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Trends in the Surgical Treatment of Cubital Tunnel Syndrome: An Analysis of the National Survey of Ambulatory Surgery Database
SCIENTIFIC ARTICLE
Trends in the Surgical Treatment of Cubital Tunnel Syndrome: An Analysis of the National Survey of Ambulatory Surgery Database Ali M. Soltani, MD, Matthew J. Best, BS, Cameron S. Francis, MD, Bassan J. Allan, MD, Zubin J. Panthaki, MD
Purpose To ascertain trends in the surgical treatment of ulnar nerve compression at the elbow within the United States. Methods We analyzed the National Survey of Ambulatory Surgery to study trends in the treatment of cubital tunnel syndrome from 1994 to 2006. The National Survey of Ambulatory Surgery provides a comprehensive overview of ambulatory surgical procedures performed in the United States. Patients identified in the database with surgically treated cubital tunnel syndrome were verified by members of our research staff and compiled into these 3 groups: decompression, transposition, and other. The data were then statistically analyzed for trends in treatment, utilization, and demographics. Results A total of 52,133 surgical procedures were recorded in the National Survey of Ambulatory Surgery for the treatment of ulnar nerve compression in 2006. This represents an increase from 26,283 in 1994 and 35,406 in 1996. In the 11 years from 1996 to 2006, the total surgical procedures on the ulnar nerve increased by 47%. Transposition went from 49% of all cubital tunnel procedures in the 1990s to 38% in 2006. In 2006, women were much more likely to have a simple decompression (70%) than a transposition or other technique. Decompression had a mean surgical time of 48 minutes, and transposition had a mean surgical time of 59 minutes. Conclusions The percentage of transpositions used in the treatment of cubital syndrome has decreased to 37% in the last survey. Possible reasons include expanded indications or changing surgical preferences. (J Hand Surg 2013;38A:1551–1556. Copyright © 2013 by the American Society for Surgery of the Hand. All rights reserved.) Type of study/level of evidence Prognostic II. Key words Cubital tunnel syndrome, hand surgery, healthcare survey, peripheral nerve surgery, ulnar nerve compression. the ulnar nerve at the elbow, or cubital tunnel syndrome, is the second-most common nerve compression syndrome after carpal tunnel syndrome.1– 6 Its incidence
C
OMPRESSION NEUROPATHY OF
From the Department of Surgery, Division of Plastic, Aesthetic, and Reconstructive Surgery, University of Miami, Miller School of Medicine, Miami, FL; Department of Surgery, Division of Plastic and Reconstructive Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA. Received for publication January 30, 2013; accepted in revised form April 29, 2013.
has been estimated at 25 cases per 100,000 personyears.7– 8 Prior reports have shown that men are affected at a higher rate than women.8 –9 Surgical treatment of cubital tunnel syndrome is varied and, most Correspondingauthor:AliM.Soltani,MD,1120NW14thSt.,CRBSte402,Miami,FL33136;e-mail: [email protected]. 0363-5023/13/38A08-0014$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2013.04.044
No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
© ASSH 䉬 Published by Elsevier, Inc. All rights reserved. 䉬 1551
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TRENDS IN CUBITAL TUNNEL SYNDROME
often, is based on surgeon preference.8,10 There have been a multitude of reports on surgical techniques of the cubital tunnel, with simple decompression and transposition of the ulnar nerve being the 2 most common techniques. Decompressions have been reported via the traditional open or the newer endoscopic method.3,4,6,8,10 –19 Transposition can be performed by the subcutaneous, submuscular, intramuscular, or subfascial techniques.8,10,20 –24 Before 2005, there were only case series and expert opinion studies on the clinical outcomes of the surgical treatment of primary cubital tunnel syndrome. However, since then, there have been 4 prospective, randomized clinical trials assessing the efficacy of these different techniques.1,11,13,17 Most notably, a recent large meta-analysis demonstrated no difference in clinical outcomes or motor nerve conduction velocities between the differently treated groups, decompression or transposition.25 In the absence of superiority of one technique, most surgeons would prefer to perform the surgery with the least morbidity. In addition, with the advent of insurance-driven cost containment, most hand surgery procedures such as carpal tunnel release, Dupuytren fasciectomy, and cubital tunnel release are done on an outpatient basis. These ambulatory procedures can be done in a freestanding surgery center or hospital. We sought to study the demographics, utilization, and surgical technique patterns of the treatment of cubital tunnel syndrome in the United States, and studied the associated costs, operative times, and comorbid conditions found in the latest survey data.
MATERIALS AND METHODS National Survey of Ambulatory Surgery The National Survey of Ambulatory Surgery (NSAS) was analyzed to study current trends in the surgical treatment of compression neuropathy of the ulnar nerve at the elbow. This study was classified as exempt for institutional review board purposes. The NSAS provides a comprehensive overview of ambulatory surgical procedures performed in the United States.26 The NSAS is a national study of ambulatory surgical care in both hospital-based and freestanding ambulatory surgery centers. The survey was conducted by the National Center for Health Statistics at the Centers for Disease Control and Prevention. The primary objective of the NSAS sample selection was to obtain a representative sample of outpatient surgery in the United States for surveillance. The NSAS was conducted in 1994 and again in 1996 and 2006.
