Patent Application
20160331388
Throughout this application various publications are referred to in superscripts. Full citations for these references may be found at the end of the specification before the claims. The disclosures of these publications are hereby incorporated by reference in their entireties into the subject application to more fully describe the art to which the subject application pertains.
Midline axial sternotomy, first described by Milton in 1887 and reintroduced by Julian and Associates in 1957,1 is the most frequently performed osteotomy worldwide2, and is the preferred technique for exposure of the heart and great vessels. Despite its advantages, sternal wound complications may occur. Sternal dehiscence can occur in 0.2% to 5% of patients due to poor wound healing and surgery related factors.3-5
Sternal dehiscence and deep sternal wound infection (DSWI) are post-sternotomy wound complications that result in significant morbidity and mortality as well as prolonged hospital stay and increased cost to patients who undergo cardiac surgery. The reported prevalence of this complication ranges from 1-5% with reported associated mortality of up to 25%.6,7 While relatively rare, when they do occur these complications can be severe and costly.
Numerous preoperative and operative risk factors have been identified as predictors of DSWI following cardiac surgery. These include obesity, diabetes mellitus, chronic obstructive pulmonary disease, smoking, steroid use, New York Heart Association functional class IV, osteoporosis, immunosuppression, and previous sternotomy. Operative risk factors include bilateral internal mammary artery harvest, prolonged cardiopulmonary bypass time, and transverse sternal fractures.8 Additionally, patients with multiple known risk factors or off midline sternotomy have been identified as high risk for sternal dehiscence.9,10
Primary reinforcement, an alternative technique to traditional closure by wire circlage, has been advocated for high-risk patients. Primary sternal plating, stainless steel coils, cables, or recently, a sternal synthesis device are cited as increasing sternal stability and thereby potentially reducing wound infection rates.9,10 The decision to employ alternative techniques and materials depends on the surgeon's ability to identify high risk patients who would benefit from such primary reinforcement. However, alternative techniques to prevent faulty sternotomy have not been thoroughly addressed in the literature. There are no identified patents that address the issue of asymmetric osteotomy of the sternum with a cutting guide. The present invention addresses the need for improved treatment procedures and apparatus.
Systems and methods are described for a sternal osteotomy guide and sternal fixation system. Preferably, a sternal fixation system includes one or more non-bioresorable intra-sternal shims, one or more tie members, one or more pairs of brackets, and, optionally, a ratchet gun. Preferably, the shim is configured to be placed between sternal halves and to provide anteroposterior stability once the sternal halves have been pulled together. Preferably, the shim has a relatively thicker or wider center portion than its lateral sides. Preferably, an elongated tie member is attached to or passes through the shim. Preferably, the tie has a first end portion that includes a first gear rack on a surface thereof, and a second end portion that includes a second gear rack on a surface thereof. Preferably, teeth forming the first and second gear racks slope in opposing directions. Preferably, the pair of brackets are configured to distribute pressure at a cortical interface thereof and each pair includes a central ratcheting mechanism operable to interface with the first or second tie gear racks. Preferably, the ratchet gun provides uniform tightening of the pair of brackets.
Preferably, the sternal cutting guide comprises a cutting slot adjustable in the cranio-caudal direction of the sternum, wherein the cutting slot allows passage of a sternal saw; hooks for fixing the cutting guide to a patient; and optionally, drilling eyelets for drilling at multiple positions on both sides of the sternum.
The devices described herein can be used in methods of fixating the sternum of a patient following sternal osteotomy where the methods include creating a midline sternal osteotomy; drilling holes in the anterior sternal cortex for passage of shim ties; placing one or more non-bioresorbable intra-sternal shims between halves of the cut sternum; passing needles attached to the shim ties from intramedullary to extracortical portions of the sternum; removing the needles from the shim ties leaving a portion of the shim tie protruding from the sternum; positioning on each side of the sternum one of a pair of brackets on the ties for each shim; and tightening each pair of brackets using the ratchet gun, thereby fixating the sternum of the patient following sternal osteotomy.
Systems and methods are described for a sternal osteotomy guide and sternal fixation system. The purpose of the sternal osteotomy guide and sternal fixation system is to rigidly fix the hemi-sternal bones, providing both transverse compression and anteroposterior stability. The fixation method must allow rapid re-entry into the chest in the event of a post-operative, intra-thoracic catastrophe. Total time for creation of the midline sternotomy and closure using the most commonly employed current methods is approximately 10-15 minutes. Any technique that replaces these methods must be as fast or faster, relatively inexpensive, and provide fixation at least as efficiently. An ideal solution would not require the use of devices or techniques overtly foreign to the cardiac surgeon. An ideal method would provide the surgeon with uniformity of compression and minimal foreign material, case-to-case.
The sternal fixation system described in this application addresses major points of weakness in the current methods. First, a reusable, adjustable cutting guide is used to create a midline osteotomy, thereby reducing the risk of DSWI due to asymmetric osteotomy. This same cutting guide is used to pre-drill the holes in the anterior sternal cortex for passage of the shim ties at the completion of the procedure. Once the procedure is complete, needles attached to the shim ties are passed from intramedullary to extracortical and then cut off, leaving only the zip-tie portion of the shim tie sticking out of the antero-lateral cortex of the sternum. A sternal bracket is then slid down, flush to the sternum on the non-surgeon side of the table. The surgeon then uses a calibrated gun to fix a second bracket also flush to the sternum on his or her side of the table. The shims through which the ties pass are intra-sternal.
Preferably, the sternal fixation system includes a non-bioresorbable intra-sternal shim, a tie member, a pair of brackets and, optionally, a ratchet gun. The shim can be configured to be placed between sternal halves and to provide anteroposterior stability once the sternal halves have been pulled together. The shim can have a relatively thicker center portion than its lateral sides. The tie member can be attached to or passed through the shim. A first end portion of the tie member can include a first integrated gear rack on a surface thereof. A second end portion of the tie member can include a second integrated gear rack on a surface thereof. Preferably, the teeth forming the first and second integrated gear racks slope in opposing directions. Preferably, brackets are configured in pairs to distribute pressure at a cortical sternal interface thereof, and each pair includes a central ratcheting mechanism operable to interface with the first integrated gear rack or the second integrated gear rack. Preferably, the ratchet gun provides uniform tightening of the pair of brackets.
Preferred, non-limiting features of the preferred sternal cutting guide and sternal fixation system are described in the following.
Sternal Cutting Guide
Sternal Fixation System
Asymmetric osteotomy of the sternum is a major cause of DSWI (deep sternal wound infection) which, in turn, is a major cause of post-cardiac surgery morbidity and mortality as well as cost to the health care system. Using the sternal osteotomy guide to guide a midline osteotomy, the complications from DSWI should decrease. The present systems and methods include the following advantages:
This application claims the benefit of U.S. Provisional Patent Application No. 62/103,257, filed on Jan. 14, 2015, the content of which is herein incorporated by reference into the subject application.
| Number | Date | Country | |
|---|---|---|---|
| 62103257 | Jan 2015 | US |
