The effects of early mobilisation and immobilisation on the healing process following muscle injuries

Muscle injuries in athletes: enhancing recovery through scientific understanding and novel therapies

Context:

Muscle injuries are extremely common in athletes and often produce pain, dysfunction, and the inability to return to practice or competition. Appropriate diagnosis and management can optimize recovery and minimize time to return to play.

Evidence Acquisition:

Contemporary papers, both basic science and clinical medicine, that investigate muscle healing were reviewed. A Medline/PubMed search inclusive of years 1948 to 2012 was performed.

Results:

Diagnosis can usually be made according to history and physical examination for most injuries. Although data are limited, initial conservative management emphasizing the RICE principles and immobilization of the extremity for several days for higher grade injuries are typically all that is required. Injection of corticosteroids may clinically enhance function after an acute muscle strain. Additional adjunctive treatments (nonsteroidal anti-inflammatory drugs, platelet-rich plasma, and others) to enhance muscle healing and limit scar formation show promise but need additional data to better define their roles.

Conclusion:

Conservative treatment recommendations will typically lead to successful outcomes after a muscle injury. There is limited evidence to support most adjunctive treatments.

Increased serum and musculotendinous fibrogenic proteins following persistent low-grade inflammation in a rat model of long-term upper extremity overuse

We examined the relationship between grip strength declines and muscle-tendon responses induced by long-term performance of a high-repetition, low-force (HRLF) reaching task in rats. We hypothesized that grip strength declines would correlate with inflammation, fibrosis and degradation in flexor digitorum muscles and tendons. Grip strength declined after training, and further in weeks 18 and 24, in reach limbs of HRLF rats. Flexor digitorum tissues of reach limbs showed low-grade increases in inflammatory cytokines: IL-1β after training and in week 18, IL-1α in week 18, TNF-α and IL-6 after training and in week 24, and IL-10 in week 24, with greater increases in tendons than muscles. Similar cytokine increases were detected in serum with HRLF: IL-1α and IL-10 in week 18, and TNF-α and IL-6 in week 24. Grip strength correlated inversely with IL-6 in muscles, tendons and serum, and TNF-α in muscles and serum. Four fibrogenic proteins, TGFB1, CTGF, PDGFab and PDGFbb, and hydroxyproline, a marker of collagen synthesis, increased in serum in HRLF weeks 18 or 24, concomitant with epitendon thickening, increased muscle and tendon TGFB1 and CTGF. A collagenolytic gelatinase, MMP2, increased by week 18 in serum, tendons and muscles of HRLF rats. Grip strength correlated inversely with TGFB1 in muscles, tendons and serum; with CTGF-immunoreactive fibroblasts in tendons; and with MMP2 in tendons and serum. Thus, motor declines correlated with low-grade systemic and musculotendinous inflammation throughout task performance, and increased fibrogenic and degradative proteins with prolonged task performance. Serum TNF-α, IL-6, TGFB1, CTGF and MMP2 may serve as serum biomarkers of work-related musculoskeletal disorders, although further studies in humans are needed.

Experimental model for the study of the effects of platelet-rich plasma on the early phases of muscle healing

BACKGROUND

There is abundant evidence suggesting that growth factors may play a key role in the healing process, especially in the early stages of inflammation. Despite the reported clinical successes with the use of growth factors there is still a lack of knowledge on the biological mechanism underlying the activity of platelet-rich plasma during the process of muscle healing. The aim of this study was to analyse the early effects of platelet- rich plasma in an easily reproducible animal model.

MATERIALS AND METHODS

Wistar male adult rats (n=102) were used in this study. The muscle lesion was created with a scalpel in the flexor sublimis muscles. Platelet-rich plasma was applied immediately after surgery. Treated, untreated and contralateral muscles were analysed by morphological evaluation and western blot assay.

RESULTS

Leucocyte infiltration was significantly greater in muscles treated with platelet-rich plasma than in both untreated and contralateral muscles. The latter showed greater leucocyte infiltration when compared to the untreated muscles. Platelet-rich plasma treatment also modified the cellular composition of the leucocyte infiltration leading to increased expression of CD3, CD8, CD19 and CD68 and to decreased CD4 antigen expression in both platelet-rich plasma treated and contralateral muscles. Blood vessel density and blood vessel diameters were not statistically significantly different between the three groups analysed.

DISCUSSION

The results of this study showed that treatment with platelet-rich plasma magnified the physiological early inflammatory response following a muscle injury, modifying the pattern of cellular recruitment. Local platelet-rich plasma treatment may exert a direct or, more plausibly, indirect systemic effect on healing processes, at least in the earliest inflammatory phase.

[Current treatment concepts for muscular injuries]

Muscular lesions represent the most common form of sports injury. The four large muscle groups hamstrings, adductors, gastrocnemius and knee extensor muscles are most often affected. Most injuries occur during excentric tension impact. Diagnostics begin with an exact medical history and detailed clinical investigations. Imaging with ultrasound and magnetic resonance imaging (MRI) are important to differentiate between structural lesions and functional disorders and to determine the extent of the injury. Most frequently treatment remains conservative and is oriented to the three phases of the healing process. In most cases (leisure sports) the rest, ice, compression and elevation (RICE) concept with subsequent pain-adapted load increase suffices for a return to sport activities. Infiltration therapy including platelet-rich plasma (PRP) is an additional therapy option but should not be used to accelerate the healing process. Surgical treatment only rarely becomes necessary for treatment of muscular injuries.

Acute muscle strain injuries: a proposed new classification system

PURPOSE

To better define and classify acute muscle strain injuries.

METHODS

Historically, acute muscle strains have been classified as grade I, II and III. This system does not accurately reflect the anatomy of the injury and has not been shown to reliably predict prognosis and time for return to sport.

RESULTS

We describe an imaging (magnetic resonance or ultrasound) nomenclature, which considers the anatomical site, pattern and severity of the lesion in the acute stage. By site of injury, we define muscular injuries as proximal, middle and distal. Anatomically, based on the various muscular structures involved, we distinguish intramuscular, myofascial, myofascial/perifascial and musculotendinous injuries.

