Hip and groin pain are common in the community1 and in sporting populations.2 Contributing conditions include femoroacetabular impingement syndrome (FAI), which affects younger adults and is thought to contribute to early degeneration of the labrum and adjacent cartilage,3 and osteoarthritis (OA) in older populations.4 Other forms of intra-articular hip pathology such as acute labral and ligamentum teres tears may occur through trauma or excessive load and be unrelated to bony morphology or degenerative change.5

Arthroscopy is utilized to treat patients in the early stages of hip pathology by osteoplasty of femoral and acetabular deformities (cam and pincer, respectively), and repair of injuries of the acetabular labrum and adjacent cartilage.6 Pathologies that exist in the advanced stages of OA, such as cartilage defects on the femoral head or in the acetabular region, are considered to be poor prognostic indicators7–10 and a limiting factor for clinical improvement.11,12 When patients with advanced chondropathy or pre-existing OA undergo hip arthroscopy, they report lower patient satisfaction and lower outcomes for function and pain12,13 and tended to be unimproved or even deteriorated at follow-up11,14 when compared to individuals with mild hip chondropathy. The population considered most appropriate for hip arthroscopy are younger, physically active people with unaffected gait and inguinal pain related to movement (flexion and internal rotation) who possess imaging signs of FAI or dysplasia without joint space narrowing, labral tears, or damage in chondrolabral junction.6 Arthroscopic labral debridement in patients without chondropathy resulted in significant improvement post surgery in the clinical scoring systems when compared to patients with articular cartilage lesions,11 with severe chondropathy associated with worse pain and function at eighteen months post surgery.14

Before and following arthroscopy, hip pain and function are frequently measured using patient-reported outcomes (PROs) questionnaires.15,16 Several specific PROs are used to reliably evaluate hip arthroscopic surgery outcomes,17,18 present a patient-focused perspective19 and capture outcomes that are important to patients.20 The intra-class correlation coefficient values for most subscales of the Hip Disability and Osteoarthritis Outcome Score (HOOS) and the International Hip Outcome Tool (iHOT-33) equal or exceed 0.90 indicating that these questionnaires meet acceptable levels of reliability and precision for application at the individual level and group level.21 Along with functional PROs using a Likert scale, such as the Pain on Activity (POA), they measure hip pain and function.22,23 While many studies have outlined the relationship between various pathologies and PRO response post surgery,24–26 the post-operative responses may be mitigated by surgery. The relationships between intra-articular hip pathology and PRO responses prior to surgery have yet to be fully identified. Although PROs are not designed to differentiate between types or severity of pathology, determining the relationship between frequently-used PROs to the intra-articular conditions provoking symptoms may help refine clinical decision making and shape opinion regarding the likely severity of findings during surgery.

The purpose of our study was to determine:

• (1)

  The prevalence of femoral head, acetabular, labral and ligamentum teres pathology in a population assessed by clinical examination and radiological assessment as appropriate for arthroscopic hip surgery.

• (2)

  The association between pre-operative PROs (HOOS, iHOT-33 and POA) and intra-articular findings at hip arthroscopy in people with hip and groin pain.

Our hypothesis was that people with more severe forms of pathology would show significantly poorer PRO and pain scores prior to surgery.

The flow of participant recruitment is outlined in Fig. 1. Briefly, 108 patients underwent assessment for hip and groin pain, of which 87 fulfilled the inclusion criteria and were scheduled for arthroscopy. A total of 73 patients responded to an invitation to participate in the study. Six were excluded because they failed to complete all PRO questionnaires. Sixty-seven patients (45 men) with an average age of 31 years old fulfilled the eligibility criteria, consented to participate and were included in the final study cohort. Fifty-nine of the sixty-seven (88%) participants were serving in the military. The demographic characteristics are summarized in Table 1.

Univariable (crude) association between PROs and hip pathology.

Table 2 presents the univariate associations between PRO subscales and pathology, and demographics. For example, the significant association between severe femoral head chondropathy and the iHot-33-Symptoms subscale suggests that those with severe chondropathy were likely to score 13 points less on this PRO subscale than those without chondropathy. Severe femoral head chondropathy was most highly associated with PRO subscales (POA, iHot-33-Symptoms, iHot-33-QOL, HOOS-Symptoms, HOOS-Pain, HOOS-Sport and HOOS-ADL). Large labral tears also demonstrated a high positive association (POA, iHot-33-Job, HOOS-Symptoms, HOOS-Pain, HOOS-QOL and HOOS-ADL) with sufferers reporting 10–20 points lower on these subscales. Cam and Pincer morphology were associated with the HOOS-Pain and HOOS-Symptoms subscales respectively. Severe acetabular chondropathy was associated with the POA and small labral tears were associated with the HOOS-Pain subscale. Ligamentum teres pathology, mild femoral head chondropathy and mild acetabular chondropathy were not associated with any of the PRO subscales or POA. Fig. 2 presents a scatter-plot of correlations between femoral head chondropathy and score on subscale of HOOS-Symptoms.

