Purpose

The purpose of the present systematic review was to investigate the progression of patellofemoral (PF) osteoarthritis (OA) after medial open wedge high tibial osteotomy (OWHTO), and whether PF OA progression has an influence on clinical outcomes.

Methods

According to Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA), Three databases (EMBASE, PubMed and Cochrane Library) were searched independently in June 2020 for English-language studies that presented data on PF OA or cartilage degeneration before and after OWHTO. The inclusion criteria were as follows: 1) medial OWHTO, 2) evaluating PF OA or cartilage degeneration before and after surgery, 3) reporting clinical outcomes after the surgery. Quality assessment of non-randomized cohort studies and case series was performed using the Methodological Index for Non-Randomized Studies (MINORS) quality assessment tool. Descriptive statistics are presented.

Results

A total of 20 studies including 1,173 patients were included. Of those, ten studies were level III, and the other ten studies were level IV. The mean age at the surgery was 57.1 years (range, 18 to 84) with 826 (70.4%) female. The mean follow-up period was 27.1 months (range, 7 to 144). Ten studies reported the trochlear International Cartilage Research Society (ICRS) scores pre- and post-operatively, with each of these studies reporting a higher proportion of patients with grades 2-4 OA post-operatively compared to pre-operatively (relative risks = 1.19 to 2.76). Similarly, seven studies reported patellar ICRS scores and found a higher proportion with grades 2-4 OA post-operatively (relative risks = 1.08 to 2.44). Four studies assessed PF Kellgren-Lawrence grade each of which reported a higher proportion of patients with grades 2-4 OA post-operatively (relative risks = 1.25 to 21.0). Only three studies reported clinical outcomes for patients with and without progression of PF OA using Knee Injury and Osteoarthritis Outcome Score (KOOS), Kujala score, or Knee Society Score (KSS). One study (94 knees) assessed KOOS and Kujala score, and reported that there was clinically and statistically significant worsening in postoperative Kujala score (p = 0.005), KOOS-pain (p = 0.005), KOOS-activities in daily living (p = 0.017), KOOS-sports and recreational function (p = 0.023), and KOOS-knee-related quality of life (p = 0.012) in the progression group compared with non-progression group. The remaining two studies (109 knees) reported that there was no statistically significant difference in postoperative KSS between with and without progression of PF OA. Outcome reporting was variable across these studies, and effect of progression of PF OA on clinical outcome could not be definitively determined.

Conclusion

Medial OWHTO patients appear to have progression of trochlea and patella OA post-operatively. There is currently a lack of studies to make meaningful conclusions for the effect that PF OA can have on clinical and functional outcomes; thus, the clinical effect of PF OA progression after medial OWHTO remains uncertain, and further comparative studies are needed.