Surgical Correction of Cam Deformity in Association with Femoroacetabular Impingement and Its Impact on the Degenerative Process within the Hip Joint

In Vitro Ovine Cam Impingement Model and Its Effect on Acetabular Cartilage

Background

Femoroacetabular impingement syndrome is a condition where abnormal contact occurs between the femoral head and the acetabulum, leading to chondral damage and hip osteoarthritis. To better understand and treat femoroacetabular impingement syndrome, it is crucial to establish in vitro models that mimic the condition and assess potential interventions.

Purpose

To establish an in vitro ovine cam impingement model and assess the effectiveness of cam excision in reducing the incidence of type 3 acetabular labrum articular disruption (ALAD) (chondral flap) lesions.

Study Design

Controlled laboratory study.

Methods

Utilizing an ovine in vitro cam impingement model, 40 hips were subjected to testing across 5 groups (n = 8 per group): group 1 (control group), 750 N for 200 cycles; group 2 (cycle decrease), 750 N for 100 cycles; group 3 (load decrease), 500 N for 200 cycles; group 4 (cam excision), cam excision followed by 750 N for 200 cycles; and group 5 (halfway cam excision), 750 N for 100 cycles followed by cam excision under an additional 750 N for 100 cycles loading. Each specimen was subsequently assessed for chondral damage according to the ALAD classification, both macroscopically and microscopically.

Results

The control group (group 1) demonstrated the highest ALAD scores (2.7 ± 0.4, 2.8 ± 0.3) compared with other groups, whereas the cam excision group (group 4) exhibited lower scores (0.5 ± 0.5, 0.7 ± 0.4) than both the cycle decrease group (group 2) (1.6 ± 0.5, 1.6 ± 0.5) and the halfway cam excision group (group 5) (1.8 ± 0.6, 2 ± 0.5) (P < .05) in both macroscopic and microscopic gradings (P < .05). The load decrease group (group 3) (1 ± 0.5) also displayed lower scores compared with group 5 (2 ± 0.5) at histological grading (P < .05).

Conclusion

An in vitro sheep model was established that reliably induces mechanical chondrolabral damage in the hip joint. The findings show that reducing the load results in less chondrolabral damage compared with reducing the number of cycles. Furthermore, this model emphasizes the protective effect of cam excision in the management of chondral flap lesions (ALAD type 3).

The critical importance of recognition, evaluation, and management of mental health on outcomes following hip arthroscopy - A synthetic narrative review: Current concepts

Mental health and wellness influence patients with hip pain and dysfunction secondary to Femoroacetabular Impingement Syndrome, acetabular dysplasia, and labral injury. Disorders of mental wellness may impact hip preservation surgery patients both before and after surgery. Major depression and generalized anxiety are the two most common diagnoses that affect hip preservation surgery patients. There are dozens of unique questionnaires that can subjectively and objectively characterize the mental health of patients with hip pain. Pain threshold and pain tolerance are two issues that must be recognized to optimally predict treatment outcome in an informed consent shared decision-making discussion. Patient expectations may also significantly influence preoperative symptoms and postoperative outcome. Pain threshold, pain tolerance, and patient expectations are entities traditionally viewed as qualitative and unmeasurable. However, many valid and reliable methods exist to quantitatively assess these patient-specific variables. Recent original research and synthetic review publications have consistently concluded similar findings: patients with disorders of mental wellness generally have lower preoperative patient-reported outcome scores, do improve following surgery, albeit to a lesser magnitude than non-mental disorder patients, and ultimately have lower postoperative scores at their final follow. As with most orthopaedic surgery literature, the investigation of mental health and hip preservation is primarily via retrospective level four evidence with small numbers of patients from a single centre and single surgeon at short-term follow-up. Although hip preservation surgeons are orthopaedic surgeons by training and practice, they must be able to recognize mental wellness disorders and either treat or refer when suspected or identified.

Surgical Hip Dislocation in the Era of Hip Arthroscopy Demonstrates High Survivorship and Improvements in Patient-reported Outcomes for Complex Femoroacetabular Impingement

BACKGROUND

Over the past decade, hip arthroscopy has become more commonly used in the treatment of patients with femoroacetabular impingement (FAI) as well as those with many other intra-articular hip pathologies. As such, the indications for open surgical hip dislocation have narrowed to include complex intra-articular and extra-articular bony morphologies and revision hip preservation. Although surgical hip dislocation has been established as an effective approach, previous research using contemporary indications has been limited primarily to smaller cohorts with short-term follow-up. Furthermore, factors associated with reoperation, conversion arthroplasty, and not achieving clinical improvement remain ambiguous.

QUESTIONS/PURPOSES

At a minimum of 2 years of follow-up in patients treated for FAI with surgical hip dislocation, (1) how much did patient-reported outcome measures (PROMs) improve, and what percentage of patients achieved the minimum clinically important difference (MCID) and patient-acceptable symptom state (PASS)? (2) What was the survivorship free from reoperation of the hip for any reason? (3) What was the survivorship free from conversion to arthroplasty (THA or hip resurfacing)?

METHODS

Between February 2011 and April 2021, 211 patients were treated at one academic institution with surgical dislocation and osteoplasty of the femoral head-neck junction or greater trochanter for FAI. Of these, patients with concomitant diagnoses including Legg-Calvé-Perthes disease, slipped capital femoral epiphysis, osteochondritis dissecans, a benign tumor, or another neurologic or metabolic disorder were excluded. This yielded 74% (156 of 211) of patients as potentially eligible. A further 12% (18 of 156) of patients without postoperative PROMs were excluded, and another 13% (21 of 156) were lost before the minimum study follow-up of 2 years, leaving 75% (117) for analysis at a median of 4.9 years (range 2 to 12 years) in this retrospective study. A total of 88% of the patients were women (103 of 117), and 40% (47 patients) underwent the procedure as a revision. All patients underwent surgical hip dislocation. Intraoperatively, 66% (77 of 117) of patients demonstrated cam impingement, and the remainder had either pincer impingement or combined cam and pincer; 82% (96 of 117) had some component of extra-articular impingement. To answer our first research question, we obtained PROM scores for the modified Harris hip score (mHHS) and international hip outcome tool 12 (iHOT-12) before surgery and at the most-recent follow-up from our longitudinally maintained institutional database, and we determined the percentage of patients who achieved the MCID or PASS. To answer our second research question, we calculated Kaplan-Meier survivorship free from any reoperation on the hip at 5.8 years (mean follow-up) after the index procedure. To answer our third research question, we calculated the Kaplan-Meier survivorship free from conversion to arthroplasty at 5.8 years. Using univariate logistic regression analysis, factors associated with meeting these defined endpoints were identified.

RESULTS

At a mean of 6 ± 3 years, the mHHS of patients treated with surgical hip dislocation for FAI who had not had previous surgery on the hip improved from 53 ± 15 to 85 ± 13 (mean difference 31 [95% confidence interval 27 to 36]; p < 0.01) and the mean iHOT-12 score improved from 25 ± 14 to 74 ± 24 (mean difference 49 [95% CI 42 to 56]; p < 0.01). At a mean of 5 ± 3 years, for patients with prior hip surgery, mHHS improved from 55 ± 13 to 79 ± 15 (mean difference 24 [95% CI 18 to 30]; p < 0.01) and iHOT-12 scores improved from 25 ± 16 to 66 ± 26 (mean difference 41 [95% CI 31 to 50]; p < 0.01). The proportion of patients who achieved the MCID for the mHHS was 87% (55 of 63) and 83% (33 of 40), while the proportion who achieved the PASS for the mHHS was 66% (46 of 70) and 51% (24 of 47) for primary and revision surgery, respectively. The proportion of patients who achieved the MCID for the iHOT-12 was 87% (53 of 61) and 83% (33 of 40), while the proportion who achieved the PASS for iHOT-12 was 68% (47 of 69) and 57% (26 of 46) for primary and revision surgery, respectively. Higher lateral center-edge angles (odds ratio 1.2 per 1° [95% CI 1.1 to 1.3]; p < 0.01), a lower acetabular version at 2:00 (OR 0.92 per 1° [95% CI 0.85 to 0.99]; p = 0.05), the absence of a labral tear (OR 0.21 [95% CI 0.06 to 0.79]; p = 0.02), a higher preoperative mHHS (OR 1.1 per 1 point [95% CI 1.02 to 1.2]; p < 0.01), and a higher preoperative iHOT-12 score (OR 1.1 per 1 point [95% CI 1.01 to 1.1]; p = 0.01) were associated with not achieving the MCID. In patients without a history of ipsilateral hip surgery, survivorship free from reoperation at 5.8 years after surgical hip dislocation was 90% (95% CI 82% to 98%). In the setting of prior ipsilateral hip surgery, survivorship free from reoperation at 5.8 years after surgical hip dislocation was 75% (95% CI 60% to 95%). No patients for whom surgical hip dislocation was their primary hip procedure underwent conversion to arthroplasty. Among the revision patient cohort, survivorship free from conversion to arthroplasty at 5.8 years after surgical hip dislocation was 97% (95% CI 91% to 100%).

