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Introduction: Dysbaric osteonecrosis (DON) in people working under increased atmospheric pressure is well documented. It is generally less common in military and commercial divers than in caisson workers, except in some high-risk groups, such as in many indigenous diving industries where workers have little or no understanding of decompression principles. With the increasing popularity within the recreational diving community of deep air and mixed-gas decompression diving (‘technical diving’), it is likely that diving physicians may see an increase in the prevalence of DON in this group in the future. Methods: The case report is presented of a technical diving instructor, with a 30-year history of deep diving, who developed bilateral humeral head DON and required a right shoulder hemi-arthroplasty. A focused literature search was also undertaken to identify published cases of DON in recreational divers. Results: The frequency, duration and depth of exposure to pressure, inadequate decompression, the occurrence of DCS and increasing age have been common features associated with DON in both divers and caisson workers. Many of these features were present in this technical diver. Conclusions: Whilst DON is uncommon in recreational air scuba divers, all the above risk factors are present to a greater degree in technical diving. It is suggested that medical review for DON is merited from time to time in this potentially high-risk group of recreational divers.

INTRODUCTION: Dysbaric osteonecrosis, albeit rare, have been reported in patients with decompression sickness. We report a patient with dysbaric osteonecrosis, diagnosed 60 days after presenting with decompression sickness. CASE PRESENTATION: A 38-year-old, previously fit and healthy male, noted his tank running out of air at approximately 40–50 m while diving, surfaced rapidly before losing consciousness. Upon gaining consciousness, he noted loss of power on all four limbs. He completed 26 sessions of hyperbaric oxygen treatment. Magnetic resonance (MR) of the spine noted T2 abnormality in the upper cervical spine, with some involvement of the central grey matter and the remainder of the cord. According to the International Standards for Neurological Classification of Spinal Cord Injury, it was noted clinically that the patient had a T9 neurological level with ASIA impairment scale A. MR imaging (MRI) of the shoulder was performed, 60 days since initial presentation, after the patient complained of shoulder pain, noted non-specific subcortical oedema of the humeral head, which suggested early osteonecrosis. DISCUSSION: Dysbaric osteonecrosis is rare but remains extremely important to be recognised as a potential complication from decompressive sickness. The increased risk of pathological fractures with dysbaric osteonecrosis plays an important role as it may alter the rehabilitation prescription. One of the unique features of this case, apart from its rarity, was that it was diagnosed 60 days from his initial presentation, when he has passed his acute phase of illness.

Introduction: Dysbaric osteonecrosis (DON) is a specific type of atraumatic osteonecrosis that has been shown to occur mainly in deep-sea divers and workers exposed to increased air pressure environments. The pathophysiology is not entirely understood but is thought to be due to subclinical decompression sickness resulting in arterial gas emboli. This leads to vascular occlusion and subsequent bone death. Case Report: An active 56-year-old male diver presented with progressive bilateral shoulder pain and dysfunction due to bilateral DON of the humeral head and associated posterosuperior rotator cuff tearing. The diagnosis was confirmed by physical examination, X-rays, and magnetic resonance imaging. Due to failure of conservative treatment, a single-stage bilateral, subscapularis-sparing, stemless shoulder hemiarthroplasty with concomitant rotator cuff repair was performed. At 24-month follow-up, the patient showed satisfactory functional outcomes in both shoulders without complication. Conclusion: This single-stage surgical treatment is an exceptional indication for a bilateral dysbaric humeral head osteonecrosis that can be considered in selected cases because may reduce the total recovery time and can be safe and effective at 24 months postoperatively. Keywords: Dysbaric osteonecrosis, humeral head, rotator cuff.

Diving as a method of fishing is used worldwide in small-scale fisheries. However, one of the main causes of morbidity and mortality among fishermen is decompression sickness (DCS). We report the case of a 46-year-old male fisherman diver who presented with chronic inguinal pain that radiated to the lower left limb. Living and working in a fishing port in Yucatan, he had a prior history of DCS. A diagnosis of avascular necrosis in the left femoral head secondary to DCS was made via analysis of clinical and radiological findings. The necrosis was surgically resolved by a total hip arthroplasty. Dysbaric osteonecrosis is a more probable diagnosis. In this region fishermen undergo significant decompression stress in their daily fishing efforts. Further studies regarding prevalence of dysbaric osteonecrosis among small-scale fisheries divers are needed. In a community where DCS is endemic and has become an epidemic, as of late, the perception of this health risk remains low. Furthermore, training and decompression technique are lacking among the fishing communities.

