Written by: Dr. Frederick Buechel, Jr.
What is Robotic Partial Knee Replacement Surgery?
A partial knee replacement/resurfacing surgery replaces the worn down cartilage surface of the knee joint bone with metal and plastic parts called “implants” that are cemented to the bone surfaces. This restores smooth painless motion, restores the natural tension to the ligaments and corrects the angular deformity of the leg. Partial knee replacement only resurfaces or replaces one or two of the 3 compartments of the knee joint and maintains the healthy compartments and ligaments, allowing more normal function and motion. The three compartments of the knee that can be replaces or resurfaced are the medial, lateral and patellofemoral compartments.
A Mako™ Robotic Partial Knee Replacement Surgery is a partial knee replacement performed with the a highly precise installation system. This system includes a software package that allows for precision pre-operative planning, functional intra-operative adjustment of the plan based on ligament gap optimization and implant tracking, and a true robotic arm bone cutting machine that is controlled by the surgeon, to prepare the bone for anatomically designed implants that are cemented to the bone surfaces.
This precision installation system when used properly allows for consistently, reproducible precision implant installations which has been shown to improve outcomes, satisfaction and reduce failure in the peer review literature and joint registries around the world. Prior to the Mako™ Partial Knee Replacement System introduction, the early failure rates of manual partial knee replacement surgery was 4-5 times greater, which is why most surgeons have traditionally recommended total knee replacement over partial knee replacement. However, now with Mako Partial Knee, the early 2 year failure rates that were published with Dr. Buechel’s patients are shown to be less than 1%, and the satisfaction rates are in the high 90% range, which is improved over total knee replacement.
What are the indications that someone may require Robotic Partial Knee Replacement Surgery?
It is not the robot that drives the indication, the robotic system allows for the precision surgery that increases the chances of a successful, optimally placed, partial knee replacement.
The history of a patient that can benefit from a robotic partial knee replacement includes:
- Weight-bearing knee pain that is confined to one compartment of the knee.
- The most common side of the knee that is replaced is the inner side, called the medial side.
- The second most common side is the outer side, called the lateral side.
- The third most common compartment to be replaced is the patellofemoral compartment, or the kneecap compartment.
- Pain in two of the 3 compartments of the knee with intact ligaments (ie. Medial & Patellofemoral compartments)
- When non-surgical treatments or minor surgical procedures no longer provide pain relief and a persons’ quality of life is reduced
- Younger active patients that want to remain very active
- Older patients that are too unhealthy to undergo the stress of a total knee replacement and its recovery
- Patients with a prior ACL reconstruction that has gone on to develop arthritis in the medial compartment.
- Patients that have failed some of the cartilage repairing operations on one side of their joint
The clinical diagnoses indicated for partial knee replacement are osteoarthritis, osteonecrosis, or a prior knee injury like a meniscus tear or prior fracture.
The x-ray findings that indicate for a partial knee replacement will show a decrease or total loss in the joint space in one or two of the compartments of the knee, and the other compartment or compartments have a preserved joint space between the bones.
Medial Compartment Osteoarthritis
Lateral Compartment Osteoarthritis
The physical exam findings indicated for partial knee replacement are:
- Pain on examination in the compartments that are worn down on X-ray
- No pain in the compartments that have preserved joint spaces.
- The ACL and PCL ligaments should be stable on exam.
- The collateral ligaments must be intact and have stable end points when corrective tension is applied to the knee on exam.
- Range of motion for best candidates should have no more than 15 degrees loss of extension and at least 90 degrees of flexion.
- Varus (bowlegged) deformities should be less that 15 to 20 degrees.
- Valgus (knock-kneed) deformities should be less than 10 degrees for optimal results.
Partial Knee Replacement vs. Total Knee Replacement
Dr. Buechel looks at each patient’s situation individually before deciding on partial knee replacement or total knee replacement. The preferred procedure for Dr. Buechel to perform is partial knee replacement if indicated by the criteria described in the two sections above. When looked at critically, probably 50% of patients or even more could benefit from partial knee replacement, instead of total knee replacement, in the hands of an experienced partial knee surgeon. This is why getting an opinion from a very experienced partial knee and total knee surgeon is important to truly know your options.
