Arthroscopy for Structural Hip Problems

 

 

 

INTRODUCTION

 

The development and advancement of hip arthroscopy has facilitated the treatment of various conditions of the hip joint and surrounding structures through a minimally invasive approach. This chapter discusses the use of hip arthroscopy in structural problems of the hip and highlights indications, surgical techniques, postoperative rehabilitation, complications, and outcomes (Table 7-1).

 

INDICATIONS Arthroscopic surgery for structural hip problems is primarily focused on treating various forms of femoroacetabular impingement (FAI). Surgical treatment is indicated in those patients with symptomatic FAI who have failed a comprehensive nonoperative treatment program. FAI results from abnormal contact between the acetabular rim and the femoral neck during terminal range of motion (1). This abnormal contact causes pain and limited motion, leading to labral and chondral pathology and ultimately osteoarthritis (1,2). FAI can be caused by abnormal morphology of the acetabulum (pincer-type FAI), the proximal femur (Cam-type FAI), or commonly both (Fig. 7-1). Acetabular Deformity FAI caused by acetabular abnormalities is commonly referred to as pincer or rim impingement. This type of impingement results from overcoverage of the femoral head by the acetabulum and can have several etiologies (1,2,3). Focal overcoverage, or anterosuperior acetabular overhang (3), results from increased bone at the anterosuperior acetabular rim in the setting of an otherwise normal acetabulum. These patients will typically have a crossover sign on a well-positioned anteroposterior (AP) radiograph, but no posterior wall deficiency (i.e., a negative posterior wall sign) (3,4) (Fig. 7-2A). This is in contrast to patients with acetabular retroversion, in which the entire acetabulum is retroverted, causing anterior overcoverage and impingement along with posterior deficiency (3,5). Radiographically, these patients have a crossover sign in addition to a positive posterior wall sign and ischial spine sign (3,4,5) (Fig. 7-2B). Anterior overcoverage can also occur after a periacetabular osteotomy (PAO) performed for acetabular dysplasia (6). Global overcoverage indicates anterior, superior, and posterior acetabular overcoverage causing impingement circumferentially. This often occurs in the setting of coxa profunda and protrusio acetabuli, with medialization of the femoral head (2,3,4,7) (Fig. 7-2C). Each of these acetabular etiologies of FAI can be successfully treated with hip arthroscopy in properly indicated patients. It is critical that the impingement “fingerprint” (7) of each patient be carefully analyzed, as the presence/absence of femoral-sided deformities and the exact location of the impingement will often dictate whether arthroscopic treatment is appropriate.   P.72
	TABLE 7-1 Indications for Arthroscopic Treatment of Structural Hip Problems

Acetabular deformities

Focal anterosuperior overcoverage

Relative anterior overcoveragea Acetabular retroversion Postperiacetabular osteotomy

Global overcoverageb

Coxa profunda Protrusio acetabuli

Femoral deformities

Idiopathic Cam deformity

Developmental Cam deformity

Prior slipped capital femoral epiphysis Sequelae of Legg-Calvé-Perthes diseaseb

Posttraumatic Cam deformity

Femoral neck nonunion

Extra-articular Deformities

AIIS/subspine impingement

aCaution must be exercised as resection of too much bone in cases of relative anterior

overcoverage can result in global acetabular deficiency.

bThese diagnoses are commonly associated with global deformities that may be better suited for

treatment with surgical hip dislocation.

 

 

 

 

 

FIGURE 7-1 A: Schematic diagram of pincer-type FAI, with abnormal contact between the femoral headneck junction and the acetabular rim. Direct impingement anteriorly causes damage to the acetabular labrum, while leverage of the femoral head leads to a contrecoup lesion with damage to the posteroinferior femoral head and acetabular chondral surfaces. B: Schematic diagram of Cam-type FAI, with a nonspherical femoral head abutting against the acetabular rim during hip flexion. This causes damage to

the labrum and acetabular articular cartilage in the area of impingement. (From Ganz R, Rapvizi J, Beck M, et al.: Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res (417): 112-120, 2003.)

 

 

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FIGURE 7-2 Radiographs of conditions associated with pincer impingement. A: Focal anterior overcoverage—the outline of the acetabular rim (dashed line) creates a crossover sign (black arrow), while the center of the femoral head (X) is medial to the posterior wall. B: Acetabular retroversion—the outline of the acetabular rim (black dashed line) creates a crossover sign (black arrow), while the center of the femoral head (X) is lateral to the posterior wall and there is a prominent ischial spine sign (white dashed line and arrow). C: Coxa profunda—the medial acetabular wall (solid line) is medial to the ilioischial line (dotted line).

Femoral Deformity

FAI caused by femoral-sided deformities is commonly referred to as Cam impingement. This type of impingement occurs due to a nonspherical femoral head that cannot be accommodated by the acetabulum due to its increased radius (1,2,8). Radiographically, patients will typically have decreased femoral headneck offset and femoral head asphericity (4) (Fig. 7-3). The etiology of these femoral deformities remains unclear for most patients. For others, developmental (e.g., prior slipped capital femoral epiphysis [9] and Legg-Calvé-Perthes disease [10]) or posttraumatic (e.g., femoral neck fracture malunion [11,12]) causes can be identified. Regardless of the etiology, femoral deformities causing FAI anteriorly and laterally are amenable to treatment with arthroscopic decompression.

 

 

 

FIGURE 7-3 Radiograph of a hip with a large Cam deformity of the AL femoral headneck junction (arrow)

resulting in loss of femoral head-neck offset and asphericity of the femoral head.

 

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FIGURE 7-4 Three-dimensional reformatting of a left hip CT scan showing the AIIS (dashed line) with excess bone in the area distal to it (arrow), which can lead to subspine impingement.

Extra-articular Deformity

Bony abnormalities of the anterior inferior iliac spine (AIIS) can cause impingement against the distal aspect of the femoral neck (13) (Fig. 7-4). This type of impingement is commonly termed AIIS/subspine impingement and can be successfully treated with arthroscopic decompression (14).

