Quadriceps Injury

Anatomy of a quadriceps injury

The quadriceps or “quads” are a group of four muscles that act together to straighten the knee. One of these muscles, the rectus femoris, also acts to bend the hip. The muscles involved in quadriceps strains are rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius. The focus of this page will be on the rectus femoris, which is the most commonly strained muscle of the quadriceps femoris group.¹

The quadriceps have a common attachment point at the top portion of the patella (knee cap). However, each of them starts in a different portion of the hip or thigh. The rectus femoris muscle attaches to the pelvis, which is why it also functions to bend the hip. Whereas the vastus lateralis attaches to the outer portion of the femur, and the vastus medialis attaches to the inner portion of the femur. The vastus intermedius sits deep to the rectus femoris and attaches to the front and outside portions of the femur.²

Quad strains are relatively uncommon in football players, with an injury rate of 4.5%. The injury site is usually located in the mid-portion of the top aspect of the rectus femoris, but it can also occur at the bottom portion of the muscle.³  Like all soft tissue injuries, there are different grades of injury; this is listed below.⁴

• Grade I (Mild strain):
• Microscopic damage to muscle fibers, often involving the rectus femoris
• Mild tightness or soreness, usually with no loss of strength
• Minimal to no swelling or bruising
• Athletes can often continue activity with discomfort
• Return to play: typically 1–2 weeks

• Grade II (Moderate strain or partial tear):
• Partial tearing of muscle fibers, commonly felt as a “pull” or sudden sharp pain
• Localized swelling and bruising may develop within 24–48 hours
• Pain with resisted knee extension and limited tolerance for sprinting or jumping
• A palpable defect may be present
• Return to play: usually 2–6 weeks, depending on severity and location

• Grade III (Severe strain or complete rupture):
• Full-thickness tear of the muscle or tendon
• Significant swelling, bruising, and a visible/palpable defect
• Severe weakness and loss of function, often unable to walk without aid
• Often requires imaging (MRI or ultrasound) to confirm the extent
• Surgical repair may be necessary, especially with a tendon rupture
• Return to play: 8+ weeks, often 3–4 months if surgery is involved

Cause of a quadriceps Injury

As with most muscular injuries, the typical cause of a quadriceps injury occurs due to excessive eccentric loading, which means the muscle is generating a high amount of force while it is being stretched. Quadriceps injuries are caused by eccentric hip flexion and knee extension when the hip is forced into extension (thigh moving behind the body) and the knee is forced into flexion (bent position), which is why the rectus femoris is most commonly involved.¹ The majority (63.2%) of quad strains are non-contact injuries. Many of these injuries happen during practice, but the injury rate is higher in games. It is also of note that they are much more common in the pre-season.

The recurrence rate for quad strains is 10-15%, which is relatively high, but most players were able to return to sport within 1-6 days.¹ This bodes well for fantasy purposes because most players will not miss any playing time.

Risk factors for quadriceps injury and recurrence are related to positional needs. Positions that require kicking, jumping, and sudden changes of direction are all at increased risk. The greatest risk factor for recurrence is a recent history of the same injury. Muscle fatigue also increases injury risk.³ Further modifiable risk factors consist of strength asymmetries and flexibility asymmetries. Interestingly, shorter and heavier athletes are also at increased risk.⁵

Quadriceps injury rehab process

The timeline for return to sport from a quadriceps injury depends heavily on the grade of the muscle strain. As stated previously, most players were able to return to sport within one week of the initial injury, and most athletes with grade 1 and 2 strains respond well to conservative treatment.1 Grade 3 strains or full-thickness ruptures will require surgical intervention and an extensive rehabilitation process that generally takes 3-5 months to return to play.⁶

The initial phase of rehabilitation focuses on protecting the muscle, reducing pain, and reducing swelling. However, initiating rehab as quickly as possible post-injury is crucial to prevent muscle weakness and atrophy.6 In general, this will be accomplished through rest, ice, compression, elevation, NSAIDs, and crutches for grade 3 strains.^3,6 Protection is also vital to prevent myositis ossificans, which is abnormal bone growth within the muscle that can occur from improper healing.⁴

Once tolerable, the active phase of rehabilitation begins. This stage initially focuses on pain-free active range of motion and pain-free stretching, which will help the damaged tissue heal properly.³ Progressive and controlled muscle loading will also be initiated with isometric contractions (muscle activates but the joint does not move) and will progress to concentric (muscle activates and joint moves) and eccentric loading as the muscle heals.⁶ Maintenance of aerobic fitness is also encouraged in this stage to maintain fitness and reduce muscle fatiguability, which in itself is a risk factor for injury. Similarly to stretching, all strengthening exercises should be pain-free. Progression of strengthening should be done cautiously and based on symptoms post-treatment.⁴ Jogging within tolerance will also occur in this phase and is often initiated with an anti-gravity treadmill.

The return to sport phase should be progressed once range of motion is symmetrical and pain-free. Strength testing should also be pain-free and symmetrical, which is often confirmed by isokinetic testing via a special Biodex machine.4 Sprinting, jumping, and cutting drills will be one of the final components to rehab and are vital to injury prevention. Once athletes pass all these checkpoints, they will begin position-specific training and contact drills. The return to sport phase is also where other preventative treatments can be utilized effectively. This will often include hip flexor strength training, core strength training, and proprioception (balance) exercises.

Rehab Phase	Treatments	Criteria to Enter Phase
Early Phase	Rest, ice, compression, elevation, NSAIDs. Crutches if needed. Soft tissue work, dry needling, electrical stimulation (pain control). Ankle and hip mobility exercises. Glute and core strength. Hip flexion and knee extension isometrics if tolerable.	N/A
Intermediate Phase	Soft tissue work, dry needling. Hip flexor and quad stretching. Ankle and hip mobility. Glute and core strengthening. Balance exercises. Jogging progression (anti-gravity treadmill) if tolerable.	Little to no pain with walking or isometrics.
Sports-Specific	Full weight lifting. Progress to 100% speed running. Agility, plyometrics. Position-specific drills.	Symmetrical and pain-free hip/knee mobility and strength. Adequate core stability. Adequate ankle mobility. Adequate single-leg balance. No pain with jogging.

References

1. Eckard TG, Kerr ZY, Padua DA, Djoko A, Dompier TP. Epidemiology of Quadriceps Strains in National Collegiate Athletic Association Athletes, 2009-2010 Through 2014-2015. J Athl Train. 2017;52(5):474-481.
2. Donnelly JM, Fernandez-de-las-Peñas C, Finnegan M, Freeman JL. In: Travell, Simons & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual. 3rd ed. United States: Wolters Kluwer Health; 2019
3. Lamplot JD, Matava MJ. Thigh Injuries in American Football. Am J Orthop (Belle Mead NJ). 2016;45(6).E308-E318.
4. Kary JM. Diagnosis and management of quadriceps strains and contusions. Curr Rev Musculoskelet Med. 2010;3(1-4):26-31. Published 2010 Jul 30.
5. Fousekis K, Tsepis E, Poulmedis P, Athanasopoulos S, Vagenas G. Intrinsic risk factors of non-contact quadriceps and hamstring strains in soccer: a prospective study of 100 professional players. Br J Sports Med. 2011;45(9):709-714.
6. Lempainen, L., Mechó, S., Valle, X. et al. Management of anterior thigh injuries in soccer players: practical guide. BMC Sports Sci Med Rehabil 14, 41 (2022).