Doctor Tarlow on Knees

Minimally Invasive Surgery (MIS): Who is a Candidate for MIS Total Knee Replacement

2008-05-18T06:37:00.004-06:00

Here in the Phoenix - Scottsdale, Arizona area I am frequently asked by patients "Can you perform Minimally Invasive (MIS) Total Knee Replacement (TKR) on my knee ?."

My answer is I can perform Minimally Invasive Total Knee Replacement on most any patient but I choose to use the technique on the large subset of patients that benefit most from the technique. It is a surgical procedure that is more technically demanding and more time consuming than traditional Total Knee Replacement so I am somewhat selective on choosing patients for this method. By analogy, I would not buy a new Basketball for my 90 year old mother in law but I would for my teenage son who is on the high school basketball team. She would never use the basketball and he would use it frequently.

I always perform Minimally Invasive Surgery on the healthy, motivated, energetic patients who will recover fast because of their good health and motivation to get well fast. I rarely perform Minimally Invasive Surgery on unhealthy patients with multiple co morbidities (Diabetes combined with cardiac or respiratory disease combined with high Body Mass Index is a typical patient profile that comes to mind). The first example patient would take full advantage of having had this technique by discharging from the hospital in 1-2 days, be walking freely without a walker in 5-10 days, be driving in 10 days -3 weeks, be back to work in 2-4 weeks and be golfing or hiking in the beautiful Arizona desert in 4-8 weeks. The second example patient would recover but take 1-3 months to reach similar milestones.

Body mass index is sometimes a factor since some patients with high BMI have low energy. BMI alone is not a reason not to perform MIS Total Knee surgery.

A normal BMI is under 30 and defined as a six foot tall man weighing 215 pounds or less or a five foot six inch woman weighing 182 pounds or less.
Obesity (BMI 30-40) is the six foot man between 215 and 285 pounds or the five foot six woman between 182 and 240 pounds. Morbid obesity (BMI above 40) is above 285 pounds for the six foot man and above 240 pounds for the five foot six inch woman. (BMI tables are available online to calculate your own BMI). Minimally Invasive Surgery can be performed on the higher BMI patients. It always requires a skin incision 2-4 times longer than the incision in under 30 BMI patients. The longer skin incision allows the surgeon to "convert" the high BMI patient into a low BMI patient by retracting away the "extra" skin and subcutaneous tissue. However, the definition of Minimally Invasive Surgery Knee Replacement and the key factor allowing for faster recovery is not the size of the skin incision but the size of the deep or Capsular incision that allows the surgeon into the knee joint proper. Therefore high BMI patient can have Minimally Invasive Total Knee Replacement Surgery and enjoy the benefits of a faster recovery.

Returning to the question posed at the beginning of this post: Who is a candidate for Minimally Invasive Total Knee Replacement Surgery ? The answer is that most people are good candidates for MIS TKR as long as they are healthy, have a good energy level and are motivated to recover quickly.

National Standards to Rank Physicians Planned

2008-04-01T22:12:00.003-06:00

This recent article on a National Standard to Rank Physicans caught my attention. The political backdrop is fairly complex (and rancorous) but it drives at an important issue for patients: how do you pick a good doctor?

I would welcome a new system if its valid, reproducible, and accurate. It would be fantastic for patients to have that meaningful information to rely on when picking a doctor to treat a new illness or condition...informed choice.

How will I be rated? Surgical skill, patient management, outcomes, bedside manner? For the system to succeed, it needs to be flexible enough to go across specialties. The skills sets of a great anesthesiologist are much different than the qualities you need from orthopedic surgeon.

As an orthopedic surgion, i think the most important factors is judgement/ decision making. Do you know when to try one thing before the next, when surgery is necessary, etc. It's not just brain power. (Jerome Groopman discusses this at length his book "How Doctors Think", a great read for patients and physicians alike). The next most important trait is surgical skill. Again, I would welcome a system that could accurately, and reproducibly evaluate these important factors.