CONCLUSIONS

This classification system must be applied to a variety of muscle architectures and locations to determine its utility; additional studies are therefore needed prior to its general acceptance.

LEVEL OF EVIDENCE

V.

Outcome of Grade I and II Hamstring Injuries in Intercollegiate Athletes: A Novel Rehabilitation Protocol

Background:

Hamstring muscle strains represent a common and disabling athletic injury with variable recurrence rates and prolonged recovery times.

Objectives:

To present the outcomes of a novel rehabilitation protocol for the treatment of proximal hamstring strains in an intercollegiate sporting population and to determine any significant differences in the rate of reinjury and time to return to sport based on patient and injury characteristics.

Study Design:

Retrospective case series.

Methods:

A retrospective review was performed of 48 consecutive hamstring strains in intercollegiate athletes. The rehabilitation protocol consisted of early mobilization, with flexible progression through supervised drills. Athletes were allowed to return to sport after return of symmetrical strength and range of motion with no pain during sprinting. Primary outcomes included time to return to sport and reinjury rates.

Results:

All patients returned to their sports, and 3 sustained repeat hamstring strains (6.2% reinjury rate) after a minimum follow-up of 6 months. The average number of days missed from sport was 11.9 (range, 5-23 days). There was no statistically significant difference for time to return to sport between first-time and recurrent injuries and between first- and second-degree injuries (P > 0.05).

Conclusions:

Grade I and II hamstring strains may be aggressively treated with a protocol of brief immobilization followed by early initiation of running and isokinetic exercises—with an average expected return to sport of approximately 2 weeks and with a relatively low reinjury rate regardless of injury grade (I or II), injury characteristics (including first-time and recurrent injuries), or athlete characteristics.

Biological approaches to improve skeletal muscle healing after injury and disease

Skeletal muscle injury and repair are complex processes, including well-coordinated steps of degeneration, inflammation, regeneration, and fibrosis. We have reviewed the recent literature including studies by our group that describe how to modulate the processes of skeletal muscle repair and regeneration. Antiinflammatory drugs that target cyclooxygenase-2 were found to hamper the skeletal muscle repair process. Muscle regeneration phase can be aided by growth factors, including insulin-like growth factor-1 and nerve growth factor, but these factors are typically short-lived, and thus more effective methods of delivery are needed. Skeletal muscle damage caused by traumatic injury or genetic diseases can benefit from cell therapy; however, the majority of transplanted muscle cells (myoblasts) are unable to survive the immune response and hypoxic conditions. Our group has isolated neonatal skeletal muscle derived stem cells (MDSCs) that appear to repair muscle tissue in a more effective manner than myoblasts, most likely due to their better resistance to oxidative stress. Enhancing antioxidant levels of MDSCs led to improved regenerative potential. It is becoming increasingly clear that stem cells tissue repair by direct differentiation and paracrine effects leading to neovascularization of injured site and chemoattraction of host cells. The factors invoked in paracrine action are still under investigation. Our group has found that angiotensin II receptor blocker (losartan) significantly reduces fibrotic tissue formation and improves repair of murine injured muscle. Based on these data, we have conducted a case study on two hamstring injury patients and found that losartan treatment was well tolerated and possibly improved recovery time. We believe this medication holds great promise to optimize muscle repair in humans.

[Muscle injuries: diagnostics and treatments]

Muscle injuries are common in sports. They are usually caused by either acute (mostly eccentric mechanisms) or chronic overloading with a lack of muscle coordination. They present in clinical practice as bruises and muscle sprains. Due to the rigours of a modern society and the high economic cost of time off work, an effective treatment needs to be employed. The key to an optimised therapy rests in the appropriate timing between immobilisation and mobilisation. The interval to muscle repair might be shortened by certain adjuvant therapies. In doing so, it is important that no physiological phases of wound healing are overlooked. Muscle healing can be accelerated by externally induced higher metabolic turnover. Surgical therapy is sometimes necessary in selected cases and in serious injuries.

A return-to-sport algorithm for acute hamstring injuries

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.

Muscle healing and nerve regeneration in a muscle contusion model in the rat

The nervous system is known to be involved in inflammation and repair. We aimed to determine the effect of physical activity on the healing of a muscle injury and to examine the pattern of innervation. Using a drop-ball technique, a contusion was produced in the gastrocnemius in 20 rats. In ten the limb was immobilised in a plaster cast and the remaining ten had mobilisation on a running wheel. The muscle and the corresponding dorsal-root ganglia were studied by histological and immunohistochemical methods. In the mobilisation group, there was a significant reduction in lymphocytes (p = 0.016), macrophages (p = 0.008) and myotubules (p = 0.008) between three and 21 days. The formation of myotubules and the density of nerve fibres was significantly higher (both p = 0.016) compared with those in the immobilisation group at three days, while the density of CGRP-positive fibres was significantly lower (p = 0.016) after 21 days. Mobilisation after contusional injury to the muscle resulted in early and increased formation of myotubules, early nerve regeneration and progressive reduction in inflammation, suggesting that it promoted a better healing response.

Hamstring strain injuries: recommendations for diagnosis, rehabilitation, and injury prevention

Hamstring strain injuries remain a challenge for both athletes and clinicians, given their high incidence rate, slow healing, and persistent symptoms. Moreover, nearly one third of these injuries recur within the first year following a return to sport, with subsequent injuries often being more severe than the original. This high reinjury rate suggests that commonly utilized rehabilitation programs may be inadequate at resolving possible muscular weakness, reduced tissue extensibility, and/or altered movement patterns associated with the injury. Further, the traditional criteria used to determine the readiness of the athlete to return to sport may be insensitive to these persistent deficits, resulting in a premature return. There is mounting evidence that the risk of reinjury can be minimized by utilizing rehabilitation strategies that incorporate neuromuscular control exercises and eccentric strength training, combined with objective measures to assess musculotendon recovery and readiness to return to sport. In this paper, we first describe the diagnostic examination of an acute hamstring strain injury, including discussion of the value of determining injury location in estimating the duration of the convalescent period. Based on the current available evidence, we then propose a clinical guide for the rehabilitation of acute hamstring injuries, including specific criteria for treatment progression and return to sport. Finally, we describe directions for future research, including injury-specific rehabilitation programs, objective measures to assess reinjury risk, and strategies to prevent injury occurrence.