Inclusion criteria The International Classification of Diseases (ICD), Ninth Revision, Clinical Modification was used to identify patients diagnosed with cubital tunnel syndrome. Cases with diagnosis code 354.2 were identified and selected. The medical information that was recorded on the sample patient abstracts was coded by National Center for Health Statistics contract staff. Cases with the ICD-9-Clinical Modification procedure coding indicating surgical treatment of cubital tunnel syndrome were included in the study. The current ICD coding has different treatment codes for surgical procedures treating compression neuropathy of the ulnar nerve. Codes 04.49 and 04.04 indicate simple decompression of the ulnar nerve at the elbow, code 04.60 indicates transposition of the ulnar nerve at the elbow, and code 04.79 indicates surgical treatment of cubital tunnel syndrome by other method. These diagnosis and treatment codes were then verified by 2 members of our research staff and compiled into 3 groups: decompression, transposition, and other. All data presented by the NSAS were then recorded for each of these groups, including sex, age, facility type, insurance type, surgical time, recovery time, anesthesia, diagnoses, and procedures. For the 2006 data year, surgical times were compiled by the formula (time surgery ended - time surgery started). Surgical costs were provided by the NSAS and reflect the direct total costs of the operating room. Statistical methods We analyzed the 1994, 1996, and 2006 NSAS data using a sampling weighting method. The NSAS data were collected based on a probabilistic sample scheme. Therefore, we used sampling weights (the inverse of selection probability) provided by the Centers for Disease Control and Prevention to account for unequal sampling probabilities and to produce estimates for all visits to ambulatory centers in the United States. Due to sampling differences between years, we did not make statistical comparisons between years, but within sample years, we did use statistical methods to draw conclusions. We analyzed the 1994, 1996, and 2006 NSAS databases separately. We used the Rao-Scott chi-square statistic to evaluate differences in categorical variables and a regression analysis for continuous variables, with resultant P values. A Taylor linearization model provided by the Centers for Disease Control and Prevention estimates was used to calculate the standard error and confidence intervals of the data. We selected a 95% confidence interval along with a point estimate to define population parameters. These confidence intervals, when compared between years, can be suggestive of
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FIGURE 1: Incidence of surgical procedures on cubital tunnel by year.
statistical differences in the data if non-overlapping. However, direct statistical comparison between years could not be performed due to sampling differences in the database. RESULTS Totals and type of operation A total of 52,133 surgical procedures (95% CI, 46,941– 57,325) were recorded by the NSAS for the treatment of ulnar nerve compression in 2006. This represents an increase from 26,283 (95% CI, 24,003–28,533) in 1994 and 35,406 (95% CI, 32,432–38,380) in 1996. In the 11 years from 1996 to 2006, the total surgical procedures on the ulnar nerve increased by 47%. As a percentage of total surgical procedures on the cubital tunnel, transposition decreased over the past 11 years, from 49% of all cubital tunnel procedures in the 1990s to 38% in 2006 (Fig. 1). Sex In the 1990s, the ratio of men to women having operations for cubital tunnel syndrome was roughly equal, with men comprising 51% of cases in 1994 and 50% of
cases in 1996. However, in 2006, men made up approximately 60% of the surgical population. In 2006, men also had simple decompression in 51% of cases, whereas women were much more likely to have a simple decompression (70%), Rao-Scott corrected chisquare, P ⬍ .001. Age The mean age at time of surgery increased throughout the study period from 47 (95% CI, 43–51) in 1994 to 48 (95% CI, 44 –52) in 1996 and 50 (95% CI, 44 –55) in the 2006 survey (Fig. 2). Notable in the 2006 data, the age groups 40 – 49 and 60 – 69 had the largest increases in size, and patients under 20 almost exclusively had a simple decompression performed (92%). Of note, estimates for age groups 20 –29 and for 20 and below have a large relative standard error and could be unreliable. Facility type In 1994, 82% percent of procedures were performed in a hospital setting. In 1996 it remained at 83%; however, by 2006, this had decreased to 47%. Therefore, in 2006,
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FIGURE 2: Incidence of surgical procedures on cubital tunnel by year and age.
TABLE 1.
