Introduction. Ascertaining the etiology of hip pain in young patients can be challenging. Osteoid osteoma about the hip has only been described in case reports and small case series in this sub-population. This study assessed the clinical course, radiologic findings, and treatment approaches in a large series of pediatric osteoid osteoma cases about the hip. Potential diagnostic and treatment pitfalls were identified. Methods. A single-center tertiary care departmental database was queried for all cases of osteoid osteoma seen between Jan 1, 2003 and December 31, 2015. Medical records were reviewed to identify those with lesions identified within or around the hip joint. Clinical, demographic, and radiologic data were analyzed. Results. Fifty children and adolescents (56% female, mean age 12.4 years, range 3–19 years) were identified with osteoid osteoma about the hip. The femoral neck was the most common lesion location (38%), and pain in the hip was the most common presenting chief complaint (60%). Night pain (90%) and symptom relief with NSAIDs (88%) were extremely common, though not universally reported. Sclerosis and/or cortical thickening was visible in 58% of radiographs, though a lucent nidus was visible in only 42%. Thirty patients (60%) underwent MRI, 27 of which were available for review, with focal peri-lesional edema as a universal finding. Amongst intracapsular lesions (n=17, 63%), common findings included medial retinacular thickening (33%), synovitis (45%) and effusion (76%). In the 43 patients (48%) who underwent CT, a diagnostic lucent nidus was a universal finding. Initial alternative diagnoses were recorded in 46% of cases, including, in order of decreasing frequency, femoro-acetabular impingement, minor trauma, hip synovitis, ‘growing pain’, stress fracture, and infection. Abnormal hip range of motion, positive impingement signs, and global synovitis on MRI scan were found to be associated with alternative diagnosis. On multivariate regression analysis, only abnormal hip ROM was independently predictive of alternative diagnosis. Delay in diagnosis of >6 months was seen in 43% of patients. Three patients underwent preceding operative procedures for other hip diagnoses, but had persistent hip pain until the osteoid osteoma was treated. Forty-one patients (82%) ultimately underwent radiofrequency ablation (RFA), and 1 open osteoid osteoma resection was performed. Of those who underwent RFA, 93% achieved complete symptom resolution, with 2 of 3 patients without symptom resolution undergoing revision RFA procedure, 1 of which led to symptom resolution. Complications of treatment included 1 case of deep infection along an RFA track, requiring operative debridement, 1 case of transient weakness and paresthesias in the involved extremity, and 1 case of fracture at the RFA site, requiring ORIF. Conclusions. Alternative andelayed diagnoses are common in osteoid osteoma about the hip, with femoro-acetabular impingement representing the most common alternative initial diagnosis in our series. While varying presenting complaints and nonspecific MRI findings may contribute to diagnostic uncertainty, night pain was present in the vast majority of cases and CT scans provided definitive diagnosis in all patients who received them. As increasing numbers of young, active patients are being evaluated for various causes of hip pain, such as femoro-acetabular impingement, osteoid osteoma should not be overlooked in the differential diagnosis of pain about the hip

