Injuries to runners

Platelet-Poor versus Platelet-Rich Plasma for the Treatment of Muscle Injuries

ABSTRACT

Muscle injury in sport results in significant lost time and potential for reinjury for athletes. Autologous blood product, namely, platelet-rich plasma (PRP), has been investigated for possible augmentation of the treatment timeline with prevention of reinjury; however, conflicting results have been identified. A growing body of basic science and clinical literature is forming that supports the use of platelet-poor plasma (PPP) for muscle injury. The purpose of this study was to provide a background of the basic science of PRP versus PPP for muscle injury and to identify and review the clinical evidence for both autologous blood products, including the author's clinical experience utilizing the blood products. At the tissue level, PRP causes myoblast proliferation while PPP has led to myoblast induction, potentially identifying improved native muscle healing. Conflicting studies have been identified for the use of PRP for muscle injury. A growing body of positive results for PPP was identified, but high-quality comparative studies are needed.

Towards functionally individualised designed footwear recommendation for overuse injury prevention: a scoping review

Injury prevention is essential in running due to the risk of overuse injury development. Tailoring running shoes to individual needs may be a promising strategy to reduce this risk. Novel manufacturing processes allow the production of individualised running shoes that incorporate features that meet individual biomechanical and experiential needs. However, specific ways to individualise footwear to reduce injury risk are poorly understood. Therefore, this scoping review provides an overview of (1) footwear design features that have the potential for individualisation; and (2) the literature on the differential responses to footwear design features between selected groups of individuals. These purposes focus exclusively on reducing the risk of overuse injuries. We included studies in the English language on adults that analysed: (1) potential interaction effects between footwear design features and subgroups of runners or covariates (e.g., age, sex) for running-related biomechanical risk factors or injury incidences; (2) footwear comfort perception for a systematically modified footwear design feature. Most of the included articles (n = 107) analysed male runners. Female runners may be more susceptible to footwear-induced changes and overuse injury development; future research should target more heterogonous sampling. Several footwear design features (e.g., midsole characteristics, upper, outsole profile) show potential for individualisation. However, the literature addressing individualised footwear solutions and the potential to reduce biomechanical risk factors is limited. Future studies should leverage more extensive data collections considering relevant covariates and subgroups while systematically modifying isolated footwear design features to inform footwear individualisation.

Longitudinal Tibia Stress Fracture Risk During High-Volume Training: a Multi-Scale Modeling Pipeline Incorporating Bone Remodeling

Tibia stress fractures are prevalent during high-intensity training, yet a mechanistic model linking longitudinal training intensity, bone health, and long-term injury risk has yet to be demonstrated. The objective of this study was to develop and validate a multi-scale model of gross and tissue level loading on the tibia including bone remodeling on a timescale of week. Peak tensile tibial strain (3517 µstrain) during 4 m/s running was below injury thresholds, and the peak anteromedial tibial strain (1248 µstrain) was 0.17 standard deviations away from the mean of reported literature values. An initial study isolated the effects of cortical density and stiffness on tibial strain during a simulated eight week training period. Tibial strains and cortical microcracking correlated to initial cortical modulus, with all simulations presenting peak anteromedial tensile strains (1047-1600 µstrain) near day 11. Average cortical densities decreased by 7-8 percent of their nominal value by day 11, but the overall density change was <2% by the end of the simulated training period, in line with reported results. This study demonstrates the benefits of multi-scale models for investigating stress fracture risk and indicates that peak tibial strain, and thus injury risk, may increase early in a high intensity training program. Future studies could optimize training volume and recovery time to reduce injury risk during the most vulnerable training periods.

Distal Hamstring Muscle Injuries

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Distal hamstring muscle injuries, although relatively uncommon, can potentially lead to substantial morbidity in athletes; prolonged rehabilitation times and high rates of reoccurrence have been documented.

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Overall, magnetic resonance imaging is considered the "gold standard" for evaluation of hamstring injuries because it allows assessment for concomitant pathology and can clarify return-to-sport timelines.

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Complete tears of the distal biceps femoris and semimembranosus muscles respond well to surgical repair, whereas complete tears of the distal semitendinosus can be successfully treated nonoperatively or with surgical resection.

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Future research may be necessary to further optimize treatment of these injuries and to determine the efficacy of biologic adjuvant therapy.

A systematic review of running-related musculoskeletal injuries in runners

OBJECTIVE

Running-related musculoskeletal injuries (RRMIs), especially stemming from overuse, frequently occur in runners. This study aimed to systematically review the literature and determine the incidence and prevalence proportion of RRMIs by anatomic location and specific pathology.

METHODS

An electronic database search with no date beginning restrictions was performed in SPORTDiscus, PubMed, and MEDLINE up to June 2020. Prospective studies were used to find the anatomic location and the incidence proportion of each RRMI, whereas retrospective or cross-sectional studies were used to find the prevalence proportion of each RRMI. A separate analysis for ultramarathon runners was performed.

RESULTS

The overall injury incidence and prevalence were 40.2% ± 18.8% and 44.6% ± 18.4% (mean ± SD), respectively. The knee, ankle, and lower leg accounted for the highest proportion of injury incidence, whereas the knee, lower leg, and foot/toes had the highest proportion of injury prevalence. Achilles tendinopathy (10.3%), medial tibial stress syndrome (9.4%), patellofemoral pain syndrome (6.3%), plantar fasciitis (6.1%), and ankle sprains (5.8%) accounted for the highest proportion of injury incidence, whereas patellofemoral pain syndrome (16.7%), medial tibial stress syndrome (9.1%), plantar fasciitis (7.9%), iliotibial band syndrome (7.9%), and Achilles tendinopathy (6.6%) had the highest proportion of injury prevalence. The ankle (34.5%), knee (28.1%), and lower leg (12.9%) were the 3 most frequently injured sites among ultramarathoners.

CONCLUSION

The injury incidence proportions by anatomic location between ultramarathoners and non-ultramarathoners were not significantly different (p = 0.798). The pathologies with the highest incidence proportion of injuries were anterior compartment tendinopathy (19.4%), patellofemoral pain syndrome (15.8%), and Achilles tendinopathy (13.7%). The interpretation of epidemiological data in RRMIs is limited due to several methodological issues encountered.

Hamstring muscle injury in the athlete: state of the art

Hamstring injuries (HSI) are the source of significant impairment and disability for both professional and recreational athletes. The incidence and prevalence of HSIs has been well documented in the literature, as they are among the most common soft tissue injuries reported. The significant time loss due to injury and the inherent risk of reinjury pose a significant issue to the athlete, their career longevity and the success of their respective team. This review will deal predominantly with describing the prevalence and incidence of HSI in athletes, discuss risk factors and the mechanisms of injury for HSI, how to properly diagnose, image and prognosticate appropriate return to sport (RTS) for individuals who have sustained an HSI, prescribe treatment and prevention strategies and to discuss relevant options to decrease overall risk of primary and secondary recurrence of HSI.Current treatments of acute HSI necessitate a thorough understanding of the mechanism of injury, identifying muscle imbalances and/or weakness, inclusion of eccentric and concentric hamstring (HS) and hip extension (HE) exercises, evaluation of pathokinematic movement patterns and use non-surgical methods to promote healing and RTS. This methodology can be used prospectively to mitigate the overall risk of HSI. Injection therapies for HSI, including ultrasound-guided platelet-rich plasma and corticosteroids, may impart some short-term benefit, but the existing literature is largely inconclusive with respect to long-term functional outcomes. Future directions should prioritise injury prevention, early diagnosis and targeted interventions that combine both non-surgical and minimally invasive orthobiological approaches and identifying biomechanical risk factors prospectively to mitigate risk.

