26

hip arthroscopy

frontiers and limitations

ANIL S. RANAWAT, MD

BRIAN J. REBOLLEDO, MD

JACQUELINE M. BRADY, MD

Editor’s Note: Noted hip surgeon Anil Ranawat seems the right person to state where hip arthroscopy is headed over the next 2 to 3 years. From the Ranawat first family of hip surgery, Anil was born to do this. It is not surprising he chose his dad for the opening quote. Rumor has it that all the Ranawat middle names translate to mean “hip.” In this chapter, Anil and his 2 younger colleagues make some bold statements about the direction of hip arthroscopy.

WHY ME?

After all, he was only 20 years old.

The strapping mid-fielder never envisioned that hip pain would be the ailment to slow him down so early in his career.

After last year’s playoff run, his team was supposed to be a serious contender. At first, the pain was manageable, but now in the crunch time of the season, the pain was a lot worse and medications were not doing the trick.

Finally, at the insistence of his mother, he called his team physician and came in right away for an evaluation. From all the off-season conditioning he felt strong, but certain maneuvers agonizingly aggravated the same darn groin pain. As the doctor pressed down on his flexed and internally rotated hip, he winced. “That’s it, doc! That’s the pain,” he exclaimed. The doctor held up the X-ray and waved his finger over an image of his hip. A “bump,” he called it, along the neck of his femur was the likely culprit. What was apparent on X-ray was better defined by an MRI. He also had a labral tear. “It is a good thing,” said the doctor. “We can fix this for you.”

COMPUTERIZED NAVIGATION AND ROBOTICS FOR CAM RESECTIONS (FIGURE 26-1)

A common reason for failure of hip arthroscopy is incomplete resection of a cam lesion^1,2 or sometimes resecting too much. A previous chapter talked about the importance of sphericity of the femoral head, and how loss of that causes injury to the acetabular labrum during the hip’s range of motion.³ Artful removal of the “bump” of a cam lesion, with restoration of sphericity, is the key to success for that type of impingement.

During femoral neck osteochondroplasty of a cam resection, the surgeon uses the combination of an arthroscopic shaver and burr to re-contour the femoral head and neck so that hip motion has minimal impingement on the chondrolabral junction. Direct intraoperative assessment of cam impingement is tricky, particularly while the lower extremity is captured in a traction device and the whole operative field is captured by just a 2-dimensional screen. Preoperative planning has also been limited by the absence of tools to understand how much of the cam bump to resect and how much not to. The 2-dimensional representation of a 3-dimensional problem doesn’t quite do it. For instance, the “alpha angle” gives us a point where the femoral head loses its sphericity. However, it does not indicate the proximal and distal extent of the lesion on the femoral neck, nor quantify in any way the overall size or volume of the culprit bony lesion. Clohisy et al shouted this frustration when they called the utility of that same “angle” into question. They found basically the same range of values in patients with and without symptoms of impingement.⁴ The relationships between the femoral heads and acetabula are affected in numerous ways, certainly by the shapes of the ball and the socket and, more importantly, by a combination of the 2 surfaces.

Three-dimensional CT scanning provides surgeons a means of visualizing clearly the location and extent of the cam lesion (Figure 26-2). Surface renderings help evaluate osseous impingements caused by either the proximal femur or pelvis side.⁵ The location and size of each cam lesion are generally defined according to the clock face of the roughly spherical femoral head. The overall volume of the bony prominence area is actually very calculable.

This technology introduces several promising opportunities. The learning curve of hip arthroscopy, and particularly cam lesion resection, is known to be very “gradual.” That means the surgeon must do many cases before he/she can perform consistently and confidently.6 Therefore, a navigation system makes great sense. It seems a great stride toward the standardization of cam resection, both for the individual surgeon as well as for reducing the variability between surgeons.

In addition, trainees striving to master the surgical techniques in hip arthroscopy can do it with the 3-dimensional navigation device both in the laboratory during practice and on the operating suite “playing field” and live patients. A recent review by Nawabi et al argues for it. In that paper, navigation and robotic-assisted hip arthroscopy seemed to allow for more accurate osseous resection than did free-handed technqiues.⁷ Cartiaux et al showed in a sawbones model that navigation and robot-assisted cutting devices were superior in accuracy than free-hand cuts.⁸ We still don’t know the costs of all this nor the overall cost-effectiveness. And we still certainly don’t know how much, if any, it will bring with respect to overall clinical success.

