Percutaneous microwave ablation, perfusion, and reconstruction combined with a synthetic bone substitute in symptomatic bone cysts: a minimum of 26 months follow-up.

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 cm3 before surgery treatment to 13.9 cm3 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.

Outcomes and complications of surgical treatment modalities for simple bone cysts of the humerus in children and adolescents.

PURPOSE: The aim of this study was to evaluate and compare different surgical treatment modalities for simple bone cysts (SBC) of the humerus regarding their effectiveness and recurrence rate. METHODS: In this retrospective study, patients who received surgical treatment for previously untreated primary SBCs of the humerus were analyzed. Demographic data, cyst-specific as well as treatment-specific parameters, complications, treatment failures, and recurrence rates were collected and correlated with different treatment modalities. Observed procedures were categorized as open procedure (n=20) or osteosynthesis alone (n=3). For the open procedure group, four subgroups could be defined. RESULTS: Twenty-three patients were included. The mean age at diagnosis was 11.6 ± 2.5 years, and the mean postoperative follow-up was 3.9 ± 2.6 years (range 1.0-10.3). After surgical intervention, a total of five (21.7%) patients showed at least one recurrence. Fracture occurred in three (13.0%) cases. The incidence of treatment failure was significantly higher in the curettage, allograft, adjuvants group, with five (83.3%) of six cases showing recurrence, than in the other subgroups (≤ 25.0%) including the osteosynthesis alone group (p=.024). For the open procedure group, the failure-free survival rates were 80.0% after two years and 50.4% after five years. For the three cases treated by osteosynthesis alone, no failures were observed. CONCLUSION: Open procedures showed similar failure rates except for the subgroup using curettage, allograft, and adjuvants which showed significantly higher treatment failure. Promising results were observed in the group which received solely osteosynthesis without cyst excision or filling, as no treatment failure was observed here.

Arthroscopically guided lag screw fixation of subchondral bone cysts in the medial femoral condyle in Thoroughbred racehorses: description of technique and comparative results.

OBJECTIVE: To describe an arthroscopically guided technique for lag screw placement across subchondral bone cyst (SBC) in the medial femoral condyle (MFC) and to compare postoperative racing performance with corticosteroid injection and cyst debridement. STUDY DESIGN: Retrospective cohort study. ANIMALS: One hundred twenty-three horses with 134 MFC SBCs undergoing treatment at a single referral hospital in the UK between January, 2009, and December, 2020. METHODS: Sex, age, limb affected, radiographic cyst dimensions, preoperative and postoperative lameness, surgical technique (lag screw placement, cyst debridement, intralesional corticosteroid injection), and, where applicable, screw positioning were recorded retrospectively. A ratio was calculated using measurements from preoperative and postoperative radiographs. Outcome was assessed by resolution or improvement in lameness, reduction in cyst size, and starting one race after treatment. Outcome data was compared between treatment groups. RESULTS: Twenty-six of 45 (57.8%) horses that underwent transcondylar screw placement raced postoperatively, at a median of 403 days between surgery and first postoperative race. There was no difference between treatment groups with regard to racing or preoperative and postoperative lameness. Cysts treated with transcondylar screw placement had a greater reduction in cyst size and a reduced period of convalescence in comparison with those that underwent debridement; the results were similar to those treated by intralesional corticosteroid injection. CONCLUSION: Postoperative racing rates were similar for all techniques. Convalescence was reduced for lag screw placement and corticosteroid injection compared to debridement. CLINICAL SIGNIFICANCE: The arthroscopically guided technique results in radiographically consistent screw placement and cyst engagement and offers a viable alternative to other treatments.

Equine subchondral lucencies: Knowledge from the medial femoral condyle.

Equine subchondral lucencies (SCL) have been described since the first availability of suitable radiographic equipment. The initial clinical sign can be lameness, but SCLs are often first found on surveys of juvenile horses and are primarily a radiographic concern for public auctions. When lameness is present, it varies from subtle to obvious and can be intermittent. Some SCLs heal spontaneously, and some remain blemishes, but when the SCL and lameness are persistent, further damage to the joint and limitations to an athletic career are likely. SCLs were initially described in the distal limb followed by the stifle, and the medial femoral condyle (MFC) is now considered the most common location. The aim of this review is to highlight the initial pathology and discuss the clinical and experimental information available on equine SCLs. SCL treatment has evolved from rest alone and has progressed to debridement, grafting, intralesional injection, and most recently, transcondylar screw and absorbable implant placement. Comparison of success rates between techniques is difficult due to variations in follow-up and outcome measures, and no single technique is best for all SCLs. Treatment appears to increase success by 15%-20% over rest alone, but the method chosen depends on many factors. This review emphasizes the need for further work to fully understand SCL formation and all aspects of trabecular bone healing to optimize surgical therapy and improve treatment success.

