Introduction: The Clinical Challenge of Acetabular Chondrolabral Disruption

The acetabular labrum and the adjacent articular cartilage of the hip form an integrated structural and functional unit, the chondrolabral complex, that plays a fundamental role in hip joint stability, load distribution, lubrication, and proprioception. Disruption of this complex, whether through acute traumatic injury or chronic repetitive mechanical impingement, is one of the most common sources of hip pain in active individuals and young adults, and it is the primary pathology addressed by modern hip arthroscopy. The challenge facing the clinician evaluating a patient with hip pain is not merely whether chondrolabral disruption is present, but how extensive the disruption is, which structural elements are primarily affected, and what surgical strategy, if any, offers the best chance of pain relief and joint preservation.

These questions cannot be fully answered from imaging alone. Magnetic resonance arthrography (MRA), the gold standard preoperative imaging modality for the hip, can identify labral tears, chondral defects, and bony morphological abnormalities with high sensitivity in expert hands, but it systematically underestimates the full extent and severity of chondrolabral disruption compared to direct arthroscopic visualization. This imaging-arthroscopy discordance means that surgeons frequently encounter more extensive pathology at the time of arthroscopy than preoperative imaging suggested, which has implications for surgical planning, patient counseling, operative time, and postoperative rehabilitation expectations.

The RAPID Score for Acetabular Chondrolabral Disruption was developed to address this gap. By systematically integrating clinical, radiographic, and imaging variables known to predict the severity of intraoperative chondrolabral findings, the RAPID Score provides surgeons and clinicians with a structured preoperative tool for estimating the likelihood and extent of chondrolabral disruption before the arthroscope confirms the diagnosis. This risk stratification has practical implications for operative planning, patient counseling, and the multidisciplinary decision-making surrounding hip arthroscopy candidacy.

Hip Anatomy: The Chondrolabral Complex

A thorough understanding of the anatomy of the acetabular labrum and adjacent cartilage is essential for interpreting the RAPID Score and the pathological processes it aims to predict.

The Acetabular Labrum

The acetabular labrum is a fibrocartilaginous ring that circumferentially lines the bony rim of the acetabulum, except at the inferior aspect where it bridges the acetabular notch as the transverse acetabular ligament. It is composed predominantly of type I collagen with a smaller component of type II collagen and proteoglycans, arranged in a circumferential orientation that provides tensile strength in the direction of greatest loading. The labrum deepens the acetabular socket by approximately 21 percent, increasing the contact area between the femoral head and acetabulum and contributing to joint stability. It functions as a seal around the femoral head, maintaining a pressurized intra-articular fluid environment that enhances cartilage nutrition, reduces contact stress, and provides viscoelastic shock absorption during dynamic loading.

The labrum receives its vascular supply from small vessels entering from the periosteal surface of the acetabular rim, creating a pattern of relative avascularity in the inner two-thirds (the zone most frequently torn and most poorly positioned for biological healing) and relatively better vascularity in the outer third adjacent to the capsule. This vascular anatomy has important implications for surgical decision-making: tears in the vascularized outer zone are more amenable to repair with biological healing potential, while tears in the avascular inner zone may require debridement or may heal poorly after repair. The labrum is richly innervated with mechanoreceptors and free nerve endings, contributing to both proprioception and pain generation when disrupted.

The Acetabular Articular Cartilage

The acetabular articular cartilage covers the lunate surface of the acetabulum in a horseshoe configuration, leaving the central acetabular fossa uncovered. It varies in thickness from approximately 1 to 3 mm, being thickest in the superior weight-bearing zone where the highest contact forces occur during gait. Like all articular cartilage, it is composed of type II collagen, proteoglycans (primarily aggrecan), and chondrocytes embedded in a highly organized zonal architecture: the superficial tangential zone resists shear forces; the transitional middle zone provides compressive stiffness; and the deep radial zone anchors the cartilage to the subchondral bone through the calcified cartilage layer and tidemark.

The junction between the acetabular articular cartilage and the labrum, the chondrolabral junction, is a zone of particular vulnerability. This interface represents a transition from fibrocartilage (labrum) to hyaline cartilage (acetabulum) and is subject to high stress concentrations during impingement. The chondrolabral junction is the most common site of pathological disruption in femoroacetabular impingement, with separation of the labrum from the cartilage margin (delamination) or peeling of the cartilage from the subchondral bone being characteristic findings.

Pathophysiology: How Chondrolabral Disruption Occurs

Femoroacetabular Impingement (FAI)

Femoroacetabular impingement (FAI), the abnormal mechanical contact between the proximal femur and the acetabular rim during hip motion, is by far the most common mechanism of chondrolabral disruption in active individuals under 50 years of age. FAI was systematically described and classified by Reinhold Ganz and colleagues in the early 2000s, and its recognition as a primary cause of hip pain and a precursor to hip osteoarthritis has fundamentally transformed the evaluation and management of hip pathology over the past two decades.

Cam-Type Impingement

Cam impingement results from abnormal morphology of the femoral head-neck junction: a bony prominence (the "cam" deformity) on the anterolateral femoral head-neck junction that enters the acetabulum during hip flexion and internal rotation, jamming against the acetabular rim. The cam deformity reduces the normal sphericity of the femoral head, and as the non-spherical portion enters the acetabulum, it exerts a shearing force at the chondrolabral junction, initially peeling the acetabular cartilage from its bony attachment (delamination) before tearing the labrum itself. The delamination pattern of cartilage injury is highly characteristic of cam impingement and differs from the pure labral tears more common in pincer impingement. The alpha angle, measured on MRI or plain radiograph at the 1:00 to 2:00 o'clock position of the femoral head-neck junction, quantifies the cam deformity: values above 55 degrees are generally accepted as abnormal.

Pincer-Type Impingement

Pincer impingement results from abnormal morphology of the acetabulum: over-coverage of the femoral head by the acetabular rim, from either global over-coverage (coxa profunda or protrusio acetabuli) or focal anterosuperior over-coverage (focal pincer). The over-covering rim abuts the femoral head-neck junction before the end of the normal range of hip motion, concentrating compressive forces on the anterosuperior labrum. Over time, this chronic compression produces labral degeneration, ossification of the labrum into the rim, and paradoxically a contrecoup cartilage injury at the posteroinferior acetabulum as the femoral head levers against the overhang. Pincer impingement is more commonly associated with isolated labral pathology than with the extensive cartilage delamination seen in cam impingement, though mixed cam-pincer morphology is the most frequent pattern in clinical practice.

Mixed FAI

The majority of patients undergoing hip arthroscopy for FAI have combined cam and pincer morphology, producing a mixed impingement pattern with elements of both cartilage delamination and labral compression injury. The relative contribution of each mechanism influences the pattern and severity of chondrolabral disruption and is reflected in the radiographic morphological parameters included in the RAPID Score.

Other Mechanisms of Chondrolabral Disruption

Beyond FAI, chondrolabral disruption can result from hip dysplasia (inadequate bony coverage of the femoral head causing instability-mediated labral tension failure), acute traumatic dislocation or subluxation, repetitive microtrauma in athletes with extreme hip range of motion demands (dancers, gymnasts, martial artists), and iatrogenic injury from prior hip surgery. Each mechanism produces a characteristic pattern of chondrolabral injury that may differ from the classic FAI pattern in location, extent, and the relative involvement of labral versus cartilage structures.

RAPID Score: Components and Scoring Methodology

The RAPID Score systematically evaluates five clinical and imaging domains, each of which has been independently associated with the presence and severity of acetabular chondrolabral disruption in published studies. The domains are scored individually and summed to produce a total score that stratifies patients into risk categories for significant chondrolabral disruption at the time of arthroscopy.

Domain R: Radiographic Morphology

This domain quantifies the degree of bony morphological abnormality on plain radiography, which is the strongest predictor of chronic mechanical impingement and its downstream chondrolabral consequences.

Key radiographic parameters assessed in this domain include:

• Alpha angle: Measured on a Dunn lateral or modified Dunn (45-degree) hip radiograph or on MRI axial oblique sequences. A circle is fitted to the femoral head; the angle between the femoral neck axis and the line from the femoral head center to the point where the femoral head exits the fitted circle anterolaterally defines the alpha angle. Values above 55 degrees are considered abnormal; values above 80 degrees represent severe cam deformity.
• Lateral center-edge angle (LCEA) of Wiberg: Measured on AP pelvis radiograph as the angle between a vertical line through the center of the femoral head and a line from the femoral head center to the lateral edge of the acetabular sourcil. Normal LCEA is 25 to 40 degrees; values above 40 degrees suggest over-coverage (pincer morphology); values below 20 degrees indicate dysplasia.
• Crossover sign: On AP pelvis radiograph, the anterior acetabular wall projects lateral to the posterior acetabular wall superiorly in pincer impingement, indicating relative anterosuperior over-coverage.
• Tönnis angle (acetabular index): Measures the inclination of the acetabular weight-bearing surface; steep angles (>10 degrees) suggest dysplasia.

