Adjustable limb support

An apparatus is provided for adjustably orienting the forearm and upper arm of a human patient in a variety of angular relationships to therapeutically treat the contracted muscles in the patient's arm. The apparatus includes an exoskeletal frame having a rearward frame member and a forward frame member. The apparatus includes first, second, and third receptacle means pivotally mounted on the frame for positioning the arm in a selected therapeutic position, and orientation means for adjusting the angular displacement between the forward and rearward frame members to progressively and incrementally transport the arm among a variety of therapeutic positions. The first receptacle means includes a pair of cradles which cooperate to embrace the underside of the patient's elbow. The second receptacle means includes a forward saddle for embracing the topside of the patient's forearm. The third receptacle means includes a rearward saddle for embracing the topside of the patient's upper arm. The receptacle means cooperate through the exoskeletal frame to position the articulated human arm in a selected therapeutic arrrangement.

The present invention relates to a musculoskeletal apparatus for 
therapeutically treating contracted muscles in an injured human arm. More 
particularly, the present invention relates to an apparatus for receiving 
and adjustably orienting an articulated human limb to cause a static load 
to be applied to certain of the muscles in the human limb to 
therapeutically exercise or otherwise treat the limb. 
Muscle contracture of a human limb such as an arm is a serious problem. 
Various muscles in the human arm can become contracted due to trauma 
suffered during a serious accident such as automobile accident. For 
example, a serious head or spinal-cord injury can block motor impulse 
signals from the brain to cause the muscles in the arm to contract. 
Complications, such as myositis ossificians, after an injury can partially 
cause muscle contracture. The foregoing maladies often cause a patient's 
biceps to contract thereby drawing the forearm of the injured patient 
toward the patient's chest in proximity to the collarbone. 
Physiotherapy is often prescribed to exercise the contracted muscles in the 
injured arm. One aspect of this treatment includes the manual manipulation 
of the injured arm by a trained physiotherapist. Another aspect of this 
treatment requires the patient's injured arm to be placed in a variety of 
differently shaped casts over a long period of time in an effort to 
progressively unfold the patient's injured arm from the above-described 
contracted position to its normal fully-extended position. 
A typical rehabilitation schedule includes a periodic, often weekly, 
session with a physiotherapist. At the conclusion of such a session, a 
conventional plaster cast is usually applied to the arm to incrementally 
move the inwardly drawn forearm to a more fully-extended position. 
Initially, when the injured forearm is drawn inwardly toward the patient's 
chest, the injured forearm and the injured upper arm cooperate to define 
an acute angle. The object of the series of casts is to progressively and 
regularly increase the angular displacement between the debilitated upper 
arm and forearm until the entire arm is extendable by the patient to a 
fully extended position. 
The theory behind serial casting is that the tendons and muscles will be 
stretched while being held for a week in a fixed position. Then, apply a 
new cast with the arm now extended to a greater angle so that with each 
casting, the angle of the arm is slowly extended until it is stretched. 
This method, however, does nothing to strengthen the triceps. So, upon 
completion of the serial casting. the muscles and tendons have been 
stretched so that a full range of motion is possible. The theory of the 
present invention is to use this device to extend the arm gradually as the 
muscles are stretched and to allow some therapy (to incite action with the 
triceps) at regular short intervals. This device is to be used during 
times of relaxation to hold the arm in the furthest extension possible 
without pain but to permit therapy at any time. At each step of serial 
casting, the old plaster cast is removed and a fresh, new plaster cast is 
applied. This static load causes the muscles in the arm to be stretched 
during the period of time between physical therapy sessions. 
