Subclinical Hypothyroidism Affects Postoperative Outcome of Patients Undergoing Total Knee Arthroplasty.

OBJECTIVE: The aim of this study was to investigate whether subclinical hypothyroidism could increase the risk of postoperative complications in patients undergoing primary total knee arthroplasty (TKA). METHODS: A prospective case-control study of 796 patients undergoing primary TKA between January 2015 and January 2020 was performed. A total of 700 patients (87.9%) were female and the average age of included patients was 65.0 years, with a standard deviation of 5.6. The participants who had subclinical hypothyroidism were referred to as the case group, while those without abnormal thyrotropin (TSH) were included in the control group (matched for age and gender). The fasting plasma levels of TSH were tested in the morning in all patients. The diagnosis of subclinical hypothyroidism was completed by a senior endocrinologist based on laboratory tests; namely, a serum TSH ≥ 5 mu/L and normal free thyroxine (FT4). Subclinical hypothyroidism was further described as mild (TSH < 10 mu/L) or severe (TSH ≥ 10 mu/L). The incidence of 90-day postoperative complications was compared between two cohorts. Logistic regression analysis was used for the risk factors of 90-day postoperative complications following TKA. RESULTS: A total of 398 patients had a diagnosis of subclinical hypothyroidism. Among them, 275 cases (69.1%) were described as mild (79 patients [19.8%] with low FT4 and 196 patients [49.2%] with normal FT4 in the repeated test) and 123 cases (30.9%) as severe subclinical hypothyroidism. Of the 196 patients (49.2%) with mild subclinical hypothyroidism and normal FT4, 63 patients (15.8%) had symptoms before surgery. Patients were followed up for an average duration of 25.4 months (6 to 43 months). A total of 265 patients (66.6%) received preoperative treatment for subclinical hypothyroidism, with an average therapy time of 9.2 months. There were 162 patients (40.7%) with positive autoantibodies to thyroid peroxidase (anti-TPO). There were no statistically significant differences in baseline data between cohorts (all P > 0.05). As for the cumulative 90-day outcomes, subclinical hypothyroidism increased the incidences of both medical and surgical complications following primary TKA compared to those without this condition (11.6% vs 7.2%, OR = 1.55, 95% confidence interval [CI] = 1.47-1.62, P < 0.05). Subclinical hypothyroidism caused patients to suffer increased total incidence of readmission within the first 90 days after discharge when compared to those without this condition (20.61% vs 14.15%, OR = 1.45, 95% CI = 1.41-1.49, P < 0.001). Controlling for preoperative and intraoperative variables, the patients with TSH ≥ 10 mu/L and positive anti-TPO and those without corrected subclinical hypothyroid and thyroid hormone supplementation were more likely to experience postoperative complications within 90 days of TKA. CONCLUSION: Subclinical hypothyroidism might increase the risk of postoperative complications within 90 days of TKA, especially for the patients with TSH ≥ 10 mu/L and positive anti-TPO and those without corrected subclinical hypothyroid and thyroid hormone supplementation.

A radiologic parameter that could be applied in the development of sleep apnea in rheumatoid arthritis patients undergoing occipitocervical fusion.

BACKGROUND: The prevalence of sleep apnea in rheumatoid arthritis (RA) patients with occipitocervical lesions was 79%. Occipitocervical fusion (OCF) could incur sleep apnea or worsen this condition. Recent studies reported that this complication is caused by stenosis of the oropharyngeal airway accompanying a decrease in the occipitoaxial angle (O-C2a). However, there are several limitations to the application of the O-C2a, which decreases its effectiveness. Therefore, we aimed to evaluate the association between a new radiologic parameter, the CVT/NSL angle (CVT: craniocervical inclination in the second and fourth vertebrae; NSL: Nasion-Sella line), and sleep apnea in RA patients accepting OCF. METHODS: A total of 35 patients who underwent OCF due to upper cervical lesions secondary to RA and had sleep apnea before surgery were analyzed. Those who have a postoperative apnea-hypopnea index (AHI) < 15 and a ΔAHI ≥50% were considered "responders"; patients were otherwise considered "non-responders." They were analyzed whether pre- and postoperative radiologic parameters and their differences in plain lateral radiographs were correlated to the parameter related to sleep apnea. RESULTS: The included patients have a mean AHI of 21.9 (range, 10 to 52) before surgery. The mean postoperative CVT/NSLa, ΔCVT/NSLa, andΔO-C2a in complete responders were significantly greater compared with non-responders (p < 0.05). Both the changes in the CVT/NSLa and O-C2a were linearly correlated within patients. However, the R2 value for the CVT/NSLa was greater compared with the O-C2a (0.403 vs. 0.203). CONCLUSIONS: The usefulness of the new craniovertebral angle, CVT/NSLa, as an intraoperative indicator during OCF, is more valuable in comparison with the conventional method of measuring the O-C2a. Measuring the craniovertebral angle is extremely important in the planning of surgical treatment for the development of sleep apnea in rheumatoid arthritis patients undergoing occipitocervical fusion.

New Classification and Its Value Evaluation for Atlantoaxial Dislocation.

OBJECTIVE: To introduce the TOI classification system (the Traction reduction type [T type], Operation reduction type [O type], and Irreducible type [I type] classification system) and to determine the interobserver and intraobserver reliability of the TOI classification system. METHODS: Based on the characteristics of atlantoaxial dislocation (AAD), AAD was divided into Traction reduction type (T type), Operation reduction type (O type), and Irreducible type (I type). The analysis of interobserver and intraobserver agreements was done using kappa statistics. From July 2016 to January 2019, 213 AAD patients were retrospectively studied at four hospitals. Plain radiographs including extension and flexion views and three-dimensional CT images were obtained. Twenty independent observers, including eight experienced spine specialists and 12 orthopaedic fellows from four different residency training hospitals, completed the survey. RESULTS: The classification of the TOI system was based on etiology, the course of the disease, flexion-extension X-rays, three-dimensional CT reconstruction, and curative effects of skull traction. Flexion-extension X-rays demonstrating a successful reduction of the dislocated atlantoaxial joint and three-dimensional CT images showing osseous fusion of atlantoaxial facet joints and cervical traction reveal characteristics of T-type. Furthermore, this type can be divided into two subtypes, T1 and T2, according to the etiology and course of the disease. Unsatisfactorily reduction after 1-2 weeks of strict cervical traction, no reduction shown on flexion-extension X-rays, and no destruction or boneless fusion of atlantoaxial facet joints demonstrated in three-dimensional CT images are characteristics of type O. Atlantoaxial facet joint showing bone fusion or failure of reduction after cervical traction or three-dimensional CT images showing failure of surgical release are characteristics of type I. Interobserver and intraobserver reliability of the TOI classification system were moderate (κ = 0.543) and substantial (κ = 0.658), respectively. Interobserver and intraobserver reliability of the treatment choice were moderate (κ = 0.568) and substantial (κ = 0.675), respectively. There were no significant differences in the interobserver and intraobserver reliability between experienced spine specialists and fellows for all κ-values (P > 0.05). CONCLUSIONS: The TOI classification system had satisfactory reliability and, therefore, can be applied clinically and used by less experienced surgeons. We believe TOI can help surgeons choose appropriate treatment strategies.