CHAPTER SYNOPSIS
Hip arthroscopy is an emerging field in the treatment of hip disease. Because of anatomic restraints, it presents unique surgical challenges. However, given proper indications and patient selection, it can be safely and effectively used to treat a variety of intraarticular and extraarticular diagnoses. This field is rapidly developing as an important tool and should be familiar to any surgeon treating hip pathology.
IMPORTANT POINTS:
- 1
Common indications include labral tears, impingement, loose bodies, and chondral damage.
- 2
Contraindications include an excessively large patient, protrusio, ankylosis, and poor bone stock.
- 3
Procedures may be performed with the patient in the lateral or supine position.
- 4
Proper portal position (anterior, anterolateral, posterolateral, distal) and adequate distraction are crucial.
CLINICAL/SURGICAL PEARLS:
- 1
Entry into the joint may be facilitated with properly aligned distraction forces and slight hip abduction.
- 2
Mobility in this restricted joint is improved by arthroscopically incising the capsule where portals penetrate.
- 3
Hip rotation and use of both 30-degree and 70-degree arthroscopes allow visualization of almost all the joint.
INTRODUCTION
Arthroscopy of the hip, proposed by Burman in 1931 in a cadaveric study, was first used clinically in 1939 by Takagi. Initially a diagnostic procedure only, since the 1980s it has been further developed for therapeutic interventions by surgeons such as Byrd, McCarthy and Lee, Philippon, and Sampson et al. More indications and interventions have been revealed through improved instrumentation, minimally invasive techniques, and increased understanding of hip pathology. Many patients previously believed to be inappropriate for more aggressive surgical interventions are treatable with arthroscopic procedures.
Indications
Current indications for hip arthroscopy fall into two categories, diagnostic and therapeutic, though there is considerable overlap between the two. The undiagnosed painful hip often can be elucidated with arthroscopic examination. Arthroscopy allows inspection and biopsy of synovium in suspected inflammatory or infectious arthropathy. Accurate identification of chondral injury and articular delamination is challenging with current imaging modalities and in some instances may be better documented by arthroscopic examination. In a similar manner, the degree of osteonecrosis or progression of osteoarthritis may be evaluated. Combined with fluoroscopy, areas of impingement in femoroacetabular impingement can be identified. Arthroscopy also has been used to ascertain the source of pain in patients who have undergone arthroplasty, such as psoas irritation or bearing impingement.
Hip arthroscopy has been used for many therapeutic interventions, including synovectomy or septic drainage. Loose bodies such as those associated with synovial chondromatosis may be removed, as may foreign bodies. Chondral injury is treated with chondroplasty and/or microfracture techniques familiar to the knee. Arthritic osteophytes may be removed arthroscopically. Adhesive capsulitis can be treated with capsular resection. Many indications exist for traumatic injuries as well. Hip arthroscopy has been used to assess the accuracy of reduction in acetabular fracture and to assist with the reduction and fixation of femoral head fractures or the removal of small intraarticular fragments. Painful ligamentum teres tears may be debrided, as can trochanteric bursitis. Iliopsoas tendonitis and accompanying band pain can be treated with arthroscopic release. Femoroacetabular impingement often leads to labral and chondral pathology. Hip arthroscopy can be used to debride or repair a torn labrum and resect the areas of bony impingement.
Contraindications
Because the hip is the deepest joint in the body, access may be limited in even moderately overweight patients. Instruments often are inadequate in length and soft tissue impediments too great to permit hip arthroscopy in obese patients. Inadequate joint distraction or protrusio may preclude performing intraarticular work. Arthroscopy should not be performed on patients with significant systemic illness or through areas of infection. Ankylosis, severe heterotopic ossification, and severely restricted motion of the hip are contraindications to arthroscopy. Because of the requirement for mechanical distraction, poor bone quality risks femoral neck fracture. Arthroscopic debridement has not been effective in severe osteoarthritis.
INDICATIONS
Synovial biopsy or synovectomy
Chondral lesions (chondroplasty or microfracture)
Femoroacetabular impingement
Loose body or foreign body removal
Adhesive capsulitis
Assistance with fracture reduction
Assessment of osteonecrosis
Psoas or rectus tendonitis or bursitis
Postarthroplasty evaluation
Drainage of sepsis
Osteophyte removal
Ligamentum teres debridement
Labral tear debridement or repair
Undiagnosed or unresolved hip pain
CONTRAINDICATIONS
Obese patient
Inability to obtain adequate distraction
Superficial infection or systemic illness
Protrusio acetabuli
Ankylosis
Poor bone quality
Diagnostic Workup
Patient selection is paramount in hip arthroscopy. Many patients have nonspecific radiographic findings yet have considerable symptoms, limitations, and physical signs of pathology. Patients often are younger than the typical patient with degenerative changes. When taking a thorough history of this subset of patients, remember that extraarticular causes of pain are more common than intraarticular causes. Groin pain or pain in the region of the anteromedial thigh is more specific for hip pathology but also can be seen in upper lumbar radiculopathies. Lateral pain and tenderness can be associated with trochanteric bursitis, external snapping hip, or abductor enthesopathy. Posterior pain often may be attributed to sacroiliac or lumbar sources but less frequently can be associated with hip disorders. Patients may relate a traumatic or twisting mechanism with sudden onset of symptoms. Intraarticular symptoms usually are reproducible and activity related.
