Abstract
Background
The patients with high hip dislocation due to the sequelae of septic hip or neglected Developmental Dysplasia of the Hip (DDH) show severely impaired gait pattern. Total hip arthroplasty (THA) for these patients are expected to restore gait pattern by establishing better joint stability and biomechanics. To our knowledge, no study have investigated about objective change in gait parameters after total hip arthroplasty (THA) for these patients. So, we are to prospectively evaluate change in gait patterns after THA.
Methods
Between 2012 and 2013, 11 patients with highly dislocated hip underwent unilateral THA with subtrochanteric osteotomy. There was 6 patients with DDH sequelae and 5 patients with septic hip sequelae. Spatio-temporal gait analysis was performed preoperatively and at 12 months after THA. We followed the patient 3, 6, 12 months and then annually postoperatively. The gait patterns were analyzed by several parameters such as cadence, speed, stride length, step length, step time, initial double support (IDS), terminal double support (TDS), stance phase and swing phase by a three-dimensional (3D) high-speed motion-capturing system (eight Eagle® cameras; Motion Analysis, Santa Rosa, CA, USA). Also dynamic range of motion (ROM) of hip joint and ground-reaction forces (GFR) were recorded. Clinical outcome was evaluated by using the Harris Hip Score (HHS). Radiographic assessments were evaluated for the changes in leg length discrepancy (LLD).
Results
For operated limb, the mean period of TDS significantly increased from 8.6 % to 11.3 % respectively (p=0.038). As IDS, single support and TDS improved, mean period of stance phase increased from 54.4 % to 60.1 % of gait cycle and swing phase was relatively reduced from 45.4% to 39.9% (p=0.005) On the other hand, there were decrease in cadence, speed, step length on the affected limb postoperatively (p>0.05). In force graph, all patients showed significant increase of the peak force postoperatively. The first peak force (Fz1) was improved from 0.76 N (0.60 – 0.98) to 0.95 N (0.79 – 1.16) (p=0.007). The second peak force (Fz2) was improved from 0.70 N (0.44–0.96) to 0.94 N (0.85 – 1.14) (p=0.007). For the dynamic ROM, there were increase in sagittal plane motion and decrease in transverse and coronal plane. All of the changes were significantly not difference than preoperatively. Clinically, mean HHS was improved from 57.2 (range, 43–67) to 79.6 (range, 61–88) at last follow-up (p<0.05). In radiographic assessment, the patients showed 9.8 mm (range, 2.1 – 22.1) residual LLD at last follow-up.
Conclusions
In the present study, patients with high hip dislocation who underwent primary THA showed improvement of gait pattern closer to that of normal hip joint. Although the patients showed improvement in gait analysis and clinical outcomes, but do not reach normal hip joint level and showed little residual antalgic gait pattern after THA.
