Hip Flexor Strain

Players who have had a hip flexor strain

Quarterbacks

Quarterbacks	Games Missed	PPG Prior to Injury	PPG 1st Game After Injury	PPG Games 2-3 After Injury	PPG Games 4-6 After Injury
Ben Roethlisberger (2021 week 4)	0	15.2	16 (+0.8)	12.8 (-2.4)	16.5 (+1.3)
Average	0		+0.8	-2.4	+1.3
Number of Players Who Have Met Their Baseline at Current or Previous Time Points			1/1 (100%)	1/1 (100%)	1/1 (100%)

Running Backs

Running Backs	Games Missed	PPG Prior to Injury	PPG 1st Game After Injury	PPG Games 2-3 After Injury	PPG Games 4-6 After Injury
Gio Bernard (2021 week 14)	4	2.8	N/A	N/A	N/A
Rex Burkhead (2021 week 14)	0	4.9	5.2 (+0.3)	19.4 (+14.5)	8.1 (+3.2)*
Melvin Gordon (2021 week 12)	1	11.2	23.1 (+11.9)	3.6 (-7.6)	12.4 (+1.2)
Devonte Booker (2021 week 9)	0	10	2.5 (-7.5)	5.3 (-4.7)	8.7 (-1.3)
Rex Burkhead (2021 week 5)	1	6.5	0 (-6.5)	6.2 (-0.3)	3.9 (-2.6)
Jamaal Williams (2021 week 5)	0	8.7	1.4 (-7.3)	3.4 (-5.3)	9 (+0.3)
Philip Lindsay (2020 week 15)μ	2	5.1	N/A	N/A	N/A
Kenyan Drake (2020 week 14)	0	15.3	5 (-10.3)	9.3 (-6)	N/A
Philip Lindsay (2020 week 14)	0	5.1	N/Aμ	N/Aμ	N/Aμ
Average	0.9		-3.2	-1.6	+0.2
Number of Players Who Have Met Their Baseline at Current or Previous Time Points			2/6 (33%)	2/6 (33%)	3/6 (50%)

Wide Receivers

Wide Receivers	Games Missed	PPG Prior to Injury	PPG 1st Game After Injury	PPG Games 2-3 After Injury	PPG Games 4-6 After Injury
Ja’Marr Chase (2022 week 6)	0	14.9	29 (+14.1)	N/Aψ	N/Aψ
CeeDee Lamb (2022 week 6)	0	11.8	8.6 (-3.2)	25.4 (+13.6)	14 (+2.2)
Nico Collins (2021 week 11)	0	4.4	3.8 (-0.6)	4.7 (+0.3)	5.9 (+1.5)
Corey Davis (2021 week 7)	2	10.8	9.8 (-1)	3.8 (-7)	N/A
Tyler Lockett (2021 week 3)	0	16.3	4.4 (-11.9)	6.4 (-9.9)	9 (-7.3)
Michael Gallop (2020 week 15)	0	7.9	27.1 (+19.2)	6.9 (-1)*	N/A
Danny Amendola (2020 week 10)	2	6.5	7.7 (+1.2)	6.6 (+0.1)	3.7 (-2.8)
Kenny Golladay (2020 week 8)	8	14	N/A	N/A	N/A
Jarvis Landry (2020 week 1)	0	13.8	6.1 (-7.7)	9.2 (-4.6)	8.3 (-5.5)
Corey Davis (2019 week 9)	1	8.6	3.9 (-4.7)	3.6 (-5)	6.4 (-2.2)
Julio Jones (2017 week 4)	0	12.7	10.2 (-2.5)	14.7 (+2)	11 (-1.7)
Average	1.4		+0.3	-1.3	-2.3
Number of Players Who Have Met Their Baseline at Current or Previous Time Points			3/9 (33%)	5/9 (56%)	5/9 (56%)

