Abstract
BackgroundHip involved secondary to ankylosis spondylitis (AS) had a huge influence on hip function. Cementless total hip arthroplasty (THA) can improve hip function. However, no previous study compared the outcomes of THA for AS patients with three different degrees of hip involvement.MethodsThe 195 hips were retrospectively analyzed and divided into non-ankylosed group (group A, 94 hips), fibrous ankylosed group (group B, 49 hips), and bony ankylosed group (group C, 52 hips). postoperative range of motion (ROM), harris hip scores (HHS), the short-form 12 health survey (SF-12), length of stay (LOS), cost, radiological assessments, and complications were compared.ResultsThe follow-up time was (79.4 ± 29.5) months for group A, (80.6 ± 28.9) months for group B, and (79.1 ± 28.9) months for group C (P = 0.966). Group A had the best postoperative hip ROM (P < 0.001), while group A and B can realize better HHS than group C (P < 0.001). The three groups had similar SF-12 postoperatively. For group A, LOS and cost for unilateral procedure were the least than that for group B and C (P = 0.003 and P = 0.001). Similar radiological assessments were achieved for three groups. 1 hip in group A encountered delay union of wound. 1 hip in group C encountered delay union of wound and dislocation and another patient encountered femoral fracture intraoperatively. 12 hips (12.8%) in group A, 6 hips (12.2%) in group B, and 6 hips (11.5%) in group C encountered asymptomatic heterotopic ossification (P = 0.977).ConclusionFor AS patients with hip involvement, THA can improve hip ROM and function. THA for the non-ankylosed hip can realize the better hip function and postoperative ROM than ankylosed hip.
Highlights
Ankylosing spondylitis (AS) diagnosed using the modified New York criteria [1] is an inflammatory disease affecting the axial spine and peripheral joints, characterized by low back pain, limited range of motion (ROM) of the lumbar spine and hip joint involved, and resulting inMou et al J Orthop Surg Res (2021) 16:608 characteristics for ankylosis spondylitis (AS) patients [5]
According to the different severities of hip lesions, three different lesions can emerge including non-ankylosed hip [6, 9, 10], fibrous ankylosed hip [11,12,13], and bony ankylosed hip [10,11,12, 14, 15], which were defined as no total loss of hip ROM, no continuous bony trabecula passing through the hip joint on X-ray with 0°hip ROM, and continuous bony trabecula bridging the hip joint on X-ray with 0°hip ROM
Patients The inclusion criteria: patients diagnosed with AS and performed cementless total hip arthroplasty (THA); hip involved secondary to AS; no total loss of hip ROM regarded as non-ankylosed group; no continuous bony trabecula passing through the hip joint on X-ray with 0°hip ROM regarded as fibrous ankylosed group; continuous bony trabecula passing through the hip joint on X-ray with 0°hip ROM regarded as bony ankylosed group
Summary
Ankylosing spondylitis (AS) diagnosed using the modified New York criteria [1] is an inflammatory disease affecting the axial spine and peripheral joints, characterized by low back pain, limited range of motion (ROM) of the lumbar spine and hip joint involved, and resulting inMou et al J Orthop Surg Res (2021) 16:608 characteristics for AS patients [5]. Different degrees of lesions caused by AS showed various changes of soft tissue, which may result in different influences on hip function even if total hip arthroplasty (THA) was performed. Literature has reported the clinical and radiographic outcomes of THA for AS patients They have different limitations such as small sample size [10,11,12, 14], short-term follow-up [5, 14], various implanted prostheses or fixation techniques [9, 15], and confounded results of bony and fibrous ankylosed hips [11, 12, 16]. No previous study compared the outcomes of THA for AS patients with three different degrees of hip involvement
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