Activity Modification and Load Management of Adolescents with Patellofemoral Pain: A Prospective Intervention Study Including 151 Adolescents

Key Points

1. Patellofemoral pain (PFP) is a common complaint among active adolescents.
2. Exercise therapy is an effective treatment for PFP in adults, but less so in adolescents, perhaps because it usually fails to include load management and activity modification.
3. In this study, load management and activity modification combined with exercise was effective in treating PFP in adolescents.

BACKGROUND & OBJECTIVE

Patellofemoral pain (PFP) is a common problem for highly active adolescents. Most treatment strategies focus on exercise, and neglect activity modification and load management. The purpose of this study was to investigate the effects of a treatment strategy focused on activity modification and load management.

Patellofemoral pain is a common problem for highly active adolescents.

Clinicians should consider prioritizing load management and activity modification in clients with patellofemoral pain.

METHODS

Researchers recruited 151 adolescents aged 10 to 14 years with PFP. The participants underwent a 12-week intervention including 4 supervised sessions with a physical therapist.

Weeks 1-4 included activity modification according to an “activity ladder” and pain monitoring. Weeks 5-8 focused on home-based exercises. Weeks 9-12 were based on return-to-sport guidance.

The primary outcome was a 7-point global rating of change, ranging from ‘‘much improved’’ to ‘‘much worse.’’ Secondary outcomes included the Knee Injury and Osteoarthritis Outcome Score (KOOS), hip and knee torque, sports participation, satisfaction with treatment, and use of painkillers.

Data was collected at one month, three months, six months, and one year.

RESULTS

On the 7-point global rating of change score, a response of “improved” or “much improved” was considered a “successful outcome”. At 12 weeks, 87% of the participants completed the full questionnaire, and of this group, 86% reported a “successful outcome.” At 6 months, 77% reported a successful outcome, and at 52 weeks the percentage was 81%.

On the KOOS sub-scores, there were large clinically-relevant improvements in pain, sport/recreation, and quality of life (13-24 points). Hip and knee torque increased by 20% to 33%.

68% of participants returned to sport after 3 months, with these percentages increasing to 79% at 6 months and 81% at 12 months. 90% of the participants were satisfied with the treatment.

LIMITATIONS

There was no control group in this study, thus it is unknown whether the intervention would have worked better than an exercise-based intervention or no intervention at all. However, given that knee pain lasts on average 18 months, and that exercise-based interventions usually have only moderate effects, there is reason to believe that the strong effects seen in this study derive from activity management and load modification.

CLINICAL IMPLICATIONS

PFP is characterized by diffuse anterior knee pain, and provoked by activities that load the knee, such as squatting and stair climbing (1). It is the second most common knee complaint among adolescents, affecting 6% of the general population, and 25% of sports participants (2). The primary cause is thought to be repetitive loading of the knee without adequate rest. About 40% of adolescents with PFP will continue to have pain until early adulthood, and this may limit function, sports participation, and quality of life (3).

The most common treatment for PFP is exercise therapy, usually focused on resistance training. This has been shown to be an effective treatment for adults, but less so for adolescents, with only one-third having a positive response (4). This may be due to the fact that adolescents are more active than adults, highly motivated to engage in activities that load the knee and aggravate PFP. Thus, if exercise therapy fails to consider this factor, it is more likely to fail. This study was designed to address this aspect.

One method for load management used in this study was the activity ladder, which distinguished different activities (e.g. easy walking < fast walking < slow running < moderate running and jumping < fast running and jumping) based on their potential to load the knee and aggravate PFP.

Participants were instructed to move to a higher step on the ladder only if pain stayed in the “OK Zone” (defined as pain of less than four on a ten-point scale). Return to sport was progressed by starting with participation in the warm up, and then adding 15 minutes per week of practice, again making sure pain remained in the “OK Zone”.

Based on the positive results in this study, clinicians should consider prioritizing load management and activity modification in clients with PFP, especially those who are highly active.

+STUDY REFERENCE

[Rathleff M, Graven-Nielsen T, Hölmich P, et al (2019) Activity Modification and Load Management of Adolescents With Patellofemoral Pain: A Prospective Intervention Study Including 151 Adolescents. Am J Sports Med, 47(7), 1629-1637.]()

SUPPORTING REFERENCE

1. Crossley KM, Stefanik JJ, Selfe J, et al. 2016 Patellofemoral pain consen- sus statement from the 4th International Patellofemoral Pain Research Retreat, Manchester. Part 1: terminology, definitions, clinical examination, natural history, patellofemoral osteoarthritis and patient-reported out- come measures. Br J Sports Med. 2016;50(14):839-843
2. Smith BE, Selfe J, Thacker D, et al. Incidence and prevalence of patellofemoral pain: a systematic review and meta-analysis. PLoS One. 2018;13(1):e0190892
3. Rathleff MS, Holden S, Straszek CL, Olesen JL, Jensen MB, Roos EM. Five-year prognosis and impact of adolescent knee pain: a prospective population-based cohort study of 504 adolescents in Denmark. BMJ Open. In press. doi:10.1136/bmjopen-2018- 024113
4. Rathleff MS, Vicenzino B, Middelkoop M, et al. Patellofemoral pain in adolescence and adulthood: same same, but different? Sports Med. 2015;45(11):1489-1495.