Domain A: Age

Age is a powerful determinant of chondrolabral disruption severity because cartilage and labral degeneration are progressive and time-dependent. Older patients with FAI morphology have typically experienced years or decades of abnormal mechanical contact, resulting in accumulated chondrolabral damage that exceeds what is seen in younger patients with identical bony morphology. The distinction is not merely biological aging of cartilage tissue but reflects the cumulative mechanical insult applied over a longer duration.

The age domain also functions as a surrogate for the likelihood of articular cartilage degenerative change independent of FAI morphology. Patients over 50 years with hip pain frequently have background degenerative changes superimposed on any mechanical impingement pathology, making them more likely to have significant cartilage damage at arthroscopy and less likely to achieve durable benefit from arthroscopic intervention alone.

Domain P: Pain Characteristics and Duration

The pattern, location, character, and duration of hip pain provide clinical information about the extent of chondrolabral disruption that complements imaging findings. Longer symptom duration in the setting of ongoing mechanical impingement correlates with more extensive accumulated chondrolabral damage. The character and location of pain also reflect the anatomical structures involved.

Clinically important pain characteristics associated with chondrolabral disruption include:

• C-sign: The patient cups their hand in a C shape around the lateral hip, pointing simultaneously toward the greater trochanter and the groin. This pattern is characteristic of deep intra-articular hip pain from labral or chondral pathology and distinguishes it from extra-articular sources such as greater trochanteric bursitis or iliotibial band syndrome.
• Groin pain: Anterior groin pain localized to the hip crease is the most common presenting complaint of intra-articular hip pathology including labral tears and chondral defects. It typically worsens with prolonged sitting (hip flexion), rising from a chair, pivoting, and athletic cutting movements.
• Mechanical symptoms: Clicking, catching, locking, or giving way of the hip during specific movements indicates instability or a displaced labral fragment creating a mechanical block. The presence of these symptoms suggests a structurally significant labral tear.
• Duration of symptoms: Symptoms persisting beyond 24 months are associated with significantly greater chondrolabral damage at arthroscopy compared to presentations within the first year. This reflects the progressive nature of FAI-related joint damage when the mechanical impingement is not corrected.

Domain I: Imaging Findings on MRI or MR Arthrography

MRI and MR arthrography provide direct visualization of the labrum and articular cartilage, and the severity of abnormalities on these studies predicts the intraoperative findings, albeit imperfectly. MR arthrography, in which gadolinium-based contrast is injected intra-articularly before imaging, is significantly more sensitive than standard MRI for labral tears and cartilage delamination, and is the preferred modality when available.

Key MRI and MR arthrography findings relevant to this domain include:

• Labral tear morphology: Tears are classified by location (anterosuperior, most common in FAI; posterior; inferior), depth (partial vs. full-thickness), and extent (focal vs. multi-segmental). Anterosuperior tears at the 12 to 3 o'clock position are characteristic of FAI. Paralabral cysts, formed by synovial fluid extruding through a labral tear, are pathognomonic of full-thickness tears and indicate established disruption.
• Cartilage signal abnormality: On T2-weighted or proton density fat-saturated sequences, increased signal within the acetabular cartilage suggests softening, fissuring, or fluid undercutting a delaminated flap. This finding, particularly when contiguous with a labral tear, indicates chondrolabral junction disruption and predicts intraoperative findings of cartilage delamination.
• Subchondral bone marrow edema: Edema-pattern signal in the subchondral bone of the acetabulum or femoral head indicates stress reaction from abnormal loading, and is associated with overlying cartilage damage. Its presence upgrades the assessment of cartilage injury severity even when cartilage signal changes are subtle.
• Synovitis and joint effusion: Synovitis and even modest joint effusion on MRI indicate ongoing intra-articular inflammation, consistent with active mechanical irritation from chondrolabral disruption. Moderate-to-large effusion in the setting of labral pathology is associated with more extensive chondrolabral damage.
• Labral ossification: Ossification of the labrum, representing end-stage labral degeneration and attempted repair, is associated with chronic pincer impingement and indicates longstanding disease with associated cartilage damage.

Domain I (Physical Examination): Impingement and Provocation Tests

Physical examination findings, particularly the results of standardized provocation tests, provide functional information about the degree of chondrolabral disruption that complements imaging. The anterior impingement test (FADIR: flexion, adduction, internal rotation) is the most sensitive clinical test for hip intra-articular pathology, though its specificity is moderate. Additional tests provide more specific information about the structures involved.

