Active vs. Passive Treatment: A False Choice?
When you’re diagnosed with knee osteoarthritis, you’ll often hear two treatment recommendations: physical therapy and injections. Many patients think they need to choose between them.
The reality? These treatments work in completely different ways and often complement each other. Physical therapy addresses the underlying muscle weakness and movement patterns that worsen OA, while injections provide faster symptom relief to help you participate in PT.
Let’s look at when to use each—and why the best approach is often both, not either/or.
Side-by-Side Comparison
| Factor | Physical Therapy | Injections (Cortisone/HA) |
|---|---|---|
| How it works | Strengthens muscles, improves mechanics | Reduces inflammation or adds lubrication |
| Time to benefit | 4-8 weeks | 1-4 weeks |
| Active vs. passive | Active (you do the work) | Passive (done to you) |
| Addresses cause | Yes (weakness, mechanics) | No (symptoms only) |
| Duration of effect | Long-term if continued | Temporary (weeks-months) |
| Medicare coverage | Yes (typically 20-30 visits/year) | Yes (when medically necessary) |
| Typical copay | $20-50 per visit | $50-150 per injection |
| Typical course | 6-12 visits over 6-12 weeks | 1-5 injections (depends on type) |
| Success rate | 60-70% improve | 50-80% improve (varies by type) |
| Prevents worsening | Yes | No |
| Side effects | Muscle soreness, rare injury | Post-injection pain, infection risk |
| Long-term safety | Excellent | Good (with limits on cortisone) |
| Effort required | High (exercises 3-5×/week) | None |
Physical Therapy: Building Long-Term Resilience
What It Is
Physical therapy for knee OA is a structured program of exercises and education designed to strengthen the muscles around your knee, improve joint mechanics, and teach you how to move in ways that reduce stress on damaged cartilage.
How It Works
What a Typical PT Program Includes
Phase 1 (Weeks 1-2): Pain Management and Gentle Movement
- Manual therapy to reduce pain and stiffness
- Gentle range of motion exercises
- Ice/heat modalities
- Introduction to home exercises
Phase 2 (Weeks 3-6): Strengthening
- Progressive resistance exercises
- Quadriceps and hip strengthening focus
- Balance and proprioception training
- Functional movement practice
Phase 3 (Weeks 7-12): Functional Training and Independence
- Sport or activity-specific training
- Advanced strengthening
- Transition to home program
- Long-term maintenance plan
Advantages
Limitations
Injections: Fast-Acting Symptom Relief
Types of Injections
Cortisone (Corticosteroid) Injections:
- Powerful anti-inflammatory
- Fast relief (often 1-2 weeks)
- Duration: 6 weeks to 3 months
- Limited to 3-4 per year due to potential cartilage damage
Hyaluronic Acid (HA) Injections:
- Adds lubrication and cushioning
- Slower relief (2-4 weeks)
- Duration: Up to 6 months
- Can be repeated as needed
How They Work
Advantages
Limitations
What Does the Evidence Say?
Physical Therapy Evidence
Multiple high-quality studies and systematic reviews show:
Strong Evidence For:
- Pain reduction equivalent to NSAIDs and comparable to injections
- Functional improvement in walking, stairs, daily activities
- Long-term benefits lasting 6-12+ months after completing program
- Delayed need for surgery in many patients
- Cost-effectiveness compared to surgery and long-term medication use
Best Outcomes When:
- Supervised by skilled physical therapist
- Exercises done consistently (3-5×/week)
- Program includes both strengthening and functional training
- Patient is motivated and engaged
- Started early (not waiting until severe arthritis)
Injection Evidence
Research on cortisone and HA injections shows:
Strong Evidence For:
- Cortisone: Fast pain relief (within 1-2 weeks), duration 6-12 weeks
- HA: Modest pain relief starting at 2-4 weeks, duration up to 6 months
- Safety: Generally safe when properly administered
- Efficacy: Works better than placebo for most patients
Important Limitations:
- Effects are temporary
- Doesn’t improve strength or mechanics
- May enable activity but doesn’t substitute for exercise
- Repeated cortisone may damage cartilage long-term
- HA effectiveness decreases with severe arthritis
Combination Therapy Evidence
The most interesting finding: Studies comparing PT alone vs. PT plus injections show:
- Injections first, then PT - May allow better participation in exercises
- PT plus injections better than either alone - Especially in short term
- Long-term: PT benefits persist; injection benefits fade
- Best approach: Use injections to enable PT, not replace it
Which Should You Try First?
