Prognosticating Return-To-Play Time Following a Hamstring Strain Injury Using Early Flexibility Asymmetry and Musculoskeletal Ultrasound Imaging Outcomes: An Exploratory Study Among Canadian University Football Players.

OBJECTIVE: Identify key flexibility and point-of-care musculoskeletal ultrasound (POCUS) measures for prognosticating return-to-play (RTP) following a first hamstring strain injury (HSI) and informing the clinical decision-making process. DESIGN: Exploratory prospective cohort study. SETTING: Sport medicine and rehabilitation clinic of a Canadian university. PARTICIPANTS: One hundred and sixty-seven elite Canadian university football athletes followed over 5 seasons. INTERVENTIONS: Clinical and POCUS measures collected within 7 days after HSI and preseason clinical measures. MAIN OUTCOME MEASURES: Active knee extension (AKE) and Straight Leg Raise (SLR) to quantify hamstring flexibility, POCUS-related outcomes to characterize tissue alteration, and RTP until full sport resumption were documented (categorized as Early [1-40 days] or Late [>40 days] RTP). RESULTS: A total of 19 and 14 athletes were included in the Early RTP (mean RTP = 28.84 ± 8.62 days) and Late RTP groups (mean 51.93 ± 10.54 days), respectively, after having been diagnosed with a first HSI. For the clinical results, height and a greater flexibility asymmetry measure with the AKE or SLR when compared with both ipsilateral preseason and acute contralateral values significantly increases the chance of facing a long delay before returning to play (ie, RTP). For the POCUS-related results, the Peetrons severity score, extent of the longitudinal fibrillary alteration, and novel score lead to similar results. CONCLUSIONS: Early hamstring flexibility asymmetry following acute HSI, particularly the AKE, along with some POCUS-related measures are valuable in prognosticating late RTP following among Canadian university football athletes.

Ease of Use and Usefulness of a Newly Developed Mobile App to Monitor Pain and Adherence Among Individuals With an Achilles Tendinopathy Engaged in a Rehabilitation Program.

OBJECTIVE: Assess the perceived ease of use and perceived usefulness of a newly developed mobile app. DESIGN: Descriptive survey study. SETTING: Home-based rehabilitation program. PARTICIPANTS: A group of 31 adults with a symptomatic Achilles tendinopathy. INTERVENTION: A mobile app was developed to support the deployment of the 12-week active exercise-based rehabilitation program and facilitate the monitoring of exercise adherence twice daily and the assessment of localized Achilles tendon pain using a numeric pain rating scale on a weekly basis. MAIN OUTCOME MEASURES: Results of an online survey encompassing 10 questions, each rated on a 5-point Likert scale (5 = strongly agree; 1 = strongly disagree). RESULTS: Nearly all participants agreed that the mobile app was easy to install (96.4%) and easy to use (100%). Most participants confirmed that no technical issues were encountered (96.4%). The instructional videos were deemed helpful in properly performing the recommended exercises (85.7%), whereas the prompts sent via text message were found to promote adherence (88.9%). The design and appearance of the mobile app were appreciated by a lower percentage of participants (75%). CONCLUSION: Participants confirmed the ease of use and usefulness of the newly developed mobile app and demonstrated a positive attitude toward its use.

Diagnosing, Managing, and Supporting Return to Work of Adults With Rotator Cuff Disorders: A Clinical Practice Guideline.

OBJECTIVE: To develop a clinical practice guideline covering the assessment, management, and return to work of adults with rotator cuff disorders. DESIGN: Clinical practice guideline. METHODS: Using systematic reviews, appraisal of the literature, and an iterative approach to obtain consensus from key stakeholders, clinical recommendations and algorithms were developed in the context of the health care system and work environment of the province of Quebec (Canada). RESULTS: Recommendations (n = 73) and clinical decision algorithms (n = 3) were developed to match the objectives. The initial assessment should include the patient's history, a subjective assessment, and a physical examination. Diagnostic imaging is only necessary in select circumstances. Acetaminophen, nonsteroidal anti-inflammatory drugs, and injection therapies may be useful to reduce pain in the short term. Clinicians should prescribe an active and task-oriented rehabilitation program (exercises and education) to reduce pain and disability in adults with rotator cuff disorders. Subacromial decompression is not recommended to treat rotator cuff tendinopathy. Surgery is appropriate for selected patients with a full-thickness rotator cuff tear. A return-to-work plan should be developed early, in collaboration with the worker and other stakeholders, and must combine multiple strategies to promote return to work. CONCLUSION: This clinical practice guideline was developed to assist the multidisciplinary team of clinicians who provide health care for adults with a rotator cuff disorder. The CPG guides clinical decisionmaking for diagnosis and treatment, and planning for successful return to work. J Orthop Sports Phys Ther 2022;52(10):647-664. Epub: 27 July 2022. doi:10.2519/jospt.2022.11306.

