Objective To summarize the mid- to long-term effectiveness of total hip arthroplasty (THA) in the treatment of the involved hips in patients with ankylosing spondylitis (AS), and to investigate its influencing factors. Methods Between March 1999 and May 2011, 32 patients (42 hips) with AS and involved hip underwent THA. There were 26 males and 6 females with a mean age of 39 years (range, 20-78 years). The disease duration ranged from 2 to 41 years, with a median of 10 years. Metal-on-polyethylene bearings were used in 19 hips, and ceramic-on-ceramic bearings in 23 hips. The diameter of prosthetic femoral head was 36 mm in 15 hips and was 28 mm in 27 hips; and all the prostheses were fixed biologically. The Harris score, visual analogue scale (VAS) score, and total range of motion (ROM) of the hip were compared between at pre- and post-operation to evaluate the effectiveness. The DeLee zone was used for describing acetabular prosthesis, the Gruen zone for describing femoral prosthesis, and the Brooker criterion for evaluating the heterotopic ossification. Results Healing of incision by first intention was achieved in all patients after operation. There was no complication of anesthetic accident, infection, or neurovascular injury. Twenty-nine cases (39 hips) were followed up 5-17 years (mean, 9 years). Anterior dislocation of hip joint occurred in 2 hips of 24 hips (28 mm diameter), but did not in 15 hips (36 mm diameter). At last follow-up, the Harris score, VAS score, and the total hip ROM were significantly improved (P<0.05). The shorter the disease duration was, the higher postoperative Harris score and the greater postoperative total hip ROM would be (P<0.05); the bigger diameter of prosthetic femoral head was, the greater postoperative total hip ROM would be (P<0.05). All the acetabular components and femoral stems were well fixed at last follow-up. The osteolysis rate around the acetabular cup in the metal-on-polyethylene bearing group (50%, 9/18) was higher than that in the ceramic-on-ceramic bearing group (0, 0/21). No prosthetic loosening was observed in 2 groups. Seven hips were found to have heterotopic ossification, including 5 hips of Brooker grade I and 2 hips of Brooker grade II. Conclusion THA is an effective method to treat involved hips in patients with AS; especially for patients having shorter duration of the disease, THA shows better effectiveness when the bigger diameter of prosthetic femoral head and ceramic-on-ceramic bearing are used.
ObjectiveTo explore the influence factors of anterior bone loss (ABL) after cervical disc arthroplasty (CDA) and effects of ABL on the clinical and radiographic outcomes.MethodsOne hundred and fifty-five patients who underwent single-level Prestige-LP CDA between January 2008 and December 2017 and met the inclusive criteria were enrolled in the study. Perioperative data of patients were collected. The Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), and the visual analogue scale (VAS) score were used for clinical outcomes evaluation. Radiographic parameters including cervical lordosis, C2-7 range of motion (ROM), disc angle, segmental ROM, and the lengths of the upper and lower endplates were assessed on the X-ray films. Device-related complications, including ABL, subsidence, radiographic adjacent segment pathology, and heterotopic ossification, were recorded. Univariate analysis was used to analyze the related factors, and logistic regression analysis was used to screen the influence factors. Patients were grouped according to whether ABL occurred after operation, and the differences in clinical and imaging evaluation parameters were compared.ResultsThere were 94 cases (60.6%) in the ABL group and 61 cases (39.4%) in the non-ABL group. Univariate analysis showed the significant differences in age, body mass index (BMI), and intraoperative blood loss between the two groups (P<0.05). However, there was no significant difference in gender, bone mineral density (T value), preoperative blood calcium level, preoperative blood phosphorus level, preoperative alkaline phosphatase level, operative segment, operative time, and follow-up time between the two groups (P>0.05). Multivariate analysis showed that the age and BMI were influence factors for ABL after CDA (P<0.05). The JOA score, NDI, and VAS score significantly improved in both groups at 3 months after operation (P<0.05), and the scores were further improved at last follow-up (P<0.05). There was no significant difference in JOA score, NDI, and VAS score between the two groups before and after operation (P>0.05). The preoperative cervical lordosis was significantly smaller in the ABL group than in the non-ABL group (t=−2.402, P=0.018). At last follow-up, the segmental ROM was significantly greater in the ABL group than in the non-ABL group (P<0.05), and the lengths of the upper and lower endplates were less in the ABL group than in the non-ABL group (P<0.05). No significant difference in the other radiographic parameters between the two groups were found (P>0.05). Prosthesis subsidence occurred in 5 cases (3.2%), including 3 cases in the ABL group and 2 cases in the non-ABL group; the difference between the two groups was not significant (P=1.000). Heterotopic ossification occurred in 67 cases (43.2%), including 32 cases in the ABL group and 35 cases in the non-ABL group; the difference between the two groups was significant (χ2=8.208, P=0.004). High-grade heterotopic ossification was detected in 26 cases (13 cases in the ABL group and 13 cases in the non-ABL group). Twenty-nine cases (18.7%) had radiographic adjacent segment pathology, including 15 cases in the ABL group and 14 cases in non-ABL group; the difference between the two groups was not significant (χ2=1.190, P=0.276).ConclusionThe incidence of ABL after CDA was relatively high, which mainly occurred within 3 months after operation, and no longer progressing with stable radiographic features after the first 12 months. Age and BMI were independent influence factors for ABL. ABL does not affect the clinical outcomes but may preserve more ROM of prostheses.