A 58-year-old woman complained of progressive left knee pain and giveway for 1 year. She had a history of a motor vehicle accident 19 years previously in which she sustained an open supracondylar femur fracture. This was treated with open reduction and internal fixation. She developed posttraumatic arthritis and underwent a total knee arthroplasty (TKA) about 13 years before presentation. The procedure was complicated by wound healing problems that necessitated débridement and local wound care; ultimately, the wound healed.
Physical examination demonstrated two vertical incisions with multiple smaller transverse scars about the knee ( Fig. 36.1 ). The scar along the proximal aspect of the medial vertical incision was widened. Range of motion of the knee was 0 to 95 degrees of flexion. She had 5 to 8 mm of medial laxity, with an end point, and 5 mm anterior draw at 90 degrees. The medial and lateral joint lines were tender.
Radiographs demonstrated a cemented cruciate-retaining TKA with evidence of asymmetric polyethylene wear and prior internal fixation of a supracondylar femur fracture with a blade plate ( Fig. 36.2 ). The clinical workup was negative for infection.
A revision TKA was planned. Because of concerns about her multiple prior incisions, history of wound healing problems, and potential need for an additional lateral incision to remove the plate and screws along the femur, she was referred to plastic surgery for consideration of tissue expansion before revision TKA. Three tissue expanders were placed ( Fig. 36.3 ). After the expansion was complete, the expanders were removed at the time of revision TKA with hardware removal ( Figs. 36.4 and 36.5 ). Primary wound healing occurred without complications.
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The soft tissues about the knee are relatively unforgiving, and problems that occur with wound healing can quickly result in potentially disabling, long-term complications.
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A comprehensive understanding of the systemic, anatomic, and iatrogenic variables that may be associated with wound problems after knee arthroplasty will help identify patients at risk. Once they are identified, management can be optimized throughout the perioperative period.
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Important preoperative considerations include medical optimization, planning of appropriate skin incisions, and use of prophylactic soft tissue procedures such as tissue expanders or soft tissue flaps.
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Intraoperatively, knee arthroplasty that is performed efficiently with minimal soft tissue trauma in a technically rigorous manner will likely improve early wound healing.
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Postoperatively, if wound ischemia, hematoma, or drainage occurs, early immobilization followed by appropriate surgical intervention within the first week should be considered.
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It is critical to distinguish between primary wound problems that are not associated with deep periprosthetic infections and secondary wound problems that result from underlying deep infection. Therefore, early deep aspiration should be considered. In the presence of deep periprosthetic infection, the primary principle is appropriate treatment of the deep infection followed by salvage soft tissue procedures.
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In cases of primary wound complications, failure to aggressively address the problem places the patient at risk for development of secondary deep periprosthetic infection. Once infection occurs, the treatment strategy must change and is likely to be associated with worse results.
Introduction
In distinction to the hip, the soft tissue envelope about the knee can be unforgiving; furthermore, wound complications can rapidly and permanently compromise the success of any knee procedure. Whereas the general challenges posed by the temperamental nature of the periarticular soft tissues about the knee are understood, few concrete guidelines exist to minimize complications. Rather, only general principles can be outlined. These concepts are largely based on anecdotal evidence and case series rather than prospective, randomized trials.
Prior work has documented a large number of factors that may contribute to wound healing problems after surgery. These include systemic factors, local factors about the knee, and iatrogenic factors. Systemic factors associated with delayed wound healing include increased patient age, malnutrition, obesity, diabetes, immune system problems, smoking, medication effects, and peripheral vascular disease. Local factors include the presence of prior incisions, patella baja, and restricted range of motion (ROM). Iatrogenic factors include placement of the skin incision, how the soft tissues are handled during the operation, and how persistent wound drainage is managed postoperatively. In order to assess and manage as many variables as possible in an effective manner, it is important to develop a strategy that focuses on the three distinct time periods of an operation: preoperative, intraoperative, and postoperative.
Preoperative medical evaluation and optimization of underlying systemic conditions is critical. Tight control of diabetes, reversal of malnutrition, and smoking cessation are important for optimal wound healing. Evaluation of the soft tissues about the knee should also be performed by the operating surgeon. Presence of prior incisions, adherent or damaged skin, and evidence of peripheral vascular disease should be noted; if significant concerns exist, consultation with a plastic surgeon can help to determine whether soft tissue expanders or prophylactic soft tissue flaps are necessary. Furthermore, if pulses in the ipsilateral foot cannot be palpated, vascular surgery consultation should be considered to determine whether a revascularization procedure is required before knee surgery. The ROM of the knee should be determined, because a stiff knee can be associated with exposure difficulties and noncompliant periarticular soft tissues. Finally, radiographs should be examined to identify hardware requiring removal or significant patella baja that may require exposure steps beyond the standard surgical approach. Once all of the required assessments have been performed, the operating surgeon can consider each issue and formulate a plan regarding whether a prior incision will be used or a new incision made, whether prophylactic soft tissue procedures should be considered, and what type of additional exposure maneuvers may be required.
