The results of the present study would support out hypothesis that operative technique would affect wound healing in primary TKA. Specifically, patella eversion and anterior translation of the tibia were related to low score of the wound healing. TKA without patella eversion and anterior translation of the tibia is well known as the minimally invasive technique. Proponents of the minimally invasive technique claim that these techniques will result in an earlier recovery of range of motion, an earlier discharge from the hospital, and less pain compared with the conventional TKA without any complications including the wound problems [13]. Dalury et al. indicated that patellar eversion and anterior tibial translation could have no adverse effects on the range of motion, quadriceps strength, or patient’s knee preference during the early postoperative recovery period after TKA [14]. However, their study did not investigate the wound healing problem.
In the present investigation, inclusion criteria were strictly established and postoperative rehabilitation was done using the same protocol at our institution. Therefore, only surgical factors could be assessed and discussed. Several surgical factors affecting the wound healing after TKA has been reported so far. For example, surgical factors include the location of the incision, longer tourniquet use, and poor soft tissue handling. Previous studies indicated that medial parapatellar skin incision provided the worse outcome of the wound healing than anterior midline skin incision [10]. Nevertheless, in the more recent study, wound healing of these two incisions were reported to be similar [15]. In the current study, for that reason, medial parapatellar skin incision was used. Concerning the tourniquet time, Olivecrona et al. reported that tourniquet time over 100 min was associated with an increased risk of complications after TKA (OR 2.2, CI 1.5–3.1) [11]. In our study, all procedures were done by the same surgeon and using a tourniquet for an average of 73 min, which seemed not to influence on the wound evaluation score. As to the soft tissue handling, previous reports suggested that the distal part of the skin incision was significantly more hypoxic than the proximal part in TKA [16, 17]. Therefore, atraumatic wound edge retraction should be carried out especially in the distal part. However, except for this technique, gentle handling of the soft tissue has not been investigated in detail. Reification of the technique has not been made in the handling methods. Detailed surgical technique affecting the wound healing was thus still unknown. From the present study, intraoperative patella eversion and anterior translation of the tibia during the cutting phase in knee flexion would lead to wound hypoxia of the edge, and thus, those should be avoided for wound healing in primary TKA.
Recently, barbed suture has been used for closure of TKA [18–22]. Actually, safety and efficacy of barbed suture have been reported in several studies. However, especially in TKA, previous studies indicated that the use of the barbed suture would lead to higher complication rate especially in wound healing compared with conventional staples [4, 23]. Potentially, the tightness and water-tight seal provided by the barbed suture are less forgiving than those by a conventional suture to the high stresses of postoperative mobilization and normal physiologic drainage after TKA [4]. On the other hand, it is possible that barbed suture may lead to quality cosmesis and better wound score in some cases [23]. As to the HWES, average value was similar to the recent study using the barbed suture [24]. Fortunately, major wound problems did not occur in the present study, although unidirectional barbed suture was used in all cases. Contrary to previous reports, patients with uncontrolled diabetes mellitus, smoker, obesity, and any severe comorbidity were excluded, and wound drainage was performed for 2 days postoperatively to decrease knee effusion. Moreover, wound condition was carefully assessed for 2-week admission in the present study. Presumably, for that reason, major wound healing problems did not occur.
Several limitations should be noted in the present study. First, the weakness of the present study was that this was not performed as a prospective randomized trial study. Second, the current study was done and assessed by a single surgeon at our institution. Thus, our study may not be representative of the results obtained by other surgeons in other countries. Third, serum albumin level was assessed preoperatively, though wound healing could be affected by postoperative nutrition condition. Fourth, the use of one design was optimal for the material. Actually, surgical techniques were different between the two designs because the component design of the tibia, especially in length of the keel, is different between these designs. Lastly, as the healing of the surgical wound was basically acceptable regardless of wound score in the present study, it was less meaningful except for those who would like to obtain quality cosmesis of the surgical wound in TKA. However, as the current study was the first to examine the important surgical factors affecting wound score after primary TKA, our results offer useful information that patella eversion and anterior translation of the tibia were related to low score of the wound healing following TKA.