Incidence and prevalence of lumbar stress fracture in English County Cricket fast bowlers, association with bowling workload and seasonal variation

Lumbar Bone Stress Injuries and Nonunited Defects in Elite Australian Cricket Players

OBJECTIVE

To describe the presentation and management of lumbar bone stress injuries (LBSI), recurrent LBSI, and lumbar nonunited defects in elite Australian male and female cricket players.

DESIGN

Retrospective case series.

SETTING

Professional domestic and international cricket teams over 13 seasons.

PARTICIPANTS

Elite Australian cricket players.

INDEPENDENT VARIABLES

Symptomatic LBSI requiring time off cricket and lumbar nonunited defects, both confirmed by imaging.

MAIN OUTCOME MEASURES

Incidence, presentation, history, healing, and management.

RESULTS

211 LBSI were identified at an average incidence of 5.4 per 100 players per season. LBSI were most common in male pace bowlers younger than 20 years of age (58.1 per 100 players per season), however, were also observed in older players, females, and non-pace bowlers. Recurrent LBSI accounted for 33% (27%-40%) of all LBSI. Median days to return to match availability was 182 (128-251) days for all LBSI, with a shorter time frame observed for new and less severe injuries, and male spin bowlers. Healing was demonstrated in 87% (81%-91%) of all LBSI cases. 29 nonunited defects were identified and predisposed subsequent pain, LBSI, and spondylolisthesis.

CONCLUSIONS

LBSI are experienced by approximately 5.4 in every 100 elite Australian cricket players per season, with a high time cost of approximately 4 to 8 months. Nonunited defects also have a high time cost with associated subsequent lumbar spine issues. The findings of this study reinforce the importance of early detection and conservative management of LBSI, particularly for younger male pace bowlers and players with recurrent LBSI, which may be supported by MRI.

Intrinsic variables associated with low back pain and lumbar spine injury in fast bowlers in cricket: a systematic review

BACKGROUND

Lumbar spine injuries in fast bowlers account for the greatest missed playing time in cricket. A range of extrinsic and intrinsic variables are hypothesised to be associated with low back pain and lumbar spine injury in fast bowlers, and an improved understanding of intrinsic variables is necessary as these may alter load tolerance and injury risk associated with fast bowling. This review critically evaluated studies reporting intrinsic variables associated with low back pain and lumbar spine injury in fast bowlers and identified areas for future investigation.

METHODS

OVID Medline, EMBASE, SPORTDiscus, CINAHL, Web of Science and SCOPUS databases were last searched on 3 June 2022 to identify studies investigating intrinsic variables associated with low back pain and lumbar spine injury in cricket fast bowlers. Terms relevant to cricket fast bowling, and intrinsic variables associated with lumbar spine injury and low back pain in fast bowlers were searched. 1,503 abstracts were screened, and 118 full-text articles were appraised to determine whether they met inclusion criteria. Two authors independently screened search results and assessed risk of bias using a modified version of the Quality in Prognostic Studies tool.

RESULTS

Twenty-five studies met the inclusion criteria. Overall, no included studies demonstrated a low risk of bias, two studies were identified as moderate risk, and twenty-three studies were identified as high risk. Conflicting results were reported amongst studies investigating associations of fast bowling kinematics and kinetics, trunk and lumbar anatomical features, anthropometric traits, age, and neuromuscular characteristics with low back pain and lumbar spine injury.

CONCLUSION

Inconsistencies in results may be related to differences in study design, injury definitions, participant characteristics, measurement parameters, and statistical analyses. Low back pain and lumbar spine injury occurrence in fast bowlers remain high, and this may be due to an absence of low bias studies that have informed recommendations for their prevention. Future research should employ clearly defined injury outcomes, analyse continuous datasets, utilise models that better represent lumbar kinematics and kinetics during fast bowling, and better quantify previous injury, lumbar anatomical features and lumbar maturation.

TRIAL REGISTRATION

Open Science Framework https://doi.org/10.17605/OSF.IO/ERKZ2 .

Is MRI screening for bone marrow oedema useful in predicting lumbar bone stress injuries in adult male professional cricketers? A New Zealand pilot study

OBJECTIVES

The aims were to (1) prospectively observe the incidence of bone marrow oedema in asymptomatic adult male domestic professional cricketers during a season and evaluate its relationship to the development of lumbar bone stress injury and (2) further understand the practicalities of implementing a Magnetic Resonance Imaging-based screening program to prevent lumbar bone stress injury in New Zealand cricket.

