Optimal Treatment of Cam Morphology May Change the Natural History of Femoroacetabular Impingement

Abstract

Background: There is debate in the literature whether cam morphology is associated with increased risk for hip osteoarthritis. The capability of femoroplasty to alter the natural history of cam morphology is still in question. Purpose: To (1) investigate the correlation between cam morphology and damage to the articular cartilage and (2) assess whether correction of the cam morphology affects survivorship of the joint, progression to arthroplasty, and functional patient-reported outcome scores. Study Design: Cohort study; Level of evidence, 3. Methods: Data were prospectively collected for patients presenting for hip arthroscopy between February 2008 and April 2017. Cases were divided into 3 groups: control group with an alpha angle <50° pre- and postoperatively, treated group with an alpha angle >55° preoperatively and <50° postoperatively, and a group with an alpha angle >55° pre- and postoperatively. All patients had minimum 2-year postoperative follow-up for the modified Harris Hip Score, the Non-arthritic Hip Score, and visual analog scale for pain. Conversion to total hip arthroplasty was recorded. Results: A 1:1:1 match successfully yielded 98 hips for each group. Follow-up time was 50.77 ± 24.60 months (mean ± SD). The pre- and postoperative mean alpha angles were 45.2°± 3.4° and 40.6°± 4.3° in the control group, respectively; 66.2°± 8.4° and 42.3°± 5.9° in the treated group; and 68.5°± 9.4° and 61.4°± 7.6° in the alpha >55° group. Intraoperatively, the alpha >55° and treated groups had greater acetabular cartilage damage than the control group ( P = .0245 and P = .0036, acetabular labrum articular disruption, respectively; P = .0347 and P = .0211, acetabular Outerbridge). The alpha >55° group achieved the patient acceptable symptomatic state for the modified Harris Hip Score (58.2%) significantly less than the treated (75.5%; P = .0100) and control (73.5%; P = .0239) groups. Progression to arthroplasty was significantly higher in the alpha >55° group (n = 17) when compared with the control (n = 8) and treated (n = 10) groups ( P = .0034 and P = .0338, respectively). Conclusion: Cam deformity was associated with higher-grade damage of the acetabular articular cartilage. An alpha angle >55° after surgery was associated with lower native hip joint survivability and less successful functional outcomes when compared with that of treated cam deformity as well as no deformity. These data suggest that correcting the cam deformity may positively affect the natural history of these patients.

Hips 2021

“…This interpretation of the FIRST trial results is supported by another recent AJSM publication by Domb et al 4 In that retrospective cohort study, the authors divided hip arthroscopy patients into 3 matched groups according to their pre- and postoperative alpha angle measurements: those whose alpha angle was <50° both before and after surgery, those whose alpha angle was >55° before surgery and <50° afterward, and those whose alpha angle was >55° both before and after surgery. At the time of surgery, both groups with elevated preoperative alpha angles, which averaged 66°-69°, were noted to have more labral and acetabular cartilage damage than the third group, whose mean preoperative alpha angle was only 50°.…”

Imaging of the Hip

“…The three major osseous factors for the development of FAI are often seen in combination and not as isolated entities [19]. When evaluated individually, the literature shows that the risk of subsequent hip osteoarthritis is highest in the presence of a cam deformity, while this association is less well established for isolated pincer deformities and abnormal femoral antetorsion [1].…”

“…Moreover, in patients scheduled for surgery, the assessment of joint damage allows the stratification of patients into those with only minor and peripheral joint damage -these individuals can expect a good long-term outcome after arthroscopic surgery. Patients with more central lesions of the articular cartilage or widespread joint damage may choose to undergo surgery for pain relief, but the surgical procedure will not allow to prevent or delay osteoarthritis in those patients [1].…”

“…While hip joint damage was commonly evaluated in conditions such as developmental dysplasia of the hip or osteoarthritis, an additional condition for early onset hip osteoarthritis has been discovered since: femoroacetabular impingement (FAI). New biomechanical insights and improved techniques for hip preservation surgery have triggered the need for imaging evaluation of patients with suspected FAI [1].…”

Retrospective Analysis of Arthroscopic Cam Decompression. Is Hip Joint Still Preserved Although at Learning Curve?

“…Whereas most recently, level of evidence increased indicating that cam morphology of femoral head (asphericity) leads to development of hip osteoarthritis due to acetabular chondral damage (3)(4)(5)(6)(7) . Supporting this, Domb et al (7) also reported that in patients treated with hip arthroscopy and optimal resection, cam deformity (postoperative α angle<55 0 ) had lower incidence of conversion to total hip arthroplasty than incomplete resection (postoperative α>55 0 ). A recent in vitro study also confirmed that accurate cam resection restored normal peak joint contact stresses (8) .…”