Meet the Team

Dr. Eric Dickerson, DC, FRCms

Founder | Sports Chiropractor | Director of Clinical Development

As the Founder and Director of Clinical Development at Radius Physical + Sports Rehab, Dr. Eric Dickerson is a dedicated musculoskeletal provider who blends clinical expertise with a patient-centered approach. He integrates functional rehabilitation, evidence-based physical rehabilitation modalities, joint manipulation, and advanced manual therapy techniques to craft a comprehensive approach to your health.

Dr. Dickerson emphasizes individualized care rooted in modern movement science. Whether treating acute injuries, chronic pain, or performance limitations, he and the Radius team prioritize function, blending multiple treatment modalities to restore full-body function and optimize physical performance.

Before founding Radius, Dr. Dickerson led a team of providers in Seattle, WA, treating a wide spectrum of conditions—from calf strains and frozen shoulder to low back pain and post-surgical rehabilitation. His commitment to quality care earned him recognition as a Top Doctor by Seattle Met Magazine. In 2017, he relocated to the Sierra Nevada foothills to launch a clinic rooted in clinical integrity, compassion, and forward-thinking rehabilitation.

Dr. Dickerson holds a Bachelor of Science in Kinesiology from Arizona State University and earned Magna Cum Laude honors from Palmer College of Chiropractic in Iowa, where he received the Academic Excellence Award. He served as Vice President of the Palmer Package Club, trained peers in orthopedic and neurological exam protocols, and was an active member of the Sports Council, supporting athlete recovery at competitive events. His global perspective was shaped by humanitarian work providing chiropractic care in Salvador, Brazil.

Originally from the Chicago area, Dr. Dickerson brings the same energy he gives to his patients into his personal life. An advocate for active living, he enjoys golf, basketball, hiking, and softball—though these days, much of his time is spent adventuring with his daughter Kennedy and newborn son Benjamin.

Dr. Chris Whalen, DC, FRCms

Musculoskeletal Rehabilitation | Rehab Chiropractor

Dr. Chris Whalen, DC, FRCms is a highly knowledgeable chiropractor and rehabilitation specialist with a proven track record of helping patients achieve their health and fitness goals. With his Doctor of Chiropractic degree from Palmer College of Chiropractic West, Dr. Whalen brings a wealth of expertise to his practice, ensuring that his patients receive the highest quality of care.

Before pursuing a career in chiropractic, Dr. Whalen honed his skills as a personal trainer at 24 Hour Fitness, where he gained a reputation as a coach who could help clients improve their strength and athleticism. He also earned a Bachelor of Science degree in Kinesiology with an emphasis in Exercise Science from Sonoma State University and gained valuable hands-on experience as an intern in a physical therapy office.

At Palmer College of Chiropractic West, Dr. Whalen was a valued member of the Rehab 2 Performance Club and a dedicated teaching assistant for physical therapy and rehabilitation courses. He has also provided treatment to athletes at various athletic competitions, including the first ACA Sports Council event after the pandemic.

With a lifelong passion for physical activity and a commitment to helping others achieve their health goals, Dr. Whalen is dedicated to helping his patients achieve their best possible health. Whether you're recovering from an injury, looking to improve your strength and athleticism, or simply seeking to live a healthier and more active lifestyle, Dr. Whalen has the expertise and experience to help you achieve your goals. He is excited to bring his skills to the small town of Nevada City, where he is eager to help local residents achieve their best possible health.

Dr. Tristan Ginkel, DC, FRCms

Sports Chiropractor | Functional Range Conditioning Mobility Specialist | Golf Performance Optimizer

Dr. Tristan Ginkel is a passionate and skilled sports chiropractor and Functional Range Conditioning mobility specialist based in Grass Valley, California, dedicated to helping patients move better, feel stronger, and perform at their best. Originally from Gilroy, CA, Dr. Tristan brings a warm, personable approach to care—blending cutting-edge techniques with a sincere commitment to each patient’s health journey. Known for his kindness, approachability, and family-first values, he strives to create a supportive and empowering experience for every individual he treats.

A 2022 graduate of Palmer College of Chiropractic, Dr. Tristan has already gained robust clinical experience in both sports performance and neuropathy-focused chiropractic care. He is certified in Functional Range Conditioning (FRC), Myofascial Decompression, and Active Release Technique (ART)—allowing him to offer advanced, evidence-based therapies for patients dealing with muscle tightness, joint restrictions, chronic pain, sports injuries, and mobility limitations. Whether you're an athlete looking to enhance performance, a golfer aiming to improve your swing, or someone seeking relief from everyday aches and pains, Dr. Tristan delivers personalized care tailored to your goals.

