Patellofemoral pain syndrome (PFPS), aka 'runners knee' is one of the most common forms of knee pain in adults under the age of 40.1
PFPS is characterised by diffuse and often vague pain about the front and underside of the knee-cap and is aggravated with squatting, prolonged sitting, stair climbing as well as running.2
I have treated several clients over the past few months who, due to COVID-19 restrictions, took up outdoor running. Continuing to exercise, especially outdoors, has immense benefits; however, if the body is not prepared for running, problems can occur.
One reason for developing PFPS may be due to an 'imbalance' between the inner (vastus medialis) and outer (vastus lateralis) thigh muscles.3 Effectively if both muscles don't engage at or almost at the same time, an uneven tension may be applied to the knee cap to which these muscles attach. The result is the knee-cap not moving correctly on the front of the knee which may result in an irritation of the underside of the knee-cap as well as the surrounding structures, leading to pain and sensitivity. Such an imbalance of the thigh (quadriceps) muscles may occur due to prolonged sitting, periods of inactivity or due to other exercises which do not emphasise a balanced activation of the thigh muscles.
PFPS can be very limiting, often reducing the ability to exercise and perform other physical and work-related activities.2 PFPS is a refractory condition that, if not correctly treated, may persist for many years and is a likely contributor to long-term osteoarthritis affecting the underside of the knee-cap (the patellofemoral joint).4
A recent study investigated the effects of trigger point dry needling (TrP-DN) of the thigh muscles on exercise-induced PFPS.5 Dry needling is a medical acupuncture technique, used to 'deactivate' sensitive muscle knots known medically as myofascial trigger points. The presence of trigger points in the thigh muscles may contribute to the muscle imbalance scenario described above.
The study involved two groups; however, I will focus on the group who received proper TrP-DN for the sake of interest and clinical relevance.
The proper TrP-DN group of patients received a single session of TrP-DN to trigger points in the inner, outer and middle thigh muscles once a week for six weeks. After each session, a stretching exercise was done. The researchers also carried out a myoelectric analysis which allowed them to work out the ratio of activation of the inner to outer thigh muscles; a 1:1 ratio would suggest a balanced muscle activation, less than 1:1 would indicate an imbalance, usually due to a delay in the inner thigh muscle.
After treatment, the group reported significantly less pain and improved function (according to VAS and Kujala scores) at the 3-week treatment visit, 6-week treatment visit, and 3-month follow-up compared to their scores before treatment. Furthermore, myoelectric ratio testing of the inner and outer thigh muscles showed improvements compared to tests performed before treatment.
In summary, according to this study, TrP-DN of the thigh muscles combined with stretches can reduce pain, improve function and improve muscle activation imbalances leading to improved coordination of the thigh muscles in patients with PFPS.5
The treatment approach used is very similar to that which I use in the clinic when treating clients with PFPS. I have found it clinically beneficial also to include needling myofascial trigger points (if present) within the musculature of the hip and pelvic girdle. Further specific strengthening exercises and manual therapy techniques are also effective depending on assessment findings.
As with most conditions, success is determined by having a wide range of techniques to choose from, then knowing which techniques to use and when to get the best results.
1. Dey P, Callaghan M, Cook N, Sephton R, Sutton C, Hough E, James J, Saqib R, Selfe J. A questionnaire to identify patellofemoral pain in the community: an exploration of measurement properties. BMC musculoskeletal disorders. 2016 Dec 1;17(1):237.
2. Crossley KM, Stefanik JJ, Selfe J, et al. Patellofemoral pain consensus statement from the 4th international patellofemoral pain research retreat, manchester. Part 1: terminology, definitions, clinical examination, natural history, patellofemoral osteoarthritis and patient-reported outcome measures. Br J Sports Med. 2016;50:839–843. doi:10.1136/bjsports-2016-096384
3.Lorenz A, Müller O, Kohler P, Wünschel M, Wülker N, Leichtle UG. The influence of asymmetric quadriceps loading on patellar tracking—an in vitro study. The Knee. 2012 Dec 1;19(6):818-22.
4. Thomas MJ, Wood L, Selfe J, Peat G. Anterior knee pain in younger adults as a precursor to subsequent patellofemoral osteoarthritis: a systematic review. BMC musculoskeletal disorders. 2010 Dec 1;11(1):201.
5. Ma YT, Li LH, Han Q, Wang XL, Jia PY, Huang QM, Zheng YJ. Effects of trigger point dry needling on neuromuscular performance and pain of individuals affected by patellofemoral pain: a randomized controlled trial. Journal of Pain Research. 2020;13:1677.