LEVEL OF EVIDENCE

Diagnosis/therapy/prevention, level 5.

Stem cells for the treatment of skeletal muscle injury

Skeletal muscle injuries are extremely common, accounting for up to 35%-55% of all sports injuries and quite possibly affecting all musculoskeletal traumas. These injuries result in the formation of fibrosis, which may lead to the development of painful contractures, increases patients' risk for repeat injuries, and limits their ability to return to a baseline or pre-injury level of function. The development of successful therapies for these injuries must consider the pathophysiology of these musculoskeletal conditions. We discuss the direct use of muscle-derived stem cells and some key cell population dynamics as well as the use of clinically applicable modalities that may enhance the local supply of stem cells to the zone of injury by promoting angiogenesis.

Avaliação das propriedades mecânicas do músculo gastrocnêmio de ratas imobilizado e submetido à corrente russa

A eletroestimulação neuromuscular por corrente russa, recurso utilizado na reabilitação, pode aumentar o trofismo e restabelecer a força muscular, sobretudo dos músculos que apresentam deficit pós-imobilização, como é o caso de lesões durante a prática esportiva. Objetivou-se avaliar as propriedades mecânicas do músculo gastrocnêmio de ratas imobilizadas por 14 dias e posteriormente submetidas à eletroestimulação por corrente russa durante 10 dias. Utilizaram-se 32 ratas Wistar divididas em quatro grupos: controle (G1), imobilizado (G2); imobilizado e liberado por 10 dias (G3) e imobilizado e submetido à corrente russa por 10 dias (G4). A avaliação das propriedades mecânicas - carga, alongamento, rigidez e resiliência - foi feita por ensaio de tração longitudinal. Quanto à carga no limite máximo, o G4 apresentou valores mais elevados quando comparado ao grupo apenas imobilizado (G2, p<0,001), embora sem atingir o valor do G1. Na análise da propriedade de alongamento no limite máximo, G3 e G4 alcançaram valores significativamente maiores que o G2 (p<0,001). No que se refere à rigidez, apenas G2 alcançou valores maiores (p<0,05) que o G1. Quanto à resiliência, G4 apresentou valores inferiores ao grupo controle (p<0,05), mas ainda superiores aos do G2 (p<0,001). Portanto conclui-se que a corrente russa, quando aplicada por 10 dias após 14 dias de imobilização, é benéfica, embora não seja capaz de restabelecer todas as propriedades mecânicas do músculo em nível controle.

Improved muscle healing after contusion injury by the inhibitory effect of suramin on myostatin, a negative regulator of muscle growth

BACKGROUND

Muscle contusions are the most common muscle injuries in sports medicine. Although these injuries are capable of healing, incomplete functional recovery often occurs.

HYPOTHESIS

Suramin enhances muscle healing by both stimulating muscle regeneration and preventing fibrosis in contused skeletal muscle.

STUDY DESIGN

Controlled laboratory study.

METHODS

In vitro: Myoblasts (C2C12 cells) and muscle-derived stem cells (MDSCs) were cultured with suramin, and the potential of suramin to induce their differentiation was evaluated. Furthermore, MDSCs were cocultured with suramin and myostatin (MSTN) to monitor the capability of suramin to neutralize the effect of MSTN. In vivo: Varying concentrations of suramin were injected in the tibialis anterior muscle of mice 2 weeks after muscle contusion injury. Muscle regeneration and scar tissue formation were evaluated by histologic analysis and functional recovery was measured by physiologic testing

RESULTS

In vitro: Suramin stimulated the differentiation of myoblasts and MDSCs in a dose-dependent manner. Moreover, suramin neutralized the inhibitory effect of MSTN on MDSC differentiation. In vivo: Suramin treatment significantly promoted muscle regeneration, decreased fibrosis formation, reduced myostatin expression in injured muscle, and increased muscle strength after contusion injury.

CONCLUSION

Intramuscular injection of suramin after a contusion injury improved overall skeletal muscle healing. Suramin enhanced myoblast and MDSC differentiation and neutralized MSTN's negative effect on myogenic differentiation in vitro, which suggests a possible mechanism for the beneficial effects that this pharmacologic agent exhibits in vivo.

CLINICAL RELEVANCE

These findings could contribute to the development of biological treatments to aid in muscle healing after experiencing a muscle injury.

Angiotensin II receptor blockade administered after injury improves muscle regeneration and decreases fibrosis in normal skeletal muscle

BACKGROUND

Several therapeutic agents have been shown to inhibit fibrosis and improve regeneration after injury in skeletal muscle by antagonizing transforming growth factor-beta1. Angiotensin receptor blockers have been shown to have a similar effect on transforming growth factor-beta1 in a variety of tissues.

HYPOTHESIS

Systemic treatment of animals after injury of skeletal muscle with an angiotensin receptor blocker may decrease fibrosis and improve regeneration, mainly through transforming growth factor-beta1 blockade, and can be used to improve skeletal muscle healing after injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

Forty mice underwent bilateral partial gastrocnemius lacerations. Mice were assigned randomly to a control group (tap water), a low-dose angiotensin receptor blocker group (losartan, 0.05 mg/mL), or a high-dose angiotensin receptor blocker group (0.5 mg/mL). The medication was dissolved in tap water and administered enterally. Mice were sacrificed 3 or 5 weeks after injury, and the lacerated muscles were examined histologically for muscle regeneration and fibrosis.

RESULTS

Compared with control mice at 3 and 5 weeks, angiotensin receptor blocker-treated mice exhibited a histologic dose-dependent improvement in muscle regeneration and a measurable reduction in fibrous tissue formation within the area of injury.

CONCLUSION

By modulating the response to local and systemic angiotensin II, angiotensin receptor blocker therapy significantly reduced fibrosis and led to an increase in the number of regenerating myofibers in acutely injured skeletal muscle. The clinical implications for this application of angiotensin receptor blockers are potentially far-reaching and include not only sports- and military-related injuries, but also diseases such as the muscular dystrophies and trauma- and surgery-related injury.

CLINICAL RELEVANCE

Angiotensin receptor blockers may provide a safe, clinically available treatment for improving healing after skeletal muscle injury.

