Stephen K. Aoki

Radiographic prevalence of femoroacetabular impingement in collegiate football players: AAOS Exhibit Selection.

BACKGROUND The prevalence of femoroacetabular impingement may be greater in athletes than in the general population because of increased loading of the hip during sports. This study evaluated the radiographs of collegiate football players in order to quantify the prevalence of femoroacetabular impingement in asymptomatic athletes. METHODS Sixty-seven male collegiate football players (age, 21 ± 1.9 years) participated in this prospective study. Both hips (n = 134) were evaluated independently by two orthopaedic surgeons for radiographic signs of femoroacetabular impingement. The alpha angle and femoral head-neck offset were measured on frog-leg lateral radiographs. The lateral center-edge angle, acetabular index, crossover sign, and alpha angle were measured on anteroposterior radiographs. Data for continuous variables were averaged between observers prior to assessing prevalence. Cam femoroacetabular impingement was considered to be present if the femoral head-neck offset was <8 mm and/or the alpha angle was >50° on either radiograph. Pincer femoroacetabular impingement was considered to be present if the lateral center-edge angle was >40°, the acetabular index was <0°, and/or a positive crossover sign was detected by both observers. RESULTS Ninety-five percent of the 134 hips had at least one sign of cam or pincer impingement, and 77% had more than one sign. Twenty-one percent had only one sign of cam femoroacetabular impingement and 57% had both signs. Fifty-two percent had only one sign of pincer femoroacetabular impingement, 10% had two, and 4% had all three signs. Specifically, 72% had an abnormal alpha angle, 64% had a decreased femoral head-neck offset, 61% had a positive crossover sign, 16% had a decreased acetabular index, and 7% had an increased lateral center-edge angle. Fifty percent of all hips had at least one sign of pincer femoroacetabular impingement and at least one sign of cam impingement. Interobserver and intraobserver repeatability was moderate or better for each measure (range, 0.59 to 0.85). CONCLUSIONS Morphologic abnormalities associated with cam and pincer femoroacetabular impingement were common in these collegiate football players. The prevalence of cam and pincer femoroacetabular impingement was substantially higher than the previously reported prevalence in the general population.

The Effect of NSAID Prophylaxis and Operative Variables on Heterotopic Ossification After Hip Arthroscopy

Background: Heterotopic ossification (HO) is a known complication of hip arthroscopy. Little is known about the factors that lead to HO after hip arthroscopy. Purpose: The aim of this study was to evaluate the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) and other operative variables on the development of HO. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 357 consecutive cases of hip arthroscopy were retrospectively reviewed over a 3-year period. Routine NSAID prophylaxis was not performed for the first 117 cases. Prophylaxis with naproxen for 3 weeks was then routinely prescribed for the remaining 240 cases. Complete follow-up was available for 288 of the original 357 cases. The presence of HO and its characteristics were recorded for each patient, along with baseline demographic and surgical variables. Odds ratios and logistic regression were used to identify causal factors for HO. Results: The incidence of HO in cases in which the patient did not receive NSAID prophylaxis was 25.0% (23/92) versus 5.6% (11/196) of cases in which the patient received NSAIDs. Patients who received no NSAID prophylaxis were 13.6 times more likely to develop HO postoperatively (95% confidence interval, 2.44-75.5; P = .003). Comparing just mixed-type femoroacetabular impingement resections, patients who received no NSAID prophylaxis were 16.6 times more likely to develop HO postoperatively (95% confidence interval, 2.2-126.0; P = .006). Multivariate logistic regression identified the performance of a mixed-type femoroacetabular impingement resection (P = .011) and the absence of NSAID prophylaxis (P = .003) as predictors of HO development. The majority of HO cases (29/34) occurred in patients with mixed-type femoroacetabular impingement who had both osteochondroplasty and acetabuloplasty. Complications of NSAID therapy in this study population included acute renal failure, hematochezia from acute colitis, and gastritis. Conclusion: Routine NSAID prophylaxis reduces but does not eliminate the incidence of HO in patients undergoing hip arthroscopy. Heterotopic ossification was more likely to develop in patients undergoing acetabuloplasty along with osteochondroplasty and in those who did not receive prophylactic postoperative NSAIDs. Side effects from the investigated NSAID regimen can be serious and should be weighed against the potential benefits in preventing the formation of HO.

Youth sports anterior cruciate ligament and knee injury epidemiology: who is getting injured? In what sports? When?

