Bilateral Hip Arthroscopy: Can Results From Initial Arthroscopy for Femoroacetabular Impingement Predict Future Contralateral Results?

PURPOSE

To determine the degree of correlation of radiographic measurements, degree of correlation of intraoperative pathology, and difference in outcomes between sides of patients requiring staged bilateral hip arthroscopy.

METHODS

Two high-volume hip preservation centers retrospectively reviewed hip preservation databases for staged bilateral hip arthroscopies conducted between 2008 and 2015. Patients were separated into those who presented with bilateral hip pain and those that presented with unilateral pain and developed contralateral pain >2 years later. Patients were analyzed for radiographic correlation (alpha angle, lateral center edge angle, anterior center edge angle, magnetic resonance imaging alpha angle, Tönnis grade) and correlation of intraoperative pathology (acetabular labrum articular disruption grade, Outerbridge grade/location, Villar class ligamentum teres tears, labral tear location, symmetry of Seldes tear types, and the differences between operative procedures). Patient-reported outcomes were analyzed (modified Harris Hip Score, Non-Arthritic Hip Score, International Hip Outcome Tool-12, hip outcome score-sport specific subscale, visual analog scale, patient satisfaction). Correlative tests included Pearson and Spearman; univariate and multivariate analysis for differences included χ-square test and Student t tests for ordinal and continuous variables respectively.

RESULTS

A total of 133 of 2,705 patients (4.6%) underwent bilateral hip arthroscopy. Radiographic alpha angle, magnetic resonance imaging alpha angle, lateral center edge angle, and anterior center edge angle demonstrated strong correlation (Pearson's coefficients 0.651, 0.648, 0.644, 0.667, respectively, P < .0001). Tönnis grade was weakly correlated (Pearson's coefficient 0.286, P = .001). Intraoperative pathology was moderately correlated (Pearson's coefficients for acetabular Outerbridge location, 0.300, P = .0170; acetabular labrum articular disruption, 0.490, P < .0001; acetabular Outerbridge; 0.530; P < .0001; femoral head Outerbridge, 0.459, P < .0001; Villar class, 0.393, P < .0001; and labral tear location, 0.468, P < .0001). Labral tear Seldes type was compared with Bowker's symmetry test and there was no significant difference between sides. There were no significant differences in surgical interventions performed between sides. Patients with bilateral hip arthroscopies significantly improved in all measured patient-reported outcomes and had a high patient satisfaction after both procedures. Final patient-reported outcomes and change in patient-reported outcomes were not different between procedures; follow up ranged from 3 months to 8 years.

CONCLUSIONS

This study demonstrated an incidence of 4.6% of patients who require bilateral hip arthroscopy. These patients can expect significant improvement after surgical intervention. Patients that had 1 side done gained similar improvement when the contralateral side was performed. Preoperative radiographic, intraoperative pathology, and procedures performed were similar between hips.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Hip Dysplasia Compromises the Outcome of Femoroacetabular Impingement Surgery

BACKGROUND

The optimal treatment for patients with symptomatic hip dysplasia presenting with labral tear is unknown. Although femoroacetabular osteoplasty (FAO) has excellent outcome for most femoroacetabular impingement patients, the presence of concomitant hip dysplasia has been implicated as an adverse prognostic factor. This study evaluated the outcome of FAO in a group of dysplastic hips and compared the outcome to a cohort of patients without dysplasia.

METHODS

Seventy-three patients (38 males, 35 females) with hip dysplasia who underwent FAO between 2007 and 2015 were identified. The minimum 2-year clinical, functional (modified Harris Hip Score and Short-Form 36 Health Survey), and radiological outcome was compared with 550 patients without dysplasia who underwent FAO by the same surgeon. The preoperative and postoperative alpha angle, Tonnis grade, joint space, and presence of chondral lesion were determined and compared. Conversion to total hip arthroplasty or revision FAO was considered as treatment failure.

RESULTS

The mean age in the dysplasia cohort was 30.7 ± 11.8 years compared to 34.5 ± 11.2 in the nondysplastic group. The mean follow-up was 4.3 years for dysplasia cohort and 4.1 for the nondysplastic group. The mean modified Harris Hip Score and Short-Form 36 Health Survey6 was significantly lower in the dysplastic group at 75.1 and 74.3 compared to 83.4 and 85.6 for the comparison group. There was a higher percentage of failure at 28.8% among dysplasia patients compared to 2.5% in the nondysplastic group.

CONCLUSION

Although labral repair and FAO may be an option for patients with hip dysplasia, the outcome in this population appears to be less optimal compared to femoroacetabular impingement patients with no evidence of dysplasia. Labral repair and osteoplasty should be limited to those with mild and borderline dysplasia.

