Abstract
Context:
Patellofemoral pain syndrome (PFPS) is associated with muscle imbalance at the knee and hip. Therapeutic exercise is effective at reducing pain associated with PFPS.
Objective:
To identify and analyze clinical trials of elastic resistance in patients with PFPS to determine its efficacy.
Data Sources:
PubMed, CINAHL, and PEDro databases were searched for terms relevant to PFPS rehabilitation in patients aged 12 to 40 years.
Study Selection:
Only peer-reviewed clinical trials lasting at least 4 weeks and specifying the use of elastic resistance in their protocols were included.
Data Extraction:
Eight eligible studies were analyzed for design, sample, intervention, outcomes, and clinical application.
Results:
The studies included in this review lacked high-quality design, often using exercise as a “quasi-control” condition. Most studies did not provide specific exercise prescription or progression. Although participants in each study reported significant improvements in pain, deficiencies in scientific design limit the conclusion.
Conclusion:
Elastic resistance exercise may reduce pain and improve function and strength in patients with PFPS.
Keywords: patellofemoral pain, elastic resistance, therapeutic exercise
Patellofemoral pain syndrome (PFPS) is characterized by retropatellar or peripatellar pain with walking, running, ascending or descending stairs, squatting, or prolonged sitting. The cause of PFPS remains unclear, although it is typically associated with muscle imbalances. Females are twice as likely as males to develop PFPS.4
Traditionally, PFPS was thought to result from weakness of the vastus medialis muscle, theoretically creating a more laterally tracking patella. The flexibility of the hamstrings, quadriceps, and gastroc/soleus complex has been associated with PFPS.18,24,26 Researchers have suggested that PFPS is related to muscular weakness at the hip, causing lateral patellar tracking caused by poor eccentric strength and control of hip abductors and external rotators.14,23 Females appear to be predisposed to proximal influences more so than males.19
Elastic resistance exercises are commonly prescribed for rehabilitation17 in osteoarthritis,16,22 total knee replacement,21 anterior cruciate ligament reconstruction,5 and as part of a multimodal approach to PFPS.2 Despite the widespread clinical application of elastic resistance exercise, few studies have investigated its efficacy in treating PFPS. The purpose of this systematic review is to analyze clinical trials of elastic resistance in PFPS.
Methods
Data Sources and Extraction
An online search of 3 databases (PubMed, CINAHL, and PEDro) was performed in August 2010 for studies published since 1970. Search terms included patellofemoral, rehabilitation, exercise, knee pain, Thera-hand, and elastic in a variety of combinations. Studies of knee osteoarthritis, Osgood-Schlatter disease, patella tendonitis/tendinosis, patella dislocation, plica, and meniscus were excluded. Clinical trials greater than 4 weeks in length were scanned for the use of elastic resistance in the protocol. The study design, sample, intervention, outcomes, and clinical implications were reviewed (Table 1). In addition, PEDro scores (http://www.pedro.org.au), where available, were determined (Table 2).
Table 1.
Clinical exercise trials for patellofemoral pain syndrome (PFPS) using elastic resistance.a
| Study: Design and Sample | Intervention /Elastic Exercises | Outcomes | Implications |
|---|---|---|---|
| Bily et al3 | |||
| Randomized, quasi control, prospective; n = 38, bilateral PFPS | 3 months, 2 groups Group 1: Supervised physical therapy (Thomee20 protocol) Group 2: Supervised physical therapy + electrical stimulation Both groups performed 4 direction kicks with tubing. Specified elastic resistance intensity and progression |
↓ Pain,* both groups ↑ Functional score,* both groups Strength, no significant difference, both groups No significant difference between groups |
Supervised physical therapy including elastic resistance effective at reducing pain and improving function without increasing strength; electrical stimulation provides no additional benefit |
| Doucette and Goble7 | |||
| Pretest/posttest, retrospective; n = 28, lateral patellar compression syndrome | Avg: 8-week treatment Individualized, not standardized Tubing exercises included seated leg press, single and double dips, resisted walking, knee flexion/extension. No specific prescription or progression of elastic exercises |
84% pain-free | Individualized physical therapy program including elastic resistance eliminated pain in 84% of PFPS patients; cause and effect cannot be established because of design |
| Eng et al8 | |||
| Randomized, quasi control, prospective; n = 20 young females, PFPS and poor foot biomechanics | 8 weeks, 2 groups Group 1: Exercise Group 2: Exercise + orthotics Both groups progressed to straight leg raise exercise with weights or elastic looped around ankles; no specific prescription or progression of elastic exercises |
↓ Pain* both groups Exercise + orthotics = significantly more improvement |
