Background and Purpose: Finger flexion cascade (FFC) is a natural phenomenon that is observed in the hand at complete rest. It is the
posture/alignment of fingers with some flexion at all the joints of digits, beginning with less flexion at the index finger, progressing to more
flexion towards the little finger. The FFC may vary in individuals of different occupations as occupational activities performed over a prolonged
period may have an influence on the finger flexion ROM thereby influencing the normal FFC. Understanding the variations may serve as a
valuable tool to manage rehabilitation following hand injuries, which may include improving the finger flexion joint ROM suited to the need of
the individual. The purpose of this study was to observe, measure and document the FFC in individuals belonging to different occupations and
to analyze whether a significant variation may be seen within the occupations and between the occupations.
Methods: One hundred twenty five healthy individuals with an age ranging between 20 to 60 years who met the inclusion criteria
participated in the study. Occupations included were electricians, maintenance workers and desk workers. The participants completed a
performa related to their occupation prior to the study. Goniometry was used to measure the MCP, PIP and DIP flexion ROM of the dominant
and non dominant hand. Composite finger flexion a gross method of measuring finger ROM was also measured using a geometric ruler. The
values obtained were recorded and analyzed.
Results: To find variations within an occupation paired t test was used. ANOVA was used to analyze of variations between the 3 groups.
The results between the groups were found to be statistically significant at p value < 0.05.
Conclusion: The finger flexion cascade was found to vary in individuals belonging to different occupations therefore occupation has an
influence on the normal FFC which suggests that following hand injuries rehabilitation program can be aimed at achieving hand function
depending upon the demand the occupation places over the hand.
Keywords: Cascade; Range of motion measurement; Goniometer; Hand injuries; Occupation.
Introduction
Human hand is a highly specialized instrument which serves
us well in multitude of ways. It is a primary effector organ for
our complex motor behaviors. Hand is intimately correlated with
the brain. Our hands contribute to mental processes of thought
and feelings. The functions of the hand are unique, which cannot
be substituted by any other part of the human body. We use our
fingers without an observation as to how they function. If you
keenly observe you will be able to appreciate that the fingers of
our hand at rest form an attitude which is often referred to as
the flexion cascade. According to the Moby’s medical dictionary
8th edition 2009, Cascade is defined as any process that develops
in stages, with each stage developing on the preceding one, often
producing a cumulative effect. It may also be defined as the series of physiological processes that occur in successive stages and
each of the process is dependent on the preceding one to produce
a cumulating effect (Houghton Miffliz 2002).
The Finger flexion cascade (FFC) at rest is the posture/
alignment of fingers with some flexion at all the joints of the digits,
beginning with less flexion at the index finger and progressing
to more flexion towards the little finger (Text Book Of Rosen’s
emergency medicine – Concepts & Clinical Practice – Marx Hock
Berger Walls -7th Edition). Ideally, the ‘Cascade sign’ indicates
natural flexion of the fingers in which the tips point to the
scaphoid bone at the base of palm [1,2]. The tone and flexibility
of the soft tissues in a resting hand is responsible for the cascade
sign in normal subjects. When this normal phenomenon is
disrupted due to any injury to the flexor tendons or digits it may lead to an altered finger flexion cascade which may impair the
function of the hand as a whole. Among the flexor tendons injures
the most commonly involved tendons are flexor digitorum
superficialis (FDS) and flexor digitorumprofundus (FDP) leading
to an abnormal FFC [3].
Earlier studies have highlighted the importance of observing
the flexion cascade following hand injuries as it gives us an idea
about the involvement of flexor tendons [1,3]. Though, FFC is
observed and assessed for all hand injury patients there is a lack
of literature on reference normative values to identify abnormal
flexion cascade. Various studies have been done to measure
the flexion and extension angles of resting fingers and wrist in
relation to forearm and shoulder posture in normal subjects [4].
But there are no studies that have assessed the FFC.
