PDO Thread Lift Training: Certification & Complete Course Guide
The PDO thread lift has emerged as one of the most sought-after non-surgical facial rejuvenation procedures in aesthetic medicine. Offering a middle ground between dermal fillers and surgical facelifts, thread lifts provide visible lifting and tightening results without the downtime, scarring, or risk associated wit...
PDO Thread Lift Training: Certification & Complete Course Guide
Introduction
The PDO thread lift has emerged as one of the most sought-after non-surgical facial rejuvenation procedures in aesthetic medicine. Offering a middle ground between dermal fillers and surgical facelifts, thread lifts provide visible lifting and tightening results without the downtime, scarring, or risk associated with surgery. For medical professionals looking to expand their aesthetic skills, PDO thread training represents an opportunity to master a high-value procedure with growing patient demand.
Industry data shows that thread lift procedures have grown 15-20% annually over the past five years, driven by patient desire for natural-looking results, minimal downtime, and treatments that address structural aging rather than just volume loss. Social media has amplified interest in thread lifts, with millions of views on treatment demonstrations and before-and-after results. This visibility has educated consumers and created unprecedented demand for skilled practitioners.
This comprehensive guide explores everything you need to know about PDO thread training, from understanding the different types of threads and their applications to choosing a quality training program and building a successful thread lift practice. Whether you are a physician, nurse practitioner, physician assistant, or other qualified provider, understanding the training pathway for thread lifts will help you make informed decisions about adding this valuable procedure to your skill set.
What Are PDO Threads?
PDO stands for polydioxanone, a synthetic absorbable suture material that has been used safely in surgery for decades. In aesthetic medicine, PDO threads are specially designed sutures that are inserted into the subcutaneous layer of the skin to lift sagging tissue, stimulate collagen production, and improve overall skin quality.
How PDO Threads Work
Thread lifts achieve results through two primary mechanisms. First, the physical placement of threads provides immediate mechanical support and lifting of descended tissue. Barbed threads, in particular, anchor into tissue to reposition sagging skin and create visible contour improvement right after the procedure. Second, the threads trigger the body's healing response, stimulating fibroblast activity and collagen synthesis around the threads. This neocollagenesis continues for several months after insertion, gradually improving skin quality, texture, and firmness.
Safety and Biocompatibility
PDO has an excellent safety profile based on decades of use in surgical applications. The material is fully absorbable, breaking down through hydrolysis over 6-8 months and being naturally eliminated by the body. Because PDO is synthetic rather than biological, there is virtually no risk of allergic reaction or disease transmission. The threads stimulate collagen production during the absorption process, meaning that even as the threads dissolve, the structural improvement they created is maintained by newly formed tissue.
Duration of Results
The immediate lifting effect from thread placement lasts while the threads maintain their structural integrity, typically 6-12 months depending on thread type, placement, and individual factors. However, the collagen stimulation effect extends beyond thread absorption, with many patients maintaining improvement for 18-24 months or longer. Optimal results are often achieved through maintenance treatments every 12-18 months, creating sustained improvement over time.
Comparison to Other Suture Materials
While PDO is the most common thread material, other options exist. Polylactic acid (PLA) threads are stronger and last longer, absorbing over 12-18 months rather than 6-8 months, but they can be more prone to visible irregularities in thin-skinned individuals. Polycaprolactone (PCL) threads have the longest duration, lasting up to 24 months, but they are less commonly used in aesthetic applications. PDO remains the gold standard for most thread lift applications due to its balance of effectiveness, safety, and predictability.
Types of PDO Threads
Understanding the different thread types and their appropriate applications is fundamental to PDO thread training. Each thread design serves specific purposes and produces different results.
Thread Type Comparison
| Thread Type | Structure | Primary Use | Lifting Power | Collagen Stimulation |
|---|---|---|---|---|
| Mono/Smooth | Single smooth filament | Skin tightening, fine lines | Minimal | Moderate |
| Screw/Twist | One or two threads twisted | Volume restoration, contouring | Minimal | High |
| Cog/Barbed | Threads with directional barbs | Lifting sagging tissue | High | Moderate to high |
Mono Threads (Smooth Threads)
Mono threads are the simplest PDO threads, consisting of a single smooth filament without barbs or twists. They are inserted in multiple parallel or cross-hatched patterns to create a mesh-like support structure beneath the skin. Mono threads do not provide significant lifting but excel at improving skin texture, reducing fine lines, and tightening mild laxity. They work primarily through collagen stimulation rather than mechanical support.
