Hamstring injuries Review

Introduction

Hamstring injuries are among the most prevalent musculoskeletal injuries in sports, accounting for a substantial proportion of time-loss injuries in athletes across multiple disciplines. These injuries occur with particular frequency in sports involving repetitive kicking, high-speed sprinting, rapid acceleration-deceleration, and eccentric muscle loading, including American football, soccer, rugby, athletics, and Australian rules football [1,2,3]. The clinical and economic burden of hamstring injuries is significant, with recurrence rates ranging from 14% to 63%, making prevention and optimal management critical priorities in sports medicine [1,4].

Despite decades of research, hamstring injuries remain challenging to manage due to their complex pathophysiology, variable presentation, and high recurrence rates. The injury spectrum ranges from minor muscle strains that resolve with conservative management to complete proximal avulsions requiring surgical intervention [5,6]. Understanding the anatomical basis, injury mechanisms, diagnostic approaches, and evidence-based treatment strategies is essential for clinicians managing athletes with hamstring injuries [7,8].

This comprehensive review synthesizes current evidence on hamstring injury anatomy, mechanisms, MRI-based grading systems, return-to-play protocols, non-surgical treatments, and surgical options. The goal is to provide sports medicine practitioners, orthopedic surgeons, physical therapists, and athletic trainers with a practical, evidence-based framework for managing hamstring injuries across the spectrum of severity and optimizing athlete outcomes [9,10].

Anatomy:

Muscle Composition and Structure

The hamstring muscle group comprises three distinct muscles located in the posterior compartment of the thigh: the biceps femoris, semitendinosus, and semimembranosus [2,18]. These muscles function collectively to extend the hip and flex the knee, playing crucial roles in running, jumping, and deceleration activities [11]. The biceps femoris consists of two heads—a long head and a short head—with the long head being part of the true hamstring complex, while the short head has a separate origin and is not considered a true hamstring muscle [2,18].

The hamstring muscles are biarticular, crossing both the hip and knee joints, which predisposes them to injury during activities requiring simultaneous hip flexion and knee extension [7,11]. The architectural characteristics of these muscles, including their long muscle fibers and relatively small physiological cross-sectional area, contribute to their vulnerability to strain injuries [18]. The biceps femoris long head is the most commonly injured hamstring muscle, accounting for the majority of acute hamstring strains in athletes [2, 7,18].

Origins and Insertions

The three hamstring muscles share a common proximal origin at the ischial tuberosity, with the exception of the biceps femoris short head [2,18]. Specifically, the long head of the biceps femoris, semitendinosus, and semimembranosus all originate from the ischial tuberosity via a conjoint tendon, though the semimembranosus has a separate, more lateral attachment [18]. This common origin site is clinically significant as it represents a location vulnerable to avulsion injuries, particularly in activities involving extreme hip flexion with knee extension, such as waterskiing, gymnastics, and dancing [2,17].

 

Figure 1 – Posterior Thigh – Hamstring Anatomy

Distally, the hamstring muscles have distinct insertions. The biceps femoris inserts on the fibular head and lateral tibial condyle (see figure 2), while the semitendinosus and semimembranosus insert medially on the proximal tibia (see figure 3) with the SM forming part of the pes anserinus complex [2,18]. The semitendinosus has a long, cord-like tendon that inserts on the medial aspect of the proximal tibia, whereas the semimembranosus has a broader, flatter insertion with multiple attachments including the posteromedial tibia, posterior joint capsule, and oblique popliteal ligament [18]. Understanding these anatomical relationships is essential for accurate diagnosis and surgical planning in cases of distal hamstring injuries [2].

Innervation

The hamstring muscles receive their innervation from the sciatic nerve (L4-L3) and its branches [2,18,32]. Specifically, the long head of the biceps femoris, semitendinosus, and semimembranosus are innervated by the tibial division of the sciatic nerve, while the short head of the biceps femoris is innervated by the common peroneal (fibular) division [18]. This dual innervation pattern of the biceps femoris reflects its embryological origin from different muscle masses and has clinical implications for nerve injury patterns [2].

The nerve supply to the hamstring muscles enters proximally, typically in the upper third of the thigh, and branches extensively within the muscle bellies [18]. Injury to the sciatic nerve or its branches can result in hamstring weakness and must be differentiated from primary muscle injury during clinical evaluation [2]. Additionally, neural tension and adverse neural dynamics have been implicated as potential contributing factors to hamstring injury risk and recurrence, though the evidence remains evolving [11].

Vascular Supply

The hamstring muscles receive their arterial blood supply primarily from the profunda femoris artery and its perforating branches, supplemented by contributions from the inferior gluteal artery proximally and the popliteal artery distally [2,18]. The first and second perforating arteries of the profunda femoris provide the dominant blood supply to the muscle bellies, entering the muscles from their deep surface [18]. The inferior gluteal artery supplies the proximal portions of the muscles near their origin at the ischial tuberosity [2].

Venous drainage follows the arterial supply, with blood returning via the profunda femoris vein and ultimately to the femoral vein [18]. The vascular anatomy is clinically relevant for several reasons: adequate blood supply is essential for healing after injury, hematoma formation is common in acute hamstring strains, and surgical approaches must preserve the neurovascular structures to minimize complications [2,18]. Understanding the vascular supply also helps explain the typical imaging findings on MRI, where intramuscular edema and hemorrhage are hallmarks of acute hamstring injury [7,18].

Injury Mechanisms and Locations

Hamstring injuries typically occur through two primary mechanisms: high-speed running injuries and stretch-type injuries [3, 7, 11]. High-speed running injuries, also termed “sprinting-type” injuries, are the most common mechanism in sports and occur during the late swing phase of running when the hamstring muscles undergo eccentric contraction to decelerate the extending knee and prepare for foot strike [3, 7, 11]. During this phase, the hamstring muscles are maximally lengthened while generating force, creating conditions of high mechanical stress that predispose to injury [11,15]. These injuries most commonly affect the biceps femoris long head at the myotendinous junction in the mid-to-distal thigh [3,7,18].

