Femoroacetabular Impingement

Introduction

Femoroacetabular impingement (FAI) syndrome is a motion-related clinical disorder of the hip involving premature contact between the acetabulum and the proximal femur, resulting in specific symptomatic clinical signs and radiographic findings. [1][2] Degenerative changes and osteoarthritis may occur Because of this abnormal contact, it exists for a long time. [3]

Hip Joint

Clinically Relevant Anatomy

The hip joint (acetabular femoral joint) is the synovial joint formed between the femur and the acetabulum of the pelvis. The femoral head is covered with type II collagen (hyaline cartilage) and proteoglycans. The acetabulum is the sunken part of the ball and socket joint. acetabular ring Fibrocartilage called the labrum deepens the acetabulum and improves stability of the hip joint. A detailed review of hip anatomy is provided here.

Injury Mechanism/Pathological Process FAI syndrome is associated with three changes in hip morphology: cam clamp and combination cam and clamp. These forms are considered fairly common (approximately 30% of the population) [4], including Hip symptoms. Raveendran et al. [5] found that 25% of males and 10% of females had evidence of cam morphology on at least one buttock, whereas 6-7% of males and 10% of females showed pincer morphology. Therefore, the presence of a cam or pincer morphology alone is insufficient for the diagnosis of FAI syndrome. [2] Cam morphology describes the flattening or convexity of the femoral head-neck junction. [2] This morphology is more common in younger athletes. [3][5][6] Pincer morphology describes over-coverage of the femoral head by the acetabulum, where the acetabular rim extends beyond the Typical amount for a focal area or more generally for the entire acetabular rim. [2] This morphology is more common in females. [3][5][7] People with a cam and pincer combination often suffer from a slipped epiphysis of the femur known as S C F E . They exhibit varying degrees of hip hit. An estimated 85% of patients with FAI have this type of mixed morphology [3] although Raveendran et al. [5] found only 2% of subjects in their prospective longitudinal cohort year population). [5] Cam and pincer morphologies can cause Symptoms of FAI syndrome result from damage to the articular cartilage and labrum due to impingement between the acetabular rim and femoral head during movement. [8] Metabolic analysis of tissue samples by Chinzei et al. [8] suggested that articular cartilage may be the major site Hip inflammation and degeneration in FAI, and if OA progresses, metabolic activity spreads to the labrum, synovium, and labrum. Given that both types of morphology may be present in asymptomatic individuals, Casartelli et al. [9] suggested that other factors related to skeletal structure may Associated with FAI syndrome, including: Weakness of the deep muscles of the hip, which affects the stability of the hip and causes secondary dynamic overload in the hip. The femoral head slides anteriorly into the acetabulum and increases joint loading. [9] Repeated loading of the labrum leads to Nociceptors in this structure are upregulated through the production of neurotransmitters such as substance P. [9] Etiology According to a systematic review by Chaudhry and Ayeni [3], the etiology of FAI syndrome may be multifactorial. Further research is needed to better The development of FAI-associated morphologies is unknown, but the following factors may be involved in their development:[3] Intrinsic factors supporting: Radiological findings of FAI-associated morphologies in subjects with affected siblings The female pincer morphology is exposed to repetitive and often supraphysiological hip rotation and hip flexion during development in childhood and adolescence (e.g., hockey basketball or soccer). Repeated stress of this type may trigger adaptive remodeling that eventually develops into Symptoms and symptoms associated with FAI History of hip disease in children such as slipped epiphysis (SCFE) or Legge-Calve-Perthes disease may alter the shape of the femoral head Malunion following a femoral neck fracture may alter the contour of the femur Surgical overcorrection of conditions such as head/neck hip dysplasia may result in pincer morphology

Clinical Presentation

The heterogeneity of diagnostic criteria in past studies means that it is difficult to determine the full extent of physical impairment caused by FAI. [10] However, pain in FAI is generally considered to be worse with accelerated movement as well as with squatting, stair climbing, and prolonged exercise. SIT [11] For FAI who may have developed hip osteoarthritis, signs and symptoms more typical of this condition can be identified.

