Hip Arthroscopy

The first investigations into hip arthroscopy date back to the 1930s.[1, 2] However, it was not until the 1980s that this procedure began its ascent as a mainstream hip treatment.[3] The indications for hip arthroscopy have become considerably broader since then, expanding to include not only intra-articular conditions but also various extra-articular processes and peripheral hip issues.[4, 5] Outcomes may vary substantially, depending on the specific pathologic condition that the procedure is being performed to address.

One of the most common indications for hip arthroscopy is management of femoroacetabular impingement (FAI) and associated labral tears.[6] Loose bodies, chondral pathology, degenerative joint disease, avascular necrosis (AVN), synovial disease, instability, internal and external snapping hip, and joint sepsis have all been treated with this approach in the literature.[7, 8, 9]  The application of hip arthroscopy to the treatment of extra-articular issues, including hip abductor tears and other peripheral and posterior compartment pathologic conditions, has expanded greatly as well. Arthroscopy has also been used after total hip arthroplasty (THA) and hip resurfacing in some cases.[10, 11, 12]

Careful patient selection is paramount for achieving good outcomes after hip arthroscopy. Systemic illness, local wounds, and infection are all contraindications for the procedure. Disorders that affect bone strength or restrict joint mobility may affect the ability to access the joint. Bone must be able to withstand the traction forces of the procedure, and the joint must be mobile enough to allow distraction and manipulation.

Advanced arthritis and degenerative joint disease may be contraindications, but the level of disease that a patient may have while remaining capable of being helped by surgical treatment is still a matter of debate.[13] Significant obesity may be a contraindication in some patients whose habitus exceeds the physical limits of the surgical instruments.[8, 14, 9, 12]

Anatomy

Proper portal placement for hip arthroscopy depends on an understanding of the anatomy about the hip. Anterior and medial structures to be taken into account include the femoral artery, the femoral vein, and the femoral nerve (see the images below); typically, these are 3.2 cm from the anterior portal.[15] Posteriorly, the sciatic nerve lies 2.9 cm from the posterior portal; it may be at risk if the portal drifts too far that direction. Superiorly, the superior gluteal nerve and artery lie 4.4 cm from the anterior and posterior lateral portals.

More anteriorly, the lateral femoral cutaneous nerve (LFCN; see the images below), along with its terminal branches, lies closer to a portal than any other significant neurovascular structure and is the most commonly affected nerve in terms of complications. A study by Byrd et al found that the anterior portal came within 0.3 cm of LFCN branches.[15, 16]

Best practices

Because hip arthroscopy is still a relatively new procedure, opinions continue to vary with regard to several aspects of its performance. A 2015 article on best practices surveyed 27 high-volume hip arthroscopists and reported the following results[17] :

• Position and setup - 100% used the supine position and employed fluoroscopy for initial access
• Procedures done by the group - Labral repair, 100%; FAI correction, 100%
• Anchors used - Knotless, 59%; knotted, 30%; both, 11%
• Capsule closure - Always, 11%; never, 11%; decision based on findings and underlying condition, 78%
• Postoperative bracing -  Routine, 29.6%; in some cases, 29.6%; never, 40.7%; average time of bracing, 3.4 weeks
• Weightbearing after the procedure - 92.5% limited weightbearing after surgery for a mean of 2.1 weeks
• Postoperative intra-articular injections - Local anesthetic, 55.6%; platelet-rich plasma (PRP), 7.5%; nothing, 37% 
• Heterotopic ossification prophylaxis - 100% prescribed some form of prophylaxis for 3 weeks after the procedure, either a nonsteroidal anti-inflammatory drug (NSAID; 89%) or aspirin (11%)

A systemic review that examined surgical treatment of FAI documented reduction of pain and improvement of function in 68-97% of patients.[18] Success has also been reported in athletic populations, with 75% of athletes returning to the same level of competition.[19] Many studies of long-term outcomes are currently under way. Although it has been theorized that surgical intervention may have an effect on the natural history of FAI as it relates to osteoarthritis of the hip, such intervention cannot be recommended for prophylaxis in asymptomatic hips.[20, 21]

Full informed consent addressing the specific pathology present and procedure to be performed should be obtained in every case.

A detailed history, a thorough physical examination, and careful critical assessment of diagnostic imaging results are extremely important in planning for hip arthroscopy. Depending on the indication, plain radiography, computed tomography (CT) with or without three-dimensional (3D) reconstruction, magnetic resonance imaging (MRI), MRI arthrography, or various combinations thereof may be part of a preoperative workup.

Traction tables are most commonly used for positioning and assist in gaining access to the hip joint. Tables specifically designed for hip arthroscopy are commercially available. The hip table and positioning should allow flexion, extension, abduction, and internal and external rotation. Instruments and implants suitably sized for the hip should be readily available to the surgeon. A 70º arthroscope is typically used for the procedure, and a 30º scope should be available.

