Continued Activity During Rehabilitation in Patients With Patellar Tendinopathy

This pilot study will evaluate the feasibility of pain-guided activity modification during rehabilitation for patellar tendinopathy. The information provided will be utilized to conduct a larger randomized clinical trial to determine if there is a difference in recovery from patellar tendinopathy during rehabilitation between individuals that use pain-guided activity modification and those that halt all painful activities. Recovery from patellar tendinopathy will be assessed using pain ratings, tendon-specific outcome measures, tendon structure, tendon mechanical properties, and muscle function.

Patellar tendinopathy is a chronic, degenerative condition of the patellar tendon that results in pain, altered tendon structure, functional impairments, decreased sports performance, and lost playing time. It commonly affects jumping athletes in sports such as volleyball and basketball. The prevalence of patellar tendinopathy is high, with 11.8-14.4% of recreational and 32-45% of elite volleyball and basketball players reporting symptoms. Although many athletes will seek treatment, 27-49% will experience re-injury and over half of those injured will retire from their sport of choice due to recurrent symptoms. Additionally, the absence of symptoms does not ensure full recovery of tendon health and function, which may contribute to the high rates of recurrence. Exercise therapy for the treatment of patellar tendinopathy is supported by the highest level of evidence. However, exercise therapy has been found to be ineffective if the patients continue with full sports participation. On the other hand, it is unclear if it is necessary for athletes to completely halt physical activities while undergoing treatment. Absence from sport due to injury has been associated with increased anxiety, depression, and decreased self-esteem. Therefore, it is of interest to maintain sports participation, as long as it does not interfere with injury recovery. In a randomized controlled trial (RCT) the investigators evaluated if continued running and jumping during treatment with an Achilles tendon-loading strengthening program had an effect on the outcome in patients with Achilles tendinopathy. In this study the investigators found that there were no detrimental effects of being physically active when the level of activity was guided by a pain-monitoring model. However, the impact of pain-guided activity modification has not been investigated in patellar tendinopathy. The proposed pilot study will determine if continued activity, using a pain-monitoring model, is feasible during treatment for patients with patellar tendinopathy. Furthermore, the investigators will evaluate if there is a negative effect on recovery of symptoms, tendon structure and mechanical properties, and functional recovery when adding continued physical activity compared to rest during exercise therapy treatment. To achieve this objective, the investigators will conduct a RCT comparing patients with patellar tendinopathy that are allowed to continue sports participation during treatment, using a pain-monitoring model, to those that are not allowed to participate in activities that cause pain. Aim 1 is to evaluate feasibility by examining compliance and satisfaction with continued sports participation, guided by a pain-monitoring model, compared to refraining from sports participation during treatment. This will provide critical information to determine if a larger randomized clinical trial is feasible and if the study protocol needs to be modified. Aim 2 is to evaluate if there is a difference in change over time in symptoms, tendon structure and mechanical properties, and function between the two interventions. This study will be the first to evaluate continued sports participation, guided by a pain-monitoring model, during rehabilitation in patients with patellar tendinopathy. The results from this study will play a critical role in achieving the long-term research goal of understanding of how to develop tailored treatments for patients with tendon injury. Ultimately this work will inform clinician recommendations regarding activity modification and potentially, limit the negative psychosocial impacts of the injury.

Participants in the Pain guided Activity Modification group will receive an exercise program consisting of progressive patellar tendon loading exercises Outside of physical therapy treatment, these participants will modify activity based on the Pain-Monitoring Model.

Participants in the Pain-free Activity Modification group will receive an identical exercise program to the Pain-guided Activity Modification group. However, participants will not be allowed to participate in activities that cause patellar tendon pain or excessively load the patellar tendon (e.g. jumping) outside of physical therapy treatment.

Exercise treatment will consist of squatting and knee extension exercises, designed to progressively load the patellar tendon (Heavy-Slow Resistance protocol). A pain-monitoring model is used to guide exercise loads. As the protocol progresses, exercise load is increased while repetitions are decreased.

Participants sports participation and physical activity will be guided by the Pain-Monitoring Model. Using the Pain-Monitoring Model, patients may participate in activities that cause patellar tendon pain, as long as pain does not exceed 5/10 on the numeric pain rating scale (NPRS) (0 = No pain, 10 = Worst pain imaginable) during or immediately after activity. Additionally, pain should return to pre-activity levels by the following morning and pain should not increase from week-to-week.

The percentage of potential participants that are willing to enroll and be randomized to one of the two groups after being informed of the study

Continuous shear wave elastography (cSWE) will be used to measure shear modulus, viscosity and dynamic shear modulus of the patellar tendon.

The Knee Injury and Osteoarthritis Outcome Score - Quality of Life subscale (KOOS-QOL) will be used to assess the impact of knee injury on quality of life. The KOOS-QOL is a subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS). Scores range from 0 to 100 with 0 indicating extreme detrimental effect on quality of life and 100 indicating no effect on quality of life.

The Tampa Scale of Kinesiophobia (TSK) will be used to measure participants fear of movement and re-injury (kinesiophobia). Scores on the TSK range from 17 to 68 with 17 indicating minimal to no fear of movement and re-injury and 68 indicating very high fear of movement and re-injury.

The Pain Catastrophizing Scale (PCS) will be used to assess patients pain catastrophizing. Scores on the PCS range from 0 to 52 with 0 indicating no pain catastrophizing and 52 indicating high levels of pain catastrophizing.

Patellar tendon pain will be assessed using the numeric pain rating scale. Participants are asked to verbally rate their pain on a scale of 0 to 10 with 0 indicating "No pain at all" and 10 indicating the "Worst pain imaginable".

Participant's depression, anxiety and stress levels will be assessed using the Depression, Anxiety and Stress Scale (DASS-21). The DASS-21 consists of three subscales, (1) Depression, (2) Anxiety, and (3) Stress. Scores for each subscale range form 0 to 42, where 0 indicates normal levels of the measured trait (depression, anxiety or stress) and 42 indicates extremely severe levels of the measured trait.

Inclusion Criteria: Physically active individuals with a diagnosis of patellar tendinopathy Exclusion Criteria: Injury that limits ability to participate in testing History of knee surgery within the last 6 months. Injection, shockwave, tenotomy or Ten-X to the patellar tendon within the last 6 months.

Sprague AL, Couppe C, Pohlig RT, Snyder-Mackler L, Silbernagel KG. Pain-guided activity modification during treatment for patellar tendinopathy: a feasibility and pilot randomized clinical trial. Pilot Feasibility Stud. 2021 Feb 25;7(1):58. doi: 10.1186/s40814-021-00792-5.