The Etiology of Cam-type Femoroacetabular Impingement: A Cadaveric Study.

BACKGROUND: There is a dearth of literature examining the causes of cam-type femoroacetabular impingement (FAI) and when such morphology appears. The purpose of the current study was to analyze how the ossific portion of the proximal femur develops over time with respect to standard cam-type FAI parameters. METHODS: A collection of 193 femurs from cadavers aged 4 to 21 years were evaluated. The age, sex, ethnicity, and status of the proximal femoral physes (open or closed) of each were recorded. Each specimen was digitally photographed in standardized anteroposterior and modified axial positions. From these photographs, the anterior offset, anterior offset ratio (AOR), and α-angle were determined. A cam lesion was defined as an α-angle >55 degrees on the lateral view. RESULTS: The mean age of the specimens was 17.5±4.2 years. The majority were male (69%) and African American (79%) with closed physes (78%). There were significant differences among discrete age groups with respect to α-angle (P=0.01), anterior offset (P<0.01), and AOR (P<0.01). In addition, younger femurs with open physes had a significantly higher mean α-angle (P<0.01), lower mean anterior offset (P<0.01), and higher mean AOR (P<0.01) compared with older ones with closed physes. Specimens defined as having a cam deformity had a statistically higher α-angle (P<0.01) and lower anterior offset (P<0.01), but there was no difference in AOR values compared with specimens without a cam lesion (P=0.1). CONCLUSIONS: The apparent decline in α-angles as age increases indicates that the traditional α-angle in younger patients measures a different anatomic parameter (ossified femur excluding the cartilaginous portion) than in older patients (completely ossified femur). This suggests that the bony α-angle is inappropriate in the evaluation of cam lesions in the immature physis. The AOR, rather than the anterior offset, may be more accurate in the evaluation of the growing proximal femur. CLINICAL RELEVANCE: This study provides novel insight into, and enhances the understanding of, the development of cam-type FAI.

Bone Marrow Edema: Chronic Bone Marrow Lesions of the Knee and the Association with Osteoarthritis.

Bone marrow edema of the knee occurs secondary to a myriad of causes. The hallmark of a bone marrow lesion (BML) is an area of decreased signal intensity on T1 weighted MRI with a corresponding area of increased signal intensity on a T2 weighted MRI. Recently, chronic bone marrow lesions have been correlated with knee pain and progression of osteoarthritis. These lesions have also been associated with other degenerative conditions such as meniscal tears, cartilage deterioration, subchondral cyst formation, mechanical malalignment, and ultimately progression to arthroplasty. Medical treatments, such as prostacyclin and bisphosphonate therapy, have shown promise. Alignment procedures, as well as core decompression and subchondroplasty, have been used as surgical treatments for chronic BMLs.

Hip arthroscopy outcomes, complications, and traction safety in patients with prior lower-extremity arthroplasty.

PURPOSE: Given the potential for injury due to joint-distraction techniques during hip arthroscopy, this study investigated the outcomes and safety of traction during hip arthroscopy in a series of patients with a prior lower-extremity arthroplasty. METHODS: Nine patients with a prior hip or knee arthroplasty (Group 1) and a matched cohort of nine additional patients with no prior hip surgery (Group 2) who underwent hip arthroscopy with traction between 2011 and 2013 were evaluated. Collected data included traction and operative times, Modified Harris Hip Scores (MHHS), Non-Arthritic Hip Scores (NAHS), and postoperative complications. RESULTS: Both operative (p = 1) and traction (p = 0.11) times were similar in each group. Each group had a significant improvement in MHHS from baseline to final follow-up: from 39 to 73 (p < 0.001) in Group 1 and from 49 to 75 (p = 0.03) in Group 2. Similarly, the NAHS showed significant improvement in each group from baseline to final follow-up: from 41 to 71 (p < 0.001) in Group 1 and from 48 to 74 (p = 0.02) in Group 2. There was no difference between groups in MHHS or NAHS. There was one postoperative complication in Group 1 (a recurrent labral tear) and no complications from an existing arthroplasty or in Group 2. CONCLUSIONS: Hip arthroscopy in patients with a lower-extremity arthroplasty yields improved short-term clinical outcomes without increased complications. The use of traction during hip arthroscopy is safe in this population.

Correlation of obesity with patient-reported outcomes and complications after hip arthroscopy.

PURPOSE: This study aimed to evaluate patient-reported outcomes and complications after hip arthroscopy in an obese population compared with a matched nonobese control group with a minimum 2-year follow-up, using the Modified Harris Hip Score (MHHS) and Nonarthritic Hip Score (NAHS). METHODS: Data were analyzed from 21 consecutive obese patients (body mass index [BMI] ≥ 30) and 18 nonobese patients (BMI < 25) who underwent hip arthroscopy between 2009 and 2012 with a minimum follow-up of 2 years. Data collected included MHHS, NAHS, traction and intraoperative times, and postoperative complications. RESULTS: Traction times were similar between obese and nonobese patients at 48 and 45 minutes (P = .51), respectively. Operative times were also similar at 54 and 51 minutes (P = .79), respectively. Each group had a statistically significant improvement in MHHS from baseline to final follow-up: 45 to 79 (P < .001) in the obese group and 49 to 81 (P < .001) in the nonobese cohort. Similarly, the NAHS showed significant improvement in each group from baseline to final follow-up: 43 to 75 (P < .001) in the obese cohort and 45 to 83 (P < .001) in the nonobese group. There was no difference between groups in MHHS or NAHS data. There were 8 complications in the obese group, most commonly deep vein thrombosis (DVT) and worsened pain, whereas the nonobese cohort had one complication (an instance of heterotopic ossification [HO]). Overall, obese patients had 11.1 times the risk of a complication developing than did nonobese patients (95% confidence interval, 1.2 to 99.7). CONCLUSIONS: Hip arthroscopy in the obese patient population leads to improved short- to mid-term patient-reported outcomes similar to those seen in nonobese patients. Obese patients, however, are at a significantly increased risk of postoperative complications such as DVTs and worsened hip pain. LEVEL OF EVIDENCE: Level IV, therapeutic case series.