A return-to-sport algorithm for acute hamstring injuries

Abstract

Acute hamstring injuries are the most prevalent muscle injuries reported in sport. Despite a thorough and concentrated effort to prevent and rehabilitate hamstring injuries, injury occurrence and re-injury rates have not improved over the past 28 years. This failure is most likely due to the following: 1) an over-reliance on treating the symptoms of injury, such as subjective measures of “pain”, with drugs and interventions; 2) the risk factors investigated for hamstring injuries have not been related to the actual movements that cause hamstring injuries i.e. not functional; and, 3) a multi-factorial approach to assessment and treatment has not been utilized. The purpose of this clinical commentary is to introduce a model for progression through a return-to-sport rehabilitation following an acute hamstring injury. This model is developed from objective and quantifiable tests (i.e. clinical and functional tests) that are structured into a step-by-step algorithm. In addition, each step in the algorithm includes a treatment protocol. These protocols are meant to help the athlete to improve through each phase safely so that they can achieve the desired goals and progress through the algorithm and back to their chosen sport. We hope that this algorithm can serve as a foundation for future evidence based research and aid in the development of new objective and quantifiable testing methods.

Introduction

Hamstring muscle strains are the most prevalent muscle injuries reported in sport. Epidemiology studies have revealed that hamstring injuries alone account for between 6 and 29% of all injuries reported in Australian Rules football, rugby union, soccer, basketball, cricket and track sprinters (Brooks et al., 2005a, Brooks et al., 2005b, Croisier, 2004, Garrett, 1996, Meeuwisse et al., 2003, Orchard and Seward, 2002, Woods et al., 2004). In addition to the prevalence of hamstring injuries, frustration can be intensified by prolonged symptoms, poor healing responses and a high risk of re-injury at a rate of 12–31% (Croisier, 2004, Woods et al., 2004). Even more troubling is the fact that hamstring injury and re-injury rates have not improved over the last 28 years (Ekstrand & Gillquist, 1983, Hägglund et al., 2009). The constant re-injury rates are especially troubling as re-injuries are significantly more severe than initial injuries (Croisier, 2004; Werner et al., 2009; Woods et al., 2004). In addition, previous injury has constantly been found to be one of the greatest risk factors for future injury. These findings suggest that traditional hamstring prevention and rehabilitation programs have not been effective.

Traditionally, the criteria for an athlete to return-to-sport after an acute hamstring injury include a general post-injury timeline, isolated isokinetic strength testing, and subjective feedback from the patient and coaching/medical staff (Clanton and Coupe, 1998, Drezner, 2003, Heiderscheit et al., 2010, Hoskins and Pollard, 2005a, Hoskins and Pollard, 2005b; Hunter & Speed, 2007; Petersen and Holmich, 2005, Worrell, 1994). There are seven published studies on the treatment and management of acute hamstring injuries (Clanton and Coupe, 1998, Drezner, 2003, Heiderscheit et al., 2010, Hoskins and Pollard, 2005a, Hoskins and Pollard, 2005b; Hunter & Speed, 2007; Petersen and Holmich, 2005, Worrell, 1994). Each of these studies has identified three basic phases of rehabilitation: 1) the acute phase; 2) the sub-acute/rehabilitation phase; and, 3) the functional phase (see Table 1, Table 2). As can be seen in Table 1, the criteria for progressing to the second and third phases are determined by subjective measures and/or a post-injury timeline. However, clinicians should be aware of the potential gap between patients perceived and actual sport readiness. For example, in anterior cruciate ligament (ACL) injury studies, patient’s subjective scores did not significantly correlate with quantifiable strength and functional measures (Neeb et al., 1997, Ross et al., 2002). Only three of the seven studies mention an objective measure (i.e. isokinetic strength asymmetries) for progressing from the third phase back-to-sport (Drezner, 2003, Heiderscheit et al., 2010, Hoskins and Pollard, 2005a, Hoskins and Pollard, 2005b). However, it has been shown that concentric strength levels do not always decrease during isokinetic concentric testing and hamstring-to-quadriceps (H/Q) ratios are not affected after hamstring injuries (Bennell et al., 1998, Brockett et al., 2004, Worrell et al., 1991). Heiderscheit et al. (2010) is the most current and thorough of the hamstring management studies. Several detailed exercises are presented through a three phase progression (i.e. acute, regeneration and functional phase). However, this article also fails to provide any insight beyond subjective, ROM or isokinetic criteria for progressing an athlete back-to-sport.

We propose that a multi-factorial approach to rehabilitating hamstring injuries is needed, which includes reliable, objective and quantifiable criteria (clinical and functional) in order to determine how and when to progress a patient through each phase of a return-to-sport rehabilitation program. This algorithm is based on the various risk factors for hamstring injuries, and incorporates the current literature on biology of muscle injury and repair. The severity or injury shouldn’t affect the different phases of the algorithm, but would make it more difficult to achieve the criteria to advance through each phase. It should be noted that this algorithm has not yet been validated. However, each objective criterion in the model has shown to be reliable in the literature and clinical rationale is provided. We hope that this clinical commentary can inspire critical evaluation of the model (see Fig. 1), and lead to the development of further reliable, objective and quantitative measures encompassing a multi-factorial approach to rehabilitating acute hamstring injuries.