Latest / The Total Knee Success Podcast: Your Essential Resource for Navigating Total Knee Replacement / Episode 71:Why Your Quad Still Isn’t Working (The Real Reason Strength Doesn’t Come Back Automatically)

Transcript

Episode 71:Why Your Quad Still Isn’t Working (The Real Reason Strength Doesn’t Come Back Automatically) · The Total Knee Success Podcast: Your Essential Resource for Navigating Total Knee Replacement

• 0:00
  One of the most misunderstood parts of knee replacement
• 0:02
  rehabilitation is the difference between being
• 0:05
  active and actually rebuilding strength. Those
• 0:08
  are not always the same thing. You can walk every
• 0:10
  day and still have significant quadriceps weakness.
• 0:15
  Are you ready to get back to what you love after
• 0:17
  knee replacement? The Total Knee Success podcast
• 0:20
  is your trusted guide with practical tips, evidence
• 0:23
  -based strategies, and no fluff. It's not personal
• 0:27
  medical advice, just solid education to help
• 0:29
  you manage pain, regain mobility, and get back
• 0:32
  to living the life you love. Let's dive in. Welcome
• 0:38
  back to the Total Knee Success podcast. I'm Michelle.
• 0:42
  Have you found yourself wondering why things
• 0:44
  still feel weak even though surgery is over?
• 0:47
  Are you walking more but still struggling with
• 0:49
  stairs, standing up from a chair, or trusting
• 0:52
  your new knee when you move? Maybe you've been
• 0:55
  told your progress is going well, but deep down
• 0:57
  you still feel like the quadricep muscle group
• 1:00
  is not responding the way you expected it would.
• 1:03
  Or maybe you keep asking yourself a frustrating
• 1:05
  question. If the joint has been replaced, why
• 1:09
  doesn't the strength just come back automatically?
• 1:12
  By the end of this episode, you'll understand
• 1:14
  why your quadricep muscle group doesn't always
• 1:16
  fully wake back up on its own after a new replacement.
• 1:20
  And what that means for the way strength actually
• 1:22
  returns over time. Something I hear from people
• 1:26
  after knee replacement is, I'm doing my exercise
• 1:28
  as I'm walking more, but things still feel weak.
• 1:32
  Sometimes they describe the joint as unstable
• 1:34
  going downstairs. Sometimes they notice they
• 1:36
  fatigue quickly after standing or walking for
• 1:39
  longer periods. Other times they say they still
• 1:42
  cannot feel that muscle working the way they
• 1:45
  expect it would. And that disconnect can be frustrating
• 1:48
  because once the arthritic joint has been replaced,
• 1:51
  many people naturally expect strength to begin
• 1:53
  returning automatically. Research has shown that
• 1:56
  quadriceps' strength can drop by nearly 60 %
• 2:00
  in the first month after knee replacement. And
• 2:02
  much of that early loss comes from the nervous
• 2:04
  system temporarily losing the ability to fully
• 2:07
  activate the muscles. The quadriceps are one
• 2:11
  of the hardest -working muscle groups in the
• 2:13
  entire body. They help you stand up, climb stairs,
• 2:17
  control your balance, absorb force while walking,
• 2:19
  and support the knee joint itself. But after
• 2:23
  knee replacement, the quad often enters a protective
• 2:26
  shutdown pattern driven not just by weakness,
• 2:29
  but also by changes in the nervous system. Researchers
• 2:33
  often refer to this as arthrogenic muscle inhibition.
• 2:36
  This is when swelling, irritation, and pain signals
• 2:39
  after surgery can disrupt the nervous system's
• 2:42
  ability to fully activate the quadriceps. It's
• 2:45
  protective. Even a relatively small amount of
• 2:48
  swelling can reduce how effectively this muscle
• 2:51
  group activates, which is one reason why strength
• 2:53
  can fluctuate so much from day to day early on.
