Return to Sports in Stress Reaction and Stress Fractures in Indian Athletes: A Case Series.

Introduction: A stress fracture is a painful condition which occurs when the adaptive ability of the bone is unbalanced. This imbalance predominantly occurs due to increased intensity, frequency, or duration of training. Identifying the etiology of stress fracture and its proper treatment prevents recurrence. Besides, evidence-based and supervised rehabilitation is indispensable for permanent remission of pain and return to sports to preinjury functional levels. The case series discusses the continuum of stress reaction to stress fracture in athletes, causes of stress fractures, their management, and return to sport. The paper aims to give a clear discussion about the management with rehabilitation guidelines for metabolic causes of stress fractures. Case Report: This study was a case series of five cases coming to Sports Medicine outpatient clinic of Sports Injury Centre, VMMC and Safdarjung Hospital, New Delhi, and physical medicine and rehabilitation outpatient clinic of Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow over a period of 1 year. The discussed cases are young Indian athletes, both male and females, who have presentation along the continuum of medial tibial stress syndrome (MTSS) to stress reactions and stress fracture. Conclusion: The findings of the paper highlight the significance of rehabilitation for individuals suffering from MTSS. Accurate diagnosis with targeted rehabilitation leads to quicker return to sports. The rehabilitation program comprises of identifying and treating the cause of stress fracture, removing any risk factors, biomechanical correction wherever indicated, structured exercise program, training in underwater treadmill, cyclical increase in loading, reducing activity every 3rd week.

Case Report: Lumbar spondylolisthesis with unilateral pedicle cleft and contralateral spondylolysis: a report of two cases and literature review.

Background: The causes of pedicle cleft include congenital dysplasia and stress fractures, both of which are rare conditions. Secondary lumbar spondylolisthesis with combined unilateral pedicle cleft and contralateral spondylolysis is extremely rare and can be easily misdiagnosed. We report two cases with these conditions from different causes and discuss the diagnostic and therapeutic features in the context of the literature review. Case description: Case 1 was a 58-year-old female with a stress fracture change at the left L5 pedicle. Case 2 was a 47-year-old female with a pedicle cleft due to hypoplasia of the left L5 pedicle. Both patients had a combined contralateral spondylolysis and Meyerding grade one lumbar spondylolisthesis, while neither had a clear history of lumbar trauma. After initial conservative treatments failed, both patients underwent a single-segment posterior lumbar interbody fusion with bilateral pedicle screw fixation. Both patients were followed up for more than 1 year postoperatively with clinical symptom relief and bony fusion at the pedicle cleft suggested by a CT scan. Conclusion: Lumbar spondylolisthesis with unilateral pedicle cleft and contralateral spondylolysis is rarely reported and can be clinically misdiagnosed as simple spondylolisthesis with bilateral spondylolysis. There is no widely accepted surgical option for patients for whom conservative treatment has failed. Our experience suggests that good clinical results may be achieved by single-segment posterior interbody fusion and bilateral pedicle screw fixation. Precise screw placement into the deficient pedicle and sufficient exiting nerve decompression are prerequisites for the success of this surgical option.

Multiple stress fractures: A case report and discussion.

Stress fracture is the result of bone destruction with prolonged and repetitive loading. It usually occurs among various groups, including athletes, military recruits, and others. Early stress fractures often undergo undiagnosed or misdiagnosed because of atypical symptoms and effective medical examination. Here, we report a rare clinical case about the multiple stress fractures in one adolescent. Expect for the pathological biopsy, it hardly gets confirm diagnosis. With the increasing population of sports lover, healthcare institutions should be enhanced their understanding of stress fractures and enable effective management at an early stage.

Most elite athletes return to preinjury competitive activity after surgical treatment for medial malleolus stress fractures.