Physical examination should include careful evaluation of the lumbar, pelvic, and hip regions. Gait and stance should be evaluated first. A Trendelenburg gait exists because of an attempt to minimize the joint reactive forces because of pain, abductor weakness, or both. A positive Trendelenburg test indicates abductor weakness in single-leg stance. In double-leg stance the examiner should check for pelvic obliquity and determine whether it is fixed (more often related to spinal pathology) or correctable (could be either spine or hip related). Leg-length discrepancy may contribute to low back pain and buttock pain. The lumber spine should be evaluated for curvature, spasm, limited or painful range of motion, or tenderness.
Examination of the hip should start with inspection, looking for gluteal atrophy. The hip should be palpated for any regions of tenderness. Next, an assessment of range of motion should be made. Osteoarthritic patients may lose motion, especially internal rotation, whereas loss of internal rotation in a young patient may indicate slipped capital femoral epiphysis. Osteoarthritis also demonstrates pain with gentle rolling of the leg while supine and may have crepitation with movement. A straight-leg raise is more likely to be associated with hip pathology when positive with active motion; a positive test result with passive motion may be radicular in nature. Coxa sultans shows snapping of the psoas or rectus over the hip capsule with active extension and external rotation. The FABER ( f lexion, ab duction, e xternal r otation) or Patrick’s test may elicit a painful sacroiliac joint posteriorly and/or press the femoral head against a damaged anterior labrum. Pain with hip flexion to 90 degrees or more with slight adduction and internal rotation can assess anterior impingement ( Fig. 4-1 ); posterior impingement is evaluated with the affected hip in extension over the edge of the table and externally rotated while the opposite hip is flexed. If the cause of the patient’s pain is unclear, an intraarticular bupivacaine injection can help differentiate intraarticular and extraarticular pathology.
Imaging
Plain radiographs are an important part of the evaluation of any painful hip, but they are unreliable for many intraarticular diagnoses. Standard radiographs should include at a minimum an anteroposterior pelvis and lateral radiographs. If appropriate, a false profile view can evaluate for anterior hip dysplasia. Evidence of impingement often is seen on plain films. The crossover sign indicates relative acetabular retroversion when the outlines of the posterior and anterior walls on the anteroposterior view cross more distally rather than converge at the superolateral margin ( Fig. 4-2 ). The observer must verify that the anteroposterior view is not rotated or flexed or extended (an inlet or outlet view). In the properly rotated anteroposterior pelvis radiograph the tip of the sacrum should be approximately 6 cm from the top of the pubic symphysis. Bony impingement has been classified ( Fig. 4-3 ) as “cam type” when the primary deformity is on the femur ( Fig. 4-4 ) or “pincer type” when the primary deformity is in the acetabulum ( Fig. 4-5 ). Many times, however, elements of both types of deformity exist simultaneously. Convexity of the superior junction of the femoral head and neck is seen with cam-type impingement, and anterolateral osteophytic overhang is seen in pincer-type impingement. Impingement may contribute to both labral abutment and chondrolabral damage as well as sliding subluxation, leading to medial and posterior wear patterns. Synovial chondromatosis and loose bodies often are readily visualized on plain films.
Nuclear imaging is seldom used in the evaluation of hip pain, but it can rule out a stress fracture of the femoral neck. Computed tomographic scans are helpful to identify loose bodies within the joint, and a computed tomographic arthrogram may be useful in the situation where a patient cannot undergo magnetic resonance imaging (MRI).
MRI is the modality of choice for suspected labral tears, stress fractures of the femoral neck, and osteonecrosis. Chondral injury is less reliably identified. The accuracy of MRI for labral imaging is markedly improved by intraarticular administration of gadolinium contrast. Ask the radiologist to aspirate before the addition of contrast and to send the fluid for cell count and culture, which can rule out inflammatory arthritis and infection.
Surgical Technique
Several anatomic considerations must be taken into account when undertaking hip arthroscopy. Access can be difficult because the hip is the deepest and most constrained joint in the body. It is covered by a thick, capsular envelope of tissue. This requires accurate positioning, placement of portals, and proper instrumentation. The space between the femoral head and acetabulum is naturally quite limited and must be distracted to gain enough working space. The various neurovascular structures in the region must be considered with any portal and its trajectory.
Positioning
The patient may undergo general or spinal anesthesia, but either technique requires adequate muscle relaxation to allow distraction. The patient may be positioned either supine or lateral. Advocates of the lateral position claim easier maneuvering of instruments because adipose tissue falls away from the field and facilitates entrance into the hip joint. This requires special traction equipment and a thigh post but is otherwise performed on a standard operating table. The supine position is easy to set up and uses a fracture table ( Fig. 4-6 ). Care must be taken in either case to place the thigh post against the medial thigh rather than the perineum. This avoids potential pudendal or perineal nerve injury and provides the appropriate line of force. The goal is to combine distraction through traction and lateral force through the post to produce a resultant vector in line with the femoral neck. Slight hip flexion and neutral to slight external rotation relax the capsule and facilitate distraction. Approximately 25 to 50 lb of traction should be sufficient to produce 8 to 10 mm of distraction. Once a portal is established, the capsular vacuum is released. This, combined with creep of the soft tissues after several minutes, decreases the need for distraction, and it should be lessened after a period. Although specific study data are lacking, traction times of greater than 90 minutes should be avoided. C-arm fluoroscopy should be used before prepping and draping to ensure appropriate positioning and access for intraoperative imaging.