Intraoperatively, factors that may contribute to development of skin ischemia and increased wound problems include patient hypothermia, poor placement of the skin incision, failure to create full-thickness subcutaneous soft tissue flaps, use of a tourniquet, increased mechanical trauma to the skin and subcutaneous tissues, use of a lateral peripatellar release, and failure to use a deep drain. Without doubt, total knee arthroplasty (TKA) performed efficiently, with minimal soft tissue trauma and with attention to optimizing component positioning, has the best chance of facilitating uncomplicated wound healing.
Despite diligent preoperative assessment and optimization and prudent intraoperative handling of the soft tissues and care of the patient, wound problems still occur postoperatively in some patients. Skin ischemia and wound drainage are two early problems that should be identified rapidly and aggressively managed. Wound problems or hematoma significant enough to require reoperation have been reported to occur in about 0.5% of patients undergoing TKA ; in addition, persistent wound drainage occurs in 1% to 3% of cases. If either of these issues is present on postoperative day 2 or 3, early intervention may reduce the need for reoperation, although there are no data to directly support this assertion.
After TKA, skin oxygenation declines early in the postoperative period, improves beginning at about 48 hours, and recovers toward baseline by 10 to 14 days ; furthermore, tissue oxygenation has been directly correlated with the rate of collagen deposition. Therefore, marginal skin may benefit from any measure that minimizes this early decline in oxygenation until the rebound effect occurs. Although anemia was once thought to be an important factor in tissue oxygenation, it appears that the oxygen requirements to stimulate rapid wound healing are met by blood with a wide range of hemoglobin content; therefore, as long as perfusion and oxygenation of the blood are adequate, anemia does not seem to be a significant concern. Other factors can reduce tissue perfusion and oxygenation, including peripheral vascular disease, significant pulmonary disease, poor cardiac output, hypothermia, volume depletion, and peripheral vasoconstriction; each of these may adversely affect wound healing and should be optimized in the postoperative period.
Other studies indirectly support early intervention when wound healing is suboptimal. Skin oxygenation has been proved to decline with knee flexion, especially beyond 40 degrees ; therefore, in the presence of early skin ischemia, physical therapy and continuous passive motion, if used, should be stopped. In addition to promoting early wound healing, immobilization may also diminish postoperative wound drainage. However, significant drainage beyond 5 to 7 days postoperatively, especially if bloody, should be treated with early exploration, hematoma evacuation, and reclosure of any dehiscence of the arthrotomy that is identified. Early wound complications and the development of hematoma that requires reoperation have been shown to be associated with an increased risk of infection and the need for subsequent soft tissue procedures. However, it is not known whether this is caused by intervention that was initiated too late (i.e., after irreversible skin ischemia or bacterial seeding occurred). Importantly, one small study demonstrated that when wound drainage persists after TKA, early intervention to evacuate a hematoma, followed by reclosure, can be associated with successful outcomes.
When one is presented with suboptimal wound healing, drainage or hematoma, the prime directive is to intervene aggressively to avoid secondary deep periprosthetic infection. Therefore, although no absolute directives exist and nonsurgical care may be the optimal intervention in certain cases, when early wound breakdown occurs or drainage persists beyond the first 2 or 3 days, definitive surgical intervention should be considered within the first week after TKA.
Indications and Contraindications
In this section, five scenarios relating to soft tissue and wound management about the knee are reviewed; indications and contraindications for specific treatment strategies are outlined.
Multiple Prior Skin Incisions
The presence of prior incisions should be carefully evaluated. Transverse incisions about the knee can be crossed with a new vertical midline incision with relatively little concern. In distinction, any vertical midline incision should be reused if it is within about 3 cm of the midline. The incision may need to be extended proximally or distally to allow mobilization of the skin. Full-thickness flaps should be raised. In general, the medial and lateral flaps should be elevated only to the margins of the patella. If multiple vertical incisions are present, the lateral-most incision that will allow the standard medial parapatellar arthrotomy to be performed should be used; the medially based, full-thickness flap is then mobilized to the medial border of the patella. These medially based flaps are preferable to laterally based flaps because the arterial inflow is chiefly from the medial side.
Short oblique incisions can be incorporated into modified vertical incisions as long as they are close to the midline. Expert opinion suggests that if a new vertical incision is made in the presence of prior vertical scars that can not be adequately reused, it is prudent to avoid creating skin bridges smaller than 2.5 to 5 cm between the old and new incisions. In some cases, Doppler examination of the skin may be helpful to identify perforating vessels that can help guide optimal incision placement.