A 26-y-old experienced scotoma scintillans after 59 min of scuba diving at a maximum depth of 26 m. After the patient smoked a cigarette, the scotoma scintillans ceased. However, he then developed a headache, general fatigue, and shoulder and elbow pain. He therefore called an ambulance. Based on the rules of the medical cooperative system for decompression sickness in Izu Peninsula, the fire department called a physician-staffed helicopter. After a physician checked the patient, his complaints remained aside from a low-grade fever. A portable ultrasound revealed bubbles in his inferior vena cava. Because of the risk of his being infected with COVID-19, he was transported to our hospital not by air evacuation but via ground ambulance staff while receiving a drip infusion of fluid and oxygen. After arriving at the hospital, his symptoms had almost subsided. Whole-body computed tomography revealed gas around the bladder, left hip, right knee, bilateral shoulder, joints, and right intramedullary humerus. The patient received high-concentration oxygen, infusion therapy, and observational admission. On the second day of admission, his symptoms had completely disappeared, and he was discharged. To our knowledge, this is the first report that computed tomography might be useful for detecting gas in multiple joints, suggesting the onset of decompression sickness after diving. This might be the first report of gas in an intramedullary space after diving as a potential cause of dysbaric osteonecrosis.

BACKGROUND: Ischemia before the development of dysbaric osteonecrosis (DON) in femoral heads has never been investigated. We assessed whether quantitative magnetic resonance spectroscopy (MRS) and diffusion weighted imaging (DWI) could detect dysbaric changes in divers with hip pain. METHODS: This IRB-approved exploratory study recruited 17 divers [9 with hip pain (Group 1); 8 asymptomatic (Group 2)] with normal findings on radiographs and conventional magnetic resonance imaging scans were age-, gender- and body-mass-index matched to 17 non-divers as controls (Group 1C, 2C). Apparent diffusion coefficients (ADCs) and MRS spectra were obtained from regions/voxels of interest on the femoral heads of all subjects. LCModel was used to determine water content, lipid composition, and the unsaturation index in bone marrow. Mann-Whitney non-parametric test was used to compare results of quantitative MRS and ADCs of ipsilateral femoral heads between divers and controls. RESULTS: MRS of the ipsilateral femoral heads revealed higher water (peak: 4.7 ppm) content, lower total lipid fraction (TLF), and higher unsaturation index (UI) of lipids in Group 1 than in Group 2 (water: P=0.040; UI: P=0.022) and Group 1C (water: P=0.027; TLF: P=0.039; UI: P=0.009). In contrast, femoral head ADCs were comparable between divers and controls. Five out of nine symptomatic divers were contacted for follow-up MRS and DWI studies, and the mean difference in water content in the femoral heads of patients with osteonecrosis was also higher than that in patients with symptom relief (osteonecrosis: 0.077±0.130 vs. symptom relief: 0.003±0.010). CONCLUSIONS: Dysbaric change in the femoral heads of divers with hip pain can be detected using quantitative MRS, which reveals increases in water content and UI of lipids, and a decrease in TLF.

Popa D, Medak A, Chin W, Huchim-Lara O, Fliszar E, Hughes T, Grover I. Dysbaric osteonecrosis (DON) among the artisanal diving fishermen of Yucatán, Mexico. Diving and Hyperbaric Medicine. 2020 December 20;50(4):391–398. doi: 10.28920/dhm50.4.391-398. PMID: 33325021.) Introduction: Artisanal diving fishermen in Yucatán, Mexico have high rates of decompression sickness as a result of frequently unsafe diving practices with surface supplied compressed air. In this study, we investigated the prevalence of dysbaric osteonecrosis (DON), a type of avascular necrosis, in the most susceptible joints in a cohort of these fishermen. Methods: We performed radiographs of bilateral shoulders, hips, and knees of 39 fishermen in Mexico and surveyed them about their medical and diving histories. We performed pairwise correlations to examine if the fishermen’s diving behaviours affected the numbers of joints with DON. Results: The radiographs revealed Grade II or higher DON in 30/39 (76.9%) of the fishermen. Twenty-two of 39 fishermen (56.4%) had at least two affected joints. The number of joints with DON positively correlates with the lifetime maximum diving depth and average bottom time. Conclusions: These findings represent among the highest prevalence rates of DON in divers and reflect the wide-spread scale of decompression sickness among these fishermen. Through this work, we hope to further educate the fishermen on the sequelae of their diving with the aim of improving their diving safety.