A comparison of the free moment pattern between normal and hyper-pronated aligned feet in female subjects during the stance phase of gait

BACKGROUND

Excessive range of adductory free moment of the ground reaction force may potentially increase the risk of lower extremity injuries by applying a higher torsional load transmitted to the proximal parts.

OBJECTIVE

It was hypothesized that the free moment pattern might be different between hyper-pronated and normal feet subjects. Moreover, a correlation would exist between peak adduction free moment and peak ankle-foot complex abduction at the stance phase of walking.

MATERIAL AND METHODS

In this cross sectional study, thirty female participants were divided into two groups of asymptomatic hyper-pronated and normal feet. Kinetic and kinematic data were collected using a single force plate and a six-camera motion analysis system during three successful free speed walking trials. Ensemble average curves were extracted from the time normalized individual trials of the stance phase for both free moment and peak ankle-foot complex abduction parameters.

RESULTS

Significant differences in peak adductory free moment, peak ankle-foot complex eversion and peak ankle-foot complex abduction were found between normal and hyper-pronated groups (4.90±0.97 Vs. 5.94±0.88, P < 0.01), (3.30±0.95 Vs. 6.28±1.47, P < 0.01) and (4.52±1.16 Vs. 8.23±2.52, P < 0.01) respectively. A significant positive correlation was found between the peak adduction free moment and peak ankle-foot complex abduction in both groups, which was more strongly positive in hyper-pronated group (r = 0.745, p < 0.01 for normal group and r = 0.900, p < 0.01 for hyper-pronated group).

CONCLUSION

As a good measure of torque which is transmitted to the lower extremity, may free moment be a useful biomechanical indicator for both clinical and research purposes.

Mechanical Fatigue of Bovine Cortical Bone Using Ground Reaction Force Waveforms in Running

Stress fractures are a common overuse injury among runners associated with the mechanical fatigue of bone. Several in vivo biomechanical studies have investigated specific characteristics of the vertical ground reaction force (vGRF) in heel-toe running and have observed an association between increased loading rate during impact and individuals with a history of stress fracture. The purpose of this study was to examine the fatigue behavior of cortical bone using vGRF-like loading profiles, including those that had been decomposed into their respective impact and active phase components. Thirty-eight cylindrical cortical bone samples were extracted from bovine tibiae and femora. Hydrated samples were fatigue tested at room temperature in zero compression under load control using either a raw (n = 10), active (n = 10), low impact (n = 10), or high impact (n = 8) vGRF profile. The number of cycles to failure was quantified and the test was terminated if the sample survived 105 cycles. Fatigue life was significantly greater for both impact groups compared to the active (p < 0.001) and raw (p < 0.001) groups, with all low impact samples and 6 of 8 high impact samples surviving 105 cycles. The mean (± SD) number of cycles to failure for the active and raw groups was 12,133±11,704 and 16,552±29,612, respectively. The results suggest that loading rates associated with the impact phase of a typical vGRF in running have little influence on the mechanical fatigue behavior of bone relative to loading magnitude, warranting further investigation of the mechanism by which increased loading rates are associated with stress fracture.

Effects of footwear and stride length on metatarsal strains and failure in running

BACKGROUND

The metatarsal bones of the foot are particularly susceptible to stress fracture owing to the high strains they experience during the stance phase of running. Shoe cushioning and stride length reduction represent two potential interventions to decrease metatarsal strain and thus stress fracture risk.

METHODS

Fourteen male recreational runners ran overground at a 5-km pace while motion capture and plantar pressure data were collected during four experimental conditions: traditional shoe at preferred and 90% preferred stride length, and minimalist shoe at preferred and 90% preferred stride length. Combined musculoskeletal - finite element modeling based on motion analysis and computed tomography data were used to quantify metatarsal strains and the probability of failure was determined using stress-life predictions.

FINDINGS

No significant interactions between footwear and stride length were observed. Running in minimalist shoes increased strains for all metatarsals by 28.7% (SD 6.4%; p<0.001) and probability of failure for metatarsals 2-4 by 17.3% (SD 14.3%; p≤0.005). Running at 90% preferred stride length decreased strains for metatarsal 4 by 4.2% (SD 2.0%; p≤0.007), and no differences in probability of failure were observed.

INTERPRETATIONS

Significant increases in metatarsal strains and the probability of failure were observed for recreational runners acutely transitioning to minimalist shoes. Running with a 10% reduction in stride length did not appear to be a beneficial technique for reducing the risk of metatarsal stress fracture, however the increased number of loading cycles for a given distance was not detrimental either.

Prevention of Hamstring Injuries in Collegiate Sprinters

BACKGROUND

No studies have been reported on how strength, agility, and flexibility training reduce the occurrence of hamstring injuries in sprinters. Therefore, a program for preventing hamstring injury in these athletes has not been established.

PURPOSE

To document the incidence of hamstring injuries during times when different prevention strategies were employed to see whether a particular prevention program reduced their occurrence.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

The study subjects were a total of 613 collegiate male sprinters trained by the same coach over 24 seasons. Tow training was used throughout the research period as a normal sprint training method. The hamstring injury prevention program evolved over time. From 1988 to 1991 (period 1), prevention focused on strength training alone; from 1992 to 1999 (period 2), a combination of strength and agility training was used; and from 2000 to 2011 (period 3), the program incorporated strength, agility, and flexibility training. The incidence of hamstring injuries was compared for each of the 3 prevention strategies.

RESULTS

The incidence of hamstring injuries per athlete-seasons was 137.9 for period 1, 60.6 for period 2, and 6.7 for period 3. A significant difference was observed in the incidence of hamstring injury according to the different prevention programs (χ²(2) = 31.78, P < .001, effect size: Cramer V = 0.23, 1 - β = 0.999). Residual analysis showed that the number of hamstring injuries for period 1 was significantly greater than the expected value (P < .01), whereas that for period 3 was significantly lower than the expected value (P < .01).

CONCLUSION

The incidence of hamstring injuries in sprinters decreased as agility and flexibility were added to strength training.

A qualitative and quantitative analysis of the attachment sites of the proximal hamstrings

PURPOSE

Proximal hamstring tears represent a challenge. Surgical repair of such tears has been reported utilizing both open and endoscopic techniques. It was hypothesized that the proximal attachments of the hamstring muscle group could be reproducibly and consistently measured from pertinent bony anatomical reference landmarks.

METHODS

Fourteen fresh-frozen, human cadaveric specimens were dissected, and measurements were taken regarding the proximal attachments of the hamstring muscle group in reference to bony landmarks. A highly precise coordinate measuring device was used for three-dimensional measurements of tendon footprints and bony landmarks, and relevant distances between structures were calculated.