 

 

 

CONTRAINDICATIONS (TABLE 7-2)

Hip arthroscopy in patients with acetabular dysplasia should be utilized with extreme caution. Numerous reports of iatrogenic instability and rapid progression of osteoarthritis after hip arthroscopy in this circumstance exist (15,16,17). However, arthroscopy can be a valuable tool in treatment of patients with labral pathology and femoral-sided deformities, even in the setting of mild acetabular dysplasia. Hip arthroscopy has also been utilized successfully to treat intra-articular pathology in patients undergoing concurrent PAO for more severe dysplasia (18).

FAI due to true acetabular retroversion may be a contraindication to arthroscopic treatment, as resection of the impinging anterolateral (AL) rim may lead to global acetabular deficiency because these patients are typically undercovered posteriorly. As in hip dysplasia, arthroscopy can be used to treat labral pathology and femoral-sided deformities in these patients. However, patients with isolated acetabular retroversion or severely retroverted sockets are usually better managed with an anteversion, or reverse, PAO (19,20). Arthroscopy may be used as an adjunct in these cases to address labral pathology.

Arthroscopic management of FAI in the setting of severe femoral or acetabular deformities may also be contraindicated. Limitations in arthroscopic techniques render treatment of posterior and medial deformities difficult or impossible. As a result, global deformities are typically best managed with open techniques, including surgical hip dislocation (19,21).

The presence of advanced degenerative changes is another contraindication to hip arthroscopy. Patients with predominantly arthritic-type pain (i.e., aching pain at rest), greater than 50% joint space narrowing, and bipolar grade 4 chondral lesions have been found to have poor outcomes after arthroscopy (7).

 

 

TABLE 7-2 Relative Contraindications to Isolated Arthroscopic Treatment of Structural Hip Problems

Acetabular dysplasia, moderate to severe Isolated or severe acetabular retroversion

Global acetabular overcoverage (e.g., protrusio acetabuli) Global femoral deformity (e.g., Perthes disease) Advanced degenerative changes

 

 

 

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PREOPERATIVE PREPARATION

Patient Assessment

Careful history and physical examination are crucial in identifying appropriate hip arthroscopy candidates.

Patients must have pain referable to the hip. Often, hip pain will be localized to the groin with a classic “C” sign, but may localize to the buttock, lateral hip, lower back, thigh, and even medial knee (22). Patients with intermittent pain during activities, especially sitting and other high hip flexion activities, are optimal candidates compared to those with constant aching pain (7). Limitation of hip internal rotation in flexion as well as exacerbation of pain with flexion, adduction, and internal rotation of the hip suggest anterior FAI that may be amenable to arthroscopic treatment. In select cases, we use image-guided intra-articular local anesthetic injections as a diagnostic tool to confirm pain localization to the hip joint itself prior to proceeding with surgery (23).

Radiographic Assessment

Routine radiographs include an AP pelvis as well as frog-leg and cross-table lateral views of the affected hip. These views allow thorough assessment of the anterior and lateral femoral head-neck junction to assess sphericity and the acetabulum to assess coverage, depth, and version. The AP pelvis radiograph must be carefully scrutinized to ensure proper pelvic rotation and tilt (4) as these parameters can significantly affect radiographic markers of acetabular coverage (24). If acetabular dysplasia (lateral center edge angle [LCEA] ≤ 25 degrees) is present on the AP pelvis radiograph, a false profile view is obtained to measure the anterior center edge angle and more precisely define the degree of dysplasia (4).

Magnetic resonance imaging (MRI) and computed tomography (CT) with three-dimensional (3D) reconstructions are routinely obtained on all patients with FAI who are being considered for surgery. MRI allows for precise evaluation of the soft tissues, including the acetabular labrum and the articular cartilage, while 3D CT images provide more precise localization of areas of femoral head asphericity and acetabular overcoverage. We have found the routine use of MR arthrogram to be unnecessary in practices where high-resolution 3-tesla scanners are available.

Preoperative Planning

Once a patient has been indicated for surgery, the planned resection is templated on the plain radiographs. For the acetabular resection, a 25-degree angle is positioned on the AP pelvis radiograph to replicate a 25-degrees LCEA (Fig. 7-5A). This identifies the limit of the acetabular resection, as resection medial to this point will result in acetabular undercoverage. Areas of femoral asphericity are identified

 

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on the AP and lateral radiographs, and planned resections, which will restore normal femoral headneck offset, are traced (Fig. 7-5B). Templating of the planned resections preoperatively allows for easy comparison to intraoperative fluoroscopy images to ensure adequate decompression is performed (25).

 

 

 

 

FIGURE 7-5 Preoperative radiographic templating of bony resection. A: A LCEA of 25 degrees is drawn on the AP radiograph. Any bone projecting lateral to this angle is safe to resect, as necessary, without causing iatrogenic dysplasia. B: The amount of bone necessary to restore femoral head sphericity and head-neck offset is drawn (dashed line) on the lateral radiograph.

 

TECHNIQUE

Anesthesia

Hip arthroscopy is performed under general anesthesia with muscle relaxation to facilitate hip joint distraction. We have had good success with preoperative fascia iliaca blockade to minimize intraoperative and postoperative opioid consumption (26). Controlled hypotensive anesthesia is utilized as well, with target systolic blood pressure

≤ 90 mm Hg, to minimize bleeding and facilitate visualization during the procedure.

 

Patient Positioning

Supine (27) and lateral (28) positioning for hip arthroscopy have been described. We routinely utilize supine positioning, as this is typically more familiar to operating room personnel and can be accomplished using a standard fracture table. Once general anesthesia has been administered, a well-padded radiolucent perineal post is inserted into the traction table and the patient is moved towards the foot of the bed until the post is in contact with the perineum. The post should be lateralized towards the operative hip so that it primarily contacts that medial upper thigh. This provides a fulcrum against which to distract the hip and theoretically reduces direct pressure on the pudendal nerve, possibly avoiding pudendal nerve injury (29,30,31). The contralateral arm can be left on an arm board to the patient's side while the ipsilateral arm is draped over the chest and secured. Next,

the patient's feet are secured in traction boots in a well-padded fashion using cast padding and Coban self-adhesive wrap. The operative foot must be particularly secure to prevent slippage during the application of traction. Once the feet are secured, the foot of the table can be removed. The non-operative leg is placed in approximately 45 degrees of abduction, while the operative leg is kept in neutral rotation, slight abduction, and full extension (Fig. 7-6).

