Long-term Patient-Reported Outcomes After Surgery for Hypothenar Hammer Syndrome

Abstract

Background: This study aims to describe the long-term patient-reported outcomes after surgery for hypothenar hammer syndrome (HTHS) and to identify factors associated with inferior outcomes. Methods: We retrospectively identified 27 patients who underwent surgical intervention for HTHS from 2002 to 2016. Fifteen patients (56%) completed outcome questionnaires: Quick Disabilities of the Arm, Shoulder, and Hand, Cold Intolerance Symptom Severity (CISS) survey, Patient-Reported Outcomes Measurement Information System Upper Extremity Computer Adaptive Test, and Patient-Reported Outcomes Measurement Information System Pain Interference Computer Adaptive Test. The median questionnaire follow-up was 7.2 years (interquartile range, 3.1-9.9). Outcomes were compared across different surgical techniques, and the influence of patient-related factors on outcomes was also evaluated. Results: Six (40%) patients experienced complete symptom resolution, 6 (40%) had improvement without complete resolution, 1 (7%) had resolution followed by recurrence, and 2 (13%) reported no improvement. The most common symptom after surgical intervention was cold intolerance. Questionnaire scores were similar across ligation, direct repair, and vein graft vascular reconstruction. Patients had better CISS scores if they had surgery on their nondominant hand (13.2 vs 38.6) and did not have a manual labor job (18.1 vs 40.5). Conclusions: Surgery for HTHS leads to moderate long-term improvement in patient-reported outcomes. Different surgical techniques yield similar symptomatic relief. Manual labor and surgery of the dominant hand are associated with worse CISS scores.

Introduction

Hypothenar hammer syndrome (HTHS) is a rare form of digital ischemia caused by thrombosis and/or aneurysmal dilation of the distal ulnar artery. An incidence of 1.6% has been reported in a large cohort study of 1300 patients.¹ These vascular lesions appear to be commonly caused by repetitive blunt trauma to the hypothenar eminence where the ulnar artery is superficial as it passes through Guyon’s canal.^1-4 Patients suffer from a variety of symptoms such as cold intolerance, pain, paresthesias, and digital discoloration, primarily of the ring and small fingers.^2,3 Severe disease can result in ulceration and necrosis of the ulnar digits.

Treatment options for this condition range from conservative management to surgical intervention. Surgical options include resection of the arterial segment with: (1) vessel ligation; (2) vascular reconstruction with direct end-to-end anastomosis; or (3) vascular reconstruction with interposition vein graft or arterial conduit. However, there is no consensus on the optimal surgical management, and there are few studies evaluating the long-term outcomes of these procedures. Current literature consists of studies limited to small cohorts, mostly assessing the efficacy of 1 or 2 surgical techniques.^5,6

To this end, the aim of this study was to describe the long-term patient-reported outcomes in patients who underwent resection or vascular reconstruction of the ulnar artery for HTHS. In addition, we evaluated what factors influence patient-reported outcomes.

Methods

This retrospective study was conducted at a single institutional system after approval by the local institutional review board. To identify patients, we used Current Procedural Technology (CPT) codes and International Classification of Diseases (ICD), Ninth and Tenth Revision procedure codes that coded for vascular surgery of the ulnar artery (Appendix A). These results were cross-matched with ICD-9 and ICD-10 diagnoses codes (Appendix B) that coded for HTHS to create a cohort with patients who potentially underwent surgical intervention for HTHS. Electronic medical records were reviewed to verify which patients met inclusion criteria. All patients who underwent pseudoaneurysm excision or vascular reconstruction of the ulnar artery for HTHS from January 2002 to March 2016 were included. Patients who were <18 years old, pregnant, or had an ulnar artery laceration were excluded.

To evaluate long-term outcomes, all living patients (n = 25) were contacted by mail and then by telephone to complete outcome questionnaires. Fifteen patients (56%) agreed to complete the questionnaires, 4 (16%) declined to participate, and 6 (24%) could not be contacted. Two patients were deceased at the time this study was conducted. Study data were collected and managed using REDCap (Research Electronic Data Capture) electronic data capture tools hosted at our institutional system. REDCap is a secure, web-based application designed to support data capture for research studies, providing: (1) an intuitive interface for validated data entry; (2) audit trails for tracking data manipulation and export procedures; (3) automated export procedures for seamless data downloads to common statistical packages; and (4) procedures for importing data from external sources.

