eMedicine Specialties > Physical Medicine and Rehabilitation > Lower Limb Musculoskeletal Conditions

Patellofemoral Syndrome: Differential Diagnoses & Workup

Author: Patrick J Potter, BSc, MD, FRCP(C), Associate Professor, Physical Medicine and Rehabilitation, The University of Western Ontario; Consulting Staff, Department of Physical Medicine and Rehabilitation, St Joseph's Health Care Centre
Coauthor(s): Keith AJ Sequeira, MD, Associate Director of Spinal Cord Medicine, Assistant Professor, Department of Physical Medicine and Rehabilitation, Parkwood Hospital, University of Western Ontario
Contributor Information and Disclosures

Updated: Jul 15, 2009

Differential Diagnoses

Patellofemoral Arthritis
Prepatellar Bursitis

Other Problems to Be Considered

Referred pain from hip
Osgood-Schlatter syndrome
Sindling-Larsen-Johansson syndrome
Neuroma
Patellar tendonitis
Plica syndromes of the anterior knee
Radicular pain
Infection of the knee joint
Tumor (eg, knee joint, femur)

Workup

Laboratory Studies

  • Laboratory studies generally are not indicated for the diagnosis of patellofemoral syndrome.

Imaging Studies

  • Imaging studies usually are not necessary in order for a physician to diagnose or recommend treatment for patellofemoral syndrome (PFS). Imaging studies should be considered for unusual presentations and for persons in whom the syndrome is refractory to conservative management.
    • Skyline views should be included with anterior-posterior (AP) and lateral radiographic imaging of the knee. Limited positions of flexion are available for such viewing. These radiographs provide more of an indirect observation of what is happening within the articulation.
    • Lateral patellar tilt and a high-riding patella (patella alta) may be observed.
    • Osteophytes or joint space narrowing may be identified, suggesting arthritic changes in the articular cartilage.3
  • Nuclear scans are less likely to be of value in defining PFS and are more useful in helping to identify other, less common conditions that may mimic PFS, as outlined in the differential diagnoses. When changes have occurred in the retropatellar cartilage, mild increases in uptake of radionucleotide may be observed. Increased uptake of radionucleotide is not limited to the patella; it may be seen in the proximal tibia, distal femur, or patella.4
  • Computed tomography (CT) scanning and magnetic resonance imaging (MRI)
    • CT scanning and MRI allow for imaging at various angles of flexion.
    • CT scanning with the knee in full extension has been demonstrated to more accurately detect patellar subluxation.
    • Cross-sectional viewing allows more direct visualization of the articulation between the patella and femur.
    • Schutzer et al identified 3 patterns of malalignment using CT scanning5 :
      • Type 1 includes patellar subluxation without tilt.
      • Type 2 is described as patellar subluxation with tilt.
      • Type 3 is patellar tilt without subluxation.

Other Tests

  • Serology, joint aspiration, and related tests are indicated only when alternative diagnoses are suspected. Such investigations are not likely to provide useful information in this syndrome, as it is not a disease entity but rather a group of symptoms occurring sometimes in association with multiple factors (intrinsic and extrinsic).6

Procedures

  • Arthroscopy
    • Arthroscopy helps to confirm the diagnosis patellofemoral syndrome (PFS) by allowing direct visualization of the cartilage surface. Arthroscopic evaluation also provides assessment of joint structures that may cause symptoms that mimic PFS when they are impaired.
    • Arthroscopy also has the ability to facilitate surgical alteration of patellar tracking (eg, lateral release). Visualization of the patella may allow for some revision of the cartilage surface. However, most authors agree that surgical treatment is rarely indicated.

Histologic Findings

Histologic findings are dependent on the extent to which the cartilage surfaces have been compromised. Shearing stresses may result in changes in subchondral bone and dysplasia of the cartilage surface. More severe cartilage changes have been identified in persons with patellofemoral syndrome that has been refractory to conservative measures.

