1: General Considerations

General Considerations

Attributes of an Acceptable Approach to a Bone or Joint

The bones and joints must be exposed in a manner that ensures the preservation of the anatomic and physiologic functions of the area invaded. Major blood vessels, nerves, ligaments, and tendons must be avoided or protected. Maximal use must be made of muscle separation, with incision of muscles being avoided whenever possible. Transection of muscle bellies must be kept at an absolute minimum; tenotomy or osteotomy of the muscles at their origin or insertion is much preferred. Skin incisions must be made in such a manner that the vascular supply to the wound margins is not impaired and so that underlying implants such as bone plates do not create tension on the skin closure. No pedicles or sharp angles should exist in the incision because these points commonly undergo avascular necrosis and may produce wound breakdown, infection, or excessive scar formation. A cosmetically acceptable scar should be one goal of the surgery.

In general, the procedure should not add unnecessary trauma to that which the injured area has already sustained. Although the incision may be longer, an adequately large exposure is, in the final analysis, less traumatic than a smaller exposure. With the smaller approach, the surgeon tends to exert excessive pressure when retracting muscles, which directly injures the muscle and also impairs circulation to the area.

Factors to Consider When Choosing an Approach

The Area to be Exposed

The problem of choosing the best approach is easily solved in some instances. For example, there is only one logical way to expose the midshaft of the femur (see Approach to the Shaft of the Femur, Plate 77), and therefore the decision is easily made. Other regions do not lend themselves to such clear-cut answers. In some instances, the choice is purely a matter of the surgeon’s personal preference. The hip joint perhaps illustrates this best, there being many choices for exposure of this general region. Ultimately, it rests with the surgeon to evaluate all approaches and to adapt those most suitable.

The exposure required for bone plating is generally more extensive than for bone-pinning techniques. In this instance, it may be useful or necessary to combine two or more of the approaches illustrated. This is discussed further in the section “The Type of Fracture or Luxation.”

Minimally Invasive Exposure of Bones and Joints

With the trend in fracture surgery toward “biological fracture repair,” there is a much greater recognition of the importance of preservation of soft-tissue attachments, bone blood supply, and fracture hematoma, all of which have a critical role in the early phase of bone healing. This evolution has been facilitated by the greater availability of preoperative computed tomography imaging for fracture planning, intraoperative fluoroscopic imaging, indirect fracture reduction techniques, and new fracture fixation implants.

Perfect anatomic reduction of intra-articular fractures is possible with the aid of intra-operative fluoroscopic imaging, and therefore a complete open approach to the joint might not be required. This allows insertion of Kirschner wires and lag screws through small “stab incisions” to complete the fracture stabilization. Moreover, indirect reduction techniques can be applied to diaphyseal fractures to obtain overall alignment without the need for anatomic fracture reduction. For diaphyseal fracture stabilization, the technique of minimally invasive plate osteosynthesis can be applied. Small skin incisions are made in the proximal and distal metaphyseal regions of the bone, without exposing the fracture site directly. Afterward the two incisions are connected by a longitudinal epiperiosteal tunnel, so that the bone plate can be slid through the tunnel, across the fracture site (e.g., see Minimally Invasive Approach to the Shaft of the Humerus, Plate 36).

The minimally invasive approach to fracture repair is more technically demanding than traditional open reduction and internal fixation. The surgeon should have additional training and experience to perform it well. The availability of intraoperative fluoroscopic imaging is important for the evaluation of the fracture reduction and implant position. However, surgeons should be ready to convert from a minimally invasive approach to an open approach if the procedure becomes too difficult. Timely conversion to an open approach is important if the surgeon is to avoid excessive exposure of surgical personnel and the patient to radiation, undue damage to the soft tissues, inadequate fracture alignment, and technical mistakes in implant placement resulting in poor fixation.

Breed, Size, and Conformation of the Animal

The region of the hip may also be used to illustrate the relationship of the patient’s physique to the problem. We are speaking here not only of the size, but also of the body conformation and the degree of obesity of the patient. Chondrodystrophoid breeds are a particular challenge. The shapes and contours of many muscles in the limbs are distorted, and close attention is required to ensure that you end up where you really want to be.

The obese patient is also a serious problem for the surgeon, for it is difficult to identify muscles when their fascial sheaths are obscured by fat. The only help for this problem is to dissect fat off the deep fascia with the skin to allow better visualization of the underlying muscles. A longer skin incision may be required to achieve adequate exposure at the level of the bones.

Associated Soft-Tissue Damage or Infection

When a choice of approaches exists, the extent and location of associated injuries can influence the choice of approach. Bruising and hematoma formation make the identification of fascial sheaths and muscle bellies more difficult. Furthermore, fractures and luxations result in changes in orientation and position of the muscles in the region. An attempt is always made to avoid exposing bone through an existing skin wound or sinus tract. The reason for this is to prevent the transfer of infected or contaminated material to the bone and the surrounding deep structures. The same reasoning is applied to open fractures of more than a few hours’ duration. When there is no alternative to approaching through such an area, the traumatic wound must be meticulously débrided and lavaged. It is then prepared again for surgery and redraped, and fresh gloves and instruments are used for the fracture repair.