DESIGN

Prospective observational cohort.

METHODS

Adult male pace bowlers received 6-weekly pre-planned Magnetic Resonance Imaging scans over a single season to determine the presence and intensity of bone marrow oedema in the posterior vertebral arches of the lumbar spine. The participants bowling volume and back pain levels were monitored prospectively.

RESULTS

22 participants (mean age 25.3 years (range 20-32 years)) completed all 4 scans. Ten participants had a prior history of lumbar bone stress injury. Ten participants (45 %, 95 % confidence interval 24-68 %) had bone marrow oedema evident on at least one scan, with 9 (41 %) participants recording a bone marrow oedema intensity ≥ 2 and 5 (23 %) participants demonstrated an intensity ≥ 3. During the study one participant was diagnosed with a lumbar bone stress reaction. No participants developed a lumbar bone stress fracture.

CONCLUSIONS

Due to the lower incidence of lumbar bone stress injuries in adult bowlers coupled with uncertainty over appropriate threshold values for bone marrow oedema intensity, implementation of a resource intense screening program aimed at identifying adult domestic cricketers at risk of developing a lumbar bone stress injury is not currently supported.

Lumbar spine bone mineral adaptation: cricket fast bowlers versus controls

Elite adult male fast bowlers have high lumbar spine bone mineral, particularly on the contralateral side to their bowling arm. It is thought that bone possesses its greatest ability to adapt to loading during adolescence, but it is unknown at what age the greatest changes in lumbar bone mineral and asymmetry develops in fast bowlers.

Objectives

This study aims to evaluate the adaptation of the lumbar vertebrae in fast bowlers compared to controls and how this is associated with age.

Methods

91 male fast bowlers and 84 male controls aged 14-24 years had between one and three annual anterior-posterior lumbar spine dual-energy-X-ray absorptiometry scans. Total (L1-L4) and regional ipsilateral and contralateral L3 and L4 (respective to bowling arm) bone mineral density and content (BMD/C) were derived. Multilevel models examined the differences in lumbar bone mineral trajectories between fast bowlers and controls.

Results

At L1-L4 BMC and BMD, and contralateral BMD sites, fast bowlers demonstrated a greater negative quadratic pattern to their accrual trajectories than controls. Fast bowlers had greater increases in BMC in L1-L4 between 14 and 24 years of 55% compared with controls (41%). Within vertebra, asymmetry was evident in all fast bowlers and increased by up to 13% in favour of the contralateral side.

Conclusions

Lumbar vertebral adaptation to fast bowling substantially increased with age, particularly on the contralateral side. The greatest accrual was during late adolescence and early adulthood, which may correspond with the increasing physiological demands of adult professional sport.

Activity specific areal bone mineral density is reduced in athletes with stress fracture and requires profound recovery time: A study of lumbar stress fracture in elite cricket fast bowlers

OBJECTIVES

The aims of this study were to determine whether lumbar areal bone mineral density differed between cricket fast bowlers with and without lumbar stress fracture, and whether bone mineral density trajectories differed between groups during rehabilitation.

DESIGN

Cross-sectional and cohort.

METHODS

29 elite male fast bowlers received a post-season anteroposterior lumbar dual-energy X-ray absorptiometry scan and a lumbar magnetic resonance imaging scan to determine stress fracture status. Participants were invited for three additional scans across the 59 weeks post baseline or diagnosis of injury. Bone mineral density was measured at L1 - L4 and ipsilateral and contralateral L3 and L4 sites. Independent-sample t-tests determined baseline differences in bone mineral density and multilevel models were used to examine differences in bone mineral density trajectories over time between injured and uninjured participants.

RESULTS

17 participants with lumbar stress fracture had lower baseline bone mineral density at L1 - L4 (7.6 %, p = 0.034) and contralateral sites (8.8-10.4 %, p = 0.038-0.058) than uninjured participants. Bone mineral density at all sites decreased 1.9-3.0 % by 20-24 weeks before increasing to above baseline levels by 52 weeks post injury.

CONCLUSIONS

Injured fast bowlers had lower lumbar bone mineral density at diagnosis that decreased following injury and did not return to baseline until up to a year post-diagnosis. Localised maladaptation of bone mineral density may contribute to lumbar stress fracture. Bone mineral density loss following injury may increase risk of recurrence, therefore fast bowlers require careful management when returning to play.

Is Increased Kicking Leg Iliopsoas Muscle Tightness a Predictive Factor for Developing Spondylolysis in Adolescent Male Soccer Players?

