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Magnetic resonance imaging (MRI) is increasingly used in the classification and evaluation of osteoarthritis (OA). Many studies have focused on knee OA, investigating the association between MRI-detected knee structural abnormalities and knee pain. Hip OA differs from knee OA in many aspects, but little is known about the role of hip structural abnormalities in hip pain. This study aimed to systematically evaluate the association of hip abnormalities on MRI, such as cartilage defects, bone marrow lesions (BMLs), osteophytes, paralabral cysts, effusion-synovitis, and subchondral cysts, with hip pain. We searched electronic databases from inception to February 2024, to identify publications that reported data on the association between MRI features in the hip joint and hip pain. The quality of the included studies was scored using the Newcastle-Ottawa Scale (NOS). The levels of evidence were evaluated according to the Cochrane Back Review Group Method Guidelines and classified into five levels: strong, moderate, limited, conflicting, and no evidence. A total of nine studies were included, comprising five cohort studies, three cross-sectional studies, and one case-control study. Moderate level of evidence suggested a positive association of the presence and change of BMLs with the severity and progress of hip pain, and evidence for the associations between other MRI features and hip pain were limited or even conflicting. Only a few studies with small to modest sample sizes evaluated the association between hip structural changes on MRI and hip pain. BMLs may contribute to the severity and progression of hip pain. Further studies are warranted to uncover the role of hip MRI abnormalities in hip pain. The protocol for the systematic review was registered with PROSPERO ( https://www.crd.york.ac.uk/PROSPERO/ , CRD42023401233)., (© 2024. The Author(s).)

Background: A variety of treatment options for unicameral bone cysts (UBC) exist. The controversy of open management of UBC is discussed. The aim of this study was to analyze a single institution's experience in the open surgical treatment of UBC., Patients and Methods: By retrospective analysis of the Vienna Bone and Soft Tissue Tumor Registry, 119 patients with open surgery and histologically verified UBC with a mean follow up of 4.8 years (range 1-30 years) were included. Lesion treatment failure was defined as surgically addressed UBC undergoing revision surgery due to persistence or recurrence., Results: Local revision-free survival for lesion treatment failure was 93% after 1 year, 80% after 2 years, 60% after 5 years and 57% after 10 years. Of the patients 34 (29%) had at least 1 revision surgery due to lesion treatment failure. We found that patients with lesion treatment failure were younger (p = 0.03), had UBC with less minimal distance to the growth plate (p = 0.02) and more septation chambers in radiologic imaging (p = 0.02). Patients with open revision surgery were less likely to require a second revision due to lesion treatment failure than patients with percutaneous revision surgery (p = 0.03)., Conclusion: Open surgery for UBC can only be recommended as reserve treatment in younger children with actively growing lesions. Open UBC surgery carries a relatively high risk of almost 30% of lesion treatment failure and therefore the indications should be limited to extensive osteolysis with high risk of pathological fractures, lesions with displaced pathological fractures, and lesions with an ambiguous radiological presentation that require tissue collection., (© 2023. The Author(s).)

Purpose: To evaluate the safety, effectiveness, and patient satisfaction of doxycycline sclerotherapy for aneurysmal bone cysts (ABCs) and unicameral bone cysts (UBCs)., Materials and Methods: This was an institutional review board (IRB)-approved single-center retrospective review of all ABCs and UBCs of the appendicular skeleton and pelvis completing doxycycline sclerotherapy and having at least 2 years of follow-up from 2007 to 2021. Radiographic outcomes in a patient cohort were assessed with a modified Neer score. Patient-reported outcome (PRO) surveys were completed by a subgroup of the cohort assessing pain after treatment (Likert scale), functional outcomes (Patient-Reported Outcomes Measurement Information System), and overall patient satisfaction (adapted from the Musculoskeletal Tumor Society)., Results: Seventy-seven lesions met the inclusion criteria, with 55 (71%) receiving bone void filler in addition to doxycycline. Of the 77 lesions, 76 (99%) were successfully treated. Twelve lesions (16%) recurred but resolved with additional doxycycline treatment. One lesion failed sclerotherapy, requiring surgical excision. Of the 383 total treatments performed, 17 resulted in Society of Interventional Radiology (SIR)-classified adverse events (9 with Grade 1, 7 with Grade 2, and 1 with Grade 3). Twenty-five (32%) of the 77 cases completed PRO surveys, with 20 (80%) having little to no pain and 15 (60%) having no functional impairment after completing treatment. The PRO surveys documented high levels of satisfaction, with all patients agreeing that they would undergo doxycycline sclerotherapy again if given the option., Conclusions: Doxycycline sclerotherapy (with or without bone void filler) is a safe, effective, and well-tolerated stand-alone treatment for ABCs and UBCs., (Copyright © 2024 SIR. Published by Elsevier Inc. All rights reserved.)

Post-traumatic cortical cystic lesions are rare radiolucent lesions that appear as a complication of low-severity fractures in children. Their relevance lies in the fact that few cases of these lesions have been described to date, so they are little known among clinicians caring for children. Three case reports of well-circumscribed cortical lytic lesions detected at 2-4 months during the follow-up of non-displaced distal radius fractures in children aged 9, 7, and 2 years are presented. The consistent clinical history and typical radiological features allowed the accurate diagnosis of post-traumatic cortical cystic lesion, without the need for advanced imaging tests or biopsy. At 12-, 8- and 11-month follow-ups, respectively, the lesions either disappeared or decreased in size. This benign and self-limited lesion should be correctly recognized to avoid confusion with other diagnoses, advanced imaging tests or biopsies, and unnecessary parental concerns., (© 2024. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Objective: To assess the feasibility of a novel transcoronal approach for the treatment of axial type 3 cysts of the palmar/plantar aspect of the distal phalanx (P3)., Study Design: Ex vivo, experimental study., Sample Population: Ten cadaveric specimens, four forelimbs and six hindlimbs., Methods: All cadaveric specimens underwent radiographically guided drilling, followed by cortical screw placement. The cartilage was macroscopically assessed after disarticulation of the distal interphalangeal joint. The entry point and trajectory were evaluated with computed tomography. Results were categorized as: axial, near-axial and abaxial. The minimal distance from the outer margin of the drill hole and the proximal border of the subchondral bone plate was measured using frontal computed tomographic slices., Results: Eight of the 10 screws were in an axial to near-axial position and nine followed the desired axial to near-axial trajectory. One screw was inserted axially but continued in an abaxial trajectory. Iatrogenic damage to the joint cartilage, flexor cortex and solar canal of P3 was not observed. All cortical screws were placed close to the proximal subchondral bone-plate of P3., Conclusion: The desired axial/near-axial drilling and screw placement, under radiographic guidance, was achieved in nine out of 10 specimens., Clinical Significance: This novel technique seems promising for the treatment of inaccessible P3 cysts. Additional studies are required to investigate its feasibility in clinical cases, and the long-term outcome following transcystic screw placement of type 3 P3 cysts., (© 2024 American College of Veterinary Surgeons.)

Post-traumatic lipid inclusion cysts are a rare entity seen following fractures in paediatric patients. They often occur in the distal radius, developing 1-3 months following an extra-articular fracture. Although benign and self-limiting in nature, adequate awareness and accurate radiographic interpretation is key in avoiding further unnecessary non-invasive or invasive investigations. We report on a case of post-traumatic lipid inclusion cyst and review the literature., (© 2024 Royal Australian and New Zealand College of Radiologists.)

