Abstract:
Instruments are provided, representative embodiments of which have a first and a second jaw, from each of which at least one engaging element, whose distal end is suitable for engaging the skin tissue to be stretched, protrudes; an elastic member connecting the jaws, stressing them against each other when subjected to a traction force; and elements for adjusting the distance separating the jaws in the absence of traction force on the elastic member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Phase Application of PCT International Application No. PCT/IB2012/052189, International Filing Date, May 2, 2012, claiming priority to Italian Patent Application No. TO2011A000389, filed May 3, 2011, each of which is hereby incorporated by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to an instrument for stretching/expanding skin tissue at the margins of ulcers and wounds in general, in particular for treating skin lesions, the margins of which, which can not be directly brought close, require second intention healing (growth of fresh tissue) with conversion into wounds which are suitable for first intention healing (stitching). 
     BACKGROUND OF THE INVENTION 
     Chronic skin lesions are an illness which is becoming more and more common, above all in first world countries, with percentages ranging from 0.4 to 1% of the population. The process for healing a chronic skin lesion (ulcer) is carried out in two ways: re-epithelialization and/or the growth of granulation tissue. The reparative process is also helped by a degree of contraction determined by the activity of the myofibroblasts. Another fact established from medical science is that a soft tissue subjected to traction or to load tends to extend (skin expanders, pendants for plastic surgery, etc.). 
     To guarantee an almost constant tension, known instruments of the type indicated above use rigid frames, which, by forcing the patient into a forced position, limit the quality of life to all intents and purposes. 
     US-2003/0163160, for example, describes a representative prior art device. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an instrument which is improved with respect to those in the prior art. 
     This object is achieved by instruments having the features described and claimed herein. 
     Owing to the means for adjusting the distance between the jaws in a non-stressed position, it is possible to adapt the instrument according to the invention to wounds of varying size, in particular wounds with an opening to be closed of between 5 and 30 cm or even greater. As a result, the instrument can be realized in one size, thus significantly reducing the inventory and logistical burden. The aforementioned adjustment of the distance between the jaws takes place, in a simple, quick and effective manner, by winding an end of the elastic member around the pivot and making it come out of the front fissure of the second jaw by a desired length. 
     At the same time, while ensuring this adjustment capacity, the instrument according to the invention has a simple and essential structure which makes it reliable, economical and versatile. In particular, the elastic member keeps the two jaws together, thereby preventing undesirable separation, even when the instrument is in a position of rest, and facilitating installation. 
     The instrument according to the invention makes it possible to reduce contraction times for wounds, bringing the margins of a lesion expanded down to deep levels close together to permit direct stitching. In particular, this is indicated for grade III-IV pressure ulcers, in accordance with the NPUAP-EPUAP scale, chronic wounds affecting subcutaneous adipose tissues and/or the fascia and/or the muscle of any etiology; grade III-IV lesions in accordance with the Wagner scale with a loss of substance of soft tissues in diabetic foot; dehiscence of surgical stitching of varying depth and extension; lacerated and contused wounds with margins which cannot be brought close together for direct stitching. 
     In association with medication products which are currently commercially available, the instrument according to the invention can be used broadly in all types of chronic or acute wounds which require long repair times or need plastic surgery; in this respect, unlike in the use of plastic edges, there is no loss of muscular-fascial structures for replenishing losses of substance, thus making it possible to preserve noble and moreover sound structures. 
     In addition, the instrument according to the invention has reduced dimensions, so as to reduce the discomfort caused to the patient and to allow the patient to also lie on the side of application and to move with a greater degree of freedom. This provides an improvement in the quality of life of the patient, avoiding the instigation of new lesions due to the fact that he/she cannot be mobilized. 
     Further advantages and features of the present invention will become evident from the detailed description which follows, given by way of non-limiting example and with reference to the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of an instrument according to the invention, 
         FIG. 2  is a perspective view of two jaws of the instrument shown in  FIG. 1 , 
         FIG. 3  is a plan view of the instrument according to the invention, 
         FIG. 4  is a lateral elevated view, partially in section, of the instrument according to the invention, 
         FIG. 5  is a view from the front of the instrument according to the invention, and 
         FIG. 6  is a view, on an enlarged scale, of a pivot which forms part of the instrument according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     An instrument for stretching skin tissue at the margins of ulcers, wounds and the like comprises a first and a second jaw  10 ,  12  connected by an elastic member, such as a strip  14  of elastomeric material, in particular silicone. The jaws  10 ,  12 , which are connected by the strip  14 , therefore face each other and are spaced apart from each other (see  FIG. 1 ). The strip  14  has indicator marks  16  of the stress state, the function of which will be explained in detail hereinbelow. 
     Each jaw  10 ,  12  has a substantially flat body which is made of plastic material and is formed by two superimposed half members  18   a ,  18   b  which are joined by techniques which are conventional per se, for example by means of welding. The bodies of the jaws  10 ,  12  can be made of any plastic, or possibly even metallic, material which is not resorbable and is suitable for use in the medical field. 
