gms | German Medical Science

Objective: Patients following total hip (THA) or knee (TKA) arthroplasty are known to show deficits in the range of motion of hip extension at ground contact [1], knee flexion during weight acceptance [1], [2] and knee extension in the push-off phase [1], [2]. However, research has focused mainly on deficits of the operated limb in comparison to healthy controls, whereas the non-operated limb is seldom considered. But inter-limb differences in gait kinematics after arthroplasty might result in a premature deterioration of the healthy limb [1]. Therefore, the objective of this investigation was to present sagittal hip and knee kinematics of both the operated and non-operated limb that allow for an inter-limb comparison and serve as a reference to evaluate future patients rehabilitation progress.

Material/Methods: 447 patients (M237, W210, 66.9 (±8.6) yrs, 173 (±9) cm, 80.5 (±16.4) kg) underwent gait analysis at the end of their stationary rehabilitation 28 (±6) days following a total joint replacement of the hip (THA, n=275, 137 left, 138 right) or knee (TKA, n=172, 91 left, 81 right). Kinematic data were collected in a routine gait analysis setup. At least ten steps of each leg were analysed while patients walked barefoot on an 8m runway back and forth at their preferred walking speed. Kinematics were recorded at 45Hz with a three camera kinematics system (Lukotronic, Austria) and projection angles in sagittal plane were determined using the company’s proprietary algorithm. Total range of motion of the hip extension (Hext-rom), knee flexion (Kflex-rom), and knee extension (Kext-rom) were afterwards calculated using Matlab 2008 (Mathworks, USA). Inter-limb differences in kinematic parameters were analysed using paired student t-tests (α=.05).

Results: Since no differences in the kinematics were found between patients with arthroplasty on their left or right limb, data of the operated limbs (OP) respectively non-operated limbs (NON) were combined. As expected, THA patients showed significant reduction in hip and knee extension of the OP limb compared to the NON limb. Inter-limb asymmetries were found in hip and knee extension in patients regardless of the operated joint (THA: reduced Hext-rom, Kext-rom/TKA: increased Hext-rom, reduced Kext-rom). Range of motion in knee flexion (Kflex-rom) of both limbs was low compared to literature values for THA and TKA patients [1], [2], [3], [4]. In inter-limb comparison, however, no differences were found (Figure 1 [Fig. 1]).

Conclusion: One possible explanation for the fact that inter-limb asymmetries become apparent only in hip and knee extension is that reduced knee flexion during weight acceptance results in higher impacts. These impacts are perceivable by patients and might lead to adaptation of knee flexion on both sides to regain symmetrical impacts. Differences in limb extension, on the other hand, might not be perceivable and, therefore, it can be difficult for the patients to correct them. In an effort to relearn symmetrical gait following arthroplasty, patients might be dependent on external feedback of deficits in their limb extension. The presented data set can be used as reference data to evaluate the progress of rehabilitation following hip or knee arthroplasty. The data set should be supplemented with kinematics collected later in the rehabilitation process.