Evolution and characteristics of nocturnal knee pain after knee arthroplasty

Nocturnal knee pain and sleep disorders are two common but poorly studied issues contributing to dissatisfaction following knee arthroplasty. This study aims to evaluate the prevalence and associated factors of nocturnal pain and sleep disturbance in a population undergoing knee arthroplasty.

We included in this prospective observational study 111 patients undergoing knee athroplasty (79 TKA and 32 UKA). Sleep quality, nocturnal knee pain (preoperatively, at day 3, at 3 and 6 weeks, at 3 months and one year after surgery), pain during mobilization and neuropathic pain were evaluated by scores. Painkillers and sleeping pills intake were recorded. Potentially predictive factors for postoperative nocturnal pain evolution were studied.

Poor sleeping quality rate was 54% for the pre-operative patients and was still 53% at one year after surgery. The prevalence of nocturnal knee pain was 38,74% before surgery and 2,9% at one year after arthroplasty. This study has been performed at the University Hospital Saint Luc Brussels. Evolution and Characteristics of nocturnal knee pain after knee arthroplasty. Nocturnal pain after knee surgery was significantly associated with higher pain scores at rest during activity and at night. Nocturnal pain was significantly associated with a higher PSQI and DN4 scores and a higher consumption of painkillers or sleeping pills at W6. The multiple variable regression showed a statistically significant correlation between preoperative and postoperative nocturnal pain at D3 and W3. Compared to TKA, UKA patients reported significantly less nocturnal pain at W3 and W6.

Bad sleeping quality is present in 54% of knee arthroplasty patients before and after surgery. Nocturnal pain is present in 39% of knee arthroplasty patients before surgery and this drops to 3% after one year. Nocturnal pain is associated with higher pain intensity, neuropathic symptoms, increased medication consumption and poor sleeping quality. Night pain disappeared faster after UKA than TKA, with a tipping point around 6 weeks postoperatively.