A thorough history and physical examination are required before performing the indicated TKA. Although emphasis is often placed upon the patient’s cardiac or pulmonary status, equally important is the wound healing potential of the individual patient. Of utmost importance is the vascular status of the involved limb. Because of the ambulatory limitations of an arthritic knee, claudication symptoms may not be present despite significantly impaired blood flow. Therefore, physical examination should include evaluation of the skin around the knee and a thorough vascular examination of the limb should be performed. Atrophic changes, decreased hair growth, inadequate pulses, and presence of skin discoloration should be noted. The preoperative X-rays may also provide a clue of vascular compromise through the identification of calcified blood vessels and evidence of arterial sclerosis. A vascular surgery consult may be necessary to evaluate for the potential of vascular reconstruction. Changes in normal TKA protocols may also be required, for example, the use of an arterial tourniquet may be contraindicated or preoperative intravenous heparin may be required to aid in maintaining the patency of previously reconstructed vessels. In other instances, preoperative arteriograms may be required to document adequate blood flow or normal anatomy as is the case in congenital absence of the patella.

Large vessel arterial calcifications identified on preoperative radiographs are of important significance for ischemic complications in patients undergoing a TKA such as an increased risk for protracted wound healing and arterial thrombosis. If identified, it is important to consider performing a TKA without the use of a tourniquet. There is contentious debate in literature as to whether the use of a tourniquet will adversely affect the patient’s TKA. Rupture of preexisting plaques, potential occlusion of peripheral arteries and possible intimal tear of large vessels is a concern; however, many studies have shown no deterioration in ankle-brachial indices (ABIs) of patient with peripheral vascular disease with the use of a tourniquet.⁶

Another factor to consider before surgery is anemia. Although debatable, anemia has been thought to play a role in wound healing,⁷,⁸ with wounds in patients
with a hematocrit less than 35% thought to be in jeopardy⁹ because of a decrease in oxygen tension at the skin edges of the surgical wound.⁹,¹⁰ Heughan et al concluded that anemia is well tolerated and that mild to moderate anemia does not adversely impair oxygen delivery in wound healing¹¹; however, this does not mean that preoperative anemia should be ignored. In fact, it is now protocol in our institution to evaluate a patient’s hemoglobin level before performing the indicated TKA and those with preoperative anemia receiving erythropoietin supplementation before surgery. Patients with hemoglobin levels of more than 10 and less than 13 receive 40,000 units of erythropoietin for 1 to 3 weeks before surgery in conjunction with iron supplementation (Fig. 55-2). This approach is an attempt to maximize preoperative blood levels, thus limiting exposure to allogeneic transfusions. Furthermore, by limiting transfusion requirements, there may also play a role in avoiding wound complications and surgical site infections.¹²

Preexisting medical conditions should also be of concern to the treating physician. Not only should conditions such as chronic venostasis be noted on physical examination, but also a history of venous ulceration. Diagnosis of human immunodeficiency virus infection should also be recorded.¹³ Lehman et al noted increased infection in human immunodeficiency virus patients undergoing total joint arthroplasty.¹⁴ Although human immunodeficiency virus should not prevent TKA, discussion should take place before TKA regarding increased evidence of wound failure potential.

A patient’s nutritional status may play a role in wound healing potential. Albumin levels (less than 3.5 g per dL) as well as total lymphocyte count (less than 1500) may make a patient more prone to wound failure.¹⁵,¹⁶ Once a decreased nutritional status is documented, these deficiencies should be corrected before surgery. Furthermore, it is important to realize that obese patients can demonstrate laboratory criteria of malnutrition and potential wound complications,¹⁷,¹⁸,¹⁹,²⁰ due to excess caloric intake of nutrient-poor foods. Moreover, surgical exposure in a morbidly obese patient is technically more difficult because of the abundant adipose tissue as well as physical limitations on knee flexion and joint exposure. Because
of these limitations, more vigorous skin retraction may be required. The relationship between body mass index (BMI) and prosthetic joint injection from wound issues has been well studied in the literature.¹⁸,²¹ Obese patients have demonstrated increased wound drainage postoperatively.²²,²³ In 2014, a prospective study by Dowsey and Choong demonstrated that patients with a BMI >40 kg/m² has a nine-time greater risk of periprosthetic joint infection (PJI).²⁴ Despite these findings, obesity is not a contraindication for TKA. Stern and Insall²⁵ showed no difference in wound complications with TKA and obese patients. This same cohort of patients was examined at a 10-year follow-up, and once again, no increase in wound difficulties was noted.²⁶ It should be mentioned that even though anthropometric measurements have been established for malnutrition, their use is still limited with no standardized parameters. An emphasis should be on proper tissue handling in the obese patient during surgery. Heavy-tooth forceps and crushing clamps should be avoided, as should excessive skin retraction. Retraction should be intermittent, when applied, to avoid local edema, which may complicate blood flow to the wound edges.

