HIP ARTHROSCOPY
Sports Medicine | FAI Treatment | Labral Repair | Traction Essential | Nerve Protection Critical
FEMOROACETABULAR IMPINGEMENT (FAI) CLASSIFICATION
Critical Must-Knows
- Cam = femoral-based (alpha angle greater than 55°); Pincer = acetabular-based (overcoverage)
- Mixed FAI is most common (80%) - address both cam and pincer components
- Traction essential for central compartment - 25-50lbs force, break seal with internal rotation
- Maximum 2 hours traction - risk of nerve injury (pudendal, sciatic) increases significantly
- Lateral femoral cutaneous nerve at risk with anterolateral portal
Examiner's Pearls
- "Alpha angle greater than 55° on axial MRI indicates cam morphology
- "Positive anterior impingement test (FADIR) is most sensitive clinical sign
- "Always break the vacuum seal with longitudinal traction plus internal rotation before distraction
- "Lateral femoral cutaneous nerve crosses 1-2cm distal and medial to ASIS
Clinical Imaging
Imaging Gallery
Arthroscopic Labral Repair
Critical Hip Arthroscopy Exam Points
Traction Complications
Maximum traction time 2 hours - pudendal nerve most at risk (17% transient neurapraxia). Monitor perineal post pressure and use well-padded post. Intermittent release if prolonged case. Sciatic nerve also at risk with excessive force.
Portal Safety
Lateral femoral cutaneous nerve crosses 1-2cm distal and medial to ASIS - at risk with anterolateral portal. Superior gluteal nerve can be injured with proximal portal placement. Establish portals under fluoroscopic guidance with air arthrogram.
Alpha Angle
Cam morphology defined as alpha angle greater than 55° on axial MRI or cross-table lateral radiograph. Measured as angle between femoral neck axis and point where head-neck junction exceeds head radius. Normal is less than 50°.
Central vs Peripheral
Central compartment (under traction): labrum, acetabular cartilage, ligamentum teres, femoral head. Peripheral compartment (without traction): head-neck junction, medial synovial fold, zona orbicularis. Both compartments need assessment.
At a Glance - FAI Types and Treatment
| FAI Type | Pathoanatomy | Imaging Finding | Surgical Treatment |
|---|---|---|---|
| Cam | Femoral head-neck asphericity (bump) | Alpha angle greater than 55° | Osteochondroplasty (bump resection) |
| Pincer | Acetabular overcoverage | CE angle greater than 40°, crossover sign | Rim trimming plus or minus labral repair |
| Mixed | Both cam and pincer (80% of cases) | Combined findings | Address both components |
CAM vs PINCERFAI Types - 'CAM vs PINCER'
Memory Hook:CAM = bump on femoral head (young males). PINCER = rim pinches labrum (middle-aged females)!
AAPHip Arthroscopy Portals - 'AAP'
Memory Hook:AAP = Anterolateral, Anterior, Posterolateral - the three standard hip arthroscopy portals!
SFLPNerves at Risk - 'SFLP'
Memory Hook:SFLP = Sciatic, Femoral (rare), Lateral cutaneous (common), Pudendal (traction)!
2-25-6Traction Safety - '2-25-6'
Memory Hook:Remember 2-25-6: 2 hours max, 25lbs minimum, 6mm distraction needed!
Overview
Hip arthroscopy is a minimally invasive surgical technique for diagnosing and treating intra-articular and periarticular hip pathology. The primary indication is femoroacetabular impingement (FAI) with associated labral tears, though indications continue to expand.
Epidemiology of FAI:
- Prevalence: 10-15% of general population have imaging findings of FAI; most are asymptomatic
- Symptomatic FAI: Presents in athletes and active individuals, typically 20-45 years
- Sex distribution: Cam more common in males; Pincer more common in females; Mixed most common overall
- Athletic association: High-risk sports include ice hockey, soccer, martial arts, ballet
Pathophysiology:
- Cam mechanism: Aspherical femoral head-neck junction causes outside-in abrasion of acetabular cartilage during flexion and internal rotation. The abnormal convexity shears against the labrum and cartilage.
- Pincer mechanism: Acetabular overcoverage causes labral crush injury and countrecoup lesions on posterior acetabulum. Overcoverage may be global (coxa profunda) or focal (acetabular retroversion).
