Background: Anterior knee pain, which has a prevalence of 4% to 49% after TKA, may be a cause of patient dissatisfaction after TKA. To limit the occurrence of anterior knee pain, patellar denervation with electrocautery has been proposed. However, studies have disagreed as to the efficacy of this procedure.Questions/purposes We evaluated patients undergoing bilateral, simultaneous TKA procedures without patellar resurfacing to ask: (1) Does circumferential patellar cauterization decrease anterior knee pain (Kujala score) postoperatively compared with non-cauterization of the patella? (2) Does circumferential patellar cauterization result in better functional outcomes based on patient report (VAS score, Oxford knee score, and Knee Injury and Osteoarthritis Outcome Score) than non-cauterization of the patella? (3) Is there any difference in the complication rate (infection, patellar maltracking, fracture, venous thromboembolism, or reoperation rate) between cauterized patellae and non-cauterized patellae?
Methods: Seventy-eight patients (156 knees) were included in this prospective, quasi-randomized study, with each patient serving as his or her own control. Patellar cauterization was always performed on the right knee during simultaneous, bilateral TKA. Five patients (6%) were lost to follow-up before the 2-year minimum follow-up interval. A single surgeon performed all TKAs using the same type of implant, and osteophyte excision was performed in all patellae, which were left unresurfaced. Patellar cauterization was performed at 2 mm to 3 mm deep and approximately 5 mm circumferentially away from the patellar rim. The preoperative femorotibial angle and degree of osteoarthritis (according to the Kellgren-Lawrence grading system) were measured. Restoration of the patellofemoral joint was assessed using the anterior condylar ratio. Clinical outcomes, consisting of clinician-reported outcomes (ROM and Kujala score) and patient-reported outcomes (VAS pain score, Oxford knee score, and Knee Injury and Osteoarthritis Outcome Score), were evaluated preoperatively and at 1 month and 2 years postoperatively. Preoperatively, the radiologic severity of osteoarthritis, based on the Kellgren-Lawrence classification, was not different between the two groups, nor were the baseline pain and knee scores. The mean femorotibial angle of the two groups was also comparable: 189° ± 4.9° and 191° ± 6.3° preoperatively (p = 0.051) and 177° ± 2.9° and 178° ± 2.1° postoperatively (p = 0.751) for cauterized and non-cauterized knees, respectively. The preoperative (0.3 ± 0.06 versus 0.3 ± 0.07; p = 0.744) and postoperative (0.3 ± 0.06 versus 0.2 ± 0.07; p = 0.192) anterior condylar ratios were also not different between the cauterized and non-cauterized groups.
Results: At the 2-year follow-up interval, no difference was observed in the mean Kujala score (82 ± 2.9 and 83 ± 2.6 for cauterized and non-cauterized knees, respectively; mean difference 0.3; 95% confidence interval, -0.599 to 1.202; p = 0.509). The mean VAS pain score was 3 ± 0.9 in the cauterized knee and 3 ± 0.7 in the non-cauterized knee (p = 0.920). The mean ROM was 123° ± 10.8° in the cauterized knee and 123° ± 10.2° in the non-cauterized knee (p = 0.783). There was no difference between cauterized and non-cauterized patellae in the mean Knee Injury and Osteoarthritis Outcome Score for symptoms (86 ± 4.5 versus 86 ± 3.9; p = 0.884), pain (86 ± 3.8 versus 86 ± 3.6; p = 0.905), activities (83 ± 3.2 versus 83 ± 2.8; p = 0.967), sports (42 ± 11.3 versus 43 ± 11.4; p = 0.942), and quality of life (83 ± 4.9 versus 83 ± 4.7; p = 0.916), as well as in the Oxford knee score (40 ± 2.1 versus 41 ± 1.9; p = 0.771). Complications were uncommon and there were no differences between the groups (one deep venous thromboembolism in the cauterized group and two in the control group; odds ratio 0.49, 95% CI, 0.04-5.56; p = 0.57).
Conclusions: Patellar cauterization results in no difference in anterior knee pain, functional outcomes, and complication rates compared with non-cauterization of the patella in patients who undergo non-resurfaced, simultaneous, bilateral, primary TKA with a minimum of 2 years of follow-up. We do not recommend circumferential patellar cauterization in non-resurfaced patellae in patients who undergo TKA.
Level of evidence: Level II, therapeutic study.