Abstract
Background: Carpal tunnel surgery is the most common surgical procedure performed on the hand. Although complications are rare, recurrent or persistent carpal tunnel syndrome can be a significant problem after primary decompression. Various procedures have been described for the treatment of these patients including repeat decompression and hypothenar fat pad transposition. The purpose of this study is to compare the outcomes of patients undergoing revision carpal tunnel decompression with and without hypothenar fat pad transposition. Methods: We performed a retrospective review of all patients undergoing revision carpal tunnel surgery at our institution between 2002 and 2014. Identified patients were contacted by telephone. A Boston Carpal Tunnel Questionnaire (BCTQ) was administered to all participants. Results: Seventy-six patients underwent revision carpal tunnel surgery over the study period. Twenty-nine of 45 potential participants provided a survey response (64.9%) representing a total of 33 carpal tunnel revision surgeries. Seventeen hands underwent repeat decompression alone, and 16 hands underwent repeat decompression with hypothenar fat pad transposition. A trend toward improved overall BCTQ score was noted for patients undergoing decompression alone; however, no significant difference was determined for total survey score by procedure type. Similarly, total symptom severity and functional scores were not statistically significant between groups; however, a trend toward significance for improved symptom severity score was observed in patients undergoing decompression alone. Conclusions: Our results reveal no difference in self-reported symptom severity and functional scores between patients undergoing revision carpal tunnel surgery with repeat decompression alone or decompression with fat pad transposition.
Keywords: carpal tunnel, revision carpal tunnel, hypothenar fat pad transposition
Introduction
Carpal tunnel release (CTR) for the treatment of carpal tunnel syndrome is one of the most common surgical procedures performed on the hand.4 Primary decompression can be performed through an open or endoscopic approach, both with excellent success rates.19 Although complications are rare, recurrent or persistent carpal tunnel syndrome can be a significant problem. Development of recurrent symptoms is thought to be due to postoperative adhesions, tenosynovitis, and intraneural fascicular scarring.8,10,15,16 Alternatively, persistent symptoms in patients who experience no relief or incomplete relief following primary decompression are thought to be due to an incompletely released transverse carpal ligament (TCL).8,10,15,16 This can also be due to severe preoperative compression, double crush, or other associated disease states affecting the nerve, such as diabetes.15 In many cases, however, the cause for recurrent or persistent symptoms is not readily identified.8,15,16
Multiple surgical procedures have been reported for the treatment of revision carpal tunnel surgery. Repeat simple open decompression is considered the current standard; however, several other techniques including various flap techniques have been proposed.2,3,8,16,18 Hypothenar fat pad transposition is one of the more commonly performed procedures for CTR surgery.2,5,9,12,16 With this technique, an ulnarly based pedicled flap of hypothenar fat is mobilized and interposed between the median nerve and the deep surface of the radial portion of the TCL.
The purpose of this study is to compare the long-term outcomes of patients undergoing revision carpal tunnel surgery with simple repeated open decompression versus the addition of hypothenar fat pad transposition. We hypothesize that there is no significant difference in patient-reported outcomes between simple repeat decompression and decompression with hypothenar fat pad transposition.
