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Effect of Lower Extremity Fasciotomy Length on Intracompartmental Pressure in an Animal Model of Compartment Syndrome: The Importance of Achieving a Minimum of 90% Fascial Release James E. Mathis, Brian E. Schwartz, Jonathan D. Lester, Walter J. Kim, Jonathan N. Watson and Mark R. Hutchinson Am J Sports Med 2015 43: 75 originally published online October 31, 2014 DOI: 10.1177/0363546514554601 The online version of this article can be found at: http://ajs.sagepub.com/content/43/1/75
Published by: http://www.sagepublications.com
On behalf of: American Orthopaedic Society for Sports Medicine
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In-Depth
Effect of Lower Extremity Fasciotomy Length on Intracompartmental Pressure in an Animal Model of Compartment Syndrome The Importance of Achieving a Minimum of 90% Fascial Release James E. Mathis,* MD, Brian E. Schwartz,*y MD, Jonathan D. Lester,* MD, Walter J. Kim,* MD, Jonathan N. Watson,* MD, and Mark R. Hutchinson,* MD Investigation performed at the Department of Orthopaedic Surgery, University of Illinois at Chicago, Chicago, Illinois, USA Background: There has been an increase in minimally invasive surgery for chronic exertional compartment syndrome (CECS), despite the potential for incomplete compartment release and iatrogenic injuries. To our knowledge, no study has examined the effect of the length of fascial release on compartment pressures. Purpose/Hypothesis: The purpose was to explain the high failure rate seen in fascial release for CECS by evaluating the effect of fasciotomy length on intracompartmental pressures. We hypothesized that complete fascial release would need to be performed to return pressures to baseline levels. Study Design: Controlled laboratory study. Methods: Five male swine (10 lower extremities) were anesthetized. A slit catheter, connected to a pressure monitor, was inserted into the anterior compartment and a solution containing 5% swine albumin was injected into the compartment until the compartment pressure was .25 mm Hg for 10 minutes. Pressures were measured at rest, after the injection, and after each 10% incremental fasciotomy release. Results: The mean resting intracompartmental pressure was 3.2 mm Hg (range, 0-6 mm Hg), which increased after the injection to a mean of 37 mm Hg (range, 26-67 mm Hg). After complete fasciotomy, the mean pressure was 1.1 mm Hg (range, 0-4 mm Hg). There was a strong negative correlation (r = –0.693) between fasciotomy length and intracompartmental pressure. In 90% of the specimens, the pressures were \15 mm Hg after 80% fascial release, and after 90% release, all pressures were 8 mm Hg. Conclusion: This study demonstrates a strong correlation between fasciotomy length and a reduction in intracompartmental pressures in a swine model. Our study suggests that 90% fascial release may represent a possible watershed zone, returning the intracompartmental pressure to a value at or near baseline values. Clinical Relevance: The results suggest that even in cases with near complete fascial release, intracompartmental pressures may decrease enough to provide symptomatic relief and avoid possible iatrogenic injuries associated with percutaneous release. It is unknown whether the swine model may adequately translate to the clinical setting; thus, recommendations should be taken with caution, and future studies should be performed to examine the correlation in a human model. Keywords: chronic exertional compartment syndrome; CECS; fasciotomy
Compartment syndromes are a result of increased pressure within a closed fibro-osseous space that reduces blood flow
and tissue perfusion in the space. If intracompartmental pressures remain elevated, severe and irreversible damage may occur to muscles and nerves at risk. Chronic exertional compartment syndrome (CECS) is a cause of leg pain that is usually seen in an active population, including athletes and military personnel.19 Nonoperative management is typically ineffective or unproven in the long
The American Journal of Sports Medicine, Vol. 43, No. 1 DOI: 10.1177/0363546514554601 Ó 2014 The Author(s)
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76 Mathis et al
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Figure 1. The swine albumin solution was injected into the anterior compartment at a distance of 5 cm proximal to the insertion site of the slit catheter connected to the Stryker intracompartmental pressure monitor. The albumin solution was injected until the compartment pressure was at least 30 mm Hg and stabilized above 25 mm Hg for 10 minutes. term. Over time, greater experience and improved technology have led to the development of minimally invasive or endoscopically assisted techniques for fascial release, which allow for decreased soft tissue trauma of the lower extremity, quicker recovery, and reduction in iatrogenic damage to neurovascular and muscular structures.4,9,10,15,20 One downside of these less invasive techniques is the potential for incomplete fascial release, leading to the recurrence of symptoms. The reported rate of the recurrence of symptoms in the literature is significantly variable.3,5,16 Waterman et al18 retrospectively reviewed 611 military personal with similar demands to high-level athletes who underwent fascial release for CECS and found a symptom recurrence rate of 44.7%. This high recurrence rate could be a result of minimally invasive techniques leading to incomplete fascial release that does not sufficiently lower the intracompartmental pressure enough for the resolution of symptoms. The purpose of this study was to explain the relatively high failure rate seen in fascial release for CECS by evaluating the effect that the length of fasciotomy has on intracompartmental pressures. We hypothesized that complete fascial release would need to be performed to return intracompartmental pressures to baseline levels, as this would explain the relatively high failure rate. To our knowledge, no study has been conducted examining the extent of fascial release needed to relieve intracompartmental pressures associated with CECS.
