Men and women undergoing total hip arthroplasty have different clinical presentations before surgery and different outcomes at 1-year follow-up.

PURPOSE: The purpose of this study was to investigate the influence of sex on patients undergoing total hip arthroplasty (THA) for hip osteoarthritis (HOA), aiming to assess the clinical and functional outcomes using patient-reported outcome measures (PROMs). METHODS: A retrospective analysis of patients undergoing THA at Ospedale Galeazzi-Sant'Ambrogio between 2016 and 2022 was conducted. Inclusion criteria encompassed Kellgren-Lawrence grade III or IV HOA, with preoperative and 12-month postoperative PROMs. Enroled patients have been selected from a larger cohort without matching design for confounders. The analyses were performed using R software v4.0.3 (R Core Team) and data distributions were assessed using the Shapiro-Wilk normality test. RESULTS: One hundred ninety patients (72 male and 118 female) who had both preoperative and postoperative PROMs have been analysed from our institutional prosthesis registry (Datareg). Baseline and 12-month post-THA PROMs showed significant improvements overall. VAS score dropped notably from baseline to 3 months postsurgery (7.1 ± 2.1 vs. 0.9 ± 1.7). Functional and mental PROMs, including Harris Hip Score-functional (HHS-F), Harris Hip Score-total (HHS-t), SF-12PS and SF-12MS, exhibited substantial improvements post-THA. Stratifying by sex, males had lower baseline VAS, higher HHS-F, SF-12MS and hip disability and osteoarthritis outcome score-physical function short form (HOOS-PS). At 12 months, males displayed significantly better VAS, HHS-F, SF-12PS and HOOS-PS scores. Complication rates were minimal (1.5%), with stable rates across genders, mostly involving dislocation and periprosthetic fractures. Implant survival at 12 months reached an impressive 99%. CONCLUSION: THA remains an effective treatment for severe HOA. However, females presented with worse baseline conditions and showed relatively less improvement at 1-year postsurgery compared to males. This difference could be attributed to physiological and psychosocial factors associated with sex, including hormonal changes, muscle mass decline and perception of pain. Longer follow-ups and prospective studies are necessary to validate these findings and facilitate personalised approaches in HOA treatment, emphasising the need for careful consideration of sex-related variables in clinical decision-making for THA patients. LEVEL OF EVIDENCE: Level III.

A high level of scientific evidence is available to guide treatment of primary shoulder stiffness: The SIAGASCOT consensus.

PURPOSE: Shoulder stiffness (SS) is a condition characterised by active and passive restricted glenohumeral range of motion, which can occur spontaneously in an idiopathic manner or be associated with a known underlying aetiology. Several treatment options are available and currently no consensus has been obtained on which treatment algorithm represents the best choice for the patient. Herein we present the results of a national consensus on the treatment of primary SS. METHODS: The project followed the modified Delphi consensus process, involving a steering, a rating and a peer-review group. Sixteen questions were generated and subsequently answered by the steering group after a thorough literature search. A rating group composed by professionals specialised in the diagnosis and treatment of shoulder pathologies rated the question-answer sets according to the scientific evidence and their clinical experience. RESULTS: Recommendations were rated with an average of 8.4 points out of maximum 9 points. None of the 16 answers received a rating of less than 8 and all the answers were considered as appropriate. The majority of responses were assessed as Grade A, signifying a substantial availability of scientific evidence to guide treatment and support recommendations encompassing diagnostics, physiotherapy, electrophysical agents, oral and injective medical therapies, as well as surgical interventions for primary SS. CONCLUSIONS: A consensus regarding the conservative and surgical treatment of primary SS could be achieved at a national level. This consensus sets basis for evidence-based clinical practice in the management of primary SS and can serve as a model for similar initiatives and adaptable guidelines in other European countries and potentially on a global scale. LEVEL OF EVIDENCE: Level I.

Photosealed Neurorrhaphy Using Autologous Tissue.