What factors do you use to rate your doctors? How do you go about finding a good one?

Otis Med: Shape Matching Custom Fit Total Knee Replacement

2008-02-24T11:23:00.002-07:00

There is a movement under foot that runs counter current to the time tested principles used to position the implants in Total Knee Replacement. This principle is called Shape Matched Technology (this phrase is a trademark of Otis Med). It allows for what Otis Med terms a custom fit Total Knee Replacement.

Here is an excerpt from the Otis Med site (http://www.otismed.com) :

Shape-Match™ Technology

OtisKnee™ is based on OtisMed’s patent pending, proprietary Shape-Match™ technology. Using sophisticated 3-D software, the Shape-Match™ technique optimizes the size and placement of the Custom Fit Knee™ before surgery, based on the patient’s own normal (non-arthritic) knee anatomy. From this very precise 3-D image, custom cutting guides are created to assist the surgeon in making very accurate bone cuts that are specific to the individual patient. This allows for a “customized” implant fit and placement. Prior to the availability of Shape-Match™ technology, surgeons have relied on experience and intra-operative judgment to correctly size and place the implant in the patient. END of OTIS MED excerpt.

In essence Otis Med uses MRI images of the diseased arthritic knee. The proprietary software then calculates how much of the joint surface has been lost in the arthritic knee, calculates how much to "put back" to restore the knee to it's normal, naturally given position and then provides the surgeon with custom made tools to restore the knee "back to normal". A key principle in the Otis Med technique is to restore the axis of rotation to the knee, and this can only be done by identifying the normal axis of rotation on the reconstructed MRI scans. This information is then provided to the surgeon by fabricating custom cutting blocks that are used to re sect the bone when performing an OtisKnee. This can not be accomplished with traditional Total Knee Replacement in the same manner as OtisMed, even if the surgeon uses Surgical Computer Navigation. Otis Med technique can only be used with Stryker and Biomet implants (because of the shape specific to these two brands of implants).

The debate, which is just heating up and should be spirited, will compare the merits of the totally new concept of precisely how to position the knee implants using the Otis concept, to the traditional technique of making every replaced knee straight (mechanically aligned to match a straight line running from the hip to the center of the ankle) and balancing the knee ligaments by releasing contracted ligaments and tightening stretched knee ligaments.

As I begin to analyze this radically new way to position knee implants I must say I am somewhat intrigued by the OtisMed rhetoric. Their concept places critical importance on the balance and range of motion of the knee, with axial alignment secondary (almost an after thought). Traditional technique stresses axial alignment above all else, with balance by ligament release important as well. Traditional technique, which here to for has been the dogma for positioning implants, boasts long term results with 90 % success rates 10-20 years after implantation. There are only a few peer review published articles supporting the Otis Med concept.

As they say, the jury is still out on the Otis Med principle. As a surgeon living in an ever changing, high technology world I believe I owe it to my patients, myself and my profession to study the facts for and against the Otis Med technique. Ultimately I will make an informed decision based on the best information available as whether or not to incorporate this technique into my practice of Knee Surgery.

Replacing Knees Sooner in Women May Enhance Outcome

2007-11-18T11:50:00.000-07:00

Conventional Orthopedic Surgical wisdom is to delay joint replacement until the patient is seriously impaired by their symptoms, even though on x-ray the patient's knee joint is destroyed by arthritis. This means delaying surgery for serious knee arthritis until patients can not walk more than a block or two, can only ascend and descend stairs one at a time, patients are limping and patients have sleep disturbance from arthritis pain. Additionally, conventional wisdom recommends trials of NSAIDS (ibuprofen like meds), physical therapy, bracing, steroid injections or Hyaluronic Acid injections (synvisc and the like).

The lead article in the November, 2007 Journal of Bone and Joint surgery challenges this precept and presents strong scientific evidence to support the conclusion to operate sooner on women with serious knee arthritis that have measured functional deficits. The article is entitled Disease-Specific Gender Differences Among Total Knee Arthroplasty Candidates and was done at the University of Delaware.

