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Abstract
Objective To compare the results of hip arthroscopy in patients under the age of 25 with those over 25 years.
Design From March 2006 until May 2010, data were collected on all patients who underwent hip arthroscopy for symptomatic intra-articular hip pathology. The patients were divided into two groups based on age (less than 25 years and over 25 years). Patients completed the modified Harris hip score (MHHS), non-arthritic hip score (NAHS) and hip dysfunction and osteoarthritis outcome score (HOOS) questionnaires at baseline then at 6 weeks, 6 months, 12 months and at latest follow-up.
Participants 88 patients who underwent 94 hip arthroscopies by the senior author. Mean age was 24.3 (range 11–57 years).
Results The mean NAHS and HOOS subscales for pain and activities of daily living were worse at baseline in over 25 groups. Follow-up ranged from 9 to 68 months. 45 hips had greater than 3 year follow-up. The MHHS improved in both groups with a mean difference in the under-25 group of 16.22, and 20.88 in the over 25s. Improvements in the NAHS and HOOS subscales were also of a similar magnitude. There was no statistically significant difference between outcome scores of the two groups at the latest follow-up visit.
Conclusions We found a comparable improvement in outcome between those patients under 25 years and those over 25 years. We propose that hip arthroscopy is of potential benefit to patients with symptoms of femoroacetabular impingement regardless of age.
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Introduction
Traditionally, intra-articular hip pathology in young adults has been a challenging problem to diagnose and treat. Over the past decade, the indications, recent advances, outcomes and complications for hip arthroscopy have been widely studied and reported.1 ,2 There is, however, a limited amount of published research and long-term reports of clinical outcome. More encouraging long-term follow-up studies are now emerging.3
Hip arthroscopy was first performed on cadavers by Burman in 1931.4 This procedure has gained increased popularity in the last two decades. Increased understanding of hip anatomy and pathology in younger people, along with more sensitive diagnostic techniques, particularly MRI and arthrography, has facilitated the increased accuracy in diagnosis of intra-articular hip pathology.5 Furthermore, improved knowledge of how best to position the patient for surgery and distract the joint has expedited the advancement of arthroscopic techniques and procedures within the hip joint.6–11 Careful selection of patients and appropriate indications remain of paramount importance in achieving successful results.
Hip pain is disabling and can affect daily function and quality of life. Tears of the acetabular labrum may result in hip and groin pain and restriction of range of motion in young, active patients.12 Causes of labral tears include femoroacetabular impingement (FAI),13 capsular laxity, degeneration, dysplasia and trauma. Recent understanding of the pathomechanics behind labral tears has enabled surgeons to correct the intra-articular bony abnormalities (eg, FAI) that cause these tears as opposed to addressing the tears alone, which has led to treatment failures previously.14–18
FAI was first described by Smith-Petersen in 1936.19 FAI has been described as a pathomechanical process resulting in abnormal contact stresses within the hip joint resulting in damage to the articular cartilage, labrum and bony architecture.14 ,20 ,21 FAI is identified radiologically by a structural abnormality of the proximal femur or acetabulum that results in impingement within the normal range of motion of the hip. This results in damage to the acetabular cartilage and/or labrum.22 This bony impingement may be due to an aspherical femoral head (cam type), an unusually deep acetabulum (pincer type) or a combination of the two (mixed FAI). It is reported that the prevalence of cam-type FAI is approximately 14% in the general asymptomatic population.23 This particular deformity may be associated with high-intensity sports activity in adolescence and is up to twice as common in men than women.24 ,25 Clinical findings in FAI include restriction of movement, ‘clicking’ in the hip joint and pain. These symptoms can be exacerbated by activities involving hip flexion or prolonged sitting. FAI is now emerging as a potential precursor of osteoarthritis in young adults.26–29
Young patients with hip pain are often referred to sports surgeons despite having a moderate or low sporting activity level. The aim of our study was to analyse the results of hip arthroscopy in non-elite (in terms of level of sporting activity) patients, specifically comparing the under 25s with the over 25s. We report our indications, findings and results of a consecutive series of patients who underwent hip arthroscopy performed by one surgeon (this paper's fifth author SSM).
Background
Our adult hospital serves a catchment area of approximately two million people as a tertiary referral centre for the young adult hip service. The paediatric hospital covers a catchment area of 1.8 million.
We conducted this study as a service review in accordance with the National Institute for Health and Clinical Excellence guidance for arthroscopic femoroacetabular surgery for hip impingement syndrome.30 Approval for the study was obtained from the local clinical effectiveness committees. Patient consent was obtained in order to use the data collected, including that from outcomes scoring, for the purpose of service evaluation.
