Conditions: Patellofemoral Pain Syndrome
Keywords: Botulinum toxin type A Patellofemoral pain syndrome Knee Injuries Exercise Therapy
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 5
Healthy volunteers: no

Brief summary:
The purpose of this study is to determine whether the use of botulinum toxin A injected into the lateral thigh muscle improves knee function and reduces knee pain secondary to patellofemoral syndrome. The study hypothesis is that botulinum toxin + specific exercises will be superior to specific exercises alone in improving knee function and reducing knee pain in individuals with patellofemoral syndrome.

Detailed description:
Patellofemoral pain syndrome is a leading cause of knee pain in persons under 45 and is particularly common in women. The prevailing theory for the etiology of patellofemoral pain is an imbalance in force or timing of the pull of the knee extensor muscles on the patella resulting in improper tracking of the patella in the femoral grove. Specifically, the vastus medialis is thought to be ineffective in overcoming the lateral pull of the vastus lateralis. When exercises designed to focus on improving strength and timing of activation of the vastus medialis fail, surgical release of part of the attachment of the vastus lateralis to the patella is considered.

Botulinum toxin temporarily blocks acetylcholine release from motor neurons and is used clinically to produce muscle relaxation.

Subjects with patellofemoral syndrome will be recruited into the study. Half of the subjects will be given a placebo injection while the other half will be given an injection of Botox (Botulinum Toxin A, Allergen) into the vastus lateralis muscle. Group assignment will be randomized and a double blind protocol used. Prior to injection, the subject will record their level of knee pain, fill out several knee function questionnaires, and have the strength and endurance of their knee extensor muscles tested. All subjects will be given an exercise program designed to target strengthening of the medial thigh muscles as well as stretching of lateral structures.

At 4, 6 and 12 weeks knee pain and knee function will again be assessed.

Arms:
arm 1: Injection of Botulinum toxin A into vastus lateralis of study limb plus exercise program arm 2: Placebo injection + exercise

Interventions: intervention 1: Botulinum toxin A + exercise intervention 2: Placebo
Intervention descriptions: intervention 1: Injection of 100 units Botox (Botulinum toxin type A) into the Vastus Lateralis of the study leg + 12 weeks of exercise for patellofemoral pain intervention 2: Injection of 2 cc placebo containing 0.1cc sodium bicarbonate 8.4% (1meq/cc), 0.9cc normal saline and 1 cc of lidocaine into the vastus lateralis of the study leg followed by 12 weeks of exercise for patellofemoral pain syndrome

Protocol document: