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Abstract
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Introduction: 10-20% of patients undergoing Total Hip (THA) and Total Knee arthroplasties (TKA) complain of chronic postoperative pain, which is strongly associated with dissatisfaction. Neuropathic Pain (NP) is defined as pain originating from a lesion or disease within the peripheral or central nervous system. Recent studies reported evidence that up to 25% of patients complain of NP preoperatively and up to 35% postoperatively.
Our objective was to longitudinally assess NP pre- to one year postoperative, and its influence on overall pain and satisfaction.
Methods: Prospective cohort study including all patients undergoing either THA or TKA in our tertiary care institution between January 2014 and July 2015. NP was evaluated pre and 1yr postoperative with use of the DN4 score (= neuropathic pain diagnostic questionnaire). We also evaluated its influence on patient overall pain (VAS), function (WOMAC), and satisfaction.
Results: Of 740 TJAs eligible,535 returned the questionnaire (response rate 72.3%). Their mean age was 69.3 (+/-10.9) years, mean BMI 28.1 (+/-5.2) kg/m², 59.3% were women and 58.3% underwent THA.
Among 473 patients without preoperative NP, 22 (4.7%) reported NP one-year postoperatively. Of 62 patients with preoperative NP, 12 (19.4%) had persistent NP one year after surgery. Consequently, there is a risk ratio of 4.16 (95%CI 2.2-8.0, p<0.001) of having postoperative NP for someone with preoperative NP. Most patients with one-year postoperative NP (22/34 = 64.7%) did not have preoperative NP, and 50 out of 62 (80.6%) patients with preoperative NP do not report postoperative NP. Therefore, preoperative NP does not predict satisfaction one year after surgery; this is verified as 411 (87.5%) patients without preoperative NP are satisfied or very satisfied one year after surgery, as compared to 52 (85.2%) patients with preoperative NP.
When compared to patients without NP, the patients with postoperative NP had a significantly higher mean level of pain on VAS (4.1 95%IC 3.5-4.8 vs. 1.7 95%IC 1.5-1.9, p<0.001), and were less satisfied (63.3% vs 87.8%, p<0.001 satisfied to very satisfied patients).
Conclusions: Postoperative NP is more frequent in patients with preoperative NP. However, a majority of patients with postoperative NP did not have preoperative NP. Hence, preoperative NP is not a good outcome predictor. Finally, postoperative NP is strongly associated with poorer clinical outcome and satisfaction.
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