Arthritis of the knee has a greater effect on knee function and strength in women, reflecting a gender difference in the disease impact. This larger impact on knee function in women is manifest by lower quadriceps muscle strength ( large muscle group in the front of the thigh), longer timed up and go standing test, longer timed stair climb, and shorter 6 minute walk distance compared to men with knee arthritis.

The logical and yet revolutionary conclusion is that strength and functional decline should be closely monitored (this functional testing could be documented by a Physical Therapist) in women with knee arthritis and when worsening is observed, joint replacement should be carried out. In some cases this may mean joint replacement is done sooner (compared to using traditional standards for deciding on the timing of surgery) .

Minimally Invasive Total Knee Replacement Facilitates Recovery

2007-09-09T19:19:00.000-06:00

An article appeared in the July, 2007 Journal of Bone and Joint Surgery entitled "Minimally Invasive Total Knee Arthroplasty Compared With Traditional Total Knee Arthroplasty". The main author is Seth S. Leupold, M.D. from the Department of Orthopedic Surgery at the University of Washington in Seattle.

The conclusion of the article is that minimally invasive Total Knee Replacement seems to facilitate recovery after this operative procedure. The patients who had the minimally invasive approach demonstrated significantly better clinical outcomes with respect to shorter length of hospital stay, higher percentage of patients discharged to home instead of inpatient rehabilitation facility, less narcotic use at 2 and 6 weeks post operatively and less need for assistive devices to walk at two weeks after surgery.

The Journal of Bone and Joint Surgery is one of the most respected and credible orthopedic surgery publications. The journal was founded in 1903 and is the official journal of the American Association of Orthopedic Surgery. The guiding principle of the JBJS is excellence through peer review. There are high standards, professional review and rigid criteria that have to be met before an article is accepted for publication. This is one of the first unbiased articles to appear in a prestigious orthopedic journal confirming the benefits of minimally invasive Total Knee Replacement. Therefore I believe the appearance of this article in the JBJS is highly significant.

Like the author of this article, I began performing MIS Total Knee Replacement in 2004. And just as the author discusses in the quoted article there is a learning curve of at least 25 cases to become more familiar with the technique. Like the author I perform a number of these operations on a monthly basis so that I got the over the learning process in a 3 month period. Over the last 3 years I have performed Minimally Invasive Knee Replacement on most of the patients I treat surgically for knee arthritis.

The components that are implanted are the same for MIS and Traditional Knee Replacement. I always use Surgical Computer Navigation as I believe this improves the accuracy in component position.

In my experience 1 in 4 patients are discharged home after one night in the hospital and most of the remaining patients go home after 2 nights. It is less common for a patient to be hospitalized 3 nights or to be discharged to an inpatient rehab facility. Similarly 25 % of patients are walking without assist in a week and the 70 % are walking without assist at 2 weeks. Most patients are driving in 2-3 weeks.

The results with respect to mobility, knee motion, pain relief and function for activities of daily life after MIS and Traditional Knee Replacement seem to merge around 3-12 months after surgery, however the return of quadriceps strength seems to occur sooner in MIS patients.

In conclusion I found the publication of the article highly significant and supportive of the beliefs of my colleagues who are currently performing minimally invasive Knee Replacement. Surgeons using minimally invasive techniques for Joint Replacement do so because of the greater patient benefits with this procedure.

Airport Metal Detectors and Orthopedic Implants

2007-05-28T07:54:00.000-06:00

In my practice patients will ask whether their orthopedic implant will cause any trouble at an airport security checkpoint. Until now I had not been able to reference any scientific studies that have evaluated which implants would trigger the airport metal detector.

