Hereditary Multiple Exostoses Research Articles

Forearm deformity in multiple hereditary exostosis. Radiologic predictors of radial head dislocation

IntroductionRadial head dislocation in patients with multiple hereditary exostosis (MHE) can lead to functional deficit. We investigated whether the location of the exostosis and certain radiological criteria predict risk of radial head dislocation/subluxation. HypothesisWe hypothesized that the radiological criteria differentiate between patients who need closer follow-up of the forearm and others for whom multiple radiographs are superfluous. Patients and methodsWe retrospectively reviewed the demographics of patients with MHE in our hospital, and radiographic measurements were made on forearm radiographs: radial length, ulnar length, ulnar variance, radial articular angle, and radial bowing. ResultsForty-nine forearms were analyzed in 30 patients. Mean age was 9.5 years at first evaluation and 11.8 years at last evaluation. Radial head dislocation or subluxation was found in 6 forearms (12%). Risk factors comprised isolated exostosis in the distal portion of the ulna or exostosis in the distal part of both the ulna and radius, radial or ulnar shortening>4.6cm, radial bowing>8.1%, radial articular angle>35°, and≥3 exostoses in the forearm. DiscussionIn patients with MHE with risk factors for radial head dislocation, close follow- up with regular radiography is indicated and early surgery should be performed before the radial head dislocates. Level of evidenceIV; retrospective study.

THE UNUSUAL PRESENTATION OF EXCESSIVE SPURS LIKE OSTEOCHONDROMAS IN AN ADOLESCENT WITH HEREDITARY MULTIPLE OSTEOCHONDROMAS

Hereditary Multiple Osteochondromatosis (HMO) is characterised by the presence of multiple osteochondromas, mainly affecting the long bones. Osteochondromas are bony projections that are either sessile or pendulated in form. Isolated osteochondromas in the form of spurs have been described as occurring in the knee and the foot. Reports of thorn-like osteochondromas affecting the ribs are extremely rare. We describe the unique case of an adolescent with multiple osteochondromas affecting the long bones. While in the lower limbs they were noted to be sessile and pendulated, they had the form of excessively elongated spurs in the radius. They created pain and limitation of his activities. The surgical removal of these spurs enabled us to restore activity in the patient's dominant (right) arm.

CLOSED WEDGE OSTEOTOMY FOR THE CORRECTION OF FOREARM DEFORMITIES IN HEREDITARY MULTIPLE OSTEOCHONDROMA A CASE REPORT.

Introduction-Hereditary multiple osteochondroma is rare form of skeletal dysplasia with autosomal inheritance .during childhood ,these cartilage capped bone tumors grow outward from long bone metaphysis ,leading to metaphyseal remodeling and asymmetric longitudinal bone growth. Forearm deformities affect 30% to 60%of patients with HMO. Patient typically complaining of functional disability cosmetic impairment ,and sometimes pain. The deformities may involve a relative shortening ulna bowing of radius, ulnar deviation of the hand and wrist and permanent subluxation or dislocation of radial head. A 15 years old male patient presented Presentation Of Case- with bowing of right forearm with occasionally pain and he also complaining of pain in right shoulder ,knee joint. on a scanogram of right forearm shows ulnar variance -10,radial articular angle 40 degree, radial bowing .07 ,and radial length (121)cm abnormal carpal slip 6 .The patient was managed with surgical intervention. radial osteotomy and resection of osteochondroma and xation with distal radius locking plate and immobilization with long arm cast. patient recover with correction of deformity. The study ndings conrm our hypothesis that radial Discussion- closed wedge osteotomy combined with osteochondroma resection improves the clinical and radiological outcome in this case Masada type 1 deformity (1) increase in the radial articular angle and ulnar variance (2) a decrease in radial ulnar length discrepancy (3) radial shortening (4) correction of carpal slip and bowing of the radius .The decrease in the radial ulnar length discrepancy produced by radial osteotomy probably prevented radial head dislocation because no episode of radial head dislocation was observed due to radial ulnar length discrepancy. This surgical technique is safe and reliable and no episode of necrosis or infection was observed while this technique probably stops the deformity from getting worse. While several treatment Conclusionoption are possible, it make sense to use a simple ,rapid procedure that is not associated with complication or pain-namely radial corrective osteotomy with osteochondroma resection- in children at the end of growth in whom the severe, progressive, radial deformities are associated with HMO.