• 2:57
  That muscle group is present, but the communication
• 2:59
  between the brain and the muscle is not functioning
• 3:02
  normally yet. In other words, your quad may not
• 3:05
  be completely offline. It may simply not be activating
• 3:09
  as efficiently or as consistently as it normally
• 3:12
  would. And this is one reason the experience
• 3:15
  can feel so contradictory. You may be working
• 3:17
  consistently, walking reasonable distances, and
• 3:20
  fully participating in physical therapy, yet
• 3:22
  the quadriceps, they still feel delayed, shaky,
• 3:26
  weak, or somewhat unreliable during certain movements.
• 3:30
  What surprises many people is how early this
• 3:33
  shutdown can begin. Studies have shown that significant
• 3:36
  quadriceps inhibition can occur almost immediately
• 3:38
  after knee surgery. and may persist for months
• 3:41
  if activation and strengthening are not addressed
• 3:44
  directly. That's why simply becoming more active
• 3:48
  does not always effectively restore your strength.
• 3:52
  Walking and daily movement are both important,
• 3:54
  but walking alone often does not place enough
• 3:56
  demand on the quadriceps to reverse significant
• 3:59
  post -surgical inhibition. And this becomes especially
• 4:02
  important because many people unknowingly compensate
• 4:05
  for a weak muscle group. You may lean toward
• 4:08
  the stronger side when standing up. You may shift
• 4:11
  weight away from your operated knee when climbing
• 4:13
  stairs. You may shorten your stride while walking.
• 4:17
  You may use momentum instead of muscular control.
• 4:20
  All of these are common. Your nervous system
• 4:22
  is remarkably adaptive. It will always find an
• 4:25
  alternative strategy to keep you functioning.
• 4:28
  But compensation is not the same thing as rebuilding
• 4:31
  strength and control. This is often the point
• 4:34
  where people begin feeling stuck, especially
• 4:36
  if they assume walking more should automatically
• 4:39
  restore strength. I also want to acknowledge
• 4:42
  that for anyone dealing with ongoing weakness
• 4:44
  months after surgery, persistent quadriceps weakness
• 4:47
  after knee replacement is extremely common, even
• 4:51
  among highly motivated people who work consistently
• 4:54
  throughout physical therapy. Because many people
• 4:57
  are up and moving relatively early, like most
• 4:59
  everyone, Others may not always recognize how
• 5:02
  much strength, endurance, and control still need
• 5:05
  to be rebuilt under the surface. A 2025 longitudinal
• 5:10
  systematic review looking at physical function
• 5:12
  after total knee arthroplasty highlighted something
• 5:15
  many people recognize firsthand. Pain reduction
• 5:18
  does not automatically equal full functional
• 5:22
  improvement. Functional limitations can persist
• 5:25
  even after a technically successful surgery.
• 5:28
  And that disconnect creates some frustration
• 5:30
  because reduced pain does not automatically restore
• 5:33
  strength, stability, or movement quality. But
• 5:37
  restoring strength is a separate process that
• 5:39
  requires targeted input and progressive loading
• 5:42
  over time. Just ask your physical therapist.
• 5:46
  One of the most misunderstood parts of knee replacement
• 5:49
  rehabilitation is the difference between being
• 5:51
  active and actually rebuilding strength. Those
• 5:55
  are not always the same thing. You can walk every
• 5:57
  day and still have significant quadriceps weakness.
• 6:00
  You can stay busy, attend therapy appointments
• 6:02
  consistently, and hopefully you're doing strengthening
• 6:04
  at therapy if it's indicated at this point in
• 6:07
  your rehab. But you can do all this and still
• 6:10
  remain limited because the muscle was never fully
• 6:12
  reactivated or progressively challenged. That
• 6:16
  does not mean progress should become aggressive
• 6:18
  or painful. In fact, pushing too hard too early
• 6:22
  can increase swelling and irritation, which may
• 6:24
  worsen muscle inhibition. But it does mean that
• 6:27
  the quadriceps often require very specific retraining
• 6:31
  instead of simply hoping normal activity will
• 6:34
  restore them naturally. Talk to your physical
• 6:36
  therapist about this. Researchers have repeatedly
• 6:40
  emphasized the importance of restoring quadriceps
• 6:42
  activation after knee surgery because strength
• 6:44
  deficits are associated with poorer movement
• 6:47
  patterns and functional limitations, unfortunately.
• 6:50
  One approach that has gained renewed attention
• 6:53
  is neuromuscular electrical stimulation or NMES.
• 6:57
  And this is the electrical stimulation that's
• 6:59
  sometimes used during rehab to help the muscle
• 7:02
  contract more effectively. It's also one of those
• 7:05
  interventions that tends to generate a lot of
• 7:07
  discussion in rehabilitation because experiences,
• 7:11
  expectations, and dosing can vary quite a bit
• 7:13
  from person to person. And MES is not magic,
• 7:17
  and it's not intended to replace strengthening
• 7:19
  exercise. Instead, it's typically used alongside
• 7:22
  exercise. You're actually moving when you're
• 7:24
  using the electrical stimulation. And this is
• 7:27
  to help improve quadriceps activation during
• 7:29
  rehabilitation. And when used correctly and at
• 7:32
  a sufficient intensity, it may help overcome
• 7:35
  some of the nervous system inhibition that prevents
• 7:37
  the quad from activating fully after surgery.
• 7:41
  I know that this is true. I've seen this. work
• 7:43
  in the clinic multiple, multiple times. A 2024
• 7:47
  clinical commentary revisiting NMES emphasized
• 7:50
  something very important. Many previous studies
• 7:53
  underdosed electrical stimulation, which likely
• 7:56
  contributed to inconsistent outcomes and mixed
• 7:59
  perceptions about its effectiveness. The authors
• 8:02
  argued that sufficient intensity is critical
• 8:05
  if NMES is going to meaningfully assist quadriceps
• 8:09
  activation. I encourage this in the clinic The
• 8:12
  effort makes a difference in this intervention.
• 8:16
  Now, does every person need an MES? No. But understanding
• 8:20
  the concept reinforces an important principle.
• 8:22
  Quadriceps weakness is not always about effort
• 8:25
  alone. In many cases, the nervous system itself
• 8:28
  requires retraining, which is one reason improvement
• 8:30
  can feel sometimes uneven over time. Does this
• 8:34
  sound familiar? Some days, your new knee feels
• 8:35
  stronger and more stable. Other days, things
• 8:38
  may feel heavier, less coordinated, or more fatigued.
• 8:42
  Fatigue, swelling, pain, poor sleep, stress,
• 8:46
  inflammation, and activity load can all influence
• 8:49
  muscular activation. I think this is one of the
• 8:53
  hardest parts of the process for many people
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  because it challenges the instinct to solve the
• 8:57
  problem simply by working harder or doing more.
• 9:00
  You may have spent much of your life solving
• 9:02
  problems by working harder. So when the quad's
• 9:04
  not responding, the instinct is often to just
• 9:06
  do more, more exercises, more walking, more repetitions.
• 9:10
  But the nervous system does not always respond
• 9:12
  well to force or high, high intensity. Very often
• 9:16
  it responds better to consistency with gradual
• 9:19
  exposure, reducing swelling, improving sleep,
• 9:23
  and exercises performed with very good muscular
• 9:27
  engagement instead of a rushed repetition. And
• 9:31
  this is one reason skilled physical therapists
• 9:32
  spend so much time coaching movement quality
• 9:35
  rather than just simply counting repetitions.
• 9:37
  The goal is not merely to finish the exercise.