Figure 2. The length of the tibia and corresponding fascial compartment was measured and recorded. The skin, subcutaneous tissue, and fascia of the anterior compartment were incised through a single cut in a graded fashion in increments of 10%.
MATERIALS AND METHODS Five male swine were medicated with an appropriate dose of anesthetic for induction (Telazol [Zoetis] 4.4 mg/kg 1 xylazine 2.2 mg/kg) and intubated, and intraoperative anesthesia was maintained with 2% isoflurane delivered through an endotracheal tube. Pulse oximetry was used to monitor arterial saturation throughout the procedure. Both lower extremities were then shaved and prepared. The lengths of the tibias and corresponding fascial compartments were measured and recorded. A slit catheter and Stryker intracompartmental pressure monitor (Stryker Corp) were utilized throughout the procedure for the measurement of intracompartmental pressures. The catheter was then inserted into the anterior compartment of the leg at the junction of the middle and distal thirds of the tibia. A solution containing 5% swine albumin was then injected into the anterior compartment at a distance of 5 cm proximal to the insertion site of the slit catheter. The albumin solution was injected until the compartment pressure was at least 30 mm Hg and stabilized above 25 mm Hg for 10 minutes (Figure 1). Graded, open fasciotomy of the anterior compartment was then performed in 10% increments, while the compartment pressure was continually monitored until the entire length of the fascia was released (Figure 2). The skin, subcutaneous tissue, and fascia of the anterior compartment were incised through 1 cut. The time interval between the incremental incisions was 5 minutes to allow for pressure stabilization. After completion of the fasciotomy, the protocol was then repeated on the contralateral lower extremity.
y Address correspondence to Brian E. Schwartz, MD, Department of Orthopaedic Surgery, University of Illinois at Chicago, 740 West Fulton Street, Unit 704, Chicago, IL 60601, USA (e-mail: [email protected]). *Department of Orthopaedic Surgery, University of Illinois at Chicago, Chicago, Illinois, USA. One or more of the authors has declared the following potential conflict of interest or source of funding: Funding, equipment, and specimens were provided by the Department of Orthopaedic Surgery, University of Illinois at Chicago.
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specimens had pressures greater than 5 mm Hg from baseline (6, 8, and 25 mm Hg greater than baseline level). After 90% fascial release, all specimens’ intracompartmental pressures were below 8 mm Hg, and all specimens were within 5 mm Hg of the resting pressure before the injection.
70
Compartment Pressures, mm Hg
77
60
DISCUSSION
50
40
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10
0 0
20
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Percentage of Fascia Released Pig 1 Right Pig 1 Left
Pig 2 Right Pig 2 Left
Pig 3 Right Pig 3 Left
Pig 4 Right Pig 4 Left
Pig 5 Right Pig 5 Left
Linear (Mean Resting Baseline)
Figure 3. The intracompartmental pressure of the anterior compartment (in mm Hg) as a function of the percentage of the fascia released. Note that after 90% fascial release, all 10 specimens were found to have pressures 8 mm Hg, which were all within 5 mm Hg of baseline pressures before the injection. The relationship between the length of fasciotomy and its effect on intracompartmental pressure was evaluated by linear regression with the Pearson correlation coefficient (r). The animal research experimental review board at the University of Illinois at Chicago approved the protocol for this study, and the study was performed at the Department of Orthopaedic Surgery, University of Illinois at Chicago.