Exercise including elastic resistance significantly decreased pain in young females with PFPS; when elastic resistance is combined with orthotics, the reduction is significantly greater |
| Harrison et al9 | |||
| Randomized, quasi control, prospective; n = 113, PFPS | 1 month, 3 groups Group 1: Home exercise program Group 2: Exercise + manual therapy Group 3: Exercise + taping and biofeedback All groups suggested to use tubing hip adduction exercise; no specific prescription or progression of elastic exercises |
↓ Pain,* all groups at 12 months ↑ Clinical score,* all groups at 12 months ↑ Function,* all groups at 12 months Taping and biofeedback more effective than exercise and manual therapy at 1 month |
Home exercise including elastic resistance exercise effective at reducing pain and improving function over long term; short-term relief better when exercise combined with patellar taping and biofeedback |
| Kettunen et al11 | |||
| Randomized, quasi control, prospective; n = 56, chronic PFPS | 8 weeks, 2 groups Group 1: Home exercise program Group 2: Home exercise program + arthroscopic surgery Both groups performed elastic band kicks, leg pulls, and terminal knee extension; no specific prescription or progression of elastic resistance intensity levels (only repetitions are provided) |
↓ Pain,* both groups ↑ Functional score,* both groups ↑ Cost,* surgical group |
Home exercise program including elastic resistance exercise is effective at reducing pain and improving outcomes in PFPS; arthroscopic surgery provides no additional benefit and significantly increases health care costs compared with a home exercise program alone |
| Loudon et al13 | |||
| Quasi randomized, pretest/posttest, controlled, prospective; n = 29, PFPS | 8 weeks, 3 groups Group 1: Home exercise program Group 2: physical therapy clinic exercise Group 3: Control Both exercise groups performed elastic knee curls; no specific prescription or progression of elastic resistance intensity levels (only repetitions are provided) |
↓ Pain,* both exercise groups ↑ Strength* and functional score,* both exercise groups ↓ Pain* in physical therapy group compared to home exercise group |
Both home exercise and supervised physical therapy exercises including elastic resistance decrease pain and improve function and strength |
| Nakagawa et al15 | |||
| Randomized, quasi control, prospective; n = 14, PFPS | 6 weeks, 2 groups, home exercise program Group 1: Quad exercises Group 2: Quad + hip exercises Group 2 included hip rotation, trunk stabilization, and lunges with elastic resistance |
↓ Pain,* group 2 ↑ Muscle activation,* group 2 ↑ Knee strength,* both exercise groups Hip strength, no significant difference, both groups |
Additional hip exercises including elastic resistance are more effective at reducing pain in PFPS compared with knee exercise alone, without an increase in hip strength; however, sample size was small |
| Thomee20 | |||
| Randomized, prospective, no control; n = 40 females, PFPS | 12 weeks Group 1: Isometric exercise (elastic) Group 2: Eccentric exercise Isometric group performed 4-direction elastic band kicks on both legs. Specified elastic resistance intensity and progression |
85% pain-free across all participants ↓ Pain,* both groups ↑ Strength,* both groups |
Both eccentric and isometric exercise including elastic resistance reduced pain and improved strength in females with PFPS; however, cause and effect cannot be established, because no control group was included |
Statistically significant.
Table 2.
PEDro scores from clinical trials using elastic resistance to treat patellofemoral pain syndrome.
| PEDro Attribute | Bily et al3 | Doucette and Goble7 | Eng et al8 | Harrison et al9 | Kettunen et al11 | Loudon et al13 | Nakagawa et al15 | Thomee20 |
|---|---|---|---|---|---|---|---|---|
| Random allocation | • | • | • | • | • | |||
| Concealed allocation | • | • | • | |||||
| Baseline comparability | • | • | • | • | • | • | ||
| Blind subjects | ||||||||
| Eligibility criteriaa | • | • | • | |||||
| Blind therapist | ||||||||
| Blind assessor | • | • | ||||||
| Adequate follow-up | • | • | • | |||||
| Intention-to-treat analysis | • | • | • | |||||
| Between-group comparison | • | • | • | • | • | • | ||
| Point estimates and variability | • | • | • | • | • | • | ||
| Total PEDro score | 5 | NA | 3 | 5 | 7 | 2 | 7 | 5 |
Not factored into total score.
Results
Eight clinical studies met the criteria for this review.
Study Design
Seven studies were randomized prospective studies; 1 was retrospective.7 Only 1 study13 used a nonexercising control group. Most studies used a “quasi-control” design: The exercise group was the control limiting the conclusions (Table 2). Two studies received PEDro scores of 7 (out of 10),11,15 generally limited by blinding of raters and subjects.
Sample
All but 1 study15 had 20 or more participants. Adequate power was found in 3 studies.3,11,20 The analyzed studies had similar inclusion and exclusion criteria. One study7 investigated patients with “lateral patellar compression syndrome,” with diagnostic criteria similar to PFPS. Most samples included both males and females, although all studies had a greater number of females, representative of the PFPS population.