In the Warwick protocol on FAI syndrome published in 2016, the authors noted that a specific triad of clinical and imaging findings is required for the diagnosis of FAI. [2]

Symptoms

The main symptoms reported for this condition are:

• Moderate to pronounced hip or groin pain associated with certain movements or postures [2]
• Report pain in the back of the thigh or buttocks[2][12]
• Stiffness
• Restricted hip range of motion
• Clicking and/or catching
• Locking or giving way [2][12]
• Decreased ability to perform activities of daily living and motor activities. [13]

Clinical Findings

According to the 2016 Warwick protocol, there is no single clinical sign that would indicate a diagnosis of FAI. [2] Issues with low specificity of tests such as the impact test (FADIR) limit their accuracy and use as stand-alone tests. [14] results in false positives and inaccurate diagnoses FAI syndrome and incorrect treatment may occur. [14] Smithson [14] suggested that a set of tests could be studied to develop clinical prediction rules to achieve high specificity and sensitivity for more accurate diagnosis in the clinical setting.

• Various pain-inducing hip impingement tests are used clinically. The most commonly used test is flexion adduction internal rotation (FADIR), but it is not specific. [2][15] The provocative FADIR location is associated with impingement of the anterior acetabular rim. [12] Pain related Passively moving the hip from flexion to extension while maintaining the hip abducted and externally rotated position while the leg is suspended from the examination table activates the posterior edge. [12]

[16]

• The range of motion of the hip is often limited, most commonly by internal rotation when the hip is flexed. [2] However, Diamond et al. [10] noted that in some studies, asymptomatic FAI was not controlled for imaging. Caution is therefore needed when generalizing these results, and further research will help clarify Effect of FAI on hip range of motion. [10]
• Single-limb squats can help identify hip abductor weakness. [12]
• Reproducibility of pain during hip flexion may indicate FAI or other intra-articular pathology. [12]
• Assess ascending and descending stairs, as this requires greater hip flexion than walking on a flat surface. [12]
• Findings of strength deficits associated with FAI (particularly hip flexion and adduction) have been reported in the literature, but as with studies investigating range of motion and FAI, some controls have not been imaged for asymptomatic FAI, so in generalizing these Caution is required with the results. [10] Further research will help clarify the effect of FAI on strength, especially functional rather than maximal muscle contraction. [10]

You can find an overview of the clinical assessment of femoroacetabular impingement here.

Imaging Findings

• For suspected FAI syndrome, anteroposterior pelvic x-ray and lateral femoral neck x-ray are initially recommended. These views can provide general information related to the hip as well as specific information related to cam or pincer morphology or other potential sources for the patient pain. [2]
  • Dunn’s lateral view shows that the deformity is anterolateral
  • The position of the frog legs shows a deformity on the anterior side. [17]

Alpha angle is a radiometric measurement used to assess cam morphology. The horizontal line for this angle is drawn from the center of the femoral head to the bottom of the femoral neck and the vertical line is drawn along the edge of the socket matching the center of the femur Femur [17] recently proposed a value of ≥60° as the definition of cam morphology. [18]

The Lateral Center Edge Angle (LCEA) measures the bony coverage of the femoral head by the acetabulum. Begin by drawing the best-fit circles for the inferior and medial borders of the femoral head. Next measure the angle between two lines drawn from the center of the circle: a line perpendicular to the center of the circle The longitudinal axis of the pelvis and another line extending to the lateral acetabular rim. [17] An LCEA greater than 39 degrees defines pincer impingement, while an LCEA less than 20 degrees indicates acetabular dysplasia. [19]

• Cross-sectional imaging (CT or MR arthrography) is recommended if further evaluation is required (eg, to better understand the 3D morphology of the hip joint or associated cartilage and labral lesions). [2]
• MR arthrography is generally preferred over MRI because it demonstrates greater accuracy in identifying labrum and cartilage defects. [20] However, recent studies have shown that 3T MRI is at least equivalent to 1.5T MRA for detecting these types of defects. [20]

