Prevalence of radiographic parameters on CT associated with femoroacetabular impingement in a Chinese asymptomatic population.

BACKGROUND: Imaging evaluation of femoroacetabular impingement (FAI) plays a major role in early diagnosis and treatment, preventing irreversible degenerative changes in hip joints. PURPOSE: To investigate the anatomical parameters associated with FAI in a Chinese asymptomatic population by computed tomography (CT) and to evaluate the prevalence of the radiographic features of cam and pincer types in Chinese patients. MATERIAL AND METHODS: We reviewed the CT images of 470 hips in 235 Chinese patients who underwent abdominal and pelvic CT scans for reasons unrelated to hip symptoms at our hospital between February and October 2017. The following measurements were made on each hip joint: acetabular version angle (AV); anterior acetabular sector angle (AASA); posterior acetabular sector angle (PASA); the lateral center edge angle (LCE); the alpha angle (AA); and femoral head-neck offset (FHNO). RESULTS: Significant differences in all parameters were seen between men and women. Young men and elderly women showed more retroversion in our study. LCE, AA, and FHNO were all larger in men than women. The data showed 25% of female joints and 34.5% of male joints had at least one predisposing factor for FAI using measurement parameters by CT images in Chinese asymptomatic patients, and the prevalence of pincer lesion (19.1%) was larger than cam lesion (9.1%). CONCLUSION: Morphological features associated with FAI are also present in Chinese asymptomatic patients. The threshold values for abnormal parameters should be reconsidered based on gender, age, and other factors in order to improve the accuracy of diagnosis.

Comparative Mid-term Follow-up Study of Primary Total Hip Arthroplasty with Metal-on-metal and Metal-on-polyethylene Bearings.

OBJECTIVE: To compare mid-term clinical results of total hip arthroplasty (THA) with metal-on-metal (MoM) and metal-on-polyethylene (MoP) bearings and to evaluate the biological safety of the two kinds of prostheses. METHODS: Thirty-two patients who received a primary THA with an MoM articulation between January 2008 and December 2010 were selected to form the MoM group retrospectively. The MoP group consisted of 32 patients who received a THA with an MoP prosthesis during the same period. Clinical assessments, imaging examinations, laboratory tests, and metal ion concentration detections were conducted on each patient. Another 32 healthy volunteers were recruited as the control group. RESULTS: Twenty-seven patients in the MoM group and 28 patients in the MoP group completed the follow-up, with a mean follow-up time of 74.6 and 75.9 months, respectively. The mean Harris score at the latest follow-up was 91.5 ± 5.1 in the MoM group versus 88.9 ± 4.0 in the MoP group (P = 0.22). The MoM group showed a better range of motion in flexion, abduction, and external rotation. Co and Cr levels in the MoM group were 2.5-fold and 2.0-fold of these in the MoP group. A mild change of liver function was observed in both groups, while the values of renal function and humoral immunity stayed static. Elevated proportions of Th1 and Th17 cells and decreased proportion of Th2 cells were observed in the MoM group. The occurrence rate of pseudotumors in the MoM and MoP groups was 40.74% ± 9.45% and 14.28% ± 6.61%, respectively (P < 0.05). CONCLUSION: At the mid-term follow-up, clinical results were satisfied in both groups. MoM prosthesis could result in elevated serum metal ion levels and there is a higher risk of pseudotumor. Long follow-up is needed to evaluate the safety of MoM prostheses.

Treatment for Periprosthetic Cyst after Total Hip Arthroplasty: Analysis of Six Cases.

The present study investigates the pathogenesis of periprosthetic cysts after total hip replacement, and explores appropriate treatment appoaches. Six patients with periprosthetic cysts after total hip arthroplasty were treated at the First Affiliated Hospital of Nanjing Medical University between 2009 and 2014. During surgery, it was found that all cysts communicated with the hip and the hip prosthesis could be seen after cyst excision. Four patients simply underwent cyst excision, and light red liquid was found in the cyst. Among them, radiological examination revealed that a part of the hip prosthesis projected from the bone bed in one case. Postoperative pathology revealed a synovial cyst with inflammatory cell infiltration. Prostheses were loosened in two cases, so cystectomy and revision of the prosthesis were performed at the same time. Among the six patients, polyethylene wear particles could be seen in five patients through a pathological polarizing microscope. Out of the four patients who underwent simple cyst excision, two patients experienced cyst recurrence within 1 year after surgery; however, there was no cyst recurrence in the two patients who underwent cyst excision and revision of the prosthesis. The formation of a periprosthetic cyst after hip replacement is likely to be related to polyethylene wear and undesirable prosthesis position; in addition, when treated by simple cyst excision, the rate of recurrence was higher.