Femoroacetabular impingement (FAI) is an abnormal abutment between femoral head-neck junction and acetabular rim or labrum. FAI has been studied for the last decade as an etiologic factor of osteoarthritis (OA) of hip. FAI commonly encountered in orthopedic practice may also be cause of intractable hip pain. Lavigne et al.1) and Ganz et al.2) have advocated early surgical intervention for symptomatic FAI because of its possible relationship with OA of hip. They have introduced a safe approach called surgical hip dislocation (SHD) to hip joint without the risk of avascular necrosis of hip¹2). Others have used less invasive anterior mini-open (AMO) approach for surgical debridement of impingement as a modified Smith-Petersion approach for periacetabular osteotomy (PAO)³4). Whichever surgical method is utilized, the surgical goal is to eliminate impingement of femoral head-neck junction on acetabular rim by removing bony outgrowth of femoral head-neck area, acetabular rim, or both. We may well think older age is a relative contraindiation for hip preservation surgery, but it is just surrogate for degree of cartilage damage. Therefore, is should not be used as absolute marker for cartilage status. As long as we know, there was only one report about the SHD for FAI in patients over the age of 40 years5). Therefore, here we report the short term results of open surgical treatment for symptomatic FAI in nonatheletic patients over 30 years without advanced arthritic change of hip joint.

In this report, we described the degree of clinical pain relief and the change in clinical function score in nonathletic patients over 30 years with open treatment for intractable hip pain caused by FAI. We also assessed the change of radiographic parameters for FAI after surgical treatment and any progression of radiological Tönnis grade (Table 1) at last follow-up. In addition, we described the complications associated with open treatment for FAI.

In this study, we investigated short term results of open surgical treatment for symptomatic FAI and found favorable outcomes in clinical and radiological aspects. Nonsurgical treatment such as rehabilitation or observation may be used because there are many cases of nonsymptomatic FAI. But, It is usually proposed that early surgical intervention for treatment for FAI, besides providing relief of symptoms, may decelerate the progression of the degenerative process for young age group11). So, it is thought to be desirable to perform surgery for FAI patients fulfilling the inclusion criteria indicated in material and method.

Various surgical treatment approaches have been utilized to treat FAI^3,4,12,1314). SHD, advocated by Ganz et al.2), is a technique with full access to the femoral head and acetabulum. It has been used for treating FAI^12,1314). So, it was thought to be the gold standard for FAI approach. Peters et al.13) reported that at short-tem follow up, SHD treatment for FAI reduced pain and improved function with low complication in cases without substantial acetabular cartilage damage. Steppacher et al.14) reported that at 5-year follow-up, 91% of patients with FAI treated with SHD, osteoplasty, or labral reattachment showed no total hip arthroplasty, progression of OA, or an insufficient clinical result. It is imperative to preserve MFCA in SHD to prevent secondary avascular necrosis of femoral head. Distal portion of modified Smith-Peterson approach used in performing PAO has been utilized to treat FAI. This was called AMO. Cohen et al.3) and Parvizi et al.4) reported promising mid-term results of FAI with AMO approach. This may be thought to be a less invasive approach than SHD. But, it permit limited field of view only and can be complicated with bothersome meralgia paresthetica³4). A comprehensive comparison of these two approaches is impossible and beyond the scope of this study. But, briefly comparing these two surgical approaches concerning operative time and blood loss, we might well find that those of SHD were longer and more than those of AMO. The operative time of SHD became shortened from about 4 hours to 2 hours or so as operative skill improved. The amount of blood loss of SHD was slightly smaller than that of total hip arthroplasty, which was attributable to obviation of acetabular reaming and femoral neck cutting without resultant extensive exposure of cancellous bone which may cause copious bone bleeding.

Nowadays, arthroscopic technique is rapidly developing. Arthroscopic results for FAI are reported to be comparable to open treatment15). But all of the FAI deformites couldn't be corrected satisfactorily by arthroscopic technique alone. Its advantages include relative noninvasiveness and obviation of trochanteric osteotomy. It is primarily utilized for decompression of cam lesion. However, it might be very technically challenging to address labral refixation with competence. Not all the FAI deformities could be corrected satisfactorily by arthroscopic technique alone. We needed to be competent in open SHD or AMI treatment before switching to arthroscopic technique. Therefore, we have implemented open treatment first for FAI. From last year on, we have used arthroscopic method to address cam lesion. Hopefully we will be able to develop this technique skillfully so that we can address pincer lesion as well cam lesion in the future.

