Cam- and pincer-type femoroacetabular impingement

Transcription

1 Case Report With Video Illustration Making a Case for Anterior Inferior Iliac Spine/Subspine Hip Impingement: Three Representative Case Reports and Proposed Concept Christopher M. Larson, M.D., Bryan T. Kelly, M.D., and Rebecca M. Stone, M.S., A.T.C. Abstract: Femoroacetabular impingement is typically described as occurring due to a conflict between the femoral head-neck junction and acetabular rim. A prior case report described an open decompression of the anterior inferior iliac spine (AIIS) due to impingement against the proximal femur. AIIS impingement may be developmental or the result of a prior AIIS avulsion or pelvic osteotomy. We describe 3 representative cases with minimum 1-year follow-up treated with an arthroscopic AIIS decompression. Cam- and pincer-type femoroacetabular impingement (FAI) has been well described in recent years. 1-8 Although much of the focus has been regarding the femoral head-neck junction and acetabular rim, extra-articular sources of impingement are being increasingly recognized. 9,10 The anterior inferior iliac spine (AIIS) represents the origin of the direct head of the rectus femoris tendon, and its bony morphology can be quite variable. The AIIS can result in impingement against the distal femoral neck with excessive distal and/or anterior extension and can be developmental in nature or due to prior AIIS avulsions or From the Minnesota Orthopedic Sports Medicine Institute at Twin Cities Orthopedics (C.M.L., R.M.S.), Edina, Minnesota; and New York-Presbyterian Hospital/Weill Cornell Medical College and Hospital for Special Surgery (B.T.K.), New York, New York, U.S.A. Received September 2, 2011; accepted October 6, Address correspondence to Christopher M. Larson, M.D., Minnesota Orthopedic Sports Medicine Institute at Twin Cities Orthopedics, 4010 W 65th St, Edina, MN 55435, U.S.A. chrislarson@tcomn.com 2011 by the Arthroscopy Association of North America /11552/$36.00 doi: /j.arthro Note: To access the video accompanying this report, visit the December issue of Arthroscopy at pelvic osteotomies. 9 To our knowledge, there has been only 1 prior case report describing AIIS impingement that was treated with an open decompression. 9 We present 3 representative cases of AIIS or subspine impingement treated with arthroscopic decompression with minimum 1-year follow-up. The typical clinical presentation, imaging, and intraoperative findings are also described. CASE 1 The first case is a 21-year-old collegiate soccer player who presented with increasing left-sided groin pain (Video 1, available at She described a grinding sensation with flexion and rotation of her hip and pain with athletic activity and prolonged hip flexion. Physical examination showed pain with hip flexion, internal rotation, and adduction and limited hip flexion to 105. Radiographs showed a mildly decreased femoral head-neck offset and a deep acetabulum with a positive crossover sign and ischial spine sign indicative of acetabular retroversion (Fig 1). Because of continued activity limitations, the patient underwent arthroscopic rim resection, labral refixation, and femoral resection osteoplasty (Fig 1). She continued to have limited flex Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 27, No 12 (December), 2011: pp

2 AIIS/SUBSPINE HIP IMPINGEMENT 1733 FIGURE 1. (A) An anteroposterior radiograph of the left hip in a 21-year-old collegiate soccer player shows a crossover sign (dotted line) consistent with acetabular retroversion. (B, C) Three-dimensional computed tomography scans show the area of acetabular overcoverage anteriorly (arrow). (D) The patient continued to have pain and motion limitations with straight hip flexion, and an anteroposterior radiograph obtained 1 year postoperatively identifies the rim resection and shows a persistently low AIIS (arrow). (E, F) Threedimensional computed tomography scans confirm anterior rim resection (black arrow) with an AIIS with prominent distal and anterior extension (white arrows). (G) The 3-dimensional computed tomography scan was imported into a software program (software prototype; A2 Surgical), and a simulated dynamic test for impingement was performed. (H) Impingement of the AIIS against the femoral neck was suspected, and the areas of impingement were marked with blue highlighting by the program. (I) The patient underwent repeat arthroscopy with an arthroscopic AIIS decompression. (L, labrum; AIIS, decompressed anterior inferior iliac spine.) (J) The post AIIS decompression anteroposterior radiograph shows AIIS decompression (arrow). The patient returned to soccer without limitations, and hip flexion was restored to normal.