To What Extent Do Musculoskeletal Ultrasound Biomarkers Relate to Pain, Flexibility, Strength, and Function in Individuals With Chronic Symptomatic Achilles Tendinopathy?

Introduction: Achilles tendinopathy (AT) is a chronic musculoskeletal pathology best evaluated by ultrasound imaging. This cross-sectional study aimed at better understanding the relationship between musculoskeletal ultrasound biomarkers (MUBs) of Achilles tendon and localized pain, ankle flexibility, ankle strength, and functional abilities. Method: Forty-one participants with unilateral midportion chronic AT had their tendon images analyzed bilaterally in the longitudinal and transverse planes. The Victorian Institute of Sport Assessment-Achilles questionnaire (VISA-A) and Lower Extremity Functional Scale (LEFS) assessed pain and function, respectively, during standing and walking-related activities. Ankle flexibility was evaluated by weight-bearing lunge tests, while ankle isometric peak strength was measured using an instrumented dynamometer. Achilles tendon ultrasonographic images were analyzed using geometric (thickness), composition (echogenicity), and texture (homogeneity) MUBs. Discriminative validity was evaluated using paired Student's t-tests to compare MUBs between symptomatic and asymptomatic sides. Predictive validity was evaluated by computing the Pearson product-moment correlations coefficient between MUBs and pain, ankle flexibility, ankle strength, and function. Results: Significant differences were found in MUBs between the symptomatic and asymptomatic sides, confirming the discriminative validity of the selected MUBs. On the symptomatic side, thickness was found 29.9% higher (p < 0.001), echogenicity 9.6% lower (p < 0.001), and homogeneity 3.8% higher (p = 0.001) when compared with the asymptomatic side. However, predictive validity was scarcely confirmed, as most of the correlation coefficients were found negligible for the associations investigated between MUBs with localized pain, ankle flexibility, strength, and function. Only 14 statistically significant low to moderate associations were found, with negative and positive correlations ranging between -0.31 and -0.55 and between 0.34 and 0.54, respectively. Discussion: Musculoskeletal ultrasound biomarkers have a clinical utility in visualizing in vivo tendon integrity and diagnosing AT. MUBs should be valued as part of a comprehensive neuro-musculoskeletal assessment as they complement pain, flexibility, strength, and function measures. Altogether, they may inform the development and monitoring of a personalized rehabilitation treatment plan.

Effects of a preoperative neuromobilization program offered to individuals with carpal tunnel syndrome awaiting carpal tunnel decompression surgery: A pilot randomized controlled study.

STUDY DESIGN: Pilot randomized controlled trial with parallel groups. INTRODUCTION: Engaging individuals with carpal tunnel syndrome (CTS) awaiting carpal tunnel decompression surgery in a preoperative rehabilitation program may mitigate pain and sensorimotor impairments, enhance functional abilities before surgery, and improve postoperative outcomes. PURPOSE OF THE STUDY: To assess the feasibility and the efficacy of a novel preoperative neuromobilization exercise program (NEP). METHODS: Thirty individuals with CTS were randomly allocated into a four-week home-based neuromobilization exercise group or a standard care group while awaiting surgery. Outcome measures included feasibility (ie, recruitment, attrition, adherence, satisfaction, and safety) and efficacy metrics (ie, median nerve integrity and neurodynamics, tip pinch grip, pain, and upper limb functional abilities) collected before (ie, at the baseline and about four weeks later) and four weeks after surgery. RESULTS: Thirty individuals with CTS were recruited (recruitment rate = 11.8%) and 25 completed the study (attrition rate = 16.7%). Adherence (94%) and satisfaction with the program (eg, enjoy the exercises and likeliness to repeat the NEP (≥4.2/5) were high and no serious adverse event was reported. NEP-related immediate pre- and post-surgery beneficial effects on pain interference were documented (P = .05, η2 = .10), whereas an overall increased neurodynamics (P = .04, η2 = .11) and decreased pain severity (P = .01, η2 = .21) were observed. DISCUSSION: Engaging in the proposed NEP has limited beneficial effect as a stand-alone intervention on pre- and post-surgery outcomes for individuals with CTS. Expanding the program's content and attribute by adding other components including desensitization maneuvers and novel therapies promoting corticospinal plasticity is recommended. CONCLUSION: A preoperative NEP completed by individuals with CTS awaiting surgery is feasible, acceptable, and safe. However, given the limited beneficial effectsof the program, revision of its content and attributes is recommended before proceeding to large-scale trials.