Remodeling an existing rare disease registry to be used in regulatory context: Lessons learned and recommendations.

Disease registries have been used as an interesting source of real-world data for supporting regulatory decision-making. In fact, drug studies based on registries cover pre-approval investigation, registry randomized clinical trials, and post-authorization studies. This opportunity has been investigated particularly for rare diseases—conditions affecting a small number of individuals worldwide—that represent a peculiar scenario. Several guidelines, concepts, suggestions, and laws are already available to support the design or improvement of a rare disease registry, opening the way for implementation of a registry capable of managing regulatory purposes. The present study aims to highlight the key stages performed for remodeling the existing Registry of Multiple Osteochondromas—REM into a tool consistent with EMA observations and recommendations, as well as to lead the readers through the entire adapting, remodeling, and optimizing process. The process included a variety of procedures that can be summarized into three closely related categories: semantic interoperability, data quality, and governance. At first, we strengthened interoperability within the REM registry by integrating ontologies and standards for proper data collection, in accordance with FAIR principles. Second, to increase data quality, we added additional parameters and domains and double-checked to limit human error to a bare minimum. Finally, we established two-level governance that has increased the visibility for the scientific community and for patients and carers. In conclusion, our remodeled REM registry fits with most of the scientific community’s needs and indications, as well as the best techniques for providing real-world evidence for regulatory aspects.

Multiple Intraarticular Osteochondromas of the Knee

Osteochondroma is the most common benign growing bone tumor that usually affects the knee joint area. It often involves the long bone metaphysis, which occurs extraarticularly. Despite this, single intraarticular osteochondroma is rarely reported in the literature, but multiple knee osteochondromas is very rare and has not been reported so far. The patient who is introduced is a 30-year-old woman who has undergone two arthrotomy surgeries of the left knee, in which intraarticular osteochondroma was reported in the pathology. In the second operation, due to the size of the lesion and the involvement of the patella, the surgeon had to perform a patellectomy. The patient was referred with severe knee pain and inability to flexion and extension the knee and was unable to walk without a walker. Due to severe osteoarthritis and lack of extensor mechanism and condition of multiple intraarticular osteochondromas of the knee, complete excision of multiple osteochondroma lesions was performed for the patient and Rotating Hinge Knee (RHK) prosthesis was implanted. During two years of treatment follow-up, there is no recurrence of the lesion and the patient walks without a walker and is able to flex the knee 100 degrees. Her knee pain was also relieved.

Distraction osteogenesis at the proximal third of the ulna for the treatment of Masada type I/IIb deformities in children with hereditary multiple exostoses: a retrospective review of twenty cases.