• 9:40
  The goal is to reconnect the communication between
• 9:43
  the brain and the muscle, so the muscle group
• 9:45
  begins participating normally again during the
• 9:48
  movement. And you may recognize this in yourself
• 9:51
  at certain points during rehab. It's very common
• 9:53
  to become more cautious with loading after surgery,
• 9:56
  especially when swelling is increased or certain
• 9:59
  movements may feel unstable or unpredictable.
• 10:02
  But rebuilding quad strength requires gradual
• 10:05
  challenging the muscle again in a way that's
• 10:07
  progressive, controlled, and consistent over
• 10:10
  time. If you avoid loading the muscle for too
• 10:12
  long because every increase in effort feels like
• 10:14
  a potential setback, it becomes much harder to
• 10:17
  rebuild strength, endurance, and confidence.
• 10:19
  Appropriately progressed strengthening is one
• 10:21
  of the ways your nervous system gradually relearns
• 10:24
  that your new knee can tolerate movement and
• 10:26
  load safely. Strength restoration after knee
• 10:30
  replacement also tends to happen in phases rather
• 10:33
  than in one smooth upward line. You may notice
• 10:36
  meaningful improvement for several weeks and
• 10:38
  then suddenly feel like things have stalled for
• 10:41
  a while, or you may regain walking tolerance
• 10:44
  before the quadricep muscle group itself feels
• 10:46
  strong enough and dependable again. A 2021 cohort
• 10:50
  study looking at walking speed trajectories after
• 10:52
  total knee arthroplasty identified different
• 10:55
  progress patterns during rehabilitation, yet
• 10:59
  people still improved function over time even
• 11:01
  when those early patterns looked very different
• 11:04
  from one another. If you've ever looked at someone
• 11:06
  else's timeline and wondered why your own strength
• 11:09
  progress feels slower or less predictable, you're
• 11:12
  definitely not alone. Two people can have the
• 11:15
  exact same procedure and experience very different
• 11:18
  strength timelines afterward. After a while,
• 11:22
  this may start to affect more than just strength.
• 11:24
  It begins affecting the way you trust your movement.
• 11:27
  When quadriceps weakness persists for too long,
• 11:30
  many people begin losing trust in their new knee
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  and that loss of confidence changes the way they
• 11:35
  move throughout the world. They become more hesitant
• 11:37
  on stairs, more cautious on an even ground, and
• 11:40
  more dependent on railings or external support.
• 11:43
  Some avoid longer outings because fatigue feels
• 11:45
  unpredictable, while others unconsciously protect
• 11:48
  their joint during everyday movement. Over time,
• 11:52
  deeply ingrained compensation patterns can continue
• 11:54
  long after the surgical tissues themselves have
• 11:57
  healed. And this is why rebuilding strength is
• 12:00
  about far more than increasing muscle size. It's
• 12:03
  also about restoring confidence in movement.
• 12:05
  That confidence usually grows through repeated
• 12:08
  evidence. Each successful movement experience
• 12:11
  helps teach both you and your nervous system
• 12:13
  that your new knee is becoming safer and more
• 12:16
  reliable. A smoother sit to stand, steadier stares,
• 12:19
  or a longer walk with less fatigue all begin
• 12:22
  rebuilding trust in your new knee. And those
• 12:24
  small improvements may seem insignificant in
• 12:27
  isolation, but together they create the foundation
• 12:30
  for long -term progress. The nervous system responds
• 12:33
  to repetition, which is one reason this process
• 12:36
  can feel mentally exhausting at times. Your brain
• 12:39
  is constantly reevaluating whether your new knee
• 12:41
  feels stable, capable, and dependable. And one
• 12:45
  thing that can be helpful during this stage is
• 12:47
  paying attention to functional improvement instead
• 12:50
  of focusing only on isolated symptoms. Rather
• 12:53
  than asking whether the quadriceps feel completely
• 12:55
  normal yet, a more helpful question may be, what
• 12:59
  are you able to do now that you could not do
• 13:01
  six weeks ago. Looking for functional changes
• 13:04
  over time often provides a much clearer picture
• 13:07
  of meaningful improvement. Are you getting out
• 13:10
  of the chair more easily than you were six weeks
• 13:12
  ago? Can you stand for longer before fatigue
• 13:14
  sets in? Are you recovering more quickly after
• 13:17
  an activity? Can you walk farther before everything
• 13:19
  starts to feel heavy or fatigued? And are stairs
• 13:22
  becoming smoother and more controlled? These
• 13:25
  kinds of changes often reflect meaningful neurologic
• 13:27
  and muscular progress. even before everything
• 13:30
  feels entirely normal again. If you're early
• 13:33
  in this process, it's also important to understand
• 13:35
  that muscular fatigue after strengthening is
• 13:38
  not automatically dangerous. Many people become
• 13:41
  concerned any time their new knee feels tired
• 13:43
  or sore after exercise because it can be difficult
• 13:46
  to tell the difference between normal muscular
• 13:49
  fatigue and something that truly needs attention.