This study was designed to be the first to prospectively evaluate CT-guided radiofrequency ablation for osteoid osteoma in terms of pain control, medication consumption, quality of life and patient function. Over two years, forty patients with symptoms and radiographic findings classic for osteoid osteoma were offered radioablation. Patients were asked to fill out facial, subjective and visual analog pain scales and to undergo the Musculoskeletal Tumour Society 1987 functional assessment. Results show immediate and lasting resolution of symptoms, a sharp drop in drug use and a significant improvement in function thus supporting the role of radioablation as first line therapy. The purpose of this study was to prospectively evaluate the usefulness of radioablation for osteoid osteoma in terms of pain control, analgesic drug consumption, quality of life and patient function. Radioablation appears to be a safe and effective method of treatment for osteoid osteoma. It offers immediate and lasting resolution of symptoms. Results support its role as first line therapy. This is the first study to prospectively measure the outcome of patients treated with CT-guided radiofrequency ablation for osteoid osteoma. The mean follow-up time is 6.93 months (sd: 6.51). All but seven procedures were done under regional anaesthesia. No complications were reported. 50% of core biopsy specimens were diagnostic of osteoid osteoma. The visual analog pain scale showed a value of 2.13(sd: 2.5) pre-op and 0.33(sd: 1.07) at 1 year (p=0.00033). The MSTS score rose from 28.86(sd: 4.68) pre-operatively to 34.06(sd: 1.95) after one year (p=0.000000049). Medication consumption was markedly reduced. All eighteen patients with more than one- year follow-up are drug free. Over two years, forty patients with symptoms and radiographic findings classic for osteoid osteoma who had already received various treatments were offered radioablation. Written consent was obtained and patients were asked to fill out facial, subjective and visual analog pain scales. The Musculoskeletal Tumour Society 1987 functional assessment was performed. This data was collected two weeks prior to treatment and then at two weeks, three months and one year after treatment. The procedure was performed under CT guidance and on a one-day hospital admission basis

Radiofrequency ablation (RFA) is a relatively new technique to produce cell death by radiowaves (460– 480 kHz) caused by an alternating current emitted from the tip of a needle electrode and causing local ions vibration producing heat. In orthopaedic fields RFA has been proposed for the treatment of osteoid osteoma and painful metastases. Methods: 121 patients with a clinical and radiographic accerted osteoid osteoma have been treated with percutaneous radiofrequency ablation at our institutions from 1998 till December 2005. Average age of the patients was 23 years. Preoperative symptoms lasted 10 months on average. The osteoid osteoma was localized at the limbs in 111 cases, at the pelvis in 4 cases and at the spine in 6 cases. Results: At follow up we had 3 cases of recurrences and 2 fair results with a total of 5 unsuccessful cases. The fair results were due to a mistake of radiological indication and one case of ineffectively ablation. We observed 3 cases of skin burns in tibia with superficial infections: 2 cases resolved without treatment while the latter case showed initial bone infection and needed surgical revision. Conclusion: Percutaneous RFA of osteoid osteoma proved to be a successful treatment in more than 95% of the cases with a low complication rate

Study Design: Prospective cohort study. Objective: To assess the safety and efficacy of an intra-operative gamma probe in the surgical treatment of osteoid osteomas and osteoblastomas arising from the spine. Summary of background data: Spinal osteoid osteomas and osteoblastomas are difficult to localise and may present adjacent to neural structures. Complete surgical excision of the nidus is a pre-requisite for curative resection. Methods: All patients with a presumptive diagnosis of osteoid osteoma or osteoblastoma were investigated with plain radiography, computed tomography, magnetic resonance imaging and a technitium bone scan. Nine patients underwent surgical excision. 600 MBq of 99m technitium HMDP was administered intravenously three hours prior to surgery. A sterile cadmium telluride detector connected to a digital counter/ratemeter was used to detect gamma radiation emitted by the tumour intra-operatively to assist with localisation and confirmation of complete excision. Results: Between October 1995 and September 2006, nine patients required surgical excision for seven osteoid osteomas and two osteoblastomas arising from the spine. All patients were between the ages of 9–31 years and presented with back or neck pain. All tumours involved the posterior elements of the spine. Three patients had previous failed treatment including CT-guided radiofrequency ablation and surgical excision. In all cases the counts per second (cps) dropped significantly following excision. For the osteoid osteoma cases, the mean cps dropped from 203.8 (range 60–515) to 72.5 cps (range 10–220) post-excision. For the osteoblastoma cases the mean cps dropped from 373.5 (range 67–680) to 40.5 cps (range 16–65) post-excision. Histological examination confirmed complete excision in all cases. The mean follow-up was 4.5 years (range 0.5 – 11 years). All patients reported disappearance of the characteristic pre-operative pain. Conclusions: The use of an intra-operative gamma probe helps to localise and confirm complete excision of osteoid osteoma and osteoblastoma arising from the spine. Accurate localisation results in safe excision with maximal conservation of surrounding normal bone, whilst minimising operative time, blood loss, hospital stay and risk of recurrence

