The document provides details on the Wilmer Carrying Orthosis (WCO), a shoulder orthosis developed in the 1960s. It describes the biomechanics of shoulder subluxation and limitations of other treatments. The WCO works by suspending the arm near the elbow, using gravity to push the humerus back into place. This avoids loading the neck and allows for neutralization of the subluxation. Conventional orthoses rely on forces around the arm, neck or shoulder, which can cause slipping and are not effective for permanent use. The WCO's biomechanics provide balanced forces to correctly position the humerus without taxing other areas.

1. Wilmer carrying Orthosis(WCO)
Smita Nayak
Demo(P&O)
PDUNIPPD

2. Introduction
• Orthoses are orthopaedic appliances used to
support, align, prevent or correct deformities of a
body part or to improve function of movable
parts of the body (Edelstein and Bruckner,
2002”).
• The International Standards Organisation has
defined orthoses as: an externally applied device
used to modify the structural and functional
characteristics of the neuro-muscular-skeletal
system (Bowker et al.,1993).

3. CONT..
Orthosis can be defined as a mechanical construction
intended to improve a functioning part of human body
where the anatomical structures are still present.
Orthoses fulfill their task by exertion of forces on to the
anatomical structure.
Depending on the upper limb segment involved and
depending on the functional requirements a specific
pattern of forces between the orthosis and the body is
needed. Therefore no universal upper limb prthosis is
exist. However every orthosis needs to fulfill some basic
requirements concerning cosmesis, comfort and control.

4. Cont..
• The Wilmer Carrying Orthosis is the original ‘Wilmer’,
a shoulder orthosis (also known as shoulder brace or
shoulder splint), developed at Delft University of
Technology.
• The WILMER Orthosis is developed in the early
1960s by the WILMER group of the Mens section
Machine Systems of the current faculty Design
Construction and Production of the Delft University
of Technology. The initiator and large motor behind
the prosthesis and orthosis developments of this
group was Prof Ir JC Cool.

5. Types of WCO
1. Wilmer shoulder orthosis ( Standard unit,
Hand free unit and wrist free unit)
• Wilmer adjustable shoulder orthosis (Modified design)
2. Wilmer elbow orthosis
• Wilmer elbow orthosis for children
• Wilmer elbow extension orthosis

6. Wilmer shoulder orthosis (WSO)
• The WSO is designed for the patients with Brachial
plexus injury and hemiplegia who suffer a complete
paralyzed arm. In stroke patients an incidence of
shoulder subluxations reported ranging from 17% to
81% (Linn SL, et al )
• Orthosis is intended for people suffering from
a partially dislocated or completely dislocated shoulder
(luxation). This often painful situation prevents proper
functional use of the affected arm. The arm hangs from
its capsule and ligaments and in time dislocates further
and further.

7. Limitation of other available treatment
• The effect of some basic support techniques on subluxation
shown that effectiveness of these systems is limited. In
general they are unable to control the subluxation neutralize
longer periods (Birds, et al ).
• Less conventional treatments are available for example
microsurgical reconstruction post-plexus lesions. The ever-
advancing current improvements in microsurgery technical
techniques, as well as increased possibilities of regeneration
of zenu wen have contributed a lot to it improving the
perspectives of one small group of patients with plexus
lesions. Despite this, there is still a large one group of patients
with these techniques do not offer a solution.

8. Cont..
• Also treatment with functional electro- stimulation
(FES) is used in patients with shoulder subluxation as
due to loss of control over shoulder muscles. This
technique leaves during short-term use shows a
positive effect, but late after stopping treatment quite
quickly see the same problems as not patients treated
with FES (Linn SL, et already ).
• Due to the effective use of the forces in and on the
body WCO is the only one capable Orthosis to actually
make the subluxation permanent neutralize.

9. Specifications of the WCO
• Effective neutralisation of shoulder subluxation.
• Regain some of the arm functions.
• Reduced chance on oedema formation in hand, fingers and
forearm.
• Reduced pain and discomfort in arm and shoulder.
• No neck loading.
• Only minor limitation of arm mobility.
• Can be worn fully underneath clothing.
• High wearing comfort partly because of open and lightweight
construction.
• Custom made to perfectly fit the arm
• Light weight Orthosis: less than 170 gram
• Weight of shoulder strap: 75 gram.

