Dubousset Functional Test: An Objective Test to Assess Function and Balance in Spine Patients
by Elizabeth Hofheinz, M.P.H., M.Ed., November 21, 2019
Things—and people—can come crashing down when they are disabled with a spinal pathology. Famed French orthopedic surgeon Jean Dubousset, who introduced the “cone of balance,” knew this well and developed a straightforward test to determine a patient’s functional capacity.
Recent multicenter work published in Clinical Orthopaedics and Related Research, “The Dubousset Functional Test is a Novel Assessment of Physical Function and Balance,” aimed to go beyond the typical quality-of-life questionnaires used to assess functioning and coordination in spine patients.
Co-author Bassel Diebo, M.D. is an orthopaedic surgery resident at the Department of Orthopaedic Surgery and Rehabilitation Medicine, State University of New York, Downstate Medical Center in Brooklyn, New York. He commented to OSN, “When it comes to adult spinal deformities, we know that in addition to manifesting as structural bony malalignment, there are other vital issues involved. These include deterioration of the muscles of the spine, pelvis, or lower limbs, as well as problems with balance.”
“The Dubousset Functional Test (DFT) is a functional test with four components: the Up and Walking Test (rising from a chair that does not have arms and walking 5 meters forward and 5 meters backward), the Steps Test (climbing steps), Down and Sitting Test (sitting down on the floor from a standing position), Dual-Tasking Test (participant walks while simultaneously counting down from 50). DFT measures the time it takes every subject or patient to perform each test. Our hypothesis is that DFT measures the patient functionality and quality of life in an objective way that complements the radiographic parameters and patient-reported outcomes.”
The authors wrote, “The rationale for using the Up and Walking and Steps Tests is that they were found to correlate with functional impairment and predict surgical outcomes. The Down and Sitting Test may help evaluate the patient’s ability to rise to an erect, bipedal, and balanced posture. Dr. Dubousset thought the Dual-Tasking Test was important because any interference between mental activity and postural control may be related to global body capacity. We believe that timing each of these tests is important (as opposed to, for example, seeing whether a patient can simply complete them or complete them in a reasonable amount of time) because it helps adjust performance by demographic variables such as age, gender, and comorbidities. It also enables us to investigate improvements before and after treatments as well as study minimal clinically important differences in future studies.”
Asking what drew the team to this topic, Dr. Diebo stated, “The main driver of our research is to understand what Dr. Dubousset summarized in one sentence ‘Balance is alignment in motion.’ Spinal alignment was the first component that we tackled for the past decade. Today we have an adequate understanding of the radiographic and postural alignment of the spine and lower limbs. However, understanding the dynamic and functional assessment of this complex remains a goal to be achieved.”
The prospective study, performed at one institution, took place from January 1, 2018 to May 31, 2018. All volunteers were asymptomatic and did not report any musculoskeletal problems or trauma within the past previous years. Also, none reported a history of lower limb fracture, THA, TKA, or patellofemoral arthroplasty. All four components of the DFT were timed.
Dr. Diebo: “As with every novel measure or test, research often starts with the normative or reference data based on asymptomatic subjects. The next step is to apply the DFT on patients with spinal pathologies and assess the deviation of time spent to perform the test versus the normative value. Our hypothesis is that the larger the patient deviates from the average amount of time it takes an age and gender adjusted control to perform the DFT, the worse this patient functionality, muscle envelope and global balance/coordination.”
Asked how this work best assists practicing spine surgeons, Dr. Diebo commented to OSN, “DFT aims to quickly be an applicable tool in spine care. Due to the simplicity of the test and established safety, the team believe that the patient performance of DFT may provide an objective measure of postoperative improvement of patient functionality. In addition, due to its assessment of muscle envelope and global balance, DFT could be a predictor of patient’s ability to maintain spinal realignment procedures, mechanical complications like proximal junctional kyphosis and revision surgeries.”