Stretch-type injuries occur when the hamstring muscles are subjected to extreme lengthening, typically during activities involving hip flexion with knee extension, such as high kicks, splits, sliding tackles, or waterskiing [3], [7], [11]. These injuries tend to occur more proximally, often involving the proximal myotendinous junction or the proximal free tendon near the ischial tuberosity [3], [17], [18]. Stretch-type injuries are more likely to result in complete avulsions of the proximal hamstring origin, particularly in older athletes or those with chronic tendinopathy [2], [17]. The mechanism of injury has important prognostic implications, with stretch-type injuries generally requiring longer recovery times than sprinting-type injuries [3], [7].

Figure 2 – Biceps Femoris Insertion

Figure 3 – Semitendinosus and Semimembranosus Insertion

Figure 4 – Pes Anserine (Tendons Cranial – caudal – Sartorisu, Gracillus, Semitendinosus) – Cadaver 

 

Common Injury Locations

Hamstring injuries can occur at various locations (see figure 5) along the muscle-tendon unit, with the specific location influencing prognosis and management [3, 7,18]. The most common site of injury is the myotendinous junction (MTJ), where muscle fibers transition to tendon, representing a region of high mechanical stress and structural vulnerability [3, 7,11]. Within the MTJ, the proximal MTJ (near the ischial tuberosity) and the distal MTJ (in the mid-to-distal thigh) are both susceptible to injury, though the distal MTJ of the biceps femoris long head is the single most common injury site in sprinting athletes [3,7,18].

Figure 5 – Hamstring Injury by location, tissue type and muscle [33]

Intramuscular injuries occur within the muscle belly itself and can be further classified as myofascial (involving the central tendon or aponeurosis) or purely intramuscular [3,18]. Myofascial injuries, which involve the intramuscular tendon or aponeurosis, are associated with longer recovery times compared to purely intramuscular injuries [3,7,18]. Proximal injuries include complete or partial avulsions of the conjoint tendon from the ischial tuberosity, which are relatively uncommon but clinically significant due to their potential need for surgical repair [2,17]. Distal hamstring injuries, involving the insertion sites at the knee, are rare but can occur in contact sports or during forced knee extension against resistance [2,18].

The location of injury has important prognostic implications. Proximal injuries and those involving the proximal free tendon are associated with longer recovery times, with some studies reporting mean return-to-play times exceeding 50 days [3,7]. Injuries involving the intramuscular tendon or aponeurosis similarly predict prolonged recovery [3,18]. In contrast, peripheral muscle injuries without tendon involvement typically have shorter recovery periods [3,7]. Understanding injury location through detailed MRI assessment is therefore critical for accurate prognosis and treatment planning [7,18].

Risk Factors

Multiple risk factors for hamstring injury have been identified through epidemiological and biomechanical research [11,15,22]. Previous hamstring injury is the single strongest and most consistently identified risk factor, with athletes who have sustained a prior hamstring injury being 2-6 times more likely to experience a recurrent injury [11,15, 22, 30]. This elevated recurrence risk persists for at least one year following the initial injury and may reflect incomplete rehabilitation, persistent strength deficits, altered neuromuscular control, or structural changes in the muscle-tendon unit [11,15, 22].

Age is another significant risk factor, with older athletes demonstrating higher injury rates and longer recovery times [11,15]. Hamstring strength deficits, particularly eccentric strength weakness and imbalances between hamstring and quadriceps strength (H:Q ratio), have been associated with increased injury risk [11,15, 22]. Reduced hamstring flexibility, though historically emphasized, has shown inconsistent associations with injury risk in recent research [11,15]. Other identified risk factors include inadequate warm-up, fatigue, poor lumbopelvic control, reduced hip flexor flexibility, and sport-specific factors such as high-speed running exposure [11,15,22].

Biomechanical factors contributing to injury risk include altered running mechanics, reduced hip extension range of motion, and impaired neuromuscular control during high-speed activities [11,15]. Fatigue has been shown to alter hamstring muscle activation patterns and increase injury susceptibility, particularly late in matches or training sessions [11,15]. Understanding these multifactorial risk factors is essential for developing comprehensive injury prevention programs and identifying athletes at elevated risk who may benefit from targeted interventions [11,15,22,25].

Imaging

Ultrasound and MRI are the imaging modalities used to assess  hamstring injuries.

MRI carries some increased accuracy and improved correlation with return to play prognostication than ultrasound alone.

Ultrasound and MRI are complementary imaging modalities for hamstring injury assessment, each with distinct advantages and limitations. Ultrasound offers real-time dynamic assessment, point-of-care availability, lower cost, and suitability for serial monitoring, making it an excellent first-line tool for muscle belly and musculotendinous junction injuries. High-resolution ultrasound demonstrates 80-90% concordance with MRI for these injury types and is as useful as MRI for depicting acute injuries [37, 38].

However, ultrasound has important limitations including operator dependence, limited field of view, reduced accuracy for proximal tendon injuries (60% concordance), and variable prognostic value. MRI provides superior soft tissue contrast, comprehensive visualization, and is the gold standard for proximal tendon injuries, subtle edema detection, and complex cases. MRI is essential for suspected proximal hamstring avulsions, where MRI-first approach results in shorter time to surgery and better functional outcomes [39].

The correlation between imaging findings and return to play time is modest for both modalities, with most studies explaining less than 20% of variance in RTP time. Specific prognostic factors include injury location (proximal tendon involvement predicts prolonged recovery), longitudinal extent, cross-sectional area, and connective tissue involvement. However, the wide overlap in recovery times across imaging grades limits the utility of imaging for individual prognostication [40,41].

Clinical recommendations based on current evidence include:

1. Use ultrasound for initial assessment of suspected muscle belly or MTJ injuries when expertise is available
2. Use MRI first-line for suspected proximal tendon injuries or avulsions
3. Integrate imaging findings with clinical assessment, functional testing, and athlete-specific factors for RTP decisions
4. Consider serial ultrasound for monitoring healing in high-grade injuries
5. Base RTP primarily on clinical criteria rather than imaging normalization

Future directions include development of advanced quantitative imaging techniques (shear wave elastography, diffusion tensor imaging), artificial intelligence applications, standardization of protocols, and identification of imaging biomarkers for reinjury prediction. The optimal approach to hamstring injury imaging requires individualized decision-making based on clinical context, injury characteristics, available resources, and operator expertise [42].

Ultimately, imaging should be viewed as a valuable adjunct to, rather than replacement for, thorough clinical assessment in the management of hamstring injuries. The integration of clinical evaluation, functional testing, and appropriately selected imaging provides the best foundation for accurate diagnosis, realistic prognostication, and safe return to play decisions in athletes with hamstring injuries.

