Staged Patellofemoral Arthroplasty for Bilateral Knee Pain

    A 74-year-old woman presents with bilateral anterior knee pain. She has significant pain when going up or down stairs, kneeling, squatting, and standing from a seated position. Because non-operative treatment has failed to provide relief, the authors recommend patellofemoral arthroplasty.


    Julie Shaner, MD, and Jess H. Lonner, MD


    Julie Shaner, MD, has no disclosures relevant to this article. Jess Lonner, MD has the following relationships to disclose: Zimmer, Blue Belt Technologies, CD Diagnostics, Healthpoint Capital, Wolters Kluwer Health, Lippincott Williams & Wilkins, Saunders/Mosby-Elsevier, American Journal of Orthopedics, Journal of Arthroplasty, The Knee Society.

    Case Presentation

    A 74-year-old female was referred to the authors’ practice with a history of bilateral anterior knee pain. She said she had little to no pain when walking on level ground, but had significant pain when going up or down the stairs, kneeling, squatting, and standing up from a seated position. She denied paresthesias.

    Previous treatments included cortisone and viscosupplementation injections, various non-steroidal anti-inflammatory drugs, bracing, and physical therapy, all without substantial or sustained relief.

    Physical Examination

    • Height: 5 feet, 2 inches; weight: 124 pounds
    • No limb length discrepancy
    • Neutral alignment with a normal Q angle and negative J sign
    • Good quadriceps strength
    • Knee motion: Right 0-120°; left 5-120°
    • Bilateral anterior knee pain and crepitus with ROM
    • Pain with patellar compression; positive patellar inhibition
    • No medial or lateral joint line tenderness
    • Sensation intact to light touch in bilateral distal extremities
    • Palpable dorsalis pedis and posterior tibial pulses bilaterally

    Differential Diagnosis

    • Patellofemoral arthritis
    • Knee bursitis/ Hoffa’s disease
    • Prepatellar bursitis
    • Plica synovialis syndrome
    • Patellofemoral instability/subluxation
    • Quadriceps tendonitis
    • Patellar tendonitis
    • Diffuse degenerative joint disease


    • Plain radiographs included standing anterior-posterior (A/P), mid-flexion posteroanterior (P/A), lateral. and Merchant views of each knee (Figure 1)    
    • Previous MRI of both knees confirmed advanced patellofemoral arthritis with preservation of the articular cartilage of the medial and lateral compartments

    Figure 1 a-b. The standing A/P view (a, left) shows an absence of tibio-femoral joint space narrowing, indicative of preserved tibio-femoral compartments. The standing P/A view (b, right) shows an absence of arthritic change of the medial and lateral compartments.

    Figure 1 c-d. The lateral views (c, left and center) show patella osteophyte formation. The Merchant views (d, right) show bilateral patellar tilt and lateral subluxation.


    • Bilateral patellofemoral arthritis


    • Scoliosis/chronic back pain
    • Breast cancer
    • Hypertension


    The patient agreed to a staged bilateral patellofemoral arthroplasty at 3-month intervals. We recommended staged procedures rather than bilateral simultaneous surgery to allow each procedure to be done on an outpatient basis and to minimize the surgical risk.

    We have previously written about the resurgence of patellofemoral arthroplasty for patients with isolated, non-inflammatory anterior compartment arthritis resulting in pain and functional limitations that are persistent despite reasonable attempts at non-operative treatments. [1]

    Advantages of Patellofemoral Arthroplasty vs. Total Knee Arthroplasty

    • Quicker recovery
    • Less postoperative pain
    • Less associated blood loss
    • Less-invasive approach and less bone and soft tissue resection
    • Decreased operative time
    • Shorter rehabilitation
    • More closely resembles native knee kinematics
    • More normal feel

    Disadvantages of Patellofemoral Arthroplasty vs. Total Knee Arthroplasty

    • Outcomes related to surgical technique and implant design (onlay vs. inlay)
    • Risk of progression of osteoarthritis.

    Advantages of Onlay vs. Inlay System

    • Less patellar maltracking, catching, and subluxation due to better accommodation to a wider variety of trochlear geometries
    • Implant extends more proximal than the articular margin of the trochlea so that the patellar component articulates entirely with the trochlear component
    • Maximizes coverage of prepared bone
    • Provides flush zones of transition where edges contact the femoral condyles


