When surgeon scoring was analyzed separately, SBSES and MSS scores were similar between treatment and control groups, with 1 exception: 2-week MSS scores were better for the treatment group according to surgeon A (P = .026). When grades were averaged, SBSES scores were again similar at all time points (Figure 4A); MSS scores were better for the treatment group at 2 weeks (P = .036) and equivalent at all other time points (Figure 4B). For the SBSES, Spearman correlation coefficient ρ with 95% confidence interval (CI) was 0.37
(95% CI, 0.08-0.66) at 2 weeks, 0.48 (95% CI, 0.20-0.76) at 6 weeks, and 0.62 (95% CI, 0.33-0.91) at 12 weeks. Following the same pattern for the MSS, ρ was 0.20 (95% CI, –0.09 to 0.49), 0.51 (95% CI, 0.23-0.79), and 0.32 (95% CI, 0.03-0.61).
Independent multivariate analysis revealed that age over 65 years was a significant predictor of worse scores. On SBSES, the odds ratio (OR) was 1.15 (95% CI, 1.07-1.24) for surgeon A and 1.11 (95% CI, 1.05-1.18) for surgeon B. On MSS, the OR was 0.89 (95% CI, 0.84-0.94) for surgeon A and 0.95 (95% CI, 0.91-0.99) for surgeon B. The likelihood of having worse SBSES scores according to surgeon A was 4.72 times higher if the pre-albumin level was under 20 mg/L (95% CI, 1.15-19.36). Albumin level under 3.5 g/dL and absolute lymphocyte count under 1500 cells/µL were not found to be independent predictors of poorer scores.
Patients’ overall opinion (P = .63) and assessment of their scars relative to expectations (P = .25) on the Likert scales were not different between groups. More scars exceeded patients’ expectations and had more excellent ratings in the control group. The 2 groups were similar with regard to relative importance of various patient-related outcomes. Factors most important to overall outcome were relief of hip pain, followed by implant longevity and length of recovery. Least important were incision-related variables.
There were only 3 minor noninfectious wound complications (6%), 2 in the treatment group and 1 in the control group. In the treatment group, a 67-year-old man with diabetes (ASA class III; BMI, 32.1 kg/m2; received transfusion) had 2 small areas (<5 mm) of superficial ulceration at 6-week follow-up—one at the proximal aspect of the incision and the other near the midpoint along the flexion crease. Both lesions resolved by 12-week follow-up. Also in the treatment group, a 77-year-old woman (ASA class II; BMI, 24.9 kg/m2; received transfusion) at 6 weeks had a spitting suture, which was removed in clinic without further issue. In the control group, a 55-year-old woman (ASA class II; BMI, 27.4 kg/m2) had a suture reaction near the proximal aspect of her incision 3 weeks after surgery. This reaction, which presented as a mild, localized erythema without pain, tenderness, or drainage, resolved by 6-week follow-up. None of these wound complications required intervention beyond observation.
Discussion
This study was designed to provide a bipartisan measure of wound-healing cosmesis after DA-THA. Scar evaluation by blinded plastic surgeons served as a standardized, clinical assessment, whereas the patient questionnaire offered a more subjective appraisal. The modified MMS25 and the SBSES24 are the only 2 wound-grading systems designed and validated for photographic assessment of postsurgical scars. Most scar evaluation schemes pertain to burn or traumatic scars.26,27,31 As a result, many earlier studies intending to compare incisional scars used poorly suited evaluation systems.
The current literature includes reports on 3 studies with scoring-based scar assessment in THA; all used grading systems designed for either burns or traumatic wounds, but 2 also used a VAS.32-34 VASs have been validated for measuring wound cosmesis but are entirely subjective and without structure and provide no feedback as to why a scar was rated good or bad.24 Mow and colleagues32 prospectively compared scars after standard posterior or MIS approaches and found no differences according to a scoring system intended for burn scars. In our study population, we found no group differences in patients’ cosmesis of their scars.
Although scars can take a year or longer to fully mature, researchers from the University of Michigan discovered that scar appearance at 1 year correlates highly with cosmesis 12 weeks after closure, though poorly with cosmesis 10 days after closure.35 Therefore, any observed differences in scar cosmesis between groups at 12-week follow-up would likely persist, whereas differences at 2-week follow-up would have little bearing on ultimate appearance. For this reason, our primary outcome measure was healing process and cosmesis at 12 weeks. High wound complication rates have been reported for MIS-DA-THA.8,14-16 Jewett and Collis15 noted a 4.6% wound complication rate (3% noninfectious ulcerative dehiscence, 1.6% superficial infection), which is comparable to the 6% rate found in this study. However, there likely is some variability across studies in what constitutes a wound complication or superficial infection. Of our 3 wound complications—stitch reaction, spitting suture, small noninfectious ulceration—only the ulceration was of a severity similar to that reported by Jewett and Collis.15 Matta and colleagues8 reported only 3 wound complications (in 494 patients), all severe enough to require operative intervention. One explanation for this low complication rate is use of a ring retractor, as it is routinely depicted in their technique paper. However, no specific reference is made to gauge how often the device was used.