Anesthesia

General or regional anesthesia can be used. General anesthesia is often used with anesthetic paralysis to assist with distraction of the hip joint. Femoral nerve blocks have been investigated as an adjunct for postoperative pain relief.[22, 23]

Positioning

Hip arthroscopy has been done in both the lateral decubitus position and the supine position; to date, the latter has been more commonly employed.[17]

Traction is placed on both the well leg and the leg to be operated on. Careful padding and secure fixation of the ankle in the traction device are important both for preventing peripheral nerve injury and for ensuring that traction force can be dependably applied without slipping. Close attention should be paid to positioning the traction post laterally against the medial thigh; this provides a more ideal traction vector for hip access and removes pressure on the pudendal nerve (thereby avoiding neurapraxia).

As noted, the patient should be positioned on the table in such a way as to permit flexion, extension, abduction, and rotation (internal and external). There should be sufficient room for C-arm positioning, and the C-arm and arthroscopy monitors should be readily visible. In many cases, 50 lb (22.7 kg) of traction is required to distract the hip. Prolonged traction (ie, >2 hours) may place the patient at increased risk for neurovascular complications, typically neurapraxias.[3, 7, 14, 9]

Standard intraoperative monitoring is indicated. Dropping temperature, falling blood pressure, and increasing abdominal firmness can be signs of intra-abdominal compartment syndrome; these parameters should be checked at regular intervals throughout the procedure. After the operation, follow-up at regular intervals is warranted for wound care, advancement of weightbearing, and rehabilitation, depending on the specific procedure that was performed. 

After the patient is properly positioned but before traction is applied, a systematic fluoroscopic examination should be performed first with the leg in extension in neutral, internal, and external rotation and next with the leg in 45º of flexion. Intraoperatively, the same views can be obtained and compared with the preoperative equivalents so that bony resection can be better judged.[24]  The hip area is then prepared and draped in the standard fashion. 

After traction is applied, an anterolateral portal is first identified, just over the anterosuperior margin of the greater trochanter. Portal placement must be done carefully, with care taken not to injure nearby neurovascular structures (see Technical Considerations).

Careful positioning and padding can help avoid traction-induced or compressive injuries to the obturator, pudendal, and peroneal nerves or branches thereof. The application of traction methods that do not use a padded perineal post and thus avoid perineal compression may reduce the risk of traction-related injury; however, larger-scale studies with longer follow-up will be required to establish the utility of these methods.[4]

Marking the border of the greater trochanter and the anterior superior iliac spine (ASIS) can help identify anatomic landmarks. Drawing a line from the ASIS longitudinally down the leg should help ensure that no portal is placed medial to the line, thus minimizing major risk to the femoral nerve. (See the image below.)

A spinal needle is used to localize the portal under fluoroscopic guidance. The needle is placed intra-articularly and repositioned by means of either a venting or a saline-distention technique so as to avoid chondral damage to the head or prevent labral penetration.[25, 26]  A nitinol wire is then placed though the spinal needle and into the acetabular fossa. The skin is carefully nicked so as to avoid damaging sensory nerves.

A cannulated obturator—and, in some cases, a series of dilators—is used to place the first portal. Placement of the next portal may vary to some degree, depending on the individual surgeon's preference. A traditional anterior portal is made at the junction of the line drawn longitudinally from the ASIS down the thigh and a perpendicular line drawn from the superior margin of the greater trochanter. Modified versions of this portal may be placed slightly more laterally or distally than the traditional portal.

Next, a spinal needle is introduced under direct vision from the anterior portal, between the femoral head and the labrum. A nitinol wire is introduced though the needle, and a cannulated portal is brought in under direct vision. Any cloudy blood that may be present can be cleared out at this point. Posteriorly, a posterior portal can be made in the same manner off the posterior superior corner of the greater trochanter.

An arthroscopic knife or cautery device is then used to create a capsulotomy between the anterior and anterolateral portals. The anterior and anterolateral portals will have to be switched to complete the capsulotomy.

After complete access has been obtained, a systematic 23-point diagnostic examination is carried out. Any of several accessory portal variants, such as the distal anterolateral accessory (DALA) portal or the midanterolateral portal, may be needed, depending on the additional procedures to be performed.[7, 8, 14, 15, 16, 12]  After the central compartment procedure is complete, traction is released and the hip is flexed to approximately 45º so as to relax the capsule. If the peripheral compartment cannot be completely accessed, a T-capsulotomy can be done, after which the 23-point examination can be completed.

