[Reactive synovitis: MRI features with arthroscopic correlation]

Will rheumatologists ever pick up the arthroscope again?

Conditions prompting physicians and surgeons first adapting endoscopes to peer into joints were mainly the sort of synovial conditions that would concern today's rheumatologists. Rheumatologists were among the pre-World War II pioneers developing and documenting arthroscopy. The post-War father of modern arthroscopy, Watanabe, found rheumatologists among his early students, who took back the technique to their home countries, teaching orthopedists and rheumatologists alike. Rheumatologists described and analyzed the intra-articular features of their common diseases in the '60s and '70s. A groundswell of interest from academic rheumatologists in adapting arthroscopy grew considerably in the '90s with development of "needle scopes" that could be used in an office setting. Rheumatologists helped conduct the very trials the findings of which reduced demand for their arthroscopic services by questioning the efficacy of arthroscopic debridement in osteoarthritis (OA) and also developing biological compounds that greatly reduced the call for any resective intervention in inflammatory arthropathies. The arthroscope has proven an excellent tool for viewing and sampling synovium and continues to serve this purpose at several international research centers. While cartilage is now imaged mainly by magnetic resonance imaging, some OA features - such as a high prevalence of visible calcinosis - beg further arthroscopy-directed investigation. A new generation of "needle scopes" with far superior optics awaits future investigators, should they develop interest.

Tumours and tumour-like lesions of joints: Differential diagnoses in a paediatric population compared to adults

OBJECTIVE

To determine the differential diagnosis of intra-articular tumours and tumour-like lesions in a paediatric population compared to adults.

METHODS

Retrospective review of children up to the age of 18 years with suspected intra-articular tumours and tumour-like lesions referred to a specialist musculoskeletal oncology service from January 2019 to August 2020. Data recorded included patient age and gender, lesion location and morphology (based on the classification system of Adams et al.), and the final diagnosis made either by image-guided biopsy/resection or by clinical and imaging features. Comparison was then made with a group of adults presenting during the same period.

RESULTS

28 paediatric patients were included (12 males and 16 females with mean age 11.2 years, range 3-18 years). Joints involved were the knee (n = 22; 78.6%), ankle (n = 4; 14.3%), hip (n = 1; 3.6%) and elbow (n = 1; 3.6%). Lesion morphology was Type 1 (n = 18; 64.3%), Type 2 (n = 3; 10.7%), Type 3 (n = 1; 3.6%) and Type 4 (n = 5; 17.9%). Final diagnosis was made by image-guided biopsy/resection in 18 (64.3%) patients. The commonest neoplastic lesion was tenosynovial giant cell tumour (n = 11; 39.3%), followed by synovial haemangioma (n = 5; 17.9%). There was only a single malignant lesion, a case of synovial sarcoma. Of eight (28.6%) non-neoplastic lesions, three were diagnosed as juvenile idiopathic arthritis and three as non-specific synovitis. There was no difference compared to adults regarding gender, joint involved or lesion morphology, but there was a significant difference in final diagnoses (p < 0.001). The range of intra-articular tumours and tumour-like lesions in children differs from that in adults, although tenosynovial giant cell tumour is the commonest diagnosis in both groups and malignant lesions are rare.

ADVANCES IN KNOWLEDGEART

In our series, ~16% of tumours and tumour-like lesions of joints occur in the paediatric population. Tenosynovial giant cell tumour remains the commonest diagnosis in children as in adults. Synovial haemangioma and juvenile idiopathic arthritis were the next commonest diagnoses in children, while primary synovial chondromatosis and reactive synovitis were the next commonest diagnoses in adults. Malignant lesions are rare in both groups.

Suspected intra-articular soft-tissue tumours and tumour-like lesions: Performance of image-guided core needle biopsy

PURPOSE

To determine the efficacy of image-guided core needle biopsy (IGCNB) in patients presenting with suspected intra-articular soft tissue tumours or tumour-like lesions.

METHODS

Retrospective study of patients referred to a musculoskeletal oncology service between January 2019 and May 2020 with a suspected intra-articular soft tissue tumour over a 16-month period. Data collected included patient age, gender, joint involved and maximal lesion size. Type of image-guidance (ultrasound or computed tomography), type of needle and type of anaesthesia, general anaesthetic (GA) or local anaesthetic (LA), were recorded, as was the histological diagnosis. For patients who proceeded to surgical excision, the IGCNB histology result was correlated with resection histology. Descriptive statistics were used and complications were also noted.