From Chopra et al: [20] A complete tear of the anterior superior acetabular labrum with adjacent full-thickness cartilage defect was confirmed intraoperatively in a 26-year-old patient. Sagittal (a) T1 FS 1.5T MRA showing complete basal labral tear (arrow) and normal articular cartilage and (b) PD FS 3T MR image showing intact Basal lip tear (arrowhead) and full-thickness cartilage defect (arrowhead)

The role of advanced imaging in the diagnosis of FAI syndrome is controversial:

• Reiman et al [21] reported that in the studies included in their systematic review, patients had such a high pretest probability of FAI that advanced imaging did little to improve the probability of this diagnosis.
• Cunningham et al [22] found that advanced imaging (MRA or MRI) was never a cost-effective adjunct to a comprehensive history and physical examination for the diagnosis of FAI.
• Complementing the history and physical examination with diagnostic injections may be of value to general practitioners, but the benefit to specialists in a patient population with a higher prevalence of FAI and more sensitive physical examination skills is unclear. [twenty one]
• Kaya [23] proposed and tested a method for assessing contact pressure within the hip joint during cam-shaped flexion. Because this measurement was done using a fiber optic transducer during arthroscopic surgery, the diagnosis of FAI had been made before then. but it is recommended This intra-articular measurement will help:[23]

1. Provides a more detailed assessment of CAM morphology and associated pathophysiology
2. Establish intraoperative guidelines for the appropriate area and depth of orthopedic revision.

A video of this arthroscopic procedure can be viewed near the end of Kaya’s [23] open access article.

Differential Diagnosis

Red flag conditions for acute hip pain include:

• Tumour
• Infection
• Septic arthritis
• Osteomyelitis
• Fracture
• Avascular necrosis[24]

In athletes, other causes of hip pain include groin pathology, adductor muscle pathology, and exercise-induced pubic pain. [12]

Outcome Measures

• International Hip Outcomes Tool (iHOT)
• Hip and Groin Outcome Score (HAGOS)
• Hip Outcome Score (HOS)
• Harris Hip Score (HHS)[25]
• Non-arthritic Hip Score[25]

Management / Interventions

There is currently no high-level evidence to support the choice of definitive treatment for FAI syndrome. [2]

Researchers are still working to determine the best way to control this condition:

• Hip arthroscopy has been a common procedure but has shown only short-term benefits. [5][15][26][27]
• Peters et al. [28] found heterogeneity in the surgical criteria reported in the literature, questioning whether all studies were actually treating the same conditions. Only 56% of the reviewed studies included at least one surgical criterion from each of the three categories of recommendations Warwick Agreement[28]
  • The vast majority of studies (92%) in this scoping review used diagnostic imaging as standard, but there is no consensus on specific imaging modalities or cutoffs to determine when surgery is required. [28]
  • Failure of conservative treatment was found to be an uncommon surgical criterion in this review. [28]
• Multiple authors raised the issue of heterogeneity in diagnostic and surgical criteria across studies. [10][15][21]
• Reiman and Thorburg [15] compared the increase in shoulder arthroscopy between 2000 and 2010 with the rapid increase in surgical correction of FAI, which was not based on quality evidence.

Surgical Management

Arthroscopy is the most common FAI surgical procedure discussed in the literature and typically involves:

• Acetabuloplasty (trimming and reshaping of the acetabular rim)
• Labral repair/debridement
• and/or femoral osteoplasty (reshaping the head-neck junction of the femur). [27]

[29]

• A systematic review by Diamond et al. [10] found that hip arthroscopy for FAI appeared to improve range of motion in the sagittal but not frontal plane during gait. In addition, limitations in hip range of motion when climbing stairs did not improve after surgical correction The morphological findings led the authors to suggest that hip function in the sagittal and transverse planes may not resolve spontaneously after surgery and that patients may require postoperative training to regain normal range of motion. [10]
• In a systematic review published in 2017, a complication rate of 3.3% was calculated for hip arthroscopy reported in the UK literature. [30] Potential complications of surgical treatment include:
  • Neuropraxia[30]
  • Chrondral injury[30]
  • Labral injury[30]
  • Heterotopic ossification[30]
  • Compression injury, eg, pudendal nerve, labia majora of the scrotum [30]
  • Injury to the femoral head[30]
  • Adhesion[15][30]
  • Infection[30]
  • DVT[15][30]
  • CRPS[15][30]
  • Perineal skin damage[30]
  • Vascular injury (haematoma)[30]
  • Muscle pain[30]
  • Incomplete reshaping[30]
  • Femoral neck fracture[30]
  • Hip instability[30]
  • Iliopsoas tendinitis[30]
  • Avascular necrosis of femoral head[30]
  • Ankle pain[30]
  • Bursitis[30]