RESULTS All animals were male swine with a mean age of 11.75 weeks (range, 11.0-12.5 weeks). The mean weight for the animals was 29.2 kg (range, 25.8-32.5 kg). The mean resting intracompartmental pressure was 3.2 mm Hg (range, 0-6 mm Hg). The mean compartmental length was 19.25 cm (range, 19-20 cm). The mean intracompartmental pressure after the injection was 37 mm Hg (range, 26-67 mm Hg). The mean intracompartmental pressure after fasciotomy was 1.1 mm Hg (range, 0-4 mm Hg) (Figure 3). There was a strong negative correlation between the length of fasciotomy and intracompartmental pressures (r = –0.693). The largest drop in the mean intracompartmental pressure occurred from 60% to 70% of fascial release, with a mean drop of 8.8 mm Hg. After release of 70% of the fascial compartment, 90% of the specimens experienced an intracompartmental pressure decrease of more than 50%. After 80% fascial release, the intracompartmental pressures were less than 15 mm Hg in 9 of 10 specimens, but 3 of 10
This study is the first to investigate the measured effect of the length of fasciotomy on intracompartmental pressures in the range experienced with CECS. Our study has demonstrated a strong correlation (r = –0.693) between the length of fasciotomy and the reduction in intracompartmental pressures. In the present study, 90% fascial release led to intracompartmental pressures 8 mm Hg and within 5 mm Hg of the resting pressure before the injection in all specimens. This would suggest that one must achieve 90% compartmental release at a minimum to return the intracompartmental pressure close to baseline levels. While this study clearly demonstrates a greater reduction of intracompartmental pressure with longer fasciotomy, this study along with the current literature does not demonstrate how much release is necessary to prevent symptom recurrence in a patient with CECS.1,7,13 There is a general consensus that fasciotomy is the most appropriate treatment for CECS. Historically, nonoperative treatment has rarely been effective, especially in patients looking to maintain the same activity level.3,4,11,12 More recent studies have demonstrated that nonoperative modalities such as intramuscular botulinum toxin injections have good success in the short term.7 Surgical release has been shown to be the most effective treatment option, albeit with varying results. While early studies3,16 showed success rates of around 90%, more recently, a study by Howard et al5 reported a satisfaction rate of 79%, Waterman et al18 found a symptom-free rate of only 55%, and Roberts et al14 only found improvement in 49% of patients in the military population. It is thought that failures or the recurrence of symptoms are caused by either postoperative complications or incomplete fascial release. Currently, the most common methods of fasciotomy for CECS are 1- and 2-incision percutaneous approaches and an endoscopic approach. As the techniques have become more minimally invasive, there is increasing concern of damage to neurovascular structures as well as incomplete release. An anatomic study by Hutchinson et al6 revealed damage to the superficial peroneal nerve in 4 of 6 specimens that underwent percutaneous release. They also found a mean of 8.9 mm of unreleased fascia in participants undergoing endoscopic release compared with no peroneal nerve damage and complete fascial release in all participants undergoing percutaneous release. In an anatomic study by Leversedge et al,9 14 cadaveric specimens underwent endoscopically assisted fasciotomy with a reported fascial release of 99.8% for the anterior compartment and 96.4% for the posterior compartment. An endoscopic technique described by Knight et al8 showed an improvement on visualization, but the authors conceded that there is a risk of incomplete fascial release, especially with inappropriately placed portals. There were several limitations to our study. It is still unclear as to whether the results of this study would be
