TOTAL HIP ARTHROPLASTY INDICATIONS
Patient Selection | Pain and Disability | Failed Conservative Treatment | Quality of Life
PRIMARY INDICATIONS
Critical Must-Knows
- Pain and disability refractory to conservative management is the primary indication
- Radiographic severity alone does not determine need for THA - symptoms drive decision
- 6 months of conservative treatment (physio, analgesia, weight loss) should be trialled first
- Active infection is an absolute contraindication - must be eradicated first
- AOANJRR data shows 95% survivorship at 15 years for modern THA implants in Australia
Examiner's Pearls
- "Indication = pain + disability + radiographic OA + failed conservative Rx
- "Beware young patients (under 50) - higher revision burden, consider alternatives
- "AVN: Stage III-IV (collapse) = THA. Stage I-II = consider hip preservation
- "DDH patients need preoperative templating and may require specialized implants
Critical THA Indication Exam Points
Indication Triad
Pain + Disability + Failed Conservative. THA requires all three: (1) significant pain affecting quality of life, (2) functional disability, (3) adequate trial of non-operative management. Radiographic severity alone is not an indication.
Age Considerations
50-80 years is optimal. Younger patients (under 50) have higher lifetime revision risk and may benefit from hip preservation surgery. Older patients (over 80) have higher perioperative risk but excellent implant survival if they survive surgery.
Contraindications
Active infection is absolute. Relative contraindications include: active medical comorbidities, poor bone stock, neuromuscular disease affecting function, patient unable to comply with rehabilitation, ongoing substance abuse.
Australian Context
AOANJRR data mandatory. Know: (1) Over 50,000 THAs/year in Australia, (2) 95% survivorship at 15 years, (3) cemented femoral stems best in older patients, (4) bearing surface choice affects longevity. Quote registry data in viva.
Quick Decision Guide - THA vs Alternatives
| Patient Profile | Pathology | Treatment | Key Pearl |
|---|---|---|---|
| Young (Under 40), active | Early OA, mild AVN (Ficat I-II) | Hip preservation (osteotomy, arthroscopy) | Delay THA as long as possible - lifetime revision burden |
| Middle-aged (50-65), moderate activity | Symptomatic OA, failed conservative | Primary THA (uncemented or hybrid) | Optimal age group - balance of activity and longevity |
| Elderly (Over 75), low demand | Symptomatic OA or fractured NOF | Primary THA (cemented femoral stem) | AOANJRR: cemented stems superior in over 75s |
| Any age | AVN Stage III-IV with collapse | THA (consider dual mobility if young) | Core decompression fails after collapse occurs |
| DDH patient | Dysplastic acetabulum, high hip center | THA with specialized planning | Preoperative templating essential, may need structural graft |
PAINTHA INDICATIONS - PAIN Framework
Memory Hook:PAIN = the patient needs to have PAIN that has failed conservative management
ACTIVECONTRAINDICATIONS - ACTIVE Framework
Memory Hook:ACTIVE contraindications must be addressed before proceeding with surgery
MEDICALPREOPERATIVE ASSESSMENT - MEDICAL Framework
Memory Hook:MEDICAL workup ensures patient is optimized and surgical plan is clear
REGISTRYAOANJRR KEY DATA - REGISTRY Framework
Memory Hook:REGISTRY data from AOANJRR is essential exam knowledge for Australian practice
Overview and Epidemiology
Total hip arthroplasty (THA) is one of the most successful surgical procedures in modern medicine. The primary indication for THA is end-stage hip arthritis causing pain and disability that has failed conservative management.
Historical perspective:
- Sir John Charnley pioneered modern THA in the 1960s with the low-friction arthroplasty concept
- Cemented metal-on-polyethylene became the gold standard
- Evolution to modular implants, improved bearing surfaces, and minimally invasive techniques
- Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) established 1999 - world-leading registry
Why THA is Successful
THA works because it: (1) reliably eliminates pain from arthritic hip, (2) restores function and mobility, (3) has predictable long-term outcomes with modern implants (95% survival at 15 years), (4) significantly improves quality of life. The key is patient selection - matching the right patient to the right procedure at the right time.
Epidemiology in Australia (AOANJRR 2023 data):
Procedure Volume
- Over 50,000 primary THAs performed annually in Australia
- Increasing trend due to aging population
- Bilateral THA common (10-15% of patients eventually need contralateral)
- Male:Female ratio approximately 1:1.2 (OA slightly more common in women)
Primary Diagnoses
- Osteoarthritis: 85-90% (primary or secondary)
- Avascular necrosis: 5-10%
- Inflammatory arthritis: 2-5% (RA, AS)
- Fracture sequelae: 2-3%
- DDH and other: 1-2%
Anatomy and Pathophysiology of Hip Arthritis
Normal hip joint anatomy:
- Ball-and-socket joint with excellent stability and range of motion
- Femoral head (2/3 sphere) articulates with acetabulum (horseshoe-shaped lunate surface)
- Articular cartilage 2-4mm thick, allows load distribution and low-friction movement
- Labrum deepens socket and creates suction seal
- Capsule reinforced by ligaments (iliofemoral, pubofemoral, ischiofemoral)
Pathophysiology of osteoarthritis:
OA Progression is Variable
Osteoarthritis is not just "wear and tear". It is an active disease process involving: (1) cartilage degradation (matrix metalloproteinases), (2) subchondral bone changes (sclerosis, cysts), (3) synovial inflammation, (4) osteophyte formation. The rate of progression is highly variable - some patients plateau, others progress rapidly.
