Search

Background: Magnetic resonance imaging (MRI) scans and radiographs are often utilized in assessing for preoperative osteoarthritis in patients undergoing hip preservation surgery. Purpose: To determine if MRI scans improve inter- or intrarater reliabilities over radiographs for findings of hip arthritis. Study Design: Cohort study (Diagnosis); Level of evidence, 3. Methods: Anteroposterior and cross-table lateral radiographs as well as a representative coronal and sagittal T2-weighted MRI scan were reviewed for 50 patients by 7 experienced subspecialty hip preservation surgeons, with a minimum experience of 10 years. Radiographs and MRI scans were assessed for joint space narrowing, subchondral cysts, osteophytes, subchondral sclerosis, Likert osteoarthritis grade (none, mild, moderate, or severe), and Tönnis grade. MRI scans were also evaluated for bony edema, heterogeneous articular cartilage, and chondral defects. Inter- and intrarater reliabilities were calculated utilizing the Fleiss method with a 95% CI. Results: The scans of 50 patients (28 female and 22 male) with a mean age of 42.8 years (SD, 14.2 years; range, 19-70 years) were reviewed. Radiographs revealed fair agreement for joint space narrowing (κ = 0.25 [95% CI, 0.21-0.30]), osteophytes (κ = 0.26 [95% CI, 0.14-0.40]), Likert osteoarthritis grading (κ = 0.33 [95% CI, 0.28-0.37]) and Tönnis grade (κ = 0.30 [95% CI, 0.26-0.34). Radiographs revealed moderate agreement for subchondral cysts (κ = 0.53 [95% CI, 0.35-0.69]). MRI scans demonstrated poor to fair agreement for joint space narrowing (κ = 0.15 [95% CI, 0.09-0.21]), subchondral sclerosis (κ = 0.27 [0.19-0.34]), heterogeneous articular cartilage (κ = 0.07 [95% CI, 0.00-0.14]), Likert osteoarthritis grade (κ = 0.19 [95% CI, 0.15-0.24]), and Tönnis grade (κ = 0.20 [95% CI, 0.15-0.24]). MRI scans demonstrated substantial agreement for subchondral cysts (κ = 0.73 [95% CI, 0.63-0.83]). Intrarater reliabilities were statistically improved compared with interrater reliabilities, but no differences were found between radiographs and MRI scans for joint space narrowing, subchondral cysts, osteophytes, osteoarthritis grade, or Tönnis grade. Conclusion: Radiographs and MRI scans had substantial limitations and inconsistency between raters in evaluating common markers of hip osteoarthritis. MRI scans demonstrated strong reliability in evaluating for subchondral cysts but did not improve the interobserver variability of grading hip arthritis.

Background: Several techniques for hip capsular reconstruction have been described to address gross instability or microinstability due to capsular deficiency. However, objective biomechanical data to support their use are lacking. Purpose: To compare the kinematic effect of 2 capsular reconstruction techniques (iliotibial band [ITB] graft and Achilles tendon graft). Kinematic effect encompassed rotational range of motion (ROM) as well as joint translation in the coronal, sagittal, and axial planes. Study Design: Controlled laboratory study. Methods: 8 paired, fresh-frozen hemi-pelvises (16 hips) were tested on a custom-designed joint motion simulator in the intact state and after capsulectomy. Pairs were randomly allocated to either ITB or Achilles reconstruction and retested. Testing was performed at 0°, 45°, and 90° of flexion. Internal-external rotation (IR-ER) torques and abduction-adduction torques of 3 N·m were applied to the femur via a load cell at each position, and rotational ROM and joint translation in the coronal, sagittal, and axial planes were recorded. Results: At 45° and 90°, there was a significant effect of the condition of the hip on the total IR-ER ( P = .004, effect size [ES] = 0.305; and P < .001, ES = 0.497; respectively). At 45°, mean ± SD total rotation was significantly greater for the capsulectomy (59.7°± 15.9°) state compared with intact (53.3°± 13.2°; P = .007). At 90°, reconstruction significantly decreased total rotation to 49.0°± 18.9° compared with a mean total rotation of 52.8°± 18.7° after capsulectomy ( P = .02). No difference was seen in the total abduction-adduction of the hip between conditions. Comparisons of the 2 different reconstruction techniques showed no significant differences in total IR-ER or abduction-adduction ROM or joint translation in the coronal, sagittal, or axial planes. For translation, at both 0° and 45° there was a statistically significant effect of the condition on the medial-lateral translation ( P = .033; ES = 0.204). Reconstruction, independent of technique, was successful in significantly decreasing ( P = .030; P = .014) the mean medial-lateral translation at 0° and 45° of hip flexion from 5.2 ± 3.8 mm and 5.6 ± 4.0 mm to 2.8 ± 1.9 mm and 3.9 ± 3.2 mm, respectively. Conclusion: The integrity of the native hip capsule played a significant role in rotational stability, where capsulectomy significantly increased rotational ROM. Both ITB and Achilles reconstruction techniques restored normal rotational ROM of the hip at 90° of flexion as well as coronal plane stability at 0° and 45° of hip flexion. No differences were seen between ITB and Achilles reconstruction techniques. Clinical Relevance: Both capsular reconstruction techniques provide comparable joint kinematics, restoring rotation and translation to normal values with the exception of rotational ROM at 45°, which remained significantly greater than the intact state. The most significant results were the rotational stability at 90° of hip flexion and coronal plane stability at 0° and 45° of hip flexion, which were significantly improved compared with the capsulectomy state.

