ACR Appropriateness Criteria Osteonecrosis of the Hip

Canadian Association of Radiologists Musculoskeletal System Diagnostic Imaging Referral Guideline

The Canadian Association of Radiologists (CAR) Musculoskeletal System Expert Panel consists of musculoskeletal radiologists, a family physician, a sports and exercise medicine physician, emergency medicine physicians, a patient advisor, and an epidemiologist/guideline methodologist. After developing a list of 25 musculoskeletal clinical/diagnostic scenarios, a systematic rapid scoping review was undertaken to identify systematically produced referral guidelines that provide recommendations for 1 or more of these clinical/diagnostic scenarios. Recommendations from 41 guidelines (50 publications) and contextualization criteria in the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) for guidelines framework were used to develop 124 recommendation statements across the 25 scenarios related to the evaluation of the musculoskeletal system. This guideline presents the methods of development and the recommendations for imaging in the context of musculoskeletal pain, infection, tumors, arthropathies, metabolic bone disease, stress injuries, orthopedic hardware, avascular necrosis/bone infarction, and complex regional pain syndrome.

Physical therapist awareness of diagnostic imaging referral jurisdictional scope of practice: an observational study

OBJECTIVES

To examine physical therapist awareness and utilization of imaging referral privileges in the United States (US) and how it relates to direct access frequency.

METHODS

This study utilized survey data collected in 2020-2021 from US physical therapists. Subjects were asked about imaging referral jurisdictional authority in their state. Responses were analyzed for accuracy and compared to the level of jurisdictional authority and its impact on imaging referral. Analysis of imaging skills performance and imaging referral practices were compared to direct access frequency.

RESULTS

Only 42.0% of physical therapists practicing in states that allow imaging referral were aware of this privilege. Those practicing where imaging referral was allowed via state legislation were significantly more likely (p < 0.01) to be aware of this privilege (71.4%) compared to those granted by the state board (25.2%). Those aware of their imaging referral scope were more likely (p < 0.01) to practice imaging referral (44.5%) compared to those who were unaware (3.2%). Direct access frequency was positively associated with imaging skill performance and imaging referral practice (p < 0.01). Doctors of Physical Therapy, residency/fellowship-trained physical therapists, and board-certified physical therapists all reported practicing greater frequency of direct access (p < 0.01).

DISCUSSION/CONCLUSION

There is a striking lack of awareness of imaging privileges among physical therapists as influenced by the level of jurisdictional scope. These results suggest that the lack of awareness may have a dampening effect on diagnostic imaging referrals. The American Physical Therapy Association should consider engaging with state boards to raise imaging privilege awareness.

Collapse-related bone changes at multidetector CT in ARCO 1-2 osteonecrotic femoral heads: correlation with clinical and MRI data

OBJECTIVE

To assess the frequency of collapse-related bone changes at multi-detector CT (MDCT) in osteonecrotic femoral heads (ONFH) and to compare clinical parameters and MRI findings in Association Research Circulation Osseous (ARCO) 1-2 ONFH with or without collapse-related bone changes (CRBC) at MDCT.

MATERIALS AND METHODS

This is a secondary analysis of radiographic, MRI, and MDCT examinations of ONFH of patients eligible for a prospective clinical trial. Radiographs and MRI were analyzed to perform ARCO staging. Frequency of CRBC at MDCT including cortical interruption, trabecular interruption, impaction, and resorption was determined by two readers (R1, R2) blinded to radiographic, MRI, and clinical data. Baseline clinical and imaging data of ARCO 1-2 ONFH were compared between hips with or without CRBC at MDCT.

RESULTS

One hundred thirty-two hips of 77 participants were analyzed. There were 78 non-collapsed and 54 collapsed ONFH. For R1 and R2, 31/78 (40%) and 20/78 (26%) ARCO 1-2 ONFH and 54/54 (100%) and 53/54 (98%) ARCO 3-4 ONFH showed at least one CRBC at MDCT. For both readers, there was no significant difference in pain, functional impairment, size of lesion, and the presence of BME on MRI between ARCO 1-2 hips with or without CRBC at MDCT.

CONCLUSION

Twenty-six to forty percent of ARCO 1-2 ONFH demonstrate at least one collapse-related bone change at CT. Their clinical and MRI findings do not differ from those without collapse-related bone changes.