Radiographic changes:
| Stage | Findings | Symptoms | Management |
|---|---|---|---|
| Mild OA | Joint space narrowing, early osteophytes | Mild pain with activity | Conservative: weight loss, physio, analgesia |
| Moderate OA | Definite JSN, osteophytes, sclerosis | Pain limiting activity, stiffness | Consider injection, continue conservative |
| Severe OA | Bone-on-bone, large osteophytes, cysts | Constant pain, night pain, major disability | THA if conservative failed for 6+ months |
Symptom-Radiograph Mismatch
Critical concept: Radiographic severity does NOT always correlate with symptoms. Some patients have severe radiographic OA but minimal symptoms (do NOT offer surgery). Conversely, some have moderate radiographic changes but severe symptoms (may benefit from THA). Symptoms drive the decision, not X-rays alone.
Classification Systems
Tonnis Classification of Hip Osteoarthritis
Tonnis Grading of Hip Osteoarthritis
| Grade | Radiographic Features | Clinical Correlation |
|---|---|---|
| 0 | Normal | No OA |
| 1 | Sclerosis, mild JSN, osteophytes | Mild symptoms, conservative Rx |
| 2 | Moderate JSN, cysts | Moderate symptoms, consider injection |
| 3 | Severe JSN or bone-on-bone | Severe symptoms, THA if conservative failed |
Tonnis Grade 3 is the most common indication for THA when combined with failed conservative treatment.
Clinical Assessment
History and physical examination for THA candidacy:
History:
- Pain characteristics: Location (groin vs lateral), severity, progression
- Functional limitation: Walking distance, stairs, ADLs, sleep disturbance
- Previous treatments: Physio, injections, medications, duration and response
- Medical comorbidities: Cardiac, pulmonary, diabetes, immunosuppression
- Patient goals: Expectations for pain relief, function, activity level
Physical examination:
- Gait: Antalgic, Trendelenburg (abductor weakness), leg length discrepancy
- ROM: Flexion, extension, abduction, adduction, internal/external rotation (IR lost first in OA)
- Leg length: Measure true vs apparent LLD (ASIS to medial malleolus)
- Neurovascular: Femoral/dorsalis pedis pulses, sensation, motor function
- Associated pathology: Spine (flexion deformity), knee (referred pain pattern)
Patient-reported outcome measures:
- Oxford Hip Score (0-48, under 30 indicates severe impairment)
- WOMAC (Western Ontario and McMaster Universities Arthritis Index)
- HOOS (Hip disability and Osteoarthritis Outcome Score)
- SF-36 (quality of life measure)
Investigations
Imaging studies:
Plain radiographs (essential):
- AP pelvis (standing, weight-bearing, both hips visible)
- Lateral hip (cross-table or frog-leg)
- Findings: Joint space narrowing, osteophytes, sclerosis, cysts
- Measurement: Hip center, leg length, offset
Advanced imaging (selective):
- MRI: Early AVN detection (Stage I), soft tissue pathology, occult fracture
- CT scan: DDH planning, post-traumatic deformity, bone stock assessment
- Nuclear medicine: Bone scan for infection vs loosening differentiation (rare preoperative)
Laboratory investigations:
- FBC: Anemia (may need preoperative iron/EPO)
- UEC: Renal function for NSAID use, perioperative hydration
- HbA1c: If diabetic (target under 8%)
- ESR/CRP: Elevated suggests infection (investigate before elective THA)
- Coagulation studies: If on anticoagulation
Special investigations:
- ECG: All patients over 50 or with cardiac history
- Echocardiogram: If cardiac symptoms or murmur
- Pulmonary function tests: If severe COPD
- Urinalysis: Rule out UTI before elective surgery
Indications for Total Hip Arthroplasty
Primary indication: End-stage hip arthritis causing pain and functional disability that has failed adequate conservative management.