Sample hip internal rotation exercise from patient handout by Bennell et al (2014)

Surgical complications are a recommended area for future research to help inform the clinical decision-making process. [15]

Surgery and Post-Post Physiotherapy Program

A physiotherapist-prescribed rehabilitation program after arthroscopy improved the primary outcome (the International Hip Outcomes Tool and the exercise subscale of the Hip Outcomes Scale) at 14 weeks post-arthroscopy compared with a control group following arthroscopy to clinical relevance Undergo a self-management program under general guidance from your surgeon. [26] In the same study, the results at 24 weeks were inconclusive due to the small sample size. [26] This study did not assess physical outcomes.

• Subjects in the physical therapy group participated in 1 preoperative and 6 postoperative 30-minute physical therapy sessions. [26]
• Postoperative visits were on average two weeks apart, ending at 12 weeks.
• Treatment during these sessions includes educational manual therapy (forced release of key trigger points with optional lumbar spine mobility) and functional and movement specific training beginning 6-8 weeks post-op. [26]
• Begin training 10-12 weeks after surgery in the patient’s normal exercise environment. [26]
• In addition, these patients performed a daily home exercise program (see exercise chart below) and an unsupervised gym and aquatic exercise program (pool walk stationary bike cross trainer, eventual swimming and lower body resistance) at least twice a week. [26]

The full treatment plan can be viewed here. The home exercise form provided to patients in the physical therapy group can be viewed here in PDF format. The Return to Sport Guidelines for treating physical therapists can be viewed here in PDF format.

Conservative Management

• Casartelli et al. [9] suggested that improving neuromuscular function of the hip should be the goal of a conservative treatment regimen for FAI syndrome, given the weakness of the deep hip musculature and the expected subsequent reduction in hip dynamic stability. [9] Author recommendation: [9]
  • Hip-specific and functional lower extremity strengthening: deep hip external rotator abductors and flexors in the transverse frontal and sagittal planes to improve dynamic stability [9]
  • Core stability
  • Postural balance exercises[9][31]
• A randomized controlled trial by Mansell et al. [32] compared patient outcomes of surgical intervention with physical therapy. The results of the surgical and non-operative groups were not statistically significantly different, and on average, subjects in both groups reported no During the two-year follow-up, their condition improved. Outcomes are the Hip Outcomes Score (includes Activities of Daily Life and Exercise scales) International Hip Outcomes Facility Global Change Rating and Return to Work. Surgery including possible labia repair or Acetabular rim debridement and/or femoral osteoplasty as determined by the surgeon. The physical therapy program was tailored to each subject based on a standardized assessment conducted by a physical therapist. The program may include manual therapeutic motor control exercises and Mobility/stretching exercises are as follows:[27]

Manual TherapyMotor Control ExercisesMobility ExercisesHip Extension in Standing Movements (MWM)Forward Racquet Reverse LungeKneeling Internal RotationSelf-MobilizationHip Separation During Internal Rotation MWMIUnilateral Romanian Deadlift DowelHalf-Kneel FABER Self-Mobilization Loading Lateral Hip Partial Concentration MWM Heel Hover Lateral Pressdown Quadruped Rock Self-Mobilization and Lateral Distraction Loading Internal Rotation Side Plank Prone Figure-4 Self-Mobilization External Rotation Lateral Sliding Seated Isometric Hip Flexion ITB Soft Tissue Self-Mobilization on Foam Rolling Long Axis Hip Traction Supine Hip Flexion with Theraband Quadriceps Soft Tissue Self-Mobilization on Foam Rolling xx Piriformis/Glut Min Self-Myofascial Release Ball xx Standing 4 Stretches xx Kneeling three-plane mobilization

The procedure described above has been described in detail in the authors’ supplementary file, which can be viewed here.