3 1734 C. M. LARSON ET AL. FIGURE 2. (A) An anteroposterior pelvis radiograph in a 17-year-old high school hockey player shows a prominent left AIIS (arrow) that developed after a pelvic osteotomy at age 3 years. The patient continued to have hip pain and hip flexion limitations, and an arthroscopic AIIS decompression was performed. (B) An anteroposterior pelvis radiograph after arthroscopy shows decompression of the AIIS (arrow). The patient returned to hockey without limitations, and hip flexion was restored to normal. ion and pain 1 year postoperatively, and imaging studies showed evidence of rim resection and what we believed to be a prominently low and anterior AIIS. Her 3-dimensional computed tomography scan was imported into a software program (software prototype; A2 Surgical, St. Pierre d Allevard, France) that allowed for simulated dynamic testing and showed that the primary area of residual impingement appeared to be related to the AIIS (Fig 1, Video 1). An intra-articular anesthetic injection provided minimal pain relief. On the basis of the previously mentioned findings, we offered the patient a referral for an open surgical procedure versus an arthroscopic AIIS decompression. She subsequently underwent an arthroscopic decompression of the AIIS and had excellent pain relief, hip flexion improved to 125, and she was able to resume collegiate soccer with occasional mild discomfort but no limitations (Fig 1, Video 1). At 1 year after her revision arthroscopy, her modified Harris Hip Score (HHS) and visual analog scale (VAS) score were improved, with an HHS of 74 preoperatively versus 85 postoperatively and VAS score of 5.7 preoperatively versus 1.65 postoperatively. CASE 2 The second case is a 17-year-old high school hockey player who had undergone a pelvic osteotomy at age 3 years. She presented with groin pain with athletic activity and prolonged sitting, as well as a long history of limited hip flexion. Physical examination showed pain with hip flexion to 100. An intraarticular injection provided partial relief, and a magnetic resonance imaging study was unremarkable. Radiographs showed a lateral center-edge angle of 25 and what appeared to be a prominent AIIS (Fig 2). Because of continued disability, the patient underwent a hip arthroscopy and arthroscopic AIIS decompression (Fig 2). She subsequently returned to hockey with no pain, and hip flexion improved to 130. At 1.5 years after arthroscopy, her HHS and VAS score were improved, with an HHS of 74 preoperatively versus 100 postoperatively and VAS score of 4.85 preoperatively versus 0.0 postoperatively. CASE 3 The third case is a 31-year-old male recreational soccer player who had a history of a severe hip flexor injury 15 years previously (Video 1). He presented with increasing activity-related groin pain and a grinding sensation with flexion and lateral movements, as well as pain with prolonged sitting. Physical examination showed pain with straight hip flexion to 110 and pain with flexion, internal rotation, and adduction. Imaging studies showed a low AIIS due to prior AIIS avulsion and cam-type FAI (Fig 3). An intra-articular anesthetic injection provided 50% relief of his usual symptoms. Because of continued limitations, he underwent an arthroscopic labral repair, minimal anterior rim resection, femoral resection osteoplasty, and AIIS decompression (Fig 3, Video 1). After surgery, he was able to resume soccer without limitations, and his hip flexion was improved, at 125. At 1.5 years after arthroscopy, his HHS and VAS score were improved, with an HHS of 79 preoperatively versus 96 postoperatively and VAS score of 8.0 preoperatively versus 1.75 postoperatively.

4 AIIS/SUBSPINE HIP IMPINGEMENT 1735 FIGURE 3. (A, B) Anteroposterior and lateral pelvis radiographs in a 31-year-old recreational soccer player who had sustained a right hip flexor strain 15 years previously show a low AIIS (dotted lines) due to an AIIS avulsion and cam-type FAI (arrow). (C) A 3-dimensional computed tomography scan confirms cam-type FAI (dotted arrow) and an AIIS avulsion injury (solid arrow). Because of continued pain and limited hip flexion, the patient underwent an arthroscopic labral repair, femoral resection, and arthroscopic AIIS decompression. (D, E) Postoperative anteroposterior and lateral radiographs confirm AIIS decompression (dotted arrows) and femoral resection osteoplasty (solid arrow). Hip flexion was restored to normal. DISCUSSION FAI results from abnormal contact between the proximal femur and acetabular rim or pelvis. 1-8 An increasing number of structures have been implicated, and the pattern of impingement is variable. 1-3,9,10 There have been reports describing peritrochanteric and extracapsular hip endoscopy as well as an association between intra- and extra-articular hip pathology in some patients The AIIS represents the origin of the direct head of the rectus femoris. It has a variable morphology, but its role in extra-articular impingement is not well reported at this time. There is 1 prior case report, to our knowledge, describing a 30-year-old man with a prominent AIIS that was decompressed with an open approach and resulted in excellent pain relief and restoration of full hip flexion. 9 We have noted an increasing number of patients with a constellation of findings that we believe to represent extra-articular impingement of the AIIS against the femoral neck (Table 1). These patients typically present with groin pain with flexionbased activity, and they often describe a grinding sensation anteriorly with flexion and lateral movements (Table 1). Impingement cysts located further distal on the femoral neck than typically observed with acetabular rim impingement and increased sclerosis of the anterior acetabular rim on radiographs may also be consistent with AIIS impingement (Fig 4). This sclerotic appearance of the anterior rim appears to be related to overlap of the anterior rim with distal extension of the AIIS. When developmental AIIS or subspine impingement is suspected, it is often

