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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 33  |  Issue : 4  |  Page : 1341-1346

Hypothenar Island flap: a safe and excellent choice for little finger defects


1 Department of Plastic Surgery, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Plastic Surgery, Helmia Military Hospital, Cairo, Egypt

Date of Submission29-Mar-2020
Date of Decision01-Jun-2020
Date of Acceptance06-Jun-2020
Date of Web Publication24-Dec-2020

Correspondence Address:
Ahmed M Harfoush
Nasr City, Cairo Governorate
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_110_20

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  Abstract 


Objective
The aim was to evaluate the functional and cosmetic results of hypothenar island flap for the reconstruction of little finger defects and to assess them by follow-up.
Background
Reconstruction of soft-tissue defects of little finger of the hand needs a single-stage procedure that can provide well-vascularized coverage at the earliest stage to give the best functional result.
Patients and methods
This follow-up study that included 19 patients (13 men and six women) was carried out in the Plastic and Reconstructive Surgery Departments of Menoufia University and Helmia Military Hospital from October 2017 to October 2019, with assessment by a follow-up period of 12 months and physiotherapy. All the patients studied had the hypothenar island flap for coverage of the defects. The defects were due to postblunt trauma in three cases, post-burn in three cases, and post-sharp trauma in 13 cases. The largest flap was 20 × 15 mm2. The donor site was directly closed in all cases.
Results
The overall results were satisfactory regarding the function and appearance without major complications according to patient and doctor satisfaction. Regarding flap course and survival, 14 (73.7%) flaps passed uneventfully, five (26.3%) flaps suffered from venous congestion, five congested flaps survived without total loss and only partial loss and thus we had 19 (100%) survived flaps.
Conclusion
Hypothenar island flap is a reliable and versatile source for coverage of soft-tissue defects of little finger of the hand.

Keywords: flap, hypothenar, island, little finger, reconstruction, reversal artery


How to cite this article:
Keshk TF, El Kashty SM, Harfoush AM. Hypothenar Island flap: a safe and excellent choice for little finger defects. Menoufia Med J 2020;33:1341-6

How to cite this URL:
Keshk TF, El Kashty SM, Harfoush AM. Hypothenar Island flap: a safe and excellent choice for little finger defects. Menoufia Med J [serial online] 2020 [cited 2021 Apr 19];33:1341-6. Available from: http://www.mmj.eg.net/text.asp?2020/33/4/1341/304473




  Introduction Top


The hand is an intricate part of the body that plays an essential role in social functioning, expression, productivity, and interactions with our environment[1]. So reconstruction of soft-tissue defects of the little finger is a challenging problem[2]. So the reconstructive needs are to provide stable coverage and sensibility. A functional fifth metacarpal bone and functional ulnar fingers are important for the locking grip and supporting grip[3]. And the ulnar two digits play a significant role in the overall grip strength of the entire hand. Exclusion of the ulnar two digits resulted in a 34–67% decrease in grip strength, with a mean decrease of 55%. Exclusion of the little finger from a functional grip pattern decreased the overall grip strength by 33%. Exclusion of the ring finger from a functional grip pattern decreased the overall grip strength by 21%. It is clear that limitation of one or both of the ulnar digits adversely affects the strength of the hand[4]. But skin/soft-tissue envelope of the hand is a complex structure that not only covers the underlying structures, but also has specialized functional and sensory components. The thick glabrous skin of the palm withstands shearing forces encountered during daily activities and provides discriminatory sensory function that transfers touch, pain, and temperature, whereas the dorsal skin is pliable and mobile that permits a wide range of motion of the hand such as fingers pinch and grip[1]. Usually soft-tissue defects of the hand following trauma or tumor resection are frequently encountered in hand surgery and may result in a temporary or permanent disability if not managed appropriately[1]. Over the past decades, several reconstructive procedures and their modifications had evolved to provide the ideal soft tissue coverage of the hand[1]. Conventionally, these included a range of options of primary wound closure, skin grafts, local flaps, distant flaps, and microvascular free tissue transfer[1]. However, selecting the most suitable type of soft tissue cover for a particular defect can be a challenging process. Furthermore, the abundance of currently available reconstructive techniques makes this task rather difficult, especially for the inexperienced surgeon. When choosing one reconstructive method over the other, it is prudent that the surgeon has a sound knowledge of all available options, their limitations, complications, and expected outcomes. Reconstruction algorithms such as the reconstructive ladder, reconstructive elevator, and reconstructive matrix have been devised to assist surgeons in determining the most appropriate type of soft-tissue reconstruction[1]. Although sometimes useful, there is no simple schema for reconstruction as every injury is different and every patient has a unique set of medical conditions. But the reverse digital artery island flap is a safe and reliable procedure with a high survival rate[5]. And the hypothenar area is used as a vascularized flap donor site very infrequently in clinical practice[6]. Also it has a significant sensory potential for finger reconstruction[6]. So instead of revision amputation or weak local flap with donor site morbidity, we can use this reliable and easy flap for coverage of little finger with direct closure of donor site with no morbidity[7]. The aim of this study was to evaluate the functional and cosmetic results of hypothenar island flap for the reconstruction of little finger defects and to assess them by follow-up.


  Patients and Methods Top


This prospective study was conducted at The Department of Plastic and Reconstructive Surgery, Menoufia University Hospitals and Helmia Military Hospital. It was conducted in the period from October 2017 to October 2019 with a follow-up period of more than 1 year in some cases. The study was approved by the Ethics Committee of Menoufia Faculty of Medicine and Helmia Military Hospital. All participants gave written informed consent before inclusion into the study. Patients underwent hypothenar island flap for the management of soft tissue defects in the little finger. The cause of defect wound varied from trauma, infection, or burn which occurs accidently with no evidence of child abuse, suicidal, or homicidal attempts for all patients.

Inclusion criteria

Soft-tissue defects in the little finger due to any etiological cause. All patients had intact hypothenar area. The age of patients is above 4 years (for possible pedicle dissection).

Exclusion criteria

Critically ill patients who cannot tolerate anesthesia and operation. Patients with damaged hypothenar skin. Patients who refuse operation. Patients with systemic diseases such as diabetes, ischemic vascular disease, atherosclerosis, and autoimmune vascular disease are excluded to avoid the possibility of peripheral vascular injury and their effects on blood flow to the flap.

Admitted patients

For all the patients the following hospital data were obtained: operative details, operative time, photographs (preoperative, intraoperative, postoperative), benefits of the operative procedure, and operative complications including wound infection, flap loss, and flap congestion).

Preoperative preparation

Preoperatively, all patients were evaluated generally and locally before the operation. Anesthesia consultation was carried out for each patient. Full laboratory investigations were done including complete blood count, blood grouping, fasting and postprandial blood sugar, albumin and liver functions tests, kidney functions tests, and coagulation profile.

Methods

All patients were subjected to history taking, general and local examination of the hand, and defect examination: shape, site, size, component (bone, muscles, soft tissues, neurovascular element), and consistency. Hand examinations included motor and sensory investigations were carried out for the lesion for functional and cosmetic defects, photographic documentation, and physiotherapy.

Operative technique

The patient was prepared in the supine position and then marking of the flap proximal to A1 pulley where perforators come from ulnar digital artery and go through layers of the skin at this area [Figure 1]. Under general anesthesia, wrist block, or local intravenous anesthesia , sterilization of the wound was done. Tourniquet should be used around the ipsilateral arm to provide easy, bloodless dissection of the flap. Defect is debrided and prepared for flap coverage. Flap dissection is performed in the subfascial plane of the medial side of the abductor digiti minimi muscle. Multiple perforating branches running transversely and arising from the ulnar palmar digital artery are identified. After ligating the ulnar palmar digital artery and concomitant veins at the proximal side of the flap, they are retrogradely dissected at the distal point of rotation which supplies reverse flow of the flap. The distal point of rotation is the neck of the proximal phalanx, which is related to the proximal transverse palmar perforators between the ulnar and radial palmar arteries. A perivascular cuff of tissue is preserved that aids in venous drainage. We consider that is unsafe to pass the pedicle under a tunnel, so we recommend a Brunner incision from the donor site to the defect. The donor site is closed primarily [Figure 1]. The flap is suitable for defects of the little finger whatever the cause, trauma or post-burn contractures [Figure 2] and [Figure 3].
Figure 1: (a) Preoperative photograph of the posttraumatic defect of the volar aspect of the left little finger and the flap design: the island skin is marked proximal to the thenar crease. (b) After ligating the ulnar palmar digital artery and concomitant veins at the proximal side of the flap, they are retrogradely dissected at the distal point of rotation which supplies reverse flow of the flap. (c) The distal point of rotation is the neck of the proximal phalanx, which is related to the proximal transverse palmar arch between the ulnar and radial palmar arteries. (d) A perivascular cuff of the tissue is preserved that aids in venous drainage. We consider that is unsafe to pass the pedicle under a tunnel, so we recommend a Brunner incision from the donor site to the defect. (e) The donor site is closed primarily.

