MAPS: Maitland-Australian homecontact us
find us on facebook find us on linkedin

Robert J. Fluegel, PT, COMT
MAPS Faculty, Fellow in Training, MAPS Orthopedic Manual Therapy Fellowship

Chris R. Showalter, PT, OCS, COMT, FAAOMPT, Fellowship Program Director

Mobilization combined with Stabilization is SUPERIOR compared to Stabilization alone in Non-Specific Mechanical Neck Pain (NSMNP)

sign up for email updates from MAPS

Can isolating the VMO assist with rehabilitation of Patello-Femoral Pain Syndrome?

June 15, 2017

Research Commentary

Travis H. Stoner, PT, DPT, COMT
Fellow in Training…MAPS Fellowship in Orthopedic Manual Therapy

Chris R. Showalter PT, COMT, OCS, FAAOMPT
Fellowship Program Director


Can isolating the VMO assist with rehabilitation of Patello-Femoral Pain Syndrome?

Patello-femoral pain syndrome (PFPS) is a clinical diagnosis commonly encountered by many physical therapists, accounting for over 7% of orthopedic physician visits (Glaviano, et al. 2015) based upon ICD-9 reporting, and between 11-17% of all knee pain seen by general practitioners (Crossley et al 2015).  Given the high incidence of PFPS, it is important that physical therapists develop valid treatment strategies to properly treat patients with this condition through appropriate and thorough evaluations, using both evidence-based research and clinical reasoning. 

A common PFPS clinical finding is lateral tracking of the patella – suspected to be a significant cause of anterior knee pain

Therapeutic exercises are often employed with the intention of isolating and improving motor control of the vastus medialis obliquus (VMO) component of the quadriceps muscle. These exercises are often performed as contractions of the quadriceps while the femur is placed into rotation to bias forces towards the medial side of the femur with the intention to enhance VMO activation. This strategy seems to be based upon a cadaver study conducted by Lieb and Perry (1968), who suggested that the primary focus of rehabilitation for lateral tracking patellae should involve VMO isolation exercises (due to the 55 degree angle of pull of the VMO medial to the midline of the femur), in contrast to the more vertical orientation of vastus lateralis (VL). Lieb and Perry (1968) suggested that an imbalance was present between the pull of the VMO compared to that of the VL, and thus a weak or inactivated VMO may be considered a primary contributing factor to PFPS.

But can we truly isolate the VMO?

Smith, et al, (2009) published a systematic review of EMG evidence to determine whether performing quadriceps exercises with co-contraction of other lower extremity muscle groups, or by altering lower limb position, can preferentially activate the VMO. The authors reviewed a total of 2,593 citations, using specific exclusion criteria, and found 20 separate studies to include in their review.  These 20 papers included 387 subjects, including 300 asymptomatic and 87 PFPS patients. The authors reviewed six different positions of the lower extremity and analyzed VMO activity, including:

1) Hip abduction/adduction

2) Tibial internal/external rotation

3) Hip internal/external rotation

4) combined tibial/femoral internal/external rotation

5) ankle dorsiflexion/plantarflexion

6) foot pronation/supination


The results of the Smith (2009) systematic review were as follows:

1.    Hip abduction-adduction: Eight studies were reviewed, one study (Hodges & Richardson, 1993) found that the addition of isometric hip adduction produced statistically significant increases in the VMO/VL ratio compared to the control group without hip adduction. The other seven studies concluded that there was no evidence of preferential VMO recruitment. Overall, there was limited evidence to support the idea that there can be preferential VMO activation through hip abduction or adduction.

2.    Hip internal/external rotation: Seven studies were analyzed, six of which found there was no significant preferential VMO activation based on this position.  One study (Lam & Ng 2001) did find that a “semi-squat” isometric knee extension contraction at 40 deg. knee flexion with 30 deg. hip internal rotation did demonstrate a significant difference in VMO/VL ratio compared to external rotation; however, there was no significant difference between internal rotation and neutral.

3.    Tibial internal/external rotation: Four studies assessed tibial position, three of which found no statically significant difference in relative VMO and VL activity levels. One study (Willis 2005) found greater VMO activation during cycling with tibial external rotation compared to placing the foot into tibial internal rotation to perform isometric knee extension. However, the authors only presented VMO/VL ratio data so the actual activation of the VMO was not presented.

4.    Combined tibial/femoral internal/external rotation: Two studies were reviewed, both of which found no statistically significant preferential VMO activation in symptomatic patients.  However, one study (Miller, et al 1997) did find increased VMO/VL activation in asymptomatic patients at 45 deg. combined tibial and femoral internal rotation compared to 45 deg. external rotation during step-ups, step-downs, and semi squats.  However, the Miller, et. al 1997 study found no significant difference when performing these exercises in neutral tibia and femoral rotation.  