When should a cervical collar be used to treat neck pain?

Neck pain is one of the most prevalent and costly health problems in the United States. It remains a complex, subjective experience with a variety of musculoskeletal causes. Although, cervical collars are a seemingly benign intervention, they can have adverse effects, especially when used for longer periods of time. It is feared that a long period of immobilization, can result in atrophy-related secondary damage. Many physicians cite anecdotal evidence of their clinical utility and soft cervical collars are often prescribed by convention for patients complaining of neck pain. The use of cervical collars to treat neck pain is an area of controversy. This review article examines the current evidence and studies related to recommending cervical collars for neck pain of a variety of etiologies.

Initial intramuscular perfusion pressure predicts early skeletal muscle function following isolated tibial fractures

BACKGROUND

The severity of associated soft tissue trauma in complex injuries of the extremities guides fracture treatment and decisively determines patient's prognosis. Trauma-induced microvascular dysfunction and increased tissue pressure is known to trigger secondary soft tissue damage and seems to adversely affect skeletal muscle function.

METHODS

20 patients with isolated tibial fractures were included. Blood pressure and compartment pressure (anterior and deep posterior compartment) were measured continuously up to 24 hours. Corresponding perfusion pressure was calculated. After 4 and 12 weeks isokinetic muscle peak torque and mean power of the ankle joint in dorsal and plantar flexion were measured using a Biodex dynamometer.

RESULTS

A significant inverse correlation between the anterior perfusion pressure at 24 hours and deficit in dorsiflexion at 4 weeks was found for both, the peak torque (R = -0.83; p < 0.01) and the mean power (R = -0.84; p < 0.01). The posterior perfusion pressure at 24 h and the plantar flexion after 4 weeks in both, peak torque (R = -0.73, p = or < 0.05) and mean power (R = -0.7, p = or < 0.05) displayed a significant correlation.

CONCLUSION

The functional relationship between the decrease in intramuscular perfusion pressures and muscle performance in the early rehabilitation period indicate a causative and prognostic role of early posttraumatic microcirculatory derangements and skeletal muscle function. Therapeutic concepts aimed at effective muscle recovery, early rehabilitation, and decreased secondary tissue damage, should consider the maintenance of an adequate intramuscular perfusion pressure.

Estimulação elétrica neuromuscular e o alongamento passivo manual na recuperação das propriedades mecânicas do músculo gastrocnêmio imobilizado

Avaliamos a influência da imobilização, remobilização livre, remobilização com alongamento passivo manual, remobilização com estimulação elétrica neuromuscular (NMES) e remobilização por NMES e alongamento passivo manual associados sobre algumas propriedades mecânicas do músculo gastrocnêmio de ratas. Foram avaliadas 60 ratas divididas em seis grupos.Um destes grupos foi usado como controle. Todos os outros grupos tiveram o membro posterior direito imobilizado por 14 dias consecutivos. Destes grupos um foi imobilizado e em seguida avaliado, um foi liberado da imobilização e permaneceu nas gaiolas plásticas por 10 dias, outro foi submetido a técnica de alongamento passivo manual por 10 dias consecutivos, outro foi submetido a NMES por 10 dias consecutivos e o último foi submetido a NMES somado ao alongamento passivo manual por 10 dias consecutivos. Observamos que a imobilização reduziu os valores das propriedades mecânicas avaliadas no músculo. A remobilização livre não restabeleceu nenhuma das propriedades avaliadas. A remobilização por alongamento passivo manual devolveu ao músculo as propriedades de alongamento no limite de proporcionalidade, rigidez e resiliência. A remobilização estimulada por NMES restabeleceu todas as propriedades estudadas. A remobilização por NMES somada ao alongamento passivo restabeleceu as propriedades mecânicas de alongamento no limite máximo e de proporcionalidade e rigidez.

A modified surgical method for treating Baker's cyst in children

Surgery for Baker's cysts in children is plagued by high recurrent rate after the operation. In this study, a modified surgical method is developed to avoid the recurrence. Between 1995 and 2002, nine symptomatic Baker's cysts were excised in nine children, including six boys and three girls with a mean age of 5.7 years, were reviewed retrospectively. The diagnosis and follow-up were confirmed by clinical and ultrasound investigation. The modified surgical technique features a step in which the orifice of the posterior joint capsule is closed tightly by the application of one purse-string non-absorbable suture, and augmented by the suturing of the gastronomies tendon onto the closed orifice of the knee-joint capsule. Then the affected knee is immobilized with long leg cast for 2 weeks. After a mean follow-up of 8.3 years (ranged from 5.6 years to 12.1 years), none of the cysts recurred. All the patients were free of symptoms and none complained of any cosmetic problems. While comparing the affected and the unaffected knee, neither limitation of motion nor difference of muscle power was found. From the results, the modified surgical method is considered effective to treat the symptomatic Baker's cyst in children and to avoid its recurrence.

Muscle injuries: optimising recovery

Muscle injuries are one of the most common traumas occurring in sports. Despite their clinical importance, there are only a few clinical studies on the treatment of muscle injuries. Lack of clinical studies is most probably attributable to the fact that there is not only a high heterogeneity in the severity of injuries, but also the injuries take place in different muscles, making it very demanding to carry out clinical trials. Accordingly, the current treatment principles of muscle injuries have either been derived from experimental studies or been tested empirically only. Clinically, first aid for muscle injuries follows the RICE (Rest, Ice, Compression and Elevation) principle. The objective of RICE is to stop the injury-induced bleeding into the muscle tissue and thereby minimise the extent of the injury. Clinical examination should be carried out immediately after the injury and 5-7 days after the initial trauma, at which point the severity of the injury can be assessed more reliably. At that time, a more detailed characterisation of the injury can be made using imaging diagnostic modalities (ultrasound or MRI) if desired. The treatment of injured skeletal muscle should be carried out by immediate immobilisation of the injured muscle (clinically, relative immobility/avoidance of muscle contractions). However, the duration of immobilisation should be limited to a period sufficient to produce a scar of sufficient strength to bear the forces induced by remobilisation without re-rupture and the return to activity (mobilisation) should then be started gradually within the limits of pain. Early return to activity is needed to optimise the regeneration of healing muscle and recovery of the flexibility and strength of the injured skeletal muscle to pre-injury levels. The rehabilitation programme should be built around progressive agility and trunk stabilisation exercises, as these exercises seem to yield better outcome for injured skeletal muscle than programmes based exclusively on stretching and strengthening of the injured muscle.