Aims: The purpose of this study was to assess the success rate and functional outcomes of bone grafting for periprosthetic bone cysts following total ankle arthroplasty (TAA). Additionally, we evaluated the rate of graft incorporation and identified associated predisposing factors using CT scan., Methods: We reviewed a total of 37 ankles (34 patients) that had undergone bone grafting for periprosthetic bone cysts. A CT scan was performed one year after bone grafting to check the status of graft incorporation. For accurate analysis of cyst volumes and their postoperative changes, 3D-reconstructed CT scan processed with 3D software was used. For functional outcomes, variables such as the Ankle Osteoarthritis Scale score and the visual analogue scale for pain were measured., Results: Out of 37 ankles, graft incorporation was successful in 30 cases. Among the remaining seven cases, four (10.8%) exhibited cyst re-progression, so secondary bone grafting was needed. After secondary bone grafting, no further progression has been noted, resulting in an overall 91.9% success rate (34 of 37) at a mean follow-up period of 47.5 months (24 to 120). The remaining three cases (8.1%) showed implant loosening, so tibiotalocalcaneal arthrodesis was performed. Functional outcomes were also improved after bone grafting in all variables at the latest follow-up (p < 0.05). The mean incorporation rate of the grafts according to the location of the cysts was 84.8% (55.2% to 96.1%) at the medial malleolus, 65.1% (27.6% to 97.1%) at the tibia, and 81.2% (42.8% to 98.7%) at the talus. Smoking was identified as a significant predisposing factor adversely affecting graft incorporation (p = 0.001)., Conclusion: Bone grafting for periprosthetic bone cysts following primary TAA is a reliable procedure with a satisfactory success rate and functional outcomes. Regular follow-up, including CT scan, is important for the detection of cyst re-progression to prevent implant loosening after bone grafting., Competing Interests: All authors report a grant from the National Research Foundation of Korea (NRF) funded by the Korea government Ministry of Science and ICT (MSIT) (Grant No. NRF-2017R1A2B4007245), related to this study., (© 2024 The British Editorial Society of Bone & Joint Surgery.)

Aims: The aim of this study is to evaluate the surgical treatment with the best healing rate for patients with proximal femoral unicameral bone cysts (UBCs) after initial surgery, and to determine which procedure has the lowest adverse event burden during follow-up., Methods: This multicentre retrospective study was conducted in 20 tertiary paediatric hospitals in France, Belgium, and Switzerland, and included patients aged < 16 years admitted for UBC treatment in the proximal femur from January 1995 to December 2017. UBCs were divided into seven groups based on the index treatment, which included elastic stable intramedullary nail (ESIN) insertion with or without percutaneous injection or grafting, percutaneous injection alone, curettage and grafting alone, and insertion of other orthopaedic hardware with or without curettage., Results: A total of 201 patients were included in the study. The mean age at diagnosis was 8.7 years (SD 3.9); 77% (n = 156) were male. The mean follow-up was 9.4 years (SD 3.9). ESIN insertion without complementary procedure had a 67% UBC healing rate after the first operation (vs 30% with percutaneous injection alone (p = 0.027), 43% with curettage and grafting (p = 0.064), and 21% with insertion of other hardware combined with curettage (p < 0.001) or 36% alone (p = 0.014)). ESIN insertion with percutaneous injection presented a 79% healing rate, higher than percutaneous injection alone (p = 0.017), curettage and grafting (p = 0.028), and insertion of other hardware combined with curettage (p < 0.001) or alone (p = 0.014). Patients who underwent ESIN insertion with curettage had a 53% healing rate, higher than insertion of other hardware combined with curettage (p = 0.009). The overall rate of postoperative complications was 25% and did not differ between groups (p = 0.228). A total of 32 limb length discrepancies were identified., Conclusion: ESIN insertion, either alone or combined with percutaneous injection or curettage and grafting, may offer higher healing rates than other operative procedures. Limb length discrepancy remains a major concern, and might be partly explained by the cyst's location and the consequence of surgery. Therefore, providing information about this risk is crucial., Competing Interests: None declared., (© 2024 The British Editorial Society of Bone & Joint Surgery.)

Background: Whether arthroscopic microfracture is effective in treating cystic osteochondral lesions of the talus (OLTs) remains controversial. In this study, outcome parameters in patients with small and shallow subchondral cysts are compared to patients without cysts with the hypothesis that equivalent outcomes may be found after primary microfracture treatment., Methods: From 2018 to 2021, all 50 OLTs treated with arthroscopic microfracture in the authors' hospital were retrospectively reviewed for eligibility. Single unilateral symptomatic lesions were included and divided into the cyst and noncyst groups, whereas kissing lesions and arthritic lesions were excluded. Numeric rating scale (NRS) scores, American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scores, Tegner activity level scores, Foot and Ankle Ability Measure (FAAM) scores, and magnetic resonance (MR) imaging results were used to describe outcomes., Results: A total of 35 patients were included, 16 in the cyst group and 19 in the noncyst group. The patient characteristics were similar between the 2 groups ( P  > .05). In the cyst group the average cysts depth was 5.0 ± 1.3 mm. After a mean follow-up duration of 36.2 ± 10.2 months, no significant differences were found between the 2 groups in NRS, AOFAS, FAAM, or Tegner score improvement ( P  > .05). Three patients (19%) in the cyst group had no NRS score improvement., Conclusion: OLTs with small and shallow subchondral cysts can be treated with arthroscopic microfracture and achieve similar outcomes as noncystic lesions. A few cystic lesions may not respond to microfracture treatment., Level of Evidence: Level III, retrospective comparative study., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Objective: To investigate the diagnosis and treatment of intraosseous ganglion cyst in the ankle region., Methods: A retrospective analysis was performed on the diagnosis and treatment of 18 patients with intraosseous ganglion in the ankle region from January 2005 to March 2016. There were 11 males and 7 females, with an average age of 40.4 years (22-74 years). Thirteen of these had mild intermittent localized pain in the ankle and five were asymptomatic and fortuitously found on images. According to the location of the intraosseous ganglion cyst, nine were located in the distal end of tibia, seven were in the distal end of the fibula, and two were in the talus. After curettage of intraosseous ganglion, 15 cases were filled with autogenous iliac bone and 3 cases with artificial bone., Results: Fifteen cases were diagnosed with radiographs and CT scans, two cases with MR images, and one case was confirmed by postoperative pathology. The cyst contents were jelly-like material with sclerotic bone margins. The mean size of the intraosseous ganglion cyst was 1.5 cm × 1.5 cm × 1 cm. Hematoxylin and eosin (H&E) staining of the tissue showed fibrous tissue, collagenous fiber, mucoid, and a few fibroblasts. Eighteen cases were followed up for 11 months to 10 years, with an average of 5.4 years. No recurrence was found. Sixteen patients were asymptomatic after surgery. Two cases of ankle pain occurred at 1 year and 6 months postoperatively, respectively. According to the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale, the mean AOFAS ankle-hindfoot score improved from 78.2 ± 13.7 points preoperatively to 97.3 ± 4.5 points at the final follow-up., Conclusion: For the intraosseous ganglion cyst in the ankle region, whether there are clinical symptoms or not, the cyst should be curettaged and the cavity should be filled with bone graft. The operation result is satisfactory., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Objective: To investigate the radiologic, pathologic, and molecular features of simple bone cysts (SBC), and their differential diagnoses. Methods: Fourteen cases of SBC were collected at the Department of Pathology, the First Affiliated Hospital of Nanjing Medical University from 2017 to 2022, and fluorescence in situ hybridization (FISH) was performed for retrospective analysis. Results: There were 14 patients, including 7 females and 7 males, with age range of 7 to 45 (median 29) years. The most common complaint was pain, including 4 cases with pathological fracture and 5 with history of previous trauma. The tumor size ranged from 3.4 to 13.5 (median 5.6) cm. The lesion involved the femur ( n= 4), humerus ( n= 5) and iliac bone ( n= 5). Radiologic diagnoses included SBC, aneurysmal bone cyst, and giant cell tumor of the bone or its combination with aneurysmal bone cyst-like region and fibrous dysplasia. Histologically, the cyst walls of the lesions were composed of fibrous tissue, fibrin-like collagen deposits, bone-like matrix and occasional woven bone. The lesional cells were spindled to ovoid, with scattered osteoclast-like giant cells, foamy histiocytes, hemosiderin deposits and cholesterol clefts. In 6 cases there were nodular fasciitis-like areas. Immunohistochemically, the spindled to ovoid cells were positive for SMA, EMA and SATB2 in varying degrees. FISH detection was performed in all 14 cases and EWSR1/FUS rearrangement were found in 9 cases. One case of FUS::NFATC2 fusion was detected by next-generation sequencing. Nine cases of SBC with the rearrangement were more cellular, and there were more mitotic figures in the recurrent FUS::NFATC2 fusion tumor. Clinical follow-up was obtained in all 14 cases with the time ranging from 5 to 105 (mean 46) months. Amongst them, the tumor with FUS::NFATC2 rearrangement had local recurrence twice after the first local excision, but had no more recurrence or metastasis 34 months after the subsequent segmental resection. The other 13 cases had no recurrence. Conclusions: EWSR1 or FUS rearrangement is most commonly identified in SBC, suggesting that SBC might be a neoplastic disease. In cases where the radiologic appearance and histomorphology are difficult to differentiate from aneurysmal bone cyst, FISH detection can aid in the definitive diagnosis.