Ulna distraction by monolateral external fixator (MEFix) is a good option for the treatment of Masada type I and IIb deformities in children with hereditary multiple exostoses (HMEs). However, there is no consensus regarding where to perform ulnar osteotomy. Our hypothesis is that osteotomy at the proximal third of the ulna and progressive distraction with MEFix can simultaneously correct elbow and wrist deformities in patients with HME. We retrospectively reviewed patients with HME who underwent ulna distraction osteogenesis from June 2014 to March 2019. The carrying angle (CA), radial articular angle (RAA), ulnar variance (UV), radial variance (RV) and range of motion (ROM) of the affected forearm and elbow were clinically assessed before lengthening and at the last follow-up visit. The total ulna lengthening distance (LD) and radiographic outcome were also recorded. Nineteen patients (20 forearms) with HME aged 9.1 ± 2.4years at the time of surgery were retrospectively reviewed. The mean follow-up period was 26.1 ± 5.6months. There were 11 patients (12 forearms) with Masada type I deformities and eight patients (8 forearms) with Masada type IIb deformities. Patients with type IIb deformity had higher RV, lower CA values, less elbow flexion and forearm pronosupination than those with type I deformity (p < 0.05); RV was an independent risk factor for radial head dislocation, with the cut off at RV > 15.5mm. The mean LDs in patients with type I and type IIb deformities were 33.6 ± 6.6mm and 41.4 ± 5.4mm, respectively. The mean CA, UV, RV, forearm pronation and ulna deviation at the wrist improved significantly following surgery in all patients. In particular, five of eight patients (62.5%) with type IIb deformities had concentric reduction of the radiocapitellar joint, while no radial head subluxation was detected in patients with type I deformities at the last follow-up. Three complications were recorded: two pin-track infections and one delayed union. Distraction osteogenesis at the proximal third of the ulna provides satisfactory clinical and radiological outcomes in patients with Masada type I and IIb deformities. Early treatment of Masada type I deformities is indicated before progression to more complex type IIb deformities.

A RARE CASE OF HEREDITARY MULTIPLE EXOSTOSES

Background: A rare genetic condition, hereditary multiple exostoses (HME), follows the autosomal dominant pattern of inheritance. It is evident by multiple bony elevations on the appendicular skeleton by the age of 2 years. Case Report: Here, we present the 42-years-old patient known case of CKD presenting with uncontrolled hypertension and breathlessness; however, incidentally, it was noted that there is bilateral swelling in the knee and further investigated for X-ray and blood parameters. On assessing the similar pattern in family members, it was noted such swelling over the shoulder in the daughter and swelling in the wrist joint in the younger brother. Conclusion: Hereditary multiple osteochondromas are a hereditary ailment that should be studied. Despite tremendous advances in recent years, the intricacy and unresolved difficulties associated with HME remain a challenge for academics and physicians.

A patient with pseudohypoparathyroidism type 1A previously misdiagnosed as hereditary multiple exostosis: A case report

Pseudohypoparathyroidism type 1A (PHP1A), a rare hereditary disorder, is featured by end-organ resistance to parathyroid hormone and Albright's hereditary osteodystrophy. Heterozygous mutation of guanine nucleotide-binding protein α stimulating (GNAS) gene causes the half decreased bioactivity of the Gsα protein levels. Due to the diverse early clinical manifestations of PHP1A, a diagnosis of PHP1A is often easily overlooked and misdiagnosis or missed diagnosis is common. The present study described a girl who was initially diagnosed with hereditary multiple exostoses, but was afterwards confirmed with PHP1A. Moreover, genetic analysis indicated a new mutation (c2277deIC) of the gene.

Functional Impairment of Hip Joint and Activities of Daily Living Failure in Patients with Multiple Hereditary Exostoses.

In this study, we focused on the hip joints and examined pain and functional impairment, and their relationship with anatomical characteristics in MHE patients. Patients with MHE followed up in our hospital from January 2020 to December 2020 were enrolled. Clinical hip functional outcomes were evaluated using the Japanese Orthopedic Association (JOA) hip score and hip range of motion (ROM). Proximal femur geometric measurements were evaluated using radiography. A total of 39 patients (78 hips) with a median age of 25.6years and average JOA score of 94.0 ± 10.5 were included. Eight patients felt pain in their hip joints. The average ROM score was 18.2 ± 2.5, and 47.4% of the patients with MHE had ROM limitation. The average score of ability to walk was 19.6 ± 1.8, and three patients had some problems with walking. The average ADL score was 18.2 ± 2.5, and 51.3% of patients with MHE had some failures in ADL. The hip flexion and internal rotation were markedly restricted compared with the normal values. When patients were grouped according to their ADL scores, we found that the ADL failure group had a significantly lower ROM score than the no ADL failure group (p < 0.0001), and there were significant differences between the groups in terms of femoral neck widening (p = 0.0001). We found that half of MHE patients had some failures in their ADL due to hip functional impairment. The study results also suggest that femoral neck widening affected ADL failure and ROM limitation.

