The 6-year trajectory of non-traumatic knee symptoms (including patellofemoral pain) in adolescents and young adults in general practice: a study of clinical predictors M Kastelein, 1 P A J Luijsterburg, 1 E M Heintjes, 1 M van Middelkoop, 1 J A N Verhaar, 2 B W Koes, 1 S M A Bierma-Zeinstra 1,2 1 Department of General Practice, Erasmus MC University Medical Center, Rotterdam, The Netherlands 2 Department of Orthopaedics, Erasmus MC University Medical Center, Rotterdam, The Netherlands Correspondence to Dr P A J Luijsterburg, Department of General Practice, Erasmus MC University Medical Center Rotterdam, PO Box 2040, Rotterdam 3000 CA, The Netherlands; p.luijsterburg@erasmusmc.nl Accepted 11 November 2014 Published Online First 27 November 2014 To cite: Kastelein M, Luijsterburg PAJ, Heintjes EM, et al. Br J Sports Med 2015;49: 400–405. ABSTRACT Aims (1) To assess the 1-year and 6-year courses of non- traumatic knee symptoms in adolescents and young adults presenting in general practice. (2) To identify prognostic factors for persistent knee symptoms at 1-year follow-up. Methods Adolescents and young adults (12–35 years; n=172) with non-traumatic knee symptoms were included in the cohort study by their general practitioner (GP) and followed for 6 years. Multivariable logistic regression analysis was used to identify prognostic factors for persistent knee symptoms at 1-year follow-up and the area under the receiver operating curve (AUC) was calculated. Results Persistent knee symptoms in patients receiving a GP diagnosis of unspecified knee symptoms were reported by 41% of the patients at 1-year follow-up and by 19% of the available patients at 6-year follow-up. Patients receiving a GP diagnosis of patellofemoral pain syndrome had the worse prognosis, with 40% reporting persistent knee symptoms at 6-year follow-up. Prognostic factors associated with persistent knee symptoms at 1-year follow-up were BMI >25, low/middle education level, bilateral symptoms and self-reported absence of crepitus of the knee (AUC 0.80) for patients receiving a GP diagnosis of unspecified knee symptoms. For patients receiving a GP diagnosis of patellofemoral pain syndrome, prognostic factors were low/middle education level, poor health, having bilateral symptoms and self- report of a swollen knee (AUC 0.76). Conclusions The prognosis of non-traumatic knee symptoms in adolescents and young adults in general practice is not as good as was previously assumed. Several prognostic factors collected at baseline were associated with persistent knee symptoms at follow-up. However, the results should be replicated in another larger study. INTRODUCTION General practitioners (GPs) are frequently con- sulted by patients with non-traumatic knee symp- toms. Non-traumatic knee symptoms in adolescents and young adults account for 20% of all non- traumatic knee symptoms in general practice and include patellofemoral pain syndrome, 1 jumper’s knee (knee extensor tendinopathy), Osgood- Schlatter disease, bursitis, iliotibial tract friction syndrome and popliteal cysts. 2 The incidence of these types of symptoms in adolescents and young adults reported in general practice is about 19/ 1000 patients per year. 2 In comparison with sports medicine, the patello- femoral pain syndrome accounts for up to 25% of all presented knee symptoms. 34 To the best of our knowledge, no studies have examined the short- term and long-term follow-up and prognosis of these symptoms in adolescents and young adults in general practice. 5 Therefore, this prospective cohort study was per- formed in general practice to assess the 1-year and 6-year courses of non-traumatic knee symptoms in adolescents and young adults, and to identify prog- nostic factors for persistent knee symptoms at 1-year follow-up. METHODS Design The present study took place within the research network HONEUR (40 GPs) established by the department of General Practice of Erasmus MC University Medical Centre. It is part of a prospective, observational cohort study (n=1068) in which con- secutive patients visiting their GP with a new episode of knee symptoms were enrolled and initially fol- lowed for 1 year. 6 Owing to the high percentage of persistent knee symptoms at 1-year follow-up, the follow-up period was extended to 6 years. At baseline, new knee symptoms were defined as episodes of knee pain presented to the GP for the first time. Recurrent symptoms for which the GP was not consulted within the past 3 months were also considered to be new symptoms. Traumatic knee symptoms were defined as knee symptoms caused by a sudden impact or unexpected move- ment within 1year before consulting the GP. All other knee symptoms were considered to be non- traumatic knee symptoms. Patients were eligible for this study if they were aged 12–35 years and had consulted their GP for non-traumatic knee symptoms (unspecified knee symptoms (ICPC L15) and patellofemoral pain syn- drome (ICPC L99.07). Exclusion criteria were knee symptoms that required urgent medical attention (eg, fractures, infection), patients with malignan- cies, neurological disorders or musculoskeletal dis- eases (eg, Parkinson’s disease, rheumatoid arthritis, amyotrophic lateral sclerosis), as well as patients incapable of understanding the ramifications of study participation. The study protocol was approved by the Medical Ethics committee of the Erasmus MC University Medical Centre. Kastelein M, et al. Br J Sports Med 2015;49:400–405. doi:10.1136/bjsports-2014-093557 1 of 7 Original article on April 25, 2020 by guest. Protected by copyright. http://bjsm.bmj.com/ Br J Sports Med: first published as 10.1136/bjsports-2014-093557 on 27 November 2014. Downloaded from