Beyond the clinic, Dr. Tristan leads an active, family-oriented lifestyle. He enjoys mountain biking, skiing, golfing, and spending time with his wife and their two dogs in the beautiful Sierra Nevada foothills. His own love for movement and connection to nature fuels his dedication to helping others live fully, pain-free, and on their own terms.

If you're seeking expert care in sports chiropractic, functional movement, injury recovery, or golf performance, Dr. Tristan Ginkel offers the tools, training, and heart to help you reach your full potential. Schedule your appointment today and take the next step toward better mobility, stronger performance, and a more active, fulfilling life.

Dr. Austin Van Poole, DC

Active Rehab Chiropractor | Soft Tissue Specialist | Movement & Performance Optimizer

Dr. Austin Van Poole is a compassionate and results-driven chiropractor based in Yuba City, California, specializing in musculoskeletal rehabilitation, soft tissue therapy, and active care for injury recovery and performance enhancement. Known for his empathetic approach and dedication to patient-centered care, Dr. Van Poole is passionate about helping individuals reduce pain, regain function, and reclaim the active lives they love. Whether treating acute injuries, chronic pain, or sports-related conditions, he delivers personalized care plans focused on movement optimization and long-term wellness.

Dr. Van Poole holds an undergraduate degree in Sports, Exercise, and Wellness, a master's in Education: Administration and Policy, and earned his Doctor of Chiropractic from Parker University. As a former collegiate football player and strength and conditioning coach, he brings firsthand insight into athletic performance, biomechanics, and injury prevention. During his time at Parker, he honed his clinical skills in the university's sports pod, gaining hands-on experience in treating athletes with complex orthopedic needs.

He began his career at Airrosti Rehab Centers, where he developed deep expertise in soft tissue injury treatment, manual therapy, and functional rehab techniques. His approach is grounded in evidence-based care, combining advanced soft tissue techniques with tailored therapeutic exercises. Dr. Van Poole’s patients value his ability to listen deeply, explain clearly, and provide a clear path toward pain relief, improved mobility, and peak performance—all delivered with warmth, encouragement, and clinical excellence.

Now practicing in his hometown of Yuba City, Dr. Van Poole is proud to serve his local community with integrity and heart. When he’s not in the clinic, you can find him spending time with his wife and daughters, staying active outdoors, perfecting his BBQ skills, or playing golf.

Whether you're recovering from an injury, managing back pain, neck pain, or soft tissue strain, or simply looking to improve your mobility and performance, Dr. Van Poole is here to support your journey with expert care and genuine compassion. Book your appointment today and take the next step toward lasting health and movement freedom.

Grafton Prewett, PT, DPT, CCM Certified

Physical Therapist | Concussion & Balance Specialist | Movement Optimizer

Grafton Prewett is a Doctor of Physical Therapy and Neuromusculoskeletal Rehabilitation Specialist with over seven years of clinical experience in helping patients recover from orthopaedic injuries, motor vehicle accidents, concussions, and balance disorders. Based in Grass Valley, California, he provides care for a wide range of patients—from those suffering post-traumatic brain injuries (TBIs) and vestibular dysfunction to older adults navigating fall risk and age-related instability. Grafton is Certified in Complete Concussion Management™ (CCM) and follows the California Department of Industrial Relations Medical Treatment Utilization Schedule (MTUS) to deliver evidence-based care tailored to each patient’s recovery path.

Dr. Prewett specializes in concussion rehabilitation, whiplash-associated disorders, and vestibular therapy, addressing complex symptoms like dizziness, vertigo, headaches, and impaired coordination following car accidents or head trauma. He takes a whole-person approach to movement optimization, combining hands-on manual therapy with functional, goal-driven exercise. His background in exercise physiology (B.S. from California State University, Chico) and advanced training through Chapman University’s Doctor of Physical Therapy program support his dynamic treatment style—one that is both compassionate and rooted in clinical precision. He previously managed a busy PT department within a primary care practice, giving him deep insight into interdisciplinary collaboration and integrated care.