KEY POINTS

• Ninety-eight to one hundred percent of collapsed and 26-40% of non-collapsed osteonecrotic femoral heads presented at least one collapse-related bone change at CT (cortical or trabecular bone interruption, trabecular bone impaction, or resorption). • There was no significant difference in age, sex, pain, functional impairment, size of lesion, or frequency of marrow edema on MRI between non-collapsed hips with or without collapse-related bone changes at CT. • The significance of collapse-related bone changes at CT should be further assessed.

Familial Thrombophilia Is Associated With Primary Multifocal Osteonecrosis: A Case-Control Study of 40 Patients

To characterize pathoetiologic associations of heritable thrombophilia-hypofibrinolysis with idiopathic (primary) multifocal osteonecrosis (ON) (≥3 ON anatomic sites), we prospectively studied 28 women and 12 men with primary multifocal ON compared with 27 women and 24 men with primary nonmultifocal ON (<3 sites) and 110 healthy controls without ON. The 40 cases with primary multifocal ON differed from controls for 3 familial thrombophilias: Factor V Leiden heterozygosity (6 of 40 [15%] vs 2 of 109 [2%], P=.002), G20210A prothrombin gene heterozygosity (6 of 40 [15%] vs 3 of 110 [3%], P=.011), and high (>150%) Factor VIII (8 of 40 [20%] vs 7 of 103 [7%], P=.031). These case-control familial coagulation differences paralleled those in 51 concurrently evaluated cases with primary nonmulti-focal ON, 7 of 51 (14%) of whom had Factor V Leiden heterozygosity vs 2% of controls (P=.005) and 14 of 44 (32%) of whom had high Factor VIII vs 7 of 103 (7%) of controls (P=.0002). Recognition of familial thrombophilia as a common pathoetiology of primary multifocal ON provides an opportunity for early anticoagulation (before joint collapse), allowing both prophylaxis and therapy aimed at relieving pain and slowing or stopping progression of the disease to joint collapse. [Orthopedics. 202X;XX(X):xx-xx.].

Intramedullary core decompression combined with endoscopic intracapsular decompression and debridement for pre-collapse non-traumatic osteonecrosis of the femoral head

BACKGROUND

The effect of core decompression on the treatment of pre-collapse non-traumatic osteonecrosis of the femoral head (ONFH) is still limited. This study aimed to explore the efficacy of core decompression combined with intra-articular decompression (debridement of the hip joint and incision of the hip capsule) under hip arthroscopic guidance in patients with pre-collapse ONFH.

METHODS

The clinical data of 101 patients with pre-collapse ONFH were analysed retrospectively. Sixty patients (80 hips) received small-diameter multi-channel core decompression alone in first half review period (group B). Forty-one patients (59 hips) were treated with small-diameter multi-channel core decompression combined with intra-articular decompression under hip arthroscopy guidance in second half review period (group A). The surgical duration; intraoperative bleeding; intra-articular pressure(IAP) before and after surgery; length of hospital stay; hospitalisation expenses; visual analogue scale (VAS) score before, 1 week, 4 weeks, 3 months and 1 year after surgery; and Harris score of the hip joint before, 3 months and 1 year after surgery were recorded and compared between group A and group B. X-ray examination was performed every month to observe the collapse of the femoral head within 2 years after surgery, which was compared using the Kaplan-Meier survival curve analysis.

RESULTS

When the two groups were compared, the surgical duration was longer and hospitalisation expenses were higher in group A than in group B (P < 0.05). However, the VAS score and the Harris score of the hip joint after surgery improved significantly compared with those before surgery (P < 0.05), which were more apparent in group A than in group B (P < 0.05). X-ray examination revealed that 6 hips in group A and 22 in group B received femoral head collapse at the 2-year follow-up. The survival rate of the femoral head in group A was significantly higher than that in group B (P < 0.05).

CONCLUSION

Small-diameter multi-channel core decompression combined with intra-articular decompression (debridement of the hip joint and incision of the hip capsule) under hip arthroscopic guidance for treating early ONFH can more effectively alleviate joint pain, improve joint function and delay ONFH progression.

Collapse-Related Bone Changes in Osteonecrotic Femoral Heads at Multidetector CT: Comparison between Femoral Heads with Limited and Advanced Collapse

Aim:

To assess the frequency of bone changes in resected osteonecrotic femoral head (ONFH) specimens at multidetector computed tomography (MDCT) and compare their frequencies between ONFH with limited or advanced collapse.