Results of Allografts and Synthetic Grafts in Humeral Simple Bone Cysts.

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.

[Research progress of subchondral bone cyst after cartilage repair].

Subchondral bone cysts after cartilage repair are abnormal cavities that develop near the site of repaired cartilage defects and may communicate with the joint cavity.Research indicates that they may be associated with factors such as elevated external hydraulic pressure, bone bruising due to abnormal stress, internal inflammation, and inadequate blood supply.These cysts are closely linked to bone marrow edema.It has been observed that cysts following cartilage repair frequently occur after various procedures, including bone marrow stimulation, autologous or allogeneic osteochondral transplantation, and autologous chondrocyte transplantation.They represent a significant pathological change post-cartilage repair, influencing the process, quality, and outcome of the repair.Consequently, they have become an important parameter for evaluating the effectiveness of cartilage repair.This article provides a review of studies on the occurrence, development mechanisms, and pathological structures of subchondral bone cysts after cartilage repair using different techniques.It explores the clinical implications and potential of utilizing these cysts to assess the success of cartilage repair, enhancing understanding in this field.Such insights are expected to lay a foundation for the prevention and treatment of subchondral bone cysts following various cartilage repair procedures.

Long-Term Outcomes of Decompression and Grafting in Acute Pathological Proximal Femur Fractures in Children with Unicameral Bone Cysts: A Retrospective Study Utilizing a 120° Fixed-Angle Low-Contact Locking Pediatric Hip Plate.

BACKGROUND Unicameral bone cysts (UBCs) are benign tumor-like lesions that are the most common cause of pathological proximal femur fracture in children. This study aimed to present the outcomes of acute, unstable, pathological proximal femur fractures secondary to UBCs in children. MATERIAL AND METHODS We retrospectively reviewed data on 12 patients with a mean age of 9.3 years (7-12 years) who were initially treated with decompression and grafting, followed by stabilization using a 120° fixed-angle low-contact locking pediatric plate (LCLPP). The Musculoskeletal Tumor Society (MSTS) scores, Capanna classification of cyst repair, time to union, collodiaphyseal angle (CDA), and limb length discrepancy (LLD) were evaluated. RESULTS The mean follow-up was 33.1 months (range, 13-96 months). The mean union time was 9.5 weeks (8-14 weeks). The mean time for reparation of the cyst was 6.9 months (range 3-9 months). Four patients had Dormans type IB, while the remaining had type IIB fractures. According to the Capanna classification, repairs in 10 cases were grade I and in 2 cases grade II. At the last follow-up, the mean 120.8° of preoperative CDA was corrected to 140.9° (P<0.001) and there was no difference compared to the healthy side (P=0.214). The mean postoperative MSTS score was 97.1% (29.1 points). Two patients experienced LLD at the affected extremities, while the other 10 patients healed without any complications. CONCLUSIONS Fixation of acute unstable fractures secondary to UBCs with a 120° fixed-angle LCLPP is a reliable and successful option after decompression and grafting of the lesion.

Editorial Commentary: Large, Deep, and Cystic Osteochondral Lesions of the Talus May Be Better Treated With Bone Grafting Techniques or Autologous Osteochondral Transplantation Rather Than Bone Marrow Stimulation.

Osteochondral lesions of the talus are a challenging problem to treat. Debridement with bone marrow stimulation has represented the mainstay of treatment for the injuries, with good to excellent results reported. However, some patients do not do well with simple debridement and bone marrow stimulation, which yields a surface of fibrocartilage rather than articular cartilage. Recent studies have focused on prognostic indicators of successful treatment with bone marrow stimulation techniques, including lesion size, ankle stability, lesion location, containment, and the presence of a cyst, among others. The presence of a large bone cyst may be an indication for a more aggressive approach. Cystic lesions may be better suited for bone grafting techniques or articular cartilage replacement procedures (e.g., autologous osteochondral transplantation). Of importance, lesions larger than 90-100 mm sq and deeper than 7.5 mm may be similarly treated.

Concomitant Subchondral Bone Cysts Negatively Affect Clinical Outcomes Following Arthroscopic Bone Marrow Stimulation for Osteochondral Lesions of the Talus.

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 mm2 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 mm2) 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 mm2 vs 56.08 ± 22.92 mm2; 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 mm3 vs 134.58 ± 89.68 mm3; 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 mm2, depth of 7.56 mm, and volume of 428.13 mm3 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 mm2, depth of 7.56 mm, and volume of 428.13 mm3 were the potential cutoff values associated with poor outcomes after BMS. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Subchondral bone cysts remodel after correction of varus deformity in ankle arthritis.

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 mm3. 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.

Are Fibular Allograft Struts Useful for Unicameral Bone Cysts of the Proximal Humerus in Skeletally Mature Patients?

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.