The labrum can be inspected for tearing and chondrolabral separation. The labrum can be addressed with either partial or, in some cases, full takedown and repair. Repair takes the form of either a wraparound repair or a labral-base repair. Some studies have suggested that labral-base repair has a biomechanical advantage with more normal head contact; however, a comparative study found no difference in outcomes between labral-base repair and wraparound repair.[27]  (See the images below.)

Before repair of the labrum, the existing pincer is carefully assessed and resected. Preoperative imaging can help the surgeon judge the extent and nature of resection necessary. 

Traction is released, and the hip is flexed to approximately 45º. The peripheral compartment is evaluated. Commonly, the cam lesion, when present, is assessed and addressed at this point. (See the images below.) Rotation of the hip can facilitate access to the cam lesion. Delineation of the planned resection can be done with an articular curette. A motorized burr is used to resect the cam lesion and recontour the head-neck offset, tapering this to the femoral neck. Flexion of the hip can be used to check for any remaining impingement, and fine-tuning resection can be done from that point.

Repair of the capsule has become more popular and has some potential advantages, including avoidance of micro or macro instability. [28]

Intraoperative fluoroscopy can help the surgeon judge an intraoperative resection through comparison with equivalent preoperative views. Intra-articular injection of a local anesthetic may be employed for pain relief after the procedure. 

Hip arthroscopy is generally an outpatient procedure. Depending on the procedure, bracing can be used for 2-6 weeks after surgery if there is concern that excess range of motion (ROM) may damage the repair or contribute to instability. If resection gives rise to concern about possible stress fracture or femoral neck fracture, limitations on weightbearing may be imposed, generally for 2-6 weeks after surgery.

Physical therapy is generally initiated as soon as possible postoperatively. Passive ROM with continuous passive motion (CPM) or an exercise bike is initiated as soon as possible as well. These early measures can help prevent arthrofibrosis and adhesive capsulitis.

A nonsteroidal anti-inflammatory drug (NSAID) or aspirin is administered for at least 3 weeks to minimize risk of heterotopic ossification. Postoperative follow-up visits are scheduled at regular intervals for checking wound status and advancing rehabilitation. 

In a prospective multicenter study by Larson et al, complication data were compiled for 1615 hip arthroscopies (including both revision [n = 128] and primary procedures [n = 1487]).[29]  The overall complication rate, not counting transient nerve issues, was 8.3%. Higher rates were reported for female patients and for cases involving longer traction times (>60 minutes). Rates for specific complications included the following:

• Periportal sensory disturbance, 16.5% (mostly transient)
• Perineal numbness, 1.4%
• Iatrogenic chondral injury, 1.2%
• Superficial portal infection, 1.1%
• Iatrogenic labral puncture, 0.9%
• Foot sensory defect, 0.8%
• Heterotopic ossification, 0.8%
• Deep vein thrombosis (DVT). 0.1%
• Pulmonary embolism (PE), 0.1%
• Femoral neck stress fracture, 0.1%

Other serious complications reported in the literature have included avascular necrosis (AVN), abdominal compartment syndrome, and iatrogenic instability[30, 31] ; however, these were not observed in the study by Larson et al.[29]

The goals of pharmacotherapy are to reduce morbidity and prevent complications. A standard-dose nonsteroidal anti-inflammatory drug (NSAID) or aspirin is used for prophylaxis of heterotopic ossification for at least 3 weeks after hip arthroscopy. 

Class Summary

NSAIDs have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known, but they may inhibit cyclooxygenase (COX) activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.

Ibuprofen (Advil, Motrin, Caldolor)

Ibuprofen is the drug of choice for patients with mild-to-moderate pain. It inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Naproxen (Aleve, Anaprox, Anaprox DS, Flanax Pain Relief, Mediproxen)

Naproxen is used for the relief of mild-to-moderate pain. It inhibits inflammatory reactions and pain by decreasing COX activity, which results in decreased prostaglandin synthesis.

Ketoprofen (Active-Ketoprofen)

Ketoprofen is used for relief of mild-to-moderate pain and inflammation. Small dosages are indicated initially in small patients, elderly patients, and patients with renal or liver disease. Doses higher than 75 mg do not increase the therapeutic effects. Administer high doses with caution, and closely observe the patient’s response.

Aspirin (Bayer Aspirin Extra Strength, Aspercin, Ascriptin Regular Strength, Bufferin, Durlaza)

Aspirin blocks prostaglandin synthetase action, which in turn inhibits prostaglandin synthesis and prevents the formation of platelet-aggregating thromboxane A2; it acts on the hypothalamic heat-regulating center to reduce fever.

Indomethacin (Indocin, Tivorbex)

Indomethacin is thought to be the most effective NSAID for the treatment of AS, though no scientific evidence supports this claim. It is used for relief of mild-to-moderate pain; it inhibits inflammatory reactions and pain by decreasing the activity of COX, which results in a decrease of prostaglandin synthesis.