Personalized Hip Treatment – UK Fashion Trial

Wall et al. [4] developed a conservative treatment plan based on a systematic review of the literature and the Delphi research group. A personalized hip treatment plan is designed to last 12 weeks with a minimum of 3 face-to-face and 3 phone/email contacts with a therapist physical therapist. For the purposes of the FASHION trial, a maximum of 10 physical therapist contacts are permitted. A comparative study between hip arthroscopy and individualized hip treatment plans showed that:

• Both hip arthroscopy and individualized hip therapy improve hip-related quality of life in patients with femoroacetabular impingement syndrome.
• Hip arthroscopy resulted in greater improvement than individualized hip therapy, a difference that was clinically meaningful.
• Further follow-up will reveal whether the clinical benefits of hip arthroscopy are maintained and whether it is cost-effective in the long run.

A complete personalized hip treatment plan is as follows:[4]

Core Component Description 1 Patient education and advice relative rest and lifestyle/ADL/exercise adjustments to minimize FAI eg avoiding deep hip flexion adduction and internal rotation 2 Patient assessment Comprehensive patient history Painless PROM for hip impingement testing and strength Flexion Stretch Abduction Adduction Internal Rotation and External Rotation 3 Help relieve pain Anti-inflammatory drugs or simple pain relievers for 2-4 weeks if anti-inflammatory drugs do not help start Control work (pelvic hip gluteal abs) progresses to non-violent stretching (hip external rotation hip flexion and extension abduction) and strengthening (glut max short external rotators glut med abdominals lower extremity general)

Optional components [4] describing manual therapeutic hip mobilization (e.g. traction AP glide) and trigger point working hip injections are indicated for patients who do not improve using the core therapeutic components described above. For the purpose of the FASHION trial, up to one steroid injection Include orthotics Custom orthotics as an alternative to physical therapists for treating biomechanical abnormalities Taping to assist in postural modifications such as strapping the thighs into external rotation and abduction Group-based therapy For the purposes of the fashion trial, group therapy can be Include but only in addition to the treatment of other pathologies/symptoms in addition to the core components Pathologies/symptoms thought to affect FAI may also be treated based on the findings of the treating physical therapist

For the purposes of the FASHIoN trial, hydroacupuncture, electrotherapy and strong manual techniques were excluded from the protocol. [4]

Bracing

Newcomb et al. [11] studied the immediate and long-term effects of wearing a brace. The brace is the Don Joy S.E.R.F./External Rotation Femoral Stability Model. [11] They found that:[11]

• Braces do alter the kinematics of patients with FAI by limiting the motion associated with hip impingement (flexion, internal rotation, and adduction of the hip) during common activities (squatting and descending stairs).
• The brace did not alter the kinematics of the single-limb squat.
• The kinematic changes identified did not reduce pain or improve patient-reported outcomes immediately or after 4 weeks of daily use of the brace.

The authors concluded that there may be a subset of patients with FAI syndrome who could benefit from a brace, but based on their specific study, do not support the use of a brace as a general conservative treatment for this condition. [11]

Prognosis

Patients treated for symptomatic FAI syndrome often report improvement in symptoms and are able to resume daily activities. [2] However, long-term prognosis is unclear, and it is unclear whether treatment of FAI syndrome prevents the development of hip osteoarthritis. [2] According to the author In the Warwick protocol, symptoms of FAI syndrome may worsen if treatment is not provided. [2]

Resources

• 2016 FAI Syndrome Warwick Agreement

Reprinted with permission from BMJ Journals via RightsLink Copyright Clearance

Presentations

Femoroacetabular Impingement by Adam Smithson, University of Nottingham This presentation, created by Adam Smithson as part of his MSc at the University of Nottingham, discusses the FAI and the accuracy of commonly used impingement tests. [14] View presentation