Methods
Assessment
Between March 2006 through May 2010, 88 consecutive patients underwent 94 hip arthroscopy procedures performed by the senior author (SSM). All patients who underwent hip arthroscopy during this period regardless of presenting symptoms, underlying pathology or outcome, were included in this study with no exclusions. Case records, operative notes, imaging studies and subjective outcomes were reviewed.
A detailed clinical assessment which included history and clinical examination findings, including specific clinical tests for FAI (eg, passive internal rotation in 90° of flexion and adduction),5 ,31 was recorded for each patient. Initial imaging included plain radiographs, specifically an antero-posterior view of the pelvis and a cross-table lateral of the affected hip, which was performed for all patients. All patients also underwent magnetic resonance arthrography due to its high sensitivity in detecting hip joint pathology.5 ,32 ,33 Further imaging modalities utilised included x-ray CT scanning and diagnostic hip injection as determined on an individual basis. A surgeon-based proforma was designed to record the demographics, indications, radiological and surgical findings.
Self-reported patient outcome data collected included the modified Harris hip score (MHHS),34 non-arthritic hip score (NAHS)35 and hip dysfunction and osteoarthritis outcome score (HOOS).36 These outcome scores were completed preoperatively and at 6 weeks, 3 months, 6 months and then every 12 months and at latest follow-up.
Indications for surgery included mechanical symptoms or pain in the hip, which was unresponsive to non-operative measures (analgesia, activity modification and physiotherapy), and radiological evidence of intra-articular pathology that would be amenable to arthroscopic treatment (eg, FAI, labral tears and chondral lesions).
Surgical technique
Our surgical technique is the standard hip arthroscopy technique previously described.11 Under general anaesthesia, patients were positioned supine on a fracture table. Traction was applied using a hip distractor attached to the leg (foot piece) and counter traction was obtained with a well-padded perineal post with the hip in approximately 15° of adduction, 20° of flexion and in neutral to slight external rotation. We performed the first 30 cases with three portals and then moved on to a two portal technique using the anterolateral and the lateral portals, thus avoiding the anterior and the posterolateral portals and the potential risks associated with those.
Outcomes
The MHHS asks eight questions on pain (44 points) and functional activities (47 points). A multiplier of 1.1 is applied to give a total possible score of 100.3 ,34 This score is a recognised and accepted method for quantifying subjective outcomes following hip arthroscopy and has been modified from the original score by removing range of movement (ROM) and deformity assessment from the score to facilitate self-reporting.34 ,37
There are 20 questions on the NAHS questionnaire with a maximum of 80 points. A multiplier of 1.25 is then applied to the total, to produce a score out of 100. This score has been validated in a population of younger patients with hip pain, who have high treatment expectations,35 similar to the subjects in our study.
The HOOS score has five subscales (symptoms, pain, function in activities of daily living, function in sport and quality of life).36 Each subscale was scored and reported separately. It was designed to assess hip disability in patients with and without osteoarthritis.
When this study was started, no specific outcome score for hip arthroscopy had been designed, therefore we chose to utilise the three scores selected. The MHHS and NAHS are recommended by the International Society for Hip Arthroscopy38 as outcomes instruments to be used for research purposes.37 The HOOS allows detailed assessment of change in condition for different subsets of symptoms.
Statistical analysis
Statistical analysis was performed using SPSS V.19.0 (IBM, Armonk, New York, USA). A Shapiro-Wilk test and a Q–Q plot were performed and normality of the data was confirmed. As such, parametric tests were used to compare the two groups (eg, Student's t-test). Statistical significance was defined as a p value of less than 0.05.
Results
There were 51 (58%) females and 37 (42%) male patients. The age range was 11–57 years (mean age 24.3). The patients were split into two groups based on age at surgery (less than or over 25 years of age) for the purposes of analysis (table 1). Follow-up ranged from 9 to 68 months. 45 hips had more than 3-year follow-up (mean 45.3 months).
Age distribution of participants
Twenty-eight patients were actively participating in sports at presentation to our service, including football, cycling, running, rugby, martial arts and horse riding. Twenty patients had an associated limp and 16 suffered with clicking of the hip joint on walking. All patients complained of pain on walking. Thirty-nine patients had pain on sitting for prolonged periods and five patients had regular sleep disturbance. Nine patients described associated knee pain. Fourteen patients complained of pain in the hip on impact activities (eg, jumping) with 22 patients reporting that their pain prevented them from playing sports.