Background: Femoroacetabular impingement syndrome (FAIS) is a common cause of hip pain and disability in athletes. Arthroscopic treatment for FAIS is well-established; however, the long-term results in elite athletes are limited. Purpose: To evaluate outcomes 5 years after arthroscopic treatment for FAIS in elite athletes. Study Design: Case series; Level of evidence, 4. Methods: Elite athletes undergoing arthroscopic treatment for FAIS with a minimum 5-year follow-up were included. They were prospectively followed up with patient-reported outcome measures. An elite athlete was defined as having a Hip Sports Activity Scale (HSAS) level of 7 or 8 before the onset of symptoms. Preoperatively and 5 years after surgery, all athletes completed a web-based questionnaire, including the Copenhagen Hip and Groin Outcome Score (comprising 6 subscales), the EQ-5D and EQ-VAS (European Quality of Life–5 Dimensions Questionnaire and European Quality of Life–Visual Analog Scale), iHOT-12 (International Hip Outcome Tool), a visual analog scale for hip function, and the HSAS. Moreover, patients reported their overall satisfaction with their hip function. Preoperative measurements were compared with the 5-year follow-up. Results: A total of 64 elite athletes (52 men, 12 women) with a mean ± SD age of 24 ± 6 years were included. On average, patients reported a statistically significant and clinically relevant improvement from preoperative patient-reported outcome measures to the 5-year follow-up ( P < .0003), Copenhagen Hip and Groin Outcome Score subscales (symptoms, 51.7 vs 71.9; pain, 61.0 vs 81.1; function of daily living, 67.1 vs 83.6; function in sports and recreation, 40.0 vs 71.5; participation in physical activity, 25.0 vs 67.4; hip and groin–related quality of life, 34.4 vs 68.0), EQ-5D (0.60 vs 0.83), EQ-VAS (66.1 vs 76.7), and iHOT-12 (40.0 vs 68.8). At the 5-year follow-up, 90.5% reported satisfaction with their overall hip function. In total, 54% still participated in competitive sports (HSAS, 5-8) at follow-up, while 77% had decreased their level. Older patients and patients with longer duration of symptoms reported a significantly lower level of sports activity (HSAS, 0-4; P < .009). Conclusion: Arthroscopic treatment for FAIS in elite athletes results in a statistically significant and clinically relevant improvement regarding symptoms, hip function, quality of life, and pain 5 years after surgery. Approximately half of the cohort was still in competitive sports at follow-up, yet 77% had decreased their level of sports. Nine of 10 patients were satisfied with their surgery.

