Dr. David Chang, MD, Orthopedic Surgeon

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ContributorDr. David Chang, MD, Orthopedic SurgeonRead Full Bio


Dr. David Chang is a board certified orthopedic spine surgeon who specializes in surgical treatment of spinal disorders. He has worked and studied in both coasts of the country. After graduating from Princeton University, he received his medical degree from New York University. He completed his orthopedic surgical training at NYU-Hospital for Joint Diseases. He completed an advanced fellowship in orthopedic spinal surgery with Drs. Robert Watkins and Lytton Williams. With his training under Dr. Watkins, Dr. Chang understands the complexities of sports related spinal injuries. Additionally, Dr. Chang’s interest lies in minimally invasive spinal surgery, artificial disc replacement technology and degenerative disorders of the cervical and lumbar spine. Dr. Chang is part of the Watkins Spine Group that works in association with the Marina Del Rey Hospital in the Southern California area.

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ContributorDr. Robert G. Watkins IV, MD, Orthopedic SurgeonRead Full Bio


Robert Watkins IV, M.D., is co-director of Marina Spine Center and Chairman of the Surgery Department at Marina Del Rey Hospital. Dr. Watkins is a board-certified orthopedic spine surgeon, specializing in minimally invasive spine surgery, computer-assisted surgery, spinal-deformity treatment, and disc replacement. Dr. Watkins earned his medical degree at the University of Southern California’s Keck School of Medicine and completed his residency in orthopedic surgery at the L.A. County/USC General Hospital. He then worked as a traveling fellow in Europe, specializing in artificial-disc replacement and scoliosis surgery. Over the past decade, he has lectured on spine issues to doctors, patient groups, athletic trainers, and physical therapists; led research teams that have published studies; and taught surgeons on specialized techniques. He is the spine consultant to many Los Angeles sports teams, and has treated professional, college, and high school athletes from all over the country.

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I'm Dr. David Chang, um, a board certified orthopedic surgeon. I went to school at Princeton University for undergraduate education then I went to NYU School of Medicine. After that I did a five-year orthopedic residency at the NYU School of Medicine and Hospital for Joint Diseases. Then I did a Spine Fellowship with Dr. Watkins out here in Los Angeles. Back pain is multifactorial in ideology. I mean obviously there's gonna be some anatomic structures that could be the epicenter of that back pain. Could it be the disc, could it be the facet joints, could it be nerve issues, could be just muscular aches. But, what leads to it? Is it going to be psychosocial factors? Just stresses, emotional stresses from job, emotional stresses from your family life. Is it going to be real physical work be it working around the house or your physical job, labor-type job.

So, those are some of the things that just kind of come to my head, whenever I'm examining patients. What are the other things that might be affecting the patient as it relates to back pain? So this is the model of the spine and it's pretty life size. I talk about the spine as a multisegmented structure not much different than a centipede if you will, a lot of repetitive parts. People always refer to the disc, it's one of the largest structures here that we might be able to see but I refer to the spine in motion segments. So let's take this segment here, and then this would be the L5 bone, L4 bone, L3 bone, L2 bone, and L1 bone. L stands for lumbar.

And if we take this motion segment at L2-3, it comprises the L-2 bone and the L-3 bone as well as an intervening disc, which would be the L2-3 disc. If we say a singular number, it's usually referring to a bone or a singular nerve root if we say L2-3 it's usually referring to the motion segment, the disc segment, or the structures back here that my fingers are pointing to those are the facet joints. And, you might be able to see one bone rub and articulate with the bone below at that joint. Coming back to that motion segment concept, there's two bones, one disc, and two adjacent facet joints.

And in that motion segment, there's usually gonna be two nerves that could be potentially irritated. There's gonna be 15 joints in the spine. Five disc joints and then two paired facet joints so that's 10 joints and any one of those can break down, and once one breaks down, then that starts putting abnormal stresses on the other . So we'll talk about degenerative disc disease. And I think that is a, for a lack of better term, dump truck category or term that encompasses many spectrums of degeneration within the disc or the spinal motion segments. The disc is a shock absorber, think of it as a sponge. Maybe the disc is drying out, right? Maybe there's just small tears within the disc, we call them annular tears and that's on the mild side.