Types of Anesthesia Administered, by Year
Year
Topical
Intravenous
Monitored Anesthesia Care
Block
General
Other
1994
6%
24%
3%
34%
52%
4%
1996
11%
10%
9%
30%
50%
5%
2006
10%
27%
18%
25%
61%
4%
Total percentages by year are greater than 100% due to cases in which multiple types of anesthesia were used.
most procedures were done in a freestanding surgery center (53%). Anesthesia type Table 1 demonstrates trends in the type of anesthesia administered. General anesthesia use increased from approximately 50% in the 1990 data sets to 61% in 2006. The use of blocks declined from 34% in 1994 to 25% in 2006. Monitored anesthesia care increased from 3% in 1994 to 18% in 2006. Type of insurance Medicare slowly decreased as a percentage of insurance used for cubital tunnel syndrome surgery, as shown in the pie charts in Figure 3. Workers’ compensation coverage decreased from 32% of cases in 1994 to approximately 25% in 2006. 2006 surgical details (time, cost, comorbidities) Decompression had a mean surgical time of 48 minutes (95% CI, 41–54), and transposition had a mean surgical
time of 59 minutes (95% CI, 52– 65), survey regression analysis P ⫽ .04. The mean cost of decompression was $6,447 (95% CI, $5,079 to $7,814), whereas transposition was $6,738 (95% CI, $5,371 to $8,105), P ⫽ .807. DISCUSSION In the 1990s, transpositions represented approximately half of surgically treated cases, but as shown in our database analysis, the latest survey percentage has decreased to 37%. Overall surgical volume has increased, but decompressions have become much more frequent. We hypothesize that one reason for this change is an increasing body of evidence showing no difference in clinical outcome between the different surgical techniques. In 1995, Nathan et al reported on their outcomes with in situ decompression in 131 patients with successful results.27 This was followed by other studies demonstrating the effectiveness of in situ decompression.28 –30 Prospective, randomized, controlled trial results1,11,13 demonstrating the clinical equivalence of
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FIGURE 3: Type of insurance used by year.
decompression with transposition were published twice in 2005 and once in 2006. Another reason for the increased frequency of decompression could be a relaxation of indications for treatment of cubital tunnel syndrome. The overall population of patients presenting with cubital tunnel syndrome might have had milder symptoms in 2006 and thus the frequency of decompressions rose. Preoperative clinical severity or electrodiagnostic data were not recorded in the NSAS database and may have been different from year to year. The cohort of patients categorized under the ICD code for cubital tunnel syndrome, 354.2, contains a heterogeneous population with varying degrees of severity and etiologies. Some authors have suggested surgical treatment of cubital tunnel syndrome without electrodiagnostic testing or even with normal electrodiagnostic studies.31–32 Thus, the indications for surgery may have expanded between study years, accounting for the increase in decompressions. However, there are limitations to our analysis of the NSAS. The NSAS contains data only on outpatient surgical procedures performed in a hospital or surgery center. It does not include inpatient data, such as procedures with associated trauma, ulnar nerve lacerations, and hospitalized patients. This could have the potential for selection bias in the study population. Through the 13-year period of our database analysis, other points were notable. The number of males having surgical treatment of the cubital tunnel increased over the years at a greater rate than females. The mean age
of the surgical population increased, possibly reflecting the aging demographics of the United States. Surgical facilities had changes as well, reflecting cost savings and efficiencies in outpatient surgery. The majority of ambulatory cubital tunnel procedures in the last NSAS data were being performed in freestanding surgical centers, a large change from prior surveys in the 1990s, when greater than 80% of procedures were performed in a hospital setting. Reduced total health care costs have been realized as a result of the shift to ambulatory surgery centers.33 There are many factors possibly contributing to the increased use of ambulatory surgery centers: insurer policies, patient preference, surgeon preference, and demonstrated safety.34 –36 Further, the use of ambulatory surgery centers has increased with physician ownership of these ambulatory surgery centers, with more profitable elective procedures being performed there.37 Additional data regarding cost, surgical time, and demographics were collected in the 2006 data set. Transposition took, on average, 11 minutes longer than in situ decompression. Further, the costs associated with transposition were greater, although they did not reach statistical significance. In the 2006 survey, women were much more likely to have a simple decompression than men, by approximately a 20% margin. Reasons for this are unclear; possibly women presented earlier or had milder symptoms and surgeons are more likely to choose a decompression. Prior published reports have suggested that men tend to have more severe symptoms and tend to be treated with transposition, so the NSAS
