Synovial-Based Disorders

DEFINITION

Synovial-based disorders about the hip are relatively rare entities. Synovial chondromatosis and pigmented villonodular synovitis (PVNS) have been increasingly of interest to hip arthroscopists and will be the primary focus of this chapter. Inflammatory arthropathies and septic arthritis will also be discussed, as they are often grouped with the cited conditions and are amenable to similar surgical interventions.

Synovial chondromatosis is a benign, typically monoarticular neoplastic process characterized by nodular cartilaginous proliferation arising from the synovial tissue of joints. Hyaline cartilage nodules initially form within synovial tissue, progressively enlarge, and eventually detach from the synovium. This repetitive process may result in numerous intra-articular loose bodies and is known as primary disease. Secondary synovial chondromatosis differs in that a preexisting joint pathology causes similar intra-articular loose bodies.

PVNS is a proliferative process of unclear etiology that results in chronic inflammation and characteristic hemosiderin deposition within the synovium. PVNS can be either focal, involving only a portion of a given joint's synovium, or diffuse, involving the entirety of a joint's synovial tissue.

 

 

ANATOMY

 

Synovium is a highly specialized tissue that lines the intraarticular structures of a joint. It is composed of two to three layers of synoviocytes covered by a loose connective tissue composed of collagen, fat, and blood vessels.

 

In addition to acting as a mechanical shock absorber, the synovium also produces synovial fluid and hyaluronic acid, which together provide nourishment and lubrication to the articular surface.

 

The hip joint is represented by the articulation between the head of the femur and the acetabulum of the pelvis. The femoral head is deeply recessed within the acetabulum, creating an inherently stable joint.

 

In addition to the relatively constrained bony anatomy, a thick fibrous capsule with ligamentous condensations (pubofemoral, iliofemoral, and ischiofemoral ligaments) provides further stability to the hip joint, particularly in terminal range of motion.

 

The hip joint is further covered by a large soft tissue envelope consisting of muscular, tendinous, and neurovascular structures.

 

The complex anatomy of the hip can be divided into three compartments, which are relevant when discussing arthroscopic treatment of various hip pathologies (FIG 1):

 

Central compartment, which consists of the capsule, acetabular labrum, acetabulum, femoral head, and

ligamentum teres. Together, these structures are often referred to as the hip joint proper.

 

Peripheral compartment, the structures of which are described as extra-articular, however, remain intracapsular. The zona orbicularis is considered the quintessential landmark of the peripheral compartment and is a thickening in the hip capsule, which wraps circumferentially around the femoral neck. Other landmarks in the peripheral compartment include the medial and lateral synovial folds, the psoas tendon, and the femoral head-neck junction.

 

The lateral synovial fold contains the intracapsular penetrating arteries, which provide the major blood supply to the femoral head.

 

Lateral/peritrochanteric compartment, which is the space between the proximal femur and the iliotibial band. Structures that can be visualized within this compartment include the insertion of the gluteus maximus, medius, and minimus tendons and the proximal vastus lateralis.

 

Synovial disorders can arise and/or extend into any of the mentioned compartments and complete, systematic evaluation of all three compartments is indicated when performing hip arthroscopy for synovial pathologies.

 

PATHOGENESIS

 

Synovial chondromatosis may exist in three temporal phases as described by Milgram.6 During phase I, the synovial disease is active in the production of nodular cartilaginous proliferations; however, no intra-articular loose bodies are present. Phase II involves continued synovial proliferation with the presence of loose bodies within the joint. The synovium becomes quiescent in phase III; however, the loose bodies remain.

 

The intra-articular loose bodies may result in mechanical injury to the chondral surfaces of the femoral head and/or the acetabulum via third-body wear.

 

Synovial chondromatosis may also affect the bursae and tendon sheath of large joints, which around the hip include the psoas tendon and bursa.

 

Loose bodies can be numerous with one recent study showing an average of 42 (range 7 to 220) loose bodies in 11 patients treated arthroscopically for synovial chondromatosis (FIG 2).12

 

PVNS is an idiopathic, monoarticular reactive synovial disease that has been described as either a nodular or diffuse pattern. It is characterized by proliferation of synovial villi and nodules. This process leads to joint destruction via several mechanisms, including recurrent hemarthroses and chronic inflammation leading to caustic damage to the articular surface as well as loose body formation, which may lead to mechanical damage similar to synovial chondromatosis.

