Radiographic risk factors for labral lesions in femoroacetabular impingement

Expression of Acetabular Labral Vascular Endothelial Growth Factor and Nerve Growth Factor Is Directly Associated with Hip Osteoarthritis Pain: Investigation by Immunohistochemical Staining

The acetabular labrum enhances hip joint stability and plays a key role in osteoarthritis (OA) progression. Labral nerve endings contribute to hip OA pain. Moreover, vascular endothelial growth factor (VEGF) and nerve growth factor (NGF) are associated with pain. Consequently, we analysed VEGF and NGF expression levels in the labrum and their roles in OA. Labra obtained from OA patients were stained immunohistochemically, and labral cells were cultured and subjected to a reverse transcription (RT)-polymerase chain reaction (PCR) to analyse VEGF and NGF mRNA expression. VEGF and NGF expression were compared in each region of the labrum. Correlations between VEGF and NGF expression and age, body mass index, Kellgren-Lawrence grade, Harris Hip Score, the visual analogue scale (VAS), and Krenn score were analysed, and the RT-PCR confirmed the findings. VEGF and NGF expression were high on the labral articular side, negatively correlated with the Krenn score, and positively correlated with the VAS in early OA. VEGF and NGF mRNA expression increased significantly in patients with severe pain and decreased significantly in severely degenerated labra. In early OA, VEGF and NGF expression in the acetabular labrum was associated with the occurrence of hip pain; therefore, these factors could be effective targets for pain management.

Preoperative Alpha Angles Can Predict Severity of Acetabular Rim Chondral Damage in Symptomatic Cam-Type Femoroacetabular Impingement: A Prospective Observatory Study

PURPOSE

To identify the relationship between the alpha angle and the severity of chondrolabral separation as well as acetabular rim chondral damage in symptomatic cam-type femoroacetabular impingement (FAI) with or without focal pincer-type FAI.

METHODS

Patients who received hip arthroscopy under the diagnosis of symptomatic cam-type FAI between January 2018 and August 2018 were identified in a prospectively collected database. Patients were excluded if preoperative lateral center-edge angle <25°, lateral center-edge angle ≥40°, Tönnis grade >1, with previous surgery on the affected hip, or with concomitant synovial disease. The chondrolabral junction was classified into intact chondrolabral junction, stable chondrolabral separation and unstable chondrolabral separation. The classification of acetabular rim chondral damage was modified from the MAHORN (Multicenter Arthroscopy of the Hip Outcomes Research Network) classification: normal/softening, bubble, pocket, flap, and exposed bone. The relationship between the hip morphology and severity of chondrolabral junction and acetabular rim chondral damage was assessed.

RESULTS

A total of 71 patients with the mean age of 33.2 ± 11.0 years were included. Preoperative alpha angles on anteroposterior (AP) or Lauenstein view positively correlated with the severity of acetabular rim chondral damage (P = .028 and P = .016, respectively). A significant increment of the alpha angle between 2 consecutive grades of acetabular rim chondral damage was 7.1° (P = .001) on AP view and 5.2° on Lauenstein view (P = .001). The cut-off values for predicting advanced acetabular rim chondral damage (pocket, flap or bony exposure) were an AP alpha angle of 70° (P = .025) and a Lauenstein alpha angle of 57° (P = .003). There was no significant association between the alpha angle and the severity of chondrolabral separation.

CONCLUSIONS

In patients with symptomatic cam-type FAI with or without focal pincer-type FAI, greater preoperative alpha angles on AP and Lauenstein views can predict more severe acetabular chondral damage.

LEVEL OF EVIDENCE

Level III.

Editorial Commentary: Femoroplasty May Not Be Necessary in All Patients With Hip Femoroacetabular Impingement, But Cam Lesions Should Not Be Ignored in Patients With Significant Femoral Head-Neck Offset

Our knowledge of appropriate arthroscopic management of femoroacetabular impingement (FAI) continues to evolve. However, few studies exist evaluating mid- to long-term surgical outcomes to guide optimal treatment. The recent focus has been on the importance of cam femoroplasty in addition to labral treatment; however, studies have shown that correction of the alpha angle to normal does not correlate with patient outcomes. Furthermore, in cases of mixed impingement, an optimal degree of acetabuloplasty as measured by the lateral center-edge angle has not been determined. Few studies have evaluated isolated pincer decompression with omission of cam treatment. In select patients with small or negligible cam lesions who do not have acetabular dysplasia, a small, isolated acetabular rim resection of 1 to 3 mm may provide adequate FAI decompression as well as reduce surgical time and complications. Nonetheless, individualized FAI treatment is necessary that includes a comprehensive 180° femoroplasty in patients with sizable cam lesions to prevent future labral and chondral damage. An intraoperative dynamic examination is important to determine sufficient resolution of FAI. Predictive modeling may play an increasingly important role to ensure appropriate bony resection and to optimize long-term patient outcomes.

