Orthopedics

Materials and Methods

After receiving Institutional Review Board approval, the records of patients who underwent surgery by a single fellowship-trained adult reconstruction surgeon (L.P.) at a single institution between July 1, 2009, and June 30, 2010, were identified. All cases other than joint reconstruction cases were excluded, leaving 315 consecutive cases. Of these, 37 cases were revision surgeries and were excluded. Ultimately, a retrospective review of 278 consecutive primary joint reconstruction cases was conducted. No cases were excluded based on preoperative diagnosis, patient demographics, or patient age. Preoperative history and physical records were evaluated for comorbidities (eg, diabetes mellitus), medications (eg, steroids), smoking status, and body mass index. Operative reports dictated by the attending surgeon provided information on the surgical procedure, use of a drain, wound closure technique, type of suture/staple used for skin closure, and intraoperative wound complications. Postoperative hospital progress notes and clinic follow-up notes were reviewed to identify indicators of postoperative complications (eg, wound characteristics, persistent drainage, antibiotic usage, clinic procedures, and revision surgery) within 30 days of the index surgery.

The study group comprised 106 men and 161 women. Average patient age at surgery was 63 years (range, 18–92 years), and average body mass index of the cohort was 33.7 kg/m² (range, 25–51 kg/m²).

Surgical Technique

Overall, 153 procedures were at the knee (including total knee arthroplasty, unicompartmental arthroplasty, and patellofemoral arthroplasty), and 125 procedures were at the hip (including total hip arthroplasty and hemiarthroplasty) (Table 1). All knee procedures involved a less-invasive midline incision (average, 4–6 inches) with a medial parapatellar arthrotomy and included placement of a hemovac suction drain that exited the skin at a remote site and was removed at bedside on postoperative day 1. All knee procedures, except patellofemoral arthroplasty, were performed with computer-assisted navigation, and all trackers were placed within the primary surgery wound. All hip procedures involved a less-invasive posterolateral approach with a skin incision that averaged 4 to 6 inches depending on the patient size and difficulty of the procedure. Hip procedures were performed without navigation or placement of drains.

Table 1: Primary Joint Reconstruction Cases

Wound closure was completed simultaneously by the surgeon (L.P.) and his chief resident. In hips, the capsule and external rotators were repaired to the greater trochanter, followed by a closure of the fascia with interrupted figure-of-eight 1-0 Vicryl suture (Ethicon, Inc, Somerville, New Jersey). The subcutaneous tissue was closed with 2-0 simple interrupted Vicryl stitches. The knee fascia and subcutaneous tissue were closed in a similar sequential manner, with the knee in 30° of flexion (including skin). Skin was consecutively closed with a staple gun with metal staples for the first 7 months of the study period, for a total of 160 cases. Surgeon preference changed to a subcuticular closure in February 2010, and 51 consecutive cases were closed with a 3-0 monofilament Biosyn absorbable suture (Covidien). The surgeon subsequently switched to the 3-0 V-Loc subcuticular stitch for 46 consecutive cases. Staples served as the original preferred method of skin closure. The surgeon applied subcuticular suture closure for consecutive cases (first Biosyn, then V-Loc) until increased concern for wound complications led the surgeon to revert to staple skin closure for the final 21 cases.

The Biosyn and V-Loc sutures are composed of glycolide, dioxanone, and trimethylene carbonate to form an absorbable compound. Average duration until absorption is 90 days. The V-Loc contains unidirectional barbs that project from the longitudinal axis of the suture. The surgical skin stapler (Covidien) held stainless steel staples.

The wounds closed with a subcuticular suture then had Mastisol (Eloquest Healthcare, Ferndale, Michigan) and adhesive skin closure strips applied superficially. The staples group had no adhesive skin closure strips. All wounds were then dressed with sterile Xeroform dressing (Covidien), gauze, ABD pads, and cast padding.

Original operating room dressings were changed on postoperative day 2. Drains were removed on postoperative day 1 in patients undergoing total hip arthroplasty. The surgeon’s standard anticoagulation protocol included nightly warfarin starting the day of surgery, with a goal of reaching a therapeutic international normalized ratio of 2.0 to 3.0 for 4 weeks. The dosage of warfarin was managed by pharmacists in the anticoagulation dosing service at the hospital. Patients undergoing total knee arthroplasty, but not those undergoing total hip arthroplasty, received prophylactic dose low-molecular-weight heparin on postoperative day 1 as a bridge until international normalized ratio levels were therapeutic.