Intra-articular injections of platelet-rich plasma in symptomatic knee osteoarthritis: a consensus statement from French-speaking experts.

PURPOSE: There has been much debate regarding the use of intra-articular injections of platelet-rich plasma (PRP) as symptomatic treatment for knee osteoarthritis. The objective of this consensus was to develop guidelines for PRP injections in knee osteoarthritis according to the French National Authority for Health recommendations. METHODS: Fifteen physicians from different French-speaking countries (10 rheumatologists, 4 specialists in rehabilitation and sports medicine and 1 radiologist) were selected for their expertise in the areas of PRP and osteoarthritis. A comprehensive literature review was conducted on Medline including all published therapeutic trials, open studies, meta-analysis and systematic reviews focusing on the effects of PRP in knee OA, as well as fundamental studies concerning the characteristics of the various types of PRP and their mechanisms, indexed before April 2019. Using the method recommended by the French National Authority for Health inspired by the Delphi consensus process, 25 recommendations were finally retained and evaluated. The recommendations were classified as appropriate or not appropriate, with strong or relative agreement, or uncertain if a consensus was not achieved. RESULTS: Among the 25 recommendations selected, the main ones are the following: (1) Intra-articular injections of PRP are an effective symptomatic treatment for early to moderate knee osteoarthritis. This recommendation was considered appropriate with a relative agreement (Median = 8; rank = 6-9). Level of evidence 1A. (2) A PRP treatment sequence in knee osteoarthritis may include 1-3 injections. This recommendation was considered appropriate with a strong agreement (Median = 9; rank = 7-9). Level of evidence 1A. (3) Leucocytes-poor PRP should be preferred in knee osteoarthritis. This recommendation was considered appropriate with a relative agreement (Median = 8; rank = 5-9). Level of evidence 5. (4) Intra-articular PRP knee injections should be performed under ultrasound or fluoroscopic guidance. This recommendation was considered uncertain with no consensus (Median = 8; rank = 3-9). Level of evidence 5. (5) PRP should not be mixed with an anesthetic or intra-articular corticosteroid. This recommendation was considered appropriate with a relative agreement (Median = 9; rank = 6-9). Level of evidence 5 CONCLUSION: Those 25 recommendations should standardize and facilitate the use of IA PRP injections, which are considered by experts as an effective treatment especially in early or moderate knee OA. Although a strong or relative agreement from the experts was obtained for most of the recommendations, many of them had a very low level of evidence (Level 5) and were principally based on the clinical experience of the experts.

Proposing a Minimal Data Set of Musculoskeletal Ultrasound Imaging Biomarkers to Inform Clinical Practice: An Analysis Founded on the Achilles Tendon.

Tendon integrity can be described using a wide range of biomarkers via specialized analysis software for images recorded by musculoskeletal ultrasonography. This study proposes a minimal biomarker data set to characterize Achilles tendon ultrasound images and to differentiate between symptomatic and asymptomatic Achilles tendon images. Forty-one individuals with unilateral Achilles tendinopathy and 35 healthy controls had their Achilles tendon images recorded bilaterally by ultrasonography in the longitudinal and transverse planes. A set of 22 biomarkers, organized around three dimensions (geometric, composition and texture), were computed in each plane. A symmetry index, reflecting relative side differences, was compared between groups and analyzed through principal component analysis to isolate biomarkers that best explained data variance. A specific minimal data set was identified by linear regression in the longitudinal (mean thickness, echogenicity, variance and homogeneity at 90°) and transverse (mean thickness, echogenicity and mean homogeneity) planes to characterize and differentiate Achilles tendon integrity.

Shoulder Rotator Cuff Disorders: A Systematic Review of Clinical Practice Guidelines and Semantic Analyses of Recommendations.