Study Design. Prospective cohort study. Objective. To assess the safety and efficacy of an intra-operative gamma probe in the surgical treatment of osteoid osteomas and osteoblastomas arising from the spine. Summary of background data. Spinal osteoid osteomas and osteoblastomas are difficult to localise and may present adjacent to neural structures. Complete surgical excision of the nidus is a pre-requisite for curative resection. Methods. All patients with a presumptive diagnosis of osteoid osteoma or osteoblastoma were investigated with plain radiography, computed tomography, magnetic resonance imaging and a technitium bone scan. Nine patients underwent surgical excision. 600 MBq of 99m technitium HMDP was administered intravenously three hours prior to surgery. A sterile cadmium telluride detector connected to a digital counter/ratemeter was used to detect gamma radiation emitted by the tumour intra-operatively to assist with localisation and confirmation of complete excision. Results. Between October 1995 and September 2006, nine patients required surgical excision for seven osteoid osteomas and two osteoblastomas arising from the spine. All patients were between the ages of 9-31 years and presented with back or neck pain. All tumours involved the posterior elements of the spine. Three patients had previous failed treatment including CT-guided radiofrequency ablation and surgical excision. In all cases the counts per second (cps) dropped significantly following excision. Histological examination confirmed complete excision in all cases. The mean follow-up was 4.5 years (range 0.5-11 years). All patients reported disappearance of the characteristic pre-operative pain. Conclusions. The use of an intra-operative gamma probe helps to localise and confirm complete excision of osteoid osteoma and osteoblastoma arising from the spine. Accurate localisation results in safe excision with maximal conservation of surrounding normal bone, whilst minimising operative time, blood loss, hospital stay and risk of recurrence

The recognition, investigation and management of osteoid osteoma has been well documented. Treatment can either be medical or surgical, studies have shown both options to have almost equal long term outcomes. However only surgical treatment involving complete excision of the lesion allows for confirmatory tissue diagnosis of osteoid osteoma especially important in cases where symptoms and signs are atypical. Several methods of surgical treatment with varying degrees of success have been described in literature. Here we describe a surgical techniques for the treatment of osteoid osteoma which enables removal of the lesion in a precise manner using a precision bone graft trephine with minimal excision of bone. This technique will be very useful in the excision of lesions in areas in which excessive excision of bone can lead to an unstable bony structure which can predispose to fracture. To our knowledge this surgical technique in the management of osteoid osteoma has not been described in the literature

Osteoid osteoma is a benign bone tumor usually observed in children and adults, generally in the femur or tibia. Pain relief with aspirin is a classical clinical characteristic. Computed tomography is the exploration of choice providing reliable diagnosis. Cure can be achieved with surgical resection. We present an exceptional case of osteoid osteoma located in the patella

Osteoid osteoma is a benign bone-forming lesion, characterized by its small size, its clearly demarcated outline and by the usual presence of a surrounding zone of reactive bone formation. It often poses a diagnostic challenge due to its ambiguous presentation. The aetiology of osteoid osteoma is poorly understood. The previous suggestion that osteoid osteoma was not associated with trauma or infection has been challenged by more recent literature raising the possibility that it could be a reactive or healing response or a phenomenon associated with the revascularisation process. This case report describes an unusual presentation of a post-traumatic osteoid osteoma. Two years following a diaphyseal, spiral tibial fracture treated nonoperatively, the patient developed new pain at the previous fracture site. The pain was constant, relieved by non-steroidal analgesia and not associated with systemic upset. It was initially attributed to other more likely diagnoses such as osteomyelitis and neuropathic pain. Multiple investigations and interventions were undertaken prior to the definitive diagnosis being obtained by surgical excision of the lesion and histological studies five years after the injury and three years following the initiation of the discomfort. In both English and foreign language literature there are only seven case reports that document osteoid osteoma following fracture, these are predominantly in the lower limb with no predominance to operative or nonoperative management. This case report should raise the index of clinical suspicion of osteoid osteoma occurring post fracture