Methods
This study was approved by the College of Medicine institutional review board. The hospital electronic medical record was used to identify patients who underwent a carpal tunnel revision surgery between 2002 and 2014. Patients with a complete office note in the electronic medical record system were eligible for the study. Patient age, sex, date of primary and revision surgery, presenting symptoms prior to revision surgery, electromyography (EMG) results, and presence of comorbidities were recorded. All identified patients were contacted by telephone and verbal consent was obtained. These patients were verbally queried regarding recurrence of carpal tunnel symptoms and dates of any further treatment of the affected hand. Patients were excluded after telephone call attempts if they declined participation, had died, experienced cognitive impairment that would prohibit study consent, or received additional treatment for their carpal tunnel symptoms. A Boston Carpal Tunnel Questionnaire (BCTQ) was administered to all participants.11
Seventy-six patients underwent 88 revision carpal tunnel surgeries over the study period. Eight patients were excluded due to incomplete medical records, and 21 patients were lost to follow-up or deceased. Two patients were excluded due to revision for a median nerve neuroma and a severed digital nerve. Of the remaining 45 potential study participants, 1 patient refused participation and 15 patients were unable to be contacted. Twenty-nine patients provided a survey response (64.9%) representing a total of 33 carpal tunnel revision surgeries; 17 hands underwent repeat decompression alone, and 16 hands underwent repeat decompression with hypothenar fat pad transposition. All participants had clinical exam findings consistent with carpal tunnel syndrome prior to surgery. All participants except for one had an abnormal EMG with an abnormal motor exam, abnormal sensory exam, or both prior to the revision carpal tunnel procedure. Average time between primary and revision procedure was 6.2 years (range, 1 month to 29 years), and average patient follow-up from the time of revision surgery was 4.4 years (range, 1.3-12.9 years).
The mean values of continuous variables were compared using the independent t test, and the comparisons of categorical variables were assessed using the Fisher exact test. Statistical significance was defined as P < .05.
Results
No significant difference in comorbidities was determined for patients with diabetes, hypertension, hypothyroidism, or smoking status by procedure type (Table 1). No correlation was determined between demographic information and overall score (Table 1). There was no significant difference in total survey score by procedure type (P = .09). A trend toward improved symptom severity score was noted for patients undergoing decompression alone; however, this did not achieve significance (P = .07). Overall functional scores were not statistically significant between groups (P = 0.35; Table 2).
Table 1.
Patient Demographics and Procedure Type.
| Decompression (n = 17) | Transposition (n = 16) | P value | |
|---|---|---|---|
| Body mass index, mean (SD) | 32.7 (7.4) | 35.6 (11.3) | .45 |
| Age, mean (SD) | 52.4 (10.4) | 57.2 (14.6) | .29 |
| Years since primary, mean (SD) | 9.5 (9.5) | 3.0 (3.3) | .11 |
| Sex, n (%) | |||
| Men | 7 (41) | 9 (56) | .61 |
| Women | 10 (59) | 7 (44) | |
| Hand, n (%) | |||
| Left | 5 (29) | 5 (31) | 1.0 |
| Right | 12 (71) | 11 (69) | |
| Diabetes, n (%) | |||
| No | 14 (82) | 14 (88) | 1.0 |
| Yes | 3 (18) | 2 (12) | |
| Hypertension, n (%) | |||
| No | 11 (65) | 5 (31) | .08 |
| Yes | 6 (35) | 11 (69) | |
| Hypothyroidism, n (%) | |||
| No | 14 (82) | 15 (94) | .6 |
| Yes | 3 (18) | 1 (6) | |
| Smoking, n (%) | |||
| No | 13 (76) | 10 (63) | .47 |
| Yes | 4 (24) | 6 (37) | |
Table 2.
Procedure Type and Boston Carpal Tunnel Questionnaire Scores.
| Decompression (n = 17) | Transposition (n = 16) | 95% CI | P value | |
|---|---|---|---|---|
| Total score, mean (SD) | 9.53 (8.99) | 16.88 (12.80) | −1.99 to 15.0 | .09 |
| Symptom severity, mean (SD) | 0.84 (0.81) | 1.54 (1.18) | −0.09 to 1.39 | .07 |
| Functional status, mean (SD) | 1.12 (1.36) | 1.50 (1.32) | −1.14E-5 to 1.00 | .35 |
Note. CI = confidence interval.