The Three Pillars of THA Indication:
-
Pain and Disability
- Pain that affects quality of life (sleep, ADLs, recreation)
- Functional limitation (walking distance, stairs, getting out of chair)
- Patient-reported outcome measures (HOOS, WOMAC, Oxford Hip Score) document severity
-
Radiographic Evidence
- Plain radiographs show joint space loss, osteophytes, sclerosis, cysts
- Confirms diagnosis but does NOT alone indicate need for surgery
- Severity on X-ray does not correlate perfectly with symptoms
-
Failed Conservative Treatment
- At least 6 months of appropriate non-operative management
- Includes: physiotherapy, weight loss, activity modification, analgesia (NSAIDs, paracetamol), intra-articular injection
- Patient compliance with conservative measures documented
Absolute Indications
- Severe OA with pain, disability, failed conservative (most common)
- AVN Stage III-IV with collapse and secondary OA
- Failed previous surgery (ORIF for fracture, osteotomy) with persistent pain
- Acute femoral neck fracture in elderly (hemiarthroplasty vs THA decision)
Relative Indications
- Young patient (under 50) with severe symptoms - weigh alternatives
- Inflammatory arthritis (RA, AS) with hip involvement
- Post-traumatic arthritis after acetabular fracture, dislocation
- DDH with secondary arthritis
- Failed hip preservation (PAO, femoral osteotomy)
Specific diagnostic categories:
Primary Osteoarthritis
Most common indication (85-90% of THAs)
Presentation:
- Insidious onset of groin pain, may radiate to thigh/knee
- Mechanical pain (worse with activity, better with rest)
- Progressive stiffness (especially internal rotation lost first)
- Gait changes (antalgic, Trendelenburg if abductors weak)
Radiographic criteria:
- Joint space narrowing (weight-bearing AP pelvis)
- Osteophyte formation (femoral and acetabular)
- Subchondral sclerosis
- Subchondral cysts (geodes)
When to offer THA:
- Patient reports pain affecting sleep or ADLs
- Walking distance limited (typically under 500m)
- Failed 6 months of conservative treatment
- Patient motivated for surgery and rehabilitation
- Medical comorbidities optimized
Primary vs Secondary OA
Primary OA = idiopathic, typically over 50 years, no clear cause. Secondary OA = identifiable cause such as DDH, AVN, SCFE, Perthes, post-traumatic. Important to distinguish because secondary OA may require specialized surgical planning (e.g., DDH needs high hip center restoration).
Contraindications to Total Hip Arthroplasty
Absolute vs Relative Contraindications
| Contraindication | Category | Management |
|---|---|---|
| Active sepsis (local or systemic) | Absolute | Eradicate infection first, stage reconstruction |
| Active osteomyelitis femur/pelvis | Absolute | Treat infection, may need long-term suppression before THA |
| Recent MI (under 6 months) | Absolute | Defer until cardiac clearance and optimization |
| Severe uncontrolled medical comorbidity | Absolute | CHF, COPD exacerbation, uncontrolled DM - optimize first |
| Patient unable/unwilling to comply with rehabilitation | Absolute | Cognitive impairment, psychiatric illness precluding participation |
| Age under 50 years | Relative | Consider alternatives (osteotomy, resurfacing, delay THA if possible) |
| Severe obesity (BMI over 40) | Relative | Higher complication risk - consider weight loss program first |
| Active substance abuse | Relative | Higher infection risk, poor compliance - address before surgery |
| Severe osteoporosis, poor bone stock | Relative | May need specialized techniques (impaction grafting, long stems) |
| Peripheral vascular disease | Relative | Assess wound healing potential, vascular surgery input |
| Neuromuscular disease (Parkinson, CVA) | Relative | Higher dislocation risk - consider constrained liner, dual mobility |
Infection: Absolute Contraindication
Active infection anywhere in the body is an absolute contraindication to elective THA. This includes: (1) local hip infection (previous septic arthritis), (2) distant infection (UTI, dental abscess, skin infection), (3) bacteremia. Why: Risk of hematogenous seeding to prosthetic joint. Management: Eradicate infection first, minimum 6 weeks antibiotics, inflammatory markers normal before proceeding.
Special contraindication scenarios:
Young Patients (Under 50)
Not absolute contraindication but need careful discussion:
- Lifetime revision risk high (50-year-old may need 2-3 revisions in lifetime)
- Activity level typically higher (increased wear, loosening risk)
- Alternatives: Hip arthroscopy, PAO, femoral osteotomy, resurfacing
- If THA necessary: hard-on-hard bearings (ceramic-on-ceramic), dual mobility
- Counsel: Revision likely, activity restrictions, long-term implications
Neuromuscular Disease
High dislocation risk:
- Parkinson's disease (rigidity, bradykinesia, falls)
- CVA with spasticity, weakness
- Cerebral palsy, muscular dystrophy
- Mitigation strategies: Dual mobility bearing, constrained liner, large diameter heads
- Patient and family education about dislocation precautions
- Consider if benefits outweigh risks (severe pain, immobility)
Patient Selection and Preoperative Assessment
Patient selection is the single most important determinant of THA outcome.