RESULTS

The semitendinosus and long head of the biceps femoris shared a proximal origin (conjoined tendon), having an oval footprint with an average area of 567.0 mm(2) [95 % CI 481.0-652.9]. The semimembranosus (SM) footprint was crescent-shaped and located anterolateral to the conjoined tendon, with an average area of 412.4 mm(2) [95 % CI 371.0-453.8]. The SM footprint had an accessory tendinous extension that extended anteromedially forming a distinct footprint. A consistent bony landmark was found at the medial ischial margin, 14.6 mm [95 % CI 12.7-16.5] from the centre of the conjoined tendon footprint, which coincided with the distal insertion of the sacrotuberous ligament.

CONCLUSION

The conjoined tendon was the largest attachment of the proximal hamstring group. Two other distinct attachment footprints were identified as the SM footprint and the accessory tendinous extension. The sacrotuberous ligament insertion served as a bony landmark. The anatomical data established in this study may aid in better restoring the anatomy during repair of proximal hamstring tears.

A qualitative and quantitative analysis of the attachment sites of the proximal hamstrings

PURPOSE

Proximal hamstring tears represent a challenge. Surgical repair of such tears has been reported utilizing both open and endoscopic techniques. It was hypothesized that the proximal attachments of the hamstring muscle group could be reproducibly and consistently measured from pertinent bony anatomical reference landmarks.

METHODS

Fourteen fresh-frozen, human cadaveric specimens were dissected, and measurements were taken regarding the proximal attachments of the hamstring muscle group in reference to bony landmarks. A highly precise coordinate measuring device was used for three-dimensional measurements of tendon footprints and bony landmarks, and relevant distances between structures were calculated.

RESULTS

The semitendinosus and long head of the biceps femoris shared a proximal origin (conjoined tendon), having an oval footprint with an average area of 567.0 mm(2) [95 % CI 481.0-652.9]. The semimembranosus (SM) footprint was crescent-shaped and located anterolateral to the conjoined tendon, with an average area of 412.4 mm(2) [95 % CI 371.0-453.8]. The SM footprint had an accessory tendinous extension that extended anteromedially forming a distinct footprint. A consistent bony landmark was found at the medial ischial margin, 14.6 mm [95 % CI 12.7-16.5] from the centre of the conjoined tendon footprint, which coincided with the distal insertion of the sacrotuberous ligament.

CONCLUSION

The conjoined tendon was the largest attachment of the proximal hamstring group. Two other distinct attachment footprints were identified as the SM footprint and the accessory tendinous extension. The sacrotuberous ligament insertion served as a bony landmark. The anatomical data established in this study may aid in better restoring the anatomy during repair of proximal hamstring tears.

Torsion and antero-posterior bending in the in vivo human tibia loading regimes during walking and running

Bending, in addition to compression, is recognized to be a common loading pattern in long bones in animals. However, due to the technical difficulty of measuring bone deformation in humans, our current understanding of bone loading patterns in humans is very limited. In the present study, we hypothesized that bending and torsion are important loading regimes in the human tibia. In vivo tibia segment deformation in humans was assessed during walking and running utilizing a novel optical approach. Results suggest that the proximal tibia primarily bends to the posterior (bending angle: 0.15°-1.30°) and medial aspect (bending angle: 0.38°-0.90°) and that it twists externally (torsion angle: 0.67°-1.66°) in relation to the distal tibia during the stance phase of overground walking at a speed between 2.5 and 6.1 km/h. Peak posterior bending and peak torsion occurred during the first and second half of stance phase, respectively. The peak-to-peak antero-posterior (AP) bending angles increased linearly with vertical ground reaction force and speed. Similarly, peak-to-peak torsion angles increased with the vertical free moment in four of the five test subjects and with the speed in three of the test subjects. There was no correlation between peak-to-peak medio-lateral (ML) bending angles and ground reaction force or speed. On the treadmill, peak-to-peak AP bending angles increased with walking and running speed, but peak-to-peak torsion angles and peak-to-peak ML bending angles remained constant during walking. Peak-to-peak AP bending angle during treadmill running was speed-dependent and larger than that observed during walking. In contrast, peak-to-peak tibia torsion angle was smaller during treadmill running than during walking. To conclude, bending and torsion of substantial magnitude were observed in the human tibia during walking and running. A systematic distribution of peak amplitude was found during the first and second parts of the stance phase.

Health and exercise-related medical issues among 1,212 ultramarathon runners: baseline findings from the Ultrarunners Longitudinal TRAcking (ULTRA) Study

Regular exercise is associated with substantial health benefits; however, little is known about the health impact of extreme levels of exercise. This study examined the prevalence of chronic diseases, health-care utilization, and risk factors for exercise-related injuries among ultramarathon runners. Retrospective, self-reported enrollment data from an ongoing longitudinal observational study of 1,212 active ultramarathon runners were analyzed. The most prevalent chronic medical conditions were allergies/hay fever (25.1%) and exercise-induced asthma (13.0%), but there was a low prevalence of serious medical issues including cancers (4.5%), coronary artery disease (0.7%), seizure disorders (0.7%), diabetes (0.7%), and human immunodeficiency virus (HIV) infection (0.2%). In the year preceding enrollment, most (64.6%) reported an exercise-related injury that resulted in lost training days (median of 14 days), but little nonattendance of work or school due to illness, injury, or exercise-related medical conditions (medians of 0 days for each). The knee was the most common area of exercise-related injury. Prior year incidence of stress fractures was 5.5% with most (44.5%) involving the foot. Ultramarathon runners who sustained exercise-related injuries were younger (p<0.001) and less experienced (p<0.01) than those without injury. Stress fractures were more common (p<0.01) among women than men. We conclude that, compared with the general population, ultramarathon runners appear healthier and report fewer missed work or school days due to illness or injury. Ultramarathon runners have a higher prevalence of asthma and allergies than the general population, and the prevalence of serious medical issues was nontrivial and should be recognized by those providing medical care to these individuals. Ultramarathon runners, compared with shorter distance runners, have a similar annual incidence of exercise-related injuries but higher proportion of stress fractures involving the foot, and it is the younger and less experienced ultramarathoners who appear most at risk for injury.

Evaluation and management of hamstring injuries

Muscle injuries are the most common injuries in sports, with hamstring injuries accounting for 29% of all injuries in athletes. These injuries lead to prolonged impairment and have a reinjury risk of 12% to 31%. They range from mild muscle damage without loss of structural integrity to complete muscle tearing with fiber disruption. Novel MRI scores are increasingly being used and allow a more precise prediction of return to sport. In this article, the authors review the history, mechanisms of injury, and classification systems for hamstring injuries as well as present the latest evidence related to the management of hamstring injuries, including intramuscular and both proximal and distal insertional injuries. Indications for surgical treatment of certain proximal and distal avulsions, biological augmentation to the nonoperative treatment of midsubstance injuries, and advances in risk reduction and injury prevention are discussed.

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.

Injury rates and injury risk factors among Federal Bureau of Investigation new agent trainees

BACKGROUND

A one-year prospective examination of injury rates and injury risk factors was conducted in Federal Bureau of Investigation (FBI) new agent training.