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data confirm that finding.3,11 Finally, there were some fluctuations in the type of anesthesia, and the use of regional blocks decreased in the last data set. Possible changing payer reimbursement patterns, improved monitored anesthesia care, or other efficiencies may have contributed to the decreased rate. REFERENCES 1. Bartels RH, Verhagen WI, van der Wilt GJ, et al. Prospective randomized controlled study comparing simple decompression versus anterior subcutaneous transposition for idiopathic neuropathy of the ulnar nerve at the elbow: Part 1. Neurosurgery. 2005;56(3):522– 530; discussion 522–530. 2. Bozentka DJ. Cubital tunnel syndrome pathophysiology. Clin Orthop Relat Res. 1998;(351):90 –94. 3. Mowlavi A, Andrews K, Lille S, et al. The management of cubital tunnel syndrome: a meta-analysis of clinical studies. Plast Reconstr Surg. 2000;106(2):327–334. 4. Nabhan A, Ahlhelm F, Kelm J, et al. Simple decompression or subcutaneous anterior transposition of the ulnar nerve for cubital tunnel syndrome. J Hand Surg Br. 2005;30(5):521–524. 5. Palmer BA, Hughes TB. Cubital tunnel syndrome. J Hand Surg Am. 2010;35(1):153–163. 6. Tsai TM, Chen IC, Majd ME, et al. Cubital tunnel release with endoscopic assistance: results of a new technique. J Hand Surg Am. 1999;24(1):21–29. 7. Mondelli M, Giannini F, Ballerini M, et al. Incidence of ulnar neuropathy at the elbow in the province of Siena (Italy). J Neurol Sci. 2005;234(1–2):5–10. 8. Zlowodzki M, Chan S, Bhandari M, et al. Anterior transposition compared with simple decompression for treatment of cubital tunnel syndrome. A meta-analysis of randomized, controlled trials. J Bone Joint Surg Am. 2007;89(12):2591–2598. 9. Gay JR, Love JG. Diagnosis and treatment of tardy paralysis of the ulnar nerve; based on a study of 100 cases. J Bone Joint Surg Am. 1947;29(4):1087–1097. 10. Novak CB, Mackinnon SE. Selection of operative procedures for cubital tunnel syndrome. Hand (N Y). 2009;4(1):50 –54. 11. Biggs M, Curtis JA. Randomized, prospective study comparing ulnar neurolysis in situ with submuscular transposition. Neurosurgery. 2006;58(2):296 –304; discussion 296 –304. 12. Feindel W, Stratford J. Cubital tunnel compression in tardy ulnar palsy. Can Med Assoc J. 1958;78(5):351–353. 13. Gervasio O, Gambardella G, Zaccone C, et al. Simple decompression versus anterior submuscular transposition of the ulnar nerve in severe cubital tunnel syndrome: a prospective randomized study. Neurosurgery. 2005;56(1):108 –117; discussion 117. 14. Goldfarb CA, Sutter MM, Martens EJ, et al. Incidence of re-operation and subjective outcome following in situ decompression of the ulnar nerve at the cubital tunnel. J Hand Surg Eur Vol. 2009;34(3): 379 –383. 15. Heithoff SJ. Cubital tunnel syndrome does not require transposition of the ulnar nerve. J Hand Surg Am. 1999;24(5):898 –905. 16. Hoffmann R, Siemionow M. The endoscopic management of cubital tunnel syndrome. J Hand Surg Br. 2006;31(1):23–29. 17. Keiner D, Gaab MR, Schroeder HW, et al. Comparison of the long-term results of anterior transposition of the ulnar nerve or simple decompression in the treatment of cubital tunnel syndrome–a prospective study. Acta Neurochir (Wien). 2009;151(4):311–315; discussion 316.
18. King T. The treatment of traumatic ulnar neuritis; mobilization of the ulnar nerve at the elbow by removal of the medial epicondyle and adjacent bone. Aust N Z J Surg. 1950;20(1):33– 42. 19. Ogata K, Manske PR, Lesker PA. The effect of surgical dissection on regional blood flow to the ulnar nerve in the cubital tunnel. Clin Orthop Relat Res. 1985;(193):195–198. 20. Charles YP, Coulet B, Rouzaud JC, et al. Comparative clinical outcomes of submuscular and subcutaneous transposition of the ulnar nerve for cubital tunnel syndrome. J Hand Surg Am. 2009;34(5): 866 – 874. 21. Conway FM. Traumatic ulnar neuritis: with especial reference to the late or tardy ulnar paralysis. Ann Surg. 1933;97(3):425– 433. 22. Craven PR Jr, Green DP. Cubital tunnel syndrome. Treatment by medial epicondylectomy. J Bone Joint Surg Am. 1980;62(6):986 – 989. 23. Greenwald D, Blum LC III, Adams D, et al. Effective surgical treatment of cubital tunnel syndrome based on provocative clinical testing without electrodiagnostics. Plast Reconstr Surg. 2006;117(5): 87e–91e. 24. Osterman AL, Davis CA. Subcutaneous transposition of the ulnar nerve for treatment of cubital tunnel syndrome. Hand Clin. 1996; 12(2):421– 433. 