PURPOSE: To provide return-to-performance outcomes after surgical treatment for medial malleolus stress fractures in the elite athlete. Additionally, to describe an individualised surgical approach in the management of medial malleolus stress fractures. METHODS: Five athletes (six ankles) underwent surgical treatment for a medial malleolus stress fracture. The surgical technique was based on the extent of the fracture line in steps with first arthroscopic debridement of bony spurs, microfracturing of the fracture line and screw fixation. Return-to-performance data included time to return to sport-specific training, normal training, first competitive activity, performance and the return-to-performance rate. RESULTS: Patients returned to sport-specific training at a median of 10 weeks. They started normal training at 16 weeks postoperatively and returned to their first competitive activity after 19 weeks. All patients had bony spurs on the distal tibia which were arthroscopically debrided. One patient received arthroscopic debridement of bony spurs alone. Four patients received additional microfracturing of the fracture line and three patients received screw fixation. All patients achieved clinical and radiographic union on follow-up computed tomography scan at 3 months postsurgery. At latest follow-up, no refractures nor hardware complications, nor any other complications were observed. CONCLUSION: Arthroscopic debridement of bony spurs, debridement and microfracturing of the fracture line and screw fixation are all viable surgical tools in the management of medial malleolus stress fractures in elite athletes. The surgical approach containing these options should be tailored to the individual athlete based on the fracture line in the sagittal plane. While most athletes return to full competitive activity in 3-4 months, time to self-reported return to full performance is often much longer. LEVEL OF EVIDENCE: Level IV.

Long term follow up on treatment of hallux sesamoid fracture with temporary first metatarsal joint internal fixation.

Fracture of the hallucial sesamoids is a pathology that causes difficulty for surgeons and patients. Because of the low incidence and the fact that up to 64-90 % heal with non-operative management, there is a lack of clear guidance in the literature for the surgical treatment of sesamoid fracture in cases of failure of non-operative management. Here long term follow up of an alternative method of surgical treatment of sesamoid fracture recalcitrant to nonoperative management is presented. 32 individuals were treated with temporary surgical immobilisation of the 1st metatarsophalangeal joint using either crossed wires or two orthogonally placed two hole plates. The patients then underwent removal of the construct at 8 weeks post op after confirmation of healing on a CT scan. There was a 94 % union rate. Return to work was 61 days (15-90) return to sport 80 days (64-112) with no immediate complications and no recurrence. At last follow up mean 10 years (4-16) only 2 patients had gone on to asymptomatic non-union and one patient developed arthritis between the sesamoid and the metatarsal head. No patient has required further surgical intervention. This retrospective cohort of patients demonstrate that this method of treatment is a valuable option in the management of sesamoid fracture which does not alter the biomechanics of the foot and has none of the long term complications of sesamoidectomy or partial sesamoidectomy.

Iron status is associated with tibial structure and vitamin D metabolites in healthy young men.

The influence of iron on collagen synthesis and vitamin D metabolism has implications for bone health. This cross-sectional observational study investigated associations between markers of iron status and tibial structure, vitamin D metabolites, and circulating biochemical markers of bone metabolism in young healthy men. A total of 343 male British Army recruits participated (age 22 ± 3 y, height 1.77 ± 0.06 m, body mass 75.5 ± 10.1 kg). Circulating biochemical markers of iron status, vitamin D metabolites, and bone metabolism, and tibial structure and density by high-resolution peripheral quantitative computed tomography scans (HRpQCT) were measured in participants during week 1 of basic military training. Associations between markers of iron status and HRpQCT outcomes, bone metabolism, and vitamin D metabolites were tested, controlling for age, height, lean body mass, and childhood exercise volume. Higher ferritin was associated with higher total, trabecular, and cortical volumetric bone mineral density, trabecular volume, cortical area and thickness, stiffness, and failure load (all p ≤ 0.037). Higher soluble transferrin receptor (sTfR) was associated with lower trabecular number, and higher trabecular thickness and separation, cortical thickness, and cortical pore diameter (all p ≤ 0.033). Higher haemoglobin was associated with higher cortical thickness (p = 0.043). Higher ferritin was associated with lower ßCTX, PINP, total 25(OH)D, and total 24,25(OH)2D, and higher 1,25(OH)2D:24,25(OH)2D ratio (all p ≤ 0.029). Higher sTfR was associated with higher PINP, total 25(OH)D, and total 24,25(OH)2D (all p ≤ 0.025). The greater density, size, and strength of the tibia, and lower circulating concentrations of markers of bone resorption and formation with better iron stores (higher ferritin) are likely as a result of the direct role of iron in collagen synthesis.

Postoperative Medial Malleolar Fractures in Total Ankle Replacement Are Associated With Decreased Medial Malleolar Width and Varus Malalignment: A Case-Control Study.

