Femoroacetabular impingement is more common in military veterans with end-stage hip osteoarthritis than civilian patients: a retrospective case control study

Background: The purpose of this study was to compare the frequency of femoroacetabular impingement(FAI) between matched groups of military veterans and civilian patients with end-stage hip osteoarthritis(OA).Methods: Patients who underwent a primary total hip arthroplasty(THA) between January 1, 2015 and December 31, 2015 at a single Veteran’s Affairs Hospital were identified. Veterans were then matched 1:2 with civilian patients from our prospective outcome registry. The alpha angle and lateral center-edge angle(LCEA) were measured by a single evaluator. Independent t-tests were used to compare joint angles, and Fisher exact tests were used to compare the prevalence of cam(alpha angle ≥60°), pincer(LCEA ≥40°), or mixed-type pathologies.Results: Twenty-one veterans were matched 1:2 with civilian patients. The mean alpha angle did not significantly differ between groups(P=0.33) nor did the prevalence of cam deformities(P=0.79). The LCEAs were significantly greater in veterans than in civilians(P=0.04), and veterans also demonstrated a significantly greater prevalence of pincer and mixed-type deformities than civilians(P=0.025 and P=0.004, respectively).Conclusions: These results suggest that FAI is perhaps a more common mechanism in the progression of OA in a veteran population than in a civilian population, as pincer and mixed-type deformities were significantly more common among veterans than civilians. The forces borne by the hip during military training exceed normal physiologic conditions. In addition, the time between symptom onset and surgical correction may be 10–12 months longer for active military personnel than for civilians. The combination of increased physical demands and a protracted time to treatment highlights the need for better recognition of FAI in military members. Future studies are necessary to determine whether earlier intervention may prevent or delay the progression to end-stage OA and the need for total hip arthroplasty.

Corrections in alpha angle following two different operative approaches for CAM-type femoral acetabular impingement-Ganz surgical hip dislocation vs anterior mini-open

BACKGROUND Femoroacetabular impingement(FAI)is a predisposing factor for secondary osteoarthritis of the hip joint.The two extensively described impingement mechanisms of FAI are CAM and Pincer-type.Initially managed conservatively,operative intervention should be offered to the persistently symptomatic patient.The measurement of the alpha angle is considered a standard method of assessing the severity of pathology in Cam-type FAI on pre-operative plain radiographs.The radiological correction of the alpha angle has not been previously compared between different surgical approaches.We hypothesize that there is no difference in alpha angle correction between Ganz surgical hip dislocation and the anterior mini-open approach.AIM To compare the magnitude of alpha angle correction achieved by using the Ganz surgical hip dislocation and the anterior mini-open approach.METHODS This is a retrospective study assessing seventy-nine patients identified in a 5-year period.These patients had preoperative radiographic evidence of FAI and underwent surgery by a single surgeon at our institution,a tertiary care center.Patients with missing radiographic documentation,radiographs with insufficient quality which then precluded accurate measurement of the angleα,a diagnosed congenital condition,isolated type II pathology(Pincer),and history of prior surgery were excluded from the study.Either the Ganz surgical hip dislocation or the anterior mini open approach was used.Postoperative radiographic evaluation of the alpha angle between the two surgical methods was done and corrected for age and gender using two-sample t-tests and Chi-square analyses.RESULTS A total of 79 patients met the inclusion and exclusion criteria.Forty-seven males(mean age of 35.3,range 16-53)and 32 females(mean age 36.7,range 16-60)were enrolled.Forty-seven patients underwent the anterior mini-open approach,and 32 underwent the Ganz surgical hip dislocation.There were no significant differences in age between the two surgical groups or in pre-and post-operative alpha angles based on patient gender.The mean pre-operative alpha angle for the Ganz surgical hip dislocation group was 88.0 degrees(SD 12.3)and 99.4 degrees(SD 7.2)for the anterior mini-open group.Mean post-operative angles were 49.9 degrees(SD 4.3)for the Ganz surgical hip dislocation and 43.8(SD 4.3)degrees for the anterior mini-open group.There was a statistically significant difference in patient’s pre-operative and post-operative angles(P=0.000)with both surgical approaches.CONCLUSION Statistically significant decreases in alpha angle were noted for both surgical techniques,with larger decreases seen in the anterior mini-open group.