Biomechanical comparison of knotless vs. knotted suture anchors in the acetabular rim with respect to bone density

BACKGROUND

Acetabular labral tears are managed with suture anchors providing good clinical outcomes. Knotless anchors are easier to use and have a quicker insertion time compared to knotted anchors. The purpose of this study was to compare the biomechanical behavior of two different anchor designs (knotted vs. knotless) in ultimate load testing in correlation with bone density in the acetabular rim.

METHODS

Eighteen knotted Bio-FASTak and seventeen knotless PushLock anchors (both: Arthrex Inc., Naples, FL, USA) were inserted in the rims of two human acetabula, with known bone density distribution. The anchors were subjected to load-to-failure tests. Anchors were additionally tested in solid polyurethane foam with defined densities.

FINDINGS

The Bio-FASTak group showed higher survival rates at 1, 2, and 3 mm displacement and was able to withstand significantly higher loads at 3 mm displacement (p = 0.031). There was no statistically significant difference in stiffness (p = 0.087), yield- (p = 0.190), and ultimate load (p = 0.222) between the two groups. Only the PushLock group showed correlation between bone volume over total volume (BV/TV) and stiffness (R = 0.750, p = 0.086) and between BV/TV and yield load (R = 0.838, p = 0.037). Experiments on solid polyurethane foam confirmed the correlation between the mechanical properties and tissue density for the same anchor.

INTERPRETATION

PushLock shows similar biomechanical properties to the Bio-FASTak, but eliminates knot tying and potentially abrasive knots. In addition, biomechanical properties of the PushLock are governed by local bone density.

Assessment of Acetabular Morphology Using the Acetabular Anterior Center-Edge Angle on Modified False-Profile Radiographs

PURPOSE

To compare radiographic parameters of acetabular morphology between standard and modified false-profile (FP) radiographs.

METHODS

Standard and modified FP radiographs were obtained in 225 hips in 200 consecutive patients evaluated for hip pain and suspected femoroacetabular impingement. Radiographs were retrospectively reviewed by 2 readers to determine the anterior center-edge angle (ACEA), as assessed to the sourcil and to the bone edge. Inter-rater reliability of radiographic measurements was assessed using the intraclass correlation coefficient. Measurements were evaluated for normality with the Shapiro-Wilk test, averaged between the 2 readers, and compared between views using the paired Wilcoxon test.

RESULTS

The intraclass correlation coefficient values for standard and modified FP views were 0.923 and 0.932, respectively, measuring to the sourcil and 0.867 and 0.896, respectively, measuring to the lateral bone edge. The median difference in ACEA measurements to the sourcil was 1° between the standard and modified FP view (45° vs 44°, P < .001). The median difference in ACEA measurements to the bone edge was 2° (34° vs 32°, P < .001).

CONCLUSIONS

Thirty-five degrees of femoral internal rotation for a modified FP hip radiographic view provides similar clinical information regarding acetabular morphology to that of the standard FP view. Given that the modified FP view also provides better visualization of the anterosuperior head-neck junction cam lesion, the modified FP view may be preferred over the standard FP view in evaluation of hip pain in the young patient.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Postoperative alpha angle not associated with patient-centered midterm outcomes following hip arthroscopy for FAI

PURPOSE

The most commonly used parameter for defining cam-type femoroacetabular impingement(FAI) has been the alpha angle. The purpose of this study was to determine if patient-reported outcomes 5 years following hip arthroscopy for FAI were associated with postoperative alpha angle. We hypothesized that patient-reported outcomes would not be influenced by postoperative alpha angle in patients with FAI.

METHODS

230 patients had primary hip arthroscopy for FAI and chondrolabral dysfunction. The median age was 40 years (range 18-69). All patients had preoperative and 1 day postoperative alpha angles recorded. At minimum 5 years following arthroscopy, all patients completed an online questionnaire that included the modified Harris Hip score(MHHS), WOMAC, HOS ADL, HOS Sport, SF12 and patient satisfaction. This study was IRB approved. Patients were grouped into two, based on their postoperative alpha angle: <55° (n = 158) and ≥ 55° (n = 56).

