Dr. Mirzayan is one of the most experienced cartilage restoration surgeons in the United States, having performed over 350 cartilage transplantation procedures in the knee, shoulder, and elbow. When cartilage is damaged or missing, the joint loses its natural cushioning — leading to pain, swelling, and eventually arthritis. Rather than accepting a metal or plastic joint replacement, many patients are candidates for a biological solution using fresh donor cartilage to restore the natural joint surface. Dr. Mirzayan specializes in both simple and complex cartilage transplantation, including his innovative BioPFJ™ technique — a procedure specifically designed to restore the patella (knee cap) and trochlea (groove), the most technically challenging area of the knee. BioPFJ™ allows active patients to return to the sports and activities they love, with their own natural joint intact.
BioPFJ™ — Biologic Patellofemoral Joint Reconstruction A Revolutionary Alternative to Knee Replacement for Kneecap Arthritis
Were You Told You Need a Knee Replacement for Your Kneecap? There Is Another Option.
Patients with arthritis or cartilage damage of the patellofemoral joint — the kneecap and its groove — are routinely told they need a metal and plastic joint replacement. For a 25-year-old athlete who has dislocated their kneecap repeatedly, or a 45-year-old who wants to stay active, that is a devastating recommendation. A traditional replacement means permanent activity restrictions, a finite lifespan of the implant, and the certainty of revision surgery down the road.
Dr. Raffy Mirzayan invented a different solution: BioPFJ™ — a complete biological reconstruction of the patellofemoral joint using fresh donor tissue, restoring the joint with real cartilage instead of metal and plastic. Patients return to running, cycling, hiking, and sports. One patient even went on to run several marathons after this procedure!
Dr. Mirzayan has performed this procedure in approximately 75 patients — more than any other surgeon in the world — No metal. No plastic. No permanent activity restrictions.
To find out if you are a candidate, call (310) 746-5918 or request a consultation online. Virtual consultations are available for patients traveling from Las Vegas, Henderson, Phoenix, Scottsdale, or anywhere from the world.
Understanding the Problem: The Patellofemoral Joint
The patellofemoral joint is formed by two structures: the patella (kneecap) and the trochlea (the groove at the bottom of the thigh bone where the kneecap glides). This joint is uniquely challenging because of the extreme forces it absorbs — every time you climb stairs, squat, or run, the patellofemoral joint bears forces several times your body weight.
When the cartilage of this joint is damaged or destroyed, the result is deep, aching kneecap pain, swelling, grinding, and eventually the inability to perform basic daily activities. Two very different groups of patients develop this condition:
Young patients with recurrent patellar instability Some patients — typically in their teens and 20s — are born with a shallow or malformed trochlear groove (trochlear dysplasia). This causes the kneecap to repeatedly dislocate or slide out of place. Each dislocation damages the cartilage further. By the time many of these patients are evaluated, their kneecap and groove cartilage is severely damaged — at an age when a traditional knee replacement is simply not an acceptable option. These patients are typically told to "manage" their symptoms, or offered complex reconstructive procedures that don't address the underlying cartilage loss.
Active middle-aged patients with isolated patellofemoral arthritis A second group — typically in their 40s and 50s — develops isolated arthritis specifically in the patellofemoral joint, while the rest of the knee remains healthy. Traditional total knee replacement sacrifices the entire joint to fix one compartment. A patellofemoral replacement uses metal and plastic components that restrict high-impact activity. Neither option is ideal for an active patient who wants to return to sport.
For both groups, Dr. Mirzayan's BioPFJ™ procedure offers what no other treatment can: a complete biological reconstruction using real human cartilage from a carefully matched donor.
The Invention: What Is BioPFJ™?
BioPFJ™ stands for Biologic Patellofemoral Joint reconstruction. It is a procedure Dr. Mirzayan developed and pioneered involving the simultaneous transplantation of fresh osteochondral allograft tissue to both the patella and the trochlea — replacing the entire patellofemoral joint surface with living biological tissue from a single matched donor.
Here is what makes it revolutionary:
The patella (kneecap) component: The damaged cartilage surface of the patient's kneecap is carefully removed using a precision saw, preserving the underlying bone. A fresh donor kneecap — carefully matched in size and shape — is prepared and its cartilage side is secured directly onto the patient's remaining patellar bone using three compression screws. The result is a perfectly shaped, living cartilage surface where metal and plastic used to be the only option.
The trochlea (groove) component: The damaged groove of the patient is simultaneously replaced with the trochlear graft from the same donor. Because both grafts come from the same donor, the articular surfaces are perfectly congruent (mtaching)— the kneecap and groove fit together exactly as nature intended, in a way that no metal or plastic implant can replicate.
Why the same donor matters: This is the critical insight that sets BioPFJ™ apart from every other cartilage restoration technique. Traditional osteochondral allograft procedures to the patellofemoral joint have historically had higher failure rates, in part because mismatched donor surfaces create incongruent articulation. By using the same donor for both the patella and the trochlea, Dr. Mirzayan ensures a perfectly matched biological joint — the same geometry, the same curvature, the same cartilage thickness.