Introduction: Proximal femur simple bone cysts (SBCs) are rare in children, but with a risk of pathological fractures and the associated poor outcomes. This study aimed to evaluate the functional and radiographic outcomes of children with proximal femur SBCs., Patients and Methods: 38 children with proximal femur SBCs treated surgically at our department, West China hospital, were enrolled in the study. Patients were divided into two groups according to whether pathological fractures presented before treatment. The non-fracture group received treatment of open curettage, cavity electrocauterization, bone grafting, and fixation (proximal femoral plate, intramedullary nail or Kirschner wire). The pathological fracture group received the same procedures of curettage, electrocauterization, grafting, and fixation. Autogenous iliac bone grafting was done in all cases, and the artificial bone was used as a supplementary based on the size of the cavity. Postoperatively, all patients underwent hip spica or similar orthosis immobilization for six weeks and received the same rehabilitation program after the removal of hip spica. Patients were evaluated by two independent observers, including the functional results based on the Ratliff's criteria, avascular necrosis, healing rate based on the Neer scoring system, coxa vara, and premature physeal arrest. We described the good outcome in Ratliff's criteria as "Satisfactory results", and fair and poor outcomes as "Unsatisfactory results." Grade 1 and grade 2 Neer results were termed as failures in treatment, and grades 3 and 4 were considered successes and healing., Results: 38 patients with 38 hips (18 on the left side and 20 on the right side) were evaluated, including 9 females and 29 males, with a mean age of 9.0±2.6 years old (range, 5 to 14 years). There was no significant difference between these two groups in the baseline data of gender, age, side, grafting, staging, and fixation methods. The rate of unsatisfactory functional results in the pathological fractures group was 56.3% (9/16), significantly higher than that in patients without fracture (22.7%, 5/22. p= 0.047). There was also a significant difference in avascular necrosis of the femoral head between the pathological fractures group (7/16) and the group without fracture (2/22, p=0.021). Thirty cases presented with healing, including 13 in the fractures group and 17 in the non-fracture group (p=1.000), and eight cases were graded as failures (2 cases of grade 1 and 6 cases of grade 2). There were also no significant differences between these two groups in premature physeal arrest (2 in fracture group and 1 in non-fracture group, P=0.562), and Coxa vara (3 in the fracture group and 0 in non-fracture group, P=0.066)., Conclusions: Pathological fracture significantly increases the risk of unsatisfactory functional results and avascular necrosis of the femoral head in patients with femoral neck SBCs. Prophylactic treatment and fixation of SBCs in weight bearing proximal femur region is better to manage without complications than managing with pathological fractures., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier Ltd.)

Purpose: To evaluate the Sclerograft™ procedure, which is an image-guided, minimally invasive approach of chemical sclerotherapy followed by bone grafting of unicameral bone cysts (UBC)., Materials and Methods: A retrospective evaluation from August 2018 through August 2023 was performed at a single institution on patients that underwent the Sclerograft™ procedure for UBCs. Radiographic healing was evaluated utilizing the Modified Neer Classification. Two different regenerative grafts, CaSO 4 -CaPO 4 and HA-CaSO 4 were utilized. A total of 50 patients were evaluated with 41 patients grafted with CaSO 4 -CaPO 4 and 9 patients grafted with HA-CaSO 4 ., Results: The average age of the patient was 12.1 years with an average radiographic follow-up of 14.5 months. Average cyst size was 5.5 cm in the largest dimension and average cyst volume was 20.2 cc. 42 out of 50 (84%) showed healed cysts (Modified Neer Class 1) on the most recent radiograph or MRI. Recurrences occurred on average at 7.2 months. Activity restrictions were lifted at 3-4.5 months post-procedure. Cyst stratification by size did not show a difference in recurrence rates (p = 0.707). There was no significant difference in recurrence rate between lesions abutting the physis compared to those that were not abutting the physis (p = 0.643). There were no major complications., Conclusions: The Sclerograft™ procedure is an image-guided approach to treating unicameral bone cysts, utilizing chemical sclerosis and regenerative bone grafting. The radiographic healing of cysts compares favorably to open curettage and grafting as determined utilizing previously published trials., (© 2024. Springer Science+Business Media, LLC, part of Springer Nature and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE).)

Objective: To investigate whether subchondral bone cysts (SBCs) were present in dogs with radiographic elbow osteoarthritis (OA) and to investigate their relationship with radiographic OA severity., Study Design: Retrospective cross-sectional study., Sample Population: Thirty-eight Labrador retrievers (total of 76 elbows)., Methods: Elbow computed tomography (CT) images of 18 young (≤2 years old) and 20 old (>2 years old) Labrador retrievers, which presented for elbow-associated lameness, were reviewed. Radiographic elbow OA was graded into four groups based on the largest osteophyte size on CT. The presence, number, and maximum diameter of SBCs were determined., Results: Subchondral bone cysts were only identified in elbows with osteophytic new bone formation. The number and size of SBCs were associated with radiographic OA severity (p < .001 and p = .041 respectively). Specifically, the rate at which SBCs were present increased for both moderate and severe OA in comparison with the mild OA (moderate OA RR = 2.46, 95% CI 2.08-2.92, p < .001; severe OA RR = 5.60, 95% CI 4.79-6.55, p < .001). For dogs with severe OA, there was an increased likelihood that their SBCs were larger than SBCs from dogs with mild OA (OR = 1.056, 95% CI 1.012-1.101, p = .012). No SBCs were observed in elbows without radiographic evidence of OA., Conclusion: Subchondral bone cysts were identified as a feature of radiographic elbow osteoarthritis in Labrador retrievers, and their number and size were indicative of the presence and severity of radiographic elbow OA., Clinical Significance: Subchondral bone cysts are a potential imaging biomarker for quantitative assessment for canine OA., (© 2023 The Authors. Veterinary Surgery published by Wiley Periodicals LLC on behalf of American College of Veterinary Surgeons.)

Background: Individuals with high systemic bone mineral density (BMD) may have an increased risk of incident knee osteoarthritis (OA). Besides that, radiographic osteophytes are strongly associated with BMD. Because of these reasons, the aim of the study was to investigate the possible association between radiological subchondral bone cyst (SBC) grade and systemic BMD and vitamin D status in the postmenopausal female patients with knee OA in a crosss-sectional study., Methods: This study included of 48 osteoporosis treatment-free postmenopausal patients diagnosed with symptomatic medial compartment knee OA. BMD analysis was performed using dual-energy X-ray absorptiometry (DXA) and serum vitamin D levels were measured after recording patients' findings. Each knee was scanned using computed tomography (CT), and categorical SBC scores were graded for the medial and lateral tibiofemoral (TF) and patellofemoral (PF) compartments and further calculated as compartmental total, total TF and grand total of both TF compartments. SBC scores were analysed with correlation analysis., Results: The patient population was characterized by radiographic joint space narrowing, obesity and low vitamin D status. Median medial total and grand total TF SBC scores were significantly different between the patient groups according to the Kellgren-Lawrence (KL) radiographic grading (p = 0.006 and p = 0.007, respectively). There were no correlations between femoral BMD values and SBC scores. However, positive correlations were detected significantly between L 1 - 4 DXA values and TF SBC scores, but not with PF SBC scores (p = 0.005 for the correlation between L 1 - 4 BMD and medial compartments total TF SBC score, p = 0.021 for the correlation between L 1 - 4 BMD and grand total TF SBC score). No significant correlations were found with Vitamin D levels., Conclusions: Development of TF OA high-grade SBCs may be linked to systemic bone mass as represented by trabecular bone-rich lumbar vertebrae. The relationship might point to the importance of bone stiffness as an acting factor in knee OA possibly with mechanical energy transfer to the joint., (© 2024. The Author(s).)

