MRI appearance does not change in the first 7 days after acute hamstring injury—a prospective study

#ReadyToplay: hamstring injuries in women's football - a two-season prospective cohort study in the Norwegian women's premier league

In this two-season prospective cohort study (2020-2021), we aimed to describe the characteristics, clinical findings and magnetic resonance imaging (MRI) findings of hamstring injuries in the Norwegian women's premier league. Hamstring injuries were examined by team physiotherapists using a standardised clinical examination and injury form. Injury location and severity (modified Peetrons classification) were graded based on MRI by two independent radiologists. Fifty-three hamstring injuries were clinically examined, 31 of these with MRI. Hamstring injuries caused 8 days (median) lost from football (interquartile range: 3-15 days, range: 0-188 days), most were non-contact and occurred during sprinting. Gradual-onset (53%) and sudden-onset injuries (47%) were evenly distributed. The injuries examined with MRI were classified as grade 0 (52%), grade 1 (16%) or grade 2 (29%). One proximal tendinopathy case was not graded. Grade 2 injuries caused more time loss than grade 0 (19 ± 8 vs. 7 ± 7 days, p = 0.002). Of injuries with MRI changes, 60% were in the m. biceps femoris, mainly the muscle-tendon junction, and 40% in the m. semimembranosus, most in the proximal tendon. Compared to previous findings from men's football, a higher proportion of hamstring injuries in women's football had a gradual onset and involved the m. semimembranosus, particularly its proximal tendon.

Risk Factors for Rerupture After Proximal Hamstring Avulsion Injury Including the Optimal Timing for Surgery

BACKGROUND

Despite the prevalence of proximal hamstring avulsion injuries (PHAIs), the understanding of rerupture risk factors and the influence of injury chronicity on these rates remain limited.

PURPOSE

To investigate the rerupture rate after PHAI repair and identify its associated risk factors and the optimal time to primary surgery.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHOD

This is a retrospective analysis of prospectively collected data from the French Proximal Hamstring Avulsion Surgery Cohort Study targeting patients surgically treated for PHAI between 2002 and 2022. The primary outcome measure of this study was the rerupture rate of PHAI repair. The secondary outcome measures included the assessment of the potential risk factors for rerupture as well as the investigation of the incidence rate of rerupture for 100 person-years depending on various injury-surgery delay definitions.

RESULTS

This study analyzed 740 patients with a mean age of 45.9 years (SD, 13.6 years) and followed up for a mean of 4.9 years (SD, 3.9 years). The rerupture rate was 4.59% (34/740). Most reruptures (75%) occurred within the first 6 months after surgery (median, 88.5 days; interquartile range, 39.5-182 days), and 74% were atraumatic. Univariate analysis identified potential risk factors: longer initial surgery delay (hazard ratio [HR], 1.03; 95% CI, 1.01-1.04; P = .04) and initial complete ruptures (HR, 4.47; 95% CI, 1.07-18.7; P = .04). Receiver operating characteristic curve analysis found the optimal injury-surgery delay cutoff predicting rerupture to be 32 days (area under the curve, 0.62; 95% CI, 0.53-0.71). The relative Youden index was calculated at 0.24, corresponding to a sensitivity of 65% and a specificity of 59%. Surpassing this cutoff showed the highest HR (2.56), narrowest 95% CI (1.27-5.17), and highest incidence of rerupture (1.42 per 100 person-years) (P = .01). In the multivariate analysis, an injury-surgery delay of >32 days (HR, 2.5; 95% CI, 1.24-5.06; P = .01) and initial complete ruptures (HR, 4.33; 95% CI, 1.04-18.08; P = .04) emerged as significant risk factors for rerupture.

CONCLUSION

This study found a 4.59% rerupture risk after PHAI repair. Most reruptures (75%) occurred within the first 6 months after surgery. Risk factors for rerupture included chronicity and initial complete injury. The optimal threshold for chronicity of PHAI lesions, based on rerupture rate, was marked by an injury-surgery delay of >32 days.

Ultrasound shear wave seeds reduced following hamstring strain injury but not after returning to sport

OBJECTIVES

The purpose of the study was to investigate differences in ultrasound shear wave speed (SWS) between uninjured and injured limbs following hamstring strain injury (HSI) at time of injury (TOI), return to sport (RTS), and 12 weeks after RTS (12wks).