When multiple prior skin incisions are encountered in patients with other risk factors for wound healing, such as diabetes, peripheral vascular disease, or a history of wound problems after surgery, prophylactic soft tissue procedures should be considered. Of historical interest only, the sham incision was used selectively to identify those patients at risk for poor wound healing. The procedure involved making a provisional skin incision several weeks before the planned orthopedic procedure. If the wound failed to heal, soft tissue coverage could be planned before the TKA. The risks of deep periprosthetic infection were thought to be minimized with this strategy, because the prosthesis would not be exposed if wound problems developed. Alternatively, if the wound healed without complication, the knee procedure could subsequently be performed within a few weeks with low risk of soft tissue problems. Some of the value of the sham procedure may have derived from the hyperemia that occurs during wound healing. This enhanced arterial inflow may have stimulated early wound healing at the time of the TKA. Presently, patients in our practice who are perceived to be at high risk of delayed wound healing are referred to a plastic surgeon for consideration of either prophylactic tissue expanders or soft tissue transfers. The technique for use of tissue expanders is described in this section; prophylactic and salvage soft tissue transfers are reviewed Chapter 37 .
Prior Burns, Irradiation, or “Road Rash” Abrasions About the Knee
Patients with significant prior burns, irradiated skin, or old “road rash” abrasion injuries about the knee should be approached with caution. In many cases, especially with injuries occurring 30 or 40 years ago, the soft tissues were treated with healing by secondary intent or with skin grafting directly onto fascia. The poor quality of this skin, coupled with deficient or fibrotic subcutaneous tissue, poses significant challenges. In most cases, these patients are not candidates for soft tissue expansion, and the optimal strategy is to resect the affected skin and proceed with prophylactic soft tissue transfer.
Prior Soft Tissue Flaps
The presence of a prior soft tissue flap about the knee should prompt consultation with a plastic surgeon. In many cases, healthy, well-positioned flaps can be elevated without complication at the time of the knee procedure by the plastic surgeon. If the plastic surgeon who performed the original transfer is not available to assist with this process, it is important to obtain prior operative reports so that specific details, such as the location of the vascular pedicle, can be determined. This reduces the risk of damage to the vascular pedicle during elevation of the flap.
Poorly placed soft tissue flaps and flaps that were placed in salvage or emergent situations, especially those complicated by delayed healing and repeat débridement, may be of marginal quality. In these cases, revision soft tissue procedures may be required before the knee procedure. In many such cases, no local flap options exist, and free flaps must be considered. These techniques are described Chapter 37 .
Postoperative Wound Ischemia and Soft Tissue Necrosis
Small areas of marginal skin necrosis measuring a few millimeters in width and up to 2 to 4 cm in length may be managed with observation and local débridement of the eschar in a delayed fashion. However, the presence of superficial infection or persistent serous drainage from these areas should prompt surgical débridement. In some cases primary excision and closure is possible, but for extensive areas of involvement, especially with tight skin, a medial gastrocnemius muscle flap and skin grafting may be required. The goal is intervention before secondary deep periprosthetic infection occurs.
Postoperative Wound Drainage and Hematoma
Postoperative wound drainage and hematomas occur to some degree in every patient undergoing TKA. It is difficult to define absolute parameters requiring reoperation. In general, large hematomas that distend the skin and contribute to skin ischemia, severe pain, or wound drainage should be treated aggressively with evacuation and primary closure over a drain. After TKA, small areas of spotting less than 2 cm in diameter may be present for several days. However, significant serosanguineous drainage or frank bleeding from the wound beyond 48 hours is concerning for dehiscence of the arthrotomy. Immobilization and bed rest may be instituted for 24 to 48 hours, but if resolution of the drainage and resumption of ROM and mobilization with physical therapy are not rapidly accomplished, reoperation with débridement and reclosure of the arthrotomy over a drain should be considered. In a study of 11,785 total joint arthroplasties, 2.9% (300 cases) developed drainage beyond 48 hours postoperatively. In 217 cases, drainage stopped within 4 days with local measures such as wound care, with no sequelae. Of the remaining 83 patients, 63 (76%) were treated successfully with a single débridement. In general, surgical intervention for hematoma or wound drainage complications should be undertaken within 7 days after the TKA procedure.
Finally, in cases with apparent hematoma or persistent wound drainage, it is important to exclude deep infection. Therefore, in all cases, preoperative or intraoperative aspiration from the knee should be considered, away from any area of erythema or potential superficial infection. Although the interpretation of cell count data from joint fluid aspirate in the acute postoperative period is difficult, new guidelines are available that help to predict whether the drainage is secondary to a mechanical failure of the arthrotomy closure or possibly related to acute deep periprosthetic infection. In the acute postoperative period, the optimal cut-off values for infection were about 28,000 white blood cells (WBCs) per microliter and 89% polymorphonuclear cells. If there is evidence of acute deep periprosthetic infection, the decision must be made whether to perform débridement and polyethylene exchange or to proceed directly with two-stage revision. The results of traditional early débridement have been poor after total joint arthroplasty, but better outcomes have been reported with a two-stage débridement using antibiotic beads and prosthesis retention.
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