Then somewhere in the middle, there are disc herniations, or disc bulges. They're clearly disruptions within the disc, more than just mild dehydration. And then, on the right side of the spectrum, there's real frank degeneration in the disc, where the disc material is really dehydrated, it's starting to crack and fissure, maybe the disc space is collapsing. I think people often hear herniated disc or a bulging disc or disc protrusion, for the non spine specialist, they sort of blend together.

Clearly, disc herniations and disc bulges are going to be disruptions of the disc material. Some element of that disc material is going to be sticking out beyond the normal boundaries of that disc or that circle. If it's sticking out beyond the normal boundaries, it might be compressing some of these nerve roots that are passing by or traversing that specific disc. For a disc herniation, for me, it's very specific. It's sort of like crab meat, it's firm but soft. It's not as firm or hard as bone material but it is harder than the more pliable nerve structures.

So if that crab meat-like structure, or disc material is pushing on the nerve, it's gonna physically win that battle and compress that nerve and irritate that nerve. So a disc herniation is when you've got that crab meat-like material extruded out beyond the normal boundaries of the disc and it's pushing on a specific nerve root and oftentime what manifests from there is the radiating leg pain. Patients might refer to it as sciatica type pain. The disc bulge, again, still a disruption to the disc.

I liken it to a situation where if you took a small dough ball and you just started compressing it, well it's gonna start pancaking out in sort of a horizontal plane, sort of non specifically and sort of generically, very broad based and when I see a disc bulge on an MRI, clearly I'll see a structural change in the shape of the disc material. Maybe I'll see a little bit of nerve compression, but it seems somewhat symmetric right versus left. I reserve that sort of structural and clinical picture for a disc protrusion or a disc bulge or a bulging disc.

Other terms you might hear are slipped disc, and the disc is not actually slipped but it's unstable to the extent that in that concept of the motion segment where you have one bone, one disc and another bone below it, the top bone is slipped forward relative to the bone below and medically that's called a spondylolisthesis. If you look at it from a side profile, the back edge of each one of these bones has to flow nicely in a smooth, curved line, right? But in a model where there is a slipped disc, this bone is gonna be slipped forward and so the back edge of this bone, if you can imagine, it would have sort of a staircase or a stepped off pattern to flow into the back edge of the bone below it.

So, when patients come into my office and they tell me what their chief complaint is, I want to know what's bothering them, how long has it been bothering them, and then beyond that, how is that affecting them. And I also ask them point blank, what do they expect from me? How do they envision me helping them? Oftentimes we'll get x-rays, that's the first test, it's a great test. It's a sort of a surveillance type exam, it'll show the bones of the spine, it'll show the alignment of the spine, it'll show sort of the curvature if patients have scoliosis. So, it's like looking at the forest from a distance.

Then there are other types of tests that are really trying to look at the branches and the leaves of those trees of the forest. The MRI allows us to actually look at the composition of that disc material, see if it's dehydrated or it's not dehydrated, see if there are actually any disc bulges or disc protrusions or disc herniations that might be pushing pressure on the nerves. We might be able to see other structures like cysts, that could also be coming from a facet joint that could be putting pressure on the nerve roots. CT scan as a modality is great to look at the bony st-architecture. I can talk about cracks in the bones or broken bones, it can highlight bone spurs coming off the facet joints or the disc joints.

There are other types of CT scans where in addition to the CT scan imaging you're also gonna do a myelogram. And a myelogram is gonna be what people think of as a spinal tap. A radiologist has to put a needle into your back and we'll inject some dye. That dye is a radiopaque dye which will be seen on the CT scan and the purpose of that is that dye is going to illuminate the nerves that wouldn't otherwise be seen, or readily seen on a CT scan.