Occupational hand injuries are commonly seen worldwide
from industrial workers to carpenters, plumbers and various
other occupations. A study done to find the prevalence of these
injuries stated that hand and finger injuries accounted for 30% of
all occupational injuries which were more common in males with
maximum involvement of hand and finger tendons [5]. The FFC
may vary with different occupations in which the hand may be
used with various degrees of finger flexion, occupational activities
performed over a prolonged period of time may lead to a change
in the resting hand position based on the type of hand grip used,
since some occupations require more of precision handling while
some involve prehension activities and few others may involve
using both. And therefore occupation may have a significant
influence in the formation of normal FFC. The FFC at rest has
been assessed across various parameters for patients who suffer
flexor tendon injuries/ hand injuries, in terms of patient’s history,
mechanism of injury, position of hand and digits at the time of
injury, any deformities and skeletal trauma [6].
The Range of Motion (ROM) is used as an assessment tool
and an outcome measure to evaluate the joint motion and the
impact of medical, surgical and therapeutic interventions on it
by clinicians [7]. There are many different methods employed
to measure hand and finger ROM which include goniometry,
composite finger flexion to distal palmar crease, visual estimation,
torque ROM. Goniometry has been found to have a higher intrarater
reliability and can be thereby used to measure finger ROM,
while composite finger flexion has been found to have a higher
intra- rater reliability [8,9].
Following a hand injury involving the flexor tendons,
surgery and rehabilitation protocols may be designed based on
the occupation of the individual, and henceforth the decision
regarding termination of supervised rehabilitation and return
to regular activities may be based on the patient achieving the
required finger flexion cascade specific to their occupation, for
which the need of the hour is to establish baseline normative
values of the cascade sign in various occupations. Hence this
study was done with intent to observe and documents the
finger flexion cascade values in the different occupations which
could prove useful in clinical decision making in rehabilitation
following hand injuries.
Materials and Methods
Methodology
This Observational cross sectionalstudy was conducted in
three different departments of Sri Ramachandra University
which included the electrical, maintenance, and medical record
departments. Subjects, both males and females who met the
inclusion criteria were explained in detail about the nature and
the purpose of the study. An informed consent in the regional
language (Tamil) was obtained from all those subjects who were
willing to participate in the study. Subjects of both the genders
and different occupations were included in the study. Any
subjects with injury to upper limbs or congenital malformation
and deformities of hand were excluded.
The present study was conducted on 125 subjects, among
which 106 were males and 24 were females with an age ranging
between 20-60 years. Prior to the study all the subjects completed
a Performa that included questions about the hand dominance,
duration of working hours, nature of work, lifting weights, history
of hand injury, mode of transport and demographic data
Subject recruitment: Ethical committee clearance was
obtained from the ethics committee for student’s proposal, Sri
Ramachandra University (REF: csp\14\oct\37\198).
Instrumentation
a. Baseline finger goniometer
b. Ruler
Procedure
The subjects were made to sit comfortably on a chair with the
dominant hand well supported on a table of comfortable height
and the feet flat on the floor. The upper extremity to be tested
was positioned with the shoulder by the side, elbow flexed to
midrange, forearm supinated, and wrist in functional position
(15o-20º extension) and hand in a complete resting position
placed at the edge of the table. The therapist sat adjacent to the
patient in order to take the readings. The patient was clearly
instructed not to move his upper extremity or the fingers during
the course of assessment and to stay completely relaxed. First
a baseline finger goniometer was used to measure the resting
flexion ROM of the MCP joint of index finger. The goniometer was
placed on the dorsal aspect of the hand to be tested, such that
the stable arm lied parallel to the metacarpal of second digit and
the midpoint of the goniometer corresponded to the joint axis of
the second MCP joint, the movable arm of the goniometer from
a position of zero degrees was then moved till it lied parallel to
the proximal phalanx of the index finger, this reading was then
noted down as MCP 2nd digit. The flexion ROM of the PIP joint
of the same digit was then measured by placing the goniometer
such that the stable arm lied parallel to the proximal phalanx of
the second digit with the midpoint of goniometer corresponding
to the PIP joint axis, the movable arm from zero degrees was then
moved till it lied parallel to the middle phalanx of the same digit
and this reading on the goniometer was noted down as PIP 2nd
digit. The flexion resting ROM of the DIP joint of the same digit
was then measured with the goniometer placed such that the stable arm lied parallel to the middle phalanx with the midpoint
of goniometer corresponding to the DIP joint axis, the movable
arm was then moved from zero degrees till it lied parallel to the
distal phalanx and this reading on the goniometer was noted as
DIP 2nd digit [10]. Similarly the resting flexion ROM of the middle,
ring and little finger was measured and labelled 3rd, 4th, 5th (MCP,
PIP and DIP) respectively. The whole procedure was carried out
three times for the same hand during which a short interval of
five minutes was given between each trial. The flexion ROM of all
the digits was then measured for the other hand.
