Real time measurement of intramuscular pH during routine knee arthroscopy using a tourniquet

D. R. W. MacDonald*, D. W. Neilly, K. E. Elliott, A. J. Johnstone

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)
19 Downloads (Pure)



Tourniquets have potential adverse effects including postoperative thigh pain, likely caused by their ischaemic and possible compressive effects. The aims of this preliminary study were to determine if it is possible to directly measure intramuscular pH in human subjects over time, and to measure the intramuscular pH changes resulting from tourniquet ischaemia in patients undergoing knee arthroscopy.


For patients undergoing short knee arthroscopic procedures, a sterile calibrated pH probe was inserted into the anterior fascial compartment of the leg after skin preparation, but before tourniquet inflation. The limb was elevated for three minutes prior to tourniquet inflation to 250 mmHg or 300 mmHg. Intramuscular pH was recorded at one-second intervals throughout the procedure and for 20 minutes following tourniquet deflation. Probe-related adverse events were recorded.


A total of 27 patients were recruited to the study. Mean tourniquet time was 21 minutes (10 to 56). Tourniquet pressure was 300 mmHg for 21 patients and 250 mmHg for six patients. Mean muscle pH prior to tourniquet inflation was 6.80. Muscle pH decreased upon tourniquet inflation, with a steeper fall in the first ten minutes than for the rest of the procedure. Change in muscle pH was significant after five minutes of tourniquet ischaemia (p < 0.001). Mean muscle pH prior to tourniquet release was 6.58 and recovered to 6.75 within 20 minutes following release. No probe related adverse events were recorded.


It is possible to directly measure skeletal muscle pH in human subjects overtime. Tourniquet ischaemia results in a decrease in human skeletal muscle pH overtime during short procedures.

Original languageEnglish
Pages (from-to)363-369
Number of pages7
JournalBone & Joint Research
Issue number6
Early online date15 Jun 2021
Publication statusPublished - 15 Jun 2021

Bibliographical note

Funding statement
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.


  • Ischaemia
  • pH monitoring
  • Arthroscopy
  • Tourniquet
  • Muscle physiology


Dive into the research topics of 'Real time measurement of intramuscular pH during routine knee arthroscopy using a tourniquet'. Together they form a unique fingerprint.

Cite this