repeated-measures 1-way analysis of variance and Bonferroni-corrected paired t tests. RESULTS: In total, 24 patients (36 hips) were studied, of whom 12 underwent simultaneous bilateral hip arthroscopy (24 hips) and a case-matched control group of 12 patients underwent unilateral hip arthroscopy. There were 5 males in each group (41.7%). Average age was 15.7 and 16.5 years in the bilateral and unilateral groups, respectively. No patients were lost to follow-up. In the bilateral group, a significant increase in mean iHOT-12 score was observed between 1.5- and 3-month follow-up (61.8 vs. 82.8, respectively; P=0.003), and 6-, 12-, and 24-month follow-up (91.4, 95.1, and 96.6, respectively, P=0.004). At all follow-up times, there were no significant differences in mean iHOT-12 scores or other outcome measures between bilateral and unilateral cohorts. Time to return to preinjury level of activity was similar between the bilateral and unilateral groups (4.7 vs. 4.9 mo, respectively; P=0.40). One transient lateral femoral cutaneous nerve palsy occurred in each group, though no other complications were documented. No patients required revision surgery by latest follow-up. CONCLUSIONS: Bilateral simultaneous hip arthroscopy is safe and reproducible in adolescent athletes, achieving equivalent outcomes, and similar rehabilitation time when compared with unilateral surgery. LEVEL OF EVIDENCE: Level II-therapeutic study.

Standardizing the Prearthritic Hip Joint Space Width: An Analysis of 994 Hips.

PURPOSE: The purposes of this study were (1) to define a normal prearthritic hip joint space width (JSW) in symptomatic and asymptomatic patients with various degrees of acetabular coverage based on the lateral center edge angle (LCEA) and (2) to determine predictors of JSW using patient-specific variables. METHODS: In a consecutive series of patients presenting to a hip preservation clinic between July 2012 and April 2016, a standard weight-bearing anteroposterior pelvic view was obtained. JSW was defined as the distance between the bony contour of the acetabular rim and femoral head in 2 locations (lateral and medial weight-bearing zone). Hips with severe anatomic deformity, a Tönnis grade >0, or a lateral or medial JSW <2.5 mm were excluded. A linear mixed model analysis was performed in order to determine which variables (age, sex, side, height, weight, symptomatic/asymptomatic, LCEA, and clinical diagnosis) were significantly related to JSW. RESULTS: A total of 994 hips were included. LCEA was found to be a significant predictor of both the lateral and medial JSW, with a decreased JSW associated with increasing degrees of acetabular bony coverage (P < .02). A mean 0.9 mm (20%) difference in medial JSW was found between patients with frank dysplasia (LCEA <20°) compared with those with pincer-type FAI (LCEA ≥40°). There was no difference between symptomatic and asymptomatic hips, either for lateral (asymptomatic: 4.51 ± 0.83 mm; symptomatic: 4.52 ± 0.85 mm; P = .58) or medial JSW (asymptomatic: 4.02 ± 0.96 mm; symptomatic: 3.97 ± 0.84 mm; P = .49). CONCLUSIONS: The LCEA is a significant predictor of hip JSW, with the mean JSW decreasing with increasing degrees of acetabular bony coverage. Joint space is not a major factor in symptomatology in adults with prearthritic hip pain. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Accuracy and Reliability of Computed Tomography and Magnetic Resonance Imaging Compared With True Anatomic Femoral Version.

BACKGROUND: Abnormal torsion of the femur is correlated to lower extremity pathologies. Although computed tomography (CT) scan is the gold standard torsional measurement, magnetic resonance imaging (MRI) is proposed as a viable alternative. Our aim was to determine the accuracy and consistency of MRI and CT femur rotational studies based on 4 described protocols. METHODS: Twelve cadaveric femora were stripped of soft tissue before imaging and physical assessment of torsion. Four advanced imaging series were obtained for each specimen: CT with axial cuts of the femoral neck (CT-axial); CT with oblique cuts of the femoral neck (CT-oblique); MRI with axial cuts of the femoral neck (MR-axial); MRI with oblique cuts of the femoral neck (MR-oblique). Anatomic specimens were placed with the posterior femoral condyles flat on a dissection table for assessment of true torsion with digital images. Three independent reviewers performed all measurements, including true torsion, using imaging software. Bland-Altman analysis was repeated with the data from each reviewer. RESULTS: Interobserver repeatability for all groups was high at 0.95, 0.87, 0.90, 0.97, and 0.92 for CT-axial, CT-oblique, MR-axial, MR-oblique, and true torsion, respectively. CT-axial had the lowest mean difference from clinical imaging for all three observers (all <1 degree) and held the tightest 95% limits of agreement for 2/3 observers. As torsion increases from neutral, MR-oblique linearly overestimates the rotation compared with true torsion. CT-oblique and MR-axial showed slightly greater differences from true torsion compared with CT-axial, but did not reach clinical significance. CONCLUSIONS: CT-axial was both most accurate and reproducible when compared with true torsion of the femur and should be the gold standard imaging modality; however, both MR-axial and CT-oblique were accurate to a level that is likely less than clinical significance. MR-axial images should be used in clinical situations where radiation exposure needs to be limited. MR-oblique images can overestimate true antetorsion and should not be used. CLINIC SIGNIFICANCE: CT-axial followed by MRI-axial is the most accurate and consistent in measuring true torsion of the femur.