METHODS

Injury incidents were obtained from medical records and injury compensation forms. Potential injury risk factors were acquired from a lifestyle questionnaire and existing data at the FBI Academy.

RESULTS

A total of 426 men and 105 women participated in the project. Thirty-five percent of men and 42% of women experienced one or more injuries during training. The injury incidence rate was 2.5 and 3.2 injuries/1,000 person-days for men and women, respectively (risk ratio (women/men) = 1.3, 95% confidence interval = 0.9-1.7). The activities most commonly associated with injuries (% of total) were defensive tactics training (58%), physical fitness training (20%), physical fitness testing (5%), and firearms training (3%). Among the men, higher injury risk was associated with older age, slower 300-meter sprint time, slower 1.5-mile run time, lower total points on the physical fitness test (PFT), lower self-rated physical activity, lower frequency of aerobic exercise, a prior upper or lower limb injury, and prior foot or knee pain that limited activity. Among the women higher injury risk was associated with slower 300-meter sprint time, slower 1.5-mile run time, lower total points on the PFT, and prior back pain that limited activity.

CONCLUSION

The results of this investigation supported those of a previous retrospective investigation emphasizing that lower fitness and self-reported pain limiting activity were associated with higher injury risk among FBI new agents.

Retrospective examination of injuries and physical fitness during Federal Bureau of Investigation new agent training

Background

A retrospective examination was conducted of injuries, physical fitness, and their association among Federal Bureau of Investigation (FBI) new agent trainees.

Methods

Injuries and activities associated with injuries were obtained from a review of medical records in the medical clinic that served the new agents. A physical fitness test (PFT) was administered at Weeks 1, 7 and 14 of the 17-week new agent training course. The PFT consisted of push-ups, sit-ups, pull-ups, a 300-meter sprint, and a 1.5-mile run. Injury data were available from 2000 to 2008 and fitness data were available from 2004 to early 2009.

Results

During the survey period, 37% of men and 44% of women experienced one or more injuries during the new agent training course (risk ratio (women/men) = 1.18, 95% confidence interval = 1.07-1.31). The most common injury diagnoses were musculoskeletal pain (not otherwise specified) (27%), strains (11%), sprains (10%), contusions (9%), and abrasions/lacerations (9%). Activities associated with injury included defensive tactics training (48%), physical fitness training (26%), physical fitness testing (6%), and firearms training (6%). Over a 6-year period, there was little difference in performance of push-ups, sit-ups, pull-ups, or the 300-meter sprint; 1.5-mile run performance was higher in recent years. Among both men and women, higher injury incidence was associated with lower performance on any of the physical fitness measures.

Conclusion

This investigation documented injury diagnoses, activities associated with injury, and changes in physical fitness, and demonstrated that higher levels of physical fitness were associated with lower injury risk.

Barefoot running claims and controversies: a review of the literature

BACKGROUND

Barefoot running is slowly gaining a dedicated following. Proponents of barefoot running claim many benefits, such as improved performance and reduced injuries, whereas detractors warn of the imminent risks involved.

METHODS

Multiple publications were reviewed using key words.

RESULTS

A review of the literature uncovered many studies that have looked at the barefoot condition and found notable differences in gait and other parameters. These findings, along with much anecdotal information, can lead one to extrapolate that barefoot runners should have fewer injuries, better performance, or both. Several athletic shoe companies have designed running shoes that attempt to mimic the barefoot condition and, thus, garner the purported benefits of barefoot running.

CONCLUSIONS

Although there is no evidence that either confirms or refutes improved performance and reduced injuries in barefoot runners, many of the claimed disadvantages to barefoot running are not supported by the literature. Nonetheless, it seems that barefoot running may be an acceptable training method for athletes and coaches who understand and can minimize the risks.

A description of shock attenuation for children running

CONTEXT

A growing number of children are participating in organized sport activities, resulting in a concomitant increase in lower extremity injuries. Little is known about the impact generated when children are running or how this impact is attenuated in child runners.

OBJECTIVE

To describe shock attenuation characteristics for children running at different speeds on a treadmill and at a single speed over ground.

DESIGN

Prospective cohort study.

SETTING

Biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

Eleven boys (age = 10.5 +/- 0.9 years, height = 143.7 +/- 8.3 cm, mass = 39.4 +/- 10.9 kg) and 7 girls (age = 9.9 +/- 1.1 years, height = 136.2 +/- 7.7 cm, mass = 35.1 +/- 9.6 kg) participated.

INTERVENTION(S)

Participants completed 4 running conditions, including 3 treadmill (TM) running speeds (preferred, fast [0.5 m/s more than preferred], and slow [0.5 m/s less than preferred]) and 1 overground (OG) running speed.

MAIN OUTCOME MEASURE(S)

We measured leg peak impact acceleration (LgPk), head peak impact acceleration (HdPk), and shock attenuation (ratio of LgPk to HdPk).

RESULTS

Shock attenuation (F(2,16) = 4.80, P = .01) was influenced by the interaction of speed and sex. Shock attenuation increased across speeds (slow, preferred, fast) for boys (P < .05) but not for girls (P > .05). Both LgPk (F(1,16) = 5.04, P = .04) and HdPk (F(1,16) = 6.04, P = .03) were different across speeds, and both were greater for girls than for boys. None of the dependent variables were influenced by the interaction of setting (TM, OG) and sex (P >or= .05). Shock attenuation (F(1,16) = 33.51, P < .001) and LgPk (F(1,16) = 31.54, P < .001) were different between TM and OG, and each was greater when running OG than on the TM, regardless of sex.

CONCLUSIONS

Shock attenuation was between 66% and 76% for children running under a variety of conditions. Girls had greater peak impact accelerations at the leg and head levels than boys but achieved similar shock attenuation. We do not know how these shock attenuation characteristics are related to overuse injuries.

Effects of running speed on a probabilistic stress fracture model

BACKGROUND

Stress fractures are dependent on both loading magnitude and loading exposure. Decreasing speed is a potential mechanism of strain reduction during running. However, if running speed is decreased the number of loading cycles will increase for a given mileage. It is unclear if these increased loading cycles are detrimental despite reductions in bone strain. The purpose of this study was to determine the effects of running speed on the probability of tibial stress fracture during a new running regimen.

METHODS

Ten male subjects ran overground at 2.5, 3.5, and 4.5m/s. Force platform and kinematic data were collected synchronously. Inverse dynamics and musculoskeletal modeling were used to determine joint contact forces acting on the distal tibia. Peak tibial contact force served as input to a finite element model to estimate tibial strains. Stress fracture probability for each running speed was determined using a probabilistic model based on published relationships of bone damage, repair, and adaptation. The effects of speed on stress fracture probability was compared using a repeated measures ANOVA.

FINDINGS

Decreasing running speed from 4.5 to 3.5m/s reduced the estimated likelihood for stress fracture by 7% (P=0.017). Decreasing running speed from 3.5 to 2.5m/s further reduced the likelihood for stress fracture by 10% (P<0.001).

INTERPRETATION

Runners wanting to reduce their risk for tibial stress fracture may benefit from a decrease in running speed. For the speeds and mileage relative to the current study, stress fracture development was more dependent on loading magnitude rather than loading exposure.