- Natural history: Untreated FAI leads to progressive cartilage damage and eventual osteoarthritis
Indications for Hip Arthroscopy:
- Femoroacetabular impingement (cam, pincer, or mixed)
- Labral tears
- Chondral lesions (debridement, microfracture)
- Ligamentum teres tears
- Loose bodies
- Synovial disorders (PVNS, synovial chondromatosis)
- Hip instability (capsular plication)
- Iliopsoas tendon release
Pathophysiology and Mechanisms
Hip Joint Anatomy: The hip is a ball-and-socket joint with inherent bony stability enhanced by the acetabular labrum, capsule, and ligaments. The femoral head is covered by hyaline cartilage except at the fovea (ligamentum teres attachment).
Labrum:
- Fibrocartilaginous ring attached to the acetabular rim
- Deepens the acetabulum by 21% and increases surface area by 28%
- Creates a suction seal that provides joint stability
- Blood supply from superior gluteal, inferior gluteal, and obturator vessels
- Vascularity is better peripherally than centrally (important for repair)
Capsule and Ligaments:
- Iliofemoral ligament (Y-ligament of Bigelow): strongest ligament, anterior
- Pubofemoral ligament: inferior, limits abduction
- Ischiofemoral ligament: posterior, limits internal rotation
- Zona orbicularis: circular fibers around femoral neck
Neurovascular Structures:
- Femoral neurovascular bundle: anterior, protected by iliopsoas
- Lateral femoral cutaneous nerve: crosses 1-2cm distal and medial to ASIS
- Superior gluteal nerve: exits above piriformis, at risk with proximal portals
- Sciatic nerve: posterior, at risk with traction and posterior portals
FAI Pathoanatomy:
Cam Morphology:
- Abnormal bump at femoral head-neck junction (anterosuperior most common)
- Results from developmental abnormality during skeletal maturation
- Alpha angle greater than 55° is diagnostic
- Causes outside-in cartilage abrasion during flexion/internal rotation
Pincer Morphology:
- Acetabular overcoverage (global or focal)
- Center-edge angle greater than 40° suggests overcoverage
- Crossover sign on AP pelvis indicates focal retroversion
- Causes labral crush injury and countrecoup posterior cartilage damage
Classification
Femoroacetabular Impingement Classification:
Cam-type FAI results from femoral-based pathology where an aspherical femoral head-neck junction (bump) impinges against the acetabular labrum and cartilage during hip flexion and internal rotation.
Key features: Alpha angle greater than 55° on axial imaging. Bump typically anterosuperior. More common in young athletic males. Causes outside-in cartilage abrasion pattern. Treatment involves osteochondroplasty (bump resection) to restore sphericity.
Labral Tear Classification (Seldes):
- Type 1: Detachment of labrum from acetabular cartilage (most common)
- Type 2: Cleavage plane within labral substance
Beck Cartilage Damage Classification:
- Grade 0: Normal cartilage
- Grade 1: Softening (malacia)
- Grade 2: Partial thickness defect
- Grade 3: Full thickness defect
- Grade 4: Exposed subchondral bone
Acetabular Rim Classification:
- Focal pincer: Retroversion of superior acetabulum
- Global pincer: Coxa profunda/protrusio acetabuli
Clinical Assessment
History:
Classic FAI presentation is a young athletic patient with activity-related groin pain, often with clicking, catching, or giving way. Pain typically insidious onset, worse with prolonged sitting, pivoting activities, and hip flexion.
Common symptoms: Deep anterior groin pain (C-sign where patient cups hand over greater trochanter). Pain with prolonged sitting (theater sign). Pain with hip flexion activities (squatting, stairs). Mechanical symptoms (clicking, catching, locking).
Physical Examination:
Observation: Observe gait for Trendelenburg or antalgic pattern. Note pelvic obliquity and limb length. Assess hip flexion contracture.
Range of motion: Compare to contralateral side. FAI typically shows decreased internal rotation in flexion. Measure flexion, extension, abduction, adduction, internal and external rotation.
FADIR Test
The FADIR (anterior impingement) test is the most sensitive clinical test for FAI. Position: supine with hip and knee at 90° flexion, then passively adduct and internally rotate. Positive test reproduces the patient's groin pain. While sensitive (95%), it has low specificity - must correlate with imaging.
Investigations
Plain Radiographs:
AP Pelvis: Essential initial view. Assess center-edge angle, crossover sign, posterior wall sign. Must have proper positioning (coccyx 1-3cm above symphysis).