An article that recently caught my attention was titled "Detection of Orthopaedic Implants in Vivo by Enhanced-Sensitivity, Walk-Through Metal Detectors" and appeared in the April, 2007 Journal of Bone and Joint Surgery. This article will be of general interest to patients in predicting whether their implant will trigger extra scrutiny at a security checkpoint. Shown on the right is an xray of a stainless steel plate and screws at the knee joint. This is likely to be detected by the Airport Metal Detector because of the large size of the blade plate and screws.

Patients with Total Hip and Total Knee replacements are commonly given credit card sized identification cards to travel with. However, in reality these cards are not acknowledged by airport screeners. If you have an orthopedic implant in your body that is likely to trigger the Airport Metal Detector allow extra time (5-15 minutes) to pass through airport security. What my patients with Knee Replacements tell me is that their implant does trigger the detector, and they are taken to the secondary screening station. There they are "wand ed" to verify the cause of the Metal Detector alarm was in fact their artificial knee and then they are cleared through the screening area. Rarely is any other type of more prolonged and time consuming screening done.

In their study the authors looked at Hip replacements, Knee replacements, spine fusion hardware, and upper and lower extremity fracture repair rods, plates and screws and wire.

Xray of Total Hip Replacement (above). This has a 100% chance of triggering the Airport Metal Detector.

The findings are summarized here. As you read the findings keep in mind that detection rates will vary because of the following facts: 1. Different brands and models of detector machines will have variable detections rates. 2. Sensitivities of metal detectors can be influenced by local magnetic interference such as fluorescent lighting or from other medical imaging devices. Repeating this study in a different location, such as your hometown airport, may show different detection rates. However in general the following observations can guide you as to the likelihood of whether your orthopedic implant will trigger an airport metal detector.

Total Hip replacements were detected 100% of the time.
Total Knee replacements were detected 90% of the time.
Total Shoulder and wrist replacements were not detected.
Plates with screws were detected approximately 25% of the time.
Screws alone or wire alone or intramedullary rods alone were usually not detected.
Lower extremity implants were detected 66 % of the time.
Upper extremity implants were detected 17% of the time.
Spine implants were detected 14% of the time.

And the type of metal matters. Cobalt chrome and titanium were likely to be detected, while stainless steel was unlikely to be detected.

Photograph of Knee Replacement implants made of cobalt chrome (above). Total Knee Replacements are detected 90% of the time by Airport Metal Detectors.

I invited readers to submit their experiences navigating through security with orthopedic implants.

Carticel: Replacing Damaged Knee Joints with Biologic Tissue

2007-04-15T14:19:00.000-06:00

It has been over a month since my last post, so I thought that after such a long delay I should create a blockbuster post. The photos alone should mesmerize orthopedic blog readers.

Occasionally as orthopedic surgeons, we are challenged to find a biologic treatment for young patients whom either through disease (osteochondritis dissecans is the most common) or through trauma are left with large (greater than 2x 2 centimeter defects) full thickness articular cartilage defects in the knee (femur) that are best treated by the Carticel procedure (Genzyme Biosurgical). These defects are too large to be treated by micro fracture or OATS procedures.

This treatment requires a minimum of two operative procedures. Surgery number one is an arthroscopy of the knee at which time two or three "tic tac" sized pieces of articular cartilage are harvested from a perimeter, unimportant part of the knee joint. Sometimes concomitant with this arthroscopy other procedures are done (bone grafting or osteotomy, but I will not go into this as it complicates this discussion).

The patient's articular cartilage cells are sent overnight in a refrigerated package to Genzyme Biosurgical. The cells can be stored for 5 years. When the patient is ready for the second procedure to implant the cells, Genzyme is notified. The cells are then grown in culture until millions of cells have be produced. The patients own cells are then placed in 1-3 vials and sent overnight to the hospital to be implanted.

Surgery number two is an open knee operation in which: 1. the articular cartilage (joint surface) lesion is trimmed to a circular or oval shape 2. A periosteal patch(cellophane like tissue covering bone) is harvested from the tibia, cut to size and sewn into place over the articular defect with very fine (about the diameter of human hair) absorbable sutures 3. The periosteal patch is sealed with tissue glue, tested to confirm there are no leaks and then the patients own cells which are in a semi liquid form are injected under the patch into the defect and a final suture and tissue glue is applied.