Photochemical sealing of a nerve wrap over the repair site isolates and optimizes the regenerating nerve microenvironment. To facilitate clinical adoption of the technology, we investigated photosealed autologous tissue in a rodent sciatic nerve transection and repair model. Rats underwent transection of the sciatic nerve with repair performed in three groups: standard microsurgical neurorrhaphy (SN) and photochemical sealing with a crosslinked human amnion (xHAM) or autologous vein. Functional recovery was assessed at four-week intervals using footprint analysis. Gastrocnemius muscle mass preservation, histology, and nerve histomorphometry were evaluated at 120 days. Nerves treated with a PTB-sealed autologous vein improved functional recovery at 120 days although the comparison between groups was not significantly different (SN: -58.4 +/- 10.9; XHAM: -57.9 +/- 8.7; Vein: -52.4 +/- 17.1). Good muscle mass preservation was observed in all groups, with no statistical differences between groups (SN: 69 +/- 7%; XHAM: 70 +/- 7%; Vein: 70 +/- 7%). Histomorphometry showed good axonal regeneration in all repair techniques. These results demonstrate that peripheral nerve repair using photosealed autologous veins produced regeneration at least equivalent to current gold-standard microsurgery. The use of autologous veins removes costs and foreign body concerns and would be readily available during surgery. This study illustrates a new repair method that could restore normal endoneurial homeostasis with minimal trauma following severe nerve injury.

One-stage vs two-stage bilateral THA in Lombardy: a cost-effectiveness analysis.

BACKGROUND: Total hip arthroplasty (THA) is the most common treatment for primary and secondary end-stage hip osteoarthritis (OA). Almost 20% of all patients undergoing primary THA suffer from bilateral hip OA and, consequently, will need a contralateral procedure to be performed in the following years. The aim of this study is to evaluate the cost-effectiveness and the reliability of one-stage bilateral THA (1-BTHA) compared to two-stage bilateral THA (2-BTHA), in low-risk patients, performed with anterior minimally invasive surgery (AMIS). METHODS: Single patient's costs were obtained by dividing the annual costs report by the number of hospitalizations, considering the diagnosis related group (DRG) of the two procedures. Then, 16 patients undergoing 1-BTHA and 8 undergoing 2-BTHA were examined. Hemoglobin (Hb) values before surgery and before discharge, transfusion rate and the occurrence of post-operative complications were observed. RESULTS: Procedural costs were divided in different subgroups: pre-hospitalization, operating room, hospital stay, post-operative follow-up and other costs. 1-BTHA total costs amount to 5.754,82€, while performing 2-BTHA costs 7.624,32€. However, considering DRG reimbursement, the hospital's profit margin following 1-BTHA is lower than that following 2-BTHA (6.346,18€ versus 9.261,68€). Surgical time was found not to be significantly different between 1-BTHA and 2-BTHA (141,13 ± 26,1 min vs 164,8 ± 44,3 min; p = 0,111). The two groups showed a statistically significant difference in Hb decrease (4,8 ± 1,3 g/dl vs 3,3 ± 0,9; p = 0,001), despite no variances in transfusion rate. No further complications were observed in either group. CONCLUSIONS: This study demonstrates how, in carefully selected patients, 1-BTHA performed with AMIS is a cost-effective and safe technique compared to 2-BTHA, resulting in a shorter OR time, LOS and lower overall costs. LEVEL OF EVIDENCE: III.

Micro-fragmented adipose tissue (mFAT) associated with arthroscopic debridement provides functional improvement in knee osteoarthritis: a randomized controlled trial.

PURPOSE: Current conservative treatments for knee OA provide limited benefits, with symptoms relief for a short amount of time. Regenerative medicine approaches such as the use of microfragmented adipose tissue (mFAT) showed promising results in terms of durable effects and the possibility to enhance tissue healing and counteract the progression of the pathology. Nevertheless, up to today, the large part of clinical data about mFAT use refers to uncontrolled studies, especially in the surgical setting. The purpose of this study was to evaluate the effectiveness of mFAT applied in association with arthroscopic debridement (AD) for the treatment of knee OA, in terms of symptoms relief and tissue healing. METHODS: This study is a prospective, randomized controlled clinical trial. 78 patients affected by knee OA grade 3-4 according to KL classification were randomly assigned to AD or AD + mFAT treatment groups. Clinical, radiological and serological assessments were performed at 6 months after treatment. Additional clinical evaluation was performed at the end of the study with an average follow-up of 26.1 ± 9.5 months. VAS, KOOS, WOMAC and SF-12 were also collected at both timepoints, KSS only at 6 months. RESULTS: Treatment with AD + mFAT improved functional scores at both 6 months (KOOS-PS: + 11.7 ± 20.2 vs + 24.4 ± 22.5, in AD and AD + mFAT, respectively, p = 0.024; KSS: + 14.9 ± 15.9 vs + 24.8 ± 23.5, in AD and AD + mFAT, respectively, p = 0.046) and 24-month follow-ups (KOOS-PS Functional subscale: - 2.0 ± 3.5 vs - 4.7 ± 4.2, in AD and AD + mFAT, respectively, p = 0.012). Lower T2-mapping scores were obtained in AD + mFAT-treated group in medial and lateral condyle compartments (p < 0.001). Slight increase was observed in the levels of a serum biomarker of cartilage deposition (PIIINP) in both groups at 6-month follow-up (p = 0.037). CONCLUSION: mFAT improves functional outcome and MRI appearance when used in association with AD, therefore supporting its use in the treatment of knee OA in an arthroscopic setting.