OBJECTIVES: To perform a systematic review of clinical practice guidelines (CPGs) and semantic analysis of specific clinical recommendations for the management of rotator cuff disorders in adults. DATA SOURCES: A systematic bibliographic search was conducted up until May 2018 in Medline, Embase, and Physiotherapy Evidence Database, or PEDro, databases, in addition to 12 clinical guidelines search engines listed on the Appraisal of Guidelines for Research and Evaluation (AGREE) website. STUDY SELECTION: Nine CPGs on the management of rotator cuff disorders in adults or workers, available in English or French, and published from January 2008 onward, were included and screened by 2 independent reviewers. DATA EXTRACTION: CPG methodology was assessed with the AGREE II checklist. A semantic analysis was performed to compare the strength of similar recommendations based on their formulation. The recommendations were categorized in a standardized manner considering the following 4 levels: "essential," "recommended," "may be recommended," and "not recommended." DATA SYNTHESIS: Methodological quality was considered high for 3 CPGs and low for 6. All CPGs recommended active treatment modalities, such as an exercise program in the management of rotator cuff disorders. Acetaminophen or nonsteroidal anti-inflammatory drug prescriptions and corticosteroid injections were presented as modalities that may be recommended to decrease pain. Recommendations related to medical imagery and surgical opinion varied among the guidelines. The most commonly recommended return-to-work strategies included intervening early, use of a multidisciplinary approach, and adaptation of work organization. CONCLUSIONS: Only 3 CPGs were of high quality. The development of more rigorous CPGs is warranted.

Multiple platelet-rich plasma preparations can solubilize freeze-dried chitosan formulations to form injectable implants for orthopedic indications.

BACKGROUND: Platelet-rich plasma (PRP) has been used to solubilize freeze-dried chitosan (CS) formulations to form injectable implants for tissue repair. OBJECTIVE: To determine whether the in vitro performance of the formulations depends on the type of PRP preparation used to solubilize CS. METHODS: Formulations containing 1% (w/v) CS with varying degrees of deacetylation (DDA 80.5-84.8%) and number average molar mass (Mn 32-55 kDa), 1% (w/v) trehalose and 42.2 mM calcium chloride were freeze-dried. Seven different PRP preparations were used to solubilize the formulations. Controls were recalcified PRP. RESULTS: CS solubilization was achieved with all PRP preparations. CS-PRP formulations were less runny than their corresponding PRP controls. All CS-PRP formulations had a clotting time below 9 minutes, assessed by thromboelastography, while the leukocyte-rich PRP controls took longer to coagulate (>32 min), and the leukocyte-reduced PRP controls did not coagulate in this dynamic assay. In glass culture tubes, all PRP controls clotted, expressed serum and retracted (43-82% clot mass lost) significantly more than CS-PRP clots (no mass lost). CS dispersion was homogenous within CS-PRP clots. CONCLUSIONS: In vitro performance of the CS-PRP formulations was comparable for all types of PRPs assessed.

Is ultrasound-guided lavage an effective intervention for rotator cuff calcific tendinopathy? A systematic review with a meta-analysis of randomised controlled trials.

BACKGROUND: Rotator cuff calcific tendinopathy is characterised by the deposition of hydroxyapatite crystals in one of the rotator cuff tendons and can be managed by ultrasound-guided lavage. However, evidence regarding the efficacy of ultrasound-guided lavage for rotator cuff calcific tendinopathy remains inconclusive. The aim of this systematic review and meta-analysis is to update the available evidence on the efficacy of ultrasound-guided lavage in adults with rotator cuff calcific tendinopathy. METHODS: A literature search was conducted up to April 2018 in four bibliographic databases to identify randomised control trials that compared ultrasound-guided lavage alone with other interventions to treat rotator cuff calcific tendinopathy. Randomised control trials were assessed with the Cochrane Risk of Bias Tool. Meta-analyses and/or qualitative synthesis of the evidence were performed. RESULTS: Three randomised control trials were included. Pooled results for pain (n=226) indicated that ultrasound-guided lavage may significantly decrease pain when compared with shockwave therapy, with a mean difference of -1.98 out of 10 points (95% CI -2.52 to -1.45) in the short term and of -1.84 (95% CI -2.63 to -1.04) in the long term. Based on one trial (n=25), ultrasound-guided lavage significantly improved function when compared with shockwave therapy (p<0.05). Based on another trial (n=48), the addition of ultrasound-guided lavage to a corticosteroid injection significantly improves function in the long term (p<0.05). CONCLUSION: For individuals with rotator cuff calcific tendinopathy, low-quality evidence suggests that ultrasound-guided lavage is more effective than shockwave therapy or a corticosteroid injection alone. Future trials could modify the present conclusions. TRIAL REGISTRATION NUMBER: CRD42018095858.