Conventional plaster casts do not perform or wear well when used during 
this type of treatment for a variety of reasons. It will be understood 
that a patient's inner forearm is generally bruised and made tender due to 
abrasive contact with the inner wall of the conventional plaster cast. The 
tightened, paralyzed muscles in the patient's arm cause the arm to behave 
like a "leaf" spring. Thus, the muscles exert a force to urge the inner 
surface of the patient's forearm into painful engagement with the inner 
wall of the plaster cast. Any failure of the conventional cast exacerbates 
the patient's arm injury. A conventional plaster cast does not adequately 
support the inwardly drawn, injured limb along the entire length of the 
stationary cast. It will also be appreciated that plaster casts are, as a 
general rule, uncomfortable and obtrusive. Daily showering and maintenance 
of personal hygiene is very difficult for one sentenced to wear a great 
number and variety of casts for a long period of time. Notwithstanding the 
comfort problem, it is also costly, time consuming, and otherwise 
inconvenient to have a new plaster cast applied every week or so. This is 
especially true for a patient who sustained many other serious injuries 
during the same accident in which the patient received the arm injury. 
A removable and reusable limb support designed to receive and adjustably 
orient the forearm and upper arm of a patient in a variety of angular 
relationships to therapeutically treat the contracted muscles in the arm 
would avoid the shortcomings of conventional plaster casts. 
According to the present invention, an apparatus for adjustably orienting 
the forearm and upper arm of a traumatized human arm comprises an 
exoskeletal frame including a rearward frame member and a forward frame 
member, first, second, and third receptacle means pivotally mounted on the 
frame for positioning the arm in a selected therapeutic position, and 
orientation means for adjusting the angular displacement between the 
forward and rearward frame members to progressively and incrementally 
transport the arm among a variety of therapeutic positions. 
The first receptacle means includes a pair of cradles which cooperate to 
embrace the underside of the patient's elbow. The second receptacle means 
includes a forward saddle for embracing the topside of the patient's 
forearm. The third receptacle means includes a rearward saddle for 
embracing the topside of the patient's upper arm. The receptacle means 
cooperate through the exoskeletal frame to position the articulated human 
arm in a selected therapeutic arrangement. 
One feature of the present invention is the provision of a lightweight, 
exoskeletal frame for orienting an articulated human limb such as an arm. 
The frame is easily fitted on a patient's injured arm in only a few 
moments with a minimum of effort. Further, the apparatus is easily removed 
at various times during the day. Removal of the apparatus enables the 
injured patient to shower without taking the extreme precautions that must 
generally taken to protect a conventional plaster cast. A family member or 
companion of the injured patient can be quickly trained to install and 
remove the novel frame assembly thus avoiding the great cost and 
inconvenience of traveling to an orthopedic technician skilled in the 
practice of making plaster casts. 
Another feature of the present invention is the provision of three 
spaced-apart receptacle means on the frame for positioning the articulated 
limb in a therapeutic position. The receptacle means cooperate to support 
the limb at at least three points along its length. Thus, the force 
exerted by the triceps and other muscles in the inwardly drawn injured arm 
is distributed over the entire length of the patient's arm rather than 
being applied to a small area on the patient's forearm as is the case in a 
plaster cast. Thus, the novel receptacle means advantageously minimizes 
further bruising and damage to an already injured arm. 
Yet another feature is the provision of a first receptacle means including 
forward and rearward cradles for carrying and supporting the articulated 
limb, the cradles being pivotally mounted on a plate which is pivotally 
mounted on a frame member. This feature advantageously allows the patient 
or another to pivotally adjust the position of the forward and rearward 
cradle about the patient's elbow independent of the relative position of 
the forward and rearward frame members. Thus, it is still possible to 
adjust the cradles to provide maximum elbow support and comfort after the 
patient's upper arm and forearm are restrained by the exoskeletal frame in 
the relative angular position that is appropriate to that particular stage 
of the patient's progressive rehabilitation. 