The importance and benefits of exercise are well documented. With childhood obesity rates rising in most developed countries, encouraging outdoor play and sports participation may be one of several solutions for this problem. However, with the increased youth sport participation seen over the past 10 years, there has also been a need to monitor the risks of participation within this unique population. Unfortunately, only a few well-designed epidemiologic surveillance studies have been conducted thus far. The pediatric and adolescent population is unique in that their skeletal system is still maturing, and thus, they may be susceptible to unique injury patterns and injury frequency. The frequency and severity of sports injuries can differ based on the type of exposure (competition vs practice), sport, gender, and age. Recording these variables is important to accurately determine risk and obtain reliable epidemiologic data. To do this, standard definitions for injury and exposure should be established and widely accepted. Standardization of injury reporting will allow comparison of results across studies so the associated factors can be more thoroughly explored. The purpose of this article is to review the types and patterns of knee and anterior cruciate ligament (ACL) injuries for youth sports based upon recent research. Much of this review is based upon the extensive research of Comstock et al using data compiled from the National High School Sports-Related Injury Surveillance Study. 1 This article will focus on the

Coxa Profunda: Is the Deep Acetabulum Overcovered?

BackgroundCoxa profunda, or a deep acetabular socket, is often used to diagnose pincer femoroacetabular impingement (FAI). Radiographically, coxa profunda is the finding of an acetabular fossa medial to the ilioischial line. However, the relative position of the acetabular fossa to the pelvis may not be indicative of acetabular coverage.Questions/purposesWe therefore determined the incidence of coxa profunda and evaluated associations between coxa profunda and other radiographic parameters of acetabular coverage commonly used to diagnose pincer FAI and acetabular dysplasia.MethodsWe evaluated the radiographs of three cohorts for coxa profunda, lateral center edge (LCE) angle, acetabular index, posterior wall sign, and crossover sign. Data from 67 collegiate football players were collected prospectively (Cohort 1). We identified two patient cohorts through retrospective review of all 179 hips undergoing hip preservation surgery from 2002 to 2008 (83 periacetabular osteotomies [Cohort 2] and 96 surgical dislocation and osteochondroplasties [Cohort 3]).ResultsIn all three cohorts, we detected no difference in the LCE angle or acetabular index between hips with and without coxa profunda. Coxa profunda existed in hips representing the spectrum of acetabular coverage measured by LCE angle (−18° to 60°) and acetabular orientation determined by the crossover sign.ConclusionsCoxa profunda was a common radiographic finding in both symptomatic patients and asymptomatic football players. Coxa profunda existed in hips representing the spectrum of acetabular coverage and was not associated with an overcovered acetabulum. We conclude coxa profunda is unrelated to overcoverage and suggest its use in diagnosis of pincer FAI be abandoned in favor of other determinants of focal or general overcoverage.Level of EvidenceLevel III, diagnostic study. See Instructions for Authors for a complete description of levels of evidence.

Hip Internal Rotation Is Correlated to Radiographic Findings of Cam Femoroacetabular Impingement in Collegiate Football Players

PURPOSE The objective of this study was to determine whether physical examinations (flexion-abduction-external rotation [FABER], impingement, range-of-motion profiles) could be used to detect the bony abnormalities of femoroacetabular impingement (FAI) in an athletic population. METHODS We performed a prospective study of 65 male collegiate football players. Both hips were evaluated by 2 orthopaedic surgeons for radiographic signs of FAI. The alpha angle and head-neck offset were measured on frog-leg lateral films. The center-edge angle, acetabular index, crossover sign, and alpha angle were measured on anteroposterior films. Measurements were averaged for both observers. Maximum hip range of motion in flexion (supine) and internal/external rotation (supine, sitting, and prone) was measured with a goniometer. Pain provoked by the impingement and FABER tests was also recorded. Examinations were completed at 2 of 4 stations (2 duplicates), each staffed by 2 clinicians (1 examined and 1 measured). The relation between each range-of-motion and radiographic measure was determined. Data from each station were assessed separately. Only those regressions significant (P < .05) for paired stations were considered clinically significant. RESULTS The alpha angle and head-neck offset measured on the frog-leg lateral films were significantly correlated (all P < .01) to supine, sitting, and prone internal rotation for all stations. Correlation coefficients ranged from -0.59 to -0.35 for alpha angle and 0.42 to 0.57 for head-neck offset. Although 95% of the hips had at least 1 radiographic sign of FAI, pain was reported in only 8.5% and 2.3% during the impingement and FABER tests, respectively. CONCLUSIONS Internal rotation correlates to radiographic measures of cam FAI in this cohort of collegiate football players. Football players with diminished internal rotation in whom hip pain develops should be evaluated for underlying cam FAI abnormalities. LEVEL OF EVIDENCE Level IV, therapeutic case series.