Lateral views: Cross-table lateral (Dunn view) or frog-leg lateral. Assess alpha angle, head-neck offset.
MRI and MR Arthrogram:
Standard MRI: Evaluates labrum, cartilage, and periarticular soft tissues. Axial oblique views best for alpha angle measurement.
MR Arthrogram: Gold standard for labral pathology. Intra-articular gadolinium improves labral tear detection. Sensitivity greater than 90% for labral tears.
Radial MRI: Series of views radiating from femoral neck axis. Best for comprehensive assessment of cam lesion location.
CT Scan:
3D CT: Provides excellent bony detail of cam and pincer morphology. Useful for surgical planning. Less radiation with low-dose protocols.
Diagnostic Injection:
Intra-articular injection of local anesthetic under fluoroscopic guidance can confirm intra-articular source of pain. Greater than 50% pain relief suggests intra-articular pathology.
Non-Operative Management
Indications for Non-Operative Treatment:
- Mild symptoms with minimal functional limitation
- Patient preference
- Significant osteoarthritis (relative contraindication to arthroscopy)
- Medical contraindications to surgery
- Initial management while diagnosis is being confirmed
Non-Operative Protocol:
Activity modification: Avoid aggravating positions (deep flexion, prolonged sitting). Physical therapy: Core and hip strengthening, focus on gluteal activation. NSAIDs: For symptomatic relief. Education: Explain pathophysiology and natural history.
Advance rehabilitation: Progressive hip strengthening program. Sport-specific modification: Identify and modify aggravating activities. Injection therapy: Consider intra-articular corticosteroid if indicated. Reassess: Evaluate response to conservative treatment.
Evaluate response: If improved, continue activity modification and maintenance program. If symptoms persist: Consider surgical intervention if appropriate candidate. Shared decision-making: Discuss risks and benefits of surgery vs continued non-operative care.
Injection Considerations
While intra-articular corticosteroid injections may provide temporary relief, they do not address the underlying mechanical problem. Some evidence suggests repeated injections may negatively affect cartilage and outcomes of subsequent surgery. Use judiciously and primarily as a diagnostic tool.
Management Algorithm
Decision-Making Framework for Hip Arthroscopy:
Clinical Assessment: Positive FADIR test with anterior groin pain in a young active patient. Correlate with imaging findings of cam (alpha greater than 55°) or pincer (CE greater than 40°) morphology. MR arthrogram to assess labrum.
Diagnostic Injection: Greater than 50% pain relief with intra-articular local anesthetic confirms intra-articular source and predicts good surgical outcome.
Key Decision Points:
- Joint space greater than 2mm → Good candidate for arthroscopy
- Joint space less than 2mm with arthritis → Consider arthroplasty
- Positive impingement test + positive injection → Best outcomes
- Mixed FAI → Must address both components
Surgical Management
Patient Positioning:
Supine positioning on fracture table is most common. Patient supine with perineal post well-padded. Operative limb in traction boot. Contralateral limb in padded post or abducted in leg holder.
Advantages: Familiar position, easier fluoroscopy, better anterior access. Disadvantages: Perineal post pressure risk.
Traction and Joint Access:
Traction Requirements:
- Force: 25-50 pounds typically needed
- Technique: Apply longitudinal traction, then internal rotation to break vacuum seal
- Confirmation: Fluoroscopic confirmation of 6mm distraction minimum
- Time limit: Maximum 2 hours - release if prolonged case
Portal Establishment:
Standard Portals:
- Anterolateral (AL): Primary viewing portal, 1cm anterior and superior to greater trochanter tip
- Anterior: Primary working portal, intersection of ASIS horizontal line and GT vertical line
- Posterolateral (PL): 1cm posterior and superior to GT, supplementary viewing/working
Technique: Establish portals under fluoroscopic guidance with air arthrogram. Use spinal needle to confirm trajectory. Make skin incision, then blunt trocar insertion to avoid nerve injury.