Intervention
All interventions lasted 4 to 12 weeks, with most lasting 8 weeks. Only 2 studies specified the intensity and volume of the elastic resistance exercise progression.3,20 Overall, well-defined protocols with elastic resistance exercises were lacking, limiting the replication or clinical application of the study and threatening external validity. Most studies combined multiple modes of exercise within groups, such as stretching, balance, and cardiovascular exercise, precluding analysis of exercise mode effectiveness. Elastic exercise was separately evaluated in 2 studies.15,20 Thomee20 found no difference between the elastic and isotonic groups. Nakagawa15 noted some additional benefit to adding specific elastic resistance exercises for the hip.
Two studies on healthy participants showed that elastic resistance exercises are as effective as isotonic resistance exercises for muscle activation and improving strength.1,6 Adding elastic resistance to terminal knee extension exercise significantly increases vastus medialis obliquis and vastus lateralis activity.25 Hopkins et al10 analyzed leg pulls with surface electromyogram, noting higher levels of vastus medialis activity.11
Outcomes
All studies reported significant reduction in pain regardless of the exercise intervention. Electrical stimulation, orthotics, patellar taping, biofeedback, and arthroscopic surgery had little to no additional benefit. Four studies assessed functional outcomes,3,9,11,13 reporting significant improvements over time without between-group differences. Three studies11,13,20 found significant improvements in strength, whereas 1 study did not.3 One study15 found improvements in quadriceps strength but not at the hip.
Discussion
Elastic resistance exercise appears to be as effective as other modes of resistance for PFPS. Electromyogram studies have confirmed that elastic resistance is comparable to isotonic exercise.1,6
The overall lack of blinding and suitable control groups reduces the ability to detect differences based on elastic resistance alone. Unfortunately, none of the reviewed studies used isolated elastic resistance exercise as an independent variable in PFPS interventions.
The cause of PFPS is not well established; patients may exhibit different impairments (ie, hip weakness versus knee weakness). Stratification by impairment may help improve clinical decision making for therapeutic exercise prescription. A systematic review of females with PFPS showed hip weakness, indicating strong evidence for decreased strength in hip external rotation, abduction, and extension compared with controls.27 Eccentric hip abduction and adduction are weaker in females with PFPS, whereas rotation strength appears normal.12
Conclusion
In summary, exercise interventions including elastic resistance in patients with PFPS are effective at reducing pain and improving function and strength.
Footnotes
One or more of the authors has declared a potential conflict of interest: Dr Page is employed by the Hygenic Corporation, which manufactures Thera-Band elastic resistance.
References
- 1. Andersen LL, Andersen CH, Mortensen OS, Poulsen OM, Bjornlund IB, Zebis MK. Muscle activation and perceived loading during rehabilitation exercises: comparison of dumbbells and elastic resistance. Phys Ther. 2010;90(4):538-549 [DOI] [PubMed] [Google Scholar]
- 2. Bhave A, Baker E. Prescribing quality patellofemoral rehabilitation before advocating operative care. Orthop Clin North Am. 2008;39(3):275-285 [DOI] [PubMed] [Google Scholar]
- 3. Bily W, Trimmel L, Modlin M, Kaider A, Kern H. Training program and additional electric muscle stimulation for patellofemoral pain syndrome: a pilot study. Arch Phys Med Rehabil. 2008;89(7):1230-1236 [DOI] [PubMed] [Google Scholar]
- 4. Boling M, Padua D, Marshall S, Guskiewicz K, Pyne S, Beutler A. Gender differences in the incidence and prevalence of patellofemoral pain syndrome. Scand J Med Sci Sports. 2010;20(5):725-730 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5. Bynum EB, Barrack RL, Alexander AH. Open versus closed chain kinetic exercises after anterior cruciate ligament reconstruction: a prospective randomized study. Am J Sports Med. 1995;23(4):401-406 [DOI] [PubMed] [Google Scholar]
- 6. Colado JC, Triplett NT. Effects of a short-term resistance program using elastic bands versus weight machines for sedentary middle-aged women. J Strength Cond Res. 2008;22(5):1441-1448 [DOI] [PubMed] [Google Scholar]