25. Macadam SA, Gandhi R, Bezuhly M, et al. Simple decompression vs anterior subcutaneous and submuscular transposition of the ulnar nerve for cubital tunnel syndrome: a meta-analysis. J Hand Surg Am. 2008;33(8):1314.e1–12. 26. National Center for Health Statistics. National Survey of Ambulatory Surgery. Available at: http://www.cdc.gov/nchs/nsas.htm. Accessed 2012 Dec 11. 27. Nathan PA, Keniston RC, Meadows KD. Outcome study of ulnar nerve compression at the elbow treated with simple decompression and an early programme of physical therapy. J Hand Surg Br. 1995;20(5):628 – 637. 28. Heithoff SJ. Cubital tunnel syndrome does not require transposition of the ulnar nerve. J Hand Surg Am. 1999;24(5):898 –905. 29. Filippi R, Farag S, Reisch R, et al. Cubital tunnel syndrome. Treatment by decompression without transposition of ulnar nerve. Minim Invasive Neurosurg. 2002;45(3):164 –168. 30. Taniguchi Y, Takami M, Takami T, et al. Simple decompression with small skin incision for cubital tunnel syndrome. J Hand Surg Br. 2002;27(6):559 –562. 31. Greenwald D, Moffitt M, Cooper B. Effective surgical treatment of cubital tunnel syndrome based on provocative clinical testing without electrodiagnostics. Plast Reconstr Surg. 1999;104(1):215–218. 32. Tomaino MM, Brach PJ, Vansickle DP. The rationale for and efficacy of surgical intervention for electrodiagnostic-negative cubital tunnel syndrome. J Hand Surg Am. 2001;26(6):1077–1081. 33. Koenig L, Gu Q. Growth of ambulatory surgical centers, surgery volume, and savings to medicare. Am J Gastroenterol. 2013;108(1): 10 –15. 34. Kozak LJ, McCarthy E, Pokras R. Changing patterns of surgical care in the United States, 1980 –1995. Health Care Financ Rev. 1999; 21(1):31– 49. 35. Haugh R. Competition keeps getting hotter for ambulatory surgery. Hosp Health Netw. 2006;80(10):68 –70, 72. 36. Sun GH, Demonner S, Davis MM. Epidemiological and economic trends in inpatient and outpatient thyroidectomy in the United States, 1996 –2006. Thyroid. 2012 Nov 22 [Epub ahead of print]. 37. Plotzke MR, Courtemanche C. Does procedure profitability impact whether an outpatient surgery is performed at an ambulatory surgery center or hospital? Health Econ. 2011;20(7):817– 830.
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Trends in the Surgical Treatment of Cubital Tunnel Syndrome: An Analysis of the National Survey of Ambulatory Surgery Database Ali M. Soltani, MD, Matthew J. Best, BS, Cameron S. Francis, MD, Bassan J. Allan, MD, Zubin J. Panthaki, MD
Purpose To ascertain trends in the surgical treatment of ulnar nerve compression at the elbow within the United States. Methods We analyzed the National Survey of Ambulatory Surgery to study trends in the treatment of cubital tunnel syndrome from 1994 to 2006. The National Survey of Ambulatory Surgery provides a comprehensive overview of ambulatory surgical procedures performed in the United States. Patients identified in the database with surgically treated cubital tunnel syndrome were verified by members of our research staff and compiled into these 3 groups: decompression, transposition, and other. The data were then statistically analyzed for trends in treatment, utilization, and demographics. Results A total of 52,133 surgical procedures were recorded in the National Survey of Ambulatory Surgery for the treatment of ulnar nerve compression in 2006. This represents an increase from 26,283 in 1994 and 35,406 in 1996. In the 11 years from 1996 to 2006, the total surgical procedures on the ulnar nerve increased by 47%. Transposition went from 49% of all cubital tunnel procedures in the 1990s to 38% in 2006. In 2006, women were much more likely to have a simple decompression (70%) than a transposition or other technique. Decompression had a mean surgical time of 48 minutes, and transposition had a mean surgical time of 59 minutes. Conclusions The percentage of transpositions used in the treatment of cubital syndrome has decreased to 37% in the last survey. Possible reasons include expanded indications or changing surgical preferences. (J Hand Surg 2013;38A:1551–1556. Copyright © 2013 by the American Society for Surgery of the Hand. All rights reserved.) Type of study/level of evidence Prognostic II. Key words Cubital tunnel syndrome, hand surgery, healthcare survey, peripheral nerve surgery, ulnar nerve compression. the ulnar nerve at the elbow, or cubital tunnel syndrome, is the second-most common nerve compression syndrome after carpal tunnel syndrome.1– 6 Its incidence
C
OMPRESSION NEUROPATHY OF
From the Department of Surgery, Division of Plastic, Aesthetic, and Reconstructive Surgery, University of Miami, Miller School of Medicine, Miami, FL; Department of Surgery, Division of Plastic and Reconstructive Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA. Received for publication January 30, 2013; accepted in revised form April 29, 2013.