Background: The decreased hip range of motion seen in femoroacetabular impingement syndrome (FAIS) may lead to compensatory increased motion at the symphysis pubis (SP) with resultant increased stress on the joint, which can subsequently lead to osteitis pubis. Purpose: To quantify the prevalence of SP abnormalities in patients with FAIS through the use of imaging modalities and to compare outcomes based on the presence of SP abnormalities. Study Design: Cohort study; Level of evidence, 3. Methods: Radiographs and magnetic resonance imaging (MRI) scans of 1009 consecutive patients who underwent primary hip arthroscopy for FAIS from January 2012 to January 2016 were identified. Exclusion criteria were patients undergoing revision or bilateral surgery, patients with dysplasia, and patients with less than 2-year follow-up. On radiographs, SP joints were reviewed for joint surface erosions, subchondral sclerosis and cysts, and ankylosis. MRI scans were reviewed for marrow edema in the subarticular pubic bone, subchondral sclerosis and cysts, joint surface erosions, and ankylosis. Patients with SP abnormalities were matched 1:2 to patients without SP abnormalities by age and body mass index. Outcomes included the Hip Outcome Score–Activities of Daily Living (HOS-ADL), HOS–Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), International Hip Outcome Tool–12 (iHOT-12), and visual analog scales (VAS) for pain and satisfaction. Results: 830 patients were included; 23 (2.8%) demonstrated SP abnormalities. Of the 726 (72%) MRI scans reviewed, 15 (1.8%) showed bone marrow edema, subchondral sclerosis, erosions, or ankylosis. After matching, patients without SP abnormalities had significantly greater HOS-ADL (95.7 vs 83.0; P = .008), HOS-SS (91.6 vs 61.9; P = .003), iHOT-12 (89.5 vs 74.6; P = .046), and VAS satisfaction (91.3 vs 58.8; P = .004) scores, in addition to less postoperative pain (6.3 vs 23.5; P < .001). No significant differences were found in the mHHS (92.5 vs 82.2; P = .08). Patients without SP abnormalities had higher odds of achieving the minimal clinically important difference for the HOS-ADL (odds ratio [OR], 4.5; 95% CI, 1.3-14.1; P = .010), the HOS-SS (OR, 7.2; 95% CI, 1.8-18.5; P = .006), and the mHHS (OR, 14.5; 95% CI, 1.8-24.7; P = .013). Conclusion: A low prevalence (1.8%-2.6%) of SP joint abnormality is seen on imaging in patients with FAIS. These patients may demonstrate significantly inferior clinical outcomes and persistent postoperative pain after FAIS treatment.

Background: Posterior shoulder instability accounts for a small proportion of all shoulder instability, although it can affect athletes of all types, from contact to overhead athletes. Surgical treatment is quite successful in these patients; however, the literature reports a wide range of rates of return to sport. Purpose/Hypothesis: The purpose was to determine the return-to-sport rates after surgical stabilization for posterior shoulder instability. It was hypothesized that patients would experience a high rate of return to sport. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: Embase, PubMed, and MEDLINE were searched for relevant literature from database inception until April 2020, and studies were screened by 2 reviewers independently and in duplicate for studies reporting rates of return to sport after surgical management of posterior shoulder instability. Demographic data as well as data on return to sport and functional outcomes were recorded. A meta-analysis of proportions was used to combine the rates of return to sport using a random effects model. A risk of bias was assessed for all included studies. Results: Overall, 32 studies met inclusion criteria and comprised 1100 patients (1153 shoulders) with a mean age of 22.8 years (range, 11-65) and a mean follow-up of 43.2 months (range, 10-228). The pooled rate of return to any level of sport was 88% (95% CI, 84%-92%; I2 = 68.7%). In addition, the pooled rate of return to the preinjury level was 68% (95% CI, 60%-76%; I2 = 79%). Moreover, the pooled return-to-sport rate for contact athletes was 94% (95% CI, 90%-97%; I2 = 0%), while for throwing athletes it was 88% (95% CI, 83%-92%; I2 = 0%). Conclusion: Surgical management of posterior shoulder instability resulted in a high rate of return to sport, as well as significant pain reduction and functional improvement in most patients. However, only two-thirds of athletes can return to their preinjury levels of sport.