CONCLUSION

Surgical hip dislocation effectively improves hip pain and function with high survivorship (free of reoperation or conversion to arthroplasty) for complex intra-articular and extra-articular FAI that is deemed less suitable for arthroscopic treatment, but when the procedure is used in patients who have had prior hip surgery, they should be told that revision surgery is a realistic possibility. If insufficient acetabular coverage is anticipated, acetabular reorientation osteotomy should be considered. Future studies should evaluate long-term survivorship and PROMs in larger patient cohorts, as well as identify other factors associated with reoperation and conversion to arthroplasty.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The Otto Aufranc Award: Does Hip Arthroscopy at the Time of Periacetabular Osteotomy Improve the Clinical Outcome for the Treatment of Hip Dysplasia? A Multicenter Randomized Clinical Trial

BACKGROUND

A periacetabular osteotomy (PAO) is often sufficient to treat the symptoms and improve quality of life for symptomatic hip dysplasia. However, acetabular cartilage and labral pathologies are very commonly present, and there is a lack of evidence examining the benefits of adjunct arthroscopy to treat these. The goal of this study was to compare the clinical outcome of patients undergoing PAO with and without arthroscopy, with the primary end point being the International Hip Outcome Tool-33 at 1 year.

METHODS

In a multicenter study, 203 patients who had symptomatic hip dysplasia were randomized: 97 patients undergoing an isolated PAO (mean age 27 years [range, 16 to 44]; mean body mass index of 25.1 [range, 18.3 to 37.2]; 86% women) and 91 patients undergoing PAO who had an arthroscopy (mean age 27 years [range, 16 to 49]; mean body mass index of 25.1 [17.5 to 25.1]; 90% women).

RESULTS

At a mean follow-up of 2.3 years (range, 1 to 5), all patients exhibited improvements in their functional score, with no significant differences between PAO plus arthroscopy versus PAO alone at 12 months postsurgery on all scores: preoperative International Hip Outcome Tool-33 score of 31.2 (standard deviation [SD] 16.0) versus 36.4 (SD 15.9), and 12 months postoperative score of 72.4 (SD 23.4) versus 73.7 (SD 22.6). The preoperative Hip disability and Osteoarthritis Outcome pain score was 60.3 (SD 19.6) versus 66.1 (SD 20.0) and 12 months postoperative 88.2 (SD 15.8) versus 88.4 (SD 18.3). The mean preoperative physical health Patient-Reported Outcomes Measurement Information System score was 42.5 (SD 8.0) versus 44.2 (SD 8.8) and 12 months postoperative 48.7 (SD 8.5) versus 52.0 (SD 10.6). There were 4 patients with PAO without arthroscopy who required an arthroscopy later to resolve persistent symptoms, and 1 patient from the PAO plus arthroscopy group required an additional arthroscopy.

CONCLUSIONS

This randomized controlled trial has failed to show any significant clinical benefit in performing hip arthroscopy at the time of the PAO at 1-year follow-up. Longer follow-up will be required to determine if hip arthroscopy provides added value to a PAO for symptomatic hip dysplasia.

A Correspondence-Based Network Approach for Groupwise Analysis of Patient-Specific Spatiotemporal Data

Methods for statistically analyzing patient-specific data that vary both spatially and over time are currently either limited to summary statistics or require elaborate surface registration. We propose a new method, called correspondence-based network analysis, which leverages particle-based shape modeling to establish correspondence across a population and preserve patient-specific measurements and predictions through statistical analysis. Herein, we evaluated this method using three published datasets of the hip describing cortical bone thickness of the proximal femur, cartilage contact stress, and dynamic joint space between control and patient cohorts to evaluate activity- and group-based differences, as applicable, using traditional statistical parametric mapping (SPM) and our proposed spatially considerate correspondence-based network analysis approach. The network approach was insensitive to correspondence density, while the traditional application of SPM showed decreasing area of the region of significance with increasing correspondence density. In comparison to SPM, the network approach identified broader and more connected regions of significance for all three datasets. The correspondence-based network analysis approach identified differences between groups and activities without loss of subject and spatial specificity which could improve clinical interpretation of results.

Imaging of Overuse Injuries of the Hip

Overuse injuries of the hip are common, and clinical diagnosis may be difficult because of overlapping and nonspecific clinical symptoms. Imaging can play an essential role in guiding diagnosis and management. Femoroacetabular joint structural abnormalities result in various conditions that can predispose patients to early development of osteoarthritis. Repetitive stress on the skeletally immature hip can result in apophyseal injuries. Notable nonosseous overuse hip pathologies include athletic pubalgia, trochanteric bursitis, and injuries involving the iliopsoas myotendinous unit. Timely diagnosis of overuse injuries of the hip can facilitate improved response to conservative measures and prevent irreversible damage.

Acetabular cartilage delamination: performance of MRI using arthroscopy as the standard of reference

BACKGROUND

Femoroacetabular impingement (FAI) frequently leads to acetabular chondral delamination. Early identification and treatment of these cases is crucial to prevent further damage to the hip.

PURPOSE

To evaluate the accuracy of morphological signs of cartilage acetabular delamination in non-arthrographic magnetic resonance imaging (MRI) using intra-articular arthroscopic findings in patients undergoing FAI surgery.

MATERIAL AND METHODS

All hip MRI scans were assessed individually by three independent radiologists. Images were assessed for signs of delamination including the presence of a linear area of bright signal intensity along the acetabular subchondral bone and an area of darker tissue at the surface of the acetabular cartilage. All FAI patients underwent surgery; arthroscopy served as the standard of reference.

RESULTS

The mean age of participants was 36.1±10.9 years with 36 (48.6%) women. In the FAI group, arthroscopic surgery showed acetabular chondral delamination in 37 hips. In all hips (including the controls), MRI signs of acetabular cartilage delamination showed an average sensitivity across the three raters of 73.0% with a specificity of 71.0%. In a separate analysis of only the FAI patients, a slightly higher sensitivity (77.7%) but lower specificity (66.7%) was demonstrated. The interrater reliability showed a moderate agreement (average [k]) across the raters (0.450).

CONCLUSION

Performance of non-arthrographic MRI in diagnosing acetabular chondral delamination showed good results, yet inter-observer reproducibility among different radiologists was only moderate. Our results suggest that an increased level of awareness, for signs of delamination using MRI, will be helpful for detecting chondral delamination in patients with a history of FAI.

Ten-year outcome following surgical treatment of femoroacetabular impingement

Aims

The primary aim of this study was to determine the ten-year outcome following surgical treatment for femoroacetabular impingement (FAI). We assessed whether the evolution of practice from open to arthroscopic techniques influenced outcomes and tested whether any patient, radiological, or surgical factors were associated with outcome.

Methods

Prospectively collected data of a consecutive single-surgeon cohort, operated for FAI between January 2005 and January 2015, were retrospectively studied. The cohort comprised 393 hips (365 patients; 71% male (n = 278)), with a mean age of 34.5 years (SD 10.0). Over the study period, techniques evolved from open surgical dislocation (n = 94) to a combined arthroscopy-Hueter technique (HA + Hueter; n = 61) to a pure arthroscopic technique (HA; n = 238). Outcome measures of interest included modes of failures, complications, reoperation, and patient-reported outcome measures (PROMs). Demographic, radiological, and surgical factors were tested for possible association with outcome.

Results

At a mean follow-up of 7.5 years (SD 2.5), there were 43 failures in 38 hips (9.7%), with 35 hips (8.9%) having one failure mode, one hip (0.25%) having two failure modes, and two hips (0.5%) having three failure modes. The five- and ten-year hip joint preservation rates were 94.1% (SD 1.2%; 95% confidence interval (CI) 91.8 to 96.4) and 90.4% (SD 1.7%; 95% CI 87.1 to 93.7), respectively. Inferior survivorship was detected in the surgical dislocation group. Age at surgery, Tönnis grade, cartilage damage, and absence of rim-trimming were associated with improved preservation rates. Only Tönnis grade was an independent predictor of hip preservation. All PROMs improved postoperatively. Factors associated with improvement in PROMs included higher lateral centre-edge and α angles, and lower retroversion index and BMI.

Conclusion

FAI surgery provides lasting improvement in function and a joint preservation rate of 90.4% at ten years. The evolution of practice was not associated with inferior outcome. Since degree of arthritis is the primary predictor of outcome, improved awareness and screening may lead to prompt intervention and better outcomes.

Cite this article: Bone Jt Open 2022;3(10):804–814.

Arthroscopic Acetabular Labral Repair Versus Labral Debridement: Long-term Survivorship and Functional Outcomes

Background:

Arthroscopic treatment for labral tears includes debridement and repair. Long-term studies have failed to demonstrate a difference between these treatments in terms of conversion to total hip arthroplasty (THA).

Purpose:

To investigate 2 different labral treatments, debridement and repair, using an adjusted analysis to evaluate long-term conversion to THA.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This was a retrospective cohort study of patients who underwent hip arthroscopy by a single surgeon between April 2007 and October 2014. Postoperative follow-up information included conversion to THA, patient satisfaction, and patient-reported outcome measures (modified Harris Hip Score; Hip Outcome Score, Activities of Daily Living and Sports Specific subscales; International Hip Outcome Tool; Nonarthritic Hip Score; and Lower Extremity Functional Scale).