has been estimated at 25 cases per 100,000 personyears.7– 8 Prior reports have shown that men are affected at a higher rate than women.8 –9 Surgical treatment of cubital tunnel syndrome is varied and, most Correspondingauthor:AliM.Soltani,MD,1120NW14thSt.,CRBSte402,Miami,FL33136;e-mail: [email protected]. 0363-5023/13/38A08-0014$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2013.04.044
No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
© ASSH 䉬 Published by Elsevier, Inc. All rights reserved. 䉬 1551
1552
TRENDS IN CUBITAL TUNNEL SYNDROME
often, is based on surgeon preference.8,10 There have been a multitude of reports on surgical techniques of the cubital tunnel, with simple decompression and transposition of the ulnar nerve being the 2 most common techniques. Decompressions have been reported via the traditional open or the newer endoscopic method.3,4,6,8,10 –19 Transposition can be performed by the subcutaneous, submuscular, intramuscular, or subfascial techniques.8,10,20 –24 Before 2005, there were only case series and expert opinion studies on the clinical outcomes of the surgical treatment of primary cubital tunnel syndrome. However, since then, there have been 4 prospective, randomized clinical trials assessing the efficacy of these different techniques.1,11,13,17 Most notably, a recent large meta-analysis demonstrated no difference in clinical outcomes or motor nerve conduction velocities between the differently treated groups, decompression or transposition.25 In the absence of superiority of one technique, most surgeons would prefer to perform the surgery with the least morbidity. In addition, with the advent of insurance-driven cost containment, most hand surgery procedures such as carpal tunnel release, Dupuytren fasciectomy, and cubital tunnel release are done on an outpatient basis. These ambulatory procedures can be done in a freestanding surgery center or hospital. We sought to study the demographics, utilization, and surgical technique patterns of the treatment of cubital tunnel syndrome in the United States, and studied the associated costs, operative times, and comorbid conditions found in the latest survey data.
MATERIALS AND METHODS National Survey of Ambulatory Surgery The National Survey of Ambulatory Surgery (NSAS) was analyzed to study current trends in the surgical treatment of compression neuropathy of the ulnar nerve at the elbow. This study was classified as exempt for institutional review board purposes. The NSAS provides a comprehensive overview of ambulatory surgical procedures performed in the United States.26 The NSAS is a national study of ambulatory surgical care in both hospital-based and freestanding ambulatory surgery centers. The survey was conducted by the National Center for Health Statistics at the Centers for Disease Control and Prevention. The primary objective of the NSAS sample selection was to obtain a representative sample of outpatient surgery in the United States for surveillance. The NSAS was conducted in 1994 and again in 1996 and 2006.
Inclusion criteria The International Classification of Diseases (ICD), Ninth Revision, Clinical Modification was used to identify patients diagnosed with cubital tunnel syndrome. Cases with diagnosis code 354.2 were identified and selected. The medical information that was recorded on the sample patient abstracts was coded by National Center for Health Statistics contract staff. Cases with the ICD-9-Clinical Modification procedure coding indicating surgical treatment of cubital tunnel syndrome were included in the study. The current ICD coding has different treatment codes for surgical procedures treating compression neuropathy of the ulnar nerve. Codes 04.49 and 04.04 indicate simple decompression of the ulnar nerve at the elbow, code 04.60 indicates transposition of the ulnar nerve at the elbow, and code 04.79 indicates surgical treatment of cubital tunnel syndrome by other method. These diagnosis and treatment codes were then verified by 2 members of our research staff and compiled into 3 groups: decompression, transposition, and other. All data presented by the NSAS were then recorded for each of these groups, including sex, age, facility type, insurance type, surgical time, recovery time, anesthesia, diagnoses, and procedures. For the 2006 data year, surgical times were compiled by the formula (time surgery ended - time surgery started). Surgical costs were provided by the NSAS and reflect the direct total costs of the operating room. Statistical methods We analyzed the 1994, 1996, and 2006 NSAS data using a sampling weighting method. The NSAS data were collected based on a probabilistic sample scheme. Therefore, we used sampling weights (the inverse of selection probability) provided by the Centers for Disease Control and Prevention to account for unequal sampling probabilities and to produce estimates for all visits to ambulatory centers in the United States. Due to sampling differences between years, we did not make statistical comparisons between years, but within sample years, we did use statistical methods to draw conclusions. We analyzed the 1994, 1996, and 2006 NSAS databases separately. We used the Rao-Scott chi-square statistic to evaluate differences in categorical variables and a regression analysis for continuous variables, with resultant P values. A Taylor linearization model provided by the Centers for Disease Control and Prevention estimates was used to calculate the standard error and confidence intervals of the data. We selected a 95% confidence interval along with a point estimate to define population parameters. These confidence intervals, when compared between years, can be suggestive of
JHS 䉬 Vol A, August
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1553
FIGURE 1: Incidence of surgical procedures on cubital tunnel by year.