Osteoid osteoma is a classically described benign bone tumour. Traditionally, the surgical treatment of choice was excision, but this can have significant morbidity. In recent years, percutaneous Radiofrequency Ablation (RFA) has grown in popularity as an alternative treatment. This study reports the outcomes using this technique in our regional bone tumour unit. Between May 2003 and October 2007, 14 patients (female, n=4; male, n = 10) aged 15 - 32yrs (mean age, 20.4yrs) underwent CT guided radiofrequency ablation treatment. These patients had typical radiograph, CT, MRI or isotope bone scan features of osteoid osteoma and had significant pain symptoms. The protocol for ablation in our institute is heating the tip of the electrode to 90°C for 6 minutes. All patients were subsequently offered follow up in the out-patient clinic. Outcomes were taken from the Scottish Bone Tumour Registry database. 11 patients (78.6%) patients had complete resolution of symptoms after one RF treatment. 3 (21.4%) cases were unsuccessful but 1 of these was due to technical failure. All 3 of the above patients had complete relief of symptoms after one further RF treatment. 1 (7.1%) patient initially had complete relief of symptoms, but suffered a recurrence after 9 months. This patient also had a second curative treatment. Follow up ranged from 3 – 18 months (mean 10 months). Percutaneous RFA for osteoid osteoma is an attractive treatment due to its efficacy and low morbidity. Our results showed a primary success rate of 78%, a secondary success rate of 100% (after one additional procedure) and a recurrence rate of 7.1%. These are comparable to previous reported series. We believe our results add to the growing literature supporting radiofrequency ablation as the treatment of choice for osteoid osteoma

The aim of our study is to present osteoid osteoma as a disease in preschool children. O O is a benign inflammatory process that is characterized from osteoid formation. It appears mainly in the second and third decade of life, while before 5 years of age usually as case reports. The clinical and radiological presentation must be differentiated from trauma, osteomyelitis, malignancy and other benign diseases. We present three patients, aged ranging from 18 months to 4 years old, that were treated surgically for the removal of O O in the tibia and fibula. All patients presented with limping, pain mainly in the night, gradual restriction of activities. The clinical, hematological and radiological investigation revealed the general aspects of the disease. Bone scans were positive in all. CT scan confirmed the diagnosis in all three patients. Surgical treatment was done with fluoroscopic assistance, in order to remove the minimum possible amount of bone. In two patients the lesion was located in the distal metaphysis of the tibia and in one in the distal metaphysis of the fibula. The diagnosis was confirmed with the typical nidus, in pathological specimens. In one patient the lesion was intracortical and in two in the medullary area. Despite the ages of our patients, there were not misleading findings, in the specimens. After surgery the patients were symptoms free, and with 1–4 years follow up, there are no recurrences. We conclude that osteoid osteoma must be included in the differential diagnosis, in cases of pain and limping, in preschool children

