Physical Therapy Staff

Physical Therapy Services 

Our Staff 

Wheaton Location 

Chun Yin Jethro Mak, PT, DPT

Jethro Mak completed his undergraduate studies at West Virginia University in Morgantown, WV. He enrolled in WVU Honors College and earned his Bachelor of Science degree in Exercise Physiology with Summa Cum Laude honors. He later earned his Doctorate of Physical Therapy from the University of Maryland, School of Medicine in Baltimore, MD. During physical therapy school, Jethro had experiences working in various clinical settings, including outpatient orthopedics, inpatient rehabilitation, and skilled nursing facilities. He enjoys working with patients of all ages, as well as a variety of orthopedic and neurological conditions. Jethro believes it is important to develop customized rehabilitation programs, provide appropriate education, and utilize various treatment techniques to help patients achieve their functional goals and best possible outcomes and prevent future injuries.

As a clinician, he is certified in LSVT BIG, an evidence-based, intensive treatment program that helps people with Parkinson’s disease to improve mobility and activities of daily living. He has also honed his treatment skills through continued education focused on orthopedic physical therapy since joining Arthritis & Rehabilitation Therapy Services.

Jethro grew up in Hong Kong and is a native speaker of Cantonese and Mandarin. He enjoys spending time with his family and friends, hiking, playing piano, traveling, and learning different cultures. His personal motto is to “rest in the highest excellence”.

Jethro is an exceptional person! Excellent in his job, and patient with us, good sense of humor and extremely capable! He has helped me a lot!! My quality of life has improved a lot! I am more flexible, have almost no pain and do hundreds of things that were impossible to do before!

Nelly C.  (Patient)

I met Jethro when I was in EXTREME PAIN! With a few sessions, he reduced my pain considerably. I felt very comfortable with his therapy.

V.B.P.  (Patient)

Back and hip surgeries, osteoporosis, arthritis and scoliosis caused me to have a lot of pain. Since working with Jethro there is a definite increase in my leg strength and improvement in my balance. I can walk further without much pain. The program here is thorough and Jethro is very knowledgeable and caring!

Anne E.  (Patient)


Eunice Ahn, PT, DPT, CMTPT


Eunice Ahn is a native of the Montgomery County area. She received her Bachelor of Science degree in Kinesiology from the University of Maryland, College Park. She then earned her Doctor of Physical Therapy degree from the University of Maryland, Baltimore. During her clinical rotations, she gained experience in a variety of settings including outpatient orthopedics, vestibular rehabilitation, inpatient cardiac rehabilitation, and surgical oncology rehabilitation.

Eunice is skilled in treating a variety of patient populations, including patients suffering from acute and chronic pain conditions, general orthopedics, post-operative patients, and balance and vestibular disorders. She believes in a holistic approach and will work with her patients to find the root cause of the pain, rather than treat just the symptoms. Eunice has her certification as a Certified Myofascial Trigger Point Therapist (CMTPT) through Myopain Seminars and uses dry needling in her practice to treat myofascial pain and dysfunction.

Outside of work, Eunice loves to find good eats in the DMV area. She also enjoys working out at the gym and playing with her dogs.

“Eunice prepared me for the surgery with exercises to strengthen the muscles around my knee. Post-surgery I was surprisingly quick to be able to move with confidence. I had a greater range of movement and flexibility. Post-surgery sessions gave me much to work on, which moved the healing and strengthening much further. I am most grateful for her support.” 

Kandy H. (Patient)

“I began PT due to back pain from stenosis, I realized this would be ongoing pain and hoped to learn from physical therapy how to manage it, before turning to injections, etc. Eunice explained in detail and worked to help me cope with the issues. I gradually gained confidence and [learned] the best movements to reduce pain. I was encouraged to try various exercises and how to best optimize their effectiveness — without fear!  Now I can walk and balance my walking with helpful exercises.” 

Anne H. (Patient)

I was referred by my doctor to address my low back pain. My experience with Eunice has been nothing short of excellent. I have more strength and stamina and confidence about managing my health issue. I would rate her highly qualified, professional, and a great therapist. She gets the highest regard and grade from me. It’s been a true pleasure working with her and after my sessions-I always leave refreshed and with a smile on my face. Kudos to Eunice!

Yvette B. (Patient)

Derek Chow, PT, DPT


Derek has practiced physical therapy in a variety of settings, from private to hospital and rehabilitation facilities, treating patients with orthopedic, post-surgical, pediatric, and neurological conditions. He is experienced in treating patients of all ages, from pediatric to geriatric care. He believes in optimizing function in everyday life and taking time to educate patients about their bodies. He developed a passion for helping people through movement from personal experience recovering from his own sports-related injuries. Derek’s treatment approach is eclectic and individualized to the patient, including a combination of manual therapy, therapeutic exercise, and therapeutic activities with a focus on returning a patient to their maximal functional level. While working with Arthritis and Rehabilitation Therapy Services, Derek has further expanded his knowledge and treatment skills through continuing education, including in the use of manual trigger point release and other manual treatment techniques, which are integral components of his practice.