Acetabular Chondral Lesions Associated With Femoroacetabular Impingement Treated by Autologous Matrix-Induced Chondrogenesis or Microfracture: A Comparative Study at 8-Year Follow-Up

PURPOSE

The aim of this retrospective study was to investigate, at 8 years, the clinical follow-up and failure rate (revision rate/conversion to arthroplasty) of patients with hip chondral lesions associated with femoroacetabular impingement and to compare over time the treatment by microfracture (MFx) and autologous matrix-induced chondrogenesis (AMIC).

METHODS

Patients aged between 18 and 55 years, with acetabular grade III and IV chondral lesions (Outerbridge), measuring 2 to 8 cm2 operated on at least 8 years before enrollment. Exclusion criteria were rheumatoid arthritis, dysplasia, or axial deviation of the femoral head. There were no arthritic lesions, Tonnis < 2, or joint space of at least 2 mm. MFx was performed with an awl, and the Chondro-Gide membrane used for the AMIC procedure was placed without glue. Outcomes used modified Harris hip score (mHHS) at 6 months and yearly for 8 years and patient acceptable symptomatic state.

RESULTS

Among 130 patients, 109 fulfilled inclusion criteria. Fifty were treated by MFx and 59 by AMIC. The mHHS significantly improved in both groups from 46 ± 6.0 to 78 ± 8.8 for mHHS at 6-12 months, even for lesions > 4 cm2. From 2 to 8 years, mHHS in the AMIC group was better than in the MFx group (P < .005). This mHHS improvement in the AMIC group was maintained through the 8-year follow-up period, whereas it deteriorated after 1 year in the MFx group (P < .005). Eleven patients (22%) in the MFx group required total hip arthroplasty (THA); none in the AMIC group did. Patient acceptable symptomatic state analysis confirmed similar short-term improvement, but a significant (P < .007) degradation after 2-8 years in MFx patients.

CONCLUSIONS

MFx and AMIC techniques led to marked clinical short-term improvement in patients with chondral defects resulting from femoroacetabular impingement in the first 2 years. However, AMIC gave significantly better results as measured by mHHS, which were maintained after 8 years, the results of MFx in the hip deteriorated over time with 22% of patients undergoing conversion to THA. No patient in the AMIC group was converted to THA; the results of AMIC appeared stable over time and independent of lesion size.

LEVEL OF EVIDENCE

III, retrospective patient group study.

Is There an Association Between Noncontact Anterior Cruciate Ligament Injuries and Decreased Hip Internal Rotation or Radiographic Femoroacetabular Impingement? A Systematic Review

PURPOSE

To perform a systematic review to determine if there is (1) an association between decreased hip internal rotation and anterior cruciate ligament (ACL) tear rates; (2) an association between radiographic femoroacetabular impingement (FAI) and ACL tear rates; and (3) biomechanical evidence demonstrating increased strain in the ACL of patients with decreased hip internal rotation.

METHODS

A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies investigating relationships between hip motion, hip radiographs, and ACL tear were sought. Studies with Levels of evidence I-IV were eligible for inclusion. Study methodology/evidence were evaluated using Methodological Index for Non-Randomized Studies (MINORS), Strengthening the Reporting of Observational Studies in Epidemiology (STROBE), and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria.

RESULTS

Eleven studies were analyzed (2 cadaveric in vitro models, 8 clinical studies measuring hip internal rotation (2 concurrently assessing radiographic FAI), and 1 clinical study assessing radiographic FAI alone). Mean MINORS, STROBE, and GRADE for the studies was 82.4%, 20.9 out of 22, and "low," respectively. A total of 959 subjects (84.8% male; mean age 23.6 ± 3.8 years) were analyzed. Overall, 378 subjects sustained 427 ACL tears (399 primary ACL ruptures, 28 reruptures). Six of 8 clinical studies identified a significant association between limited rotation (internal rotation [IR; loss greater than 10°-20°], external rotation [ER], or combined IR + ER [loss greater than 20°]) and ACL tears. Two studies found an association between ACL ruptures and radiographic cam/pincer impingement. Two cadaveric models found a significant association between ACL strain and limited hip internal rotation.

CONCLUSIONS

This systematic review identified a significant association between ACL tear and both limited hip rotation and radiographic FAI.

LEVEL OF EVIDENCE

Level IV, systematic review of Levels II-IV studies.

