The Battle of Biostimulators: PLLA vs hyperdilute CaHA

In her informative session “The Battle of Biostimulators: PLLA vs. Hyperdilute CaHA,” Kay Durairaj, MD, FACS, offered an engaging, comprehensive comparison of two widely used biostimulatory injectables: Poly-L-Lactic Acid (PLLA; eg, Sculptra) and hyperdilute Calcium Hydroxyapatite (CaHA; eg, Radiesse). Both agents have emerged as powerful tools for nonsurgical facial and body rejuvenation, stimulating collagen and elastin to restore volume, improve elasticity, and enhance skin quality. 

Dr. Durairaj stressed that biostimulators can be used with surgical facelifts. Rather than being contraindicated, as has been suggested in some mainstream media, their presence may improve outcomes by contributing to firmer, thicker, and more youthful skin through ongoing collagen production. Following are key takeaways from the session.

COLLAGEN AND ELASTIN BIOLOGY

Collagen and elastin are long-lived proteins with half-lives of 15 years (Collagen I) and 95 years (Collagen III). Aging leads to thinning of the dermal layers, disorganization of collagen bundles, degradation of glycosaminoglycans (GAGs), and fragmentation of elastin fibers, like a bathing suit losing its stretch. This cumulative damage shows the value of repeated collagen-stimulating interventions, including biostimulators, peels, microneedling, and retinoids. 

HYPERDILUTE CaHA (RADIESSE)

CaHA consists of 30% synthetic microspheres suspended in 70% aqueous gel, providing an effective scaffold for fibroblast activation. When hyperdiluted, CaHA reduces the risk of vascular occlusion and nodule formation and can be safely used on the face and body. Recommended protocols vary by treatment area. For example: 

• Abdomen: 1:3 dilution to improve elasticity.
• Neck: 1:2 to 1:6.
• Knees, elbows, and arms: 1:2 using one syringe per side.
• Buttocks and thighs: 1:1 to 1:4, depending on laxity.

Clinical results show increased Collagen III at 4 to 9 months and Collagen I by 9 months, along with elastin production. ‘

PLLA (SCULPTRA) 

PLLA stimulates Collagen I and III via mild inflammatory response. Known for subtle, progressive volume enhancement, it is ideal for patients seeking natural, “indetectable beauty.” Sculptra is particularly effective for high-volume areas such as the buttocks, hips, and abdomen. These areas often require 20 to 30 vials per session for the buttocks, 17 mL dilution for the knees and abdomen, and 8cc water +/- 1cc lidocaine per vial. PLLA also promotes angiogenesis and upregulates tropoelastin, contributing to smoother texture and improved skin tone. 

HEAD-TO-HEAD: CAHA VS. PLLA

• Collagen I Increase: Comparable (CaHA 15%, PLLA 14% in a 6-month period).
• Picrosirius Red Stain (Collagen): CaHA demonstrates higher-intensity staining.
• Elastin Staining: CAHA demonstrated 3.59x higher intensity.
• Elastin Precursors: PLLA upregulates tropoelastin.
• “Glow” effect: Both products contribute to visible skin radiance. 

CLINICAL PEARLS AND COMPLICATION MANAGEMENT 

Dr. Durairaj frequently uses both agents in her practice, combining Radiesse in the cheeks and jawline for immediate lift, and Sculptra in the temples, pre-auricular area, and pre-jowls to build volume over time—which can be thought of as the “Velcro effect.” The most significant complication is nodule formation, often due to incorrect depth of injection. Recommended practices include: 

• Depth control.
• Post treatment massage: The rule of 5 which includes 5 circle massages, 5 times per day, for 5 days. 

CONCLUSION

Biostimulators such as PLLA and hyperdilute CaHA are transforming aesthetic medicine by targeting age-related volume loss and dermal thinning at a cellular level, with a longer-lasting effect compared to traditional gel fillers. Each has unique advantages, and when used skillfully—individually or together—they provide safe, effective, and natural-looking results.