OBJECTIVE

To identify predictive risk factors of lumbar stress (LS) fracture developing from an asymptomatic stress reaction of the pedicle among adolescent male soccer players.

DESIGN

Prospective cohort study.

SETTING

Amateur Japanese adolescent male soccer team.

PARTICIPANTS

Japanese adolescent male soccer players (n = 195) aged 12 to 13 years.

ASSESSMENT OF RISK FACTORS INDEPENDENT VARIABLES

Height, body weight, body mass index, muscle tightness of both lower extremities (iliopsoas, hamstrings, and quadriceps), lumbar bone mineral content, developmental age, and lumbar lordosis angle were measured as baseline measurements.

MAIN OUTCOME MEASURES DEPENDENT VARIABLE

Players who were diagnosed with an asymptomatic stress reaction of the lumbar spine pedicle at baseline were followed; extension-based lumbar pain was defined 1 year after the baseline. The players were assigned to the LS fracture or control (CON) group at follow-up.

RESULTS

At baseline, 40 boys were diagnosed with an asymptomatic stress reaction of the lumbar spine pedicle. The difference in muscle tightness between the kicking leg and supporting leg was significantly different (P = 0.012) between the LS (n = 16) and CON (n = 22) groups. Increase in iliopsoas muscle tightness in the kicking leg was a predictive risk factor of developing extension-based lumbar pain after adjusting for developmental age and body mass index (odds ratio, 1.54; 95% confidence interval, 1.05-2.27).

CONCLUSIONS

Development of extension-based lumbar pain from an asymptomatic stress reaction of the pedicle among adolescent male soccer players was associated with increased iliopsoas muscle tightness of the kicking leg relative to that of the supporting leg.

External workload intensity in cricket fast bowlers across maximal and submaximal intensities: Modifying PlayerLoad and IMU location

Workload is a commonly accepted risk factor for injury among fast bowlers, however many methods exist to characterise workload. Recently, automated intensity-sensitive measures like PlayerLoad have been used to improve the estimation of workload in fast bowlers. The purpose of this study was to determine whether similar variables could be extracted from a single inertial measurement unit (IMU) that highly correlate with intensity, according to release speed. Eight elite and pre-elite bowlers participated in the study, with each bowler bowling one over each at 60%, 80% and 100% intensity and repeating this across two sessions (36 balls per participant). IMUs were placed on the upper-back and non-bowling wrist and maximum PlayerLoad from each delivery (PL_max) was compared to the accumulated value across each delivery (PL_acc). The strongest correlation with release speed was with PL_acc from the non-bowling wrist (R = 0.74), followed by PL_acc from the upper-back (R = 0.65) and PL_max from the upper back (R = 0.60). Consequently, an improved estimation of the intensity at which bowlers are working at could be gained by examining accumulated PlayerLoad values from an IMU on the non-bowling wrist.

Surgical repair of lumbar stress fractures in professional cricketers

Background

Professional cricket fast bowlers sustain high rates of lumbar stress fractures (spondylolysis). Limited research exists around the success of surgical repair when these injuries fail conservative treatment. We present an ambispective cohort study of spondylolysis surgical repair in a consecutive group of multi-national professional cricket fast bowler using a technique not previously reported in this unique sporting group.

Methods

Between 2004 and 2019, a consecutive series of male professional fast bowlers with lumbar spondylolysis who had repeatedly failed conservative treatment and subsequently received surgical repair using a cable-screw construct were reviewed. Analysis comprised of ambispective outcome and radiological data collection and a survey at final follow-up.

Results

The cohort included 13 elite (7 state and 6 international) cricket fast bowlers from 3 countries (New Zealand, Australian and India) with an average age of 26 years (range, 20.3-29.5 years). All returned to play professional cricket at a median time of 8 months (IQR, 7-11 months) post surgery. All ten players surveyed at final follow-up [median, 38 (IQR, 31-103) months, range, 15-197 months] rated their bowling performance as the 'same or better' compared with prior to surgery. At final follow-up, 10 players continue to play cricket professionally ranging from 15 to 107 months post-surgery [median 35 (IQR, 24-43) months].

Conclusions

Our cohort demonstrated favorable return to play rates and career longevity following surgical repair of spondylolysis. To our knowledge it is the largest published surgical series of spondylolysis repair in cricketers, and the first to document the success of a cable-screw surgical technique in this sporting group.