 

Prognostic Value of MRI Grading

MRI-based grading systems (see https://sportmedschool.com/mri-based-grading-systems-for-muscle-injuries/ for in depth comparison)  have demonstrated significant prognostic value for predicting recovery time and return-to-play in athletes with hamstring injuries [7,18,23, 24]. Multiple studies have shown strong correlations between injury grade, anatomical location, and time to return to sport [7,18,23]. Higher-grade injuries (Grade 2-3 in most systems) are consistently associated with longer recovery times, often exceeding 4-6 weeks, compared to Grade 1 injuries which typically resolve within 2-3 weeks [7,18].

Specific MRI features that predict prolonged recovery include: involvement of the proximal free tendon, myofascial injuries affecting the intramuscular tendon or aponeurosis, greater longitudinal extent of injury (>10 cm), larger cross-sectional area involvement (>50%), and complete tendon avulsions [7,18,23]. Conversely, peripheral muscle injuries without tendon involvement and injuries with smaller cross-sectional area (<10%) are associated with faster recovery [7,18]. The prognostic value of MRI grading has important clinical implications, allowing clinicians to provide athletes with realistic recovery timelines, plan rehabilitation protocols, and make informed decisions about the need for surgical intervention [7,18,23,24].

Return to Play Protocols

Criteria-Based Approaches

Criteria-based return-to-play (RTP) approaches emphasize objective functional and clinical milestones that athletes must achieve before returning to full sport participation [3, 8, 26,30]. These approaches recognize that recovery from hamstring injury is highly individual and that time-based protocols alone may not adequately assess readiness for sport [8, 26,30]. Common criteria used in evidence-based RTP protocols include: absence of pain during functional activities, restoration of hamstring strength to within 10% of the uninjured limb, achievement of normal or near-normal hamstring flexibility, successful completion of sport-specific functional tests, and clearance by medical staff [8,26,30].

Strength assessment is a cornerstone of criteria-based RTP, with particular emphasis on eccentric hamstring strength and the hamstring-to-quadriceps (H:Q) strength ratio [3, 8,11,26]. Isokinetic dynamometry is often used to objectively measure strength, with many protocols requiring <10% side-to-side difference before clearing athletes for return to sport [8, 26,30]. Functional performance tests commonly incorporated into RTP criteria include the asymptomatic completion of progressive running drills, high-speed sprinting, change-of-direction tasks, and sport-specific movements [8,26,30]. Some protocols also include hop tests, such as single-leg hop for distance and triple hop tests, to assess lower limb power and confidence [8,26].

Despite the widespread use of criteria-based approaches, a systematic review found that none of the commonly used RTP criteria have been formally validated for their ability to predict safe return to sport or reduce reinjury risk [30]. This lack of validation represents a significant gap in the evidence base and highlights the need for prospective research to identify which criteria best predict successful RTP [26], [30]. Nevertheless, criteria-based approaches remain the recommended standard of care, as they provide a more individualized and comprehensive assessment of recovery compared to time-based protocols alone [3,8,26,30].

Time-Based Approaches

Time-based return-to-play approaches use injury severity and MRI grading to estimate recovery timelines and guide RTP decisions [7,24,26]. These approaches are based on epidemiological data showing that injury grade and anatomical location correlate with average recovery times [7,24]. For example, Grade 1 hamstring injuries typically require 2-3 weeks for RTP, Grade 2 injuries require 4-6 weeks, and Grade 3 injuries or complete avulsions may require 3-6 months or longer [7,24]. Proximal free tendon injuries and myofascial injuries are associated with longer recovery times, often exceeding 6-8 weeks [7,18].

While time-based approaches provide useful prognostic information and help set realistic expectations, they have significant limitations [24,26,30]. Recovery times show substantial individual variation, even among athletes with similar injury grades [24,26]. Factors such as age, previous injury history, sport demands, and adherence to rehabilitation can significantly influence recovery trajectory [11,15,24]. Relying solely on time-based protocols may result in premature return to sport in some athletes (increasing reinjury risk) or unnecessarily delayed return in others (reducing athletic performance and increasing economic costs) [24,26].

Current best practice recommends integrating time-based estimates with criteria-based assessments to optimize RTP decision-making [3,8,24,26]. MRI grading provides valuable prognostic information that can guide rehabilitation planning and set initial recovery timelines, while objective functional criteria ensure that athletes have adequately recovered before returning to full sport participation [3, 8, 24,26]. This hybrid approach balances the prognostic value of imaging with the individualized assessment of functional recovery [8,24, 26].

Functional Testing and Assessment

Functional testing plays a critical role in assessing readiness for return to play following hamstring injury [3,8, 26]. A comprehensive functional assessment typically includes progressive stages of activity, starting with pain-free walking and jogging, advancing to high-speed running and sprinting, and culminating in sport-specific movements and full training participation [3,8,12]. The ability to perform these activities without pain, apprehension, or compensatory movement patterns is essential before clearing athletes for competitive play [8,26].

Specific functional tests commonly used in hamstring injury rehabilitation include: progressive running protocols with gradual increases in speed and distance, acceleration and deceleration drills, change-of-direction tasks, jumping and landing assessments, and sport-specific skills such as kicking or cutting [3,8,12,26]. The Askling H-test, which involves a rapid hip flexion movement with the knee extended, has been proposed as a clinical test to assess hamstring function and readiness for RTP, though its predictive validity requires further validation [3,8]. Some protocols incorporate GPS monitoring and high-speed running metrics to objectively quantify training loads and ensure athletes can tolerate sport-specific demands before returning to competition [8, 24].

Psychological readiness is an often-overlooked component of RTP assessment [26,30]. Fear of reinjury, reduced confidence, and anxiety about returning to sport can affect performance and potentially increase injury risk [26]. Some RTP protocols incorporate psychological screening tools or require athletes to demonstrate confidence and willingness to return to full participation [26,30]. A comprehensive functional assessment should therefore address physical, physiological, and psychological dimensions of recovery to optimize outcomes and minimize reinjury risk [8, 26, 30].

