TENNIS MEDICINE | Doctor's Report

🏠︎ > Practice > Sports Medicine > Tennis

I've pushed hundreds of tennis players toward surgery. Today I know: 80% didn't need it.

Dr. Michael Anderson | Orthopedics & Sports Medicine | Houston

|

(Updated: 11/18/2025)
Title

Nach 11 Monaten Schmerzen und 1.500€ verschwendet: Ein Münchner Läufer entdeckt die wahre Ursache seiner Knieschmerzen

It's hard to write this.

 

Not because of shame—though there is some, believe me. But because I know that somewhere out there, one of my former patients is reading this. Someone I told two, three years ago: "You need surgery or you can never play tennis again."

 

Someone who maybe gave up.

 

Because of me.

 

Ten months ago I stood on a tennis court in Houston and lost a match. 6-2, 6-3. The type of loss that destroyed me. Quick feet. Precise shots. Zero pain.

 

His name was Michael Berger, 51 years old. A year earlier he sat in my office. Knee pain with every stop, every movement to the side. Every slice of pain. The MRI showed meniscus damage. Partial tear, chronic irritation.

 

"At your age this doesn't heal on its own anymore," I told him. "You have two options: You get surgery, or you can never play tennis again."

 

I pushed the surgery consent form across the table.

 

He didn't sign. Said nothing. Stood up and left.

 

I thought he had given up. Had accepted that tennis was over.

 

But there he stood. On the other side of the net. Played as if nothing had ever been wrong.

 

After the match we went to the net. Shook hands. His expression was serious.

 

"Doctor," he said. Not friendly. "Do you know what the worst part was?"

 

I was silent.

 

"Not the pain. But that you told me I had to quit. Tennis is my life. And you wanted to take that away from me."

 

I swallowed. "Michael, I—"

 

"Wait."

 

He went to his bag. Pulled something out. An old, flat insole. His old standard tennis shoe insole.

 

Handed it to me.

 

"That was my problem. Not my knee. That."

 

I took the insole. Pressed my thumb in. No resistance. Completely dead. Like cardboard.

 

"Insole... Insole?"

 

"I went home. Did research—forums, videos, other players. Everyone said the same thing: Tennis-specific insoles. I ordered them. After two weeks I could play pain-free again. No surgery."

 

He looked at me. "You didn't know that, did you?"

 

I stood there, with this dead insole in my hand, and a question burned in my mind:

 

How many times have I been wrong?

What I did that night

I drove home. Couldn't sleep.

 

I sat down at my laptop. Googled "tennis insole degradation biomechanics."

 

The first study: "Compression set of EVA foams under cyclic loading" – Journal of Sports Sciences, 2019.

 

Then the second. The third. The fourth.

 

By dawn I had read twelve studies. All said the same thing:

 

EVA foam – the standard material in almost all sports shoes – loses 60-80% of its cushioning properties under repeated stress.

 

In tennis, with its stop-and-go movements, after 20-30 playing hours. That's three weeks for an active player.

 

Three weeks.

 

The next week I took time off. I spoke with sports physiologists. Called a professor of biomechanics at the University of Houston. I wanted to be sure. Wanted to know if this was really true.

 

After one week I was convinced.

 

And then I opened my patient files.

 

I'm an orthopedist specializing in sports medicine. My practice is in Houston, in the heart of one of the largest tennis clubs. Many of my patients are tennis players – about 15-20 per week. Most between 45 and 65.

 

They come with the same complaints: Heel pain. Knee pain. Achilles tendon.

 

My protocol was always the same:

  1. Patient describes pain
  2. MRI
  3. Diagnosis (inflammation, irritation, wear)
  4. Physical therapy, cortisone, surgery recommendation

70% had success. For two weeks. Maybe a month.

 

Then they came back.

 

"The PT helped, but now it's back."

 

"The cortisone shot was good for three weeks."

 

"Will this ever stop?"

 

I never understood why.

 

Now I sat there, at 3 AM, with hundreds of patient files, and understood:

 

I had been treating symptoms for years. The inflammation. The tendon. The knee.