 

 

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FIG 1 • The three arthroscopic compartments of the hip with important margin defining structures.

 

 

The constrained nature of the hip makes it more susceptible than other joints to bony erosion and destructive changes in the course of synovial disorders.

 

Chondrocalcinosis can be encountered and is important to recognize. It is most frequently caused by calcium pyrophosphate dihydrate (CPPD) crystal deposition within a particular joint. This is often characterized by crystalline deposition within the acetabular labrum and/or the articular cartilage.

 

NATURAL HISTORY

 

 

 

Three distinct phases of synovial chondromatosis have been described: Early: active synovial disease and the absence of loose bodies Transitional: active synovial disease with loose bodies

 

Late: cessation of active synovial disease with loose bodies

 

Although synovial chondromatosis is self-limited in some cases, progressive disease leading to osteoarthritis is of primary concern when developing a management strategy. Prompt removal of loose bodies and inflamed synovium is important for both symptomatic relief and prevention of long-term complications.

 

There is a 5% reported incidence of conversion to synovial chondrosarcoma, which should be suspected with atypical presentation such as rapid onset, extra-articular involvement, and multiple recurrences.

 

Patients with PVNS often present in a delayed manner, after joint degenerative changes have already begun. Due to the higher likelihood of articular destruction at presentation, synovectomy alone is less likely to result in substantial clinical improvement.

 

Chondrocalcinosis results in crystalline deposition into the acetabular labrum and the articular cartilage, thus altering the mechanical properties making them more susceptible to breakdown.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Patients who present with synovial disorders often have vague complaints that are insidious in onset. These complaints include pain that is typically worse with activity, stiffness, swelling, joint instability and mechanical symptoms, such as locking and catching. Deep groin and deep lateral hip pain are also common presenting complaints associated with synovial disease involving the hip joint.

 

The spectrum of synovitis can be distinguished from septic arthritis by the absence of rapidly progressing pain, extreme irritability with movement, and constitutional symptoms. The distinction is of the utmost importance as joint sepsis necessitates emergent intervention.

 

 

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FIG 2 • Numerous loose bodies arthroscopically recovered from a single hip joint of a patient with synovial chondromatosis.

 

A reported history of trauma to the joint is sometimes present in patients with PVNS; however, a direct correlation has not been convincingly established.

 

Physical examination findings are similar for all benign synovial disorders and can be the result of synovial inflammation, loose body impingement, or the degenerative joint changes evident in later stage disease. Most common general findings include decreased range of motion, erythema, warmth, and tenderness to palpation about the affected joint. It should be noted that swelling and other superficial physical examination findings are often absent in hip synovitis due to the large soft tissue envelope around the joint.

 

Hip examination often reveals pain with range of motion that is most pronounced at the terminal ranges of motion. Decreased range of motion is also common secondary to inflammation and/or capsular distension from the loose bodies.

 

Examination maneuvers that may be positive include Patrick (FABER) test, anterior impingement test, and abduction internal rotation test (see Exam Table).

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Imaging studies are the most reliable way to distinguish among the various benign synovial disorders as well as identify other possible causes of hip symptomatology with several characteristic findings described.

 

Anteroposterior and lateral (cross-table, frog-leg, and Dunn view) radiographs of both hips are the preferred initial series, especially for the evaluation of associated femoroacetabular impingement morphology.

 

Plain film radiographic results can range from a normal x-ray to one showing either multiple loose bodies (FIG 3)

 

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or degenerative changes depending on the disease process and/or stage.

 

 

 

FIG 3 • Anteroposterior x-ray of the pelvis from a patient with synovial chondromatosis. Note the loose bodies about the left hip.

 

 

 

 

FIG 4 • A T2-weighted magnetic resonance image of the pelvis showing multiple loose bodies in the left hip of a patient with synovial chondromatosis.

 

 

When present, periarticular erosions and reciprocal bony lesions often without evidence of articular involvement are x-ray findings suggestive of PVNS.

 

The majority of patients with PVNS, however, have no findings on initial plain x-ray.

 

Magnetic resonance imaging (MRI) (FIG 4), computed tomography (CT), and/or arthrography may be helpful if loose bodies are suspected and not seen on plain films, as is often the case early in the disease process prior to the calcification of nodules and/or loose bodies.