Current Evidence and Recommendations

Current evidence supports a criteria-based, progressive approach to return to play following hamstring injury, with RTP decisions guided by objective functional milestones rather than time alone [3, 8, 26, 30]. A systematic review of RTP practices found significant heterogeneity in definitions and criteria used across studies, highlighting the lack of standardization in the field [30]. Only half of included studies provided a clear definition of RTP, and none of the commonly used criteria had been validated for their ability to predict safe return or reduce reinjury risk [30].

Despite these limitations, expert consensus and clinical guidelines recommend that RTP decisions should be based on: (1) absence of pain during functional activities, (2) restoration of strength to within 10% of the uninjured side, (3) achievement of adequate flexibility, (4) successful completion of sport-specific functional tests, and (5) psychological readiness [3,8,26,30]. The rehabilitation process should follow a progressive, staged approach, with athletes advancing through phases of increasing intensity and complexity as they meet specific criteria at each stage [3,8,12].

Recent research has emphasized the importance of addressing modifiable risk factors during rehabilitation to reduce reinjury risk [11,15,25,26]. This includes eccentric strengthening, lumbopelvic control training, optimization of running mechanics, and gradual exposure to high-speed running [11,12,15]. The high recurrence rate of hamstring injuries (14-63%) underscores the need for comprehensive rehabilitation that not only restores function but also addresses underlying risk factors [1,11,15,22]. Future research should focus on validating specific RTP criteria, identifying predictors of successful RTP, and developing standardized protocols that can be applied across different sports and settings [26,30].

Management

Acute Phase 

Acute phase management of hamstring injuries focuses on controlling pain and inflammation, protecting the injured tissue, and initiating early mobilization to promote healing [1,3,12,15]. The traditional RICE protocol (Rest, Ice, Compression, Elevation) has been widely used, though recent evidence suggests that complete rest may delay recovery and that early controlled mobilization is beneficial [3,12,15]. Current recommendations emphasize a modified approach: relative rest (avoiding activities that provoke pain while maintaining pain-free movement), ice application for pain relief, compression to minimize swelling, and elevation to reduce edema [3, 12,15].

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used for pain management in the acute phase, though their impact on healing remains controversial [3,15]. While NSAIDs effectively reduce pain and inflammation, some evidence suggests they may impair muscle regeneration and delay healing when used extensively [15]. Current recommendations suggest judicious use of NSAIDs for short-term pain relief (2-3 days) rather than prolonged courses [3,15]. Analgesics such as acetaminophen may be preferred for pain management beyond the acute phase [3].

Early mobilization and gentle stretching within pain-free ranges are now recommended to promote healing and prevent excessive scar tissue formation [3,12,15]. Progressive loading of the injured muscle should begin as soon as tolerated, typically within the first few days after injury [3,12]. This early functional approach has been shown to reduce recovery time and improve outcomes compared to prolonged immobilization [3,12,15]. The acute phase typically lasts 3-7 days, after which rehabilitation progresses to more intensive strengthening and functional training [3, 12].

Eccentric Training

Eccentric strengthening has emerged as the cornerstone of hamstring injury rehabilitation, with strong evidence supporting its effectiveness in promoting recovery and reducing reinjury risk [3,11,12,15,25]. Eccentric exercises involve lengthening contractions of the hamstring muscles, which specifically target the muscle-tendon unit in a manner that mimics the demands of high-speed running [11,12,15]. The Nordic hamstring exercise, which involves a controlled forward lowering movement from a kneeling position, is the most widely studied and recommended eccentric exercise for hamstring rehabilitation and injury prevention [11,12,15,25].

Multiple studies have demonstrated that eccentric training programs accelerate recovery, improve strength, and reduce the risk of recurrent hamstring injury [11,12,15, 25]. A systematic review found that eccentric strengthening was superior to conventional rehabilitation in reducing reinjury rates and improving functional outcomes [11,15]. The mechanisms underlying the benefits of eccentric training include: increased muscle fascicle length, improved eccentric strength, enhanced neuromuscular control, and structural adaptations in the muscle-tendon unit that increase resilience to high-speed running demands [11, 12, 15].

Eccentric training protocols typically begin with low-intensity exercises and progress gradually in volume and intensity as the athlete’s tolerance improves [3,12,15]. Early-phase eccentric exercises may include prone hamstring curls with resistance bands or gentle Nordic hamstring variations with support [12]. As rehabilitation progresses, exercises advance to full Nordic hamstrings, single-leg Romanian deadlifts, and eccentric hamstring slides [12,15]. The optimal dosage and progression of eccentric training remain areas of ongoing research, but current evidence supports 2-3 sessions per week with progressive overload [11,12,15,25].

Progressive Agility and Trunk Stabilization (PATS)

The Progressive Agility and Trunk Stabilization (PATS) program represents an alternative rehabilitation approach that emphasizes early functional training, agility, and lumbopelvic control [3,12]. Developed by Sherry and colleagues, the PATS protocol incorporates progressive agility drills, trunk stabilization exercises, and sport-specific movements earlier in the rehabilitation process compared to traditional programs [12]. The program is based on the premise that hamstring injuries often occur in the context of poor lumbopelvic control and that addressing these deficits is essential for optimal recovery [12].

A randomized controlled trial comparing the PATS program to a traditional stretching and strengthening protocol found that athletes in the PATS group returned to sport faster and had significantly lower reinjury rates at one-year follow-up [12]. The PATS program includes exercises such as single-leg balance activities, trunk stabilization drills, progressive running and cutting exercises, and sport-specific agility tasks [12]. The program emphasizes quality of movement, neuromuscular control, and functional performance rather than isolated muscle strengthening [12].

The success of the PATS program has led to increased recognition of the importance of lumbopelvic control, core stability, and functional movement patterns in hamstring injury rehabilitation [3, 12,15]. Current best practice often combines elements of both eccentric strengthening and functional agility training, recognizing that comprehensive rehabilitation should address both local muscle deficits and global movement patterns [3,12,15]. The optimal balance between these approaches may vary depending on individual athlete characteristics, injury severity, and sport-specific demands [3,12].

 

Platelet-Rich Plasma (PRP) Therapy

Platelet-rich plasma (PRP) therapy has gained popularity as an adjunctive treatment for hamstring injuries, though the evidence for its effectiveness remains mixed [3,15,25,30]. PRP involves injecting a concentrated preparation of the patient’s own platelets into the injured muscle tissue, with the goal of delivering growth factors and bioactive proteins that may accelerate healing [3,15]. The theoretical rationale for PRP is compelling, as platelets contain numerous growth factors involved in tissue repair, including platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-β), and vascular endothelial growth factor (VEGF) [15].

