Patellar Resurfacing Versus Patellar Retention in Total Knee Arthroplasty - A Randomized Clinical Trial (PROFIX)

University of Alberta

Status and phase: Completed; Phase 4

Conditions: Total Knee Replacement

Treatments: Device: Patellar Replacement Prosthesis; Device: Profix TKR with Patellar Retention

Study type: Interventional

Funder types: Other; Industry

Identifiers

NCT01500252

Pro00002794

Details and patient eligibility

About

Background:

Despite the excellent results of total knee replacement, also known as total knee arthroplasty (TKA) there is persistent controversy over whether or not to replace the surface of the kneecap. Anterior knee pain, which occurs with variable and unpredictable frequency, continues to be a problem in a subset of TKA patients. Some clinicians replace the surface of all kneecaps during TKA to avoid repeat surgery, which occurs in approximately 10% of cases. However, others cite the complications attributed to replacing the surface of kneecap as reasons to avoid this procedure.

This study prospectively randomized patients receiving TKA into two groups, those receiving replacement of the kneecap surface and those left without replacement of the kneecap surface to determine clinical outcomes and revisions over the first 5-10 postoperative years.

Objectives:

The primary objective of this work was to compare pain, stiffness and function between groups at five years postoperatively. Secondarily, we compared pain, stiffness and function at one and 10 years postoperatively. Finally, we examined the number of reoperations following TKR over 10 years in the 2 groups of subjects. The investigators hypothesized that there would be no difference between the two groups of subjects in the measured outcomes.

Methods:

Patients receiving TKA were prospectively enrolled before surgery and randomized intraoperatively to either receive a replacement of the kneecap surface or have no kneecap intervention. The Smith and Nephew Profix TKA system was implanted in all cases; the post-operative regimen was standardized. Subjects were assessed pre-operatively and at 1 and 5 years postoperatively for pain, function, and stiffness using a disease-specific (Western Ontario and MacMaster Osteoarthritis Index [WOMAC]) and generic health status (Short Form 36 [SF-36]) questionnaire. At the end of the five year follow-up, the study was extended to a 10-year followup and the same outcomes were assessed. The revision rate was also compared between the two groups at the end of the 10-year follow-up.

Enrollment: 38 patients

Sex: All

Ages: 40 to 75 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• scheduled for primary TKA to treat non-inflammatory arthritis
• age 40- 75 years of age

Exclusion criteria

• history of knee sepsis
• previous patellectomy
• previous high tibial osteotomy
• knee flexion contracture of >20 degrees
• varus or valgus deformity of > 20 degrees
• < 90 degrees of knee flexion
• tibial or femoral bone deficiency requiring augmentation

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

---

38 participants in 2 patient groups

Patellar Resurfacing

Experimental group

Description:

These subjects received a Profix TKR including an all polyethylene patellar implant.

Treatment:

Device: Patellar Replacement Prosthesis

Patellar Retention

Active Comparator group

Description:

This group received a Profix TKR, but retained their native patella

Treatment:

Device: Profix TKR with Patellar Retention