Treatments and Sequelae of Pediatric Pathologic Proximal Femur Fractures Due to Benign Bone Cyst.

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.

Surgical treatment of benign lesions and pathologic fractures of the proximal femur in children.

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.

Treatment of bone cysts by percutaneous injection of demineralized bone matrix mixed with bone marrow.

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.

Traumatic bone cyst in the mandibular ramus - A diagnostic dilemma.

Traumatic bone cysts (TBCs) are uncommon, nonneoplastic lesions occurring more commonly in the metaphysis of the long bones and contribute to only 1% of the cysts occurring in the jaws. Seen more commonly in the mandible between the canine and third molar, their occurrence in the ramus-condyle region is very rare. The radiographic appearance of this lesion is like odontogenic keratocyst (OKC) or ameloblastoma and, therefore, extremely challenging to diagnose. Misdiagnosis often results in aggressive treatment for an otherwise innocuous entity. The purpose of this article is to encourage the surgeon to consider the possibility of a TBC when encountering asymptomatic large lytic lesions in the ramus of the mandible especially in younger individuals to avert an extensive radical surgery.

Comparison of three treatment methods for simple bone cyst in children.

BACKGROUND: The unicameral bone cyst (UBC) is a kind of benign tumor whose clinical treatments and efficacy are controversial. The purpose of this study was to evaluate the efficacy of the elastic stable intramedullary nail (ESIN), the injection of autologous bone marrow (ABM), and the combination of ESIN and ABM in the treatment of bone cyst in children. METHODS: Eighty-three cases with simple bone cyst were analyzed retrospectively. Twenty-eight cases were treated with ABM. Twenty-eight cases were treated with ESIN. Twenty-seven cases were treated with ABM and ESIN. All cases were diagnosed through X-ray, CT, or MRI scans. For the suspicious ones, the pathological biopsy was performed for an accurate diagnosis. X-ray examinations were carried out for the postoperative follow-up. Capanna criteria for bone cyst was used for postoperative evaluation of three methods. RESULTS: All cases accomplished the follow-up. The effective rate of the ABM + ESIN group was significantly higher than that of the ABM group (P < 0.05), and the cure rates of the ESIN group and the ABM + ESIN group were higher than that of the ABM group (P < 0.05, respectively). The cure time in the ESIN group was lower than that of the other two groups (P < 0.05, respectively). The times for admission were 2.0 ± 0.0 in the ESIN group, 5.7 ± 1.9 in the ABM group, and 4.7 ± 2.4 in the ABM + ESIN group (P < 0.05 when compared with each other). CONCLUSIONS: The method of ABM combined with ESIN for children's bone cyst has the highest effective rate and curative rate. For the individual method, ESIN has a higher effective rate and curative rate than that of ABM. Meanwhile, it has the fewest time of hospitalization.

Synthetic Bone Graft Substitute for Treatment of Unicameral Bone Cysts.

BACKGROUND: Treatments for unicameral bone cysts (UBCs) have high documented failure rates (27% to 63%) because of recurrence or persistence of the cyst, similar to nonoperative management. Recent evidence suggests that filling of the defect with a synthetic bone graft substitute (SBGS) supports the weakened cortex and promotes new bone growth. A calcium sulfate, brushite, calcium phosphate, composite graft material (PRODENSE, Wright Medical, Memphis, TN) has been evaluated as a substitute for autogenous or allogenous graft in animal and human studies. The purpose of this study was to compare the rates of revision surgery in patients treated for UBCs with an SBGS compared with historical treatments with allograft or autologous bone marrow aspirate. METHODS: The authors reviewed 27 of 33 patients (age, 6 months to 21 years) an average of 121 months (range, 32 to 228) after filling of a UBC with an injection of SBGS (n=18) versus allograft or autologous bone marrow aspirate (n=9) between June 2008 and December 2017. Six patients with no follow-up were excluded. Groups did not differ in age at surgery, sex (19/27 male), history of pathologic fracture (22/27), or previous treatments (11/27). The primary outcome was the rate of revision surgery. Secondary outcomes included revision surgery-free survival as evaluated by the log-rank test, rate of postoperative fracture, persistent cysts, continued pain, and/or growth disturbance at the final follow-up. RESULTS: Seven of 9 patients treated with allograft or autograft underwent revision surgery for postoperative pathologic fracture (n=2) or resorption of the graft (n=5) compared with 2 of 18 patients injected with the SBGS, both treated for graft resorption. The use of SBGS was associated with a decreased need for revision surgery over all time periods (hazard ratio, 0.14; 95% confidence interval, 0.03-0.05). There was no significant difference between postoperative fracture (2/18 vs. 2/9), persistent cyst (7/18 vs. 5/9), pain (0/18 vs. 2/9), or growth disturbance (1/18 vs. 3/9). CONCLUSIONS: Treatment of UBCs with SBGS may decrease reoperation rates. Initial radiographic appearance after SBGS treatment shows solid structural support, followed by new bone formation. This appearance may lead to a less aggressive approach in considering revision surgery. LEVEL OF EVIDENCE: Level III-retrospective comparative study investigating the results of treatment.