Central Compartment Procedures:
- Labral repair: Suture anchors for peripheral labral tears
- Labral debridement: For non-repairable tears
- Acetabular rim trimming: For pincer lesions
- Microfracture: For focal cartilage defects
- Ligamentum teres debridement: For symptomatic tears
- Loose body removal
Peripheral Compartment Procedures:
- Osteochondroplasty: Cam lesion resection to restore head-neck offset
- Capsulotomy management: Repair or plication as needed
- Iliopsoas release: If symptomatic internal snapping hip
Complications
Nerve Injuries:
Nerve Injuries in Hip Arthroscopy
| Nerve | Mechanism | Clinical Finding | Prevention |
|---|---|---|---|
| Pudendal nerve | Perineal post pressure (17% transient) | Perineal numbness, impotence | Well-padded post, intermittent release, less than 2hr traction |
| Lateral femoral cutaneous | Anterolateral portal injury | Meralgia paresthetica (lateral thigh numbness) | Portal placement 1-2cm from ASIS, blunt dissection |
| Sciatic nerve | Excessive traction, posterior portals | Posterior thigh numbness, foot drop | Limit traction force and time, careful posterior portals |
| Superior gluteal nerve | Proximal portal placement | Gluteus medius weakness, Trendelenburg | Stay distal to piriformis, avoid proximal portals |
Other Complications:
- Fluid extravasation: Risk of abdominal compartment syndrome with prolonged cases
- Femoral neck fracture: Excessive osteochondroplasty (greater than 30% neck circumference)
- Instability: Excessive rim trimming or capsular damage
- Heterotopic ossification: 1-5% incidence, use NSAIDs prophylaxis
- AVN: Rare, associated with lateral epiphyseal vessel damage
- Infection: Less than 1%
- DVT: Standard VTE prophylaxis recommended
Pudendal Nerve Protection
The pudendal nerve is the most commonly injured nerve in hip arthroscopy (17% transient neurapraxia). Prevention: use well-padded, wide perineal post; limit traction time to less than 2 hours; intermittently release traction in prolonged cases; use lateral positioning to eliminate perineal post.
Rehabilitation
Post-Operative Protocol:
Weight-bearing: Typically 20lbs flat-foot weight-bearing for 2-4 weeks (longer if microfracture). ROM restrictions: Limit hip flexion to 90°, avoid FADIR position for 4-6 weeks. CPM: Consider continuous passive motion machine. Goals: Protect repair, control inflammation, maintain ROM.
Progress weight-bearing: Advance to full as tolerated. ROM: Progress to full ROM. Strengthening: Aquatic therapy, stationary bike, hip strengthening (avoid impingement positions). Goals: Restore ROM, begin strengthening, normalize gait.
Activities: Progress to elliptical, swimming, functional exercises. Strengthening: Progressive resistance training. Sport-specific: Begin sport-specific training at 12+ weeks. Return to sport: Typically 4-6 months depending on procedure and sport.
Procedure-Specific Considerations:
Labral repair:
- Protect repair for 4-6 weeks with ROM restrictions
- Avoid FADIR position during healing
- Full return to sport: 4-6 months
Microfracture:
- Protected weight-bearing 6-8 weeks
- CPM encouraged for cartilage healing
- Return to sport: 6-12 months
Osteochondroplasty alone:
- Earlier weight-bearing (2 weeks)
- Less ROM restriction needed
- Return to sport: 3-4 months
Outcomes and Prognosis
Short-Term Outcomes:
- Patient satisfaction: 85-90% satisfaction at 2 years
- Return to sport: 80-90% return to sport, 70-80% at same level
- Pain improvement: Significant improvement in pain scores (70-80% reduction)
- Functional improvement: Improved modified Harris Hip Score in 85%+
Long-Term Outcomes:
Outcomes by Cartilage Status
| Cartilage Status | Short-term Outcome | Long-term Outcome |
|---|---|---|
| Normal cartilage (Beck 0-1) | Excellent (over 90% good/excellent) | Over 90% hip preservation at 10 years |
| Moderate damage (Beck 2) | Good (75-85% good/excellent) | 70-80% hip preservation at 10 years |
| Severe damage (Beck 3-4) | Fair (50-60% good/excellent) | 50-60% hip preservation at 10 years |
Prognostic Factors:
Favorable:
- Young age (less than 40 years)
- Minimal osteoarthritis (Tonnis 0-1)
- Preserved joint space (greater than 2mm)
- Labral repair (vs debridement)
- Positive injection response pre-operatively
Unfavorable:
- Advanced osteoarthritis
- Joint space less than 2mm
- Full-thickness cartilage loss
- Age greater than 50 years
- Significant acetabular dysplasia
Special Considerations
Borderline Dysplasia:
- Center-edge angle 20-25° is borderline
- May benefit from arthroscopy if FAI component present
- Higher failure rate than non-dysplastic hips
- Consider periacetabular osteotomy (PAO) if significant dysplasia