Composite finger flexion to distal palmar crease was also
measured for each hand using a geometric ruler. The position
of the subject and the therapist remained the same as for
goniometry. To measure the CFF a geometric ruler was placed
perpendicular to the palm at the level of the distal palmar crease
such that the end of the ruler marked 0cm corresponded to the
palmar crease and the marking on the ruler that corresponded
to the tip of the index finger was noted down as 2nd digit. The
therapist then measured the 3rd, 4th> and 5th digits in a similar
way. Three trials were done for each of the measurement with an interval of five minutes between each trial.
Parametric tests were used to analyze the data obtained
with R version 3.0.2. Within group analysis for goniometric
measurements of all the four digits and CFF measurement
was done using a paired t-test. Between groups analysis for
goniometric measurements of all four digits and CFF measurement
was done using ANOVA. To find out the corresponding joint
correlation across the fingers, correlation coefficient was used.
Level of significance (p value) for all the tests was fixed at p < 0.
Results
Table 1 show the demographic data and hand dominance of
the subjects. It shows that all the participants of the study were
right dominant. It also shows mean and standard deviation for
age which is significant at p value <0.05.A statistical significance
was found in MCP,PIP, DIP flexion ROM between the groups.
In electrical department the resting flexion ROM of all the 4
digits in the dominant (right) and non-dominant (left) hand was
found to be greatest in PIP joints followed by MCP and then DIP joints. MCP joint ROM was found to be greater in the dominant
hand compared to the non dominant hand. In contrast the PIP
and DIP joint ROM in the non dominant hand was found to be
greater than the dominant hand. The ROM of PIP joint within the
digits was not statistically significant. While a comparison of CFF
was found to be statistically significant (Table 2).
In maintenance department the resting flexion ROM of all
the 4 digits in the dominant (right) and non-dominant (left)
hand was found to be greatest in PIP joints followed by MCP and
then DIP joints.MCP joint ROM was found to be greater in the
dominant hand compared to the non dominant hand while no
significant difference was found in the PIP and DIP flexion ROM
between both hands while a comparison of CFF was found to be
statistically significant (Table 3).
In medical record department the resting flexion ROM of all
the 4 digits in the dominant (right) and non-dominant (left) hand
was found to be greatest in PIP joints followed by MCP and then
DIP joints. MCP and PIP joint ROM was found to be greater in
the dominant hand compared to the non dominant hand. While no significant difference was found in DIP joint ROM. The CFF
measurements were found to be statistically significant (Table 4).
Group analysis between the department shows that the
resting ROM of MCP joint was found to be greatest in subjects
of electrical department followed by MRD and then MD both in
dominant and non dominant hand. The PIP joint ROM between
the groups and both in dominant and non dominant hand was
found to be greatest in MRD compared to MD with ED being the
least. The DIP joint ROM of both dominant and non dominant hand
was found to be greatest in MRD followed by ED and then MD.
The resting ROM between the three groups showed significant p
values. The CFF was found to be statistically significant between
the groups for the dominant and the non dominant hand (Table
5a & 5b).
Table 6 shows that a significant correlation was found in MCP
flexion ROM across 2nd, 3rd and 4th digits between the dominant
and non dominant hand, except the MCP flexion ROM of 5th digit.
Table 7 shows that a significant correlation was found in PIP
flexion ROM across 2nd, 3rd, 4th and 5th> digit between the dominant
and non dominant hand.
Table 8 shows that a significant correlation was found in DIP
flexion ROM across 2nd, 3rd, 4th and 5th digit between the dominant and non dominant hand.
A significant correlation was observed for CFF across 2nd, 3rd,
4th and 5th digit between the dominant and non dominant hand
(Table 9). A correlation was found across all the four digits, in
which 2nd digit correlated with the 3rd, 3rd with 4th and 4th with 5th
digits. There was no correlation between the 2nd and 5th digits or
3rd and 5th digits (Figures 1 & 2).