After the second operation the patient is hospitalized a night or two. These patients have a very regimented post operative rehabilitation protocol and limited activities for 6-12 months while the cells heal and replace the damaged joint surface with new cells that are similar to the cells nature initially produced. However, after healing is complete they can return to activities, with or without limitations depending on the overall health of the knee, the number and size of the defects.

This procedure is limited to patients aged 15 to 45 (maybe 50) and can not be used to treat osteoarthritis.

Enjoy the photos. Photo one: articular lesion trimmed and ready for the periosteal patch. Photo two: periosteal patch sewn into place. Photo three: Patients own cells in place under the patch sealed with tissue glue. This is a lesion of the medial femoral condyle and the underlying disease is osteochondritis dissecans.

Partial knee replacement - Medial Uni

2007-03-05T21:54:00.000-07:00

This is an xray of a partial knee replacement. Specifically, this is a medial unicompartmental knee replacement. This fifty something year old man had pain localized to the medial aspect of his right and left knees. Carefully look at this xray and note that the lateral compartments (outside of each knee) has a well maintained joint space while the medial compartment of the untreated knee has bone on bone. The treated knee has a femoral component cemented into the femur(thigh bone), a tibial component cemented to the tibia (shin bone), and a ultra high molecular weight polyethylene component (xray invisible space) which is locked into the tibial tray. This procedure has provided the patient complete relief of his symptoms of knee arthritis. He went on to have his left knee partially replaced in the exact same manner and now functions normally without knee pain. He has returned to work and feels good. He was hospitalized only overnight in the hospital and was riding an exercycle within 10 days after surgery.

Partial knee replacement - Patellofemoral Replacement

2007-03-05T21:42:00.000-07:00

This is an xray of a partial knee replacement. The specific type of partial knee replacement is a " patellofemoral arthroplasty" or replacement of the knee cap and the femoral groove in which the knee cap tracks. The knee on the right has been surgically corrected, including the centering of the knee cap on the femoral groove. I prefer to use Computer Surgical Navigation when performing this operation which results in a more accurate placement of the components in the knee which results in better function of the knee and a longer lasting partial knee replacement (up to 20 years). The knee on the left is severely arthritic and is malpositioned. The malpositioning or lateral tracking of the patella, along with recurrent patellar dislocations, caused this patient's knee caps to wear out prematurely.

Partial Knee Replacements

2007-02-25T19:54:00.000-07:00

Usually, osteoarthritis of the Knee involves the entire joint, and a Total Knee Replacement is the treatment of choice. Perhaps one in ten people with knee osteoarthritis with severe enough involvement of the joint to consider surgery are fortunate enough to have the arthritis limited to only one compartment of the knee. In this case partial knee replacement is the best surgical choice. The knee has 3 compartments (think of the knee as a 3 room home). When just one compartment has all the articular cartilage or joint surface damaged (one bad room, two good room) partial knee replacement is done. This is also known as unicompartmental knee replacement (uni) if the medial or lateral compartment between the femur and tibia (thigh and shin bone) is replaced or patellofemoral replacement if the joint between the femur and patella (thigh and knee cap bone) is replaced.

Unicompartmental knee replacements function better than total knee replacements because less of the normal anatomy is disturbed ( no knee ligaments removed, less bone removed) and the uni knee bends, straightens and rotates more naturally. Recover after unicompartmental knee replacement is quicker and the postoperative pain is less compared to total knee replacement.

Longevity of a unicompartmental knee is very good, with nine in ten uni's working well at 10 years after surgery and many functioning well 20 years after surgery. The most common cause of failure after uni knee replacement is advancing arthritis in one or both of the previously uninvolved compartments of the knee.