» Unicameral bone cysts (UBCs) can increase the risk of pathologic fractures of both long and short bones. Although multiple treatments exist, data are conflicting regarding optimal management., » We sought to analyze treatment strategies for UBCs and their rates of successful treatment., » Success rates were analyzed according to treatment modality, with emphasis on filling techniques and/or decompression associated with curettage, and injection compounds., » Curettage with bone substitute and cyst decompression was identified as a highly successful technique for UBC treatment., » Decompressing the cyst wall after injection, regardless of the specific compound used, had a greater potential to enhance healing rates., » The management decision should be individually guided within the patient's context., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSREV/B56)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Purpose of the Study: Simple bone cysts (SBCs) are the most common benign bone lesions in childhood. There are many different methods in the treatment of SBCs. There is no consensus on which method to use in the treatment. In this study, we compared the results of allogeneic bone graft or synthetic bone graft in addition to fl exible intramedullary nail (FIN) for SBC located in the humerus., Material and Methods: This retrospective study comparing the data of 19 (group 1: 8 curettage, allograft and FIN; group 2: 11 curettage, synthetic graft and FIN) patients with a mean age of 11.4 (6 to 26; seven female, twelve male) who were surgically treated in our hospital for humeral SBC between April 2014 and January 2020. Patient data included age, sex, anatomical side, stage of the cyst, pathological fracture, previous treatments and complications., Results: The mean follow-up period was 33.7 months (12 to 61). The average last follow-up Musculoskeletal Tumor Society functional scores for groups 1 and 2 were 27.8 (20 to 30) and 28.6 (21 to 30) (P > 0.05). Complete or signifi cant partial radiographic healing rates were achieved in group 1 (75%) compared with group 2 (81.9%). The reoperation rates for groups 1 and 2 were 62.5% (5/8; three for nails removed, two for recurrence) and 36.3% (4/11; two for nails removed, two for recurrence). One patient in group 2 had a 15° varus deformity due to recurrence. No other complications were observed., Conclusions: The combination of curettage-grafonage FIN is a common treatment method in recent years, as it provides early cyst healing and limb mobilization in SBCs located in the upper extremity. For defects after curettage of the bone cysts, allogeneic or synthetic grafts (granule b-tricalcium phospate) which have similar results in terms of healing can be used as an alternative to each other., Key Words: allografts, bone cysts, bone nails, synthetic grafts, humerus.

Purpose: The objective was to describe the technique and clinical outcome of microwave thermal ablation (MWA) and perfusion combined with synthetic bone substitutes in treating unicameral bone cysts (UBCs) in adolescents., Materials and Methods: A total of 14 consecutive patients were enrolled by percutaneous MWA and saline irrigation combined with synthetic bone substitutes. Clinical follow-up included the assessment of pain, swelling, and functional mobility. Radiological parameters included tumor volume, physis-cyst distance, cortical thickness of the thinnest cortical bone, and the Modified Neer classification system., Results: The mean follow-up was 28.9 months (26-52 months). All UBCs were primary, and all patients underwent the MWA, saline perfusion, and reconstruction combined with a synthetic bone substitute session, except for one patient (7.1%) who required a second session. All patients had good clinical results at the final follow-up. Satisfactory cyst healing was achieved in 13 cases according to radiological parameters. Tumor volume decreased from a mean of 49.7 cm 3 before surgery treatment to 13.9 cm 3 at the final follow-up ( p  < 0.01). The physis-cyst distance increased from a mean of 3.17-4.83 cm at the final follow-up ( p  < 0.01). Cortical thickness improved from a mean of 1.1 mm to 2.0 mm at the final follow-up ( p  < 0.01). According to the proposed radiological criteria, our results were considered successful (Grading I and II) in 13 patients (92.9%) at the final follow-up., Conclusion: Percutaneous microwave ablation combined with a bone graft substitute is a minimally invasive, effective, safe, and cost-effective approach to treating primary bone cysts in the limbs of adolescents.

Objective: Osteochondral lesions of the talus (OLT) is a common and clinically challenging disease. The optimal management is still under debate. The purpose of this prospective study was to investigate the feasibility and clinical outcomes of autologous costal osteochondral transplantation (ACOT) for the treatment of cystic OLT., Methods: From November 2021 to April 2023, five patients underwent autologous costal osteochondral transplantation (ACOT) for cystic OLT. The demographic data was described, including age, gender, lesion size and location. We prospectively evaluated their functional and imaging outcomes of the five patients for 12 months postoperatively, including numeric rating score (NRS) for pain when walking, Tegner score, American Orthopedic Foot & Ankle Society (AOFAS) score and Foot and Ankle Ability Measure (FAAM) score, and imaging results. A paired t-test was used for preoperative and postoperative comparison of the paired-design dataset., Results: The average age was 36.6 ± 11.1 years. The average diameter of chondral lesions was 14.95 ± 2.71 mm, the average diameter of subchondral cysts was 10.66 ± 1.84 mm, and their average depth was 10.40 ± 1.86 mm. At 12 months postoperatively, the clinical function indexes improved significantly, including NRS (from 5.2 ± 2.3 to 0), Tegner score (from 3.2 ± 0.4 to 5.8 ± 0.4), AOFAS score (from 72.8 ± 10.0 to 98.2 ± 4.0), and FAAM score (FAAM/ADL from 61.2 ± 24.7 to 99.3 ± 1.6; FAAM/Sports from 32.5 ± 13.73 to 96.3 ± 8.4). Their magnetic resonance observation of cartilage repair tissue (MOCART) scores reached 78.0 ± 7.6 points. ICRS scores of three patients were nearly normal (10 or 11 points). The biopsy of the surviving grafts showed plenty of hyaline cartilage matrix and scattered chondrocytes histologically. No major severe complications were reported during the 12 months follow-up., Conclusion: ACOT could significantly relieve the symptoms of patients with OLT and improve their clinical function at short-term follow-up. ACOT might be a feasible and useful method for repairing OLT with subchondral cysts., (© 2023 The Authors. Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.)

Purpose: To study the effects of concomitant subchondral bone cysts (SBCs) on prognosis after arthroscopic bone marrow stimulation (BMS) for osteochondral lesions of the talus (OLTs) less than 100 mm 2 and to further assess the correlation between cystic OLT area, depth, or volume and postoperative outcomes., Methods: We retrospectively analyzed consecutive patients with OLTs (<100 mm 2 ) who received BMS between April 2017 and May 2020 with a minimum follow-up of 24 months. Lesion area, depth, and volume were collected on preoperative magnetic resonance imaging. Visual analog scale (VAS), American Orthopedic Foot and Ankle Society, Karlsson-Peterson, Tegner, Foot and Ankle Ability Measure (FAAM)-Activities of Daily Life and Sports scores were assessed before surgery and at the latest follow-up. Additionally, a general linear model (GLM) and a Pearson correlation analysis (PCA) were performed to investigate the effects of concomitant cysts on postoperative results., Results: Eighty-two patients with a mean follow-up of 39.22 ± 12.53 months were divided into non-cyst (n = 45; 39.91 ± 13.03 months) and cyst (n = 37; 38.37 ± 12.02 months) groups. There was no significant difference in the OLT area between the non-cyst and cyst groups (46.98 ± 19.95 mm 2 vs 56.08 ± 22.92 mm 2 ; P = .093), but the cyst group showed significantly greater depth (6.06 ± 1.99 mm vs 3.96 ± 1.44 mm; P = .000) and volume (248.26 ± 156.81 mm 3 vs 134.58 ± 89.68 mm 3 ; P = .002). The non-cyst group showed significantly more improvement in VAS pain, Karlsson-Peterson, Tegner, and FAAM scores than the cyst group (P < .05). The GLM indicated that SBCs negatively affected VAS pain and Tegner scores (P < .05). For OLTs with cysts, the PCA showed that an area of 90.91 mm 2 , depth of 7.56 mm, and volume of 428.13 mm 3 were potential cutoff values associated with poor outcomes., Conclusions: The concomitant SBCs negatively affected the prognosis of OLTs after BMS. For OLTs with cysts, an area of 90.91 mm 2 , depth of 7.56 mm, and volume of 428.13 mm 3 were the potential cutoff values associated with poor outcomes after BMS., Level of Evidence: Level III, retrospective comparative study., (Copyright © 2023 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: This observational study aimed to elucidate the pathophysiology of subchondral cysts (SC) in the temporomandibular joint (TMJ) and examine the results of conservative therapy administered to patients with SCs in the TMJ., Methods: The study included 41 patients with SCs, extracted from 684 consecutive patients who underwent magnetic resonance imaging (MRI). The anatomical features of SCs and positional abnormalities of the articular disc were initially evaluated using MRI. A second MRI examination was performed for 28/41 patients at 40-107 months (mean, 66 months) after the first MRI. The joint space, anteroposterior width of the condylar head (WiC), articular eminence angle (AEA), and visual analog scale of jaw pain (VAS) were assessed alongside the MRI examinations., Results: Most SCs were present in the anterosuperior and central condyle. Disc displacement was observed in 100% of 42 TMJs with SCs. Of the 29 joints in 28 patients, SCs in 19 joints resolved with time, whereas SCs in 10 joints persisted. A significant increase in the WiC and a significant decrease in AEA and VAS scores were observed on the second MRI scan., Conclusions: SCs tended to form in the anterosuperior and central parts of the condyle, where mechanical loading was likely to be applied. SCs are strongly associated with articular disc displacement. Two-thirds of SCs resolved over time, accompanied by resorption and osteophytic deformation of the condyle. SC might not be an indicator for the start of surgical treatment, and nonsurgical treatment could improve the clinical symptoms of patients with SCs.