Now we can see the nerves, juxtaposed to the bones with real good image quality. Oftentimes we're not using contrast imaging of an MRI or a CT scan unless maybe it's a revision case or a more complicated case we think there might be some tumor involved or something like that. There's one more test called the bone scan and the bone scan is not sort of the bone scan that primary medical doctors to evaluate for osteoporosis, this is a bone scan specifically called a SPECT scan and it stands for single photon emission computed tomography and it helps evaluate where the bone cells are going in your body.

And to just to kind of quick sort of overlay of it is we'll inject you with a very small amount of radioactive substance and it's just a marker and that marker will light up bone or tag and label bone cells. It's sort of like Lojack for a car, the car gets taken, gets going to another place and we're able to find out where it goes. And so similarly with the SPECT scan, your brain's gonna tell those bone cells to go someplace, maybe they're gonna go to a degenerated hot joint, maybe the facet joint, maybe the disc joint. And if the bone scan picks up on that we'll have a bright red spot or a hot spot at that one particular joint level and that helps us, as spine surgeons narrow down where your pain generator is.

And if that bone scan or SPECT scan comes back positive then that leads up to recommend surgery with a little more certainty and it raises our probability that surgery's actually gonna help you in the context of that particular disc causing your pain and maybe doing a fusion surgery to address it. A microdiscectomy, we're gonna break that word apart, ectomy means remove, and we're going to remove some of the disc. We're not gonna remove all of the disc material. Oftentimes a microdiscectomy is used to treat a disc herniation and we're only gonna remove a small fragment of that disc, maybe five percent of that disc material.

It's a relatively quick procedure in the world of spine surgery it's sort of the equivalent to an arthroscopic procedure although it's not technically arthroscopic. I use the term micro because we're using a very small incision and we're using a microscope. And a microdiscectomy is utilized to treat a disc herniation. And so this is a model of the spine and your back skin would be here and we're gonna make a small, two-centimeter incision for a one level procedure, slide the muscle tissue over to the side, and get access to the space where the disc herniation is and on this model, let's say it's here. This is a far lateral disc herniation and this is a unique type of disc herniation, usually their more rotated into the spinal canal region.

Once we get to this space, we're gonna have to shave a little bit of bone and that's technically called a laminotomy. We shave a little bit of the bone and we take a ligament that's overlying that area that you don't see here and we'll take that away. And once we have that opened up, then it's safer to get access to that disc herniation that's being compressed by the nerve. Sort of thinking about it, if you got a big disc herniation here, a big ball of tissue, and you got a tiny little hole and you're trying to work through that tiny little hole to pull all that material away sometimes that's hard to do and specifically when there's a pliable nerve there, a sensitive nerve, that could be traumatic to the nerve. In essence, we're making the hole bigger to make the surgery easier but also safer for the nerve that's getting compressed.

Once we take that disc material away we then just let the muscle fall back, close up the wound and it's all done. Takes maybe about an hour oftentimes we can do it as an outpatient procedure these days, come in in the morning and you can leave by the afternoon. For this type of procedure, the anesthetic time is relatively short so you don't often get a catheter into your bladder. But for longer procedures, maybe a two or three level discectomy or maybe a two or three level laminectomy you will get a catheter.

Immediately after the surgery, often patients don't complain of too much back pain but clearly sometimes we're working around the back and it can be painful. And it's hard to predict who's gonna have more back pain than the next patient who's not gonna have back pain. But generally we want patients to stand up immediately after the surgery and they're up and they're walking and if they had they red hot searing sciatica type pain, after the microdiscectomy patients are able to sort of cut through the chaff of the back pain and notice that their searing sciatica pain is gone.