Background:Femoroacetabular impingement (FAI) is a condition known to cause hip pain in young adults.Purpose:To evaluate the efficacy of the surgical correction of FAI via arthroscopic osteochondroplasty with or without labral repair compared with arthroscopic lavage of the hip joint with or without labral repair.Study Design:Randomized controlled trial; Level of evidence, 1.Methods:A total of 220 male and female participants aged 18 to 50 years with nonarthritic FAI suitable for surgical treatment were recruited for the trial at 10 clinical centers in Canada, Finland, and Denmark between October 2012 and November 2017, of whom 214 were included in the final analysis. In the osteochondroplasty group, cam- and/or pincer-type lesions were resected using fluoroscopic guidance. In the lavage group, the joint was washed out with 3 L of normal saline. Surgeons were instructed to repair the labrum in both groups if it was mechanically unstable once probed, showing visible displacement or chondrolabral separation. The primary outcome was patient-reported pain (using the 100-point visual analog scale [VAS]) at 12 months. Secondary outcomes included hip function (Hip Outcome Score [HOS] and International Hip Outcome Tool), physical and mental health (12-Item Short Form Health Survey), and health utility (EuroQol–5 Dimensions) at 12 months as well as any reoperations and other hip-related adverse events at 24 months.Results:At 12 months, there was no difference in pain (VAS) between the groups (mean difference [MD], 0.11 [95% CI, –7.22 to 7.45]; P = .98). Also, 88.3% (189/214) of participants had a labral tear, of which 60.3% were repaired. For the secondary outcomes, there were no significant differences between treatment groups, with the exception of the HOS activities of daily living domain in which lavage showed significant improvement compared with osteochondroplasty (MD, –5.03 [95% CI, −10.40 to −0.03]; P = .049). By 24 months, there were significantly fewer reoperations reported in the osteochondroplasty group (8/105) than the lavage group (19/104) (odds ratio, 0.37 [95% CI, 0.15-0.89]; P = .026). The primary reasons for a reoperation included hip pain (15/27; 55.6%) and a reinjury of the labrum (11/27; 40.7%).Conclusion:Both the osteochondroplasty and the lavage groups with or without labral repair for FAI had significantly improved pain or function significantly at 1 year. By 2 years, the reoperation rate was significantly lower in the osteochondroplasty group.Registration:NCT01623843 ( ClinicalTrials.gov identifier)

Background: Arthroscopic iliopsoas tendon release is a surgical treatment option for painful snapping hips, although it has been associated with controversy surrounding potential complications including decreased hip flexion strength, iatrogenic hip instability, and iliopsoas atrophy. Purpose: To systematically assess the efficacy and safety of arthroscopic iliopsoas tenotomy during hip arthroscopic surgery as an intervention for painful snapping hips. Study Design: Systematic review; Level of evidence, 4. Methods: A total of 3 online databases (Embase, PubMed, and MEDLINE) were searched from database inception until September 2019 for studies investigating iliopsoas tenotomy during hip arthroscopic surgery. Studies were screened by 2 reviewers independently and in duplicate, and studies investigating arthroscopic iliopsoas tendon release were included. Demographic data as well as data on treatment success, functional outcome scores, and radiological outcomes were recorded. A risk of bias assessment was performed for all included studies. Results: Overall, 21 studies were identified with a total of 824 patients (875 hips). These patients were 82.5% female (680/824), with a mean age of 28.1 years (range, 12-62 years) and mean follow-up of 32.1 months (range, 3-73 months). Arthroscopic iliopsoas tenotomy was performed at the level of the labrum in 811 hips (92.7%) or the lesser trochanter in 64 hips (7.3%). The overall reported success rate of the procedure in resolving snapping hips was 93.0% (266/286), and all studies reported an improvement in functional outcome scores. Only 6 studies (93 hips) discussed postoperative hip flexion strength, with complete recovery of strength reported in 4 studies (47 hips) and mild decreases reported in the other 2 studies (46 hips). Iliopsoas atrophy was evaluated radiologically (3 studies; 66 hips) and was found postoperatively in 92.4% (61/66) of hips. No major complications were reported. Conclusion: Arthroscopic release of the iliopsoas tendon was effective in alleviating pain and persistent clicking associated with a snapping hip. Although patients demonstrated some early postoperative weakness and iliopsoas atrophy on radiological imaging, the results from studies to date showed satisfactory clinical function and return to sports/activities. High-quality comparative studies are needed to further assess arthroscopic iliopsoas tendon release to determine the optimal technique and location of tendon release.