Common applications for mono threads include addressing forehead lines, crow's feet, under-eye crepiness, perioral lines, and neck texture. They are often used in combination with other thread types or as a standalone treatment for patients with good underlying structure who want subtle skin quality improvement.
Screw Threads (Twist Threads)
Screw threads feature one or two PDO filaments twisted around a needle, creating a spiral configuration. When inserted, they provide more volume and dimensional support than mono threads without the aggressive lifting action of barbed threads. The twisted structure creates more surface area for collagen stimulation, making these threads particularly effective for restoring volume to hollowed areas.
Screw threads are ideal for treating nasolabial folds, marionette lines, hollow temples, sunken cheeks, and areas that need volumization without dramatic lifting. They can serve as an alternative to dermal fillers for patients who prefer bioabsorbable treatments or have had complications with fillers.
Cog Threads (Barbed Threads)
Cog threads are the workhorses of thread lifting, featuring small barbs or cogs along the thread length that anchor into tissue to physically lift and reposition descended structures. These threads come in various configurations including uni-directional barbs (all facing one direction), bi-directional barbs (facing opposite directions from a central point), and multi-directional barbs (facing multiple directions for stronger anchoring).
Barbed threads provide the most dramatic and immediate lifting results. They are used for mid-face lifting, jowl reduction, neck lifting, brow elevation, and jawline definition. The insertion technique is more complex than mono or screw threads, requiring precise understanding of facial anatomy and tissue planes to achieve natural-looking results while avoiding complications.
Comprehensive AAOPM PDO thread lift training covers all thread types and teaches you to select the appropriate threads for each patient's anatomy and aesthetic goals.
PDO Thread Lift Procedures
Thread lifts can be customized to address various aging concerns and anatomical areas. Understanding the range of procedures helps you identify the applications most relevant to your practice.
Mid-Face Lift
The mid-face lift is one of the most popular thread lift applications, targeting the cheeks, nasolabial folds, and under-eye area. Cog threads are inserted through small entry points near the hairline or temple, then advanced through the subcutaneous tissue to anchor and lift descended mid-face fat pads. The procedure typically uses 4-8 threads per side depending on the degree of laxity and desired outcome. Results include elevated cheeks, softened nasolabial folds, and improved under-eye appearance. The mid-face lift creates a refreshed, youthful appearance without the extended recovery of surgical intervention.
Jawline Definition and Jowl Reduction
Loss of jawline definition is one of the most aging facial changes, creating a heavy lower face appearance. Thread lifting of the jawline uses cog threads inserted from behind the ear or below the mandible to lift descended tissue and recreate a sharp jawline angle. The procedure tightens mild to moderate jowling and can be combined with neck threads for comprehensive lower face rejuvenation. Results are immediately visible and continue to improve as collagen forms around the threads. Patients often describe feeling like they look "how they remember themselves" rather than artificially enhanced.
Neck Lift
The neck is notoriously difficult to treat non-surgically, making thread lifting an attractive option for patients with early to moderate neck laxity. Horizontal mono threads inserted in a cross-hatch pattern improve neck texture and mild platysmal banding. Vertical cog threads lifted toward the mastoid area can tighten moderate skin laxity. The procedure cannot address severe neck aging or significant muscle banding that requires surgical intervention, but it provides meaningful improvement for appropriate candidates. Neck thread lifts are often combined with jawline threads for comprehensive lower face and neck rejuvenation.
Brow Lift
Thread brow lifts elevate descended brows and reduce forehead and glabellar lines without the prolonged swelling and altered hairline that can occur with surgical brow lifts. Threads are inserted through small entry points in the hairline and directed anteriorly to lift and reposition brow tissue. The procedure requires only local anesthesia and patients return to normal activities within a day or two. Results are subtle but noticeable, creating a more open, alert eye appearance. Brow thread lifts work best for mild to moderate brow ptosis in patients who want to avoid surgery.