But we will know these things soon.

HIP ARTHROSCOPY FOR EVALUATING THE PAINFUL TOTAL HIP

Another frontier for hip arthroscopy is the periprosthetic setting. Knee arthroscopy has long been used in the treatment of painful knee arthroplasty, and for the same reasons that Dr. Byrd points out, indications for periprosthetic hip arthroscopy have evolved more slowly. The new arthroscopic techniques actually allow us to see areas near the total hip better. Think of what can be done with these tiny scopes. We can inspect for signs of infection, to obtain a biopsy, or to assess wear or bone resorption. Then we can do procedures such as resect scar or symptom-causing adhesions.^9,10

Early and proper diagnosis and treatment of infection associated with total hip arthroplasty can be life-saving. Removal of the prosthesis or any of the parts can be morbid. In the past, precise assessment has been difficult. One essentially had to guess based on clinical signs and symptoms. Now, suspected septic arthritis of both the native and prosthetic hip have become excellent indications for hip arthroscopy, culture, irrigation, and even synovectomy.^11,12 Some surgeons have particularly low thresholds to arthroscope the hip for suspected infection following total hip arthroplasty.^9,13 In some cases the decision to remove the prosthesis may be clear, based on a draining wound, elevated inflammatory markers, and positive aspirate cultures.^14–20 However, in most cases that decision is not so clear, and both the physician and patient don’t want to remove it without the firmest evidence possible. Most of the time, patients have borderline serum markers, some redness around the wound, no drainage, and negative cultures. Plus, the patients usually don’t feel or look too bad.

Hip arthroscopy is just plain simpler than the old open way of going into the hip. The surgeon has the ability to visualize the hip joint and obtain tissue cultures for analysis without subjecting patients to the risks of dislocation, secondary infection, and poor wound healing. The minimally invasive approach reduces the overall risk of medical complications.^21–23 Tissue histology and cultures are key in the ultimate decision and are now necessary components of the work-up for suspected periprosthetic infection. The tools used in hip arthroscopy permit so much more to be done with much less risk.24,25 The arthroscopic setting, of course, does not afford the surgeon to exchange any prosthetic components. That can be done as a second stage if necessary.

ARTHROSCOPY FOR SYMPTOMATIC HIP DYSPLASIA

Hip preservation remains the main goal in developmental dysplasia of the hip (DDH). The methods to achieve this are somewhat challenging and controversial. Hip arthroscopy has several promising and seemingly appropriate roles. It is proving promising for the treatment of selected patients with pain. During periacetabular osteotomy, hip arthroscopy can help visualize the acetabular cartilage to be rotated into weightbearing positions. That can be quite helpful to maximize the chance of reducing pain after the osteotomy.²⁶ Arthroscopy can also help with labral fixation and capsular closure.

There is uncertainty with regard to the potential benefit of the latter procedures. As our indications for hip arthroscopy expand, it becomes increasingly important to analyze our outcomes critically. Perhaps nowhere else is this more important than in these patients with DDH.

There are a huge number of patients with painful hips but who don’t quite fit the criteria for periacetabular osteotomy, such as those on the inner part of the spectrum of hip dysplasia (eg, lateral center-edge angle 20 to 25 degrees). The treatment remains controversial. Periacetabular osteotomy might seem too invasive, while hip arthroscopists worry about the potential for worsening symptoms, by exacerbating the dysplasia with their labral debridement or acetabular rim decompression. Despite the worry about causing hip instability, some hip arthroscopy techniques are showing promise for treating “microinstability” in selected settings of both traditional, global dysplasia and focal acetabular undercoverage.