Method:

Fourteen ONFH were imaged using MDCT (n = 14) and microcomputed tomography ([µCT]; n = 8). Preoperative staging was performed using radiographs and MRI. Coronal reformats of MDCT images of the specimens were analyzed using the grid overlay method. There were 2,933 grid boxes containing cortical bone and 10,596 containing trabecular bone. Two MSK radiologists assessed in every grid box the presence of interface-related sclerosis, cortical bone interruption, trabecular bone interruption, and trabecular bone resorption. The frequency of grid boxes with bone changes at MDCT was calculated and compared between ONFH with limited (<1.5 mm) or advanced (≥1.5 mm) collapse.

Results:

For both readers R1 and R2, there were 1111/10596 (10.5%) and 1362/10596 (12.9%) grid boxes with interface-related bone sclerosis, 557/2933 (19%) and 413/2933 (14.1%) with cortical bone interruption, 796/10596 (7.5%) and 665/10596 (6.3%) with trabecular bone interruption, and 331/10596 (3.1%) and 595/10596 (5.6%) with trabecular bone resorption. The frequency of grid boxes with cortical interruption and trabecular bone resorption was significantly higher in ONFH with advanced than in ONFH with limited collapse. There was no significant difference in frequency of grid boxes with trabecular interruption and interface-related bone sclerosis between ONFH with advanced or limited collapse.

Conclusion:

Cortical interruption and trabecular resorption, but not trabecular interruption, were more frequent in osteonecrotic femoral heads with advanced than with limited collapse.

Digital Tomosynthesis versus Conventional Radiography for Evaluating Osteonecrosis of the Femoral Head

Objective

The aim of this study was to compare the diagnostic performances of digital tomosynthesis (DTS) and conventional radiography in detecting osteonecrosis of the femoral head (ONFH) using computed tomography (CT), as the reference standard and evaluate the diagnostic reproducibility of DTS.

Materials and Methods

Forty-five patients (24 male and 21 female; age range, 25–77 years) with clinically suspected ONFH underwent anteroposterior radiography, DTS, and CT. Two musculoskeletal radiologists independently evaluated the presence and type of ONFH. The diagnostic performance of radiography and DTS in detecting the presence of ONFH and determining the types of ONFH were evaluated. The interobserver and intraobserver reliabilities of each imaging modality were analyzed using Cohen's kappa.

Results

DTS had higher sensitivity (89.4%–100% vs. 74.5%–76.6%) and specificity (97.3%–100% vs. 78.4%–83.8%) for ONFH detection than radiography. DTS showed higher performance than radiography in identifying the subtypes of ONFH with statistical significance in one reader (type 1, 100% vs. 30.8%, p = 0.004; type II, 97.1% vs. 73.5%, p = 0.008). The interobserver agreement was excellent for DTS and moderate for radiography (kappa of 0.86 vs. 0.57, respectively). The intraobserver agreement for DTS was higher than that of radiography (kappa of 0.96 vs. 0.69, respectively).

Conclusion

DTS showed higher diagnostic performance and reproducibility than radiography in detecting ONFH. DTS may be used as a first-line diagnostic modality instead of radiography for patients suspected of having ONFH.

Alendronate Alleviated Femoral Head Necrosis and Upregulated BMP2/EIF2AK3/EIF2A/ATF4 Pathway in Liquid Nitrogen Treated Rats

Background

Osteonecrosis of the femoral head (ONFH) seriously affects the quality of life and labor ability of patients. It is urgent and vital to find the methods for necrosis clinical treatment.

Objective

This study aims to study the potential protective effects of Alendronate in the early stage of femur head necrosis.

Methods

Ten clinal ONFH tissue samples were employed. H&E staining was employed for the observation of the pathological characteristics of ONFH. The rat model (n=12) was established by the treatment of liquid nitrogen and then treated with Alendronate. The protein expression of BMP2, EIF2AK3, EIF2A and ATF4 were detected via Western blotting and IHC.

Results

Fibrin and necrotizing granulation tissue were observed in ONFH tissues with lymphocytes and plasma cells infiltrating in the necrotic area, exhibiting the inflammatory muscle with abnormal shape and color. In the Model group, the BMP2 and ATF4 were mainly distributed in the cell boundaries. The relative protein expression of BMP2, EIF2AK3, EIF2A, ATF4 was decreased in the Model group, compared to the NC group, which was partially recovered by the Alendronate application.