Clinical Guidelines Recommend:
Major orthopedic and rheumatology organizations (AAOS, ACR, OARSI) recommend this progression:
Tier 1: Start Here (All Patients)
- Education about OA
- Weight loss if overweight
- Physical therapy/exercise program
- Over-the-counter pain medications (as needed)
Tier 2: Add If Tier 1 Insufficient 5. Cortisone injection for acute flare-ups 6. HA injections for longer-lasting relief
Tier 3: Advanced Options 7. Stronger pain medications 8. Surgical interventions
Why PT first?
- Addresses underlying causes
- No serious side effects
- Long-lasting benefits
- Prevents progression
- May make injections unnecessary
When to Start with Injections
Injections may be appropriate as first-line treatment when:
Even in these cases: Plan to start PT once pain is manageable.
The Best Approach: Combining Both Treatments
How to Use PT and Injections Together
Strategy 1: Injection Enables PT
- Start with cortisone injection for fast pain relief
- Begin PT within 1-2 weeks while pain is reduced
- Build strength and improve mechanics during pain-free window
- Continue exercises to maintain benefits after injection wears off
Strategy 2: PT First, Injection If Needed
- Start with 6-8 weeks of physical therapy
- If progress plateaus due to pain, add HA injection
- Use pain relief from HA to advance exercise program
- Maintain gains with continued home exercises
Strategy 3: Periodic Injections + Ongoing Exercise
- Establish home exercise routine through PT
- Use HA injections 1-2×/year for maintenance relief
- Continue daily exercises for long-term benefit
- Reserve cortisone for acute flare-ups only
Key principle: Use injections as a tool to enable exercise, not a replacement for it.
Cost Comparison
Physical Therapy Costs
| Scenario | Typical Cost |
|---|---|
| With Medicare | $20-40 copay per visit |
| With private insurance | $20-50 copay per visit |
| Typical course (8-12 visits) | $160-$600 total |
| Annual cost (if ongoing) | $300-$1,000 |
Injection Costs
| Scenario | Typical Cost |
|---|---|
| Cortisone with Medicare | $50-100 per injection |
| HA with Medicare | $100-200 per series |
| Cortisone with private insurance | $50-150 per injection |
| HA with private insurance | $100-300 per series |
| Annual cost (2 HA series) | $200-$600 |
Long-Term Value
PT offers better long-term value:
- Initial investment pays off with lasting benefits
- Reduces need for repeated injections
- May delay or prevent surgery (saving thousands)
- Improves overall health beyond just knees
Injections have ongoing costs:
- Need to be repeated regularly
- Costs add up over time
- Don’t prevent disease progression
- May lead to more expensive interventions later
Real-World Scenarios
Scenario 1: Sarah, Age 68
Situation: Mild knee OA, active lifestyle, wants to keep gardening and walking
Best Approach:
- Start with physical therapy (8-10 visits)
- Learn strengthening and flexibility exercises
- Continue home program 3-4×/week
- Consider HA injection if planning extended hiking trip
Why: PT alone likely sufficient for mild OA. Builds long-term resilience.
Scenario 2: Robert, Age 72
Situation: Moderate OA with severe flare-up, can’t walk without pain
Best Approach:
- Cortisone injection for immediate relief
- Start PT within 2 weeks while pain is reduced
- Progress exercises as tolerated
- Transition to home program with periodic PT check-ins
Why: Injection enables PT participation. Combination provides short and long-term benefit.
Scenario 3: Linda, Age 70
Situation: Moderate-severe OA, not ready for surgery, tried PT but pain limited progress
Best Approach:
- HA injection series (may get longer relief than cortisone)
- Resume PT during pain-free period
- Focus on maintenance exercises
- Repeat HA every 6 months if helpful
Why: HA provides longer pain relief window. PT maintains function between injections.