In patients with trochlear dysplasia (a shallow, malformed groove), the donor trochlea also corrects the underlying anatomical abnormality — something that no other procedure achieves while simultaneously addressing the cartilage damage.
Why This Is Revolutionary
Even surgeons who regularly perform osteochondral allograft transplantations across the knee consider patellofemoral joint reconstruction one of the most technically demanding procedures in cartilage surgery. The complex three-dimensional geometry of the kneecap and groove makes sizing, preparation, and fixation extraordinarily challenging. Most cartilage surgeons do not offer this procedure at all.
Dr. Mirzayan has spent years mastering and refining this technique. With approximately 75 cases performed — far more than any other surgeon in the world — he has established a level of experience with BioPFJ™ that simply does not exist anywhere else.
The outcomes have been extraordinary:
- 100% graft integration of the patella— the donor kneecap has healed to the patient's remaining patellar bone in every single case, a result that was not expected given concerns about blood supply to the patella
- No revisions or conversions to arthroplasty in the published series
- Dramatic improvements across every functional outcome measure — KOOS, IKDC, Tegner-Lysholm, Oxford, Cincinnati, VAS pain, and SANE scores all improved significantly (P < 0.0001)
- Patients returned to high-level athletics — including a marathon runner, a college basketball player
- No recurrent patellar dislocations in any patient treated for instability
Published Evidence
Dr. Mirzayan published the first outcomes study of bipolar osteochondral allograft transplantation of the patella and trochlea in the peer-reviewed journal Cartilage (2018). The study — the largest cohort of bipolar patellofemoral allograft patients in the scientific literature at the time — demonstrated significant improvement across all functional outcome scores with 100% graft survival. This was also the first report of osteochondral allograft transplantation being used to address trochlear dysplasia.
His series has since grown to approximately 75 patients with continued outstanding results.
Who Is a Candidate?
Group 1 — Young patients with recurrent patellar instability and cartilage damage:
- Typically teens to early 30s
- History of multiple kneecap dislocations
- Documented trochlear dysplasia (shallow or malformed groove)
- Cartilage damage to the kneecap and/or groove from repeated dislocations
- Failed or inadequate response to prior stabilization procedures
Group 2 — Active patients with isolated patellofemoral arthritis:
- Typically 40s to mid-50s
- Isolated arthritis of the kneecap compartment with a healthy remainder of the knee
- Unwilling to accept the activity restrictions of a traditional joint replacement
- Desire to return to an active lifestyle including sports and athletics
What to Expect
- Surgery type: Open surgical procedure performed under general anesthesia — outpatient
- Non-weightbearing: 4 weeks following surgery to protect the healing grafts
- Range of motion: Immediate — continuous passive motion initiated from day one without restriction in the range of motion
- Strengthening: Begins as soon as possible with progressive return to activity
- Full recovery: Typically 6–9 months to return to high-demand athletic activity
- Results: significant improvements in functional outcome measures. Dramatic improvement in pain and function. Patients have returned to running, cycling, tennis, and marathon running.
Frequently Asked Questions
What does BioPFJ™ stand for?
BioPFJ™ stands for Biologic Patellofemoral Joint reconstruction — a complete biological resurfacing of the kneecap and groove using fresh donor tissue.
Is this a knee replacement?
No. BioPFJ™ uses no metal or plastic components. The entire joint surface is reconstructed with living biological tissue from a human donor. There are no permanent activity restrictions, and there is no implant that will wear out over time.
Why does the same donor matter?
The kneecap and groove must fit together perfectly. Because both grafts come from the same donor, the articular surfaces are naturally congruent (matching) — matched in geometry, curvature, and cartilage thickness. This is a critical advantage over procedures using mismatched grafts from different donors.
How many of these procedures has Dr. Mirzayan performed?
Approximately 75 — more than any other surgeon in the world. His published series in the journal Cartilage (2018) was the largest bipolar patellofemoral allograft study in the scientific literature at the time of publication.
What are the outcomes?
Every patient in Dr. Mirzayan's series has achieved 100% graft integration of the donor kneecap has healed successfully to the patient's remaining patellar bone in every single case. No patient has required revision or conversion to a traditional joint replacement. Patients have returned to marathon running, cycling, tennis, and other high-demand sports.
I was told I need a kneecap replacement. Am I a candidate for BioPFJ™ instead?
Possibly. Dr. Mirzayan evaluates each patient individually. If your arthritis is isolated to the patellofemoral compartment and the rest of your knee is healthy, BioPFJ™ may be an option. Virtual consultations are available. Call (310) 746-5918.
Do you see patients from outside Los Angeles?
Yes. Dr. Mirzayan welcomes patients from Las Vegas, Henderson, Phoenix, Scottsdale, and from all over the world. Virtual consultations are available for out-of-state patients. Call (310) 746-5918.
Is this covered by insurance?
Osteochondral allograft transplantation is typically covered by insurance. However, Dr. Mirzayan is an out-of-network surgeon. Many patients have excellent out-of-network benefits for procedures such as BioPFJ™ at costs equivalent to in-network care. His team will help you understand your coverage before surgery.