Relationships between transforming growth factor-beta1, myostatin, and decorin: implications for skeletal muscle fibrosis

Recent studies have shown that myostatin, first identified as a negative regulator of skeletal muscle growth, may also be involved in the formation of fibrosis within skeletal muscle. In this study, we further explored the potential role of myostatin in skeletal muscle fibrosis, as well as its interaction with both transforming growth factor-beta1 and decorin. We discovered that myostatin stimulated fibroblast proliferation in vitro and induced its differentiation into myofibroblasts. We further found that transforming growth factor-beta1 stimulated myostatin expression, and conversely, myostatin stimulated transforming growth factor-beta1 secretion in C2C12 myoblasts. Decorin, a small leucine-rich proteoglycan, was found to neutralize the effects of myostatin in both fibroblasts and myoblasts. Moreover, decorin up-regulated the expression of follistatin, an antagonist of myostatin. The results of in vivo experiments showed that myostatin knock-out mice developed significantly less fibrosis and displayed better skeletal muscle regeneration when compared with wild-type mice at 2 and 4 weeks following gastrocnemius muscle laceration injury. In wild-type mice, we found that transforming growth factor-beta1 and myostatin co-localize in myofibers in the early stages of injury. Recombinant myostatin protein stimulated myofibers to express transforming growth factor-beta1 in skeletal muscles at early time points following injection. In summary, these findings define a fibrogenic property of myostatin and suggest the existence of co-regulatory relationships between transforming growth factor-beta1, myostatin, and decorin.

Matrix metalloproteinase-1 therapy improves muscle healing

Muscle undergoes time-dependent phases of healing after injury, which ultimately results in residual fibrosis in the injured area. The use of exogenous matrix metalloproteinases (MMPs) may improve recovery after muscle injury by promoting the digestion of existing fibrous tissue and releasing local growth factors. In the current experiment, bilateral gastrocnemius (GM) lacerations were created in severe combined immunodeficient mice. Twenty-five days after injury (peak posttraumatic fibrosis), C2C12 cells (myoblasts) transduced with the LacZ reporter gene were injected with exogenous MMP-1 into the right GMs at the site of injury; the cells were also injected along with PBS (control) at the site of injury in the left GMs. The muscle tissues were examined histologically via X-gal, hemotoxylin and eosin, and Masson's trichrome staining. The MMP-treated limbs contained more regenerating myofibers than did the control limbs (MMP 170 ± 96 fibers, control 62 ± 51 fibers; P < 0.001). Less fibrous tissue was observed within MMP-treated muscles (MMP: 24 ± 11%, control: 35 ± 15%; P < 0.01). These results suggest that the direct injection of MMP-1 into the zone of injury during fibrosis can enhance muscle regeneration by increasing the number of myofibers and decreasing the amount of fibrous tissue.

Muscle injuries

Muscle injuries are extremely common and may have a profound effect on the individual presenting with them. They are not reserved for professional athletes or indeed athletes at all but may occur equally in those with physically demanding jobs such as builders, labourers and gardeners. The key to successful treatment is accurate diagnosis and sound professional advice, ideally involving physiotherapists and other specialists. Given time, return to pre-injury activity is likely but not guaranteed as precocious return can lead to a chronic and debilitating injury.

Comparison of the relative benefits of 2 versus 10 days of soft collar cervical immobilization after acute whiplash injury

OBJECTIVE

To investigate the effects of 2-day and 10-day immobilization of the cervical spine on pain, range of motion (ROM), and disability of patients with Quebec Task Force (QTF) grade II whiplash injuries.

DESIGN

Randomized controlled trial.

SETTING

University hospital emergency department.

PARTICIPANTS

Seventy patients with acute QTF grade II whiplash injuries.

INTERVENTIONS

At the intake examination within 24 hours after the whiplash trauma, the patients were randomized to 2 therapy groups (2-d or 10-d immobilization with a soft cervical collar). All patients received pain drugs (nonsteroidal anti-inflammatory drugs) and after 7 days, all patients started a standardized physiotherapy program 2 to 3 times a week.

MAIN OUTCOME MEASURES

Patients' pain and disability scores were assessed using visual analog scales and ROM was assessed using a goniometer. All parameters were measured within 24 hours after injury and after 2 and 6 months.

RESULTS

After 2 months, the different periods of immobilization (2d or 10d) were associated with comparable improvements in pain symptoms (median, 4.60 vs 4.65), ROM (median, 100.0 degrees vs 117.5 degrees ), and disability score (median, 4.90 vs 5.15). No statistically significant differences could be identified between the 2 treatment groups. After 6 months, persistent pain was reported by 4 patients in each group (12.5%).

CONCLUSIONS

In patients with QTF grade II whiplash injuries, there is no short- or long-term difference between 2-day and 10-day immobilization with a cervical collar in terms of pain, ROM, or disability.

The ABJS Nicolas Andry Award: Tissue engineering of bone and ligament: a 15-year perspective

Musculoskeletal repair is a major challenge for orthopaedic surgeons. The burden of repair is compounded by supply constraints and morbidity associated with autograft and allograft tissue. We report 15 years of research regarding tissue engineering and biological substitutes for bone and ligaments. Our approach has focused on biomaterial selection, scaffold development, cell selection, cell/material interaction, and growth factor delivery. We have extensively tested poly(ester), poly(anhydride), poly(phosphazene) derivatives, and composite materials using biocompatibility, degradation, and mechanical analyses for bone and ligament tissue engineering. We have developed novel three-dimensional matrices with a pore structure and mechanical properties similar to native tissue. We also have reported on the attachment, growth, proliferation, and differentiation of cells cultured on several scaffolds. Through extensive molecular analysis, in vitro culture condition analysis, and in vivo evaluation, our findings provide new methods of bone tissue regeneration using three-dimensional tissue engineered scaffolds, bioactive bone cement composite materials, and three-dimensional tissue engineered scaffolds for ligament regeneration.