Conventional Chondrosarcoma with Clear Cell Features in the Rib: Report of Two Cases and Review of the Literature.

A subset of clear cell chondrosarcomas may contain focal areas of low-grade conventional chondrosarcoma; however, it is rare to find foci resembling clear cell chondrosarcoma admixed with areas otherwise typical conventional chondrosarcoma. We report two patients with conventional chondrosarcoma with clear cell features occurring in the rib, one in the setting of multiple hereditary exostoses (MHE) and the other without MHE. Both patients were found to have a destructive rib mass with a soft tissue component and underwent en bloc resection. Histologic examination revealed predominantly grade 2 conventional chondrosarcomas; however, multiple foci containing large cells with pale eosinophilic to clear cytoplasm, distinct cell borders, centrally located nuclei, and conspicuous nucleoli, resembling clear cell chondrosarcoma were identified throughout the specimen. The significance of clear cell features in an otherwise typical conventional chondrosarcoma, to our knowledge, is unknown and deserves recognition. Finally, these tumors highlight the need for careful histologic examination and proper classification as unexpected findings may impact management.

A case of a large pedunculated-type osteochondroma from late medieval Ilok, eastern Croatia: Bioarchaeological, paleoradiological and histological study

Osteochondroma or osteocartilaginous exostosis is one of the most common benign tumors of the bone. Causes for the disease are yet unknown, but there are indications that they may be linked to abnormality in the growth plate and possibly mutation in EXT1, EXT2 and EXT3 genes. Cases of reported osteochondromas range from prehistoric to contemporary examples, are not limited geographically, and no evidence for sex predominance has been reported.Here we present a unique case of large pedunculated-type osteochondroma on the right fibula of an adult female skeleton from the medieval site of Ilok-Krstbajer in eastern Croatia. In order to gain more insight into this pathological change we used holistic approach consisting of a combination of techniques that have not been used previously in the analysis of neoplasms from archaeological settings.The cauliflower-shaped growth is 50 mm long in sagittal and 57.41 mm in transverse diameter with the tumor exhibiting a bulbous, rough superior surface, and a flat, smoother inferior surface. The gross morphology of the tumor together with radiological and histopathological features support the diagnosis of a proximal fibular osteochondroma making it the first such case in an archaeological population. Based on archaeological context and similar clinical cases it seems that the presented osteochondroma did not have major impact on the life-quality of a woman affected by this pathology. The procedure used in this study is minimally invasive and highly accurate, and as such sets new analytical criteria for studies of ancient bone neoplasms.

Costal exostosis at risk of hepatic injury in a 10-year-old girl

Hereditary multiple exostosis (HME) is a rare skeletal genetic disorder with multiple and disseminated osteochondromas. Costal localization is found in 40% of cases. Surgery for asymptomatic lesions remains controversial, but some lesions can be life-threatening. We report the case of a 10-year-old girl with HME, who developed a sharp costal exostosis compressing the hepatic parenchyma, for which a prophylactic resection was decided. The complete excision of the lesion was performed through extraperitoneal approach under video-assisted laparoscopy control, without short- and mid-term complication. To our knowledge, our case is the first in the literature where exostosis threatens the hepatic parenchyma.

An Easy-to-Use Approach to Detect CNV From Targeted NGS Data: Identification of a Novel Pathogenic Variant in MO Disease.