Introduction: Osteoid osteoma is a benign tumour that usually requires surgical excision as it commonly presents with severe and debilitating pain. Treatment by percutaneous drill resection with CTscan control was developed by Doyle, Voto & Kohler 15 years ago as an alternative to the classical “en bloc resection”. A series of 62 cases using this method is reported. Method: The procedure is performed by an orthopaedic surgeon in the CT Scan room with the radiologist participation. The lesion (nidus) is localized on an appropriate CT slice. A special set of instruments (drill, trephine, reamer) are introduced in succession along a guide wire through a short skin incision. A small cylinder of bone is removed for histopathology analysis. Between June 1987 and July 2003, 62 cases were so far treated. There were 13 adults (19 – 35 years) and 49 children and adolescents (2.5 years – 18 years). All patients had a clinical and radiological evidence for osteoid osteoma (hyperfixation on scintigraphy, visible nidus on CT scan). The nidus was mostly localized in the lower limb (53 cases) especially femoral neck (23), femoral shaft (13), tibial shaft (14). Results: No severe complications were observed (delayed union after skin necrosis of the tibia in 3 cases, transitory palsy of extensor hallucis longus in one case. Clinical healing after a 1 year follow up was observed in all but 2 cases. In these 2 cases the lack of healing was considered as a failure of treatment and not true “recurrence”; a second attempt was successful. The nidus was confirmed in the specimen in half cases. Discussion: This method has now clearly demonstrated its effectiveness and security. Benefits for patients are evident: thanks to minimal bone resection, quick recovery and immediate weight bearing are possible. This technique is now indicated in most cases, versus “en bloc resection” which should be considered only for some vertebral or superficial localizations of the nidus. Concurrently, other techniques have been recently developed : destruction by thermo coagulation or photocoagulation, which are similar to resection ; all are non invasive interventional procedure

Introduction: Osteoid Osteomas are not uncommon, benign bone tumours which have well-defined clinical, radiological and pathological characteristics. These tumours can potentially affect any bone in the body, but show a predilection for long tubular bones. The clinical presentation can easily be confusing, if the site in question is rare and the presentation atypical. Lesions occurring in the foot often pose particular problems in diagnosis, often leading to delays in treatment. Although there have been accounts of the post traumatic presentations of osteoid osteomas, no direct link has been established between trauma and its incidence. Case Report: A 38 year old gentleman was referred by his GP with an eighteen month history of right midfoot pain after a football injury which forced his right foot into hyperextension and abduction. Initial radiographs after the injury were normal. The pain did not respond to non-steroidal anti-inflammatory drugs (NSAIDs) and there were no nocturnal exacerbations. Examination at presentation showed an antalgic gait with medial mid-foot tenderness centred over the first tarso-metatarsal joint (TMTJ). Repeat radiographs showed mild degenerative changes in the first TMTJ. A bone scan showed a hot spot over the right cuneiform bones. Subsequent computed tomography (CT) showed an osteoid osteoma, with a characteristic central calcific nucleus within the nidus, of the medial border of the lateral cuneiform bone. The osteoma was treated with en-bloc excision and the diagnosis was confirmed by histology. Conclusion: Despite the advances in its treatment, osteoid osteoma of the foot can pose a difficult diagnostic puzzle. This condition should always be kept in mind when faced with persistent, post-traumatic foot pain, even in the absence of roentgenographic findings. In such cases a high index of suspicion and a low threshold for appropriate imaging can lead to the timely diagnosis and treatment of this tumour

Purpose: The purpose of this study was to assess the safety and efficacy of computed tomography (CT) guided percutaneous radiofrequency (RF) ablation of osteoid osteoma by using the water-cooled probe. Patients & Methods: During the period from July 2002 to February 2006, fifty-one patients with osteoid osteomas localized in femur (30), tibia (9), calcaneus (2), talus (2), metatarsus (2), humerus (1), sacrum (1), scapula (1), olecranon (1), patella (1) and thoracic vertebra (1) were treated with CT-guided RF ablation using the Cooltip™ Tyco Healthcare probe. Mean age was 20 (range, 3.5 to 57) and male to female ratio was 35/16. Mean follow-up period was reported 22 months (range, 8 to 50 months). The procedures were carried out under general anesthesia and the patients were discharged from the hospital within 24 hours. Results: Technically, all the procedures were performed successfully. Pain disappeared postoperatively in all the patients within 2–3 days and no patients needed analgesic treatment after a week. All patients were allowed fully weight bear and function without limitation after the procedure. Recurrence of the pain was observed in one patient who was treated successfully with a second ablation. Our primary and secondary clinical success rates were 98% and 100% respectively. In one case, wound infection was observed after the procedure as the only post-operative complication in our series. Conclusion: CT-guided percutaneous RF ablation of osteoid osteomas using the water-cooled probe is a safe, effective and minimally invasive procedure with high success rate and lack of relapses