Table 2.

Univariable linear regression: crude, unadjusted estimates (regression coefficients 95% CI) of the association between PRO subscales and pathology and demographics.

Outcome (PRO subscale)	Demographics			Diagnosis at arthroscopy
	Age (years)	Gender (female)	Body Mass Index (kg/m2)	Femoral head chondropathya		Acetabular chondropathya		Labrum tearsb		Ligamentum teres pathology	Cam morphology	Pincer morphology
				Mild (grade I–II)	Severe (grade III–IV)	Mild (grade I–II)	Severe (grade III–IV)	Small (1–2 sutures)	Large (3+sutures)
iHOT symptoms and functional limitations	−0.27{−1 to 0.4}	−5.4{−16.6 to 5.8}	−1{−2.3 to 0.2}	−4{−21.9 to 14}	−13.3{−26.4 to −0.3}*	0.8{−13.2 to 14.9}	−4.2{−18.8 to 10.4}	−3.8{−16.9 to 9.3}	−8.9{−21.7 to 4}	−5.7{−30.6 to 19.3}	2.4{−8.6 to 13.4}	−1.6{−13.9 to 10.7}
iHOT sport and recreation	−0.24{−0.9 to 0.4}	−4{−14.8 to 6.8}	−0.7{−1.9 to 0.5}	7.9{−9.7 to 25.4}	−6.4{−19.2 to 6.3}	4.5{−8.9 to 18}	−2{−16 to 12}	−0.03{−12.5 to 12.4}	−9.5{−21.8 to 2.8}	−1.4{−25.4 to 22.6}	−2{−12.5 to 8.6}	−0.5{−12.3 to 11.3}
iHOT job related concerns	0.02{−0.8 to 0.8}	−1{−14.1 to 12}	−1.1{−2.6 to 0.4}	−1.7{−23 to 19.6}	−8.3{−23.8 to 7.2}	−4.5{−20.8 to 11.8}	−3.6{−20.5 to 13.4}	−8.2{−22.6 to 6.2}	−20.1{−34.3 to −6}*	4.5{−24.5 to 33.4}	−6.6{−19.2 to 6}	−7.9{−22 to 6.1}
iHOT social, emotional and lifestyle	0.13{−0.6 to 0.9}	−3.9{−16 to 8.2}	−1{−2.4 to 0.3}	0.33{−19 to 19.7}	−13.4{−27.5 to 0.7}	13{−1.4 to 27.5}	−1.8{−16.8 to 13.2}	4{−10 to 18}	−7.8{−21.5 to 6}	−16{−42.6 to 10.6}	−0.4{−12.3 to 11.4}	0.5{−12.8 to 13.7}
HOOS symptoms and stiffness	−0.19{−0.8 to 0.4}	−0.7{−10 to 8.6}	−1.4{−2.4 to −0.4}*	−3{−17.7 to 11.6}	−12.1{−22.8 to −1.5}*	−1.7{−13.3 to 9.9}	−0.5{−12.7 to 11.6}	−3.5{−14.5 to 7.4}	−9.1{−19.6 to 1.3}	−0.9{−25.8 to 24}	−3{−17.7 to 11.6}	−9.5{−19.5 to 0.6}
HOOS pain	−0.1{−0.7 to 0.4}	−0.8{−9.3 to 7.7}	−0.4{−1.4 to 0.5}	−8.1{−21.4 to 5.2}	−10.6{−20.3 to −0.9}*	1.1{−9.5 to 11.7}	−0.9{−12 to 10.1}	−9.2{−18.9 to 0.5}	−11.2{−20.4 to −1.9}*	−5.1{−27.8 to 17.5}	8.2{0.1 to 16.3}*	−2.4{−11.8 to 7}
HOOS function and ADL	−0.25{−0.8 to 0.3}	−4{−12.9 to 4.9}	−0.52{−1.6 to 0.4}	−9.6{−23.4 to 4.3}	−12.7{−22.8 to −2.6}*	−0.5{−11.7 to 10.6}	−3.5{−15.2 to 8.2}	−7.3{−17.5 to 3}	−12.8{−22.5 to −3}*	−2.5{−26.4 to 21.5}	5.7{−2.9 to 14.4}	−3.6{−13.5 to 6.3}
HOOS sport and recreation	0.21{−0.5 to 1}	2.6{−9 to 14.2}	−1.2{−2.5 to 0.1}	−3.6{−22.2 to 15}	−11.8{−25.3 to 1.8}	1.6{−13 to 16.1}	−1.4{−16.5 to 13.8}	−11.2{−24.9 to 2.5}	−8.8{−21.8 to 4.2}	−7.1{−38.2 to 23.9}	7.7{−3.6 to 19}	−1.4{−11.5 to 14.3}
HOOS quality of life	−0.27{−1 to 0.5}	1.2{−10 to 12.5}	−0.9{−2.2 to 0.4}	−2.3{−20.8 to 16.1}	−0.2{−13.6 to 13.3}	1.3{−12.7 to 15.2}	−4.7{−19.2 to 9.9}	−5.7{−19.5 to 7.5}	−11.4{−24 to 1.2}	−5.4{−35.4 to 24.6}	4.4{−6.6 to 15.4}	−3.6{−16 to 8.8}
Pain on Activity (out of 60)	0.3{−0.2 to 0.8}	0.8{−6.7 to 8.3}	0.1{−0.8 to 1}	7{−4.9 to 18.9}	9.9{1.3 to 18.6}*	2.7{−6.5 to 11.8}	8.9{−0.7 to 18.4}	2{−6.4 to 10.5}	9.9{1.4 to 18.3}*	−2.4{−17 to 12.2}	−0.3{−7.7 to 7}	3.7{−4.5 to 11.9}

