Abstract
Background: Knee immobilization is a common intervention for patients with traumatic injuries. However, it usually leads to biomechanical/morphological disturbances of articular tissues. These changes may contribute to declining kinetic friction-related quality of arthrokinematics; however, this phenomenon has not been analyzed in vivo and remains unrecognized. Thus, the aim of the present study is to investigate the effect of immobilization and subsequent re-mobilization on the quality of arthrokinematics within the patellofemoral joint, analyzed by vibroarthrography (VAG). Methods: Thirty-four patients after 6-weeks of knee immobilization and 37 controls were analyzed. The (VAG) signals were collected during knee flexion/extension using an accelerometer. Patients were tested on the first and last day of the 2-week rehabilitation program. Results: Immobilized knees were characterized by significantly higher values of all VAG parameters when compared to controls (p < 0.001) on the first day. After 2 weeks, the participants in the rehabilitation program that had immobilized knees showed significant improvement in all measurements compared to the baseline condition, p < 0.05. However, patients did not return to normal VAG parameters compared to controls. Conclusion: Immobilization-related changes within the knee cause impairments of arthrokinematic function reflected in VAG signal patterns. The alterations in joint motion after 6 weeks of immobilization may be partially reversible; however, the 2-week physiotherapy program is not sufficient for full recovery.
Highlights
Immobilization is a common orthopedic intervention for patients with severe traumatic injuries, and despite the benefit, immobilization usually leads to dysfunction in articular and extra-articular tissues of diarthrodial joints [1,2]
Joint immobilization and unloading result in chondral softening, proteoglycan loss and overall reduction of the cartilage thickness [8,9]. It seems that immobilization-related biomechanical and morphological disturbances lead to deterioration in range of motion (ROM) and contribute to declining quality of arthrokinematic motion, which refers to the palpatory sense of how smoothly a joint can be moved through its ROM [10,11,12]
Immobilized knees, when analyzed before rehabilitation, generate signals characterized by significantly higher values of amplitude parameters (VMS and R4), both in comparison to the contralateral, non-immobilized side and to the knees of the control group. It is seen on the representative plots of the VAG signals, where the knees after immobilization were characterized by higher amplitude and variability of the signal as compared to healthy subjects (Figure 1)
Summary
Immobilization is a common orthopedic intervention for patients with severe traumatic injuries, and despite the benefit, immobilization usually leads to dysfunction in articular and extra-articular tissues of diarthrodial (synovial) joints [1,2] One of these dysfunctions is joint contracture, which is characterized by loss of passive range of motion (ROM), and is a common clinical problem in orthopedics and rehabilitation medicine [3,4]. Joint immobilization and unloading result in chondral softening, proteoglycan loss and overall reduction of the cartilage thickness [8,9] It seems that immobilization-related biomechanical and morphological disturbances lead to deterioration in ROM and contribute to declining quality of arthrokinematic motion, which refers to the palpatory sense of how smoothly a joint can be moved through its ROM [10,11,12]. The alterations in joint motion after 6 weeks of immobilization may be partially reversible; the 2-week physiotherapy program is not sufficient for full recovery
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