 

 

 

 

FIGURE 7-6 Photograph of final patient positioning viewed from the side of the operative extremity. Note the position of the C-arm between the legs, and the position of the overhead monitors with arthroscopic and fluoroscopic images displayed opposite the surgeon. (From Spencer-Gardner L, Krych AJ, Levy BA, (section eds). Hip Arthroscopy in Monograph Series 52: Femoroacetabular Impingement. Rosemont, IL: American Academy of Orthopedic Surgeons, E-book, 2013.)

 

Fluoroscopy Positioning

Ensuring that adequate fluoroscopic images can be obtained prior to prepping and draping is crucial to the success of any hip arthroscopy, in order to carry out the preoperative plan. Slight traction is applied to both legs to stabilize the pelvis. The C-arm is brought in between the legs and the beam is centered over the operative hip. The preoperative AP pelvis radiograph is displayed on a separate operating room monitor while AP fluoroscopic images are obtained. The C-arm is then adjusted until the AP fluoroscopic image closely replicates the AP pelvis radiograph. The lateral acetabulum and medial teardrop are good landmarks to use to confirm similarity between images, and the lateral acetabulum will help

 

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identify the amount of crossover and overcoverage that should be resected. This step eliminates any discrepancies in radiographic acetabular coverage markers between the preoperative radiographs and the

fluoroscopy images. Next, the C-arm gantry is rotated to a near horizontal and then horizontal position, and the ability to obtain an adequate oblique lateral and cross-table lateral, respectively, is confirmed. Note that the greater trochanter may obscure the distal femoral neck on oblique and lateral images, which, if not remedied, may cause a failure to recognize and treat distal impinging Cam lesions.

Application of Traction

At least 8 to 10 mm of hip joint distraction must be obtained in order to introduce arthroscopic instruments into the hip joint without causing iatrogenic chondral and/or labral damage (32). This typically requires 25 to 50 pounds of traction (27). In-line traction is applied to the operative leg, and countertraction is applied to the nonoperative leg. Initial traction is applied with the operative hip slightly abducted, and subsequent adduction will assist with joint distraction, due to the fulcrum of the perineal post.

Portal Placement (Table 7-3)

Anatomic landmarks for portal placement are identified only after joint distraction is established to prevent migration of the skin relative to the underlying bony landmarks. The first landmarks to identify and mark are the anterior superior iliac spine (ASIS) and the tip of the greater trochanter. Two perpendicular lines are then drawn: one from the ASIS distally to the center of the patella and one from the tip of the trochanter anteriorly to the intersection with the first line (Fig. 7-7). Subsequent portal placement should be kept lateral to the ASIS-to-patella line to minimize risk of femoral nerve injury (33,34).

 

 

TABLE 7-3 Starting Points for Specific Hip Arthroscopy Portals (33) (Fig. 7-7)

Anterolateral portal—established in line with the anterior border of the greater trochanter 1 cm proximal to the horizontal line; a soft spot can often be felt here just anterior to the tensor fascia lata insertion onto the iliotibial band.

Posterolateral portal—established in line with the posterior border of the greater trochanter 1 cm proximal to the horizontal line.

Anterior portal—established just distal and lateral to the intersection of the vertical and horizontal lines. Mid portal—roughly localized by creating a distally directed equilateral triangle with the anterior portal and AL portal; exact location varies with patient body habitus and orientation as well as amount of acetabular version.

Proximal mid portal—roughly localized by creating a proximally directed equilateral triangle with the anterior portal and AL portal; exact location varies with patient body habitus and orientation.

Distal anterolateral accessory portal—established in line with the AL portal, 4-5 cm distal to it.

 

 

 

 

 

FIGURE 7-7 Intraoperative photograph of potential portal placement sites. To aid portal starting point identification, two perpendicular lines are drawn: one from the ASIS distal to the center of the patella (yellow dashed line) and one from the tip of the greater trochanter anteriorly to the intersection with the first line (white dotted line). X, middle of greater trochanter; darkened circle, anterior superior iliac spine; AP, anterior portal; MA, midanterior portal; DALA, distal anterolateral accessory portal; PMA, proximal midanterior portal; AL, anterolateral portal; PL, posterolateral portal. (From Spencer-Gardner L, Krych AJ, Levy BA (section eds). Hip Arthroscopy in Monograph Series 52: Femoroacetabular Impingement. Rosemont, IL: American Academy of Orthopedic Surgeons, E-book, 2013.)

 

 

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The vast majority of hip arthroscopy for FAI in our practice is performed using two portals— midanterior (MA) and AL. A spinal needle through the posterolateral (PL) portal is used for outflow purposes. Under fluoroscopic guidance, a 6-inch spinal needle is advanced from the AL portal starting point towards the hip joint at an insertion angle of approximately 15 degrees towards the floor and 15 degrees cephalad. As the spinal needle is advanced into the joint, care must be taken to avoid piercing the labrum and avoid damaging the femoral articular cartilage. To aid in this, the needle is aimed just proximal to the femoral head (as far from the labrum as possible) with the bevel towards the head (to minimize risk of iatrogenic cartilage injury) (35).

Once the spinal needle is in the hip joint, the stylet is removed and air is injected into the joint to create an air arthrogram. A second AP fluoroscopic image is obtained. If the spinal needle has migrated proximally, it may be within the labrum and should be removed and positioned more distally. If the spinal needle remains stationary after the air arthrogram, it is safe to proceed with instrumentation of the hip joint. A Nitinol wire is threaded through the spinal needle until resistance is met. Position is checked on fluoroscopy, and the guide wire should be seen abutting the medial acetabular wall (Fig. 7-8). If the guide wire does not advance all the way to the medial wall, it may be too anterior or posterior and the spinal needle should be repositioned accordingly. If needed, a lateral fluoroscopic image can help determine anteroposterior placement of the spinal needle.

After confirming proper intra-articular position, a skin incision is made over the guide wire. A 4-mm dilator is passed over the guide wire followed by the 4.5-mm arthroscopy trocar. This step should be performed with a twisting motion and slow, controlled pressure to minimize the risk of plunging and damaging the articular cartilage after the hip joint capsule is pierced. The 70-degree arthroscope is introduced into the hip joint dry with the inflow turned off.

Under direct visualization, the PL outflow portal is now established. Looking posteriorly, the “V” between the posterior labrum and the femoral head is identified (Fig. 7-9). The 6-inch spinal needle is advanced from the PL portal starting point to the center of this “V.” The typical trajectory is 5 degrees towards the ceiling and 5 degrees cephalad, with slight convergence to the camera in the AL portal.

