Radiographic Findings in the Lower Extremity Joints of Long-Term Users of Implanted Standing Neuroprostheses with Spinal Cord Injuries.

Objective: To assess whether lower extremity degenerative joint changes developed in long-term users of implantable neuromuscular prostheses.

Design: Before-after radiographic assessment.

Setting: Tertiary care center.

Participants: Four individuals (4 men, average age 46.5y, injuries ranging from C7-T11) with spinal cord injury resulting in lower extremity paraplegia were included for analysis. All individuals previously received surgery for the placement of a neuroprosthesis implant system. Individuals were followed with specific spinal cord injury outcome measures and radiographs in a prospective manner. Individual implant usage was also recorded as part of the standard treatment. These individuals were selected because they were in the highest tier for daily use of the implant system.

Interventions: Not applicable.

Main Outcome Measures: Development of degenerative joint pathology, based on analysis of pre- and post-therapy radiographs and grading using the Kellgren and Lawrence and Van Dijk scales.

Results: None of the joints for the individuals that were graded 0-2 (no or mild arthritis) progressed to a grade 3 (moderate arthritis). Further, none of the joints developed an arthritic grade of >3. Only 2 of the 24 total joints had statistically significant (<.05) degenerative changes: subject 1: right hip; =.033 (average grade increased from 0.875-1.875); subject 2: right hip; =.049 (average grade increased from 0.875-1.50).

Conclusions: At an average of 5 years after implantation, regular and independent weight bearing in 4 higher-than-average users of a neuromuscular prosthesis does not appear to promote lower extremity joint degeneration.