 

In general, magnetic resonance arthrography is considered the gold standard for assessing hip soft tissue pathology as well as intra-articular, nonossified loose bodies.

 

MRI findings consistent with PVNS include similarity of lesion appearance on both T1- and T2-weighted images. This is classically referred to as a dark-on-dark appearance and is due to the high hemosiderin content (FIG 5).

 

Despite the crucial role of imaging in the diagnosis of synovial disorders, many cases of PVNS, synovial chondromatosis, and their associated loose bodies are first appreciated during arthroscopy. Nearly 50% of

patients who underwent hip arthroscopy for synovial chondromatosis in a 2011 study by Marchi et al5 were not diagnosed with preoperative imaging, which included gadolinium-enhanced MRI.

 

Arthrocentesis is generally not recommended in patients with suspected synovial disorders unless one is concerned for infection or crystalline arthropathy. When performed, synovial fluid most often appears brown stained in patients with PVNS and a normal clear or straw color in most cases of synovial chondromatosis.

 

Laboratory values such as complete blood count, erythrocyte sedimentation rate, and C-reactive protein are often normal in most cases of synovitis and should be analyzed when one is concerned for an infectious process.

 

DIFFERENTIAL DIAGNOSIS

 

 

 

Primary villonodular synovitis Synovial chondromatosis Septic arthritis

 

 

 

FIG 5 • A. T1- and (B) T2-weighted sagittal magnetic resonance images of a right hip demonstrating a focal PVNS lesion along the anterior aspect of the distal femoral neck; also appreciated is a large joint effusion.

 

 

 

Hemarthrosis Lipoma arborescens

 

 

Synovial hemangioma Tumoral calcinosis

 

 

Crystalline arthropathy (gout/pseudogout/chondrocalcinosis) Inflammatory arthropathy (rheumatoid arthritis)

NONOPERATIVE MANAGEMENT

 

In patients who have mild symptoms and retained range of motion, observation with careful monitoring can be considered. However, most patients with benign synovial disorders have endured a significant delay in

diagnosis and as a result have failed conservative management at the time of presentation to the orthopaedic surgeon.

 

Although studies involving the hip joint are lacking, PVNS has been shown to be responsive to radiation therapy in the form of both external beam and intra-articular injection of radioactive isotopes, which can be

used to achieve a result similar to surgical synovectomy in the knee.7 More recently, this modality has been advocated as an adjunct to surgical management to reduce the incidence of recurrence.9

 

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SURGICAL MANAGEMENT

 

The goal of surgical management is to remove all abnormal synovium to improve symptoms as well as

eliminate or lower the possibility of recurrence while reducing pain and minimizing the risk of joint destruction.

 

Although open approaches have been traditionally used for surgical management, arthroscopy has been recently employed to accomplish the mentioned goals while at the same time avoiding the potential complications and prolonged recovery of an open procedure, surgical dislocation, and/or radiation.

Arthroscopic procedures may also allow for a potentially faster recovery given the less invasive nature of the approach. However, open surgery may be indicated and favorable in cases of nonfocal, diffuse PVNS with extension in both intra- and extra-articular compartments to avoid the risk of recurrence secondary to an incomplete synovectomy.

 

Arthroscopy with direct visualization of nonossified loose bodies and synovial biopsy is considered an important diagnostic tool and can be an indication for surgery when the diagnosis is questionable and hip pain is refractory to conservative management.

 

Historically, inferior results with arthroscopic synovectomy of the hip have been attributed to older techniques that were not performed under traction and failed to access the central compartment. Improvement in capsular management with interportal and extensile capsulotomy have improved the visualization and instrumentation of

the central and peripheral compartments with an arthroscopic approach (FIG 6).1

 

It is important to note that arthroscopic synovectomy and loose body removal are often performed in conjunction with labral repair and osteoplasty, depending on concomitant pathology present at the time of surgery.

 

 

 

FIG 6 • An extensile capsulotomy before (A) and after repair (B). Gross anatomy around the hip capsule demonstrated using cadaveric specimen (C).

 

Preoperative Planning

 

Preoperative imaging, including radiographs and advanced images (CT, MRI, etc.), should be reviewed to determine the compartment(s) in which loose bodies are most likely to be found. This information is critical to select an open or arthroscopic approach and to assure the capsule is managed accordingly to permit thorough visualization and instrumentation.