Revision Hip Arthroscopy:
- Success rates lower than primary (60-70%)
- Most common reasons for failure: inadequate cam resection, missed pincer, untreated labral tear
- Better outcomes if clear identifiable pathology for revision
Hip Arthroscopy in Adolescents:
- FAI morphology develops during skeletal maturation
- Arthroscopy may be considered in skeletally mature adolescents
- Must ensure physes are closed before aggressive osteochondroplasty
Labral Reconstruction:
- Indicated when labrum is deficient and cannot be repaired
- Options: iliotibial band autograft, tensor fascia lata, allograft
- Emerging technique with promising early results
Associated Hip Instability:
- Can result from excessive capsulotomy or rim trimming
- Capsular plication may be needed
- Important to balance impingement correction with stability preservation
Evidence Base
Hip Arthroscopy vs Physiotherapy - UK FASHIoN Trial
- Randomized trial of 348 patients with FAI
- Hip arthroscopy + PT vs PT alone
- Arthroscopy group had better outcomes at 12 months
- iHOT-33 score improvement: 27.3 vs 14.0 points
- Cost-effective at 12-month follow-up
Labral Repair vs Debridement Outcomes
- Matched cohort study of labral repair vs debridement
- Significantly better outcomes with labral repair
- mHHS 88 (repair) vs 81 (debridement)
- Revision rate lower with repair (4% vs 21%)
Alpha Angle and Cam Morphology
- Described alpha angle measurement technique
- Normal alpha angle less than 50°
- Cam morphology alpha greater than 55°
- Established radiographic criteria for cam FAI
Outcomes Based on Pre-operative Joint Space
- Joint space less than 2mm had significantly worse outcomes
- Conversion to THA rate higher with joint space narrowing
- Joint space greater than 2mm: 90% good outcomes at 2 years
- Joint space less than 2mm: 50% required THA at 2 years
Traction Complications and Pudendal Nerve
- 17% incidence of transient pudendal neurapraxia
- Traction time and force correlated with nerve injury
- Symptoms resolved in all cases by 6 weeks
- Recommended limiting traction time to less than 2 hours
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Young Athlete with Groin Pain
"A 25-year-old male professional soccer player presents with 6 months of right groin pain that is worse with kicking and sprinting. He describes a deep anterior hip pain that is aggravated by prolonged sitting."
History: The presentation is classic for FAI in a young athlete. I would establish the exact location of pain (C-sign suggests intra-articular), onset and duration (insidious over 6 months suggests impingement rather than acute labral tear), aggravating factors (kicking involves hip flexion/internal rotation - classic impingement position), and mechanical symptoms (clicking suggests labral pathology). I would ask about prior injuries and treatments attempted.
Examination: I would assess gait, hip ROM (expect decreased internal rotation in flexion), and perform provocative tests. FADIR test (anterior impingement) is most sensitive - positive if reproduces groin pain with hip flexion, adduction, and internal rotation. FABER test assesses labrum and SI joint. Log roll test assesses intra-articular pathology. I would also examine the spine, SI joints, and perform a hernia check.
Investigations: AP pelvis and cross-table lateral radiographs to assess for cam (alpha angle greater than 55°) and pincer (CE angle greater than 40°) morphology. MR arthrogram is gold standard for labral evaluation. Diagnostic intra-articular injection can confirm intra-articular source of pain (greater than 50% relief predicts good surgical outcome).
Management: Initial non-operative trial (3-6 months) with activity modification, physiotherapy, and NSAIDs. If imaging confirms FAI and symptoms persist despite conservative management with positive injection response, hip arthroscopy is indicated. Surgical goals: osteochondroplasty for cam lesion, labral repair if torn, address any pincer component.
Portal Anatomy and Nerve Risk
"You are planning hip arthroscopy on a patient with confirmed FAI and labral tear. The examiner asks you to describe your portal placement and the nerves at risk."
Standard Portals: I use three standard portals for hip arthroscopy. The anterolateral portal is my primary viewing portal, placed 1cm anterior and superior to the greater trochanter tip. The anterior portal is my primary working portal, placed at the intersection of a horizontal line from the ASIS and a vertical line from the greater trochanter. The posterolateral portal is placed 1cm posterior and superior to the greater trochanter tip for supplementary viewing and working.