Knee Osteoarthritis: Epidemiology, Pathogenesis, and Mesenchymal Stem Cells: What Else Is New? An Update.

Osteoarthritis (OA) is a chronic disease and the most common orthopedic disorder. A vast majority of the social OA burden is related to hips and knees. The prevalence of knee OA varied across studies and such differences are reflected by the heterogeneity of data reported by studies conducted worldwide. A complete understanding of the pathogenetic mechanisms underlying this pathology is essential. The OA inflammatory process starts in the synovial membrane with the activation of the immune system, involving both humoral and cellular mediators. A crucial role in this process is played by the so-called "damage-associated molecular patterns" (DAMPs). Mesenchymal stem cells (MSCs) may be a promising option among all possible therapeutic options. However, many issues are still debated, such as the best cell source, their nature, and the right amount. Further studies are needed to clarify the remaining doubts. This review provides an overview of the most recent and relevant data on the molecular mechanism of cartilage damage in knee OA, including current therapeutic approaches in regenerative medicine.

The use of electronic PROMs provides same outcomes as paper version in a spine surgery registry. Results from a prospective cohort study.

BACKGROUND AND PURPOSE: Patient-Reported Measured Outcomes (PROMs) are essential to gain a full understanding of a patient's condition, and in spine surgery, these questionnaires are of help when tailoring a surgical strategy. Electronic registries allow for a systematic collection and storage of PROMs, making them readily available for clinical and research purposes. This study aimed to investigate the reliability between the electronic and paper form of ODI (Oswestry Disability Index), SF-36 (Short Form Health Survey 36) and COMI-back (Core Outcome Measures Index for the back) questionnaires. METHODS: A prospective analysis was performed of ODI, SF-36 and COMI-back questionnaires collected in paper and electronic format in two patients' groups: Pre-Operatively (PO) or at follow-up (FU). All patients, in both groups, completed the three questionnaires in paper and electronic form. The correlation between both methods was assessed with the Intraclass Correlation Coefficients (ICC). RESULTS: The data from 100 non-consecutive, volunteer patients with a mean age of 55.6 ± 15.0 years were analysed. For all of the three PROMs, the reliability between paper and electronic questionnaires results was excellent (ICC: ODI = 0.96; COMI = 0.98; SF36-MCS = 0.98; SF36-PCS = 0.98. For all p < 0.001). CONCLUSIONS: This study proved an excellent reliability between the electronic and paper versions of ODI, SF-36 and COMI-back questionnaires collected using a spine registry. This validation paves the way for stronger widespread use of electronic PROMs. They offer numerous advantages in terms of accessibility, storage, and data analysis compared to paper questionnaires.

Direct superior approach versus posterolateral approach in total hip arthroplasty: a randomized controlled trial on early outcomes on gait, risk of fall, clinical and self-reported measurements.

Background and purpose - Several surgical approaches are used in primary total hip arthroplasty (THA). In this randomized controlled trial we compared gait, risk of fall, self-reported and clinical measurements between subjects after direct superior approach (DSA) versus posterolateral approach (PL) for THA.Patients and methods - Participants with DSA (n = 22; age 74 [SD 8.9]) and PL (n = 23; age 72 [7.7]) underwent gait analysis, risk of fall assessment and Timed Up and Go Test (TUG) before (PRE), 1 month (T1) and 3 months after (T3) surgery. Data on bleeding and surgical time was collected.Results - DSA resulted in longer surgical times (90 [14] vs. 77 [20] min) but lower blood loss (149 [66] vs. 225 [125] mL) than PL. DSA had lower risk of fall at T3 compared with T1 and higher TUG scores at T3 compared with T1 and PRE. PL improved balance at T3 compared with T1 and PRE. Spatiotemporal gait parameters improved over time for both DSA and PL with no inter-group differences, whereas DSA, regarding hip rotation range of motion, showed lower values at T3 and T1 compared with PRE and, furthermore, this group had lower values at T1 and T3 compared with PL. All foregoing comparisons are statistically signficant (p < 0.05)Interpretation - DSA showed longer surgical time and lower blood loss compared with PL and early improvements in TUG, spatiotemporal, and kinematic gait parameters, highlighting rapid muscle strength recovery.