 

Review of imaging and physical examination findings should also include assessment for other hip pathology such as cam- and/or pincer-type femoroacetabular impingement morphology or labral tears, which can be addressed at the time of arthroscopy. Conversely, many cases of synovial disease are encountered and addressed during the treatment of femoroacetabular impingement.

 

Preoperative risk assessment and medical clearance should also be performed for select patients who have other medical disorders that place them at risk for general anesthesia.

 

Positioning

 

Historically, hip arthroscopy has been described in both the supine (FIG 7) and lateral positions (FIG 8).

 

Supine positioning is most commonly achieved on a fracture table setup that allows for axial traction. Both feet are placed in well-padded traction boots or similar retention devices and a well-padded perineal post, which is positioned between the patient's legs and slightly lateralized to favor the operative side. This placement avoids placing direct pressure on the pudendal nerve and provides a lateralized vector to the proximal femur to assist with joint distraction. The nonoperative leg is first positioned in approximately 45 to 60 degrees of abduction

and neutral flexion/extension

 

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and rotation. We prefer to initially place the operative leg in a similar amount of abduction with manual axial traction. After locking the traction in place, the operative leg is then adducted to neutral while keeping the hip in approximately 0 to10 degrees of flexion. This positioning allows for both the axial traction and the lateralization required to achieve the required amount femoral head-acetabulum distraction. Traction must be applied judiciously, taking care to achieve the minimum joint distraction and for the minimum duration needed for safe instrumentation to minimize risk of iatrogenic chondral injury.

 

 

 

 

FIG 7 • Positioning and room setup for performing hip arthroscopy with the patient supine.

 

 

The surgeon and the assistant(s) are best positioned on the operative side, with the arthroscopic equipment positioned across the table on the nonoperative side.

 

The C-arm of the fluoroscopic machine is draped sterilely and can either be positioned between the patient's legs or perpendicular with the body from the opposite side of the operative hip. Between the legs is often preferred to allow for unencumbered lateral fluoroscopic images of the operative hip. The fluoroscopic viewing

screen is often best positioned near the foot of the bed or directly across from the surgeon, depending on the location of the C-arm.

 

Lateral positioning is accomplished by placing the patient in the lateral decubitus position on a well-padded operating table with the operative side up; an axillary roll should be used. Hip posts are then used to stabilize the pelvis and prevent undesired motion during the procedure. The operative foot is also placed in a well-padded traction boot.

 

As with supine positioning, a well-padded perineal post is placed with minimal to no contact with the nonoperative leg, with similar attention given to avoiding pressure on the pudendal nerve and perineum as well as providing a joint distraction vector.

 

The starting position places the leg in neutral rotation and 15 degrees of flexion and abduction. This provides maximal relaxation of the hip capsule, which aids in visualization.

 

The surgeon may elect to stand either at the anterior or posterior aspect of the patient with the assistant across the table and the scrub technician on the operative side.

 

The fluoroscopic C-arm is positioned with the apex under the table at the level of the greater trochanter just proximal to the operative team with the monitor near the foot of the bed opposite the surgeon.

 

Approach

 

Although the majority of hip arthroscopy procedures involve systematic inspection of all compartments, the approach and portal placement largely depend on the planned procedure that is going to be performed.

 

Regardless, portal placement is the key to successful hip arthroscopy.

 

Central compartment: Commonly used portals include the anterior, midanterior, anterolateral, midanterolateral, and posterolateral portals.

 

 

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FIG 8 • Positioning and room setup for performing hip arthroscopy with the patient lateral.

 

 

Peripheral compartment: anterolateral, midanterior, posterolateral, distal anterolateral accessory, accessory anterolateral, and superolateral

 

Peritrochanteric compartment: anterolateral, anterior, posterolateral, proximal anterolateral accessory, distal anterolateral accessory, peritrochanteric space, and auxiliary posterolateral

 

 

 

FIG 9 • Artist depiction of a left hip with labeled surface landmarks and portal placements. ASIS, anterior superior iliac spine; AP, anterior portal; AL, anterolateral; PL, posterolateral; MAP, midanterior portal; PMAP, proximal midanterior portal; PALA, proximal anterolateral accessory; DALA, distal anterolateral accessory; PSP, peritrochanteric space.