Nose Thread Rhinoplasty
Thread rhinoplasty uses PDO threads to reshape the nose by lifting the nasal tip, smoothing dorsal irregularities, or narrowing the nasal bridge. This application is popular in Asian markets and is gaining interest globally for patients who want minor nasal refinement without surgery. The procedure does not reduce nasal size or correct significant structural issues, but it can improve nasal contour for appropriately selected candidates. Thread rhinoplasty requires specialized training beyond basic thread lift skills due to the complexity of nasal anatomy and the potential for vascular complications.
Developing expertise in facial anatomy and treatment planning is essential for all these applications. Many practitioners pursue comprehensive facial aesthetics training that includes thread lifts along with neurotoxins, fillers, and other procedures for complete facial rejuvenation skills.
What PDO Thread Training Covers
Quality PDO thread training prepares you for safe, effective practice through a combination of theoretical knowledge and hands-on skill development.
Facial Anatomy for Threading
Detailed understanding of facial anatomy is perhaps the most critical component of thread training. Unlike some aesthetic procedures where minor anatomical imprecision is forgiving, thread placement requires exact knowledge of tissue layers, danger zones containing nerves and vessels, and anatomical variations between individuals. Training addresses fascial layers and proper insertion planes, location and course of facial nerves to avoid, facial artery and vein anatomy and danger zones, superficial musculoaponeurotic system (SMAS) and its relationship to thread placement, and anatomical variations based on age, ethnicity, and individual differences.
Comprehensive anatomy education often includes cadaver demonstration or detailed anatomical modeling to visualize three-dimensional relationships that are difficult to appreciate from textbooks alone.
Thread Selection and Treatment Planning
Knowing which threads to use for each patient and concern separates excellent outcomes from disappointing ones. Training teaches patient assessment and identification of primary concerns, matching thread types to specific anatomical issues, determining appropriate thread number and placement patterns, combining different thread types for comprehensive rejuvenation, and setting realistic expectations based on degree of aging and tissue quality.
Treatment planning is both an art and a science. Experienced instructors share their approach to patient assessment and decision-making, helping you develop clinical judgment that translates to satisfied patients and strong outcomes.
Insertion Techniques
The technical skill of inserting threads safely and effectively requires extensive hands-on practice. Training covers proper patient positioning and marking techniques, local anesthesia administration for patient comfort, entry point selection to maximize results and minimize visibility, insertion angles and depths for different facial areas, techniques for anchoring and tensioning barbed threads, avoiding complications through proper technique, and managing immediate post-insertion adjustments.
Repetition is key to developing smooth technique. Quality programs provide multiple opportunities to practice on live models under instructor supervision, with feedback to refine your approach.
Combination Treatments
Thread lifts are often performed in combination with other aesthetic procedures for enhanced results. Training addresses combining threads with neurotoxins for wrinkle reduction, pairing threads with dermal fillers for volume and lift, using threads with skin tightening devices like radiofrequency, timing and sequencing of combination treatments, and how to avoid complications when layering multiple modalities.
Learning to think about facial rejuvenation comprehensively rather than as isolated procedures allows you to develop sophisticated treatment plans that deliver superior outcomes.
Complication Management
While thread lifts are generally safe when performed by trained practitioners, complications can occur. Training prepares you to prevent and manage bruising and swelling, thread visibility or palpability, dimpling or skin irregularities, asymmetry or inadequate correction, infection (rare but serious), and rare vascular complications.
Understanding what can go wrong and how to address it is essential for responsible practice. Training includes recognizing complications early, appropriate intervention, and knowing when to refer patients for additional management.
Who Can Perform Thread Lifts?
The legal scope of practice for thread lifts varies by state and professional licensure. Understanding who can perform these procedures in your jurisdiction is essential before pursuing training.
Physicians (MD/DO)
Physicians across all specialties can legally perform thread lifts within their scope of competence. Thread lifts are most commonly performed by dermatologists, plastic surgeons, facial plastic surgeons, and physicians practicing aesthetic medicine, but family medicine doctors, emergency medicine physicians, and others also successfully offer the procedure after proper training. Physicians have the broadest scope of practice and fewest regulatory restrictions for performing thread lifts.
Nurse Practitioners
Nurse practitioners can perform thread lifts in most states, though the level of physician oversight required varies. In full practice authority states, nurse practitioners may perform thread lifts independently after appropriate training. In restricted or reduced practice states, NPs may need a collaborating physician agreement or supervision. The specific requirements depend on state nurse practice acts and regulations. NPs should verify their state's regulations regarding invasive aesthetic procedures before pursuing thread training.
