Release of Tibialis Posterior Muscle Osseofascial Sheath for Chronic Exertional Compartment Syndrome Leads to Improved Outcomes

Abstract

Category: Sports Introduction/Purpose: Success rates for surgical management of chronic exertional compartment syndrome (CECS) in the lower extremity are influenced by the leg compartment involved. A failure rate of 40-50% has been associated with release of the deep posterior compartment, which has historically been associated with significantly worse outcomes than isolated anterolateral releases. The tibialis posterior muscle often resides in a separate osseofascial sheath, the so-called “fifth compartment.” At our institution, when a deep posterior release is performed, we routinely examine for this fifth compartment and release it if present. Within the context of this surgical approach, the aim of the current study was to compare long-term patient satisfaction and activity levels in those that underwent 2-versus 4-compartment fasciotomy for CECS. Methods: Our study reports on 48 limbs from 31 patients associated with a consecutive series that presented to a single institution for surgical management of lower extremity CECS from 2007-2016. The mean (standard deviation) follow-up was 65 (+/- 28) months. All patients underwent pre-operative intramuscular compartment pressure testing for CECS diagnosis. All surgeries were performed by a single surgeon. In all patients in which 4-compartment fasciotomy was indicated, the tibialis posterior muscle was examined for a separate osseofascial sheath. This sheath was released when present. The presence or absence of the sheath was always dictated in the operative note. Patient satisfaction outcomes were assessed with a Likert scale (excellent, good, fair, or poor). Current activity level was assessed via Marx and Tegner activity scores. Results: Of the 48 limbs, 29 limbs received 2-compartment anterolateral releases only and 19 limbs received 4-compartment fasciotomies. Of those that received 4-compartment fasciotomies, 13 (68%) were found to have a separate osseofascial sheath surrounding the tibialis posterior muscle. At a mean 5-year follow-up interval, 77% of the total cohort rated their outcome as good or excellent. Among the 4-comparment fasciotomy sub-cohort, 79% of patients rated their outcome as good or excellent. Among the entire cohort, there were no revision surgeries performed. The overall mean Tegner and Marx activity scores were 6 and 11 respectively. There was no significant difference in mean outcome scores between those that had 2-versus 4-compartment fasciotomies. Conclusion: Our study illustrates that 1) a separate osseofascial sheath exists around the tibialis posterior muscle in the majority of cases and 2) if this fifth compartment is consistently examined for and released, patients can achieve equivalent success rates and return to a similarly high activity level as those that undergo 2-compartment fasciotomy for CECS. Our study demonstrates superior results for 4-compartment release and includes the longest mean follow-up time for CECS patients in the literature.