After anterior cruciate ligament surgery or ACL surgery you will experience a loss of muscle mass. You may have spent a few weeks or months building up your muscles after your ACL injury and because of this you may have assumed that your muscles would be strong and healthy after surgery. However, there are many reasons why you lose muscle mass after an ACL surgery. When you first wake up after your ACL surgery you may notice that the muscles around your surgical leg already look smaller! The main reasons for this are that overall your acitvity level has decreased, your nervous system reduces the contraction of the muscles around the knee and the presence of new swelling in your knee joint due to the surgery. Learn more about muscle loss after ACL surgery by reading this blog.

Listen to Andrew Veley, a physical therapist, talk about why you lose muscle masss after ACL surgery below.

Listen to Andrew Veley, physical therapist, explain why muscle loss occurs after an ACL surgery.

After watching the video above you may be wondering if there is a way to track your progress as you regain muscle mass after ACL surgery. A simple method called "thigh girth measurements" which you can learn about by reading this blog about how to measure the difference between your two legs by taking a thigh girth measurement. If you need a video explanation of what thigh girth measuremnts are and how they can be used to track your progress watch this short video.

Here is Andrew's full blog on muscle loss after ACL surgery.

Read all 6 of Andrew's blogs here!

If you are recovering from an ACL injury or ACL surgery and want to regain your muscle mass download our Curovate physical therapy app from the links below. Curovate provides daily video guided strengthening exercises, the ability to measure knee range of motion, in-app chat with a physical therapist to answer your surgery and recovery questions and educational blogs and webinars.

If you need further customized assistance during your ACL recovery check out our Virtual Physical Therapy page to book your 1-on-1 video session with a physical therapist.

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Other Blogs Related to ACL Surgery and Rehabilitation


1. Gerber JP, Marcus RL, Dibble LE, Greis PE, Burks RT, LaStayo PC. Effects of early progressive eccentric exercise on muscle size and function after anterior cruciate ligament reconstruction: a 1-year follow-up study of a randomized clinical trial. Phys Ther. 2009;89(1):51-59. doi:10.2522/ptj.20070189

2. Erskine RM, Fletcher G, Folland JP. The contribution of muscle hypertrophy to strength changes following resistance training. Eur J Appl Physiol. 2014;114(6):1239-1249. doi:10.1007/s00421-014-2855-4

3. Suchomel TJ, Nimphius S, Stone MH. The importance of muscular strength in athletic performance. Sports Med. 2016;46(10):1419-1449. doi:10.1007/s40279-016-0486-0

4. DeFreitas JM, Beck TW, Stock MS, Dillon MA, Kasishke PR. An examination of the time course of training-induced skeletal muscle hypertrophy. Eur J Appl Physiol. 2011;111(11):2785-2790. doi:10.1007/s00421-011-1905-4

5. Thomas AC, Wojtys EM, Brandon C, Palmieri-Smith RM. Muscle atrophy contributes to quadriceps weakness after anterior cruciate ligament reconstruction. J Sci Med Sport. 2016;19(1):7-11. doi:10.1016/j.jsams.2014.12.009

6. Bryant AL, Kelly J, Hohmann E. Neuromuscular adaptations and correlates of knee functionality following ACL reconstruction. J Orthop Res. 2008;26(1):126-135. doi:10.1002/jor.20472

7. Lepley LK, Davi SM, Burland JP, Lepley AS. Muscle atrophy after ACL injury: implications for clinical practice. Sports Health. 2020;12(6):579-586. doi:10.1177/1941738120944256

8. Fowler-Kennedy. Physiotherapy Following ACL Reconstruction Protocol. 2015. Accessed July 18, 2021.

9. van Melick N, van Cingel REH, Brooijmans F, et al. Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. Br J Sports Med. 2016;50(24):1506-1515. doi:10.1136/bjsports-2015-095898