Original Research

Evaluation of Wound Healing After Direct Anterior Total Hip Arthroplasty With Use of a Novel Retraction Device

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Use of shorter incisions in minimally invasive surgery total hip arthroplasty (THA) may come at the cost of poorer cosmesis, possibly a result of the excessive retraction needed for visualization. This may be particularly relevant in the direct anterior approach, in which wound-healing issues are common.

We prospectively investigated whether a specialized ring retractor was effective in minimizing wound-edge trauma, as evidenced by improved scar cosmesis. Fifty patients having direct anterior THA were randomized to surgery with or without ring retractor. Incisional photographs 2, 6, and 12 weeks after surgery were graded by 2 blinded plastic surgeons.

Wound scores and patient satisfaction with scar appearance were similar between groups. Our results suggest no improvement in wound cosmesis with use of this retraction device.



It is thought that, by placing more emphasis on soft-tissue preservation, minimally invasive surgery total hip arthroplasty (MIS-THA) results in less soft-tissue trauma, less blood loss, and earlier recovery.1-3 Despite these improvements over standard methods, there is a concern that the vigorous retraction needed for proper visualization through smaller incisions could injure soft tissues.4-7 Single-incision direct anterior THA (DA-THA) has gained in popularity because of the true intermuscular/internervous plane through which the procedure can be performed with relatively minimal muscle dissection using MIS techniques.8,9 This approach may offer quicker recovery and superior stability in comparison with nonintermuscular methods, which unavoidably cause more muscle damage.10-12

Although the evidence of these early gains is encouraging, several studies have found high complication rates with DA-THA.8,13-17 Noted disadvantages include a steep learning curve, lateral femoral cutaneous neurapraxia, need for a specialized table, and higher fracture and wound complication rates. Not surprisingly, with increased surgeon experience, the complication rate decreased substantially.14,15 However, wound-related complications remained steady, with 2 recent large studies reporting rates of 4.6% and 2.1%.14,15 The thin anterior skin, high tensional forces along the groin crease and perpendicular to the typical DA incision, and less resilient soft-tissue envelope are postulated reasons for wound-related issues, which are likely magnified in patients who are more obese.15,16

A novel device designed to lessen tissue damage is the ring retractor (Figure 1). Used initially in general surgery and obstetrics, it consists of 2 semirigid polymer rings connected by a flexible cylindrical polymer membrane.18-20 The lower ring is tucked and anchored underneath the wound edge, and then the upper ring is rolled down and cinched onto the skin. The resultant tension on the polymer sleeve—imparted by the rigidity of the ring—provides strong, evenly distributed wound-edge retraction. It also provides a physical barrier between the wound edge and the rest of the operative field. Proponents of the ring retractor claim increased wound-edge moisture, less bruising, and reduced local trauma compared with standard metal retractors alone.

Wound-edge retractor forces are doubled during MIS-THA compared with conventional THA.14-20 This may explain reports of worse scar cosmesis with MIS-THA. Given the theoretical benefits of minimized wound-edge trauma, the ring retractor may improve scar appearance compared with standard retraction alone. Any clinically relevant effect on cosmesis should be readily apparent to justify use of the retractor in this regard. Although some surgeons routinely use the device for primary THA, it has not been the subject of any recent orthopedic studies.

In the present study, we prospectively investigated wound cosmesis with and without use of the ring retractor in patients undergoing DA-THA.

Materials and Methods

This prospective, single-center, randomized study was reviewed and approved by the institutional review board at our facility. Consent was obtained from all participating patients.

We evaluated 50 surgical incisions in 48 patients. Eligible participants were over age 18 years and undergoing primary DA-THA. Exclusion criteria included previous surgery on the affected hip, a pathological hip condition requiring an extensile exposure, systemic inflammatory illness, chronic corticosteroid use, and dermatologic abnormality of the incisional area. One patient was having simultaneous bilateral THAs, and another was having staged bilateral THAs. Each hip in these patients was given its own case number and treated separately. Of the 49 patients who met all the inclusion criteria, only 1 decided not to participate (Figure 2).

Stratified randomization with permuted block size (sex, body mass index [BMI]) was used to assign patients in a 1:1 ratio to either the treatment group or the control group. In the treatment group, the Protractor Incision Protector and Retractor (Gyrus ACMI, Southborough, Massachusetts) was used with standard metal retractors. In the control group, only standard metal retractors were used. Patients were blinded to their group assignments, and surgeons were informed about each assignment only after the initial incision was made.

Clinical research investigators were blinded to the groups’ prospectively collected data. Collection time points were preoperative clinical visit, day of surgery through discharge, and 2-, 6-, and 12-week postoperative follow-ups. Day-of-surgery data included estimated intraoperative blood loss, operative side, operative time, intraoperative complications, and American Society of Anesthesiologists (ASA) physical status classification. Total length of stay, pain scores (range, 0-10), estimated drain output, and blood-transfusion data were also recorded. To evaluate whether the device had any effect on short-term functional outcome, we collected Harris Hip Scores (HHS) and Short Form–12 (SF-12, Version 2) scores at the preoperative and 6-week postoperative visits. We also documented any wound-healing-related issues or complications that occurred up until the final visit.


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