Discussion
This study presents to analyze the influence of different
occupations on the finger flexion cascade, as the fingers of the
hand need to adapt to various degrees of movement suited to the
requirements of different occupations. The fingers of the hand
need to precisely and intricately move to carry out a variety of
tasks which sets the human hand apart from any other mammal.
Injuries of the hand may prove to be very debilitating as it
leads to a loss of these precise and intricate movements which
is very essential to carry out day to day activities and most
importantly when most people are dependent on it to earn a living.
And therefore determining the need to which degree the fingers
are required to move and work to the demands of an individual’s
occupation can serve as a valuable tool to manage rehabilitation
following hand injuries, which may include improving the finger flexion joint ROM suited to the need of the individual and early
return to work rather than an intensive rehabilitation program
that may take a long time to achieve nearly full functions of the
hand pre injury. This study may prove useful for framing goals
after hand rehabilitation and to monitor prognosis based on the
occupation.
Based on this study a significant difference was observed in
the finger flexion cascade among three different occupations,
the differences noticed in the resting ROM of different joints in
the hand can be attributed to the anatomical variations in the
alignment of hand from one individual to another, the tension of
the soft tissues in the hand, and the day to day activities. The ECRL
transfer for finger flexor restoration is more simple alternative
method and is done to achieve normal cascade of the fingers
[11]. The two flexor tendons responsible for flexing the finger
are Flexor digitorum Superficialis (FDS) and Flexor digitorum
Profundus (FDP). FDS acts at PIP joint and FDP at DIP joint. These tendons function in coordinated fashion and independently [12].
The only relation to flexor tendons and the flexor sheath is through
the vinculae. Vinculae are located on phalanx, dorsal surface of
and in between two tendons [13 ]. Mallon et al. [14] conducted
a study to find out the gender differences in the measuring the
finger joint ROM. The results showed that no significant effect of
gender on amount of flexion in any joints of the fingers [14].
A study conducted on seven specialized testers to assess the
reliability of three different goniometers measuring the MCP, PIP,
DIP joints of hand, placing the goniometer on lateral and dorsal
to the joint showed that there is no significant difference between
the three different types of goniometer [15].
The results of the study show that for all the participants
of the study shows that the resting flexion ROM of both the
dominant and non dominant hand was found to be greatest in
the PIP joint followed by MCP joint with the least in DIP joint.
This observation can be attributed to the natural resting position
of the hand in general wherein the MCP joint remains in the
functional position while the PIP and DIP show more flexion due
to passive insufficiency. What is worth noting is the differences
that were found between the flexion ROM of the joints based on
hand dominance and how it varied with different occupations.
It was coincidental that all the participants of the study were
observed to have right hand dominance. A study conducted on
the variation of ROM in Bengali healthy adult subjects to find out
the influence of age and gender on ROM and gradation of ROM
among healthy adults using digital goniometer for measuring
ROM in most of the body joint angles. The results showed that
there was no difference in ROM between right and left sides of
body, in both genders and among different age groups [16].
For within group analysis of each department on comparison
between the dominant and non dominant hand it was seen that in
ED the subjects were found to have greatest MCP flexion ROM on
the dominant side, as their occupation requires using instruments
like screw drivers, spanners and wiring activities which involves
strong prehension grip activities. Because of greater prehension
grip activities, the ROM of PIP joints is higher than other joints in
both right and left hands. Within the group there is less significant
between values of all the three joints. Even though there is a less
significance in the analysis within the group, between the groups
it shows considerable significance.
In subjects who belonged to the MD, again the MCP flexion
ROM was found to be greater on the dominant hand while PIP
flexion ROM was found to be greater when compared to the
ED as the nature of this occupation involves handling larger
sized objects like hammers and drilling machines in which
biomechanically the PIP joints tend to go for a greater flexion
range and force generation from the flexor tendons.
Subjects from the MRD exhibited a greater flexion ROM of
PIP and DIP when compared to ED and MD as their job most
significantly involves typing and other activities include writing
and arranging files during which biomechanically the PIP and DIP
joints go in for repeated flexion movements while the MCP and
wrist remains almost in the same position. The resting flexion
ROM of 4th and 5th digits is greater compared to 2nd and 3rd digits because clinically the 2nd and 3rd digits are less mobile compared
to 4th and 5th digit.