BACKGROUND: There are limited data regarding risk factors associated with periprosthetic medial malleolar fractures in total ankle arthroplasty (TAA). This case-control study aimed to identify the risk factors and analyze the effect of prophylactic screw fixation in preventing a medial malleolar fracture after TAA. METHODS: A case-control study was conducted on 149 patients who underwent primary TAA. Twenty patients with postoperative medial malleolar fractures >4 weeks postoperatively (cases) were identified. An additional 129 patients (controls) were randomly selected from the TAA database. Radiographic evaluation included tibial component coronal alignment and postoperative medial malleolar width. Demographics and radiographic variables were compared between cohorts. Logistic regression was used to investigate the association between medial malleolar fracture and postoperative coronal alignment, medial malleolar width, and prophylactic fixation of the medial malleolus. RESULTS: Mean (SD) medial malleolar width was significantly smaller in the fracture cohort (8.52 mm [1.6]) than in the control group (11.78 mm [1.74]) (P < .001). Mean (SD) tibial component coronal alignment was 92.17 degrees (2.77) in the fracture cohort and 90.21 degrees (1.66) in the control group (P = .002). Regression analysis identified a significant negative association between postoperative medial malleolar width and the probability of fracture (OR = 0.06, 95% CI 0.01, 0.26, P < .001). Varus malalignment of the tibial component was positively associated with the probability of fracture (OR = 1.90, 95% CI 1.27, 2.86, P = .002). Prophylactic screw fixation resulted in more than 90% reduction in the odds of a fracture (OR = 0.04, 95% CI 0.01, 0.45, P = .01). ROC curve analysis determined a medial malleolar width of 10.3 mm as a potential threshold for predicting fracture. CONCLUSION: Decreased medial malleolar width and postoperative varus malalignment were associated with an increased risk of postoperative medial malleolar fracture. Therefore, surgeons should consider prophylactic screw fixation in patients with a medial malleolar width <10.3 mm or at risk of postoperative varus deformity.

Hydrodissection of the Eighth Cervical Nerve Root for Scapular Girdle Pain Associated With Nonunion of the First Rib Stress Fracture: A Case Report.

The first rib stress fracture is a rare overuse injury, with nonunion posing challenges to athletic performance. We report an 18-year-old international-level gymnast diagnosed with the nonunion of the first rib stress fracture, experiencing pain extending to the medial scapular area. Traditional treatments provided no relief, with tests suggesting C8 nerve root involvement. This study introduces a novel approach targeting the C8 nerve root using hydrodissection, which alleviates the pain. Post-procedure, the patient resumed competition without recurrence of pain after a year. This case suggests that pain due to first rib stress fracture nonunion might be associated with the C8 nerve root, and hydrodissection could be a potentially effective treatment.

Factors Associated With High-Risk and Low-Risk Bone Stress Injury in Female Runners: Implications for Risk Factor Stratification and Management.

Background: Bone stress injury (BSI) is a common overuse injury in active women. BSIs can be classified as high-risk (pelvis, sacrum, and femoral neck) or low-risk (tibia, fibula, and metatarsals). Risk factors for BSI include low energy availability, menstrual dysfunction, and poor bone health. Higher vertical load rates during running have been observed in women with a history of BSI. Purpose/Hypothesis: The purpose of this study was to characterize factors associated with BSI in a population of premenopausal women, comparing those with a history of high-risk or low-risk BSI with those with no history of BSI. It was hypothesized that women with a history of high-risk BSI would be more likely to exhibit lower bone mineral density (BMD) and related factors and less favorable bone microarchitecture compared with women with a history of low-risk BSI. In contrast, women with a history of low-risk BSI would have higher load rates. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Enrolled were 15 women with a history of high-risk BSI, 15 with a history of low-risk BSI, and 15 with no history of BSI. BMD for the whole body, hip, and spine was standardized using z scores on dual-energy x-ray absorptiometry. High-resolution peripheral quantitative computed tomography was used to quantify bone microarchitecture at the radius and distal tibia. Participants completed surveys characterizing factors that influence bone health-including sleep, menstrual history, and eating behaviors-utilizing the Eating Disorder Examination Questionnaire (EDE-Q). Each participant completed a biomechanical assessment using an instrumented treadmill to measure load rates before and after a run to exertion. Results: Women with a history of high-risk BSI had lower spine z scores than those with low-risk BSI (-1.04 ± 0.76 vs -0.01 ± 1.15; P < .05). Women with a history of high-risk BSI, compared with low-risk BSI and no BSI, had the highest EDE-Q subscores for Shape Concern (1.46 ± 1.28 vs 0.76 ± 0.78 and 0.43 ± 0.43) and Eating Concern (0.55 ± 0.75 vs 0.16 ± 0.38 and 0.11 ± 0.21), as well as the greatest difference between minimum and maximum weight at current height (11.3 ± 5.4 vs 7.7 ± 2.9 and 7.6 ± 3.3 kg) (P < .05 for all). Women with a history of high-risk BSI were more likely than those with no history of BSI to sleep <7 hours on average per night during the week (80% vs 33.3%; P < .05). The mean and instantaneous vertical load rates were not different between groups. Conclusion: Women with a history of high-risk BSI were more likely to exhibit risk factors for poor bone health, including lower BMD, while load rates did not distinguish women with a history of BSI.