Purpose: The relationship between pain, quality of life (QOL) anxiety and depression in patients with chronic pain is complex. The aim of this study was focused in osteoid osteomas which treated with Radiofrequency thermal ablation (RFTA). Patients and Methods: We determine the pain characteristics severity, duration, meaning of pain, (MINESOTA score), psychological distress (HADS), physical functioning, social functioning and quality of life (SF −36) and determine which of these variables improved after Radiofrequency thermal ablation in osteoid osteomas. A total of 26 patients with osteoid osteoma which proceed in RFTA and completed the questionnaires, evaluated pain, quality of life, anxiety, depression, physical functioning, and social functioning before and after the procedure in a mean follow up of 17 months. Pearson correlation coefficients were calculated to examine the relationships among the study variables. A multiple regression analysis was performed to determine which variables were the most important predictors. Results: Pain was significantly correlated with all the other variables, in particular depression and anxiety. Pain QuoL and Depression improved dramatically after kyphoplasties in a follow up of 17 months period. Conclusion: The clinical results indicate a 100% success rate with complete remission of symptoms and no relapses having been reported at the time of those patients who have arrived at the one year follow up. CT-guided RF ablation is a safe, simple and effective method of treatment for osteoid osteoma. and improve quality of life, anxiety and depression in these patients

Osteoid osteomas are benign, painful osteogenic tumours of small size (≤ 1,5 cm). Surgical resection of the nidus has been the elected method of treatment for decades but some complications and difficulties (poor localization, extensive tissue damage, fractures, delayed recovery) encouraged the development of less invasive techniques such as radiofrequency. Lack of histological proof is the major concern regarding radiofrequency ablation as we make the diagnosis by the clinical findings and the image features. We present the results of 20 patients with osteoid osteoma treated with radiofrequency from January 2004 to December 2008 (mean follow up 23 months). All patients were under general anaesthesia and de access route was chosen in the CT-suite. 11 cases were located in the proximal femur (head, neck and subtrocanteric region), 2 in the distal femur, 2 in de distal humerus, 2 in the tibia, 2 in the acetabulum, and 1 in de vertebal body of D8. In all cases we used a Cool-tip TM RF electrode (water-cooled tip) reaching a heating temperature of 42°C to 48°C during 12 minutes. In 7 patients a cannulated drill bit was used to penetrate the thick cortical or to reach the nidus through the opposite side in order to avoid a neurovascular bundle. Hospital discharge was allowed after 6 to 8 hours after the procedure. No complications occurred. All patients, except one, experienced complete relief of the pain although the 6-month follow-up CT’s do not show sclerosis of the nidus. None of them recurred till data. The patient who did not recover had not had a clear diagnosis. We conclude that radiofrequency ablation is effective, safe, favouring rapid recovery and, of course, reduces economical and social costs

Purpose: To report our experience in diagnosis and treatment of Osteoid Osteoma in the foot and ankle. Material and Methods: Six patients, 4 males and 2 females, mean age 24 (range 17–40), were diagnosed, suffering of osteoid osteoma of the foot and ankle in our outpatients clinic. All the patients had typical spontaneous pain and night pain improved by NSAIDs. In all patients, the diagnosis was delayed for one – two years. Treatment by Computed Tomography guided percutaneous radiofrequency ablation was performed in 4 patients, one patient underwent CT guided curettage and one underwent open excision and local bone graft of the lesion. In patients treated by RF, the lesions were heated three times to 90° for 2 minutes. All the procedures were done under ankle block and local anesthesia. Patients were evaluated in our outpatients foot and ankle clinic 1–2 years following the procedure. Results: The Osteoid Osteoma was found in the talus of two patients and one in the cuboid, one in the base of third metatarsus, one in the calcaneus and one in the ankle. In all patients most of the pain was resolved within 3 days of the procedure. In 3 patients after a year there was still mild pain at tremendous physical efforts attributed to minimal damage to adjacent joint. Three patients completely recovered including pain free physical efforts. CT at follow-up in 2 patients revealed no pathology of the involved bones. Conclusions: OO is an uncommon affection in the foot and ankle. The diagnosis is difficult and usually there is delayed. CT guided percutaneous radiofrequency of the foot is a safe and effective. The procedure can be performed under ankle block and local anesthesia