“In the current practice, I enjoy working with a wide variety of patient populations in the local community, meeting wonderful people, and having the opportunity to serve in the DMV area. I love working with patients of all ages and both orthopedic and neurological injuries or diagnoses. I have a passion for learning and improving my skills as a physical therapist and will be pursuing continuing education and certifications to enhance my practice and further benefit my patients.”

Derek grew up in Hong Kong and New York City and is a native speaker of Cantonese. Outside of work, he enjoys weightlifting in the gym, attending concerts, spending time with friends and family, and seeking new adventures.

Rockville Location  

Allison Berger, PT, DPT

Allison grew up in Silver Spring, Maryland, and graduated from Mount Holyoke College with a Bachelor of Arts in Chemistry with a minor in Anthropology in 2014. A phenomenal patient experience led her to pursue a Doctorate in Physical Therapy, which she earned from the University of Maryland, Baltimore in 2021. Allison’s primary childhood movement practice was martial arts, where she began formally teaching both adults and children at age 11. She earned her black belt at age 14 after eight years of study and continued to teach for many years. While she entered PT school to become a pediatric physical therapist, Allison had the opportunity to practice in outpatient geriatrics, neurological inpatient rehabilitation, school-based physical therapy, and outpatient orthopedics. Through the course of her clinical education, Allison developed a passion for optimizing independence in older adults and assisting patients of all ages with reducing and managing chronic pain.

In treating patients, Dr. Berger formulates an individualized plan of care incorporating therapeutic exercises, neuromuscular reeducation, manual therapy, pain-relieving modalities, and patient education aimed at assisting patients in meeting their goals and learning how to best manage their conditions independently. She has a special interest in treating patients with chronic pain, balance deficits, and hypermobility syndrome. Her position as a physical therapist at Arthritis and Rehabilitation Therapy Services allows her to apply her ever-expanding base of knowledge and skills to the specialized treatment of patients with various arthritic and rheumatological conditions. She also enjoys the opportunity to develop her French and Spanish language skills when working with patients.

Rockville Location  

Katie Mills, PT, DPT, CMTPT

Katie Mills, PT, DPT

Katie Mills graduated from the University of Maryland College Park with a Bachelor of Science degree in Kinesiology and Elementary Education. After graduation, she served as a substitute teacher in Montgomery County and enjoyed working with children of different ages. She soon realized that her true passion was helping people and decided to return to school to obtain her Doctorate of Physical Therapy. She entered a DPT program at Nova Southeastern University in Fort Lauderdale, Florida. During graduate studies, she gained physical therapy experience in a variety of clinical settings, including orthopedics, in-patient, and school-based therapy.

After achieving her Doctorate of Physical Therapy in 2017, Katie moved back to the area to be close to her family and pursue a full-time physical therapy career. In her practice, she strives to be a comprehensive diagnostician and clinician and to provide her patients with the best care, utilizing an individualized plan of care for every patient. She uses a variety of treatments, including manual techniques, patient education, neuromuscular re-education, and therapeutic exercises, to achieve optimal outcomes for patients.

While working with Arthritis and Rehabilitation Therapy Services, Katie has further expanded her knowledge and treatment skills through continuing education, including in the use of manual trigger point release and other manual treatment techniques, which are integral components of her practice. Additionally, she achieved certification in Dry Needling from Myopain Seminars and utilizes this practice in her treatment of patients with a variety of neuromuscular, myofascial, and sensitization conditions.

I had a really bad fall in 2006 resulting in permanent disability. Katie has helped me improve my quality of life. P.T. from Katie helped me a lot and I am able to do more things for longer periods of time. One of the most valuable aspects of treatment was learning ways to control the pain. One thing that sets you apart from others is the attention to my specific issues and the attention to a holistic treatment.

Beatriz F.  (Patient)

Katelyn was great to work with while I learned how to expand my range of motion with neck and shoulders. She took the time needed to explain the exercises. She also provided very useful information and materials to assist me now that I have been diagnosed with osteoporosis.

Anne T.  (Patient)

3) I came to ARTS on the recommendation of my rheumatologist for my arthritis; in particular my right hip pain. As I moved from eval to treatment and home exercises, Katelyn always met me where I was. As I noted my progress, and learned about my body, she was “with me” all the way. Together, we saw progress and what needed more work. I was always supported and encouraged in my P.T. She and all the staff are warm and friendly. I received very useful instructions also from Darcy, Kwesi and Brendan. And I heard realistic info and nothing ‘sugar-coated’. Thank you all!