Conclusion

Alendronate application partially reversed the suppression of expression of BMP2, EIF2AK3, EIF2A, ATF4 caused by liquid nitrogen. Alendronate could be a promising strategy of curing ONFH via targeting BMP2/EIF2AK3/EIF2A/ATF4 pathway.

Long-term Anticoagulation Prevents Progression of Stages I and II Primary Osteonecrosis of the Hip in Patients With Familial Thrombophilia

The authors prospectively assessed long-term anticoagulation outcomes (≥3 years) for 9 patients meeting 4 inclusion criteria: pretreatment Ficat stage I or II primary hip osteonecrosis (ON), factor V Leiden or prothrombin G20210A heterozygosity, no contraindication to anticoagulation, and 90-day participation in an initial enoxaparin 60 mg/d protocol. The primary endpoint was prevention of hip collapse (Ficat stage III or IV). The secondary endpoint was pain relief. After 90 days of enoxaparin 60 mg/d, anticoagulation was continued for 8 patients: 4 receiving warfarin (international normalized ratio targeted to 2 to 2.5; 11.5, 13, 14.5, and 21 years), 1 receiving enoxaparin 120 mg/d (11.5 years), and 3 receiving novel oral anticoagulants (5, 6, and 8 years). Radiographs were obtained before treatment; at 3 to 4, 6 to 8, and 12 to 14 months; and then annually. By selection, 8 patients had factor V Leiden heterozygosity and 1 had prothrombin G202010A heterozygosity. Of their 13 hips (Ficat I or II at entry), 12 remained Ficat I or II after 12±5 years (range, 5.5-21 years) of continuous anticoagulation and follow-up; 1 hip radiographically normalized. None of the 13 hips progressed to collapse (Ficat III or IV). Six patients became symptom free after the first 3 months of receiving enoxaparin, 1 after 6 months of anticoagulation, and 1 after 10 months of anticoagulation; all 8 patients remained symptom free with anticoagulation. Anticoagulation for primary hip ON before hip collapse in patients with familial thrombophilia may change the natural history of ON because most untreated patients with ON have joint collapse and total joint replacement within 2 years of original symptoms. [Orthopedics. 2020;43(4):e208-e214.].

Rapid Onset of Femoral Head Osteonecrosis After a Single Intra-articular Hip Joint Injection of Corticosteroid

We outline a case in which osteonecrosis of the femoral head developed in temporal association with a single intra-articular injection of corticosteroid (triamcinolone acetonide) in a 72-yr-old woman, resulting in a total hip arthroplasty. We conclude that the risk of developing osteonecrosis after a single intra-articular injection of corticosteroid needs to be considered in the informed consent process.

How to evaluate the clinical outcome of joint-preserving treatment for osteonecrosis of the femoral head: development of a core outcome set

Background

This study aimed to develop a core outcome set (COS) for clinical trials of joint-preserving treatment for osteonecrosis of the femoral head (ONFH), that is, to define a minimal set of outcomes that should be reported in such trials.

Methods

A mixed research method was adopted in this study. First, clinical trials of hip preservation therapy were systematically researched and analyzed. Second, a three-round Delphi survey involving both doctors and patients was carried out to obtain the core outcome indicators. Round 1 was a modified Delphi questionnaire for doctors and patients to determine which outcomes are important to these stakeholders, round 2 determined what clinical evaluation core outcomes should be included for the joint-preserving treatment of ONFH, and round 3 determined how core outcomes should be measured. Finally, a consensus meeting was held to discuss and vote on the established COS.

Results

The results of the systematic review showed that 42 outcome indicators were classified according to common signs and symptoms, quality of life, long-term outcomes, radiological evaluation, blood biochemistry, and indexes of safety. The three rounds of Delphi surveys completed the selection of indicators for the COS and the determination of the corresponding measurements.

A total of 73 orthopedic doctors and 103 patients participated in round 1, and the top 10 indicators selected were basically the same. In round 2, 32 experts identified the following indicators: pain, range of motion (ROM) of hip flexion, walking distance, and stable rating of X-ray images. In round 3, 35 experts defined the measurement of each indicator. Finally, the consensus meeting identified the four indicators aforementioned that constituted the COS.