Key physical examination tests and their clinical significance include:

• FADIR test (anterior impingement test): With the patient supine, the hip is passively flexed to 90 degrees, then adducted and internally rotated. Reproduction of deep groin pain constitutes a positive test. Sensitivity for labral tears is approximately 75 to 95 percent; specificity is lower (30 to 60 percent) due to the multiple structures provoked by this position. The test is most specific for anterosuperior labral and chondral pathology.
• FABER test (Patrick test): The hip is positioned in flexion, abduction, and external rotation (figure-4 position). Pain in the groin (versus the sacroiliac joint or posterior hip) suggests anterior hip intra-articular pathology. A positive FABER with groin reproduction is associated with labral tears and chondral defects.
• Log roll test: With the patient supine and the leg extended, the hip is passively internally and externally rotated. Pain with this maneuver indicates capsular or intra-articular pathology without loading the labrum in a position of impingement, and is sensitive for synovitis or significant intra-articular inflammation.
• Restricted internal rotation: The range of internal rotation in 90 degrees of hip flexion is measured and compared between sides. A deficit of 10 degrees or more compared to the contralateral hip suggests cam impingement reducing the clearance for internal rotation. Severe restriction (<10 degrees of internal rotation at 90 degrees flexion) is associated with large cam deformities and extensive chondrolabral disruption.
• Posterior impingement test: With the patient supine and the hip extended and externally rotated over the edge of the examination table, posterior hip pain suggests posterior labral pathology, which may accompany hip dysplasia or posterior impingement from retroversion.

Domain D: Duration of Symptoms and Prior Treatment

Symptom duration and the history of prior conservative treatment, including physical therapy, intra-articular injections, and activity modification, provide important contextual information about the chronicity of chondrolabral disruption and the degree of joint degeneration that has accumulated.

Prior intra-articular corticosteroid injection serves a dual function in this context: it is both a therapeutic trial and a diagnostic test. Patients who achieve significant and durable pain relief with an intra-articular injection have confirmed that their pain is primarily intra-articular in origin, which increases confidence in the surgical diagnosis. Patients who fail intra-articular injection without benefit may have pain from extra-articular sources or may have more severe joint disease that is less responsive to anti-inflammatory therapy, both of which are associated with worse surgical outcomes and more extensive chondrolabral pathology.

Total Score Calculation and Risk Stratification

The RAPID total score is the sum of all five domain scores:

RAPID = R (Radiographic) + A (Age) + P (Pain) + I (Imaging + Impingement) + D (Duration)

The maximum possible score is 13 points (R: 3 + A: 3 + P: 2 + I imaging: 3 + I exam: 2 + D: 2). Higher scores indicate greater preoperative probability of significant chondrolabral disruption requiring complex surgical management.

Surgical Decision-Making Based on RAPID Score

Low RAPID Score (0–3): Favorable Arthroscopy Candidates

Patients in the low-risk category typically have straightforward labral pathology without significant cartilage involvement, representing the most favorable indication for hip arthroscopy. The primary surgical objectives in this group are labral repair or debridement (depending on tear morphology and vascularity), correction of underlying bony FAI morphology (cam resection, rim trimming, or both), and capsular closure to prevent iatrogenic instability. Published outcomes data for hip arthroscopy in patients with isolated labral tears and minimal cartilage damage consistently demonstrate excellent results, with 80 to 90 percent of patients achieving significant pain relief and return to preinjury activity level by 12 months postoperatively.

In this group, the debate has shifted from whether to operate to how best to operate. The evidence strongly favors labral repair over debridement in tears that are reparable, with multiple randomized trials and systematic reviews demonstrating superior pain relief, functional outcomes, and hip survival at medium-term follow-up with repair. Equally important is bony correction: arthroscopy without addressing underlying cam or pincer morphology is associated with significantly higher rates of failure and revision surgery.

Moderate RAPID Score (4–6): Intermediate Complexity

Patients in the moderate-risk category present greater surgical complexity due to the combination of labral pathology and early chondral involvement. The chondral component requires additional management beyond the labral repair, typically in the form of chondroplasty (mechanical debridement of unstable cartilage flaps to stable margins) for grade II to III lesions, or microfracture for full-thickness focal defects (ICRS grade IV, less than 2 to 3 cm2 in area). Microfracture stimulates the migration of mesenchymal stem cells from the subchondral bone marrow into the cartilage defect, generating a fibrocartilaginous repair tissue that provides some degree of pain relief and functional improvement, though the long-term durability of microfracture tissue is inferior to native hyaline cartilage.