Sara H.  (Patient)

Chevy Chase Location

Danya Czarnolewski, PT, DPT 


Danya graduated from the University of Maryland, College Park with a Bachelor of Science degree in Kinesiology. She then went on to earn her Doctorate of Physical Therapy degree from the University of Maryland, Baltimore. In her time as a physical therapist, she has worked in a variety of settings, including the ICU, step-down unit, and outpatient orthopedic. She enjoys working with patients of all populations and ages and has a special interest in the geriatric, orthopedic, and burn survivor populations. In helping her patients achieve their goals, she utilizes plans of care individualized for each patient, including therapeutic exercise, neuromuscular reeducation, and manual therapy techniques to correct postural and muscular imbalances that lead to dysfunction. Empowering patients through education on their conditions and treatment strategies is extremely important to her. She strives to explain rehabilitation concepts clearly and encourages patients to ask questions and provide feedback about their care, so patients become active participants in their recovery. 

“Danya listened carefully and was very thorough.  I’m back to normal and so grateful.”

Ingrid O. (Patient)

“I came in with shoulder and upper arm pain, Danya did a very thorough evaluation and instituted a plan for in-office therapy and at-home exercises.  I saw improvement fairly quickly… Danya is very good at what she does. Very knowledgeable and has a good temperament for the job.  The information/knowledge gained from Danya about how my arm/shoulder/body works and how to improve it (was most valuable).”

Anita R (Patient)

DC Location

Aidan Bittinger-Esser, PT, DPT

Aidan Bittinger-Esser grew up locally in Silver Spring, Maryland. He earned his Bachelor of Science in Exercise Science at Elon University in North Carolina. Following undergraduate studies, he returned to the Washington, D.C. area and worked as a physical therapist aide in Arthritis and Rehabilitation Therapy Services’ Washington, D.C. office, gaining valuable knowledge and experience in the practice of physical therapy in preparation for his career pursuit as a physical therapist. He then went on to earn his Doctor of Physical Therapy degree at Widener University in Pennsylvania, where he received the Pro Bono National Honor Society Award for his time treating patients in the student-run clinic.

Dr. Bittinger-Esser acquired significant experience treating patients with a wide range of diagnoses and conditions during his clinical rotations, which spanned a variety of clinical settings, including outpatient orthopedics, outpatient neurological rehabilitation, and inpatient rehabilitation. After earning his Doctor of Physical Therapy, Aidan again returned to the Washington, D.C. region and joined Arthritis and Rehabilitation Therapy Services in the Washington, D.C. office to begin his anticipated practice as a licensed physical therapist. Given his prior experience providing care to patients as a physical therapist aide, and knowledge of Arthritis and Rehabilitation Therapy Services’ patient population, and the value that Arthritis and Rheumatism Associates places on the excellence of its clinicians, Aidan was eager to return to begin his career.

Aidan is passionate about improving the quality of life of his patients and assisting them in managing their pain and achieving the highest level of function possible. He employs a variety of manual treatment techniques, neuromuscular re-education, therapeutic exercise, and patient education in the care of his patients to help them achieve their rehabilitation goals.

Outside of work, Aidan enjoys remaining active by weightlifting in the gym, playing ice hockey, and getting outside as much as possible. He is also an avid Washington Capitals fan and loves to attend games in D.C.

Nicholas (Nick) McGarry, PT, DPT

Nicholas (Nick) McGarry, PT, DPT

Nicholas (Nick) McGarry grew up in southeast Pennsylvania and spent an almost equal amount of time on the coast of New Jersey. He completed his undergraduate studies at the College of Charleston in Charleston, SC, where he earned a Bachelor of Science in Exercise Science. He subsequently achieved his Doctor of Physical Therapy degree at Methodist University in Fayetteville, NC. During his graduate-level clinical rotations, he gained significant experience in different clinical settings, including outpatient orthopedics, acute care, and inpatient rehabilitation. In his career as a licensed physical therapist before joining Arthritis and Rehabilitation Therapy Services, he gained extensive experience practicing in Pennsylvania and Virginia in various clinical environments, including SNIF, outpatient orthopedics, and sports and performance rehabilitation, which allowed him to hone his evaluative and clinical treatment skills in caring for patients with a wide variety of diagnoses and conditions and at different stages of the rehabilitation process.

Dr. McGarry’s diverse background and clinical experience provide him with the tools to effectively treat a variety of patient populations, including patients with chronic pain, and neurologic, neuromuscular, and orthopedic diagnoses. While providing skilled manual treatment and exercise instruction to improve mobility and mechanics, Nick’s treatment approach emphasizes patient education to empower patients to independently manage and improve their conditions and make long-term, sustainable changes. Nick effectively strives to break down complex diagnoses into their component parts to facilitate patient understanding and success in rehabilitation.

Outside of work, Nick enjoys spending time on the water, especially with friends and family.

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