One modifiable risk factor that can be controlled is cigarette smoking. By inhibiting skin microcirculation, cigarette smoking can compromise skin circulation.²⁷,²⁸,²⁹ Furthermore, multiple studies describe the detrimental effects of smoking with its increase in reoperation rates, implant loosening, deep infections, and mortality.³⁰ Because of the lengthy vasoconstrictor effects, cessation of smoking must occur more than 4 weeks before surgery for some benefit to occur.²⁷,²⁸,²⁹ After cessation for 4 weeks, the patient’s metabolic and immune functions start to normalize, which helps decrease the morbidity and mortality compared to a patient that continues to smoke.³¹,³²,³³ Postoperatively, the patient should continue to be a nonsmoker by attending smoking cessations programs or counseling sessions. These programs have shown to reduce the rate of smoking before and up to 6 months after surgery which can help reduce the incidence of post-operative complications.³⁴,³⁵,³⁶

Certain medical comorbidities may interfere with wound healing. Wong et al demonstrated delay in wound healing in the diabetic patient, with increased wound separation, erythema, and swelling noted.³⁷ These healing delays may be secondary to delayed collagen synthesis that results in delayed wound tensile strength. Peripheral vasoconstriction in both large and small vessels may also contribute. Wilson et al found no increased risk for infection after TKA in diabetic patients.²² Controversy also exists with regard to wound healing and rheumatoid arthritis patients. Although Wong and associates³⁷ found a 30% complication rate in rheumatoid arthritis compared with osteoarthritic patients, this conflicts with the data of Garner and associates,³⁸ in which no delay in wound healing was noted. It is unclear whether corticosteroids used to treat rheumatoid arthritis interfered with wound healing rather than the disease itself. Wilson et al demonstrated wound healing difficulty in rheumatoid arthritis patients but only in those treated with corticosteroids.²² No difference in wound healing was reported when corticosteroids were not used. It has been our experience that rheumatoid arthritis skin is fragile, and caution should be exercised in tissue handling as well as with the placement and removal of adherent drapes.

Recognition of systemic factors before surgery can aid in their correction, thus improving wound healing potential.

Wound healing potential includes not only the location of previously placed skin incisions but other factors such as the degree of deformity, rotational element of deformity, skin adherence, or history of previous trauma such as burns. Multiple studies have shown increased wound healing problems in knees with numerous incisions.³⁹,⁴⁰ Problems arise when an avascular bridge exists between the new and previous incision. Not all complications occur in knees with multiple incisions. Any knee with decreased subcutaneous tissue, in particular the hypodermis layer which contains loose connective tissue and fat lobules, has decreased skin elasticity, which may put a wound at risk. This includes patients with significant long bone trauma or a history of burns. Large rotary deformities may also place a patient at risk for wound failure, with inadequate skin available for closure after the rotary and varus-valgus deformities are corrected.

Although local factors can be identified but not always modified, surgical technique factors can be modified to enhance wound healing potential. To begin, an adequate skin exposure should be chosen. Even though the patient and physician want to avoid long incisions, the incision should be extensive enough to avoid excessive skin retraction. In addition, the skin should be handled gently to preserve the subcutaneous fascial layer. Large flaps should be avoided, and no lateral flaps should be required though occasionally adhesions may be present in the subcutaneous layer of valgus deformities that require release. This should be done only on an as-needed basis. If a flap becomes necessary, it should be minimal and as deep as possible to help preserve the blood flow to this dermal plexus.

A lateral release during a TKA is not a benign procedure. Many studies have shown that patients having a lateral release have a decrease in the skin oxygen at the wound healing edges resulting in wound healing complications.¹⁰ With the use of proper component position, appropriate patella thickness, and correct component
rotation, the lateral release rate can be decreased. Despite this, a lateral release may be required that can result in the disruption of the superior genicular vessels. Johnson and Eastwood¹⁰ noted a decrease in skin oxygen tension when the lateral release was performed. As a result of this lateral release, the rate of superficial drainage and infection rates were also increased in those patients. At the author’s institution, if a lateral release is required, a lateral flap is avoided. We prefer an all-inside approach from the middle flap to help seal the postoperative hematoma inside the joint. If a large flap is performed in conjunction with a lateral release, the postoperative hematoma is allowed egress through the lateral release site underneath the subcutaneous level. This may present increased pressure on the skin and may lead to prolonged postoperative drainage, and in these cases, a subcutaneous drain should be considered.

With no previous incision, the midline approach is preferred. Johnson⁴¹ and Dennis⁴² evaluated skin oxygen tension for a variety of incisions (midline, medial parapatellar, medial curved) and concluded that a medial-side circulation predominance existed in the cutaneous circulation. The lateral aspect of the skin incision demonstrated lower skin oxygen tension throughout the postoperative period. By postoperative day 8, preoperative skin oxygen levels returned to normal, which is another factor why a lateral incision should be avoided. Previously placed skin incisions make initial incisions more difficult. If avoidance is not possible, we attempt to incorporate the new incision within the old. If parallel incisions exist, choose the most lateral one. Transverse incisions can be crossed, in most instances at 90° angles with really no threat to the local skin blood supply.²,⁴²,⁴³ If a wide scar with minimal subcutaneous tissue is present, the knee may be at risk because it disrupts the underling dermal plexus.⁴² If this occurs, treatment should include soft tissue expanders. Of importance during surgical technique is the distance between previous incisions. If the skin bridge is less than 2.5 cm, tissue expanders should be considered. Skin bridges of less than 2 cm may result in tissue necrosis between the previous incisions and the new incision (Fig. 55-3). Other technical factors include repair of the medial retinaculum. It is commonplace in our institution to perform flexion of the knee after closing the retinaculum to evaluate the suture integrity. If the sutures break under direct visualization, these can be replaced before closure of the more superficial layers. If this is difficult at the time of surgery, new skin closure systems are available that may be helpful (Fig. 55-4). Currently, a variety of skin closure methods are being used. Surgeons can choose between skin staples, monocryl, and monoderm (quill suture device). Utilization of skin glue after a monoderm skin closure is routine practice in our institution.