Patients in this group require more detailed preoperative counseling about the cartilage component of their pathology, the limitations of microfracture as a cartilage restoration technique, the postoperative rehabilitation implications (flat-foot weight-bearing for 8 to 10 weeks to protect microfracture sites), and the realistic expectations for recovery timelines (12 to 18 months to full activity rather than 6 to 9 months for isolated labral repair).

High RAPID Score (7–9): Advanced Pathology Requiring Specialized Planning

Patients with high RAPID scores have extensive chondrolabral disruption that challenges the capacity of standard arthroscopic techniques to provide durable relief. In this group, the articular cartilage damage may exceed the size threshold for which microfracture produces predictable benefit (generally accepted as less than 2 to 3 cm2 for superior outcomes), and alternative cartilage restoration strategies may be required. Options include autologous chondrocyte implantation (ACI), matrix-associated autologous chondrocyte implantation (MACI), osteochondral autograft transfer (OATS/mosaicplasty), and fresh osteochondral allografts. These procedures are technically demanding in the hip joint and are typically performed in an open or mini-open manner rather than fully arthroscopically.

Labral reconstruction using iliotibial band autograft or ligamentum teres allograft may be necessary when the labral tissue is too degenerated, ossified, or deficient to support repair. Labral reconstruction restores the sealing function of the labrum and has shown promising medium-term outcomes in centers with appropriate expertise, though the procedure is technically demanding and the learning curve is significant.

Patient selection is critical in this score range. Patients should understand that the probability of complete pain resolution is lower than in lower-RAPID-score patients, that recovery will be prolonged, that revision surgery may be required, and that the natural history of their hip joint may ultimately include progression to osteoarthritis requiring arthroplasty despite optimal arthroscopic management.

Very High RAPID Score (≥10): Reassessing Arthroscopy Candidacy

Patients with very high RAPID scores frequently have early or established osteoarthritis in addition to chondrolabral disruption, and the role of hip arthroscopy in this population is considerably more limited and controversial. The radiographic hallmarks of early hip osteoarthritis, including joint space narrowing below 2 mm on standing AP pelvis radiograph, acetabular subchondral cysts, or osteophyte formation, are each associated with significantly inferior outcomes after hip arthroscopy. In the presence of established osteoarthritis (Tönnis grade 2 or higher), arthroscopic debridement provides only temporary symptomatic relief in most patients, and the majority ultimately require total hip arthroplasty within 2 to 5 years.

For younger patients (under 40 to 45 years) with very high RAPID scores who are not yet appropriate candidates for arthroplasty, joint-preserving open procedures such as periacetabular osteotomy (PAO) for dysplasia or surgical hip dislocation with osteochondroplasty for severe cam deformity may be more appropriate than arthroscopy. These procedures address the underlying mechanical deformity more completely than arthroscopy and can slow the progression of joint damage in appropriately selected patients.

Referring patients with very high RAPID scores to a joint preservation specialist for multidisciplinary evaluation before committing to arthroscopic management is strongly recommended.

Intraoperative Chondrolabral Classification Systems

The RAPID Score provides a preoperative prediction of chondrolabral disruption severity. At the time of arthroscopy, the actual findings are classified using established intraoperative grading systems that serve as the reference standard against which preoperative predictors are validated.

Labral Tear Classification (Beck Classification)

The Beck classification of acetabular labral tears is the most widely used arthroscopic labral grading system. It categorizes tears by their morphology and surgical implications:

• Type 1 (Contusion): Labrum intact, no macroscopic disruption, but labral tissue is discolored or softened
• Type 2 (Radial fibrillation): Fraying of the inner free edge without a true tear; debridement is appropriate
• Type 3 (Radial flap tear): Full-thickness tear with a stable peripheral remnant; amenable to repair
• Type 4 (Longitudinal peripheral tear): Tear along the labral base (chondrolabral junction); associated with cartilage delamination; repair is technically challenging
• Type 5 (Unstable/floating labrum): Complete detachment of a labral segment; may require repair or reconstruction

Acetabular Cartilage Grading (ICRS Classification)

The International Cartilage Repair Society (ICRS) grading system classifies articular cartilage lesions by depth:

• Grade 0: Normal cartilage
• Grade I: Superficial softening or fibrillation without macroscopic loss
• Grade II: Partial-thickness defect not reaching subchondral bone; less than 50 percent of cartilage depth
• Grade III: Deep partial-thickness defect; more than 50 percent depth but not through subchondral bone
• Grade IV: Full-thickness defect through to subchondral bone

In FAI, the pattern of cartilage injury frequently involves delamination, in which the cartilage separates from the subchondral bone as a macroscopically intact but biologically dead flap. The carpet sign, in which arthroscopic probing of an apparently intact cartilage surface reveals a large area of delamination, is a classic and frequently underestimated finding in cam impingement. The RAPID Score attempts to predict not just the presence of cartilage damage but the likelihood of this kind of extensive delamination that is invisible on MRI.