Comparison of the 3 Different Injection Techniques Used in a Randomized Controlled Study Evaluating a Cross-Linked Sodium Hyaluronate Combined With Triamcinolone Hexacetonide (Cingal) for Osteoarthritis of the Knee: A Subgroup Analysis.

A recent trial demonstrated that patients with knee osteoarthritis treated with a sodium hyaluronate and corticosteroid combination (Cingal) experienced greater pain reductions compared with those treated with sodium hyaluronate alone (Monovisc) or saline up to 3 weeks postinjection. In this study, injections were administered by 1 of 3 approaches; however, there is currently no consensus on which, if any, of these techniques produce a more favorable outcome. To provide additional insight on this topic, the results of the previous trial were reanalyzed to determine whether (1) the effect of Cingal was significant within each injection technique and (2) pain reductions were similar between injection techniques across all treatment groups. Greater pain reductions with Cingal up to 3 weeks were only significant in the anteromedial subgroup. Across all therapies, both the anteromedial and anterolateral techniques demonstrated significantly greater pain reductions than the lateral midpatellar approach at 18 and 26 weeks.

Cost-Utility of a Single-Injection Combined Corticosteroid-Hyaluronic Acid Formulation vs a 2-Injection Regimen of Sequential Corticosteroid and Hyaluronic Acid Injections.

Research has shown early and sustained relief with a combination therapy of a corticosteroid (CS) and hyaluronic acid (HA) in knee osteoarthritis (OA) patients. This can be administered via a single injection containing both products or as separate injections. The former may be more expensive when considering only product cost, but the latter incurs the additional costs and time of a second procedure. The purpose of this study was to compare the cost-utility of the single injection with the 2-injection regimen. The results of this analysis revealed that the single-injection formulation of a CS and HA may be cost-effective, assuming a willingness-to-pay of $50 000 per quality-adjusted life year gained, for symptomatic relief of OA symptoms. This treatment may also be more desirable to patients who find injections to be inconvenient or unpleasant.

Comparison of longitudinal excursion of a nerve-phantom model using quantitative ultrasound imaging and motion analysis system methods: A convergent validity study.

BACKGROUND: Quantitative ultrasound imaging is gaining popularity in research and clinical settings to measure the neuromechanical properties of the peripheral nerves such as their capability to glide in response to body segment movement. Increasing evidence suggests that impaired median nerve longitudinal excursion is associated with carpal tunnel syndrome. To date, psychometric properties of longitudinal nerve excursion measurements using quantitative ultrasound imaging have not been extensively investigated. METHODS: This study investigates the convergent validity of the longitudinal nerve excursion by comparing measures obtained using quantitative ultrasound imaging with those determined with a motion analysis system. A 38-cm long rigid nerve-phantom model was used to assess the longitudinal excursion in a laboratory environment. The nerve-phantom model, immersed in a 20-cm deep container filled with a gelatin-based solution, was moved 20 times using a linear forward and backward motion. Three light-emitting diodes were used to record nerve-phantom excursion with a motion analysis system, while a 5-cm linear transducer allowed simultaneous recording via ultrasound imaging. RESULTS: Both measurement techniques yielded excellent association (r = 0.99) and agreement (mean absolute difference between methods = 0.85 mm; mean relative difference between methods = 7.48 %). Small discrepancies were largely found when larger excursions (i.e. > 10 mm) were performed, revealing slight underestimation of the excursion by the ultrasound imaging analysis software. CONCLUSION: Quantitative ultrasound imaging is an accurate method to assess the longitudinal excursion of an in vitro nerve-phantom model and appears relevant for future research protocols investigating the neuromechanical properties of the peripheral nerves.

Determinants and predictors of absenteeism and return-to-work in workers with shoulder disorders.

