23 Synovial Proliferative Disorders
Intra-articular cartilaginous bodies that break off into individual nodules that can calcify.
The hip is the second most commonly affected joint (knee is first).
Usually occurs between age 30 and 50 years.
History: Most often patients will complain of groin and buttocks pain, which is worsened with activity. They can also complain of mechanical symptoms, including stiffness, grinding, and catching with motion. Most commonly presents as pain, limited motion, and mechanical symptoms.
Physical examination: Provocative hip maneuvers such FABER (flexion, abduction, and external rotation) or flexion, adduction, and internal rotation (FADIR) will often illicit pain. Patients may also present with restricted motion in the hip, especially internal rotation.
Radiographs: Loose bodies visible if calcified. In late stages, concurrent signs of osteoarthritis are evident, that is, joint space narrowing, subchondral sclerosis, and osteophyte formation 3 , 4 ( Fig. 23.1 ).
Computed tomography (CT): Osteochondral bodies may or may not be visible.
MRI: Noncalcified loose bodies are low signal T1 and high signal T2. Calcified bodies are low signal on T1 and T2 ( Fig. 23.2 ).
Little role for histology; findings include cartilaginous nodules in various stages of calcification.
Arthroscopic debridement has been described with the goal of less morbidity and faster recovery. Potential disadvantages include incomplete synovectomy and inadequate visualization of loose bodies. It also requires advanced proficiency in hip arthroscopy, which may not be readily available.
i. A recent meta-analysis of 197 patients demonstrated a recurrence rate of 7.1% at last follow-up. Conversion to THA at follow-up was most strongly predicted by the presence of full-thickness cartilage defects at arthroscopy. 1 , 2 , 4
Open debridement and synovectomy without femoral head dislocation has a greater recurrence rate than synovectomy with femoral head dislocation.
A modified Hardinge approach with care to avoid the posterior capsule has been described to avoid compromising vascularity to the femoral head.
Open synovectomy with femoral head dislocation demonstrated no recurrence in one series but resulted in a greater than 20% complication rate including avascular necrosis of the femoral head, nerve palsy, and intraoperative femur fracture. A trochanteric osteotomy may be utilized to facilitate dislocation. 5
Risk of progression of degenerative joint disease exists after synovectomy.
Greater severity of preoperative degenerative disease joint predicts progression of osteoarthritis.
Hip arthroplasty with synovectomy is indicated for those with severe degenerative joint disease and concomitant chondromatosis. 5
Pigmented Villonodular Synovitis
Villous proliferation of synovium with hemosiderin deposition.
Presents as isolated area of hypertrophic synovium or diffuse disease.
Hip the second most commonly affected joint (after knee). 9
Usually monoarticular but can present as polyarticular disease.
Affects both genders equally, usually in third or fourth decades of life. 10
History: Isolated patches of PVNS in the hip will be described at discrete mechanical symptoms with catching or locking sensations during hip motion. Diffuse disease may also present with mechanical symptoms but can also be described as dull and diffuse groin and buttocks pain, which is worsened with activity.
Physical examination: Hip motion will often be restricted with positive provocative hip maneuvers. Stinchfield’s (resisted hip flexion) and FADIR tests will often illicit pain in the groin. Patients may also present with a fixed hip flexion contracture in diffuse disease.
Aspiration may contain hemosiderin-laden fluid and giant cells, but may be normal. 10
Plain films often normal, though hip PVNS often presents with concomitant arthritis.
CT scan: PVNS appears as mass that is higher density than skeletal muscle. 9
Definitive diagnosis is by biopsy: percutaneous, arthroscopic, or open.
Pathology: Mononuclear stromal cells infiltrating synovium with hemosiderin laden multinucleated giant cells. 9
Minimal role for symptomatic patients.
Cortisone injections can provide transient relief but are not curative.
Diffuse PVNS requires complete synovectomy with or without arthroplasty.
Extent of degenerative joint disease is associated with higher risk of recurrence.
Arthroplasty allows for dislocation of femoral head and more complete synovectomy:
i. In several series reporting on hip arthroplasty, there were no recurrences reported of PVNS after hip arthroplasty. However, aseptic loosening has been reported as a complication with cemented THA.
ii. A more recent series employing cementless prosthesis demonstrated successful outcomes with revisions only required for polyethylene wear. 13
Adjuvant therapy with radiation or radioactive isotopes may be effective 14 :
May be used as an adjunct following surgical resection.
Can also be used for recurrent disease instead of surgery.
Series have demonstrated low recurrence rates when low-dose radiation has been applied after radiation 15 :
i. Low-dose radiation can be initiated 6 weeks after surgery.
ii. Radiation carries risk of skin breakdown, joint stiffness, and theoretical risk of malignancy.
Intra-articular radioactive isotopes can also be used to control diffuse disease and prevent recurrence 16 :
i. Yttrium-90 (Y-90) and dysprosium-165 (Dy-165) also have been used as adjuvant therapies.
ii. A series of patients who failed previous synovectomy and underwent repeat synovectomy with intra-articular radioactive isotopes demonstrated an 18% recurrence rate.
Synovial sarcoma or synovial hemangioma may present with similar presentation and imaging.
Recurrence after resection is common and routine postoperative MRI monitoring may assist in detecting early recurrence.