Aims

The purpose of this retrospective study was to differentiate between the MRI features of normal post-operative change and those of residual or recurrent disease after intralesional treatment of an atypical cartilage tumour (ACT)/grade I chondrosarcoma.

Giant cell tumours (GCT) of the synovium and tendon sheath can be classified into two forms: localised (giant cell tumour of the tendon sheath, or nodular tenosynovitis) and diffuse (diffuse-type giant cell tumour or pigmented villonodular synovitis). The former principally affects the small joints. It presents as a solitary slow-growing tumour with a characteristic appearance on MRI and is treated by surgical excision. There is a significant risk of multiple recurrences with aggressive diffuse disease. A multidisciplinary approach with dedicated MRI, histological assessment and planned surgery with either adjuvant radiotherapy or systemic targeted therapy is required to improve outcomes in recurrent and refractory diffuse-type GCT.

Although arthroscopic synovectomy through several portals has been advocated as an alternative to arthrotomy, there is a significant risk of inadequate excision and recurrence, particularly in the posterior compartment of the knee. For local disease partial arthroscopic synovectomy may be sufficient, at the risk of recurrence. For both local and diffuse intra-articular disease open surgery is advised for recurrent disease. Marginal excision with focal disease will suffice, not dissimilar to the treatment of GCT of tendon sheath. For recurrent and extra-articular soft-tissue disease adjuvant therapy, including intra-articular radioactive colloid or moderate-dose external beam radiotherapy, should be considered.

Surgery is considered to be the most effective treatment for cartilaginous tumours. In recent years, a trend has emerged for patients with low-grade tumours to be treated less invasively using curettage followed by various forms of adjuvant therapy. We investigated the potential for phenol to be used as an adjuvant. Using a human chondrosarcoma-derived cartilage-producing cell line OUMS-27 as an in vitro model we studied the cytotoxic effect of phenol and ethanol. Since ethanol is the standard substance used to rinse phenol out of a bone cavity, we included an assessment of ethanol to see whether this was an important secondary factor with respect to cell death. The latter was assessed by flow cytometry.

A cytotoxic effect was found for concentrations of phenol of 1.5% and of ethanol of 42.5%. These results may provide a clinical rationale for the use of both phenol and ethanol as adjuvant therapy after intralesional curettage in low-grade central chondrosarcoma and justify further investigation.

Low-grade surface tumours of bone may theoretically be treated by hemicortical resection, retaining part of the circumference of the cortex. An inlay allograft may be used to reconstruct the defect. Since 1988 we have performed 22 hemicortical procedures in selected patients with low-grade parosteal osteosarcoma (6), peripheral chondrosarcoma (6) and adamantinoma (10).

Restricted medullary involvement was not a contraindication for this procedure.

There was no evidence of local recurrence or distant metastasis at a mean follow-up of 64 months (27 to 135). Wide resection margins were obtained in 19 patients. All allografts incorporated completely and there were no fractures or infections. Fractures of the remaining hemicortex occurred in six patients and were managed successfully by casts or by osteosynthesis. The functional results were excellent or good in all except one patient.

Hemicortical procedures for selected cases of low-grade surface tumours give excellent oncological and functional outcomes. There was complete remodelling and fewer complications when compared with larger intercalary procedures. The surgery is technically demanding but gives good clinical results.