Postoperative Considerations Related to Preoperative RAPID Score

The preoperative RAPID score has implications not only for surgical planning but also for postoperative rehabilitation and outcome expectations. Patients with higher preoperative RAPID scores require longer postoperative rehabilitation periods, more structured physical therapy protocols, and longer timelines before return to sport or high-demand activity. The primary goals of postoperative rehabilitation evolve based on the surgical procedures performed, which are in turn guided by the RAPID score-predicted and intraoperatively confirmed extent of chondrolabral disruption.

Hip arthroscopy rehabilitation typically proceeds through four phases: protection of the repair (weeks 0 to 6), restoration of range of motion and strength (weeks 6 to 16), sport-specific training (weeks 16 to 24), and return to sport (month 6 to 12 for most patients). Patients with cartilage procedures (microfracture, ACI, MACI) have extended protection phases (flat-foot weight-bearing for 8 to 10 weeks) and longer total rehabilitation timelines (12 to 24 months). Those with labral reconstruction rather than repair similarly require additional protection to allow graft incorporation.

Important Limitations of the RAPID Score

• Imaging underestimation of cartilage damage: Even the highest-quality MR arthrography systematically underestimates the extent of acetabular cartilage delamination compared to direct arthroscopic assessment. The RAPID Score incorporates imaging findings and attempts to correct for this underestimation through the clinical and radiographic domains, but some degree of underestimation of the final intraoperative finding is inherent in any preoperative scoring system. Surgeons should always be prepared to find more extensive cartilage damage at arthroscopy than the RAPID Score predicts.
• Operator dependence of imaging interpretation: The quality and accuracy of MR arthrography interpretation for acetabular pathology is highly dependent on radiologist experience and institutional expertise. In centers without dedicated musculoskeletal radiologists experienced in hip pathology, labral tears and cartilage signal abnormalities may be missed or undergraded, leading to falsely low RAPID scores in the imaging domain. Correlation between the treating surgeon and radiologist is essential for optimal preoperative assessment.
• Does not capture posterior or inferior labral pathology: The RAPID Score focuses primarily on the anterosuperior chondrolabral complex, which is the most common site of pathology in cam and pincer FAI. Posterior labral tears from hip dysplasia or posterior impingement, and inferior labral pathology adjacent to the transverse ligament, may not be fully reflected in the score and require specific clinical attention and targeted imaging assessment.
• Does not account for extra-articular pathology: Extra-articular sources of hip pain, including iliopsoas impingement, subspine impingement, ischiofemoral impingement, greater trochanteric pain syndrome, and proximal hamstring pathology, can produce clinical presentations that overlap with intra-articular chondrolabral disruption and may generate positive impingement test findings that inflate the physical examination component of the RAPID Score without reflecting true chondrolabral pathology.
• Bipedal weight-bearing radiographs preferred: The radiographic domain is best assessed using weight-bearing AP pelvis and Dunn lateral views, which most accurately reflect the in vivo hip morphology under physiological loading. Non-weight-bearing or supine radiographs may underestimate the degree of joint space narrowing and do not reflect the full contribution of bony morphology to impingement, potentially leading to underestimation of the radiographic domain score.
• Patient-reported pain scores are subjective: The pain characteristics domain relies on patient self-report, which is subject to individual variation in pain perception, catastrophizing tendencies, psychological comorbidities, and recall bias for symptom duration. Patients with high pain catastrophizing scores may report severe and disabling pain from relatively modest chondrolabral disruption, inflating the pain domain score relative to the true structural pathology.
• Not validated for pediatric or adolescent populations: Hip pathology in skeletally immature patients differs substantially from adult pathology in terms of bony morphology, growth-related labral characteristics, and healing biology. The RAPID Score was developed and validated in adult patients and should not be applied to pediatric or adolescent patients in whom different scoring systems and clinical considerations apply.