Table 2.
Pretibial cyst case series
| Patient number | Age (years) | Concurrent pathology at the time of initial surgery and management | Prior treatment before excision | Concurrent pathology at time of cyst removal | ACL intact in notch and tibial tunnel? | MRI | Pathology | Cultures | Followup |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 48 | None | Observation | None | Y | Multiloculated cyst tracking from the tibial screw into the pretibial soft tissues | Multiloculated cyst set in aponeurotic tissue and adipose tissue with strongly birefringent PLLA material; cystic cavities borne out of degenerated, lyzed collagen in the midst of particles of PLLA; many foci of collagen degeneration attended by foamy histiocytes | Y | 5 months |
| 2 | 48 | Lateral meniscus tear—débrided; medial meniscus tear—repaired | Observation | Lateral meniscus tear; LFC/patellar chondromalacia | Y | Osteolysis surrounding the tibial screw; edema surrounding screw | Cystic cavities of degenerated, lyzed collage with particles of PLLA; foci of collagen degeneration attended by foamy histiocytes | Y | 5 months |
| 3 | 57 | None | Observation | None | Y | Fluid tracking down the tibial tunnel | Fibrous and fibroadipose tissue; lymphocytic palisading; inflammation around cystic space; foreign body giant cell reaction around refractile, nonbirefringent and rare birefringent material and focal acute inflammation within the fibrotic wall | Y | 5 months |
| 4 | 22 | None | Aspiration and antibiotics | None | Y | Large joint effusion with fluid tracking down the tibial tunnel and extending into the soft tissues anterior to the tibia | Foreign body reaction around birefringent material; focal acute inflammation within the fibrotic wall | Y | 6 months |
| 5 | 26 | None | Antibiotics and observation | None | Y | Fluid tracking down the tibial tunnel | Birefringent foreign material in bone; granulation tissue, necrosis, acute and chronic inflammatory infiltration and fibrosis | Y | 6 months |
| 6 | 51 | Lateral meniscus tear—débrided | Observation | Lateral meniscus tear; Baker’s cyst | Y | Bone marrow edema; transcortical tibial cystic lesion | Focal perivascular small lymphoid aggregates; fibrohistiocytic palisading pseudogranulomatous inflammation around necrotic tissue and debris; small birefringent particles; no acute inflammation (ie, infection) | Y | 5 months |
| 7 | 23 | None | Observation | None | Y | Anteromedial cyst communicating with joint | Foreign body reaction around birefringent material and focal acute inflammation | Y | 5 months |
LFC = lateral femoral condyle; Y = yes; PLLA = L-poly-L-lactide.