5.    Ankle dorsiflexion/plantarflexion: Three studies were reviewed, all of which found no significant evidence that VMO activation increased based upon ankle positioning.

6.    Foot pronation/supination: Three studies were reviewed, two of which found no significant difference in supination or pronation. One study (Gregersen, et al 2006) found that the VMO/VL ratio was significantly different with pronation during cycling, however no EMG data was provided for detailed analysis of specific VMO activation.

Smith et al (2009) Systematic Review: Conclusion

The Smith et al. (2009) systematic review concluded: “we recommend that clinicians should not focus on VMO strengthening, in preference to general quadriceps training, when rehabilitating patients with patellofemoral disorders, because this may not be possible.”  The authors suggested caution in interpretation of the results and noted that the included studies demonstrated significant variations and limitations in methodology.   

…Smith et. al (2009) therefore suggests that the VMO cannot be preferentially activated.


Differences in VMO/VL activity in Leg Rotation between Symptomatic and Asymptomatic Individuals

Miller, Sedory, & Croce (1997) assessed leg rotation and VMO/VL EMG activity during closed-chain kinetic exercises, commonly prescribed specifically for patellofemoral pain. The authors evaluated 15 female athletes (6 symptomatic, 9 asymptomatic) performing step up/step down activities, and modified wall slide exercises and found that:

The results suggest that external rotation of the leg may affect VMO/VL activity ratio during closed chain knee extension exercises in individuals without PFPS but not in individuals symptomatic for PFPS”.

This is a particularly interesting finding, and raises several pertinent questions:

  • How common is lack of VMO activation in PFPS patients?
  • Is VMO inactivation potentially due to disuse, tracking anomalies, inhibition, and/or incoordination of contraction of VMO, and therefore, a valid reason to attempt to facilitate the VMO?


…Leg rotation therefore does preferentially activate the VMO in closed-chain exercises in asymptomatic individuals…but NOT in symptomatic individuals


Impact of Hip Rotation on VMO/VL Ratio in Asymptomatic Patients - Davlin et al (1999)

Davlin, Holcomb, & Guadagnoli (1999) also investigated the effects of hip rotation on VMO/VL ratio using EMG feedback over a five day period. The authors evaluated 36 asymptomatic females who performed specific exercises on three (3) consecutive days with a pre-test and post-test on the first (1st) and fifth (5th) day respectively.  The researchers had each subject perform six (6), five-second isometric contractions of the quadriceps in terminal extension, in hip IR, ER, and neutral on the pre-test and post-test days (days 1 and 5).  The training on days 2-4 consisted of randomizing the subjects into three training groups, namely:

1) maximal hip IR

2) maximal hip ER, and

3) neutral hip rotation. 

Each subject performed submaximal isometric contractions of the right quadriceps muscles for five sets of 5 contractions, holding 10 seconds each.  The authors found that each group was able to increase their VMO/VL activation, regardless of hip position. 

…There was no significant difference between neutral, IR, and ER of the hip to activate VMO, although training can increase the VMO:VL ratio in just 3 days.  The Davlin et al (1999) study also suggests that EMG feedback may be useful in quadriceps training.


Song et al (2009): Does Hip Adduction during seated leg press affect quadriceps hypertrophy?

Song, et al. (2009) investigated the effect of hip adduction during seated leg press exercise upon VMO in 89 symptomatic patients with patellofemoral pain syndrome. Participants were randomized to one of three groups, namely:

1) hip adduction combined with leg press

2) leg press alone, or

3) no exercise (control) 

Exercise training was conducted 3 times per week for 8 weeks (24 sessions) and measurement of VMO morphology was evaluated using ultrasonography.  The results indicated that:

·       There was no significant difference (p= 0.12) in VMO hypertrophy between the 2 exercise groups (leg press and leg press in hip adduction). 

·       Both exercise groups displayed significant (p <0.008) improvements in VMO hypertrophy compared to the control group.

·       The authors of Song et al (2009) concluded that incorporation of hip adduction has no effect on quadricep hypertrophy.

…There was no significant difference when adding hip adduction to leg press to preferentially activate VMO, however, 24 sessions of training resulted in significant (p <0.008) improvements in VMO volume.   


Does the VMO selectively atrophy in PFPS?