Patients returned to the clinic approximately 2 weeks postoperatively for routine clinical follow-up, including wound inspection. Subsequent outpatient follow-up consisting of clinical and radiographic evaluation occurred at 4 and 8 weeks postoperatively.

Results were analyzed by Pearson’s chi-square test for equality of 2 independent proportions to determine whether the incidence of complications had achieved a statistically significant difference. For all analyses, a statistical confidence level of 95% was used. Post-hoc analysis indicated that our study population provided sufficient power to delineate, with significance at the α=0.05 level, differential complication rates of >6% for staple vs suture contrasts, >7% for staple vs V-Loc contrasts, >6% for staple vs Biosyn contrasts, and >14% for Biosyn vs V-Loc contrasts. The Wilson/Ghosh method was used to formulate 2-sided confidence intervals for complication rates, which accounts for the statistical complication inherent in generating confidence intervals for small binomial distributions. Data analysis was conducted using SPSS version 19.0 software (SPSS, Inc, Chicago, Illinois) and the R software platform (R Foundation for Statistical Computing, Vienna, Austria).

Results

In the review of 278 consecutive cases of primary joint reconstruction, 17 postoperative wound complications occurred, including cellulitis, stitch abscesses, wound dehiscence, and deeper infections requiring irrigation and debridement (Table 2). Seven (3.9%) wound complications occurred in 181 cases closed with staples. Ten (10.3%) wound complications occurred in 94 cases closed via subcuticular absorbable suture: 4 (7.8%) in 51 cases closed via subcuticular Biosyn suture and 6 (13.0%) in 46 cases closed with V-Loc suture. Thus, a higher complication rate occurred in the suture group compared with the staple group (P=.033). Furthermore, a difference in complication rate existed between the staple group and the V-Loc suture group (P=.017). Although a trend existed toward decreased incidence of complications in staples compared with Biosyn, statistical significance was not achieved (P=.24). Similarly, no statistical significance was found when comparing Biosyn suture with V-Loc suture (P=.40).

Table 2: Complications Based on Closure Technique

Five (29.4%) of the 17 complications occurred in patients who were active smokers; 3 were closed with staples and 2 with subcuticular Biosyn closure. Average body mass index of the patients who experienced complications was 32.9 kg/m² (range, 26–42 kg/m²); the average of the entire cohort was 33.7 kg/m².

When classifying wound complications as minor or major, where major complications required surgical intervention, 6 complications were major. Two (1.1%) major wound complications occurred in 181 skin closures completed with staples, and 4 (4.2%) major wound complications occurred in 96 cases closed via subcuticular absorbable suture. Of those 4 complications, 2 (4.3%) occurred in cases closed with V-Loc suture. Half (3/6) of all major complications occurred in active smokers. Average body mass index of patients who experienced major complications was 35.2 kg/m² (range, 29–42 kg/m²); the average of the entire cohort was 33.7 kg/m².

In comparing both major and minor complications with only major complications, both groups showed a higher incidence of wound complications with subcuticular absorbable suture skin closure compared with skin closed with metal staples. More complications occurred in the V-Loc group compared with the Biosyn group; however, given the small proportions involved, statistical significance was not achieved. To demonstrate these trends, the confidence intervals are displayed in Table 3. For the confidence intervals, the relevant interval used is 90% because comparing 2 proportions (the lower bound of one to the upper bound of another) is a 1-sided test for equality of the 2 proportions at the 95% confidence level.

Table 3: Confidence Intervals of Major Complications by Closure Technique

When looking at all complications by joint (ie, hip vs knee), a higher trend of complications existed in knees compared with hips for all methods of skin closure (Table 4). Regardless of joint, the complication rate was highest for V-Loc suture, followed by Biosyn suture and, lastly, staples. Again, given the small proportions, statistical significance was not achieved.

Table 4: Wound Complications Categorized by Sex and Joint

Discussion

The purpose of this study was to report our experience with the V-Loc barbed suture for skin closure in joint reconstruction, as well as overall subcuticular suture skin closure compared with that of metal staples. Changes in skin closure technique are secondary to multiple factors, including surgeon preference, patient marketability, hospital standards, and wound tension. Theoretical advantages of a barbed suture include distribution of tension throughout the wound, decreased knot-related complications, and faster application.^5–8