Patient characteristics were collected through manual chart review and included demographics (age, sex, race, occupation), comorbidities (smoking status, diabetes mellitus), presence of preoperative trauma, workers’ compensation status, hand affected (dominant vs nondominant), preoperative angiography results, and type of surgery (excision ligation vs direct repair with end-to-end anastomosis vs reversed vein graft). In addition, we collected information on postoperative symptoms, complications, and reoperations. A reoperation was defined as an unplanned surgery of the ulnar artery after initial surgery.

Demographics

Twenty-seven patients with surgically treated HTHS were identified in the coding search. Fifteen patients met inclusion criteria and completed questionnaires. The average age was 48.4 ± 8 years, and the majority of the patients were men (14/15, 93%) and Caucasian (14/14, 100%; for 1 patient no race was recorded) (Table 1). The median chart follow-up time was 3.1 months (interquartile range [IQR], 0.9-19.3), and the median questionnaire follow-up was 7.2 years (IQR, 3.1-9.9).

Table 1.

Demographics.

Patient characteristics	Total cohort (n = 15)
Age, mean (SD)	48.4 (8)
Male, No. (%)	14 (93)
Caucasian, No. (%)	14 (100)a
Dominant hand affected, No. (%)	9 (60)
Smoker, No. (%)	1 (7)
Diabetes, No. (%)	1 (7)
Preoperative trauma, No. (%)	11 (73)
Manual labor occupation, No. (%)	7 (47)
Workers’ compensation, No. (%)	2 (13)
Preoperative angiography, No. (%)
Occlusion	7 (50)a
Corkscrew/vessel irregularity	5 (36)a
Aneurysm	1 (14)a
Surgery type, No. (%)
Excision ligation	3 (20)
Direct repair	5 (33)
Reversed vein graft	7 (47)

^an = 14.

Most patients (9/15, 60%) had HTHS of their dominant hand, and the most common symptoms were pain (11/14, 79%), sensory changes (numbness and/or paresthesias) (9/14, 64%), and cold intolerance (7/14, 57%). A minority of patients (2/14, 14%) experienced distal digital ulceration. Symptoms most commonly presented in the fourth (10/14, 71%) and fifth (10/14, 71%) digits. While many (11/15, 73%) patients had a history of preceding hand trauma, only 7 patients (47%) worked at jobs requiring manual labor. One patient (7%) had a history of cigarette smoking and one (7%) had a history of diabetes mellitus (Table 2). Preoperative physical examination elicited a positive Allen test in most patients (9/10, 90%) but revealed a palpable mass in only a minority (2/14,14%) of patients. Preoperative imaging was performed with arteriography (6/14, 43%), magnetic resonance angiography (6/14, 43%), and computed tomographic angiography (1/14, 7%). For 1 patient (7%), angiography results were recorded in physician notes, but type of angiography was not specified. One patient did not have any record of angiography. Preoperative radiology demonstrated ulnar artery occlusions (7/14, 50%; Figure 1), ulnar artery irregularities/corkscrew appearances (5/14, 36%; Figure 2), and ulnar artery aneurysms (1/14, 14%; Figure 3).

Table 2.

Demographics and Clinical Characteristics of Patients With Long-term Outcome Data.

