INTRODUCTION

 

Traumatic amputation of the tip of the finger is a common injury both in domestic and industrial settings ⁽¹⁾. Finger tip amputation is the most common type of amputation injury in the upper extremity ⁽²⁾. The finger tip is defined as the portion of the finger distal to the plane of the major dorsal and volar skin creases at the distal interphalyngeal joint ⁽³⁾.

The two-point discrimination test is the most frequently used test for the assessment of the sensory outcome after nerve repair ⁽⁴⁾. For dermatomal regions of the arm and forearm, mean values ranged from 30.7 mm to 45.4 mm. In the hand, the skin overlying the first dorsal interosseous muscle demonstrated discrimination values of 21.0 mm while that covering the volar surface of the tips of the thumb and long and little fingers showed values of 2.6 mm. ⁽⁵⁾

Sensory nerve conduction studies can add much as evidence of diffuse sensory fiber involvement, localized lesions involving a cutaneous nerve or disorders that preferentially damage the sensory fibers in a mixed nerve, so they are a necessary part of any electrophysiologic evaluation of peripheral disorder⁽⁶⁾.

The treatment of finger tip amputations is controversial and so, many treatment options are available. These treatment options are either conservative management or surgical treatment. The main aim of these treatment options is to keep functional impairment to a minimum. Of course regaining sensation at the finger tip is the most important aspect of maintaining function in finger tip injury³.

 

Aim of work:

This study was conducted to compare sensory recovery using sensory nerve conductions and two point discrimination test following conservative management versus local flaps in finger tip injuries without bone exposure.

 

PATIENTS AND METHODS

 

Study design and population:

This study included Sixty four finger tip injuries in 58 patients. All patients were  recruited from the department of surgery, Kasr El-Eini hospital, Cairo University, Egypt, and department of surgery Beni-Suef University, Egypt.

Patients were allocated according to treatment policy into:

a-         Group 1: Thirty three finger tips received conservative management.

b-         Group 2: Thirty one finger tips were treated using local non-sensate flaps.

Exclusion criteria:

Smokers, patients with peripheral neuropathy (using nerve conductions) and diabetics were excluded from the study. Patients with carpal tunnel syndrome were also excluded by doing mid palm –wrist segment sensory nerve conduction and sensory nerve conductions from the other digits supplied by the median nerve. Moreover, patients with bone exposure or other associate hand injury were excluded.

On admission, adequate history taking, thorough physical examination and X-rays were taken to exclude associated hand injury.

 

Methods:

I-                    Clinical evaluation:

Two point discrimination test was conducted one year post injury for both the treated finger and the same finger in the opposite hand. The finger of the patient is touched with the two points widely separated using blunt objects then the patient must close his eyes and the pulp of the finger is touched firmly with either one point or two, starting with them far apart, and approximating them until he begins to make errors. The threshold is thus determined and the other hand can be compared. Normally a person should be able to recognize two points separated by as little as 2.6 mm on the finger pads⁵.

 

II-                 Neurophysiological evaluation:

Sensory nerve conduction studies were carried out in the clinical Neurophysiology Unit, Kasr El-Eini hospital one year post-injury using a Nihon Kohden® (Neuropack four mini) apparatus. The active and reference electrodes are 4 cm apart with the active placed 14 cm from the cathode and the stimulation is applied with ring electrodes around the digits with the cathode at the base of the digits and the ground is placed between the pickup and stimulating electrodes (orthodromic technique).

Normal values: peak latency 3.2±0.2 mseconds, amplitude 10-90uv and conduction velocity 48-64.9 m/seconds⁷.

 

III.          Surgical techniques:

A)  Conservative management (group 1):

Adequate wound debridement was done under regional ring block anesthesia, following that the wound is dressed with Vaseline impregnated gauze with fusidic acid. The finger is covered with the cut finger end of a sterile surgical glove for 48 hours. The patients are followed up in the out patient clinic and dressing is changed every 48 hours in the 1^st week and twice weekly after that until healing occur. Patients started wide range of early motion exercise from first day post injury.