statistical differences in the data if non-overlapping. However, direct statistical comparison between years could not be performed due to sampling differences in the database. RESULTS Totals and type of operation A total of 52,133 surgical procedures (95% CI, 46,941– 57,325) were recorded by the NSAS for the treatment of ulnar nerve compression in 2006. This represents an increase from 26,283 (95% CI, 24,003–28,533) in 1994 and 35,406 (95% CI, 32,432–38,380) in 1996. In the 11 years from 1996 to 2006, the total surgical procedures on the ulnar nerve increased by 47%. As a percentage of total surgical procedures on the cubital tunnel, transposition decreased over the past 11 years, from 49% of all cubital tunnel procedures in the 1990s to 38% in 2006 (Fig. 1). Sex In the 1990s, the ratio of men to women having operations for cubital tunnel syndrome was roughly equal, with men comprising 51% of cases in 1994 and 50% of
cases in 1996. However, in 2006, men made up approximately 60% of the surgical population. In 2006, men also had simple decompression in 51% of cases, whereas women were much more likely to have a simple decompression (70%), Rao-Scott corrected chisquare, P ⬍ .001. Age The mean age at time of surgery increased throughout the study period from 47 (95% CI, 43–51) in 1994 to 48 (95% CI, 44 –52) in 1996 and 50 (95% CI, 44 –55) in the 2006 survey (Fig. 2). Notable in the 2006 data, the age groups 40 – 49 and 60 – 69 had the largest increases in size, and patients under 20 almost exclusively had a simple decompression performed (92%). Of note, estimates for age groups 20 –29 and for 20 and below have a large relative standard error and could be unreliable. Facility type In 1994, 82% percent of procedures were performed in a hospital setting. In 1996 it remained at 83%; however, by 2006, this had decreased to 47%. Therefore, in 2006,
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FIGURE 2: Incidence of surgical procedures on cubital tunnel by year and age.
TABLE 1.
Types of Anesthesia Administered, by Year
Year
Topical
Intravenous
Monitored Anesthesia Care
Block
General
Other
1994
6%
24%
3%
34%
52%
4%
1996
11%
10%
9%
30%
50%
5%
2006
10%
27%
18%
25%
61%
4%
Total percentages by year are greater than 100% due to cases in which multiple types of anesthesia were used.
most procedures were done in a freestanding surgery center (53%). Anesthesia type Table 1 demonstrates trends in the type of anesthesia administered. General anesthesia use increased from approximately 50% in the 1990 data sets to 61% in 2006. The use of blocks declined from 34% in 1994 to 25% in 2006. Monitored anesthesia care increased from 3% in 1994 to 18% in 2006. Type of insurance Medicare slowly decreased as a percentage of insurance used for cubital tunnel syndrome surgery, as shown in the pie charts in Figure 3. Workers’ compensation coverage decreased from 32% of cases in 1994 to approximately 25% in 2006. 2006 surgical details (time, cost, comorbidities) Decompression had a mean surgical time of 48 minutes (95% CI, 41–54), and transposition had a mean surgical
time of 59 minutes (95% CI, 52– 65), survey regression analysis P ⫽ .04. The mean cost of decompression was $6,447 (95% CI, $5,079 to $7,814), whereas transposition was $6,738 (95% CI, $5,371 to $8,105), P ⫽ .807. DISCUSSION In the 1990s, transpositions represented approximately half of surgically treated cases, but as shown in our database analysis, the latest survey percentage has decreased to 37%. Overall surgical volume has increased, but decompressions have become much more frequent. We hypothesize that one reason for this change is an increasing body of evidence showing no difference in clinical outcome between the different surgical techniques. In 1995, Nathan et al reported on their outcomes with in situ decompression in 131 patients with successful results.27 This was followed by other studies demonstrating the effectiveness of in situ decompression.28 –30 Prospective, randomized, controlled trial results1,11,13 demonstrating the clinical equivalence of
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FIGURE 3: Type of insurance used by year.