RESULTS

The median preoperative alpha angle was 72° (range 50°-105°) and the median postoperative alpha angle was 45° (range 30°-100°). The postoperative alpha angle did not correlate with any outcome measure. The median preoperative alpha angle in the < 55° group was 71° and in ≥ 55° group the median was 74° (p = 0.044). The median follow-up was 5.1 years (range 5-7). The median mHHS was 85 (range 47-100) in the < 55° and 85 (range 54-100) in the ≥ 55° group (n.s); WOMAC was 5 (range 0-73) in the < 55° and 4.5 (range 1-57) in the ≥ 55° group(n.s); HOS ADL was 95 (range 31-100) in the < 55° and 96 (range 50-100) in the ≥ 55° group (n.s); HOS Sport was 88 (range 0-100) in the < 55° and 88 (range 13-100) in the ≥ 55° group (n.s) Median patient satisfaction was 9 (range 1-10) in both groups.

CONCLUSION

This study shows no statistically significant differences between the investigated patient-reported outcome scores at a 5 years postoperatively in relation to a correction of the alpha angle to 55°. While alpha angle has been shown to be an excellent preoperative diagnostic tool, the postoperative angle does not correlate with midterm outcomes or the development of osteoarthritis based on patient symptoms. The amount of osteoplasty should be based on dynamic examination at arthroscopy, and not by alpha angle.

LEVEL OF EVIDENCE

III Case-control, retrospective comparative study.

Risk Factors for Bilateral Femoroacetabular Impingement Syndrome Requiring Surgery

Purpose:

To identify the risk factors for contralateral surgery in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

Methods:

Patients who underwent unilateral surgery were compared with those who underwent staged bilateral surgery to identify risk factors associated with bilateral surgery. Variables examined included demographics, comorbidities, and radiographic features. Binary logistic regression was used to identify predictors of bilateral FAIS.

Results:

A total of 694 patients with an average age of 34.0 ± 13.1 years met were included in the analysis. Overall, 109 patients (15.3%) had staged bilateral hip arthroscopy for FAIS. Risk factors associated for bilateral FAIS requiring surgery were decreased age and lower Charlson Comorbidity Index (CCI). Compared with patients aged <25 years, those aged 25 to 34 years (odds ratio [OR], 0.5; P = 0.031), 35 to 44 years (OR, 0.5; P = 0.034), and ≥45 years (OR, 0.3; P = 0.002) had lower odds of bilateral labral tear. In addition, patients with a CCI <2 were three times more likely to require bilateral FAIS surgery (OR, 3.4; P = 0.044). None of the radiographic parameters predicted bilateral labral tears.

Conclusion:

Patients younger than 25 years and those with a CCI <2 had markedly increased rates of bilateral FAIS necessitating surgery compared with older patients. This study may be of value in preoperative counseling.

Differences in Hip Joint Biomechanics and Muscle Activation in Individuals With Femoroacetabular Impingement Compared With Healthy, Asymptomatic Individuals: Is Level-Ground Gait Analysis Enough?

Background:

Femoroacetabular impingement (FAI) is a recognized cause of hip and groin pain and a significant factor in hip joint function during sport. Objective tests for understanding hip function are lacking in this population.

Purpose:

To determine whether biomechanical and electromyographic features of hip function during level-ground walking differ between a group diagnosed with FAI and those with no symptoms of FAI.

Study Design:

Controlled laboratory study.

Methods:

A total of 20 asymptomatic individuals and 20 individuals with FAI walked on a dual-belt instrumented treadmill at self-selected walking velocities. Sagittal and frontal plane joint motions, moments, and muscle activation for the gluteus medius, gluteus maximus, rectus femoris, and medial and lateral hamstrings were analyzed. Discrete measures were extracted from each biomechanical waveform, and principal component analysis was used to determine hip joint muscle activation and hip adduction moment patterns. Statistical significance was determined by use of Student t tests with Bonferroni adjustments for multiple comparisons (α = .05).