A randomized equivalency study of 188 patients evaluated bidirectional barbed suture vs conventional polydioxanone suture for dermal closure of Pfannenstiel incisions in gynecologic cases and reported similar cosmesis, infection, and dehiscence scores and comparable pain scores and closure time.⁵ Reports of decreased adverse events associated with the use of barbed suture are based on studies performed in minimally invasive facelift surgery.^9,10 An explanation for this difference in outcomes may be secondary to the relationship of the barb stiffness and direction with the native soft tissue.^11,12 The current study’s results in orthopedic joint reconstruction demonstrate similar incidences of major wound complications in the conventional subcuticular suture and V-Loc suture groups. However, an increased rate of minor complications occurred with the V-Loc suture. Potentially, the tightness and water-tight seal provided by the V-Loc suture is less forgiving than a conventional suture to the high stresses of postoperative mobilization and normal physiologic drainage after joint replacement. Given the same material composition of V-Loc and Biosyn sutures (glycolide, dioxanone, and trimethylene carbonate), the difference in complications is unlikely to be attributable to a biologic response. Moreover, the authors are unaware of any studies comparing biological and histological soft tissue responses to stainless steel staples with those to absorbable suture in skin closure.

The current study found a statistically significant higher rate of complications in the V-Loc group compared with the staple group. Whether staples or sutures lead to lower rates of wound inflammation is controversial, perhaps dependent on the location of the wound on the body.^2,13–16 Graham et al¹⁷ reported that staple closure resulted in better blood perfusion to wound sites compared with suture closure. Increased blood perfusion and decreased disruption of the wound site could enhance healing. Further investigation is needed on soft tissue disruption in V-Loc sutures, particularly compared with skin staples.

Although the V-Loc suture represents a relatively recent advance and subject of research, multiple studies have evaluated suture vs staple closure in joint arthroplasty.^1,2,18 However, debate exists on which is the optimal method of closure. Khan et al² investigated skin closure in joint arthroplasty and reported that skin staples were superior to subcuticular suture. They concluded that staple closure was faster than suture closure, with no difference in complication rate, patient satisfaction, or cosmesis.² A recent meta-analysis by Smith et al¹ reported that staples were associated with a higher rate of infection in hip surgery compared with suture closure. The meta-analysis included all orthopedic procedures of the hip and knee and did not differentiate between superficial and deep infections—intrinsic limitations to that type of study.¹ The current study’s results showed decreased rates of major and minor complications in the staple group compared with the subcuticular suture group.

The overall complication rate in the current study was higher in knees than in hips, but given the small proportions, no statistical significance was achieved. Khan et al² attributed this to the fact that incisions at the knee are longer than those at the hip and that the skin at the knee is more mobile than that at the hip. They reported no statistically significant difference in their late complication rate (hip, 14.7%; knee, 18.8%).²

The current study did not measure cosmetic outcomes, pain scores, or closure time. Furthermore, although cost can be a driving force for many surgeons and institutions, the authors did not include that in their analysis. The literature reports that metal staples are more expensive than conventional suture; however, the authors of the current study we found no comparison with V-Loc suture.^1,2,19 Although a consecutive series, the current study faces the intrinsic limitations of a retrospective analysis, including data collection limited to medical records. Also, not all factors related to wound healing could be accounted for, including nutrition, amount of drainage, and hygiene. However, the authors of the current study analyzed 2 known risk factors for wound complications, particularly in orthopedic surgery: obesity and smoking.^20–22 Patients with these risk factors deserve special attention with regard to wound closure and may benefit from a skin closure associated with fewer surgical-site complications.

Another limitation of the current study is the power. A significantly larger number of patients made up the staple cohort than the conventional suture and V-Loc suture cohorts. However, the limited number of skin closures by subcuticular means was secondary to the surgeon’s heightened concern for wound complications. Although subcuticular suture closure may require more technical skill than staple placement, the authors do not believe a learning curve would occur, given the seniority and experience of the surgeon. Lastly, all complications in this study may not be directly attributed to skin closure method, indicating the need for further randomized, prospective trials.

The incidence of wound complications in surgical joint reconstruction ranges from 0.33% to 50%, with the mode deviating toward the lesser number.^23–25 The complication rate in the current study varied depending on the type of skin closure used. Early surgical intervention for total knee arthroplasty wound healing has been associated with further complications, including deep infections, resection arthroplasty, and flap coverage.²⁶ Wound complications in patients undergoing joint reconstruction can cause myriad problems and should be minimized by all means available.

Conclusion

Aesthetics and efficiency often are the driving forces of innovation. Based on the authors’ clinical experience, wound and infectious complications should be considered when choosing a method of skin closure in joint reconstruction procedures.