    • A short-acting spinal anesthetic is typically the preferred mode of anesthesia for this procedure. However, this patient has severe scoliosis and chronic lumbar back pain, and therefore, a peripheral saphenous nerve block was used in addition to general anesthesia administered by laryngeal mask airway.
    • The patient was positioned supine on the operating room table, with the operative extremity prepped and draped and placed in a foot holder.
    • The limb was exsanguinated and the tourniquet was inflated.
    • An anteromedial skin incision was made.
    • An arthrotomy was carried out through a medial parapatellar incision; alternative arthrotomies can be used at the surgeon’s discretion. When performing the arthrotomy, avoid inadvertently damaging the intact femoral condylar cartilage, the medial meniscus, or the intermeniscal ligament.
    • Following joint exposure, a portion of the infrapatellar fat pad was resected and the patella was subluxed laterally with the knee in flexion. Inspection of the undersurface of the patella and the trochlear demonstrated patellofemoral arthritis. 
    • The medial and lateral tibio-femoral compartments were inspected to rule out substantial chondromalacia, and the integrity of the cruciate ligaments was assessed.
    • The anteroposterior axis (Whiteside’s line) was marked.
    • The femoral canal was drilled and the intramedullary anterior femoral cutting guide was inserted and rotated about the central axis such that the cutting slot of the guide was positioned perpendicular to the Whiteside’s line.
    • An attachable boom was positioned directly on the anterior femoral surface and was positioned preferentially on the lateral peak to avoid notching of the femoral cortex. The boom can be posteriorized from there when possible to make the cut relatively flush with the anterior femoral cortex without compromising rotation.
    • A milling guide with dimensions that correspond to the trochlear implant size was selected and positioned so as to avoid overhang beyond the edges of the femoral condyles medially or laterally. Once the milling guide was secured, a milling burr was used to prepare the bone in the intercondylar region.
    • The trochlear implant template and drill guide were then placed. The template should be flush with, or recessed no more than 1-2 mm relative to, the adjacent articular cartilage of the femoral condyles. If either of the transitional edges of the template is prominent at this edge, the burr can be used to carefully remove more bone until the template is flush. The template was secured and the lug holes were drilled.
    • The trial trochlear implant was impacted into place.
    • Attention was then focused on the patella, which was measured before resection. 
    • The articular surface was resected parallel to the anterior patellar cortex to restore the original patellar thickness when applying the implant. This should not be done if it would result in overresection of the patella, which could increase the risk of fracture or avascular necrosis.
    • An appropriately sized drill guide was applied in a medialized position and the lug holes were drilled.
    • The bone of the lateral patellar facet, which is not covered by the patellar component, was excised to both optimize patellar tracking and remove a potential source of anterolateral bony impingement.
    • A patellar trial was placed and patellar tracking was assessed. If maltracking is noted, confirm appropriate component placement. Next, consider performing a lateral retinacular release or recession. In cases of severe preoperative patellar maltracking, a proximal or distal realignment may be necessary.
    • Once tracking was optimized, the final components were cemented into place.
    • Excess cement was removed, analgesics were injected periarticularly, the joint was thoroughly irrigated, and the capsule and skin were closed.

    Postoperative Care

    Immediate Postop Period

    • The patient tolerated the procedure well without complications and was discharged to home on the day of surgery.
    • She was weight-bearing as tolerated with a walker. Physical therapy was begun immediately to regain motion and strengthen the limb.
    • Due to the patient’s history of breast cancer, she was considered at high risk for thromboembolic complications. She began injections with low molecular weight heparin 1 day after surgery and continued thromboprophylaxis for 4 weeks.

    Patient Progress

    Initial 6-week postoperative visit after left patellofemoral arthroplasty

    • Minimal pain, no crepitus with left knee motion; patella tracking well
    • Range of motion 0-130° (preoperative motion 5-120°)
    • Incision well healed
    • Minimal residual swelling present
    • Continuing to make gains in physical therapy
    • Radiographic imaging of the left knee: well-fixed, well-positioned patellofemoral arthroplasty (Figure 2)

    Figure 2. Postoperative X-rays following left patellofemoral arthroplasty.

    Three months after the left patellofemoral arthroplasty, the patient underwent a successful right patellofemoral arthroplasty, with similar protocols.

    6-week postoperative visit after right patellofemoral arthroplasty

    • Mild discomfort in the right knee
    • Range of motion 0-135° (preoperative motion 0-120°)
    • Incision well healed
    • Moderate effusion, aspirated under sterile conditions for 30 mL of serosanguinous fluid
    • Continuing to make gains in physical therapy
    • Radiographic imaging of the right knee: well-fixed, well positioned patellofemoral arthroplasty (Figure 3)

    3-month postoperative visit after right patellofemoral arthroplasty

    • Mild effusion
    • Patella tracks well
    • Good quadriceps strength
    • Increased activity

    Figure 3. Postoperative X-rays following right patellofemoral arthroplasty.

    Author Information

    Julie Shaner, MD, is an orthopaedic surgery resident at Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, Pennsylvania. Jess H. Lonner, MD, is a board-certified orthopaedic surgeon from The Rothman Institute, Philadelphia, Pennsylvania. He specializes in the treatment of arthritis of the knee.

    Adult Reconstruction Section Editor, Rothman Institute Grand Rounds

    Antonia F. Chen, MD, MBA


    1. Shaner J, Lonner JH. A resurgence for patellofemoral arthroplasty. ICJR.net. Published February 13, 2015; accessed February 26, 2015.