     The major faces of the body of each jaw  10 ,  12  have a respective notch  20  to promote grip, and in addition two engaging elements, typically made of metal, protrude from the bottom major face, the distal ends of which engaging elements are designed for engaging in the skin tissues to be subjected to stretching. In particular, these engaging elements are shaped like needles  22  having a proximal portion  24  perpendicular to the body of the respective jaw  10 ,  12  and a distal portion  26  inclined with respect to the general plane of this body, advantageously at an angle of between 0° and 50°. The needles  22  may or may not be hollow on the inside. 
     The first jaw  10  has a front edge which faces towards the front edge of the second jaw  12  and has a socket  28  into which is inserted the first end of the strip  14 , which is fixed permanently in said socket by conventional methods, for example by means of bonding or mechanical fastening devices. 
     The second jaw  12  has a front edge with a fissure  30  which faces towards the front edge of the first jaw  10 . The mid portion of the body of the jaw  12  is provided with a through-opening  32 , which communicates with the fissure  30  and has side edges in which respective slots  34  are present, by way of which the opening  32  communicates with the outside even at the sides of the body of the jaw  12 . In embodiments of the invention which are not shown, the opening  32  may also not be a through-opening and thus affect only one face of the body of the jaw  12 . Each slot  34  has a front portion  36  having a substantially rectangular section and a rear portion  38  having a rounded section which is larger than the front portion  36 . 
     A pivot  40  passes through the slots  34  and the opening  32 , lying in the general plane of the body of the jaw  12  and perpendicularly with respect to the longitudinal axis of the strip  14 . The pivot  40  ( FIG. 6 ) has respective heads  42  at the ends, a mid portion  44  having a substantially circular cross section and intermediate portions  46  between the mid portion  44  and each head  42 , having a cross section with sharp corners, in particular square corners. The intermediate portions  46  of the pivot  40  are placed in the respective slots  34 , the mid portion  44  in the opening  32  and the heads  42  on the outside of the body of the jaw  12 . The height of the intermediate portions  46  of the pivot  40  corresponds substantially to that of the front portion  36  of the slots  34 , so as to make it possible for the pivot  40  to slide within the slots  34 , but not to rotate, as will be described in detail hereinbelow. 
     The pivot  40  as a whole constitutes a single rigid body which can be monolithic or can be obtained by assembling a number of different parts, for example by inserting the distal ends of the intermediate portions  46  with an interference fit into cavities made in the respective heads  42 . The pivot  40  can be made of any desired material suitable for use in the medical field. 
     The strip  14  is passed in the fissure  30 , wound around the mid portion  44  of the pivot  40  and is again passed through the fissure  30 , whereby the second end thereof freely protrudes from the second jaw  12 . 
     This method for association of the strip  14  with the second jaw  12  makes it possible to continuously regulate the size of the instrument in accordance with the extension of the wound of which the margins have to be brought close together. For this purpose, it is necessary to position the pivot  40  such that the intermediate portions  46  thereof pass through the rear portions  38  of the slots  34  having an enlarged section. In this way, the pivot  40  can rotate freely about its own longitudinal axis, making it possible for the strip  14  to slide about the pivot  40  until—once the desired sliding corresponding to a certain distance between the jaws  10 ,  12  has been effected—the pivot  40  is moved forwards into the front portions  36  of the slots  34  in which it can no longer rotate. In this position, the strip  14  is locked between the pivot  40  itself and the front wall of the opening  32  above and below the fissure  30  and can no longer slide with respect to the pivot  40 . 
     This effects a preliminary regulation of the distance which separates the jaws  10 ,  12  in a position of rest, adapting said distance to the size of the wound to be treated, and the instrument can be installed. For this purpose, the jaws  10 ,  12  are then pushed apart, so as to subject the strip  14  to a traction force, and the distal ends of the needles  22  are engaged in the skin tissues at the edges of the wound to be treated. The application of the correct traction force is made easier by the marks  16  placed on the strip  14 . In the absence of traction, indeed, these marks  16  have a rectangular shape, which tends to become square under the action of force. The transformation of the shape of the marks  16  into a square—which can easily be detected by any operator—thus indicates that the traction to which the strip  14  is subjected is correct. The elastic return force exerted by the strip  14  is applied to the distal ends of the needles  22 , which subject the tissues in which they are inserted to stretching, so as to make it easier for the margins of the wound to be brought close together. 
     In principle, therefore, the operation of the instrument according to the invention is based on the principle of extending a tissue subjected to stretching/expansion. 
     The use of the instrument is directed in particular to making it possible to directly close, by means of stitching, wounds of which the margins cannot be brought close together directly, disregarding the mobilization of edges by means of plastic surgery techniques. 
     Clearly, without departing from the principle of the invention, the details of construction and the embodiments may differ considerably from those described purely by way of example, without thereby departing from the scope of the invention as defined in the appended claims.