Ideal THA candidate:
- Age 50-80 years (optimal risk-benefit balance)
- Severe symptomatic hip arthritis (pain, disability)
- Failed adequate conservative trial (6+ months)
- Motivated patient with realistic expectations
- Able to participate in rehabilitation
- Medical comorbidities optimized
- Social support for postoperative period
Preoperative assessment:
Preoperative Workup
- History: Pain severity, functional limitation, previous treatments, medical history
- Examination: Hip ROM, leg length, gait, neurovascular, spine (fixed deformity)
- Imaging: AP pelvis, lateral hip, assess arthritis severity
- Discussion: Diagnosis, natural history, treatment options (conservative vs surgical)
- Confirm failed conservative treatment (6 months minimum)
- Patient-reported outcomes (HOOS, Oxford Hip Score) document severity
- Medical clearance: Cardiac risk assessment (RCRI), pulmonary function if indicated
- Dental clearance: Rule out infection source
- MRSA screening: Nasal swab, decolonization protocol if positive
- Templating: AP pelvis with magnification marker, template component sizes
- Consent: Risks (infection 0.5-1%, dislocation 2-3%, DVT 1-2%, revision 5% at 15 years), benefits, alternatives
- Discuss: Approach (anterior, posterior, lateral), bearing surface, fixation method
- Preoperative education: DVT prophylaxis, mobility restrictions, rehabilitation expectations
Medical optimization:
Cardiac
- RCRI score: Revised Cardiac Risk Index (6 predictors)
- High risk: Recent MI, CHF, CVA, DM, renal insufficiency, high-risk surgery
- Cardiology referral if RCRI greater than or equal to 2
- Beta-blockers, statins perioperatively
- Consider stress test if symptomatic
Pulmonary
- COPD: Optimize bronchodilators, stop smoking
- OSA: CPAP compliance, perioperative monitoring
- Respiratory infection: Defer surgery until resolved
- ABG/PFTs if severe disease
Metabolic
- Diabetes: HbA1c under 7% ideal, under 8% acceptable
- Poor control increases infection risk 3-fold
- Anemia: Iron studies, EPO if Hb under 110 g/L
- Renal: Adjust medications, hydration protocol
HbA1c Threshold
HbA1c over 8% is associated with significantly higher risk of surgical site infection, wound dehiscence, and periprosthetic joint infection. Guidelines: Ideally HbA1c under 7% before elective THA. If 7-8%, counsel about higher risk. If over 8%, strongly consider delaying surgery for 3 months of glycemic optimization. Emergency surgery (fracture) - proceed with heightened vigilance.
Dental clearance:
Recent dental infection or poor dentition can lead to bacteremia and hematogenous seeding of prosthetic joint.
Protocol:
- All patients: Dental examination within 6 months of THA
- Active dental infection: Treat first, wait 6 weeks minimum
- Poor dentition, multiple caries: Consider extraction and healing before THA
- Routine dental prophylaxis: Per ADA guidelines (not routinely recommended for most patients, consider high-risk)
MRSA screening and decolonization:
MRSA Protocol
Nasal swab for MRSA colonization (PCR test, results in 24-48 hours)
Decolonization protocol:
- Mupirocin nasal ointment (TID for 5 days)
- Chlorhexidine body wash (daily for 5 days)
- Reswab to confirm eradication
If MRSA positive history: Vancomycin instead of cefazolin for prophylaxis
Preoperative Planning and Templating
Templating is essential for:
- Component size prediction (reduces operative time, inventory needs)
- Leg length restoration planning
- Offset restoration (abductor moment arm)
- Identifying anatomical challenges (DDH, previous surgery, deformity)
Required radiographs:
AP Pelvis
- Standing, weight-bearing
- Both hips visible, coccyx centered
- Magnification marker (ball bearing of known size, typically 25mm or 30mm, at level of greater trochanter)
- Pelvis level (obturator foramina symmetric)
- Use to template acetabular component size and position
Lateral Hip
- Cross-table lateral or frog-leg lateral
- Assess femoral offset, canal shape
- Identify deformity (previous fracture, Paget's)
- Template femoral component size, neck cut level
Digital templating process:
Templating Steps
Measure magnification marker on X-ray, input into software to calibrate (typically 110-120% magnification)
- Mark hip center of rotation (COX point at intersection of lines)
- Mark teardrop (medial acetabular wall landmark)
- Mark lesser trochanter
- Measure preoperative leg length (from COX to ischial tuberosity or iliac crest)
- Place cup at anatomic hip center (teardrop plus 5mm medial, 25mm superior to teardrop)
- Template covers subchondral bone, avoids protrusio or overmedialization
- Note size (typically 50-58mm in adults)
- Plan inclination (40-45 degrees) and anteversion (15-20 degrees)
- Place stem in canal, fill metaphysis (press-fit) or 2mm gap (cemented)
- Match native offset (distance from center of head to center of femoral canal)
- Select neck length to restore leg length
- Note stem size (typically 10-14 for uncemented, 2-4 for cemented)
- Measure templated leg length (COX to ischial tuberosity)
- Goal: Restore native length or up to 1cm lengthening if needed for stability
- Over-lengthening (more than 1.5cm) risks nerve palsy, patient dissatisfaction
- Document planned leg length to inform intraoperative measurement
Offset restoration:
Offset vs Leg Length
Offset (distance from center of rotation to greater trochanter) affects abductor moment arm. Leg length affects limb length equality. They are independent but related. You can have: (1) normal offset, short leg (head too small), (2) normal offset, long leg (head too large), (3) increased offset, normal leg (lateral cup position). Goal: Restore both offset and leg length to within 5mm of native or contralateral side.