Background: Adult hip dysplasia is often diagnosed according to the lateral center-edge angle (LCEA). Patients with frank hip dysplasia (LCEA Purpose: To perform a narrative review to report the differences in hip morphology and clinical outcomes between adult patients with frank hip dysplasia and BHD. Study Design: Narrative review. Methods: A systematic search of the literature was conducted through the Medline, EMBASE, and Cochrane databases with the search phrase borderline hip dysplasia. Results: The search identified 305 articles, of which 48 were considered relevant to this study after screening of titles and abstracts. Four articles discussed new radiographic means of evaluating adult hip dysplasia, 16 articles analyzed morphology of dysplastic hips, and 28 articles described the clinical outcomes of patients with frank hip dysplasia or BHD treated with hip arthroscopy and/or PAO. Because the level of evidence obtained from this search was not adequate for systematic review or meta-analysis, a current concepts review on the diagnosis, hip morphology, and clinical outcomes of patients with frank hip dysplasia or BHD is presented. Conclusion: Adult hip dysplasia is most commonly diagnosed based on the LCEA; however, the LCEA is an unreliable sole marker for dysplasia, and additional radiographic parameters should be utilized. Furthermore, specific pathology identified on imaging and/or during hip arthroscopy can provide clues to a surgeon when the diagnosis is inconclusive according to history and physical examination alone. While the data support that patients with frank dysplasia are best treated with PAO, there is no such preferred treatment for patients with BHD, who have a wide spectrum of instability. Selective use of arthroscopic labral and capsular treatment alone may provide good results in carefully chosen patients with BHD, while some may end up requiring a bony realignment procedure.

Background:Given the high prevalence of patients with hip deformities and no ongoing hip dysfunction, understanding the anatomic factors predicting the symptomatic state is critical. One such variable is how the spinopelvic parameters (SPPs) may interplay with hip anatomic factors.Hypothesis/Purpose:SPPs and femoral- and acetabular-specific parameters may predict which patients will become symptomatic. The purpose was to determine which anatomic characteristics with specific cutoffs were associated with hip symptom development and how these parameters relate to each other.Study Design:Cohort study (Diagnosis); Level of evidence, 2.Methods:548 participants were designated either symptomatic patients (n = 176, scheduled for surgery with hip pain and/or functional limitation) or asymptomatic volunteers (n = 372, no pain) and underwent 3-dimensional magnetic resonance imaging. Multiple femoral (α angle, Ω angle, neck angle, torsion), acetabular (version, coverage), and spinopelvic (pelvic tilt, sacral slope [SS], pelvic incidence) parameters were measured semiautomatically. Normative values, optimal differentiating thresholds, and a logistic regression analysis were computed.Results:Symptomatic patients had larger cam deformities (defined by increased Ω angle and α angle), smaller acetabular coverage, and larger pelvic incidence and SS angles compared with the asymptomatic volunteers. Discriminant receiver operating characteristic analysis confirmed that radial 2-o’clock α angle (threshold 58°-60°, sensitivity 75%-60%, specificity 80%-84%; area under the curve [AUC] = 0.831), Ω angle (threshold 43°, sensitivity 72%, specificity 70%; AUC = 0.830), acetabular inclination (threshold 6°, sensitivity 65%, specificity 70%; AUC = 0.709), and SS (threshold 44°, sensitivity 72%, specificity 75%; AUC = 0.801) ( P < .005) were the best parameters to classify participants. When parameters were entered into a logistic regression, significant positive predictors for the symptomatic patients were achieved for SS, acetabular inclination, Ω angle, and α angle at 2-o’clock, correctly classifying 85% of cases (model sensitivity 72%, specificity 91%; AUC = 0.919).Conclusion:Complex dynamic interplay exists between the hip and SPPs. A cam deformity, acetabular undercoverage, and increased SPP angles are predictive of a hip symptomatic state. SPPs were significant to discriminate between participants and were important in combination with other hip deformities. Symptomatic patients can be effectively differentiated from asymptomatic volunteers based on predictive anatomic factors.

Background: Focal cartilage defects of the knee are a substantial cause of pain and disability in active patients. There has been an emergence of randomized controlled trials evaluating surgical techniques to manage such injuries, including marrow stimulation (MS), autologous chondrocyte implantation (ACI), and osteochondral autograft transfer (OAT). Purpose: A meta-analysis was conducted to determine if any single technique provides superior clinical results at intermediate follow-up. Study Design: Systematic review and meta-analysis of randomized controlled trials. Methods: The MEDLINE, EMBASE, and Cochrane Library databases were systematically searched and supplemented with manual searches of PubMed and reference lists. Eligible studies consisted exclusively of randomized controlled trials comparing MS, ACI, or OAT techniques in patients with focal cartilage defects of the knee. The primary outcome of interest was function (Lysholm score, International Knee Documentation Committee score, Knee Osteoarthritis Outcome Score) and pain at 24 months postoperatively. A meta-analysis using standardized mean differences was performed to provide a pooled estimate of effect comparing treatments. Results: A total of 12 eligible randomized trials with a cumulative sample size of 765 patients (62% males) and a mean (±SD) lesion size of 3.9 ± 1.3 cm2 were included in this review. There were 5 trials comparing ACI with MS, 3 comparing ACI with OAT, and 3 evaluating different generations of ACI. In a pooled analysis comparing ACI with MS, there was no difference in outcomes at 24-month follow-up for function (standardized mean difference, 0.47 [95% CI, –0.19 to 1.13]; P = .16) or pain (standardized mean difference, –0.13 [95% CI, –0.39 to 0.13]; P = .33). The comparisons of ACI to OAT or between different generations of ACI were not amenable to pooled analysis. Overall, 5 of the 6 trials concluded that there was no significant difference in functional outcomes between ACI and OAT or between generations of ACI. Conclusion: There is no significant difference between MS, ACI, and OAT in improving function and pain at intermediate-term follow-up. Further randomized trials with long-term outcomes are warranted.