Lower extremity overuse injuries

Increased number of overuse injuries, particularly of the lower extremity, occurs in exercise. It is important for the physician who prescribes exercise to understand the mechanism of injury-repetitive microtrauma-and the risk factors for occurrence of these injuries. In the lower extremity, risk factors include inappropriate progression of the rate, intensity and duration of training; anatomic malalignment; muscle-tendon imbalances of strength, endurance, or flexibility; shoewear; surface; and pre-existent disease states. Specific recommendations for training progression, technique, and sports equipment may have to come from the physician, since the recreational athlete often does not have access to coach or athletic trainer. These are described.

Surgical and therapeutic management of a complete proximal hamstring avulsion after failed conservative approach

STUDY DESIGN

Case report.

BACKGROUND

After 2 attempts at conservative care for a diagnosis of hamstring strain, the patient had a surgical hamstring allograft reconstruction. The purpose of this report is to describe the physical therapy approach to postoperative management of a hamstring reconstruction.

CASE DESCRIPTION

A 24-year-old female coach who sustained a complete avulsion of the proximal hamstring tendon while playing softball had a surgical hamstring reconstruction using an Achilles tendon allograft. Precautions concerning range of motion and stretching, weight-bearing status, and brace were followed to protect the surgical graft. Treatment incorporated cardiovascular, strength and proprioception exercises, and progressed with the focus on correct movement patterns and eccentric muscle control during functional movements.

OUTCOMES

The patient attended 25 physical therapy sessions over 7 months. Muscle strength improved from 4/5 to 5/5. Straight-leg raise range of motion decreased from 145 degrees to 90 degrees . Lower Extremity Functional Scale (LEFS) scores improved from 15/80 to 70/80.

DISCUSSION

A complete avulsion of the proximal insertion is rare. Conservative management of hamstring tears has traditionally focused on end-range passive stretching, modalities, and direct hamstring strengthening. New evidence recommends a program that is more protective of the injured tissue and includes exercises such as core stabilization; indirect hamstring strengthening may be beneficial in the treatment of hamstring injuries. This concept was taken into account when considering the rehabilitation protocol and progression for this patient.

LEVEL OF EVIDENCE

Therapy, level 4.

Stress fractures in athletes

A stress fracture is a partial or complete bone fracture that results from repeated application of stress lower than the stress required to fracture the bone in a single loading. Otherwise healthy athletes, especially runners, sustain stress injuries or fractures. Prevention or early intervention is the preferable treatment. However, it is difficult to predict injury because runners vary with regard to biomechanical predisposition, training methods, and other factors such as diet, muscle strength, and flexibility. Stress fractures account for 0.7% to 20% of all sports medicine clinic injuries. Track-and-field athletes have the highest incidence of stress fractures compared with other athletes. Stress fractures of the tibia, metatarsals, and fibula are the most frequently reported sites. The sites of stress fractures vary from sport to sport (eg, among track athletes, stress fractures of the navicular, tibia, and metatarsal are common; in distance runners, it is the tibia and fibula; in dancers, the metatarsals). In the military, the calcaneus and metatarsals were the most commonly cited injuries, especially in new recruits, owing to the sudden increase in running and marching without adequate preparation. However, newer studies from the military show the incidence and distribution of stress fractures to be similar to those found in sports clinics. Fractures of the upper extremities are relatively rare, although most studies have focused only on lower-extremity injuries. The ulna is the upper-extremity bone injured most frequently. Imaging plays a key role in the diagnosis and management of stress injuries. Plain radiography is useful when positive, but generally has low sensitivity. Radionuclide bone scanning is highly sensitive, but lacks specificity and the ability to directly visualize fracture lines. In this article, we focus on magnetic resonance imaging, which provides highly sensitive and specific evaluation for bone marrow edema, periosteal reaction as well as detection of subtle fracture lines.

Distal tears of the hamstring muscles: review of the literature and our results of surgical treatment

BACKGROUND

Hamstring strains are among the most frequent injuries in sports, especially in events requiring sprinting and running. Distal tears of the hamstring muscles requiring surgical treatment are scarcely reported in the literature.

OBJECTIVE

To evaluate the results of surgical treatment for distal hamstring tears.

DESIGN

A case series of 18 operatively treated distal hamstring muscle tears combined with a review of previously published cases in the English literature. Retrospective study; level of evidence 4.

SETTING

Mehiläinen Sports Trauma Research Center, Mehiläinen Hospital and Sports Clinic, Turku, Finland.

PATIENTS

Between 1992 and 2005, a total of 18 athletes with a distal hamstring tear were operated at our centre.

MAIN OUTCOME MEASUREMENTS

At follow-up, the patients were asked about possible symptoms (pain, weakness, stiffness) and their return to the pre-injury level of sport.

RESULTS

The final results were rated excellent in 13 cases, good in 1 case, fair in 3 cases and poor in 1 case. 14 of the 18 patients were able to return to their former level of sport after an average of 4 months (range 2-6 months).

CONCLUSIONS

Surgical treatment seems to be beneficial in distal hamstring tears in selected cases.

Epidemiology of stress fractures

Stress fractures are a frequent cause of injury in competitive and recreational athletes. Although a number of epidemiologic studies have been conducted, the populations studied and data collection methods have varied. This article presents an overview of injury epidemiology and reviews the current body of literature regarding the occurrence of stress fractures in athletes. Given the heterogeneity of the populations studied and the variations in data collection, few broad conclusions can be drawn. There is a pressing need for large prospective studies to better establish the risks of stress fracture by sport, age, and gender.

Surgical repair of complete proximal hamstring tendon ruptures in water skiers and bull riders: a report of four cases and review of the literature

OBJECTIVE

Hamstring strains are one of the most common muscle strains in athletes; however, complete rupture of the proximal hamstring origin is rare and results from significant trauma. The objective of this paper is to present our experience of management of complete ruptures where surgical repair resulted in good results in both acute and delayed cases.

METHODS

Two water skiers and two bull riders sustained complete rupture of the proximal origin of the hamstring muscles. All underwent repair of the hamstring origin and sciatic nerve neurolysis. A post operative hamstring rehabilitation programme was instituted. Regular follow up was performed at 2, 3, 6, 9, and 12 months.

RESULTS

At a minimum final follow up of 12 months all patients had regained functional knee flexion strength with no pain and a near normal range of knee flexion. All four individuals were able to return to their previous line of work and three were able to return to their pre-injury level of sport.

CONCLUSION

Complete rupture of the hamstring origin is a potentially devastating sports injury that has implications affecting the individual's activities of daily living as well as potential as a sportsperson. Surgical repair restores the distorted anatomy, allows early functional rehabilitation, and avoids the potential debilitating neurological problem of gluteal sciatica.

A survey of flexibility training protocols and hamstring strains in professional football clubs in England

OBJECTIVES

To investigate the relation between current flexibility training protocols, including stretching, and hamstring strain rates (HSRs) in English professional football clubs.

METHOD

Questionnaire based data on flexibility training methods and HSRs were collected from 30 English professional football clubs in the four divisions during the 1998/99 season. Data were coded and analysed using cross tabulation, correlation, and multiple regression.