The scores for pain, ROM of hip flexion, and walking distance are from 0 to 10; 0 represents the best scores, while 10 represents the most serious impairment. The stable rating of X-ray images is determined by the morphology of the femoral head and the change in the density of the necrotic area.

Conclusions

We established a COS for hip-preserving treatment of ONFH that includes four indicators: pain, ROM of hip flexion, walking distance, and stable rating of X-ray images.

[Atraumatic and aseptic osteonecrosis of large joints]

Subchondral osteonecrosis of large weight-bearing joints (hip and knee joints) represents a severe and joint-threatening disease. Apart from idiopathic forms, glucocorticoid medication and alcohol abuse have been identified as major causative factors for atraumatic osteonecrosis. In addition to direct cytotoxic factors, a critically reduced perfusion of the subchondral osseous space will eventually lead to bone marrow ischemia and osseous necrosis. Magnetic resonance imaging (MRI) is capable of visualizing a reactive border-like zone in this early, already irreversible and often asymptomatic stage I according to the Association of Research Circulation Osseous (ARCO) staging system. Later in the course, osteonecrosis progresses to form serpiginous sclerotic lines, enclosing the necrotic bone area (stage II ARCO). Repair mechanisms of osteonecrosis are mostly unsuccessful and depending on the size of the osteonecrosis result in biomechanical failure and ultimately subchondral insufficiency fractures (crescent sign), thus marking the transition to stage III ARCO (joint surface collapse).

A comparison of subtraction MRI with the standard contrast-enhanced imaging in Perthes' disease

PURPOSE

Perthes' disease (PD) results from loss of blood supply to the hip and can progress to femoral head deformity. MRI in the early course of the disease can provide data on the initial extent of infarct. Vascularity of the femoral head is assessed by gadolinium-enhanced MRI (contrast MRI), which may be improved by the digital subtraction technique (subtraction MRI). We hypothesized that gadolinium-enhanced MRI without subtraction was comparable with subtraction MRI in depicting the femoral head perfusion.

METHODS

In all, 34 patients (34 hips) with unilateral PD had gadolinium-enhanced MRI as part of a prospectively randomized study. Nine patients had three MRIs, 15 had two and ten had a single MRI. Measurement of perfusion of the femoral head (MRI perfusion index) was obtained using digital image analysis on all the MRIs, including both before and after subtraction. A paired sample t-test was performed to compare the measurements.

RESULTS

The mean age of the patients was 8.9 years (sd 1.6). At the time of diagnosis, the subtraction MRI did not elicit a statistically significant difference in MRI perfusion index measurements when compared with the contrast MRI (p = 0.19). The same findings were found when including all patients at various stages of the disease (p = 0.30). Qualitatively, although some subtraction MRI images showed superior delineation of epiphysis, there are no significant differences throughout the whole series.

CONCLUSION

Although the current literature supports the increasing role of the subtraction MRI for PD management, our study proposed that the contrast MRI without subtraction technique appears adequate in assessing femoral head perfusion.

LEVEL OF EVIDENCE

Level I - Diagnostic study.

Monitoring of Osteonecrosis in Systemic Lupus Erythematosus: A Systematic Review and Metaanalysis

Objective.

Nontraumatic osteonecrosis (ON) is a well-recognized complication causing disability and affecting quality of life in patients with systemic lupus erythematosus (SLE). The aim of this study was to identify the risk factors for ON, and to identify the minimal investigation(s) needed to optimally monitor the risk of ON in patients with SLE.

Methods.

A systematic review was conducted using MEDLINE and EMBASE. These databases were searched up to January 2016 using the Medical Subject Heading (MeSH) terms “Osteonecrosis,” “Systemic lupus erythematosus,” and synonymous text words. Randomized controlled trials, case control, cohort, and cross-sectional studies were included. Risk factors for ON in patients with SLE were compiled. The quality of each study was assessed using the Newcastle-Ottawa scale for nonrandomized studies. The quality of evidence of each risk factor was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation method.

Results.

Of the 545 references yielded, 50 met inclusion criteria. Corticosteroid (CS) use may be strongly associated with ON in patients with SLE. Other clinical variables were moderately associated, including hypertension, serositis, renal disease, vasculitis, arthritis, and central nervous system disease. However, the evidence was low to very low in quality.

Conclusion.