Spectral photon-counting computed tomography (SPCCT) is a new technique with the capability to provide mono-energetic (monoE) images with high signal to noise ratio. We demonstrate the feasibility of SPCCT to characterize at the same time cartilage and subchondral bone cysts (SBCs) without contrast agent in osteoarthritis (OA). To achieve this goal, 10 human knee specimens (6 normal and 4 with OA) were imaged with a clinical prototype SPCCT. The monoE images at 60 keV with isotropic voxels of 250 × 250 × 250 µm 3 were compared with monoE synchrotron radiation CT (SR micro-CT) images at 55 keV with isotropic voxels of 45 × 45 × 45 µm 3 used as benchmark for cartilage segmentation. In the two OA knees with SBCs, the volume and density of SBCs were evaluated in SPCCT images. In 25 compartments (lateral tibial (LT), medial tibial, (MT), lateral femoral (LF), medial femoral and patella), the mean bias between SPCCT and SR micro-CT analyses were 101 ± 272 mm 3 for cartilage volume and 0.33 mm ± 0.18 for mean cartilage thickness. Between normal and OA knees, mean cartilage thicknesses were found statistically different (0.005 < p < 0.04) for LT, MT and LF compartments. The 2 OA knees displayed different SBCs profiles in terms of volume, density, and distribution according to size and location. SPCCT with fast acquisitions is able to characterize cartilage morphology and SBCs. SPCCT can be used potentially as a new tool in clinical studies in OA., (© 2023. The Author(s).)

Background: Subchondral bone cysts (SBCs) of the talus are frequently observed in ankle osteoarthritis (OA). It is unclear whether the cysts need direct treatment after correction of the varus deformity in ankle OA. The purpose of this study is to investigate the incidence of SBCs and the change after supramalleolar osteotomy (SMOT)., Methods: Thirty-one patients treated by SMOT were retrospectively reviewed, and 11 ankles had cysts preoperatively. After SMOT without management of the cysts, the evolution of cysts was evaluated on weightbearing computerized tomography (WBCT). The American Orthopaedic Foot and Ankle Society (AOFAS) clinical ankle-hindfoot scale and a visual analog scale (VAS) were compared., Results: At baseline, the average cyst volume was 65.86 ± 60.53 mm 3 . The number and volume of cysts were reduced dramatically (P＜.05), and the cysts vanished in 6 ankles after the SMOT. The VAS and AOFAS scores improved significantly after SMOT (P＜.001), there was no significant difference between ankles with cysts and without cysts., Conclusions: The SMOT alone without direct treatment of the SBCs led to a decrease in the number and volume of SBCs in varus ankle OA., Level of Evidence: Level IV, case series., Competing Interests: Declaration of Competing Interest The author(s) declared no potential conflicts of interest with respect to the research, author- ship, and/or publication of this article., (Copyright © 2023 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Objectives: The objective of this work was to evaluate the incremental value of MR angiography over plain radiographs and MRI for the differentiation of aneurysmal bone cysts (ABCs) from unicameral bone cysts (UBCs)., Methods: Thirty-six juvenile patients with histologically secured primary ABCs or UBCs were included in this retrospective study. Two radiologists assessed all obtained images in a blinded fashion using a catalog of previously suggested imaging findings. A second readout with supplementary MR angiography images was performed after 8 weeks to prevent observer recall bias. Diagnostic accuracy parameters were calculated for individual imaging findings, and overall diagnostic accuracy and diagnostic confidence were assessed for all readouts. Receiver operating characteristic (ROC) curve comparison was used to determine the incremental value of MR angiography., Results: Of 16 imaging features, only abnormal vascularization in MR angiography provided sufficient diagnostic accuracy for the identification of ABCs. Other imaging features such as fluid-fluid levels and internal septations were insufficient for the differentiation of UBCs from ABCs. Availability of MR angiography images significantly increased diagnostic accuracy (94.4 vs 75.0% and 83.3 vs 69.4%, respectively, p < 0.05) and diagnostic confidence (4.5 vs 3.7, p < 0.05) of reading radiologists., Conclusion: The presence of arterial feeders in MR angiography can accurately discriminate primary ABCs from UBCs and increases the diagnostic accuracy and diagnostic confidence of reporting radiologists., Advances in Knowledge: Radiographic differentiation of cystic bone lesions such as ABCs and UBCs remains challenging. We demonstrate that MR angiography provides incremental value and suggest inclusion in standard examination protocols.

Background: Intraosseous ganglion cyst (IGC) of the talus is a rare entity. There is no consensus regarding the best surgical approach to the talus. In this study, we evaluated the outcomes of curettage and bone grafting of the talus IGC via medial malleolus osteotomy., Methods: Seventeen patients with talus IGC who were treated between 2002 and 2020 using curettage and bone grafting through a medial malleolus osteotomy were included. The outcome measures were ankle range of motion (ROM), pain, and function. The ankle pain was evaluated by the visual analog scale (VAS). The ankle function was evaluated by the Toronto extremity salvage score (TESS) and Musculoskeletal Tumor Society (MSTS) score., Results: The study population included 10 men and 7 women with a mean age of 34.9 ± 18.8 years and a mean follow-up of 5.4 ± 3 years. The mean size of the lesion was 2.6 ± 0.8 cm. Postoperatively, mean ankle dorsiflexion and plantar flexion were 19.4 ± 5.8 degrees and 36.7 ± 5.3 degrees, respectively. The mean VAS was 0.9 ± 1.1. The mean MSTS score and TESS were 96.2 ± 3.5 and 94.5 ± 4.1, respectively. Two patients developed ankle osteoarthritis after 3 years (1 stage I and 1 stage II). One of these patients (stage II) also had recurrence after 6 months (recurrence rate: 6.7%)., Conclusion: Talus IGC could be adequately managed with curettage and bone grafting through a medial malleolus osteotomy. Even so, mild pain and reduced ankle ROM remain in some patients., Level of Evidence: Level IV, retrospective cohort study.

Objective: To determine morphological characteristics of subchondral cystic lesions (SCLs) in the proximal phalanx (PP) of adult horses., Sample: Radiographs and/or CT scans of PP from 46 horses., Procedures: There were horses with a SCL in PP, which was diagnosed by radiography and/or computed tomography, included. Additional data (signalment, history, orthopedic examination) were collected retrospectively for each case., Results: Forty-six horses met the required inclusion criteria, with a total of 62 SCLs. Forty-three SCLs (70.5%) were located in the proximal PP (group A). Forty-four percent of these were associated with short, incomplete fractures, while 30 of the proximal PP SCLs (69.7%) were found mid sagittal. Proximal SCLs mostly showed a blurred, irregular shape (62.8%) and long, as well as wide, but shallow shapes in CT. Eighteen SCLs (29.5%) were found in the distal PP, near the proximal interphalangeal joint (group B). In contrast to the described proximal SCLs, the distal SCLs were of circular or oval shape, well delineated (77.8%), and distinctly larger. Horses of group A were significantly older (mean age, 11.47 years) than horses of group B (mean age, 6.72 years)., Clinical Relevance: The distribution and morphological attributes of proximal PP SCLs as well as their association to subchondral bone lesions and short, incomplete proximal fractures indicate more recently developed lesions due to chronic stress factors, such as repetitive trauma to the cartilage and subchondral bone. In contrast, morphology and distribution of distal SCLs showed high accordance with developmental bone cysts originating from a failure of endochondral ossification.

