Early Detection May Mitigate Persistence of Pain After Total Knee Replacement

Long-term, chronic pain after total knee replacement may be common and appears to be established at 6 months, according to results of a study published in Orthopaedics & Traumatology: Surgery & Research.

Patients (N=65) who underwent total knee replacement for primary knee osteoarthritis between 2011 and 2012 at Lille University Hospital in France were prospectively enrolled in this study. The study participants completed questionnaires about pain and other outcomes the night before surgery, at 6 months after surgery, and 7.5 years after surgery. The rate and predictors of chronic pain were evaluated.

The mean age of study participants was 73.6 (standard deviation [SD], 10.2) years, 72.3% were women, mean body mass index (BMI) was 31.8 (SD, 6.4) kg/m², 20% had undergone total knee replacement of the contralateral knee, 84.6% had undergone prior knee arthroscopy, and 70.1% underwent surgery for prior knee trauma. Most patients (89.2%) underwent posterior-stabilized total knee replacement, and the average duration of postoperative rehabilitation was 4 (SD, 2.9) weeks.

At 6 months, improvement from baseline was noted for the following: pain scores using the numerical pain rating scale (mean, 2.3 vs 6.5 points; P <.001), function scores using the Oxford Knee Scale (mean, 33.5 vs 19.5 points; P <.001), anxiety scores using the Hospital and Anxiety Depression Scale (mean, 4.9 vs 8.3 points; P <.001), and Pain Catastrophizing Scale scores (mean, 6.5 vs 18 points; P <.001).

At long-term follow-up at 7.5 years, no significant changes for any outcomes were observed compared with 6 months, indicating that pain scores and functional outcomes stabilized within 6 months of surgery.

At the final follow-up visit, numerical pain rating scale and pain catastrophizing scores were correlated (S, 0.312; P =.011).

Among the subset of patients (26.5%) who reported chronic pain at the final follow-up visit, half reported experiencing neuropathic pain. Despite this high proportion, the overall proportion of patients reporting neuropathic pain decreased at 7.5 years (18.5%) from the preoperative assessment (40%; P =.007). Only one-third of patients with neuropathic pain at the final follow-up visit were receiving treatment for their symptoms.

Major limitations of this study include its single-center design, self-reporting using questionnaires, and exclusion of a large number of patients who were lost to follow-up.

These data indicate that although many patients who undergo total knee replacement report chronic pain, the knee pain can be considered to be stable by 6 months after surgery. The study authors commented, “Early detection is vital to prevent the pain from becoming chronic, which makes it more difficult to treat.” Pain management referral and evaluation of anxiety and depression symptoms and pain catastrophizing prior to surgery are also recommended.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.