Simultaneous Carpal Tunnel Release With Forearm Fasciotomy: Are We Doing Enough?

Abstract

Background:

Simultaneous carpal tunnel release (sCTR) with emergent forearm fasciotomy in the setting of acute compartment syndrome (ACS) has been reported, but the national incidence and cost of delayed carpal tunnel release (CTR) remain unknown. This large database study aims to evaluate how often sCTR is performed, the frequency of delayed CTR when not performed simultaneously, and the associated costs.

Methods:

The PearlDiver Mariner database was queried for patients who underwent forearm fasciotomies between January 1, 2015, and October 31, 2022. Patients were grouped based on CTR timing: simultaneous, within 2 weeks, 2 weeks to 1 year, 1 to 5 years, or no CTR. Reimbursement data were collected, and patient numbers and costs were analyzed across cohorts.

Results:

More than half of patients undergoing emergent forearm fasciotomy received sCTR. Among those who did not, 31% required CTR within 1 year and 35% within 5 years. The total cost was highest when CTR was performed within 1 year but not on the same day as fasciotomy. After 1 year, the additional cost of CTR was similar to that of patients who never underwent fasciotomy.

Conclusions:

This large database study shows that over one-third of patients who did not undergo sCTR at the time of emergent forearm fasciotomy required it within 1 year, incurring significantly higher costs. Including sCTR during initial fasciotomy may reduce delayed care and associated expenses. While these findings suggest that including sCTR during initial fasciotomy may reduce delayed care and expenses, the retrospective design precludes definitive recommendations, and clinical judgment remains essential

Level of Evidence:

4

Introduction

Acute compartment syndrome (ACS) is a true emergency of the upper extremity and requires emergent fasciotomy to relieve pressure in the affected compartments.^1,2 While decompression of the volar compartment is necessary in ACS, careful dorsal compartment release may be needed if clinical symptoms warrant. The carpal tunnel also distally compresses the volar tendons and median nerve, and can be involved in ACS. ³ The carpal tunnel acts as an independent compartment of the hand, and the resting pressure within the carpal tunnel may also be pathologically increased.

Several authors have reported performing simultaneous carpal tunnel release (sCTR) at the time of emergent forearm fasciotomy due to the close proximity of the carpal tunnel to standard volar fasciotomy incisions and the risk of median nerve compression.^3-6 A recently published a study of 166 patients found that 65% of patients with ACS undergoing emergent fasciotomy underwent sCTR. In the patients that did not have sCTR, 19% would require delayed carpal tunnel release (CTR). ⁷ However, surgeon specialty and patient clinical presentation, which likely influence the decision to perform sCTR, are not known. Additionally, some fasciotomies may be prophylactic without confirmed compartment syndrome, which impacts the necessity of sCTR.

In this large database study, we sought to analyze the national incidence of sCTR with emergent forearm fasciotomy and the associated costs of delaying CTR. We hypothesized that the majority of emergent forearm fasciotomies would be associated with sCTR, and that delaying CTR rather than performing the 2 procedures simultaneously would result in higher direct costs associated with each individual procedure.