 

The cause – the dead insole – I had never checked.

 

In 15 years. Never.

The experiment that changed everything

The next day I changed my protocol. When a tennis player reported with typical complaints – heel pain in the morning, knee pain after playing, burning in the Achilles tendon – I said on the phone: "Please bring your tennis shoes to the appointment."

 

Over the next six weeks I tested 47 tennis players.

 

This is what I found...

Patient #1: Mrs. Miller, 52 – "I don't understand anymore"

Heel spur. 18 months.

 

She sat in my office and her hands trembled slightly as she spoke.

 

"I don't understand anymore, Doctor," her voice almost broke. "The insoles from the orthopedist cost $770. Custom-made. That was... that was almost a month's salary for me. The first three weeks – finally, finally no pain. I thought: Damn. It's over. Worse than before."

 

She looked at me, her eyes moist. "What am I doing wrong?"

 

I knew the list. She had tried everything: Shockwave therapy, cortisone, custom-made insoles, YouTube exercises.

 

Every morning, the first step out of bed: Stabbing pain.

 

I asked her to go down the hall. Gait analysis. I filmed it with my phone in slow motion.

 

"See this?" I showed her the video. "Your heel barely rolls inward with each step. Only a few millimeters. Barely visible with the naked eye. That's what we call overpronation."

 

"But... I don't feel that," she said.

 

"Exactly. Nobody feels that. But with every stop on the tennis court it happens. Hundreds of times per match. That adds up. And when the insole is dead – the complete force goes directly into your heel."

 

Then I pulled out the insoles. Thumb test: No resistance. Dead.

 

I recommended she test tennis-specific insoles. Not custom-made. Just for a long-term trial.

 

Four weeks later she called me.

 

She cried. With relief.

 

"The first pain-free mornings in 18 months."

Patient #2: Mr. Klein, 55 – The question I never wanted to ask

Mr. Klein was different.

 

He had already had the surgery. Meniscus. 14 months ago.

 

The first six months: pain-free. He thought it was over.

 

Then the pain came back. Same spot. Same burning during tennis.

 

"I don't understand," he said. "The surgery was successful. Why does it hurt again?" His shoes: three months after the surgery. New. Expensive. $210.

 

The insoles: dead.

 

I sat there and suspicion burned in me.

 

The problem was probably never his meniscus. But his insoles. Even before surgery. Had he ever needed it?

 

I couldn't say for sure. I'm no savior. But the thought wouldn't let me go.

 

I didn't tell him anything about it. Not directly. Instead I explained the mechanics to him. The dead insoles. The stress on the knee. How three weeks of tennis destroys the cushioning.

 

"Your new shoes – they're already affected too," I said. "Test tennis-specific insoles. And let's see how it develops."

 

Six weeks later he called me.

 

"The pain is gone," he said. "Completely."

 

I hung up and stared at my notes.

 

Had he needed the surgery?

 

Probably not.

 

But I'll never know for sure. And that uncertainty – it remains.

Patient #3: Mr. Fischer, 61 – "At your age..."

Mr. Fischer came to me because he had heard I specialized in sports medicine.

 

"Another orthopedist told me, at my age I should quit," he said directly, without beating around the bush. No resignation in his voice. Rather: Defiance.

 

Heel spur. Mild knee pain. Both.

 

"I'm not ready to quit," he added. "Tennis keeps me fit. My wife died two years ago..." He trailed off. Cleared his throat. "Tennis is my community. My life. Not a second opinion from someone who 'understands sports.'"

 

His insoles: like paper. Wafer-thin. Dead.

 

I did the equipment check. The thumb test. Then showed him the results.

 

"It's not too bad," I said. "Your insoles are too old."

 

He blinked. "What do you mean?"

 

I explained the mechanics. The stop forces. The dead insoles. Why this can cause both heel spurs and knee pain.

 

"The other doctor saw your age," I said. "I see your insoles. That's the difference."

 

Four weeks later he called me.

 

"I play four times a week," he said. His voice sounded different. Lighter. "The other doctor was wrong. I'm not too old. I just had the wrong insoles."