Physician Assistants
Physician assistants typically work under physician supervision and can perform thread lifts as delegated procedures in most states. The supervising physician should review the PA's training and credentials, and the collaborative agreement should specifically mention thread lifts or invasive aesthetic procedures. Some states require the supervising physician to be on-site during procedures, while others allow general supervision. PAs interested in thread lifts should discuss with their supervising physician and review state PA practice regulations.
Dentists
In some states, dentists can perform thread lifts, particularly in the lower face and perioral regions that fall clearly within the anatomical scope of dental practice. State dental boards have varying positions on aesthetic procedures performed by dentists. Some explicitly allow facial aesthetic procedures, others restrict practice to areas affecting oral function, and some prohibit cosmetic procedures outside the mouth entirely. Dentists should consult their state dental board before pursuing thread training.
Registered Nurses
Registered nurses generally cannot perform thread lifts independently, though regulations vary by state. Some states allow RNs to perform invasive aesthetic procedures including thread lifts under physician delegation with appropriate training. Others restrict RNs to less invasive procedures like facials or chemical peels. Thread lifts require tissue manipulation and insertion of devices beneath the skin, which many state boards classify as beyond RN scope. Nurses interested in thread lifts should pursue advanced practice certification (NP) in states where RN practice is restricted.
Understanding professional scope of practice is part of comprehensive training. Learn more about physician aesthetics training and scope of practice considerations for different provider types.
PDO Thread Training Requirements
Successfully completing PDO thread training requires meeting certain prerequisites and committing to the educational process.
Professional Licensure
All reputable thread training programs require active professional licensure as a physician, nurse practitioner, physician assistant, or (in some cases) dentist. Your license must be in good standing without restrictions or disciplinary actions. Training organizations verify licensure as part of the enrollment process to ensure only qualified professionals receive training.
Prior Aesthetic Experience
While not always required, prior experience with aesthetic procedures significantly benefits learning thread techniques. Familiarity with facial anatomy from performing neurotoxin injections or dermal filler treatments accelerates understanding of thread placement. Experience managing aesthetic patients helps with consultation skills and expectation setting. Some advanced thread programs do require documentation of prior aesthetic training as a prerequisite, though basic thread courses often accept participants without prior aesthetic experience.
Insurance and Credentialing
Before offering thread lifts in practice, ensure you have appropriate professional liability insurance that covers aesthetic procedures. Some malpractice carriers require notification or approval before performing new procedures, and a few exclude aesthetic services entirely. Review your policy and discuss thread lifts with your insurance carrier. You may need to provide documentation of your training to receive coverage. If working in a hospital or ambulatory surgery center, you may need to complete credentialing that includes submitting training certificates and potentially demonstrating competence.
State-Specific Requirements
Some states have additional requirements for performing aesthetic procedures beyond professional licensure and training. This might include registering your practice as a medical spa or aesthetic facility, meeting specific facility requirements for invasive procedures, submitting training credentials to your state licensing board, or working under specific supervisory arrangements. Research your state's requirements early in the training consideration process to avoid surprises after completing training.
How Long Is Training?
PDO thread training programs vary in length based on comprehensiveness and format, but most follow similar time frames.
One-Day Intensive Courses
Basic thread lift training can be completed in a single intensive day, typically 8-10 hours. These courses cover fundamentals including thread types and selection, basic facial anatomy, insertion techniques for common applications like mid-face and jawline, and hands-on practice on live models. Single-day courses prepare you to begin performing basic thread lifts under supervision but may not cover advanced applications or complex cases. These programs work well for practitioners who want to start offering threads and plan to develop expertise through practice and additional education.
Two-Day Comprehensive Programs
Most thread training follows a two-day format that provides more depth and practice time. The first day typically focuses on theory, anatomy, patient selection, and technique demonstration. The second day emphasizes hands-on practice with multiple live models, allowing participants to perform various thread lift procedures under supervision. Two-day programs generally cover a wider range of applications including neck lifts, brow lifts, and combination treatments. Participants leave feeling more confident and prepared for independent practice than after single-day courses.