Therapeutic potential of microRNA in tendon injuries.

INTRODUCTION: The regulatory role of microRNA (miRNA) in several conditions has been studied, but their function in tendon healing remains elusive. This review summarizes how miRNAs are related to the pathogenesis of tendon injuries and highlights their clinical potential, focusing on the issues related to their delivery for clinical purposes. SOURCES OF DATA: We searched multiple databases to perform a systematic review on miRNA in relation to tendon injuries. We included in the present work a total of 15 articles. AREAS OF AGREEMENT: The mechanism of repair of tendon injuries is probably mediated by resident tenocytes. These maintain a fine equilibrium between anabolic and catabolic events of the extracellular matrix. Specific miRNAs regulate cytokine expression and orchestrate proliferation and differentiation of stromal cell lines involved in the composition of the extracellular matrix. AREAS OF CONTROVERSY: The lack of effective delivery systems poses serious obstacles to the clinical translation of these basic science findings. GROWING POINT: In vivo studies should be planned to better explore the relationship between miRNA and tendon injuries and evaluate the most suitable delivery system for these molecules. AREAS TIMELY FOR DEVELOPING RESEARCH: Investigations ex vivo suggest therapeutic opportunities of miRNA for the management of tendon injuries. Given the poor pharmacokinetic properties of miRNAs, these must be delivered by an adequate adjuvant transport system.

Functional and radiological outcome of anterior retroperitoneal versus posterior transforaminal interbody fusion in the management of single-level lumbar degenerative disease.

OBJECTIVE: In this study the authors compared the anterior lumbar interbody fusion (ALIF) and posterior transforaminal lumbar interbody fusion (TLIF) techniques in a homogeneous group of patients affected by single-level L5-S1 degenerative disc disease (DDD) and postdiscectomy syndrome (PDS). The purpose of the study was to analyze perioperative, functional, and radiological data between the two techniques. METHODS: A retrospective analysis of patient data was performed between 2015 and 2018. Patients were clustered into two homogeneous groups (group 1 = ALIF, group 2 = TLIF) according to surgical procedure. A statistical analysis of clinical perioperative and radiological findings was performed to compare the two groups. A senior musculoskeletal radiologist retrospectively revised all radiological images. RESULTS: Seventy-two patients were comparable in terms of demographic features and surgical diagnosis and included in the study, involving 32 (44.4%) male and 40 (55.6%) female patients with an average age of 47.7 years. The mean follow-up duration was 49.7 months. Thirty-six patients (50%) were clustered in group 1, including 31 (86%) with DDD and 5 (14%) with PDS. Thirty-six patients (50%) were clustered in group 2, including 28 (78%) with DDD and 8 (22%) with PDS. A significant reduction in surgical time (107.4 vs 181.1 minutes) and blood loss (188.9 vs 387.1 ml) in group 1 (p < 0.0001) was observed. No significant differences in complications and reoperation rates between the two groups (p = 0.561) was observed. A significant improvement in functional outcome was observed in both groups (p < 0.001), but no significant difference between the two groups was found at the last follow-up. In group 1, a faster median time of return to work (2.4 vs 3.2 months) was recorded. A significant improvement in L5-S1 postoperative lordosis restoration was registered in the ALIF group (9.0 vs 5.0, p = 0.023). CONCLUSIONS: According to these results, interbody fusion is effective in the surgical management of discogenic pain. Even if clinical benefits were achieved earlier in the ALIF group (better scores and faster return to work), both procedures improved functional outcomes at last follow-up. The ALIF group showed significant reduction of blood loss, shorter surgical time, and better segmental lordosis restoration when compared to the TLIF group. No significant differences in postoperative complications were observed between the groups. Based on these results, the ALIF technique enhances radiological outcome improvement in spinopelvic parameters when compared to TLIF in the management of adult patients with L5-S1 DDD.