Background: Inside attendants working in hyperbaric chambers are exposed to risks related to the hyperbaric environment, handling and care. The aim of this study is to review the literature focusing on the impact of this activity on health. Materials and methods: This is a literature review using the Medline database. Results: Eight articles studied decompression illness (DCI). The incidence of DCI ranged from 0 to 37 per 100,000 sessions in hyperbaric chambers (SHC). The incidence of injuries ranged from 0 to 412 per 100,000 SHC. The most prevalent cause of accidental death was fire: 77 deaths (patients and attendants) between 1923 and 1996. Dysbaric osteonecrosis has been reported in one study only. Conclusions: Inside attendants face risks in the chamber, even if serious health effects seems rare compared to the total number of SHC.

Dysbaric osteonecrosis (DON) is caused by inadequate decompression after exposure to very high ambient air pressures. Different pathological events have been shown to occur in conjunction to result in DON. New observations from clinical and experimental data in this field have led investigators to reformat the etiology, pathogenesis and modify existing modalities of treatment of DON. This short review revisits concepts related to pathophysiology of DON occurring as a part of generalized decompression sickness and discusses newer therapeutic insights stemming from recent advancements in DON research.Bangladesh Soc Physiol. 2015, December; 10(2): 76-81

ResumenObjetivoDescribir osteonecrosis disbárica (ODB) en buzo pesquero y exponer la experiencia inédita de tratamiento con artroplastia de superficie (AS).IntroducciónODB, forma de necrosis avascular secundaria a enfermedad por descompresión (EDC), cuyo tratamiento gold standard para estadios avanzados continúa siendo la artroplastia total (AT).Presentación de casoPaciente de 49 años, buzo pesquero, antecedentes de EDC tratada el 2008 en cámara hiperbárica, con diagnóstico compatible con ODB de cabeza humeral derecha de 6 años de evolución; Constant score=29. Se realiza AS del hombro derecho, y luego de 18 meses de seguimiento se reporta una adecuada evolución clínica con remisión de la sintomatología; Constant score a 18 meses=72.DiscusiónEl uso de AT en el paciente joven es limitado, por lo que surge la necesidad de implementar nuevas técnicas quirúrgicas en este grupo de pacientes.ConclusiónLa AS constituye una alternativa terapéutica en adultos jóvenes y activos con ODB.AbstractObjectiveIntroduce and describe Dysbaric Osteonecrosis (DON) in a fishing diver patient, emphasising clinical features, use of imaging methods, and present a new experience of treatment with Resurfacing Arthroplasty (RA).IntroductionDON, a form of avascular necrosis secondary to Decompression Sickness (DCS). Total Arthroplasty (AT) remains the reference treatment for advanced stages.Case reportMale, 49 years old, fishing diver, with a history of DCS treated in a hyperbaric chamber (2008). Right humeral head DON Compatible with 6 years of onset. Constant Score=29. RA performed on right shoulder. Clinical remission of symptoms was observed after 18 months of follow-up. Constant Score at 18 months=72.DiscussionTA use in young patients is limited, so there is a need to implement new surgical techniques in this group of patients.ConclusionRA is a therapeutic alternative in young and active subjects with DON.

The vascularity-related bone disorders of bone scintigraphic concern include avascular osteonecrosis, bone infarction, dysbaric osteonecrosis, hyperemic and congestive osteoporosis, congestive periostitis, and periostitis of Burger’s disease. The bone scan augmented with nuclear angiography and pinhole technique appears to be the method of choice in these conditions because scintigraphy is not only sensitive and often specific but also panoramic, noninvasive, and easily repeatable in a day or two when necessary. In particular, pinhole scintigraphy has been valued for its usefulness in the preradiographic detection of avascularity and subsequently for the assessment of revascularization. The study can also depict the peculiar tracer uptake in regional osteoporosis as well as in the periostitis associated with the anoxia in the venous stagnation and arteritis obliterans (Burger’s disease).