Special considerations:
- DDH: High hip center, small canal, increased anteversion - may need structural graft, specialized implants
- AVN in young patient: Consider resurfacing vs THA, templating for both
- Previous surgery: Retained hardware, altered anatomy - plan hardware removal approach
- Leg length discrepancy: Preoperative LLD may be longstanding, patient adapted - discuss postoperative expectations
Alternatives and Hip Preservation
Before proceeding with THA in younger patients, consider alternatives:
Hip Preservation vs THA
| Procedure | Indication | Age Group | Outcome |
|---|---|---|---|
| Hip arthroscopy | FAI, labral tear, early OA | Under 50 | Good short-term pain relief, may delay THA 5-10 years |
| Periacetabular osteotomy (PAO) | Symptomatic DDH, no significant OA | 20-40 | Good outcomes, delays/prevents THA in 70% at 10 years |
| Femoral osteotomy | Cam FAI, femoral head AVN (pre-collapse) | Under 50 | Variable, may delay THA |
| Core decompression | AVN Stage I-II (pre-collapse) | Any age | May halt progression, does not work after collapse |
| Hip resurfacing | Young male, large femoral head, no cysts | Under 60 | Metal-on-metal concerns, AOANJRR shows higher revision than THA |
When to Refer for Hip Preservation
Refer to hip preservation surgeon if: (1) Patient under 50 years, (2) Radiographic OA mild to moderate (joint space preserved), (3) Identifiable pathoanatomy (FAI, dysplasia), (4) Patient motivated for complex rehab. Don't refer if: Severe OA (Tonnis Grade 3), AVN with collapse, patient wants definitive solution (THA provides better pain relief than osteotomy in end-stage disease).
Hip resurfacing:
Once popular in young males, now declining in use due to:
- Metal-on-metal bearing concerns (pseudotumor, metallosis, ARMD)
- AOANJRR data shows higher revision rate than THA (especially in women)
- Requires large femoral head (over 50mm), good bone quality
- Contraindicated: Renal impairment, metal allergy, osteoporosis, cysts
Still considered in: Young male athlete, very large femoral head, strong bone, patient counseled about risks
Management Algorithm
THA Decision Pathway:
Initial Conservative Management
All patients with hip OA should undergo trial of conservative treatment before THA:
Conservative Treatment Progression
- Education: Natural history, activity modification, weight loss
- Physiotherapy: Strengthen hip abductors, core, improve gait
- Analgesia: Paracetamol, topical NSAIDs, oral NSAIDs (if tolerated)
- Adjuncts: Walking aids (cane in opposite hand), heat/ice
- Intra-articular injection: Corticosteroid (triamcinolone 40mg)
- Duration of relief: Variable (50% get 3-6 months relief)
- PRP, hyaluronic acid: Evidence limited, not PBS-funded in Australia
- Modify activities: Avoid high-impact, aggravating movements
If symptoms persist despite compliance with conservative measures → Consider THA
Criteria for surgical referral:
- Pain affecting sleep or ADLs
- Limited walking distance (under 500m)
- Patient-reported outcomes (Oxford Hip Score under 30/48)
- Patient understands risks/benefits and motivated
Duration of Conservative Trial
6 months is the generally accepted minimum duration of conservative treatment before THA. However, this is a guideline, not absolute rule. Exceptions: (1) Rapidly progressive painful AVN with collapse (may operate sooner), (2) Acute fracture in elderly (immediate surgery), (3) Patient tried conservative for years before presenting (don't need another 6 months). Use clinical judgment.