Patient	Age, y	Sex	Dominant hand affected	Smoker	Preoperative trauma	Occupation	Surgery	RVG length (cm)	Postoperative complication	F/u, y	Symptom outcome	Initial symptoms (bold = symptoms remaining postoperatively)	Fingers affected	Quick DASH	CISS	PROMIS UE	PROMIS Pain Interference
1	41	M	R/R	No	Crush injury	Baggage handler	EL	—	Infection	9.9	Improvement	Cold intol., pain, numbness	4+5	5	58	61	39
2	54	M	R/R	No	Wrench use	Disabled (unrelated)	EL	—	Infection	2.7	Improvement	Cold intol., pain, paresthesias, cyanosis, ulcers	2,3,4,5	39	59	37	60
3	55	M	R/R	No	Manual labor	Contractor	EL	—	No	8.3	No improvement	Cold intol., pain, numbness	—	2	15	61	39
4	45	M	R/L	No	Jackhammer use	Steel worker	DR	—	No	16.0	Full resolution	Cold intol., pain, paresthesias	2+3	7	24	40	48
5	40	M	R/L	No	None	Physician	DR	—	No	2.1	Full resolution	Numbness, paresthesias	4+5	5	4	61	39
6	45	M	R/L	No	None	Bartender	DR	—	No	12.0	Resolution > Recurrence	Cold intol., pain, paresthesias, cyanosis	4+5	2	21	61	50
7	57	M	R/L	No	Bicycling	Physician	DR	—	No	2.2	Full resolution	Pain, numbness, paresthesias	4+5	0	4	61	39
8	51	M	R/L	No	None	School principal	DR	—	No	3.9	Improvement	Cold intol., pain, numbness	3	2	22	61	39
9	69	M	R/R	No	Pickaxe use	Carpentry teacher	RVG	13	No	7.6	Improvement	Pain, paresthesias	4+5	36	50	46	39
10	55	M	R/L	No	Fall onto wrist	Gym teacher	RVG	4	No	9.0	Full resolution	Pain, pallor, cyanosis (4+5)	4+5	0	4	61	39
11	44	M	R/R	Yes	Acute blow to hand	Service Technician	RVG	3	No	3.1	No improvement	Cold intol., pain, paresthesias, cynosis, ulcers	3,4,5	7	61	46	53
12	39	M	R/R	No	Screwdriver use	Locksmith	RVG	3	No	7.2	Full resolution	Cold intol., pain, palpable mass	2,3,4,5	—	—	—	—
13	48	M	L/L	No	Hand as hammer	Carpenter	RVG	10	No	7.1	Improvement	Cold intol., numbness, paresthesias	4+5	23	35	48	53
14	48	M	R/R	No	Hand as hammer	Disabled (unrelated)	RVG	Unknown	No	14.3	Improvement	Cold intol.	2,3,4,5	36	27	45	55
15	59	F	R/R	No	None	Retired	RVG	2.5	No	6.6	Full resolution	Palpable mass	—	0	4	61	39

Note. RVG = reversed vein graft; F/u = follow-up; DASH = Disabilities of the Arm, Shoulder, and Hand; CISS = Cold Intolerance Symptom Severity; PROMIS UE = Patient-Reported Outcomes Measurement Information System Upper Extremity; DR = direct repair; EL = excision ligation; cold intol. = cold intolerance.

Figure 1.

Arteriogram demonstrating occlusion of ulnar artery.

Figure 2.

Arteriogram demonstrating corkscrew appearance of ulnar artery (encircled).

Figure 3.

Arteriogram demonstrating aneurysm of ulnar artery (encircled).

Surgical treatment included ulnar artery excision with reversed vein graft reconstruction in 7 (47%) patients, excision with direct repair of the ulnar artery in 5 (33%) patients, and excision with ligation of the ulnar artery in 3 (20%) patients. For patients who underwent reversed vein graft reconstruction, the median vein graft length was 3.5 cm (IQR, 3-10).

Patient-Reported Outcomes

Patients were asked to complete the following questionnaires: (1) Quick Disabilities of the Arm, Shoulder, and Hand (Quick DASH); (2) Cold Intolerance Symptom Severity (CISS) survey; (3) Patient-Reported Outcomes Measurement Information System Upper Extremity Computer Adaptive Test (PROMIS UE CAT); (4) Patient-Reported Outcomes Measurement Information System Pain Interference Computer Adaptive Test (PROMIS Pain Interference CAT); and (5) Hypothenar Hammer Syndrome–specific questionnaire developed by the study authors (Appendix C). One patient only completed the HTHS-specific questionnaire, while the other 14 patients completed all 5 questionnaires (Table 3).

Table 3.