Materials and Methods

Database

The PearlDiver Mariner Patient Claim Database (PearlDiver Technologies, Colorado Springs, CO) is one of the largest health care databases in the world and has over 41 billion patient records across a mix of payers and health care systems. The PearlDiver Mariner165 HIPAA-compliant database was used to query for patients who had undergone forearm fasciotomies from January 1, 2015, to October 31, 2022. Forearm fasciotomies were identified using the CPT codes 25020, 25023, 25024, and 25025 and CTRs were identified using the CPT codes 64721 and 29848. A cohort was created identifying patients who had undergone fasciotomy and CTR, with separate buckets for simultaneous CTR performed on the same day as the fasciotomy (sCTR), within 2 weeks from the fasciotomy, between 2 and 6 weeks, 6 weeks and 3 months, 3 months and 1 year, 1 and 5 years, and patients who did not undergo CTR at any time point. Laterality for the CTR was not specified due to the requirement of a simultaneous diagnosis of carpal tunnel syndrome (CTS) as well as forearm compartment syndrome. An estimate of revision rate was performed by querying for patients who had duplicate records in the sCTR group and each time point. Clinical variables such as compartment pressure measurements, symptom duration or severity, anesthesia type, and injury mechanism were unavailable due to database limitations. The reimbursement associated with each procedure was queried using the International Classification of Diseases (ICD) diagnosis codes ICD-10-T79A19A, T79A12A, T79A11A, M79A19, M79A12, and M79A11 for forearm compartment syndrome and ICD-10-G5600, G5601, G5602 for CTS. Reimbursement in the PearlDiver database refers to insurance payout from all payer types, not the dollar amount billed by the surgeon or practice. We use the terms cost and reimbursement interchangeably in this article but emphasize that the word cost in this paper refers to the cost to the overall health care system as defined by the dollar amount that ultimately changes hands between the payer and biller tied to the specific diagnosis. Patients within each procedural cohort were filtered by association with the ICD diagnosis code to obtain reimbursement data. Demographic data included average age, sex, Charlson Comorbidity Index (CCI), and mean family income of each patient. Approval from the author’s Institutional Review Board was obtained prior to data collection.

Statistics

Demographic data were compared between cohorts using student t tests for continuous variables and chi-squared test for categorical variables. Age was reported on the PearlDiver database as binned sets of 5 years; thus, a Shephard’s correction was applied to the standard deviation. One-way analysis of variance (ANOVA) test with a post hoc Tukey test was run to analyze differences in age, CCI, reimbursement, and mean family income based on timing of fasciotomy. A multivariate logistic regression was run at each time point, with occurrence of CTR as the event of interest and accounting for patient age, gender (men), CCI, Elixhauser Comorbidity Index (ECI), and mean family income. Reimbursement data was reported as a mean and standard deviation within each cohort. Student t tests were run on the reimbursement data using these descriptive statistics with P < .05 considered significant.

Results

Timing of Carpal Tunnel Surgery

A total of 24 098 patients who underwent forearm fasciotomy in the specified time period were identified. In total, 12 749 were women and the average age was 52.5 years (Table 1). Demographic data are presented in Table 1. More than half of the included patients (n = 12 917) underwent sCTR. However, surgeon specialty, which may influence the likelihood of performing sCTR, could not be determined. There were 1384 patients who underwent CTR within 2 weeks of the fasciotomy, 955 between 2 and 6 weeks, 445 between 6 weeks and 3 months, 708 between 3 months and 1 year, and 408 between 1 and 5 years. The overall rate of CTR after fasciotomy was 70%, with 85% of all CTR, including sCTR, occurring within 2 weeks of forearm fasciotomy. Of the patients who did not undergo sCTR (at the same time as fasciotomy), 31% and 35% went on to require CTR within 1 and 5 years, respectively, of which 4.91% and 2.42% were duplicate records suggesting revision CTR (Figure 1). One-way ANOVA testing demonstrated that women were significantly more likely to undergo sCTR and CTR overall at any time point (P < .01). Patients who underwent CTR within 2 weeks were younger and had a lower CCI compared with any other time point (P < .01). Logistic regression demonstrated that increased age was associated with a higher risk of CTR at all time points except for within the initial 2-week window, and increased CCI and ECI were associated with a decreased risk (Table 2). Male gender was associated with a decreased risk of CTR at all time points except for within the first 2 weeks and in the 1- to 5-year time frame.

Table 1.

Patient Demographics.