In the analysis of medical records department, the resting
ROM of PIP joint is greater followed by MCP and then DIP joints.
On comparison of the resting ROM of MCP and PIP joints in right
is greater than left hand. This could be possibly because the right
is the dominant hand and is used more frequently for functional
activities.
In between group analysis the resting ROM of MCP joint is
higher in ED followed by MRD and then MD both in right and
left hand, because of their different activities involved in their
occupations. In PIP joint the resting ROM is greater in MRD
followed by MD and then ED. The difference in resting ROM of PIP
joint of right and left hand in between the three groups shows that
the electrical and maintenance departments were very similar
but in MRD the difference is little higher (almost 2 degrees). The
resting ROM in DIP joint in the right hand shows higher value
in MRD group followed by electrical and then maintenance
department and in the left hand it shows similar value in both
electrical department and medical record department followed
by maintenance department. This shows that there is a major
difference in finger flexion cascade among the three occupations.
The Composite finger flexion when analyzed was found to be
greatest in ED followed by MD and least in the MRD with proved
to have a statistical significance which suggests that CFF can also
be used as an alternative tool for the measurement of FFC.
All the subjects involved in the study worked for 8 hours per
day. Extraneous variables were also considered while including
the subjects in this study. All of them stayed within 5 kilometers
of the hospital and few were hostel inmates and staff quarters
residents. So the question of the hand being influenced by the
hand grip commonly used during travel was ruled out. In this
study, the statistical analysis shows that the finger flexion
cascade is near similar within the same occupation and that there is a difference in the finger flexion cascade between the different
occupations. Though the normative values are not suggested, this
calls for the attention of the concerned specialists to draw their
attention towards the finger flexion cascade and its relation to
the various occupations.
Limitations
The limitations of this study shows that there are less female subjects and hence the gender differences was not been addressed. This study has not considered the Diurnal variations.
Conclusion
The occupation of an individual has been found to have an
influence on the finger flexion cascade of the hand which suggests
that the FFC will differ from one individual to another. An
occupation based analysis proved to be helpful as it emphasizes
on the different activities that can alter this phenomenon. It is
also observed that there is a similarity in the FFC in the subjects
within the individuals. Thereby there is a need to analyze the FFC
based on occupation so as to categorize patients following hand
injuries for rehabilitation suited best to the functional needs of
their hand. Those groups of people working in electrical jobs
and maintenance showed a more closed pattern when compared
to those working with the medical records. This is valuable
information in the rehabilitation perspective. While rehabilitating
the injured hand, excessive stretching of the digits beyond the
required ranges can also compromise on the grip strengths of the
individuals thereby affecting the performance at occupation.
This study was done with a smaller sample size and suggested
that a significant variation exists and henceforth it provides
future scope for studies with a larger sample size including many
different occupations with diurnal considerations. There has
been no study till date that was done to analyze the FFC although
it has a clinical significance in the diagnosis of flexor tendon
injuries. The current study adds to the literature by focusing on
the significance of FFC measurement following hand injuries
for diagnosis as well as prognosis of these patients and their
rehabilitation.
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Figure 1: Forest Plot- Comparing the resting ROM of the MCP, PIP and DIP joints of the 2nd, 3rd, 4th and 5th digits among three different departments (Goniometer & CFF measurements on right side).
Figure 2: Forest Plot- Comparing the resting ROM of the MCP, PIP and DIP joints of the 2nd, 3rd, 4th and 5th digits among three different departments (Goniometer & CFF measurements on left side).
Table 1: Demographic data.
Table 2: Group analysis within the Electrical department.
Table 3: Group analysis within the Maintenance department
Table 4: Group analysis within the Medical record department.
Table 5a: Group analysis between the departments (Right).
Table 5b: Group analysis between the departments (Left). *Significant at p<0.05
Table 6: Correlation coefficient between resting ROM of MCP joints across fingers in right and left hands.
Table 7:Correlation coefficient between resting ROM of PIP joints across fingers in right and left hands.
Table 8: correlation coefficient between resting ROM of DIP joints across fingers in right and left hands.
Table 9: Correlation coefficient between composite finger flexion measurement across fingers in right and left hands.