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applicable in a clinical setting. It is not known whether a swine model translates to humans, and therefore, no clinical decisions can be made based on the present study. The model attempted to simulate the conditions experienced in CECS by using pressures more closely in the range of CECS and by allowing the pressure before release to stabilize for 10 minutes; however, given the short period of time during which these conditions were simulated, this may more closely simulate the local environment seen in acute compartment syndrome. Furthermore, the present study used an open technique to adequately visualize and confirm the correct percentage of fascia was released in a graded fashion. There is the possibility that if the study had been conducted using the minimally invasive techniques that are currently used in clinical practice, the intracompartmental pressures after release could have been different, being potentially higher than with open release. Also, the anesthetic used leading to a loss of muscle tone could potentially alter intracompartmental pressures, although the baseline pressures were measured after anesthetic was given. In addition, measured pressures may not accurately represent symptoms.1,7,13 There is no definitive relationship between elevated intracompartmental pressures resulting in muscle ischemia and the development of pain in patients with CECS. Balduini et al2 used phosphorous nuclear magnetic resonance spectroscopy to study skeletal metabolism in patients with CECS while symptomatic during exercise. He found that only 2 of 26 patients demonstrated ischemia, and those 2 had pressure measurements over 160 mm Hg. Last, while intracompartmental pressure remains the gold standard for diagnosing compartment syndrome, its sensitivity for detecting compartment syndrome was found to be as low as 77% in 1 study.17 The length of release required for symptomatic relief, remains uncertain, and the relationship between CECS symptoms and intracompartmental pressures is unknown. In summary, this study demonstrates a strong correlation between the length of fasciotomy and the reduction in intracompartmental pressures in a swine model. Our study would suggest that 90% fascial release may represent a so-called watershed zone, returning intracompartmental pressure to a value at or near baseline values; however, further work needs to be completed to determine whether and to what extent intracompartmental pressure relates to symptoms. Additional studies on metabolic and morphological changes at the cellular level in patients with CECS may help clarify the complex pathophysiology present as well as better explain the effect of fasciotomy in patients with CECS. Scan the QR code with your smartphone to view the In-Depth podcast associated with this article or visit http://ajsm.sagepub.com/site//misc/Index/ Podcasts.xhtml.
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REFERENCES 20. 1. Aweid O, Del Buono A, Malliaras P, et al. Systematic review and recommendations for intracompartmental pressure monitoring in
diagnosing chronic exertional compartment syndrome of the leg. Clin J Sport Med. 2012;22(4):356-370. Balduini FC, Shenton DW, O’Connor KH, Heppenstall RB. Chronic exertional compartment syndrome: correlation of compartment pressure and muscle ischemia utilizing 31P-NMR spectroscopy. Clin Sports Med. 1993;12(1):151-165. Detmer DE, Sharpe K, Sufit RL, Girdley FM. Chronic compartment syndrome: diagnosis, management, and outcomes. Am J Sports Med. 1985;13(3):162-170. George CA, Hutchinson MR. Chronic exertional compartment syndrome. Clin Sports Med. 2012;31(2):307-319. Howard JL, Mohtadi NG, Wiley JP. Evaluation of outcomes in patients following surgical treatment of chronic exertional compartment syndrome in the leg. Clin J Sport Med. 2000;10(3):176184. Hutchinson MR, Bederka B, Kopplin M. Anatomic structures at risk during minimal-incision endoscopically assisted fascial compartment releases in the leg. Am J Sports Med. 2003;31(5):764-769. Isner-Horobeti ME, Dufour SP, Blaes C, Lecocq J. Intramuscular pressure before and after botulinum toxin in chronic exertional compartment syndrome of the leg: a preliminary study. Am J Sports Med. 2013;41(11):2558-2566. Knight JR, Daniels M, Robertson W. Endoscopic compartment release for chronic exertional compartment syndrome. Arthrosc Tech. 2013;2(2):187-190. Leversedge FJ, Casey PJ, Seiler JG 3rd, Xerogeanes JW. Endoscopically assisted fasciotomy: description of technique and in vitro assessment of lower-leg compartment decompression. Am J Sports Med. 2002;30(2):272-278. Lohrer H, Nauck T. Endoscopically assisted release for exertional compartment syndromes of the lower leg. Arch Orthop Trauma Surg. 2007;127:827-834. Packer JD, Day MS, Nguyen JT, Hobart SJ, Hannafin JA, Metzl JD. Functional outcomes and patient satisfaction after fasciotomy for chronic exertional compartment syndrome. Am J Sports Med. 2013;41(2):430-436. Pedowitz RA, Hargens AR, Mubarak SJ, Gershuni DH. Modified criteria for the objective diagnosis of chronic compartment syndrome of the leg. Am J Sports Med. 1990;18(1):35-40. Roberts JA, Franklyn-Miller A. The validity of the diagnostic criteria used in chronic exertional compartment syndrome: a systematic review. Scand J Med Sci Sports. 