Results:

Individuals with FAI walked more slowly (P = .015) and had lower self-reported function (P < .001). No differences in muscle strength were found between the symptomatic and contralateral legs in the FAI group (P > .017), but those with FAI had lower strength in the knee extensors and flexors and the hip extensors, flexors, and adductors compared with the asymptomatic group (P < .017). Individuals with unilateral symptomatic FAI walked with similar biomechanical and hip muscle electromyographic results bilaterally. The only differences found were a greater amplitude of gluteus maximus activation in the FAI symptomatic leg compared with the asymptomatic group and greater medial hamstring activation than lateral hamstring activation in the FAI group in both limbs compared with the asymptomatic group.

Conclusion:

Individuals with FAI were generally deconditioned and reported significantly more functional limitations. No biomechanical differences existed between groups during level walking, yet hamstring and gluteus maximus activation differed when the symptomatic group was compared with the asymptomatic group.

Clinical Relevance:

The field lacks objective testing of hip joint function to understand implications of FAI for dynamic movements, particularly with applications to biomechanics and electromyography. Level walking was of limited value for understanding FAI hip function, and the development of a more challenging gait assessment is warranted.

Radiographic predictors of femoroacetabular impingement treatment outcomes

PURPOSE

To review the literature on femoroacetabular impingement (FAI) treatment outcomes, specifically focusing on potential pre-operative radiographic parameters that may provide prognostic information regarding outcomes following surgical management.

METHODS

A comprehensive review of computerized literature databases (Medline Ovid and PubMed) was performed, searching for articles reporting on FAI treatment outcomes. A single reviewer screened titles, abstracts and performed full-text reviews of eligible studies. The references of these studies were further screened for additional potentially relevant studies. A total of 243 studies were reviewed, with 18 meeting inclusion criteria.

RESULTS

Thirteen arthroscopic studies reported on 1556 patients, with clinical improvement in 35-92 % of patients and associated failure rates of 12-71 %. Five open surgical studies reported on 238 patients with clinical improvement in 65-95 % of patients and associated failure rates of 0-35 %. Both arthroscopic and open studies identified inferior outcomes with pre-operative radiographic findings of an elevated Tönnis grade (grade 2 or higher), joint space <2 mm, lateral centre-edge angle (LCEA) <20° and incomplete femoral osteoplasty.

CONCLUSION

Pre-operative radiographic findings of osteoarthritis (Tönnis grade 2/3, <2 mm joint space) or dysplasia (LCEA < 20°) should be considered relative contraindications to joint preservation surgery as outcomes are worse among these patients and associated with a higher risk of conversion to total hip arthroplasty. Care should also be taken to perform a thorough femoral osteoplasty to reduce the risk of failure and need for revision surgery.

LEVEL OF EVIDENCE

III.

Magnetic resonance arthrography and the prevalence of acetabular labral tears in patients 50 years of age and older

OBJECTIVE

Arthroscopy for acetabular labral tears has minimal impact on pain and function in older patients, especially in the setting of concomitant osteoarthritis. Still, many physicians seek this diagnosis with MR arthrography. Our purpose is to assess the frequency of acetabular labral tears in older patients with hip pain and correlate likelihood of labral pathology with severity of osteoarthritis as visualized on conventional radiograph.

MATERIALS AND METHODS

From 2004 to 2013, 208 hip MRI arthrograms and corresponding radiographs on patients aged 50 years and older were identified. Age, gender, grade and location of labral tear, alpha angle, Tönnis grade, and joint space width were documented. Labral tears and alpha angle were identified and measured on MR arthrogram. Tönnis grade and joint space width were measured on radiographs.

RESULTS AND CONCLUSIONS

On MR arthrography, true labral tearing was identified in 73 % of patients. There was some degree of labral pathology in 93.3 % of patients, and this increased to 100 % in patients with moderate to severe osteoarthritis, as defined by Tönnis grade 2-3 or joint space width ≤ 2 mm. There were no statistically significant correlations between labral tear grade and Tönnis grade or joint space width. Given the high frequency of labral pathology and the questionable efficacy of arthroscopic surgical intervention in older patients, MR arthrography should be primarily for those with minimal arthritis on radiograph and potential to benefit from surgery. If further imaging beyond radiographs is necessary in these patients, standard MRI may be a more appropriate imaging tool.

Quantitative magnetic resonance arthrography in patients with femoroacetabular impingement

PURPOSE

Quantitative MRI (QMRI) of the hip with sequences such as T1_ρ and T2 mapping has been utilized to detect early changes in cartilage matrix composition. However, QMRI has not been performed in the presence of intra-articular contrast. Thus the purpose of this study was to evaluate the feasibility and use of QMRI during MR-arthrography (MRA) in femoracetabular impingement (FAI) patients.