Gait deviations in transverse plane after SCFE in dependence on the femoral offset

Residual deformity of the femoral head after slipped capital femoral epiphysis (SCFE) may be accompanied by a loss of femoral offset and lead to femoro-acetabular impingement (FAI), especially during hip flexion. It is hypothesized that during phases of the gait cycle, when the hip is flexed, the offset-loss is compensated by an increased external rotation. The gait pattern of 36 patients suffering from SCFE, who were treated by pinning-in-situ, were compared to a control group of 40 healthy adults by an instrumented 3D-gait analysis. Total patient group was subdivided into 3 subgroups in dependence on the offset (offset groups (OG)) quantified by the angle α according to Nötzli: OG1: α-angle <55°, OG2: α-angle between 55 and 75°, OG3: α-angle >75°. Comparisons were made at 3 instants: initial foot contact (0% gait cycle (GC)), 40-60% GC and 90-100% GC. Patients showed an increased external hip rotation during all 3 periods of the GC with a tendency of increasing external rotation in association with offset-loss. Only during hip extension (40-60% GC) there was a weak correlation between angle α and hip rotation (r=-0.375, p=0.024). In conclusion, the offset-loss does not lead to a functional relevant impingement during walking which needs compensation strategies like increasing external rotation during periods of hip flexion.

What Are the Risk Factors for Revision Surgery After Hip Arthroscopy for Femoroacetabular Impingement at 7-year Followup?

BACKGROUND

In recent years, surgical treatment of symptomatic femoroacetabular impingement (FAI) has been increasingly performed using arthroscopy. Bony pathomorphologies and damage to the labrum as well as cartilage defects can be addressed with comparable results to open surgery with overall less surgery-related complications. Despite the increasing importance of hip arthroscopy, however, reports on midterm clinical and radiographic outcomes and comparison to open surgical hip dislocation are scarce.

QUESTIONS/PURPOSES

(1) What are the clinical and radiographic outcomes at a mean 7-year followup; (2) what is the cumulative 7-year survivorship, using the endpoints of THA, progression of osteoarthritis according to Tönnis, or poor clinical outcome with a Merle d'Aubigné score of less than 15 points, of hips with symptomatic FAI treated arthroscopically; and (3) what factors were associated with revision surgery?

METHODS

Between 2003 and 2008 we performed a total of 62 arthroscopic procedures (60 patients) for FAI. For the same indication, we also performed 571 surgical hip dislocations during that time. Standardized treatment was femoral offset correction, acetabular rim trimming, or both and treatment of labral or chondral defects. An arthroscopic approach was generally used if the pathomorphology was located in the anterosuperior quadrant of the hip and was gradually used for more complex cases. We excluded 10 hips (10 patients) in which the standardized treatment was not achieved and no offset correction or acetabular rim trimming was performed. Of the remaining 52 hips (50 patients), 39 hips underwent isolated femoral offset correction, four hips isolated acetabular rim trimming, and nine hips both procedures. At a mean followup of 7 years (range, 5-11 years), the Merle d'Aubigné clinical score was obtained and plain radiographs were examined (Tönnis grade, heterotopic ossification, lateral center-edge [LCE] angle, acetabular index [AI], extrusion index, alpha angle, and pistol grip deformity). Cumulative survivorship was calculated according to Kaplan-Meier using conversion to THA, progression of osteoarthritis (one or more Tönnis grades), or poor clinical outcome (Merle d'Aubigné score < 15 points) as endpoints. Cox regression analysis was used to identify univariate factors associated with revision surgery.

RESULTS

At last followup we detected a significant but possibly not clinically relevant increase in Merle d'Aubigné scores from preoperative levels to latest followup (14 ± 1 versus 16 ± 2, mean difference 2 points with a 95% confidence interval [95% CI] -3 to 7, p < 0.001). Six hips showed progression of osteoarthritis. Cumulative survivorship (hips free from conversion to THA, progression of osteoarthritis, or poor clinical outcome) of hips treated with hip arthroscopy for FAI at a mean followup of 7 years was 81% (95% CI, 68%-95%). Two patients (two hips, 4%) underwent THA at 7 and 9 years, respectively. An increased preoperative acetabular coverage (LCE angle, AI), increased offset in the superior portion of the femoral neck (pistol grip deformity), and a remaining pistol grip deformity postoperatively were associated with revision surgery. Any treatment of the labrum did not influence the outcome. Factors associated with failure could not be identified.

CONCLUSIONS

In this series of patients with arthroscopic treatment of symptomatic FAI, hip arthroscopy resulted in an intact hip without progression of osteoarthritis and with a Merle d'Aubigné score of ≥ 15 points in 81% of patients at 7-year followup. Increased acetabular coverage and femoral pistol grip deformity were risk factors for revision surgery.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Poorer Arthroscopic Outcomes of Mild Dysplasia With Cam Femoroacetabular Impingement Versus Mixed Femoroacetabular Impingement in Absence of Capsular Repair

PURPOSE

To compare outcomes of mild dysplasia with cam femoroacetabular impingement (FAI) vs mixed FAI with hip arthroscopy without capsular repair.