Next, the MA portal is established under direct visualization. Looking anteriorly, the “V” between the anterior labrum and the femoral head is identified (Fig. 7-10). The 6-inch spinal needle is advanced from the MA portal starting point to the apex of this “V,” with a typical trajectory of 25 degrees towards the floor and 35 degrees cephalad. Once the spinal needle is properly positioned, the stylet is removed and a Nitinol guide wire is inserted. A skin incision is made, and the 4-mm dilator is threaded over the wire, followed by a 6-mm dilator.

 

 

 

 

FIGURE 7-8 Intraoperative fluoroscopic image showing a Nitinol wire passed through the spinal needle in the AL

portal abuts the medial acetabular wall (*), indicating proper portal placement. Note the positioning of the spinal needle, near the femoral head with the bevel directed towards the head (#).

 

 

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FIGURE 7-9 Arthroscopic image looking posteriorly from the AL portal visualizing the “V” between the femoral head (FH) and the posterior labrum (PL). The spinal needle has been introduced through the PL portal.

 

 

 

 

 

FIGURE 7-10 Arthroscopic image looking anteriorly from the AL portal visualizing the “V” between the femoral head (FH) and the anterior labrum (PL). The spinal needle has been introduced through the MA portal.

 

Capsulotomy

A curved arthroscopic knife is inserted through the 6-mm dilator in the MA portal, and the dilator is removed from the joint. At this point, the inflow is turned on and the presence of outflow is confirmed. The capsulotomy is extended anteriorly from the MA portal first. Then, an arthroscopic cannula is placed in the MA portal, and two switching sticks are used to switch the camera to the MA portal and the arthroscopic knife to the AL portal. The

capsulotomy is then extended posteriorly from the AL portal to the PL outflow needle. Portals are once again switched, and an interportal capsulotomy is made by extending the anterior capsulotomy posteriorly from the MA portal to the

 

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AL portal. During capsulotomy, care is taken to avoid damage to the labrum and femoral articular cartilage.

Additionally, the capsulotomy is made as far distal from the labrum as visualization will allow, thereby leaving a substantial cuff of capsular tissue for later repair as well as allowing for better visualization of the peripheral compartment. We have found this technique to provide adequate visualization and maneuverability within the central and peripheral compartments in the majority of cases without the need for capsulectomy or T-capsulotomy (36).

Central Compartment

Evaluation of the central compartment begins with a thorough diagnostic arthroscopy (37) to include the ligamentum teres; anterior, lateral, and posterior labrum; anterior, lateral, and posterior acetabular articular cartilage both peripherally and centrally; and the femoral head articular cartilage. Once all pathology of the central compartment has been identified, attention is turned to treatment of the structural deformities.

Articular Cartilage Assessment and Treatment Acetabular articular cartilage disease is nearly universal in patients undergoing hip arthroscopy for FAI, and femoral articular cartilage disease is present in up to 23% of patients (38). The pattern of chondral injury will vary with the pattern of FAI. Cam-type impingement tends to cause delamination (Fig. 7-11A) and detachment of the anterosuperior acetabular cartilage due to shear forces (39,40,41). Pincer-type impingement tends to cause damage to the posteroinferior femoral head and acetabular articular cartilage due to the contrecoup phenomenon (41) (Fig. 7-11B). Most often, FAI is mixed type (39), in which case mixed patterns of chondral injury can be seen.

Chondral restoration techniques, such as autologous chondrocyte implantation, mosaicplasty, and osteochondral allograft transplantation, have been described, but require surgical hip dislocation to perform (42). Arthroscopic treatment options for articular cartilage lesions in the hip include debridement, abrasion chondroplasty, microfracture, and reattachment with either sutures or adhesives such as fibrin glue (42,43,44,45). Long-term outcomes for these treatment options are unknown (43). In our practice, contained full-thickness chondral lesions

of small or medium size (≤2 to 4 cm2) (45) in young patients are treated with microfracture. Many of these lesions will extend to the anterosuperior border of the acetabular articular surface and, thus, are technically uncontained. However, once the labrum has been repaired, a shoulder is recreated to contain the lesion and

 

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microfracture can be performed satisfactorily. Chondral lesions that are partial thickness and those that are large (greater than 2 to 4 cm2) and/or uncontained are treated with simple debridement.

 

 

 

FIGURE 7-11 Arthroscopic images of chondral pathology in FAI. A: Delamination of the AL acetabular articular cartilage resulting from Cam-type FAI. B: Degeneration of the posterior acetabular articular cartilage (*) resulting from the contrecoup phenomenon of pincer-type FAI. AL, anterior labrum; PL, posterior labrum; AC, acetabular cartilage; FH, femoral head.

 

Labral Assessment and Management Prior to resecting any bony deformity on the acetabulum, the acetabular labrum must be addressed. Nearly all patients undergoing hip arthroscopy for FAI have labral pathology. As is the case with the articular cartilage, different patterns of hip impingement lead to different patterns of labral pathology. With pincer-type impingement, the labrum is commonly torn at the chondrolabral junction (Fig. 7-12A) or within the substance of the labrum (Fig. 7-12B), whereas Cam-type impingement leads to chondrolabral delamination with preservation of the chondrolabral junction (Fig. 7-12C) (1,41). Again, most FAI is mixed type (39), so mixed patterns are common.

In order to treat labral pathology and remove bony pincer deformities, the labrum must either be excised or preserved and moved out of the way to facilitate pincer takedown prior to labral refixation. Comparative studies have demonstrated superior outcomes after labral preservation and refixation compared to debridement alone (46,47,48,49,50). As such, the labrum should be preserved and repaired whenever possible. Occasionally, the quality or quantity of the labral tissue makes suture repair unfeasible. In these cases, labral debridement is performed. This is performed by separating the labrum from the capsule and chondrolabral junction using the arthroscopic shaver and radiofrequency (RF) probe. Then, an arthroscopic shaver is used to resect the labrum. Care is taken to limit the debridement to the tissue that is either torn or must be removed to fully expose the pincer lesion. The remaining normal-appearing labrum is tapered at the junction of the resected tissue.