Aseptic Technique

The keystone on which success or failure of open bone and joint surgery rests is meticulous devotion to the ritual of aseptic technique. True enough, gentle handling of tissues and an anatomically sound approach are of utmost importance, but they go for naught in the presence of wound infection or osteomyelitis. The incidence of these sequelae can be reduced to less than 3% by attention to rigid asepsis and the proper use of antibiotic drugs. In clean cases, where no contamination or infection is suspected, an appropriate dose of a bactericidal antibiotic (e.g., a beta-lactam such as a cephalosporin or amoxicillin with clavulanic acid) is administered intravenously at the time of anesthesia and repeated in 90 minutes. It must be understood that to be effective at the time of surgery, the antibiotic drug must be administered preoperatively with sufficient time to allow effective serum levels of the drug to be present. Antibiotic medications are not administered postoperatively unless contamination or infection is suspected, or serious tissue damage is noted during surgery. In such cases, antibiotic medications are continued for at least 7 days postoperatively. Choice of antibiotic drug used long term should be based on culture and sensitivity of samples taken during surgery.

A detailed discussion of the methods of sterilization of packs, gowns, and other supplies is beyond the scope of this book. In general, autoclaving at 250° F and 15-lb pressure and with a contact time of 12 to 15 minutes is the most practical way of sterilizing instruments and cloth materials such as drapes and gowns. Sterilizer indicators1 that undergo a color change when exposed to proper sterilization conditions should be used in every pack. Total time in the autoclave is different from contact time; total time is that which is sufficient for steam penetration of the largest pack for the minimum contact time of 12 to 15 minutes. Sterilizer indicators are the only means of establishing the correct total time. Ethylene oxide is also a very useful sterilization method because it allows sterilization of items that would be damaged by heat and therefore allows the use of electric drills and other hardware store items in surgery.

Proper skin preparation, positioning, and draping of the patient are critical elements of aseptic technique that are commonly neglected. For all procedures on limbs, including the hip or shoulder region, a stockinette draping procedure is advised. Draping the whole limb in a sterile, double-thickness cotton stockinette allows the limb to be handled by the surgeon and manipulated in any way necessary. When reducing fractures, the need for alignment of the total limb in all planes is obvious. When reducing luxations, the whole limb can be used to supply additional leverage or torque to aid in reduction.

The limb is clipped circumferentially from the inguinal or axillary area with a #40 blade and electric clippers to some distance distal to the proposed skin incision. For approaches to the hip or shoulder, the clipping extends proximally to the midline of the back. When the approach is below the elbow or stifle, the clipping usually starts just above the toes and extends proximally only to the elbow or stifle region. Adhesive tape is applied to the toes or foot to form a stirrup from which the leg can be suspended. The remaining unclipped area is covered with gauze or a latex or plastic glove and adhesive tape (Figure 1A and B).

The patient is next placed on the surgery table with the clipped leg uppermost and the leg suspended by adhesive tape attached to the stirrup and to an infusion stand or a hook in the ceiling (Figure 2). Abduction of the limb to a 45- to 60-degree angle from midline is adequate to allow skin disinfection and draping.

Povidone-iodine2 (“organic iodine”) or chlorhexidine3 preparations have proved most efficacious for disinfection of the patient’s skin. Using sterile gauze sponges immersed in surgical scrub preparation diluted 50% with sterile saline solution or water, the patient’s skin is scrubbed, starting in the area of the incision and working outward to the limits of the clipped area. After 1 minute of scrubbing, the suds are wiped off with dry, sterile sponges. Again, the wiping starts in the area of the incision and proceeds toward the periphery of the clipped area. This cycle is repeated 5 times, and after the final rinse the whole area is sprayed or wiped with povidone-iodine or chlorhexidine solution, or 70% to 80% isopropyl alcohol, which is allowed to remain and dry on the skin. Povidone-iodine and chlorhexidine surgical scrubs are also highly effective for the scrubbing of the surgeon’s hands.

The patient is now ready for draping as soon as the surgeon or assistant is gowned and gloved. Four sterile towels are first placed around the leg at the inguinal or axillary region (Figure 3). The circulating assistant now grasps the leg on the unprepped area and cuts the suspending tape while holding the leg in position. The surgeon grasps the foot through a sterile towel that has been partially rolled (Figure 4A) and then wraps the towel around the unprepped area while holding the limb up and away from the table. The towel is folded over the toes and secured with towel clamps (Figure 4B). Now the rolled stockinette is placed over the foot (Figure 4C) and unrolled down the leg, taking care not to touch any unprepped areas in the process. When the stockinette meets the towels, the two are joined together and attached to the skin with towel forceps (Figure 5A). A method for the hip or shoulder region is shown in Figure 5B and C. (The cotton gauze stockinette is previously prepared and sterilized. Cut the stockinette twice as long as the leg, using a suitable diameter for the thigh or brachium. Pull half the stockinette inside the other half and tie or tape the cut ends together to make an elongated bag. Roll the uncut end toward the closed end as if rolling a stocking. Wrapping and sterilizing complete the preparation. Alternatively, a presterilized impervious stockinette4 can be used.)

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Mar 31, 2017 | Posted by in SUGERY, ORTHOPEDICS & ANESTHESIA | Comments Off on 1: General Considerations

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