Pullout forces of sutures in muscle lacerations

The purpose of this study was to determine if complex suture techniques had higher pullout forces from muscle tissue than conventional stitching. Using transected cadaver muscle bellies, we performed repairs with various suture techniques and measured pullout forces. Epimyseal repair with conventional stitches (Kessler, figure eight, horizontal mattress) was inferior to complex stitches (modified Mason-Allen, perimeter). The combined complex stitches (perimeter and Mason-Allen) were strongest. Conventional stitches failed longitudinally through the muscle, whereas complex stitches failed transversely across the muscle. The complex combination of perimeter and Mason-Allen stitches had superior pullout resistance compared to conventional stitches.

Epimysium and perimysium in suturing in skeletal muscle lacerations

BACKGROUND

Direct muscle belly trauma is common. Selecting optimal methods for surgical repair of muscle disruption is difficult because reliable methods have not been established. Suturing tendon offers strong repairs, but epimysium and perimysium, the connective tissues that coalesce to form tendons, offer unknown repair strength. The purpose of this study was to compare biomechanical properties of repaired muscle in transected muscle bellies with epimysium and perimysium.

METHODS

The authors surgically repaired with figure-eight stitches in both epimysium and perimysium groups. Individual stitches were placed in lacerated quadriceps bellies from a euthanized pig and were tensioned on a biomechanical machine. Maximum loads and strains were measured, and failure mechanisms were recorded.

RESULTS

Loads and strains for repairs with epimysium were higher than those for repairs with perimysium. Failure mechanisms were significantly different between groups.

CONCLUSION

These data showed that epimysium incorporation into suturing improves capacity to bear forces compared with perimysium incorporation.

Hamstring injury management--Part 2: Treatment

The management of hamstring injuries can be described as vexed at best. One reason for this may be because of a lack of high-quality research into the methods of treatment, rehabilitation and prevention. As a result, an evidence-based approach to injury management does not exist. Management is based on clinical experience, anecdotal evidence and the knowledge of the biological basis of tissue repair. Previous hamstring injury is the most recognized risk factor for injury, which indicates that treatment approaches may be suboptimal under certain conditions. The identification of these risk factors and the methods best designed to manage them should be addressed with future research efforts. Much anecdotal and indirect evidence exists to suggest that several non-local factors contribute to injury. Despite the knowledge that these factors may exist, the literature appears almost devoid of research investigating their possible identification and treatment. Treatment has traditionally been in the form of altering the muscle repair process through the application of electrophysical therapy and various soft-tissue-based and exercise-based techniques. Little research has investigated the role of other forms of manual therapy particularly when directed at non-local structures. This paper will explore and speculate on this potential connection and offer some new contributive factors for hamstring injury management.

Muscle injuries: biology and treatment

Muscle injuries are one of the most common traumas occurring in sports. Despite their clinical importance, few clinical studies exist on the treatment of these traumas. Thus, the current treatment principles of muscle injuries have either been derived from experimental studies or been tested only empirically. Although nonoperative treatment results in good functional outcomes in the majority of athletes with muscle injuries, the consequences of failed treatment can be very dramatic, possibly postponing an athlete's return to sports for weeks or even months. Moreover, the recognition of some basic principles of skeletal muscle regeneration and healing processes can considerably help in both avoiding the imminent dangers and accelerating the return to competition. Accordingly, in this review, the authors have summarized the prevailing understanding on the biology of muscle regeneration. Furthermore, they have reviewed the existing data on the different treatment modalities (such as medication, therapeutic ultrasound, physical therapy) thought to influence the healing of injured skeletal muscle. In the end, they extend these findings to clinical practice in an attempt to propose an evidence-based approach for the diagnosis and optimal treatment of skeletal muscle injuries.

The management of hamstring injury—Part 1: Issues in diagnosis

Hamstring injuries are the most prevalent muscle injury in sports involving rapid acceleration and maximum speed running. Injury typically occurs in an acute manner through an eccentric mechanism at the terminal stages of the swing phase of gait. Biceps femoris is most commonly injured. Re-injury rates are high and management is a challenge given the complex multi-factorial aetiology. The high rates of hamstring injury and re-injury may result from a lack of high-quality research into the aetiological factors underlying injury. Re-injury may also result from inaccuracy in diagnosis that results from the potential multi-factorial causes of these conditions. Inaccuracy in diagnosis could lead to multiple potential diagnoses that may result in the implementation of variable management protocols. Whilst potentially useful, such variability may also lead to the implementation of sub-optimal management strategies. Previous hamstring injury is the most recognized risk factor for injury, which indicates that future research should be directed at preventative measures. Much anecdotal and indirect evidence exists to suggest that several non-local factors contribute to injury, which may be addressed through the application of manual therapy. However, this connection has been neglected in previous research and literature. This paper will explore and speculate on this potential connection and offer some new contributive factors for hamstring injury management. This first paper of a two part series on hamstring injury will explore diagnostic issues relevant to hamstring injury and the second will investigate various established and speculative management approaches.

The use of suramin, an antifibrotic agent, to improve muscle recovery after strain injury

BACKGROUND

Muscle strain injuries are extremely common in sports medicine. Muscle healing often is hindered by scar tissue formation after injury.

HYPOTHESIS

Suramin can prevent scar tissue formation and improve muscle healing after injury because of its ability to antagonize transforming growth factor-beta1, a fibrotic cytokine.

STUDY DESIGN

Controlled laboratory study.

MATERIALS AND METHODS

In vitro, muscle-derived fibroblasts (a potential cell source of muscle fibrosis) were incubated with suramin and/or transforming growth factor-beta1; a cell growth curve was obtained. In vivo, mouse gastrocnemius muscles were strain injured. Suramin or sham/control intramuscular injections were performed after injury at various time points. Mice were sacrificed at various time points after injury, and skeletal muscle tissue was evaluated by using histological and physiological tests. Statistical analysis was performed by using analysis of variance and Fisher tests.

