Chronic post-surgical pain can be a considerable issue for patients undergoing primary total knee arthroplasty. According to the literature, persistent knee pain is experienced by up to 44% of patients. Most studies on total knee arthroplasty (TKA) outcomes have mainly investigated the biomechanics or function of the operated knee, but chronic pain has never been a primary issue. In recent years several possible predictors of chronic postsurgical pain have been investigated and eventually identified. A younger age, female gender, psychological distress, preoperative pain duration and intensity were all reported to influence chronic postoperative pain rates after total knee arthroplasty. Recently, it has also been hypothesized that preoperative signs of centrally driven hyperalgesia and distorted pain modulation may predict persistent knee pain in some patients. Despite the considerable number of patients suffering from chronic postsurgical pain after TKA, available data is scarce, and well controlled prospective studies are lacking. Predictors of chronic postsurgical pain after total knee arthroplasty have yet to be identified. Thus, this article is aimed at reviewing current knowledge on persistent pain after knee arthroplasty.

Background. Despite good results of total knee arthroplasty (TKA) as a treatment of idiopathic osteoarthritis (OA) of the knee, significant number of patients (16-33%) complain of persistent pain of unknown origin. This phenomenon is the major cause of patient’s dissatisfaction. It has been theorized that certain preoperative factors may increase the risk of persistent pain; hence, their identification should enable proper preoperative education and development of realistic expectations regarding results of TKA. This study is aimed at identifying the preoperative chronic pain predictors in patients undergoing TKA. Methods. In this prospective cohort study, patients scheduled for TKA were examined one day prior to surgery. Demographics, comorbidities, pressure pain thresholds, pain intensity and duration, radiographic OA grade, and range of motion were recorded. Questionnaires such as Beck Depression Inventory (BDI) and Knee Injury and Osteoarthritis Outcome Score (KOOS) were collected. Study cohort was evaluated approximately 6 months following surgery. Patients were assigned to group A if they had no pain and to group B if they complained of any pain. Collected data was analyzed by biostatistician. Results. 64 patients were included in final analysis, 49 (76,6%) females and 15 (23,4%) males. Mean age was 67,6 yrs (48-84, ±7,42). Group A consisted of 21 patients (33%) while group B consisted of 43 patients (67%). There were no statistically significant differences regarding preoperative factors except for duration of preoperative pain, which was shorter in group A (36 (12-180) vs. 72 (24-180), p = 0,011 ). Every 12 months of preoperative pain were found to increase risk of persistent pain by 1,27 ( p = 0,009 ). Conclusions. Preoperative duration of pain is a risk factor for chronic pain following TKA. Therefore, patients should be operated on as soon as indications arise. Should the surgical treatment of knee arthritis be postponed, intensive and individualized pain management is highly recommended.

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Purpose Despite good results of total knee arthroplasty (TKA) number of patients (16–33%) complain of persistent pain. It has been theorized that certain preoperative factors may increase risk of persistent pain, hence their identification should improve preoperative education regarding results of TKA. Methods Patients scheduled for TKA were examined one day prior to surgery. Demographics, comorbidities, pressure pain thresholds, pain intensity and duration, radiographic OA grade and range of motion were recorded. Beck Depression Inventory (BDI) and Knee injury and Osteoarthritis Outcome Score (KOOS) were collected. Study cohort was evaluated 6 months following surgery. Patients were assigned to group A if they had no pain and to group B if they complained of any pain. Results 64 patients were included in final analysis. There were no statistically significant differences regarding preoperative factors except for duration of preoperative pain, which was shorter in group A [36 (12–180) vs 72 (24–180), p = 0,011294]. Every 12 months of preoperative pain were found to increase risk of persistent pain by 1,27 (p = 0,008779). Conclusions Preoperative duration of pain is a risk factor for chronic pain following TKA. Should the surgical treatment of knee arthritis be postponed, intensive and individualized pain management is highly recommended.

Routine resection of the infrapatellar fat pad (IFP) during total knee arthroplasty (TKA) is controversial, as it may result in shortening of the patellar tendon (PT) and anterior knee pain. This prospective study examined whether IFP excision during TKA affects joint function, anterior knee pain, PT dimensions and sonographic structure. A total of 65 consecutive patients undergoing TKA for osteoarthritis were randomized into two groups: IFP was resected in one and retained in the other. Patients were examined preoperatively, at 6 weeks and 6 months postoperatively: pain (Numerical Rating Scale—NRS), range of motion (ROM) and knee function (Knee Injury and Osteoarthritis Outcome Score—KOOS score) were evaluated; sonographic examination determined the length, structure and vascularity of the PTs. In both groups there were postoperative improvements in NRS and KOOS scores, although IFP resection did not influence clinical outcomes or sonographic parameters. At 6 weeks and 6 months postoperatively for both groups there were no differences between NRS scores (Mann–Whitney test, p = 0.511 and p = 0.579), ROM scores (Mann–Whitney test, p = 0.331, p = 0.180) or all KOOS subscores. IFP excision had no effect on sonographic parameters. This study suggests that IFP resection during TKA does not influence postoperative functional outcomes, pain scores, patellar tendon length and thickness, or sonographic structure.