Scenario 4: James, Age 65
Situation: Early OA diagnosed, minimal symptoms currently, wants to prevent worsening
Best Approach:
- PT evaluation and home exercise program
- Weight loss if overweight
- Regular exercise 4-5×/week
- Save injections for if/when symptoms worsen
Why: Prevention focus. PT can slow progression. No need for injections yet.
Making Your Decision
Questions to Ask Your Doctor
- How severe is my arthritis? (Mild, moderate, severe?)
- Am I a candidate for physical therapy?
- Is my pain level preventing me from exercising?
- Would an injection help me participate in PT?
- Do you recommend PT first, injection first, or both together?
- How many PT visits does my insurance cover?
- What injections do you typically use and why?
Decision Framework
Start with PT if:
- Your pain is manageable (3-6 out of 10)
- You can walk and do daily activities
- You’re motivated to do exercises regularly
- Your arthritis is mild to moderate
- You want long-term improvement, not just quick relief
Consider injection first if:
- Your pain is severe (7-10 out of 10)
- Pain prevents you from exercising
- You’re having an acute flare-up
- You need quick relief for an event/activity
- You’ve tried PT but pain limited progress
Plan to combine both if:
- You have moderate to severe arthritis
- You want both immediate and long-term relief
- You’re willing to do the work (PT) alongside injections
- Your goal is to delay or avoid surgery
The Bottom Line
PT and Injections Aren’t Competitors—They’re Teammates
The evidence is clear:
- Physical therapy addresses the underlying problems (weakness, poor mechanics) and provides long-lasting benefits
- Injections provide faster symptom relief and can enable you to do PT effectively
- Combined approach often works better than either alone
For most patients with knee OA:
- Start with physical therapy - It’s the foundation of long-term management
- Add injections when needed - Use them strategically to enable exercise
- Continue exercises long-term - This is what prevents progression
- Use injections periodically - For maintenance or flare-ups
The mistake to avoid: Relying only on injections without addressing muscle weakness and movement patterns. This leads to continued decline and eventual need for surgery.
The winning strategy: Use injections as a bridge to effective physical therapy, then maintain the gains with continued exercise.
Your knee health is 80% what you do yourself (exercise, weight management) and 20% what’s done to you (injections, medications). Invest in the 80%.
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How to Choose a ProviderFrequently Asked Questions
Can I do physical therapy exercises at home without seeing a PT?
While home exercises can help, an evaluation by a licensed PT ensures you’re doing the right exercises correctly. Poor form or wrong exercises can make symptoms worse. Consider at least a few visits for assessment and instruction.
How long should I try PT before considering injections?
Give PT at least 6-8 weeks of consistent effort before deciding it’s not working. Some improvement should be noticeable by 4 weeks, but maximum benefit often takes 8-12 weeks.
Will injections make physical therapy more effective?
Yes, if pain is preventing effective exercise participation. The injection provides a pain-free window to build strength. But the PT is what provides lasting benefit—not the injection.
Should I stop PT if I get an injection?
No! Continue your exercises (after resting 24-48 hours post-injection). The injection helps you do PT more comfortably and effectively.
Which type of injection works best with physical therapy?
Cortisone provides faster relief, good for acute flares. HA provides longer-lasting relief, good for maintaining PT benefits. Your doctor can recommend based on your situation.
Can PT help me avoid needing injections?
Yes. Many patients who commit to a good PT program find their pain improves enough that they don’t need injections. But if you do need them, that’s okay too—the PT still helps.
Is it too late for PT if I already have severe arthritis?
No. Even with advanced arthritis, strengthening exercises can improve function and reduce pain. You may also need injections or eventually surgery, but PT helps regardless of severity.
References
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Comparative effectiveness of nonoperative treatments for knee osteoarthritis. Annals of Internal Medicine. 2020.
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Physical therapy versus glucocorticoid injection for knee osteoarthritis. New England Journal of Medicine. 2020.
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Combined physical therapy and viscosupplementation. PM&R. 2019.
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OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis. Osteoarthritis and Cartilage. 2019.
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AAOS Clinical Practice Guideline on treatment of osteoarthritis of the knee. 2021.
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Cost-effectiveness of physical therapy vs injections for knee osteoarthritis. JAMA Network Open. 2021.
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