METHODS

This observational, prospective, cross-sectional design included male and female collegiate athletes who sustained an HSI. SWS imaging was performed at TOI, RTS, and 12wks with magnetic resonance imaging. SWS maps were acquired by a musculoskeletal-trained sonographer at the injury location of the injured limb and location-matched on the contralateral limb. The average SWS from three 5 mm diameter Q-boxes on each limb were used for analysis. A linear mixed effects model was performed to determine differences in SWS between limbs across the study time points.

RESULTS

SWS was lower in the injured limb compared to the contralateral limb at TOI (uninjured - injured limb difference: 0.23 [0.05, 0.41] m/s, p = 0.006). No between-limb differences in SWS were observed at RTS (0.15 [-0.05, 0.36] m/s, p = 0.23) or 12wks (-0.11 [-0.41, 0.18] m/s, p = 0.84).

CONCLUSIONS

The SWS in the injured limb of collegiate athletes after HSI was lower compared to the uninjured limb at TOI but not at RTS or 12 weeks after RTS.

CRITICAL RELEVANCE STATEMENT

Hamstring strain injury with structural disruption can be detected by lower injured limb shear wave speed compared to the uninjured limb. Lack of between-limb differences at return to sport may demonstrate changes consistent with healing. Shear wave speed may complement traditional ultrasound or MRI for monitoring muscle injury.

KEY POINTS

• Ultrasound shear wave speed can non-invasively measure tissue elasticity in muscle injury locations. • Injured limb time of injury shear wave speeds were lower versus uninjured limb but not thereafter. • Null return to sport shear wave speed differences may correspond to structural changes associated with healing. • Shear wave speed may provide quantitative measures for monitoring muscle elasticity during recovery.

MRI findings prior to return to play as predictors of reinjury in professional athletes: a novel decision-making tool

BACKGROUND

Because MRI has shown great accuracy in assessing acute muscle injuries, identification of risk factors for reinjury before return to play (RTP) in professional athletes during the healing process could be very relevant. We assessed the value of MRI findings prior to RTP as predictors of reinjury.

METHODS

Retrospective observational study of 59 professional athletes, mean age 26 years, with first-time acute muscle injury and successful rehabilitation ready to RTP. They underwent MRI within 6 days of the injury and within 7 days prior to RTP. The primary outcome was reinjury. Risk of reinjury was assessed using radiological signs in control MRI scans before RTP. The risk was classified as low, medium or high when none, one or two radiological signs were observed, respectively.

RESULTS

Reinjury occurred in 9 participants, with a rate of 15.2%. None of the baseline MRI-related variables was significantly associated with reinjury. In the control MRI scan performed within 7 days prior to RTP, three independent findings were significantly associated with reinjury. These included transversal and/or mixed connective tissue gap (p = 0.002), intermuscular oedema (p = 0.015) and callus gap (p = 0.046). In the predictive model of the risk of reinjury, the presence of two of these radiological signs, together with interstitial feathery oedema, was associated with a high risk of recurrence (OR 29.58, 95% CI 3.86-226.64; p = 0.001).

CONCLUSIONS

In professional athletes with acute muscle injuries of the lower limbs successfully rehabilitated, some radiological signs on MRI performed shortly before RTP were associated with a high risk of reinjury.

Location of Hamstring Injuries Based on Magnetic Resonance Imaging: A Systematic Review

CONTEXT

Hamstring muscle injury location using magnetic resonance imaging (MRI) is not so well described in the literature.

OBJECTIVE

To describe the location of hamstring injuries using MRI.

DATA SOURCES

PubMed, Web of Science, Scopus, SPORTDiscus, Cochrane Library.

STUDY SELECTION

The full text of studies, in English, had to be available. Case reports and reviews were excluded. Included studies must report the location of hamstring injuries using MRI within 8 days of the acute injury.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

A first screening was conducted based on title and abstract of the articles. In the second screening, the full text of the remaining articles was evaluated for the fulfillment of the inclusion criteria.