More on Patellofemoral Syndrome

Overview: Patellofemoral Syndrome
Differential Diagnoses & Workup: Patellofemoral Syndrome
Treatment & Medication: Patellofemoral Syndrome
Follow-up: Patellofemoral Syndrome
References
Further Reading
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References

  1. Piva SR, Fitzgerald GK, Irrgang JJ, et al. Associates of physical function and pain in patients with patellofemoral pain syndrome. Arch Phys Med Rehabil. Feb 2009;90(2):285-95. [Medline].

  2. Price JL. Patellofemoral syndrome: how to perform a basic knee evaluation. JAAPA. Dec 2008;21(12):39-43. [Medline].

  3. Kettunen JA, Visuri T, Harilainen A, et al. Primary cartilage lesions and outcome among subjects with patellofemoral pain syndrome. Knee Surg Sports Traumatol Arthrosc. Mar 2005;13(2):131-4. [Medline].

  4. Naslund JE, Odenbring S, Naslund UB, et al. Diffusely increased bone scintigraphic uptake in patellofemoral pain syndrome. Br J Sports Med. Mar 2005;39(3):162-5. [Medline]. [Full Text].

  5. Schutzer SF, Ramsby GR, Fulkerson JP. Computed tomographic classification of patellofemoral pain patients. Orthop Clin North Am. Apr 1986;17(2):235-48. [Medline].

  6. Bolgla LA, Malone TR, Umberger BR, et al. Reliability of electromyographic methods used for assessing hip and knee neuromuscular activity in females diagnosed with patellofemoral pain syndrome. J Electromyogr Kinesiol. Jan 2 2009;[Medline].

  7. [Best Evidence] Syme G, Rowe P, Martin D, et al. Disability in patients with chronic patellofemoral pain syndrome: a randomised controlled trial of VMO selective training versus general quadriceps strengthening. Man Ther. Jun 2009;14(3):252-63. [Medline].

  8. [Best Evidence] Collins N, Crossley K, Beller E, et al. Foot orthoses and physiotherapy in the treatment of patellofemoral pain syndrome: randomised clinical trial. BMJ. Oct 24 2008;337:a1735. [Medline]. [Full Text].

  9. Teitge RA. Patellofemoral syndrome a paradigm for current surgical strategies. Orthop Clin North Am. Jul 2008;39(3):287-311, v. [Medline].

  10. Crossley K, Bennell K, Green S, et al. A systematic review of physical interventions for patellofemoral pain syndrome. Clin J Sport Med. Apr 2001;11(2):103-10. [Medline].

  11. Devan MR, Pescatello LS, Faghri P, et al. A prospective study of overuse knee injuries among female athletes with muscle imbalances and structural abnormalities. J Athl Train. 9 2004;39(3):263-7. [Medline]. [Full Text].

  12. Handelberg F, Shahabpour M, Van Betten F, et al. CT arthrography and MRI of the patella. Acta Orthop Belg. 1989;55(3):331-8. [Medline].

  13. Haut RC, Ide TM, De Camp CE. Mechanical responses of the rabbit patello-femoral joint to blunt impact. J Biomech Eng. Nov 1995;117(4):402-8. [Medline].

  14. Hope PG. Arthroscopy in children. J R Soc Med. Jan 1991;84(1):29-31. [Medline]. [Full Text].

  15. Imai N, Tomatsu T, Nakaseko J, et al. Clinical and roentgenological studies on malalignment disorders of the patello-femoral joint. Part II: relationship between predisposing factors and malalignment of the patello-femoral joint. Nippon Seikeigeka Gakkai Zasshi. Nov 1987;61(11):1191-202. [Medline].

  16. Johnston LB, Gross MT. Effects of foot orthoses on quality of life for individuals with patellofemoral pain syndrome. J Orthop Sports Phys Ther. Aug 2004;34(8):440-8. [Medline].

  17. Juhn MS. Patellofemoral pain syndrome: a review and guidelines for treatment [published erratum appears in Am Fam Physician 2000 Feb 15;61(4):960, 965]. Am Fam Physician. Nov 1 1999;60(7):2012-22. [Medline]. [Full Text].