MATERIALS AND METHODS

Using a 3 Tesla MR-scanner, 10 FAI patients underwent a unilateral MRA and standard MRI of the hip joint. Global and sub-regional T1_ρ and T2 relaxation times of the acetabular and femoral articular cartilage were computed in the MRA and MRI assessments and agreement of these values were assessed using the Krippendorff's alpha (α) coefficient and linear regression (μ). T1_ρ and T2 relaxation times between the MRA and MRI were compared using a repeated measures analysis of variance.

RESULTS

Both global and sub-regional T1_ρ and T2 relaxation times demonstrated strong agreement (α > 0.83; μ > 0.85) independent of intra-articular contrast. Also, global and sub-regional acetabular T1_ρ (P = 0.72) and T2 (P = 0.94), as well as femoral T1_ρ , relaxation times were similar between MRA and MRI (P = 0.73) yet femoral T2 relaxation times decreased when using intra-articular contrast (P = 0.04).

CONCLUSION

This study demonstrated the feasibility of T1ρ and T2 mapping for use in hip MRA with FAI patients. The inclusion of QMRI in MRA provides a quantitative assessment of the effects of FAI on hip joint articular cartilage while allowing for detailed assessment of labral pathology with the use of intra-articular contrast. J. Magn. Reson. Imaging 2016;44:1539-1545.

Prevalence of acetabular labral tears in asymptomatic children

PURPOSE

Magnetic resonance imaging (MRI) is a sensitive, non-invasive modality to diagnose acetabular labral pathology, and the normal variants of the acetabular labrum have been characterized in adults. However, the prevalence of labral pathology in the asymptomatic pediatric population is unknown.

METHODS

All pelvic MRIs performed at a large tertiary-care children's hospital were reviewed during one calendar year (2014). Only patients aged between 2 and 18 years were included, and scans were excluded for hip pain/pathology or technical inadequacy. A blinded pediatric musculoskeletal radiologist read all eligible scans for the presence or absence of a labral tear.

RESULTS

Three hundred and ninety-four pelvic MRIs were screened, and patients were excluded for hip pain/pathology (85 subjects), or technical inadequacy (190 subjects). One hundred and eight subjects (216 hips) met the inclusion criteria and were technically adequate for analysis. Labral tears were visualized in three of 216 (1.4 %) hips (two of the 110 subjects; 1.9 %).

CONCLUSIONS

There is a low rate of asymptomatic labral pathology by MRI in pediatric patients. The clinical history remains the means of differentiating real labral pathology from spurious imaging findings.

LEVEL OF EVIDENCE IV

Case series (prevalence).

Inclusion and Exclusion Criteria in the Diagnosis of Femoroacetabular Impingement

PURPOSE

The purpose of this study was to clarify the criteria for femoroacetabular impingement (FAI) by way of a systematic review of FAI-related articles, as well as to define more appropriate inclusion or exclusion criteria in the diagnosis of FAI.

METHODS

A systematic review of FAI-related articles was performed using Web of Science. Thirty-two articles met the inclusion and exclusion criteria. In these articles we investigated radiographic findings for the diagnosis of FAI and the prevalence of each FAI-related finding.

RESULTS

The crossover sign was used in 22 articles (69%); acetabular index, 9 articles (28%); posterior wall sign, 7 articles (22%); and prominence of the ischial spine sign, 3 articles (7%). Regarding acetabular coverage, the lateral center-edge (LCE) angle was described in 13 articles (41%), in which an LCE angle either of more than 40° or of more than 30° combined with an acetabular index of less than 0° was considered an inclusion criterion for pincer impingement. Meanwhile, the alpha angle was used in 28 articles (88%), in which 50° or 55° was recommended as a positive finding of cam impingement.

CONCLUSIONS

Common findings of pincer or cam deformity were used to select FAI patients with sufficient coverage of the acetabulum with an LCE angle of more than 25°. Patients with an LCE angle of less than 25° or those with local acetabular deficiency regardless of having a normal LCE angle should be excluded from the FAI criteria, even if the FAI-related findings are positive.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I through IV studies.