10. Wilmer Carrying Orthosis (WCO)

11. Function
• Treating a shoulder (sub)luxation by wearing a sling
may reduce loading on the ligaments and capsule, it
doesn’t neutralise the (sub)luxation itself. On top of
that a sling needs to be worn over clothing, highly
limits arm mobility and it loads the neck.
• The use of the WILMER Carrying Orthosis does lead to
effective neutralisation of the (sub)luxation. The
Carrying Orthosis suspends the arm close to the elbow
leading to a slight misbalance of the weight of the
forearm in reference to the weight of the upper arm.

12. Cont..
• When the forearm is directed downwards by gravity,
the upper arm is, at the same time, pushed upwards,
leading to the head of the upper arm finding its
support in the shoulder joint again.
• The Carrying Orthosis is equipped with a shoulder cap
that leaves the neck and often painful shoulder head
unloaded. The design of the Carrying Orthosis allows it
to be worn fully underneath clothing. There is only a
mild limitation of arm mobility. The predominantly
horizontal position of the forearm reduces the chance
on oedema formation.

13. The WILMER carrying orthosis standard
unit, supports the paralyzed arm, wrist and
hand

14. Standard Unit – With hand support
• The standard unit is used when full hand support
is required.
• The hand support brings the hand to a stable rest
position.
• The curved edge ensures that the hand does not
slip from the support.
• The perforated plastic (PE) hand support has
rounded edges, giving a comfortable hand
support, which is well ventilated, but also easy to
clean.

15. WILMER hands-free unit which optimally
supports the paralyzed arm and wrist ensuring
optimal hand and finger mobility

16. Hands-free unit – With handspoon
• The model with a hand spoon is used by people
whose control over the fingers of the hand is still
(partly) present, but have insufficient control over
the wrist.
• Through a small perforated hand spoon placed in
the palm of the hand, the wrist is supported, but
the fingers and thumb remain free so that
(limited) functionality is possible.
• This creates an optimal combination of control
and functionality.

17. WILMER wrist-free unit which optimally supports the
paralyzed arm ensuring optimal wrist, hand and finger
mobility

18. Wrist-free unit
• The wrist-free unit leaves both wrist and hand
free.
• Ideal for people with good control over hand
and wrist.
• This gives you maximum freedom and
functionality at your hand.
• Comfortable suspension of frame on the
forearm.
• Adjustable wrist straps.

19. Wilmer2 Carrying Orthosis(W2CO)

21. Specials
• Occasionally, a complete individual hand
orthosis is produced that is connected to the
WCO’s frame.
• This happens, for example, if there is severe
spasticity around the hand and fingers.
• The original Carrying Orthosis model is a more
convenient choice in that case than
the Wilmer2 Carrying Orthosis

22. BIOMECHANICS OF SUBLUXATION
Fig 1
Fig 2

23. CONT..
• The humeral head shares only a very small
articular surface with the scapula. The structure
of joint shows clearly that the shape stability of
this joint is limited. Muscles provide compression
of this joint causing humerus against the scapula
remains pressed.
• The down and laterally sloping edge of the
scapula articular surface ensures that, at
sufficient compression force, the gleno-humeral
joint remains stable. For this compression force is
mainly the m.supraspinatus responsible.(Fig 2)

24. CONT..
• EMG studies (Basmajian, et al.)showed that the
activity of the m.supraspinatus (along with the
morphology from the down and laterally runaway
articular surface of the scapula) contributes to
the resistance of it healthy gleno-humeral joint
against subluxation.
• The more vertical working m. biceps, m. triceps
and most of the m. deltiod thus fulfill a lot
smaller to no role in the active stabilization of the
joint against subluxation.

25. Fig 3

26. • The stability of the joint is only for a very small part in the
form of the articular surfaces. Haircut and Ties (3)(Fig 1), but
above all an active contribution of the muscles (especially m.
supraspinatus) are necessary to ensure the integrity of the
joint.
• Loss of muscle around the shoulder (and so especially failure
of the m. Supraspina- tus) as a result of, for example, a CVA or
a brachial plexus lesion leads to that there is no longer an
active compression of it the gleno-humeral joint. The
humerus no longer grows active against the articular surface
of the attracted scapula.