B)  Local flaps (group 2):

Under local anesthesia, adequate wound debridement is done. Local flaps used are V-Y advancement flap (15 cases), cross finger flap (10 cases) and thenar flap (6 cases). Dressing change is done every 48 hours for 4 days. This is followed by motion exercises except in cases with cross finger flap where it was done after flap separation after 21 days.

The incidence of infection, joint stiffness, cold intolerance and hypersensitivity was also noted.

 

Statistical Methods

Data were expressed as mean±standard deviation (SD) or percentage (%). Comparison between the numerical data of two groups was performed using unpaired t test, Chi-square test used for comparison between qualitative data which were presented as frequencies and percentages. Pearson’s correlation coefficient was used to determine significant correlations between the different qualitative variables.  SPSS computer program (version 11) was used for data analysis. P value is considered is considered highly significant (**) if it was ≤ 0.001.

 

 

RESULTS

 

Sixty-four finger tip injuries in 58 patients were included in the study. Forty fingers were injuries due to industrial accidents and 24 injuries due to domestic accidents. 40 patients were males (68.96 %) and 18 were females (31.04%). The mean age of the patients at the initial presentations was 36.1±8.75 years (range 19-55 years) (Table 1). 33 injured finger tips were treated using conservative management (Group 1) and 31 were treated using local flaps (Group 2). Two flaps were lost in group 2 so they were excluded from the study leaving only 29 injuries for evaluation in this group.

 

1-                   Conservative treatment (Group 1) :

Thirty-three finger tip injuries were treated using this method. After adequate debridement, the mean surface area of the defect was 1.6 cm2 (range 0.5-2.2 cm2). No infection in any finger occurred during the period of treatment.

Cold intolerance was detected in 9 fingers (27.3%) after 3 months and only in 2 fingers (6.1%) after one year. Hypersensitivity was noticed in 12 fingers (36.4%) after 3 months. After one year no hypersensitivity was noticed in any finger, as shown in Table (2). No joint stiffness was observed in any finger.

 

2-                   Local flaps (Group 2):

Thirty-one fingers were treated using this method. After adequate debridement the mean surface area of the defect was 1.6 cm2 (range 0.6-2.1 cm2).  Flap separation in cross finger flap was done after 21 days. Two flaps were lost, so they were excluded from the study leaving only 29 cases for evaluation in this group.

Cold intolerance was observed in 8 fingers (27.6%) after 3 months and in 2 fingers (6.9%) after one year. Hypersensitivity was not noticed in any of the fingers after 3 or 12 months. Joint stiffness did not occur in any of the fingers. So, the difference in the development of cold intolerance and hypersensitivity between fingers treated conservatively and those treated with local flaps was not statistically significant after 12 month p>0.05, as shown in Table (2).

In the comparative and correlative results, we used only data of 58 fingers after excluding the two lost flaps and thumb, middle fingers, so we compared index’s finger data only to be statistically compared and correlated.

               

I.             Comparative results:

1.   Two-point discrimination test:

There was a highly statistically significant increase in two-point discrimination test in patients with index injury (local flaps, conservative), compared to the contra lateral healthy index (p<0.001), as illustrated in Table (3), also there was a highly statistically significant increase in that test in patients with local flaps, compared to those on conservative management (p<0.001), as illustrated in Table (4).

2.      Sensory nerve conduction studies among patients with index injury:

There was a highly statistically significant increase in peak latency in patients with local flaps, compared to those on conservative management (p<0.001), however, there was a highly statistically significant decrease in the amplitude and conduction velocity in patients with local flaps, compared to those on conservative management (p<0.001), as illustrated in Table (5).

 

II.            Correlative results:

Correlation between sensory nerve conduction parameters and two-point discrimination in the two groups:

There was a highly statistically significant positive correlation between two-point discrimination and peak latency; however there was a highly statistically significant negative correlation between two point discrimination and amplitude, conduction velocity in both groups, (p<0.001), as shown in Table (6).

 

 

Table 1. Descriptive results of patients with finger tip injuries.