Background: Subchondral bone cysts are a common presentation in ankle haemarthropathy. The relationship with ankle joint health has however not previously been investigated. The aim of this study was to assess the influence of subchondral bone cysts of differing shapes, volumes and depths on joint health., Methods: Chronologically sequential Magnetic Resonance imaging scans of four hemophilic ankles with subchondral bone cysts present (N = 18) were used to build patient specific finite element models under two cystic conditions to assess their influence on cartilage contact pressures. Variables such as location, volume and depth were considered individually, to investigate whether certain cystic conditions may be more detrimental to cartilage health., Findings: Significant quantifiable contact redistribution was seen in the presence of subchondral bone cysts and this redistribution reflected the shape and size of the cysts, however, with the presence of cysts in both bones in 10 of the 18 cases a direct relationship to volume could not be correlated., Interpretation: This work demonstrated a redistribution of contact pressures in the presence of subchondral bone cysts. This alteration to loading history could be linked to cartilage degeneration due to the biological response to abnormal loading., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

Bone cysts whether aneurysmal or simple, are known for their tendency to recur. To replace the classical aggressive surgeries, minimally invasive techniques were developed giving differing results based on variable radiographic criteria. No unique percutaneous treatment has proven effective on both types of cysts. The purpose of this study was to evaluate with volumetric MRI calculations the benefit of percutaneous injection of demineralized bone matrix mixed with autogenous bone marrow on both types of cysts. Twenty-seven cysts; 6 aggressive aneurysmal bone cysts (ABCs) and 21 active simple bone cysts (SBCs) were treated with our percutaneous treatment in this case series. Regular MRIs were performed to calculate their volumetric evolution starting before treatment and with a minimal two-year follow-up. A cyst was considered healed when its final residual volume shrank to less than 50%. To allow statistical comparison between both types of cysts, 13 previously reported ABCs treated with the same protocol in our institution were joined to the 6 present ABCs. Four ABCs healed with a single injection while the 2 others recurred. Five SBCs healed with a single injection, 9 others after a second injection and 2 others after a third injection. Five SBCs were considered non-healed. The present healing rate in 67% of ABCs is consistent with the previous series as there was no significant difference (p=0.37). The better global healing rate for ABC (79%) was not statistically different from the SBC healing rate (76%) (p=0.83). The percutaneous injection of demineralized bone matrix mixed with bone marrow is an effective treatment for both types of cysts.

Objective: To determine if utilization of a decision tree algorithm could improve the healing rate of unicameral bone cysts (UBCs)., Methods: Creation of the decision tree algorithm was based on previous literature and assessment of our clinical practice. Demographic, treatment, and radiographic data were collected retrospectively. Radiographic healing was determined using the Neer classification. Healing rate, as well as clinical/radiographic characteristics, were compared based on adherence to the treatment algorithm., Results: Forty-seven subjects were included. Mean age at initial surgery was 10.0 ± 3.3 years in children following the algorithm and 9.1 ± 3.2 years in those deviating from the algorithm (p = 0.393). Follow-up was found to be similar among those following the algorithm (37.5 ± 15.8 months) and those deviating from the algorithm (45.2 ± 24.6 months), p = 0.38. Children who followed the algorithm healed at a rate of 75%, while children who deviated from the algorithm healed at a rate 67% (p = 0.552)., Conclusions: Although we reject our hypothesis that a decision tree algorithm for the management of UBCs in the pediatric population could improve the healing rate, we believe that we uncovered some utility in applying an algorithm to this pathology. Our algorithm was designed to minimize risk to the child and maximize healing with the least number of surgical events. Treating surgeons should consider this proposed pathway to determine the best treatment and to help families understand that these lesions rarely heal with a single-event surgery., Competing Interests: Dr. Edmonds has the following disclosures: American Academy of Orthopaedic Surgeons: Editorial or governing board; Arthrex, Inc: Paid presenter/speaker; Pediatric Orthopaedic Society of North America: Board or committee member, (Thieme. All rights reserved.)

Objective: Focal lesions within the subchondral bone, termed subchondral bone cysts (SBCs), are clinically accepted radiographic markers of advanced osteoarthritis (OA), but their etiology in the hip is not well understood., Design: This study used micro-computed tomography (μCT), and histological and immunocytological analysis to examine the prevalence, size, location, and morphological and cellular features of SBCs found within 34 femoral heads (14 male, 20 female; age range = 43-80 years) obtained from total hip arthroplasty procedures., Results: SBCs were common-present in 91% of the femoral heads examined-and frequently commuted with the surface of the femoral head, but otherwise showed no preferred anatomical location. Few associations were found between SBC features and patient characteristics such as BMI, age and sex. SBCs were also heterogenous in composition, ranging from fibrous (most common) to predominantly fatty (least common) and often containing vasculature, nerve fibers, cartilage islands, and bony spicules. Despite this heterogeneity, focal abnormalities in bone density and cartilage thickness were consistently observed. Bone adjacent to SBCs was denser than that in the primary compressive group, and cartilage thickness in regions overlying SBCs was lower than in non-overlying regions. In contrast to these local bony changes, μCT-based finite element analyses indicated that the stiffness of the primary compressive group was only mildly affected by SBCs., Conclusions: These findings indicate that SBCs in the femoral head involve extensive perturbations in cellular activity, culminating in myriad skeletal tissue types and spatially heterogenous changes in bone and cartilage morphology that are likely to affect OA progression., (Copyright © 2022 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Aneurysmal bone cyst (ABC) is a benign but locally aggressive lesion that predominantly affects children and young adults. ABC, which accounts for approximately 70% of the cases, is now recognized to be a true neoplasm, whereas ABC-like changes associated to other bone neoplasms (also referred in the literature as secondary ABC) accounts for the remaining 30%. The solid variant of ABC is also considered a true neoplasm but is rare. ABC can involve any bone in the body, and although it has a metaphyseal preference, it can involve any part of a bone and soft tissues. As with any bone tumor, the initial evaluation of ABCs should be done with radiographs followed by magnetic resonance imaging or less frequently computed tomography for further characterization. The imaging appearance of ABC is variable; however, a lytic and expansile lesion with fluid-fluid levels is the most common presentation. The main differential diagnosis of an ABC in the pediatric population is unicameral bone cyst (UBC) and telangiectatic osteosarcoma, therefore a biopsy is recommended before treatment. The therapeutic options of ABC range from curettage with or without adjuncts such as phenol, liquid nitrogen, argon laser and bone grafting or bone substitutes to more recently employed alternatives such as image-guided sclerotherapy with various sclerosing agents and monoclonal antibodies (e.g., Denosumab)., (© 2022. The Author(s).)

Background: The proximal femur is a common location for pathologic fractures in children, yet there is little published information regarding this injury. The purpose of this study was to investigate the outcomes of pediatric pathologic proximal femur fractures due to benign bone tumors., Methods: A retrospective review of patients treated for pathologic proximal femur fractures from 2004 to 2018 was conducted. Inclusion criteria were age below 18 years and pathologic proximal femur fracture secondary to a benign bone tumor. Patients were excluded if they had <1 year of follow-up. Medical charts and serial radiographs were reviewed for fracture classification, underlying pathology, treatment, complications, and time to fracture healing., Results: A total of 14 patients were included. Mean age was 6±3 (3 to 11) years, and mean follow-up was 44±21 (22 to 86) months. Index treatment was spica casting in 9/14 (68%) patients, while 5/14 (32%) were treated with internal fixation. Of the 9 patients initially treated with casting, 22% (2/9) required repeat spica casting at a mean of 0.6 months after index treatment, 67% (6/9) required internal fixation at a mean of 20.3 months after index treatment, and 11% (1/9) did not require revision treatment. Eighty-eight percent (8/9) of patients treated with casting required revision treatment compared with 40% (2/5) of those treated with internal fixation (P=0.05). Nonunion occurred after 1 refracture, malunion with coxa vara occurred in 2 fractures, and the remaining 11/14 (84%) fractures had a union at a mean of 4.9±3.0 months All cases of malunion occurred in patients initially treated nonoperatively. There were 19 distinct complications in 10/14 (71%) patients. The incidence of any revision surgery was 64% (9/14)., Conclusions: In this series, pediatric pathologic proximal femur fractures demonstrated prolonged time to union, high incidence of revision surgery (64%), and substantial complication rate (71%). In children with pathologic proximal femur fractures, treatment with internal fixation is recommended as this series showed a 78% failure rate of initial conservative management., Level of Evidence: Level IV., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Description of simple bone cyst (SBC) content has been controversial. This study aimed to assess and give a clearer picture of the SBC cavity contents. Between 2014 and 2016, 19 patients with SBC verified by histopathological examination were included in this study. SBC cavity content was investigated using clinical, radiographic, surgical, and laboratory findings. The difference in components among cavity fluid, blood, and serum was evaluated using a paired sample t-test for statistical analysis. All 19 SBC cases radiographically and surgically revealed a fluid-filled cavity. The patients' average age was 21.3 ± 13.2 years, with no sex predominance found. SBCs were found mostly in the anterior mandible (n = 12, 63.2%). All lesions were filled with clear straw-colored or blood-colored floods with low concentration. Although the fluid components were similar to those in the blood and serum in the laboratory analysis, the statistical analysis revealed that the fluid components were not significantly different only for eosinophil (p = 0.43) and basophil (p = 0.06) counts as blood components and sodium (p = 0.76), potassium (p = 0.08), and chloride (p = 0.13) concentration as serum components. The results show that SBC is a fluid-filled cavity, with the cavity fluid being more likely similar to serum rather than blood regarding internal components., (© 2022. The Author(s).)

