Short Time Experience with the Xpand Non-Invasive Expandable Endoprosthesis

Since July 2012 we have used the Xpand prosthesis in 15 skeletally immature patients to avoid and/or correct limb length discrepancy (LLD) in patients who underwent long bone resection involving the Femur or Tibia due to a primary bone sarcoma. Indications for use of were expected LLD of more than 3 cm or existing LLD exceeding 3 cm and a minimal resection length of 15 cm.

The study group consists of 9 male and 6 female patients diagnosed with Osteosarcoma or Ewing Sarcoma and involvement of the hip or knee joint. There were 12 cases of distal femur resection, one proximal femur and two proximal tibia.

Of 15 patients, 12 are alive, of which one with metastatic lung disease. Three patients died of disseminated disease. Average lengthening of 3.3 cm (range 0-6 cm) was achieved during 28 months of follow-up (range 3-46). Five implants were revised to insert a longer segment when maximum extension was achieved. Deep infection that necessitated implant removal occurred in two patients (after implant revision). 50% have equal leg length, while all other patients have not reached equal length yet. There were three mechanical failures, of which two have been revised. As a group all patients except two ambulate without assistance (short time follow-up), and have good knee function with except for two, One recurrence has occurred. The MSTS score for six patients with equal leg length is 24 (range 19-27).

The Mutars Xpand provides good function and proper leg length with a minimal need for surgical interventions. A major concern is the amount of mechanical failures (3 out of 12) that necessitated revision surgery. The minimal resection length of 17 cm in order to obtain 5 cm of lengthening makes the use of this implant in small tumors problematic.