Aims

Computer hexapod assisted orthopaedic surgery (CHAOS), is a method to achieve the intra-operative correction of long bone deformities using a hexapod external fixator before definitive internal fixation with minimally invasive stabilisation techniques.

The aims of this study were to determine the reliability of this method in a consecutive case series of patients undergoing femoral deformity correction, with a minimum six-month follow-up, to assess the complications and to define the ideal group of patients for whom this treatment is appropriate.

We reviewed 234 benign solitary schwannomas treated between 1984 and 2004. The mean age of the patients was 45.2 years (11 to 82). There were 170 tumours (73%) in the upper limb, of which 94 (40%) arose from the brachial plexus or other nerves within the posterior triangle of the neck. Six (2.6%) were located within muscle or bone. Four patients (1.7%) presented with tetraparesis due to an intraspinal extension.

There were 198 primary referrals (19 of whom had a needle biopsy in the referring unit) and in these patients the tumour was excised. After having surgery or an open biopsy at another hospital, a further 36 patients were seen because of increased neurological deficit, pain or incomplete excision. In these, a nerve repair was performed in 18 and treatment for pain or paralysis was offered to another 14.

A tender mass was found in 194 (98%) of the primary referrals. A Tinel-like sign was recorded in 155 (81%). Persistent spontaneous pain occurred in 60 (31%) of the 194 with tender mass, impairment of cutaneous sensibility in 39 (20%), and muscle weakness in 24 (12%).

After apparently adequate excision, two tumours recurred. No case of malignant transformation was seen.