Total hip arthroplasty in fused hips with spine stiffness in ankylosing spondylitis

Ankylosing spondylitis(AS)is characterized by involvement of the spine and hip joints with progressive stiffness and loss of function.Functional impairment is significant,with spine and hip involvement,and is predominantly seen in the younger age group.Total hip arthroplasty(THA)for fused hips with stiff spines in AS results in considerable improvement of mobility and function.Spine stiffness associated with AS needs evaluation before THA.Preoperative assessment with lateral spine radiographs shows loss of lumbar lordosis.Spinopelvic mobility is reduced with change in sacral slope from sitting to standing less than 10 degrees conforming to the stiff pattern.Care should be taken to reduce acetabular component anteversion at THA in these fused hips,as the posterior pelvic tilt would increase the risk of posterior impingement and anterior dislocation.Fused hips require femoral neck osteotomy,true acetabular floor identification and restoration of the hip center with horizontal and vertical offset to achieve a good functional outcome.Cementless and cemented fixation have shown comparable long-term results with the choice dependent on bone stock at THA.Risks at THA in AS include intraoperative fractures,dislocation,heterotopic ossification,among others.There is significant improvement of functional scores and quality of life following THA in these deserving young individuals with fused hips and spine stiffness.

Functional and clinical outcome with modified lateral approach total hip arthroplasty in stiff hips with ankylosing spondylitis

BACKGROUND Ankylosing spondylitis at total hip arthroplasty(THA)has significant hip stiffness with flexion deformity,restricted mobility,and function.Range of movement(ROM)improvement with good functional outcome is seen following THA in these hips.The modified Hardinge approach without abductor compromise is helpful in these stiff hips with associated flexion deformity.AIM To assess improvement in ROM and functional outcomes with a modified lateral approach THA in ankylosing spondylitis with stiff hips.METHODS A total of 69 hips that underwent THA with a modified Hardinge approach in 40 patients were evaluated at a mean follow-up of 38.33 mo.All individuals ambulated with weight-bearing as tolerated and ROM exercises from the 1st postoperative day.Modified Harris hip score and ROM were assessed during follow-up.Quality of life assessments using the 36-item and 12-item short form health surveys were done along with clinical and functional outcomes at followup.SPSS 22.0 was used for statistical analysis.The correlation of ROM and functional score change was performed using Pearson’s correlation coefficient.RESULTS Sixty-nine hips with a significant decrease in ROM preoperatively with 32 clinically fused hips showed significant improvement in flexion range.The mean flexion in 69 hips improved from 29.35±31.38 degrees to 102.17±10.48 degrees.The mean difference of 72.82 with a P value<0.0001 was significant.In total,45 out of 69 hips had flexion deformity,with 13 hips having a deformity above 30 degrees.The flexion during the follow-up was below 90 degrees in 3 hips.Eleven hips had flexion of 90 degrees at follow-up,while the remaining 55 hips had flexion above 100 degrees.Modified Harris hip score improved from 17.03±6.02 to 90.66±7.23(P value<0.0001).The 36-item short form health survey at the follow-up indicated health status in 40 patients as excellent in 11,very good in 20,good in 5,fair in 3,and poor in 1.The mean mental health score was 84.10±11.58.Pain relief was good in all 69 hips.Altogether,28/40 patients(70%)had no pain,9 patients(22%)had occasional pain,and 3 patients(8%)had mild to moderate pain with unusual activity.Heterotopic ossification was seen in 21 hips with Brooker class 1 in 14 hips.CONCLUSION Modified Hardinge approach THA in ankylosing spondylitis with stiff hips with flexion deformity significantly improved ROM,Harris hip score,and quality of life indicated by the 36-item and 12-item short form health surveys.