Giles et al. (2015) investigated the concept that VMO atrophy is present in patients with patellofemoral pain syndrome. The authors performed real time ultrasound on 70 participants, 35 with PFPS, 22 unilaterally and 13 bilaterally. The researchers found that the size of the entire quadriceps was significantly smaller (p=0.038 to p=0.045) in subjects with unilateral pain compared to the asymptomatic limb; however, there was no selective atrophy of the VMO compared to the VL or other quadricep musculature. The authors concluded that due to the superficial location of the bulk of the VMO, it is the easiest portion of the quadriceps to compare visually to the contralateral limb and is therefore often targeted by clinicians for visual confirmation of patient status. However, the entire quadriceps muscle is atrophied in patients with PFPS.

…There is no evidence to support selective atrophy of the VMO


Does VMO angle-of-pull correlate with degeneration of the patellofemoral joint?

Hubbard et al. (1998) investigated the relationship of VMO fiber angle in relation to degenerative changes of the patellofemoral joint. The authors dissected 374 cadaver lower extremities to analyze the morphology of the VMO in comparison with the degenerative changes of the patellofemoral joint. The authors found that the fascial planes of the VL proper were shared with the section of the muscle commonly referred to as the VMO, and as such, there is no anatomical or functional difference between these “two muscles” and we should abandon the idea that we can selectively isolate the VMO. The authors also found that there is there is no significant difference between the gender of the cadaver and the presence of patellofemoral joint disease or the angle of pull of the distal segment of VMO and the presence or severity of degeneration of the patellofemoral joint.

…There is no correlation between morphological differences in the VMO muscle body, muscle bulk, or angulation of the distal VMO fibers to degeneration of the patellofemoral joint.


Is the VMO anatomically different from the rest of VM?

Nozic, et al. (1997) compared the proximal and distal parts of the vastus medialis muscle (VM).  The researchers analyzed 50 cadavers aged 16-91 and sought to investigate two issues:

1) To determine if there is a significant difference in the alignment of proximal vs distal segment of the muscle and

2) To examine a potential division in the fascial plane between the proximal and distal segment of the VM

The study concluded that, “the vastus medialis muscle should not be classified as two separate muscles.”

…Although the vastus medialis does demonstrate some minor proximal and distal morphological differences, VM and VMO cannot be preferentially identified as different anatomical structures.


Does VMO morphology contribute to patellar dislocations?

Balcarek, et al. (2014) investigated the morphology of the VMO in relation to recurrent patella dislocations.  The researchers measured the VMO via MRI in the sagittal, coronal, and transverse plane to evaluate 24 patients, 8 with acute dislocation, 8 with recurrent dislocation, and 8 control subjects.  While the researchers found significant bony differences in the patients, there was no significant difference found “with respect to all measured VMO parameters between primary dislocation, recurrent dislocation, and the control group.”

…No correlation was found in morphology of the VMO and incidence of patella subluxation.



·       There is no evidence to support the idea that the VMO is anatomically or functionally different from the rest of the vastus medialis (VM).

·       There is limited evidence to support the concept that VMO can be specifically isolated based upon various lower limb angulation positions

·       Although the entire quadricep muscle does atrophy in patients with PFPS, the VMO does NOT seem to selectively atrophy compared to other muscles of the quadricep group.

·       VMO morphology does not seem to contribute to patellar dislocation

·       Just 3 sessions of global quadricep training improves VMO/VL ratios.

·       EMG biofeedback may be a valuable tool in the rehabilitation of the quadriceps in PFPS.



The research presented in this month's Research Commentary indicates that the entire quadriceps muscle syndrome. There is evidence that closed chain exercises such as step-ups, wall squats, leg press, and open chain exercises such as isometrics of the quadriceps do increase muscle bulk in symptomatic patients. EMG biofeedback may be a useful adjunctive tool to accomplish improved quadriceps fuction. 

However, the idea that we actually can, or even need to isolate the VMO to produce improved function is not fully supported in the literature.  Incorporating appropriate manual techniques as indicated by a thorough examination, and strengthening the quadriceps without adding co-contractions of other muscle groups is supported in the research to provide sufficient activation of the quadriceps.

The Maitland approach is the systematic application of a clinical reasoning thought process in the assessment and management of neuro-musculo-skeletal (NMS) complaints and the subsequent detailed assessment of subjective and objective clinical findings. “Comparable Sign” affords the therapist the opportunity to reliably identify “the site of the lesion”, which has clinical utility not just for treatment and recording, but also for communication between and with other professionals in order to provide effective management and care for the patient. Maitland-trained therapists are guided in this process through their thorough patient examination, use of clinical reasoning, and the response (and continuous reassessment) of the patient in the effective management of NMS complaints.

Cheers and Enjoy

Travis Stoner PT, DPT, COMT

Chris R. Showalter PT, OCS, COMT, FAAOMPT


© Maitland Australian Physiotherapy Seminars. Not to be reproduced, copied or retransmitted in any manner without MAPS express written permission. Directing others to the MAPS website ( is permissible.


