Poster 61: Focal dystonia of the hamstring after total knee replacement: a case report

Abstract

Setting: Outpatient musculoskeletal clinic. Patient: A 75-year-old man with dystonia of the left hamstring, after bilateral total knee replacements (TKRs). Case Description: The patient had bilateral, severe degenerative joint disease of his knees. After bilateral TKR, he developed focal dystonia of the left hamstring muscles. Assessment/Results: Abdominal aortogram and left lower-extremity arteriogram, for a left knee hemarthrosis, were significant only for moderate right renal artery stenosis. The patient underwent an evacuation of a left knee hematoma and synovetomy. After multiple attempts at aggressive therapy and extension splinting, no significant improvement was noted. The patient continued to have symptoms, which were increased nocturnally. Magnetic resonance imaging of the lumbosacral spine for radicular etiology revealed degenerative joint disease of L3-S1 with mild disk bulge throughout. Epidural steroid injections yielded no measurable improvement. The patient continued to have marked restriction in range of the left knee, with palpable spasm of the left hamstring muscles and gait difficulty. Range of motion (ROM) was 30° to 95°. Oral medications, cyclobenzaprine (Flexeril) and baclofen, did not improve his range. 100U of botulinum toxin were injected into 5 areas of the left hamstring muscles with excellent results. The patient gradually regained a functional range of 3° to 130°, which was maintained at a 9-month follow-up after the injection. Discussion: To our knowledge, focal dystonia has not been described in the literature as a complication of TKR. In this case, botulinum toxin was used to treat hamstring dystonia after physical therapy, splinting, and oral medications failed. ROM and functional gait were restored. Conclusion: Use of botulinum toxin to restore functional ROM in a patient with focal dystonia after TKR should be studied further.