It is a focused concern whether to refix acetabular labrum or leave it alone in hip preservation surgery. Acetabular labrum is generally believed to create a seal to promote fluid-film lubrication of the hip joint and chondrocyte nutrition by limiting the rate of fluid egression from articular cartilage16). Its injury is thought to generate sufficient pain to require intervention17). Many authors have reported favorable clinical result of labral refixation or reconstructon rather than labrectomy¹⁸19). Espinosa et al.18) reported that patients treated with labral refixation recovered earlier with superior clinical and radiographic results compared to patients who had undergone resection of a torn labrum. Many authors have reported labral pathology as consistent findings concomitant with FAI. Peters et al.13) found 82 labral abnormalities in 92 hips, including detachment, tear, degenerative, calcification, and absent from previous surgery. We couldn't find any gross labral pathology except for one case of acetabular global overcoverage with partially calcified labrum.

Acetabular chondral damage was also reported to be frequent findings in FAI, especially of the cam type. Beck et al.20) found acetabular chondral damage in all 26 pure cam type FAIs with 10 chondral delaminations. Anderson et al.21) reported acetabular cartilage delamination in 44% of patients who underwent surgical dislocation of hip. After labral takedown, we also scrutinized for acetabular chondral damage by probing peripheral area. Although we could not find gross delamination, defect, or flap tear, we frequently found dark reddish discoloration along the margin of acetabular cartilage, which was assumed to be area of longstanding impingement. We might have overlooked microscopic damages that might be present. Such results might also be due to the less frequent impingement or less degree of cam deformity in our cases. They might not be severe enough to cause acetabular chondral delamination or labral injury. In the corresponding area in the femoral head-neck junction, we were able to find periosteal blushing and/or fibrocystic degeneration consistently in all thirteen cases. Peters et al.22) reported that this periosteal blushing indicating ecchymosis and osseous reaction is frequently observed in SHD for FAI and this area is delineated for femoral osteochondroplasty. This finding was consistent with that of this study. This reaction of the result of repetitive impingement of long duration is an inflammation biochemically, so may well be a cause of hip pain in absence of any labral or chondral damage. The degree of these changes might correlate with the severity of pain and indicate how wide femoral osteochondroplasty should be executed, which was also indicated by Peters et al22).

Concerning contributing factors to early failure of SHD of FAI, it has been reported that excessive acetabular trimming, OA, and increased age and weight were major culprits14). Older age may also be related to poor outcome after SHD for FAI treatment. Steppacher et al.14) reported that one of the strongest predictors for failure was age >40 years, which represented a relative contraindication. Increased or decreased BMI was also reported to be related to early failure¹⁴23). The cartilage overload caused by increased BMI might lead to early failure. On the other hand, decreased BMI might be related to early conversion to total hip replacement if combined with microinstability caused by rim resection23).

There may be complications related to open treatment. Concerning complications related to SHD treatment for FAI, Yun et al.24) reported a 20% incidence of trochanteric nonunon requiring refixation. Beaulé et al.25) reported 9 (24%) cases of trochanteric bursitis requiring screw removal and one trochanteric nonunion needing refixation. Our series didn't show any case of nonunion or malunion at the last follow-up except one (case #4) in which slight malreduction of osteotomized greater trochanter led to my decision to rereduce and refix the osteotomy site postoperatively. This trochanteric osteotomy-related complication might be related to technical problem. We drilled and tapped three holes toward lessor trochanter before flip osteotomy of the greater trochanter to reduce osteotomized fragment and insert screws easily. One major concern of SHD may be the development of avascular necrosis of femoral head. In a large series of SHD, there was no reported case of avascular necrosis2). As long as MFCA is preserved, SHD is a safe approach. The technique of preserving MFCA is well described with particular interest to osteotomy plane superficial to piriformis2). The main disadvantage of AMO approach is the possibility of injuring lateral femoral cutaneous nerve. Cohen et al.3) reported that mild meraglia paresthetica caused by stretching occurred in 9 of 44 (20%) cases after AMO surgery. They were resolved within 1 year postoperatively in all patients3). To prevent this from happening, it is recommended to incise fascia lata encasing tensor fascia lata and sartorius about 1 cm laterally away from the interval between these two muscles. We encountered this complication in one case (case #10) of three AMO cases, which was abated at the last follow-up. Two of SHD cases had residual pain, the cause of which was not verified clearly. The plausible causes are inadequate decompression, secondary instability, or intra-articular adhesions etc26).

There are several limitations of this study. First, this study was retrospectively designed. Second, very limited number of patients were included in the study. Third, there was no control group. Fourth, the follow-up period was short. However, the number of FAI requiring operation is never enough to perform prospective, randomized, and controlled study. Although we cannot inform whether correction of impingement by open method may prevent early onset OA of hip in non-athletics because of these limitations, it was ascertained that there were really bony impingements in presumed FAI patients that caused intractable hip pain in non-athletics. It was also determined that pain originated from impingement could be reproducibly and expectedly relieved in these patients at short term follow-up. In addition, we found that hip function could be improved significantly after surgical restoration of femoro-acetabular clearance at short term follow-up.

Symptomatic FAI was surely a cause of intractable hip pain. Open treatment of FAI was a reliable and effective treatment method with little or no complications in symptomatic FAIs patients over the age of 30 years without advanced arthritic change of hip joint at short term follow-up.