Balcarek, P., Oberthür, S., Frosch, S., Schüttrumpf, J. P., & Stürmer, K. M. (2014). Vastus medialis obliquus muscle morphology in primary and recurrent lateral patellar instability. BioMed Research International, 2014, 326586. 
Crossley, K. M., Callaghan, M. J., & Linschoten, R. van. (2015). Patellofemoral pain. BMJ, 351, h3939.
Davlin, C. D., Holcomb, W. R., & Guadagnoli, M. A. (1999). The effect of hip position and electromyographic biofeedback training on the vastus medialis oblique: vastus lateralis ratio. Journal of Athletic Training, 34(4), 342–346. 

Giles, L. S., Webster, K. E., McClelland, J. A., & Cook, J. (2015). Atrophy of the Quadriceps Is Not Isolated to the Vastus Medialis Oblique in Individuals With Patellofemoral Pain. The Journal of Orthopaedic and Sports Physical Therapy, 45(8), 613–619.
Glaviano, N. R., Kew, M., Hart, J. M., & Saliba, S. (2015). DEMOGRAPHIC AND EPIDEMIOLOGICAL TRENDS IN PATELLOFEMORAL PAIN. International Journal of Sports Physical Therapy, 10(3), 281–290. 

Gregersen, C. S., Hull, M. L., & Hakansson, N. A. (2006). How changing the inversion/eversion foot angle affects the nondriving intersegmental knee moments and the relative activation of the vastii muscles in cycling. Journal of Biomechanical Engineering, 128(3), 391–398.
Hodges, P. W., & Richardson, C. A. (1993). The influence of isometric hip adduction on quadriceps femoris activity. Scandinavian Journal of Rehabilitation Medicine, 25(2), 57–62.

Hubbard, J. K., Sampson, H. W., & Elledge, J. R. (1998). The vastus medialis oblique muscle and its relationship to patellofemoral joint deterioration in human cadavers. The Journal of Orthopaedic and Sports Physical Therapy, 28(6), 384–391.
Lam, P. L., & Ng, G. Y. (2001). Activation of the quadriceps muscle during semisquatting with different hip and knee positions in patients with anterior knee pain. American Journal of Physical Medicine & Rehabilitation, 80(11), 804–808.
Lieb, F. J., & Perry, J. (1968). Quadriceps function. An anatomical and mechanical study using amputated limbs. The Journal of Bone and Joint Surgery. American Volume, 50(8), 1535–1548.
Miller, J. P., Sedory, D., & Croce, R. V. (1997). Leg rotation and vastus medialis oblique/vastus lateralis electromyogram activity ratio during closed chain kinetic exercises prescribed for patellofemoral pain. Journal of Athletic Training, 32(3), 216–220.
Nozic, M., Mitchell, J., & de Klerk, D. (1997). A comparison of the proximal and distal parts of the vastus medialis muscle. The Australian Journal of Physiotherapy, 43(4), 277–281.

Smith, T. O., Bowyer, D., Dixon, J., Stephenson, R., Chester, R., & Donell, S. T. (2009). Can vastus medialis oblique be preferentially activated? A systematic review of electromyographic studies. Physiotherapy Theory and Practice, 25(2), 69–98. 

Song, C.-Y., Lin, Y.-F., Wei, T.-C., Lin, D.-H., Yen, T.-Y., & Jan, M.-H. (2009). Surplus value of hip adduction in leg-press exercise in patients with patellofemoral pain syndrome: a randomized controlled trial. Physical Therapy, 89(5), 409–418. 

Willis, F. B., Burkhardt, E. J., Walker, J. E., Johnson, M. A., & Spears, T. D. (2005). Preferential vastus medialis oblique activation achieved as a treatment for knee disorders. Journal of Strength and Conditioning Research, 19(2), 286–291.

Back To Research Commentary
Find a COMT Course Schedule Course Descriptions Register for Courses Faculty
Looking for a COMT? This list of Certified Orthopedic Manual Therapists (or COMTs) includes all COMT graduates worldwide, as well as MAPS faculty. We suggest that you visit this page often to check course confirmation status and to find new courses which are added frequently. Our seminars incorporate the teaching of Geoff Maitland and others who have contributed to what has become known as the "Maitland-Australian Approach". Registering for classes is easy. Submit full payment with the registration form. Reservations are limited and are on a first come, first serve basis. Come meet our world-class faculty. Each of our faculty has experience in a wide variety of manual therapy practices and specialty areas.


© 2007 All rights reserved.