The relationship between cricket participation, health and wellbeing: A scoping review

Summarising and synthesising the evidence on cricket health and wellbeing can help inform cricket stakeholders and navigate future research directions. The purpose of this study was to investigate the relationship between cricket participation, health and wellbeing at all ages and playing standards, and identify research gaps in the existing literature. A scoping review was performed from inception to March, 2020. Studies were included if they assessed a construct related to health and/or wellbeing in cricketers, available in English. 219 articles were eligible. Injury incidence per 1,000 player exposures ranged from 1.8-5.7 injuries. 48% of former cricketers experienced persistent joint pain. However, former cricketers reported greater physical activity levels and mental-components of quality of life compared to the general population. Heat injury/illness and skin cancer are concerns and require further research. Cricket participation is associated with an inherent injury risk, which may have negative implications for musculoskeletal health in later life. However, cricket participation is associated with high quality of life which can persist after retirement. Gaps in the literature include prospective studies on health and wellbeing of cricketers, female cricketers, injury prevention strategies, and the impact of cricket participation on metabolic health and lifetime physical activity.

Lumbar Bone Mineral Adaptation: The Effect of Fast Bowling Technique in Adolescent Cricketers

INTRODUCTION

Localised bone mineral density (BMD) adaptation of the lumbar spine, particularly on the contralateral side to the bowling arm, has been observed in elite male cricket fast bowlers. No study has investigated this in adolescents, or the role of fast bowling technique on lumbar BMD adaptation. This study aims to investigate lumbar BMD adaptation in adolescent cricket fast bowlers, and its relationship with fast bowling technique.

METHODS

39 adolescent fast bowlers underwent antero-posterior DXA scan of their lumbar spine. Hip, lumbopelvic and thoracolumbar joint kinematics, and vertical ground reaction kinetics were determined using 3D motion capture and force plates. Significant partial (covariate: fat free mass) and bivariate correlations of the technique parameters with whole lumbar (L1-L4) BMD and BMD asymmetry (L3 and L4) were advanced as candidate variables for multiple stepwise linear regression.

RESULTS

Adolescent fast bowlers demonstrated high lumbar Z-Scores (+1.0; 95%CI: 0.7 - 1.4) and significantly greater BMD on the contralateral side of L3 (9.0%; 95%CI: 5.8 - 12.1%) and L4 (8.2%; 95%CI: 4.9 - 11.5%). Maximum contralateral thoracolumbar rotation and maximum ipsilateral lumbopelvic rotation in the period between back foot contact (BFC) and ball release (BR), as well as contralateral pelvic drop at front foot contact (FFC), were identified as predictors of L1-L4 BMD, explaining 65% of the variation. Maximum ipsilateral lumbopelvic rotation between BFC and BR, as well as ipsilateral lumbopelvic rotation and contralateral thoracolumbar side flexion at BR, were predictors of lumbar asymmetry within L3 and L4.

CONCLUSION

Thoracolumbar and lumbopelvic motion are implicated in the aetiology of the unique lumbar bone adaptation observed in fast bowlers whereas vertical ground reaction force, independent of body mass, was not. This may further implicate the osteogenic potential of torsional rather than impact loading in exercise-induced adaptation.

The impact of COVID-19 related disruption on injury rates in elite men's domestic cricket

This study aimed to investigate the impact of COVID-19 enforced prolonged training disruption and shortened competitive season, on in-season injury and illness rates. Injury incidence and percent proportion was calculated for the 2020 elite senior men's domestic cricket season and compared to a historical average from five previous regular seasons (2015 to 2019 inclusive). The injury profile for the shortened 2020 season was generally equivalent to what would be expected in a regular season, except for a significant increase in medical illness as a proportion of time loss (17% compared to historic average of 6%) and in-season days lost (9% compared to historic average of 3%) due to COVID-19 related instances (most notably precautionary isolation due to contact with a confirmed or suspected COVID-19 case). There was a significant increase in the proportion of in-season days lost to thigh injuries (24% compared to 9%) and a significant decrease in the proportion of days lost to hand (4% compared to 12%) and lumbar spine (7% compared to 21%) injuries. These findings enhance understanding of the impact prolonged period of training disruption and shortened season can have on cricket injuries and the challenges faced by practitioners under such circumstances.

Quantification of the demands of cricket bowling and the relationship to injury risk: a systematic review

BACKGROUND

Bowling in cricket is a complex sporting movement which, despite being well characterised, still produces a significant number of injuries each year. Fast bowlers are more likely to be injured than any other playing role. Frequency, duration, intensity and volume of bowling, which have been generalised as measurements of workload, are thought to be risk factors for injuries. Injury rates of fast bowlers have not reduced in recent years despite the implementation of various workload monitoring practices.