RESULTS

By the termination of data collection 91 patients underwent IGCNB, 32 (35.2 %) males and 59 (64.8 %) females with a mean age of 41.4 years (age range 3-86 years). The joints involved were the knee (n = 73; 80.2 %), ankle (n = 12; 13.2 %), hip (n = 3; 3.3 %), shoulder (n = 1; 1.1 %), elbow (n = 1; 1.1 %) and wrist (n = 1; 1.1 %). Biopsy types were as follows: US-guided GA (n = 29; 31.9 %), US-guided LA (n = 37; 40.7 %), CT-guided GA, (n = 23; 25.3 %), CT-guided LA (n = 2; 2.2 %). Mean maximal tumour dimension for 76 focal lesions was 36.5 mm (range 18-113 mm). IGCNB yielded a definitive histological result in 85 of 91 cases (93.4 %), 44 of whom went on to surgical resection. Concordance between IGCNB and resection histology was achieved in 42 of 44 cases (95.5 %). The commonest diagnosis was tenosynovial giant cell tumour, with only a single malignant lesion identified. There were no recorded immediate or delayed complications.

CONCLUSIONS

IGCNB of suspected intra-articular tumours or tumour-like lesions is a highly effective and safe technique.

Synovial inflammation plays a greater role in post-traumatic osteoarthritis compared to idiopathic osteoarthritis in the Hartley guinea pig knee

Background

The objective of this study was to evaluate the extent of stromal cell-derived factor-1’s (SDF-1) involvement in the pathogenesis of idiopathic versus post-traumatic OA by comparing differences in synovial membrane morphology, SDF-1 synovial fluid (SF) concentrations, and matrix metalloproteinase-13 (MMP-13) SF concentrations.

Methods

Thirty-six 3-month-old Hartley guinea pigs were obtained and divided into 6 groups. Upon sacrifice, India Ink staining was used to evaluate gross morphology, Safranin O/Fast green staining was used to assess cartilage damage, H/E staining was employed to visualize the synovium, and SF samples were obtained for biochemical analyses. Sandwich ELISA was used to quantify the SF concentrations of SDF-1 and MMP-13.

Results

12 month-old, idiopathic OA guinea pigs and 5.5 month-old ACLT animals had comparable cartilage damage when evaluated by the Modified Mankin Score. SDF-1 and MMP-13 concentrations were not statistically different between the two groups. The synovial membrane of the 5.5 month ACLT group had severe synovitis compared to the idiopathic OA group.

Conclusion

In this study, it was found that synovial inflammation, independent of cartilage morphology, SDF-1 concentration, and MMP-13 concentration, was markedly different between idiopathic and post-traumatic OA. These results highlight the differing morphological and biochemical profiles of post-traumatic versus idiopathic osteoarthritis and calls for a more thorough examination of the sole of the synovial membrane in the pathogenesis of post-traumatic osteoarthritis.

Early reactive synovitis and osteolysis after total hip arthroplasty

BACKGROUND

Little is known about intraarticular pathology following THA prior to the radiographic appearance of osteolysis, primarily due to imaging limitations. MRI has recently been applied to imaging the postarthroplasty hip with the ability to detect periarticular bony and soft tissue pathology; specifically, it is able to detect abnormal synovial patterns and focal bone loss well before the radiographic appearance of osteolysis.

QUESTIONS/PURPOSES

We therefore used MRI to determine the incidence of early reactive synovitis and osteolysis in asymptomatic patients after THA, and whether there is an association between these MRI findings and clinical outcomes or radiographic wear measurements at this early stage.

METHODS

We recruited 31 patients (33 hips) who underwent routine noncemented THA with one of three types of bearing surfaces: metal-on-cross-linked polyethylene (n = 7), ceramic-on-ceramic (n = 12), and ceramic-on-cross-linked polyethylene (n = 14). Patients underwent specialized MRI at a minimum of 12 months (mean, 23 months; range, 12-37 months) after surgery. MR images were analyzed for the presence of synovitis or osteolysis. WOMAC scores, patient assessment questionnaires, and radiographic wear measurements were correlated with MRI findings.

RESULTS

Reactive synovitis was observed in 13 of 33 patients (39%) and focal osteolysis in one of 33 (3%). The presence of synovitis did not correlate with pain, activity level, patient satisfaction or clinical outcome scales, nor did it correlate with radiographic wear measurements at early followup.

CONCLUSIONS

Our observations suggest reactive synovitis is common yet asymptomatic at short-term followup. We do not know either the etiology or the long-term implications of these observations.

[Isolated synovial chondromatosis of the subacromial bursa: report of a new case and review of the literature]

Synovial chondromatosis is a rare metaplasia of the synovium of unknown etiology that may involve occasionally the subacromial bursa. We report a new case diagnosed by ultrasound in a 30-year-old man and we present pathogenetic, diagnostic and therapeutic features of this disease with a literature review.