Dorsal defect of the patella: MR features

Dorsal defect of the patella (DDP) is a benign lesion with characteristic radiologic features. We describe the MR appearance of a typical DDP and a healed DDP as seen in two patients. The classic CT appearance is also described.     

Dorsal defect on a multi-partite patella: imaging findings

Coincidence of dorsal defect on a multipartite patella constitutes a rare cause of anterior knee pain in the first decades of life. Imaging findings of this uncommon symptomatic skeletal variant are discussed, with emphasis on MR features.     

Dorsal defect of the patella: concept of its origin and relationship with bipartite and multipartite patella

In a series of 2286 single radiographic examinations of the knee in 1985, 6 dorsal defects of the patella (DDP) were detected. The diagnosis was made if a round lucent lesion of the dorsal superolateral surface of the patella [9] was found abutting against articular cartilage [10]. In four of our patients, an association with a multipartite patella (MP) was found. Biopsy of one lesion showed dense connective tissue and areas of bone necrosis. In one patient, the pattern of reossification of the lesion could be demonstrated. Our observations provide further evidence that the DDP is a stressinduced anomaly of ossification rather than a posttraumatic subarticular cyst of the patella, a diagnosis sometimes suggested by the clinical context. The initial lesion is probably a traction lesion at the insertion of the vastus lateralis muscle rather than ulceration of articular cartilage. We suggest a possible relationship between dysfunction of the quadriceps mechanism, patellar subluxation, and the genesis of the DDP.     

Dorsal effect of the patella: incidence and distribution

To determine the incidence and distribution of dorsal defect of the patella, the radiographs of 2,349 knees in 1,192 consecutive patients were evaluated. The defect was present in about 1% of the population. It may be found at any age from the preadolescent to the mature adult. Females were more commonly affected than males. The test population group was validated by concurrent tabulation and comparison with other series of two other bening lesions occurring at the knee: fabella and multipartite patella.     

Dorsal fracture of the hamate: distinctive radiographic appearance

Six patients who injured their wrists had radiographs documenting a dorsal, 5- to 10-mm oblong fragment of bone immediately proximal to the base of the fourth and/or fifth metacarpal bones. The fragment was seen on the pronation oblique and/or lateral projections, but not on the posteroanterior projection. The radiographic appearance of the fragment was remarkably similar in all cases. In the one patient in which it was performed, pluridirectional tomography demonstrated that the fragment originated from the dorsal surface of the hamate. Five of the six patients also had associated posterior dislocation of the fourth and/or fifth metacarpals. We conclude that this fragment represents a coronal fracture through the body of the hamate resulting from posterior dislocation or subluxation of the fourth and/or fifth metacarpal.     

Symptomatic dorsal defect of the patella in a runner

The dorsal defect of the patella is a benign lesion characteristically located in the superolateral corner of the patella. The microscopic pathology shows fibrous tissue, reactive woven bone, and stringy, eosinophilic, extracellular debris. Although the lesion is usually asymptomatic, the juxtaarticular location in the patella can provoke symptoms in the athlete. Excision of the lesion and cancellous bone graft of the defect resolved the problem in a competitive adolescent runner.     

Calcified bodies in popliteal cysts: a characteristic radiographic appearance.

Calcified bodies in popliteal cysts have a characteristic radiographic appearance which can be confirmed by arthrography. Calcified bodies may arise in the true joint due to trauma, arthropathy resulting in joint destruction, or synovial osteochondromatosis. These calcified loose bodies may pass into a popliteal cyst through posterior joint-bursal communications or can arise in a popliteal cyst by chondrometaplasia. Correct radiographic interpretation will exclude soft tissue tumors and vascular lesions as differential considerations. Management of these patients will be determined by the clinical circumstances since neither popliteal cysts nor synovial osteochondromatosis are necessarily symptomatic.     

The vertical position of the patella estimated by four radiographic measurements

The methods of Insall and Salvati, Blackburne and Peel, Caton and Laurin of assessing the vertical position of the patella, were applied on 200 normal knees. The indices for Insall and Salvati's, and Blackburne and Peel's methods were 1.07 +/- 0.25 and 0.78 +/- 0.19 respectively, independent of sex and flexion of the knee. The measurements for Caton's index were 0.95 +/- 0.24 and 0.88 +/- 0.22 at kneeflexions of 45 degrees and 90 degrees. Laurin's method was insufficient as it showed 50% of the patellas to be high riding. The different methods were compared. The technique of Insall and Salvati was a reliable and applicable method, and is therefore recommended for routine use.     