Nerves at Risk: The lateral femoral cutaneous nerve is at greatest risk with the anterior portal - it crosses approximately 1-2cm distal and medial to the ASIS. Injury causes meralgia paresthetica (lateral thigh numbness). Prevention involves staying more than 2cm from ASIS and using blunt dissection after skin incision.
Additional Nerve Considerations: The pudendal nerve is at risk from perineal post pressure during traction (17% transient neurapraxia). I limit traction time to 2 hours and use a well-padded, wide post. The sciatic nerve is at risk with excessive traction force or posteriorly directed portals. The superior gluteal nerve exits above piriformis and is at risk with proximal portal placement - I stay below the level of the piriformis insertion.
Portal Technique: I establish portals under fluoroscopic guidance. First, I inject the joint with saline and air to create an air arthrogram. I use a spinal needle to confirm trajectory before making skin incisions. After skin incision, I use blunt trocar insertion to protect nerves.
Cam vs Pincer Morphology
"You are shown radiographs of a hip. The examiner asks you to differentiate between cam and pincer morphology and describe how you would measure the relevant angles."
Cam Morphology Assessment: Cam FAI is femoral-based pathology caused by an aspherical bump at the femoral head-neck junction, typically anterosuperior. The diagnostic measurement is the alpha angle, measured on an axial view (cross-table lateral or axial MRI). I draw a line along the femoral neck axis, then identify the point where the head-neck junction exceeds the radius of the femoral head. The alpha angle is measured between the neck axis and a line from the femoral head center to this point. Normal is less than 50°, cam morphology is greater than 55°.
Pincer Morphology Assessment: Pincer FAI is acetabular-based from overcoverage. For global overcoverage, I measure the center-edge (CE) angle on the AP pelvis - the angle between a vertical line through the femoral head center and a line to the lateral acetabular edge. Normal is 25-40°, pincer is greater than 40°. For focal retroversion, I look for the crossover sign where the anterior acetabular wall crosses the posterior wall before the lateral edge, creating a figure-8 pattern.
Mixed Morphology: Mixed FAI (both cam and pincer) is present in approximately 80% of cases. Both components must be identified and addressed surgically. This requires osteochondroplasty for the cam lesion and rim trimming with labral management for the pincer component.
Clinical Correlation: Cam morphology is more common in young athletic males and causes outside-in cartilage abrasion. Pincer morphology is more common in middle-aged females and causes labral crush injury with countrecoup posterior cartilage damage.
Traction Complications
"During hip arthroscopy, the anesthetist informs you that you have been operating for 2.5 hours with traction continuously applied. They ask about traction-related complications."
Immediate Concern: This case has exceeded the recommended 2-hour maximum traction time. My primary concern is traction-related nerve injury, particularly to the pudendal nerve. The pudendal nerve has a 17% incidence of transient neurapraxia even with appropriate technique, and this risk increases significantly beyond 2 hours.
Other Nerves at Risk: The sciatic nerve is also at risk with prolonged traction, particularly with higher traction forces. Additionally, the femoral nerve and lateral femoral cutaneous nerve can be affected by sustained traction.
Immediate Actions: If I have completed the central compartment work, I would release traction immediately and proceed with peripheral compartment work (cam resection) which does not require traction. If central compartment work is incomplete, I would release traction for at least 10 minutes before reapplying, and work as efficiently as possible to complete the case.
Prevention Strategies: For future cases, I monitor traction time closely and plan for intermittent release every 1.5-2 hours. I use a well-padded, wide perineal post and minimum necessary traction force. In very prolonged or complex cases, consider lateral positioning to eliminate the perineal post entirely. Pre-operative planning and surgical efficiency help minimize traction time.
Post-operative Management: I will examine the patient post-operatively for perineal numbness and document findings. If neurapraxia is present, I will counsel the patient that this typically resolves within 6 weeks but can take up to 6 months.
Poor Surgical Candidate
"A 55-year-old woman presents with hip pain and imaging shows FAI with a joint space of 1.5mm and Tonnis grade 2 osteoarthritis. She is keen for hip arthroscopy to avoid hip replacement."
Assessment of Candidacy: This patient has several factors that predict poor outcomes from hip arthroscopy. Her joint space of 1.5mm (less than 2mm threshold), Tonnis grade 2 osteoarthritis, and age of 55 are all unfavorable prognostic factors. Studies show that patients with joint space less than 2mm have a 50% conversion to THA within 2 years.