Variables	Total fasciotomy	Simultaneous CTR	Within 2 weeks	2-6 weeks	6-3 months	3-1 year	1-5 years	P-value
N	24 098	12 917	1384	955	445	708	408
Sex								<.01
Women (%)	12 749 (52.9)	7657 (31.8)	765 (3.2)	564 (2.3)	274 (1.1)	445 (1.8)	235 (1.0)
Men (%)	11 349 (47.1)	5260 (21.8)	619 (2.6)	391 (3.4)	171 (0.7)	263 (1.1)	173 (0.7)
Age (average)	52.5 ± 13.4	56.0 ± 14.9	52.7 ± 12.7	56.1 ± 15.6	58.0 ± 16.3	55.8 ± 15.6	57.5 ± 18.8	<.01
CCI (mean)	1.42 ± 2.19	1.17 ± 1.90	0.71 ± 1.33	1.08 ± 1.79	1.17 ± 1.78	1.28 ± 1.82	1.18 ± 1.72	<.01
ECI (mean)	3.59 ± 3.75	2.88 ± 3.2	1.88 ± 2.46	2.40 ± 2.75	2.88 ± 2.98	3.09 ± 3.18	2.78 ± 3	<.01
Family income (mean)	$73 113 ± $17 183	$72 971 ± $16 540	$72 748 ± $14 666	$71 647 ± $13 980	$73 791 ± $18 087	$79 095 ± $19 092	$71 873 ± $16 148	.57

Note. Demographics of patients included in for analysis, including sex, average age, mean Charlson Comorbidity Index (CCI), mean Elixhauser comorbidity Index (ECI), and mean family income, grouped by timing of carpal tunnel release (CTR). P-values reported per category.

Figure 1.

Timing of carpal tunnel release in patients undergoing forearm fasciotomy. Pie chart demonstrating the percentage of patients undergoing fasciotomy who also undergo CTR. Simultaneous CTR refers to CTR performed at the same time as fasciotomy.

Note. CTR = carpal tunnel release.

Table 2.

Logistic Regression for Risk of CTR at Various Time Points.

Variables	Age OR (95% CI)	P-value	CCI OR (95% CI)	P-value	ECI OR (95% CI)	P-value	Male gender OR (95% CI)	P-value	Mean family income OR (95% CI)	P-value
Simultaneous CTR	1.029 (1.027-1.030)	<.001	0.889 (0.878-0.900)	<.001	0.893 (0.886-0.899)	<.001	0.574 (0.546-0.605)		1.000 (1.000-1.000)	.005
<14 days	1.001 (0.998-1.004)	.594	0.763 (0.729-0.796)	<.001	0.822 (0.803-0.841)	<.001	0.904 (0.810-1.008)	.069	1.000 (1.000-1.000)	<.001
14 days-6 weeks	1.015 (1.010-1.019)	<.001	0.912 (0.878-0.946)	<.001	0.897 (0.877-0.917)	<.001	0.771 (0.676-0.879)		1.000 (1.000-1.000)	.113
6 weeks-3 months	1.018 (1.012-1.024)	<.001	0.941 (0.892-0.987)	.018	0.950 (0.923-0.977)	<.001	0.697 (0.574-0.843)	<.01	1.000 (1.000-1.000)	<.001
3 months-1 year	1.013 (1.008-1.018)	<.001	0.970 (0.933-1.005)	.104	0.978 (0.957-0.999)	.039	0.656 (0.561-0.765)	<.01	1.000 (1.000-1.000)	.057
1-5 years	1.021 (1.014-1.027)	<.001	0.943 (0.893-0.991)	.028	0.972 (0.944-0.999)	.048	0.824 (0.676-1.004)	.0558	1.000 (1.000-1.000)	.349

Note. Odds ratios for carpal tunnel release based on multivariate logistic regression at each time interval. P < .05 used for significance. CTR = carpal tunnel release; OR = odds ratio; CI = confidence interval; CCI = Charlson Comorbidity Index; ECI = Elixhauser Comorbidity Index.

Cost

The average cost associated with a diagnosis of forearm compartment syndrome resulting in forearm fasciotomy alone was $2639, and $2502 for patients who underwent fasciotomy and sCTR (Table 3). There was a significantly increased cost of $4220 for fasciotomy in the cohort of patients who subsequently underwent CTR within 2 weeks (P < .01). The average cost associated with CTR done on the same day as fasciotomy was $390 with a statistically significant increase to $622 within 2 weeks which was sustained at all other time points through 1 year (P < .01). CTR cost returned to $324 between 1 and 5 years. The total cost associated with the concomitant procedure of fasciotomy and CTR was lowest when CTR was performed on the same day as the fasciotomy, and higher at all other time points (Figure 2). Beyond 1 year, the additional cost of the CTR only was no different from patients who did not undergo fasciotomy.

