Paper #66 - ISHA Annual Scientific Meeting 2016

Traffic-Light Grading System of Hip Dysplasia to Predict Success Following Hip Arthroscopy

George Grammatopoulos, DPhil, FRCS (Tr&Orth), Reading UNITED KINGDOM
Owain Lloyd Ioan Davies, MA, MBBChir, MRCS, Bangor UNITED KINGDOM
Thomas C.B. Pollard, MD, FRCS (Tr & Orth), Reading UNITED KINGDOM
Antonio (Tony) Andrade, MB BS, FRCS (Tr & Orth), Reading, Berkshire UNITED KINGDOM

Royal Berkshire Hospital NHS Foundation Trust, Reading, Berkshire, UNITED KINGDOM

FDA Status Not Applicable

Summary: We propose a simple grading system for identifying patients with hip dysplasia that may be suitable for treatment with hip arthroscopy.

Abstract:
Introduction

Hip dysplasia has been associated with increased risk of failure following hip arthroscopy. However, some case series of arthroscopic treatment in symptomatic mild/moderate dysplasia have demonstrated that symptomatic improvement can be achieved. Identifying parameters that increase the chance of successful arthroscopy in hip dysplasia would aid surgical decision-making and therefore potentially improve outcomes. The aim of this retrospective cohort study was to identify anatomical and intra-operative features that could predict failure of hip arthroscopy in dysplastic hips.

Methods

This is a retrospective, single-surgeon, cohort series from a UK centre. We reviewed our database of 377 hip arthroscopies performed between 2008 and 2013 (ensuring a minimum 2-year follow-up) at our hospital, and identified 75 patients/hips with features of dysplasia [acetabular index (AI) > 10° and centre-edge angle (CEA) <25°].

We compared clinical, anatomical and radiological features and operative findings between failed (n=27) and preserved (n=48) hips at a mean follow-up of 5 years (range: 3 – 10). Radiographic evaluations of the operated hip (acetabular index, centre-edge angle, extrusion index) were performed using a validated (HipMorf) software programme. Degree of hip dysplasia was defined as mild (AI< 17.5° & CEA: 15 – 25°), moderate (AI: 17.5 – 25° & CEA: 7.5 – 14.9°) or severe (AI> 25°& CEA< 7.5°). Operative findings (presence and extent of articular wear using UCL grading system, labral pathology) and type of procedure performed (labral repair or debridement, osteochondroplasty) were reviewed.

Results

The mean age of the study cohort was 42 (SD:10) years old and most patients were female (n=56). The mean AI was 16° (10.1 – 31.4) and the mean CEA was 13.1° (1.4 – 23.7). There were 29 (39%) mildly, 34 (45%) moderately and 12 (16%) severely dysplastic cases.

There were no gender differences between the groups (p=0.3), however the failed cases were of an older population (p=0.007). Failed cases had more severe features of dysplasia compared to controls; with higher acetabular-index (18° Vs 15°), extrusion-index (0.7 Vs 0.5) and lower centre-edge-angle (10° Vs 15°) (p<0.001).

There was a significant difference in the success of hip preservation between the three dysplasia groups (p<0.0001); arthroscopic treatment failed in only 5/29 (17%) of the mildly dysplastic cases, compared to 12/34 (35%) of the moderate cases and 10/12 (83%) of the severely dysplastic ones. All 5 cases with mild dysplasia that failed had significant articular cartilage damage identified at operation. Similarly, 8 of the 12 cases in the moderate dysplasia group had evidence of articular cartilage damage at the time of operation whilst the remaining 4 had irreparable labral tears.

Discussion

We have been able to develop a traffic light grading system for use when considering arthroscopic treatment in dysplastic hips. Hip arthroscopy is associated with excellent chance of hip preservation in mild (green light) dysplasia (AI< 17.5° & CEA: 15 – 25°) and no articular wear. Hip arthroscopy should not be performed in cases with severe (red light) dysplasia (AI> 25° & CEA< 7.5°). Hip arthroscopy can be offered in moderate dysplasia.