Short-term improvement of patellofemoral pain in medial unicompartmental knee arthroplasty with patellar denervation: a prospective comparative study

Introduction: Medial osteoarthritis (OA) knees with symptomatic patellofemoral (PF) arthritis were not recommended for UKA in the past. However, UKA has shown good clinical results in patients with medial OA knee with symptomatic PF arthritis. On the contrary, this procedure is not recommended for patients with severe PF OA. Patella denervation (PD) by circumferential electrocautery can reduce the severity and incidence of anterior knee pain in TKA. However, to the best of our knowledge, there are no studies reporting anterior knee pain and complications of medial UKA with PD in severe PF OA.

Objective: We have conducted a prospective comparative study to assess the short-term results of anterior knee pain and complications after medial UKA with PD or without PD in medial compartment arthritis and severe PF arthritis patients.

Material and methods: This prospective comparative study was conducted from January 2018-September 2019 at Pranungkaew Hospital, Nonthaburi, Thailand. A total of 66 patients with medial compartment and severe patellofemoral arthritis were allocated to UKA with or without patella denervation. The primary outcomes were Kujala anterior knee pain scale and complications measured at 6 months after the surgery.

Results: Sixty-six patients (37 patients undergoing UKA with PD and 27 patients undergoing UKA without PD) of medial compartment and severe lateral facet patellofemoral arthritis (62 female, 4 male; mean age 60.16 (5.03) years; 17 PF grade III, 49 PF grade IV) were included in this study. The mean preoperative Kujala scores were 54.96 (range 30-80) (SD 2.59) in the no-PD group (group I) and 47.77 (range 27-75) (1.62) in the PD group (group II), respectively (p value = 0.009). All baseline characteristics were also comparable between treatment groups except the preoperative Kujala score. The mean final value of Kujala score was 70.22 (range 50-96) (2.40) in the no-PD group (group I) and 80.10 (range 60-95) (SD 1.50) in the PD group (group II), respectively (p value < 0.001). The mean difference of Kujala score was statistically significantly higher by 9.88 (4.48, 15.28) points in the PD group when compared to the no-PD group. There were no complications in both groups after surgery.

Conclusions: Patellar denervation seems to provide short-term benefits improving the Kujala score in patients with PF OA undergoing UKA.

Level of evidence: III. Trial Registration ClinicalTrials.gov: NCT03676179.