What is the role of patellar resurfacing in total knee arthroplasty for patellofemoral arthritis?

Updated: Dec 11, 2019
  • Author: Dinesh Patel, MD, FACS; Chief Editor: Thomas M DeBerardino, MD  more...
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Answer

The need to perform a patella resurfacing procedure at the time of TKA is still being debated. Some surgeons advocate resurfacing in all patients, while others restrict resurfacing to patients with known patellofemoral arthritis.

Patellofemoral complications after TKA with patella resurfacing are associated with obesity, metal-backed patellar implants, and noncemented patellar components. [56] These complications can include pain, mechanical fracture, loosening, fracture, and maltracking.

Retaining the native patella, however, can result in persistent symptoms of anterior knee pain that can compromise the functional ability of the patient. Furthermore, patients with known osteoarthritis in the tibiofemoral knee compartment are at increased risk for arthritis of the patellofemoral joint.

Some surgeons have suggested that patella resurfacing does not have to be performed if the patellar articular cartilage is normal and if no malalignment is present. The results of several small retrospective studies support the practice of selective resurfacing. In a retrospective study of 185 patients with TKR, pain, functional outcome scores, range of motion, or complications did not differ between those undergoing resurfacing and those not (n = 140). [57]

In a 10-year retrospective follow-up study in 32 knees with a PCL-retaining Press-Fit condylar TKA and no resurfacing, only 1 patient required later revision for patella resurfacing. [58]

Several investigators have asserted that no difference exists between resurfacing and retaining the patella in terms of stair-climbing ability or functional outcome. [59, 60] Furthermore, if the patella is resurfaced and if a complication requiring revision is present, the patella often cannot be resurfaced again because of bone loss. For this reason, some surgeons do not recommend resurfacing in young patients, even when some patellar chondromalacia is present. If the patella is left unresurfaced, the knee system should have an anatomic rather than dome-shaped trochlear groove in the femoral component.

Other orthopedic surgeons believe that a resurfacing procedure should be performed in all patients at the time of a knee arthroplasty. Biomechanically, most prosthetic knees are designed for use with a resurfaced patella.

A study examining the relationship of the patella to different femoral components revealed that retaining the patella results in changes in contact pressures and in the tracking motion in the patellofemoral joint. [61] With flexion of 60° or more, the contact areas shifted from a transverse band across the patella to isolated areas of high pressure on both the medial and the lateral sides of the patella.

All of the prostheses had a significantly greater percentage of patellar contact area subjected to contact pressures above 5 MPa compared with the normal knee with flexion greater than 60°. The patella tracked 3-5 mm more laterally once a prosthesis was in place. This finding may help to explain why some patients without patellofemoral arthritis who have a retained patella may have more difficulty climbing stairs postoperatively than those who undergo a resurfacing procedure.

In a prospective series of 40 patients, those undergoing patellar resurfacing had clinically improved function at a 2-year follow-up in terms of stair climbing and higher functional k scores than those of patients not receiving this procedure. [62] One group in Japan that routinely performed TKA without resurfacing the patella concluded that patellar resurfacing should not be performed routinely but, rather, should be considered for patients with rheumatoid arthritis, who are vulnerable to postoperative thinning of the patella and peripatellar pain. [63]

Boyd and colleagues [14] examined the results of using an unconstrained, condylar, PCL-preserving prosthesis with and without resurfacing in 891 knees and found that the rate of complications was higher in those without resurfacing than in those with resurfacing (4% vs 12%). Patella resurfacing was performed only for specific conditions: loss of cartilage, surface irregularities, and tracking abnormalities. Of patients without resurfacing, 10% required revision for patella resurfacing because of chronic pain. Those with inflammatory arthritis were significantly more likely to require revision for patellar pain than those with osteoarthritis (13% vs 6%).

To the authors' knowledge, no large prospective studies currently provide clarity in this debate. Patients with rheumatoid arthritis seem to do better with a resurfacing procedure. To decrease the incidence of a subsequent revision surgery, most patients would most likely benefit from patella resurfacing at the time of TKA. Functional outcomes, however, seem to be similar when selective nonresurfacing is performed.


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