a

No chondropathy.

b

No repair.

*

p<0.05.

Note: Values in bold included in multivariable model (p<0.10).

Figure 2.

Scatter-plot of correlations between femoral head chondropathy and score on subscale of HOOS symptoms and stiffness.

(0.06MB).

Most of the study population were classified as having labral pathology (91%) and degrees of acetabular chondropathy (76%). Cam morphology requiring osteoplasty was present in more than half the study population (58%) and the finding of large labral tears (28%) and femoral head chondropathy (31%) were also common, with severe femoral head chondropathy present in 21% of the study population. The strongest association between pathology and PROs was 22% of variability in the HOOS-Symptoms subscale being associated with severe femoral head chondropathy when adjusted for BMI and the presence of pincer morphology. Although the severe femoral head pathology and large labral tears noted during arthroscopy were related to lower scores in pre-operative PROs, their relatively low degree of association refutes the hypothesis that people with more severe pathologies would show significantly poorer PRO and pain scores prior to surgery.

The prevalence of severe femoral head chondropathy in the current study was similar to those reported previously (22%, N=100, mean age=34 years,35 28% of hips younger than 30 years27). However, other studies have reported much lower prevalence, between 7% (grade IV only, N=122, mean age=40.6)36 and 16% (N=2092, mean age=35 years).37 Chondral pathology at time of surgery24 affecting the acetabulum was more commonly reported in those undergoing hip arthroscopy with reported prevalence ranging from 42% (N=595, mean age=38)38 to 97%.35 It is possible that the high percentage of military participants (88%) in this study population affected the high prevalence of severe femoral head chondropathy (21%) and acetabular chondropathy (76%) at a relatively young age (mean=31 years). This may reflect the high mechanical loading associated with military life which also may induce differences in the subjective reporting of disability. It is also worth noting that potential participants with severe degenerative changes evident on imaging were not considered for arthroscopy. This suggests that the routinely used imaging techniques were ineffective at identifying all cases of severe chondropathy and indicates the importance of improved preoperative imaging assessment of cartilage status to help determine the best candidates for hip arthroscopy.10 As the average age of the participants in this study was younger than others referenced,35–37 clinicians should be aware of the high prevalence of severe femoral head chondropathy (21%) and large labral tears (28%) that are not obvious on pre-surgery imaging in relatively-young, military hip pain populations.

At most, only 22% of variability in the HOOS-Symptoms subscale was associated with severe femoral head chondropathy prior to surgery when adjusted for BMI and the presence of pincer morphology. Severe femoral head chondropathy and large labral tears accounted for 15% of the variability in the subscale of Function and ADL (p=0.01) as well as 10% of the POA variability (p=0.04). The subscales most associated with large labral pathology and severe femoral head chondropathy were those with a higher component of movement-related questions, particularly emphasizing hip flexion and extension. Movement questions constitute 83% of the POA and 85% of the HOOS-ADL subscale with the latter over-lapping 5/6 of the POA questions. The HOOS-Symptoms and iHot-33-Symptoms subscales were most associated with severe femoral head chondropathy and contain only 40–60% of questions related to flexion/extension movement. They also contain more questions regarding stiffness, a symptom traditionally associated with OA.39 Large labral tears were associated with the HOOS-Pain and iHot-33-Job subscales which contain 50% and 75% movement related questions respectively. These associations may relate to compression or shearing of the larger labral tears during end of range movement, an act provocative of hip pain symptoms. Milder forms of labral and chondral pathology may be potentially less aggravated by end range hip movement so are not as strongly associated with PROs. The PRO subscales that involve psychological responses (iHot-33-QOL and HOOS-QOL) or higher levels of sports activity (iHot-33-Sport and HOOS-Sport) are least associated with pathology. It is possible that quality of life and sports participation were greatly reduced across all the pre-operative participants, regardless of the severity of pathology, and therefore not associated with distinct pathology types.