27. • As a result of the mass of the arm and of the to
downward and laterally divergent joint plane of the
scapula(Fig 3) the haircuts and bands of the joint more
or less more permanent tensile loads.This continuous
load leads to one viscous deformation of this
anatomical structures: they stretch.
• Due to the low dimensional stability of the joint (Fig 1)
is only a small one elongation of these structures
sufficient to vertical stability of the joint is not to
guarantee more. With others words: the humerus
subluxates.

28. Biomechanics of conventional orthosis
used for shoulder subluxation
• When using a orthosis for a shoulder subluxation
is in first attempted to subluxation to lift. From a
mechanical perspective this means that there is
one somewhere on the arm upward force is
required which the downward gravity on the arm
compensates.
There are actually only three techniques to do that.
1. The first technique is through a support point
under the armpit. This technique, like used in, for
example, the Bobathsling (Birds I, et al ), uses the
shape of the head of the humerus.

29. Cont…
• The idea is to use one roll a
force in the patient's armpit
can induce those in the neck
of the humeral head can push
it up. The humeral head
geometry, however, leaves
immediately, that this can
only be done by this also to
push out (laterally). That is an
unwanted side effect,
because bring the viscous
structures around again the
joint (capsule and bands)
further can be stretched.

30. Cont..
2. The second technique is to raise the arm pull with a cuff
around the upper arm ( Fig 4).
• The cuff is placed in such, orthotics pulled tightly around the
upper arm. By tightening the cuff a normal force of the cuff
generate on the skin and vice versa(Fig 5). Because of this
normal force, there arises also a frictional force (of skin on
cuff and vice versa). The frictional force depends on the
prevailing friction coefficient μ via:
F friction = μ.F normal
• A small coefficient of friction requires therefore high normal
forces around the required frictional forces (necessary to
mass of the arm) generate.
• The problem now is that the friction coefficient in contact
with the human skin is not constant.

31. Biomechanics of cuff
Fig 4
Fig 5 ( F Wrijving=F frictional, F bandje=
Fstrap)

32. Cont..
• The human skin is capable of being ephemeral
generate very high frictional forces, but because
of perspiration, among other things this cannot
be sustained for long. Sometimes very low
coefficient of friction of the human skin in
upward, required very strong normal forces.
• Then required forces are generally too high for
permanent contact with the skin support. The
result is therefore ultimately skin crawls under
the cuff and thereby re-creating the subluxation.

33. CONT..
3. The third technique is to generate one upward force against
the 90 ° flexed forearm.
• This technique is widely used in all kinds of models slings
and mitellas.(Fig 6)
• This techniques mechanical perspective is most promising.
We can't really do much with orthotics more than applying
well selected compressive forces. In this technique the arm
is lifted by two pressure forces on the forearm, so that
would can work.
• To be able to properly assess whether and how the sling of
fig 6, is able to neutralized shoulder subluxation
permanently a free-body sketch (VLS) of this situation are
displayed (Fig 7).

34. SLING AND MITELLA

35. Slings Biomechanics
Fig 6 Fig 7

36. CONT..
• The VLS in Fig 7 shows that there is none balance. Balance
of forces demands it seems that F mass is equal to the sum
of F b1 and F b2 . However, F mass has another (smaller)
arm in relation to the elbow than the resultant of F b1 and
F b2 . The sum of the moments relative to the elbow is
therefore not equal to zero.
• The forearm will by the ruling forces want to flex
further. Even if we do it support point of F b1 closer to the
elbow sliding (beyond F mass ) goes wrong. theory we can
for the forearm then balance of forces and balance of
moments to get. However, that will be relatively large
F b1 lead and a much smaller F b2 . If we analyze that
situation for the VLS of the sling itself (right part Figure 7),
then there again no moment balance.

37. CONT..
• In theory this could still be accomplished via a frictional force at the
support point with the neck. However, the same analysis as for the
upper arm cuff of Figure 4 also applies here. Long-term high friction
generate forces on human skin undesirable and practically not
feasible. The VLS demands from the sling itself as a result that
F b1 and F b2 are (approximately) the same size.
• The result is therefore again the situation where the resulting
moment in the bottom want to flex. In general it is the situation of
this group of patients around the elbow so that it is internal (with
muscle force) to stabilize this flexing moment is not possible.
• The arm will then also flex, the sling slips around the neck, its
support point of F b2 comes up and it support of F b1 (and with it
the elbow, upper arm and humerus) drops to down.
• The default response is then to tie the sling shorter, but that does
not change the interplay of forces: the sling continues to slide along
the neck and the subluxation persists after a relatively short time
return.