A 32 year old professional diver presented with a six month history of arthralgia in the lower limbs, right shoulder, and elbow. He had undertaken 3000 dives at a depth greater …

Dysbaric osteonecrosis (DON) usually occurs in professional divers or compressed air workers exposed to iterative high ambient pressure, but has also been reported to occur in recreational scuba divers. In certain circumstances, DON can be considered as a late manifestation of a previous musculoskeletal decompression sickness (DCS) or ‘‘the bends’’ (historically, type 1 DCS). However, despite the observed link between the two illnesses, their correlation remains controversial. There is a general consensus that gas bubble formation during decompression is the primary cause of DCS and DON. Most hypotheses focus on an autochthonous bubble mechanism but there is no agreement on the actual site as far as DCS development is concerned, and it is unclear where, or how bubbles form in the bone marrow cavity causing DON. Magnetic resonance imaging (MRI) is a wellestablished technique to diagnose osteonecrotic lesions. However, there are no specific signs on MRI to correlate the dysbaric origin to osteonecrosis, except the patient’s medical history. In this paper, we present two cases of musculoskeletal DCS in recreational scuba divers with DON complications with initial MRI detection of microaeric cavities in the fatty bone marrow, highly consistent with bubble formation. To our knowledge, these MRI findings compatible with bubble-induced

Introduction: Dysbaric osteonecrosis (DON) is a type of aseptic bone necrosis of long bones such as the humerus, femur, and tibia. It is observed in workers who perform in high-pressure environments. Methods: There were 58 volunteer divers included in this study who had performed at least 500 dives, were working as a dive master or instructor, had never performed industrial and commercial dives, and did not have a diagnosis of osteonecrosis. Radiological evaluation was performed according to the guidelines suggested by The British Research Council Decompression Sickness Panel. A total of eight X-rays were taken per patient. When suspicious lesions were detected, MRI of the region was performed. Results: Of the 58 divers, 2 were eliminated because of inadequate X-ray studies. A total of 18 DON lesions were detected in 14 of 56 (25%) divers. Age was the only variable independently associated with the development of DON (P < 0.05). Discussion: The DON prevalence of 25% in this study is high considering the dive instructors had thorough diving training and strictly practiced the decompression rules. We believe this high prevalence is a result of frequent and sometimes deep dives for many years. Our findings raise the question of whether these divers can be seen as "sports divers" or should be seen as "occupational divers." If the latter description is approved, dive masters and instructors should be kept under periodic screening for DON lesions just like professional commercial divers to help reduce the morbidity associated with this disease.

Joint Bone Spine - In Press.Proof corrected by the author Available online since jeudi 8 octobre 2015

Objectives. Dysbaric osteonecrosis (DON) is a complication of ineffective decompression following exposure to high-pressure environments. This study was designed to determine risk factors for the occurrence of DON in divers. Methods. Fifty-six male divers received skeletal examinations by radiography to assess the occurrence of DON. A questionnaire was used to obtain clinical and diving information, including diving experience and maximum diving depth. Blood samples were collected to analyse the levels of plasminogen activator inhibitor (PAI)-1, cholesterol, triglyceride, lowdensity lipoprotein, very low-density lipoprotein, high-density lipoprotein, apolipoprotein A1 and apolipoprotein B. Results. Lesions of DON were detected in 31 of the 56 (55%) divers. Multivariate logistic regression analysis showed that high levels of PAI-1, a coagulation marker (odds ratio 4.281; P^0.0296) and great maximum diving depth (odds ratio 5.627; P^0.0231) were independent predictors of DON. Conclusions. This study has shown the presence of coagulation abnormality in divers with DON. This result suggests that a pharmacological approach incorporating the use of an anticoagulant may represent a potential strategy for the prevention of DON.