Patient-Reported Outcomes.

	qDASH	CISS	PROMIS Upper Extremity	PROMIS Pain Interference
	Median (IQR)	Mean (SD)	Mean (SD)	Mean (SD)
All patients (n = 14)	4.5 (2.3-22.7)	27.7 (21.6)	53.5 (9.4)	44.8 (7.8)
Surgery
Excision and ligation (n = 3)	4.5 (2.3-38.6)	44 (25.1)	53.0 (13.9)	45.9 (12.5)
Direct repair (n = 5)	2.3 (2.3-4.5)	15 (10.1)	56.7 (9.6)	42.7 (5.6)
Vein graft (n = 6)	14.8 (0-36.4)	30.2 (23.4)	51.1 (7.7)	46.0 (8.0)
P value	.52a	.18b	.65b	.79b
Dominant hand operated
Yes (n = 8)	14.8 (3.4-36.4)	38.6 (21.8)	50.6 (9.2)	46.9 (9.0)
No (n = 6)	2.27 (0-4.5)	13.2 (10.1)	57.4 (8.8)	42.1 (5.3)
P value	.07c	.022d	.19d	.27d
Manual Labor job
Yes (n = 6)	6.8 (4.5-22.7)	40.5 (18.8)	50.1 (8.9)	44.8 (6.9)
No (n = 8)	2.27 (0-20.45)	18.1 (19.2)	56.0 (9.5)	44.8 (8.9)
P value	.19c	.050d	.26d	.10d

Note. qDASH = Quick Disabilities of the Arm, Shoulder, and Hand; CISS = Cold Intolerance Symptom Severity; PROMIS = Patient-Reported Outcomes Measurement Information System; IQR = interquartile range. Bold indicates statistical significance <0.05.

^aUsing Kruskal-Wallis test.

^bAnalysis of variance.

^cMann-Whitney U test.

^dStudent t test.

Statistical Analysis

We performed bivariate analyses to evaluate whether long-term patient-reported outcomes were affected by type of surgery, surgery of the dominant hand, or patient employment requiring manual labor. Only these variables were included in analysis because the size of these groups allowed for statistical analysis. We used the analysis of variance and Student t test for parametric continuous variables and Kruskal-Wallis and Mann-Whitney U test for nonparametric continuous variables. Statistical significance was defined as P < .05 for all tests. We performed a correlation to evaluate whether manual labor occupation and surgery of the dominant hand were correlated.

Results

The median Quick DASH score was 4.5 (IQR, 2.3-22.7), the mean CISS was 27.7 ± 21.6, the mean PROMIS UE score was 53.5 ± 9.4, and the mean PROMIS Pain Interference score was 44.8 ± 7.8. All scores were similar across surgery groups. Higher CISS scores were associated with surgery of the dominant hand (13.2 vs 38.6, P = .022) and having a job involving manual labor (18.1 vs 40.5, P = .050). There was no correlation between surgery of the dominant hand and having a manual labor job (r = 0.33).

Six (40%) patients experienced complete symptom resolution, 6 (40%) had improvement without complete symptom resolution, 1 (7%) had complete symptom resolution followed by recurrence of symptoms at 7 years, and 2 (13%) reported no postoperative improvement. The most common symptom after surgical intervention was cold intolerance (reported by 8 of 9 patients with persistent symptoms). Two patients (13%) had postoperative infections that were successfully treated with antibiotics. There were no other postoperative complications, and there were no reoperations on the ulnar artery.

Discussion

This study evaluated patient-reported outcomes in 15 patients who underwent surgery for HTHS with a median follow-up of 7.2 years. We found that surgical intervention for HTHS results in favorable patient-reported outcomes, and no patient underwent reoperation on the ulnar artery. Although 9 of 15 (60%) patients reported persistent postoperative symptoms, these symptoms did not seem to substantially limit long-term function as measured by the Quick DASH, PROMIS UE CAT, and PROMIS Pain Interference CAT. In addition, involvement of the dominant hand and having a manual labor occupation were associated with more postoperative symptoms of cold intolerance.