RESULTS

From the 2788 references initially found in 5 databases, we included 34 studies, reporting a total of 2761 acute hamstring injuries. The most frequent muscle head involved was the long head of the biceps femoris (BFLH) (70%), followed by the semitendinosus (ST) (15%), generally associated with BFLH. The most frequent tissue affected was the myotendinous junction (MTJ) accounting for half the cases (52%). Among all lesions, the distribution between proximal, central, and distal lesions looked homogenous, with 34.0%, 33.4% and 32.6%, respectively. The stretching mechanism, while only reported in 2 articles, represented 3% of all reported mechanisms, appears responsible for a specific lesion involving the proximal tendon of the semimembranosus (SM), and leading to a longer time out from sport.

CONCLUSION

BFLH was the most often affected hamstring injuries and MTJ was the most affected tissue. In addition, the distal, central, and proximal locations were homogeneously distributed. We also noted that MRI descriptions of hamstring injuries are often poor and did not take full advantage of the MRI strengths.

SYSTEMATIC REVIEW REGISTRATION

Before study initiation, the study was registered in the PROSPERO International prospective register of systematic reviews (registration number CRD42018107580).

Spatial frequency analysis detects altered tissue organization following hamstring strain injury at time of injury but not return to sport

Background

Hamstring strain injury (HSI) diagnosis is often corroborated using ultrasound. Spatial frequency analysis (SFA) is a quantitative ultrasound method that has proven useful in characterizing altered tissue organization. The purpose of this study was to determine changes in muscular tissue organization using SFA following HSI.

Methods

Ultrasound B-mode images were captured at time of injury (TOI) and return to sport (RTS) in collegiate athletes who sustained an HSI. Spatial frequency parameters extracted from two-dimensional Fourier Transforms in user-defined regions of interest (ROI) were analyzed. Separate ROIs encompassed injured and adjacent tissue within the same image of the injured limb and mirrored locations in the contralateral limb at TOI. The ROIs for RTS images were drawn to correspond to the injury-matched location determined from TOI imaging. Peak spatial frequency radius (PSFR) and the fascicular banded pattern relative to image background (Mmax%) were compared between injured and adjacent portions within the same image with separate paired t-tests. Within-image differences of SFA parameters in the injured limb were calculated and compared between TOI and RTS with Wilcoxon rank sum tests.

Results

Within the injured limb at TOI, PSFR differences in injured and healthy regions did not strictly meet statistical significance (p = 0.06), while Mmax% was different between regions (p < 0.001). No differences were observed between regions in the contralateral limb at TOI (PSFR, p = 0.16; Mmax%, p = 0.30). Significant within-image differences in PSFR (p = 0.03) and Mmax% (p = 0.04) at RTS were detected relative to TOI.

Conclusions

These findings are a first step in determining the usefulness of SFA in muscle injury characterization and provide quantitative assessment of both fascicular disruption and edema presence in acute HSI.

[Analysis of muscle injuries and return-to-training in elite Taekwondo athletes: results of a prospective cohort study over a period of five years]

BACKGROUND

 Muscle injuries frequently occur in sports involving explosive movement patterns, and they can cause considerable downtime. There is a lack of detailed data on muscle injuries in Olympic elite Taekwondo.

METHODS

 All injuries sustained by 76 elite Taekwondo athletes from a national Olympic training centre during training and competition were prospectively recorded over a period of five years. Data on muscle injuries, including location and time elapsed until return-to-training, were extracted from medical records. Injuries were diagnosed by means of MRI and were classified according to the British Athletes Muscle Injury System. The relationship between MRI classification subgroups and time elapsed until return-to-training was assessed.

RESULTS

 Mean age of athletes was 22.5 ± 3.2 (16-27) years with an average Taekwondo experience of 12.1 ± 4.0 (7-20) years. Hamstring muscles were most commonly injured (48.4 %), followed by quadriceps muscles (32.3 %) and calf muscles (9.6 %). The analysis of MRI injury subgroups showed grade 1 (32.2 %) and grade 2 (41.9 %) injuries in most cases. A positive correlation was found between injury groups and return-to-training (r = 0.56). The comparison between different injury groups and time elapsed until return-to-training also revealed significant differences (p < 0.0001).

CONCLUSION

 Hamstring muscles are the most injured muscles in Taekwondo besides the quadriceps femoris muscle. Most injuries were mild to moderate (grade 1-2). The time needed for return-to-training increased significantly with the severity of injuries diagnosed by MRI.

Associations between clinical findings and MRI injury extent in male athletes with acute adductor injuries - A cross-sectional study

OBJECTIVES

To investigate the association between clinical assessment and MRI measures of oedema and MRI grading in male athletes with acute adductor injuries.