OBJECTIVE

To identify the variables used to quantify frequency, intensity, time and volume of bowling; and evaluate relationships between these variables and injury risk.

METHODS

Six online databases were systematically searched for studies on fast bowling that included terms related to workload. Population characteristics, variables relating to demand and their relationship to standardised definitions of physical activity were extracted from all included studies.

RESULTS

Bowling workload is typically quantified through measures of frequency, duration, or indirect intensity, with few studies reporting on bowling volume.

CONCLUSIONS

When reported on, volume was often described using imprecise or insufficient measures of intensity. There is a need to develop more appropriate measures of intensity during bowling and improve the quality of evidence to inform on bowling programme management practices.

Cricket Fast Bowling Technique and Lumbar Bone Stress Injury

INTRODUCTION

Lumbar bone stress injuries (LBSI) are the most prevalent injury in cricket. Although fast bowling technique has been implicated in the etiology of LBSI, no previous study has attempted to prospectively analyze fast bowling technique and its relationship to LBSI. The aim of this study was to explore technique differences between elite cricket fast bowlers with and without subsequent LBSI.

METHODS

Kinematic and kinetic technique parameters previously associated with LBSI were determined for 50 elite male fast bowlers. Group means were compared using independent-samples t-tests to identify differences between bowlers with and without a prospective LBSI. Significant parameters were advanced as candidate variables for a binary logistic regression analysis.

RESULTS

Of the 50 bowlers, 39 sustained a prospective LBSI. Significant differences were found between injured and noninjured bowlers in rear knee angle, rear hip angle, thoracolumbar side flexion angle, and thoracolumbar rotation angle at back foot contact; the front hip angle, pelvic tilt orientation, and lumbopelvic angle at front foot contact; and the thoracolumbar side flexion angle at ball release and the maximal front hip angle and ipsilateral pelvic drop orientation. A binary logistic model, consisting of rear hip angle at back foot contact and lumbopelvic angle at front foot contact, correctly predicted 88% of fast bowlers according to injury history and significantly increased the odds of sustaining an LBSI (odds ratio, 0.88 and 1.25, respectively).

CONCLUSIONS

Lumbopelvic motion is implicated in the etiology of LBSI in fast bowling, with inadequate lumbopelvifemoral complex control as a potential cause. This research will aid the identification of fast bowlers at risk of LBSI, as well as enhancing coaching and rehabilitation of fast bowlers from LBSI.

Narrative review of mental illness in cricket with recommendations for mental health support

Introduction

Epidemiology reporting within the cricketing medical literature has emerged over the past 2 years, with a focus on physical injuries. Despite mental health in elite sport gaining increasing recognition, few studies have addressed mental health symptoms and disorders within cricket. Recently, cricketers have been prominent in the mainstream media describing their lived experiences of mental illness. As a result, some have withdrawn from competition and suggested there is an unmet need for mental health services within the sport.

Objectives

(i) To appraise the existing evidence on mental health symptoms and disorders amongst cricketers. (ii) To provide guidance on shaping mental health research and services within cricket.

Design

A narrative review of the literature from inception of available databases until 26 July 2019, with analysis and recommendations.

Results

Five studies were included in this narrative review. Studies covered a range of mental health symptoms and disorders, including distress, anxiety, depression, sleep disturbance, suicide, adverse alcohol use, illicit drug use, eating disorders and bipolar disorder. Results indicated that cricketers are at high risk for distress, anxiety, depression and adverse alcohol use. When compared with the general population, cricketers are more likely to experience anxiety and depressive symptoms. Rates of suicide were proposed to be high for test cricketers. Overall, studies to date have been of low quality, demonstrating non-rigorous research methods. Some studies have relied on non-validated questionnaires to collect self-reported data on mental health symptoms and disorders, while others have presented biographical data obtained through searches of the media.

Conclusions

The results of this narrative review highlight the lack of evidence underpinning mental health services for athletes within cricket. We suggest the following recommendations for future research and practice: (i) normalising mental health symptoms and disorders; (ii) working with and helping vulnerable demographic segments within the target population; (iii) designing and implementing early recognition systems of mental health symptoms and disorders; (iv) addressing the mental health needs of cricketers on a population basis.