Clinical studies evaluating PRP for hamstring injuries have produced conflicting results [3,15,25]. Some studies have reported faster return to play and improved functional outcomes with PRP compared to standard rehabilitation alone, while others have found no significant benefit [3,15]. A systematic review of PRP for muscle injuries concluded that the evidence is insufficient to support routine use, citing methodological limitations in existing studies and significant heterogeneity in PRP preparation protocols [15]. Factors such as platelet concentration, activation method, timing of injection, and number of injections vary widely across studies, making it difficult to draw definitive conclusions [15].

Current recommendations suggest that PRP may be considered as an adjunctive treatment in select cases, particularly for high-grade injuries or in elite athletes where even small improvements in recovery time may be valuable [3,15]. However, PRP should not replace comprehensive rehabilitation, and athletes should be counseled that the evidence for its effectiveness is limited [3,15]. Further high-quality randomized controlled trials with standardized PRP protocols are needed to definitively establish the role of PRP in hamstring injury management [15,25].

Other Conservative Modalities

Numerous other conservative treatment modalities have been proposed for hamstring injuries, though the evidence supporting many of these interventions is limited [3,15,25]. Therapeutic modalities such as ultrasound, electrical stimulation, and laser therapy are commonly used in clinical practice, but systematic reviews have found insufficient evidence to support their effectiveness in accelerating recovery from hamstring injuries [15,25]. These modalities may provide symptomatic relief and are generally considered safe adjuncts to rehabilitation, but they should not be relied upon as primary treatments [15].

Manual therapy techniques, including massage, soft tissue mobilization, and myofascial release, are frequently incorporated into hamstring injury rehabilitation programs [3,15]. While these techniques may help reduce pain, improve flexibility, and enhance recovery of normal movement patterns, high-quality evidence for their effectiveness is lacking [15]. Similarly, dry needling and acupuncture have been explored as potential treatments, with some case reports suggesting benefit, but randomized controlled trials are needed to establish efficacy [30].

Nutritional interventions and supplementation have received increasing attention in sports medicine, with some evidence suggesting that adequate protein intake, vitamin D supplementation, and anti-inflammatory nutrients may support muscle healing [15]. However, specific evidence for these interventions in hamstring injury recovery is limited [15]. Emerging therapies such as shockwave therapy, hyperbaric oxygen, and blood flow restriction training are being investigated, but their role in hamstring injury management remains experimental [15,25]. Overall, the evidence base supports eccentric strengthening and progressive functional training as the primary rehabilitation interventions, with other modalities serving as potential adjuncts [3, 11,12,15, 25].

Surgery

Surgical intervention for hamstring injuries is reserved for specific clinical scenarios where conservative management is unlikely to achieve optimal outcomes [1, 2,14,17, 29]. The primary indications for surgery include: complete or near-complete avulsion of the proximal hamstring origin from the ischial tuberosity, chronic proximal hamstring tears with persistent pain and functional deficits despite adequate conservative treatment, recurrent intramuscular tendon injuries in high-level athletes, and acute high-grade musculotendinous tears in elite athletes where expedited return to sport is critical [1, 2,14,17].

Complete proximal hamstring avulsions are the most clear-cut indication for surgical repair, particularly when diagnosed acutely (within 4 weeks of injury) [2,17, 29]. These injuries typically occur during extreme hip flexion with knee extension, such as in waterskiing, gymnastics, or splits, and result in complete detachment of two or more hamstring tendons from the ischial tuberosity [2, 17]. Clinical presentation includes acute posterior thigh pain, a palpable defect at the ischial tuberosity, significant weakness, and inability to perform normal activities [2,17]. MRI confirms the diagnosis by demonstrating complete tendon retraction and fluid or hematoma at the ischial tuberosity [2,17].

Chronic proximal hamstring tears, defined as injuries present for more than 6 weeks to 3 months, may also benefit from surgical intervention, though outcomes are generally inferior to acute repairs [2,17]. Patients with chronic tears typically present with persistent posterior thigh pain, weakness, difficulty sitting, and functional limitations despite conservative treatment [2, 17]. Surgical decision-making in chronic cases must weigh the potential benefits of repair against the technical challenges of chronic surgery, including tendon retraction, muscle atrophy, and scar tissue formation [2,17]. Recurrent intramuscular tendon injuries in professional athletes represent another potential indication for surgery, with some evidence suggesting that surgical repair of the intramuscular tendon can reduce reinjury risk and expedite return to sport [14].

Proximal Hamstring Avulsion Repair

Proximal hamstring avulsion repair is the most common surgical procedure for hamstring injuries and involves reattachment of the avulsed tendons to the ischial tuberosity [2,17, 29The surgery is typically performed through a posterior approach with the patient in prone position [2,17]. The surgical technique involves identifying and mobilizing the retracted hamstring tendons, debriding the ischial tuberosity to create a bleeding bone surface, and securing the tendons back to bone using suture anchors or bone tunnels [2,17]. Most surgeons use 2-4 suture anchors placed in the ischial tuberosity, with the tendons reattached in their anatomical positions [2,17].  

Acute repairs (performed within 4 weeks of injury) are technically easier and associated with better outcomes compared to chronic repairs [2,17, 29]. In acute cases, the tendons are typically of good quality, retraction is minimal, and reattachment can be achieved with appropriate tension [2,17]. Chronic repairs are more challenging due to tendon retraction, muscle atrophy, scar tissue, and fatty infiltration [2, 17]. In chronic cases, extensive mobilization of the tendons may be required, and some surgeons use allograft augmentation or tendon transfers to bridge large gaps [2,17]. ]. A prospective cohort of patients having surgical repair for proximal avulsion by Lefevre et al. consisted of 757 patients (mean age 47.3), there was an overall 10.4% complication rate (including 5.6% re-rupture rate) [34].