RESULTS

Suramin decreased the stimulating effect of transforming growth factor-beta1 on the growth of muscle-derived fibroblasts in vitro. Significantly less fibrous scar formation was observed in suramin-treated muscles than in sham-injected muscles. The fast-twitch and tetanus strength of suramin-treated muscles was also significantly greater relative to that of control muscles.

CONCLUSIONS

Suramin blocked the stimulatory effect of transforming growth factor-beta1 on muscle-derived fibroblasts in vitro. Suramin also reduced fibrous scar formation in muscle and enhanced muscle strength in strain-injured skeletal muscle.

CLINICAL RELEVANCE

These results may facilitate the development of strategies to enhance muscle healing after injury.

The role of epimysium in suturing skeletal muscle lacerations

BACKGROUND

Direct muscle trauma is a common and disabling clinical problem. Surgical muscle repair is difficult to evaluate because reliable repair techniques have not been established scientifically. The purpose of this study was to assess the biomechanical properties of epimysium, the collagenous tissue sheath that surrounds muscles in the body.

STUDY DESIGN

We surgically repaired transected porcine muscle bellies with and without epimysium. For both groups, 25 figure-eight stitches in lacerated quadriceps bellies from a euthanatized pig were loaded under tension on a biomechanical machine (model 8521S, Instron Company). Maximum loads and strains were measured and mechanisms of failure recorded.

RESULTS

The mean load for repairs with epimysium (25.1 N) was significantly higher (p = 0.034) than that for repairs without epimysium (21.2 N). The mean strain for repairs with epimysium (10.4%) was significantly higher (p < 0.001) than that for repairs without epimysium (7.3%). The mechanisms of failure were also different. Among epimysium repairs, 15 stitches avulsed muscle transversely, and 10 stitches tore out longitudinally from the muscle. In the nonepimysium group, 1 suture avulsed muscle and 24 sutures tore out. Muscle was the weakest element in each test.

CONCLUSIONS

These data showed that epimysium incorporation into suturing improves the capacity of repairs to bear force. These findings fill a knowledge gap and may improve outcomes of muscle suturing. By focusing the experiment on biomechanical properties of muscle stitching, this study showed the key role epimysium plays in muscle suturing.

Restoration of myofiber continuity after transection injury in the rat soleus

In a shearing type of muscle injury, scar formation prevents restoration of myofiber continuity and the transected myofibers may become permanently divided into two separate myofibers. We have analysed whether the injured myofiber stumps can fuse and continuity of the transected fibers be re-established, if the stumps are surgically closely apposed immediately after injury. 55 rat soleus muscles were transected, after which the epimysium was carefully sutured and the leg was immobilised for seven days. The animals were sacrificed at 2, 5, 7, 10, 14 and 25 days after surgery. All muscles were analysed by light and electron microscopy as well as by immunohistochemistry. Mechanical strength was also measured at day 10 and 25. We observed that suturing reduced the extent of the intervening scar and accelerated healing. More importantly our results indicate that fusion of the stumps and thus restoration of myofiber continuity, is possible after myofiber transection injury.

Acute ankle injury and chronic lateral instability in the athlete

Ankle injuries occur frequently in sports. The lateral ligamentous complex, specifically the anterior talofibular and calcaneofibular ligaments, are most commonly injured. In acute lateral ligament injuries, a functional ankle rehabilitation program is the mainstay of treatment. Chronic ankle instability develops in a minority of patients. Surgical procedures are broadly classified into anatomic ligament repairs versus reconstructive tenodeses. Commonly performed techniques include the Brostrom-Gould procedure,the modified Brostrum-Evans procedure, and the Chrisman-Snook procedure.

Rehabilitation of fractures in small animals: Maximize outcomes, minimize complications

Successful fracture management accomplishes 2 major objectives: bony union and return to functional activities. For many years, Physical Therapy has routinely helped human patients recovering from fractures reach their functional goals by helping them regain movement, flexibility, strength, coordination, and balance. Rehabilitation is now commonly provided to small animals recovering from fractures to accomplish similar goals. Knowledge of tissue healing is critical when determining the appropriate stresses to apply throughout the healing timeline. The detrimental effects of immobilization, including the potential for development of fracture disease, must be considered when formulating a Rehabilitation plan of care. Many Rehabilitation interventions are readily amenable to application by both Veterinary professionals and owners of patients. Superficial thermal modalities, passive range of motion and stretching, soft tissue massage, therapeutic ultrasound, electrical stimulation, and therapeutic exercise can ensure a more complete patient recovery. Providing owners with education regarding appropriate patient handling and home modifications allows a safer return to the home environment. Detailed written instructions for rehabilitation at home promotes owner compliance and accurate completion.

Factors Associated with Recurrent Hamstring Injuries

A history of muscle injury represents a predominant risk factor for future insult in that muscle group. The high frequency of re-injury and persistent complaints after a hamstring strain comprise major difficulties for the athlete on return to athletic activities. Some of the risk factors associated with the possible recurrence of the injury are, in all probability, already implicated in the initial injury. One can distinguish between those events peculiar to the sport activity modalities (extrinsic factors) and other contributing factors based on the athletes individual features (intrinsic factors). For both categories, the persistence of mistakes or abnormalities in action represent an irrefutable component contributing to the re-injury cycle. Additional factors leading to chronicity can come from the first injury per se through modifications in the muscle tissue and possible adaptive changes in biomechanics and motor patterns of sporting movements. We emphasise the role of questionable approaches to the diagnosis process, drug treatment or rehabilitation design. To date, the risk factors examined in the literature have either been scientifically associated with injury and/or speculated to be associated with injury. In this context, quantifying the real role of each factor remains hypothetical, the most likely ones corresponding to inadequate warm-up, invalid structure and the content of training, muscle tightness and/or weakness, agonist/antagonist imbalances, underestimation of an extensive injury, use of inappropriate drugs, presence of an extensive scar tissue and, above all, incomplete or aggressive rehabilitation. Such a list highlights the unavoidable necessity of developing valid assessment methods, the use of specific measurement tools and more rigorous guidelines in the treatment and rehabilitation. This also implies a scientific understanding as well as specifically qualified medical doctors, physiotherapists and trainers acting in partnership.

