Patellofemoral Knee Replacement
Dr. Garcia’s technique for a patellofemoral replacement
Testimonial after PFJ, TTO and MQTFL 2025
Expert Surgical Management of Isolated Patellofemoral Arthritis
Background
Patellofemoral replacement (PFR), also known as patellofemoral arthroplasty, is a surgical procedure designed to treat arthritis confined to the patellofemoral joint-the articulation between the kneecap (patella) and the groove at the end of the femur (trochlea). Unlike total knee replacement (TKR), which resurfaces the entire knee, PFR selectively addresses wear and damage limited to this compartment, preserving the unaffected medial and lateral compartments of the knee.
Patients with isolated patellofemoral arthritis are often younger and more active than those with tricompartmental arthritis, and PFR can offer quicker recovery, greater range of motion, and higher functional scores when appropriately indicated.
Patellofemoral Replacement Testimonial in Young Active Female
Indications
Ideal candidates for patellofemoral replacement include:
- Symptomatic anterior knee pain localized to the front of the knee, typically worse with stairs, squatting, or prolonged sitting (“theater sign”).
- Advanced patellofemoral osteoarthritis confirmed on imaging, often with bone-on-bone wear.
- Failure of non-operative treatments such as physical therapy, activity modification, bracing, NSAIDs, and intra-articular injections.
- Preservation of the tibiofemoral compartments (medial and lateral) with minimal or no degenerative changes.
Common causes of isolated patellofemoral arthritis include:
- Primary degenerative arthritis of the patellofemoral joint.
- Dysplasia or maltracking of the patella leading to uneven cartilage loading.
- Prior trauma, such as patellar fractures or recurrent instability.
- Post-surgical changes, especially after procedures like lateral release, MPFL reconstruction, or realignment osteotomies.
Contraindications to PFR include generalized osteoarthritis involving all compartments, inflammatory arthritis, fixed varus or valgus deformity, or significant ligamentous instability.
iBalance® Patellofemoral Joint Arthroplasty
Imaging
Accurate diagnosis and surgical planning rely on a combination of clinical evaluation and imaging. Typical imaging studies include:
X-rays:
- AP (anterior-posterior), lateral, and sunrise/Merchant views to evaluate the severity of joint space narrowing, patellar tilt or subluxation, and trochlear morphology.
- Standing long-leg alignment films to assess overall limb alignment.
MRI:
- Useful in younger patients or those with early-stage disease to assess articular cartilage status and rule out meniscal or ligamentous pathology.
- Helpful in identifying subchondral edema, dysplasia, and early tibiofemoral degeneration.
CT Scan:
- Occasionally employed for preoperative planning, especially in cases with significant malalignment or rotational deformity.
Imaging should confirm isolated patellofemoral degeneration with preservation of the medial and lateral compartments.
Check out my recent patient testimonial after patellofemoral replacement.
Surgical Options
The two main surgical approaches for patellofemoral arthritis are:
- Total Knee Arthroplasty (TKA): This resurfaces all compartments but is often considered excessive for patients with isolated disease and intact tibiofemoral joints.
- Patellofemoral Replacement (PFR): This compartment-specific procedure targets only the diseased articulation, preserving normal knee anatomy, native cruciate ligaments, and bone stock.
The goal of PFR is to remove arthritic cartilage from the trochlea and the undersurface of the patella, replacing them with prosthetic components. This targeted approach can yield better functional outcomes and quicker recovery in the right patient.
Surgical Technique
Patellofemoral replacement is performed under regional or general anesthesia and typically takes 60–90 minutes.
Approach:
- A standard medial parapatellar approach is most common, although midvastus or subvastus approaches may be used depending on surgeon preference.
- Careful dissection is required to maintain extensor mechanism integrity and visualize the patellofemoral articulation.
Patellar Component:
- The patella is sized, and the undersurface is resected to accommodate a polyethylene button.
- It is crucial to maintain the proper patellar thickness to avoid overstuffing or instability.
