Modified Injection Technique for Improving the Treatment of Keloids
Keloids are a specific type of scar that extends beyond the original wound boundary and is unlikely to shrink spontaneously. Despite the availability of various treatment methods, including surgical resection, radiation, injection, laser therapy, and cryotherapy, no single method guarantees a complete cure. Among these, intralesional steroid injection is widely used. Studies have shown that injecting glucocorticoids combined with 5-fluorouracil (5-FU) into keloids can soften the texture, reduce the volume, and alleviate associated symptoms. However, the conventional intralesional injection technique, which involves direct multipoint injection into the keloid parenchyma, often causes significant pain and may not evenly distribute the drug within the firm and tight fibrous structure. This can reduce therapeutic efficacy and patient compliance. To address these issues, a modified injection technique was developed, involving a two-step process: first injecting into the keloid’s base and then into the parenchyma.
The study included 50 patients with keloids who met the clinical diagnostic criteria and were over 18 years old. Exclusion criteria included unwillingness to complete follow-up procedures, recent treatment with surgery, radiation, injection, laser, or cryotherapy, systemic diseases such as hypertension or diabetes, infected keloids, and keloids larger than 9 cm². Patients were equally allocated to either the experimental group, which received the modified injection technique, or the control group, which received the conventional technique. The thickness and hardness of keloids were evaluated using ultrasound and ultrasonic shear wave elastography, respectively. Pain intensity was rated by patients on a scale from 0 to 10 immediately after each injection. The drug mixture consisted of 0.6 mL of 2.5% 5-FU, 5 mL of 1% triamcinolone acetonide, and 1 mL of 2% lidocaine, with a total dose of 0.2 mL/cm³ injected intralesionally.
In the experimental group, one-third of the dose was injected into the keloid base using a 29-G needle, followed by the remaining two-thirds injected into the parenchyma 5 minutes later in a multipoint manner. The keloid base was identified by inserting the needle through adjacent normal skin at an angle of approximately 30° until reaching the base, which is softer than the parenchyma but harder than subcutaneous tissue. The needle was then positioned parallel to the skin to release the drug. This procedure was repeated every 3 weeks for each patient.
One patient in the experimental group and three patients in the control group were lost to follow-up, leaving 46 patients (67 keloids) for analysis. The keloids in the experimental group showed an average thinning of 2.45 ± 1.19 mm after three modified injections, compared to 1.84 ± 0.97 mm in the control group, indicating significantly greater efficacy (P = 0.0125). The elastic modulus (Young modulus) was also reduced more significantly in the experimental group (95.93 ± 69.10 kPa) than in the control group (56.81 ± 33.45 kPa, P = 0.004). Pain scores during the first modified injection were 3.16 points lower than those during conventional injections (5.75 ± 0.85 vs. 8.91 ± 0.97, P < 0.0001). No significant differences in side effects were observed between the two groups.
The modified injection technique achieved better therapeutic outcomes by facilitating even drug distribution and directly affecting the nourishing blood vessels at the keloid base. Hematoxylin and eosin staining revealed that the basal layer of keloids is looser than the central part, with larger gaps between collagen fibers, which aids in drug dispersion. Ultrasound observations showed that hyperactive keloids often have significant nourishing vessels at the base or near the rim, which are directly influenced by the basal injection.
Pain reduction was another significant advantage of the modified technique. The conventional method often causes severe pain due to the firm texture of keloids, even with lidocaine. By first injecting into the keloid base, where collagen density is lower, and allowing lidocaine to take effect, pain during subsequent parenchymal injections was minimized. Common side effects, such as menstrual disorders and acne, were observed in both groups, with two cases of mild tissue depression in each group.
In conclusion, the modified injection technique enhances the effectiveness of keloid treatment by increasing the rate of keloid atrophy and reducing pain during injections. This method improves patient compliance and therapeutic outcomes, making it a valuable advancement in the treatment of keloids.
doi.org/10.1097/CM9.0000000000000804
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