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

Aims

The number of patients undergoing arthroscopic surgery of the hip has increased significantly during the past decade. It has now become an established technique for the treatment of many intra- and extra-articular conditions affecting the hip. However, it has a steep learning curve and is not without the risk of complications. The purpose of this systematic review was to determine the prevalence of complications during and following this procedure.

Aims

Femoral impaction bone grafting was first developed in 1987 using morselised cancellous bone graft impacted into the femoral canal in combination with a cemented, tapered, polished stem. We describe the evolution of this technique and instrumentation since that time.

Four uncemented Symax hip stems were extracted at three weeks and nine, 13 and 32 months, respectively, for reasons other than loosening. The reasons for implant removal were infection in two cases, recurrent dislocation in one and acetabular fracture in one. They were analysed to assess the effect and behaviour of an electrochemically deposited, completely resorbable biomimetic BONIT-hydroxyapatite (HA) coating (proximal part) and a DOTIZE surface treatment (distal part) using qualitative histology, quantitative histomorphometry and scanning electron microscopy (SEM). Early and direct bone-implant bonding with signs of active remodelling of bone and the HA coating were demonstrated by histology and SEM. No loose BONIT-HA particles or delamination of the coating were observed, and there was no inflammation or fibrous interposition at the interface.

Histomorphometry showed bone-implant contact varying between 26.5% at three weeks and 83.5% at 13 months at the HA-coated implant surface. The bone density in the area of investigation was between 24.6% at three weeks and 41.1% at 32 months. The DOTIZE surface treatment of the distal part of the stem completely prevented tissue and bone apposition in all cases, thereby optimising proximal stress transfer.

The overall features of this implant, in terms of geometry and surface texture, suggest a mechanically stable design with a highly active biomimetic coating, resulting in rapid and extensive osseo-integration, exclusively in the metaphyseal part of the stem. Early remodelling of the HA coating does not seem to have a detrimental effect on short-term bone-implant coupling. There were no adverse effects identified from either the BONIT-HA coating or the DOTIZE surface treatment.