Postoperative Imaging in the Setting of Hip Preservation Surgery.

Osteoarthritis of the hip remains a prevalent disease condition that influences ever-changing treatment options. Procedures performed to correct anatomic variations, and, in turn, prevent or slow the progression of osteoarthritis, are aptly referred to as types of hip preservation surgery (HPS). Conditions that predispose individuals to femoroacetabular impingement (FAI), including pincer- and cam-type morphology, and hip dysplasia are specifically targeted in HPS. Common surgical interventions include acetabuloplasty, osteochondroplasty, periacetabular osteotomy (PAO), and derotational femoral osteotomy (DFO). The radiologist's understanding of the surgical approach, pre- and postoperative imaging findings, and common complications of HPS are paramount to providing value to the patient and surgeon. Acetabuloplasty and osteochondroplasty are performed to address pincer- and cam-type morphology in patients with FAI. With both of these HPS techniques, the goal is to restore the normal morphology by resecting excess bone in the acetabulum or femoral head or neck. As a result, a frequently encountered complication is incomplete or excessive resection. Excessive resection can predispose the patient to dislocation in the case of acetabuloplasty and fracture in the case of osteochondroplasty. Iatrogenic injury to adjacent structures such as the ischiofemoral ligament and acetabular cartilage also may occur. Although rare, especially when an arthroscopic approach is used, avascular necrosis remains a risk. Femoral head undercoverage in hip dysplasia is corrected by using PAO, which may be performed as the sole procedure or in conjunction with DFO. Incomplete or excessive rotation during surgery can result in postprocedural complications. As with any orthopedic procedure involving osteotomy, nonhealing is a risk. Iatrogenic injury in the form of fracture or hardware failure also may be seen. ©RSNA, 2016.

The Role of Hip Arthroscopy in Investigating and Managing the Painful Hip Resurfacing Arthroplasty.

PURPOSE: To determine the safety and efficacy of hip arthroscopy performed in the peripheral compartment as a diagnostic and therapeutic treatment option for patients with hip pain after hip resurfacing surgery. METHODS: Indications for hip arthroscopy after hip resurfacing included patients with a symptomatic hip-resurfaced arthroplasties who did not respond to nonoperative treatment. Patients who underwent a hip arthroscopy after a painful hip resurfacing were included with a minimum of 1 year follow-up. Subgroup analysis was performed according to whether an established diagnosis was made before arthroscopic intervention or not. Subjective measures were based on Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores, and results were calculated and analyzed. RESULTS: We included 68 patients (26 male [38%] and 42 female [62%]) who underwent subsequent hip arthroscopy from a population of 978 consecutive hip-resurfaced arthroplasties performed between 1999 and 2010. The average age was 58 (range, 37 to 78 years). The mean follow-up after hip arthroscopy was 3.4 years (range, 12 months to 5.8 years). Patients who had an established diagnosis (n = 41) before hip arthroscopy showed statistical improvement in their WOMAC scores (7 to 2, P < .001). Only 3 (7%) of these 41 patients failed and were converted to a total hip replacement (THR); however, patients who did not have an established diagnosis (n = 27) before undergoing hip arthroscopy showed statistical worsening of the WOMAC (15 to 21, P = .002). Ten (37%) of these 27 patients without a diagnosis failed and needed to be converted to a THR. A significant correlation was found between the collections found on ultrasound (psoas bursa and/or in the hip joint) and the need for synovectomy (P = .01). The overall revision rate to THR after hip resurfacing in our group of patients was 1.3% (n = 13). Female patients were more likely to require postresurfacing hip arthroscopy with 42 (60%) female to only 26 (40%) male patients undergoing this procedure. In our study population, 70% (14/21, P < .05) of patients with hip pain caused by severe metal synovial reaction or metal-on-metal reaction were women. A total of 5 (7%) patients had minor-to-mild complications after hip arthroscopy. CONCLUSIONS: Hip arthroscopy is a safe surgical treatment option for those patients with a painful hip resurfacing arthroplasty. Having an accurate diagnosis before hip arthroscopy improves the likelihood a good outcome. LEVEL OF EVIDENCE: Level IV - therapeutic case series.