Table 3.

Reimbursement of Forearm Fasciotomy and Carpal Tunnel Release Grouped by Timing of Carpal Tunnel Release.

Variables	Fasciotomy reimbursement ($)	CTR reimbursement ($)
No CTR	2638.92 ± 9537.88	-
Simultaneous CTR	2502.08 ± 5523.4	390.60 ± 1438.51
Within 2 weeks	4220.35 ± 6358.5*	622.90 ± 1775.69*
2-6 weeks	2193.00 ± 2892.25	881.12 ± 2159.06*
6 weeks-3 months	2999.25 ± 4223.15	630.99 ± 1859.25*
3 months-1 year	1784.86 ± 3008.33	606.16 ± 1679.20*
1-5 years	2638.92 ± 9537.88	324.45 ± 1059.18

Note. Table listing the reimbursement associated with each procedure, grouped by timing of carpal tunnel release. Reimbursement in the PearlDiver database refers to the average dollar amount reimbursed for each procedure, not the amount claimed by the provider. CTR = carpal tunnel release.

^*P < .05 when compared with the reimbursement associated with Sctr.

Figure 2.

Cost of fasciotomy and CTR grouped by timing of CTR with forearm fasciotomy. Bar chart illustrating the reimbursement totals for fasciotomy and CTR grouped by timing of CTR with forearm fasciotomy.

Note. CTR = carpal tunnel release.

Discussion

In this large database study of patients who underwent forearm fasciotomy over a 7.75-year period, we found that about a third of patients who did not undergo sCTR at the time of initial fasciotomy ended up requiring it within 1 year after fasciotomy. Hinckley et al. reported in a smaller cohort study that 19% of patients required delayed CTR at a median of 42 days after fasciotomy, when not done simultaneously. The findings in this study are corroborated by these previous results, with 21% of patients in our study undergoing CTR within the same 6-week timeframe and 31% at 1 year. We found that the incidence of sCTR performed with fasciotomies is 53% which is lower than the 64% reported by Hinckley et al, but reflects the possibility that patients who in fact undergo sCTR at the time of fasciotomy are coded under a modifier that is not captured in the PearlDiver database. This number may thus be an underestimation of the true number of sCTRs already being performed. Nevertheless, our finding that about a third of patients end up requiring CTR within 1 year supports several suggestions in the literature advocating for the inclusion of sCTR due to its proximity to the fasciotomy incision and the desire to provide complete release of the median nerve at all potential sites of compression.^1,5,8 Finally, in the 1- to 5-year period, the rate of CTR among patients who underwent forearm fasciotomy dropped to 3.6%. This still represents a 10-fold increase compared with the incidence of CTR across the general population and suggests that patients may continue to be at higher risk for needing CTR long into the future after fasciotomy, although the etiology of this is beyond the scope of this study. ⁹

There are several reasons why the remainder of patients may not be currently undergoing sCTR with forearm fasciotomy. Cobb et al injected contrast dye in a cadaver study and reported that there seemed to be no direct relationship between forearm compartment pressures and carpal tunnel pressures. ¹⁰ In clinical practice, direct measurement of pressure in the carpal tunnel is also typically not performed due to potential risk of iatrogenic injury to the median nerve. Surgeons performing emergent forearm fasciotomies may also not feel comfortable performing CTRs, although orthopedic or plastic surgeons may be more likely to perform sCTR compared with general or vascular surgeons. ⁷ However, as far as we are aware, there are no downsides to performing sCTR. Although our study does not capture symptoms potentially suffered by patients who do not undergo sCTR or answer the question of whether ultimate neurological outcomes are poorer, our study results suggest that even in the absence of measured elevated compartment pressures in the carpal tunnel, that over a third of patients still undergo a CTR after fasciotomy in a delayed fashion. The neurological symptoms these patients may suffer should not be dismissed.

