PRACTICAL SIGNIFICANCE
Gaining full comprehension of the joint mechanics in knee OA patients during stair climbing is essential for understanding functional deficits, providing optimal treatment and rehabilitation, as well as extending the quality of life in patients that suffer from this debilitating disease.

STUDY BACKGROUND
Osteoarthritis (OA) is a common musculoskeletal condition affecting an estimated 27 million Americans. Specifically, tibiofemoral joint OA is the most common form due to the consistent joint loading the knee joint complex receives throughout one’s lifespan. We are entering an era where knee OA is being diagnosed in epidemic proportions; further, it is becoming more evident that further research is needed to fully understand lower extremity joint mechanics during a common daily task such as stair climbing in patients who suffer from knee OA. Not only is gaining a better understanding of how knee OA directly influences knee joint mechanics during stair gait critical, but so too is understanding how hip and ankle joint mechanics may also be affected during stair gait.

OBJECTIVE
To compare various hip, knee and ankle joint kinematic variables between knee OA subjects and matched healthy controls during stair ascent and descent.

DESIGN AND SETTING
A case-controlled, crossover design was used to study subjects performing 5 ascending and descending stair gait trials while lower extremity joint motion was captured three dimensionally in a Biodynamics Research Laboratory.

SUBJECTS
Eighteen subjects with knee OA (age 60.17 ± 9.98 yrs, mass 90.27 ± 16.73 kg, ht 168.41 ± 9.92 cm) and 18 healthy matched controls (age 60.28 ± 10.66 yrs, mass 81.12 ± 21.21 kg, ht 168.28 ± 11.95 cm) participated in the study.

MEASUREMENTS
Sagittal and frontal plane hip, knee and ankle kinematics: average angle at foot strike (°), peak angle during support (°), time of peak angle during support (%), peak angle during swing (°), time of peak angle during swing (%) and average angle at toe off (°) during stair ascent and stair descent was measured using an optical video motion capture system (Figure 1).

RESULTS
Significant group by direction interactions were found for average hip flexion angle at foot strike [P = 0.041], average ankle adduction angle at foot strike [P =0.007], and peak ankle dorsiflexion angle during swing [P= 0.015]. Specifically, knee OA and control subjects demonstrated greater hip flexion angle at foot strike and ankle dorsiflexion angle during swing during stair ascent compared to descent. Further, knee OA patients demonstrated greater hip abduction at foot strike (-3.08° ± 3.94) and smaller peak knee flexion during swing (86.73° ± 5.43). The time of peak hip abduction (34.18% ± 7.07), peak knee flexion (69.84% ± 4.57) and peak ankle adduction (37.27% ± 20.77) during support and the time of peak hip flexion (85.22% ± 3.7), peak knee flexion (77.67% ± 3.75) and ankle dorsiflexion (80.73% ± 4.50) angle during swing occurred later in the gait cycle for knee OA patients compared to control subjects.  Figures 2 & 3 demonstrate knee joint kinematics during stair ascent and descent.

CONCLUSIONS
These data demonstrate that knee OA directly influences specific knee joint kinematics. Pathological deviations at the knee appear to induce kinematic alterations at the hip and ankle perhaps in an effort to compensate for the existing knee joint pathology.

Figure 1: Customized staircase used for lower extremity 3D joint kinematic analysis during stair ascent and descent.

Back to November 14, 2012 eBlast Newsletter
 

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