Comparing the effects of open and closed kinetic chain exercises on pain and functionality in patellofemoral pain syndrome A Pilot Randomized Clinical Trials.

Patellofemoral pain syndrome (PFPS) is the most common cause of anterior knee pain in adolescents and young adults. Gaitonde DY et al., 2019 defined it as pain around or behind the patella that is aggravated by activities that load the patella during weight bearing on the flexed knee. There are many aetiological factors contributing to PFPS. Juhn MS et al., 1999 stated that causes could be overloading due to overuse or overweight, type of foot, muscular causes such as weakness of quadriceps, vastus medialis, hip musculature, or inflexibility like the tightness of the iliotibial band, hamstrings, and calf muscles.

PFPS is also referred to as runner’s knee or anterior knee pain. Annual prevalence in the general population was reported as 22.7%, with the annual prevalence in females 29.2% and males 15.5% and an incidence rate of 1.9% (Bump JM et al., 2023).  Patellofemoral pain is often misdiagnosed as patellofemoral OA, Osgood Schlatter’s disease, plica, bursitis (prepatellar or Hoffa’s), Saphenous neuritis, quadriceps tendinopathy, patellar tendinopathy, or referred pain from hip or back, chondromalacia patella (Smith BE et al., 2018).

Conventional treatment for PFPS primarily focuses on knee strengthening. A study conducted by Avraham F et al., 2007 aiming to find effective physiotherapy treatment for PFPS included 30 participants, divided into group I (received knee rehabilitation and transcutaneous electrical nerve stimulation), group 2 (received hip rehabilitation with stretching) and group 3 (received both the interventions). Results showed significant improvement in terms of pain after 3 weeks but group 2 and group 3 showed significant increase in muscle power when compared to group 1. With the advances in research, now along with knee strengthening, the equal emphasis is being placed on hip strengthening as well. A systematic review conducted by Nascimento LR et al., 2018 on the effectiveness of hip and knee strengthening showed better improvement in pain and activity levels when compared to knee strengthening alone.

Ferber R et al.,  2015 conducted a study on hip and core strengthening versus knee alone in PFPS. Both groups showed similar improvement in pain. The group that received the hip and core strengthening protocol showed earlier resolution of pain i.e. by the third week and increased level of endurance when compared to the knee strengthening protocol.

During recent decades the effects of kinetic chain exercises on patellofemoral pain have been a point of interest to researchers. Kinetic chain exercises are divided into open kinetic chain exercises (OKC) and closed kinetic chain exercises (CKC). In OKC, the proximal segment is fixed and the distal is moving. OKC mainly focuses on isolating a muscle or muscle group. While CKC involves stabilizing the distal segment and moving the proximal segment. CKC primarily focuses on eccentric contraction and co-contraction of muscles and aids in the improvement of joint stability. Kwon YJ et al., 2013  stated in their study comparing the effects of open and closed kinetic chain exercises, a 5-year prospective RCT that both open and closed kinetic chain exercises are equally beneficial for long-term good functionality. They used IRM for the progression of weights with a predetermined or fixed number of sets and repetitions. Similarly, many authors designed a protocol with predetermined progression. This can raise questions about a patient’s comfort levels. Thus, we wanted to design the exercise protocol based on the sessional rating of perceived exertion (RPE) and progress accordingly. To our knowledge, this is the first study to use RPE for the progression of resistance in kinetic chain exercises for patellofemoral pain.