BackgroundDespite the new next-generation sequencing (NGS) molecular approaches implemented the genetic testing in clinical diagnosis, copy number variation (CNV) detection from NGS data remains difficult mainly in the absence of bioinformatics personnel (not always available among laboratory resources) and when using very small gene panels that do not meet commercial software criteria. Furthermore, not all large deletions/duplications can be detected with the Multiplex Ligation-dependent Probe Amplification (MLPA) technique due to both the limitations of the methodology and no kits available for the most of genes.AimWe propose our experience regarding the identification of a novel large deletion in the context of a rare skeletal disease, multiple osteochondromas (MO), using and validating a user-friendly approach based on NGS coverage data, which does not require any dedicated software or specialized personnel.MethodsThe pipeline uses a simple algorithm comparing the normalized coverage of each amplicon with the mean normalized coverage of the same amplicon in a group of “wild-type” samples representing the baseline. It has been validated on 11 samples, previously analyzed by MLPA, and then applied on 20 patients with MO but negative for the presence of pathogenic variants in EXT1 or EXT2 genes. Sensitivity, specificity, and accuracy were evaluated.ResultsAll the 11 known CNVs (exon and multi-exon deletions) have been detected with a sensitivity of 97.5%. A novel EXT2 partial exonic deletion c. (744-122)-?_804+?del —out of the MLPA target regions— has been identified. The variant was confirmed by real-time quantitative Polymerase Chain Reaction (qPCR).ConclusionIn addition to enhancing the variant detection rate in MO molecular diagnosis, this easy-to-use approach for CNV detection can be easily extended to many other diagnostic fields—especially in resource-limited settings or very small gene panels. Notably, it also allows partial-exon deletion detection.

A Genotype-Phenotype Study of Multiple Hereditary Exostoses in Forty-Three Patients.

Multiple hereditary exostoses (MHE) is a rare autosomal dominant skeletal disorder with a variety of clinical manifestations. We aimed to evaluate the general clinical phenotypic severity of MHE using our own scoring system and analyzed the risk factors associated with severe clinical phenotypes. In this study, 43 patients from 30 families were analyzed. The mutations were identified by direct sequencing of polymerase chain reaction-amplified genomic DNA or by multiplex ligation-dependent probe amplification. According to a new scoring system devised by the authors, the severity of the phenotype was assessed as mild, moderate, or severe based on the deformity of each segment, number of exostoses, leg length discrepancy, and functional limitations. Of 43 patients from 30 families, 39 patients (90.7%) and 24 families (80%) presented with EXT1 or EXT2 mutations. Patients with EXT1 mutations had a significantly worse phenotype than that of patients with EXT2 mutations or without any detectable mutation. The mean clinical score of patients with an EXT1 mutation (5.76; range, 2.0–8.0; SD = 1.60) was higher than that of patients with an EXT2 mutation (4.06; range, 2.0–7.0; SD = 1.47) or of those without any detectable mutation (4.63; range, 3.0–6.0; SD = 1.44; p = 0.005). According to our classification system, more patients with EXT1 mutations had ‘severe disease’ than those with EXT2 mutations. Deformity scores were also higher in patients with EXT1 mutations (p = 0.018). In the multivariate analysis, the deformity score was found to be associated with the ‘severe’ class (p = 0.031). In conclusion, 90.7% of patients with MHE showed EXT mutations. Our scoring system showed reliable results. We suggest that the extent of deformity is an important factor in determining the phenotype of MHE and close monitoring for the development of severe disease is recommended in patients with high deformity scores.

The Impact of Isolated Versus Multiple Osteochondromas: Analysis of the CoULD Registry.

The burden of upper extremity (UE) osteochondromas on function and self-perception among pediatric patients is unclear. The purpose of our study was to study the impact of osteochondromas in comparison to population norms and to evaluate solitary versus multiple osteochondromas on subjective UE function as measured by patient rated outcomes. We utilized the CoULD (Congenital Upper Limb Differences) Registry to review all pediatric patients presenting with osteochondromas between January 2014 and February 2021. Demographic information was collected and patients were classified as having either single or multiple osteochondromas. Patient-Reported Outcome Measurement Information System (PROMIS) and Pediatric Outcomes Data Collection Instrument (PODCI) tools were utilized for assessment. Scores for PODCI subscales of UE function, Pain/comfort, and Happiness and PROMIS domains of UE Function, Pain, Depression, Anxiety, and Peer Relations were reviewed. Differences between groups were analyzed using the Student t test. Ninety-nine patients met inclusion criteria for the study with an average age of presentation of 9.3 years and 61 patients (62%) were male. Overall, patients demonstrated worse UE Function as well as greater Anxiety and Depression in comparison to the population normals on PROMIS assessment. Patients also demonstrated worse patient and parent reported PODCI UE, Sports and Physical Functioning, Pain/Comfort and Global Functioning scores compared with population norms but demonstrated better than average happiness scores. Patients with multiple osteochondromas demonstrated greater PROMIS pain interference and more disability in PODCI Sports and Physical Functioning, Pain/Comfort and Global Functioning compared with those with solitary osteochondromas. Patients with UE osteochondromas have worse overall function in comparison to population norms, exceeding established minimally clinically important difference values. In addition, patients with multiple osteochondromas reported more pain and poorer physical function than those with solitary osteochondromas. Physicians should be alert to the physical and psychosocial burden of this disease. Level II-prognostic.