METHODS

A retrospective review of a 2009 to 2010 multicenter prospective outcome study was performed comparing a cohort with mild dysplasia and cam femoroacetabular impingement (cohort D) to a cohort with mixed FAI (cohort M). Outcome measures included Nonarthritic Hip Score (NAHS) and satisfaction with minimum 2-year follow-up.

RESULTS

Of 150 patients/159 hips enrolled in the initial prospective outcome study, 10 patients/10 hips had acetabular dysplasia and 8 patients met the inclusion criteria. Cohort D had 8 patients (5 female) of mean age 49.6 years with mean lateral center-edge angle (LCEA) of 19° (range, 16°-24°) demonstrating a mean change in NAHS of +20.00 at 3 months (P = .25), +14.33 at 12 months (P = .03), and -0.75 at 24 months (P = .74). Mean satisfaction was 2.88 out of 5. Cohort M had 69 patients (32 female) of mean age 38.6 years with a mean LCEA of 33° (range, 25°-38°) demonstrating a mean change in NAHS of +12.09 at 3 months (P < .0001), +20.39 at 12 months (P < .0001), and +21.99 at 24 months (P < .0001). Mean satisfaction was 3.58 out of 5. Cohort D demonstrated significantly less improvement in NAHS (P = .002) and a difference of -31.06 points compared to cohort M at minimum 2-year follow-up. Dysplasia was the only statistically significant predictor of poorer outcomes.

CONCLUSION

The common combination of mild dysplasia and cam FAI has poorer outcomes than mixed FAI following arthroscopic surgery without capsular repair.

A comparison of multidisciplinary team residential rehabilitation with conventional outpatient care for the treatment of non-arthritic intra-articular hip pain in UK Military personnel - a protocol for a randomised controlled trial

BACKGROUND

Non-arthritic hip disorders are defined as abnormalities of the articulating surfaces of the acetabulum and femur before the onset of osteoarthritis, including intra-articular structures such as the acetabular labrum and chondral surfaces. Abnormal femoroacetabular morphology is commonly seen in young men who constitute much of the UK military population. Residential multidisciplinary team (MDT) rehabilitation for patients with musculoskeletal injuries has a long tradition in the UK military, however, there are no studies presenting empirical data on the efficacy of a residential MDT approach compared with individualised conventional outpatient treatment. With no available data, the sustainability of this care pathway has been questioned. The purpose of this randomised controlled trial is to compare the effects of a residential multidisciplinary intervention, to usual outpatient care, on the clinical outcomes of young active adults undergoing treatment for non-arthritic intra-articular hip pain.

METHODS/DESIGN

The trial will be conducted at the Defence Medical Rehabilitation Centre, Headley Court, UK. One hundred military male participants with clinical indicators of non-arthritic intra-articular hip pain will be randomly allocated to either: (1) 7-day residential multidisciplinary team intervention, n = 50; (2) 6-week physiotherapist-led outpatient intervention (conventional care), n = 50. Measurements will be taken at baseline, post-treatment (1-week MDT group; 6-weeks physiotherapy group), and 12-weeks. The primary outcome measures are the function in daily living sub-scale of the Copenhagen Hip and Groin Outcome Score (HAGOS), the physical function subscale of the Non-arthritic Hip Score (NAHS), and VAS pain scale. Secondary outcomes include objective measures of physical capacity and general health. An intention-to-treat analysis will be performed using linear and mixed models.

DISCUSSION

This study will be the first to assess the efficacy of intensive MDT rehabilitation, versus conventional outpatient care, for the management of non-arthritic hip pain. The results from this study will add to the evidence-base and inform clinical practice for the management of intra-articular non-arthritic hip pain and femoroacetabular impingement in young active adults.

TRIAL REGISTRATION

ISRCTN Reference: ISRCTN 59255714 dated 11-Nov-2015.

Hip Osteoarthritis: Etiopathogenesis and Implications for Management

Highly prevalent among the elderly, hip osteoarthritis (OA) carries a heavy burden of disease. Guidelines for the management of hip OA are often extrapolated from knee OA research, despite clear differences in the etiopathogenesis and response to treatments of OA at these sites. We propose that hip OA requires specific attention separate from other OA phenotypes. Our understanding of the etiopathogenesis of hip OA has seen significant advance over the last 15 years, since Ganz and colleagues proposed femoroacetabular impingement (FAI) as an important etiological factor. This narrative review summarizes the current understanding of the etiopathogenesis of hip OA and identifies areas requiring further research. Therapeutic approaches for hip OA are considered in light of the condition’s etiopathogenesis. The evidence for currently adopted management strategies is considered, especially those approaches that may have disease-modifying potential. We propose that shifting the focus of hip OA research and public health intervention to primary prevention and early detection may greatly improve the current management paradigm.