RESULTS

Flexibility training protocols were characterised by wide variability, with static stretching the most popular stretching technique used. Hamstring strains represented 11% of all injuries and one third of all muscle strains. About 14% of hamstring strains were reinjuries. HSRs were highest in the Premiership (13.3 (9.4)/1000 hours) with the lowest rates in Division 2 (7.8 (2.9)/1000 hours); values are mean (SD). Most (97%) hamstring strains were grade I and II, two thirds of which occurred late during training/matches. Forwards were injured most often. Use of the standard stretching protocol (SSP) was the only factor significantly related to HSR (r = -0.45, p = 0.031) in the correlation analysis, suggesting that the more SSP is used, the lower the HSR. About 80% of HSR variability was accounted for by stretching holding time (SHT), SSP, and stretching technique (STE) in the multiple regression equation: HSR = 37.79 - (0.33SHT + [corrected] 10.05SSP + 2.24STE) +/- 2.34. SHT (negatively correlated with HSR) was the single highest predictor, and accounted for 30% of HSR variability, and an additional 40% in combination with SSP.

CONCLUSIONS

Flexibility training protocols in the professional clubs were variable and appeared to depend on staffing expertise. Hamstring stretching was the most important training factor associated with HSR. The use of SSP, STE, and SHT are probably involved in a complex synergism which may reduce hamstring strains. Modification of current training patterns, especially stretching protocols, may reduce HSRs in professional footballers.

An Overview of Hip Injuries in Running

Running has steadily gained in worldwide popularity and is the primary exercise modality for many individuals of all ages. Its low cost, versatility, convenience and related health benefits appeal to men and women of broad cultural, ethnic and economic backgrounds. With more children and adults participating in recreational and competitive running, the incidence of injuries has steadily increased. Most running-related injuries affecting the lower extremities are due to preventable training errors, and some may necessitate medical evaluation or a significant reduction in training. Hip injuries in runners are due to interactions of intrinsic and extrinsic factors that adversely affect the complex regional anatomy. Acute or chronic hip pain presents a diagnostic and therapeutic challenge because the vague, nonspecific symptoms and signs may originate from local, regional or distant foci. Muscle strains and tendonitis are the most common aetiologies of hip pain and typically result from sudden acceleration/deceleration manoeuvres, direction changes or eccentric contractions. Apophysitis and avulsion fractures may affect younger runners and produce localised pain at muscle attachment sites. Iliotibial band syndrome is a common cause of lateral hip and knee symptoms characterised by sharp or burning pain that is exacerbated by activity. Bursitis, due to repetitive activity or acute trauma, may affect the trochanteric, ischial or iliopectineal bursae. Hip osteoarthritis may also produce persistent pain that worsens with running. Stress fractures are potentially serious conditions that affect women more frequently than men. Snapping hip syndrome is a benign condition that results from tight connective tissues' passing repeatedly over the greater trochanter, anterior hip capsule, lesser trochanter, femoral head or iliopectineal eminence. Acetabular labral tears, sports hernias and nerve entrapment syndromes are also potential causes of persistent hip pain in runners. Treatment of hip pain in running should focus not only on addressing the symptoms but also identifying the underlying conditions that precipitated the injury. Injury prevention and comprehensive rehabilitation are essential, since prior hip injuries increase the risk of subsequent ones. Coaches, trainers and medical personal who care for runners should advocate running regimens, surfaces, shoes, technique and individualised conditioning programmes that minimise the risk of initial or recurrent hip injuries.

Stress injuries to bone in college athletes: a retrospective review of experience at a single institution

BACKGROUND

No comprehensive studies have been published on stress injuries to bone in college athletes.

PURPOSE

To review, in a college athlete population, the epidemiologic aspects of stress injuries to bone, and to examine a subset of patients who were treated with a uniform protocol for return to activities, with magnetic resonance imaging as the primary tool for diagnosis.

STUDY TYPE

Retrospective review.

METHODS

Ten years of medical records from a Division I college institution were reviewed. Location and grade of stress injury to bone and duration of disability were recorded. All injured athletes followed the same treatment program, with the exception of football players, who were excluded from the return to sport analyses.

RESULTS

Seventy-four athletes had lower extremity symptoms consistent with stress injury to bone. Diagnosis was confirmed in 68 of these athletes, 61 via magnetic resonance imaging, 6 via positive radiographs only, and 1 via bone scan only. Distance runners accounted for the most stress injuries to bone for both men and women. The tibia (37%) was the most frequently involved bone; however, as an anatomic region, the foot (44%) was the site of the most stress injuries. There was a significant correlation between grade of injury and time to full return to activity.

CONCLUSIONS

The grading system used at this institution is a standardized tool that can be used to predict time to return to sport. A standardized rehabilitation protocol allowed for an appropriate plan to return the athletes to pain-free competition.

Stress fractures in athletes: review of 196 cases

The purpose of this study was to investigate the association of stress fractures with age, sex, sport level, sporting activity, and skeletal site in athletes seen at our sports medicine clinic between September 1991 and May 2001. During these 10 years, 10 726 patients (6415 males, 3861 females) visited our clinic because of sport-related injuries, and 196 patients [125 males (1.9%), 71 females (1.8%)] sustained stress fractures. The average age of the patients with stress fractures was 20.1 years (range 10-46 years); 84 patients (42.6%) were 15-19 years of age, and 68 (34.7%) were 20-24 years of age. Altogether, 74 patients (37.8%) were active at the high recreational level and 122 (62.2%) at the competitive level. The sites of the stress fractures varied from sport to sport. The ulnar olecranon was the most common stress fracture site among baseball athletes and the rib among the rowing athletes. Classical ballet, aerobics, tennis, and volleyball athletes predominantly sustained stress fractures of the tibial shaft. Basketball athletes predominantly sustained stress fractures of the tibial shaft and medial malleolus and the metatarsal bone, whereas track and field and soccer athletes predominantly sustained stress fractures of the tibial shaft and pubic bone. Our results show that stress fractures are seen even in high-level adolescent athletes, with similar proportions for males and females, and that particular sports are associated with specific sites for stress fractures.

Are overground or treadmill runners more likely to sustain tibial stress fracture?

BACKGROUND

Repetitive high bone strain and/or strain rates, such as those that occur during running, contribute to stress fractures as well as promoting maintenance of or increase in bone mass. Kinematic differences are known to exist between overground and treadmill running and these may be reflected in different bone strains and strain rates during the two running techniques.

AIM

To measure in vivo strains and strain rates in human tibia during treadmill and overground running and determine if there are significant differences in strain and strain rate levels between the two running techniques.

METHODS

A strain gauged bone staple was mounted percutaneously along the axial direction in the mid diaphysis of the medial tibia in three subjects, and in vivo tibial strains were measured during treadmill and overground running at 11 km/h.

RESULTS

Axial compression strains (p<0.0001), tension strains (p<0.001), compression strain rates (p<0.0001), and tension strain rates (p<0.0001) were 48-285% higher during overground running than during treadmill running.

CONCLUSIONS

On the basis of lower in vivo strains and strain rates, treadmill runners are at lower risk of developing tibial stress fractures, but less likely to achieve tibial bone strengthening, than overground runners.

