title: Physical capability outcomes after total disc replacement with ProDisc-L.
abstract: BACKGROUND
  Lumbar disc arthroplasty (total disc replacement [TDR]) outcomes have been evaluated using subjective, patient-reported measures of pain, health, and functional impairment. As a condition of TDR coverage, our institution's health plan required that objective physical performance data be collected. Thus our study was designed to explore (1) the feasibility of using preoperative and 1-year postoperative performance on functional capacity tasks as an outcome metric for TDR with ProDisc-L (PD-L) (Synthes Spine, West Chester, Pennsylvania), (2) the magnitude and significance of changes in preoperative and postoperative performance, and (3) whether changes noted in performance are reflected in the subjective measures.
  
  
  METHODS
  Seven adapted WorkWell tasks (physical capability assessment tool [PCAT]) (WorkWell Systems, Duluth, Minnesota) were performed preoperatively and 1 year postoperatively by 18 patients who received either single-level or 2-level PD-L implants. Demographic and medical data were reviewed.
  
  
  RESULTS
  The PCAT was implemented easily, and the tasks took approximately 30 minutes to complete. Percent improvement and preoperative and postoperative physical capability outcomes for each PCAT task are as follows: squat, 79% (10.7 ± 7.1 repetitions vs 19.2 ± 2.0 repetitions, P < .001); forward bend, 121% (110.2 ± 68.8 seconds vs 243.6 ± 77.2 seconds, P < .001); kneel, 92% (283.2 ± 173.2 seconds vs 544.7 ± 109.3 seconds, P < .001); floor-to-waist lift, 128% (16.1 ± 9.9 lb vs 36.7 ± 20.3 lb, P < .001); horizontal carry, 119% (19.7 ± 8.6 lb vs 43.2 ± 18.3 lb, P < .001); push, 32% (67.7 ± 19.2 lb vs 89.4 ± 24.4 lb, P < .001); and pull, 40% (57.6 ± 17.1 lb vs 80.9 ± 26.4 lb, P < .001). Visual analog scale scores for pain (5.1 ± 1.7 vs 1.4 ± 1.6, P < .001), Oswestry Disability Index scores (49.0% ± 13.2% vs 15.2% ± 14.3%, P < .001), and amount of narcotic use (26.1 ± 43.8 mg of morphine equivalent vs 1.9 ± 7.3 mg of morphine equivalent, P = .031) also improved. In single-level cases, comparison of L4-5 versus L5-S1 showed significant differences only with the forward bend task (P = .002).
  
  
  CONCLUSIONS
  The physical capability outcome may be a feasible outcome metric. PD-L implantation may result in substantial improvements in physical performance. Similar benefits shown in a larger series over a longer timeframe could have important implications for the long-term health, productivity, and cost of health care for this patient population.
authors.affiliation: Department of Neurosurgery, Gundersen Lutheran Health System, La Crosse, WI.
authors.forename: Humbert G
authors.initials: HG
authors.lastname: Sullivan
authors.affiliation: Department of Industrial Rehabilitation, Gundersen Lutheran Health System, La Crosse, WI.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Bobenmoyer
authors.affiliation: Department of Neuropsychology, Gundersen Lutheran Health System, La Crosse, WI.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Boland
authors.affiliation: Department of Neurosurgery, Gundersen Lutheran Health System, La Crosse, WI.
authors.forename: Molly M
authors.initials: MM
authors.lastname: Cerniglia
authors.affiliation: Department of Medical Research, Gundersen Lutheran Medical Foundation, La Crosse, WI.
authors.forename: Vicki L
authors.initials: VL
authors.lastname: McHugh
authors.affiliation: Department of Medical Research, Gundersen Lutheran Medical Foundation, La Crosse, WI.
authors.forename: Hayley L
authors.initials: HL
authors.lastname: Born
authors.affiliation: Department of Medical Research, Gundersen Lutheran Medical Foundation, La Crosse, WI.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Mathiason
authors.affiliation: Department of Medical Research, Gundersen Lutheran Medical Foundation, La Crosse, WI.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Ladwig
keywords: Disc arthroplasty; Outcome assessment; ProDisc-L; Total disc replacement