 

Portals

 

Anterolateral (FIG 9)

 

 

Placed 1 cm superior and anterior to the palpated tip of the greater trochanter

 

The superior gluteal nerve and lateral femoral cutaneous nerve are the structures most at risk during this portal placement.

 

 

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Posterolateral (see FIG 9)

 

 

Placed 1 cm superior and posterior to the palpated tip of the greater trochanter

 

 

The sciatic nerve is the structure at greatest risk during this portal placement. To reduce the risk of sciatic nerve injury, external rotation and excessive hip flexion should be avoided when placing this portal.

 

Anterior (see FIG 9)

 

 

Placed 1 cm lateral to the anterior superior iliac spine (ASIS) and in line with the anterolateral portal

 

The lateral femoral cutaneous nerve and ascending branch of the lateral femoral cutaneous artery (LCFA) are most at risk during this portal placement.

 

Midanterior (proximal and distal) (see FIG 9)

 

Made at a point both proximal and distal to the anterior and anterolateral portal that is both equidistant and midway between the aforementioned portals

 

The ascending branch of the LCFA is the structure most at risk during placement of this portal.

 

Accessory anterolateral (see FIG 9)

 

 

 

Placed 3 to 5 cm directly distal to the anterolateral portal Proximal anterolateral accessory (see FIG 9)

 

Placed laterally in line with the anterior border of the femur directly posterior to the proximal midanterior portal

 

Peritrochanteric space (see FIG 9)

 

 

 

Placed laterally in line with the anterior border of the femur at the level of the distal midanterior portal Distal anterolateral accessory (see FIG 9)

 

Placed laterally in line with the anterior border of the femur at a point distal to the peritrochanteric space portal that is equal to the distance between the proximal anterolateral accessory and the peritrochanteric space portals

 

 

TECHNIQUES

• Portal Positioning

  Prior to any portal placement, the surgeon must ensure proper patient positioning as well as adequate joint distraction to replicate safe access.

  Palpate and mark the surface landmarks: the anterior, superior and posterior aspects of the greater trochanter, and the ASIS (see FIG 9).

• Portal Placement under Traction

  The anterolateral portal is generally placed first while the hip is in traction.

  Confirm portal position and trajectory under fluoroscopy by placing a spinal needle on the skin aiming toward the center of the hip joint.

  The spinal needle is advanced under fluoroscopic assistance, aiming for the distal one-third of the space between the acetabular rim and the femoral head, being sure to keep the needle parallel or with a slightly posterior trajectory toward the floor. Proper trajectory ensures safe access without inadvertent damage to the acetabular labrum or articular cartilage of the femoral head.

  Once the spinal needle passes through the capsule, the stylus is removed, which generally results in an air arthrogram when a fluoroscopic image is obtained. A flexible guidewire is then passed through the spinal needle, and the spinal needle is removed.

  Using a no. 11 blade, a 5-mm incision is made over the guidewire to accommodate a blunt cannulated trocar, which is then placed over the guidewire into the hip joint. It is important to insert the trocar using slow constant pressure in a twisting fashion to aid with breach of the capsule as well as to avoid inadvertent articular cartilage damage. Care must be taken not to fracture the guidewire.

  Once the anterolateral portal is positioned, the camera is introduced, and the anterior or midanterior portal is performed under direct visualization.

   

  Generally, the anterior or midanterior portal is placed next under direct arthroscopic visualization.

   

  The arthroscope is positioned in the anterolateral portal and directed anteriorly to visualize the anterior triangle, which is formed by the junction of the femoral head, acetabular labrum, and the top of the field of visualization. The anterior or midanterior portal should enter this anterior triangle for optimum working use.

   

  Once the spinal needle enters the joint through the anterior triangle, the spinal needle trocar is removed, and the guidewire is threaded into the joint. The spinal needle is removed, the skin is incised proximal and distal to the guidewire with a no. 11 blade, and a curved hemostat is used to spread the tissues deep to the incision in order to avoid injury to the lateral femoral cutaneous nerve.

   

  The arthroscopic cannula with a cannulated trocar is then passed along the guidewire with direct visualization of the entry into the joint.

   

  The camera is then switched into the newly created anterior or midanterior portal in order to visualize and confirm the previously placed anterolateral portal and ensure proper placement distal to the labrum.