  18. Karlsson J, Sward L, Lansinger O. Bad results after anterior advancement of the tibial tubercle for patello-femoral pain syndrome. Arch Orthop Trauma Surg. 1992;111(4):195-7. [Medline].

  19. Karlsson J, Thomee R, Sward L. Eleven year follow-up of patello-femoral pain syndrome. Clin J Sport Med. Jan 1996;6(1):22-6. [Medline].

  20. Kujala UM, Friberg O, Aalto T, et al. Lower limb asymmetry and patellofemoral joint incongruence in the etiology of knee exertion injuries in athletes. Int J Sports Med. Jun 1987;8(3):214-20. [Medline].

  21. Martens M, De Rycke J. Facetectomy of the patella in patellofemoral osteoarthritis. Acta Orthop Belg. 1990;56(3-4):563-7. [Medline].

  22. Scott SH, Winter DA. Internal forces of chronic running injury sites. Med Sci Sports Exerc. Jun 1990;22(3):357-69. [Medline].

  23. Thomee R, Augustsson J, Karlsson J. Patellofemoral pain syndrome: a review of current issues. Sports Med. Oct 1999;28(4):245-62. [Medline].

  24. Wagenhauser FJ. [Clinical aspects of arthroses]. Verh Dtsch Ges Inn Med. 1989;95:449-62. [Medline].

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Keywords

patellofemoral syndrome, knee pain, patella, patellofemoral, knee cartilage, patellofemoral pain syndrome, pain behind knee, patellofemoral joint, kneecap pain, patella femoral, patella pain, patella femoral syndrome, PFPS, anterior knee pain, chondromalacia patella

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Contributor Information and Disclosures

Author

Patrick J Potter, BSc, MD, FRCP(C), Associate Professor, Physical Medicine and Rehabilitation, The University of Western Ontario; Consulting Staff, Department of Physical Medicine and Rehabilitation, St Joseph's Health Care Centre
Patrick J Potter, BSc, MD, FRCP(C) is a member of the following medical societies: American Paraplegia Society, Canadian Association of Physical Medicine and Rehabilitation, Canadian Medical Association, College of Physicians and Surgeons of Ontario, Ontario Medical Association, and Royal College of Physicians and Surgeons of Canada
Disclosure: Nothing to disclose.

Coauthor(s)

Keith AJ Sequeira, MD, Associate Director of Spinal Cord Medicine, Assistant Professor, Department of Physical Medicine and Rehabilitation, Parkwood Hospital, University of Western Ontario
Disclosure: Nothing to disclose.

Medical Editor

Robert E Windsor, MD, FAAPMR, FAAEM, FAAPM, President and Director, Georgia Pain Physicians, PC; Clinical Associate Professor, Department of Physical Medicine and Rehabilitation, Emory University School of Medicine
Robert E Windsor, MD, FAAPMR, FAAEM, FAAPM is a member of the following medical societies: American Academy of Pain Medicine, American Academy of Physical Medicine and Rehabilitation, American College of Sports Medicine, American Medical Association, International Association for the Study of Pain, Physiatric Association of Spine, Sports and Occupational Rehabilitation, and Texas Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Patrick M Foye, MD, FAAPMR, FAAEM, Associate Professor of Physical Medicine and Rehabilitation, Co-Director of Musculoskeletal Fellowship, Co-Director of Back Pain Clinic, Director of Coccyx Pain Service (Tailbone Pain Service: www.TailboneDoctor.com), University of Medicine and Dentistry of New Jersey, New Jersey Medical School
Patrick M Foye, MD, FAAPMR, FAAEM is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic Medicine, Association of Academic Physiatrists, and International Spine Intervention Society
Disclosure: Nothing to disclose.

CME Editor

Kelly L Allen, MD, Regional Medical Director, IMX-Medical Management Services
Disclosure: Nothing to disclose.

Chief Editor

Consuelo T Lorenzo, MD, Consulting Staff, Department of Physical Medicine and Rehabilitation, Alegent Health Care, Immanuel Rehabilitation Center
Consuelo T Lorenzo, MD is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation
Disclosure: Nothing to disclose.

 
 
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