Modified head-neck offset for diagnosing anterior femoro-acetabular impingement

Predictive radiological parameters of failure following surgical management of femoroacetabular impingement associated with borderline acetabular dysplasia

INTRODUCTION

The role of arthroscopic treatment of femoroacetabular impingement (FAI) in mild or borderline hip dysplasia (lateral center edge angle=18-25) is controversial. It is recommended to combine capsular plication with femoral neck osteoplasty and suture repair of the labrum. Few studies have investigated which radiological parameters are associated with failure of this procedure.

HYPOTHESIS

A larger number of radiological signs of mild or borderline hip dysplasia than radiological signs of FAI negatively influence the outcomes of arthroscopic treatment.

METHODS

This was a retrospective study done with data collected prospectively after a minimum of 2 years' follow-up in patients who underwent arthroscopic treatment of FAI due to cam impingement combined with mild to moderate hip dysplasia. Patients with hip osteoarthritis graded as ≥ Tönnis 2 were excluded. Functional outcome scores (mHHS and NAHS) were determined along with the need for reoperation. Three groups were defined based on the outcomes: success (mHHS ≥ Patient Acceptable Symptomatic State [PASS]); moderate improvement (improvement in mHHS + mHHS<PASS) and failure (worsening of the mHHS). Demographic data, radiographic parameters (LCEA, Tönnis angle, alpha angle, offset, FEAR index, Shenton's line, Cliff sign, anterior wall index [AWI], posterior wall index [PWI]) and intraoperative findings were compared between these three groups. The area under the curve (AUC) for the most relevant data identified during the univariate analysis were then modeled to define which factors were the best at predicting failed arthroscopic treatment a posteriori.

RESULTS

The study analyzed 39 patients. The mean mHHS was 76±15 [40-92]. The "success" group consisted of 21 patients (56%, 21/39), the "moderate improvement" group of 12 patients (31%, 12/39) and the failure group of 6 patients (13%, 6/39) (2 subsequently underwent total hip replacement, 4 underwent shelf acetabuloplasty). The FEAR index was significantly higher and the AWI and VCE were significantly lower in the "failure" group. The FEAR index was the best predictive factor; an index ≥ 4° detected 100% of failures with 96% specificity. The patients in the "moderate improvement" group were significantly older (37 years±8 [18-45]<p= 0.04) with a significantly higher offset (2mm±3 [-5-5]<p=0.004); an offset ≥ 2mm could detect 73% of them with a specificity of 72%.

CONCLUSION

A FEAR index ≥ 4° and offset ≥ 2mm is best able to detect patients at risk of failure and unsatisfactory results, respectively, in the mild clinical cam-type impingement in a population of FAI patients.

LEVEL OF EVIDENCE

IV, retrospective series.

Primary cam morphology; bump, burden or bog-standard? A concept analysis

BACKGROUND

Cam morphology, a distinct bony morphology of the hip, is prevalent in many athletes, and a risk factor for hip-related pain and osteoarthritis. Secondary cam morphology, due to existing or previous hip disease (eg, Legg-Calve-Perthes disease), is well-described. Cam morphology not clearly associated with a disease is a challenging concept for clinicians, scientists and patients. We propose this morphology, which likely develops during skeletal maturation as a physiological response to load, should be referred to as primary cam morphology. The aim of this study was to introduce and clarify the concept of primary cam morphology.

DESIGN

We conducted a concept analysis of primary cam morphology using articles that reported risk factors associated with primary cam morphology; we excluded articles on secondary cam morphology. The concept analysis method is a rigorous eight-step process designed to clarify complex 'concepts'; the end product is a precise definition that supports the theoretical basis of the chosen concept.

RESULTS

We propose five defining attributes of primary cam morphology-tissue type, size, site, shape and ownership-in a new conceptual and operational definition. Primary cam morphology is a cartilage or bony prominence (bump) of varying size at the femoral head-neck junction, which changes the shape of the femoral head from spherical to aspherical. It often occurs in asymptomatic male athletes in both hips. The cartilage or bone alpha angle (calculated from radiographs, CT or MRI) is the most common method to measure cam morphology. We found inconsistent reporting of primary cam morphology taxonomy, terminology, and how the morphology is operationalised.

CONCLUSION

We introduce and clarify primary cam morphology, and propose a new conceptual and operational definition. Several elements of the concept of primary cam morphology remain unclear and contested. Experts need to agree on the new taxonomy, terminology and definition that better reflect the primary cam morphology landscape-a bog-standard bump in most athletic hips, and a possible hip disease burden in a selected few.

Is hip arthroscopy useful in the treatment of borderline dysplasia?: a case-control study

INTRODUCTION

Since arthroscopy remains a controversial treatment of hip dysplasia, our objective was to analyse its clinical and radiological results in a cohort of patients with dysplasia and compare them to controls with femoroacetabular impingement (FAI).

MATERIAL AND METHODS

We retrospectively analysed a series of patients who underwent hip arthroscopy for the treatment of labral pathology; 29 of them with borderline hip dysplasia and 197 with FAI, comparing reoperations and joint survival. The diagnosis of borderline dysplasia was made with a lateral centre-edge angle greater than 18° but less than 25°. The average follow-up was 43 months. We performed a multivariate regression analysis to evaluate the association of reoperations with different demographic, radiological and intraoperative variables.

RESULTS

Seven complications were registered in the FAI group (1 medically treated superficial wound infection, 3 pudendal nerve paraesthesias, 1 deep vein thrombosis and 2 heterotopic ossifications) and none in the dysplasia group. While 5 patients from the FAI group required a new surgery, none of the dysplasia group was re-operated (p=.38). After adjusting for confounders, reoperation showed a very strong association with the finding of osteochondral lesions during index surgery, with a coefficient of .12 (p<.001, 95%CI=.06-.17).

CONCLUSION

Hip arthroscopy was useful in the treatment of borderline dysplasia, without non-inferior survival compared to the FAI group. We suggest indicating it carefully in dysplasia cases, whenever the symptoms of femoroacetabular friction prevail over those of instability.