Orthotopic Bone Formation by Streamlined Engineering and Devitalization of Human Hypertrophic Cartilage.

Most bones of the human body form and heal through endochondral ossification, whereby hypertrophic cartilage (HyC) is formed and subsequently remodeled into bone. We previously demonstrated that HyC can be engineered from human mesenchymal stromal cells (hMSC), and subsequently devitalized by apoptosis induction. The resulting extracellular matrix (ECM) tissue retained osteoinductive properties, leading to ectopic bone formation. In this study, we aimed at engineering and devitalizing upscaled quantities of HyC ECM within a perfusion bioreactor, followed by in vivo assessment in an orthotopic bone repair model. We hypothesized that the devitalized HyC ECM would outperform a clinical product currently used for bone reconstructive surgery. Human MSC were genetically engineered with a gene cassette enabling apoptosis induction upon addition of an adjuvant. Engineered hMSC were seeded, differentiated, and devitalized within a perfusion bioreactor. The resulting HyC ECM was subsequently implanted in a 10-mm rabbit calvarial defect model, with processed human bone (Maxgraft®) as control. Human MSC cultured in the perfusion bioreactor generated a homogenous HyC ECM and were efficiently induced towards apoptosis. Following six weeks of in vivo implantation, microcomputed tomography and histological analyses of the defects revealed an increased bone formation in the defects filled with HyC ECM as compared to Maxgraft®. This work demonstrates the suitability of engineered devitalized HyC ECM as a bone substitute material, with a performance superior to a state-of-the-art commercial graft. Streamlined generation of the devitalized tissue transplant within a perfusion bioreactor is relevant towards standardized and automated manufacturing of a clinical product.

The presence of residents during orthopedic operation exerts no negative influence on outcome.

BACKGROUND: Operative procedural training is a key component of orthopedic surgery residency. It is unclear how and whether residents participation in orthopedic surgical procedures impacts on post-operative outcomes. SOURCES OF DATA: A systematic search was performed to identify articles in which the presence of a resident in the operating room was certified, and was compared with interventions without the presence of residents. AREAS OF AGREEMENT: There is a likely beneficial role of residents in the operating room, and there is only a weak association between the presence of a resident and a worse outcome for orthopedic surgical patients. AREAS OF CONTROVERSY: Most of the studies were undertaken in USA, and this represents a limit from the point of view of comparison with other academic and clinical realities. GROWING POINT: The data provide support for continued and perhaps increased involvement of resident in orthopedic surgery. AREAS OF RESEARCH: To clarify the role of residents on clinically relevant outcomes in orthopedic patients, appropriately powered randomized control trials should be planned.

MicroRNA in osteoarthritis: physiopathology, diagnosis and therapeutic challenge.

BACKGROUND: Osteoarthritis (OA) is the most orthopedic condition. The pattern of gene expression and the transcription factors that exert control of chondrogenesis have been extensively studied. SOURCES OF DATA: A systematic search (up to July 2018) of articles assessing the role of microRNA (miRNA) in physiopathology, diagnosis and therapy of OA was performed, with the purpose of giving a critical perspective of the possibilities for diagnostic and therapeutic use of miRNA in the management of OA. AREAS OF AGREEMENT: miRNAs are small noncoding RNAs that can regulate gene expression in human cells. miRNAs can be expressed in a different fashion in osteoarthritic compared to nonosteoarthritic cartilage. AREAS OF CONTROVERSY: The mechanisms that produce alteration of gene expression in OA are still not completely understood. miRNAs may be involved in the diagnosis of OA as well as in its treatment. GROWING POINTS: There are complex interactions between miRNAs and their multiple target genes. These interactions may be important in gene regulation and the control of homeostatic pathways in OA. AREAS TIMELY FOR DEVELOPING RESEARCH: miRNA could be useful for diagnostic or management purposes, but the issue of delivery of miRNA targeting agents needs to be overcome before miRNA can be applied in clinical practice.

Biological and chemical changes in fluoroquinolone-associated tendinopathies: a systematic review.