The role of biomechanical shoe orthoses in tibial stress fracture prevention

BACKGROUND

Biomechanical orthoses have been shown to lower stress fracture incidence in infantry recruits. However, these results may not be applicable to running athletes.

HYPOTHESIS

Training in either running shoes or military boots with custom biomechanical shoe orthoses lessens tibial bone strains and strain rates during walking and running.

STUDY DESIGN

Randomized controlled laboratory study.

METHODS

In vivo strain measurements were made in nine subjects to determine whether the use of biomechanical orthoses lowers tibial strains during both walking and running and whether such lowering depends on the type of shoe worn. Measurements were made during treadmill walking at 5 km/hr and then during serial 2-km treadmill runs at 13 km/hr with running shoes, with and without the orthoses, and during serial 1-km runs with army boots, with and without the orthoses.

RESULTS

When soft or semirigid biomechanical orthoses were worn with boots, the tibial peak-to-peak strains were significantly lowered. Soft orthoses also significantly lowered the tension and compression strain rates when worn with boots. During running, semirigid orthoses significantly increased the compression and tension strain rates when worn with boots.

CONCLUSIONS

The use of biomechanical orthoses may be warranted for tibial stress fracture prevention during training in which boots are worn and that mostly involves walking, but they are not warranted for activities that primarily involve running or are performed in running shoes.

Chronic Achilles tendinosis: recommendations for treatment and prevention

Chronic Achilles tendinosis is a condition with an unknown aetiology and pathogenesis that is often, but not always, associated with pain during loading of the Achilles tendon. Histologically, there are no inflammatory cells, but increased amounts of interfibrillar glycosaminoglycans and changes in the collagen fibre structure and arrangement are seen. In situ microdialysis has confirmed the absence of inflammation. It is a condition that is most often seen among recreational male runners aged between 35 and 45 years, and it is most often considered to be associated with overuse. However, this condition is also seen in patients with a sedentary lifestyle. Chronic Achilles tendinosis is considered a troublesome injury to treat. Nonsurgical treatment most often includes a combination of rest, NSAIDs, correction of malalignments, and stretching and strengthening exercises, but there is sparse scientific evidence supporting the use of most proposed treatment regimens. It has been stated that, in general, nonsurgical treatment is not successful and surgical treatment is required in about 25% of patients. However, in a recent prospective study, treatment with heavy load eccentric calf muscle training showed very promising results and may possibly reduce the need for surgical treatment of tendinosis located in the midportion of the Achilles tendon. The short term results after surgical treatment are frequently very good, but in the few studies with long term follow-up there are signs of a possible deterioration with time. Calf muscle strength takes a long time to recover and, furthermore, a prolonged progressive calcaneal bone loss has been shown on the operated side up to 1 year after surgical treatment.

Passive knee extension test to measure hamstring muscle tightness

The purpose of this study was twofold: (a) to examine the reliability of a test designed to measure tightness of the hamstring muscles, and (b) to assess the pelvic motion during this test. The knee was passively extended by a standardized force, while the hip was stabilized in 120 degrees of flexion. The knee angle was measured with a goniometer and represents the hamstring tightness. Twenty-eight test-retests were performed. The correlation coefficient was found to be 0.99, and the CV was found to be 1%. We used a MacReflex measurement system to assess the associated pelvic motion. Eight measurements were taken, and the median of associated pelvic motion was 4.1 degrees. It is concluded that the passive knee extension test is a simple and reliable method, and the associated pelvic motion is minimal.

Epidemiology and site specificity of stress fractures

Clinically, stress fractures appear to be a common overuse injury among athletes and in military recruits undertaking basic training; however, there is a lack of sound epidemiologic studies describing stress fracture occurrence in athletes. Few have directly compared stress fracture rates between sports to establish which poses the greatest risk for this injury. Furthermore, incidence rates, expressed in terms of exposure, have rarely been reported for stress fractures in athletes. Nevertheless, available data suggest that runners and ballet dancers are at relatively high risk for stress fractures. Although a gender difference in rates is clearly evident in military populations, this is less apparent in athletes. Other participant characteristics, such as age and race, may also influence stress fracture risk. The most common site of stress fracture in athletes is the tibia, although the site reflects the nature of the load applied to the skeleton. Stress fracture morbidity, expressed as the time until return to sport or activity, varies depending on the site. Generally, a period of 6 to 8 weeks is needed for healing; however, stress fractures at certain sites, such as the navicular and anterior tibial cortex, are often associated with protracted recovery and, in some cases, termination of sporting pursuits.

The incidence and distribution of stress fractures in competitive track and field athletes. A twelve-month prospective study

The incidence and distribution of stress fractures were evaluated prospectively over 12 months in 53 female and 58 male competitive track and field athletes (age range, 17 to 26 years). Twenty athletes sustained 26 stress fractures for an overall incidence rate of 21.1%. The incidence was 0.70 for the number of stress fractures per 1000 hours of training. No differences were observed between male and female rates (P > 0.05). Twenty-six stress fractures composed 20% of the 130 musculoskeletal injuries sustained during the study. Although there was no difference in stress fracture incidence among athletes competing in different events (P > 0.05), sprints, hurdles, and jumps were associated with a significantly greater number of foot fractures; middle- and long-distance running were associated with a greater number of long bone and pelvic fractures (P < 0.05). Overall, the most common sites of bone injuries were the tibia with 12 injuries (46%), followed by the navicular with 4 injuries (15%), and the fibula with 3 injuries (12%). The high incidence of stress fractures in our study suggests that risk factors in track and field athletes should be identified.

Achilles tendon injuries in athletes

Two-thirds of Achilles tendon injuries in competitive athletes are paratenonitis and one-fifth are insertional complaints (bursitis and insertion tendinitis). The remaining afflictions consist of pain syndromes of the myotendineal junction and tendinopathies. The majority of Achilles tendon injuries from sport occur in males, mainly because of their higher rates of participation in sport, but also with tendinopathies a gender difference is probably indicated. Athletes in running sports have a high incidence of Achilles tendon overuse injuries. About 75% of total and the majority of partial tendon ruptures are related to sports activities usually involving abrupt repetitive jumping and sprinting movements. Mechanical factors and a sedentary lifestyle play a role in the pathology of these injuries. Achilles tendon overuse injuries occur at a higher rate in older athletes than most other typical overuse injuries. Recreational athletes with a complete Achilles tendon rupture are about 15 years younger than those with other spontaneous tendon ruptures. Following surgery, about 70 to 90% of athletes have a successful comeback after Achilles tendon injury. Surgery is required in about 25% of athletes with Achilles tendon overuse injuries and the frequency of surgery increases with patient age and duration of symptoms as well as occurrence of tendinopathic changes. However, about 20% of injured athletes require a re-operation for Achilles tendon overuse injuries, and about 3 to 5% are compelled to abandon their sports career because of these injuries. Myotendineal junction pain should be treated conservatively. Partial Achilles tendon ruptures are primarily treated conservatively, although the best treatment method of chronic partial rupture seems to be surgery. Complete Achilles tendon ruptures of athletes are treated surgically, because this increases the likelihood of athletes reaching preinjury activity levels and minimises the risk of re-ruptures. Marked forefoot varus is found in athletes with Achilles tendon overuse injuries, reflecting the predisposing role of ankle joint overpronation. Athletes with the major stress in lower extremities have often a limited range of motion in the passive dorsiflexion of the ankle joint and total subtalar joint mobility, which seems to be predisposing factor for these injuries. Various predisposing transient factors are found in about one-third of athletes with Achilles tendon overuse injuries; of these, traumatic factors (mostly minor injuries) predominate. The typical histological features of chronically inflamed paratendineal tissue of the Achilles tendon are profound proliferation of loose, immature connective tissue and marked obliterative and degenerative alterations in the blood vessels. These changes cause continuing leakage of plasma proteins, which may have an important role in the pathophysiology of these injuries. The chronically inflamed paratendineal tissues of the Achilles tendon do not seem to have enough capacity to form mature connective tissue.