Based on the best evidence available, CS use may be strongly associated with ON in patients with SLE. Results of this review were considered in the development of recommendations for the diagnosis and monitoring of patients with SLE in Canada and will guide clinicians in their assessment of these patients.

Drilling Combined with Adipose-derived Stem Cells and Bone Morphogenetic Protein-2 to Treat Femoral Head Epiphyseal Necrosis in Juvenile Rabbits

This study was designed to evaluate the effects of drilling through the growth plate and using adipose-derived stem cells (ADSCs) and bone morphogenetic protein-2 (BMP-2) to treat femoral head epiphyseal ischemic necrosis, which can be done in juvenile rabbits. Passagefour bromodeoxyuridine (BrdU)-labeled ADSCs were cultured, assayed with MTT to determine their viability and stained with alizarin red dye to determine their osteogenic ability. Two-month-old, healthy male rabbits (1.2 to 1.4 kg, n=45) underwent ischemic induction and were randomly divided into five groups (group A: animal model control; group B: drilling; group C: drilling & ADSCs; group D: drilling & BMP-2; and group E: drilling & ADSCs & BMP-2). Magnetic resonance imaging (MRI), X-ray imaging, hematoxylin and eosin staining and BrdU immunofluorescence detection were applied 4, 6 and 10 weeks after treatment. Approximately 90% of the ADSCs were labeled with BrdU and showed good viability and osteogenic ability. Similar results were observed in the rabbits in groups C and E at weeks 6 and 10. The animals of groups C and E demonstrated normal hip structure and improved femoral epiphyseal quotients and trabecular areas compared with those of the groups A and B (P<0.01). Group D demonstrated improved femoral epiphyseal quotients and trabecular areas compared with those of groups A and B (P<0.05). In summary, drilling through the growth plate combined with ADSC and BMP-2 treatments induced new bone formation and protected the femoral head epiphysis from collapsing in a juvenile rabbit model of femoral head epiphyseal ischemic necrosis.

Avascular Necrosis of Talus Diagnosed on Tc-99m MDP Bone Scan

Avascular necrosis (AVN) of bone is defined as the cellular death of bone components due to the interruption of the blood supply; the bone structures then collapse, resulting in pain and loss of joint function. Magnetic resonance imaging (MRI) is the gold standard to diagnose AVN. We present an unusual case of AVN of talus in a patient of thalassemia major that was diagnosed on the Tc-99m MDP bone scan with equivocal findings on MRI. Key Message: The diagnosis of AVN is primarily done using radiological investigations. However, the bone scan plays a role in the diagnosis in atypical presentations and should be considered when MRI is equivocal.

Case report: primary osteonecrosis associated with thrombophilia-hypofibrinolysis and worsened by testosterone therapy

Background

Familial and acquired thrombophilia are often etiologic for idiopathic hip and jaw osteonecrosis (ON), and testosterone therapy (TT) can interact with thrombophilia, worsening ON.

Case presentation

Case 1: A 62-year-old Caucasian male (previous deep venous thrombosis), on warfarin 1 year for atrial fibrillation (AF), had non-specific right hip-abdominal pain for 2 years. CT scan revealed bilateral femoral head ON without collapse. Coagulation studies revealed Factor V Leiden (FVL) heterozygosity, 4G/4G plasminogen activator inhibitor (PAI) homozygosity, high anti-cardiolipin (ACLA) IgM antibodies, and endothelial nitric oxide (NO) synthase (eNOS) T786C homozygosity (reduced conversion of L-arginine to NO, required for bone health). Apixaban 5 mg twice daily was substituted for warfarin; and L-arginine 9 g/day was started to increase NO. On Apixaban for 8 months, he became asymptomatic. Case 2: A 32-year-old hypogonadal Caucasian male had 10 years of unexplained tooth loss, progressing to primary jaw ON with cavitation 8 months after starting TT gel 50 mg/day. Coagulation studies revealed FVL heterozygosity, PAI 4G/4G homozygosity, and the lupus anticoagulant. TT was discontinued. Jaw pain was sharply reduced within 2 months.

Conclusions

Idiopathic ON, often caused by thrombophilia-hypofibrinolysis, is worsened by TT, and its progression may be slowed or stopped by discontinuation of TT and, thereafter, anticoagulation. Recognition of thrombophilia-hypofibrinolysis before joint collapse facilitates anticoagulation which may stop ON, preserving joints.