Tight Ends

Tight Ends	Games Missed	PPG Prior to Injury	PPG 1st Game After Injury	PPG Games 2-3 After Injury	PPG Games 4-6 After Injury
Blake Jarwin (2021 week 8)	8	4.3	N/A	N/A	N/A
Robert Tonyan (2019 week 5)	5	1.4	1.8 (+0.4)	3.4 (+2)	0.9 (-0.5)
Jack Doyle (2018 week 2)	5	7.4	16 (+8.6)	5.7 (-1.7)	9.6 (+2.2)*
Average	6		+4.5	+0.2	+0.9
Number of Players Who Have Met Their Baseline at Current or Previous Time Points			2/2 (100%)	2/2 (100%)	2/2 (100%)
Average	6		+4.5	+0.2	+0.9
Number of Players Who Have Met Their Baseline at Current or Previous Time Points			2/2 (100%)	2/2 (100%)	2/2 (100%)

Anatomy of a hip flexor strain

The term “hip flexor” is used frequently in sports and exercise and is a combination of muscles that act to flex the hip (bring the thigh upward towards the chest). The primary muscles that perform this motion are the Psoas Major and the Iliacus. However, other muscles are involved, including the Rectus Femoris, Tensor Fascia Latae (TFL), and to a lesser degree, some of the adductor muscles.^1,2 This page focuses on the Psoas and the Iliacus, who form together to become the Iliopsoas muscle.

The Psoas portion attaches at the T12-L5 vertebra, and the Iliacus muscle attaches at the inside portion of the Ilium (big hip bone), and they blend to attach to the inner portion of the femur bone. The Psoas is uniquely the only muscle that directly attaches from the spine to the leg.² The anatomy of the Iliopsoas muscle allows it to function as a powerful hip flexor muscle making it highly important in running, as it helps drive the leg forward but also must control the trail leg.^1,2

Muscle strains are the most common type of hip injury, with hip flexor injuries being second most common after groin injuries and accounting for roughly 29% of all hip injuries in football players.³ A hip flexor injury can occur either in the muscle belly or in the tendinous attachment to the femur bone.⁴

Cause of a hip flexor strain

Approximately 70% of hip flexor injuries occur from non-contact mechanisms, often due to overuse, overstretching of the muscle, or when the player is attempting to pull the leg forward but is tackled in a way that their leg is heavily resisted by the opponent, causing excessive contraction of the hip flexor muscles.^3,5 Some athletes experience hip impingement syndrome, where the femur bone pinches the hip flexor muscles against the acetabulum (hip socket bone) when running and squatting.¹ This condition can contribute to irritation of the hip flexor muscles and tendons, contributing to pain with overuse.

There is some data in collegiate football players on positions that occur hip injuries most frequently (not specific to hip flexor strains). One study shows that of all hip injuries, 5.8% occur in quarterbacks, 10.3% occur in running backs, 15.9% occur in wide receivers, and the remaining in other non-fantasy relevant positions (tight end was not listed).⁵

The recurrence rate of injury for hip flexor strains is somewhat high, with studies averaging around an 8% injury recurrence within two months of returning to sport.^3,5 This high rate signifies the importance of a proper rehabilitation program to reduce the likelihood of re-injury.

Some risk factors for a hip flexor strain have been suggested but are not quite as clear as other injuries. These include previous history of hip or groin injuries, reduced strength, limited hip flexibility, poor core and trunk strength and stability, and improper training.⁶ Some of these factors are modifiable if the athlete seeks proper physical therapy and engages in a proper training program. 

hip flexor strain rehab process

The timeline for return to sport following a hip flexor strain is typically not very long, with around 70% of players missing less than six days due to injury and 19% missing 7-13 days, with the remaining missing >14 days.^3,5 In football, this correlates to most players not missing any games, and almost all athletes respond well to conservative treatment.

