A new method of sternal approximation

A review of sternal closure techniques

Sternotomy and sternal closure occur prior to and post cardiac surgery, respectively. Although post-operative complications associated with poor sternal fixation can result in morbidity, mortality, and considerable resource utilization, sternotomy is preferred over other methods such as lateral thoracotomy. Rigid sternal fixation is associated with stability and reduced incidence of post-operative complications. This is a comprehensive review of the literature evaluating in vivo, in vitro, and clinical responses to applying commercial and experimental surgical tools for sternal fixation after median sternotomy. Wiring, interlocking, plate-screw, and cementation techniques have been examined for closure, but none have experienced widespread adoption. Although all techniques have their advantages, serious post-operative complications were associated with the use of wiring and/or plating techniques in high-risk patients. A fraction of studies have analyzed the use of sternal interlocking systems and only a single study analyzed the effect of using kryptonite cement with wires. Plating and interlocking techniques are superior to wiring in terms of stability and reduced rate of post-operative complications; however, further clinical studies and long-term follow-up are required. The ideal sternal closure should ensure stability, reduced rate of post-operative complications, and a short hospitalization period, alongside cost-effectiveness.

Late complications of chest wall reconstruction: management of painful sternal nonunion

Although rare, sternal nonunion after median sternotomy or traumatic injury is associated with a high rate of morbidity. Pain and sternal clicking are two of the most common complaints and reasons these patients seek evaluation and treatment. Diagnosis of sternal nonunion is based on a thorough history and physical examination and can be confirmed with subsequent radiographic imaging. The treatment for symptomatic sternal nonunion requires stable fixation of the bony fragments and chest wall after the debridement of all nonviable bony and soft tissue by the cardiothoracic or reconstructive surgery team. Multiple fixation techniques have been described and incorporate a wide variety of materials including combinations of wires, cables, pins, bands, staples, and plates. Most recently, several new commercially available plating systems have demonstrated low recurrence and complication rates and resolution of the patient's symptoms on follow-up evaluation. Included in this review are three cases demonstrating the management of symptomatic sternal nonunion using these new techniques and review the history, diagnosis, risk factor, and classification, as well as several of the previously described fixation methods.

Mechanical analysis of midline sternotomy wound closure

OBJECTIVE

Unstable median sternotomy closure can lead to postoperative morbidity. This study tests the hypothesis that separation of the sternotomy site occurs when physiologic forces act on the closure.

METHODS

Median sternotomy was performed in 4 human cadavers (2 male) and closed with 7 interrupted stainless steel wires. The chest wall was instrumented to apply 4 types of distracting force: (1) lateral, (2) anterior-posterior, (3) rostral-caudal, and (4) a simulated Valsalva force. Forces were applied in each direction and were limited to physiologic levels (< 400 N). Four sets of sonomicrometry crystals were placed equidistantly along the sternum to measure separation at the closure site.

RESULTS

Sternal separation occurred as a result of the wires cutting through the bone. Less force was needed to achieve 2.0-mm distraction in the lateral direction (220 +/- 40 N) than in the anterior-posterior (263 +/- 74 N) and rostral-caudal (325 +/- 30 N) directions. More separation occurred at the lower end of the sternum than the upper. During lateral distraction, xiphoid and manubrial displacement averaged 1.85 +/- 0.14 and 0.35 +/- 0.12 mm, respectively. Anterior-posterior distraction caused 1.99 +/- 0.04-mm xiphoid displacement and 0.26 +/- 0.12-mm manubrial displacement. During a simulated Valsalva force, more separation occurred in the lateral (2.14 +/- 0.11 mm) than in the anterior-posterior (0.46 +/- 0.29 mm) or rostral-caudal (0.25 +/- 0.15 mm) directions.

CONCLUSIONS

These data suggest that sternal dehiscence can occur under physiologic loads and that improved sternal stability may be readily achieved via mechanical reinforcement near the xiphoid. Closure techniques designed to minimize wire migration into the sternum should also be developed.

Improved sternal closure using steel bands: early experience with three-year follow-up

BACKGROUND

Use of stainless steel wires in median sternotomy closure is at times associated with serious complications. In view of this, the efficacy and safety of a stainless steel band designed for fixation and approximation of the sternum in cardiothoracic procedures was evaluated in a prospective, randomized study.

METHODS

Forty-eight patients undergoing open heart operations that involved a median sternotomy were studied. Group I (n = 21) was closed with four to six steel bands, and group II (n = 27) with six to eight standard stainless steel wires. The average age of the patients and the risk factors predisposing to dehiscence were similar in both groups.

RESULTS

One postoperative death occurred in each group due to cardiac failure. In group I, the mean length of the postoperative hospital stay was 10.2 +/- 1.76 days (+/- 2 standard errors), whereas in group II the mean was 13.9 +/- 3.4 days (+/- 2 standard errors). Banded patients complained less of postoperative pain, although statistical significance was not achieved. No problems arose in either group during the 3-year follow-up.

CONCLUSIONS

The steel bands, compared with wires, provided not only effective fixation, but a reduction in both postoperative pain and postoperative hospital stay. The band is now being studied in a larger group of patients to evaluate the incidence and type of complications associated with its use, as well as length of postoperative hospital stay.

