CHAPTER 12 Complex Therapeutic Hip Arthroscopy With the Use of a Femoral Distractor

Introduction

Hip pain in young adults is often characterized by nonspecific symptoms, normal imaging studies, and vague findings from the history and physical examination. As such, identifying the source and mechanism of the pain can be difficult. At the same time, treatment needs to be specific, because its effects will be experienced longer in this population. Emphasis will be placed on a newly established frequent cause of hip pain in the young adult called femoroacetabular impingement, which is a subtle form of early degenerative hip disease. A thorough arthroscopic correction of this pathology will be presented. The technique treats the acetabular component as well as the head component. This also includes labral suturing and cartilage transplantation, when necessary.

However, for such complex arthroscopic reconstructive surgery, longer traction times are necessary. It has been reported that traction times of more than 90 to 120 minutes on a traction table can provoke severe neurologic and perineal skin lesions in up to 15% of cases. The most frequent neurologic lesions reported are pudendal nerve lesions that result in clinical impotence as a result of the compression of the nerve on the perineal post of a traction table. Sciatic and femoral nerves are also at risk because of the overstretching that occurs during longer periods of time. Because these reconstructive procedures are time consuming, have a steep learning curve, and, above all, can provoke fearful complications, we have used invasive hip distraction (DR hip distractor, DR Medical, Solothurn, Switzerland) for these indications (Figure 12-1, A). Thus, by avoiding the need for traction against a perineal post with a traction table, we have not encountered the previously mentioned complications that occur with the use of the invasive hip distraction technique. The hip distractor allows the surgeon to perform these time-consuming surgical steps without the pressure of time to attain the same degree of perfection as occurs with open surgery. The results obtained are therefore identical to those of the open surgical technique. This is also a wonderful teaching tool, because beginners can also perform these more complex procedures without worrying about distraction time and the related complications.

Figure 12–1 A, Posterior view of right hip with the invasive hip distractor installed. Note the anterior-to-posterior precision screw mechanism (left), which allows for an increase in the anterior-to-posterior traction vector, thus opening the anterior joint space. The proximal-to-distal traction is controlled by the distal (right) precision screw mechanism. B, The proximal-to-distal controlled traction mechanism.

Basic science

Sufficient hip distraction involves traction forces of about 250 N to 500 N. After the suction seal is broken, the force needed diminishes significantly. However, on a traction table, much of the traction force is lost by uselessly distracting the knee (about 5 mm) and ankle joints (another 5 mm). After the invasive hip distractor has been installed, it produces a traction force of 500 N exclusively on the hip joint; this force is calculated in the elasticity of the dedicated Schanz screws. After this traction force is attained, the dedicated Schanz screws will be seen on the image intensifier to start bending (Figure 12-2, A through D).

Figure 12–2 A, Image intensifier view. Two distal Schanz pins in place at the level of the lesser trochanter. B, Two proximal Schanz screws 1 cm above the acetabular sourcil. C, Lower limb in neutral position with same view as that seen in part B but with traction applied. Note that 12 mm of joint space distraction is already visible in this young and muscular patient. The proximal Schanz screws have started to bend, thus signaling a sufficient 500 N of distraction force. D, Lower limb in 30 degrees of abduction. Note 18 mm of distraction (i.e., three times the diameter of the 6-mm Schanz screws). E, Same view as that seen in part D but after cam (i.e., pistol grip head) component correction with a burr.

In addition, on a traction table, the femoral head has a tendency to slide anteriorly and to reduce the anterior joint space because of the acetabular anteversion. However, most often, the lesions are in the anterior and superior regions, and most surgeons prefer to internally rotate the lower extremity to avoid this anterior joint space narrowing on a traction table. Internal rotation moves the sciatic nerve anteriorly and thus puts it at risk if the surgeon chooses a posterolateral portal approach. Invasive hip distraction avoids this by allowing for a controlled anterior-to-posterior traction vector in neutral rotation (Figure 12-3, A and B). A posterolateral portal approach is thus very safe without putting the sciatic nerve at risk.

Figure 12–3 A, Schematic view of a left hip with four Schanz screws in place showing the anterior-to-posterior traction forces that open the anterior joint space without the need for internal rotation. B, Anteroposterior schematic view of a right hip with the proximal acetabular and distal femoral Schanz screws.

Surgical technique

We have tried the lateral and supine approaches for this indication. We are largely in favor of the lateral decubitus position, and the setup is in a way that is similar to that of the classic lateral approach, with some differences. Three standard arthroscopy portals are used: the posterolateral portal, the anterolateral portal, and the anterior portal (Figure 12-4).

Figure 12–4 Proximal view of the setup of a right hip with invasive distraction and posterolateral (PL), anterolateral (AL), and anterior (A) portals.