Discrepancies in measuring acetabular coverage: revisiting the anterior and lateral center edge angles

The lateral center edge angle (LCEA) and the anterior center edge angle (ACEA) are commonly used to assess acetabular coverage of the femoral head. There are two distinct methods found in the literature to obtain these angles, specifically, measuring to the most lateral bone edge versus the sclerotic lateral sourcil edge. A difference between these two methods may contribute to inconsistent estimates of acetabular coverage, and potentially lead to clinical misdiagnosis and treatment mismanagement. The objectives of this study were to quantify the difference between bone edge and sourcil edge measurements and to determine how the difference influences the classification of acetabular coverage in adult patients with suspected hip pathomorphology. Two observers completed the measurements independently using preoperative anteroposterior and false profile radiographs. Bland-Altman plots and paired t-tests were used to compare measurement methods. Bone and sourcil measurements of the LCEA and ACEA were significantly different (both P < 0.001). On average, the bone LCEA was 4° (95% limits of agreement = -2° to 10°) greater than the sourcil LCEA. The bone ACEA was, on average, 10° (95% limit of agreement = -2° to 22°) greater than the sourcil ACEA. The differences often led to different clinical classifications for the same hip. With a statistically and clinically significant difference in the quantification of acetabular coverage using bone edge versus sourcil edge methods for measuring the LCEA and ACEA in adult patients, it should be mandatory to clearly identify which method was used in each study.

Femoroacetabular impingement surgery: are we moving too fast and too far beyond the evidence?

Femoroacetabuler impingement (FAI) is becoming increasingly recognised as a potential pathological entity for individuals with hip pain. Surgery described to correct FAI has risen exponentially in the past 10 years with the use of hip arthroscopy. Unfortunately, the strength of evidence supporting both the examination and treatment of FAI does not appear to accommodate this exponential growth. In fact, the direction currently taken for FAI is similar to previously described paths of other orthopaedic and sports medicine pathologies (eg, shoulder impingement, knee meniscus tear) for which we have learned valuable lessons. The time has come for improved terminology, study design, and focus on delineation of successful treatment variables in the interest of those individuals with clinical indications of FAI so that we can appropriately address their needs.

Labral injury: radiographic predictors at the time of hip arthroscopy

PURPOSE

The purpose of this study was to investigate the influence of multiple demographic and radiographic findings on the size of labral tears identified at the time of hip arthroscopy.

METHODS

Data were prospectively collected for patients treated with arthroscopic labral repair or debridement from February 2008 to August 2011. Preoperative radiographic and demographic data were collected for 392 patients during the study period. Exclusion criteria included revision surgery and previous hip conditions. An anteroposterior pelvic view, 45° Dunn view, and false-profile view were used to measure Tönnis grade, neck-shaft angle, alpha angle, lateral center edge angle (LCEA), anterior center edge angle (ACEA), acetabular inclination, and the extent of crossover sign when present. At the time of surgery, labral tear size and location were documented for all patients, using traditional acetabular clock face nomenclature for sizing. A multiple linear regression analysis was then performed to assess the correlation of radiographic and demographic findings with the size of the labral tear.

RESULTS

Regression analysis displayed statistical significance for sex (P < .0001), age (P < .0001), and alpha angle (P = .005) with labral tear size. For female patients, Tönnis grade (P = .0004) and neck-shaft angle (P = .004) correlated with labral tear size. This model accounted for only 26% of variation in labral tear size.

CONCLUSIONS

Preoperative risk factors for the extent of labral tear size are male sex, increasing age, and increasing alpha angle. Labral tears were larger in female patients with higher Tönnis grades and lower neck-shaft angles. Measurements of acetabular coverage and version showed no correlation with labral tear size. The majority of labral tear size variation was not accounted for in this model.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Magnetic resonance imaging of the hip: poor cost utility for treatment of adult patients with hip pain

BACKGROUND

Although MRI is frequently used to diagnose conditions affecting the hip, its cost-effectiveness has not been defined.

QUESTIONS/PURPOSES

We performed this retrospective study to determine for patients 40 to 80 years old: (1) the differences in hip MRI indications between orthopaedic and nonorthopaedic practitioners; (2) the clinical indications that most commonly influence treatment decisions; (3) the likelihood that hip MRI influences treatment decisions separate from plain radiographs; and (4) the cost of obtaining hip MRI studies that influence treatment decisions (impact studies).