Biomechanical role of bone grafting for calcaneal fracture fixation in the presence of bone defect: A finite element analysis.

BACKGROUND: The purpose of this study was to compare the biomechanical stress and stability of calcaneal fixations with and without bone defect, before and after bone grafting, through a computational approach. METHODS: A finite element model of foot-ankle complex was reconstructed, impoverished with a Sanders III calcaneal fracture without bone defect and with moderate and severe bone defects. Plate fixations with and without bone grafting were introduced with walking stance simulated. The stress and fragment displacement of the calcaneus were evaluated. FINDINGS: Moderate and severe defect increased the calcaneus stress by 16.11% and 32.51%, respectively and subsequently decreased by 10.76% and 20.78% after bone grafting. The total displacement was increased by 3.99% and 24.26%, respectively by moderate and severe defect, while that of posterior joint facet displacement was 86.66% and 104.44%. The former was decreased by 25.73% and 35.96% after grafting, while that of the latter was reduced by 88.09% and 84.78% for moderate and severe defect, respectively. INTERPRETATION: Our finite element prediction supported that bone grafting for fixation could enhance the stability and reduce the risk of secondary stress fracture in cases of bone defect in calcaneal fracture.

Consecutive Bilateral Iliac Stress Fracture in an Adult Male Runner.

Iliac stress fractures (ISF) are uncommon in sports, particularly among runners, and are attributed to repetitive loading and other predisposing factors. ISF poses diagnostic challenges due to nonspecific symptoms and the limited sensitivity of conventional imaging procedures. The reported case is about a 51-year-old male marathon runner with consecutive bilateral ISF. Initial symptoms included mechanical pain in the right buttock, leading to a diagnosis confirmed via pelvic MRI. Conservative management with eight weeks rest from sport activity was indicated with symptom resolution and return to sport. However, 20 days after returning to sport, the patient developed left-sided symptoms post-resumption of running, with MRI confirming a new ISF. An additional eight weeks of rest was prescribed, allowing the patient to resume sport at preinjury levels. ISF should be considered in runners presenting with gluteal pain, emphasizing the importance of early diagnosis. MRI emerges as a valuable tool for accurate diagnosis, guiding appropriate management strategies. Conservative management focusing on rest is paramount for favorable outcomes and optimizing runners' health and performance.

Effect of age on ankle biomechanics and tibial compression during stair descent.

BACKGROUND: Stress fracture is a concern among older adults, as age-related decrements in ankle neuromuscular function may impair their ability to attenuate tibial compressive forces experienced during daily locomotor tasks, such as stair descent. Yet, it is unknown if older adults exhibit greater tibial compression than their younger counterparts when descending stairs. RESEARCH QUESTION: Do older adults exhibit differences in ankle biomechanics that alter their tibial compression during stair descent compared to young adults, and is there a relation between tibial compression and specific changes in ankle biomechanics? METHODS: Thirteen young (18-25 years) and 13 older (> 65 years) adults had ankle joint biomechanics and tibial compression quantified during a stair descent. Discrete ankle biomechanics (peak joint angle and moment, and joint stiffness) and tibial compression (maximum and impulse) measures were submitted to an independent t-test, while ankle joint angle and moment, and tibial compression waveforms were submitted to an independent statistical parametric mapping t-test to determine group differences. Pearson correlation coefficients (r) determined the relation between discrete ankle biomechanics and tibial compression measures for all participants, and each group. RESULTS: Older adults exhibited smaller maximum tibial compression (p = 0.004) from decreases in peak ankle joint angle and moment between 17 % and 34 % (p = 0.035), and 20-31 % of stance (p < 0.001) than young adults. Ankle biomechanics exhibited a negligible to weak correlation with tibial compression for all participants, with peak ankle joint moment and maximum tibial compression (r = -0.48 ±â€¯0.32) relation the strongest. Older adults typically exhibited a stronger relation between ankle biomechanics and tibial compression (e.g., r = -0.48 ±â€¯0.47 vs r = -0.27 ±â€¯0.52 between peak ankle joint moment and maximum tibial compression). SIGNIFICANCE: Older adults altered ankle biomechanics and decreased maximum tibial compression to safely execute the stair descent. Yet, specific alterations in ankle biomechanics could not be identified as a predictor of changes in tibial compression.