Background:High-quality, evidence-based orthopaedic care relies on the generation and translation of robust research evidence. The Fragility Index is a novel method for evaluating the robustness of statistically significant findings from randomized controlled trials (RCTs). It is defined as the minimum number of patients in 1 arm of a trial that would have to change status from a nonevent to an event to alter the results of the trial from statistically significant to nonsignificant.Purpose:To calculate the Fragility Index of statistically significant results from clinical trials in sports medicine and arthroscopic surgery to characterize the robustness of the RCTs in these fields.Methods:A search was conducted in Medline, EMBASE, and PubMed for RCTs related to sports medicine and arthroscopic surgery from January 1, 2005, to October 30, 2015. Two reviewers independently assessed titles and abstracts for study eligibility, performed data extraction, and assessed risk of bias. The Fragility Index was calculated using the Fisher exact test for all statistically significant dichotomous outcomes from parallel-group RCTs. Bivariate correlation was performed to evaluate associations between the Fragility Index and trial characteristics.Results:A total of 48 RCTs were included. The median sample size was 64 (interquartile range [IQR], 48.5-89.5), and the median total number of outcome events was 19 (IQR, 10-27). The median Fragility Index was 2 (IQR, 1-2.8), meaning that changing 2 patients from a nonevent to an event in the treatment arm changed the result to a statistically nonsignificant result, or P ≥ .05.Conclusion:Most statistically significant RCTs in sports medicine and arthroscopic surgery are not robust because their statistical significance can be reversed by changing the outcome status on only a few patients in 1 treatment group. Future work is required to determine whether routine reporting of the Fragility Index enhances clinicians’ ability to detect trial results that should be viewed cautiously.

Background: Low serum 25-hydroxyvitamin D (25(OH)D) levels have been associated with stress fractures in various physically active populations such as the military. Purpose: To examine the association between serum 25(OH)D levels and stress fractures in the military. Study Design: Systematic review and meta-analysis. Methods: Relevant studies were identified through searching multiple databases and manually screening reference lists. Two reviewers independently selected the included studies by applying the eligibility criteria to the title, abstract, and/or full text of the articles yielded in the search. Two reviewers also independently conducted the methodological quality assessment and data extraction. A random-effects model was used to calculate the mean difference (MD) with 95% CI in serum 25(OH)D levels between stress fracture cases and controls. Results: Nine observational studies on lower extremity stress fractures were eligible, and 1 was excluded due to inadequate data. A total of 2634 military personnel (age, 18-30 years; 44% male) with 761 cases (16% male) and 1873 controls (61% male) from 8 studies were included in the analysis. Three of the 8 studies measured serum 25(OH)D levels at the time of stress fracture diagnosis, and the 5 remaining studies measured serum 25(OH)D levels at the time of entry into basic training. The mean serum 25(OH)D level was lower in stress fracture cases than in controls at the time of entry into basic training (MD, −2.63 ng/mL; 95% CI, –5.80 to 0.54; P = .10; I2 = 65%) and at the time of stress fracture diagnosis (MD, −2.26 ng/mL; 95% CI, −3.89 to −0.63; P = .007; I2 = 42%). Conclusion: Despite the inherent limitations of the included studies, the study results suggest some association between low serum 25(OH)D levels and lower extremity stress fractures in military personnel. Given the rigorous training of military personnel, implementing strategies to ensure sufficient 25(OH)D levels may be beneficial for reducing the risk of stress fractures.