INTRODUCTION: The present systematic review investigates the biological and chemical mechanisms that affect the health and structure of tendons following the use of fluoroquinolones (FQs). SOURCES OF DATA: A total of 12 articles were included, organized, and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. AREAS OF AGREEMENT: Five mechanisms were identified: arrest of proliferation through a decreased activity of cyclin B, CDK-1, CHK-1, and increased PK-1; decrease tenocytes migration through decreased phosphorylation of FAK; decrease type I collagen metabolism through increased MMP-2; chelate effect on ions that influence epigenetics and several enzymes; fluoroquinolones-induced ROS (radical oxygen species) production in mitochondria. AREAS OF CONTROVERSY: There is no definite structure-damage relationship. The dose-effect relationship is unclear. GROWING POINTS: Knowing and defining the damage exerted by FQs plays a role in clinical practice, replacing FQs with other antibacterial drugs or using antioxidants to attenuate their pathological effects. AREAS TIMELY FOR DEVELOPING RESEARCH: Clinical and basic sciences studies for each FQs are necessary.

Biomechanical issues of tissue-engineered constructs for articular cartilage regeneration: in vitro and in vivo approaches.

BACKGROUND: Given the limited regenerative capacity of injured articular cartilage, the absence of suitable therapeutic options has encouraged tissue-engineering approaches for its regeneration or replacement. SOURCES OF DATA: Published articles in any language identified in PubMed and Scopus electronic databases up to August 2019 about the in vitro and in vivo properties of cartilage engineered constructs. A total of 64 articles were included following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. AREAS OF AGREEMENT: Regenerated cartilage lacks the biomechanical and biological properties of native articular cartilage. AREAS OF CONTROVERSY: There are many different approaches about the development of the architecture and the composition of the scaffolds. GROWING POINTS: Novel tissue engineering strategies focus on the development of cartilaginous biomimetic materials able to repair cartilage lesions in association to cell, trophic factors and gene therapies. AREAS TIMELY FOR DEVELOPING RESEARCH: A multi-layer design and a zonal organization of the constructs may lead to achieve cartilage regeneration.

Clinical Performance, Patient Reported Outcome, and Radiological Results of a Short, Tapered, Porous, Proximally Coated Cementless Femoral Stem: Results up to Seven Years of Follow-Up.

BACKGROUND: The primary aim of our study was to assess clinical performance, patient reported outcome and radiological results of cementless primary total hip arthroplasty using Tri-Lock Bone Preservation Stem. METHODS: Between March 2010 and June 2012, 163 consecutive patients, were enrolled in the study. Patients were assessed clinically and radiographically prior to surgery as well as at 6, 12, 24 months and then at 5, 6, and 7 years postoperatively. RESULTS: Using the Dorr classification, 39 patients (23.9%) were classified as Dorr A, 116 patients (71.2%) as Dorr B, and 8 patients (4.9%) as Dorr C. A total of 139 patients (85.3%) received a high offset, whereas 24 patients (14.7%) received a standard offset stem. Total Harris Hip Score of the patients increased from a mean of 27.29 (±4.6) preoperatively, upto 97.28 (±9.0) after 5 years. Mean preoperative Short Form-12 (SF-12) Physical Health Composite Scale score was 27.31 (±3.8). After 5 year was 55.3 (34-57). The mean preoperative SF-12 Mental Health Composite Scale score was 57.02 (±5.9). After 5 year was 59.3 (28.7-60.8). Only one patient underwent revision surgery for dislocation and revision of the head. CONCLUSION: Tri-lock Bone Preservation Stem DePuy proved to be an easy-to-use device. Results obtained up to 7 years of FU show excellent clinical performance, as well as radiographic osseointegration, with no cases of aseptic loosening and no images of progressive radiolucent lines or periprosthetic osteolysis.

Thoracic Outlet Syndrome in the Overhead Athlete: A Report of 2 Cases of Subclavius Posticus Muscle.

Subclavius posticus muscle is a supernumerary anatomical variation of the subclavius muscle. The aim of this study was to show the possible contribution of the posticus muscle in the development of unilateral thoracic outlet syndrome (TOS) in overhead athletes, presenting hypertrophy of the dominant arm due to their sport activity. Reported here are 2 young overhead athletes complaining pain, paresthesia, weakness in the dominant upper limb, although presenting none of the main shoulder and neurological disorders. After developing subclavian vein thrombosis, TOS was suspected and finally diagnosed by dynamic magnetic resonance angiography, which also showed bilateral subclavius posticus muscle in both patients. Despite bilateral subclavius posticus, TOS was only evident in the dominant limb in which the association of hypertrophy of lateral cervical muscles, resulting from the overhead sport activity, to the subclavius posticus likely led to a significant reduction of the upper thoracic outlet space.