Counseling Discussion: I would explain that while I understand her desire to preserve her native hip, hip arthroscopy is unlikely to provide lasting benefit in her situation. The outcomes data show that patients with advanced arthritis and joint space narrowing have significantly higher failure rates and often require total hip replacement within a few years anyway.
Options Presented: I would present her options: (1) Continued non-operative management with activity modification, physiotherapy, NSAIDs, and potentially intra-articular injections - this may provide symptomatic relief but will not halt disease progression. (2) Total hip arthroplasty - this is the most predictable option for lasting pain relief and functional improvement in her situation. (3) Hip arthroscopy - I would explain this carries significant risk of failure and may not delay arthroplasty, but if she strongly prefers, we could discuss with understanding of realistic expectations.
Realistic Expectations: If she still wishes to pursue arthroscopy, I would ensure she understands that the procedure may provide temporary improvement but has approximately 50% chance of requiring THA within 2 years. She must accept this possibility before proceeding.
MCQ Practice Points
Exam Pearl
Q: What are the radiographic definitions of Cam and Pincer FAI? A: Cam FAI is defined by an alpha angle greater than 55 degrees (femoral side). Pincer FAI is defined by a Center-Edge (CE) angle greater than 40 degrees or a crossover sign (acetabular side).
Exam Pearl
Q: Which nerve is most commonly injured during hip arthroscopy? A: The Pudendal nerve (17% incidence of transient neurapraxia) due to perineal post traction. The Lateral Femoral Cutaneous Nerve (LFCN) is most at risk from anterior portal placement.
Exam Pearl
Q: What are the traction safety limits? A: Traction should be limited to less than 2 hours duration and minimum necessary force (typically 25-50lbs) to reduce neurapraxia risk.
Exam Pearl
Q: What joint space width predicts poor outcomes? A: Joint space less than 2mm is a strong predictor of failure and conversion to Total Hip Arthroplasty (50% within 2 years).
Exam Pearl
Q: What is the most sensitive physical exam test for FAI? A: The FADIR test (Flexion, Adduction, Internal Rotation). It is highly sensitive (95%) but has low specificity.
Australian Context
Hip arthroscopy in Australia is typically performed by orthopaedic surgeons with sports medicine or hip subspecialty training. The procedure is performed in major metropolitan centers with access to specialized equipment including fluoroscopy and traction tables.
The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) tracks outcomes of hip arthroscopy procedures. Data suggests that patients who subsequently require total hip arthroplasty after hip arthroscopy have similar outcomes to those having primary THA, supporting appropriate patient selection.
Femoroacetabular impingement is increasingly recognized in Australian athletic populations, particularly in sports requiring repetitive hip flexion such as Australian Rules Football, soccer, and cycling. Hip arthroscopy services are available through both public and private systems, with rehabilitation typically provided by sports physiotherapists.
HIP ARTHROSCOPY
High-Yield Exam Summary
FAI Classification
- •Cam = femoral bump, alpha greater than 55°, young males
- •Pincer = acetabular overcoverage, CE greater than 40°, middle-aged females
- •Mixed = most common (80%), address both components
- •Crossover sign = focal acetabular retroversion
Traction Safety
- •Maximum 2 hours traction time
- •25-50lbs force typically needed
- •Minimum 6mm joint distraction
- •Break seal with IR before distraction
Nerves at Risk
- •Pudendal: perineal post (17% transient neurapraxia)
- •Lateral femoral cutaneous: anterolateral portal (meralgia)
- •Sciatic: excessive traction, posterior portals
- •Superior gluteal: proximal portal placement
Portal Placement
- •Anterolateral: 1cm anterior/superior to GT tip (viewing)
- •Anterior: ASIS horizontal meets GT vertical (working)
- •Posterolateral: 1cm posterior/superior to GT
- •Always establish under fluoroscopic guidance
Key Numbers
- •Alpha angle: greater than 55° = cam
- •CE angle: greater than 40° = pincer
- •Joint space: less than 2mm = poor outcome
- •2 hours max traction, 25lbs min force, 6mm distraction
Exam Pearls
- •FADIR test most sensitive for FAI
- •Joint space greater than 2mm critical for good outcomes
- •Labral repair preferred over debridement
- •Pudendal nerve most commonly injured