Competing Interests: The author certifies that there are no funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article related to the author or any immediate family members. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

Background: Although most unicameral bone cysts (UBCs) are either successfully treated or have healed by the time of skeletal maturity, a small proportion of patients will have persistent UBCs beyond the age of skeletal maturity. More reliable methods are needed to treat persistent UBCs in the humerus because these cysts are associated with a high risk of fracture due to thinning of the humeral cortex. In this study, we evaluated whether inserting a fibular strut allograft into the humerus would be associated with healing of the cyst and union of associated pathologic fractures in skeletally mature patients with a UBC of the proximal humerus., Questions/purposes: (1) How effective is inserting a fibular strut allograft in the healing of proximal humerus UBCs in skeletally mature patients with bone cysts and associated fractures? (2) What are the functional results of this procedure? (3) What complications are associated with this procedure?, Methods: Between 2005 and 2018, we surgically treated 23 skeletally mature patients with persistent humeral UBCs and any of the following indications: a progressive cyst that was not responsive to aspiration and 2 to 3 steroid injections, a cyst with a pathologic fracture, and a cyst at high risk of fracture. Of those, patients with a cyst located in the proximal humerus and a defect length more than 6 cm (n = 18) were considered eligible to be treated with insertion of a fibular strut allograft through a hole created in the greater tuberosity. A further two patients were excluded because they were treated by other surgical methods. From the remaining 16 patients, two patients were lost to follow-up before 2 years and could not be analyzed in this study. Another two patients had incomplete datasets, leaving 12 for analyses in this retrospective study. Three patients presented with a pathologic fracture. Complete filling of the cysts with bone within 24 months was regarded as healing, and after 24 months it was classified as delayed healing. Cyst consolidation with small residual areas of osteolysis was considered healed with residual radiographic appearance. Fracture union was determined by the clear observation of at least three of four cortical views bridged by bone in the radiographic follow-up 3 months after the operation. Fractures in which the cortices were not bridged by bone after 3 months were regarded as a delayed union. The functional outcome of the patients was assessed by the Musculoskeletal Tumor Society (MSTS) scoring system, with a total score ranging from 0 to 30. A higher score was indicative of less pain and better function. MSTS scores were obtained through a chart review by an orthopaedist who was not involved in the care administered., Results: At a median (range) follow-up of 57 months (33 to 87), the cyst was completely healed in nine patients and healed with residual cyst in the remaining three. Union was observed within 3 months in all patients who presented with a pathologic fracture. The median MSTS score of the patients was 30 (28 to 30). No postoperative complications such as persistent pain or re-fracture were observed., Conclusion: The primary goal of treating a UBC of the proximal humerus is to prevent fracture of the affected bone; insertion of a fibular strut graft in this study met this goal. Therefore, we believe a fibular strut allograft insertion is worth consideration when treating proximal humeral UBCs in skeletally mature patients. Further studies will be needed to determine whether this approach has benefits compared with other treatment options., Level of Evidence: Level IV, therapeutic study., Competing Interests: Each author certifies that there are no funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article related to the author or any immediate family members. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2021 by the Association of Bone and Joint Surgeons.)

Objective: Recent studies have indicated that intraosseous lipomas originate from simple bone cysts of the calcaneus. This study evaluates computed tomography (CT) and magnetic resonance imaging (MRI) findings of calcaneal cysts and lipomas in pediatric and adult populations., Methods: Forty-six patients with bone lesions located in the anterior portion of the calcaneus beneath the talocalcaneal joint, who underwent CT and/or MRI, were enrolled in this study. The imaging characteristics were retrospectively reviewed and compared between the pediatric (aged 18 years or younger; n = 29) and adult (aged 19 years or older; n = 17) groups., Results: On CT images, water/soft tissue attenuation alone was more frequent in the pediatric group than in the adult group (84% vs 13%, respectively; P < 0.01), whereas the combined water/soft tissue and fat attenuation (11% vs 47%, respectively; P < 0.05) and fat attenuation alone (5% vs 40%, respectively; P < 0.05) were less frequent in the pediatric group than in the adult group. On MRI, cystic components alone were more frequent in the pediatric group than in the adult group (88% vs 13%, respectively; P < 0.01), whereas the combined cystic and fat components (8% vs 38%, respectively; P < 0.05) and fat components alone (4% vs 50%, respectively; P < 0.01) were less frequent in the pediatric group than in the adult group., Conclusions: Calcaneal cysts were more frequent in the pediatric group, whereas calcaneal lipomas were more frequent in the adult group. These results could be additional evidence that intraosseous lipomas originate from simple bone cysts of the calcaneus., Competing Interests: The authors declare no conflict of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Open curettage with bone graft has been the traditionally suggested surgical treatment for the symptomatic simple (or unicameral as they used to be called) calcaneal bone cyst. Less invasive endoscopically assisted treatment with curettage and bone grafting with allograft have recently provided less postoperative morbidity. The aim of the present study is to present our experience with this method in young soccer athletes. Between April 2014 and May 2016 three consecutive young soccer players with symptomatic calcaneal bone cysts underwent endoscopic curettage, and percutaneous injection of demineralized bone matrix allograft. The mean age was 17.3 (16, 17 and 19 years old), and the mean follow-up was 32.1 (range 24-47) months. Both radiographic and functional follow-up, using the AOFAS score, showed good to excellent results. All lesions were radiographically healed. Preoperative AOFAS score (max. 100 pts) was 78.6 ± 4.7, improving to 98.0 ± 4.1. The patients returned to their initial level of sports activities within 18.3 (range 17-19) weeks after surgery. Evidence suggests an earlier return to sports using bone substitutes. However, the present study showed that endoscopic curettage and percutaneous injection of bone allograft is also an excellent treatment option for young athletes with a symptomatic calcaneal bone cyst. LEVEL OF CLINICAL EVIDENCE: 4., (Copyright © 2021. Published by Elsevier Ltd.)