Medial patellar ossification after patellar instability: a radiographic finding indicative of prior patella subluxation/dislocation

Objective  To describe the correlation between medial patellar ossification and prior patella subluxation and/or dislocation. Materials and methods  A retrospective billing database search identified 544 patients who had been diagnosed with patellar instability over a 13-year period. One hundred twenty-eight patients met the inclusion criteria. After review by a staff orthopedic surgeon and two musculoskeletal radiologists, 28 patients were found to have medial patellar ossification. The size and location of medial patellar ossification was recorded. Results  Of the 28 patients (20 males, eight females, age 13–66 years, mean 28 years) who were found to have medial patellar ossification, 22 had radiographs, 16 had magnetic resonance imaging, and ten had both. The medial patellar ossification ranged in size from 2 to 18 mm with an average of 6.8 mm. Twelve were located in the medial patellofemoral ligament (MPFL), 14 in the medial joint capsule, and two in both the MPFL and joint capsule. Twenty-seven of 28 patients had a single ossification, and one patient had two ossifications. The timing from injury to first imaging of the lesion ranged from 10 days to a chronic history (≥35 years) of patellar instability. Conclusion  Medial patellar ossification correlates with a history of prior patella subluxation and/or dislocation. The medial ossification can be seen within the MPFL or the medial joint capsule, suggesting remote injury to these structures. The presence of this lesion will prompt physicians to evaluate for patellar instability.     

Therapeutic neuromuscular paralysis in neonates: characteristic radiographic features

Neonates with respiratory distress requiring mechanical ventilation may be treated with muscular paralysis to improve oxygenation. This results in characteristic radiographic features that relate in part to the specific drug used. The radiographic signs are: bell-shaped chest, decreased bowel gas, and soft-tissue edema. When all three findings are present, the use of neuromuscular blockade can be suggested from the radiographs alone without the aid of clinical history. Radiographs of 57 infants treated with muscular paralysis and mechanical ventilation were compared to 20 infants treated with mechanical ventilation alone. In paralyzed patients, a characteristic bell-shaped chest was seen in 24 of 57 and decreased bowel gas in 46 of 52. Soft-tissue edema was seen in patients treated with metocurine, and the incidence increased with duration of therapy (18 of 25 treated for 5 or more days); it was not radiographically detected in patients treated with d-tubocurarine (0 of 13). Bell-shaped chest, decreased bowel gas, and soft-tissue edema occurred one, three, and one times, respectively, in 20 nonparalyzed control infants, and each time the findings carried significantly different clinical implications. All cases were reviewed to determine if pulmonary edema can result from mobilization of soft-tissue edema fluid after cessation of neuromuscular paralysis, and this was found not to occur.     

髌骨囊性骨结核1例

患者男性，17岁。无诱因出现左膝关节疼痛6个月余，呈持续性酸痛，活动时加重，休息时缓解，当地医院按“滑膜炎”对症治疗无效。于1999年4月28日入院，无低热、盗汗及结核病史。查体：一般情况良好，左膝关节皮肤色泽、皮温正常，关节周围软组织稍肿胀，屈曲活动受限，实验室检查无异常发现。X线胸片正常，髌骨侧位示髌骨外上方呈类圆     

A case of painful defect of unknown origin of the pediatric patella

An uncertain history of potential trauma versus possible developmental variants and disorders in childhood may cause differential diagnostic problems in pediatric radiology. We report the case of a 12-year old boy with an unclear unilateral defect of the patella and long-persisting complaints in his knee. The plain radiological and MRI morphology of this lesion are described and possible differential diagnoses are discussed.     

Atrial septal defect in older adults: atypical radiographic appearances

Atrial septal defect (ASD) is the most common congenital cardiac anomaly manifested in adulthood. Clinical and radiographic features are well defined in patients less than 30 years of age. In older patients, however, the clinical symptoms are often atypical, and the auscultatory findings may be misleading. The radiographic manifestations in older patients have not been well described. In the current study, of 70 patients over the age of 50 years with proved ASD, 21 (30%) had atypical radiographic features, including apparently normal vascularity, left atrial enlargement, pulmonary venous hypertension, and pulmonary edema. In a control group of 70 younger patients with ASD, only 5.7% had atypical findings. The development of pulmonary venous hypertension and pulmonary edema in older patients was associated with smaller defects and a higher prevalence of mitral valve disease, left ventricular dysfunction, and pulmonary arterial hypertension than seen in older patients with typical radiographic findings.