Hip Pain in the Pre-Arthritic Patient: A Guide for the Primary Care Physician

Adolescents and young adults (less than 30 years of age) with pre-arthritic hip pain constitute a diagnostic dilemma for the primary care physician. The most common underlying diagnoses range from benign muscle strains/joint sprains to stress reactions, insufficiency fractures, and tears involving the articular cartilage/labrum in the setting of femoroacetabular impingement, a hip shape abnormality that is present in up to 90% of this age group. Undetected or left untreated these seemingly innocuous disorders can result in significant loss of function and, in some cases, irreversible joint damage. Despite sharing common predisposing factors, many of the above diagnoses can be identified with a focused history and physical examination. Conservative management may be safely initiated without advanced imaging, reserving orthopaedic consultation for refractory cases or more serious diagnoses. The presented focused hip clinical examination has 98% sensitivity in localizing intra-articular hip pathology and will be helpful to direct appropriate referrals. This article will serve as a guide for primary care physicians undertaking the difficult task of evaluating and treating a young patient with hip pain.

Correlation Between Cam-Type Femoroacetabular Impingement and Radiographic Osteitis Pubis

A mechanistic link has been suggested between cam-type femoroacetabular impingement and increased stress on the symphysis pubis. This retrospective study was conducted to determine whether there is an increased prevalence of osteitis pubis, as evidenced by imaging, in patients with femoroacetabular impingement compared with age-matched control subjects. Search of a radiologic database of a large academic health institution for all patients with cam-type femoroacetabular impingement diagnosed by magnetic resonance imaging or magnetic resonance arthrogram between January 2000 and October 2013 identified 46 cases. Two radiologists reviewed these cases independently and confirmed the presence of femoroacetabular impingement based on alpha angle and other characteristics of cam morphology. The imaging studies were further evaluated for characteristics of osteitis pubis, with severity graded from minimal to severe on a 4-point Likert scale. A control group composed of age-matched subjects without diagnosed femoroacetabular impingement was also evaluated for osteitis pubis. A statistically significant increase in the prevalence of osteitis pubis was found in patients with femoroacetabular impingement compared with age-matched control subjects, with a prevalence of 43.48% in the femoroacetabular impingement group compared with 12.77% in the control group (P=.0012). On the 4-point Likert scale, the average severity of osteitis pubis in the group with femoroacetabular impingement was 1.5 (minimal to mild) compared with 0.53 (no osteitis pubis to minimal findings) in the control population. This significant increase in osteitis pubis in patients with femoroacetabular impingement supports the clinical link between these 2 processes. [Orthopedics. 2016; 39(3):e417-e422.].

Femoral Head Avascular Necrosis Is Not Caused by Arthroscopic Posterolateral Femoroplasty

This study was conducted to identify the risk of avascular necrosis of the femoral head after arthroscopic femoroplasty extending to the posterolateral femoral neck, the source of the primary blood supply to the femoral head. Cam lesions of femoroacetabular impingement are typically anterior along the junction of the femoral head and neck. However, anatomic variations can involve the posterolateral vascular region of the femoral head and neck. Femoroplasty involving this vascular region can lead to injury to the blood supply to the femoral head, with subsequent avascular necrosis. If the posterolateral portion of the cam lesion is preserved, persistent femoroacetabular impingement may occur. A retrospective review identified 112 patients who underwent arthroscopic femoroplasty for femoroacetabular impingement over a 2-year period. Of these patients, 14 had femoroplasty that extended to the posterolateral femoral head. Of this group, 5 had undergone magnetic resonance imaging (MRI) after femoroplasty and the other 9 were contacted to undergo MRI of the hip to evaluate for avascular necrosis. A radiologist and the senior author evaluated all MRI scans specifically for avascular necrosis of the femoral head. All procedures were performed by the senior author. Mean age of the 14 patients (8 women and 6 men) with femoroplasty that extended into the posterolateral vascular region of the femoral head was 44 years (range, 23-69 years). All 14 patients underwent MRI evaluation of the affected hip a mean of 25 months (range, 7-44 months) after femoroplasty. No MRI scans showed evidence of avascular necrosis of the femoral head. Femoroplasty of the posterolateral vascular region of the femoral head is not associated with avascular necrosis. Patients with femoroacetabular impingement and a cam lesion extending to the posterolateral femoral head can undergo femoroplasty of this region without the development of avascular necrosis. [Orthopedics. 2016; 39(3):177-180.].

