Analysis of vascular anatomy about the knee suggests that the choice of a midline skin incision is less disruptive to the arterial network. Medial peripatellar skin incisions are undesirable because they create a large, laterally based skin flap, which has been associated with higher wound complication rates secondary to lower oxygen tension to the lateral skin region [38, 39]. Placement of the skin incision slightly lateral to the midline may assist in eversion or lateral subluxation of the patella , particularly in obese patients in whom a large and bulky lateral skin flap resists patellar subluxation or eversion.

When previous skin incisions are encountered, selection of the most appropriate incision may diminish the risk-associated skin healing complications. It is usually safe to ignore previous short medial or lateral peripatellar incisions. One should be wary of wide scars with thin or absent subcutaneous tissues, as damage to the underlying dermal plexus is likely, increasing the risk of wound necrosis. Problems with placement of a longitudinal incision crossing a transverse incision previously used for high tibial osteotomy or patellectomy are uncommon [40].

If long parallel skin incisions exist, choice of the lateral most skin incision is favorable to avoid a large lateral skin flap that has previously been compromised. In complex situations, such as knees with multiple incisions or previously burned or irradiated skin, plastic surgical consultation is wise, both for the configuration of the preferred skin incision and for consideration of preoperative muscle flap procedures if the risk of skin necrosis is substantial. In selected complex situations, using a staged technique can reduce wound complications. A pre-revision skin incision to the depth of the subcutaneous fascial layer is made and then closed. If this incision heals without difficulty, one can later proceed with TKA with much greater confidence. This does not take into account the substantial dissection that occurs with a TKA, and caution is still warranted, with careful intraoperative and postoperative management of the soft tissues.

Soft tissue expansion techniques have been used successfully in cases of contracted soft tissues from previous skin incisions, burns, or irradiation [41–46]. Success has also been described for tissue expansion before primary TKA, conversion of arthrodesis, reimplantation following infection, and revision TKA [41–50]. These techniques involve implantation, usually subcutaneously, of an expandable reservoir, into which saline can be intermittently injected to expand the surface area of the skin. Studies have shown that while epidermal thickness is maintained, dermal thinning occurs, and overall dermal collagen synthesis is increased. Complications with soft tissue expansion have been minimal and include hematoma formation, reservoir deflation, infection, and skin necrosis from vigorous tissue expansion [50]. Disadvantages of soft tissue expansion include the requirement for additional surgical procedures and the time required for expansion.

Another complicating factor in choosing a skin incision follows previous muscle flap procedures. Knowledge of the prior surgical procedures is imperative before proceeding with surgical intervention. Care must be exercised not to disrupt the vascular pedicle of the flap or portions of the muscular flap itself. Again , consultation with a plastic surgeon is recommended.

A thorough preoperative vascular examination of the limb is necessary to minimize the risk of wound healing complications . The skin incision for TKA should be of adequate length to avoid excessive tension on the wound edges, particularly when the knee is positioned in extremes of flexion. Meticulous handling of the soft tissues is essential, and gentle retraction of the skin edges is necessary to avoid disruption of perforating arterioles originating in the subcutaneous fascial layer. It is best not to undermine large areas of the skin. If undermining skin flaps is required, it must be done in the subfascial plane to preserve the blood supply to the skin, which originates in the dermal plexus. Numerous studies have demonstrated that a lateral retinacular release decreases lateral skin oxygenation and increases the subsequent risk of wound complications [51–54]. If a lateral retinacular release is required, attempts should be made to preserve the lateral superior geniculate artery. Meticulous wound hemostasis is paramount to avoid postoperative hematoma formation. In the authors’ experience, performance of TKA without use of a tourniquet (except for cementation) is beneficial to reduce the incidence of hematoma formation as hemostasis is continuously obtained during the operative procedure in contrast to cases in which delayed vasodilation occurs after tourniquet deflation and wound closure has been completed. We favor routine use of suction drainage to reduce pain, postoperative hematoma formation, and facilitate early knee flexion. Wound closure without tension is imperative in minimizing the risk of skin necrosis. Additionally, recent studies evaluating the clinical and scientific efficacy of negative pressure wound therapy (NPWT ) suggest it may be helpful over closed surgical incisions [55–58]. Potential benefits include decreasing postoperative edema, regaining wound breaking strength more rapidly, and hematoma and seroma reduction [55–57].

Various types of wound complications can occur, including prolonged postoperative drainage, superficial soft tissue necrosis, and full-thickness soft tissue necrosis, in which the prosthetic components are usually exposed. All three types of wound problems require immediate attention, as delay in treatment risks deep infection and subsequent failure of the TKA.

Wound problems are a dreaded complication following TKA, and all measures should be taken to avoid them. Preventative measures include modification of patient risk factors, proper choice of the skin incision, gentle handling of the soft tissues, meticulous hemostasis, and wound closure without excessive tension. Should persistent wound drainage or soft tissue necrosis occur, early intervention is imperative, because delay risks deep infection and ultimate failure of the TKA. Cases associated with full-thickness soft tissue necrosis often require transfer of well-vascularized tissue, such as a medial gastrocnemius myocutaneous flap reconstruction.