DESIGN

Cross-sectional study.

METHODS

We included 81 consecutive athletes with acute adductor injuries. All athletes received a standardized clinical assessment and magnetic resonance imaging (MRI), blinded to clinical information. We analysed correlations between extent of palpation pain and extent of MRI oedema for the adductor longus. We compared the clinical assessment to MRI adductor injury grading (0-3) using ordinal regression. We analysed positive and negative predictive values (PPV/NPV) of a complete adductor longus avulsion.

RESULTS

Proximal-distal length of adductor longus palpation pain had fair correlation with MRI proximal-distal oedema length oedema (r=0.309, p=0.022). Cross-sectional surface area of palpation pain had poor correlation with corresponding cross-sectional MRI oedema area (r=0.173, p=0.208). The symptoms subscale of the Copenhagen Hip And Groin Outcome Score (HAGOS) for the period since injury (log odds ratio=0.97, p=0.021) and passive adductor stretch pain (log odds ratio=0.35, p=0.046) were associated with MRI injury grading. If there was a palpable defect, MRI always showed a complete avulsion (PPV=100%). Several tests had high negative predictive values: passive adductor stretch (100%), palpation pain at the adductor longus insertion (98%), and the FABER test (98%).

CONCLUSIONS

The extent of palpation pain does not indicate the extent of MRI oedema in acute adductor longus injuries. A worse modified HAGOS symptoms subscale score and passive adductor stretch pain indicate a higher MRI adductor injury grade. Clinical examination tests have high ability to detect or rule out a complete adductor longus avulsion on MRI.

Improvements in Match-Related Physical Performance of Professional Soccer Players After the Application of an on-Field Training Program for Hamstring Injury Rehabilitation

CONTEXT

Although there are multiple, validated return-to-play programs following hamstring strain injuries, no studies have evaluated their changes in match performance parameters.

OBJECTIVES

The aim of this study was twofold as follows: (1) to determine the changes in match-based physical performance parameters in professional soccer players before and after sustaining a hamstring strain injury and undergoing a soccer-specific rehabilitation program and (2) to observe the progress of these performance parameters 6 to 10 weeks after the player returned from injury.

DESIGN

Prospective, quasi-experimental longitudinal study.

SETTING

Soccer playing and training grounds.

PARTICIPANTS

Nineteen players suffering a hamstring strain injury from 2 male professional teams playing in the Spanish professional football league (La Liga) were followed during the 2015-2016, 2016-2017, and 2017-2018 seasons.

INTERVENTION

Participation in on-field training program following a hamstring injury.

MAIN OUTCOME MEASURES

Match global positioning system data were collected in the following stages: prior to injury (PRE), after return to play (RTP), program, and 6 to 10 weeks following RTP (C2). Peak velocities and distances ran at sprint velocities showed most likely improvements in C2 versus PRE, and very likely improvements in RTP versus PRE.

RESULTS

The distances ran at high and very high intensities, the average velocity, and work-to-rest ratio showed very likely improvements in C2 versus RTP and likely improvements in RTP versus PRE. Likely improvements were observed for all variables in C2 versus RTP. The authors' results showed an improvement of physical performance during competitive match after RTP, compared with PRE. There was a steady progression in the progress, and in 8 months following RTP, there was no injury reported in the players.

CONCLUSIONS

The current findings may indicate that the hamstring muscle complex not only recovered completely from the injury but could also withstand a greater training and match load reducing the risk of reinjury.

Sports-related lower limb muscle injuries: pattern recognition approach and MRI review

Muscle injuries of the lower limbs are currently the most common sport-related injuries, the impact of which is particularly significant in elite athletes. MRI is the imaging modality of choice in assessing acute muscle injuries and radiologists play a key role in the current scenario of multidisciplinary health care teams involved in the care of elite athletes with muscle injuries. Despite the frequency and clinical relevance of muscle injuries, there is still a lack of uniformity in the description, diagnosis, and classification of lesions. The characteristics of the connective tissues (distribution and thickness) differ among muscles, being of high variability in the lower limb. This variability is of great clinical importance in determining the prognosis of muscle injuries. Recently, three classification systems, the Munich consensus statement, the British Athletics Muscle Injury classification, and the FC Barcelona-Aspetar-Duke classification, have been proposed to assess the severity of muscle injuries. A protocolized approach to the evaluation of MRI findings is essential to accurately assess the severity of acute lesions and to evaluate the progression of reparative changes. Certain MRI findings which are seen during recovery may suggest muscle overload or adaptative changes and appear to be clinically useful for sport physicians and physiotherapists.

