After knee surgery
Do not put a pillow behind the knee after ACL reconstruction or TKA.
A pillow under the joint holds the knee bent. Protocols want a straight knee: support the heel or the calf.
After ACL reconstruction, UCSF: do not place a pillow behind the knee; put support under the heel.
After TKA, Brown Health / University Orthopedics (2023): do not sleep with a pillow under the knee; place a rolled towel or pillow behind the calf.
Shelbourne and Nitz (1990) made full extension from day 1 a pillar of accelerated ACL rehab.
Le Guen et al. (2025) associated the pillow-under-knee habit with arthrogenic muscle inhibition after knee arthroplasty.
The LYXOMED wedge follows that rest position: one plane, thigh to heel; weight on calf and heel; no ridge under the knee. This SKU has not been studied.
Do not place a pillow behind the knee after ACL reconstruction. UCSF Orthopaedic Institute
Pre and Post-Operative Instructions: ACL Reconstruction. UCSF Orthopaedic Institute, 1500 Owens Street, San Francisco, CA 94158.
Excerpt from “On day of surgery → Leg elevation,” not the full packet.
Avoid placing a pillow behind the back of your knee as this may cause stiffness and difficulty getting your knee to straighten. Place pillows or cushions under your heel instead.
UCSF Orthopaedic Institute. Pre and Post-Operative Instructions: ACL Reconstruction.
Verified 27 Aug 2026 from the original PDF.
Do not sleep with a pillow underneath the knee after TKA. University Orthopedics / Brown Health, 2023
Total Knee Arthroplasty (TKA) POST-OP REHABILITATION PROTOCOL. University Orthopedics, Inc., Adult Reconstruction Division.
Excerpt of Key Points, not the full 2-page protocol.
- DO NOT sleep with pillow underneath knee at any point after surgery
- When at rest, position knee into full extension (straight): you can place a rolled towel or pillow behind your calf to aid in achieving full extension
University Orthopedics, Inc., Adult Reconstruction Division. Total Knee Arthroplasty (TKA) POST-OP REHABILITATION PROTOCOL. 2023. Hosted by Brown Health.
Verified 27 Aug 2026 from the original PDF.
Pillow-under-knee rest is associated with arthrogenic muscle inhibition after knee arthroplasty. Le Guen et al., 2025
Le Guen A, Parratte S, Marot V, Pailhé R, Ben-Roummane H, Bérard É, Cavaignac É. Arthrogenic muscle inhibition: A prevalent issue in knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2025.
Verified 27 Aug 2026 from the journal page.
FAQ
Support the heel or calf. Do not prop the joint.
- Why not a pillow behind the knee after ACL reconstruction?
- UCSF: do not place a pillow behind the knee; put support under the heel.
- Why not a pillow under the knee after TKA?
- Brown Health / University Orthopedics (2023): do not sleep with a pillow underneath the knee; place a rolled towel or pillow behind the calf.
- Was this pillow studied?
- This SKU has not been studied. This is a positioning pillow, not a substitute for your surgeon or therapist.