Total Knee Arthroplasty With Patient-Specific Instrumentation to Correct Severe Valgus Deformity in a Patient With Hereditary Multiple Exostoses

Patients with hereditary multiple exostosis develop several benign osseocartilaginous bulge lesions throughout the body. A 62-year-old woman presented for evaluation of worsening left knee valgus deformity, and left knee pain. She had been diagnosed with hereditary multiple exostosis at the age of 12 years. Radiographic evaluation of the left knee revealed exostoses that caused continuous bulges from cortical bone at the metaphyseal regions of the femur and tibia as well as extra-articular deformity. We used patient-specific instrumentation to indicate the direction of the stem into curved metaphyseal bone regions and then corrected the patient’s left knee deformity by performing total knee arthroplasty with titanium-constrained prostheses. Soft tissue release was performed with only complete iliotibial band release at a minimum, and stability was obtained.

Forearm Hereditary Multiple Exostosis: A Retrospective Case Series Study.

BackgroundHereditary multiple exostosis (HME) is a significantly rare genetic condition with benign chondrogenic lesions affecting long bones. Forearm involvement is relatively common, with varied treatment modalities reported. Here we describe our experience with HME. The study is the first of its kind to be conducted in the Middle East and Saudi Arabia.MethodsA retrospective medical record-based case review was carried out on patients with forearm HME operated from 2006 to 2022 at our institution. Patient demographics, clinical presentation, management, outcome, Masada scale, and radiological outcomes were analysed. ResultsTen patients (12 affected forearms) with HME were included. The average age of those undergoing surgery was 12.7 ± 5.13 years, and the average length of follow-up was 62.25 months. Most patients (n = 5, 50%) had Masada type 1 (Type I indicates radial head not displaced, primary exostosis from the distal region of the ulna, ulna relatively short, radius bending). Five (50%) underwent radial head resection. The majority of the patients (n = 8, 80%) had no complications or recurrence. Two patients developed recurrence; the first one developed recurrent radial bone deformity and dislocation of the radial head and the second, who underwent excision with an iliac crest bone graft application, developed osteolysis of the bone graft with recurrent deformity.ConclusionHME is typically managed primarily by excision of the lesion at skeletal maturity and annual check-up and radiological follow-up. If a secondary procedure is needed in future, simple excision of the dislocated radial head would be the most feasible approach. Due to the rarity of the illness and limited literature, further studies are still required to optimize the outcome in children with HME.

Real-World Data and Budget Impact Analysis (BIA): Evaluation of a Targeted Next-Generation Sequencing Diagnostic Approach in Two Orthopedic Rare Diseases.