- 7. Doucette SA, Goble EM. The effect of exercise on patellar tracking in lateral patellar compression syndrome. Am J Sports Med. 1992;20(4):434-440 [DOI] [PubMed] [Google Scholar]
- 8. Eng JJ, Pierrynowski MR. Evaluation of soft foot orthotics in the treatment of patellofemoral pain syndrome. Phys Ther. 1993;73(2):62-68 [DOI] [PubMed] [Google Scholar]
- 9. Harrison EL, Sheppard MS, McQuarrie AM. A randomized controlled trial of physical therapy treatment programs in patellofemoral pain syndrome. Physiother Can. 1999;51(2):93-100 [Google Scholar]
- 10. Hopkins JT, Ingersoll CD, Sandrey MA, Bleggi SD. An electromyographic comparison of 4 closed chain exercises. J Athl Train. 1999;34(4):353-357 [PMC free article] [PubMed] [Google Scholar]
- 11. Kettunen J, Harilainen A, Sandelin J, et al. Knee arthroscopy and exercise versus exercise only for chronic patellofemoral pain syndrome: a randomized controlled trial. BMC Med. 2007;5(1):38. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12. Long-Rossi F, Salsich GB. Pain and hip lateral rotator muscle strength contribute to functional status in females with patellofemoral pain. Physiother Res Int. 2010;15(1):57-64 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13. Loudon JK, Gajewski B, Goist-Foley HL, Loudon KL. The effectiveness of exercise in treating patellofemoral-pain syndrome. J Sport Rehabil. 2004;13:323-342 [Google Scholar]
- 14. Mascal CL, Landel R, Powers C. Management of patellofemoral pain targeting hip, pelvis, and trunk muscle function: 2 case reports. J Orthop Sports Phys Ther. 2003;33(11):647-660 [DOI] [PubMed] [Google Scholar]
- 15. Nakagawa TH, Muniz TB, Baldon Rde M, Dias Maciel C, de Menezes Reiff RB, Serrao FV. The effect of additional strengthening of hip abductor and lateral rotator muscles in patellofemoral pain syndrome: a randomized controlled pilot study. Clin Rehabil. 2008;22(12):1051-1060 [DOI] [PubMed] [Google Scholar]
- 16. O’Reilly SC, Muir KR, Doherty M. Effectiveness of home exercise on pain and disability from osteoarthritis of the knee: a randomised controlled trial. Ann Rheum Dis. 1999;58(1):15-19 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17. Page P. A survey of decision-making and utilization of elastic resistance among rehabilitation professionals [abstract]. J Orthop Sports Phys Ther. 2004;33(2):A61-A62 [Google Scholar]
- 18. Piva SR, Goodnite EA, Childs JD. Strength around the hip and flexibility of soft tissues in individuals with and without patellofemoral pain syndrome. J Orthop Sports Phys Ther. 2005;35(12):793-801 [DOI] [PubMed] [Google Scholar]
- 19. Powers CM. The influence of abnormal hip mechanics on knee injury: a biomechanical perspective. J Orthop Sports Phys Ther. 2010;40(2):42-51 [DOI] [PubMed] [Google Scholar]
- 20. Thomee R. A comprehensive treatment approach for patellofemoral pain syndrome in young women. Phys Ther. 1997;77(12):1690-1703 [DOI] [PubMed] [Google Scholar]
- 21. Topp R, Swank AM, Quesada PM, Nyland J, Malkani A. The effect of prehabilitation exercise on strength and functioning after total knee arthroplasty. Phys Med Rehabil. 2009;1(8):729-735 [DOI] [PubMed] [Google Scholar]
- 22. Topp R, Woolley S, Hornyak J, 3rd, Khuder S, Kahaleh B. The effect of dynamic versus isometric resistance training on pain and functioning among adults with osteoarthritis of the knee. Arch Phys Med Rehabil. 2002;83(9):1187-1195 [DOI] [PubMed] [Google Scholar]
- 23. Tyler TF, Nicholas SJ, Mullaney MJ, McHugh MP. The role of hip muscle function in the treatment of patellofemoral pain syndrome. Am J Sports Med. 2006;34(4):630-636 [DOI] [PubMed] [Google Scholar]
- 24. White LC, Dolphin P, Dixon J. Hamstring length in patellofemoral pain syndrome. Physiotherapy. 2009;95(1):24-28 [DOI] [PubMed] [Google Scholar]
- 25. Willett GM, Paladino JB, Barr KM, Korta JN, Karst GM. Medial and lateral quadriceps muscle activity during weight-bearing knee extension exercise. J Sport Rehabil. 1998;7:248-257 [Google Scholar]
- 26. Witvrouw E, Lysens R, Bellemans J, Cambier D, Vanderstraeten G. Intrinsic risk factors for the development of anterior knee pain in an athletic population: a two-year prospective study. Am J Sports Med. 2000;28(4):480-489 [DOI] [PubMed] [Google Scholar]
- 27. Prins MR, van der Wurff P. Females with patellofemoral pain syndrome have weak hip muscles: a systematic review. Aust J Physiother. 2009;55(1):9-15 [DOI] [PubMed] [Google Scholar]