METHODS

We retrospectively assessed 218 consecutive hip MRI studies (213 patients) at one institution over a 5-year interval. Medical records, plain radiographs, and MRI studies were reviewed to determine how frequently individual MRI findings determined treatment recommendations (impact study). The cost estimate of an impact study was calculated from the product of institutional MRI unit cost (USD 436) and the proportion of impact studies relative to all studies obtained either for a specific indication or by an orthopaedic/nonorthopaedic clinician.

RESULTS

Nonorthopaedic clinicians more frequently ordered hip MRI without a clinical diagnosis (72% versus 30%, p < 0.01), before plain radiographs (29% versus 3%, p < 0.001), and with less frequent impact on treatment (6% versus 15%, p < 0.05). Hip MRI most frequently influenced treatment when assessing for a tumor (58%, p < 0.001) or infection (40%, p < 0.001) and least frequently when assessing for pain (1%, p < 0.002). Hip MRI impacted a treatment decision independent of plain radiographic findings in only 7% of studies (3% surgical, 4% nonsurgical). Hip MRI cost was least when assessing for a neoplasm (USD 750) and greatest when assessing undefined hip pain (USD 59,000). The cost of obtaining an impact study was also less when the ordering clinician was an orthopaedic clinician (USD 2800) than a nonorthopaedic clinician (USD 7800).

CONCLUSIONS

Although MRI can be valuable for diagnosing or staging specific conditions, it is not cost-effective as a screening tool for hip pain that is not supported by history, clinical examination, and plain radiographic findings in patients between 40 and 80 years of age.

LEVEL OF EVIDENCE

Level IV, economic and decision analysis study. See Instructions for Authors for a complete description of levels of evidence.

Clinical and morphologic factors associated with suture anchor refixation of labral tears in the hip

BACKGROUND

The acetabular labrum is critical to hip function. Surgical options for treatment of a damaged labrum include removal, debridement, and refixation using suture anchors.

QUESTIONS/PURPOSES

The purpose of this study is to determine if certain patient demographic and osseous morphological factors result in increased labral damage requiring refixation.

METHODS

Data was collected prospectively from a consecutive series of 334 procedures performed from August 2010 to June 2011 for femoroacetabular impingement. Demographic data, including age, sex, and race, was collected from patient charts. Three-dimensional (3D) CT scans were reviewed to retrieve alpha angles, acetabular version, femoral version, and lateral center edge angle on the symptomatic hip.

RESULTS

In 238 (71.3%) of the procedures, the labrum required refixation using suture anchors with a mean of 2.74 anchors being used. Of males, 78.8% required suture anchors and 62.3% of females required suture anchors. Among procedures requiring suture anchors, significantly more suture anchors were used in males (2.92) than females (2.47). Regression analysis showed a positive association between alpha angle, acetabular retroversion at 1 and 2 o'clock, and the number of suture anchors used. The mean alpha angle in the cohort that required suture anchors (63.1°) was significantly greater than the cohort that did not (59.4°).

CONCLUSION

This study found femoral deformities to contribute more to labral damage than acetabular deformities and highlighted the importance of preoperative 3D CT scans. This study provides demographic and morphologic factors to review preoperatively to evaluate if extensive labral damage is present and if suture anchor refixation will be required.

Cam lesion femoral osteoplasty: in vitro biomechanical evaluation of iatrogenic femoral cortical notching and risk of neck fracture

PURPOSE

To investigate the effect of femoral cortical notching at different depths on the peak compressive load and energy required to cause a femoral neck fracture in composite femurs.

METHODS

Thirty fourth-generation composite femurs were divided into 5 groups: (1) intact with an inherent alpha angle of 61°, (2) resection of inherent cam lesion by reducing the alpha angle from 61° to 45°, (3) cam resection and cortical notching of a 5.5-mm spherical diameter by 2.00-mm (grade I) depth, (4) cam resection with cortical notching of 4.00-mm (grade II) depth, and (5) cam resection with cortical notching of 6.00-mm (grade III) depth. The specimens were loaded in the position of midstance during gait and tested until failure using a dynamic tensile testing machine at a rate of 6 mm/min.

RESULTS

Grade II and grade III cortical notching depths with cam resections resulted in a significant decrease in the ultimate load to failure and energy (P < .05) compared with the intact state. The grade II and grade III cortical notching groups with cam resection failed at a significantly lower ultimate load and with significantly lower energy when compared with the cam resection group alone.

