Darwin Chen, MD

Frequently Asked Questions

General Questions
The patient comes first! We take great pride in assuring that our patients have the highest quality medical care and outstanding surgical outcomes. Our office is highly responsive and centered around the patient experience.

Our practice takes a wide range of insurances. Please call the office at (212) 241-1924 for the most up to date information.
While the practice is geared towards hip and knee replacement surgery, we still see many patients for non-operative hip and knee care. This can include medications, physical therapy, and joint injections (cortisone, viscosupplementation, PRP).
Many, but not all, patients with end stage hip and knee arthritis are candidates for hip and knee replacement surgery. This website (hipknee.aahks.org) from the American Association of Hip and Knee Surgeons is a helpful guide.
We see patients in three locations.

Mount Sinai Faculty Practice Associates  (FPA) – 5 East 98th Street, New York, NY 10029

Mount Sinai Center for Advanced Medicine (CAM) – 17 East 102nd Street, New York, NY 10029

Mount Sinai North Shore Medical Group (NSMG) – 325 Park Avenue, Huntington, NY 11743

All surgical procedures and the postoperative hospital stay are at Mount Sinai’s Main Campus on the Upper East Side. Mount Sinai East is a world class hospital and is on the US News Best Hospitals Honor Roll.
If you have a life threatening illness or medical emergency, call 911 or go to your nearest emergency room. If you have an urgent issue, please call the direct office line – (212) 241-1924. After regular business hours, there is an answering service that goes directly to a physician on call.
Questions Regarding Surgery
When it is safe and technically feasible, Dr. Chen employs the least invasive surgical technique to perform your surgery. Dr. Chen is an expert in MIS joint replacement and rapid rehabilitation protocols. Not every patient is a candidate, however the vast majority of patients are.
Dr. Chen uses both the anterior and posterior approaches to perform hip replacement. Both approaches can be done using a minimally invasive technique. He is highly experienced in both approaches and is considered an expert on this topic. Dr. Chen believes both approaches have benefits and drawbacks, and he typically decides which approach to use based on what will give the patient the best possible clinical outcome with the least risk of complications. A variety of patient factors are considered, such as activity level, body habitus, and individual patient anatomy.  Most routine, primary (first-time) hip replacements are done through an anterior approach. Most revision and complex hip surgeries are done through a posterior approach.
Yes. Dr. Chen has done numerous hip and partial knee replacements on an outpatient basis. Patients have surgery in the morning, walk in the hospital with physical therapy in the afternoon, and are home for dinnertime. He was the first to perform outpatient hip replacement at Mount Sinai and has developed specific protocols to make this possible. Dr. Chen does outpatient surgery selectively, based on overall health, motivation, and home support systems.
For the vast majority of cases, we use spinal anesthesia with sedation. Studies have shown this is the safest and most effective way to perform anesthesia for total joint replacement. For knee surgery, we typically add a femoral nerve or adductor canal block. For both hip and knee surgery, we do a “periarticular injection” of long acting local anesthetics and pain medications before closure.
We close the incisions in a very similar, cosmetically appealing fashion as plastic surgeons do. The sutures are all underneath the skin and absorbable, and the skin is sealed with a special surgical skin glue. On occasion, we will add a few staples if the skin is very thin, the surgery was a revision, or if there are medical comorbidities (smoking, diabetes, obesity).
Dr. Chen is the primary surgeon and takes great responsibility for all his patients. In addition, there is typically a physician’s assistant (PA) and an orthopaedic surgery resident involved in the surgery. While Mount Sinai is a teaching institution and there are trainees present, Dr. Chen is 100% hands-on and the product of the surgery is his own.
With the current surgical and anesthetic techniques, the risk of needing a blood transfusion during or after surgery is less than 5%. Dr. Chen uses tranexamic acid (TXA) during all cases which has significantly reduced blood loss. For these reasons, autologous blood donation is unnecessary.
Dr. Chen uses a wide variety of hip and knee implants from many different orthopaedic companies. Dr. Chen fully believes in choosing the “right” implant for the patient based on activity level, age, and anatomy. Dr. Chen uses custom implants as well in select cases, both patient specific instrumentation (PSI) as well as implants that are custom made specifically for individual patients.
Dr. Chen’s complication rate for hip and knee replacement surgery is extremely low at < 0.5-1.o% and significantly below the New York State  and National average.
Most patients stay two nights in the hospital, although many will stay just one. Some patients are candidate for outpatient joint replacement. The vast majority of patients are discharged home with home services (visiting nurse and physical therapy)
Dr. Chen main practice focus is hip and knee replacement surgery, however he is well trained in open hip preservation surgery techniques such as surgical hip dislocation and Ganz periacetabular osteotomy (PAO). Dr. Chen does not perform hip arthroscopy.

Dr. Chen uses Mako robotic technology to perform the majority of his partial knee replacements and some total knee replacements. A common misperception is that the robot does the actual surgery, but this is not accurate. The robotic technique involves creating a three dimensional model of a patient’s knee from a CT scan. A preoperative plan is then created to provide optimal implant positioning and ligamentous balance. The robotic arm assists the surgeon in bone preparation, provides safety measures to protect the soft tissues around the knee, and is 100% controlled by the surgeon during the procedure.

Postoperative Care Questions
You are allowed to walk as much and as far as you feel comfortable. You can wean off of the assistive device (walker or cane)  as tolerated, as you gain more confidence in walking. The physical therapist (home or outpatient) will guide you in specific exercises to maximize recovery.  Most patients experience leg swelling and minor bruising. This is normal and expected. This is easily treated with ice, elevation, compression stockings, and rest.
Right away. You will be discharged with a waterproof dressing that will stay on for one week. Once the dressing is removed at one week, the incision may be left open to air and can still be showered on. No baths or pools are allowed on the incision until 4-6 weeks postoperatively.
The typical discharge medications are aspirin (blood thinner), oxycontin ER (long acting narcotic), oxycodone (short acting narcotic), Celebrex or Mobic (anti-inflammatory), Lyrica or neurontin (nerve pain medication),  and senna/colace (stool softener).
Call the office directly at (212) 241-1924. We will get back to you ASAP for any postoperative concerns. If it is after hours or the weekend, a medical answering service will deliver messages to the on-call physician.
Recovery is a very individual process. The majority of patients will use a cane for 2-4 weeks, although many are able to walk device-free in as little as 1-2 weeks.  75% of the recovery occurs within the first 2-3 months, and most patients are back to full activity at this time. It can take 6 months to 1 year however to reach the final outcome.
Dr. Chen allows patients to drive at 2 weeks postoperatively as long as they are not taking narcotic medications.

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