Results:

Of the 204 hips included in the study, 99 (48.5%) underwent labral repair, and 105 (51.5%) underwent debridement. In total, 28 (13.7%) of the 204 patients underwent conversion to THA within 10 years after hip arthroscopy (labral repair: 5 [5.0%] vs labral debridement: 23 [21.9%]). Labral repair was associated with a significantly lower risk of conversion to THA compared with debridement (hazard ratio [HR] = 0.24; 95% CI, 0.07-0.74; P = .014). Additional factors associated with risk of conversion to THA included older age at the time of arthroscopy (HR = 1.06 per year; 95% CI, 1.02-1.11; P = .002) and Tönnis grade (HR = 2.39; CI, 1.14-5.41; P = .026). Abrasion chondroplasty, acetabuloplasty, body mass index, Outerbridge grade, and radiographic femoroacetabular impingement were not found to be significantly associated with risk of THA. No significant difference in patient satisfaction was found between treatment groups, and for patients who did not convert to THA, there was no difference in mean patient-reported outcome scores at final follow-up.

Conclusion:

Patients who underwent labral repair were less likely to convert to THA compared with patients who underwent labral debridement, despite adjustment for differences in baseline patient characteristics and preexisting pathology. Additional factors associated with a lower rate of hip survival were older age and osteoarthritis at the time of hip arthroscopy.

A Novel Model of Hip Femoroacetabular Impingement in Immature Rabbits Reproduces the Distinctive Head-Neck Cam Deformity

BACKGROUND

Femoroacetabular impingement (FAI) is a leading cause of hip pain in young adults and often leads to degenerative osteoarthritis (OA). A small animal model of hip deformities is crucial for unraveling the pathophysiology of hip OA secondary to FAI.

PURPOSES

To (1) characterize a new minimally invasive surgical technique to create a proximal femoral head-neck deformity in a skeletally immature rabbit model and (2) document the effect of an injury to the medial proximal femoral epiphysis on head-neck morphology at 28 days after the injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six-week-old New Zealand White rabbits (n = 10) were subjected to right hip surgery, with the left hip used as a control. An epiphyseal injury in the medial femoral head was created using a 1.6-mm drill. Hips were harvested bilaterally at 28 days after surgery. Alpha and epiphyseal shaft angles were measured on radiographs. Alpha angles at the 1- and 3-o'clock positions were measured on the oblique axial plane of micro-computed tomography images. Bone bar formation secondary to growth plate injuries was confirmed using alcian blue hematoxylin staining.

RESULTS

All hips in the study group showed a varus-type head-neck deformity, with lower epiphyseal shaft angles on anteroposterior radiographs versus those in the control group (133°± 8° vs 142°± 5°, respectively; P = .022) and higher epiphyseal shaft angles on lateral radiographs (27°± 12° vs 10°± 7°, respectively; P < .001). The mean alpha angles in the study group were higher at both the 1- (103°± 14° vs 46°± 7°, respectively; P < .002) and 3-o'clock (99°± 18° vs 35°± 11°, respectively; P < .002) positions than those in the control group. Alcian blue hematoxylin staining of all hips in the study group indicated that the injured physis developed a bony bar, leading to growth plate arrest on the medial femoral head.

CONCLUSION

The proposed model led to growth arrest at the proximal femoral physis, resulting in a femoral head-neck deformity similar to human FAI.

CLINICAL RELEVANCE

Our novel small animal model of a femoral head-neck deformity is a potential platform for research into the basic mechanisms of FAI disease progression and the development of disease-modifying therapies.

Effect of posture and femoral neck osteochondroplasty on femur-acetabulum clearance in patients with cam-type femoroacetabular impingement

It is not clear whether femoral neck osteochondroplasty achieves its objective of increasing femoroacetabular clearance. We used an upright open magnetic resonance imaging scanner to image the hip joint in multiple postures to explore the effect of posture and femoral neck osteochondroplasty on femur-acetabulum clearance in patients with cam-type femoroacetabular impingement. We recruited 13 consecutive patients scheduled to undergo arthroscopic femoral neck osteochondroplasty and completed assessments on 10 patients. We scanned each subject before surgery and at 6 months post-op in supine and 3 other physiological postures: supine 90° flexion with adduction and internal rotation (FADIR), sitting deep (maximal flexion with internal rotation and adduction), and sitting crossed leg (maximal adduction with flexion and internal rotation). We measured the alpha angle, which describes the severity of cam deformity, and the beta angle, which defines joint clearance. We also evaluated hip flexion, internal rotation, and adduction before and after surgery. Femoral neck osteochondroplasty significantly decreased alpha angle by 23.9° ± 4.6° (p = 0.001) and increased beta angle across all postures by 28.1° ± 6.3° (p = 0.002). An increase in beta angle represented a decreased chance of impingement. Femoral neck osteochondroplasty significantly increased flexion by an average of 8.6° in the sitting deep posture after surgery (p = 0.007) which might indicate an improvement of joint function. These findings lend support to the hypothesis that arthroscopic osteochondroplasty accomplishes its stated goals of increasing bone-bone clearance in the hip joint and improving joint mechanics for the static postures assessed.

Pre- and postoperative in silico biomechanics in individuals with cam morphology during stair tasks

BACKGROUND

Osteochondroplasty for cam femoroacetabular impingement is a common treatment to improve hip function and prevent joint degeneration. The purpose was to compare in-silico hip biomechanics during stair tasks in pre- and postoperative patients matched with healthy controls.

METHODS

Ten symptomatic cam femoroacetabular impingement patients performed stair ascent and descent pre- and 2 years postoperatively. Patients were age, and body-mass-index matched to controls. Full-body kinematics and kinetics were computed and, muscle and hip contact forces were estimated using musculoskeletal modeling and static optimization. Stance-phases were time-normalized and compared using statistical non-parametric mapping.

FINDINGS

Preoperatives showed lower hip abduction than controls during stairs ascent (76-100%, P = .007). Pre- and postoperative showed lower hip external rotation compared to controls on stair ascent (Pre-op vs controls: 71-100%, P = .005; Post-op vs controls: 72-100%, P = .01) and stair descent (Pre-op vs controls: 0-62%, P = .001; Post-op vs controls: 0-60%, P = .001). Postoperatives showed lower iliacus force compared to preoperative (1-3%, P = .012) and control (3-6%, P = .008), and higher gluteus maximus and piriformis forces compared to controls during stair descent. Lower postoperative anterior hip contact force (0-7%, P = .004) during descent, and superior (33-35%, P = .018) during ascent compared to controls were observed. Postoperative contact forces were medialized compared to preoperative (0-2%, P = .011) and controls (1-2%, P = .016).

INTERPRETATION

Forcing participants to adhere to standardized step length/rise minimized sagittal kinematic differences between conditions and groups. Persistent reduced hip external rotation postoperatively and minor muscle force adaptations led to reduced superior hip contact force during stair ascent and reduced anterior and more medialized contact forces during stair descent.

What Is the Correlation Among dGEMRIC, T1p, and T2* Quantitative MRI Cartilage Mapping Techniques in Developmental Hip Dysplasia?

BACKGROUND

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is a validated technique for evaluating cartilage health in developmental dysplasia of the hip (DDH), which can be a helpful prognosticator for the response to surgical treatments. dGEMRIC requires intravenous injection of gadolinium contrast, however, which adds time, expense, and possible adverse reactions to the imaging procedure. Newer MRI cartilage mapping techniques such as T1 rho (ρ) and T2* have been performed in the hip without the need for any contrast, although it is unknown whether they are equivalent to dGEMRIC.

QUESTION/PURPOSE

In this study, our purpose was to determine the correlation between the relaxation values of three cartilage mapping techniques, dGEMRIC, T1ρ, and T2*, in patients with DDH.

METHODS

Fifteen patients with DDH (three male, 12 female; mean age 29 ± 9 years) scheduled for periacetabular osteotomy underwent preoperative dGEMRIC, T1ρ, and T2* MRI at 3T with quantitative cartilage mapping. The outcomes of dGEMRIC, T1ρ, and T2* mapping were calculated for three regions of interest (ROI) to analyze the weightbearing cartilage of the hip: global ROI, anterior and posterior ROI, and further subdivided into medial, intermediate, and lateral to generate six smaller ROIs. The correlation between the respective relaxation time values was evaluated using the Spearman correlation coefficient (rS) for each ROI, categorized as negligible, weak, moderate, strong, or very strong. The relaxation values within the subdivided ROIs were compared for each of the three cartilage mapping techniques using the Kruskal-Wallis test.

RESULTS

There was a moderate correlation of T1ρ and T2* relaxation values with dGEMRIC relaxation values. For the global ROI, there was a moderate correlation between dGEMRIC and T2* (moderate; rS = 0.63; p = 0.01). For the anterior ROI, a moderate or strong correlation was found between dGEMRIC and both T1ρ and T2*: dGEMRIC and T1ρ (strong; rS = -0.71; p = 0.003) and dGEMRIC and T2* (moderate; rS = 0.69; p = 0.004). There were no correlations for the posterior ROI. The mean dGEMRIC, T1ρ, and T2* relaxation values were not different between the anterior and posterior ROIs nor between the subdivided six ROIs.

CONCLUSION

Quantitative T1ρ and T2* cartilage mapping demonstrated a moderate correlation with dGEMRIC, anteriorly and globally, respectively. However, the clinical relevance of such a correlation remains unclear. Further research investigating the correlation of these two noncontrast techniques with clinical function and outcome scores is needed before broad implementation in the preoperative investigation of DDH.

LEVEL OF EVIDENCE

Level II, diagnostic study.