Hip arthroscopy in osteoarthritis consequent to FAI

BACKGROUND

Femoral Acetabular Impingement (FAI) means a set of alterations involving the acetabulum, proximal femur, or both of these components that can results in osteoarthritis. Arthroscopy is a choice for the treatment of initial stages of osteoarthritis (OA) in order to reduce evolution of the degenerative processes; advanced degrees of osteoarthritis are absolute contraindications.

MATERIALS AND METHODS

40 patients affected by osteoarthritis in FAI  underwent hip arthroscopy between May 2010 and March 2015. In all 40 cases OA secondary to FAI was diagnosed. All patients were clinically and instrumentally analyzed pre-operatively and then post-operatively after 3, 6, and 12 months. We evaluated the degree of OA using the Tonnis classification; our study included only patients affected by Tonnis grade 0-2 osteoarthritis.

RESULTS

The mean modified Harris Hip Score showed an evolution from 54.7 points to an average value of 89,1 points after 12 months. The Lower Extremities Functional Scale evolved by 43 points to an average value of 65,28 points.

CONCLUSIONS

Based on the data of this study, supported by the concordance with recent literature reviews, in degrees Tonnis 0 and 1 an arthroscopic treatment is recommended. Instead the therapeutic algorithm in Tonnis grade 2 is still being discussed. We detect a significant response to arthroscopic intervention which leads us to suggest that validation of this method needs further confirmatory studies.

Atypical hip pain: coexistence of femoroacetabular impingement (FAI) and osteoid osteoma

The objective of this article was to emphasize the importance of including less common causes of hip pain in a differential diagnosis, particularly when clinical and radiographic variables are atypical. This article presents the case of a 52-year-old patient with a history of progressive hip pain resulting from the coexistence of both a femoroacetabular impingement (FAI) and an intraarticular osteoid osteoma. The intraarticular osteoid osteoma was initially overlooked due to its unremarkable features on radiographic and resonance imaging. Consequently, the patient was surgically treated for FAI with only partial relief. An osteolytic nidus characteristic of osteoid osteoma was discovered only 1.5 years following surgery. The patient was subsequently treated for osteoid osteoma with anti-inflammatories, after which his pain began to resolve. The patient was completely pain free after 7 months. Level of evidence V.

Biochemical MRI predicts hip osteoarthritis in an experimental ovine femoroacetabular impingement model

BACKGROUND

Cam-type femoroacetabular impingement (FAI) resulting from an abnormal nonspherical femoral head shape leads to chondrolabral damage and is considered a cause of early osteoarthritis. A previously developed experimental ovine FAI model induces a cam-type impingement that results in localized chondrolabral damage, replicating the patterns found in the human hip. Biochemical MRI modalities such as T2 and T2* may allow for evaluation of the cartilage biochemistry long before cartilage loss occurs and, for that reason, may be a worthwhile avenue of inquiry.

QUESTIONS/PURPOSES

We asked: (1) Does the histological grading of degenerated cartilage correlate with T2 or T2* values in this ovine FAI model? (2) How accurately can zones of degenerated cartilage be predicted with T2 or T2* MRI in this model?

METHODS

A cam-type FAI was induced in eight Swiss alpine sheep by performing a closing wedge intertrochanteric varus osteotomy. After ambulation of 10 to 14 weeks, the sheep were euthanized and a 3-T MRI of the hip was performed. T2 and T2* values were measured at six locations on the acetabulum and compared with the histological damage pattern using the Mankin score. This is an established histological scoring system to quantify cartilage degeneration. Both T2 and T2* values are determined by cartilage water content and its collagen fiber network. Of those, the T2* mapping is a more modern sequence with technical advantages (eg, shorter acquisition time). Correlation of the Mankin score and the T2 and T2* values, respectively, was evaluated using the Spearman's rank correlation coefficient. We used a hierarchical cluster analysis to calculate the positive and negative predictive values of T2 and T2* to predict advanced cartilage degeneration (Mankin ≥ 3).

RESULTS

We found a negative correlation between the Mankin score and both the T2 (p < 0.001, r = -0.79) and T2* values (p < 0.001, r = -0.90). For the T2 MRI technique, we found a positive predictive value of 100% (95% confidence interval [CI], 79%-100%) and a negative predictive value of 84% (95% CI, 67%-95%). For the T2* technique, we found a positive predictive value of 100% (95% CI, 79%-100%) and a negative predictive value of 94% (95% CI, 79%-99%).

CONCLUSIONS

T2 and T2* MRI modalities can reliably detect early cartilage degeneration in the experimental ovine FAI model.

CLINICAL RELEVANCE

T2 and T2* MRI modalities have the potential to allow for monitoring the natural course of osteoarthrosis noninvasively and to evaluate the results of surgical treatments targeted to joint preservation.