Postoperative rehabilitation following proximal hamstring repair typically involves a period of protected weight-bearing and limited hip flexion to protect the repair [2,17]. Most protocols restrict hip flexion to 60-90 degrees for the first 4-6 weeks and limit weight-bearing to toe-touch or partial weight-bearing [2,17]. Progressive range of motion, strengthening, and functional training are introduced gradually over 3-6 months, with return to sport typically occurring 6-9 months after surgery [2,17]. Complications of proximal hamstring repair include infection, sciatic nerve injury, hematoma, re-rupture, and persistent weakness [2,17].

Chronic Tear Management

Management of chronic hamstring tears presents unique challenges due to tendon retraction, muscle atrophy, fatty infiltration, and scar tissue formation [2,17]. Chronic tears are typically defined as injuries present for more than 6 weeks to 3 months, though some authors use longer timeframes [2,17]. Patients with chronic proximal hamstring tears often present with persistent posterior thigh pain, weakness, difficulty sitting on hard surfaces, and functional limitations during activities requiring hip extension or knee flexion [2,17].

Surgical options for chronic proximal hamstring tears include primary repair with extensive tendon mobilization, allograft augmentation, and in severe cases, tendon transfers [2,17]. Primary repair is attempted when adequate tendon length can be achieved through mobilization, though this may require extensive dissection and release of scar tissue [2, 17]. When primary repair is not possible due to excessive retraction or poor tendon quality, allograft augmentation using Achilles tendon or other allografts can be used to bridge the gap between the retracted tendons and the ischial tuberosity [2,17]. Some surgeons have reported using autograft hamstring tendons from the contralateral leg, though this approach has obvious limitations [2].

Outcomes of chronic proximal hamstring repair are generally inferior to acute repairs, with lower rates of return to pre-injury function and higher complication rates [2,17]. Nevertheless, many patients experience significant improvement in pain and function following surgery, even if they do not return to elite athletic performance [2,17]. Patient selection is critical for chronic repairs, with the best candidates being those with significant functional limitations, persistent pain despite adequate conservative treatment, and realistic expectations about outcomes [2, 17]. Non-surgical management remains appropriate for many patients with chronic tears, particularly those with minimal symptoms or low functional demands [2,17].

Surgical Outcomes and Return to Sport

Surgical outcomes for proximal hamstring avulsion repair are generally favorable, particularly for acute repairs performed within 4 weeks of injury [2,17,29]. Multiple case series have reported good to excellent functional outcomes in 80-90% of patients following acute proximal hamstring repair, with significant improvements in strength, pain, and functional scores [2,17,29]. Return to sport rates are high, with most studies reporting that 70-90% of athletes return to their pre-injury level of competition following acute repair [2,17,29].

A systematic review of surgical outcomes for proximal hamstring avulsions found that acute repairs resulted in better outcomes than chronic repairs across all measured parameters [2,17]. Patients undergoing acute repair demonstrated greater strength recovery, higher satisfaction scores, and higher rates of return to pre-injury activity levels compared to those undergoing chronic repair [2, 17]. The time to return to sport following proximal hamstring repair typically ranges from 6-9 months, though this varies depending on injury severity, surgical technique, rehabilitation protocol, and sport-specific demands [2, 17, 29].

Complications following proximal hamstring repair are relatively uncommon but can include infection, sciatic nerve injury, hematoma, re-rupture, and persistent weakness [2, 17]. Sciatic nerve injury is a particular concern given the proximity of the nerve to the surgical field, with reported rates of transient nerve symptoms ranging from 5-15% [2,17]. Most nerve injuries are neurapraxias that resolve spontaneously within weeks to months, but permanent nerve injury can occur [2, 17]. Re-rupture rates are low following acute repair (typically <5%) but higher following chronic repair [2,17]. Overall, surgical repair of proximal hamstring avulsions is a safe and effective treatment for appropriately selected patients, with high rates of functional recovery and return to sport [2,17,29].

Distal Biceps Femoris – Musculotendinous T Junction Injuries

There is an emerging practice of surgical intervention for biceps femoris myotendinous injuries involving the T-junction (See Figure 5).  The T-junction represents the meeting point of the BFLH and BFSH tendons.  The goal is to reduce the high rates of reinjury with this type of injury. 

Figure 6 – T junction in cross section between BFSH and BFLH

One case series of 34 professional athletes with BAMIC grade IIIb and IIIc injuries involving the biceps femoris were included for surgical repair.  The authors report poor correlation between MRI and operative appearance of T junction and  ~12 weeks return to play postoperative timeline. No significant complications were reported. [35]  See article on T junction injuries:  https://sportmedschool.com/biceps-femoris-t-junction-injuries/

Conclusion

Hamstring injuries remain one of the most common and challenging problems in sports medicine, affecting athletes across a wide range of sports and competition levels. This comprehensive review has synthesized current evidence on the anatomy, mechanisms, diagnostic imaging, treatment modalities, and return-to-play protocols for hamstring injuries. The hamstring muscle group’s unique anatomical characteristics—including its biarticular nature, long muscle fibers, and vulnerability during eccentric loading—predispose it to injury during high-speed running and extreme stretching activities [2,7,11,18].

Modern MRI-based grading systems, including the British Athletics Muscle Injury Classification, Peetrons classification, and MLG-R system, provide valuable prognostic information that guides treatment planning and return-to-play decisions [7,18,23,24]. These classification systems have demonstrated that injury location, particularly involvement of the proximal free tendon or intramuscular tendon, is a critical determinant of recovery time [7,18]. However, the proliferation of different classification systems highlights the need for standardization and further validation research [7,18, 23].

Non-surgical management remains the cornerstone of treatment for the vast majority of hamstring injuries, with strong evidence supporting eccentric strengthening, progressive functional training, and criteria-based return-to-play protocols [3, 8,11,12,15, 26]. The high recurrence rate of hamstring injuries (14-63%) underscores the importance of comprehensive rehabilitation that addresses not only local muscle deficits but also modifiable risk factors such as strength imbalances, lumbopelvic control, and running mechanics [1,11,15, 22, 25]. Emerging treatments such as PRP therapy show promise but require further high-quality research to establish their role in clinical practice [3,15].

Surgical intervention is reserved for complete proximal avulsions, chronic tears with persistent functional deficits, and select cases of recurrent injuries in elite athletes [1,2,14, 17]. Acute surgical repair of proximal hamstring avulsions yields excellent outcomes, with 80-90% of patients achieving good to excellent functional results and high rates of return to sport [2, 17, 29]. However, chronic repairs are more challenging and associated with inferior outcomes, emphasizing the importance of early diagnosis and appropriate surgical referral [2,17].