Previous and associated hip pathology included slipped capital femoral epiphysis, Legg-Calve-Perthes disease, developmental hip dysplasia, proximal femoral fractures, avascular necrosis of the femoral head and spina bifida (table 2). Two patients had undergone contralateral surgical dislocation (Ganz technique) and labral repair previously. One had had open excision of exostosis and heterotopic ossification of rectus femoris. Two other patients had prior knee arthroscopy and lateral release. Twelve patients had previously undergone diagnostic hip injection with a local anaesthetic agent (bupivacaine).
Preoperative diagnoses
Arthroscopic procedures performed included debridement of labral tears and chondral lesions, microfracture, burring to correct head/neck offset, rim trim and labral repair (table 3). Articular cartilage lesions were quantified intraoperatively using the Outerbridge scale.39 Advanced osteoarthritis (Outerbridge grade IV—exposed subchondral bone) was found in 12 hips.
Procedures performed at arthroscopy
There was no incidence of venous thromboembolism, pudendal nerve injury, perineal injury, intraoperative adverse event, avascular necrosis or fracture in our series. Among the complications, one had a superficial portal site infection and required oral antibiotics. One patient had a transient neurapraxia that resolved spontaneously. One patient developed trochanteric bursitis which subsequently settled with a steroid injection.
Five patients in this series have been lost to follow-up. These patients were treated at the paediatric hospital and have since moved away from living with their parents.
Outcomes
There were no statistically significant differences in preoperative hip scores except for the mean NAHS and HOOS subscales for pain and activities of daily living which were worse in the over-25 patient group (table 4).
Mean (±SD) baseline (preoperative) patient-reported outcome measures
The majority of participants in this study demonstrated an improvement in self-reported hip outcomes measures at 6 weeks postoperatively, and this improvement was maintained during the follow-up period (tables 5 and 6).
Mean (±SD) modified Harris hip score (MHHS) and non-arthritic hip score (NAHS) over 12-month follow-up period
Difference in mean outcome scores at latest follow-up compared with preoperative scores
Both groups demonstrated a mean improvement in self-reported hip health of between 16 and 24 points per score/subscale (table 6). There was no significant difference between outcomes scores in the two groups at latest follow-up (table 7).
Mean (±SD) patient-reported outcome measure scores at latest follow-up
We arbitrarily defined our results as excellent (improvement >20 points each score/subscale, back to all ADLs and sports), good (improvement >20 points, ADLs fine, no sports), fair (improvement of less than 20 points) and poor (decline in score, worsening symptoms and function).
Excellent results were achieved for 61 hips (64.9%). A further 12 hips (12.8%) achieved a good result and fair results were noted in 11 hips (11.7%). A poor result was seen in 10 hips (10.6%).
Of the subjects with fair or poor results (21 hips), 11 had Outerbridge grade IV osteoarthritis on hip arthroscopy with significant chondral lesions (>25%) of the acetabulum. Two patients within this group went on to have surgical dislocation for treatment for FAI. Of these two, one needed labral repair and the other proceeded to have a total hip replacement (THR) 1-year postarthroscopy. In the over-25 group, one patient went on to have hip resurfacing 2-years after arthroscopy and three underwent THR (two at 2-years and one at 3-years). However, one patient with grade IV arthritic change on arthroscopy still has excellent symptom relief at 3 years.
Discussion
Hip arthroscopy can reduce pain and improve function in patients with intra-articular hip pathology including femoroacetabular impingement and labral tears.40–42 There have been numerous studies looking at outcomes in hip arthroscopy in young adults and athletes.43 ,44 A recent article has also examined outcomes in cam impingement treated with arthroscopic osteoplasty in patients over 60 years of age.45 Our study is the only study to date that compares outcomes in adolescents and young adults up to the age of 25 with those in adults over 25 years.
In the under-25 group, six subjects had Outerbridge grade III or IV arthritis confirmed arthroscopically. Three of these patients demonstrated no improvement or deterioration in all three scores at the latest follow-up. Of these, two had a preoperative diagnosis of avascular necrosis and the other had juvenile idiopathic arthritis. In this small subset the pre-existing condition was thought to be a stronger predictor of outcome than arthroscopically diagnosed chondropathy.