When labral preservation is possible, the surgeon must decide how to manage the labrum in order to gain exposure to the underlying pincer lesion while avoiding iatrogenic damage to the labral tissue. Techniques for pincer resection with (51,52,53) and without (52,54) labral takedown at the chondrolabral

 

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junction have been described. The rationale behind chondrolabral junction preservation includes preservation of labral blood supply and maximizing healing potential (55,56). However, when pincer resection of greater than 3 mm in width is planned, labral takedown is performed (52) as preservation of the chondrolabral junction will result in undesirable redundancy of the articular cartilage.

 

 

 

FIGURE 7-12 Arthroscopic images of labral pathology in FAI. A: Labral detachment at the chondrolabral junction (*), more commonly seen in the setting of pincer-type impingement. B: Intrasubstance labral tearing, more commonly seen in pincer-type FAI. C: Delamination of the chondrolabral complex with preservation of the chondrolabral junction (*) and a “carpet sign” (arrow) of the peripheral cartilage, more commonly seen in Cam-type FAI. AL, anterior labrum; AC, acetabular cartilage; FH, femoral head.

 

 

 

 

FIGURE 7-13 Arthroscopic image after labral takedown. The labrum (L) is detached at the chondrolabral junction to expose the underlying articular cartilage (AC) and acetabular rim (AR) and facilitate bony rim resection.

 

In cases where the chondrolabral junction is intact and minimal (≤3 mm) bony pincer resection is planned, labral takedown is not performed. After separating the capsule and labrum using the shaver and RF ablator, the capsule is elevated off of the underlying acetabular rim. The shaver and RF probe must be oriented to protect the labrum from iatrogenic damage during this step. After complete exposure of the pincer deformity, bony resection is performed. If the labrum is noted to be unstable after the bony resection, refixation is performed.

In cases where the chondrolabral junction is torn or greater than 3 mm bony pincer resection is planned, labral takedown is performed. Elevation of the capsule from the underlying bone is performed as described above. The labrum is then detached at the chondrolabral junction using either an arthroscopic elevator or RF probe and working in an anteroposterior direction. Only labrum that is torn or overlies the pincer deformity should be detached. Iatrogenic damage to the labrum and articular cartilage is possible during this step, so it must be executed with care. Once the labrum has been adequately mobilized to allow complete exposure of the pincer deformity (Fig. 7-13), bony resection is performed. This is followed by labral refixation.

Pincer Resection (57) Once satisfactory exposure of the pincer lesion has been obtained, pincer resection is carried out under fluoroscopic guidance (25). A 5.5-mm burr is used for bony resection. The burr is first introduced through the MA portal and positioned at a location on the anterior acetabular rim corresponding with the crossover sign on the AP radiograph. Burr positioning is confirmed with fluoroscopy (Fig. 7-14A). While obtaining frequent fluoroscopic images, the anterior portion of the pincer lesion is removed with the burr. Once this step is completed, the crossover sign will have disappeared on the fluoroscopic image (Fig. 7-14B). This can be confirmed when the burr, positioned on the resected bed, lies medial to the fluoroscopic projection of the posterior wall. The portals are then switched so the arthroscope is in the MA portal and the burr is in the AL portal. Attention is turned to resecting the superolateral portion of the pincer lesion. Frequent fluoroscopic images are obtained and compared to the templated resection on the preoperative AP radiograph to insure against overresection by maintaining an LCEA greater than 25 degrees. During pincer resection, care is taken to avoid iatrogenic labral damage from the burr. The junction between the anterior and superolateral portions of the resection should be smooth as well (Fig. 7-15).

 

 

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FIGURE 7-14 Fluoroscopic images of the acetabular rim (arrow) before (A) and after (B) pincer resection.

 

 

 

 

FIGURE 7-15 Arthroscopic images before (A) and after (B) pincer resection. L, labrum; AC, acetabular cartilage; AR, acetabular rim.

 

Labral Refixation (58) After complete resection of the pincer deformity has been confirmed, labral refixation is performed. Knotless bioabsorbable suture anchors are utilized for refixation. Anchors are typically spaced 6 to 8 mm apart (52), so the number of anchors utilized varies based on the length of the labrum that must be reattached, but 4 to 5 anchors are most common in our practice. Anteromedial suture anchors (1:00 to 3:00) are placed via the MA portal, while superolateral suture anchors (10:00 to 1:00) are placed via the AL portal. A distal AL accessory portal can also be used for anchor placement, depending on surgeon preference and portal trajectory. The pilot holes for all

 

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planned anchors are drilled prior to placing any anchors to improve efficiency. Care must be taken to avoid intra-articular penetration of the pilot holes, and proper position should be confirmed by direct visualization arthroscopically and with fluoroscopic images.

Once pilot holes have been drilled, labral sutures are passed one at a time, from anterior to posterior, using the labral base refixation (LBR) technique (52), and the labrum is reattached to the bed of the resected acetabular rim with the knotless anchors. The LBR technique utilizes a suture passer to pass a stiff, nonabsorbable suture through the labral base, exiting the labrum on the capsular surface (Fig. 7-16). This suture is then retrieved, and the knotless anchor is used to reattach that segment of the labrum. This is repeated once for each suture anchor to obtain stable labral fixation (Fig. 7-17). This labral repair technique preserves the triangular cross-sectional anatomy of the labrum, which may preserve its biomechanical properties (52).

 

 

 

FIGURE 7-16 LBR technique diagram demonstrating restoration of the labrum's native triangular cross-sectional shape after refixation. L, labrum; A, acetabulum; FH, femoral head. (From Fry R, Domb B: Labral base refixation in the hip: rationale and technique for an anatomic approach to labral repair. Arthroscopy 26(9): S81-S89, 2010.)

 

 

 

 

FIGURE 7-17 Arthroscopic image after labral repair using the LBR technique. L, labrum; AC, acetabular cartilage; FH, femoral head.

 

 

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FIGURE 7-18 Arthroscopic image after the release of traction showing the reconstitution of the labral seal

(arrow) after labral takedown and subsequent refixation. AR, acetabular rim; L, labrum; FH, femoral head.

 

Most of the time, labral refixation can be accomplished using this single-pass LBR technique, but a simple looped suture technique may be utilized if the residual labral tissue is too small (less than 3 mm) to accommodate a labral base stitch (52). Likewise, if the residual labral tissue is greater than 5 mm, a vertical mattress LBR technique can be employed, which involves passing the suture through the labral base twice prior to suture anchor fixation (52).