Future research priorities include: validation of return-to-play criteria to reduce reinjury risk, standardization of MRI classification systems, identification of modifiable risk factors for primary and recurrent injury, optimization of rehabilitation protocols, and evaluation of emerging treatments through high-quality randomized controlled trials [15,25,26,30]. Additionally, research into the biomechanical and neuromuscular factors contributing to hamstring injury, as well as the development of effective injury prevention programs, will be critical for reducing the burden of these injuries in athletic populations [11,15,22,25].

In conclusion, optimal management of hamstring injuries requires a comprehensive, evidence-based approach that integrates accurate diagnosis, appropriate treatment selection, progressive rehabilitation, and individualized return-to-play decision-making. By applying the principles and evidence reviewed in this article, clinicians can optimize outcomes for athletes with hamstring injuries and minimize the risk of recurrence [1, 3, 8, 11,15, 26].

Dr. Neil Dilworth (June 15, 2026  PR KA )

References

[1] Chang, D., Boulos, A., Elattar, O., & Ashkani-Esfahani, S. (2020). Management of hamstring injuries: current concepts review. Journal of Bone and Joint Surgery-British Volume, 102(10). https://doi.org/10.1302/0301-620X.102B10.BJJ-2020-1210.R1

[2] Arner, J. W., Bradley, J. P., & McCulloch, P. C. (2025). Hamstring injuries in athletes: Anatomy, pathology, and treatment. Journal of The American Academy of Orthopaedic Surgeons. https://doi.org/10.5435/jaaos-d-24-01162

[3] Hickey, J. T., Timmins, R. G., Maniar, N., Williams, M. D., & Opar, D. A. (2021). Current clinical concepts: hamstring strain injury rehabilitation. Journal of Athletic Training. https://doi.org/10.4085/1062-6050-0707.20

[4] Ahmad, C. S., Redler, L. H., Ciccotti, M. G., Maffulli, N., Longo, U. G., & Bradley, J. (2013). Evaluation and Management of Hamstring Injuries. American Journal of Sports Medicine, 41(12). https://doi.org/10.1177/0363546513487063

[5] Hoy, G., Hoy, K., & Mansour, R. (2024). Hamstring Injuries: A Paradigm for Return to Play. Seminars in Musculoskeletal Radiology, 28(1). https://doi.org/10.1055/s-0043-1778027

[6] Chu, S. K., & Rho, M. E. (2016). Hamstring Injuries in the Athlete: Diagnosis, Treatment, and Return to Play. Current Sports Medicine Reports, 15(3). https://doi.org/10.1249/JSR.0000000000000264

[7] Kerkhoffs, G. M., van Es, N., Wieldraaijer, T., Sierevelt, I. N., Ekstrand, J., & van Dijk, C. N. (2013). Diagnosis and prognosis of acute hamstring injuries in athletes. Knee Surgery, Sports Traumatology, Arthroscopy, 21(2). https://doi.org/10.1007/S00167-012-2055-X

[8] Erickson, L. N., & Sherry, M. A. (2017). Rehabilitation and return to sport after hamstring strain injury. Journal of Sport and Health Science, 6(3). https://doi.org/10.1016/J.JSHS.2017.04.001

[9] Takara, T., & Silvers-Granelli, H. (2014). Midsubstance Hamstring Injuries in the Athlete. In Hamstring and Quadriceps Injuries in Athletes (pp. 43-56). https://doi.org/10.1007/978-1-4899-7510-2_4

[10] Silvers-Granelli, H. J., Cohen, M., Espregueira-Mendes, J., Mandelbaum, B., Neyret, P., & Cloke, D. (2021). Hamstring muscle injury in the athlete: state of the art. Journal of ISAKOS, 2(3). https://doi.org/10.1136/JISAKOS-2017-000145

[11] Heiderscheit, B. C., Sherry, M. A., Silder, A., Chumanov, E. S., & Thelen, D. G. (2010). Hamstring strain injuries: recommendations for diagnosis, rehabilitation, and injury prevention. Journal of Orthopaedic & Sports Physical Therapy, 40(2). https://doi.org/10.2519/JOSPT.2010.3047

[12] Sherry, M. A., & Best, T. M. (2015). Rehabilitation of acute hamstring strain injuries. Clinics in Sports Medicine, 34(2). https://doi.org/10.1016/J.CSM.2014.12.009

[13] Clanton, T. O., & Coupe, K. J. (1998). Hamstring strains in athletes: diagnosis and treatment. Journal of The American Academy of Orthopaedic Surgeons, 6(4). https://doi.org/10.5435/00124635-199807000-00005

[14] Sonnery-Cottet, B., Saithna, A., Quelard, B., Daggett, M., Borade, A., Ouanezar, H., Thaunat, M., & Blakeney, W. G. (2015). Surgical Management of Recurrent Musculotendinous Hamstring Injury in Professional Athletes. Orthopaedic Journal of Sports Medicine, 3(9). https://doi.org/10.1177/2325967115606393

[15] Arner, J. W., McClincy, M. P., Bradley, J. P., & Hamstring Injury Study Group. (2019). Hamstring Injuries in Athletes: Evidence-based Treatment. Journal of The American Academy of Orthopaedic Surgeons, 27(23). https://doi.org/10.5435/JAAOS-D-18-00741

[16] Khattak, M. J., Iqbal, T., Akhtar, S., & Batool, S. (2021). Hamstring Injury Recurrence and Prevention: A Review. Life Sciences, 1(1). https://doi.org/10.37185/LNS.1.1.188

[17] Made, C., Reurink, G., Gouttebarge, V., Tol, J. L., & Kerkhoffs, G. (2016). Proximal Hamstring Injuries (ICL 8). In Muscle Injuries in Sport Athletes (pp. 83-95). https://doi.org/10.1007/978-3-662-49114-0_8

[18] Marrero, L., Patel, D. B., Lesniak, B., & White, E. A. (2025). MRI and US in hamstring sports injury assessment: Anatomy, imaging findings, and mechanisms of injury. Radiographics, 45(1). https://doi.org/10.1148/rg.240061

[19] Ma, Y. (2025). Prevention and Treatment of Hamstring Injuries. Theoretical and Natural Science, 2025. https://doi.org/10.54254/2753-8818/2025.au26749

[20] Carlson, C. (2008). The natural history and management of hamstring injuries. Current Reviews in Musculoskeletal Medicine, 1(2). https://doi.org/10.1007/S12178-007-9018-8

[21] Hickey, J. T., Timmins, R. G., Maniar, N., Williams, M. D., & Opar, D. A. Hamstring strain injury rehabilitation.