Our results are in accordance with previous studies that suggest that preoperative arthritis and chondral damage appears to be a negative prognostic factor on the clinical outcome.18 ,46 A prospective study by Byrd and Jones of a cohort of 50 patients (52 hips) since 1993 that were followed up to 10 years showed the median improvement was 25 points using the MHHS and demonstrated that the presence of osteoarthritis was an indicator of poor prognosis in the long term.3
Magnetic resonance arthrography with gadolinium enhancement is our investigation of choice owing to the high sensitivity (>90%) of this test in diagnosing intra-articular hip pathology.32 ,33 We have noticed progressively accurate reporting for intra-articular hip pathology in the young, including labral tears. Identification of chondral lesions preoperatively remains a challenge, including in patients with Tönnis grade I and II osteoarthritis.47 We found that patients with significant chondral lesions, in particular those who had involvement of more than 25% of the articular surface, did not have as good an outcome as the rest of the cohort. Our incidence of THR was similar to that previously observed. Haviv et al48 cite a 16% incidence of THR over 7 years in 564 patients with osteoarthritis and found that factors influencing time to THR included age and degree of osteoarthritis.
Although we did not specifically focus on results for patients who participated in sporting activity, other studies have concluded that arthroscopy has a good clinical outcome. In a study of 45 professional athletes by Philippon et al,49 42 (93%) returned to competitive sports post arthroscopy and decompression for FAI. The three patients who could not return to sports were found to have diffuse arthritic changes in the hip joint. This is in concordance with our findings that patients with arthroscopically proven chondral lesions tend to do less well than patients who do not.
The lateral positioning as described by Glick et al9 has been adopted by many surgeons worldwide. However, we find a supine position, as popularised by Byrd et al,3 ,7 more familiar and have not experienced any intraoperative problems with this technique. This is supported by our relatively low complication rate. One patient in our study developed transient paraesthesia. Kamath et al50 reviewed clinical outcomes in 52 patients who underwent hip arthroscopy. In this cohort, four patients developed transient nerve palsies postoperatively. The frequency of complications following hip arthroscopy is reported to be less than 1.5% with failure to identify and treat the abnormality or incompletely addressing the bony deformities being the main cause of secondary procedures.51
We have identified some limitations of our study. The number of patients in this study is small and some patients have a relatively short follow-up (range: 9–68 months). There was no control group to compare arthroscopy with; however, the majority of patients referred to our service had previously had an unsuccessful trial of non-operative management for their hip symptoms.
The outcome measures used in this study to monitor results of hip arthroscopy have not been specifically validated in a hip arthroscopy population. This is a source of potential bias in our study. The MHHS is an imperfect instrument as the original score was designed to assess hip arthroplasty.37 It is, however, an accepted outcome tool which has been used for analysing the results of hip arthroscopy.3 ,34 The NAHS is not specific for hip arthroscopy but has been validated for the assessment of outcomes in younger patients with higher demands and expectations of treatment.35 The HOOS questionnaire was designed to assess outcomes in patients with hip disability both with and without osteoarthritis.36 It should be noted that the outcome scores we employed did not include any psychometric properties and as such this may be a source of potential bias when comparing different population groups. A systematic review conducted by Tijssen et al52 in 2011 concluded that there was no single best outcome measure for evaluating patients undergoing arthroscopic hip surgery, which supports our decision to use multiple outcome measures.
Conclusions
With careful patient selection and increasing surgical expertise, hip arthroscopy can be established as a successful day-case procedure. Further studies with long-term follow-up are required to expand the evidence base and examine the potential impact of hip arthroscopy on future need for arthroplasty procedures.
In our experience, patients with significant chondral lesions (>25% acetabular involvement) and established hip osteoarthrosis tend to have a more modest improvement following arthoscopic surgery. Both the patient and surgeon should be aware of this and also of the risk of symptom deterioration despite surgical intervention.
The majority of publications to date have focused on the young athlete. This study compares subjective outcomes in two age groups and does not concentrate on those patients who have a high preoperative level of sporting activity. Our data show an equal improvement in outcome between those patients under 25 years and those over 25. As such we propose that arthroscopic femoroacetabular surgery is of potential benefit to all patients with symptomatic mechanical hip impingement regardless of level of sporting activity undertaken and should not only be reserved for young elite sportsmen and women.
References
Footnotes
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Contributors All authors in this study were involved in the data collection, analysis and writing of this paper.
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Competing interests None.
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Ethics approval Clinical Governance/Effectiveness departments of both institutions.
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Provenance and peer review Not commissioned; externally peer reviewed.
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▸ References to this paper are available online at http://bjsm.bmjgroup.com