2012;22(5):585-595. Roberts JA, Krishnasamy P, Quayle JM, Houghton JM. Outcomes of surgery for chronic exertional compartment syndrome in a military population [published online March 31, 2014]. J R Army Med Corps. doi:10.1136/jramc-2013-000191. Stein DA, Sennett BJ. One-portal endoscopically assisted fasciotomy for exertional compartment syndrome. Arthroscopy. 2005;21(1):108-112. Styf JR, Ko¨rner LM. Chronic anterior-compartment syndrome of the leg: results of treatment by fasciotomy. J Bone Joint Surg Am. 1986;68(9):1338-1347. van den Brand JG, Nelson T, Verleisdonk EJ, van der Werken C. The diagnostic value of intracompartmental pressure measurement, magnetic resonance imaging, and near-infrared spectroscopy in chronic exertional compartment syndrome: a prospective study in 50 patients. Am J Sports Med. 2005;33(5):699-704. Waterman BR, Laughlin M, Kilcoyne K, Cameron KL, Owens BD. Surgical treatment of chronic exertional compartment syndrome of the leg: failure rates and postoperative disability in an active patient population. J Bone Joint Surg Am. 2013;95(7):592-596. Waterman BR, Liu J, Newcomb R, Schoenfeld AJ, Orr JD, Belmont PJ Jr. Risk factors for chronic exertional compartment syndrome in a physically active military population. Am J Sports Med. 2013;41(11):2545-2549. Wittstein J, Moorman CT 3rd, Levin LS. Endoscopic compartment release for chronic exertional compartment syndrome: surgical technique and results. Am J Sports Med. 2010;38(8):1661-1666.
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Effect of Lower Extremity Fasciotomy Length on Intracompartmental Pressure in an Animal Model of Compartment Syndrome: The Importance of Achieving a Minimum of 90% Fascial Release James E. Mathis, Brian E. Schwartz, Jonathan D. Lester, Walter J. Kim, Jonathan N. Watson and Mark R. Hutchinson Am J Sports Med 2015 43: 75 originally published online October 31, 2014 DOI: 10.1177/0363546514554601 The online version of this article can be found at: http://ajs.sagepub.com/content/43/1/75
Published by: http://www.sagepublications.com
On behalf of: American Orthopaedic Society for Sports Medicine
Additional services and information for The American Journal of Sports Medicine can be found at: Email Alerts: http://ajs.sagepub.com/cgi/alerts Subscriptions: http://ajs.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav
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In-Depth
Effect of Lower Extremity Fasciotomy Length on Intracompartmental Pressure in an Animal Model of Compartment Syndrome The Importance of Achieving a Minimum of 90% Fascial Release James E. Mathis,* MD, Brian E. Schwartz,*y MD, Jonathan D. Lester,* MD, Walter J. Kim,* MD, Jonathan N. Watson,* MD, and Mark R. Hutchinson,* MD Investigation performed at the Department of Orthopaedic Surgery, University of Illinois at Chicago, Chicago, Illinois, USA Background: There has been an increase in minimally invasive surgery for chronic exertional compartment syndrome (CECS), despite the potential for incomplete compartment release and iatrogenic injuries. To our knowledge, no study has examined the effect of the length of fascial release on compartment pressures. Purpose/Hypothesis: The purpose was to explain the high failure rate seen in fascial release for CECS by evaluating the effect of fasciotomy length on intracompartmental pressures. We hypothesized that complete fascial release would need to be performed to return pressures to baseline levels. Study Design: Controlled laboratory study. Methods: Five male swine (10 lower extremities) were anesthetized. A slit catheter, connected to a pressure monitor, was inserted into the anterior compartment and a solution containing 5% swine albumin was injected into the compartment until the compartment