Still another feature of the present invention is the provision of 
orientation means for adjusting the angular displacement between the 
limb-carrying forward and rearward frame members. Such a feature 
advantageously enables the patient or another to therapeutically treat 
certain muscles in one or both of the forearm and upper arm by causing the 
forearm to rotate or unfold in relation to the upper arm from an 
inwardly-drawn position to a more fully extended position. The angular 
displacement between the forearm and the upper arm can be incrementally 
varied, thus avoiding the present need to apply and remove a great number 
of conventional plaster casts. The present apparatus is easily adjustable 
to provide an exact angular relationship. An angular scale can be 
inscribed on the frame to enable a user to repeatedly obtain an accurate 
measure of the angular displacement between the forward and rearward frame 
members. Thus, the required angular relationship between forward and 
rearward frame members can always be easily obtained even if the frame is 
removed and reinstalled on several occasions during the patient3 s daily 
routine.

An adjustable limb support apparatus 10 of the present invention is shown 
in an operative position on a patient's right arm in FIG. 1. The apparatus 
10 includes a rearward frame member 12 and a forward frame member 14 
pivotally mounted on the rearward frame member 12 to form an articulated 
linkage. The frame members 12, 14 having sufficient strength and low 
weight can be constructed of aluminum having a thickness of 
three-sixteenths of an inch. 
A forward saddle 16 is pivotally mounted on the distal end 18 of the 
forward frame member 14 to receive and embrace the patient's forearm (F). 
A rearward saddle 20 is pivotally mounted on the distal end 22 of the 
rearward frame member 12 to engage the patient's upper arm (U). An 
elongated plate 24 is pivotally mounted on the rearward frame member 12 so 
that the plate 24 and the forward frame member 14 are coaxially aligned to 
pivot about the same axis defined by pivot pin 25. A pair of cradles 26a 
and 26b are pivotally mounted at opposite ends of plate 24 to provide a 
means for embracing the articulated limb in close proximity to the elbow 
joint (E) uniting the forearm (F) and upper arm (U). 
Each of the saddles 16, 20 and the cradles 26a, 26b are elongated shells 
that are substantially C-shaped in transverse cross section to provide a 
cylindrically, concave surface 28 for receiving a portion of the patient's 
arm therein. Thus, the saddles and cradles are shaped and positioned to 
distribute the force exerted by the inwardly-drawn forearm (F) along 
substantially the entire length of the patient's arm. Soft pads 30 are 
mounted on the arcuate inner surface 31 of each of the saddles and cradles 
to provide comfort to the patient. Soft pads 30 may be a composite 
assembly including a cushion layer 32 of synthetic lambskin or the like 
having a backing 34 of dense long pile carpet or the like as shown best in 
FIG. 2. In addition, VELCRO strips 36 or the like can be attached to the 
pad backing 34 and also to the arcuate inner surface 31 of each of the 
saddles and cradles to enable a user to easily remove the soft pads 30 for 
cleaning. Saddles and cradles of sufficient strength and low weight can be 
constructed of aluminum having a thickness of one-eighth inch. Desirably, 
the forwardmost cradle 26a is provided with a "non-skid" friction grip 38 
fastened to its outer surface. The friction grip 38 may be constructed of 
rubber or any suitable synthetic material. The friction grip 38 is located 
to contact the arm of a wheelchair (not shown) in which the patient may be 
seated to help prevent slippage of the arm-carrying frame assembly 10 on 
the wheelchair arm. 
The apparatus further includes orientation means 40 for adjusting the 
angular displacement between the forward and rearward frame members 14, 
12. The orientation means includes a semicircular drive rack 42 mounted on 
the proximal end 44 of the rearward frame member 12, and a pinion assembly 
46 mounted on the proximal end 48 of the forward frame member 14. The 
pinion assembly 46 includes a shaft 50 extending through an aperture 52 
formed in proximal end 48 and rotatable therein, a pinion 54 rigidly fixed 
to one end of the shaft 50 to engage the drive rack 42, and a turn knob 55 
rigidly fixed to the other end of shaft 50 to enable a user to operate the 
rack and pinion assembly 40 to adjust the angular displacement of the 
frame members 12, 14. 