[22] Shield, A. J., & Bourne, M. N. (2012). Hamstring strain injuries: factors that lead to injury and re-injury.

[23] Valle, X., Alentorn-Geli, E., Tol, J. L., Hamilton, B., Garrett, W. E., Pruna, R., Til, L., Gutierrez, J. A., Alomar, X., Balius, R., Malliaropoulos, N. G., Monllau, J. C., Whiteley, R., Witvrouw, E., Samuelsson, K., & Rodas, G. (2022). Return to Play Prediction Accuracy of the MLG-R Classification System for Hamstring Injuries in Football Players: A Machine Learning Approach. Sports Medicine, 52(8). https://doi.org/10.1007/s40279-022-01672-5

[24] Hallén, A., & Ekstrand, J. (2014). Return to play following muscle injuries in professional footballers. Journal of Sports Sciences, 32(13). https://doi.org/10.1080/02640414.2014.905695

[25] Brukner, P. (2015). Hamstring injuries: prevention and treatment—an update. British Journal of Sports Medicine, 49(19). https://doi.org/10.1136/BJSPORTS-2014-094427

[26] Rudisill, S. S., Varady, N. H., & Kucharik, M. P. (2021). Evidence-based management and factors associated with return to play after acute hamstring injury in athletes: a systematic review. Orthopaedic Journal of Sports Medicine, 9(11). https://doi.org/10.1177/23259671211053833

[27] Lin, Y. (2023). Diagnosis and management of acute hamstring strain injury. Proceedings of SPIE, 12669. https://doi.org/10.1117/12.2669334

[28] Gudigar, A., Choi, Y. S., & Kim, J. Y. (2026). Complete avulsion of the proximal hamstring tendon in a young gymnast: a case report. Journal of Trauma and Injury, 39(1). https://doi.org/10.20408/jti.2025.0121

[29] Kuske, B., Hamilton, D. F., Pattle, S. B., & Simpson, A. H. R. W. (2016). Patterns of hamstring muscle tears in the general population: a systematic review. PLOS ONE, 11(4). https://doi.org/10.1371/JOURNAL.PONE.0152855

[30] Horst, N., Smits, D. W., Petersen, J., Goedhart, E. A., Backx, F. J. G., & Huisstede, B. M. A. (2016). Return to Play After Hamstring Injuries: A Qualitative Systematic Review of Definitions and Criteria. Sports Medicine, 46(6). https://doi.org/10.1007/S40279-015-0468-7

[31] – Cadaver image of Pes Anserine – Dr. Jorge Chahla – https://www.facebook.com/jachahla/photos/a.922437454613919/1584975915026733/?id=902964746561190

[32]  Hu Y, Raja A. Anatomy, Bony Pelvis and Lower Limb, Hamstring Muscle. [Updated 2026 Jan 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK546688/

[33] S. Grange et al., “Location of Hamstring Injuries Based on Magnetic Resonance Imaging: A Systematic Review,” Sports Health: A Multidisciplinary Approach, vol. 15, no. 1, pp. 111–123, Feb. 2022, doi: 10.1177/19417381211071010.

[34] Lefèvre N, Moussa MK, Valentin E, Freiha K, Bohu Y, Gerometta A, Khiami F, Grimaud O, Meyer A, Hardy A. Risk Factors for Complications After Proximal Hamstring Avulsion Injury: Analysis of 757 Patients From the PHAS Cohort. Orthop J Sports Med. 2026 Mar 27;14(3):23259671261418679. doi: 10.1177/23259671261418679. PMID: 41918719; PMCID: PMC13033848.

[35] Kayani B, Ayuob A, Begum F, Singh S, Haddad FS. Surgical Repair of Distal Musculotendinous T Junction Injuries of the Biceps Femoris. Am J Sports Med. 2020 Aug;48(10):2456-2464. doi: 10.1177/0363546520938679. PMID: 32736504.

[37] Hirahata, T., Ono, T., Terada, M., Ohmi, Y., & Takahashi, K. (2025). Role of Ultrasonography and MRI in Acute Hamstring Strains: Diagnostic and Prognostic Insights. Preprints, 2025022282. https://doi.org/10.20944/preprints202502.2282.v1

[38] Connell, D. A., Schneider-Kolsky, M. E., Hoving, J. L., Malara, F., Buchbinder, R., Koulouris, G., Burke, F., & Bass, C. (2004). Longitudinal Study Comparing Sonographic and MRI Assessments of Acute and Healing Hamstring Injuries. American Journal of Roentgenology, 183(4), 975-984. https://doi.org/10.2214/AJR.183.4.1830975

[39] Lefèvre, N., Bohu, Y., Klouche, S., Lefevre, J., & Herman, S. (2024). Magnetic resonance imaging should be the first‐line imaging modality for investigating suspected proximal hamstring avulsion injuries. Knee Surgery, Sports Traumatology, Arthroscopy, 32(7), 1789-1796. https://doi.org/10.1002/ksa.12258

[40] Wangensteen, A., Almusa, E., Boukarroum, S., Farooq, A., Hamilton, B., Whiteley, R., & Guermazi, A. (2018). New MRI muscle classification systems and associations with return to sport after acute hamstring injuries: a prospective study. European Radiology, 28(7), 3532-3541. https://doi.org/10.1007/S00330-017-5125-0

[41] Petersen, J., Thorborg, K., Nielsen, M. B., Budtz-Jørgensen, E., & Hölmich, P. (2014). The Diagnostic and Prognostic Value of Ultrasonography in Soccer Players With Acute Hamstring Injuries. American Journal of Sports Medicine, 42(2), 399-404. https://doi.org/10.1177/0363546513512779

[42] Pedret, C. (2022). Hamstring Muscle Injuries: MRI and Ultrasound for Diagnosis and Prognosis. Journal of the Belgian Society of Radiology, 106(1), 1-12. https://doi.org/10.5334/jbsr.2617