Postural stability and functional disorders in patients with loosened hip prosthesis

The number of primary hip arthroplasties is growing every year. One of the most common long complications is the aseptic loosening of the prosthesis leading to serious complications in patients life, pain and following surgeries. In the literature, there is a lack of studies regarding balance impairment in this group of patients, which is why there was a need to conduct the study in order to find possible falling risk factors and simple functional, diagnostic test. The aim of the study was to assess functional state and static balance disorders in patients admitted to orthopaedic department due to loosened hip prosthesis prior to its replacement or removal.

The study population were 30 patients (15 women and 15 men) admitted to Orthopaedic Department for diagnosis and treatment of loosened hip prosthesis. Patients' mean age was 71.67 ± 9.21, body height 169.20 ± 8.75 cm, body weight 77.83 ± 12.96 kg. The clinical control group consisted of 30 healthy subjects age-, body height- and weight-matched, without degenerative disorders of lower extremities. Function was assessed with Harris Hip score. The static balance test was conducted in the mornings, in quiet separate room on bi-modular stabilometric platform CQStab2P, registering the movement of centre of foot pressure (COP).

Measurements with eyes open and closed showed significant differences in limb loads - the load to the healthy limb was several times greater. Results of tests on the platform with eyes closed showed significantly worse balance in patients group. Their total statokinesiogram path was longer, and their COP sways number was greater. Similarly to the test with eyes open, the load of the healthy limb was much greater.

Hip replacement loosening results in significant worsening of balance parameters. Balance assessment could be an additional useful diagnostic tool for hip replacement loosening available for physiotherapists.