Arthroscopic Capsular Repair for Symptomatic Hip Instability After Previous Hip Arthroscopic Surgery

Background: Management of the hip capsule has been a topic of recent debate in hip arthroscopic surgery. Postoperative instability after hip arthroscopic surgery has been reported and can lead to poor outcomes. Purpose: To determine the outcome of patients diagnosed with symptomatic instability after hip arthroscopic surgery at a minimum of 12 months and 24 months after revision surgery for capsular repair. Study Design: Case series; Level of evidence, 4. Methods: In a cohort of approximately 1100 patients who underwent hip arthroscopic surgery, 33 patients (33 hips) developed symptomatic instability requiring a revision surgery. Two patients suffered anterior dislocations following their initial surgery. Radiographs were reviewed to evaluate for acetabular dysplasia. Three patients were lost to follow-up and 10 patients were excluded as they were <1 year out from the revision surgery. A total of 20 patients (18 female, 2 male) completed a preoperative and postoperative modified Harris Hip Score (mHHS) and Hip Outcome Score (HOS) at a minimum of 12 months. Eleven of these patients had a minimum follow-up of 24 months. All patients filled out a Likert scale of perceived improvement in physical ability at final follow-up. Results: The mean age of the patients was 29.7 years (range, 15.2-55.5 years). The mean lateral center-edge angle was 25°, and the mean acetabular index was 7° before revision. All patients underwent interportal capsulotomy during the index arthroscopic procedure. After their index arthroscopic procedures, patients had minimal improvement at a mean of 19.1 months postoperatively on the mHHS (from 57.1 to 57.6; P = .423), HOS-Activities of Daily Living (ADL) (from 62.7 to 66.4; P = .260), and HOS-Sports (from 42.0 to 39.1; P = .800). For the patients with a minimum 1-year follow-up after revision surgery (n = 20; mean follow-up, 21.3 months), the mean mHHS (from 57.6 preoperatively to 85.8 at final follow-up; P < .001), HOS-ADL (from 66.4 to 85.7; P < .001), and HOS-Sports (from 39.1 to 79.8; P < .001) all improved significantly. The results were similar when looking at only the patients with a minimum 2-year follow-up after revision surgery (n = 11; mean follow-up, 26.1 months); the mean mHHS (from 56.0 preoperatively to 91.5 at final follow-up; P = .001), HOS-ADL (from 68.3 to 89.9; P = .009), and HOS-Sports (from 35.7 to 87.9; P = .001) all improved significantly. When comparing patients with isolated capsular repair to those with additional procedures performed, there were no differences between the groups (all P > .05). At final follow-up, all but 1 patient had improved overall physical ability levels. Conclusion: Revision hip arthroscopic surgery for capsular repair in patients with symptomatic instability after hip arthroscopic surgery provides good functional outcomes at a minimum of 1 and 2 years postoperatively.

Complications of cemented long-stem hip arthroplasties in metastatic bone disease.

It is controversial whether a cemented long-stem femoral arthroplasty is a safe surgical option for patients with meta-static bone disease of the hip. Cemented long stems increase the risk of embolic cascades and may cause subsequent cardiopulmonary complications, particularly in patients with metastatic disease. We retrospectively reviewed results of 29 long-stem cemented femoral arthroplasties in 27 patients in which surgical techniques that minimized intramedullary debris and canal pressurization were used. The surgical techniques minimized intraoperative cement-related emboli with aggressive medullary lavage, intraoperative canal suctioning during cementation, use of early low-viscosity polymethylmethacrylate, and slow, controlled insertion of the long-stem prosthesis. Cement-associated hypotension occurred in four (14%) patients, sympathomimetics were administered in nine (31%) patients, and a worsening mental status occurred postoperatively in one (3%) patient. There were no cement-associated desaturation events, cardiac arrests, or intraoperative deaths. No patients required prolonged intubation, and there were no postoperative cardiopulmonary events. Cemented long-stem femoral arthroplasty is a safe procedure for patients with high-risk metastatic disease. Increased awareness of cement-related cardiopulmonary pathophysiology, and modifying conventional surgical techniques can minimize cement-associated complications. Level of Evidence: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

The Prevalence of Radiographic Findings of Structural Hip Deformities in Female Collegiate Athletes