   

  The posterolateral portal, if desired, is placed last under direct arthroscopic visualization in the same fashion as the anterior portal, taking care to avoid labral penetration or injury to the femoral head. This can often be used as an outflow portal in cases of significant synovial inflammation and friable, hemorrhagic tissue.

   

   

  Leg position is critical when placing this portal, as external rotation and/or flexion of the hip places the sciatic nerve at greater risk.

   

• Evaluation of the Central Compartment

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  The majority of surgeons use a 70-degree arthroscopic lens for hip arthroscopy; however, a 30-degree arthroscopic lens may also benefit full visualization.

   

  The anterolateral portal is the primary visualization portal for the central compartment. Via this portal, the surgeon is able to visualize the acetabular labrum, medial femoral head, acetabular fossa, ligamentum teres, and pulvinar.

   

  Synovial pathology and loose bodies are often found in the acetabular fossa and should be removed and/or débrided at this time using accessory portals to facilitate required instrumentation, including shavers, biters, and graspers.

   

  The anterior, midanterior, and posterolateral portals may also be of benefit for full diagnostic evaluation and treatment of pathologic synovium and/or loose bodies.

• Evaluation of the Peripheral Compartment

   

  Access to the peripheral compartment can be easily achieved using the same portals that were used to assess the central compartment. Notably, work in this compartment can be accomplished without the use of traction.

   

  The portal in use should be redirected inferiorly along the anterior femoral neck; this can be accomplished via direct visualization and under fluoroscopic guidance.

   

  Flexing the hip reduces tension on the capsule and ligamentous structures and is preferred by some surgeons when working in the peripheral compartment. The iliofemoral ligament can be retracted and preserved in this fashion.

   

  Evaluation should proceed in a systematic fashion and often involves placing the hip in varying degrees

  of rotation, abduction, and flexion to gain access to the entire compartment.

   

  First, one can visualize the zona orbicularis, anterior and medial synovial folds, and then move caudal to bring the inferior reflection of the joint capsule into view.

   

  Advancing the arthroscope inferiorly over the medial synovial fold will allow for visualization of the inferior bony structures (the femoral neck and inferolateral femoral head) as well as the anteroinferior labrum and the transverse acetabular ligament.

   

  Sweeping cranially, the anterior labrum, anterolateral femoral head, superolateral femoral head, and superior labrum can be fully visualized.

   

  Lastly, one can advance the arthroscope over the femoral neck to visualize the lateral synovial fold. One can pass the arthroscope between zona orbicularis and the lateral synovial fold in order to visualize the posterior femoral neck and capsule as well as the posterolateral femoral neck.

• Evaluation of the Peritrochanteric/Lateral Compartment

   

  To access the peritrochanteric space, the hip should be placed in neutral rotation and extension as well as in slight abduction to relieve tension on the iliotibial band and open up the lateral compartment.

   

  Access, viewing, and working portals are generally anteriorly based; however, lateral and even posterior portals may be needed depending on the pathology being addressed. Simple débridement, however, rarely necessitates these accessory portals.

   

  In general, the entirety of the compartment is easily visualized after distention with arthroscopic fluid and superficial débridement by simply sweeping the arthroscope in all directions. A thorough bursectomy is often critical to assure complete visualization and avoid missing occult loose bodies, abductor tears, or other pathology.

   

  Access to the peritrochanteric compartment may also be needed to address any synovitis that has invaded or loose bodies that have migrated into this space. Additionally, peritrochanteric access is employed in some cases to address concomitant pathology such as gluteus medius tears, trochanteric bursitis, and iliotibial band snapping.

• Loose Body Removal

   

  The first and most important step in loose body removal is detection of their presence, which can be achieved by meticulous review of the preoperative imaging as well as systematic intraoperative assessment of the compartments of the hip as described earlier (TECH FIG 1A,B).

   

  Once identified, loose bodies may be removed in numerous ways. Regardless of the methods that are used to remove a given loose body, the ultimate goal is removal of all loose bodies within the joint without dislodging them in the soft tissue during extraction.

   

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  One traditional approach is to employ different strategies based on the size of the loose bodies. Smaller fragments can typically be removed with an arthroscopic shaver attached to suction. Medium-sized loose bodies are often easily removed with a hollow implement such as a large-bore cannula, which can be hooked to suction. Larger loose bodies may be more easily removed with a grasper (TECH FIG 1C).