The highest combined cost of fasciotomy and CTR at any point was when delayed CTR was performed within 2 weeks of the index procedure. This increased cost may reflect hospital-based procedures during the subacute period, where care is typically more expensive than in outpatient or ambulatory surgery centers. It is possible these patients may have experienced rapid development of symptoms that necessitated CTR in this early time period, but we were not able to access this granular clinical information. Interestingly, this group of patients was also younger and had a lower CCI compared with other cohorts, suggesting that they may have been involved in some type of traumatic event. Patients with a more complicated clinical course or higher CCI may also require a higher level of anesthesia than typically needed for a CTR.^11-13 Although costs associated with hospitalization such as facility, anesthesia, and intensive care unit (ICU) costs within this 2-week time period were not captured, the higher cost of fasciotomy and CTR itself may correlate with higher complexity and worse clinical status in these patients. Notably, both the cost of sCTR and CTR beyond 1 year after fasciotomy were in line with typical Medicare reimbursements for CTR across the general population. ¹⁴ Unfortunately, our data does not allow us to draw conclusions on the risks for any individual patient developing CTS following ACS. Patients who subsequently required CTR within 1 and 5 years (31% and 35%, respectively) have a much higher incidence of CTS compared with that reported for idiopathic CTS in the general population (0.1%-0.3%/year). ¹⁵ However, in patients who underwent sCTR, we found a revision rate of 4.9% within 1 year that is in line with previous studies using the same database. ¹⁶ This suggests that after the initial CTR with fasciotomy release, patients are not at higher risk for revision compared with patients undergoing primary CTR for CTS.

This study has several limitations. First, there are the limitations that are present in any large database study, including but not limited to reliance on accurate coding and the lack of granular clinical information on an individual patient level. Coding inaccuracies, missing laterality data, and lack of clinical details such as compartment pressures, symptom severity, injury mechanism, and anesthesia type limit interpretation. Additionally, this study cannot determine surgeon specialty or clinical decision-making factors affecting sCTR rates. We assume that coding was performed correctly as incorrect coding can lead to fraud claims, but there still may exist variations between providers and health care systems. The PearlDiver database certifies that providers who submit claim data fulfill an annual requirement to conduct third-party audits on the reliability and validity of their data. The database also does not support the inclusion of modifiers for coding which may help provide an estimate of which patients are more clinically complex. Our use of CPT codes to develop our cohort means that not every patient who underwent forearm fasciotomy had a diagnosis of forearm compartment syndrome, and we were unable to report the initial mechanism of injury leading to forearm fasciotomy such as blunt trauma, vascular infiltration, and crush injuries. Although we know that certain injuries that lead to ACS, such as open fractures, are known to be at higher risk for complications, we were unable to obtain the initial mechanism of injury. ¹⁷ Vascular and reperfusion injuries causing ACS are also more likely to include sCTR. ⁷ We were also not able to report information on concomitant injuries, injury severity scores, complications, or re-operations. The occurrence of clinical sequelae from delayed or missed CTR such as atrophy, neuropathy or motor deficit was also not captured. These may all have affected the cost for the care episode but were not captured in our query. An assumption was made in our query that CTR occurred on the same laterality as the forearm fasciotomy. Thus, it is possible that some patients who underwent CTR following fasciotomy actually had CTR on the contralateral side, which would overestimate the rate of delayed CTR. Finally, our estimation of revision rate of CTR does not consider the possibility of patients who had bilateral fasciotomies with CTR at separate time points. Although we estimate that this number is low, it would result in an overestimation of the revision rate stated in our article. Given the retrospective observational design and these limitations, our findings represent associations rather than causation. Thus, it is not possible to definitively recommend routine simultaneous CTR with fasciotomy based on this data alone. Clinical judgment, patient-specific factors, and intraoperative findings must guide decisions. Future prospective studies are needed to build on these findings, further clarify patient selection, and confirm the potential benefits of early intervention suggested by this analysis.

We found in this study that over a third of the patients who do not undergo sCTR at the time of emergent forearm fasciotomy went on to require it within 1 year, at significantly increased cost. The findings in this article, in line with previous literature, suggest that surgeons should consider performing CTR at the time of fasciotomy for the treatment of forearm compartment syndrome. Future areas of study should focus on risk profiling for patients who may undergo delayed CTR after fasciotomy, as well as a comparative study on clinical outcomes in patients who undergo sCTR.