Trochlear Component:
- The femoral trochlea is resected using patient-specific or standard cutting guides.
- The metallic trochlear component is implanted, ensuring alignment with the native trochlear groove to optimize patellar tracking.
Trialing:
- Component sizing and positioning are confirmed through trial implants.
- Patellar tracking is assessed through range of motion to ensure smooth articulation without tilting or maltracking.
Final Fixation:
- Components are cemented into place.
- Wound closure is performed in layers, and local anesthesia is often used for postoperative pain control.
The entire knee is evaluated for smooth patellofemoral articulation, range of motion, and ligamentous balance before concluding the procedure.
Check out Dr. Garcia’s recent webinar on patellofemoral replacements and cutting-edge advances
Complications
As with any surgical procedure, PFR carries risks, although complication rates are generally lower than with TKA in properly selected patients.
Common complications include:
- Persistent anterior knee pain: Often related to improper component alignment, overstuffing, or patellar maltracking.
- Progression of tibiofemoral arthritis: In 10–20% of cases, necessitating conversion to total knee arthroplasty.
- Malalignment or maltracking of the patella.
- Infection or wound complications.
- Component loosening or wear over time.
- Stiffness or limited range of motion.
Careful patient selection, surgical precision, and rehabilitation help mitigate these risks.
Dr. Garcia demonstrates a custom patellofemoral replacement
Recovery
Recovery from patellofemoral replacement is typically faster and less painful than total knee replacement, with many patients returning to activities earlier.
Hospital Stay:
- Often performed as an outpatient or with a 1-night hospital stay.
- Early mobilization is encouraged, often on the day of surgery.
Weight-Bearing:
- Patients are allowed to bear weight as tolerated immediately after surgery with assistive devices as needed.
Physical Therapy:
- Begins within a few days postoperatively and focuses on:
- Regaining range of motion (especially flexion).
- Strengthening the quadriceps.
- Improving gait mechanics.
- Most patients complete therapy in 6–12 weeks.
Return to Activities:
- Driving: 2–3 weeks post-op for the non-dominant leg; 4–6 weeks for the dominant leg.
- Office work: 2–4 weeks.
- Light athletic activity (cycling, golf, swimming): 6–8 weeks.
- High-impact sports are discouraged to protect the implant.
Outcomes
Patellofemoral arthroplasty has shown excellent outcomes in appropriately selected patients, with high satisfaction rates and improved function.
Video testimonial after patellofemoral replacement with a cartilage transplant
Clinical Outcomes:
- Studies report 85–90% success rates at 5–10 years post-op in patients with isolated disease.
- Improvements in validated outcome scores such as KOOS, WOMAC, and Oxford Knee Score.
- Patients often report improved stair climbing, reduced anterior knee pain, and increased activity levels.
Longevity:
- Survivorship at 10 years ranges from 75–90%, depending on implant design and patient activity.
- Some patients may ultimately require conversion to total knee arthroplasty if arthritis progresses in other compartments.
Conversion to TKA:
- PFR does not preclude future total knee arthroplasty.
- Conversion is generally straightforward and carries comparable outcomes to primary TKA in most series.
Modern implant designs and improved surgical technique have greatly enhanced the reliability of PFR. Cemented, fixed-bearing components with anatomic trochlear geometry have reduced maltracking and improved long-term function.
Summary
Patellofemoral replacement offers a minimally invasive, joint-preserving solution for patients with isolated patellofemoral arthritis. When performed on the right candidate, it can significantly reduce pain, restore function, and maintain native knee biomechanics. As an orthopedic surgeon, I recommend a thorough evaluation and imaging workup to determine candidacy, followed by a personalized treatment plan that may include patellofemoral arthroplasty.
If you’re experiencing anterior knee pain that hasn’t responded to conservative treatment, and imaging confirms isolated degeneration, a patellofemoral replacement may offer the relief and return to activity you’ve been seeking.