  Finally, exceptionally large loose bodies may need to be broken in situ prior to being extracted.

   

   

   

  TECH FIG 1 • A. Loose bodies identified in the central compartment just prior to removal and (B) loose bodies surrounded by inflamed synovium in a patient with synovial chondromatosis. C. Intraoperative image of a large loose body within the jaws of an arthroscopic grasper just prior to removal.

   

   

  Several methods have been suggested using large-bore tubes and instruments borrowed from other surgical subspecialties with the goal of aiding with expeditious removal of the numerous loose bodies that can be present in synovial chondromatosis. The proposed benefit of these techniques is to limit traction time while effectively removing all loose bodies. In addition to standard arthroscopic shavers, cannulas, and graspers, implements previously described in the literature to aid in loose body removal include the following:

   

   

  Flexible endotracheal tube attached to suction8 Ureteric basket for direct retrieval11

• Synovectomy

   

  As with loose body removal, visualization of the entire hip joint is essential when performing synovectomy.

   

  Total or near total synovectomy must be carried out in a systematic fashion in each compartment. This can be achieved only by alternating working and viewing portals to view and ultimately access the entire hip joint.

   

  The majority of the synovectomy can be carried out using standard arthroscopic shavers.

  Synovial tissue in PVNS is known to be especially resistant to standard arthroscopy shavers and may require the use of more robust graspers and/or biters for full removal (TECH FIG 2).

   

  TECH FIG 2 • Focal PVNS lesion.

   

   

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  PEARLS AND PITFALLS

   

  Preoperative planning

• Be prepared for loose bodies of different sizes and in varying quantities, as it is not uncommon to discover loose bodies that were not previously identified on imaging.

   

  Concomitant pathology

• It is important to have appropriate instrumentation available to address concomitant pathology such as femoroacetabular impingement, labral tears, or peritrochanteric compartment pathology when it is encountered.

   

  Synovial débridement and removal

• Care should be taken when performing débridement near the lateral synovial fold to avoid damaging the penetrating capsular arteries.

   

  Finding loose bodies

• Although loose bodies can be found anywhere within the hip, common locations include the inferior recess and the acetabular fossa.

 

 

 

	Loose body ▪ Do not discount the use of unorthodox methods of loose body removal, as removal complete and timely removal is required for a successful outcome.

 

 

 

POSTOPERATIVE CARE

 

After synovectomy and/or loose body removal, the patient is kept non-weight bearing or toe-touch weight bearing for approximately 1 week postoperatively. Active range of motion of the hip is encouraged immediately.

 

Should a large interportal or T capsulotomy of the iliofemoral ligament be performed to facilitate loose body removal and/or synovectomy, a hip orthosis brace may be used to limit external rotation and tension of the capsular repair, for approximately 2 weeks.

 

Postoperative pain is typically effectively managed with a short course of oral narcotics.

 

Physical therapy focusing on hip range of motion and strengthening is indicated for most patients and should be performed for 6 to 12 weeks.

 

 

OUTCOMES

Studies that have investigated the outcomes of arthroscopic synovectomy and/or loose body removal have mainly focused on comparing both the efficacy and morbidity to that of open procedures. It is widely accepted that arthroscopy carries less morbidity and results in faster recovery as well as improved postoperative range of motion when compared to open procedures about the hip. Comparison of efficacy is, however, less clear, and arthroscopy should not be selected if limited exposure and access to the pathology results in an incomplete treatment of synovial pathology and a greater risk of recurrence.

Although the literature remains somewhat limited, a few studies have investigated the outcomes of arthroscopic synovectomy of the hip. One retrospective study looked at 120 consecutive cases of synovial chondromatosis with a mean follow-up of 78.6 months. The authors demonstrated that 63 patients (57%) had good to excellent results. Of note, 42 patients (38%) went on to open procedure, 23

(21%) required repeat arthroscopy, and 22 (20%) eventually went on to total hip arthroplasty.2

More recently, a small case series that followed 24 patients after arthroscopic synovectomy and loose body removal for synovial chondromatosis with a mean follow-up of 41 months showed good or excellent

outcomes in 75% of patients and symptomatic recurrence in 16.7%.4 Outcomes were measured using a validated hip score, clinical assessment tool, and activity scale (Harris hip score, visual analog score, and University of California, Los Angeles [UCLA] activity scale, respectively) in conjunction with preoperative and postoperative imaging.