Evaluation of outcome reporting trends for femoroacetabular impingement syndrome- a systematic review

PURPOSE

The aim of this systematic review was to evaluate the trends in the literature regarding surgical treatment for femoroacetabular impingement syndrome (FAIS) and to present which patient-reported outcome-measures (PROMs) and surgical approaches are included.

METHODS

This systematic review was conducted with the PRISMA guidelines. The literature search was performed on PubMed and Embase, covering studies from 1999 to 2020. Inclusion criteria were clinical studies with surgical treatment for FAIS, the use of PROMs as evaluation tool and studies in English. Exclusion criteria were studies with patients < 18 years, cohorts with < 8 patients, studies with primarily purpose to evaluate other diagnoses than FAIS and studies with radiographs as only outcomes without using PROMs. Data extracted were author, year, surgical intervention, type of study, level of evidence, demographics of included patients, and PROMs.

RESULTS

The initial search yielded 2,559 studies, of which 196 were included. There was an increase of 2,043% in the number of studies from the first to the last five years (2004-2008)-(2016-2020). There were 135 (69%) retrospective, 55 (28%) prospective and 6 (3%) Randomized Controlled Trials. Level of evidence ranged from I-IV where Level III was most common (44%). More than half of the studies (58%) originated from USA. Arthroscopic surgery was the most common surgical treatment (85%). Mean follow-up was 27.0 months (± 17 SD), (range 1.5-120 months). Between 1-10 PROMs were included, and the modified Harris Hip Score (mHHS) was most commonly used (61%).

CONCLUSION

There has been a continuous increase in the number of published studies regarding FAIS with the majority evaluating arthroscopic surgery. The mHHS remains being the most commonly used PROM.

Surgical Treatment of Labral Tears: Debridement, Repair, and Reconstruction

Advances in hip preservation surgery have to lead to increased utilization of hip arthroscopy. With this, there has also been a growth in the understanding of various hip conditions, therefore, leading to an increase in hip conditions amenable to arthroscopic intervention. The acetabular hip labrum has been at the forefront of arthroscopic advances in the hip. The labrum is important for hip stability, provision of the suction seal, and joint proprioception. Given the labrum's central role in hip biomechanics, there is increasing emphasis on labral preservation in the form of debridement and repair. In revision settings, advanced techniques such as labral augmentation and reconstruction may play a role in the management of labral pathology. Appropriate management of the hip labrum at the time of surgery can be an important mediator of the outcome. As such, an understanding of the evolving evidence base and surgical indications and techniques are integral to the treatment and management of labral pathology.

Insurance Coverage Criteria for Femoroacetabular Impingement Surgery: Are They Responding to Improving Evidence?

BACKGROUND

With the rapidly growing body of FAI literature in the last decade, improved evidence exists to support FAI surgery. However, it remains unclear how well third-party insurance company's FAI policies have adapted over time to improved evidence. The purpose of this study was (1) to compare the 2020 FAI surgery criteria of four major insurance companies utilizing a multi-center cohort of FAI patients undergoing surgery to identify rates and causes of ineligibility, and (2) to compare the rates of approval based on changes in policy from 2012 to 2020.

METHODS

Four major insurance companies' coverage policies with specific criteria for the surgical treatment of FAI were applied to this population at two time points (2012 and 2020). The policies listed various combinations of age, symptom duration, radiographic signs of FAI, radiographic signs of osteoarthritis, and physical exam findings. A prospective, multi-center cohort of 712 patients (including 45.5% males and 54.5% females with a mean age of 28.7 years) undergoing surgical treatment of FAI was utilized for analysis of insurance policies.

RESULTS

Based on 2020 FAI policies across 4 insurers, 22.5% (range 18.4-28.4%) of FAI patients would be deemed ineligible. In 2012, the average percent exclusion of the four companies was 23.7%. The most likely reason to be excluded was either failure to meet imaging criteria (alpha angle >50° or positive cross-over sign) [13%, n=94]) or the absence of an impingement sign (9%, n=65). Other causes of exclusion were <6-month symptom duration (6%, n=44), age <15 years (4%, n=28), or skeletally immaturity (3%, n=23).

CONCLUSION

Our study shows that despite a six-year span of growing literature and updated policies, nearly 1 in 5 patients diagnosed with FAI would still potentially be denied coverage. This highlights a continued divide between surgeons and insurance companies. There is a major need for improved consensus regarding the diagnosis of FAI and appropriate indications for surgical intervention.Level of Evidence: IV.

Hip arthroscopy for lateral cam morphology: how important are the vessels?

The purpose of this narrative review is to identify the anatomy and relevant blood supply to the femoral head as it pertains to hip arthroscopy and lateral cam morphology. The primary blood supply to the femoral head is the lateral ascending superior retinacular vessels, which are terminal branches of the medial femoral circumflex artery. These vessels penetrate the femoral head at the posterolateral head–neck junction. Surgeons performing posterolateral femoral osteoplasty must respect this vasculature to avoid iatrogenic avascular necrosis (AVN). Avoidance of excessive traction, avoidance of distal posterolateral capsulotomy and avoidance of disruption of the superior retinacular vessels should keep the risk for AVN low. Hip extension, internal rotation and distraction are useful in hip arthroscopy to better visualize lateral/posterolateral cam morphology to facilitate an accurate comprehensive cam correction and avoid vascular disruption.

Hip Muscle Forces and Contact Loading During Squatting After Cam-Type FAI Surgery

BACKGROUND

The purpose of this study was to compare muscle forces and hip contact forces (HCFs) during squatting in patients with cam-type femoroacetabular impingement (cam-FAI) before and after hip corrective surgery and with healthy control participants.

METHODS

Ten symptomatic male patients with cam-FAI performed deep squatting preoperatively and at 2 years postoperatively. Patients were matched by age and body mass index to 10 male control participants. Full-body kinematics and kinetics were computed, and muscle forces and HCFs were estimated using a musculoskeletal model and static optimization. Normalized squat cycle (%SC) trials were compared using statistical nonparametric mapping (SnPM).

RESULTS

Postoperatively, patients with cam-FAI squatted down with higher anterior pelvic tilt, higher hip flexion, and greater hip extension moments than preoperatively. Preoperative patients demonstrated lower anterior pelvic tilt and lower hip flexion compared with the participants in the control group. Postoperative patients showed increased semimembranosus force compared with their preoperative values. Preoperative forces were lower than the control group for the adductor magnus, the psoas major, and the semimembranosus; however, the preoperative patients showed greater inferior gluteus maximus forces than the patients in the control group, whereas the postoperative patients did not differ from the control patients. Higher posterior, superior, and resultant HCF magnitudes were identified postoperatively in comparison with the preoperative values. Preoperative posterior HCF was lower than in the control group, whereas the postoperative posterior HCF did not differ from those in the control group.

CONCLUSIONS

Higher postoperative anterior pelvic tilt was associated with an indication of return to closer to normal pelvic motion, which resembled data from the control group. Lower preoperative anterior pelvic tilt was associated with muscle force imbalance, indicated by decreased semimembranosus and increased gluteus maximus forces. The overall increased postoperative muscle forces were associated with improved pelvic mobility and increased HCFs that were comparable with the control-group standards.

CLINICAL RELEVANCE

Muscle forces and HCFs may be indicative of postoperative joint health restoration and alleviated symptoms.

Surgical Treatment of Femoroacetabular Impingement: Hip Arthroscopy Versus Surgical Hip Dislocation: A Propensity-Matched Analysis

BACKGROUND

Surgical treatment of femoroacetabular impingement (FAI) continues to evolve and is most commonly approached with either hip arthroscopy (HA) or surgical dislocation (SD) of the hip. The purpose of this study was to compare the outcomes of similar patients undergoing surgical treatment of FAI with either HA or SD.

METHODS

A prospective multicenter cohort study of patients undergoing primary surgical treatment of FAI was performed. Follow-up at a minimum of 1 year (mean, 4.3 years) was available for 621 hips (81.7%), including 399 procedures with HA and 222 procedures with SD. Propensity scores were calculated and reflect the likelihood of surgical treatment with HA versus SD for a given set of covariates. Propensity scores allowed 1:1 matching to identify similar patients at baseline. After propensity matching, 128 matched pairs of patients who underwent HA and 128 matched pairs of those who underwent SD were included in the study. The primary outcome was the postoperative modified Harris hip score (mHHS); secondary outcomes included the Hip disability and Osteoarthritis Outcome Score (HOOS), the University of California Los Angeles (UCLA) activity score, and the Short Form-12 (SF-12) physical and mental subscores, as well as the rate of persistent symptoms, revision surgery, and total hip arthroplasty (THA).

RESULTS

After propensity matching, the 2 groups exhibited similar distributions of all of the covariates that were included in the model. Both groups demonstrated significant improvements in all patient-reported outcomes (PROs). The final mHHS was not significantly different between the 2 matched groups (81.3 for the HA group versus 80.2 for the SD group, p = 0.67). Likewise, the HOOS pain subscale was similar at the time of final follow-up (77.6 versus 80.5, respectively, p = 0.32). No difference between the HA group and the SD group was identified in the rate of THA (0% and 3.1%, respectively, p = 0.41) and revision surgery (7.8% and 10.9%, respectively, p = 0.35); overall rates of persistent symptoms were 21.9% for the HA group and 24.4% for the SD group (p = 0.55).