What the numbers showed me

Of the 47 tennis players:

  • 39 had dead insoles (83%)
  • 33 of them are pain-free today (85%)
  • 4 still needed additional physical therapy
  • 2 needed surgery (real structural damage – but both play today with tennis insoles to prevent further damage)

After three months I called randomly selected patients. To check if it really worked.

Of 10 calls:

  • 8 pain-free
  • 1 significantly better
  • 1 no improvement

Success rate: 80%.

 

That means: Four out of five "chronic" tennis pain in players 45+ are not structural problems.

 

They're dead insoles.

What I learned about insoles (and what nobody teaches us)

The dirty secret of the shoe industry

 

Here's what's in your $150 tennis shoes:

 

The insole costs 40 cents. Maybe 50 cents if the manufacturer is generous.

 

The material is called EVA foam – the standard material in almost all sports shoes.

 

EVA is made for walking. For comfort while strolling.

 

Not for tennis.

 

Tennis isn't a running sport. It's about explosive stops. With every stop, three to four times your body weight goes through your foot.

 

175 lbs body weight = 530-700 lbs of force.

 

The insole is supposed to absorb that.

 

But EVA foam? After 20-30 playing hours – three weeks for an active player – it collapses. Permanently. It doesn't bounce back anymore.

 

When that happens, the force doesn't go into the insole.

 

It goes directly into your heel. Your knee. Your Achilles tendon.

 

Your body compensates. Inflammation. Pain. Chronic.

 

Nobody tells you that.

 

Not the manufacturer. Not the salesperson. And until ten months ago: not your doctor.

 

The shoe industry wants you to buy new shoes every six months. That's the business model.

 

Cheap insoles (40 cents) → die after three weeks → "Shoe is done" → new shoe ($150).

 

But here's the catch: The shoes are often still perfectly good – no wear on the sole – no scuffing. The upper material – like new. The shoe itself lasts two, three years.

 

Only the insole dies after three weeks.

 

Nobody says: "Just replace the insole." They say: "Time for new shoes."

 

The problem with "custom-made" insoles:

 

Many of my patients had tried custom-made insoles from an orthopedist. $530-$800.

 

"They helped three weeks. Then everything was back."

 

Now I understand why.

 

These insoles are made for walking. For posture correction. They're stiff. They're supposed to force your foot into a position.

 

But tennis requires dynamic movement. Lateral cuts. Quick direction changes.

 

A stiff insole in tennis is like ski boots in ballet. Sure, the principle is the same. It works. They don't work.

 

That's the problem:

  • Standard insoles: too soft (collapse after three weeks)
  • Orthopedic insoles: too stiff (no freedom of movement)

What tennis players need: Supporting AND dynamic.

 

Why we doctors overlook this:

 

I did six years of medical school. Five years of specialist training.

 

In those eleven years: zero hours on insoles.

 

We learn bones. Tendons. Muscles.

 

We don't learn to check equipment.

 

We assume the equipment is correct. That the $150 tennis shoe has good insoles.

 

And the players? They also assume that. They spend $150 on shoes, expect quality. Nobody thinks that the insole costs 40 cents and dies after three weeks.

 

That's our blind spot.

 

And here's something that's hard to admit: As a doctor I earn from treatments.

 

Physical therapy: $80-$100 per session. Shockwave therapy: $280. Cortisone: $240. Surgery: $5,000.

 

If I tell a patient: "Buy better insoles"?

 

I earn nothing from it.

 

The system isn't designed for us to recommend the simplest solution.

 

But I want to help. Not earn. Help.

My new protocol

Today, when a tennis player reports with typical complaints, I say on the phone: "Please bring your tennis shoes to the appointment."

 

Step 1: The Equipment Check:

 

First question: "How long have you had these shoes?"

 

Then: "May I?"

 

I take out the insole. Thumb test: I press my thumb in.

 

If it stays flat – no resistance, no bounce back – it's dead.

 

I also look at the thickness and structure. If the insole is wafer-thin, like paper, without any form – that's also a sign. If the insole is dead, I know: That's probably the problem.