The primary aim of this study was to compare the clinical outcomes of osteoid osteoma (OO) between the group of patients with the presence of nidus on biopsy samples from radiofrequency ablation (RFA) with those without nidus. Secondly, we aimed to examine other factors that may affect the outcomes of OO reflecting our experience as a tertiary orthopaedic oncology centre. We retrospectively reviewed 88 consecutive patients diagnosed with OO treated with RFA between November 2005 and March 2015, consisting of 63 males (72%) and 25 females (28%). Sixty-six patients (75%) had nidus present in their biopsy samples. Patients’ mean age was 17.6 years (4-53). Median duration of follow-up was 12.5 months (6-20.8). Lesions were located in the appendicular skeleton in seventy-nine patients (90%) while nine patients (10%) had an OO in the axial skeleton. Outcomes assessed were based on patients’ pain alleviation (partial, complete, or no pain improvement) and the need for further interventions. Pain improvement in the patient group with nidus in histology sample was significantly better than the group without nidus (OR 7.4, CI 1.35-41.4, p=0.021). The patient group with nidus on biopsy demonstrated less likelihood of having a repeat procedure compared to the group without nidus (OR 0.092, CI 0.016-0.542, p=0.008). Our study showed significantly better outcomes in pain improvement in appendicular lesions compared to the axially located lesions (p = 0.005). Patients with spinal lesions tend to have relatively poor pain relief than those with appendicular or pelvic lesions (p=0.007). Patients with nidus on histology had better pain alleviation compared to patients without nidus. The histological presence of nidus significantly reduces the chance of repeat interventions. The pain alleviation of OO following RFA is better in patients with appendicular lesions than spinal or axially located lesions

Failures of treatment of osteoid osteoma (OO) are related to errors in exact localization and incomplete excision of the nidus. Intraoperative Iso-C 3D navigation allows exact localization, excision and confirmation of excision by percutaneous methods. We report the successful percutaneous excision of OO in 11 patients (extremities-5; spine-6). All patients had a minimally invasive reflective array (MIRA) fixed to the same bone in the extremities and to the adjacent spinous process or body(caudal) in spine, followed by registration of anatomy. A tool navigator was utilized to plan the key hole incision so that the trajectory did not involve important anatomical structure. A sleeve was then introduced which allowed the usage of instruments like a burr and curette to deroof the nidus, curette the nidus and obtain material for histopathology and further burr the cavity to ensure complete eradication of the nidus. During the entire procedure, the tool navigator was used frequently to reconfirm the location and the depth of burring. Following excision, registration using Iso-C 3D C-arm was done to confirm the complete eradication of the nidus. The age of the patients varied from 10 years to 27 years. In the extremities, location of the MIRA was in the same bone and firm anchorage was obtained using either a single Steinman pin locator (4 patients) or a double pin locator (1 patient). In spine the MIRA was attached to the adjacent spinous process (caudal) in the cervical, thoracic or lumbar region (5 patients) and in sacrum (1 patient) it was attached using a Steinman pin to the adjacent vertebral body. Excellent three-dimensional view of the nidus and localization was possible in all patients. A safe trajectory that avoided anatomical structures was possible in all patients using a tool navigator. The incision ranged from 1 to 4 cms. Adequate material for histology was obtained in ten patients that confirmed the diagnosis of osteoid osteoma and in one patient histopathological confirmation was not possible because the nidus was completely destroyed during the process of deroofing and burring. In ten patients, post excision ISO-C 3D scans confirmed adequate removal and in one patient, it was successful in identifying incomplete removal requiring further excision of the nidus. The average operating time was 62 mins (37–90 mins) and the blood loss was less than 30 cc in all patients. All patients achieved excellent pain relief and were asymptomatic at an average follow up of 3.4 (2.2 – 3.9) years. Iso-C 3 D navigation offers the advantage of excellent localization of the nidus and percutaneous excision of these tumors, thereby conserving bone in critical locations like the spine and upper end of femur. It also offers the advantage of intraoperative confirmation of adequate excision and allows harvesting the nidus for histological confirmation