Background: Structural deformities of the hip, including femoroacetabular impingement (FAI) and acetabular dysplasia, often limit athletic activity. Previous studies have reported an increased prevalence of radiographic cam FAI in male athletes, but data on the prevalence of structural hip deformities in female athletes are lacking. Purpose: (1) To quantify the prevalence of radiographic FAI deformities and acetabular dysplasia in female collegiate athletes from 3 sports: volleyball, soccer, and track and field. (2) To identify possible relationships between radiographic measures of hip morphologic characteristics and physical examination findings. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Anteroposterior (AP) pelvis and frog-leg lateral radiographs were obtained from 63 female athletes participating in Division I collegiate volleyball, soccer, and track and field. Lateral center edge angle (LCEA) and acetabular index were measured on AP films. Alpha angle and head-neck offset were measured on frog-leg lateral films. Pain during the supine impingement examination and hip rotation at 90° of flexion were recorded. Random-effects linear regression was used for group comparisons and correlation analyses to account for the lack of independence of observations made on left and right hips. Results: Radiographic cam deformity (alpha angle >50° and/or head-neck offset <8 mm) was found in 48% (61/126) of hips. Radiographic pincer deformity (LCEA >40°) was noted in only 1% (1/126) of hips. No hips had radiographic mixed FAI (at least 1 of the 2 cam criteria and LCEA >40°). Twenty-one percent (26/126) of hips had an LCEA <20°, indicative of acetabular dysplasia, and an additional 46% (58/126) of hips had borderline dysplasia (LCEA ≥20° and ≤25°). Track and field athletes had significantly increased alpha angles (48.2° ± 7.1°) compared with the soccer players (40.0° ± 6.8°; P < .001) and volleyball players (39.1° ± 5.9°; P < .001). There was no significant difference in the LCEA (all P > .914) or the prevalence of dysplasia (LCEA <20°) between teams (all P > .551). There were no significant correlations between the radiographic measures and internal rotation (all P > .077). There were no significant differences (all P > .089) in radiographic measures between hips that were painful (n = 26) during the impingement examination and those that were not. Conclusion: These female athletes had a lower prevalence of radiographic FAI deformities compared with previously reported values for male athletes and a higher prevalence of acetabular dysplasia than reported for women in previous studies.

Accuracy and Feasibility of Dual Fluoroscopy and Model-Based Tracking to Quantify In Vivo Hip Kinematics During Clinical Exams

Accurate measurements of in-vivo hip kinematics may elucidate the mechanisms responsible for impaired function and chondrolabral damage in hips with femoroacetabular impingement (FAI). The objectives of this study were to quantify the accuracy and demonstrate the feasibility of using dual fluoroscopy to measure in-vivo hip kinematics during clinical exams used in the assessment of FAI. Steel beads were implanted into the pelvis and femur of two cadavers. Specimens were imaged under dual fluoroscopy during the impingement exam, FABER test, and rotational profile. Bead locations measured with model-based tracking were compared with those measured using dynamic radiostereometric analysis. Error was quantified by bias and precision, defined as the average and standard deviation of the differences between tracking methods, respectively. A normal male volunteer was also imaged during clinical exams. Bias and precision along a single axis did not exceed 0.17 and 0.21 mm, respectively. Comparing kinematics, positional error was less than 0.48 mm and rotational error was less than 0.58°. For the volunteer, kinematics were reported as joint angles and bone-bone distance. These results demonstrate that dual fluoroscopy and model-based tracking can accurately measure hip kinematics in living subjects during clinical exams of the hip.

Psychological Distress in Hip Arthroscopy Patients Affects Postoperative Pain Control

PURPOSE To determine whether patients with higher levels of preoperative psychological distress more frequently use a postoperative fascia iliaca nerve block for pain control after hip arthroscopy, and to determine whether a fascia iliaca nerve block is an effective adjunct to multimodal oral and intravenous analgesia after hip arthroscopy. METHODS One hundred seven patients undergoing hip arthroscopy were prospectively enrolled. Before surgery, patients were administered the Distress Risk Assessment Method questionnaire to quantify their level of preoperative psychological distress. Postoperatively, patients with pain inadequately controlled by multimodal oral and intravenous analgesics could request and receive a fascia iliaca nerve block. Pain scores, opioid consumption, time in the post-anesthesia care unit (PACU), and postoperative complications were recorded for all patients. RESULTS Patients with normal Distress Risk Assessment Method scores requested fascia iliaca nerve blocks approximately half as frequently (18 of 50 [36%]) as patients in the at-risk category (28 of 47 [60%]) or distressed category (7 of 10 [70%]) (P = .02). Patients with high levels of distress also received 40% more intraoperative opioid than patients with normal scores (P = .04). In the study population as a whole, patients who received a fascia iliaca nerve block (n = 53) had a higher initial visual analog scale (VAS) pain score in the PACU (7.2 ± 0.3 v 5.5 ± 0.4, P = .001) and showed greater improvement in the VAS pain score by PACU discharge (-4.3 ± 0.2 v -2.1 ± 0.3, P ≤ .0001) compared with patients who did not receive a block (n = 54). CONCLUSIONS Patients with higher levels of preoperative psychological distress more frequently requested a postoperative nerve block to achieve adequate pain control after hip arthroscopy. Patients receiving a block had greater improvement in VAS pain scores compared with patients managed with oral and intravenous analgesics alone. LEVEL OF EVIDENCE Level IV, case series.