Surgical Technique Overview
Surgical Approaches for THA
| Approach | Internervous Plane | Key Features |
|---|---|---|
| Posterior (Moore/Southern) | Gluteus maximus (inferior gluteal) / Short external rotators (nerve to QF) | Most common, excellent femoral exposure |
| Anterior (Smith-Petersen) | TFL (superior gluteal) / Sartorius (femoral) | Tissue-sparing, steep learning curve |
| Direct Lateral (Hardinge) | Splits gluteus medius | Stable, abductor damage risk |
Complications
Complications of THA that patients must understand before consenting:
Major Complications of THA
| Complication | Incidence | Prevention Strategies | Impact on Decision |
|---|---|---|---|
| Periprosthetic joint infection | 0.5-1.0% (AOANJRR) | Antibiotic prophylaxis, MRSA screening, minimize operative time | Devastating complication requiring staged revision, prolonged antibiotics |
| Dislocation | 2-3% (higher posterior approach, neuromuscular disease) | Large diameter heads, dual mobility, optimal component positioning | Most dislocations occur in first 3 months. May need revision if recurrent |
| DVT/PE | 1-2% symptomatic DVT, 0.1-0.4% fatal PE | Chemoprophylaxis (LMWH, apixaban), early mobilization, compression stockings | Major cause of perioperative mortality. Prophylaxis mandatory |
| Nerve injury | 0.5-2% (sciatic most common) | Avoid limb lengthening over 4cm, careful retractor placement | Femoral nerve (anterior), sciatic (posterior/lateral). Most resolve but may be permanent |
| Vascular injury | 0.1-0.3% | Careful cement pressurization, avoid excessive acetabular reaming medially | External iliac vessels at risk with anterior approach, obturator with reaming |
| Leg length discrepancy | 10-15% (over 1cm) | Preoperative templating, intraoperative measurement, trial reduction | Most common cause of patient dissatisfaction. Discuss preoperative LLD |
| Aseptic loosening (revision) | 5% at 15 years (AOANJRR) | Good fixation technique, optimal implant choice, patient activity modification | May require revision. Modern implants have excellent longevity |
| Periprosthetic fracture | 1-2% intraoperative, 1-2% postoperative | Gentle technique, avoid varus malalignment, press-fit technique | May need revision or ORIF depending on timing and stability |
Consent Discussion
When consenting for THA, must discuss: (1) Benefits - pain relief (90-95% success), improved function, better quality of life. (2) Risks - infection (1%), dislocation (2-3%), DVT/PE (1-2%), nerve injury (1-2%), revision (5% at 15 years), leg length inequality (10%), ongoing pain (5-10%). (3) Alternatives - conservative, hip preservation, other arthroplasty options. (4) Specific to patient - age-related revision risk, comorbidity risks.
Postoperative Care
Immediate postoperative management:
Postoperative Protocol
- Pain control: Multimodal analgesia (regional block, IV paracetamol, opioids as needed)
- DVT prophylaxis: LMWH or apixaban (start 6-12 hours post-op)
- Mobilization: Sit out of bed Day 0, walk with physio Day 1
- Precautions: Approach-specific (posterior = no flexion over 90°, adduction, IR)
- Progressive mobilization with walking aids
- Stair practice
- Discharge planning (home setup, support)
- Wound inspection
- Wound review, suture/staple removal
- Progress mobility, reduce walking aids
- Continue DVT prophylaxis (6 weeks total)
- Hip precautions education reinforcement
- Clinical review, X-ray (AP pelvis)
- Assess healing, component position, no subsidence
- Progress to full weight-bearing, discard aids if able
- Return to driving (if safe, right hip, off opioids)
- Return to work (desk 6 weeks, manual 3 months)
- Return to low-impact sports (swimming, cycling, golf)
- Avoid high-impact (running, jumping sports)
- Clinical examination, X-ray
- PROMs (Oxford Hip Score, satisfaction)
- Long-term surveillance plan (yearly first 5 years, then as needed)
Hip precautions (approach-dependent):
- Posterior approach: No flexion over 90°, no adduction past midline, no internal rotation (6-12 weeks)
- Anterior approach: No extension, external rotation, or adduction (6 weeks)
- Lateral approach: Minimal restrictions, avoid extreme abduction initially
Outcomes and Prognosis
Expected outcomes of THA:
Pain relief:
- 90-95% of patients report significant pain improvement
- Most patients pain-free or minimal pain at rest and activity
- Night pain typically completely resolved
- Groin pain may persist in 5-10% (unexplained, may be from spine or soft tissues)
Functional improvement:
- Walking distance increases dramatically (unlimited in most patients)
- Stair climbing normalized
- ADLs (dressing, bathing, shoe tying) significantly easier
- Return to work: 80-90% return to previous work level
- Return to sport: Low-impact sports encouraged, high-impact discouraged
Patient satisfaction:
- 85-90% "very satisfied" with THA outcome
- 5-10% "satisfied with reservations" (ongoing pain, stiffness, LLD)
- Less than 5% "dissatisfied" (persistent pain, complications, unmet expectations)
Implant survival (AOANJRR data):
- 5 years: 97% survival
- 10 years: 95% survival
- 15 years: 93-95% survival (modern implants)
- 25 years: 85-90% survival (projected)
Factors affecting outcome:
| Factor | Impact on Outcome | Mitigation |
|---|---|---|
| Young age (under 50) | Higher lifetime revision risk | Counsel about revision burden, activity modification |
| Obesity (BMI over 35) | Higher infection, dislocation risk | Weight loss preoperatively, vigilant wound care |
| Diabetes (HbA1c over 8%) | Higher infection risk | Glycemic optimization before surgery |
| Neuromuscular disease | Higher dislocation risk | Dual mobility bearing, constrained liner |
| Surgeon experience | Better outcomes with high-volume surgeons | Refer complex cases to experienced surgeon |
Long-term surveillance:
- Annual clinical review first 5 years
- X-rays at 1 year, then every 2-3 years