The initial phase of rehab will focus on pain control and reducing swelling. This is performed through rest, ice, compression, elevation, electrical stimulation, manual release of the hip flexor muscles, and possibly crutches for a few days.² In this early phase, if tolerable, the athlete may continue to cycle to maintain cardiovascular fitness. During this phase, it is vital to identify potential factors that may have contributed to the injury.² This may include ankle stiffness, hip weakness, and poor core and trunk stability. Many of these factors can begin to be addressed during this phase. 

As mentioned above, one mechanical factor that can contribute to hip flexor strains is the presence of a hip impingement, where the femur bone pinches the muscles and tendons against the hip socket bone as the leg comes forward.¹ In some instances, this is secondary to excessive bone growth and may not be able to be managed conservatively. However, in other cases, this may be secondary to poor muscle control, particularly with overuse of the hip flexor muscles and poor activation of the core muscles. If the latter is present conservative care should focus on correcting the muscle control.

As pain begins to subside, rehab should continue to work on the above-listed treatments as well as begin to stretch the hip flexor muscle in tolerable ranges, and initiate running, ideally starting on an anti-gravity treadmill. It is crucial to progress core stability exercises from the floor or table to more functional positions. A nice transition is to go from exercises on the table to exercises while sitting on an exercise ball to standing. Athletes need their core to function properly while running, catching, blocking, tackling, etc.; therefore, it is important to train the core in similar positions.

When transitioning to the return to sport phase of rehab it is important that the underlying factors that may have predisposed the athlete to injury in the first place are addressed. As mentioned above these often include hip weakness, hip flexibility limitations, poor trunk and core stability, limitations in ankle mobility, and also sound single leg stability on the injured side compared to the uninjured side. When these issues are resolved and the athlete has no or very minimal pain with running they should begin full strength training, agility training, plyometrics, speed work, and position specific training.

Rehab Phases	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. Glute and core strength. Hip flexor isometrics if tolerable.	N/A first phase
Intermediate Phase	Soft tissue work, dry needling. Hip flexor stretching. Ankle and hip mobility. Glute and core strength progressing to functional positions (sitting on exercise ball > standing). Balance exercises. Gentle jogging (anti-gravity treadmill) if tolerable.	Little to no pain with walking or single leg balance.
Sports Specific	Full weight lifting. Progress to 100% speed running. Agility, plyometrics. Position specific drills.	Adequate hip flexibility and strength. Adequate core stability. Adequate ankle mobility. Adequate single leg balance. No pain with jogging.

Generally, hip flexor injuries respond very well to conservative care, and the need for surgery is rare.^1,3,5 If surgery were to be indicated, it would likely be due to a hip impingement and may be held until the offseason. 

References

1. Dydyk A, Sapra A. Psoas Syndrome. In: StatPearls. Treasure Island (FL): StatPearls Publishing; November 2, 2021.
2. Tyler T, Fukunaga T, Gellert J. Rehabilitation of Soft Tissue Injuries of the Hip and Pelvis. Int J Sports Phys Ther. 2014;9(6):785-797.
3. Makovicka J, Chiabra A, Patel K, Tummala S, Hartigan D. A decade of Hip Injuries in National Collegiate Athletic Association Football Players: An Epidemiologic Study Using National Collegiate Athletic Association Surveillance Data. J. Athl. Train. 2019;54(5):483-488.
4. Tsukada S, Niga S, Nihei T, Imamura S, Saito m, Hatanka J. Iliopsoas Disorder in Athletes with Groin Pain. JBJS Open Access. 2018.
5. Eckard T, Pauda D, Dompier T, Dalton S, Thorborg K, Kerr Z. Epidemiology of Hip Flexor and Hip Adductor Strains in National Collegiate Athletic Association Athletes, 2009/2010-2014/2015. Am J Sports Med. 2017;45(12):2713-2723.
6. Weir A, Brukner P, Delahunt E, et al. Doha agreement meeting on terminology and definitions in groin pain in athletes. Br J Sports Med. 2015;49:768-774.