 

Patients, data	Values
No. of patients	58
Age (years) Mean±SD Range	36.1±8.75 19-55
Sex Male Female	40(68.96%)* 18(31.04%)*
Number of fingers Aetiology Industrial accidents                                      Domestic accidents	64(100%)*   40(62.5%)* 24(37.5%)*

SD standard deviation

*Data are expressed as number (percentage)

 

Table 2. Complications among the two groups of patients with finger tip injuries after one year.

 

Complication	Conservative management			Local flaps			P-value
Cold intolerance	Yes	No	Total	Yes	No	Total	1.0
	2(6.1%)	31(93.9%)	33(100%)	2(6.9%)	27(93.1%)	29(100%)
Hypersensitivity	Yes	No	Total	Yes	No	Total
	0(0%)	0(0%)	33(100%)	0(0%)	0(0%)	29(100%)

Data are expressed as number (percentage)

 

Table 3. Two-point discrimination test among patients’ index and the contra lateral healthy index in finger tip injuries

 

Two point discrimination	Treated index	Contra lateral healthy index	P-value
Conservative management	2.87±0.37	2.12±0.17	0.001*
Local flaps	7.86±0.41	2.27±0.22	0.001*

Data are expressed as mean±standard deviation

*Significant at p<0.01

Table 4. Two-point discrimination test among patients with index injury.

 

Two point discrimination	Number	Mean±SD	P-value
Conservative management	29	2.87±0.37	0.001*
Local flaps	29	7.86±0.41

SD standard deviation

*significant at P≤0.01

 

Table 5. Sensory nerve conductions among patients with index injury.

 

Parameter	Groups	No.	Mean±SD	P-value
Peak latency	Conservative management	29	3.57 ± 0.33	0.001*
	Local flaps	29	4.54 ± 0.59
Amplitude	Conservative management	29	18.65 ±3.53	0.001*
	Local flaps	29	14.58 ± 2.97
Conduction velocity	Conservative management	29	48.93 ±1.94	0.001*
	Local flaps	29	40.24 ± 5.64

SD standard deviation

*significant at P≤0.01

 

Table 6. Correlation between sensory nerve conduction parameters and two-point discrimination in both groups of patients with finger tip injuries.

               

Variable	Conservative management		Local flaps
	r-value	P-value	r-value	P-value
Peak latency	0.88	0.001*	0.65	0.001*
Amplitude	-0.76	0.001*	-0.60	0.001*
Conduction velocity	-0.65	0.001*	-0.63	0.001*

*Significant at P≤0.01

 

 

DISCUSSION

 

Since the treatment of finger tip injury is still controversial, several options for the management of this type of injury are available. These options include surgical and conservative management. Surgical treatment for finger tip injury includes a plethora of options that have been developed over years. Among these options are V-Y flaps with its modifications⁸, volar advancement flaps⁹, homodigital island flap¹⁰, heterodigital island flap and full thickness skin grafting which, in absence of exposed bones, is frequently used for defect coverage due to relative ease of the procedure¹¹. Treatment of fingertip injuries must be individualized to the patient's age, sex, configuration and composition of defect, digit injured, hand dominance, pre-existing medical conditions, occupation, hobbies, and mechanism of injury. The fingertip wound should be assessed for tissue loss. If there is minimal tissue loss the wound can be debrided and closed primarily. If the fingertip wound cannot be repaired primarily and no bone is exposed, conservative treatment may be considered¹².

The main aim in management of hand injuries is reduction of functional impairment. Of course, in case of finger tip injury, this functional impairment would be sensory loss. Sensory recovery with conventional flaps leads to unsatisfactory results in a majority of patients: an average of 6-mm to 8-mm two point discrimination is reported by most authors¹³. Neurosensory flaps obtain good results regarding sensory recovery; however they require special surgical experience¹⁴.