Purpose: Benign lesions of the proximal femur region, such as simple bone cysts, aneurysmal bone cysts, and fibrous dysplasia, are common in children. Benign lesions may cause pathologic fractures, limb length inequities, and growth disturbances. Differential diagnoses, e.g., malignant bone tumors and osteomyelitis, are sometimes difficult to rule out., Objective: We aimed to evaluate outcomes in children with benign lesions of the proximal femur treated with curettage, bone grafting, and plate fixation., Methods: In this retrospective study, we included 30 children (median age 10.5 years; range 1.1-17.8 years) suffering from bone cysts and tumor-like lesions of the proximal femur region treated between 2002 and 2018. We analyzed plain X-ray images and CT scans in all children and obtained MRI scans in a selected group of children (63.3%). We examined histopathologic biopsy results for all bone lesions before initiating treatment. Surgical management comprised tumor curettage with adjuvant high-speed drilling and allogenic bone grafting supplemented by bone graft substitutes before plate fixation. Median follow-up interval was 87 months (range 24-156 months). We evaluated the healing of lesions according to Capanna's classification and rated functional outcomes according to Merle d'Aubigné and Postel score., Results: Overall, 25 of 30 (83.3%) patients were admitted to hospital because of a pathologic fracture. We diagnosed simple bone cysts in 15 (50.0%) patients, aneurysmal bone cysts in 7 (23.5%) patients, and fibrous dysplasia in 8 (26.5%) patients. Bone consolidation was achieved in 22 of 30 (73.3%) patients after a mean of 5 months (range 3-7 months). The main complication was recurrence of the lesion in 4 of 30 (13.3%) patients. With respect to the Merle d'Aubigné and Postel scores, 17 of 30 (56.7%) patients obtained an excellent result (18 points), while 12 (40.0%) patients had a good result (15-17 points) and only 1 (3.3%) patient had a fair result (14 points)., Conclusion: Surgical treatment of bone cysts and tumor-like lesions of the proximal femur by local resection or destruction of the lesion, followed by filling the defect with bone graft material and internal stabilization represents a safe and effective treatment option in children., Level of Evidence: Therapeutic, retrospective comparative study-Level III., (© 2020. Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Unicameral bone cysts (UBCs) are benign lesions that primarily occur in childhood and can present with pain, pathologic fracture and growth disturbances. Existing treatment approaches for the management of UBCs are highly variable and recurrence is not uncommon. This study seeks to evaluate near-term outcomes of an image-guided, minimally invasive combination of chemical sclerotherapy and synthetic grafting as a novel outpatient management treatment option for UBCs., Materials and Methods: Retrospective evaluation from August 2018 to July 2020 of fourteen pediatric patients, ages 5-14 years, undergoing treatment for a UBC, at a single institution. All UBCs were treated in a single, minimally invasive, image-guided procedure using percutaneous needle access into the UBC followed by chemical sclerotherapy and injection of regenerative synthetic graft. Patients were followed clinically and with serial radiographs to evaluate for healing and complications, with an average follow-up of 13.7 months. Descriptive statistics were performed., Results: Twelve of 14 (85.7%) patients showed Modified Neer classification class 1 or 2 healed cysts at their most recent follow-up. There were two recurrences. All patients were pain-free and returned to normal physical activity on average within 2.0 months, and all patients with healed cysts remained asymptomatic at the most recent follow-up. There were no complications related to the procedures., Conclusions: Image-guided chemical sclerosis and bone grafting is a minimally invasive treatment option for unicameral bone cysts and compares favorably to other existing treatment options. The preliminary findings of this technique are promising as an alternative management option for UBCs., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE).)

The etiology of subchondral bone cysts (SBCs) is not fully understood. Mechanical trauma and fluid pressure are two mechanisms believed to cause their formation and growth. The equine stifle joint provides a natural animal model for studying SBCs. Computed tomography images of an extended yearling cadaveric stifle joint were segmented using ScanIP to isolate bones and relevant soft tissues. Three model geometries were created to simulate cyst sizes of approximately 0.03 cm 3 (C1), 0.5 cm 3 (C2), and 1 cm 3 (C3). A uniform pressure resulting in 3000 N force was applied at the proximal end of the femur. Two types of simulations, filled-cyst and empty-cysts with uniform pressure loads, were used to simulate fluid pressurization. Our models suggest that shear stresses are likely the cause of failure for the subchondral bone and not pressurized fluid from the joint. Bone stresses did not begin to increase until cyst pressures were greater than 3 MPa. For all cyst sizes, fluid pressure must rise above what is likely to occur in vivo in order to increase bone shear stress, shown to be most critical. Synovial fluid pressure acts upon a porous trabecular bone network, soft tissue, and marrow, so the continuum nature of our model likely overestimates the predicted effects of fluid pressures., (© 2021. Biomedical Engineering Society.)

Objective: To examine whether knee subchondral cysts, measured on magnetic resonance imaging (MRI), are associated with incident knee osteoarthritis (OA) outcomes., Methods: We used longitudinal data from the Multicenter Osteoarthritis Study, a community-based cohort of subjects with risk factors for knee OA. Participants without a history of knee surgery and/or inflammatory arthritis (i.e., rheumatoid arthritis and gout) were followed up for 84 months for the following incident outcomes: 1) radiographic knee OA (Kellgren/Lawrence grade ≥2), 2) symptomatic radiographic knee OA (radiographic knee OA and frequent knee pain), and 3) frequent knee pain (with or without radiographic knee OA). In a subset of participants, subchondral cysts were scored on baseline MRIs of 1 knee. Multiple logistic regression, with adjustment for participant characteristics and other baseline knee MRI findings, was used to assess whether subchondral cysts were predictive of incident outcomes., Results: Among the participants with knees eligible for analyses of outcomes over 84 months, incident radiographic knee OA occurred in 22.8% of knees with no baseline radiographic knee OA, symptomatic radiographic knee OA occurred in 17.0% of knees with no baseline symptomatic radiographic knee OA, and frequent knee pain (with or without radiographic knee OA) occurred in 28.8% of knees with no baseline radiographic knee OA and 43.7% of knees with baseline radiographic knee OA. With adjustment for age, sex, and body mass index, the presence of subchondral cysts was not associated with incident radiographic knee OA but was associated with increased odds of incident symptomatic radiographic knee OA (odds ratio 1.92 [95% confidence interval 1.16-3.19]) and increased odds of incident frequent knee pain in those who had radiographic knee OA at baseline (odds ratio 2.11 [95% confidence interval 0.87-5.12]). Stronger and significant associations were observed for outcomes based on consistent reports of frequent knee pain within ~1 month of the study visit., Conclusion: Subchondral cysts are likely to be a secondary phenomenon, rather than a primary trigger, of radiographic knee OA, and may predict symptoms in knees with existing disease., (© 2021 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

Competing Interests: Competing interests: None declared.

Objective: To screen the radiomic features of simple bone cysts of the jaws and explore the potential application of radiomics in pre-operative diagnosis of jaw simple bone cysts., Methods: The investigators designed and implemented a case-control study. 19 patients with simple bone cysts who were admitted to the Department of Maxillofacial Surgery, Sun Yat-sen University Affiliated Stomatology Hospital from 2013 to 2019 were included in this study. Their clinical data and cone-beam computed tomography (CBCT) images were examined. The control group consisted of patients with odontogenic keratocyst. CBCT imaging features were analyzed and compared between the patient and control groups., Results: Overall, 10,323 image features were extracted through feature analysis. A subset of 25 radiomic features obtained after feature selection were analyzed further. These 25 features were significantly different between the 2 groups ( p < 0.05). The absolute value of correlation coefficient was 0.487-0.775. Gray-level co-occurrence matrix (GLCM) contrast, neighborhood gray tone difference matrix (NGTDM) contrast, and GLCM variance were the features with the highest correlation coefficients., Conclusions: Pre-operative radiomics analysis showed the differences between simple bone cysts and odontogenic keratocysts, can help to diagnose simple bone cysts. Three specific texture features-GLCM contrast, NGTDM contrast, and GLCM variance-may be the characteristic imaging features of simple bone cysts of the jaw.

Introduction: Osteoarthritis in dysplastic hips should develop from the lateral side of the acetabulum and the femoral head just below. However, the existence of subchondral cysts located more on the medial side contradicts the weight-loading theory. The aim of this study was to confirm the presence of medial cysts at the femoral head and to investigate the relationship between medial cysts and injuries of the ligamentum teres in hip dysplasia., Methods: A retrospective analysis was conducted on 257 cases of hip dysplasia. All patients had x-rays and 3-dimensional computed tomographies (3D CT) preoperatively and 123 patients had magnetic resonance arthrographies. A comparison was performed between cases with and without medial cysts according to the severity of damage to the ligamentum teres, the presence of bony spurs around the fovea capitis, and the Tönnis grade., Results: Medial subchondral cysts around the fovea capitis were found in 100 cases. Mild osteoarthritis (Tönnis grade 0 or 1) was present in 89% of cases in the medial cyst group. A significant difference between the groups was observed in the incidence of bony spurs around the fovea capitis ( p  < 0.05) and injuries of the ligamentum teres ( p  < 0.05)., Conclusions: The formation of subchondral cysts at the medial femoral head in hip dysplasia may be related to damage in the ligamentum teres. Considering that subchondral cysts develop in early osteoarthritis, the progression of arthritis in hip dysplasia appears to correlate with damage to the ligamentum teres, as well as compressive pressure on the joint.