Proximal tibial cuff

A proximal tibial cuff which may be integrated with a cast for a lower leg fracture is stabilized on the leg by inner surfaces which conform to the injured limb and by an anterior inward projection which impresses soft tissue distal to the patella, anterior to the patellar tendon.

BACKGROUND OF THE INVENTION 
The present invention concerns a proximal tibial cuff for use in the 
treatment of fractures of the lower leg. 
As is well known, the treatment of a lower leg fracture typically involves 
the application of a plaster cast or the like to a patient's injured limb. 
In order to achieve proper healing of the fracture with a minimum of 
inconvenience to the patient, a cast should be both stable and comfortable 
and should not interfere significantly with movement of the knee. In 
addition, to further the healing process, it is also desirable that a 
lower leg cast minimize the exposure of the fracture area to 
weight-bearing forces when the patient stands on the injured leg. The 
present invention is directed toward the foregoing considerations. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention provides a proximal tibial cuff which, 
in a principal aspect, may comprise a sleeve including a lower portion of 
interior cross section substantially conforming to the leg and an upper 
portion of interior cross section substantially conforming to the knee, 
the upper portion having an anterior inward projection for impressing the 
soft tissues distal to the patella, anterior to the patellar tendon. 
In a preferred form, the cuff also includes rotation-preventing means, such 
as a pair of wings which conform to the sides of the knee; a longitudinal 
split to facilitate application to the leg; an outwardly curved upper 
posterior edge to avoid irritating contact with the skin and interference 
with movement of the knee; and means, for example defining a plurality of 
holes, to improve bonding between the cuff and a lower leg cast. 
As will be understood from the detailed description below, a proximal 
tibial cuff according to the invention may be integrated with a lower leg 
cast to provide a stable and comfortable cast structure which permits 
substantially full use of the knee and which promotes the healing process 
by transmitting weight-bearing forces around the fracture area to the 
upper leg. Further advantages of the invention will also be apparent from 
the ensuing discussion in which reference is made to the following 
drawings.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to the details of the invention as illustrated in the drawings, a 
proximal tibial cuff in the preferred form for the right leg will now be 
described. It will be appreciated that while the illustrated embodiment is 
specifically adapted for use on the right leg, a similar cuff for the left 
leg may be obtained simply by mirroring the features of the cuff shown. 
As shown in FIGS. 1-5, a proximal tibial cuff according to the invention 
may comprise a sleeve 10, including a lower portion 12 of interior 
cross-section substantially conforming to the leg (see FIG. 4) and an 
upper portion 14 of interior cross-section substantially conforming to the 
knee (see FIG. 5). The sleeve is preferably made of a material which 
provides sufficient axial rigidity to support weight-bearing forces along 
the length of the sleeve without appreciable deformation. Although, as 
will be apparent to those skilled in the art, a variety of materials are 
suitable for this purpose, a resilient plastic such as polyethylene is 
preferred so that the sleeve will be somewhat flexible transversely to its 
axis. A proximal tibial cuff with such flexibility will be both easy to 
apply (as will be discussed below) and capable of accommodating a range of 
leg sizes, thereby permitting the use of several standard cuff sizes. 
According to an important aspect of the invention, the upper portion 14 of 
the sleeve is provided with an anterior inward projection 16. The 
projection 16 is adapted to impress the soft tissue (i.e., the skin and 
subcutaneous tissue) distal to the patella, anterior to the patellar 
tendon. As will be discussed later, this action of projection 16 serves to 
stabilize the cuff when it is applied to the leg. It should be noted that 
projection 16 impresses the soft tissues only to a degree sufficient to 
stabilize the proximal tibial cuff and does not unduly constrict the knee. 
To ensure further the rotational stability of the cuff, the sleeve is 
provided with rotation-preventing wing members 18 and 20 which extend from 
the upper portion 14 thereof (see FIGS. 1 and 3). As shown, wings 18 and 
20 are preferably designed substantially to conform to the medial and 
lateral regions of the knee, respectively, and the upper edges thereof are 
flared outwardly to avoid irritating contact with the skin. Similarly, as 
shown in FIG. 2, it is preferable that the upper posterior edge 22 of the 
sleeve be curved outwardly to ensure patient comfort. The outward 
curvature of edge 22 provides a smooth surface for contacting the skin and 
permits substantially full flection of the knee without interference from 
the cuff. 
As is best seen in FIGS. 3-5, the present embodiment of the proximal tibial 
cuff also includes a longitudinal split 26 to facilitate its application 
to the leg. In the form shown, longitudinal split 26 runs through the 
posterior of the cuff, approximately at the center. When the cuff is made 
of a resilient plastic (e.g., polyethylene) as discussed above, the edges 
28 and 30 of the split may overlap as shown to accommodate variations in 
leg size, and the cuff may be applied simply by spreading edges 28 and 30 
and placing it around the leg. The cuff will then return to the proper 
shape due to the resilience of the plastic. 
The preferred position of the proximal tibial cuff when applied to the 
right leg is depicted in FIGS. 6 and 7. As shown, the projection 16 is 
located distal to the patella, anterior to the patellar tendon, with the 
lower and upper portions of the sleeve 12 and 14 conforming to the knee 
and leg and wings 18 and 20 conforming to the medial and lateral regions 
of the knee as previously described. 
With the cuff in position as shown, its conforming inner surfaces act to 
maintain it in a substantially stable position. More importantly, however, 
anterior inward projection 16, by impressing the soft tissues as described 
above, provides an additional degree of stability which effectively fixes 
the position of the cuff on the leg. 
After the cuff has been applied to the leg, a plaster cast or the like can 
be molded over the cuff as shown in FIG. 8. Generally, in the case of a 
lower leg fracture, the cast will encompass substantially the entire lower 
leg, including a portion of the foot (see FIG. 8). When the cast hardens, 
it will bond firmly to the cuff to form a rigid, integrated cast 
structure. To improve bonding between the cuff and the cast material means 
defining a plurality of holes 24 (or other bonding improvement means such 
as surface projections) may be incorporated in the cuff as shown in FIGS. 
1-3. 
It is readily apparent that the integrated cast structure just described 
will be both stable and comfortable about the proximal tibial region. In 
particular, because the cuff is stabilized in position as previously 
discussed and the hardened cast material is bonded firmly to the cuff, the 
entire cast structure will necessarily be stable about the proximal tibial 
region. Furthermore, because it is primarily the cuff which is in direct 
contact with the leg in this region, this stability is achieved without 
sacrifice of patient comfort or interference with use of the knee. 
Beyond the foregoing advantages, the integrated cast structure 
(incorporating the proximal tibial cuff as described) forms a rigid 
weight-bearing member which promotes the healing process by transmitting 
weight-bearing forces from the upper leg to the foot, bypassing the 
fracture area. 
While the foregoing discussion describes a preferred embodiment of the 
invention, it will be apparent to those skilled in the art that changes 
can be made without departing from the principles and spirit of the 
invention, the scope of which is defined in the appended claims.