Here is an excerpt of an article in the Arizona Republic about one of my patients in whom I performed partial knee replacement in one knee, then 3 months later the other knee. This is an example of how well partial knee replacements function. Outcomes like this is why I wanted to practice medicine. The link to the full article is at the bottom of this post.

"After suffering for years with knee damage that limited her mobility, Sarah Panepinto does not take dancing with her husband or playing tag with her kids for granted.

Last year, the 41-year-old Gilbert mother of five children had partial knee-replacement surgery on both of her knees. Since then, Panepinto said her recovery has been a miracle.

I can dance. I'm speed-walking. And I can even play Dance, Dance, Revolution with my kids," Panepinto said.

The more active lifestyle is a blessing for Panepinto who needs the energy to keep up with the home-schooling of her two teens and two elementary school-age kids.

I'm off anti-depressants . . . I feel like I have my life back," said Panepinto who has suffered from knee problems since she was 12."

Read the full article

Knee Pain and Bicycling

2007-02-25T00:49:00.000-07:00

Many of my patients turn to the Internet before and after their visit to the clinic to research their symptoms, find medical advice, and learn exercise that may provide relief. This didn't happen 20 years ago when I started my practice.

Occasionally, I am asked to recommend Internet resources. Today I came across the Gatorade Sports Science Library. This site features articles and rountable discussions by physical therapist and sport medicine physicians. It's worth a visit.

In my sports medicine practice, I see a couple patients per week who experience knee pain when cycling. As a mountain biker and cyclist myself, I found this article about knee pain after cycling rides informative. The article makes the point that simple seat adjustments, altering your biking stroke, and strengthening exercises can provide considerable relief for some people.

Knee Osteoarthritis and Exercise Walking

2007-02-05T23:00:00.000-07:00

People who do about 6 to 9 miles a week of recreational walking don't appear to be at greater risk for osteoarthritis of the knee than their more sedentary peers, according to a study appearing in the February issue of Arthritis Care & Research. This article appeared in the Los Angeles Times on February 5, 2007. Based on the results, researchers concluded that even overweight participants — who have an increased risk of developing osteoarthritis — are not more likely to develop the disease as a result of exercise.

The findings should ease concerns among those considering taking up an exercise program.

It is Dr. Tarlow's opinion that the development of knee osteoarthritis is multifactorial. Genetics and family history play an important role. Another strong risk factor for developing osteoarthritis of the knee is a previous serious knee injury such as tearing an ACL ( anterior cruciate ligament) or tearing of the medial meniscus.

The First Post

2007-01-28T22:23:00.000-07:00

My 25 year old son suggested I start sharing information with my patients and prospective patients here on this blog. I agreed and here we go. My lot in life professionally is to help people by practicing Orthopedic Surgery. I specialize in treating injuries and diseases of the knee. No case is too difficult, yet the routine is rewarding as well. There is a supreme satisfaction that is inherent in the practice of medicine - helping your fellow human being. This is a common theme that attracts people to the practice of medicine.

The more common problems treated by a knee surgeon includes treating knee arthritis (with a combination of medicines, physical therapy, knee injections, arthroscopy and Knee Replacement surgery and Partial Knee Replacement surgery), knee ligament injuries including ACL (anterior cruciate ligament), meniscal tears with knee arthroscopy, knee pain with physical therapy and more advanced biological treatments to regrow the articular cartilage in the knee ( Carticel or OATS procedure). When the knee arthritis is advanced and knee replacement is advised, I am a strong proponent of MIS (minimally invasive surgery) coupled with computer navigation guidance. There is no better process to replace a knee because of the faster recovery time, less pain, quicker return to a normal life and with computer navigation, complete and precise placement of the components. I have a heading on my bio page on my practice web site (www.southwestsportsmedicine.com) which reads "What really moves me is seeing how fast my patients can recover". This phrase summarizes exactly the benefits of MIS joint replacement.

Finally for today, I hope to receive e-mail questions from readers of the blog and I will chose relevant questions and post the questions and answers on this blog. Contact me at doctlow@gmail.com.