pressure was .25 mm Hg for 10 minutes. Pressures were measured at rest, after the injection, and after each 10% incremental fasciotomy release. Results: The mean resting intracompartmental pressure was 3.2 mm Hg (range, 0-6 mm Hg), which increased after the injection to a mean of 37 mm Hg (range, 26-67 mm Hg). After complete fasciotomy, the mean pressure was 1.1 mm Hg (range, 0-4 mm Hg). There was a strong negative correlation (r = –0.693) between fasciotomy length and intracompartmental pressure. In 90% of the specimens, the pressures were \15 mm Hg after 80% fascial release, and after 90% release, all pressures were 8 mm Hg. Conclusion: This study demonstrates a strong correlation between fasciotomy length and a reduction in intracompartmental pressures in a swine model. Our study suggests that 90% fascial release may represent a possible watershed zone, returning the intracompartmental pressure to a value at or near baseline values. Clinical Relevance: The results suggest that even in cases with near complete fascial release, intracompartmental pressures may decrease enough to provide symptomatic relief and avoid possible iatrogenic injuries associated with percutaneous release. It is unknown whether the swine model may adequately translate to the clinical setting; thus, recommendations should be taken with caution, and future studies should be performed to examine the correlation in a human model. Keywords: chronic exertional compartment syndrome; CECS; fasciotomy
Compartment syndromes are a result of increased pressure within a closed fibro-osseous space that reduces blood flow
and tissue perfusion in the space. If intracompartmental pressures remain elevated, severe and irreversible damage may occur to muscles and nerves at risk. Chronic exertional compartment syndrome (CECS) is a cause of leg pain that is usually seen in an active population, including athletes and military personnel.19 Nonoperative management is typically ineffective or unproven in the long
The American Journal of Sports Medicine, Vol. 43, No. 1 DOI: 10.1177/0363546514554601 Ó 2014 The Author(s)
75 Downloaded from ajs.sagepub.com at SAN DIEGO STATE UNIV LIBRARY on January 27, 2015
76 Mathis et al
The American Journal of Sports Medicine
Figure 1. The swine albumin solution was injected into the anterior compartment at a distance of 5 cm proximal to the insertion site of the slit catheter connected to the Stryker intracompartmental pressure monitor. The albumin solution was injected until the compartment pressure was at least 30 mm Hg and stabilized above 25 mm Hg for 10 minutes. term. Over time, greater experience and improved technology have led to the development of minimally invasive or endoscopically assisted techniques for fascial release, which allow for decreased soft tissue trauma of the lower extremity, quicker recovery, and reduction in iatrogenic damage to neurovascular and muscular structures.4,9,10,15,20 One downside of these less invasive techniques is the potential for incomplete fascial release, leading to the recurrence of symptoms. The reported rate of the recurrence of symptoms in the literature is significantly variable.3,5,16 Waterman et al18 retrospectively reviewed 611 military personal with similar demands to high-level athletes who underwent fascial release for CECS and found a symptom recurrence rate of 44.7%. This high recurrence rate could be a result of minimally invasive techniques leading to incomplete fascial release that does not sufficiently lower the intracompartmental pressure enough for the resolution of symptoms. The purpose of this study was to explain the relatively high failure rate seen in fascial release for CECS by evaluating the effect that the length of fasciotomy has on intracompartmental pressures. We hypothesized that complete fascial release would need to be performed to return intracompartmental pressures to baseline levels, as this would explain the relatively high failure rate. To our knowledge, no study has been conducted examining the extent of fascial release needed to relieve intracompartmental pressures associated with CECS.
Figure 2. The length of the tibia and corresponding fascial compartment was measured and recorded. The skin, subcutaneous tissue, and fascia of the anterior compartment were incised through a single cut in a graded fashion in increments of 10%.
