The impact of patellofemoral joint diseases on functional outcomes and prosthesis survival in patients undergoing unicompartmental knee arthroplasty: a systematic review and meta-analysis

Abstract

Background: Patellofemoral joint (PFJ) diseases are chronic degenerative conditions that contribute to knee joint symptoms. Unicompartmental knee arthroplasty (UKA) is widely regarded as an effective treatment for knee osteoarthritis (KOA); however, its specific indications remain a subject of debate.

Hypothesis: Patients with PFJ disease are expected to experience outcomes post-UKA comparable to those of patients without PFJ disease.

Methods: We conducted this meta-analysis following the guidelines outlined by the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). A comprehensive search of PubMed, Embase, and Web of Science databases was conducted for studies examining the association between PFJ disease and UKA, including publications up to September 2024. Extracted data encompassed author, publication year, country, disease type, prosthesis type, sample size, mean patient age, gender distribution, follow-up duration, PFJ disease prevalence at surgery, diagnostic methods, and whether PFJ disease was considered a contraindication for UKA. To maintain objectivity, only studies in which PFJ diseases were visually identifiable were included in the meta-analysis. Statistical analyses were performed using Stata 15.0 and Review Manager 5.4.1. A random-effects meta-analysis was conducted to evaluate the Oxford Knee Score (OKS), Knee Society Score (KSS), flexion range of motion (ROM), Forgotten Joint Score (FJS), Tegner activity score, and prosthesis survival rate, with outcomes stratified by PFJ disease type (PFJ degeneration or patella cartilage injury). Mean differences, confidence intervals, and P values were calculated for comparisons between the PFJ disease and non-PFJ disease groups. The Methodological Index for Non-Randomized Studies (MINORS) criteria and the Newcastle-Ottawa Scale (NOS) were applied to evaluate the risk of bias. To address heterogeneity, sensitivity analyses were performed, and publication bias was assessed using funnel plots and Egger's test.

Results: A total of 14,866 knees from 48 relevant studies were included in this systematic review. Methodological quality was assessed using the MINORS criteria, with case series scoring 11.0/16 and cohort studies scoring 18.2/24. PFJ degeneration emerged as the most studied condition, followed by patella cartilage injury. Clinical outcomes assessments indicated that medial PFJ degeneration, anterior knee pain, patella cartilage damage, and patella baja did not significantly impact UKA outcomes or prosthesis survival. However, severe lateral PFJ degeneration, lateral patellar subluxation, lateral trochlear osteophytes, and patellar bone marrow edema did influence results. Fifteen high-quality studies were included in the meta-analysis, involving 6080 patients-1338 in the PFJ disease group and 4,742 in the non-PFJ disease group. With an average NOS score of 7.2, the studies were generally of high quality. Meta-analysis results showed no significant differences between groups in final follow-up OKS, FJS, Tegner activity score, or prosthesis survival rate. However, the PFJ disease group had lower KSS and reduced flexion ROM compared to the non-PFJ disease group. Subgroup analysis further revealed that the PFJ degeneration group scored lower than the patella cartilage injury group on OKS, KSS, and flexion ROM following UKA.

Conclusion: In summary, PFJ disease was found to have limited impact on UKA outcomes; however, caution is recommended for cases involving severe lateral PFJ degeneration due to potential restrictions in postoperative knee function, particularly affecting flexion ROM in UKA patients.

Keywords: Bicompartmental knee arthroplasty; Knee osteoarthritis; Patellofemoral joint disease; Total knee arthroplasty; Unicompartmental knee arthroplasty.

Fig. 1

PRISMA flow diagram outlining the study selection process

Fig. 2

PFJ diseases covered in this study. A The type and number of studies that oppose or propose PFJ disease as a contraindication to UKA. Oppose vs Propose in PFJ degeneration (26 studies), PFJ cartilage injury (12 studies), anterior knee pain (4 studies), PFCM (2 studies), patella baja (2 studies), BME in the patella (1 study), and lateral subluxation of the patella (1 study). B Proportion of PFJ disease as a contradiction to UKA. Seven studies (14.6%) proposed that PFJ disease was a contraindication for UKA, in contrast, forty-one studies (85.4%) concluded that PFJ disease was not a contraindication for UKA. C Proportion of studies per diagnostic methods. The most used diagnostic method was radiology (52.1%), followed by radiology and visual (31.3%)

Fig. 3

PFJ diseases effects on UKA. A Proportion of studies per arthroplasty device. The most chosen type of arthroplasty was MB UKA (54.2%), followed by FB UKA (39.6%). B Proportion of studies per arthroplasty type. The most chosen type of arthroplasty was medial UKA (85.4%). C The distributions of clinical and functional scores: No difference in green and Significant difference in red. The most used score was KSS (18 studies), followed by OKS (15 studies)

Fig. 4

Meta-analysis illustrating the impact of different types of PFJ diseases on the OKS (A), KSS (B), and flexion ROM (C)

Fig. 5

Meta-analysis illustrating the impact of different types of PFJ diseases on the FJS (A), Tegner activity score (B), and prosthesis survival rate (C)