Improvement of muscle healing through enhancement of muscle regeneration and prevention of fibrosis

Skeletal muscle is able to repair itself through regeneration. However, an injured muscle often does not fully recover its strength because complete muscle regeneration is hindered by the development of fibrosis. Biological approaches to improve muscle healing by enhancing muscle regeneration and reducing the formation of fibrosis are being investigated. Previously, we have determined that insulin-like growth factor-1 (IGF-1) can improve muscle regeneration in injured muscle. We also have investigated the use of an antifibrotic agent, decorin, to reduce muscle fibrosis following injury. The aim of this study was to combine these two therapeutic methods in an attempt to develop a new biological approach to promote efficient healing and recovery of strength after muscle injuries. Our findings indicate that further improvement in the healing of muscle lacerations is attained histologically by the combined administration of IGF-1 to enhance muscle regeneration and decorin to reduce the formation of fibrosis. This improvement was not associated with improved responses to physiological testing, at least at the time-points tested in this study.

Antifibrotic effects of suramin in injured skeletal muscle after laceration

Muscle injuries are very common in traumatology and sports medicine. Although muscle tissue can regenerate postinjury, the healing process is slow and often incomplete; complete recovery after skeletal muscle injury is hindered by fibrosis. Our studies have shown that decreased fibrosis could improve muscle healing. Suramin has been found to inhibit transforming growth factor (TGF)-beta1 expression by competitively binding to the growth factor receptor. We conducted a series of tests to determine the antifibrotic effects of suramin on muscle laceration injuries. Our results demonstrate that suramin (50 microg/ml) can effectively decrease fibroblast proliferation and fibrotic-protein expression (alpha-smooth muscle actin) in vitro. In vivo, direct injection of suramin (2.5 mg) into injured murine muscle resulted in effective inhibition of muscle fibrosis and enhanced muscle regeneration, which led to efficient functional muscle recovery. These results support our hypothesis that prevention of fibrosis could enhance muscle regeneration, thereby facilitating more efficient muscle healing. This study could significantly contribute to the development of strategies to promote efficient muscle healing and functional recovery.

Basic science and clinical studies coincide: active treatment approach is needed after a sports injury

The basic response to injury at the tissue level is well known and consists of acute inflammatory phase, proliferative phase, and maturation and remodeling phase. Knowing these phases, the treatment and rehabilitation program of athletes' acute musculoskeletal injuries should use a short period of immobilization followed by controlled and progressive mobilization. Both experimental and clinical trials have given systematic and convincing evidence that this program is superior to immobilization - a good example where basic science and clinical studies do coincide - and therefore active approach is needed in the treatment of these injuries.

Muscle contusion injury and myositis ossificans traumatica

In athletic competition, muscle contusion injury is a frequent and debilitating condition. Found in traditional contact and noncontact sports, contusions also can occur to the nonathlete by simple falls and accidents. The injury consists of a well-defined sequence of events involving microscopic rupture and damage to muscle cells, macroscopic defects in muscle bellies, infiltrative bleeding, and inflammation. The repair of the tissue can be thought of as a race between remodeling and scar formation. In the current study, the authors describe the relevant body of research directed at delineating the incidence, factors that affect injury severity, and treatment of muscle contusion injury. Emphasis is given to animal models that allow reproducible, quantitative injury, and study of the effects of various treatment modalities. Myositis ossificans traumatica, one of the most debilitating consequences of contusion injuries, also is discussed. The incidence, causative factors, and prevention strategies are reviewed.

Surgical repair of acute traumatic closed transection of the biceps brachii

BACKGROUND

Effective techniques to repair transected muscles are not well described. We determined the outcome of surgically repaired closed transections of the biceps muscle with regard to strength, appearance, and patient satisfaction.

METHODS

We conducted a study on surgical repair of acute traumatic closed transection of the muscle belly of the biceps brachii in paratroopers. Muscle fibers and epimysium were sutured with use of running interlocked stitches as well as modified Mason-Allen stitches. We gathered data on the supination torque, appearance of the arm, and patient satisfaction. Nine patients underwent surgical repair and were followed for a mean of 2.2 years. Three patients, who constituted a comparative group, had nonoperative treatment of complete transections of the biceps and were followed for a mean of eleven years.

RESULTS

We found that the patients who had surgical repair had better results than did those who had nonoperative treatment, with respect to supination torque (a mean of 11.0 N-m compared with 5.8 N-m, p = 0.0005), appearance (a mean of 4.6 cm compared with 3.0 cm, according to the cosmetic visual analog scale; p = 0.000002), and satisfaction (excellent in all nine patients who had surgical repair and satisfactory in all three who had nonoperative treatment).

CONCLUSIONS

The results after repair of acute traumatic closed transection of the biceps brachii with the new surgical technique described in the present study demonstrated a significant improvement in terms of function, appearance, and patient satisfaction compared with those after nonoperative treatment.

The effect of bed rest and potential of prehabilitation on patients in the intensive care unit

Declines in physical activity that accompany an admission to an intensive care unit (ICU) represent a significant stress to the body. Decreases in physical activity have been demonstrated to result in losses in functional capacity of the musculoskeletal and cardiovascular systems. These two systems are central to achieving and maintaining functional independence, which is a prerequisite for discharge from a healthcare facility, as is independent functioning of the individual in the community setting. Whereas a decrease in physical activity will result in an attenuation in the functioning of the cardiovascular and musculoskeletal systems, increases in physical activity can stimulate gains in their functional capacity. The concept of improving the functional capacity of the body to withstand anticipated musculoskeletal stressors has had limited application to the effects of inactivity associated with an ICU admission. By increasing an individual's functional capacity through increased physical activity prior to an ICU admission, it seems reasonable that the patient would retain a higher level of functional capacity over their entire ICU admission. The process of enhancing functional capacity of the individual to enable them to withstand the stressor of inactivity associated with an admission to ICU is termed prehabilitation. A generic program of prehabilitation includes warm-up, aerobic, strength, flexibility, and functional task components. The initial level of prehabilitation training and the progression of the training will be different for each individual based upon their initial functional capacity and the degree to which they individually respond to increases in physical activity. Declines in physical activity among ICU patients represents a significant health risk that may be reduced through introducing prehabilitation interventions.