Outcomes of total synovectomy alone as treatment of PVNS of the hip have not been historically favorable with high rates of conversion to arthroplasty within the follow-up period. One study reviewing 16 cases of which 8 were treated with synovectomy alone demonstrated a 50% rate of conversion to total

hip arthroplasty.10 This has been attributed to the high percentage of patients with degenerative changes at the time of presentation, which emphasizes the importance of patient selection. The morbidity of open

approaches may have also played a role in this high-failure rate. Recently, a case series by Byrd et al3 followed 13 patients after arthroscopic synovectomy of the hip for 2 to 10 years and demonstrated a statistically significant mean improvement in Harris hip scores and range-of-motion scores. Only one

patient (8%) went on to total hip arthroplasty, 6 years after arthroscopy.3

 

 

 

COMPLICATIONS

Arthroscopic synovectomy and loose body removal are often time-intensive procedures. Long operative times as well as prolonged traction times can lead to an increased risk of complications, which include the following:

Pudendal nerve—neurapraxia secondary to traction or compression injury due to local compression at the perineal post

Peroneal nerve—neurapraxia secondary to traction Sciatic nerve—neurapraxia secondary to traction Fluid extravasation

Abdominal compartment syndrome due to extravasation into the retroperitoneal and/or abdominal cavity

Femoral nerve palsy Neurologic injury

Superior gluteal nerve—direct trauma during anterolateral portal placement

Sciatic nerve—direct trauma during posterolateral portal placement

Lateral femoral cutaneous nerve—direct trauma during anterior or anterolateral portal placement Deep vein thrombosis

Iatrogenic articular cartilage damage

Heterotopic ossification

 

 

 

REFERENCES

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1. Bedi A, Galano G, Walsh C, et al. Capsular management during hip arthroscopy: from femoroacetabular impingement to instability. Arthroscopy 2011;27(12):1720-1731.

    

2. Boyer T, Dorfmann H. Arthroscopy in primary synovial chondromatosis of the hip: description and outcome of treatment. J Bone Joint Surg Br 2008;90(3):314-318.

    

3. Byrd JW, Jones KS, Maiers GP III. Two to 10 years' follow-up of arthroscopic management of pigmented villonodular synovitis in the hip: a case series. Arthroscopy 2013;29(11):1783-1787.

    

4. Lee JB, Kang C, Lee CH, et al. Arthroscopic treatment of synovial chondromatosis of the hip. Am J Sports Med 2012;40(6):1412-1418.

    

5. Marchie A, Panuncialman I, McCarthy JC. Efficacy of hip arthroscopy in the management of synovial chondromatosis. Am J Sports Med 2011;(39 suppl):126S-131S.

    

6. Milgram JW. Synovial osteochondromatosis: a histopathological study of thirty cases. J Bone Joint Surg Am 1977;59(6):792-801.

    

    

7. Park G, Kim YS, Kim JH, et al. Low-dose external beam radiotherapy as a postoperative treatment for patients with diffuse pigmented villonodular synovitis of the knee: 4 recurrences in 23 patients followed for mean 9 years. Acta Orthop 2012;83(3):256-260.

    

    

8. Randelli F, Randelli P, Banci L, et al. Intra-articular loose body removal during hip arthroscopy. Orthopedics 2010;33(7):476.

    

    

9. Shabat S, Kollender Y, Merimsky O, et al. The use of surgery and yttrium 90 in the management of extensive and diffuse pigmented villonodular synovitis of large joints. Rheumatology 2002;41(10):1113-1118.

    

    

10. Vastel L, Lambert P, De Pinieux G, et al. Surgical treatment of pigmented villonodular synovitis of the hip. J Bone Joint Surg Am 2005; 87(5):1019-1024.

     

     

11. Weinrauch P, Kermeci S, Lang A. The use of a ureteric stone basket for removing loose bodies at hip arthroscopy. Arthrosc Tech 2013; 2(3):e311-e313.

     

     

12. Zini R, Longo UG, de Benedetto M, et al. Arthroscopic management of primary synovial chondromatosis of the hip. Arthroscopy 2013; 29(3):420-426.