Most surgeons perform less than 10 partial knee replacements a year and will tend to recommend total knee for their patients, even if they could have a partial knee replacement because this is more comfortable for them. A well done total knee is a good fix, but a well done indicated partial knee feels better and more natural than a total knee. This is why having your knee evaluate by Dr. Buechel who has done more than 1,500 robotic partial knee replacement is beneficial.
Is a Robotic Partial Knee Replacement Surgery still considered knee replacement surgery?
Partial and total robotic knee replacements are both considered knee replacements. They both replace the surfaces of the bone where the cartilage has worn out with metal and plastic parts. Partial Knee Replacement can be much less invasive from an exposure standpoint if your surgeon is skilled at partial knee replacement and preserves the healthy functioning structures of the knee. Total knee replacement is more invasive and should therefore be used only when truly indicated.
Is there a difference between partial robotic knee surgery and resurfacing?
There are several terms that are used interchangeably to describe partial knee and total knee surgery. The synonymous names include knee replacement, knee resurfacing, and knee arthroplasty. The acronyms reflect these synonyms and include PKA and PKR.
Is this considered a virtual knee surgery?
Mako™ Robotic Partial & Total Knee Replacement is not virtual surgery like the well known DeVinci robotic surgery system where the surgeon sits at a console on the side of the operating room controlling the Robot above the patient. Mako Robotic Partial Knee Replacement System uses a CAT scan image to extremely accurately plan and customize the implant placement for each individual. The Mako Robotic Arm is held by the surgeon and the cutting tool at the end of the arm is guided by the surgeon across the bone surface, while the robot controls the boundaries of the cutting tool, preventing cutting outside the boundary.
What should I expect during my first appointment?
During the visit, you should:
- Dr. Buechel will go over your medical and knee history
- Dr. Buechel will perform a focused knee physical examination
- Dr. Buechel will review with your x-rays with you
- Any further imaging can be ordered if necessary during your visit.
What is the expected pain with a Robotic Partial Knee Replacement Surgery?
Robotic Partial Knee Replacement Surgery performed by Dr. Buechel is significantly less painful than when done by other knee surgeons using the Mako Robot for several reasons. A comprehensive pain control process has been developed by Dr. Buechel to make the procedure as comfortable as possible.
The first 2 days are generally very comfortable. Days 3 through 6 are the days that can be uncomfortable for some, as the blocks start to wear off, but not anything like total knee replacement pain. After the first week, most patients will not be taking any narcotic pain medication and ibuprofen and acetaminophen generally is all that is needed. Dr. Buechel’s pain control program includes all the following:
- He has developed several techniques using special instruments and a stabilizing leg holder that allows him to make a very small incision, put very little stretch on your skin and tissues, and still have great visibility to precisely install your implants with minimal tissue injury.
- He has his anesthesiologist provide you with a spinal anesthesia if possible and two blocks that give you great pain control after the surgery for 36 to 48 hours. He also places local anesthetic into the wound to provide you with even more pain control.
- He provides you with a knee cooling sleeve after surgery to reduce pain and swelling.
With this regimen, most patients only require ibuprofen and acetaminophen after surgery. Some patients will take a few low level narcotic pills for a few days the first week after surgery.
- A sports compression sleeve that Dr. Buechel will place on you in the office the day after surgery reduces swelling and pain.
- Elevation is part of his protocol, and along with the compression sleeve swelling is reduced which reduces pain.
- Dr. Buechel does not use a tourniquet which dramatically reduces pain after and during surgery, which allows for better bleeding control, reducing swelling and pain after surgery.
- The anesthesia team uses Dexamethasone IV steroid to reduce swelling after surgery and provide some increased pain controland avoiding aggressive physical therapy early in the first week allows the wound to seal and swelling to reduce.
- The pain is easily controlled with over the counter medication, the cold therapy sleeve, and sometimes one or two pain pills for a couple of days.
What is the normal recovery time for Robotic Partial Knee Replacement Surgery?
Recovery for a Medial Compartment Robotic Partial Knee Replacement surgery (the most common partial knee) is significantly less difficult than patients expect. The mild to moderate pain is generally limited to the first week. Swelling control is the main goal in the first 2 to 3 weeks. Once the swelling has resolved, the range of motion generally returns to the pre-op motion. Most patients by 6 weeks have all their pre-op motion back. By 3-6 months, many patients have increased their motion by 8-10 degrees.