The impact of femoral head chondropathy severity on pain and function has been reported in post-operative hip populations.14 Severe chondropathy was associated with worse pain and function at 18 months post surgery14 and had a negative effect on clinical outcome10,11 with grade IV changes on the femoral head deemed unlikely to respond to joint-preserving treatment attempts used in arthroscopy.40 In this study, 10–22% of the variability of the HOOS-Symptoms subscale (p=0.002), HOOS- Function subscale (p=0.01), and the POA (p=0.04) was associated with severe femoral head chondropathy. The greater negative association of severe femoral head chondropathy with symptoms and function PROs concur with the findings of post-operative studies.14 This study found that large labral tears were negatively associated with PRO response for the subscales of iHot-33-Job and HOOS-ADL. Lower scores in the HOOS-Pain subscale were also associated with a combination of small and large labral tears and cam morphology (R2=0.15, p=0.007). Patients with labral tears often have underlying bony anomalies,25 which might explain the relationship with pain.

The pre-operative HOOS-ADL (62.7) and HOOS-Sport (44.4) in this study are similar to those reported by Stake et al.22 (69.9 and 41.9 respectively).22 While PROs give an indication of hip pain and function, they do not measure actual hip functional performance.19 Their usefulness lies in presenting a patient-focused perspective of outcomes important to the patient20 rather than reflecting the extent of intra-articular pathology. In this study, the more severe forms of chondral pathology and large labral tears accounted for up to 22% of the variability in PRO response. This suggests that at least 78% of variability arose from other factors and may benefit from non-surgical management. There is some evidence that risks potentially outweigh the benefits for arthroscopic meniscus debridement in OA knees.41,42 The same may be true of labral debridement and techniques addressing degenerative cartilage change in the hip joint. Patient factors, including mental health,43,44 activity level, sex, and smoking, are more predictive of baseline hip pain (as measured by HOOS) and function than intra-articular findings for FAI sufferers.30 Non-pathological features such as BMI, strength and range of movement may also influence PRO scores. Similar to the knee, non-surgical treatment strategies to address labral tears and OA change may help restore optimal joint mechanics and reduce load on damaged structures.45 Non-surgical interventions may include strengthening hip muscle,46 manual therapy techniques to improve joint range of motion and reduce impingement,47,48 movement retraining, neuromuscular programmes to improve gait biomechanics, and weight control.49

The present study has limitations. There is potential for selection bias. Eighty-eight percent of participants were serving military, an occupation characterized by high levels of physical load, thus limiting external validity of these results. This may have influenced the incidence of severe femoral head chondropathy, large labral tears and the reported reductions in physical capacity. There is some possibility of measurement bias, leading to misclassification or misdiagnosis according to other criteria. For example, diagnosis of FAI and labral lesions was based on the presence and degree of surgical repair determined by the clinical expertise of the treating surgeons. Radiographic measures such as alpha angles, lateral/anterior centre edge angles and Tonnis grade were not used to classify pathology in this study as not all participants underwent imaging compatible with the measurement of these variables and both FAI morphologic features and labral injuries are common in asymptomatic patients.50 Multiple and different combinations of pathologies were present in many of the participants. This may have affected the associations of individual pathologies to patient reported pain and function. There may also have been limitations to the classification of labral tears by the number of sutures used in repair. While size in millimetres and/or clock face location could have been employed, classifying by sutures required for repair provides a practical indication of the extent of the lesion.

Within this population, severe femoral head chondropathy and large labral tears were a relatively common finding during hip arthroscopy and were associated with poorer pre-operative scores on the HOOS-Symptoms and HOOS-ADL subscales, as well as the POA. Movement-related questions make up a high percentage of these subscales. The results of this study are useful to educate hip pain sufferers that degree of pathology seen in arthroscopy or clinical imaging is not necessarily indicative of pain or disability, and that much of the variability in pain and function is explained by other potentially modifiable factors.

The authors certify that they have no affiliations with or financial involvement in any organization or entity with a direct financial interest in the subject matter or materials discussed in the article.

The authors declare no conflicts of interest.