Grafton’s treatment philosophy is active, personalized, and collaborative. He believes that true recovery happens when patients are empowered, engaged, and seen as whole individuals. Fluent in Spanish and conversational in Portuguese, Grafton’s international clinical work in Brazil, Costa Rica, and Haiti has shaped his cultural competency and strengthened his ability to deliver empathetic, accessible care across diverse populations. Outside of the clinic, he lives an adventurous lifestyle filled with skiing, hiking, trail running, golfing, climbing, fishing, and homesteading. He’s also building out a van for future travel—a testament to his love for the outdoors and commitment to staying active. Having personally recovered from several orthopaedic injuries, Grafton brings real-world perspective, resilience, and compassion to every patient interaction.

Whether you're recovering from a concussion, auto accident, chronic pain, or balance issue, Dr. Grafton Prewett is here to help you move better, heal fully, and live more confidently. He is proud to serve the Nevada City and Grass Valley communities with expert care, integrity, and heart.

Ronja Geisser, LMT

Licensed Massage Therapist | Pain Relief & Stress Reduction Specialist

With over 12 years of hands-on experience, Ronja Geisser is a highly skilled and compassionate licensed massage therapist at Radius Physical + Sports Rehab, specializing in therapeutic bodywork for pain relief, injury recovery, and stress management. Trained at the esteemed Hawaiian Islands School of Massage, Ronja brings a deep understanding of both Western clinical techniques and traditional healing arts, offering a comprehensive, client-centered approach to wellness.

Ronja is passionate about helping patients relieve chronic pain, reduce tension, and restore musculoskeletal balance through targeted, evidence-informed care. Her sessions often blend modalities such as myofascial release, trigger point therapy, neuromuscular techniques, Swedish massage, Lomi Lomi, deep tissue therapy, and sports massage—tailored to each individual’s needs. Whether you're recovering from a sports injury, managing chronic tension, or seeking to improve mobility and circulation, Ronja’s work is designed to promote lasting physical and emotional relief.

Outside of the treatment room, Ronja embraces movement, creativity, and nature. She enjoys aerial silks, exploring the outdoors, and living an active, heart-centered lifestyle. Her intuitive touch and thoughtful presence create a healing space where clients feel safe, supported, and empowered on their wellness journey.

If you’re seeking therapeutic massage for injury recovery, chronic pain relief, or relaxation, Ronja Geisser offers the perfect balance of clinical skill and holistic care. Book your massage therapy session today to experience the difference expert, compassionate bodywork can make.

Erin Crow, LMT

Licensed Massage Therapist | Medical Massage & Wellness Specialist

With over 25 years of professional experience, Erin is a trusted and deeply compassionate licensed massage therapist at Radius Physical + Sports Rehab, offering personalized bodywork for pain relief, injury rehabilitation, and holistic wellness. Her extensive background in medical massage allows her to serve a diverse range of clients—including athletes, seniors, and individuals recovering from injury—with precision and empathy.

Erin specializes in Swedish massage, Esalen deep bodywork, myofascial release, prenatal massage, and elder care massage therapy, using an integrative approach to support the body’s natural healing process. Her sessions often combine deep tissue techniques, relaxation-based bodywork, and Reiki energy therapy to treat conditions such as chronic pain, muscle overuse, tension-related headaches, and post-surgical recovery. Whether addressing acute sports injuries or long-standing muscular imbalances, Erin delivers skilled, intentional care that supports mobility, stress reduction, and long-term recovery.

Known for her calming presence and intuitive touch, Erin blends clinical knowledge with a whole-person approach to meet each client exactly where they are in their healing journey. She is committed to providing results-driven care that nurtures both the physical body and emotional well-being, making her an invaluable resource for those seeking therapeutic massage therapy in Grass Valley and the surrounding area.

If you’re looking for expert massage therapy for injury recovery, chronic pain relief, prenatal support, or elder wellness, Erin offers the experienced hands and heart you can trust. Schedule your session today and experience the healing power of personalized bodywork.

Serene Renschler

Rehabilitation Specialist

Eric Bachman

Rehabilitation Specialist

Nick Moultrie

Rehabilitation Specialist

Susan Ross

Referral Coordinator

Susie plays an integral role in maintaining Radius' commitment to patient advocacy. As the primary point of contact for our workers' compensation, motor vehicle accident, and personal injury cases, she consistently goes above and beyond for our patients.

Susie's meticulous attention to detail and exceptional communication skills ensure a smooth process for everyone involved. Her dedication is widely recognized and deeply appreciated by both our staff and our patients.

When she’s not assisting patients, you’ll likely find Susie with her animals exploring the great outdoors—hiking, backpacking, and staying active!