CONCLUSIONS

In a propensity-matched analysis of patients who were treated with either approach, patients undergoing HA or SD demonstrated similar outcomes at a mean of 4 years postoperatively.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Risk Factors for Conversion of Hip Arthroscopy to Total Hip Arthroplasty: A Large Closed-Cohort Study

Purpose

To evaluate risk factors for conversion of hip arthroscopy to total hip arthroplasty (THA) within 2 years in a closed patient cohort.

Methods

This study was a case series of consecutive hip arthroscopy procedures from September 2008 to November 2018 in the electronic medical record of Kaiser Permanente Northern California. Patients were included with minimum 2-year follow-up or if they had conversion to THA within 2 years (the primary outcome) regardless of follow-up time. Patient characteristics at the time of the index arthroscopy were extracted; characteristics of patients who experienced the outcome event versus those who did not were compared by use of multivariable logistic regression models and receiver operating characteristic (ROC) curves.

Results

The mean follow-up time was 4.9 years (median 4.6, range 0.6 to 11.6). The mean age was 37.2 years (range 10 to 88), and 57% were female. During the follow-up period, 82 patients underwent a THA within 2 years of their arthroscopies (5.3%, 95% confidence interval 4.3% to 6.5%) after a median time of 9 months (interquartile range 5.9 to 14.4) after the initial arthroscopy. Increasing age was highly predictive of early THA conversion (area under the ROC curve = 0.78, P < .001). Although other predictors showed significant bivariable associations with early failure, body mass index (BMI), race, sex, and prior arthroscopy did not add meaningful independent predictive information.

Conclusions

The risk of conversion to THA within 2 years after hip arthroscopy increased substantially with patient age at the time of the procedure. BMI, race, sex, and prior arthroscopy were not important independent predictors of conversion beyond the information contained in patient age.

Level of Evidence

Level IV, therapeutic case series.

Periacetabular osteotomy with or without arthroscopic management in patients with hip dysplasia: study protocol for a multicenter randomized controlled trial

Background

Hip dysplasia is one of the most common causes of hip arthritis. Its incidence is estimated to be between 3.6 and 12.8% (Canadian Institute for Health Information, Hip and knee replacements in Canada, 2017–2018: Canadian joint replacement registry annual report, 2019; Jacobsen and Sonne-Holm, Rheumatology 44:211–8, 2004). The Periacetabular Osteotomy (PAO) has been used successfully for over 30 years (Gosvig et al., J Bone Joint Surg Am 92:1162–9, 2010), but some patients continue to exhibit symptoms post-surgery (Wyles et al., Clin Orthop Relat Res 475:336–50, 2017). A hip arthroscopy, performed using a small camera, allows surgeons to address torn cartilage inside the hip joint. Although both procedures are considered standard of care treatment options, it is unknown whether the addition of hip arthroscopy improves patient outcomes compared to a PAO alone. To delay or prevent future joint replacement surgeries, joint preservation surgery is recommended for eligible patients. While previous studies found an added cost to perform hip arthroscopies, the cost-effectiveness to Canadian Health care system is not known.

Methods

Patients randomized to the experimental group will undergo central compartment hip arthroscopy prior to completion of the PAO. Patients randomized to the control group will undergo isolated PAO. Patient-reported quality of life will be the primary outcome used for comparison between the two treatment groups as measured by The International Hip Outcome Tool (iHOT-33) (Saberi Hosnijeh et al., Arthritis Rheum 69:86–93, 2017). Secondary outcomes will include the four-square step test and sit-to-stand (validated in patients with pre-arthritic hip pain) and hip-specific symptoms and impairment using the HOOS; global health assessment will be compared using the PROMIS Global 10 Score; health status will be assessed using the EQ-5D-5L and EQ VAS questionnaires (Ganz et al., Clin Orthop Relat Res 466:264–72, 2008) pre- and post-operatively. In addition, operative time, hospital length of stay, adverse events, and health services utilization will be collected. A sub-group of patients (26 in each group) will receive a T1rho MRI before and after surgery to study changes in cartilage quality over time. A cost-utility analysis will be performed to compare costs and quality-adjusted life years (QALYs) associated with the intervention.

Discussion

We hypothesize that (1) concomitant hip arthroscopy at the time of PAO to address central compartment pathology will result in clinically important improvements in patient-reported outcome measures (PROMs) versus PAO alone, that (2) additional costs associated with hip arthroscopy will be offset by greater clinical improvements in this group, and that (3) combined hip arthroscopy and PAO will prove to be a cost-effective procedure.

Trial registration

ClinicalTrials.gov NCT03481010. Registered on 6 March 2020. Protocol version: version 3.

Running with Femoral Acetabular Impingement: Operative Vs Nonoperative Treatment

A 31-year-old female lawyer presents with right hip pain starting approximately 3 years ago and worsening over the past 2 to 3 months. She is an avid runner, running 20 to 30 miles weekly, and noticed that her pain started after a running program training for the marathon. Her pain is primarily over the lateral aspect of her hip with some radiation into the groin. The pain is made worse with impact exercises such as running and made better with walking and cycling. She has done physical therapy for the past 3 months without any significant improvement. She has not had any injections or taken anti-inflammatories because of a history of gastric ulcer disease. On physical examination she has mild tenderness over her right greater trochanter and her range of motion tests are full in terms of flexion, internal rotation, and external rotation. She has a positive FADIR (flexion-adduction-internal rotation) impingement that causes both groin and lateral hip pain. Radiograph of the right hip revealed preservation of the joint space and an anterior cam lesion with reduced offset at the femoral head neck junction. Magnetic resonance imaging (MRI) of the right hip revealed a tear at the anterior superior labrum at the 1 to 2 o'clock position along with subjacent bone marrow edema in the femoral head that is likely reactive. Computed tomography (CT) scan of the right hip confirmed a combined cam and pincer type femoral acetabular impingement of the right hip with overcoverage of the femoral head. There was 15° of femoral anteversion and the coronal lateral center of edge angle (LCEA) is 34°. Dr. Peter Moley argues that a focused rehabilitation program to restore strength and motor control of the deep hip stabilizers will provide optimal functional recovery. Dr. Jakub Tatka argues that right hip arthroscopy with labral repair and possible osteochondralplasty are indicated in order to prevent early hip arthritis and prevent long-term sequela of femoral acetabular impingement.

Inflammatory Response of Articular Cartilage to Femoroacetabular Impingement in the Hip

BACKGROUND

Femoroacetabular impingement (FAI) has been proposed as an etiologic factor in up to 50% of hips with osteoarthritis (OA). Inflammation is thought to be one of the main initiators of OA, yet little is known about the origin of intra-articular inflammation in FAI hips.

HYPOTHESIS

Articular cartilage from the impingement zone of patients with FAI has high levels of inflammation, reflecting initial inflammatory process in the hip.

STUDY DESIGN

Controlled laboratory study.

METHODS

Head-neck cartilage samples were obtained from patients with cam FAI (cam FAI, early FAI; n = 15), advanced OA secondary to cam FAI (FAI OA, late FAI; n = 15), and advanced OA secondary to developmental dysplasia of the hip (DDH OA, no impingement; n = 15). Cartilage procured from young adult donors (n = 7) served as control. Safranin O-stained sections were assessed for cartilage abnormality. Tissue viability was detected by TUNEL assay. Immunostaining of interleukin 1β (IL-1β), catabolic markers (matrix metalloproteinase 13 [MMP-13], a disintegrin and metalloproteinase with thrombospondin motif 4 [ADAMTS-4], aggrecan antibody to C-terminal neoepitope [NITEGE]), and an anabolic marker (type II collagen [COL2]) was performed to evaluate molecular inflammation and metabolic activity. The average percentage of immunopositive cells from the total cell count was calculated. Kruskal-Wallis test followed by Steel-Dwass post hoc test was used for multiple comparisons.

RESULTS

Microscopic osteoarthritic changes were more prevalent in cartilage of cam FAI and FAI OA groups compared with DDH OA and control groups. Cartilage in cam FAI and FAI OA groups, versus the DDH group, had higher expression of inflammatory molecules IL-1β (69.7% ± 18.1% and 72.5% ± 13.2% vs 32.7% ± 14.4%, respectively), MMP-13 (79.6% ± 12.6% and 71.4% ± 18.8% vs 38. 5% ± 13.3%), ADAMTS-4 (83.9% ± 12.2% and 82.6% ± 12.5% vs 45.7% ± 15.5%), and COL2 (93.6% ± 3.9% and 92.5% ± 5.8% vs 53.3% ± 21.0%) (P < .001). Expression of NITEGE was similar among groups (cam FAI, 89.7% ± 7.7%; FAI OA, 95.7% ± 4.7%; DDH OA, 93.9% ± 5.2%; P = .0742). The control group had minimal expression of inflammatory markers. Inflammatory markers were expressed in all cartilage zones of early and late FAI but only in the superficial zone of the no impingement group.

CONCLUSION

Cartilage from the impingement zone in FAI is associated with a high expression of inflammatory markers, extending throughout all cartilage zones.

CLINICAL RELEVANCE

Inflammation associated with FAI likely has a deleterious effect on joint homeostasis. Further clinical and translational studies are warranted to assess whether and how surgical treatment of FAI reduces molecular inflammation.