Objective: Next-generation sequencing (NGS) technology, changing the diagnostic approach, has become essential in clinical settings, and its adoption by public health laboratories is now the practice. Despite this, as technological innovations, its intake requires an evaluation of both the clinical utility and the economic investment, especially considering the rare disease scenario. This study evaluated the analytical validity and the budget impact of an NGS-Ion Torrent™ approach for the molecular germline diagnosis of two musculoskeletal rare diseases. Methods: Two cohorts of 200 and 199 patients with suspect or clinical diagnosis of multiple osteochondromas (MO) and osteogenesis imperfecta (OI) previously evaluated with a single-gene diagnostic protocol were re-analyzed using a targeted NGS assay. Analytical validity was assessed by comparing NGS and single-gene protocol. A budget impact analysis using real-world cost data-considering the healthcare perspective— was performed by applying activity-based costing (ABC). The cost considered consumables, personnel, and equipment. Additional costs not related to NGS activities were not considered. Sensitivity analysis was performed. Results: The NGS method showed a higher (for MO) and comparable (for OI) diagnostic sensitivity than the traditional techniques, apart from always reducing the time and costs of diagnosis. Overall, the cost saving per patient is € 765 for OI and € 74 for MO. Materials represented the highest cost driver of the NGS process. A time saving—proportional to the panel size—has been assessed in both cases. Conclusions: Our targeted NGS diagnostic approach decreases time to diagnosis and costs, appearing to be beneficial and recommended both for patients and from a healthcare perspective in routine diagnosis also considering very small gene panels and a low patient flow. The adequate analytical sensitivity always required the additional Sanger sequencing step of the low- and non-covered regions. A more accurate strategy evaluation is suggested in the case of ultra-rare/complex diseases, large gene-panel, or non-reference diagnostic centers.

Symptomatic osteochondroma of the chest wall

Hereditary multiple exostosis (HME) is a rare skeletal disease in children characterized by the formation of benign tumors near bone growth plates. The metaphysis of long bones is most commonly affected, with a predilection for the distal femur, proximal tibia, and proximal humerus. It is uncommonly found on the scapulae's vertebral borders, iliac crests, and ribs. We present a 2.5-year-old child with a history of several tumors on his body, the largest of which measured 95 × 55 × 40 mm on the 8th rib on the right side of the chest wall. This tumor was painful, but there were no injuries to the intrathoracic contents. HME was confirmed based on clinical examination, family history, radiographic examination, and histological examination. It was completely excised along with another painful tumor on the right scapula. The child was discharged in good health after 4 days postoperatively without any problems with follow-up. Because the risk of malignant transformation increases as these tumors grow in size and cause pain, especially at this age, surgical removal was required.

Computer Navigation-Aided Excision of Proximal Femoral Osteochondroma: Surgical Technique.

Purpose Symptomatic osteochondroma of the proximal femur necessitates a surgical excision. The purpose of this study was to describe a novel technique of computer navigation-aided excision for osteochondromata of the proximal femur. Outcomes of this technique are also presented. Methods A total of 13 patients underwent computer navigation-aided excision of osteochondromata of the proximal femur from February 2012 to August 2016 in our institution. They were enrolled in this study. OrthoMap 3D (Stryker Orthopaedics, Mahwah, NJ, USA), a commercially available navigation software system, was used to merge computed tomography images of the proximal femur with an osteochondromata with the image of a normal proximal femur. Using the normal proximal femur as a template, intended resection margins for the proximal femur with osteochondromata were planned and then executed using intraoperative navigation guidance. Patients were followed up clinically and radiographically. The physical and mental health of patients was assessed with the Musculoskeletal Tumor Society (MSTS) score. Results Eight patients had isolated exostoses. Five patients had tumors associated with multiple hereditary exostoses. For tumors projecting posteriorly or posteromedially, a posterolateral approach was used. For tumors projecting anteriorly or medially, an anterior approach was used. Prophylactic fixation was performed in four patients who required an anterior approach. The mean duration of the surgery was 189 minutes. There were no intraoperative fractures or postoperative complications. A secondary procedure was not needed for any case. The mean MSTS score at a mean follow-up of 17 months was 28.6 (maximum MSTS score: 30). Conclusions This is the first study to report a novel application of computer navigation for aiding the excision of osteochondromata of the proximal femur. It demonstrated favorable postoperative functional scores with a low rate of complications. The applicability, safety, and efficacy of this technique were demonstrated. It is particularly useful for resections involving large tumors that can obscure anatomical landmarks and for patients with associated proximal femoral deformity.