Post-Traumatic Knee Arthritis
Post-Traumatic Knee Arthritis
Clinical Scenario
A 68-year-old woman presents with a 5-year history of progressively worsening left knee pain that has failed conservative management. She was involved in a motor vehicle accident 20 years ago and sustained a tibial plateau fracture that was treated with open reduction and internal fixation (ORIF). She now has difficulty walking more than 100 metres and has significant night pain affecting her sleep.
History:
- Left tibial plateau fracture (Schatzker VI) 20 years ago
- ORIF with dual plating at that time
- Hardware removed 18 months post-injury due to soft tissue irritation
- Gradually worsening knee pain over 5 years
- Now severe pain affecting sleep and daily activities
- Failed conservative treatment:
- Physiotherapy
- Weight loss (BMI now 32)
- NSAIDs (ceased due to gastric irritation)
- Intra-articular steroid injections x3 (last 6 months ago, temporary relief)
- No other joint problems
- Non-smoker, minimal alcohol
Medical History:
- Hypertension (well controlled)
- Type 2 Diabetes (HbA1c 7.2%)
- BMI 32
Examination Findings:
- Previous surgical scars: Anteromedial and anterolateral approaches
- Fixed flexion deformity 15°
- Further flexion to 100°
- Varus alignment in stance (~10°)
- Tender medial and lateral joint lines
- No effusion
- Stable to varus/valgus stress in extension
- Mild medial instability at 30° flexion
- Intact neurovascular examination
- No signs of infection
Investigations
Laboratory Results
Imaging
Weight-Bearing AP and Lateral X-rays:
- Severe tricompartmental osteoarthritis
- Previous hardware sites visible (healed screw holes)
- Medial and lateral tibial plateau depression
- Bone loss in medial tibial plateau
- 10° varus alignment on mechanical axis
- Kellgren-Lawrence Grade 4
Long-Leg Standing X-ray (Hip-Knee-Ankle):
- Mechanical axis varus 8°
- No extra-articular tibial deformity
- Previous fracture healed in acceptable alignment
- No residual hardware
CT Scan Left Knee:
- Confirms bone loss in posteromedial tibial plateau
- No retained hardware fragments
- No evidence of non-union
- Subchondral cyst formation medially
Questions & Model Answers
What are the specific challenges of total knee arthroplasty in a post-traumatic knee?
How do you approach pre-operative planning for this post-traumatic TKA?
Describe your surgical technique for TKA in this patient, addressing the bone loss and deformity.
What is the role of staged surgery in post-traumatic TKA? When would you consider it?
What are the expected outcomes and complications of TKA in post-traumatic arthritis?
How do you optimise this patient pre-operatively for TKA?
Key Teaching Points
| Concept | Detail |
|---|---|
| Pre-op Assessment | Rule out infection, assess bone loss, plan for constraint |
| Bone Loss | Metal augments, cones, sleeves for defects |
| Ligament Issues | CCK or hinged prosthesis if collaterals insufficient |
| Incision | Use most lateral previous incision |
| Staging | Consider if hardware in situ or infection concern |
| Outcomes | 85-90% 10-year survival (lower than primary TKA) |
Common Examiner Follow-up Questions
-
"What is the constraint ladder in TKA?"
- CR (cruciate retaining) - least constrained
- PS (posterior stabilised) - sacrifices PCL
- CCK (constrained condylar knee) - varus/valgus constraint
- Rotating hinge - sagittal and coronal constraint
- Fixed hinge - most constrained (rarely used)
-
"How do you address extra-articular deformity?"
- If <10°: can often correct with intra-articular cuts (shift tibial cut)
- If 10-20°: consider corrective osteotomy (can be simultaneous or staged)
- If >20°: staged corrective osteotomy then TKA
- Alternative: use revision-style implants with offset stems
-
"When would you use structural allograft vs metal augments?"
- Metal augments: Standard for most defects, modular, reliable
- Structural allograft: Massive defects, young patients, reconstruct bone stock
- Trend towards metal cones/sleeves for severe defects
- Allograft: risk of resorption, longer incorporation time