After satisfactory labral fixation has been obtained, traction is released. The femoral head is visualized as it reduces into the acetabulum so the restoration of the labral suction seal can be confirmed (Fig. 7-18). If there is excessive eversion of the repaired labrum and the seal has not been re-established, the surgeon must consider revising or adding additional labral fixation to correct this, as the seal is imperative for restoration of normal labral function.

Peripheral Compartment

Once the pincer deformity and labral and articular cartilage pathology have been addressed, attention is turned to the peripheral compartment and treatment of the Cam deformity. To facilitate peripheral compartment arthroscopy, traction is released and the hip is flexed to approximately 40 degrees and placed in slight external rotation and abduction. This position takes tension off of the capsule and allows easier access to the peripheral compartment.

Visualization In most cases, an interportal capsulotomy is adequate for visualization of the peripheral compartment. However, if the entire femoral-sided deformity cannot be adequately visualized, several options exist. One is to establish a third portal (either a distal or proximal AL accessory portal) and introduce a switching stick to be used as a capsular retractor. Another option is to perform a limited capsulectomy with the arthroscopic shaver. A third is conversion of the interportal capsulotomy to a T-capsulotomy, as described by Bedi et al. (36). After blunt dissection of the soft tissues off of the superficial surface of the joint capsule, the vertical limb of the

T-capsulotomy is carried distally parallel to the femoral neck. Ideally, this limb should follow a fat plane separating the medial and lateral limbs of the iliofemoral ligament. If this is accomplished, the iliocapsularis will pull the medial limb medially while the gluteus minimus will pull the lateral limb laterally, giving excellent

visualization of the femoral head-neck junction. To minimize risk of injury to terminal branch of the lateral femoral circumflex artery, caution should be exercised if the vertical limb is carried distal to the zona orbicularis.

 

 

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FIGURE 7-19 Arthroscopic image showing the lateral synovial fold (arrow), the site of the terminal branches of the medial femoral circumflex artery. C, hip joint capsule; FN, femoral neck.

 

 

 

TABLE 7-4 General Principles to Follow While Performing Cam Resection

Tailoring the amount and location of the resection for each individual patient as not all Cam lesions are the same

Restoration of normal femoral head-neck offset with a goal alpha angle of ≤55 degrees

Gradual transitioning of the resection from the normal femoral head articular cartilage to the femoral neck to restore sphericity and avoid “sharp” edges that may cause catching as the head moves in and out of the socket

Frequent fluoroscopic imaging to confirm location and depth of the resection

Limiting the resection to 30% of the diameter of the femoral neck to minimize risk of femoral neck fracture (60)

Occasional dynamic assessment of hip impingement to check adequacy of the resection

 

After adequate visualization of the peripheral compartment has been obtained, the safe zone for Cam resection must be identified. The medial synovial fold represents the medial limit for Cam resection, and lateral synovial fold (Fig. 7-19), which is the site of the superior retinacular vessels, represents the lateral limit for Cam resection

(59) (Table 7-4).

Cam Resection (61) Understanding the relationship between arthroscopic anatomy and fluoroscopic images is critical to successfully performing arthroscopic Cam resection. With the hip in neutral rotation, far anterior and anteromedial portions of the Cam lesion (4:00 to 6:00) will be seen best on the cross-table lateral radiograph. AL portions of the Cam lesions (2:00 to 4:00) will be seen on the frog-leg lateral radiograph. Finally, superolateral portions of the Cam lesions (12:00 to 2:00) will be best seen on the AP radiograph. It is also important to

recognize that flexion and external rotation will bring more anterior portions of the Cam lesion into the arthroscopic field of view whereas extension and internal rotation will bring more lateral parts of the lesion into view. With the hip in the flexed, abducted, and externally rotated position, the medial extent of the Cam lesion is visualized and can be resected with the 5.5-mm round burr. Next, the hip is internally rotated slightly to bring the anterior portion of the lesion into view. Rotating the fluoroscopy arm into a near-lateral position (20 to 30 degrees shy) at this point will produce a cross-table lateral view of the femoral head-neck junction and allow careful monitoring of the anterior bony resection (Fig. 7-20).

Continuing to work with the arthroscope in the AL portal and using the MA portal for instrumentation, the Cam lesion is resected in a systematic fashion, working from medial to lateral. The 5.5-mm burr is used, alternating between forward and reverse settings in areas where aggressive and delicate resection is required, respectively. As the resection proceeds, the hip can be extended and/or internally rotated to bring more lateral portions of the lesion into view. The fluoroscopy arm can be rotated incrementally towards the AP position to profile the AL and lateral portions of the lesion, as well.

Resection of the far lateral portion of the lesion is carried out by extending and internally rotating the hip to expose this part of the Cam lesion. AP positioning of the fluoroscopy arm will profile the

 

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lateral aspect of the lesion and allow monitoring of the bony resection (Fig. 7-21). Instruments can be kept in the same portals, but sometimes, resection is more easily accomplished by switching and working through the AL portal. Extreme caution must be taken working posterolaterally from this position, as this will bring the resection very close to the lateral synovial fold and retinacular vessels.

 

 

 

 

FIGURE 7-20 Intraoperative fluoroscopic images showing the anterior femoral head-neck junction before (A) and after (B) Cam resection.

 

 

After completion of the resection, a thorough survey of the resected bed is taken. Any sharp edges are smoothed. Final fluoroscopic images of the lateral, AL, and anterior femoral head-neck junction

 

are obtained to confirm an adequate resection by assessing femoral head sphericity and head-neck offset.

 

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Dynamic examination of the hip with flexion, adduction, and internal rotation should be performed to ensure the absence of any persistent FAI.

 

 

 

FIGURE 7-21 Intraoperative fluoroscopic images showing the lateral femoral head-neck junction before (A) and after (B) Cam resection.

 

Capsular Repair (62) After Cam resection is complete, the decision of whether or not to repair the capsulotomy must be made. Biomechanical studies (63,64,65) and clinical case reports (66,67,68) have implicated that an unrepaired capsulotomy may contribute to hip instability postoperatively. Some authors have suggested that capsular repair be performed in every hip arthroscopy (69). However, capsular repair does increase operative time and cost and may limit hip external rotation postoperatively due to overtightening. We perform capsular repair in patients with generalized or hip-specific laxity or hip dysplasia, as these patients probably have the highest risk of postoperative instability.