38. Cont…
• In the three above-described supporting techniques, a lot
of attention has been paid to the choice of where the up
working force must seize the humerus must be back in
place to get.
• It is for a good orthosis however at least as interesting to
consider think about where the reaction force of the
Orthosis should be in a downward direction
engage. ( Newton 's 3rd law requires that the upward force
on the arm, intended to push back the humerus, in
opposite direction through the arm on the orthosis will
work.
• The orthosis is also possible only stay in place if he is
elsewhere leans on the body. In that place it will body on
the orthosis one up need to generate targeted force and
the orthosis on the body one downgenerate targeted force.

39. Cont…
• In Figure 7 this force is represented as F neck . Now on that F neck
is the same size as F mass . In other words, the mass of the arm
hangs completely on the neck. Remember that we're talking about
an orthosis here for permanent use. The subluxation goes on no
longer automatically and the user of the orthosis will be the rest of
it have to use life. Taxing the neck with the mass of the arm is then
not a good idea either. Also the way of support as in Figure 4 is less
successful
• Hereby solution there is a vertically oriented load (F shoulder ) on
the humerus region (Fig 8). That is not such a good idea either for
this patient population.
• In summary, it can be said that the conventional solutions to deal
with a orthosis to neutralize shoulder subluxation serene little from
a mechanical perspective be effective. This explains the meager
results of these systems in practice.

40. Fig 8

41. Biomechanics of Wilmer Orthosis
Fig 9
FIG 9
FIG 10

42. Cont..
• The size of F humerus depends on the degree of imbalance
between Fmass and Fresultant . A bigger imbalance
(chosen more proximally suspension point of the shoulder
support) to a greater upward force on the elbow (F elbow )
and thus to one greater F humerus and vice versa.
• Other opted orthosis generally supports the humerus
region and neck region respectively
• The WILMER Orthosis is opted for support in the region
correctly between the two. There also occurs the
interaction of F shoulder through a soft shoulder
patch. This is one happier location chosen for is carrying
the permanent load of the arm, than the humerus region
or the neck region.

43. • The weight of the forearm forces the upper arm
upwards, thereby neutralizing a shoulder
subluxation. One suspension point on the
forearm is sufficient for the orthotic function. The
point is created by a tension band that suspends
the arm on the shoulder. A shoulder cap
transmits the suspension force to the body. A
chest strap keeps the shoulder cap in place. All
components are situated near the limb and
therefore the orthosis can be worn underneath
the clothing without problems.

45. • In Fig ‘a’ the forces acting on the subsystem of the forearm
are shown.
• In Fig ‘b’ shows the return of the forces in elbow, where the
forces acting on the subsystem of the arm also shown.
For the equilibrium a reaction force in the shoulder is needed.
• In Fig ‘c’ the subsystem of forearm and upper arm are
combined to the system of the complete arm. The force in
the elbow is now an internal force system. The resulting
gravity force of the complete arm acts distally of the
suspension force. The reaction force in the shoulder ensure
the equilibrium of forces and indicates the successful
neutralization of the subluxation.

46. Comparison of CG in Wilmer and sling

47. Cont..
• The action line of the effective suspension
force of a mitella or hemisling lies distally to
the C.G of the bent arm. Therefore no
subluxation correcting force can exist.
• In Wilmer the displacement of the action line
of the suspension force proximal to the C.G
results in an attractive orthosis structure. The
total system acts like a balanced arm.

48. 3C Philosophy
• Cosmesis: Orthosis is in unlike many alternative orthotics,
like slings completely under clothing. The carrier of this
orthosis will therefore be less noticeable, which greatly
contributes to the cosmetic of the facility.
• Comfort: Light in weight. The lower part only weighs 170
g. The shoulder bandage only 80 g. This linked to the open
structure of the orthosis (prevented perspiration problems)
makes the orthosis pleasant to wear.
• Cotrol: The subluxation of the shoulder neutralized by in a
smart way of the forces in and on the body itself to
use. This is a good example of implicit body control.