[Hip dysplasia]

Hip dysplasia and femoroacetabular impingement are frequent causes of hip pain and can often be treated with joint preserving surgery to prevent secondary osteoarthritis (OA). Patient education, progressive resistance training and weight loss at a BMI > 27 kg/m(2) has documented effect on pain and function in primary hip OA. If wound infection occurs after total hip arthroplasty the patient should not be treated with peroral antibiotics but instead be referred to an orthopaedic surgeon. There is no documentation that post-operative movement restrictions prevent dislocation of hip after total hip arthroplasty.

A review of outcomes of the surgical management of femoroacetabular impingement

INTRODUCTION

Femoroacetabular impingement (FAI) resulting from abnormal contact between the acetabulum and femur has been studied extensively in recent years owing to its association with acetabular labrum tears and possible contribution to the development of osteoarthritis.

METHODS

A comprehensive PubMed, MEDLINE(®) and Embase™ literature search was conducted. Search terms included 'femoroacetabular impingement', 'pathophysiology', 'diagnosis', 'dGEMRIC', 'arthroscopic', 'open', 'mini-open' and 'outcome measure'.

RESULTS

A range of radiographic features have been described, and computed tomography and magnetic resonance imaging are both commonly used in the diagnosis of the bony abnormalities in FAI. Treatment of FAI is surgical with methods of treatment ranging from open surgical hip dislocation to arthroscopic osteochondroplasty.

CONCLUSIONS

In recent years, a trend towards the use of arthroscopic treatment for FAI has been seen, with promising results from a range of studies. However, only short-term outcome data are available and a range of different outcome measures have been used in studies to date. We present an overview of the outcomes for a range of surgical treatment methods for FAI and discuss the outcome measures used.

Hip pain in the young, active patient: surgical strategies

Hip disorders in young patients likely exist as a spectrum of prearthritic and arthritic conditions. With the increasing recognition of these disorders, surgical options are being popularized and more patients are being treated at a younger age. Hip surgeons must develop a careful set of evidenced-based indications and follow surgical outcomes in a rigorous, scientific manner. Hip arthroscopy can be used to successfully treat some hip disorders, including labral tears, with or without femoroacetabular impingement, resulting in mechanical symptoms. Long-term outcomes after arthroscopy are determined by the condition of the cartilage at the time of surgery. Patients with preoperative radiographic evidence of moderate to severe arthritis have poor outcomes when treated with arthroscopy. Open joint preservation procedures (including periacetabular osteotomy and surgical hip dislocation with osteochondroplasty) can be done in the absence of substantial arthritis to treat hip dysplasia, femoroacetabular impingement, and related conditions. The results of these procedures are good in appropriately selected patients at short-term to midterm follow-ups. In the presence of severe arthritis, joint replacement is the treatment of choice. Total hip arthroplasty using uncemented acetabular and femoral fixation provides reliable osseointegration; however, long-term results in young patients have historically been compromised by bearing surface wear, osteolysis, and component loosening. Contemporary, highly cross-linked polyethylene and ceramic-on-ceramic bearings have durable results, low complication rates, and offer the potential of long-term survivorship in this high-demand population. In general, metal-on-metal implants have higher complication rates versus other bearing surface options and should be avoided. The best results of hip resurfacing are seen in men younger than 55 years with large femoral head sizes. Although implant survivorship is comparable to that of total hip arthroplasty, the sequelae of metal wear debris continue to cause concern.

Valgus hip with high antetorsion causes pain through posterior extraarticular FAI

BACKGROUND

Valgus hips with increased antetorsion present with lack of external rotation and posterior hip pain that is aggravated with hip extension and external rotation. This may be the result of posterior femoroacetabular impingement (FAI).

QUESTIONS/PURPOSES

We asked whether (1) the range of motion (ROM); (2) the location of anterior and posterior bony collision zones; and (3) the prevalence of extraarticular impingement differ between valgus hips with increased antetorsion compared with normal hips and hips with idiopathic FAI.

METHODS

Surface models based on CT scan reconstructions of 13 valgus hips with increased antetorsion, 22 hips with FAI, and 27 normal hips were included. Validated three-dimensional collision detection software was used to quantify the simulated hip ROM and the location of impingement on the acetabular and the femoral sides.

RESULTS

Hips with coxa valga and antetorsion showed decreased extension, external rotation, and adduction, whereas internal rotation in 90° of flexion was increased. Impingement zones were more anteroinferior on the femur and posteroinferior on the acetabular (pelvic) side; and the zones were more frequently extraarticular, posterior, or to a lesser degree anterior against the inferior iliac spine. We found a higher prevalence of extraarticular impingement for valgus hips with increased antetorsion.