- Monitor for: pain (loosening, infection), wear, osteolysis
- AOANJRR tracks all Australian THAs for long-term outcomes
Evidence Base and Key Studies
AOANJRR Annual Report 2023
- Over 50,000 primary total hip arthroplasties performed annually in Australia
- 95% cumulative percent revision at 15 years for primary THA (modern implants)
- Cemented femoral stems have lower revision rate than uncemented in patients over 75 years
- Ceramic-on-polyethylene and ceramic-on-ceramic bearings show excellent long-term survival
- Metal-on-metal hip resurfacing has higher revision rate compared to THA, especially in women
Conservative vs Surgical Management of Hip OA (AAOS Guidelines)
- Strong recommendation for patient education and self-management
- Moderate recommendation for physiotherapy, weight loss, and NSAIDs
- Limited evidence for intra-articular corticosteroid injections (short-term benefit)
- Inconclusive evidence for PRP, hyaluronic acid, or prolotherapy
- THA recommended when conservative measures fail and symptoms are severe
HbA1c and Infection Risk in THA
- Cohort study of 5000+ THA patients analyzing HbA1c and infection outcomes
- HbA1c over 7% associated with 2-fold increased risk of superficial SSI
- HbA1c over 8% associated with 3-fold increased risk of deep infection requiring revision
- Effect independent of diabetes diagnosis - reflects glycemic control
- Optimizing HbA1c preoperatively may reduce infection risk
Young Patient Outcomes and Revision Burden
- Cohort study of over 600 patients under 50 years at time of primary THA
- 20-year cumulative revision rate: 25% for patients under 40, 15% for ages 40-50
- Main indications for revision: aseptic loosening (60%), instability (20%), infection (10%)
- Patient activity level and BMI were significant predictors of revision
- Despite high revision rate, most patients satisfied with decision to proceed with THA
THA vs Hip Resurfacing (AOANJRR Comparison)
- Hip resurfacing has higher cumulative revision rate than THA at 10 years (8.7% vs 4.9%)
- Revision rate for resurfacing highest in women and older patients
- Main indications for resurfacing revision: fracture (40%), loosening (30%), metal-related complications (20%)
- THA provides more predictable long-term outcomes across all patient groups
- Resurfacing use declining in Australia since 2012
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Middle-Aged Patient with OA
"A 58-year-old female presents with right hip pain for 3 years. Pain is in the groin, worse with walking, limits her to 200 meters. She has tried physiotherapy and takes paracetamol regularly. X-ray shows severe OA with joint space loss and osteophytes. Her contralateral hip is normal. She asks about hip replacement. What is your assessment and management?"
Scenario 2: Young Patient with AVN
"A 35-year-old male presents with right hip pain for 6 months. He has a history of steroid use for asthma. X-ray shows collapse of the femoral head consistent with Stage III AVN. MRI shows early changes in the contralateral hip (Stage I). He is a keen footballer and works as a carpenter. He asks about his treatment options. How do you counsel him?"
Scenario 3: Diabetic Patient with HbA1c 9.2%
"A 62-year-old male with severe hip OA is scheduled for THA in 2 weeks. His preoperative workup reveals HbA1c of 9.2%. He is on oral hypoglycemics and has been poorly controlled for several years. He is very keen to proceed as he is in significant pain. How do you manage this?"
MCQ Practice Points
Indication Criteria Question
Q: What are the three essential components of the indication for total hip arthroplasty? A: (1) Pain and functional disability affecting quality of life, (2) Radiographic evidence of advanced osteoarthritis, (3) Failed conservative treatment for at least 6 months (physio, analgesia, weight loss, activity modification). All three must be present - radiographic severity alone is not an indication.
AOANJRR Data Question
Q: What is the cumulative percent revision rate for primary THA at 15 years according to AOANJRR data? A: 5%, meaning 95% survivorship at 15 years for modern THA implants. This is one of the most successful surgical procedures. Key additional AOANJRR findings: (1) Over 50,000 THAs performed annually in Australia, (2) Cemented femoral stems have lower revision rate in patients over 75 years, (3) Metal-on-metal hip resurfacing has higher revision rate than THA.
Contraindication Question
Q: What is the absolute contraindication to elective total hip arthroplasty? A: Active infection (local or systemic) is an absolute contraindication. This includes active hip infection (previous septic arthritis), distant infection (UTI, dental abscess), or bacteremia. Infection must be eradicated (minimum 6 weeks antibiotics, inflammatory markers normal) before proceeding with elective THA. Risk of hematogenous seeding to prosthetic joint is too high.
Young Patient Question
Q: What is the lifetime revision burden for a 40-year-old patient undergoing THA? A: High - studies show approximately 25% revision rate by 20 years in patients under 40. This means the patient may need 2-3 revisions over their lifetime. Main indications for revision: aseptic loosening (60%), instability (20%), infection (10%). Important to counsel young patients about this risk and consider hip preservation alternatives when possible.
HbA1c Threshold Question
Q: What HbA1c level is associated with significantly increased infection risk in THA, and what is the recommended management? A: HbA1c over 8% is associated with 3-fold increased risk of deep periprosthetic joint infection. Management: Postpone elective THA for 3 months of glycemic optimization with goal HbA1c under 8% (ideally under 7%). Refer to endocrinology, recheck HbA1c at 8-10 weeks. This is a modifiable risk factor - optimization reduces infection risk.