MATERIALS AND METHODS Five male swine were medicated with an appropriate dose of anesthetic for induction (Telazol [Zoetis] 4.4 mg/kg 1 xylazine 2.2 mg/kg) and intubated, and intraoperative anesthesia was maintained with 2% isoflurane delivered through an endotracheal tube. Pulse oximetry was used to monitor arterial saturation throughout the procedure. Both lower extremities were then shaved and prepared. The lengths of the tibias and corresponding fascial compartments were measured and recorded. A slit catheter and Stryker intracompartmental pressure monitor (Stryker Corp) were utilized throughout the procedure for the measurement of intracompartmental pressures. The catheter was then inserted into the anterior compartment of the leg at the junction of the middle and distal thirds of the tibia. A solution containing 5% swine albumin was then injected into the anterior compartment at a distance of 5 cm proximal to the insertion site of the slit catheter. The albumin solution was injected until the compartment pressure was at least 30 mm Hg and stabilized above 25 mm Hg for 10 minutes (Figure 1). Graded, open fasciotomy of the anterior compartment was then performed in 10% increments, while the compartment pressure was continually monitored until the entire length of the fascia was released (Figure 2). The skin, subcutaneous tissue, and fascia of the anterior compartment were incised through 1 cut. The time interval between the incremental incisions was 5 minutes to allow for pressure stabilization. After completion of the fasciotomy, the protocol was then repeated on the contralateral lower extremity.
y Address correspondence to Brian E. Schwartz, MD, Department of Orthopaedic Surgery, University of Illinois at Chicago, 740 West Fulton Street, Unit 704, Chicago, IL 60601, USA (e-mail: [email protected]). *Department of Orthopaedic Surgery, University of Illinois at Chicago, Chicago, Illinois, USA. One or more of the authors has declared the following potential conflict of interest or source of funding: Funding, equipment, and specimens were provided by the Department of Orthopaedic Surgery, University of Illinois at Chicago.
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specimens had pressures greater than 5 mm Hg from baseline (6, 8, and 25 mm Hg greater than baseline level). After 90% fascial release, all specimens’ intracompartmental pressures were below 8 mm Hg, and all specimens were within 5 mm Hg of the resting pressure before the injection.
70
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60
DISCUSSION
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40
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Percentage of Fascia Released Pig 1 Right Pig 1 Left
Pig 2 Right Pig 2 Left
Pig 3 Right Pig 3 Left
Pig 4 Right Pig 4 Left
Pig 5 Right Pig 5 Left
Linear (Mean Resting Baseline)
Figure 3. The intracompartmental pressure of the anterior compartment (in mm Hg) as a function of the percentage of the fascia released. Note that after 90% fascial release, all 10 specimens were found to have pressures 8 mm Hg, which were all within 5 mm Hg of baseline pressures before the injection. The relationship between the length of fasciotomy and its effect on intracompartmental pressure was evaluated by linear regression with the Pearson correlation coefficient (r). The animal research experimental review board at the University of Illinois at Chicago approved the protocol for this study, and the study was performed at the Department of Orthopaedic Surgery, University of Illinois at Chicago.
RESULTS All animals were male swine with a mean age of 11.75 weeks (range, 11.0-12.5 weeks). The mean weight for the animals was 29.2 kg (range, 25.8-32.5 kg). The mean resting intracompartmental pressure was 3.2 mm Hg (range, 0-6 mm Hg). The mean compartmental length was 19.25 cm (range, 19-20 cm). The mean intracompartmental pressure after the injection was 37 mm Hg (range, 26-67 mm Hg). The mean intracompartmental pressure after fasciotomy was 1.1 mm Hg (range, 0-4 mm Hg) (Figure 3). There was a strong negative correlation between the length of fasciotomy and intracompartmental pressures (r = –0.693). The largest drop in the mean intracompartmental pressure occurred from 60% to 70% of fascial release, with a mean drop of 8.8 mm Hg. After release of 70% of the fascial compartment, 90% of the specimens experienced an intracompartmental pressure decrease of more than 50%. After 80% fascial release, the intracompartmental pressures were less than 15 mm Hg in 9 of 10 specimens, but 3 of 10