Biomechanical study of sternal closure techniques

Median sternotomy is the most commonly used incision in cardiothoracic surgery. Closure of this incision is usually performed with parasternal wires, but alternate techniques have been proposed to improve closure stability. This study compares biomechanical stability of standard wire (No. 5 stainless steel) with that of three types of band closure: 5-mm Mersilene ribbon, 5-mm stainless steel band, and 5-mm plastic band. Eight bisected cadaver sterna were reapproximated using each method of sternal fixation and tested for biomechanical stability using an MTS Bionix 858 Biomechanical Tester. Loads of 50, 100, 150, and 200 Newtons (1 Newton = 1 kg.m/s2) were applied as a distracting force across the closure. A linear regression line of displacement as a function of increasing load was determined for each closure method; the slope of this line is inversely proportional to fixation stability. Displacement and load correlated linearly for each closure (r = 0.99). Mean slopes were 0.012 mm/Newton (95% confidence limits, 0.0098 to 0.0142 mm/Newton) for No. 5 stainless steel wire, 0.014 mm/Newton (95% confidence limits, 0.0118 to 0.0162 mm/Newton) for plastic band, 0.017 mm/Newton (95% confidence limits, 0.0148 to 0.0192 mm/Newton) for Mersilene ribbon, and 0.017 mm/Newton (95% confidence limits, 0.0148 to 0.0192 mm/Newton) for 5-mm steel band. No. 5 stainless steel wire provided the most stable closure, although statistical significance was achieved only in comparison with Mersilene ribbon and stainless steel band (p < 0.05). The superior stability of stainless steel wire closure may be due to tightening of the wires by twisting, which results in more tension across the reapproximated sternal halves than with other methods.

[Experimental studies of stabilization of refixation following median sternotomy]

So far several methods have been established for refixing the sternum halves after longitudinal sternotomy like steel wire or steel strap according to Parham. The use of twisted absorbable PDS-strings is new. During experimental investigations in corpse sterna during tension load the different refixing methods were compared. As a result we found an increased tension stability of the sternum refixation as well as the reversibility of suture dehiscences, if occurred, after employment of the elastic PDS-string. Polydioxanon is a suggestive alternative compared with the usual not absorbable materials for refixation of the sternum.

[Closure of median sternotomy with resorbable synthetic sutures]

To date, the refixation of the bone halves after median sternotomy is accomplished with wire, steel bands or thick, not absorbable plastic threads. As the first, we used absorbable synthetic strings in 25 patients. During the absorbtion the development of a very strong bone scar was possible, because the absorbtion lasted very long. The refixation of the sternum in cases of aseptic instability was even possible. So we think to have found another range of application for absorbable synthetic material which recently has been used more and more in several parts of operative medicine, even in hard burdened connective tissue.

Update on sternal osteosynthesis

Interfragmental compression enables primary bone formation in the bone fracture line and results in better and faster contact bone healing. The Controlled Tension Osteosynthesis System is a simple and uniform sternal closure method that makes use of the principles of widely used modern osteosynthesis techniques. A review of tensile tests of currently available sternal closure methods has shown that the wire closure is the weak link in all procedures. An anchor plate has been developed as a more efficient means of wire closure. In contrast to the most commonly used wire twist closure, which has an optimum strength that is only 20% to 33% of the original wire tensile strength, the anchor plate closure retains up to 80% of the wire's tensile strength. Used in combination with a steel alloy wire with a metallurgically increased tensile strength, it results in a sevenfold to ninefold increase in effective fixation stability. A specially designed instrument, the Strainsqueezer, enables easy clinical application of the anchor plate under controlled, standard conditions. The system offers an optimal compression osteosynthesis fixation using a minimal amount of foreign body material (thin, prestressed wire). Its development was based on technical experience gained through 6 years of clinical practice involving 800 sternotomies.

Median sternotomy dehiscence

Sternal dehiscence requiring reoperation occurred in 36 out of 4,531 patients who had a sternotomy incison within an eight-year period. Twisted sternal wire sutures were used for the first four years and a crimped steel plate fixation was used during the second four years with a marked and significant decrease in the incidence of dehiscence from 17 out of 1,000 patients to 3 out of 1,000 patients. Thirty-five of the 36 patients were men, and 4 required reoperation for bleeding. Other factors such as mammary artery dissection, tracheostomy, and body weight of more than 82 kg were not significant. Although infection was noted in 20 patients, it was thought to be secondary. Early reoperation with antibiotic irrigation achieved wound stability in the 34 survivors with only 3 patients requiring additional procedures for chronic osteomyelitis of the sternum.

Thoracic traction for median sternotomy dehiscence

Standard management of median sternotomy dehiscence sometimes fails to achieve lasting reduction and fixation of the sternal halves. An effective method of external thoracic traction that augments internal fixation of the sternal fracture is presented.

Sternal wire closure by an instrumental method

Effective median sternotomy closure requires approximation of the sterum under appropriate tension in an expeditious manner. An instrument has been developed to provide tightening of applied sternal wires, allowing proper tension to be established. After tightening, the twisted wire is automatically trimmed by the instrument. The ease and reproducibility of this wire closure technic has allowed the method to be performed on a routine basis.

Clamp for wire closure of sternum

A modification of the Kocher clamp used for wire closure of the sternum is described. With the clamp applied securely to the individual strands, the wire can be readily twisted; the shorter length of the clamp allows the surgeon a much firmer grip on the wire and saves considerable time during closure.

Sternal staple: simple and rapid device for closure of median sternotomy

A new device for rapid and secure closure of median sternotomy has been developed, clinically proved, and found to be an excellent additional tool for the armamentarium of the thoracic surgeon.

Peristernal closure of median sternotomy using stainless steel bands

Peristernal closure of median sternotomy incisions with interrupted stainless steel bands has proved to be a rapid and safe method for achieving solid internal fixation in approximation of the sternum. The method is particularly useful for obese patients undergoing sternotomy. There have been no instances of wound dehiscence using this technique, and several other advantages over standard forms of sternal closure are apparent. The method is a useful addition to the cardiac surgeon's armamentarium.