Significantly lower intramuscular pressure in the posterior and lateral compartments compared with the anterior compartment suggests alterations of the diagnostic criteria for chronic exertional compartment syndrome in the lower leg

PURPOSE: To investigate distributions and identify possible differences in intramuscular pressure (IMP) values at 1 min post-exercise between the four muscle compartments of the lower leg, in patients with exertional leg pain with or without chronic exertional compartment syndrome (CECS). METHODS: A consecutive series of patients seeking orthopaedic consultation for exertional leg pain underwent IMP measurements between 2009 and 2018. The diagnosis of CECS was confirmed (n = 442) or ruled out (n = 422), based on the patient's history, clinical examination, and IMP measurements. RESULTS: The median (range) 1 min post-exercise IMP values in affected compartments in the patients diagnosed with CECS were 33 (25-53) mmHg (deep posterior), 35 (27-54) mmHg (superficial posterior), 40 (26-106) mmHg (lateral), and 47 (24-120) mmHg (anterior). In patients with no CECS, the median (range) 1 min post-exercise IMP values in the compartments were 12 (2-28) mmHg (deep posterior), 12 (2-27) mmHg (superficial posterior), 14 (2-26) mmHg (lateral), and 18 (4-34) mmHg (anterior). The IMP was significantly lower in the lateral and both posterior compartments than in the anterior compartment in both patients diagnosed with CECS and patients without CECS. CONCLUSION: The study demonstrates significantly lower IMP values in the posterior and lateral compartments compared to the anterior compartments. These findings suggest a lowering of the IMP 1 min post-exercise cut-off value for diagnosing CECS in the lateral and both posterior compartments, which may lead to improved treatment of patients with suspected CECS in the lower leg. LEVEL OF EVIDENCE: Level II.