CONCLUSIONS

Valgus hips with increased antetorsion predispose to posterior extraarticular FAI and to a lesser degree anteroinferior spine impingement.

Shared morphology of slipped capital femoral epiphysis and femoroacetabular impingement in early-onset arthritis

A subclinical form of slipped capital femoral epiphysis (SCFE) can lead to subtle morphologic abnormalities, such as cam-type femoroacetabular impingement (FAI). Femoroacetabular impingement is a mechanical hip abnormality that typically affects young populations and leads to hip pain and premature osteoarthritis. Imaging is critical to diagnosis, whether by radiograph, magnetic resonance imaging, or computed tomography. The authors investigated the use of imaging to detect characteristics of subclinical SCFE and cam-type FAI in patients undergoing hip resurfacing. They retrospectively assessed computed tomography scans of 81 hips from 75 patients. Measurements were taken of the proximal femur and included the alpha angle, head-neck tilt, and anterior offset taken in both the conventional oblique axial plane and the radial plane. The cohort consisted of 68 men and 13 women with an average age of 52 years. Ninety percent of hips on the oblique axial view and 95% of hips on the radial view were found to have pathologically increased alpha angles. Negative correlations were found between the alpha angle and head-neck tilt and positive correlations between head-neck tilt and anterior offset ratio. Sixty percent and 68% of hips in the oblique axial and radial planes, respectively, were abnormal for the alpha angle, head-neck tilt, and anterior offset ratio, strongly suggesting SCFE morphology. This study's results show similarity in morphology between cam-type FAI and SCFE, known precursors to osteoarthritis, in an early arthritic patient population.

Effects of posterior pelvic tilt on anterior instability in total hip arthroplasty: a parametric experimental modeling evaluation

BACKGROUND

Anterior dislocation is one of the concerns of patients with posterior pelvic tilt undergoing total hip arthroplasty. This study aimed to evaluate the magnitude of posterior pelvic tilt constituting a risk for anterior dislocation by measuring the range of motion until impingement and dislocation under various pelvic tilt.

METHODS

Using a jig mounted prosthetic hip model, the ranges of external rotation at extension and internal rotation at flexion until reaching dislocation were tested. The site of impingement prior to dislocation was also recorded. Posterior pelvic tilt and the cup version were changed with 10° increments from 0° to 40° and from 10° retroversion to 30° anteversion, respectively. Effects of increasing femoral offset were also tested. We defined a required range of motion as having 30° external rotation at extension and 40° internal rotation at 90° flexion.

FINDINGS

External rotation decreased in a posterior pelvic tilt-dependent manner. In the case with more than 20° posterior pelvic tilt, available external rotation extended beyond required range with the cup anteversion of 20°. Decreasing cup anteversion improved external rotation, however, internal rotation decreased simultaneously. In the case with posterior pelvic tilt more than 20°, only cup anteversion with 0° or 10° satisfied the required range of motion. A +4 mm horizontal offset improved external rotation by 10° with delaying bony impingement.

INTERPRETATION

More than 20° of posterior pelvic tilt may cause anterior instability and diminish the optimal range of cup version. Increasing the femoral offset improved external rotation without reducing internal rotation.

Advances in hip preservation after slipped capital femoral epiphysis

The metaphyseal deformity, in even a mild slipped capital femoral epiphysis (SCFE), results in acetabular labral and cartilage injury. SCFE is the most extreme form of femoroacetabular impingement, and the mechanism of cartilage and labral injuries is similar. Recent surgical advances for treating femoroacetabular impingement have made it possible to consider applying these techniques to the surgical treatment of SCFE deformities to lessen the risk of secondary osteoarthritis. The goals of treatment are to arrest slip progression and restore normal proximal femoral anatomy, thereby decreasing damage to the hip joint secondary to impingement. In situ pinning is the most effective treatment to halt short-term slip progression; outcomes are favorable in many hips. In medical centers with substantial experience with hip preservation techniques, open or arthroscopic osteochondroplasty can be used to treat mild SCFE, and a modified Dunn epiphyseal reorientation can be used for more severe deformities to decrease the potential for secondary osteoarthritis.

The aspherical human hip: implication for early osteoarthritis

One marker for early-onset hip arthritis is femoral acetabular impingement. The current standard way of quantifying impingement is manual calculation of anatomical measures on plain radiographs, including the α-angle. Such measurements are user-dependent and prone to error. We provided a robust computational alternative and proposed using numerical fitting of geometrical shapes. We applied least-squares fitting of an ellipse to the femoral head contour and used the difference between the ellipse axes as a quantification method. The results showed a good correlation between the new measure and previous definitions of the α-angle.