Tibial strains are sensitive to speed perturbations, but not grade perturbations, during running.

A fatigue-failure process is hypothesized to govern the development of tibial stress fractures, where bone damage is highly dependent on the peak strain magnitude. To date, much of the work examining tibial strain during running has ignored uphill and downhill running despite the prevalence of this terrain. This study examined the sensitivity of tibial strain to changes in running grade and speed using a combined musculoskeletal-finite element modelling routine. Seventeen participants ran on a treadmill at ±10, ±5 and 0 deg; at each grade, participants ran at 3.33 m s-1 and at a grade-adjusted speed of 2.50 and 4.17 m s-1 for uphill and downhill grades, respectively. Force and motion data were recorded in each grade and speed combination. Muscle and joint contact forces were estimated using inverse-dynamics-based static optimization. These forces were applied to a participant-adjusted finite element model of the tibia. None of the strain variables (50th and 95th percentile strain and strained volume ≥4000 µÎµ) differed as a function of running grade; however, all strain variables were sensitive to running speed (F1≥9.59, P≤0.03). In particular, a 1 m s-1 increase in speed resulted in a 9% (∼260 µÎµ) and 155% (∼600 mm3) increase in peak strain and strained volume, respectively. Overall, these findings suggest that faster running speeds, but not changes in running grade, may be more deleterious to the tibia.

Stress fracture of the clavicle associated with sternocostoclavicular hyperostosis combined with bony ankylosis of the acromioclavicular joint and ossification of the coracoclavicular ligament.

Sternocostoclavicular hyperostosis (SCCH) has been reported in patients with pustulotic arthro-osteitis, but there are few reports of marked ossification of the lateral part of the clavicle. Here, we report a case of stress fracture in a patient with SCCH with marked ossification of the lateral part of the clavicle. In this case, the clavicular fracture was proximal and no dislocation. Conservative treatment with a clavicle band and the administration of corticosteroids resulted in rapid symptom improvement. Eight months later, the patient had no difficulty in daily life, but X-rays showed that bone fusion was not complete. Therefore, it is necessary to carefully follow-up such patients for any recurrence of symptoms and radiographic changes.

Anatomy of the Naviculocuneiform Joint Complex.

Background: The purpose of this study was to quantify the articular surfaces of the naviculocuneiform (NC) joint to help clinicians better understand common pathologies observed such as navicular stress fractures and arthrodesis nonunions. Methods: Twenty cadaver NC joints were dissected and the articular cartilage of the navicular, medial, middle, and lateral cuneiforms were quantified by calibrated digital imaging software. Statistical analysis included calculating the mean cartilage surface area dimensions of the distal navicular and proximal cuneiform bones. Length measurements on the navicular were obtained to estimate the geographic location of the interfacet ridges. Lastly, all facets of the articular surfaces were described in regard to the shape and location of cartilaginous or fibrous components. Results were compared using Student t tests. Results: Navicular cartilage was present over 75.4% of the surface area of the proximal NC joint, compared with 72.6% of combined cuneiform cartilage distally. The mean height of the deepest (dorsal-plantar) measurement of navicular articular cartilage was 18 ± 3 mm. The mean heights of the distal medial, middle, and lateral cuneiform articular facets were 15 ± 1 mm, 17 ± 2 mm, and 15 ± 2 mm, respectively. Conclusion: There is significant variation among the articular surfaces of the NC joint. Additionally, the central third of the navicular was calculated to lie in the inter-facet ridge between the medial and middle articular facets of the navicular. Clinical Relevance: Surgeons may consider this study data when performing joint preparation for NC arthrodesis as cartilage was present to a mean depth of 18 mm at the NC joint. Additionally, this study demonstrates that the central third of the navicular, where most navicular stress fractures occur, lies in the interfacet ridge between the medial and middle articular facets of the navicular.