Reliability of an Active-Knee-Extension Test for Determining Hamstring Muscle Flexibility

This study examined the intratester and intertester reliability of an active-knee-extension test (AKET) for determining hamstring muscle length (flexibility). Three testers performed repeated AKET measurements on 22 subjects. Intraclass correlation coefficients (ICC were used to calculate intratester and intertester reliability. Also, standard error of measurements (SEM) were calculated. The ICC and SEM were .96 and 1.82°, respectively, for Tester 1, .99 and 1.75° for Tester 2, and .99 and 1.80° for Tester 3. Intratester 95% confidence intervals ranged from 60.54 to 69.82°. Intertester ICC and SEM for two testers were .93 and 4.81°, respectively. A 95% intertester confidence interval ranged from 56.35 to 75.21 °; this reveals that intertester AKET values contained more error and suggests that only intratester AKET values should be used when comparing hamstring flexibility values. The AKET may provide a more accurate method for determining hamstring flexibility and quantifying changes that occur as a result of injury and stretching procedures.

Hamstring muscle injury: the influence of strength, flexibility, warm-up, and fatigue

Hamstring muscle injury is a complex problem for athletes, physicians, physical therapists, and athletic trainers. This injury tends to recur and to limit participation in athletic competition. The etiology of hamstring muscle injury continues to be confusing and incomplete for clinicians and researchers. The purposes of this paper are: 1) to review briefly hamstring muscle group anatomy and function, 2) to review the clinical and animal research literature concerning the role of strength, flexibility, warm-up, and fatigue in hamstring muscle injury, 3) to present an evaluation and rehabilitation scheme for hamstring muscle injury, 4) to describe a theoretical multiple factor hamstring injury model, and 5) to offer recommendations concerning prevention of hamstring muscle injury. During preseason screening and rehabilitation following hamstring muscle injury, clinicians should consider the influence of hamstring strength, flexibility, warm-up, and fatigue on muscle performance. Additional research concerning these factors is recommended. J Orthop Sports Phys Ther 1992;16(1):12-18.

Stress fractures of the hip in Royal Marine recruits under training: a retrospective analysis

At the Commando Training Centre, Royal Marines (CTCRM), a retrospective analysis of the occurrence of one form of stress fracture--that of the hip--has shown that this fracture is a significant cause of morbidity in the recruits. Most fractures presented in the last few weeks of training, which may reflect the increasing workload that the training involves. Two different fracture sites are identified, but there is no discernible difference in presentation or outcome between them. The condition may be easily misdiagnosed as a more trivial injury. A careful history and examination, and a low threshold for radiographic and scintigraphic investigation are important for diagnosis, and to avoid the catastrophic failure of the fracture seen in one of our patients.

Achilles paratendonitis: an evaluation of steroid injection

A prospective, randomised, double-blind study of 28 patients presenting with Achilles paratendonitis was undertaken in order to evaluate the role of peritendonous injection of methy prednisolone acetate (Depo Medrone). At presentation patients were either administered peri-tendonous injection of 40 mgs of methyl prednisolone acetate suspended in 1 ml of 0.25% marcaine or 2 ml of 0.25% marcaine alone. Response was gauged by resolution of pain, tenderness and return to normal activity. Patients who failed to respond to initial treatment were crossed over to the other group at 12 weeks. All patients received standardised physiotherapy. Results indicate that peri-tendonous injection of methyl prednisolone acetate is of no value in Achilles paratendonitis.

Stress fractures in athletes. A study of 320 cases

We analyzed cases of 320 athletes with bone scan-positive stress fractures (M = 145, F = 175) seen over 3.5 years and assessed the results of conservative management. The most common bone injured was the tibia (49.1%), followed by the tarsals (25.3%), metatarsals (8.8%), femur (7.2%), fibula (6.6%), pelvis (1.6%), sesamoids (0.9%), and spine (0.6%). Stress fractures were bilateral in 16.6% of cases. A significant age difference among the sites was found, with femoral and tarsal stress fractures occurring in the oldest, and fibular and tibial stress fractures in the youngest. Running was the most common sport at the time of injury but there was no significant difference in weekly running mileage and affected sites. A history of trauma was significantly more common in the tarsal bones. The average time to diagnosis was 13.4 weeks (range, 1 to 78) and the average time to recovery was 12.8 weeks (range, 2 to 96). Tarsal stress fractures took the longest time to diagnose and recover. Varus alignment was found frequently, but there was no significant difference among the fracture sites, and varus alignment did not affect time to diagnosis or recovery. Radiographs were taken in 43.4% of cases at the time of presentation but were abnormal in only 9.8%. A group of bone scan-positive stress fractures of the tibia, fibula, and metatarsals (N = 206) was compared to a group of clinically diagnosed stress fractures of the same bone groups (N = 180), and no significant differences were found. Patterns of stress fractures in athletes are different from those found in military recruits. Using bone scan for diagnosis indicates that tarsal stress fractures are much more common than previously realized. Time to diagnosis and recovery is site-dependent. Technetium99 bone scan is the single most useful diagnostic aid. Conservative treatment of stress fractures in athletes is satisfactory in the majority of cases.

Injuries in elite orienteers

A prospective study of injuries in 89 elite orienteers showed a total incidence of three injuries per 1,000 training hours, with no difference between the sexes. Mean absence from training per year due to injury was 20 days for men and 19 days for women. Most injuries (80.3%) occurred during training, while the remaining injuries occurred during competition. The lower extremities were affected in 93.6% of the male injuries and in all of the female injuries. The majority of injuries (60.6%) were moderate, while 19.7% were minor and 19.7% were major injuries. Overuse injuries accounted for 57%; 43% of the injuries were due to trauma. Overuse injuries predominated in the preseason period, while the incidence was equal between overuse and traumatic injuries over the rest of the year. Of a total number of 38 overuse injuries, 60.5% occurred during running on tracks or roads. Thirteen injuries (19.7%) were major; the majority (84.6%) of these injuries were due to overuse, affecting the knee in eight cases (61.5%). Of the major injuries, 76.5% occurred during the period December to May. Of a total number of 28 traumatic injuries, 78.6% occurred while running on uneven ground, mainly in forests. Among the traumatic injuries, ankle sprains accounted for 57.1%, equally distributed between the sexes. The majority of these sprains (81.2%) were moderate. This paper will discuss injury mechanisms and possibilities of prevention.