Biomechanical risk factors of lower back pain in cricket fast bowlers using inertial measurement units: a prospective and retrospective investigation

Objectives

To investigate spinal kinematics, tibial and sacral impacts during fast bowling, among bowlers with a history of low back pain (LBP) (retrospective) and bowlers who developed LBP in the follow-up season (prospective).

Methods

35 elite male fast bowlers; senior (n=14; age=24.1±4.3 years; height=1.89±0.05 m; weight=89.2±4.6 kg) and junior (n=21; age=16.9±0.7; height=1.81±0.05; weight=73.0±9.2 kg) were recruited from professional county cricket clubs. LBP history was gathered by questionnaire and development of LBP was monitored for the follow-up season. Spinal kinematics, tibial and sacral impacts were captured using inertial measurement units placed over S1, L1, T1 and anteromedial tibia. Bonferroni corrected pairwise comparisons and effect sizes were calculated to investigate differences in retrospective and prospective LBP groups.

Results

Approximately 38% of juniors (n=8) and 57% of seniors (n=8) reported a history of LBP. No differences were evident in spinal kinematics or impacts between those with LBP history and those without for seniors and juniors. Large effect sizes suggest greater rotation during wind-up (d=1.3) and faster time-to-peak tibial impacts (d=1.5) in those with no history of LBP. One junior (5%) and four (29%) seniors developed LBP. No differences were evident in spinal kinematics or impacts between those who developed LBP and those who did not for seniors. In seniors, those who developed LBP had lower tibial impacts (d=1.3) and greater lumbar extension (d=1.9) during delivery.

Conclusion

Retrospective analysis displayed non-significant differences in kinematics and impacts. It is unclear if these are adaptive or impairments. Prospective analysis demonstrated large effect sizes for lumbar extension during bowling suggesting a target for future coaching interventions.

Stress Injuries of the Spine in Sports

Spine sports stress injuries account for a significant amount of time loss at play in athletes, particularly if left unrecognized and allowed to progress. Spondylolysis makes up most of these stress injuries. This article focuses on spondylolysis, bringing together discussion from the literature on its pathomechanics and the different imaging modalities used in its diagnosis. Radiologists should be aware of the limitations and more importantly the roles of different imaging modalities in guiding and dictating the management of spondylolysis. Other stress-related injuries in the spine are also discussed including but not limited to pedicle fracture and apophyseal ring injury.

Lumbar bone mineral asymmetry in elite cricket fast bowlers

PURPOSE

Bone responds to mechanical loading by increasing bone mineral density (BMD) and/or bone area to enhance bone strength at the site of the greatest strain. Such localised adaptation has not been demonstrated at the spine. The aim of this study is to determine if BMD and/or bone mineral content (BMC) differs between dominant (ipsilateral to bowling/throwing arm) and non-dominant sides of the vertebrae in cricket fast bowlers, and whether this asymmetry differs according to stress fracture or disc injury history. A further aim was to determine if regional BMD and BMC in the lumbar spine differ between fast bowlers, other cricketers, rugby players and non-active controls, to highlight the site-specific response of lumbar vertebra to unilateral activity.

METHODS

23 fast bowlers, 14 other cricketers, 22 rugby players and 20 controls underwent an antero-posterior (AP) and lateral DXA scans of their lumbar spine to assess BMD, BMC and area. A custom analysis measured BMD and BMC of the dominant and non-dominant sides (lateral 33%) of the AP lumbar spine. BMD and BMC were compared between groups, injury status, vertebrae and sides using ANOVA.

RESULTS

Analysis of medical records showed that 6 fast bowlers had a history of lumbar stress fracture. Significantly greater BMD and BMC was found in the L4 non-dominant vertebra compared with the dominant vertebra in fast bowlers. BMD and BMC differed significantly according to vertebra, side and group, with fast bowlers having significantly greater BMD and BMC at the L3 and L4 non-dominant vertebra compared with other groups (L3: 13.3%-45.3%, L4: 15.7%-44.0%) compared with other groups. Fast bowlers who never suffered lumbar stress fracture had 3.6% and 1.7% greater BMD in the dominant and non-dominant sides of lumbar vertebrae respectively compared with those who did suffer lumbar stress fracture, but evidence of this was weaker (P = 0.08).

CONCLUSION

The lumbar spine responds to a unique unilateral high loading activity through site-specific increased bone mass at the site of most strain. Fast bowlers had increased lumbar BMD, particularly on the non-dominant side of L4, although this adaptation was less marked in those with history of lumbar stress fracture. Site-specific low bone mineral density within the lumbar side may be implicated in the aetiology of lumbar stress fracture.