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Figure 2: (a) Male patient of 21 years old presented with post-traumatic gangrenous distal tip little finger, managed with hypothenar island flap: (a) preoperative distal tip little gangrene, (b) after amputation of distal part and marking of flap, (c) elevation of the flap, (d) release of tourniquet and good perfusion of the flap, (e) reversed setting of the flap, (f) closure of skin, (g) 2 weeks postoperatively.

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Figure 3: (a) Female patient 25 years old presented with post-burn flexion deformity little finger, released with hypothenar island flap: (a) preoperative, (b) elevation of the flap, (c) reversed setting of the flap, (d) closure of defect and donor site and fixation of little finger by k wire.

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Data management and statistical analysis

All data were collected, tabulated, and statistically analyzed. The descriptive measures of central tendency (mean and median) and measures of dispersion (range, SD, minimum, and maximum), besides frequency and the percentage, were calculated by SPSS 20 statistical software package (SPSS Inc., Chicago, Illinois, USA).

χ2-test was used in the comparison between two groups with qualitative data and Fisher's exact test was used instead of the χ2 test when the expected count in any cell is found to be less than 5. The confidence interval was set to 95% and the margin of error accepted was set to 5%. So, a P value of less than 0.05 was considered statistically significant.


  Results Top


This study included 19 patients, with 13 (68.4%) men and six (31.6%) women. All presented with post-traumatic little finger defects. Age of patients ranged from 12 to 33 years, mean of age was 23.26 [Table 1]. All defects of little finger were post-traumatic, three (15.8%) cases were of post-blunt trauma, three (15.8%) cases were of post-burn, and 13 (68.4%) cases were of post-sharp trauma. Size of defects ranged from 12 × 12 mm (15.8%) to 20 × 13 mm (15.8%), and size of the flap taken ranged from 15 × 10 mm (10.5%) to 20 × 15 mm (42.1%). Fourteen (73.7%) flaps passed uneventfully, five (26.3%) flaps suffered from venous congestion, five congested flaps survived without total loss, only partial loss, and thus we had 19 (100%) survived flaps [Table 2]. The mean of HB was 12.83 with range from 11 to 15; mean of international normalized ratio was 1.03 with range from 0.9 to 1.1. The mean of hospital stay was 3.89 with range from 2 to 10; the mean of two-point discrimination sensation postoperatively was 6.79 with range from 5 to 8 [Table 3]. As regards donor site morbidity, it was closed directly in all cases, so there was no functional deformity, and the subjective aesthetic result, according to the patients, was satisfactory in 100% of the patients . Measurments of flaps were taken more than defects measurements. This helps suitable range of movements and adequate cover with early regain of function of finger.
Table 1: Results regarding the relation between sex and age of the studied patients

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Table 2: Results regarding defect, flap sizes, and early postoperative complications

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Table 3: Results regarding preoperative laboratories, post-operative hospital stay, and two-point discrimination of studied patients