5 1736 C. M. LARSON ET AL. seen in the setting of acetabular retroversion. Inferior or distal extension of the AIIS on anteroposterior radiographs can also be mistaken for acetabular retroversion if not carefully scrutinized. In addition to anterior rim overcoverage, the AIIS is often rotated further anteriorly and distally with acetabular retroversion. We have found 3-dimensional computed tomography scans to be invaluable when evaluating these patients, because they best depict true acetabular coverage and the AIIS and its associated morphology. When patients have the previously described presentation and the AIIS extends to or below the acetabular rim and/or has excessive anterior extension, we consider a decompression as part of an FAI corrective procedure. Specific intraoperative findings can help to confirm the diagnosis (Table 1). The AIIS can be decompressed at the level of the anterior rim and is easily identified by stripping the capsule up the AIIS with a combination of a shaver and a bur (Video 1). We have occasionally made a small longitudinal split in the rectus tendon to perform a more aggressive decompression when necessary. However, there may be some inherent risks of performing this procedure arthroscopically that will require further investigation. TABLE 1. Diagnostic Pearls Consistent With AIIS Impingement History and physical examination Anterior/groin pain with straight hip flexion Anterior pain with prolonged hip flexion Limited hip flexion range of motion on physical examination Tenderness to palpation over AIIS that re-creates typical pain Partial pain relief and persistent hip flexion limitations after intra-articular anesthetic hip injection Imaging studies Plain radiographs Evidence for prior AIIS avulsion Calcific deposits within rectus femoris origin Extension of AIIS below acetabular sourcil on anteroposterior pelvis radiograph Excessive anterior and distal extension of AIIS on falseprofile radiograph Acetabular retroversion with increased anterior rim sclerosis Impingement cysts located at distal femoral neck Three-dimensional computed tomography Deformity of AIIS from prior AIIS avulsion Excessive anterior extension of AIIS Extension of AIIS to or below anterior acetabular rim Intraoperative findings Focal synovitis anteriorly at level of AIIS Focal peripheral labral ecchymosis anteriorly at level of AIIS Focal bony buildup of anterior acetabular rim representing inferior extension of AIIS Calcific deposits within proximal rectus femoris FIGURE 4. An anteroposterior radiograph of the left hip in a 21-year-old butterfly goalie with hip pain, acetabular retroversion, a superior rim fracture, and cam-type FAI. Closer inspection shows a distal femoral neck impingement cyst (dotted arrow) and sclerotic appearance of the anterior acetabular rim (solid arrow). Both of these radiographic findings may be consistent with an element of AIIS impingement (Table 1). If an overly aggressive resection is performed, the rectus femoris could be detached from its origin, leading to a potential hip flexion deficit. Hip flexion weakness, however, has not been noted by us after an AIIS decompression, likely because of a broad periosteal attachment of the rectus femoris to the AIIS and anterior pelvis. In addition, although a more aggressive capsulotomy might increase the potential risk for intra-abdominal fluid extravasation, this has not been encountered by us after AIIS decompression. It is unclear whether this represents strictly bony impingement, strictly impingement of the rectus femoris, or a combination of both. Further studies and a specific classification system are needed to better define the appropriate indications and surgical approach when managing this entity. CONCLUSIONS FAI is an evolving concept with varying patterns of intra- and extra-articular impingement being discovered. The AIIS may be a source of pain and impingement in a subset of patients and can be developmental or due to prior pelvic osteotomy or AIIS avulsion. An arthroscopic AIIS decompression is feasible in some

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