Our technique for capsular closure is as follows (Fig. 7-22). With the arthroscope in the AL portal, the hip is flexed 30 to 40 degrees and internally rotated slightly to relax the capsule. An arthroscopic

 

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cannula is placed into the MA portal and left in place until capsular closure is complete. The shaver and RF

probe are used to clear soft tissues, including the iliocapsularis muscle, from the superficial surface of the joint capsule. Typically, two to four simple stitches are placed, depending on the size of the capsulotomy. Sutures are placed anteromedially first, progressing laterally. For each stitch, a #2 braided absorbable suture is passed first through the proximal limb. This can be accomplished by introducing either a 6-inch spinal needle loaded with a wire loop for shuttling, or any of a number of commercially available suture passers, percutaneously just proximal and medial to the MA portal. Next, a curved, penetrating suture passer/retriever is introduced through the cannula in the MA portal and is used to pierce the distal limb of the capsule and retrieve the wire loop. Both limbs are brought out the cannula, and a knot pusher is used to tie an arthroscopic knot, securing the two limbs of the capsule together.

 

 

 

FIGURE 7-22 Arthroscopic images of capsular repair. A: Exposure of the two limbs (proximal and distal) of the interportal capsulotomy. B: A suture is passed first through the proximal limb. C: The suture is then retrieved through the distal limb. D: Repaired capsule after placing and tying two simple stitches. *, distal limb of capsulotomy; †, proximal limb of capsulotomy.

 

Closure and Dressing

Wounds are closed with 3-0 nylon modified horizontal mattress sutures, and a soft, absorbent dressing is placed. This is followed by a compressive hip wrap and ice pack to minimize postoperative swelling.

POSTOPERATIVE MANAGEMENT

We have previously described a five-phase postoperative rehabilitation program (70) that is used in all patients. The first phase (weeks 0 to 4) focuses on reducing pain and inflammation in the hip joint and protecting the labral and/or capsular repair. Hip hyperextension, excessive external rotation, and rotation in flexion are avoided to protect the labral repair. Toe-touch weight bearing is prescribed for 4 weeks following a labral repair and for 2 weeks following labral debridement. A continuous passive motion machine is utilized after cases in which microfracture has been performed.

The second rehabilitation phase (weeks 4 to 8) focuses on advancing weight bearing and range of motion and incorporates core training, proprioception, and nonimpact aerobic training. The third phase (weeks 8 to 12) advances strengthening and conditioning in preparation for upcoming sport-specific drills that will be encountered in phase four (weeks 12 to 16). Satisfactory performance on movement screening and Y-balance testing (71) as well as hip muscle strength of at least 90% of the contralateral side are required prior to progression to phase four. Phase five (weeks 16 to return to full activity) is initiated once single-leg functional power tests are at least 90% of the contralateral side. This phase focuses on increasing strength and endurance and developing a hip maintenance exercise program once the patient has been cleared for return to full activity.

At 1-year follow-up, patients who participated in this rehabilitation program after hip arthroscopy had a mean modified Harris hip score of 80.1 ± 19.9. 79% of patients rated their level of function, as related to the hip, as normal or nearly normal.

 

COMPLICATIONS

Complications appear to be relatively uncommon after hip arthroscopy. Several recent, large systematic reviews have reported the major complication rate to be 0.3% to 0.6% (30,31) and the minor complication rate to be 4.0% to 7.5% (30,31). By far, the most common minor complication is iatrogenic chondral or labral injury (30), which can often be avoided with careful surgical technique. Several of the more common or severe complications are discussed below.

Underresection

Underresection on either the femoral or acetabular sides can lead to persistent FAI symptoms postoperatively as well as continued damage to the labrum and articular cartilage. Revision osteochon-droplasty for residual FAI is a common reason for reoperation after hip arthroscopy (30,72). The best way to avoid this underresection is to have a clear preoperative plan for the amount of bony resection necessary and to then ensure adequate visualization (fluoroscopically and arthroscopically) of the pincer and Cam lesions.

Overresection

Overresection can occur on either the femoral or acetabular sides. Femoral-sided overresection can lead to femoral neck fracture in the postoperative period (30,73). Resection should be limited to 30% of the width of the femoral neck to minimize risk of this complication (60). Overresection on the acetabular side can lead to iatrogenic acetabular dysplasia, with resultant hip instability (30,68), edge

 

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loading of the lateral hip joint, and rapid progression of osteoarthritis. As is the case with underresection, the best way to avoid overresection is careful preoperative planning and good intraoperative visualization. It should be noted that not all cases of postoperative instability are associated with over-resection. Hip dislocation after arthroscopy has been reported in patients with capsular laxity (66,67).

Nerve Injury

The most common complication after hip arthroscopy, other than iatrogenic chondral and labral damage, is neurologic injury (30). An overall rate of 1.4% has been published in a large, recent meta-analysis (30).

These injuries are commonly related to traction, but can be related to portal placement as well. Pudendal nerve injury is most common, while lateral femoral cutaneous, sciatic, common peroneal, and femoral nerve injuries have also been reported. Fortunately, 99% of postoperative neurologic deficits are temporary (30). Limiting the duration and amount of traction utilized can help limit the risk of traction-related neurologic injury.

Fluid Extravasation/Abdominal Compartment Syndrome

Extra-articular fluid extravasation is a rare, but potentially fatal complication of hip arthroscopy. Intraabdominal, retroperitoneal, and intrathoracic extravasation has been reported (30,31,74,75,76,77,78,79) along with resultant abdominal compartment syndrome (78,80) and even cardiac arrest (77,78). For this reason, we continually monitor abdominal swelling and ease of ventilation throughout the case. Fluid extravasation has been associated with longer operative time (75), higher pump pressures (76), and iliopsoas release (75). Extra care must be taken during cases in which these are necessary. If iliopsoas release is indicated, it should be performed at the end of the procedure to minimize extravasation.

Treatment of abdominal compartment syndrome can vary widely from observation to emergent laparotomy to decompress the retroperitoneal space (74).