decompression with transposition were published twice in 2005 and once in 2006. Another reason for the increased frequency of decompression could be a relaxation of indications for treatment of cubital tunnel syndrome. The overall population of patients presenting with cubital tunnel syndrome might have had milder symptoms in 2006 and thus the frequency of decompressions rose. Preoperative clinical severity or electrodiagnostic data were not recorded in the NSAS database and may have been different from year to year. The cohort of patients categorized under the ICD code for cubital tunnel syndrome, 354.2, contains a heterogeneous population with varying degrees of severity and etiologies. Some authors have suggested surgical treatment of cubital tunnel syndrome without electrodiagnostic testing or even with normal electrodiagnostic studies.31–32 Thus, the indications for surgery may have expanded between study years, accounting for the increase in decompressions. However, there are limitations to our analysis of the NSAS. The NSAS contains data only on outpatient surgical procedures performed in a hospital or surgery center. It does not include inpatient data, such as procedures with associated trauma, ulnar nerve lacerations, and hospitalized patients. This could have the potential for selection bias in the study population. Through the 13-year period of our database analysis, other points were notable. The number of males having surgical treatment of the cubital tunnel increased over the years at a greater rate than females. The mean age
of the surgical population increased, possibly reflecting the aging demographics of the United States. Surgical facilities had changes as well, reflecting cost savings and efficiencies in outpatient surgery. The majority of ambulatory cubital tunnel procedures in the last NSAS data were being performed in freestanding surgical centers, a large change from prior surveys in the 1990s, when greater than 80% of procedures were performed in a hospital setting. Reduced total health care costs have been realized as a result of the shift to ambulatory surgery centers.33 There are many factors possibly contributing to the increased use of ambulatory surgery centers: insurer policies, patient preference, surgeon preference, and demonstrated safety.34 –36 Further, the use of ambulatory surgery centers has increased with physician ownership of these ambulatory surgery centers, with more profitable elective procedures being performed there.37 Additional data regarding cost, surgical time, and demographics were collected in the 2006 data set. Transposition took, on average, 11 minutes longer than in situ decompression. Further, the costs associated with transposition were greater, although they did not reach statistical significance. In the 2006 survey, women were much more likely to have a simple decompression than men, by approximately a 20% margin. Reasons for this are unclear; possibly women presented earlier or had milder symptoms and surgeons are more likely to choose a decompression. Prior published reports have suggested that men tend to have more severe symptoms and tend to be treated with transposition, so the NSAS
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data confirm that finding.3,11 Finally, there were some fluctuations in the type of anesthesia, and the use of regional blocks decreased in the last data set. Possible changing payer reimbursement patterns, improved monitored anesthesia care, or other efficiencies may have contributed to the decreased rate. REFERENCES 1. Bartels RH, Verhagen WI, van der Wilt GJ, et al. Prospective randomized controlled study comparing simple decompression versus anterior subcutaneous transposition for idiopathic neuropathy of the ulnar nerve at the elbow: Part 1. Neurosurgery. 2005;56(3):522– 530; discussion 522–530. 2. Bozentka DJ. Cubital tunnel syndrome pathophysiology. Clin Orthop Relat Res. 1998;(351):90 –94. 3. Mowlavi A, Andrews K, Lille S, et al. The management of cubital tunnel syndrome: a meta-analysis of clinical studies. Plast Reconstr Surg. 2000;106(2):327–334. 4. Nabhan A, Ahlhelm F, Kelm J, et al. Simple decompression or subcutaneous anterior transposition of the ulnar nerve for cubital tunnel syndrome. J Hand Surg Br. 2005;30(5):521–524. 5. Palmer BA, Hughes TB. Cubital tunnel syndrome. J Hand Surg Am. 2010;35(1):153–163. 6. Tsai TM, Chen IC, Majd ME, et al. Cubital tunnel release with endoscopic assistance: results of a new technique. J Hand Surg Am. 1999;24(1):21–29. 7. Mondelli M, Giannini F, Ballerini M, et al. Incidence of ulnar neuropathy at the elbow in the province of Siena (Italy). J Neurol Sci. 2005;234(1–2):5–10. 8. Zlowodzki M, Chan S, Bhandari M, et al. Anterior transposition compared with simple decompression for treatment of cubital tunnel syndrome. A meta-analysis of randomized, controlled trials. J Bone Joint Surg Am. 2007;89(12):2591–2598. 9. Gay JR, Love JG. Diagnosis and treatment of tardy paralysis of the ulnar nerve; based on a study of 100 cases. J Bone Joint Surg Am. 1947;29(4):1087–1097. 10. Novak CB, Mackinnon SE. Selection of operative procedures for cubital tunnel syndrome. Hand (N Y). 2009;4(1):50 –54. 11. Biggs M, Curtis JA. Randomized, prospective study comparing ulnar neurolysis in situ with submuscular transposition. Neurosurgery. 2006;58(2):296 –304; discussion 296 –304. 12. Feindel W, Stratford J. Cubital tunnel compression in tardy ulnar palsy. Can Med Assoc J. 1958;78(5):351–353. 13. Gervasio O, Gambardella G, Zaccone C, et al. Simple decompression versus anterior submuscular transposition of the ulnar nerve in severe cubital tunnel syndrome: a prospective randomized study. Neurosurgery. 2005;56(1):108 –117; discussion 117. 14. Goldfarb CA, Sutter MM, Martens EJ, et al. Incidence of re-operation and subjective outcome following in situ decompression of the ulnar nerve at the cubital tunnel. J Hand Surg Eur Vol. 2009;34(3): 379 –383. 15. Heithoff SJ. Cubital tunnel syndrome does not require transposition of the ulnar nerve. J Hand Surg Am. 1999;24(5):898 –905. 16. Hoffmann R, Siemionow M. The endoscopic management of cubital tunnel syndrome. J Hand Surg Br. 2006;31(1):23–29. 17. Keiner D, Gaab MR, Schroeder HW, et al. Comparison of the long-term results of anterior transposition of the ulnar nerve or simple decompression in the treatment of cubital tunnel syndrome–a prospective study. Acta Neurochir (Wien). 2009;151(4):311–315; discussion 316.
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