Non-water-activated cast

Abstract

A non-water-activatable cast has one or more layers of sheet-like material which create a combined flexibility, stiffness, or rigidity so that the cast may be manually positioned in substantial contact with a lower extremity to be received within the cast. As such, the cast is not only readily deployable by a patient, but has predetermined flexibility located and selected to control ankle movement within a therapeutically appropriate range, whether used by itself or in association with a related orthosis, such as a CAM walker. In certain applications, the cast likewise offloads or otherwise redistributes force by virtue of the rigidity of the plantar impact surface on such cast and the rigidity of other cast portions.

What is claimed is: 
     
         1 . A cast for a lower extremity to be treated, the cast comprising:
 at least two layers of sheet-like material, wherein the layers have a predetermined, combined flexibility selected to have the layers manually transformable from a first, pre-application configuration before fitting on the lower extremity, to a second, post-application configuration after the fitting on the lower extremity;   wherein the first configuration comprises a blank of the sheet-like material extending transversely between opposite side edges by a first amount sufficient to substantially, circumferentially enclose the lower extremity after manipulation of the blank, the sheet-like material extending longitudinally between upper and lower ends by a second amount sufficient to locate the leg and the foot of the lower extremity at the upper and lower ends, respectively, after fitting on the lower extremity   wherein the second, post-application configuration is formed in response to manual force applied to the blank to bring the side edges relatively toward each other to define a volume into which the lower extremity is received and to define an inner surface to substantially contact opposing portions of the lower extremity when received therein;   wherein the predetermined flexibility is selected to permit the inner surface of the cast to maintain the substantial contact with the lower extremity during walking on the lower extremity; and   wherein the predetermined flexibility is selected to limit at least one of plantar flexion, dorsiflexion, eversion, and inversion of the ankle of the lower extremity by at least 50% compared to a corresponding, non-casted movement of said ankle.   
     
     
         2 . The cast of  claim 1 , wherein the predetermined flexibility is selected to control the ankle movement by at least 80% compared to the corresponding, non-casted movement. 
     
     
         3 . The cast of  claim 1 , wherein the predetermined flexibility is selected to limit the ankle movement to at least 90% of the corresponding, non-casted movement. 
     
     
         4 . The cast of  claim 1 ,
 wherein one of the layers comprises an inner layer, the material of the inner layer consisting essentially of water-resistant material; and   wherein the other of the layers consists essentially of bands of semi-rigid polymeric material arranged in a weave pattern to form a spica, the spica comprising a series of overlaps and at least one opening, the spica being configured to locate the opening at the heel of the extremity and at least one of the intersections at the ankle joint of the lower extremity.   
     
     
         5 . The cast of  claim 1 , wherein the cast is configured to have the inner surface of the cast directly contact the lower extremity when received therein. 
     
     
         6 . The cast of  claim 1 , wherein the cast is configured to have the inner surface of the cast indirectly contact the lower extremity when received therein. 
     
     
         7 . The cast of  claim 1 , wherein the blank comprises a cylinder having a cylinder wall and a slit defined therein by the opposite side edges of the blank, the slit extending longitudinally between the upper and lower ends of the cast, the cylinder wall being configured so that the width of the slit is manually expandable by a sufficient amount to position the cylinder wall around the lower extremity. 
     
     
         8 . The cast of  claim 1 , wherein the cast consists essentially of material that is non-water-activatable. 
     
     
         9 . The cast of  claim 8 , wherein one of the layers comprises an outer layer of semi-rigid polymeric material having a thickness ranging between 0.4 mm and 0.9 mm. 
     
     
         10 . The cast of  claim 9 , wherein one of the layers comprises cushioning material. 
     
     
         11 . The cast of  claim 9 , wherein the sheet-like material is characterized by a semi-rigidity selected to place the cast in a weight-bearing category in terms of therapeutic uses to offload a therapeutically significant percentage of force forward of the heel during heel strike, and to control ankle movement at therapeutic levels comparable to a CAM walker. 
     
     
         12 . The cast of  claim 9  wherein the sheet-like material is characterized by a semi-rigidity selected to place the cast in a weight-bearing category in terms of therapeutic uses to offload a therapeutically significant percentage of force of the forefoot, and to control foot movement at therapeutic levels comparable to a CAM walker 
     
     
         13 . The cast of  claim 9 , wherein one of the layers is located radially inwardly from the outer layer, and comprises knitted fabric configured to have at least one of the properties selected from the group consisting of anti-microbial properties, insulative properties, wicking properties, and anti-friction properties. 
     
