Longer follow-up must show whether boxcar volume and texture gains last past six months without late pigment change. The 2026 split-face trial found recovery events mild and short-lived, with pigment darkening in 8.3% resolving within one month.
Boxcar acne scars are broad depressed scars with sharp edges. Fractional microneedle radiofrequency uses tiny needles plus heat to trigger collagen, and PLLA is a collagen-stimulating material. According to Springer Dermatology and Therapy, the trial enrolled 24 Asian adults with moderate-to-severe atrophic scars, skin types III-V, giving two monthly sessions with PLLA on one side and sterile water on the other the 2026 trial report.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- How was recovery after each session?
- What does pigment risk mean for medium to darker skin?
- Why track boxcar scars separately?
- What must longer follow-up prove?
How was recovery after each session?
Mild redness affected 4.2% of participants and faded within one month after the first treatment and within three weeks after the second. Acne flare also affected 4.2% after each session and cleared on its own within five days after the first treatment and within three weeks after the second. No extra procedure was needed for either event.
SpringerMedizin summarizes this short recovery pattern as mild, transient and self-limiting the treatment safety summary. That means most people did not have prolonged downtime in this small group. It does not promise the same course for every skin type or clinic protocol.
- Ask how redness is checked at week 1 and week 3
- Ask what acne flare plan is used without antibiotics or steroids
- Ask when to call sooner for blistering, severe pain, or spreading dark spots
What does pigment risk mean for medium to darker skin?
Mild post-inflammatory hyperpigmentation occurred in two participants and cleared within one month. That shows pigment risk exists in skin types III-V but was brief in this trial. Darker skin still needs careful sun protection and early pigment checks after energy treatment.
A wider systematic review of radiofrequency microneedling in Fitzpatrick III-VI found temporary darkening in 7 of 35 studies, plus one mild prolonged case and one permanent scar. The trial result therefore fits a broader pattern where short darkening is more common than lasting harm. People with a history of long dark marks should discuss test spots and treatment energy.
Why track boxcar scars separately?
Boxcar scars often respond differently from narrow icepick scars. The CO2-plus-PLLA analysis published in Clin Cosmet Investig Dermatol found significantly greater improvement for rolling and boxcar scars than for icepick scars the CO2-plus-PLLA scar-type analysis. Separate boxcar volume and texture scores prevent icepick results from hiding boxcar change.
At six months, PLLA-treated sides showed significant texture and scar-volume improvement versus baseline and versus control sides. More patients reported greater than 75% improvement on the PLLA side. For boxcar concerns, ask for side-by-side photos and volume numbers for boxcar areas alone.
What must longer follow-up prove?
The trial authors state larger multicenter trials with longer follow-up are needed to confirm results and refine settings. A short six-month window cannot show late relapse, delayed pigment shift, or lasting collagen change.
Boxcar depth, edge sharpness, and makeup-free texture need repeat measures past one year. Ask your clinic how they photograph and measure boxcar volume at 12 months.
- Durability of boxcar volume gain at 12 months or later
- Late pigment change by skin type and scar location
- Scar-type results reported separately for boxcar, rolling, and icepick
- Treatment settings linked to tissue change, not only surface photos
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