Computed tomographic appearances of the pelvis following hindquarter amputation

Magnetic resonance imaging appearances following hindquarter amputation for pelvic musculoskeletal malignancy

OBJECTIVE

To describe our experience of the magnetic resonance imaging (MRI) appearances after hindquarter amputation, focusing on the normal pattern of time-related changes in signal intensity within the amputation flap and appearances of local disease recurrence.

MATERIALS AND METHODS

This was a retrospective review of the records of patients identified on our orthopaedic oncology database who had undergone hindquarter amputation at our centre. Examinations were divided into one group consisting of 'normal' postoperative findings and another group demonstrating local recurrence. 'Normal' postoperative findings were assessed for signal intensity, morphology and presence of the 'muscle texture sign' within the amputation flap. Examinations were grouped according to time from surgery. Examinations demonstrating local recurrence were assessed for site, signal intensity, morphology and axial dimensions of recurrent tumour. Comparison was made to pre-operative imaging.

RESULTS

Thirty-five patients with postoperative MR images were identified. Seventy-seven examinations were reviewed (range 1-18 per patient). The 'normal group' comprised 18 patients (seven female, 11 male, mean age 44 years, range 16-75 years), with 47 examinations reviewed. The 'muscle texture sign' was preserved in all examinations in this group. Up to 6 months after surgery, 100% (10) of examinations showed hyperintense T2- and short-tau inversion recovery (STIR-weighted) signals within the muscle flap, indicating oedema. Only after 4 years was the muscle flap signal isointense in all cases (13). Up to 6 months after surgery, 50% (5 of 10) of examinations demonstrated flap swelling, but after 1 year, 100% (28) showed atrophy. Twenty percent (2 of 10) of examinations 0-6 months from surgery showed hyperintense T1-weighted signal within the muscle flap, consistent with fatty infiltration, but after 2 years, 100% (20) showed a hyperintense T1-weighted signal. The 'local recurrence' group comprised 20 patients (six female, 14 male, mean age 45.7 years, range 14-69 years), with 30 examinations demonstrating recurrent disease or metastasis. There were 23 recurrent tumours, of which 43% (10) were in the muscle component of the amputation flap, 13% (3 of 23) were in subcutaneous tissues of the flap, 13% (3 of 23) were at the posterior margin of the bone resection and 13% (3 of 23) were paraspinal. All recurrent tumours demonstrated hyperintense T2 and STIR signals. The signal intensity pattern of recurrence closely followed that of the original tumour. The 'muscle texture sign' was absent in all examinations demonstrating recurrence in muscle flap.

CONCLUSION

A pattern of time-related signal intensity and morphological changes is observed within normal hindquarter amputation flaps on MRI. Recurrent disease is most likely to occur within the muscle flap, typically of high T2-weighted signal intensity and characteristically follows the signal pattern of the original tumour.

Amputation for soft-tissue sarcoma

Soft-tissue sarcomas are a group of rare malignant tumours, many of which arise in the limbs. Most are treated with a combination of wide local excision and radiotherapy, but a small number--including proximal, large, high-grade, or recurrent tumours, or those involving major neurovascular structures--necessitate major amputation including forequarter or hindquarter amputation. These uncommon operations should remain in the surgical armamentarium for carefully selected patients. Those being considered for amputation should be referred to a tertiary sarcoma unit for examination of all other options, such as limb-salvage surgery, tumour downstaging with chemotherapy or radiotherapy (perhaps with subsequent limb-salvage surgery), or novel techniques such as isolated limb perfusion. Only after careful assessment should amputation be carried out. Outcomes after major amputation are highly variable, but such procedures can confer useful palliation to patients with distressing symptoms (pain, bleeding, fungation), long-term disease-free survival with reasonable function in carefully selected patients, and cure in some.

Major amputation for soft-tissue sarcoma

BACKGROUND

Advances in oncological practice have reduced the number of major amputations performed for soft-tissue sarcoma, but this remains a valuable, if infrequent, option for both curative and palliative indications.

METHODS

A review of patients and case-notes was carried out from the prospective sarcoma database at the Royal Marsden Hospital.

RESULTS

Over a 10-year interval, 40 major amputations (18 forequarter, 17 hindquarter and five through hip) were performed, predominantly for disease recurring after previous limb-conserving surgery (31 of 40). A wide variety of soft-tissue sarcoma subtypes was seen; they were often large (more than 10 cm; 18 of 40) or multifocal (six), usually high grade (25), and frequently proximal or involving neurovascular structures such that limb salvage was precluded. Median range age of the patients was 59 (17-87) years. The operative 30-day mortality rate was zero. Hospital stay was a median of 10.5 days for forequarter amputation, and 19 days for hindquarter and through-hip amputation. Local recurrence occurred in ten patients, six of whom had concurrent distant metastases. Twenty-seven patients were alive (20 disease free) at a median follow-up of 12 months, nine of whom were alive without evidence of disease beyond 2 years. Ten patients died after a median of 7.5 months; three survived more than 2 years.

CONCLUSION

Major amputation is a useful procedure in carefully selected patients with soft-tissue sarcoma.