Conservative management aims at wound healing by secondary intention which is caused by contraction and epithelization of the scar tissue and surrounding dermis that effectively reduce the subsequent size of the wound^14-16. Conservative treatment plays a significant role in the management of finger tip injuries, as was documented by Farrell¹⁴ and later by Allen¹⁷ and S.P. Chow¹⁸. Buckley et al.¹⁹ studied the conservative management of finger tip injuries. They reported excellent results with a mean two point discrimination test 4.1mm twelve months post operatively. A prospective study of seven treatment methods used on 200 fingertip injuries showed that simple dressings gave excellent results if the lengthy time to healing were taken into account²⁰. Mennen and Wise¹⁵ in a series of 200 finger tip injuries found a healing time ranging from 20 to 30 days and good functional recovery (two point discrimination test after 3 months after healing averaged 2.5 mm indicating near normal sensitivity recovery). The same conclusion was reached by Lee et al.²¹.

Although some authors believe that the size of the wound is important and place size limitations on wounds that can be treated conservatively²², several studies showed that the size, location and involved structures are not critically significant factors in the conservative management of finger tip injuries^15,21 and some other authors even go further to the use of conservative treatment in fingertip injuries with small amount of exposed bone that can be cut below the level of surrounding tissue²³.

Finger tip injuries left to heal by secondary intention do so by the process of granulation, wound contraction and epithelialization.  Granulation tissues seem actually to replace lost tissue volume while contraction pulls normally innervated skin over the defect resulting in near normal sensation and reducing the ultimate size of the scar and the newly formed epithelium is relatively normal²⁴.

The results of our study confirm the opinion of previous authors. In the group treated conservatively, there was a mean increase in two point discrimination from 2.12±0.17 mm in the contra lateral normal digit to 2.87±0.37 mm in the treated digit. However in group 2 (treated with local flaps) , there was a mean increase in two point discrimination from 2.27±0.22 mm in the contra lateral normal digit to 7.86±0.41 mm in the treated digit. This shows that conservative treatment is superior to local flaps regarding sensory recovery.

In the current study, we compared sensory nerve conduction parameters between both groups and they revealed that there was a highly statistically significant delay in peak latency and reduction of amplitude and conduction velocity in patients with local flaps compared to those under conservative management. These findings could be attributed to either local nerve injury or distal axonal damage which may be associated with more severe proximal conduction slowing as explained by Chang²⁵ but not in the same injury as we haven’t found such study in the literature, although both distal demyelination or axonal degeneration could alter proximal conduction properties and retrograde axonal atrophy is the pathologic term for a reduction in the diameter of proximal fibers.

Complications associated with conservative management are usually minor and improve with time²⁶. Drawbacks of conservative management include cold intolerance and hypersensitivity. Goitz et al.¹⁴ noticed that cold intolerance occur in 1 ⁄3 of conservatively treated patients; however this cold intolerance often decreases with time. Cold intolerance in a consequence of the injury itself ⁽²⁴⁾ and higher incidence of cold intolerance is noted with other methods of closure²⁶. Hypersensitivity can also do occur but they are usually transient. Patients with remaining hypersensitivity usually benefit from desensitization programs²⁷. Joint stiffness is also reported with conservative management; however this can be easily prevented by early range of motion exercise²⁴.

In our study, after 3 months, cold intolerance was noticed in 9 fingers in the conservatively treated group (27.3%) and in 8 fingers in the second group (27.6 %). After one year, cold intolerance was noticed in 2 fingers (6.1 %) in the conservatively treated group and in 2 fingers (6.9 %) in the second group. Hypersensitivity developed in 12 fingers in the conservatively treated group (36.4%) after 3 months. No patients complained of a hypersensitive finger after 12 months.  In the group treated with local flaps, no hypersensitivity was detected in any of the patients either after 3 or 12 months. No infection or joint stiffness occurred in either group; however two flaps were lost in the second group.

The previously mentioned data and the statistical studies show that sensory recovery in finger tip injuries treated conservatively is better than those treated with local non sensate flaps. Moreover, the difference in development of cold intolerance and hypersensitivity between fingers treated conservatively and those treated with local flaps was not statistically significant after 12 months.

 

Conclusion

Conservative treatment using repeated dressings is an effective, simple and good option for treatment of finger tip injuries without bone exposure. The sensory recovery presented by sensory nerve conductions and two point discrimination test in patients using this technique has better values than that achieved with local flaps and there is no statistical difference in the incidence of cold intolerance or hypersensitivity between the two methods of treatment. 

 

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