Delayed formation of a devastating granulomatous process after metal-on-metal lumbar disc arthroplasty.

STUDY DESIGN:A case report. OBJECTIVE:We report the case of a female patient with a delayed and devastating complication after lumbar total disc arthroplasty (TDA). SUMMARY OF BACKGROUND DATA:The formation of granulomatous tissue surrounding arthroplasty devices has been described after hip replacements, but has been reported only in a few cases after spinal surgery. METHODS:Retrospective case study of a female patient with a delayed complication after lumbar TDA with a metal-on-metal device for degenerative disc disease at level L4-L5 and with follow-up examination 8 months after surgery. RESULTS:About 11 months after lumbar arthroplasty surgery, the patient developed back pain and progressive weakness of both legs. A computed tomographic scan revealed soft tissue surrounding the TDA device and infiltrating the spinal canal. The revision surgery (posterior fixation and decompression) did not improve the clinical situation. The progressive growth of soft tissue led to a high-grade paraparesis and occlusion of the left ureter as well as of both common iliac veins and the infrarenal part of the vena cava inferior. The TDA device was removed. Another posterior surgery with extensive instrumentation was necessary to treat the destruction of vertebral bodies L4 and L5 2 months after the last surgery. The histopathological analysis revealed a granulomatous necrotizing inflammation. After the last revision surgery, the patient's back pain decreased. At her last follow-up, no further growth of the soft tissue mass could be found. CONCLUSION:Metal-on-Metal TDA devices can induce a tumor-like growth with devastating consequences. The reduction of device motion by posterior stabilizing surgery does not seem to stop the growth of the granulomatous mass. The device has to be removed.