Editorial Commentary: Hip Preservation and Opioids

Approximately one-third of patients undergoing arthroscopic hip preservation surgery for femoroacetabular impingement syndrome and labral tears are on preoperative opioid medications. The single most important predictor for prolonged chronic postoperative opioid use is preoperative use. Despite the well-documented high success rates in nonarthritic, nondysplastic individuals undergoing hip arthroscopy, up to half of those individuals on preoperative opioids may still be on opioids at 1 to 2 years of follow-up. Mental wellness disorders (e.g., depression, anxiety, substance abuse) significantly impact both pre- and postoperative pain, function, and activity in nearly all joint and general health outcome measures. Multimodal pain management strategies have shown excellent reduction in perioperative opioid utilization. Intraoperative techniques should strive for comprehensive true hip preservation: labral repair, accurate cam/pincer morphology correction, and routine capsular management. Objective, quantitative pain threshold and pain tolerance measurements may improve treatment decision-making, with better prediction of surgical outcomes. Future personalized health care may use a single individual's mu opioid receptor (OPRM-1 gene) and a number of other genetic markers for pain management to reduce the need for traditional opioid medications. Is opioid-free hip arthroscopy possible? Absolutely. Will the opioid epidemic end? Yes, but we have a lot of work to do.

Editorial Commentary: The Wild, Wild West of Hip Arthroscopy-When to Pull the Trigger?

In our continued effort to refine the treatment algorithm of femoroacetabular impingement syndrome, duration of symptoms before surgery is receiving considerable attention by researchers. A (somewhat) negative linear correlation is being elucidated between outcomes and extent of damage at time of arthroscopy. Knowing this, it may be prudent in certain patient populations to recommend surgery earlier in the disease process in hopes of minimizing the amount of damage to the joint to delay or avoid the onset of arthritis.

Full recovery of hip muscle strength is not achieved at return to sports in patients with femoroacetabular impingement surgery

PURPOSE

The purpose of this study was to study dynamic hip  external rotation strength in patients with Femoroacetabular impingement surgery (FAI) syndrome who have undergone unilateral arthroscopic treatment and returned to sports.

METHODS

A cross-sectional study was performed using an observational group (n = 22) and a matched control group (n = 22). Dynamic external rotation strength of the hip was measured using the Augustsson Strength Test, which has shown high reliability for examining side-to-side differences in hip muscle strength.

RESULTS

Dynamic hip external rotation strength was significantly lower in the arthroscopically treated hip compared with the non-treated hip within the observational group (p < 0.004).

CONCLUSION

This cross-sectional study shows that at return to sports, patients who have undergone unilateral arthroscopic treatment for FAI syndrome do not have adequate hip muscle strength recovery. Rehabilitation protocols should, therefore, emphasise post-operative strength training of the hip muscles. Additional research is needed to determine the consequences of reduced hip strength for the long-term outcome after arthroscopically treated FAI.

CLINICAL RELEVANCE

The results of this study underline the importance of post-operative strength training prior to returning to sports in patients with femoroacetabular impingement surgery.

LEVEL OF EVIDENCE

III.

Short term outcomes of hip arthroscopy on hip joint mechanics and cartilage health in patients with femoroacetabular impingement syndrome

BACKGROUND

Femoroacetabular acetabular impingement syndrome consists of abnormal hip joint morphology resulting in painful hip joint impingement. Hip arthroscopy corrects the abnormal morphology and reduces clinical symptoms associated with femoroacetabular impingement syndrome yet the effects of hip arthroscopy on gait mechanics and cartilage health are not well understood.

METHODS

Ten femoroacetabular impingement syndrome patients and 10 matched asymptomatic controls underwent gait analysis consisting of three-dimensional hip joint kinematics and kinetics. Femoroacetabular impingement syndrome patients underwent gait analysis and quantitative magnetic resonance imaging of the surgical hip joint before and seven months post-surgery. Patient reported outcomes were obtained from all study participants and were used to quantify hip joint pain, function and quality of life.

FINDINGS

Prior to surgery, femoroacetabular impingement syndrome patients demonstrated hip joint kinematics or kinetics as the control group. After surgery, femoroacetabular impingement syndrome patients exhibited improved patient reported outcomes, similar hip joint kinematic patterns, increased hip flexion and decreased hip extension moment impulses within the surgical limb. The femoroacetabular impingement syndrome patients that ambulated with increased HFMI post-surgery demonstrated a decrease in femoral cartilage T1ρ and T2 values.

INTERPRETATION

Femoroacetabular impingement syndrome patients exhibited improved clinical symptoms yet ambulated with altered sagittal plane hip joint loading after hip arthroscopy. Increased hip flexion moment impulse post-surgery was associated with improved cartilage health within the surgical limb. These study findings suggest that sagittal plane hip joint loading at short-term follow-up after hip arthroscopy is associated with cartilage health and may be an important biomechanical parameter in post-operative rehabilitation programs.

Hip Joint Capsular Anatomy, Mechanics, and Surgical Management

➤Hip joint capsular ligaments (iliofemoral, ischiofemoral, and pubofemoral) play a predominant role in functional mobility and joint stability. ➤The zona orbicularis resists joint distraction (during neutral positions), and its aperture mechanism stabilizes the hip from adverse edge-loading (during extreme hip flexion-extension). ➤To preserve joint function and stability, it is important to minimize capsulotomy size and avoid disrupting the zona orbicularis, preserve the femoral head size and neck length, and only repair when or as necessary without altering capsular tensions. ➤It is not fully understood what the role of capsular tightness is in patients who have cam femoroacetabular impingement and if partial capsular release could be beneficial and/or therapeutic. ➤During arthroplasty surgery, a femoral head implant that is nearly equivalent to the native head size with an optimal neck-length offset can optimize capsular tension and decrease dislocation risk where an intact posterior hip capsule plays a critical role in maintaining hip stability.

Surgical Treatment of Labral Tears: Debridement, Repair, Reconstruction

PURPOSE OF REVIEW

With the rapid growth of hip arthroscopy over the past decade, new treatment paradigms as well as recognition of new disease states have sprung forth. The ability to perform complex arthroscopic procedures of the hip such as labral augmentation and reconstruction is essential for hip arthroscopists in the revision setting, with patient selection and indications for various labral treatments the key driver for improved short- and mid-term clinical outcomes.

RECENT FINDINGS

Current techniques have been developed to address disease states where the labrum is either unstable, torn, deficient, or otherwise incompetent. Many early reports focused on the description of these techniques with new literature reporting short- and mid-term outcomes. A few of these have demonstrated improved outcomes with a contemporary arthroscopy with emphasis on capsule preservation and repair. Studies have demonstrated that labral repair has improved outcomes over labral debridement, with results of labral reconstruction in a revision approaching those of labral repair. In addition, newer reports have shown significantly improved outcomes and survivorship with capsule repair and therefore should be included in every hip arthroscopy.

Outcomes for Surgical Treatment of Femoroacetabular Impingement in Adults

PURPOSE OF REVIEW

To assess the outcomes of modern techniques for arthroscopic surgery in the treatment of femoroacetabular impingement.

RECENT FINDINGS

While initially approached by means of open surgical hip dislocation, recent literature has shown generally good outcomes of arthroscopic treatment for femoroacetabular impingement. Modern advances in hip arthroscopy technique and implants now allow for labral repair or reconstruction when indicated. Arthroscopic treatment of femoroacetabular impingement results in significant improvements in patient pain and function, with low complication rates and high patient satisfaction. A majority of improvements in these patients occur within 1 to 2 years post-operatively. Hip arthroscopy for femoroacetabular impingement yields the best results in patients without significant arthritis or hip dysplasia.

The Natural History of Femoroacetabular Impingement

BACKGROUND

Structural hip abnormalities have long been suspected of causing hip osteoarthritis. The concept of deformity of the proximal femur as a cause of osteoarthritis (OA) started with description of the tilt deformity and progressed to the pistol grip, then eventually cam-type femoroacetabular impingement (FAI). Acetabular over-coverage or retroversion as a cause of impingement is commonly referred to as pincer-type FAI. The primary research question we asked was: what is the natural history of hips with FAI?

METHODS

We reviewed the literature to identify studies with cross-sectional and longitudinal evidence of the effect of FAI on the development of or association with hip OA.

RESULTS

In cross-sectional and longitudinal natural history studies of hip OA, cam-type FAI has consistently shown an association with developing OA. In regard to pincer-type FAI, the data are less convincing with some studies suggesting an increased risk and others showing a protective effect of the acetabular over-coverage. It is clear that not all patients with cam FAI get OA but the altered anatomy does increase the relative risk of developing OA.

CONCLUSIONS

Cam-type FAI is associated with the development of hip OA; however, there is no role for prophylactic surgery in the asymptomatic hip with the anatomy predisposing to FAI. Further interventional studies are needed to determine whether surgical correction of cam-type FAI in the symptomatic hip alters the natural history of the condition.