 

Step 2: The honest conversation:

 

No technical terms. Simple:

 

"Your insole doesn't absorb force anymore. With every stop the stress goes directly into your knee, your heel, your tendon. That causes inflammation. That's why PT only helped temporarily – we treated the symptom."

 

Step 3: The recommendation:

 

"Before we talk about physical therapy, cortisone or surgery: Test tennis-specific insoles."

 

I explain: They absorb the stop forces. They're supporting, but dynamic. Made for tennis.

 

In recent months I've tested many brands. Some were too soft, others too stiff. OnAce was the only one that consistently performed well – the balance between support and freedom of movement.

 

But – important – I also say:

 

"The insoles are the foundation. They fix the cause. But your tendon is inflamed, your knee is irritated – that needs healing time. First weeks: only play twice. Short sessions. Then slowly increase."

 

That's realistic. The insoles aren't a miracle cure. They stop the problem. The body needs time to heal.

 

The calculation that makes everything clear:

Before:

  • Physical therapy: 8 sessions x $90 = $720
  • Cortisone: $240
  • Shockwave: $560
  • Surgery: $5,000

Total: up to $6,520.

Today:

  • Equipment check: $0
  • Tennis insoles: under $50

80% of my patients need nothing else.

Why I'm telling this

I'm not telling this to look good.

 

I'm telling this because I'll never forget Mrs. Miller – almost a month's salary – for insoles that died after three weeks.

 

I don't forget Mr. Klein. The one who had surgery that he probably never needed.

 

I don't forget Mr. Fischer. The one another doctor told he was "too old."

 

I made this mistake for 15 years.

 

Thousands of other orthopedists still make it.

Not out of incompetence. But because the system doesn't teach us to look down.

 

If your orthopedist told you:

  • "Surgery or quit"
  • "At your age..."
  • "That's chronic"
  • "We've tried everything"

Then I'm asking you:

 

Pull out your tennis shoes. Take out the insole. Press your thumb in.

 

If there's no resistance – if the insole stays flat, no structure left – then it's probably your problem.

 

Not your age. Not your tendon. Not your knee.

Your 40-cent insole.

Where you get OnAce (and why my patients are annoying me)

Here's what I didn't expect:

 

Since I started recommending OnAce, patients call me and ask: "Doctor, when is the next delivery?"

 

The problem: OnAce only produces limited quantities. The quality – supporting AND dynamic, specifically for tennis – is complex to manufacture.

 

And here's the crazy part: Most tennis players who have tried OnAce once, switch to ordering from someone else. They order every 6-12 months.

 

That means: Every new batch is gone within days. The last one? Four days. Most reorders.

 

For new customers like you, only a few remain.

 

Right now there's a special discount for new customers.

 

But I'll be honest: Be quick. Otherwise you'll have to wait until the next batch.

 

You can test OnAce risk-free for 60 days. If it doesn't work – if you don't notice a difference within 60 days – you send it back. Every cent back. No questions asked.

💡 Early Black Friday Sale

30% Off - for readers of this article

00
DAYS
00
HRS
00
MIN
00
SEC

✓ Recommended by sports orthopedists 

✓ 60-Day Comfort Guarantee 

✓ 9,600+ active players

CHECK AVAILABILITY ✨

HIGH Demand

|

DISCOUNT activated

⚠️ Almost sold out: Current batch 73% sold out

In conclusion

Last month I played against Michael again.

 

He won. 6-4, 6-3.

 

The insoles work. My backhand return doesn't.

 

At first he was angry. Understandably. I had told him he had to quit or have surgery.

 

Today we sometimes sit together after a match in the clubhouse.

 

"You didn't know better," he said recently. "Now you know. And you're helping others."

 

I'm grateful to Michael. Not for the forgiveness.

 

But for the lesson.

 

Because sometimes you have to lose first to see what you've been overlooking all these years.

Title

Dr. Michael Anderson:

  • Specialist in Orthopedics and Sports Medicine
  • Houston

CHECK AVAILABILITY ✨