Effective Management of Sacral Stress Fractures in Gastric Cancer: Iliosacral Screw Fixation Following a Type 3 Hemipelvectomy.

Metastatic pelvic tumors pose a significant challenge in oncologic orthopedics due to their complex management and the high potential for postoperative complications. This case study discusses a 75-year-old male with a sacral stress fracture following a type 3 internal hemipelvectomy for a metastatic lesion from gastric cancer in the left pubic bone. Initial conservative treatments failed to yield satisfactory improvement, leading to surgical intervention. Open reduction and internal fixation with an iliosacral screw, despite complications, significantly alleviated pain and improved mobility. This case underscores the difficulty in diagnosing sacral stress fractures versus metastatic lesions and highlights the effectiveness of iliosacral screw fixation in managing postoperative sacral stress fractures. It emphasizes the procedure's role in providing early pain relief and enhancing daily activity levels. Additionally, it points out the importance of addressing altered bone metabolism in the postoperative care of patients with metastatic pelvic tumors. This contributes to the literature by stressing the incidence of sacral stress fractures as a critical, though often overlooked, complication and demonstrating the benefits of iliosacral screw fixation in such scenarios for better recovery and quality of life.

Epidemiology of Stress Fracture in Police Trainees.

BACKGROUND: Military recruits and athletes have high occurrence of stress fractures, with very high incidence among military recruits. Symptomatic stress fractures can be disabling in some people. This study aims at identifying pattern and distribution of such fractures in Nepal Police trainee and assess the risk factors and demographics that may help to develop the local guidelines. METHODS: This study analysed 65 police trainees who presented to the orthopaedic Out Patient Department at Nepal Police and Province Police Hospital diagnosed as a case of stress fracture from 29 December, 2020 to 29 December, 2021. Ethical approval was obtained and different variables analysed were age, sex, Body Mass Index, location of fracture, duration of pain, method of treatment, time to heal the fracture and time to pain free mobilisation of patient. RESULTS: There were 65 trainees with 86 sites of fracture at different bones with 50.8% (33) of male population. The majority of fracture was located at tibia (58.1%) followed by pubic rami (33.7%) with potentially debilitating fracture neck of femur seen in 4.6% subjects. Mean duration of pain was 20.7±14.2 days with mean time for pain free mobilisation 42.2±17.7 days after presentation. 96.5% of those recovered with conservative treatment (activity restriction or cast). CONCLUSIONS: The location of stress fracture depends upon the type of training or activities. Modification of activities in early phase of training with early visit for medical care in case of trainees with increasing pain may decrease morbidities and complications requiring operative treatment.

Subchondral bone fatigue injury in the parasagittal condylar grooves of the third metacarpal bone in thoroughbred racehorses elevates site-specific strain concentration.

Condylar stress fracture of the distal end of the third metacarpal/metatarsal (MC3/MT3) bones is a major cause of Thoroughbred racehorse injury and euthanasia worldwide. Functional adaptation to exercise and fatigue damage lead to structural changes in the subchondral bone that include increased modeling (resulting in sclerotic bone tissue) and targeted remodeling repair (resulting in focal resorption spaces in the parasagittal groove). Whether these focal structural changes, as detectable by standing computed tomography (sCT), lead to elevated strain at the common site of condylar stress fracture has not been demonstrated. Therefore, the goal of the present study was to compare full-field three-dimensional (3D) strain on the distopalmar aspect of MC3 bone specimens with and without focal subchondral bone injury (SBI). Thirteen forelimb specimens were collected from racing Thoroughbreds for mechanical testing ex vivo and underwent sCT. Subsequently, full-field displacement and strain at the joint surface were determined using stereo digital image correlation. Strain concentration was observed in the parasagittal groove (PSG) of the loaded condyles, and those with SBI in the PSG showed higher strain rates in this region than control bones. PSG strain rate in condyles with PSG SBI was more sensitive to CT density distribution in comparison with condyles with no sCT-detectable injury. Findings from this study help to interpret structural changes in the subchondral bone due to fatigue damage and to assess risk of incipient stress fracture in a patient-specific manner.