The median Quick DASH score of 4.5 in this study suggests limited postoperative functional disability.⁷ These functional outcomes are similar to those found by Endress et al who reported average DASH scores of 0 and 8 in patent and occluded ulnar artery reconstructions, respectively.⁵ In contrast, Kitzinger et al reported higher DASH scores of 16.1 on average in patients with patent ulnar arteries.⁶ Their cohort consisted entirely of manual laborers, whereas our cohort consisted of only 47% of manual laborers. Our findings of 40% of complete symptom resolution, 47% of partial symptom resolution or symptom recurrence, and 13% of no improvement are consistent with the findings of a systematic review by Vartija et al.⁸

The PROMIS UE mean of 53.5 in this study suggests minimal functional impairment, and the PROMIS Pain Interference mean of 44.8 represents a mild impairment. Furthermore, the average CISS score of 27.7 suggests limited postoperative cold intolerance symptoms, as the cutoff for pathologic cold intolerance has been suggested to be 30 (the upper 95% confidence interval in healthy patients).⁹ This finding is particularly notable as our institution is in an area with a substantial winter season. One might expect CISS scores to be worse than PROMIS scores in colder climates and similar to PROMIS scores in warmer climates, but in our study, both PROMIS and CISS scores demonstrated limited postoperative impairment, despite the cool climate of our region.

Men in their fourth and fifth decades comprised the majority of this study cohort, which is comparable to the previous literature on HTHS.^{1,5,6,8,10,11} However, patients in our study had fewer documented comorbidities, and there was a smaller fraction of manual laborers compared with patients in prior studies.^2,6 In addition, although arterial reconstruction has gained momentum since it was proposed by Smith et al in 2004, the majority of patients in this study underwent a vein graft reconstruction of the ulnar artery, and there were no arterial reconstructions performed at our institution during the study period.^10,12,13 It is notable that of the patients who underwent vein graft reconstruction, the only patient to experience no symptomatic improvement was the only smoker in the cohort. Although the small size of the study cohort limits further analysis, this observation supports the notion that smoking cessation is an essential aspect of treatment for this condition.

Overall, in this study, the finding that dominant hand involvement and manual labor occupations are associated with worse cold intolerance symptoms after surgery suggests that hand use is the major variable that influences outcomes. This study has several limitations. First, we had a small cohort of patients, which increases the possibility of type 2 statistical error in our analyses. Given the small size of the study population, it was not possible to evaluate the influence of all factors on patient-reported outcomes, and we could not correct for potential confounders such as age, gender, smoking, and diabetes mellitus. Second, only 15 of the 25 living patients (60%) agreed to participate, and their outcomes may differ from the patients who either declined or were unable to be contacted. Third, we could not account for selection bias, as treatment decisions were made on a patient-to-patient basis given surgeon preference. For instance, prior literature has recommended initial conservative management with interventions such as smoking cessation and trauma avoidance,^4,8 but it is unknown whether some surgeons advocate for earlier surgical intervention relative to others in the cohort. Strengths of this study include the duration of follow-up, the completeness of information found in the electronic medical record, and the evaluation of select patient factors predicting postoperative outcomes.

We did not assess patency of the reconstructions in our study; however, the importance of ulnar artery patency and its influence on functional outcomes is disputed.^5,6,10,14 Both Endress et al⁵ and Kitzinger et al⁶ found no statistical difference in DASH scores between patients with occluded and patent grafts at long-term follow-up, whereas Lifchez and Higgins14 suggested a trend toward better functional outcomes with graft patency but did not find a significant association. In addition, Endress et al⁵ report that patients with patent grafts had significantly fewer symptoms of cold intolerance.

In conclusion, patient-reported outcomes after surgical intervention for HTHS are modest and treatment of manual laborers and of the dominant hand is associated with inferior cold intolerance. Patient-reported outcomes are consistent across excision ligation, direct repair, and vascular reconstruction with vein graft, suggesting that all 3 surgical interventions produce similar symptomatic improvements. The most common persistent symptom after surgical intervention is cold intolerance, but its persistence neither influences patient-reported outcomes nor leads to reoperation. Manual labor and surgery of the dominant hand are associated with worse postoperative cold intolerance symptoms.