Karen Wallack-Eisen

Front Office Coordinator | Community Connector Extraordinaire

Karen’s journey with Radius Physical + Sports Rehab began in 2017—not as an employee, but as one of Dr. Eric Dickerson’s very first patients. Since then, she has become an irreplaceable part of the Radius team, known for her deep ties to the Nevada County community, her compassionate energy, and the friendly way she seems to know half of the patients who walk through our doors.

Originally from New Jersey, Karen relocated to Northern California in 1980 after a spontaneous cross-country road trip. She earned her degrees in Sociology and Criminal Justice from Rutgers University and later completed her Early Childhood Education credential from San Francisco State University—an educational journey that eventually led her to serve as a Teacher Trainer for the California Department of Education. She also founded Tiny Pines Early Learning Center, the area’s first infant- and toddler-focused childcare program.

Karen's passion for education, community, and connection is evident in her involvement with Sierra Dance Institute, Nevada Union High School’s athletics, and her work with homeless families at the Grass Valley Family Resource Center. She joined Radius nearly four years ago and continues to greet every patient with energy, warmth, and her trademark purple hair. She’s also a committed runner, completing multiple half marathons and participating in the Run the Year Challenge, tracking over 2,000 miles annually through running, walking, and biking.

When she’s not brightening up the clinic or coordinating care, you’ll find her training at Anytime Fitness, decorating the office for every season, or bonding with patients over pets—especially if they bring their dogs. Karen is a powerhouse of heart, humor, and community spirit, and we’re lucky to have her as part of the Radius family.

Natalie Collins

Remote Office Manager | Patient Care Coordinator | Nutrition & Wellness Advocate

As the Remote Office Manager at Radius Physical + Sports Rehab, Natalie Collins may not be the face you see when you walk into the clinic—but she’s often the first voice you hear, and the one ensuring your experience is smooth, informed, and personalized from the very beginning. With a calm and compassionate presence, Natalie helps patients navigate the scheduling process, answers questions with care, and matches each individual with the right provider based on their condition—whether it’s low back pain, a shoulder injury, post-accident rehabilitation, or routine chiropractic care.

Natalie brings a strong background in healthcare, nutrition, and small business operations. She earned her Bachelor of Science in Nutrition, Food Science & Management from California State University, Chico, and has worked as a Dietetic Technician in clinical settings. For over six years, she successfully operated her own wellness-based small business, gaining deep experience in client care, administration, and community engagement. She’s also a certified yoga instructor with over 13 years of practice, blending her knowledge of movement and mindfulness into her everyday life and work. Her ability to connect with people, anticipate needs, and support both patients and providers makes her a vital part of the Radius team.

Originally from San Diego, California, Natalie relocated to Tennessee three years ago but remains deeply connected to her Northern California roots. When she’s not helping patients, you’ll find her embracing an active, wellness-centered lifestyle—doing hot yoga, gardening, hiking the trails, playing with her dog, mushroom foraging, teaching and taking cooking classes, or volunteering with local community organizations. Her passion for helping others feel their best—both physically and emotionally—shines through in everything she does, making her an invaluable resource for patients and the broader Radius community.

Juli Bachman

Front Office Coordinator | Patient Support Specialist | Wellness Advocate

As one of the welcoming Front Office Coordinators at Radius Physical + Sports Rehab, Juli Bachman is often the first face you’ll see when you walk into our clinic. With a warm smile and a calming presence, Juli plays a key role in ensuring each patient’s experience is smooth, efficient, and supported from the moment they arrive. Whether she’s checking patients in and out, managing appointment scheduling, or coordinating with our chiropractors, physical therapists, and rehab specialists, Juli keeps the front end of Radius running seamlessly.

Juli’s background as a former biology teacher gives her a solid foundation in anatomy and physiology, which enhances her ability to understand and support our patients’ needs. Her strong organizational skills, attention to detail, and compassionate communication make her an essential bridge between our care providers and the patients we serve. She works behind the scenes with administrators and directly with patients to ensure everyone receives the care and information they need—especially those navigating complex care plans, physical therapy schedules, or workers’ compensation and personal injury cases.

Outside of the clinic, Juli lives a vibrant, wellness-centered life. She enjoys practicing and teaching yoga, gardening, baking wholesome foods, and walking her beloved dogs. Having overcome her own health challenges, injuries, and surgical recoveries, Juli brings authentic empathy, resilience, and understanding to her role. Her firsthand experience with healing helps her connect deeply with patients and provide the kind, grounded support that sets Radius apart.