Why do patellofemoral arthroplasties fail today? A systematic review.
BACKGROUND
Historically poor results of patellofemoral arthroplasty (PFA) were reported in the setting of isolated patellofemoral osteoarthritis (OA). In order to lower PFA failure rates, it is important to identify failure modes using a standardized method. In this systematic review, PFA failure modes were assessed and compared in early vs. late failures and older vs. recent studies.


METHODS
Databases of PubMed, Embase and Cochrane and annual registries were searched for studies reporting PFA failures. Failure modes in studies with mean follow-up <5years were classified as early failures while >5years were classified late failures. Cohorts started before 2000 were classified as older studies and started after 2000 as recent studies.


RESULTS
Thirty-nine cohort studies (10 level II and 29 level III or IV studies) and three registries were included with overall low quality of studies (GRADE criteria). A total of 938 PFA failures were included and were caused by OA progression (38%), pain (16%), aseptic loosening (14%) and patellar maltracking (10%). Pain was responsible for most early failures (31%), while OA progression was most common in late failures (46%). In older studies, OA progression was more commonly reported as failure mode than in more recent studies (53% vs. 39%, p=0.005).


CONCLUSIONS
This level IV systematic review with low quality of studies identified OA progression and pain as major failure modes. Reviewing these studies, appropriate patient selection could prevent PFA failures in select cases. Future studies assessing the role of PFA in isolated patellofemoral OA are necessary.
Computer Assisted Surgery Center, Department of Orthopaedic Surgery, Hospital for Special Surgery, Weill Medical College of Cornell University, New York, NY, USA. Electronic address: vanderlistj@hss.edu.
J P
JP
van der List
Computer Assisted Surgery Center, Department of Orthopaedic Surgery, Hospital for Special Surgery, Weill Medical College of Cornell University, New York, NY, USA. Electronic address: chawlah@hss.edu.
H
H
Chawla
Computer Assisted Surgery Center, Department of Orthopaedic Surgery, Hospital for Special Surgery, Weill Medical College of Cornell University, New York, NY, USA. Electronic address: villaj@hss.edu.
J C
JC
Villa
Computer Assisted Surgery Center, Department of Orthopaedic Surgery, Hospital for Special Surgery, Weill Medical College of Cornell University, New York, NY, USA. Electronic address: pearlea@hss.edu.
A D
AD
Pearle
D019645:Arthroplasty, Replacement, Knee; D015331:Cohort Studies; D006801:Humans; D020370:Osteoarthritis, Knee / Q000601:surgery*; D057071:Patellofemoral Joint; D012042:Registries; D013997:Time Factors; D017211:Treatment Failure
Early failures; Failure modes; Isolated patellofemoral osteoarthritis; PFA; Patellofemoral arthroplasty