Hip Arthroscopy: Its Role in the Treatment of FAI

Douglas Naudie, M.D., FRCSC
Assistant Professor, Department of Surgery (Orthopaedics)
University of Western Ontario
London, Ontario

Femoroacetabular impingement, or FAI, is a hip disorder characterized by impaired joint clearance between the femoral head/neck and acetabulum. Two types have been described: cam and pincer impingement1. Cam impingement is caused by an abnormality - insufficient concavity or "offset" of the anterolateral femoral head-neck junction. This incongruity between the femoral head/neck and acetabulum can result in compressive forces and injury to the labrum or adjacent chondral surface. Cam impingement typically presents in males, with the onset of symptoms between 30-39 years. Any deformity of the femoral head or neck causing femoral retroversion or decreased head/neck offset can result in cam impingement; these include femoral neck retroversion, Legg-Calvé-Perthes disease, slipped capital femoral epiphysis, or malunited femoral neck fractures. Pincer impingement results from excess coverage of the femoral head by the acetabulum causing contact between the labrum and femoral neck during hip motion. Compressive forces are transferred to the lip of the acetabulum, with resulting injury to the labrum and underlying cartilage. Pincer impingement most often presents in females between the ages of 40-49. Predisposing factors for this problem include a retroverted acetabulum or coxa profunda.

 

The diagnosis of FAI is made mainly on history and physical examination. However, there are important imaging findings that can help to support the diagnosis2. Hip X-rays are the most important diagnostic tool, with anteroposterior pelvic radiographs confirming retroversion or coxa profunda, and cross-table lateral radiographs confirming femoral head asphericity and decreased femoral head-neck offset. MRI and especially MR arthrography (with gadolinium) are useful in the assessment of the labrum and articular cartilage. When conservative treatment options have failed, surgery may be indicated. A variety of surgical techniques have been utilized to treat pre-arthritic and early arthritic hip impingement disease3. These techniques include surgical dislocation of the hip, periacetabular osteotomy, combined hip arthroscopy and a limited open exposure, and all-arthroscopic techniques. The goals of these surgical interventions are to relieve pain, enhance activity and function, and preserve the natural hip joint over time.

 

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Figure 1a
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Figure 1b
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Figure 1c

 

Figure 1a: Central compartment hip arthroscopy of a female patient demonstrating anterior acetabular chondral delamination.
Figure 1b: Central compartment hip arthroscopy of the same patient after labral debridement exposing the pincer impingement lesion.
Figure 1c: Central compartment hip arthroscopy of the same patient prior to arthroscopic acetabular rim trimming.

Although these surgical techniques stem from sound rationale regarding hip impingement disease, the published clinical results associated with these procedures are limited. The purpose of this communication is to briefly review the role of hip arthroscopy in the treatment of FAI. Two questions need to be specifically addressed. First, can FAI disorders not requiring periacetabular osteotomy be managed arthroscopically? Second, can we accomplish recontouring of the femoral head/neck junction or acetabulum comparable to open techniques? In reviewing the literature on this subject it is important to determine the level of clinical evidence regarding arthroscopic FAI surgery, to define the impact of impingement surgery on pain relief and hip function, and to evaluate treatment failures and complications associated with these procedures.

Three papers have reported the clinical outcomes of hip impingement surgery treated arthroscopically at one year follow-up4-6. Byrd and Jones (2009) prospectively assessed 200 patients (207 hips) who underwent arthroscopic correction of FAI using a modified Harris Hip Score4. One hundred and fifty-eight patients (163 hips) underwent correction of cam impingement alone while 42 patients (44 hips) underwent concomitant correction of pincer impingement. At a minimum follow-up of 12 months, the average increase in Harris hip score was 20 points. There was a 1.5% complication rate, with 0.5% converted to total hip arthroplasty. Larson and Giveans (2008) reported on 96 consecutive patients (100 hips) with radiographically documented FAI treated with hip arthroscopy, labral debridement or repair/refixation, femoral osteochondroplasty, acetabular rim trimming, or some combination thereof5. At a mean follow-up of 9.9 months, the authors reported a significant improvement for all outcomes measured: Harris Hip Score, Short Form 12, visual analog score for pain, and positive impingement test. The alpha angle was also significantly improved after resection osteochondroplasty. These authors do report, however, six cases of heterotopic bone formation, three hips requiring total hip arthroplasty, and one partial sciatic nerve neuropraxia (one hip). Bardakos et al (2008) compared the results of hip arthroscopy for cam-type femoroacetabular impingement in two groups of patients at one year6. The study group comprised 24 patients (24 hips) with cam-type impingement who underwent arthroscopic debridement with excision of their impingement lesion; the control group comprised 47 patients (47 hips) who had arthroscopic debridement without excision of the impingement lesion. These authors observed a higher median postoperative modified Harris Hip Score and a significantly higher proportion of patients with excellent/good results in the study group compared with the control group. Although these studies report favourable clinical outcomes, particularly with the ability to perform a femoral osteochondroplasty, they are all single surgeon cohorts with a very short-term (one-year) follow-up.