One should not necessarily underplay the likelihood that the ligamentum teres contributes to stabilization of the native adult hip, especially during flexion, adduction, and external rotation. In addition to its known contribution to the blood supply of the pediatric hip, the ligament both contributes to the blood supply of the pediatric hip and has mechanoreceptors and nociceptors, which likely contribute to mechanical and proprioceptive factors involved in hip stability.²⁷ When there is both dysplasia and gross instability, the ligamentum teres is often torn. The ligament is traditionally sacrificed in open hip surgery. In contrast, arthroscopic reconstruction of the ligamentum teres may well aid with hip stabilization in any patient with deficient acetabular coverage.^28–30

ARTHRO-ENDOSCOPIC PROCEDURES AROUND THE HIP

Don’t forget that there is a large musculoskeletal world around the ball-and-socket hip joint that seems amenable to endoscopic procedures. The hip arthroscope can be utilized, and it seems we could design better scopes for that purpose. The hip arthroscope has already been used to assist in such things as proximal hamstring repair, psoas release, and nerve decompression. Such endoscopic procedures have the benefits of image magnification and limited exposure³¹ and avoid such structures as the gluteus maximus and the sciatic nerve. Indications for hip endoscopy within the peritrochanteric space have expanded (eg, for refractory trochanteric bursitis and abductor tendon repair). The early results seem promising.^32–34 The hip arthroscope has shown promise for sciatic nerve decompression and piriformis syndrome.^35,36 Other extra-articular hip disease has also been attacked that way,³⁷ such as deep gluteal syndrome, another kind of sciatic nerve entrapment, involving the gluteus maximus, ischial tunnel syndrome, and pudendal nerve entrapment. The results are not all in.

The iliopsoas muscle/tendon deserves special mention in this section. It can compress the chondrolabral complex as it crosses over the acetabulum and create unusual labral pathology, leading to degeneration, inflammation, and tears. Domb et al described results addressing iliopsoas impingement by arthroscopic tenotomy, which resulted in improved postoperative clinical outcomes.³⁸ The labral injury is distinct from dysplasia and femoroacetabular impingement (FAI), in that the position of labral insult is located at the 3 o’clock position, where the tendon traverses. This is in contrast to FAI and dysplasia, where the neck impinges usually at the 1 o’clock position.

Young patients with chondral lesions have also benefited from recent advances with hip arthroscopy. Success has been shown with microfracture,³⁹ mosaicplasty,^40,41 osteochondral allograft transplantation,⁴² and autologous chondrocyte implantation in the hip.⁴³ The early reports show promise, but these are mostly case series with limited long-term followup. Many of these techniques derive from articular cartilage-saving techniques of the knee. Some show great promise in stopping ongoing chondral degeneration.

Montgomery et al report a 365% increase in hip arthroscopic procedures in the United States since 2004.44 This is due to a combination of increased number of trainees and a proliferation of innovative technical advances.⁴⁵ The advances and improving outcomes have called for expanded indications. Now many patients severely afflicted with hip pain can live better lives and hopefully avoid hip replacements.

However, hip arthroscopy continues to evolve and certain limitations remain. Certain complex hip disorders and patient populations pose particular risk. The procedure is not for everybody. Now let’s highlight specific hip disorders that pose special challenges to us hip arthroscopists.

FEMOROACETABULAR IMPINGEMENT MORPHOLOGIC CHALLENGES

Osteochondral Defects

Hip arthroscopy effectively addresses various morphologies, including cam, pincer, and mixed-type FAI. By its nature, FAI may abnormally contact other areas of the hip not so easily addressed. The altered relationship between the head and acetabulum links to early osteoarthritic changes.⁴⁶ While not exclusive to FAI, one such problem is the osteochondral defect. This is thought to be a relative instability, resulting in shearing of the cartilage covering the femoral head. This poses a significant problem for the young patient not yet a candidate for arthroplasty.

Hip arthroscopy has provided a number of options to address the management of this difficult problem, but none of them are totally satisfactory. The limited blood supply and poor capacity for healing of the osteochondrum ensures a complex problem. Preventing further degenerative disease is difficult. Targeted strategies using hip arthroscopy include osteochondral allograft transplantation (OAT),^42,47,48 autologous chondrocyte implantation (ACI),^43,49 mosaicplasty,^41,50 and microfracture of the affected area^39,51,52 (Figure 26-3). Stafford et al reported 43 patients who underwent the use of fibrin adhesive for treatment of delaminated articular chondral damage to the femoral head.⁵³ They reported significant clinical and functional improvement in these patients up to 3 years after treatment. While relative success has been reported with these strategies, case reports and small case series still dominate the literature.

Related posts:

Putting It All Together—A Patient’s Perspective on the Core How the Core Universe Forms The Final Stage of Rehab—Getting All the Way Back The Other Muscles—Hip and Core Stability Biomechanics Presenting…the Core!

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