Arthroplasty in the military: a preliminary experience with ProDisc-C and ProDisc-L
Authors: Tumialán Luis M. , Ponton Ryan P. , Garvin Angelina , Gluf Wayne M. 
Published: February 2011

Object
The introduction of cervical and lumbar arthroplasty has allowed for management of cervical radiculopathy and lumbar degenerative disease in patients with the preservation of motion at the affected segment. While the early clinical outcomes of this technology appear promising, it remains unclear what activity limitations should be imposed after surgery in patients with these implants. This is of particular interest in military personnel, who may be required to return to a rigorous level of activity after surgery. The goals of the FDA trials evaluating various disc arthroplasty devices were to establish safety, efficacy, and equivalency to arthrodesis. Information regarding the level of physical performance attained and restrictions or limitations is lacking, as these were outside the objectives of these trials. Nevertheless, there data are essential for the military surgeon, who is tasked with guiding the postoperative management of patients treated with arthroplasty and returning them to full duty. While there is a single report of clinical results of lumbar arthroplasty in athletes, at this writing, there are no reports of either cervical or lumbar arthroplasty in active duty military personnel.

Methods
The surgical database at a single, tertiary care military treatment facility was queried for all activeduty patients who underwent placement of either a cervical or lumbar arthroplasty device over a 3-year period. The authors performed a retrospective chart review to collect patient and procedural data including blood loss, length of hospital stay, tobacco use, age, rank, complications, and ability to return to full unrestricted active duty. Arthroplasty cohorts were then compared to historical controls of arthrodesis to ascertain differences in the time required to return to full duty.

Results
Twelve patients were identified who underwent cervical arthroplasty. All patients returned to unrestricted full duty. This cohort was then compared with 12 patients who had undergone a single-level anterior cervical discectomy and fusion. The average time to return to unrestricted full duty for the arthroplasty group was 10.3 weeks (range 7–13 weeks), whereas that in the fusion group was 16.5 weeks. This difference between these 2 groups was statistically significant (p = 0.008). Twelve patients were identified who underwent lumbar arthroplasty. Ten (83%) of 12 patients in this group returned to unrestricted full duty. In patients who returned to full duty, it took an average of 22.6 weeks (range 12–29 weeks). This cohort was then compared with one in which patients had undergone anterior lumbar interbody fusion. Eight (67%) of 12 patients in the lumbar arthrodesis group returned to unrestricted full duty. In patients who returned to full duty, it took an average of 32.4 weeks (range 25–41 weeks). This difference was not statistically significant (p = 0.156).

Conclusions
The preliminary experience with cervical and lumbar arthroplasty at the authors' institution indicates that arthroplasty is comparable with arthrodesis and may actually expedite return to active duty. Patients are capable of returning to a high level of rigorous training and physical performance. There are no apparent restrictions or limitations that are required after 3 months in the cervical patient and after 6 months in the lumbar patient. Further prospective studies with long-term follow-up are indicated and will be of value when determining the role of arthroplasty compared to arthrodesis in the active-duty population.