Heterotopic Ossification

Clinically significant heterotopic ossification (Fig. 7-23) has been reported after less than 1% of hip arthroscopies (30), but can be a cause of significant disability and require reoperation for excision. To limit the risk of developing heterotopic ossification, adequate outflow should be maintained throughout the case, allowing thorough lavage of the resected bone particles out of the joint. Additionally, we prescribe a short course of indomethacin postoperatively in patients who do not have a medical contraindication.

 

 

 

FIGURE 7-23 Three-dimensional reformatting of a CT scan showing heterotopic ossification (white arrows)

after hip arthroscopy.

 

 

 

Venous Thromboembolism and Other Complications

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Other rare complications that have been reported after hip arthroscopy include perineal skin damage (30), pulmonary embolism (81), deep venous thrombosis (82), femoral head avascular necrosis (83,84), infection (30,31), and vascular injury (85). Venous thromboembolism (VTE) rates after hip arthroscopy have been reported to be 0% to 4% (86,87). We recommend using 325 mg aspirin twice daily for 4 weeks after hip arthroscopy for VTE prophylaxis. If the patient has a personal history of VTE, we obtain a consultation from our Thrombophilia Clinic for prophylaxis recommendations.

 

 

 

CLINICAL OUTCOMES

The preponderance of the evidence available suggests that hip arthroscopy is very successful in the treatment of FAI and labral tears. Most studies are limited by short-term follow-up, but a few long-term outcome studies have been published (88,89). A number of systematic reviews summarize the results of the short-term studies. Ng et al. reviewed 23 studies, all of which demonstrated improvements in patient symptoms after arthroscopic or open surgery for FAI (90). Stevens et al. found that 10 of the 12 studies they reviewed reported successful outcomes in ≥75% of patients with FAI treated with hip arthroscopy (91). They subsequently gave hip arthroscopy a Grade B recommendation (fair evidence in support of use) for the treatment of FAI. Patient satisfaction has been reported to be 67% to 100% after hip arthroscopy for FAI and labral tears (92,93), and Bedi et al. found that 93% of athletes were able to return to sport after treatment (92).

Prospective evaluations have shown significant improvements in clinical outcomes after hip arthroscopy for FAI for the first 6 to 12 months postoperatively (88,94). Byrd et al. reported stable results at 2 years postoperatively, but found slight deterioration of outcomes at 5 and 10 years after surgery (88). At long-term follow-up (greater than 10 years), two studies found that mean modified Harris hip score was improved 25 points over preoperative values (88,89). Results of revision hip arthroscopy appear to be more modest, with a recent, prospective study demonstrating only a 56% rate of successful outcomes at 3 years postoperatively (95).

Recent systematic reviews comparing open and arthroscopic treatment of FAI have suggested similar outcomes after both approaches (92,96), but treatment with arthroscopy was noted to have fewer complications and faster rehabilitation (96). Domb et al. performed a recent prospective comparative study of surgical hip dislocation and hip arthroscopy for treatment of FAI and found greater improvement in clinical outcomes in the arthroscopy group (97).

An intraoperative finding of Outerbridge Grade III/IV chondral damage is an independent predictor of worse outcomes after hip arthroscopy (89,90), as is radiographic osteoarthritis greater than Tönnis Grade I (90), age greater than 40 (88,89), and presence of symptoms for greater than 18 months (88). In the short term, conversion to THA has been noted in 0% to 9% of patients after arthroscopic treatment of FAI (93). Longterm (greater than 10 years follow-up) rates of conversion to THA have been reported to be 28% to 37% (88,89). Femoral head chondral damage is a stronger predictor of eventual conversion to THA than acetabular damage (89).

In all, the evidence suggests that hip arthroscopy is effective in the treatment of FAI and may be superior to open surgical approaches in terms of outcomes, complications, and recovery time. Further studies are needed to elucidate long-term outcomes of arthroscopic treatment of FAI and the benefits of arthroscopic versus open surgery.

 

PEARLS AND PITFALLS

Pearls

The crossover sign, posterior wall sign, coxa profunda, and protrusio acetabuli are signs of acetabular abnormalities found on the AP pelvis radiograph that are associated with FAI.

CT scan with 3D reconstructions, as well as femoral and acetabular version measurements, is a useful preoperative tool to assess whether bony deformity is most appropriately treated with an arthroscopic or an open approach.

Guided intra-articular injection of a local anesthetic is helpful in confirming that pain is localized to the hip joint in patients without classic symptoms of FAI. This can be performed at the time of MR arthrogram.

Prior to making incision, ensure that the AP fluoroscopy view closely matches the AP pelvis radiograph, thus allowing accurate monitoring of the amount of pincer resection and comparison with the preoperative templated resection.

 

 

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The vast majority of hips with FAI have mixed-type impingement and will need resection on both the acetabular and femoral sides for complete treatment.

The DALA portal can be useful for anchor placement to avoid subchondral penetration and also for acetabular chondroplasty and microfracture, as it provides a more direct angle to the chondral surface.

Switch to an AL working portal for pincer resection, labral repair, and anchor placement on the lateral and posterior acetabular rim.

Switching the burr rotation between forward and reverse allows for control of the aggressiveness of resection, depending on the consistency of the bone being resected.

Pitfalls

Outcomes of hip arthroscopy are worse in patients with Tönnis Grade 2+ osteoarthritis, age greater than 40, Outerbridge Grade III/IV cartilage injury, femoral head chondral damage, and symptoms present greater than 18 months.

Hip arthroscopy in the very obese patient may be difficult or impossible due to limitations of the length of the arthroscopic instruments.

Iatrogenic chondral and labral injuries are the most common complication of hip arthroscopy. Special care must be taken when entering the joint blindly to avoid this.

Traction-related injuries are the next most common complication of hip arthroscopy. Bony prominences must be well padded, and traction time and force should be limited to only what is necessary to complete the operation.

Resection of pincer lesions in patients with borderline dysplasia can exacerbate the dysplasia, leading to lateral subluxation, edge loading, and rapid progression of osteoarthritis.

The greater trochanter can obscure the distal femoral neck on oblique and lateral radiographs and fluoroscopic images, which may cause a failure to recognize distal impinging Cam lesions.

Reports of iatrogenic instability after hip arthroscopy do exist, so careful capsular management and consideration of repair/plication is warranted, especially in hips with dysplasia or hyperlaxity.

 

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