Associations Between Initial Clinical Examination and Imaging Findings and Return-to-Sport in Male Athletes With Acute Adductor Injuries: A Prospective Cohort Study

BACKGROUND

Time to return-to-sport (RTS) after acute adductor injuries varies among athletes, yet we know little about which factors determine this variance.

PURPOSE

To investigate the association between initial clinical and imaging examination findings and time to RTS in male athletes with acute adductor injuries.

STUDY DESIGN

Cohort study (Prognosis); Level of evidence, 2.

METHODS

Male adult athletes with an acute adductor injury were included within 7 days of injury. Standardized patient history and clinical and magnetic resonance imaging (MRI) examinations were conducted for all athletes. Athletes performed a supervised standardized criteria-based exercise treatment program. Three RTS milestones were defined: (1) clinically pain-free, (2) completed controlled sports training, and (3) first full team training. Univariate and multiple regression analyses were performed to determine the association between the specific candidate variables of the initial examinations and the RTS milestones.

RESULTS

We included 81 male adult athletes. The median duration for the 3 RTS milestones were 15 days (interquartile range, 12-28 days), 24 days (16-32 days), and 22 days (15-31 days), respectively. Clinical examination including patient history was able to explain 63%, 74%, and 68% of the variance in time to RTS. The strongest predictors for longer time to RTS were pain on palpation of the proximal adductor longus insertion or a palpable defect. The addition of MRI increased the explained variance with 7%, 0%, and 7%. The strongest MRI predictor was injury at the bone-tendon junction. Post hoc multiple regression analyses of players without the 2 most important clinical findings were able to explain 24% to 31% of the variance, with no added value of the MRI findings.

CONCLUSION

The strongest predictors of a longer time to RTS after acute adductor injury were palpation pain at the proximal adductor longus insertion, a palpable defect, and/or an injury at the bone-tendon junction on MRI. For athletes without any of these findings, even extensive clinical and MRI examination does not assist considerably in providing a more precise estimate of time to RTS.

Italian consensus conference on guidelines for conservative treatment on lower limb muscle injuries in athlete

Provide the state of the art concerning (1) biology and aetiology, (2) classification, (3) clinical assessment and (4) conservative treatment of lower limb muscle injuries (MI) in athletes. Seventy international experts with different medical backgrounds participated in the consensus conference. They discussed and approved a consensus composed of four sections which are presented in these documents. This paper represents a synthesis of the consensus conference, the following four sections are discussed: (i) The biology and aetiology of MIs. A definition of MI was formulated and some key points concerning physiology and pathogenesis of MIs were discussed. (ii) The MI classification. A classification of MIs was proposed. (iii) The MI clinical assessment, in which were discussed anamnesis, inspection and clinical examination and are provided the relative guidelines. (iv) The MI conservative treatment, in which are provided the guidelines for conservative treatment based on the severity of the lesion. Furthermore, instrumental therapy and pharmacological treatment were discussed. Knowledge of the aetiology and biology of MIs is an essential prerequisite in order to plan and conduct a rehabilitation plan. Another important aspect is the use of a rational MI classification on prognostic values. We propose a classification based on radiological investigations performed by ultrasonography and MRI strongly linked to prognostic factors. Furthermore, the consensus conference results will able to provide fundamental guidelines for diagnostic and rehabilitation practice, also considering instrumental therapy and pharmacological treatment of MI. Expert opinion, level IV.

Magnetic resonance imaging for assessing hamstring injuries: clinical benefits and pitfalls - a review of the current literature

Hamstring injuries are common injuries in all levels of athletics. Hamstring injuries can cause prolonged absence from sports and have a notorious rate of reinjury. Magnetic resonance imaging (MRI) is being increasingly utilized following a hamstring injury. Physicians are being increasingly asked to utilize MRI to predict clinical outcomes, including time frame for return to play and risk of reinjury. In spite of numerous studies in this area, no clear consensus exists. The purpose of this paper is to summarize the literature and evidence regarding the role of MRI in treating hamstring injuries.