BACKGROUND: Shoulder disorders lead to substantial productivity loss and determinants and predictors of sick leave are poorly known. OBJECTIVE: To perform a systematic review on determinants and predictors of sick leave and delayed return-to-work (RTW) in workers with shoulder disorders. METHODS: A systematic literature search was conducted and we included studies on workers with shoulder disorders that contained information on determinants or predictors for sick leave or RTW, The risk of bias of included studies was evaluated with a validated tool. RESULTS: Eight studies were included and four had a high risk of bias. The only determinants that were found significantly associated with delayed RTW or sickness absence in more than one study were an atraumatic history, disease severity and previous sickness absence. A clinical prediction rule was developed to predict sick leave in one study and included the following predictors: a longer duration of sick leave prior to consultation, higher shoulder pain, strain/overuse in usual activities and psychological complaints. CONCLUSION: Several determinants or predictors were identified in the present review, but there is currently inconsistent evidence on the role of any determinants or predictors of work absence or delayed RTW for workers with a shoulder disorder. More methodologically sound studies are needed.

Quantitative ultrasound imaging of Achilles tendon integrity in symptomatic and asymptomatic individuals: reliability and minimal detectable change.

BACKGROUND: Quantifying the integrity of the Achilles tendon (AT) is a rehabilitation challenge. Adopting quantitative ultrasound measurements (QUS measurements) of the AT could fill this gap by 1) evaluating the test-retest reliability and accuracy of QUS measurements of the AT; 2) determining the best protocol for collecting QUS measurements in clinical practice. METHODS: A total of 23 ATs with symptoms of Achilles tendinopathy and 63 asymptomatic ATs were evaluated. Eight images were recorded for each AT (2 visits × 2 evaluators × 2 images). Multiple sets of QUS measurements were taken: geometric (thickness, width, area), first-order statistics (computed from a grayscale histogram distribution: echogenicity, variance, skewness, kurtosis, entropy) and texture features (computed from co-occurrence matrices: contrast, energy, homogeneity). A generalizability study quantified the reliability and standard error of measurement (accuracy) of each QUS measurement, and a decision study identified the best measurement taking protocols. RESULTS: Geometric QUS measurements demonstrated excellent accuracy and reliability. QUS measurements computed from the grayscale histogram distribution revealed poor accuracy and reliability. QUS measurements derived from co-occurrence matrices showed variable accuracy and moderate to excellent reliability. In clinical practice, using an average of the results of three images collected by a single evaluator during a single visit is recommended. CONCLUSIONS: The use of geometric QUS measurements enables quantification of AT integrity in clinical practice and research settings. More studies on QUS measurements derived from co-occurrence matrices are warranted.

Determinants of Return to Play After the Nonoperative Management of Hamstring Injuries in Athletes: A Systematic Review.

BACKGROUND: It is important for clinicians to rely on suitable prognosis factors after hamstring injuries because of the high incidence of these injuries and time away from athletic activities. PURPOSE: To summarize the current literature on factors that influence return to play after a hamstring injury in athletes. STUDY DESIGN: Systematic review. METHODS: A computer-assisted literature search of CINAHL, MEDLINE, Embase, and EBM Reviews databases (and a manual search of the reference lists of all selected articles) was conducted using keywords related to hamstring injuries and return to play. The literature review criteria included (1) patients with an acute hamstring or posterior thigh injury; (2) a randomized controlled trial, cohort study, case-control study, case series, or prospective or retrospective design; (3) information on rehabilitation, physical therapy, clinical assessment, imaging techniques, and return to play; and (4) studies written in English or French. RESULTS: The search strategy identified 914 potential articles, of which 24 met the inclusion criteria. In terms of the clinical assessment, the following factors were associated with a longer recovery time: stretching-type injuries, recreational-level sports, structural versus functional injuries, greater range of motion deficit with the hip flexed at 90°, time to first consultation >1 week, increased pain on the visual analog scale, and >1 day to be able to walk pain free after the injury. As for magnetic resonance imaging studies, the following factors correlated with a longer recovery time: positive findings; higher grade of injury; muscle involvement >75%; complete transection; retraction; central tendon disruption of the biceps femoris; proximal tendon involvement; shorter distance to the ischial tuberosity; length of the hamstring injury; and depth, volume, and large cross-sectional area. With respect to ultrasound studies, the following factors were associated with a poor prognosis: large cross-sectional area, injury outside the musculotendinous junction, hematoma, structural injury, and injury involving the biceps femoris. Lastly, rehabilitation approaches that included hamstring loading during extensive lengthening or 4 daily sessions of static hamstring stretching led to shorter rehabilitation times. CONCLUSION: Numerous determinants have an effect on return to play after a hamstring injury in athletes. It is important for sports professionals to be aware of those determinants to guide athletes through the rehabilitation process and refine return-to-play strategies.