Advanced and Specialized Training
After mastering basic thread techniques, many practitioners pursue advanced training in specialized applications like thread rhinoplasty, barbed thread techniques for maximum lift, combination protocols with other modalities, or revision techniques for suboptimal prior thread procedures. Advanced courses typically run one to two days and assume participants have experience performing basic thread lifts. These programs help practitioners refine techniques, address complex cases, and differentiate their practices with specialized offerings.
Post-Training Practice Period
Beyond the formal training days, plan for a practice period where you perform thread lifts at a slower pace with extra caution. Most practitioners find they are comfortable and efficient by their 15th to 20th thread procedure. The first several cases may take 60-90 minutes as you carefully follow protocols, but experienced practitioners typically complete thread lifts in 30-45 minutes depending on the complexity and number of threads used.
Revenue Potential
PDO thread lifts represent one of the most profitable procedures in aesthetic medicine, with strong demand and healthy profit margins.
Procedure Pricing
Thread lift pricing varies by geographic market, provider credentials, and specific procedure, but typical ranges include mid-face lift using 6-8 threads at $1,500-$2,500, jawline and jowl treatment using 4-8 threads at $1,500-$2,500, neck lift using 10-15 threads at $2,000-$3,000, full face thread lift (mid-face, jawline, and neck) using 15-25 threads at $3,500-$5,000, and brow lift using 2-4 threads at $800-$1,500.
Premium practices in major metropolitan areas command pricing at or above these ranges, while practices in smaller markets or those focused on accessibility may price somewhat lower. The key is to price appropriately for your market while ensuring profitability.
Cost of Goods
PDO threads typically cost between $10 and $40 per thread depending on type, brand, and purchasing volume. A mid-face lift using 8 threads might have thread costs of $120-$240. Adding local anesthetic, needles, antiseptic, and other supplies brings total supply costs to approximately $150-$300 per procedure. Even at the higher end, profit margins on a $2,500 thread lift are 80-90%, making this one of the most lucrative aesthetic procedures.
Patient Volume and Recurring Revenue
Thread lift patients typically return for maintenance treatments every 12-18 months to sustain results. This creates recurring revenue that compounds over time. Additionally, thread lift patients frequently become interested in other aesthetic services you offer. A patient who receives a thread lift might add neurotoxins, skin care treatments, or other procedures, increasing lifetime value significantly. Many practices find that thread lifts serve as a gateway procedure that introduces patients to comprehensive aesthetic care.
Practice Impact
Adding thread lifts can substantially impact practice profitability. A practitioner performing just two thread lifts per week at an average fee of $2,500 generates $260,000 in annual revenue from this procedure alone. With profit margins of 80-85%, this translates to over $200,000 in profit contribution. For many practices, thread lifts become one of the highest-revenue procedures despite representing a modest percentage of total treatment volume.
PDO Threads vs Surgical Facelift
Patients frequently ask how thread lifts compare to surgical facelifts. Understanding the distinctions helps with appropriate patient selection and expectation setting.
Degree of Correction
Surgical facelifts provide more dramatic correction of moderate to severe facial aging. They can address substantial skin excess, deep jowling, significant neck laxity, and underlying muscle laxity that thread lifts cannot fully correct. Thread lifts work best for mild to moderate aging, offering visible but subtle improvement. The analogy often used is that thread lifts can "turn back the clock" 5-7 years, while surgical facelifts can achieve 10-15 years of rejuvenation.
Recovery and Downtime
The recovery advantage of thread lifts is substantial. Most thread lift patients experience 3-7 days of swelling and bruising, with many returning to work within 2-3 days. Surgical facelift patients face 2-3 weeks of significant swelling and bruising, with 4-6 weeks before they look completely normal. For patients who cannot accommodate extended recovery, thread lifts provide a practical alternative.
Risks and Complications
Both procedures carry risks, but the severity and frequency differ. Thread lift complications are typically minor and self-limited, including bruising, swelling, temporary dimpling, thread visibility or palpability, and rarely infection. Surgical facelift complications can be more serious, including hematoma requiring drainage, nerve injury with potential permanent effects, extensive scarring, skin necrosis in severe cases, and anesthesia-related complications. The lower risk profile of thread lifts appeals to patients who want improvement but are risk-averse.