• 13:52
  Certainly, severe swelling, spikes, sharp pain,
• 13:54
  or prolonged flare -ups, they deserve attention
• 13:56
  and discussion with your medical team. But appropriately
• 13:59
  -dosed strengthening discomfort is often a normal
• 14:02
  part of rebuilding capacity and restoring function.
• 14:07
  And one final point before we wrap up today.
• 14:10
  Rehabilitation after knee replacement is also
• 14:12
  not a one -size -fits -all. Some people move
• 14:15
  more quickly into independent strengthening,
• 14:17
  while others benefit from a more structured support
• 14:19
  and supervision along the way. Your progress
• 14:22
  does not need to look identical to someone else's.
• 14:26
  to be successful. I challenge you to stop comparing
• 14:32
  yourself to other people if that's what you're
• 14:34
  doing. If your quad feels weak right now, do
• 14:38
  not assume your opportunity for improvement has
• 14:40
  already passed. Muscular and neurologic adaptation
• 14:43
  can continue well beyond the early post -operative
• 14:46
  period. In the end, improvement usually responds
• 14:50
  best to patients. Progressive loading, consistency,
• 14:54
  good recovery habits, and active participation
• 14:56
  in the process. I know you've heard that before.
• 15:00
  It is worth repeating. Improvement usually responds
• 15:04
  best to patient's progressive loading consistency,
• 15:08
  good recovery habits, and active participation
• 15:11
  in the process. The quadriceps often require
• 15:13
  deliberate retraining before strength and control
• 15:16
  begin returning more consistently. And understand
• 15:19
  that process allows you to make better decisions,
• 15:22
  ask better questions during rehab. and take a
• 15:25
  more active role in your own long -term outcome.
• 15:28
  And if this episode helped explain why your new
• 15:30
  knee still might feel weak even though you're
• 15:32
  doing everything right, make sure you're signed
• 15:34
  up for the Total Knee Success Insider Newsletter.
• 15:37
  It's totally free. I share ongoing education
• 15:40
  and support so you can continue receiving the
• 15:42
  right information at the right stage of the process.
• 15:46
  Sometimes having the right explanation at the
• 15:47
  right time changes the entire experience. Check
• 15:52
  out the link in the show notes or go to TotalKneeSuccess
• 15:54
  .com where you can sign up for the free newsletter.
• 15:58
  In the next episode, we're continuing this series
• 16:00
  of the topic that surprises a lot of people.
• 16:03
  Why walking ability and strength do not improve
• 16:06
  at the same rate after knee replacement and what
• 16:09
  that means for how you might interpret your own
• 16:12
  progress. Thanks for joining me. I'm Michelle
• 16:14
  and this has been the Total Knee Success podcast.
• 16:21
  This podcast is for educational purposes only.
• 16:25
  Discover more at TotalMeSuccess .com and be sure
• 16:28
  to subscribe and share because every step forward
• 16:31
  takes you closer to living the life you love.