 

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Figure 2a
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Figure 2b

 

Figure 2a: Peripheral compartment hip arthroscopy of a young male patient with visualization of a cam type impingement lesion at the anterolateral femoral head/neck junction.
Figure 2b: Peripheral compartment arthroscopy of the same patient after arthroscopic femoral osteochondroplasty

Four studies report clinical outcomes of FAI treated arthroscopically with a minimum follow-up of two years (Table 1)7-10. These studies are all retrospective case series, and thus provide Level IV evidence. They document short-term improvement with decreased pain and improved function in the majority of patients. The largest of these studies reports a 9% conversion rate to total hip arthroplasty. These studies all underscore the benefits of arthroscopic impingement surgery, and suggest that long-term symptom relief and joint preservation is a possibility. These studies also propose that certain factors are associated with a fair or poor clinical result and/or surgical failure. These poor prognostic factors, although variably reported, include more advanced preoperative osteoarthritis, advanced articular cartilage disease, older age and more severe preoperative pain. These studies fail to report complications, but all suggest that arthroscopic impingement procedures are relatively safe, with minimal risk for major perioperative complications.

In answering our proposed questions, therefore, it appears that FAI disorders not requiring periacetabular osteotomy can indeed be managed arthroscopically. Pincer-type impingement can be managed through central compartment arthroscopy (Figure 1). Selective debridement or takedown of the damaged labrum exposes impinging bone, which can be excised with the use of an arthroscopic burr. This can be facilitated by switching the arthroscope and instruments back and forth between anterior and anterolateral portals. Cam-type impingement can be managed by the creation of a capsular window in the peripheral compartment (Figure 2). Femoral osteochondroplasty, or resection of the impingement lesion, can also be accomplished with an arthroscopic burr. Resection begins at the junction of healthy articular surface and then tapers distally. It is especially important to avoid notching the bone distally on the cortical neck of the femur, which could create a stress riser and possibly a femoral neck fracture.

Furthermore, the current review of the literature suggests that we can accomplish recontouring of the femoral head/neck junction or acetabulum comparable to open techniques. The preliminary short-term data suggests that both open and arthroscopic hip impingement surgery is associated with early relief of symptoms and improved function. Alteration in the natural progression to osteoarthritis and sustained pain relief as a result of arthroscopic management of FAI remain to be seen. Future research initiatives in this discipline must focus on: 1) developing refined and standardized endpoints to study this patient population more precisely, and 2) studying large patient populations to better answer clinically relevant questions.

Table 1: Studies evaluating arthroscopic management of FAI with minimum 2-year follow-up

Study

Hips/patients

Diagnosis (%)

Clinical outcome scores

Good or Excellent outcome (%)

Conversion to THA (%)

Complications

Philippon et al.
(JBJS Br 2009)

112/112

Cam (20.5%)
Pincer (2.5%)
Combined (77%)

MHHS, HOOS ADL, HOOS Sport, NAHS

NA

10 (9%)

NR

Brunner et al.
(AJSM 2009)

53/53

Cam (58%)
Combined (42%)

SFS, NAHS, VAS

NA

NA

NR

Ilizaliturri et al.
(J Arthroplasty 2008)

19/19

Cam (100%)

WOMAC

16 (84%)

1 (5%)

NR

Ilizaliturri et al.
(JBJS-Br 2007)

14/13

Cam (93%)
Combined (7%)

WOMAC

NA

NA

NR

MHHS=Modified Harris Hip Score
HOOS=Hip Outcome Score
NAHS=Non-arthritic hip score
NA=Data Not Available
NR=Data Not Reported
VAS=Visual Analog Pain Scale

References

  1. Ganz R., Parvizi J., Beck M., Leunig M., Notzli H., Siebenrock K. Femoroacetabular impingement: A cause for osteoarthritis of the hip. Clin Orthop Rel Res. 2003;417:112-120.
  2. Tannast M., Siebenrock K., Anderson S. Femoroacetabular Impingement: Radiographic Diagnosis-What the Radiologist should know. American Journal Radiology 2007;188:1540-1552.
  3. Lavigne M., Parvizi J., Beck M., Siebenrock K.A., Ganz R., Leunig M. Anterior femoroacetabular impingement: part I. Techniques of joint preserving surgery. Clin Orthop Relat Res. 2004 Jan;(418):61-6.
  4. Byrd J.W., Jones K.S. Arthroscopic femoroplasty in the management of cam-type femoroacetabular impingement. Clin Orthop Relat Res. 2009;467(3):739-746.
  5. Larson C.M., Giveans M.R. Arthroscopic debridement versus refixation of the acetabular labrum associated with femoroacetabular impingement. Arthroscopy. 2009;25(4):369-376.
  6. Bardakos N.V., Vasconcelos J.C., Villar R.N. Early outcome of hip arthroscopy for femoroacetabular impingement: the role of femoral osteoplasty in symptomatic improvement. J Bone Joint Surg Br. 2008;90(12):1570-1575.
  7. Philippon M.J., Briggs K.K., Yen Y.M., Kuppersmith D.A. Outcomes following hip arthroscopy for femoroacetabular impingement with associated chondrolabral dysfunction: minimum two-year follow-up. J Bone Joint Surg Br. 2009;91(1):16-23.
  8. Brunner A., Horisberger M., Herzog RF. Sports and Recreation Activity of Patients With Femoroacetabular Impingement Before and After Arthroscopic Osteoplasty. Am J Sports Med. 2009.
  9. Ilizaliturri V.M., Jr., Orozco-Rodriguez L., Acosta-Rodriguez E., Camacho-Galindo J. Arthroscopic treatment of cam-type femoroacetabular impingement: preliminary report at 2 years minimum follow-up. J Arthroplasty. 2008;23(2):226-234.
  10. Ilizaliturri V.M., Jr., Nossa-Barrera J.M., Acosta-Rodriguez E., Camacho-Galindo J. Arthroscopic treatment of femoroacetabular impingement secondary to paediatric hip disorders. J Bone Joint Surg Br. 2007;89(8):1025-1030.

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