Resume Introduction. – L'osteonecrose dysbarique est une pathologie osseuse rare qui touche essentiellement les plongeurs professionnels et les travailleurs en milieu hyperbare. La correlation avec un accident de decompression osteomyoarticulaire anterieur reste un sujet controverse et le potentiel evolutif des lesions ischemiques depistees par IRM apres un accident dysbarique aigu n'est pas etabli. Exegese. – Les auteurs rapportent l'observation d'un plongeur militaire classe inapte definitif a la plongee sous-marine apres la decouverte radiologique d'une osteonecrose dysbarique evoluee de l'epaule, huit mois apres la survenue d'un accident de decompression au niveau de la meme region articulaire, malgre un traitement par oxygenotherapie hyperbare. L'existence d'un lien etroit entre ces deux evenements et l'importance de ne pas negliger le suivi d'un accident de decompression sont discutes. Conclusion. – Tout accident de decompression a symptomatologie osteomyoarticulaire devrait beneficier precocement d'une exploration par IRM pour depister des lesions de remaniements osteomedullaires susceptibles de s'aggraver ulterieurement en plongee et d'evoluer secondairement vers la necrose osseuse.

Recreational scuba diving has continued to grow in popularity in the past several decades, and military diving remains an integral part of ship husbandry, explosives and ordinance disposal, and special warfare. Although relatively uncommon, disorders such as decompression sickness and arterial gas embolism can be fatal, whereas disorders such as ear barotrauma and dysbaric osteonecrosis are not fatal but can cause significant morbidity. An extensive literature search was performed to comprehensively examine the current role of diagnostic radiology with respect to diving medicine. In selected cases, diagnostic imaging can be of potential benefit for evaluation. Diagnostic imaging plays a useful role in the screening of certain individuals for future fitness to dive. Radiological imaging has also been of paramount importance in postmortem evaluation of dive casualties.

This was a controlled cross-sectional study to investigate the prevalence of dysbaric osteonecrosis (DON) in military divers. MRI examinations of the large joints and adjacent bones were performed in a cross-sectional group of 32 highly experienced military divers and 28 non-divers matched for age and anthropometric data. Additional plain radiographs and follow-up controls were performed in all persons with signs certain or suspicious of DON. In two subject groups (one of divers and one of non-divers), lesions characteristic of DON were detected. From this controlled study, it may be concluded that MRI is a highly sensitive method to detect signs of osteonecrosis. It could be shown that the prevalence of bone lesions characteristic of osteonecrosis in highly experienced military divers is not higher than in non-diving subjects of comparable age. The outcome of this comparably small study group fits to the results of previous extensive studies performed with radiographs. The detected low incidence of DON in this collective may be due to the fact that military divers follow stricter selection criteria, decompression schemes and medical surveillance than commercial divers.

Chennai metropolis has been growing rapidly. Need was felt of a metro rail system. Two corridors were planned. Corridor 1, of 23 km starting from Washermanpet to Airport. 14.3 km of this would be underground. Corridor 2, of 22 km starting from Chennai Central Railway station to St. Thomas Mount. 9.7 km of this would be underground. Occupational health centre's role involved selection of miners and assessing their fitness to work under compressed air. Planning and execution of compression and decompression, health monitoring and treatment of compression related illnesses. More than thirty five thousand man hours of work was carried out under compressed air pressure ranged from 1.2 to 1.9 bar absolute. There were only three cases of pain only ( Type I) decompression sickness which were treated with recompression. Vigilant medical supervision, experienced lock operators and reduced working hours under pressure because of inclement environmental conditions viz. high temperature and humidity, has helped achieve this low incident. Tunnelling activity will increase in India as more cities will soon opt for underground metro railway. Indian standard IS 4138 – 1977 ” Safety code for working in compressed air” needs to be updated urgently keeping pace with modern working methods.

Introduction Due to the increasing popularity in recreational diving long-term health consequences of this sport have aroused interest in the diving community. Although not as important as dysbaric osteonecrosis, ischemic brain lesions, or neurophysiological symptoms, paranasal sinus mucosal hypertrophy (PSMH) has also been discussed as being more prevalent among divers. In this study, we used magnetic resonance imaging (MRI) to compare asymptomatic divers with control subjects for PSMH. Methods We enrolled 79 male divers (34.0 +/- 5.7 yr) and 79 nondiving age- and sex-matched controls (33.8 +/- 6.1 yr). We used a questionnaire to elicit diving history. Divers with a history of sinus barotrauma, subjects with a history of chronic sinusitis or nasal allergies, and those with retention cysts, nasal polyps, or mastoiditis were excluded. T1-, T2-weighted axial and coronal images of the paranasal sinuses were taken with a 1.5-T MRI device. The threshold for PSMH was defined as mucosal thickness above 3 mm. Results MRI revealed PSMH in 33 (41.8%) divers and 18 (22.8%) controls. There were no significant differences between the groups with respect to age, smoking history, or alcohol consumption. PSMH identified in divers did not show an association with age or diving history. Discussion The higher rate of PSMH identified in divers suggests that diving may cause changes in the paranasal sinus mucosa.

