[Effect of Primary and Revision Total Hip Arthroplasty on Gait Kinematics]

PURPOSE OF THE STUDY The number of patients with total hip arthroplasty (THA) has been growing. In addition to traumatic indication, the patients manifest abnormalities in kinematics and kinetics of gait preoperatively. The aim of the study was to assess kinematics of the pelvis and lower limbs during walking in patients with unilateral primary and revision THA. MATERIAL AND METHODS A total of 18 patients (10 females, 8 males) with primary THA (pTHA) as well as 18 patients (9 males, 9 females) with revision THA (rTHA) participated in the study. The control group (CON) comprised 19 healthy subjects (11 females, 8 males). Kinematic data were collected using the optoelectronic motion system Vicon MX. Kinematic parameters were obtained by means of 16 reflective markers placed on the patient's body in correspondence with the Plug-in Gait model. All the patients also underwent a clinical examination (evaluation of the surgery result, patient's satisfaction assessment, Harris score evaluation) and a specific X-ray evaluation of both hips. RESULTS The analysis brought the following results: - non-operated limb (NL) in pTHA vs. rTHA: significantly smaller total range of motion (ROM) in the hip joint (36.4° vs 41.7°) in the sagittal plane, - operated limb (OL) in pTHA vs. rTHA: significantly greater values of maximum knee flexion (14.2° vs. 9.8°) and extension (7.9° vs. 4.0°), - NL in pTHA vs. CON: significantly smaller ROM in the knee (51.0° vs. 57.9°) and hip (36.4° vs. 43.6°) joints in the sagittal plane, - OL in pTHA vs. CON: significantly smaller knee flexion (52.9° vs. 57.6°), hip extension (-0.6° vs. -10.4°), and the total ROM in the knee (51.5° vs. 57.9°) and hip (34.5° vs. 43.6°) joints in the sagittal plane, - NL in rTHA vs. CON: significantly greater pelvis ROM in both the sagittal (5.6° vs. 3.1°) and transverse (12.1° vs. 9.9°) planes, - OL in rTHA vs. CON: significantly smaller total ROM in the knee (48.9° vs. 57.9°) and hip (31.4° vs. 43.6°) joints in the sagittal plane. DISCUSSION After THA surgery, various gait pathologies as well as compensatory mechanisms can develop and chain; therefore, a complex approach to physical therapy in THA patients is needed. The number of significant differences found in kinematic parameters between pTHA and rTHA was low a year after the surgery. Compared to CON, both the THA groups exhibited similar mechanisms causing worsening their gait dynamics. CONCLUSIONS Gait in both the THA groups was characterized by a decreased ROM in the knee and hip joints in the sagittal plane, compensated by increased pelvic anteversion. Approximately one year after THA surgery, the NL is still noticeably dominant in gait. The changes in lower limb mechanics after revision THA persist even after a considerable time since the surgery. Key words: primary total hip arthroplasty, revision total hip arthroplasty, gait, range of motion, pelvic kinematics, biomechanics.