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  Discussion Top


The hand is an intricate part of the body that plays an essential role in social functioning, expression, productivity, and interactions with our environment[8]. Upper extremity soft-tissue reconstruction is an extensive topic as a multitude of options exist for diverse soft-tissue defects involving the shoulder, arm, elbow, forearm, wrist, and the hand. Many of the times flap cover is necessary for resurfacing exposed critical structures like tendons, neurovascular structures, bone and to provide supple tissue over joints. According to Naalla et al.[9] skin/soft-tissue envelope of the hand is a complex structure that not only covers the underlying structures but also has specialized functional and sensory components[1]. Soft-tissue defects of the hand following trauma or tumor resection are frequently encountered in hand surgery and may result in a temporary or permanent disability if not managed appropriately. Over the past decades, several reconstructive procedures and their modifications have evolved to provide the ideal soft-tissue coverage of the hand[1]. there is a wide range of options of primary wound closure, skin grafts, local flaps, distant flaps, and micro-vascular free tissue transfer. However, selecting the most suitable type of soft-tissue cover for a particular defect can be a challenging process[10]. If there are no specific contraindications for local skin flaps such as crush injuries or the presence of local infection, they should be considered as the first line of treatment[11]. Different regions of the hand have different functional and aesthetic requirements. For example, reconstructing highly sensate areas such as the fingertips with non-sensate skin may cripple the entire function of a patient's hand. On the other hand, transposing skin containing hair follicles to a hairless surface such as the palm would result in poor aesthetic appearance and patient dissatisfaction with surgery[12]. Skin grafts require a vascularized wound bed for the graft to take and are not suitable to cover defects over exposed tendons or bones without paratenon or periosteoum. Furthermore, the high contracture potential, limited scar pliability, and poor sensibility limit their successful use as a primary method of reconstruction in the hand[1].Digital soft-tissue reconstruction has been developed using the knowledge of the small digital arteries and the different angiosomes located on specific zones of the hand[6]. The rich vascular network of the hypothenar region has raised the interest of several authors, who explored its potential as the donor site for local or free flap for hand defect coverage[13]. Primary closure of the donor site is an advantage compared with many other homodigital flaps. The Allen test is necessary because the ulnar palmar digital vessel is divided at the proximal end and vascularity of the finger entirely depends on the integrity of radial digital vessel[6]. The location of the perforator at the posteromedial aspect of the hand is consistent; the ulnar palmar perforator flap is particularly suitable to cover defects in the little finger or the ulnar aspect of hand. But ulnar palmar perforator flap cannot reach the distal level of the little finger[14]. A reverse island flap from the hypothenar eminence is easily elevated, contains durable fasciocutaneous structures, and has a good color and texture matching the finger pulp. This flap is a good alternative for the reconstruction of palmar skin and soft-tissue defects of the little finger. Omokawa et al. recommended that subfascial dissection of the flap should be performed from the dorsal side of the hand[15]. However, in our study, flap dissection is performed in the subfascial plane of the medial side of the abductor digiti minimi muscle. Wolff et al.[16] stated that venous congestion is a disadvantage of the hypothenar island flap. Hao et al.[14] reported that all the flaps survived without complications. Tapan et al.[6] reported that all the flaps survived without arterial and venous insufficiency. In our study, all the flaps survived with venous congestion and partial flab loss presented in only five cases represented 26.3% of our cases. Rest of cases passed without any complications representing 73.7% of our cases. The ability to predict hand function based on the degree of sensory impairment is required in determining disability rating and evaluating patients for reconstructive surgery[17]. The absolute contraindication for using this flap is severe injury to the little finger with vascular compromise of the digits or critically ill patients who cannot tolerate anesthesia and operation. Other relative contraindications are elderly patients or those suffering from vascular diseases or patients with systemic diseases such as diabetes, ischemic vascular disease, atherosclerosis, and autoimmune vascular disease are excluded to avoid possibility of peripheral vascular injury and their effects on the blood flow to the flap, and patients who refuse operation. The success of flap survival of our study can be related to the age group of the patients that range from 12 to 33 years with a mean of age 23.26. None of the patients has vascular diseases or any chronic illness with preoperative basic investigations within normal ranges. We used the modified American Society for Surgery of the Hand guidelines to stratify the 2 PD measurements (excellent, ≤6 mm; good, 6–10 mm; fair, 11–15 mm; poor, ≥15 mm)[17]. The potential disadvantages of the hypothenar flap are contracture and limited extension of little finger because of continuous incisions of palmar side of the hand. Scar massage and range of motion exercises are effective in the postoperative period. Patient compliance with rehabilitation is an important part of the treatment. We consider that is unsafe to pass the pedicle under a tunnel, so we recommend a Brunner incision from the donor site to the defect. The donor site is closed primarily.


