Although total knee arthroplasty is a successful and cost-effective procedure, patient dissatisfaction remains as high as 50%. Postoperative residual knee pain after total knee arthroplasty, with or without crepitation, is a major factor that contributes to patient dissatisfaction. The most common location for residual pain after total knee arthroplasty is anteriorly. Because residual pain has been associated with an un-resurfaced patella, this review includes only registry data and total knee arthroplasty with patella replacement. Some suggest that the pathogenesis of residual knee pain may be related to mechanical stimuli that activate free nerve endings around the patellofemoral joint. Various etiologies have been implicated in residual pain, including (1) low-grade infection, (2) midflexion instability, and (3) component malalignment with patellar maltracking. Less common causes include (4) crepitation and patellar clunk syndrome; (5) patellofemoral symptoms, including overstuffing and avascular necrosis of the patella; (6) early aseptic loosening; (7) hypersensitivity to metal or cement; (8) complex regional pain syndrome; and (9) pseudoaneurysm. Because all of these conditions can lead to residual pain, identifying the etiology can be a difficult diagnostic challenge. Often, patients with persistent pain and normal findings on radiographs and laboratory workup may benefit from a diagnostic injection or further imaging. However, up to 10% to 15% of patients with residual pain may have unexplained pain. This literature review summarizes the findings on the causes of residual pain and presents a diagnostic algorithm to facilitate an accurate diagnosis for residual pain after total knee arthroplasty.

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Background:Body checking is a common cause of youth ice hockey injuries. Consequently, USA Hockey raised the minimum age at which body checking is permitted from the Pee Wee level (11-12 years old) to the Bantam level (13-14 years old) in 2011.Purpose/Hypothesis:The purpose of this investigation was to determine the impact of body checking on the distribution of injuries reported in youth ice hockey players. We hypothesized that the elimination of body checking at the Pee Wee level would lower the frequency of serious injuries, particularly concussions.Study Design:Descriptive epidemiology study.Methods:Injury data from the National Electronic Injury Surveillance System (NEISS), a United States Consumer Product Safety Commission database, were analyzed for Pee Wee and Bantam players between January 1, 2008 and December 31, 2010 and again between January 1, 2013 and December 31, 2015. Data on the location of injury, diagnosis, and mechanism of injury were collected. The location of injury was categorized into 4 groups: head and neck, upper extremity, lower extremity, and core. Diagnoses investigated included concussions, fractures, lacerations, strains or sprains, internal organ injuries, and other. The mechanism of injury was broken down into 2 categories: checking and other.Results:Between the 2008-2010 and 2013-2015 seasons, overall injuries decreased by 16.6% among Pee Wee players, with injuries caused by body checking decreasing by 38.2% (P = .012). There was a significant change in the distribution of diagnoses in the Pee Wee age group during this time frame (P = .007): strains or sprains, internal organ injuries, and fractures decreased in frequency, while the number of concussions increased by 50.0%. In the Bantam age group, recorded injuries decreased by 6.8%, and there was no change in the distribution of the location of injury, diagnosis, or mechanism of injury (P > .05).Conclusion:There was an observed reduction in the total number, mechanism, and type of injuries when body checking was eliminated from the Pee Wee level. There was, however, an unexpected increase in the number of concussions.