Unexplained "massive osteolysis of femoral head" (MOFH) after acetabular fracture: occurrence and suggested patho-etiology.

Background We observed cases of extensive osteolysis of the femoral head following acetabular fractures even though the original fracture did not involve the femoral head or neck. This observation has been called massive osteolysis of the femoral head (MOFH). Purpose To evaluate the clinical and imaging features of MOFH to gain a better understanding of its patho-etiology. Material and Methods We retrospectively collected cases of acetabular fractures seen over a period of 10 years and evaluated the clinical features and imaging characteristics. The findings were compared with the features of other complications such as osteonecrosis, rapidly progressive osteoarthritis, or post-traumatic osteolysis. Results Fifteen patients (M:F ratio 9:6; mean age, 61.6 years) out of 244 had MOFH (prevalence: 6.1%). Motor vehicle collision and falls were the most common mechanisms of injury. The time interval for developing MOFH was in the range of 1-18 months after the initial injury. Patterns of femoral head osteolysis varied from eccentric (12 cases) to transcervical (3 cases). Four cases of eccentric osteolysis developed high-degree of osteolysis. MOFH was observed near the surgical hardware in 6/15 cases. One biopsy specimen did not reveal typical features of osteoarthritis or avascular necrosis. Conclusion MOFH appears to be a distinct entity from avascular necrosis or rapidly progressive osteoarthritis. It is suggested that MOFH is a variant of post-traumatic osteolysis that is evident in a subset of patients.

Patients with rheumatoid arthritis in clinical remission manifest persistent joint inflammation on histology and imaging studies.

OBJECTIVE: The purpose of our study was to test the hypothesis that synovitis on magnetic resonance imaging (MRI) and ultrasound (US) observed in patients with rheumatoid arthritis (RA) who meet remission criteria reflects active inflammation on histopathology. METHODS: We analyzed 15 synovial specimens obtained during surgical procedures from 14 patients with RA in clinical remission as defined by the American College of Rheumatology criteria. Histological specimens were scored for hyperplasia of synovial lining and synovial stroma, inflammation, lymphoid follicles, and vascularity. The histology scores were classified as minimal, mild, moderate, or severe disease activity. US and MRI performed within a 4-month period of surgery were scored for disease activity. The correlation between histology and imaging scores was examined. RESULTS: Four of 14 patients were receiving anti-tumor necrosis factor (TNF) therapy, 4 were receiving methotrexate (MTX) alone, 4 were taking MTX and hydroxychloroquine (HCQ), and 1 was taking HCQ and sulfasalazine. Four specimens had severe, 6 moderate, 3 mild, and 2 minimal disease activity on histology. Three of 4 specimens with minimal and mild histology were observed in subjects receiving anti-TNF therapy. Synovitis was noted on greyscale in 80% of joints and Doppler signal in 60%. MRI demonstrated synovitis and bone marrow edema in 86% of images. Positive but not significant correlations were noted between histology and synovitis scores on US. CONCLUSION: Despite clinical remission, histology and imaging studies documented a persistently active disease state that may explain the mechanism for radiographic progression.

Cruciate ligament integrity in osteoarthritis of the knee.

OBJECTIVE: To evaluate, using magnetic resonance imaging (MRI), the prevalence of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) rupture in knees with symptomatic osteoarthritis (OA) compared with those without OA, and the relationship to pain and recalled injury. METHODS: MRI and plain radiography of the knee were performed in a group of 360 subjects with painful knee OA (cases; 66.7% male, mean age 67.1 years) and 73 without knee pain (controls; 57.5% male, mean age 66.1 years). MRIs were read for the presence or absence of complete or partial ACL or PCL tear. Subjects with knee pain were asked to quantify severity of pain on a visual analog scale and to report whether they could recall a significant knee injury (requiring use of a cane or crutches). We compared the prevalence of ACL and PCL rupture in those with and those without knee pain and also evaluated whether, in cases, there was any association with recalled knee injury. RESULTS: The proportion of cases who had complete ACL rupture was 22.8%, compared with 2.7% of controls (P = 0.0004). PCL rupture was rare both in cases (0.6%) and in controls (0%). Cases with ACL rupture had more severe radiologic OA (P < 0.0001) and were more likely to have medial joint space narrowing (P < 0.0001) than cases with intact ACLs, but did not have higher pain scores. Among cases, only 47.9% of those with complete ACL tears reported a previous knee injury, compared with 25.9% of those without complete ACL tears (P = 0.003). CONCLUSION: ACL rupture is more common among those with symptomatic knee OA compared with those without knee OA. Fewer than half of subjects with ACL rupture recall a knee injury, suggesting that this risk factor for knee OA is underrecognized.

Collar osteophytes: a cause of false-positive findings in bone scans for hip fractures.

OBJECTIVE: A retrospective review of our radiology database revealed five elderly patients, seen over a 12-month period, whose findings were judged positive for hip fractures on the basis of their bone scans, but whose MR imaging findings were negative. CONCLUSION: The presence of collar osteophytes around the femoral neck caused a false diagnosis of hip fracture for these patients, as revealed on radionuclide bone scans. CT or MR imaging correlation is needed where collar osteophytes may have caused an incorrect diagnosis of hip fracture based on a bone scan.

Volumetric computerized tomography as a measurement of periprosthetic acetabular osteolysis and its correlation with wear.

Osteolysis, which is considered to be a major source of morbidity following total hip joint replacement, has been notoriously difficult to measure accurately, particularly in the acetabular area. In order to study periacetabular osteolysis, specialized software for computerized tomography (CT) scan image analysis has been developed. This software (3D-CT) eliminates metal artifacts, allows three-dimensional segmentation of the CT image, and reconstructs the segmented image to provide an accurate representation and measurement of volume for osteolytic lesions. In the present study, 20 patients underwent periacetabular osteolytic volume determination using 3D-CT, functional assessment (using the Harris Hip Scale, the Western Ontario and McMaster University Osteoarthritis Index, and the short form 36 questionnaire), and two-dimensional analysis of volumetic polyethylene wear using digitalized plain films. Periacetabular osteolysis correlated directly with the polyethylene wear rate (relative risk [RR] = 0.494, P = 0.027). If one patient with an acetabular revision, one patient with recurrent dislocation, and one patient with a Biomet prosthesis are excluded, then the correlation between wear and osteolysis is improved (RR = 0.685, P = 0.002). In summary, the current study demonstrates both the feasibility of CT imaging of periacetabular osteolysis and the correlation between polyethylene wear and osteolytic volume, providing a potential outcome measure for clinical trials that are designed to examine interventions in this complex disease process.