The orientation means 40 further includes a ratchet assembly 56 or any 
other suitable means for selectively locking the pinion assembly 46 
against counterclockwise rotation. The ratchet assembly 56 includes a 
trigger 57 pivotally mounted on the forward frame member 14 in close 
proximity to the pinion 54 and a conventional spring-loaded pawl 58 
mounted therebetween. The trigger 57 is movable between an operating 
position (shown in FIG. 1) and a locked position (not shown) to permit the 
apparatus 10 to be operated. 
The forward and rearward saddles 16, 20 can be detachably mounted to the 
frame members, 14 and 12 respectively, using the spring-loaded bushing 
assembly 60 illustrated in FIG. 4 or any other suitable attachment means. 
Bushing assembly 60 includes a bushing 62 having a resilient annular base 
64 and a retaining member 66. The base includes peripheral flanges 67. The 
base 64 and retaining member 66 each have confronting caming surfaces 68. 
The retaining member 66 is loaded in its bushing retaining position by 
spring 70 as shown in FIG. 4. For example, the bushing assembly 60 is 
operable to detach the saddle 16 by depression of the button head 72 of 
retaining member 66 in direction 74 to cause the peripheral flanges 67 to 
be radially inwardly cammed by relative movement of confronting camming 
surface 68 and disengaged from the forward frame member 14. 
The adjustable limb support of the present invention is operable in the 
following manner to therapeutically treat an injured arm. The apparatus 10 
is operable to move or unfold the patient's forearm (F) from an 
inwardly-drawn position to a more fully-extended position in opposition to 
the constant inward force exerted by the biceps in the patient's upper arm 
(U). The biceps will continue to exert such an inward force until the 
patient's arm injury has been remedied. The trigger 57 is moved to its 
operating position shown in FIG. 1 to "unlock" the forward frame member 
14. The forward frame member 14 is free to move in a counterclockwise 
direction toward the rearward frame member 12 in response to the inward 
force exerted by the patient's arm. Operation of trigger 57 enables the 
user to use turnknob 55 to incrementally rotate the forward frame member 
14 in a clockwise direction in opposition to the inward force exerted by 
the patient's triceps. It will be appreciated that the interplay and 
constant tension between the patient's inwardly drawn arm and the "locked" 
frame assembly 10 cooperate to retain the apparatus 10 on the patient's 
arm. The turn knob 55 should be rotated in a clockwise direction to cause 
the pinion 57 to navigate the drive rack 42 and to cause the patient's 
forearm (F) to be pivotally moved with respect to the patient's upper arm 
(U) about the elbow joint (E) and thus increase the angular displacement 
between the frame members 12 and 14. The graduated scale 59 can be used to 
assist the user in measuring the angular displacement between the patients 
forearm (F) and upper arm (U). 
Each of the articulated limb portions is laterally and longitudinally 
movable to a small degree within the constraints of the exoskeletal frame 
10 due to the structure of saddles 16, 20 and cradles 26a,b even when the 
articulated limb is positioned in the selected therapeutic position. Such 
slight movement is possible since the apparatus 10 is held in place on the 
patient's arm by the inwardly directed forces exerted by the arm muscles 
on the saddles and cradles and not by any affirmative gripping action or 
the like. 
The apparatus 10 is operable to return the forearm to an inwardly-drawn 
position by moving the trigger 57 to a ratchet-disabling position (not 
shown) to permit the forward frame member 14 to be freely rotatable along 
drive rack 42 in either direction. It will be understood that turn-knob 55 
will automatically rotate in the chosen direction simultaneous with 
movement of the forward frame member 14. 
In one embodiment of the present invention, the semicircular drive rack 42 
is replaced with a substantially circular drive rack (not shown). Such a 
feature permits the forward frame member 19 to be fully mobile about pivot 
25 with respect to the rearward frame member 12 so that the limb support 
of the present invention could be used on either a left arm or a right 
arm. 
Although the invention has been described in detail with reference to 
certain preferred embodiments and specific examples, variations and 
modifications exist within the scope and spirit of the invention as 
described and defined in the following claims.