Twenty-three patients had recurrent symptoms, and 8 patients described persistent symptoms since their primary decompression. The type of symptoms could not be determined for 2 patients undergoing revision decompression. Presence of symptoms as persistent or recurrent did not have a statistically significant effect on overall survey score when comparing patients within the same procedure group (decompression persistent vs decompression recurrent, P = .31; transposition persistent vs transposition recurrent, P = .3) or between procedure groups (decompression persistent vs transposition persistent, P = .18; decompression recurrent vs transposition recurrent, P = .71). Status of symptoms as persistent or recurrent also did not have a statistically significant effect on functional status within procedure groups (decompression persistent vs decompression recurrent, P = .42; transposition persistent vs transposition recurrent, P = .25) or between procedure groups (decompression persistent vs transposition persistent, P = .23; decompression recurrent vs transposition recurrent, P = .9). Similarly, symptoms as persistent or recurrent also did not have a statistically significant effect on symptom severity score within procedure groups (decompression persistent vs decompression recurrent, P = .44; transposition persistent vs transposition recurrent, P = .25) or between procedure groups (decompression persistent vs transposition persistent, P = .14; decompression recurrent vs transposition recurrent, P = .66).
Discussion
Carpal tunnel syndrome is the most frequently encountered entrapment neuropathy. As a result, carpal tunnel decompression is the most common surgical procedure performed on the hand.8,13 Although complications are rare, the incidence in which patients do not report a complete resolution of their symptoms is reported to range from 4% to 25%. Persistent symptoms following surgery are thought to be due to an inadequate release of the TCL, whereas recurrent symptoms are more often thought to be due to scarring of the median nerve.1,6,7,13,14,17 Scarring of the median nerve interferes with physiologic gliding during wrist motion, and it is believed that simple repeat decompression with neurolysis is not always sufficient enough to prevent new scar formation. For these cases, a hypothenar fat pad transposition is often performed. The purpose of fat pad interposition is to act as a barrier between the median nerve and the surrounding tissue, decreasing the chance of scar tissue adhering to the median nerve.2,6,12,13,16 Many studies have been performed describing good outcomes for patients undergoing revision CTR using fat pad interposition; however, no study has been performed by directly comparing fat pad interposition with simple decompression.2,5,12,16 In this study, we sought to directly compare the 2 methods as well as use the validated Boston Carpal Tunnel Questionnaire (BCTQ) to assess outcomes.
Over the 12-year study period, a total of 1973 CTRs were performed at our institution, with a revision rate of 4.5%. This number correlates with the reported rate in the literature.1 In our study, we did not see a difference in outcomes in patients undergoing simple decompression when compared with decompression with fat pad interposition. Although not statistically significant, patients undergoing decompression alone had a trend toward better overall BCTQ scores and symptom severity scores with no difference in functional scores. Although the argument can be made that the decision to perform repeat decompression with versus without fat pad interposition is made intraoperatively based on findings such as median nerve scarring or incomplete release of the TCL, there have been no studies to our knowledge that show a correlation of either treatment group having improved outcomes based on the type of revision surgery performed. In addition, there have not been any studies showing that scarring of the median nerve or incomplete release of the TCL results in recurrent or persistent carpal tunnel syndrome. Furthermore, it is our belief that these intraoperative findings are very subjective.
This study has a few limitations including the retrospective nature of the study and its small sample size due to the low rate of recurrent carpal tunnel syndrome in the general population. There is also the potential for recall bias on behalf of the patients when completing the BCTQ survey. A large prospective randomized multicentered study would be necessary to truly determine whether there is a difference in outcomes between the 2 procedures.
In conclusion, our study results indicate that the routine use of hypothenar fat pad transposition for revision carpal tunnel surgery in patients with persistent or recurrent symptoms following primary decompression may provide no benefit in patient outcomes. The significance of intraoperative findings including median nerve scarring and apparent incomplete release is yet to be elucidated; however, excellent results have been reported in our study and prior studies with both procedures. While we cannot go as far as to make a recommendation for or against the use of the hypothenar fat pad transposition based on the results of our study, we call into question the necessity of commonly performed supplementary procedures for the treatment of recurrent or persistent carpal tunnel syndrome.
Footnotes
Ethical Approval: This study was approved by our institutional review board.
Statement of Human and Animal Rights: Written consent was obtained from Pennsylvania State University institutional review board. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008.
Statement of Informed Consent: Informed consent was obtained from all individual participants included in the study.
Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
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