Increased pelvic mobility and altered hip muscles contraction patterns: two-year follow-up cam-FAIS corrective surgery

Femoroacetabular impingement syndrome (FAIS) surgery can produce improvements in function and patient satisfaction; however, data on muscle assessment and kinematics of high mobility tasks of post-operative patients is limited. The purpose of this study was to evaluate kinematics and muscle activity during a deep squat task, as well as muscle strength in a 2-year follow-up FAIS corrective surgery. Eleven cam morphology patients underwent motion and electromyography capture while performing a squat task prior and 2-years after osteochondroplasty and were BMI-, age- and sex-matched to 11 healthy control (CTRL) participants. Isometric muscle strength, flexibility and patient-reported outcome measures (PROMs) were also evaluated. Post-operative FAIS was significantly weaker during hip flexion (23%) and hip flexion-with-abduction (25%) movements when compared with CTRL, no improvements in squat depth were observed. However, post-operative FAIS increased the pelvic range of motion during the squat descent (P = 0.016) and ascent (P = 0.047). They had greater peak activity for the semitendinosus and total muscle activity for the gluteus medius, but decreased peak activity for the glutei and rectus femoris during squat descent; greater total muscle activity for the tensor fascia latae was observed during squat ascent (P = 0.005). Although not improving squat depth, post-operative patients increased pelvic ROM and showed positive PROMs. The muscle weakness associated with hip flexion and flexion-with-abduction observed at the follow-up can be associated with the alterations in the muscle activity and neuromuscular patterns. Rehabilitation programs should focus on increasing pelvis and hip muscles flexibility and strength.

The association between specific sports activities and sport performance following hip arthroscopy for femoroacetabular impingement syndrome: A secondary analysis of a cross-sectional cohort study including 184 athletes

The main purpose of this secondary analysis was to compare the proportion of athletes with moderate-to-extreme difficulties in eight specific sport activities in athletes with optimal versus impaired sport performance after a hip arthroscopy for femoroacetabular impingement syndrome. Subjects were identified in a nationwide registry and invited to answer a return to sport and performance questionnaire, and the Copenhagen Hip and Groin Outcome Score Sport subscale investigating difficulties in eight specific sports activities (HAGOS sport items) as; none, mild, moderate, severe or extreme. Subjects were divided into two groups based on sport performance (optimal or impaired). The proportion of athletes with none-to-mild versus moderate-to-extreme difficulties in the eight specific sport activities was compared between groups. The association between difficulties in sport activities and sport performance were investigated using logistic regression analysis. One hundred and eighty-four athletes (31 athletes with optimal and 153 athletes with impaired sport performance) were included at a mean follow-up of 33.1 ± 16.3 months. Up to six athletes (<20%) with optimal sport performance had moderate-to-extreme difficulties in sport activities. Contrary, 43–108 athletes (28.1–70.6%) with impaired performance had moderate-to-extreme difficulties in sport activities. Furthermore, moderate-to-extreme difficulties in HAGOS sport items: ‘running as fast as you can’ and ‘kicking, skating etc.’ increased the odds (14.7 and 6.1 times, respectively) of having impaired sport performance. Many athletes with impaired sport performance reported moderate-to-extreme difficulties in sport activities, specifically moderate-to-extreme difficulties in ‘running as fast as you can’ and ‘kicking, skating etc.’ were associated with patients having impaired sport performance.

Understanding Preoperative Demographics and Risk Factors for Early Revision Surgery in Patients Undergoing Hip Arthroscopic Surgery: A Large Database Study

BACKGROUND

Hip arthroscopic surgery has become an increasingly common surgical technique to diagnose and treat various hip abnormalities. While increased efficacy has been reported, debate remains regarding appropriate surgical indications. Multiple factors including patient demographics, surgical procedure, and underlying disease have been associated with poor surgical outcomes. Preoperative diagnostic and treatment interventions including physical therapy and injections may affect surgical indications and outcomes.

PURPOSE

To identify patient characteristics and preoperative factors associated with an increased risk of early revision surgery and/or extended postoperative medical care after index hip arthroscopic surgery.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Utah's All Payer Claims Database, a state-mandated registry containing data from all payers, including private insurance, Medicare Advantage, and Medicaid, was queried to identify patients who underwent hip arthroscopic surgery during a 3-year period (January 1, 2013, to December 31, 2015). Demographics, comorbidities, nonoperative care modalities, pain medications, and revision procedures were collected using claims data at 6 months preoperatively and 12 months postoperatively.

RESULTS

A total of 1283 patients who underwent primary hip arthroscopic surgery were analyzed, of whom 57.6% (n = 739) were female. Within 1 year of index surgery, 7.8% and 2.1% of patients underwent revision hip arthroscopic surgery and conversion to total hip arthroplasty (THA), respectively. Patients older than 60 years and male patients were more likely to undergo revision arthroscopic surgery (odds ratio [OR], 0.89; P < .001 and OR, 1.59; P = .04, respectively) and convert to THA (OR, 1.03; P = .01 and OR, 2.25; P = .05, respectively). Preoperative opioid use was significantly associated with increased odds of revision surgery (OR, 1.64; P = .05) and THA (OR, 2.70; P = .03). No significant relationship existed between preoperative physical therapy or intra-articular hip injections and revision hip arthroscopic surgery (OR, 1.20; P = .45 and OR, 1.18; P = .52, respectively) or conversion to THA (OR, 0.89; P = .79 and OR, 0.71; P = .46, respectively).

CONCLUSION

This study showed that predictable patient factors can effectively guide preoperative decision making and may improve prognosis. Certain patient pools require optimization preoperatively, and a subset of patients appears to require additional surgical indications.

The Pattern of Acetabular Cartilage Wear Is Hip Morphology-dependent and Patient Demographic-dependent

BACKGROUND

Acetabular cartilage damage has been described in patients with femoroacetabular impingement (FAI). However, most reports of articular cartilage damage in hip FAI have been focused on the acetabular cartilage and derived from single-center, retrospective studies of relatively small patient cohorts. Identifying patterns of articular cartilage wear is important in patient selection, treatment prognosis, and determining whether patterns of intraarticular cartilage wear are secondary to abnormal hip morphology. Using a multicenter, observational cohort, we sought to determine whether there was a specific pattern of cartilage wear across acetabular and femoral articular cartilage among patients with symptomatic FAI.

QUESTIONS/PURPOSES

(1) Is there is a specific pattern of cartilage wear in the acetabulum and femoral head, assessed during hip arthroscopy, in cam FAI, pincer, and mixed-type hip pathologies? (2) Are there specific patterns of cartilage wear associated with duration of symptoms, age, and/or body mass index (BMI)?

METHODS

A multicenter observational cohort and a hip preservation database from a senior author were used to identify 802 patients who underwent hip arthroscopy for the treatment of symptomatic FAI. The diagnosis of cam, pincer, or mixed-type FAI was determined by each treating surgeon at each institution using the minimum basic criteria of pain in the affected hip for a period of > 3 months, hip ROM, and radiographic findings. Acetabular and femoral head cartilage lesions were classified arthroscopically by location and severity for each group (cam, pincer, or mixed FAI). Cartilage wear was classified using the Beck classification and defined as cartilage lesions greater than Grade 1 (normal macroscopically sound cartilage). The assessment of cartilage wear was performed arthroscopically by experienced hip preservation surgeons who are a part of ANCHOR, a multicenter group that uses a longitudinally maintained database to investigate issues related to hip preservation surgery. Clinical characteristics, radiographic findings, and acetabular and femoral head damage by location and severity of wear were reported based on patient diagnoses of cam (n = 472), mixed (n = 290), and pincer (n = 40) FAI hip pathologies. Wald chi-square tests were used to test for differences in the presence of wear in each cartilage quadrant across hip pathologies, duration of symptoms, age, and BMI. One-way analysis of variance tests were used to test for differences in average grade of wear in each cartilage quadrant across hip pathologies, duration of symptoms, age, and BMI. A bivariate logistic regression model was used to identify factors independently associated with the presence of cartilage wear in the acetabulum and femoral head. Acetabular cartilage wear was present in 743 of 802 patients (93%) in the cohort. Femoral head cartilage wear was observed in only 130 (16%).

RESULTS

We found significant associations between acetabular patterns of wear and FAI hip pathologies; specifically, we observed more frequent and severe debonding of acetabular cartilage in patients with symptomatic cam (93%, 1.7 ± 1.1 grade) and mixed (97%, 1.7 ± 1.2 grade) FAI compared with Pincer (75%, 1.5 ± 0.9 grade) FAI hip pathologies (p < 0.001). Superolateral peripheral cartilage lesions occurred more frequently and with greater severity in patients with cam (90% [416 of 472] prevalence, 3.1 ± 1.1 grade) and mixed (91% [260 of 290] prevalence, 3.1 ± 1.1 grade) FAI than in pincer (60% [24 of 40] prevalence, 2.2 ± 1.1 grade) FAI hip pathologies (p < 0.0001). Conversely, patients with pincer FAI most commonly demonstrated cartilage lesions with an even distribution at the anterior and superolateral acetabular rim: 64% (25 of 40) (mean grade 2.1 ± 1.0) and 60% (24 of 40) mean grade 2.2 ± 1.1, respectively. Age was associated with increased presence of wear in both the acetabulum (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.2-1.7; p = 0.005) and femoral head (OR, 1.08; 95% CI, 1.6-1.1; p < 0.001). BMI was associated with a greater presence of wear only in the femoral head (OR, 1.1; 95% CI, 1.2-1.1; p = 0.002). Specifically, compared with patients with a BMI < 30 kg/m, patients with a BMI ≥ 30 kg/m presented with more frequent and more severe lesions in the posterior peripheral acetabular rim (42% [47 of 117] versus 26% [171 of 677], p = 0.0006; grade 1.9 ± 1.3 versus grade 1.4 ± 0.9, p < 0.001), the anterolateral femoral head (22% [20 of 117] versus 9% [60 of 67], p = 0.006), and the anteromedial femoral head (15% [16 of 117] versus 6% [39 of 677], p = 0.002; grade 1.3 ± 0.8 versus grade 1.1 ± 0.6, p = 0.04). In general, we found that older patients (≥ 50 years old) presented with more frequent and more severe lesions in both the acetabulum and femoral head. We found no association between hip pathology and cartilage wear patterns in the examined femoral heads.