     
         14 . The cast of  claim 9 , further comprising at least one sensor deployed at a sensor location on the inner surface of the cast, the sensor configured to receive at least one input corresponding to at least one of force, pressure, temperature, and acceleration, the input further corresponding to a portion of the lower extremity positioned at the sensor location when the lower extremity is received in the cast. 
     
     
         15 . A cast for a lower extremity to be treated, the cast consisting essentially of material that is non-water-activatable, the cast comprising:
 a blank comprising at least three layers of sheet-like material dimensioned to circumferentially enclose the lower extremity to be treated, the layers extending from an upper end to be located on the patient's leg between the knee and the ankle to a lower end to be located on the patient's foot between the ankle and the toes;   wherein the layers have a pre-determined, combined flexibility selected to have the layers manually transformable from a first, pre-application configuration before fitting on the lower extremity, to a second, post-application configuration after the fitting on the lower extremity;   wherein the first pre-application configuration of the blank is selected from the group consisting of a planar sheet having opposite side edges, a cylinder, and a spiral-wound roll;   wherein the second, post-application configuration comprises an inner surface having substantial contact with portions of the lower extremity enclosed by the sheet-like material when fitted to the lower extremity;   wherein the predetermined flexibility is selected so that, when the cast has been fixed in the second, post-application configuration, movement of the ankle in plantar flexion, dorsiflexion, eversion and inversion is limited by 90% compared to a corresponding, non-casted movement to control ankle movement within a therapeutically selected range during walking on the lower extremity;   wherein one of the layers comprises an inner layer, the material of the inner layer consisting essentially of water-resistant cushioning material;   wherein a second one of the layers consists essentially of a semi-rigid polymeric material characterized by a semi-rigidity selected to place the cast in a weight-bearing category in terms of therapeutic uses, to offload a therapeutically significant percentage of force forward of the heel during heel strike, and to control ankle movement at therapeutic levels comparable to a CAM walker; and   wherein a third one of the layers is located radially interior to the inner layer, the third one of the layer comprising knitted fabric configured to have at least one of the properties selected from the group consisting of anti-microbial properties, insulative properties, wicking properties, and anti-friction properties.   
     
     
         16 . The cast of  claim 15 , wherein the average thickness of the sheet-like material ranges between 0.3 mm and 35 mm. 
     
     
         17 . The cast of  claim 15 , wherein the second one of the layers comprises bands of the semi-rigid polymeric material arranged in a weave pattern to form a spica, the spica comprising a series of intersections and at least one opening, the spica being configured to locate the opening at the heel of the extremity and at least one of the intersections at the ankle joint of the lower extremity. 
     
     
         18 . An orthosis for a lower extremity to be treated, the orthosis comprising:
 a rigid frame having an inner surface;   a cast comprising a plantar portion and a leg portion, the portions having respective outer surfaces;   wherein the inner surface of the rigid frame engages at least one of the outer surfaces of the cast;   wherein the cast is formed of at least two layers of sheet-like material, wherein the layers have a predetermined, combined flexibility selected to have the layers manually transformable from a first, pre-application configuration before fitting on the lower extremity, to a second, post-application configuration after the fitting on the lower extremity;   wherein the first configuration comprises a blank of the sheet-like material extending transversely between opposite side edges by a first amount sufficient to substantially, circumferentially enclose the lower extremity after manipulation of the blank, the sheet-like material extending longitudinally between upper and lower ends by a second amount sufficient to locate the leg and the foot of the lower extremity at the upper and lower ends, respectively, after fitting on the lower extremity   wherein the second, post-application configuration is formed in response to manual force applied to the blank to bring the side edges relatively toward each other to define a volume into which the lower extremity is received and to define an inner surface to substantially contact opposing portions of the lower extremity when received therein;   wherein the predetermined flexibility is selected to permit the inner surface of the cast to maintain the substantial contact with the lower extremity during walking on the lower extremity; and   wherein the predetermined flexibility is selected to limit at least one of plantar flexion, dorsiflexion, eversion, and inversion of the ankle of the lower extremity by at least 50% compared to a corresponding, non-casted movement of said ankle.   
     
     
         19 . The orthosis of  claim 18 , wherein the orthosis comprises a CAM walker, and wherein the rigid frame comprises a plantar support member and a leg bracing member, the plantar support member adapted to receive thereon the plantar portion of the cast, and the leg bracing member is configured to engage the leg portion of the cast. 
     
     
         20 . The orthosis of  claim 19 , wherein the cast consists essentially of material that is non-water-activatable.