AVN Staging Question
Q: At what stage of avascular necrosis is THA indicated, and why? A: THA is indicated at Stage III-IV (Ficat classification): Stage III = subchondral collapse (crescent sign), Stage IV = secondary acetabular arthritis. Why: Once collapse occurs, hip preservation (core decompression) is no longer effective. THA provides reliable pain relief and restoration of function. Stage I-II (pre-collapse) can be managed with hip preservation techniques.
Australian Context and Medicolegal Considerations
AOANJRR Data
Essential exam knowledge:
- Over 50,000 primary THAs annually in Australia
- 95% survivorship at 15 years (modern implants)
- Cemented femoral stems superior in patients over 75 years
- Metal-on-metal resurfacing has higher revision rate than THA
- Ceramic-on-polyethylene excellent long-term outcomes
- Data guides evidence-based implant selection
PBS and Medicare
Australian healthcare system:
- THA covered by Medicare (public system) with waiting times
- Private health insurance covers elective THA with surgeon choice
- PBS-funded medications: analgesia, DVT prophylaxis
- Prostheses List regulates implant costs
- THA procedures fully covered under public system
Medicolegal Considerations
Key documentation requirements:
- Informed consent: Document discussion of risks (infection, dislocation, DVT, revision), benefits (pain relief, function), alternatives (conservative, other surgery)
- Failed conservative: Document duration and compliance with non-operative treatment (minimum 6 months typically)
- Medical optimization: HbA1c if diabetic, cardiac clearance if indicated, MRSA screening
- Preoperative planning: Templating documented, leg length plan documented
- Complications disclosure: Specific percentages (infection 1%, dislocation 2-3%, revision 5% at 15 years)
- Patient expectations: Realistic goals discussed (pain relief yes, perfect hip no), activity restrictions
- Young patients: Lifetime revision burden explicitly discussed and documented
Common litigation issues:
- Leg length discrepancy (most common cause of dissatisfaction) - document preoperative LLD and plan
- Infection (ensure optimization, prophylaxis, technique)
- Nerve palsy (avoid excessive lengthening, document neurovascular exam pre and post)
- Wrong level (confirm hip using imaging in OR)
Australian Hospital Systems
In viva, demonstrate understanding of Australian context: (1) Public system - THA covered by Medicare, waiting times vary by state (6-12 months typical), urgent cases prioritized, (2) Private system - faster access, surgeon choice, implant choice, (3) AOANJRR - world-leading registry guides implant selection, quote data in exam, (4) PBS - medications covered (NSAIDs, analgesia, DVT prophylaxis), (5) Prostheses List - regulates implant costs, influences surgeon choice.
TOTAL HIP ARTHROPLASTY INDICATIONS
High-Yield Exam Summary
Indication Triad
- •Pain + Disability (affecting quality of life, sleep, ADLs)
- •Radiographic OA (joint space loss, osteophytes, sclerosis)
- •Failed conservative Rx (6+ months: physio, analgesia, injection)
- •All three required - X-ray severity alone not an indication
Primary Diagnoses
- •Osteoarthritis (85-90%) - most common indication
- •AVN Stage III-IV (5-10%) - after collapse or secondary OA
- •Inflammatory arthritis (2-5%) - RA, AS with joint destruction
- •Post-traumatic (2-3%) - failed ORIF, fracture sequelae
- •DDH and other (1-2%) - requires specialized planning
Contraindications
- •ABSOLUTE: Active infection (local or systemic) - must eradicate first
- •RELATIVE: Age under 50 (high revision burden, consider alternatives)
- •RELATIVE: Severe obesity BMI over 40 (higher complications)
- •RELATIVE: Uncontrolled medical comorbidities (optimize first)
- •RELATIVE: Poor bone stock, neuromuscular disease (higher risk)
Age-Based Decision
- •Under 40: Exhaust hip preservation, counsel re: 25% revision at 20 years
- •50-65: Optimal age, uncemented/hybrid, excellent outcomes
- •Over 75: Cemented femoral stem (AOANJRR), medical optimization critical
- •Young = higher revision burden, Old = higher perioperative risk
Preoperative Workup
- •Medical: Cardiac risk (RCRI), HbA1c if diabetic (under 8% target), MRSA screen
- •Dental: Clearance within 6 months, treat active infection
- •Imaging: AP pelvis + lateral hip with magnification marker
- •Templating: Predict component sizes, plan leg length restoration
- •Consent: Infection 1%, dislocation 2-3%, DVT 1-2%, revision 5% at 15 years
AOANJRR Key Data
- •Over 50,000 primary THAs per year in Australia
- •95% survivorship at 15 years (5% cumulative revision rate)
- •Cemented femoral stems better in patients over 75 years
- •Metal-on-metal resurfacing higher revision rate than THA
- •Ceramic-on-polyethylene excellent long-term outcomes