What is a partial knee replacement?
The knee has three main areas, called compartments: the inner side, the outer side, and the area behind the kneecap. Arthritis sometimes wears out only one of them, most often the inner side.
A partial knee replacement, also called a unicompartmental knee replacement, resurfaces only the worn area with metal and plastic parts. The healthy cartilage and the ligaments in the rest of the knee stay in place. Dr. Pareek performs partial knee replacement with robotic assistance.
Am I a candidate for a partial knee replacement?
You may be a candidate if your pain sits in one part of the knee, X-rays show arthritis mostly in that area, and non-surgical care has stopped helping. Surgeons usually also look for:
- A stable knee with working ligaments, including the ACL
- Good knee motion before surgery
- Healthy cartilage in the other compartments
- No inflammatory arthritis, such as rheumatoid arthritis
Pain that is spread across the whole knee, or arthritis in more than one area, usually points away from a partial replacement. Standing X-rays and your exam guide the decision.
For younger, active people with less advanced damage, it may also make sense to discuss cartilage restoration and osteotomy.
How does a partial replacement compare with a total replacement?
The most useful evidence is the TOPKAT trial, which randomly assigned 528 people with arthritis on the inner side of the knee to a partial or total replacement. Their average age was 65. Surgeons in the trial had expertise in the operations they performed.
At 10 years, both operations gave good results, and the study ruled out any meaningful difference in knee scores. Complications occurred in 21% with partial replacement and 29% with total replacement. Further operations occurred in 8% and 10%. Revision to a new implant occurred in 5% of each group (Beard, 2026).
So neither operation wins outright. A partial replacement fits only a knee with arthritis limited to one area, and a total replacement treats the whole joint. Your exam, imaging, and goals decide which is reasonable.
What does robotic assistance do?
The robot does not operate by itself. Your surgeon makes the plan and does the surgery. Before or during the operation, the system maps your knee so the implant size and position can be planned. During the operation, it helps guide the bone preparation toward that plan.
The goal is accuracy. Partial replacement leaves less room for error, because the implant works alongside your own ligaments and cartilage.
Is robotic partial knee replacement better?
It depends on what you measure.
Accuracy. In a randomized trial of 107 patients, robotic surgery matched the planned implant position more accurately than a conventional approach (Kayani, 2026).
Early recovery. The same trial found lower pain scores in the hospital, less opioid use, and a shorter hospital stay with robotic surgery (Kayani, 2026).
Function. At two years, three standard knee scores showed no difference. A fourth score, which measures how much you notice your knee, favored robotic surgery. These were interim results, and recruitment slowed during the trial (Kayani, 2026).
Revision. A review of 34 studies and 68,196 partial replacements found lower complication and revision rates with robotic surgery. Operations took about 16 minutes longer. The authors said robotic surgery may offer benefit, but they warned that the studies varied widely, and that it is unclear whether the differences in function matter to patients (Kanakala, 2026).
So there are real signals in favor of robotic assistance, but the evidence does not prove that it gives a better long-term knee for every person.
Can I return to sport after a partial knee replacement?
Many people can. A review of 749 patients found that 48.1% had returned to sport at three months and 76.5% at six months, and 92.7% were able to return by four years. Most of those who returned played at a lower intensity than before surgery (Radhakrishnan, 2022).
What are the risks of surgery?
Risks include infection, blood clots, stiffness, ongoing pain, loosening or wear of the implant, and arthritis progressing in another part of the knee. Some people later need a revision surgery or conversion to a total replacement. Results vary from person to person, and no surgeon can promise a certain outcome.
Should I get a second opinion?
It can help, especially if you were told you need a total replacement and want to know if a partial is an option, or the reverse. Here’s how a second opinion works.
Where can I see Dr. Pareek?
Dr. Pareek sees patients for partial knee replacement at HSS in New York and at HSS in New Jersey. Bring any X-rays, MRI images, and reports you already have.
What does recovery look like?
These are typical ranges. Your surgeon’s plan comes first, and recovery varies from person to person.
- Weeks 0-2: Walk and protectMany people walk with a walker or cane soon after surgery and go home the same or next day. Early work focuses on swelling, pain, and wound care.
- Weeks 2-6: Regain motionPhysical therapy works on bending and straightening the knee. Most people use a cane less as walking improves.
- Weeks 6-12: Build strengthTherapy moves toward thigh and hip strength, balance, and stairs. Many people return to daily routines in this stretch.
- Months 3-6: Return to activityLower-impact activities such as cycling, swimming, and golf come back in steps, as your knee allows.
- Months 6 and beyond: Settle inStrength and comfort can keep improving for many months. These are typical ranges, and your surgeon's plan governs.
Sources
- Beard DJ, et al. Assessing clinical and cost effectiveness of total versus partial knee replacement (TOPKAT): 10-year follow-up of a multicentre, randomised controlled trial. Lancet Rheumatol 2026;8:e116-e126.
- Kayani B, et al. A prospective double-blinded randomized controlled trial comparing conventional jig-based versus robotic arm-assisted medial unicompartmental knee arthroplasty. Bone Joint J 2026;108-B:1113-1120.
- Kanakala S, et al. Robotic assisted versus manual unicompartmental knee arthroplasty: a systematic review and meta-analysis. Orthop Surg 2026. doi:10.1111/os.70424.
- Radhakrishnan GT, et al. Return to sport after unicompartmental knee arthroplasty: a systematic review and meta-analysis. Orthop J Sports Med 2022;10:23259671221079285.