49. Wilmer adjustable shoulder orthosis
In order to facilitate donning and doffing of the
clothes an adjustable version of the orthosis
developed by pushing against a knob principle that
is located near the elbow in the suspension strap an
unlocking action is performed. The arm with the
orthosis can now be extended. Bringing the arm
back in the 90 deg flexed position engages the lock
again, enabling the orthosis function. The working
and the fitting procedure of this adjustable
shoulder orthosis same as standard version.

50. Wilmer elbow Orthosis
• This is a dynamic orthosis degined for the
patients with paralyzed elbow. A paralyzed elbow
can be brought into flexion by maintaining
shoulder abduction angle more than 90 deg.
• More abduction angle is not acceptable in both
functionally and cosmetically.
• Addition of orthosis helps to reduced the
abduction angle to get required elbow flexion. So
there always requirement of an orthosis to get
function.

52. Cont..
• The wilmer elbow orthosis is a unilaterally construction
with two hinged frame bars made from stainless steel
tubing.
• The orthotic forearm can be positioned by anteflexion
pulse.
• Orthosis fitted to the patient arm by two fitting on
either side of the elbow joint. Orthosis only loads the
skin by the normal forces not the shear forces. Fittings
are made up of perforated plastic sheet. So the
perspiration not hampered.
• The fittings are supported only in their centre so they
adopt the shape of the arm easily.

54. • A force analysis in the orthosis of elbow shows that a
one sided hinge is free from torsional moment during
normal operation.
• A locking mechanism is added to the orthosis to enable
the patient to reatain the flail arm in the flexed
position independent of the abduction/ anteflexion
angle.
• In this locked position the arm + orthosis is suitable to
lift and carry objects. Second locking position at the
near extended arm enables pushing or clamping of
objects, this is useful in donning and doffing.

55. Locking mechanism
• Patient can flex and extend the elbow over the whole range of
motion from ‘A to D’ without interference of the locking
mechanism.
• If the patient wants to switches from flexion to extension in the
small angle area indicated with C the locking mechanism will
engage and lock the arm against extension in an approximate 90
deg flexed position.
• To unlock the arm patient has to flex the arm into area D. The lock
near extended position engaged by a switch from extension to
flexion in the small angle area indicated with B. An extension into
area A unlocks the mechanism.
• This locking mechanism can restrain some activities, like driving a
car. So to prevent unwanted locking the mechanism can be
disengage by pulling knob located at the wrist region and second
pull engages the locking mechanism again.

57. • Advantages of Wilmer elbow Orthosis
1. Restores some elbow function
2. Comfortable to wear
3. Light weight
4. Invisible to wear underneath the cloth
5. Easy donning and doffing
6. Automatic locking mechanism

58. Wilmer elbow Orthosis for children
• For the child below age of 4
years
• The Orthosis consists of two
hinged bars with a spring
attached in between them. Four
fittings transfers forces between
the Orthosis and the arm vice
versa. No locking mechanism is
incorporated. Weight varies
from 35 gram to 80 gram. With
this Orthosis the child actively
flex his arm. The possibilities to
play and development is
enhanced.

59. Wilmer elbow extension Orthosis
• Indication for this
Orthosis is the muscle
spasm.
• The Orthosis consist of
two hinged bars, fixed
on the arm with four
perforated body
adaptive fittings. An
adjustable spring
mechanism extends the
Orthosis.

60. Conclusion
• The Wilmer shoulder Orthosis known as the
only Orthosis neutralizes a shoulder
subluxation.
• Elbow Orthosis enable someone with flail arm
to actively flex and extend the elbow and the
locking mechanism having several advantages.

61. References
1: Linn SL, Granat MH, Read KR; Prevention of
shoulder subluxation after stroke with electrical
stimulation; Stroke 1999, 30 , 963-968.
2: Smith RO; Okamato GA; Checklist for the
prescription of slings for the hemiplegic
patient; Am J Occup Ther 1981, 35-2 , 91-95.
3: Cool JC; Biomechanics of Orthoses for the
subluxed shoulder; Prosthet Orthot Int
1989, 13 , 90-96.

62. Thank you