Cost Considerations
Thread lifts cost significantly less than surgical facelifts. A comprehensive thread lift might cost $3,000-$5,000, while surgical facelifts typically range from $15,000 to $30,000 or more including surgeon's fee, anesthesia, and facility costs. However, because thread results are temporary and maintenance treatments are needed, the long-term cost of thread lifts can approach that of surgery if treatments are repeated over many years. The appropriate choice depends on the patient's degree of aging, financial considerations, recovery constraints, and risk tolerance.
Patient Selection
Neither procedure is inherently better than the other; they serve different patient populations. Thread lifts are ideal for patients in their 30s to 50s with mild to moderate aging, those who want to delay surgery, patients who cannot accommodate surgical recovery, or individuals seeking subtle, natural-looking results. Surgical facelifts are more appropriate for patients over 50 with significant aging, those with substantial skin excess and deep jowling, patients who want maximum correction, or individuals willing to undergo a one-time more invasive procedure for longer-lasting results.
Frequently Asked Questions
Are PDO threads safe?
Yes, PDO threads are very safe when inserted by properly trained practitioners. Polydioxanone has been used in surgical sutures for decades with an excellent safety profile. The material is fully absorbable and biocompatible, with virtually no risk of allergic reaction. Complications from thread lifts are generally minor and temporary, most commonly involving bruising, swelling, or mild asymmetry that resolves with time or minor adjustment. Serious complications like infection or nerve injury are rare, occurring in less than 1% of procedures when performed by trained providers following proper technique. The safety profile is significantly better than surgical facelifts, which carry higher risks of hematoma, nerve damage, and anesthesia complications. That said, any invasive procedure carries some risk, making proper training, patient selection, and technique essential. Patients should choose experienced, trained practitioners and follow all pre- and post-treatment instructions to minimize complications.
How much does PDO thread training cost?
PDO thread training programs typically cost between $2,500 and $5,000 depending on the length of training, reputation of the training organization, and what is included. Single-day basic courses are at the lower end of this range, around $2,500-$3,500. Comprehensive two-day programs that include extensive hands-on practice and advanced techniques typically cost $3,500-$5,000. Some programs include starter thread kits in the tuition, while others require separate purchase of practice supplies. Advanced or specialized thread training for practitioners with prior experience usually costs $2,000-$3,500 for one to two days. While the upfront investment is significant, thread training pays for itself quickly. Performing just 2-3 thread lift procedures covers your training cost, and the skill provides income-generating opportunity throughout your career. Many practitioners consider thread training one of their best professional investments. Some training organizations offer payment plans to make the cost more manageable, and the training is tax-deductible as a professional development expense.
Can thread lifts be combined with other aesthetic procedures?
Yes, thread lifts combine beautifully with other aesthetic treatments and are often performed as part of comprehensive facial rejuvenation plans. Threads are frequently combined with neurotoxins like Botox to address both structural aging (treated by threads) and dynamic wrinkles (treated by neurotoxins). Many practitioners perform both procedures in a single appointment. Threads also pair well with dermal fillers, with threads providing lift and fillers restoring volume. The timing and sequencing depend on practitioner preference and specific treatment areas. Some perform fillers first, others do threads first, and some do them simultaneously. Thread lifts can be combined with skin resurfacing treatments like lasers, chemical peels, or microneedling, though these are usually spaced several weeks apart to avoid excessive inflammation. Radiofrequency or ultrasound skin tightening treatments complement threads by addressing skin laxity while threads provide structural support. The key is understanding how treatments interact and proper timing to optimize results while minimizing complications. Comprehensive facial aesthetics training teaches you to develop integrated treatment plans that layer multiple modalities for superior outcomes.
Master PDO Thread Lifts with Expert Training
PDO thread lifts represent the cutting edge of non-surgical facial rejuvenation, offering dramatic results with minimal downtime. For aesthetic practitioners, mastering thread techniques opens the door to serving patients who want more than fillers can provide but aren't ready for surgery. The skill set you develop through thread training will serve you throughout your career, providing both professional satisfaction and strong financial returns.
Master PDO thread lifts with AAOPM's hands-on training. Learn from experienced physician instructors who perform hundreds of thread procedures annually and can teach you the nuances that separate good results from great ones. AAOPM's comprehensive curriculum covers anatomy, technique, patient selection, complication management, and business strategies for building a successful thread practice. With small class sizes ensuring personalized attention and extensive hands-on practice with live models, you will leave training with the confidence and competence to immediately begin offering this high-demand procedure.