You're gonna be able to go home after you meet a couple of measures. You gotta be able to walk, your pain's gotta be under control, you gotta be able to-to urinate on your own, and you gotta be able to keep food down not being nauseated and vomiting. If you meet those four end points by my standards, you can go home. Getting on to laminectomy, ectomy mean remove and we're gonna remove lamina. And the lamina is specifically this sheet of bone that blends into the spinous process. There's lamina on the right side and there's lamina on the left side. And there are different forms of laminectomy. There's partial laminectomies all the way up to total laminectomies.

And that refers to how much of this bone are you removing. And a total laminectomy we would remove all of this bone so that you could then see all of the yellow structures in this model which would be the nerves. Oftentimes when we're doing a laminectomy we might do more than just one level and oftentimes the laminectomy's gonna be performed on an maybe older patient who has multilevel degenerative problems and we're gonna do two, three, four level, so it's a longer procedure and there's more anesthetic time maybe more soreness. Oftentimes, besides a catheter in your bladder there might be some drains in your back.

Those drains are just collecting any residual fluid, maybe a little bit of blood, mostly fluid. We want to stop any bleeding accumulating causing a blood clot or hematoma on those nerves. So, you might stay in the hospital one or two nights. Again, after surgery you're gonna be walking around albeit gingerly and then as your at home all I want you to do for the first couple days is to walk. We walk you to avoid the BLT's, bending, lifting, twisting. 'Cause the more bending, lifting, twisting that you do around your back, the more you're going to stir up the pot and irritate some already irritated muscles and it's just gonna drag out the healing process if you will.

It might create even more inflammation that winds up irritating the nerve that we just wound up decompressing. So, all I want you to walk maybe three, four times a day, the extent of the walks depends on the patients exercise tolerance and conditioning. You can go up and down stairs, you can get in and out of bed a walk up and down hills is okay but generally speaking I try to have patients walk on level ground and listen to your body. If you're walking x number of feet and it's beginning to hurt you, well you want to cut that down, maybe by half initially and then just slowly build yourself back up.

We're not gonna start formal physical therapy until basically the wound and the muscles settle down and that's gonna start around four to six weeks after surgery. Once we get into physical therapy formally we're gonna talk about core stabilization strengthening again. As it relates to driving, patients often ask when can they drive and that sort of dovetails into when can they go back to work. Usually after a microdiscectomy, I think up to two weeks after the surgery you could start driving, so long as your not on any narcotics and so long as you feel reasonably comfortable to drive.

Driving will clearly put more pressure on the disc and the joints and can cause pain in the back. Usually it doesn't amount to too much but sometimes I worry about recurrent disc herniations. I think after a microdiscectomy patients go back to work anywhere from two to six weeks after surgery. It just sort of depends on what your pain level is and what your job description is. The person who has the office type job, maybe the owner of the company they're able to go back to work maybe a week or two after the surgery. The patients who have a much more physical, demanding job, labor type job, police officers, firefighters, they're not going back to work until much later after they've done the physical therapy, gotten their core strength to a level three, if not better. And sometimes that lays out to six months maybe even 12 months.

We're not gonna start physical therapy formally until maybe four to six weeks, closer to six weeks after surgery. Again, it's gonna focus on core stabilization type exercises and then you'll get into returning to work along the time line of around six weeks maybe even up to 12 weeks depending on the extent of the laminectomy, how many levels we had to do. I think that spine surgery, this day and age has really turned the corner so to speak and I think there are gonna be new technologies in the future that make spine surgery even better.

Some patients complain of back pain, we don't have a great solution for those patients and we'll be the first to admit we can't recommend surgery for that patient. But I think education is very important, I always talk about the anatomy of the spine and I think hopefully sometimes it doesn't fall on deaf ears so if a patient could bring in a caregiver when they come to their initial visits or any and all visits, I think it's always helpful to have two sets of ears hearing what I'm saying as opposed to just one set ears. I'm always available to answer questions and I think the questions only helps the patient understand what's going on with their back and ultimately is gonna help my eventual treatment maybe with surgery, maybe without surgery and their ultimate outcome. I think a better informed patient is going to be a better healing patient.

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