We have abandoned the use of a traction table for hip arthroscopy as a result of a high associated neurologic complication rate. Although we followed the standard recommendations to avoid the neurologic complications of hip arthroscopy that were found in the literature (e.g., the use of a very large perineal post), of our first 20 cases, two slowly regressive pudendal nerve lesions with clinical impotence were encountered. These complications were likely the result of the fact that more than 90 minutes of traction were used to correct complex acetabular anomalies. We now have experience with more than 1000 cases of hip arthroscopy, and, sadly, our operative and traction times have not changed; this is because more and more complex cases are operated on arthroscopically and because labral suturing is necessary in about a third of cases. In the case of labral suturing, an average of four anchors is necessary, with some cases requiring eight anchors; this anchoring is of course time consuming, and it puts the nerves at risk. For this reason, since 2000, we have been using an invasive hip distraction device (see Figure 12-1, A and B), which is still in use at our institution. The device avoids the use of the perineal post, which is responsible for the pudendal nerve lesions. For more than 1000 cases, we have not documented a single nerve lesion as a result of traction with this type of hip distraction. Neurologic complication rates from procedures that involve the use of traction tables can be as high as 10% to 15%. These complications are certainly also related to experience with the technique and thus also to traction times. However, as mentioned previously in the case of complex surgery, the acetabular corrective surgery can be time consuming, particularly if labral reattachment or autologous cartilage transplantation is involved.

We prefer the lateral approach and invasive hip distraction for the following practical reasons:

• For the beginner, it is always possible if technical difficulties are encountered to convert to mini open or open surgery without redraping; this would not easily be the case if a standard traction table were being used. If necessary, conversion to a mini posterior approach is always possible with the patient in the lateral position rather than the supine position. We can compare this with the beach-chair position used for shoulder arthroscopy. An example of when this would occur would be in case of instrument breakage. Indeed, instruments tend to slide on the posterior horn of the acetabulum in the direction of the ligamentum transversum, and extraction can be difficult. With the patient in the lateral decubitus position, instruments fall into the pulvinar and are stopped by fatty tissue from sliding farther, and extraction is thus easier.

• Invasive hip distraction avoids the dreadful neurologic complications caused by lengthy distraction times in difficult or complex reconstructive hip arthroscopies. Thus, beginners feel no time pressure, and more complex hip reconstructions (e.g., labral detachment, described later in this chapter) and suturing are possible.

• Invasive hip distraction can be easily freed to dynamically test impingement-free motions of the hip during and after surgery (i.e., maximum flexion, 90 degrees of flexion, maximum internal rotation, and maximum abduction). These can be tested without difficulty (and in the same manner in which they are tested in open surgery) to ascertain that no impingement is present. Another advantage of this approach is that there is no compromise of surgical sterility unlike with a traction table where sterility may be compromised with a non-sterile traction boot.

• Finally, with the patient in the lateral decubitus position, bubbles that come from radiofrequency devices are easily evacuated through incisions; this is in contrast with having patients in the supine position, where such bubbles tend to accumulate anteriorly.

The lower extremity is draped so that it can be moved freely (Figure 12-5, A and B). The C-arm fluoroscope is brought under the table and draped, thus providing a good anterior-to-posterior view (see Figure 12-2, A through E, and 12-5, A and B). The invasive hip distractor is set up with the patient in slight hip flexion. One dedicated Schanz screw is placed 1 cm above the acetabular sourcil under image intensifier control, and another is placed at the level of the lesser trochanter. The proximal screws are in line with the anterior trochanteric margin (see Figure 12-3, A and B, and 12-6, B). The relative positions of the proximal and distal Schanz screws produce an anterior-to-posterior traction vector that optimizes the anterior joint space opening, even if no lower limb internal rotation is applied. The invasive hip distractor is installed on the inserted Schanz screws (see Figure 12-6, A through C). The device has a precision screw mechanism that can move the tubes precisely so that they fit onto the Schanz screws. After the distractor is installed, two other Schanz screws—one proximally in the acetabulum and one distally in the femur—are applied through the distractor’s guiding tubes (see Figure 12-6, C). This stabilizes the rotational forces and allows for a better anterior-to-posterior distraction vector. Bolts are then put on every Schanz screw to push the tubes around the screws down onto the bone. The whole hip distractor is thus an angularly stable construct that improves traction forces. After the invasive hip distractor is installed, distraction is applied on the hip by turning the axial distraction screw (see Figure 12-1, A and B). The lower extremity is then set in abduction of approximately 30 degrees to 45 degrees (see Figure 12-5, A and B). This maneuver and the previously mentioned slight flexion of about 10 degrees will relax the superior and anterior hip capsule, including the iliofemoral ligament, and this will permit better distraction (see Figure 12-5, B). With adequate distraction (ideally 12 mm), the hip joint is decompressed with a large spinal needle, and the suction seal is broken. However, about 5% of hips are considered not distractable or insufficiently distractable on traction tables. In these cases, invasive hip distraction can be useful by permitting for controlled capsular releases, which is described later in this chapter. With the use of a cannulated system, the arthroscope is first introduced into the anterolateral portal (see Figure 12-4). We prefer using the 70-degree scope, which provides a better view initially, especially in tighter joints. The posterolateral and anterior portals are then created under direct visual control, with the labrum and the femoral head being avoided. The hip is first viewed under air, and this is followed by fluid.