Introduction: Failures of treatment of osteoid osteoma (OO) are related to errors in exact localization and incomplete excision of the nidus. Intraoperative Iso-C 3D navigation allows exact localization, excision and confirmation of excision by percutaneous Methods:. Methods: We report the successful percutaneous excision of OO in 11 patients (extremities-5; spine-6). All patients had a minimally invasive reflective array (MIRA) fixed to the same bone in the extremities and to the adjacent spinous process or body(caudal) in spine, followed by registration of anatomy. A tool navigator was utilized to plan the key hole incision so that the trajectory did not involve important anatomical structure. A sleeve was then introduced which allowed the usage of instruments like a burr and curette to deroof the nidus, curette the nidus and obtain material for histopathology and further burr the cavity to ensure complete eradication of the nidus. Following excision, registration using Iso-C 3D C-arm was done to confirm the complete eradication of the nidus. Results: The age of the patients varied from 10 to 27. In the extremities, location of the MIRA was in the same bone and firm anchorage was obtained using either a single Steinman pin locator (4 patients) or a double pin locator (1 patient). In spine the MIRA was attached to the adjacent spinous process (caudal) in the cervical, thoracic or lumbar region (5 patients) and in sacrum (1 patient) it is attached using a Steinman pin to the adjacent vertebral body. Excellent three-dimensional view of the nidus and localization was possible in all patients. A safe trajectory that avoided anatomical structures was possible in all patients using a tool navigator. The incision ranged from 1 to 4 cms. Adequate material for histology was obtained in ten patients that confirmed the diagnosis of osteoid osteoma and in one patient histopathological confirmation was not possible because the nidus was completely destroyed during the process of deroofing and burring. In ten patients, post excision ISO-C 3D scans confirmed adequate removal and in one patient, it was successful in identifying incomplete removal requiring further excision of the nidus. The average operating time was 62 mins (37–90 mins) and the blood loss was less than 30 cc in all patients. All patients achieved excellent pain relief and were asymptomatic at an average follow up of 3.4 (2.2 – 3.9) years. Conclusions: Iso-C 3 D navigation offers the advantage of excellent localization of the nidus and percutaneous excision of these tumors, thereby conserving bone in critical locations like the spine and upper end of femur. It also offers the advantage of intraoperative confirmation of adequate excision and allows harvesting the nidus for histological confirmation

Objective. To evaluate the rise in impedance during percutaneous radiofrequency thermo coagulation (PRFTC) of osteoid osteomas as a predictor of local recurrence. Design and Patients. A prospective study of 23 patients (24 PRFTC procedures) with minimum of 2.25-year follow-up (average 3.3 years). Average age 19.6 years (range 4–44), sex ratio 15□:□8 (male□:□female), 16 non-diaphyseal, 7 diaphyseal. Results. In 19 procedures, an increase in impedance was measured—no recurrences have occurred in this group to date. In 5 procedures, no increase in impedance was seen (3 non-diaphyseal, 2 diaphyseal), and 1 recurrence has been seen in this group to date. This difference is statistically significant with a P value of .05