Abbott, J., Chapple, C., Fitzgerald, G., Fritz, J., Childs, J., Harcombe, H., & Stout, K., JOSPT. 2015; 45(12): 975-983. Article summary by Austin Gibbs SPT, from Missouri State University, Springfield, Missouri

This randomized clinical trial investigated the difference between four intervention groups for the treatment of knee osteoarthritis: exercise therapy without booster sessions, exercise therapy with booster sessions, exercise therapy plus manual therapy with no booster sessions, or exercise therapy plus manual therapy with booster sessions.  Booster sessions were defined as “sessions of supervised therapy provided at time intervals separated from the consecutive sessions of the initial episode of care, with intervening periods of no supervised therapy provision”.  In particular, the investigators sought to “investigate the effects of manual therapy combined with exercise therapy, compared with exercise therapy alone, in improving pain, disability, and physical function; and to compare the effects of delivering the physical therapy intervention using periodic booster sessions versus not using booster sessions in improving pain, disability, and physical function at 1-year follow-up”.

The participants in this study consisted of three primary sources: patients with knee pain attending physical therapy, patients referred for orthopedic consultation for knee osteoarthritis and not eligible for a joint replacement, and people with knee osteoarthritis on the researcher’s clinical trials mailing list.

Screening by a research nurse for inclusion and exclusion criteria with each participant was performed via a chart review and telephone interview. Inclusion criteria included age greater than 40 years and meeting the American College of Rheumatology clinical criteria for a diagnosis of knee osteoarthritis. Exclusion criteria was: rheumatoid arthritis, previous knee or hip joint replacement surgery of the affected joint, any other surgical procedure on the lower limbs in the previous six months, initiation of opioid or analgesic injection intervention for hip or knee pain within the previous 30 days, physical impairments unrelated to the hip or knee that would prevent safe participation in exercise, manual therapy, walking, or stationary cycling, inability to comprehend and complete study assessments or comply with study instructions, and/or stated inability to attend or complete the proposed course of intervention and follow up schedule.

Baseline testing and outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score which assesses pain, stiffness, and function for individuals with knee osteoarthritis, the numeric pain rating scale, timed-up-and-go test, the 30-second sit-to-stand test, and the 40-meter fast-paced walk test, and all assessors were blinded as to the participants randomly assigned group. However, secondary to the nature of the interventions, blinding of the treatment providers was not possible.

All participants were provided twelve 45-minute sessions of progressive exercise therapy with supervision from a licensed physical therapist. Each separate intervention group had mandatory interventions to be performed.

Description of Intervention Conditions

The no-booster condition received 12 consecutive sessions of their assigned intervention in the first 9 weeks of the study and the booster condition received 8 consecutive sessions in the first 9 weeks, 2 booster sessions at 5 months, and 1 booster session at 11 months. In the no-booster manual therapy condition, participants were provided twelve 30-45 minute sessions of manual therapy in addition to the exercise therapy sessions and the booster manual therapy condition received both the exercise intervention in addition to manual therapy in the first 9 weeks with 2 booster sessions at 5 months, and 1 booster session at 11 months.


Sixty-six participants from the original sample of 75 were retained at the 1-year follow up. This study concluded that provision of either manual therapy or booster sessions, in addition to exercise therapy, yielded incremental benefits when compared to providing traditional exercise therapy alone. Provision of manual therapy and booster sessions in addition to exercise, however, demonstrated a diminished effect in this combined group. The investigators for this study note that these findings are conflicting with earlier studies regarding the effectiveness of combined manual therapy in addition to exercise therapy for knee osteoarthritis (2,3,4,5). However, these findings are parallel with those of a recent report that found exercise therapy and manual therapy in conjunction with each other was more effective than that of traditional care by itself. (6) The authors propose that additional research is needed, as these results are conflicting with a similar study performed by Bennell et al, who found that 2 booster sessions did not influence pain or physical function outcomes in patients with knee osteoarthritis.

Overall, the investigators found that implementing manual therapy in conjunction with exercise therapy sessions, or spreading out exercise therapy treatment sessions over a year can enhance the efficacy of treatments for patients with regards to when compared to 12 consecutive exercise therapy sessions only.

Personal Commentary

As the growing demographics of persons over the age of 65 increases, and the prevalence of osteoarthritis increases, a need for research such as this from Abbott et. al. is more than necessary. It is apparent that there is conflicting literature regarding optimal care for patients with knee osteoarthritis. The booster session approach is interesting to ponder, as in my limited clinical experience these types of sessions have been non-existent. As many people have “regular” six month check ups with dentists and primary care physicians, one might conclude that this approach could potentially better serve our patients and perhaps maintain the efficacy of our treatment goals longer. Additionally, given the many different treatment options, it is my belief that the type of intervention to be implemented is dependent upon patient characteristics, presentation, and pathoanatomical differences from patient to patient. Continued literature such as this, however, can only help to better provide us with a framework for the performance of evidence guided practice and increase the probability of success for our patients.

  1. Fransen, M., McConnell, S., Harmer, A. R., Van der Esch, M., Simic, M., & Bennell, K. L. (2015). Exercise for osteoarthritis of the knee. Cochrane Database Syst Rev, 1.
  2. Deyle GD, Allison SC, Matekel RL, et al. Physical therapy treatment effectiveness for osteoarthritis of the knee: a randomized comparison of supervised clinical exercise and manual therapy procedures versus a home exercise program. Phys Ther. 2005;85:1301-1317.
  3. French HP, Brennan A, White B, Cusack T. Manu- al therapy for osteoarthritis of the hip or knee – a systematic review. Man Ther. 2011;16:109-117.
  4. Jamtvedt G, Dahm KT, Christie A, et al. Physical therapy interventions for patients with osteo- arthritis of the knee: an overview of systematic reviews. Phys Ther. 2008;88:123-136. http://
  5. Altman RD. Criteria for classi cation of clinical osteoarthritis. J Rheumatol Suppl. 1991;27:10-12.
  6. Abbott JH, Robertson MC, Chapple C, et al. Manual therapy, exercise therapy, or both, in addition to usual care, for osteoarthritis of the hip or knee: a randomized controlled trial. 1: clinical effectiveness. Osteoarthritis Cartilage. 2013;21:525-534. joca.2012.12.014