  Conclusion Top


Soft-tissue defects of the hand commonly arise as a consequence of trauma or infection and after resection of tumors. Restoring a thin and pliable soft tissue envelope is critical to restoring mobility and optimizing functional outcomes. The appearance, color, and texture match as well as donor site issues are increasingly important aspects of hand reconstruction. Soft-tissue defects of the little finger are challenging especially when the bone, tendon, or the vascular pedicle is exposed because of trauma. The reverse digital artery island flap is a safe and reliable procedure with a high survival rate. The hypothenar area is used as a vascularized flap donor site very infrequently in clinical practice. The hypothenar area has significant sensory potential for finger reconstruction. A reverse island flap from the hypothenar eminence is easily elevated, contains durable fasciocutaneous structures, and has a good color and texture match to the finger pulp. This flap is a good alternative for the reconstruction of the palmar skin and soft-tissue defects of the little finger.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Rehim SA, Chung KC. Local flaps of the hand. Hand Clin 2014; 30:137–151.  Back to cited text no. 1
    
2.
Hariharan N, Sridhar R, Sankari B, Valarmathy V, Asirvatham E, Geetha K. Reconstruction of postburn crippled hands: a study of functional outcome. Indian J Burn 2018; 26:7–9.  Back to cited text no. 2
    
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Kollitz KM, Hammert WC, Vedder NB, Huang JI. Metacarpal fractures: treatment and complications. Hand 2014; 9:16–23.  Back to cited text no. 3
    
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Methot J, Chinchalkar SJ, Richards RS. Contribution of the ulnar digits to grip strength. Can J Plast Surg 2010; 18:10–14.  Back to cited text no. 4
    
5.
Matsui J, Piper S, Boyer MI. Nonmicrosurgical options for soft tissue reconstruction of the hand. Curr Rev Musculoskelet Med 2014; 7:68–75.  Back to cited text no. 5
    
6.
Tapan M, İğde M, Yıldırım AR, Balı YY, Yılancı S, Ünlü RE. Hypothenar island flap: a safe and excellent choice for little finger defects. Indian J Plast Surg 2015; 48:286–288.  Back to cited text no. 6
    
7.
Pirlich M, Horn IS, Mozet C, Dietz A, Fischer M. Functional and cosmetic donor site morbidity of the radial forearm-free flap: comparison of two different coverage techniques. Eur Arch Otorhinolaryngol 2018; 275:1219–1225.  Back to cited text no. 7
    
8.
Hegge T, Henderson M, Amalfi A, Bueno RA, Neumeister MW. Scar contractures of the hand. Clin Plast Surg 2011; 38:591–606.  Back to cited text no. 8
    
9.
Naalla R, Chauhan S, Dave A, Singhal M. Reconstruction of post-traumatic upper extremity soft tissue defects with pedicled flaps: an algorithmic approach to clinical decision making. Chin J Traumatol 2018; 21:338–351.  Back to cited text no. 9
    
10.
Grigorescu D, Biris S, Vaidahazan R, Corâiu C, Sav F, Cîmpeanu C. Posibilitati Si Limite În Rezolvarea Defectelor De Parti Moi La Nivelul Razelor Digitale 2-5 Ale Mâinii/Possibilities And Limits In Solving The Soft Tissues Defects Of The Hand Fingers (2-5). J Med Brasovean 2016; 1:21–23.  Back to cited text no. 10
    
11.
Foucher G, Boulas HJ, Da Silva JB. The use of flaps in the treatment of fingertip injuries. World J Surg 1991; 15:458–462.  Back to cited text no. 11
    
12.
Giessler GA, Erdmann D, Germann G. Soft tissue coverage in devastating hand injuries. Hand Clin 2003; 19:63–71.  Back to cited text no. 12
    
13.
Toia F, Marchese M, Boniforti B, Tos P, Delcroix L. The little finger ulnar palmar digital artery perforator flap: anatomical basis. Surg Radiol Anat 2013; 35:737–740.  Back to cited text no. 13
    
14.
Hao PD, Zhuang YH, Zheng HP, Yang XD, Lin J, Zhang CL, et al. The ulnar palmar perforator flap: anatomical study and clinical application. J Plast Reconstruct Aesth Surg 2014; 67:600–606.  Back to cited text no. 14
    
15.
Omokawa S, Yajima H, Inada Y, Fukui A, Tamai S. A reverse ulnar hypothenar flap for finger reconstruction. Plast Reconstr Surg 2000; 106:828–833.  Back to cited text no. 15
    
16.
Wolff GA, Patrón AS, Herrera O, Posso C. Reconstruction of volar digital defects: clinical experience with the hipothenar flap. Techniques 2010; 3:33–39.  Back to cited text no. 16
    
17.
Dellon AL, Kallman CH. Evaluation of functional sensation in the hand. J Hand Surg 1983; 8:865–870.  Back to cited text no. 17
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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