Physical therapy for robotic partial knee replacement surgery is not an aggressive painful process like most total knee replacement therapy can be. I start with simple patient home exercises the first week to allow for wound stabilization and swelling reduction. Then I begin formal physical therapy the second week focused on improving the quadriceps strength and proper return of a normal, or near-normal gait cycle. Stationary bike exercise can begin right away using the non-operative leg only, to get your cardiac conditioning going and release the good endorphins into your system. At the end of the second week you can use both legs on the bicycle once the swelling has subsided and the wound has stabilized. Walking full weight bearing begins day one. You will start off with a cane, crutches or walker. You can eliminate any or all of these devices once you feel stable and confident with your balance. This is generally within the first week. But there is no rush, I want you to feel safe and use these devices until you feel ready to discontinue them.
Driving is generally okay by the end of the first week for most patients with the understanding that you are not allowed to drive ever if you are taking narcotic pain medication.
My Lateral compartment patients often have a similar recovery to the medial side partial knee patients, but sometimes it takes 4-6 months for the patients to feel as good on the lateral side as the medial compartment patients do at 3 months.
I limit high impact exercises like jumping or running, and high torque twisting like a strong golf swing and singles tennis until the 8 week mark, to allow the bone to stabilize where the tracking pins were inserted during your surgery, to reduce the risk of a bone fracture at the pin sites.
Patellofemoral compartment partial knee replacement patients take longer than the Medial and Lateral compartment robotic partial knee replacement surgery patients to recover. Because the patellofemoral incision involves entering into the quadriceps muscle or tendon, there is more post-operative soreness and stiffness than the other partial knee replacements. Therapy is also more aggressive to get the range of motion and strength to return. This is still less difficult than a total knee recovery.
What is the follow up care like for a Robotic Partial Knee Replacement Surgery?
Patients return to the office the day after surgery to have their dressing changed, to have their knee sleeve applied, to review their post-operative x-rays and to address any issues right away. Patients can return home if they are traveling to New York for their surgery generally in 1-2 days if needed. We maintain close contact with you in the early recovery phase to make sure you feel comfortable and all your concerns are addressed. We like to see you back if possible, in 4-6 weeks after surgery, or check in via any of our contact means along with photos of your leg during the healing process. 6 months after surgery is another check-in milestone we like to hear from you. Annually we like to have a check-in and x-rays of the operative knee to ensure everything is as desired.
When shouldn’t a Robotic Partial Knee Replacement Surgery be performed?
There are reasons that patients should not have a partial knee replacement. For some of these patients, a robotic total knee replacement can be an option.
- Inflammatory arthritis such as rheumatoid arthritis is not a good indication for partial knee replacement because the entire joint lining is involved in this disease process, not just one or two compartments. This is a good indication for total knee replacement.
- If the entire knee joint hurts on exam, this is not a good indication for partial knee replacement, this is an indication for total knee replacement.
- If the knee deformity (angle of the knee) is too severe, generally more that 15-20 degrees
- If the knee has poor motion with less than 80 degrees of flexion (bending), and flexion contracture (it won’t straighten) more than 15-20 degrees
- If the knee is too loose in extension. The knee hyper-extends more than 10 degrees on exam
- Having an ACL tear that is unstable on physical exam. Some ACL tears that are chronic are stable on exam and can still have a medial partial knee replacement without reconstructing the ACL
- Having a prior joint infection is a contraindication to a joint replacement and runs the risk of becoming infected again after the joint replacement surgery.
Select Relevant Publications
Buechel F., Buechel F., Conditt M. (2016) Robotic-Arm Assisted Unicompartmental Knee Arthroplasty (MAKO). In: Scuderi G., Tria A. (eds) Minimally Invasive Surgery in Orthopedics. Springer, Cham. Link to Article
Buechel FF Sr, Buechel FF Jr, Pappas MJ, Dalessio J. Twenty-year evaluation of the New Jersey LCS Rotating Platform Knee Replacement. The journal of knee surgery. 2002 Spring;15(2):84-9. Link to Article
Buechel, Frederick F. Sr. MD; Buechel, Frederick F. Jr. MD; Pappas, Michael J. PhD; D'Alessio, Jerry MS. Twenty-Year Evaluation of Meniscal Bearing and Rotating Platform Knee Replacements. Clinical Orthopaedics and Related Research. July 2001 - Volume 388 - Issue - pp 41-50. Link to Article