CONCLUSIONS

The findings of this study demonstrated significant decreases in ultimate load and energy to failure between the intact group and the grade II and grade III femoral cortical notching groups with cam resection.

CLINICAL RELEVANCE

Iatrogenic cortical notching may lead to an increased risk of postsurgical complications, specifically femoral neck fracture. Thus, surgical intervention for a cam lesion femoral osteoplasty should strive for precision, especially around the femoral neck.

The relevance of the radiological signs of acetabular retroversion among patients with femoroacetabular impingement

Orthopaedic surgeons have accepted various radiological signs to be representative of acetabular retroversion, which is the main characteristic of focal over-coverage in patients with femoroacetabular impingement (FAI). Using a validated method for radiological analysis, we assessed the relevance of these signs to predict intra-articular lesions in 93 patients undergoing surgery for FAI. A logistic regression model to predict chondral damage showed that an acetabular retroversion index (ARI) > 20%, a derivative of the well-known cross-over sign, was an independent predictor (p = 0.036). However, ARI was less significant than the Tönnis classification (p = 0.019) and age (p = 0.031) in the same model. ARI was unable to discriminate between grades of chondral lesions, while the type of cam lesion (p = 0.004) and age (p = 0.047) were able to. Other widely recognised signs of acetabular retroversion, such as the ischial spine sign, the posterior wall sign or the cross-over sign were irrelevant according to our analysis. Regardless of its secondary predictive role, an ARI > 20% appears to be the most clinically relevant radiological sign of acetabular retroversion in symptomatic patients with FAI.

Spontaneous hip labrum regrowth after initial surgical débridement

BACKGROUND

Anecdotal evidence from second-look hip arthroscopies and animal studies has suggested spontaneous labral regrowth may occur after débridement. However, these observations have not been systematically confirmed.

QUESTIONS/PURPOSES

We (1) determined whether labral regrowth occurs after débridement in human hips; (2) if so, described the characteristics of the reconstituted labrum; and (3) determined the association, if any, of age with the presence and quality of labral regrowth.

METHODS

We retrospectively reviewed all 24 patients who previously had open hip surgical dislocation with labral débridement for treatment of femoroacetabular impingement (FAI) and concomitant hip arthroscopy 2 years after index procedure in association with planned removal of trochanteric hardware between January and December 1999. Data recorded included amount of labral resection at the index procedure using the clockface method, presence and quality of any labral regrowth, presence of any labral scarring or inflammation, and WOMAC(®) scores. Minimum clinical followup was 11 years (average, 12 years; range, 11-12 years).

RESULTS

All patients demonstrated labral regrowth at arthroscopy at 2 years. Homogeneous regrowth of labral height was seen in 21 of 24 patients, with labral scarring noted in four of 24. Average WOMAC(®) score was 98 points (range, 90-100 points) at the time of hardware removal. Increasing patient age was independently associated with decreased WOMAC(®) score and inhomogeneous regrowth of the labrum.

CONCLUSIONS

Labral regrowth after resection was seen in all patients at 2 years from index operation. Increasing age, however, was associated with poorer quality of the reconstituted labrum.

Femoroacetabular impingement

Both arthroscopic and open operative treatment of femoroacetabular impingement (FAI) can reproducibly relieve hip pain with correction of the underlying osseous deformity and treatment of the associated labral pathology, particularly in patients without substantial articular cartilage injury at the time of surgery. Between 75% and 90% of athletes undergoing FAI surgery return to sports at their pre-injury level of function. There is no peer-reviewed evidence to date reporting on the efficacy of nonoperative treatment and return to play with FAI. Successful operative treatment of impingement requires appropriate and complete correction of the mechanical injury that led to the symptomatic labral pathology. Early intervention prior to the onset of irreversible chondral damage is critical to the long-term success of FAI surgery. Complex deformities involving combinations of static and dynamic mechanical factors often coexist, so careful preoperative evaluation of the underlying structural anatomy is critical to successful treatment planning.

Osteonecrosis and femoro-acetabular impingement: sequelae of developmental dysplasia of the hip

A 2-year-old girl with developmental dysplasia of the right hip underwent open reduction and capsulorrhaphy via the anterior approach with hip spica casting in an internally rotated position. During her 26 years of follow-up, she was found to have osteonecrosis and subsequently cam-type femoro-acetabular impingement at 28 years of age. She was treated with surgical dislocation of the hip and osteochondroplasty to recreate the normal contour of the head and neck offset.