This study is the first to investigate the measured effect of the length of fasciotomy on intracompartmental pressures in the range experienced with CECS. Our study has demonstrated a strong correlation (r = –0.693) between the length of fasciotomy and the reduction in intracompartmental pressures. In the present study, 90% fascial release led to intracompartmental pressures 8 mm Hg and within 5 mm Hg of the resting pressure before the injection in all specimens. This would suggest that one must achieve 90% compartmental release at a minimum to return the intracompartmental pressure close to baseline levels. While this study clearly demonstrates a greater reduction of intracompartmental pressure with longer fasciotomy, this study along with the current literature does not demonstrate how much release is necessary to prevent symptom recurrence in a patient with CECS.1,7,13 There is a general consensus that fasciotomy is the most appropriate treatment for CECS. Historically, nonoperative treatment has rarely been effective, especially in patients looking to maintain the same activity level.3,4,11,12 More recent studies have demonstrated that nonoperative modalities such as intramuscular botulinum toxin injections have good success in the short term.7 Surgical release has been shown to be the most effective treatment option, albeit with varying results. While early studies3,16 showed success rates of around 90%, more recently, a study by Howard et al5 reported a satisfaction rate of 79%, Waterman et al18 found a symptom-free rate of only 55%, and Roberts et al14 only found improvement in 49% of patients in the military population. It is thought that failures or the recurrence of symptoms are caused by either postoperative complications or incomplete fascial release. Currently, the most common methods of fasciotomy for CECS are 1- and 2-incision percutaneous approaches and an endoscopic approach. As the techniques have become more minimally invasive, there is increasing concern of damage to neurovascular structures as well as incomplete release. An anatomic study by Hutchinson et al6 revealed damage to the superficial peroneal nerve in 4 of 6 specimens that underwent percutaneous release. They also found a mean of 8.9 mm of unreleased fascia in participants undergoing endoscopic release compared with no peroneal nerve damage and complete fascial release in all participants undergoing percutaneous release. In an anatomic study by Leversedge et al,9 14 cadaveric specimens underwent endoscopically assisted fasciotomy with a reported fascial release of 99.8% for the anterior compartment and 96.4% for the posterior compartment. An endoscopic technique described by Knight et al8 showed an improvement on visualization, but the authors conceded that there is a risk of incomplete fascial release, especially with inappropriately placed portals. There were several limitations to our study. It is still unclear as to whether the results of this study would be
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applicable in a clinical setting. It is not known whether a swine model translates to humans, and therefore, no clinical decisions can be made based on the present study. The model attempted to simulate the conditions experienced in CECS by using pressures more closely in the range of CECS and by allowing the pressure before release to stabilize for 10 minutes; however, given the short period of time during which these conditions were simulated, this may more closely simulate the local environment seen in acute compartment syndrome. Furthermore, the present study used an open technique to adequately visualize and confirm the correct percentage of fascia was released in a graded fashion. There is the possibility that if the study had been conducted using the minimally invasive techniques that are currently used in clinical practice, the intracompartmental pressures after release could have been different, being potentially higher than with open release. Also, the anesthetic used leading to a loss of muscle tone could potentially alter intracompartmental pressures, although the baseline pressures were measured after anesthetic was given. In addition, measured pressures may not accurately represent symptoms.1,7,13 There is no definitive relationship between elevated intracompartmental pressures resulting in muscle ischemia and the development of pain in patients with CECS. Balduini et al2 used phosphorous nuclear magnetic resonance spectroscopy to study skeletal metabolism in patients with CECS while symptomatic during exercise. He found that only 2 of 26 patients demonstrated ischemia, and those 2 had pressure measurements over 160 mm Hg. Last, while intracompartmental pressure remains the gold standard for diagnosing compartment syndrome, its sensitivity for detecting compartment syndrome was found to be as low as 77% in 1 study.17 The length of release required for symptomatic relief, remains uncertain, and the relationship between CECS symptoms and intracompartmental pressures is unknown. In summary, this study demonstrates a strong correlation between the length of fasciotomy and the reduction in intracompartmental pressures in a swine model. Our study would suggest that 90% fascial release may represent a so-called watershed zone, returning intracompartmental pressure to a value at or near baseline values; however, further work needs to be completed to determine whether and to what extent intracompartmental pressure relates to symptoms. Additional studies on metabolic and morphological changes at the cellular level in patients with CECS may help clarify the complex pathophysiology present as well as better explain the effect of fasciotomy in patients with CECS. Scan the QR code with your smartphone to view the In-Depth podcast associated with this article or visit http://ajsm.sagepub.com/site//misc/Index/ Podcasts.xhtml.
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