Effect of the Muscle Strength and Range of Motion Training for Post-platelet Rich Plasma Injection in People With Rotator Cuff Partial Tear: a Randomized, Cross-over Trial

Background:

Although it is known that Platelet-Rich Plasma injections have a remarkable pain relief effect for patients with partial tears of the rotator cuff in the shoulder joint, many patients still experience limited muscle strength and joint mobility recovery. Patients often inquire about post-Platelet-Rich Plasma injection rehabilitation and precautions. Therefore, it is necessary to design a comprehensive post-injection rehabilitation and training plan to improve the quality of treatment. However, previous literature on post-Platelet-Rich Plasma injection treatment seems to have inconsistent rehabilitation plans. One major reason for this inconsistency might be the lack of sufficient evidence or unclear rehabilitation effectiveness, leading to poor patient compliance. The underlying cause of these issues is the absence of a standardized and effective rehabilitation plan. Hence, it is essential to develop a standardized rehabilitation plan to enhance treatment effectiveness.

Method:

The investigators designed a non-blinded, randomized, crossover trial to observe the potential benefits of muscle strength and joint mobility rehabilitation intervention one month after PRP injection treatment for patients with partial tears of the rotator cuff. Patients were randomly divided into two groups. One group received only standard physical therapy (magneto-therapy, low-energy laser, electrotherapy, etc.), while the other group underwent muscle strength and joint mobility training in addition to standard physical therapy. There were three assessment time points: pre-assessment (one week after Platelet-Rich Plasma injection), after the first stage of treatment (three weeks of rehabilitation training + standard physical therapy/standard physical therapy following the first Platelet-Rich Plasma injection treatment), and after the second stage of treatment (three weeks of rehabilitation training + standard physical therapy/standard physical therapy following the second Platelet-Rich Plasma injection treatment).

The assessment methods included quantifying muscle strength using a hand-held dynamometer (Manual Muscle Test) and measuring three shoulder joint angles (abduction, external rotation, internal rotation). The Shoulder Pain and Disability Index recorded changes and progress in each value at different treatment stages.

Analysis: A repeated-measures Analysis of Variance model was used to analyze the trial's effects and correlations. We also analyzed whether the dose-effect existed concerning the use of time/frequency.