Objective To perform a general literature review of dysbaric osteonecrosis (DON) to describe its pathophysiology, prevalence in scuba divers, prognosis, and treatment options. Data sources A literature search on PubMed was performed using the term "dysbaric osteonecrosis" yielding 67 results. There was no exclusion based on dates. Articles that mainly dealt with decompression sickness secondary to tunnel work, mining, or airplane travel were not selected. An additional search on PubMed using the terms "(osteonecrosis diving) NOT dysbaric" was performed to identify other publications not picked up in the initial search. Main results Dysbaric osteonecrosis is associated with prolonged hyperbaric exposure and rapid decompression that cause nitrogen bubbles to enter the fatty marrow-containing shafts of long bones leading to reduction in blood flow and subsequent osteonecrosis. Patients may present asymptomatically, and typical radiographic findings of DON include: decalcification of bone, cystic lesions, osteosclerotic patterns, nontraumatic fractures, bone islands, and a subchondral crescent sign. Surgical treatment options are comprised of core decompression and free vascularized fibular graft, whereas nonsurgical treatment options consist of monitoring, physical therapy, and bisphosphonate therapy. Conclusions Although the incidence of DON has decreased significantly over the past 2 decades, the lack of timely diagnosis and optimal management keeps DON relevant in the orthopedic and sport medicine community.

Dysbaric osteonecrosis is associated with exposure to large ambient pressure changes, and comprises necrotic lesions in the fatty marrow-containing shafts of the long bones, and the ball and socket joints (hips and shoulders). The fundamental causes are still in question and the illness remains a significant health hazard. Radiological and pathological features of both dysbaric and non-dysbaric osteonecrosis are indistinguishable and both are characterized by intramedullary venous stasis, ischemia and necrosis of bone. It has been generally accepted that gas bubbles (probably by initiating intramedullary venous stasis) are the prime cause of dysbaric osteonecrosis, as well as being responsible for Type 1 Decompression Sickness or 'the bends'. Importantly, however, not all series have found a correlation between dysbaric osteonecrosis and 'the bends'. Thus even though it is likely that gas bubbles remain the prime cause of dysbaric osteonecrosis, workers have proposed that in some cases there is another etiological factor which may exaggerate the pathologic effects of gas bubbles, making the bone more susceptible to necrosis. It is proposed that rapid compression by impeding venous drainage from bone initiates intramedullary venous stasis. In the presence of intramedullary gas bubbles, this may progress to thrombosis, ischemia and bone necrosis. The review offers an explanation for total sparing of the knee joint in dysbaric osteonecrosis, and sole involvement of the hip and shoulder (in terms of sub-articular lesions and subsequent joint collapse). In addition to continued observance of proper decompression procedures, a slower rate of compression may further reduce the incidence of dysbaric osteonecrosis. Bone death or osteonecrosis is a concept which Hippocrates put forward in antiquity (1), but it was not until 1794 that James Russell of Edinburgh wrote the first modern-day descriptions. In these cases infection was the predominant etiology (1,2). In 1888 Konig described necrosis of the adult femoral head without infection (3) (aseptic necrosis of bone) and in the same year Twynam reported a case of osteonecrosis in a caisson worker (4) in which there was still a significant infective component. In 1911 Bornstein and Plate, followed later and independently by Bassoe in 1913, presented radiological confirmation of aseptic necrosis of bone in compressed air workers (5). The first report of aseptic necrosis in an underwater diver subsequently appeared in 1936 (6). The condition of aseptic necrosis of bone in association with exposure to raised ambient pressure (previously referred to as caisson disease, pressure-induced osteoarthropathy (7), 'bone rot' (8) and other synonyms (6)) is now generally known as dysbaric osteonecrosis (6). Despite detailed examination of this problem by many authorities, dysbaric osteonecrosis still remains a significant occupational hazard with serious medico-legal consequences (5-13). This suggests that preventative measures are being based upon an incomplete understanding of the pathophysiology of the disease, and that other etiological factors are perhaps being overlooked.