Subchondral bone cysts regress after correction of malalignment in knee osteoarthritis: comply with Wolff's law.

PURPOSE: The purpose of this study is to discuss the mechanical function of subchondral bone cysts and its relationship with Wolff's law. METHODS: One hundred forty symptomatic knees (120 patients) with osteoarthritis were subjected to MRI before high tibial osteotomy (HTO). Subchondral bone cysts (SBCs) were detected on 72 knees of these 140 knees. SBCs, bone marrow lesion (BML), and hip-knee-ankle (HKA) axis were measured by using validated methods. After HTO, the evolution of cysts was evaluated on MRI performed with a five year follow-up on the 72 knees with pre-operative cysts. RESULTS: At baseline, 70 (97%) of these 72 knees had a BML surrounding the SBCs; the maximum cyst volume was 874 mm3 and the average cyst volume 9. 6 ± 4.1 mm3. In the subregions where cysts were present, adjacent cartilage was still present without full thickness defects. The mean pre-operative hip-knee-ankle angle was 7.3 ± 3 degrees (0° to 14°) of varus and differed significantly (p = 0.01) between the 68 knees without cysts (average 3 ± 2 degrees) and the 72 knees with cysts (average 9.2 ± 4 degrees). Five years after HTO, the number of cysts had decreased, the maximum cyst volume was 532 mm3, and the average cyst volume was 6.3 ± 2.8 mm3. CONCLUSION: Regression of subchondral bone cysts may be related to restoration of an appropriate load at the subchondral bone. With applying poroelasticity to bone mechaincs, this finding may suggest that SBCs and BMLs may be a physiological adaptation to mechanic overload. More basic research is needed to prove this matter.

Efficacy of Lesion Specific Portals in Endoscopic Treatment of Calcaneal Bone Cyst: A Case Report and Literature Review.

Background: Calcaneal bone cysts rarely occur and most of them are known to be benign. Among them, simple bone cysts (SBCs) third most commonly occur in the calcaneus and of the many surgical treatment options, endoscopic curettage is recently gaining popularity among surgeons due to its advantages of minimal invasiveness and optimal visualization. As for portal placement for endoscopy, two lateral portals are considered a standard technique, but no rationale has been established for SBCs with abnormal geometry. This case report suggests an SBC with secondary aneurysmal change located outside the Ward's triangle, as well as an appropriate endoscopic approach. Case Presentation: An 18-year-old male high school student presented with a main complaint of pain at the hind foot level for the past one year, without significant improvement from conservative treatment. An endoscopic curettage through the lesion specific two posterior portals and bone graft using allogeneic cancellous bone were performed. SBC with a secondary aneurysmal bone cyst was diagnosed on pathology. At a one-year follow-up, the patient was painless and had returned to his regular activities. Physical and radiographic examinations revealed that the lesion was completely healed without any evidence of recurrence. Conclusion: For calcaneal bone cysts located at the posterior aspect of the calcaneus, eccentrically medial and abnormally long anterior-posteriorly, we suggest an endoscopic procedure using lesion specific portals such as two posterior portals.

Pediatric physeal slide-traction plate fixation for pathological distal femoral fracture caused by unicameral bone cyst in adolescents.

BACKGROUND: Most patients suffering from distal femoral unicameral bone cysts (UBCs) are adolescents that require an early return to normal activities, including school attendance and sports exercises. However, the optimal choice of implants for such patients remains controversial. This study evaluated the application of pediatric physeal slide-traction plate (PPSP) in the treatment of pathological distal femoral fracture caused by UBCs. METHODS: Between Jan 2014 and Jan 2016, 11 (male = 6, female = 5) patients were reviewed retrospectively. Age, sex, operative time, limb-length discrepancy (LLD), and valgus angulation were all recorded for every patient. RESULTS: The average age of 11 patients was 12.2 ± 1.1 years. The operating time was 94.8 ± 7.8 min. The postoperative hospital stay was 5 to 7 days. The epiphyseal morphology in the operative leg was nearly normal. The plate was removed in an average of 19.5 ± 3.1 months. The knee range of motion (ROM) was normal in 9 patients, whereas 2 female patients reported a loss of less than 10 degrees of ROM as compared to the contralateral knee joint. Breakage of plates or refracture did not occur in our cases. All patients had a follow-up of at least 24 months. At the latest follow-up visit, all patients walked without a limp. None of the patients manifested obvious LLD and valgus deformity. CONCLUSION: PPSP combined with curettage and bone grafting allows early mobilization and produces satisfactory outcomes for pathological fracture of distal femur secondary to UBCs in adolescents.