CONCLUSIONS

Hip morphology affects the pattern of acetabular cartilage wear. More frequent and severe cartilage lesions were observed in patients with symptomatic FAI cam and mixed-type hip pathologies. Surgical attempts to restore normal anatomy to avoid FAI should be performed to potentially improve long-term joint homeostasis. Increasing age is an independent risk for cartilage wear in both the acetabulum and femoral head. Additionally, increased BMI is an independent risk factor for cartilage wear in the femoral head. In the future, prospective studies should provide further insight into the pathomechanics of early degenerative changes associated with hip FAI deformities.

LEVEL OF EVIDENCE

Level III, prognostic study.

Cam FAI and Smaller Neck Angles Increase Subchondral Bone Stresses During Squatting: A Finite Element Analysis

BACKGROUND

Individuals with a cam deformity and a decreased (varus) femoral neck-shaft angle may be predisposed to symptomatic femoroacetabular impingement (FAI). However, it is unclear what combined effects the cam deformity and neck angle have on acetabular cartilage and subchondral bone stresses during an impinging squat motion. We therefore used finite element analysis to examine the combined effects of cam morphology and femoral neck-shaft angle on acetabular cartilage and subchondral bone stresses during squatting, examining the differences in stress characteristics between symptomatic and asymptomatic individuals with cam deformities and individuals without cam deformities and no hip pain.

QUESTIONS/PURPOSES

Using finite element analysis in this population, we asked: (1) What are the differences in acetabular cartilage stresses? (2) What are the differences in subchondral bone stresses? (3) What are the effects of high and low femoral neck-shaft angles on these stresses?

METHODS

Six male participants were included to represent three groups (symptomatic cam, asymptomatic cam, control without cam deformity) with two participants per group, one with the highest femoral neck-shaft angle and one with the lowest (that is, most valgus and most varus neck angles, respectively). Each participant's finite element hip models were reconstructed from imaging data and assigned subject-specific bone material properties. Hip contact forces during squatting were determined and applied to the finite element models to examine maximum shear stresses in the acetabular cartilage and subchondral bone.

RESULTS

Both groups with cam deformities experienced higher subchondral bone stresses than cartilage stresses. Both groups with cam deformities also had higher subchondral bone stresses (symptomatic with high and low femoral neck-shaft angle = 14.1 and 15.8 MPa, respectively; asymptomatic with high and low femoral neck-shaft angle = 10.9 and 13.0 MPa, respectively) compared with the control subjects (high and low femoral neck-shaft angle = 6.4 and 6.5 MPa, respectively). The symptomatic and asymptomatic participants with low femoral neck-shaft angles had the highest cartilage and subchondral bone stresses in their respective subgroups. The asymptomatic participant with low femoral neck-shaft angle (123°) demonstrated anterolateral subchondral bone stresses (13.0 MPa), similar to the symptomatic group. The control group also showed no differences between cartilage and subchondral bone stresses.

CONCLUSIONS

The resultant subchondral bone stresses modeled here coincide with findings that acetabular subchondral bone is denser in hips with cam lesions. Future laboratory studies will expand the parametric finite element analyses, varying these anatomic and subchondral bone stiffness parameters to better understand the contributions to the pathomechanism of FAI.

CLINICAL RELEVANCE

Individuals with a cam deformity and more varus neck orientation may experience elevated subchondral bone stresses, which may increase the risks of early clinical signs and degenerative processes associated with FAI, whereas individuals with cam morphology and normal-to-higher femoral neck-shaft angles may be at lesser risk of disease progression that would potentially require surgical intervention.

Unravelling the hip pistol grip/cam deformity: Origins to joint degeneration

This article reviews a body of work performed by the investigators over 9 years that has addressed the significance of cam morphology in the development of hip osteoarthritis (OA). Early hip joint degeneration is a common clinical presentation and preexisting abnormal joint morphology is a risk factor for its development. Interrogating Hill's criteria, we tested whether cam-type femoroacetabular impingement leads to hip OA. Strength of association was identified between cam morphology, reduced range-of-movement, hip pain, and cartilage degeneration. By studying a pediatric population, we were able to characterize the temporality between cam morphology (occurring 1st) and joint degeneration. Using in silico (finite element) and in vivo (imaging biomarkers) studies, we demonstrated the biological plausibility of how a cam deformity can lead to joint degeneration. Furthermore, we were able to show a biological gradient between degree of cam deformity and extent of articular damage. However, not all patients develop joint degeneration and we were able to characterize which factors contribute to this (specificity). Lastly, we were able to show that by removing the cam morphology, one could positively influence the degenerative process (experiment). The findings of this body of work show consistency and coherence with the literature. Furthermore, they illustrate how cam morphology can lead to early joint degeneration analogous to SCFE, dysplasia, and joint mal-reduction post-injury. The findings of this study open new avenues on the association between cam morphology and OA including recommendations for the study, screening, follow-up, and assessment (patient-specific) of individuals with cam morphology in order to prevent early joint degeneration. Statement of significance: By satisfying Hill's criteria, one can deduct that in some individuals, cam morphology is a cause of OA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3125-3135, 2018.

Bone density changes following surgical correction of femoroacetabular impingement deformities

OBJECTIVE

Femoroacetabular impingement (FAI) involves abnormal hip biomechanics due to deformities and is associated with osteoarthritis. Bone mineral density (BMD) in the acetabulum is higher in subjects with convex femoral (cam) FAI deformities compared to control subjects. The objective of this study was to assess post-operative changes of BMD with and without surgical correction of the cam deformity.

DESIGN

Thirteen patients with bilateral cam deformities but unilateral symptoms underwent pre-operative and follow-up computed tomography (CT) scans of both hips. The deformity was surgically removed from the symptomatic hip. BMD was measured in regions of interest (ROI) around the superior acetabulum from CT scans at both time points. The contralateral untreated hip was used as a within-patient control. Changes in BMD were assessed by two-way repeated measures ANOVA (side, time) and paired t-tests.

RESULTS

A greater BMD decrease was seen in the treated compared to the untreated hip (P < 0.0018). BMD within the superior acetabulum decreased by 39 mg/cc on the treated side (P < 0.0001) but only 9 mg/cc (P = 0.15) in the untreated contralateral hip. These changes represent 7.1% and 1.7% of the pre-operative BMD on the respective sides.

CONCLUSIONS

BMD decreased in the treated hip, suggesting a positive effect of surgical correction in relieving stresses within the hip joint. Longer term follow-up is required to assess the ultimate fate of the articular cartilage within the joint. This study showed that surgical correction of the cam deformity in patients with FAI may alter the pathological biomechanics within the joint.

Correlation of Patient Symptoms With Labral and Articular Cartilage Damage in Femoroacetabular Impingement

Background:

Femoroacetabular impingement (FAI) can lead to labral and articular cartilage injuries as well as early osteoarthritis of the hip. Currently, the association of patient symptoms with the progression of labral and articular cartilage injuries due to FAI is poorly understood.

Purpose:

To evaluate the correlation between patient-reported outcome (PRO) scores and cartilage compositional changes seen on quantitative magnetic resonance imaging (MRI) as well as cartilage and labral damage seen during arthroscopic surgery in patients with FAI.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Patients were prospectively enrolled before hip arthroscopic surgery for symptomatic FAI. Patients were included if they had cam-type FAI without radiographic arthritis. All patients completed PRO scores, including the Hip disability and Osteoarthritis Outcome Score (HOOS) and a visual analog scale for pain. MRI with mapping sequences (T_1ρ and T₂) on both the acetabular and femoral regions was performed before surgery to quantitatively assess the cartilage composition. During arthroscopic surgery, cartilage and labral injury grades were recorded using the Beck classification. Pearson and Spearman correlation coefficients were then obtained to evaluate the association between chondrolabral changes and PRO scores.

Results:

A total of 46 patients (46 hips) were included for analysis (mean age, 35.5 years; mean body mass index [BMI], 23.9 kg/m²; 59% male). Increasing BMI was correlated with a more severe acetabular cartilage grade (ρ = 0.37; 95% CI, 0.08-0.65). A greater alpha angle was correlated with an increased labral tear grade (ρ = 0.59; 95% CI, 0.37-0.82) and acetabular cartilage injuries (ρ = 0.61; 95% CI, 0.42-0.80). With respect to PRO scores, increasing femoral cartilage damage in the anterosuperior femoral head region, as measured on quantitative MRI using T_1ρ and T₂ mapping, correlated with lower (worse) scores on the HOOS Activities of Daily Living (r = 0.35; 95% CI, 0.06-0.64), Symptoms (r = 0.32; 95% CI, 0.06-0.57), and Pain (r = 0.31; 95% CI, 0.06-0.55) subscales. There was no correlation between PRO scores and acetabular cartilage damage or labral tearing found on quantitative MRI or during arthroscopic surgery.

Conclusion:

Femoral cartilage damage, as measured on T_1ρ and T₂ mapping, appears to have a greater correlation with clinical symptoms than acetabular cartilage damage or labral tears in patients with symptomatic FAI.